diff options
| author | Will Deacon | 2011-12-13 20:40:45 +0100 |
|---|---|---|
| committer | Ingo Molnar | 2011-12-14 08:44:53 +0100 |
| commit | 44b7f4b98d8877e2a4427f2a2f2e42ae8227a58f (patch) | |
| tree | 929c7c5c177fa072216445de276592843ebae4d8 /kernel | |
| parent | 373da0a2a33018d560afcb2c77f8842985d79594 (diff) | |
perf events: Fix ring_buffer_wakeup() brown paperbag bug
Commit 10c6db11 ("perf: Fix loss of notification with multi-event")
seems to unconditionally dereference event->rb in the wakeup handler,
this is wrong, there might not be a buffer attached.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20111213152651.GP20297@mudshark.cambridge.arm.com
[ minor edits ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/events/core.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index d3b9df5962c2..58690af323e4 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3558,9 +3558,13 @@ static void ring_buffer_wakeup(struct perf_event *event) rcu_read_lock(); rb = rcu_dereference(event->rb); - list_for_each_entry_rcu(event, &rb->event_list, rb_entry) { + if (!rb) + goto unlock; + + list_for_each_entry_rcu(event, &rb->event_list, rb_entry) wake_up_all(&event->waitq); - } + +unlock: rcu_read_unlock(); } |