netdev - Re: [PATCH v9 net-next 10/15] tcp: accecn: unset ECT if receive or send ACE=0 in AccECN negotiaion

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Message-ID: <CANn89iK5jhfO7B1yZK11bEs4DyF3Wjfr6DUgOt-JMDzEAs+94A@mail.gmail.com>
Date: Tue, 20 Jan 2026 19:21:57 +0100
From: Eric Dumazet <edumazet@...gle.com>
To: "Chia-Yu Chang (Nokia)" <chia-yu.chang@...ia-bell-labs.com>
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Subject: Re: [PATCH v9 net-next 10/15] tcp: accecn: unset ECT if receive or
 send ACE=0 in AccECN negotiaion

On Tue, Jan 20, 2026 at 7:11 PM Chia-Yu Chang (Nokia)
<chia-yu.chang@...ia-bell-labs.com> wrote:
>
>
> Hi Eric,
>
> Thanks for the feedback.
> Do you mean sk_listener here is read-only despite there is no const here?

It is not const because we probably need to increment reference counts on it.

But if you have 1000 SYN_RECV, they might share the same listener
socket, and we do not lock the listener socket,
this would not scale very well on servers with 10,000,000 tcp sockets :)

So using any listener-fields to store 'per-syn-recv' information is racy.

>
> Then, could you help to suggest the way please?
> Beacuse for AccECN, here we need to set fail flag after retransmitting SYN/ACK > 1 time.

Why not use state in req itself ? (Or tcp_rsk())

> And this was done within tcp_make_synack(), but now move to every place where could retransmit SYN/ACK.
>
> Thanks.
> Chia-Yu