From 2fbc9861c3b1325095019b3df6f3b5b0a1235f1f Mon Sep 17 00:00:00 2001
From: Sam Gross <colesbury@gmail.com>
Date: Wed, 12 Feb 2025 10:43:25 -0500
Subject: [PATCH] [3.13] gh-128759: Fix accesses to `tp_version_tag`.
 (GH-129750) (GH-130042)

We should use a relaxed atomic load in the free threading build in
`PyType_Modified()` because that's called without the type lock held.
It's not necessary to use atomics in `type_modified_unlocked()`.

We should also use `FT_ATOMIC_STORE_UINT_RELAXED()` instead of the
`UINT32` variant because `tp_version_tag` is declared as `unsigned int`.
(cherry picked from commit 57f45ee2d8ee23c2a1d1daba4095a5a044169419)
---
 .../internal/pycore_pyatomic_ft_wrappers.h    | 73 ++++++++++++++++++-
 Objects/typeobject.c                          | 11 +--
 2 files changed, 75 insertions(+), 9 deletions(-)

diff --git a/Include/internal/pycore_pyatomic_ft_wrappers.h b/Include/internal/pycore_pyatomic_ft_wrappers.h
index a1bb383bcd22..d755d03a5fa1 100644
--- a/Include/internal/pycore_pyatomic_ft_wrappers.h
+++ b/Include/internal/pycore_pyatomic_ft_wrappers.h
@@ -61,6 +61,54 @@ extern "C" {
     _Py_atomic_store_uint16_relaxed(&value, new_value)
 #define FT_ATOMIC_STORE_UINT32_RELAXED(value, new_value) \
     _Py_atomic_store_uint32_relaxed(&value, new_value)
+#define FT_ATOMIC_STORE_CHAR_RELAXED(value, new_value) \
+    _Py_atomic_store_char_relaxed(&value, new_value)
+#define FT_ATOMIC_LOAD_CHAR_RELAXED(value) \
+    _Py_atomic_load_char_relaxed(&value)
+#define FT_ATOMIC_STORE_UCHAR_RELAXED(value, new_value) \
+    _Py_atomic_store_uchar_relaxed(&value, new_value)
+#define FT_ATOMIC_LOAD_UCHAR_RELAXED(value) \
+    _Py_atomic_load_uchar_relaxed(&value)
+#define FT_ATOMIC_STORE_SHORT_RELAXED(value, new_value) \
+    _Py_atomic_store_short_relaxed(&value, new_value)
+#define FT_ATOMIC_LOAD_SHORT_RELAXED(value) \
+    _Py_atomic_load_short_relaxed(&value)
+#define FT_ATOMIC_STORE_USHORT_RELAXED(value, new_value) \
+    _Py_atomic_store_ushort_relaxed(&value, new_value)
+#define FT_ATOMIC_LOAD_USHORT_RELAXED(value) \
+    _Py_atomic_load_ushort_relaxed(&value)
+#define FT_ATOMIC_STORE_INT_RELAXED(value, new_value) \
+    _Py_atomic_store_int_relaxed(&value, new_value)
+#define FT_ATOMIC_LOAD_INT_RELAXED(value) \
+    _Py_atomic_load_int_relaxed(&value)
+#define FT_ATOMIC_STORE_UINT_RELAXED(value, new_value) \
+    _Py_atomic_store_uint_relaxed(&value, new_value)
+#define FT_ATOMIC_LOAD_UINT_RELAXED(value) \
+    _Py_atomic_load_uint_relaxed(&value)
+#define FT_ATOMIC_STORE_LONG_RELAXED(value, new_value) \
+    _Py_atomic_store_long_relaxed(&value, new_value)
+#define FT_ATOMIC_LOAD_LONG_RELAXED(value) \
+    _Py_atomic_load_long_relaxed(&value)
+#define FT_ATOMIC_STORE_ULONG_RELAXED(value, new_value) \
+    _Py_atomic_store_ulong_relaxed(&value, new_value)
+#define FT_ATOMIC_STORE_SSIZE_RELAXED(value, new_value) \
+    _Py_atomic_store_ssize_relaxed(&value, new_value)
+#define FT_ATOMIC_STORE_FLOAT_RELAXED(value, new_value) \
+    _Py_atomic_store_float_relaxed(&value, new_value)
+#define FT_ATOMIC_LOAD_FLOAT_RELAXED(value) \
+    _Py_atomic_load_float_relaxed(&value)
+#define FT_ATOMIC_STORE_DOUBLE_RELAXED(value, new_value) \
+    _Py_atomic_store_double_relaxed(&value, new_value)
+#define FT_ATOMIC_LOAD_DOUBLE_RELAXED(value) \
+    _Py_atomic_load_double_relaxed(&value)
+#define FT_ATOMIC_STORE_LLONG_RELAXED(value, new_value) \
+    _Py_atomic_store_llong_relaxed(&value, new_value)
+#define FT_ATOMIC_LOAD_LLONG_RELAXED(value) \
+    _Py_atomic_load_llong_relaxed(&value)
+#define FT_ATOMIC_STORE_ULLONG_RELAXED(value, new_value) \
+    _Py_atomic_store_ullong_relaxed(&value, new_value)
+#define FT_ATOMIC_LOAD_ULLONG_RELAXED(value) \
+    _Py_atomic_load_ullong_relaxed(&value)
 
 #else
 #define FT_ATOMIC_LOAD_PTR(value) value
@@ -68,7 +116,6 @@ extern "C" {
 #define FT_ATOMIC_LOAD_SSIZE(value) value
 #define FT_ATOMIC_LOAD_SSIZE_ACQUIRE(value) value
 #define FT_ATOMIC_LOAD_SSIZE_RELAXED(value) value
-#define FT_ATOMIC_STORE_PTR(value, new_value) value = new_value
 #define FT_ATOMIC_LOAD_PTR_ACQUIRE(value) value
 #define FT_ATOMIC_LOAD_UINTPTR_ACQUIRE(value) value
 #define FT_ATOMIC_LOAD_PTR_RELAXED(value) value
@@ -85,6 +132,30 @@ extern "C" {
 #define FT_ATOMIC_STORE_UINT8_RELAXED(value, new_value) value = new_value
 #define FT_ATOMIC_STORE_UINT16_RELAXED(value, new_value) value = new_value
 #define FT_ATOMIC_STORE_UINT32_RELAXED(value, new_value) value = new_value
+#define FT_ATOMIC_LOAD_CHAR_RELAXED(value) value
+#define FT_ATOMIC_STORE_CHAR_RELAXED(value, new_value) value = new_value
+#define FT_ATOMIC_LOAD_UCHAR_RELAXED(value) value
+#define FT_ATOMIC_STORE_UCHAR_RELAXED(value, new_value) value = new_value
+#define FT_ATOMIC_LOAD_SHORT_RELAXED(value) value
+#define FT_ATOMIC_STORE_SHORT_RELAXED(value, new_value) value = new_value
+#define FT_ATOMIC_LOAD_USHORT_RELAXED(value) value
+#define FT_ATOMIC_STORE_USHORT_RELAXED(value, new_value) value = new_value
+#define FT_ATOMIC_LOAD_INT_RELAXED(value) value
+#define FT_ATOMIC_STORE_INT_RELAXED(value, new_value) value = new_value
+#define FT_ATOMIC_LOAD_UINT_RELAXED(value) value
+#define FT_ATOMIC_STORE_UINT_RELAXED(value, new_value) value = new_value
+#define FT_ATOMIC_LOAD_LONG_RELAXED(value) value
+#define FT_ATOMIC_STORE_LONG_RELAXED(value, new_value) value = new_value
+#define FT_ATOMIC_STORE_ULONG_RELAXED(value, new_value) value = new_value
+#define FT_ATOMIC_STORE_SSIZE_RELAXED(value, new_value) value = new_value
+#define FT_ATOMIC_LOAD_FLOAT_RELAXED(value) value
+#define FT_ATOMIC_STORE_FLOAT_RELAXED(value, new_value) value = new_value
+#define FT_ATOMIC_LOAD_DOUBLE_RELAXED(value) value
+#define FT_ATOMIC_STORE_DOUBLE_RELAXED(value, new_value) value = new_value
+#define FT_ATOMIC_LOAD_LLONG_RELAXED(value) value
+#define FT_ATOMIC_STORE_LLONG_RELAXED(value, new_value) value = new_value
+#define FT_ATOMIC_LOAD_ULLONG_RELAXED(value) value
+#define FT_ATOMIC_STORE_ULLONG_RELAXED(value, new_value) value = new_value
 
 #endif
 
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index bd79676b8e92..57e03c669d91 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -975,7 +975,7 @@ set_version_unlocked(PyTypeObject *tp, unsigned int version)
         _Py_atomic_add_uint16(&tp->tp_versions_used, 1);
     }
 #endif
-    FT_ATOMIC_STORE_UINT32_RELAXED(tp->tp_version_tag, version);
+    FT_ATOMIC_STORE_UINT_RELAXED(tp->tp_version_tag, version);
 }
 
 static void
@@ -996,15 +996,10 @@ type_modified_unlocked(PyTypeObject *type)
        We don't assign new version tags eagerly, but only as
        needed.
      */
-#ifdef Py_GIL_DISABLED
-    if (_Py_atomic_load_uint_relaxed(&type->tp_version_tag) == 0) {
-        return;
-    }
-#else
+    ASSERT_TYPE_LOCK_HELD();
     if (type->tp_version_tag == 0) {
         return;
     }
-#endif
     // Cannot modify static builtin types.
     assert((type->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN) == 0);
 
@@ -1056,7 +1051,7 @@ void
 PyType_Modified(PyTypeObject *type)
 {
     // Quick check without the lock held
-    if (type->tp_version_tag == 0) {
+    if (FT_ATOMIC_LOAD_UINT_RELAXED(type->tp_version_tag) == 0) {
         return;
     }
 
-- 
2.47.3