diff --git a/services/audioflinger/Threads.h b/services/audioflinger/Threads.h
index 7de6872..e15d98a 100644
--- a/services/audioflinger/Threads.h
+++ b/services/audioflinger/Threads.h
@@ -429,6 +429,8 @@
 
                 virtual status_t setSyncEvent(const sp<SyncEvent>& event);
                 virtual bool     isValidSyncEvent(const sp<SyncEvent>& event) const;
+
+                // called with AudioFlinger lock held
                         void     invalidateTracks(audio_stream_type_t streamType);