ACPICA: Performance enhancement for namespace search and access

This change enhances the performance of namespace searches and
walks by adding a backpointer to the parent in each namespace
node. On large namespaces, this change can improve overall ACPI
performance by up to 9X.  Adding a pointer to each namespace node
increases the overall size of the internal namespace by about 5%,
since each namespace entry usually consists of both a namespace
node and an ACPI operand object.

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/acpica/nsnames.c b/drivers/acpi/acpica/nsnames.c
index 7dea003..d3104af 100644
--- a/drivers/acpi/acpica/nsnames.c
+++ b/drivers/acpi/acpica/nsnames.c
@@ -93,7 +93,7 @@
 		/* Put the name into the buffer */
 
 		ACPI_MOVE_32_TO_32((name_buffer + index), &parent_node->name);
-		parent_node = acpi_ns_get_parent_node(parent_node);
+		parent_node = parent_node->parent;
 
 		/* Prefix name with the path separator */
 
@@ -198,7 +198,7 @@
 			return 0;
 		}
 		size += ACPI_PATH_SEGMENT_LENGTH;
-		next_node = acpi_ns_get_parent_node(next_node);
+		next_node = next_node->parent;
 	}
 
 	if (!size) {