netdev - RE: [PATCH v5 net-next 11/14] tcp: accecn: unset ECT if receive or send ACE=0 in AccECN negotiaion

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Message-ID:
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Date: Thu, 6 Nov 2025 17:30:41 +0000
From: "Chia-Yu Chang (Nokia)" <chia-yu.chang@...ia-bell-labs.com>
To: Paolo Abeni <pabeni@...hat.com>, "edumazet@...gle.com"
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Subject: RE: [PATCH v5 net-next 11/14] tcp: accecn: unset ECT if receive or
 send ACE=0 in AccECN negotiaion

> -----Original Message-----
> From: Paolo Abeni <pabeni@...hat.com> 
> Sent: Thursday, November 6, 2025 1:18 PM
> To: Chia-Yu Chang (Nokia) <chia-yu.chang@...ia-bell-labs.com>; edumazet@...gle.com; parav@...dia.com; linux-doc@...r.kernel.org; corbet@....net; horms@...nel.org; dsahern@...nel.org; kuniyu@...gle.com; bpf@...r.kernel.org; netdev@...r.kernel.org; dave.taht@...il.com; jhs@...atatu.com; kuba@...nel.org; stephen@...workplumber.org; xiyou.wangcong@...il.com; jiri@...nulli.us; davem@...emloft.net; andrew+netdev@...n.ch; donald.hunter@...il.com; ast@...erby.net; liuhangbin@...il.com; shuah@...nel.org; linux-kselftest@...r.kernel.org; ij@...nel.org; ncardwell@...gle.com; Koen De Schepper (Nokia) <koen.de_schepper@...ia-bell-labs.com>; g.white@...lelabs.com; ingemar.s.johansson@...csson.com; mirja.kuehlewind@...csson.com; cheshire <cheshire@...le.com>; rs.ietf@....at; Jason_Livingood@...cast.com; Vidhi Goel <vidhi_goel@...le.com>
> Subject: Re: [PATCH v5 net-next 11/14] tcp: accecn: unset ECT if receive or send ACE=0 in AccECN negotiaion
> 
> 
> CAUTION: This is an external email. Please be very careful when clicking links or opening attachments. See the URL nok.it/ext for additional information.
> 
> 
> 
> On 10/30/25 3:34 PM, chia-yu.chang@...ia-bell-labs.com wrote:
> > @@ -4006,7 +4008,7 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
> >       memset(th, 0, sizeof(struct tcphdr));
> >       th->syn = 1;
> >       th->ack = 1;
> > -     tcp_ecn_make_synack(req, th);
> > +     tcp_ecn_make_synack((struct sock *)sk, req, th);
> >       th->source = htons(ireq->ir_num);
> >       th->dest = ireq->ir_rmt_port;
> >       skb->mark = ireq->ir_mark;
> 
> Whoops, I missed the const cast in the previous revisions. This could make the code generated by the compiler for the caller incorrect - assuming the changed field is actually constant.
> 
> I don't have a good idea on how to address this. Changing the argument type for the whole call chain looks like a no go.
> 
> /P

One thought I have now is to add one extra flag in request_sock.

By using this new flag in rquest_sock after calling tcp_rtx_synack, the ACCECN_FAIL_MODE can be set in sk.

Would it make sense to you?

Chia-Yu