queue_inc_prod_n
llq.prod = queue_inc_prod_n(&llq, limit - sbidx);
llq->cons = ret ? llq->prod : queue_inc_prod_n(llq, 1);
prod = queue_inc_prod_n(&llq, i);
head.prod = queue_inc_prod_n(&llq, n + sync) |
prod = queue_inc_prod_n(&llq, n);
llq.prod = queue_inc_prod_n(&llq, n);