From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757035Ab1FPHLS (ORCPT ); Thu, 16 Jun 2011 03:11:18 -0400 Received: from out4.smtp.messagingengine.com ([66.111.4.28]:57682 "EHLO out4.smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756974Ab1FPHLJ (ORCPT ); Thu, 16 Jun 2011 03:11:09 -0400 X-Sasl-enc: v98tNADuMLYH0p3Ks8HLb7re88753/uwVghExYS6Gmga 1308208268 X-Mailbox-Line: From gregkh@clark.kroah.org Wed Jun 15 17:29:10 2011 Message-Id: <20110616002909.937245351@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Wed, 15 Jun 2011 17:28:57 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Peter Zijlstra , Ingo Molnar Subject: [61/85] lockdep: Fix lock_is_held() on recursion In-Reply-To: <20110616002917.GA3627@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.33-longterm review patch. If anyone has any objections, please let us know. ------------------ From: Peter Zijlstra commit f2513cde93f0957d5dc6c09bc24b0cccd27d8e1d upstream. The main lock_is_held() user is lockdep_assert_held(), avoid false assertions in lockdep_off() sections by unconditionally reporting the lock is taken. [ the reason this is important is a lockdep_assert_held() in ttwu() which triggers a warning under lockdep_off() as in printk() which can trigger another wakeup and lock up due to spinlock recursion, as reported and heroically debugged by Arne Jansen ] Reported-and-tested-by: Arne Jansen Signed-off-by: Peter Zijlstra Cc: Linus Torvalds Link: http://lkml.kernel.org/r/1307398759.2497.966.camel@laptop Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- kernel/lockdep.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -3252,7 +3252,7 @@ int lock_is_held(struct lockdep_map *loc int ret = 0; if (unlikely(current->lockdep_recursion)) - return ret; + return 1; /* avoid false negative lockdep_assert_held() */ raw_local_irq_save(flags); check_flags(flags);