This is a note to let you know that I've just added the patch titled
tcp: minor optimization in tcp_add_backlog()
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tcp-minor-optimization-in-tcp_add_backlog.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 12702edd66647697122f9e659ab2e5193e09164c
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Mon Nov 15 11:02:30 2021 -0800
tcp: minor optimization in tcp_add_backlog()
[ Upstream commit d519f350967a60b85a574ad8aeac43f2b4384746 ]
If packet is going to be coalesced, sk_sndbuf/sk_rcvbuf values
are not used. Defer their access to the point we need them.
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Stable-dep-of: ec00ed472bdb ("tcp: avoid premature drops in tcp_add_backlog()")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 0dd917c5a7da6..1567072071633 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1678,8 +1678,7 @@ int tcp_v4_early_demux(struct sk_buff *skb)
bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb)
{
- u32 limit = READ_ONCE(sk->sk_rcvbuf) + READ_ONCE(sk->sk_sndbuf);
- u32 tail_gso_size, tail_gso_segs;
+ u32 limit, tail_gso_size, tail_gso_segs;
struct skb_shared_info *shinfo;
const struct tcphdr *th;
struct tcphdr *thtail;
@@ -1786,7 +1785,7 @@ bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb)
* to reduce memory overhead, so add a little headroom here.
* Few sockets backlog are possibly concurrently non empty.
*/
- limit += 64*1024;
+ limit = READ_ONCE(sk->sk_rcvbuf) + READ_ONCE(sk->sk_sndbuf) + 64*1024;
if (unlikely(sk_add_backlog(sk, skb, limit))) {
bh_unlock_sock(sk);
