commit 5c8b18c90806307939fd44c57855621ab004af8a
author Alec Mouri <alecmouri@google.com> Thu Aug 19 16:52:34 2021 -0700
committer Ady Abraham <adyabr@google.com> Tue Aug 31 21:22:57 2021 +0000
tree eb969890954c4a049b3967c87b5c3748fee1a376
parent 66a59c3ebfa3572f11758731cda7296541767b5e

Use a separate mutex for BLASTBufferQueue in BLASTBufferItemConsumer

Avoids the following deadlock...

Thread 1:
* BLASTBufferQueue::transactionCallback acquires
BLASTBufferQueue::mMutex
* BLASTBufferItemConsumer::updateFrameTimestamps waits to
acquire BLASTBufferItemConsumer::mMutex

Thread 2:
* BLASTBufferItemConsumer::onSidebandStreamChanged acquires
BLASTBufferItemConsumer::mMutex
*  BLASTBufferQueue::setSidebandStream tries to acquire
BLASTBufferQueue::mMutex

Bug: 192998815
Test: Both CTS Media and Mediav2 (by partner)
Change-Id: I37523031841db3f1a29481bbfa76d6c028a6942e

libs/gui/BLASTBufferQueue.cpp

diff --git a/libs/gui/BLASTBufferQueue.cpp b/libs/gui/BLASTBufferQueue.cpp
index 56a9683..d860f30 100644
--- a/libs/gui/BLASTBufferQueue.cpp
+++ b/libs/gui/BLASTBufferQueue.cpp
@@ -118,12 +118,12 @@
 }
 
 void BLASTBufferItemConsumer::setBlastBufferQueue(BLASTBufferQueue* blastbufferqueue) {
-    Mutex::Autolock lock(mMutex);
+    std::scoped_lock lock(mBufferQueueMutex);
     mBLASTBufferQueue = blastbufferqueue;
 }
 
 void BLASTBufferItemConsumer::onSidebandStreamChanged() {
-    Mutex::Autolock lock(mMutex);
+    std::scoped_lock lock(mBufferQueueMutex);
     if (mBLASTBufferQueue != nullptr) {
         sp<NativeHandle> stream = getSidebandStream();
         mBLASTBufferQueue->setSidebandStream(stream);