net: use reciprocal_scale() helper

Replace open codings of (((u64) <x> * <y>) >> 32) with reciprocal_scale().

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

6 files changed, 10 insertions, 7 deletions

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 0b634e7f1652..5016a6929085 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -142,7 +142,7 @@ static u32 hash_conntrack_raw(const struct nf_conntrack_tuple *tuple, u16 zone)
 
 static u32 __hash_bucket(u32 hash, unsigned int size)
 {
-	return ((u64)hash * size) >> 32;
+	return reciprocal_scale(hash, size);
 }
 
 static u32 hash_bucket(u32 hash, const struct net *net)
diff --git a/net/netfilter/nf_conntrack_expect.c b/net/netfilter/nf_conntrack_expect.c
index f87e8f68ad45..91a1837acd0e 100644
--- a/net/netfilter/nf_conntrack_expect.c
+++ b/net/netfilter/nf_conntrack_expect.c
@@ -83,7 +83,8 @@ static unsigned int nf_ct_expect_dst_hash(const struct nf_conntrack_tuple *tuple
 	hash = jhash2(tuple->dst.u3.all, ARRAY_SIZE(tuple->dst.u3.all),
 		      (((tuple->dst.protonum ^ tuple->src.l3num) << 16) |
 		       (__force __u16)tuple->dst.u.all) ^ nf_conntrack_hash_rnd);
-	return ((u64)hash * nf_ct_expect_hsize) >> 32;
+
+	return reciprocal_scale(hash, nf_ct_expect_hsize);
 }
 
 struct nf_conntrack_expect *
diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c
index 552f97cd9fde..4e0b47831d43 100644
--- a/net/netfilter/nf_nat_core.c
+++ b/net/netfilter/nf_nat_core.c
@@ -126,7 +126,8 @@ hash_by_src(const struct net *net, u16 zone,
 	/* Original src, to ensure we map it consistently if poss. */
 	hash = jhash2((u32 *)&tuple->src, sizeof(tuple->src) / sizeof(u32),
 		      tuple->dst.protonum ^ zone ^ nf_conntrack_hash_rnd);
-	return ((u64)hash * net->ct.nat_htable_size) >> 32;
+
+	return reciprocal_scale(hash, net->ct.nat_htable_size);
 }
 
 /* Is this tuple already taken? (not by us) */
@@ -274,7 +275,7 @@ find_best_ips_proto(u16 zone, struct nf_conntrack_tuple *tuple,
 		}
 
 		var_ipp->all[i] = (__force __u32)
-			htonl(minip + (((u64)j * dist) >> 32));
+			htonl(minip + reciprocal_scale(j, dist));
 		if (var_ipp->all[i] != range->max_addr.all[i])
 			full_range = true;
 
diff --git a/net/netfilter/xt_HMARK.c b/net/netfilter/xt_HMARK.c
index 73b73f687c58..02afaf48a729 100644
--- a/net/netfilter/xt_HMARK.c
+++ b/net/netfilter/xt_HMARK.c
@@ -126,7 +126,7 @@ hmark_hash(struct hmark_tuple *t, const struct xt_hmark_info *info)
 	hash = jhash_3words(src, dst, t->uports.v32, info->hashrnd);
 	hash = hash ^ (t->proto & info->proto_mask);
 
-	return (((u64)hash * info->hmodulus) >> 32) + info->hoffset;
+	return reciprocal_scale(hash, info->hmodulus) + info->hoffset;
 }
 
 static void
diff --git a/net/netfilter/xt_cluster.c b/net/netfilter/xt_cluster.c
index f4af1bfafb1c..96fa26b20b67 100644
--- a/net/netfilter/xt_cluster.c
+++ b/net/netfilter/xt_cluster.c
@@ -55,7 +55,8 @@ xt_cluster_hash(const struct nf_conn *ct,
 		WARN_ON(1);
 		break;
 	}
-	return (((u64)hash * info->total_nodes) >> 32);
+
+	return reciprocal_scale(hash, info->total_nodes);
 }
 
 static inline bool
diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c
index 47dc6836830a..52eb3e03458d 100644
--- a/net/netfilter/xt_hashlimit.c
+++ b/net/netfilter/xt_hashlimit.c
@@ -135,7 +135,7 @@ hash_dst(const struct xt_hashlimit_htable *ht, const struct dsthash_dst *dst)
 	 * give results between [0 and cfg.size-1] and same hash distribution,
 	 * but using a multiply, less expensive than a divide
 	 */
-	return ((u64)hash * ht->cfg.size) >> 32;
+	return reciprocal_scale(hash, ht->cfg.size);
 }
 
 static struct dsthash_ent *