Revert "tty: Fix ldisc crash on reopened tty"

This reverts commit 71472fa9.  It caused
merge issues, and Dmitry found some review issues.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Michael Neuling <mikey@neuling.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/tty_ldisc.c

@@ -669,17 +669,16 @@ int tty_ldisc_reinit(struct tty_struct *tty, int disc)
 		tty_ldisc_put(tty->ldisc);
 	}
 
+	/* switch the line discipline */
+	tty->ldisc = ld;
 	tty_set_termios_ldisc(tty, disc);
-	retval = tty_ldisc_open(tty, ld);
+	retval = tty_ldisc_open(tty, tty->ldisc);
 	if (retval) {
 		if (!WARN_ON(disc == N_TTY)) {
-			tty_ldisc_put(ld);
-			ld = NULL;
+			tty_ldisc_put(tty->ldisc);
+			tty->ldisc = NULL;
 		}
 	}
-
-	/* switch the line discipline */
-	smp_store_release(&tty->ldisc, ld);
 	return retval;
 }