improve comments

python · kumaraditya303 · Mar 30, 2025 · Mar 25, 2025 · Mar 25, 2025 · Mar 25, 2025
commit b0e06a083539a280b9c20c61e445727fa6413a4f
diff --git a/Modules/_ctypes/_ctypes.c b/Modules/_ctypes/_ctypes.c
@@ -712,14 +712,16 @@ StructUnionType_init(PyObject *self, PyObject *args, PyObject *kwds, int isStruc
            return 0;
        }
        int ret = 0;
-        STGINFO_LOCK2(info, baseinfo);
+        STGINFO_LOCK(baseinfo);
        /* copy base info */
        ret = PyCStgInfo_clone(info, baseinfo);
        if (ret >= 0) {
-            stginfo_clear_dict_final_lock_held(info);
-            stginfo_set_dict_final_lock_held(baseinfo);
+            // clear the 'final' bit in the subclass info
+            // safe to modify without atomics as it is not exposed to other threads
+            info->dict_final = 0;
+            stginfo_set_dict_final_lock_held(baseinfo); /* set the 'final' flag in the baseclass info */
        }
-        STGINFO_UNLOCK2();
+        STGINFO_UNLOCK();
        return ret;
    }
    return 0;

diff --git a/Modules/_ctypes/ctypes.h b/Modules/_ctypes/ctypes.h
@@ -424,9 +424,7 @@ typedef struct {
 */

 #define STGINFO_LOCK(stginfo)   Py_BEGIN_CRITICAL_SECTION_MUT(&(stginfo)->mutex)
-#define STGINFO_LOCK2(stginfo1, stginfo2)   Py_BEGIN_CRITICAL_SECTION2_MUT(&(stginfo1)->mutex, &(stginfo2)->mutex)
 #define STGINFO_UNLOCK()        Py_END_CRITICAL_SECTION()
-#define STGINFO_UNLOCK2()       Py_END_CRITICAL_SECTION2()

 static inline int
 stginfo_get_dict_final(StgInfo *info)
@@ -455,13 +453,6 @@ stginfo_set_dict_final(StgInfo *info)
    STGINFO_UNLOCK();
 }

-static inline void
-stginfo_clear_dict_final_lock_held(StgInfo *info)
-{
-    _Py_CRITICAL_SECTION_ASSERT_MUTEX_LOCKED(&info->mutex);
-    FT_ATOMIC_STORE_INT(info->dict_final, 0);
-}
-
 extern int PyCStgInfo_clone(StgInfo *dst_info, StgInfo *src_info);
 extern void ctype_clear_stginfo(StgInfo *info);


diff --git a/Modules/_ctypes/stgdict.c b/Modules/_ctypes/stgdict.c
@@ -23,8 +23,6 @@
 int
 PyCStgInfo_clone(StgInfo *dst_info, StgInfo *src_info)
 {
-    _Py_CRITICAL_SECTION_ASSERT_MUTEX_LOCKED(&src_info->mutex);
-    _Py_CRITICAL_SECTION_ASSERT_MUTEX_LOCKED(&dst_info->mutex);
    Py_ssize_t size;

    ctype_clear_stginfo(dst_info);
@@ -36,6 +34,9 @@ PyCStgInfo_clone(StgInfo *dst_info, StgInfo *src_info)
    dst_info->ffi_type_pointer.elements = NULL;

    memcpy(dst_info, src_info, sizeof(StgInfo));
+#ifdef Py_GIL_DISABLED
+    dst_info->mutex = (PyMutex){0};
+#endif

    Py_XINCREF(dst_info->proto);
    Py_XINCREF(dst_info->argtypes);