Message-id: <51D6B300.20804@renesas.com>
Date: Fri, 05 Jul 2013 20:50:24 +0900
From: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:17.0) Gecko/20130620
 Thunderbird/17.0.7
MIME-version: 1.0
To: tglx@linutronix.de
Cc: prarit@redhat.com, john.stultz@linaro.org,
        hiroyuki.yokoyama.vx@renesas.com, takashi.yoshii.zj@renesas.com,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: hrtimer: one more expiry time overflow check in hrtimer_interrupt
References: <51B6D4C4.9080400@renesas.com>
 <alpine.DEB.2.02.1306281416080.4013@ionos.tec.linutronix.de>
In-reply-to: <alpine.DEB.2.02.1306281416080.4013@ionos.tec.linutronix.de>
Content-type: text/plain; charset=ISO-8859-1
Content-transfer-encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1602
Lines: 38

On 6/28/2013 9:22 PM, Thomas Gleixner wrote:
>> On the other hand, we have another call site of tick_program_event() at
>> the bottom of hrtimer_interrupt().  The warning this time is triggered
>> there, so we need to apply the same fix to it.
> 
> Well, the problem is that you are just papering over the underlying
> issue of 32bit systems not being prepared for the year 2038 issue.
> 
> Just blindly silencing the warning is not going to make the system
> survive 2038 in any sane way. All timespec/val related time functions
> dealing with the clock realtime domain are simply broken in 2038 on
> 32bit, so it does not matter whether a warning triggers or not.

You're right.  With this patch applied, the hrtimer_interrupt /looks/
back to normal, but /proc/timer_list still show that "expires at [in
negative range]":

    active timers:
     #0: tick_cpu_sched, tick_sched_timer, S:01
     # expires at 50812500000-50812500000 nsecs [in -165398341280 to -165398341280 nsecs]

This shouldn't happen and something weird is still going on.

> We really need to tackle the underlying problem and not bandaiding a
> known to be broken system.

Agreed, but a little bit hard task for me.  This is 100% reproducible,
so I can help debug / verification.  Please let me know, if necessary.

Thanks for your comments,
--
Shinya Kuribayashi
Renesas Electronics
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/