[PATCH 3/3] drm/prime: Use anon_drm_getfile() for an internal drm struct file

[Daniel Vetter]

On Wed, Nov 06, 2019 at 10:07:16AM +0000, Chris Wilson wrote:
> Currently the drm_prime mmap fallback uses a mock struct file to provide
> the file pointer into the backend mmap routine. Now that we can create
> fully fledged anonymous struct file around the drm device, put it to
> use.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/drm_prime.c | 26 ++++++++------------------
>  1 file changed, 8 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
> index 0814211b0f3f..5faa63713ec8 100644
> --- a/drivers/gpu/drm/drm_prime.c
> +++ b/drivers/gpu/drm/drm_prime.c
> @@ -709,8 +709,7 @@ EXPORT_SYMBOL(drm_gem_dmabuf_vunmap);
>   */
>  int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
>  {
> -	struct drm_file *priv;
> -	struct file *fil;
> +	struct file *file;
>  	int ret;
>  
>  	if (obj->funcs && obj->funcs->mmap) {

obj->funcs->mmap is the new way of doing this (and hopefully finally
something clean), I'd really like to retire the below hack outright.

Plus I'm not sure why you need an anon inode here? If a driver needs this
for unmap_mapping_range or similar I think it'd be better to try and make
something work cleanly for obj->funcs->mmap.
-Daniel

> @@ -722,30 +721,21 @@ int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
>  		return 0;
>  	}
>  
> -	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> -	fil = kzalloc(sizeof(*fil), GFP_KERNEL);
> -	if (!priv || !fil) {
> -		ret = -ENOMEM;
> -		goto out;
> -	}
> +	file = anon_drm_getfile(obj->dev->primary, O_RDWR);
> +	if (IS_ERR(file))
> +		return PTR_ERR(file);
>  
> -	/* Used by drm_gem_mmap() to lookup the GEM object */
> -	priv->minor = obj->dev->primary;
> -	fil->private_data = priv;
> -
> -	ret = drm_vma_node_allow(&obj->vma_node, priv);
> +	ret = drm_vma_node_allow(&obj->vma_node, file->private_data);
>  	if (ret)
>  		goto out;
>  
>  	vma->vm_pgoff += drm_vma_node_start(&obj->vma_node);
>  
> -	ret = obj->dev->driver->fops->mmap(fil, vma);
> +	ret = file->f_op->mmap(file, vma);
>  
> -	drm_vma_node_revoke(&obj->vma_node, priv);
> +	drm_vma_node_revoke(&obj->vma_node, file->private_data);
>  out:
> -	kfree(priv);
> -	kfree(fil);
> -
> +	fput(file);
>  	return ret;
>  }
>  EXPORT_SYMBOL(drm_gem_prime_mmap);
> -- 
> 2.24.0
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch