perf: Fix perf_event_for_each() to use sibling

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@ellerman.id.au>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1334109253-31329-1-git-send-email-michael@ellerman.id.au
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 8141883..6fb4a36 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3326,7 +3326,7 @@ static void perf_event_for_each(struct perf_event *event,
        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);
        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);
 }
 
        mutex_unlock(&ctx->mutex);
 }