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.
diff --git a/Include/internal/pycore_ceval.h b/Include/internal/pycore_ceval.h
index 1f96fc6..811aada 100644
--- a/Include/internal/pycore_ceval.h
+++ b/Include/internal/pycore_ceval.h
@@ -19,9 +19,9 @@
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);
diff --git a/Include/internal/pycore_pystate.h b/Include/internal/pycore_pystate.h
index fba0b6f..13a957a 100644
--- a/Include/internal/pycore_pystate.h
+++ b/Include/internal/pycore_pystate.h
@@ -310,9 +310,9 @@
/* 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 @@
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 @@
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 */
diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-04-08-22-33-24.bpo-40082.WI3-lu.rst b/Misc/NEWS.d/next/Core and Builtins/2020-04-08-22-33-24.bpo-40082.WI3-lu.rst
new file mode 100644
index 0000000..0a25b5e
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2020-04-08-22-33-24.bpo-40082.WI3-lu.rst
@@ -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.
diff --git a/Modules/signalmodule.c b/Modules/signalmodule.c
index 0a2c665..b089a80 100644
--- a/Modules/signalmodule.c
+++ b/Modules/signalmodule.c
@@ -252,14 +252,11 @@
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 @@
{
/* _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 @@
{
/* _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 @@
#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 @@
#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 @@
PyErr_CheckSignals(void)
{
PyThreadState *tstate = _PyThreadState_GET();
- if (!_Py_ThreadCanHandleSignals(tstate)) {
+ if (!_Py_ThreadCanHandleSignals(tstate->interp)) {
return 0;
}
@@ -1787,8 +1784,8 @@
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 @@
int
_PyOS_IsMainThread(void)
{
- PyThreadState *tstate = _PyThreadState_GET();
- return _Py_ThreadCanHandleSignals(tstate);
+ PyInterpreterState *interp = _PyInterpreterState_GET_UNSAFE();
+ return _Py_ThreadCanHandleSignals(interp);
}
#ifdef MS_WINDOWS
diff --git a/Python/ceval.c b/Python/ceval.c
index e219ef3..b712920 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -142,15 +142,14 @@
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 @@
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 @@
void
_PyEval_SignalAsyncExc(PyThreadState *tstate)
{
- SIGNAL_ASYNC_EXC(tstate);
+ assert(is_tstate_valid(tstate));
+ SIGNAL_ASYNC_EXC(tstate->interp);
}
PyThreadState *
@@ -492,12 +484,12 @@
*/
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 @@
*/
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 @@
PyThread_release_lock(pending->lock);
/* signal main loop */
- SIGNAL_PENDING_CALLS(tstate);
+ SIGNAL_PENDING_CALLS(interp);
return result;
}
@@ -574,24 +566,30 @@
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 @@
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 @@
/* 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 @@
error:
busy = 0;
- SIGNAL_PENDING_CALLS(tstate);
+ SIGNAL_PENDING_CALLS(tstate->interp);
return res;
}
@@ -828,9 +828,10 @@
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 @@
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;
diff --git a/Python/ceval_gil.h b/Python/ceval_gil.h
index b9e48a5..a025a9f 100644
--- a/Python/ceval_gil.h
+++ b/Python/ceval_gil.h
@@ -168,7 +168,8 @@
/* 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 @@
}
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 @@
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 @@
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 @@
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 */