static blk_status_t nvme_pci_setup_prps()

in host/pci.c [625:715]

• 86 lines of code
• 12 McCabe index (conditional complexity)

static blk_status_t nvme_pci_setup_prps(struct nvme_dev *dev,
		struct request *req, struct nvme_rw_command *cmnd)
{
	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
	struct dma_pool *pool;
	int length = blk_rq_payload_bytes(req);
	struct scatterlist *sg = iod->sg;
	int dma_len = sg_dma_len(sg);
	u64 dma_addr = sg_dma_address(sg);
	int offset = dma_addr & (NVME_CTRL_PAGE_SIZE - 1);
	__le64 *prp_list;
	void **list = nvme_pci_iod_list(req);
	dma_addr_t prp_dma;
	int nprps, i;

	length -= (NVME_CTRL_PAGE_SIZE - offset);
	if (length <= 0) {
		iod->first_dma = 0;
		goto done;
	}

	dma_len -= (NVME_CTRL_PAGE_SIZE - offset);
	if (dma_len) {
		dma_addr += (NVME_CTRL_PAGE_SIZE - offset);
	} else {
		sg = sg_next(sg);
		dma_addr = sg_dma_address(sg);
		dma_len = sg_dma_len(sg);
	}

	if (length <= NVME_CTRL_PAGE_SIZE) {
		iod->first_dma = dma_addr;
		goto done;
	}

	nprps = DIV_ROUND_UP(length, NVME_CTRL_PAGE_SIZE);
	if (nprps <= (256 / 8)) {
		pool = dev->prp_small_pool;
		iod->npages = 0;
	} else {
		pool = dev->prp_page_pool;
		iod->npages = 1;
	}

	prp_list = dma_pool_alloc(pool, GFP_ATOMIC, &prp_dma);
	if (!prp_list) {
		iod->first_dma = dma_addr;
		iod->npages = -1;
		return BLK_STS_RESOURCE;
	}
	list[0] = prp_list;
	iod->first_dma = prp_dma;
	i = 0;
	for (;;) {
		if (i == NVME_CTRL_PAGE_SIZE >> 3) {
			__le64 *old_prp_list = prp_list;
			prp_list = dma_pool_alloc(pool, GFP_ATOMIC, &prp_dma);
			if (!prp_list)
				goto free_prps;
			list[iod->npages++] = prp_list;
			prp_list[0] = old_prp_list[i - 1];
			old_prp_list[i - 1] = cpu_to_le64(prp_dma);
			i = 1;
		}
		prp_list[i++] = cpu_to_le64(dma_addr);
		dma_len -= NVME_CTRL_PAGE_SIZE;
		dma_addr += NVME_CTRL_PAGE_SIZE;
		length -= NVME_CTRL_PAGE_SIZE;
		if (length <= 0)
			break;
		if (dma_len > 0)
			continue;
		if (unlikely(dma_len < 0))
			goto bad_sgl;
		sg = sg_next(sg);
		dma_addr = sg_dma_address(sg);
		dma_len = sg_dma_len(sg);
	}
done:
	cmnd->dptr.prp1 = cpu_to_le64(sg_dma_address(iod->sg));
	cmnd->dptr.prp2 = cpu_to_le64(iod->first_dma);
	return BLK_STS_OK;
free_prps:
	nvme_free_prps(dev, req);
	return BLK_STS_RESOURCE;
bad_sgl:
	WARN(DO_ONCE(nvme_print_sgl, iod->sg, iod->nents),
			"Invalid SGL for payload:%d nents:%d\n",
			blk_rq_payload_bytes(req), iod->nents);
	return BLK_STS_IOERR;
}