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avoid calling ZALLOC after NEWOBJ_OF for RClass: need to return RClass not promoted

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This commit is contained in:
Satoshi Tagomori 2025-05-02 11:30:24 +09:00
parent 4b33b468ac
commit f24ba27d6d
3 changed files with 35 additions and 15 deletions
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30
class.c
View File

@ -1122,6 +1122,19 @@ class_alloc(VALUE flags, VALUE klass)
const rb_namespace_t *ns = rb_definition_namespace();
size_t alloc_size = sizeof(struct RClass) + sizeof(rb_classext_t);
// class_alloc is supposed to return a new object that is not promoted yet.
// So, we need to avoid GC after NEWOBJ_OF.
// To achieve that, we allocate subclass lists before NEWOBJ_OF.
//
// TODO: Note that this could cause memory leak.
// If NEWOBJ_OF fails with out of memory, these buffers will leak.
ns_subclasses = ZALLOC(rb_ns_subclasses_t);
ns_subclasses->refcount = 1;
ns_subclasses->tbl = st_init_numtable();
anchor = ZALLOC(rb_subclass_anchor_t);
anchor->ns_subclasses = ns_subclasses;
anchor->head = ZALLOC(rb_subclass_entry_t);
flags &= T_MASK;
if (RGENGC_WB_PROTECTED_CLASS) flags |= FL_WB_PROTECTED;
NEWOBJ_OF(obj, struct RClass, klass, flags, alloc_size, 0);
@ -1136,21 +1149,14 @@ class_alloc(VALUE flags, VALUE klass)
*/
RCLASS_PRIME_NS((VALUE)obj) = ns;
// Classes/Modules defined in main/local namespaces are
// writable directly.
// Classes/Modules defined in user namespaces are
// writable directly because it exists only in a namespace.
RCLASS_SET_PRIME_CLASSEXT_READWRITE((VALUE)obj, true, NAMESPACE_USER_P(ns) ? true : false);
RCLASS_SET_ORIGIN((VALUE)obj, (VALUE)obj);
RCLASS_SET_REFINED_CLASS((VALUE)obj, Qnil);
RCLASS_SET_ALLOCATOR((VALUE)obj, 0);
// ns_subclasses = IMEMO_NEW(rb_ns_subclasses_t, imemo_ns_subclasses, klass);
ns_subclasses = ZALLOC(rb_ns_subclasses_t);
ns_subclasses->refcount = 1;
ns_subclasses->tbl = st_init_numtable();
anchor = ZALLOC(rb_subclass_anchor_t);
anchor->ns_subclasses = ns_subclasses;
anchor->head = ZALLOC(rb_subclass_entry_t);
RCLASS_SET_SUBCLASSES((VALUE)obj, anchor);
return (VALUE)obj;
@ -1187,7 +1193,7 @@ class_initialize_method_table(VALUE c)
static void
class_clear_method_table(VALUE c)
{
RCLASS_WRITE_M_TBL(c, rb_id_table_create(0));
RCLASS_WRITE_M_TBL_EVEN_WHEN_PROMOTED(c, rb_id_table_create(0));
}
/**
@ -1409,7 +1415,7 @@ copy_tables(VALUE clone, VALUE orig)
RCLASS_WRITE_CVC_TBL(clone, rb_cvc_tbl_dup);
}
rb_id_table_free(RCLASS_M_TBL(clone));
RCLASS_WRITE_M_TBL(clone, 0);
RCLASS_WRITE_M_TBL_EVEN_WHEN_PROMOTED(clone, 0);
if (!RB_TYPE_P(clone, T_ICLASS)) {
st_data_t id;
@ -2400,7 +2406,7 @@ rb_prepend_module(VALUE klass, VALUE module)
if (klass_had_no_origin && klass_origin_m_tbl == RCLASS_M_TBL(subclass)) {
// backfill an origin iclass to handle refinements and future prepends
rb_id_table_foreach(RCLASS_M_TBL(subclass), clear_module_cache_i, (void *)subclass);
RCLASS_WRITE_M_TBL(subclass, klass_m_tbl);
RCLASS_WRITE_M_TBL_EVEN_WHEN_PROMOTED(subclass, klass_m_tbl);
VALUE origin = rb_include_class_new(klass_origin, RCLASS_SUPER(subclass));
rb_class_set_super(subclass, origin);
RCLASS_SET_INCLUDER(origin, RCLASS_INCLUDER(subclass));

12
internal/class.h
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@ -257,7 +257,8 @@ static inline void RCLASS_SET_FIELDS_HASH(VALUE obj, const st_table *table);
static inline void RCLASS_WRITE_FIELDS_HASH(VALUE obj, const st_table *table);
static inline uint32_t RCLASS_FIELDS_COUNT(VALUE obj);
static inline void RCLASS_SET_M_TBL(VALUE klass, struct rb_id_table *table);
static inline void RCLASS_WRITE_M_TBL(VALUE klass, struct rb_id_table *table);
// TODO: rename RCLASS_WRITE_M_TBL_WORKAROUND to RCLASS_WRITE_M_TBL with write barrier
static inline void RCLASS_WRITE_M_TBL_WORKAROUND(VALUE klass, struct rb_id_table *table, bool check_promoted);
static inline void RCLASS_SET_CONST_TBL(VALUE klass, struct rb_id_table *table, bool shared);
static inline void RCLASS_WRITE_CONST_TBL(VALUE klass, struct rb_id_table *table, bool shared);
static inline void RCLASS_WRITE_CALLABLE_M_TBL(VALUE klass, struct rb_id_table *table);
@ -568,10 +569,15 @@ RCLASS_SET_M_TBL(VALUE klass, struct rb_id_table *table)
RCLASSEXT_M_TBL(RCLASS_EXT(klass)) = table;
}
#define RCLASS_WRITE_M_TBL_EVEN_WHEN_PROMOTED(klass, table) RCLASS_WRITE_M_TBL_WORKAROUND(klass, table, false)
#define RCLASS_WRITE_M_TBL(klass, table) RCLASS_WRITE_M_TBL_WORKAROUND(klass, table, true)
static inline void
RCLASS_WRITE_M_TBL(VALUE klass, struct rb_id_table *table)
RCLASS_WRITE_M_TBL_WORKAROUND(VALUE klass, struct rb_id_table *table, bool check_promoted)
{
RUBY_ASSERT(!RB_OBJ_PROMOTED(klass));
RUBY_ASSERT(!check_promoted || !RB_OBJ_PROMOTED(klass));
// TODO: add write barrier here to guard assigning m_tbl
// see commit 28a6e4ea9d9379a654a8f7c4b37fa33aa3ccd0b7
RCLASSEXT_M_TBL(RCLASS_EXT_WRITABLE(klass)) = table;
}

8
test/ruby/test_class.rb
View File

@ -841,4 +841,12 @@ CODE
klass.define_method(:bar) {}
assert_equal klass, klass.remove_method(:bar), '[Bug #19164]'
end
def test_method_table_assignment_just_after_class_init
assert_normal_exit "#{<<~"begin;"}\n#{<<~'end;'}", 'm_tbl assignment should be done only when Class object is not promoted'
begin;
GC.stress = true
class C; end
end;
end
end