[PATCH v2 07/15] USB: mct_u232: fix TIOCMIWAIT and disconnect

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Make sure to wake up any process sleeping on the modem-status-change
queue at port remove.

Currently a process waiting on modem status changes will not
necessarily be woken on device disconnect.

Note that we need to use the disconnected flag to detect disconnect as
the port private data may have been freed when woken up.

Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Johan Hovold <jhovold@xxxxxxxxx>
---
 drivers/usb/serial/mct_u232.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/serial/mct_u232.c b/drivers/usb/serial/mct_u232.c
index a64d420..ebf9b89 100644
--- a/drivers/usb/serial/mct_u232.c
+++ b/drivers/usb/serial/mct_u232.c
@@ -421,6 +421,7 @@ static int mct_u232_port_remove(struct usb_serial_port *port)
 	struct mct_u232_private *priv;
 
 	priv = usb_get_serial_port_data(port);
+	wake_up_interruptible(&priv->msr_wait);
 	kfree(priv);
 
 	return 0;
@@ -817,12 +818,14 @@ static int  mct_u232_ioctl(struct tty_struct *tty,
 			/* see if a signal did it */
 			if (signal_pending(current))
 				return -ERESTARTSYS;
+
+			if (port->serial->disconnected)
+				return -EIO;
+
 			spin_lock_irqsave(&mct_u232_port->lock, flags);
 			cnow = mct_u232_port->icount;
 			spin_unlock_irqrestore(&mct_u232_port->lock, flags);
-			if (cnow.rng == cprev.rng && cnow.dsr == cprev.dsr &&
-			    cnow.dcd == cprev.dcd && cnow.cts == cprev.cts)
-				return -EIO; /* no change => error */
+
 			if (((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
 			    ((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
 			    ((arg & TIOCM_CD)  && (cnow.dcd != cprev.dcd)) ||
-- 
1.8.1.1

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