neigh: Factor out ___neigh_lookup_noref

While looking at the mpls code I found myself writing yet another
version of neigh_lookup_noref.  We currently have __ipv4_lookup_noref
and __ipv6_lookup_noref.

So to make my work a little easier and to make it a smidge easier to
verify/maintain the mpls code in the future I stopped and wrote
___neigh_lookup_noref.  Then I rewote __ipv4_lookup_noref and
__ipv6_lookup_noref in terms of this new function.  I tested my new
version by verifying that the same code is generated in
ip_finish_output2 and ip6_finish_output2 where these functions are
inlined.

To get to ___neigh_lookup_noref I added a new neighbour cache table
function key_eq.  So that the static size of the key would be
available.

I also added __neigh_lookup_noref for people who want to to lookup
a neighbour table entry quickly but don't know which neibhgour table
they are going to look up.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 15 deletions

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 0f48ea3affed..fe3c6eac5805 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -397,25 +397,15 @@ struct neighbour *neigh_lookup(struct neigh_table *tbl, const void *pkey,
                                struct net_device *dev)
 {
         struct neighbour *n;
-        int key_len = tbl->key_len;
-        u32 hash_val;
-        struct neigh_hash_table *nht;
 
         NEIGH_CACHE_STAT_INC(tbl, lookups);
 
         rcu_read_lock_bh();
-        nht = rcu_dereference_bh(tbl->nht);
-        hash_val = tbl->hash(pkey, dev, nht->hash_rnd) >> (32 - nht->hash_shift);
-
-        for (n = rcu_dereference_bh(nht->hash_buckets[hash_val]);
-             n != NULL;
-             n = rcu_dereference_bh(n->next)) {
-                if (dev == n->dev && !memcmp(n->primary_key, pkey, key_len)) {
-                        if (!atomic_inc_not_zero(&n->refcnt))
-                                n = NULL;
-                        NEIGH_CACHE_STAT_INC(tbl, hits);
-                        break;
-                }
+        n = __neigh_lookup_noref(tbl, pkey, dev);
+        if (n) {
+                if (!atomic_inc_not_zero(&n->refcnt))
+                        n = NULL;
+                NEIGH_CACHE_STAT_INC(tbl, hits);
         }
 
         rcu_read_unlock_bh();