From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751208Ab2BBFOG (ORCPT ); Thu, 2 Feb 2012 00:14:06 -0500 Received: from relay3-d.mail.gandi.net ([217.70.183.195]:59246 "EHLO relay3-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750797Ab2BBFOE (ORCPT ); Thu, 2 Feb 2012 00:14:04 -0500 X-Originating-IP: 217.70.178.133 X-Originating-IP: 50.43.15.19 Date: Wed, 1 Feb 2012 21:13:37 -0800 From: Josh Triplett To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, fweisbec@gmail.com, patches@linaro.org, "Paul E. McKenney" Subject: Re: [PATCH RFC tip/core/rcu 24/41] rcu: Check for idle-loop entry while in RCU read-side critical section Message-ID: <20120202051337.GP29058@leaf> References: <20120201194131.GA10028@linux.vnet.ibm.com> <1328125319-5205-1-git-send-email-paulmck@linux.vnet.ibm.com> <1328125319-5205-24-git-send-email-paulmck@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1328125319-5205-24-git-send-email-paulmck@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 01, 2012 at 11:41:42AM -0800, Paul E. McKenney wrote: > --- a/kernel/rcutree.c > +++ b/kernel/rcutree.c > @@ -366,6 +366,20 @@ static void rcu_idle_enter_common(struct rcu_dynticks *rdtp, long long oldval) > atomic_inc(&rdtp->dynticks); > smp_mb__after_atomic_inc(); /* Force ordering with next sojourn. */ > WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); > + > + /* > + * The idle task is not permitted to enter the idle loop while > + * in an RCU read-side critical section. > + */ > + rcu_lockdep_assert(!lock_is_held(&rcu_lock_map), > + "Illegal idle entry in RCU read-side " > + "critical section."); > + rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map), > + "Illegal idle entry in RCU-bh read-side " > + "critical section."); > + rcu_lockdep_assert(!lock_is_held(&rcu_sched_lock_map), > + "Illegal idle entry in RCU-sched read-side " > + "critical section."); Quoting a paragraph I added to Documentation/CodingStyle: > Statements longer than 80 columns will be broken into sensible chunks, unless > exceeding 80 columns significantly increases readability and does not hide > information. Descendants are always substantially shorter than the parent and > are placed substantially to the right. The same applies to function headers > with a long argument list. However, never break user-visible strings such as > printk messages, because that breaks the ability to grep for them. So, please don't break those strings across multiple lines. The same goes for the similar rcu_lockdep_assert strings added in a previous patch in this series. - Josh Triplett