Fix for post_vthread_unmount

Author: pchilano

src/hotspot/share/prims/jvmtiExport.cpp

@@ -1670,17 +1670,17 @@ void JvmtiExport::post_vthread_mount(jobject vthread) {
   }
 }
 
-void JvmtiExport::post_vthread_unmount(jobject vthread) {
+void JvmtiExport::post_vthread_unmount(jobject vthread, JvmtiThreadState* state_to_use) {
   if (JvmtiEnv::get_phase() < JVMTI_PHASE_PRIMORDIAL) {
     return;
   }
   JavaThread *thread = JavaThread::current();
   HandleMark hm(thread);
   EVT_TRIG_TRACE(EXT_EVENT_VIRTUAL_THREAD_UNMOUNT, ("[%p] Trg Virtual Thread Unmount event triggered", vthread));
 
-  // On preemption JVMTI state rebinding has already happened so get it always directly from the oop.
-  JvmtiThreadState *state = java_lang_Thread::jvmti_thread_state(JNIHandles::resolve(vthread));
-  if (state == NULL) {
+  // On preemption, JVMTI state rebinding has already happened so we use the passed one.
+  JvmtiThreadState *state = state_to_use == nullptr ? get_jvmti_thread_state(thread) : state_to_use;
+  if (state == nullptr) {
     return;
   }
 

src/hotspot/share/prims/jvmtiExport.hpp

@@ -358,7 +358,7 @@ class JvmtiExport : public AllStatic {
   static void post_vthread_start         (jthread vthread) NOT_JVMTI_RETURN;
   static void post_vthread_end           (jthread vthread) NOT_JVMTI_RETURN;
   static void post_vthread_mount         (jthread vthread) NOT_JVMTI_RETURN;
-  static void post_vthread_unmount       (jthread vthread) NOT_JVMTI_RETURN;
+  static void post_vthread_unmount       (jthread vthread, JvmtiThreadState* state_to_use = nullptr) NOT_JVMTI_RETURN;
 
   static void continuation_yield_cleanup (JavaThread* thread, jint continuation_frame_count) NOT_JVMTI_RETURN;
 

src/hotspot/share/prims/jvmtiThreadState.cpp

@@ -667,7 +667,10 @@ JvmtiVTMSTransitionDisabler::VTMS_unmount_end(jobject vthread) {
 
   if (thread->pending_jvmti_unmount_event()) {
     assert(java_lang_VirtualThread::is_preempted(JNIHandles::resolve(vthread)), "should be marked preempted");
-    JvmtiExport::post_vthread_unmount(vthread);
+    // State rebinding has already happened so use the correct state when posting the event.
+    Handle vth = Handle(thread, JNIHandles::resolve_external_guard(vthread));
+    JvmtiThreadState* state = JvmtiThreadState::state_for(nullptr, vth);
+    JvmtiExport::post_vthread_unmount(vthread, state);
     thread->set_pending_jvmti_unmount_event(false);
   }
 }