Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754691AbcKUR06 (ORCPT ); Mon, 21 Nov 2016 12:26:58 -0500 Received: from mx2.suse.de ([195.135.220.15]:34668 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753586AbcKUR04 (ORCPT ); Mon, 21 Nov 2016 12:26:56 -0500 Date: Mon, 21 Nov 2016 09:26:47 -0800 From: Davidlohr Bueso To: Oleg Nesterov Cc: mingo@kernel.org, peterz@infradead.org, john.stultz@linaro.org, dimitrysh@google.com, linux-kernel@vger.kernel.org, Davidlohr Bueso Subject: Re: [PATCH 2/3] locking/percpu-rwsem: Replace bulky wait-queues with swait Message-ID: <20161121172647.GB31288@linux-80c1.suse> References: <1479495277-9075-1-git-send-email-dave@stgolabs.net> <1479495277-9075-3-git-send-email-dave@stgolabs.net> <20161121125535.GB1459@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20161121125535.GB1459@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 537 Lines: 17 On Mon, 21 Nov 2016, Oleg Nesterov wrote: >On 11/18, Davidlohr Bueso wrote: >> >> @@ -12,7 +12,7 @@ struct percpu_rw_semaphore { >> struct rcu_sync rss; >> unsigned int __percpu *read_count; >> struct rw_semaphore rw_sem; >> - wait_queue_head_t writer; >> + struct swait_queue_head writer; > >I won't argue, but even swait_queue_head is overkill in this case. > >We can just add "struct task_struct *writer" into percpu_rw_semaphore, Given that this is how all things locking/ work, I very much agree with you, lemme send a v2.