--- a/hotspot/src/share/vm/runtime/thread.cpp	Wed Feb 01 07:59:01 2012 -0800
+++ b/hotspot/src/share/vm/runtime/thread.cpp	Wed Feb 01 16:57:08 2012 -0800
@@ -33,6 +33,7 @@
 #include "interpreter/linkResolver.hpp"
 #include "interpreter/oopMapCache.hpp"
 #include "jvmtifiles/jvmtiEnv.hpp"
+#include "memory/gcLocker.inline.hpp"
 #include "memory/oopFactory.hpp"
 #include "memory/universe.inline.hpp"
 #include "oops/instanceKlass.hpp"
@@ -2278,6 +2279,26 @@
   }
 }
 
+// This is a variant of the normal
+// check_special_condition_for_native_trans with slightly different
+// semantics for use by critical native wrappers.  It does all the
+// normal checks but also performs the transition back into
+// thread_in_Java state.  This is required so that critical natives
+// can potentially block and perform a GC if they are the last thread
+// exiting the GC_locker.
+void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
+  check_special_condition_for_native_trans(thread);
+
+  // Finish the transition
+  thread->set_thread_state(_thread_in_Java);
+
+  if (thread->do_critical_native_unlock()) {
+    ThreadInVMfromJavaNoAsyncException tiv(thread);
+    GC_locker::unlock_critical(thread);
+    thread->clear_critical_native_unlock();
+  }
+}
+
 // We need to guarantee the Threads_lock here, since resumes are not
 // allowed during safepoint synchronization
 // Can only resume from an external suspension