Re: [PATCH v3] drm/gem: Internally test import_attach for imported objects

[Simona Vetter <simona.vetter@ffwll.ch>]

On Wed, Apr 16, 2025 at 08:57:45AM +0200, Thomas Zimmermann wrote:
> Test struct drm_gem_object.import_attach to detect imported objects.
> 
> During object clenanup, the dma_buf field might be NULL. Testing it in
> an object's free callback then incorrectly does a cleanup as for native
> objects. Happens for calls to drm_mode_destroy_dumb_ioctl() that
> clears the dma_buf field in drm_gem_object_exported_dma_buf_free().
> 
> v3:
> - only test for import_attach (Boris)
> v2:
> - use import_attach.dmabuf instead of dma_buf (Christian)
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Fixes: b57aa47d39e9 ("drm/gem: Test for imported GEM buffers with helper")
> Reported-by: Andy Yan <andyshrk@163.com>
> Closes: https://lore.kernel.org/dri-devel/38d09d34.4354.196379aa560.Coremail.andyshrk@163.com/
> Tested-by: Andy Yan <andyshrk@163.com>
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: Anusha Srivatsa <asrivats@redhat.com>
> Cc: Christian König <christian.koenig@amd.com>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Maxime Ripard <mripard@kernel.org>
> Cc: David Airlie <airlied@gmail.com>
> Cc: Simona Vetter <simona@ffwll.ch>
> Cc: Sumit Semwal <sumit.semwal@linaro.org>
> Cc: "Christian König" <christian.koenig@amd.com>
> Cc: dri-devel@lists.freedesktop.org
> Cc: linux-media@vger.kernel.org
> Cc: linaro-mm-sig@lists.linaro.org

Reviewed-by: Simona Vetter <simona.vetter@ffwll.ch>

> ---
>  include/drm/drm_gem.h | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
> index 9b71f7a9f3f8..a3133a08267c 100644
> --- a/include/drm/drm_gem.h
> +++ b/include/drm/drm_gem.h
> @@ -588,8 +588,7 @@ static inline bool drm_gem_object_is_shared_for_memory_stats(struct drm_gem_obje
>   */
>  static inline bool drm_gem_is_imported(const struct drm_gem_object *obj)
>  {
> -	/* The dma-buf's priv field points to the original GEM object. */
> -	return obj->dma_buf && (obj->dma_buf->priv != obj);
> +	return !!obj->import_attach;
>  }
>  
>  #ifdef CONFIG_LOCKDEP
> -- 
> 2.49.0
> 

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