perf_events, trace: Fix perf_trace_destroy(), mutex went missing

Steve spotted I forgot to do the destroy under event_mutex.

Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1274451913.1674.1707.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 4 insertions, 1 deletions

diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 49c7abf2ba5c..e6f65887842c 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -132,8 +132,9 @@ void perf_trace_destroy(struct perf_event *p_event)
         struct ftrace_event_call *tp_event = p_event->tp_event;
         int i;
 
+        mutex_lock(&event_mutex);
         if (--tp_event->perf_refcount > 0)
-                return;
+                goto out;
 
         if (tp_event->class->reg)
                 tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER);
@@ -157,6 +158,8 @@ void perf_trace_destroy(struct perf_event *p_event)
                         perf_trace_buf[i] = NULL;
                 }
         }
+out:
+        mutex_unlock(&event_mutex);
 }
 
 __kprobes void *perf_trace_buf_prepare(int size, unsigned short type,