| From | Ben Hutchings <> | Date | Mon, 21 Oct 2013 09:46:28 +0100 | Subject | [PATCH 3.2 133/149] perf: Fix perf_cgroup_switch for sw-events |
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3.2.52-rc1 review patch. If anyone has any objections, please let me know.
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From: Peter Zijlstra <a.p.zijlstra@chello.nl>
commit 95cf59ea72331d0093010543b8951bb43f262cac upstream.
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: Jiri Olsa <jolsa@redhat.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-so7wi2zf3jjzrwcutm2mkz0j@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- kernel/events/core.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
--- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -360,6 +360,8 @@ void perf_cgroup_switch(struct task_stru 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 @@ -383,9 +385,10 @@ void perf_cgroup_switch(struct task_stru 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);
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