DO_HEAD_DEQ
DO_HEAD_DEQ(_r_,_q_); \
DO_HEAD_DEQ(req2, queue);
DO_HEAD_DEQ(req, &sstfq->right);
DO_HEAD_DEQ(req, &scanq->right);
DO_HEAD_DEQ(req, &scanq->right);
DO_HEAD_DEQ(req, &cscanq->right);
DO_HEAD_DEQ(req, &cscanq->right);