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

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

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;
> +}


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