UNP_BUSY
unp->unp_flags &= ~UNP_BUSY;
unp->unp_flags &= ~UNP_BUSY;
if ((unp->unp_flags & UNP_BUSY) != 0) {
unp->unp_flags |= UNP_BUSY;
unp->unp_flags &= ~UNP_BUSY;
if ((unp->unp_flags & UNP_BUSY) != 0) {
unp->unp_flags |= UNP_BUSY;