From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030900Ab0B0WxO (ORCPT ); Sat, 27 Feb 2010 17:53:14 -0500 Received: from e8.ny.us.ibm.com ([32.97.182.138]:34054 "EHLO e8.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965838Ab0B0WxL (ORCPT ); Sat, 27 Feb 2010 17:53:11 -0500 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, dvhltc@us.ibm.com, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 2/2] rcu: make task_subsys_state() RCU-lockdep checks handle boot-time use Date: Sat, 27 Feb 2010 14:53:08 -0800 Message-Id: <1267311188-16603-2-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.6.6 In-Reply-To: <20100227225240.GA16515@linux.vnet.ibm.com> References: <20100227225240.GA16515@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It is apparently legal to invoke task_subsys_state() without RCU protection during early boot time. After all, there are no concurrent tasks, so there can be no grace periods completing concurrently. But this does need an Acked-by from the cgroups folks. Located-by: Ingo Molnar Signed-off-by: Paul E. McKenney --- include/linux/cgroup.h | 1 + 1 files changed, 1 insertions(+), 0 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index c9bbcb2..a73e1ce 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -489,6 +489,7 @@ static inline struct cgroup_subsys_state *task_subsys_state( { return rcu_dereference_check(task->cgroups->subsys[subsys_id], rcu_read_lock_held() || + !rcu_scheduler_active || cgroup_lock_is_held()); } -- 1.6.6