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>

drivers/acpi/acpica/nssearch.c

@@ -152,17 +152,6 @@ acpi_ns_search_one_scope(u32 target_name,
 			return_ACPI_STATUS(AE_OK);
 		}
 
-		/*
-		 * The last entry in the list points back to the parent,
-		 * so a flag is used to indicate the end-of-list
-		 */
-		if (node->flags & ANOBJ_END_OF_PEER_LIST) {
-
-			/* Searched entire list, we are done */
-
-			break;
-		}
-
 		/* Didn't match name, move on to the next peer object */
 
 		node = node->peer;
@@ -217,7 +206,7 @@ acpi_ns_search_parent_tree(u32 target_name,
 
 	ACPI_FUNCTION_TRACE(ns_search_parent_tree);
 
-	parent_node = acpi_ns_get_parent_node(node);
+	parent_node = node->parent;
 
 	/*
 	 * If there is no parent (i.e., we are at the root) or type is "local",
@@ -261,7 +250,7 @@ acpi_ns_search_parent_tree(u32 target_name,
 
 		/* Not found here, go up another level (until we reach the root) */
 
-		parent_node = acpi_ns_get_parent_node(parent_node);
+		parent_node = parent_node->parent;
 	}
 
 	/* Not found in parent tree */