Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.
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Pull locking fix from Thomas Gleixner:
"rt_mutex_futex_unlock() grew a new irq-off call site, but the function
assumes that its always called from irq enabled context.
Use (un)lock_irqsafe() to handle the new call site correctly"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
rtmutex: Make rt_mutex_futex_unlock() safe for irq-off callsites
Pull dmaengine fixes from Vinod Koul:
"Two small fixes are for this cycle:
- fix max_chunk_size for rcar-dmac for R-Car Gen3
- fix clock resource of mv_xor_v2"
* tag 'dmaengine-fix-4.16-rc5' of git://git.infradead.org/users/vkoul/slave-dma:
dmaengine: mv_xor_v2: Fix clock resource by adding a register clock
dmaengine: rcar-dmac: fix max_chunk_size for R-Car Gen3
When running rcutorture with TREE03 config, CONFIG_PROVE_LOCKING=y, and
kernel cmdline argument "rcutorture.gp_exp=1", lockdep reports a
HARDIRQ-safe->HARDIRQ-unsafe deadlock:
================================
WARNING: inconsistent lock state
4.16.0-rc4+ #1 Not tainted
--------------------------------
inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.
takes:
__schedule+0xbe/0xaf0
{IN-HARDIRQ-W} state was registered at:
_raw_spin_lock+0x2a/0x40
scheduler_tick+0x47/0xf0
...
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&rq->lock);
<Interrupt>
lock(&rq->lock);
*** DEADLOCK ***
1 lock held by rcu_torture_rea/724:
rcu_torture_read_lock+0x0/0x70
stack backtrace:
CPU: 2 PID: 724 Comm: rcu_torture_rea Not tainted 4.16.0-rc4+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-20171110_100015-anatol 04/01/2014
Call Trace:
lock_acquire+0x90/0x200
? __schedule+0xbe/0xaf0
_raw_spin_lock+0x2a/0x40
? __schedule+0xbe/0xaf0
__schedule+0xbe/0xaf0
preempt_schedule_irq+0x2f/0x60
retint_kernel+0x1b/0x2d
RIP: 0010:rcu_read_unlock_special+0x0/0x680
? rcu_torture_read_unlock+0x60/0x60
__rcu_read_unlock+0x64/0x70
rcu_torture_read_unlock+0x17/0x60
rcu_torture_reader+0x275/0x450
? rcutorture_booster_init+0x110/0x110
? rcu_torture_stall+0x230/0x230
? kthread+0x10e/0x130
kthread+0x10e/0x130
? kthread_create_worker_on_cpu+0x70/0x70
? call_usermodehelper_exec_async+0x11a/0x150
ret_from_fork+0x3a/0x50
This happens with the following even sequence:
preempt_schedule_irq();
local_irq_enable();
__schedule():
local_irq_disable(); // irq off
...
rcu_note_context_switch():
rcu_note_preempt_context_switch():
rcu_read_unlock_special():
local_irq_save(flags);
...
raw_spin_unlock_irqrestore(...,flags); // irq remains off
rt_mutex_futex_unlock():
raw_spin_lock_irq();
...
raw_spin_unlock_irq(); // accidentally set irq on
<return to __schedule()>
rq_lock():
raw_spin_lock(); // acquiring rq->lock with irq on
which means rq->lock becomes a HARDIRQ-unsafe lock, which can cause
deadlocks in scheduler code.
This problem was introduced by commit 02a7c234e540 ("rcu: Suppress
lockdep false-positive ->boost_mtx complaints"). That brought the user
of rt_mutex_futex_unlock() with irq off.
To fix this, replace the *lock_irq() in rt_mutex_futex_unlock() with
*lock_irq{save,restore}() to make it safe to call rt_mutex_futex_unlock()
with irq off.
Fixes: 02a7c234e540 ("rcu: Suppress lockdep false-positive ->boost_mtx complaints")
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>
Link: https://lkml.kernel.org/r/20180309065630.8283-1-boqun.feng@gmail.com
Pull GPIO fix from Linus Walleij:
"This is a single GPIO fix for the v4.16 series affecting the Renesas
driver, and fixes wakeup from external stuff"
* tag 'gpio-v4.16-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio:
gpio: rcar: Use wakeup_path i.s.o. explicit clock handling
On the CP110 components which are present on the Armada 7K/8K SoC we need
to explicitly enable the clock for the registers. However it is not
needed for the AP8xx component, that's why this clock is optional.
With this patch both clock have now a name, but in order to be backward
compatible, the name of the first clock is not used. It allows to still
use this clock with a device tree using the old binding.
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Pull virtio bugfix from Michael Tsirkin:
"A bugfix for error handling in virtio"
* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
virtio_ring: fix num_free handling in error case
Pull Kbuild fixes from Masahiro Yamada:
- make fixdep parse kconfig.h to fix missing rebuild
- replace hyphens with underscores in builtin DTB label names
- fix typos
* tag 'kbuild-fixes-v4.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
kbuild: Handle builtin dtb file names containing hyphens
scripts/bloat-o-meter: fix typos in help
fixdep: do not ignore kconfig.h
fixdep: remove some false CONFIG_ matches
fixdep: remove stale references to uml-config.h
Since commit ab82fa7da4dce5c7 ("gpio: rcar: Prevent module clock disable
when wake-up is enabled"), when a GPIO is used for wakeup, the GPIO
block's module clock (if exists) is manually kept running during system
suspend, to make sure the device stays active.
However, this explicit clock handling is merely a workaround for a
failure to properly communicate wakeup information to the device core.
Instead, set the device's power.wakeup_path field, to indicate this
device is part of the wakeup path. Depending on the PM Domain's
active_wakeup configuration, the genpd core code will keep the device
enabled (and the clock running) during system suspend when needed.
This allows for the removal of all explicit clock handling code from the
driver.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
According to R-Car Gen3 Rev.0.80 manual, the DMATCR can be set to
16,777,215 as maximum. So, this patch fixes the max_chunk_size for
safety on all of SoCs. Otherwise, a system may hang if the DMATCR
is set to 0 on R-Car Gen3.
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Pull input fixes from Dmitry Torokhov:
- we are reverting patch that was switched touchpad on Lenovo T460P
over to native RMI because on these boxes BIOS messes up with SMBus
controller state. We might re-enable it later once SMBus issue is
resolved
- disabling interrupts in matrix_keypad driver was racy
- mms114 now has SPDX header and matching MODULE_LICENSE
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
Revert "Input: synaptics - Lenovo Thinkpad T460p devices should use RMI"
Input: matrix_keypad - fix race when disabling interrupts
Input: mms114 - add SPDX identifier
Input: mms114 - fix license module information
The vq->vq.num_free hasn't been changed when error happens,
so it shouldn't be changed when handling the error.
Fixes: 780bc7903a32 ("virtio_ring: Support DMA APIs")
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Pull watchdog fixes from Wim Van Sebroeck:
- f71808e_wdt: Fix magic close handling
- sbsa: 32-bit read fix for WCV
- hpwdt: Remove legacy NMI sourcing
* tag 'linux-watchdog-4.16-fixes-2' of git://www.linux-watchdog.org/linux-watchdog:
watchdog: hpwdt: Remove legacy NMI sourcing.
watchdog: sbsa: use 32-bit read for WCV
watchdog: f71808e_wdt: Fix magic close handling
cmd_dt_S_dtb constructs the assembly source to incorporate a devicetree
FDT (that is, the .dtb file) as binary data in the kernel image. This
assembly source contains labels before and after the binary data. The
label names incorporate the file name of the corresponding .dtb file.
Hyphens are not legal characters in labels, so .dtb files built into the
kernel with hyphens in the file name result in errors like the
following:
bcm3368-netgear-cvg834g.dtb.S: Assembler messages:
bcm3368-netgear-cvg834g.dtb.S:5: Error: : no such section
bcm3368-netgear-cvg834g.dtb.S:5: Error: junk at end of line, first unrecognized character is `-'
bcm3368-netgear-cvg834g.dtb.S:6: Error: unrecognized opcode `__dtb_bcm3368-netgear-cvg834g_begin:'
bcm3368-netgear-cvg834g.dtb.S:8: Error: unrecognized opcode `__dtb_bcm3368-netgear-cvg834g_end:'
bcm3368-netgear-cvg834g.dtb.S:9: Error: : no such section
bcm3368-netgear-cvg834g.dtb.S:9: Error: junk at end of line, first unrecognized character is `-'
Fix this by updating cmd_dt_S_dtb to transform all hyphens from the file
name to underscores when constructing the labels.
As of v4.16-rc2, 1139 .dts files across ARM64, ARM, MIPS and PowerPC
contain hyphens in their names, but the issue only currently manifests
on Broadcom MIPS platforms, as that is the only place where such files
are built into the kernel. For example when CONFIG_DT_NETGEAR_CVG834G=y,
or on BMIPS kernels when the dtbs target is used (in the latter case it
admittedly shouldn't really build all the dtb.o files, but thats a
separate issue).
Fixes: 695835511f96 ("MIPS: BMIPS: rename bcm96358nb4ser to bcm6358-neufbox4-sercom")
Signed-off-by: James Hogan <jhogan@kernel.org>
Reviewed-by: Frank Rowand <frowand.list@gmail.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: <stable@vger.kernel.org> # 4.9+
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>