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Fri, 4 Sep 2020 13:35:05 +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 v10 20/30] drm: vmwgfx: fix common struct sg_table related issues Date: Fri, 4 Sep 2020 15:17:01 +0200 Message-Id: <20200904131711.12950-21-m.szyprowski@samsung.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200904131711.12950-1-m.szyprowski@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA0VSfSxVYRz2nq97yK3TZfOOlu1uWpnI+OOYplhrZ7XKFIsW3XLCcNm9iFZL WY0rn0lYYsrX9S0uaVZuIvlI9xKNREw0inyUEt3TufTf83ue3/M+z357SVTUgJuTQdIIViaV hIgJI0zVtvJmr8LNw29folZAJ/V0IHRNVhVOr6vSULpv6RtBl5a9ROj8Z870Yt8YQteOv8Pp mdY2QGub7hN0ResHAd0yN4HTZQmuB4VM+YNywDQv52NMw/IoznxMbEeYx4+uMUNr4yhzZ7AY ME/fxxJMcp0SMAu1O5mvebOE+xYfo/3+bEhQFCuzczlnFDg9v4KFp5pFrxYWIbGgwEQBDElI OcK33YsCBTAiRVQJgJ9WVAQ/LAL4eaAe44cFALWaXLBhGRmN1wvFACp/p4NNi/Z1KcZtEZQ9 VMwqCA6bUjcBfJVkzC2h1B8EasbTcU4woU7C7LhuhMMYZQUXh4r/GYSUC+yY7MD4OEtYVv0c 5bChjq/PmsC5hyClFsDMlEl9p0NQVdmP8tgEfmmvE/B4B1x/kofwhjgAx3oqBPxwW9f1Rpbe 7QyHe37pokldvz2wqsmOp12hcrwI52hIbYWDs9s5GtXBdNU9lKeFMP6WiN/eBXPaKzdjW3o1 +joM1A4X6I+aBmCKZgpJBZY5/8PyAVACMzZSHhrAyu2l7CVbuSRUHikNsL0QFloLdN+pc639 eyNY0pxXA4oEYmOhwQEPPxEuiZLHhKoBJFGxqdCtu9NXJPSXxFxmZWF+ssgQVq4GFiQmNhM6 FEyfFVEBkgg2mGXDWdmGipCG5rHA6W6uV3b3aqpFz1HjY2ara0muJcL5tvJccYZDAHoq7jjS fKXQTvowc/dk5bafiE9fcoZNl/2Zoh9NRwgvT2rOuqorMc3SUaN0t4k+4UmZtqUh1YxrIzF9 cch7ZLqZwE9bya47edfk9yb4vjCY0eJlXqzhVPzVw44DVhHBnf2NYkweKLG3RmVyyV+FKjyT SgMAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprOIsWRmVeSWpSXmKPExsVy+t/xu7qdTkHxBtuWGlr0njvJZLFxxnpW i//bJjJbXPn6ns1i5eqjTBYL9ltbfLnykMli0+NrrBZvjhxjtLi8aw6bxdojd9ktDn54wmqx utPRgddjzbw1jB57vy1g8dj+7QGrx/3u40wem5fUe9z+95jZY/KN5Yweu282sHn0bVnF6PF5 k5zHu/lv2QK4o/RsivJLS1IVMvKLS2yVog0tjPQMLS30jEws9QyNzWOtjEyV9O1sUlJzMstS i/TtEvQyXn78yVIwQbziz9JlTA2Mi4S7GDk5JARMJO496GDpYuTiEBJYyihxafJORoiEjMTJ aQ2sELawxJ9rXWwQRZ8YJdbfuMkOkmATMJToeguREBHoZJSY1v0RLMEs0Mwscf5lLYgtLBAo sW/eExYQm0VAVeLL7eVsIDavgJ3EyWcnWSA2yEus3nCAGcTmBIpvnfEEbLOQgK3EhzmLWSYw 8i1gZFjFKJJaWpybnltspFecmFtcmpeul5yfu4kRGCnbjv3csoOx613wIUYBDkYlHl4G+6B4 IdbEsuLK3EOMEhzMSiK8TmdPxwnxpiRWVqUW5ccXleakFh9iNAU6aiKzlGhyPjCK80riDU0N zS0sDc2NzY3NLJTEeTsEDsYICaQnlqRmp6YWpBbB9DFxcEo1MFruLvZg3Ccs3i5S2GqcorHO yXdiEXfnmqnz/m79Pt/lzpFjzj92cexXMF3pJfBhwtPm95vOBK+XjTBI1rRxr2bS0n1se7+j 8/NxtkWH9/AkGDLL2HQ1MB2ef3zdnFqvXul1fizZb6ebudhNvmfsGth969/lf26nlypkWbHo pk4PU2q+u+LASyWW4oxEQy3mouJEALruKeyqAgAA X-CMS-MailID: 20200904133505eucas1p2de5392a85883aca8e7774735811eb4c8 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20200904133505eucas1p2de5392a85883aca8e7774735811eb4c8 X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20200904133505eucas1p2de5392a85883aca8e7774735811eb4c8 References: <20200904131711.12950-1-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 c7f10b2c93d2..13c31e2d7254 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