From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751039AbaCLSop (ORCPT ); Wed, 12 Mar 2014 14:44:45 -0400 Received: from g4t3426.houston.hp.com ([15.201.208.54]:21060 "EHLO g4t3426.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750718AbaCLSon (ORCPT ); Wed, 12 Mar 2014 14:44:43 -0400 X-Greylist: delayed 98418 seconds by postgrey-1.27 at vger.kernel.org; Wed, 12 Mar 2014 14:44:43 EDT Message-ID: <1394649878.29352.21.camel@j-VirtualBox> Subject: Re: [tip:core/locking] locking/mutexes: Unlock the mutex without the wait_lock From: Jason Low To: Peter Zijlstra Cc: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, linux-tip-commits@vger.kernel.org Date: Wed, 12 Mar 2014 11:44:38 -0700 In-Reply-To: <20140312122442.GB27965@twins.programming.kicks-ass.net> References: <1390936396-3962-4-git-send-email-jason.low2@hp.com> <20140312122442.GB27965@twins.programming.kicks-ass.net> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2014-03-12 at 13:24 +0100, Peter Zijlstra wrote: > On Tue, Mar 11, 2014 at 05:41:23AM -0700, tip-bot for Jason Low wrote: > > kernel/locking/mutex.c | 8 ++++---- > > 1 file changed, 4 insertions(+), 4 deletions(-) > > > > diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c > > index 82dad2c..dc3d6f2 100644 > > --- a/kernel/locking/mutex.c > > +++ b/kernel/locking/mutex.c > > @@ -671,10 +671,6 @@ __mutex_unlock_common_slowpath(atomic_t *lock_count, int nested) > > struct mutex *lock = container_of(lock_count, struct mutex, count); > > unsigned long flags; > > > > - spin_lock_mutex(&lock->wait_lock, flags); > > - mutex_release(&lock->dep_map, nested, _RET_IP_); > > - debug_mutex_unlock(lock); > > - With the latest patch, perhaps it may be helpful to also add to the comment below, mentioning that it doesn't unlock here for debug mutexes since the following debug_mutex_unlock() would handle the unlocking instead. > > /* > > * some architectures leave the lock unlocked in the fastpath failure > > * case, others need to leave it locked. In the later case we have to > > @@ -683,6 +679,10 @@ __mutex_unlock_common_slowpath(atomic_t *lock_count, int nested) > > if (__mutex_slowpath_needs_to_unlock()) > >