linux-kernel - Re: [PATCH 4/7] Allow sysfs memory directories to be split

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Message-Id: <20100713152854.ec1f4d6a.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Tue, 13 Jul 2010 15:28:54 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Nathan Fontenot <nfont@...tin.ibm.com>
Cc:	linux-kernel@...r.kernel.org, linuxppc-dev@...abs.org
Subject: Re: [PATCH 4/7] Allow sysfs memory directories to be split

On Mon, 12 Jul 2010 10:45:25 -0500
Nathan Fontenot <nfont@...tin.ibm.com> wrote:

> This patch introduces the new 'split' file in each memory sysfs
> directory and the associated routines needed to handle splitting
> a directory.
> 
> Signed-off-by; Nathan Fontenot <nfont@...tin.ibm.com>
> ---

pleae check diff option...


>  drivers/base/memory.c |   99 +++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 98 insertions(+), 1 deletion(-)
> 
> Index: linux-2.6/drivers/base/memory.c
> ===================================================================
> --- linux-2.6.orig/drivers/base/memory.c	2010-07-09 14:23:20.000000000 -0500
> +++ linux-2.6/drivers/base/memory.c	2010-07-09 14:38:09.000000000 -0500
> @@ -32,6 +32,9 @@
>  
>  static int sections_per_block;
>  
> +static int register_memory(struct memory_block *, struct mem_section *,
> +			   int, enum mem_add_context);
> +
>  static inline int base_memory_block_id(int section_nr)
>  {
>  	return (section_nr / sections_per_block) * sections_per_block;
> @@ -309,11 +312,100 @@
>  	return sprintf(buf, "%d\n", mem->phys_device);
>  }
>  
> +static void update_memory_block_phys_indexes(struct memory_block *mem)
> +{
> +	struct list_head *pos;
> +	struct memory_block_section *mbs;
> +	unsigned long min_index = 0xffffffff;
> +	unsigned long max_index = 0;
> +
> +	list_for_each(pos, &mem->sections) {
> +		mbs = list_entry(pos, struct memory_block_section, next);
> +
> +		if (mbs->phys_index < min_index)
> +			min_index = mbs->phys_index;
> +
> +		if (mbs->phys_index > max_index)
> +			max_index = mbs->phys_index;
> +	}
> +
> +	mem->start_phys_index = min_index;
> +	mem->end_phys_index = max_index;
> +}
> +
> +static ssize_t
> +store_mem_split_block(struct sys_device *dev, struct sysdev_attribute *attr,
> +		      const char *buf, size_t count)
> +{
> +	struct memory_block *mem, *new_mem_blk;
> +	struct memory_block_section *mbs;
> +	struct list_head *pos, *tmp;
> +	struct mem_section *section;
> +	int min_scn_nr = 0;
> +	int max_scn_nr = 0;
> +	int total_scns = 0;
> +	int new_blk_min, new_blk_total;
> +	int ret = -EINVAL;
> +
> +	mem = container_of(dev, struct memory_block, sysdev);
> +
> +	if (list_is_singular(&mem->sections))
> +		return -EINVAL;

What this means ?


> +
> +	mutex_lock(&mem->state_mutex);
> +
> +	list_for_each(pos, &mem->sections) {
> +		mbs = list_entry(pos, struct memory_block_section, next);
> +
> +		total_scns++;
> +
> +		if (min_scn_nr > mbs->phys_index)
> +			min_scn_nr = mbs->phys_index;
> +
> +		if (max_scn_nr < mbs->phys_index)
> +			max_scn_nr = mbs->phys_index;
> +	}
> +
> +	new_mem_blk = kzalloc(sizeof(*new_mem_blk), GFP_KERNEL);
> +	if (!new_mem_blk)
> +		return -ENOMEM;
> +
> +	mutex_init(&new_mem_blk->state_mutex);
> +	INIT_LIST_HEAD(&new_mem_blk->sections);
> +	new_mem_blk->state = mem->state;
> +
> +	mutex_lock(&new_mem_blk->state_mutex);
> +
> +	new_blk_total = total_scns / 2;
> +	new_blk_min = max_scn_nr - new_blk_total + 1;
> +
> +	section = __nr_to_section(new_blk_min);
> +	ret = register_memory(new_mem_blk, section, 0, HOTPLUG);
> +
'nid' is always 0 ?

And for what purpose this interface is ? Does this split memory block into 2 pieces
of the same size ?? sounds __very__ strange interface to me.

If this is necessary, I hope move the whole things to configfs rather than
something tricky.

Bye.
-Kame

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