diff mbox series

[net-next,v4,2/4] net: tcp: allow zero-window ACK update the window

Message ID 20230811025530.3510703-3-imagedong@tencent.com (mailing list archive)
State Accepted
Commit 800a666141de75baebb59b347b9c9e43d963e4da
Delegated to: Netdev Maintainers
Headers show
Series net: tcp: support probing OOM | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1333 this patch: 1333
netdev/cc_maintainers success CCed 6 of 6 maintainers
netdev/build_clang success Errors and warnings before: 1353 this patch: 1353
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1356 this patch: 1356
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 8 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Menglong Dong Aug. 11, 2023, 2:55 a.m. UTC 
From: Menglong Dong <imagedong@tencent.com>

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>
---
 net/ipv4/tcp_input.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Eric Dumazet Aug. 11, 2023, 7:37 a.m. UTC | #1 
On Fri, Aug 11, 2023 at 5:01 AM <menglong8.dong@gmail.com> wrote:
>
> From: Menglong Dong <imagedong@tencent.com>
>
> 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>
diff mbox series

Patch

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 2ac059483410..d34d52fdfdb1 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 */