Commit 61988e36 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

perf: Fix cgroup state vs ERROR 



While chasing down a missing perf_cgroup_event_disable() elsewhere,
Leo Yan found that both perf_put_aux_event() and
perf_remove_sibling_event() were also missing one.

Specifically, the rule is that events that switch to OFF,ERROR need to
call perf_cgroup_event_disable().

Unify the disable paths to ensure this.

Fixes: ab43762e ("perf: Allow normal events to output AUX data")
Fixes: 9f0c4fa1 ("perf/core: Add a new PERF_EV_CAP_SIBLING event capability")
Reported-by: default avatarLeo Yan <leo.yan@arm.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250605123343.GD35970@noisy.programming.kicks-ass.net
parent 4f6fc782

kernel/events/core.c

+30 −21
Original line number Diff line number Diff line
@@ -2149,8 +2149,9 @@ perf_aux_output_match(struct perf_event *event, struct perf_event *aux_event) 
}



static void put_event(struct perf_event *event);

static void event_sched_out(struct perf_event *event,

			    struct perf_event_context *ctx);

static void __event_disable(struct perf_event *event,

			    struct perf_event_context *ctx,

			    enum perf_event_state state);



static void perf_put_aux_event(struct perf_event *event)

{
@@ -2183,8 +2184,7 @@ static void perf_put_aux_event(struct perf_event *event) 
		 * state so that we don't try to schedule it again. Note

		 * that perf_event_enable() will clear the ERROR status.

		 */

		event_sched_out(iter, ctx);

		perf_event_set_state(event, PERF_EVENT_STATE_ERROR);

		__event_disable(iter, ctx, PERF_EVENT_STATE_ERROR);

	}

}
@@ -2242,18 +2242,6 @@ static inline struct list_head *get_event_list(struct perf_event *event) 
				    &event->pmu_ctx->flexible_active;

}



/*

 * Events that have PERF_EV_CAP_SIBLING require being part of a group and

 * cannot exist on their own, schedule them out and move them into the ERROR

 * state. Also see _perf_event_enable(), it will not be able to recover

 * this ERROR state.

 */

static inline void perf_remove_sibling_event(struct perf_event *event)

{

	event_sched_out(event, event->ctx);

	perf_event_set_state(event, PERF_EVENT_STATE_ERROR);

}



static void perf_group_detach(struct perf_event *event)

{

	struct perf_event *leader = event->group_leader;
@@ -2289,8 +2277,15 @@ static void perf_group_detach(struct perf_event *event) 
	 */

	list_for_each_entry_safe(sibling, tmp, &event->sibling_list, sibling_list) {



		/*

		 * Events that have PERF_EV_CAP_SIBLING require being part of

		 * a group and cannot exist on their own, schedule them out

		 * and move them into the ERROR state. Also see

		 * _perf_event_enable(), it will not be able to recover this

		 * ERROR state.

		 */

		if (sibling->event_caps & PERF_EV_CAP_SIBLING)

			perf_remove_sibling_event(sibling);

			__event_disable(sibling, ctx, PERF_EVENT_STATE_ERROR);



		sibling->group_leader = sibling;

		list_del_init(&sibling->sibling_list);
@@ -2562,6 +2557,15 @@ static void perf_remove_from_context(struct perf_event *event, unsigned long fla 
	event_function_call(event, __perf_remove_from_context, (void *)flags);

}



static void __event_disable(struct perf_event *event,

			    struct perf_event_context *ctx,

			    enum perf_event_state state)

{

	event_sched_out(event, ctx);

	perf_cgroup_event_disable(event, ctx);

	perf_event_set_state(event, state);

}



/*

 * Cross CPU call to disable a performance event

 */
@@ -2576,13 +2580,18 @@ static void __perf_event_disable(struct perf_event *event, 
	perf_pmu_disable(event->pmu_ctx->pmu);

	ctx_time_update_event(ctx, event);



	/*

	 * When disabling a group leader, the whole group becomes ineligible

	 * to run, so schedule out the full group.

	 */

	if (event == event->group_leader)

		group_sched_out(event, ctx);

	else

		event_sched_out(event, ctx);



	perf_event_set_state(event, PERF_EVENT_STATE_OFF);

	perf_cgroup_event_disable(event, ctx);

	/*

	 * But only mark the leader OFF; the siblings will remain

	 * INACTIVE.

	 */

	__event_disable(event, ctx, PERF_EVENT_STATE_OFF);



	perf_pmu_enable(event->pmu_ctx->pmu);

}