[PATCH] drm: set DRM_RENDER_ALLOW flag on DRM_IOCTL_MODE_CREATE/DESTROY_DUMB ioctls

[Daniel Vetter]

On Thu, Jun 10, 2021 at 02:36:59PM -0700, Dongwon Kim wrote:
> Render clients should be able to create/destroy dumb object to import
> and use it as render buffer in case the default DRM device is different
> from the render device (i.e. kmsro).
> 
> Signed-off-by: Dongwon Kim <dongwon.kim at intel.com>

Uh no.

Well I know everyone just hacks around this, but the idea behind dumb
buffer objects is that they're for kms scanout only. Furthermore on many
drivers they allocate a limited resource like CMA memory. Handing that out
like candy isn't a great idea.

And it's exactly those drivers that kmsro currently is used for where the
display driver needs special memory.
-Daniel

> ---
>  drivers/gpu/drm/drm_ioctl.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
> index 98ae00661656..f2f72e132741 100644
> --- a/drivers/gpu/drm/drm_ioctl.c
> +++ b/drivers/gpu/drm/drm_ioctl.c
> @@ -685,9 +685,9 @@ static const struct drm_ioctl_desc drm_ioctls[] = {
>  	DRM_IOCTL_DEF(DRM_IOCTL_MODE_RMFB, drm_mode_rmfb_ioctl, 0),
>  	DRM_IOCTL_DEF(DRM_IOCTL_MODE_PAGE_FLIP, drm_mode_page_flip_ioctl, DRM_MASTER),
>  	DRM_IOCTL_DEF(DRM_IOCTL_MODE_DIRTYFB, drm_mode_dirtyfb_ioctl, DRM_MASTER),
> -	DRM_IOCTL_DEF(DRM_IOCTL_MODE_CREATE_DUMB, drm_mode_create_dumb_ioctl, 0),
> +	DRM_IOCTL_DEF(DRM_IOCTL_MODE_CREATE_DUMB, drm_mode_create_dumb_ioctl, DRM_RENDER_ALLOW),
>  	DRM_IOCTL_DEF(DRM_IOCTL_MODE_MAP_DUMB, drm_mode_mmap_dumb_ioctl, 0),
> -	DRM_IOCTL_DEF(DRM_IOCTL_MODE_DESTROY_DUMB, drm_mode_destroy_dumb_ioctl, 0),
> +	DRM_IOCTL_DEF(DRM_IOCTL_MODE_DESTROY_DUMB, drm_mode_destroy_dumb_ioctl, DRM_RENDER_ALLOW),
>  	DRM_IOCTL_DEF(DRM_IOCTL_MODE_OBJ_GETPROPERTIES, drm_mode_obj_get_properties_ioctl, 0),
>  	DRM_IOCTL_DEF(DRM_IOCTL_MODE_OBJ_SETPROPERTY, drm_mode_obj_set_property_ioctl, DRM_MASTER),
>  	DRM_IOCTL_DEF(DRM_IOCTL_MODE_CURSOR2, drm_mode_cursor2_ioctl, DRM_MASTER),
> -- 
> 2.20.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch