linux-kernel - Re: [PATCH 7/7] drivers: base: refactor add_memory_section() to add_memory

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Date:	Thu, 22 Aug 2013 17:20:03 +0900
From:	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
To:	Seth Jennings <sjenning@...ux.vnet.ibm.com>
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Dave Hansen <dave@...1.net>,
	Nathan Fontenot <nfont@...ux.vnet.ibm.com>,
	Cody P Schafer <cody@...ux.vnet.ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Yinghai Lu <yinghai@...nel.org>,
	Wanpeng Li <liwanp@...ux.vnet.ibm.com>,
	<linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
	<linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH 7/7] drivers: base: refactor add_memory_section() to add_memory_block()

(2013/08/21 2:13), Seth Jennings wrote:
> Right now memory_dev_init() maintains the memory block pointer
> between iterations of add_memory_section().  This is nasty.
> 
> This patch refactors add_memory_section() to become add_memory_block().
> The refactoring pulls the section scanning out of memory_dev_init()
> and simplifies the signature.
> 
> Signed-off-by: Seth Jennings <sjenning@...ux.vnet.ibm.com>
> ---
>   drivers/base/memory.c | 48 +++++++++++++++++++++---------------------------
>   1 file changed, 21 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> index 7d9d3bc..021283a 100644
> --- a/drivers/base/memory.c
> +++ b/drivers/base/memory.c
> @@ -602,32 +602,31 @@ static int init_memory_block(struct memory_block **memory,
>   	return ret;
>   }
>   
> -static int add_memory_section(struct mem_section *section,
> -			struct memory_block **mem_p)
> +static int add_memory_block(int base_section_nr)
>   {
> -	struct memory_block *mem = NULL;
> -	int scn_nr = __section_nr(section);
> -	int ret = 0;
> -
> -	if (mem_p && *mem_p) {
> -		if (scn_nr >= (*mem_p)->start_section_nr &&
> -		    scn_nr <= (*mem_p)->end_section_nr) {
> -			mem = *mem_p;
> -		}
> -	}
> +	struct memory_block *mem;
> +	int i, ret, section_count = 0, section_nr;
>   
> -	if (mem)
> -		mem->section_count++;
> -	else {
> -		ret = init_memory_block(&mem, section, MEM_ONLINE);
> -		/* store memory_block pointer for next loop */
> -		if (!ret && mem_p)
> -			*mem_p = mem;
> +	for (i = base_section_nr;
> +	     (i < base_section_nr + sections_per_block) && i < NR_MEM_SECTIONS;
> +	     i++) {
> +		if (!present_section_nr(i))
> +			continue;
> +		if (section_count == 0)
> +			section_nr = i;
> +		section_count++;
>   	}
>   
> -	return ret;
> +	if (section_count == 0)
> +		return 0;
> +	ret = init_memory_block(&mem, __nr_to_section(section_nr), MEM_ONLINE);
> +	if (ret)
> +		return ret;
> +	mem->section_count = section_count;
> +	return 0;
>   }
>   
> +
>   /*
>    * need an interface for the VM to add new memory regions,
>    * but without onlining it.
> @@ -733,7 +732,6 @@ int __init memory_dev_init(void)
>   	int ret;
>   	int err;
>   	unsigned long block_sz;
> -	struct memory_block *mem = NULL;
>   
>   	ret = subsys_system_register(&memory_subsys, memory_root_attr_groups);
>   	if (ret)
> @@ -747,12 +745,8 @@ int __init memory_dev_init(void)
>   	 * during boot and have been initialized
>   	 */
>   	mutex_lock(&mem_sysfs_mutex);
> -	for (i = 0; i < NR_MEM_SECTIONS; i++) {
> -		if (!present_section_nr(i))
> -			continue;
> -		/* don't need to reuse memory_block if only one per block */
> -		err = add_memory_section(__nr_to_section(i),
> -				 (sections_per_block == 1) ? NULL : &mem);
> +	for (i = 0; i < NR_MEM_SECTIONS; i += sections_per_block) {

Why do you remove present_setcion_nr() check?

> +		err = add_memory_block(i);
>   		if (!ret)

Thanks,
Yasuaki Ishimatasu

>   			ret = err;
>   	}
> 


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