Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756077Ab1DFRl6 (ORCPT ); Wed, 6 Apr 2011 13:41:58 -0400 Received: from e6.ny.us.ibm.com ([32.97.182.146]:35579 "EHLO e6.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755973Ab1DFRl4 (ORCPT ); Wed, 6 Apr 2011 13:41:56 -0400 Date: Wed, 6 Apr 2011 10:41:17 -0700 From: "Paul E. McKenney" To: Peter Zijlstra Cc: Lai Jiangshan , Michal Marek , "H. Peter Anvin" , Jan Beulich , Ingo Molnar , Alexander van Heukelum , Dipankar Sarma , Andrew Morton , Sam Ravnborg , David Howells , Oleg Nesterov , Roland McGrath , Serge Hallyn , linux-kernel@vger.kernel.org, Thomas Gleixner , Steven Rostedt Subject: Re: [RFC PATCH 4/5] RCU: Add TASK_RCU_OFFSET Message-ID: <20110406174117.GA5143@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <1301482656.4859.171.camel@twins> <4D931814.9090100@suse.cz> <4D93D29C.5010702@cn.fujitsu.com> <1301558691.2250.486.camel@laptop> <4D944E60.8080704@cn.fujitsu.com> <1301570320.4859.242.camel@twins> <4D953121.6090901@cn.fujitsu.com> <1301657749.4859.531.camel@twins> <20110405215450.GK2247@linux.vnet.ibm.com> <20110405230745.GA5972@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110405230745.GA5972@linux.vnet.ibm.com> User-Agent: Mutt/1.5.20 (2009-06-14) X-Content-Scanned: Fidelis XPS MAILER Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7266 Lines: 190 On Tue, Apr 05, 2011 at 04:07:45PM -0700, Paul E. McKenney wrote: > On Tue, Apr 05, 2011 at 02:54:50PM -0700, Paul E. McKenney wrote: > > On Fri, Apr 01, 2011 at 01:35:49PM +0200, Peter Zijlstra wrote: [ . . . ] > > > There isn't a single rcu_read_lock() user in the include chain of > > > sched.h, therefore its possible to split rcupdate.h such that one part > > > includes the bits needed for sched.h and another part that includes > > > sched.h and provides rcu_read_lock(). > > > > Yep, you can easily split struct rcu_head out into its own header file, > > and then include that into sched.h in place of rcupdate.h without trouble > > (at least in the few builds I tried). > > > > The trouble comes when you take the next step and include sched.h > > into include/linux/rcutree.h, which would be needed to allow > > TREE_PREEMPT_RCU's rcu_read_lock() and rcu_read_unlock() to be > > inlined. This pulls sched.h into files that it was not already > > included into, and we do get build failures (the first of which > > requires changes local to RCU, FWIW). > > > > Of course, it would be good to straighten this out. > > And here is a start -- the build is -much- quieter with this patch. > > The next layer on this onion is the use of the ctl_table typedef > in include/linux/key.h -- which is defined to be struct ctl_table. > Anyone know where struct ctl_table is defined? Color me blind, but I > am not seeing it... Sigh... In include/linux/sysctl.h, but with the opening brace on the next line. Anyway, the problem is that include/linux/sysctl.h and include/linux/key.h indirectly include each other in a mutually recursive fashion. So easy to fix -- just include include/linux/key.h prior to the include of include/linux/sysctl.h in kernel/sysctl_binary.c. Thanx, Paul > ------------------------------------------------------------------------ > > diff --git a/include/linux/rcu_head.h b/include/linux/rcu_head.h > new file mode 100644 > index 0000000..e0b8add > --- /dev/null > +++ b/include/linux/rcu_head.h > @@ -0,0 +1,46 @@ > +/* > + * Read-Copy Update mechanism for mutual exclusion: base structures > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License as published by > + * the Free Software Foundation; either version 2 of the License, or > + * (at your option) any later version. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + * > + * You should have received a copy of the GNU General Public License > + * along with this program; if not, write to the Free Software > + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. > + * > + * Copyright IBM Corporation, 2001 > + * > + * Author: Dipankar Sarma > + * > + * Based on the original work by Paul McKenney > + * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. > + * Papers: > + * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf > + * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001) > + * > + * For detailed explanation of Read-Copy Update mechanism see - > + * http://lse.sourceforge.net/locking/rcupdate.html > + * > + */ > + > +#ifndef __LINUX_RCU_HEAD_H > +#define __LINUX_RCU_HEAD_H > + > +/** > + * struct rcu_head - callback structure for use with RCU > + * @next: next update requests in a list > + * @func: actual update function to call after the grace period. > + */ > +struct rcu_head { > + struct rcu_head *next; > + void (*func)(struct rcu_head *head); > +}; > + > +#endif /* __LINUX_RCU_HEAD_H */ > diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h > index ff422d2..ab94fcfb 100644 > --- a/include/linux/rcupdate.h > +++ b/include/linux/rcupdate.h > @@ -52,15 +52,7 @@ extern int rcutorture_runnable; /* for sysctl */ > #define ULONG_CMP_GE(a, b) (ULONG_MAX / 2 >= (a) - (b)) > #define ULONG_CMP_LT(a, b) (ULONG_MAX / 2 < (a) - (b)) > > -/** > - * struct rcu_head - callback structure for use with RCU > - * @next: next update requests in a list > - * @func: actual update function to call after the grace period. > - */ > -struct rcu_head { > - struct rcu_head *next; > - void (*func)(struct rcu_head *head); > -}; > +#include > > /* Exported common interfaces */ > extern void call_rcu_sched(struct rcu_head *head, > @@ -141,14 +133,6 @@ static inline void rcu_exit_nohz(void) > > #endif /* #else #ifdef CONFIG_NO_HZ */ > > -#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU) > -#include > -#elif defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU) > -#include > -#else > -#error "Unknown RCU implementation specified to kernel configuration" > -#endif > - > /* > * init_rcu_head_on_stack()/destroy_rcu_head_on_stack() are needed for dynamic > * initialization and destruction of rcu_head on the stack. rcu_head structures > @@ -797,4 +781,12 @@ static inline void debug_rcu_head_unqueue(struct rcu_head *head) > } > #endif /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */ > > +#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU) > +#include > +#elif defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU) > +#include > +#else > +#error "Unknown RCU implementation specified to kernel configuration" > +#endif > + > #endif /* __LINUX_RCUPDATE_H */ > diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h > index 3a93348..c317eec 100644 > --- a/include/linux/rcutree.h > +++ b/include/linux/rcutree.h > @@ -30,6 +30,8 @@ > #ifndef __LINUX_RCUTREE_H > #define __LINUX_RCUTREE_H > > +#include > + > extern void rcu_init(void); > extern void rcu_note_context_switch(int cpu); > extern int rcu_needs_cpu(int cpu); > diff --git a/include/linux/sched.h b/include/linux/sched.h > index 83bd2e2..e7c6a90 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -78,7 +78,7 @@ struct sched_param { > #include > #include > #include > -#include > +#include > #include > #include > > @@ -2241,11 +2241,9 @@ int same_thread_group(struct task_struct *p1, struct task_struct *p2) > return p1->tgid == p2->tgid; > } > > -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) > > static inline int thread_group_empty(struct task_struct *p) > { -- 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/