jdk8-mips64-public/hotspot: src/share/vm/memory/genRemSet.cpp@2c022e432e10

8024974: Incorrect use of GC_locker::is_active()
Summary: SymbolTable and StringTable can make calls to GC_locker::is_active() outside a safepoint. This isn't safe because the GC_locker active state (lock count) is only updated at a safepoint and only remains valid as long as _needs_gc is true. However, outside a safepoint_needs_gc can change to false at any time, which makes it impossible to do a correct call to is_active() in that context. In this case these calls can just be removed since the input argument to basic_add() should never be on the heap and so there's no need to check the GC_locker state. This change also adjusts the assert() in is_active() to makes sure all calls to this function are always done under a safepoint.
Reviewed-by: brutisso, dcubed
Contributed-by: per.liden@oracle.com

     1 /*

     2  * Copyright (c) 2001, 2012, 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  */

    25 #include "precompiled.hpp"

    26 #include "classfile/classLoaderData.hpp"

    27 #include "memory/cardTableRS.hpp"

    28 #include "memory/genRemSet.hpp"

    30 // This kind of "BarrierSet" allows a "CollectedHeap" to detect and

    31 // enumerate ref fields that have been modified (since the last

    32 // enumeration.)

    34 uintx GenRemSet::max_alignment_constraint(Name nm) {

    35   switch (nm) {

    36   case GenRemSet::CardTable:

    37     return CardTableRS::ct_max_alignment_constraint();

    38   default:

    39     guarantee(false, "Unrecognized GenRemSet type.");

    40     return (0); // Make Windows compiler happy

    41   }

    42 }

    44 class HasAccumulatedModifiedOopsClosure : public KlassClosure {

    45   bool _found;

    46  public:

    47   HasAccumulatedModifiedOopsClosure() : _found(false) {}

    48   void do_klass(Klass* klass) {

    49     if (_found) {

    50       return;

    51     }

    53     if (klass->has_accumulated_modified_oops()) {

    54       _found = true;

    55     }

    56   }

    57   bool found() {

    58     return _found;

    59   }

    60 };

    62 bool KlassRemSet::mod_union_is_clear() {

    63   HasAccumulatedModifiedOopsClosure closure;

    64   ClassLoaderDataGraph::classes_do(&closure);

    66   return !closure.found();

    67 }

    70 class ClearKlassModUnionClosure : public KlassClosure {

    71  public:

    72   void do_klass(Klass* klass) {

    73     if (klass->has_accumulated_modified_oops()) {

    74       klass->clear_accumulated_modified_oops();

    75     }

    76   }

    77 };

    79 void KlassRemSet::clear_mod_union() {

    80   ClearKlassModUnionClosure closure;

    81   ClassLoaderDataGraph::classes_do(&closure);

    82 }

Mercurial > jdk8-mips64-public > hotspot / file revision

src/share/vm/memory/genRemSet.cpp@2c022e432e10

src/share/vm/memory/genRemSet.cpp