fix race on utf8

Objects/unicodeobject.c

@@ -125,7 +125,7 @@ NOTE: In the interpreter's initialization phase, some globals are currently
     (assert(_PyUnicode_CHECK(op)),                      \
      PyUnicode_IS_COMPACT_ASCII(op) ?                   \
          _PyASCIIObject_CAST(op)->length :              \
-         FT_ATOMIC_LOAD_SSIZE(_PyUnicode_UTF8_LENGTH(op)))
+         FT_ATOMIC_LOAD_SSIZE_RELAXED(_PyUnicode_UTF8_LENGTH(op)))
 
 #define _PyUnicode_LENGTH(op)                           \
     (_PyASCIIObject_CAST(op)->length)
@@ -668,15 +668,15 @@ _PyUnicode_CheckConsistency(PyObject *op, int check_content)
             CHECK(data != NULL);
             if (ascii->state.ascii) {
                 CHECK(FT_ATOMIC_LOAD_PTR(compact->utf8) == data);
-                CHECK(FT_ATOMIC_LOAD_SSIZE(compact->utf8_length) == ascii->length);
+                CHECK(FT_ATOMIC_LOAD_SSIZE_RELAXED(compact->utf8_length) == ascii->length);
             }
             else {
                 CHECK(FT_ATOMIC_LOAD_PTR(compact->utf8) != data);
             }
         }
 
         if (FT_ATOMIC_LOAD_PTR(compact->utf8) == NULL)
-            CHECK(FT_ATOMIC_LOAD_SSIZE(compact->utf8_length) == ascii->length);
+            CHECK(FT_ATOMIC_LOAD_SSIZE_RELAXED(compact->utf8_length) == 0);
     }
 
     /* check that the best kind is used: O(n) operation */
@@ -5825,7 +5825,7 @@ unicode_fill_utf8(PyObject *unicode)
     assert(!PyUnicode_IS_ASCII(unicode));
     int ret = 0;
     Py_BEGIN_CRITICAL_SECTION(unicode);
-    if (FT_ATOMIC_LOAD_PTR_RELAXED(_PyUnicode_UTF8(unicode))) {
+    if (FT_ATOMIC_LOAD_PTR(_PyUnicode_UTF8(unicode))) {
         goto exit;
     }
     int kind = PyUnicode_KIND(unicode);