diff --git a/services/audiopolicy/AudioPolicyEffects.cpp b/services/audiopolicy/AudioPolicyEffects.cpp
index c45acd0..3c1c042 100644
--- a/services/audiopolicy/AudioPolicyEffects.cpp
+++ b/services/audiopolicy/AudioPolicyEffects.cpp
@@ -87,6 +87,7 @@
     audio_source_t aliasSource = (inputSource == AUDIO_SOURCE_HOTWORD) ?
                                     AUDIO_SOURCE_VOICE_RECOGNITION : inputSource;
 
+    Mutex::Autolock _l(mLock);
     ssize_t index = mInputSources.indexOfKey(aliasSource);
     if (index < 0) {
         ALOGV("addInputEffects(): no processing needs to be attached to this source");
@@ -122,7 +123,7 @@
         ALOGV("addInputEffects(): added Fx %s on source: %d", effect->mName, (int32_t)aliasSource);
         inputDesc->mEffects.add(fx);
     }
-    setProcessorEnabled(inputDesc, true);
+    inputDesc->setProcessorEnabled(true);
 
     return status;
 }
@@ -132,6 +133,7 @@
 {
     status_t status = NO_ERROR;
 
+    Mutex::Autolock _l(mLock);
     ssize_t index = mInputs.indexOfKey(input);
     if (index < 0) {
         return status;
@@ -140,7 +142,7 @@
     inputDesc->mRefCount--;
     ALOGV("releaseInputEffects(): input: %d, refCount: %d", input, inputDesc->mRefCount);
     if (inputDesc->mRefCount == 0) {
-        setProcessorEnabled(inputDesc, false);
+        inputDesc->setProcessorEnabled(false);
         delete inputDesc;
         mInputs.removeItemsAt(index);
         ALOGV("releaseInputEffects(): all effects released");
@@ -154,6 +156,7 @@
 {
     status_t status = NO_ERROR;
 
+    Mutex::Autolock _l(mLock);
     size_t index;
     for (index = 0; index < mInputs.size(); index++) {
         if (mInputs.valueAt(index)->mSessionId == audioSession) {
@@ -186,6 +189,7 @@
 {
     status_t status = NO_ERROR;
 
+    Mutex::Autolock _l(mLock);
     size_t index;
     for (index = 0; index < mOutputSessions.size(); index++) {
         if (mOutputSessions.valueAt(index)->mSessionId == audioSession) {
@@ -218,6 +222,7 @@
 {
     status_t status = NO_ERROR;
 
+    Mutex::Autolock _l(mLock);
     // create audio processors according to stream
     ssize_t index = mOutputStreams.indexOfKey(stream);
     if (index < 0) {
@@ -254,7 +259,7 @@
         procDesc->mEffects.add(fx);
     }
 
-    setProcessorEnabled(procDesc, true);
+    procDesc->setProcessorEnabled(true);
 
     return status;
 }
@@ -267,6 +272,7 @@
     (void) output; // argument not used for now
     (void) stream; // argument not used for now
 
+    Mutex::Autolock _l(mLock);
     ssize_t index = mOutputSessions.indexOfKey(audioSession);
     if (index < 0) {
         ALOGV("releaseOutputSessionEffects: no output processing was attached to this stream");
@@ -277,7 +283,7 @@
     procDesc->mRefCount--;
     ALOGV("releaseOutputSessionEffects(): session: %d, refCount: %d", audioSession, procDesc->mRefCount);
     if (procDesc->mRefCount == 0) {
-        setProcessorEnabled(procDesc, false);
+        procDesc->setProcessorEnabled(false);
         procDesc->mEffects.clear();
         delete procDesc;
         mOutputSessions.removeItemsAt(index);
@@ -288,11 +294,10 @@
 }
 
 
-void AudioPolicyEffects::setProcessorEnabled(const EffectVector *effectVector, bool enabled)
+void AudioPolicyEffects::EffectVector::setProcessorEnabled(bool enabled)
 {
-    const Vector<sp<AudioEffect> > &fxVector = effectVector->mEffects;
-    for (size_t i = 0; i < fxVector.size(); i++) {
-        fxVector.itemAt(i)->setEnabled(enabled);
+    for (size_t i = 0; i < mEffects.size(); i++) {
+        mEffects.itemAt(i)->setEnabled(enabled);
     }
 }
 
@@ -313,7 +318,7 @@
 
 // returns the audio_source_t enum corresponding to the input source name or
 // AUDIO_SOURCE_CNT is no match found
-audio_source_t AudioPolicyEffects::inputSourceNameToEnum(const char *name)
+/*static*/ audio_source_t AudioPolicyEffects::inputSourceNameToEnum(const char *name)
 {
     int i;
     for (i = AUDIO_SOURCE_MIC; i < AUDIO_SOURCE_CNT; i++) {
diff --git a/services/audiopolicy/AudioPolicyEffects.h b/services/audiopolicy/AudioPolicyEffects.h
index dbe0d0e..6b0d538 100644
--- a/services/audiopolicy/AudioPolicyEffects.h
+++ b/services/audiopolicy/AudioPolicyEffects.h
@@ -45,6 +45,10 @@
 	         AudioPolicyEffects();
     virtual ~AudioPolicyEffects();
 
+    // NOTE: methods on AudioPolicyEffects should never be called with the AudioPolicyService
+    // main mutex (mLock) held as they will indirectly call back into AudioPolicyService when
+    // managing audio effects.
+
     // Return a list of effect descriptors for default input effects
     // associated with audioSession
     status_t queryDefaultInputEffects(int audioSession,
@@ -133,6 +137,10 @@
     public:
         EffectVector(int session) : mSessionId(session), mRefCount(0) {}
         /*virtual*/ ~EffectVector() {}
+
+        // Enable or disable all effects in effect vector
+        void setProcessorEnabled(bool enabled);
+
         const int mSessionId;
         // AudioPolicyManager keeps mLock, no need for lock on reference count here
         int mRefCount;
@@ -141,14 +149,11 @@
 
 
     static const char * const kInputSourceNames[AUDIO_SOURCE_CNT -1];
-    audio_source_t inputSourceNameToEnum(const char *name);
+    static audio_source_t inputSourceNameToEnum(const char *name);
 
     static const char *kStreamNames[AUDIO_STREAM_CNT+1]; //+1 required as streams start from -1
     audio_stream_type_t streamNameToEnum(const char *name);
 
-    // Enable or disable all effects in effect vector
-    void setProcessorEnabled(const EffectVector *effectVector, bool enabled);
-
     // Parse audio_effects.conf
     status_t loadAudioEffectConfig(const char *path);
 
@@ -173,6 +178,8 @@
                          size_t *curSize,
                          size_t *totSize);
 
+    // protects access to mInputSources, mInputs, mOutputStreams, mOutputSessions
+    Mutex mLock;
     // Automatic input effects are configured per audio_source_t
     KeyedVector< audio_source_t, EffectDescVector* > mInputSources;
     // Automatic input effects are unique for audio_io_handle_t
diff --git a/services/audiopolicy/AudioPolicyInterfaceImpl.cpp b/services/audiopolicy/AudioPolicyInterfaceImpl.cpp
index b212ca6..6cd0ac8 100644
--- a/services/audiopolicy/AudioPolicyInterfaceImpl.cpp
+++ b/services/audiopolicy/AudioPolicyInterfaceImpl.cpp
@@ -162,14 +162,19 @@
         return NO_INIT;
     }
     ALOGV("startOutput()");
-    Mutex::Autolock _l(mLock);
-
-    // create audio processors according to stream
-    status_t status = mAudioPolicyEffects->addOutputSessionEffects(output, stream, session);
-    if (status != NO_ERROR && status != ALREADY_EXISTS) {
-        ALOGW("Failed to add effects on session %d", session);
+    sp<AudioPolicyEffects>audioPolicyEffects;
+    {
+        Mutex::Autolock _l(mLock);
+        audioPolicyEffects = mAudioPolicyEffects;
     }
-
+    if (audioPolicyEffects != 0) {
+        // create audio processors according to stream
+        status_t status = audioPolicyEffects->addOutputSessionEffects(output, stream, session);
+        if (status != NO_ERROR && status != ALREADY_EXISTS) {
+            ALOGW("Failed to add effects on session %d", session);
+        }
+    }
+    Mutex::Autolock _l(mLock);
     return mAudioPolicyManager->startOutput(output, stream, session);
 }
 
@@ -190,14 +195,19 @@
                                       int session)
 {
     ALOGV("doStopOutput from tid %d", gettid());
-    Mutex::Autolock _l(mLock);
-
-    // release audio processors from the stream
-    status_t status = mAudioPolicyEffects->releaseOutputSessionEffects(output, stream, session);
-    if (status != NO_ERROR && status != ALREADY_EXISTS) {
-        ALOGW("Failed to release effects on session %d", session);
+    sp<AudioPolicyEffects>audioPolicyEffects;
+    {
+        Mutex::Autolock _l(mLock);
+        audioPolicyEffects = mAudioPolicyEffects;
     }
-
+    if (audioPolicyEffects != 0) {
+        // release audio processors from the stream
+        status_t status = audioPolicyEffects->releaseOutputSessionEffects(output, stream, session);
+        if (status != NO_ERROR && status != ALREADY_EXISTS) {
+            ALOGW("Failed to release effects on session %d", session);
+        }
+    }
+    Mutex::Autolock _l(mLock);
     return mAudioPolicyManager->stopOutput(output, stream, session);
 }
 
@@ -235,23 +245,26 @@
     if ((inputSource == AUDIO_SOURCE_HOTWORD) && !captureHotwordAllowed()) {
         return 0;
     }
-
-    Mutex::Autolock _l(mLock);
-    // the audio_in_acoustics_t parameter is ignored by get_input()
-    audio_io_handle_t input = mAudioPolicyManager->getInput(inputSource, samplingRate,
-                                                   format, channelMask,
-                                                   (audio_session_t)audioSession, flags);
-
+    audio_io_handle_t input;
+    sp<AudioPolicyEffects>audioPolicyEffects;
+    {
+        Mutex::Autolock _l(mLock);
+        // the audio_in_acoustics_t parameter is ignored by get_input()
+        input = mAudioPolicyManager->getInput(inputSource, samplingRate,
+                                                       format, channelMask,
+                                                       (audio_session_t)audioSession, flags);
+        audioPolicyEffects = mAudioPolicyEffects;
+    }
     if (input == 0) {
         return input;
     }
-
-    // create audio pre processors according to input source
-    status_t status = mAudioPolicyEffects->addInputEffects(input, inputSource, audioSession);
-    if (status != NO_ERROR && status != ALREADY_EXISTS) {
-        ALOGW("Failed to add effects on input %d", input);
+    if (audioPolicyEffects != 0) {
+        // create audio pre processors according to input source
+        status_t status = audioPolicyEffects->addInputEffects(input, inputSource, audioSession);
+        if (status != NO_ERROR && status != ALREADY_EXISTS) {
+            ALOGW("Failed to add effects on input %d", input);
+        }
     }
-
     return input;
 }
 
@@ -283,13 +296,18 @@
     if (mAudioPolicyManager == NULL) {
         return;
     }
-    Mutex::Autolock _l(mLock);
-    mAudioPolicyManager->releaseInput(input, session);
-
-    // release audio processors from the input
-    status_t status = mAudioPolicyEffects->releaseInputEffects(input);
-    if(status != NO_ERROR) {
-        ALOGW("Failed to release effects on input %d", input);
+    sp<AudioPolicyEffects>audioPolicyEffects;
+    {
+        Mutex::Autolock _l(mLock);
+        mAudioPolicyManager->releaseInput(input, session);
+        audioPolicyEffects = mAudioPolicyEffects;
+    }
+    if (audioPolicyEffects != 0) {
+        // release audio processors from the input
+        status_t status = audioPolicyEffects->releaseInputEffects(input);
+        if(status != NO_ERROR) {
+            ALOGW("Failed to release effects on input %d", input);
+        }
     }
 }
 
@@ -437,9 +455,16 @@
         *count = 0;
         return NO_INIT;
     }
-    Mutex::Autolock _l(mLock);
-
-    return mAudioPolicyEffects->queryDefaultInputEffects(audioSession, descriptors, count);
+    sp<AudioPolicyEffects>audioPolicyEffects;
+    {
+        Mutex::Autolock _l(mLock);
+        audioPolicyEffects = mAudioPolicyEffects;
+    }
+    if (audioPolicyEffects == 0) {
+        *count = 0;
+        return NO_INIT;
+    }
+    return audioPolicyEffects->queryDefaultInputEffects(audioSession, descriptors, count);
 }
 
 bool AudioPolicyService::isOffloadSupported(const audio_offload_info_t& info)
diff --git a/services/audiopolicy/AudioPolicyInterfaceImplLegacy.cpp b/services/audiopolicy/AudioPolicyInterfaceImplLegacy.cpp
index 1e40bc3..9f66fd1 100644
--- a/services/audiopolicy/AudioPolicyInterfaceImplLegacy.cpp
+++ b/services/audiopolicy/AudioPolicyInterfaceImplLegacy.cpp
@@ -150,14 +150,20 @@
         return NO_INIT;
     }
     ALOGV("startOutput()");
-    Mutex::Autolock _l(mLock);
-
     // create audio processors according to stream
-    status_t status = mAudioPolicyEffects->addOutputSessionEffects(output, stream, session);
-    if (status != NO_ERROR && status != ALREADY_EXISTS) {
-        ALOGW("Failed to add effects on session %d", session);
+    sp<AudioPolicyEffects>audioPolicyEffects;
+    {
+        Mutex::Autolock _l(mLock);
+        audioPolicyEffects = mAudioPolicyEffects;
+    }
+    if (audioPolicyEffects != 0) {
+        status_t status = audioPolicyEffects->addOutputSessionEffects(output, stream, session);
+        if (status != NO_ERROR && status != ALREADY_EXISTS) {
+            ALOGW("Failed to add effects on session %d", session);
+        }
     }
 
+    Mutex::Autolock _l(mLock);
     return mpAudioPolicy->start_output(mpAudioPolicy, output, stream, session);
 }
 
@@ -178,14 +184,19 @@
                                       int session)
 {
     ALOGV("doStopOutput from tid %d", gettid());
-    Mutex::Autolock _l(mLock);
-
     // release audio processors from the stream
-    status_t status = mAudioPolicyEffects->releaseOutputSessionEffects(output, stream, session);
-    if (status != NO_ERROR && status != ALREADY_EXISTS) {
-        ALOGW("Failed to release effects on session %d", session);
+    sp<AudioPolicyEffects>audioPolicyEffects;
+    {
+        Mutex::Autolock _l(mLock);
+        audioPolicyEffects = mAudioPolicyEffects;
     }
-
+    if (audioPolicyEffects != 0) {
+        status_t status = audioPolicyEffects->releaseOutputSessionEffects(output, stream, session);
+        if (status != NO_ERROR && status != ALREADY_EXISTS) {
+            ALOGW("Failed to release effects on session %d", session);
+        }
+    }
+    Mutex::Autolock _l(mLock);
     return mpAudioPolicy->stop_output(mpAudioPolicy, output, stream, session);
 }
 
@@ -224,21 +235,26 @@
         return 0;
     }
 
-    Mutex::Autolock _l(mLock);
-    // the audio_in_acoustics_t parameter is ignored by get_input()
-    audio_io_handle_t input = mpAudioPolicy->get_input(mpAudioPolicy, inputSource, samplingRate,
-                                                   format, channelMask, (audio_in_acoustics_t) 0);
-
+    audio_io_handle_t input;
+    sp<AudioPolicyEffects>audioPolicyEffects;
+    {
+        Mutex::Autolock _l(mLock);
+        // the audio_in_acoustics_t parameter is ignored by get_input()
+        input = mpAudioPolicy->get_input(mpAudioPolicy, inputSource, samplingRate,
+                                             format, channelMask, (audio_in_acoustics_t) 0);
+        audioPolicyEffects = mAudioPolicyEffects;
+    }
     if (input == 0) {
         return input;
     }
 
-    // create audio pre processors according to input source
-    status_t status = mAudioPolicyEffects->addInputEffects(input, inputSource, audioSession);
-    if (status != NO_ERROR && status != ALREADY_EXISTS) {
-        ALOGW("Failed to add effects on input %d", input);
+    if (audioPolicyEffects != 0) {
+        // create audio pre processors according to input source
+        status_t status = audioPolicyEffects->addInputEffects(input, inputSource, audioSession);
+        if (status != NO_ERROR && status != ALREADY_EXISTS) {
+            ALOGW("Failed to add effects on input %d", input);
+        }
     }
-
     return input;
 }
 
@@ -270,13 +286,19 @@
     if (mpAudioPolicy == NULL) {
         return;
     }
-    Mutex::Autolock _l(mLock);
-    mpAudioPolicy->release_input(mpAudioPolicy, input);
 
-    // release audio processors from the input
-    status_t status = mAudioPolicyEffects->releaseInputEffects(input);
-    if(status != NO_ERROR) {
-        ALOGW("Failed to release effects on input %d", input);
+    sp<AudioPolicyEffects>audioPolicyEffects;
+    {
+        Mutex::Autolock _l(mLock);
+        mpAudioPolicy->release_input(mpAudioPolicy, input);
+        audioPolicyEffects = mAudioPolicyEffects;
+    }
+    if (audioPolicyEffects != 0) {
+        // release audio processors from the input
+        status_t status = audioPolicyEffects->releaseInputEffects(input);
+        if(status != NO_ERROR) {
+            ALOGW("Failed to release effects on input %d", input);
+        }
     }
 }
 
@@ -437,9 +459,16 @@
         *count = 0;
         return NO_INIT;
     }
-    Mutex::Autolock _l(mLock);
-
-    return mAudioPolicyEffects->queryDefaultInputEffects(audioSession, descriptors, count);
+    sp<AudioPolicyEffects>audioPolicyEffects;
+    {
+        Mutex::Autolock _l(mLock);
+        audioPolicyEffects = mAudioPolicyEffects;
+    }
+    if (audioPolicyEffects == 0) {
+        *count = 0;
+        return NO_INIT;
+    }
+    return audioPolicyEffects->queryDefaultInputEffects(audioSession, descriptors, count);
 }
 
 bool AudioPolicyService::isOffloadSupported(const audio_offload_info_t& info)
diff --git a/services/audiopolicy/AudioPolicyService.cpp b/services/audiopolicy/AudioPolicyService.cpp
index 647cda4..4761a13 100644
--- a/services/audiopolicy/AudioPolicyService.cpp
+++ b/services/audiopolicy/AudioPolicyService.cpp
@@ -66,51 +66,56 @@
     int forced_val;
     int rc;
 
-    Mutex::Autolock _l(mLock);
+    {
+        Mutex::Autolock _l(mLock);
 
-    // start tone playback thread
-    mTonePlaybackThread = new AudioCommandThread(String8("ApmTone"), this);
-    // start audio commands thread
-    mAudioCommandThread = new AudioCommandThread(String8("ApmAudio"), this);
-    // start output activity command thread
-    mOutputCommandThread = new AudioCommandThread(String8("ApmOutput"), this);
+        // start tone playback thread
+        mTonePlaybackThread = new AudioCommandThread(String8("ApmTone"), this);
+        // start audio commands thread
+        mAudioCommandThread = new AudioCommandThread(String8("ApmAudio"), this);
+        // start output activity command thread
+        mOutputCommandThread = new AudioCommandThread(String8("ApmOutput"), this);
 
 #ifdef USE_LEGACY_AUDIO_POLICY
-    ALOGI("AudioPolicyService CSTOR in legacy mode");
+        ALOGI("AudioPolicyService CSTOR in legacy mode");
 
-    /* instantiate the audio policy manager */
-    rc = hw_get_module(AUDIO_POLICY_HARDWARE_MODULE_ID, &module);
-    if (rc) {
-        return;
-    }
-    rc = audio_policy_dev_open(module, &mpAudioPolicyDev);
-    ALOGE_IF(rc, "couldn't open audio policy device (%s)", strerror(-rc));
-    if (rc) {
-        return;
-    }
+        /* instantiate the audio policy manager */
+        rc = hw_get_module(AUDIO_POLICY_HARDWARE_MODULE_ID, &module);
+        if (rc) {
+            return;
+        }
+        rc = audio_policy_dev_open(module, &mpAudioPolicyDev);
+        ALOGE_IF(rc, "couldn't open audio policy device (%s)", strerror(-rc));
+        if (rc) {
+            return;
+        }
 
-    rc = mpAudioPolicyDev->create_audio_policy(mpAudioPolicyDev, &aps_ops, this,
-                                               &mpAudioPolicy);
-    ALOGE_IF(rc, "couldn't create audio policy (%s)", strerror(-rc));
-    if (rc) {
-        return;
-    }
+        rc = mpAudioPolicyDev->create_audio_policy(mpAudioPolicyDev, &aps_ops, this,
+                                                   &mpAudioPolicy);
+        ALOGE_IF(rc, "couldn't create audio policy (%s)", strerror(-rc));
+        if (rc) {
+            return;
+        }
 
-    rc = mpAudioPolicy->init_check(mpAudioPolicy);
-    ALOGE_IF(rc, "couldn't init_check the audio policy (%s)", strerror(-rc));
-    if (rc) {
-        return;
-    }
-    ALOGI("Loaded audio policy from %s (%s)", module->name, module->id);
+        rc = mpAudioPolicy->init_check(mpAudioPolicy);
+        ALOGE_IF(rc, "couldn't init_check the audio policy (%s)", strerror(-rc));
+        if (rc) {
+            return;
+        }
+        ALOGI("Loaded audio policy from %s (%s)", module->name, module->id);
 #else
-    ALOGI("AudioPolicyService CSTOR in new mode");
+        ALOGI("AudioPolicyService CSTOR in new mode");
 
-    mAudioPolicyClient = new AudioPolicyClient(this);
-    mAudioPolicyManager = createAudioPolicyManager(mAudioPolicyClient);
+        mAudioPolicyClient = new AudioPolicyClient(this);
+        mAudioPolicyManager = createAudioPolicyManager(mAudioPolicyClient);
 #endif
-
+    }
     // load audio processing modules
-    mAudioPolicyEffects = new AudioPolicyEffects();
+    sp<AudioPolicyEffects>audioPolicyEffects = new AudioPolicyEffects();
+    {
+        Mutex::Autolock _l(mLock);
+        mAudioPolicyEffects = audioPolicyEffects;
+    }
 }
 
 AudioPolicyService::~AudioPolicyService()