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Subject[PATCH] [263/275] perf: Fix tear-down of inherited group events
Date
2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Peter Zijlstra <a.p.zijlstra@chello.nl>

[ upstream commit 38b435b16c36b0d863efcf3f07b34a6fac9873fd ]

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-and-tested-by: Vince Weaver <vweaver1@eecs.utk.edu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: <stable@kernel.org> # .35+
LKML-Reference: <1300196470.2203.61.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

---
kernel/perf_event.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

Index: linux-2.6.35.y/kernel/perf_event.c
===================================================================
--- linux-2.6.35.y.orig/kernel/perf_event.c 2011-03-29 23:03:03.000000000 -0700
+++ linux-2.6.35.y/kernel/perf_event.c 2011-03-29 23:27:02.487390526 -0700
@@ -5401,17 +5401,20 @@
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_event_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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