static long udmabuf_create()

in udmabuf.c [163:287]

• 118 lines of code
• 26 McCabe index (conditional complexity)

static long udmabuf_create(struct miscdevice *device,
			   struct udmabuf_create_list *head,
			   struct udmabuf_create_item *list)
{
	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
	struct file *memfd = NULL;
	struct address_space *mapping = NULL;
	struct udmabuf *ubuf;
	struct dma_buf *buf;
	pgoff_t pgoff, pgcnt, pgidx, pgbuf = 0, pglimit;
	struct page *page, *hpage = NULL;
	pgoff_t subpgoff, maxsubpgs;
	struct hstate *hpstate;
	int seals, ret = -EINVAL;
	u32 i, flags;

	ubuf = kzalloc(sizeof(*ubuf), GFP_KERNEL);
	if (!ubuf)
		return -ENOMEM;

	pglimit = (size_limit_mb * 1024 * 1024) >> PAGE_SHIFT;
	for (i = 0; i < head->count; i++) {
		if (!IS_ALIGNED(list[i].offset, PAGE_SIZE))
			goto err;
		if (!IS_ALIGNED(list[i].size, PAGE_SIZE))
			goto err;
		ubuf->pagecount += list[i].size >> PAGE_SHIFT;
		if (ubuf->pagecount > pglimit)
			goto err;
	}
	ubuf->pages = kmalloc_array(ubuf->pagecount, sizeof(*ubuf->pages),
				    GFP_KERNEL);
	if (!ubuf->pages) {
		ret = -ENOMEM;
		goto err;
	}

	pgbuf = 0;
	for (i = 0; i < head->count; i++) {
		ret = -EBADFD;
		memfd = fget(list[i].memfd);
		if (!memfd)
			goto err;
		mapping = file_inode(memfd)->i_mapping;
		if (!shmem_mapping(mapping) && !is_file_hugepages(memfd))
			goto err;
		seals = memfd_fcntl(memfd, F_GET_SEALS, 0);
		if (seals == -EINVAL)
			goto err;
		ret = -EINVAL;
		if ((seals & SEALS_WANTED) != SEALS_WANTED ||
		    (seals & SEALS_DENIED) != 0)
			goto err;
		pgoff = list[i].offset >> PAGE_SHIFT;
		pgcnt = list[i].size   >> PAGE_SHIFT;
		if (is_file_hugepages(memfd)) {
			hpstate = hstate_file(memfd);
			pgoff = list[i].offset >> huge_page_shift(hpstate);
			subpgoff = (list[i].offset &
				    ~huge_page_mask(hpstate)) >> PAGE_SHIFT;
			maxsubpgs = huge_page_size(hpstate) >> PAGE_SHIFT;
		}
		for (pgidx = 0; pgidx < pgcnt; pgidx++) {
			if (is_file_hugepages(memfd)) {
				if (!hpage) {
					hpage = find_get_page_flags(mapping, pgoff,
								    FGP_ACCESSED);
					if (!hpage) {
						ret = -EINVAL;
						goto err;
					}
				}
				page = hpage + subpgoff;
				get_page(page);
				subpgoff++;
				if (subpgoff == maxsubpgs) {
					put_page(hpage);
					hpage = NULL;
					subpgoff = 0;
					pgoff++;
				}
			} else {
				page = shmem_read_mapping_page(mapping,
							       pgoff + pgidx);
				if (IS_ERR(page)) {
					ret = PTR_ERR(page);
					goto err;
				}
			}
			ubuf->pages[pgbuf++] = page;
		}
		fput(memfd);
		memfd = NULL;
		if (hpage) {
			put_page(hpage);
			hpage = NULL;
		}
	}

	exp_info.ops  = &udmabuf_ops;
	exp_info.size = ubuf->pagecount << PAGE_SHIFT;
	exp_info.priv = ubuf;
	exp_info.flags = O_RDWR;

	ubuf->device = device;
	buf = dma_buf_export(&exp_info);
	if (IS_ERR(buf)) {
		ret = PTR_ERR(buf);
		goto err;
	}

	flags = 0;
	if (head->flags & UDMABUF_FLAGS_CLOEXEC)
		flags |= O_CLOEXEC;
	return dma_buf_fd(buf, flags);

err:
	while (pgbuf > 0)
		put_page(ubuf->pages[--pgbuf]);
	if (memfd)
		fput(memfd);
	kfree(ubuf->pages);
	kfree(ubuf);
	return ret;
}