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>

5 files changed, 46 insertions, 7 deletions

diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c
index b1a5f9777b7e..d6ec3720c77e 100644
--- a/net/bridge/br_netfilter.c
+++ b/net/bridge/br_netfilter.c
@@ -109,11 +109,17 @@ static u32 *fake_cow_metrics(struct dst_entry *dst, unsigned long old)
         return NULL;
 }
 
+static struct neighbour *fake_neigh_lookup(const struct dst_entry *dst, const void *daddr)
+{
+        return NULL;
+}
+
 static struct dst_ops fake_dst_ops = {
         .family =               AF_INET,
         .protocol =             cpu_to_be16(ETH_P_IP),
         .update_pmtu =          fake_update_pmtu,
         .cow_metrics =          fake_cow_metrics,
+        .neigh_lookup =         fake_neigh_lookup,
 };
 
 /*
diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c
index 9bd45fcb3b8e..43450c100226 100644
--- a/net/decnet/dn_route.c
+++ b/net/decnet/dn_route.c
@@ -116,6 +116,7 @@ static void dn_dst_destroy(struct dst_entry *);
 static struct dst_entry *dn_dst_negative_advice(struct dst_entry *);
 static void dn_dst_link_failure(struct sk_buff *);
 static void dn_dst_update_pmtu(struct dst_entry *dst, u32 mtu);
+static struct neighbour *dn_dst_neigh_lookup(const struct dst_entry *dst, const void *daddr);
 static int dn_route_input(struct sk_buff *);
 static void dn_run_flush(unsigned long dummy);
 
@@ -139,6 +140,7 @@ static struct dst_ops dn_dst_ops = {
         .negative_advice =      dn_dst_negative_advice,
         .link_failure =         dn_dst_link_failure,
         .update_pmtu =          dn_dst_update_pmtu,
+        .neigh_lookup =         dn_dst_neigh_lookup,
 };
 
 static void dn_dst_destroy(struct dst_entry *dst)
@@ -827,6 +829,11 @@ static unsigned int dn_dst_default_mtu(const struct dst_entry *dst)
         return dst->dev->mtu;
 }
 
+static struct neighbour *dn_dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
+{
+        return __neigh_lookup_errno(&dn_neigh_table, daddr, dst->dev);
+}
+
 static int dn_rt_set_next_hop(struct dn_route *rt, struct dn_fib_res *res)
 {
         struct dn_fib_info *fi = res->fi;
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)
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 2998cb5be90b..ddef80f568b0 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -127,6 +127,11 @@ static u32 *ipv6_cow_metrics(struct dst_entry *dst, unsigned long old)
         return p;
 }
 
+static struct neighbour *ip6_neigh_lookup(const struct dst_entry *dst, const void *daddr)
+{
+        return __neigh_lookup_errno(&nd_tbl, daddr, dst->dev);
+}
+
 static struct dst_ops ip6_dst_ops_template = {
         .family                 =       AF_INET6,
         .protocol               =       cpu_to_be16(ETH_P_IPV6),
@@ -142,6 +147,7 @@ static struct dst_ops ip6_dst_ops_template = {
         .link_failure           =       ip6_link_failure,
         .update_pmtu            =       ip6_rt_update_pmtu,
         .local_out              =       __ip6_local_out,
+        .neigh_lookup           =       ip6_neigh_lookup,
 };
 
 static unsigned int ip6_blackhole_default_mtu(const struct dst_entry *dst)
@@ -168,6 +174,7 @@ static struct dst_ops ip6_dst_blackhole_ops = {
         .default_advmss         =       ip6_default_advmss,
         .update_pmtu            =       ip6_rt_blackhole_update_pmtu,
         .cow_metrics            =       ip6_rt_blackhole_cow_metrics,
+        .neigh_lookup           =       ip6_neigh_lookup,
 };
 
 static const u32 ip6_template_metrics[RTAX_MAX] = {
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 7803eb6af414..94fdcc7f1030 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -2385,6 +2385,11 @@ static unsigned int xfrm_default_mtu(const struct dst_entry *dst)
         return dst_mtu(dst->path);
 }
 
+static struct neighbour *xfrm_neigh_lookup(const struct dst_entry *dst, const void *daddr)
+{
+        return dst_neigh_lookup(dst->path, daddr);
+}
+
 int xfrm_policy_register_afinfo(struct xfrm_policy_afinfo *afinfo)
 {
         struct net *net;
@@ -2410,6 +2415,8 @@ int xfrm_policy_register_afinfo(struct xfrm_policy_afinfo *afinfo)
                         dst_ops->negative_advice = xfrm_negative_advice;
                 if (likely(dst_ops->link_failure == NULL))
                         dst_ops->link_failure = xfrm_link_failure;
+                if (likely(dst_ops->neigh_lookup == NULL))
+                        dst_ops->neigh_lookup = xfrm_neigh_lookup;
                 if (likely(afinfo->garbage_collect == NULL))
                         afinfo->garbage_collect = __xfrm_garbage_collect;
                 xfrm_policy_afinfo[afinfo->family] = afinfo;