mptcp: poll allow write call before actual connect

If fastopen is used, poll must allow a first write that will trigger
the SYN+data

Similar to what is done in tcp_poll().

Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Benjamin Hesmans <benjamin.hesmans@tessares.net>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index fc753896caa022db73433d85828cd36b5a1062f0..16c3a6fc347fd4acb67a10c468e5ae73af98c966 100644 (file)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3548,6 +3548,7 @@ static int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 
 do_connect:
        err = ssock->ops->connect(ssock, uaddr, addr_len, flags);
+       inet_sk(sock->sk)->defer_connect = inet_sk(ssock->sk)->defer_connect;
        sock->state = ssock->state;
 
        /* on successful connect, the msk state will be moved to established by
@@ -3698,6 +3699,9 @@ static __poll_t mptcp_poll(struct file *file, struct socket *sock,
        if (state != TCP_SYN_SENT && state != TCP_SYN_RECV) {
                mask |= mptcp_check_readable(msk);
                mask |= mptcp_check_writeable(msk);
+       } else if (state == TCP_SYN_SENT && inet_sk(sk)->defer_connect) {
+               /* cf tcp_poll() note about TFO */
+               mask |= EPOLLOUT | EPOLLWRNORM;
        }
        if (sk->sk_shutdown == SHUTDOWN_MASK || state == TCP_CLOSE)
                mask |= EPOLLHUP;