Re: [PATCH 5/9] drm/xen-front: Implement handling of shared display buffers

On 02/21/2018 03:03 AM, Oleksandr Andrushchenko wrote:

static int __init xen_drv_init(void) {

• /* At the moment we only support case with XEN_PAGE_SIZE == PAGE_SIZE */
• BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);

Why BUILD_BUG_ON? This should simply not load if page sizes are different.

• ret = gnttab_map_refs(map_ops, NULL, buf->pages, buf->num_pages);
• BUG_ON(ret);

We should try not to BUG*(). There are a few in this patch (and possibly others) that I think can be avoided.

+static int alloc_storage(struct xen_drm_front_shbuf *buf) +{

• if (buf->sgt) {

• buf->pages = kvmalloc_array(buf->num_pages,
  

• 		sizeof(struct page *), GFP_KERNEL);
  

• if (!buf->pages)
  

• 	return -ENOMEM;
  

• if (drm_prime_sg_to_page_addr_arrays(buf->sgt, buf->pages,
  

• 		NULL, buf->num_pages) < 0)
  

• 	return -EINVAL;
  

• }
• buf->grefs = kcalloc(buf->num_grefs, sizeof(*buf->grefs), GFP_KERNEL);
• if (!buf->grefs)

• return -ENOMEM;
  

• buf->directory = kcalloc(get_num_pages_dir(buf), PAGE_SIZE, GFP_KERNEL);
• if (!buf->directory)

• return -ENOMEM;
  

You need to clean up on errors.

-boris

• return 0;

+}