From 7f428bb8be8bbe8e6441fc4bca9c4dd2486be2d3 Mon Sep 17 00:00:00 2001 From: Kumar Aditya Date: Fri, 1 Aug 2025 19:10:40 +0530 Subject: [PATCH] gh-133467: fix data race in `type_set_name` (GH-137302) Fix data race in `type_set_name` by assigning name under stop the world pause making it thread safe in free-threading. (cherry picked from commit e99bc7fd44bbbf2464c37d5a57777ac0e1264c37) Co-authored-by: Kumar Aditya --- Lib/test/test_free_threading/test_type.py | 14 ++++++++++++++ Objects/typeobject.c | 10 ++++++++-- Tools/tsan/suppressions_free_threading.txt | 2 -- 3 files changed, 22 insertions(+), 4 deletions(-) diff --git a/Lib/test/test_free_threading/test_type.py b/Lib/test/test_free_threading/test_type.py index ae996e7db3c7fd..2d995751005d71 100644 --- a/Lib/test/test_free_threading/test_type.py +++ b/Lib/test/test_free_threading/test_type.py @@ -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) diff --git a/Objects/typeobject.c b/Objects/typeobject.c index ab6ad1fe8b5f91..7a2cc68876d76b 100644 --- a/Objects/typeobject.c +++ b/Objects/typeobject.c @@ -1434,9 +1434,13 @@ 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; } @@ -10403,9 +10407,11 @@ 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) diff --git a/Tools/tsan/suppressions_free_threading.txt b/Tools/tsan/suppressions_free_threading.txt index 3230f969436c82..2795ee1ba4c45c 100644 --- a/Tools/tsan/suppressions_free_threading.txt +++ b/Tools/tsan/suppressions_free_threading.txt @@ -51,7 +51,5 @@ race:PyObject_Realloc # gh-133467. Some of these could be hard to trigger. race_top:update_one_slot 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