bpo-42500: Fix recursion in or after except (GH-23568)

* Use counter, rather boolean state when handling soft overflows.

2 files changed, 1 insertions, 18 deletions

diff --git a/Include/cpython/pystate.h b/Include/cpython/pystate.h
index 0e6cc290912..cfaee890f97 100644
--- a/Include/cpython/pystate.h
+++ b/Include/cpython/pystate.h
@@ -54,8 +54,7 @@ struct _ts {
     /* Borrowed reference to the current frame (it can be NULL) */
     PyFrameObject *frame;
     int recursion_depth;
-    char overflowed; /* The stack has overflowed. Allow 50 more calls
-                        to handle the runtime error. */
+    int recursion_headroom; /* Allow 50 more calls to handle any errors. */
     int stackcheck_counter;
 
     /* 'tracing' keeps track of the execution depth when tracing/profiling.
diff --git a/Include/internal/pycore_ceval.h b/Include/internal/pycore_ceval.h
index bbb667ea32d..38fd681f20c 100644
--- a/Include/internal/pycore_ceval.h
+++ b/Include/internal/pycore_ceval.h
@@ -92,24 +92,8 @@ static inline int _Py_EnterRecursiveCall_inline(const char *where) {
 
 #define Py_EnterRecursiveCall(where) _Py_EnterRecursiveCall_inline(where)
 
-/* Compute the "lower-water mark" for a recursion limit. When
- * Py_LeaveRecursiveCall() is called with a recursion depth below this mark,
- * the overflowed flag is reset to 0. */
-static inline int _Py_RecursionLimitLowerWaterMark(int limit) {
-    if (limit > 200) {
-        return (limit - 50);
-    }
-    else {
-        return (3 * (limit >> 2));
-    }
-}
-
 static inline void _Py_LeaveRecursiveCall(PyThreadState *tstate)  {
     tstate->recursion_depth--;
-    int limit = tstate->interp->ceval.recursion_limit;
-    if (tstate->recursion_depth < _Py_RecursionLimitLowerWaterMark(limit)) {
-        tstate->overflowed = 0;
-    }
 }
 
 static inline void _Py_LeaveRecursiveCall_inline(void)  {