[patch 47/56] ACPICA: Add function to dereference returned reference objects

Greg KH
2009-02-11T00:44:56Z

[-- Attachment #1: acpica-add-function-to-dereference-returned-reference-objects.patch --]
[-- Type: text/plain, Size: 4601 bytes --]

2.6.27-stable review patch. If anyone has any objections, please let us know.
------------------

From: Lin Ming <ming.m.lin@intel.com>

commit bbc241340681557a16982f4d1840f00963bc05b4 upstream.

Examines the return object from a call to acpi_evaluate_object.
Any Index or RefOf references are automatically dereferenced in
an attempt to return something useful (these reference types
cannot be converted into an external ACPI_OBJECT.)
Lin Ming, Bob Moore.

http://bugzilla.kernel.org/show_bug.cgi?id=11105

Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/acpi/namespace/nsxfeval.c | 79 ++++++++++++++++++++++++++++++++++++++
1 file changed, 79 insertions(+)

--- a/drivers/acpi/namespace/nsxfeval.c
+++ b/drivers/acpi/namespace/nsxfeval.c
@@ -45,9 +45,14 @@
#include <acpi/acpi.h>
#include <acpi/acnamesp.h>
#include <acpi/acinterp.h>
+#include <acpi/amlcode.h>

#define _COMPONENT ACPI_NAMESPACE
ACPI_MODULE_NAME("nsxfeval")
+
+/* Local prototypes */
+static void acpi_ns_resolve_references(struct acpi_evaluate_info *info);
+
#ifdef ACPI_FUTURE_USAGE
/*******************************************************************************
*
@@ -69,6 +74,7 @@ ACPI_MODULE_NAME("nsxfeval")
* be valid (non-null)
*
******************************************************************************/
+
acpi_status
acpi_evaluate_object_typed(acpi_handle handle,
acpi_string pathname,
@@ -283,6 +289,10 @@ acpi_evaluate_object(acpi_handle handle,

if (ACPI_SUCCESS(status)) {

+ /* Dereference Index and ref_of references */
+
+ acpi_ns_resolve_references(info);
+
/* Get the size of the returned object */

status =
@@ -352,6 +362,74 @@ ACPI_EXPORT_SYMBOL(acpi_evaluate_object)

/*******************************************************************************
*
+ * FUNCTION: acpi_ns_resolve_references
+ *
+ * PARAMETERS: Info - Evaluation info block
+ *
+ * RETURN: Info->return_object is replaced with the dereferenced object
+ *
+ * DESCRIPTION: Dereference certain reference objects. Called before an
+ * internal return object is converted to an external union acpi_object.
+ *
+ * Performs an automatic dereference of Index and ref_of reference objects.
+ * These reference objects are not supported by the union acpi_object, so this is a
+ * last resort effort to return something useful. Also, provides compatibility
+ * with other ACPI implementations.
+ *
+ * NOTE: does not handle references within returned package objects or nested
+ * references, but this support could be added later if found to be necessary.
+ *
+ ******************************************************************************/
+static void acpi_ns_resolve_references(struct acpi_evaluate_info *info)
+{
+ union acpi_operand_object *obj_desc = NULL;
+ struct acpi_namespace_node *node;
+
+ /* We are interested in reference objects only */
+
+ if (ACPI_GET_OBJECT_TYPE(info->return_object) !=
+ ACPI_TYPE_LOCAL_REFERENCE) {
+ return;
+ }
+
+ /*
+ * Two types of references are supported - those created by Index and
+ * ref_of operators. A name reference (AML_NAMEPATH_OP) can be converted
+ * to an union acpi_object, so it is not dereferenced here. A ddb_handle
+ * (AML_LOAD_OP) cannot be dereferenced, nor can it be converted to
+ * an union acpi_object.
+ */
+ switch (info->return_object->reference.opcode) {
+ case AML_INDEX_OP:
+
+ obj_desc = *(info->return_object->reference.where);
+ break;
+
+ case AML_REF_OF_OP:
+
+ node = info->return_object->reference.object;
+ if (node) {
+ obj_desc = node->object;
+ }
+ break;
+
+ default:
+ return;
+ }
+
+ /* Replace the existing reference object */
+
+ if (obj_desc) {
+ acpi_ut_add_reference(obj_desc);
+ acpi_ut_remove_reference(info->return_object);
+ info->return_object = obj_desc;
+ }
+
+ return;
+}
+
+/*******************************************************************************
+ *
* FUNCTION: acpi_walk_namespace
*
* PARAMETERS: Type - acpi_object_type to search for
@@ -379,6 +457,7 @@ ACPI_EXPORT_SYMBOL(acpi_evaluate_object)
* function, etc.
*
******************************************************************************/
+
acpi_status
acpi_walk_namespace(acpi_object_type type,
acpi_handle start_object,