linux-kernel - Re: [PATCH v3 0/3] ACPI: container hot remove support.

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Message-ID: <50B4A2D5.2050603@huawei.com>
Date:	Tue, 27 Nov 2012 19:24:05 +0800
From:	Hanjun Guo <guohanjun@...wei.com>
To:	Tang Chen <tangchen@...fujitsu.com>
CC:	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, <yinghai@...nel.org>,
	<bhelgaas@...gle.com>, <lenb@...nel.org>, <jiang.liu@...wei.com>,
	<izumi.taku@...fujitsu.com>, <linux-acpi@...r.kernel.org>,
	<linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Wen Congyang <wency@...fujitsu.com>,
	Toshi Kani <toshi.kani@...com>
Subject: Re: [PATCH v3 0/3] ACPI: container hot remove support.

On 2012/11/27 10:38, Tang Chen wrote:
> On 11/27/2012 09:08 AM, Hanjun Guo wrote:
>> On 2012/11/26 14:06, Tang Chen wrote:
>>> On 11/26/2012 01:42 PM, Hanjun Guo wrote:
>>>>
>>>> Hi all,
>>>> I think Yasuaki mentioned the key point for the container device remove,
>>>> that is dependency.
>>>>
>>>> Currently, container, processor, and memory hotpulg are managed by different ACPI
>>>> hotplug drivers, the driver works when handle device hotplug individually, but they
>>>> have no idea for each other.
>>>>
>>>> This may introduce some issues, such as Yasuaki mentioned above, that is to say, we
>>>> should remove its child before remove the device itself, and hot add its parent before
>>>> the device itself.
>>>>
>>>> According to the ACPI namespace, we can resolve most of dependency issues. On a typical
>>>> two processor sockets system, the namespace is like this:
>>>>
>>>> /_SB                   ---container device, with HID ACPI0004
>>>>       |_SCK0             ---container device, with HID ACPI0004
>>>>        |_CPU0       ---processor device, with HID ACPI0009 or LNXCPU
>>>>             |_...
>>>>             |_CPUx
>>>>             |_MEM0       ---Memory device, with HID PNP0C80
>>>>       |_SCK1
>>>>        |_CPU0
>>>>             |_...
>>>>             |_CPUx
>>>>             |_MEM1
>>>>       |_PCI0            ---Host bridge, with HID PNP0A03 or PNP0A08
>>>>
>>>> If hot remove the container device, such as SCK0, we can easily know the dependency list
>>>> is CPU0~CPUx and MEM0, but I think the ACPI hotplug driver haven't resolve this now.
>>>>
>>>> And there is another corner case for hotplug devices in the namespace above, that is:
>>>> 1) Remove SCK0. yes, we can remove it with no dependency to the host bridge PCI0;
>>>>
>>>> 2) Remove SCK1 after SCK0. we should remove the host bridge PCI0 first,
>>>>      or the system will crash down. yes, dynamic dependency analysis is needed here.
>>>>      and the ACPI hotplug driver totally have no idea of this.
>>>>
>>>> so, should we do something to settle this down ?
>>>
>>> Hi Guo,
>>>
>>> I am trying to do this too. :)
>>
>> Great， what's your idea of this?
>>
> Hi Guo,
> 
> I noticed they had a lot of discussion on this topic.
> https://lkml.org/lkml/2012/11/15/159
> 
> And Vasilis's latest patches are here:
> https://lkml.org/lkml/2012/11/23/335
> 
> I think we can have a review of this patchset first. :)

Hi Tang,
Thanks for your remind, I will review Vasilis's latest patches,
and reply Vasilis's patch if I have any comments.

> 
> And also, as you said, the new ACPI hotplug framework from Liu Jiang
> will settle this problem more properly.
> So I think any solution now could be temporary. :)
> 
> .
> 


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