From: Kuniyuki Iwashima <kuniyu@google.com>
To: Qingfang Deng <qingfang.deng@linux.dev>
Cc: Eric Dumazet <edumazet@kernel.org>,
Neal Cardwell <ncardwell@google.com>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Simon Horman <horms@kernel.org>,
Yuchung Cheng <ycheng@google.com>, Wei Wang <weiwan@google.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net] tcp: initialize send sequence numbers before deferring TFO
Date: Tue, 3 Nov 2026 05:06:34 +0000 [thread overview]
Message-ID: <aulr0Da_4s4WOp5k@google.com> (raw)
In-Reply-To: <20261102035943.9700-1-qingfang.deng@linux.dev>
On Mon, 02 Nov 2026 11:59:43 +0800, Qingfang Deng wrote:
> TCP_FASTOPEN_CONNECT can return from connect() before tcp_connect_init()
> when a cached cookie or cookieless Fast Open allows deferring the SYN.
> At this point write_seq contains the initial sequence number, while
> snd_una and snd_nxt have not been initialized to that sequence number.
>
> Consequently, inet_diag and /proc/net/tcp{,6} report the initial
> sequence number as the send queue length despite no SYN or payload being
> queued.
>
> Initialize snd_una and snd_nxt to write_seq before marking the
> connection as deferred. Both sequence-based queue lengths then remain
> zero until the first write starts the connection and runs
> tcp_connect_init().
>
> Fixes: 19f6d3f3c842 ("net/tcp-fastopen: Add new API support")
> Signed-off-by: Qingfang Deng <qingfang.deng@linux.dev>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
prev parent reply other threads:[~2026-11-03 5:06 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-02 3:59 Qingfang Deng
2026-11-02 6:11 ` Jiayuan Chen
2026-11-02 7:40 ` Qingfang Deng
2026-11-02 8:00 ` Eric Dumazet
2026-11-02 8:13 ` Qingfang Deng
2026-11-02 8:20 ` Eric Dumazet
2026-11-03 5:31 ` Kuniyuki Iwashima
2026-11-03 14:52 ` Neal Cardwell
2026-11-03 5:06 ` Kuniyuki Iwashima [this message]
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