tsan: switch atexit mutex to the normal Mutex

[dvyukov]

Summary

Now that Mutex is blocking there is no point in using BlockingMutex.
Switch to Mutex.

Depends on D106379.

compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp

struct InterceptorContext {
   // The object is 64-byte aligned, because we want hot data to be located
   // in a single cache line if possible (it's accessed in every interceptor).
   ALIGNED(64) LibIgnore libignore;
   __sanitizer_sigaction sigactions[kSigCount];
 #if !SANITIZER_MAC && !SANITIZER_NETBSD
   unsigned finalize_key;
 #endif
 
-  BlockingMutex atexit_mu;
+  Mutex atexit_mu;
   Vector<struct AtExitCtx *> AtExitStack;
 
-  InterceptorContext()
-      : libignore(LINKER_INITIALIZED), AtExitStack() {
-  }
+  InterceptorContext() : libignore(LINKER_INITIALIZED), atexit_mu(MutexTypeAtExit), AtExitStack() {}
 };
 
 static ALIGNED(64) char interceptor_placeholder[sizeof(InterceptorContext)];
 InterceptorContext *interceptor_ctx() {
   return reinterpret_cast<InterceptorContext*>(&interceptor_placeholder[0]);
 }
 
 LibIgnore *libignore() {
TSAN_INTERCEPTOR(int, pause, int fake) {
   SCOPED_TSAN_INTERCEPTOR(pause, fake);
   return BLOCK_REAL(pause)(fake);
 }
 
 static void at_exit_wrapper() {
   AtExitCtx *ctx;
   {
     // Ensure thread-safety.
-    BlockingMutexLock l(&interceptor_ctx()->atexit_mu);
+    Lock l(&interceptor_ctx()->atexit_mu);
 
     // Pop AtExitCtx from the top of the stack of callback functions
     uptr element = interceptor_ctx()->AtExitStack.Size() - 1;
     ctx = interceptor_ctx()->AtExitStack[element];
     interceptor_ctx()->AtExitStack.PopBack();
   }
 
   Acquire(cur_thread(), (uptr)0, (uptr)ctx);
static int setup_at_exit_wrapper(ThreadState *thr, uptr pc, void(*f)(),
   // because we do not see synchronization around atexit callback list.
   ThreadIgnoreBegin(thr, pc);
   int res;
   if (!dso) {
     // NetBSD does not preserve the 2nd argument if dso is equal to 0
     // Store ctx in a local stack-like structure
 
     // Ensure thread-safety.
-    BlockingMutexLock l(&interceptor_ctx()->atexit_mu);
+    Lock l(&interceptor_ctx()->atexit_mu);
     // __cxa_atexit calls calloc. If we don't ignore interceptors, we will fail
     // due to atexit_mu held on exit from the calloc interceptor.
     ScopedIgnoreInterceptors ignore;
 
     res = REAL(__cxa_atexit)((void (*)(void *a))at_exit_wrapper, 0, 0);
     // Push AtExitCtx on the top of the stack of callback functions
     if (!res) {
       interceptor_ctx()->AtExitStack.PushBack(ctx);