diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index b72fa49..e4eca78 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -686,15 +686,21 @@
 
 	/* Perform the closing process and see if we need to do the hardware
 	   shutdown */
-	if (!acm || tty_port_close_start(&acm->port, tty, filp) == 0)
+	if (!acm)
 		return;
+	if (tty_port_close_start(&acm->port, tty, filp) == 0) {
+		mutex_lock(&open_mutex);
+		if (!acm->dev) {
+			tty_port_tty_set(&acm->port, NULL);
+			acm_tty_unregister(acm);
+			tty->driver_data = NULL;
+		}
+		mutex_unlock(&open_mutex);
+		return;
+	}
 	acm_port_down(acm, 0);
 	tty_port_close_end(&acm->port, tty);
-	mutex_lock(&open_mutex);
 	tty_port_tty_set(&acm->port, NULL);
-	if (!acm->dev)
-		acm_tty_unregister(acm);
-	mutex_unlock(&open_mutex);
 }
 
 static int acm_tty_write(struct tty_struct *tty,