From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1757160AbbE2UK0 (ORCPT <rfc822;w@1wt.eu>);
	Fri, 29 May 2015 16:10:26 -0400
Received: from mx1.redhat.com ([209.132.183.28]:37473 "EHLO mx1.redhat.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1756364AbbE2UKU (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Fri, 29 May 2015 16:10:20 -0400
Date: Fri, 29 May 2015 22:09:32 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: paulmck@linux.vnet.ibm.com, tj@kernel.org, mingo@redhat.com,
        linux-kernel@vger.kernel.org, der.herr@hofr.at, dave@stgolabs.net,
        torvalds@linux-foundation.org
Subject: Re: [RFC][PATCH 5/5] percpu-rwsem: Optimize readers and reduce
	global impact
Message-ID: <20150529200932.GA2516@redhat.com>
References: <20150526114356.609107918@infradead.org> <20150526120215.042527659@infradead.org> <20150529194534.GA31860@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20150529194534.GA31860@redhat.com>
User-Agent: Mutt/1.5.18 (2008-05-17)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 05/29, Oleg Nesterov wrote:
>
> Just one nit below,

Ah, wait, I forgot about the "trivial" percpu_up_write()...

Doesn't it need mb() before "state = readers_slow" to ensure
"release" semantics?

Oleg.