MBOX_MQ_ID_MASK
return MBOX_MQ_ID_MASK(mq, (mq)->prod_idx + 1) ==
MBOX_MQ_ID_MASK(mq, (mq)->cons_idx);
mq->prod_idx, MBOX_MQ_ID_MASK(mq, mq->cons_idx));
mq->prod_idx = MBOX_MQ_ID_MASK(mq, mq->prod_idx);