linux-kernel - Re: [PATCH v3 1/2] kernel/reboot: Add SYS_OFF_MODE_RESTART

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Date:   Fri, 16 Sep 2022 08:03:50 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Dmitry Osipenko <dmitry.osipenko@...labora.com>
Cc:     rafael.j.wysocki@...el.com, lenb@...nel.org,
        tangmeng <tangmeng@...ontech.com>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Petr Mladek <pmladek@...e.com>,
        YueHaibing <yuehaibing@...wei.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/2] kernel/reboot: Add SYS_OFF_MODE_RESTART_PREPARE mode

On Tue, Sep 13, 2022 at 11:14 PM Dmitry Osipenko
<dmitry.osipenko@...labora.com> wrote:
>
> On 9/13/22 09:20, Kai-Heng Feng wrote:
> > Add SYS_OFF_MODE_RESTART_PREPARE callbacks can be invoked before system
> > restart.
> >
> > This is a preparation for next patch.
> >
> > Suggested-by: Dmitry Osipenko <dmitry.osipenko@...labora.com>
> > Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> > ---
> > v3:
> >  - New patch.
> >
> >  include/linux/reboot.h |  8 ++++++++
> >  kernel/reboot.c        | 17 +++++++++++++++++
> >  2 files changed, 25 insertions(+)
> >
> > diff --git a/include/linux/reboot.h b/include/linux/reboot.h
> > index e5d9ef886179c..ba87cdef2335a 100644
> > --- a/include/linux/reboot.h
> > +++ b/include/linux/reboot.h
> > @@ -105,6 +105,14 @@ enum sys_off_mode {
> >        */
> >       SYS_OFF_MODE_POWER_OFF,
> >
> > +     /**
> > +      * @SYS_OFF_MODE_RESTART_PREPARE:
> > +      *
> > +      * Handlers prepare system to be powered off. Handlers are
>
> s/powered off/restarted/

Will address this in next revision.

Kai-Heng

>
> > +      * allowed to sleep.
> > +      */
> > +     SYS_OFF_MODE_RESTART_PREPARE,
> > +
> >       /**
> >        * @SYS_OFF_MODE_RESTART:
> >        *
> > diff --git a/kernel/reboot.c b/kernel/reboot.c
> > index 3c35445bf5ad3..3bba88c7ffc6b 100644
> > --- a/kernel/reboot.c
> > +++ b/kernel/reboot.c
> > @@ -243,6 +243,17 @@ void migrate_to_reboot_cpu(void)
> >       set_cpus_allowed_ptr(current, cpumask_of(cpu));
> >  }
> >
> > +/*
> > + *   Notifier list for kernel code which wants to be called
> > + *   to prepare system for restart.
> > + */
> > +static BLOCKING_NOTIFIER_HEAD(restart_prep_handler_list);
> > +
> > +static void do_kernel_restart_prepare(void)
> > +{
> > +     blocking_notifier_call_chain(&restart_prep_handler_list, 0, NULL);
> > +}
> > +
> >  /**
> >   *   kernel_restart - reboot the system
> >   *   @cmd: pointer to buffer containing command to execute for restart
> > @@ -254,6 +265,7 @@ void migrate_to_reboot_cpu(void)
> >  void kernel_restart(char *cmd)
> >  {
> >       kernel_restart_prepare(cmd);
> > +     do_kernel_restart_prepare();
> >       migrate_to_reboot_cpu();
> >       syscore_shutdown();
> >       if (!cmd)
> > @@ -396,6 +408,11 @@ register_sys_off_handler(enum sys_off_mode mode,
> >               handler->list = &power_off_handler_list;
> >               break;
> >
> > +     case SYS_OFF_MODE_RESTART_PREPARE:
> > +             handler->list = &restart_prep_handler_list;
> > +             handler->blocking = true;
> > +             break;
> > +
> >       case SYS_OFF_MODE_RESTART:
> >               handler->list = &restart_handler_list;
> >               break;
>
> With the above comment addressed:
>
> Reviewed-by: Dmitry Osipenko <dmitry.osipenko@...labora.com>
>
> --
> Best regards,
> Dmitry
>