linux-kernel - Re: [PATCH] timekeeping: Limit system time to prevent 32-bit time

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Date:	Thu, 08 Oct 2015 10:52:05 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Miroslav Lichvar <mlichvar@...hat.com>
Cc:	linux-kernel@...r.kernel.org, y2038@...ts.linaro.org,
	John Stultz <john.stultz@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Prarit Bhargava <prarit@...hat.com>,
	Richard Cochran <richardcochran@...il.com>
Subject: Re: [PATCH] timekeeping: Limit system time to prevent 32-bit time_t overflow

On Thursday 08 October 2015 08:23:44 Miroslav Lichvar wrote:
> On Wed, Oct 07, 2015 at 05:10:34PM +0200, Arnd Bergmann wrote:
> > On Wednesday 07 October 2015 16:23:44 Miroslav Lichvar wrote:
> > > Without the limit added by this patch make will go nuts just one week
> > > later when the 32-bit time_t overflows to Dec 13 1901 and the files
> > > will appear as 136 years in the future. How is that better?
> > 
> > Not better or worse at all, that was my point. The time is still
> > wrong either way, whether you step back by a week or 136 years.
> 
> The difference is that with the one-week step the kernel and userspace
> still agree on the current time and it is always valid from the kernel
> point of view, absolute timers can be set, etc.

Ok, I can see that as an improvement, but it still seems to give
a false sense of safety, and I feel we really should not have any code
rely on this behavior.

	Arnd
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