batman-adv: only call post function if something changed

Currently, the post function is also called on errors or if there were
no changes, which is redundant for the functions currently using these
facilities.

Signed-off-by: Simon Wunderlich <simon@open-mesh.com>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>

net/batman-adv/sysfs.c

@@ -242,10 +242,13 @@ ssize_t batadv_show_vlan_##_name(struct kobject *kobj,			\
 
 static int batadv_store_bool_attr(char *buff, size_t count,
 				  struct net_device *net_dev,
-				  const char *attr_name, atomic_t *attr)
+				  const char *attr_name, atomic_t *attr,
+				  bool *changed)
 {
 	int enabled = -1;
 
+	*changed = false;
+
 	if (buff[count - 1] == '\n')
 		buff[count - 1] = '\0';
 
@@ -272,6 +275,8 @@ static int batadv_store_bool_attr(char *buff, size_t count,
 		    atomic_read(attr) == 1 ? "enabled" : "disabled",
 		    enabled == 1 ? "enabled" : "disabled");
 
+	*changed = true;
+
 	atomic_set(attr, (unsigned int)enabled);
 	return count;
 }
@@ -282,11 +287,12 @@ __batadv_store_bool_attr(char *buff, size_t count,
 			 struct attribute *attr,
 			 atomic_t *attr_store, struct net_device *net_dev)
 {
+	bool changed;
 	int ret;
 
 	ret = batadv_store_bool_attr(buff, count, net_dev, attr->name,
-				     attr_store);
-	if (post_func && ret)
+				     attr_store, &changed);
+	if (post_func && changed)
 		post_func(net_dev);
 
 	return ret;