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Subject[PATCH] perf: Fix tear-down of inherited group events
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Subject: perf: Fix tear-down of inherited group events
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Tue Mar 15 14:37:10 CET 2011

When destroying inherited events, we need to destroy groups too,
otherwise the event iteration in perf_event_exit_task_context() will
miss group siblings and we leak events with all the consequences.

Reported-by: Vince Weaver <vweaver1@eecs.utk.edu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: stable@kernel.org # .35+
---
kernel/perf_event.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
Index: linux-2.6/kernel/perf_event.c
===================================================================
--- linux-2.6.orig/kernel/perf_event.c
+++ linux-2.6/kernel/perf_event.c
@@ -6722,17 +6722,20 @@ __perf_event_exit_task(struct perf_event
struct perf_event_context *child_ctx,
struct task_struct *child)
{
- struct perf_event *parent_event;
+ if (child_event->parent) {
+ raw_spin_lock_irq(&child_ctx->lock);
+ perf_group_detach(child_event);
+ raw_spin_unlock_irq(&child_ctx->lock);
+ }

perf_remove_from_context(child_event);

- parent_event = child_event->parent;
/*
- * It can happen that parent exits first, and has events
+ * It can happen that the parent exits first, and has events
* that are still around due to the child reference. These
- * events need to be zapped - but otherwise linger.
+ * events need to be zapped.
*/
- if (parent_event) {
+ if (child_event->parent) {
sync_child_event(child_event, child);
free_event(child_event);
}


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