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Commit 542e72fc authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf: Fix reading in perf_event_read() 



It is quite possible for the event to have been disabled between
perf_event_read() sending the IPI and the CPU servicing the IPI and
calling __perf_event_read(), hence revalidate the state.

Reported-by: default avatarStephane Eranian <eranian@google.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 9ffdc6c3

kernel/perf_event.c

+4 −3
Original line number Diff line number Diff line
@@ -1901,11 +1901,12 @@ static void __perf_event_read(void *info) 
		return;



	raw_spin_lock(&ctx->lock);

	if (ctx->is_active)

		update_context_time(ctx);

	update_event_times(event);

	raw_spin_unlock(&ctx->lock);



	if (event->state == PERF_EVENT_STATE_ACTIVE)

		event->pmu->read(event);

	raw_spin_unlock(&ctx->lock);

}



static inline u64 perf_event_count(struct perf_event *event)