diff --git a/services/audioflinger/AudioFlinger.cpp b/services/audioflinger/AudioFlinger.cpp
index b972548..3b531bc 100644
--- a/services/audioflinger/AudioFlinger.cpp
+++ b/services/audioflinger/AudioFlinger.cpp
@@ -2067,9 +2067,7 @@
                 maxPeriod = seconds(mFrameCount) / mSampleRate * 15;
 }
 
-if (mType == DUPLICATING) {
-                updateWaitTime();
-}
+                updateWaitTime_l();
 
                 activeSleepTime = activeSleepTimeUs();
                 idleSleepTime = idleSleepTimeUs();
@@ -3202,7 +3200,7 @@
         thread->setStreamVolume(AUDIO_STREAM_CNT, 1.0f);
         mOutputTracks.add(outputTrack);
         ALOGV("addOutputTrack() track %p, on thread %p", outputTrack, thread);
-        updateWaitTime();
+        updateWaitTime_l();
     }
 }
 
@@ -3213,14 +3211,15 @@
         if (mOutputTracks[i]->thread() == thread) {
             mOutputTracks[i]->destroy();
             mOutputTracks.removeAt(i);
-            updateWaitTime();
+            updateWaitTime_l();
             return;
         }
     }
     ALOGV("removeOutputTrack(): unkonwn thread: %p", thread);
 }
 
-void AudioFlinger::DuplicatingThread::updateWaitTime()
+// caller must hold mLock
+void AudioFlinger::DuplicatingThread::updateWaitTime_l()
 {
     mWaitTimeMs = UINT_MAX;
     for (size_t i = 0; i < mOutputTracks.size(); i++) {
diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index c7ac0a8..28b33a2 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -812,7 +812,7 @@
         virtual     void        threadLoop_standby();
 
         // Non-trivial for DUPLICATING only
-        virtual     void        updateWaitTime() { }
+        virtual     void        updateWaitTime_l() { }
 
         // Non-trivial for DIRECT only
         virtual     void        applyVolume() { }
@@ -1046,7 +1046,9 @@
         virtual     void        threadLoop_sleepTime();
         virtual     void        threadLoop_write();
         virtual     void        threadLoop_standby();
-        virtual     void        updateWaitTime();
+
+        // called from threadLoop, addOutputTrack, removeOutputTrack
+        virtual     void        updateWaitTime_l();
     private:
 
                     uint32_t    mWaitTimeMs;