Commit d06118fe authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

ACPI: property: Disregard references in data-only subnode lists 

Data-only subnode links following the ACPI data subnode GUID in a _DSD
package are expected to point to named objects returning _DSD-equivalent
packages.  If a reference to such an object is used in the target field
of any of those links, that object will be evaluated in place (as a
named object) and its return data will be embedded in the outer _DSD
package.

For this reason, it is not expected to see a subnode link with the
target field containing a local reference (that would mean pointing
to a device or another object that cannot be evaluated in place and
therefore cannot return a _DSD-equivalent package).

Accordingly, simplify the code parsing data-only subnode links to
simply print a message when it encounters a local reference in the
target field of one of those links.

Moreover, since acpi_nondev_subnode_data_ok() would only have one
caller after the change above, fold it into that caller.

Link: https://lore.kernel.org/linux-acpi/CAJZ5v0jVeSrDO6hrZhKgRZrH=FpGD4vNUjFD8hV9WwN9TLHjzQ@mail.gmail.com/


Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: default avatarSakari Ailus <sakari.ailus@linux.intel.com>
Tested-by: default avatarSakari Ailus <sakari.ailus@linux.intel.com>
parent d0759b10

drivers/acpi/property.c

+22 −29
Original line number Diff line number Diff line
@@ -124,14 +124,23 @@ static bool acpi_nondev_subnode_extract(union acpi_object *desc, 
	return false;

}



static bool acpi_nondev_subnode_data_ok(acpi_handle handle,

static bool acpi_nondev_subnode_ok(acpi_handle scope,

				   const union acpi_object *link,

				   struct list_head *list,

				   struct fwnode_handle *parent)

{

	struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER };

	acpi_handle handle;

	acpi_status status;



	if (!scope)

		return false;



	status = acpi_get_handle(scope, link->package.elements[1].string.pointer,

				 &handle);

	if (ACPI_FAILURE(status))

		return false;



	status = acpi_evaluate_object_typed(handle, NULL, NULL, &buf,

					    ACPI_TYPE_PACKAGE);

	if (ACPI_FAILURE(status))
@@ -145,25 +154,6 @@ static bool acpi_nondev_subnode_data_ok(acpi_handle handle, 
	return false;

}



static bool acpi_nondev_subnode_ok(acpi_handle scope,

				   const union acpi_object *link,

				   struct list_head *list,

				   struct fwnode_handle *parent)

{

	acpi_handle handle;

	acpi_status status;



	if (!scope)

		return false;



	status = acpi_get_handle(scope, link->package.elements[1].string.pointer,

				 &handle);

	if (ACPI_FAILURE(status))

		return false;



	return acpi_nondev_subnode_data_ok(handle, link, list, parent);

}



static bool acpi_add_nondev_subnodes(acpi_handle scope,

				     union acpi_object *links,

				     struct list_head *list,
@@ -174,7 +164,6 @@ static bool acpi_add_nondev_subnodes(acpi_handle scope, 


	for (i = 0; i < links->package.count; i++) {

		union acpi_object *link, *desc;

		acpi_handle handle;

		bool result;



		link = &links->package.elements[i];
@@ -186,22 +175,26 @@ static bool acpi_add_nondev_subnodes(acpi_handle scope, 
		if (link->package.elements[0].type != ACPI_TYPE_STRING)

			continue;



		/* The second one may be a string, a reference or a package. */

		/* The second one may be a string or a package. */

		switch (link->package.elements[1].type) {

		case ACPI_TYPE_STRING:

			result = acpi_nondev_subnode_ok(scope, link, list,

							 parent);

			break;

		case ACPI_TYPE_LOCAL_REFERENCE:

			handle = link->package.elements[1].reference.handle;

			result = acpi_nondev_subnode_data_ok(handle, link, list,

							     parent);

			break;

		case ACPI_TYPE_PACKAGE:

			desc = &link->package.elements[1];

			result = acpi_nondev_subnode_extract(desc, NULL, link,

							     list, parent);

			break;

		case ACPI_TYPE_LOCAL_REFERENCE:

			/*

			 * It is not expected to see any local references in

			 * the links package because referencing a named object

			 * should cause it to be evaluated in place.

			 */

			acpi_handle_info(scope, "subnode %s: Unexpected reference\n",

					 link->package.elements[0].string.pointer);

			fallthrough;

		default:

			result = false;

			break;