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watchdog/hardlockup: keep kernel.nmi_watchdog sysctl as 0444 if probe fails

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Patch series "watchdog: Cleanup / fixes after buddy series v5 reviews".

This patch series attempts to finish resolving the feedback received
from Petr Mladek on the v5 series I posted.

Probably the only thing that wasn't fully as clean as Petr requested was
the Kconfig stuff.  I couldn't find a better way to express it without a
more major overhaul.  In the very least, I renamed "NON_ARCH" to
"PERF_OR_BUDDY" in the hopes that will make it marginally better.

Nothing in this series is terribly critical and even the bugfixes are
small.  However, it does cleanup a few things that were pointed out in
review.


This patch (of 10):

The permissions for the kernel.nmi_watchdog sysctl have always been set at
compile time despite the fact that a watchdog can fail to probe.  Let's
fix this and set the permissions based on whether the hardlockup detector
actually probed.

Link: https://lkml.kernel.org/r/20230527014153.2793931-1-dianders@chromium.org
Link: https://lkml.kernel.org/r/20230526184139.1.I0d75971cc52a7283f495aac0bd5c3041aadc734e@changeid
Fixes: a994a3147e ("watchdog/hardlockup/perf: Implement init time detection of perf")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reported-by: Petr Mladek <pmladek@suse.com>
Closes: https://lore.kernel.org/r/ZHCn4hNxFpY5-9Ki@alley
Reviewed-by: Petr Mladek <pmladek@suse.com>
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:
Douglas Anderson 2023-05-26 18:41:31 -07:00 committed by Andrew Morton
parent a94181ec06
commit 9ec272c586
2 changed files with 20 additions and 16 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
include/linux/nmi.h
View file

@ -95,12 +95,6 @@ void watchdog_hardlockup_check(unsigned int cpu, struct pt_regs *regs);
static inline void arch_touch_nmi_watchdog(void) { }
#endif
#if defined(CONFIG_HAVE_NMI_WATCHDOG) || defined(CONFIG_HARDLOCKUP_DETECTOR)
# define NMI_WATCHDOG_SYSCTL_PERM 0644
#else
# define NMI_WATCHDOG_SYSCTL_PERM 0444
#endif
#if defined(CONFIG_HARDLOCKUP_DETECTOR_PERF)
extern void hardlockup_detector_perf_stop(void);
extern void hardlockup_detector_perf_restart(void);

30
kernel/watchdog.c
View file

@ -880,15 +880,6 @@ static struct ctl_table watchdog_sysctls[] = {
.extra1 = SYSCTL_ZERO,
.extra2 = (void *)&sixty,
},
{
.procname = "nmi_watchdog",
.data = &watchdog_hardlockup_user_enabled,
.maxlen = sizeof(int),
.mode = NMI_WATCHDOG_SYSCTL_PERM,
.proc_handler = proc_nmi_watchdog,
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE,
},
{
.procname = "watchdog_cpumask",
.data = &watchdog_cpumask_bits,
@ -952,10 +943,28 @@ static struct ctl_table watchdog_sysctls[] = {
{}
};
static struct ctl_table watchdog_hardlockup_sysctl[] = {
{
.procname = "nmi_watchdog",
.data = &watchdog_hardlockup_user_enabled,
.maxlen = sizeof(int),
.mode = 0444,
.proc_handler = proc_nmi_watchdog,
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE,
},
{}
};
static void __init watchdog_sysctl_init(void)
{
register_sysctl_init("kernel", watchdog_sysctls);
if (watchdog_hardlockup_available)
watchdog_hardlockup_sysctl[0].mode = 0644;
register_sysctl_init("kernel", watchdog_hardlockup_sysctl);
}
#else
#define watchdog_sysctl_init() do { } while (0)
#endif /* CONFIG_SYSCTL */
@ -1011,6 +1020,8 @@ static int __init lockup_detector_check(void)
/* Make sure no work is pending. */
flush_work(&detector_work);
watchdog_sysctl_init();
return 0;
}
@ -1030,5 +1041,4 @@ void __init lockup_detector_init(void)
allow_lockup_detector_init_retry = true;
lockup_detector_setup();
watchdog_sysctl_init();
}