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gh-133467: fix data race in type_set_name #137302

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Merged
merged 4 commits into from
Aug 1, 2025
Merged

gh-133467: fix data race in type_set_name #137302

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a2776fb
fix some races
kumaraditya303 Aug 1, 2025
b124620
remove suppressions
kumaraditya303 Aug 1, 2025
dfcd1bf
decref after starting world
kumaraditya303 Aug 1, 2025
632f771
fix test
kumaraditya303 Aug 1, 2025
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14 changes: 14 additions & 0 deletions Lib/test/test_free_threading/test_type.py
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Original file line number Diff line number Diff line change
Expand Up @@ -127,6 +127,20 @@ class ClassB(Base):
obj.__class__ = ClassB


def test_name_change(self):
class Foo:
pass

def writer():
for _ in range(1000):
Foo.__name__ = 'Bar'

def reader():
for _ in range(1000):
Foo.__name__

self.run_one(writer, reader)

def run_one(self, writer_func, reader_func):
barrier = threading.Barrier(NTHREADS)

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10 changes: 8 additions & 2 deletions Objects/typeobject.c
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Expand Up @@ -1535,9 +1535,13 @@ type_set_name(PyObject *tp, PyObject *value, void *Py_UNUSED(closure))
return -1;
}

PyInterpreterState *interp = _PyInterpreterState_GET();
_PyEval_StopTheWorld(interp);
type->tp_name = tp_name;
Py_SETREF(((PyHeapTypeObject*)type)->ht_name, Py_NewRef(value));

PyObject *old_name = ((PyHeapTypeObject*)type)->ht_name;
((PyHeapTypeObject*)type)->ht_name = Py_NewRef(value);
_PyEval_StartTheWorld(interp);
Py_DECREF(old_name);
return 0;
}

Expand Down Expand Up @@ -10706,9 +10710,11 @@ slot_tp_descr_get(PyObject *self, PyObject *obj, PyObject *type)

get = _PyType_LookupRef(tp, &_Py_ID(__get__));
if (get == NULL) {
#ifndef Py_GIL_DISABLED
/* Avoid further slowdowns */
if (tp->tp_descr_get == slot_tp_descr_get)
tp->tp_descr_get = NULL;
#endif
return Py_NewRef(self);
}
if (obj == NULL)
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2 changes: 0 additions & 2 deletions Tools/tsan/suppressions_free_threading.txt
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Expand Up @@ -44,7 +44,5 @@ race:PyObject_Realloc

# gh-133467. Some of these could be hard to trigger.
race_top:_Py_slot_tp_getattr_hook
race_top:slot_tp_descr_get
race_top:type_set_name
race_top:set_tp_bases
race_top:type_set_bases_unlocked
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