From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757843AbZJFPT4 (ORCPT ); Tue, 6 Oct 2009 11:19:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757807AbZJFPTz (ORCPT ); Tue, 6 Oct 2009 11:19:55 -0400 Received: from tomts40.bellnexxia.net ([209.226.175.97]:56716 "EHLO tomts40-srv.bellnexxia.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757795AbZJFPTw (ORCPT ); Tue, 6 Oct 2009 11:19:52 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: ApsEAD75ykpMROOX/2dsb2JhbACBUdF6hCoE Date: Tue, 6 Oct 2009 11:19:14 -0400 From: Mathieu Desnoyers To: akpm@linux-foundation.org, Ingo Molnar , linux-kernel@vger.kernel.org, "Paul E. McKenney" Subject: Re: [patch 1/4] kernel call_rcu usage: initialize rcu_head structures (v2) Message-ID: <20091006151914.GB12530@Krystal> References: <20091006143727.868480435@polymtl.ca> <20091006144035.668169139@polymtl.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <20091006144035.668169139@polymtl.ca> X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.6.27.31-grsec (i686) X-Uptime: 11:17:57 up 49 days, 2:07, 2 users, load average: 0.06, 0.25, 0.22 User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Initialize rcu_head structures before passing them to call_rcu() to eliminate false positives in DEBUG_RCU_HEAD. Update: init at structure allocation time rather than just before calling call_rcu(). Ensures we do not void the debug race test. Signed-off-by: Mathieu Desnoyers CC: "Paul E. McKenney" CC: mingo@elte.hu CC: akpm@linux-foundation.org --- kernel/fork.c | 1 + kernel/pid.c | 1 + kernel/rcupdate.c | 1 + 3 files changed, 3 insertions(+) Index: linux-2.6-lttng/kernel/rcupdate.c =================================================================== --- linux-2.6-lttng.orig/kernel/rcupdate.c 2009-10-06 10:34:25.000000000 -0400 +++ linux-2.6-lttng/kernel/rcupdate.c 2009-10-06 11:17:16.000000000 -0400 @@ -90,6 +90,7 @@ void synchronize_rcu(void) if (rcu_blocking_is_gp()) return; + INIT_RCU_HEAD(&rcu.head); init_completion(&rcu.completion); /* Will wake me after RCU finished. */ call_rcu(&rcu.head, wakeme_after_rcu); Index: linux-2.6-lttng/kernel/pid.c =================================================================== --- linux-2.6-lttng.orig/kernel/pid.c 2009-10-06 10:34:25.000000000 -0400 +++ linux-2.6-lttng/kernel/pid.c 2009-10-06 11:12:46.000000000 -0400 @@ -264,6 +264,7 @@ struct pid *alloc_pid(struct pid_namespa get_pid_ns(ns); pid->level = ns->level; + INIT_RCU_HEAD(&pid->rcu); atomic_set(&pid->count, 1); for (type = 0; type < PIDTYPE_MAX; ++type) INIT_HLIST_HEAD(&pid->tasks[type]); Index: linux-2.6-lttng/kernel/fork.c =================================================================== --- linux-2.6-lttng.orig/kernel/fork.c 2009-10-06 11:11:10.000000000 -0400 +++ linux-2.6-lttng/kernel/fork.c 2009-10-06 11:11:54.000000000 -0400 @@ -1012,6 +1012,7 @@ static struct task_struct *copy_process( p->rcu_read_lock_nesting = 0; p->rcu_flipctr_idx = 0; #endif /* #ifdef CONFIG_PREEMPT_RCU */ + INIT_RCU_HEAD(&p->rcu); p->vfork_done = NULL; spin_lock_init(&p->alloc_lock); -- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68