AudioTrack and AudioRecord: add stopAndJoinCallbacks()
Explicitly force callbacks to stop running.
This is needed to prevent a race condition with
the callbacks running after a close.
Bug: 164411271
Bug: 143305727
Bug: 182954108
Test: atest CtsNativeMediaAAudioTestCases
Test: libaaudio/tests/test_callback_race.cpp
Change-Id: Ia86c758d7f1c281a5d933bc384283440e1f1a756
diff --git a/media/libaaudio/src/legacy/AudioStreamRecord.cpp b/media/libaaudio/src/legacy/AudioStreamRecord.cpp
index 7733a04..e3ac6ff 100644
--- a/media/libaaudio/src/legacy/AudioStreamRecord.cpp
+++ b/media/libaaudio/src/legacy/AudioStreamRecord.cpp
@@ -308,11 +308,19 @@
}
void AudioStreamRecord::close_l() {
+ // The callbacks are normally joined in the AudioRecord destructor.
+ // But if another object has a reference to the AudioRecord then
+ // it will not get deleted here.
+ // So we should join callbacks explicitly before returning.
+ // Unlock around the join to avoid deadlocks if the callback tries to lock.
+ // This can happen if the callback returns AAUDIO_CALLBACK_RESULT_STOP
+ mStreamLock.unlock();
+ mAudioRecord->stopAndJoinCallbacks();
+ mStreamLock.lock();
+
mAudioRecord.clear();
- // Do not close mFixedBlockWriter because a data callback
- // thread might still be running if someone else has a reference
- // to mAudioRecord.
- // It has a unique_ptr to its buffer so it will clean up by itself.
+ // Do not close mFixedBlockReader. It has a unique_ptr to its buffer
+ // so it will clean up by itself.
AudioStream::close_l();
}
diff --git a/media/libaaudio/src/legacy/AudioStreamTrack.cpp b/media/libaaudio/src/legacy/AudioStreamTrack.cpp
index 142a85c..df97658 100644
--- a/media/libaaudio/src/legacy/AudioStreamTrack.cpp
+++ b/media/libaaudio/src/legacy/AudioStreamTrack.cpp
@@ -259,12 +259,18 @@
}
void AudioStreamTrack::close_l() {
- // Stop callbacks before deleting mFixedBlockReader memory.
+ // The callbacks are normally joined in the AudioTrack destructor.
+ // But if another object has a reference to the AudioTrack then
+ // it will not get deleted here.
+ // So we should join callbacks explicitly before returning.
+ // Unlock around the join to avoid deadlocks if the callback tries to lock.
+ // This can happen if the callback returns AAUDIO_CALLBACK_RESULT_STOP
+ mStreamLock.unlock();
+ mAudioTrack->stopAndJoinCallbacks();
+ mStreamLock.lock();
mAudioTrack.clear();
- // Do not close mFixedBlockReader because a data callback
- // thread might still be running if someone else has a reference
- // to mAudioRecord.
- // It has a unique_ptr to its buffer so it will clean up by itself.
+ // Do not close mFixedBlockReader. It has a unique_ptr to its buffer
+ // so it will clean up by itself.
AudioStream::close_l();
}
diff --git a/media/libaudioclient/AudioRecord.cpp b/media/libaudioclient/AudioRecord.cpp
index e15ef3d..90f6f41 100644
--- a/media/libaudioclient/AudioRecord.cpp
+++ b/media/libaudioclient/AudioRecord.cpp
@@ -181,21 +181,9 @@
.set(AMEDIAMETRICS_PROP_STATUS, (int32_t)mStatus)
.record();
+ stopAndJoinCallbacks(); // checks mStatus
+
if (mStatus == NO_ERROR) {
- // Make sure that callback function exits in the case where
- // it is looping on buffer empty condition in obtainBuffer().
- // Otherwise the callback thread will never exit.
- stop();
- if (mAudioRecordThread != 0) {
- mProxy->interrupt();
- mAudioRecordThread->requestExit(); // see comment in AudioRecord.h
- mAudioRecordThread->requestExitAndWait();
- mAudioRecordThread.clear();
- }
- // No lock here: worst case we remove a NULL callback which will be a nop
- if (mDeviceCallback != 0 && mInput != AUDIO_IO_HANDLE_NONE) {
- AudioSystem::removeAudioDeviceCallback(this, mInput, mPortId);
- }
IInterface::asBinder(mAudioRecord)->unlinkToDeath(mDeathNotifier, this);
mAudioRecord.clear();
mCblkMemory.clear();
@@ -208,6 +196,27 @@
}
}
+void AudioRecord::stopAndJoinCallbacks() {
+ // Prevent nullptr crash if it did not open properly.
+ if (mStatus != NO_ERROR) return;
+
+ // Make sure that callback function exits in the case where
+ // it is looping on buffer empty condition in obtainBuffer().
+ // Otherwise the callback thread will never exit.
+ stop();
+ if (mAudioRecordThread != 0) {
+ mProxy->interrupt();
+ mAudioRecordThread->requestExit(); // see comment in AudioRecord.h
+ mAudioRecordThread->requestExitAndWait();
+ mAudioRecordThread.clear();
+ }
+ // No lock here: worst case we remove a NULL callback which will be a nop
+ if (mDeviceCallback != 0 && mInput != AUDIO_IO_HANDLE_NONE) {
+ // This may not stop all of these device callbacks!
+ // TODO: Add some sort of protection.
+ AudioSystem::removeAudioDeviceCallback(this, mInput, mPortId);
+ }
+}
status_t AudioRecord::set(
audio_source_t inputSource,
uint32_t sampleRate,
diff --git a/media/libaudioclient/AudioTrack.cpp b/media/libaudioclient/AudioTrack.cpp
index 6c9e85c..1bc3baa 100644
--- a/media/libaudioclient/AudioTrack.cpp
+++ b/media/libaudioclient/AudioTrack.cpp
@@ -327,21 +327,9 @@
.set(AMEDIAMETRICS_PROP_STATUS, (int32_t)mStatus)
.record();
+ stopAndJoinCallbacks(); // checks mStatus
+
if (mStatus == NO_ERROR) {
- // Make sure that callback function exits in the case where
- // it is looping on buffer full condition in obtainBuffer().
- // Otherwise the callback thread will never exit.
- stop();
- if (mAudioTrackThread != 0) {
- mProxy->interrupt();
- mAudioTrackThread->requestExit(); // see comment in AudioTrack.h
- mAudioTrackThread->requestExitAndWait();
- mAudioTrackThread.clear();
- }
- // No lock here: worst case we remove a NULL callback which will be a nop
- if (mDeviceCallback != 0 && mOutput != AUDIO_IO_HANDLE_NONE) {
- AudioSystem::removeAudioDeviceCallback(this, mOutput, mPortId);
- }
IInterface::asBinder(mAudioTrack)->unlinkToDeath(mDeathNotifier, this);
mAudioTrack.clear();
mCblkMemory.clear();
@@ -355,6 +343,29 @@
}
}
+void AudioTrack::stopAndJoinCallbacks() {
+ // Prevent nullptr crash if it did not open properly.
+ if (mStatus != NO_ERROR) return;
+
+ // Make sure that callback function exits in the case where
+ // it is looping on buffer full condition in obtainBuffer().
+ // Otherwise the callback thread will never exit.
+ stop();
+ if (mAudioTrackThread != 0) { // not thread safe
+ mProxy->interrupt();
+ mAudioTrackThread->requestExit(); // see comment in AudioTrack.h
+ mAudioTrackThread->requestExitAndWait();
+ mAudioTrackThread.clear();
+ }
+ // No lock here: worst case we remove a NULL callback which will be a nop
+ if (mDeviceCallback != 0 && mOutput != AUDIO_IO_HANDLE_NONE) {
+ // This may not stop all of these device callbacks!
+ // TODO: Add some sort of protection.
+ AudioSystem::removeAudioDeviceCallback(this, mOutput, mPortId);
+ mDeviceCallback.clear();
+ }
+}
+
status_t AudioTrack::set(
audio_stream_type_t streamType,
uint32_t sampleRate,
diff --git a/media/libaudioclient/include/media/AudioRecord.h b/media/libaudioclient/include/media/AudioRecord.h
index 82a29d4..3467c3a 100644
--- a/media/libaudioclient/include/media/AudioRecord.h
+++ b/media/libaudioclient/include/media/AudioRecord.h
@@ -303,6 +303,19 @@
void stop();
bool stopped() const;
+ /* Calls stop() and then wait for all of the callbacks to return.
+ * It is safe to call this if stop() or pause() has already been called.
+ *
+ * This function is called from the destructor. But since AudioRecord
+ * is ref counted, the destructor may be called later than desired.
+ * This can be called explicitly as part of closing an AudioRecord
+ * if you want to be certain that callbacks have completely finished.
+ *
+ * This is not thread safe and should only be called from one thread,
+ * ideally as the AudioRecord is being closed.
+ */
+ void stopAndJoinCallbacks();
+
/* Return the sink sample rate for this record track in Hz.
* If specified as zero in constructor or set(), this will be the source sample rate.
* Unlike AudioTrack, the sample rate is const after initialization, so doesn't need a lock.
diff --git a/media/libaudioclient/include/media/AudioTrack.h b/media/libaudioclient/include/media/AudioTrack.h
index d167c40..c293343 100644
--- a/media/libaudioclient/include/media/AudioTrack.h
+++ b/media/libaudioclient/include/media/AudioTrack.h
@@ -479,6 +479,19 @@
void stop();
bool stopped() const;
+ /* Call stop() and then wait for all of the callbacks to return.
+ * It is safe to call this if stop() or pause() has already been called.
+ *
+ * This function is called from the destructor. But since AudioTrack
+ * is ref counted, the destructor may be called later than desired.
+ * This can be called explicitly as part of closing an AudioTrack
+ * if you want to be certain that callbacks have completely finished.
+ *
+ * This is not thread safe and should only be called from one thread,
+ * ideally as the AudioTrack is being closed.
+ */
+ void stopAndJoinCallbacks();
+
/* Flush a stopped or paused track. All previously buffered data is discarded immediately.
* This has the effect of draining the buffers without mixing or output.
* Flush is intended for streaming mode, for example before switching to non-contiguous content.