-----Original Message----- From: Paolo Abeni pabeni@redhat.com Sent: Thursday, November 6, 2025 12:39 PM To: Chia-Yu Chang (Nokia) chia-yu.chang@nokia-bell-labs.com; edumazet@google.com; parav@nvidia.com; linux-doc@vger.kernel.org; corbet@lwn.net; horms@kernel.org; dsahern@kernel.org; kuniyu@google.com; bpf@vger.kernel.org; netdev@vger.kernel.org; dave.taht@gmail.com; jhs@mojatatu.com; kuba@kernel.org; stephen@networkplumber.org; xiyou.wangcong@gmail.com; jiri@resnulli.us; davem@davemloft.net; andrew+netdev@lunn.ch; donald.hunter@gmail.com; ast@fiberby.net; liuhangbin@gmail.com; shuah@kernel.org; linux-kselftest@vger.kernel.org; ij@kernel.org; ncardwell@google.com; Koen De Schepper (Nokia) koen.de_schepper@nokia-bell-labs.com; g.white@cablelabs.com; ingemar.s.johansson@ericsson.com; mirja.kuehlewind@ericsson.com; cheshire cheshire@apple.com; rs.ietf@gmx.at; Jason_Livingood@comcast.com; Vidhi Goel vidhi_goel@apple.com Cc: Olivier Tilmans (Nokia) olivier.tilmans@nokia.com Subject: Re: [PATCH v5 net-next 05/14] tcp: L4S ECT(1) identifier and NEEDS_ACCECN for CC modules
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On 10/30/25 3:34 PM, chia-yu.chang@nokia-bell-labs.com wrote:
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 7f5df7a71f62..d475f80b2248 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -328,12 +328,17 @@ static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb, struct tcphdr *th, int tcp_header_len) { struct tcp_sock *tp = tcp_sk(sk);
bool ecn_ect_1; if (!tcp_ecn_mode_any(tp)) return;ecn_ect_1 = tp->ecn_flags & TCP_ECN_ECT_1;if (ecn_ect_1 && !tcp_accecn_ace_fail_recv(tp))__INET_ECN_xmit(sk, true);I'm possibly lost, but I can't find ecn_flags TCP_ECN_ECT_1 bit being set here or elsewhere in this series.
Also why isn't this chunk under `if (tcp_ecn_mode_accecn(tp))` ?
/P
Hi Paolo,
This bit will be set by congestion control (TCP Prague, which will be submitted after AccECN patch series).
It is intended to use ECT-1 rather than ECT-0, and we were thinking this flag can be irrespective to AccECN negotiation.
Shall I put in the Prague patch series?
Chia-Yu