commit 6637baae4244aec731c4014da72418d330636ae1
author Glenn Kasten <gkasten@google.com> Mon Jan 09 09:40:36 2012 -0800
committer Glenn Kasten <gkasten@google.com> Wed Feb 08 17:01:49 2012 -0800
tree 5244135379ecfdd8ce7394ccfed0b363ccabcf56
parent 98ec94c5854daccc3474758524e7f4adfe535ce0

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

services/audioflinger/AudioFlinger.h

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 @@
 
         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 @@
         int                             mBytesWritten;
     private:
         bool                            mMasterMute;
+                    void        setMasterMute_l(bool muted) { mMasterMute = muted; }
     protected:
         SortedVector< wp<Track> >       mActiveTracks;
 
@@ -899,7 +896,11 @@
               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);