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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=uZfH/yW2EkwOl9gEcet4jN7ZXi9BLKHqqQrfr1sC6ac=; b=AtLxpFUgQ1gIsnUD05HWvo7d7Sxzi7DNP5aBvA5XQqGuYIMNyFn+vhOHZevg47GN3f V4eTpTm/kVnX9DW9K6Pa9XRprpozhN63O2DVY+H3KB98kthgAECeG8apXtgvUVvYRzYS RiH5Rh3tsvxZyYUa8GBPCY+u2439fO2fMPhtk9jc/8ErFOKJgIQpHzsvAt1R/KqJcqe8 5TVFGDDMqmTgd6wb1sSD9VjYedqdvUCHa+d7oqTulhT+i5PpvzrohtamG3bJdRWKwQ/2 YuqF51GK1fwoZX5b0vOW8BW1ok61aeZqARiuJQamUE3AYPcii2GM0Qb0IXAGHaNpLbvN rlxA== X-Gm-Message-State: AOAM531jybKfV0zlkYqGfjP7TEhrG/syrilqn6jrbh0PLEn7UUBdUreX d1Mmsu2R3X7k0xpti5lBDu0qtvhyVsBJHVnsgC8= X-Google-Smtp-Source: ABdhPJwYXjut1W+agJe7qHIAazerG/VY4Qh5rG0NKf6TSwEA+kmhHmC2ZVellCufA3F7oGA23ea+FfJqOJUfr5uzS0A= X-Received: by 2002:a05:600c:2255:: with SMTP id a21mr17035637wmm.67.1589765242888; Sun, 17 May 2020 18:27:22 -0700 (PDT) MIME-Version: 1.0 References: <20200513132114.6046-1-m.szyprowski@samsung.com> <20200513133245.6408-1-m.szyprowski@samsung.com> <20200513133245.6408-13-m.szyprowski@samsung.com> In-Reply-To: <20200513133245.6408-13-m.szyprowski@samsung.com> From: Qiang Yu Date: Mon, 18 May 2020 09:27:11 +0800 Message-ID: Subject: Re: [PATCH v5 13/38] drm: lima: fix common struct sg_table related issues To: Marek Szyprowski X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200517_182727_734771_5B67D0D3 X-CRM114-Status: GOOD ( 21.06 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: lima@lists.freedesktop.org, Bartlomiej Zolnierkiewicz , David Airlie , Linux Kernel Mailing List , dri-devel , linaro-mm-sig@lists.linaro.org, iommu@lists.linux-foundation.org, Daniel Vetter , Robin Murphy , Christoph Hellwig , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Looks good for me, patch is: Reviewed-by: Qiang Yu Regards, Qiang On Wed, May 13, 2020 at 9:33 PM Marek Szyprowski wrote: > > 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 > --- > For more information, see '[PATCH v5 00/38] DRM: fix struct sg_table nents > vs. orig_nents misuse' thread: > https://lore.kernel.org/linux-iommu/20200513132114.6046-1-m.szyprowski@samsung.com/T/ > --- > drivers/gpu/drm/lima/lima_gem.c | 11 ++++++++--- > drivers/gpu/drm/lima/lima_vm.c | 5 ++--- > 2 files changed, 10 insertions(+), 6 deletions(-) > > diff --git a/drivers/gpu/drm/lima/lima_gem.c b/drivers/gpu/drm/lima/lima_gem.c > index 5404e0d..cda43f6 100644 > --- a/drivers/gpu/drm/lima/lima_gem.c > +++ b/drivers/gpu/drm/lima/lima_gem.c > @@ -69,8 +69,7 @@ int lima_heap_alloc(struct lima_bo *bo, struct lima_vm *vm) > return ret; > > if (bo->base.sgt) { > - dma_unmap_sg(dev, bo->base.sgt->sgl, > - bo->base.sgt->nents, DMA_BIDIRECTIONAL); > + dma_unmap_sgtable(dev, bo->base.sgt, DMA_BIDIRECTIONAL, 0); > sg_free_table(bo->base.sgt); > } else { > bo->base.sgt = kmalloc(sizeof(*bo->base.sgt), GFP_KERNEL); > @@ -80,7 +79,13 @@ int lima_heap_alloc(struct lima_bo *bo, struct lima_vm *vm) > } > } > > - dma_map_sg(dev, sgt.sgl, sgt.nents, DMA_BIDIRECTIONAL); > + ret = dma_map_sgtable(dev, &sgt, DMA_BIDIRECTIONAL, 0); > + if (ret) { > + sg_free_table(&sgt); > + kfree(bo->base.sgt); > + bo->base.sgt = NULL; > + return ret; > + } > > *bo->base.sgt = sgt; > > diff --git a/drivers/gpu/drm/lima/lima_vm.c b/drivers/gpu/drm/lima/lima_vm.c > index 5b92fb8..2b2739a 100644 > --- a/drivers/gpu/drm/lima/lima_vm.c > +++ b/drivers/gpu/drm/lima/lima_vm.c > @@ -124,7 +124,7 @@ int lima_vm_bo_add(struct lima_vm *vm, struct lima_bo *bo, bool create) > if (err) > goto err_out1; > > - for_each_sg_dma_page(bo->base.sgt->sgl, &sg_iter, bo->base.sgt->nents, 0) { > + for_each_sgtable_dma_page(bo->base.sgt, &sg_iter, 0) { > err = lima_vm_map_page(vm, sg_page_iter_dma_address(&sg_iter), > bo_va->node.start + offset); > if (err) > @@ -298,8 +298,7 @@ int lima_vm_map_bo(struct lima_vm *vm, struct lima_bo *bo, int pageoff) > mutex_lock(&vm->lock); > > base = bo_va->node.start + (pageoff << PAGE_SHIFT); > - for_each_sg_dma_page(bo->base.sgt->sgl, &sg_iter, > - bo->base.sgt->nents, pageoff) { > + for_each_sgtable_dma_page(bo->base.sgt, &sg_iter, pageoff) { > err = lima_vm_map_page(vm, sg_page_iter_dma_address(&sg_iter), > base + offset); > if (err) > -- > 1.9.1 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel