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authorChia-Yu Chang <chia-yu.chang@nokia-bell-labs.com>2026-01-31 23:25:04 +0100
committerPaolo Abeni <pabeni@redhat.com>2026-02-03 15:13:24 +0100
commit100f946b8d44b64bc0b8a8c30d283105031c0a77 (patch)
treec3c21e2c43b6dc3c64ee018456df136de46057e2 /net/ipv4
parent6f74bc8b6e8d0e8218c1342682dadb156603d13e (diff)
tcp: ECT_1_NEGOTIATION and NEEDS_ACCECN identifiers
Two flags for congestion control (CC) module are added in this patch related to AccECN negotiation. First, a new flag (TCP_CONG_NEEDS_ACCECN) defines that the CC expects to negotiate AccECN functionality using the ECE, CWR and AE flags in the TCP header. Second, during ECN negotiation, ECT(0) in the IP header is used. This patch enables CC to control whether ECT(0) or ECT(1) should be used on a per-segment basis. A new flag (TCP_CONG_ECT_1_NEGOTIATION) defines the expected ECT value in the IP header by the CA when not-yet initialized for the connection. The detailed AccECN negotiaotn can be found in IETF RFC9768. Co-developed-by: Olivier Tilmans <olivier.tilmans@nokia.com> Signed-off-by: Olivier Tilmans <olivier.tilmans@nokia.com> Signed-off-by: Ilpo Järvinen <ij@kernel.org> Signed-off-by: Chia-Yu Chang <chia-yu.chang@nokia-bell-labs.com> Acked-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20260131222515.8485-5-chia-yu.chang@nokia-bell-labs.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/tcp_cong.c5
-rw-r--r--net/ipv4/tcp_input.c3
2 files changed, 5 insertions, 3 deletions
diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index df758adbb445..e9f6c77e0631 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -16,6 +16,7 @@
#include <linux/gfp.h>
#include <linux/jhash.h>
#include <net/tcp.h>
+#include <net/tcp_ecn.h>
#include <trace/events/tcp.h>
static DEFINE_SPINLOCK(tcp_cong_list_lock);
@@ -227,7 +228,7 @@ void tcp_assign_congestion_control(struct sock *sk)
memset(icsk->icsk_ca_priv, 0, sizeof(icsk->icsk_ca_priv));
if (ca->flags & TCP_CONG_NEEDS_ECN)
- INET_ECN_xmit(sk);
+ INET_ECN_xmit_ect_1_negotiation(sk);
else
INET_ECN_dontxmit(sk);
}
@@ -257,7 +258,7 @@ static void tcp_reinit_congestion_control(struct sock *sk,
memset(icsk->icsk_ca_priv, 0, sizeof(icsk->icsk_ca_priv));
if (ca->flags & TCP_CONG_NEEDS_ECN)
- INET_ECN_xmit(sk);
+ INET_ECN_xmit_ect_1_negotiation(sk);
else
INET_ECN_dontxmit(sk);
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 38852e04229a..e823a3b1ad3b 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -7495,7 +7495,8 @@ static void tcp_ecn_create_request(struct request_sock *req,
u32 ecn_ok_dst;
if (tcp_accecn_syn_requested(th) &&
- READ_ONCE(net->ipv4.sysctl_tcp_ecn) >= 3) {
+ (READ_ONCE(net->ipv4.sysctl_tcp_ecn) >= 3 ||
+ tcp_ca_needs_accecn(listen_sk))) {
inet_rsk(req)->ecn_ok = 1;
tcp_rsk(req)->accecn_ok = 1;
tcp_rsk(req)->syn_ect_rcv = TCP_SKB_CB(skb)->ip_dsfield &