8334769: Shenandoah: Move CodeCache_lock close to its use in ShenandoahConcurrentNMethodIterator

Reviewed-by: phh
Backport-of: 4ebb77120af5a4ccbfde63b24cb50e05a3161f16

src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.cpp

 /*
- * Copyright (c) 2017, 2021, Red Hat, Inc. All rights reserved.
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2017, 2022, Red Hat, Inc. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -163,12 +164,10 @@ public:
     AbstractGangTask("Shenandoah Disarm NMethods"),
     _iterator(ShenandoahCodeRoots::table()) {
     assert(SafepointSynchronize::is_at_safepoint(), "Only at a safepoint");
-    MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
     _iterator.nmethods_do_begin();
   }
 
   ~ShenandoahDisarmNMethodsTask() {
-    MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
     _iterator.nmethods_do_end();
   }
 
@@ -270,12 +269,10 @@ public:
     _cl(unloading_occurred),
     _verifier(verifier),
     _iterator(ShenandoahCodeRoots::table()) {
-    MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
     _iterator.nmethods_do_begin();
   }
 
   ~ShenandoahUnlinkTask() {
-    MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
     _iterator.nmethods_do_end();
   }
 
@@ -330,12 +327,10 @@ public:
     AbstractGangTask("Shenandoah Purge NMethods"),
     _cl(),
     _iterator(ShenandoahCodeRoots::table()) {
-    MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
     _iterator.nmethods_do_begin();
   }
 
   ~ShenandoahNMethodPurgeTask() {
-    MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
     _iterator.nmethods_do_end();
   }
 

src/hotspot/share/gc/shenandoah/shenandoahConcurrentGC.cpp

 /*
- * Copyright (c) 2021, Red Hat, Inc. All rights reserved.
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2022, Red Hat, Inc. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -750,14 +751,12 @@ public:
     _nmethod_itr(ShenandoahCodeRoots::table()),
     _phase(phase) {
     if (ShenandoahHeap::heap()->unload_classes()) {
-      MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
       _nmethod_itr.nmethods_do_begin();
     }
   }
 
   ~ShenandoahConcurrentWeakRootsEvacUpdateTask() {
     if (ShenandoahHeap::heap()->unload_classes()) {
-      MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
       _nmethod_itr.nmethods_do_end();
     }
     // Notify runtime data structures of potentially dead oops
@@ -862,14 +861,12 @@ public:
     _cld_roots(phase, ShenandoahHeap::heap()->workers()->active_workers()),
     _nmethod_itr(ShenandoahCodeRoots::table()) {
     if (!ShenandoahHeap::heap()->unload_classes()) {
-      MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
       _nmethod_itr.nmethods_do_begin();
     }
   }
 
   ~ShenandoahConcurrentRootsEvacUpdateTask() {
     if (!ShenandoahHeap::heap()->unload_classes()) {
-      MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
       _nmethod_itr.nmethods_do_end();
     }
   }

src/hotspot/share/gc/shenandoah/shenandoahNMethod.cpp

 /*
- * Copyright (c) 2019, 2021, Red Hat, Inc. All rights reserved.
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2022, Red Hat, Inc. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -546,7 +547,7 @@ ShenandoahConcurrentNMethodIterator::ShenandoahConcurrentNMethodIterator(Shenand
 }
 
 void ShenandoahConcurrentNMethodIterator::nmethods_do_begin() {
-  assert(CodeCache_lock->owned_by_self(), "Lock must be held");
+  MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
   _table_snapshot = _table->snapshot_for_iteration();
 }
 
@@ -556,7 +557,7 @@ void ShenandoahConcurrentNMethodIterator::nmethods_do(NMethodClosure* cl) {
 }
 
 void ShenandoahConcurrentNMethodIterator::nmethods_do_end() {
-  assert(CodeCache_lock->owned_by_self(), "Lock must be held");
+  MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
   _table->finish_iteration(_table_snapshot);
   CodeCache_lock->notify_all();
 }