1 files changed, 35 insertions, 10 deletions

diff --git a/drivers/acpi/acpica/exmutex.c b/drivers/acpi/acpica/exmutex.c
index d301c1f363ef..2f0114202b05 100644
--- a/drivers/acpi/acpica/exmutex.c
+++ b/drivers/acpi/acpica/exmutex.c
@@ -83,6 +83,15 @@ void acpi_ex_unlink_mutex(union acpi_operand_object *obj_desc)
 
         if (obj_desc->mutex.prev) {
                 (obj_desc->mutex.prev)->mutex.next = obj_desc->mutex.next;
+
+                /*
+                 * Migrate the previous sync level associated with this mutex to the
+                 * previous mutex on the list so that it may be preserved. This handles
+                 * the case where several mutexes have been acquired at the same level,
+                 * but are not released in opposite order.
+                 */
+                (obj_desc->mutex.prev)->mutex.original_sync_level =
+                    obj_desc->mutex.original_sync_level;
         } else {
                 thread->acquired_mutex_list = obj_desc->mutex.next;
         }
@@ -349,6 +358,7 @@ acpi_ex_release_mutex(union acpi_operand_object *obj_desc,
                       struct acpi_walk_state *walk_state)
 {
         acpi_status status = AE_OK;
+        u8 previous_sync_level;
 
         ACPI_FUNCTION_TRACE(ex_release_mutex);
 
@@ -373,11 +383,12 @@ acpi_ex_release_mutex(union acpi_operand_object *obj_desc,
              walk_state->thread->thread_id)
             && (obj_desc != acpi_gbl_global_lock_mutex)) {
                 ACPI_ERROR((AE_INFO,
-                            "Thread %lX cannot release Mutex [%4.4s] acquired by thread %lX",
-                            (unsigned long)walk_state->thread->thread_id,
+                            "Thread %p cannot release Mutex [%4.4s] acquired by thread %p",
+                            ACPI_CAST_PTR(void, walk_state->thread->thread_id),
                             acpi_ut_get_node_name(obj_desc->mutex.node),
-                            (unsigned long)obj_desc->mutex.owner_thread->
-                            thread_id));
+                            ACPI_CAST_PTR(void,
+                                          obj_desc->mutex.owner_thread->
+                                          thread_id)));
                 return_ACPI_STATUS(AE_AML_NOT_OWNER);
         }
 
@@ -391,10 +402,14 @@ acpi_ex_release_mutex(union acpi_operand_object *obj_desc,
         }
 
         /*
-         * The sync level of the mutex must be less than or equal to the current
-         * sync level
+         * The sync level of the mutex must be equal to the current sync level. In
+         * other words, the current level means that at least one mutex at that
+         * level is currently being held. Attempting to release a mutex of a
+         * different level can only mean that the mutex ordering rule is being
+         * violated. This behavior is clarified in ACPI 4.0 specification.
          */
-        if (obj_desc->mutex.sync_level > walk_state->thread->current_sync_level) {
+        if (obj_desc->mutex.sync_level !=
+            walk_state->thread->current_sync_level) {
                 ACPI_ERROR((AE_INFO,
                             "Cannot release Mutex [%4.4s], SyncLevel mismatch: mutex %d current %d",
                             acpi_ut_get_node_name(obj_desc->mutex.node),
@@ -403,14 +418,24 @@ acpi_ex_release_mutex(union acpi_operand_object *obj_desc,
                 return_ACPI_STATUS(AE_AML_MUTEX_ORDER);
         }
 
+        /*
+         * Get the previous sync_level from the head of the acquired mutex list.
+         * This handles the case where several mutexes at the same level have been
+         * acquired, but are not released in reverse order.
+         */
+        previous_sync_level =
+            walk_state->thread->acquired_mutex_list->mutex.original_sync_level;
+
         status = acpi_ex_release_mutex_object(obj_desc);
+        if (ACPI_FAILURE(status)) {
+                return_ACPI_STATUS(status);
+        }
 
         if (obj_desc->mutex.acquisition_depth == 0) {
 
-                /* Restore the original sync_level */
+                /* Restore the previous sync_level */
 
-                walk_state->thread->current_sync_level =
-                    obj_desc->mutex.original_sync_level;
+                walk_state->thread->current_sync_level = previous_sync_level;
         }
         return_ACPI_STATUS(status);
 }