src/share/vm/prims/jvmtiTagMap.cpp

rev 9028 : 8223177: Data race on JvmtiEnvBase::_tag_map in double-checked locking
Summary: Add memory fences on accesses to JvmtiEnvBase::_tag_map
Reviewed-by: dholmes, jcbeyler, sspitsyn

*** 428,438 ****
    assert(((JvmtiEnvBase *)env)->tag_map() == NULL, "tag map already exists for environment");
  
    _hashmap = new JvmtiTagHashmap();
  
    // finally add us to the environment
!   ((JvmtiEnvBase *)env)->set_tag_map(this);
  }
  
  
  // destroy a JvmtiTagMap
  JvmtiTagMap::~JvmtiTagMap() {
--- 428,438 ----
    assert(((JvmtiEnvBase *)env)->tag_map() == NULL, "tag map already exists for environment");
  
    _hashmap = new JvmtiTagHashmap();
  
    // finally add us to the environment
!   ((JvmtiEnvBase *)env)->release_set_tag_map(this);
  }
  
  
  // destroy a JvmtiTagMap
  JvmtiTagMap::~JvmtiTagMap() {
*** 497,507 ****
  }
  
  // returns the tag map for the given environments. If the tag map
  // doesn't exist then it is created.
  JvmtiTagMap* JvmtiTagMap::tag_map_for(JvmtiEnv* env) {
!   JvmtiTagMap* tag_map = ((JvmtiEnvBase*)env)->tag_map();
    if (tag_map == NULL) {
      MutexLocker mu(JvmtiThreadState_lock);
      tag_map = ((JvmtiEnvBase*)env)->tag_map();
      if (tag_map == NULL) {
        tag_map = new JvmtiTagMap(env);
--- 497,507 ----
  }
  
  // returns the tag map for the given environments. If the tag map
  // doesn't exist then it is created.
  JvmtiTagMap* JvmtiTagMap::tag_map_for(JvmtiEnv* env) {
!   JvmtiTagMap* tag_map = ((JvmtiEnvBase*)env)->acquire_tag_map();
    if (tag_map == NULL) {
      MutexLocker mu(JvmtiThreadState_lock);
      tag_map = ((JvmtiEnvBase*)env)->tag_map();
      if (tag_map == NULL) {
        tag_map = new JvmtiTagMap(env);
*** 3280,3290 ****
           SafepointSynchronize::is_at_safepoint(),
           "must be executed at a safepoint");
    if (JvmtiEnv::environments_might_exist()) {
      JvmtiEnvIterator it;
      for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
!       JvmtiTagMap* tag_map = env->tag_map();
        if (tag_map != NULL && !tag_map->is_empty()) {
          tag_map->do_weak_oops(is_alive, f);
        }
      }
    }
--- 3280,3290 ----
           SafepointSynchronize::is_at_safepoint(),
           "must be executed at a safepoint");
    if (JvmtiEnv::environments_might_exist()) {
      JvmtiEnvIterator it;
      for (JvmtiEnvBase* env = it.first(); env != NULL; env = it.next(env)) {
!       JvmtiTagMap* tag_map = env->acquire_tag_map();
        if (tag_map != NULL && !tag_map->is_empty()) {
          tag_map->do_weak_oops(is_alive, f);
        }
      }
    }