GPUUploadManager: fix render-thread deadlock when upload stream reaches max page count

Author: TheMostDiligent

Graphics/GraphicsTools/src/GPUUploadManagerImpl.cpp

@@ -1141,10 +1141,15 @@ void GPUUploadManagerImpl::ScheduleTextureUpdate(const ScheduleTextureUpdateInfo
 
 GPUUploadManagerImpl::Page* GPUUploadManagerImpl::UploadStream::CreatePage(IDeviceContext* pContext, Uint32 RequiredSize)
 {
-    const Uint32 MaxExistingPageSize = m_PageSizeToCount.empty() ? 0 : m_PageSizeToCount.rbegin()->first;
-    if (m_MaxPageCount != 0 && m_Pages.size() >= m_MaxPageCount && RequiredSize <= MaxExistingPageSize)
+    // Always create a new page from the render thread (when pContext is not null) to avoid deadlock in
+    // UploadStream::ScheduleUpdate.
+    if (pContext == nullptr)
     {
-        return nullptr;
+        const Uint32 MaxExistingPageSize = m_PageSizeToCount.empty() ? 0 : m_PageSizeToCount.rbegin()->first;
+        if (m_MaxPageCount != 0 && m_Pages.size() >= m_MaxPageCount && RequiredSize <= MaxExistingPageSize)
+        {
+            return nullptr;
+        }
     }
 
     Uint32 PageSize = m_PageSize;

Tests/DiligentCoreAPITest/src/GPUUploadManagerTest.cpp

@@ -157,7 +157,10 @@ TEST(GPUUploadManagerTest, ScheduleBufferUpdatesWithCopyBufferCallback)
     RefCntAutoPtr<IGPUUploadManager> pUploadManager;
     GPUUploadManagerCreateInfo       CreateInfo{pDevice, pContext, 1024, 2048};
     CreateInfo.InitialPageCount = 2;
-    CreateInfo.MaxPageCount     = 0;
+    // Set small max page count to test that ScheduleBufferUpdate creates new pages even when the limit
+    // is reached when called from the render thread.
+    CreateInfo.MaxPageCount      = 2;
+    CreateInfo.MaxLargePageCount = 1;
     CreateGPUUploadManager(CreateInfo, &pUploadManager);
     ASSERT_TRUE(pUploadManager != nullptr);