Re: [PATCH] drm/drm_ioctl.c: Test client capability value early when setting.

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Feb 28, 2018 at 03:27:41PM +0000, Liviu Dudau wrote:
> The drm_setclientcap() function implementing the DRM_IOCTL_SET_CLIENT_CAP
> ioctl expects that any capability set by the client will have a value of 1.
> Make the check early so that we don't have to test the value for each
> capability.

What if we want a a non-boolean capability at some point?

> 
> Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>
> ---
>  drivers/gpu/drm/drm_ioctl.c | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
> index af782911c505..02ffa0e8d77b 100644
> --- a/drivers/gpu/drm/drm_ioctl.c
> +++ b/drivers/gpu/drm/drm_ioctl.c
> @@ -306,22 +306,19 @@ drm_setclientcap(struct drm_device *dev, void *data, struct drm_file *file_priv)
>  {
>  	struct drm_set_client_cap *req = data;
>  
> +	if (req->value > 1)
> +		return -EINVAL;
> +
>  	switch (req->capability) {
>  	case DRM_CLIENT_CAP_STEREO_3D:
> -		if (req->value > 1)
> -			return -EINVAL;
>  		file_priv->stereo_allowed = req->value;
>  		break;
>  	case DRM_CLIENT_CAP_UNIVERSAL_PLANES:
> -		if (req->value > 1)
> -			return -EINVAL;
>  		file_priv->universal_planes = req->value;
>  		break;
>  	case DRM_CLIENT_CAP_ATOMIC:
>  		if (!drm_core_check_feature(dev, DRIVER_ATOMIC))
>  			return -EINVAL;
> -		if (req->value > 1)
> -			return -EINVAL;
>  		file_priv->atomic = req->value;
>  		file_priv->universal_planes = req->value;
>  		break;
> -- 
> 2.16.2
> 
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-- 
Ville Syrjälä
Intel OTC