1 files changed, 8 insertions, 1 deletions

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 5ac97a42950d..dc7fc646fa2e 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -169,7 +169,14 @@ struct ftrace_event_call {
          *   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;