pystate: use stop-the-world in a few places

 - _PyThread_CurrentExceptions
 - _PyThread_CurrentFrames

Author: colesbury

Python/ceval.c

@@ -2707,9 +2707,7 @@ PyEval_SetTraceAllThreads(Py_tracefunc func, PyObject *arg)
 
     _PyObjectQueue *queue = NULL;
 
-    _PyMutex_lock(&_PyRuntime.stoptheworld_mutex);
     _PyRuntimeState_StopTheWorld(&_PyRuntime);
-
     HEAD_LOCK(runtime);
     PyThreadState* ts = PyInterpreterState_ThreadHead(interp);
     while (ts) {
@@ -2720,9 +2718,7 @@ PyEval_SetTraceAllThreads(Py_tracefunc func, PyObject *arg)
         ts = PyThreadState_Next(ts);
     }
     HEAD_UNLOCK(runtime);
-
     _PyRuntimeState_StartTheWorld(&_PyRuntime);
-    _PyMutex_unlock(&_PyRuntime.stoptheworld_mutex);
 
     PyObject *old_traceobj;
     _PyObjectQueue_ForEach(&queue, old_traceobj) {

Python/pystate.c

@@ -1764,6 +1764,7 @@ _PyThread_CurrentFrames(void)
      * need to grab head_mutex for the duration.
      */
     _PyRuntimeState *runtime = tstate->interp->runtime;
+    _PyRuntimeState_StopTheWorld(runtime);
     HEAD_LOCK(runtime);
     PyInterpreterState *i;
     for (i = runtime->interpreters.head; i != NULL; i = i->next) {
@@ -1797,6 +1798,7 @@ _PyThread_CurrentFrames(void)
 
 done:
     HEAD_UNLOCK(runtime);
+    _PyRuntimeState_StartTheWorld(runtime);
     return result;
 }
 
@@ -1823,6 +1825,7 @@ _PyThread_CurrentExceptions(void)
      * need to grab head_mutex for the duration.
      */
     _PyRuntimeState *runtime = tstate->interp->runtime;
+    _PyRuntimeState_StopTheWorld(runtime);
     HEAD_LOCK(runtime);
     PyInterpreterState *i;
     for (i = runtime->interpreters.head; i != NULL; i = i->next) {
@@ -1856,6 +1859,7 @@ _PyThread_CurrentExceptions(void)
 
 done:
     HEAD_UNLOCK(runtime);
+    _PyRuntimeState_StartTheWorld(runtime);
     return result;
 }