From: Eric Dumazet <edumazet@google.com>
Date: Sat, 19 Nov 2016 01:18:03 +0000 (-0800)
Subject: udp: avoid one cache line miss in recvmsg()
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=d21dbdfe0afb5195607d207f894fe86d5b322d46;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

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>
---

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index e1fc0116e8d5..b949770fdc08 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1389,7 +1389,8 @@ try_again:
 	 * 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 4f99417d9b40..8fd4d89380b8 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -363,7 +363,8 @@ try_again:
 	 * 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;