From 5c8b18c90806307939fd44c57855621ab004af8a Mon Sep 17 00:00:00 2001
From: Alec Mouri <alecmouri@google.com>
Date: Thu, 19 Aug 2021 16:52:34 -0700
Subject: 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 | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'libs/gui/BLASTBufferQueue.cpp')

diff --git a/libs/gui/BLASTBufferQueue.cpp b/libs/gui/BLASTBufferQueue.cpp
index 56a9683773..d860f30617 100644
--- a/libs/gui/BLASTBufferQueue.cpp
+++ b/libs/gui/BLASTBufferQueue.cpp
@@ -118,12 +118,12 @@ void BLASTBufferItemConsumer::getConnectionEvents(uint64_t frameNumber, bool* ne
 }
 
 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);
-- 
cgit v1.2.3-59-g8ed1b