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Groups > linux.kernel > #1702096 > unrolled thread
| Started by | Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com> |
|---|---|
| First post | 2017-08-02 15:10 +0200 |
| Last post | 2017-08-03 11:30 +0200 |
| Articles | 3 — 2 participants |
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Re: [Intel-gfx] [PATCH 3/4] lib/scatterlist: Introduce and export __sg_alloc_table_from_pages Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com> - 2017-08-02 15:10 +0200
Re: [Intel-gfx] [PATCH 3/4] lib/scatterlist: Introduce and export __sg_alloc_table_from_pages Andrew Morton <akpm@linux-foundation.org> - 2017-08-03 01:10 +0200
Re: [Intel-gfx] [PATCH 3/4] lib/scatterlist: Introduce and export __sg_alloc_table_from_pages Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com> - 2017-08-03 11:30 +0200
| From | Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com> |
|---|---|
| Date | 2017-08-02 15:10 +0200 |
| Subject | Re: [Intel-gfx] [PATCH 3/4] lib/scatterlist: Introduce and export __sg_alloc_table_from_pages |
| Message-ID | <ua1zs-1Rq-27@gated-at.bofh.it> |
Hi Andrew,
We have a couple of small lib/scatterlist.c tidies here, plus exporting
the new API which allows drivers to control the maximum coalesced entry
as created by __sg_alloc_table_from_pages.
I am looking for an ack to merge these three patches via the drm-intel tree.
Regards,
Tvrtko
On 27/07/2017 10:05, 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.
>
> v2: Reorder parameters. (Chris Wilson)
> v3: Fix incomplete reordering in v2.
> v4: max_segment needs to be page aligned.
> v5: Rebase.
> v6: Rebase.
>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
> Cc: linux-kernel@vger.kernel.org
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> (v2)
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> ---
> include/linux/scatterlist.h | 11 +++++----
> lib/scatterlist.c | 58 +++++++++++++++++++++++++++++++++++----------
> 2 files changed, 52 insertions(+), 17 deletions(-)
>
> diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
> index 6dd2ddbc6230..874b50c232de 100644
> --- a/include/linux/scatterlist.h
> +++ b/include/linux/scatterlist.h
> @@ -267,10 +267,13 @@ 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, unsigned int max_segment,
> + 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);
>
> size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
> size_t buflen, off_t skip, bool to_buffer);
> diff --git a/lib/scatterlist.c b/lib/scatterlist.c
> index 7b2e74da2c44..1a5900f9a057 100644
> --- a/lib/scatterlist.c
> +++ b/lib/scatterlist.c
> @@ -370,14 +370,15 @@ int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
> EXPORT_SYMBOL(sg_alloc_table);
>
> /**
> - * sg_alloc_table_from_pages - Allocate and initialize an sg table from
> - * an array of pages
> - * @sgt: The sg table header to use
> - * @pages: Pointer to an array of page pointers
> - * @n_pages: Number of pages in the pages array
> - * @offset: Offset from start of the first page to the start of a buffer
> - * @size: Number of valid bytes in the buffer (after offset)
> - * @gfp_mask: GFP allocation mask
> + * __sg_alloc_table_from_pages - Allocate and initialize an sg table from
> + * an array of pages
> + * @sgt: The sg table header to use
> + * @pages: Pointer to an array of page pointers
> + * @n_pages: Number of pages in the pages array
> + * @offset: Offset from start of the first page to the start of a buffer
> + * @size: Number of valid bytes in the buffer (after offset)
> + * @max_segment: Maximum size of a scatterlist node in bytes (page aligned)
> + * @gfp_mask: GFP allocation mask
> *
> * Description:
> * Allocate and initialize an sg table from a list of pages. Contiguous
> @@ -389,16 +390,18 @@ EXPORT_SYMBOL(sg_alloc_table);
> * Returns:
> * 0 on success, negative error on failure
> */
> -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, unsigned int max_segment,
> + gfp_t gfp_mask)
> {
> - const unsigned int max_segment = SCATTERLIST_MAX_SEGMENT;
> unsigned int chunks, cur_page, seg_len, i;
> int ret;
> struct scatterlist *s;
>
> + if (WARN_ON(!max_segment || offset_in_page(max_segment)))
> + return -EINVAL;
> +
> /* compute number of contiguous chunks */
> chunks = 1;
> seg_len = 0;
> @@ -440,6 +443,35 @@ int sg_alloc_table_from_pages(struct sg_table *sgt,
>
> return 0;
> }
> +EXPORT_SYMBOL(__sg_alloc_table_from_pages);
> +
> +/**
> + * sg_alloc_table_from_pages - Allocate and initialize an sg table from
> + * an array of pages
> + * @sgt: The sg table header to use
> + * @pages: Pointer to an array of page pointers
> + * @n_pages: Number of pages in the pages array
> + * @offset: Offset from start of the first page to the start of a buffer
> + * @size: Number of valid bytes in the buffer (after offset)
> + * @gfp_mask: GFP allocation mask
> + *
> + * Description:
> + * Allocate and initialize an sg table from a list of pages. Contiguous
> + * ranges of the pages are squashed into a single scatterlist node. A user
> + * may provide an offset at a start and a size of valid data in a buffer
> + * specified by the page array. The returned sg table is released by
> + * sg_free_table.
> + *
> + * Returns:
> + * 0 on success, negative error on failure
> + */
> +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)
> +{
> + return __sg_alloc_table_from_pages(sgt, pages, n_pages, offset, size,
> + SCATTERLIST_MAX_SEGMENT, gfp_mask);
> +}
> EXPORT_SYMBOL(sg_alloc_table_from_pages);
>
> void __sg_page_iter_start(struct sg_page_iter *piter,
>
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| From | Andrew Morton <akpm@linux-foundation.org> |
|---|---|
| Date | 2017-08-03 01:10 +0200 |
| Message-ID | <uaaW5-8aH-5@gated-at.bofh.it> |
| In reply to | #1702096 |
On Wed, 2 Aug 2017 14:06:39 +0100 Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com> wrote:
>
> Hi Andrew,
>
> We have a couple of small lib/scatterlist.c tidies here, plus exporting
> the new API which allows drivers to control the maximum coalesced entry
> as created by __sg_alloc_table_from_pages.
>
> I am looking for an ack to merge these three patches via the drm-intel tree.
>
>
> ...
>
> On 27/07/2017 10:05, 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-
"coalesced"
> > gather list.
> >
> > Introduce and export the __sg_alloc_table_from_pages function
> > which will allow it that control.
> >
>
> ...
>
> > --- a/lib/scatterlist.c
> > +++ b/lib/scatterlist.c
> > @@ -370,14 +370,15 @@ int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
> > EXPORT_SYMBOL(sg_alloc_table);
> >
> > /**
> > - * sg_alloc_table_from_pages - Allocate and initialize an sg table from
> > - * an array of pages
> > - * @sgt: The sg table header to use
> > - * @pages: Pointer to an array of page pointers
> > - * @n_pages: Number of pages in the pages array
> > - * @offset: Offset from start of the first page to the start of a buffer
> > - * @size: Number of valid bytes in the buffer (after offset)
> > - * @gfp_mask: GFP allocation mask
> > + * __sg_alloc_table_from_pages - Allocate and initialize an sg table from
> > + * an array of pages
> > + * @sgt: The sg table header to use
> > + * @pages: Pointer to an array of page pointers
> > + * @n_pages: Number of pages in the pages array
> > + * @offset: Offset from start of the first page to the start of a buffer
> > + * @size: Number of valid bytes in the buffer (after offset)
> > + * @max_segment: Maximum size of a scatterlist node in bytes (page aligned)
> > + * @gfp_mask: GFP allocation mask
> > *
> > * Description:
> > * Allocate and initialize an sg table from a list of pages. Contiguous
The Description doesn't describe how this differs from
sg_alloc_table_from_pages(), although it doesn't seem terribly
important.
> > +
> > +/**
> > + * sg_alloc_table_from_pages - Allocate and initialize an sg table from
> > + * an array of pages
> > + * @sgt: The sg table header to use
> > + * @pages: Pointer to an array of page pointers
> > + * @n_pages: Number of pages in the pages array
> > + * @offset: Offset from start of the first page to the start of a buffer
> > + * @size: Number of valid bytes in the buffer (after offset)
> > + * @gfp_mask: GFP allocation mask
> > + *
> > + * Description:
> > + * Allocate and initialize an sg table from a list of pages. Contiguous
> > + * ranges of the pages are squashed into a single scatterlist node. A user
> > + * may provide an offset at a start and a size of valid data in a buffer
> > + * specified by the page array. The returned sg table is released by
> > + * sg_free_table.
> > + *
> > + * Returns:
> > + * 0 on success, negative error on failure
> > + */
> > +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)
> > +{
> > + return __sg_alloc_table_from_pages(sgt, pages, n_pages, offset, size,
> > + SCATTERLIST_MAX_SEGMENT, gfp_mask);
> > +}
Making this an inline would save a bunch or stack space in the callers?
One could just add the new arg then run around and update the 10ish
callers but I guess the new interface is OK.
Otherwise it's OK by me, please go ahead as proposed.
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| From | Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com> |
|---|---|
| Date | 2017-08-03 11:30 +0200 |
| Message-ID | <uakC5-6qh-5@gated-at.bofh.it> |
| In reply to | #1702549 |
On 03/08/2017 00:01, Andrew Morton wrote:
> On Wed, 2 Aug 2017 14:06:39 +0100 Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com> wrote:
>
>>
>> Hi Andrew,
>>
>> We have a couple of small lib/scatterlist.c tidies here, plus exporting
>> the new API which allows drivers to control the maximum coalesced entry
>> as created by __sg_alloc_table_from_pages.
>>
>> I am looking for an ack to merge these three patches via the drm-intel tree.
>>
>>
>> ...
>>
>> On 27/07/2017 10:05, 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-
>
> "coalesced"
Oops, I've had this in other patches in the series. Fixed now.
>>> gather list.
>>>
>>> Introduce and export the __sg_alloc_table_from_pages function
>>> which will allow it that control.
>>>
>>
>> ...
>>
>>> --- a/lib/scatterlist.c
>>> +++ b/lib/scatterlist.c
>>> @@ -370,14 +370,15 @@ int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
>>> EXPORT_SYMBOL(sg_alloc_table);
>>>
>>> /**
>>> - * sg_alloc_table_from_pages - Allocate and initialize an sg table from
>>> - * an array of pages
>>> - * @sgt: The sg table header to use
>>> - * @pages: Pointer to an array of page pointers
>>> - * @n_pages: Number of pages in the pages array
>>> - * @offset: Offset from start of the first page to the start of a buffer
>>> - * @size: Number of valid bytes in the buffer (after offset)
>>> - * @gfp_mask: GFP allocation mask
>>> + * __sg_alloc_table_from_pages - Allocate and initialize an sg table from
>>> + * an array of pages
>>> + * @sgt: The sg table header to use
>>> + * @pages: Pointer to an array of page pointers
>>> + * @n_pages: Number of pages in the pages array
>>> + * @offset: Offset from start of the first page to the start of a buffer
>>> + * @size: Number of valid bytes in the buffer (after offset)
>>> + * @max_segment: Maximum size of a scatterlist node in bytes (page aligned)
>>> + * @gfp_mask: GFP allocation mask
>>> *
>>> * Description:
>>> * Allocate and initialize an sg table from a list of pages. Contiguous
>
> The Description doesn't describe how this differs from
> sg_alloc_table_from_pages(), although it doesn't seem terribly
> important.
Well spotted, I've fixed this as well.
>>> +
>>> +/**
>>> + * sg_alloc_table_from_pages - Allocate and initialize an sg table from
>>> + * an array of pages
>>> + * @sgt: The sg table header to use
>>> + * @pages: Pointer to an array of page pointers
>>> + * @n_pages: Number of pages in the pages array
>>> + * @offset: Offset from start of the first page to the start of a buffer
>>> + * @size: Number of valid bytes in the buffer (after offset)
>>> + * @gfp_mask: GFP allocation mask
>>> + *
>>> + * Description:
>>> + * Allocate and initialize an sg table from a list of pages. Contiguous
>>> + * ranges of the pages are squashed into a single scatterlist node. A user
>>> + * may provide an offset at a start and a size of valid data in a buffer
>>> + * specified by the page array. The returned sg table is released by
>>> + * sg_free_table.
>>> + *
>>> + * Returns:
>>> + * 0 on success, negative error on failure
>>> + */
>>> +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)
>>> +{
>>> + return __sg_alloc_table_from_pages(sgt, pages, n_pages, offset, size,
>>> + SCATTERLIST_MAX_SEGMENT, gfp_mask);
>>> +}
>
> Making this an inline would save a bunch or stack space in the callers?
>
> One could just add the new arg then run around and update the 10ish
> callers but I guess the new interface is OK.
On the first suggestion - there are other trivial wrappers in
lib/scatterlist.c which could benefit from the same treatment (move to
inline) so I opted not to do this in this patch but will send a follow up.
> Otherwise it's OK by me, please go ahead as proposed.
Thanks a lot!
Regards,
Tvrtko
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