diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 28315b0..3ce98e8 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -634,6 +634,7 @@
 	serial->type = driver;
 	serial->interface = interface;
 	kref_init(&serial->kref);
+	mutex_init(&serial->disc_mutex);
 
 	return serial;
 }
@@ -1089,20 +1090,22 @@
 	usb_serial_console_disconnect(serial);
 	dbg ("%s", __FUNCTION__);
 
+	mutex_lock(&serial->disc_mutex);
 	usb_set_intfdata (interface, NULL);
-	if (serial) {
-		for (i = 0; i < serial->num_ports; ++i) {
-			port = serial->port[i];
-			if (port) {
-				if (port->tty)
-					tty_hangup(port->tty);
-				kill_traffic(port);
-			}
+	/* must set a flag, to signal subdrivers */
+	serial->disconnected = 1;
+	for (i = 0; i < serial->num_ports; ++i) {
+		port = serial->port[i];
+		if (port) {
+			if (port->tty)
+				tty_hangup(port->tty);
+			kill_traffic(port);
 		}
-		/* let the last holder of this object 
-		 * cause it to be cleaned up */
-		usb_serial_put(serial);
 	}
+	/* let the last holder of this object
+	 * cause it to be cleaned up */
+	mutex_unlock(&serial->disc_mutex);
+	usb_serial_put(serial);
 	dev_info(dev, "device disconnected\n");
 }
 
@@ -1112,9 +1115,6 @@
 	struct usb_serial_port *port;
 	int i, r = 0;
 
-	if (!serial) /* device has been disconnected */
-		return 0;
-
 	for (i = 0; i < serial->num_ports; ++i) {
 		port = serial->port[i];
 		if (port)