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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 77494C636CE for ; Fri, 16 Jul 2021 12:19:35 +0000 (UTC) Received: from smtp4.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 17E25613CF for ; Fri, 16 Jul 2021 12:19:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 17E25613CF Authentication-Results: mail.kernel.org; dmarc=fail (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 smtp4.osuosl.org (Postfix) with ESMTP id C59544149C; Fri, 16 Jul 2021 12:19:34 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id UiofMD46MLwn; Fri, 16 Jul 2021 12:19:33 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp4.osuosl.org (Postfix) with ESMTPS id 6D24F4045B; Fri, 16 Jul 2021 12:19:33 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 2A8B7C0010; Fri, 16 Jul 2021 12:19:33 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [IPv6:2605:bc80:3010::133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 8BB46C000E for ; Fri, 16 Jul 2021 12:19:32 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 6CA5A4016F for ; Fri, 16 Jul 2021 12:19:32 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 9LEaO8hemHeI for ; Fri, 16 Jul 2021 12:19:31 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp2.osuosl.org (Postfix) with ESMTP id C804140F1D for ; Fri, 16 Jul 2021 12:19:31 +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 08358D6E; Fri, 16 Jul 2021 05:19:31 -0700 (PDT) Received: from [10.57.36.240] (unknown [10.57.36.240]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BF0533F774; Fri, 16 Jul 2021 05:19:28 -0700 (PDT) Subject: Re: [PATCH v1 16/16] dma-mapping: Disallow .map_sg operations from returning zero on error To: Christoph Hellwig , Logan Gunthorpe References: <20210715164544.6827-1-logang@deltatee.com> <20210715164544.6827-17-logang@deltatee.com> <20210716063332.GD13345@lst.de> From: Robin Murphy Message-ID: <21b7f2f1-ccac-4567-6933-a258dcad7099@arm.com> Date: Fri, 16 Jul 2021 13:19:23 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210716063332.GD13345@lst.de> Content-Language: en-GB Cc: linux-s390@vger.kernel.org, linux-ia64@vger.kernel.org, linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org, Martin Oliveira , Stephen Bates , iommu@lists.linux-foundation.org, linux-alpha@vger.kernel.org, sparclinux@vger.kernel.org, xen-devel@lists.xenproject.org, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, 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 2021-07-16 07:33, Christoph Hellwig wrote: > On Thu, Jul 15, 2021 at 10:45:44AM -0600, Logan Gunthorpe wrote: >> @@ -194,6 +194,8 @@ static int __dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, >> else >> ents = ops->map_sg(dev, sg, nents, dir, attrs); >> >> + WARN_ON_ONCE(ents == 0); > > Turns this into a negative error code while we're at it, just to keep > the callers sane? Right, by this point returning the 0 would pass through dma_map_sg_attrs() OK, but AFAICS dma_map_sgtable() would now get confused and return success but with sgt->nents = 0. Coercing it to an error code (which dma_map_sg_attrs() would then just change right back) seems sensible for the sake of easy robustness. Robin. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu