HN_TX_FLAG_ATTACHED
KASSERT((txr->hn_tx_flags & HN_TX_FLAG_ATTACHED) == 0,
txr->hn_tx_flags |= HN_TX_FLAG_ATTACHED;
KASSERT((txr->hn_tx_flags & HN_TX_FLAG_ATTACHED),
txr->hn_tx_flags &= ~HN_TX_FLAG_ATTACHED;
HN_TX_FLAG_ATTACHED) == 0,