[PATCH 242/270] USB: quatech2: fix io after disconnect

[Herton Ronaldo Krzesinski]

3.5.7u1 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <jhovold at gmail.com>

commit 2f0295adf6438188c4cd0868f2b1976a2b034e1d upstream.

Make sure no control urb is submitted during close after a disconnect by
checking the disconnected flag.

Signed-off-by: Johan Hovold <jhovold at gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 drivers/usb/serial/quatech2.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/usb/serial/quatech2.c b/drivers/usb/serial/quatech2.c
index d170271..09d736a 100644
--- a/drivers/usb/serial/quatech2.c
+++ b/drivers/usb/serial/quatech2.c
@@ -434,6 +434,12 @@ static void qt2_close(struct usb_serial_port *port)
 	port_priv->urb_in_use = false;
 	spin_unlock_irqrestore(&port_priv->urb_lock, flags);
 
+	mutex_lock(&port->serial->disc_mutex);
+	if (port->serial->disconnected) {
+		mutex_unlock(&port->serial->disc_mutex);
+		return;
+	}
+
 	/* flush the port transmit buffer */
 	i = usb_control_msg(serial->dev,
 			    usb_rcvctrlpipe(serial->dev, 0),
@@ -465,6 +471,7 @@ static void qt2_close(struct usb_serial_port *port)
 		dev_err(&port->dev, "%s - close port failed %i\n",
 			__func__, i);
 
+	mutex_unlock(&port->serial->disc_mutex);
 }
 
 static void qt2_disconnect(struct usb_serial *serial)
-- 
1.7.9.5