lxccontainer: use cgroup_get()

src/lxc/lxccontainer.c

@@ -3296,6 +3296,8 @@ WRAP_API_2(bool, lxcapi_set_cgroup_item, const char *, const char *)
 
 static int do_lxcapi_get_cgroup_item(struct lxc_container *c, const char *subsys, char *retv, int inlen)
 {
+	int ret;
+
 	call_cleaner(cgroup_exit) struct cgroup_ops *cgroup_ops = NULL;
 
 	if (!c)
@@ -3304,12 +3306,16 @@ static int do_lxcapi_get_cgroup_item(struct lxc_container *c, const char *subsys
 	if (is_stopped(c))
 		return -1;
 
-	cgroup_ops = cgroup_init(c->lxc_conf);
-	if (!cgroup_ops)
-		return -1;
+	ret = cgroup_get(c->lxc_conf, subsys, retv, inlen, c->name, c->config_path);
+	if (ret == ENOCGROUP2) {
+		cgroup_ops = cgroup_init(c->lxc_conf);
+		if (!cgroup_ops)
+			return -1;
+
+		return cgroup_ops->get(cgroup_ops, subsys, retv, inlen, c->name, c->config_path);
+	}
 
-	return cgroup_ops->get(cgroup_ops, subsys, retv, inlen, c->name,
-			       c->config_path);
+	return ret;
 }
 
 WRAP_API_3(int, lxcapi_get_cgroup_item, const char *, char *, int)