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watchdog/hardlockup: sort hardlockup detector related config values a logical way 

Patch series "watchdog/hardlockup: Cleanup configuration of hardlockup
detectors", v2.

Clean up watchdog Kconfig after introducing the buddy detector.


This patch (of 6):

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.

Only one hardlockup detector can be compiled in. The selection is done
using quite complex dependencies between several CONFIG variables.
The following patches will try to make it more straightforward.

As a first step, reorder the definitions of the various CONFIG variables.
The logical order is:

   1. HAVE_* variables define available variants. They are typically
      defined in the arch/ config files.

   2. HARDLOCKUP_DETECTOR y/n variable defines whether the hardlockup
      detector is enabled at all.

   3. HARDLOCKUP_DETECTOR_PREFER_BUDDY y/n variable defines whether
      the buddy detector should be preferred over the perf one.
      Note that the arch specific variants are always preferred when
      available.

   4. HARDLOCKUP_DETECTOR_PERF/BUDDY variables define whether the given
      detector is enabled in the end.

   5. HAVE_HARDLOCKUP_DETECTOR_NON_ARCH and HARDLOCKUP_DETECTOR_NON_ARCH
      are temporary variables that are going to be removed in
      a followup patch.

This is a preparation step for further cleanup. It will change the logic
without shuffling the definitions.

This change temporary breaks the C-like ordering where the variables are
declared or defined before they are used. It is not really needed for
Kconfig. Also the following patches will rework the logic so that
the ordering will be C-like in the end.

The patch just shuffles the definitions. It should not change the existing
behavior.

Link: https://lkml.kernel.org/r/20230616150618.6073-1-pmladek@suse.com
Link: https://lkml.kernel.org/r/20230616150618.6073-2-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 17:06:13 +02:00 committed by Andrew Morton
parent 28168eca32
commit 4917a25f83
1 changed files with 56 additions and 56 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

112
lib/Kconfig.debug
View File

@ -1035,62 +1035,6 @@ config BOOTPARAM_SOFTLOCKUP_PANIC
Say N if unsure.
# 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
config HARDLOCKUP_DETECTOR_PERF
bool
depends on HAVE_HARDLOCKUP_DETECTOR_PERF
select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
config HARDLOCKUP_DETECTOR_BUDDY
bool
depends on SMP
select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
# 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
config HARDLOCKUP_DETECTOR_PREFER_BUDDY
bool "Prefer the buddy CPU hardlockup detector"
depends on HAVE_HARDLOCKUP_DETECTOR_PERF && SMP
help
Say Y here to prefer the buddy hardlockup detector over the perf one.
With the buddy detector, each CPU uses its softlockup hrtimer
to check that the next CPU is processing hrtimer interrupts by
verifying that a counter is increasing.
This hardlockup detector is useful on systems that don't have
an arch-specific hardlockup detector or if resources needed
for the hardlockup detector are better used for other things.
# 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.
#
config HARDLOCKUP_CHECK_TIMESTAMP
bool
#
# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
# lockup detector rather than the perf based detector.
@ -1111,6 +1055,62 @@ config HARDLOCKUP_DETECTOR
chance to run. The current stack trace is displayed upon detection
and the system will stay locked up.
config HARDLOCKUP_DETECTOR_PREFER_BUDDY
bool "Prefer the buddy CPU hardlockup detector"
depends on HAVE_HARDLOCKUP_DETECTOR_PERF && SMP
help
Say Y here to prefer the buddy hardlockup detector over the perf one.
With the buddy detector, each CPU uses its softlockup hrtimer
to check that the next CPU is processing hrtimer interrupts by
verifying that a counter is increasing.
This hardlockup detector is useful on systems that don't have
an arch-specific hardlockup detector or if resources needed
for the hardlockup detector are better used for other things.
config HARDLOCKUP_DETECTOR_PERF
bool
depends on HAVE_HARDLOCKUP_DETECTOR_PERF
select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
config HARDLOCKUP_DETECTOR_BUDDY
bool
depends on SMP
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.
#
config HARDLOCKUP_CHECK_TIMESTAMP
bool
config BOOTPARAM_HARDLOCKUP_PANIC
bool "Panic (Reboot) On Hard Lockups"
depends on HARDLOCKUP_DETECTOR