Reset TSAN mutex state after fork

Summary:
Prevent false TSAN mutex warnings after fork().

ThreadSanitizer: double lock of a mutex (/data/users/alperyoney/fbsource/buck-out/v2/art/fbcode/a57827884e45a11c/cinderx/PythonBin/__python_3.14__/out/install/bin/python3.14+0x14f5b7) (BuildId: c5243aa7a162ca3f6d8416f73eb62bded97747ae) in pthread_mutex_lock
==================
ThreadSanitizer: reported 1 warnings
```

Reviewed By: alexmalyshev

Differential Revision: D116817969

fbshipit-source-id: dea4a4e46b3819193457d4cd5797a3a234934482

Author: yoney

cinderx/Common/define.h

@@ -10,6 +10,18 @@
 
 #include "cinderx/python.h"
 
+#if defined(__has_feature)
+#define CINDER_HAS_FEATURE(x) __has_feature(x)
+#else
+#define CINDER_HAS_FEATURE(x) 0
+#endif
+
+#if defined(__SANITIZE_THREAD__) || CINDER_HAS_FEATURE(thread_sanitizer)
+#define CINDER_TSAN_ENABLED 1
+#else
+#define CINDER_TSAN_ENABLED 0
+#endif
+
 namespace cinderx {
 
 // Whether CinderX is being built with a debug build configuration.

cinderx/Jit/codegen/tsan.h

@@ -6,18 +6,6 @@
 
 #include <cstddef>
 
-#if defined(__has_feature)
-#define CINDER_TSAN_HAS_FEATURE(x) __has_feature(x)
-#else
-#define CINDER_TSAN_HAS_FEATURE(x) 0
-#endif
-
-#if defined(__SANITIZE_THREAD__) || CINDER_TSAN_HAS_FEATURE(thread_sanitizer)
-#define CINDER_TSAN_ENABLED 1
-#else
-#define CINDER_TSAN_ENABLED 0
-#endif
-
 // JIT TSAN instrumentation is currently implemented for Linux x86-64. Other
 // platforms can still use TSAN for non-JIT code.
 #if CINDER_TSAN_ENABLED && defined(CINDER_X86_64) && defined(__linux__)

cinderx/Jit/compilation_lock.cpp

@@ -2,10 +2,35 @@
 
 #include "cinderx/Jit/compilation_lock.h"
 
+#include "cinderx/Common/define.h"
+
+#if CINDER_TSAN_ENABLED
+#include <sanitizer/tsan_interface.h>
+#endif
+
 #include <new>
 
 namespace cinderx::jit {
 
+namespace {
+
+void resetMutexAfterFork(std::recursive_mutex& mutex) {
+#if CINDER_TSAN_ENABLED
+  void* native_mutex = mutex.native_handle();
+  __tsan_mutex_pre_unlock(native_mutex, __tsan_mutex_recursive_unlock);
+  __tsan_mutex_post_unlock(native_mutex, 0);
+  __tsan_mutex_destroy(native_mutex, 0);
+#endif
+
+  new (&mutex) std::recursive_mutex{};
+
+#if CINDER_TSAN_ENABLED
+  __tsan_mutex_create(mutex.native_handle(), __tsan_mutex_write_reentrant);
+#endif
+}
+
+} // namespace
+
 std::recursive_mutex& jitCompilationMutex() {
   static std::recursive_mutex mutex;
   return mutex;
@@ -26,7 +51,7 @@ void jitCompilationAtForkChild() {
   // across the fork, so unlock() would fail with EPERM and leave the lock held
   // forever.  Destroying it isn't an option either, as it is still locked by
   // atForkPrepare(), so its lifetime ends without running its destructor.
-  new (&jitCompilationMutex()) std::recursive_mutex{};
+  resetMutexAfterFork(jitCompilationMutex());
 }
 
 } // namespace cinderx::jit