audio: Fix race condition in AudioTrack underrun.
When audio flinger mixer removes an AudioTrack from the
active list in case of underrun, it is possible that the
client has written a full buffer just after the underrun detection and
is blocked waiting for more space to write. In this case, the client
will never detect the DISABLED flag and the track never be restarted.
Also implement missing DISABLE flag detection in server side audio tracks
(OutputTrack and PatchTrack).
bug: 27567768
Change-Id: I8d0753429d4113498258b1f61bd8ac5939a612f0
diff --git a/services/audioflinger/Tracks.cpp b/services/audioflinger/Tracks.cpp
index 8b49062..0c51e81 100644
--- a/services/audioflinger/Tracks.cpp
+++ b/services/audioflinger/Tracks.cpp
@@ -1027,13 +1027,23 @@
void AudioFlinger::PlaybackThread::Track::invalidate()
{
+ signalClientFlag(CBLK_INVALID);
+ mIsInvalid = true;
+}
+
+void AudioFlinger::PlaybackThread::Track::disable()
+{
+ signalClientFlag(CBLK_DISABLED);
+}
+
+void AudioFlinger::PlaybackThread::Track::signalClientFlag(int32_t flag)
+{
// FIXME should use proxy, and needs work
audio_track_cblk_t* cblk = mCblk;
- android_atomic_or(CBLK_INVALID, &cblk->mFlags);
+ android_atomic_or(flag, &cblk->mFlags);
android_atomic_release_store(0x40000000, &cblk->mFutex);
// client is not in server, so FUTEX_WAKE is needed instead of FUTEX_WAKE_PRIVATE
(void) syscall(__NR_futex, &cblk->mFutex, FUTEX_WAKE, INT_MAX);
- mIsInvalid = true;
}
void AudioFlinger::PlaybackThread::Track::signal()
@@ -1199,7 +1209,7 @@
mOutBuffer.frameCount = pInBuffer->frameCount;
nsecs_t startTime = systemTime();
status_t status = obtainBuffer(&mOutBuffer, waitTimeLeftMs);
- if (status != NO_ERROR) {
+ if (status != NO_ERROR && status != NOT_ENOUGH_DATA) {
ALOGV("OutputTrack::write() %p thread %p no more output buffers; status %d", this,
mThread.unsafe_get(), status);
outputBufferFull = true;
@@ -1211,6 +1221,10 @@
} else {
waitTimeLeftMs = 0;
}
+ if (status == NOT_ENOUGH_DATA) {
+ restartIfDisabled();
+ continue;
+ }
}
uint32_t outFrames = pInBuffer->frameCount > mOutBuffer.frameCount ? mOutBuffer.frameCount :
@@ -1220,6 +1234,7 @@
buf.mFrameCount = outFrames;
buf.mRaw = NULL;
mClientProxy->releaseBuffer(&buf);
+ restartIfDisabled();
pInBuffer->frameCount -= outFrames;
pInBuffer->raw = (int8_t *)pInBuffer->raw + outFrames * mFrameSize;
mOutBuffer.frameCount -= outFrames;
@@ -1293,6 +1308,13 @@
mBufferQueue.clear();
}
+void AudioFlinger::PlaybackThread::OutputTrack::restartIfDisabled()
+{
+ int32_t flags = android_atomic_and(~CBLK_DISABLED, &mCblk->mFlags);
+ if (mActive && (flags & CBLK_DISABLED)) {
+ start();
+ }
+}
AudioFlinger::PlaybackThread::PatchTrack::PatchTrack(PlaybackThread *playbackThread,
audio_stream_type_t streamType,
@@ -1322,6 +1344,17 @@
{
}
+status_t AudioFlinger::PlaybackThread::PatchTrack::start(AudioSystem::sync_event_t event,
+ int triggerSession)
+{
+ status_t status = Track::start(event, triggerSession);
+ if (status != NO_ERROR) {
+ return status;
+ }
+ android_atomic_and(~CBLK_DISABLED, &mCblk->mFlags);
+ return status;
+}
+
// AudioBufferProvider interface
status_t AudioFlinger::PlaybackThread::PatchTrack::getNextBuffer(
AudioBufferProvider::Buffer* buffer)
@@ -1352,17 +1385,31 @@
status_t AudioFlinger::PlaybackThread::PatchTrack::obtainBuffer(Proxy::Buffer* buffer,
const struct timespec *timeOut)
{
- return mProxy->obtainBuffer(buffer, timeOut);
+ status_t status = NO_ERROR;
+ static const int32_t kMaxTries = 5;
+ int32_t tryCounter = kMaxTries;
+ do {
+ if (status == NOT_ENOUGH_DATA) {
+ restartIfDisabled();
+ }
+ status = mProxy->obtainBuffer(buffer, timeOut);
+ } while ((status == NOT_ENOUGH_DATA) && (tryCounter-- > 0));
+ return status;
}
void AudioFlinger::PlaybackThread::PatchTrack::releaseBuffer(Proxy::Buffer* buffer)
{
mProxy->releaseBuffer(buffer);
+ restartIfDisabled();
+ android_atomic_or(CBLK_FORCEREADY, &mCblk->mFlags);
+}
+
+void AudioFlinger::PlaybackThread::PatchTrack::restartIfDisabled()
+{
if (android_atomic_and(~CBLK_DISABLED, &mCblk->mFlags) & CBLK_DISABLED) {
ALOGW("PatchTrack::releaseBuffer() disabled due to previous underrun, restarting");
start();
}
- android_atomic_or(CBLK_FORCEREADY, &mCblk->mFlags);
}
// ----------------------------------------------------------------------------