linux-kernel - Re: [PATCH 1/3] rtc: vr41xx: remove mktime usage

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Date:   Wed, 16 May 2018 15:55:00 +0200
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Alessandro Zummo <a.zummo@...ertech.it>, y2038@...ts.linaro.org,
        linux-rtc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] rtc: vr41xx: remove mktime usage

Hi,

On 20/04/2018 18:14:24+0200, Arnd Bergmann wrote:
> This driver uses mktime() and rtc_time_to_tm() to convert between time
> values. This works fine on 64-bit kernels over the whole supported
> range, and the vr41xx chip is a 64-bit MIPS implementation, but it is
> inconsistent because it doesn't do the same thing on 32-bit kernels that
> overflow in 2106 or 2038.
> 
> Changing it to use mktime64/rtc_time64_to_tm() should have no visible
> impact on vr41xx but gets us closer to removing the 32-bit interfaces.
> 
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  drivers/rtc/rtc-vr41xx.c | 24 ++++++++++++------------
>  1 file changed, 12 insertions(+), 12 deletions(-)
> 

I've applied the series a while ago. It should be noted that mktime64
will fail on 32bit platforms in year 21000 or so but I pretty sure it is
not worth fixing. My understanding is that the kernel will fail in April
2262 anyway as ktime_t will overflow.

Note that I will be following up with multiple series adding proper
rtc HW range, removing set_mmss and rtc_time_to_tm/rtc_tm_to_time64.

-- 
Alexandre Belloni, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com