improve comments

Author: kumaraditya303

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;

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);
 

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);