GraphicsMemory fix for robustness during cleanup

Src/GraphicsMemory.cpp

@@ -96,6 +96,17 @@ namespace
             }
         }
 
+        // Explicitly destroy LinearAllocators inside a critical section
+        ~DeviceAllocator()
+        {
+            ScopedLock lock(mMutex);
+
+            for (auto& allocator : mPools)
+            {
+                allocator.reset();
+            }
+        }
+
         GraphicsResource Alloc(_In_ size_t size, _In_ size_t alignment)
         {
             ScopedLock lock(mMutex);

Src/LinearAllocator.cpp

@@ -49,7 +49,7 @@ LinearAllocatorPage::LinearAllocatorPage()
     , mGpuAddress {}
     , mOffset(0)
     , mSize(0)
-    , mRefCount(0)
+    , mRefCount(1)
 {
 }
 
@@ -64,6 +64,17 @@ size_t LinearAllocatorPage::Suballocate(_In_ size_t size, _In_ size_t alignment)
     return offset;
 }
 
+void LinearAllocatorPage::Release()
+{
+    assert(mRefCount > 0); 
+
+    if (mRefCount.fetch_sub(1) == 1)
+    {
+        mUploadResource->Unmap(0, nullptr);
+        delete this;
+    }
+}
+
 LinearAllocator::LinearAllocator(
     _In_ ID3D12Device* pDevice,
     _In_ size_t pageSize,
@@ -439,8 +450,7 @@ void LinearAllocator::FreePages( LinearAllocatorPage* page )
     {
         LinearAllocatorPage* nextPage = page->pNextPage;
 
-        page->mUploadResource->Unmap( 0, nullptr );
-        delete page;
+        page->Release();
 
         page = nextPage;
         m_totalPages--;

Src/LinearAllocator.h

@@ -64,9 +64,9 @@ namespace DirectX
         size_t BytesUsed() const { return mOffset; }
         size_t Size() const { return mSize; }
 
-        int32_t AddRef() { return mRefCount.fetch_add(1); }
-        int32_t Release() { assert(mRefCount > 0); return mRefCount.fetch_sub(1); }
+        void AddRef() { mRefCount.fetch_add(1); }
         int32_t RefCount() const { return mRefCount.load(); }
+        void Release();
 
     protected:
         friend class LinearAllocator;