perf: Fix enable_on_exec for sibling events

Deng-Cheng Zhu reported that sibling events that were created disabled
with enable_on_exec would never get enabled. Iterate all events
instead of the group lists.
Reported-by: NDeng-Cheng Zhu <dczhu@mips.com>
Tested-by: NDeng-Cheng Zhu <dczhu@mips.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1322048382.14799.41.camel@twinsSigned-off-by: NIngo Molnar <mingo@elte.hu>

kernel/events/core.c

@@ -2497,13 +2497,7 @@ static void perf_event_enable_on_exec(struct perf_event_context *ctx)
 	raw_spin_lock(&ctx->lock);
 	task_ctx_sched_out(ctx);
 
-	list_for_each_entry(event, &ctx->pinned_groups, group_entry) {
-		ret = event_enable_on_exec(event, ctx);
-		if (ret)
-			enabled = 1;
-	}
-
-	list_for_each_entry(event, &ctx->flexible_groups, group_entry) {
+	list_for_each_entry(event, &ctx->event_list, event_entry) {
 		ret = event_enable_on_exec(event, ctx);
 		if (ret)
 			enabled = 1;