wqe_to_link
*wqe_to_link(wqe) = i + 1;
*wqe_to_link(wqe) = -1;
*wqe_to_link(last_free) = ind;
*wqe_to_link(get_wqe(srq, ind)) = -1;
next_ind = *wqe_to_link(wqe);
next_ind = *wqe_to_link(wqe);