opensl: bring back mutex

Change-Id: Iede9cf73b9f55e5aaa1e6d60da30362475656362

src/media/audio/opensl/audio_player.cpp

@@ -40,6 +40,8 @@ void bqPlayerCallback(SLAndroidSimpleBufferQueueItf bq, void *ctx) {
     (static_cast<AudioPlayer *>(ctx))->processSLCallback(bq);
 }
 void AudioPlayer::processSLCallback(SLAndroidSimpleBufferQueueItf bq) {
+    std::lock_guard<std::mutex> lk(m_);
+
     // retrieve the finished device buf and put onto the free queue
     // so recorder could re-use it
     sample_buf *buf;

src/media/audio/opensl/audio_player.h

@@ -58,6 +58,7 @@ public:
     void registerCallback(EngineCallback cb) {callback_ = cb;}
     size_t dbgGetDevBufCount();
 
+    std::mutex m_;
     std::atomic_bool waiting_ {false};
 };
 

src/media/audio/opensl/opensllayer.cpp

@@ -302,14 +302,14 @@ OpenSLLayer::startAudioPlayback()
         while (player_ || ringtone_) {
             playCv.wait_for(lck, std::chrono::seconds(1));
             if (player_ && player_->waiting_) {
-                //std::lock_guard<std::mutex> lk(player_->m_);
+                std::lock_guard<std::mutex> lk(player_->m_);
                 engineServicePlay(false);
                 auto n = playBufQueue_.size();
                 if (n >= PLAY_KICKSTART_BUFFER_COUNT)
                     player_->playAudioBuffers(n);
             }
             if (ringtone_ && ringtone_->waiting_) {
-                //std::lock_guard<std::mutex> lk(ringtone_->m_);
+                std::lock_guard<std::mutex> lk(ringtone_->m_);
                 engineServiceRing(false);
                 auto n = ringBufQueue_.size();
                 if (n >= PLAY_KICKSTART_BUFFER_COUNT)