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Commit 4fd38e45 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf: Fix exit() vs PERF_FORMAT_GROUP 



Both Stephane and Corey reported that PERF_FORMAT_GROUP didn't work
as expected if the task the counters were attached to quit before
the read() call.

The cause is that we unconditionally destroy the grouping when we
remove counters from their context. Fix this by only doing this when
we free the counter itself.

Reported-by: default avatarCorey Ashford <cjashfor@linux.vnet.ibm.com>
Reported-by: default avatarStephane Eranian <eranian@google.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1273160566.5605.404.camel@twins>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 722154e4

include/linux/perf_event.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -522,6 +522,7 @@ struct pmu { 
 * enum perf_event_active_state - the states of a event

 * enum perf_event_active_state - the states of a event

 */

 */

enum perf_event_active_state {

enum perf_event_active_state {

	PERF_EVENT_STATE_FREE		= -3,

	PERF_EVENT_STATE_ERROR		= -2,

	PERF_EVENT_STATE_ERROR		= -2,

	PERF_EVENT_STATE_OFF		= -1,

	PERF_EVENT_STATE_OFF		= -1,

	PERF_EVENT_STATE_INACTIVE	=  0,

	PERF_EVENT_STATE_INACTIVE	=  0,

kernel/perf_event.c

+5 −0
Original line number Original line Diff line number Diff line
@@ -341,6 +341,9 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx) 
	if (event->state > PERF_EVENT_STATE_OFF)

	if (event->state > PERF_EVENT_STATE_OFF)

		event->state = PERF_EVENT_STATE_OFF;

		event->state = PERF_EVENT_STATE_OFF;





	if (event->state > PERF_EVENT_STATE_FREE)

		return;



	/*

	/*

	 * If this was a group event with sibling events then

	 * If this was a group event with sibling events then

	 * upgrade the siblings to singleton events by adding them

	 * upgrade the siblings to singleton events by adding them
@@ -1856,6 +1859,8 @@ int perf_event_release_kernel(struct perf_event *event) 
{

{

	struct perf_event_context *ctx = event->ctx;

	struct perf_event_context *ctx = event->ctx;





	event->state = PERF_EVENT_STATE_FREE;



	WARN_ON_ONCE(ctx->parent_ctx);

	WARN_ON_ONCE(ctx->parent_ctx);

	mutex_lock(&ctx->mutex);

	mutex_lock(&ctx->mutex);

	perf_event_remove_from_context(event);

	perf_event_remove_from_context(event);