[Bluetooth] Store remote modem status for RFCOMM TTY

When switching a RFCOMM socket to a TTY, the remote modem status might
be needed later. Currently it is lost since the original configuration
is done via the socket interface. So store the modem status and reply
it when the socket has been converted to a TTY.
Signed-off-by: NDenis Kenzior <denis.kenzior@trolltech.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

include/net/bluetooth/rfcomm.h

@@ -180,6 +180,7 @@ struct rfcomm_dlc {
 	u8            addr;
 	u8            priority;
 	u8            v24_sig;
+	u8            remote_v24_sig;
 	u8            mscex;
 	u8            out;
 

net/bluetooth/rfcomm/core.c

@@ -1463,8 +1463,12 @@ static int rfcomm_recv_msc(struct rfcomm_session *s, int cr, struct sk_buff *skb
 			clear_bit(RFCOMM_TX_THROTTLED, &d->flags);
 
 		rfcomm_dlc_lock(d);
+
+		d->remote_v24_sig = msc->v24_sig;
+
 		if (d->modem_status)
 			d->modem_status(d, msc->v24_sig);
+
 		rfcomm_dlc_unlock(d);
 
 		rfcomm_send_msc(s, 0, dlci, msc->v24_sig);

net/bluetooth/rfcomm/tty.c

@@ -271,6 +271,9 @@ static int rfcomm_dev_add(struct rfcomm_dev_req *req, struct rfcomm_dlc *dlc)
 
 	dlc->owner = dev;
 	dev->dlc   = dlc;
+
+	rfcomm_dev_modem_status(dlc, dlc->remote_v24_sig);
+
 	rfcomm_dlc_unlock(dlc);
 
 	/* It's safe to call __module_get() here because socket already