diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index 13ca912..01c5ea2 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -2794,22 +2794,18 @@
 void AudioFlinger::PlaybackThread::threadLoop_removeTracks(
         const Vector< sp<Track> >& tracksToRemove)
 {
-    size_t count = tracksToRemove.size();
-    if (count > 0) {
-        for (size_t i = 0 ; i < count ; i++) {
-            const sp<Track>& track = tracksToRemove.itemAt(i);
-            if (track->isExternalTrack()) {
-                AudioSystem::stopOutput(track->portId());
+    // Miscellaneous track cleanup when removed from the active list,
+    // called without Thread lock but synchronized with threadLoop processing.
 #ifdef ADD_BATTERY_DATA
-                // to track the speaker usage
-                addBatteryData(IMediaPlayerService::kBatteryDataAudioFlingerStop);
-#endif
-                if (track->isTerminated()) {
-                    AudioSystem::releaseOutput(track->portId());
-                }
-            }
+    for (const auto& track : tracksToRemove) {
+        if (track->isExternalTrack()) {
+            // to track the speaker usage
+            addBatteryData(IMediaPlayerService::kBatteryDataAudioFlingerStop);
         }
     }
+#else
+    (void)tracksToRemove; // suppress unused warning
+#endif
 }
 
 void AudioFlinger::PlaybackThread::checkSilentMode_l()
@@ -3710,24 +3706,28 @@
 // removeTracks_l() must be called with ThreadBase::mLock held
 void AudioFlinger::PlaybackThread::removeTracks_l(const Vector< sp<Track> >& tracksToRemove)
 {
-    size_t count = tracksToRemove.size();
-    if (count > 0) {
-        for (size_t i=0 ; i<count ; i++) {
-            const sp<Track>& track = tracksToRemove.itemAt(i);
-            mActiveTracks.remove(track);
-            ALOGV("removeTracks_l removing track on session %d", track->sessionId());
-            sp<EffectChain> chain = getEffectChain_l(track->sessionId());
-            if (chain != 0) {
-                ALOGV("stopping track on chain %p for session Id: %d", chain.get(),
-                        track->sessionId());
-                chain->decActiveTrackCnt();
-            }
+    for (const auto& track : tracksToRemove) {
+        mActiveTracks.remove(track);
+        ALOGV("%s(%d): removing track on session %d", __func__, track->id(), track->sessionId());
+        sp<EffectChain> chain = getEffectChain_l(track->sessionId());
+        if (chain != 0) {
+            ALOGV("%s(%d): stopping track on chain %p for session Id: %d",
+                    __func__, track->id(), chain.get(), track->sessionId());
+            chain->decActiveTrackCnt();
+        }
+        // If an external client track, inform APM we're no longer active, and remove if needed.
+        // We do this under lock so that the state is consistent if the Track is destroyed.
+        if (track->isExternalTrack()) {
+            AudioSystem::stopOutput(track->portId());
             if (track->isTerminated()) {
-                removeTrack_l(track);
+                AudioSystem::releaseOutput(track->portId());
             }
         }
+        if (track->isTerminated()) {
+            // remove from our tracks vector
+            removeTrack_l(track);
+        }
     }
-
 }
 
 status_t AudioFlinger::PlaybackThread::getTimestamp_l(AudioTimestamp& timestamp)
@@ -4115,12 +4115,6 @@
     return latency;
 }
 
-
-void AudioFlinger::MixerThread::threadLoop_removeTracks(const Vector< sp<Track> >& tracksToRemove)
-{
-    PlaybackThread::threadLoop_removeTracks(tracksToRemove);
-}
-
 ssize_t AudioFlinger::MixerThread::threadLoop_write()
 {
     // FIXME we should only do one push per cycle; confirm this is true
diff --git a/services/audioflinger/Threads.h b/services/audioflinger/Threads.h
index 88c6ff3..61f7baf 100644
--- a/services/audioflinger/Threads.h
+++ b/services/audioflinger/Threads.h
@@ -1137,7 +1137,6 @@
     virtual     void        threadLoop_standby();
     virtual     void        threadLoop_mix();
     virtual     void        threadLoop_sleepTime();
-    virtual     void        threadLoop_removeTracks(const Vector< sp<Track> >& tracksToRemove);
     virtual     uint32_t    correctLatency_l(uint32_t latency) const;
 
     virtual     status_t    createAudioPatch_l(const struct audio_patch *patch,
diff --git a/services/audiopolicy/service/AudioPolicyService.cpp b/services/audiopolicy/service/AudioPolicyService.cpp
index 8bca221..b1ed522 100644
--- a/services/audiopolicy/service/AudioPolicyService.cpp
+++ b/services/audiopolicy/service/AudioPolicyService.cpp
@@ -677,21 +677,27 @@
                     VolumeData *data = (VolumeData *)command->mParam.get();
                     ALOGV("AudioCommandThread() processing set volume stream %d, \
                             volume %f, output %d", data->mStream, data->mVolume, data->mIO);
+                    mLock.unlock();
                     command->mStatus = AudioSystem::setStreamVolume(data->mStream,
                                                                     data->mVolume,
                                                                     data->mIO);
+                    mLock.lock();
                     }break;
                 case SET_PARAMETERS: {
                     ParametersData *data = (ParametersData *)command->mParam.get();
                     ALOGV("AudioCommandThread() processing set parameters string %s, io %d",
                             data->mKeyValuePairs.string(), data->mIO);
+                    mLock.unlock();
                     command->mStatus = AudioSystem::setParameters(data->mIO, data->mKeyValuePairs);
+                    mLock.lock();
                     }break;
                 case SET_VOICE_VOLUME: {
                     VoiceVolumeData *data = (VoiceVolumeData *)command->mParam.get();
                     ALOGV("AudioCommandThread() processing set voice volume volume %f",
                             data->mVolume);
+                    mLock.unlock();
                     command->mStatus = AudioSystem::setVoiceVolume(data->mVolume);
+                    mLock.lock();
                     }break;
                 case STOP_OUTPUT: {
                     StopOutputData *data = (StopOutputData *)command->mParam.get();
@@ -724,7 +730,9 @@
                     if (af == 0) {
                         command->mStatus = PERMISSION_DENIED;
                     } else {
+                        mLock.unlock();
                         command->mStatus = af->createAudioPatch(&data->mPatch, &data->mHandle);
+                        mLock.lock();
                     }
                     } break;
                 case RELEASE_AUDIO_PATCH: {
@@ -734,7 +742,9 @@
                     if (af == 0) {
                         command->mStatus = PERMISSION_DENIED;
                     } else {
+                        mLock.unlock();
                         command->mStatus = af->releaseAudioPatch(data->mHandle);
+                        mLock.lock();
                     }
                     } break;
                 case UPDATE_AUDIOPORT_LIST: {
@@ -764,7 +774,9 @@
                     if (af == 0) {
                         command->mStatus = PERMISSION_DENIED;
                     } else {
+                        mLock.unlock();
                         command->mStatus = af->setAudioPortConfig(&data->mConfig);
+                        mLock.lock();
                     }
                     } break;
                 case DYN_POLICY_MIX_STATE_UPDATE: {