https://github.com/python/cpython/commit/b9d2ee687cfca6365e26e156b1e22824b16dabb8
commit: b9d2ee687cfca6365e26e156b1e22824b16dabb8
branch: main
author: Sam Gross <[email protected]>
committer: encukou <[email protected]>
date: 2025-02-17T14:15:40+01:00
summary:
gh-129701: Fix a data race in `intern_common` in the free threaded build
(GH-130089)
* gh-129701: Fix a data race in `intern_common` in the free threaded build
* Use a mutex to avoid potentially returning a non-immortalized string,
because immortalization happens after the insertion into the interned
dict.
* Use `Py_DECREF()` calls instead of `Py_SET_REFCNT(s, Py_REFCNT(s) - 2)`
for thread-safety. This code path isn't performance sensistive, so
just use `Py_DECREF()` unconditionally for simplicity.
files:
M Include/internal/pycore_global_objects.h
M Objects/unicodeobject.c
diff --git a/Include/internal/pycore_global_objects.h
b/Include/internal/pycore_global_objects.h
index e3f7ac707f0c37..611f01d1c32710 100644
--- a/Include/internal/pycore_global_objects.h
+++ b/Include/internal/pycore_global_objects.h
@@ -64,6 +64,9 @@ struct _Py_static_objects {
(interp)->cached_objects.NAME
struct _Py_interp_cached_objects {
+#ifdef Py_GIL_DISABLED
+ PyMutex interned_mutex;
+#endif
PyObject *interned_strings;
/* object.__reduce__ */
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 371c358a4950c2..03f15b37598363 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -112,6 +112,14 @@ NOTE: In the interpreter's initialization phase, some
globals are currently
# define _PyUnicode_CHECK(op) PyUnicode_Check(op)
#endif
+#ifdef Py_GIL_DISABLED
+# define LOCK_INTERNED(interp) PyMutex_Lock(&_Py_INTERP_CACHED_OBJECT(interp,
interned_mutex))
+# define UNLOCK_INTERNED(interp)
PyMutex_Unlock(&_Py_INTERP_CACHED_OBJECT(interp, interned_mutex))
+#else
+# define LOCK_INTERNED(interp)
+# define UNLOCK_INTERNED(interp)
+#endif
+
static inline char* _PyUnicode_UTF8(PyObject *op)
{
return FT_ATOMIC_LOAD_PTR_ACQUIRE(_PyCompactUnicodeObject_CAST(op)->utf8);
@@ -15814,11 +15822,13 @@ intern_common(PyInterpreterState *interp, PyObject *s
/* stolen */,
PyObject *interned = get_interned_dict(interp);
assert(interned != NULL);
+ LOCK_INTERNED(interp);
PyObject *t;
{
int res = PyDict_SetDefaultRef(interned, s, s, &t);
if (res < 0) {
PyErr_Clear();
+ UNLOCK_INTERNED(interp);
return s;
}
else if (res == 1) {
@@ -15828,6 +15838,7 @@ intern_common(PyInterpreterState *interp, PyObject *s
/* stolen */,
PyUnicode_CHECK_INTERNED(t) == SSTATE_INTERNED_MORTAL) {
immortalize_interned(t);
}
+ UNLOCK_INTERNED(interp);
return t;
}
else {
@@ -15844,12 +15855,8 @@ intern_common(PyInterpreterState *interp, PyObject *s
/* stolen */,
if (!_Py_IsImmortal(s)) {
/* The two references in interned dict (key and value) are not counted.
unicode_dealloc() and _PyUnicode_ClearInterned() take care of this. */
- Py_SET_REFCNT(s, Py_REFCNT(s) - 2);
-#ifdef Py_REF_DEBUG
- /* let's be pedantic with the ref total */
- _Py_DecRefTotal(_PyThreadState_GET());
- _Py_DecRefTotal(_PyThreadState_GET());
-#endif
+ Py_DECREF(s);
+ Py_DECREF(s);
}
FT_ATOMIC_STORE_UINT16_RELAXED(_PyUnicode_STATE(s).interned,
SSTATE_INTERNED_MORTAL);
@@ -15864,6 +15871,7 @@ intern_common(PyInterpreterState *interp, PyObject *s
/* stolen */,
immortalize_interned(s);
}
+ UNLOCK_INTERNED(interp);
return s;
}
_______________________________________________
Python-checkins mailing list -- [email protected]
To unsubscribe send an email to [email protected]
https://mail.python.org/mailman3/lists/python-checkins.python.org/
Member address: [email protected]
