[PATCH 4.4 028/101] USB: serial: quatech2: fix sleep-while-atomic in close

[Greg Kroah-Hartman]

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

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

From: Johan Hovold <johan@xxxxxxxxxx>

commit f09d1886a41e9063b43da493ef0e845ac8afd2fa upstream.

The write URB was being killed using the synchronous interface while
holding a spin lock in close().

Simply drop the lock and busy-flag update, something which would have
been taken care of by the completion handler if the URB was in flight.

Fixes: f7a33e608d9a ("USB: serial: add quatech2 usb to serial driver")
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/usb/serial/quatech2.c |    4 ----
 1 file changed, 4 deletions(-)

--- a/drivers/usb/serial/quatech2.c
+++ b/drivers/usb/serial/quatech2.c
@@ -408,16 +408,12 @@ static void qt2_close(struct usb_serial_
 {
 	struct usb_serial *serial;
 	struct qt2_port_private *port_priv;
-	unsigned long flags;
 	int i;
 
 	serial = port->serial;
 	port_priv = usb_get_serial_port_data(port);
 
-	spin_lock_irqsave(&port_priv->urb_lock, flags);
 	usb_kill_urb(port_priv->write_urb);
-	port_priv->urb_in_use = false;
-	spin_unlock_irqrestore(&port_priv->urb_lock, flags);
 
 	/* flush the port transmit buffer */
 	i = usb_control_msg(serial->dev,