Re: [PATCH] drm/amdgpu: Initialise drm_gem_object_funcs for imported BOs

[Christian König <ckoenig.leichtzumerken@xxxxxxxxx>]

Am 08.12.20 um 18:10 schrieb Andrey Grodzovsky:
> For BOs imported from outside of amdgpu, setting of amdgpu_gem_object_funcs
> was missing in amdgpu_dma_buf_create_obj. Fix by refactoring BO creation
> and amdgpu_gem_object_funcs setting into single function called
> from both code paths.

Can you outline why we can't use amdgpu_gem_object_create() directly?

I mean we have a bit of extra error handling in there and we need to 
grab the resv lock and set the domains after creation, but that 
shouldn't matter and I don't see why that should not work.

Thanks,
Christian.

> This fixes null ptr regression casued by commit
> d693def drm: Remove obsolete GEM and PRIME callbacks from struct drm_driver
>
> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@xxxxxxx>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c | 13 ++++++-------
>   drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c     | 22 +++++++++++++++++-----
>   drivers/gpu/drm/amd/amdgpu/amdgpu_gem.h     |  5 +++++
>   3 files changed, 28 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
> index e5919ef..da4d0ab 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
> @@ -405,6 +405,7 @@ struct dma_buf *amdgpu_gem_prime_export(struct drm_gem_object *gobj,
>   	return buf;
>   }
>   
> +
>   /**
>    * amdgpu_dma_buf_create_obj - create BO for DMA-buf import
>    *
> @@ -424,7 +425,7 @@ amdgpu_dma_buf_create_obj(struct drm_device *dev, struct dma_buf *dma_buf)
>   	struct amdgpu_device *adev = drm_to_adev(dev);
>   	struct amdgpu_bo *bo;
>   	struct amdgpu_bo_param bp;
> -	int ret;
> +	struct drm_gem_object *obj;
>   
>   	memset(&bp, 0, sizeof(bp));
>   	bp.size = dma_buf->size;
> @@ -434,21 +435,19 @@ amdgpu_dma_buf_create_obj(struct drm_device *dev, struct dma_buf *dma_buf)
>   	bp.type = ttm_bo_type_sg;
>   	bp.resv = resv;
>   	dma_resv_lock(resv, NULL);
> -	ret = amdgpu_bo_create(adev, &bp, &bo);
> -	if (ret)
> +	obj = amdgpu_gem_object_create_raw(adev, &bp);
> +	if (IS_ERR(obj))
>   		goto error;
>   
> +	bo = gem_to_amdgpu_bo(obj);
>   	bo->allowed_domains = AMDGPU_GEM_DOMAIN_GTT;
>   	bo->preferred_domains = AMDGPU_GEM_DOMAIN_GTT;
>   	if (dma_buf->ops != &amdgpu_dmabuf_ops)
>   		bo->prime_shared_count = 1;
>   
> -	dma_resv_unlock(resv);
> -	return &bo->tbo.base;
> -
>   error:
>   	dma_resv_unlock(resv);
> -	return ERR_PTR(ret);
> +	return obj;
>   }
>   
>   /**
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> index c9f94fb..5f22ce6 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> @@ -52,13 +52,26 @@ static void amdgpu_gem_object_free(struct drm_gem_object *gobj)
>   	}
>   }
>   
> +struct drm_gem_object *amdgpu_gem_object_create_raw(struct amdgpu_device *adev,
> +						    struct amdgpu_bo_param *bp)
> +{
> +	struct amdgpu_bo *bo;
> +	int r;
> +
> +	r = amdgpu_bo_create(adev, bp, &bo);
> +	if (r)
> +		return ERR_PTR(r);
> +
> +	bo->tbo.base.funcs = &amdgpu_gem_object_funcs;
> +	return &bo->tbo.base;
> +}
> +
>   int amdgpu_gem_object_create(struct amdgpu_device *adev, unsigned long size,
>   			     int alignment, u32 initial_domain,
>   			     u64 flags, enum ttm_bo_type type,
>   			     struct dma_resv *resv,
>   			     struct drm_gem_object **obj)
>   {
> -	struct amdgpu_bo *bo;
>   	struct amdgpu_bo_param bp;
>   	int r;
>   
> @@ -73,8 +86,9 @@ int amdgpu_gem_object_create(struct amdgpu_device *adev, unsigned long size,
>   retry:
>   	bp.flags = flags;
>   	bp.domain = initial_domain;
> -	r = amdgpu_bo_create(adev, &bp, &bo);
> -	if (r) {
> +	*obj = amdgpu_gem_object_create_raw(adev, &bp);
> +	if (IS_ERR(*obj)) {
> +		r = PTR_ERR(*obj);
>   		if (r != -ERESTARTSYS) {
>   			if (flags & AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED) {
>   				flags &= ~AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED;
> @@ -90,8 +104,6 @@ int amdgpu_gem_object_create(struct amdgpu_device *adev, unsigned long size,
>   		}
>   		return r;
>   	}
> -	*obj = &bo->tbo.base;
> -	(*obj)->funcs = &amdgpu_gem_object_funcs;
>   
>   	return 0;
>   }
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.h
> index 637bf51..a6b90d3 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.h
> @@ -38,12 +38,17 @@ unsigned long amdgpu_gem_timeout(uint64_t timeout_ns);
>   /*
>    * GEM objects.
>    */
> +
> +struct amdgpu_bo_param;
> +
>   void amdgpu_gem_force_release(struct amdgpu_device *adev);
>   int amdgpu_gem_object_create(struct amdgpu_device *adev, unsigned long size,
>   			     int alignment, u32 initial_domain,
>   			     u64 flags, enum ttm_bo_type type,
>   			     struct dma_resv *resv,
>   			     struct drm_gem_object **obj);
> +struct drm_gem_object *amdgpu_gem_object_create_raw(struct amdgpu_device *adev,
> +						    struct amdgpu_bo_param *bp);
>   
>   int amdgpu_mode_dumb_create(struct drm_file *file_priv,
>   			    struct drm_device *dev,

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