udp: use atomic_inc_not_zero_hint

UDP sockets refcount is usually 2, unless an incoming frame is going to
be queued in receive or backlog queue.

Using atomic_inc_not_zero_hint() permits to reduce latency, because
processor issues less memory transactions.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 5e0a3a582a5..491ecd3f7a0 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -430,7 +430,7 @@ begin:
 
         if (result) {
 exact_match:
-                if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt)))
+                if (unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2)))
                         result = NULL;
                 else if (unlikely(compute_score2(result, net, saddr, sport,
                                   daddr, hnum, dif) < badness)) {
@@ -500,7 +500,7 @@ begin:
                 goto begin;
 
         if (result) {
-                if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt)))
+                if (unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2)))
                         result = NULL;
                 else if (unlikely(compute_score(result, net, saddr, hnum, sport,
                                   daddr, dport, dif) < badness)) {