linux-kernel - Re: [PATCH v1 1/4] ACPI: property: Fix buffer properties extraction for subnodes

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Message-ID: <aMfyqjZZwozuRmW_@kekkonen.localdomain>
Date: Mon, 15 Sep 2025 14:04:10 +0300
From: Sakari Ailus <sakari.ailus@...ux.intel.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: Linux ACPI <linux-acpi@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH v1 1/4] ACPI: property: Fix buffer properties extraction
 for subnodes

Hi Rafael,

On Fri, Sep 12, 2025 at 09:39:52PM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> The ACPI handle passed to acpi_extract_properties() as the first
> argument represents the ACPI namespace scope in which to look for
> objects returning buffers associated with buffer properties.
> 
> For _DSD objects located immediately under ACPI devices, this handle is
> the same as the handle of the device object holding the _DSD, but for
> data-only subnodes it is not so.
> 
> First of all, data-only subnodes are represented by objects that
> cannot hold other objects in their scopes (like control methods).
> Therefore a data-only subnode handle cannot be used for completing
> relative pathname segments, so the current code in
> in acpi_nondev_subnode_extract() passing a data-only subnode handle
> to acpi_extract_properties() is invalid.
> 
> Moreover, a data-only subnode of device A may be represented by an
> object located in the scope of device B (which kind of makes sense,
> for instance, if A is a B's child).  In that case, the scope in
> question would be the one of device B.  In other words, the scope
> mentioned above is the same as the scope used for subnode object
> lookup in acpi_nondev_subnode_extract().
> 
> Accordingly, rearrange that function to use the same scope for the
> extraction of properties and subnode object lookup.
> 
> Fixes: 103e10c69c61 ("ACPI: property: Add support for parsing buffer property UUID")

I believe the commit introducing this is
99db5ff7fe0b4e1657423d7bbe2aa8f655dd02d1 .

> Cc: 6.0+ <stable@...r.kernel.org> # 6.0+
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>  drivers/acpi/property.c |   30 +++++++++++-------------------
>  1 file changed, 11 insertions(+), 19 deletions(-)
> 
> --- a/drivers/acpi/property.c
> +++ b/drivers/acpi/property.c
> @@ -83,6 +83,7 @@ static bool acpi_nondev_subnode_extract(
>  					struct fwnode_handle *parent)
>  {
>  	struct acpi_data_node *dn;
> +	acpi_handle scope = NULL;
>  	bool result;
>  
>  	if (acpi_graph_ignore_port(handle))
> @@ -98,27 +99,18 @@ static bool acpi_nondev_subnode_extract(
>  	INIT_LIST_HEAD(&dn->data.properties);
>  	INIT_LIST_HEAD(&dn->data.subnodes);
>  
> -	result = acpi_extract_properties(handle, desc, &dn->data);
> +	/*
> +	 * The scope for the completion of relative pathname segments and
> +	 * subnode object lookup is the one of the namespace node (device)
> +	 * containing the object that has returned the package.  That is, it's
> +	 * the scope of that object's parent device.
> +	 */
> +	if (handle)
> +		acpi_get_parent(handle, &scope);
>  
> -	if (handle) {
> -		acpi_handle scope;
> -		acpi_status status;
> -
> -		/*
> -		 * The scope for the subnode object lookup is the one of the
> -		 * namespace node (device) containing the object that has
> -		 * returned the package.  That is, it's the scope of that
> -		 * object's parent.
> -		 */
> -		status = acpi_get_parent(handle, &scope);
> -		if (ACPI_SUCCESS(status)
> -		    && acpi_enumerate_nondev_subnodes(scope, desc, &dn->data,
> -						      &dn->fwnode))
> -			result = true;
> -	} else if (acpi_enumerate_nondev_subnodes(NULL, desc, &dn->data,
> -						  &dn->fwnode)) {
> +	result = acpi_extract_properties(scope, desc, &dn->data);
> +	if (acpi_enumerate_nondev_subnodes(scope, desc, &dn->data, &dn->fwnode))
>  		result = true;
> -	}
>  
>  	if (result) {
>  		dn->handle = handle;
> 
> 

-- 
Kind regards,

Sakari Ailus