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

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, May 31, 2016 at 10:25:52PM +0100, 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@collabora.com>
> Fixes: 9f0ba539d13ae (drm/gem: support BO freeing without dev->struct_mutex)
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Robert Foss <robert.foss@collabora.com>
> Cc: Daniel Vetter <daniel.vetter@intel.com>
> Cc: Eric Anholt <eric@anholt.net>
> Cc: Alex Deucher <alexdeucher@gmail.com>
> Cc: Lucas Stach <l.stach@pengutronix.de>
> Cc: stable@vger.kernel.org

The original offending commit is only in 4.7, so no need for cc: stable.
It won't hurt either though.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> ---
>  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);
>  }
>  
>  /**
> -- 
> 2.8.1
> 
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> Intel-gfx@lists.freedesktop.org
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch