| Message ID | 20200513133245.6408-5-m.szyprowski@samsung.com |
|---|---|
| State | New |
| Headers | show |
| Series | DRM: fix struct sg_table nents vs. orig_nents misuse | expand |
Tested-by: Alex Goins <agoins@nvidia.com> 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 <m.szyprowski@samsung.com> > --- > 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/20200513132114.6046-1-m.szyprowski@samsung.com/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 > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel > _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
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 <agoins@nvidia.com> > > > > 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/20200904131711.12950-3-m.szyprowski@samsung.com/ Tested-by: Alex Goins <agoins@nvidia.com> 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 > > _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
On Tue, Sep 22, 2020 at 2:28 AM Marek Szyprowski <m.szyprowski@samsung.com> wrote: > > Hi Alex, > > On 22.09.2020 01:15, Alex Goins wrote: > > Tested-by: Alex Goins <agoins@nvidia.com> > > > > 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/20200904131711.12950-3-m.szyprowski@samsung.com/ > > > 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 <alexander.deucher@amd.com> Alex > > Best regards > -- > Marek Szyprowski, PhD > Samsung R&D Institute Poland > > _______________________________________________ > Linaro-mm-sig mailing list > Linaro-mm-sig@lists.linaro.org > https://lists.linaro.org/mailman/listinfo/linaro-mm-sig _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
Hi All, On 25.09.2020 23:23, Alex Deucher wrote: > On Tue, Sep 22, 2020 at 2:28 AM Marek Szyprowski > <m.szyprowski@samsung.com> wrote: >> On 22.09.2020 01:15, Alex Goins wrote: >>> Tested-by: Alex Goins <agoins@nvidia.com> >>> >>> 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/20200904131711.12950-3-m.szyprowski@samsung.com/ >> >> >> 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 <alexander.deucher@amd.com> Maarten, Maxime or Thomas: could you take this one: https://lore.kernel.org/dri-devel/20200904131711.12950-3-m.szyprowski@samsung.com/ also to drm-misc-fixes for v5.9-rc? Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
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);
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 <m.szyprowski@samsung.com> --- 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/20200513132114.6046-1-m.szyprowski@samsung.com/T/ --- drivers/gpu/drm/drm_prime.c | 47 ++++++++++++++------------------------------- 1 file changed, 14 insertions(+), 33 deletions(-) -- 1.9.1 _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel