diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2014-02-24 12:06:12 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2014-02-27 12:38:03 +0100 |
| commit | e3703f8cdfcf39c25c4338c3ad8e68891cca3731 (patch) | |
| tree | b4fc6439f43eca37c954ce4d5d2848279b115b99 | |
| parent | 26e61e8939b1fe8729572dabe9a9e97d930dd4f6 (diff) | |
perf: Fix hotplug splat
Drew Richardson reported that he could make the kernel go *boom* when hotplugging
while having perf events active.
It turned out that when you have a group event, the code in
__perf_event_exit_context() fails to remove the group siblings from
the context.
We then proceed with destroying and freeing the event, and when you
re-plug the CPU and try and add another event to that CPU, things go
*boom* because you've still got dead entries there.
Reported-by: Drew Richardson <drew.richardson@arm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/n/tip-k6v5wundvusvcseqj1si0oz0@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | kernel/events/core.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 56003c6edfd3..fa0b2d4ad83c 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7856,14 +7856,14 @@ static void perf_pmu_rotate_stop(struct pmu *pmu) static void __perf_event_exit_context(void *__info) { struct perf_event_context *ctx = __info; - struct perf_event *event, *tmp; + struct perf_event *event; perf_pmu_rotate_stop(ctx->pmu); - list_for_each_entry_safe(event, tmp, &ctx->pinned_groups, group_entry) - __perf_remove_from_context(event); - list_for_each_entry_safe(event, tmp, &ctx->flexible_groups, group_entry) + rcu_read_lock(); + list_for_each_entry_rcu(event, &ctx->event_list, event_entry) __perf_remove_from_context(event); + rcu_read_unlock(); } static void perf_event_exit_cpu_context(int cpu) @@ -7887,11 +7887,11 @@ static void perf_event_exit_cpu(int cpu) { struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu); + perf_event_exit_cpu_context(cpu); + mutex_lock(&swhash->hlist_mutex); swevent_hlist_release(swhash); mutex_unlock(&swhash->hlist_mutex); - - perf_event_exit_cpu_context(cpu); } #else static inline void perf_event_exit_cpu(int cpu) { } |