[PATCH] drm: Wrap direct calls to driver->gem_free_object from CMA

[Robert Foss]

Verified working on rpi2.

Tested-by: Robert Foss <robert.foss at collabora.com>

On 2016-05-31 05:25 PM, Chris Wilson wrote:
> Since the introduction of (struct_mutex) lockless GEM bo freeing, there
> are a pair of driver vfuncs for freeing the GEM bo, of which the driver
> may choose to only implement driver->gem_object_free_unlocked (and so
> avoid taking the struct_mutex along the free path). However, the CMA GEM
> helpers were still calling driver->gem_free_object directly, now NULL,
> and promptly dying on the fancy new lockless drivers. Oops.
>
> Robert Foss bisected this to b82caafcf2303 (drm/vc4: Use lockless gem BO
> free callback) on his vc4 device, but that just serves as an enabler for
> 9f0ba539d13ae (drm/gem: support BO freeing without dev->struct_mutex).
>
> Reported-by: Robert Foss <robert.foss at collabora.com>
> Fixes: 9f0ba539d13ae (drm/gem: support BO freeing without dev->struct_mutex)
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Robert Foss <robert.foss at collabora.com>
> Cc: Daniel Vetter <daniel.vetter at intel.com>
> Cc: Eric Anholt <eric at anholt.net>
> Cc: Alex Deucher <alexdeucher at gmail.com>
> Cc: Lucas Stach <l.stach at pengutronix.de>
> Cc: stable at vger.kernel.org
> ---
>   drivers/gpu/drm/drm_fb_cma_helper.c  |  2 +-
>   drivers/gpu/drm/drm_gem_cma_helper.c | 12 +++---------
>   2 files changed, 4 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c b/drivers/gpu/drm/drm_fb_cma_helper.c
> index 172cafe11c71..5075fae3c4e2 100644
> --- a/drivers/gpu/drm/drm_fb_cma_helper.c
> +++ b/drivers/gpu/drm/drm_fb_cma_helper.c
> @@ -445,7 +445,7 @@ err_cma_destroy:
>   err_fb_info_destroy:
>   	drm_fb_helper_release_fbi(helper);
>   err_gem_free_object:
> -	dev->driver->gem_free_object(&obj->base);
> +	drm_gem_object_unreference_unlocked(&obj->base);
>   	return ret;
>   }
>   EXPORT_SYMBOL(drm_fbdev_cma_create_with_funcs);
> diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
> index e1ab008b3f08..1d6c335584ec 100644
> --- a/drivers/gpu/drm/drm_gem_cma_helper.c
> +++ b/drivers/gpu/drm/drm_gem_cma_helper.c
> @@ -121,7 +121,7 @@ struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
>   	return cma_obj;
>
>   error:
> -	drm->driver->gem_free_object(&cma_obj->base);
> +	drm_gem_object_unreference_unlocked(&cma_obj->base);
>   	return ERR_PTR(ret);
>   }
>   EXPORT_SYMBOL_GPL(drm_gem_cma_create);
> @@ -162,18 +162,12 @@ drm_gem_cma_create_with_handle(struct drm_file *file_priv,
>   	 * and handle has the id what user can see.
>   	 */
>   	ret = drm_gem_handle_create(file_priv, gem_obj, handle);
> -	if (ret)
> -		goto err_handle_create;
> -
>   	/* drop reference from allocate - handle holds it now. */
>   	drm_gem_object_unreference_unlocked(gem_obj);
> +	if (ret)
> +		return ERR_PTR(ret);
>
>   	return cma_obj;
> -
> -err_handle_create:
> -	drm->driver->gem_free_object(gem_obj);
> -
> -	return ERR_PTR(ret);
>   }
>
>   /**
>