[llvm] r343286 - [ORC] Lock ThreadSafeContext during module destruction in ThreadSafeModule's

[Lang Hames via llvm-commits]

Author: lhames
Date: Thu Sep 27 18:41:29 2018
New Revision: 343286

URL: http://llvm.org/viewvc/llvm-project?rev=343286&view=rev
Log:
[ORC] Lock ThreadSafeContext during module destruction in ThreadSafeModule's
move constructor.

This is basically the same fix as r343261, but applied to the move constructor:
Failure to lock the context during module destruction can lead to data races if
other threads are operating on the context.

Modified:
    llvm/trunk/include/llvm/ExecutionEngine/Orc/ThreadSafeModule.h

Modified: llvm/trunk/include/llvm/ExecutionEngine/Orc/ThreadSafeModule.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ExecutionEngine/Orc/ThreadSafeModule.h?rev=343286&r1=343285&r2=343286&view=diff
==============================================================================
--- llvm/trunk/include/llvm/ExecutionEngine/Orc/ThreadSafeModule.h (original)
+++ llvm/trunk/include/llvm/ExecutionEngine/Orc/ThreadSafeModule.h Thu Sep 27 18:41:29 2018
@@ -93,6 +93,12 @@ public:
     // reverse order (i.e. module first) to ensure the dependencies are
     // protected: The old module that is being overwritten must be destroyed
     // *before* the context that it depends on.
+    // We also need to lock the context to make sure the module tear-down
+    // does not overlap any other work on the context.
+    if (M) {
+      auto L = getContextLock();
+      M = nullptr;
+    }
     M = std::move(Other.M);
     TSCtx = std::move(Other.TSCtx);
     return *this;