Re: [PATCH v3 5/7] drm/vmwgfx: Inline ttm_bo_mmap() into vmwgfx driver

["Christian König" <ckoenig.leichtzumerken@gmail.com>]

Am 16.04.21 um 15:31 schrieb Thomas Zimmermann:
> The vmwgfx driver is the only remaining user of ttm_bo_mmap(). Inline
> the code. The internal helper ttm_bo_vm_lookup() is now also part of
> vmwgfx as vmw_bo_vm_lookup().
>
> v2:
> 	* replace pr_err() with drm_err() (Zack)
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Reviewed-by: Zack Rusin <zackr@vmware.com>
> ---
>   drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c | 56 ++++++++++++++++++++++--
>   1 file changed, 53 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
> index cb9975889e2f..c8b6543b4e39 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
> @@ -27,6 +27,32 @@
>   
>   #include "vmwgfx_drv.h"
>   
> +static struct ttm_buffer_object *vmw_bo_vm_lookup(struct ttm_device *bdev,
> +						  unsigned long offset,
> +						  unsigned long pages)
> +{
> +	struct vmw_private *dev_priv = container_of(bdev, struct vmw_private, bdev);
> +	struct drm_device *drm = &dev_priv->drm;
> +	struct drm_vma_offset_node *node;
> +	struct ttm_buffer_object *bo = NULL;
> +
> +	drm_vma_offset_lock_lookup(bdev->vma_manager);
> +
> +	node = drm_vma_offset_lookup_locked(bdev->vma_manager, offset, pages);
> +	if (likely(node)) {
> +		bo = container_of(node, struct ttm_buffer_object,
> +				  base.vma_node);
> +		bo = ttm_bo_get_unless_zero(bo);
> +	}
> +
> +	drm_vma_offset_unlock_lookup(bdev->vma_manager);
> +
> +	if (!bo)
> +		drm_err(drm, "Could not find buffer object to map\n");
> +
> +	return bo;
> +}
> +
>   int vmw_mmap(struct file *filp, struct vm_area_struct *vma)
>   {
>   	static const struct vm_operations_struct vmw_vm_ops = {
> @@ -41,10 +67,28 @@ int vmw_mmap(struct file *filp, struct vm_area_struct *vma)
>   	};
>   	struct drm_file *file_priv = filp->private_data;
>   	struct vmw_private *dev_priv = vmw_priv(file_priv->minor->dev);
> -	int ret = ttm_bo_mmap(filp, vma, &dev_priv->bdev);
> +	struct ttm_device *bdev = &dev_priv->bdev;
> +	struct ttm_buffer_object *bo;
> +	int ret;
> +
> +	if (unlikely(vma->vm_pgoff < DRM_FILE_PAGE_OFFSET_START))
> +		return -EINVAL;
> +
> +	bo = vmw_bo_vm_lookup(bdev, vma->vm_pgoff, vma_pages(vma));
> +	if (unlikely(!bo))
> +		return -EINVAL;
>   
> -	if (ret)
> -		return ret;
> +	if (unlikely(!bo->bdev->funcs->verify_access)) {
> +		ret = -EPERM;
> +		goto out_unref;
> +	}
> +	ret = bo->bdev->funcs->verify_access(bo, filp);

Is there any reason we can't call vmw_verify_access() directly here?

Would allow us to completely nuke the verify_access callback as well as 
far as I can see.

Regards,
Christian.

> +	if (unlikely(ret != 0))
> +		goto out_unref;
> +
> +	ret = ttm_bo_mmap_obj(vma, bo);
> +	if (unlikely(ret != 0))
> +		goto out_unref;
>   
>   	vma->vm_ops = &vmw_vm_ops;
>   
> @@ -52,7 +96,13 @@ int vmw_mmap(struct file *filp, struct vm_area_struct *vma)
>   	if (!is_cow_mapping(vma->vm_flags))
>   		vma->vm_flags = (vma->vm_flags & ~VM_MIXEDMAP) | VM_PFNMAP;
>   
> +	ttm_bo_put(bo); /* release extra ref taken by ttm_bo_mmap_obj() */
> +
>   	return 0;
> +
> +out_unref:
> +	ttm_bo_put(bo);
> +	return ret;
>   }
>   
>   /* struct vmw_validation_mem callback */

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