bpo-45923: Decouple suspension of tracing from tracing flag. (GH-31908)

Include/internal/pycore_pystate.h

@@ -139,14 +139,9 @@ PyAPI_FUNC(void) _PyThreadState_DeleteExcept(
     _PyRuntimeState *runtime,
     PyThreadState *tstate);
 
-static inline void
-_PyThreadState_PauseTracing(PyThreadState *tstate)
-{
-    tstate->cframe->use_tracing = 0;
-}
 
 static inline void
-_PyThreadState_ResumeTracing(PyThreadState *tstate)
+_PyThreadState_UpdateTracingState(PyThreadState *tstate)
 {
     int use_tracing = (tstate->c_tracefunc != NULL
                        || tstate->c_profilefunc != NULL);

Python/ceval.c

@@ -5439,10 +5439,12 @@ handle_eval_breaker:
         }
 
 #if USE_COMPUTED_GOTOS
-        TARGET_DO_TRACING: {
+        TARGET_DO_TRACING:
 #else
-        case DO_TRACING: {
+        case DO_TRACING:
 #endif
+    {
+        if (tstate->tracing == 0) {
             int instr_prev = skip_backwards_over_extended_args(frame->f_code, frame->f_lasti);
             frame->f_lasti = INSTR_OFFSET();
             TRACING_NEXTOPARG();
@@ -5482,11 +5484,11 @@ handle_eval_breaker:
                     frame->stacktop = -1;
                 }
             }
-            TRACING_NEXTOPARG();
-            PRE_DISPATCH_GOTO();
-            DISPATCH_GOTO();
         }
-
+        TRACING_NEXTOPARG();
+        PRE_DISPATCH_GOTO();
+        DISPATCH_GOTO();
+    }
 
 #if USE_COMPUTED_GOTOS
         _unknown_opcode:
@@ -6673,27 +6675,38 @@ initialize_trace_info(PyTraceInfo *trace_info, _PyInterpreterFrame *frame)
     }
 }
 
+void
+PyThreadState_EnterTracing(PyThreadState *tstate)
+{
+    tstate->tracing++;
+}
+
+void
+PyThreadState_LeaveTracing(PyThreadState *tstate)
+{
+    tstate->tracing--;
+}
+
 static int
 call_trace(Py_tracefunc func, PyObject *obj,
            PyThreadState *tstate, _PyInterpreterFrame *frame,
            int what, PyObject *arg)
 {
     int result;
-    if (tstate->tracing)
+    if (tstate->tracing) {
         return 0;
-    tstate->tracing++;
-    _PyThreadState_PauseTracing(tstate);
+    }
     PyFrameObject *f = _PyFrame_GetFrameObject(frame);
     if (f == NULL) {
         return -1;
     }
+    PyThreadState_EnterTracing(tstate);
     assert (frame->f_lasti >= 0);
     initialize_trace_info(&tstate->trace_info, frame);
     f->f_lineno = _PyCode_CheckLineNumber(frame->f_lasti*sizeof(_Py_CODEUNIT), &tstate->trace_info.bounds);
     result = func(obj, f, what, arg);
     f->f_lineno = 0;
-    _PyThreadState_ResumeTracing(tstate);
-    tstate->tracing--;
+    PyThreadState_LeaveTracing(tstate);
     return result;
 }
 
@@ -6706,7 +6719,6 @@ _PyEval_CallTracing(PyObject *func, PyObject *args)
     PyObject *result;
 
     tstate->tracing = 0;
-    _PyThreadState_ResumeTracing(tstate);
     result = PyObject_Call(func, args, NULL);
     tstate->tracing = save_tracing;
     tstate->cframe->use_tracing = save_use_tracing;
@@ -6773,7 +6785,7 @@ _PyEval_SetProfile(PyThreadState *tstate, Py_tracefunc func, PyObject *arg)
     tstate->c_profilefunc = NULL;
     tstate->c_profileobj = NULL;
     /* Must make sure that tracing is not ignored if 'profileobj' is freed */
-    _PyThreadState_ResumeTracing(tstate);
+    _PyThreadState_UpdateTracingState(tstate);
     Py_XDECREF(profileobj);
 
     Py_XINCREF(arg);
@@ -6781,7 +6793,7 @@ _PyEval_SetProfile(PyThreadState *tstate, Py_tracefunc func, PyObject *arg)
     tstate->c_profilefunc = func;
 
     /* Flag that tracing or profiling is turned on */
-    _PyThreadState_ResumeTracing(tstate);
+    _PyThreadState_UpdateTracingState(tstate);
     return 0;
 }
 
@@ -6814,7 +6826,7 @@ _PyEval_SetTrace(PyThreadState *tstate, Py_tracefunc func, PyObject *arg)
     tstate->c_tracefunc = NULL;
     tstate->c_traceobj = NULL;
     /* Must make sure that profiling is not ignored if 'traceobj' is freed */
-    _PyThreadState_ResumeTracing(tstate);
+    _PyThreadState_UpdateTracingState(tstate);
     Py_XDECREF(traceobj);
 
     Py_XINCREF(arg);
@@ -6822,7 +6834,7 @@ _PyEval_SetTrace(PyThreadState *tstate, Py_tracefunc func, PyObject *arg)
     tstate->c_tracefunc = func;
 
     /* Flag that tracing or profiling is turned on */
-    _PyThreadState_ResumeTracing(tstate);
+    _PyThreadState_UpdateTracingState(tstate);
 
     return 0;
 }

Python/pystate.c

@@ -1333,23 +1333,6 @@ PyThreadState_SetAsyncExc(unsigned long id, PyObject *exc)
     return 0;
 }
 
-
-void
-PyThreadState_EnterTracing(PyThreadState *tstate)
-{
-    tstate->tracing++;
-    _PyThreadState_PauseTracing(tstate);
-}
-
-void
-PyThreadState_LeaveTracing(PyThreadState *tstate)
-{
-    tstate->tracing--;
-    _PyThreadState_ResumeTracing(tstate);
-}
-
-
-
 /* Routines for advanced debuggers, requested by David Beazley.
    Don't use unless you know what you are doing! */