Change g_fEEShutDown to be Volatile #116885
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g_fEEShutDown is read without locks. Make it volatile to ensure that the up-to-date value is read with Arm64 weak memory model. Cleanup g_fEEShutDown flags Fixes dotnet#106242
jkotas
commented
Jun 20, 2025
| @@ -90,12 +90,8 @@ | |||
| #include <minipal/mutex.h> | |||
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| #define ShutDown_Start 0x00000001 | |||
| #define ShutDown_Finalize1 0x00000002 | |||
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Debug-only bit, only used for low-value assert
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Tagging subscribers to this area: @mangod9 |
jkotas
commented
Jun 20, 2025
| #define ShutDown_Finalize2 0x00000004 | ||
| #define ShutDown_Profiler 0x00000008 | ||
| #define ShutDown_COM 0x00000010 | ||
| #define ShutDown_SyncBlock 0x00000020 | ||
| #define ShutDown_IUnknown 0x00000040 |
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Unused or low-value debug-only bits
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Pull Request Overview
This PR makes g_fEEShutDown a volatile variable for correct ordering on weak-memory models and cleans up obsolete shutdown flag usage throughout the VM.
- Mark
g_fEEShutDownasVolatile<DWORD>(except in DACCESS builds) and update its implementation. - Remove deprecated shutdown mask constants and their associated bitwise logic.
- Simplify and update conditional checks and cleanup logic that depended on the old flags.
Reviewed Changes
Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
| src/coreclr/vm/vars.hpp | Switched g_fEEShutDown to Volatile<DWORD> and removed profiling vars. |
| src/coreclr/vm/vars.cpp | Updated GVAL_IMPL for g_fEEShutDown to use the volatile type. |
| src/coreclr/vm/threads.cpp | Removed legacy if (g_fEEShutDown == 0) guard around thread termination. |
| src/coreclr/vm/runtimecallablewrapper.cpp | Simplified PRECONDITION to drop shutdown-based branch. |
| src/coreclr/vm/interoputil.cpp | Removed shutdown-specific sync block cleanup in CleanupSyncBlockComData. |
| src/coreclr/vm/crst.h | Dropped obsolete ShutDown_* mask definitions. |
| src/coreclr/vm/ceemain.cpp | Cleared out assignments to removed shutdown flags. |
| src/coreclr/vm/appdomain.cpp | Updated assertion to use boolean g_fEEShutDown instead of a mask. |
| src/coreclr/inc/dacvars.h | Changed DACVAR definition to DEFINE_DACVAR_VOLATILE for shutdown flag. |
Comments suppressed due to low confidence (2)
src/coreclr/vm/threads.cpp:868
- The original
if (g_fEEShutDown == 0)guard was removed, soOnThreadTerminatenow runs unconditionally even during shutdown. This changes shutdown semantics and may invoke CLR state incorrectly; consider restoring a volatile-based check to gate termination calls.
th->SetThreadState(Thread::TS_ReportDead);
src/coreclr/vm/interoputil.cpp:1202
- The shutdown-specific call to
MinorCleanupSyncBlockComDatawas removed, so COM SyncBlock data may no longer be cleaned up during shutdown. If this cleanup is still required at process exit, reintroduce the appropriate volatile-check logic.
void CleanupSyncBlockComData(InteropSyncBlockInfo* pInteropInfo)
jkotas
commented
Jun 20, 2025
| @@ -1209,9 +1209,6 @@ void CleanupSyncBlockComData(InteropSyncBlockInfo* pInteropInfo) | |||
| } | |||
| CONTRACTL_END; | |||
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| if ((g_fEEShutDown & ShutDown_SyncBlock) && IsAtProcessExit() ) | |||
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ShutDown_SyncBlock was never set in release build, so this condition was always false in the shipping bits. Better to align non-release builds to do the same
jkotas
commented
Jun 20, 2025
| @@ -865,11 +865,8 @@ void DestroyThread(Thread *th) | |||
| th->UnmarkThreadForAbort(); | |||
| } | |||
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| if (g_fEEShutDown == 0) | |||
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Unnecessary check (also, the way it is written triggered a build error after changing g_fEEShutDown to Volatile)
jkotas
commented
Jun 20, 2025
| @@ -151,9 +151,6 @@ GVAL_IMPL_INIT(DWORD, g_externalMethodFixupTraceActiveCount, 0); | |||
| #endif // DEBUGGING_SUPPORTED | |||
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| #if defined(PROFILING_SUPPORTED_DATA) || defined(PROFILING_SUPPPORTED) | |||
| // Profiling support | |||
| HINSTANCE g_pDebuggerDll = NULL; | |||
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Dead code that I happen to notice
jkotas
commented
Jun 20, 2025
| GVAL_DECL(DWORD, g_fEEShutDown); | ||
| #else | ||
| GVAL_DECL(Volatile<DWORD>, g_fEEShutDown); |
jkotas
changed the title
mangod9
reviewed
Jun 21, 2025
mangod9
reviewed
Jun 21, 2025
jkoritzinsky
approved these changes
Jun 21, 2025
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g_fEEShutDown is read without locks. Make it volatile to ensure that the up-to-date value is read with Arm64 weak memory model.
Cleanup g_fEEShutDown flags
Fixes #106242