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Commit 2b8988c9 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf: Fix time locking 



Most sites updating ctx->time and event times do so under
ctx->lock, make sure they all do.

This was made possible by removing the __perf_event_read() call
from __perf_event_sync_stat(), which already had this lock
taken.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20091120212509.102316434@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 58e5ad1d

kernel/perf_event.c

+9 −0
Original line number Original line Diff line number Diff line
@@ -1526,8 +1526,11 @@ static void __perf_event_read(void *info) 
	if (ctx->task && cpuctx->task_ctx != ctx)

	if (ctx->task && cpuctx->task_ctx != ctx)

		return;

		return;





	spin_lock(&ctx->lock);

	update_context_time(ctx);

	update_context_time(ctx);

	update_event_times(event);

	update_event_times(event);

	spin_unlock(&ctx->lock);



	event->pmu->read(event);

	event->pmu->read(event);

}

}
@@ -1541,7 +1544,13 @@ static u64 perf_event_read(struct perf_event *event) 
		smp_call_function_single(event->oncpu,

		smp_call_function_single(event->oncpu,

					 __perf_event_read, event, 1);

					 __perf_event_read, event, 1);

	} else if (event->state == PERF_EVENT_STATE_INACTIVE) {

	} else if (event->state == PERF_EVENT_STATE_INACTIVE) {

		struct perf_event_context *ctx = event->ctx;

		unsigned long flags;



		spin_lock_irqsave(&ctx->lock, flags);

		update_context_time(ctx);

		update_event_times(event);

		update_event_times(event);

		spin_unlock_irqrestore(&ctx->lock, flags);

	}

	}





	return atomic64_read(&event->count);

	return atomic64_read(&event->count);