From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753511Ab1GZL2x (ORCPT ); Tue, 26 Jul 2011 07:28:53 -0400 Received: from merlin.infradead.org ([205.233.59.134]:54477 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753419Ab1GZL2o convert rfc822-to-8bit (ORCPT ); Tue, 26 Jul 2011 07:28:44 -0400 Subject: Re: [GIT PULL] core/printk changes for v3.1 From: Peter Zijlstra To: Arnaud Lacombe Cc: Ingo Molnar , Linus Torvalds , linux-kernel@vger.kernel.org, Thomas Gleixner , Andrew Morton , SergeySenozhatsky , DaveJones In-Reply-To: References: <20110722125934.GA25433@elte.hu> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Tue, 26 Jul 2011 13:28:17 +0200 Message-ID: <1311679697.24752.28.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2011-07-25 at 14:20 -0400, Arnaud Lacombe wrote: > > Peter Zijlstra (3): > > [...] > > lockdep: Fix trace_[soft,hard]irqs_[on,off]() recursion > > > This commit is triggering: > > WARNING: at /src/linux/linux/kernel/lockdep.c:2529 Not actually having reproduced the problem, does the below cure things? --- Subject: lockdep: Fix trace_hardirqs_on_caller() From: Peter Zijlstra Date: Tue Jul 26 13:13:44 CEST 2011 Commit dd4e5d3ac4a ("lockdep: Fix trace_[soft,hard]irqs_[on,off]() recursion") made a bit of a mess of the various checks and error conditions. In particular it moved the check for !irqs_disabled() before the spurious enable test, resulting in some warnings. Reported-by: Arnaud Lacombe Reported-by: Dave Jones Reported-by: Sergey Senozhatsky Signed-off-by: Peter Zijlstra --- kernel/lockdep.c | 30 ++++++++++++++++-------------- 1 file changed, 16 insertions(+), 14 deletions(-) Index: linux-2.6/kernel/lockdep.c =================================================================== --- linux-2.6.orig/kernel/lockdep.c +++ linux-2.6/kernel/lockdep.c @@ -2485,23 +2485,9 @@ static void __trace_hardirqs_on_caller(u { struct task_struct *curr = current; - if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled))) - return; - - if (unlikely(curr->hardirqs_enabled)) { - /* - * Neither irq nor preemption are disabled here - * so this is racy by nature but losing one hit - * in a stat is not a big deal. - */ - __debug_atomic_inc(redundant_hardirqs_on); - return; - } /* we'll do an OFF -> ON transition: */ curr->hardirqs_enabled = 1; - if (DEBUG_LOCKS_WARN_ON(current->hardirq_context)) - return; /* * We are going to turn hardirqs on, so set the * usage bit for all held locks: @@ -2529,9 +2515,25 @@ void trace_hardirqs_on_caller(unsigned l if (unlikely(!debug_locks || current->lockdep_recursion)) return; + if (unlikely(current->hardirqs_enabled)) { + /* + * Neither irq nor preemption are disabled here + * so this is racy by nature but losing one hit + * in a stat is not a big deal. + */ + __debug_atomic_inc(redundant_hardirqs_on); + return; + } + if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) return; + if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled))) + return; + + if (DEBUG_LOCKS_WARN_ON(current->hardirq_context)) + return; + current->lockdep_recursion = 1; __trace_hardirqs_on_caller(ip); current->lockdep_recursion = 0;