[release/8.0] Fix a possible infinite wait for GC completion at process shutdown.

src/coreclr/vm/ceemain.cpp

@@ -392,6 +392,12 @@ BOOL g_singleVersionHosting;
 typedef BOOL(WINAPI* PINITIALIZECONTEXT2)(PVOID Buffer, DWORD ContextFlags, PCONTEXT* Context, PDWORD ContextLength, ULONG64 XStateCompactionMask);
 PINITIALIZECONTEXT2 g_pfnInitializeContext2 = NULL;
 
+static BOOLEAN WINAPI RtlDllShutdownInProgressFallback()
+{
+    return g_fProcessDetach;
+}
+PRTLDLLSHUTDOWNINPROGRESS g_pfnRtlDllShutdownInProgress = &RtlDllShutdownInProgressFallback;
+
 #ifdef TARGET_X86
 typedef VOID(__cdecl* PRTLRESTORECONTEXT)(PCONTEXT ContextRecord, struct _EXCEPTION_RECORD* ExceptionRecord);
 PRTLRESTORECONTEXT g_pfnRtlRestoreContext = NULL;
@@ -402,8 +408,12 @@ void InitializeOptionalWindowsAPIPointers()
     HMODULE hm = GetModuleHandleW(_T("kernel32.dll"));
     g_pfnInitializeContext2 = (PINITIALIZECONTEXT2)GetProcAddress(hm, "InitializeContext2");
 
-#ifdef TARGET_X86
     hm = GetModuleHandleW(_T("ntdll.dll"));
+    PRTLDLLSHUTDOWNINPROGRESS pfn = (PRTLDLLSHUTDOWNINPROGRESS)GetProcAddress(hm, "RtlDllShutdownInProgress");
+    if (pfn != NULL)
+        g_pfnRtlDllShutdownInProgress = pfn;
+
+#ifdef TARGET_X86
     g_pfnRtlRestoreContext = (PRTLRESTORECONTEXT)GetProcAddress(hm, "RtlRestoreContext");
 #endif //TARGET_X86
 }

src/coreclr/vm/vars.hpp

@@ -478,12 +478,24 @@ GVAL_DECL(bool, g_metadataUpdatesApplied);
 #endif
 EXTERN bool g_fManagedAttach;
 
+#ifdef HOST_WINDOWS
+typedef BOOLEAN (WINAPI* PRTLDLLSHUTDOWNINPROGRESS)();
+EXTERN PRTLDLLSHUTDOWNINPROGRESS g_pfnRtlDllShutdownInProgress;
+#endif
+
 // Indicates whether we're executing shut down as a result of DllMain
 // (DLL_PROCESS_DETACH). See comments at code:EEShutDown for details.
-inline BOOL    IsAtProcessExit()
+inline bool IsAtProcessExit()
 {
     SUPPORTS_DAC;
+#if defined(DACCESS_COMPILE) || !defined(HOST_WINDOWS)
     return g_fProcessDetach;
+#else
+    // RtlDllShutdownInProgress provides more accurate information about whether the process is shutting down.
+    // Use it if it is available to avoid shutdown deadlocks.
+    // https://learn.microsoft.com/windows/win32/devnotes/rtldllshutdowninprogress
+    return g_pfnRtlDllShutdownInProgress();
+#endif
 }
 
 enum FWStatus

src/tests/Regressions/coreclr/GitHub_107800/test107800.cs

@@ -0,0 +1,25 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+
+public class Program
+{
+    public static int Main()
+    {
+        Task.Run(() =>
+        {
+            for (; ; )
+            {
+                GC.Collect();
+            }
+        });
+
+        Thread.Sleep(10);
+        Environment.Exit(100);
+
+        throw new Exception("UNREACHABLE");
+    }
+}

src/tests/Regressions/coreclr/GitHub_107800/test107800.csproj

@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <!-- Calls ExitProcess -->
+    <RequiresProcessIsolation>true</RequiresProcessIsolation>
+    <CLRTestPriority>0</CLRTestPriority>
+    <OutputType>Exe</OutputType>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="test107800.cs" />
+  </ItemGroup>
+</Project>