linux-kernel - RE: [PATCH v4 1/5] x86/init: Make get/set_rtc

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Message-ID: <BYAPR21MB1688F9640E9006C184EA481AD7969@BYAPR21MB1688.namprd21.prod.outlook.com>
Date:   Fri, 7 Apr 2023 17:38:30 +0000
From:   "Michael Kelley (LINUX)" <mikelley@...rosoft.com>
To:     Wei Liu <wei.liu@...nel.org>,
        Saurabh Sengar <ssengar@...ux.microsoft.com>
CC:     "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>, "hpa@...or.com" <hpa@...or.com>,
        KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Dexuan Cui <decui@...rosoft.com>,
        "arnd@...db.de" <arnd@...db.de>,
        Tianyu Lan <Tianyu.Lan@...rosoft.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        "jgross@...e.com" <jgross@...e.com>,
        "mat.jonczyk@...pl" <mat.jonczyk@...pl>
Subject: RE: [PATCH v4 1/5] x86/init: Make get/set_rtc_noop() public

From: Wei Liu <wei.liu@...nel.org> Sent: Friday, April 7, 2023 10:26 AM
> 
> On Tue, Apr 04, 2023 at 02:01:00AM -0700, Saurabh Sengar wrote:
> > Make get/set_rtc_noop() to be public so that they can be used
> > in other modules as well.
> >
> > Co-developed-by: Tianyu Lan <tiala@...rosoft.com>
> > Signed-off-by: Tianyu Lan <tiala@...rosoft.com>
> > Signed-off-by: Saurabh Sengar <ssengar@...ux.microsoft.com>
> > Reviewed-by: Wei Liu <wei.liu@...nel.org>
> > Reviewed-by: Michael Kelley <mikelley@...rosoft.com>
> > ---
> >  arch/x86/include/asm/x86_init.h | 2 ++
> >  arch/x86/kernel/x86_init.c      | 4 ++--
> >  2 files changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
> > index acc20ae4079d..88085f369ff6 100644
> > --- a/arch/x86/include/asm/x86_init.h
> > +++ b/arch/x86/include/asm/x86_init.h
> > @@ -330,5 +330,7 @@ extern void x86_init_uint_noop(unsigned int unused);
> >  extern bool bool_x86_init_noop(void);
> >  extern void x86_op_int_noop(int cpu);
> >  extern bool x86_pnpbios_disabled(void);
> > +extern int set_rtc_noop(const struct timespec64 *now);
> > +extern void get_rtc_noop(struct timespec64 *now);
> >
> >  #endif
> > diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
> > index 95be3831df73..d82f4fa2f1bf 100644
> > --- a/arch/x86/kernel/x86_init.c
> > +++ b/arch/x86/kernel/x86_init.c
> > @@ -33,8 +33,8 @@ static int __init iommu_init_noop(void) { return 0; }
> >  static void iommu_shutdown_noop(void) { }
> >  bool __init bool_x86_init_noop(void) { return false; }
> >  void x86_op_int_noop(int cpu) { }
> > -static __init int set_rtc_noop(const struct timespec64 *now) { return -EINVAL; }
> > -static __init void get_rtc_noop(struct timespec64 *now) { }
> > +int set_rtc_noop(const struct timespec64 *now) { return -EINVAL; }
> > +void get_rtc_noop(struct timespec64 *now) { }
> 
> I just had a second thought on this -- do you really need to drop the
> __init annotation for these two functions?
> 
> Thanks,
> Wei.

I think "yes".   In Patch 5 of the series, these are plugged into
x86_platform.get_wallclock() and set_wallclock().  The
x86_platform.get_wallclock() function can be called by
read_persistent_clock64(), which is not a __init function and
that may be called during resume from hibernation.

x86_platform.set_wallclock() is also called by a non __init function
update_persistent_clock64(), which is called by sync_hw_clock().

Michael

> 
> >
> >  static __initconst const struct of_device_id of_cmos_match[] = {
> >  	{ .compatible = "motorola,mc146818" },
> > --
> > 2.34.1
> >