diff --git a/services/audioflinger/AudioFlinger.cpp b/services/audioflinger/AudioFlinger.cpp
index 2b08ab5..2702242 100644
--- a/services/audioflinger/AudioFlinger.cpp
+++ b/services/audioflinger/AudioFlinger.cpp
@@ -1738,7 +1738,10 @@
                     LOGV("BUFFER TIMEOUT: remove(%d) from active list on thread %p", track->name(), this);
                     tracksToRemove->add(track);
                     // indicate to client process that the track was disabled because of underrun
-                    cblk->flags |= CBLK_DISABLED_ON;
+                    {
+                        AutoMutex _l(cblk->lock);
+                        cblk->flags |= CBLK_DISABLED_ON;
+                    }
                 } else if (mixerStatus != MIXER_TRACKS_READY) {
                     mixerStatus = MIXER_TRACKS_ENABLED;
                 }
@@ -1787,10 +1790,9 @@
     for (size_t i = 0; i < size; i++) {
         sp<Track> t = mTracks[i];
         if (t->type() == streamType) {
-            t->mCblk->lock.lock();
+            AutoMutex _lcblk(t->mCblk->lock);
             t->mCblk->flags |= CBLK_INVALID_ON;
             t->mCblk->cv.signal();
-            t->mCblk->lock.unlock();
         }
     }
 }
@@ -2948,6 +2950,7 @@
 
     if (mCblk->framesReady() >= mCblk->frameCount ||
             (mCblk->flags & CBLK_FORCEREADY_MSK)) {
+        AutoMutex _l(mCblk->lock);
         mFillingUpStatus = FS_FILLED;
         mCblk->flags &= ~CBLK_FORCEREADY_MSK;
         return true;
@@ -3063,19 +3066,18 @@
         // STOPPED state
         mState = STOPPED;
 
-        mCblk->lock.lock();
         // NOTE: reset() will reset cblk->user and cblk->server with
         // the risk that at the same time, the AudioMixer is trying to read
         // data. In this case, getNextBuffer() would return a NULL pointer
         // as audio buffer => the AudioMixer code MUST always test that pointer
         // returned by getNextBuffer() is not NULL!
         reset();
-        mCblk->lock.unlock();
     }
 }
 
 void AudioFlinger::PlaybackThread::Track::reset()
 {
+    AutoMutex _l(mCblk->lock);
     // Do not reset twice to avoid discarding data written just after a flush and before
     // the audioflinger thread detects the track is stopped.
     if (!mResetDone) {
@@ -3209,10 +3211,13 @@
     if (thread != 0) {
         RecordThread *recordThread = (RecordThread *)thread.get();
         recordThread->stop(this);
-        TrackBase::reset();
-        // Force overerrun condition to avoid false overrun callback until first data is
-        // read from buffer
-        mCblk->flags |= CBLK_UNDERRUN_ON;
+        {
+            AutoMutex _l(mCblk->lock);
+            TrackBase::reset();
+            // Force overerrun condition to avoid false overrun callback until first data is
+            // read from buffer
+            mCblk->flags |= CBLK_UNDERRUN_ON;
+        }
     }
 }