> -----Original Message----- > From: Eric Dumazet <edumazet@xxxxxxxxxx> > Sent: Thursday, August 21, 2025 2:56 PM > To: Chia-Yu Chang (Nokia) <chia-yu.chang@xxxxxxxxxxxxxxxxxxx> > Cc: pabeni@xxxxxxxxxx; linux-doc@xxxxxxxxxxxxxxx; corbet@xxxxxxx; horms@xxxxxxxxxx; dsahern@xxxxxxxxxx; kuniyu@xxxxxxxxxx; bpf@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; jhs@xxxxxxxxxxxx; kuba@xxxxxxxxxx; stephen@xxxxxxxxxxxxxxxxxx; xiyou.wangcong@xxxxxxxxx; jiri@xxxxxxxxxxx; davem@xxxxxxxxxxxxx; andrew+netdev@xxxxxxx; donald.hunter@xxxxxxxxx; ast@xxxxxxxxxxx; liuhangbin@xxxxxxxxx; shuah@xxxxxxxxxx; linux-kselftest@xxxxxxxxxxxxxxx; ij@xxxxxxxxxx; ncardwell@xxxxxxxxxx; Koen De Schepper (Nokia) <koen.de_schepper@xxxxxxxxxxxxxxxxxxx>; g.white@xxxxxxxxxxxxx; ingemar.s.johansson@xxxxxxxxxxxx; mirja.kuehlewind@xxxxxxxxxxxx; cheshire@xxxxxxxxx; rs.ietf@xxxxxx; Jason_Livingood@xxxxxxxxxxx; vidhi_goel@xxxxxxxxx > Subject: Re: [PATCH v15 net-next 12/14] tcp: accecn: AccECN option failure handling > > > 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 Fri, Aug 15, 2025 at 1:40 AM <chia-yu.chang@xxxxxxxxxxxxxxxxxxx> wrote: > > > > From: Chia-Yu Chang <chia-yu.chang@xxxxxxxxxxxxxxxxxxx> > > > > 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 <ij@xxxxxxxxxx> > > Signed-off-by: Chia-Yu Chang <chia-yu.chang@xxxxxxxxxxxxxxxxxxx> > > Truly invasive changes, what can I say.... > > Not sure why you CC so many folks which will very unlikely give any feedback. > > What is the purpose of WARN_ON_ONCE() in tcp_accecn_option_init() ? > > Just to feed syzbot ? Hi Eric, WARN_ON_ONCE() exists in both tcp_accecn_option_init() and tcp_accecn_process_option(). And the one in tcp_accecn_option_init() is for AccECN option handling during the handshake. Or is it not preferred to put WARN_ON_ONCE() during TCP handshake? Chia-Yu
