---

yaml
---
r: 364926
b: refs/heads/master
c: 575380d
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 2a30c11f6a037e2475f3c651bc57e697e79fa963
+refs/heads/master: 575380da8b46969a2c6a7e14a51056a63b30fe2e

trunk/include/linux/ftrace_event.h

@@ -197,6 +197,7 @@ enum {
 	TRACE_EVENT_FL_CAP_ANY_BIT,
 	TRACE_EVENT_FL_NO_SET_FILTER_BIT,
 	TRACE_EVENT_FL_IGNORE_ENABLE_BIT,
+	TRACE_EVENT_FL_WAS_ENABLED_BIT,
 };
 
 /*
@@ -205,12 +206,16 @@ enum {
  *  CAP_ANY	  - Any user can enable for perf
  *  NO_SET_FILTER - Set when filter has error and is to be ignored
  *  IGNORE_ENABLE - For ftrace internal events, do not enable with debugfs file
+ *  WAS_ENABLED   - Set and stays set when an event was ever enabled
+ *                    (used for module unloading, if a module event is enabled,
+ *                     it is best to clear the buffers that used it).
  */
 enum {
 	TRACE_EVENT_FL_FILTERED		= (1 << TRACE_EVENT_FL_FILTERED_BIT),
 	TRACE_EVENT_FL_CAP_ANY		= (1 << TRACE_EVENT_FL_CAP_ANY_BIT),
 	TRACE_EVENT_FL_NO_SET_FILTER	= (1 << TRACE_EVENT_FL_NO_SET_FILTER_BIT),
 	TRACE_EVENT_FL_IGNORE_ENABLE	= (1 << TRACE_EVENT_FL_IGNORE_ENABLE_BIT),
+	TRACE_EVENT_FL_WAS_ENABLED	= (1 << TRACE_EVENT_FL_WAS_ENABLED_BIT),
 };
 
 struct ftrace_event_call {

trunk/kernel/trace/trace_events.c

@@ -245,6 +245,9 @@ static int ftrace_event_enable_disable(struct ftrace_event_file *file,
 				break;
 			}
 			file->flags |= FTRACE_EVENT_FL_ENABLED;
+
+			/* WAS_ENABLED gets set but never cleared. */
+			call->flags |= TRACE_EVENT_FL_WAS_ENABLED;
 		}
 		break;
 	}
@@ -1626,12 +1629,13 @@ static void trace_module_remove_events(struct module *mod)
 {
 	struct ftrace_module_file_ops *file_ops;
 	struct ftrace_event_call *call, *p;
-	bool found = false;
+	bool clear_trace = false;
 
 	down_write(&trace_event_mutex);
 	list_for_each_entry_safe(call, p, &ftrace_events, list) {
 		if (call->mod == mod) {
-			found = true;
+			if (call->flags & TRACE_EVENT_FL_WAS_ENABLED)
+				clear_trace = true;
 			__trace_remove_event_call(call);
 		}
 	}
@@ -1648,9 +1652,9 @@ static void trace_module_remove_events(struct module *mod)
 
 	/*
 	 * It is safest to reset the ring buffer if the module being unloaded
-	 * registered any events.
+	 * registered any events that were used.
 	 */
-	if (found)
+	if (clear_trace)
 		tracing_reset_current_online_cpus();
 	up_write(&trace_event_mutex);
 }