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Date:   Tue, 14 Aug 2012 13:48:56 +0200
From:   Ralf Baechle <ralf@linux-mips.org>
To:     Huacai Chen <chenhc@lemote.com>
Cc:     linux-mips@linux-mips.org, linux-kernel@vger.kernel.org,
        Fuxin Zhang <zhangfx@lemote.com>,
        Zhangjin Wu <wuzhangjin@gmail.com>,
        Hongliang Tao <taohl@lemote.com>, Hua Yan <yanh@lemote.com>,
        Yong Zhang <yong.zhang@windriver.com>, stable@vger.kernel.org
Subject: Re: [PATCH V2] MIPS: Fix poweroff failure when HOTPLUG_CPU
 configured.
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On Mon, Aug 13, 2012 at 08:52:24PM +0800, Huacai Chen 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.

> diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
> index e9a5fd7..69b17a9 100644
> --- a/arch/mips/kernel/process.c
> +++ b/arch/mips/kernel/process.c
> @@ -72,9 +72,7 @@ void __noreturn cpu_idle(void)
>  			}
>  		}
>  #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))

Looks good - but I'm wondering if the "!cpu_isset(cpu, cpu_callin_map)"
can be removed as well?

Also, which -stable branches is this patch applicable?

  Ralf