On Tue, Jul 23, 2024 at 02:17:43PM +0200, Christian König wrote:
> Instead of a TTM reference grab a GEM reference whenever necessary.
> 
> Signed-off-by: Christian König <christian.koe...@amd.com>
> Cc: Alex Deucher <alexander.deuc...@amd.com>
> Cc: Felix Kuehling <felix.kuehl...@amd.com>
> Cc: amd-...@lists.freedesktop.org

I was worried that changing the refcounting for the mmu_interval_notifier
that this patch does could result in a use-after-free, but the mmu
notifier code already does the required amount of mmgrab/mmdrop, so we're
good.

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

Cheers, Sima

> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c    | 8 ++++----
>  drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 7 ++-----
>  2 files changed, 6 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c 
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> index 67c234bcf89f..6be3d7cd1c51 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> @@ -87,11 +87,11 @@ static const struct vm_operations_struct 
> amdgpu_gem_vm_ops = {
>  
>  static void amdgpu_gem_object_free(struct drm_gem_object *gobj)
>  {
> -     struct amdgpu_bo *robj = gem_to_amdgpu_bo(gobj);
> +     struct amdgpu_bo *aobj = gem_to_amdgpu_bo(gobj);
>  
> -     if (robj) {
> -             amdgpu_hmm_unregister(robj);
> -             amdgpu_bo_unref(&robj);
> +     if (aobj) {
> +             amdgpu_hmm_unregister(aobj);
> +             ttm_bo_put(&aobj->tbo);
>       }
>  }
>  
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c 
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> index 8d8c39be6129..6c187e310034 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> @@ -853,7 +853,7 @@ struct amdgpu_bo *amdgpu_bo_ref(struct amdgpu_bo *bo)
>       if (bo == NULL)
>               return NULL;
>  
> -     ttm_bo_get(&bo->tbo);
> +     drm_gem_object_get(&bo->tbo.base);
>       return bo;
>  }
>  
> @@ -865,13 +865,10 @@ struct amdgpu_bo *amdgpu_bo_ref(struct amdgpu_bo *bo)
>   */
>  void amdgpu_bo_unref(struct amdgpu_bo **bo)
>  {
> -     struct ttm_buffer_object *tbo;
> -
>       if ((*bo) == NULL)
>               return;
>  
> -     tbo = &((*bo)->tbo);
> -     ttm_bo_put(tbo);
> +     drm_gem_object_get(&(*bo)->tbo.base);
>       *bo = NULL;
>  }
>  
> -- 
> 2.34.1
> 

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

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