[NET]: Add a dev_ioctl() fallback to sock_ioctl()

Currently all network protocols need to call dev_ioctl as the default
fallback in their ioctl implementations.  This patch adds a fallback
to dev_ioctl to sock_ioctl if the protocol returned -ENOIOCTLCMD.
This way all the procotol ioctl handlers can be simplified and we don't
need to export dev_ioctl.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 7c9f192..68afc53 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -434,7 +434,6 @@
 int inet6_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
 {
 	struct sock *sk = sock->sk;
-	int err = -EINVAL;
 
 	switch(cmd) 
 	{
@@ -453,10 +452,9 @@
 	case SIOCSIFDSTADDR:
 		return addrconf_set_dstaddr((void __user *) arg);
 	default:
-		if (!sk->sk_prot->ioctl ||
-		    (err = sk->sk_prot->ioctl(sk, cmd, arg)) == -ENOIOCTLCMD)
-			return(dev_ioctl(cmd,(void __user *) arg));		
-		return err;
+		if (!sk->sk_prot->ioctl)
+			return -ENOIOCTLCMD;
+		return sk->sk_prot->ioctl(sk, cmd, arg);
 	}
 	/*NOTREACHED*/
 	return(0);