data race in PyMember_GetOne with _Py_T_OBJECT #132685
Description
When running ctypes tests using parallel threads the following data race is reported:
WARNING: ThreadSanitizer: data race (pid=73865)
Read of size 8 at 0x7fadbc570760 by thread T1391:
#0 PyMember_GetOne /home/realkumaraditya/cpython/Python/structmember.c:88:13 (python+0x4deee7) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#1 member_get /home/realkumaraditya/cpython/Objects/descrobject.c:180:12 (python+0x207c4a) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#2 _PyObject_GenericGetAttrWithDict /home/realkumaraditya/cpython/Objects/object.c (python+0x2a8da2) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#3 PyObject_GenericGetAttr /home/realkumaraditya/cpython/Objects/object.c:1792:12 (python+0x2a8732) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#4 PyObject_GetAttr /home/realkumaraditya/cpython/Objects/object.c:1296:18 (python+0x2a70e7) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#5 _PyEval_EvalFrameDefault /home/realkumaraditya/cpython/Python/generated_cases.c.h:7710:30 (python+0x4111a8) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#6 _PyEval_EvalFrame /home/realkumaraditya/cpython/./Include/internal/pycore_ceval.h:119:16 (python+0x3f80ef) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#7 _PyEval_Vector /home/realkumaraditya/cpython/Python/ceval.c:1917:12 (python+0x3f80ef)
#8 PyEval_EvalCode /home/realkumaraditya/cpython/Python/ceval.c:829:21 (python+0x3f80ef)
#9 builtin_exec_impl /home/realkumaraditya/cpython/Python/bltinmodule.c:1158:17 (python+0x3f1937) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#10 builtin_exec /home/realkumaraditya/cpython/Python/clinic/bltinmodule.c.h:568:20 (python+0x3f1937)
#11 _PyEval_EvalFrameDefault /home/realkumaraditya/cpython/Python/generated_cases.c.h:2179:35 (python+0x3fff63) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#12 _PyEval_EvalFrame /home/realkumaraditya/cpython/./Include/internal/pycore_ceval.h:119:16 (python+0x3f85b0) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#13 _PyEval_Vector /home/realkumaraditya/cpython/Python/ceval.c:1917:12 (python+0x3f85b0)
#14 _PyFunction_Vectorcall /home/realkumaraditya/cpython/Objects/call.c (python+0x1f1a8f) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#15 _PyObject_VectorcallTstate /home/realkumaraditya/cpython/./Include/internal/pycore_call.h:169:11 (python+0x1f6460) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#16 method_vectorcall /home/realkumaraditya/cpython/Objects/classobject.c:94:18 (python+0x1f6460)
#17 _PyVectorcall_Call /home/realkumaraditya/cpython/Objects/call.c:273:16 (python+0x1f171f) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#18 _PyObject_Call /home/realkumaraditya/cpython/Objects/call.c:348:16 (python+0x1f171f)
#19 PyObject_Call /home/realkumaraditya/cpython/Objects/call.c:373:12 (python+0x1f1785) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#20 _PyEval_EvalFrameDefault /home/realkumaraditya/cpython/Python/generated_cases.c.h:2448:32 (python+0x400a72) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#21 _PyEval_EvalFrame /home/realkumaraditya/cpython/./Include/internal/pycore_ceval.h:119:16 (python+0x3f85b0) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#22 _PyEval_Vector /home/realkumaraditya/cpython/Python/ceval.c:1917:12 (python+0x3f85b0)
#23 _PyFunction_Vectorcall /home/realkumaraditya/cpython/Objects/call.c (python+0x1f1a8f) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#24 _PyObject_VectorcallTstate /home/realkumaraditya/cpython/./Include/internal/pycore_call.h:169:11 (python+0x1f63af) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#25 method_vectorcall /home/realkumaraditya/cpython/Objects/classobject.c:72:20 (python+0x1f63af)
#26 _PyObject_VectorcallTstate /home/realkumaraditya/cpython/./Include/internal/pycore_call.h:169:11 (python+0x450517) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#27 context_run /home/realkumaraditya/cpython/Python/context.c:728:29 (python+0x450517)
#28 _PyEval_EvalFrameDefault /home/realkumaraditya/cpython/Python/generated_cases.c.h:3507:35 (python+0x404c09) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#29 _PyEval_EvalFrame /home/realkumaraditya/cpython/./Include/internal/pycore_ceval.h:119:16 (python+0x3f85b0) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#30 _PyEval_Vector /home/realkumaraditya/cpython/Python/ceval.c:1917:12 (python+0x3f85b0)
#31 _PyFunction_Vectorcall /home/realkumaraditya/cpython/Objects/call.c (python+0x1f1a8f) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#32 _PyObject_VectorcallTstate /home/realkumaraditya/cpython/./Include/internal/pycore_call.h:169:11 (python+0x1f63af) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#33 method_vectorcall /home/realkumaraditya/cpython/Objects/classobject.c:72:20 (python+0x1f63af)
#34 _PyVectorcall_Call /home/realkumaraditya/cpython/Objects/call.c:273:16 (python+0x1f171f) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#35 _PyObject_Call /home/realkumaraditya/cpython/Objects/call.c:348:16 (python+0x1f171f)
#36 PyObject_Call /home/realkumaraditya/cpython/Objects/call.c:373:12 (python+0x1f1785) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#37 thread_run /home/realkumaraditya/cpython/./Modules/_threadmodule.c:353:21 (python+0x59f302) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#38 pythread_wrapper /home/realkumaraditya/cpython/Python/thread_pthread.h:242:5 (python+0x4f8be7) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
Previous write of size 8 at 0x7fadbc570760 by thread T1392:
#0 PyCData_GetContainer /home/realkumaraditya/cpython/./Modules/_ctypes/_ctypes.c:2840:29 (_ctypes.cpython-314t-x86_64-linux-gnu.so+0xbce8) (BuildId: add85487867eb2c9394b8c302c674d3f18d2bee0)
#1 KeepRef_lock_held /home/realkumaraditya/cpython/./Modules/_ctypes/_ctypes.c:2900:10 (_ctypes.cpython-314t-x86_64-linux-gnu.so+0x98f6) (BuildId: add85487867eb2c9394b8c302c674d3f18d2bee0)
#2 KeepRef /home/realkumaraditya/cpython/./Modules/_ctypes/_ctypes.c:2943:11 (_ctypes.cpython-314t-x86_64-linux-gnu.so+0x98f6)
#3 PyCData_set /home/realkumaraditya/cpython/./Modules/_ctypes/_ctypes.c:3505:12 (_ctypes.cpython-314t-x86_64-linux-gnu.so+0x17fdc) (BuildId: add85487867eb2c9394b8c302c674d3f18d2bee0)
#4 Array_ass_item_lock_held /home/realkumaraditya/cpython/./Modules/_ctypes/_ctypes.c:5094:12 (_ctypes.cpython-314t-x86_64-linux-gnu.so+0x17fdc)
#5 Array_ass_subscript_lock_held /home/realkumaraditya/cpython/./Modules/_ctypes/_ctypes.c:5127:16 (_ctypes.cpython-314t-x86_64-linux-gnu.so+0x179eb) (BuildId: add85487867eb2c9394b8c302c674d3f18d2bee0)
#6 Array_ass_subscript /home/realkumaraditya/cpython/./Modules/_ctypes/_ctypes.c:5171:14 (_ctypes.cpython-314t-x86_64-linux-gnu.so+0x179eb)
#7 PyObject_SetItem /home/realkumaraditya/cpython/Objects/abstract.c:235:19 (python+0x1b9598) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#8 _PyEval_EvalFrameDefault /home/realkumaraditya/cpython/Python/generated_cases.c.h:11172:27 (python+0x41b90a) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#9 _PyEval_EvalFrame /home/realkumaraditya/cpython/./Include/internal/pycore_ceval.h:119:16 (python+0x3f80ef) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#10 _PyEval_Vector /home/realkumaraditya/cpython/Python/ceval.c:1917:12 (python+0x3f80ef)
#11 PyEval_EvalCode /home/realkumaraditya/cpython/Python/ceval.c:829:21 (python+0x3f80ef)
#12 builtin_exec_impl /home/realkumaraditya/cpython/Python/bltinmodule.c:1158:17 (python+0x3f1937) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#13 builtin_exec /home/realkumaraditya/cpython/Python/clinic/bltinmodule.c.h:568:20 (python+0x3f1937)
#14 _PyEval_EvalFrameDefault /home/realkumaraditya/cpython/Python/generated_cases.c.h:2179:35 (python+0x3fff63) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#15 _PyEval_EvalFrame /home/realkumaraditya/cpython/./Include/internal/pycore_ceval.h:119:16 (python+0x3f85b0) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#16 _PyEval_Vector /home/realkumaraditya/cpython/Python/ceval.c:1917:12 (python+0x3f85b0)
#17 _PyFunction_Vectorcall /home/realkumaraditya/cpython/Objects/call.c (python+0x1f1a8f) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#18 _PyObject_VectorcallTstate /home/realkumaraditya/cpython/./Include/internal/pycore_call.h:169:11 (python+0x1f6460) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#19 method_vectorcall /home/realkumaraditya/cpython/Objects/classobject.c:94:18 (python+0x1f6460)
#20 _PyVectorcall_Call /home/realkumaraditya/cpython/Objects/call.c:273:16 (python+0x1f171f) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#21 _PyObject_Call /home/realkumaraditya/cpython/Objects/call.c:348:16 (python+0x1f171f)
#22 PyObject_Call /home/realkumaraditya/cpython/Objects/call.c:373:12 (python+0x1f1785) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#23 _PyEval_EvalFrameDefault /home/realkumaraditya/cpython/Python/generated_cases.c.h:2448:32 (python+0x400a72) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#24 _PyEval_EvalFrame /home/realkumaraditya/cpython/./Include/internal/pycore_ceval.h:119:16 (python+0x3f85b0) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#25 _PyEval_Vector /home/realkumaraditya/cpython/Python/ceval.c:1917:12 (python+0x3f85b0)
#26 _PyFunction_Vectorcall /home/realkumaraditya/cpython/Objects/call.c (python+0x1f1a8f) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#27 _PyObject_VectorcallTstate /home/realkumaraditya/cpython/./Include/internal/pycore_call.h:169:11 (python+0x1f63af) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#28 method_vectorcall /home/realkumaraditya/cpython/Objects/classobject.c:72:20 (python+0x1f63af)
#29 _PyObject_VectorcallTstate /home/realkumaraditya/cpython/./Include/internal/pycore_call.h:169:11 (python+0x450517) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#30 context_run /home/realkumaraditya/cpython/Python/context.c:728:29 (python+0x450517)
#31 _PyEval_EvalFrameDefault /home/realkumaraditya/cpython/Python/generated_cases.c.h:3507:35 (python+0x404c09) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#32 _PyEval_EvalFrame /home/realkumaraditya/cpython/./Include/internal/pycore_ceval.h:119:16 (python+0x3f85b0) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#33 _PyEval_Vector /home/realkumaraditya/cpython/Python/ceval.c:1917:12 (python+0x3f85b0)
#34 _PyFunction_Vectorcall /home/realkumaraditya/cpython/Objects/call.c (python+0x1f1a8f) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#35 _PyObject_VectorcallTstate /home/realkumaraditya/cpython/./Include/internal/pycore_call.h:169:11 (python+0x1f63af) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#36 method_vectorcall /home/realkumaraditya/cpython/Objects/classobject.c:72:20 (python+0x1f63af)
#37 _PyVectorcall_Call /home/realkumaraditya/cpython/Objects/call.c:273:16 (python+0x1f171f) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#38 _PyObject_Call /home/realkumaraditya/cpython/Objects/call.c:348:16 (python+0x1f171f)
#39 PyObject_Call /home/realkumaraditya/cpython/Objects/call.c:373:12 (python+0x1f1785) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#40 thread_run /home/realkumaraditya/cpython/./Modules/_threadmodule.c:353:21 (python+0x59f302) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
#41 pythread_wrapper /home/realkumaraditya/cpython/Python/thread_pthread.h:242:5 (python+0x4f8be7) (BuildId: f96651439547347e4e969de5af0d9edea510d7e3)
SUMMARY: ThreadSanitizer: data race /home/realkumaraditya/cpython/Python/structmember.c:88:13 in PyMember_GetOne
==================
The data race is because when _Py_T_OBJECT is used, it currently reads the field non atomically without critical section. It needs to load it using atomics like Py_T_OBJECT_EX.