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gh-129824: fix data races in subinterpreters under TSAN (#135794)

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This fixes the data races in typeobject.c in subinterpreters under free-threading. The type flags and slots are only modified in the main interpreter as all static types are first initialised in main interpreter.
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Kumar Aditya 2025-07-04 09:18:55 +05:30 • committed by GitHub
parent 85f092f541
commit b582d751b4
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GPG key ID: B5690EEEBB952194
1 changed files with 44 additions and 17 deletions
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61
Objects/typeobject.c
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@ -54,7 +54,6 @@ class object "PyObject *" "&PyBaseObject_Type"
PyUnicode_CheckExact(name) && \
(PyUnicode_GET_LENGTH(name) <= MCACHE_MAX_ATTR_SIZE)
#define NEXT_GLOBAL_VERSION_TAG _PyRuntime.types.next_version_tag
#define NEXT_VERSION_TAG(interp) \
(interp)->types.next_version_tag
@ -266,8 +265,8 @@ static_ext_type_lookup(PyInterpreterState *interp, size_t index,
assert(index < _Py_MAX_MANAGED_STATIC_EXT_TYPES);
size_t full_index = index + _Py_MAX_MANAGED_STATIC_BUILTIN_TYPES;
int64_t interp_count =
_PyRuntime.types.managed_static.types[full_index].interp_count;
int64_t interp_count = _Py_atomic_load_int64(
&_PyRuntime.types.managed_static.types[full_index].interp_count);
assert((interp_count == 0) ==
(_PyRuntime.types.managed_static.types[full_index].type == NULL));
*p_interp_count = interp_count;
@ -344,7 +343,7 @@ managed_static_type_state_init(PyInterpreterState *interp, PyTypeObject *self,
: index + _Py_MAX_MANAGED_STATIC_BUILTIN_TYPES;
assert((initial == 1) ==
(_PyRuntime.types.managed_static.types[full_index].interp_count == 0));
(_Py_atomic_load_int64(&_PyRuntime.types.managed_static.types[full_index].interp_count) == 0));
(void)_Py_atomic_add_int64(
&_PyRuntime.types.managed_static.types[full_index].interp_count, 1);
@ -393,7 +392,7 @@ managed_static_type_state_clear(PyInterpreterState *interp, PyTypeObject *self,
: &(interp->types.for_extensions.initialized[index]);
assert(state != NULL);
assert(_PyRuntime.types.managed_static.types[full_index].interp_count > 0);
assert(_Py_atomic_load_int64(&_PyRuntime.types.managed_static.types[full_index].interp_count) > 0);
assert(_PyRuntime.types.managed_static.types[full_index].type == state->type);
assert(state->type != NULL);
@ -403,7 +402,7 @@ managed_static_type_state_clear(PyInterpreterState *interp, PyTypeObject *self,
(void)_Py_atomic_add_int64(
&_PyRuntime.types.managed_static.types[full_index].interp_count, -1);
if (final) {
assert(!_PyRuntime.types.managed_static.types[full_index].interp_count);
assert(!_Py_atomic_load_int64(&_PyRuntime.types.managed_static.types[full_index].interp_count));
_PyRuntime.types.managed_static.types[full_index].type = NULL;
managed_static_type_index_clear(self);
@ -1359,6 +1358,19 @@ _PyType_LookupByVersion(unsigned int version)
#error "_Py_ATTR_CACHE_UNUSED must be bigger than max"
#endif
static inline unsigned int
next_global_version_tag(void)
{
unsigned int old;
do {
old = _Py_atomic_load_uint_relaxed(&_PyRuntime.types.next_version_tag);
if (old >= _Py_MAX_GLOBAL_TYPE_VERSION_TAG) {
return 0;
}
} while (!_Py_atomic_compare_exchange_uint(&_PyRuntime.types.next_version_tag, &old, old + 1));
return old + 1;
}
static int
assign_version_tag(PyInterpreterState *interp, PyTypeObject *type)
{
@ -1389,11 +1401,12 @@ assign_version_tag(PyInterpreterState *interp, PyTypeObject *type)
}
if (type->tp_flags & Py_TPFLAGS_IMMUTABLETYPE) {
/* static types */
if (NEXT_GLOBAL_VERSION_TAG > _Py_MAX_GLOBAL_TYPE_VERSION_TAG) {
unsigned int next_version_tag = next_global_version_tag();
if (next_version_tag == 0) {
/* We have run out of version numbers */
return 0;
}
set_version_unlocked(type, NEXT_GLOBAL_VERSION_TAG++);
set_version_unlocked(type, next_version_tag);
assert (type->tp_version_tag <= _Py_MAX_GLOBAL_TYPE_VERSION_TAG);
}
else {
@ -9007,7 +9020,11 @@ type_ready_set_new(PyTypeObject *type, int initial)
&& base == &PyBaseObject_Type
&& !(type->tp_flags & Py_TPFLAGS_HEAPTYPE))
{
type_add_flags(type, Py_TPFLAGS_DISALLOW_INSTANTIATION);
if (initial) {
type_add_flags(type, Py_TPFLAGS_DISALLOW_INSTANTIATION);
} else {
assert(type->tp_flags & Py_TPFLAGS_DISALLOW_INSTANTIATION);
}
}
if (!(type->tp_flags & Py_TPFLAGS_DISALLOW_INSTANTIATION)) {
@ -9021,13 +9038,17 @@ type_ready_set_new(PyTypeObject *type, int initial)
}
}
else {
// tp_new is NULL: inherit tp_new from base
type->tp_new = base->tp_new;
if (initial) {
// tp_new is NULL: inherit tp_new from base
type->tp_new = base->tp_new;
}
}
}
else {
// Py_TPFLAGS_DISALLOW_INSTANTIATION sets tp_new to NULL
type->tp_new = NULL;
if (initial) {
type->tp_new = NULL;
}
}
return 0;
}
@ -9160,7 +9181,12 @@ type_ready(PyTypeObject *type, int initial)
}
/* All done -- set the ready flag */
type_add_flags(type, Py_TPFLAGS_READY);
if (initial) {
type_add_flags(type, Py_TPFLAGS_READY);
} else {
assert(type->tp_flags & Py_TPFLAGS_READY);
}
stop_readying(type);
assert(_PyType_CheckConsistency(type));
@ -9209,15 +9235,16 @@ init_static_type(PyInterpreterState *interp, PyTypeObject *self,
assert(!(self->tp_flags & Py_TPFLAGS_MANAGED_DICT));
assert(!(self->tp_flags & Py_TPFLAGS_MANAGED_WEAKREF));
if ((self->tp_flags & Py_TPFLAGS_READY) == 0) {
assert(initial);
if (initial) {
assert((self->tp_flags & Py_TPFLAGS_READY) == 0);
type_add_flags(self, _Py_TPFLAGS_STATIC_BUILTIN);
type_add_flags(self, Py_TPFLAGS_IMMUTABLETYPE);
assert(NEXT_GLOBAL_VERSION_TAG <= _Py_MAX_GLOBAL_TYPE_VERSION_TAG);
if (self->tp_version_tag == 0) {
_PyType_SetVersion(self, NEXT_GLOBAL_VERSION_TAG++);
unsigned int next_version_tag = next_global_version_tag();
assert(next_version_tag != 0);
_PyType_SetVersion(self, next_version_tag);
}
}
else {