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8011802: NPG: init_dependencies in class loader data graph can cause invalid CLD

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Restructure initialization of ClassLoaderData to not add a new instance if init_dependencies fail

Reviewed-by: stefank, coleenp
This commit is contained in:
Mikael Gerdin 2013-04-23 08:39:55 +02:00
parent ddbf6ad621
commit c47ec9b4ca
3 changed files with 30 additions and 24 deletions
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43
hotspot/src/share/vm/classfile/classLoaderData.cpp
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@ -53,6 +53,7 @@
#include "classfile/metadataOnStackMark.hpp"
#include "classfile/systemDictionary.hpp"
#include "code/codeCache.hpp"
#include "memory/gcLocker.hpp"
#include "memory/metadataFactory.hpp"
#include "memory/metaspaceShared.hpp"
#include "memory/oopFactory.hpp"
@ -423,7 +424,7 @@ void ClassLoaderData::free_deallocate_list() {
// These anonymous class loaders are to contain classes used for JSR292
ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
// Add a new class loader data to the graph.
return ClassLoaderDataGraph::add(NULL, loader, CHECK_NULL);
return ClassLoaderDataGraph::add(loader, true, CHECK_NULL);
}
const char* ClassLoaderData::loader_name() {
@ -495,30 +496,40 @@ ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
// Add a new class loader data node to the list. Assign the newly created
// ClassLoaderData into the java/lang/ClassLoader object as a hidden field
ClassLoaderData* ClassLoaderDataGraph::add(ClassLoaderData** cld_addr, Handle loader, TRAPS) {
ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
// Not assigned a class loader data yet.
// Create one.
ClassLoaderData* *list_head = &_head;
ClassLoaderData* next = _head;
bool is_anonymous = (cld_addr == NULL);
ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous);
cld->init_dependencies(THREAD);
if (HAS_PENDING_EXCEPTION) {
delete cld;
return NULL;
}
if (cld_addr != NULL) {
// First, Atomically set it
ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
if (old != NULL) {
delete cld;
// Returns the data.
return old;
No_Safepoint_Verifier no_safepoints; // nothing is keeping the dependencies array in cld alive
// make sure we don't encounter a GC until we've inserted
// cld into the CLDG
if (!is_anonymous) {
ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
if (cld_addr != NULL) {
// First, Atomically set it
ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
if (old != NULL) {
delete cld;
// Returns the data.
return old;
}
}
}
// We won the race, and therefore the task of adding the data to the list of
// class loader data
ClassLoaderData** list_head = &_head;
ClassLoaderData* next = _head;
do {
cld->set_next(next);
ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
@ -531,10 +542,6 @@ ClassLoaderData* ClassLoaderDataGraph::add(ClassLoaderData** cld_addr, Handle lo
cld->loader_name());
tty->print_cr("]");
}
// Create dependencies after the CLD is added to the list. Otherwise,
// the GC GC will not find the CLD and the _class_loader field will
// not be updated.
cld->init_dependencies(CHECK_NULL);
return cld;
}
next = exchanged;