From 27876c02c21cd3ab7ef01bdd1fc5400c5143584a Mon Sep 17 00:00:00 2001 From: Andy Hung Date: Tue, 9 Sep 2014 18:07:55 -0700 Subject: Prevent stopped audio tracks from mixing data Static tracks should have zero framesReady when stopping or stopped, to prevent mixer from running potentially indefinitely with loop mode. Bug: 16070883 Change-Id: Iab9968044d1a6f8543bbcbfb246f49f27d68cace --- services/audioflinger/Tracks.cpp | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) (limited to 'services/audioflinger/Tracks.cpp') diff --git a/services/audioflinger/Tracks.cpp b/services/audioflinger/Tracks.cpp index b9308fa..037c73b 100644 --- a/services/audioflinger/Tracks.cpp +++ b/services/audioflinger/Tracks.cpp @@ -611,15 +611,16 @@ status_t AudioFlinger::PlaybackThread::Track::getNextBuffer( // ExtendedAudioBufferProvider interface -// Note that framesReady() takes a mutex on the control block using tryLock(). -// This could result in priority inversion if framesReady() is called by the normal mixer, -// as the normal mixer thread runs at lower -// priority than the client's callback thread: there is a short window within framesReady() -// during which the normal mixer could be preempted, and the client callback would block. -// Another problem can occur if framesReady() is called by the fast mixer: -// the tryLock() could block for up to 1 ms, and a sequence of these could delay fast mixer. -// FIXME Replace AudioTrackShared control block implementation by a non-blocking FIFO queue. +// framesReady() may return an approximation of the number of frames if called +// from a different thread than the one calling Proxy->obtainBuffer() and +// Proxy->releaseBuffer(). Also note there is no mutual exclusion in the +// AudioTrackServerProxy so be especially careful calling with FastTracks. size_t AudioFlinger::PlaybackThread::Track::framesReady() const { + if (mSharedBuffer != 0 && (isStopped() || isStopping())) { + // Static tracks return zero frames immediately upon stopping (for FastTracks). + // The remainder of the buffer is not drained. + return 0; + } return mAudioTrackServerProxy->framesReady(); } -- cgit v1.1