Subject: Re: [RFC PATCH 1/12] memory-hotplug : rename remove_memory to offline_memory

From: Yasuaki Ishimatsu <[email-masked]>
Date: Thu, 28 Jun 2012 12:01:02 +0900

Hi David and Wen,

Thank you for reviewing my patch.

2012/06/27 17:47, Wen Congyang wrote:
> At 06/27/2012 03:14 PM, Wen Congyang Wrote:
>> At 06/27/2012 01:42 PM, Yasuaki Ishimatsu Wrote:
>>> remove_memory() does not remove memory but just offlines memory. The patch
>>> changes name of it to offline_memory().
>>
>> There are 3 functions in the kernel:
>> 1. add_memory()
>> 2. online_pages()
>> 3. remove_memory()
>>
>> So I think offline_pages() is better than offline_memory().
> 
> There is already a function named offline_pages(). So we
> should call offline_pages() instead of remove_memory() in
> memory_block_action(), and there is no need to rename
> remove_memory().

As Wen says, Linux has 4 functions for memory hotplug already.
In my recognition, these functions are prepared for following purpose.

1. add_memory     : add physical memory
2. online_pages   : online logical memory
3. remove_memory  : offline logical memory
4. offline_pages  : offline logical memory

add_memory() is used for adding physical memory. I think remove_memory()
would rather be used for removing physical memory than be used for removing
logical memory. So I renamed remove_memory() to offline_memory().
How do you think?

Regards,
Yasuaki Ishimatsu

> 
> Thanks
> Wen Congyang
> 
>>
>> Thanks
>> Wen Congyang
>>>
>>> CC: Len Brown <[email-masked]>
>>> CC: Benjamin Herrenschmidt <[email-masked]>
>>> CC: Paul Mackerras <[email-masked]>
>>> CC: Christoph Lameter <[email-masked]>
>>> Cc: Minchan Kim <[email-masked]>
>>> CC: Andrew Morton <[email-masked]>
>>> CC: KOSAKI Motohiro <[email-masked]>
>>> CC: Wen Congyang <[email-masked]>
>>> Signed-off-by: Yasuaki Ishimatsu <[email-masked]>
>>>
>>> ---
>>>   drivers/acpi/acpi_memhotplug.c |    2 +-
>>>   drivers/base/memory.c          |    4 ++--
>>>   include/linux/memory_hotplug.h |    2 +-
>>>   mm/memory_hotplug.c            |    6 +++---
>>>   4 files changed, 7 insertions(+), 7 deletions(-)
>>>
>>> Index: linux-3.5-rc4/drivers/acpi/acpi_memhotplug.c
>>> ===================================================================
>>> --- linux-3.5-rc4.orig/drivers/acpi/acpi_memhotplug.c	2012-06-25 04:53:04.000000000 +0900
>>> +++ linux-3.5-rc4/drivers/acpi/acpi_memhotplug.c	2012-06-26 13:48:38.263940481 +0900
>>> @@ -318,7 +318,7 @@ static int acpi_memory_disable_device(st
>>>   	 */
>>>   	list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
>>>   		if (info->enabled) {
>>> -			result = remove_memory(info->start_addr, info->length);
>>> +			result = offline_memory(info->start_addr, info->length);
>>>   			if (result)
>>>   				return result;
>>>   		}
>>> Index: linux-3.5-rc4/drivers/base/memory.c
>>> ===================================================================
>>> --- linux-3.5-rc4.orig/drivers/base/memory.c	2012-06-25 04:53:04.000000000 +0900
>>> +++ linux-3.5-rc4/drivers/base/memory.c	2012-06-26 13:48:46.072842803 +0900
>>> @@ -266,8 +266,8 @@ memory_block_action(unsigned long phys_i
>>>   			break;
>>>   		case MEM_OFFLINE:
>>>   			start_paddr = page_to_pfn(first_page) << PAGE_SHIFT;
>>> -			ret = remove_memory(start_paddr,
>>> -					    nr_pages << PAGE_SHIFT);
>>> +			ret = offline_memory(start_paddr,
>>> +					     nr_pages << PAGE_SHIFT);
>>>   			break;
>>>   		default:
>>>   			WARN(1, KERN_WARNING "%s(%ld, %ld) unknown action: "
>>> Index: linux-3.5-rc4/mm/memory_hotplug.c
>>> ===================================================================
>>> --- linux-3.5-rc4.orig/mm/memory_hotplug.c	2012-06-25 04:53:04.000000000 +0900
>>> +++ linux-3.5-rc4/mm/memory_hotplug.c	2012-06-26 13:48:46.072842803 +0900
>>> @@ -990,7 +990,7 @@ out:
>>>   	return ret;
>>>   }
>>>
>>> -int remove_memory(u64 start, u64 size)
>>> +int offline_memory(u64 start, u64 size)
>>>   {
>>>   	unsigned long start_pfn, end_pfn;
>>>
>>> @@ -999,9 +999,9 @@ int remove_memory(u64 start, u64 size)
>>>   	return offline_pages(start_pfn, end_pfn, 120 * HZ);
>>>   }
>>>   #else
>>> -int remove_memory(u64 start, u64 size)
>>> +int offline_memory(u64 start, u64 size)
>>>   {
>>>   	return -EINVAL;
>>>   }
>>>   #endif /* CONFIG_MEMORY_HOTREMOVE */
>>> -EXPORT_SYMBOL_GPL(remove_memory);
>>> +EXPORT_SYMBOL_GPL(offline_memory);
>>> Index: linux-3.5-rc4/include/linux/memory_hotplug.h
>>> ===================================================================
>>> --- linux-3.5-rc4.orig/include/linux/memory_hotplug.h	2012-06-25 04:53:04.000000000 +0900
>>> +++ linux-3.5-rc4/include/linux/memory_hotplug.h	2012-06-26 13:48:38.264940468 +0900
>>> @@ -233,7 +233,7 @@ static inline int is_mem_section_removab
>>>   extern int mem_online_node(int nid);
>>>   extern int add_memory(int nid, u64 start, u64 size);
>>>   extern int arch_add_memory(int nid, u64 start, u64 size);
>>> -extern int remove_memory(u64 start, u64 size);
>>> +extern int offline_memory(u64 start, u64 size);
>>>   extern int sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
>>>   								int nr_pages);
>>>   extern void sparse_remove_one_section(struct zone *zone, struct mem_section *ms);
>>>
>>>
>>>
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