diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 5ac97a4..dc7fc64 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -169,7 +169,14 @@
 	 *   bit 1:		enabled
 	 *   bit 2:		filter_active
 	 *
-	 *  Must hold event_mutex to change.
+	 * Changes to flags must hold the event_mutex.
+	 *
+	 * Note: Reads of flags do not hold the event_mutex since
+	 * they occur in critical sections. But the way flags
+	 * is currently used, these changes do no affect the code
+	 * except that when a change is made, it may have a slight
+	 * delay in propagating the changes to other CPUs due to
+	 * caching and such.
 	 */
 	unsigned int		flags;