From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752088AbcEKIoN (ORCPT ); Wed, 11 May 2016 04:44:13 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:37290 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751759AbcEKIoK (ORCPT ); Wed, 11 May 2016 04:44:10 -0400 Date: Wed, 11 May 2016 10:44:01 +0200 From: Peter Zijlstra To: Michal Hocko Cc: Tetsuo Handa , LKML , Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , "David S. Miller" , Tony Luck , Andrew Morton , Chris Zankel , Max Filippov , Davidlohr Bueso , Waiman Long Subject: Re: [PATCH 03/11] locking, rwsem: introduce basis for down_write_killable Message-ID: <20160511084401.GH3193@twins.programming.kicks-ass.net> References: <1459508695-14915-1-git-send-email-mhocko@kernel.org> <1459508695-14915-4-git-send-email-mhocko@kernel.org> <8bd03bdc-0373-a3bb-da12-045322efb797@I-love.SAKURA.ne.jp> <20160510115320.GJ23576@dhcp22.suse.cz> <20160510123806.GB3193@twins.programming.kicks-ass.net> <20160511072357.GC16677@dhcp22.suse.cz> <20160511082853.GF16677@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160511082853.GF16677@dhcp22.suse.cz> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 11, 2016 at 10:28:53AM +0200, Michal Hocko wrote: > Does the following look correct/reasonable? This is absolutely untested > and more for a discussion: I would much rather see it in common; something like so perhaps. --- kernel/locking/rwsem-xadd.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c index df4dcb883b50..5d7f2831a475 100644 --- a/kernel/locking/rwsem-xadd.c +++ b/kernel/locking/rwsem-xadd.c @@ -487,11 +487,9 @@ __rwsem_down_write_failed_common(struct rw_semaphore *sem, int state) /* Block until there are no active lockers. */ do { - if (signal_pending_state(state, current)) { - raw_spin_lock_irq(&sem->wait_lock); - ret = ERR_PTR(-EINTR); - goto out; - } + if (signal_pending_state(state, current)) + goto out_nolock; + schedule(); set_current_state(state); } while ((count = sem->count) & RWSEM_ACTIVE_MASK); @@ -504,6 +502,18 @@ __rwsem_down_write_failed_common(struct rw_semaphore *sem, int state) raw_spin_unlock_irq(&sem->wait_lock); return ret; + +out_nolock: + __set_current_state(TASK_RUNNING); + raw_spin_lock_irq(&sem->wait_lock); + list_del(&waiter.list); + if (list_empty(&sem->wait_list)) + rwsem_atomic_update(-RWSEM_WAITING_BIAS, sem); + else + __rwsem_do_wake(sem, RWSEM_WAKE_READERS); + raw_spin_unlock_irq(&sem->wait_lock); + + return ERR_PTR(-EINTR); } __visible struct rw_semaphore * __sched