[3.13] gh-128759: fix data race in `type_modified_unlocked` (GH-128764) (#128769)

* gh-128759: fix data race in `type_modified_unlocked` (GH-128764)
(cherry picked from commit 6e1e78054060ad326f26dd8dbf12adfedbb52883)

Co-authored-by: sobolevn <mail@sobolevn.me>

diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 093ebac9b50179624f6c8649d49d5bb4e3b89e30..bd79676b8e925fbbe58dcaa528f7fc93b71f8eee 100644 (file)
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -996,9 +996,15 @@ type_modified_unlocked(PyTypeObject *type)
        We don't assign new version tags eagerly, but only as
        needed.
      */
+#ifdef Py_GIL_DISABLED
+    if (_Py_atomic_load_uint_relaxed(&type->tp_version_tag) == 0) {
+        return;
+    }
+#else
     if (type->tp_version_tag == 0) {
         return;
     }
+#endif
     // Cannot modify static builtin types.
     assert((type->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN) == 0);