[PATCH 3.2 110/126] perf: Fix perf_event_for_each() to use sibling

[Ben Hutchings]

3.2.85-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Michael Ellerman <michael@xxxxxxxxxxxxxx>

commit 724b6daa13e100067c30cfc4d1ad06629609dc4e upstream.

In perf_event_for_each() we call a function on an event, and then
iterate over the siblings of the event.

However we don't call the function on the siblings, we call it
repeatedly on the original event - it seems "obvious" that we should
be calling it with sibling as the argument.

It looks like this broke in commit 75f937f24bd9 ("Fix ctx->mutex
vs counter->mutex inversion").

The only effect of the bug is that the PERF_IOC_FLAG_GROUP parameter
to the ioctls doesn't work.

Signed-off-by: Michael Ellerman <michael@xxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1334109253-31329-1-git-send-email-michael@xxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 kernel/events/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3326,7 +3326,7 @@ static void perf_event_for_each(struct p
 	perf_event_for_each_child(event, func);
 	func(event);
 	list_for_each_entry(sibling, &event->sibling_list, group_entry)
-		perf_event_for_each_child(event, func);
+		perf_event_for_each_child(sibling, func);
 	mutex_unlock(&ctx->mutex);
 }