rev 49672 : 8200374: Add ThreadsSMRSupport::verify_hazard_pointer_scanned() to verify threads_do().
rev 49673 : Add missing NULL check; use proper lock-free get/set with TracingExport::_sampler_thread.
rev 49674 : Rename TracingExport::get_sampler_thread() to TracingExport::sampler_thread_acquire() and TracingExport::set_sampler_thread() to TracingExport::set_sampler_thread_with_lock(); set_sampler_thread_with_lock() uses Threads_lock toavoid conflicts with Thread-SMR scans.
rev 49675 : TracingExport::set_sampler_thread_with_lock() needs to verify assumptions and to use release_store().

   1 /*
   2  * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "runtime/orderAccess.inline.hpp"
  27 #include "trace/tracingExport.hpp"
  28 
  29 // Allow lock-free reads of _sampler_thread.
  30 Thread* volatile TracingExport::_sampler_thread = NULL;
  31 
  32 Thread* TracingExport::sampler_thread_acquire() {
  33   return (Thread*)OrderAccess::load_acquire(&_sampler_thread);
  34 }
  35 
  36 void TracingExport::set_sampler_thread_with_lock(Thread* thread) {
  37   // Grab Threads_lock to avoid conflicts with Thread-SMR scans.
  38   MutexLocker ml(Threads_lock);
  39   _sampler_thread = thread;


  40 }
--- EOF ---