ACPICA: Fix race condition with AcpiWalkNamespace.

Fixed a problem with a possible race condition between threads executing
AcpiWalkNamespace and the AML interpreter. This condition was removed by
modifying AcpiWalkNamespace to (by default) ignore all temporary
namespace entries created during any concurrent control method execution

Signed-off-by: Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

4 files changed, 22 insertions, 8 deletions

diff --git a/drivers/acpi/dispatcher/dswload.c b/drivers/acpi/dispatcher/dswload.c
index 565d4557d0e0..4ed08680ae7c 100644
--- a/drivers/acpi/dispatcher/dswload.c
+++ b/drivers/acpi/dispatcher/dswload.c
@@ -756,9 +756,9 @@ acpi_ds_load2_begin_op(struct acpi_walk_state *walk_state,
                 flags = ACPI_NS_NO_UPSEARCH;
                 if (walk_state->pass_number == 3) {
 
-                        /* Execution mode, node cannot already exist */
+                        /* Execution mode, node cannot already exist, node is temporary */
 
-                        flags |= ACPI_NS_ERROR_IF_FOUND;
+                        flags |= (ACPI_NS_ERROR_IF_FOUND | ACPI_NS_TEMPORARY);
                 }
 
                 /* Add new entry or lookup existing entry */
diff --git a/drivers/acpi/namespace/nsdump.c b/drivers/acpi/namespace/nsdump.c
index da88834f55e7..ec5ce59acb98 100644
--- a/drivers/acpi/namespace/nsdump.c
+++ b/drivers/acpi/namespace/nsdump.c
@@ -226,6 +226,12 @@ acpi_ns_dump_one_object(acpi_handle obj_handle,
         obj_desc = acpi_ns_get_attached_object(this_node);
         acpi_dbg_level = dbg_level;
 
+        /* Temp nodes are those nodes created by a control method */
+
+        if (this_node->flags & ANOBJ_TEMPORARY) {
+                acpi_os_printf("(T) ");
+        }
+
         switch (info->display_type & ACPI_DISPLAY_MASK) {
         case ACPI_DISPLAY_SUMMARY:
 
@@ -623,7 +629,8 @@ acpi_ns_dump_objects(acpi_object_type type,
         info.display_type = display_type;
 
         (void)acpi_ns_walk_namespace(type, start_handle, max_depth,
-                                     ACPI_NS_WALK_NO_UNLOCK,
+                                     ACPI_NS_WALK_NO_UNLOCK |
+                                     ACPI_NS_WALK_TEMP_NODES,
                                      acpi_ns_dump_one_object, (void *)&info,
                                      NULL);
 }
diff --git a/drivers/acpi/namespace/nssearch.c b/drivers/acpi/namespace/nssearch.c
index 566f0a4aff93..d261c9bcd450 100644
--- a/drivers/acpi/namespace/nssearch.c
+++ b/drivers/acpi/namespace/nssearch.c
@@ -402,6 +402,10 @@ acpi_ns_search_and_enter(u32 target_name,
         }
 #endif
 
+        if (flags & ACPI_NS_TEMPORARY) {
+                new_node->flags |= ANOBJ_TEMPORARY;
+        }
+
         /* Install the new object into the parent's list of children */
 
         acpi_ns_install_node(walk_state, node, new_node, type);
diff --git a/drivers/acpi/namespace/nswalk.c b/drivers/acpi/namespace/nswalk.c
index c8f6bef16ed0..a138fcb832a3 100644
--- a/drivers/acpi/namespace/nswalk.c
+++ b/drivers/acpi/namespace/nswalk.c
@@ -126,7 +126,7 @@ struct acpi_namespace_node *acpi_ns_get_next_node(acpi_object_type type,
  * PARAMETERS:  Type                - acpi_object_type to search for
  *              start_node          - Handle in namespace where search begins
  *              max_depth           - Depth to which search is to reach
- *              unlock_before_callback- Whether to unlock the NS before invoking
+ *              Flags               - Whether to unlock the NS before invoking
  *                                    the callback routine
  *              user_function       - Called when an object of "Type" is found
  *              Context             - Passed to user function
@@ -153,7 +153,7 @@ acpi_status
 acpi_ns_walk_namespace(acpi_object_type type,
                        acpi_handle start_node,
                        u32 max_depth,
-                       u8 unlock_before_callback,
+                       u32 flags,
                        acpi_walk_callback user_function,
                        void *context, void **return_value)
 {
@@ -201,12 +201,15 @@ acpi_ns_walk_namespace(acpi_object_type type,
                                 child_type = child_node->type;
                         }
 
-                        if (child_type == type) {
+                        if ((child_type == type) &&
+                            (!(child_node->flags & ANOBJ_TEMPORARY) ||
+                             (child_node->flags & ANOBJ_TEMPORARY)
+                             && (flags & ACPI_NS_WALK_TEMP_NODES))) {
                                 /*
                                  * Found a matching node, invoke the user
                                  * callback function
                                  */
-                                if (unlock_before_callback) {
+                                if (flags & ACPI_NS_WALK_UNLOCK) {
                                         mutex_status =
                                             acpi_ut_release_mutex
                                             (ACPI_MTX_NAMESPACE);
@@ -219,7 +222,7 @@ acpi_ns_walk_namespace(acpi_object_type type,
                                 status = user_function(child_node, level,
                                                        context, return_value);
 
-                                if (unlock_before_callback) {
+                                if (flags & ACPI_NS_WALK_UNLOCK) {
                                         mutex_status =
                                             acpi_ut_acquire_mutex
                                             (ACPI_MTX_NAMESPACE);