No description
  • C 98.2%
  • Assembly 1%
  • Makefile 0.3%
  • Shell 0.2%
  • Python 0.1%
Find a file
Repository files (latest commit first)
Filename Latest commit message Latest commit date
Julia Cartwright ce4d6fff7a watchdog: prevent deferral of watchdogd wakeup on RT
[ Upstream commit a19f89335f4bda3d77d991c96583e3e51856acbb ]

When PREEMPT_RT is enabled, all hrtimer expiry functions are
deferred for execution into the context of ksoftirqd unless otherwise
annotated.

Deferring the expiry of the hrtimer used by the watchdog core, however,
is a waste, as the callback does nothing but queue a kthread work item
and wakeup watchdogd.

It's worst then that, too: the deferral through ksoftirqd also means
that for correct behavior a user must adjust the scheduling parameters
of both watchdogd _and_ ksoftirqd, which is unnecessary and has other
side effects (like causing unrelated expiry functions to execute at
potentially elevated priority).

Instead, mark the hrtimer used by the watchdog core as being _HARD to
allow it's execution directly from hardirq context.  The work done in
this expiry function is well-bounded and minimal.

A user still must adjust the scheduling parameters of the watchdogd
to be correct w.r.t. their application needs.

Link: https://lkml.kernel.org/r/0e02d8327aeca344096c246713033887bc490dd7.1538089180.git.julia@ni.com
Cc: Guenter Roeck <linux@roeck-us.net>
Reported-and-tested-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Reported-by: Tim Sander <tim@krieglstein.org>
Signed-off-by: Julia Cartwright <julia@ni.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
[bigeasy: use only HRTIMER_MODE_REL_HARD]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20191105144506.clyadjbvnn7b7b2m@linutronix.de
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-01-04 19:18:13 +01:00
arch ARM: 8937/1: spectre-v2: remove Brahma-B53 from hardening 2020-01-04 19:18:12 +01:00
block iocost: over-budget forced IOs should schedule async delay 2019-12-31 16:46:19 +01:00
certs PKCS#7: Refactor verify_pkcs7_signature() 2019-08-05 18:40:18 -04:00
crypto KEYS: asymmetric: return ENOMEM if akcipher_request_alloc() fails 2019-12-31 16:46:07 +01:00
Documentation dt-bindings: Improve validation build error handling 2020-01-04 19:18:11 +01:00
drivers watchdog: prevent deferral of watchdogd wakeup on RT 2020-01-04 19:18:13 +01:00
fs iomap: fix return value of iomap_dio_bio_actor on 32bit systems 2020-01-04 19:17:31 +01:00
include fs/quota: handle overflows of sysctl fs.quota.* and report as unsigned long 2020-01-04 19:17:25 +01:00
init Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-09-28 08:14:15 -07:00
ipc ipc/sem.c: convert to use built-in RCU list checking 2019-09-25 17:51:41 -07:00
kernel dma-mapping: fix handling of dma-ranges for reserved memory (again) 2020-01-04 19:17:00 +01:00
lib ubsan, x86: Annotate and allow __ubsan_handle_shift_out_of_bounds() in uaccess regions 2019-12-31 16:44:25 +01:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm mm: vmscan: protect shrinker idr replace with CONFIG_MEMCG 2019-12-31 16:46:07 +01:00
net can: j1939: j1939_sk_bind(): take priv after lock is held 2019-12-31 16:45:56 +01:00
samples samples: pktgen: fix proc_cmd command result check logic 2019-12-31 16:43:45 +01:00
scripts dtc: Use pkg-config to locate libyaml 2020-01-04 19:17:09 +01:00
security efi/efi_test: Lock down /dev/efi_test and require CAP_SYS_ADMIN 2019-10-31 09:40:21 +01:00
sound ASoC: soc-pcm: check symmetry before hw_params 2019-12-31 16:45:42 +01:00
tools selftests/powerpc: Skip tm-signal-sigreturn-nt if TM not available 2020-01-04 19:17:10 +01:00
usr kbuild: update compile-test header list for v5.4-rc2 2019-10-05 15:29:49 +09:00
virt KVM: arm/arm64: Properly handle faulting of device mappings 2019-12-31 16:46:24 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes
.gitignore Modules updates for v5.4 2019-09-22 10:34:46 -07:00
.mailmap ARM: SoC fixes 2019-11-10 13:41:59 -08:00
COPYING
CREDITS MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer 2019-10-10 08:12:51 -07:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-11-22 14:28:14 -08:00
Makefile Linux 5.4.7 2019-12-31 16:46:36 +01:00
README

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 Restructured Text 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.