Re: [Intel-gfx] [PATCH 3/4] lib/scatterlist: Introduce and export __sg_alloc_table_from_pages

Chris Wilson
2016-11-11T10:24:36Z

On Fri, Nov 11, 2016 at 08:50:19AM +0000, Tvrtko Ursulin wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>
> Drivers like i915 benefit from being able to control the maxium
> size of the sg coallesced segment while building the scatter-
> gather list.
>
> Introduce and export the __sg_alloc_table_from_pages function
> which will allow it that control.
>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
> Cc: linux-kernel@vger.kernel.org

> ---
> include/linux/scatterlist.h | 11 +++++----
> lib/scatterlist.c | 55 ++++++++++++++++++++++++++++++++++-----------
> 2 files changed, 49 insertions(+), 17 deletions(-)
>
> diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
> index c981bee1a3ae..29591dbb20fd 100644
> --- a/include/linux/scatterlist.h
> +++ b/include/linux/scatterlist.h
> @@ -261,10 +261,13 @@ void sg_free_table(struct sg_table *);
> int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int,
> struct scatterlist *, gfp_t, sg_alloc_fn *);
> int sg_alloc_table(struct sg_table *, unsigned int, gfp_t);
> -int sg_alloc_table_from_pages(struct sg_table *sgt,
> - struct page **pages, unsigned int n_pages,
> - unsigned int offset, unsigned long size,
> - gfp_t gfp_mask);
> +int __sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages,
> + unsigned int n_pages, unsigned int offset,
> + unsigned long size, gfp_t gfp_mask,
> + unsigned int max_segment);

Just the question of parameter order, I like gfp_t last :)
And I think offset / size / max_segment tie together.
-Chris

--
Chris Wilson, Intel Open Source Technology Centre