6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Paolo Abeni <pabeni@xxxxxxxxxx> [ Upstream commit c0f5aec28edf98906d28f08daace6522adf9ee7a ] 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@xxxxxxxxxx> Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx> Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- 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 70b7a47a53c7..d3c5ecf8ddf5 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -783,7 +783,8 @@ 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