jdk8-mips64-public/hotspot: src/share/vm/classfile/metadataOnStackMark.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) 2013, 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/metadataOnStackMark.hpp"

    27 #include "code/codeCache.hpp"

    28 #include "compiler/compileBroker.hpp"

    29 #include "oops/metadata.hpp"

    30 #include "runtime/synchronizer.hpp"

    31 #include "runtime/thread.hpp"

    32 #include "utilities/growableArray.hpp"

    35 // Keep track of marked on-stack metadata so it can be cleared.

    36 GrowableArray<Metadata*>* _marked_objects = NULL;

    37 NOT_PRODUCT(bool MetadataOnStackMark::_is_active = false;)

    39 // Walk metadata on the stack and mark it so that redefinition doesn't delete

    40 // it.  Class unloading also walks the previous versions and might try to

    41 // delete it, so this class is used by class unloading also.

    42 MetadataOnStackMark::MetadataOnStackMark() {

    43   assert(SafepointSynchronize::is_at_safepoint(), "sanity check");

    44   NOT_PRODUCT(_is_active = true;)

    45   if (_marked_objects == NULL) {

    46     _marked_objects = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(1000, true);

    47   }

    48   Threads::metadata_do(Metadata::mark_on_stack);

    49   CodeCache::alive_nmethods_do(nmethod::mark_on_stack);

    50   CompileBroker::mark_on_stack();

    51 }

    53 MetadataOnStackMark::~MetadataOnStackMark() {

    54   assert(SafepointSynchronize::is_at_safepoint(), "sanity check");

    55   // Unmark everything that was marked.   Can't do the same walk because

    56   // redefine classes messes up the code cache so the set of methods

    57   // might not be the same.

    58   for (int i = 0; i< _marked_objects->length(); i++) {

    59     _marked_objects->at(i)->set_on_stack(false);

    60   }

    61   _marked_objects->clear();   // reuse growable array for next time.

    62   NOT_PRODUCT(_is_active = false;)

    63 }

    65 // Record which objects are marked so we can unmark the same objects.

    66 void MetadataOnStackMark::record(Metadata* m) {

    67   assert(_is_active, "metadata on stack marking is active");

    68   _marked_objects->push(m);

    69 }

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

src/share/vm/classfile/metadataOnStackMark.cpp@2c022e432e10

src/share/vm/classfile/metadataOnStackMark.cpp