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Commit 70a01657 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf: Fix cgroup scheduling in perf_enable_on_exec() 



There is a comment that states that perf_event_context_sched_in() will
also switch in the cgroup events, I cannot find it does so. Therefore
all the resulting logic goes out the window too.

Clean that up.

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 7e41d177

kernel/events/core.c

+7 −24
Original line number Diff line number Diff line
@@ -579,12 +579,6 @@ static inline void perf_cgroup_sched_out(struct task_struct *task, 
	 * we are holding the rcu lock

	 */

	cgrp1 = perf_cgroup_from_task(task, NULL);



	/*

	 * next is NULL when called from perf_event_enable_on_exec()

	 * that will systematically cause a cgroup_switch()

	 */

	if (next)

	cgrp2 = perf_cgroup_from_task(next, NULL);



	/*
@@ -611,8 +605,6 @@ static inline void perf_cgroup_sched_in(struct task_struct *prev, 
	 * we are holding the rcu lock

	 */

	cgrp1 = perf_cgroup_from_task(task, NULL);



	/* prev can never be NULL */

	cgrp2 = perf_cgroup_from_task(prev, NULL);



	/*
@@ -1450,11 +1442,14 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx) 


	if (is_cgroup_event(event)) {

		ctx->nr_cgroups--;

		/*

		 * Because cgroup events are always per-cpu events, this will

		 * always be called from the right CPU.

		 */

		cpuctx = __get_cpu_context(ctx);

		/*

		 * if there are no more cgroup events

		 * then cler cgrp to avoid stale pointer

		 * in update_cgrp_time_from_cpuctx()

		 * If there are no more cgroup events then clear cgrp to avoid

		 * stale pointer in update_cgrp_time_from_cpuctx().

		 */

		if (!ctx->nr_cgroups)

			cpuctx->cgrp = NULL;
@@ -3118,15 +3113,6 @@ static void perf_event_enable_on_exec(int ctxn) 
	if (!ctx || !ctx->nr_events)

		goto out;



	/*

	 * We must ctxsw out cgroup events to avoid conflict

	 * when invoking perf_task_event_sched_in() later on

	 * in this function. Otherwise we end up trying to

	 * ctxswin cgroup events which are already scheduled

	 * in.

	 */

	perf_cgroup_sched_out(current, NULL);



	raw_spin_lock(&ctx->lock);

	task_ctx_sched_out(ctx);
@@ -3144,9 +3130,6 @@ static void perf_event_enable_on_exec(int ctxn) 


	raw_spin_unlock(&ctx->lock);



	/*

	 * Also calls ctxswin for cgroup events, if any:

	 */

	perf_event_context_sched_in(ctx, ctx->task);

out:

	local_irq_restore(flags);