neigh: Don't require dst in neigh_hh_init

- Add protocol to neigh_tbl so that dst->ops->protocol is not needed
- Acquire the device from neigh->dev

This results in a neigh_hh_init that will cache the samve values
regardless of the packets flowing through it.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/neighbour.h

@@ -193,6 +193,7 @@ struct neigh_table {
 	int			family;
 	int			entry_size;
 	int			key_len;
+	__be16			protocol;
 	__u32			(*hash)(const void *pkey,
 					const struct net_device *dev,
 					__u32 *hash_rnd);

net/core/neighbour.c

@@ -1263,10 +1263,10 @@ struct neighbour *neigh_event_ns(struct neigh_table *tbl,
 EXPORT_SYMBOL(neigh_event_ns);
 
 /* called with read_lock_bh(&n->lock); */
-static void neigh_hh_init(struct neighbour *n, struct dst_entry *dst)
+static void neigh_hh_init(struct neighbour *n)
 {
-	struct net_device *dev = dst->dev;
-	__be16 prot = dst->ops->protocol;
+	struct net_device *dev = n->dev;
+	__be16 prot = n->tbl->protocol;
 	struct hh_cache	*hh = &n->hh;
 
 	write_lock_bh(&n->lock);
@@ -1296,7 +1296,7 @@ int neigh_resolve_output(struct neighbour *neigh, struct sk_buff *skb)
 		unsigned int seq;
 
 		if (dev->header_ops->cache && !neigh->hh.hh_len)
-			neigh_hh_init(neigh, dst);
+			neigh_hh_init(neigh);
 
 		do {
 			__skb_pull(skb, skb_network_offset(skb));

net/decnet/dn_neigh.c

@@ -97,6 +97,7 @@ struct neigh_table dn_neigh_table = {
 	.family =			PF_DECnet,
 	.entry_size =			NEIGH_ENTRY_SIZE(sizeof(struct dn_neigh)),
 	.key_len =			sizeof(__le16),
+	.protocol =			cpu_to_be16(ETH_P_DNA_RT),
 	.hash =				dn_neigh_hash,
 	.constructor =			dn_neigh_construct,
 	.id =				"dn_neigh_cache",

net/ipv4/arp.c

@@ -152,6 +152,7 @@ static const struct neigh_ops arp_direct_ops = {
 struct neigh_table arp_tbl = {
 	.family		= AF_INET,
 	.key_len	= 4,
+	.protocol	= cpu_to_be16(ETH_P_IP),
 	.hash		= arp_hash,
 	.constructor	= arp_constructor,
 	.proxy_redo	= parp_redo,

net/ipv6/ndisc.c

@@ -117,6 +117,7 @@ static const struct neigh_ops ndisc_direct_ops = {
 struct neigh_table nd_tbl = {
 	.family =	AF_INET6,
 	.key_len =	sizeof(struct in6_addr),
+	.protocol =	cpu_to_be16(ETH_P_IPV6),
 	.hash =		ndisc_hash,
 	.constructor =	ndisc_constructor,
 	.pconstructor =	pndisc_constructor,