Simplify asyncio loop fast path guard

Author: KRRT7

Modules/_asynciomodule.c

@@ -366,28 +366,40 @@ get_event_loop(asyncio_state *state)
 }
 
 
+static int
+is_asyncio_base_event_loop_type(PyTypeObject *loop_type)
+{
+    if (strcmp(loop_type->tp_name, "BaseEventLoop") != 0) {
+        return 0;
+    }
+
+    PyObject *module_name =
+        PyDict_GetItemWithError(loop_type->tp_dict, &_Py_ID(__module__));
+    if (module_name == NULL) {
+        if (PyErr_Occurred()) {
+            return -1;
+        }
+        return 0;
+    }
+
+    return (
+        PyUnicode_Check(module_name) &&
+        PyUnicode_CompareWithASCIIString(module_name, "asyncio.base_events") == 0
+    );
+}
+
 static int
 is_asyncio_base_event_loop_subclass(PyTypeObject *loop_type)
 {
     // The _asyncio module is imported from asyncio.events while
     // asyncio.base_events is still initializing, so we can't cache the
     // BaseEventLoop type during module init without creating an import cycle.
     for (PyTypeObject *base = loop_type; base != NULL; base = base->tp_base) {
-        if (strcmp(base->tp_name, "BaseEventLoop") != 0) {
-            continue;
-        }
-
-        PyObject *module_name =
-            PyDict_GetItemWithError(base->tp_dict, &_Py_ID(__module__));
-        if (module_name == NULL) {
-            if (PyErr_Occurred()) {
-                return -1;
-            }
-            continue;
+        int is_base_event_loop = is_asyncio_base_event_loop_type(base);
+        if (is_base_event_loop < 0) {
+            return -1;
         }
-
-        if (PyUnicode_Check(module_name) &&
-            PyUnicode_CompareWithASCIIString(module_name, "asyncio.base_events") == 0) {
+        if (is_base_event_loop) {
             return 1;
         }
     }
@@ -443,7 +455,10 @@ call_soon(asyncio_state *state, PyObject *loop, PyObject *func, PyObject *arg,
     int is_base_event_loop_subclass =
         is_asyncio_base_event_loop_subclass(loop_type);
     int is_stdlib_base_event_loop =
-        strcmp(loop_type->tp_name, "BaseEventLoop") == 0;
+        is_asyncio_base_event_loop_type(loop_type);
+    if (is_base_event_loop_subclass < 0 || is_stdlib_base_event_loop < 0) {
+        return -1;
+    }
     PyObject *call_soon_attr =
         PyDict_GetItemWithError(loop_type->tp_dict, &_Py_ID(call_soon));
     if (call_soon_attr == NULL && PyErr_Occurred()) {
@@ -454,15 +469,8 @@ call_soon(asyncio_state *state, PyObject *loop, PyObject *func, PyObject *arg,
         return -1;
     }
 
-    PyObject *module_name = PyDict_GetItemWithError(loop_type->tp_dict, &_Py_ID(__module__));
-    if (module_name == NULL && PyErr_Occurred()) {
-        return -1;
-    }
-
     int use_fastpath = (
         is_base_event_loop_subclass &&
-        module_name != NULL &&
-        PyUnicode_Check(module_name) &&
         // Only use the private fast path when the subclass keeps the public
         // call_soon() contract unchanged at both the type and instance level.
         !has_instance_call_soon_shadow &&