netfilter: nft_set_hash: add lookup variant for fixed size hashtable

This patch provides a faster variant of the lookup function for 2 and 4
byte keys. Optimizing the one byte case is not worth, as the set backend
selection will always select the bitmap set type for such case.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nft_set_hash.c b/net/netfilter/nft_set_hash.c
index b2eab94..0fa01d7 100644 (file)
--- a/net/netfilter/nft_set_hash.c
+++ b/net/netfilter/nft_set_hash.c
@@ -409,6 +409,38 @@ static bool nft_hash_lookup(const struct net *net, const struct nft_set *set,
        return false;
 }
 
+/* nft_hash_select_ops() makes sure key size can be either 2 or 4 bytes . */
+static inline u32 nft_hash_key(const u32 *key, u32 klen)
+{
+       if (klen == 4)
+               return *key;
+
+       return *(u16 *)key;
+}
+
+static bool nft_hash_lookup_fast(const struct net *net,
+                                const struct nft_set *set,
+                                const u32 *key, const struct nft_set_ext **ext)
+{
+       struct nft_hash *priv = nft_set_priv(set);
+       u8 genmask = nft_genmask_cur(net);
+       const struct nft_hash_elem *he;
+       u32 hash, k1, k2;
+
+       k1 = nft_hash_key(key, set->klen);
+       hash = jhash_1word(k1, priv->seed);
+       hash = reciprocal_scale(hash, priv->buckets);
+       hlist_for_each_entry_rcu(he, &priv->table[hash], node) {
+               k2 = nft_hash_key(nft_set_ext_key(&he->ext)->data, set->klen);
+               if (k1 == k2 &&
+                   nft_set_elem_active(&he->ext, genmask)) {
+                       *ext = &he->ext;
+                       return true;
+               }
+       }
+       return false;
+}
+
 static int nft_hash_insert(const struct net *net, const struct nft_set *set,
                           const struct nft_set_elem *elem,
                           struct nft_set_ext **ext)
@@ -588,12 +620,36 @@ static struct nft_set_ops nft_hash_ops __read_mostly = {
        .features       = NFT_SET_MAP | NFT_SET_OBJECT,
 };
 
+static struct nft_set_ops nft_hash_fast_ops __read_mostly = {
+       .type           = &nft_hash_type,
+       .privsize       = nft_hash_privsize,
+       .elemsize       = offsetof(struct nft_hash_elem, ext),
+       .estimate       = nft_hash_estimate,
+       .init           = nft_hash_init,
+       .destroy        = nft_hash_destroy,
+       .insert         = nft_hash_insert,
+       .activate       = nft_hash_activate,
+       .deactivate     = nft_hash_deactivate,
+       .flush          = nft_hash_flush,
+       .remove         = nft_hash_remove,
+       .lookup         = nft_hash_lookup_fast,
+       .walk           = nft_hash_walk,
+       .features       = NFT_SET_MAP | NFT_SET_OBJECT,
+};
+
 static const struct nft_set_ops *
 nft_hash_select_ops(const struct nft_ctx *ctx, const struct nft_set_desc *desc,
                    u32 flags)
 {
-       if (desc->size)
-               return &nft_hash_ops;
+       if (desc->size) {
+               switch (desc->klen) {
+               case 2:
+               case 4:
+                       return &nft_hash_fast_ops;
+               default:
+                       return &nft_hash_ops;
+               }
+       }
 
        return &nft_rhash_ops;
 }