Merge tag 'trace-3.10' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:
"Along with the usual minor fixes and clean ups there are a few major
changes with this pull request.

1) Multiple buffers for the ftrace facility

This feature has been requested by many people over the last few
years. I even heard that Google was about to implement it themselves.
I finally had time and cleaned up the code such that you can now
create multiple instances of the ftrace buffer and have different
events go to different buffers. This way, a low frequency event will
not be lost in the noise of a high frequency event.

Note, currently only events can go to different buffers, the tracers
(ie function, function_graph and the latency tracers) still can only
be written to the main buffer.

2) The function tracer triggers have now been extended.

The function tracer had two triggers. One to enable tracing when a
function is hit, and one to disable tracing. Now you can record a
stack trace on a single (or many) function(s), take a snapshot of the
buffer (copy it to the snapshot buffer), and you can enable or disable
an event to be traced when a function is hit.

3) A perf clock has been added.

A "perf" clock can be chosen to be used when tracing. This will cause
ftrace to use the same clock as perf uses, and hopefully this will
make it easier to interleave the perf and ftrace data for analysis."

* tag 'trace-3.10' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (82 commits)
tracepoints: Prevent null probe from being added
tracing: Compare to 1 instead of zero for is_signed_type()
tracing: Remove obsolete macro guard _TRACE_PROFILE_INIT
ftrace: Get rid of ftrace_profile_bits
tracing: Check return value of tracing_init_dentry()
tracing: Get rid of unneeded key calculation in ftrace_hash_move()
tracing: Reset ftrace_graph_filter_enabled if count is zero
tracing: Fix off-by-one on allocating stat->pages
kernel: tracing: Use strlcpy instead of strncpy
tracing: Update debugfs README file
tracing: Fix ftrace_dump()
tracing: Rename trace_event_mutex to trace_event_sem
tracing: Fix comment about prefix in arch_syscall_match_sym_name()
tracing: Convert trace_destroy_fields() to static
tracing: Move find_event_field() into trace_events.c
tracing: Use TRACE_MAX_PRINT instead of constant
tracing: Use pr_warn_once instead of open coded implementation
ring-buffer: Add ring buffer startup selftest
tracing: Bring Documentation/trace/ftrace.txt up to date
tracing: Add "perf" trace_clock
...

Conflicts:
kernel/trace/ftrace.c
kernel/trace/trace.c

Documentation/kernel-parameters.txt

···
 			on: enable for both 32- and 64-bit processes
 			off: disable for both 32- and 64-bit processes
 
+	alloc_snapshot	[FTRACE]
+			Allocate the ftrace snapshot buffer on boot up when the
+			main buffer is allocated. This is handy if debugging
+			and you need to use tracing_snapshot() on boot up, and
+			do not want to use tracing_snapshot_alloc() as it needs
+			to be done where GFP_KERNEL allocations are allowed.
+
 	amd_iommu=	[HW,X86-64]
 			Pass parameters to the AMD IOMMU driver in the system.
 			Possible values are:

Documentation/trace/ftrace.txt

···
 Reviewers:   Elias Oltmanns, Randy Dunlap, Andrew Morton,
 	     John Kacur, and David Teigland.
 Written for: 2.6.28-rc2
+Updated for: 3.10
 
 Introduction
 ------------
···
 It can be used for debugging or analyzing latencies and
 performance issues that take place outside of user-space.
 
-Although ftrace is the function tracer, it also includes an
-infrastructure that allows for other types of tracing. Some of
-the tracers that are currently in ftrace include a tracer to
-trace context switches, the time it takes for a high priority
-task to run after it was woken up, the time interrupts are
-disabled, and more (ftrace allows for tracer plugins, which
-means that the list of tracers can always grow).
+Although ftrace is typically considered the function tracer, it
+is really a frame work of several assorted tracing utilities.
+There's latency tracing to examine what occurs between interrupts
+disabled and enabled, as well as for preemption and from a time
+a task is woken to the task is actually scheduled in.
+
+One of the most common uses of ftrace is the event tracing.
+Through out the kernel is hundreds of static event points that
+can be enabled via the debugfs file system to see what is
+going on in certain parts of the kernel.
 
 
 Implementation Details
···
 
 That's it! (assuming that you have ftrace configured into your kernel)
 
-After mounting the debugfs, you can see a directory called
+After mounting debugfs, you can see a directory called
 "tracing".  This directory contains the control and output files
 of ftrace. Here is a list of some of the key files:
 
···
 
 	This sets or displays whether writing to the trace
 	ring buffer is enabled. Echo 0 into this file to disable
-	the tracer or 1 to enable it.
+	the tracer or 1 to enable it. Note, this only disables
+	writing to the ring buffer, the tracing overhead may
+	still be occurring.
 
   trace:
 
···
 
 	This file lets the user control the amount of data
 	that is displayed in one of the above output
-	files.
+	files. Options also exist to modify how a tracer
+	or events work (stack traces, timestamps, etc).
+
+  options:
+
+	This is a directory that has a file for every available
+	trace option (also in trace_options). Options may also be set
+	or cleared by writing a "1" or "0" respectively into the
+	corresponding file with the option name.
 
   tracing_max_latency:
 
···
 	latency is greater than the value in this
 	file. (in microseconds)
 
+  tracing_thresh:
+
+	Some latency tracers will record a trace whenever the
+	latency is greater than the number in this file.
+	Only active when the file contains a number greater than 0.
+	(in microseconds)
+
   buffer_size_kb:
 
 	This sets or displays the number of kilobytes each CPU
-	buffer can hold. The tracer buffers are the same size
+	buffer holds. By default, the trace buffers are the same size
 	for each CPU. The displayed number is the size of the
 	CPU buffer and not total size of all buffers. The
 	trace buffers are allocated in pages (blocks of memory
···
 	than requested, the rest of the page will be used,
 	making the actual allocation bigger than requested.
 	( Note, the size may not be a multiple of the page size
-	  due to buffer management overhead. )
+	  due to buffer management meta-data. )
 
-	This can only be updated when the current_tracer
-	is set to "nop".
+  buffer_total_size_kb:
+
+	This displays the total combined size of all the trace buffers.
+
+  free_buffer:
+
+	If a process is performing the tracing, and the ring buffer
+	should be shrunk "freed" when the process is finished, even
+	if it were to be killed by a signal, this file can be used
+	for that purpose. On close of this file, the ring buffer will
+	be resized to its minimum size. Having a process that is tracing
+	also open this file, when the process exits its file descriptor
+	for this file will be closed, and in doing so, the ring buffer
+	will be "freed".
+
+	It may also stop tracing if disable_on_free option is set.
 
   tracing_cpumask:
 
 	This is a mask that lets the user only trace
-	on specified CPUS. The format is a hex string
-	representing the CPUS.
+	on specified CPUs. The format is a hex string
+	representing the CPUs.
 
   set_ftrace_filter:
 
···
 	"set_ftrace_notrace". (See the section "dynamic ftrace"
 	below for more details.)
 
+  enabled_functions:
+
+	This file is more for debugging ftrace, but can also be useful
+	in seeing if any function has a callback attached to it.
+	Not only does the trace infrastructure use ftrace function
+	trace utility, but other subsystems might too. This file
+	displays all functions that have a callback attached to them
+	as well as the number of callbacks that have been attached.
+	Note, a callback may also call multiple functions which will
+	not be listed in this count.
+
+	If the callback registered to be traced by a function with
+	the "save regs" attribute (thus even more overhead), a 'R'
+	will be displayed on the same line as the function that
+	is returning registers.
+
+  function_profile_enabled:
+
+	When set it will enable all functions with either the function
+	tracer, or if enabled, the function graph tracer. It will
+	keep a histogram of the number of functions that were called
+	and if run with the function graph tracer, it will also keep
+	track of the time spent in those functions. The histogram
+	content can be displayed in the files:
+
+	trace_stats/function<cpu> ( function0, function1, etc).
+
+  trace_stats:
+
+	A directory that holds different tracing stats.
+
+  kprobe_events:
+ 
+	Enable dynamic trace points. See kprobetrace.txt.
+
+  kprobe_profile:
+
+	Dynamic trace points stats. See kprobetrace.txt.
+
+  max_graph_depth:
+
+	Used with the function graph tracer. This is the max depth
+	it will trace into a function. Setting this to a value of
+	one will show only the first kernel function that is called
+	from user space.
+
+  printk_formats:
+
+	This is for tools that read the raw format files. If an event in
+	the ring buffer references a string (currently only trace_printk()
+	does this), only a pointer to the string is recorded into the buffer
+	and not the string itself. This prevents tools from knowing what
+	that string was. This file displays the string and address for
+	the string allowing tools to map the pointers to what the
+	strings were.
+
+  saved_cmdlines:
+
+	Only the pid of the task is recorded in a trace event unless
+	the event specifically saves the task comm as well. Ftrace
+	makes a cache of pid mappings to comms to try to display
+	comms for events. If a pid for a comm is not listed, then
+	"<...>" is displayed in the output.
+
+  snapshot:
+
+	This displays the "snapshot" buffer and also lets the user
+	take a snapshot of the current running trace.
+	See the "Snapshot" section below for more details.
+
+  stack_max_size:
+
+	When the stack tracer is activated, this will display the
+	maximum stack size it has encountered.
+	See the "Stack Trace" section below.
+
+  stack_trace:
+
+	This displays the stack back trace of the largest stack
+	that was encountered when the stack tracer is activated.
+	See the "Stack Trace" section below.
+
+  stack_trace_filter:
+
+	This is similar to "set_ftrace_filter" but it limits what
+	functions the stack tracer will check.
+
+  trace_clock:
+
+	Whenever an event is recorded into the ring buffer, a
+	"timestamp" is added. This stamp comes from a specified
+	clock. By default, ftrace uses the "local" clock. This
+	clock is very fast and strictly per cpu, but on some
+	systems it may not be monotonic with respect to other
+	CPUs. In other words, the local clocks may not be in sync
+	with local clocks on other CPUs.
+
+	Usual clocks for tracing:
+
+	  # cat trace_clock
+	  [local] global counter x86-tsc
+
+	  local: Default clock, but may not be in sync across CPUs
+
+	  global: This clock is in sync with all CPUs but may
+	  	  be a bit slower than the local clock.
+
+	  counter: This is not a clock at all, but literally an atomic
+	  	   counter. It counts up one by one, but is in sync
+		   with all CPUs. This is useful when you need to
+		   know exactly the order events occurred with respect to
+		   each other on different CPUs.
+
+	  uptime: This uses the jiffies counter and the time stamp
+	  	  is relative to the time since boot up.
+
+	  perf: This makes ftrace use the same clock that perf uses.
+	  	Eventually perf will be able to read ftrace buffers
+		and this will help out in interleaving the data.
+
+	  x86-tsc: Architectures may define their own clocks. For
+	  	   example, x86 uses its own TSC cycle clock here.
+
+	To set a clock, simply echo the clock name into this file.
+
+	  echo global > trace_clock
+
+  trace_marker:
+
+	This is a very useful file for synchronizing user space
+	with events happening in the kernel. Writing strings into
+	this file will be written into the ftrace buffer.
+
+	It is useful in applications to open this file at the start
+	of the application and just reference the file descriptor
+	for the file.
+
+	void trace_write(const char *fmt, ...)
+	{
+		va_list ap;
+		char buf[256];
+		int n;
+
+		if (trace_fd < 0)
+			return;
+
+		va_start(ap, fmt);
+		n = vsnprintf(buf, 256, fmt, ap);
+		va_end(ap);
+
+		write(trace_fd, buf, n);
+	}
+
+	start:
+
+		trace_fd = open("trace_marker", WR_ONLY);
+
+  uprobe_events:
+ 
+	Add dynamic tracepoints in programs.
+	See uprobetracer.txt
+
+  uprobe_profile:
+
+	Uprobe statistics. See uprobetrace.txt
+
+  instances:
+
+	This is a way to make multiple trace buffers where different
+	events can be recorded in different buffers.
+	See "Instances" section below.
+
+  events:
+
+	This is the trace event directory. It holds event tracepoints
+	(also known as static tracepoints) that have been compiled
+	into the kernel. It shows what event tracepoints exist
+	and how they are grouped by system. There are "enable"
+	files at various levels that can enable the tracepoints
+	when a "1" is written to them.
+
+	See events.txt for more information.
+
+  per_cpu:
+
+	This is a directory that contains the trace per_cpu information.
+
+  per_cpu/cpu0/buffer_size_kb:
+
+	The ftrace buffer is defined per_cpu. That is, there's a separate
+	buffer for each CPU to allow writes to be done atomically,
+	and free from cache bouncing. These buffers may have different
+	size buffers. This file is similar to the buffer_size_kb
+	file, but it only displays or sets the buffer size for the
+	specific CPU. (here cpu0).
+
+  per_cpu/cpu0/trace:
+
+	This is similar to the "trace" file, but it will only display
+	the data specific for the CPU. If written to, it only clears
+	the specific CPU buffer.
+
+  per_cpu/cpu0/trace_pipe
+
+	This is similar to the "trace_pipe" file, and is a consuming
+	read, but it will only display (and consume) the data specific
+	for the CPU.
+
+  per_cpu/cpu0/trace_pipe_raw
+
+	For tools that can parse the ftrace ring buffer binary format,
+	the trace_pipe_raw file can be used to extract the data
+	from the ring buffer directly. With the use of the splice()
+	system call, the buffer data can be quickly transferred to
+	a file or to the network where a server is collecting the
+	data.
+
+	Like trace_pipe, this is a consuming reader, where multiple
+	reads will always produce different data.
+
+  per_cpu/cpu0/snapshot:
+
+	This is similar to the main "snapshot" file, but will only
+	snapshot the current CPU (if supported). It only displays
+	the content of the snapshot for a given CPU, and if
+	written to, only clears this CPU buffer.
+
+  per_cpu/cpu0/snapshot_raw:
+
+	Similar to the trace_pipe_raw, but will read the binary format
+	from the snapshot buffer for the given CPU.
+
+  per_cpu/cpu0/stats:
+
+	This displays certain stats about the ring buffer:
+
+	 entries: The number of events that are still in the buffer.
+
+	 overrun: The number of lost events due to overwriting when
+	 	  the buffer was full.
+
+	 commit overrun: Should always be zero.
+	 	This gets set if so many events happened within a nested
+		event (ring buffer is re-entrant), that it fills the
+		buffer and starts dropping events.
+
+	 bytes: Bytes actually read (not overwritten).
+
+	 oldest event ts: The oldest timestamp in the buffer
+
+	 now ts: The current timestamp
+
+	 dropped events: Events lost due to overwrite option being off.
+
+	 read events: The number of events read.
 
 The Tracers
 -----------
···
         RT tasks (as the current "wakeup" does). This is useful
         for those interested in wake up timings of RT tasks.
 
-  "hw-branch-tracer"
-
-	Uses the BTS CPU feature on x86 CPUs to traces all
-	branches executed.
-
   "nop"
 
 	This is the "trace nothing" tracer. To remove all
···
                              --------
 # tracer: function
 #
-#           TASK-PID   CPU#    TIMESTAMP  FUNCTION
-#              | |      |          |         |
-            bash-4251  [01] 10152.583854: path_put <-path_walk
-            bash-4251  [01] 10152.583855: dput <-path_put
-            bash-4251  [01] 10152.583855: _atomic_dec_and_lock <-dput
+# entries-in-buffer/entries-written: 140080/250280   #P:4
+#
+#                              _-----=> irqs-off
+#                             / _----=> need-resched
+#                            | / _---=> hardirq/softirq
+#                            || / _--=> preempt-depth
+#                            ||| /     delay
+#           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
+#              | |       |   ||||       |         |
+            bash-1977  [000] .... 17284.993652: sys_close <-system_call_fastpath
+            bash-1977  [000] .... 17284.993653: __close_fd <-sys_close
+            bash-1977  [000] .... 17284.993653: _raw_spin_lock <-__close_fd
+            sshd-1974  [003] .... 17284.993653: __srcu_read_unlock <-fsnotify
+            bash-1977  [000] .... 17284.993654: add_preempt_count <-_raw_spin_lock
+            bash-1977  [000] ...1 17284.993655: _raw_spin_unlock <-__close_fd
+            bash-1977  [000] ...1 17284.993656: sub_preempt_count <-_raw_spin_unlock
+            bash-1977  [000] .... 17284.993657: filp_close <-__close_fd
+            bash-1977  [000] .... 17284.993657: dnotify_flush <-filp_close
+            sshd-1974  [003] .... 17284.993658: sys_select <-system_call_fastpath
                              --------
 
 A header is printed with the tracer name that is represented by
-the trace. In this case the tracer is "function". Then a header
-showing the format. Task name "bash", the task PID "4251", the
-CPU that it was running on "01", the timestamp in <secs>.<usecs>
-format, the function name that was traced "path_put" and the
-parent function that called this function "path_walk". The
-timestamp is the time at which the function was entered.
+the trace. In this case the tracer is "function". Then it shows the
+number of events in the buffer as well as the total number of entries
+that were written. The difference is the number of entries that were
+lost due to the buffer filling up (250280 - 140080 = 110200 events
+lost).
+
+The header explains the content of the events. Task name "bash", the task
+PID "1977", the CPU that it was running on "000", the latency format
+(explained below), the timestamp in <secs>.<usecs> format, the
+function name that was traced "sys_close" and the parent function that
+called this function "system_call_fastpath". The timestamp is the time
+at which the function was entered.
 
 Latency trace format
 --------------------
 
-When the latency-format option is enabled, the trace file gives
-somewhat more information to see why a latency happened.
-Here is a typical trace.
+When the latency-format option is enabled or when one of the latency
+tracers is set, the trace file gives somewhat more information to see
+why a latency happened. Here is a typical trace.
 
 # tracer: irqsoff
 #
-irqsoff latency trace v1.1.5 on 2.6.26-rc8
---------------------------------------------------------------------
- latency: 97 us, #3/3, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
-    -----------------
-    | task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0)
-    -----------------
- => started at: apic_timer_interrupt
- => ended at:   do_softirq
-
-#                _------=> CPU#
-#               / _-----=> irqs-off
-#              | / _----=> need-resched
-#              || / _---=> hardirq/softirq
-#              ||| / _--=> preempt-depth
-#              |||| /
-#              |||||     delay
-#  cmd     pid ||||| time  |   caller
-#     \   /    |||||   \   |   /
-  <idle>-0     0d..1    0us+: trace_hardirqs_off_thunk (apic_timer_interrupt)
-  <idle>-0     0d.s.   97us : __do_softirq (do_softirq)
-  <idle>-0     0d.s1   98us : trace_hardirqs_on (do_softirq)
+# irqsoff latency trace v1.1.5 on 3.8.0-test+
+# --------------------------------------------------------------------
+# latency: 259 us, #4/4, CPU#2 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:4)
+#    -----------------
+#    | task: ps-6143 (uid:0 nice:0 policy:0 rt_prio:0)
+#    -----------------
+#  => started at: __lock_task_sighand
+#  => ended at:   _raw_spin_unlock_irqrestore
+#
+#
+#                  _------=> CPU#            
+#                 / _-----=> irqs-off        
+#                | / _----=> need-resched    
+#                || / _---=> hardirq/softirq 
+#                ||| / _--=> preempt-depth   
+#                |||| /     delay             
+#  cmd     pid   ||||| time  |   caller      
+#     \   /      |||||  \    |   /           
+      ps-6143    2d...    0us!: trace_hardirqs_off <-__lock_task_sighand
+      ps-6143    2d..1  259us+: trace_hardirqs_on <-_raw_spin_unlock_irqrestore
+      ps-6143    2d..1  263us+: time_hardirqs_on <-_raw_spin_unlock_irqrestore
+      ps-6143    2d..1  306us : <stack trace>
+ => trace_hardirqs_on_caller
+ => trace_hardirqs_on
+ => _raw_spin_unlock_irqrestore
+ => do_task_stat
+ => proc_tgid_stat
+ => proc_single_show
+ => seq_read
+ => vfs_read
+ => sys_read
+ => system_call_fastpath
 
 
 This shows that the current tracer is "irqsoff" tracing the time
-for which interrupts were disabled. It gives the trace version
-and the version of the kernel upon which this was executed on
-(2.6.26-rc8). Then it displays the max latency in microsecs (97
-us). The number of trace entries displayed and the total number
-recorded (both are three: #3/3). The type of preemption that was
-used (PREEMPT). VP, KP, SP, and HP are always zero and are
-reserved for later use. #P is the number of online CPUS (#P:2).
+for which interrupts were disabled. It gives the trace version (which
+never changes) and the version of the kernel upon which this was executed on
+(3.10). Then it displays the max latency in microseconds (259 us). The number
+of trace entries displayed and the total number (both are four: #4/4).
+VP, KP, SP, and HP are always zero and are reserved for later use.
+#P is the number of online CPUs (#P:4).
 
 The task is the process that was running when the latency
-occurred. (swapper pid: 0).
+occurred. (ps pid: 6143).
 
 The start and stop (the functions in which the interrupts were
 disabled and enabled respectively) that caused the latencies:
 
-  apic_timer_interrupt is where the interrupts were disabled.
-  do_softirq is where they were enabled again.
+ __lock_task_sighand is where the interrupts were disabled.
+ _raw_spin_unlock_irqrestore is where they were enabled again.
 
 The next lines after the header are the trace itself. The header
 explains which is which.
···
 
   The rest is the same as the 'trace' file.
 
+  Note, the latency tracers will usually end with a back trace
+  to easily find where the latency occurred.
 
 trace_options
 -------------
 
-The trace_options file is used to control what gets printed in
-the trace output. To see what is available, simply cat the file:
+The trace_options file (or the options directory) is used to control
+what gets printed in the trace output, or manipulate the tracers.
+To see what is available, simply cat the file:
 
   cat trace_options
-  print-parent nosym-offset nosym-addr noverbose noraw nohex nobin \
-  noblock nostacktrace nosched-tree nouserstacktrace nosym-userobj
+print-parent
+nosym-offset
+nosym-addr
+noverbose
+noraw
+nohex
+nobin
+noblock
+nostacktrace
+trace_printk
+noftrace_preempt
+nobranch
+annotate
+nouserstacktrace
+nosym-userobj
+noprintk-msg-only
+context-info
+latency-format
+sleep-time
+graph-time
+record-cmd
+overwrite
+nodisable_on_free
+irq-info
+markers
+function-trace
 
 To disable one of the options, echo in the option prepended with
 "no".
···
 
   bin - This will print out the formats in raw binary.
 
-  block - TBD (needs update)
+  block - When set, reading trace_pipe will not block when polled.
 
   stacktrace - This is one of the options that changes the trace
 	       itself. When a trace is recorded, so is the stack
 	       of functions. This allows for back traces of
 	       trace sites.
+
+  trace_printk - Can disable trace_printk() from writing into the buffer.
+
+  branch - Enable branch tracing with the tracer.
+
+  annotate - It is sometimes confusing when the CPU buffers are full
+  	     and one CPU buffer had a lot of events recently, thus
+	     a shorter time frame, were another CPU may have only had
+	     a few events, which lets it have older events. When
+	     the trace is reported, it shows the oldest events first,
+	     and it may look like only one CPU ran (the one with the
+	     oldest events). When the annotate option is set, it will
+	     display when a new CPU buffer started:
+
+          <idle>-0     [001] dNs4 21169.031481: wake_up_idle_cpu <-add_timer_on
+          <idle>-0     [001] dNs4 21169.031482: _raw_spin_unlock_irqrestore <-add_timer_on
+          <idle>-0     [001] .Ns4 21169.031484: sub_preempt_count <-_raw_spin_unlock_irqrestore
+##### CPU 2 buffer started ####
+          <idle>-0     [002] .N.1 21169.031484: rcu_idle_exit <-cpu_idle
+          <idle>-0     [001] .Ns3 21169.031484: _raw_spin_unlock <-clocksource_watchdog
+          <idle>-0     [001] .Ns3 21169.031485: sub_preempt_count <-_raw_spin_unlock
 
   userstacktrace - This option changes the trace. It records a
 		   stacktrace of the current userspace thread.
···
 		a.out-1623  [000] 40874.465068: /root/a.out[+0x480] <-/root/a.out[+0
 x494] <- /root/a.out[+0x4a8] <- /lib/libc-2.7.so[+0x1e1a6]
 
-  sched-tree - trace all tasks that are on the runqueue, at
-	       every scheduling event. Will add overhead if
-	       there's a lot of tasks running at once.
+
+  printk-msg-only - When set, trace_printk()s will only show the format
+  		    and not their parameters (if trace_bprintk() or
+		    trace_bputs() was used to save the trace_printk()).
+
+  context-info - Show only the event data. Hides the comm, PID,
+  	         timestamp, CPU, and other useful data.
 
   latency-format - This option changes the trace. When
                    it is enabled, the trace displays
···
                    latencies, as described in "Latency
                    trace format".
 
+  sleep-time - When running function graph tracer, to include
+  	       the time a task schedules out in its function.
+	       When enabled, it will account time the task has been
+	       scheduled out as part of the function call.
+
+  graph-time - When running function graph tracer, to include the
+  	       time to call nested functions. When this is not set,
+	       the time reported for the function will only include
+	       the time the function itself executed for, not the time
+	       for functions that it called.
+
+  record-cmd - When any event or tracer is enabled, a hook is enabled
+  	       in the sched_switch trace point to fill comm cache
+	       with mapped pids and comms. But this may cause some
+	       overhead, and if you only care about pids, and not the
+	       name of the task, disabling this option can lower the
+	       impact of tracing.
+
   overwrite - This controls what happens when the trace buffer is
               full. If "1" (default), the oldest events are
               discarded and overwritten. If "0", then the newest
               events are discarded.
+	        (see per_cpu/cpu0/stats for overrun and dropped)
 
-ftrace_enabled
---------------
+  disable_on_free - When the free_buffer is closed, tracing will
+  		    stop (tracing_on set to 0).
 
-The following tracers (listed below) give different output
-depending on whether or not the sysctl ftrace_enabled is set. To
-set ftrace_enabled, one can either use the sysctl function or
-set it via the proc file system interface.
+  irq-info - Shows the interrupt, preempt count, need resched data.
+  	     When disabled, the trace looks like:
 
-  sysctl kernel.ftrace_enabled=1
+# tracer: function
+#
+# entries-in-buffer/entries-written: 144405/9452052   #P:4
+#
+#           TASK-PID   CPU#      TIMESTAMP  FUNCTION
+#              | |       |          |         |
+          <idle>-0     [002]  23636.756054: ttwu_do_activate.constprop.89 <-try_to_wake_up
+          <idle>-0     [002]  23636.756054: activate_task <-ttwu_do_activate.constprop.89
+          <idle>-0     [002]  23636.756055: enqueue_task <-activate_task
 
- or
 
-  echo 1 > /proc/sys/kernel/ftrace_enabled
+  markers - When set, the trace_marker is writable (only by root).
+  	    When disabled, the trace_marker will error with EINVAL
+	    on write.
 
-To disable ftrace_enabled simply replace the '1' with '0' in the
-above commands.
 
-When ftrace_enabled is set the tracers will also record the
-functions that are within the trace. The descriptions of the
-tracers will also show an example with ftrace enabled.
+  function-trace - The latency tracers will enable function tracing
+  	    if this option is enabled (default it is). When
+	    it is disabled, the latency tracers do not trace
+	    functions. This keeps the overhead of the tracer down
+	    when performing latency tests.
+
+ Note: Some tracers have their own options. They only appear
+       when the tracer is active.
+
 
 
 irqsoff
···
 To reset the maximum, echo 0 into tracing_max_latency. Here is
 an example:
 
+ # echo 0 > options/function-trace
  # echo irqsoff > current_tracer
- # echo latency-format > trace_options
- # echo 0 > tracing_max_latency
  # echo 1 > tracing_on
+ # echo 0 > tracing_max_latency
  # ls -ltr
  [...]
  # echo 0 > tracing_on
  # cat trace
 # tracer: irqsoff
 #
-irqsoff latency trace v1.1.5 on 2.6.26
---------------------------------------------------------------------
- latency: 12 us, #3/3, CPU#1 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
-    -----------------
-    | task: bash-3730 (uid:0 nice:0 policy:0 rt_prio:0)
-    -----------------
- => started at: sys_setpgid
- => ended at:   sys_setpgid
+# irqsoff latency trace v1.1.5 on 3.8.0-test+
+# --------------------------------------------------------------------
+# latency: 16 us, #4/4, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:4)
+#    -----------------
+#    | task: swapper/0-0 (uid:0 nice:0 policy:0 rt_prio:0)
+#    -----------------
+#  => started at: run_timer_softirq
+#  => ended at:   run_timer_softirq
+#
+#
+#                  _------=> CPU#            
+#                 / _-----=> irqs-off        
+#                | / _----=> need-resched    
+#                || / _---=> hardirq/softirq 
+#                ||| / _--=> preempt-depth   
+#                |||| /     delay             
+#  cmd     pid   ||||| time  |   caller      
+#     \   /      |||||  \    |   /           
+  <idle>-0       0d.s2    0us+: _raw_spin_lock_irq <-run_timer_softirq
+  <idle>-0       0dNs3   17us : _raw_spin_unlock_irq <-run_timer_softirq
+  <idle>-0       0dNs3   17us+: trace_hardirqs_on <-run_timer_softirq
+  <idle>-0       0dNs3   25us : <stack trace>
+ => _raw_spin_unlock_irq
+ => run_timer_softirq
+ => __do_softirq
+ => call_softirq
+ => do_softirq
+ => irq_exit
+ => smp_apic_timer_interrupt
+ => apic_timer_interrupt
+ => rcu_idle_exit
+ => cpu_idle
+ => rest_init
+ => start_kernel
+ => x86_64_start_reservations
+ => x86_64_start_kernel
 
-#                _------=> CPU#
-#               / _-----=> irqs-off
-#              | / _----=> need-resched
-#              || / _---=> hardirq/softirq
-#              ||| / _--=> preempt-depth
-#              |||| /
-#              |||||     delay
-#  cmd     pid ||||| time  |   caller
-#     \   /    |||||   \   |   /
-    bash-3730  1d...    0us : _write_lock_irq (sys_setpgid)
-    bash-3730  1d..1    1us+: _write_unlock_irq (sys_setpgid)
-    bash-3730  1d..2   14us : trace_hardirqs_on (sys_setpgid)
-
-
-Here we see that that we had a latency of 12 microsecs (which is
-very good). The _write_lock_irq in sys_setpgid disabled
-interrupts. The difference between the 12 and the displayed
-timestamp 14us occurred because the clock was incremented
+Here we see that that we had a latency of 16 microseconds (which is
+very good). The _raw_spin_lock_irq in run_timer_softirq disabled
+interrupts. The difference between the 16 and the displayed
+timestamp 25us occurred because the clock was incremented
 between the time of recording the max latency and the time of
 recording the function that had that latency.
 
-Note the above example had ftrace_enabled not set. If we set the
-ftrace_enabled, we get a much larger output:
+Note the above example had function-trace not set. If we set
+function-trace, we get a much larger output:
+
+ with echo 1 > options/function-trace
 
 # tracer: irqsoff
 #
-irqsoff latency trace v1.1.5 on 2.6.26-rc8
---------------------------------------------------------------------
- latency: 50 us, #101/101, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
-    -----------------
-    | task: ls-4339 (uid:0 nice:0 policy:0 rt_prio:0)
-    -----------------
- => started at: __alloc_pages_internal
- => ended at:   __alloc_pages_internal
-
-#                _------=> CPU#
-#               / _-----=> irqs-off
-#              | / _----=> need-resched
-#              || / _---=> hardirq/softirq
-#              ||| / _--=> preempt-depth
-#              |||| /
-#              |||||     delay
-#  cmd     pid ||||| time  |   caller
-#     \   /    |||||   \   |   /
-      ls-4339  0...1    0us+: get_page_from_freelist (__alloc_pages_internal)
-      ls-4339  0d..1    3us : rmqueue_bulk (get_page_from_freelist)
-      ls-4339  0d..1    3us : _spin_lock (rmqueue_bulk)
-      ls-4339  0d..1    4us : add_preempt_count (_spin_lock)
-      ls-4339  0d..2    4us : __rmqueue (rmqueue_bulk)
-      ls-4339  0d..2    5us : __rmqueue_smallest (__rmqueue)
-      ls-4339  0d..2    5us : __mod_zone_page_state (__rmqueue_smallest)
-      ls-4339  0d..2    6us : __rmqueue (rmqueue_bulk)
-      ls-4339  0d..2    6us : __rmqueue_smallest (__rmqueue)
-      ls-4339  0d..2    7us : __mod_zone_page_state (__rmqueue_smallest)
-      ls-4339  0d..2    7us : __rmqueue (rmqueue_bulk)
-      ls-4339  0d..2    8us : __rmqueue_smallest (__rmqueue)
+# irqsoff latency trace v1.1.5 on 3.8.0-test+
+# --------------------------------------------------------------------
+# latency: 71 us, #168/168, CPU#3 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:4)
+#    -----------------
+#    | task: bash-2042 (uid:0 nice:0 policy:0 rt_prio:0)
+#    -----------------
+#  => started at: ata_scsi_queuecmd
+#  => ended at:   ata_scsi_queuecmd
+#
+#
+#                  _------=> CPU#            
+#                 / _-----=> irqs-off        
+#                | / _----=> need-resched    
+#                || / _---=> hardirq/softirq 
+#                ||| / _--=> preempt-depth   
+#                |||| /     delay             
+#  cmd     pid   ||||| time  |   caller      
+#     \   /      |||||  \    |   /           
+    bash-2042    3d...    0us : _raw_spin_lock_irqsave <-ata_scsi_queuecmd
+    bash-2042    3d...    0us : add_preempt_count <-_raw_spin_lock_irqsave
+    bash-2042    3d..1    1us : ata_scsi_find_dev <-ata_scsi_queuecmd
+    bash-2042    3d..1    1us : __ata_scsi_find_dev <-ata_scsi_find_dev
+    bash-2042    3d..1    2us : ata_find_dev.part.14 <-__ata_scsi_find_dev
+    bash-2042    3d..1    2us : ata_qc_new_init <-__ata_scsi_queuecmd
+    bash-2042    3d..1    3us : ata_sg_init <-__ata_scsi_queuecmd
+    bash-2042    3d..1    4us : ata_scsi_rw_xlat <-__ata_scsi_queuecmd
+    bash-2042    3d..1    4us : ata_build_rw_tf <-ata_scsi_rw_xlat
 [...]
-      ls-4339  0d..2   46us : __rmqueue_smallest (__rmqueue)
-      ls-4339  0d..2   47us : __mod_zone_page_state (__rmqueue_smallest)
-      ls-4339  0d..2   47us : __rmqueue (rmqueue_bulk)
-      ls-4339  0d..2   48us : __rmqueue_smallest (__rmqueue)
-      ls-4339  0d..2   48us : __mod_zone_page_state (__rmqueue_smallest)
-      ls-4339  0d..2   49us : _spin_unlock (rmqueue_bulk)
-      ls-4339  0d..2   49us : sub_preempt_count (_spin_unlock)
-      ls-4339  0d..1   50us : get_page_from_freelist (__alloc_pages_internal)
-      ls-4339  0d..2   51us : trace_hardirqs_on (__alloc_pages_internal)
+    bash-2042    3d..1   67us : delay_tsc <-__delay
+    bash-2042    3d..1   67us : add_preempt_count <-delay_tsc
+    bash-2042    3d..2   67us : sub_preempt_count <-delay_tsc
+    bash-2042    3d..1   67us : add_preempt_count <-delay_tsc
+    bash-2042    3d..2   68us : sub_preempt_count <-delay_tsc
+    bash-2042    3d..1   68us+: ata_bmdma_start <-ata_bmdma_qc_issue
+    bash-2042    3d..1   71us : _raw_spin_unlock_irqrestore <-ata_scsi_queuecmd
+    bash-2042    3d..1   71us : _raw_spin_unlock_irqrestore <-ata_scsi_queuecmd
+    bash-2042    3d..1   72us+: trace_hardirqs_on <-ata_scsi_queuecmd
+    bash-2042    3d..1  120us : <stack trace>
+ => _raw_spin_unlock_irqrestore
+ => ata_scsi_queuecmd
+ => scsi_dispatch_cmd
+ => scsi_request_fn
+ => __blk_run_queue_uncond
+ => __blk_run_queue
+ => blk_queue_bio
+ => generic_make_request
+ => submit_bio
+ => submit_bh
+ => __ext3_get_inode_loc
+ => ext3_iget
+ => ext3_lookup
+ => lookup_real
+ => __lookup_hash
+ => walk_component
+ => lookup_last
+ => path_lookupat
+ => filename_lookup
+ => user_path_at_empty
+ => user_path_at
+ => vfs_fstatat
+ => vfs_stat
+ => sys_newstat
+ => system_call_fastpath
 
 
-
-Here we traced a 50 microsecond latency. But we also see all the
+Here we traced a 71 microsecond latency. But we also see all the
 functions that were called during that time. Note that by
 enabling function tracing, we incur an added overhead. This
 overhead may extend the latency times. But nevertheless, this
···
 which preemption was disabled. The control of preemptoff tracer
 is much like the irqsoff tracer.
 
+ # echo 0 > options/function-trace
  # echo preemptoff > current_tracer
- # echo latency-format > trace_options
- # echo 0 > tracing_max_latency
  # echo 1 > tracing_on
+ # echo 0 > tracing_max_latency
  # ls -ltr
  [...]
  # echo 0 > tracing_on
  # cat trace
 # tracer: preemptoff
 #
-preemptoff latency trace v1.1.5 on 2.6.26-rc8
---------------------------------------------------------------------
- latency: 29 us, #3/3, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
-    -----------------
-    | task: sshd-4261 (uid:0 nice:0 policy:0 rt_prio:0)
-    -----------------
- => started at: do_IRQ
- => ended at:   __do_softirq
-
-#                _------=> CPU#
-#               / _-----=> irqs-off
-#              | / _----=> need-resched
-#              || / _---=> hardirq/softirq
-#              ||| / _--=> preempt-depth
-#              |||| /
-#              |||||     delay
-#  cmd     pid ||||| time  |   caller
-#     \   /    |||||   \   |   /
-    sshd-4261  0d.h.    0us+: irq_enter (do_IRQ)
-    sshd-4261  0d.s.   29us : _local_bh_enable (__do_softirq)
-    sshd-4261  0d.s1   30us : trace_preempt_on (__do_softirq)
+# preemptoff latency trace v1.1.5 on 3.8.0-test+
+# --------------------------------------------------------------------
+# latency: 46 us, #4/4, CPU#1 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:4)
+#    -----------------
+#    | task: sshd-1991 (uid:0 nice:0 policy:0 rt_prio:0)
+#    -----------------
+#  => started at: do_IRQ
+#  => ended at:   do_IRQ
+#
+#
+#                  _------=> CPU#            
+#                 / _-----=> irqs-off        
+#                | / _----=> need-resched    
+#                || / _---=> hardirq/softirq 
+#                ||| / _--=> preempt-depth   
+#                |||| /     delay             
+#  cmd     pid   ||||| time  |   caller      
+#     \   /      |||||  \    |   /           
+    sshd-1991    1d.h.    0us+: irq_enter <-do_IRQ
+    sshd-1991    1d..1   46us : irq_exit <-do_IRQ
+    sshd-1991    1d..1   47us+: trace_preempt_on <-do_IRQ
+    sshd-1991    1d..1   52us : <stack trace>
+ => sub_preempt_count
+ => irq_exit
+ => do_IRQ
+ => ret_from_intr
 
 
 This has some more changes. Preemption was disabled when an
-interrupt came in (notice the 'h'), and was enabled while doing
-a softirq. (notice the 's'). But we also see that interrupts
-have been disabled when entering the preempt off section and
-leaving it (the 'd'). We do not know if interrupts were enabled
-in the mean time.
+interrupt came in (notice the 'h'), and was enabled on exit.
+But we also see that interrupts have been disabled when entering
+the preempt off section and leaving it (the 'd'). We do not know if
+interrupts were enabled in the mean time or shortly after this
+was over.
 
 # tracer: preemptoff
 #
-preemptoff latency trace v1.1.5 on 2.6.26-rc8
---------------------------------------------------------------------
- latency: 63 us, #87/87, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
-    -----------------
-    | task: sshd-4261 (uid:0 nice:0 policy:0 rt_prio:0)
-    -----------------
- => started at: remove_wait_queue
- => ended at:   __do_softirq
-
-#                _------=> CPU#
-#               / _-----=> irqs-off
-#              | / _----=> need-resched
-#              || / _---=> hardirq/softirq
-#              ||| / _--=> preempt-depth
-#              |||| /
-#              |||||     delay
-#  cmd     pid ||||| time  |   caller
-#     \   /    |||||   \   |   /
-    sshd-4261  0d..1    0us : _spin_lock_irqsave (remove_wait_queue)
-    sshd-4261  0d..1    1us : _spin_unlock_irqrestore (remove_wait_queue)
-    sshd-4261  0d..1    2us : do_IRQ (common_interrupt)
-    sshd-4261  0d..1    2us : irq_enter (do_IRQ)
-    sshd-4261  0d..1    2us : idle_cpu (irq_enter)
-    sshd-4261  0d..1    3us : add_preempt_count (irq_enter)
-    sshd-4261  0d.h1    3us : idle_cpu (irq_enter)
-    sshd-4261  0d.h.    4us : handle_fasteoi_irq (do_IRQ)
+# preemptoff latency trace v1.1.5 on 3.8.0-test+
+# --------------------------------------------------------------------
+# latency: 83 us, #241/241, CPU#1 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:4)
+#    -----------------
+#    | task: bash-1994 (uid:0 nice:0 policy:0 rt_prio:0)
+#    -----------------
+#  => started at: wake_up_new_task
+#  => ended at:   task_rq_unlock
+#
+#
+#                  _------=> CPU#            
+#                 / _-----=> irqs-off        
+#                | / _----=> need-resched    
+#                || / _---=> hardirq/softirq 
+#                ||| / _--=> preempt-depth   
+#                |||| /     delay             
+#  cmd     pid   ||||| time  |   caller      
+#     \   /      |||||  \    |   /           
+    bash-1994    1d..1    0us : _raw_spin_lock_irqsave <-wake_up_new_task
+    bash-1994    1d..1    0us : select_task_rq_fair <-select_task_rq
+    bash-1994    1d..1    1us : __rcu_read_lock <-select_task_rq_fair
+    bash-1994    1d..1    1us : source_load <-select_task_rq_fair
+    bash-1994    1d..1    1us : source_load <-select_task_rq_fair
 [...]
-    sshd-4261  0d.h.   12us : add_preempt_count (_spin_lock)
-    sshd-4261  0d.h1   12us : ack_ioapic_quirk_irq (handle_fasteoi_irq)
-    sshd-4261  0d.h1   13us : move_native_irq (ack_ioapic_quirk_irq)
-    sshd-4261  0d.h1   13us : _spin_unlock (handle_fasteoi_irq)
-    sshd-4261  0d.h1   14us : sub_preempt_count (_spin_unlock)
-    sshd-4261  0d.h1   14us : irq_exit (do_IRQ)
-    sshd-4261  0d.h1   15us : sub_preempt_count (irq_exit)
-    sshd-4261  0d..2   15us : do_softirq (irq_exit)
-    sshd-4261  0d...   15us : __do_softirq (do_softirq)
-    sshd-4261  0d...   16us : __local_bh_disable (__do_softirq)
-    sshd-4261  0d...   16us+: add_preempt_count (__local_bh_disable)
-    sshd-4261  0d.s4   20us : add_preempt_count (__local_bh_disable)
-    sshd-4261  0d.s4   21us : sub_preempt_count (local_bh_enable)
-    sshd-4261  0d.s5   21us : sub_preempt_count (local_bh_enable)
+    bash-1994    1d..1   12us : irq_enter <-smp_apic_timer_interrupt
+    bash-1994    1d..1   12us : rcu_irq_enter <-irq_enter
+    bash-1994    1d..1   13us : add_preempt_count <-irq_enter
+    bash-1994    1d.h1   13us : exit_idle <-smp_apic_timer_interrupt
+    bash-1994    1d.h1   13us : hrtimer_interrupt <-smp_apic_timer_interrupt
+    bash-1994    1d.h1   13us : _raw_spin_lock <-hrtimer_interrupt
+    bash-1994    1d.h1   14us : add_preempt_count <-_raw_spin_lock
+    bash-1994    1d.h2   14us : ktime_get_update_offsets <-hrtimer_interrupt
 [...]
-    sshd-4261  0d.s6   41us : add_preempt_count (__local_bh_disable)
-    sshd-4261  0d.s6   42us : sub_preempt_count (local_bh_enable)
-    sshd-4261  0d.s7   42us : sub_preempt_count (local_bh_enable)
-    sshd-4261  0d.s5   43us : add_preempt_count (__local_bh_disable)
-    sshd-4261  0d.s5   43us : sub_preempt_count (local_bh_enable_ip)
-    sshd-4261  0d.s6   44us : sub_preempt_count (local_bh_enable_ip)
-    sshd-4261  0d.s5   44us : add_preempt_count (__local_bh_disable)
-    sshd-4261  0d.s5   45us : sub_preempt_count (local_bh_enable)
+    bash-1994    1d.h1   35us : lapic_next_event <-clockevents_program_event
+    bash-1994    1d.h1   35us : irq_exit <-smp_apic_timer_interrupt
+    bash-1994    1d.h1   36us : sub_preempt_count <-irq_exit
+    bash-1994    1d..2   36us : do_softirq <-irq_exit
+    bash-1994    1d..2   36us : __do_softirq <-call_softirq
+    bash-1994    1d..2   36us : __local_bh_disable <-__do_softirq
+    bash-1994    1d.s2   37us : add_preempt_count <-_raw_spin_lock_irq
+    bash-1994    1d.s3   38us : _raw_spin_unlock <-run_timer_softirq
+    bash-1994    1d.s3   39us : sub_preempt_count <-_raw_spin_unlock
+    bash-1994    1d.s2   39us : call_timer_fn <-run_timer_softirq
 [...]
-    sshd-4261  0d.s.   63us : _local_bh_enable (__do_softirq)
-    sshd-4261  0d.s1   64us : trace_preempt_on (__do_softirq)
+    bash-1994    1dNs2   81us : cpu_needs_another_gp <-rcu_process_callbacks
+    bash-1994    1dNs2   82us : __local_bh_enable <-__do_softirq
+    bash-1994    1dNs2   82us : sub_preempt_count <-__local_bh_enable
+    bash-1994    1dN.2   82us : idle_cpu <-irq_exit
+    bash-1994    1dN.2   83us : rcu_irq_exit <-irq_exit
+    bash-1994    1dN.2   83us : sub_preempt_count <-irq_exit
+    bash-1994    1.N.1   84us : _raw_spin_unlock_irqrestore <-task_rq_unlock
+    bash-1994    1.N.1   84us+: trace_preempt_on <-task_rq_unlock
+    bash-1994    1.N.1  104us : <stack trace>
+ => sub_preempt_count
+ => _raw_spin_unlock_irqrestore
+ => task_rq_unlock
+ => wake_up_new_task
+ => do_fork
+ => sys_clone
+ => stub_clone
 
 
 The above is an example of the preemptoff trace with
-ftrace_enabled set. Here we see that interrupts were disabled
+function-trace set. Here we see that interrupts were not disabled
 the entire time. The irq_enter code lets us know that we entered
 an interrupt 'h'. Before that, the functions being traced still
 show that it is not in an interrupt, but we can see from the
 functions themselves that this is not the case.
-
-Notice that __do_softirq when called does not have a
-preempt_count. It may seem that we missed a preempt enabling.
-What really happened is that the preempt count is held on the
-thread's stack and we switched to the softirq stack (4K stacks
-in effect). The code does not copy the preempt count, but
-because interrupts are disabled, we do not need to worry about
-it. Having a tracer like this is good for letting people know
-what really happens inside the kernel.
-
 
 preemptirqsoff
 --------------
···
 Again, using this trace is much like the irqsoff and preemptoff
 tracers.
 
+ # echo 0 > options/function-trace
  # echo preemptirqsoff > current_tracer
- # echo latency-format > trace_options
- # echo 0 > tracing_max_latency
  # echo 1 > tracing_on
+ # echo 0 > tracing_max_latency
  # ls -ltr
  [...]
  # echo 0 > tracing_on
  # cat trace
 # tracer: preemptirqsoff
 #
-preemptirqsoff latency trace v1.1.5 on 2.6.26-rc8
---------------------------------------------------------------------
- latency: 293 us, #3/3, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
-    -----------------
-    | task: ls-4860 (uid:0 nice:0 policy:0 rt_prio:0)
-    -----------------
- => started at: apic_timer_interrupt
- => ended at:   __do_softirq
-
-#                _------=> CPU#
-#               / _-----=> irqs-off
-#              | / _----=> need-resched
-#              || / _---=> hardirq/softirq
-#              ||| / _--=> preempt-depth
-#              |||| /
-#              |||||     delay
-#  cmd     pid ||||| time  |   caller
-#     \   /    |||||   \   |   /
-      ls-4860  0d...    0us!: trace_hardirqs_off_thunk (apic_timer_interrupt)
-      ls-4860  0d.s.  294us : _local_bh_enable (__do_softirq)
-      ls-4860  0d.s1  294us : trace_preempt_on (__do_softirq)
-
+# preemptirqsoff latency trace v1.1.5 on 3.8.0-test+
+# --------------------------------------------------------------------
+# latency: 100 us, #4/4, CPU#3 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:4)
+#    -----------------
+#    | task: ls-2230 (uid:0 nice:0 policy:0 rt_prio:0)
+#    -----------------
+#  => started at: ata_scsi_queuecmd
+#  => ended at:   ata_scsi_queuecmd
+#
+#
+#                  _------=> CPU#            
+#                 / _-----=> irqs-off        
+#                | / _----=> need-resched    
+#                || / _---=> hardirq/softirq 
+#                ||| / _--=> preempt-depth   
+#                |||| /     delay             
+#  cmd     pid   ||||| time  |   caller      
+#     \   /      |||||  \    |   /           
+      ls-2230    3d...    0us+: _raw_spin_lock_irqsave <-ata_scsi_queuecmd
+      ls-2230    3...1  100us : _raw_spin_unlock_irqrestore <-ata_scsi_queuecmd
+      ls-2230    3...1  101us+: trace_preempt_on <-ata_scsi_queuecmd
+      ls-2230    3...1  111us : <stack trace>
+ => sub_preempt_count
+ => _raw_spin_unlock_irqrestore
+ => ata_scsi_queuecmd
+ => scsi_dispatch_cmd
+ => scsi_request_fn
+ => __blk_run_queue_uncond
+ => __blk_run_queue
+ => blk_queue_bio
+ => generic_make_request
+ => submit_bio
+ => submit_bh
+ => ext3_bread
+ => ext3_dir_bread
+ => htree_dirblock_to_tree
+ => ext3_htree_fill_tree
+ => ext3_readdir
+ => vfs_readdir
+ => sys_getdents
+ => system_call_fastpath
 
 
 The trace_hardirqs_off_thunk is called from assembly on x86 when
···
 within the preemption points. We do see that it started with
 preemption enabled.
 
-Here is a trace with ftrace_enabled set:
-
+Here is a trace with function-trace set:
 
 # tracer: preemptirqsoff
 #
-preemptirqsoff latency trace v1.1.5 on 2.6.26-rc8
---------------------------------------------------------------------
- latency: 105 us, #183/183, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
-    -----------------
-    | task: sshd-4261 (uid:0 nice:0 policy:0 rt_prio:0)
-    -----------------
- => started at: write_chan
- => ended at:   __do_softirq
+# preemptirqsoff latency trace v1.1.5 on 3.8.0-test+
+# --------------------------------------------------------------------
+# latency: 161 us, #339/339, CPU#3 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:4)
+#    -----------------
+#    | task: ls-2269 (uid:0 nice:0 policy:0 rt_prio:0)
+#    -----------------
+#  => started at: schedule
+#  => ended at:   mutex_unlock
+#
+#
+#                  _------=> CPU#            
+#                 / _-----=> irqs-off        
+#                | / _----=> need-resched    
+#                || / _---=> hardirq/softirq 
+#                ||| / _--=> preempt-depth   
+#                |||| /     delay             
+#  cmd     pid   ||||| time  |   caller      
+#     \   /      |||||  \    |   /           
+kworker/-59      3...1    0us : __schedule <-schedule
+kworker/-59      3d..1    0us : rcu_preempt_qs <-rcu_note_context_switch
+kworker/-59      3d..1    1us : add_preempt_count <-_raw_spin_lock_irq
+kworker/-59      3d..2    1us : deactivate_task <-__schedule
+kworker/-59      3d..2    1us : dequeue_task <-deactivate_task
+kworker/-59      3d..2    2us : update_rq_clock <-dequeue_task
+kworker/-59      3d..2    2us : dequeue_task_fair <-dequeue_task
+kworker/-59      3d..2    2us : update_curr <-dequeue_task_fair
+kworker/-59      3d..2    2us : update_min_vruntime <-update_curr
+kworker/-59      3d..2    3us : cpuacct_charge <-update_curr
+kworker/-59      3d..2    3us : __rcu_read_lock <-cpuacct_charge
+kworker/-59      3d..2    3us : __rcu_read_unlock <-cpuacct_charge
+kworker/-59      3d..2    3us : update_cfs_rq_blocked_load <-dequeue_task_fair
+kworker/-59      3d..2    4us : clear_buddies <-dequeue_task_fair
+kworker/-59      3d..2    4us : account_entity_dequeue <-dequeue_task_fair
+kworker/-59      3d..2    4us : update_min_vruntime <-dequeue_task_fair
+kworker/-59      3d..2    4us : update_cfs_shares <-dequeue_task_fair
+kworker/-59      3d..2    5us : hrtick_update <-dequeue_task_fair
+kworker/-59      3d..2    5us : wq_worker_sleeping <-__schedule
+kworker/-59      3d..2    5us : kthread_data <-wq_worker_sleeping
+kworker/-59      3d..2    5us : put_prev_task_fair <-__schedule
+kworker/-59      3d..2    6us : pick_next_task_fair <-pick_next_task
+kworker/-59      3d..2    6us : clear_buddies <-pick_next_task_fair
+kworker/-59      3d..2    6us : set_next_entity <-pick_next_task_fair
+kworker/-59      3d..2    6us : update_stats_wait_end <-set_next_entity
+      ls-2269    3d..2    7us : finish_task_switch <-__schedule
+      ls-2269    3d..2    7us : _raw_spin_unlock_irq <-finish_task_switch
+      ls-2269    3d..2    8us : do_IRQ <-ret_from_intr
+      ls-2269    3d..2    8us : irq_enter <-do_IRQ
+      ls-2269    3d..2    8us : rcu_irq_enter <-irq_enter
+      ls-2269    3d..2    9us : add_preempt_count <-irq_enter
+      ls-2269    3d.h2    9us : exit_idle <-do_IRQ
+[...]
+      ls-2269    3d.h3   20us : sub_preempt_count <-_raw_spin_unlock
+      ls-2269    3d.h2   20us : irq_exit <-do_IRQ
+      ls-2269    3d.h2   21us : sub_preempt_count <-irq_exit
+      ls-2269    3d..3   21us : do_softirq <-irq_exit
+      ls-2269    3d..3   21us : __do_softirq <-call_softirq
+      ls-2269    3d..3   21us+: __local_bh_disable <-__do_softirq
+      ls-2269    3d.s4   29us : sub_preempt_count <-_local_bh_enable_ip
+      ls-2269    3d.s5   29us : sub_preempt_count <-_local_bh_enable_ip
+      ls-2269    3d.s5   31us : do_IRQ <-ret_from_intr
+      ls-2269    3d.s5   31us : irq_enter <-do_IRQ
+      ls-2269    3d.s5   31us : rcu_irq_enter <-irq_enter
+[...]
+      ls-2269    3d.s5   31us : rcu_irq_enter <-irq_enter
+      ls-2269    3d.s5   32us : add_preempt_count <-irq_enter
+      ls-2269    3d.H5   32us : exit_idle <-do_IRQ
+      ls-2269    3d.H5   32us : handle_irq <-do_IRQ
+      ls-2269    3d.H5   32us : irq_to_desc <-handle_irq
+      ls-2269    3d.H5   33us : handle_fasteoi_irq <-handle_irq
+[...]
+      ls-2269    3d.s5  158us : _raw_spin_unlock_irqrestore <-rtl8139_poll
+      ls-2269    3d.s3  158us : net_rps_action_and_irq_enable.isra.65 <-net_rx_action
+      ls-2269    3d.s3  159us : __local_bh_enable <-__do_softirq
+      ls-2269    3d.s3  159us : sub_preempt_count <-__local_bh_enable
+      ls-2269    3d..3  159us : idle_cpu <-irq_exit
+      ls-2269    3d..3  159us : rcu_irq_exit <-irq_exit
+      ls-2269    3d..3  160us : sub_preempt_count <-irq_exit
+      ls-2269    3d...  161us : __mutex_unlock_slowpath <-mutex_unlock
+      ls-2269    3d...  162us+: trace_hardirqs_on <-mutex_unlock
+      ls-2269    3d...  186us : <stack trace>
+ => __mutex_unlock_slowpath
+ => mutex_unlock
+ => process_output
+ => n_tty_write
+ => tty_write
+ => vfs_write
+ => sys_write
+ => system_call_fastpath
 
-#                _------=> CPU#
-#               / _-----=> irqs-off
-#              | / _----=> need-resched
-#              || / _---=> hardirq/softirq
-#              ||| / _--=> preempt-depth
-#              |||| /
-#              |||||     delay
-#  cmd     pid ||||| time  |   caller
-#     \   /    |||||   \   |   /
-      ls-4473  0.N..    0us : preempt_schedule (write_chan)
-      ls-4473  0dN.1    1us : _spin_lock (schedule)
-      ls-4473  0dN.1    2us : add_preempt_count (_spin_lock)
-      ls-4473  0d..2    2us : put_prev_task_fair (schedule)
-[...]
-      ls-4473  0d..2   13us : set_normalized_timespec (ktime_get_ts)
-      ls-4473  0d..2   13us : __switch_to (schedule)
-    sshd-4261  0d..2   14us : finish_task_switch (schedule)
-    sshd-4261  0d..2   14us : _spin_unlock_irq (finish_task_switch)
-    sshd-4261  0d..1   15us : add_preempt_count (_spin_lock_irqsave)
-    sshd-4261  0d..2   16us : _spin_unlock_irqrestore (hrtick_set)
-    sshd-4261  0d..2   16us : do_IRQ (common_interrupt)
-    sshd-4261  0d..2   17us : irq_enter (do_IRQ)
-    sshd-4261  0d..2   17us : idle_cpu (irq_enter)
-    sshd-4261  0d..2   18us : add_preempt_count (irq_enter)
-    sshd-4261  0d.h2   18us : idle_cpu (irq_enter)
-    sshd-4261  0d.h.   18us : handle_fasteoi_irq (do_IRQ)
-    sshd-4261  0d.h.   19us : _spin_lock (handle_fasteoi_irq)
-    sshd-4261  0d.h.   19us : add_preempt_count (_spin_lock)
-    sshd-4261  0d.h1   20us : _spin_unlock (handle_fasteoi_irq)
-    sshd-4261  0d.h1   20us : sub_preempt_count (_spin_unlock)
-[...]
-    sshd-4261  0d.h1   28us : _spin_unlock (handle_fasteoi_irq)
-    sshd-4261  0d.h1   29us : sub_preempt_count (_spin_unlock)
-    sshd-4261  0d.h2   29us : irq_exit (do_IRQ)
-    sshd-4261  0d.h2   29us : sub_preempt_count (irq_exit)
-    sshd-4261  0d..3   30us : do_softirq (irq_exit)
-    sshd-4261  0d...   30us : __do_softirq (do_softirq)
-    sshd-4261  0d...   31us : __local_bh_disable (__do_softirq)
-    sshd-4261  0d...   31us+: add_preempt_count (__local_bh_disable)
-    sshd-4261  0d.s4   34us : add_preempt_count (__local_bh_disable)
-[...]
-    sshd-4261  0d.s3   43us : sub_preempt_count (local_bh_enable_ip)
-    sshd-4261  0d.s4   44us : sub_preempt_count (local_bh_enable_ip)
-    sshd-4261  0d.s3   44us : smp_apic_timer_interrupt (apic_timer_interrupt)
-    sshd-4261  0d.s3   45us : irq_enter (smp_apic_timer_interrupt)
-    sshd-4261  0d.s3   45us : idle_cpu (irq_enter)
-    sshd-4261  0d.s3   46us : add_preempt_count (irq_enter)
-    sshd-4261  0d.H3   46us : idle_cpu (irq_enter)
-    sshd-4261  0d.H3   47us : hrtimer_interrupt (smp_apic_timer_interrupt)
-    sshd-4261  0d.H3   47us : ktime_get (hrtimer_interrupt)
-[...]
-    sshd-4261  0d.H3   81us : tick_program_event (hrtimer_interrupt)
-    sshd-4261  0d.H3   82us : ktime_get (tick_program_event)
-    sshd-4261  0d.H3   82us : ktime_get_ts (ktime_get)
-    sshd-4261  0d.H3   83us : getnstimeofday (ktime_get_ts)
-    sshd-4261  0d.H3   83us : set_normalized_timespec (ktime_get_ts)
-    sshd-4261  0d.H3   84us : clockevents_program_event (tick_program_event)
-    sshd-4261  0d.H3   84us : lapic_next_event (clockevents_program_event)
-    sshd-4261  0d.H3   85us : irq_exit (smp_apic_timer_interrupt)
-    sshd-4261  0d.H3   85us : sub_preempt_count (irq_exit)
-    sshd-4261  0d.s4   86us : sub_preempt_count (irq_exit)
-    sshd-4261  0d.s3   86us : add_preempt_count (__local_bh_disable)
-[...]
-    sshd-4261  0d.s1   98us : sub_preempt_count (net_rx_action)
-    sshd-4261  0d.s.   99us : add_preempt_count (_spin_lock_irq)
-    sshd-4261  0d.s1   99us+: _spin_unlock_irq (run_timer_softirq)
-    sshd-4261  0d.s.  104us : _local_bh_enable (__do_softirq)
-    sshd-4261  0d.s.  104us : sub_preempt_count (_local_bh_enable)
-    sshd-4261  0d.s.  105us : _local_bh_enable (__do_softirq)
-    sshd-4261  0d.s1  105us : trace_preempt_on (__do_softirq)
-
-
-This is a very interesting trace. It started with the preemption
-of the ls task. We see that the task had the "need_resched" bit
-set via the 'N' in the trace.  Interrupts were disabled before
-the spin_lock at the beginning of the trace. We see that a
-schedule took place to run sshd.  When the interrupts were
-enabled, we took an interrupt. On return from the interrupt
-handler, the softirq ran. We took another interrupt while
-running the softirq as we see from the capital 'H'.
+This is an interesting trace. It started with kworker running and
+scheduling out and ls taking over. But as soon as ls released the
+rq lock and enabled interrupts (but not preemption) an interrupt
+triggered. When the interrupt finished, it started running softirqs.
+But while the softirq was running, another interrupt triggered.
+When an interrupt is running inside a softirq, the annotation is 'H'.
 
 
 wakeup
 ------
+
+One common case that people are interested in tracing is the
+time it takes for a task that is woken to actually wake up.
+Now for non Real-Time tasks, this can be arbitrary. But tracing
+it none the less can be interesting. 
+
+Without function tracing:
+
+ # echo 0 > options/function-trace
+ # echo wakeup > current_tracer
+ # echo 1 > tracing_on
+ # echo 0 > tracing_max_latency
+ # chrt -f 5 sleep 1
+ # echo 0 > tracing_on
+ # cat trace
+# tracer: wakeup
+#
+# wakeup latency trace v1.1.5 on 3.8.0-test+
+# --------------------------------------------------------------------
+# latency: 15 us, #4/4, CPU#3 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:4)
+#    -----------------
+#    | task: kworker/3:1H-312 (uid:0 nice:-20 policy:0 rt_prio:0)
+#    -----------------
+#
+#                  _------=> CPU#            
+#                 / _-----=> irqs-off        
+#                | / _----=> need-resched    
+#                || / _---=> hardirq/softirq 
+#                ||| / _--=> preempt-depth   
+#                |||| /     delay             
+#  cmd     pid   ||||| time  |   caller      
+#     \   /      |||||  \    |   /           
+  <idle>-0       3dNs7    0us :      0:120:R   + [003]   312:100:R kworker/3:1H
+  <idle>-0       3dNs7    1us+: ttwu_do_activate.constprop.87 <-try_to_wake_up
+  <idle>-0       3d..3   15us : __schedule <-schedule
+  <idle>-0       3d..3   15us :      0:120:R ==> [003]   312:100:R kworker/3:1H
+
+The tracer only traces the highest priority task in the system
+to avoid tracing the normal circumstances. Here we see that
+the kworker with a nice priority of -20 (not very nice), took
+just 15 microseconds from the time it woke up, to the time it
+ran.
+
+Non Real-Time tasks are not that interesting. A more interesting
+trace is to concentrate only on Real-Time tasks.
+
+wakeup_rt
+---------
 
 In a Real-Time environment it is very important to know the
 wakeup time it takes for the highest priority task that is woken
···
 That is the longest latency it takes for something to happen,
 and not the average. We can have a very fast scheduler that may
 only have a large latency once in a while, but that would not
-work well with Real-Time tasks.  The wakeup tracer was designed
+work well with Real-Time tasks.  The wakeup_rt tracer was designed
 to record the worst case wakeups of RT tasks. Non-RT tasks are
 not recorded because the tracer only records one worst case and
 tracing non-RT tasks that are unpredictable will overwrite the
-worst case latency of RT tasks.
+worst case latency of RT tasks (just run the normal wakeup
+tracer for a while to see that effect).
 
 Since this tracer only deals with RT tasks, we will run this
 slightly differently than we did with the previous tracers.
 Instead of performing an 'ls', we will run 'sleep 1' under
 'chrt' which changes the priority of the task.
 
- # echo wakeup > current_tracer
- # echo latency-format > trace_options
- # echo 0 > tracing_max_latency
+ # echo 0 > options/function-trace
+ # echo wakeup_rt > current_tracer
  # echo 1 > tracing_on
+ # echo 0 > tracing_max_latency
  # chrt -f 5 sleep 1
  # echo 0 > tracing_on
  # cat trace
 # tracer: wakeup
 #
-wakeup latency trace v1.1.5 on 2.6.26-rc8
---------------------------------------------------------------------
- latency: 4 us, #2/2, CPU#1 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
-    -----------------
-    | task: sleep-4901 (uid:0 nice:0 policy:1 rt_prio:5)
-    -----------------
+# tracer: wakeup_rt
+#
+# wakeup_rt latency trace v1.1.5 on 3.8.0-test+
+# --------------------------------------------------------------------
+# latency: 5 us, #4/4, CPU#3 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:4)
+#    -----------------
+#    | task: sleep-2389 (uid:0 nice:0 policy:1 rt_prio:5)
+#    -----------------
+#
+#                  _------=> CPU#            
+#                 / _-----=> irqs-off        
+#                | / _----=> need-resched    
+#                || / _---=> hardirq/softirq 
+#                ||| / _--=> preempt-depth   
+#                |||| /     delay             
+#  cmd     pid   ||||| time  |   caller      
+#     \   /      |||||  \    |   /           
+  <idle>-0       3d.h4    0us :      0:120:R   + [003]  2389: 94:R sleep
+  <idle>-0       3d.h4    1us+: ttwu_do_activate.constprop.87 <-try_to_wake_up
+  <idle>-0       3d..3    5us : __schedule <-schedule
+  <idle>-0       3d..3    5us :      0:120:R ==> [003]  2389: 94:R sleep
 
-#                _------=> CPU#
-#               / _-----=> irqs-off
-#              | / _----=> need-resched
-#              || / _---=> hardirq/softirq
-#              ||| / _--=> preempt-depth
-#              |||| /
-#              |||||     delay
-#  cmd     pid ||||| time  |   caller
-#     \   /    |||||   \   |   /
-  <idle>-0     1d.h4    0us+: try_to_wake_up (wake_up_process)
-  <idle>-0     1d..4    4us : schedule (cpu_idle)
 
+Running this on an idle system, we see that it only took 5 microseconds
+to perform the task switch.  Note, since the trace point in the schedule
+is before the actual "switch", we stop the tracing when the recorded task
+is about to schedule in. This may change if we add a new marker at the
+end of the scheduler.
 
-Running this on an idle system, we see that it only took 4
-microseconds to perform the task switch.  Note, since the trace
-marker in the schedule is before the actual "switch", we stop
-the tracing when the recorded task is about to schedule in. This
-may change if we add a new marker at the end of the scheduler.
-
-Notice that the recorded task is 'sleep' with the PID of 4901
+Notice that the recorded task is 'sleep' with the PID of 2389
 and it has an rt_prio of 5. This priority is user-space priority
 and not the internal kernel priority. The policy is 1 for
 SCHED_FIFO and 2 for SCHED_RR.
 
-Doing the same with chrt -r 5 and ftrace_enabled set.
+Note, that the trace data shows the internal priority (99 - rtprio).
 
-# tracer: wakeup
+  <idle>-0       3d..3    5us :      0:120:R ==> [003]  2389: 94:R sleep
+
+The 0:120:R means idle was running with a nice priority of 0 (120 - 20)
+and in the running state 'R'. The sleep task was scheduled in with
+2389: 94:R. That is the priority is the kernel rtprio (99 - 5 = 94)
+and it too is in the running state.
+
+Doing the same with chrt -r 5 and function-trace set.
+
+  echo 1 > options/function-trace
+
+# tracer: wakeup_rt
 #
-wakeup latency trace v1.1.5 on 2.6.26-rc8
---------------------------------------------------------------------
- latency: 50 us, #60/60, CPU#1 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
-    -----------------
-    | task: sleep-4068 (uid:0 nice:0 policy:2 rt_prio:5)
-    -----------------
+# wakeup_rt latency trace v1.1.5 on 3.8.0-test+
+# --------------------------------------------------------------------
+# latency: 29 us, #85/85, CPU#3 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:4)
+#    -----------------
+#    | task: sleep-2448 (uid:0 nice:0 policy:1 rt_prio:5)
+#    -----------------
+#
+#                  _------=> CPU#            
+#                 / _-----=> irqs-off        
+#                | / _----=> need-resched    
+#                || / _---=> hardirq/softirq 
+#                ||| / _--=> preempt-depth   
+#                |||| /     delay             
+#  cmd     pid   ||||| time  |   caller      
+#     \   /      |||||  \    |   /           
+  <idle>-0       3d.h4    1us+:      0:120:R   + [003]  2448: 94:R sleep
+  <idle>-0       3d.h4    2us : ttwu_do_activate.constprop.87 <-try_to_wake_up
+  <idle>-0       3d.h3    3us : check_preempt_curr <-ttwu_do_wakeup
+  <idle>-0       3d.h3    3us : resched_task <-check_preempt_curr
+  <idle>-0       3dNh3    4us : task_woken_rt <-ttwu_do_wakeup
+  <idle>-0       3dNh3    4us : _raw_spin_unlock <-try_to_wake_up
+  <idle>-0       3dNh3    4us : sub_preempt_count <-_raw_spin_unlock
+  <idle>-0       3dNh2    5us : ttwu_stat <-try_to_wake_up
+  <idle>-0       3dNh2    5us : _raw_spin_unlock_irqrestore <-try_to_wake_up
+  <idle>-0       3dNh2    6us : sub_preempt_count <-_raw_spin_unlock_irqrestore
+  <idle>-0       3dNh1    6us : _raw_spin_lock <-__run_hrtimer
+  <idle>-0       3dNh1    6us : add_preempt_count <-_raw_spin_lock
+  <idle>-0       3dNh2    7us : _raw_spin_unlock <-hrtimer_interrupt
+  <idle>-0       3dNh2    7us : sub_preempt_count <-_raw_spin_unlock
+  <idle>-0       3dNh1    7us : tick_program_event <-hrtimer_interrupt
+  <idle>-0       3dNh1    7us : clockevents_program_event <-tick_program_event
+  <idle>-0       3dNh1    8us : ktime_get <-clockevents_program_event
+  <idle>-0       3dNh1    8us : lapic_next_event <-clockevents_program_event
+  <idle>-0       3dNh1    8us : irq_exit <-smp_apic_timer_interrupt
+  <idle>-0       3dNh1    9us : sub_preempt_count <-irq_exit
+  <idle>-0       3dN.2    9us : idle_cpu <-irq_exit
+  <idle>-0       3dN.2    9us : rcu_irq_exit <-irq_exit
+  <idle>-0       3dN.2   10us : rcu_eqs_enter_common.isra.45 <-rcu_irq_exit
+  <idle>-0       3dN.2   10us : sub_preempt_count <-irq_exit
+  <idle>-0       3.N.1   11us : rcu_idle_exit <-cpu_idle
+  <idle>-0       3dN.1   11us : rcu_eqs_exit_common.isra.43 <-rcu_idle_exit
+  <idle>-0       3.N.1   11us : tick_nohz_idle_exit <-cpu_idle
+  <idle>-0       3dN.1   12us : menu_hrtimer_cancel <-tick_nohz_idle_exit
+  <idle>-0       3dN.1   12us : ktime_get <-tick_nohz_idle_exit
+  <idle>-0       3dN.1   12us : tick_do_update_jiffies64 <-tick_nohz_idle_exit
+  <idle>-0       3dN.1   13us : update_cpu_load_nohz <-tick_nohz_idle_exit
+  <idle>-0       3dN.1   13us : _raw_spin_lock <-update_cpu_load_nohz
+  <idle>-0       3dN.1   13us : add_preempt_count <-_raw_spin_lock
+  <idle>-0       3dN.2   13us : __update_cpu_load <-update_cpu_load_nohz
+  <idle>-0       3dN.2   14us : sched_avg_update <-__update_cpu_load
+  <idle>-0       3dN.2   14us : _raw_spin_unlock <-update_cpu_load_nohz
+  <idle>-0       3dN.2   14us : sub_preempt_count <-_raw_spin_unlock
+  <idle>-0       3dN.1   15us : calc_load_exit_idle <-tick_nohz_idle_exit
+  <idle>-0       3dN.1   15us : touch_softlockup_watchdog <-tick_nohz_idle_exit
+  <idle>-0       3dN.1   15us : hrtimer_cancel <-tick_nohz_idle_exit
+  <idle>-0       3dN.1   15us : hrtimer_try_to_cancel <-hrtimer_cancel
+  <idle>-0       3dN.1   16us : lock_hrtimer_base.isra.18 <-hrtimer_try_to_cancel
+  <idle>-0       3dN.1   16us : _raw_spin_lock_irqsave <-lock_hrtimer_base.isra.18
+  <idle>-0       3dN.1   16us : add_preempt_count <-_raw_spin_lock_irqsave
+  <idle>-0       3dN.2   17us : __remove_hrtimer <-remove_hrtimer.part.16
+  <idle>-0       3dN.2   17us : hrtimer_force_reprogram <-__remove_hrtimer
+  <idle>-0       3dN.2   17us : tick_program_event <-hrtimer_force_reprogram
+  <idle>-0       3dN.2   18us : clockevents_program_event <-tick_program_event
+  <idle>-0       3dN.2   18us : ktime_get <-clockevents_program_event
+  <idle>-0       3dN.2   18us : lapic_next_event <-clockevents_program_event
+  <idle>-0       3dN.2   19us : _raw_spin_unlock_irqrestore <-hrtimer_try_to_cancel
+  <idle>-0       3dN.2   19us : sub_preempt_count <-_raw_spin_unlock_irqrestore
+  <idle>-0       3dN.1   19us : hrtimer_forward <-tick_nohz_idle_exit
+  <idle>-0       3dN.1   20us : ktime_add_safe <-hrtimer_forward
+  <idle>-0       3dN.1   20us : ktime_add_safe <-hrtimer_forward
+  <idle>-0       3dN.1   20us : hrtimer_start_range_ns <-hrtimer_start_expires.constprop.11
+  <idle>-0       3dN.1   20us : __hrtimer_start_range_ns <-hrtimer_start_range_ns
+  <idle>-0       3dN.1   21us : lock_hrtimer_base.isra.18 <-__hrtimer_start_range_ns
+  <idle>-0       3dN.1   21us : _raw_spin_lock_irqsave <-lock_hrtimer_base.isra.18
+  <idle>-0       3dN.1   21us : add_preempt_count <-_raw_spin_lock_irqsave
+  <idle>-0       3dN.2   22us : ktime_add_safe <-__hrtimer_start_range_ns
+  <idle>-0       3dN.2   22us : enqueue_hrtimer <-__hrtimer_start_range_ns
+  <idle>-0       3dN.2   22us : tick_program_event <-__hrtimer_start_range_ns
+  <idle>-0       3dN.2   23us : clockevents_program_event <-tick_program_event
+  <idle>-0       3dN.2   23us : ktime_get <-clockevents_program_event
+  <idle>-0       3dN.2   23us : lapic_next_event <-clockevents_program_event
+  <idle>-0       3dN.2   24us : _raw_spin_unlock_irqrestore <-__hrtimer_start_range_ns
+  <idle>-0       3dN.2   24us : sub_preempt_count <-_raw_spin_unlock_irqrestore
+  <idle>-0       3dN.1   24us : account_idle_ticks <-tick_nohz_idle_exit
+  <idle>-0       3dN.1   24us : account_idle_time <-account_idle_ticks
+  <idle>-0       3.N.1   25us : sub_preempt_count <-cpu_idle
+  <idle>-0       3.N..   25us : schedule <-cpu_idle
+  <idle>-0       3.N..   25us : __schedule <-preempt_schedule
+  <idle>-0       3.N..   26us : add_preempt_count <-__schedule
+  <idle>-0       3.N.1   26us : rcu_note_context_switch <-__schedule
+  <idle>-0       3.N.1   26us : rcu_sched_qs <-rcu_note_context_switch
+  <idle>-0       3dN.1   27us : rcu_preempt_qs <-rcu_note_context_switch
+  <idle>-0       3.N.1   27us : _raw_spin_lock_irq <-__schedule
+  <idle>-0       3dN.1   27us : add_preempt_count <-_raw_spin_lock_irq
+  <idle>-0       3dN.2   28us : put_prev_task_idle <-__schedule
+  <idle>-0       3dN.2   28us : pick_next_task_stop <-pick_next_task
+  <idle>-0       3dN.2   28us : pick_next_task_rt <-pick_next_task
+  <idle>-0       3dN.2   29us : dequeue_pushable_task <-pick_next_task_rt
+  <idle>-0       3d..3   29us : __schedule <-preempt_schedule
+  <idle>-0       3d..3   30us :      0:120:R ==> [003]  2448: 94:R sleep
 
-#                _------=> CPU#
-#               / _-----=> irqs-off
-#              | / _----=> need-resched
-#              || / _---=> hardirq/softirq
-#              ||| / _--=> preempt-depth
-#              |||| /
-#              |||||     delay
-#  cmd     pid ||||| time  |   caller
-#     \   /    |||||   \   |   /
-ksoftirq-7     1d.H3    0us : try_to_wake_up (wake_up_process)
-ksoftirq-7     1d.H4    1us : sub_preempt_count (marker_probe_cb)
-ksoftirq-7     1d.H3    2us : check_preempt_wakeup (try_to_wake_up)
-ksoftirq-7     1d.H3    3us : update_curr (check_preempt_wakeup)
-ksoftirq-7     1d.H3    4us : calc_delta_mine (update_curr)
-ksoftirq-7     1d.H3    5us : __resched_task (check_preempt_wakeup)
-ksoftirq-7     1d.H3    6us : task_wake_up_rt (try_to_wake_up)
-ksoftirq-7     1d.H3    7us : _spin_unlock_irqrestore (try_to_wake_up)
-[...]
-ksoftirq-7     1d.H2   17us : irq_exit (smp_apic_timer_interrupt)
-ksoftirq-7     1d.H2   18us : sub_preempt_count (irq_exit)
-ksoftirq-7     1d.s3   19us : sub_preempt_count (irq_exit)
-ksoftirq-7     1..s2   20us : rcu_process_callbacks (__do_softirq)
-[...]
-ksoftirq-7     1..s2   26us : __rcu_process_callbacks (rcu_process_callbacks)
-ksoftirq-7     1d.s2   27us : _local_bh_enable (__do_softirq)
-ksoftirq-7     1d.s2   28us : sub_preempt_count (_local_bh_enable)
-ksoftirq-7     1.N.3   29us : sub_preempt_count (ksoftirqd)
-ksoftirq-7     1.N.2   30us : _cond_resched (ksoftirqd)
-ksoftirq-7     1.N.2   31us : __cond_resched (_cond_resched)
-ksoftirq-7     1.N.2   32us : add_preempt_count (__cond_resched)
-ksoftirq-7     1.N.2   33us : schedule (__cond_resched)
-ksoftirq-7     1.N.2   33us : add_preempt_count (schedule)
-ksoftirq-7     1.N.3   34us : hrtick_clear (schedule)
-ksoftirq-7     1dN.3   35us : _spin_lock (schedule)
-ksoftirq-7     1dN.3   36us : add_preempt_count (_spin_lock)
-ksoftirq-7     1d..4   37us : put_prev_task_fair (schedule)
-ksoftirq-7     1d..4   38us : update_curr (put_prev_task_fair)
-[...]
-ksoftirq-7     1d..5   47us : _spin_trylock (tracing_record_cmdline)
-ksoftirq-7     1d..5   48us : add_preempt_count (_spin_trylock)
-ksoftirq-7     1d..6   49us : _spin_unlock (tracing_record_cmdline)
-ksoftirq-7     1d..6   49us : sub_preempt_count (_spin_unlock)
-ksoftirq-7     1d..4   50us : schedule (__cond_resched)
+This isn't that big of a trace, even with function tracing enabled,
+so I included the entire trace.
 
-The interrupt went off while running ksoftirqd. This task runs
-at SCHED_OTHER. Why did not we see the 'N' set early? This may
-be a harmless bug with x86_32 and 4K stacks. On x86_32 with 4K
-stacks configured, the interrupt and softirq run with their own
-stack. Some information is held on the top of the task's stack
-(need_resched and preempt_count are both stored there). The
-setting of the NEED_RESCHED bit is done directly to the task's
-stack, but the reading of the NEED_RESCHED is done by looking at
-the current stack, which in this case is the stack for the hard
-interrupt. This hides the fact that NEED_RESCHED has been set.
-We do not see the 'N' until we switch back to the task's
-assigned stack.
+The interrupt went off while when the system was idle. Somewhere
+before task_woken_rt() was called, the NEED_RESCHED flag was set,
+this is indicated by the first occurrence of the 'N' flag.
+
+Latency tracing and events
+--------------------------
+As function tracing can induce a much larger latency, but without
+seeing what happens within the latency it is hard to know what
+caused it. There is a middle ground, and that is with enabling
+events.
+
+ # echo 0 > options/function-trace
+ # echo wakeup_rt > current_tracer
+ # echo 1 > events/enable
+ # echo 1 > tracing_on
+ # echo 0 > tracing_max_latency
+ # chrt -f 5 sleep 1
+ # echo 0 > tracing_on
+ # cat trace
+# tracer: wakeup_rt
+#
+# wakeup_rt latency trace v1.1.5 on 3.8.0-test+
+# --------------------------------------------------------------------
+# latency: 6 us, #12/12, CPU#2 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:4)
+#    -----------------
+#    | task: sleep-5882 (uid:0 nice:0 policy:1 rt_prio:5)
+#    -----------------
+#
+#                  _------=> CPU#            
+#                 / _-----=> irqs-off        
+#                | / _----=> need-resched    
+#                || / _---=> hardirq/softirq 
+#                ||| / _--=> preempt-depth   
+#                |||| /     delay             
+#  cmd     pid   ||||| time  |   caller      
+#     \   /      |||||  \    |   /           
+  <idle>-0       2d.h4    0us :      0:120:R   + [002]  5882: 94:R sleep
+  <idle>-0       2d.h4    0us : ttwu_do_activate.constprop.87 <-try_to_wake_up
+  <idle>-0       2d.h4    1us : sched_wakeup: comm=sleep pid=5882 prio=94 success=1 target_cpu=002
+  <idle>-0       2dNh2    1us : hrtimer_expire_exit: hrtimer=ffff88007796feb8
+  <idle>-0       2.N.2    2us : power_end: cpu_id=2
+  <idle>-0       2.N.2    3us : cpu_idle: state=4294967295 cpu_id=2
+  <idle>-0       2dN.3    4us : hrtimer_cancel: hrtimer=ffff88007d50d5e0
+  <idle>-0       2dN.3    4us : hrtimer_start: hrtimer=ffff88007d50d5e0 function=tick_sched_timer expires=34311211000000 softexpires=34311211000000
+  <idle>-0       2.N.2    5us : rcu_utilization: Start context switch
+  <idle>-0       2.N.2    5us : rcu_utilization: End context switch
+  <idle>-0       2d..3    6us : __schedule <-schedule
+  <idle>-0       2d..3    6us :      0:120:R ==> [002]  5882: 94:R sleep
+
 
 function
 --------
···
 This tracer is the function tracer. Enabling the function tracer
 can be done from the debug file system. Make sure the
 ftrace_enabled is set; otherwise this tracer is a nop.
+See the "ftrace_enabled" section below.
 
  # sysctl kernel.ftrace_enabled=1
  # echo function > current_tracer
···
  # cat trace
 # tracer: function
 #
-#           TASK-PID   CPU#    TIMESTAMP  FUNCTION
-#              | |      |          |         |
-            bash-4003  [00]   123.638713: finish_task_switch <-schedule
-            bash-4003  [00]   123.638714: _spin_unlock_irq <-finish_task_switch
-            bash-4003  [00]   123.638714: sub_preempt_count <-_spin_unlock_irq
-            bash-4003  [00]   123.638715: hrtick_set <-schedule
-            bash-4003  [00]   123.638715: _spin_lock_irqsave <-hrtick_set
-            bash-4003  [00]   123.638716: add_preempt_count <-_spin_lock_irqsave
-            bash-4003  [00]   123.638716: _spin_unlock_irqrestore <-hrtick_set
-            bash-4003  [00]   123.638717: sub_preempt_count <-_spin_unlock_irqrestore
-            bash-4003  [00]   123.638717: hrtick_clear <-hrtick_set
-            bash-4003  [00]   123.638718: sub_preempt_count <-schedule
-            bash-4003  [00]   123.638718: sub_preempt_count <-preempt_schedule
-            bash-4003  [00]   123.638719: wait_for_completion <-__stop_machine_run
-            bash-4003  [00]   123.638719: wait_for_common <-wait_for_completion
-            bash-4003  [00]   123.638720: _spin_lock_irq <-wait_for_common
-            bash-4003  [00]   123.638720: add_preempt_count <-_spin_lock_irq
+# entries-in-buffer/entries-written: 24799/24799   #P:4
+#
+#                              _-----=> irqs-off
+#                             / _----=> need-resched
+#                            | / _---=> hardirq/softirq
+#                            || / _--=> preempt-depth
+#                            ||| /     delay
+#           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
+#              | |       |   ||||       |         |
+            bash-1994  [002] ....  3082.063030: mutex_unlock <-rb_simple_write
+            bash-1994  [002] ....  3082.063031: __mutex_unlock_slowpath <-mutex_unlock
+            bash-1994  [002] ....  3082.063031: __fsnotify_parent <-fsnotify_modify
+            bash-1994  [002] ....  3082.063032: fsnotify <-fsnotify_modify
+            bash-1994  [002] ....  3082.063032: __srcu_read_lock <-fsnotify
+            bash-1994  [002] ....  3082.063032: add_preempt_count <-__srcu_read_lock
+            bash-1994  [002] ...1  3082.063032: sub_preempt_count <-__srcu_read_lock
+            bash-1994  [002] ....  3082.063033: __srcu_read_unlock <-fsnotify
 [...]
 
 
···
         return 0;
 }
 
+Or this simple script!
 
-hw-branch-tracer (x86 only)
----------------------------
+------
+#!/bin/bash
 
-This tracer uses the x86 last branch tracing hardware feature to
-collect a branch trace on all cpus with relatively low overhead.
-
-The tracer uses a fixed-size circular buffer per cpu and only
-traces ring 0 branches. The trace file dumps that buffer in the
-following format:
-
-# tracer: hw-branch-tracer
-#
-# CPU#        TO  <-  FROM
-   0  scheduler_tick+0xb5/0x1bf	  <-  task_tick_idle+0x5/0x6
-   2  run_posix_cpu_timers+0x2b/0x72a	  <-  run_posix_cpu_timers+0x25/0x72a
-   0  scheduler_tick+0x139/0x1bf	  <-  scheduler_tick+0xed/0x1bf
-   0  scheduler_tick+0x17c/0x1bf	  <-  scheduler_tick+0x148/0x1bf
-   2  run_posix_cpu_timers+0x9e/0x72a	  <-  run_posix_cpu_timers+0x5e/0x72a
-   0  scheduler_tick+0x1b6/0x1bf	  <-  scheduler_tick+0x1aa/0x1bf
-
-
-The tracer may be used to dump the trace for the oops'ing cpu on
-a kernel oops into the system log. To enable this,
-ftrace_dump_on_oops must be set. To set ftrace_dump_on_oops, one
-can either use the sysctl function or set it via the proc system
-interface.
-
-  sysctl kernel.ftrace_dump_on_oops=n
-
-or
-
-  echo n > /proc/sys/kernel/ftrace_dump_on_oops
-
-If n = 1, ftrace will dump buffers of all CPUs, if n = 2 ftrace will
-only dump the buffer of the CPU that triggered the oops.
-
-Here's an example of such a dump after a null pointer
-dereference in a kernel module:
-
-[57848.105921] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
-[57848.106019] IP: [<ffffffffa0000006>] open+0x6/0x14 [oops]
-[57848.106019] PGD 2354e9067 PUD 2375e7067 PMD 0
-[57848.106019] Oops: 0002 [#1] SMP
-[57848.106019] last sysfs file: /sys/devices/pci0000:00/0000:00:1e.0/0000:20:05.0/local_cpus
-[57848.106019] Dumping ftrace buffer:
-[57848.106019] ---------------------------------
-[...]
-[57848.106019]    0  chrdev_open+0xe6/0x165	  <-  cdev_put+0x23/0x24
-[57848.106019]    0  chrdev_open+0x117/0x165	  <-  chrdev_open+0xfa/0x165
-[57848.106019]    0  chrdev_open+0x120/0x165	  <-  chrdev_open+0x11c/0x165
-[57848.106019]    0  chrdev_open+0x134/0x165	  <-  chrdev_open+0x12b/0x165
-[57848.106019]    0  open+0x0/0x14 [oops]	  <-  chrdev_open+0x144/0x165
-[57848.106019]    0  page_fault+0x0/0x30	  <-  open+0x6/0x14 [oops]
-[57848.106019]    0  error_entry+0x0/0x5b	  <-  page_fault+0x4/0x30
-[57848.106019]    0  error_kernelspace+0x0/0x31	  <-  error_entry+0x59/0x5b
-[57848.106019]    0  error_sti+0x0/0x1	  <-  error_kernelspace+0x2d/0x31
-[57848.106019]    0  page_fault+0x9/0x30	  <-  error_sti+0x0/0x1
-[57848.106019]    0  do_page_fault+0x0/0x881	  <-  page_fault+0x1a/0x30
-[...]
-[57848.106019]    0  do_page_fault+0x66b/0x881	  <-  is_prefetch+0x1ee/0x1f2
-[57848.106019]    0  do_page_fault+0x6e0/0x881	  <-  do_page_fault+0x67a/0x881
-[57848.106019]    0  oops_begin+0x0/0x96	  <-  do_page_fault+0x6e0/0x881
-[57848.106019]    0  trace_hw_branch_oops+0x0/0x2d	  <-  oops_begin+0x9/0x96
-[...]
-[57848.106019]    0  ds_suspend_bts+0x2a/0xe3	  <-  ds_suspend_bts+0x1a/0xe3
-[57848.106019] ---------------------------------
-[57848.106019] CPU 0
-[57848.106019] Modules linked in: oops
-[57848.106019] Pid: 5542, comm: cat Tainted: G        W  2.6.28 #23
-[57848.106019] RIP: 0010:[<ffffffffa0000006>]  [<ffffffffa0000006>] open+0x6/0x14 [oops]
-[57848.106019] RSP: 0018:ffff880235457d48  EFLAGS: 00010246
-[...]
+debugfs=`sed -ne 's/^debugfs \(.*\) debugfs.*/\1/p' /proc/mounts`
+echo nop > $debugfs/tracing/current_tracer
+echo 0 > $debugfs/tracing/tracing_on
+echo $$ > $debugfs/tracing/set_ftrace_pid
+echo function > $debugfs/tracing/current_tracer
+echo 1 > $debugfs/tracing/tracing_on
+exec "$@"
+------
 
 
 function graph tracer
···
 include the -pg switch in the compiling of the kernel.)
 
 At compile time every C file object is run through the
-recordmcount.pl script (located in the scripts directory). This
-script will process the C object using objdump to find all the
-locations in the .text section that call mcount. (Note, only the
-.text section is processed, since processing other sections like
-.init.text may cause races due to those sections being freed).
+recordmcount program (located in the scripts directory). This
+program will parse the ELF headers in the C object to find all
+the locations in the .text section that call mcount. (Note, only
+white listed .text sections are processed, since processing other
+sections like .init.text may cause races due to those sections
+being freed unexpectedly).
 
 A new section called "__mcount_loc" is created that holds
 references to all the mcount call sites in the .text section.
-This section is compiled back into the original object. The
-final linker will add all these references into a single table.
+The recordmcount program re-links this section back into the
+original object. The final linking stage of the kernel will add all these
+references into a single table.
 
 On boot up, before SMP is initialized, the dynamic ftrace code
 scans this table and updates all the locations into nops. It
···
 list. This is automatic in the module unload code, and the
 module author does not need to worry about it.
 
-When tracing is enabled, kstop_machine is called to prevent
-races with the CPUS executing code being modified (which can
-cause the CPU to do undesirable things), and the nops are
+When tracing is enabled, the process of modifying the function
+tracepoints is dependent on architecture. The old method is to use
+kstop_machine to prevent races with the CPUs executing code being
+modified (which can cause the CPU to do undesirable things, especially
+if the modified code crosses cache (or page) boundaries), and the nops are
 patched back to calls. But this time, they do not call mcount
 (which is just a function stub). They now call into the ftrace
 infrastructure.
+
+The new method of modifying the function tracepoints is to place
+a breakpoint at the location to be modified, sync all CPUs, modify
+the rest of the instruction not covered by the breakpoint. Sync
+all CPUs again, and then remove the breakpoint with the finished
+version to the ftrace call site.
+
+Some archs do not even need to monkey around with the synchronization,
+and can just slap the new code on top of the old without any
+problems with other CPUs executing it at the same time.
 
 One special side-effect to the recording of the functions being
 traced is that we can now selectively choose which functions we
···
 
 If I am only interested in sys_nanosleep and hrtimer_interrupt:
 
- # echo sys_nanosleep hrtimer_interrupt \
-		> set_ftrace_filter
+ # echo sys_nanosleep hrtimer_interrupt > set_ftrace_filter
  # echo function > current_tracer
  # echo 1 > tracing_on
  # usleep 1
  # echo 0 > tracing_on
  # cat trace
-# tracer: ftrace
+# tracer: function
 #
-#           TASK-PID   CPU#    TIMESTAMP  FUNCTION
-#              | |      |          |         |
-          usleep-4134  [00]  1317.070017: hrtimer_interrupt <-smp_apic_timer_interrupt
-          usleep-4134  [00]  1317.070111: sys_nanosleep <-syscall_call
-          <idle>-0     [00]  1317.070115: hrtimer_interrupt <-smp_apic_timer_interrupt
+# entries-in-buffer/entries-written: 5/5   #P:4
+#
+#                              _-----=> irqs-off
+#                             / _----=> need-resched
+#                            | / _---=> hardirq/softirq
+#                            || / _--=> preempt-depth
+#                            ||| /     delay
+#           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
+#              | |       |   ||||       |         |
+          usleep-2665  [001] ....  4186.475355: sys_nanosleep <-system_call_fastpath
+          <idle>-0     [001] d.h1  4186.475409: hrtimer_interrupt <-smp_apic_timer_interrupt
+          usleep-2665  [001] d.h1  4186.475426: hrtimer_interrupt <-smp_apic_timer_interrupt
+          <idle>-0     [003] d.h1  4186.475426: hrtimer_interrupt <-smp_apic_timer_interrupt
+          <idle>-0     [002] d.h1  4186.475427: hrtimer_interrupt <-smp_apic_timer_interrupt
 
 To see which functions are being traced, you can cat the file:
 
···
 
 Produces:
 
-# tracer: ftrace
+# tracer: function
 #
-#           TASK-PID   CPU#    TIMESTAMP  FUNCTION
-#              | |      |          |         |
-            bash-4003  [00]  1480.611794: hrtimer_init <-copy_process
-            bash-4003  [00]  1480.611941: hrtimer_start <-hrtick_set
-            bash-4003  [00]  1480.611956: hrtimer_cancel <-hrtick_clear
-            bash-4003  [00]  1480.611956: hrtimer_try_to_cancel <-hrtimer_cancel
-          <idle>-0     [00]  1480.612019: hrtimer_get_next_event <-get_next_timer_interrupt
-          <idle>-0     [00]  1480.612025: hrtimer_get_next_event <-get_next_timer_interrupt
-          <idle>-0     [00]  1480.612032: hrtimer_get_next_event <-get_next_timer_interrupt
-          <idle>-0     [00]  1480.612037: hrtimer_get_next_event <-get_next_timer_interrupt
-          <idle>-0     [00]  1480.612382: hrtimer_get_next_event <-get_next_timer_interrupt
-
+# entries-in-buffer/entries-written: 897/897   #P:4
+#
+#                              _-----=> irqs-off
+#                             / _----=> need-resched
+#                            | / _---=> hardirq/softirq
+#                            || / _--=> preempt-depth
+#                            ||| /     delay
+#           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
+#              | |       |   ||||       |         |
+          <idle>-0     [003] dN.1  4228.547803: hrtimer_cancel <-tick_nohz_idle_exit
+          <idle>-0     [003] dN.1  4228.547804: hrtimer_try_to_cancel <-hrtimer_cancel
+          <idle>-0     [003] dN.2  4228.547805: hrtimer_force_reprogram <-__remove_hrtimer
+          <idle>-0     [003] dN.1  4228.547805: hrtimer_forward <-tick_nohz_idle_exit
+          <idle>-0     [003] dN.1  4228.547805: hrtimer_start_range_ns <-hrtimer_start_expires.constprop.11
+          <idle>-0     [003] d..1  4228.547858: hrtimer_get_next_event <-get_next_timer_interrupt
+          <idle>-0     [003] d..1  4228.547859: hrtimer_start <-__tick_nohz_idle_enter
+          <idle>-0     [003] d..2  4228.547860: hrtimer_force_reprogram <-__rem
 
 Notice that we lost the sys_nanosleep.
 
···
 
 Produces:
 
-# tracer: ftrace
+# tracer: function
 #
-#           TASK-PID   CPU#    TIMESTAMP  FUNCTION
-#              | |      |          |         |
-            bash-4043  [01]   115.281644: finish_task_switch <-schedule
-            bash-4043  [01]   115.281645: hrtick_set <-schedule
-            bash-4043  [01]   115.281645: hrtick_clear <-hrtick_set
-            bash-4043  [01]   115.281646: wait_for_completion <-__stop_machine_run
-            bash-4043  [01]   115.281647: wait_for_common <-wait_for_completion
-            bash-4043  [01]   115.281647: kthread_stop <-stop_machine_run
-            bash-4043  [01]   115.281648: init_waitqueue_head <-kthread_stop
-            bash-4043  [01]   115.281648: wake_up_process <-kthread_stop
-            bash-4043  [01]   115.281649: try_to_wake_up <-wake_up_process
+# entries-in-buffer/entries-written: 39608/39608   #P:4
+#
+#                              _-----=> irqs-off
+#                             / _----=> need-resched
+#                            | / _---=> hardirq/softirq
+#                            || / _--=> preempt-depth
+#                            ||| /     delay
+#           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
+#              | |       |   ||||       |         |
+            bash-1994  [000] ....  4342.324896: file_ra_state_init <-do_dentry_open
+            bash-1994  [000] ....  4342.324897: open_check_o_direct <-do_last
+            bash-1994  [000] ....  4342.324897: ima_file_check <-do_last
+            bash-1994  [000] ....  4342.324898: process_measurement <-ima_file_check
+            bash-1994  [000] ....  4342.324898: ima_get_action <-process_measurement
+            bash-1994  [000] ....  4342.324898: ima_match_policy <-ima_get_action
+            bash-1994  [000] ....  4342.324899: do_truncate <-do_last
+            bash-1994  [000] ....  4342.324899: should_remove_suid <-do_truncate
+            bash-1994  [000] ....  4342.324899: notify_change <-do_truncate
+            bash-1994  [000] ....  4342.324900: current_fs_time <-notify_change
+            bash-1994  [000] ....  4342.324900: current_kernel_time <-current_fs_time
+            bash-1994  [000] ....  4342.324900: timespec_trunc <-current_fs_time
 
 We can see that there's no more lock or preempt tracing.
 
···
  echo > set_graph_function
 
 
+ftrace_enabled
+--------------
+
+Note, the proc sysctl ftrace_enable is a big on/off switch for the
+function tracer. By default it is enabled (when function tracing is
+enabled in the kernel). If it is disabled, all function tracing is
+disabled. This includes not only the function tracers for ftrace, but
+also for any other uses (perf, kprobes, stack tracing, profiling, etc).
+
+Please disable this with care.
+
+This can be disable (and enabled) with:
+
+  sysctl kernel.ftrace_enabled=0
+  sysctl kernel.ftrace_enabled=1
+
+ or
+
+  echo 0 > /proc/sys/kernel/ftrace_enabled
+  echo 1 > /proc/sys/kernel/ftrace_enabled
+
+
 Filter commands
 ---------------
 
···
 
    echo '__schedule_bug:traceoff:5' > set_ftrace_filter
 
+  To always disable tracing when __schedule_bug is hit:
+
+   echo '__schedule_bug:traceoff' > set_ftrace_filter
+
   These commands are cumulative whether or not they are appended
   to set_ftrace_filter. To remove a command, prepend it by '!'
   and drop the parameter:
 
+   echo '!__schedule_bug:traceoff:0' > set_ftrace_filter
+
+    The above removes the traceoff command for __schedule_bug
+    that have a counter. To remove commands without counters:
+
    echo '!__schedule_bug:traceoff' > set_ftrace_filter
 
+- snapshot
+  Will cause a snapshot to be triggered when the function is hit.
+
+   echo 'native_flush_tlb_others:snapshot' > set_ftrace_filter
+
+  To only snapshot once:
+
+   echo 'native_flush_tlb_others:snapshot:1' > set_ftrace_filter
+
+  To remove the above commands:
+
+   echo '!native_flush_tlb_others:snapshot' > set_ftrace_filter
+   echo '!native_flush_tlb_others:snapshot:0' > set_ftrace_filter
+
+- enable_event/disable_event
+  These commands can enable or disable a trace event. Note, because
+  function tracing callbacks are very sensitive, when these commands
+  are registered, the trace point is activated, but disabled in
+  a "soft" mode. That is, the tracepoint will be called, but
+  just will not be traced. The event tracepoint stays in this mode
+  as long as there's a command that triggers it.
+
+   echo 'try_to_wake_up:enable_event:sched:sched_switch:2' > \
+   	 set_ftrace_filter
+
+  The format is:
+
+    <function>:enable_event:<system>:<event>[:count]
+    <function>:disable_event:<system>:<event>[:count]
+
+  To remove the events commands:
+
+
+   echo '!try_to_wake_up:enable_event:sched:sched_switch:0' > \
+   	 set_ftrace_filter
+   echo '!schedule:disable_event:sched:sched_switch' > \
+   	 set_ftrace_filter
 
 trace_pipe
 ----------
···
  # cat trace
 # tracer: function
 #
-#           TASK-PID   CPU#    TIMESTAMP  FUNCTION
-#              | |      |          |         |
+# entries-in-buffer/entries-written: 0/0   #P:4
+#
+#                              _-----=> irqs-off
+#                             / _----=> need-resched
+#                            | / _---=> hardirq/softirq
+#                            || / _--=> preempt-depth
+#                            ||| /     delay
+#           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
+#              | |       |   ||||       |         |
 
  #
  # cat /tmp/trace.out
-            bash-4043  [00] 41.267106: finish_task_switch <-schedule
-            bash-4043  [00] 41.267106: hrtick_set <-schedule
-            bash-4043  [00] 41.267107: hrtick_clear <-hrtick_set
-            bash-4043  [00] 41.267108: wait_for_completion <-__stop_machine_run
-            bash-4043  [00] 41.267108: wait_for_common <-wait_for_completion
-            bash-4043  [00] 41.267109: kthread_stop <-stop_machine_run
-            bash-4043  [00] 41.267109: init_waitqueue_head <-kthread_stop
-            bash-4043  [00] 41.267110: wake_up_process <-kthread_stop
-            bash-4043  [00] 41.267110: try_to_wake_up <-wake_up_process
-            bash-4043  [00] 41.267111: select_task_rq_rt <-try_to_wake_up
+            bash-1994  [000] ....  5281.568961: mutex_unlock <-rb_simple_write
+            bash-1994  [000] ....  5281.568963: __mutex_unlock_slowpath <-mutex_unlock
+            bash-1994  [000] ....  5281.568963: __fsnotify_parent <-fsnotify_modify
+            bash-1994  [000] ....  5281.568964: fsnotify <-fsnotify_modify
+            bash-1994  [000] ....  5281.568964: __srcu_read_lock <-fsnotify
+            bash-1994  [000] ....  5281.568964: add_preempt_count <-__srcu_read_lock
+            bash-1994  [000] ...1  5281.568965: sub_preempt_count <-__srcu_read_lock
+            bash-1994  [000] ....  5281.568965: __srcu_read_unlock <-fsnotify
+            bash-1994  [000] ....  5281.568967: sys_dup2 <-system_call_fastpath
 
 
 Note, reading the trace_pipe file will block until more input is
-added. By changing the tracer, trace_pipe will issue an EOF. We
-needed to set the function tracer _before_ we "cat" the
-trace_pipe file.
-
+added.
 
 trace entries
 -------------
···
 diagnosing an issue in the kernel. The file buffer_size_kb is
 used to modify the size of the internal trace buffers. The
 number listed is the number of entries that can be recorded per
-CPU. To know the full size, multiply the number of possible CPUS
+CPU. To know the full size, multiply the number of possible CPUs
 with the number of entries.
 
  # cat buffer_size_kb
 1408 (units kilobytes)
 
-Note, to modify this, you must have tracing completely disabled.
-To do that, echo "nop" into the current_tracer. If the
-current_tracer is not set to "nop", an EINVAL error will be
-returned.
+Or simply read buffer_total_size_kb
 
- # echo nop > current_tracer
+ # cat buffer_total_size_kb 
+5632
+
+To modify the buffer, simple echo in a number (in 1024 byte segments).
+
  # echo 10000 > buffer_size_kb
  # cat buffer_size_kb
 10000 (units kilobytes)
 
-The number of pages which will be allocated is limited to a
-percentage of available memory. Allocating too much will produce
-an error.
+It will try to allocate as much as possible. If you allocate too
+much, it can cause Out-Of-Memory to trigger.
 
  # echo 1000000000000 > buffer_size_kb
 -bash: echo: write error: Cannot allocate memory
  # cat buffer_size_kb
 85
+
+The per_cpu buffers can be changed individually as well:
+
+ # echo 10000 > per_cpu/cpu0/buffer_size_kb
+ # echo 100 > per_cpu/cpu1/buffer_size_kb
+
+When the per_cpu buffers are not the same, the buffer_size_kb
+at the top level will just show an X
+
+ # cat buffer_size_kb
+X
+
+This is where the buffer_total_size_kb is useful:
+
+ # cat buffer_total_size_kb 
+12916
+
+Writing to the top level buffer_size_kb will reset all the buffers
+to be the same again.
 
 Snapshot
 --------
···
  # cat snapshot
 cat: snapshot: Device or resource busy
 
+
+Instances
+---------
+In the debugfs tracing directory is a directory called "instances".
+This directory can have new directories created inside of it using
+mkdir, and removing directories with rmdir. The directory created
+with mkdir in this directory will already contain files and other
+directories after it is created.
+
+ # mkdir instances/foo
+ # ls instances/foo
+buffer_size_kb  buffer_total_size_kb  events  free_buffer  per_cpu
+set_event  snapshot  trace  trace_clock  trace_marker  trace_options
+trace_pipe  tracing_on
+
+As you can see, the new directory looks similar to the tracing directory
+itself. In fact, it is very similar, except that the buffer and
+events are agnostic from the main director, or from any other
+instances that are created.
+
+The files in the new directory work just like the files with the
+same name in the tracing directory except the buffer that is used
+is a separate and new buffer. The files affect that buffer but do not
+affect the main buffer with the exception of trace_options. Currently,
+the trace_options affect all instances and the top level buffer
+the same, but this may change in future releases. That is, options
+may become specific to the instance they reside in.
+
+Notice that none of the function tracer files are there, nor is
+current_tracer and available_tracers. This is because the buffers
+can currently only have events enabled for them.
+
+ # mkdir instances/foo
+ # mkdir instances/bar
+ # mkdir instances/zoot
+ # echo 100000 > buffer_size_kb
+ # echo 1000 > instances/foo/buffer_size_kb
+ # echo 5000 > instances/bar/per_cpu/cpu1/buffer_size_kb
+ # echo function > current_trace
+ # echo 1 > instances/foo/events/sched/sched_wakeup/enable
+ # echo 1 > instances/foo/events/sched/sched_wakeup_new/enable
+ # echo 1 > instances/foo/events/sched/sched_switch/enable
+ # echo 1 > instances/bar/events/irq/enable
+ # echo 1 > instances/zoot/events/syscalls/enable
+ # cat trace_pipe
+CPU:2 [LOST 11745 EVENTS]
+            bash-2044  [002] .... 10594.481032: _raw_spin_lock_irqsave <-get_page_from_freelist
+            bash-2044  [002] d... 10594.481032: add_preempt_count <-_raw_spin_lock_irqsave
+            bash-2044  [002] d..1 10594.481032: __rmqueue <-get_page_from_freelist
+            bash-2044  [002] d..1 10594.481033: _raw_spin_unlock <-get_page_from_freelist
+            bash-2044  [002] d..1 10594.481033: sub_preempt_count <-_raw_spin_unlock
+            bash-2044  [002] d... 10594.481033: get_pageblock_flags_group <-get_pageblock_migratetype
+            bash-2044  [002] d... 10594.481034: __mod_zone_page_state <-get_page_from_freelist
+            bash-2044  [002] d... 10594.481034: zone_statistics <-get_page_from_freelist
+            bash-2044  [002] d... 10594.481034: __inc_zone_state <-zone_statistics
+            bash-2044  [002] d... 10594.481034: __inc_zone_state <-zone_statistics
+            bash-2044  [002] .... 10594.481035: arch_dup_task_struct <-copy_process
+[...]
+
+ # cat instances/foo/trace_pipe
+            bash-1998  [000] d..4   136.676759: sched_wakeup: comm=kworker/0:1 pid=59 prio=120 success=1 target_cpu=000
+            bash-1998  [000] dN.4   136.676760: sched_wakeup: comm=bash pid=1998 prio=120 success=1 target_cpu=000
+          <idle>-0     [003] d.h3   136.676906: sched_wakeup: comm=rcu_preempt pid=9 prio=120 success=1 target_cpu=003
+          <idle>-0     [003] d..3   136.676909: sched_switch: prev_comm=swapper/3 prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=rcu_preempt next_pid=9 next_prio=120
+     rcu_preempt-9     [003] d..3   136.676916: sched_switch: prev_comm=rcu_preempt prev_pid=9 prev_prio=120 prev_state=S ==> next_comm=swapper/3 next_pid=0 next_prio=120
+            bash-1998  [000] d..4   136.677014: sched_wakeup: comm=kworker/0:1 pid=59 prio=120 success=1 target_cpu=000
+            bash-1998  [000] dN.4   136.677016: sched_wakeup: comm=bash pid=1998 prio=120 success=1 target_cpu=000
+            bash-1998  [000] d..3   136.677018: sched_switch: prev_comm=bash prev_pid=1998 prev_prio=120 prev_state=R+ ==> next_comm=kworker/0:1 next_pid=59 next_prio=120
+     kworker/0:1-59    [000] d..4   136.677022: sched_wakeup: comm=sshd pid=1995 prio=120 success=1 target_cpu=001
+     kworker/0:1-59    [000] d..3   136.677025: sched_switch: prev_comm=kworker/0:1 prev_pid=59 prev_prio=120 prev_state=S ==> next_comm=bash next_pid=1998 next_prio=120
+[...]
+
+ # cat instances/bar/trace_pipe
+     migration/1-14    [001] d.h3   138.732674: softirq_raise: vec=3 [action=NET_RX]
+          <idle>-0     [001] dNh3   138.732725: softirq_raise: vec=3 [action=NET_RX]
+            bash-1998  [000] d.h1   138.733101: softirq_raise: vec=1 [action=TIMER]
+            bash-1998  [000] d.h1   138.733102: softirq_raise: vec=9 [action=RCU]
+            bash-1998  [000] ..s2   138.733105: softirq_entry: vec=1 [action=TIMER]
+            bash-1998  [000] ..s2   138.733106: softirq_exit: vec=1 [action=TIMER]
+            bash-1998  [000] ..s2   138.733106: softirq_entry: vec=9 [action=RCU]
+            bash-1998  [000] ..s2   138.733109: softirq_exit: vec=9 [action=RCU]
+            sshd-1995  [001] d.h1   138.733278: irq_handler_entry: irq=21 name=uhci_hcd:usb4
+            sshd-1995  [001] d.h1   138.733280: irq_handler_exit: irq=21 ret=unhandled
+            sshd-1995  [001] d.h1   138.733281: irq_handler_entry: irq=21 name=eth0
+            sshd-1995  [001] d.h1   138.733283: irq_handler_exit: irq=21 ret=handled
+[...]
+
+ # cat instances/zoot/trace
+# tracer: nop
+#
+# entries-in-buffer/entries-written: 18996/18996   #P:4
+#
+#                              _-----=> irqs-off
+#                             / _----=> need-resched
+#                            | / _---=> hardirq/softirq
+#                            || / _--=> preempt-depth
+#                            ||| /     delay
+#           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
+#              | |       |   ||||       |         |
+            bash-1998  [000] d...   140.733501: sys_write -> 0x2
+            bash-1998  [000] d...   140.733504: sys_dup2(oldfd: a, newfd: 1)
+            bash-1998  [000] d...   140.733506: sys_dup2 -> 0x1
+            bash-1998  [000] d...   140.733508: sys_fcntl(fd: a, cmd: 1, arg: 0)
+            bash-1998  [000] d...   140.733509: sys_fcntl -> 0x1
+            bash-1998  [000] d...   140.733510: sys_close(fd: a)
+            bash-1998  [000] d...   140.733510: sys_close -> 0x0
+            bash-1998  [000] d...   140.733514: sys_rt_sigprocmask(how: 0, nset: 0, oset: 6e2768, sigsetsize: 8)
+            bash-1998  [000] d...   140.733515: sys_rt_sigprocmask -> 0x0
+            bash-1998  [000] d...   140.733516: sys_rt_sigaction(sig: 2, act: 7fff718846f0, oact: 7fff71884650, sigsetsize: 8)
+            bash-1998  [000] d...   140.733516: sys_rt_sigaction -> 0x0
+
+You can see that the trace of the top most trace buffer shows only
+the function tracing. The foo instance displays wakeups and task
+switches.
+
+To remove the instances, simply delete their directories:
+
+ # rmdir instances/foo
+ # rmdir instances/bar
+ # rmdir instances/zoot
+
+Note, if a process has a trace file open in one of the instance
+directories, the rmdir will fail with EBUSY.
+
+
+Stack trace
 -----------
+Since the kernel has a fixed sized stack, it is important not to
+waste it in functions. A kernel developer must be conscience of
+what they allocate on the stack. If they add too much, the system
+can be in danger of a stack overflow, and corruption will occur,
+usually leading to a system panic.
+
+There are some tools that check this, usually with interrupts
+periodically checking usage. But if you can perform a check
+at every function call that will become very useful. As ftrace provides
+a function tracer, it makes it convenient to check the stack size
+at every function call. This is enabled via the stack tracer.
+
+CONFIG_STACK_TRACER enables the ftrace stack tracing functionality.
+To enable it, write a '1' into /proc/sys/kernel/stack_tracer_enabled.
+
+ # echo 1 > /proc/sys/kernel/stack_tracer_enabled
+
+You can also enable it from the kernel command line to trace
+the stack size of the kernel during boot up, by adding "stacktrace"
+to the kernel command line parameter.
+
+After running it for a few minutes, the output looks like:
+
+ # cat stack_max_size
+2928
+
+ # cat stack_trace
+        Depth    Size   Location    (18 entries)
+        -----    ----   --------
+  0)     2928     224   update_sd_lb_stats+0xbc/0x4ac
+  1)     2704     160   find_busiest_group+0x31/0x1f1
+  2)     2544     256   load_balance+0xd9/0x662
+  3)     2288      80   idle_balance+0xbb/0x130
+  4)     2208     128   __schedule+0x26e/0x5b9
+  5)     2080      16   schedule+0x64/0x66
+  6)     2064     128   schedule_timeout+0x34/0xe0
+  7)     1936     112   wait_for_common+0x97/0xf1
+  8)     1824      16   wait_for_completion+0x1d/0x1f
+  9)     1808     128   flush_work+0xfe/0x119
+ 10)     1680      16   tty_flush_to_ldisc+0x1e/0x20
+ 11)     1664      48   input_available_p+0x1d/0x5c
+ 12)     1616      48   n_tty_poll+0x6d/0x134
+ 13)     1568      64   tty_poll+0x64/0x7f
+ 14)     1504     880   do_select+0x31e/0x511
+ 15)      624     400   core_sys_select+0x177/0x216
+ 16)      224      96   sys_select+0x91/0xb9
+ 17)      128     128   system_call_fastpath+0x16/0x1b
+
+Note, if -mfentry is being used by gcc, functions get traced before
+they set up the stack frame. This means that leaf level functions
+are not tested by the stack tracer when -mfentry is used.
+
+Currently, -mfentry is used by gcc 4.6.0 and above on x86 only.
+
+---------
 
 More details can be found in the source code, in the
 kernel/trace/*.c files.

include/linux/ftrace.h

···
 	void			(*func)(unsigned long ip,
 					unsigned long parent_ip,
 					void **data);
-	int			(*callback)(unsigned long ip, void **data);
-	void			(*free)(void **data);
+	int			(*init)(struct ftrace_probe_ops *ops,
+					unsigned long ip, void **data);
+	void			(*free)(struct ftrace_probe_ops *ops,
+					unsigned long ip, void **data);
 	int			(*print)(struct seq_file *m,
 					 unsigned long ip,
 					 struct ftrace_probe_ops *ops,

include/linux/ftrace_event.h

···
 #include <linux/perf_event.h>
 
 struct trace_array;
+struct trace_buffer;
 struct tracer;
 struct dentry;
 
···
 const char *ftrace_print_hex_seq(struct trace_seq *p,
 				 const unsigned char *buf, int len);
 
+struct trace_iterator;
+struct trace_event;
+
+int ftrace_raw_output_prep(struct trace_iterator *iter,
+			   struct trace_event *event);
+
 /*
  * The trace entry - the most basic unit of tracing. This is what
  * is printed in the end as a single line in the trace output, such as:
···
 struct trace_iterator {
 	struct trace_array	*tr;
 	struct tracer		*trace;
+	struct trace_buffer	*trace_buffer;
 	void			*private;
 	int			cpu_file;
 	struct mutex		mutex;
···
 };
 
 
-struct trace_event;
-
 typedef enum print_line_t (*trace_print_func)(struct trace_iterator *iter,
 				      int flags, struct trace_event *event);
 
···
 void tracing_generic_entry_update(struct trace_entry *entry,
 				  unsigned long flags,
 				  int pc);
+struct ftrace_event_file;
+
+struct ring_buffer_event *
+trace_event_buffer_lock_reserve(struct ring_buffer **current_buffer,
+				struct ftrace_event_file *ftrace_file,
+				int type, unsigned long len,
+				unsigned long flags, int pc);
 struct ring_buffer_event *
 trace_current_buffer_lock_reserve(struct ring_buffer **current_buffer,
 				  int type, unsigned long len,
···
 			    enum trace_reg type, void *data);
 
 enum {
-	TRACE_EVENT_FL_ENABLED_BIT,
 	TRACE_EVENT_FL_FILTERED_BIT,
-	TRACE_EVENT_FL_RECORDED_CMD_BIT,
 	TRACE_EVENT_FL_CAP_ANY_BIT,
 	TRACE_EVENT_FL_NO_SET_FILTER_BIT,
 	TRACE_EVENT_FL_IGNORE_ENABLE_BIT,
+	TRACE_EVENT_FL_WAS_ENABLED_BIT,
 };
 
+/*
+ * Event flags:
+ *  FILTERED	  - The event has a filter attached
+ *  CAP_ANY	  - Any user can enable for perf
+ *  NO_SET_FILTER - Set when filter has error and is to be ignored
+ *  IGNORE_ENABLE - For ftrace internal events, do not enable with debugfs file
+ *  WAS_ENABLED   - Set and stays set when an event was ever enabled
+ *                    (used for module unloading, if a module event is enabled,
+ *                     it is best to clear the buffers that used it).
+ */
 enum {
-	TRACE_EVENT_FL_ENABLED		= (1 << TRACE_EVENT_FL_ENABLED_BIT),
 	TRACE_EVENT_FL_FILTERED		= (1 << TRACE_EVENT_FL_FILTERED_BIT),
-	TRACE_EVENT_FL_RECORDED_CMD	= (1 << TRACE_EVENT_FL_RECORDED_CMD_BIT),
 	TRACE_EVENT_FL_CAP_ANY		= (1 << TRACE_EVENT_FL_CAP_ANY_BIT),
 	TRACE_EVENT_FL_NO_SET_FILTER	= (1 << TRACE_EVENT_FL_NO_SET_FILTER_BIT),
 	TRACE_EVENT_FL_IGNORE_ENABLE	= (1 << TRACE_EVENT_FL_IGNORE_ENABLE_BIT),
+	TRACE_EVENT_FL_WAS_ENABLED	= (1 << TRACE_EVENT_FL_WAS_ENABLED_BIT),
 };
 
 struct ftrace_event_call {
 	struct list_head	list;
 	struct ftrace_event_class *class;
 	char			*name;
-	struct dentry		*dir;
 	struct trace_event	event;
 	const char		*print_fmt;
 	struct event_filter	*filter;
+	struct list_head	*files;
 	void			*mod;
 	void			*data;
-
 	/*
-	 * 32 bit flags:
-	 *   bit 1:		enabled
-	 *   bit 2:		filter_active
-	 *   bit 3:		enabled cmd record
-	 *   bit 4:		allow trace by non root (cap any)
-	 *   bit 5:		failed to apply filter
-	 *   bit 6:		ftrace internal event (do not enable)
-	 *
-	 * Changes to flags must hold the event_mutex.
-	 *
-	 * Note: Reads of flags do not hold the event_mutex since
-	 * they occur in critical sections. But the way flags
-	 * is currently used, these changes do no affect the code
-	 * except that when a change is made, it may have a slight
-	 * delay in propagating the changes to other CPUs due to
-	 * caching and such.
+	 *   bit 0:		filter_active
+	 *   bit 1:		allow trace by non root (cap any)
+	 *   bit 2:		failed to apply filter
+	 *   bit 3:		ftrace internal event (do not enable)
+	 *   bit 4:		Event was enabled by module
 	 */
-	unsigned int		flags;
+	int			flags; /* static flags of different events */
 
 #ifdef CONFIG_PERF_EVENTS
 	int				perf_refcount;
 	struct hlist_head __percpu	*perf_events;
 #endif
+};
+
+struct trace_array;
+struct ftrace_subsystem_dir;
+
+enum {
+	FTRACE_EVENT_FL_ENABLED_BIT,
+	FTRACE_EVENT_FL_RECORDED_CMD_BIT,
+	FTRACE_EVENT_FL_SOFT_MODE_BIT,
+	FTRACE_EVENT_FL_SOFT_DISABLED_BIT,
+};
+
+/*
+ * Ftrace event file flags:
+ *  ENABLED	  - The event is enabled
+ *  RECORDED_CMD  - The comms should be recorded at sched_switch
+ *  SOFT_MODE     - The event is enabled/disabled by SOFT_DISABLED
+ *  SOFT_DISABLED - When set, do not trace the event (even though its
+ *                   tracepoint may be enabled)
+ */
+enum {
+	FTRACE_EVENT_FL_ENABLED		= (1 << FTRACE_EVENT_FL_ENABLED_BIT),
+	FTRACE_EVENT_FL_RECORDED_CMD	= (1 << FTRACE_EVENT_FL_RECORDED_CMD_BIT),
+	FTRACE_EVENT_FL_SOFT_MODE	= (1 << FTRACE_EVENT_FL_SOFT_MODE_BIT),
+	FTRACE_EVENT_FL_SOFT_DISABLED	= (1 << FTRACE_EVENT_FL_SOFT_DISABLED_BIT),
+};
+
+struct ftrace_event_file {
+	struct list_head		list;
+	struct ftrace_event_call	*event_call;
+	struct dentry			*dir;
+	struct trace_array		*tr;
+	struct ftrace_subsystem_dir	*system;
+
+	/*
+	 * 32 bit flags:
+	 *   bit 0:		enabled
+	 *   bit 1:		enabled cmd record
+	 *   bit 2:		enable/disable with the soft disable bit
+	 *   bit 3:		soft disabled
+	 *
+	 * Note: The bits must be set atomically to prevent races
+	 * from other writers. Reads of flags do not need to be in
+	 * sync as they occur in critical sections. But the way flags
+	 * is currently used, these changes do not affect the code
+	 * except that when a change is made, it may have a slight
+	 * delay in propagating the changes to other CPUs due to
+	 * caching and such. Which is mostly OK ;-)
+	 */
+	unsigned long		flags;
 };
 
 #define __TRACE_EVENT_FLAGS(name, value)				\
···
 extern int trace_add_event_call(struct ftrace_event_call *call);
 extern void trace_remove_event_call(struct ftrace_event_call *call);
 
-#define is_signed_type(type)	(((type)(-1)) < (type)0)
+#define is_signed_type(type)	(((type)(-1)) < (type)1)
 
 int trace_set_clr_event(const char *system, const char *event, int set);
 

include/linux/kernel.h

···
 void tracing_on(void);
 void tracing_off(void);
 int tracing_is_on(void);
+void tracing_snapshot(void);
+void tracing_snapshot_alloc(void);
 
 extern void tracing_start(void);
 extern void tracing_stop(void);
···
  *
  * This is intended as a debugging tool for the developer only.
  * Please refrain from leaving trace_printks scattered around in
- * your code.
+ * your code. (Extra memory is used for special buffers that are
+ * allocated when trace_printk() is used)
+ *
+ * A little optization trick is done here. If there's only one
+ * argument, there's no need to scan the string for printf formats.
+ * The trace_puts() will suffice. But how can we take advantage of
+ * using trace_puts() when trace_printk() has only one argument?
+ * By stringifying the args and checking the size we can tell
+ * whether or not there are args. __stringify((__VA_ARGS__)) will
+ * turn into "()\0" with a size of 3 when there are no args, anything
+ * else will be bigger. All we need to do is define a string to this,
+ * and then take its size and compare to 3. If it's bigger, use
+ * do_trace_printk() otherwise, optimize it to trace_puts(). Then just
+ * let gcc optimize the rest.
  */
 
-#define trace_printk(fmt, args...)					\
+#define trace_printk(fmt, ...)				\
+do {							\
+	char _______STR[] = __stringify((__VA_ARGS__));	\
+	if (sizeof(_______STR) > 3)			\
+		do_trace_printk(fmt, ##__VA_ARGS__);	\
+	else						\
+		trace_puts(fmt);			\
+} while (0)
+
+#define do_trace_printk(fmt, args...)					\
 do {									\
 	static const char *trace_printk_fmt				\
 		__attribute__((section("__trace_printk_fmt"))) =	\
···
 extern __printf(2, 3)
 int __trace_printk(unsigned long ip, const char *fmt, ...);
 
-extern void trace_dump_stack(void);
+/**
+ * trace_puts - write a string into the ftrace buffer
+ * @str: the string to record
+ *
+ * Note: __trace_bputs is an internal function for trace_puts and
+ *       the @ip is passed in via the trace_puts macro.
+ *
+ * This is similar to trace_printk() but is made for those really fast
+ * paths that a developer wants the least amount of "Heisenbug" affects,
+ * where the processing of the print format is still too much.
+ *
+ * This function allows a kernel developer to debug fast path sections
+ * that printk is not appropriate for. By scattering in various
+ * printk like tracing in the code, a developer can quickly see
+ * where problems are occurring.
+ *
+ * This is intended as a debugging tool for the developer only.
+ * Please refrain from leaving trace_puts scattered around in
+ * your code. (Extra memory is used for special buffers that are
+ * allocated when trace_puts() is used)
+ *
+ * Returns: 0 if nothing was written, positive # if string was.
+ *  (1 when __trace_bputs is used, strlen(str) when __trace_puts is used)
+ */
+
+extern int __trace_bputs(unsigned long ip, const char *str);
+extern int __trace_puts(unsigned long ip, const char *str, int size);
+#define trace_puts(str) ({						\
+	static const char *trace_printk_fmt				\
+		__attribute__((section("__trace_printk_fmt"))) =	\
+		__builtin_constant_p(str) ? str : NULL;			\
+									\
+	if (__builtin_constant_p(str))					\
+		__trace_bputs(_THIS_IP_, trace_printk_fmt);		\
+	else								\
+		__trace_puts(_THIS_IP_, str, strlen(str));		\
+})
+
+extern void trace_dump_stack(int skip);
 
 /*
  * The double __builtin_constant_p is because gcc will give us an error
···
 static inline void tracing_on(void) { }
 static inline void tracing_off(void) { }
 static inline int tracing_is_on(void) { return 0; }
+static inline void tracing_snapshot(void) { }
+static inline void tracing_snapshot_alloc(void) { }
 
 static inline __printf(1, 2)
 int trace_printk(const char *fmt, ...)

include/linux/ring_buffer.h

···
 #include <linux/kmemcheck.h>
 #include <linux/mm.h>
 #include <linux/seq_file.h>
+#include <linux/poll.h>
 
 struct ring_buffer;
 struct ring_buffer_iter;
···
 	static struct lock_class_key __key;		\
 	__ring_buffer_alloc((size), (flags), &__key);	\
 })
+
+void ring_buffer_wait(struct ring_buffer *buffer, int cpu);
+int ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu,
+			  struct file *filp, poll_table *poll_table);
+
 
 #define RING_BUFFER_ALL_CPUS -1
 

include/linux/trace_clock.h

···
 
 extern u64 notrace trace_clock_local(void);
 extern u64 notrace trace_clock(void);
+extern u64 notrace trace_clock_jiffies(void);
 extern u64 notrace trace_clock_global(void);
 extern u64 notrace trace_clock_counter(void);
 

include/trace/ftrace.h

···
 ftrace_raw_output_##call(struct trace_iterator *iter, int flags,	\
 			 struct trace_event *trace_event)		\
 {									\
-	struct ftrace_event_call *event;				\
 	struct trace_seq *s = &iter->seq;				\
+	struct trace_seq __maybe_unused *p = &iter->tmp_seq;		\
 	struct ftrace_raw_##call *field;				\
-	struct trace_entry *entry;					\
-	struct trace_seq *p = &iter->tmp_seq;				\
 	int ret;							\
 									\
-	event = container_of(trace_event, struct ftrace_event_call,	\
-			     event);					\
+	field = (typeof(field))iter->ent;				\
 									\
-	entry = iter->ent;						\
-									\
-	if (entry->type != event->event.type) {				\
-		WARN_ON_ONCE(1);					\
-		return TRACE_TYPE_UNHANDLED;				\
-	}								\
-									\
-	field = (typeof(field))entry;					\
-									\
-	trace_seq_init(p);						\
-	ret = trace_seq_printf(s, "%s: ", event->name);			\
+	ret = ftrace_raw_output_prep(iter, trace_event);		\
 	if (ret)							\
-		ret = trace_seq_printf(s, print);			\
+		return ret;						\
+									\
+	ret = trace_seq_printf(s, print);				\
 	if (!ret)							\
 		return TRACE_TYPE_PARTIAL_LINE;				\
 									\
···
 
 #undef DECLARE_EVENT_CLASS
 #define DECLARE_EVENT_CLASS(call, proto, args, tstruct, func, print)	\
-static int notrace							\
+static int notrace __init						\
 ftrace_define_fields_##call(struct ftrace_event_call *event_call)	\
 {									\
 	struct ftrace_raw_##call field;					\
···
  *
  * static void ftrace_raw_event_<call>(void *__data, proto)
  * {
- *	struct ftrace_event_call *event_call = __data;
+ *	struct ftrace_event_file *ftrace_file = __data;
+ *	struct ftrace_event_call *event_call = ftrace_file->event_call;
  *	struct ftrace_data_offsets_<call> __maybe_unused __data_offsets;
  *	struct ring_buffer_event *event;
  *	struct ftrace_raw_<call> *entry; <-- defined in stage 1
···
  *	int __data_size;
  *	int pc;
  *
+ *	if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT,
+ *		     &ftrace_file->flags))
+ *		return;
+ *
  *	local_save_flags(irq_flags);
  *	pc = preempt_count();
  *
  *	__data_size = ftrace_get_offsets_<call>(&__data_offsets, args);
  *
- *	event = trace_current_buffer_lock_reserve(&buffer,
+ *	event = trace_event_buffer_lock_reserve(&buffer, ftrace_file,
  *				  event_<call>->event.type,
  *				  sizeof(*entry) + __data_size,
  *				  irq_flags, pc);
···
  *			   __array macros.
  *
  *	if (!filter_current_check_discard(buffer, event_call, entry, event))
- *		trace_current_buffer_unlock_commit(buffer,
+ *		trace_nowake_buffer_unlock_commit(buffer,
  *						   event, irq_flags, pc);
  * }
  *
···
 static notrace void							\
 ftrace_raw_event_##call(void *__data, proto)				\
 {									\
-	struct ftrace_event_call *event_call = __data;			\
+	struct ftrace_event_file *ftrace_file = __data;			\
+	struct ftrace_event_call *event_call = ftrace_file->event_call;	\
 	struct ftrace_data_offsets_##call __maybe_unused __data_offsets;\
 	struct ring_buffer_event *event;				\
 	struct ftrace_raw_##call *entry;				\
···
 	int __data_size;						\
 	int pc;								\
 									\
+	if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT,			\
+		     &ftrace_file->flags))				\
+		return;							\
+									\
 	local_save_flags(irq_flags);					\
 	pc = preempt_count();						\
 									\
 	__data_size = ftrace_get_offsets_##call(&__data_offsets, args); \
 									\
-	event = trace_current_buffer_lock_reserve(&buffer,		\
+	event = trace_event_buffer_lock_reserve(&buffer, ftrace_file,	\
 				 event_call->event.type,		\
 				 sizeof(*entry) + __data_size,		\
 				 irq_flags, pc);			\
···
 #define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print)	\
 _TRACE_PERF_PROTO(call, PARAMS(proto));					\
 static const char print_fmt_##call[] = print;				\
-static struct ftrace_event_class __used event_class_##call = {		\
+static struct ftrace_event_class __used __refdata event_class_##call = { \
 	.system			= __stringify(TRACE_SYSTEM),		\
 	.define_fields		= ftrace_define_fields_##call,		\
 	.fields			= LIST_HEAD_INIT(event_class_##call.fields),\
···
 
 #include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
 #endif /* CONFIG_PERF_EVENTS */
-
-#undef _TRACE_PROFILE_INIT
 

kernel/trace/Kconfig

···
 	select GENERIC_TRACER
 	select TRACER_MAX_TRACE
 	select RING_BUFFER_ALLOW_SWAP
+	select TRACER_SNAPSHOT
+	select TRACER_SNAPSHOT_PER_CPU_SWAP
 	help
 	  This option measures the time spent in irqs-off critical
 	  sections, with microsecond accuracy.
···
 	select GENERIC_TRACER
 	select TRACER_MAX_TRACE
 	select RING_BUFFER_ALLOW_SWAP
+	select TRACER_SNAPSHOT
+	select TRACER_SNAPSHOT_PER_CPU_SWAP
 	help
 	  This option measures the time spent in preemption-off critical
 	  sections, with microsecond accuracy.
···
 	select GENERIC_TRACER
 	select CONTEXT_SWITCH_TRACER
 	select TRACER_MAX_TRACE
+	select TRACER_SNAPSHOT
 	help
 	  This tracer tracks the latency of the highest priority task
 	  to be scheduled in, starting from the point it has woken up.
···
 
 	      echo 1 > /sys/kernel/debug/tracing/snapshot
 	      cat snapshot
+
+config TRACER_SNAPSHOT_PER_CPU_SWAP
+        bool "Allow snapshot to swap per CPU"
+	depends on TRACER_SNAPSHOT
+	select RING_BUFFER_ALLOW_SWAP
+	help
+	  Allow doing a snapshot of a single CPU buffer instead of a
+	  full swap (all buffers). If this is set, then the following is
+	  allowed:
+
+	      echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot
+
+	  After which, only the tracing buffer for CPU 2 was swapped with
+	  the main tracing buffer, and the other CPU buffers remain the same.
+
+	  When this is enabled, this adds a little more overhead to the
+	  trace recording, as it needs to add some checks to synchronize
+	  recording with swaps. But this does not affect the performance
+	  of the overall system. This is enabled by default when the preempt
+	  or irq latency tracers are enabled, as those need to swap as well
+	  and already adds the overhead (plus a lot more).
 
 config TRACE_BRANCH_PROFILING
 	bool
···
 	  affected by processes that are running.
 
 	  If unsure, say N.
+
+config RING_BUFFER_STARTUP_TEST
+       bool "Ring buffer startup self test"
+       depends on RING_BUFFER
+       help
+         Run a simple self test on the ring buffer on boot up. Late in the
+	 kernel boot sequence, the test will start that kicks off
+	 a thread per cpu. Each thread will write various size events
+	 into the ring buffer. Another thread is created to send IPIs
+	 to each of the threads, where the IPI handler will also write
+	 to the ring buffer, to test/stress the nesting ability.
+	 If any anomalies are discovered, a warning will be displayed
+	 and all ring buffers will be disabled.
+
+	 The test runs for 10 seconds. This will slow your boot time
+	 by at least 10 more seconds.
+
+	 At the end of the test, statics and more checks are done.
+	 It will output the stats of each per cpu buffer. What
+	 was written, the sizes, what was read, what was lost, and
+	 other similar details.
+
+	 If unsure, say N
 
 endif # FTRACE
 

kernel/trace/blktrace.c

···
 	bool blk_tracer = blk_tracer_enabled;
 
 	if (blk_tracer) {
-		buffer = blk_tr->buffer;
+		buffer = blk_tr->trace_buffer.buffer;
 		pc = preempt_count();
 		event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
 						  sizeof(*t) + len,
···
 	if (blk_tracer) {
 		tracing_record_cmdline(current);
 
-		buffer = blk_tr->buffer;
+		buffer = blk_tr->trace_buffer.buffer;
 		pc = preempt_count();
 		event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
 						  sizeof(*t) + pdu_len,

kernel/trace/ftrace.c

···
 #define PROFILES_PER_PAGE					\
 	(PROFILE_RECORDS_SIZE / sizeof(struct ftrace_profile))
 
-static int ftrace_profile_bits __read_mostly;
 static int ftrace_profile_enabled __read_mostly;
 
 /* ftrace_profile_lock - synchronize the enable and disable of the profiler */
···
 
 static DEFINE_PER_CPU(struct ftrace_profile_stat, ftrace_profile_stats);
 
-#define FTRACE_PROFILE_HASH_SIZE 1024 /* must be power of 2 */
+#define FTRACE_PROFILE_HASH_BITS 10
+#define FTRACE_PROFILE_HASH_SIZE (1 << FTRACE_PROFILE_HASH_BITS)
 
 static void *
 function_stat_next(void *v, int idx)
···
 
 	pages = DIV_ROUND_UP(functions, PROFILES_PER_PAGE);
 
-	for (i = 0; i < pages; i++) {
+	for (i = 1; i < pages; i++) {
 		pg->next = (void *)get_zeroed_page(GFP_KERNEL);
 		if (!pg->next)
 			goto out_free;
···
 	if (!stat->hash)
 		return -ENOMEM;
 
-	if (!ftrace_profile_bits) {
-		size--;
-
-		for (; size; size >>= 1)
-			ftrace_profile_bits++;
-	}
-
 	/* Preallocate the function profiling pages */
 	if (ftrace_profile_pages_init(stat) < 0) {
 		kfree(stat->hash);
···
 	struct hlist_head *hhd;
 	unsigned long key;
 
-	key = hash_long(ip, ftrace_profile_bits);
+	key = hash_long(ip, FTRACE_PROFILE_HASH_BITS);
 	hhd = &stat->hash[key];
 
 	if (hlist_empty(hhd))
···
 {
 	unsigned long key;
 
-	key = hash_long(rec->ip, ftrace_profile_bits);
+	key = hash_long(rec->ip, FTRACE_PROFILE_HASH_BITS);
 	hlist_add_head_rcu(&rec->node, &stat->hash[key]);
 }
 
···
 	unsigned long		flags;
 	unsigned long		ip;
 	void			*data;
-	struct rcu_head		rcu;
+	struct list_head	free_list;
 };
 
 struct ftrace_func_entry {
···
 	struct hlist_head *hhd;
 	struct ftrace_hash *old_hash;
 	struct ftrace_hash *new_hash;
-	unsigned long key;
 	int size = src->count;
 	int bits = 0;
 	int ret;
···
 	for (i = 0; i < size; i++) {
 		hhd = &src->buckets[i];
 		hlist_for_each_entry_safe(entry, tn, hhd, hlist) {
-			if (bits > 0)
-				key = hash_long(entry->ip, bits);
-			else
-				key = 0;
 			remove_hash_entry(src, entry);
 			__add_hash_entry(new_hash, entry);
 		}
···
 }
 
 
-static void ftrace_free_entry_rcu(struct rcu_head *rhp)
+static void ftrace_free_entry(struct ftrace_func_probe *entry)
 {
-	struct ftrace_func_probe *entry =
-		container_of(rhp, struct ftrace_func_probe, rcu);
-
 	if (entry->ops->free)
-		entry->ops->free(&entry->data);
+		entry->ops->free(entry->ops, entry->ip, &entry->data);
 	kfree(entry);
 }
-
 
 int
 register_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops,
 			      void *data)
 {
 	struct ftrace_func_probe *entry;
+	struct ftrace_hash **orig_hash = &trace_probe_ops.filter_hash;
+	struct ftrace_hash *hash;
 	struct ftrace_page *pg;
 	struct dyn_ftrace *rec;
 	int type, len, not;
 	unsigned long key;
 	int count = 0;
 	char *search;
+	int ret;
 
 	type = filter_parse_regex(glob, strlen(glob), &search, &not);
 	len = strlen(search);
···
 
 	mutex_lock(&ftrace_lock);
 
-	if (unlikely(ftrace_disabled))
+	hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);
+	if (!hash) {
+		count = -ENOMEM;
 		goto out_unlock;
+	}
+
+	if (unlikely(ftrace_disabled)) {
+		count = -ENODEV;
+		goto out_unlock;
+	}
 
 	do_for_each_ftrace_rec(pg, rec) {
 
···
 		 * for each function we find. We call the callback
 		 * to give the caller an opportunity to do so.
 		 */
-		if (ops->callback) {
-			if (ops->callback(rec->ip, &entry->data) < 0) {
+		if (ops->init) {
+			if (ops->init(ops, rec->ip, &entry->data) < 0) {
 				/* caller does not like this func */
 				kfree(entry);
 				continue;
 			}
+		}
+
+		ret = enter_record(hash, rec, 0);
+		if (ret < 0) {
+			kfree(entry);
+			count = ret;
+			goto out_unlock;
 		}
 
 		entry->ops = ops;
···
 		hlist_add_head_rcu(&entry->node, &ftrace_func_hash[key]);
 
 	} while_for_each_ftrace_rec();
+
+	ret = ftrace_hash_move(&trace_probe_ops, 1, orig_hash, hash);
+	if (ret < 0)
+		count = ret;
+
 	__enable_ftrace_function_probe();
 
  out_unlock:
 	mutex_unlock(&ftrace_lock);
+	free_ftrace_hash(hash);
 
 	return count;
 }
···
 __unregister_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops,
 				  void *data, int flags)
 {
+	struct ftrace_func_entry *rec_entry;
 	struct ftrace_func_probe *entry;
+	struct ftrace_func_probe *p;
+	struct ftrace_hash **orig_hash = &trace_probe_ops.filter_hash;
+	struct list_head free_list;
+	struct ftrace_hash *hash;
 	struct hlist_node *tmp;
 	char str[KSYM_SYMBOL_LEN];
 	int type = MATCH_FULL;
···
 	}
 
 	mutex_lock(&ftrace_lock);
+
+	hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);
+	if (!hash)
+		/* Hmm, should report this somehow */
+		goto out_unlock;
+
+	INIT_LIST_HEAD(&free_list);
+
 	for (i = 0; i < FTRACE_FUNC_HASHSIZE; i++) {
 		struct hlist_head *hhd = &ftrace_func_hash[i];
 
···
 					continue;
 			}
 
+			rec_entry = ftrace_lookup_ip(hash, entry->ip);
+			/* It is possible more than one entry had this ip */
+			if (rec_entry)
+				free_hash_entry(hash, rec_entry);
+
 			hlist_del_rcu(&entry->node);
-			call_rcu_sched(&entry->rcu, ftrace_free_entry_rcu);
+			list_add(&entry->free_list, &free_list);
 		}
 	}
 	__disable_ftrace_function_probe();
+	/*
+	 * Remove after the disable is called. Otherwise, if the last
+	 * probe is removed, a null hash means *all enabled*.
+	 */
+	ftrace_hash_move(&trace_probe_ops, 1, orig_hash, hash);
+	synchronize_sched();
+	list_for_each_entry_safe(entry, p, &free_list, free_list) {
+		list_del(&entry->free_list);
+		ftrace_free_entry(entry);
+	}
+		
+ out_unlock:
 	mutex_unlock(&ftrace_lock);
+	free_ftrace_hash(hash);
 }
 
 void
···
 	if (fail)
 		return -EINVAL;
 
-	ftrace_graph_filter_enabled = 1;
+	ftrace_graph_filter_enabled = !!(*idx);
+
 	return 0;
 }
 

kernel/trace/ring_buffer.c

···
 #include <linux/trace_clock.h>
 #include <linux/trace_seq.h>
 #include <linux/spinlock.h>
+#include <linux/irq_work.h>
 #include <linux/debugfs.h>
 #include <linux/uaccess.h>
 #include <linux/hardirq.h>
+#include <linux/kthread.h>	/* for self test */
 #include <linux/kmemcheck.h>
 #include <linux/module.h>
 #include <linux/percpu.h>
 #include <linux/mutex.h>
+#include <linux/delay.h>
 #include <linux/slab.h>
 #include <linux/init.h>
 #include <linux/hash.h>
···
 	return ret;
 }
 
+struct rb_irq_work {
+	struct irq_work			work;
+	wait_queue_head_t		waiters;
+	bool				waiters_pending;
+};
+
 /*
  * head_page == tail_page && head == tail then buffer is empty.
  */
···
 	struct list_head		new_pages; /* new pages to add */
 	struct work_struct		update_pages_work;
 	struct completion		update_done;
+
+	struct rb_irq_work		irq_work;
 };
 
 struct ring_buffer {
···
 	struct notifier_block		cpu_notify;
 #endif
 	u64				(*clock)(void);
+
+	struct rb_irq_work		irq_work;
 };
 
 struct ring_buffer_iter {
···
 	unsigned long			cache_read;
 	u64				read_stamp;
 };
+
+/*
+ * rb_wake_up_waiters - wake up tasks waiting for ring buffer input
+ *
+ * Schedules a delayed work to wake up any task that is blocked on the
+ * ring buffer waiters queue.
+ */
+static void rb_wake_up_waiters(struct irq_work *work)
+{
+	struct rb_irq_work *rbwork = container_of(work, struct rb_irq_work, work);
+
+	wake_up_all(&rbwork->waiters);
+}
+
+/**
+ * ring_buffer_wait - wait for input to the ring buffer
+ * @buffer: buffer to wait on
+ * @cpu: the cpu buffer to wait on
+ *
+ * If @cpu == RING_BUFFER_ALL_CPUS then the task will wake up as soon
+ * as data is added to any of the @buffer's cpu buffers. Otherwise
+ * it will wait for data to be added to a specific cpu buffer.
+ */
+void ring_buffer_wait(struct ring_buffer *buffer, int cpu)
+{
+	struct ring_buffer_per_cpu *cpu_buffer;
+	DEFINE_WAIT(wait);
+	struct rb_irq_work *work;
+
+	/*
+	 * Depending on what the caller is waiting for, either any
+	 * data in any cpu buffer, or a specific buffer, put the
+	 * caller on the appropriate wait queue.
+	 */
+	if (cpu == RING_BUFFER_ALL_CPUS)
+		work = &buffer->irq_work;
+	else {
+		cpu_buffer = buffer->buffers[cpu];
+		work = &cpu_buffer->irq_work;
+	}
+
+
+	prepare_to_wait(&work->waiters, &wait, TASK_INTERRUPTIBLE);
+
+	/*
+	 * The events can happen in critical sections where
+	 * checking a work queue can cause deadlocks.
+	 * After adding a task to the queue, this flag is set
+	 * only to notify events to try to wake up the queue
+	 * using irq_work.
+	 *
+	 * We don't clear it even if the buffer is no longer
+	 * empty. The flag only causes the next event to run
+	 * irq_work to do the work queue wake up. The worse
+	 * that can happen if we race with !trace_empty() is that
+	 * an event will cause an irq_work to try to wake up
+	 * an empty queue.
+	 *
+	 * There's no reason to protect this flag either, as
+	 * the work queue and irq_work logic will do the necessary
+	 * synchronization for the wake ups. The only thing
+	 * that is necessary is that the wake up happens after
+	 * a task has been queued. It's OK for spurious wake ups.
+	 */
+	work->waiters_pending = true;
+
+	if ((cpu == RING_BUFFER_ALL_CPUS && ring_buffer_empty(buffer)) ||
+	    (cpu != RING_BUFFER_ALL_CPUS && ring_buffer_empty_cpu(buffer, cpu)))
+		schedule();
+
+	finish_wait(&work->waiters, &wait);
+}
+
+/**
+ * ring_buffer_poll_wait - poll on buffer input
+ * @buffer: buffer to wait on
+ * @cpu: the cpu buffer to wait on
+ * @filp: the file descriptor
+ * @poll_table: The poll descriptor
+ *
+ * If @cpu == RING_BUFFER_ALL_CPUS then the task will wake up as soon
+ * as data is added to any of the @buffer's cpu buffers. Otherwise
+ * it will wait for data to be added to a specific cpu buffer.
+ *
+ * Returns POLLIN | POLLRDNORM if data exists in the buffers,
+ * zero otherwise.
+ */
+int ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu,
+			  struct file *filp, poll_table *poll_table)
+{
+	struct ring_buffer_per_cpu *cpu_buffer;
+	struct rb_irq_work *work;
+
+	if ((cpu == RING_BUFFER_ALL_CPUS && !ring_buffer_empty(buffer)) ||
+	    (cpu != RING_BUFFER_ALL_CPUS && !ring_buffer_empty_cpu(buffer, cpu)))
+		return POLLIN | POLLRDNORM;
+
+	if (cpu == RING_BUFFER_ALL_CPUS)
+		work = &buffer->irq_work;
+	else {
+		cpu_buffer = buffer->buffers[cpu];
+		work = &cpu_buffer->irq_work;
+	}
+
+	work->waiters_pending = true;
+	poll_wait(filp, &work->waiters, poll_table);
+
+	if ((cpu == RING_BUFFER_ALL_CPUS && !ring_buffer_empty(buffer)) ||
+	    (cpu != RING_BUFFER_ALL_CPUS && !ring_buffer_empty_cpu(buffer, cpu)))
+		return POLLIN | POLLRDNORM;
+	return 0;
+}
 
 /* buffer may be either ring_buffer or ring_buffer_per_cpu */
 #define RB_WARN_ON(b, cond)						\
···
 	cpu_buffer->lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
 	INIT_WORK(&cpu_buffer->update_pages_work, update_pages_handler);
 	init_completion(&cpu_buffer->update_done);
+	init_irq_work(&cpu_buffer->irq_work.work, rb_wake_up_waiters);
+	init_waitqueue_head(&cpu_buffer->irq_work.waiters);
 
 	bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()),
 			    GFP_KERNEL, cpu_to_node(cpu));
···
 	buffer->flags = flags;
 	buffer->clock = trace_clock_local;
 	buffer->reader_lock_key = key;
+
+	init_irq_work(&buffer->irq_work.work, rb_wake_up_waiters);
+	init_waitqueue_head(&buffer->irq_work.waiters);
 
 	/* need at least two pages */
 	if (nr_pages < 2)
···
 			if (!cpu_buffer->nr_pages_to_update)
 				continue;
 
-			if (cpu_online(cpu))
+			/* The update must run on the CPU that is being updated. */
+			preempt_disable();
+			if (cpu == smp_processor_id() || !cpu_online(cpu)) {
+				rb_update_pages(cpu_buffer);
+				cpu_buffer->nr_pages_to_update = 0;
+			} else {
+				/*
+				 * Can not disable preemption for schedule_work_on()
+				 * on PREEMPT_RT.
+				 */
+				preempt_enable();
 				schedule_work_on(cpu,
 						&cpu_buffer->update_pages_work);
-			else
-				rb_update_pages(cpu_buffer);
+				preempt_disable();
+			}
+			preempt_enable();
 		}
 
 		/* wait for all the updates to complete */
···
 
 		get_online_cpus();
 
-		if (cpu_online(cpu_id)) {
+		preempt_disable();
+		/* The update must run on the CPU that is being updated. */
+		if (cpu_id == smp_processor_id() || !cpu_online(cpu_id))
+			rb_update_pages(cpu_buffer);
+		else {
+			/*
+			 * Can not disable preemption for schedule_work_on()
+			 * on PREEMPT_RT.
+			 */
+			preempt_enable();
 			schedule_work_on(cpu_id,
 					 &cpu_buffer->update_pages_work);
 			wait_for_completion(&cpu_buffer->update_done);
-		} else
-			rb_update_pages(cpu_buffer);
+			preempt_disable();
+		}
+		preempt_enable();
 
 		cpu_buffer->nr_pages_to_update = 0;
 		put_online_cpus();
···
 	rb_end_commit(cpu_buffer);
 }
 
+static __always_inline void
+rb_wakeups(struct ring_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer)
+{
+	if (buffer->irq_work.waiters_pending) {
+		buffer->irq_work.waiters_pending = false;
+		/* irq_work_queue() supplies it's own memory barriers */
+		irq_work_queue(&buffer->irq_work.work);
+	}
+
+	if (cpu_buffer->irq_work.waiters_pending) {
+		cpu_buffer->irq_work.waiters_pending = false;
+		/* irq_work_queue() supplies it's own memory barriers */
+		irq_work_queue(&cpu_buffer->irq_work.work);
+	}
+}
+
 /**
  * ring_buffer_unlock_commit - commit a reserved
  * @buffer: The buffer to commit to
···
 	cpu_buffer = buffer->buffers[cpu];
 
 	rb_commit(cpu_buffer, event);
+
+	rb_wakeups(buffer, cpu_buffer);
 
 	trace_recursive_unlock();
 
···
 	memcpy(body, data, length);
 
 	rb_commit(cpu_buffer, event);
+
+	rb_wakeups(buffer, cpu_buffer);
 
 	ret = 0;
  out:
···
 	return NOTIFY_OK;
 }
 #endif
+
+#ifdef CONFIG_RING_BUFFER_STARTUP_TEST
+/*
+ * This is a basic integrity check of the ring buffer.
+ * Late in the boot cycle this test will run when configured in.
+ * It will kick off a thread per CPU that will go into a loop
+ * writing to the per cpu ring buffer various sizes of data.
+ * Some of the data will be large items, some small.
+ *
+ * Another thread is created that goes into a spin, sending out
+ * IPIs to the other CPUs to also write into the ring buffer.
+ * this is to test the nesting ability of the buffer.
+ *
+ * Basic stats are recorded and reported. If something in the
+ * ring buffer should happen that's not expected, a big warning
+ * is displayed and all ring buffers are disabled.
+ */
+static struct task_struct *rb_threads[NR_CPUS] __initdata;
+
+struct rb_test_data {
+	struct ring_buffer	*buffer;
+	unsigned long		events;
+	unsigned long		bytes_written;
+	unsigned long		bytes_alloc;
+	unsigned long		bytes_dropped;
+	unsigned long		events_nested;
+	unsigned long		bytes_written_nested;
+	unsigned long		bytes_alloc_nested;
+	unsigned long		bytes_dropped_nested;
+	int			min_size_nested;
+	int			max_size_nested;
+	int			max_size;
+	int			min_size;
+	int			cpu;
+	int			cnt;
+};
+
+static struct rb_test_data rb_data[NR_CPUS] __initdata;
+
+/* 1 meg per cpu */
+#define RB_TEST_BUFFER_SIZE	1048576
+
+static char rb_string[] __initdata =
+	"abcdefghijklmnopqrstuvwxyz1234567890!@#$%^&*()?+\\"
+	"?+|:';\",.<>/?abcdefghijklmnopqrstuvwxyz1234567890"
+	"!@#$%^&*()?+\\?+|:';\",.<>/?abcdefghijklmnopqrstuv";
+
+static bool rb_test_started __initdata;
+
+struct rb_item {
+	int size;
+	char str[];
+};
+
+static __init int rb_write_something(struct rb_test_data *data, bool nested)
+{
+	struct ring_buffer_event *event;
+	struct rb_item *item;
+	bool started;
+	int event_len;
+	int size;
+	int len;
+	int cnt;
+
+	/* Have nested writes different that what is written */
+	cnt = data->cnt + (nested ? 27 : 0);
+
+	/* Multiply cnt by ~e, to make some unique increment */
+	size = (data->cnt * 68 / 25) % (sizeof(rb_string) - 1);
+
+	len = size + sizeof(struct rb_item);
+
+	started = rb_test_started;
+	/* read rb_test_started before checking buffer enabled */
+	smp_rmb();
+
+	event = ring_buffer_lock_reserve(data->buffer, len);
+	if (!event) {
+		/* Ignore dropped events before test starts. */
+		if (started) {
+			if (nested)
+				data->bytes_dropped += len;
+			else
+				data->bytes_dropped_nested += len;
+		}
+		return len;
+	}
+
+	event_len = ring_buffer_event_length(event);
+
+	if (RB_WARN_ON(data->buffer, event_len < len))
+		goto out;
+
+	item = ring_buffer_event_data(event);
+	item->size = size;
+	memcpy(item->str, rb_string, size);
+
+	if (nested) {
+		data->bytes_alloc_nested += event_len;
+		data->bytes_written_nested += len;
+		data->events_nested++;
+		if (!data->min_size_nested || len < data->min_size_nested)
+			data->min_size_nested = len;
+		if (len > data->max_size_nested)
+			data->max_size_nested = len;
+	} else {
+		data->bytes_alloc += event_len;
+		data->bytes_written += len;
+		data->events++;
+		if (!data->min_size || len < data->min_size)
+			data->max_size = len;
+		if (len > data->max_size)
+			data->max_size = len;
+	}
+
+ out:
+	ring_buffer_unlock_commit(data->buffer, event);
+
+	return 0;
+}
+
+static __init int rb_test(void *arg)
+{
+	struct rb_test_data *data = arg;
+
+	while (!kthread_should_stop()) {
+		rb_write_something(data, false);
+		data->cnt++;
+
+		set_current_state(TASK_INTERRUPTIBLE);
+		/* Now sleep between a min of 100-300us and a max of 1ms */
+		usleep_range(((data->cnt % 3) + 1) * 100, 1000);
+	}
+
+	return 0;
+}
+
+static __init void rb_ipi(void *ignore)
+{
+	struct rb_test_data *data;
+	int cpu = smp_processor_id();
+
+	data = &rb_data[cpu];
+	rb_write_something(data, true);
+}
+
+static __init int rb_hammer_test(void *arg)
+{
+	while (!kthread_should_stop()) {
+
+		/* Send an IPI to all cpus to write data! */
+		smp_call_function(rb_ipi, NULL, 1);
+		/* No sleep, but for non preempt, let others run */
+		schedule();
+	}
+
+	return 0;
+}
+
+static __init int test_ringbuffer(void)
+{
+	struct task_struct *rb_hammer;
+	struct ring_buffer *buffer;
+	int cpu;
+	int ret = 0;
+
+	pr_info("Running ring buffer tests...\n");
+
+	buffer = ring_buffer_alloc(RB_TEST_BUFFER_SIZE, RB_FL_OVERWRITE);
+	if (WARN_ON(!buffer))
+		return 0;
+
+	/* Disable buffer so that threads can't write to it yet */
+	ring_buffer_record_off(buffer);
+
+	for_each_online_cpu(cpu) {
+		rb_data[cpu].buffer = buffer;
+		rb_data[cpu].cpu = cpu;
+		rb_data[cpu].cnt = cpu;
+		rb_threads[cpu] = kthread_create(rb_test, &rb_data[cpu],
+						 "rbtester/%d", cpu);
+		if (WARN_ON(!rb_threads[cpu])) {
+			pr_cont("FAILED\n");
+			ret = -1;
+			goto out_free;
+		}
+
+		kthread_bind(rb_threads[cpu], cpu);
+ 		wake_up_process(rb_threads[cpu]);
+	}
+
+	/* Now create the rb hammer! */
+	rb_hammer = kthread_run(rb_hammer_test, NULL, "rbhammer");
+	if (WARN_ON(!rb_hammer)) {
+		pr_cont("FAILED\n");
+		ret = -1;
+		goto out_free;
+	}
+
+	ring_buffer_record_on(buffer);
+	/*
+	 * Show buffer is enabled before setting rb_test_started.
+	 * Yes there's a small race window where events could be
+	 * dropped and the thread wont catch it. But when a ring
+	 * buffer gets enabled, there will always be some kind of
+	 * delay before other CPUs see it. Thus, we don't care about
+	 * those dropped events. We care about events dropped after
+	 * the threads see that the buffer is active.
+	 */
+	smp_wmb();
+	rb_test_started = true;
+
+	set_current_state(TASK_INTERRUPTIBLE);
+	/* Just run for 10 seconds */;
+	schedule_timeout(10 * HZ);
+
+	kthread_stop(rb_hammer);
+
+ out_free:
+	for_each_online_cpu(cpu) {
+		if (!rb_threads[cpu])
+			break;
+		kthread_stop(rb_threads[cpu]);
+	}
+	if (ret) {
+		ring_buffer_free(buffer);
+		return ret;
+	}
+
+	/* Report! */
+	pr_info("finished\n");
+	for_each_online_cpu(cpu) {
+		struct ring_buffer_event *event;
+		struct rb_test_data *data = &rb_data[cpu];
+		struct rb_item *item;
+		unsigned long total_events;
+		unsigned long total_dropped;
+		unsigned long total_written;
+		unsigned long total_alloc;
+		unsigned long total_read = 0;
+		unsigned long total_size = 0;
+		unsigned long total_len = 0;
+		unsigned long total_lost = 0;
+		unsigned long lost;
+		int big_event_size;
+		int small_event_size;
+
+		ret = -1;
+
+		total_events = data->events + data->events_nested;
+		total_written = data->bytes_written + data->bytes_written_nested;
+		total_alloc = data->bytes_alloc + data->bytes_alloc_nested;
+		total_dropped = data->bytes_dropped + data->bytes_dropped_nested;
+
+		big_event_size = data->max_size + data->max_size_nested;
+		small_event_size = data->min_size + data->min_size_nested;
+
+		pr_info("CPU %d:\n", cpu);
+		pr_info("              events:    %ld\n", total_events);
+		pr_info("       dropped bytes:    %ld\n", total_dropped);
+		pr_info("       alloced bytes:    %ld\n", total_alloc);
+		pr_info("       written bytes:    %ld\n", total_written);
+		pr_info("       biggest event:    %d\n", big_event_size);
+		pr_info("      smallest event:    %d\n", small_event_size);
+
+		if (RB_WARN_ON(buffer, total_dropped))
+			break;
+
+		ret = 0;
+
+		while ((event = ring_buffer_consume(buffer, cpu, NULL, &lost))) {
+			total_lost += lost;
+			item = ring_buffer_event_data(event);
+			total_len += ring_buffer_event_length(event);
+			total_size += item->size + sizeof(struct rb_item);
+			if (memcmp(&item->str[0], rb_string, item->size) != 0) {
+				pr_info("FAILED!\n");
+				pr_info("buffer had: %.*s\n", item->size, item->str);
+				pr_info("expected:   %.*s\n", item->size, rb_string);
+				RB_WARN_ON(buffer, 1);
+				ret = -1;
+				break;
+			}
+			total_read++;
+		}
+		if (ret)
+			break;
+
+		ret = -1;
+
+		pr_info("         read events:   %ld\n", total_read);
+		pr_info("         lost events:   %ld\n", total_lost);
+		pr_info("        total events:   %ld\n", total_lost + total_read);
+		pr_info("  recorded len bytes:   %ld\n", total_len);
+		pr_info(" recorded size bytes:   %ld\n", total_size);
+		if (total_lost)
+			pr_info(" With dropped events, record len and size may not match\n"
+				" alloced and written from above\n");
+		if (!total_lost) {
+			if (RB_WARN_ON(buffer, total_len != total_alloc ||
+				       total_size != total_written))
+				break;
+		}
+		if (RB_WARN_ON(buffer, total_lost + total_read != total_events))
+			break;
+
+		ret = 0;
+	}
+	if (!ret)
+		pr_info("Ring buffer PASSED!\n");
+
+	ring_buffer_free(buffer);
+	return 0;
+}
+
+late_initcall(test_ringbuffer);
+#endif /* CONFIG_RING_BUFFER_STARTUP_TEST */

kernel/trace/trace.c

···
 /*
  * ring buffer based function tracer
  *
- * Copyright (C) 2007-2008 Steven Rostedt <[e-mail]>
+ * Copyright (C) 2007-2012 Steven Rostedt <[e-mail]>
  * Copyright (C) 2008 Ingo Molnar <[e-mail]>
  *
  * Originally taken from the RT patch by:
···
 #include <linux/seq_file.h>
 #include <linux/notifier.h>
 #include <linux/irqflags.h>
-#include <linux/irq_work.h>
 #include <linux/debugfs.h>
 #include <linux/pagemap.h>
 #include <linux/hardirq.h>
···
  * On boot up, the ring buffer is set to the minimum size, so that
  * we do not waste memory on systems that are not using tracing.
  */
-int ring_buffer_expanded;
+bool ring_buffer_expanded;
 
 /*
  * We need to change this state when a selftest is running.
···
 static DEFINE_PER_CPU(bool, trace_cmdline_save);
 
 /*
- * When a reader is waiting for data, then this variable is
- * set to true.
- */
-static bool trace_wakeup_needed;
-
-static struct irq_work trace_work_wakeup;
-
-/*
  * Kill all tracing for good (never come back).
  * It is initialized to 1 but will turn to zero if the initialization
  * of the tracer is successful. But that is the only place that sets
···
 static char bootup_tracer_buf[MAX_TRACER_SIZE] __initdata;
 static char *default_bootup_tracer;
 
+static bool allocate_snapshot;
+
 static int __init set_cmdline_ftrace(char *str)
 {
 	strlcpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
 	default_bootup_tracer = bootup_tracer_buf;
 	/* We are using ftrace early, expand it */
-	ring_buffer_expanded = 1;
+	ring_buffer_expanded = true;
 	return 1;
 }
 __setup("ftrace=", set_cmdline_ftrace);
···
         return 0;
 }
 __setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);
+
+static int __init boot_alloc_snapshot(char *str)
+{
+	allocate_snapshot = true;
+	/* We also need the main ring buffer expanded */
+	ring_buffer_expanded = true;
+	return 1;
+}
+__setup("alloc_snapshot", boot_alloc_snapshot);
 
 
 static char trace_boot_options_buf[MAX_TRACER_SIZE] __initdata;
···
  */
 static struct trace_array	global_trace;
 
-static DEFINE_PER_CPU(struct trace_array_cpu, global_trace_cpu);
+LIST_HEAD(ftrace_trace_arrays);
 
 int filter_current_check_discard(struct ring_buffer *buffer,
 				 struct ftrace_event_call *call, void *rec,
···
 	u64 ts;
 
 	/* Early boot up does not have a buffer yet */
-	if (!global_trace.buffer)
+	if (!global_trace.trace_buffer.buffer)
 		return trace_clock_local();
 
-	ts = ring_buffer_time_stamp(global_trace.buffer, cpu);
-	ring_buffer_normalize_time_stamp(global_trace.buffer, cpu, &ts);
+	ts = ring_buffer_time_stamp(global_trace.trace_buffer.buffer, cpu);
+	ring_buffer_normalize_time_stamp(global_trace.trace_buffer.buffer, cpu, &ts);
 
 	return ts;
 }
-
-/*
- * The max_tr is used to snapshot the global_trace when a maximum
- * latency is reached. Some tracers will use this to store a maximum
- * trace while it continues examining live traces.
- *
- * The buffers for the max_tr are set up the same as the global_trace.
- * When a snapshot is taken, the link list of the max_tr is swapped
- * with the link list of the global_trace and the buffers are reset for
- * the global_trace so the tracing can continue.
- */
-static struct trace_array	max_tr;
-
-static DEFINE_PER_CPU(struct trace_array_cpu, max_tr_data);
 
 int tracing_is_enabled(void)
 {
···
 
 /* trace_types holds a link list of available tracers. */
 static struct tracer		*trace_types __read_mostly;
-
-/* current_trace points to the tracer that is currently active */
-static struct tracer		*current_trace __read_mostly = &nop_trace;
 
 /*
  * trace_types_lock is used to protect the trace_types list.
···
 
 static inline void trace_access_lock(int cpu)
 {
-	if (cpu == TRACE_PIPE_ALL_CPU) {
+	if (cpu == RING_BUFFER_ALL_CPUS) {
 		/* gain it for accessing the whole ring buffer. */
 		down_write(&all_cpu_access_lock);
 	} else {
 		/* gain it for accessing a cpu ring buffer. */
 
-		/* Firstly block other trace_access_lock(TRACE_PIPE_ALL_CPU). */
+		/* Firstly block other trace_access_lock(RING_BUFFER_ALL_CPUS). */
 		down_read(&all_cpu_access_lock);
 
 		/* Secondly block other access to this @cpu ring buffer. */
···
 
 static inline void trace_access_unlock(int cpu)
 {
-	if (cpu == TRACE_PIPE_ALL_CPU) {
+	if (cpu == RING_BUFFER_ALL_CPUS) {
 		up_write(&all_cpu_access_lock);
 	} else {
 		mutex_unlock(&per_cpu(cpu_access_lock, cpu));
···
 
 #endif
 
-/* trace_wait is a waitqueue for tasks blocked on trace_poll */
-static DECLARE_WAIT_QUEUE_HEAD(trace_wait);
-
 /* trace_flags holds trace_options default values */
 unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
 	TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO | TRACE_ITER_SLEEP_TIME |
 	TRACE_ITER_GRAPH_TIME | TRACE_ITER_RECORD_CMD | TRACE_ITER_OVERWRITE |
-	TRACE_ITER_IRQ_INFO | TRACE_ITER_MARKERS;
-
-static int trace_stop_count;
-static DEFINE_RAW_SPINLOCK(tracing_start_lock);
-
-/**
- * trace_wake_up - wake up tasks waiting for trace input
- *
- * Schedules a delayed work to wake up any task that is blocked on the
- * trace_wait queue. These is used with trace_poll for tasks polling the
- * trace.
- */
-static void trace_wake_up(struct irq_work *work)
-{
-	wake_up_all(&trace_wait);
-
-}
+	TRACE_ITER_IRQ_INFO | TRACE_ITER_MARKERS | TRACE_ITER_FUNCTION;
 
 /**
  * tracing_on - enable tracing buffers
···
  */
 void tracing_on(void)
 {
-	if (global_trace.buffer)
-		ring_buffer_record_on(global_trace.buffer);
+	if (global_trace.trace_buffer.buffer)
+		ring_buffer_record_on(global_trace.trace_buffer.buffer);
 	/*
 	 * This flag is only looked at when buffers haven't been
 	 * allocated yet. We don't really care about the race
···
 EXPORT_SYMBOL_GPL(tracing_on);
 
 /**
+ * __trace_puts - write a constant string into the trace buffer.
+ * @ip:	   The address of the caller
+ * @str:   The constant string to write
+ * @size:  The size of the string.
+ */
+int __trace_puts(unsigned long ip, const char *str, int size)
+{
+	struct ring_buffer_event *event;
+	struct ring_buffer *buffer;
+	struct print_entry *entry;
+	unsigned long irq_flags;
+	int alloc;
+
+	alloc = sizeof(*entry) + size + 2; /* possible \n added */
+
+	local_save_flags(irq_flags);
+	buffer = global_trace.trace_buffer.buffer;
+	event = trace_buffer_lock_reserve(buffer, TRACE_PRINT, alloc, 
+					  irq_flags, preempt_count());
+	if (!event)
+		return 0;
+
+	entry = ring_buffer_event_data(event);
+	entry->ip = ip;
+
+	memcpy(&entry->buf, str, size);
+
+	/* Add a newline if necessary */
+	if (entry->buf[size - 1] != '\n') {
+		entry->buf[size] = '\n';
+		entry->buf[size + 1] = '\0';
+	} else
+		entry->buf[size] = '\0';
+
+	__buffer_unlock_commit(buffer, event);
+
+	return size;
+}
+EXPORT_SYMBOL_GPL(__trace_puts);
+
+/**
+ * __trace_bputs - write the pointer to a constant string into trace buffer
+ * @ip:	   The address of the caller
+ * @str:   The constant string to write to the buffer to
+ */
+int __trace_bputs(unsigned long ip, const char *str)
+{
+	struct ring_buffer_event *event;
+	struct ring_buffer *buffer;
+	struct bputs_entry *entry;
+	unsigned long irq_flags;
+	int size = sizeof(struct bputs_entry);
+
+	local_save_flags(irq_flags);
+	buffer = global_trace.trace_buffer.buffer;
+	event = trace_buffer_lock_reserve(buffer, TRACE_BPUTS, size,
+					  irq_flags, preempt_count());
+	if (!event)
+		return 0;
+
+	entry = ring_buffer_event_data(event);
+	entry->ip			= ip;
+	entry->str			= str;
+
+	__buffer_unlock_commit(buffer, event);
+
+	return 1;
+}
+EXPORT_SYMBOL_GPL(__trace_bputs);
+
+#ifdef CONFIG_TRACER_SNAPSHOT
+/**
+ * trace_snapshot - take a snapshot of the current buffer.
+ *
+ * This causes a swap between the snapshot buffer and the current live
+ * tracing buffer. You can use this to take snapshots of the live
+ * trace when some condition is triggered, but continue to trace.
+ *
+ * Note, make sure to allocate the snapshot with either
+ * a tracing_snapshot_alloc(), or by doing it manually
+ * with: echo 1 > /sys/kernel/debug/tracing/snapshot
+ *
+ * If the snapshot buffer is not allocated, it will stop tracing.
+ * Basically making a permanent snapshot.
+ */
+void tracing_snapshot(void)
+{
+	struct trace_array *tr = &global_trace;
+	struct tracer *tracer = tr->current_trace;
+	unsigned long flags;
+
+	if (in_nmi()) {
+		internal_trace_puts("*** SNAPSHOT CALLED FROM NMI CONTEXT ***\n");
+		internal_trace_puts("*** snapshot is being ignored        ***\n");
+		return;
+	}
+
+	if (!tr->allocated_snapshot) {
+		internal_trace_puts("*** SNAPSHOT NOT ALLOCATED ***\n");
+		internal_trace_puts("*** stopping trace here!   ***\n");
+		tracing_off();
+		return;
+	}
+
+	/* Note, snapshot can not be used when the tracer uses it */
+	if (tracer->use_max_tr) {
+		internal_trace_puts("*** LATENCY TRACER ACTIVE ***\n");
+		internal_trace_puts("*** Can not use snapshot (sorry) ***\n");
+		return;
+	}
+
+	local_irq_save(flags);
+	update_max_tr(tr, current, smp_processor_id());
+	local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(tracing_snapshot);
+
+static int resize_buffer_duplicate_size(struct trace_buffer *trace_buf,
+					struct trace_buffer *size_buf, int cpu_id);
+static void set_buffer_entries(struct trace_buffer *buf, unsigned long val);
+
+static int alloc_snapshot(struct trace_array *tr)
+{
+	int ret;
+
+	if (!tr->allocated_snapshot) {
+
+		/* allocate spare buffer */
+		ret = resize_buffer_duplicate_size(&tr->max_buffer,
+				   &tr->trace_buffer, RING_BUFFER_ALL_CPUS);
+		if (ret < 0)
+			return ret;
+
+		tr->allocated_snapshot = true;
+	}
+
+	return 0;
+}
+
+void free_snapshot(struct trace_array *tr)
+{
+	/*
+	 * We don't free the ring buffer. instead, resize it because
+	 * The max_tr ring buffer has some state (e.g. ring->clock) and
+	 * we want preserve it.
+	 */
+	ring_buffer_resize(tr->max_buffer.buffer, 1, RING_BUFFER_ALL_CPUS);
+	set_buffer_entries(&tr->max_buffer, 1);
+	tracing_reset_online_cpus(&tr->max_buffer);
+	tr->allocated_snapshot = false;
+}
+
+/**
+ * trace_snapshot_alloc - allocate and take a snapshot of the current buffer.
+ *
+ * This is similar to trace_snapshot(), but it will allocate the
+ * snapshot buffer if it isn't already allocated. Use this only
+ * where it is safe to sleep, as the allocation may sleep.
+ *
+ * This causes a swap between the snapshot buffer and the current live
+ * tracing buffer. You can use this to take snapshots of the live
+ * trace when some condition is triggered, but continue to trace.
+ */
+void tracing_snapshot_alloc(void)
+{
+	struct trace_array *tr = &global_trace;
+	int ret;
+
+	ret = alloc_snapshot(tr);
+	if (WARN_ON(ret < 0))
+		return;
+
+	tracing_snapshot();
+}
+EXPORT_SYMBOL_GPL(tracing_snapshot_alloc);
+#else
+void tracing_snapshot(void)
+{
+	WARN_ONCE(1, "Snapshot feature not enabled, but internal snapshot used");
+}
+EXPORT_SYMBOL_GPL(tracing_snapshot);
+void tracing_snapshot_alloc(void)
+{
+	/* Give warning */
+	tracing_snapshot();
+}
+EXPORT_SYMBOL_GPL(tracing_snapshot_alloc);
+#endif /* CONFIG_TRACER_SNAPSHOT */
+
+/**
  * tracing_off - turn off tracing buffers
  *
  * This function stops the tracing buffers from recording data.
···
  */
 void tracing_off(void)
 {
-	if (global_trace.buffer)
-		ring_buffer_record_off(global_trace.buffer);
+	if (global_trace.trace_buffer.buffer)
+		ring_buffer_record_off(global_trace.trace_buffer.buffer);
 	/*
 	 * This flag is only looked at when buffers haven't been
 	 * allocated yet. We don't really care about the race
···
  */
 int tracing_is_on(void)
 {
-	if (global_trace.buffer)
-		return ring_buffer_record_is_on(global_trace.buffer);
+	if (global_trace.trace_buffer.buffer)
+		return ring_buffer_record_is_on(global_trace.trace_buffer.buffer);
 	return !global_trace.buffer_disabled;
 }
 EXPORT_SYMBOL_GPL(tracing_is_on);
···
 	"disable_on_free",
 	"irq-info",
 	"markers",
+	"function-trace",
 	NULL
 };
 
···
 	{ trace_clock_local,	"local",	1 },
 	{ trace_clock_global,	"global",	1 },
 	{ trace_clock_counter,	"counter",	0 },
+	{ trace_clock_jiffies,	"uptime",	1 },
+	{ trace_clock,		"perf",		1 },
 	ARCH_TRACE_CLOCKS
 };
 
···
 static void
 __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 {
-	struct trace_array_cpu *data = tr->data[cpu];
-	struct trace_array_cpu *max_data;
+	struct trace_buffer *trace_buf = &tr->trace_buffer;
+	struct trace_buffer *max_buf = &tr->max_buffer;
+	struct trace_array_cpu *data = per_cpu_ptr(trace_buf->data, cpu);
+	struct trace_array_cpu *max_data = per_cpu_ptr(max_buf->data, cpu);
 
-	max_tr.cpu = cpu;
-	max_tr.time_start = data->preempt_timestamp;
+	max_buf->cpu = cpu;
+	max_buf->time_start = data->preempt_timestamp;
 
-	max_data = max_tr.data[cpu];
 	max_data->saved_latency = tracing_max_latency;
 	max_data->critical_start = data->critical_start;
 	max_data->critical_end = data->critical_end;
···
 {
 	struct ring_buffer *buf;
 
-	if (trace_stop_count)
+	if (tr->stop_count)
 		return;
 
 	WARN_ON_ONCE(!irqs_disabled());
 
-	if (!current_trace->allocated_snapshot) {
+	if (!tr->allocated_snapshot) {
 		/* Only the nop tracer should hit this when disabling */
-		WARN_ON_ONCE(current_trace != &nop_trace);
+		WARN_ON_ONCE(tr->current_trace != &nop_trace);
 		return;
 	}
 
 	arch_spin_lock(&ftrace_max_lock);
 
-	buf = tr->buffer;
-	tr->buffer = max_tr.buffer;
-	max_tr.buffer = buf;
+	buf = tr->trace_buffer.buffer;
+	tr->trace_buffer.buffer = tr->max_buffer.buffer;
+	tr->max_buffer.buffer = buf;
 
 	__update_max_tr(tr, tsk, cpu);
 	arch_spin_unlock(&ftrace_max_lock);
···
 {
 	int ret;
 
-	if (trace_stop_count)
+	if (tr->stop_count)
 		return;
 
 	WARN_ON_ONCE(!irqs_disabled());
-	if (!current_trace->allocated_snapshot) {
+	if (tr->allocated_snapshot) {
 		/* Only the nop tracer should hit this when disabling */
-		WARN_ON_ONCE(current_trace != &nop_trace);
+		WARN_ON_ONCE(tr->current_trace != &nop_trace);
 		return;
 	}
 
 	arch_spin_lock(&ftrace_max_lock);
 
-	ret = ring_buffer_swap_cpu(max_tr.buffer, tr->buffer, cpu);
+	ret = ring_buffer_swap_cpu(tr->max_buffer.buffer, tr->trace_buffer.buffer, cpu);
 
 	if (ret == -EBUSY) {
 		/*
···
 		 * the max trace buffer (no one writes directly to it)
 		 * and flag that it failed.
 		 */
-		trace_array_printk(&max_tr, _THIS_IP_,
+		trace_array_printk_buf(tr->max_buffer.buffer, _THIS_IP_,
 			"Failed to swap buffers due to commit in progress\n");
 	}
 
···
 
 static void default_wait_pipe(struct trace_iterator *iter)
 {
-	DEFINE_WAIT(wait);
+	/* Iterators are static, they should be filled or empty */
+	if (trace_buffer_iter(iter, iter->cpu_file))
+		return;
 
-	prepare_to_wait(&trace_wait, &wait, TASK_INTERRUPTIBLE);
+	ring_buffer_wait(iter->trace_buffer->buffer, iter->cpu_file);
+}
+
+#ifdef CONFIG_FTRACE_STARTUP_TEST
+static int run_tracer_selftest(struct tracer *type)
+{
+	struct trace_array *tr = &global_trace;
+	struct tracer *saved_tracer = tr->current_trace;
+	int ret;
+
+	if (!type->selftest || tracing_selftest_disabled)
+		return 0;
 
 	/*
-	 * The events can happen in critical sections where
-	 * checking a work queue can cause deadlocks.
-	 * After adding a task to the queue, this flag is set
-	 * only to notify events to try to wake up the queue
-	 * using irq_work.
-	 *
-	 * We don't clear it even if the buffer is no longer
-	 * empty. The flag only causes the next event to run
-	 * irq_work to do the work queue wake up. The worse
-	 * that can happen if we race with !trace_empty() is that
-	 * an event will cause an irq_work to try to wake up
-	 * an empty queue.
-	 *
-	 * There's no reason to protect this flag either, as
-	 * the work queue and irq_work logic will do the necessary
-	 * synchronization for the wake ups. The only thing
-	 * that is necessary is that the wake up happens after
-	 * a task has been queued. It's OK for spurious wake ups.
+	 * Run a selftest on this tracer.
+	 * Here we reset the trace buffer, and set the current
+	 * tracer to be this tracer. The tracer can then run some
+	 * internal tracing to verify that everything is in order.
+	 * If we fail, we do not register this tracer.
 	 */
-	trace_wakeup_needed = true;
+	tracing_reset_online_cpus(&tr->trace_buffer);
 
-	if (trace_empty(iter))
-		schedule();
+	tr->current_trace = type;
 
-	finish_wait(&trace_wait, &wait);
+#ifdef CONFIG_TRACER_MAX_TRACE
+	if (type->use_max_tr) {
+		/* If we expanded the buffers, make sure the max is expanded too */
+		if (ring_buffer_expanded)
+			ring_buffer_resize(tr->max_buffer.buffer, trace_buf_size,
+					   RING_BUFFER_ALL_CPUS);
+		tr->allocated_snapshot = true;
+	}
+#endif
+
+	/* the test is responsible for initializing and enabling */
+	pr_info("Testing tracer %s: ", type->name);
+	ret = type->selftest(type, tr);
+	/* the test is responsible for resetting too */
+	tr->current_trace = saved_tracer;
+	if (ret) {
+		printk(KERN_CONT "FAILED!\n");
+		/* Add the warning after printing 'FAILED' */
+		WARN_ON(1);
+		return -1;
+	}
+	/* Only reset on passing, to avoid touching corrupted buffers */
+	tracing_reset_online_cpus(&tr->trace_buffer);
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+	if (type->use_max_tr) {
+		tr->allocated_snapshot = false;
+
+		/* Shrink the max buffer again */
+		if (ring_buffer_expanded)
+			ring_buffer_resize(tr->max_buffer.buffer, 1,
+					   RING_BUFFER_ALL_CPUS);
+	}
+#endif
+
+	printk(KERN_CONT "PASSED\n");
+	return 0;
 }
+#else
+static inline int run_tracer_selftest(struct tracer *type)
+{
+	return 0;
+}
+#endif /* CONFIG_FTRACE_STARTUP_TEST */
 
 /**
  * register_tracer - register a tracer with the ftrace system.
···
 	if (!type->wait_pipe)
 		type->wait_pipe = default_wait_pipe;
 
-
-#ifdef CONFIG_FTRACE_STARTUP_TEST
-	if (type->selftest && !tracing_selftest_disabled) {
-		struct tracer *saved_tracer = current_trace;
-		struct trace_array *tr = &global_trace;
-
-		/*
-		 * Run a selftest on this tracer.
-		 * Here we reset the trace buffer, and set the current
-		 * tracer to be this tracer. The tracer can then run some
-		 * internal tracing to verify that everything is in order.
-		 * If we fail, we do not register this tracer.
-		 */
-		tracing_reset_online_cpus(tr);
-
-		current_trace = type;
-
-		if (type->use_max_tr) {
-			/* If we expanded the buffers, make sure the max is expanded too */
-			if (ring_buffer_expanded)
-				ring_buffer_resize(max_tr.buffer, trace_buf_size,
-						   RING_BUFFER_ALL_CPUS);
-			type->allocated_snapshot = true;
-		}
-
-		/* the test is responsible for initializing and enabling */
-		pr_info("Testing tracer %s: ", type->name);
-		ret = type->selftest(type, tr);
-		/* the test is responsible for resetting too */
-		current_trace = saved_tracer;
-		if (ret) {
-			printk(KERN_CONT "FAILED!\n");
-			/* Add the warning after printing 'FAILED' */
-			WARN_ON(1);
-			goto out;
-		}
-		/* Only reset on passing, to avoid touching corrupted buffers */
-		tracing_reset_online_cpus(tr);
-
-		if (type->use_max_tr) {
-			type->allocated_snapshot = false;
-
-			/* Shrink the max buffer again */
-			if (ring_buffer_expanded)
-				ring_buffer_resize(max_tr.buffer, 1,
-						   RING_BUFFER_ALL_CPUS);
-		}
-
-		printk(KERN_CONT "PASSED\n");
-	}
-#endif
+	ret = run_tracer_selftest(type);
+	if (ret < 0)
+		goto out;
 
 	type->next = trace_types;
 	trace_types = type;
···
 	tracing_set_tracer(type->name);
 	default_bootup_tracer = NULL;
 	/* disable other selftests, since this will break it. */
-	tracing_selftest_disabled = 1;
+	tracing_selftest_disabled = true;
 #ifdef CONFIG_FTRACE_STARTUP_TEST
 	printk(KERN_INFO "Disabling FTRACE selftests due to running tracer '%s'\n",
 	       type->name);
···
 	return ret;
 }
 
-void tracing_reset(struct trace_array *tr, int cpu)
+void tracing_reset(struct trace_buffer *buf, int cpu)
 {
-	struct ring_buffer *buffer = tr->buffer;
+	struct ring_buffer *buffer = buf->buffer;
 
 	if (!buffer)
 		return;
···
 	ring_buffer_record_enable(buffer);
 }
 
-void tracing_reset_online_cpus(struct trace_array *tr)
+void tracing_reset_online_cpus(struct trace_buffer *buf)
 {
-	struct ring_buffer *buffer = tr->buffer;
+	struct ring_buffer *buffer = buf->buffer;
 	int cpu;
 
 	if (!buffer)
···
 	/* Make sure all commits have finished */
 	synchronize_sched();
 
-	tr->time_start = ftrace_now(tr->cpu);
+	buf->time_start = ftrace_now(buf->cpu);
 
 	for_each_online_cpu(cpu)
 		ring_buffer_reset_cpu(buffer, cpu);
···
 
 void tracing_reset_current(int cpu)
 {
-	tracing_reset(&global_trace, cpu);
+	tracing_reset(&global_trace.trace_buffer, cpu);
 }
 
-void tracing_reset_current_online_cpus(void)
+void tracing_reset_all_online_cpus(void)
 {
-	tracing_reset_online_cpus(&global_trace);
+	struct trace_array *tr;
+
+	mutex_lock(&trace_types_lock);
+	list_for_each_entry(tr, &ftrace_trace_arrays, list) {
+		tracing_reset_online_cpus(&tr->trace_buffer);
+#ifdef CONFIG_TRACER_MAX_TRACE
+		tracing_reset_online_cpus(&tr->max_buffer);
+#endif
+	}
+	mutex_unlock(&trace_types_lock);
 }
 
 #define SAVED_CMDLINES 128
···
 
 int is_tracing_stopped(void)
 {
-	return trace_stop_count;
+	return global_trace.stop_count;
 }
 
 /**
···
 	if (tracing_disabled)
 		return;
 
-	raw_spin_lock_irqsave(&tracing_start_lock, flags);
-	if (--trace_stop_count) {
-		if (trace_stop_count < 0) {
+	raw_spin_lock_irqsave(&global_trace.start_lock, flags);
+	if (--global_trace.stop_count) {
+		if (global_trace.stop_count < 0) {
 			/* Someone screwed up their debugging */
 			WARN_ON_ONCE(1);
-			trace_stop_count = 0;
+			global_trace.stop_count = 0;
 		}
 		goto out;
 	}
···
 	/* Prevent the buffers from switching */
 	arch_spin_lock(&ftrace_max_lock);
 
-	buffer = global_trace.buffer;
+	buffer = global_trace.trace_buffer.buffer;
 	if (buffer)
 		ring_buffer_record_enable(buffer);
 
-	buffer = max_tr.buffer;
+#ifdef CONFIG_TRACER_MAX_TRACE
+	buffer = global_trace.max_buffer.buffer;
 	if (buffer)
 		ring_buffer_record_enable(buffer);
+#endif
 
 	arch_spin_unlock(&ftrace_max_lock);
 
 	ftrace_start();
  out:
-	raw_spin_unlock_irqrestore(&tracing_start_lock, flags);
+	raw_spin_unlock_irqrestore(&global_trace.start_lock, flags);
+}
+
+static void tracing_start_tr(struct trace_array *tr)
+{
+	struct ring_buffer *buffer;
+	unsigned long flags;
+
+	if (tracing_disabled)
+		return;
+
+	/* If global, we need to also start the max tracer */
+	if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
+		return tracing_start();
+
+	raw_spin_lock_irqsave(&tr->start_lock, flags);
+
+	if (--tr->stop_count) {
+		if (tr->stop_count < 0) {
+			/* Someone screwed up their debugging */
+			WARN_ON_ONCE(1);
+			tr->stop_count = 0;
+		}
+		goto out;
+	}
+
+	buffer = tr->trace_buffer.buffer;
+	if (buffer)
+		ring_buffer_record_enable(buffer);
+
+ out:
+	raw_spin_unlock_irqrestore(&tr->start_lock, flags);
 }
 
 /**
···
 	unsigned long flags;
 
 	ftrace_stop();
-	raw_spin_lock_irqsave(&tracing_start_lock, flags);
-	if (trace_stop_count++)
+	raw_spin_lock_irqsave(&global_trace.start_lock, flags);
+	if (global_trace.stop_count++)
 		goto out;
 
 	/* Prevent the buffers from switching */
 	arch_spin_lock(&ftrace_max_lock);
 
-	buffer = global_trace.buffer;
+	buffer = global_trace.trace_buffer.buffer;
 	if (buffer)
 		ring_buffer_record_disable(buffer);
 
-	buffer = max_tr.buffer;
+#ifdef CONFIG_TRACER_MAX_TRACE
+	buffer = global_trace.max_buffer.buffer;
 	if (buffer)
 		ring_buffer_record_disable(buffer);
+#endif
 
 	arch_spin_unlock(&ftrace_max_lock);
 
  out:
-	raw_spin_unlock_irqrestore(&tracing_start_lock, flags);
+	raw_spin_unlock_irqrestore(&global_trace.start_lock, flags);
+}
+
+static void tracing_stop_tr(struct trace_array *tr)
+{
+	struct ring_buffer *buffer;
+	unsigned long flags;
+
+	/* If global, we need to also stop the max tracer */
+	if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
+		return tracing_stop();
+
+	raw_spin_lock_irqsave(&tr->start_lock, flags);
+	if (tr->stop_count++)
+		goto out;
+
+	buffer = tr->trace_buffer.buffer;
+	if (buffer)
+		ring_buffer_record_disable(buffer);
+
+ out:
+	raw_spin_unlock_irqrestore(&tr->start_lock, flags);
 }
 
 void trace_stop_cmdline_recording(void);
···
 __buffer_unlock_commit(struct ring_buffer *buffer, struct ring_buffer_event *event)
 {
 	__this_cpu_write(trace_cmdline_save, true);
-	if (trace_wakeup_needed) {
-		trace_wakeup_needed = false;
-		/* irq_work_queue() supplies it's own memory barriers */
-		irq_work_queue(&trace_work_wakeup);
-	}
 	ring_buffer_unlock_commit(buffer, event);
 }
 
···
 EXPORT_SYMBOL_GPL(trace_buffer_unlock_commit);
 
 struct ring_buffer_event *
+trace_event_buffer_lock_reserve(struct ring_buffer **current_rb,
+			  struct ftrace_event_file *ftrace_file,
+			  int type, unsigned long len,
+			  unsigned long flags, int pc)
+{
+	*current_rb = ftrace_file->tr->trace_buffer.buffer;
+	return trace_buffer_lock_reserve(*current_rb,
+					 type, len, flags, pc);
+}
+EXPORT_SYMBOL_GPL(trace_event_buffer_lock_reserve);
+
+struct ring_buffer_event *
 trace_current_buffer_lock_reserve(struct ring_buffer **current_rb,
 				  int type, unsigned long len,
 				  unsigned long flags, int pc)
 {
-	*current_rb = global_trace.buffer;
+	*current_rb = global_trace.trace_buffer.buffer;
 	return trace_buffer_lock_reserve(*current_rb,
 					 type, len, flags, pc);
 }
···
 	       int pc)
 {
 	struct ftrace_event_call *call = &event_function;
-	struct ring_buffer *buffer = tr->buffer;
+	struct ring_buffer *buffer = tr->trace_buffer.buffer;
 	struct ring_buffer_event *event;
 	struct ftrace_entry *entry;
 
···
 void __trace_stack(struct trace_array *tr, unsigned long flags, int skip,
 		   int pc)
 {
-	__ftrace_trace_stack(tr->buffer, flags, skip, pc, NULL);
+	__ftrace_trace_stack(tr->trace_buffer.buffer, flags, skip, pc, NULL);
 }
 
 /**
  * trace_dump_stack - record a stack back trace in the trace buffer
+ * @skip: Number of functions to skip (helper handlers)
  */
-void trace_dump_stack(void)
+void trace_dump_stack(int skip)
 {
 	unsigned long flags;
 
···
 
 	local_save_flags(flags);
 
-	/* skipping 3 traces, seems to get us at the caller of this function */
-	__ftrace_trace_stack(global_trace.buffer, flags, 3, preempt_count(), NULL);
+	/*
+	 * Skip 3 more, seems to get us at the caller of
+	 * this function.
+	 */
+	skip += 3;
+	__ftrace_trace_stack(global_trace.trace_buffer.buffer,
+			     flags, skip, preempt_count(), NULL);
 }
 
 static DEFINE_PER_CPU(int, user_stack_count);
···
 	 * directly here. If the global_trace.buffer is already
 	 * allocated here, then this was called by module code.
 	 */
-	if (global_trace.buffer)
+	if (global_trace.trace_buffer.buffer)
 		tracing_start_cmdline_record();
 }
 
···
 
 	local_save_flags(flags);
 	size = sizeof(*entry) + sizeof(u32) * len;
-	buffer = tr->buffer;
+	buffer = tr->trace_buffer.buffer;
 	event = trace_buffer_lock_reserve(buffer, TRACE_BPRINT, size,
 					  flags, pc);
 	if (!event)
···
 }
 EXPORT_SYMBOL_GPL(trace_vbprintk);
 
-int trace_array_printk(struct trace_array *tr,
-		       unsigned long ip, const char *fmt, ...)
-{
-	int ret;
-	va_list ap;
-
-	if (!(trace_flags & TRACE_ITER_PRINTK))
-		return 0;
-
-	va_start(ap, fmt);
-	ret = trace_array_vprintk(tr, ip, fmt, ap);
-	va_end(ap);
-	return ret;
-}
-
-int trace_array_vprintk(struct trace_array *tr,
-			unsigned long ip, const char *fmt, va_list args)
+static int
+__trace_array_vprintk(struct ring_buffer *buffer,
+		      unsigned long ip, const char *fmt, va_list args)
 {
 	struct ftrace_event_call *call = &event_print;
 	struct ring_buffer_event *event;
-	struct ring_buffer *buffer;
 	int len = 0, size, pc;
 	struct print_entry *entry;
 	unsigned long flags;
···
 
 	local_save_flags(flags);
 	size = sizeof(*entry) + len + 1;
-	buffer = tr->buffer;
 	event = trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
 					  flags, pc);
 	if (!event)
···
 	unpause_graph_tracing();
 
 	return len;
+}
+
+int trace_array_vprintk(struct trace_array *tr,
+			unsigned long ip, const char *fmt, va_list args)
+{
+	return __trace_array_vprintk(tr->trace_buffer.buffer, ip, fmt, args);
+}
+
+int trace_array_printk(struct trace_array *tr,
+		       unsigned long ip, const char *fmt, ...)
+{
+	int ret;
+	va_list ap;
+
+	if (!(trace_flags & TRACE_ITER_PRINTK))
+		return 0;
+
+	va_start(ap, fmt);
+	ret = trace_array_vprintk(tr, ip, fmt, ap);
+	va_end(ap);
+	return ret;
+}
+
+int trace_array_printk_buf(struct ring_buffer *buffer,
+			   unsigned long ip, const char *fmt, ...)
+{
+	int ret;
+	va_list ap;
+
+	if (!(trace_flags & TRACE_ITER_PRINTK))
+		return 0;
+
+	va_start(ap, fmt);
+	ret = __trace_array_vprintk(buffer, ip, fmt, ap);
+	va_end(ap);
+	return ret;
 }
 
 int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
···
 	if (buf_iter)
 		event = ring_buffer_iter_peek(buf_iter, ts);
 	else
-		event = ring_buffer_peek(iter->tr->buffer, cpu, ts,
+		event = ring_buffer_peek(iter->trace_buffer->buffer, cpu, ts,
 					 lost_events);
 
 	if (event) {
···
 __find_next_entry(struct trace_iterator *iter, int *ent_cpu,
 		  unsigned long *missing_events, u64 *ent_ts)
 {
-	struct ring_buffer *buffer = iter->tr->buffer;
+	struct ring_buffer *buffer = iter->trace_buffer->buffer;
 	struct trace_entry *ent, *next = NULL;
 	unsigned long lost_events = 0, next_lost = 0;
 	int cpu_file = iter->cpu_file;
···
 	 * If we are in a per_cpu trace file, don't bother by iterating over
 	 * all cpu and peek directly.
 	 */
-	if (cpu_file > TRACE_PIPE_ALL_CPU) {
+	if (cpu_file > RING_BUFFER_ALL_CPUS) {
 		if (ring_buffer_empty_cpu(buffer, cpu_file))
 			return NULL;
 		ent = peek_next_entry(iter, cpu_file, ent_ts, missing_events);
···
 
 static void trace_consume(struct trace_iterator *iter)
 {
-	ring_buffer_consume(iter->tr->buffer, iter->cpu, &iter->ts,
+	ring_buffer_consume(iter->trace_buffer->buffer, iter->cpu, &iter->ts,
 			    &iter->lost_events);
 }
 
···
 
 void tracing_iter_reset(struct trace_iterator *iter, int cpu)
 {
-	struct trace_array *tr = iter->tr;
 	struct ring_buffer_event *event;
 	struct ring_buffer_iter *buf_iter;
 	unsigned long entries = 0;
 	u64 ts;
 
-	tr->data[cpu]->skipped_entries = 0;
+	per_cpu_ptr(iter->trace_buffer->data, cpu)->skipped_entries = 0;
 
 	buf_iter = trace_buffer_iter(iter, cpu);
 	if (!buf_iter)
···
 	 * by the timestamp being before the start of the buffer.
 	 */
 	while ((event = ring_buffer_iter_peek(buf_iter, &ts))) {
-		if (ts >= iter->tr->time_start)
+		if (ts >= iter->trace_buffer->time_start)
 			break;
 		entries++;
 		ring_buffer_read(buf_iter, NULL);
 	}
 
-	tr->data[cpu]->skipped_entries = entries;
+	per_cpu_ptr(iter->trace_buffer->data, cpu)->skipped_entries = entries;
 }
 
 /*
···
 static void *s_start(struct seq_file *m, loff_t *pos)
 {
 	struct trace_iterator *iter = m->private;
+	struct trace_array *tr = iter->tr;
 	int cpu_file = iter->cpu_file;
 	void *p = NULL;
 	loff_t l = 0;
···
 	 * will point to the same string as current_trace->name.
 	 */
 	mutex_lock(&trace_types_lock);
-	if (unlikely(current_trace && iter->trace->name != current_trace->name))
-		*iter->trace = *current_trace;
+	if (unlikely(tr->current_trace && iter->trace->name != tr->current_trace->name))
+		*iter->trace = *tr->current_trace;
 	mutex_unlock(&trace_types_lock);
 
+#ifdef CONFIG_TRACER_MAX_TRACE
 	if (iter->snapshot && iter->trace->use_max_tr)
 		return ERR_PTR(-EBUSY);
+#endif
 
 	if (!iter->snapshot)
 		atomic_inc(&trace_record_cmdline_disabled);
···
 		iter->cpu = 0;
 		iter->idx = -1;
 
-		if (cpu_file == TRACE_PIPE_ALL_CPU) {
+		if (cpu_file == RING_BUFFER_ALL_CPUS) {
 			for_each_tracing_cpu(cpu)
 				tracing_iter_reset(iter, cpu);
 		} else
···
 {
 	struct trace_iterator *iter = m->private;
 
+#ifdef CONFIG_TRACER_MAX_TRACE
 	if (iter->snapshot && iter->trace->use_max_tr)
 		return;
+#endif
 
 	if (!iter->snapshot)
 		atomic_dec(&trace_record_cmdline_disabled);
+
 	trace_access_unlock(iter->cpu_file);
 	trace_event_read_unlock();
 }
 
 static void
-get_total_entries(struct trace_array *tr, unsigned long *total, unsigned long *entries)
+get_total_entries(struct trace_buffer *buf,
+		  unsigned long *total, unsigned long *entries)
 {
 	unsigned long count;
 	int cpu;
···
 	*entries = 0;
 
 	for_each_tracing_cpu(cpu) {
-		count = ring_buffer_entries_cpu(tr->buffer, cpu);
+		count = ring_buffer_entries_cpu(buf->buffer, cpu);
 		/*
 		 * If this buffer has skipped entries, then we hold all
 		 * entries for the trace and we need to ignore the
 		 * ones before the time stamp.
 		 */
-		if (tr->data[cpu]->skipped_entries) {
-			count -= tr->data[cpu]->skipped_entries;
+		if (per_cpu_ptr(buf->data, cpu)->skipped_entries) {
+			count -= per_cpu_ptr(buf->data, cpu)->skipped_entries;
 			/* total is the same as the entries */
 			*total += count;
 		} else
 			*total += count +
-				ring_buffer_overrun_cpu(tr->buffer, cpu);
+				ring_buffer_overrun_cpu(buf->buffer, cpu);
 		*entries += count;
 	}
 }
···
 	seq_puts(m, "#     \\   /      |||||  \\    |   /           \n");
 }
 
-static void print_event_info(struct trace_array *tr, struct seq_file *m)
+static void print_event_info(struct trace_buffer *buf, struct seq_file *m)
 {
 	unsigned long total;
 	unsigned long entries;
 
-	get_total_entries(tr, &total, &entries);
+	get_total_entries(buf, &total, &entries);
 	seq_printf(m, "# entries-in-buffer/entries-written: %lu/%lu   #P:%d\n",
 		   entries, total, num_online_cpus());
 	seq_puts(m, "#\n");
 }
 
-static void print_func_help_header(struct trace_array *tr, struct seq_file *m)
+static void print_func_help_header(struct trace_buffer *buf, struct seq_file *m)
 {
-	print_event_info(tr, m);
+	print_event_info(buf, m);
 	seq_puts(m, "#           TASK-PID   CPU#      TIMESTAMP  FUNCTION\n");
 	seq_puts(m, "#              | |       |          |         |\n");
 }
 
-static void print_func_help_header_irq(struct trace_array *tr, struct seq_file *m)
+static void print_func_help_header_irq(struct trace_buffer *buf, struct seq_file *m)
 {
-	print_event_info(tr, m);
+	print_event_info(buf, m);
 	seq_puts(m, "#                              _-----=> irqs-off\n");
 	seq_puts(m, "#                             / _----=> need-resched\n");
 	seq_puts(m, "#                            | / _---=> hardirq/softirq\n");
···
 print_trace_header(struct seq_file *m, struct trace_iterator *iter)
 {
 	unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
-	struct trace_array *tr = iter->tr;
-	struct trace_array_cpu *data = tr->data[tr->cpu];
-	struct tracer *type = current_trace;
+	struct trace_buffer *buf = iter->trace_buffer;
+	struct trace_array_cpu *data = per_cpu_ptr(buf->data, buf->cpu);
+	struct tracer *type = iter->trace;
 	unsigned long entries;
 	unsigned long total;
 	const char *name = "preemption";
 
 	name = type->name;
 
-	get_total_entries(tr, &total, &entries);
+	get_total_entries(buf, &total, &entries);
 
 	seq_printf(m, "# %s latency trace v1.1.5 on %s\n",
 		   name, UTS_RELEASE);
···
 		   nsecs_to_usecs(data->saved_latency),
 		   entries,
 		   total,
-		   tr->cpu,
+		   buf->cpu,
 #if defined(CONFIG_PREEMPT_NONE)
 		   "server",
 #elif defined(CONFIG_PREEMPT_VOLUNTARY)
···
 	if (cpumask_test_cpu(iter->cpu, iter->started))
 		return;
 
-	if (iter->tr->data[iter->cpu]->skipped_entries)
+	if (per_cpu_ptr(iter->trace_buffer->data, iter->cpu)->skipped_entries)
 		return;
 
 	cpumask_set_cpu(iter->cpu, iter->started);
···
 	int cpu;
 
 	/* If we are looking at one CPU buffer, only check that one */
-	if (iter->cpu_file != TRACE_PIPE_ALL_CPU) {
+	if (iter->cpu_file != RING_BUFFER_ALL_CPUS) {
 		cpu = iter->cpu_file;
 		buf_iter = trace_buffer_iter(iter, cpu);
 		if (buf_iter) {
 			if (!ring_buffer_iter_empty(buf_iter))
 				return 0;
 		} else {
-			if (!ring_buffer_empty_cpu(iter->tr->buffer, cpu))
+			if (!ring_buffer_empty_cpu(iter->trace_buffer->buffer, cpu))
 				return 0;
 		}
 		return 1;
···
 			if (!ring_buffer_iter_empty(buf_iter))
 				return 0;
 		} else {
-			if (!ring_buffer_empty_cpu(iter->tr->buffer, cpu))
+			if (!ring_buffer_empty_cpu(iter->trace_buffer->buffer, cpu))
 				return 0;
 		}
 	}
···
 		if (ret != TRACE_TYPE_UNHANDLED)
 			return ret;
 	}
+
+	if (iter->ent->type == TRACE_BPUTS &&
+			trace_flags & TRACE_ITER_PRINTK &&
+			trace_flags & TRACE_ITER_PRINTK_MSGONLY)
+		return trace_print_bputs_msg_only(iter);
 
 	if (iter->ent->type == TRACE_BPRINT &&
 			trace_flags & TRACE_ITER_PRINTK &&
···
 	} else {
 		if (!(trace_flags & TRACE_ITER_VERBOSE)) {
 			if (trace_flags & TRACE_ITER_IRQ_INFO)
-				print_func_help_header_irq(iter->tr, m);
+				print_func_help_header_irq(iter->trace_buffer, m);
 			else
-				print_func_help_header(iter->tr, m);
+				print_func_help_header(iter->trace_buffer, m);
 		}
 	}
 }
···
 }
 
 #ifdef CONFIG_TRACER_MAX_TRACE
-static void print_snapshot_help(struct seq_file *m, struct trace_iterator *iter)
+static void show_snapshot_main_help(struct seq_file *m)
 {
-	if (iter->trace->allocated_snapshot)
-		seq_printf(m, "#\n# * Snapshot is allocated *\n#\n");
-	else
-		seq_printf(m, "#\n# * Snapshot is freed *\n#\n");
-
-	seq_printf(m, "# Snapshot commands:\n");
 	seq_printf(m, "# echo 0 > snapshot : Clears and frees snapshot buffer\n");
 	seq_printf(m, "# echo 1 > snapshot : Allocates snapshot buffer, if not already allocated.\n");
 	seq_printf(m, "#                      Takes a snapshot of the main buffer.\n");
 	seq_printf(m, "# echo 2 > snapshot : Clears snapshot buffer (but does not allocate)\n");
 	seq_printf(m, "#                      (Doesn't have to be '2' works with any number that\n");
 	seq_printf(m, "#                       is not a '0' or '1')\n");
+}
+
+static void show_snapshot_percpu_help(struct seq_file *m)
+{
+	seq_printf(m, "# echo 0 > snapshot : Invalid for per_cpu snapshot file.\n");
+#ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
+	seq_printf(m, "# echo 1 > snapshot : Allocates snapshot buffer, if not already allocated.\n");
+	seq_printf(m, "#                      Takes a snapshot of the main buffer for this cpu.\n");
+#else
+	seq_printf(m, "# echo 1 > snapshot : Not supported with this kernel.\n");
+	seq_printf(m, "#                     Must use main snapshot file to allocate.\n");
+#endif
+	seq_printf(m, "# echo 2 > snapshot : Clears this cpu's snapshot buffer (but does not allocate)\n");
+	seq_printf(m, "#                      (Doesn't have to be '2' works with any number that\n");
+	seq_printf(m, "#                       is not a '0' or '1')\n");
+}
+
+static void print_snapshot_help(struct seq_file *m, struct trace_iterator *iter)
+{
+	if (iter->tr->allocated_snapshot)
+		seq_printf(m, "#\n# * Snapshot is allocated *\n#\n");
+	else
+		seq_printf(m, "#\n# * Snapshot is freed *\n#\n");
+
+	seq_printf(m, "# Snapshot commands:\n");
+	if (iter->cpu_file == RING_BUFFER_ALL_CPUS)
+		show_snapshot_main_help(m);
+	else
+		show_snapshot_percpu_help(m);
 }
 #else
 /* Should never be called */
···
 static struct trace_iterator *
 __tracing_open(struct inode *inode, struct file *file, bool snapshot)
 {
-	long cpu_file = (long) inode->i_private;
+	struct trace_cpu *tc = inode->i_private;
+	struct trace_array *tr = tc->tr;
 	struct trace_iterator *iter;
 	int cpu;
 
···
 	if (!iter->trace)
 		goto fail;
 
-	*iter->trace = *current_trace;
+	*iter->trace = *tr->current_trace;
 
 	if (!zalloc_cpumask_var(&iter->started, GFP_KERNEL))
 		goto fail;
 
-	if (current_trace->print_max || snapshot)
-		iter->tr = &max_tr;
+	iter->tr = tr;
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+	/* Currently only the top directory has a snapshot */
+	if (tr->current_trace->print_max || snapshot)
+		iter->trace_buffer = &tr->max_buffer;
 	else
-		iter->tr = &global_trace;
+#endif
+		iter->trace_buffer = &tr->trace_buffer;
 	iter->snapshot = snapshot;
 	iter->pos = -1;
 	mutex_init(&iter->mutex);
-	iter->cpu_file = cpu_file;
+	iter->cpu_file = tc->cpu;
 
 	/* Notify the tracer early; before we stop tracing. */
 	if (iter->trace && iter->trace->open)
 		iter->trace->open(iter);
 
 	/* Annotate start of buffers if we had overruns */
-	if (ring_buffer_overruns(iter->tr->buffer))
+	if (ring_buffer_overruns(iter->trace_buffer->buffer))
 		iter->iter_flags |= TRACE_FILE_ANNOTATE;
 
 	/* Output in nanoseconds only if we are using a clock in nanoseconds. */
···
 
 	/* stop the trace while dumping if we are not opening "snapshot" */
 	if (!iter->snapshot)
-		tracing_stop();
+		tracing_stop_tr(tr);
 
-	if (iter->cpu_file == TRACE_PIPE_ALL_CPU) {
+	if (iter->cpu_file == RING_BUFFER_ALL_CPUS) {
 		for_each_tracing_cpu(cpu) {
 			iter->buffer_iter[cpu] =
-				ring_buffer_read_prepare(iter->tr->buffer, cpu);
+				ring_buffer_read_prepare(iter->trace_buffer->buffer, cpu);
 		}
 		ring_buffer_read_prepare_sync();
 		for_each_tracing_cpu(cpu) {
···
 	} else {
 		cpu = iter->cpu_file;
 		iter->buffer_iter[cpu] =
-			ring_buffer_read_prepare(iter->tr->buffer, cpu);
+			ring_buffer_read_prepare(iter->trace_buffer->buffer, cpu);
 		ring_buffer_read_prepare_sync();
 		ring_buffer_read_start(iter->buffer_iter[cpu]);
 		tracing_iter_reset(iter, cpu);
 	}
+
+	tr->ref++;
 
 	mutex_unlock(&trace_types_lock);
 
···
 {
 	struct seq_file *m = file->private_data;
 	struct trace_iterator *iter;
+	struct trace_array *tr;
 	int cpu;
 
 	if (!(file->f_mode & FMODE_READ))
 		return 0;
 
 	iter = m->private;
+	tr = iter->tr;
 
 	mutex_lock(&trace_types_lock);
+
+	WARN_ON(!tr->ref);
+	tr->ref--;
+
 	for_each_tracing_cpu(cpu) {
 		if (iter->buffer_iter[cpu])
 			ring_buffer_read_finish(iter->buffer_iter[cpu]);
···
 
 	if (!iter->snapshot)
 		/* reenable tracing if it was previously enabled */
-		tracing_start();
+		tracing_start_tr(tr);
 	mutex_unlock(&trace_types_lock);
 
 	mutex_destroy(&iter->mutex);
···
 	/* If this file was open for write, then erase contents */
 	if ((file->f_mode & FMODE_WRITE) &&
 	    (file->f_flags & O_TRUNC)) {
-		long cpu = (long) inode->i_private;
+		struct trace_cpu *tc = inode->i_private;
+		struct trace_array *tr = tc->tr;
 
-		if (cpu == TRACE_PIPE_ALL_CPU)
-			tracing_reset_online_cpus(&global_trace);
+		if (tc->cpu == RING_BUFFER_ALL_CPUS)
+			tracing_reset_online_cpus(&tr->trace_buffer);
 		else
-			tracing_reset(&global_trace, cpu);
+			tracing_reset(&tr->trace_buffer, tc->cpu);
 	}
 
 	if (file->f_mode & FMODE_READ) {
···
 tracing_cpumask_write(struct file *filp, const char __user *ubuf,
 		      size_t count, loff_t *ppos)
 {
-	int err, cpu;
+	struct trace_array *tr = filp->private_data;
 	cpumask_var_t tracing_cpumask_new;
+	int err, cpu;
 
 	if (!alloc_cpumask_var(&tracing_cpumask_new, GFP_KERNEL))
 		return -ENOMEM;
···
 		 */
 		if (cpumask_test_cpu(cpu, tracing_cpumask) &&
 				!cpumask_test_cpu(cpu, tracing_cpumask_new)) {
-			atomic_inc(&global_trace.data[cpu]->disabled);
-			ring_buffer_record_disable_cpu(global_trace.buffer, cpu);
+			atomic_inc(&per_cpu_ptr(tr->trace_buffer.data, cpu)->disabled);
+			ring_buffer_record_disable_cpu(tr->trace_buffer.buffer, cpu);
 		}
 		if (!cpumask_test_cpu(cpu, tracing_cpumask) &&
 				cpumask_test_cpu(cpu, tracing_cpumask_new)) {
-			atomic_dec(&global_trace.data[cpu]->disabled);
-			ring_buffer_record_enable_cpu(global_trace.buffer, cpu);
+			atomic_dec(&per_cpu_ptr(tr->trace_buffer.data, cpu)->disabled);
+			ring_buffer_record_enable_cpu(tr->trace_buffer.buffer, cpu);
 		}
 	}
 	arch_spin_unlock(&ftrace_max_lock);
···
 static int tracing_trace_options_show(struct seq_file *m, void *v)
 {
 	struct tracer_opt *trace_opts;
+	struct trace_array *tr = m->private;
 	u32 tracer_flags;
 	int i;
 
 	mutex_lock(&trace_types_lock);
-	tracer_flags = current_trace->flags->val;
-	trace_opts = current_trace->flags->opts;
+	tracer_flags = tr->current_trace->flags->val;
+	trace_opts = tr->current_trace->flags->opts;
 
 	for (i = 0; trace_options[i]; i++) {
 		if (trace_flags & (1 << i))
···
 	return 0;
 }
 
-int set_tracer_flag(unsigned int mask, int enabled)
+int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled)
 {
 	/* do nothing if flag is already set */
 	if (!!(trace_flags & mask) == !!enabled)
 		return 0;
 
 	/* Give the tracer a chance to approve the change */
-	if (current_trace->flag_changed)
-		if (current_trace->flag_changed(current_trace, mask, !!enabled))
+	if (tr->current_trace->flag_changed)
+		if (tr->current_trace->flag_changed(tr->current_trace, mask, !!enabled))
 			return -EINVAL;
 
 	if (enabled)
···
 		trace_event_enable_cmd_record(enabled);
 
 	if (mask == TRACE_ITER_OVERWRITE) {
-		ring_buffer_change_overwrite(global_trace.buffer, enabled);
+		ring_buffer_change_overwrite(tr->trace_buffer.buffer, enabled);
 #ifdef CONFIG_TRACER_MAX_TRACE
-		ring_buffer_change_overwrite(max_tr.buffer, enabled);
+		ring_buffer_change_overwrite(tr->max_buffer.buffer, enabled);
 #endif
 	}
 
···
 	return 0;
 }
 
-static int trace_set_options(char *option)
+static int trace_set_options(struct trace_array *tr, char *option)
 {
 	char *cmp;
 	int neg = 0;
···
 
 	for (i = 0; trace_options[i]; i++) {
 		if (strcmp(cmp, trace_options[i]) == 0) {
-			ret = set_tracer_flag(1 << i, !neg);
+			ret = set_tracer_flag(tr, 1 << i, !neg);
 			break;
 		}
 	}
 
 	/* If no option could be set, test the specific tracer options */
 	if (!trace_options[i])
-		ret = set_tracer_option(current_trace, cmp, neg);
+		ret = set_tracer_option(tr->current_trace, cmp, neg);
 
 	mutex_unlock(&trace_types_lock);
 
···
 tracing_trace_options_write(struct file *filp, const char __user *ubuf,
 			size_t cnt, loff_t *ppos)
 {
+	struct seq_file *m = filp->private_data;
+	struct trace_array *tr = m->private;
 	char buf[64];
 	int ret;
 
···
 
 	buf[cnt] = 0;
 
-	ret = trace_set_options(buf);
+	ret = trace_set_options(tr, buf);
 	if (ret < 0)
 		return ret;
 
···
 {
 	if (tracing_disabled)
 		return -ENODEV;
-	return single_open(file, tracing_trace_options_show, NULL);
+
+	return single_open(file, tracing_trace_options_show, inode->i_private);
 }
 
 static const struct file_operations tracing_iter_fops = {
···
 
 static const char readme_msg[] =
 	"tracing mini-HOWTO:\n\n"
-	"# mount -t debugfs nodev /sys/kernel/debug\n\n"
-	"# cat /sys/kernel/debug/tracing/available_tracers\n"
-	"wakeup wakeup_rt preemptirqsoff preemptoff irqsoff function nop\n\n"
-	"# cat /sys/kernel/debug/tracing/current_tracer\n"
-	"nop\n"
-	"# echo wakeup > /sys/kernel/debug/tracing/current_tracer\n"
-	"# cat /sys/kernel/debug/tracing/current_tracer\n"
-	"wakeup\n"
-	"# cat /sys/kernel/debug/tracing/trace_options\n"
-	"noprint-parent nosym-offset nosym-addr noverbose\n"
-	"# echo print-parent > /sys/kernel/debug/tracing/trace_options\n"
-	"# echo 1 > /sys/kernel/debug/tracing/tracing_on\n"
-	"# cat /sys/kernel/debug/tracing/trace > /tmp/trace.txt\n"
-	"# echo 0 > /sys/kernel/debug/tracing/tracing_on\n"
+	"# echo 0 > tracing_on : quick way to disable tracing\n"
+	"# echo 1 > tracing_on : quick way to re-enable tracing\n\n"
+	" Important files:\n"
+	"  trace\t\t\t- The static contents of the buffer\n"
+	"\t\t\t  To clear the buffer write into this file: echo > trace\n"
+	"  trace_pipe\t\t- A consuming read to see the contents of the buffer\n"
+	"  current_tracer\t- function and latency tracers\n"
+	"  available_tracers\t- list of configured tracers for current_tracer\n"
+	"  buffer_size_kb\t- view and modify size of per cpu buffer\n"
+	"  buffer_total_size_kb  - view total size of all cpu buffers\n\n"
+	"  trace_clock\t\t-change the clock used to order events\n"
+	"       local:   Per cpu clock but may not be synced across CPUs\n"
+	"      global:   Synced across CPUs but slows tracing down.\n"
+	"     counter:   Not a clock, but just an increment\n"
+	"      uptime:   Jiffy counter from time of boot\n"
+	"        perf:   Same clock that perf events use\n"
+#ifdef CONFIG_X86_64
+	"     x86-tsc:   TSC cycle counter\n"
+#endif
+	"\n  trace_marker\t\t- Writes into this file writes into the kernel buffer\n"
+	"  tracing_cpumask\t- Limit which CPUs to trace\n"
+	"  instances\t\t- Make sub-buffers with: mkdir instances/foo\n"
+	"\t\t\t  Remove sub-buffer with rmdir\n"
+	"  trace_options\t\t- Set format or modify how tracing happens\n"
+	"\t\t\t  Disable an option by adding a suffix 'no' to the option name\n"
+#ifdef CONFIG_DYNAMIC_FTRACE
+	"\n  available_filter_functions - list of functions that can be filtered on\n"
+	"  set_ftrace_filter\t- echo function name in here to only trace these functions\n"
+	"            accepts: func_full_name, *func_end, func_begin*, *func_middle*\n"
+	"            modules: Can select a group via module\n"
+	"             Format: :mod:<module-name>\n"
+	"             example: echo :mod:ext3 > set_ftrace_filter\n"
+	"            triggers: a command to perform when function is hit\n"
+	"              Format: <function>:<trigger>[:count]\n"
+	"             trigger: traceon, traceoff\n"
+	"                      enable_event:<system>:<event>\n"
+	"                      disable_event:<system>:<event>\n"
+#ifdef CONFIG_STACKTRACE
+	"                      stacktrace\n"
+#endif
+#ifdef CONFIG_TRACER_SNAPSHOT
+	"                      snapshot\n"
+#endif
+	"             example: echo do_fault:traceoff > set_ftrace_filter\n"
+	"                      echo do_trap:traceoff:3 > set_ftrace_filter\n"
+	"             The first one will disable tracing every time do_fault is hit\n"
+	"             The second will disable tracing at most 3 times when do_trap is hit\n"
+	"               The first time do trap is hit and it disables tracing, the counter\n"
+	"               will decrement to 2. If tracing is already disabled, the counter\n"
+	"               will not decrement. It only decrements when the trigger did work\n"
+	"             To remove trigger without count:\n"
+	"               echo '!<function>:<trigger> > set_ftrace_filter\n"
+	"             To remove trigger with a count:\n"
+	"               echo '!<function>:<trigger>:0 > set_ftrace_filter\n"
+	"  set_ftrace_notrace\t- echo function name in here to never trace.\n"
+	"            accepts: func_full_name, *func_end, func_begin*, *func_middle*\n"
+	"            modules: Can select a group via module command :mod:\n"
+	"            Does not accept triggers\n"
+#endif /* CONFIG_DYNAMIC_FTRACE */
+#ifdef CONFIG_FUNCTION_TRACER
+	"  set_ftrace_pid\t- Write pid(s) to only function trace those pids (function)\n"
+#endif
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	"  set_graph_function\t- Trace the nested calls of a function (function_graph)\n"
+	"  max_graph_depth\t- Trace a limited depth of nested calls (0 is unlimited)\n"
+#endif
+#ifdef CONFIG_TRACER_SNAPSHOT
+	"\n  snapshot\t\t- Like 'trace' but shows the content of the static snapshot buffer\n"
+	"\t\t\t  Read the contents for more information\n"
+#endif
+#ifdef CONFIG_STACKTRACE
+	"  stack_trace\t\t- Shows the max stack trace when active\n"
+	"  stack_max_size\t- Shows current max stack size that was traced\n"
+	"\t\t\t  Write into this file to reset the max size (trigger a new trace)\n"
+#ifdef CONFIG_DYNAMIC_FTRACE
+	"  stack_trace_filter\t- Like set_ftrace_filter but limits what stack_trace traces\n"
+#endif
+#endif /* CONFIG_STACKTRACE */
 ;
 
 static ssize_t
···
 tracing_set_trace_read(struct file *filp, char __user *ubuf,
 		       size_t cnt, loff_t *ppos)
 {
+	struct trace_array *tr = filp->private_data;
 	char buf[MAX_TRACER_SIZE+2];
 	int r;
 
 	mutex_lock(&trace_types_lock);
-	r = sprintf(buf, "%s\n", current_trace->name);
+	r = sprintf(buf, "%s\n", tr->current_trace->name);
 	mutex_unlock(&trace_types_lock);
 
 	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
···
 
 int tracer_init(struct tracer *t, struct trace_array *tr)
 {
-	tracing_reset_online_cpus(tr);
+	tracing_reset_online_cpus(&tr->trace_buffer);
 	return t->init(tr);
 }
 
-static void set_buffer_entries(struct trace_array *tr, unsigned long val)
+static void set_buffer_entries(struct trace_buffer *buf, unsigned long val)
 {
 	int cpu;
+
 	for_each_tracing_cpu(cpu)
-		tr->data[cpu]->entries = val;
+		per_cpu_ptr(buf->data, cpu)->entries = val;
 }
 
+#ifdef CONFIG_TRACER_MAX_TRACE
 /* resize @tr's buffer to the size of @size_tr's entries */
-static int resize_buffer_duplicate_size(struct trace_array *tr,
-					struct trace_array *size_tr, int cpu_id)
+static int resize_buffer_duplicate_size(struct trace_buffer *trace_buf,
+					struct trace_buffer *size_buf, int cpu_id)
 {
 	int cpu, ret = 0;
 
 	if (cpu_id == RING_BUFFER_ALL_CPUS) {
 		for_each_tracing_cpu(cpu) {
-			ret = ring_buffer_resize(tr->buffer,
-					size_tr->data[cpu]->entries, cpu);
+			ret = ring_buffer_resize(trace_buf->buffer,
+				 per_cpu_ptr(size_buf->data, cpu)->entries, cpu);
 			if (ret < 0)
 				break;
-			tr->data[cpu]->entries = size_tr->data[cpu]->entries;
+			per_cpu_ptr(trace_buf->data, cpu)->entries =
+				per_cpu_ptr(size_buf->data, cpu)->entries;
 		}
 	} else {
-		ret = ring_buffer_resize(tr->buffer,
-					size_tr->data[cpu_id]->entries, cpu_id);
+		ret = ring_buffer_resize(trace_buf->buffer,
+				 per_cpu_ptr(size_buf->data, cpu_id)->entries, cpu_id);
 		if (ret == 0)
-			tr->data[cpu_id]->entries =
-				size_tr->data[cpu_id]->entries;
+			per_cpu_ptr(trace_buf->data, cpu_id)->entries =
+				per_cpu_ptr(size_buf->data, cpu_id)->entries;
 	}
 
 	return ret;
 }
+#endif /* CONFIG_TRACER_MAX_TRACE */
 
-static int __tracing_resize_ring_buffer(unsigned long size, int cpu)
+static int __tracing_resize_ring_buffer(struct trace_array *tr,
+					unsigned long size, int cpu)
 {
 	int ret;
 
···
 	 * we use the size that was given, and we can forget about
 	 * expanding it later.
 	 */
-	ring_buffer_expanded = 1;
+	ring_buffer_expanded = true;
 
 	/* May be called before buffers are initialized */
-	if (!global_trace.buffer)
+	if (!tr->trace_buffer.buffer)
 		return 0;
 
-	ret = ring_buffer_resize(global_trace.buffer, size, cpu);
+	ret = ring_buffer_resize(tr->trace_buffer.buffer, size, cpu);
 	if (ret < 0)
 		return ret;
 
-	if (!current_trace->use_max_tr)
+#ifdef CONFIG_TRACER_MAX_TRACE
+	if (!(tr->flags & TRACE_ARRAY_FL_GLOBAL) ||
+	    !tr->current_trace->use_max_tr)
 		goto out;
 
-	ret = ring_buffer_resize(max_tr.buffer, size, cpu);
+	ret = ring_buffer_resize(tr->max_buffer.buffer, size, cpu);
 	if (ret < 0) {
-		int r = resize_buffer_duplicate_size(&global_trace,
-						     &global_trace, cpu);
+		int r = resize_buffer_duplicate_size(&tr->trace_buffer,
+						     &tr->trace_buffer, cpu);
 		if (r < 0) {
 			/*
 			 * AARGH! We are left with different
···
 	}
 
 	if (cpu == RING_BUFFER_ALL_CPUS)
-		set_buffer_entries(&max_tr, size);
+		set_buffer_entries(&tr->max_buffer, size);
 	else
-		max_tr.data[cpu]->entries = size;
+		per_cpu_ptr(tr->max_buffer.data, cpu)->entries = size;
 
  out:
+#endif /* CONFIG_TRACER_MAX_TRACE */
+
 	if (cpu == RING_BUFFER_ALL_CPUS)
-		set_buffer_entries(&global_trace, size);
+		set_buffer_entries(&tr->trace_buffer, size);
 	else
-		global_trace.data[cpu]->entries = size;
+		per_cpu_ptr(tr->trace_buffer.data, cpu)->entries = size;
 
 	return ret;
 }
 
-static ssize_t tracing_resize_ring_buffer(unsigned long size, int cpu_id)
+static ssize_t tracing_resize_ring_buffer(struct trace_array *tr,
+					  unsigned long size, int cpu_id)
 {
 	int ret = size;
 
···
 		}
 	}
 
-	ret = __tracing_resize_ring_buffer(size, cpu_id);
+	ret = __tracing_resize_ring_buffer(tr, size, cpu_id);
 	if (ret < 0)
 		ret = -ENOMEM;
 
···
 
 	mutex_lock(&trace_types_lock);
 	if (!ring_buffer_expanded)
-		ret = __tracing_resize_ring_buffer(trace_buf_size,
+		ret = __tracing_resize_ring_buffer(&global_trace, trace_buf_size,
 						RING_BUFFER_ALL_CPUS);
 	mutex_unlock(&trace_types_lock);
 
···
 struct trace_option_dentry;
 
 static struct trace_option_dentry *
-create_trace_option_files(struct tracer *tracer);
+create_trace_option_files(struct trace_array *tr, struct tracer *tracer);
 
 static void
 destroy_trace_option_files(struct trace_option_dentry *topts);
···
 	static struct trace_option_dentry *topts;
 	struct trace_array *tr = &global_trace;
 	struct tracer *t;
+#ifdef CONFIG_TRACER_MAX_TRACE
 	bool had_max_tr;
+#endif
 	int ret = 0;
 
 	mutex_lock(&trace_types_lock);
 
 	if (!ring_buffer_expanded) {
-		ret = __tracing_resize_ring_buffer(trace_buf_size,
+		ret = __tracing_resize_ring_buffer(tr, trace_buf_size,
 						RING_BUFFER_ALL_CPUS);
 		if (ret < 0)
 			goto out;
···
 		ret = -EINVAL;
 		goto out;
 	}
-	if (t == current_trace)
+	if (t == tr->current_trace)
 		goto out;
 
 	trace_branch_disable();
 
-	current_trace->enabled = false;
+	tr->current_trace->enabled = false;
 
-	if (current_trace->reset)
-		current_trace->reset(tr);
+	if (tr->current_trace->reset)
+		tr->current_trace->reset(tr);
 
-	had_max_tr = current_trace->allocated_snapshot;
-	current_trace = &nop_trace;
+	/* Current trace needs to be nop_trace before synchronize_sched */
+	tr->current_trace = &nop_trace;
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+	had_max_tr = tr->allocated_snapshot;
 
 	if (had_max_tr && !t->use_max_tr) {
 		/*
···
 		 * so a synchronized_sched() is sufficient.
 		 */
 		synchronize_sched();
-		/*
-		 * We don't free the ring buffer. instead, resize it because
-		 * The max_tr ring buffer has some state (e.g. ring->clock) and
-		 * we want preserve it.
-		 */
-		ring_buffer_resize(max_tr.buffer, 1, RING_BUFFER_ALL_CPUS);
-		set_buffer_entries(&max_tr, 1);
-		tracing_reset_online_cpus(&max_tr);
-		current_trace->allocated_snapshot = false;
+		free_snapshot(tr);
 	}
+#endif
 	destroy_trace_option_files(topts);
 
-	topts = create_trace_option_files(t);
+	topts = create_trace_option_files(tr, t);
+
+#ifdef CONFIG_TRACER_MAX_TRACE
 	if (t->use_max_tr && !had_max_tr) {
-		/* we need to make per cpu buffer sizes equivalent */
-		ret = resize_buffer_duplicate_size(&max_tr, &global_trace,
-						   RING_BUFFER_ALL_CPUS);
+		ret = alloc_snapshot(tr);
 		if (ret < 0)
 			goto out;
-		t->allocated_snapshot = true;
 	}
+#endif
 
 	if (t->init) {
 		ret = tracer_init(t, tr);
···
 			goto out;
 	}
 
-	current_trace = t;
-	current_trace->enabled = true;
+	tr->current_trace = t;
+	tr->current_trace->enabled = true;
 	trace_branch_enable(tr);
  out:
 	mutex_unlock(&trace_types_lock);
···
 
 static int tracing_open_pipe(struct inode *inode, struct file *filp)
 {
-	long cpu_file = (long) inode->i_private;
+	struct trace_cpu *tc = inode->i_private;
+	struct trace_array *tr = tc->tr;
 	struct trace_iterator *iter;
 	int ret = 0;
 
···
 		ret = -ENOMEM;
 		goto fail;
 	}
-	*iter->trace = *current_trace;
+	*iter->trace = *tr->current_trace;
 
 	if (!alloc_cpumask_var(&iter->started, GFP_KERNEL)) {
 		ret = -ENOMEM;
···
 	if (trace_clocks[trace_clock_id].in_ns)
 		iter->iter_flags |= TRACE_FILE_TIME_IN_NS;
 
-	iter->cpu_file = cpu_file;
-	iter->tr = &global_trace;
+	iter->cpu_file = tc->cpu;
+	iter->tr = tc->tr;
+	iter->trace_buffer = &tc->tr->trace_buffer;
 	mutex_init(&iter->mutex);
 	filp->private_data = iter;
 
···
 }
 
 static unsigned int
-tracing_poll_pipe(struct file *filp, poll_table *poll_table)
+trace_poll(struct trace_iterator *iter, struct file *filp, poll_table *poll_table)
 {
-	struct trace_iterator *iter = filp->private_data;
+	/* Iterators are static, they should be filled or empty */
+	if (trace_buffer_iter(iter, iter->cpu_file))
+		return POLLIN | POLLRDNORM;
 
-	if (trace_flags & TRACE_ITER_BLOCK) {
+	if (trace_flags & TRACE_ITER_BLOCK)
 		/*
 		 * Always select as readable when in blocking mode
 		 */
 		return POLLIN | POLLRDNORM;
-	} else {
-		if (!trace_empty(iter))
-			return POLLIN | POLLRDNORM;
-		poll_wait(filp, &trace_wait, poll_table);
-		if (!trace_empty(iter))
-			return POLLIN | POLLRDNORM;
+	else
+		return ring_buffer_poll_wait(iter->trace_buffer->buffer, iter->cpu_file,
+					     filp, poll_table);
+}
 
-		return 0;
-	}
+static unsigned int
+tracing_poll_pipe(struct file *filp, poll_table *poll_table)
+{
+	struct trace_iterator *iter = filp->private_data;
+
+	return trace_poll(iter, filp, poll_table);
 }
 
 /*
···
 		  size_t cnt, loff_t *ppos)
 {
 	struct trace_iterator *iter = filp->private_data;
+	struct trace_array *tr = iter->tr;
 	ssize_t sret;
 
 	/* return any leftover data */
···
 
 	/* copy the tracer to avoid using a global lock all around */
 	mutex_lock(&trace_types_lock);
-	if (unlikely(iter->trace->name != current_trace->name))
-		*iter->trace = *current_trace;
+	if (unlikely(iter->trace->name != tr->current_trace->name))
+		*iter->trace = *tr->current_trace;
 	mutex_unlock(&trace_types_lock);
 
 	/*
···
 		.ops		= &tracing_pipe_buf_ops,
 		.spd_release	= tracing_spd_release_pipe,
 	};
+	struct trace_array *tr = iter->tr;
 	ssize_t ret;
 	size_t rem;
 	unsigned int i;
···
 
 	/* copy the tracer to avoid using a global lock all around */
 	mutex_lock(&trace_types_lock);
-	if (unlikely(iter->trace->name != current_trace->name))
-		*iter->trace = *current_trace;
+	if (unlikely(iter->trace->name != tr->current_trace->name))
+		*iter->trace = *tr->current_trace;
 	mutex_unlock(&trace_types_lock);
 
 	mutex_lock(&iter->mutex);
···
 	goto out;
 }
 
-struct ftrace_entries_info {
-	struct trace_array	*tr;
-	int			cpu;
-};
-
-static int tracing_entries_open(struct inode *inode, struct file *filp)
-{
-	struct ftrace_entries_info *info;
-
-	if (tracing_disabled)
-		return -ENODEV;
-
-	info = kzalloc(sizeof(*info), GFP_KERNEL);
-	if (!info)
-		return -ENOMEM;
-
-	info->tr = &global_trace;
-	info->cpu = (unsigned long)inode->i_private;
-
-	filp->private_data = info;
-
-	return 0;
-}
-
 static ssize_t
 tracing_entries_read(struct file *filp, char __user *ubuf,
 		     size_t cnt, loff_t *ppos)
 {
-	struct ftrace_entries_info *info = filp->private_data;
-	struct trace_array *tr = info->tr;
+	struct trace_cpu *tc = filp->private_data;
+	struct trace_array *tr = tc->tr;
 	char buf[64];
 	int r = 0;
 	ssize_t ret;
 
 	mutex_lock(&trace_types_lock);
 
-	if (info->cpu == RING_BUFFER_ALL_CPUS) {
+	if (tc->cpu == RING_BUFFER_ALL_CPUS) {
 		int cpu, buf_size_same;
 		unsigned long size;
 
···
 		for_each_tracing_cpu(cpu) {
 			/* fill in the size from first enabled cpu */
 			if (size == 0)
-				size = tr->data[cpu]->entries;
-			if (size != tr->data[cpu]->entries) {
+				size = per_cpu_ptr(tr->trace_buffer.data, cpu)->entries;
+			if (size != per_cpu_ptr(tr->trace_buffer.data, cpu)->entries) {
 				buf_size_same = 0;
 				break;
 			}
···
 		} else
 			r = sprintf(buf, "X\n");
 	} else
-		r = sprintf(buf, "%lu\n", tr->data[info->cpu]->entries >> 10);
+		r = sprintf(buf, "%lu\n", per_cpu_ptr(tr->trace_buffer.data, tc->cpu)->entries >> 10);
 
 	mutex_unlock(&trace_types_lock);
 
···
 tracing_entries_write(struct file *filp, const char __user *ubuf,
 		      size_t cnt, loff_t *ppos)
 {
-	struct ftrace_entries_info *info = filp->private_data;
+	struct trace_cpu *tc = filp->private_data;
 	unsigned long val;
 	int ret;
 
···
 	/* value is in KB */
 	val <<= 10;
 
-	ret = tracing_resize_ring_buffer(val, info->cpu);
+	ret = tracing_resize_ring_buffer(tc->tr, val, tc->cpu);
 	if (ret < 0)
 		return ret;
 
 	*ppos += cnt;
 
 	return cnt;
-}
-
-static int
-tracing_entries_release(struct inode *inode, struct file *filp)
-{
-	struct ftrace_entries_info *info = filp->private_data;
-
-	kfree(info);
-
-	return 0;
 }
 
 static ssize_t
···
 
 	mutex_lock(&trace_types_lock);
 	for_each_tracing_cpu(cpu) {
-		size += tr->data[cpu]->entries >> 10;
+		size += per_cpu_ptr(tr->trace_buffer.data, cpu)->entries >> 10;
 		if (!ring_buffer_expanded)
 			expanded_size += trace_buf_size >> 10;
 	}
···
 static int
 tracing_free_buffer_release(struct inode *inode, struct file *filp)
 {
+	struct trace_array *tr = inode->i_private;
+
 	/* disable tracing ? */
 	if (trace_flags & TRACE_ITER_STOP_ON_FREE)
 		tracing_off();
 	/* resize the ring buffer to 0 */
-	tracing_resize_ring_buffer(0, RING_BUFFER_ALL_CPUS);
+	tracing_resize_ring_buffer(tr, 0, RING_BUFFER_ALL_CPUS);
 
 	return 0;
 }
···
 
 	local_save_flags(irq_flags);
 	size = sizeof(*entry) + cnt + 2; /* possible \n added */
-	buffer = global_trace.buffer;
+	buffer = global_trace.trace_buffer.buffer;
 	event = trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
 					  irq_flags, preempt_count());
 	if (!event) {
···
 
 static int tracing_clock_show(struct seq_file *m, void *v)
 {
+	struct trace_array *tr = m->private;
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(trace_clocks); i++)
 		seq_printf(m,
 			"%s%s%s%s", i ? " " : "",
-			i == trace_clock_id ? "[" : "", trace_clocks[i].name,
-			i == trace_clock_id ? "]" : "");
+			i == tr->clock_id ? "[" : "", trace_clocks[i].name,
+			i == tr->clock_id ? "]" : "");
 	seq_putc(m, '\n');
 
 	return 0;
···
 static ssize_t tracing_clock_write(struct file *filp, const char __user *ubuf,
 				   size_t cnt, loff_t *fpos)
 {
+	struct seq_file *m = filp->private_data;
+	struct trace_array *tr = m->private;
 	char buf[64];
 	const char *clockstr;
 	int i;
···
 	if (i == ARRAY_SIZE(trace_clocks))
 		return -EINVAL;
 
-	trace_clock_id = i;
-
 	mutex_lock(&trace_types_lock);
 
-	ring_buffer_set_clock(global_trace.buffer, trace_clocks[i].func);
-	if (max_tr.buffer)
-		ring_buffer_set_clock(max_tr.buffer, trace_clocks[i].func);
+	tr->clock_id = i;
+
+	ring_buffer_set_clock(tr->trace_buffer.buffer, trace_clocks[i].func);
 
 	/*
 	 * New clock may not be consistent with the previous clock.
 	 * Reset the buffer so that it doesn't have incomparable timestamps.
 	 */
-	tracing_reset_online_cpus(&global_trace);
-	tracing_reset_online_cpus(&max_tr);
+	tracing_reset_online_cpus(&global_trace.trace_buffer);
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+	if (tr->flags & TRACE_ARRAY_FL_GLOBAL && tr->max_buffer.buffer)
+		ring_buffer_set_clock(tr->max_buffer.buffer, trace_clocks[i].func);
+	tracing_reset_online_cpus(&global_trace.max_buffer);
+#endif
 
 	mutex_unlock(&trace_types_lock);
 
···
 {
 	if (tracing_disabled)
 		return -ENODEV;
-	return single_open(file, tracing_clock_show, NULL);
+
+	return single_open(file, tracing_clock_show, inode->i_private);
 }
+
+struct ftrace_buffer_info {
+	struct trace_iterator	iter;
+	void			*spare;
+	unsigned int		read;
+};
 
 #ifdef CONFIG_TRACER_SNAPSHOT
 static int tracing_snapshot_open(struct inode *inode, struct file *file)
 {
+	struct trace_cpu *tc = inode->i_private;
 	struct trace_iterator *iter;
+	struct seq_file *m;
 	int ret = 0;
 
 	if (file->f_mode & FMODE_READ) {
 		iter = __tracing_open(inode, file, true);
 		if (IS_ERR(iter))
 			ret = PTR_ERR(iter);
+	} else {
+		/* Writes still need the seq_file to hold the private data */
+		m = kzalloc(sizeof(*m), GFP_KERNEL);
+		if (!m)
+			return -ENOMEM;
+		iter = kzalloc(sizeof(*iter), GFP_KERNEL);
+		if (!iter) {
+			kfree(m);
+			return -ENOMEM;
+		}
+		iter->tr = tc->tr;
+		iter->trace_buffer = &tc->tr->max_buffer;
+		iter->cpu_file = tc->cpu;
+		m->private = iter;
+		file->private_data = m;
 	}
+
 	return ret;
 }
 
···
 tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt,
 		       loff_t *ppos)
 {
+	struct seq_file *m = filp->private_data;
+	struct trace_iterator *iter = m->private;
+	struct trace_array *tr = iter->tr;
 	unsigned long val;
 	int ret;
 
···
 
 	mutex_lock(&trace_types_lock);
 
-	if (current_trace->use_max_tr) {
+	if (tr->current_trace->use_max_tr) {
 		ret = -EBUSY;
 		goto out;
 	}
 
 	switch (val) {
 	case 0:
-		if (current_trace->allocated_snapshot) {
-			/* free spare buffer */
-			ring_buffer_resize(max_tr.buffer, 1,
-					   RING_BUFFER_ALL_CPUS);
-			set_buffer_entries(&max_tr, 1);
-			tracing_reset_online_cpus(&max_tr);
-			current_trace->allocated_snapshot = false;
+		if (iter->cpu_file != RING_BUFFER_ALL_CPUS) {
+			ret = -EINVAL;
+			break;
 		}
+		if (tr->allocated_snapshot)
+			free_snapshot(tr);
 		break;
 	case 1:
-		if (!current_trace->allocated_snapshot) {
-			/* allocate spare buffer */
-			ret = resize_buffer_duplicate_size(&max_tr,
-					&global_trace, RING_BUFFER_ALL_CPUS);
+/* Only allow per-cpu swap if the ring buffer supports it */
+#ifndef CONFIG_RING_BUFFER_ALLOW_SWAP
+		if (iter->cpu_file != RING_BUFFER_ALL_CPUS) {
+			ret = -EINVAL;
+			break;
+		}
+#endif
+		if (!tr->allocated_snapshot) {
+			ret = alloc_snapshot(tr);
 			if (ret < 0)
 				break;
-			current_trace->allocated_snapshot = true;
 		}
-
 		local_irq_disable();
 		/* Now, we're going to swap */
-		update_max_tr(&global_trace, current, smp_processor_id());
+		if (iter->cpu_file == RING_BUFFER_ALL_CPUS)
+			update_max_tr(tr, current, smp_processor_id());
+		else
+			update_max_tr_single(tr, current, iter->cpu_file);
 		local_irq_enable();
 		break;
 	default:
-		if (current_trace->allocated_snapshot)
-			tracing_reset_online_cpus(&max_tr);
+		if (tr->allocated_snapshot) {
+			if (iter->cpu_file == RING_BUFFER_ALL_CPUS)
+				tracing_reset_online_cpus(&tr->max_buffer);
+			else
+				tracing_reset(&tr->max_buffer, iter->cpu_file);
+		}
 		break;
 	}
 
···
 	mutex_unlock(&trace_types_lock);
 	return ret;
 }
+
+static int tracing_snapshot_release(struct inode *inode, struct file *file)
+{
+	struct seq_file *m = file->private_data;
+
+	if (file->f_mode & FMODE_READ)
+		return tracing_release(inode, file);
+
+	/* If write only, the seq_file is just a stub */
+	if (m)
+		kfree(m->private);
+	kfree(m);
+
+	return 0;
+}
+
+static int tracing_buffers_open(struct inode *inode, struct file *filp);
+static ssize_t tracing_buffers_read(struct file *filp, char __user *ubuf,
+				    size_t count, loff_t *ppos);
+static int tracing_buffers_release(struct inode *inode, struct file *file);
+static ssize_t tracing_buffers_splice_read(struct file *file, loff_t *ppos,
+		   struct pipe_inode_info *pipe, size_t len, unsigned int flags);
+
+static int snapshot_raw_open(struct inode *inode, struct file *filp)
+{
+	struct ftrace_buffer_info *info;
+	int ret;
+
+	ret = tracing_buffers_open(inode, filp);
+	if (ret < 0)
+		return ret;
+
+	info = filp->private_data;
+
+	if (info->iter.trace->use_max_tr) {
+		tracing_buffers_release(inode, filp);
+		return -EBUSY;
+	}
+
+	info->iter.snapshot = true;
+	info->iter.trace_buffer = &info->iter.tr->max_buffer;
+
+	return ret;
+}
+
 #endif /* CONFIG_TRACER_SNAPSHOT */
 
 
···
 };
 
 static const struct file_operations tracing_entries_fops = {
-	.open		= tracing_entries_open,
+	.open		= tracing_open_generic,
 	.read		= tracing_entries_read,
 	.write		= tracing_entries_write,
-	.release	= tracing_entries_release,
 	.llseek		= generic_file_llseek,
 };
 
···
 	.read		= seq_read,
 	.write		= tracing_snapshot_write,
 	.llseek		= tracing_seek,
-	.release	= tracing_release,
+	.release	= tracing_snapshot_release,
 };
-#endif /* CONFIG_TRACER_SNAPSHOT */
 
-struct ftrace_buffer_info {
-	struct trace_array	*tr;
-	void			*spare;
-	int			cpu;
-	unsigned int		read;
+static const struct file_operations snapshot_raw_fops = {
+	.open		= snapshot_raw_open,
+	.read		= tracing_buffers_read,
+	.release	= tracing_buffers_release,
+	.splice_read	= tracing_buffers_splice_read,
+	.llseek		= no_llseek,
 };
+
+#endif /* CONFIG_TRACER_SNAPSHOT */
 
 static int tracing_buffers_open(struct inode *inode, struct file *filp)
 {
-	int cpu = (int)(long)inode->i_private;
+	struct trace_cpu *tc = inode->i_private;
+	struct trace_array *tr = tc->tr;
 	struct ftrace_buffer_info *info;
 
 	if (tracing_disabled)
···
 	if (!info)
 		return -ENOMEM;
 
-	info->tr	= &global_trace;
-	info->cpu	= cpu;
-	info->spare	= NULL;
+	mutex_lock(&trace_types_lock);
+
+	tr->ref++;
+
+	info->iter.tr		= tr;
+	info->iter.cpu_file	= tc->cpu;
+	info->iter.trace	= tr->current_trace;
+	info->iter.trace_buffer = &tr->trace_buffer;
+	info->spare		= NULL;
 	/* Force reading ring buffer for first read */
-	info->read	= (unsigned int)-1;
+	info->read		= (unsigned int)-1;
 
 	filp->private_data = info;
 
+	mutex_unlock(&trace_types_lock);
+
 	return nonseekable_open(inode, filp);
+}
+
+static unsigned int
+tracing_buffers_poll(struct file *filp, poll_table *poll_table)
+{
+	struct ftrace_buffer_info *info = filp->private_data;
+	struct trace_iterator *iter = &info->iter;
+
+	return trace_poll(iter, filp, poll_table);
 }
 
 static ssize_t
···
 		     size_t count, loff_t *ppos)
 {
 	struct ftrace_buffer_info *info = filp->private_data;
+	struct trace_iterator *iter = &info->iter;
 	ssize_t ret;
-	size_t size;
+	ssize_t size;
 
 	if (!count)
 		return 0;
 
+	mutex_lock(&trace_types_lock);
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+	if (iter->snapshot && iter->tr->current_trace->use_max_tr) {
+		size = -EBUSY;
+		goto out_unlock;
+	}
+#endif
+
 	if (!info->spare)
-		info->spare = ring_buffer_alloc_read_page(info->tr->buffer, info->cpu);
+		info->spare = ring_buffer_alloc_read_page(iter->trace_buffer->buffer,
+							  iter->cpu_file);
+	size = -ENOMEM;
 	if (!info->spare)
-		return -ENOMEM;
+		goto out_unlock;
 
 	/* Do we have previous read data to read? */
 	if (info->read < PAGE_SIZE)
 		goto read;
 
-	trace_access_lock(info->cpu);
-	ret = ring_buffer_read_page(info->tr->buffer,
+ again:
+	trace_access_lock(iter->cpu_file);
+	ret = ring_buffer_read_page(iter->trace_buffer->buffer,
 				    &info->spare,
 				    count,
-				    info->cpu, 0);
-	trace_access_unlock(info->cpu);
-	if (ret < 0)
-		return 0;
+				    iter->cpu_file, 0);
+	trace_access_unlock(iter->cpu_file);
+
+	if (ret < 0) {
+		if (trace_empty(iter)) {
+			if ((filp->f_flags & O_NONBLOCK)) {
+				size = -EAGAIN;
+				goto out_unlock;
+			}
+			mutex_unlock(&trace_types_lock);
+			iter->trace->wait_pipe(iter);
+			mutex_lock(&trace_types_lock);
+			if (signal_pending(current)) {
+				size = -EINTR;
+				goto out_unlock;
+			}
+			goto again;
+		}
+		size = 0;
+		goto out_unlock;
+	}
 
 	info->read = 0;
-
-read:
+ read:
 	size = PAGE_SIZE - info->read;
 	if (size > count)
 		size = count;
 
 	ret = copy_to_user(ubuf, info->spare + info->read, size);
-	if (ret == size)
-		return -EFAULT;
+	if (ret == size) {
+		size = -EFAULT;
+		goto out_unlock;
+	}
 	size -= ret;
 
 	*ppos += size;
 	info->read += size;
+
+ out_unlock:
+	mutex_unlock(&trace_types_lock);
 
 	return size;
 }
···
 static int tracing_buffers_release(struct inode *inode, struct file *file)
 {
 	struct ftrace_buffer_info *info = file->private_data;
+	struct trace_iterator *iter = &info->iter;
+
+	mutex_lock(&trace_types_lock);
+
+	WARN_ON(!iter->tr->ref);
+	iter->tr->ref--;
 
 	if (info->spare)
-		ring_buffer_free_read_page(info->tr->buffer, info->spare);
+		ring_buffer_free_read_page(iter->trace_buffer->buffer, info->spare);
 	kfree(info);
+
+	mutex_unlock(&trace_types_lock);
 
 	return 0;
 }
···
 			    unsigned int flags)
 {
 	struct ftrace_buffer_info *info = file->private_data;
+	struct trace_iterator *iter = &info->iter;
 	struct partial_page partial_def[PIPE_DEF_BUFFERS];
 	struct page *pages_def[PIPE_DEF_BUFFERS];
 	struct splice_pipe_desc spd = {
···
 	};
 	struct buffer_ref *ref;
 	int entries, size, i;
-	size_t ret;
+	ssize_t ret;
 
-	if (splice_grow_spd(pipe, &spd))
-		return -ENOMEM;
+	mutex_lock(&trace_types_lock);
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+	if (iter->snapshot && iter->tr->current_trace->use_max_tr) {
+		ret = -EBUSY;
+		goto out;
+	}
+#endif
+
+	if (splice_grow_spd(pipe, &spd)) {
+		ret = -ENOMEM;
+		goto out;
+	}
 
 	if (*ppos & (PAGE_SIZE - 1)) {
 		ret = -EINVAL;
···
 		len &= PAGE_MASK;
 	}
 
-	trace_access_lock(info->cpu);
-	entries = ring_buffer_entries_cpu(info->tr->buffer, info->cpu);
+ again:
+	trace_access_lock(iter->cpu_file);
+	entries = ring_buffer_entries_cpu(iter->trace_buffer->buffer, iter->cpu_file);
 
 	for (i = 0; i < pipe->buffers && len && entries; i++, len -= PAGE_SIZE) {
 		struct page *page;
···
 			break;
 
 		ref->ref = 1;
-		ref->buffer = info->tr->buffer;
-		ref->page = ring_buffer_alloc_read_page(ref->buffer, info->cpu);
+		ref->buffer = iter->trace_buffer->buffer;
+		ref->page = ring_buffer_alloc_read_page(ref->buffer, iter->cpu_file);
 		if (!ref->page) {
 			kfree(ref);
 			break;
 		}
 
 		r = ring_buffer_read_page(ref->buffer, &ref->page,
-					  len, info->cpu, 1);
+					  len, iter->cpu_file, 1);
 		if (r < 0) {
 			ring_buffer_free_read_page(ref->buffer, ref->page);
 			kfree(ref);
···
 		spd.nr_pages++;
 		*ppos += PAGE_SIZE;
 
-		entries = ring_buffer_entries_cpu(info->tr->buffer, info->cpu);
+		entries = ring_buffer_entries_cpu(iter->trace_buffer->buffer, iter->cpu_file);
 	}
 
-	trace_access_unlock(info->cpu);
+	trace_access_unlock(iter->cpu_file);
 	spd.nr_pages = i;
 
 	/* did we read anything? */
 	if (!spd.nr_pages) {
-		if (flags & SPLICE_F_NONBLOCK)
+		if ((file->f_flags & O_NONBLOCK) || (flags & SPLICE_F_NONBLOCK)) {
 			ret = -EAGAIN;
-		else
-			ret = 0;
-		/* TODO: block */
-		goto out;
+			goto out;
+		}
+		mutex_unlock(&trace_types_lock);
+		iter->trace->wait_pipe(iter);
+		mutex_lock(&trace_types_lock);
+		if (signal_pending(current)) {
+			ret = -EINTR;
+			goto out;
+		}
+		goto again;
 	}
 
 	ret = splice_to_pipe(pipe, &spd);
 	splice_shrink_spd(&spd);
 out:
+	mutex_unlock(&trace_types_lock);
+
 	return ret;
 }
 
 static const struct file_operations tracing_buffers_fops = {
 	.open		= tracing_buffers_open,
 	.read		= tracing_buffers_read,
+	.poll		= tracing_buffers_poll,
 	.release	= tracing_buffers_release,
 	.splice_read	= tracing_buffers_splice_read,
 	.llseek		= no_llseek,
···
 tracing_stats_read(struct file *filp, char __user *ubuf,
 		   size_t count, loff_t *ppos)
 {
-	unsigned long cpu = (unsigned long)filp->private_data;
-	struct trace_array *tr = &global_trace;
+	struct trace_cpu *tc = filp->private_data;
+	struct trace_array *tr = tc->tr;
+	struct trace_buffer *trace_buf = &tr->trace_buffer;
 	struct trace_seq *s;
 	unsigned long cnt;
 	unsigned long long t;
 	unsigned long usec_rem;
+	int cpu = tc->cpu;
 
 	s = kmalloc(sizeof(*s), GFP_KERNEL);
 	if (!s)
···
 
 	trace_seq_init(s);
 
-	cnt = ring_buffer_entries_cpu(tr->buffer, cpu);
+	cnt = ring_buffer_entries_cpu(trace_buf->buffer, cpu);
 	trace_seq_printf(s, "entries: %ld\n", cnt);
 
-	cnt = ring_buffer_overrun_cpu(tr->buffer, cpu);
+	cnt = ring_buffer_overrun_cpu(trace_buf->buffer, cpu);
 	trace_seq_printf(s, "overrun: %ld\n", cnt);
 
-	cnt = ring_buffer_commit_overrun_cpu(tr->buffer, cpu);
+	cnt = ring_buffer_commit_overrun_cpu(trace_buf->buffer, cpu);
 	trace_seq_printf(s, "commit overrun: %ld\n", cnt);
 
-	cnt = ring_buffer_bytes_cpu(tr->buffer, cpu);
+	cnt = ring_buffer_bytes_cpu(trace_buf->buffer, cpu);
 	trace_seq_printf(s, "bytes: %ld\n", cnt);
 
 	if (trace_clocks[trace_clock_id].in_ns) {
 		/* local or global for trace_clock */
-		t = ns2usecs(ring_buffer_oldest_event_ts(tr->buffer, cpu));
+		t = ns2usecs(ring_buffer_oldest_event_ts(trace_buf->buffer, cpu));
 		usec_rem = do_div(t, USEC_PER_SEC);
 		trace_seq_printf(s, "oldest event ts: %5llu.%06lu\n",
 								t, usec_rem);
 
-		t = ns2usecs(ring_buffer_time_stamp(tr->buffer, cpu));
+		t = ns2usecs(ring_buffer_time_stamp(trace_buf->buffer, cpu));
 		usec_rem = do_div(t, USEC_PER_SEC);
 		trace_seq_printf(s, "now ts: %5llu.%06lu\n", t, usec_rem);
 	} else {
 		/* counter or tsc mode for trace_clock */
 		trace_seq_printf(s, "oldest event ts: %llu\n",
-				ring_buffer_oldest_event_ts(tr->buffer, cpu));
+				ring_buffer_oldest_event_ts(trace_buf->buffer, cpu));
 
 		trace_seq_printf(s, "now ts: %llu\n",
-				ring_buffer_time_stamp(tr->buffer, cpu));
+				ring_buffer_time_stamp(trace_buf->buffer, cpu));
 	}
 
-	cnt = ring_buffer_dropped_events_cpu(tr->buffer, cpu);
+	cnt = ring_buffer_dropped_events_cpu(trace_buf->buffer, cpu);
 	trace_seq_printf(s, "dropped events: %ld\n", cnt);
 
-	cnt = ring_buffer_read_events_cpu(tr->buffer, cpu);
+	cnt = ring_buffer_read_events_cpu(trace_buf->buffer, cpu);
 	trace_seq_printf(s, "read events: %ld\n", cnt);
 
 	count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);
···
 	.read		= tracing_read_dyn_info,
 	.llseek		= generic_file_llseek,
 };
-#endif
+#endif /* CONFIG_DYNAMIC_FTRACE */
 
-static struct dentry *d_tracer;
-
-struct dentry *tracing_init_dentry(void)
+#if defined(CONFIG_TRACER_SNAPSHOT) && defined(CONFIG_DYNAMIC_FTRACE)
+static void
+ftrace_snapshot(unsigned long ip, unsigned long parent_ip, void **data)
 {
-	static int once;
+	tracing_snapshot();
+}
 
-	if (d_tracer)
-		return d_tracer;
+static void
+ftrace_count_snapshot(unsigned long ip, unsigned long parent_ip, void **data)
+{
+	unsigned long *count = (long *)data;
+
+	if (!*count)
+		return;
+
+	if (*count != -1)
+		(*count)--;
+
+	tracing_snapshot();
+}
+
+static int
+ftrace_snapshot_print(struct seq_file *m, unsigned long ip,
+		      struct ftrace_probe_ops *ops, void *data)
+{
+	long count = (long)data;
+
+	seq_printf(m, "%ps:", (void *)ip);
+
+	seq_printf(m, "snapshot");
+
+	if (count == -1)
+		seq_printf(m, ":unlimited\n");
+	else
+		seq_printf(m, ":count=%ld\n", count);
+
+	return 0;
+}
+
+static struct ftrace_probe_ops snapshot_probe_ops = {
+	.func			= ftrace_snapshot,
+	.print			= ftrace_snapshot_print,
+};
+
+static struct ftrace_probe_ops snapshot_count_probe_ops = {
+	.func			= ftrace_count_snapshot,
+	.print			= ftrace_snapshot_print,
+};
+
+static int
+ftrace_trace_snapshot_callback(struct ftrace_hash *hash,
+			       char *glob, char *cmd, char *param, int enable)
+{
+	struct ftrace_probe_ops *ops;
+	void *count = (void *)-1;
+	char *number;
+	int ret;
+
+	/* hash funcs only work with set_ftrace_filter */
+	if (!enable)
+		return -EINVAL;
+
+	ops = param ? &snapshot_count_probe_ops :  &snapshot_probe_ops;
+
+	if (glob[0] == '!') {
+		unregister_ftrace_function_probe_func(glob+1, ops);
+		return 0;
+	}
+
+	if (!param)
+		goto out_reg;
+
+	number = strsep(&param, ":");
+
+	if (!strlen(number))
+		goto out_reg;
+
+	/*
+	 * We use the callback data field (which is a pointer)
+	 * as our counter.
+	 */
+	ret = kstrtoul(number, 0, (unsigned long *)&count);
+	if (ret)
+		return ret;
+
+ out_reg:
+	ret = register_ftrace_function_probe(glob, ops, count);
+
+	if (ret >= 0)
+		alloc_snapshot(&global_trace);
+
+	return ret < 0 ? ret : 0;
+}
+
+static struct ftrace_func_command ftrace_snapshot_cmd = {
+	.name			= "snapshot",
+	.func			= ftrace_trace_snapshot_callback,
+};
+
+static int register_snapshot_cmd(void)
+{
+	return register_ftrace_command(&ftrace_snapshot_cmd);
+}
+#else
+static inline int register_snapshot_cmd(void) { return 0; }
+#endif /* defined(CONFIG_TRACER_SNAPSHOT) && defined(CONFIG_DYNAMIC_FTRACE) */
+
+struct dentry *tracing_init_dentry_tr(struct trace_array *tr)
+{
+	if (tr->dir)
+		return tr->dir;
 
 	if (!debugfs_initialized())
 		return NULL;
 
-	d_tracer = debugfs_create_dir("tracing", NULL);
+	if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
+		tr->dir = debugfs_create_dir("tracing", NULL);
 
-	if (!d_tracer && !once) {
-		once = 1;
-		pr_warning("Could not create debugfs directory 'tracing'\n");
-		return NULL;
-	}
+	if (!tr->dir)
+		pr_warn_once("Could not create debugfs directory 'tracing'\n");
 
-	return d_tracer;
+	return tr->dir;
 }
 
-static struct dentry *d_percpu;
-
-static struct dentry *tracing_dentry_percpu(void)
+struct dentry *tracing_init_dentry(void)
 {
-	static int once;
+	return tracing_init_dentry_tr(&global_trace);
+}
+
+static struct dentry *tracing_dentry_percpu(struct trace_array *tr, int cpu)
+{
 	struct dentry *d_tracer;
 
-	if (d_percpu)
-		return d_percpu;
+	if (tr->percpu_dir)
+		return tr->percpu_dir;
 
-	d_tracer = tracing_init_dentry();
-
+	d_tracer = tracing_init_dentry_tr(tr);
 	if (!d_tracer)
 		return NULL;
 
-	d_percpu = debugfs_create_dir("per_cpu", d_tracer);
+	tr->percpu_dir = debugfs_create_dir("per_cpu", d_tracer);
 
-	if (!d_percpu && !once) {
-		once = 1;
-		pr_warning("Could not create debugfs directory 'per_cpu'\n");
-		return NULL;
-	}
+	WARN_ONCE(!tr->percpu_dir,
+		  "Could not create debugfs directory 'per_cpu/%d'\n", cpu);
 
-	return d_percpu;
+	return tr->percpu_dir;
 }
 
-static void tracing_init_debugfs_percpu(long cpu)
+static void
+tracing_init_debugfs_percpu(struct trace_array *tr, long cpu)
 {
-	struct dentry *d_percpu = tracing_dentry_percpu();
+	struct trace_array_cpu *data = per_cpu_ptr(tr->trace_buffer.data, cpu);
+	struct dentry *d_percpu = tracing_dentry_percpu(tr, cpu);
 	struct dentry *d_cpu;
 	char cpu_dir[30]; /* 30 characters should be more than enough */
 
···
 
 	/* per cpu trace_pipe */
 	trace_create_file("trace_pipe", 0444, d_cpu,
-			(void *) cpu, &tracing_pipe_fops);
+			(void *)&data->trace_cpu, &tracing_pipe_fops);
 
 	/* per cpu trace */
 	trace_create_file("trace", 0644, d_cpu,
-			(void *) cpu, &tracing_fops);
+			(void *)&data->trace_cpu, &tracing_fops);
 
 	trace_create_file("trace_pipe_raw", 0444, d_cpu,
-			(void *) cpu, &tracing_buffers_fops);
+			(void *)&data->trace_cpu, &tracing_buffers_fops);
 
 	trace_create_file("stats", 0444, d_cpu,
-			(void *) cpu, &tracing_stats_fops);
+			(void *)&data->trace_cpu, &tracing_stats_fops);
 
 	trace_create_file("buffer_size_kb", 0444, d_cpu,
-			(void *) cpu, &tracing_entries_fops);
+			(void *)&data->trace_cpu, &tracing_entries_fops);
+
+#ifdef CONFIG_TRACER_SNAPSHOT
+	trace_create_file("snapshot", 0644, d_cpu,
+			  (void *)&data->trace_cpu, &snapshot_fops);
+
+	trace_create_file("snapshot_raw", 0444, d_cpu,
+			(void *)&data->trace_cpu, &snapshot_raw_fops);
+#endif
 }
 
 #ifdef CONFIG_FTRACE_SELFTEST
···
 struct trace_option_dentry {
 	struct tracer_opt		*opt;
 	struct tracer_flags		*flags;
+	struct trace_array		*tr;
 	struct dentry			*entry;
 };
 
···
 
 	if (!!(topt->flags->val & topt->opt->bit) != val) {
 		mutex_lock(&trace_types_lock);
-		ret = __set_tracer_option(current_trace, topt->flags,
+		ret = __set_tracer_option(topt->tr->current_trace, topt->flags,
 					  topt->opt, !val);
 		mutex_unlock(&trace_types_lock);
 		if (ret)
···
 trace_options_core_write(struct file *filp, const char __user *ubuf, size_t cnt,
 			 loff_t *ppos)
 {
+	struct trace_array *tr = &global_trace;
 	long index = (long)filp->private_data;
 	unsigned long val;
 	int ret;
···
 		return -EINVAL;
 
 	mutex_lock(&trace_types_lock);
-	ret = set_tracer_flag(1 << index, val);
+	ret = set_tracer_flag(tr, 1 << index, val);
 	mutex_unlock(&trace_types_lock);
 
 	if (ret < 0)
···
 }
 
 
-static struct dentry *trace_options_init_dentry(void)
+static struct dentry *trace_options_init_dentry(struct trace_array *tr)
 {
 	struct dentry *d_tracer;
-	static struct dentry *t_options;
 
-	if (t_options)
-		return t_options;
+	if (tr->options)
+		return tr->options;
 
-	d_tracer = tracing_init_dentry();
+	d_tracer = tracing_init_dentry_tr(tr);
 	if (!d_tracer)
 		return NULL;
 
-	t_options = debugfs_create_dir("options", d_tracer);
-	if (!t_options) {
+	tr->options = debugfs_create_dir("options", d_tracer);
+	if (!tr->options) {
 		pr_warning("Could not create debugfs directory 'options'\n");
 		return NULL;
 	}
 
-	return t_options;
+	return tr->options;
 }
 
 static void
-create_trace_option_file(struct trace_option_dentry *topt,
+create_trace_option_file(struct trace_array *tr,
+			 struct trace_option_dentry *topt,
 			 struct tracer_flags *flags,
 			 struct tracer_opt *opt)
 {
 	struct dentry *t_options;
 
-	t_options = trace_options_init_dentry();
+	t_options = trace_options_init_dentry(tr);
 	if (!t_options)
 		return;
 
 	topt->flags = flags;
 	topt->opt = opt;
+	topt->tr = tr;
 
 	topt->entry = trace_create_file(opt->name, 0644, t_options, topt,
 				    &trace_options_fops);
···
 }
 
 static struct trace_option_dentry *
-create_trace_option_files(struct tracer *tracer)
+create_trace_option_files(struct trace_array *tr, struct tracer *tracer)
 {
 	struct trace_option_dentry *topts;
 	struct tracer_flags *flags;
···
 		return NULL;
 
 	for (cnt = 0; opts[cnt].name; cnt++)
-		create_trace_option_file(&topts[cnt], flags,
+		create_trace_option_file(tr, &topts[cnt], flags,
 					 &opts[cnt]);
 
 	return topts;
···
 }
 
 static struct dentry *
-create_trace_option_core_file(const char *option, long index)
+create_trace_option_core_file(struct trace_array *tr,
+			      const char *option, long index)
 {
 	struct dentry *t_options;
 
-	t_options = trace_options_init_dentry();
+	t_options = trace_options_init_dentry(tr);
 	if (!t_options)
 		return NULL;
 
···
 				    &trace_options_core_fops);
 }
 
-static __init void create_trace_options_dir(void)
+static __init void create_trace_options_dir(struct trace_array *tr)
 {
 	struct dentry *t_options;
 	int i;
 
-	t_options = trace_options_init_dentry();
+	t_options = trace_options_init_dentry(tr);
 	if (!t_options)
 		return;
 
 	for (i = 0; trace_options[i]; i++)
-		create_trace_option_core_file(trace_options[i], i);
+		create_trace_option_core_file(tr, trace_options[i], i);
 }
 
 static ssize_t
···
 	       size_t cnt, loff_t *ppos)
 {
 	struct trace_array *tr = filp->private_data;
-	struct ring_buffer *buffer = tr->buffer;
+	struct ring_buffer *buffer = tr->trace_buffer.buffer;
 	char buf[64];
 	int r;
 
···
 		size_t cnt, loff_t *ppos)
 {
 	struct trace_array *tr = filp->private_data;
-	struct ring_buffer *buffer = tr->buffer;
+	struct ring_buffer *buffer = tr->trace_buffer.buffer;
 	unsigned long val;
 	int ret;
 
···
 		mutex_lock(&trace_types_lock);
 		if (val) {
 			ring_buffer_record_on(buffer);
-			if (current_trace->start)
-				current_trace->start(tr);
+			if (tr->current_trace->start)
+				tr->current_trace->start(tr);
 		} else {
 			ring_buffer_record_off(buffer);
-			if (current_trace->stop)
-				current_trace->stop(tr);
+			if (tr->current_trace->stop)
+				tr->current_trace->stop(tr);
 		}
 		mutex_unlock(&trace_types_lock);
 	}
···
 	.llseek		= default_llseek,
 };
 
+struct dentry *trace_instance_dir;
+
+static void
+init_tracer_debugfs(struct trace_array *tr, struct dentry *d_tracer);
+
+static void init_trace_buffers(struct trace_array *tr, struct trace_buffer *buf)
+{
+	int cpu;
+
+	for_each_tracing_cpu(cpu) {
+		memset(per_cpu_ptr(buf->data, cpu), 0, sizeof(struct trace_array_cpu));
+		per_cpu_ptr(buf->data, cpu)->trace_cpu.cpu = cpu;
+		per_cpu_ptr(buf->data, cpu)->trace_cpu.tr = tr;
+	}
+}
+
+static int
+allocate_trace_buffer(struct trace_array *tr, struct trace_buffer *buf, int size)
+{
+	enum ring_buffer_flags rb_flags;
+
+	rb_flags = trace_flags & TRACE_ITER_OVERWRITE ? RB_FL_OVERWRITE : 0;
+
+	buf->buffer = ring_buffer_alloc(size, rb_flags);
+	if (!buf->buffer)
+		return -ENOMEM;
+
+	buf->data = alloc_percpu(struct trace_array_cpu);
+	if (!buf->data) {
+		ring_buffer_free(buf->buffer);
+		return -ENOMEM;
+	}
+
+	init_trace_buffers(tr, buf);
+
+	/* Allocate the first page for all buffers */
+	set_buffer_entries(&tr->trace_buffer,
+			   ring_buffer_size(tr->trace_buffer.buffer, 0));
+
+	return 0;
+}
+
+static int allocate_trace_buffers(struct trace_array *tr, int size)
+{
+	int ret;
+
+	ret = allocate_trace_buffer(tr, &tr->trace_buffer, size);
+	if (ret)
+		return ret;
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+	ret = allocate_trace_buffer(tr, &tr->max_buffer,
+				    allocate_snapshot ? size : 1);
+	if (WARN_ON(ret)) {
+		ring_buffer_free(tr->trace_buffer.buffer);
+		free_percpu(tr->trace_buffer.data);
+		return -ENOMEM;
+	}
+	tr->allocated_snapshot = allocate_snapshot;
+
+	/*
+	 * Only the top level trace array gets its snapshot allocated
+	 * from the kernel command line.
+	 */
+	allocate_snapshot = false;
+#endif
+	return 0;
+}
+
+static int new_instance_create(const char *name)
+{
+	struct trace_array *tr;
+	int ret;
+
+	mutex_lock(&trace_types_lock);
+
+	ret = -EEXIST;
+	list_for_each_entry(tr, &ftrace_trace_arrays, list) {
+		if (tr->name && strcmp(tr->name, name) == 0)
+			goto out_unlock;
+	}
+
+	ret = -ENOMEM;
+	tr = kzalloc(sizeof(*tr), GFP_KERNEL);
+	if (!tr)
+		goto out_unlock;
+
+	tr->name = kstrdup(name, GFP_KERNEL);
+	if (!tr->name)
+		goto out_free_tr;
+
+	raw_spin_lock_init(&tr->start_lock);
+
+	tr->current_trace = &nop_trace;
+
+	INIT_LIST_HEAD(&tr->systems);
+	INIT_LIST_HEAD(&tr->events);
+
+	if (allocate_trace_buffers(tr, trace_buf_size) < 0)
+		goto out_free_tr;
+
+	/* Holder for file callbacks */
+	tr->trace_cpu.cpu = RING_BUFFER_ALL_CPUS;
+	tr->trace_cpu.tr = tr;
+
+	tr->dir = debugfs_create_dir(name, trace_instance_dir);
+	if (!tr->dir)
+		goto out_free_tr;
+
+	ret = event_trace_add_tracer(tr->dir, tr);
+	if (ret)
+		goto out_free_tr;
+
+	init_tracer_debugfs(tr, tr->dir);
+
+	list_add(&tr->list, &ftrace_trace_arrays);
+
+	mutex_unlock(&trace_types_lock);
+
+	return 0;
+
+ out_free_tr:
+	if (tr->trace_buffer.buffer)
+		ring_buffer_free(tr->trace_buffer.buffer);
+	kfree(tr->name);
+	kfree(tr);
+
+ out_unlock:
+	mutex_unlock(&trace_types_lock);
+
+	return ret;
+
+}
+
+static int instance_delete(const char *name)
+{
+	struct trace_array *tr;
+	int found = 0;
+	int ret;
+
+	mutex_lock(&trace_types_lock);
+
+	ret = -ENODEV;
+	list_for_each_entry(tr, &ftrace_trace_arrays, list) {
+		if (tr->name && strcmp(tr->name, name) == 0) {
+			found = 1;
+			break;
+		}
+	}
+	if (!found)
+		goto out_unlock;
+
+	ret = -EBUSY;
+	if (tr->ref)
+		goto out_unlock;
+
+	list_del(&tr->list);
+
+	event_trace_del_tracer(tr);
+	debugfs_remove_recursive(tr->dir);
+	free_percpu(tr->trace_buffer.data);
+	ring_buffer_free(tr->trace_buffer.buffer);
+
+	kfree(tr->name);
+	kfree(tr);
+
+	ret = 0;
+
+ out_unlock:
+	mutex_unlock(&trace_types_lock);
+
+	return ret;
+}
+
+static int instance_mkdir (struct inode *inode, struct dentry *dentry, umode_t mode)
+{
+	struct dentry *parent;
+	int ret;
+
+	/* Paranoid: Make sure the parent is the "instances" directory */
+	parent = hlist_entry(inode->i_dentry.first, struct dentry, d_alias);
+	if (WARN_ON_ONCE(parent != trace_instance_dir))
+		return -ENOENT;
+
+	/*
+	 * The inode mutex is locked, but debugfs_create_dir() will also
+	 * take the mutex. As the instances directory can not be destroyed
+	 * or changed in any other way, it is safe to unlock it, and
+	 * let the dentry try. If two users try to make the same dir at
+	 * the same time, then the new_instance_create() will determine the
+	 * winner.
+	 */
+	mutex_unlock(&inode->i_mutex);
+
+	ret = new_instance_create(dentry->d_iname);
+
+	mutex_lock(&inode->i_mutex);
+
+	return ret;
+}
+
+static int instance_rmdir(struct inode *inode, struct dentry *dentry)
+{
+	struct dentry *parent;
+	int ret;
+
+	/* Paranoid: Make sure the parent is the "instances" directory */
+	parent = hlist_entry(inode->i_dentry.first, struct dentry, d_alias);
+	if (WARN_ON_ONCE(parent != trace_instance_dir))
+		return -ENOENT;
+
+	/* The caller did a dget() on dentry */
+	mutex_unlock(&dentry->d_inode->i_mutex);
+
+	/*
+	 * The inode mutex is locked, but debugfs_create_dir() will also
+	 * take the mutex. As the instances directory can not be destroyed
+	 * or changed in any other way, it is safe to unlock it, and
+	 * let the dentry try. If two users try to make the same dir at
+	 * the same time, then the instance_delete() will determine the
+	 * winner.
+	 */
+	mutex_unlock(&inode->i_mutex);
+
+	ret = instance_delete(dentry->d_iname);
+
+	mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT);
+	mutex_lock(&dentry->d_inode->i_mutex);
+
+	return ret;
+}
+
+static const struct inode_operations instance_dir_inode_operations = {
+	.lookup		= simple_lookup,
+	.mkdir		= instance_mkdir,
+	.rmdir		= instance_rmdir,
+};
+
+static __init void create_trace_instances(struct dentry *d_tracer)
+{
+	trace_instance_dir = debugfs_create_dir("instances", d_tracer);
+	if (WARN_ON(!trace_instance_dir))
+		return;
+
+	/* Hijack the dir inode operations, to allow mkdir */
+	trace_instance_dir->d_inode->i_op = &instance_dir_inode_operations;
+}
+
+static void
+init_tracer_debugfs(struct trace_array *tr, struct dentry *d_tracer)
+{
+	int cpu;
+
+	trace_create_file("trace_options", 0644, d_tracer,
+			  tr, &tracing_iter_fops);
+
+	trace_create_file("trace", 0644, d_tracer,
+			(void *)&tr->trace_cpu, &tracing_fops);
+
+	trace_create_file("trace_pipe", 0444, d_tracer,
+			(void *)&tr->trace_cpu, &tracing_pipe_fops);
+
+	trace_create_file("buffer_size_kb", 0644, d_tracer,
+			(void *)&tr->trace_cpu, &tracing_entries_fops);
+
+	trace_create_file("buffer_total_size_kb", 0444, d_tracer,
+			  tr, &tracing_total_entries_fops);
+
+	trace_create_file("free_buffer", 0644, d_tracer,
+			  tr, &tracing_free_buffer_fops);
+
+	trace_create_file("trace_marker", 0220, d_tracer,
+			  tr, &tracing_mark_fops);
+
+	trace_create_file("trace_clock", 0644, d_tracer, tr,
+			  &trace_clock_fops);
+
+	trace_create_file("tracing_on", 0644, d_tracer,
+			    tr, &rb_simple_fops);
+
+#ifdef CONFIG_TRACER_SNAPSHOT
+	trace_create_file("snapshot", 0644, d_tracer,
+			  (void *)&tr->trace_cpu, &snapshot_fops);
+#endif
+
+	for_each_tracing_cpu(cpu)
+		tracing_init_debugfs_percpu(tr, cpu);
+
+}
+
 static __init int tracer_init_debugfs(void)
 {
 	struct dentry *d_tracer;
-	int cpu;
 
 	trace_access_lock_init();
 
 	d_tracer = tracing_init_dentry();
+	if (!d_tracer)
+		return 0;
 
-	trace_create_file("trace_options", 0644, d_tracer,
-			NULL, &tracing_iter_fops);
+	init_tracer_debugfs(&global_trace, d_tracer);
 
 	trace_create_file("tracing_cpumask", 0644, d_tracer,
-			NULL, &tracing_cpumask_fops);
-
-	trace_create_file("trace", 0644, d_tracer,
-			(void *) TRACE_PIPE_ALL_CPU, &tracing_fops);
+			&global_trace, &tracing_cpumask_fops);
 
 	trace_create_file("available_tracers", 0444, d_tracer,
 			&global_trace, &show_traces_fops);
···
 	trace_create_file("README", 0444, d_tracer,
 			NULL, &tracing_readme_fops);
 
-	trace_create_file("trace_pipe", 0444, d_tracer,
-			(void *) TRACE_PIPE_ALL_CPU, &tracing_pipe_fops);
-
-	trace_create_file("buffer_size_kb", 0644, d_tracer,
-			(void *) RING_BUFFER_ALL_CPUS, &tracing_entries_fops);
-
-	trace_create_file("buffer_total_size_kb", 0444, d_tracer,
-			&global_trace, &tracing_total_entries_fops);
-
-	trace_create_file("free_buffer", 0644, d_tracer,
-			&global_trace, &tracing_free_buffer_fops);
-
-	trace_create_file("trace_marker", 0220, d_tracer,
-			NULL, &tracing_mark_fops);
-
 	trace_create_file("saved_cmdlines", 0444, d_tracer,
 			NULL, &tracing_saved_cmdlines_fops);
-
-	trace_create_file("trace_clock", 0644, d_tracer, NULL,
-			  &trace_clock_fops);
-
-	trace_create_file("tracing_on", 0644, d_tracer,
-			    &global_trace, &rb_simple_fops);
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 	trace_create_file("dyn_ftrace_total_info", 0444, d_tracer,
 			&ftrace_update_tot_cnt, &tracing_dyn_info_fops);
 #endif
 
-#ifdef CONFIG_TRACER_SNAPSHOT
-	trace_create_file("snapshot", 0644, d_tracer,
-			  (void *) TRACE_PIPE_ALL_CPU, &snapshot_fops);
-#endif
+	create_trace_instances(d_tracer);
 
-	create_trace_options_dir();
-
-	for_each_tracing_cpu(cpu)
-		tracing_init_debugfs_percpu(cpu);
+	create_trace_options_dir(&global_trace);
 
 	return 0;
 }
···
 trace_printk_seq(struct trace_seq *s)
 {
 	/* Probably should print a warning here. */
-	if (s->len >= 1000)
-		s->len = 1000;
+	if (s->len >= TRACE_MAX_PRINT)
+		s->len = TRACE_MAX_PRINT;
 
 	/* should be zero ended, but we are paranoid. */
 	s->buffer[s->len] = 0;
···
 void trace_init_global_iter(struct trace_iterator *iter)
 {
 	iter->tr = &global_trace;
-	iter->trace = current_trace;
-	iter->cpu_file = TRACE_PIPE_ALL_CPU;
+	iter->trace = iter->tr->current_trace;
+	iter->cpu_file = RING_BUFFER_ALL_CPUS;
+	iter->trace_buffer = &global_trace.trace_buffer;
 }
 
-static void
-__ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
+void ftrace_dump(enum ftrace_dump_mode oops_dump_mode)
 {
-	static arch_spinlock_t ftrace_dump_lock =
-		(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
 	/* use static because iter can be a bit big for the stack */
 	static struct trace_iterator iter;
+	static atomic_t dump_running;
 	unsigned int old_userobj;
-	static int dump_ran;
 	unsigned long flags;
 	int cnt = 0, cpu;
 
-	/* only one dump */
-	local_irq_save(flags);
-	arch_spin_lock(&ftrace_dump_lock);
-	if (dump_ran)
-		goto out;
-
-	dump_ran = 1;
-
-	tracing_off();
-
-	/* Did function tracer already get disabled? */
-	if (ftrace_is_dead()) {
-		printk("# WARNING: FUNCTION TRACING IS CORRUPTED\n");
-		printk("#          MAY BE MISSING FUNCTION EVENTS\n");
+	/* Only allow one dump user at a time. */
+	if (atomic_inc_return(&dump_running) != 1) {
+		atomic_dec(&dump_running);
+		return;
 	}
 
-	if (disable_tracing)
-		ftrace_kill();
+	/*
+	 * Always turn off tracing when we dump.
+	 * We don't need to show trace output of what happens
+	 * between multiple crashes.
+	 *
+	 * If the user does a sysrq-z, then they can re-enable
+	 * tracing with echo 1 > tracing_on.
+	 */
+	tracing_off();
+
+	local_irq_save(flags);
 
 	/* Simulate the iterator */
 	trace_init_global_iter(&iter);
 
 	for_each_tracing_cpu(cpu) {
-		atomic_inc(&iter.tr->data[cpu]->disabled);
+		atomic_inc(&per_cpu_ptr(iter.tr->trace_buffer.data, cpu)->disabled);
 	}
 
 	old_userobj = trace_flags & TRACE_ITER_SYM_USEROBJ;
···
 
 	switch (oops_dump_mode) {
 	case DUMP_ALL:
-		iter.cpu_file = TRACE_PIPE_ALL_CPU;
+		iter.cpu_file = RING_BUFFER_ALL_CPUS;
 		break;
 	case DUMP_ORIG:
 		iter.cpu_file = raw_smp_processor_id();
···
 		goto out_enable;
 	default:
 		printk(KERN_TRACE "Bad dumping mode, switching to all CPUs dump\n");
-		iter.cpu_file = TRACE_PIPE_ALL_CPU;
+		iter.cpu_file = RING_BUFFER_ALL_CPUS;
 	}
 
 	printk(KERN_TRACE "Dumping ftrace buffer:\n");
+
+	/* Did function tracer already get disabled? */
+	if (ftrace_is_dead()) {
+		printk("# WARNING: FUNCTION TRACING IS CORRUPTED\n");
+		printk("#          MAY BE MISSING FUNCTION EVENTS\n");
+	}
 
 	/*
 	 * We need to stop all tracing on all CPUS to read the
···
 		printk(KERN_TRACE "---------------------------------\n");
 
  out_enable:
-	/* Re-enable tracing if requested */
-	if (!disable_tracing) {
-		trace_flags |= old_userobj;
+	trace_flags |= old_userobj;
 
-		for_each_tracing_cpu(cpu) {
-			atomic_dec(&iter.tr->data[cpu]->disabled);
-		}
-		tracing_on();
+	for_each_tracing_cpu(cpu) {
+		atomic_dec(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled);
 	}
-
- out:
-	arch_spin_unlock(&ftrace_dump_lock);
+ 	atomic_dec(&dump_running);
 	local_irq_restore(flags);
-}
-
-/* By default: disable tracing after the dump */
-void ftrace_dump(enum ftrace_dump_mode oops_dump_mode)
-{
-	__ftrace_dump(true, oops_dump_mode);
 }
 EXPORT_SYMBOL_GPL(ftrace_dump);
 
 __init static int tracer_alloc_buffers(void)
 {
 	int ring_buf_size;
-	enum ring_buffer_flags rb_flags;
-	int i;
 	int ret = -ENOMEM;
 
 
···
 	else
 		ring_buf_size = 1;
 
-	rb_flags = trace_flags & TRACE_ITER_OVERWRITE ? RB_FL_OVERWRITE : 0;
-
 	cpumask_copy(tracing_buffer_mask, cpu_possible_mask);
 	cpumask_copy(tracing_cpumask, cpu_all_mask);
 
+	raw_spin_lock_init(&global_trace.start_lock);
+
 	/* TODO: make the number of buffers hot pluggable with CPUS */
-	global_trace.buffer = ring_buffer_alloc(ring_buf_size, rb_flags);
-	if (!global_trace.buffer) {
+	if (allocate_trace_buffers(&global_trace, ring_buf_size) < 0) {
 		printk(KERN_ERR "tracer: failed to allocate ring buffer!\n");
 		WARN_ON(1);
 		goto out_free_cpumask;
 	}
+
 	if (global_trace.buffer_disabled)
 		tracing_off();
 
-
-#ifdef CONFIG_TRACER_MAX_TRACE
-	max_tr.buffer = ring_buffer_alloc(1, rb_flags);
-	if (!max_tr.buffer) {
-		printk(KERN_ERR "tracer: failed to allocate max ring buffer!\n");
-		WARN_ON(1);
-		ring_buffer_free(global_trace.buffer);
-		goto out_free_cpumask;
-	}
-#endif
-
-	/* Allocate the first page for all buffers */
-	for_each_tracing_cpu(i) {
-		global_trace.data[i] = &per_cpu(global_trace_cpu, i);
-		max_tr.data[i] = &per_cpu(max_tr_data, i);
-	}
-
-	set_buffer_entries(&global_trace,
-			   ring_buffer_size(global_trace.buffer, 0));
-#ifdef CONFIG_TRACER_MAX_TRACE
-	set_buffer_entries(&max_tr, 1);
-#endif
-
 	trace_init_cmdlines();
-	init_irq_work(&trace_work_wakeup, trace_wake_up);
 
 	register_tracer(&nop_trace);
+
+	global_trace.current_trace = &nop_trace;
 
 	/* All seems OK, enable tracing */
 	tracing_disabled = 0;
···
 
 	register_die_notifier(&trace_die_notifier);
 
+	global_trace.flags = TRACE_ARRAY_FL_GLOBAL;
+
+	/* Holder for file callbacks */
+	global_trace.trace_cpu.cpu = RING_BUFFER_ALL_CPUS;
+	global_trace.trace_cpu.tr = &global_trace;
+
+	INIT_LIST_HEAD(&global_trace.systems);
+	INIT_LIST_HEAD(&global_trace.events);
+	list_add(&global_trace.list, &ftrace_trace_arrays);
+
 	while (trace_boot_options) {
 		char *option;
 
 		option = strsep(&trace_boot_options, ",");
-		trace_set_options(option);
+		trace_set_options(&global_trace, option);
 	}
+
+	register_snapshot_cmd();
 
 	return 0;
 
 out_free_cpumask:
+	free_percpu(global_trace.trace_buffer.data);
+#ifdef CONFIG_TRACER_MAX_TRACE
+	free_percpu(global_trace.max_buffer.data);
+#endif
 	free_cpumask_var(tracing_cpumask);
 out_free_buffer_mask:
 	free_cpumask_var(tracing_buffer_mask);

kernel/trace/trace.h

···
 #include <linux/trace_seq.h>
 #include <linux/ftrace_event.h>
 
+#ifdef CONFIG_FTRACE_SYSCALLS
+#include <asm/unistd.h>		/* For NR_SYSCALLS	     */
+#include <asm/syscall.h>	/* some archs define it here */
+#endif
+
 enum trace_type {
 	__TRACE_FIRST_TYPE = 0,
 
···
 	TRACE_GRAPH_ENT,
 	TRACE_USER_STACK,
 	TRACE_BLK,
+	TRACE_BPUTS,
 
 	__TRACE_LAST_TYPE,
 };
···
 
 #define TRACE_BUF_SIZE		1024
 
+struct trace_array;
+
+struct trace_cpu {
+	struct trace_array	*tr;
+	struct dentry		*dir;
+	int			cpu;
+};
+
 /*
  * The CPU trace array - it consists of thousands of trace entries
  * plus some other descriptor data: (for example which task started
  * the trace, etc.)
  */
 struct trace_array_cpu {
+	struct trace_cpu	trace_cpu;
 	atomic_t		disabled;
 	void			*buffer_page;	/* ring buffer spare */
 
···
 	char			comm[TASK_COMM_LEN];
 };
 
+struct tracer;
+
+struct trace_buffer {
+	struct trace_array		*tr;
+	struct ring_buffer		*buffer;
+	struct trace_array_cpu __percpu	*data;
+	cycle_t				time_start;
+	int				cpu;
+};
+
 /*
  * The trace array - an array of per-CPU trace arrays. This is the
  * highest level data structure that individual tracers deal with.
  * They have on/off state as well:
  */
 struct trace_array {
-	struct ring_buffer	*buffer;
-	int			cpu;
+	struct list_head	list;
+	char			*name;
+	struct trace_buffer	trace_buffer;
+#ifdef CONFIG_TRACER_MAX_TRACE
+	/*
+	 * The max_buffer is used to snapshot the trace when a maximum
+	 * latency is reached, or when the user initiates a snapshot.
+	 * Some tracers will use this to store a maximum trace while
+	 * it continues examining live traces.
+	 *
+	 * The buffers for the max_buffer are set up the same as the trace_buffer
+	 * When a snapshot is taken, the buffer of the max_buffer is swapped
+	 * with the buffer of the trace_buffer and the buffers are reset for
+	 * the trace_buffer so the tracing can continue.
+	 */
+	struct trace_buffer	max_buffer;
+	bool			allocated_snapshot;
+#endif
 	int			buffer_disabled;
-	cycle_t			time_start;
+	struct trace_cpu	trace_cpu;	/* place holder */
+#ifdef CONFIG_FTRACE_SYSCALLS
+	int			sys_refcount_enter;
+	int			sys_refcount_exit;
+	DECLARE_BITMAP(enabled_enter_syscalls, NR_syscalls);
+	DECLARE_BITMAP(enabled_exit_syscalls, NR_syscalls);
+#endif
+	int			stop_count;
+	int			clock_id;
+	struct tracer		*current_trace;
+	unsigned int		flags;
+	raw_spinlock_t		start_lock;
+	struct dentry		*dir;
+	struct dentry		*options;
+	struct dentry		*percpu_dir;
+	struct dentry		*event_dir;
+	struct list_head	systems;
+	struct list_head	events;
 	struct task_struct	*waiter;
-	struct trace_array_cpu	*data[NR_CPUS];
+	int			ref;
 };
+
+enum {
+	TRACE_ARRAY_FL_GLOBAL	= (1 << 0)
+};
+
+extern struct list_head ftrace_trace_arrays;
+
+/*
+ * The global tracer (top) should be the first trace array added,
+ * but we check the flag anyway.
+ */
+static inline struct trace_array *top_trace_array(void)
+{
+	struct trace_array *tr;
+
+	tr = list_entry(ftrace_trace_arrays.prev,
+			typeof(*tr), list);
+	WARN_ON(!(tr->flags & TRACE_ARRAY_FL_GLOBAL));
+	return tr;
+}
 
 #define FTRACE_CMP_TYPE(var, type) \
 	__builtin_types_compatible_p(typeof(var), type *)
···
 		IF_ASSIGN(var, ent, struct userstack_entry, TRACE_USER_STACK);\
 		IF_ASSIGN(var, ent, struct print_entry, TRACE_PRINT);	\
 		IF_ASSIGN(var, ent, struct bprint_entry, TRACE_BPRINT);	\
+		IF_ASSIGN(var, ent, struct bputs_entry, TRACE_BPUTS);	\
 		IF_ASSIGN(var, ent, struct trace_mmiotrace_rw,		\
 			  TRACE_MMIO_RW);				\
 		IF_ASSIGN(var, ent, struct trace_mmiotrace_map,		\
···
 	struct tracer		*next;
 	struct tracer_flags	*flags;
 	bool			print_max;
-	bool			use_max_tr;
-	bool			allocated_snapshot;
 	bool			enabled;
+#ifdef CONFIG_TRACER_MAX_TRACE
+	bool			use_max_tr;
+#endif
 };
 
 
···
 	current->trace_recursion = val;
 }
 
-#define TRACE_PIPE_ALL_CPU	-1
-
 static inline struct ring_buffer_iter *
 trace_buffer_iter(struct trace_iterator *iter, int cpu)
 {
···
 
 int tracer_init(struct tracer *t, struct trace_array *tr);
 int tracing_is_enabled(void);
-void tracing_reset(struct trace_array *tr, int cpu);
-void tracing_reset_online_cpus(struct trace_array *tr);
+void tracing_reset(struct trace_buffer *buf, int cpu);
+void tracing_reset_online_cpus(struct trace_buffer *buf);
 void tracing_reset_current(int cpu);
-void tracing_reset_current_online_cpus(void);
+void tracing_reset_all_online_cpus(void);
 int tracing_open_generic(struct inode *inode, struct file *filp);
 struct dentry *trace_create_file(const char *name,
 				 umode_t mode,
···
 				 void *data,
 				 const struct file_operations *fops);
 
+struct dentry *tracing_init_dentry_tr(struct trace_array *tr);
 struct dentry *tracing_init_dentry(void);
 
 struct ring_buffer_event;
···
 #define DYN_FTRACE_TEST_NAME2 trace_selftest_dynamic_test_func2
 extern int DYN_FTRACE_TEST_NAME2(void);
 
-extern int ring_buffer_expanded;
+extern bool ring_buffer_expanded;
 extern bool tracing_selftest_disabled;
 DECLARE_PER_CPU(int, ftrace_cpu_disabled);
 
···
 		    unsigned long ip, const char *fmt, va_list args);
 int trace_array_printk(struct trace_array *tr,
 		       unsigned long ip, const char *fmt, ...);
+int trace_array_printk_buf(struct ring_buffer *buffer,
+			   unsigned long ip, const char *fmt, ...);
 void trace_printk_seq(struct trace_seq *s);
 enum print_line_t print_trace_line(struct trace_iterator *iter);
 
···
 	TRACE_ITER_STOP_ON_FREE		= 0x400000,
 	TRACE_ITER_IRQ_INFO		= 0x800000,
 	TRACE_ITER_MARKERS		= 0x1000000,
+	TRACE_ITER_FUNCTION		= 0x2000000,
 };
 
 /*
···
 
 struct ftrace_event_field {
 	struct list_head	link;
-	char			*name;
-	char			*type;
+	const char		*name;
+	const char		*type;
 	int			filter_type;
 	int			offset;
 	int			size;
···
 struct event_subsystem {
 	struct list_head	list;
 	const char		*name;
-	struct dentry		*entry;
 	struct event_filter	*filter;
-	int			nr_events;
 	int			ref_count;
+};
+
+struct ftrace_subsystem_dir {
+	struct list_head		list;
+	struct event_subsystem		*subsystem;
+	struct trace_array		*tr;
+	struct dentry			*entry;
+	int				ref_count;
+	int				nr_events;
 };
 
 #define FILTER_PRED_INVALID	((unsigned short)-1)
···
 	unsigned short		right;
 };
 
-extern struct list_head ftrace_common_fields;
-
 extern enum regex_type
 filter_parse_regex(char *buff, int len, char **search, int *not);
 extern void print_event_filter(struct ftrace_event_call *call,
 			       struct trace_seq *s);
 extern int apply_event_filter(struct ftrace_event_call *call,
 			      char *filter_string);
-extern int apply_subsystem_event_filter(struct event_subsystem *system,
+extern int apply_subsystem_event_filter(struct ftrace_subsystem_dir *dir,
 					char *filter_string);
 extern void print_subsystem_event_filter(struct event_subsystem *system,
 					 struct trace_seq *s);
 extern int filter_assign_type(const char *type);
 
-struct list_head *
-trace_get_fields(struct ftrace_event_call *event_call);
+struct ftrace_event_field *
+trace_find_event_field(struct ftrace_event_call *call, char *name);
 
 static inline int
 filter_check_discard(struct ftrace_event_call *call, void *rec,
···
 }
 
 extern void trace_event_enable_cmd_record(bool enable);
+extern int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr);
+extern int event_trace_del_tracer(struct trace_array *tr);
 
 extern struct mutex event_mutex;
 extern struct list_head ftrace_events;
···
 void trace_printk_init_buffers(void);
 void trace_printk_start_comm(void);
 int trace_keep_overwrite(struct tracer *tracer, u32 mask, int set);
-int set_tracer_flag(unsigned int mask, int enabled);
+int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled);
+
+/*
+ * Normal trace_printk() and friends allocates special buffers
+ * to do the manipulation, as well as saves the print formats
+ * into sections to display. But the trace infrastructure wants
+ * to use these without the added overhead at the price of being
+ * a bit slower (used mainly for warnings, where we don't care
+ * about performance). The internal_trace_puts() is for such
+ * a purpose.
+ */
+#define internal_trace_puts(str) __trace_puts(_THIS_IP_, str, strlen(str))
 
 #undef FTRACE_ENTRY
 #define FTRACE_ENTRY(call, struct_name, id, tstruct, print, filter)	\

kernel/trace/trace_branch.c

···
 {
 	struct ftrace_event_call *call = &event_branch;
 	struct trace_array *tr = branch_tracer;
+	struct trace_array_cpu *data;
 	struct ring_buffer_event *event;
 	struct trace_branch *entry;
 	struct ring_buffer *buffer;
···
 
 	local_irq_save(flags);
 	cpu = raw_smp_processor_id();
-	if (atomic_inc_return(&tr->data[cpu]->disabled) != 1)
+	data = per_cpu_ptr(tr->trace_buffer.data, cpu);
+	if (atomic_inc_return(&data->disabled) != 1)
 		goto out;
 
 	pc = preempt_count();
-	buffer = tr->buffer;
+	buffer = tr->trace_buffer.buffer;
 	event = trace_buffer_lock_reserve(buffer, TRACE_BRANCH,
 					  sizeof(*entry), flags, pc);
 	if (!event)
···
 		__buffer_unlock_commit(buffer, event);
 
  out:
-	atomic_dec(&tr->data[cpu]->disabled);
+	atomic_dec(&data->disabled);
 	local_irq_restore(flags);
 }
 

kernel/trace/trace_clock.c

···
 	return local_clock();
 }
 
+/*
+ * trace_jiffy_clock(): Simply use jiffies as a clock counter.
+ */
+u64 notrace trace_clock_jiffies(void)
+{
+	u64 jiffy = jiffies - INITIAL_JIFFIES;
+
+	/* Return nsecs */
+	return (u64)jiffies_to_usecs(jiffy) * 1000ULL;
+}
 
 /*
  * trace_clock_global(): special globally coherent trace clock

kernel/trace/trace_entries.h

···
 		__dynamic_array(	u32,	buf	)
 	),
 
-	F_printk("%08lx fmt:%p",
-		 __entry->ip, __entry->fmt),
+	F_printk("%pf: %s",
+		 (void *)__entry->ip, __entry->fmt),
 
 	FILTER_OTHER
 );
···
 		__dynamic_array(	char,	buf	)
 	),
 
-	F_printk("%08lx %s",
-		 __entry->ip, __entry->buf),
+	F_printk("%pf: %s",
+		 (void *)__entry->ip, __entry->buf),
+
+	FILTER_OTHER
+);
+
+FTRACE_ENTRY(bputs, bputs_entry,
+
+	TRACE_BPUTS,
+
+	F_STRUCT(
+		__field(	unsigned long,	ip	)
+		__field(	const char *,	str	)
+	),
+
+	F_printk("%pf: %s",
+		 (void *)__entry->ip, __entry->str),
 
 	FILTER_OTHER
 );

kernel/trace/trace_events.c

···
 EXPORT_SYMBOL_GPL(event_storage);
 
 LIST_HEAD(ftrace_events);
-LIST_HEAD(ftrace_common_fields);
+static LIST_HEAD(ftrace_common_fields);
 
-struct list_head *
+#define GFP_TRACE (GFP_KERNEL | __GFP_ZERO)
+
+static struct kmem_cache *field_cachep;
+static struct kmem_cache *file_cachep;
+
+/* Double loops, do not use break, only goto's work */
+#define do_for_each_event_file(tr, file)			\
+	list_for_each_entry(tr, &ftrace_trace_arrays, list) {	\
+		list_for_each_entry(file, &tr->events, list)
+
+#define do_for_each_event_file_safe(tr, file)			\
+	list_for_each_entry(tr, &ftrace_trace_arrays, list) {	\
+		struct ftrace_event_file *___n;				\
+		list_for_each_entry_safe(file, ___n, &tr->events, list)
+
+#define while_for_each_event_file()		\
+	}
+
+static struct list_head *
 trace_get_fields(struct ftrace_event_call *event_call)
 {
 	if (!event_call->class->get_fields)
 		return &event_call->class->fields;
 	return event_call->class->get_fields(event_call);
+}
+
+static struct ftrace_event_field *
+__find_event_field(struct list_head *head, char *name)
+{
+	struct ftrace_event_field *field;
+
+	list_for_each_entry(field, head, link) {
+		if (!strcmp(field->name, name))
+			return field;
+	}
+
+	return NULL;
+}
+
+struct ftrace_event_field *
+trace_find_event_field(struct ftrace_event_call *call, char *name)
+{
+	struct ftrace_event_field *field;
+	struct list_head *head;
+
+	field = __find_event_field(&ftrace_common_fields, name);
+	if (field)
+		return field;
+
+	head = trace_get_fields(call);
+	return __find_event_field(head, name);
 }
 
 static int __trace_define_field(struct list_head *head, const char *type,
···
 {
 	struct ftrace_event_field *field;
 
-	field = kzalloc(sizeof(*field), GFP_KERNEL);
+	field = kmem_cache_alloc(field_cachep, GFP_TRACE);
 	if (!field)
 		goto err;
 
-	field->name = kstrdup(name, GFP_KERNEL);
-	if (!field->name)
-		goto err;
-
-	field->type = kstrdup(type, GFP_KERNEL);
-	if (!field->type)
-		goto err;
+	field->name = name;
+	field->type = type;
 
 	if (filter_type == FILTER_OTHER)
 		field->filter_type = filter_assign_type(type);
···
 	return 0;
 
 err:
-	if (field)
-		kfree(field->name);
-	kfree(field);
+	kmem_cache_free(field_cachep, field);
 
 	return -ENOMEM;
 }
···
 	return ret;
 }
 
-void trace_destroy_fields(struct ftrace_event_call *call)
+static void trace_destroy_fields(struct ftrace_event_call *call)
 {
 	struct ftrace_event_field *field, *next;
 	struct list_head *head;
···
 	head = trace_get_fields(call);
 	list_for_each_entry_safe(field, next, head, link) {
 		list_del(&field->link);
-		kfree(field->type);
-		kfree(field->name);
-		kfree(field);
+		kmem_cache_free(field_cachep, field);
 	}
 }
 
···
 int ftrace_event_reg(struct ftrace_event_call *call,
 		     enum trace_reg type, void *data)
 {
+	struct ftrace_event_file *file = data;
+
 	switch (type) {
 	case TRACE_REG_REGISTER:
 		return tracepoint_probe_register(call->name,
 						 call->class->probe,
-						 call);
+						 file);
 	case TRACE_REG_UNREGISTER:
 		tracepoint_probe_unregister(call->name,
 					    call->class->probe,
-					    call);
+					    file);
 		return 0;
 
 #ifdef CONFIG_PERF_EVENTS
···
 
 void trace_event_enable_cmd_record(bool enable)
 {
-	struct ftrace_event_call *call;
+	struct ftrace_event_file *file;
+	struct trace_array *tr;
 
 	mutex_lock(&event_mutex);
-	list_for_each_entry(call, &ftrace_events, list) {
-		if (!(call->flags & TRACE_EVENT_FL_ENABLED))
+	do_for_each_event_file(tr, file) {
+
+		if (!(file->flags & FTRACE_EVENT_FL_ENABLED))
 			continue;
 
 		if (enable) {
 			tracing_start_cmdline_record();
-			call->flags |= TRACE_EVENT_FL_RECORDED_CMD;
+			set_bit(FTRACE_EVENT_FL_RECORDED_CMD_BIT, &file->flags);
 		} else {
 			tracing_stop_cmdline_record();
-			call->flags &= ~TRACE_EVENT_FL_RECORDED_CMD;
+			clear_bit(FTRACE_EVENT_FL_RECORDED_CMD_BIT, &file->flags);
 		}
-	}
+	} while_for_each_event_file();
 	mutex_unlock(&event_mutex);
 }
 
-static int ftrace_event_enable_disable(struct ftrace_event_call *call,
-					int enable)
+static int __ftrace_event_enable_disable(struct ftrace_event_file *file,
+					 int enable, int soft_disable)
 {
+	struct ftrace_event_call *call = file->event_call;
 	int ret = 0;
+	int disable;
 
 	switch (enable) {
 	case 0:
-		if (call->flags & TRACE_EVENT_FL_ENABLED) {
-			call->flags &= ~TRACE_EVENT_FL_ENABLED;
-			if (call->flags & TRACE_EVENT_FL_RECORDED_CMD) {
+		/*
+		 * When soft_disable is set and enable is cleared, we want
+		 * to clear the SOFT_DISABLED flag but leave the event in the
+		 * state that it was. That is, if the event was enabled and
+		 * SOFT_DISABLED isn't set, then do nothing. But if SOFT_DISABLED
+		 * is set we do not want the event to be enabled before we
+		 * clear the bit.
+		 *
+		 * When soft_disable is not set but the SOFT_MODE flag is,
+		 * we do nothing. Do not disable the tracepoint, otherwise
+		 * "soft enable"s (clearing the SOFT_DISABLED bit) wont work.
+		 */
+		if (soft_disable) {
+			disable = file->flags & FTRACE_EVENT_FL_SOFT_DISABLED;
+			clear_bit(FTRACE_EVENT_FL_SOFT_MODE_BIT, &file->flags);
+		} else
+			disable = !(file->flags & FTRACE_EVENT_FL_SOFT_MODE);
+
+		if (disable && (file->flags & FTRACE_EVENT_FL_ENABLED)) {
+			clear_bit(FTRACE_EVENT_FL_ENABLED_BIT, &file->flags);
+			if (file->flags & FTRACE_EVENT_FL_RECORDED_CMD) {
 				tracing_stop_cmdline_record();
-				call->flags &= ~TRACE_EVENT_FL_RECORDED_CMD;
+				clear_bit(FTRACE_EVENT_FL_RECORDED_CMD_BIT, &file->flags);
 			}
-			call->class->reg(call, TRACE_REG_UNREGISTER, NULL);
+			call->class->reg(call, TRACE_REG_UNREGISTER, file);
 		}
+		/* If in SOFT_MODE, just set the SOFT_DISABLE_BIT */
+		if (file->flags & FTRACE_EVENT_FL_SOFT_MODE)
+			set_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &file->flags);
 		break;
 	case 1:
-		if (!(call->flags & TRACE_EVENT_FL_ENABLED)) {
+		/*
+		 * When soft_disable is set and enable is set, we want to
+		 * register the tracepoint for the event, but leave the event
+		 * as is. That means, if the event was already enabled, we do
+		 * nothing (but set SOFT_MODE). If the event is disabled, we
+		 * set SOFT_DISABLED before enabling the event tracepoint, so
+		 * it still seems to be disabled.
+		 */
+		if (!soft_disable)
+			clear_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &file->flags);
+		else
+			set_bit(FTRACE_EVENT_FL_SOFT_MODE_BIT, &file->flags);
+
+		if (!(file->flags & FTRACE_EVENT_FL_ENABLED)) {
+
+			/* Keep the event disabled, when going to SOFT_MODE. */
+			if (soft_disable)
+				set_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &file->flags);
+
 			if (trace_flags & TRACE_ITER_RECORD_CMD) {
 				tracing_start_cmdline_record();
-				call->flags |= TRACE_EVENT_FL_RECORDED_CMD;
+				set_bit(FTRACE_EVENT_FL_RECORDED_CMD_BIT, &file->flags);
 			}
-			ret = call->class->reg(call, TRACE_REG_REGISTER, NULL);
+			ret = call->class->reg(call, TRACE_REG_REGISTER, file);
 			if (ret) {
 				tracing_stop_cmdline_record();
 				pr_info("event trace: Could not enable event "
 					"%s\n", call->name);
 				break;
 			}
-			call->flags |= TRACE_EVENT_FL_ENABLED;
+			set_bit(FTRACE_EVENT_FL_ENABLED_BIT, &file->flags);
+
+			/* WAS_ENABLED gets set but never cleared. */
+			call->flags |= TRACE_EVENT_FL_WAS_ENABLED;
 		}
 		break;
 	}
···
 	return ret;
 }
 
-static void ftrace_clear_events(void)
+static int ftrace_event_enable_disable(struct ftrace_event_file *file,
+				       int enable)
 {
-	struct ftrace_event_call *call;
+	return __ftrace_event_enable_disable(file, enable, 0);
+}
+
+static void ftrace_clear_events(struct trace_array *tr)
+{
+	struct ftrace_event_file *file;
 
 	mutex_lock(&event_mutex);
-	list_for_each_entry(call, &ftrace_events, list) {
-		ftrace_event_enable_disable(call, 0);
+	list_for_each_entry(file, &tr->events, list) {
+		ftrace_event_enable_disable(file, 0);
 	}
 	mutex_unlock(&event_mutex);
 }
···
 	if (--system->ref_count)
 		return;
 
+	list_del(&system->list);
+
 	if (filter) {
 		kfree(filter->filter_string);
 		kfree(filter);
 	}
-	kfree(system->name);
 	kfree(system);
 }
 
···
 	system->ref_count++;
 }
 
-static void put_system(struct event_subsystem *system)
+static void __get_system_dir(struct ftrace_subsystem_dir *dir)
+{
+	WARN_ON_ONCE(dir->ref_count == 0);
+	dir->ref_count++;
+	__get_system(dir->subsystem);
+}
+
+static void __put_system_dir(struct ftrace_subsystem_dir *dir)
+{
+	WARN_ON_ONCE(dir->ref_count == 0);
+	/* If the subsystem is about to be freed, the dir must be too */
+	WARN_ON_ONCE(dir->subsystem->ref_count == 1 && dir->ref_count != 1);
+
+	__put_system(dir->subsystem);
+	if (!--dir->ref_count)
+		kfree(dir);
+}
+
+static void put_system(struct ftrace_subsystem_dir *dir)
 {
 	mutex_lock(&event_mutex);
-	__put_system(system);
+	__put_system_dir(dir);
 	mutex_unlock(&event_mutex);
 }
 
 /*
  * __ftrace_set_clr_event(NULL, NULL, NULL, set) will set/unset all events.
  */
-static int __ftrace_set_clr_event(const char *match, const char *sub,
-				  const char *event, int set)
+static int __ftrace_set_clr_event(struct trace_array *tr, const char *match,
+				  const char *sub, const char *event, int set)
 {
+	struct ftrace_event_file *file;
 	struct ftrace_event_call *call;
 	int ret = -EINVAL;
 
 	mutex_lock(&event_mutex);
-	list_for_each_entry(call, &ftrace_events, list) {
+	list_for_each_entry(file, &tr->events, list) {
+
+		call = file->event_call;
 
 		if (!call->name || !call->class || !call->class->reg)
 			continue;
···
 		if (event && strcmp(event, call->name) != 0)
 			continue;
 
-		ftrace_event_enable_disable(call, set);
+		ftrace_event_enable_disable(file, set);
 
 		ret = 0;
 	}
···
 	return ret;
 }
 
-static int ftrace_set_clr_event(char *buf, int set)
+static int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set)
 {
 	char *event = NULL, *sub = NULL, *match;
 
···
 			event = NULL;
 	}
 
-	return __ftrace_set_clr_event(match, sub, event, set);
+	return __ftrace_set_clr_event(tr, match, sub, event, set);
 }
 
 /**
···
  */
 int trace_set_clr_event(const char *system, const char *event, int set)
 {
-	return __ftrace_set_clr_event(NULL, system, event, set);
+	struct trace_array *tr = top_trace_array();
+
+	return __ftrace_set_clr_event(tr, NULL, system, event, set);
 }
 EXPORT_SYMBOL_GPL(trace_set_clr_event);
 
···
 		   size_t cnt, loff_t *ppos)
 {
 	struct trace_parser parser;
+	struct seq_file *m = file->private_data;
+	struct trace_array *tr = m->private;
 	ssize_t read, ret;
 
 	if (!cnt)
···
 
 		parser.buffer[parser.idx] = 0;
 
-		ret = ftrace_set_clr_event(parser.buffer + !set, set);
+		ret = ftrace_set_clr_event(tr, parser.buffer + !set, set);
 		if (ret)
 			goto out_put;
 	}
···
 static void *
 t_next(struct seq_file *m, void *v, loff_t *pos)
 {
-	struct ftrace_event_call *call = v;
+	struct ftrace_event_file *file = v;
+	struct ftrace_event_call *call;
+	struct trace_array *tr = m->private;
 
 	(*pos)++;
 
-	list_for_each_entry_continue(call, &ftrace_events, list) {
+	list_for_each_entry_continue(file, &tr->events, list) {
+		call = file->event_call;
 		/*
 		 * The ftrace subsystem is for showing formats only.
 		 * They can not be enabled or disabled via the event files.
 		 */
 		if (call->class && call->class->reg)
-			return call;
+			return file;
 	}
 
 	return NULL;
···
 
 static void *t_start(struct seq_file *m, loff_t *pos)
 {
-	struct ftrace_event_call *call;
+	struct ftrace_event_file *file;
+	struct trace_array *tr = m->private;
 	loff_t l;
 
 	mutex_lock(&event_mutex);
 
-	call = list_entry(&ftrace_events, struct ftrace_event_call, list);
+	file = list_entry(&tr->events, struct ftrace_event_file, list);
 	for (l = 0; l <= *pos; ) {
-		call = t_next(m, call, &l);
-		if (!call)
+		file = t_next(m, file, &l);
+		if (!file)
 			break;
 	}
-	return call;
+	return file;
 }
 
 static void *
 s_next(struct seq_file *m, void *v, loff_t *pos)
 {
-	struct ftrace_event_call *call = v;
+	struct ftrace_event_file *file = v;
+	struct trace_array *tr = m->private;
 
 	(*pos)++;
 
-	list_for_each_entry_continue(call, &ftrace_events, list) {
-		if (call->flags & TRACE_EVENT_FL_ENABLED)
-			return call;
+	list_for_each_entry_continue(file, &tr->events, list) {
+		if (file->flags & FTRACE_EVENT_FL_ENABLED)
+			return file;
 	}
 
 	return NULL;
···
 
 static void *s_start(struct seq_file *m, loff_t *pos)
 {
-	struct ftrace_event_call *call;
+	struct ftrace_event_file *file;
+	struct trace_array *tr = m->private;
 	loff_t l;
 
 	mutex_lock(&event_mutex);
 
-	call = list_entry(&ftrace_events, struct ftrace_event_call, list);
+	file = list_entry(&tr->events, struct ftrace_event_file, list);
 	for (l = 0; l <= *pos; ) {
-		call = s_next(m, call, &l);
-		if (!call)
+		file = s_next(m, file, &l);
+		if (!file)
 			break;
 	}
-	return call;
+	return file;
 }
 
 static int t_show(struct seq_file *m, void *v)
 {
-	struct ftrace_event_call *call = v;
+	struct ftrace_event_file *file = v;
+	struct ftrace_event_call *call = file->event_call;
 
 	if (strcmp(call->class->system, TRACE_SYSTEM) != 0)
 		seq_printf(m, "%s:", call->class->system);
···
 event_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
 		  loff_t *ppos)
 {
-	struct ftrace_event_call *call = filp->private_data;
+	struct ftrace_event_file *file = filp->private_data;
 	char *buf;
 
-	if (call->flags & TRACE_EVENT_FL_ENABLED)
-		buf = "1\n";
-	else
+	if (file->flags & FTRACE_EVENT_FL_ENABLED) {
+		if (file->flags & FTRACE_EVENT_FL_SOFT_DISABLED)
+			buf = "0*\n";
+		else
+			buf = "1\n";
+	} else
 		buf = "0\n";
 
-	return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);
+	return simple_read_from_buffer(ubuf, cnt, ppos, buf, strlen(buf));
 }
 
 static ssize_t
 event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
 		   loff_t *ppos)
 {
-	struct ftrace_event_call *call = filp->private_data;
+	struct ftrace_event_file *file = filp->private_data;
 	unsigned long val;
 	int ret;
+
+	if (!file)
+		return -EINVAL;
 
 	ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
 	if (ret)
···
 	case 0:
 	case 1:
 		mutex_lock(&event_mutex);
-		ret = ftrace_event_enable_disable(call, val);
+		ret = ftrace_event_enable_disable(file, val);
 		mutex_unlock(&event_mutex);
 		break;
 
···
 		   loff_t *ppos)
 {
 	const char set_to_char[4] = { '?', '0', '1', 'X' };
-	struct event_subsystem *system = filp->private_data;
+	struct ftrace_subsystem_dir *dir = filp->private_data;
+	struct event_subsystem *system = dir->subsystem;
 	struct ftrace_event_call *call;
+	struct ftrace_event_file *file;
+	struct trace_array *tr = dir->tr;
 	char buf[2];
 	int set = 0;
 	int ret;
 
 	mutex_lock(&event_mutex);
-	list_for_each_entry(call, &ftrace_events, list) {
+	list_for_each_entry(file, &tr->events, list) {
+		call = file->event_call;
 		if (!call->name || !call->class || !call->class->reg)
 			continue;
 
···
 		 * or if all events or cleared, or if we have
 		 * a mixture.
 		 */
-		set |= (1 << !!(call->flags & TRACE_EVENT_FL_ENABLED));
+		set |= (1 << !!(file->flags & FTRACE_EVENT_FL_ENABLED));
 
 		/*
 		 * If we have a mixture, no need to look further.
···
 system_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
 		    loff_t *ppos)
 {
-	struct event_subsystem *system = filp->private_data;
+	struct ftrace_subsystem_dir *dir = filp->private_data;
+	struct event_subsystem *system = dir->subsystem;
 	const char *name = NULL;
 	unsigned long val;
 	ssize_t ret;
···
 	if (system)
 		name = system->name;
 
-	ret = __ftrace_set_clr_event(NULL, name, NULL, val);
+	ret = __ftrace_set_clr_event(dir->tr, NULL, name, NULL, val);
 	if (ret)
 		goto out;
 
···
 static int subsystem_open(struct inode *inode, struct file *filp)
 {
 	struct event_subsystem *system = NULL;
+	struct ftrace_subsystem_dir *dir = NULL; /* Initialize for gcc */
+	struct trace_array *tr;
 	int ret;
-
-	if (!inode->i_private)
-		goto skip_search;
 
 	/* Make sure the system still exists */
 	mutex_lock(&event_mutex);
-	list_for_each_entry(system, &event_subsystems, list) {
-		if (system == inode->i_private) {
-			/* Don't open systems with no events */
-			if (!system->nr_events) {
-				system = NULL;
-				break;
+	list_for_each_entry(tr, &ftrace_trace_arrays, list) {
+		list_for_each_entry(dir, &tr->systems, list) {
+			if (dir == inode->i_private) {
+				/* Don't open systems with no events */
+				if (dir->nr_events) {
+					__get_system_dir(dir);
+					system = dir->subsystem;
+				}
+				goto exit_loop;
 			}
-			__get_system(system);
-			break;
 		}
 	}
+ exit_loop:
 	mutex_unlock(&event_mutex);
 
-	if (system != inode->i_private)
+	if (!system)
 		return -ENODEV;
 
- skip_search:
+	/* Some versions of gcc think dir can be uninitialized here */
+	WARN_ON(!dir);
+
 	ret = tracing_open_generic(inode, filp);
-	if (ret < 0 && system)
-		put_system(system);
+	if (ret < 0)
+		put_system(dir);
+
+	return ret;
+}
+
+static int system_tr_open(struct inode *inode, struct file *filp)
+{
+	struct ftrace_subsystem_dir *dir;
+	struct trace_array *tr = inode->i_private;
+	int ret;
+
+	/* Make a temporary dir that has no system but points to tr */
+	dir = kzalloc(sizeof(*dir), GFP_KERNEL);
+	if (!dir)
+		return -ENOMEM;
+
+	dir->tr = tr;
+
+	ret = tracing_open_generic(inode, filp);
+	if (ret < 0)
+		kfree(dir);
+
+	filp->private_data = dir;
 
 	return ret;
 }
 
 static int subsystem_release(struct inode *inode, struct file *file)
 {
-	struct event_subsystem *system = inode->i_private;
+	struct ftrace_subsystem_dir *dir = file->private_data;
 
-	if (system)
-		put_system(system);
+	/*
+	 * If dir->subsystem is NULL, then this is a temporary
+	 * descriptor that was made for a trace_array to enable
+	 * all subsystems.
+	 */
+	if (dir->subsystem)
+		put_system(dir);
+	else
+		kfree(dir);
 
 	return 0;
 }
···
 subsystem_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
 		      loff_t *ppos)
 {
-	struct event_subsystem *system = filp->private_data;
+	struct ftrace_subsystem_dir *dir = filp->private_data;
+	struct event_subsystem *system = dir->subsystem;
 	struct trace_seq *s;
 	int r;
 
···
 subsystem_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
 		       loff_t *ppos)
 {
-	struct event_subsystem *system = filp->private_data;
+	struct ftrace_subsystem_dir *dir = filp->private_data;
 	char *buf;
 	int err;
 
···
 	}
 	buf[cnt] = '\0';
 
-	err = apply_subsystem_event_filter(system, buf);
+	err = apply_subsystem_event_filter(dir, buf);
 	free_page((unsigned long) buf);
 	if (err < 0)
 		return err;
···
 	.release = subsystem_release,
 };
 
+static const struct file_operations ftrace_tr_enable_fops = {
+	.open = system_tr_open,
+	.read = system_enable_read,
+	.write = system_enable_write,
+	.llseek = default_llseek,
+	.release = subsystem_release,
+};
+
 static const struct file_operations ftrace_show_header_fops = {
 	.open = tracing_open_generic,
 	.read = show_header,
 	.llseek = default_llseek,
 };
 
-static struct dentry *event_trace_events_dir(void)
+static int
+ftrace_event_open(struct inode *inode, struct file *file,
+		  const struct seq_operations *seq_ops)
 {
-	static struct dentry *d_tracer;
-	static struct dentry *d_events;
+	struct seq_file *m;
+	int ret;
 
-	if (d_events)
-		return d_events;
+	ret = seq_open(file, seq_ops);
+	if (ret < 0)
+		return ret;
+	m = file->private_data;
+	/* copy tr over to seq ops */
+	m->private = inode->i_private;
 
-	d_tracer = tracing_init_dentry();
-	if (!d_tracer)
-		return NULL;
-
-	d_events = debugfs_create_dir("events", d_tracer);
-	if (!d_events)
-		pr_warning("Could not create debugfs "
-			   "'events' directory\n");
-
-	return d_events;
+	return ret;
 }
 
 static int
···
 {
 	const struct seq_operations *seq_ops = &show_event_seq_ops;
 
-	return seq_open(file, seq_ops);
+	return ftrace_event_open(inode, file, seq_ops);
 }
 
 static int
 ftrace_event_set_open(struct inode *inode, struct file *file)
 {
 	const struct seq_operations *seq_ops = &show_set_event_seq_ops;
+	struct trace_array *tr = inode->i_private;
 
 	if ((file->f_mode & FMODE_WRITE) &&
 	    (file->f_flags & O_TRUNC))
-		ftrace_clear_events();
+		ftrace_clear_events(tr);
 
-	return seq_open(file, seq_ops);
+	return ftrace_event_open(inode, file, seq_ops);
 }
 
-static struct dentry *
-event_subsystem_dir(const char *name, struct dentry *d_events)
+static struct event_subsystem *
+create_new_subsystem(const char *name)
 {
 	struct event_subsystem *system;
-	struct dentry *entry;
-
-	/* First see if we did not already create this dir */
-	list_for_each_entry(system, &event_subsystems, list) {
-		if (strcmp(system->name, name) == 0) {
-			system->nr_events++;
-			return system->entry;
-		}
-	}
 
 	/* need to create new entry */
 	system = kmalloc(sizeof(*system), GFP_KERNEL);
-	if (!system) {
-		pr_warning("No memory to create event subsystem %s\n",
-			   name);
-		return d_events;
-	}
+	if (!system)
+		return NULL;
 
-	system->entry = debugfs_create_dir(name, d_events);
-	if (!system->entry) {
-		pr_warning("Could not create event subsystem %s\n",
-			   name);
-		kfree(system);
-		return d_events;
-	}
-
-	system->nr_events = 1;
 	system->ref_count = 1;
-	system->name = kstrdup(name, GFP_KERNEL);
-	if (!system->name) {
-		debugfs_remove(system->entry);
-		kfree(system);
-		return d_events;
-	}
-
-	list_add(&system->list, &event_subsystems);
+	system->name = name;
 
 	system->filter = NULL;
 
 	system->filter = kzalloc(sizeof(struct event_filter), GFP_KERNEL);
-	if (!system->filter) {
-		pr_warning("Could not allocate filter for subsystem "
-			   "'%s'\n", name);
-		return system->entry;
+	if (!system->filter)
+		goto out_free;
+
+	list_add(&system->list, &event_subsystems);
+
+	return system;
+
+ out_free:
+	kfree(system);
+	return NULL;
+}
+
+static struct dentry *
+event_subsystem_dir(struct trace_array *tr, const char *name,
+		    struct ftrace_event_file *file, struct dentry *parent)
+{
+	struct ftrace_subsystem_dir *dir;
+	struct event_subsystem *system;
+	struct dentry *entry;
+
+	/* First see if we did not already create this dir */
+	list_for_each_entry(dir, &tr->systems, list) {
+		system = dir->subsystem;
+		if (strcmp(system->name, name) == 0) {
+			dir->nr_events++;
+			file->system = dir;
+			return dir->entry;
+		}
 	}
 
-	entry = debugfs_create_file("filter", 0644, system->entry, system,
+	/* Now see if the system itself exists. */
+	list_for_each_entry(system, &event_subsystems, list) {
+		if (strcmp(system->name, name) == 0)
+			break;
+	}
+	/* Reset system variable when not found */
+	if (&system->list == &event_subsystems)
+		system = NULL;
+
+	dir = kmalloc(sizeof(*dir), GFP_KERNEL);
+	if (!dir)
+		goto out_fail;
+
+	if (!system) {
+		system = create_new_subsystem(name);
+		if (!system)
+			goto out_free;
+	} else
+		__get_system(system);
+
+	dir->entry = debugfs_create_dir(name, parent);
+	if (!dir->entry) {
+		pr_warning("Failed to create system directory %s\n", name);
+		__put_system(system);
+		goto out_free;
+	}
+
+	dir->tr = tr;
+	dir->ref_count = 1;
+	dir->nr_events = 1;
+	dir->subsystem = system;
+	file->system = dir;
+
+	entry = debugfs_create_file("filter", 0644, dir->entry, dir,
 				    &ftrace_subsystem_filter_fops);
 	if (!entry) {
 		kfree(system->filter);
 		system->filter = NULL;
-		pr_warning("Could not create debugfs "
-			   "'%s/filter' entry\n", name);
+		pr_warning("Could not create debugfs '%s/filter' entry\n", name);
 	}
 
-	trace_create_file("enable", 0644, system->entry, system,
+	trace_create_file("enable", 0644, dir->entry, dir,
 			  &ftrace_system_enable_fops);
 
-	return system->entry;
+	list_add(&dir->list, &tr->systems);
+
+	return dir->entry;
+
+ out_free:
+	kfree(dir);
+ out_fail:
+	/* Only print this message if failed on memory allocation */
+	if (!dir || !system)
+		pr_warning("No memory to create event subsystem %s\n",
+			   name);
+	return NULL;
 }
 
 static int
-event_create_dir(struct ftrace_event_call *call, struct dentry *d_events,
+event_create_dir(struct dentry *parent,
+		 struct ftrace_event_file *file,
 		 const struct file_operations *id,
 		 const struct file_operations *enable,
 		 const struct file_operations *filter,
 		 const struct file_operations *format)
 {
+	struct ftrace_event_call *call = file->event_call;
+	struct trace_array *tr = file->tr;
 	struct list_head *head;
+	struct dentry *d_events;
 	int ret;
 
 	/*
 	 * If the trace point header did not define TRACE_SYSTEM
 	 * then the system would be called "TRACE_SYSTEM".
 	 */
-	if (strcmp(call->class->system, TRACE_SYSTEM) != 0)
-		d_events = event_subsystem_dir(call->class->system, d_events);
+	if (strcmp(call->class->system, TRACE_SYSTEM) != 0) {
+		d_events = event_subsystem_dir(tr, call->class->system, file, parent);
+		if (!d_events)
+			return -ENOMEM;
+	} else
+		d_events = parent;
 
-	call->dir = debugfs_create_dir(call->name, d_events);
-	if (!call->dir) {
-		pr_warning("Could not create debugfs "
-			   "'%s' directory\n", call->name);
+	file->dir = debugfs_create_dir(call->name, d_events);
+	if (!file->dir) {
+		pr_warning("Could not create debugfs '%s' directory\n",
+			   call->name);
 		return -1;
 	}
 
 	if (call->class->reg && !(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE))
-		trace_create_file("enable", 0644, call->dir, call,
+		trace_create_file("enable", 0644, file->dir, file,
 				  enable);
 
 #ifdef CONFIG_PERF_EVENTS
 	if (call->event.type && call->class->reg)
-		trace_create_file("id", 0444, call->dir, call,
+		trace_create_file("id", 0444, file->dir, call,
 		 		  id);
 #endif
 
···
 		if (ret < 0) {
 			pr_warning("Could not initialize trace point"
 				   " events/%s\n", call->name);
-			return ret;
+			return -1;
 		}
 	}
-	trace_create_file("filter", 0644, call->dir, call,
+	trace_create_file("filter", 0644, file->dir, call,
 			  filter);
 
-	trace_create_file("format", 0444, call->dir, call,
+	trace_create_file("format", 0444, file->dir, call,
 			  format);
 
 	return 0;
 }
 
+static void remove_subsystem(struct ftrace_subsystem_dir *dir)
+{
+	if (!dir)
+		return;
+
+	if (!--dir->nr_events) {
+		debugfs_remove_recursive(dir->entry);
+		list_del(&dir->list);
+		__put_system_dir(dir);
+	}
+}
+
+static void remove_event_from_tracers(struct ftrace_event_call *call)
+{
+	struct ftrace_event_file *file;
+	struct trace_array *tr;
+
+	do_for_each_event_file_safe(tr, file) {
+
+		if (file->event_call != call)
+			continue;
+
+		list_del(&file->list);
+		debugfs_remove_recursive(file->dir);
+		remove_subsystem(file->system);
+		kmem_cache_free(file_cachep, file);
+
+		/*
+		 * The do_for_each_event_file_safe() is
+		 * a double loop. After finding the call for this
+		 * trace_array, we use break to jump to the next
+		 * trace_array.
+		 */
+		break;
+	} while_for_each_event_file();
+}
+
 static void event_remove(struct ftrace_event_call *call)
 {
-	ftrace_event_enable_disable(call, 0);
+	struct trace_array *tr;
+	struct ftrace_event_file *file;
+
+	do_for_each_event_file(tr, file) {
+		if (file->event_call != call)
+			continue;
+		ftrace_event_enable_disable(file, 0);
+		/*
+		 * The do_for_each_event_file() is
+		 * a double loop. After finding the call for this
+		 * trace_array, we use break to jump to the next
+		 * trace_array.
+		 */
+		break;
+	} while_for_each_event_file();
+
 	if (call->event.funcs)
 		__unregister_ftrace_event(&call->event);
+	remove_event_from_tracers(call);
 	list_del(&call->list);
 }
 
···
 }
 
 static int
-__trace_add_event_call(struct ftrace_event_call *call, struct module *mod,
-		       const struct file_operations *id,
-		       const struct file_operations *enable,
-		       const struct file_operations *filter,
-		       const struct file_operations *format)
+__register_event(struct ftrace_event_call *call, struct module *mod)
 {
-	struct dentry *d_events;
 	int ret;
 
 	ret = event_init(call);
 	if (ret < 0)
 		return ret;
 
-	d_events = event_trace_events_dir();
-	if (!d_events)
-		return -ENOENT;
-
-	ret = event_create_dir(call, d_events, id, enable, filter, format);
-	if (!ret)
-		list_add(&call->list, &ftrace_events);
+	list_add(&call->list, &ftrace_events);
 	call->mod = mod;
 
-	return ret;
+	return 0;
 }
+
+/* Add an event to a trace directory */
+static int
+__trace_add_new_event(struct ftrace_event_call *call,
+		      struct trace_array *tr,
+		      const struct file_operations *id,
+		      const struct file_operations *enable,
+		      const struct file_operations *filter,
+		      const struct file_operations *format)
+{
+	struct ftrace_event_file *file;
+
+	file = kmem_cache_alloc(file_cachep, GFP_TRACE);
+	if (!file)
+		return -ENOMEM;
+
+	file->event_call = call;
+	file->tr = tr;
+	list_add(&file->list, &tr->events);
+
+	return event_create_dir(tr->event_dir, file, id, enable, filter, format);
+}
+
+/*
+ * Just create a decriptor for early init. A descriptor is required
+ * for enabling events at boot. We want to enable events before
+ * the filesystem is initialized.
+ */
+static __init int
+__trace_early_add_new_event(struct ftrace_event_call *call,
+			    struct trace_array *tr)
+{
+	struct ftrace_event_file *file;
+
+	file = kmem_cache_alloc(file_cachep, GFP_TRACE);
+	if (!file)
+		return -ENOMEM;
+
+	file->event_call = call;
+	file->tr = tr;
+	list_add(&file->list, &tr->events);
+
+	return 0;
+}
+
+struct ftrace_module_file_ops;
+static void __add_event_to_tracers(struct ftrace_event_call *call,
+				   struct ftrace_module_file_ops *file_ops);
 
 /* Add an additional event_call dynamically */
 int trace_add_event_call(struct ftrace_event_call *call)
 {
 	int ret;
 	mutex_lock(&event_mutex);
-	ret = __trace_add_event_call(call, NULL, &ftrace_event_id_fops,
-				     &ftrace_enable_fops,
-				     &ftrace_event_filter_fops,
-				     &ftrace_event_format_fops);
+
+	ret = __register_event(call, NULL);
+	if (ret >= 0)
+		__add_event_to_tracers(call, NULL);
+
 	mutex_unlock(&event_mutex);
 	return ret;
 }
 
-static void remove_subsystem_dir(const char *name)
-{
-	struct event_subsystem *system;
-
-	if (strcmp(name, TRACE_SYSTEM) == 0)
-		return;
-
-	list_for_each_entry(system, &event_subsystems, list) {
-		if (strcmp(system->name, name) == 0) {
-			if (!--system->nr_events) {
-				debugfs_remove_recursive(system->entry);
-				list_del(&system->list);
-				__put_system(system);
-			}
-			break;
-		}
-	}
-}
-
 /*
- * Must be called under locking both of event_mutex and trace_event_mutex.
+ * Must be called under locking both of event_mutex and trace_event_sem.
  */
 static void __trace_remove_event_call(struct ftrace_event_call *call)
 {
 	event_remove(call);
 	trace_destroy_fields(call);
 	destroy_preds(call);
-	debugfs_remove_recursive(call->dir);
-	remove_subsystem_dir(call->class->system);
 }
 
 /* Remove an event_call */
 void trace_remove_event_call(struct ftrace_event_call *call)
 {
 	mutex_lock(&event_mutex);
-	down_write(&trace_event_mutex);
+	down_write(&trace_event_sem);
 	__trace_remove_event_call(call);
-	up_write(&trace_event_mutex);
+	up_write(&trace_event_sem);
 	mutex_unlock(&event_mutex);
 }
 
···
 	struct file_operations		format;
 	struct file_operations		filter;
 };
+
+static struct ftrace_module_file_ops *
+find_ftrace_file_ops(struct ftrace_module_file_ops *file_ops, struct module *mod)
+{
+	/*
+	 * As event_calls are added in groups by module,
+	 * when we find one file_ops, we don't need to search for
+	 * each call in that module, as the rest should be the
+	 * same. Only search for a new one if the last one did
+	 * not match.
+	 */
+	if (file_ops && mod == file_ops->mod)
+		return file_ops;
+
+	list_for_each_entry(file_ops, &ftrace_module_file_list, list) {
+		if (file_ops->mod == mod)
+			return file_ops;
+	}
+	return NULL;
+}
 
 static struct ftrace_module_file_ops *
 trace_create_file_ops(struct module *mod)
···
 		return;
 
 	for_each_event(call, start, end) {
-		__trace_add_event_call(*call, mod,
-				       &file_ops->id, &file_ops->enable,
-				       &file_ops->filter, &file_ops->format);
+		__register_event(*call, mod);
+		__add_event_to_tracers(*call, file_ops);
 	}
 }
 
···
 {
 	struct ftrace_module_file_ops *file_ops;
 	struct ftrace_event_call *call, *p;
-	bool found = false;
+	bool clear_trace = false;
 
-	down_write(&trace_event_mutex);
+	down_write(&trace_event_sem);
 	list_for_each_entry_safe(call, p, &ftrace_events, list) {
 		if (call->mod == mod) {
-			found = true;
+			if (call->flags & TRACE_EVENT_FL_WAS_ENABLED)
+				clear_trace = true;
 			__trace_remove_event_call(call);
 		}
 	}
···
 		list_del(&file_ops->list);
 		kfree(file_ops);
 	}
+	up_write(&trace_event_sem);
 
 	/*
 	 * It is safest to reset the ring buffer if the module being unloaded
-	 * registered any events.
+	 * registered any events that were used. The only worry is if
+	 * a new module gets loaded, and takes on the same id as the events
+	 * of this module. When printing out the buffer, traced events left
+	 * over from this module may be passed to the new module events and
+	 * unexpected results may occur.
 	 */
-	if (found)
-		tracing_reset_current_online_cpus();
-	up_write(&trace_event_mutex);
+	if (clear_trace)
+		tracing_reset_all_online_cpus();
 }
 
 static int trace_module_notify(struct notifier_block *self,
···
 
 	return 0;
 }
+
+static int
+__trace_add_new_mod_event(struct ftrace_event_call *call,
+			  struct trace_array *tr,
+			  struct ftrace_module_file_ops *file_ops)
+{
+	return __trace_add_new_event(call, tr,
+				     &file_ops->id, &file_ops->enable,
+				     &file_ops->filter, &file_ops->format);
+}
+
 #else
-static int trace_module_notify(struct notifier_block *self,
-			       unsigned long val, void *data)
+static inline struct ftrace_module_file_ops *
+find_ftrace_file_ops(struct ftrace_module_file_ops *file_ops, struct module *mod)
+{
+	return NULL;
+}
+static inline int trace_module_notify(struct notifier_block *self,
+				      unsigned long val, void *data)
 {
 	return 0;
 }
+static inline int
+__trace_add_new_mod_event(struct ftrace_event_call *call,
+			  struct trace_array *tr,
+			  struct ftrace_module_file_ops *file_ops)
+{
+	return -ENODEV;
+}
 #endif /* CONFIG_MODULES */
+
+/* Create a new event directory structure for a trace directory. */
+static void
+__trace_add_event_dirs(struct trace_array *tr)
+{
+	struct ftrace_module_file_ops *file_ops = NULL;
+	struct ftrace_event_call *call;
+	int ret;
+
+	list_for_each_entry(call, &ftrace_events, list) {
+		if (call->mod) {
+			/*
+			 * Directories for events by modules need to
+			 * keep module ref counts when opened (as we don't
+			 * want the module to disappear when reading one
+			 * of these files). The file_ops keep account of
+			 * the module ref count.
+			 */
+			file_ops = find_ftrace_file_ops(file_ops, call->mod);
+			if (!file_ops)
+				continue; /* Warn? */
+			ret = __trace_add_new_mod_event(call, tr, file_ops);
+			if (ret < 0)
+				pr_warning("Could not create directory for event %s\n",
+					   call->name);
+			continue;
+		}
+		ret = __trace_add_new_event(call, tr,
+					    &ftrace_event_id_fops,
+					    &ftrace_enable_fops,
+					    &ftrace_event_filter_fops,
+					    &ftrace_event_format_fops);
+		if (ret < 0)
+			pr_warning("Could not create directory for event %s\n",
+				   call->name);
+	}
+}
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+/* Avoid typos */
+#define ENABLE_EVENT_STR	"enable_event"
+#define DISABLE_EVENT_STR	"disable_event"
+
+struct event_probe_data {
+	struct ftrace_event_file	*file;
+	unsigned long			count;
+	int				ref;
+	bool				enable;
+};
+
+static struct ftrace_event_file *
+find_event_file(struct trace_array *tr, const char *system,  const char *event)
+{
+	struct ftrace_event_file *file;
+	struct ftrace_event_call *call;
+
+	list_for_each_entry(file, &tr->events, list) {
+
+		call = file->event_call;
+
+		if (!call->name || !call->class || !call->class->reg)
+			continue;
+
+		if (call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)
+			continue;
+
+		if (strcmp(event, call->name) == 0 &&
+		    strcmp(system, call->class->system) == 0)
+			return file;
+	}
+	return NULL;
+}
+
+static void
+event_enable_probe(unsigned long ip, unsigned long parent_ip, void **_data)
+{
+	struct event_probe_data **pdata = (struct event_probe_data **)_data;
+	struct event_probe_data *data = *pdata;
+
+	if (!data)
+		return;
+
+	if (data->enable)
+		clear_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &data->file->flags);
+	else
+		set_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &data->file->flags);
+}
+
+static void
+event_enable_count_probe(unsigned long ip, unsigned long parent_ip, void **_data)
+{
+	struct event_probe_data **pdata = (struct event_probe_data **)_data;
+	struct event_probe_data *data = *pdata;
+
+	if (!data)
+		return;
+
+	if (!data->count)
+		return;
+
+	/* Skip if the event is in a state we want to switch to */
+	if (data->enable == !(data->file->flags & FTRACE_EVENT_FL_SOFT_DISABLED))
+		return;
+
+	if (data->count != -1)
+		(data->count)--;
+
+	event_enable_probe(ip, parent_ip, _data);
+}
+
+static int
+event_enable_print(struct seq_file *m, unsigned long ip,
+		      struct ftrace_probe_ops *ops, void *_data)
+{
+	struct event_probe_data *data = _data;
+
+	seq_printf(m, "%ps:", (void *)ip);
+
+	seq_printf(m, "%s:%s:%s",
+		   data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR,
+		   data->file->event_call->class->system,
+		   data->file->event_call->name);
+
+	if (data->count == -1)
+		seq_printf(m, ":unlimited\n");
+	else
+		seq_printf(m, ":count=%ld\n", data->count);
+
+	return 0;
+}
+
+static int
+event_enable_init(struct ftrace_probe_ops *ops, unsigned long ip,
+		  void **_data)
+{
+	struct event_probe_data **pdata = (struct event_probe_data **)_data;
+	struct event_probe_data *data = *pdata;
+
+	data->ref++;
+	return 0;
+}
+
+static void
+event_enable_free(struct ftrace_probe_ops *ops, unsigned long ip,
+		  void **_data)
+{
+	struct event_probe_data **pdata = (struct event_probe_data **)_data;
+	struct event_probe_data *data = *pdata;
+
+	if (WARN_ON_ONCE(data->ref <= 0))
+		return;
+
+	data->ref--;
+	if (!data->ref) {
+		/* Remove the SOFT_MODE flag */
+		__ftrace_event_enable_disable(data->file, 0, 1);
+		module_put(data->file->event_call->mod);
+		kfree(data);
+	}
+	*pdata = NULL;
+}
+
+static struct ftrace_probe_ops event_enable_probe_ops = {
+	.func			= event_enable_probe,
+	.print			= event_enable_print,
+	.init			= event_enable_init,
+	.free			= event_enable_free,
+};
+
+static struct ftrace_probe_ops event_enable_count_probe_ops = {
+	.func			= event_enable_count_probe,
+	.print			= event_enable_print,
+	.init			= event_enable_init,
+	.free			= event_enable_free,
+};
+
+static struct ftrace_probe_ops event_disable_probe_ops = {
+	.func			= event_enable_probe,
+	.print			= event_enable_print,
+	.init			= event_enable_init,
+	.free			= event_enable_free,
+};
+
+static struct ftrace_probe_ops event_disable_count_probe_ops = {
+	.func			= event_enable_count_probe,
+	.print			= event_enable_print,
+	.init			= event_enable_init,
+	.free			= event_enable_free,
+};
+
+static int
+event_enable_func(struct ftrace_hash *hash,
+		  char *glob, char *cmd, char *param, int enabled)
+{
+	struct trace_array *tr = top_trace_array();
+	struct ftrace_event_file *file;
+	struct ftrace_probe_ops *ops;
+	struct event_probe_data *data;
+	const char *system;
+	const char *event;
+	char *number;
+	bool enable;
+	int ret;
+
+	/* hash funcs only work with set_ftrace_filter */
+	if (!enabled)
+		return -EINVAL;
+
+	if (!param)
+		return -EINVAL;
+
+	system = strsep(&param, ":");
+	if (!param)
+		return -EINVAL;
+
+	event = strsep(&param, ":");
+
+	mutex_lock(&event_mutex);
+
+	ret = -EINVAL;
+	file = find_event_file(tr, system, event);
+	if (!file)
+		goto out;
+
+	enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
+
+	if (enable)
+		ops = param ? &event_enable_count_probe_ops : &event_enable_probe_ops;
+	else
+		ops = param ? &event_disable_count_probe_ops : &event_disable_probe_ops;
+
+	if (glob[0] == '!') {
+		unregister_ftrace_function_probe_func(glob+1, ops);
+		ret = 0;
+		goto out;
+	}
+
+	ret = -ENOMEM;
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		goto out;
+
+	data->enable = enable;
+	data->count = -1;
+	data->file = file;
+
+	if (!param)
+		goto out_reg;
+
+	number = strsep(&param, ":");
+
+	ret = -EINVAL;
+	if (!strlen(number))
+		goto out_free;
+
+	/*
+	 * We use the callback data field (which is a pointer)
+	 * as our counter.
+	 */
+	ret = kstrtoul(number, 0, &data->count);
+	if (ret)
+		goto out_free;
+
+ out_reg:
+	/* Don't let event modules unload while probe registered */
+	ret = try_module_get(file->event_call->mod);
+	if (!ret)
+		goto out_free;
+
+	ret = __ftrace_event_enable_disable(file, 1, 1);
+	if (ret < 0)
+		goto out_put;
+	ret = register_ftrace_function_probe(glob, ops, data);
+	if (!ret)
+		goto out_disable;
+ out:
+	mutex_unlock(&event_mutex);
+	return ret;
+
+ out_disable:
+	__ftrace_event_enable_disable(file, 0, 1);
+ out_put:
+	module_put(file->event_call->mod);
+ out_free:
+	kfree(data);
+	goto out;
+}
+
+static struct ftrace_func_command event_enable_cmd = {
+	.name			= ENABLE_EVENT_STR,
+	.func			= event_enable_func,
+};
+
+static struct ftrace_func_command event_disable_cmd = {
+	.name			= DISABLE_EVENT_STR,
+	.func			= event_enable_func,
+};
+
+static __init int register_event_cmds(void)
+{
+	int ret;
+
+	ret = register_ftrace_command(&event_enable_cmd);
+	if (WARN_ON(ret < 0))
+		return ret;
+	ret = register_ftrace_command(&event_disable_cmd);
+	if (WARN_ON(ret < 0))
+		unregister_ftrace_command(&event_enable_cmd);
+	return ret;
+}
+#else
+static inline int register_event_cmds(void) { return 0; }
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
+/*
+ * The top level array has already had its ftrace_event_file
+ * descriptors created in order to allow for early events to
+ * be recorded. This function is called after the debugfs has been
+ * initialized, and we now have to create the files associated
+ * to the events.
+ */
+static __init void
+__trace_early_add_event_dirs(struct trace_array *tr)
+{
+	struct ftrace_event_file *file;
+	int ret;
+
+
+	list_for_each_entry(file, &tr->events, list) {
+		ret = event_create_dir(tr->event_dir, file,
+				       &ftrace_event_id_fops,
+				       &ftrace_enable_fops,
+				       &ftrace_event_filter_fops,
+				       &ftrace_event_format_fops);
+		if (ret < 0)
+			pr_warning("Could not create directory for event %s\n",
+				   file->event_call->name);
+	}
+}
+
+/*
+ * For early boot up, the top trace array requires to have
+ * a list of events that can be enabled. This must be done before
+ * the filesystem is set up in order to allow events to be traced
+ * early.
+ */
+static __init void
+__trace_early_add_events(struct trace_array *tr)
+{
+	struct ftrace_event_call *call;
+	int ret;
+
+	list_for_each_entry(call, &ftrace_events, list) {
+		/* Early boot up should not have any modules loaded */
+		if (WARN_ON_ONCE(call->mod))
+			continue;
+
+		ret = __trace_early_add_new_event(call, tr);
+		if (ret < 0)
+			pr_warning("Could not create early event %s\n",
+				   call->name);
+	}
+}
+
+/* Remove the event directory structure for a trace directory. */
+static void
+__trace_remove_event_dirs(struct trace_array *tr)
+{
+	struct ftrace_event_file *file, *next;
+
+	list_for_each_entry_safe(file, next, &tr->events, list) {
+		list_del(&file->list);
+		debugfs_remove_recursive(file->dir);
+		remove_subsystem(file->system);
+		kmem_cache_free(file_cachep, file);
+	}
+}
+
+static void
+__add_event_to_tracers(struct ftrace_event_call *call,
+		       struct ftrace_module_file_ops *file_ops)
+{
+	struct trace_array *tr;
+
+	list_for_each_entry(tr, &ftrace_trace_arrays, list) {
+		if (file_ops)
+			__trace_add_new_mod_event(call, tr, file_ops);
+		else
+			__trace_add_new_event(call, tr,
+					      &ftrace_event_id_fops,
+					      &ftrace_enable_fops,
+					      &ftrace_event_filter_fops,
+					      &ftrace_event_format_fops);
+	}
+}
 
 static struct notifier_block trace_module_nb = {
 	.notifier_call = trace_module_notify,
···
 static __init int setup_trace_event(char *str)
 {
 	strlcpy(bootup_event_buf, str, COMMAND_LINE_SIZE);
-	ring_buffer_expanded = 1;
-	tracing_selftest_disabled = 1;
+	ring_buffer_expanded = true;
+	tracing_selftest_disabled = true;
 
 	return 1;
 }
 __setup("trace_event=", setup_trace_event);
 
+/* Expects to have event_mutex held when called */
+static int
+create_event_toplevel_files(struct dentry *parent, struct trace_array *tr)
+{
+	struct dentry *d_events;
+	struct dentry *entry;
+
+	entry = debugfs_create_file("set_event", 0644, parent,
+				    tr, &ftrace_set_event_fops);
+	if (!entry) {
+		pr_warning("Could not create debugfs 'set_event' entry\n");
+		return -ENOMEM;
+	}
+
+	d_events = debugfs_create_dir("events", parent);
+	if (!d_events) {
+		pr_warning("Could not create debugfs 'events' directory\n");
+		return -ENOMEM;
+	}
+
+	/* ring buffer internal formats */
+	trace_create_file("header_page", 0444, d_events,
+			  ring_buffer_print_page_header,
+			  &ftrace_show_header_fops);
+
+	trace_create_file("header_event", 0444, d_events,
+			  ring_buffer_print_entry_header,
+			  &ftrace_show_header_fops);
+
+	trace_create_file("enable", 0644, d_events,
+			  tr, &ftrace_tr_enable_fops);
+
+	tr->event_dir = d_events;
+
+	return 0;
+}
+
+/**
+ * event_trace_add_tracer - add a instance of a trace_array to events
+ * @parent: The parent dentry to place the files/directories for events in
+ * @tr: The trace array associated with these events
+ *
+ * When a new instance is created, it needs to set up its events
+ * directory, as well as other files associated with events. It also
+ * creates the event hierachry in the @parent/events directory.
+ *
+ * Returns 0 on success.
+ */
+int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr)
+{
+	int ret;
+
+	mutex_lock(&event_mutex);
+
+	ret = create_event_toplevel_files(parent, tr);
+	if (ret)
+		goto out_unlock;
+
+	down_write(&trace_event_sem);
+	__trace_add_event_dirs(tr);
+	up_write(&trace_event_sem);
+
+ out_unlock:
+	mutex_unlock(&event_mutex);
+
+	return ret;
+}
+
+/*
+ * The top trace array already had its file descriptors created.
+ * Now the files themselves need to be created.
+ */
+static __init int
+early_event_add_tracer(struct dentry *parent, struct trace_array *tr)
+{
+	int ret;
+
+	mutex_lock(&event_mutex);
+
+	ret = create_event_toplevel_files(parent, tr);
+	if (ret)
+		goto out_unlock;
+
+	down_write(&trace_event_sem);
+	__trace_early_add_event_dirs(tr);
+	up_write(&trace_event_sem);
+
+ out_unlock:
+	mutex_unlock(&event_mutex);
+
+	return ret;
+}
+
+int event_trace_del_tracer(struct trace_array *tr)
+{
+	/* Disable any running events */
+	__ftrace_set_clr_event(tr, NULL, NULL, NULL, 0);
+
+	mutex_lock(&event_mutex);
+
+	down_write(&trace_event_sem);
+	__trace_remove_event_dirs(tr);
+	debugfs_remove_recursive(tr->event_dir);
+	up_write(&trace_event_sem);
+
+	tr->event_dir = NULL;
+
+	mutex_unlock(&event_mutex);
+
+	return 0;
+}
+
+static __init int event_trace_memsetup(void)
+{
+	field_cachep = KMEM_CACHE(ftrace_event_field, SLAB_PANIC);
+	file_cachep = KMEM_CACHE(ftrace_event_file, SLAB_PANIC);
+	return 0;
+}
+
 static __init int event_trace_enable(void)
 {
+	struct trace_array *tr = top_trace_array();
 	struct ftrace_event_call **iter, *call;
 	char *buf = bootup_event_buf;
 	char *token;
···
 			list_add(&call->list, &ftrace_events);
 	}
 
+	/*
+	 * We need the top trace array to have a working set of trace
+	 * points at early init, before the debug files and directories
+	 * are created. Create the file entries now, and attach them
+	 * to the actual file dentries later.
+	 */
+	__trace_early_add_events(tr);
+
 	while (true) {
 		token = strsep(&buf, ",");
 
···
 		if (!*token)
 			continue;
 
-		ret = ftrace_set_clr_event(token, 1);
+		ret = ftrace_set_clr_event(tr, token, 1);
 		if (ret)
 			pr_warn("Failed to enable trace event: %s\n", token);
 	}
 
 	trace_printk_start_comm();
 
+	register_event_cmds();
+
 	return 0;
 }
 
 static __init int event_trace_init(void)
 {
-	struct ftrace_event_call *call;
+	struct trace_array *tr;
 	struct dentry *d_tracer;
 	struct dentry *entry;
-	struct dentry *d_events;
 	int ret;
+
+	tr = top_trace_array();
 
 	d_tracer = tracing_init_dentry();
 	if (!d_tracer)
 		return 0;
 
 	entry = debugfs_create_file("available_events", 0444, d_tracer,
-				    NULL, &ftrace_avail_fops);
+				    tr, &ftrace_avail_fops);
 	if (!entry)
 		pr_warning("Could not create debugfs "
 			   "'available_events' entry\n");
 
-	entry = debugfs_create_file("set_event", 0644, d_tracer,
-				    NULL, &ftrace_set_event_fops);
-	if (!entry)
-		pr_warning("Could not create debugfs "
-			   "'set_event' entry\n");
-
-	d_events = event_trace_events_dir();
-	if (!d_events)
-		return 0;
-
-	/* ring buffer internal formats */
-	trace_create_file("header_page", 0444, d_events,
-			  ring_buffer_print_page_header,
-			  &ftrace_show_header_fops);
-
-	trace_create_file("header_event", 0444, d_events,
-			  ring_buffer_print_entry_header,
-			  &ftrace_show_header_fops);
-
-	trace_create_file("enable", 0644, d_events,
-			  NULL, &ftrace_system_enable_fops);
-
 	if (trace_define_common_fields())
 		pr_warning("tracing: Failed to allocate common fields");
 
-	/*
-	 * Early initialization already enabled ftrace event.
-	 * Now it's only necessary to create the event directory.
-	 */
-	list_for_each_entry(call, &ftrace_events, list) {
-
-		ret = event_create_dir(call, d_events,
-				       &ftrace_event_id_fops,
-				       &ftrace_enable_fops,
-				       &ftrace_event_filter_fops,
-				       &ftrace_event_format_fops);
-		if (ret < 0)
-			event_remove(call);
-	}
+	ret = early_event_add_tracer(d_tracer, tr);
+	if (ret)
+		return ret;
 
 	ret = register_module_notifier(&trace_module_nb);
 	if (ret)
···
 
 	return 0;
 }
+early_initcall(event_trace_memsetup);
 core_initcall(event_trace_enable);
 fs_initcall(event_trace_init);
 
···
  */
 static __init void event_trace_self_tests(void)
 {
+	struct ftrace_subsystem_dir *dir;
+	struct ftrace_event_file *file;
 	struct ftrace_event_call *call;
 	struct event_subsystem *system;
+	struct trace_array *tr;
 	int ret;
+
+	tr = top_trace_array();
 
 	pr_info("Running tests on trace events:\n");
 
-	list_for_each_entry(call, &ftrace_events, list) {
+	list_for_each_entry(file, &tr->events, list) {
+
+		call = file->event_call;
 
 		/* Only test those that have a probe */
 		if (!call->class || !call->class->probe)
···
 		 * If an event is already enabled, someone is using
 		 * it and the self test should not be on.
 		 */
-		if (call->flags & TRACE_EVENT_FL_ENABLED) {
+		if (file->flags & FTRACE_EVENT_FL_ENABLED) {
 			pr_warning("Enabled event during self test!\n");
 			WARN_ON_ONCE(1);
 			continue;
 		}
 
-		ftrace_event_enable_disable(call, 1);
+		ftrace_event_enable_disable(file, 1);
 		event_test_stuff();
-		ftrace_event_enable_disable(call, 0);
+		ftrace_event_enable_disable(file, 0);
 
 		pr_cont("OK\n");
 	}
···
 
 	pr_info("Running tests on trace event systems:\n");
 
-	list_for_each_entry(system, &event_subsystems, list) {
+	list_for_each_entry(dir, &tr->systems, list) {
+
+		system = dir->subsystem;
 
 		/* the ftrace system is special, skip it */
 		if (strcmp(system->name, "ftrace") == 0)
···
 
 		pr_info("Testing event system %s: ", system->name);
 
-		ret = __ftrace_set_clr_event(NULL, system->name, NULL, 1);
+		ret = __ftrace_set_clr_event(tr, NULL, system->name, NULL, 1);
 		if (WARN_ON_ONCE(ret)) {
 			pr_warning("error enabling system %s\n",
 				   system->name);
···
 
 		event_test_stuff();
 
-		ret = __ftrace_set_clr_event(NULL, system->name, NULL, 0);
+		ret = __ftrace_set_clr_event(tr, NULL, system->name, NULL, 0);
 		if (WARN_ON_ONCE(ret)) {
 			pr_warning("error disabling system %s\n",
 				   system->name);
···
 	pr_info("Running tests on all trace events:\n");
 	pr_info("Testing all events: ");
 
-	ret = __ftrace_set_clr_event(NULL, NULL, NULL, 1);
+	ret = __ftrace_set_clr_event(tr, NULL, NULL, NULL, 1);
 	if (WARN_ON_ONCE(ret)) {
 		pr_warning("error enabling all events\n");
 		return;
···
 	event_test_stuff();
 
 	/* reset sysname */
-	ret = __ftrace_set_clr_event(NULL, NULL, NULL, 0);
+	ret = __ftrace_set_clr_event(tr, NULL, NULL, NULL, 0);
 	if (WARN_ON_ONCE(ret)) {
 		pr_warning("error disabling all events\n");
 		return;

kernel/trace/trace_events_filter.c

···
 	mutex_unlock(&event_mutex);
 }
 
-static struct ftrace_event_field *
-__find_event_field(struct list_head *head, char *name)
-{
-	struct ftrace_event_field *field;
-
-	list_for_each_entry(field, head, link) {
-		if (!strcmp(field->name, name))
-			return field;
-	}
-
-	return NULL;
-}
-
-static struct ftrace_event_field *
-find_event_field(struct ftrace_event_call *call, char *name)
-{
-	struct ftrace_event_field *field;
-	struct list_head *head;
-
-	field = __find_event_field(&ftrace_common_fields, name);
-	if (field)
-		return field;
-
-	head = trace_get_fields(call);
-	return __find_event_field(head, name);
-}
-
 static int __alloc_pred_stack(struct pred_stack *stack, int n_preds)
 {
 	stack->preds = kcalloc(n_preds + 1, sizeof(*stack->preds), GFP_KERNEL);
···
 		return NULL;
 	}
 
-	field = find_event_field(call, operand1);
+	field = trace_find_event_field(call, operand1);
 	if (!field) {
 		parse_error(ps, FILT_ERR_FIELD_NOT_FOUND, 0);
 		return NULL;
···
 	return err;
 }
 
-int apply_subsystem_event_filter(struct event_subsystem *system,
+int apply_subsystem_event_filter(struct ftrace_subsystem_dir *dir,
 				 char *filter_string)
 {
+	struct event_subsystem *system = dir->subsystem;
 	struct event_filter *filter;
 	int err = 0;
 
 	mutex_lock(&event_mutex);
 
 	/* Make sure the system still has events */
-	if (!system->nr_events) {
+	if (!dir->nr_events) {
 		err = -ENODEV;
 		goto out_unlock;
 	}

kernel/trace/trace_export.c

···
 
 #undef FTRACE_ENTRY
 #define FTRACE_ENTRY(name, struct_name, id, tstruct, print, filter)	\
-int									\
+static int __init							\
 ftrace_define_fields_##name(struct ftrace_event_call *event_call)	\
 {									\
 	struct struct_name field;					\
···
 #define FTRACE_ENTRY_REG(call, struct_name, etype, tstruct, print, filter,\
 			 regfn)						\
 									\
-struct ftrace_event_class event_class_ftrace_##call = {			\
+struct ftrace_event_class __refdata event_class_ftrace_##call = {	\
 	.system			= __stringify(TRACE_SYSTEM),		\
 	.define_fields		= ftrace_define_fields_##call,		\
 	.fields			= LIST_HEAD_INIT(event_class_ftrace_##call.fields),\

kernel/trace/trace_functions.c

···
 static int function_trace_init(struct trace_array *tr)
 {
 	func_trace = tr;
-	tr->cpu = get_cpu();
+	tr->trace_buffer.cpu = get_cpu();
 	put_cpu();
 
 	tracing_start_cmdline_record();
···
 
 static void function_trace_start(struct trace_array *tr)
 {
-	tracing_reset_online_cpus(tr);
+	tracing_reset_online_cpus(&tr->trace_buffer);
 }
 
 /* Our option */
···
 		goto out;
 
 	cpu = smp_processor_id();
-	data = tr->data[cpu];
+	data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 	if (!atomic_read(&data->disabled)) {
 		local_save_flags(flags);
 		trace_function(tr, ip, parent_ip, flags, pc);
···
 	 */
 	local_irq_save(flags);
 	cpu = raw_smp_processor_id();
-	data = tr->data[cpu];
+	data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 	disabled = atomic_inc_return(&data->disabled);
 
 	if (likely(disabled == 1)) {
···
 };
 
 #ifdef CONFIG_DYNAMIC_FTRACE
-static void
-ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
+static int update_count(void **data)
 {
-	long *count = (long *)data;
-
-	if (tracing_is_on())
-		return;
+	unsigned long *count = (long *)data;
 
 	if (!*count)
-		return;
+		return 0;
 
 	if (*count != -1)
 		(*count)--;
+
+	return 1;
+}
+
+static void
+ftrace_traceon_count(unsigned long ip, unsigned long parent_ip, void **data)
+{
+	if (tracing_is_on())
+		return;
+
+	if (update_count(data))
+		tracing_on();
+}
+
+static void
+ftrace_traceoff_count(unsigned long ip, unsigned long parent_ip, void **data)
+{
+	if (!tracing_is_on())
+		return;
+
+	if (update_count(data))
+		tracing_off();
+}
+
+static void
+ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
+{
+	if (tracing_is_on())
+		return;
 
 	tracing_on();
 }
···
 static void
 ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
 {
-	long *count = (long *)data;
-
 	if (!tracing_is_on())
 		return;
-
-	if (!*count)
-		return;
-
-	if (*count != -1)
-		(*count)--;
 
 	tracing_off();
 }
 
+/*
+ * Skip 4:
+ *   ftrace_stacktrace()
+ *   function_trace_probe_call()
+ *   ftrace_ops_list_func()
+ *   ftrace_call()
+ */
+#define STACK_SKIP 4
+
+static void
+ftrace_stacktrace(unsigned long ip, unsigned long parent_ip, void **data)
+{
+	trace_dump_stack(STACK_SKIP);
+}
+
+static void
+ftrace_stacktrace_count(unsigned long ip, unsigned long parent_ip, void **data)
+{
+	if (!tracing_is_on())
+		return;
+
+	if (update_count(data))
+		trace_dump_stack(STACK_SKIP);
+}
+
 static int
-ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
-			 struct ftrace_probe_ops *ops, void *data);
-
-static struct ftrace_probe_ops traceon_probe_ops = {
-	.func			= ftrace_traceon,
-	.print			= ftrace_trace_onoff_print,
-};
-
-static struct ftrace_probe_ops traceoff_probe_ops = {
-	.func			= ftrace_traceoff,
-	.print			= ftrace_trace_onoff_print,
-};
-
-static int
-ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
-			 struct ftrace_probe_ops *ops, void *data)
+ftrace_probe_print(const char *name, struct seq_file *m,
+		   unsigned long ip, void *data)
 {
 	long count = (long)data;
 
-	seq_printf(m, "%ps:", (void *)ip);
-
-	if (ops == &traceon_probe_ops)
-		seq_printf(m, "traceon");
-	else
-		seq_printf(m, "traceoff");
+	seq_printf(m, "%ps:%s", (void *)ip, name);
 
 	if (count == -1)
 		seq_printf(m, ":unlimited\n");
···
 }
 
 static int
-ftrace_trace_onoff_unreg(char *glob, char *cmd, char *param)
+ftrace_traceon_print(struct seq_file *m, unsigned long ip,
+			 struct ftrace_probe_ops *ops, void *data)
 {
-	struct ftrace_probe_ops *ops;
-
-	/* we register both traceon and traceoff to this callback */
-	if (strcmp(cmd, "traceon") == 0)
-		ops = &traceon_probe_ops;
-	else
-		ops = &traceoff_probe_ops;
-
-	unregister_ftrace_function_probe_func(glob, ops);
-
-	return 0;
+	return ftrace_probe_print("traceon", m, ip, data);
 }
 
 static int
-ftrace_trace_onoff_callback(struct ftrace_hash *hash,
-			    char *glob, char *cmd, char *param, int enable)
+ftrace_traceoff_print(struct seq_file *m, unsigned long ip,
+			 struct ftrace_probe_ops *ops, void *data)
 {
-	struct ftrace_probe_ops *ops;
+	return ftrace_probe_print("traceoff", m, ip, data);
+}
+
+static int
+ftrace_stacktrace_print(struct seq_file *m, unsigned long ip,
+			struct ftrace_probe_ops *ops, void *data)
+{
+	return ftrace_probe_print("stacktrace", m, ip, data);
+}
+
+static struct ftrace_probe_ops traceon_count_probe_ops = {
+	.func			= ftrace_traceon_count,
+	.print			= ftrace_traceon_print,
+};
+
+static struct ftrace_probe_ops traceoff_count_probe_ops = {
+	.func			= ftrace_traceoff_count,
+	.print			= ftrace_traceoff_print,
+};
+
+static struct ftrace_probe_ops stacktrace_count_probe_ops = {
+	.func			= ftrace_stacktrace_count,
+	.print			= ftrace_stacktrace_print,
+};
+
+static struct ftrace_probe_ops traceon_probe_ops = {
+	.func			= ftrace_traceon,
+	.print			= ftrace_traceon_print,
+};
+
+static struct ftrace_probe_ops traceoff_probe_ops = {
+	.func			= ftrace_traceoff,
+	.print			= ftrace_traceoff_print,
+};
+
+static struct ftrace_probe_ops stacktrace_probe_ops = {
+	.func			= ftrace_stacktrace,
+	.print			= ftrace_stacktrace_print,
+};
+
+static int
+ftrace_trace_probe_callback(struct ftrace_probe_ops *ops,
+			    struct ftrace_hash *hash, char *glob,
+			    char *cmd, char *param, int enable)
+{
 	void *count = (void *)-1;
 	char *number;
 	int ret;
···
 	if (!enable)
 		return -EINVAL;
 
-	if (glob[0] == '!')
-		return ftrace_trace_onoff_unreg(glob+1, cmd, param);
-
-	/* we register both traceon and traceoff to this callback */
-	if (strcmp(cmd, "traceon") == 0)
-		ops = &traceon_probe_ops;
-	else
-		ops = &traceoff_probe_ops;
+	if (glob[0] == '!') {
+		unregister_ftrace_function_probe_func(glob+1, ops);
+		return 0;
+	}
 
 	if (!param)
 		goto out_reg;
···
 	return ret < 0 ? ret : 0;
 }
 
+static int
+ftrace_trace_onoff_callback(struct ftrace_hash *hash,
+			    char *glob, char *cmd, char *param, int enable)
+{
+	struct ftrace_probe_ops *ops;
+
+	/* we register both traceon and traceoff to this callback */
+	if (strcmp(cmd, "traceon") == 0)
+		ops = param ? &traceon_count_probe_ops : &traceon_probe_ops;
+	else
+		ops = param ? &traceoff_count_probe_ops : &traceoff_probe_ops;
+
+	return ftrace_trace_probe_callback(ops, hash, glob, cmd,
+					   param, enable);
+}
+
+static int
+ftrace_stacktrace_callback(struct ftrace_hash *hash,
+			   char *glob, char *cmd, char *param, int enable)
+{
+	struct ftrace_probe_ops *ops;
+
+	ops = param ? &stacktrace_count_probe_ops : &stacktrace_probe_ops;
+
+	return ftrace_trace_probe_callback(ops, hash, glob, cmd,
+					   param, enable);
+}
+
 static struct ftrace_func_command ftrace_traceon_cmd = {
 	.name			= "traceon",
 	.func			= ftrace_trace_onoff_callback,
···
 static struct ftrace_func_command ftrace_traceoff_cmd = {
 	.name			= "traceoff",
 	.func			= ftrace_trace_onoff_callback,
+};
+
+static struct ftrace_func_command ftrace_stacktrace_cmd = {
+	.name			= "stacktrace",
+	.func			= ftrace_stacktrace_callback,
 };
 
 static int __init init_func_cmd_traceon(void)
···
 	ret = register_ftrace_command(&ftrace_traceon_cmd);
 	if (ret)
 		unregister_ftrace_command(&ftrace_traceoff_cmd);
+
+	ret = register_ftrace_command(&ftrace_stacktrace_cmd);
+	if (ret) {
+		unregister_ftrace_command(&ftrace_traceoff_cmd);
+		unregister_ftrace_command(&ftrace_traceon_cmd);
+	}
 	return ret;
 }
 #else

kernel/trace/trace_functions_graph.c

···
 {
 	struct ftrace_event_call *call = &event_funcgraph_entry;
 	struct ring_buffer_event *event;
-	struct ring_buffer *buffer = tr->buffer;
+	struct ring_buffer *buffer = tr->trace_buffer.buffer;
 	struct ftrace_graph_ent_entry *entry;
 
 	if (unlikely(__this_cpu_read(ftrace_cpu_disabled)))
···
 
 	local_irq_save(flags);
 	cpu = raw_smp_processor_id();
-	data = tr->data[cpu];
+	data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 	disabled = atomic_inc_return(&data->disabled);
 	if (likely(disabled == 1)) {
 		pc = preempt_count();
···
 {
 	struct ftrace_event_call *call = &event_funcgraph_exit;
 	struct ring_buffer_event *event;
-	struct ring_buffer *buffer = tr->buffer;
+	struct ring_buffer *buffer = tr->trace_buffer.buffer;
 	struct ftrace_graph_ret_entry *entry;
 
 	if (unlikely(__this_cpu_read(ftrace_cpu_disabled)))
···
 
 	local_irq_save(flags);
 	cpu = raw_smp_processor_id();
-	data = tr->data[cpu];
+	data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 	disabled = atomic_inc_return(&data->disabled);
 	if (likely(disabled == 1)) {
 		pc = preempt_count();
···
 			 * We need to consume the current entry to see
 			 * the next one.
 			 */
-			ring_buffer_consume(iter->tr->buffer, iter->cpu,
+			ring_buffer_consume(iter->trace_buffer->buffer, iter->cpu,
 					    NULL, NULL);
-			event = ring_buffer_peek(iter->tr->buffer, iter->cpu,
+			event = ring_buffer_peek(iter->trace_buffer->buffer, iter->cpu,
 						 NULL, NULL);
 		}
 

kernel/trace/trace_irqsoff.c

···
 static int trace_type __read_mostly;
 
 static int save_flags;
+static bool function_enabled;
 
 static void stop_irqsoff_tracer(struct trace_array *tr, int graph);
 static int start_irqsoff_tracer(struct trace_array *tr, int graph);
···
 	if (!irqs_disabled_flags(*flags))
 		return 0;
 
-	*data = tr->data[cpu];
+	*data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 	disabled = atomic_inc_return(&(*data)->disabled);
 
 	if (likely(disabled == 1))
···
 		per_cpu(tracing_cpu, cpu) = 0;
 
 	tracing_max_latency = 0;
-	tracing_reset_online_cpus(irqsoff_trace);
+	tracing_reset_online_cpus(&irqsoff_trace->trace_buffer);
 
 	return start_irqsoff_tracer(irqsoff_trace, set);
 }
···
 	if (per_cpu(tracing_cpu, cpu))
 		return;
 
-	data = tr->data[cpu];
+	data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 
 	if (unlikely(!data) || atomic_read(&data->disabled))
 		return;
···
 	if (!tracer_enabled)
 		return;
 
-	data = tr->data[cpu];
+	data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 
 	if (unlikely(!data) ||
 	    !data->critical_start || atomic_read(&data->disabled))
···
 }
 #endif /* CONFIG_PREEMPT_TRACER */
 
-static int start_irqsoff_tracer(struct trace_array *tr, int graph)
+static int register_irqsoff_function(int graph, int set)
 {
-	int ret = 0;
+	int ret;
 
-	if (!graph)
-		ret = register_ftrace_function(&trace_ops);
-	else
+	/* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
+	if (function_enabled || (!set && !(trace_flags & TRACE_ITER_FUNCTION)))
+		return 0;
+
+	if (graph)
 		ret = register_ftrace_graph(&irqsoff_graph_return,
 					    &irqsoff_graph_entry);
+	else
+		ret = register_ftrace_function(&trace_ops);
+
+	if (!ret)
+		function_enabled = true;
+
+	return ret;
+}
+
+static void unregister_irqsoff_function(int graph)
+{
+	if (!function_enabled)
+		return;
+
+	if (graph)
+		unregister_ftrace_graph();
+	else
+		unregister_ftrace_function(&trace_ops);
+
+	function_enabled = false;
+}
+
+static void irqsoff_function_set(int set)
+{
+	if (set)
+		register_irqsoff_function(is_graph(), 1);
+	else
+		unregister_irqsoff_function(is_graph());
+}
+
+static int irqsoff_flag_changed(struct tracer *tracer, u32 mask, int set)
+{
+	if (mask & TRACE_ITER_FUNCTION)
+		irqsoff_function_set(set);
+
+	return trace_keep_overwrite(tracer, mask, set);
+}
+
+static int start_irqsoff_tracer(struct trace_array *tr, int graph)
+{
+	int ret;
+
+	ret = register_irqsoff_function(graph, 0);
 
 	if (!ret && tracing_is_enabled())
 		tracer_enabled = 1;
···
 {
 	tracer_enabled = 0;
 
-	if (!graph)
-		unregister_ftrace_function(&trace_ops);
-	else
-		unregister_ftrace_graph();
+	unregister_irqsoff_function(graph);
 }
 
 static void __irqsoff_tracer_init(struct trace_array *tr)
···
 	save_flags = trace_flags;
 
 	/* non overwrite screws up the latency tracers */
-	set_tracer_flag(TRACE_ITER_OVERWRITE, 1);
-	set_tracer_flag(TRACE_ITER_LATENCY_FMT, 1);
+	set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
+	set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
 
 	tracing_max_latency = 0;
 	irqsoff_trace = tr;
 	/* make sure that the tracer is visible */
 	smp_wmb();
-	tracing_reset_online_cpus(tr);
+	tracing_reset_online_cpus(&tr->trace_buffer);
 
 	if (start_irqsoff_tracer(tr, is_graph()))
 		printk(KERN_ERR "failed to start irqsoff tracer\n");
···
 
 	stop_irqsoff_tracer(tr, is_graph());
 
-	set_tracer_flag(TRACE_ITER_LATENCY_FMT, lat_flag);
-	set_tracer_flag(TRACE_ITER_OVERWRITE, overwrite_flag);
+	set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
+	set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
 }
 
 static void irqsoff_tracer_start(struct trace_array *tr)
···
 	.print_line     = irqsoff_print_line,
 	.flags		= &tracer_flags,
 	.set_flag	= irqsoff_set_flag,
-	.flag_changed	= trace_keep_overwrite,
+	.flag_changed	= irqsoff_flag_changed,
 #ifdef CONFIG_FTRACE_SELFTEST
 	.selftest    = trace_selftest_startup_irqsoff,
 #endif
···
 	.print_line     = irqsoff_print_line,
 	.flags		= &tracer_flags,
 	.set_flag	= irqsoff_set_flag,
-	.flag_changed	= trace_keep_overwrite,
+	.flag_changed	= irqsoff_flag_changed,
 #ifdef CONFIG_FTRACE_SELFTEST
 	.selftest    = trace_selftest_startup_preemptoff,
 #endif
···
 	.print_line     = irqsoff_print_line,
 	.flags		= &tracer_flags,
 	.set_flag	= irqsoff_set_flag,
-	.flag_changed	= trace_keep_overwrite,
+	.flag_changed	= irqsoff_flag_changed,
 #ifdef CONFIG_FTRACE_SELFTEST
 	.selftest    = trace_selftest_startup_preemptirqsoff,
 #endif

kernel/trace/trace_kdb.c

···
 	trace_init_global_iter(&iter);
 
 	for_each_tracing_cpu(cpu) {
-		atomic_inc(&iter.tr->data[cpu]->disabled);
+		atomic_inc(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled);
 	}
 
 	old_userobj = trace_flags;
···
 	iter.iter_flags |= TRACE_FILE_LAT_FMT;
 	iter.pos = -1;
 
-	if (cpu_file == TRACE_PIPE_ALL_CPU) {
+	if (cpu_file == RING_BUFFER_ALL_CPUS) {
 		for_each_tracing_cpu(cpu) {
 			iter.buffer_iter[cpu] =
-			ring_buffer_read_prepare(iter.tr->buffer, cpu);
+			ring_buffer_read_prepare(iter.trace_buffer->buffer, cpu);
 			ring_buffer_read_start(iter.buffer_iter[cpu]);
 			tracing_iter_reset(&iter, cpu);
 		}
 	} else {
 		iter.cpu_file = cpu_file;
 		iter.buffer_iter[cpu_file] =
-			ring_buffer_read_prepare(iter.tr->buffer, cpu_file);
+			ring_buffer_read_prepare(iter.trace_buffer->buffer, cpu_file);
 		ring_buffer_read_start(iter.buffer_iter[cpu_file]);
 		tracing_iter_reset(&iter, cpu_file);
 	}
···
 	trace_flags = old_userobj;
 
 	for_each_tracing_cpu(cpu) {
-		atomic_dec(&iter.tr->data[cpu]->disabled);
+		atomic_dec(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled);
 	}
 
 	for_each_tracing_cpu(cpu)
···
 		    !cpu_online(cpu_file))
 			return KDB_BADINT;
 	} else {
-		cpu_file = TRACE_PIPE_ALL_CPU;
+		cpu_file = RING_BUFFER_ALL_CPUS;
 	}
 
 	kdb_trap_printk++;

kernel/trace/trace_mmiotrace.c

···
 	overrun_detected = false;
 	prev_overruns = 0;
 
-	tracing_reset_online_cpus(tr);
+	tracing_reset_online_cpus(&tr->trace_buffer);
 }
 
 static int mmio_trace_init(struct trace_array *tr)
···
 static unsigned long count_overruns(struct trace_iterator *iter)
 {
 	unsigned long cnt = atomic_xchg(&dropped_count, 0);
-	unsigned long over = ring_buffer_overruns(iter->tr->buffer);
+	unsigned long over = ring_buffer_overruns(iter->trace_buffer->buffer);
 
 	if (over > prev_overruns)
 		cnt += over - prev_overruns;
···
 				struct mmiotrace_rw *rw)
 {
 	struct ftrace_event_call *call = &event_mmiotrace_rw;
-	struct ring_buffer *buffer = tr->buffer;
+	struct ring_buffer *buffer = tr->trace_buffer.buffer;
 	struct ring_buffer_event *event;
 	struct trace_mmiotrace_rw *entry;
 	int pc = preempt_count();
···
 void mmio_trace_rw(struct mmiotrace_rw *rw)
 {
 	struct trace_array *tr = mmio_trace_array;
-	struct trace_array_cpu *data = tr->data[smp_processor_id()];
+	struct trace_array_cpu *data = per_cpu_ptr(tr->trace_buffer.data, smp_processor_id());
 	__trace_mmiotrace_rw(tr, data, rw);
 }
 
···
 				struct mmiotrace_map *map)
 {
 	struct ftrace_event_call *call = &event_mmiotrace_map;
-	struct ring_buffer *buffer = tr->buffer;
+	struct ring_buffer *buffer = tr->trace_buffer.buffer;
 	struct ring_buffer_event *event;
 	struct trace_mmiotrace_map *entry;
 	int pc = preempt_count();
···
 	struct trace_array_cpu *data;
 
 	preempt_disable();
-	data = tr->data[smp_processor_id()];
+	data = per_cpu_ptr(tr->trace_buffer.data, smp_processor_id());
 	__trace_mmiotrace_map(tr, data, map);
 	preempt_enable();
 }

kernel/trace/trace_output.c

···
 /* must be a power of 2 */
 #define EVENT_HASHSIZE	128
 
-DECLARE_RWSEM(trace_event_mutex);
+DECLARE_RWSEM(trace_event_sem);
 
 static struct hlist_head event_hash[EVENT_HASHSIZE] __read_mostly;
 
···
 		trace_seq_init(s);
 
 	return ret;
+}
+
+enum print_line_t trace_print_bputs_msg_only(struct trace_iterator *iter)
+{
+	struct trace_seq *s = &iter->seq;
+	struct trace_entry *entry = iter->ent;
+	struct bputs_entry *field;
+	int ret;
+
+	trace_assign_type(field, entry);
+
+	ret = trace_seq_puts(s, field->str);
+	if (!ret)
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	return TRACE_TYPE_HANDLED;
 }
 
 enum print_line_t trace_print_bprintk_msg_only(struct trace_iterator *iter)
···
 }
 EXPORT_SYMBOL(ftrace_print_hex_seq);
 
+int ftrace_raw_output_prep(struct trace_iterator *iter,
+			   struct trace_event *trace_event)
+{
+	struct ftrace_event_call *event;
+	struct trace_seq *s = &iter->seq;
+	struct trace_seq *p = &iter->tmp_seq;
+	struct trace_entry *entry;
+	int ret;
+
+	event = container_of(trace_event, struct ftrace_event_call, event);
+	entry = iter->ent;
+
+	if (entry->type != event->event.type) {
+		WARN_ON_ONCE(1);
+		return TRACE_TYPE_UNHANDLED;
+	}
+
+	trace_seq_init(p);
+	ret = trace_seq_printf(s, "%s: ", event->name);
+	if (!ret)
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	return 0;
+}
+EXPORT_SYMBOL(ftrace_raw_output_prep);
+
 #ifdef CONFIG_KRETPROBES
 static inline const char *kretprobed(const char *name)
 {
···
 {
 	unsigned long verbose = trace_flags & TRACE_ITER_VERBOSE;
 	unsigned long in_ns = iter->iter_flags & TRACE_FILE_TIME_IN_NS;
-	unsigned long long abs_ts = iter->ts - iter->tr->time_start;
+	unsigned long long abs_ts = iter->ts - iter->trace_buffer->time_start;
 	unsigned long long rel_ts = next_ts - iter->ts;
 	struct trace_seq *s = &iter->seq;
 
···
 
 void trace_event_read_lock(void)
 {
-	down_read(&trace_event_mutex);
+	down_read(&trace_event_sem);
 }
 
 void trace_event_read_unlock(void)
 {
-	up_read(&trace_event_mutex);
+	up_read(&trace_event_sem);
 }
 
 /**
···
 	unsigned key;
 	int ret = 0;
 
-	down_write(&trace_event_mutex);
+	down_write(&trace_event_sem);
 
 	if (WARN_ON(!event))
 		goto out;
···
 
 	ret = event->type;
  out:
-	up_write(&trace_event_mutex);
+	up_write(&trace_event_sem);
 
 	return ret;
 }
 EXPORT_SYMBOL_GPL(register_ftrace_event);
 
 /*
- * Used by module code with the trace_event_mutex held for write.
+ * Used by module code with the trace_event_sem held for write.
  */
 int __unregister_ftrace_event(struct trace_event *event)
 {
···
  */
 int unregister_ftrace_event(struct trace_event *event)
 {
-	down_write(&trace_event_mutex);
+	down_write(&trace_event_sem);
 	__unregister_ftrace_event(event);
-	up_write(&trace_event_mutex);
+	up_write(&trace_event_sem);
 
 	return 0;
 }
···
 	.funcs		= &trace_user_stack_funcs,
 };
 
+/* TRACE_BPUTS */
+static enum print_line_t
+trace_bputs_print(struct trace_iterator *iter, int flags,
+		   struct trace_event *event)
+{
+	struct trace_entry *entry = iter->ent;
+	struct trace_seq *s = &iter->seq;
+	struct bputs_entry *field;
+
+	trace_assign_type(field, entry);
+
+	if (!seq_print_ip_sym(s, field->ip, flags))
+		goto partial;
+
+	if (!trace_seq_puts(s, ": "))
+		goto partial;
+
+	if (!trace_seq_puts(s, field->str))
+		goto partial;
+
+	return TRACE_TYPE_HANDLED;
+
+ partial:
+	return TRACE_TYPE_PARTIAL_LINE;
+}
+
+
+static enum print_line_t
+trace_bputs_raw(struct trace_iterator *iter, int flags,
+		struct trace_event *event)
+{
+	struct bputs_entry *field;
+	struct trace_seq *s = &iter->seq;
+
+	trace_assign_type(field, iter->ent);
+
+	if (!trace_seq_printf(s, ": %lx : ", field->ip))
+		goto partial;
+
+	if (!trace_seq_puts(s, field->str))
+		goto partial;
+
+	return TRACE_TYPE_HANDLED;
+
+ partial:
+	return TRACE_TYPE_PARTIAL_LINE;
+}
+
+static struct trace_event_functions trace_bputs_funcs = {
+	.trace		= trace_bputs_print,
+	.raw		= trace_bputs_raw,
+};
+
+static struct trace_event trace_bputs_event = {
+	.type		= TRACE_BPUTS,
+	.funcs		= &trace_bputs_funcs,
+};
+
 /* TRACE_BPRINT */
 static enum print_line_t
 trace_bprint_print(struct trace_iterator *iter, int flags,
···
 	&trace_wake_event,
 	&trace_stack_event,
 	&trace_user_stack_event,
+	&trace_bputs_event,
 	&trace_bprint_event,
 	&trace_print_event,
 	NULL

kernel/trace/trace_output.h

···
 #include "trace.h"
 
 extern enum print_line_t
+trace_print_bputs_msg_only(struct trace_iterator *iter);
+extern enum print_line_t
 trace_print_bprintk_msg_only(struct trace_iterator *iter);
 extern enum print_line_t
 trace_print_printk_msg_only(struct trace_iterator *iter);
···
 
 /* used by module unregistering */
 extern int __unregister_ftrace_event(struct trace_event *event);
-extern struct rw_semaphore trace_event_mutex;
+extern struct rw_semaphore trace_event_sem;
 
 #define MAX_MEMHEX_BYTES	8
 #define HEX_CHARS		(MAX_MEMHEX_BYTES*2 + 1)

kernel/trace/trace_sched_switch.c

···
 			   unsigned long flags, int pc)
 {
 	struct ftrace_event_call *call = &event_context_switch;
-	struct ring_buffer *buffer = tr->buffer;
+	struct ring_buffer *buffer = tr->trace_buffer.buffer;
 	struct ring_buffer_event *event;
 	struct ctx_switch_entry *entry;
 
···
 	pc = preempt_count();
 	local_irq_save(flags);
 	cpu = raw_smp_processor_id();
-	data = ctx_trace->data[cpu];
+	data = per_cpu_ptr(ctx_trace->trace_buffer.data, cpu);
 
 	if (likely(!atomic_read(&data->disabled)))
 		tracing_sched_switch_trace(ctx_trace, prev, next, flags, pc);
···
 	struct ftrace_event_call *call = &event_wakeup;
 	struct ring_buffer_event *event;
 	struct ctx_switch_entry *entry;
-	struct ring_buffer *buffer = tr->buffer;
+	struct ring_buffer *buffer = tr->trace_buffer.buffer;
 
 	event = trace_buffer_lock_reserve(buffer, TRACE_WAKE,
 					  sizeof(*entry), flags, pc);
···
 	pc = preempt_count();
 	local_irq_save(flags);
 	cpu = raw_smp_processor_id();
-	data = ctx_trace->data[cpu];
+	data = per_cpu_ptr(ctx_trace->trace_buffer.data, cpu);
 
 	if (likely(!atomic_read(&data->disabled)))
 		tracing_sched_wakeup_trace(ctx_trace, wakee, current,

kernel/trace/trace_sched_wakeup.c

···
 static void wakeup_graph_return(struct ftrace_graph_ret *trace);
 
 static int save_flags;
+static bool function_enabled;
 
 #define TRACE_DISPLAY_GRAPH     1
 
···
 	if (cpu != wakeup_current_cpu)
 		goto out_enable;
 
-	*data = tr->data[cpu];
+	*data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 	disabled = atomic_inc_return(&(*data)->disabled);
 	if (unlikely(disabled != 1))
 		goto out;
···
 };
 #endif /* CONFIG_FUNCTION_TRACER */
 
+static int register_wakeup_function(int graph, int set)
+{
+	int ret;
+
+	/* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
+	if (function_enabled || (!set && !(trace_flags & TRACE_ITER_FUNCTION)))
+		return 0;
+
+	if (graph)
+		ret = register_ftrace_graph(&wakeup_graph_return,
+					    &wakeup_graph_entry);
+	else
+		ret = register_ftrace_function(&trace_ops);
+
+	if (!ret)
+		function_enabled = true;
+
+	return ret;
+}
+
+static void unregister_wakeup_function(int graph)
+{
+	if (!function_enabled)
+		return;
+
+	if (graph)
+		unregister_ftrace_graph();
+	else
+		unregister_ftrace_function(&trace_ops);
+
+	function_enabled = false;
+}
+
+static void wakeup_function_set(int set)
+{
+	if (set)
+		register_wakeup_function(is_graph(), 1);
+	else
+		unregister_wakeup_function(is_graph());
+}
+
+static int wakeup_flag_changed(struct tracer *tracer, u32 mask, int set)
+{
+	if (mask & TRACE_ITER_FUNCTION)
+		wakeup_function_set(set);
+
+	return trace_keep_overwrite(tracer, mask, set);
+}
+
 static int start_func_tracer(int graph)
 {
 	int ret;
 
-	if (!graph)
-		ret = register_ftrace_function(&trace_ops);
-	else
-		ret = register_ftrace_graph(&wakeup_graph_return,
-					    &wakeup_graph_entry);
+	ret = register_wakeup_function(graph, 0);
 
 	if (!ret && tracing_is_enabled())
 		tracer_enabled = 1;
···
 {
 	tracer_enabled = 0;
 
-	if (!graph)
-		unregister_ftrace_function(&trace_ops);
-	else
-		unregister_ftrace_graph();
+	unregister_wakeup_function(graph);
 }
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
···
 
 	/* disable local data, not wakeup_cpu data */
 	cpu = raw_smp_processor_id();
-	disabled = atomic_inc_return(&wakeup_trace->data[cpu]->disabled);
+	disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
 	if (likely(disabled != 1))
 		goto out;
 
···
 		goto out_unlock;
 
 	/* The task we are waiting for is waking up */
-	data = wakeup_trace->data[wakeup_cpu];
+	data = per_cpu_ptr(wakeup_trace->trace_buffer.data, wakeup_cpu);
 
 	__trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
 	tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
···
 	arch_spin_unlock(&wakeup_lock);
 	local_irq_restore(flags);
 out:
-	atomic_dec(&wakeup_trace->data[cpu]->disabled);
+	atomic_dec(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
 }
 
 static void __wakeup_reset(struct trace_array *tr)
···
 {
 	unsigned long flags;
 
-	tracing_reset_online_cpus(tr);
+	tracing_reset_online_cpus(&tr->trace_buffer);
 
 	local_irq_save(flags);
 	arch_spin_lock(&wakeup_lock);
···
 		return;
 
 	pc = preempt_count();
-	disabled = atomic_inc_return(&wakeup_trace->data[cpu]->disabled);
+	disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
 	if (unlikely(disabled != 1))
 		goto out;
 
···
 
 	local_save_flags(flags);
 
-	data = wakeup_trace->data[wakeup_cpu];
+	data = per_cpu_ptr(wakeup_trace->trace_buffer.data, wakeup_cpu);
 	data->preempt_timestamp = ftrace_now(cpu);
 	tracing_sched_wakeup_trace(wakeup_trace, p, current, flags, pc);
 
···
 out_locked:
 	arch_spin_unlock(&wakeup_lock);
 out:
-	atomic_dec(&wakeup_trace->data[cpu]->disabled);
+	atomic_dec(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
 }
 
 static void start_wakeup_tracer(struct trace_array *tr)
···
 	save_flags = trace_flags;
 
 	/* non overwrite screws up the latency tracers */
-	set_tracer_flag(TRACE_ITER_OVERWRITE, 1);
-	set_tracer_flag(TRACE_ITER_LATENCY_FMT, 1);
+	set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
+	set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
 
 	tracing_max_latency = 0;
 	wakeup_trace = tr;
···
 	/* make sure we put back any tasks we are tracing */
 	wakeup_reset(tr);
 
-	set_tracer_flag(TRACE_ITER_LATENCY_FMT, lat_flag);
-	set_tracer_flag(TRACE_ITER_OVERWRITE, overwrite_flag);
+	set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
+	set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
 }
 
 static void wakeup_tracer_start(struct trace_array *tr)
···
 	.print_line	= wakeup_print_line,
 	.flags		= &tracer_flags,
 	.set_flag	= wakeup_set_flag,
-	.flag_changed	= trace_keep_overwrite,
+	.flag_changed	= wakeup_flag_changed,
 #ifdef CONFIG_FTRACE_SELFTEST
 	.selftest    = trace_selftest_startup_wakeup,
 #endif
···
 	.print_line	= wakeup_print_line,
 	.flags		= &tracer_flags,
 	.set_flag	= wakeup_set_flag,
-	.flag_changed	= trace_keep_overwrite,
+	.flag_changed	= wakeup_flag_changed,
 #ifdef CONFIG_FTRACE_SELFTEST
 	.selftest    = trace_selftest_startup_wakeup,
 #endif

kernel/trace/trace_selftest.c

···
 	return 0;
 }
 
-static int trace_test_buffer_cpu(struct trace_array *tr, int cpu)
+static int trace_test_buffer_cpu(struct trace_buffer *buf, int cpu)
 {
 	struct ring_buffer_event *event;
 	struct trace_entry *entry;
 	unsigned int loops = 0;
 
-	while ((event = ring_buffer_consume(tr->buffer, cpu, NULL, NULL))) {
+	while ((event = ring_buffer_consume(buf->buffer, cpu, NULL, NULL))) {
 		entry = ring_buffer_event_data(event);
 
 		/*
···
  * Test the trace buffer to see if all the elements
  * are still sane.
  */
-static int trace_test_buffer(struct trace_array *tr, unsigned long *count)
+static int trace_test_buffer(struct trace_buffer *buf, unsigned long *count)
 {
 	unsigned long flags, cnt = 0;
 	int cpu, ret = 0;
···
 	local_irq_save(flags);
 	arch_spin_lock(&ftrace_max_lock);
 
-	cnt = ring_buffer_entries(tr->buffer);
+	cnt = ring_buffer_entries(buf->buffer);
 
 	/*
 	 * The trace_test_buffer_cpu runs a while loop to consume all data.
···
 	 */
 	tracing_off();
 	for_each_possible_cpu(cpu) {
-		ret = trace_test_buffer_cpu(tr, cpu);
+		ret = trace_test_buffer_cpu(buf, cpu);
 		if (ret)
 			break;
 	}
···
 	msleep(100);
 
 	/* we should have nothing in the buffer */
-	ret = trace_test_buffer(tr, &count);
+	ret = trace_test_buffer(&tr->trace_buffer, &count);
 	if (ret)
 		goto out;
 
···
 	ftrace_enabled = 0;
 
 	/* check the trace buffer */
-	ret = trace_test_buffer(tr, &count);
+	ret = trace_test_buffer(&tr->trace_buffer, &count);
 	tracing_start();
 
 	/* we should only have one item */
···
 	ftrace_enabled = 0;
 
 	/* check the trace buffer */
-	ret = trace_test_buffer(tr, &count);
+	ret = trace_test_buffer(&tr->trace_buffer, &count);
 	trace->reset(tr);
 	tracing_start();
 
···
 /* Maximum number of functions to trace before diagnosing a hang */
 #define GRAPH_MAX_FUNC_TEST	100000000
 
-static void
-__ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode);
 static unsigned int graph_hang_thresh;
 
 /* Wrap the real function entry probe to avoid possible hanging */
···
 	if (unlikely(++graph_hang_thresh > GRAPH_MAX_FUNC_TEST)) {
 		ftrace_graph_stop();
 		printk(KERN_WARNING "BUG: Function graph tracer hang!\n");
-		if (ftrace_dump_on_oops)
-			__ftrace_dump(false, DUMP_ALL);
+		if (ftrace_dump_on_oops) {
+			ftrace_dump(DUMP_ALL);
+			/* ftrace_dump() disables tracing */
+			tracing_on();
+		}
 		return 0;
 	}
 
···
 	 * Simulate the init() callback but we attach a watchdog callback
 	 * to detect and recover from possible hangs
 	 */
-	tracing_reset_online_cpus(tr);
+	tracing_reset_online_cpus(&tr->trace_buffer);
 	set_graph_array(tr);
 	ret = register_ftrace_graph(&trace_graph_return,
 				    &trace_graph_entry_watchdog);
···
 	tracing_stop();
 
 	/* check the trace buffer */
-	ret = trace_test_buffer(tr, &count);
+	ret = trace_test_buffer(&tr->trace_buffer, &count);
 
 	trace->reset(tr);
 	tracing_start();
···
 	/* stop the tracing. */
 	tracing_stop();
 	/* check both trace buffers */
-	ret = trace_test_buffer(tr, NULL);
+	ret = trace_test_buffer(&tr->trace_buffer, NULL);
 	if (!ret)
-		ret = trace_test_buffer(&max_tr, &count);
+		ret = trace_test_buffer(&tr->max_buffer, &count);
 	trace->reset(tr);
 	tracing_start();
 
···
 	/* stop the tracing. */
 	tracing_stop();
 	/* check both trace buffers */
-	ret = trace_test_buffer(tr, NULL);
+	ret = trace_test_buffer(&tr->trace_buffer, NULL);
 	if (!ret)
-		ret = trace_test_buffer(&max_tr, &count);
+		ret = trace_test_buffer(&tr->max_buffer, &count);
 	trace->reset(tr);
 	tracing_start();
 
···
 	/* stop the tracing. */
 	tracing_stop();
 	/* check both trace buffers */
-	ret = trace_test_buffer(tr, NULL);
+	ret = trace_test_buffer(&tr->trace_buffer, NULL);
 	if (ret)
 		goto out;
 
-	ret = trace_test_buffer(&max_tr, &count);
+	ret = trace_test_buffer(&tr->max_buffer, &count);
 	if (ret)
 		goto out;
 
···
 	/* stop the tracing. */
 	tracing_stop();
 	/* check both trace buffers */
-	ret = trace_test_buffer(tr, NULL);
+	ret = trace_test_buffer(&tr->trace_buffer, NULL);
 	if (ret)
 		goto out;
 
-	ret = trace_test_buffer(&max_tr, &count);
+	ret = trace_test_buffer(&tr->max_buffer, &count);
 
 	if (!ret && !count) {
 		printk(KERN_CONT ".. no entries found ..");
···
 	/* stop the tracing. */
 	tracing_stop();
 	/* check both trace buffers */
-	ret = trace_test_buffer(tr, NULL);
+	ret = trace_test_buffer(&tr->trace_buffer, NULL);
 	printk("ret = %d\n", ret);
 	if (!ret)
-		ret = trace_test_buffer(&max_tr, &count);
+		ret = trace_test_buffer(&tr->max_buffer, &count);
 
 
 	trace->reset(tr);
···
 	/* stop the tracing. */
 	tracing_stop();
 	/* check the trace buffer */
-	ret = trace_test_buffer(tr, &count);
+	ret = trace_test_buffer(&tr->trace_buffer, &count);
 	trace->reset(tr);
 	tracing_start();
 

kernel/trace/trace_stack.c

···
 
 #define STACK_TRACE_ENTRIES 500
 
+#ifdef CC_USING_FENTRY
+# define fentry		1
+#else
+# define fentry		0
+#endif
+
 static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES+1] =
 	 { [0 ... (STACK_TRACE_ENTRIES)] = ULONG_MAX };
 static unsigned stack_dump_index[STACK_TRACE_ENTRIES];
 
+/*
+ * Reserve one entry for the passed in ip. This will allow
+ * us to remove most or all of the stack size overhead
+ * added by the stack tracer itself.
+ */
 static struct stack_trace max_stack_trace = {
-	.max_entries		= STACK_TRACE_ENTRIES,
-	.entries		= stack_dump_trace,
+	.max_entries		= STACK_TRACE_ENTRIES - 1,
+	.entries		= &stack_dump_trace[1],
 };
 
 static unsigned long max_stack_size;
···
 int stack_tracer_enabled;
 static int last_stack_tracer_enabled;
 
-static inline void check_stack(void)
+static inline void
+check_stack(unsigned long ip, unsigned long *stack)
 {
 	unsigned long this_size, flags;
 	unsigned long *p, *top, *start;
+	static int tracer_frame;
+	int frame_size = ACCESS_ONCE(tracer_frame);
 	int i;
 
-	this_size = ((unsigned long)&this_size) & (THREAD_SIZE-1);
+	this_size = ((unsigned long)stack) & (THREAD_SIZE-1);
 	this_size = THREAD_SIZE - this_size;
+	/* Remove the frame of the tracer */
+	this_size -= frame_size;
 
 	if (this_size <= max_stack_size)
 		return;
 
 	/* we do not handle interrupt stacks yet */
-	if (!object_is_on_stack(&this_size))
+	if (!object_is_on_stack(stack))
 		return;
 
 	local_irq_save(flags);
 	arch_spin_lock(&max_stack_lock);
+
+	/* In case another CPU set the tracer_frame on us */
+	if (unlikely(!frame_size))
+		this_size -= tracer_frame;
 
 	/* a race could have already updated it */
 	if (this_size <= max_stack_size)
···
 	save_stack_trace(&max_stack_trace);
 
 	/*
+	 * Add the passed in ip from the function tracer.
+	 * Searching for this on the stack will skip over
+	 * most of the overhead from the stack tracer itself.
+	 */
+	stack_dump_trace[0] = ip;
+	max_stack_trace.nr_entries++;
+
+	/*
 	 * Now find where in the stack these are.
 	 */
 	i = 0;
-	start = &this_size;
+	start = stack;
 	top = (unsigned long *)
 		(((unsigned long)start & ~(THREAD_SIZE-1)) + THREAD_SIZE);
 
···
 				found = 1;
 				/* Start the search from here */
 				start = p + 1;
+				/*
+				 * We do not want to show the overhead
+				 * of the stack tracer stack in the
+				 * max stack. If we haven't figured
+				 * out what that is, then figure it out
+				 * now.
+				 */
+				if (unlikely(!tracer_frame) && i == 1) {
+					tracer_frame = (p - stack) *
+						sizeof(unsigned long);
+					max_stack_size -= tracer_frame;
+				}
 			}
 		}
 
···
 stack_trace_call(unsigned long ip, unsigned long parent_ip,
 		 struct ftrace_ops *op, struct pt_regs *pt_regs)
 {
+	unsigned long stack;
 	int cpu;
 
 	preempt_disable_notrace();
···
 	if (per_cpu(trace_active, cpu)++ != 0)
 		goto out;
 
-	check_stack();
+	/*
+	 * When fentry is used, the traced function does not get
+	 * its stack frame set up, and we lose the parent.
+	 * The ip is pretty useless because the function tracer
+	 * was called before that function set up its stack frame.
+	 * In this case, we use the parent ip.
+	 *
+	 * By adding the return address of either the parent ip
+	 * or the current ip we can disregard most of the stack usage
+	 * caused by the stack tracer itself.
+	 *
+	 * The function tracer always reports the address of where the
+	 * mcount call was, but the stack will hold the return address.
+	 */
+	if (fentry)
+		ip = parent_ip;
+	else
+		ip += MCOUNT_INSN_SIZE;
+
+	check_stack(ip, &stack);
 
  out:
 	per_cpu(trace_active, cpu)--;
···
 	struct dentry *d_tracer;
 
 	d_tracer = tracing_init_dentry();
+	if (!d_tracer)
+		return 0;
 
 	trace_create_file("stack_max_size", 0644, d_tracer,
 			&max_stack_size, &stack_max_size_fops);

kernel/trace/trace_stat.c

···
 	struct dentry *d_tracing;
 
 	d_tracing = tracing_init_dentry();
+	if (!d_tracing)
+		return 0;
 
 	stat_dir = debugfs_create_dir("trace_stat", d_tracing);
 	if (!stat_dir)

kernel/trace/trace_syscalls.c

···
 #include "trace.h"
 
 static DEFINE_MUTEX(syscall_trace_lock);
-static int sys_refcount_enter;
-static int sys_refcount_exit;
-static DECLARE_BITMAP(enabled_enter_syscalls, NR_syscalls);
-static DECLARE_BITMAP(enabled_exit_syscalls, NR_syscalls);
 
 static int syscall_enter_register(struct ftrace_event_call *event,
 				 enum trace_reg type, void *data);
···
 	/*
 	 * Only compare after the "sys" prefix. Archs that use
 	 * syscall wrappers may have syscalls symbols aliases prefixed
-	 * with "SyS" instead of "sys", leading to an unwanted
+	 * with ".SyS" or ".sys" instead of "sys", leading to an unwanted
 	 * mismatch.
 	 */
 	return !strcmp(sym + 3, name + 3);
···
 		kfree(call->print_fmt);
 }
 
-static int syscall_enter_define_fields(struct ftrace_event_call *call)
+static int __init syscall_enter_define_fields(struct ftrace_event_call *call)
 {
 	struct syscall_trace_enter trace;
 	struct syscall_metadata *meta = call->data;
···
 	return ret;
 }
 
-static int syscall_exit_define_fields(struct ftrace_event_call *call)
+static int __init syscall_exit_define_fields(struct ftrace_event_call *call)
 {
 	struct syscall_trace_exit trace;
 	int ret;
···
 	return ret;
 }
 
-static void ftrace_syscall_enter(void *ignore, struct pt_regs *regs, long id)
+static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
 {
+	struct trace_array *tr = data;
 	struct syscall_trace_enter *entry;
 	struct syscall_metadata *sys_data;
 	struct ring_buffer_event *event;
···
 	syscall_nr = trace_get_syscall_nr(current, regs);
 	if (syscall_nr < 0)
 		return;
-	if (!test_bit(syscall_nr, enabled_enter_syscalls))
+	if (!test_bit(syscall_nr, tr->enabled_enter_syscalls))
 		return;
 
 	sys_data = syscall_nr_to_meta(syscall_nr);
···
 
 	size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
 
-	event = trace_current_buffer_lock_reserve(&buffer,
+	buffer = tr->trace_buffer.buffer;
+	event = trace_buffer_lock_reserve(buffer,
 			sys_data->enter_event->event.type, size, 0, 0);
 	if (!event)
 		return;
···
 		trace_current_buffer_unlock_commit(buffer, event, 0, 0);
 }
 
-static void ftrace_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
+static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
 {
+	struct trace_array *tr = data;
 	struct syscall_trace_exit *entry;
 	struct syscall_metadata *sys_data;
 	struct ring_buffer_event *event;
···
 	syscall_nr = trace_get_syscall_nr(current, regs);
 	if (syscall_nr < 0)
 		return;
-	if (!test_bit(syscall_nr, enabled_exit_syscalls))
+	if (!test_bit(syscall_nr, tr->enabled_exit_syscalls))
 		return;
 
 	sys_data = syscall_nr_to_meta(syscall_nr);
 	if (!sys_data)
 		return;
 
-	event = trace_current_buffer_lock_reserve(&buffer,
+	buffer = tr->trace_buffer.buffer;
+	event = trace_buffer_lock_reserve(buffer,
 			sys_data->exit_event->event.type, sizeof(*entry), 0, 0);
 	if (!event)
 		return;
···
 		trace_current_buffer_unlock_commit(buffer, event, 0, 0);
 }
 
-static int reg_event_syscall_enter(struct ftrace_event_call *call)
+static int reg_event_syscall_enter(struct ftrace_event_file *file,
+				   struct ftrace_event_call *call)
 {
+	struct trace_array *tr = file->tr;
 	int ret = 0;
 	int num;
 
···
 	if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 		return -ENOSYS;
 	mutex_lock(&syscall_trace_lock);
-	if (!sys_refcount_enter)
-		ret = register_trace_sys_enter(ftrace_syscall_enter, NULL);
+	if (!tr->sys_refcount_enter)
+		ret = register_trace_sys_enter(ftrace_syscall_enter, tr);
 	if (!ret) {
-		set_bit(num, enabled_enter_syscalls);
-		sys_refcount_enter++;
+		set_bit(num, tr->enabled_enter_syscalls);
+		tr->sys_refcount_enter++;
 	}
 	mutex_unlock(&syscall_trace_lock);
 	return ret;
 }
 
-static void unreg_event_syscall_enter(struct ftrace_event_call *call)
+static void unreg_event_syscall_enter(struct ftrace_event_file *file,
+				      struct ftrace_event_call *call)
 {
+	struct trace_array *tr = file->tr;
 	int num;
 
 	num = ((struct syscall_metadata *)call->data)->syscall_nr;
 	if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 		return;
 	mutex_lock(&syscall_trace_lock);
-	sys_refcount_enter--;
-	clear_bit(num, enabled_enter_syscalls);
-	if (!sys_refcount_enter)
-		unregister_trace_sys_enter(ftrace_syscall_enter, NULL);
+	tr->sys_refcount_enter--;
+	clear_bit(num, tr->enabled_enter_syscalls);
+	if (!tr->sys_refcount_enter)
+		unregister_trace_sys_enter(ftrace_syscall_enter, tr);
 	mutex_unlock(&syscall_trace_lock);
 }
 
-static int reg_event_syscall_exit(struct ftrace_event_call *call)
+static int reg_event_syscall_exit(struct ftrace_event_file *file,
+				  struct ftrace_event_call *call)
 {
+	struct trace_array *tr = file->tr;
 	int ret = 0;
 	int num;
 
···
 	if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 		return -ENOSYS;
 	mutex_lock(&syscall_trace_lock);
-	if (!sys_refcount_exit)
-		ret = register_trace_sys_exit(ftrace_syscall_exit, NULL);
+	if (!tr->sys_refcount_exit)
+		ret = register_trace_sys_exit(ftrace_syscall_exit, tr);
 	if (!ret) {
-		set_bit(num, enabled_exit_syscalls);
-		sys_refcount_exit++;
+		set_bit(num, tr->enabled_exit_syscalls);
+		tr->sys_refcount_exit++;
 	}
 	mutex_unlock(&syscall_trace_lock);
 	return ret;
 }
 
-static void unreg_event_syscall_exit(struct ftrace_event_call *call)
+static void unreg_event_syscall_exit(struct ftrace_event_file *file,
+				     struct ftrace_event_call *call)
 {
+	struct trace_array *tr = file->tr;
 	int num;
 
 	num = ((struct syscall_metadata *)call->data)->syscall_nr;
 	if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 		return;
 	mutex_lock(&syscall_trace_lock);
-	sys_refcount_exit--;
-	clear_bit(num, enabled_exit_syscalls);
-	if (!sys_refcount_exit)
-		unregister_trace_sys_exit(ftrace_syscall_exit, NULL);
+	tr->sys_refcount_exit--;
+	clear_bit(num, tr->enabled_exit_syscalls);
+	if (!tr->sys_refcount_exit)
+		unregister_trace_sys_exit(ftrace_syscall_exit, tr);
 	mutex_unlock(&syscall_trace_lock);
 }
 
···
 	.trace		= print_syscall_exit,
 };
 
-struct ftrace_event_class event_class_syscall_enter = {
+struct ftrace_event_class __refdata event_class_syscall_enter = {
 	.system		= "syscalls",
 	.reg		= syscall_enter_register,
 	.define_fields	= syscall_enter_define_fields,
···
 	.raw_init	= init_syscall_trace,
 };
 
-struct ftrace_event_class event_class_syscall_exit = {
+struct ftrace_event_class __refdata event_class_syscall_exit = {
 	.system		= "syscalls",
 	.reg		= syscall_exit_register,
 	.define_fields	= syscall_exit_define_fields,
···
 static int syscall_enter_register(struct ftrace_event_call *event,
 				 enum trace_reg type, void *data)
 {
+	struct ftrace_event_file *file = data;
+
 	switch (type) {
 	case TRACE_REG_REGISTER:
-		return reg_event_syscall_enter(event);
+		return reg_event_syscall_enter(file, event);
 	case TRACE_REG_UNREGISTER:
-		unreg_event_syscall_enter(event);
+		unreg_event_syscall_enter(file, event);
 		return 0;
 
 #ifdef CONFIG_PERF_EVENTS
···
 static int syscall_exit_register(struct ftrace_event_call *event,
 				 enum trace_reg type, void *data)
 {
+	struct ftrace_event_file *file = data;
+
 	switch (type) {
 	case TRACE_REG_REGISTER:
-		return reg_event_syscall_exit(event);
+		return reg_event_syscall_exit(file, event);
 	case TRACE_REG_UNREGISTER:
-		unreg_event_syscall_exit(event);
+		unreg_event_syscall_exit(file, event);
 		return 0;
 
 #ifdef CONFIG_PERF_EVENTS

kernel/tracepoint.c

···
 	int nr_probes = 0;
 	struct tracepoint_func *old, *new;
 
-	WARN_ON(!probe);
+	if (WARN_ON(!probe))
+		return ERR_PTR(-EINVAL);
 
 	debug_print_probes(entry);
 	old = entry->funcs;
···
 
 	debug_print_probes(entry);
 	/* (N -> M), (N > 1, M >= 0) probes */
-	for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
-		if (!probe ||
-		    (old[nr_probes].func == probe &&
-		     old[nr_probes].data == data))
-			nr_del++;
+	if (probe) {
+		for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
+			if (old[nr_probes].func == probe &&
+			     old[nr_probes].data == data)
+				nr_del++;
+		}
 	}
 
+	/*
+	 * If probe is NULL, then nr_probes = nr_del = 0, and then the
+	 * entire entry will be removed.
+	 */
 	if (nr_probes - nr_del == 0) {
 		/* N -> 0, (N > 1) */
 		entry->funcs = NULL;
···
 		if (new == NULL)
 			return ERR_PTR(-ENOMEM);
 		for (i = 0; old[i].func; i++)
-			if (probe &&
-			    (old[i].func != probe || old[i].data != data))
+			if (old[i].func != probe || old[i].data != data)
 				new[j++] = old[i];
 		new[nr_probes - nr_del].func = NULL;
 		entry->refcount = nr_probes - nr_del;