gh-128759: fix data race in type_modified_unlocked (#128764)

sobolevn · web-flow · commit 6e1e78054060 · 2025-01-13T07:40:52.000Z
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
@@ -1038,7 +1038,7 @@ type_modified_unlocked(PyTypeObject *type)
        We don't assign new version tags eagerly, but only as
        needed.
      */
-    if (type->tp_version_tag == 0) {
+    if (FT_ATOMIC_LOAD_UINT_RELAXED(type->tp_version_tag) == 0) {
         return;
     }
     // Cannot modify static builtin types.

Original file line number	Diff line number	Diff line change
`@@ -1038,7 +1038,7 @@ type_modified_unlocked(PyTypeObject *type)`
`1038`	`1038`	`We don't assign new version tags eagerly, but only as`
`1039`	`1039`	`needed.`
`1040`	`1040`	`*/`
`1041`		`- if (type->tp_version_tag == 0) {`
	`1041`	`+ if (FT_ATOMIC_LOAD_UINT_RELAXED(type->tp_version_tag) == 0) {`
`1042`	`1042`	`return;`
`1043`	`1043`	`}`
`1044`	`1044`	`// Cannot modify static builtin types.`