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

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Message-ID: <CAJZ5v0g98Tt43y-jCS4Vn9hhv1HtcjcyeOkSv21zswhpxc0TRg@mail.gmail.com>
Date: Mon, 15 Sep 2025 14:09:03 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, 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 Sakari,

On Mon, Sep 15, 2025 at 1:04 PM Sakari Ailus
<sakari.ailus@...ux.intel.com> wrote:
>
> 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 .

No, it isn't.  Prior to commit 103e10c69c61, scope was not passed to
acpi_extract_properties().

> > 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;
> >
> >
>
> --