[PATCH v2] perf_counter: cleanup for __perf_event_sched_in()

[Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>]

It must be a group leader if event->attr.pinned is "1"

Changlog:
Use WARN_ON_ONCE() instead of BUG_ON() as Paul Mackerras's suggestion

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
 kernel/perf_event.c |   11 +++++------
 1 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 76ac4db..dc3221b 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -1258,12 +1258,11 @@ __perf_event_sched_in(struct perf_event_context *ctx,
 		if (event->cpu != -1 && event->cpu != cpu)
 			continue;
 
-		if (event != event->group_leader)
-			event_sched_in(event, cpuctx, ctx, cpu);
-		else {
-			if (group_can_go_on(event, cpuctx, 1))
-				group_sched_in(event, cpuctx, ctx, cpu);
-		}
+		/* Only a group leader can be pinned */
+		WARN_ON_ONCE(event != event->group_leader);
+
+		if (group_can_go_on(event, cpuctx, 1))
+			group_sched_in(event, cpuctx, ctx, cpu);
 
 		/*
 		 * If this pinned group hasn't been scheduled,
-- 
1.6.1.2