From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.linuxfoundation.org ([140.211.169.12]:46808 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S23993913AbdAKUg0zfcB1 (ORCPT ); Wed, 11 Jan 2017 21:36:26 +0100 Date: Wed, 11 Jan 2017 21:31:00 +0100 From: "gregkh@linuxfoundation.org" Subject: Re: [PATCH 2/9] Move dma_ops from archdata into struct device Message-ID: <20170111203100.GB17895@kroah.com> References: <20170111005648.14988-1-bart.vanassche@sandisk.com> <20170111005648.14988-3-bart.vanassche@sandisk.com> <20170111064803.GB26893@kroah.com> <1484158589.2619.14.camel@sandisk.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1484158589.2619.14.camel@sandisk.com> Return-Path: Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-subscribe: List-owner: List-post: List-archive: To: Bart Van Assche Cc: "linux-parisc@vger.kernel.org" , "linux-pci@vger.kernel.org" , "ysato@users.sourceforge.jp" , "linux-xtensa@linux-xtensa.org" , "linux-rdma@vger.kernel.org" , "jesper.nilsson@axis.com" , "mulix@mulix.org" , "hpa@zytor.com" , "catalin.marinas@arm.com" , "uclinux-h8-devel@lists.sourceforge.jp" , "linux-hexagon@vger.kernel.org" , "geoff@infradead.org" , "jcmvbkbc@gmail.com" , "linux@armlinux.org.uk" , "iommu@lists.linux-foundation.org" , "linux-c6x-dev@linux-c6x.org" , "linux-am33-list@redhat.com" , "linux-ia64@vger.kernel.org" , "linux-cris-kernel@axis.com" , "linux-mips@linux-mips.org" , "linux-m68k@lists.linux-m68k.org" , "a-jacquiot@ti.com" , "dalias@libc.org" , "linux-metag@vger.kernel.org" , "nios2-dev@lists.rocketboards.org" , "linux-sh@vger.kernel.org" , "shorne@gmail.com" , "lftan@altera.com" , "deller@gmx.de" , "jdmason@kudzu.us" , "linux-alpha@vger.kernel.org" , "openrisc@lists.librecores.org" , "sparclinux@vger.kernel.org" , "chris@zankel.net" , "davem@davemloft.net" , "joro@8bytes.org" , "tglx@linutronix.de" , "linuxppc-dev@lists.ozlabs.org" , "x86@kernel.org" , "fenghua.yu@intel.com" , "jejb@parisc-linux.org" , "linux-snps-arc@lists.infradead.org" , "msalter@redhat.com" , "dledford@redhat.com" , "adi-buildroot-devel@lists.sourceforge.net" , "linux-arm-kernel@lists.infradead.org" , "starvik@axis.com" , "dhowells@redhat.com" , "hskinnemoen@gmail.com" , "mingo@redhat.com" , "stefan.kristiansson@saunalahti.fi" , "tony.luck@intel.com" , "linux-kernel@vger.kernel.org" , "jonas@southpole.se" , "geert@linux-m68k.org" , "egtvedt@samfundet.no" , "will.deacon@arm.com" , "linux-s390@vger.kernel.org" Message-ID: <20170111203100.WoStDX95UdVPxk7PbAz6WvStf2Ha48ZJaaAuYPmB_B0@z> On Wed, Jan 11, 2017 at 06:17:03PM +0000, Bart Van Assche wrote: > On Wed, 2017-01-11 at 07:48 +0100, Greg Kroah-Hartman wrote: > > On Tue, Jan 10, 2017 at 04:56:41PM -0800, Bart Van Assche wrote: > > > Several RDMA drivers, e.g. drivers/infiniband/hw/qib, use the CPU to > > > transfer data between memory and PCIe adapter. Because of performance > > > reasons it is important that the CPU cache is not flushed when such > > > drivers transfer data. Make this possible by allowing these drivers to > > > override the dma_map_ops pointer. Additionally, introduce the function > > > set_dma_ops() that will be used by a later patch in this series. > > > > When you say things like "additionally", that's a huge flag that this > > needs to be split up into multiple patches.  No need to add > > set_dma_ops() here in this patch. > > Hello Greg, > > Some architectures already define a set_dma_ops() function. So what this > patch does is to move both the dma_ops pointer and the set_dma_ops() > function from architecture-specific to architecture independent code. I > don't think that it is possible to separate these two changes. But I > understand that how I formulated the patch description caused confusion. I > will rewrite the patch description to make it more clear before I repost > this patch series. I think you should separate it out into multiple patches, this is a mess, as you say below: > > And I'd argue that it should be dma_ops_set(), and dma_ops_get(), just > > to keep the namespace sane, but that's probably a different set of > > patches... > > Every time I rebase and retest this patch series on top of a new kernel > version I have to modify some of the patches to compensate for changes in > the architecture code. So I expect that once Linus merges these patches that > he will have to resolve one or more merge conflicts. Including a rename of > the functions that query and set the dma_ops pointer in this patch series > would increase the number of merge conflicts triggered by this patch series > and would make Linus' job harder. So I hope that you will allow me to > postpone that rename until a later time ... That's a big sign that your patch series needs work. Break it up into smaller pieces, it should be possible, which will make merges easier (well, different in a way.) Good luck, tree-wide changes are not simple. greg k-h