From 800a666141de75baebb59b347b9c9e43d963e4da Mon Sep 17 00:00:00 2001
From: Menglong Dong <imagedong@tencent.com>
Date: Fri, 11 Aug 2023 10:55:28 +0800
Subject: [PATCH] net: tcp: allow zero-window ACK update the window
Fow now, an ACK can update the window in following case, according to
the tcp_may_update_window():
1. the ACK acknowledged new data
2. the ACK has new data
3. the ACK expand the window and the seq of it is valid
Now, we allow the ACK update the window if the window is 0, and the
seq/ack of it is valid. This is for the case that the receiver replies
an zero-window ACK when it is under memory stress and can't queue the new
data.
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/ipv4/tcp_input.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 2ac0594834101..d34d52fdfdb1e 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3525,7 +3525,7 @@ static inline bool tcp_may_update_window(const struct tcp_sock *tp,
{
return after(ack, tp->snd_una) ||
after(ack_seq, tp->snd_wl1) ||
- (ack_seq == tp->snd_wl1 && nwin > tp->snd_wnd);
+ (ack_seq == tp->snd_wl1 && (nwin > tp->snd_wnd || !nwin));
}
/* If we update tp->snd_una, also update tp->bytes_acked */
--
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