remove useless codes and refactor the testcase

src/hotspot/share/prims/jvmtiExport.cpp

@@ -1090,9 +1090,7 @@ bool JvmtiExport::post_class_file_load_hook(Symbol* h_name,
   if (JvmtiEnv::get_phase() < JVMTI_PHASE_PRIMORDIAL) {
     return false;
   }
-  if (JavaThread::current()->is_in_tmp_VTMS_transition()) {
-    return false; // skip CFLH events in tmp VTMS transition
-  }
+
   if (JavaThread::current()->is_in_any_VTMS_transition()) {
     return false; // no events should be posted if thread is in any VTMS transition
   }

test/hotspot/jtreg/serviceability/jvmti/vthread/TestPinCaseWithCFLH/TestPinCaseWithCFLH.java

@@ -31,12 +31,13 @@
  * @build TestPinCaseWithCFLH
  * @run driver jdk.test.lib.util.JavaAgentBuilder
  *      TestPinCaseWithCFLH TestPinCaseWithCFLH.jar
- * @run main/othervm/timeout=100  -Djdk.virtualThreadScheduler.maxPoolSize=1 -Djdk.tracePinnedThreads=full -javaagent:TestPinCaseWithCFLH.jar TestPinCaseWithCFLH
+ * @run main/othervm/timeout=100  -Djdk.virtualThreadScheduler.maxPoolSize=1 -Djdk.tracePinnedThreads=full --enable-native-access=ALL-UNNAMED -javaagent:TestPinCaseWithCFLH.jar TestPinCaseWithCFLH
  */
 import java.lang.instrument.ClassFileTransformer;
 import java.lang.instrument.IllegalClassFormatException;
 import java.lang.instrument.Instrumentation;
 import java.security.ProtectionDomain;
+import jdk.test.lib.thread.VThreadPinner;
 
 public class TestPinCaseWithCFLH {
 
@@ -55,25 +56,15 @@ public static void premain(String agentArgs, Instrumentation instrumentation) th
 
     public static void main(String[] args) throws Exception{
         Thread t1 = Thread.ofVirtual().name("vthread-1").start(() -> {
-            result = nativeFuncPin(1);
+            VThreadPinner.runPinned(() -> {
+                try {
+                    Thread.sleep(500); // try yield, will pin, javaagent + tracePinnedThreads should not lead to crash (because of the class `PinnedThreadPrinter`)
+                } catch (Exception e) {
+                    e.printStackTrace();
+                }
+            });
         });
         t1.join();
-        assert result == 4;
     }
 
-    static int native2Java(int b) {
-        try {
-            Thread.sleep(500); // try yield, will pin, javaagent + tracePinnedThreads should not lead to crash (because of the class `PinnedThreadPrinter`)
-        } catch (Exception e) {
-            e.printStackTrace();
-        }
-
-        return b+1;
-    }
-
-    private static native int nativeFuncPin(int x);
-
-    static {
-        System.loadLibrary("TestPinCaseWithCFLH");
-    }
 }