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From: Alex Goins <agoins@nvidia.com>
To: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	David Airlie <airlied@linux.ie>,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
	linaro-mm-sig@lists.linaro.org, iommu@lists.linux-foundation.org,
	Thomas Zimmermann <tzimmermann@suse.de>,
	Robin Murphy <robin.murphy@arm.com>,
	Christoph Hellwig <hch@lst.de>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v5 05/38] drm: prime: use sgtable iterators in drm_prime_sg_to_page_addr_arrays()
Date: Mon, 21 Sep 2020 18:15:20 -0500	[thread overview]
Message-ID: <alpine.DEB.2.20.2009211803580.19454@agoins-DiGiTS> (raw)
In-Reply-To: <20200513133245.6408-5-m.szyprowski@samsung.com>

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
> 
_______________________________________________
iommu mailing list
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  reply	other threads:[~2020-09-21 23:36 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20200513132127eucas1p23f6be10bbd627e69e36d2451068b3204@eucas1p2.samsung.com>
2020-05-13 13:21 ` [PATCH v5 00/38] DRM: fix struct sg_table nents vs. orig_nents misuse Marek Szyprowski
     [not found]   ` <CGME20200513133256eucas1p273110d0c8f67e52fc7385acef776efaa@eucas1p2.samsung.com>
2020-05-13 13:32     ` [PATCH v5 01/38] dma-mapping: add generic helpers for mapping sgtable objects Marek Szyprowski
     [not found]       ` <CGME20200513133257eucas1p1613a28a71a6c328c406397f7094534d1@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 02/38] scatterlist: add generic wrappers for iterating over " Marek Szyprowski
     [not found]       ` <CGME20200513133258eucas1p2e8ffb90e5553c12419a5af5261b48f5e@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 03/38] iommu: add generic helper for mapping " Marek Szyprowski
     [not found]       ` <CGME20200513133258eucas1p1eba6e0ced0c749655f028206d5f84b7a@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 04/38] drm: prime: add common helper to check scatterlist contiguity Marek Szyprowski
     [not found]       ` <CGME20200513133259eucas1p273f0e05005b7b1158d884295d35745fd@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 05/38] drm: prime: use sgtable iterators in drm_prime_sg_to_page_addr_arrays() Marek Szyprowski
2020-09-21 23:15           ` Alex Goins [this message]
2020-09-22  6:27             ` Marek Szyprowski
2020-09-22 21:12               ` Alex Goins
2020-09-25 21:23               ` [Linaro-mm-sig] " Alex Deucher
2020-09-30  7:15                 ` Marek Szyprowski
     [not found]       ` <CGME20200513133300eucas1p2fced04876641789a0f5623e70c910690@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 06/38] drm: core: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200513133301eucas1p244d094c774ad0efd5ea9125747d5cb1b@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 07/38] drm: amdgpu: " Marek Szyprowski
     [not found]       ` <CGME20200513133301eucas1p28c059d25e488ed5ec10feb8f414a1af2@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 08/38] drm: armada: " Marek Szyprowski
     [not found]       ` <CGME20200513133302eucas1p1edbd033e0137d0c973f82c409d3a4e5d@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 09/38] drm: etnaviv: " Marek Szyprowski
     [not found]       ` <CGME20200513133303eucas1p1e3ede8aa38f730d2be317dff27c03019@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 10/38] drm: exynos: use common helper for a scatterlist contiguity check Marek Szyprowski
     [not found]       ` <CGME20200513133304eucas1p1114334ce7250cf8189553a22080b69f4@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 11/38] drm: exynos: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200513133304eucas1p2d24ddf9d7d60aad254486010db86e6bc@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 12/38] drm: i915: " Marek Szyprowski
     [not found]       ` <CGME20200513133305eucas1p15187ed8fa1e4af181cafa5c65ddab4cd@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 13/38] drm: lima: " Marek Szyprowski
2020-05-18  1:27           ` Qiang Yu
     [not found]       ` <CGME20200513133306eucas1p1ab15386cc4bbcf09052a8175d3660997@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 14/38] drm: mediatek: use common helper for a scatterlist contiguity check Marek Szyprowski
     [not found]       ` <CGME20200513133307eucas1p1da70ed30775467792f4898ccce829d02@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 15/38] drm: mediatek: use common helper for extracting pages array Marek Szyprowski
     [not found]       ` <CGME20200513133308eucas1p205607f34ec3d6df747e21c9b27204ca3@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 16/38] drm: msm: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200513133308eucas1p248892466634483dfa3b23f11e4da0e68@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 17/38] drm: omapdrm: use common helper for extracting pages array Marek Szyprowski
     [not found]       ` <CGME20200513133309eucas1p1b5b2505556566570e6fb3433397c6168@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 18/38] drm: omapdrm: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200513133310eucas1p176c920345e7f05f670e26e330b358d7f@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 19/38] drm: panfrost: " Marek Szyprowski
2020-05-14 13:51           ` Rob Herring
     [not found]       ` <CGME20200513133311eucas1p261d84f947b03e4fc733137048aab55fb@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 20/38] drm: radeon: " Marek Szyprowski
     [not found]       ` <CGME20200513133312eucas1p15e5e3bb3ba8e74b923fdccc7decab375@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 21/38] drm: rockchip: use common helper for a scatterlist contiguity check Marek Szyprowski
     [not found]       ` <CGME20200513133312eucas1p2fc1186c0aeee2367898fc0c146f1ed52@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 22/38] drm: rockchip: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200513133313eucas1p1fa06e23680b6d983578f598166e64cd0@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 23/38] drm: tegra: " Marek Szyprowski
     [not found]       ` <CGME20200513133314eucas1p1a607b556e32887e7f5ca60eb09a476c6@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 24/38] drm: v3d: " Marek Szyprowski
2020-05-13 21:51           ` Eric Anholt
     [not found]       ` <CGME20200513133314eucas1p2f04e32d65e71c613a2a9aacb29064a7d@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 25/38] drm: virtio: " Marek Szyprowski
2020-05-15 10:12           ` Gerd Hoffmann
     [not found]       ` <CGME20200513133315eucas1p17499a099b78c332b30911345c3963368@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 26/38] drm: vmwgfx: " Marek Szyprowski
     [not found]       ` <CGME20200513133316eucas1p2ad01d27ea4388cb50424bcf112d710ef@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 27/38] xen: gntdev: " Marek Szyprowski
2020-05-18  5:17           ` Jürgen Groß
     [not found]       ` <CGME20200513133317eucas1p25446bcdce5220030c16477e1992385ff@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 28/38] drm: host1x: " Marek Szyprowski
     [not found]       ` <CGME20200513133317eucas1p27aead4025db2da13e5b7c3e14a7cd79d@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 29/38] drm: rcar-du: " Marek Szyprowski
2020-05-13 14:23           ` Laurent Pinchart
     [not found]       ` <CGME20200513133318eucas1p1dd6c1ac6a777874c115070d8b5197f34@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 30/38] dmabuf: " Marek Szyprowski
2020-05-15 10:13           ` Gerd Hoffmann
     [not found]       ` <CGME20200513133319eucas1p2eaae7e606163ec1b211a07a80a52655d@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 31/38] staging: ion: remove dead code Marek Szyprowski
     [not found]       ` <CGME20200513133320eucas1p14cc8a7155b3d9ac2e0e30db2128c1477@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 32/38] staging: ion: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200513133321eucas1p13acea3aa6219ce5f7076c7677ef9eae3@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 33/38] staging: tegra-vde: " Marek Szyprowski
2020-05-14 20:07           ` Dmitry Osipenko
     [not found]       ` <CGME20200513133322eucas1p19b55463a3926b7c1459034f2b02969f8@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 34/38] misc: fastrpc: " Marek Szyprowski
     [not found]       ` <CGME20200513133323eucas1p1344fe42c8710f0ed84cf3c9fdb5ca515@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 35/38] rapidio: " Marek Szyprowski
     [not found]       ` <CGME20200513133323eucas1p1519f5901d2a4ee85b781fcc36e9601f7@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 36/38] samples: vfio-mdev/mbochs: " Marek Szyprowski
     [not found]       ` <CGME20200513133324eucas1p25dc380046c516ca8f07677ed14f93e63@eucas1p2.samsung.com>
2020-05-13 13:32         ` [PATCH v5 37/38] media: pci: fix common ALSA DMA-mapping related codes Marek Szyprowski
     [not found]       ` <CGME20200513133325eucas1p1c8faf557b23b5d171b7c328eca5f6482@eucas1p1.samsung.com>
2020-05-13 13:32         ` [PATCH v5 38/38] videobuf2: use sgtable-based scatterlist wrappers Marek Szyprowski
2020-05-13 13:47   ` [PATCH v5 00/38] DRM: fix struct sg_table nents vs. orig_nents misuse Christoph Hellwig
2020-05-26  7:01     ` Marek Szyprowski
2020-05-26 11:31       ` Daniel Vetter
     [not found]   ` <CGME20200522125708eucas1p233b80b0741f087a84d47f24b6d91985f@eucas1p2.samsung.com>
2020-05-22 12:56     ` [PATCH v5 39/38] drm: xen: fix common struct sg_table related issues Marek Szyprowski

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