Replace the current hand-crafted code for extracting pages and DMA
addresses from the given scatterlist by the much more robust
code based on the generic scatterlist iterators and recently
introduced sg_table-based wrappers. The resulting code is simple and
easy to understand, so the comment describing the old code is no
longer needed.
Signed-off-by: Marek Szyprowski <[email protected]>
---
For more information, see '[PATCH v5 00/38] DRM: fix struct sg_table nents
vs. orig_nents misuse' thread:
https://lore.kernel.org/linux-iommu/[email protected]/T/
---
drivers/gpu/drm/drm_prime.c | 47 ++++++++++++++-------------------------------
1 file changed, 14 insertions(+), 33 deletions(-)
diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index 1d2e5fe..dfdf4d4 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -985,45 +985,26 @@ struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,
dma_addr_t *addrs, int max_entries)
{
- unsigned count;
- struct scatterlist *sg;
- struct page *page;
- u32 page_len, page_index;
- dma_addr_t addr;
- u32 dma_len, dma_index;
+ struct sg_dma_page_iter dma_iter;
+ struct sg_page_iter page_iter;
+ struct page **p = pages;
+ dma_addr_t *a = addrs;
- /*
- * Scatterlist elements contains both pages and DMA addresses, but
- * one shoud not assume 1:1 relation between them. The sg->length is
- * the size of the physical memory chunk described by the sg->page,
- * while sg_dma_len(sg) is the size of the DMA (IO virtual) chunk
- * described by the sg_dma_address(sg).
- */
- page_index = 0;
- dma_index = 0;
- for_each_sg(sgt->sgl, sg, sgt->nents, count) {
- page_len = sg->length;
- page = sg_page(sg);
- dma_len = sg_dma_len(sg);
- addr = sg_dma_address(sg);
-
- while (pages && page_len > 0) {
- if (WARN_ON(page_index >= max_entries))
+ if (pages) {
+ for_each_sgtable_page(sgt, &page_iter, 0) {
+ if (p - pages >= max_entries)
return -1;
- pages[page_index] = page;
- page++;
- page_len -= PAGE_SIZE;
- page_index++;
+ *p++ = sg_page_iter_page(&page_iter);
}
- while (addrs && dma_len > 0) {
- if (WARN_ON(dma_index >= max_entries))
+ }
+ if (addrs) {
+ for_each_sgtable_dma_page(sgt, &dma_iter, 0) {
+ if (a - addrs >= max_entries)
return -1;
- addrs[dma_index] = addr;
- addr += PAGE_SIZE;
- dma_len -= PAGE_SIZE;
- dma_index++;
+ *a++ = sg_page_iter_dma_address(&dma_iter);
}
}
+
return 0;
}
EXPORT_SYMBOL(drm_prime_sg_to_page_addr_arrays);
--
1.9.1
Tested-by: Alex Goins <[email protected]>
This change fixes a regression with drm_prime_sg_to_page_addr_arrays() and
AMDGPU in v5.9.
Commit 39913934 similarly revamped AMDGPU to use sgtable helper functions. When
it changed from dma_map_sg_attrs() to dma_map_sgtable(), as a side effect it
started correctly updating sgt->nents to the return value of dma_map_sg_attrs().
However, drm_prime_sg_to_page_addr_arrays() incorrectly uses sgt->nents to
iterate over pages, rather than sgt->orig_nents, resulting in it now returning
the incorrect number of pages on AMDGPU.
I had written a patch that changes drm_prime_sg_to_page_addr_arrays() to use
for_each_sgtable_sg() instead of for_each_sg(), iterating using sgt->orig_nents:
- for_each_sg(sgt->sgl, sg, sgt->nents, count) {
+ for_each_sgtable_sg(sgt, sg, count) {
This patch takes it further, but still has the effect of fixing the number of
pages that drm_prime_sg_to_page_addr_arrays() returns. Something like this
should be included in v5.9 to prevent a regression with AMDGPU.
Thanks,
Alex
On Wed, 13 May 2020, Marek Szyprowski wrote:
> Replace the current hand-crafted code for extracting pages and DMA
> addresses from the given scatterlist by the much more robust
> code based on the generic scatterlist iterators and recently
> introduced sg_table-based wrappers. The resulting code is simple and
> easy to understand, so the comment describing the old code is no
> longer needed.
>
> Signed-off-by: Marek Szyprowski <[email protected]>
> ---
> For more information, see '[PATCH v5 00/38] DRM: fix struct sg_table nents
> vs. orig_nents misuse' thread:
> https://lore.kernel.org/linux-iommu/[email protected]/T/
> ---
> drivers/gpu/drm/drm_prime.c | 47 ++++++++++++++-------------------------------
> 1 file changed, 14 insertions(+), 33 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
> index 1d2e5fe..dfdf4d4 100644
> --- a/drivers/gpu/drm/drm_prime.c
> +++ b/drivers/gpu/drm/drm_prime.c
> @@ -985,45 +985,26 @@ struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
> int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,
> dma_addr_t *addrs, int max_entries)
> {
> - unsigned count;
> - struct scatterlist *sg;
> - struct page *page;
> - u32 page_len, page_index;
> - dma_addr_t addr;
> - u32 dma_len, dma_index;
> + struct sg_dma_page_iter dma_iter;
> + struct sg_page_iter page_iter;
> + struct page **p = pages;
> + dma_addr_t *a = addrs;
>
> - /*
> - * Scatterlist elements contains both pages and DMA addresses, but
> - * one shoud not assume 1:1 relation between them. The sg->length is
> - * the size of the physical memory chunk described by the sg->page,
> - * while sg_dma_len(sg) is the size of the DMA (IO virtual) chunk
> - * described by the sg_dma_address(sg).
> - */
> - page_index = 0;
> - dma_index = 0;
> - for_each_sg(sgt->sgl, sg, sgt->nents, count) {
> - page_len = sg->length;
> - page = sg_page(sg);
> - dma_len = sg_dma_len(sg);
> - addr = sg_dma_address(sg);
> -
> - while (pages && page_len > 0) {
> - if (WARN_ON(page_index >= max_entries))
> + if (pages) {
> + for_each_sgtable_page(sgt, &page_iter, 0) {
> + if (p - pages >= max_entries)
> return -1;
> - pages[page_index] = page;
> - page++;
> - page_len -= PAGE_SIZE;
> - page_index++;
> + *p++ = sg_page_iter_page(&page_iter);
> }
> - while (addrs && dma_len > 0) {
> - if (WARN_ON(dma_index >= max_entries))
> + }
> + if (addrs) {
> + for_each_sgtable_dma_page(sgt, &dma_iter, 0) {
> + if (a - addrs >= max_entries)
> return -1;
> - addrs[dma_index] = addr;
> - addr += PAGE_SIZE;
> - dma_len -= PAGE_SIZE;
> - dma_index++;
> + *a++ = sg_page_iter_dma_address(&dma_iter);
> }
> }
> +
> return 0;
> }
> EXPORT_SYMBOL(drm_prime_sg_to_page_addr_arrays);
> --
> 1.9.1
>
> _______________________________________________
> dri-devel mailing list
> [email protected]
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>
Hi Alex,
On 22.09.2020 01:15, Alex Goins wrote:
> Tested-by: Alex Goins <[email protected]>
>
> This change fixes a regression with drm_prime_sg_to_page_addr_arrays() and
> AMDGPU in v5.9.
Thanks for testing!
> Commit 39913934 similarly revamped AMDGPU to use sgtable helper functions. When
> it changed from dma_map_sg_attrs() to dma_map_sgtable(), as a side effect it
> started correctly updating sgt->nents to the return value of dma_map_sg_attrs().
> However, drm_prime_sg_to_page_addr_arrays() incorrectly uses sgt->nents to
> iterate over pages, rather than sgt->orig_nents, resulting in it now returning
> the incorrect number of pages on AMDGPU.
>
> I had written a patch that changes drm_prime_sg_to_page_addr_arrays() to use
> for_each_sgtable_sg() instead of for_each_sg(), iterating using sgt->orig_nents:
>
> - for_each_sg(sgt->sgl, sg, sgt->nents, count) {
> + for_each_sgtable_sg(sgt, sg, count) {
>
> This patch takes it further, but still has the effect of fixing the number of
> pages that drm_prime_sg_to_page_addr_arrays() returns. Something like this
> should be included in v5.9 to prevent a regression with AMDGPU.
Probably the easiest way to handle a fix for v5.9 would be to simply
merge the latest version of this patch also to v5.9-rcX:
https://lore.kernel.org/dri-devel/[email protected]/
This way we would get it fixed and avoid possible conflict in the -next.
Do you have any AMDGPU fixes for v5.9 in the queue? Maybe you can add
that patch to the queue? Dave: would it be okay that way?
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
Hi Marek,
On Tue, 22 Sep 2020, Marek Szyprowski wrote:
> External email: Use caution opening links or attachments
>
>
> Hi Alex,
>
> On 22.09.2020 01:15, Alex Goins wrote:
> > Tested-by: Alex Goins <[email protected]>
> >
> > This change fixes a regression with drm_prime_sg_to_page_addr_arrays() and
> > AMDGPU in v5.9.
>
> Thanks for testing!
>
> > Commit 39913934 similarly revamped AMDGPU to use sgtable helper functions. When
> > it changed from dma_map_sg_attrs() to dma_map_sgtable(), as a side effect it
> > started correctly updating sgt->nents to the return value of dma_map_sg_attrs().
> > However, drm_prime_sg_to_page_addr_arrays() incorrectly uses sgt->nents to
> > iterate over pages, rather than sgt->orig_nents, resulting in it now returning
> > the incorrect number of pages on AMDGPU.
> >
> > I had written a patch that changes drm_prime_sg_to_page_addr_arrays() to use
> > for_each_sgtable_sg() instead of for_each_sg(), iterating using sgt->orig_nents:
> >
> > - for_each_sg(sgt->sgl, sg, sgt->nents, count) {
> > + for_each_sgtable_sg(sgt, sg, count) {
> >
> > This patch takes it further, but still has the effect of fixing the number of
> > pages that drm_prime_sg_to_page_addr_arrays() returns. Something like this
> > should be included in v5.9 to prevent a regression with AMDGPU.
>
> Probably the easiest way to handle a fix for v5.9 would be to simply
> merge the latest version of this patch also to v5.9-rcX:
> https://lore.kernel.org/dri-devel/[email protected]/
Tested-by: Alex Goins <[email protected]> that version too.
>
> This way we would get it fixed and avoid possible conflict in the -next.
> Do you have any AMDGPU fixes for v5.9 in the queue? Maybe you can add that
> patch to the queue?
I don't have any more AMDGPU fixes, just want to ensure that this makes it in.
Thanks,
Alex
> Dave: would it be okay that way?
>
> Best regards
> --
> Marek Szyprowski, PhD
> Samsung R&D Institute Poland
>
>
On Tue, Sep 22, 2020 at 2:28 AM Marek Szyprowski
<[email protected]> wrote:
>
> Hi Alex,
>
> On 22.09.2020 01:15, Alex Goins wrote:
> > Tested-by: Alex Goins <[email protected]>
> >
> > This change fixes a regression with drm_prime_sg_to_page_addr_arrays() and
> > AMDGPU in v5.9.
>
> Thanks for testing!
>
> > Commit 39913934 similarly revamped AMDGPU to use sgtable helper functions. When
> > it changed from dma_map_sg_attrs() to dma_map_sgtable(), as a side effect it
> > started correctly updating sgt->nents to the return value of dma_map_sg_attrs().
> > However, drm_prime_sg_to_page_addr_arrays() incorrectly uses sgt->nents to
> > iterate over pages, rather than sgt->orig_nents, resulting in it now returning
> > the incorrect number of pages on AMDGPU.
> >
> > I had written a patch that changes drm_prime_sg_to_page_addr_arrays() to use
> > for_each_sgtable_sg() instead of for_each_sg(), iterating using sgt->orig_nents:
> >
> > - for_each_sg(sgt->sgl, sg, sgt->nents, count) {
> > + for_each_sgtable_sg(sgt, sg, count) {
> >
> > This patch takes it further, but still has the effect of fixing the number of
> > pages that drm_prime_sg_to_page_addr_arrays() returns. Something like this
> > should be included in v5.9 to prevent a regression with AMDGPU.
>
> Probably the easiest way to handle a fix for v5.9 would be to simply
> merge the latest version of this patch also to v5.9-rcX:
> https://lore.kernel.org/dri-devel/[email protected]/
>
>
> This way we would get it fixed and avoid possible conflict in the -next.
> Do you have any AMDGPU fixes for v5.9 in the queue? Maybe you can add
> that patch to the queue? Dave: would it be okay that way?
I think this should go into drm-misc for 5.9 since it's an update to
drm_prime.c. Is that patch ready to merge?
Acked-by: Alex Deucher <[email protected]>
Alex
>
> Best regards
> --
> Marek Szyprowski, PhD
> Samsung R&D Institute Poland
>
> _______________________________________________
> Linaro-mm-sig mailing list
> [email protected]
> https://lists.linaro.org/mailman/listinfo/linaro-mm-sig
Hi All,
On 25.09.2020 23:23, Alex Deucher wrote:
> On Tue, Sep 22, 2020 at 2:28 AM Marek Szyprowski
> <[email protected]> wrote:
>> On 22.09.2020 01:15, Alex Goins wrote:
>>> Tested-by: Alex Goins <[email protected]>
>>>
>>> This change fixes a regression with drm_prime_sg_to_page_addr_arrays() and
>>> AMDGPU in v5.9.
>> Thanks for testing!
>>
>>> Commit 39913934 similarly revamped AMDGPU to use sgtable helper functions. When
>>> it changed from dma_map_sg_attrs() to dma_map_sgtable(), as a side effect it
>>> started correctly updating sgt->nents to the return value of dma_map_sg_attrs().
>>> However, drm_prime_sg_to_page_addr_arrays() incorrectly uses sgt->nents to
>>> iterate over pages, rather than sgt->orig_nents, resulting in it now returning
>>> the incorrect number of pages on AMDGPU.
>>>
>>> I had written a patch that changes drm_prime_sg_to_page_addr_arrays() to use
>>> for_each_sgtable_sg() instead of for_each_sg(), iterating using sgt->orig_nents:
>>>
>>> - for_each_sg(sgt->sgl, sg, sgt->nents, count) {
>>> + for_each_sgtable_sg(sgt, sg, count) {
>>>
>>> This patch takes it further, but still has the effect of fixing the number of
>>> pages that drm_prime_sg_to_page_addr_arrays() returns. Something like this
>>> should be included in v5.9 to prevent a regression with AMDGPU.
>> Probably the easiest way to handle a fix for v5.9 would be to simply
>> merge the latest version of this patch also to v5.9-rcX:
>> https://lore.kernel.org/dri-devel/[email protected]/
>>
>>
>> This way we would get it fixed and avoid possible conflict in the -next.
>> Do you have any AMDGPU fixes for v5.9 in the queue? Maybe you can add
>> that patch to the queue? Dave: would it be okay that way?
> I think this should go into drm-misc for 5.9 since it's an update to
> drm_prime.c. Is that patch ready to merge?
> Acked-by: Alex Deucher <[email protected]>
Maarten, Maxime or Thomas: could you take this one:
https://lore.kernel.org/dri-devel/[email protected]/
also to drm-misc-fixes for v5.9-rc?
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland