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Commit d0b6e0a8 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
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watchdog/hardlockup: Provide interface to stop/restart perf events 



Provide an interface to stop and restart perf NMI watchdog events on all
CPUs. This is only usable during init and especially for handling the perf
HT bug on Intel machines. It's safe to use it this way as nothing can
start/stop the NMI watchdog in parallel.

Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarDon Zickus <dzickus@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Link: http://lkml.kernel.org/r/20170912194146.167649596@linutronix.de


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 46c1e79f

include/linux/nmi.h

+4 −0
Original line number Diff line number Diff line
@@ -75,7 +75,11 @@ static inline void hardlockup_detector_disable(void) {} 


#if defined(CONFIG_HARDLOCKUP_DETECTOR_PERF)

extern void arch_touch_nmi_watchdog(void);

extern void hardlockup_detector_perf_stop(void);

extern void hardlockup_detector_perf_restart(void);

#else

static inline void hardlockup_detector_perf_stop(void) { }

static inline void hardlockup_detector_perf_restart(void) { }

#if !defined(CONFIG_HAVE_NMI_WATCHDOG)

static inline void arch_touch_nmi_watchdog(void) {}

#endif

kernel/watchdog_hld.c

+41 −0
Original line number Diff line number Diff line
@@ -261,3 +261,44 @@ void watchdog_nmi_disable(unsigned int cpu) 
			firstcpu_err = 0;

	}

}



/**

 * hardlockup_detector_perf_stop - Globally stop watchdog events

 *

 * Special interface for x86 to handle the perf HT bug.

 */

void __init hardlockup_detector_perf_stop(void)

{

	int cpu;



	lockdep_assert_cpus_held();



	for_each_online_cpu(cpu) {

		struct perf_event *event = per_cpu(watchdog_ev, cpu);



		if (event)

			perf_event_disable(event);

	}

}



/**

 * hardlockup_detector_perf_restart - Globally restart watchdog events

 *

 * Special interface for x86 to handle the perf HT bug.

 */

void __init hardlockup_detector_perf_restart(void)

{

	int cpu;



	lockdep_assert_cpus_held();



	if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED))

		return;



	for_each_online_cpu(cpu) {

		struct perf_event *event = per_cpu(watchdog_ev, cpu);



		if (event)

			perf_event_enable(event);

	}

}