USB: serial: opticon: stop all I/O on close()

Make sure to stop any submitted write URBs on close().

Note that the tty layer will wait up to 30 seconds for the buffers to
drain before close() is called.

Reviewed-by: Greg Kroah-Hartman <[e-mail]>
Signed-off-by: Johan Hovold <[e-mail]>

drivers/usb/serial/opticon.c

···
 	bool cts;
 	int outstanding_urbs;
 	int outstanding_bytes;
+
+	struct usb_anchor anchor;
 };
 
 
···
 	return res;
 }
 
+static void opticon_close(struct usb_serial_port *port)
+{
+	struct opticon_private *priv = usb_get_serial_port_data(port);
+
+	usb_kill_anchored_urbs(&priv->anchor);
+
+	usb_serial_generic_close(port);
+}
+
 static void opticon_write_control_callback(struct urb *urb)
 {
 	struct usb_serial_port *port = urb->context;
···
 		(unsigned char *)dr, buffer, count,
 		opticon_write_control_callback, port);
 
+	usb_anchor_urb(urb, &priv->anchor);
+
 	/* send it down the pipe */
 	ret = usb_submit_urb(urb, GFP_ATOMIC);
 	if (ret) {
 		dev_err(&port->dev, "failed to submit write urb: %d\n", ret);
+		usb_unanchor_urb(urb);
 		goto error;
 	}
 
···
 		return -ENOMEM;
 
 	spin_lock_init(&priv->lock);
+	init_usb_anchor(&priv->anchor);
 
 	usb_set_serial_port_data(port, priv);
 
···
 	.port_probe =		opticon_port_probe,
 	.port_remove =		opticon_port_remove,
 	.open =			opticon_open,
+	.close =		opticon_close,
 	.write =		opticon_write,
 	.write_room = 		opticon_write_room,
 	.chars_in_buffer =	opticon_chars_in_buffer,