14 files changed, 24 insertions, 22 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index b65a5051361f..1421dad4cb29 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3124,8 +3124,7 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
         }
 
         if (map) {
-                tcpu = map->cpus[((u64) hash * map->len) >> 32];
-
+                tcpu = map->cpus[reciprocal_scale(hash, map->len)];
                 if (cpu_online(tcpu)) {
                         cpu = tcpu;
                         goto done;
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 660c6492fb78..8ffcc97871c8 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -298,7 +298,7 @@ u16 __skb_tx_hash(const struct net_device *dev, struct sk_buff *skb,
                 qcount = dev->tc_to_txq[tc].count;
         }
 
-        return (u16) (((u64)skb_get_hash(skb) * qcount) >> 32) + qoffset;
+        return (u16) reciprocal_scale(skb_get_hash(skb), qcount) + qoffset;
 }
 EXPORT_SYMBOL(__skb_tx_hash);
 
@@ -371,9 +371,8 @@ static inline int get_xps_queue(struct net_device *dev, struct sk_buff *skb)
                         if (map->len == 1)
                                 queue_index = map->queues[0];
                         else
-                                queue_index = map->queues[
-                                    ((u64)skb_get_hash(skb) * map->len) >> 32];
-
+                                queue_index = map->queues[reciprocal_scale(skb_get_hash(skb),
+                                                                           map->len)];
                         if (unlikely(queue_index >= dev->real_num_tx_queues))
                                 queue_index = -1;
                 }
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index 43116e8c8e13..9111a4e22155 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -229,7 +229,7 @@ begin:
                         }
                 } else if (score == hiscore && reuseport) {
                         matches++;
-                        if (((u64)phash * matches) >> 32 == 0)
+                        if (reciprocal_scale(phash, matches) == 0)
                                 result = sk;
                         phash = next_pseudo_random32(phash);
                 }
diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c
index 2510c02c2d21..e90f83a3415b 100644
--- a/net/ipv4/netfilter/ipt_CLUSTERIP.c
+++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c
@@ -285,7 +285,7 @@ clusterip_hashfn(const struct sk_buff *skb,
         }
 
         /* node numbers are 1..n, not 0..n */
-        return (((u64)hashval * config->num_total_nodes) >> 32) + 1;
+        return reciprocal_scale(hashval, config->num_total_nodes) + 1;
 }
 
 static inline int
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index f57c0e4c2326..32f9571e776b 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -224,7 +224,7 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum,
                 remaining = (high - low) + 1;
 
                 rand = prandom_u32();
-                first = (((u64)rand * remaining) >> 32) + low;
+                first = reciprocal_scale(rand, remaining) + low;
                 /*
                  * force rand to be an odd multiple of UDP_HTABLE_SIZE
                  */
@@ -448,7 +448,7 @@ begin:
                         }
                 } else if (score == badness && reuseport) {
                         matches++;
-                        if (((u64)hash * matches) >> 32 == 0)
+                        if (reciprocal_scale(hash, matches) == 0)
                                 result = sk;
                         hash = next_pseudo_random32(hash);
                 }
@@ -529,7 +529,7 @@ begin:
                         }
                 } else if (score == badness && reuseport) {
                         matches++;
-                        if (((u64)hash * matches) >> 32 == 0)
+                        if (reciprocal_scale(hash, matches) == 0)
                                 result = sk;
                         hash = next_pseudo_random32(hash);
                 }
diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c
index 262e13c02ec2..826019008958 100644
--- a/net/ipv6/inet6_hashtables.c
+++ b/net/ipv6/inet6_hashtables.c
@@ -198,7 +198,7 @@ begin:
                         }
                 } else if (score == hiscore && reuseport) {
                         matches++;
-                        if (((u64)phash * matches) >> 32 == 0)
+                        if (reciprocal_scale(phash, matches) == 0)
                                 result = sk;
                         phash = next_pseudo_random32(phash);
                 }
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 4836af8f582d..25ffe737b975 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -243,7 +243,7 @@ begin:
                                 goto exact_match;
                 } else if (score == badness && reuseport) {
                         matches++;
-                        if (((u64)hash * matches) >> 32 == 0)
+                        if (reciprocal_scale(hash, matches) == 0)
                                 result = sk;
                         hash = next_pseudo_random32(hash);
                 }
@@ -323,7 +323,7 @@ begin:
                         }
                 } else if (score == badness && reuseport) {
                         matches++;
-                        if (((u64)hash * matches) >> 32 == 0)
+                        if (reciprocal_scale(hash, matches) == 0)
                                 result = sk;
                         hash = next_pseudo_random32(hash);
                 }
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 *
diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c
index 063b726bf1f8..cc56c8bb9bed 100644
--- a/net/sched/sch_fq_codel.c
+++ b/net/sched/sch_fq_codel.c
@@ -77,7 +77,8 @@ static unsigned int fq_codel_hash(const struct fq_codel_sched_data *q,
         hash = jhash_3words((__force u32)keys.dst,
                             (__force u32)keys.src ^ keys.ip_proto,
                             (__force u32)keys.ports, q->perturbation);
-        return ((u64)hash * q->flows_cnt) >> 32;
+
+        return reciprocal_scale(hash, q->flows_cnt);
 }
 
 static unsigned int fq_codel_classify(struct sk_buff *skb, struct Qdisc *sch,