ACPICA: Ignore sync_level for methods that have been auto-serialized.

Cannot use a sync_level for methods that have been serialized at load-time
or runtime because this may interfere with any existing use of sync_levels
within the ASL code. So, we simply ignore the sync_level for these methods,
thus preserving any existing sync_level priorities. Note, the use of
sync_levels is actually rather rare within BIOS ASL code.

References: http://www.spinics.net/lists/linux-acpi/msg49496.html
Reported-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Reported-by: Sabrina Dubroka <sd@queasysnail.net>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

2 files changed, 21 insertions, 6 deletions

diff --git a/drivers/acpi/acpica/acobject.h b/drivers/acpi/acpica/acobject.h
index 1a4d61805ebc..22fb6449d3d6 100644
--- a/drivers/acpi/acpica/acobject.h
+++ b/drivers/acpi/acpica/acobject.h
@@ -193,7 +193,8 @@ struct acpi_object_method {
 #define ACPI_METHOD_INTERNAL_ONLY       0x02    /* Method is implemented internally (_OSI) */
 #define ACPI_METHOD_SERIALIZED          0x04    /* Method is serialized */
 #define ACPI_METHOD_SERIALIZED_PENDING  0x08    /* Method is to be marked serialized */
-#define ACPI_METHOD_MODIFIED_NAMESPACE  0x10    /* Method modified the namespace */
+#define ACPI_METHOD_IGNORE_SYNC_LEVEL   0x10    /* Method was auto-serialized at table load time */
+#define ACPI_METHOD_MODIFIED_NAMESPACE  0x20    /* Method modified the namespace */
 
 /******************************************************************************
  *
diff --git a/drivers/acpi/acpica/dsmethod.c b/drivers/acpi/acpica/dsmethod.c
index 73764c7d1c5d..3c7f7378b94d 100644
--- a/drivers/acpi/acpica/dsmethod.c
+++ b/drivers/acpi/acpica/dsmethod.c
@@ -175,8 +175,15 @@ acpi_ds_detect_named_opcodes(struct acpi_walk_state *walk_state,
          * At this point, we know we have a Named object opcode.
          * Mark the method as serialized. Later code will create a mutex for
          * this method to enforce serialization.
+         *
+         * Note, ACPI_METHOD_IGNORE_SYNC_LEVEL flag means that we will ignore the
+         * Sync Level mechanism for this method, even though it is now serialized.
+         * Otherwise, there can be conflicts with existing ASL code that actually
+         * uses sync levels.
          */
-        walk_state->method_desc->method.info_flags |= ACPI_METHOD_SERIALIZED;
+        walk_state->method_desc->method.sync_level = 0;
+        walk_state->method_desc->method.info_flags |=
+            (ACPI_METHOD_SERIALIZED | ACPI_METHOD_IGNORE_SYNC_LEVEL);
 
         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                           "Method serialized [%4.4s] %p - [%s] (%4.4X)\n",
@@ -349,13 +356,19 @@ acpi_ds_begin_method_execution(struct acpi_namespace_node *method_node,
                 /*
                  * The current_sync_level (per-thread) must be less than or equal to
                  * the sync level of the method. This mechanism provides some
-                 * deadlock prevention
+                 * deadlock prevention.
+                 *
+                 * If the method was auto-serialized, we just ignore the sync level
+                 * mechanism, because auto-serialization of methods can interfere
+                 * with ASL code that actually uses sync levels.
                  *
                  * Top-level method invocation has no walk state at this point
                  */
                 if (walk_state &&
-                    (walk_state->thread->current_sync_level >
-                     obj_desc->method.mutex->mutex.sync_level)) {
+                    (!(obj_desc->method.
+                       info_flags & ACPI_METHOD_IGNORE_SYNC_LEVEL))
+                    && (walk_state->thread->current_sync_level >
+                        obj_desc->method.mutex->mutex.sync_level)) {
                         ACPI_ERROR((AE_INFO,
                                     "Cannot acquire Mutex for method [%4.4s], current SyncLevel is too large (%u)",
                                     acpi_ut_get_node_name(method_node),
@@ -800,7 +813,8 @@ acpi_ds_terminate_control_method(union acpi_operand_object *method_desc,
                         method_desc->method.info_flags &=
                             ~ACPI_METHOD_SERIALIZED_PENDING;
                         method_desc->method.info_flags |=
-                            ACPI_METHOD_SERIALIZED;
+                            (ACPI_METHOD_SERIALIZED |
+                             ACPI_METHOD_IGNORE_SYNC_LEVEL);
                         method_desc->method.sync_level = 0;
                 }