From b40671b5ee588c8a61b2d0eacbad32ffc57e9a8f Mon Sep 17 00:00:00 2001 From: Chia-Yu Chang Date: Tue, 16 Sep 2025 10:24:32 +0200 Subject: tcp: accecn: AccECN option failure handling MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit AccECN option may fail in various way, handle these: - Attempt to negotiate the use of AccECN on the 1st retransmitted SYN - From the 2nd retransmitted SYN, stop AccECN negotiation - Remove option from SYN/ACK rexmits to handle blackholes - If no option arrives in SYN/ACK, assume Option is not usable - If an option arrives later, re-enabled - If option is zeroed, disable AccECN option processing This patch use existing padding bits in tcp_request_sock and holes in tcp_sock without increasing the size. Signed-off-by: Ilpo Järvinen Signed-off-by: Chia-Yu Chang Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20250916082434.100722-9-chia-yu.chang@nokia-bell-labs.com Signed-off-by: Paolo Abeni --- include/linux/tcp.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/tcp.h b/include/linux/tcp.h index f637b659b35a..3ca5ed02de6d 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -173,6 +173,7 @@ struct tcp_request_sock { u8 syn_ect_snt: 2, syn_ect_rcv: 2, accecn_fail_mode:4; + u8 saw_accecn_opt :2; #ifdef CONFIG_TCP_AO u8 ao_keyid; u8 ao_rcv_next; @@ -407,7 +408,8 @@ struct tcp_sock { syn_fastopen_child:1; /* created TFO passive child socket */ u8 keepalive_probes; /* num of allowed keep alive probes */ - u8 accecn_fail_mode:4; /* AccECN failure handling */ + u8 accecn_fail_mode:4, /* AccECN failure handling */ + saw_accecn_opt:2; /* An AccECN option was seen */ u32 tcp_tx_delay; /* delay (in usec) added to TX packets */ /* RTT measurement */ -- cgit v1.2.3