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SubjectRe: [PATCH] perf cgroups: Fix perf_cgroup_switch schedule in warning
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On Tue, 2012-10-02 at 13:42 +0200, Jiri Olsa wrote:
> +++ b/kernel/events/core.c
> @@ -394,7 +394,8 @@ void perf_cgroup_switch(struct task_struct *task, int mode)
> }
>
> if (mode & PERF_CGROUP_SWIN) {
> - WARN_ON_ONCE(cpuctx->cgrp);
> + WARN_ON_ONCE(cpuctx->cgrp && !cpuctx->ctx.is_active);
> +
> /* set cgrp before ctxsw in to
> * allow event_filter_match() to not
> * have to pass task around

OK, like you mentioned this is the result of multiple PMU being able to
share a cpuctx, shouldn't we in that case avoid the second loop over the
cpuctx as a whole?

Would something like the below do? IIRC I introduced that active_pmu for
exactly such reasons..

---
kernel/events/core.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 7b9df35..e98f014 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -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->active_pmu != pmu)
+ continue;

/*
* perf_cgroup_events says at least one


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