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=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 0B6FAC47E4B for ; Thu, 15 Jul 2021 16:53:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D8C866128D for ; Thu, 15 Jul 2021 16:53:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233944AbhGOQ4O (ORCPT ); Thu, 15 Jul 2021 12:56:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57988 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229695AbhGOQ4N (ORCPT ); Thu, 15 Jul 2021 12:56:13 -0400 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2F1E9C06175F; Thu, 15 Jul 2021 09:53:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=SHLau5Ake9xcwQGIQtYxnHJNJDrvOEPwwI40kAVcRog=; b=U8UTMSyF6jF6T0gR2j3D29bvs eItdcAl8yoYyPm0BOaqxfp0KAqwYLm3tCNGL3UOXkwf2YVG3YLDETqIWI2+TSILpWhKSi+ZfIepQo lLen0o6KgjL85hkzakJ1QZk21sjlzGaASbY+nCfE7vBnPME0Mzb+H5RRmAZ+ZNIKuXcRPERLyqXtq VdtZCLk1naymemWuZBuS7BxTMY7tagmEv9JEUS6/HzNAPZKSxBYrlmfrzjhaGexuK2It2kZa4r1/A CGDiaLgNp8Hmc8kCrs/WvG5KWvG0MHFhzYQbO2P7Gy0lVzLUmA2kl6R0xkg6NYiRgFN4tL0/sUnPU SpUuGxGOA==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:46188) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1m44bq-00015M-DY; Thu, 15 Jul 2021 17:53:14 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1m44bl-0002LK-Cz; Thu, 15 Jul 2021 17:53:09 +0100 Date: Thu, 15 Jul 2021 17:53:09 +0100 From: "Russell King (Oracle)" To: Logan Gunthorpe Cc: linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, iommu@lists.linux-foundation.org, linux-parisc@vger.kernel.org, xen-devel@lists.xenproject.org, Christoph Hellwig , Marek Szyprowski , Robin Murphy , Stephen Bates , Martin Oliveira Subject: Re: [PATCH v1 00/16] .map_sg() error cleanup Message-ID: <20210715165309.GO22278@shell.armlinux.org.uk> References: <20210715164544.6827-1-logang@deltatee.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210715164544.6827-1-logang@deltatee.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: Russell King (Oracle) Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Thu, Jul 15, 2021 at 10:45:28AM -0600, Logan Gunthorpe wrote: > Hi, > > This series is spun out and expanded from my work to add P2PDMA support > to DMA map operations[1]. > > The P2PDMA work requires distinguishing different error conditions in > a map_sg operation. dma_map_sgtable() already allows for returning an > error code (where as dma_map_sg() is only allowed to return zero) > however, it currently only returns -EINVAL when a .map_sg() call returns > zero. > > This series cleans up all .map_sg() implementations to return appropriate > error codes. After the cleanup, dma_map_sg() will still return zero, > however dma_map_sgtable() will pass the error code from the .map_sg() > call. Thanks go to Martn Oliveira for doing a lot of the cleanup of the > obscure implementations. > > The patch set is based off of v5.14-rc1 and a git repo can be found > here: Have all the callers for dma_map_sg() been updated to check for error codes? If not, isn't that a pre-requisit to this patch set? >From what I see in Linus' current tree, we still have cases today where the return value of dma_map_sg() is compared with zero to detect failure, so I think that needs fixing before we start changing the dma_map_sg() implementation to return negative numbers. I also notice that there are various places that don't check the return value - and returning a negative number instead of zero may well cause random other bits to be set in fields. So, I think there's a fair amount of work to do in all the drivers before this change can be considered. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!