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Commit 95cf59ea authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf: Fix perf_cgroup_switch for sw-events 



Jiri reported that he could trigger the WARN_ON_ONCE() in
perf_cgroup_switch() using sw-events. This is because sw-events share
a cpuctx with multiple PMUs.

Use the ->unique_pmu pointer to limit the pmu iteration to unique
cpuctx instances.

Reported-and-Tested-by: default avatarJiri Olsa <jolsa@redhat.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-so7wi2zf3jjzrwcutm2mkz0j@git.kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 3f1f3320

kernel/events/core.c

+6 −3
Original line number Diff line number Diff line
@@ -372,6 +372,8 @@ void perf_cgroup_switch(struct task_struct *task, int mode) 


	list_for_each_entry_rcu(pmu, &pmus, entry) {

		cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);

		if (cpuctx->unique_pmu != pmu)

			continue; /* ensure we process each cpuctx once */



		/*

		 * perf_cgroup_events says at least one
@@ -395,9 +397,10 @@ void perf_cgroup_switch(struct task_struct *task, int mode) 


			if (mode & PERF_CGROUP_SWIN) {

				WARN_ON_ONCE(cpuctx->cgrp);

				/* set cgrp before ctxsw in to

				 * allow event_filter_match() to not

				 * have to pass task around

				/*

				 * set cgrp before ctxsw in to allow

				 * event_filter_match() to not have to pass

				 * task around

				 */

				cpuctx->cgrp = perf_cgroup_from_task(task);

				cpu_ctx_sched_in(cpuctx, EVENT_ALL, task);