1 /*

     2  * Copyright (c) 2002, 2015, 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/cms/cmsLockVerifier.hpp"

    27 #include "gc/cms/concurrentMarkSweepThread.hpp"

    28 #include "memory/universe.hpp"

    29 #include "runtime/vmThread.hpp"

    30 

    31 ///////////// Locking verification specific to CMS //////////////

    32 // Much like "assert_lock_strong()", except that it relaxes the

    33 // assertion somewhat for the parallel GC case, where VM thread

    34 // or the CMS thread might hold the lock on behalf of the parallel

    35 // threads. The second argument is in support of an extra locking

    36 // check for CFL spaces' free list locks.

    37 #ifndef PRODUCT

    38 void CMSLockVerifier::assert_locked(const Mutex* lock,

    39                                     const Mutex* p_lock1,

    40                                     const Mutex* p_lock2) {

    41   if (!Universe::is_fully_initialized()) {

    42     return;

    43   }

    44 

    45   Thread* myThread = Thread::current();

    46 

    47   if (lock == NULL) { // a "lock-free" structure, e.g. MUT, protected by CMS token

    48     assert(p_lock1 == NULL && p_lock2 == NULL, "Unexpected caller error");

    49     if (myThread->is_ConcurrentGC_thread()) {

    50       // This test might have to change in the future, if there can be

    51       // multiple peer CMS threads.  But for now, if we're testing the CMS

    52       assert(myThread == ConcurrentMarkSweepThread::cmst(),

    53              "In CMS, CMS thread is the only Conc GC thread.");

    54       assert(ConcurrentMarkSweepThread::cms_thread_has_cms_token(),

    55              "CMS thread should have CMS token");

    56     } else if (myThread->is_VM_thread()) {

    57       assert(ConcurrentMarkSweepThread::vm_thread_has_cms_token(),

    58              "VM thread should have CMS token");

    59     } else {

    60       // Token should be held on our behalf by one of the other

    61       // of CMS or VM thread; not enough easily testable

    62       // state info to test which here.

    63       assert(myThread->is_GC_task_thread(), "Unexpected thread type");

    64     }

    65     return;

    66   }

    67 

    68   if (myThread->is_VM_thread()

    69       || myThread->is_ConcurrentGC_thread()

    70       || myThread->is_Java_thread()) {

    71     // Make sure that we are holding the associated lock.

    72     assert_lock_strong(lock);

    73     // The checking of p_lock is a spl case for CFLS' free list

    74     // locks: we make sure that none of the parallel GC work gang

    75     // threads are holding "sub-locks" of freeListLock(). We check only

    76     // the parDictionaryAllocLock because the others are too numerous.

    77     // This spl case code is somewhat ugly and any improvements

    78     // are welcome.

    79     assert(p_lock1 == NULL || !p_lock1->is_locked() || p_lock1->owned_by_self(),

    80            "Possible race between this and parallel GC threads");

    81     assert(p_lock2 == NULL || !p_lock2->is_locked() || p_lock2->owned_by_self(),

    82            "Possible race between this and parallel GC threads");

    83   } else if (myThread->is_GC_task_thread()) {

    84     // Make sure that the VM or CMS thread holds lock on our behalf

    85     // XXX If there were a concept of a gang_master for a (set of)

    86     // gang_workers, we could have used the identity of that thread

    87     // for checking ownership here; for now we just disjunct.

    88     assert(lock->owner() == VMThread::vm_thread() ||

    89            lock->owner() == ConcurrentMarkSweepThread::cmst(),

    90            "Should be locked by VM thread or CMS thread on my behalf");

    91     if (p_lock1 != NULL) {

    92       assert_lock_strong(p_lock1);

    93     }

    94     if (p_lock2 != NULL) {

    95       assert_lock_strong(p_lock2);

    96     }

    97   } else {

    98     // Make sure we didn't miss some other thread type calling into here;

    99     // perhaps as a result of future VM evolution.

   100     ShouldNotReachHere();

   101   }

   102 }

   103 #endif