tracing/events: use list_for_entry_continue

Simplify s_next() and t_next().
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4AB32389.1030005@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace_events.c

@@ -271,42 +271,32 @@ ftrace_event_write(struct file *file, const char __user *ubuf,
 static void *
 t_next(struct seq_file *m, void *v, loff_t *pos)
 {
-	struct list_head *list = m->private;
-	struct ftrace_event_call *call;
+	struct ftrace_event_call *call = v;
 
 	(*pos)++;
 
-	for (;;) {
-		if (list == &ftrace_events)
-			return NULL;
-
-		call = list_entry(list, struct ftrace_event_call, list);
-
+	list_for_each_entry_continue(call, &ftrace_events, list) {
 		/*
 		 * The ftrace subsystem is for showing formats only.
 		 * They can not be enabled or disabled via the event files.
 		 */
 		if (call->regfunc)
-			break;
-
-		list = list->next;
+			return call;
 	}
 
-	m->private = list->next;
-
-	return call;
+	return NULL;
 }
 
 static void *t_start(struct seq_file *m, loff_t *pos)
 {
-	struct ftrace_event_call *call = NULL;
+	struct ftrace_event_call *call;
 	loff_t l;
 
 	mutex_lock(&event_mutex);
 
-	m->private = ftrace_events.next;
+	call = list_entry(&ftrace_events, struct ftrace_event_call, list);
 	for (l = 0; l <= *pos; ) {
-		call = t_next(m, NULL, &l);
+		call = t_next(m, call, &l);
 		if (!call)
 			break;
 	}
@@ -316,37 +306,28 @@ static void *t_start(struct seq_file *m, loff_t *pos)
 static void *
 s_next(struct seq_file *m, void *v, loff_t *pos)
 {
-	struct list_head *list = m->private;
-	struct ftrace_event_call *call;
+	struct ftrace_event_call *call = v;
 
 	(*pos)++;
 
- retry:
-	if (list == &ftrace_events)
-		return NULL;
-
-	call = list_entry(list, struct ftrace_event_call, list);
-
-	if (!call->enabled) {
-		list = list->next;
-		goto retry;
+	list_for_each_entry_continue(call, &ftrace_events, list) {
+		if (call->enabled)
+			return call;
 	}
 
-	m->private = list->next;
-
-	return call;
+	return NULL;
 }
 
 static void *s_start(struct seq_file *m, loff_t *pos)
 {
-	struct ftrace_event_call *call = NULL;
+	struct ftrace_event_call *call;
 	loff_t l;
 
 	mutex_lock(&event_mutex);
 
-	m->private = ftrace_events.next;
+	call = list_entry(&ftrace_events, struct ftrace_event_call, list);
 	for (l = 0; l <= *pos; ) {
-		call = s_next(m, NULL, &l);
+		call = s_next(m, call, &l);
 		if (!call)
 			break;
 	}