tty: compare the tty winsize

We always use the real tty one for stuff so the pty one should not be
compared. As we propagate window changes to both it doesn't currently
matter but will when we tidy up the pty termios logic a bit more
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/char/tty_io.c

@@ -2133,7 +2133,7 @@ int tty_do_resize(struct tty_struct *tty, struct tty_struct *real_tty,
 
 	/* For a PTY we need to lock the tty side */
 	mutex_lock(&real_tty->termios_mutex);
-	if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
+	if (!memcmp(ws, &real_tty->winsize, sizeof(*ws)))
 		goto done;
 	/* Get the PID values and reference them so we can
 	   avoid holding the tty ctrl lock while sending signals */