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[release/9.0] Fix init race in mono_class_try_get_[shortname]_class. #112296

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Merged
merged 1 commit into from
Feb 12, 2025
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[release/9.0] Fix init race in mono_class_try_get_[shortname]_class. #112296

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23 changes: 9 additions & 14 deletions src/mono/mono/metadata/class-internals.h
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Original file line number Diff line number Diff line change
Expand Up @@ -952,25 +952,20 @@ mono_class_get_##shortname##_class (void) \

// GENERATE_TRY_GET_CLASS_WITH_CACHE attempts mono_class_load_from_name approximately
// only once. i.e. if it fails, it will return null and not retry.
// In a race it might try a few times, but not indefinitely.
//
// FIXME This maybe has excessive volatile/barriers.
//
#define GENERATE_TRY_GET_CLASS_WITH_CACHE(shortname,name_space,name) \
MonoClass* \
mono_class_try_get_##shortname##_class (void) \
{ \
static volatile MonoClass *tmp_class; \
static volatile gboolean inited; \
MonoClass *klass = (MonoClass *)tmp_class; \
mono_memory_barrier (); \
if (!inited) { \
klass = mono_class_try_load_from_name (mono_class_generate_get_corlib_impl (), name_space, name); \
tmp_class = klass; \
mono_memory_barrier (); \
inited = TRUE; \
static MonoClass *cached_class; \
static gboolean cached_class_inited; \
gboolean tmp_inited; \
mono_atomic_load_acquire(tmp_inited, gboolean, &cached_class_inited); \
if (G_LIKELY(tmp_inited)) { \
return (MonoClass*)cached_class; \
} \
return klass; \
cached_class = mono_class_try_load_from_name (mono_class_generate_get_corlib_impl (), name_space, name); \
mono_atomic_store_release(&cached_class_inited, TRUE); \
return (MonoClass*)cached_class; \
}

GENERATE_TRY_GET_CLASS_WITH_CACHE_DECL (safehandle)
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2 changes: 2 additions & 0 deletions src/mono/mono/metadata/icall.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3391,6 +3391,8 @@ static void
init_io_stream_slots (void)
{
MonoClass* klass = mono_class_try_get_stream_class ();
g_assert(klass);

mono_class_setup_vtable (klass);
MonoMethod **klass_methods = m_class_get_methods (klass);
if (!klass_methods) {
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