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>

1 files changed, 19 insertions, 7 deletions

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 1d4cd3b4fd69..33137307d52a 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -185,6 +185,8 @@ static u32 *ipv4_cow_metrics(struct dst_entry *dst, unsigned long old)
 	return p;
 }
 
+static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst, const void *daddr);
+
 static struct dst_ops ipv4_dst_ops = {
 	.family =		AF_INET,
 	.protocol =		cpu_to_be16(ETH_P_IP),
@@ -199,6 +201,7 @@ static struct dst_ops ipv4_dst_ops = {
 	.link_failure =		ipv4_link_failure,
 	.update_pmtu =		ip_rt_update_pmtu,
 	.local_out =		__ip_local_out,
+	.neigh_lookup =		ipv4_neigh_lookup,
 };
 
 #define ECN_OR_COST(class)	TC_PRIO_##class
@@ -1008,22 +1011,30 @@ static int slow_chain_length(const struct rtable *head)
 	return length >> FRACT_BITS;
 }
 
-static int rt_bind_neighbour(struct rtable *rt)
+static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst, const void *daddr)
 {
-	static const __be32 inaddr_any = 0;
-	struct net_device *dev = rt->dst.dev;
 	struct neigh_table *tbl = &arp_tbl;
-	const __be32 *nexthop;
+	static const __be32 inaddr_any = 0;
+	struct net_device *dev = dst->dev;
+	const __be32 *pkey = daddr;
 	struct neighbour *n;
 
 #if defined(CONFIG_ATM_CLIP) || defined(CONFIG_ATM_CLIP_MODULE)
 	if (dev->type == ARPHRD_ATM)
 		tbl = clip_tbl_hook;
 #endif
-	nexthop = &rt->rt_gateway;
 	if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT))
-		nexthop = &inaddr_any;
-	n = ipv4_neigh_lookup(tbl, dev, nexthop);
+		pkey = &inaddr_any;
+
+	n = __ipv4_neigh_lookup(tbl, dev, *(__force u32 *)pkey);
+	if (n)
+		return n;
+	return neigh_create(tbl, pkey, dev);
+}
+
+static int rt_bind_neighbour(struct rtable *rt)
+{
+	struct neighbour *n = ipv4_neigh_lookup(&rt->dst, &rt->rt_gateway);
 	if (IS_ERR(n))
 		return PTR_ERR(n);
 	dst_set_neighbour(&rt->dst, n);
@@ -2734,6 +2745,7 @@ static struct dst_ops ipv4_dst_blackhole_ops = {
 	.default_advmss		=	ipv4_default_advmss,
 	.update_pmtu		=	ipv4_rt_blackhole_update_pmtu,
 	.cow_metrics		=	ipv4_rt_blackhole_cow_metrics,
+	.neigh_lookup		=	ipv4_neigh_lookup,
 };
 
 struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_orig)