Re: [PATCH v2 1/9] drm: atmel-hlcdc: add a ->cleanup_fb() operation

[Boris Brezillon]

Hi Daniel,

On Wed, 16 Mar 2016 16:17:38 +0100
Daniel Vetter <daniel@xxxxxxxx> wrote:

> 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@xxxxxxxxxxxxxxxxxx>
> > Fixes 2389fc1 ("drm: atmel-hlcdc: Atomic mode-setting conversion")
> > Reviewed-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
> > Tested-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
> > ---
> >  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.

Hm, it's not exactly encoding the same thing. What I want to do here is
call atmel_hlcdc_layer_update_rollback() only if the atomic update has
failed (see below, I set ->prepared back to false in the
->atomic_update() method). AFAICT, ->cleanup_fb() is also called
when the whole operation succeed (and in this case I don't want to
call atmel_hlcdc_layer_update_rollback()).

Let me know if you see a better approach to do that.

Thanks,

Boris

> -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
> > 
> 



-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com