src/share/vm/prims/jvmtiEnvBase.hpp

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

*** 30,39 ****
--- 30,40 ----
  #include "prims/jvmtiEventController.hpp"
  #include "prims/jvmtiThreadState.hpp"
  #include "runtime/fieldDescriptor.hpp"
  #include "runtime/frame.hpp"
  #include "runtime/handles.inline.hpp"
+ #include "runtime/orderAccess.hpp"
  #include "runtime/thread.hpp"
  #include "runtime/vm_operations.hpp"
  #include "utilities/growableArray.hpp"
  #include "utilities/macros.hpp"
  
*** 95,105 ****
    JvmtiEnvBase* _next;
    bool _is_retransformable;
    const void *_env_local_storage;     // per env agent allocated data.
    jvmtiEventCallbacks _event_callbacks;
    jvmtiExtEventCallbacks _ext_event_callbacks;
!   JvmtiTagMap* _tag_map;
    JvmtiEnvEventEnable _env_event_enable;
    jvmtiCapabilities _current_capabilities;
    jvmtiCapabilities _prohibited_capabilities;
    volatile bool _class_file_load_hook_ever_enabled;
    static volatile bool _needs_clean_up;
--- 96,106 ----
    JvmtiEnvBase* _next;
    bool _is_retransformable;
    const void *_env_local_storage;     // per env agent allocated data.
    jvmtiEventCallbacks _event_callbacks;
    jvmtiExtEventCallbacks _ext_event_callbacks;
!   JvmtiTagMap* volatile _tag_map;
    JvmtiEnvEventEnable _env_event_enable;
    jvmtiCapabilities _current_capabilities;
    jvmtiCapabilities _prohibited_capabilities;
    volatile bool _class_file_load_hook_ever_enabled;
    static volatile bool _needs_clean_up;
*** 249,258 ****
--- 250,266 ----
  
    JvmtiTagMap* tag_map() {
      return _tag_map;
    }
  
+   JvmtiTagMap* acquire_tag_map() {
+     return (JvmtiTagMap*)OrderAccess::load_ptr_acquire(&_tag_map);
+   }
+ 
+   void release_set_tag_map(JvmtiTagMap* tag_map) {
+     OrderAccess::release_store_ptr(&_tag_map, tag_map);
+   }
  
    // return true if event is enabled globally or for any thread
    // True only if there is a callback for it.
    bool is_enabled(jvmtiEvent event_type) {
      return _env_event_enable.is_enabled(event_type);