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>

1 files changed, 15 insertions, 7 deletions

diff --git a/include/net/ndisc.h b/include/net/ndisc.h
index bbc938edf41b..ec48f42db5ed 100644
--- 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;