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 CEF5DC433E6 for ; Tue, 1 Sep 2020 18:42:43 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id AA0192078B for ; Tue, 1 Sep 2020 18:42:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AA0192078B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id 92F6B8666C; Tue, 1 Sep 2020 18:42:43 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 692lCHCEQHGB; Tue, 1 Sep 2020 18:42:42 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by fraxinus.osuosl.org (Postfix) with ESMTP id DAC9786652; Tue, 1 Sep 2020 18:42:42 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id BCB4FC088B; Tue, 1 Sep 2020 18:42:42 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id 50C4FC0052 for ; Tue, 1 Sep 2020 18:42:41 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id 14CCD274DB for ; Tue, 1 Sep 2020 18:42:41 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 8JZ4s1oQFrO5 for ; Tue, 1 Sep 2020 18:42:37 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by silver.osuosl.org (Postfix) with ESMTP id 9434620495 for ; Tue, 1 Sep 2020 18:42:37 +0000 (UTC) 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 272A71FB; Tue, 1 Sep 2020 11:42:37 -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 C9B773F71F; Tue, 1 Sep 2020 11:42:34 -0700 (PDT) Subject: Re: [PATCH v9 08/32] drm: i915: 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 References: <20200826063316.23486-1-m.szyprowski@samsung.com> <20200826063316.23486-9-m.szyprowski@samsung.com> From: Robin Murphy Message-ID: <38960f66-aab6-8615-9187-b85cf628a4fd@arm.com> Date: Tue, 1 Sep 2020 19:42:32 +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: <20200826063316.23486-9-m.szyprowski@samsung.com> Content-Language: en-GB Cc: Bartlomiej Zolnierkiewicz , David Airlie , intel-gfx@lists.freedesktop.org, Joonas Lahtinen , Jani Nikula , Daniel Vetter , Rodrigo Vivi , Christoph Hellwig , linux-arm-kernel@lists.infradead.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On 2020-08-26 07:32, 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. > > This driver creatively uses sg_table->orig_nents to store the size of the > allocated scatterlist and ignores the number of the entries returned by > dma_map_sg function. The sg_table->orig_nents is (mis)used to properly > free the (over)allocated scatterlist. > > This patch only introduces the common DMA-mapping wrappers operating > directly on the struct sg_table objects to the dmabuf related functions, > so the other drivers, which might share buffers with i915 could rely on > the properly set nents and orig_nents values. This one looks mechanical enough :) Reviewed-by: Robin Murphy > Signed-off-by: Marek Szyprowski > --- > drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 11 +++-------- > drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c | 7 +++---- > 2 files changed, 6 insertions(+), 12 deletions(-) > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c > index 2679380159fc..8a988592715b 100644 > --- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c > +++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c > @@ -48,12 +48,9 @@ static struct sg_table *i915_gem_map_dma_buf(struct dma_buf_attachment *attachme > src = sg_next(src); > } > > - if (!dma_map_sg_attrs(attachment->dev, > - st->sgl, st->nents, dir, > - DMA_ATTR_SKIP_CPU_SYNC)) { > - ret = -ENOMEM; > + ret = dma_map_sgtable(attachment->dev, st, dir, DMA_ATTR_SKIP_CPU_SYNC); > + if (ret) > goto err_free_sg; > - } > > return st; > > @@ -73,9 +70,7 @@ static void i915_gem_unmap_dma_buf(struct dma_buf_attachment *attachment, > { > struct drm_i915_gem_object *obj = dma_buf_to_obj(attachment->dmabuf); > > - dma_unmap_sg_attrs(attachment->dev, > - sg->sgl, sg->nents, dir, > - DMA_ATTR_SKIP_CPU_SYNC); > + dma_unmap_sgtable(attachment->dev, sg, dir, DMA_ATTR_SKIP_CPU_SYNC); > sg_free_table(sg); > kfree(sg); > > diff --git a/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c b/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c > index debaf7b18ab5..be30b27e2926 100644 > --- a/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c > +++ b/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c > @@ -28,10 +28,9 @@ static struct sg_table *mock_map_dma_buf(struct dma_buf_attachment *attachment, > sg = sg_next(sg); > } > > - if (!dma_map_sg(attachment->dev, st->sgl, st->nents, dir)) { > - err = -ENOMEM; > + err = dma_map_sgtable(attachment->dev, st, dir, 0); > + if (err) > goto err_st; > - } > > return st; > > @@ -46,7 +45,7 @@ static void mock_unmap_dma_buf(struct dma_buf_attachment *attachment, > struct sg_table *st, > enum dma_data_direction dir) > { > - dma_unmap_sg(attachment->dev, st->sgl, st->nents, dir); > + dma_unmap_sgtable(attachment->dev, st, dir, 0); > sg_free_table(st); > kfree(st); > } > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu