Re: [PATCH v2] drm: Replace NULL with error value in drm_prime_pages_to_sg

[Oleksandr Andrushchenko]

On 06/18/2018 09:07 AM, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
>
> Dan Carpenter has reported that there is the following static checker
> warning:
> 	drivers/gpu/drm/drm_prime.c:317 drm_gem_map_dma_buf()
> 	warn: 'sgt' can also be NULL
>
> 314	sgt = obj->dev->driver->gem_prime_get_sg_table(obj);
> 315
> 316	if (!IS_ERR(sgt)) {
> 317		if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir,
>
> Problematic functions are xen_drm_front_gem_get_sg_table and
> drm_gem_cma_prime_get_sg_table. Fix those by replacing NULL with error value.
>
> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
> Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Dan, could you please review?
> ---
>   drivers/gpu/drm/drm_gem_cma_helper.c    | 2 +-
>   drivers/gpu/drm/xen/xen_drm_front_gem.c | 2 +-
>   2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
> index 80a5115c3846..ce868ce288fb 100644
> --- a/drivers/gpu/drm/drm_gem_cma_helper.c
> +++ b/drivers/gpu/drm/drm_gem_cma_helper.c
> @@ -436,7 +436,7 @@ struct sg_table *drm_gem_cma_prime_get_sg_table(struct drm_gem_object *obj)
>   
>   	sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
>   	if (!sgt)
> -		return NULL;
> +		return ERR_PTR(-ENOMEM);
>   
Forgot to patch CMA helpers, thus v2
>   	ret = dma_get_sgtable(obj->dev->dev, sgt, cma_obj->vaddr,
>   			      cma_obj->paddr, obj->size);
> diff --git a/drivers/gpu/drm/xen/xen_drm_front_gem.c b/drivers/gpu/drm/xen/xen_drm_front_gem.c
> index c85bfe7571cb..47ff019d3aef 100644
> --- a/drivers/gpu/drm/xen/xen_drm_front_gem.c
> +++ b/drivers/gpu/drm/xen/xen_drm_front_gem.c
> @@ -179,7 +179,7 @@ struct sg_table *xen_drm_front_gem_get_sg_table(struct drm_gem_object *gem_obj)
>   	struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj);
>   
>   	if (!xen_obj->pages)
> -		return NULL;
> +		return ERR_PTR(-ENOMEM);
>   
>   	return drm_prime_pages_to_sg(xen_obj->pages, xen_obj->num_pages);
>   }