static int __nvme_alloc_host_mem()

in host/pci.c [2020:2086]

• 55 lines of code
• 10 McCabe index (conditional complexity)

static int __nvme_alloc_host_mem(struct nvme_dev *dev, u64 preferred,
		u32 chunk_size)
{
	struct nvme_host_mem_buf_desc *descs;
	u32 max_entries, len;
	dma_addr_t descs_dma;
	int i = 0;
	void **bufs;
	u64 size, tmp;

	tmp = (preferred + chunk_size - 1);
	do_div(tmp, chunk_size);
	max_entries = tmp;

	if (dev->ctrl.hmmaxd && dev->ctrl.hmmaxd < max_entries)
		max_entries = dev->ctrl.hmmaxd;

	descs = dma_alloc_coherent(dev->dev, max_entries * sizeof(*descs),
				   &descs_dma, GFP_KERNEL);
	if (!descs)
		goto out;

	bufs = kcalloc(max_entries, sizeof(*bufs), GFP_KERNEL);
	if (!bufs)
		goto out_free_descs;

	for (size = 0; size < preferred && i < max_entries; size += len) {
		dma_addr_t dma_addr;

		len = min_t(u64, chunk_size, preferred - size);
		bufs[i] = dma_alloc_attrs(dev->dev, len, &dma_addr, GFP_KERNEL,
				DMA_ATTR_NO_KERNEL_MAPPING | DMA_ATTR_NO_WARN);
		if (!bufs[i])
			break;

		descs[i].addr = cpu_to_le64(dma_addr);
		descs[i].size = cpu_to_le32(len / NVME_CTRL_PAGE_SIZE);
		i++;
	}

	if (!size)
		goto out_free_bufs;

	dev->nr_host_mem_descs = i;
	dev->host_mem_size = size;
	dev->host_mem_descs = descs;
	dev->host_mem_descs_dma = descs_dma;
	dev->host_mem_desc_bufs = bufs;
	return 0;

out_free_bufs:
	while (--i >= 0) {
		size_t size = le32_to_cpu(descs[i].size) * NVME_CTRL_PAGE_SIZE;

		dma_free_attrs(dev->dev, size, bufs[i],
			       le64_to_cpu(descs[i].addr),
			       DMA_ATTR_NO_KERNEL_MAPPING | DMA_ATTR_NO_WARN);
	}

	kfree(bufs);
out_free_descs:
	dma_free_coherent(dev->dev, max_entries * sizeof(*descs), descs,
			descs_dma);
out:
	dev->host_mem_descs = NULL;
	return -ENOMEM;
}