linux-kernel - Re: [PATCH v3 3/3] acpi,memory-hotplug : add memory offline code to acpi_memory_device

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Date:	Fri, 26 Oct 2012 11:14:31 -0600
From:	Toshi Kani <toshi.kani@...com>
To:	wency@...fujitsu.com
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	linux-acpi@...r.kernel.org, liuj97@...il.com, len.brown@...el.com,
	akpm@...ux-foundation.org, kosaki.motohiro@...fujitsu.com,
	isimatu.yasuaki@...fujitsu.com, rjw@...k.pl, laijs@...fujitsu.com,
	David Rientjes <rientjes@...gle.com>,
	Christoph Lameter <cl@...ux.com>,
	Minchan Kim <minchan.kim@...il.com>
Subject: Re: [PATCH v3 3/3] acpi,memory-hotplug : add memory offline code to
 acpi_memory_device_remove()

On Fri, 2012-10-26 at 18:31 +0800, wency@...fujitsu.com wrote:
> From: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
> 
> The memory device can be removed by 2 ways:
> 1. send eject request by SCI
> 2. echo 1 >/sys/bus/pci/devices/PNP0C80:XX/eject
> 
> In the 1st case, acpi_memory_disable_device() will be called.
> In the 2nd case, acpi_memory_device_remove() will be called.

Hi Yasuaki, Wen,

Why do you need to have separate code design & implementation for the
two cases?  In other words, can the 1st case simply use the same code
path of the 2nd case, just like I did for the CPU hot-remove patch
below?  It will simplify the code and make the memory notify handler
more consistent with other handlers.
https://lkml.org/lkml/2012/10/19/456

Thanks,
-Toshi


> acpi_memory_device_remove() will also be called when we unbind the
> memory device from the driver acpi_memhotplug or a driver initialization
> fails.
> 
> acpi_memory_disable_device() has already implemented a code which
> offlines memory and releases acpi_memory_info struct. But
> acpi_memory_device_remove() has not implemented it yet.
> 
> So the patch move offlining memory and releasing acpi_memory_info struct
> codes to a new function acpi_memory_remove_memory(). And it is used by both
> acpi_memory_device_remove() and acpi_memory_disable_device().
> 
> CC: David Rientjes <rientjes@...gle.com>
> CC: Jiang Liu <liuj97@...il.com>
> CC: Len Brown <len.brown@...el.com>
> CC: Christoph Lameter <cl@...ux.com>
> Cc: Minchan Kim <minchan.kim@...il.com>
> CC: Andrew Morton <akpm@...ux-foundation.org>
> CC: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
> Signed-off-by: Wen Congyang <wency@...fujitsu.com>
> ---
>  drivers/acpi/acpi_memhotplug.c | 31 ++++++++++++++++++++++++-------
>  1 file changed, 24 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
> index 666dac6..92c973a 100644
> --- a/drivers/acpi/acpi_memhotplug.c
> +++ b/drivers/acpi/acpi_memhotplug.c
> @@ -316,16 +316,11 @@ static int acpi_memory_powerdown_device(struct acpi_memory_device *mem_device)
>  	return 0;
>  }
>  
> -static int acpi_memory_disable_device(struct acpi_memory_device *mem_device)
> +static int acpi_memory_remove_memory(struct acpi_memory_device *mem_device)
>  {
>  	int result;
>  	struct acpi_memory_info *info, *n;
>  
> -
> -	/*
> -	 * Ask the VM to offline this memory range.
> -	 * Note: Assume that this function returns zero on success
> -	 */
>  	mutex_lock(&mem_device->list_lock);
>  	list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
>  		if (info->enabled) {
> @@ -333,10 +328,27 @@ static int acpi_memory_disable_device(struct acpi_memory_device *mem_device)
>  			if (result)
>  				return result;
>  		}
> +
> +		list_del(&info->list);
>  		kfree(info);
>  	}
>  	mutex_unlock(&mem_device->list_lock);
>  
> +	return 0;
> +}
> +
> +static int acpi_memory_disable_device(struct acpi_memory_device *mem_device)
> +{
> +	int result;
> +
> +	/*
> +	 * Ask the VM to offline this memory range.
> +	 * Note: Assume that this function returns zero on success
> +	 */
> +	result = acpi_memory_remove_memory(mem_device);
> +	if (result)
> +		return result;
> +
>  	/* Power-off and eject the device */
>  	result = acpi_memory_powerdown_device(mem_device);
>  	if (result) {
> @@ -487,12 +499,17 @@ static int acpi_memory_device_add(struct acpi_device *device)
>  static int acpi_memory_device_remove(struct acpi_device *device, int type)
>  {
>  	struct acpi_memory_device *mem_device = NULL;
> -
> +	int result;
>  
>  	if (!device || !acpi_driver_data(device))
>  		return -EINVAL;
>  
>  	mem_device = acpi_driver_data(device);
> +
> +	result = acpi_memory_remove_memory(mem_device);
> +	if (result)
> +		return result;
> +
>  	kfree(mem_device);
>  
>  	return 0;


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