From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754351Ab3LRKeE (ORCPT ); Wed, 18 Dec 2013 05:34:04 -0500 Received: from terminus.zytor.com ([198.137.202.10]:44784 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754303Ab3LRKeA (ORCPT ); Wed, 18 Dec 2013 05:34:00 -0500 Date: Wed, 18 Dec 2013 02:33:27 -0800 From: tip-bot for Chuansheng Liu Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, torvalds@linux-foundation.org, peterz@infradead.org, paulmck@linux.vnet.ibm.com, akpm@linux-foundation.org, tglx@linutronix.de, chuansheng.liu@intel.com Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, peterz@infradead.org, paulmck@linux.vnet.ibm.com, akpm@linux-foundation.org, tglx@linutronix.de, chuansheng.liu@intel.com In-Reply-To: <1386136693.3650.48.camel@cliu38-desktop-build> References: <1386136693.3650.48.camel@cliu38-desktop-build> To: linux-tip-commits@vger.kernel.org Subject: [tip:core/locking] mutexes: Give more informative mutex warning in the !lock->owner case Git-Commit-ID: 91f30a17024ff0d8345e11228af33ee938b13426 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.1 (terminus.zytor.com [127.0.0.1]); Wed, 18 Dec 2013 02:33:32 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 91f30a17024ff0d8345e11228af33ee938b13426 Gitweb: http://git.kernel.org/tip/91f30a17024ff0d8345e11228af33ee938b13426 Author: Chuansheng Liu AuthorDate: Wed, 4 Dec 2013 13:58:13 +0800 Committer: Ingo Molnar CommitDate: Tue, 17 Dec 2013 15:35:10 +0100 mutexes: Give more informative mutex warning in the !lock->owner case When mutex debugging is enabled and an imbalanced mutex_unlock() is called, we get the following, slightly confusing warning: [ 364.208284] DEBUG_LOCKS_WARN_ON(lock->owner != current) But in that case the warning is due to an imbalanced mutex_unlock() call, and the lock->owner is NULL - so the message is misleading. So improve the message by testing for this case specifically: DEBUG_LOCKS_WARN_ON(!lock->owner) Signed-off-by: Liu, Chuansheng Signed-off-by: Peter Zijlstra Cc: Linus Torvalds Cc: Andrew Morton Cc: Thomas Gleixner Cc: Paul E. McKenney Link: http://lkml.kernel.org/r/1386136693.3650.48.camel@cliu38-desktop-build [ Improved the changelog, changed the patch to use !lock->owner consistently. ] Signed-off-by: Ingo Molnar --- kernel/locking/mutex-debug.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/kernel/locking/mutex-debug.c b/kernel/locking/mutex-debug.c index 7e3443f..faf6f5b 100644 --- a/kernel/locking/mutex-debug.c +++ b/kernel/locking/mutex-debug.c @@ -75,7 +75,12 @@ void debug_mutex_unlock(struct mutex *lock) return; DEBUG_LOCKS_WARN_ON(lock->magic != lock); - DEBUG_LOCKS_WARN_ON(lock->owner != current); + + if (!lock->owner) + DEBUG_LOCKS_WARN_ON(!lock->owner); + else + DEBUG_LOCKS_WARN_ON(lock->owner != current); + DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next); mutex_clear_owner(lock); }