ich777/linux_media
1
0
Fork 0
mirror of https://github.com/tbsdtv/linux_media.git synced 2025-07-23 04:33:26 +02:00
Code Issues Packages Projects Releases Wiki Activity

watchdog/hardlockup: make the config checks more straightforward

Browse Source 
There are four possible variants of hardlockup detectors:

  + buddy: available when SMP is set.

  + perf: available when HAVE_HARDLOCKUP_DETECTOR_PERF is set.

  + arch-specific: available when HAVE_HARDLOCKUP_DETECTOR_ARCH is set.

  + sparc64 special variant: available when HAVE_NMI_WATCHDOG is set
	and HAVE_HARDLOCKUP_DETECTOR_ARCH is not set.

The check for the sparc64 variant is more complicated because
HAVE_NMI_WATCHDOG is used to #ifdef code used by both arch-specific
and sparc64 specific variant. Therefore it is automatically
selected with HAVE_HARDLOCKUP_DETECTOR_ARCH.

This complexity is partly hidden in HAVE_HARDLOCKUP_DETECTOR_NON_ARCH.
It reduces the size of some checks but it makes them harder to follow.

Finally, the other temporary variable HARDLOCKUP_DETECTOR_NON_ARCH
is used to re-compute HARDLOCKUP_DETECTOR_PERF/BUDDY when the global
HARDLOCKUP_DETECTOR switch is enabled/disabled.

Make the logic more straightforward by the following changes:

  + Better explain the role of HAVE_HARDLOCKUP_DETECTOR_ARCH and
    HAVE_NMI_WATCHDOG in comments.

  + Add HAVE_HARDLOCKUP_DETECTOR_BUDDY so that there is separate
    HAVE_* for all four hardlockup detector variants.

    Use it in the other conditions instead of SMP. It makes it
    clear that it is about the buddy detector.

  + Open code HAVE_HARDLOCKUP_DETECTOR_NON_ARCH in HARDLOCKUP_DETECTOR
    and HARDLOCKUP_DETECTOR_PREFER_BUDDY. It helps to understand
    the conditions between the four hardlockup detector variants.

  + Define the exact conditions when HARDLOCKUP_DETECTOR_PERF/BUDDY
    can be enabled. It explains the dependency on the other
    hardlockup detector variants.

    Also it allows to remove HARDLOCKUP_DETECTOR_NON_ARCH by using "imply".
    It triggers re-evaluating HARDLOCKUP_DETECTOR_PERF/BUDDY when
    the global HARDLOCKUP_DETECTOR switch is changed.

  + Add dependency on HARDLOCKUP_DETECTOR so that the affected variables
    disappear when the hardlockup detectors are disabled.

    Another nice side effect is that HARDLOCKUP_DETECTOR_PREFER_BUDDY
    value is not preserved when the global switch is disabled.
    The user has to make the decision again when it gets re-enabled.

Link: https://lkml.kernel.org/r/20230616150618.6073-3-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Petr Mladek
2023-06-16 17:06:14 +02:00
committed by Andrew Morton
parent 4917a25f83
commit 1356d0b966
2 changed files with 53 additions and 32 deletions
Download Patch File Download Diff File Expand all files Collapse all files

62
lib/Kconfig.debug
View File

@@ -1035,16 +1035,33 @@ config BOOTPARAM_SOFTLOCKUP_PANIC
Say N if unsure.
config HAVE_HARDLOCKUP_DETECTOR_BUDDY
bool
depends on SMP
default y
#
# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
# lockup detector rather than the perf based detector.
# Global switch whether to build a hardlockup detector at all. It is available
# only when the architecture supports at least one implementation. There are
# two exceptions. The hardlockup detector is never enabled on:
#
# s390: it reported many false positives there
#
# sparc64: has a custom implementation which is not using the common
# hardlockup command line options and sysctl interface.
#
# Note that HAVE_NMI_WATCHDOG is used to distinguish the sparc64 specific
# implementaion. It is automatically enabled also for other arch-specific
# variants which set HAVE_HARDLOCKUP_DETECTOR_ARCH. It makes the check
# of avaialable and supported variants quite tricky.
#
config HARDLOCKUP_DETECTOR
bool "Detect Hard Lockups"
depends on DEBUG_KERNEL && !S390
depends on HAVE_HARDLOCKUP_DETECTOR_NON_ARCH || HAVE_HARDLOCKUP_DETECTOR_ARCH
depends on ((HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY) && !HAVE_NMI_WATCHDOG) || HAVE_HARDLOCKUP_DETECTOR_ARCH
imply HARDLOCKUP_DETECTOR_PERF
imply HARDLOCKUP_DETECTOR_BUDDY
select LOCKUP_DETECTOR
select HARDLOCKUP_DETECTOR_NON_ARCH if HAVE_HARDLOCKUP_DETECTOR_NON_ARCH
help
Say Y here to enable the kernel to act as a watchdog to detect
@@ -1055,9 +1072,14 @@ config HARDLOCKUP_DETECTOR
chance to run. The current stack trace is displayed upon detection
and the system will stay locked up.
#
# Note that arch-specific variants are always preferred.
#
config HARDLOCKUP_DETECTOR_PREFER_BUDDY
bool "Prefer the buddy CPU hardlockup detector"
depends on HAVE_HARDLOCKUP_DETECTOR_PERF && SMP
depends on HARDLOCKUP_DETECTOR
depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
depends on !HAVE_NMI_WATCHDOG
help
Say Y here to prefer the buddy hardlockup detector over the perf one.
@@ -1071,39 +1093,27 @@ config HARDLOCKUP_DETECTOR_PREFER_BUDDY
config HARDLOCKUP_DETECTOR_PERF
bool
depends on HAVE_HARDLOCKUP_DETECTOR_PERF
depends on HARDLOCKUP_DETECTOR
depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
depends on !HAVE_NMI_WATCHDOG
select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
config HARDLOCKUP_DETECTOR_BUDDY
bool
depends on SMP
depends on HARDLOCKUP_DETECTOR
depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
depends on !HAVE_NMI_WATCHDOG
select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
#
# Both the "perf" and "buddy" hardlockup detectors count hrtimer
# interrupts. This config enables functions managing this common code.
#
config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
bool
select SOFTLOCKUP_DETECTOR
# For hardlockup detectors you can have one directly provided by the arch
# or use a "non-arch" one. If you're using a "non-arch" one that is
# further divided the perf hardlockup detector (which, confusingly, needs
# arch-provided perf support) and the buddy hardlockup detector (which just
# needs SMP). In either case, using the "non-arch" code conflicts with
# the NMI watchdog code (which is sometimes used directly and sometimes used
# by the arch-provided hardlockup detector).
config HAVE_HARDLOCKUP_DETECTOR_NON_ARCH
bool
depends on (HAVE_HARDLOCKUP_DETECTOR_PERF || SMP) && !HAVE_NMI_WATCHDOG
default y
# This will select the appropriate non-arch hardlockdup detector
config HARDLOCKUP_DETECTOR_NON_ARCH
bool
depends on HAVE_HARDLOCKUP_DETECTOR_NON_ARCH
select HARDLOCKUP_DETECTOR_BUDDY if !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
#
# Enables a timestamp based low pass filter to compensate for perf based
# hard lockup detection which runs too fast due to turbo modes.