Commit c277443c authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf: Stop all counters on reboot 



Use the reboot notifier to detach all running counters on reboot, this
solves a problem with kexec where the new kernel doesn't expect
running counters (rightly so).

It will however decrease the coverage of the NMI watchdog. Making a
kexec specific reboot notifier callback would be best, however that
would require touching all notifier callback handlers as they are not
properly structured to deal with new state.

As a compromise, place the perf reboot notifier at the very last
position in the list.

Reported-by: default avatarYinghai Lu <yinghai@kernel.org>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Don Zickus <dzickus@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent c079c791

kernel/perf_event.c

+23 −1
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
#include <linux/dcache.h>

#include <linux/percpu.h>

#include <linux/ptrace.h>

#include <linux/reboot.h>

#include <linux/vmstat.h>

#include <linux/vmalloc.h>

#include <linux/hardirq.h>
@@ -6429,7 +6430,7 @@ static void __cpuinit perf_event_init_cpu(int cpu) 
	mutex_unlock(&swhash->hlist_mutex);

}



#ifdef CONFIG_HOTPLUG_CPU

#if defined CONFIG_HOTPLUG_CPU || defined CONFIG_KEXEC

static void perf_pmu_rotate_stop(struct pmu *pmu)

{

	struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
@@ -6483,6 +6484,26 @@ static void perf_event_exit_cpu(int cpu) 
static inline void perf_event_exit_cpu(int cpu) { }

#endif



static int

perf_reboot(struct notifier_block *notifier, unsigned long val, void *v)

{

	int cpu;



	for_each_online_cpu(cpu)

		perf_event_exit_cpu(cpu);



	return NOTIFY_OK;

}



/*

 * Run the perf reboot notifier at the very last possible moment so that

 * the generic watchdog code runs as long as possible.

 */

static struct notifier_block perf_reboot_notifier = {

	.notifier_call = perf_reboot,

	.priority = INT_MIN,

};



static int __cpuinit

perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu)

{
@@ -6518,6 +6539,7 @@ void __init perf_event_init(void) 
	perf_pmu_register(&perf_task_clock);

	perf_tp_register();

	perf_cpu_notifier(perf_cpu_notify);

	register_reboot_notifier(&perf_reboot_notifier);



	ret = init_hw_breakpoint();

	WARN(ret, "hw_breakpoint initialization failed with: %d", ret);

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