Re: [PATCH 1/2] drm: call drm_gem_object_funcs.mmap with fake offset

[Daniel Vetter]

On Thu, Nov 21, 2019 at 11:38:06AM +0100, Gerd Hoffmann wrote:
> The fake offset is going to stay, so change the calling convention for
> drm_gem_object_funcs.mmap to include the fake offset.  Update all users
> accordingly.

Please add to the commit message:

Note that this reverts 83b8a6f242ea ("drm/gem: Fix mmap fake offset
handling for drm_gem_object_funcs.mmap") and on top then adds the fake
offset to  drm_gem_prime_mmap to make sure all paths leading to
obj->funcs->mmap are consistent.

Fixes: 83b8a6f242ea ("drm/gem: Fix mmap fake offset handling for drm_gem_object_funcs.mmap")
Cc: Gerd Hoffmann <kraxel@xxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Rob Herring <robh@xxxxxxxxxx>

With that also Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
-Daniel
> 
> Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
> ---
>  include/drm/drm_gem.h                  | 4 +---
>  drivers/gpu/drm/drm_gem.c              | 3 ---
>  drivers/gpu/drm/drm_gem_shmem_helper.c | 3 +++
>  drivers/gpu/drm/drm_prime.c            | 3 +++
>  drivers/gpu/drm/ttm/ttm_bo_vm.c        | 7 -------
>  5 files changed, 7 insertions(+), 13 deletions(-)
> 
> diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
> index 97a48165642c..0b375069cd48 100644
> --- a/include/drm/drm_gem.h
> +++ b/include/drm/drm_gem.h
> @@ -159,9 +159,7 @@ struct drm_gem_object_funcs {
>  	 *
>  	 * The callback is used by by both drm_gem_mmap_obj() and
>  	 * drm_gem_prime_mmap().  When @mmap is present @vm_ops is not
> -	 * used, the @mmap callback must set vma->vm_ops instead. The @mmap
> -	 * callback is always called with a 0 offset. The caller will remove
> -	 * the fake offset as necessary.
> +	 * used, the @mmap callback must set vma->vm_ops instead.
>  	 */
>  	int (*mmap)(struct drm_gem_object *obj, struct vm_area_struct *vma);
>  
> diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
> index 2f2b889096b0..56f42e0f2584 100644
> --- a/drivers/gpu/drm/drm_gem.c
> +++ b/drivers/gpu/drm/drm_gem.c
> @@ -1106,9 +1106,6 @@ int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size,
>  		return -EINVAL;
>  
>  	if (obj->funcs && obj->funcs->mmap) {
> -		/* Remove the fake offset */
> -		vma->vm_pgoff -= drm_vma_node_start(&obj->vma_node);
> -
>  		ret = obj->funcs->mmap(obj, vma);
>  		if (ret)
>  			return ret;
> diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
> index 0810d3ef6961..a421a2eed48a 100644
> --- a/drivers/gpu/drm/drm_gem_shmem_helper.c
> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
> @@ -528,6 +528,9 @@ int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
>  	struct drm_gem_shmem_object *shmem;
>  	int ret;
>  
> +	/* Remove the fake offset */
> +	vma->vm_pgoff -= drm_vma_node_start(&obj->vma_node);
> +
>  	shmem = to_drm_gem_shmem_obj(obj);
>  
>  	ret = drm_gem_shmem_get_pages(shmem);
> diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
> index 0814211b0f3f..a9633bd241bb 100644
> --- a/drivers/gpu/drm/drm_prime.c
> +++ b/drivers/gpu/drm/drm_prime.c
> @@ -714,6 +714,9 @@ int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
>  	int ret;
>  
>  	if (obj->funcs && obj->funcs->mmap) {
> +		/* Add the fake offset */
> +		vma->vm_pgoff += drm_vma_node_start(&obj->vma_node);
> +
>  		ret = obj->funcs->mmap(obj, vma);
>  		if (ret)
>  			return ret;
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> index e6495ca2630b..3e8c3de91ae4 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> @@ -514,13 +514,6 @@ EXPORT_SYMBOL(ttm_bo_mmap);
>  int ttm_bo_mmap_obj(struct vm_area_struct *vma, struct ttm_buffer_object *bo)
>  {
>  	ttm_bo_get(bo);
> -
> -	/*
> -	 * FIXME: &drm_gem_object_funcs.mmap is called with the fake offset
> -	 * removed. Add it back here until the rest of TTM works without it.
> -	 */
> -	vma->vm_pgoff += drm_vma_node_start(&bo->base.vma_node);
> -
>  	ttm_bo_mmap_vma_setup(bo, vma);
>  	return 0;
>  }
> -- 
> 2.18.1
> 

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