Revert: veth: remove unneeded ifname code from veth_newlink()

84c49d8c3e4abefb0a41a77b25aa37ebe8d6b743 ("veth: remove unneeded
ifname code from veth_newlink()") caused regression on veth
creation. This patch reverts the original one.

Reported-by: Michał Mirosław <mirqus@gmail.com>
Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/veth.c

@@ -403,6 +403,17 @@ static int veth_newlink(struct net *src_net, struct net_device *dev,
 	if (tb[IFLA_ADDRESS] == NULL)
 		random_ether_addr(dev->dev_addr);
 
+	if (tb[IFLA_IFNAME])
+		nla_strlcpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
+	else
+		snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d");
+
+	if (strchr(dev->name, '%')) {
+		err = dev_alloc_name(dev, dev->name);
+		if (err < 0)
+			goto err_alloc_name;
+	}
+
 	err = register_netdevice(dev);
 	if (err < 0)
 		goto err_register_dev;
@@ -422,6 +433,7 @@ static int veth_newlink(struct net *src_net, struct net_device *dev,
 
 err_register_dev:
 	/* nothing to do */
+err_alloc_name:
 err_configure_peer:
 	unregister_netdevice(peer);
 	return err;