diff --git a/[refs] b/[refs]
index 0489b151f2d5..4dc8c3668214 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 762faaed91e4ea4a3c34bc58f3221d9487acb470
+refs/heads/master: 1aa4bed82a684308f54bf782cffaecd4b1dc3cf4
diff --git a/trunk/drivers/char/tty_io.c b/trunk/drivers/char/tty_io.c
index 939e198d7670..a3afa0c387cd 100644
--- a/trunk/drivers/char/tty_io.c
+++ b/trunk/drivers/char/tty_io.c
@@ -1263,7 +1263,9 @@ static int tty_reopen(struct tty_struct *tty)
 	tty->count++;
 	tty->driver = driver; /* N.B. why do this every time?? */
 
+	mutex_lock(&tty->ldisc_mutex);
 	WARN_ON(!test_bit(TTY_LDISC, &tty->flags));
+	mutex_unlock(&tty->ldisc_mutex);
 
 	return 0;
 }