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Thu, 18 Jun 2020 15:40:29 +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 , Roland Scheidegger Subject: [PATCH v6 23/36] drm: vmwgfx: fix common struct sg_table related issues Date: Thu, 18 Jun 2020 17:39:44 +0200 Message-Id: <20200618153956.29558-24-m.szyprowski@samsung.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200618153956.29558-1-m.szyprowski@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrGKsWRmVeSWpSXmKPExsWy7djPc7rvul7HGVw7wm/Re+4kk8XGGetZ Lf5vm8hsceXrezaLlauPMlks2G9t8eXKQyaLTY+vsVq8OXKM0eLyrjlsFmuP3GW3OPjhCavF 6k5HB16PNfPWMHrs/baAxWP7twesHve7jzN5bF5S73H732Nmj8k3ljN67L7ZwObRt2UVo8fn TXIe7+a/ZQvgjuKySUnNySxLLdK3S+DK+Nb9lL2gT7xia8sv9gbGBcJdjJwcEgImEkf3z2ft YuTiEBJYwSix5uBnNgjnC6PEwqlXGSGcz4wSd3ufsMO0vHx+DqpqOaPElTfbWOFaOj4uZQSp YhMwlOh628UGYosItDJKnOjlASliFvjLJHHp8SRWkISwQJDE2nmHmUBsFgFViXU/5oE18ArY STxa9I4JYp28xOoNB5hBbE6g+OnjrWDbJAQOsUs8/dIFVeQisah9IpQtLPHq+BaoW2UkTk/u YYFoaGaUeHhuLTuE08MocblpBiNElbXEnXO/gFZzAN2nKbF+lz5E2FHiXt8mRpCwhACfxI23 giBhZiBz0rbpzBBhXomONiGIajWJWcfXwa09eOESM4TtIbH48CWwRUICExklbl1LnMAoPwth 1wJGxlWM4qmlxbnpqcWGeanlesWJucWleel6yfm5mxiBqen0v+OfdjB+vZR0iFGAg1GJh9ch /HWcEGtiWXFl7iFGCQ5mJRFep7On44R4UxIrq1KL8uOLSnNSiw8xSnOwKInzGi96GSskkJ5Y kpqdmlqQWgSTZeLglGpgtPZoK9vKO/PDjoMTWT5fajvOLT75rPH6exHblf8e3cbteevg9L7y 5ZeaCrKnl7ix//LT1ZsyX7lSTa3W/9zFui3a4f6y0SI6q58vc5u7zqpVlnl1gHZuc07B51su BvMUA52nXMy2Vl8dckMj7EnPHG3JZaJe842Cly9Kfl3WmJwnovRG/MIDJZbijERDLeai4kQA AgRoZ0kDAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprOIsWRmVeSWpSXmKPExsVy+t/xu7pvu17HGby5aWLRe+4kk8XGGetZ Lf5vm8hsceXrezaLlauPMlks2G9t8eXKQyaLTY+vsVq8OXKM0eLyrjlsFmuP3GW3OPjhCavF 6k5HB16PNfPWMHrs/baAxWP7twesHve7jzN5bF5S73H732Nmj8k3ljN67L7ZwObRt2UVo8fn TXIe7+a/ZQvgjtKzKcovLUlVyMgvLrFVija0MNIztLTQMzKx1DM0No+1MjJV0rezSUnNySxL LdK3S9DL+Nb9lL2gT7xia8sv9gbGBcJdjJwcEgImEi+fn2PrYuTiEBJYyihxZH0jI0RCRuLk tAZWCFtY4s+1LqiiT4wSDzfPZANJsAkYSnS9hUiICHQySkzr/sgOkmAWaGaWOP+yFsQWFgiQ WH/iIFicRUBVYt2PeWDNvAJ2Eo8WvWOC2CAvsXrDAWYQmxMofvp4K9hmIQFbiecf2tgmMPIt YGRYxSiSWlqcm55bbKRXnJhbXJqXrpecn7uJERgp24793LKDsetd8CFGAQ5GJR7eFyGv44RY E8uKK3MPMUpwMCuJ8DqdPR0nxJuSWFmVWpQfX1Sak1p8iNEU6KiJzFKiyfnAKM4riTc0NTS3 sDQ0NzY3NrNQEuftEDgYIySQnliSmp2aWpBaBNPHxMEp1cC45fRs5a9lRQ57tS6s5W9+pSJs Zrd6qrnJpC9PXX5u62TJn/PHMY3/RaOg2mW9z3O/2iZnuasse+f15rqoygWHBW9emGydxMmd U8617YTFtCuf73U2vjzgc7u+4i+7d9HkstN/ReU1vCq3FF4TKdnz8bwX04qAeG1mzqB19lbR RyJfSK7zm2arxFKckWioxVxUnAgANn8hQqoCAAA= X-CMS-MailID: 20200618154029eucas1p274f275e89dc985634bbd309823ad0f0d X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20200618154029eucas1p274f275e89dc985634bbd309823ad0f0d X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20200618154029eucas1p274f275e89dc985634bbd309823ad0f0d References: <20200618153956.29558-1-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 --- 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 bf0bc4697959..49ed6add6969 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; -- 2.17.1