[PATCH] drm: Zero out DRM object memory upon cleanup

[Daniel Vetter]

On Wed, Dec 10, 2014 at 11:38:49AM +0100, Thierry Reding wrote:
> From: Thierry Reding <treding at nvidia.com>
> 
> Drivers where the DRM objects have a lifetime that extends beyond that
> of the DRM device need to zero out the DRM object memory to void stale
> data such as properties. The DRM core code expects to operate on newly
> allocated and zeroed out objects and will behave unexpectedly, such as
> add duplicate properties, otherwise.
> 
> Signed-off-by: Thierry Reding <treding at nvidia.com>

Yeah, makes sense imo to do in the core. Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

Also stuffed into drm-misc and I think I'll throw that at Dave today or
tomorrow.
-Daniel

> ---
>  drivers/gpu/drm/drm_crtc.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index 4c9aaf8e6176..4e35d2f74e0f 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -725,6 +725,8 @@ void drm_crtc_cleanup(struct drm_crtc *crtc)
>  	WARN_ON(crtc->state && !crtc->funcs->atomic_destroy_state);
>  	if (crtc->state && crtc->funcs->atomic_destroy_state)
>  		crtc->funcs->atomic_destroy_state(crtc, crtc->state);
> +
> +	memset(crtc, 0, sizeof(*crtc));
>  }
>  EXPORT_SYMBOL(drm_crtc_cleanup);
>  
> @@ -927,6 +929,8 @@ void drm_connector_cleanup(struct drm_connector *connector)
>  	if (connector->state && connector->funcs->atomic_destroy_state)
>  		connector->funcs->atomic_destroy_state(connector,
>  						       connector->state);
> +
> +	memset(connector, 0, sizeof(*connector));
>  }
>  EXPORT_SYMBOL(drm_connector_cleanup);
>  
> @@ -1068,6 +1072,8 @@ void drm_bridge_cleanup(struct drm_bridge *bridge)
>  	list_del(&bridge->head);
>  	dev->mode_config.num_bridge--;
>  	drm_modeset_unlock_all(dev);
> +
> +	memset(bridge, 0, sizeof(*bridge));
>  }
>  EXPORT_SYMBOL(drm_bridge_cleanup);
>  
> @@ -1134,10 +1140,11 @@ void drm_encoder_cleanup(struct drm_encoder *encoder)
>  	drm_modeset_lock_all(dev);
>  	drm_mode_object_put(dev, &encoder->base);
>  	kfree(encoder->name);
> -	encoder->name = NULL;
>  	list_del(&encoder->head);
>  	dev->mode_config.num_encoder--;
>  	drm_modeset_unlock_all(dev);
> +
> +	memset(encoder, 0, sizeof(*encoder));
>  }
>  EXPORT_SYMBOL(drm_encoder_cleanup);
>  
> @@ -1257,6 +1264,8 @@ void drm_plane_cleanup(struct drm_plane *plane)
>  	WARN_ON(plane->state && !plane->funcs->atomic_destroy_state);
>  	if (plane->state && plane->funcs->atomic_destroy_state)
>  		plane->funcs->atomic_destroy_state(plane, plane->state);
> +
> +	memset(plane, 0, sizeof(*plane));
>  }
>  EXPORT_SYMBOL(drm_plane_cleanup);
>  
> -- 
> 2.1.3
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch