[IPV4/IPV6]: Fail registration if inet device construction fails

Now that netdev notifications can fail, we can use this to signal
errors during registration for IPv4/IPv6.  In particular, if we
fail to allocate memory for the inet device, we can fail the netdev
registration.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index abf6352..5b77bda 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1056,10 +1056,9 @@
 	if (!in_dev) {
 		if (event == NETDEV_REGISTER) {
 			in_dev = inetdev_init(dev);
+			if (!in_dev)
+				return notifier_from_errno(-ENOMEM);
 			if (dev == &loopback_dev) {
-				if (!in_dev)
-					panic("devinet: "
-					      "Failed to create loopback\n");
 				IN_DEV_CONF_SET(in_dev, NOXFRM, 1);
 				IN_DEV_CONF_SET(in_dev, NOPOLICY, 1);
 			}