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Commit aee7dbc4 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
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perf: Simplify/fix perf_event_enable() event scheduling 



Like perf_enable_on_exec(), perf_event_enable() event scheduling has problems
respecting the context hierarchy when trying to schedule events (for
example, it will try and add a pinned event without first removing
existing flexible events).

So simplify it by using the new ctx_resched() call which will DTRT.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 8833d0e2

kernel/events/core.c

+5 −26
Original line number Diff line number Diff line
@@ -2188,7 +2188,7 @@ static int __perf_event_enable(void *info) 
	struct perf_event_context *ctx = event->ctx;

	struct perf_event *leader = event->group_leader;

	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);

	int err;

	struct perf_event_context *task_ctx = cpuctx->task_ctx;



	/*

	 * There's a time window between 'ctx->is_active' check
@@ -2202,7 +2202,8 @@ static int __perf_event_enable(void *info) 
	if (!ctx->is_active)

		return -EINVAL;



	raw_spin_lock(&ctx->lock);

	perf_ctx_lock(cpuctx, task_ctx);

	WARN_ON_ONCE(&cpuctx->ctx != ctx && task_ctx != ctx);

	update_context_time(ctx);



	if (event->state >= PERF_EVENT_STATE_INACTIVE)
@@ -2228,32 +2229,10 @@ static int __perf_event_enable(void *info) 
	if (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE)

		goto unlock;



	if (!group_can_go_on(event, cpuctx, 1)) {

		err = -EEXIST;

	} else {

		if (event == leader)

			err = group_sched_in(event, cpuctx, ctx);

		else

			err = event_sched_in(event, cpuctx, ctx);

	}



	if (err) {

		/*

		 * If this event can't go on and it's part of a

		 * group, then the whole group has to come off.

		 */

		if (leader != event) {

			group_sched_out(leader, cpuctx, ctx);

			perf_mux_hrtimer_restart(cpuctx);

		}

		if (leader->attr.pinned) {

			update_group_times(leader);

			leader->state = PERF_EVENT_STATE_ERROR;

		}

	}

	ctx_resched(cpuctx, task_ctx);



unlock:

	raw_spin_unlock(&ctx->lock);

	perf_ctx_unlock(cpuctx, task_ctx);



	return 0;

}