ACPICA: Fix for Alias operator to see target child objects

Fixed a problem with the Alias operator when the target of the
alias is a named ASL operator that opens a new scope -- Scope,
Device, PowerResource, Processor, and ThermalZone. In these cases,
any children of the original operator could not be accessed via
the alias, potentially causing unexpected AE_NOT_FOUND exceptions.

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 60 insertions, 36 deletions

diff --git a/drivers/acpi/namespace/nsaccess.c b/drivers/acpi/namespace/nsaccess.c
index 32a01673cae8..54852fbfc878 100644
--- a/drivers/acpi/namespace/nsaccess.c
+++ b/drivers/acpi/namespace/nsaccess.c
@@ -581,44 +581,68 @@ acpi_ns_lookup(union acpi_generic_state *scope_info,
                         return_ACPI_STATUS(status);
                 }
 
-                /*
-                 * Sanity typecheck of the target object:
-                 *
-                 * If 1) This is the last segment (num_segments == 0)
-                 *    2) And we are looking for a specific type
-                 *       (Not checking for TYPE_ANY)
-                 *    3) Which is not an alias
-                 *    4) Which is not a local type (TYPE_SCOPE)
-                 *    5) And the type of target object is known (not TYPE_ANY)
-                 *    6) And target object does not match what we are looking for
-                 *
-                 * Then we have a type mismatch.  Just warn and ignore it.
-                 */
-                if ((num_segments == 0) &&
-                    (type_to_check_for != ACPI_TYPE_ANY) &&
-                    (type_to_check_for != ACPI_TYPE_LOCAL_ALIAS) &&
-                    (type_to_check_for != ACPI_TYPE_LOCAL_METHOD_ALIAS) &&
-                    (type_to_check_for != ACPI_TYPE_LOCAL_SCOPE) &&
-                    (this_node->type != ACPI_TYPE_ANY) &&
-                    (this_node->type != type_to_check_for)) {
-
-                        /* Complain about a type mismatch */
-
-                        ACPI_WARNING((AE_INFO,
-                                      "NsLookup: Type mismatch on %4.4s (%s), searching for (%s)",
-                                      ACPI_CAST_PTR(char, &simple_name),
-                                      acpi_ut_get_type_name(this_node->type),
-                                      acpi_ut_get_type_name
-                                      (type_to_check_for)));
+                /* More segments to follow? */
+
+                if (num_segments > 0) {
+                        /*
+                         * If we have an alias to an object that opens a scope (such as a
+                         * device or processor), we need to dereference the alias here so that
+                         * we can access any children of the original node (via the remaining
+                         * segments).
+                         */
+                        if (this_node->type == ACPI_TYPE_LOCAL_ALIAS) {
+                                if (acpi_ns_opens_scope
+                                    (((struct acpi_namespace_node *)this_node->
+                                      object)->type)) {
+                                        this_node =
+                                            (struct acpi_namespace_node *)
+                                            this_node->object;
+                                }
+                        }
                 }
 
-                /*
-                 * If this is the last name segment and we are not looking for a
-                 * specific type, but the type of found object is known, use that type
-                 * to see if it opens a scope.
-                 */
-                if ((num_segments == 0) && (type == ACPI_TYPE_ANY)) {
-                        type = this_node->type;
+                /* Special handling for the last segment (num_segments == 0) */
+
+                else {
+                        /*
+                         * Sanity typecheck of the target object:
+                         *
+                         * If 1) This is the last segment (num_segments == 0)
+                         *    2) And we are looking for a specific type
+                         *       (Not checking for TYPE_ANY)
+                         *    3) Which is not an alias
+                         *    4) Which is not a local type (TYPE_SCOPE)
+                         *    5) And the type of target object is known (not TYPE_ANY)
+                         *    6) And target object does not match what we are looking for
+                         *
+                         * Then we have a type mismatch. Just warn and ignore it.
+                         */
+                        if ((type_to_check_for != ACPI_TYPE_ANY) &&
+                            (type_to_check_for != ACPI_TYPE_LOCAL_ALIAS) &&
+                            (type_to_check_for != ACPI_TYPE_LOCAL_METHOD_ALIAS)
+                            && (type_to_check_for != ACPI_TYPE_LOCAL_SCOPE)
+                            && (this_node->type != ACPI_TYPE_ANY)
+                            && (this_node->type != type_to_check_for)) {
+
+                                /* Complain about a type mismatch */
+
+                                ACPI_WARNING((AE_INFO,
+                                              "NsLookup: Type mismatch on %4.4s (%s), searching for (%s)",
+                                              ACPI_CAST_PTR(char, &simple_name),
+                                              acpi_ut_get_type_name(this_node->
+                                                                    type),
+                                              acpi_ut_get_type_name
+                                              (type_to_check_for)));
+                        }
+
+                        /*
+                         * If this is the last name segment and we are not looking for a
+                         * specific type, but the type of found object is known, use that type
+                         * to (later) see if it opens a scope.
+                         */
+                        if (type == ACPI_TYPE_ANY) {
+                                type = this_node->type;
+                        }
                 }
 
                 /* Point to next name segment and make this node current */