Fix races related to volume and mute

Fix race conditions when setting master volume, master mute, stream
volume, stream mute for a playback thread, and when reading stream
volume of a playback thread.  Lock order is AudioFlinger, then thread.

Rename streamVolumeInternal to streamVolume_l, comment, and use it to
implement streamVolume().

Code size reduction:
 - Remove dead code: AudioFlinger::PlaybackThread::masterVolume, masterMute, streamMute.
 - Change return type of non-binder methods that always succeed from status_t to void.
 - Remove virtual from volume and mute methods that don't need it.

This change saves 228 bytes but decreases performance of binder operations
due to the added locks.

Change-Id: Iac75abc1f54784873a667d1981b2e08f8f31e5c9

2 files changed, 31 insertions, 31 deletions

diff --git a/services/audioflinger/AudioFlinger.cpp b/services/audioflinger/AudioFlinger.cpp
index 93c91fb..4cf570c 100644
--- a/services/audioflinger/AudioFlinger.cpp
+++ b/services/audioflinger/AudioFlinger.cpp
@@ -729,7 +729,7 @@ float AudioFlinger::streamVolume(audio_stream_type_t stream, audio_io_handle_t o
         }
         volume = thread->streamVolume(stream);
     } else {
-        volume = mStreamTypes[stream].volume;
+        volume = streamVolume_l(stream);
     }
 
     return volume;
@@ -741,7 +741,8 @@ bool AudioFlinger::streamMute(audio_stream_type_t stream) const
         return true;
     }
 
-    return mStreamTypes[stream].mute;
+    AutoMutex lock(mLock);
+    return streamMute_l(stream);
 }
 
 status_t AudioFlinger::setParameters(audio_io_handle_t ioHandle, const String8& keyValuePairs)
@@ -1383,11 +1384,13 @@ AudioFlinger::PlaybackThread::PlaybackThread(const sp<AudioFlinger>& audioFlinge
     // There is no AUDIO_STREAM_MIN, and ++ operator does not compile
     for (audio_stream_type_t stream = (audio_stream_type_t) 0; stream < AUDIO_STREAM_CNT;
             stream = (audio_stream_type_t) (stream + 1)) {
-        mStreamTypes[stream].volume = mAudioFlinger->streamVolumeInternal(stream);
-        mStreamTypes[stream].mute = mAudioFlinger->streamMute(stream);
+        mStreamTypes[stream].volume = mAudioFlinger->streamVolume_l(stream);
+        mStreamTypes[stream].mute = mAudioFlinger->streamMute_l(stream);
         // initialized by stream_type_t default constructor
         // mStreamTypes[stream].valid = true;
     }
+    // mStreamTypes[AUDIO_STREAM_CNT] exists but isn't explicitly initialized here,
+    // because mAudioFlinger doesn't have one to copy from
 }
 
 AudioFlinger::PlaybackThread::~PlaybackThread()
@@ -1582,40 +1585,36 @@ uint32_t AudioFlinger::PlaybackThread::latency() const
     }
 }
 
-status_t AudioFlinger::PlaybackThread::setMasterVolume(float value)
+void AudioFlinger::PlaybackThread::setMasterVolume(float value)
 {
+    Mutex::Autolock _l(mLock);
     mMasterVolume = value;
-    return NO_ERROR;
 }
 
-status_t AudioFlinger::PlaybackThread::setMasterMute(bool muted)
+void AudioFlinger::PlaybackThread::setMasterMute(bool muted)
 {
-    mMasterMute = muted;
-    return NO_ERROR;
+    Mutex::Autolock _l(mLock);
+    setMasterMute_l(muted);
 }
 
-status_t AudioFlinger::PlaybackThread::setStreamVolume(audio_stream_type_t stream, float value)
+void AudioFlinger::PlaybackThread::setStreamVolume(audio_stream_type_t stream, float value)
 {
+    Mutex::Autolock _l(mLock);
     mStreamTypes[stream].volume = value;
-    return NO_ERROR;
 }
 
-status_t AudioFlinger::PlaybackThread::setStreamMute(audio_stream_type_t stream, bool muted)
+void AudioFlinger::PlaybackThread::setStreamMute(audio_stream_type_t stream, bool muted)
 {
+    Mutex::Autolock _l(mLock);
     mStreamTypes[stream].mute = muted;
-    return NO_ERROR;
 }
 
 float AudioFlinger::PlaybackThread::streamVolume(audio_stream_type_t stream) const
 {
+    Mutex::Autolock _l(mLock);
     return mStreamTypes[stream].volume;
 }
 
-bool AudioFlinger::PlaybackThread::streamMute(audio_stream_type_t stream) const
-{
-    return mStreamTypes[stream].mute;
-}
-
 // addTrack_l() must be called with ThreadBase::mLock held
 status_t AudioFlinger::PlaybackThread::addTrack_l(const sp<Track>& track)
 {
@@ -1945,7 +1944,7 @@ bool AudioFlinger::MixerThread::threadLoop()
                         property_get("ro.audio.silent", value, "0");
                         if (atoi(value)) {
                             ALOGD("Silence is golden");
-                            setMasterMute(true);
+                            setMasterMute_l(true);
                         }
                     }
 
@@ -2661,7 +2660,7 @@ bool AudioFlinger::DirectOutputThread::threadLoop()
                         property_get("ro.audio.silent", value, "0");
                         if (atoi(value)) {
                             ALOGD("Silence is golden");
-                            setMasterMute(true);
+                            setMasterMute_l(true);
                         }
                     }
 
@@ -3057,7 +3056,7 @@ bool AudioFlinger::DuplicatingThread::threadLoop()
                         property_get("ro.audio.silent", value, "0");
                         if (atoi(value)) {
                             ALOGD("Silence is golden");
-                            setMasterMute(true);
+                            setMasterMute_l(true);
                         }
                     }
 
diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index 97103c4..674b047 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -710,17 +710,13 @@ private:
 
         virtual     uint32_t    latency() const;
 
-        virtual     status_t    setMasterVolume(float value);
-        virtual     status_t    setMasterMute(bool muted);
+                    void        setMasterVolume(float value);
+                    void        setMasterMute(bool muted);
 
-        virtual     float       masterVolume() const { return mMasterVolume; }
-        virtual     bool        masterMute() const { return mMasterMute; }
+                    void        setStreamVolume(audio_stream_type_t stream, float value);
+                    void        setStreamMute(audio_stream_type_t stream, bool muted);
 
-        virtual     status_t    setStreamVolume(audio_stream_type_t stream, float value);
-        virtual     status_t    setStreamMute(audio_stream_type_t stream, bool muted);
-
-        virtual     float       streamVolume(audio_stream_type_t stream) const;
-        virtual     bool        streamMute(audio_stream_type_t stream) const;
+                    float       streamVolume(audio_stream_type_t stream) const;
 
                     sp<Track>   createTrack_l(
                                     const sp<AudioFlinger::Client>& client,
@@ -776,6 +772,7 @@ private:
         int                             mBytesWritten;
     private:
         bool                            mMasterMute;
+                    void        setMasterMute_l(bool muted) { mMasterMute = muted; }
     protected:
         SortedVector< wp<Track> >       mActiveTracks;
 
@@ -899,7 +896,11 @@ private:
               PlaybackThread *checkPlaybackThread_l(audio_io_handle_t output) const;
               MixerThread *checkMixerThread_l(audio_io_handle_t output) const;
               RecordThread *checkRecordThread_l(audio_io_handle_t input) const;
-              float streamVolumeInternal(audio_stream_type_t stream) const
+              // no range check, AudioFlinger::mLock held
+              bool streamMute_l(audio_stream_type_t stream) const
+                                { return mStreamTypes[stream].mute; }
+              // no range check, doesn't check per-thread stream volume, AudioFlinger::mLock held
+              float streamVolume_l(audio_stream_type_t stream) const
                                 { return mStreamTypes[stream].volume; }
               void audioConfigChanged_l(int event, audio_io_handle_t ioHandle, void *param2);