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-rw-r--r--include/linux/ftrace_event.h9
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;
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