While testing the blamed commit below, I was able to miss (!) packetdrill failures in the fastopen test-cases. On passive fastopen the child socket is created by incoming TCP MPC syn, allow for both MPC_SYN and MPC_ACK header. Fixes: 724b00c12957 ("mptcp: refine opt_mp_capable determination") Reviewed-by: Matthieu Baerts <matttbe@kernel.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com> --- net/mptcp/subflow.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index XXXXXXX..XXXXXXX 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -XXX,XX +XXX,XX @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk, * options. */ mptcp_get_options(skb, &mp_opt); - if (!(mp_opt.suboptions & OPTION_MPTCP_MPC_ACK)) + if (!(mp_opt.suboptions & + (OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_ACK))) fallback = true; } else if (subflow_req->mp_join) { -- 2.43.0 While testing the blamed commit below, I was able to miss (!) packetdrill failures in the fastopen test-cases. On passive fastopen the child socket is created by incoming TCP MPC syn, allow for both MPC_SYN and MPC_ACK header. Fixes: 724b00c12957 ("mptcp: refine opt_mp_capable determination") Signed-off-by: Paolo Abeni <pabeni@redhat.com> --- v1 -> v2: - keep it simple don't bother handling DSS OoO pkts (matttbe) --- net/mptcp/subflow.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index XXXXXXX..XXXXXXX 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -XXX,XX +XXX,XX @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk, * options. */ mptcp_get_options(skb, &mp_opt); - if (!(mp_opt.suboptions & OPTION_MPTCP_MPC_ACK)) + if (!(mp_opt.suboptions & + (OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_ACK))) fallback = true; } else if (subflow_req->mp_join) { -- 2.43.0