Use audio_session_t consistently

Bug: 27562099
Change-Id: I328d8226191386b163f2ace41233607294c50dcd
diff --git a/services/audioflinger/AudioFlinger.cpp b/services/audioflinger/AudioFlinger.cpp
index 5980b58..d07ca85 100644
--- a/services/audioflinger/AudioFlinger.cpp
+++ b/services/audioflinger/AudioFlinger.cpp
@@ -552,7 +552,7 @@
         const sp<IMemory>& sharedBuffer,
         audio_io_handle_t output,
         pid_t tid,
-        int *sessionId,
+        audio_session_t *sessionId,
         int clientUid,
         status_t *status)
 {
@@ -560,7 +560,7 @@
     sp<TrackHandle> trackHandle;
     sp<Client> client;
     status_t lStatus;
-    int lSessionId;
+    audio_session_t lSessionId;
 
     // client AudioTrack::set already implements AUDIO_STREAM_DEFAULT => AUDIO_STREAM_MUSIC,
     // but if someone uses binder directly they could bypass that and cause us to crash
@@ -631,7 +631,7 @@
             }
         } else {
             // if no audio session id is provided, create one here
-            lSessionId = nextUniqueId(AUDIO_UNIQUE_ID_USE_SESSION);
+            lSessionId = (audio_session_t) nextUniqueId(AUDIO_UNIQUE_ID_USE_SESSION);
             if (sessionId != NULL) {
                 *sessionId = lSessionId;
             }
@@ -667,7 +667,7 @@
             }
         }
 
-        setAudioHwSyncForSession_l(thread, (audio_session_t)lSessionId);
+        setAudioHwSyncForSession_l(thread, lSessionId);
     }
 
     if (lStatus != NO_ERROR) {
@@ -1075,10 +1075,10 @@
                     audio_devices_t device = thread->inDevice();
                     bool suspend = audio_is_bluetooth_sco_device(device) && btNrecIsOff;
                     // collect all of the thread's session IDs
-                    KeyedVector<int, bool> ids = thread->sessionIds();
+                    KeyedVector<audio_session_t, bool> ids = thread->sessionIds();
                     // suspend effects associated with those session IDs
                     for (size_t j = 0; j < ids.size(); ++j) {
-                        int sessionId = ids.keyAt(j);
+                        audio_session_t sessionId = ids.keyAt(j);
                         thread->setEffectSuspended(FX_IID_AEC,
                                                    suspend,
                                                    sessionId);
@@ -1344,7 +1344,8 @@
 }
 
 // getEffectThread_l() must be called with AudioFlinger::mLock held
-sp<AudioFlinger::PlaybackThread> AudioFlinger::getEffectThread_l(int sessionId, int EffectId)
+sp<AudioFlinger::PlaybackThread> AudioFlinger::getEffectThread_l(audio_session_t sessionId,
+        int EffectId)
 {
     sp<PlaybackThread> thread;
 
@@ -1423,7 +1424,7 @@
         IAudioFlinger::track_flags_t *flags,
         pid_t tid,
         int clientUid,
-        int *sessionId,
+        audio_session_t *sessionId,
         size_t *notificationFrames,
         sp<IMemory>& cblk,
         sp<IMemory>& buffers,
@@ -1433,7 +1434,7 @@
     sp<RecordHandle> recordHandle;
     sp<Client> client;
     status_t lStatus;
-    int lSessionId;
+    audio_session_t lSessionId;
 
     cblk.clear();
     buffers.clear();
@@ -1493,7 +1494,7 @@
             lSessionId = *sessionId;
         } else {
             // if no audio session id is provided, create one here
-            lSessionId = nextUniqueId(AUDIO_UNIQUE_ID_USE_SESSION);
+            lSessionId = (audio_session_t) nextUniqueId(AUDIO_UNIQUE_ID_USE_SESSION);
             if (sessionId != NULL) {
                 *sessionId = lSessionId;
             }
@@ -1508,7 +1509,7 @@
         if (lStatus == NO_ERROR) {
             // Check if one effect chain was awaiting for an AudioRecord to be created on this
             // session and move it to this thread.
-            sp<EffectChain> chain = getOrphanEffectChain_l((audio_session_t)lSessionId);
+            sp<EffectChain> chain = getOrphanEffectChain_l(lSessionId);
             if (chain != 0) {
                 Mutex::Autolock _l(thread->mLock);
                 thread->addEffectChain_l(chain);
@@ -2270,7 +2271,7 @@
     return nextUniqueId(use);
 }
 
-void AudioFlinger::acquireAudioSessionId(int audioSession, pid_t pid)
+void AudioFlinger::acquireAudioSessionId(audio_session_t audioSession, pid_t pid)
 {
     Mutex::Autolock _l(mLock);
     pid_t caller = IPCThreadState::self()->getCallingPid();
@@ -2304,7 +2305,7 @@
     ALOGV(" added new entry for %d", audioSession);
 }
 
-void AudioFlinger::releaseAudioSessionId(int audioSession, pid_t pid)
+void AudioFlinger::releaseAudioSessionId(audio_session_t audioSession, pid_t pid)
 {
     Mutex::Autolock _l(mLock);
     pid_t caller = IPCThreadState::self()->getCallingPid();
@@ -2462,8 +2463,8 @@
 }
 
 sp<AudioFlinger::SyncEvent> AudioFlinger::createSyncEvent(AudioSystem::sync_event_t type,
-                                    int triggerSession,
-                                    int listenerSession,
+                                    audio_session_t triggerSession,
+                                    audio_session_t listenerSession,
                                     sync_event_callback_t callBack,
                                     wp<RefBase> cookie)
 {
@@ -2523,7 +2524,7 @@
         const sp<IEffectClient>& effectClient,
         int32_t priority,
         audio_io_handle_t io,
-        int sessionId,
+        audio_session_t sessionId,
         const String16& opPackageName,
         status_t *status,
         int *id,
@@ -2684,7 +2685,7 @@
         } else {
             // Check if one effect chain was awaiting for an effect to be created on this
             // session and used it instead of creating a new one.
-            sp<EffectChain> chain = getOrphanEffectChain_l((audio_session_t)sessionId);
+            sp<EffectChain> chain = getOrphanEffectChain_l(sessionId);
             if (chain != 0) {
                 Mutex::Autolock _l(thread->mLock);
                 thread->addEffectChain_l(chain);
@@ -2711,7 +2712,7 @@
     return handle;
 }
 
-status_t AudioFlinger::moveEffects(int sessionId, audio_io_handle_t srcOutput,
+status_t AudioFlinger::moveEffects(audio_session_t sessionId, audio_io_handle_t srcOutput,
         audio_io_handle_t dstOutput)
 {
     ALOGV("moveEffects() session %d, srcOutput %d, dstOutput %d",
@@ -2738,7 +2739,7 @@
 }
 
 // moveEffectChain_l must be called with both srcThread and dstThread mLocks held
-status_t AudioFlinger::moveEffectChain_l(int sessionId,
+status_t AudioFlinger::moveEffectChain_l(audio_session_t sessionId,
                                    AudioFlinger::PlaybackThread *srcThread,
                                    AudioFlinger::PlaybackThread *dstThread,
                                    bool reRegister)
@@ -2864,7 +2865,7 @@
 
 status_t AudioFlinger::putOrphanEffectChain_l(const sp<AudioFlinger::EffectChain>& chain)
 {
-    audio_session_t session = (audio_session_t)chain->sessionId();
+    audio_session_t session = chain->sessionId();
     ssize_t index = mOrphanEffectChains.indexOfKey(session);
     ALOGV("putOrphanEffectChain_l session %d index %d", session, index);
     if (index >= 0) {
@@ -2890,7 +2891,7 @@
 bool AudioFlinger::updateOrphanEffectChains(const sp<AudioFlinger::EffectModule>& effect)
 {
     Mutex::Autolock _l(mLock);
-    audio_session_t session = (audio_session_t)effect->sessionId();
+    audio_session_t session = effect->sessionId();
     ssize_t index = mOrphanEffectChains.indexOfKey(session);
     ALOGV("updateOrphanEffectChains session %d index %d", session, index);
     if (index >= 0) {
diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index fb1ece4..f11fd1c 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -108,7 +108,7 @@
                                 const sp<IMemory>& sharedBuffer,
                                 audio_io_handle_t output,
                                 pid_t tid,
-                                int *sessionId,
+                                audio_session_t *sessionId,
                                 int clientUid,
                                 status_t *status /*non-NULL*/);
 
@@ -122,7 +122,7 @@
                                 IAudioFlinger::track_flags_t *flags,
                                 pid_t tid,
                                 int clientUid,
-                                int *sessionId,
+                                audio_session_t *sessionId,
                                 size_t *notificationFrames,
                                 sp<IMemory>& cblk,
                                 sp<IMemory>& buffers,
@@ -198,9 +198,9 @@
 
     virtual audio_unique_id_t newAudioUniqueId(audio_unique_id_use_t use);
 
-    virtual void acquireAudioSessionId(int audioSession, pid_t pid);
+    virtual void acquireAudioSessionId(audio_session_t audioSession, pid_t pid);
 
-    virtual void releaseAudioSessionId(int audioSession, pid_t pid);
+    virtual void releaseAudioSessionId(audio_session_t audioSession, pid_t pid);
 
     virtual status_t queryNumberEffects(uint32_t *numEffects) const;
 
@@ -214,13 +214,13 @@
                         const sp<IEffectClient>& effectClient,
                         int32_t priority,
                         audio_io_handle_t io,
-                        int sessionId,
+                        audio_session_t sessionId,
                         const String16& opPackageName,
                         status_t *status /*non-NULL*/,
                         int *id,
                         int *enabled);
 
-    virtual status_t moveEffects(int sessionId, audio_io_handle_t srcOutput,
+    virtual status_t moveEffects(audio_session_t sessionId, audio_io_handle_t srcOutput,
                         audio_io_handle_t dstOutput);
 
     virtual audio_module_handle_t loadHwModule(const char *name);
@@ -283,8 +283,8 @@
     class SyncEvent : public RefBase {
     public:
         SyncEvent(AudioSystem::sync_event_t type,
-                  int triggerSession,
-                  int listenerSession,
+                  audio_session_t triggerSession,
+                  audio_session_t listenerSession,
                   sync_event_callback_t callBack,
                   wp<RefBase> cookie)
         : mType(type), mTriggerSession(triggerSession), mListenerSession(listenerSession),
@@ -297,22 +297,22 @@
         bool isCancelled() const { Mutex::Autolock _l(mLock); return (mCallback == NULL); }
         void cancel() { Mutex::Autolock _l(mLock); mCallback = NULL; }
         AudioSystem::sync_event_t type() const { return mType; }
-        int triggerSession() const { return mTriggerSession; }
-        int listenerSession() const { return mListenerSession; }
+        audio_session_t triggerSession() const { return mTriggerSession; }
+        audio_session_t listenerSession() const { return mListenerSession; }
         wp<RefBase> cookie() const { return mCookie; }
 
     private:
           const AudioSystem::sync_event_t mType;
-          const int mTriggerSession;
-          const int mListenerSession;
+          const audio_session_t mTriggerSession;
+          const audio_session_t mListenerSession;
           sync_event_callback_t mCallback;
           const wp<RefBase> mCookie;
           mutable Mutex mLock;
     };
 
     sp<SyncEvent> createSyncEvent(AudioSystem::sync_event_t type,
-                                        int triggerSession,
-                                        int listenerSession,
+                                        audio_session_t triggerSession,
+                                        audio_session_t listenerSession,
                                         sync_event_callback_t callBack,
                                         wp<RefBase> cookie);
 
@@ -505,7 +505,8 @@
     public:
         RecordHandle(const sp<RecordThread::RecordTrack>& recordTrack);
         virtual             ~RecordHandle();
-        virtual status_t    start(int /*AudioSystem::sync_event_t*/ event, int triggerSession);
+        virtual status_t    start(int /*AudioSystem::sync_event_t*/ event,
+                audio_session_t triggerSession);
         virtual void        stop();
         virtual status_t onTransact(
             uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags);
@@ -560,7 +561,7 @@
               //       or by returning a non-unique ID.
               audio_unique_id_t nextUniqueId(audio_unique_id_use_t use);
 
-              status_t moveEffectChain_l(int sessionId,
+              status_t moveEffectChain_l(audio_session_t sessionId,
                                      PlaybackThread *srcThread,
                                      PlaybackThread *dstThread,
                                      bool reRegister);
@@ -569,7 +570,7 @@
               PlaybackThread *primaryPlaybackThread_l() const;
               audio_devices_t primaryOutputDevice_l() const;
 
-              sp<PlaybackThread> getEffectThread_l(int sessionId, int EffectId);
+              sp<PlaybackThread> getEffectThread_l(audio_session_t sessionId, int EffectId);
 
 
                 void        removeClient_l(pid_t pid);
@@ -612,9 +613,9 @@
 
     // for mAudioSessionRefs only
     struct AudioSessionRef {
-        AudioSessionRef(int sessionid, pid_t pid) :
+        AudioSessionRef(audio_session_t sessionid, pid_t pid) :
             mSessionid(sessionid), mPid(pid), mCnt(1) {}
-        const int   mSessionid;
+        const audio_session_t mSessionid;
         const pid_t mPid;
         int         mCnt;
     };
diff --git a/services/audioflinger/Effects.cpp b/services/audioflinger/Effects.cpp
index 949c91d..060ffe9 100644
--- a/services/audioflinger/Effects.cpp
+++ b/services/audioflinger/Effects.cpp
@@ -59,7 +59,7 @@
                                         const wp<AudioFlinger::EffectChain>& chain,
                                         effect_descriptor_t *desc,
                                         int id,
-                                        int sessionId)
+                                        audio_session_t sessionId)
     : mPinned(sessionId > AUDIO_SESSION_OUTPUT_MIX),
       mThread(thread), mChain(chain), mId(id), mSessionId(sessionId),
       mDescriptor(*desc),
@@ -1341,7 +1341,7 @@
 #define LOG_TAG "AudioFlinger::EffectChain"
 
 AudioFlinger::EffectChain::EffectChain(ThreadBase *thread,
-                                        int sessionId)
+                                        audio_session_t sessionId)
     : mThread(thread), mSessionId(sessionId), mActiveTrackCnt(0), mTrackCnt(0), mTailBufferCount(0),
       mOwnInBuffer(false), mVolumeCtrlIdx(-1), mLeftVolume(UINT_MAX), mRightVolume(UINT_MAX),
       mNewLeftVolume(UINT_MAX), mNewRightVolume(UINT_MAX), mForceVolume(false)
diff --git a/services/audioflinger/Effects.h b/services/audioflinger/Effects.h
index 6f93f81..bc9bc94 100644
--- a/services/audioflinger/Effects.h
+++ b/services/audioflinger/Effects.h
@@ -45,7 +45,7 @@
                     const wp<AudioFlinger::EffectChain>& chain,
                     effect_descriptor_t *desc,
                     int id,
-                    int sessionId);
+                    audio_session_t sessionId);
     virtual ~EffectModule();
 
     enum effect_state {
@@ -76,7 +76,7 @@
     uint32_t status() {
         return mStatus;
     }
-    int sessionId() const {
+    audio_session_t sessionId() const {
         return mSessionId;
     }
     status_t    setEnabled(bool enabled);
@@ -141,7 +141,7 @@
     wp<ThreadBase>      mThread;    // parent thread
     wp<EffectChain>     mChain;     // parent effect chain
     const int           mId;        // this instance unique ID
-    const int           mSessionId; // audio session ID
+    const audio_session_t mSessionId; // audio session ID
     const effect_descriptor_t mDescriptor;// effect descriptor received from effect engine
     effect_config_t     mConfig;    // input and output audio configuration
     effect_handle_t  mEffectInterface; // Effect module C API
@@ -235,15 +235,17 @@
 
 // the EffectChain class represents a group of effects associated to one audio session.
 // There can be any number of EffectChain objects per output mixer thread (PlaybackThread).
-// The EffecChain with session ID 0 contains global effects applied to the output mix.
+// The EffectChain with session ID AUDIO_SESSION_OUTPUT_MIX contains global effects applied
+// to the output mix.
 // Effects in this chain can be insert or auxiliary. Effects in other chains (attached to
 // tracks) are insert only. The EffectChain maintains an ordered list of effect module, the
-// order corresponding in the effect process order. When attached to a track (session ID != 0),
+// order corresponding in the effect process order. When attached to a track (session ID !=
+// AUDIO_SESSION_OUTPUT_MIX),
 // it also provide it's own input buffer used by the track as accumulation buffer.
 class EffectChain : public RefBase {
 public:
-    EffectChain(const wp<ThreadBase>& wThread, int sessionId);
-    EffectChain(ThreadBase *thread, int sessionId);
+    EffectChain(const wp<ThreadBase>& wThread, audio_session_t sessionId);
+    EffectChain(ThreadBase *thread, audio_session_t sessionId);
     virtual ~EffectChain();
 
     // special key used for an entry in mSuspendedEffects keyed vector
@@ -266,8 +268,8 @@
     status_t addEffect_l(const sp<EffectModule>& handle);
     size_t removeEffect_l(const sp<EffectModule>& handle);
 
-    int sessionId() const { return mSessionId; }
-    void setSessionId(int sessionId) { mSessionId = sessionId; }
+    audio_session_t sessionId() const { return mSessionId; }
+    void setSessionId(audio_session_t sessionId) { mSessionId = sessionId; }
 
     sp<EffectModule> getEffectFromDesc_l(effect_descriptor_t *descriptor);
     sp<EffectModule> getEffectFromId_l(int id);
@@ -362,7 +364,7 @@
     wp<ThreadBase> mThread;     // parent mixer thread
     Mutex mLock;                // mutex protecting effect list
     Vector< sp<EffectModule> > mEffects; // list of effect modules
-    int mSessionId;             // audio session ID
+    audio_session_t mSessionId; // audio session ID
     int16_t *mInBuffer;         // chain input buffer
     int16_t *mOutBuffer;        // chain output buffer
 
diff --git a/services/audioflinger/PatchPanel.cpp b/services/audioflinger/PatchPanel.cpp
index 27149ed..a99becf 100644
--- a/services/audioflinger/PatchPanel.cpp
+++ b/services/audioflinger/PatchPanel.cpp
@@ -453,7 +453,7 @@
     patch->mPatchTrack->setPeerProxy(patch->mPatchRecord.get());
 
     // start capture and playback
-    patch->mPatchRecord->start(AudioSystem::SYNC_EVENT_NONE, 0);
+    patch->mPatchRecord->start(AudioSystem::SYNC_EVENT_NONE, AUDIO_SESSION_NONE);
     patch->mPatchTrack->start();
 
     return status;
diff --git a/services/audioflinger/PlaybackTracks.h b/services/audioflinger/PlaybackTracks.h
index 6e0c46d..270e27f 100644
--- a/services/audioflinger/PlaybackTracks.h
+++ b/services/audioflinger/PlaybackTracks.h
@@ -31,7 +31,7 @@
                                 size_t frameCount,
                                 void *buffer,
                                 const sp<IMemory>& sharedBuffer,
-                                int sessionId,
+                                audio_session_t sessionId,
                                 int uid,
                                 IAudioFlinger::track_flags_t flags,
                                 track_type type);
@@ -42,7 +42,7 @@
             void        dump(char* buffer, size_t size, bool active);
     virtual status_t    start(AudioSystem::sync_event_t event =
                                     AudioSystem::SYNC_EVENT_NONE,
-                             int triggerSession = 0);
+                             audio_session_t triggerSession = AUDIO_SESSION_NONE);
     virtual void        stop();
             void        pause();
 
@@ -190,7 +190,7 @@
 
     virtual status_t    start(AudioSystem::sync_event_t event =
                                     AudioSystem::SYNC_EVENT_NONE,
-                             int triggerSession = 0);
+                             audio_session_t triggerSession = AUDIO_SESSION_NONE);
     virtual void        stop();
             bool        write(void* data, uint32_t frames);
             bool        bufferQueueEmpty() const { return mBufferQueue.size() == 0; }
@@ -231,7 +231,7 @@
 
     virtual status_t    start(AudioSystem::sync_event_t event =
                                     AudioSystem::SYNC_EVENT_NONE,
-                             int triggerSession = 0);
+                             audio_session_t triggerSession = AUDIO_SESSION_NONE);
 
     // AudioBufferProvider interface
     virtual status_t getNextBuffer(AudioBufferProvider::Buffer* buffer);
diff --git a/services/audioflinger/RecordTracks.h b/services/audioflinger/RecordTracks.h
index 6f84af1..13396a6 100644
--- a/services/audioflinger/RecordTracks.h
+++ b/services/audioflinger/RecordTracks.h
@@ -29,14 +29,14 @@
                                 audio_channel_mask_t channelMask,
                                 size_t frameCount,
                                 void *buffer,
-                                int sessionId,
+                                audio_session_t sessionId,
                                 int uid,
                                 IAudioFlinger::track_flags_t flags,
                                 track_type type);
     virtual             ~RecordTrack();
     virtual status_t    initCheck() const;
 
-    virtual status_t    start(AudioSystem::sync_event_t event, int triggerSession);
+    virtual status_t    start(AudioSystem::sync_event_t event, audio_session_t triggerSession);
     virtual void        stop();
 
             void        destroy();
diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index f206e96..e2932f1 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -1134,14 +1134,14 @@
 }
 
 void AudioFlinger::ThreadBase::setEffectSuspended(
-        const effect_uuid_t *type, bool suspend, int sessionId)
+        const effect_uuid_t *type, bool suspend, audio_session_t sessionId)
 {
     Mutex::Autolock _l(mLock);
     setEffectSuspended_l(type, suspend, sessionId);
 }
 
 void AudioFlinger::ThreadBase::setEffectSuspended_l(
-        const effect_uuid_t *type, bool suspend, int sessionId)
+        const effect_uuid_t *type, bool suspend, audio_session_t sessionId)
 {
     sp<EffectChain> chain = getEffectChain_l(sessionId);
     if (chain != 0) {
@@ -1181,7 +1181,7 @@
 
 void AudioFlinger::ThreadBase::updateSuspendedSessions_l(const effect_uuid_t *type,
                                                          bool suspend,
-                                                         int sessionId)
+                                                         audio_session_t sessionId)
 {
     ssize_t index = mSuspendedSessions.indexOfKey(sessionId);
 
@@ -1242,7 +1242,7 @@
 
 void AudioFlinger::ThreadBase::checkSuspendOnEffectEnabled(const sp<EffectModule>& effect,
                                                             bool enabled,
-                                                            int sessionId)
+                                                            audio_session_t sessionId)
 {
     Mutex::Autolock _l(mLock);
     checkSuspendOnEffectEnabled_l(effect, enabled, sessionId);
@@ -1250,7 +1250,7 @@
 
 void AudioFlinger::ThreadBase::checkSuspendOnEffectEnabled_l(const sp<EffectModule>& effect,
                                                             bool enabled,
-                                                            int sessionId)
+                                                            audio_session_t sessionId)
 {
     if (mType != RECORD) {
         // suspend all effects in AUDIO_SESSION_OUTPUT_MIX when enabling any effect on
@@ -1274,7 +1274,7 @@
         const sp<AudioFlinger::Client>& client,
         const sp<IEffectClient>& effectClient,
         int32_t priority,
-        int sessionId,
+        audio_session_t sessionId,
         effect_descriptor_t *desc,
         int *enabled,
         status_t *status)
@@ -1413,13 +1413,15 @@
     return handle;
 }
 
-sp<AudioFlinger::EffectModule> AudioFlinger::ThreadBase::getEffect(int sessionId, int effectId)
+sp<AudioFlinger::EffectModule> AudioFlinger::ThreadBase::getEffect(audio_session_t sessionId,
+        int effectId)
 {
     Mutex::Autolock _l(mLock);
     return getEffect_l(sessionId, effectId);
 }
 
-sp<AudioFlinger::EffectModule> AudioFlinger::ThreadBase::getEffect_l(int sessionId, int effectId)
+sp<AudioFlinger::EffectModule> AudioFlinger::ThreadBase::getEffect_l(audio_session_t sessionId,
+        int effectId)
 {
     sp<EffectChain> chain = getEffectChain_l(sessionId);
     return chain != 0 ? chain->getEffectFromId_l(effectId) : 0;
@@ -1430,7 +1432,7 @@
 status_t AudioFlinger::ThreadBase::addEffect_l(const sp<EffectModule>& effect)
 {
     // check for existing effect chain with the requested audio session
-    int sessionId = effect->sessionId();
+    audio_session_t sessionId = effect->sessionId();
     sp<EffectChain> chain = getEffectChain_l(sessionId);
     bool chainCreated = false;
 
@@ -1507,13 +1509,14 @@
     }
 }
 
-sp<AudioFlinger::EffectChain> AudioFlinger::ThreadBase::getEffectChain(int sessionId)
+sp<AudioFlinger::EffectChain> AudioFlinger::ThreadBase::getEffectChain(audio_session_t sessionId)
 {
     Mutex::Autolock _l(mLock);
     return getEffectChain_l(sessionId);
 }
 
-sp<AudioFlinger::EffectChain> AudioFlinger::ThreadBase::getEffectChain_l(int sessionId) const
+sp<AudioFlinger::EffectChain> AudioFlinger::ThreadBase::getEffectChain_l(audio_session_t sessionId)
+        const
 {
     size_t size = mEffectChains.size();
     for (size_t i = 0; i < size; i++) {
@@ -1769,7 +1772,7 @@
         audio_channel_mask_t channelMask,
         size_t *pFrameCount,
         const sp<IMemory>& sharedBuffer,
-        int sessionId,
+        audio_session_t sessionId,
         IAudioFlinger::track_flags_t *flags,
         pid_t tid,
         int uid,
@@ -2039,14 +2042,14 @@
             TrackBase::track_state state = track->mState;
             mLock.unlock();
             status = AudioSystem::startOutput(mId, track->streamType(),
-                                              (audio_session_t)track->sessionId());
+                                              track->sessionId());
             mLock.lock();
             // abort track was stopped/paused while we released the lock
             if (state != track->mState) {
                 if (status == NO_ERROR) {
                     mLock.unlock();
                     AudioSystem::stopOutput(mId, track->streamType(),
-                                            (audio_session_t)track->sessionId());
+                                            track->sessionId());
                     mLock.lock();
                 }
                 return INVALID_OPERATION;
@@ -2421,7 +2424,7 @@
     }
 }
 
-uint32_t AudioFlinger::PlaybackThread::hasAudioSession(int sessionId) const
+uint32_t AudioFlinger::PlaybackThread::hasAudioSession(audio_session_t sessionId) const
 {
     Mutex::Autolock _l(mLock);
     uint32_t result = 0;
@@ -2440,7 +2443,7 @@
     return result;
 }
 
-uint32_t AudioFlinger::PlaybackThread::getStrategyForSession_l(int sessionId)
+uint32_t AudioFlinger::PlaybackThread::getStrategyForSession_l(audio_session_t sessionId)
 {
     // session AUDIO_SESSION_OUTPUT_MIX is placed in same strategy as MUSIC stream so that
     // it is moved to correct output by audio policy manager when A2DP is connected or disconnected
@@ -2523,14 +2526,14 @@
             const sp<Track>& track = tracksToRemove.itemAt(i);
             if (track->isExternalTrack()) {
                 AudioSystem::stopOutput(mId, track->streamType(),
-                                        (audio_session_t)track->sessionId());
+                                        track->sessionId());
 #ifdef ADD_BATTERY_DATA
                 // to track the speaker usage
                 addBatteryData(IMediaPlayerService::kBatteryDataAudioFlingerStop);
 #endif
                 if (track->isTerminated()) {
                     AudioSystem::releaseOutput(mId, track->streamType(),
-                                               (audio_session_t)track->sessionId());
+                                               track->sessionId());
                 }
             }
         }
@@ -2696,13 +2699,13 @@
 
 status_t AudioFlinger::PlaybackThread::addEffectChain_l(const sp<EffectChain>& chain)
 {
-    int session = chain->sessionId();
+    audio_session_t session = chain->sessionId();
     int16_t* buffer = reinterpret_cast<int16_t*>(mEffectBufferEnabled
             ? mEffectBuffer : mSinkBuffer);
     bool ownsBuffer = false;
 
     ALOGV("addEffectChain_l() %p on thread %p for session %d", chain.get(), this, session);
-    if (session > 0) {
+    if (session > AUDIO_SESSION_OUTPUT_MIX) {
         // Only one effect chain can be present in direct output thread and it uses
         // the sink buffer as input
         if (mType != DIRECT) {
@@ -2741,15 +2744,18 @@
     chain->setOutBuffer(reinterpret_cast<int16_t*>(mEffectBufferEnabled
             ? mEffectBuffer : mSinkBuffer));
     // Effect chain for session AUDIO_SESSION_OUTPUT_STAGE is inserted at end of effect
-    // chains list in order to be processed last as it contains output stage effects
+    // chains list in order to be processed last as it contains output stage effects.
     // Effect chain for session AUDIO_SESSION_OUTPUT_MIX is inserted before
     // session AUDIO_SESSION_OUTPUT_STAGE to be processed
-    // after track specific effects and before output stage
+    // after track specific effects and before output stage.
     // It is therefore mandatory that AUDIO_SESSION_OUTPUT_MIX == 0 and
-    // that AUDIO_SESSION_OUTPUT_STAGE < AUDIO_SESSION_OUTPUT_MIX
+    // that AUDIO_SESSION_OUTPUT_STAGE < AUDIO_SESSION_OUTPUT_MIX.
     // Effect chain for other sessions are inserted at beginning of effect
     // chains list to be processed before output mix effects. Relative order between other
-    // sessions is not important
+    // sessions is not important.
+    static_assert(AUDIO_SESSION_OUTPUT_MIX == 0 &&
+            AUDIO_SESSION_OUTPUT_STAGE < AUDIO_SESSION_OUTPUT_MIX,
+            "audio_session_t constants misdefined");
     size_t size = mEffectChains.size();
     size_t i = 0;
     for (i = 0; i < size; i++) {
@@ -2765,7 +2771,7 @@
 
 size_t AudioFlinger::PlaybackThread::removeEffectChain_l(const sp<EffectChain>& chain)
 {
-    int session = chain->sessionId();
+    audio_session_t session = chain->sessionId();
 
     ALOGV("removeEffectChain_l() %p from thread %p for session %d", chain.get(), this, session);
 
@@ -4427,7 +4433,7 @@
 
 // getTrackName_l() must be called with ThreadBase::mLock held
 int AudioFlinger::MixerThread::getTrackName_l(audio_channel_mask_t channelMask,
-        audio_format_t format, int sessionId)
+        audio_format_t format, audio_session_t sessionId)
 {
     return mAudioMixer->getTrackName(channelMask, format, sessionId);
 }
@@ -5003,7 +5009,7 @@
 
 // getTrackName_l() must be called with ThreadBase::mLock held
 int AudioFlinger::DirectOutputThread::getTrackName_l(audio_channel_mask_t channelMask __unused,
-        audio_format_t format __unused, int sessionId __unused)
+        audio_format_t format __unused, audio_session_t sessionId __unused)
 {
     return 0;
 }
@@ -6201,7 +6207,8 @@
                                   (activeTrack->mFramesToDrop >= 0) ? "timed out" : "cancelled",
                                   activeTrack->sessionId(),
                                   (activeTrack->mSyncStartEvent != 0) ?
-                                          activeTrack->mSyncStartEvent->triggerSession() : 0);
+                                          activeTrack->mSyncStartEvent->triggerSession() :
+                                          AUDIO_SESSION_NONE);
                             activeTrack->clearSyncStartEvent();
                         }
                     }
@@ -6307,7 +6314,7 @@
         audio_format_t format,
         audio_channel_mask_t channelMask,
         size_t *pFrameCount,
-        int sessionId,
+        audio_session_t sessionId,
         size_t *notificationFrames,
         int uid,
         IAudioFlinger::track_flags_t *flags,
@@ -6426,7 +6433,7 @@
 
 status_t AudioFlinger::RecordThread::start(RecordThread::RecordTrack* recordTrack,
                                            AudioSystem::sync_event_t event,
-                                           int triggerSession)
+                                           audio_session_t triggerSession)
 {
     ALOGV("RecordThread::start event %d, triggerSession %d", event, triggerSession);
     sp<ThreadBase> strongMe = this;
@@ -6473,7 +6480,7 @@
         status_t status = NO_ERROR;
         if (recordTrack->isExternalTrack()) {
             mLock.unlock();
-            status = AudioSystem::startInput(mId, (audio_session_t)recordTrack->sessionId());
+            status = AudioSystem::startInput(mId, recordTrack->sessionId());
             mLock.lock();
             // FIXME should verify that recordTrack is still in mActiveTracks
             if (status != NO_ERROR) {
@@ -6505,7 +6512,7 @@
 
 startError:
     if (recordTrack->isExternalTrack()) {
-        AudioSystem::stopInput(mId, (audio_session_t)recordTrack->sessionId());
+        AudioSystem::stopInput(mId, recordTrack->sessionId());
     }
     recordTrack->clearSyncStartEvent();
     // FIXME I wonder why we do not reset the state here?
@@ -6559,7 +6566,7 @@
         return BAD_VALUE;
     }
 
-    int eventSession = event->triggerSession();
+    audio_session_t eventSession = event->triggerSession();
     status_t ret = NAME_NOT_FOUND;
 
     Mutex::Autolock _l(mLock);
@@ -7225,7 +7232,7 @@
     return mInput->stream->get_input_frames_lost(mInput->stream);
 }
 
-uint32_t AudioFlinger::RecordThread::hasAudioSession(int sessionId) const
+uint32_t AudioFlinger::RecordThread::hasAudioSession(audio_session_t sessionId) const
 {
     Mutex::Autolock _l(mLock);
     uint32_t result = 0;
@@ -7243,13 +7250,13 @@
     return result;
 }
 
-KeyedVector<int, bool> AudioFlinger::RecordThread::sessionIds() const
+KeyedVector<audio_session_t, bool> AudioFlinger::RecordThread::sessionIds() const
 {
-    KeyedVector<int, bool> ids;
+    KeyedVector<audio_session_t, bool> ids;
     Mutex::Autolock _l(mLock);
     for (size_t j = 0; j < mTracks.size(); ++j) {
         sp<RecordThread::RecordTrack> track = mTracks[j];
-        int sessionId = track->sessionId();
+        audio_session_t sessionId = track->sessionId();
         if (ids.indexOfKey(sessionId) < 0) {
             ids.add(sessionId, true);
         }
diff --git a/services/audioflinger/Threads.h b/services/audioflinger/Threads.h
index d1613db..761fc71 100644
--- a/services/audioflinger/Threads.h
+++ b/services/audioflinger/Threads.h
@@ -288,7 +288,7 @@
                                     const sp<AudioFlinger::Client>& client,
                                     const sp<IEffectClient>& effectClient,
                                     int32_t priority,
-                                    int sessionId,
+                                    audio_session_t sessionId,
                                     effect_descriptor_t *desc,
                                     int *enabled,
                                     status_t *status /*non-NULL*/);
@@ -302,9 +302,9 @@
                 };
 
                 // get effect chain corresponding to session Id.
-                sp<EffectChain> getEffectChain(int sessionId);
+                sp<EffectChain> getEffectChain(audio_session_t sessionId);
                 // same as getEffectChain() but must be called with ThreadBase mutex locked
-                sp<EffectChain> getEffectChain_l(int sessionId) const;
+                sp<EffectChain> getEffectChain_l(audio_session_t sessionId) const;
                 // add an effect chain to the chain list (mEffectChains)
     virtual     status_t addEffectChain_l(const sp<EffectChain>& chain) = 0;
                 // remove an effect chain from the chain list (mEffectChains)
@@ -321,8 +321,8 @@
                 // set audio mode to all effect chains
                 void setMode(audio_mode_t mode);
                 // get effect module with corresponding ID on specified audio session
-                sp<AudioFlinger::EffectModule> getEffect(int sessionId, int effectId);
-                sp<AudioFlinger::EffectModule> getEffect_l(int sessionId, int effectId);
+                sp<AudioFlinger::EffectModule> getEffect(audio_session_t sessionId, int effectId);
+                sp<AudioFlinger::EffectModule> getEffect_l(audio_session_t sessionId, int effectId);
                 // add and effect module. Also creates the effect chain is none exists for
                 // the effects audio session
                 status_t addEffect_l(const sp< EffectModule>& effect);
@@ -333,24 +333,27 @@
     virtual     void detachAuxEffect_l(int effectId __unused) {}
                 // returns either EFFECT_SESSION if effects on this audio session exist in one
                 // chain, or TRACK_SESSION if tracks on this audio session exist, or both
-                virtual uint32_t hasAudioSession(int sessionId) const = 0;
+                virtual uint32_t hasAudioSession(audio_session_t sessionId) const = 0;
                 // the value returned by default implementation is not important as the
                 // strategy is only meaningful for PlaybackThread which implements this method
-                virtual uint32_t getStrategyForSession_l(int sessionId __unused) { return 0; }
+                virtual uint32_t getStrategyForSession_l(audio_session_t sessionId __unused)
+                        { return 0; }
 
                 // suspend or restore effect according to the type of effect passed. a NULL
                 // type pointer means suspend all effects in the session
                 void setEffectSuspended(const effect_uuid_t *type,
                                         bool suspend,
-                                        int sessionId = AUDIO_SESSION_OUTPUT_MIX);
+                                        audio_session_t sessionId = AUDIO_SESSION_OUTPUT_MIX);
                 // check if some effects must be suspended/restored when an effect is enabled
                 // or disabled
                 void checkSuspendOnEffectEnabled(const sp<EffectModule>& effect,
                                                  bool enabled,
-                                                 int sessionId = AUDIO_SESSION_OUTPUT_MIX);
+                                                 audio_session_t sessionId =
+                                                        AUDIO_SESSION_OUTPUT_MIX);
                 void checkSuspendOnEffectEnabled_l(const sp<EffectModule>& effect,
                                                    bool enabled,
-                                                   int sessionId = AUDIO_SESSION_OUTPUT_MIX);
+                                                   audio_session_t sessionId =
+                                                        AUDIO_SESSION_OUTPUT_MIX);
 
                 virtual status_t    setSyncEvent(const sp<SyncEvent>& event) = 0;
                 virtual bool        isValidSyncEvent(const sp<SyncEvent>& event) const = 0;
@@ -389,11 +392,11 @@
                 void        getPowerManager_l();
                 void setEffectSuspended_l(const effect_uuid_t *type,
                                           bool suspend,
-                                          int sessionId);
+                                          audio_session_t sessionId);
                 // updated mSuspendedSessions when an effect suspended or restored
                 void        updateSuspendedSessions_l(const effect_uuid_t *type,
                                                       bool suspend,
-                                                      int sessionId);
+                                                      audio_session_t sessionId);
                 // check if some effects must be suspended when an effect chain is added
                 void checkSuspendOnAddEffectChain_l(const sp<EffectChain>& chain);
 
@@ -452,9 +455,9 @@
                 sp<IPowerManager>       mPowerManager;
                 sp<IBinder>             mWakeLockToken;
                 const sp<PMDeathRecipient> mDeathRecipient;
-                // list of suspended effects per session and per type. The first vector is
-                // keyed by session ID, the second by type UUID timeLow field
-                KeyedVector< int, KeyedVector< int, sp<SuspendedSessionDesc> > >
+                // list of suspended effects per session and per type. The first (outer) vector is
+                // keyed by session ID, the second (inner) by type UUID timeLow field
+                KeyedVector< audio_session_t, KeyedVector< int, sp<SuspendedSessionDesc> > >
                                         mSuspendedSessions;
                 static const size_t     kLogSize = 4 * 1024;
                 sp<NBLog::Writer>       mNBLogWriter;
@@ -549,7 +552,7 @@
                                 audio_channel_mask_t channelMask,
                                 size_t *pFrameCount,
                                 const sp<IMemory>& sharedBuffer,
-                                int sessionId,
+                                audio_session_t sessionId,
                                 IAudioFlinger::track_flags_t *flags,
                                 pid_t tid,
                                 int uid,
@@ -589,8 +592,8 @@
 
                 virtual status_t addEffectChain_l(const sp<EffectChain>& chain);
                 virtual size_t removeEffectChain_l(const sp<EffectChain>& chain);
-                virtual uint32_t hasAudioSession(int sessionId) const;
-                virtual uint32_t getStrategyForSession_l(int sessionId);
+                virtual uint32_t hasAudioSession(audio_session_t sessionId) const;
+                virtual uint32_t getStrategyForSession_l(audio_session_t sessionId);
 
 
                 virtual status_t setSyncEvent(const sp<SyncEvent>& event);
@@ -704,7 +707,7 @@
     // Allocate a track name for a given channel mask.
     //   Returns name >= 0 if successful, -1 on failure.
     virtual int             getTrackName_l(audio_channel_mask_t channelMask,
-                                           audio_format_t format, int sessionId) = 0;
+                                           audio_format_t format, audio_session_t sessionId) = 0;
     virtual void            deleteTrackName_l(int name) = 0;
 
     // Time to sleep between cycles when:
@@ -859,7 +862,7 @@
 protected:
     virtual     mixer_state prepareTracks_l(Vector< sp<Track> > *tracksToRemove);
     virtual     int         getTrackName_l(audio_channel_mask_t channelMask,
-                                           audio_format_t format, int sessionId);
+                                           audio_format_t format, audio_session_t sessionId);
     virtual     void        deleteTrackName_l(int name);
     virtual     uint32_t    idleSleepTimeUs() const;
     virtual     uint32_t    suspendSleepTimeUs() const;
@@ -940,7 +943,7 @@
 
 protected:
     virtual     int         getTrackName_l(audio_channel_mask_t channelMask,
-                                           audio_format_t format, int sessionId);
+                                           audio_format_t format, audio_session_t sessionId);
     virtual     void        deleteTrackName_l(int name);
     virtual     uint32_t    activeSleepTimeUs() const;
     virtual     uint32_t    idleSleepTimeUs() const;
@@ -1243,7 +1246,7 @@
                     audio_format_t format,
                     audio_channel_mask_t channelMask,
                     size_t *pFrameCount,
-                    int sessionId,
+                    audio_session_t sessionId,
                     size_t *notificationFrames,
                     int uid,
                     IAudioFlinger::track_flags_t *flags,
@@ -1252,7 +1255,7 @@
 
             status_t    start(RecordTrack* recordTrack,
                               AudioSystem::sync_event_t event,
-                              int triggerSession);
+                              audio_session_t triggerSession);
 
             // ask the thread to stop the specified track, and
             // return true if the caller should then do it's part of the stopping process
@@ -1280,12 +1283,12 @@
 
     virtual status_t addEffectChain_l(const sp<EffectChain>& chain);
     virtual size_t removeEffectChain_l(const sp<EffectChain>& chain);
-    virtual uint32_t hasAudioSession(int sessionId) const;
+    virtual uint32_t hasAudioSession(audio_session_t sessionId) const;
 
             // Return the set of unique session IDs across all tracks.
             // The keys are the session IDs, and the associated values are meaningless.
             // FIXME replace by Set [and implement Bag/Multiset for other uses].
-            KeyedVector<int, bool> sessionIds() const;
+            KeyedVector<audio_session_t, bool> sessionIds() const;
 
     virtual status_t setSyncEvent(const sp<SyncEvent>& event);
     virtual bool     isValidSyncEvent(const sp<SyncEvent>& event) const;
diff --git a/services/audioflinger/TrackBase.h b/services/audioflinger/TrackBase.h
index 26067e3..67a5e58 100644
--- a/services/audioflinger/TrackBase.h
+++ b/services/audioflinger/TrackBase.h
@@ -61,7 +61,7 @@
                                 audio_channel_mask_t channelMask,
                                 size_t frameCount,
                                 void *buffer,
-                                int sessionId,
+                                audio_session_t sessionId,
                                 int uid,
                                 IAudioFlinger::track_flags_t flags,
                                 bool isOut,
@@ -71,11 +71,11 @@
     virtual status_t    initCheck() const;
 
     virtual status_t    start(AudioSystem::sync_event_t event,
-                             int triggerSession) = 0;
+                             audio_session_t triggerSession) = 0;
     virtual void        stop() = 0;
             sp<IMemory> getCblk() const { return mCblkMemory; }
             audio_track_cblk_t* cblk() const { return mCblk; }
-            int         sessionId() const { return mSessionId; }
+            audio_session_t sessionId() const { return mSessionId; }
             int         uid() const { return mUid; }
     virtual status_t    setSyncEvent(const sp<SyncEvent>& event);
 
@@ -153,7 +153,7 @@
     const size_t        mFrameCount;// size of track buffer given at createTrack() or
                                     // openRecord(), and then adjusted as needed
 
-    const int           mSessionId;
+    const audio_session_t mSessionId;
     int                 mUid;
     Vector < sp<SyncEvent> >mSyncEvents;
     const IAudioFlinger::track_flags_t mFlags;
diff --git a/services/audioflinger/Tracks.cpp b/services/audioflinger/Tracks.cpp
index 0c51e81..0e557eb 100644
--- a/services/audioflinger/Tracks.cpp
+++ b/services/audioflinger/Tracks.cpp
@@ -71,7 +71,7 @@
             audio_channel_mask_t channelMask,
             size_t frameCount,
             void *buffer,
-            int sessionId,
+            audio_session_t sessionId,
             int clientUid,
             IAudioFlinger::track_flags_t flags,
             bool isOut,
@@ -343,7 +343,7 @@
             size_t frameCount,
             void *buffer,
             const sp<IMemory>& sharedBuffer,
-            int sessionId,
+            audio_session_t sessionId,
             int uid,
             IAudioFlinger::track_flags_t flags,
             track_type type)
@@ -454,7 +454,7 @@
             wasActive = playbackThread->destroyTrack_l(this);
         }
         if (isExternalTrack() && !wasActive) {
-            AudioSystem::releaseOutput(mThreadIoHandle, mStreamType, (audio_session_t)mSessionId);
+            AudioSystem::releaseOutput(mThreadIoHandle, mStreamType, mSessionId);
         }
     }
 }
@@ -627,7 +627,7 @@
 }
 
 status_t AudioFlinger::PlaybackThread::Track::start(AudioSystem::sync_event_t event __unused,
-                                                    int triggerSession __unused)
+                                                    audio_session_t triggerSession __unused)
 {
     status_t status = NO_ERROR;
     ALOGV("start(%d), calling pid %d session %d",
@@ -1128,7 +1128,8 @@
             int uid)
     :   Track(playbackThread, NULL, AUDIO_STREAM_PATCH,
               sampleRate, format, channelMask, frameCount,
-              NULL, 0, 0, uid, IAudioFlinger::TRACK_DEFAULT, TYPE_OUTPUT),
+              NULL, 0, AUDIO_SESSION_NONE, uid, IAudioFlinger::TRACK_DEFAULT,
+              TYPE_OUTPUT),
     mActive(false), mSourceThread(sourceThread), mClientProxy(NULL)
 {
 
@@ -1159,7 +1160,7 @@
 }
 
 status_t AudioFlinger::PlaybackThread::OutputTrack::start(AudioSystem::sync_event_t event,
-                                                          int triggerSession)
+                                                          audio_session_t triggerSession)
 {
     status_t status = Track::start(event, triggerSession);
     if (status != NO_ERROR) {
@@ -1326,7 +1327,7 @@
                                                      IAudioFlinger::track_flags_t flags)
     :   Track(playbackThread, NULL, streamType,
               sampleRate, format, channelMask, frameCount,
-              buffer, 0, 0, getuid(), flags, TYPE_PATCH),
+              buffer, 0, AUDIO_SESSION_NONE, getuid(), flags, TYPE_PATCH),
               mProxy(new ClientProxy(mCblk, mBuffer, frameCount, mFrameSize, true, true))
 {
     uint64_t mixBufferNs = ((uint64_t)2 * playbackThread->frameCount() * 1000000000) /
@@ -1345,7 +1346,7 @@
 }
 
 status_t AudioFlinger::PlaybackThread::PatchTrack::start(AudioSystem::sync_event_t event,
-                                                          int triggerSession)
+                                                          audio_session_t triggerSession)
 {
     status_t status = Track::start(event, triggerSession);
     if (status != NO_ERROR) {
@@ -1429,7 +1430,7 @@
 }
 
 status_t AudioFlinger::RecordHandle::start(int /*AudioSystem::sync_event_t*/ event,
-        int triggerSession) {
+        audio_session_t triggerSession) {
     ALOGV("RecordHandle::start()");
     return mRecordTrack->start((AudioSystem::sync_event_t)event, triggerSession);
 }
@@ -1460,7 +1461,7 @@
             audio_channel_mask_t channelMask,
             size_t frameCount,
             void *buffer,
-            int sessionId,
+            audio_session_t sessionId,
             int uid,
             IAudioFlinger::track_flags_t flags,
             track_type type)
@@ -1537,7 +1538,7 @@
 }
 
 status_t AudioFlinger::RecordThread::RecordTrack::start(AudioSystem::sync_event_t event,
-                                                        int triggerSession)
+                                                        audio_session_t triggerSession)
 {
     sp<ThreadBase> thread = mThread.promote();
     if (thread != 0) {
@@ -1554,7 +1555,7 @@
     if (thread != 0) {
         RecordThread *recordThread = (RecordThread *)thread.get();
         if (recordThread->stop(this) && isExternalTrack()) {
-            AudioSystem::stopInput(mThreadIoHandle, (audio_session_t)mSessionId);
+            AudioSystem::stopInput(mThreadIoHandle, mSessionId);
         }
     }
 }
@@ -1566,9 +1567,9 @@
     {
         if (isExternalTrack()) {
             if (mState == ACTIVE || mState == RESUMING) {
-                AudioSystem::stopInput(mThreadIoHandle, (audio_session_t)mSessionId);
+                AudioSystem::stopInput(mThreadIoHandle, mSessionId);
             }
-            AudioSystem::releaseInput(mThreadIoHandle, (audio_session_t)mSessionId);
+            AudioSystem::releaseInput(mThreadIoHandle, mSessionId);
         }
         sp<ThreadBase> thread = mThread.promote();
         if (thread != 0) {
@@ -1660,7 +1661,7 @@
                                                      void *buffer,
                                                      IAudioFlinger::track_flags_t flags)
     :   RecordTrack(recordThread, NULL, sampleRate, format, channelMask, frameCount,
-                buffer, 0, getuid(), flags, TYPE_PATCH),
+                buffer, AUDIO_SESSION_NONE, getuid(), flags, TYPE_PATCH),
                 mProxy(new ClientProxy(mCblk, mBuffer, frameCount, mFrameSize, false, true))
 {
     uint64_t mixBufferNs = ((uint64_t)2 * recordThread->frameCount() * 1000000000) /
diff --git a/services/audiopolicy/AudioPolicyInterface.h b/services/audiopolicy/AudioPolicyInterface.h
index 1c41ce1..b1347f4 100644
--- a/services/audiopolicy/AudioPolicyInterface.h
+++ b/services/audiopolicy/AudioPolicyInterface.h
@@ -312,7 +312,7 @@
     virtual status_t setVoiceVolume(float volume, int delayMs = 0) = 0;
 
     // move effect to the specified output
-    virtual status_t moveEffects(int session,
+    virtual status_t moveEffects(audio_session_t session,
                                      audio_io_handle_t srcOutput,
                                      audio_io_handle_t dstOutput) = 0;
 
diff --git a/services/audiopolicy/service/AudioPolicyClientImpl.cpp b/services/audiopolicy/service/AudioPolicyClientImpl.cpp
index f1c0d1a..08f9cc1 100644
--- a/services/audiopolicy/service/AudioPolicyClientImpl.cpp
+++ b/services/audiopolicy/service/AudioPolicyClientImpl.cpp
@@ -171,7 +171,7 @@
     return mAudioPolicyService->setVoiceVolume(volume, delay_ms);
 }
 
-status_t AudioPolicyService::AudioPolicyClient::moveEffects(int session,
+status_t AudioPolicyService::AudioPolicyClient::moveEffects(audio_session_t session,
                         audio_io_handle_t src_output,
                         audio_io_handle_t dst_output)
 {
diff --git a/services/audiopolicy/service/AudioPolicyClientImplLegacy.cpp b/services/audiopolicy/service/AudioPolicyClientImplLegacy.cpp
index a79f8ae..580d740 100644
--- a/services/audiopolicy/service/AudioPolicyClientImplLegacy.cpp
+++ b/services/audiopolicy/service/AudioPolicyClientImplLegacy.cpp
@@ -252,7 +252,7 @@
     return af->invalidateStream(stream);
 }
 
-int aps_move_effects(void *service __unused, int session,
+int aps_move_effects(void *service __unused, audio_session_t session,
                                 audio_io_handle_t src_output,
                                 audio_io_handle_t dst_output)
 {
diff --git a/services/audiopolicy/service/AudioPolicyEffects.cpp b/services/audiopolicy/service/AudioPolicyEffects.cpp
index ce77814..b732b20 100644
--- a/services/audiopolicy/service/AudioPolicyEffects.cpp
+++ b/services/audiopolicy/service/AudioPolicyEffects.cpp
@@ -79,7 +79,7 @@
 
 status_t AudioPolicyEffects::addInputEffects(audio_io_handle_t input,
                              audio_source_t inputSource,
-                             int audioSession)
+                             audio_session_t audioSession)
 {
     status_t status = NO_ERROR;
 
@@ -152,7 +152,7 @@
     return status;
 }
 
-status_t AudioPolicyEffects::queryDefaultInputEffects(int audioSession,
+status_t AudioPolicyEffects::queryDefaultInputEffects(audio_session_t audioSession,
                                                       effect_descriptor_t *descriptors,
                                                       uint32_t *count)
 {
@@ -185,7 +185,7 @@
 }
 
 
-status_t AudioPolicyEffects::queryDefaultOutputSessionEffects(int audioSession,
+status_t AudioPolicyEffects::queryDefaultOutputSessionEffects(audio_session_t audioSession,
                          effect_descriptor_t *descriptors,
                          uint32_t *count)
 {
@@ -220,7 +220,7 @@
 
 status_t AudioPolicyEffects::addOutputSessionEffects(audio_io_handle_t output,
                          audio_stream_type_t stream,
-                         int audioSession)
+                         audio_session_t audioSession)
 {
     status_t status = NO_ERROR;
 
@@ -275,7 +275,7 @@
 
 status_t AudioPolicyEffects::releaseOutputSessionEffects(audio_io_handle_t output,
                          audio_stream_type_t stream,
-                         int audioSession)
+                         audio_session_t audioSession)
 {
     status_t status = NO_ERROR;
     (void) output; // argument not used for now
diff --git a/services/audiopolicy/service/AudioPolicyEffects.h b/services/audiopolicy/service/AudioPolicyEffects.h
index 266a45e..ee9bd50 100644
--- a/services/audiopolicy/service/AudioPolicyEffects.h
+++ b/services/audiopolicy/service/AudioPolicyEffects.h
@@ -51,7 +51,7 @@
 
     // Return a list of effect descriptors for default input effects
     // associated with audioSession
-    status_t queryDefaultInputEffects(int audioSession,
+    status_t queryDefaultInputEffects(audio_session_t audioSession,
                              effect_descriptor_t *descriptors,
                              uint32_t *count);
 
@@ -59,7 +59,7 @@
     // Effects are attached depending on the audio_source_t
     status_t addInputEffects(audio_io_handle_t input,
                              audio_source_t inputSource,
-                             int audioSession);
+                             audio_session_t audioSession);
 
     // Add all input effects associated to this input
     status_t releaseInputEffects(audio_io_handle_t input);
@@ -67,7 +67,7 @@
 
     // Return a list of effect descriptors for default output effects
     // associated with audioSession
-    status_t queryDefaultOutputSessionEffects(int audioSession,
+    status_t queryDefaultOutputSessionEffects(audio_session_t audioSession,
                              effect_descriptor_t *descriptors,
                              uint32_t *count);
 
@@ -75,12 +75,12 @@
     // Effects are attached depending on the audio_stream_type_t
     status_t addOutputSessionEffects(audio_io_handle_t output,
                              audio_stream_type_t stream,
-                             int audioSession);
+                             audio_session_t audioSession);
 
     // release all output effects associated with this output stream and audiosession
     status_t releaseOutputSessionEffects(audio_io_handle_t output,
                              audio_stream_type_t stream,
-                             int audioSession);
+                             audio_session_t audioSession);
 
 private:
 
@@ -135,13 +135,13 @@
     // class to store voctor of AudioEffects
     class EffectVector {
     public:
-        EffectVector(int session) : mSessionId(session), mRefCount(0) {}
+        EffectVector(audio_session_t session) : mSessionId(session), mRefCount(0) {}
         /*virtual*/ ~EffectVector() {}
 
         // Enable or disable all effects in effect vector
         void setProcessorEnabled(bool enabled);
 
-        const int mSessionId;
+        const audio_session_t mSessionId;
         // AudioPolicyManager keeps mLock, no need for lock on reference count here
         int mRefCount;
         Vector< sp<AudioEffect> >mEffects;
@@ -188,7 +188,7 @@
     // Automatic output effects are organized per audio_stream_type_t
     KeyedVector< audio_stream_type_t, EffectDescVector* > mOutputStreams;
     // Automatic output effects are unique for audiosession ID
-    KeyedVector< int32_t, EffectVector* > mOutputSessions;
+    KeyedVector< audio_session_t, EffectVector* > mOutputSessions;
 };
 
 }; // namespace android
diff --git a/services/audiopolicy/service/AudioPolicyInterfaceImpl.cpp b/services/audiopolicy/service/AudioPolicyInterfaceImpl.cpp
index fdd6dd2..92a1285 100644
--- a/services/audiopolicy/service/AudioPolicyInterfaceImpl.cpp
+++ b/services/audiopolicy/service/AudioPolicyInterfaceImpl.cpp
@@ -476,7 +476,7 @@
 status_t AudioPolicyService::registerEffect(const effect_descriptor_t *desc,
                                 audio_io_handle_t io,
                                 uint32_t strategy,
-                                int session,
+                                audio_session_t session,
                                 int id)
 {
     if (mAudioPolicyManager == NULL) {
@@ -537,7 +537,7 @@
     return mAudioPolicyManager->isSourceActive(source);
 }
 
-status_t AudioPolicyService::queryDefaultPreProcessing(int audioSession,
+status_t AudioPolicyService::queryDefaultPreProcessing(audio_session_t audioSession,
                                                        effect_descriptor_t *descriptors,
                                                        uint32_t *count)
 {
diff --git a/services/audiopolicy/service/AudioPolicyInterfaceImplLegacy.cpp b/services/audiopolicy/service/AudioPolicyInterfaceImplLegacy.cpp
index 08b2a3b..c830454 100644
--- a/services/audiopolicy/service/AudioPolicyInterfaceImplLegacy.cpp
+++ b/services/audiopolicy/service/AudioPolicyInterfaceImplLegacy.cpp
@@ -427,7 +427,7 @@
 status_t AudioPolicyService::registerEffect(const effect_descriptor_t *desc,
                                 audio_io_handle_t io,
                                 uint32_t strategy,
-                                int session,
+                                audio_session_t session,
                                 int id)
 {
     if (mpAudioPolicy == NULL) {
@@ -488,7 +488,7 @@
     return mpAudioPolicy->is_source_active(mpAudioPolicy, source);
 }
 
-status_t AudioPolicyService::queryDefaultPreProcessing(int audioSession,
+status_t AudioPolicyService::queryDefaultPreProcessing(audio_session_t audioSession,
                                                        effect_descriptor_t *descriptors,
                                                        uint32_t *count)
 {
diff --git a/services/audiopolicy/service/AudioPolicyService.cpp b/services/audiopolicy/service/AudioPolicyService.cpp
index 94e0701..a6cd50e 100644
--- a/services/audiopolicy/service/AudioPolicyService.cpp
+++ b/services/audiopolicy/service/AudioPolicyService.cpp
@@ -1182,7 +1182,7 @@
                                                   audio_channel_mask_t *pChannelMask);
 int aps_close_input(void *service __unused, audio_io_handle_t input);
 int aps_invalidate_stream(void *service __unused, audio_stream_type_t stream);
-int aps_move_effects(void *service __unused, int session,
+int aps_move_effects(void *service __unused, audio_session_t session,
                                 audio_io_handle_t src_output,
                                 audio_io_handle_t dst_output);
 char * aps_get_parameters(void *service __unused, audio_io_handle_t io_handle,
diff --git a/services/audiopolicy/service/AudioPolicyService.h b/services/audiopolicy/service/AudioPolicyService.h
index cecd617..2710ac7 100644
--- a/services/audiopolicy/service/AudioPolicyService.h
+++ b/services/audiopolicy/service/AudioPolicyService.h
@@ -128,7 +128,7 @@
     virtual status_t registerEffect(const effect_descriptor_t *desc,
                                     audio_io_handle_t io,
                                     uint32_t strategy,
-                                    int session,
+                                    audio_session_t session,
                                     int id);
     virtual status_t unregisterEffect(int id);
     virtual status_t setEffectEnabled(int id, bool enabled);
@@ -136,7 +136,7 @@
     virtual bool isStreamActiveRemotely(audio_stream_type_t stream, uint32_t inPastMs = 0) const;
     virtual bool isSourceActive(audio_source_t source) const;
 
-    virtual status_t queryDefaultPreProcessing(int audioSession,
+    virtual status_t queryDefaultPreProcessing(audio_session_t audioSession,
                                               effect_descriptor_t *descriptors,
                                               uint32_t *count);
     virtual     status_t    onTransact(
@@ -498,7 +498,7 @@
         virtual status_t setVoiceVolume(float volume, int delayMs = 0);
 
         // move effect to the specified output
-        virtual status_t moveEffects(int session,
+        virtual status_t moveEffects(audio_session_t session,
                                          audio_io_handle_t srcOutput,
                                          audio_io_handle_t dstOutput);