[NETFILTER]: non-power-of-two jhash optimizations

[platform/kernel/linux-rpi.git] / net / ipv4 / netfilter / nf_nat_core.c

diff --git a/net/ipv4/netfilter/nf_nat_core.c b/net/ipv4/netfilter/nf_nat_core.c
index aec157d..e53ae1e 100644 (file)
--- a/net/ipv4/netfilter/nf_nat_core.c
+++ b/net/ipv4/netfilter/nf_nat_core.c
@@ -77,10 +77,13 @@ EXPORT_SYMBOL_GPL(nf_nat_proto_put);
 static inline unsigned int
 hash_by_src(const struct nf_conntrack_tuple *tuple)
 {
+       unsigned int hash;
+
        /* Original src, to ensure we map it consistently if poss. */
-       return jhash_3words((__force u32)tuple->src.u3.ip,
+       hash = jhash_3words((__force u32)tuple->src.u3.ip,
                            (__force u32)tuple->src.u.all,
-                           tuple->dst.protonum, 0) % nf_nat_htable_size;
+                           tuple->dst.protonum, 0);
+       return ((u64)hash * nf_nat_htable_size) >> 32;
 }
 
 /* Is this tuple already taken? (not by us) */
@@ -211,7 +214,8 @@ find_best_ips_proto(struct nf_conntrack_tuple *tuple,
        maxip = ntohl(range->max_ip);
        j = jhash_2words((__force u32)tuple->src.u3.ip,
                         (__force u32)tuple->dst.u3.ip, 0);
-       *var_ipp = htonl(minip + j % (maxip - minip + 1));
+       j = ((u64)j * (maxip - minip + 1)) >> 32;
+       *var_ipp = htonl(minip + j);
 }
 
 /* Manipulate the tuple into the range given.  For NF_INET_POST_ROUTING,