From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.6 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BA049C433E7 for ; Tue, 1 Sep 2020 20:13:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A77372078B for ; Tue, 1 Sep 2020 20:13:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728675AbgIAUNf (ORCPT ); Tue, 1 Sep 2020 16:13:35 -0400 Received: from foss.arm.com ([217.140.110.172]:49476 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726323AbgIAUNe (ORCPT ); Tue, 1 Sep 2020 16:13:34 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id CCA181FB; Tue, 1 Sep 2020 13:13:33 -0700 (PDT) Received: from [10.57.40.122] (unknown [10.57.40.122]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8B1FE3F66F; Tue, 1 Sep 2020 13:13:31 -0700 (PDT) Subject: Re: [PATCH v9 24/32] drm: host1x: fix common struct sg_table related issues To: Marek Szyprowski , dri-devel@lists.freedesktop.org, iommu@lists.linux-foundation.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org Cc: Christoph Hellwig , Bartlomiej Zolnierkiewicz , linux-arm-kernel@lists.infradead.org, David Airlie , Daniel Vetter , Thierry Reding , linux-tegra@vger.kernel.org References: <20200826063316.23486-1-m.szyprowski@samsung.com> <20200826063316.23486-25-m.szyprowski@samsung.com> From: Robin Murphy Message-ID: Date: Tue, 1 Sep 2020 21:13:30 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20200826063316.23486-25-m.szyprowski@samsung.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-08-26 07:33, 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. Reviewed-by: Robin Murphy > Signed-off-by: Marek Szyprowski > --- > drivers/gpu/host1x/job.c | 22 ++++++++-------------- > 1 file changed, 8 insertions(+), 14 deletions(-) > > diff --git a/drivers/gpu/host1x/job.c b/drivers/gpu/host1x/job.c > index 89b6c14b7392..82d0a60ba3f7 100644 > --- a/drivers/gpu/host1x/job.c > +++ b/drivers/gpu/host1x/job.c > @@ -170,11 +170,9 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job) > goto unpin; > } > > - err = dma_map_sg(dev, sgt->sgl, sgt->nents, dir); > - if (!err) { > - err = -ENOMEM; > + err = dma_map_sgtable(dev, sgt, dir, 0); > + if (err) > goto unpin; > - } > > job->unpins[job->num_unpins].dev = dev; > job->unpins[job->num_unpins].dir = dir; > @@ -228,7 +226,7 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job) > } > > if (host->domain) { > - for_each_sg(sgt->sgl, sg, sgt->nents, j) > + for_each_sgtable_sg(sgt, sg, j) > gather_size += sg->length; > gather_size = iova_align(&host->iova, gather_size); > > @@ -240,9 +238,9 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job) > goto put; > } > > - err = iommu_map_sg(host->domain, > + err = iommu_map_sgtable(host->domain, > iova_dma_addr(&host->iova, alloc), > - sgt->sgl, sgt->nents, IOMMU_READ); > + sgt, IOMMU_READ); > if (err == 0) { > __free_iova(&host->iova, alloc); > err = -EINVAL; > @@ -252,12 +250,9 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job) > job->unpins[job->num_unpins].size = gather_size; > phys_addr = iova_dma_addr(&host->iova, alloc); > } else if (sgt) { > - err = dma_map_sg(host->dev, sgt->sgl, sgt->nents, > - DMA_TO_DEVICE); > - if (!err) { > - err = -ENOMEM; > + err = dma_map_sgtable(host->dev, sgt, DMA_TO_DEVICE, 0); > + if (err) > goto put; > - } > > job->unpins[job->num_unpins].dir = DMA_TO_DEVICE; > job->unpins[job->num_unpins].dev = host->dev; > @@ -660,8 +655,7 @@ void host1x_job_unpin(struct host1x_job *job) > } > > if (unpin->dev && sgt) > - dma_unmap_sg(unpin->dev, sgt->sgl, sgt->nents, > - unpin->dir); > + dma_unmap_sgtable(unpin->dev, sgt, unpin->dir, 0); > > host1x_bo_unpin(dev, unpin->bo, sgt); > host1x_bo_put(unpin->bo); >