From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755881Ab2EET1p (ORCPT ); Sat, 5 May 2012 15:27:45 -0400 Received: from e6.ny.us.ibm.com ([32.97.182.146]:54627 "EHLO e6.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752046Ab2EET1o (ORCPT ); Sat, 5 May 2012 15:27:44 -0400 Message-ID: <4FA57F2A.2090109@linaro.org> Date: Sat, 05 May 2012 12:27:38 -0700 From: John Stultz User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120329 Thunderbird/11.0.1 MIME-Version: 1.0 To: Richard Cochran CC: linux-kernel@vger.kernel.org, Thomas Gleixner Subject: Re: [PATCH 1/1] ntp: advertise correct TAI offset during leap second References: <7af92d6eabef55ddce07007ea515eda2e1474c52.1335442155.git.richardcochran@gmail.com> <4F9B1C55.50004@linaro.org> <20120428061718.GA2258@netboy.at.omicron.at> <4F9EEC86.8010201@linaro.org> <20120501061605.GC2243@netboy.at.omicron.at> <20120505100259.GA8294@netboy.at.omicron.at> In-Reply-To: <20120505100259.GA8294@netboy.at.omicron.at> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12050519-1976-0000-0000-00000CF19A53 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/05/2012 03:02 AM, Richard Cochran wrote: > On Tue, May 01, 2012 at 08:16:05AM +0200, Richard Cochran wrote: >> On Mon, Apr 30, 2012 at 12:48:22PM -0700, John Stultz wrote: >>> On 04/27/2012 11:17 PM, Richard Cochran wrote: >>>> Wait a minute. If user space manages this variable, then shouldn't the >>>> kernel leave it alone? >>> Right. That's why I'm asking. I actually haven't spent much time >>> looking at how the tai value provided via adjtimex is handled, and I >>> want to make sure its ok if we modify it from the kernel. >> We *are* already modifying it in kernel, but at the wrong time. >> >> I don't know either what ntpd does, but I will find out. >> >> [ But if ntpd just uses adjtimex() to use the kernel as storage for >> variables, then that is really stupid. ] > I took a look at ntp-4.2.6p5, and ntpd unconditionally sets the TAI > offset using MOD_TAI when it thinks the offset has changed. > > But I think it won't hurt if the kernel changes the offset > automatically, since ntpd will just try and set the same value again. Assuming that it doesn't happen right before the tick that adjusts the leapsecond. :) But that's a pre-existing bug and not a reason to block your patch that improves things. Thanks for the extra due-diligence here! thanks -john