linux-kernel - Re: [PATCH v3 08/12] arm64, numa: rework numa_add

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Date:	Wed, 9 Mar 2016 13:27:44 +0100
From:	Robert Richter <robert.richter@...iumnetworks.com>
To:	Hanjun Guo <guohanjun@...wei.com>
CC:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Will Deacon <will.deacon@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	<linux-acpi@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>,
	Ganapatrao Kulkarni <gkulkarni@...iumnetworks.com>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
	Shannon Zhao <shannon.zhao@...aro.org>,
	Steve Capper <steve.capper@...aro.org>,
	Mark Rutland <mark.rutland@....com>,
	Hanjun Guo <hanjun.guo@...aro.org>
Subject: Re: [PATCH v3 08/12] arm64, numa: rework numa_add_memblk()

On 23.01.16 17:39:23, Hanjun Guo wrote:
> From: Hanjun Guo <hanjun.guo@...aro.org>
> 
> Rework numa_add_memblk() to update the parameter "u64 size"
> to "u64 end", this will make it consistent with x86 and
> can simplify the code later.
> 
> Updates for arch/arm64/mm/numa.c should squash to core NUMA
> patches from Ganapat.
> 
> Signed-off-by: Hanjun Guo <hanjun.guo@...aro.org>
> ---
>  arch/arm64/kernel/acpi_numa.c |  2 +-
>  arch/arm64/kernel/of_numa.c   |  2 +-
>  arch/arm64/mm/numa.c          | 12 ++++++------
>  3 files changed, 8 insertions(+), 8 deletions(-)

> diff --git a/arch/arm64/kernel/of_numa.c b/arch/arm64/kernel/of_numa.c
> index 2f9e34b..aa6f3a3 100644
> --- a/arch/arm64/kernel/of_numa.c
> +++ b/arch/arm64/kernel/of_numa.c
> @@ -168,7 +168,7 @@ static int __init early_init_parse_memory_node(unsigned long node)
>  		pr_debug("NUMA-DT:  base = %llx , node = %u\n",
>  				base, nid);
>  
> -		if (numa_add_memblk(nid, base, size) < 0)
> +		if (numa_add_memblk(nid, base, base + size) < 0)
>  			return -EINVAL;
>  	}
>  
> diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
> index e974995..2b04b8a 100644
> --- a/arch/arm64/mm/numa.c
> +++ b/arch/arm64/mm/numa.c
> @@ -137,25 +137,25 @@ void numa_store_cpu_info(unsigned int cpu)
>   * numa_add_memblk - Set node id to memblk
>   * @nid: NUMA node ID of the new memblk
>   * @start: Start address of the new memblk
> - * @size:  Size of the new memblk
> + * @end:  End address of the new memblk

Apart from my earlier comment, this is not exactly correct and may
cause confussion. The implementation here defines:

 size == end - start

which is different to struct resource, where:

 resource_size(res) == res->end - res->start + 1

Thus, @end here is the first address outside of memblk.

This is one more argument for keeping @size here.

-Robert

>   *
>   * RETURNS:
>   * 0 on success, -errno on failure.
>   */
> -int __init numa_add_memblk(int nid, u64 start, u64 size)
> +int __init numa_add_memblk(int nid, u64 start, u64 end)
>  {
>  	int ret;
>  
> -	ret = memblock_set_node(start, size, &memblock.memory, nid);
> +	ret = memblock_set_node(start, (end - start), &memblock.memory, nid);
>  	if (ret < 0) {
>  		pr_err("NUMA: memblock [0x%llx - 0x%llx] failed to add on node %d\n",
> -			start, (start + size - 1), nid);
> +			start, (end - 1), nid);
>  		return ret;
>  	}
>  
>  	node_set(nid, numa_nodes_parsed);
>  	pr_info("NUMA: Adding memblock [0x%llx - 0x%llx] on node %d\n",
> -			start, (start + size - 1), nid);
> +			start, (end - 1), nid);
>  	return ret;
>  }