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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 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) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-s390@vger.kernel.org, linux-ia64@vger.kernel.org, linux-parisc@vger.kernel.org, Robin Murphy , Martin Oliveira , linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, linux-alpha@vger.kernel.org, sparclinux@vger.kernel.org, xen-devel@lists.xenproject.org, Stephen Bates , linuxppc-dev@lists.ozlabs.org, Christoph Hellwig , linux-arm-kernel@lists.infradead.org, Marek Szyprowski Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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!