From f1eaea5585e4d193e007d671f0916f4371c72c0b Mon Sep 17 00:00:00 2001 From: Chia-Yu Chang Date: Sat, 31 Jan 2026 23:25:08 +0100 Subject: [PATCH] tcp: add TCP_SYNACK_RETRANS synack_type Before this patch, retransmitted SYN/ACK did not have a specific synack_type; however, the upcoming patch needs to distinguish between retransmitted and non-retransmitted SYN/ACK for AccECN negotiation to transmit the fallback SYN/ACK during AccECN negotiation. Therefore, this patch introduces a new synack_type (TCP_SYNACK_RETRANS). Signed-off-by: Chia-Yu Chang Acked-by: Paolo Abeni Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260131222515.8485-9-chia-yu.chang@nokia-bell-labs.com Signed-off-by: Paolo Abeni --- include/net/tcp.h | 1 + net/ipv4/tcp_output.c | 3 ++- 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index cace4fbe38d0..6c12be2cdd4d 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -552,6 +552,7 @@ enum tcp_synack_type { TCP_SYNACK_NORMAL, TCP_SYNACK_FASTOPEN, TCP_SYNACK_COOKIE, + TCP_SYNACK_RETRANS, }; struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, struct request_sock *req, diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index b28596655d73..a1596fe8dd9f 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -3929,6 +3929,7 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, switch (synack_type) { case TCP_SYNACK_NORMAL: + case TCP_SYNACK_RETRANS: skb_set_owner_edemux(skb, req_to_sk(req)); break; case TCP_SYNACK_COOKIE: @@ -4614,7 +4615,7 @@ int tcp_rtx_synack(const struct sock *sk, struct request_sock *req) /* Paired with WRITE_ONCE() in sock_setsockopt() */ if (READ_ONCE(sk->sk_txrehash) == SOCK_TXREHASH_ENABLED) WRITE_ONCE(tcp_rsk(req)->txhash, net_tx_rndhash()); - res = af_ops->send_synack(sk, NULL, &fl, req, NULL, TCP_SYNACK_NORMAL, + res = af_ops->send_synack(sk, NULL, &fl, req, NULL, TCP_SYNACK_RETRANS, NULL); if (!res) { TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); -- 2.47.3