linux-kernel - Re: [PATCH v2 1/9] drm: atmel-hlcdc: add a ->cleanup

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Message-ID: <20160316151738.GQ14170@phenom.ffwll.local>
Date:	Wed, 16 Mar 2016 16:17:38 +0100
From:	Daniel Vetter <daniel@...ll.ch>
To:	Boris Brezillon <boris.brezillon@...e-electrons.com>
Cc:	David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>,
	dri-devel@...ts.freedesktop.org,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/9] drm: atmel-hlcdc: add a ->cleanup_fb() operation

On Wed, Mar 16, 2016 at 02:57:35PM +0100, Boris Brezillon wrote:
> Add a ->cleanup_fb() operation to avoid memory leaks when the atomic
> operation is interrupted after the ->prepare_fb() call.
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
> Fixes 2389fc1 ("drm: atmel-hlcdc: Atomic mode-setting conversion")
> Reviewed-by: Nicolas Ferre <nicolas.ferre@...el.com>
> Tested-by: Nicolas Ferre <nicolas.ferre@...el.com>
> ---
>  drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h    |  2 ++
>  drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c | 22 +++++++++++++++++++---
>  2 files changed, 21 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
> index fed517f..ec64140 100644
> --- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
> +++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
> @@ -81,11 +81,13 @@ struct atmel_hlcdc_plane_properties {
>   * @layer: HLCDC layer structure
>   * @properties: pointer to the property definitions structure
>   * @rotation: current rotation status
> + * @prepared: flagging the plane has prepared for an atomic update
>   */
>  struct atmel_hlcdc_plane {
>  	struct drm_plane base;
>  	struct atmel_hlcdc_layer layer;
>  	struct atmel_hlcdc_plane_properties *properties;
> +	bool prepared;
>  };
>  
>  static inline struct atmel_hlcdc_plane *
> diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c
> index 1ffe9c3..35027d0 100644
> --- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c
> +++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c
> @@ -715,11 +715,25 @@ static int atmel_hlcdc_plane_prepare_fb(struct drm_plane *p,
>  					const struct drm_plane_state *new_state)
>  {
>  	struct atmel_hlcdc_plane *plane = drm_plane_to_atmel_hlcdc_plane(p);
> +	int ret;
>  
> -	if (!new_state->fb)
> -		return 0;
> +	ret = atmel_hlcdc_layer_update_start(&plane->layer);
> +	if (!ret)
> +		plane->prepared = true;

Atomic helpers will keep track of this for you, and only call ->cleanup_fb
on a plane combo where it did (successfully) call ->prepare_fb.
-Daniel

> +
> +	return ret;
> +}
> +
> +static void atmel_hlcdc_plane_cleanup_fb(struct drm_plane *p,
> +				const struct drm_plane_state *old_state)
> +{
> +	struct atmel_hlcdc_plane *plane = drm_plane_to_atmel_hlcdc_plane(p);
> +
> +	if (!plane->prepared)
> +		return;
>  
> -	return atmel_hlcdc_layer_update_start(&plane->layer);
> +	atmel_hlcdc_layer_update_rollback(&plane->layer);
> +	plane->prepared = false;
>  }
>  
>  static void atmel_hlcdc_plane_atomic_update(struct drm_plane *p,
> @@ -739,6 +753,7 @@ static void atmel_hlcdc_plane_atomic_update(struct drm_plane *p,
>  	atmel_hlcdc_plane_update_disc_area(plane, state);
>  
>  	atmel_hlcdc_layer_update_commit(&plane->layer);
> +	plane->prepared = false;
>  }
>  
>  static void atmel_hlcdc_plane_atomic_disable(struct drm_plane *p,
> @@ -844,6 +859,7 @@ static void atmel_hlcdc_plane_init_properties(struct atmel_hlcdc_plane *plane,
>  
>  static struct drm_plane_helper_funcs atmel_hlcdc_layer_plane_helper_funcs = {
>  	.prepare_fb = atmel_hlcdc_plane_prepare_fb,
> +	.cleanup_fb = atmel_hlcdc_plane_cleanup_fb,
>  	.atomic_check = atmel_hlcdc_plane_atomic_check,
>  	.atomic_update = atmel_hlcdc_plane_atomic_update,
>  	.atomic_disable = atmel_hlcdc_plane_atomic_disable,
> -- 
> 2.5.0
> 

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