[PATCH v2 5/6] ACPI: Remove side effect of partly creating a node in acpi_get_node

[Song Bao Hua (Barry Song)]

> -----Original Message-----
> From: Jonathan Cameron
> Sent: Saturday, July 18, 2020 6:00 AM
> To: linux-mm at kvack.org; linux-acpi at vger.kernel.org;
> linux-arm-kernel at lists.infradead.org; x86 at kernel.org
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>; Bjorn Helgaas
> <bhelgaas at google.com>; linux-pci at vger.kernel.org; martin at geanix.com; Ingo
> Molnar <mingo at redhat.com>; linux-ia64 at vger.kernel.org; Tony Luck
> <tony.luck at intel.com>; Fenghua Yu <fenghua.yu at intel.com>; Thomas
> Gleixner <tglx at linutronix.de>; Linuxarm <linuxarm at huawei.com>; Dan
> Williams <dan.j.williams at intel.com>; Song Bao Hua (Barry Song)
> <song.bao.hua at hisilicon.com>; Jonathan Cameron
> <jonathan.cameron at huawei.com>
> Subject: [PATCH v2 5/6] ACPI: Remove side effect of partly creating a node in
> acpi_get_node
> 
> acpi_get_node calls acpi_get_pxm to evaluate the _PXM AML method for
> entries found in DSDT/SSDT. ACPI 6.3 sec 6.2.14 states
> "_PXM evaluates to an integer that identifies a device as belonging to
>  a Proximity Domain defined in the System Resource Affinity Table (SRAT)."
> 
> Hence a _PXM method should not result in creation of a new NUMA node.
> Before this patch, _PXM could result in partial instantiation of
> NUMA node, missing elements such as zone lists.  A call to devm_kzalloc
> for example results in a null pointer dereference.
> 
> This patch therefore replaces the acpi_map_pxm_to_node with a call
> to pxm_to_node.
> 
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron at huawei.com>

Reviewed-by: Barry Song <song.bao.hua at hisilicon.com>

> ---
>  drivers/acpi/numa/srat.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/numa/srat.c b/drivers/acpi/numa/srat.c
> index 8ef44ee0d76b..697a5c9e2eb5 100644
> --- a/drivers/acpi/numa/srat.c
> +++ b/drivers/acpi/numa/srat.c
> @@ -444,6 +444,6 @@ int acpi_get_node(acpi_handle handle)
> 
>  	pxm = acpi_get_pxm(handle);
> 
> -	return acpi_map_pxm_to_node(pxm);
> +	return pxm_to_node(pxm);
>  }
>  EXPORT_SYMBOL(acpi_get_node);
> --
> 2.19.1