8062036: ConcurrentMarkThread::slt may be invoked before...

8062036: ConcurrentMarkThread::slt may be invoked before ConcurrentMarkThread::makeSurrogateLockerThread causing intermittent crashes
Summary: Suppress gc_alot during VM init, improve error for SLT uninitialized.
Reviewed-by: jmasa, brutisso, tschatzl

src/share/vm/gc_implementation/concurrentMarkSweep/vmCMSOperations.cpp

@@ -50,8 +50,12 @@ HS_DTRACE_PROBE_DECL(hs_private, cms__remark__end);
 void VM_CMS_Operation::acquire_pending_list_lock() {
   // The caller may block while communicating
   // with the SLT thread in order to acquire/release the PLL.
-  ConcurrentMarkSweepThread::slt()->
-    manipulatePLL(SurrogateLockerThread::acquirePLL);
+  SurrogateLockerThread* slt = ConcurrentMarkSweepThread::slt();
+  if (slt != NULL) {
+    slt->manipulatePLL(SurrogateLockerThread::acquirePLL);
+  } else {
+    SurrogateLockerThread::report_missing_slt();
+  }
 }
 
 void VM_CMS_Operation::release_and_notify_pending_list_lock() {

src/share/vm/gc_implementation/g1/vm_operations_g1.cpp

@@ -213,8 +213,12 @@ void VM_CGC_Operation::acquire_pending_list_lock() {
   assert(_needs_pll, "don't call this otherwise");
   // The caller may block while communicating
   // with the SLT thread in order to acquire/release the PLL.
-  ConcurrentMarkThread::slt()->
-    manipulatePLL(SurrogateLockerThread::acquirePLL);
+  SurrogateLockerThread* slt = ConcurrentMarkThread::slt();
+  if (slt != NULL) {
+    slt->manipulatePLL(SurrogateLockerThread::acquirePLL);
+  } else {
+    SurrogateLockerThread::report_missing_slt();
+  }
 }
 
 void VM_CGC_Operation::release_and_notify_pending_list_lock() {

src/share/vm/gc_implementation/shared/concurrentGCThread.cpp

@@ -137,6 +137,13 @@ SurrogateLockerThread* SurrogateLockerThread::make(TRAPS) {
   return res;
 }
 
+void SurrogateLockerThread::report_missing_slt() {
+  vm_exit_during_initialization(
+    "GC before GC support fully initialized: "
+    "SLT is needed but has not yet been created.");
+  ShouldNotReachHere();
+}
+
 void SurrogateLockerThread::manipulatePLL(SLT_msg_type msg) {
   MutexLockerEx x(&_monitor, Mutex::_no_safepoint_check_flag);
   assert(_buffer == empty, "Should be empty");

src/share/vm/gc_implementation/shared/concurrentGCThread.hpp

@@ -93,6 +93,9 @@ class SurrogateLockerThread: public JavaThread {
  public:
   static SurrogateLockerThread* make(TRAPS);
 
+  // Terminate VM with error message that SLT needed but not yet created.
+  static void report_missing_slt();
+
   SurrogateLockerThread();
 
   bool is_hidden_from_external_view() const     { return true; }

src/share/vm/runtime/interfaceSupport.cpp

@@ -85,7 +85,7 @@ void InterfaceSupport::gc_alot() {
   // Short-circuit any possible re-entrant gc-a-lot attempt
   if (thread->skip_gcalot()) return;
 
-  if (is_init_completed()) {
+  if (Threads::is_vm_complete()) {
 
     if (++_fullgc_alot_invocation < FullGCALotStart) {
       return;