Bluetooth: Fix spec error in the RemoteBusy Logic

On the receipt of an RR(P=1) under RemoteBusy set to TRUE(on the RECV
state table) we have to call sendIorRRorRNR(F=1) and just after set
RemoteBusy to False. This leads to a freeze in the sending process since
it's not allowed send data with RemoteBusy set to true and no one
call SendPending-I-Frames after set RemoteBusy to false(The last action
for that event).

Actually sendIorRRorRNR() calls SendPending-I-Frames but at that moment
RemoteBusy is still True and we cannot send any frame, after, no one
calls SendPending-I-Frames again and the sending process stops.

The solution here is to set RemoteBusy to false inside
SendPending-I-Frames just before call SendPending-I-Frames. That will
make SendPending-I-Frames able to send frames. This solution is similar
to what RR(P=0)(F=0) on the RECV table and RR(P=1) on the SREJ_SENT
table do.

Actually doesn't make any sense call SendPending-I-Frames if we can send
any frame, i. e., RemoteBusy is True.
Signed-off-by: NGustavo F. Padovan <padovan@profusion.mobi>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

net/bluetooth/l2cap.c

@@ -3379,6 +3379,8 @@ static inline void l2cap_send_i_or_rr_or_rnr(struct sock *sk)
 	if (pi->conn_state & L2CAP_CONN_REMOTE_BUSY && pi->unacked_frames > 0)
 		__mod_retrans_timer();
 
+	pi->conn_state &= ~L2CAP_CONN_REMOTE_BUSY;
+
 	spin_lock_bh(&pi->send_lock);
 	l2cap_ertm_send(sk);
 	spin_unlock_bh(&pi->send_lock);
@@ -3936,7 +3938,6 @@ static inline void l2cap_data_channel_rrframe(struct sock *sk, u16 rx_control)
 			l2cap_send_srejtail(sk);
 		} else {
 			l2cap_send_i_or_rr_or_rnr(sk);
-			pi->conn_state &= ~L2CAP_CONN_REMOTE_BUSY;
 		}
 
 	} else if (rx_control & L2CAP_CTRL_FINAL) {