cgroup-util: use _cleanup_free_ attribute

src/basic/cgroup-util.c

@@ -2027,7 +2027,7 @@ int cg_kernel_controllers(Set **ret) {
         (void) read_line(f, SIZE_MAX, NULL);
 
         for (;;) {
-                char *controller;
+                _cleanup_free_ char *controller = NULL;
                 int enabled = 0;
 
                 errno = 0;
@@ -2042,17 +2042,13 @@ int cg_kernel_controllers(Set **ret) {
                         return -EBADMSG;
                 }
 
-                if (!enabled) {
-                        free(controller);
+                if (!enabled)
                         continue;
-                }
 
-                if (!cg_controller_is_valid(controller)) {
-                        free(controller);
+                if (!cg_controller_is_valid(controller))
                         return -EBADMSG;
-                }
 
-                r = set_consume(controllers, controller);
+                r = set_consume(controllers, TAKE_PTR(controller));
                 if (r < 0)
                         return r;
         }