tty: Avoid unnecessary temporaries for tty->ldisc

tty_ldisc_setup() is race-free and can reference tty->ldisc without
snapshots.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/tty_ldisc.c

@@ -752,17 +752,14 @@ void tty_ldisc_hangup(struct tty_struct *tty, bool reinit)
 
 int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty)
 {
-	struct tty_ldisc *ld = tty->ldisc;
-	int retval;
-
-	retval = tty_ldisc_open(tty, ld);
+	int retval = tty_ldisc_open(tty, tty->ldisc);
 	if (retval)
 		return retval;
 
 	if (o_tty) {
 		retval = tty_ldisc_open(o_tty, o_tty->ldisc);
 		if (retval) {
-			tty_ldisc_close(tty, ld);
+			tty_ldisc_close(tty, tty->ldisc);
 			return retval;
 		}
 	}