From dc76ca00df27c563615d19727376c15c485c2b90 Mon Sep 17 00:00:00 2001
From: Ady Abraham <adyabr@google.com>
Date: Wed, 15 Dec 2021 11:58:56 -0800
Subject: keep a wp<BLASTBufferQueue> in BufferItemConsumer

Use a wp<> instead of raw pointer and remove the mutex around it
to prevent potential deadlocks.

Bug: 208121127
Test: stress test by partner
Change-Id: Iffed80410aeffc9b724d5c01ca2ec589c9622990
Merged-In: Iffed80410aeffc9b724d5c01ca2ec589c9622990
---
 libs/gui/BLASTBufferQueue.cpp           | 15 ++++-----------
 libs/gui/include/gui/BLASTBufferQueue.h | 10 +++++-----
 2 files changed, 9 insertions(+), 16 deletions(-)

diff --git a/libs/gui/BLASTBufferQueue.cpp b/libs/gui/BLASTBufferQueue.cpp
index 94e1ae1c74..5b59c592df 100644
--- a/libs/gui/BLASTBufferQueue.cpp
+++ b/libs/gui/BLASTBufferQueue.cpp
@@ -117,16 +117,11 @@ void BLASTBufferItemConsumer::getConnectionEvents(uint64_t frameNumber, bool* ne
     if (needsDisconnect != nullptr) *needsDisconnect = disconnect;
 }
 
-void BLASTBufferItemConsumer::setBlastBufferQueue(BLASTBufferQueue* blastbufferqueue) {
-    std::scoped_lock lock(mBufferQueueMutex);
-    mBLASTBufferQueue = blastbufferqueue;
-}
-
 void BLASTBufferItemConsumer::onSidebandStreamChanged() {
-    std::scoped_lock lock(mBufferQueueMutex);
-    if (mBLASTBufferQueue != nullptr) {
+    sp<BLASTBufferQueue> bbq = mBLASTBufferQueue.promote();
+    if (bbq != nullptr) {
         sp<NativeHandle> stream = getSidebandStream();
-        mBLASTBufferQueue->setSidebandStream(stream);
+        bbq->setSidebandStream(stream);
     }
 }
 
@@ -147,7 +142,7 @@ BLASTBufferQueue::BLASTBufferQueue(const std::string& name, const sp<SurfaceCont
     mBufferItemConsumer = new BLASTBufferItemConsumer(mConsumer,
                                                       GraphicBuffer::USAGE_HW_COMPOSER |
                                                               GraphicBuffer::USAGE_HW_TEXTURE,
-                                                      1, false);
+                                                      1, false, this);
     static int32_t id = 0;
     mName = name + "#" + std::to_string(id);
     auto consumerName = mName + "(BLAST Consumer)" + std::to_string(id);
@@ -158,7 +153,6 @@ BLASTBufferQueue::BLASTBufferQueue(const std::string& name, const sp<SurfaceCont
     mBufferItemConsumer->setBufferFreedListener(this);
     mBufferItemConsumer->setDefaultBufferSize(mSize.width, mSize.height);
     mBufferItemConsumer->setDefaultBufferFormat(convertBufferFormat(format));
-    mBufferItemConsumer->setBlastBufferQueue(this);
 
     ComposerService::getComposerService()->getMaxAcquiredBufferCount(&mMaxAcquiredBuffers);
     mBufferItemConsumer->setMaxAcquiredBufferCount(mMaxAcquiredBuffers);
@@ -177,7 +171,6 @@ BLASTBufferQueue::BLASTBufferQueue(const std::string& name, const sp<SurfaceCont
 }
 
 BLASTBufferQueue::~BLASTBufferQueue() {
-    mBufferItemConsumer->setBlastBufferQueue(nullptr);
     if (mPendingTransactions.empty()) {
         return;
     }
diff --git a/libs/gui/include/gui/BLASTBufferQueue.h b/libs/gui/include/gui/BLASTBufferQueue.h
index 6c5b2aa53c..bc35792bef 100644
--- a/libs/gui/include/gui/BLASTBufferQueue.h
+++ b/libs/gui/include/gui/BLASTBufferQueue.h
@@ -38,11 +38,11 @@ class BufferItemConsumer;
 class BLASTBufferItemConsumer : public BufferItemConsumer {
 public:
     BLASTBufferItemConsumer(const sp<IGraphicBufferConsumer>& consumer, uint64_t consumerUsage,
-                            int bufferCount, bool controlledByApp)
+                            int bufferCount, bool controlledByApp, wp<BLASTBufferQueue> bbq)
           : BufferItemConsumer(consumer, consumerUsage, bufferCount, controlledByApp),
+            mBLASTBufferQueue(std::move(bbq)),
             mCurrentlyConnected(false),
-            mPreviouslyConnected(false),
-            mBLASTBufferQueue(nullptr) {}
+            mPreviouslyConnected(false) {}
 
     void onDisconnect() override;
     void addAndGetFrameTimestamps(const NewFrameEventsEntry* newTimestamps,
@@ -59,15 +59,15 @@ protected:
     void onSidebandStreamChanged() override REQUIRES(mMutex);
 
 private:
+    const wp<BLASTBufferQueue> mBLASTBufferQueue;
+
     uint64_t mCurrentFrameNumber = 0;
 
     Mutex mMutex;
-    std::mutex mBufferQueueMutex;
     ConsumerFrameEventHistory mFrameEventHistory GUARDED_BY(mMutex);
     std::queue<uint64_t> mDisconnectEvents GUARDED_BY(mMutex);
     bool mCurrentlyConnected GUARDED_BY(mMutex);
     bool mPreviouslyConnected GUARDED_BY(mMutex);
-    BLASTBufferQueue* mBLASTBufferQueue GUARDED_BY(mBufferQueueMutex);
 };
 
 class BLASTBufferQueue
-- 
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