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Date:   Tue, 6 Sep 2022 23:07:35 +0300
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Subject: Re: [PATCH v2] PM: ACPI: reboot: Reinstate S5 for reboot
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To:     Kai-Heng Feng <kai.heng.feng@canonical.com>,
        rafael.j.wysocki@intel.com
Cc:     Josef Bacik <josef@toxicpanda.com>,
        Dmitry Osipenko <dmitry.osipenko@collabora.com>,
        Petr Mladek <pmladek@suse.com>,
        Luis Chamberlain <mcgrof@kernel.org>,
        tangmeng <tangmeng@uniontech.com>,
        YueHaibing <yuehaibing@huawei.com>, linux-kernel@vger.kernel.org
References: <20220906143108.1749183-1-kai.heng.feng@canonical.com>
From:   Dmitry Osipenko <digetx@gmail.com>
In-Reply-To: <20220906143108.1749183-1-kai.heng.feng@canonical.com>
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06.09.2022 17:31, Kai-Heng Feng пишет:
> Commit d60cd06331a3 ("PM: ACPI: reboot: Use S5 for reboot") caused Dell
> PowerEdge r440 hangs at boot.
> 
> The issue is fixed by commit 2ca1c94ce0b6 ("tg3: Disable tg3 device on
> system reboot to avoid triggering AER"), so reinstate the patch again.
> 
> Cc: Josef Bacik <josef@toxicpanda.com>
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> ---
> v2:
>  - Use do_kernel_power_off_prepare() instead.
> 
>  kernel/reboot.c | 55 +++++++++++++++++++++++++------------------------
>  1 file changed, 28 insertions(+), 27 deletions(-)
> 
> diff --git a/kernel/reboot.c b/kernel/reboot.c
> index 3c35445bf5ad3..39cbb45afc54a 100644
> --- a/kernel/reboot.c
> +++ b/kernel/reboot.c
> @@ -243,28 +243,6 @@ void migrate_to_reboot_cpu(void)
>  	set_cpus_allowed_ptr(current, cpumask_of(cpu));
>  }
>  
> -/**
> - *	kernel_restart - reboot the system
> - *	@cmd: pointer to buffer containing command to execute for restart
> - *		or %NULL
> - *
> - *	Shutdown everything and perform a clean reboot.
> - *	This is not safe to call in interrupt context.
> - */
> -void kernel_restart(char *cmd)
> -{
> -	kernel_restart_prepare(cmd);
> -	migrate_to_reboot_cpu();
> -	syscore_shutdown();
> -	if (!cmd)
> -		pr_emerg("Restarting system\n");
> -	else
> -		pr_emerg("Restarting system with command '%s'\n", cmd);
> -	kmsg_dump(KMSG_DUMP_SHUTDOWN);
> -	machine_restart(cmd);
> -}
> -EXPORT_SYMBOL_GPL(kernel_restart);
> -
>  static void kernel_shutdown_prepare(enum system_states state)
>  {
>  	blocking_notifier_call_chain(&reboot_notifier_list,
> @@ -301,6 +279,34 @@ static BLOCKING_NOTIFIER_HEAD(power_off_prep_handler_list);
>   */
>  static ATOMIC_NOTIFIER_HEAD(power_off_handler_list);
>  
> +static void do_kernel_power_off_prepare(void)
> +{
> +	blocking_notifier_call_chain(&power_off_prep_handler_list, 0, NULL);
> +}
> +
> +/**
> + *	kernel_restart - reboot the system
> + *	@cmd: pointer to buffer containing command to execute for restart
> + *		or %NULL
> + *
> + *	Shutdown everything and perform a clean reboot.
> + *	This is not safe to call in interrupt context.
> + */
> +void kernel_restart(char *cmd)
> +{
> +	kernel_restart_prepare(cmd);
> +	do_kernel_power_off_prepare();

Looks like an abuse to me. Adding new SYS_OFF_MODE_RESTART_PREPARE and
updating acpi_sleep_init() to use it should be a better solution.