mptcp: fix poll after shutdown

The current mptcp_poll() implementation gives unexpected
results after shutdown(SEND_SHUTDOWN) and when the msk
status is TCP_CLOSE.

Set the correct mask.

Fixes: 8edf08649eed ("mptcp: rework poll+nospace handling")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 9eecd13..42ca499 100644 (file)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3321,7 +3321,7 @@ static __poll_t mptcp_check_writeable(struct mptcp_sock *msk)
        struct sock *sk = (struct sock *)msk;
 
        if (unlikely(sk->sk_shutdown & SEND_SHUTDOWN))
-               return 0;
+               return EPOLLOUT | EPOLLWRNORM;
 
        if (sk_stream_is_writeable(sk))
                return EPOLLOUT | EPOLLWRNORM;
@@ -3354,6 +3354,8 @@ static __poll_t mptcp_poll(struct file *file, struct socket *sock,
                mask |= mptcp_check_readable(msk);
                mask |= mptcp_check_writeable(msk);
        }
+       if (sk->sk_shutdown == SHUTDOWN_MASK || state == TCP_CLOSE)
+               mask |= EPOLLHUP;
        if (sk->sk_shutdown & RCV_SHUTDOWN)
                mask |= EPOLLIN | EPOLLRDNORM | EPOLLRDHUP;