tracing/events: fix memory leak when unloading module

When unloading a module, memory allocated by init_preds() and
trace_define_field() is not freed.

[ Impact: fix memory leak ]
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <4A00F6E0.3040503@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/ftrace_event.h

@@ -116,6 +116,7 @@ struct ftrace_event_call {
 #define MAX_FILTER_STR_VAL	128
 
 extern int init_preds(struct ftrace_event_call *call);
+extern void destroy_preds(struct ftrace_event_call *call);
 extern int filter_match_preds(struct ftrace_event_call *call, void *rec);
 extern int filter_current_check_discard(struct ftrace_event_call *call,
 					void *rec,

kernel/trace/trace_events.c

@@ -60,6 +60,22 @@ int trace_define_field(struct ftrace_event_call *call, char *type,
 }
 EXPORT_SYMBOL_GPL(trace_define_field);
 
+#ifdef CONFIG_MODULES
+
+static void trace_destroy_fields(struct ftrace_event_call *call)
+{
+	struct ftrace_event_field *field, *next;
+
+	list_for_each_entry_safe(field, next, &call->fields, link) {
+		list_del(&field->link);
+		kfree(field->type);
+		kfree(field->name);
+		kfree(field);
+	}
+}
+
+#endif /* CONFIG_MODULES */
+
 static void ftrace_clear_events(void)
 {
 	struct ftrace_event_call *call;
@@ -925,6 +941,8 @@ static void trace_module_remove_events(struct module *mod)
 				unregister_ftrace_event(call->event);
 			debugfs_remove_recursive(call->dir);
 			list_del(&call->list);
+			trace_destroy_fields(call);
+			destroy_preds(call);
 		}
 	}
 

kernel/trace/trace_events_filter.c

@@ -346,6 +346,20 @@ static void filter_disable_preds(struct ftrace_event_call *call)
 		filter->preds[i]->fn = filter_pred_none;
 }
 
+void destroy_preds(struct ftrace_event_call *call)
+{
+	struct event_filter *filter = call->filter;
+	int i;
+
+	for (i = 0; i < MAX_FILTER_PRED; i++) {
+		if (filter->preds[i])
+			filter_free_pred(filter->preds[i]);
+	}
+	kfree(filter->preds);
+	kfree(filter);
+	call->filter = NULL;
+}
+
 int init_preds(struct ftrace_event_call *call)
 {
 	struct event_filter *filter;
@@ -374,13 +388,7 @@ int init_preds(struct ftrace_event_call *call)
 	return 0;
 
 oom:
-	for (i = 0; i < MAX_FILTER_PRED; i++) {
-		if (filter->preds[i])
-			filter_free_pred(filter->preds[i]);
-	}
-	kfree(filter->preds);
-	kfree(call->filter);
-	call->filter = NULL;
+	destroy_preds(call);
 
 	return -ENOMEM;
 }