gh-116738: Make _abc module thread-safe (#117488)

A collection of small changes aimed at making the `_abc` module safe to
use in a free-threaded build.

1 files changed, 46 insertions, 0 deletions

diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index e9f2d25..3f38abf 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -5117,6 +5117,52 @@ _PyType_LookupId(PyTypeObject *type, _Py_Identifier *name)
     return _PyType_Lookup(type, oname);
 }
 
+static void
+set_flags(PyTypeObject *self, unsigned long mask, unsigned long flags)
+{
+    ASSERT_TYPE_LOCK_HELD();
+    self->tp_flags = (self->tp_flags & ~mask) | flags;
+}
+
+void
+_PyType_SetFlags(PyTypeObject *self, unsigned long mask, unsigned long flags)
+{
+    BEGIN_TYPE_LOCK();
+    set_flags(self, mask, flags);
+    END_TYPE_LOCK();
+}
+
+static void
+set_flags_recursive(PyTypeObject *self, unsigned long mask, unsigned long flags)
+{
+    if (PyType_HasFeature(self, Py_TPFLAGS_IMMUTABLETYPE) ||
+        (self->tp_flags & mask) == flags)
+    {
+        return;
+    }
+
+    set_flags(self, mask, flags);
+
+    PyObject *children = _PyType_GetSubclasses(self);
+    if (children == NULL) {
+        return;
+    }
+
+    for (Py_ssize_t i = 0; i < PyList_GET_SIZE(children); i++) {
+        PyObject *child = PyList_GET_ITEM(children, i);
+        set_flags_recursive((PyTypeObject *)child, mask, flags);
+    }
+    Py_DECREF(children);
+}
+
+void
+_PyType_SetFlagsRecursive(PyTypeObject *self, unsigned long mask, unsigned long flags)
+{
+    BEGIN_TYPE_LOCK();
+    set_flags_recursive(self, mask, flags);
+    END_TYPE_LOCK();
+}
+
 /* This is similar to PyObject_GenericGetAttr(),
    but uses _PyType_Lookup() instead of just looking in type->tp_dict.