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authorPetr Mladek <pmladek@suse.com>2023-06-16 18:06:14 +0300
committerAndrew Morton <akpm@linux-foundation.org>2023-06-20 02:25:28 +0300
commit1356d0b966e7ed81832af35478b913495cf7792e (patch)
tree62e920c9e489f01a51b7c2f5e631d713ec85a47c /arch/Kconfig
parent4917a25f83a8dc95eafd0107be87d4340f48d265 (diff)
downloadlinux-1356d0b966e7ed81832af35478b913495cf7792e.tar.xz
watchdog/hardlockup: make the config checks more straightforward
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>
Diffstat (limited to 'arch/Kconfig')
-rw-r--r--arch/Kconfig23
1 files changed, 17 insertions, 6 deletions
diff --git a/arch/Kconfig b/arch/Kconfig
index 422f0ffa269e..77e5af5fda3f 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -404,17 +404,28 @@ config HAVE_NMI_WATCHDOG
depends on HAVE_NMI
bool
help
- The arch provides a low level NMI watchdog. It provides
- asm/nmi.h, and defines its own watchdog_hardlockup_probe() and
- arch_touch_nmi_watchdog().
+ The arch provides its own hardlockup detector implementation instead
+ of the generic ones.
+
+ Sparc64 defines this variable without HAVE_HARDLOCKUP_DETECTOR_ARCH.
+ It is the last arch-specific implementation which was developed before
+ adding the common infrastructure for handling hardlockup detectors.
+ It is always built. It does _not_ use the common command line
+ parameters and sysctl interface, except for
+ /proc/sys/kernel/nmi_watchdog.
config HAVE_HARDLOCKUP_DETECTOR_ARCH
bool
select HAVE_NMI_WATCHDOG
help
- The arch chooses to provide its own hardlockup detector, which is
- a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
- interfaces and parameters provided by hardlockup detector subsystem.
+ The arch provides its own hardlockup detector implementation instead
+ of the generic ones.
+
+ It uses the same command line parameters, and sysctl interface,
+ as the generic hardlockup detectors.
+
+ HAVE_NMI_WATCHDOG is selected to build the code shared with
+ the sparc64 specific implementation.
config HAVE_PERF_REGS
bool