Re: [PATCH v1 06/17] platform/x86: serdev_helpers: Switch to use acpi_bus_get_primary_device()

[Ilpo Järvinen]

On Mon, 21 Sep 2026, Rafael J. Wysocki wrote:

> From: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx>
> 
> Replace acpi_get_first_physical_node() that is slated for removal
> with acpi_bus_get_primary_device() that takes a reference to the
> device it is about to return.
> 
> This addresses a potential use-after-free that may occur if the
> device returned by acpi_get_first_physical_node() is removed right
> after dropping its ACPI companion's physical_node_lock in that
> function.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
>  drivers/platform/x86/serdev_helpers.h | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/platform/x86/serdev_helpers.h b/drivers/platform/x86/serdev_helpers.h
> index 57eac75805e2..20267e1941f1 100644
> --- a/drivers/platform/x86/serdev_helpers.h
> +++ b/drivers/platform/x86/serdev_helpers.h
> @@ -74,8 +74,7 @@ get_serdev_controller(const char *serial_ctrl_hid,
>  		return ERR_PTR(-ENODEV);
>  	}
>  
> -	/* get_first_physical_node() returns a weak ref */
> -	parent = get_device(acpi_get_first_physical_node(adev));
> +	parent = acpi_bus_get_primary_device(adev);
>  	acpi_dev_put(adev);
>  	if (!parent) {
>  		pr_err("error could not get %s/%s serial-ctrl physical node\n",
> 

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>

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