commit 9806710f5d6722cfc5783c7eca3512451a0f2035
author Glenn Kasten <gkasten@google.com> Tue Dec 13 11:47:54 2011 -0800
committer Glenn Kasten <gkasten@google.com> Fri Jan 13 15:53:10 2012 -0800
tree c0fb62e5d69389a3f31812a63ca90a76c7d6ab0e
parent 09192653e836b21689f004bf8dee375356641181

Fix locking for mMasterVolume and mMute

mMasterVolume and mMute are both protected by mutex in AudioFlinger class, but
there were two places where they were accessed without a mutex.

Also make AudioFlinger::mMasterMute private not protected.

Change-Id: Ia3897daeb5c50313df5bcc071824357526237f3e

services/audioflinger/AudioFlinger.cpp

diff --git a/services/audioflinger/AudioFlinger.cpp b/services/audioflinger/AudioFlinger.cpp
index 9fb666e..d267497 100644
--- a/services/audioflinger/AudioFlinger.cpp
+++ b/services/audioflinger/AudioFlinger.cpp
@@ -646,12 +646,14 @@
 
 float AudioFlinger::masterVolume() const
 {
-    return mMasterVolume;
+    Mutex::Autolock _l(mLock);
+    return masterVolume_l();
 }
 
 bool AudioFlinger::masterMute() const
 {
-    return mMasterMute;
+    Mutex::Autolock _l(mLock);
+    return masterMute_l();
 }
 
 status_t AudioFlinger::setStreamVolume(int stream, float value, int output)
@@ -1379,8 +1381,10 @@
 
     readOutputParameters();
 
-    mMasterVolume = mAudioFlinger->masterVolume();
-    mMasterMute = mAudioFlinger->masterMute();
+    // Assumes constructor is called by AudioFlinger with it's mLock held,
+    // but it would be safer to explicitly pass these as parameters
+    mMasterVolume = mAudioFlinger->masterVolume_l();
+    mMasterMute = mAudioFlinger->masterMute_l();
 
     for (int stream = 0; stream < AUDIO_STREAM_CNT; stream++) {
         mStreamTypes[stream].volume = mAudioFlinger->streamVolumeInternal(stream);

services/audioflinger/AudioFlinger.h

diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index f99e764..d22de26 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -765,7 +765,9 @@
         int16_t*                        mMixBuffer;
         int                             mSuspended;
         int                             mBytesWritten;
+    private:
         bool                            mMasterMute;
+    protected:
         SortedVector< wp<Track> >       mActiveTracks;
 
         virtual int             getTrackName_l() = 0;
@@ -1388,6 +1390,8 @@
 
                 DefaultKeyedVector< int, sp<PlaybackThread> >  mPlaybackThreads;
                 PlaybackThread::stream_type_t       mStreamTypes[AUDIO_STREAM_CNT];
+
+                // both are protected by mLock
                 float                               mMasterVolume;
                 bool                                mMasterMute;
 
@@ -1399,6 +1403,9 @@
                 bool                                mBtNrecIsOff;
 
                 Vector<AudioSessionRef*> mAudioSessionRefs;
+
+                float       masterVolume_l() const  { return mMasterVolume; }
+                bool        masterMute_l() const    { return mMasterMute; }
 };