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Fri, 19 Jun 2020 10:36:55 +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 , Russell King Subject: [PATCH v7 05/36] drm: armada: fix common struct sg_table related issues Date: Fri, 19 Jun 2020 12:36:05 +0200 Message-Id: <20200619103636.11974-6-m.szyprowski@samsung.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200619103636.11974-1-m.szyprowski@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrIKsWRmVeSWpSXmKPExsWy7djPc7oeU9/EGWw4YGrRe+4kk8XGGetZ Lf5vm8hsceXrezaLlauPMlks2G9t8eXKQyaLTY+vsVpc3jWHzeLQ1L2MFmuP3GW3OPjhCasD j8eaeWsYPS5fu8jssffbAhaP7d8esHrc7z7O5LF5Sb3H7X+PmT0m31jO6LH7ZgObR9+WVYwe nzfJBXBHcdmkpOZklqUW6dslcGV8nzSBveC8eMWdmfOYGxj3CHcxcnJICJhIvJ0ylbmLkYtD SGAFo0R3yx0mCOcLo8Sm541Qmc+MEgvXTWWEabn76CkbiC0ksJxRYvGTRLiOnx0XWUESbAKG El1vu8CKRARaGSVO9PKAFDELHGCSaHv3GmgHB4ewQJDE7HZtkBoWAVWJxq7VYL28ArYSfz9u g1omL7F6wwFmEJtTwE7idctBVpA5EgL72CXu3f3ABlHkIjH77QIWCFtY4tXxLewQtozE6ck9 LBANzYwSD8+tZYdwehglLjfNgFphLXHn3C82kIuYBTQl1u/Shwg7SvxvfsEMEpYQ4JO48VYQ JMwMZE7aNh0qzCvR0SYEUa0mMev4Ori1By9cYoawPSRO7NnACAmgiYwSyzsusE5glJ+FsGwB I+MqRvHU0uLc9NRio7zUcr3ixNzi0rx0veT83E2MwIR0+t/xLzsYd/1JOsQowMGoxMP7IuR1 nBBrYllxZe4hRgkOZiURXqezp+OEeFMSK6tSi/Lji0pzUosPMUpzsCiJ8xovehkrJJCeWJKa nZpakFoEk2Xi4JRqYFz29vWuDUtXcPf9a3p8ymvOC7V3WS9eZbF7GhZdN3ij3irmwRSb7nhY 8HR6/c7Ckm8rcyqt9LdOqPHdNfWv7aWfD9M5nyezBsfvFVmaGsB1fbILw9olBQIuDeL3CoNU vgZM+3c7nDmv/6H90jkT5/ZPXBAVN6Xa+wTvLsc/zBX/Xu+N6WrIllFiKc5INNRiLipOBABb TQk4RAMAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprEIsWRmVeSWpSXmKPExsVy+t/xe7oeU9/EGXx4LmzRe+4kk8XGGetZ Lf5vm8hsceXrezaLlauPMlks2G9t8eXKQyaLTY+vsVpc3jWHzeLQ1L2MFmuP3GW3OPjhCasD j8eaeWsYPS5fu8jssffbAhaP7d8esHrc7z7O5LF5Sb3H7X+PmT0m31jO6LH7ZgObR9+WVYwe nzfJBXBH6dkU5ZeWpCpk5BeX2CpFG1oY6RlaWugZmVjqGRqbx1oZmSrp29mkpOZklqUW6dsl 6GV8nzSBveC8eMWdmfOYGxj3CHcxcnJICJhI3H30lA3EFhJYyiix+Jg2RFxG4uS0BlYIW1ji z7UuoBouoJpPjBIz2x+DJdgEDCW63kIkRAQ6GSWmdX9kB3GYBY4xSSz89ZGli5GDQ1ggQGLq bx2QBhYBVYnGrtVgzbwCthJ/P25jhNggL7F6wwFmEJtTwE7idctBVoiLbCWWL3jPPIGRbwEj wypGkdTS4tz03GIjveLE3OLSvHS95PzcTYzA+Nh27OeWHYxd74IPMQpwMCrx8L4IeR0nxJpY VlyZe4hRgoNZSYTX6ezpOCHelMTKqtSi/Pii0pzU4kOMpkBHTWSWEk3OB8ZuXkm8oamhuYWl obmxubGZhZI4b4fAwRghgfTEktTs1NSC1CKYPiYOTqkGxsPJvcyZ4q6Tq3Ytt3znVCF0KUq3 96Dh59rtfadfNeV0FN/KtfwqtyRueozXrNr0n2afnjCb8ecEc2RFfI/0eBWjuq94/q8ExmCL zskc+yLmSrDziyqfWX6kqTev8HFe3banhc9/SRuF/XfavO9ep0O/1bsN3I8m/jl1OuVbQZx5 X/T/lrQ8JZbijERDLeai4kQARp17FKUCAAA= X-CMS-MailID: 20200619103656eucas1p262a08b701244745a547a0c38f26f83af X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20200619103656eucas1p262a08b701244745a547a0c38f26f83af X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20200619103656eucas1p262a08b701244745a547a0c38f26f83af References: <20200619103636.11974-1-m.szyprowski@samsung.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 --- drivers/gpu/drm/armada/armada_gem.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/armada/armada_gem.c b/drivers/gpu/drm/armada/armada_gem.c index 8005614d2e6b..bedd8937d8a1 100644 --- a/drivers/gpu/drm/armada/armada_gem.c +++ b/drivers/gpu/drm/armada/armada_gem.c @@ -395,7 +395,7 @@ armada_gem_prime_map_dma_buf(struct dma_buf_attachment *attach, mapping = dobj->obj.filp->f_mapping; - for_each_sg(sgt->sgl, sg, count, i) { + for_each_sgtable_sg(sgt, sg, i) { struct page *page; page = shmem_read_mapping_page(mapping, i); @@ -407,8 +407,8 @@ armada_gem_prime_map_dma_buf(struct dma_buf_attachment *attach, sg_set_page(sg, page, PAGE_SIZE, 0); } - if (dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir) == 0) { - num = sgt->nents; + if (dma_map_sgtable(attach->dev, sgt, dir, 0)) { + num = count; goto release; } } else if (dobj->page) { @@ -418,7 +418,7 @@ armada_gem_prime_map_dma_buf(struct dma_buf_attachment *attach, sg_set_page(sgt->sgl, dobj->page, dobj->obj.size, 0); - if (dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir) == 0) + if (dma_map_sgtable(attach->dev, sgt, dir, 0)) goto free_table; } else if (dobj->linear) { /* Single contiguous physical region - no struct page */ @@ -449,11 +449,11 @@ static void armada_gem_prime_unmap_dma_buf(struct dma_buf_attachment *attach, int i; if (!dobj->linear) - dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents, dir); + dma_unmap_sgtable(attach->dev, sgt, dir, 0); if (dobj->obj.filp) { struct scatterlist *sg; - for_each_sg(sgt->sgl, sg, sgt->nents, i) + for_each_sgtable_sg(sgt, sg, i) put_page(sg_page(sg)); } -- 2.17.1