Re: [PATCH v2 4/6] rangeset: introduce rangeset_subtract

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Thu, 8 May 2025, Stewart Hildebrand wrote:
> Introduce rangeset_subtract() to remove regions in r2 from r1.
> 
> Signed-off-by: Stewart Hildebrand <stewart.hildebrand@xxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>

> ---
> v1->v2:
> * no change
> ---
>  xen/common/rangeset.c      | 12 ++++++++++++
>  xen/include/xen/rangeset.h |  3 +++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/xen/common/rangeset.c b/xen/common/rangeset.c
> index e75871039087..b9e8912fb1c3 100644
> --- a/xen/common/rangeset.c
> +++ b/xen/common/rangeset.c
> @@ -397,6 +397,18 @@ int rangeset_merge(struct rangeset *r1, struct rangeset 
> *r2)
>      return rangeset_report_ranges(r2, 0, ~0UL, merge, r1);
>  }
>  
> +static int cf_check subtract(unsigned long s, unsigned long e, void *data)
> +{
> +    struct rangeset *r = data;
> +
> +    return rangeset_remove_range(r, s, e);
> +}
> +
> +int rangeset_subtract(struct rangeset *r1, struct rangeset *r2)
> +{
> +    return rangeset_report_ranges(r2, 0, ~0UL, subtract, r1);
> +}
> +
>  int rangeset_add_singleton(
>      struct rangeset *r, unsigned long s)
>  {
> diff --git a/xen/include/xen/rangeset.h b/xen/include/xen/rangeset.h
> index 96c918082501..817505badf6f 100644
> --- a/xen/include/xen/rangeset.h
> +++ b/xen/include/xen/rangeset.h
> @@ -85,6 +85,9 @@ int rangeset_consume_ranges(struct rangeset *r,
>  /* Merge rangeset r2 into rangeset r1. */
>  int __must_check rangeset_merge(struct rangeset *r1, struct rangeset *r2);
>  
> +/* Subtract rangeset r2 from rangeset r1. */
> +int __must_check rangeset_subtract(struct rangeset *r1, struct rangeset *r2);
> +
>  /* Add/remove/query a single number. */
>  int __must_check rangeset_add_singleton(
>      struct rangeset *r, unsigned long s);
> -- 
> 2.49.0
>