ndisc: Introduce __ipv6_neigh_lookup_noref().

This function, which looks up neighbour entry for an IPv6 address
without touching refcnt, will be used for patches to remove
dependency on rt->n (neighbour entry in rt6_info).

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/ndisc.h b/include/net/ndisc.h
index bbc938e..ec48f42 100644 (file)
--- a/include/net/ndisc.h
+++ b/include/net/ndisc.h
@@ -148,14 +148,13 @@ static inline u32 ndisc_hashfn(const void *pkey, const struct net_device *dev, _
                (p32[3] * hash_rnd[3]));
 }
 
-static inline struct neighbour *__ipv6_neigh_lookup(struct net_device *dev, const void *pkey)
+static inline struct neighbour *__ipv6_neigh_lookup_noref(struct net_device *dev, const void *pkey)
 {
        struct neigh_hash_table *nht;
        const u32 *p32 = pkey;
        struct neighbour *n;
        u32 hash_val;
 
-       rcu_read_lock_bh();
        nht = rcu_dereference_bh(nd_tbl.nht);
        hash_val = ndisc_hashfn(pkey, dev, nht->hash_rnd) >> (32 - nht->hash_shift);
        for (n = rcu_dereference_bh(nht->hash_buckets[hash_val]);
@@ -164,12 +163,21 @@ static inline struct neighbour *__ipv6_neigh_lookup(struct net_device *dev, cons
                u32 *n32 = (u32 *) n->primary_key;
                if (n->dev == dev &&
                    ((n32[0] ^ p32[0]) | (n32[1] ^ p32[1]) |
-                    (n32[2] ^ p32[2]) | (n32[3] ^ p32[3])) == 0) {
-                       if (!atomic_inc_not_zero(&n->refcnt))
-                               n = NULL;
-                       break;
-               }
+                    (n32[2] ^ p32[2]) | (n32[3] ^ p32[3])) == 0)
+                       return n;
        }
+
+       return NULL;
+}
+
+static inline struct neighbour *__ipv6_neigh_lookup(struct net_device *dev, const void *pkey)
+{
+       struct neighbour *n;
+
+       rcu_read_lock_bh();
+       n = __ipv6_neigh_lookup_noref(dev, pkey);
+       if (n && !atomic_inc_not_zero(&n->refcnt))
+               n = NULL;
        rcu_read_unlock_bh();
 
        return n;