Message-ID: <1340106888.6871.20.camel@deadeye.wl.decadent.org.uk>
Subject: Re: [PATCH -stable]  ntp: Correct TAI offset during leap second
From: Ben Hutchings <ben@decadent.org.uk>
To: Richard Cochran <richardcochran@gmail.com>
Cc: Jonathan Nieder <jrnieder@gmail.com>, John Stultz <johnstul@us.ibm.com>,
        stable@vger.kernel.org, Sasha Levin <levinsasha928@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>, Dave Jones <davej@redhat.com>,
        lkml <linux-kernel@vger.kernel.org>
Date: Tue, 19 Jun 2012 12:54:48 +0100
In-Reply-To: <20120618162854.GA3111@netboy.at.omicron.at>
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	 <20120617164751.GJ12429@burratino>
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On Mon, 2012-06-18 at 18:28 +0200, Richard Cochran wrote:
> On Mon, Jun 18, 2012 at 02:55:11PM +0100, Ben Hutchings wrote:
> > On Sun, 2012-06-17 at 19:34 +0200, Richard Cochran wrote:
> > > The offset should change upon entering state OOP, so something like
> > > the following (untested) patch should fix it for 3.2.9.
> > [...]
> >=20
> > It looks like this patch just changes the offset reported by adjtimex()
> > during an inserted second; is that right?
>=20
> Right, nothing really terrible will happen. The worst that I can
> imagine is that ntpd will set the new TAI offset during OOP, and then
> the kernel will add one to it, resulting in the TAI offset being off
> by one.
>=20
> But I really doubt any software makes use of this information.
>=20
> > Other than that, is 3.2.y likely to be OK?  Is there a good way to test
> > that in advance; does
> > <http://codemonkey.org.uk/2012/06/15/testing-leap-code/> look
> > reasonable?
>=20
> Well, if you want to wait all night then that is one way to do it.

I was intending to change the clock too...

> Here is a little test program I have been using:
>=20
>    https://github.com/richardcochran/leap

Thanks, that runs without incident but does show the incorrect offset
during OOP.

Ben.

--=20
Ben Hutchings
If more than one person is responsible for a bug, no one is at fault.

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