Commit 9ec272c5 authored by Douglas Anderson's avatar Douglas Anderson Committed by Andrew Morton
Browse files

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

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: a994a314 ("watchdog/hardlockup/perf: Implement init time detection of perf")
Signed-off-by: default avatarDouglas Anderson <dianders@chromium.org>
Reported-by: default avatarPetr Mladek <pmladek@suse.com>
Closes: https://lore.kernel.org/r/ZHCn4hNxFpY5-9Ki@alley


Reviewed-by: default avatarPetr 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: default avatarAndrew Morton <akpm@linux-foundation.org>
parent a94181ec

include/linux/nmi.h

+0 −6
Original line number Diff line number Diff line
@@ -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);

kernel/watchdog.c

+20 −10
Original line number Diff line number Diff line
@@ -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();

}