GET_Q_NEXT
rq->rqb_next_free = GET_Q_NEXT(free_index, 1, rq->cfg.nbufs);
rq->rqb_rc_head = GET_Q_NEXT(free_index, 1, rq->cfg.nbufs);
cur_index = GET_Q_NEXT(cur_index, 1, ring->num_items);
cur_index = GET_Q_NEXT(cur_index, 1, ring->num_items);
cur_index = GET_Q_NEXT(cur_index, 1, ring->num_items);
ring->cidx = GET_Q_NEXT(ring->cidx, n, ring->num_items)
ring->pidx = GET_Q_NEXT(ring->pidx, n, ring->num_items)