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

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Date:   Tue, 13 Sep 2022 18:13:56 +0300
From:   Dmitry Osipenko <dmitry.osipenko@...labora.com>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        rafael.j.wysocki@...el.com, lenb@...nel.org
Cc:     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 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/

> +	 * 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