[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>

net/ipv4/devinet.c

@@ -1056,10 +1056,9 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
 	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);
 			}

net/ipv6/addrconf.c

@@ -2256,14 +2256,14 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event,
 	struct net_device *dev = (struct net_device *) data;
 	struct inet6_dev *idev = __in6_dev_get(dev);
 	int run_pending = 0;
+	int err;
 
 	switch(event) {
 	case NETDEV_REGISTER:
 		if (!idev && dev->mtu >= IPV6_MIN_MTU) {
 			idev = ipv6_add_dev(dev);
 			if (!idev)
-				printk(KERN_WARNING "IPv6: add_dev failed for %s\n",
-					dev->name);
+				return notifier_from_errno(-ENOMEM);
 		}
 		break;
 	case NETDEV_UP:
@@ -2373,7 +2373,9 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event,
 					      NULL);
 			addrconf_sysctl_register(idev, &idev->cnf);
 #endif
-			snmp6_register_dev(idev);
+			err = snmp6_register_dev(idev);
+			if (err)
+				return notifier_from_errno(err);
 		}
 		break;
 	}