[rtsan] Make sure rtsan gets initialized on mac

compiler-rt/lib/rtsan/rtsan.cpp

@@ -12,23 +12,42 @@
 #include <rtsan/rtsan_context.h>
 #include <rtsan/rtsan_interceptors.h>
 
+#include "sanitizer_common/sanitizer_atomic.h"
+#include "sanitizer_common/sanitizer_mutex.h"
+
 using namespace __rtsan;
+using namespace __sanitizer;
+
+static StaticSpinMutex rtsan_inited_mutex;
+static atomic_uint8_t rtsan_initialized = {0};
 
-bool __rtsan::rtsan_initialized;
-bool __rtsan::rtsan_init_is_running;
+static void SetInitialized() {
+  atomic_store(&rtsan_initialized, 1, memory_order_release);
+}
 
 extern "C" {
 
 SANITIZER_INTERFACE_ATTRIBUTE void __rtsan_init() {
-  CHECK(!rtsan_init_is_running);
-  if (rtsan_initialized)
+  CHECK(!__rtsan_is_initialized());
+  InitializeInterceptors();
+  SetInitialized();
+}
+
+SANITIZER_INTERFACE_ATTRIBUTE void __rtsan_ensure_initialized() {
+  if (LIKELY(__rtsan_is_initialized()))
     return;
-  rtsan_init_is_running = true;
 
-  InitializeInterceptors();
+  SpinMutexLock lock(&rtsan_inited_mutex);
+
+  // Someone may have initialized us while we were waiting for the lock
+  if (__rtsan_is_initialized())
+    return;
+
+  __rtsan_init();
+}
 
-  rtsan_init_is_running = false;
-  rtsan_initialized = true;
+SANITIZER_INTERFACE_ATTRIBUTE bool __rtsan_is_initialized() {
+  return atomic_load(&rtsan_initialized, memory_order_acquire) == 1;
 }
 
 SANITIZER_INTERFACE_ATTRIBUTE void __rtsan_realtime_enter() {

compiler-rt/lib/rtsan/rtsan.h

@@ -14,17 +14,17 @@
 
 extern "C" {
 
-namespace __rtsan {
-
-extern bool rtsan_initialized;
-extern bool rtsan_init_is_running;
-
-} // namespace __rtsan
-
 // Initialise rtsan interceptors.
 // A call to this method is added to the preinit array on Linux systems.
 SANITIZER_INTERFACE_ATTRIBUTE void __rtsan_init();
 
+// Initializes rtsan if it has not been initialized yet.
+// Used by the RTSan runtime to ensure that rtsan is initialized before any
+// other rtsan functions are called.
+SANITIZER_INTERFACE_ATTRIBUTE void __rtsan_ensure_initialized();
+
+SANITIZER_INTERFACE_ATTRIBUTE bool __rtsan_is_initialized();
+
 // Enter real-time context.
 // When in a real-time context, RTSan interceptors will error if realtime
 // violations are detected. Calls to this method are injected at the code

compiler-rt/lib/rtsan/rtsan_interceptors.cpp

@@ -51,16 +51,15 @@ void OSSpinLockLock(volatile OSSpinLock *__lock);
 
 using namespace __sanitizer;
 
-using __rtsan::rtsan_init_is_running;
-using __rtsan::rtsan_initialized;
-
 namespace {
 struct DlsymAlloc : public DlSymAllocator<DlsymAlloc> {
-  static bool UseImpl() { return !rtsan_initialized; }
+  static bool UseImpl() { return !__rtsan_is_initialized(); }
 };
 } // namespace
 
 void ExpectNotRealtime(const char *intercepted_function_name) {
+  __rtsan_ensure_initialized();
+
   __rtsan::GetContextForThisThread().ExpectNotRealtime(
       intercepted_function_name);
 }