diff options
| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2011-01-26 15:38:35 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2011-02-03 12:15:46 +0100 |
| commit | 542e72fc90f5ed9eecb574f80f70868c7f296093 (patch) | |
| tree | b42abb2d44ed771759eee63ce00378df02d689ca /kernel | |
| parent | 9ffdc6c37df131f89d52001e0ef03091b158826f (diff) | |
| download | lwn-542e72fc90f5ed9eecb574f80f70868c7f296093.tar.gz lwn-542e72fc90f5ed9eecb574f80f70868c7f296093.zip | |
perf: Fix reading in perf_event_read()
It is quite possible for the event to have been disabled between
perf_event_read() sending the IPI and the CPU servicing the IPI and
calling __perf_event_read(), hence revalidate the state.
Reported-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/perf_event.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 852ae8c66502..999835b6112b 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -1901,11 +1901,12 @@ static void __perf_event_read(void *info) return; raw_spin_lock(&ctx->lock); - update_context_time(ctx); + if (ctx->is_active) + update_context_time(ctx); update_event_times(event); + if (event->state == PERF_EVENT_STATE_ACTIVE) + event->pmu->read(event); raw_spin_unlock(&ctx->lock); - - event->pmu->read(event); } static inline u64 perf_event_count(struct perf_event *event) |