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, 52 insertions, 0 deletions

diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index 9f912e4d4232..14e3f017966b 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -197,6 +197,7 @@ struct neigh_table {
 	__u32			(*hash)(const void *pkey,
 					const struct net_device *dev,
 					__u32 *hash_rnd);
+	bool			(*key_eq)(const struct neighbour *, const void *pkey);
 	int			(*constructor)(struct neighbour *);
 	int			(*pconstructor)(struct pneigh_entry *);
 	void			(*pdestructor)(struct pneigh_entry *);
@@ -247,6 +248,57 @@ static inline void *neighbour_priv(const struct neighbour *n)
 #define NEIGH_UPDATE_F_ISROUTER			0x40000000
 #define NEIGH_UPDATE_F_ADMIN			0x80000000
 
+
+static inline bool neigh_key_eq16(const struct neighbour *n, const void *pkey)
+{
+	return *(const u16 *)n->primary_key == *(const u16 *)pkey;
+}
+
+static inline bool neigh_key_eq32(const struct neighbour *n, const void *pkey)
+{
+	return *(const u32 *)n->primary_key == *(const u32 *)pkey;
+}
+
+static inline bool neigh_key_eq128(const struct neighbour *n, const void *pkey)
+{
+	const u32 *n32 = (const u32 *)n->primary_key;
+	const u32 *p32 = pkey;
+
+	return ((n32[0] ^ p32[0]) | (n32[1] ^ p32[1]) |
+		(n32[2] ^ p32[2]) | (n32[3] ^ p32[3])) == 0;
+}
+
+static inline struct neighbour *___neigh_lookup_noref(
+	struct neigh_table *tbl,
+	bool (*key_eq)(const struct neighbour *n, const void *pkey),
+	__u32 (*hash)(const void *pkey,
+		      const struct net_device *dev,
+		      __u32 *hash_rnd),
+	const void *pkey,
+	struct net_device *dev)
+{
+	struct neigh_hash_table *nht = rcu_dereference_bh(tbl->nht);
+	struct neighbour *n;
+	u32 hash_val;
+
+	hash_val = 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 (n->dev == dev && key_eq(n, pkey))
+			return n;
+	}
+
+	return NULL;
+}
+
+static inline struct neighbour *__neigh_lookup_noref(struct neigh_table *tbl,
+						     const void *pkey,
+						     struct net_device *dev)
+{
+	return ___neigh_lookup_noref(tbl, tbl->key_eq, tbl->hash, pkey, dev);
+}
+
 void neigh_table_init(int index, struct neigh_table *tbl);
 int neigh_table_clear(int index, struct neigh_table *tbl);
 struct neighbour *neigh_lookup(struct neigh_table *tbl, const void *pkey,