ACPICA: Mutex support: Fix release ordering issue and current sync level
Fixes a problem where if multiple mutexes of the same sync level
are acquired but then not released in strict opposite order, the
current sync level becomes confused and can cause errors.
ACPICA BZ 471.
http://acpica.org/bugzilla/show_bug.cgi?id=471
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>
diff --git a/drivers/acpi/acpica/exmutex.c b/drivers/acpi/acpica/exmutex.c
index d7cb030..77a592a 100644
--- a/drivers/acpi/acpica/exmutex.c
+++ b/drivers/acpi/acpica/exmutex.c
@@ -83,6 +83,15 @@
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 @@
struct acpi_walk_state *walk_state)
{
acpi_status status = AE_OK;
+ u8 previous_sync_level;
ACPI_FUNCTION_TRACE(ex_release_mutex);
@@ -404,14 +414,21 @@
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 (obj_desc->mutex.acquisition_depth == 0) {
/* Restore the original 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);
}