From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Mon, 14 May 2012 00:01:46 +0000 (+0200)
Subject: netfilter: xt_HMARK: modulus is expensive for hash calculation
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=c44f5faa8e8c2036da2ba656f79b57a737543aff;p=deliverable%2Flinux.git

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 5817d03105b2..0a96a43108ed 100644
--- 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