1 /*
   2  * Copyright (c) 2002, 2005, 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 "incls/_precompiled.incl"
  26 # include "incls/_cmsLockVerifier.cpp.incl"
  27 
  28 ///////////// Locking verification specific to CMS //////////////
  29 // Much like "assert_lock_strong()", except that it relaxes the
  30 // assertion somewhat for the parallel GC case, where VM thread
  31 // or the CMS thread might hold the lock on behalf of the parallel
  32 // threads. The second argument is in support of an extra locking
  33 // check for CFL spaces' free list locks.
  34 #ifndef PRODUCT
  35 void CMSLockVerifier::assert_locked(const Mutex* lock,
  36                                     const Mutex* p_lock1,
  37                                     const Mutex* p_lock2) {
  38   if (!Universe::is_fully_initialized()) {
  39     return;
  40   }
  41 
  42   Thread* myThread = Thread::current();
  43 
  44   if (lock == NULL) { // a "lock-free" structure, e.g. MUT, protected by CMS token
  45     assert(p_lock1 == NULL && p_lock2 == NULL, "Unexpected caller error");
  46     if (myThread->is_ConcurrentGC_thread()) {
  47       // This test might have to change in the future, if there can be
  48       // multiple peer CMS threads.  But for now, if we're testing the CMS
  49       assert(myThread == ConcurrentMarkSweepThread::cmst(),
  50              "In CMS, CMS thread is the only Conc GC thread.");
  51       assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(),
  52              "CMS thread should have CMS token");
  53     } else if (myThread->is_VM_thread()) {
  54       assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(),
  55              "VM thread should have CMS token");
  56     } else {
  57       // Token should be held on our behalf by one of the other
  58       // of CMS or VM thread; not enough easily testable
  59       // state info to test which here.
  60       assert(myThread->is_GC_task_thread(), "Unexpected thread type");
  61     }
  62     return;
  63   }
  64 
  65   if (myThread->is_VM_thread()
  66       || myThread->is_ConcurrentGC_thread()
  67       || myThread->is_Java_thread()) {
  68     // Make sure that we are holding the associated lock.
  69     assert_lock_strong(lock);
  70     // The checking of p_lock is a spl case for CFLS' free list
  71     // locks: we make sure that none of the parallel GC work gang
  72     // threads are holding "sub-locks" of freeListLock(). We check only
  73     // the parDictionaryAllocLock because the others are too numerous.
  74     // This spl case code is somewhat ugly and any improvements
  75     // are welcome.
  76     assert(p_lock1 == NULL || !p_lock1->is_locked() || p_lock1->owned_by_self(),
  77            "Possible race between this and parallel GC threads");
  78     assert(p_lock2 == NULL || !p_lock2->is_locked() || p_lock2->owned_by_self(),
  79            "Possible race between this and parallel GC threads");
  80   } else if (myThread->is_GC_task_thread()) {
  81     // Make sure that the VM or CMS thread holds lock on our behalf
  82     // XXX If there were a concept of a gang_master for a (set of)
  83     // gang_workers, we could have used the identity of that thread
  84     // for checking ownership here; for now we just disjunct.
  85     assert(lock->owner() == VMThread::vm_thread() ||
  86            lock->owner() == ConcurrentMarkSweepThread::cmst(),
  87            "Should be locked by VM thread or CMS thread on my behalf");
  88     if (p_lock1 != NULL) {
  89       assert_lock_strong(p_lock1);
  90     }
  91     if (p_lock2 != NULL) {
  92       assert_lock_strong(p_lock2);
  93     }
  94   } else {
  95     // Make sure we didn't miss some other thread type calling into here;
  96     // perhaps as a result of future VM evolution.
  97     ShouldNotReachHere();
  98   }
  99 }
 100 #endif