From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752851Ab1FGMDS (ORCPT ); Tue, 7 Jun 2011 08:03:18 -0400 Received: from hera.kernel.org ([140.211.167.34]:52942 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751147Ab1FGMDR (ORCPT ); Tue, 7 Jun 2011 08:03:17 -0400 Date: Tue, 7 Jun 2011 12:02:29 GMT From: tip-bot for Peter Zijlstra Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, torvalds@linux-foundation.org, a.p.zijlstra@chello.nl, lists@die-jansens.de, stable@kernel.org, tglx@linutronix.de, mingo@elte.hu Reply-To: lists@die-jansens.de, mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, torvalds@linux-foundation.org, stable@kernel.org, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <1307398759.2497.966.camel@laptop> References: <1307398759.2497.966.camel@laptop> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/urgent] lockdep: Fix lock_is_held() on recursion Git-Commit-ID: f2513cde93f0957d5dc6c09bc24b0cccd27d8e1d X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Tue, 07 Jun 2011 12:02:32 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: f2513cde93f0957d5dc6c09bc24b0cccd27d8e1d Gitweb: http://git.kernel.org/tip/f2513cde93f0957d5dc6c09bc24b0cccd27d8e1d Author: Peter Zijlstra AuthorDate: Mon, 6 Jun 2011 12:32:43 +0200 Committer: Ingo Molnar CommitDate: Tue, 7 Jun 2011 12:25:50 +0200 lockdep: Fix lock_is_held() on recursion 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 Cc: Link: http://lkml.kernel.org/r/1307398759.2497.966.camel@laptop Signed-off-by: Ingo Molnar --- kernel/lockdep.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 63437d0..298c927 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -3426,7 +3426,7 @@ int lock_is_held(struct lockdep_map *lock) 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);