tracing: Remove test of NULL define_fields callback

Every event (or event class) has it's define_fields callback,
so the test is redundant.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4BFA37BC.8080707@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace_events.c

@@ -987,23 +987,21 @@ event_create_dir(struct ftrace_event_call *call, struct dentry *d_events,
 		 		  id);
 #endif
 
-	if (call->class->define_fields) {
+	/*
-		/*
+	 * Other events may have the same class. Only update
-		 * Other events may have the same class. Only update
+	 * the fields if they are not already defined.
-		 * the fields if they are not already defined.
+	 */
-		 */
+	head = trace_get_fields(call);
-		head = trace_get_fields(call);
+	if (list_empty(head)) {
-		if (list_empty(head)) {
+		ret = call->class->define_fields(call);
-			ret = call->class->define_fields(call);
+		if (ret < 0) {
-			if (ret < 0) {
+			pr_warning("Could not initialize trace point"
-				pr_warning("Could not initialize trace point"
+				   " events/%s\n", call->name);
-					   " events/%s\n", call->name);
+			return ret;
-				return ret;
-			}
 		}
-		trace_create_file("filter", 0644, call->dir, call,
-				  filter);
 	}
+	trace_create_file("filter", 0644, call->dir, call,
+			  filter);
 
 	trace_create_file("format", 0444, call->dir, call,
 			  format);

kernel/trace/trace_events_filter.c

@@ -639,9 +639,6 @@ static int init_subsystem_preds(struct event_subsystem *system)
 	int err;
 
 	list_for_each_entry(call, &ftrace_events, list) {
-		if (!call->class || !call->class->define_fields)
-			continue;
-
 		if (strcmp(call->class->system, system->name) != 0)
 			continue;
 
@@ -658,9 +655,6 @@ static void filter_free_subsystem_preds(struct event_subsystem *system)
 	struct ftrace_event_call *call;
 
 	list_for_each_entry(call, &ftrace_events, list) {
-		if (!call->class || !call->class->define_fields)
-			continue;
-
 		if (strcmp(call->class->system, system->name) != 0)
 			continue;
 
@@ -1263,9 +1257,6 @@ static int replace_system_preds(struct event_subsystem *system,
 	list_for_each_entry(call, &ftrace_events, list) {
 		struct event_filter *filter = call->filter;
 
-		if (!call->class || !call->class->define_fields)
-			continue;
-
 		if (strcmp(call->class->system, system->name) != 0)
 			continue;