cgroup: Skip mkdir() and subtree control if group already exists

- No point in doing it twice
 - Don't anger the gods (possible kernel bugs)

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/cgroup.c

@@ -86,16 +86,18 @@ static void group_init(char *path, int leaf, const char *cfg)
 {
 	char *ptr, *s;
 
-	if (mkdir(path, 0755) && EEXIST != errno) {
+	if (!fisdir(path)) {
-		_pe("Failed creating cgroup %s", path);
+		if (mkdir(path, 0755)) {
-		return;
+			_pe("Failed creating cgroup %s", path);
+			return;
+		}
+
+		/* enable detected controllers on domain groups */
+		if (!leaf && fnwrite(controllers, "%s/cgroup.subtree_control", path))
+			_pe("Failed enabling %s for %s", controllers, path);
 	}
 
-	/* enable detected controllers on domain groups */
+	if (!cfg || !cfg[0])
-	if (!leaf && fnwrite(controllers, "%s/cgroup.subtree_control", path))
-		_pe("Failed enabling %s for %s", controllers, path);
-
-	if (!cfg)
 		return;
 
 	s = strdupa(cfg);