From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753662Ab2BCGMp (ORCPT ); Fri, 3 Feb 2012 01:12:45 -0500 Received: from relay3-d.mail.gandi.net ([217.70.183.195]:52331 "EHLO relay3-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753616Ab2BCGMo (ORCPT ); Fri, 3 Feb 2012 01:12:44 -0500 X-Originating-IP: 217.70.178.138 X-Originating-IP: 50.43.15.19 Date: Thu, 2 Feb 2012 22:12:25 -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 37/41] lockdep: Add CPU-idle/offline warning to lockdep-RCU splat Message-ID: <20120203061225.GD3008@leaf> References: <20120201194131.GA10028@linux.vnet.ibm.com> <1328125319-5205-1-git-send-email-paulmck@linux.vnet.ibm.com> <1328125319-5205-37-git-send-email-paulmck@linux.vnet.ibm.com> <20120202060752.GT29058@leaf> <20120202183007.GB2518@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120202183007.GB2518@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 Thu, Feb 02, 2012 at 10:30:07AM -0800, Paul E. McKenney wrote: > On Wed, Feb 01, 2012 at 10:07:52PM -0800, Josh Triplett wrote: > > On Wed, Feb 01, 2012 at 11:41:55AM -0800, Paul E. McKenney wrote: > > > --- a/kernel/lockdep.c > > > +++ b/kernel/lockdep.c > > > @@ -4176,7 +4176,13 @@ void lockdep_rcu_suspicious(const char *file, const int line, const char *s) > > > printk("-------------------------------\n"); > > > printk("%s:%d %s!\n", file, line, s); > > > printk("\nother info that might help us debug this:\n\n"); > > > - printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks); > > > + printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n", > > > + !rcu_lockdep_current_cpu_online() > > > + ? "RCU used illegally from offline CPU!\n" > > > + : rcu_is_cpu_idle() > > > + ? "RCU used illegally from idle CPU!\n" > > > + : "", > > > > Not the usual way I've seen chained ?: indented in kernel code: > > > > cond1 ? value1 : > > cond2 ? value2 : > > value3 > > > > That avoids repeated indentation over to the right, much like "else if". > > I tried the following, but didn't like it: > > !rcu_lockdep_current_cpu_online() ? "RCU used illegally from offline CPU!\n" : > rcu_is_cpu_idle() ? "RCU used illegally from idle CPU!\n" : > "", Seems like an improvement to me, but it also doesn't matter enough to bikeshed further about. :) - Josh Triplett