From d21dbdfe0afb5195607d207f894fe86d5b322d46 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Fri, 18 Nov 2016 17:18:03 -0800
Subject: [PATCH] udp: avoid one cache line miss in recvmsg()
UDP_SKB_CB(skb)->partial_cov is located at offset 66 in skb,
requesting a cold cache line being read in cpu cache.
We can avoid this cache line miss for UDP sockets,
as partial_cov has a meaning only for UDPLite.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/ipv4/udp.c | 3 ++-
net/ipv6/udp.c | 3 ++-
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index e1fc0116e8d59..b949770fdc083 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1389,7 +1389,8 @@ int udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
* coverage checksum (UDP-Lite), do it before the copy.
*/
- if (copied < ulen || UDP_SKB_CB(skb)->partial_cov || peeking) {
+ if (copied < ulen || peeking ||
+ (is_udplite && UDP_SKB_CB(skb)->partial_cov)) {
checksum_valid = !udp_lib_checksum_complete(skb);
if (!checksum_valid)
goto csum_copy_err;
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 4f99417d9b401..8fd4d89380b86 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -363,7 +363,8 @@ int udpv6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
* coverage checksum (UDP-Lite), do it before the copy.
*/
- if (copied < ulen || UDP_SKB_CB(skb)->partial_cov || peeking) {
+ if (copied < ulen || peeking ||
+ (is_udplite && UDP_SKB_CB(skb)->partial_cov)) {
checksum_valid = !udp_lib_checksum_complete(skb);
if (!checksum_valid)
goto csum_copy_err;
--
GitLab