Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752109Ab1DVHRc (ORCPT ); Fri, 22 Apr 2011 03:17:32 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:65173 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751746Ab1DVHRa (ORCPT ); Fri, 22 Apr 2011 03:17:30 -0400 Message-ID: <4DB12C1E.8050200@cn.fujitsu.com> Date: Fri, 22 Apr 2011 15:19:58 +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: <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> <4DA2709E.50902@cn.fujitsu.com> <20110411051241.GB18415@linux.vnet.ibm.com> <4DA2BC4E.4010000@cn.fujitsu.com> <20110411210223.GB2226@linux.vnet.ibm.com> In-Reply-To: <20110411210223.GB2226@linux.vnet.ibm.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-04-22 15:17:58, Serialize by Router on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-04-22 15:17:59, Serialize complete at 2011-04-22 15:17:59 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2639 Lines: 71 On 04/12/2011 05:02 AM, Paul E. McKenney wrote: > On Mon, Apr 11, 2011 at 04:31:10PM +0800, Lai Jiangshan wrote: >> On 04/11/2011 01:12 PM, Paul E. McKenney wrote: >> >>> -static inline struct task_struct *next_thread(const struct task_struct *p) >>> -{ >>> - return list_entry_rcu(p->thread_group.next, >>> - struct task_struct, thread_group); >>> -} >>> +/* Avoid #include hell for inlining rcu_read_lock(). */ >>> +#define next_thread(p) \ >>> + list_entry_rcu((p)->thread_group.next, struct task_struct, thread_group) >>> >> >> >> It is strange for me. >> The user of the API "next_thread(p)" must has two headers included, sched.h and rculist.h >> >> I know this is a very popular pattern of user space code, is it OK for kernel? >> I think a file(even a header file) uses API(Marco), it should includes the the corresponding >> headers, it reduces surprises(example, the name of "next_thread()" has no "rcu", >> it is not expected that rcuxxxx.h is required). >> >> I admit the work will become very much simpler if this pattern is allowed. > > The guy who maintains much of sched.h suggested it. ;-) > > Thanx, Paul > >> man fcntl: >> #include >> #include >> >> int fcntl(int fd, int cmd, ... /* arg */ ); >> -- >> 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/ > -- > 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/ > Hi, Paul What is the solution you prefer to? I insist on the solution which split rcupdate.h into 2 parts, the first part is rcupdate_defs.h which only contains: 1) struct rcu_head 2) MACRO rcu_dereference* 3) MACRO rcu_access_pointer rcu_access_index rcu_assign_pointer RCU_INIT_POINTER 4) rcu_*_lock_held() which is required by 2) All of these is required by sched.h, it is all about 450 lines of code. It does not just separate struct rcu_head out only, because rcu_dereference*() and APIs in rculist.h are required by in sched.h or headers included by sched.h. Any suggestion? Thanks, Lai -- 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/