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Commit f67218c3 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf_events: Fix __perf_event_exit_task() vs. update_event_times() locking 



Move the update_event_times() call in __perf_event_exit_task()
into list_del_event() because that holds the proper lock
(ctx->lock) and seems a more natural place to do the last time
update.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091123103819.842455480@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 5e942bb3

kernel/perf_event.c

+39 −39
Original line number Diff line number Diff line
@@ -246,6 +246,44 @@ static void perf_unpin_context(struct perf_event_context *ctx) 
	put_ctx(ctx);

}



static inline u64 perf_clock(void)

{

	return cpu_clock(smp_processor_id());

}



/*

 * Update the record of the current time in a context.

 */

static void update_context_time(struct perf_event_context *ctx)

{

	u64 now = perf_clock();



	ctx->time += now - ctx->timestamp;

	ctx->timestamp = now;

}



/*

 * Update the total_time_enabled and total_time_running fields for a event.

 */

static void update_event_times(struct perf_event *event)

{

	struct perf_event_context *ctx = event->ctx;

	u64 run_end;



	if (event->state < PERF_EVENT_STATE_INACTIVE ||

	    event->group_leader->state < PERF_EVENT_STATE_INACTIVE)

		return;



	event->total_time_enabled = ctx->time - event->tstamp_enabled;



	if (event->state == PERF_EVENT_STATE_INACTIVE)

		run_end = event->tstamp_stopped;

	else

		run_end = ctx->time;



	event->total_time_running = run_end - event->tstamp_running;

}



/*

 * Add a event from the lists for its context.

 * Must be called with ctx->mutex and ctx->lock held.
@@ -294,6 +332,7 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx) 
	if (event->group_leader != event)

		event->group_leader->nr_siblings--;



	update_event_times(event);

	event->state = PERF_EVENT_STATE_OFF;



	/*
@@ -454,44 +493,6 @@ retry: 
	spin_unlock_irq(&ctx->lock);

}



static inline u64 perf_clock(void)

{

	return cpu_clock(smp_processor_id());

}



/*

 * Update the record of the current time in a context.

 */

static void update_context_time(struct perf_event_context *ctx)

{

	u64 now = perf_clock();



	ctx->time += now - ctx->timestamp;

	ctx->timestamp = now;

}



/*

 * Update the total_time_enabled and total_time_running fields for a event.

 */

static void update_event_times(struct perf_event *event)

{

	struct perf_event_context *ctx = event->ctx;

	u64 run_end;



	if (event->state < PERF_EVENT_STATE_INACTIVE ||

	    event->group_leader->state < PERF_EVENT_STATE_INACTIVE)

		return;



	event->total_time_enabled = ctx->time - event->tstamp_enabled;



	if (event->state == PERF_EVENT_STATE_INACTIVE)

		run_end = event->tstamp_stopped;

	else

		run_end = ctx->time;



	event->total_time_running = run_end - event->tstamp_running;

}



/*

 * Update total_time_enabled and total_time_running for all events in a group.

 */
@@ -4931,7 +4932,6 @@ __perf_event_exit_task(struct perf_event *child_event, 
{

	struct perf_event *parent_event;



	update_event_times(child_event);

	perf_event_remove_from_context(child_event);



	parent_event = child_event->parent;