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authorWill Deacon <will.deacon@arm.com>2011-12-13 20:40:45 +0100
committerIngo Molnar <mingo@elte.hu>2011-12-14 08:44:53 +0100
commit44b7f4b98d8877e2a4427f2a2f2e42ae8227a58f (patch)
tree929c7c5c177fa072216445de276592843ebae4d8 /kernel
parent373da0a2a33018d560afcb2c77f8842985d79594 (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.c8
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();
}