LOG_SIZE
cb->head = CIRC_ADD(cb->head, LOG_SIZE, 1);
while (!CIRC_CNT(cb->head, cb->tail, LOG_SIZE)) {
CIRC_CNT(cb->head, cb->tail, LOG_SIZE));
ret = min_t(size_t, CIRC_CNT_TO_END(cb->head, cb->tail, LOG_SIZE),
cb->tail = CIRC_ADD(cb->tail, LOG_SIZE, ret);
LOG_SIZE))
buf = devm_kzalloc(ec->dev, LOG_SIZE, GFP_KERNEL);
buf_space = CIRC_SPACE(cb->head, cb->tail, LOG_SIZE);