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bpo-40082: trip_signal() uses the main interpreter (GH-19441) 

Fix the signal handler: it now always uses the main interpreter,
rather than trying to get the current Python thread state.

The following function now accepts an interpreter, instead of a
Python thread state:

* _PyEval_SignalReceived()
* _Py_ThreadCanHandleSignals()
* _PyEval_AddPendingCall()
* COMPUTE_EVAL_BREAKER()
* SET_GIL_DROP_REQUEST(), RESET_GIL_DROP_REQUEST()
* SIGNAL_PENDING_CALLS(), UNSIGNAL_PENDING_CALLS()
* SIGNAL_PENDING_SIGNALS(), UNSIGNAL_PENDING_SIGNALS()
* SIGNAL_ASYNC_EXC(), UNSIGNAL_ASYNC_EXC()

Py_AddPendingCall() now uses the main interpreter if it fails to the
current Python thread state.

Convert _PyThreadState_GET() and PyInterpreterState_GET_UNSAFE()
macros to static inline functions.
This commit is contained in:
Victor Stinner 2020-04-08 23:35:05 +02:00 committed by GitHub
parent cfc3c2f8b3
commit b54a99d643
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
6 changed files with 94 additions and 85 deletions
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4
Include/internal/pycore_ceval.h
View File

@ -19,9 +19,9 @@ extern void _Py_FinishPendingCalls(PyThreadState *tstate);
extern void _PyEval_InitRuntimeState(struct _ceval_runtime_state *);
extern int _PyEval_InitState(struct _ceval_state *ceval);
extern void _PyEval_FiniState(struct _ceval_state *ceval);
PyAPI_FUNC(void) _PyEval_SignalReceived(PyThreadState *tstate);
PyAPI_FUNC(void) _PyEval_SignalReceived(PyInterpreterState *interp);
PyAPI_FUNC(int) _PyEval_AddPendingCall(
PyThreadState *tstate,
PyInterpreterState *interp,
int (*func)(void *),
void *arg);
PyAPI_FUNC(void) _PyEval_SignalAsyncExc(PyThreadState *tstate);

13
Include/internal/pycore_pystate.h
View File

@ -310,9 +310,9 @@ _Py_IsMainInterpreter(PyThreadState* tstate)
/* Only handle signals on the main thread of the main interpreter. */
static inline int
_Py_ThreadCanHandleSignals(PyThreadState *tstate)
_Py_ThreadCanHandleSignals(PyInterpreterState *interp)
{
return (_Py_IsMainThread() && _Py_IsMainInterpreter(tstate));
return (_Py_IsMainThread() && interp == _PyRuntime.interpreters.main);
}
@ -340,7 +340,9 @@ static inline PyThreadState* _PyRuntimeState_GetThreadState(_PyRuntimeState *run
The caller must hold the GIL.
See also PyThreadState_Get() and PyThreadState_GET(). */
#define _PyThreadState_GET() _PyRuntimeState_GetThreadState(&_PyRuntime)
static inline PyThreadState *_PyThreadState_GET(void) {
return _PyRuntimeState_GetThreadState(&_PyRuntime);
}
/* Redefine PyThreadState_GET() as an alias to _PyThreadState_GET() */
#undef PyThreadState_GET
@ -354,7 +356,10 @@ static inline PyThreadState* _PyRuntimeState_GetThreadState(_PyRuntimeState *run
See also _PyInterpreterState_Get()
and _PyGILState_GetInterpreterStateUnsafe(). */
#define _PyInterpreterState_GET_UNSAFE() (_PyThreadState_GET()->interp)
static inline PyInterpreterState* _PyInterpreterState_GET_UNSAFE(void) {
PyThreadState *tstate = _PyThreadState_GET();
return tstate->interp;
}
/* Other */

2
Misc/NEWS.d/next/Core and Builtins/2020-04-08-22-33-24.bpo-40082.WI3-lu.rst Normal file
View File

@ -0,0 +1,2 @@
Fix the signal handler: it now always uses the main interpreter, rather than
trying to get the current Python thread state.

27
Modules/signalmodule.c
View File

@ -252,14 +252,11 @@ trip_signal(int sig_num)
cleared in PyErr_CheckSignals() before .tripped. */
_Py_atomic_store(&is_tripped, 1);
/* Get the Python thread state using PyGILState API, since
_PyThreadState_GET() returns NULL if the GIL is released.
For example, signal.raise_signal() releases the GIL. */
PyThreadState *tstate = PyGILState_GetThisThreadState();
assert(tstate != NULL);
/* Signals are always handled by the main interpreter */
PyInterpreterState *interp = _PyRuntime.interpreters.main;
/* Notify ceval.c */
_PyEval_SignalReceived(tstate);
_PyEval_SignalReceived(interp);
/* And then write to the wakeup fd *after* setting all the globals and
doing the _PyEval_SignalReceived. We used to write to the wakeup fd
@ -299,7 +296,7 @@ trip_signal(int sig_num)
{
/* _PyEval_AddPendingCall() isn't signal-safe, but we
still use it for this exceptional case. */
_PyEval_AddPendingCall(tstate,
_PyEval_AddPendingCall(interp,
report_wakeup_send_error,
(void *)(intptr_t) last_error);
}
@ -318,7 +315,7 @@ trip_signal(int sig_num)
{
/* _PyEval_AddPendingCall() isn't signal-safe, but we
still use it for this exceptional case. */
_PyEval_AddPendingCall(tstate,
_PyEval_AddPendingCall(interp,
report_wakeup_write_error,
(void *)(intptr_t)errno);
}
@ -476,7 +473,7 @@ signal_signal_impl(PyObject *module, int signalnum, PyObject *handler)
#endif
PyThreadState *tstate = _PyThreadState_GET();
if (!_Py_ThreadCanHandleSignals(tstate)) {
if (!_Py_ThreadCanHandleSignals(tstate->interp)) {
_PyErr_SetString(tstate, PyExc_ValueError,
"signal only works in main thread "
"of the main interpreter");
@ -704,7 +701,7 @@ signal_set_wakeup_fd(PyObject *self, PyObject *args, PyObject *kwds)
#endif
PyThreadState *tstate = _PyThreadState_GET();
if (!_Py_ThreadCanHandleSignals(tstate)) {
if (!_Py_ThreadCanHandleSignals(tstate->interp)) {
_PyErr_SetString(tstate, PyExc_ValueError,
"set_wakeup_fd only works in main thread "
"of the main interpreter");
@ -1681,7 +1678,7 @@ int
PyErr_CheckSignals(void)
{
PyThreadState *tstate = _PyThreadState_GET();
if (!_Py_ThreadCanHandleSignals(tstate)) {
if (!_Py_ThreadCanHandleSignals(tstate->interp)) {
return 0;
}
@ -1787,8 +1784,8 @@ PyOS_FiniInterrupts(void)
int
PyOS_InterruptOccurred(void)
{
PyThreadState *tstate = _PyThreadState_GET();
if (!_Py_ThreadCanHandleSignals(tstate)) {
PyInterpreterState *interp = _PyInterpreterState_GET_UNSAFE();
if (!_Py_ThreadCanHandleSignals(interp)) {
return 0;
}
@ -1824,8 +1821,8 @@ _PySignal_AfterFork(void)
int
_PyOS_IsMainThread(void)
{
PyThreadState *tstate = _PyThreadState_GET();
return _Py_ThreadCanHandleSignals(tstate);
PyInterpreterState *interp = _PyInterpreterState_GET_UNSAFE();
return _Py_ThreadCanHandleSignals(interp);
}
#ifdef MS_WINDOWS

117
Python/ceval.c
View File

@ -142,15 +142,14 @@ is_tstate_valid(PyThreadState *tstate)
1. We believe this is all right because the eval loop will release
the GIL eventually anyway. */
static inline void
COMPUTE_EVAL_BREAKER(PyThreadState *tstate,
COMPUTE_EVAL_BREAKER(PyInterpreterState *interp,
struct _ceval_runtime_state *ceval,
struct _ceval_state *ceval2)
{
assert(is_tstate_valid(tstate));
_Py_atomic_store_relaxed(&ceval2->eval_breaker,
_Py_atomic_load_relaxed(&ceval->gil_drop_request)
| (_Py_atomic_load_relaxed(&ceval->signals_pending)
&& _Py_ThreadCanHandleSignals(tstate))
&& _Py_ThreadCanHandleSignals(interp))
| (_Py_atomic_load_relaxed(&ceval2->pending.calls_to_do)
&& _Py_ThreadCanHandlePendingCalls())
| ceval2->pending.async_exc);
@ -158,90 +157,82 @@ COMPUTE_EVAL_BREAKER(PyThreadState *tstate,
static inline void
SET_GIL_DROP_REQUEST(PyThreadState *tstate)
SET_GIL_DROP_REQUEST(PyInterpreterState *interp)
{
assert(is_tstate_valid(tstate));
struct _ceval_runtime_state *ceval = &tstate->interp->runtime->ceval;
struct _ceval_state *ceval2 = &tstate->interp->ceval;
struct _ceval_runtime_state *ceval = &interp->runtime->ceval;
struct _ceval_state *ceval2 = &interp->ceval;
_Py_atomic_store_relaxed(&ceval->gil_drop_request, 1);
_Py_atomic_store_relaxed(&ceval2->eval_breaker, 1);
}
static inline void
RESET_GIL_DROP_REQUEST(PyThreadState *tstate)
RESET_GIL_DROP_REQUEST(PyInterpreterState *interp)
{
assert(is_tstate_valid(tstate));
struct _ceval_runtime_state *ceval = &tstate->interp->runtime->ceval;
struct _ceval_state *ceval2 = &tstate->interp->ceval;
struct _ceval_runtime_state *ceval = &interp->runtime->ceval;
struct _ceval_state *ceval2 = &interp->ceval;
_Py_atomic_store_relaxed(&ceval->gil_drop_request, 0);
COMPUTE_EVAL_BREAKER(tstate, ceval, ceval2);
COMPUTE_EVAL_BREAKER(interp, ceval, ceval2);
}
static inline void
SIGNAL_PENDING_CALLS(PyThreadState *tstate)
SIGNAL_PENDING_CALLS(PyInterpreterState *interp)
{
assert(is_tstate_valid(tstate));
struct _ceval_runtime_state *ceval = &tstate->interp->runtime->ceval;
struct _ceval_state *ceval2 = &tstate->interp->ceval;
struct _ceval_runtime_state *ceval = &interp->runtime->ceval;
struct _ceval_state *ceval2 = &interp->ceval;
_Py_atomic_store_relaxed(&ceval2->pending.calls_to_do, 1);
COMPUTE_EVAL_BREAKER(tstate, ceval, ceval2);
COMPUTE_EVAL_BREAKER(interp, ceval, ceval2);
}
static inline void
UNSIGNAL_PENDING_CALLS(PyThreadState *tstate)
UNSIGNAL_PENDING_CALLS(PyInterpreterState *interp)
{
assert(is_tstate_valid(tstate));
struct _ceval_runtime_state *ceval = &tstate->interp->runtime->ceval;
struct _ceval_state *ceval2 = &tstate->interp->ceval;
struct _ceval_runtime_state *ceval = &interp->runtime->ceval;
struct _ceval_state *ceval2 = &interp->ceval;
_Py_atomic_store_relaxed(&ceval2->pending.calls_to_do, 0);
COMPUTE_EVAL_BREAKER(tstate, ceval, ceval2);
COMPUTE_EVAL_BREAKER(interp, ceval, ceval2);
}
static inline void
SIGNAL_PENDING_SIGNALS(PyThreadState *tstate)
SIGNAL_PENDING_SIGNALS(PyInterpreterState *interp)
{
assert(is_tstate_valid(tstate));
struct _ceval_runtime_state *ceval = &tstate->interp->runtime->ceval;
struct _ceval_state *ceval2 = &tstate->interp->ceval;
struct _ceval_runtime_state *ceval = &interp->runtime->ceval;
struct _ceval_state *ceval2 = &interp->ceval;
_Py_atomic_store_relaxed(&ceval->signals_pending, 1);
/* eval_breaker is not set to 1 if thread_can_handle_signals() is false */
COMPUTE_EVAL_BREAKER(tstate, ceval, ceval2);
COMPUTE_EVAL_BREAKER(interp, ceval, ceval2);
}
static inline void
UNSIGNAL_PENDING_SIGNALS(PyThreadState *tstate)
UNSIGNAL_PENDING_SIGNALS(PyInterpreterState *interp)
{
assert(is_tstate_valid(tstate));
struct _ceval_runtime_state *ceval = &tstate->interp->runtime->ceval;
struct _ceval_state *ceval2 = &tstate->interp->ceval;
struct _ceval_runtime_state *ceval = &interp->runtime->ceval;
struct _ceval_state *ceval2 = &interp->ceval;
_Py_atomic_store_relaxed(&ceval->signals_pending, 0);
COMPUTE_EVAL_BREAKER(tstate, ceval, ceval2);
COMPUTE_EVAL_BREAKER(interp, ceval, ceval2);
}
static inline void
SIGNAL_ASYNC_EXC(PyThreadState *tstate)
SIGNAL_ASYNC_EXC(PyInterpreterState *interp)
{
assert(is_tstate_valid(tstate));
struct _ceval_state *ceval2 = &tstate->interp->ceval;
struct _ceval_state *ceval2 = &interp->ceval;
ceval2->pending.async_exc = 1;
_Py_atomic_store_relaxed(&ceval2->eval_breaker, 1);
}
static inline void
UNSIGNAL_ASYNC_EXC(PyThreadState *tstate)
UNSIGNAL_ASYNC_EXC(PyInterpreterState *interp)
{
assert(is_tstate_valid(tstate));
struct _ceval_runtime_state *ceval = &tstate->interp->runtime->ceval;
struct _ceval_state *ceval2 = &tstate->interp->ceval;
struct _ceval_runtime_state *ceval = &interp->runtime->ceval;
struct _ceval_state *ceval2 = &interp->ceval;
ceval2->pending.async_exc = 0;
COMPUTE_EVAL_BREAKER(tstate, ceval, ceval2);
COMPUTE_EVAL_BREAKER(interp, ceval, ceval2);
}
@ -440,7 +431,8 @@ _PyEval_ReInitThreads(_PyRuntimeState *runtime)
void
_PyEval_SignalAsyncExc(PyThreadState *tstate)
{
SIGNAL_ASYNC_EXC(tstate);
assert(is_tstate_valid(tstate));
SIGNAL_ASYNC_EXC(tstate->interp);
}
PyThreadState *
@ -492,12 +484,12 @@ PyEval_RestoreThread(PyThreadState *tstate)
*/
void
_PyEval_SignalReceived(PyThreadState *tstate)
_PyEval_SignalReceived(PyInterpreterState *interp)
{
/* bpo-30703: Function called when the C signal handler of Python gets a
signal. We cannot queue a callback using _PyEval_AddPendingCall() since
that function is not async-signal-safe. */
SIGNAL_PENDING_SIGNALS(tstate);
SIGNAL_PENDING_SIGNALS(interp);
}
/* Push one item onto the queue while holding the lock. */
@ -537,10 +529,10 @@ _pop_pending_call(struct _pending_calls *pending,
*/
int
_PyEval_AddPendingCall(PyThreadState *tstate,
_PyEval_AddPendingCall(PyInterpreterState *interp,
int (*func)(void *), void *arg)
{
struct _pending_calls *pending = &tstate->interp->ceval.pending;
struct _pending_calls *pending = &interp->ceval.pending;
/* Ensure that _PyEval_InitPendingCalls() was called
and that _PyEval_FiniPendingCalls() is not called yet. */
@ -551,7 +543,7 @@ _PyEval_AddPendingCall(PyThreadState *tstate,
PyThread_release_lock(pending->lock);
/* signal main loop */
SIGNAL_PENDING_CALLS(tstate);
SIGNAL_PENDING_CALLS(interp);
return result;
}
@ -574,24 +566,30 @@ Py_AddPendingCall(int (*func)(void *), void *arg)
if (tstate == NULL) {
tstate = PyGILState_GetThisThreadState();
}
/* tstate can be NULL if Py_AddPendingCall() is called in a thread
which is no Python thread state. Fail with a fatal error in this
case. */
ensure_tstate_not_null(__func__, tstate);
return _PyEval_AddPendingCall(tstate, func, arg);
PyInterpreterState *interp;
if (tstate != NULL) {
interp = tstate->interp;
}
else {
/* Last resort: use the main interpreter */
interp = _PyRuntime.interpreters.main;
}
return _PyEval_AddPendingCall(interp, func, arg);
}
static int
handle_signals(PyThreadState *tstate)
{
if (!_Py_ThreadCanHandleSignals(tstate)) {
assert(is_tstate_valid(tstate));
if (!_Py_ThreadCanHandleSignals(tstate->interp)) {
return 0;
}
UNSIGNAL_PENDING_SIGNALS(tstate);
UNSIGNAL_PENDING_SIGNALS(tstate->interp);
if (_PyErr_CheckSignalsTstate(tstate) < 0) {
/* On failure, re-schedule a call to handle_signals(). */
SIGNAL_PENDING_SIGNALS(tstate);
SIGNAL_PENDING_SIGNALS(tstate->interp);
return -1;
}
return 0;
@ -600,6 +598,8 @@ handle_signals(PyThreadState *tstate)
static int
make_pending_calls(PyThreadState *tstate)
{
assert(is_tstate_valid(tstate));
/* only execute pending calls on main thread */
if (!_Py_ThreadCanHandlePendingCalls()) {
return 0;
@ -614,7 +614,7 @@ make_pending_calls(PyThreadState *tstate)
/* unsignal before starting to call callbacks, so that any callback
added in-between re-signals */
UNSIGNAL_PENDING_CALLS(tstate);
UNSIGNAL_PENDING_CALLS(tstate->interp);
int res = 0;
/* perform a bounded number of calls, in case of recursion */
@ -643,7 +643,7 @@ make_pending_calls(PyThreadState *tstate)
error:
busy = 0;
SIGNAL_PENDING_CALLS(tstate);
SIGNAL_PENDING_CALLS(tstate->interp);
return res;
}
@ -828,9 +828,10 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
static int
eval_frame_handle_pending(PyThreadState *tstate)
{
/* Pending signals */
_PyRuntimeState * const runtime = &_PyRuntime;
struct _ceval_runtime_state *ceval = &runtime->ceval;
/* Pending signals */
if (_Py_atomic_load_relaxed(&ceval->signals_pending)) {
if (handle_signals(tstate) != 0) {
return -1;
@ -866,7 +867,7 @@ eval_frame_handle_pending(PyThreadState *tstate)
if (tstate->async_exc != NULL) {
PyObject *exc = tstate->async_exc;
tstate->async_exc = NULL;
UNSIGNAL_ASYNC_EXC(tstate);
UNSIGNAL_ASYNC_EXC(tstate->interp);
_PyErr_SetNone(tstate, exc);
Py_DECREF(exc);
return -1;

16
Python/ceval_gil.h
View File

@ -168,7 +168,8 @@ drop_gil(struct _ceval_runtime_state *ceval, PyThreadState *tstate)
/* Not switched yet => wait */
if (((PyThreadState*)_Py_atomic_load_relaxed(&gil->last_holder)) == tstate)
{
RESET_GIL_DROP_REQUEST(tstate);
assert(is_tstate_valid(tstate));
RESET_GIL_DROP_REQUEST(tstate->interp);
/* NOTE: if COND_WAIT does not atomically start waiting when
releasing the mutex, another thread can run through, take
the GIL and drop it again, and reset the condition
@ -223,7 +224,8 @@ take_gil(PyThreadState *tstate)
}
assert(is_tstate_valid(tstate));
struct _ceval_runtime_state *ceval = &tstate->interp->runtime->ceval;
PyInterpreterState *interp = tstate->interp;
struct _ceval_runtime_state *ceval = &interp->runtime->ceval;
struct _gil_runtime_state *gil = &ceval->gil;
/* Check that _PyEval_InitThreads() was called to create the lock */
@ -252,8 +254,9 @@ take_gil(PyThreadState *tstate)
MUTEX_UNLOCK(gil->mutex);
PyThread_exit_thread();
}
assert(is_tstate_valid(tstate));
SET_GIL_DROP_REQUEST(tstate);
SET_GIL_DROP_REQUEST(interp);
}
}
@ -289,9 +292,10 @@ _ready:
drop_gil(ceval, tstate);
PyThread_exit_thread();
}
assert(is_tstate_valid(tstate));
if (_Py_atomic_load_relaxed(&ceval->gil_drop_request)) {
RESET_GIL_DROP_REQUEST(tstate);
RESET_GIL_DROP_REQUEST(interp);
}
else {
/* bpo-40010: eval_breaker should be recomputed to be set to 1 if there
@ -299,8 +303,8 @@ _ready:
handle signals.
Note: RESET_GIL_DROP_REQUEST() calls COMPUTE_EVAL_BREAKER(). */
struct _ceval_state *ceval2 = &tstate->interp->ceval;
COMPUTE_EVAL_BREAKER(tstate, ceval, ceval2);
struct _ceval_state *ceval2 = &interp->ceval;
COMPUTE_EVAL_BREAKER(interp, ceval, ceval2);
}
/* Don't access tstate if the thread must exit */