linux-kernel - Re: [PATCH] timekeeping: Force upper bound for setting CLOCK

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Message-ID: <alpine.DEB.2.21.1903261329040.1789@nanos.tec.linutronix.de>
Date:   Tue, 26 Mar 2019 13:31:16 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Miroslav Lichvar <mlichvar@...hat.com>
cc:     LKML <linux-kernel@...r.kernel.org>,
        John Stultz <john.stultz@...aro.org>,
        Stephen Boyd <sboyd@...nel.org>, Arnd Bergmann <arnd@...db.de>,
        Richard Cochran <richardcochran@...il.com>,
        Hongbo Yao <yaohongbo@...wei.com>,
        Xiongfeng Wang <wangxiongfeng2@...wei.com>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH] timekeeping: Force upper bound for setting
 CLOCK_REALTIME

On Tue, 26 Mar 2019, Miroslav Lichvar wrote:
> On Sat, Mar 23, 2019 at 11:36:19AM +0100, Thomas Gleixner wrote:
> > It is reasonable to force an upper bound for the various methods of setting
> > CLOCK_REALTIME. Year 2262 is the absolute upper bound. Assume a maximum
> > uptime of 30 years which is plenty enough even for esoteric embedded
> > systems. That results in an upper bound of year 2232 for setting the time.
> 
> The patch looks good to me.
> 
> I like this approach better than using a larger value closer to the
> overflow (e.g. one week) and stepping the clock back automatically
> when the clock reaches that time, but I suspect it might possibly
> break more tests (or any unusual applications messing with time) as a
> much larger interval is now EINVAL.

I'm fine with breaking a few tests on the way rather than having undefined
behaviour and the constant flow of patches tackling the wrong end of the
stick.

Thanks,

	tglx