net: Add ->neigh_lookup() operation to dst_ops

In the future dst entries will be neigh-less.  In that environment we
need to have an easy transition point for current users of
dst->neighbour outside of the packet output fast path.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/arp.h b/include/net/arp.h
index 5e669e6f..4979af8b 100644
--- a/include/net/arp.h
+++ b/include/net/arp.h
@@ -38,15 +38,6 @@
 	return n;
 }
 
-static inline struct neighbour *ipv4_neigh_lookup(struct neigh_table *tbl, struct net_device *dev, const __be32 *pkey)
-{
-	struct neighbour *n = __ipv4_neigh_lookup(tbl, dev,
-						  *(__force u32 *)pkey);
-	if (n)
-		return n;
-	return neigh_create(tbl, pkey, dev);
-}
-
 extern void	arp_init(void);
 extern int	arp_find(unsigned char *haddr, struct sk_buff *skb);
 extern int	arp_ioctl(struct net *net, unsigned int cmd, void __user *arg);
diff --git a/include/net/dst.h b/include/net/dst.h
index 8147206..29e2557 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -387,6 +387,11 @@
 	}
 }
 
+static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
+{
+	return dst->ops->neigh_lookup(dst, daddr);
+}
+
 static inline void dst_link_failure(struct sk_buff *skb)
 {
 	struct dst_entry *dst = skb_dst(skb);
diff --git a/include/net/dst_ops.h b/include/net/dst_ops.h
index dc07463..9adb998 100644
--- a/include/net/dst_ops.h
+++ b/include/net/dst_ops.h
@@ -26,6 +26,7 @@
 	void			(*link_failure)(struct sk_buff *);
 	void			(*update_pmtu)(struct dst_entry *dst, u32 mtu);
 	int			(*local_out)(struct sk_buff *skb);
+	struct neighbour *	(*neigh_lookup)(const struct dst_entry *dst, const void *daddr);
 
 	struct kmem_cache	*kmem_cachep;