Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753550Ab1DKDGR (ORCPT ); Sun, 10 Apr 2011 23:06:17 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:62381 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752138Ab1DKDGO convert rfc822-to-8bit (ORCPT ); Sun, 10 Apr 2011 23:06:14 -0400 Message-ID: <4DA2709E.50902@cn.fujitsu.com> Date: Mon, 11 Apr 2011 11:08:14 +0800 From: Lai Jiangshan User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.9) Gecko/20100921 Fedora/3.1.4-1.fc14 Thunderbird/3.1.4 MIME-Version: 1.0 To: paulmck@linux.vnet.ibm.com CC: "H. Peter Anvin" , Peter Zijlstra , Michal Marek , Jan Beulich , Ingo Molnar , Alexander van Heukelum , Dipankar Sarma , Andrew Morton , Sam Ravnborg , David Howells , Oleg Nesterov , Roland McGrath , linux-kernel@vger.kernel.org, Thomas Gleixner , Steven Rostedt Subject: Re: [RFC PATCH 4/5] RCU: Add TASK_RCU_OFFSET References: <1302077428.2225.1365.camel@twins> <20110406192119.GB2265@linux.vnet.ibm.com> <20110406201350.GA9378@linux.vnet.ibm.com> <1302123970.2207.4.camel@laptop> <4D9CDACB.9050705@linux.intel.com> <20110407003041.GD2265@linux.vnet.ibm.com> <4D9D507F.2040006@cn.fujitsu.com> <20110407154737.GF2262@linux.vnet.ibm.com> <20110407162600.GA24227@linux.vnet.ibm.com> <4D9E6438.5030206@cn.fujitsu.com> <20110408051359.GA2318@linux.vnet.ibm.com> In-Reply-To: <20110408051359.GA2318@linux.vnet.ibm.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-04-11 11:06:42, Serialize by Router on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-04-11 11:06:42 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5980 Lines: 128 On 04/08/2011 01:13 PM, Paul E. McKenney wrote: > On Fri, Apr 08, 2011 at 09:26:16AM +0800, Lai Jiangshan wrote: >> On 04/08/2011 12:26 AM, Paul E. McKenney wrote: >>> On Thu, Apr 07, 2011 at 08:47:37AM -0700, Paul E. McKenney wrote: >>>> On Thu, Apr 07, 2011 at 01:49:51PM +0800, Lai Jiangshan wrote: >>>>> On 04/07/2011 08:30 AM, Paul E. McKenney wrote: >>>>>> On Wed, Apr 06, 2011 at 02:27:39PM -0700, H. Peter Anvin wrote: >>>>>>> On 04/06/2011 02:06 PM, Peter Zijlstra wrote: >>>>>>>> On Wed, 2011-04-06 at 13:13 -0700, Paul E. McKenney wrote: >>>>>>>>> And the following patch builds correctly for defconfig x86 builds, >>>>>>>>> while allowing rcupdate.h to see the sched.h definitions as needed >>>>>>>>> to inline rcu_read_lock() and rcu_read_unlock(). >>>>>>>>> >>>>>>>> Looks like an entirely reasonable patch to me ;-) >>>>>>>> >>>>>>> >>>>>>> Quite... a lot better than the original proposal! >>>>>> >>>>>> Glad you both like it! >>>>>> >>>>>> When I do an allyesconfig build, I do get errors during the "CHECK" >>>>>> phase, when it is putting things into the usr/include in the build tree. >>>>>> I believe that this is because I am exposing different header files to >>>>>> the library-export scripts. The following patch silences some of them, >>>>>> but I am really out of my depth here. >>>>>> >>>>>> Sam, Jan, Michal, help? >>>>>> >>>>>> Thanx, Paul >>>>>> >>>>>> ------------------------------------------------------------------------ >>>>>> >>>>> >>>>> Easy to split rcupdate.h, hard to resolve the dependence problem. >>>>> >>>>> You can apply the next additional patch when you test: >>>> >>>> I am sure that you are quite correct. ;-) >>>> >>>> I am moving _rcu_read_lock() and _rcu_read_unlock() into >>>> include/linux/rcutree.h and include/linux/rcutiny.h, and I am sure that >>>> more pain will ensue. >>>> >>>> One thing I don't understand... How does is it helping to group the >>>> task_struct RCU-related fields into a structure? Is that generating >>>> better code on your platform due to smaller offsets or something? >> >> You don't like task_rcu_struct patch? I think it can make code clearer, >> and it can also check the code even when CONFIG_PREEMPT_RCU=n. >> >> For rcu_read_[un]lock(), it generates the same code, no better, no worse. >> >> It is just a cleanup patch, it is helpless for making rcu_read_[un]lock() inline, >> if you don't like it, I will give up it. > > I don't know that I feel strongly either way about it. It was necessary > with the integer-offset approach, but optional now. > >>>> Also, does your patchset address the CHECK warnings? >>> >>> I take it back... I applied the following patch on top of my earlier >>> one, and a defconfig x86 build completed without error. (Though I have >>> not tested the results of the build.) >>> >>> One possible difference -- I did this work on top of a recent Linus >>> git commit (b2a8b4b81966) rather than on top of my -rcu tree. Also, >>> I have not yet tried an allyesconfig build, which will no doubt locate >>> some more problems. >>> >>> Thanx, Paul >>> >> >> when defconfig or allyesconfig, CONFIG_PREEMPT=n and CONFIG_TREE_PREEMPT_RCU=n >> when you make them "y": >> >> In file included from include/linux/rcupdate.h:764:0, >> from include/linux/tracepoint.h:19, >> from include/linux/module.h:18, >> from include/linux/crypto.h:21, >> from arch/x86/kernel/asm-offsets.c:8: >> include/linux/rcutree.h:50:20: error: static declaration of ‘__rcu_read_lock’ follows non-static declaration >> include/linux/rcupdate.h:76:13: note: previous declaration of ‘__rcu_read_lock’ was here >> include/linux/rcutree.h:63:20: error: static declaration of ‘__rcu_read_unlock’ follows non-static declaration >> include/linux/rcupdate.h:77:13: note: previous declaration of ‘__rcu_read_unlock’ was here >> make[1]: *** [arch/x86/kernel/asm-offsets.s] Error 1 >> make: *** [prepare0] Error 2 > > Yep. I need to move the rcu_read_lock() APIs to follow the inclusion > of rcutree.h and rcutiny.h. Also add include of sched.h to rcutiny.h. > The code movement does bloat the patch a bit. But rcu_assign_pointer() > must precede the inclusion of rcutree.h and rcutiny.h, so it is not > possible to simply move the inclusions. See below. > > Thanx, Paul > sched.h still contains rcupdate.h after applied this patch. See my [PATCH 2/4] for more info. # make lib/is_single_threaded.o CHK include/linux/version.h CHK include/generated/utsrelease.h CALL scripts/checksyscalls.sh CC lib/is_single_threaded.o In file included from include/linux/rcupdate.h:639:0, from include/linux/rculist.h:10, from include/linux/sched.h:82, from lib/is_single_threaded.c:13: include/linux/rcutree.h: In function ‘__rcu_read_lock’: include/linux/rcutree.h:52:15: error: dereferencing pointer to incomplete type In file included from include/linux/rcupdate.h:639:0, from include/linux/rculist.h:10, from include/linux/sched.h:82, from lib/is_single_threaded.c:13: include/linux/rcutree.h: In function ‘__rcu_read_unlock’: include/linux/rcutree.h:68:5: error: dereferencing pointer to incomplete type include/linux/rcutree.h:70:7: error: dereferencing pointer to incomplete type include/linux/rcutree.h:71:46: error: dereferencing pointer to incomplete type include/linux/rcutree.h:71:78: error: dereferencing pointer to incomplete type include/linux/rcutree.h:71:6: warning: type defaults to ‘int’ in type name make[1]: *** [lib/is_single_threaded.o] Error 1 make: *** [lib/is_single_threaded.o] Error 2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/