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>

4 files changed, 26 insertions, 16 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();
diff --git a/net/decnet/dn_neigh.c b/net/decnet/dn_neigh.c
index f123c6c6748c..ee7d1cef0027 100644
--- a/net/decnet/dn_neigh.c
+++ b/net/decnet/dn_neigh.c
@@ -93,12 +93,18 @@ static u32 dn_neigh_hash(const void *pkey,
         return jhash_2words(*(__u16 *)pkey, 0, hash_rnd[0]);
 }
 
+static bool dn_key_eq(const struct neighbour *neigh, const void *pkey)
+{
+        return neigh_key_eq16(neigh, pkey);
+}
+
 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,
+        .key_eq =                       dn_key_eq,
         .constructor =                  dn_neigh_construct,
         .id =                           "dn_neigh_cache",
         .parms ={
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 6b8aad6a0d7d..5f5c674e130a 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -122,6 +122,7 @@
  *      Interface to generic neighbour cache.
  */
 static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd);
+static bool arp_key_eq(const struct neighbour *n, const void *pkey);
 static int arp_constructor(struct neighbour *neigh);
 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
 static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
@@ -154,6 +155,7 @@ struct neigh_table arp_tbl = {
         .key_len        = 4,
         .protocol       = cpu_to_be16(ETH_P_IP),
         .hash           = arp_hash,
+        .key_eq         = arp_key_eq,
         .constructor    = arp_constructor,
         .proxy_redo     = parp_redo,
         .id             = "arp_cache",
@@ -209,7 +211,12 @@ static u32 arp_hash(const void *pkey,
                     const struct net_device *dev,
                     __u32 *hash_rnd)
 {
-        return arp_hashfn(*(u32 *)pkey, dev, *hash_rnd);
+        return arp_hashfn(pkey, dev, hash_rnd);
+}
+
+static bool arp_key_eq(const struct neighbour *neigh, const void *pkey)
+{
+        return neigh_key_eq32(neigh, pkey);
 }
 
 static int arp_constructor(struct neighbour *neigh)
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index e363bbc2420d..247ad7c298f7 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -84,6 +84,7 @@ do {								\
 static u32 ndisc_hash(const void *pkey,
                       const struct net_device *dev,
                       __u32 *hash_rnd);
+static bool ndisc_key_eq(const struct neighbour *neigh, const void *pkey);
 static int ndisc_constructor(struct neighbour *neigh);
 static void ndisc_solicit(struct neighbour *neigh, struct sk_buff *skb);
 static void ndisc_error_report(struct neighbour *neigh, struct sk_buff *skb);
@@ -119,6 +120,7 @@ struct neigh_table nd_tbl = {
         .key_len =      sizeof(struct in6_addr),
         .protocol =     cpu_to_be16(ETH_P_IPV6),
         .hash =         ndisc_hash,
+        .key_eq =       ndisc_key_eq,
         .constructor =  ndisc_constructor,
         .pconstructor = pndisc_constructor,
         .pdestructor =  pndisc_destructor,
@@ -295,6 +297,11 @@ static u32 ndisc_hash(const void *pkey,
         return ndisc_hashfn(pkey, dev, hash_rnd);
 }
 
+static bool ndisc_key_eq(const struct neighbour *n, const void *pkey)
+{
+        return neigh_key_eq128(n, pkey);
+}
+
 static int ndisc_constructor(struct neighbour *neigh)
 {
         struct in6_addr *addr = (struct in6_addr *)&neigh->primary_key;