SACK_NOCHANGE
sack_changed = SACK_NOCHANGE;
if ((sack_changed != SACK_NOCHANGE) &&
if (sack_changed == SACK_NOCHANGE) {
(((tp->t_rxtshift == 0) && (sack_changed != SACK_NOCHANGE)) ||
sack_changed = SACK_NOCHANGE;
sack_changed = SACK_NOCHANGE;