diff --git a/net/atm/lec.c b/net/atm/lec.c
index e4853b50cf40..4b98f897044a 100644
--- a/net/atm/lec.c
+++ b/net/atm/lec.c
@@ -410,9 +410,11 @@ static int lec_atm_send(struct atm_vcc *vcc, struct sk_buff *skb)
 		priv->lane2_ops = NULL;
 		if (priv->lane_version > 1)
 			priv->lane2_ops = &lane2_ops;
+		rtnl_lock();
 		if (dev_set_mtu(dev, mesg->content.config.mtu))
 			pr_info("%s: change_mtu to %d failed\n",
 				dev->name, mesg->content.config.mtu);
+		rtnl_unlock();
 		priv->is_proxy = mesg->content.config.is_proxy;
 		break;
 	case l_flush_tran_id: