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>

2 files changed, 4 insertions, 6 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;
                 }