From 63342411efd2d9350ad405205da036cd45ed1640 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Mon, 5 May 2014 11:49:16 +0200
Subject: [PATCH] perf: Validate locking assumption

Document and validate the locking assumption of event_sched_in().

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-sybq1publ9xt5no77cwvi0eo@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/events/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 819ffc006d67..0de199729f04 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1678,6 +1678,8 @@ event_sched_in(struct perf_event *event,
 	u64 tstamp = perf_event_time(event);
 	int ret = 0;
 
+	lockdep_assert_held(&ctx->lock);
+
 	if (event->state <= PERF_EVENT_STATE_OFF)
 		return 0;