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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2010-10-15 11:40:29 +0200
committerIngo Molnar <mingo@elte.hu>2010-10-18 19:58:51 +0200
commit74c3337c2fc6389d3a57a622a936036b6db6b2e8 (patch)
treed87232b7cc19eef0f1fe0a0bb167868513819b31 /kernel/perf_event.c
parente360adbe29241a0194e10e20595360dd7b98a2b3 (diff)
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perf: Fix group moving
Matt found we trigger the WARN_ON_ONCE() in perf_group_attach() when we take the move_group path in perf_event_open(). Since we cannot de-construct the group (we rely on it to move the events), we have to simply ignore the double attach. The group state is context invariant and doesn't need changing. Reported-by: Matt Fleming <matt@console-pimps.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1287135757.29097.1368.camel@twins> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/perf_event.c')
-rw-r--r--kernel/perf_event.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 99b9700e74d0..346dc0e35a0a 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -315,7 +315,12 @@ static void perf_group_attach(struct perf_event *event)
{
struct perf_event *group_leader = event->group_leader;
- WARN_ON_ONCE(event->attach_state & PERF_ATTACH_GROUP);
+ /*
+ * We can have double attach due to group movement in perf_event_open.
+ */
+ if (event->attach_state & PERF_ATTACH_GROUP)
+ return;
+
event->attach_state |= PERF_ATTACH_GROUP;
if (group_leader == event)