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d="scan'208";a="404882026" Received: from orsmsx601.amr.corp.intel.com ([10.22.229.14]) by fmsmga001.fm.intel.com with ESMTP; 01 Sep 2020 12:38:58 -0700 Received: from orsmsx610.amr.corp.intel.com (10.22.229.23) by ORSMSX601.amr.corp.intel.com (10.22.229.14) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1713.5; Tue, 1 Sep 2020 12:38:58 -0700 Received: from orsmsx611.amr.corp.intel.com (10.22.229.24) by ORSMSX610.amr.corp.intel.com (10.22.229.23) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1713.5; Tue, 1 Sep 2020 12:38:57 -0700 Received: from orsmsx611.amr.corp.intel.com ([10.22.229.24]) by ORSMSX611.amr.corp.intel.com ([10.22.229.24]) with mapi id 15.01.1713.004; Tue, 1 Sep 2020 12:38:57 -0700 From: "Ruhl, Michael J" To: Marek Szyprowski , "dri-devel@lists.freedesktop.org" , "iommu@lists.linux-foundation.org" , "linaro-mm-sig@lists.linaro.org" , "linux-kernel@vger.kernel.org" Subject: RE: [Intel-gfx] [PATCH v9 08/32] drm: i915: fix common struct sg_table related issues Thread-Topic: [Intel-gfx] [PATCH v9 08/32] drm: i915: fix common struct sg_table related issues Thread-Index: AQHWe3Ml/rRJPBw9lEWMq6REwJ0ovqlUN/gw Date: Tue, 1 Sep 2020 19:38:57 +0000 Message-ID: <259df561c4bb4ef484799e3776dbb402@intel.com> References: <20200826063316.23486-1-m.szyprowski@samsung.com> <20200826063316.23486-9-m.szyprowski@samsung.com> In-Reply-To: <20200826063316.23486-9-m.szyprowski@samsung.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: dlp-product: dlpe-windows dlp-reaction: no-action dlp-version: 11.5.1.3 x-originating-ip: [10.22.254.132] MIME-Version: 1.0 Cc: Bartlomiej Zolnierkiewicz , David Airlie , "intel-gfx@lists.freedesktop.org" , Robin Murphy , Christoph Hellwig , "linux-arm-kernel@lists.infradead.org" X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" >-----Original Message----- >From: Intel-gfx On Behalf Of >Marek Szyprowski >Sent: Wednesday, August 26, 2020 2:33 AM >To: dri-devel@lists.freedesktop.org; iommu@lists.linux-foundation.org; >linaro-mm-sig@lists.linaro.org; linux-kernel@vger.kernel.org >Cc: Bartlomiej Zolnierkiewicz ; David Airlie >; intel-gfx@lists.freedesktop.org; Robin Murphy >; Christoph Hellwig ; linux-arm- >kernel@lists.infradead.org; Marek Szyprowski > >Subject: [Intel-gfx] [PATCH v9 08/32] drm: i915: fix common struct sg_table >related issues > >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. > >This driver creatively uses sg_table->orig_nents to store the size of the >allocated scatterlist and ignores the number of the entries returned by >dma_map_sg function. The sg_table->orig_nents is (mis)used to properly >free the (over)allocated scatterlist. > >This patch only introduces the common DMA-mapping wrappers operating >directly on the struct sg_table objects to the dmabuf related functions, >so the other drivers, which might share buffers with i915 could rely on >the properly set nents and orig_nents values. > >Signed-off-by: Marek Szyprowski >--- > drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 11 +++-------- > drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c | 7 +++---- > 2 files changed, 6 insertions(+), 12 deletions(-) > >diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >index 2679380159fc..8a988592715b 100644 >--- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >+++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >@@ -48,12 +48,9 @@ static struct sg_table *i915_gem_map_dma_buf(struct >dma_buf_attachment *attachme > src = sg_next(src); > } > >- if (!dma_map_sg_attrs(attachment->dev, >- st->sgl, st->nents, dir, >- DMA_ATTR_SKIP_CPU_SYNC)) { >- ret = -ENOMEM; You have dropped this error value. Do you now if this is a benign loss? M >+ ret = dma_map_sgtable(attachment->dev, st, dir, >DMA_ATTR_SKIP_CPU_SYNC); >+ if (ret) > goto err_free_sg; >- } > > return st; > >@@ -73,9 +70,7 @@ static void i915_gem_unmap_dma_buf(struct >dma_buf_attachment *attachment, > { > struct drm_i915_gem_object *obj = dma_buf_to_obj(attachment- >>dmabuf); > >- dma_unmap_sg_attrs(attachment->dev, >- sg->sgl, sg->nents, dir, >- DMA_ATTR_SKIP_CPU_SYNC); >+ dma_unmap_sgtable(attachment->dev, sg, dir, >DMA_ATTR_SKIP_CPU_SYNC); > sg_free_table(sg); > kfree(sg); > >diff --git a/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c >b/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c >index debaf7b18ab5..be30b27e2926 100644 >--- a/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c >+++ b/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c >@@ -28,10 +28,9 @@ static struct sg_table *mock_map_dma_buf(struct >dma_buf_attachment *attachment, > sg = sg_next(sg); > } > >- if (!dma_map_sg(attachment->dev, st->sgl, st->nents, dir)) { >- err = -ENOMEM; >+ err = dma_map_sgtable(attachment->dev, st, dir, 0); >+ if (err) > goto err_st; >- } > > return st; > >@@ -46,7 +45,7 @@ static void mock_unmap_dma_buf(struct >dma_buf_attachment *attachment, > struct sg_table *st, > enum dma_data_direction dir) > { >- dma_unmap_sg(attachment->dev, st->sgl, st->nents, dir); >+ dma_unmap_sgtable(attachment->dev, st, dir, 0); > sg_free_table(st); > kfree(st); > } >-- >2.17.1 > >_______________________________________________ >Intel-gfx mailing list >Intel-gfx@lists.freedesktop.org >https://lists.freedesktop.org/mailman/listinfo/intel-gfx _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu