linux-kernel - Re: [PATCH V2] MIPS: Fix poweroff failure when HOTPLUG

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Message-ID: <CAJiQ=7DGRxHp2hv79xpBdB_gV=iTiQaap=aytMe8=cNcm29Vrg@mail.gmail.com>
Date:	Sat, 18 Aug 2012 10:50:20 -0700
From:	Kevin Cernekee <cernekee@...il.com>
To:	Linux MIPS Mailing List <linux-mips@...ux-mips.org>,
	Ralf Baechle <ralf@...ux-mips.org>
Cc:	linux-kernel@...r.kernel.org, Fuxin Zhang <zhangfx@...ote.com>,
	Zhangjin Wu <wuzhangjin@...il.com>,
	Hongliang Tao <taohl@...ote.com>, Hua Yan <yanh@...ote.com>,
	Yong Zhang <yong.zhang@...driver.com>, stable@...r.kernel.org
Subject: Re: [PATCH V2] MIPS: Fix poweroff failure when HOTPLUG_CPU configured.

On Mon, Aug 13, 2012 at 5:52 AM, Huacai Chen <chenhc@...ote.com> wrote:
> When poweroff machine, kernel_power_off() call disable_nonboot_cpus().
> And if we have HOTPLUG_CPU configured, disable_nonboot_cpus() is not an
> empty function but attempt to actually disable the nonboot cpus. Since
> system state is SYSTEM_POWER_OFF, play_dead() won't be called and thus
> disable_nonboot_cpus() hangs. Therefore, we make this patch to avoid
> poweroff failure.

I have seen the same problem; sometimes it causes a kernel oops too.

>  #ifdef CONFIG_HOTPLUG_CPU
> -               if (!cpu_online(cpu) && !cpu_isset(cpu, cpu_callin_map) &&
> -                   (system_state == SYSTEM_RUNNING ||
> -                    system_state == SYSTEM_BOOTING))
> +               if (!cpu_online(cpu) && !cpu_isset(cpu, cpu_callin_map))
>                         play_dead();

This fix works for me.

Acked-by: Kevin Cernekee <cernekee@...il.com>

I do see SMP boot problems ("Attempted to kill the idle task!" panic)
on a 4-way box if the !cpu_isset() check is removed.
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