diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index e554393d5551192997dc1048194b76bcc70b62e4..bcec4c71a408cd60832d1f1bcf4fdc32e174c777 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -186,8 +186,9 @@ static int pty_set_pktmode(struct tty_struct *tty, int __user *arg)
 	spin_lock_irq(&tty->ctrl_lock);
 	if (pktmode) {
 		if (!tty->packet) {
-			tty->packet = 1;
 			tty->link->ctrl_status = 0;
+			smp_mb();
+			tty->packet = 1;
 		}
 	} else
 		tty->packet = 0;