text: // Tests that doing dfsan_flush() while another thread is executing doesn't
  // segfault.
  // RUN: %clang_dfsan %s -o %t && %run %t
  #include <assert.h>
  #include <pthread.h>
  #include <sanitizer/dfsan_interface.h>
  #include <stdlib.h>
  
  static unsigned char GlobalBuf[4096];
  static int ShutDownThread;
  static int StartFlush;
  
  // Access GlobalBuf continuously, causing its shadow to be touched as well.
  // When main() calls dfsan_flush(), no segfault should be triggered.
  static void *accessGlobalInBackground(void *Arg) {
    __atomic_store_n(&StartFlush, 1, __ATOMIC_RELEASE);
  
    while (!__atomic_load_n(&ShutDownThread, __ATOMIC_ACQUIRE))
      for (unsigned I = 0; I < sizeof(GlobalBuf); ++I)
        ++GlobalBuf[I];
  
    return NULL;
  }
  
  int main() {
    pthread_t Thread;
    pthread_create(&Thread, NULL, accessGlobalInBackground, NULL);
    while (!__atomic_load_n(&StartFlush, __ATOMIC_ACQUIRE))
      ; // Spin
  
    dfsan_flush();
  
    __atomic_store_n(&ShutDownThread, 1, __ATOMIC_RELEASE);
    pthread_join(Thread, NULL);
    return 0;
  }
  