Re: [PATCH v13 10/15] vfio/type1: Implement recursive vfio_find_dma_from_node

[Alex Williamson <alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On Thu,  6 Oct 2016 08:45:26 +0000
Eric Auger <eric.auger-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:

> This patch handles the case where a node is encountered, matching
> @start and @size arguments but not matching the @type argument.
> In that case, we need to skip that node and pursue the search in the
> node's leaves. In case @start is inferior to the node's base, we
> resume the search on the left leaf. If the recursive search on the left
> leaves did not produce any match, we search the right leaves recursively.
> 
> Signed-off-by: Eric Auger <eric.auger-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

Acked-by: Alex Williamson <alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
 
> ---
> 
> v10: creation
> ---
>  drivers/vfio/vfio_iommu_type1.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index cb7267a..65a4038 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -125,7 +125,17 @@ static struct vfio_dma *vfio_find_dma_from_node(struct rb_node *top,
>  	if (type == VFIO_IOVA_ANY || dma->type == type)
>  		return dma;
>  
> -	return NULL;
> +	/* restart 2 searches skipping the current node */
> +	if (start < dma->iova) {
> +		dma = vfio_find_dma_from_node(node->rb_left, start,
> +					      size, type);
> +		if (dma)
> +			return dma;
> +	}
> +	if (start + size > dma->iova + dma->size)
> +		dma = vfio_find_dma_from_node(node->rb_right, start,
> +					      size, type);
> +	return dma;
>  }
>  
>  /**