linux-kernel - Re: [patch 6/8] ntp, rtc: Move rtc_set_ntp

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Message-ID: <20201209035155.GA1245199@piout.net>
Date:   Wed, 9 Dec 2020 04:51:55 +0100
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Jason Gunthorpe <jgg@...pe.ca>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>,
        Miroslav Lichvar <mlichvar@...hat.com>,
        John Stultz <john.stultz@...aro.org>,
        Prarit Bhargava <prarit@...hat.com>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        linux-rtc@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>
Subject: Re: [patch 6/8] ntp, rtc: Move rtc_set_ntp_time() to ntp code

On 07/12/2020 16:59:52-0400, Jason Gunthorpe wrote:
> On Sun, Dec 06, 2020 at 10:46:19PM +0100, Thomas Gleixner wrote:
> > rtc_set_ntp_time() is not really RTC functionality as the code is just a
> > user of RTC. Move it into the NTP code which allows further cleanups.
> > 
> > Requested-by: Alexandre Belloni <alexandre.belloni@...tlin.com>
> > Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> > ---
> >  drivers/rtc/Makefile  |    1 
> >  drivers/rtc/systohc.c |   61 ----------------------------------
> >  include/linux/rtc.h   |   34 -------------------
> >  kernel/time/ntp.c     |   88 ++++++++++++++++++++++++++++++++++++++++++++++++--
> >  4 files changed, 85 insertions(+), 99 deletions(-)
> 
> Fair enough, it is asymmetric with how HCTOSYS works, but not a big
> deal
> 

It is already asymmetric as hctosys will always happen as soon as the
rtc driver is loaded but systohc will only actually be called only if
ntp is enabled.

I must admit I did consider moving it ou of the rtc subsystem instead of
having it moved in class.c to solve the issue with rtc drivers compiled
as modules but I still carry the nasty BITS_PER_LONG check to keep
systemd happy on a 32bit userspace.

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com