Revert "net: Guaranetee the proper ordering of the loopback device."

This reverts commit ae33bc40c0d96d02f51a996482ea7e41c5152695.

drivers/net/loopback.c

@@ -204,8 +204,17 @@ static __net_exit void loopback_net_exit(struct net *net)
 	unregister_netdev(dev);
 }
 
-/* Registered in net/core/dev.c */
-struct pernet_operations __net_initdata loopback_net_ops = {
+static struct pernet_operations __net_initdata loopback_net_ops = {
        .init = loopback_net_init,
        .exit = loopback_net_exit,
 };
+
+static int __init loopback_init(void)
+{
+	return register_pernet_device(&loopback_net_ops);
+}
+
+/* Loopback is special. It should be initialized before any other network
+ * device and network subsystem.
+ */
+fs_initcall(loopback_init);

include/linux/netdevice.h

@@ -1766,7 +1766,6 @@ static inline int skb_bond_should_drop(struct sk_buff *skb)
 	return 0;
 }
 
-extern struct pernet_operations __net_initdata loopback_net_ops;
 #endif /* __KERNEL__ */
 
 #endif	/* _LINUX_DEV_H */

net/core/dev.c

@@ -4909,18 +4909,6 @@ static int __init net_dev_init(void)
 	if (register_pernet_subsys(&netdev_net_ops))
 		goto out;
 
-	/* The loopback device is special if any other network devices
-	 * is present in a network namespace the loopback device must
-	 * be present. Since we now dynamically allocate and free the
-	 * loopback device ensure this invariant is maintained by
-	 * keeping the loopback device as the first device on the
-	 * list of network devices.  Ensuring the loopback devices
-	 * is the first device that appears and the last network device
-	 * that disappears.
-	 */
-	if (register_pernet_device(&loopback_net_ops))
-		goto out;
-
 	if (register_pernet_device(&default_device_ops))
 		goto out;