X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=drivers%2Ftty%2Ftty_ldisc.c;h=3737f55272d2c1184463edc3714f89fb2724730e;hb=93d76c802644e0cab62545603381988cef84d1d7;hp=b66a81d0549e3171420ae948ec3a24ef74987836;hpb=28e1445c650035668514df6f446c81f89990ac52;p=firefly-linux-kernel-4.4.55.git

diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index b66a81d0549e..3737f55272d2 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -572,8 +572,11 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 		tty_ldisc_restore(tty, old_ldisc);
 	}
 
-	if (tty->ldisc->ops->num != old_ldisc->ops->num && tty->ops->set_ldisc)
+	if (tty->ldisc->ops->num != old_ldisc->ops->num && tty->ops->set_ldisc) {
+		down_read(&tty->termios_rwsem);
 		tty->ops->set_ldisc(tty);
+		up_read(&tty->termios_rwsem);
+	}
 
 	/* At this point we hold a reference to the new ldisc and a
 	   reference to the old ldisc, or we hold two references to