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Wed, 13 May 2020 13:33:03 +0000 (GMT) From: Marek Szyprowski To: dri-devel@lists.freedesktop.org, iommu@lists.linux-foundation.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org Cc: Marek Szyprowski , Christoph Hellwig , Robin Murphy , Bartlomiej Zolnierkiewicz , linux-arm-kernel@lists.infradead.org, David Airlie , Daniel Vetter , Inki Dae , Seung-Woo Kim , linux-samsung-soc@vger.kernel.org Subject: [PATCH v5 11/38] drm: exynos: fix common struct sg_table related issues Date: Wed, 13 May 2020 15:32:18 +0200 Message-Id: <20200513133245.6408-11-m.szyprowski@samsung.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200513133245.6408-1-m.szyprowski@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA0WSe0hTURzHO7t3d9fh5DYNDxZaA6MEZ1bEXVYWRl0IQoKCisyVFzWf7PqG TBNT5iN1WVMiRbOZr5lTE5f5qJyPUFEzdYrK0nSlRpqRhrXr1frve77fz/f8Dj8Ojojr+Q54 YGgErQiVB0swIVrf/qvHlfip9zlQpIZkRk8nj3yh1vLJP/XZCDn4YxEjn5e/45E5E1koWdjs QS4PTvHIGtMQnxxofIyR6t7XPLLy7biAbP32iU+qVXPYSRuq4kkFoJpWClHq5cokn5pIM/Ao 3dM7lHHdhFCqYQ2g9CMJGJVZWwaopRpHb+EV4TE/Ojgwila4nfAVBhhSygThHXYxdd3LSALQ bFcCKxwSh+H9jgpMCYS4mCgF8PNCooANxMQygA2lLlywBOBi8Sxvq1FdsCbgAg2A44tGwB0s jZneTJSlMMIdKueVGKvtiGQAOzKsWQghUhE4lF1gaeC4LXEBZlZeYhmUcIZ5FeMbvIg4Drv6 xgTcNCdYXt2CsNrK4pvHmlH2Hki0C6CuYA7joNNwYSYZ5bQtNBtqN8u7YLcqfbOQBOBUT6WA O6QDOHBXDTjKA471rGLsixBiP9Q2unH2KTg+38ZjbUjYwOH5jYUhFplT/wjhbBFMvSfm6L0w 31D1b2xrXz/CaQp2KqcRbkFvACzMXeRnAaf8/8MKASgD9nQkE+JPMwdD6WgpIw9hIkP9pTfD QmqA5Td1rxuWG0Dj7xttgMCBxFpEjup9xHx5FBMb0gYgjkjsROe1FkvkJ4+NoxVh1xWRwTTT BnbiqMRedKho7pqY8JdH0EE0HU4rtlIebuWQAKhnI57ZiSUBJbIvjvkTSSlBIrlX92hanL1L 8b6jzpLhbXyH+PgY/axpaEHg9UpflSdTT2ovy4Ie5MYlmR/WmZvCjM5n3c+ZGKNKPNP1scV1 tZ/Y44uVe0elVcq+itM9pWvfY1RXNR+ipdZnEJ1y9JamYcfti13vj8SW7tatTEtQJkDu7oIo GPlfXwZqpUkDAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprJIsWRmVeSWpSXmKPExsVy+t/xu7oC33fHGaw4yGrRe+4kk8XGGetZ Lf5vm8hsceXrezaLlauPMllMuj+BxWLBfmuLL1ceMllsenyN1eLyrjlsFjPO72OyWHvkLrvF wQ9PWC1mTH7J5sDnsWbeGkaPvd8WsHhs//aA1eN+93Emj81L6j1u/3vM7DH5xnJGj903G9g8 +rasYvT4vEkugCtKz6Yov7QkVSEjv7jEVina0MJIz9DSQs/IxFLP0Ng81srIVEnfziYlNSez LLVI3y5BL+N4+yr2ghMiFVtPf2FuYFwu2MXIySEhYCKxYf5v9i5GLg4hgaWMEgteTmWCSMhI nJzWwAphC0v8udbFBlH0iVHiwrfJzCAJNgFDia63EAkRgU5GiWndH8FGMQtMYJa437KaEaRK WCBAouncIrAOFgFViZlr7rKB2LwCthKnLtxhh1ghL7F6wwGwGk6g+Ks7+1lAbCGBfIm9i/ex TWDkW8DIsIpRJLW0ODc9t9hIrzgxt7g0L10vOT93EyMwWrYd+7llB2PXu+BDjAIcjEo8vBa3 dscJsSaWFVfmHmKU4GBWEuH1Ww8U4k1JrKxKLcqPLyrNSS0+xGgKdNREZinR5HxgJOeVxBua GppbWBqaG5sbm1koifN2CByMERJITyxJzU5NLUgtgulj4uCUamAMeKu88P9p9srvnsG9edE+ b64/K5sQ/+fDitA8NxPX+WH3lq4yyT89k6/vO6OHiEDG+y2fIsTfCvK9qT0927z4GP+x2o3t 354opPAZSLM9Tm3bZ5DuGrztlOza4vivoXrPmvj7U+Yv2eDi3TyFtcFaw/TRVoN7+bNjI7RU A/KSdXvZ+S413lRiKc5INNRiLipOBABIc1RErAIAAA== X-CMS-MailID: 20200513133304eucas1p1114334ce7250cf8189553a22080b69f4 X-Msg-Generator: CA X-RootMTR: 20200513133304eucas1p1114334ce7250cf8189553a22080b69f4 X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20200513133304eucas1p1114334ce7250cf8189553a22080b69f4 References: <20200513132114.6046-1-m.szyprowski@samsung.com> <20200513133245.6408-1-m.szyprowski@samsung.com> Sender: linux-samsung-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-samsung-soc@vger.kernel.org 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 --- 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/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; }