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| author | Peter Zijlstra <peterz@infradead.org> | 2014-02-24 12:06:12 +0100 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2014-04-02 00:58:56 +0100 |
| commit | 7b80b8d77f13e7d8a88179a208b839b31a9f667d (patch) | |
| tree | df13e1504d2705a9f6c1454b88dadf7ba7743b12 | |
| parent | 43e2f50d5845b7bc29e3ccf464144c66d2eab7da (diff) | |
| download | lwn-7b80b8d77f13e7d8a88179a208b839b31a9f667d.tar.gz lwn-7b80b8d77f13e7d8a88179a208b839b31a9f667d.zip | |
perf: Fix hotplug splat
commit e3703f8cdfcf39c25c4338c3ad8e68891cca3731 upstream.
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>
Link: http://lkml.kernel.org/n/tip-k6v5wundvusvcseqj1si0oz0@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -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 83d5621b7d90..b15b4f75131d 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7101,14 +7101,14 @@ 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) @@ -7132,11 +7132,11 @@ 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) { } |