[bug report] mptcp: refine mptcp_cleanup_rbuf

[Dan Carpenter <dan.carpenter@oracle.com>]

Hello Paolo Abeni,

The patch fde56eea01f9: "mptcp: refine mptcp_cleanup_rbuf" from Jun
22, 2021, leads to the following static checker warning:

	net/mptcp/protocol.c:464 mptcp_subflow_could_cleanup()
	warn: masking a bool

net/mptcp/protocol.c
   455  static bool mptcp_subflow_could_cleanup(const struct sock *ssk, bool rx_empty)
   456  {
   457          const struct inet_connection_sock *icsk = inet_csk(ssk);
   458          bool ack_pending = READ_ONCE(icsk->icsk_ack.pending);
                ^^^^^^^^^^^^^^^^

   459          const struct tcp_sock *tp = tcp_sk(ssk);
   460  
   461          return (ack_pending & ICSK_ACK_SCHED) &&
                                      ^^^^^^^^^^^^^^
This is 1 so it works

   462                  ((READ_ONCE(tp->rcv_nxt) - READ_ONCE(tp->rcv_wup) >
   463                    READ_ONCE(icsk->icsk_ack.rcv_mss)) ||
   464                   (rx_empty && ack_pending &
   465                                (ICSK_ACK_PUSHED2 | ICSK_ACK_PUSHED)));
                                       ^^^^^^^^^^^^^^^^
This is 8 so it doesn't work

   466  }

regards,
dan carpenter