audio flinger: handle race condition in AudioRecord creation
A rare race condition can cause a failure to create an AudioRecord if
two creation requests are processed concurrently and thread preemption happens
at a specific time within the sequence between audioflinger and
audio policy manager.
This CL implements a retry mechanism on client side when this particular failure
is detected.
Bug: 161656190
Test: Regression tests for audio capture use cases.
Test: CTS tests for AudiRecord
Change-Id: I155ee4899baeec21e10a1141cb9e323cbc8aa23b
diff --git a/media/libaudioclient/AudioRecord.cpp b/media/libaudioclient/AudioRecord.cpp
index 509e063..d6671e3 100644
--- a/media/libaudioclient/AudioRecord.cpp
+++ b/media/libaudioclient/AudioRecord.cpp
@@ -742,6 +742,8 @@
void *iMemPointer;
audio_track_cblk_t* cblk;
status_t status;
+ static const int32_t kMaxCreateAttempts = 3;
+ int32_t remainingAttempts = kMaxCreateAttempts;
if (audioFlinger == 0) {
ALOGE("%s(%d): Could not get audioflinger", __func__, mPortId);
@@ -803,15 +805,24 @@
input.sessionId = mSessionId;
originalSessionId = mSessionId;
- record = audioFlinger->createRecord(input,
- output,
- &status);
+ do {
+ record = audioFlinger->createRecord(input, output, &status);
+ if (status == NO_ERROR) {
+ break;
+ }
+ if (status != FAILED_TRANSACTION || --remainingAttempts <= 0) {
+ ALOGE("%s(%d): AudioFlinger could not create record track, status: %d",
+ __func__, mPortId, status);
+ goto exit;
+ }
+ // FAILED_TRANSACTION happens under very specific conditions causing a state mismatch
+ // between audio policy manager and audio flinger during the input stream open sequence
+ // and can be recovered by retrying.
+ // Leave time for race condition to clear before retrying and randomize delay
+ // to reduce the probability of concurrent retries in locked steps.
+ usleep((20 + rand() % 30) * 10000);
+ } while (1);
- if (status != NO_ERROR) {
- ALOGE("%s(%d): AudioFlinger could not create record track, status: %d",
- __func__, mPortId, status);
- goto exit;
- }
ALOG_ASSERT(record != 0);
// AudioFlinger now owns the reference to the I/O handle,
diff --git a/services/audioflinger/AudioFlinger.cpp b/services/audioflinger/AudioFlinger.cpp
index 34bdac5..36dc1db 100644
--- a/services/audioflinger/AudioFlinger.cpp
+++ b/services/audioflinger/AudioFlinger.cpp
@@ -2071,8 +2071,8 @@
Mutex::Autolock _l(mLock);
RecordThread *thread = checkRecordThread_l(output.inputId);
if (thread == NULL) {
- ALOGE("createRecord() checkRecordThread_l failed, input handle %d", output.inputId);
- lStatus = BAD_VALUE;
+ ALOGW("createRecord() checkRecordThread_l failed, input handle %d", output.inputId);
+ lStatus = FAILED_TRANSACTION;
goto Exit;
}
diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index affc09e..75f0743 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -7911,7 +7911,8 @@
AutoMutex lock(mLock);
if (recordTrack->isInvalid()) {
recordTrack->clearSyncStartEvent();
- return INVALID_OPERATION;
+ ALOGW("%s track %d: invalidated before startInput", __func__, recordTrack->portId());
+ return DEAD_OBJECT;
}
if (mActiveTracks.indexOf(recordTrack) >= 0) {
if (recordTrack->mState == TrackBase::PAUSING) {
@@ -7941,7 +7942,8 @@
recordTrack->mState = TrackBase::STARTING_2;
// STARTING_2 forces destroy to call stopInput.
}
- return INVALID_OPERATION;
+ ALOGW("%s track %d: invalidated after startInput", __func__, recordTrack->portId());
+ return DEAD_OBJECT;
}
if (recordTrack->mState != TrackBase::STARTING_1) {
ALOGW("%s(%d): unsynchronized mState:%d change",
diff --git a/services/audioflinger/Tracks.cpp b/services/audioflinger/Tracks.cpp
index c92bce5..ed285da 100644
--- a/services/audioflinger/Tracks.cpp
+++ b/services/audioflinger/Tracks.cpp
@@ -2229,7 +2229,8 @@
RecordThread *recordThread = (RecordThread *)thread.get();
return recordThread->start(this, event, triggerSession);
} else {
- return BAD_VALUE;
+ ALOGW("%s track %d: thread was destroyed", __func__, portId());
+ return DEAD_OBJECT;
}
}
diff --git a/services/audiopolicy/managerdefault/AudioPolicyManager.cpp b/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
index 84687fd..f8122e8 100644
--- a/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
+++ b/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
@@ -2281,7 +2281,7 @@
sp<AudioInputDescriptor> inputDesc = mInputs.getInputForClient(portId);
if (inputDesc == 0) {
ALOGW("%s no input for client %d", __FUNCTION__, portId);
- return BAD_VALUE;
+ return DEAD_OBJECT;
}
audio_io_handle_t input = inputDesc->mIoHandle;
sp<RecordClientDescriptor> client = inputDesc->getClient(portId);