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

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Date:	Thu, 13 Dec 2012 12:15:18 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Jiang Liu <jiang.liu@...wei.com>
Cc:	"Liu, Jinsong" <jinsong.liu@...el.com>,
	Wen Congyang <wency@...fujitsu.com>,
	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 Thursday, December 13, 2012 10:36:38 AM Jiang Liu wrote:
> 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）

OK, thanks.

I'll queue it up for submission as a fix later in the cycle.

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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