commit e0f5ec5a2541a4af92479c1e059ea298545ce08a
author Andy Hung <hunga@google.com> Wed Aug 30 11:26:06 2023 -0700
committer Andy Hung <hunga@google.com> Wed Sep 06 19:52:26 2023 -0700
tree 108dff69d40af4346e8b6830b779d53ba53717ac
parent c5007f85ec1501d2c627c3f1bbe0480881d567be

AudioFlinger: Use scoped_lock to prevent deadlock

Test: atest AudioTrackTest AudioRecordTest
Test: atest AAudioTests AudioTrackOffloadTest
Test: atest AudioPlaybackCaptureTest
Test: Camera YouTube
Bug: 282945023
Change-Id: I63906b09dcee8ed18202520aa5e823ec2362a327

services/audioflinger/AudioFlinger.cpp

diff --git a/services/audioflinger/AudioFlinger.cpp b/services/audioflinger/AudioFlinger.cpp
index 43163f2..b0348ad 100644
--- a/services/audioflinger/AudioFlinger.cpp
+++ b/services/audioflinger/AudioFlinger.cpp
@@ -3026,8 +3026,8 @@
                         checkPlaybackThread_l(mPlaybackThreads.keyAt(0));
                 if (dstThread != NULL) {
                     // audioflinger lock is held so order of thread lock acquisition doesn't matter
-                    audio_utils::lock_guard _dl(dstThread->mutex());
-                    audio_utils::lock_guard _sl(playbackThread->mutex());
+                    // Use scoped_lock to avoid deadlock order issues with duplicating threads.
+                    audio_utils::scoped_lock sl(dstThread->mutex(), playbackThread->mutex());
                     Vector<sp<IAfEffectChain>> effectChains = playbackThread->getEffectChains_l();
                     for (size_t i = 0; i < effectChains.size(); i ++) {
                         moveEffectChain_l(effectChains[i]->sessionId(), playbackThread.get(),
@@ -4342,8 +4342,7 @@
         return BAD_VALUE;
     }
 
-    audio_utils::lock_guard _dl(dstThread->mutex());
-    audio_utils::lock_guard _sl(srcThread->mutex());
+    audio_utils::scoped_lock _ll(dstThread->mutex(), srcThread->mutex());
     return moveEffectChain_l(sessionId, srcThread, dstThread);
 }
 
@@ -4525,8 +4524,7 @@
     const sp<IAfPlaybackThread> thread = threadBase ? threadBase->asIAfPlaybackThread() : nullptr;
 
     if (EffectId != 0 && thread != 0 && dstThread != thread.get()) {
-        audio_utils::lock_guard _dl(dstThread->mutex());
-        audio_utils::lock_guard _sl(thread->mutex());
+        audio_utils::scoped_lock _ll(dstThread->mutex(), thread->mutex());
         sp<IAfEffectChain> srcChain = thread->getEffectChain_l(AUDIO_SESSION_OUTPUT_MIX);
         sp<IAfEffectChain> dstChain;
         if (srcChain == 0) {