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: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Tested-by: Sakari Ailus <sakari.ailus@linux.intel.com>

1 files changed, 22 insertions, 29 deletions

diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
index 83b03dce576c..5b7c10a2824d 100644
--- a/drivers/acpi/property.c
+++ b/drivers/acpi/property.c
@@ -124,32 +124,12 @@ static bool acpi_nondev_subnode_extract(union acpi_object *desc,
 	return false;
 }
 
-static bool acpi_nondev_subnode_data_ok(acpi_handle handle,
-					const union acpi_object *link,
-					struct list_head *list,
-					struct fwnode_handle *parent)
-{
-	struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER };
-	acpi_status status;
-
-	status = acpi_evaluate_object_typed(handle, NULL, NULL, &buf,
-					    ACPI_TYPE_PACKAGE);
-	if (ACPI_FAILURE(status))
-		return false;
-
-	if (acpi_nondev_subnode_extract(buf.pointer, handle, link, list,
-					parent))
-		return true;
-
-	ACPI_FREE(buf.pointer);
-	return false;
-}
-
 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;
 
@@ -161,7 +141,17 @@ static bool acpi_nondev_subnode_ok(acpi_handle scope,
 	if (ACPI_FAILURE(status))
 		return false;
 
-	return acpi_nondev_subnode_data_ok(handle, link, list, parent);
+	status = acpi_evaluate_object_typed(handle, NULL, NULL, &buf,
+					    ACPI_TYPE_PACKAGE);
+	if (ACPI_FAILURE(status))
+		return false;
+
+	if (acpi_nondev_subnode_extract(buf.pointer, handle, link, list,
+					parent))
+		return true;
+
+	ACPI_FREE(buf.pointer);
+	return false;
 }
 
 static bool acpi_add_nondev_subnodes(acpi_handle scope,
@@ -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;