Mercurial > hg > truffle
view src/share/vm/memory/metablock.cpp @ 12301:2c022e432e10
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
author | stefank |
---|---|
date | Fri, 20 Sep 2013 10:53:28 +0200 |
parents | 335b388c4b28 |
children |
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/* * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "precompiled.hpp" #include "memory/allocation.hpp" #include "memory/metablock.hpp" #include "utilities/copy.hpp" #include "utilities/debug.hpp" // Blocks of space for metadata are allocated out of Metachunks. // // Metachunk are allocated out of MetadataVirtualspaces and once // allocated there is no explicit link between a Metachunk and // the MetadataVirtualspaces from which it was allocated. // // Each SpaceManager maintains a // list of the chunks it is using and the current chunk. The current // chunk is the chunk from which allocations are done. Space freed in // a chunk is placed on the free list of blocks (BlockFreelist) and // reused from there. // // Future modification // // The Metachunk can conceivable be replaced by the Chunk in // allocation.hpp. Note that the latter Chunk is the space for // allocation (allocations from the chunk are out of the space in // the Chunk after the header for the Chunk) where as Metachunks // point to space in a VirtualSpace. To replace Metachunks with // Chunks, change Chunks so that they can be allocated out of a VirtualSpace. size_t Metablock::_min_block_byte_size = sizeof(Metablock); // New blocks returned by the Metaspace are zero initialized. // We should fix the constructors to not assume this instead. Metablock* Metablock::initialize(MetaWord* p, size_t word_size) { if (p == NULL) { return NULL; } Metablock* result = (Metablock*) p; // Clear the memory Copy::fill_to_aligned_words((HeapWord*)result, word_size); #ifdef ASSERT result->set_word_size(word_size); #endif return result; }