Add macro to assert critical section is held

Author: DinoV

Include/internal/pycore_critical_section.h

@@ -104,12 +104,29 @@ extern "C" {
 # define Py_END_CRITICAL_SECTION2()                                     \
         _PyCriticalSection2_End(&_cs2);                                 \
     }
+
+// Asserts that the mutex is locked.  The mutex must be held by the
+// top-most critical section otherwise there's the possibility
+// that the mutex would be swalled out in some code paths.
+#define  _Py_CRITICAL_SECTION_ASSERT_MUTEX_LOCKED(mutex) \
+    _PyCriticalSection_AssertHeld(mutex)
+
+// Asserts that the mutex for the given object is locked. The mutex must
+// be held by the top-most critical section otherwise there's the
+// possibility that the mutex would be swalled out in some code paths.
+#define  _Py_CRITICAL_SECTION_ASSERT_OBJECT_LOCKED(op) \
+    _Py_CRITICAL_SECTION_ASSERT_MUTEX_LOCKED(&_PyObject_CAST(op)->ob_mutex)
+
+
+
 #else  /* !Py_GIL_DISABLED */
 // The critical section APIs are no-ops with the GIL.
 # define Py_BEGIN_CRITICAL_SECTION(op)
 # define Py_END_CRITICAL_SECTION()
 # define Py_BEGIN_CRITICAL_SECTION2(a, b)
 # define Py_END_CRITICAL_SECTION2()
+# define _Py_CRITICAL_SECTION_ASSERT_MUTEX_LOCKED(mutex)
+# define _Py_CRITICAL_SECTION_ASSERT_OBJECT_LOCKED(op)
 #endif  /* !Py_GIL_DISABLED */
 
 typedef struct {
@@ -236,6 +253,19 @@ _PyCriticalSection2_End(_PyCriticalSection2 *c)
 PyAPI_FUNC(void)
 _PyCriticalSection_SuspendAll(PyThreadState *tstate);
 
+#ifdef Py_GIL_DISABLED
+
+static inline void
+_PyCriticalSection_AssertHeld(PyMutex *mutex) {
+#ifdef Py_DEBUG
+    PyThreadState *tstate = _PyThreadState_GET();
+    _PyCriticalSection *cs = (_PyCriticalSection *)tstate->critical_section;
+    assert(cs != NULL && cs->mutex == mutex);
+#endif
+}
+
+#endif
+
 #ifdef __cplusplus
 }
 #endif