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>

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 819ffc0..0de1997 100644 (file)
--- 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;