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net: tcp: allow zero-window ACK update the window

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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>
This commit is contained in:
Menglong Dong 2023-08-11 10:55:28 +08:00 committed by David S. Miller
parent e2142825c1
commit 800a666141
1 changed files with 1 additions and 1 deletions
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2
net/ipv4/tcp_input.c
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@ -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 */