[PATCH] [263/275] perf: Fix tear-down of inherited group events

[Andi Kleen]

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

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

[ 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@xxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxx> # .35+
LKML-Reference: <1300196470.2203.61.camel@twins>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>

---
 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);
 	}
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/