dri-devel Archive on lore.kernel.org
 help / color / Atom feed
From: Marek Szyprowski <m.szyprowski@samsung.com>
To: dri-devel@lists.freedesktop.org,
	iommu@lists.linux-foundation.org, linaro-mm-sig@lists.linaro.org,
	linux-kernel@vger.kernel.org
Cc: linux-samsung-soc@vger.kernel.org,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	David Airlie <airlied@linux.ie>,
	Seung-Woo Kim <sw0312.kim@samsung.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Christoph Hellwig <hch@lst.de>,
	linux-arm-kernel@lists.infradead.org,
	Marek Szyprowski <m.szyprowski@samsung.com>
Subject: [PATCH v4 11/38] drm: exynos: fix common struct sg_table related issues
Date: Tue, 12 May 2020 11:00:31 +0200
Message-ID: <20200512090058.14910-11-m.szyprowski@samsung.com> (raw)
In-Reply-To: <20200512090058.14910-1-m.szyprowski@samsung.com>

The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function
returns the number of the created entries in the DMA address space.
However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and
dma_unmap_sg must be called with the original number of the entries
passed to the dma_map_sg().

struct sg_table is a common structure used for describing a non-contiguous
memory buffer, used commonly in the DRM and graphics subsystems. It
consists of a scatterlist with memory pages and DMA addresses (sgl entry),
as well as the number of scatterlist entries: CPU pages (orig_nents entry)
and DMA mapped pages (nents entry).

It turned out that it was a common mistake to misuse nents and orig_nents
entries, calling DMA-mapping functions with a wrong number of entries or
ignoring the number of mapped entries returned by the dma_map_sg()
function.

To avoid such issues, lets use a common dma-mapping wrappers operating
directly on the struct sg_table objects and use scatterlist page
iterators where possible. This, almost always, hides references to the
nents and orig_nents entries, making the code robust, easier to follow
and copy/paste safe.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
---
For more information, see '[PATCH v4 00/38] DRM: fix struct sg_table nents
vs. orig_nents misuse' thread:
https://lore.kernel.org/dri-devel/20200512085710.14688-1-m.szyprowski@samsung.com/T/
---
 drivers/gpu/drm/exynos/exynos_drm_g2d.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_g2d.c b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
index fcee33a..7014a8c 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_g2d.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
@@ -395,8 +395,8 @@ static void g2d_userptr_put_dma_addr(struct g2d_data *g2d,
 		return;
 
 out:
-	dma_unmap_sg(to_dma_dev(g2d->drm_dev), g2d_userptr->sgt->sgl,
-			g2d_userptr->sgt->nents, DMA_BIDIRECTIONAL);
+	dma_unmap_sgtable(to_dma_dev(g2d->drm_dev), g2d_userptr->sgt,
+			  DMA_BIDIRECTIONAL, 0);
 
 	pages = frame_vector_pages(g2d_userptr->vec);
 	if (!IS_ERR(pages)) {
@@ -511,10 +511,10 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct g2d_data *g2d,
 
 	g2d_userptr->sgt = sgt;
 
-	if (!dma_map_sg(to_dma_dev(g2d->drm_dev), sgt->sgl, sgt->nents,
-				DMA_BIDIRECTIONAL)) {
+	ret = dma_map_sgtable(to_dma_dev(g2d->drm_dev), sgt,
+			      DMA_BIDIRECTIONAL, 0);
+	if (ret) {
 		DRM_DEV_ERROR(g2d->dev, "failed to map sgt with dma region.\n");
-		ret = -ENOMEM;
 		goto err_sg_free_table;
 	}
 
-- 
1.9.1

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

  parent reply index

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20200512085722eucas1p2fbaab30e49c9ddadc64b27db856e5921@eucas1p2.samsung.com>
2020-05-12  8:57 ` [PATCH v4 00/38] DRM: fix struct sg_table nents vs. orig_nents misuse Marek Szyprowski
     [not found]   ` <CGME20200512090107eucas1p13a38ce5ce4c15cd0033acaea7b26c9b0@eucas1p1.samsung.com>
2020-05-12  9:00     ` [PATCH v4 01/38] dma-mapping: add generic helpers for mapping sgtable objects Marek Szyprowski
     [not found]       ` <CGME20200512090108eucas1p10a3571be3f60265daea3b3f1469b5e82@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 02/38] scatterlist: add generic wrappers for iterating over " Marek Szyprowski
2020-05-13 13:24           ` Robin Murphy
     [not found]       ` <CGME20200512090108eucas1p2168167ab5e1de09df0d5def83f64dbfe@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 03/38] iommu: add generic helper for mapping " Marek Szyprowski
2020-05-13  9:03           ` Joerg Roedel
2020-05-13 13:27           ` Robin Murphy
     [not found]       ` <CGME20200512090109eucas1p285ca10dceb29f43aae1c40814e2dec8d@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 04/38] drm: prime: add common helper to check scatterlist contiguity Marek Szyprowski
     [not found]       ` <CGME20200512090110eucas1p1fdf69509f401e425c45e958430a99b65@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 05/38] drm: prime: use sgtable iterators in drm_prime_sg_to_page_addr_arrays() Marek Szyprowski
     [not found]       ` <CGME20200512090110eucas1p1b8de7671df480c071718c96f8ebdbc42@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 06/38] drm: core: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200512090111eucas1p2fd703addaa7975c16a1ea2d7807cc6a6@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 07/38] drm: amdgpu: " Marek Szyprowski
     [not found]       ` <CGME20200512090111eucas1p29897737c262b467437d0775204129105@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 08/38] drm: armada: " Marek Szyprowski
     [not found]       ` <CGME20200512090112eucas1p225de9f54f7fd54346043fc8c31e7ea2d@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 09/38] drm: etnaviv: " Marek Szyprowski
     [not found]       ` <CGME20200512090112eucas1p280707473d14730b8d3054fe9b0781a05@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 10/38] drm: exynos: use common helper for a scatterlist contiguity check Marek Szyprowski
     [not found]       ` <CGME20200512090113eucas1p254a8b23dd0ee63411df200f66d193203@eucas1p2.samsung.com>
2020-05-12  9:00         ` Marek Szyprowski [this message]
     [not found]       ` <CGME20200512090114eucas1p1917c16e0312cfb191f327e6dad2f7808@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 12/38] drm: i915: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200512090114eucas1p1bc4ab112b490205283e7d2f82a9713ee@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 13/38] drm: lima: " Marek Szyprowski
     [not found]       ` <CGME20200512090115eucas1p25e71b29fa935e53e4c04f9b3789a09fc@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 14/38] drm: mediatek: use common helper for a scatterlist contiguity check Marek Szyprowski
     [not found]       ` <CGME20200512090116eucas1p2089d6eb7aa6bad4d2cbc2875c175873f@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 15/38] drm: mediatek: use common helper for extracting pages array Marek Szyprowski
     [not found]       ` <CGME20200512090116eucas1p24662e01574c0700cfe6d474280bb8df5@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 16/38] drm: msm: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200512090117eucas1p1acf4ddfe65242d28eee247ab2ca21454@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 17/38] drm: omapdrm: use common helper for extracting pages array Marek Szyprowski
     [not found]       ` <CGME20200512090117eucas1p1179ea62b61b45fae70630e66e434ffb3@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 18/38] drm: omapdrm: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200512090118eucas1p19ed5cf76c6e1e3f3bcaaefaeff7cf333@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 19/38] drm: panfrost: " Marek Szyprowski
     [not found]       ` <CGME20200512090119eucas1p2c0db485fddf17f15135f8e69e46fc097@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 20/38] drm: radeon: " Marek Szyprowski
     [not found]       ` <CGME20200512090119eucas1p2b3e1a858d8893f8d209d5c19fcbab941@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 21/38] drm: rockchip: use common helper for a scatterlist contiguity check Marek Szyprowski
     [not found]       ` <CGME20200512090120eucas1p28cc382480b2e3298b59fb6bf5ffde80b@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 22/38] drm: rockchip: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200512090120eucas1p18ae5489153837bbf5b8baa5089234c40@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 23/38] drm: tegra: " Marek Szyprowski
     [not found]       ` <CGME20200512090121eucas1p2f20e300f70ff54da15fe49cc6690f608@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 24/38] drm: v3d: " Marek Szyprowski
     [not found]       ` <CGME20200512090122eucas1p10cc3f42cb0452a8a279fcc8702e50a7a@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 25/38] drm: virtio: " Marek Szyprowski
     [not found]       ` <CGME20200512090122eucas1p155db33deb51b4bbc34c0a012e4a7361d@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 26/38] drm: vmwgfx: " Marek Szyprowski
     [not found]       ` <CGME20200512090123eucas1p268736ef6e202c23e8be77c56873f415f@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 27/38] xen: gntdev: " Marek Szyprowski
     [not found]       ` <CGME20200512090123eucas1p25758ba07ba913e5a3eeca13c7f386fdb@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 28/38] drm: host1x: " Marek Szyprowski
     [not found]       ` <CGME20200512090124eucas1p1f96fac067834c139fe1095a63b4dc2f0@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 29/38] drm: rcar-du: " Marek Szyprowski
     [not found]       ` <CGME20200512090124eucas1p20509113bdbdd1070d8265aa1af80e64a@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 30/38] dmabuf: " Marek Szyprowski
     [not found]       ` <CGME20200512090125eucas1p1f9eae024a33e92bf1468f2af4e5a1b0a@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 31/38] staging: ion: remove dead code Marek Szyprowski
     [not found]       ` <CGME20200512090126eucas1p1ad8d5dfd09fce31d9a18691a76e9fa75@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 32/38] staging: ion: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200512090127eucas1p19889d83b1c750dcdc869323e8d1946a3@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 33/38] staging: tegra-vde: " Marek Szyprowski
     [not found]       ` <CGME20200512090128eucas1p2cf31bfdca3b096585ba9f2741ef08ce0@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 34/38] misc: fastrpc: " Marek Szyprowski
     [not found]       ` <CGME20200512090128eucas1p11ee8a5e72ca37dc6b3e8a07ea094bab6@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 35/38] rapidio: " Marek Szyprowski
     [not found]       ` <CGME20200512090129eucas1p2e67c8a9adafb202970a59c3412cd887a@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 36/38] samples: vfio-mdev/mbochs: " Marek Szyprowski
     [not found]       ` <CGME20200512090129eucas1p24fa7e83acb8cde494f71ca5694279401@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 37/38] media: pci: fix common ALSA DMA-mapping related codes Marek Szyprowski
     [not found]       ` <CGME20200512090130eucas1p2eb86c5d34be56bbc81032bc0b6927d1e@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 38/38] videobuf2: use sgtable-based scatterlist wrappers Marek Szyprowski
2020-05-12 17:52           ` Ruhl, Michael J
2020-05-12 20:33             ` Marek Szyprowski
2020-05-13 12:01               ` Ruhl, Michael J
     [not found]       ` <20200512121808.GA20393@lst.de>
2020-05-12 13:00         ` [PATCH v4 01/38] dma-mapping: add generic helpers for mapping sgtable objects Marek Szyprowski
     [not found]           ` <20200512130936.GA24428@lst.de>
2020-05-12 13:19             ` Marek Szyprowski
2020-05-13 13:23       ` Robin Murphy

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200512090058.14910-11-m.szyprowski@samsung.com \
    --to=m.szyprowski@samsung.com \
    --cc=airlied@linux.ie \
    --cc=b.zolnierkie@samsung.com \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=hch@lst.de \
    --cc=iommu@lists.linux-foundation.org \
    --cc=linaro-mm-sig@lists.linaro.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-samsung-soc@vger.kernel.org \
    --cc=robin.murphy@arm.com \
    --cc=sw0312.kim@samsung.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

dri-devel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/dri-devel/0 dri-devel/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 dri-devel dri-devel/ https://lore.kernel.org/dri-devel \
		dri-devel@lists.freedesktop.org
	public-inbox-index dri-devel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.freedesktop.lists.dri-devel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git