From 19755e18457bc8f16e119bc5366a2f8632ff647c Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Fri, 14 Jun 2024 16:05:51 -0600
Subject: [PATCH] Avoid a race on
 _PyRuntime.types.managed_static.types[i].interp_count.

Closes: https://github.com/python/cpython/pull/120529
---
 Include/internal/pycore_typeobject.h | 1 +
 Objects/typeobject.c                 | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/Include/internal/pycore_typeobject.h b/Include/internal/pycore_typeobject.h
index 05f125f928ca68..e1d9e109f77d9b 100644
--- a/Include/internal/pycore_typeobject.h
+++ b/Include/internal/pycore_typeobject.h
@@ -31,6 +31,7 @@ struct _types_runtime_state {
     unsigned int next_version_tag;
 
     struct {
+        PyMutex mutex;
         struct {
             PyTypeObject *type;
             int64_t interp_count;
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index f55b77a6e544f2..44ca7211fbad76 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -244,9 +244,11 @@ managed_static_type_state_init(PyInterpreterState *interp, PyTypeObject *self,
         ? index
         : index + _Py_MAX_MANAGED_STATIC_BUILTIN_TYPES;
 
+    PyMutex_Lock(&_PyRuntime.types.managed_static.mutex);
     assert((initial == 1) ==
             (_PyRuntime.types.managed_static.types[full_index].interp_count == 0));
     _PyRuntime.types.managed_static.types[full_index].interp_count += 1;
+    PyMutex_Unlock(&_PyRuntime.types.managed_static.mutex);
 
     if (initial) {
         assert(_PyRuntime.types.managed_static.types[full_index].type == NULL);
@@ -300,7 +302,9 @@ managed_static_type_state_clear(PyInterpreterState *interp, PyTypeObject *self,
     state->type = NULL;
     assert(state->tp_weaklist == NULL);  // It was already cleared out.
 
+    PyMutex_Lock(&_PyRuntime.types.managed_static.mutex);
     _PyRuntime.types.managed_static.types[full_index].interp_count -= 1;
+    PyMutex_Unlock(&_PyRuntime.types.managed_static.mutex);
     if (final) {
         assert(!_PyRuntime.types.managed_static.types[full_index].interp_count);
         _PyRuntime.types.managed_static.types[full_index].type = NULL;