mptcp: keep snd_una updated for fallback socket

After shutdown, for fallback MPTCP sockets, we always have

write_seq == snd_una+1

The above will foul OUTQ ioctl(). Keep snd_una in sync with
write_seq even after shutdown.

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 df5a0cf..f6fc0f0 100644 (file)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2666,6 +2666,7 @@ static void __mptcp_check_send_data_fin(struct sock *sk)
         * state now
         */
        if (__mptcp_check_fallback(msk)) {
+               WRITE_ONCE(msk->snd_una, msk->write_seq);
                if ((1 << sk->sk_state) & (TCPF_CLOSING | TCPF_LAST_ACK)) {
                        inet_sk_state_store(sk, TCP_CLOSE);
                        mptcp_close_wake_up(sk);