linux-kernel - Re: [PATCH 1/4] hotplug, x86: Fix online state in cpu0 debug interface

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Message-ID: <2432072.Zy8S4hcMML@vostro.rjw.lan>
Date:	Sun, 18 Aug 2013 02:59:35 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Toshi Kani <toshi.kani@...com>
Cc:	mingo@...hat.com, hpa@...ux.intel.com, tglx@...utronix.de,
	gregkh@...uxfoundation.org, benh@...nel.crashing.org,
	x86@...nel.org, linuxppc-dev@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org, fenghua.yu@...el.com, bp@...e.de,
	srivatsa.bhat@...ux.vnet.ibm.com, isimatu.yasuaki@...fujitsu.com
Subject: Re: [PATCH 1/4] hotplug, x86: Fix online state in cpu0 debug interface

On Saturday, August 17, 2013 01:46:56 PM Toshi Kani wrote:
> _debug_hotplug_cpu() is a debug interface that puts cpu0 offline during
> boot-up when CONFIG_DEBUG_HOTPLUG_CPU0 is set.  After cpu0 is put offline
> in this interface, however, /sys/devices/system/cpu/cpu0/online still
> shows 1 (online).
> 
> This patch fixes _debug_hotplug_cpu() to update dev->offline when CPU
> online/offline operation succeeded.
> 
> Signed-off-by: Toshi Kani <toshi.kani@...com>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

> ---
>  arch/x86/kernel/topology.c |    7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kernel/topology.c b/arch/x86/kernel/topology.c
> index 6e60b5f..5823bbd 100644
> --- a/arch/x86/kernel/topology.c
> +++ b/arch/x86/kernel/topology.c
> @@ -72,16 +72,19 @@ int __ref _debug_hotplug_cpu(int cpu, int action)
>  		ret = cpu_down(cpu);
>  		if (!ret) {
>  			pr_info("CPU %u is now offline\n", cpu);
> +			dev->offline = true;
>  			kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
>  		} else
>  			pr_debug("Can't offline CPU%d.\n", cpu);
>  		break;
>  	case 1:
>  		ret = cpu_up(cpu);
> -		if (!ret)
> +		if (!ret) {
> +			dev->offline = false;
>  			kobject_uevent(&dev->kobj, KOBJ_ONLINE);
> -		else
> +		} else {
>  			pr_debug("Can't online CPU%d.\n", cpu);
> +		}
>  		break;
>  	default:
>  		ret = -EINVAL;
> --
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-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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