diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 7736fe8..777c6c3 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -825,6 +825,7 @@
 	return match;							\
 }
 
+extern struct mutex event_mutex;
 extern struct list_head ftrace_events;
 
 extern const char *__start___trace_bprintk_fmt[];