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Tue, 12 May 2020 09:01:21 +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 , VMware Graphics , Thomas Hellstrom Subject: [PATCH v4 26/38] drm: vmwgfx: fix common struct sg_table related issues Date: Tue, 12 May 2020 11:00:46 +0200 Message-Id: <20200512090058.14910-26-m.szyprowski@samsung.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200512090058.14910-1-m.szyprowski@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrKKsWRmVeSWpSXmKPExsWy7djP87qPUnfFGcx/bGLRe+4kk8XGGetZ Lf5vm8hsceXrezaLlauPMlks2G9t8eXKQyaLTY+vsVq8OXKM0eLyrjlsFmuP3GW3OPjhCavF 51PH2Bx4PdbMW8PosffbAhaP7d8esHrc7z7O5LF5Sb3H7X+PmT0m31jO6LH7ZgObR9+WVYwe nzfJebyb/5YtgDuKyyYlNSezLLVI3y6BK+PVnXfMBackKq7/lWxgPCbSxcjJISFgItH7dxtT FyMXh5DACkaJ5ysbGCGcL4wSx7eeY4NwPjNKtO9oBSrjAGtparaFiC9nlNh/6wsTXEfrhE1s IHPZBAwlut52gdkiAq2MEid6eUCKmAX+MUlM/juLCSQhLBAk0bRiK1gRi4CqxOuvl1hANvAK 2EncvCoBcZ+8xOoNB5hBbE6g8P35f1hA5kgIHGOXaL14hRmiyEXib083G4QtLPHq+BZ2CFtG 4vTkHqiGZkaJh+fWskM4PYwSl5tmMEJUWUvcOfeLDWQzs4CmxPpd+hBhR4n/e7cxQ7zMJ3Hj rSBImBnInLRtOlSYV6KjTQiiWk1i1vF1cGsPXrgEdZqHxIXlP9ghAXQUGFpnnzJPYJSfhbBs ASPjKkbx1NLi3PTUYqO81HK94sTc4tK8dL3k/NxNjMDEdPrf8S87GHf9STrEKMDBqMTDa2Cw M06INbGsuDL3EKMEB7OSCG9LJlCINyWxsiq1KD++qDQntfgQozQHi5I4r/Gil7FCAumJJanZ qakFqUUwWSYOTqkGxu0rL01OXKw/u7Pg9zTVgJ5YpQCticcev3tbaPyh+NPvE2vWmb5+Njfp kHF1XO/pt5xB5euFub8qLP37funWBIPMulkhdrkf2vxay/3fGHO0pMxXXnjh/cLL2+Kfclx9 +/7Zf8tTvm+ii/ldZlol9FYxzRVsPG7HusBzlu259avvLj2oNEfL9L4SS3FGoqEWc1FxIgBg 0/iQSAMAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprGIsWRmVeSWpSXmKPExsVy+t/xu7qPUnfFGUzqkbPoPXeSyWLjjPWs Fv+3TWS2uPL1PZvFytVHmSwW7Le2+HLlIZPFpsfXWC3eHDnGaHF51xw2i7VH7rJbHPzwhNXi 86ljbA68HmvmrWH02PttAYvH9m8PWD3udx9n8ti8pN7j9r/HzB6Tbyxn9Nh9s4HNo2/LKkaP z5vkPN7Nf8sWwB2lZ1OUX1qSqpCRX1xiqxRtaGGkZ2hpoWdkYqlnaGwea2VkqqRvZ5OSmpNZ llqkb5egl/HqzjvmglMSFdf/SjYwHhPpYuTgkBAwkWhqtu1i5OIQEljKKNFwq4Wpi5ETKC4j cXJaAyuELSzx51oXG0TRJ0aJO/sfMYIk2AQMJbreQiREBDoZJaZ1f2QHcZgFWpgl9r75xwZS JSwQIPF54h2wUSwCqhKvv15iAVnNK2AncfOqBMQGeYnVGw4wg9icQOH78/+wgNhCAoUSj66+ ZZnAyLeAkWEVo0hqaXFuem6xkV5xYm5xaV66XnJ+7iZGYJxsO/Zzyw7GrnfBhxgFOBiVeHg7 jHbGCbEmlhVX5h5ilOBgVhLhbckECvGmJFZWpRblxxeV5qQWH2I0BbppIrOUaHI+MIbzSuIN TQ3NLSwNzY3Njc0slMR5OwQOxggJpCeWpGanphakFsH0MXFwSjUwnmV5v4r/mf1+p/j319+n bZnOlp++b1m+6VTH+0a2m302vnn/eOc05b8Sh2z5pk/8EjFrvsnadGPP25WHFusVH2BSNY8x OvBigw67oP/cNH2elacuhwur/Iro3CLic0Oq3qVIsWjdL6GoUP25M/eYT9jAbV48+esdiwcu 6TesNmjEP5POP1x3WImlOCPRUIu5qDgRAJndOeSpAgAA X-CMS-MailID: 20200512090122eucas1p155db33deb51b4bbc34c0a012e4a7361d X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20200512090122eucas1p155db33deb51b4bbc34c0a012e4a7361d X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20200512090122eucas1p155db33deb51b4bbc34c0a012e4a7361d References: <20200512085710.14688-1-m.szyprowski@samsung.com> <20200512090058.14910-1-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 Acked-by: Roland Scheidegger --- 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/vmwgfx/vmwgfx_ttm_buffer.c | 17 ++++------------- 1 file changed, 4 insertions(+), 13 deletions(-) diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c index bf0bc46..49ed6ad 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c @@ -362,8 +362,7 @@ static void vmw_ttm_unmap_from_dma(struct vmw_ttm_tt *vmw_tt) { struct device *dev = vmw_tt->dev_priv->dev->dev; - dma_unmap_sg(dev, vmw_tt->sgt.sgl, vmw_tt->sgt.nents, - DMA_BIDIRECTIONAL); + dma_unmap_sgtable(dev, vmw_tt->sgt, DMA_BIDIRECTIONAL, 0); vmw_tt->sgt.nents = vmw_tt->sgt.orig_nents; } @@ -383,16 +382,8 @@ static void vmw_ttm_unmap_from_dma(struct vmw_ttm_tt *vmw_tt) static int vmw_ttm_map_for_dma(struct vmw_ttm_tt *vmw_tt) { struct device *dev = vmw_tt->dev_priv->dev->dev; - int ret; - - ret = dma_map_sg(dev, vmw_tt->sgt.sgl, vmw_tt->sgt.orig_nents, - DMA_BIDIRECTIONAL); - if (unlikely(ret == 0)) - return -ENOMEM; - vmw_tt->sgt.nents = ret; - - return 0; + return dma_map_sgtable(dev, vmw_tt->sgt, DMA_BIDIRECTIONAL, 0); } /** @@ -449,10 +440,10 @@ static int vmw_ttm_map_dma(struct vmw_ttm_tt *vmw_tt) if (unlikely(ret != 0)) goto out_sg_alloc_fail; - if (vsgt->num_pages > vmw_tt->sgt.nents) { + if (vsgt->num_pages > vmw_tt->sgt.orig_nents) { uint64_t over_alloc = sgl_size * (vsgt->num_pages - - vmw_tt->sgt.nents); + vmw_tt->sgt.orig_nents); ttm_mem_global_free(glob, over_alloc); vmw_tt->sg_alloc_size -= over_alloc; -- 1.9.1