[PATCH 1/2] drm/property: Enforce more lifetime rules

[Jani Nikula]

On Wed, 23 Oct 2019, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
> Properties can't be attached after registering, userspace would get
> confused (no one bothers to reprobe really).
>
> - Add kerneldoc
> - Enforce this with some checks. This needs a somewhat ugly check
>   since connectors can be added later on, but we still need to attach
>   all properties before they go public.
>
> Note that we already enforce that properties themselves are created
> before the entire device is registered.
>
> Cc: Jani Nikula <jani.nikula at linux.intel.com>
> Cc: Rajat Jain <rajatja at google.com>
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> ---
>  drivers/gpu/drm/drm_mode_object.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_mode_object.c b/drivers/gpu/drm/drm_mode_object.c
> index 6a23e36ed4fe..35c2719407a8 100644
> --- a/drivers/gpu/drm/drm_mode_object.c
> +++ b/drivers/gpu/drm/drm_mode_object.c
> @@ -224,12 +224,26 @@ EXPORT_SYMBOL(drm_mode_object_get);
>   * This attaches the given property to the modeset object with the given initial
>   * value. Currently this function cannot fail since the properties are stored in
>   * a statically sized array.
> + *
> + * Note that all properties must be attached before the object itself is
> + * registered and accessible from userspace.
>   */
>  void drm_object_attach_property(struct drm_mode_object *obj,
>  				struct drm_property *property,
>  				uint64_t init_val)
>  {
>  	int count = obj->properties->count;
> +	struct drm_device *dev = property->dev;
> +
> +

Superfluous newline, with that fixed,

Reviewed-by: Jani Nikula <jani.nikula at intel.com>

> +	if (obj->type == DRM_MODE_OBJECT_CONNECTOR) {
> +		struct drm_connector *connector = obj_to_connector(obj);
> +
> +		WARN_ON(!dev->driver->load &&
> +			connector->registration_state == DRM_CONNECTOR_REGISTERED);
> +	} else {
> +		WARN_ON(!dev->driver->load && dev->registered);
> +	}
>  
>  	if (count == DRM_OBJECT_MAX_PROPERTY) {
>  		WARN(1, "Failed to attach object property (type: 0x%x). Please "

-- 
Jani Nikula, Intel Open Source Graphics Center