netfilter: xt_HMARK: modulus is expensive for hash calculation

Use:

((u64)(HASH_VAL * HASH_SIZE)) >> 32

as suggested by David S. Miller.

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

diff --git a/net/netfilter/xt_HMARK.c b/net/netfilter/xt_HMARK.c
index 5817d03105b23a35de565c4d31433d6b5232f40a..0a96a43108edde1dcdc251a168f0547c9f277378 100644 (file)
--- a/net/netfilter/xt_HMARK.c
+++ b/net/netfilter/xt_HMARK.c
@@ -109,7 +109,7 @@ hmark_hash(struct hmark_tuple *t, const struct xt_hmark_info *info)
        hash = jhash_3words(t->src, t->dst, t->uports.v32, info->hashrnd);
        hash = hash ^ (t->proto & info->proto_mask);
 
-       return (hash % info->hmodulus) + info->hoffset;
+       return (((u64)hash * info->hmodulus) >> 32) + info->hoffset;
 }
 
 static void