linux-kernel - Re: [PATCH] X86/acpi: remove redundant logic of acpi memory hotadd

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Date:	Thu, 13 Dec 2012 10:36:38 +0800
From:	Jiang Liu <jiang.liu@...wei.com>
To:	"Liu, Jinsong" <jinsong.liu@...el.com>
CC:	Wen Congyang <wency@...fujitsu.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, Toshi Kani <toshi.kani@...com>,
	"Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
	"lenb@...nel.org" <lenb@...nel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Subject: Re: [PATCH] X86/acpi: remove redundant logic of acpi memory hotadd

On 2012-12-12 22:37, Liu, Jinsong wrote:
> Wen Congyang wrote:
>> At 12/08/2012 06:19 AM, Rafael J. Wysocki Wrote:
>>> On Tuesday, December 04, 2012 01:39:54 AM Liu, Jinsong wrote:
>>>> Resend it, add Rafael and linux-acpi@...r.kernel.org
>>>
>>> I wonder what memory hotplug people think about that.
>>>
>>> Thanks,
>>> Rafael
>>>
>>>
>>>> ===============
>>>> From 1d39279e45c54ce531691da5ffe261e7689dd92c Mon Sep 17 00:00:00
>>>> 2001 
>>>> From: Liu Jinsong <jinsong.liu@...el.com>
>>>> Date: Wed, 14 Nov 2012 18:52:06 +0800
>>>> Subject: [PATCH] X86/acpi: remove redundant logic of acpi memory
>>>> hotadd 
>>>>
>>>> When memory hotadd, acpi_memory_enable_device has already been done
>>>> at drv->ops.add (acpi_memory_device_add), no need to do it again
>>>> at notify callback.
>>>>
>>>> At acpi_memory_enable_device, acpi_memory_get_device_resources
>>>> is also a redundant action, since it has been done at drv->ops.add.
>>>>
>>>> Signed-off-by: Liu Jinsong <jinsong.liu@...el.com>
>>>> ---
>>>>  drivers/acpi/acpi_memhotplug.c |   17 -----------------
>>>>  1 files changed, 0 insertions(+), 17 deletions(-)
>>>>
>>>> diff --git a/drivers/acpi/acpi_memhotplug.c
>>>> b/drivers/acpi/acpi_memhotplug.c 
>>>> index 24c807f..a6489fd 100644
>>>> --- a/drivers/acpi/acpi_memhotplug.c
>>>> +++ b/drivers/acpi/acpi_memhotplug.c
>>>> @@ -220,15 +220,6 @@ static int acpi_memory_enable_device(struct
>>>>  	acpi_memory_device *mem_device) struct acpi_memory_info *info;
>>>>  	int node;
>>>>
>>>> -
>>>> -	/* Get the range from the _CRS */
>>>> -	result = acpi_memory_get_device_resources(mem_device);
>>>> -	if (result) {
>>>> -		printk(KERN_ERR PREFIX "get_device_resources failed\n");
>>>> -		mem_device->state = MEMORY_INVALID_STATE;
>>>> -		return result;
>>>> -	}
>>>> -
>>>>  	node = acpi_get_node(mem_device->device->handle);  	/*
>>>>  	 * Tell the VM there is more memory here...
>>>> @@ -357,14 +348,6 @@ static void
>>>>  		acpi_memory_device_notify(acpi_handle handle, u32 event, void
>>>> *data)  			break; } 
>>>>
>>>> -		if (acpi_memory_check_device(mem_device))
>>>> -			break;
>>
>> Hmm, if acpi_memory_check_device() fails, it means the memory device
>> disappears 
>> I don't know if a real hardware uses this way to remove memory device.
>>
>>>> -
>>>> -		if (acpi_memory_enable_device(mem_device)) {
>>>> -			printk(KERN_ERR PREFIX "Cannot enable memory device\n");
>>>> -			break;
>>>> -		}
>>
>> If acpi_memory_get_device() doesn't fail, it means that the device
>> has been managed by this driver, so I think we can do this cleanup.
>>
>> Thanks
>> Wen Congyang
>>
> 
> Thanks! any comments from Huawei side, Jiang?
Hi Jinsong,

We think it's ok.

acpi_memory_device_notify
	acpi_memory_get_device
		acpi_memory_device_add
			acpi_memory_get_device_resources
			acpi_memory_enable_device
				acpi_memory_get_device_resources（redundant）
	acpi_memory_check_device（redundant）
	acpi_memory_enable_device（redundant）

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