Commit ff5860f5 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

perf: Ensure swevent hrtimer is properly destroyed 



With the change to hrtimer_try_to_cancel() in
perf_swevent_cancel_hrtimer() it appears possible for the hrtimer to
still be active by the time the event gets freed.

Make sure the event does a full hrtimer_cancel() on the free path by
installing a perf_event::destroy handler.

Fixes: eb3182ef ("perf/core: Fix system hang caused by cpu-clock usage")
Reported-by: default avatarCyberUnicorns <a101e_iotvul@163.com>
Tested-by: default avatarCyberUnicorns <a101e_iotvul@163.com>
Debugged-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
parent 9ace4753

kernel/events/core.c

+6 −0
Original line number Diff line number Diff line
@@ -11906,6 +11906,11 @@ static void perf_swevent_cancel_hrtimer(struct perf_event *event) 
	}

}



static void perf_swevent_destroy_hrtimer(struct perf_event *event)

{

	hrtimer_cancel(&event->hw.hrtimer);

}



static void perf_swevent_init_hrtimer(struct perf_event *event)

{

	struct hw_perf_event *hwc = &event->hw;
@@ -11914,6 +11919,7 @@ static void perf_swevent_init_hrtimer(struct perf_event *event) 
		return;



	hrtimer_setup(&hwc->hrtimer, perf_swevent_hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);

	event->destroy = perf_swevent_destroy_hrtimer;



	/*

	 * Since hrtimers have a fixed rate, we can do a static freq->period