1 /*
   2  * Copyright (c) 2002, 2010, 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 "gc_implementation/concurrentMarkSweep/cmsLockVerifier.hpp"
  27 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
  28 #include "runtime/vmThread.hpp"
  29 
  30 ///////////// Locking verification specific to CMS //////////////
  31 // Much like "assert_lock_strong()", except that it relaxes the
  32 // assertion somewhat for the parallel GC case, where VM thread
  33 // or the CMS thread might hold the lock on behalf of the parallel
  34 // threads. The second argument is in support of an extra locking
  35 // check for CFL spaces' free list locks.
  36 #ifndef PRODUCT
  37 void CMSLockVerifier::assert_locked(const Mutex* lock,
  38                                     const Mutex* p_lock1,
  39                                     const Mutex* p_lock2) {
  40   if (!Universe::is_fully_initialized()) {
  41     return;
  42   }
  43 
  44   Thread* myThread = Thread::current();
  45 
  46   if (lock == NULL) { // a "lock-free" structure, e.g. MUT, protected by CMS token
  47     assert(p_lock1 == NULL && p_lock2 == NULL, "Unexpected caller error");
  48     if (myThread->is_ConcurrentGC_thread()) {
  49       // This test might have to change in the future, if there can be
  50       // multiple peer CMS threads.  But for now, if we're testing the CMS
  51       assert(myThread == ConcurrentMarkSweepThread::cmst(),
  52              "In CMS, CMS thread is the only Conc GC thread.");
  53       assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(),
  54              "CMS thread should have CMS token");
  55     } else if (myThread->is_VM_thread()) {
  56       assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(),
  57              "VM thread should have CMS token");
  58     } else {
  59       // Token should be held on our behalf by one of the other
  60       // of CMS or VM thread; not enough easily testable
  61       // state info to test which here.
  62       assert(myThread->is_GC_task_thread(), "Unexpected thread type");
  63     }
  64     return;
  65   }
  66 
  67   if (myThread->is_VM_thread()
  68       || myThread->is_ConcurrentGC_thread()
  69       || myThread->is_Java_thread()) {
  70     // Make sure that we are holding the associated lock.
  71     assert_lock_strong(lock);
  72     // The checking of p_lock is a spl case for CFLS' free list
  73     // locks: we make sure that none of the parallel GC work gang
  74     // threads are holding "sub-locks" of freeListLock(). We check only
  75     // the parDictionaryAllocLock because the others are too numerous.
  76     // This spl case code is somewhat ugly and any improvements
  77     // are welcome.
  78     assert(p_lock1 == NULL || !p_lock1->is_locked() || p_lock1->owned_by_self(),
  79            "Possible race between this and parallel GC threads");
  80     assert(p_lock2 == NULL || !p_lock2->is_locked() || p_lock2->owned_by_self(),
  81            "Possible race between this and parallel GC threads");
  82   } else if (myThread->is_GC_task_thread()) {
  83     // Make sure that the VM or CMS thread holds lock on our behalf
  84     // XXX If there were a concept of a gang_master for a (set of)
  85     // gang_workers, we could have used the identity of that thread
  86     // for checking ownership here; for now we just disjunct.
  87     assert(lock->owner() == VMThread::vm_thread() ||
  88            lock->owner() == ConcurrentMarkSweepThread::cmst(),
  89            "Should be locked by VM thread or CMS thread on my behalf");
  90     if (p_lock1 != NULL) {
  91       assert_lock_strong(p_lock1);
  92     }
  93     if (p_lock2 != NULL) {
  94       assert_lock_strong(p_lock2);
  95     }
  96   } else {
  97     // Make sure we didn't miss some other thread type calling into here;
  98     // perhaps as a result of future VM evolution.
  99     ShouldNotReachHere();
 100   }
 101 }
 102 #endif