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gh-117323: Make `cell` thread-safe in free-threaded builds (#117330) 

Use critical sections to lock around accesses to cell contents. The critical sections are no-ops in the default (with GIL) build.
This commit is contained in:
Sam Gross 2024-03-29 13:35:43 -04:00 committed by GitHub
parent 397d88db5e
commit 19c1dd60c5
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
11 changed files with 83 additions and 43 deletions
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48
Include/internal/pycore_cell.h Normal file
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@ -0,0 +1,48 @@
#ifndef Py_INTERNAL_CELL_H
#define Py_INTERNAL_CELL_H
#include "pycore_critical_section.h"
#ifdef __cplusplus
extern "C" {
#endif
#ifndef Py_BUILD_CORE
# error "this header requires Py_BUILD_CORE define"
#endif
// Sets the cell contents to `value` and return previous contents. Steals a
// reference to `value`.
static inline PyObject *
PyCell_SwapTakeRef(PyCellObject *cell, PyObject *value)
{
PyObject *old_value;
Py_BEGIN_CRITICAL_SECTION(cell);
old_value = cell->ob_ref;
cell->ob_ref = value;
Py_END_CRITICAL_SECTION();
return old_value;
}
static inline void
PyCell_SetTakeRef(PyCellObject *cell, PyObject *value)
{
PyObject *old_value = PyCell_SwapTakeRef(cell, value);
Py_XDECREF(old_value);
}
// Gets the cell contents. Returns a new reference.
static inline PyObject *
PyCell_GetRef(PyCellObject *cell)
{
PyObject *res;
Py_BEGIN_CRITICAL_SECTION(cell);
res = Py_XNewRef(cell->ob_ref);
Py_END_CRITICAL_SECTION();
return res;
}
#ifdef __cplusplus
}
#endif
#endif /* !Py_INTERNAL_CELL_H */

1
Makefile.pre.in
View File

@ -1130,6 +1130,7 @@ PYTHON_HEADERS= \
$(srcdir)/Include/internal/pycore_bytesobject.h \
$(srcdir)/Include/internal/pycore_call.h \
$(srcdir)/Include/internal/pycore_capsule.h \
$(srcdir)/Include/internal/pycore_cell.h \
$(srcdir)/Include/internal/pycore_ceval.h \
$(srcdir)/Include/internal/pycore_ceval_state.h \
$(srcdir)/Include/internal/pycore_code.h \

8
Objects/cellobject.c
View File

@ -1,6 +1,7 @@
/* Cell object implementation */
#include "Python.h"
#include "pycore_cell.h" // PyCell_GetRef()
#include "pycore_modsupport.h" // _PyArg_NoKeywords()
#include "pycore_object.h"
@ -56,8 +57,7 @@ PyCell_Get(PyObject *op)
PyErr_BadInternalCall();
return NULL;
}
PyObject *value = PyCell_GET(op);
return Py_XNewRef(value);
return PyCell_GetRef((PyCellObject *)op);
}
int
@ -67,9 +67,7 @@ PyCell_Set(PyObject *op, PyObject *value)
PyErr_BadInternalCall();
return -1;
}
PyObject *old_value = PyCell_GET(op);
PyCell_SET(op, Py_XNewRef(value));
Py_XDECREF(old_value);
PyCell_SetTakeRef((PyCellObject *)op, Py_XNewRef(value));
return 0;
}

1
PCbuild/pythoncore.vcxproj
View File

@ -210,6 +210,7 @@
<ClInclude Include="..\Include\internal\pycore_bytesobject.h" />
<ClInclude Include="..\Include\internal\pycore_call.h" />
<ClInclude Include="..\Include\internal\pycore_capsule.h" />
<ClInclude Include="..\Include\internal\pycore_cell.h" />
<ClInclude Include="..\Include\internal\pycore_ceval.h" />
<ClInclude Include="..\Include\internal\pycore_ceval_state.h" />
<ClInclude Include="..\Include\internal\pycore_cfg.h" />

3
PCbuild/pythoncore.vcxproj.filters
View File

@ -555,6 +555,9 @@
<ClInclude Include="..\Include\internal\pycore_capsule.h">
<Filter>Include\internal</Filter>
</ClInclude>
<ClInclude Include="..\Include\internal\pycore_cell.h">
<Filter>Include\internal</Filter>
</ClInclude>
<ClInclude Include="..\Include\internal\pycore_ceval.h">
<Filter>Include\internal</Filter>
</ClInclude>

20
Python/bytecodes.c
View File

@ -8,6 +8,7 @@
#include "Python.h"
#include "pycore_abstract.h" // _PyIndex_Check()
#include "pycore_cell.h" // PyCell_GetRef()
#include "pycore_code.h"
#include "pycore_emscripten_signal.h" // _Py_CHECK_EMSCRIPTEN_SIGNALS
#include "pycore_function.h"
@ -1523,14 +1524,13 @@ dummy_func(
inst(DELETE_DEREF, (--)) {
PyObject *cell = GETLOCAL(oparg);
PyObject *oldobj = PyCell_GET(cell);
// Can't use ERROR_IF here.
// Fortunately we don't need its superpower.
PyObject *oldobj = PyCell_SwapTakeRef((PyCellObject *)cell, NULL);
if (oldobj == NULL) {
_PyEval_FormatExcUnbound(tstate, _PyFrame_GetCode(frame), oparg);
ERROR_NO_POP();
}
PyCell_SET(cell, NULL);
Py_DECREF(oldobj);
}
@ -1543,32 +1543,28 @@ dummy_func(
ERROR_NO_POP();
}
if (!value) {
PyObject *cell = GETLOCAL(oparg);
value = PyCell_GET(cell);
PyCellObject *cell = (PyCellObject *)GETLOCAL(oparg);
value = PyCell_GetRef(cell);
if (value == NULL) {
_PyEval_FormatExcUnbound(tstate, _PyFrame_GetCode(frame), oparg);
ERROR_NO_POP();
}
Py_INCREF(value);
}
Py_DECREF(class_dict);
}
inst(LOAD_DEREF, ( -- value)) {
PyObject *cell = GETLOCAL(oparg);
value = PyCell_GET(cell);
PyCellObject *cell = (PyCellObject *)GETLOCAL(oparg);
value = PyCell_GetRef(cell);
if (value == NULL) {
_PyEval_FormatExcUnbound(tstate, _PyFrame_GetCode(frame), oparg);
ERROR_IF(true, error);
}
Py_INCREF(value);
}
inst(STORE_DEREF, (v --)) {
PyObject *cell = GETLOCAL(oparg);
PyObject *oldobj = PyCell_GET(cell);
PyCell_SET(cell, v);
Py_XDECREF(oldobj);
PyCellObject *cell = (PyCellObject *)GETLOCAL(oparg);
PyCell_SetTakeRef(cell, v);
}
inst(COPY_FREE_VARS, (--)) {

1
Python/ceval.c
View File

@ -5,6 +5,7 @@
#include "Python.h"
#include "pycore_abstract.h" // _PyIndex_Check()
#include "pycore_call.h" // _PyObject_CallNoArgs()
#include "pycore_cell.h" // PyCell_GetRef()
#include "pycore_ceval.h"
#include "pycore_code.h"
#include "pycore_emscripten_signal.h" // _Py_CHECK_EMSCRIPTEN_SIGNALS

19
Python/executor_cases.c.h generated
View File

@ -1362,14 +1362,13 @@
case _DELETE_DEREF: {
oparg = CURRENT_OPARG();
PyObject *cell = GETLOCAL(oparg);
PyObject *oldobj = PyCell_GET(cell);
// Can't use ERROR_IF here.
// Fortunately we don't need its superpower.
PyObject *oldobj = PyCell_SwapTakeRef((PyCellObject *)cell, NULL);
if (oldobj == NULL) {
_PyEval_FormatExcUnbound(tstate, _PyFrame_GetCode(frame), oparg);
JUMP_TO_ERROR();
}
PyCell_SET(cell, NULL);
Py_DECREF(oldobj);
break;
}
@ -1387,13 +1386,12 @@
JUMP_TO_ERROR();
}
if (!value) {
PyObject *cell = GETLOCAL(oparg);
value = PyCell_GET(cell);
PyCellObject *cell = (PyCellObject *)GETLOCAL(oparg);
value = PyCell_GetRef(cell);
if (value == NULL) {
_PyEval_FormatExcUnbound(tstate, _PyFrame_GetCode(frame), oparg);
JUMP_TO_ERROR();
}
Py_INCREF(value);
}
Py_DECREF(class_dict);
stack_pointer[-1] = value;
@ -1403,13 +1401,12 @@
case _LOAD_DEREF: {
PyObject *value;
oparg = CURRENT_OPARG();
PyObject *cell = GETLOCAL(oparg);
value = PyCell_GET(cell);
PyCellObject *cell = (PyCellObject *)GETLOCAL(oparg);
value = PyCell_GetRef(cell);
if (value == NULL) {
_PyEval_FormatExcUnbound(tstate, _PyFrame_GetCode(frame), oparg);
if (true) JUMP_TO_ERROR();
}
Py_INCREF(value);
stack_pointer[0] = value;
stack_pointer += 1;
break;
@ -1419,10 +1416,8 @@
PyObject *v;
oparg = CURRENT_OPARG();
v = stack_pointer[-1];
PyObject *cell = GETLOCAL(oparg);
PyObject *oldobj = PyCell_GET(cell);
PyCell_SET(cell, v);
Py_XDECREF(oldobj);
PyCellObject *cell = (PyCellObject *)GETLOCAL(oparg);
PyCell_SetTakeRef(cell, v);
stack_pointer += -1;
break;
}

19
Python/generated_cases.c.h generated
View File

@ -2320,14 +2320,13 @@
next_instr += 1;
INSTRUCTION_STATS(DELETE_DEREF);
PyObject *cell = GETLOCAL(oparg);
PyObject *oldobj = PyCell_GET(cell);
// Can't use ERROR_IF here.
// Fortunately we don't need its superpower.
PyObject *oldobj = PyCell_SwapTakeRef((PyCellObject *)cell, NULL);
if (oldobj == NULL) {
_PyEval_FormatExcUnbound(tstate, _PyFrame_GetCode(frame), oparg);
goto error;
}
PyCell_SET(cell, NULL);
Py_DECREF(oldobj);
DISPATCH();
}
@ -4096,13 +4095,12 @@
next_instr += 1;
INSTRUCTION_STATS(LOAD_DEREF);
PyObject *value;
PyObject *cell = GETLOCAL(oparg);
value = PyCell_GET(cell);
PyCellObject *cell = (PyCellObject *)GETLOCAL(oparg);
value = PyCell_GetRef(cell);
if (value == NULL) {
_PyEval_FormatExcUnbound(tstate, _PyFrame_GetCode(frame), oparg);
if (true) goto error;
}
Py_INCREF(value);
stack_pointer[0] = value;
stack_pointer += 1;
DISPATCH();
@ -4186,13 +4184,12 @@
goto error;
}
if (!value) {
PyObject *cell = GETLOCAL(oparg);
value = PyCell_GET(cell);
PyCellObject *cell = (PyCellObject *)GETLOCAL(oparg);
value = PyCell_GetRef(cell);
if (value == NULL) {
_PyEval_FormatExcUnbound(tstate, _PyFrame_GetCode(frame), oparg);
goto error;
}
Py_INCREF(value);
}
Py_DECREF(class_dict);
stack_pointer[-1] = value;
@ -5436,10 +5433,8 @@
INSTRUCTION_STATS(STORE_DEREF);
PyObject *v;
v = stack_pointer[-1];
PyObject *cell = GETLOCAL(oparg);
PyObject *oldobj = PyCell_GET(cell);
PyCell_SET(cell, v);
Py_XDECREF(oldobj);
PyCellObject *cell = (PyCellObject *)GETLOCAL(oparg);
PyCell_SetTakeRef(cell, v);
stack_pointer += -1;
DISPATCH();
}

5
Tools/cases_generator/analyzer.py
View File

@ -520,8 +520,9 @@ def effect_depends_on_oparg_1(op: parser.InstDef) -> bool:
def compute_properties(op: parser.InstDef) -> Properties:
has_free = (
variable_used(op, "PyCell_New")
or variable_used(op, "PyCell_GET")
or variable_used(op, "PyCell_SET")
or variable_used(op, "PyCell_GetRef")
or variable_used(op, "PyCell_SetTakeRef")
or variable_used(op, "PyCell_SwapTakeRef")
)
deopts_if = variable_used(op, "DEOPT_IF")
exits_if = variable_used(op, "EXIT_IF")

1
Tools/jit/template.c
View File

@ -2,6 +2,7 @@
#include "pycore_call.h"
#include "pycore_ceval.h"
#include "pycore_cell.h"
#include "pycore_dict.h"
#include "pycore_emscripten_signal.h"
#include "pycore_intrinsics.h"