[PATCH v2] drm: rcar-du: Fix leak of CMM platform device reference

[Laurent Pinchart]

Hi Jacopo,

On Wed, Dec 16, 2020 at 03:16:28PM +0100, Jacopo Mondi wrote:
> On Wed, Dec 16, 2020 at 04:08:36PM +0200, Laurent Pinchart wrote:
> > The device references acquired by of_find_device_by_node() are not
> > released by the driver. Fix this by registering a cleanup action.
> >
> > Fixes: 8de707aeb452 ("drm: rcar-du: kms: Initialize CMM instances")
> > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas at ideasonboard.com>
> > ---
> > Changes since v1:
> >
> > - Only set rcdu->cmms[] if the CMM config option is enabled
> > - Use platform_device_put()
> > ---
> >  drivers/gpu/drm/rcar-du/rcar_du_kms.c | 22 +++++++++++++++++++---
> >  1 file changed, 19 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/rcar-du/rcar_du_kms.c b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> > index 92dfa3d4c011..fdb8a0d127ad 100644
> > --- a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> > +++ b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> > @@ -14,6 +14,7 @@
> >  #include <drm/drm_fb_cma_helper.h>
> >  #include <drm/drm_gem_cma_helper.h>
> >  #include <drm/drm_gem_framebuffer_helper.h>
> > +#include <drm/drm_managed.h>
> >  #include <drm/drm_probe_helper.h>
> >  #include <drm/drm_vblank.h>
> >
> > @@ -726,8 +727,12 @@ static int rcar_du_cmm_init(struct rcar_du_device *rcdu)
> >  		 * disabled: return 0 and let the DU continue probing.
> >  		 */
> >  		ret = rcar_cmm_init(pdev);
> > -		if (ret)
> > +		if (ret) {
> > +			platform_device_put(pdev);
> >  			return ret == -ENODEV ? 0 : ret;
> > +		}
> > +
> > +		rcdu->cmms[i] = pdev;
> >
> >  		/*
> >  		 * Enforce suspend/resume ordering by making the CMM a provider
> 
> Sorry but don't we have an error path here below too, and if it fails
> -EINVAL is returned and the whole modeset_init() bails out without
> having put the platform device.

There's an error path below, but in that case rcdu->cmms[i] will be set
and the cleanup action will take care of it.

> > @@ -739,13 +744,20 @@ static int rcar_du_cmm_init(struct rcar_du_device *rcdu)
> >  				"Failed to create device link to CMM%u\n", i);
> >  			return -EINVAL;
> >  		}
> > -
> > -		rcdu->cmms[i] = pdev;
> >  	}
> >
> >  	return 0;
> >  }
> >
> > +static void rcar_du_modeset_cleanup(struct drm_device *dev, void *res)
> > +{
> > +	struct rcar_du_device *rcdu = to_rcar_du_device(dev);
> > +	unsigned int i;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(rcdu->cmms); ++i)
> > +		platform_device_put(rcdu->cmms[i]);
> > +}
> > +
> >  int rcar_du_modeset_init(struct rcar_du_device *rcdu)
> >  {
> >  	static const unsigned int mmio_offsets[] = {
> > @@ -766,6 +778,10 @@ int rcar_du_modeset_init(struct rcar_du_device *rcdu)
> >  	if (ret)
> >  		return ret;
> >
> > +	ret = drmm_add_action(&rcdu->ddev, rcar_du_modeset_cleanup, NULL);
> > +	if (ret)
> > +		return ret;
> > +
> >  	dev->mode_config.min_width = 0;
> >  	dev->mode_config.min_height = 0;
> >  	dev->mode_config.normalize_zpos = true;

-- 
Regards,

Laurent Pinchart