tjh.dev
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
code
Clone this repository
https://tangled.org/tjh.dev/kernel
git@gordian.tjh.dev:tjh.dev/kernel
For self-hosted knots, clone URLs may differ based on your setup.
Pull timer fix from Thomas Gleixner:
"A single fix for the PTP systemcounter mechanism:
The rework of this mechanism added a 'use_nsec' member to struct
system_counterval. get_device_system_crosststamp() instantiates that
struct on the stack and hands a pointer to the driver callback.
Only the drivers which set use_nsec to true, initialize that field,
but all others ignore it. As get_device_system_crosststamp() does not
initialize the struct, the use_nsec field contains random stack
content in those cases. That causes a miscalulation usually resulting
in a failing range check in the best case.
Initialize the structure before handing it to the drivers to cure
that"
* tag 'timers-urgent-2025-07-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
timekeeping: Zero initialize system_counterval when querying time from phc drivers
Pull spi fix from Mark Brown:
"One last fix for v6.16, removing some hard coding to avoid data
corruption on some NAND devices in the QPIC driver"
* tag 'spi-fix-v6.16-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi:
spi: spi-qpic-snand: don't hardcode ECC steps
Most drivers only populate the fields cycles and cs_id of system_counterval
in their get_time_fn() callback for get_device_system_crosststamp(), unless
they explicitly provide nanosecond values.
When the use_nsecs field was added to struct system_counterval, most
drivers did not care. Clock sources other than CSID_GENERIC could then get
converted in convert_base_to_cs() based on an uninitialized use_nsecs field,
which usually results in -EINVAL during the following range check.
Pass in a fully zero initialized system_counterval_t to cure that.
Fixes: 6b2e29977518 ("timekeeping: Provide infrastructure for converting to/from a base clock")
Signed-off-by: Markus Blöchl <markus@blochl.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20250720-timekeeping_uninit_crossts-v2-1-f513c885b7c2@blochl.de
Pull i2c fixes from Wolfram Sang:
- qup: avoid potential hang when waiting for bus idle
- tegra: improve ACPI reset error handling
- virtio: use interruptible wait to prevent hang during transfer
* tag 'i2c-for-6.16-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
i2c: qup: jump out of the loop in case of timeout
i2c: virtio: Avoid hang by using interruptible completion wait
i2c: tegra: Fix reset error handling with ACPI
NAND devices with different page sizes requires different number
of ECC steps, yet the qcom_spi_ecc_init_ctx_pipelined() function
sets 4 steps in 'ecc_cfg' unconditionally.
The correct number of the steps is calculated earlier in the
function already, so use that instead of the hardcoded value.
Fixes: 7304d1909080 ("spi: spi-qpic: add driver for QCOM SPI NAND flash Interface")
Signed-off-by: Gabor Juhos <j4g8y7@gmail.com>
Link: https://patch.msgid.link/20250723-qpic-snand-fix-steps-v1-1-d800695dde4c@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Pull clk fixes from Stephen Boyd:
"A few Allwinner clk driver fixes:
- Mark Allwinner A523 MBUS clock as critical to avoid
system stalls
- Fix names of CSI related clocks on Allwinner V3s. This
includes changes to the driver, DT bindings and DT files.
- Fix parents of TCON clock on Allwinner V3s"
* tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
clk: sunxi-ng: v3s: Fix TCON clock parents
clk: sunxi-ng: v3s: Fix CSI1 MCLK clock name
clk: sunxi-ng: v3s: Fix CSI SCLK clock name
clk: sunxi-ng: a523: Mark MBUS clock as critical
i2c-host-fixes for v6.16-rc8
qup: avoid potential hang when waiting for bus idle
tegra: improve ACPI reset error handling
virtio: use interruptible wait to prevent hang during transfer
The current SPI framework does not verify if the SPI device supports
8 IO mode when doing an 8-bit transfer. This patch adds a check to
ensure that if the transfer tx_nbits or rx_nbits is 8, the SPI mode must
support 8 IO. If not, an error is returned, preventing undefined behavior.
Fixes: d6a711a898672 ("spi: Fix OCTAL mode support")
Cc: stable@vger.kernel.org
Signed-off-by: Cheng Ming Lin <chengminglin@mxic.com.tw>
Link: https://patch.msgid.link/20250714031023.504752-1-linchengming884@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Pull tracing fixes from Steven Rostedt:
- Fix timerlat with use of FORTIFY_SOURCE
FORTIFY_SOURCE was added to the stack tracer where it compares the
entry->caller array to having entry->size elements.
timerlat has the following:
memcpy(&entry->caller, fstack->calls, size);
entry->size = size;
Which triggers FORTIFY_SOURCE as the caller is populated before the
entry->size is initialized.
Swap the order to satisfy FORTIFY_SOURCE logic.
- Add down_write(trace_event_sem) when adding trace events in modules
Trace events being added to the ftrace_events array are protected by
the trace_event_sem semaphore. But when loading modules that have
trace events, the addition of the events are not protected by the
semaphore and loading two modules that have events at the same time
can corrupt the list.
Also add a lockdep_assert_held(trace_event_sem) to
_trace_add_event_dirs() to confirm it is held when iterating the
list.
* tag 'trace-v6.16-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing: Add down_write(trace_event_sem) when adding trace event
tracing/osnoise: Fix crash in timerlat_dump_stack()
Pull ARM fixes from Russell King:
- use an absolute path for asm/unified.h in KBUILD_AFLAGS to solve a
regression caused by commit d5c8d6e0fa61 ("kbuild: Update assembler
calls to use proper flags and language target")
- fix dead code elimination binutils version check again
* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rmk/linux:
ARM: 9450/1: Fix allowing linker DCE with binutils < 2.36
ARM: 9448/1: Use an absolute path to unified.h in KBUILD_AFLAGS
Pull Allwinner clock fixes from Chen-Yu Tsai:
- Mark A523 MBUS clock as critical
- Fix names of CSI related clocks on V3s
This includes changes to the driver, DT bindings and DT files.
- Fix parents of TCON clock on V3s
* tag 'sunxi-clk-fixes-for-6.16' of https://git.kernel.org/pub/scm/linux/kernel/git/sunxi/linux:
clk: sunxi-ng: v3s: Fix TCON clock parents
clk: sunxi-ng: v3s: Fix CSI1 MCLK clock name
clk: sunxi-ng: v3s: Fix CSI SCLK clock name
clk: sunxi-ng: a523: Mark MBUS clock as critical
Original logic only sets the return value but doesn't jump out of the
loop if the bus is kept active by a client. This is not expected. A
malicious or buggy i2c client can hang the kernel in this case and
should be avoided. This is observed during a long time test with a
PCA953x GPIO extender.
Fix it by changing the logic to not only sets the return value, but also
jumps out of the loop and return to the caller with -ETIMEDOUT.
Fixes: fbfab1ab0658 ("i2c: qup: reorganization of driver code to remove polling for qup v1")
Signed-off-by: Yang Xiwen <forbidden405@outlook.com>
Cc: <stable@vger.kernel.org> # v4.17+
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20250616-qca-i2c-v1-1-2a8d37ee0a30@outlook.com
Pull i2c fixes from Wolfram Sang:
"omap:
- add missing error check
- fix PM disable in probe error path
stm32:
- unmap DMA buffer on transfer failure
- use correct device when mapping and unmapping during transfers"
* tag 'i2c-for-6.16-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
i2c: stm32f7: unmap DMA mapped buffer
i2c: stm32: fix the device used for the DMA map
i2c: omap: Fix an error handling path in omap_i2c_probe()
i2c: omap: Handle omap_i2c_init() errors in omap_i2c_probe()
When a module is loaded, it adds trace events defined by the module. It
may also need to modify the modules trace printk formats to replace enum
names with their values.
If two modules are loaded at the same time, the adding of the event to the
ftrace_events list can corrupt the walking of the list in the code that is
modifying the printk format strings and crash the kernel.
The addition of the event should take the trace_event_sem for write while
it adds the new event.
Also add a lockdep_assert_held() on that semaphore in
__trace_add_event_dirs() as it iterates the list.
Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://lore.kernel.org/20250718223158.799bfc0c@batman.local.home
Reported-by: Fusheng Huang(黄富生) <Fusheng.Huang@luxshare-ict.com>
Closes: https://lore.kernel.org/all/20250717105007.46ccd18f@batman.local.home/
Fixes: 110bf2b764eb6 ("tracing: add protection around module events unload")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
README