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>
diff --git a/net/batman-adv/sysfs.c b/net/batman-adv/sysfs.c
index 48e2aad..fe87777 100644
--- a/net/batman-adv/sysfs.c
+++ b/net/batman-adv/sysfs.c
@@ -242,10 +242,13 @@
 
 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 @@
 		    atomic_read(attr) == 1 ? "enabled" : "disabled",
 		    enabled == 1 ? "enabled" : "disabled");
 
+	*changed = true;
+
 	atomic_set(attr, (unsigned int)enabled);
 	return count;
 }
@@ -282,11 +287,12 @@
 			 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;