linux-kernel - Re: [PATCH] arm64: numa: Don't check node against MAX

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Date:   Tue, 19 Jul 2022 19:09:59 +0100
From:   Will Deacon <will@...nel.org>
To:     Gavin Shan <gshan@...hat.com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        catalin.marinas@....com, shan.gavin@...il.com
Subject: Re: [PATCH] arm64: numa: Don't check node against MAX_NUMNODES

On Mon, Jul 18, 2022 at 02:42:32PM +0800, Gavin Shan wrote:
> When the NUMA nodes are sorted by checking ACPI SRAT (GICC AFFINITY)
> sub-table, it's impossible for acpi_map_pxm_to_node() to return
> any value, which is greater than or equal to MAX_NUMNODES. Lets drop
> the unnecessary check in acpi_numa_gicc_affinity_init().
> 
> No functional change intended.
> 
> Signed-off-by: Gavin Shan <gshan@...hat.com>
> ---
>  arch/arm64/kernel/acpi_numa.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kernel/acpi_numa.c b/arch/arm64/kernel/acpi_numa.c
> index fdfecf0991ce..e51535a5f939 100644
> --- a/arch/arm64/kernel/acpi_numa.c
> +++ b/arch/arm64/kernel/acpi_numa.c
> @@ -109,7 +109,7 @@ void __init acpi_numa_gicc_affinity_init(struct acpi_srat_gicc_affinity *pa)
>  	pxm = pa->proximity_domain;
>  	node = acpi_map_pxm_to_node(pxm);
>  
> -	if (node == NUMA_NO_NODE || node >= MAX_NUMNODES) {
> +	if (node == NUMA_NO_NODE) {
>  		pr_err("SRAT: Too many proximity domains %d\n", pxm);
>  		bad_srat();
>  		return;

This isn't "obviously" correct, but it does look like the way in which
acpi_map_pxm_to_node() allocates nodes in 'nodes_found_map' means that this
check is redundant, so I'll pick it up.

Will