bpo-40839: PyDict_GetItem() requires the GIL (GH-20580)
Calling PyDict_GetItem() without GIL held had been allowed for
historical reason. It is no longer allowed.
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index 809a5ed..c4d5da5 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -112,7 +112,8 @@
#include "Python.h"
#include "pycore_gc.h" // _PyObject_GC_IS_TRACKED()
-#include "pycore_object.h"
+#include "pycore_object.h" // _PyObject_GC_TRACK()
+#include "pycore_pyerrors.h" // _PyErr_Fetch()
#include "pycore_pystate.h" // _PyThreadState_GET()
#include "dict-common.h"
#include "stringlib/eq.h" // unicode_eq()
@@ -1387,14 +1388,12 @@
PyObject *
PyDict_GetItem(PyObject *op, PyObject *key)
{
- Py_hash_t hash;
- Py_ssize_t ix;
- PyDictObject *mp = (PyDictObject *)op;
- PyThreadState *tstate;
- PyObject *value;
-
- if (!PyDict_Check(op))
+ if (!PyDict_Check(op)) {
return NULL;
+ }
+ PyDictObject *mp = (PyDictObject *)op;
+
+ Py_hash_t hash;
if (!PyUnicode_CheckExact(key) ||
(hash = ((PyASCIIObject *) key)->hash) == -1)
{
@@ -1405,28 +1404,26 @@
}
}
- /* We can arrive here with a NULL tstate during initialization: try
- running "python -Wi" for an example related to string interning.
- Let's just hope that no exception occurs then... This must be
- _PyThreadState_GET() and not PyThreadState_Get() because the latter
- abort Python if tstate is NULL. */
- tstate = _PyThreadState_GET();
- if (tstate != NULL && tstate->curexc_type != NULL) {
- /* preserve the existing exception */
- PyObject *err_type, *err_value, *err_tb;
- PyErr_Fetch(&err_type, &err_value, &err_tb);
- ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value);
- /* ignore errors */
- PyErr_Restore(err_type, err_value, err_tb);
- if (ix < 0)
- return NULL;
- }
- else {
- ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value);
- if (ix < 0) {
- PyErr_Clear();
- return NULL;
- }
+ PyThreadState *tstate = _PyThreadState_GET();
+#ifdef Py_DEBUG
+ // bpo-40839: Before Python 3.10, it was possible to call PyDict_GetItem()
+ // with the GIL released.
+ _Py_EnsureTstateNotNULL(tstate);
+#endif
+
+ /* Preserve the existing exception */
+ PyObject *exc_type, *exc_value, *exc_tb;
+ PyObject *value;
+ Py_ssize_t ix;
+
+ _PyErr_Fetch(tstate, &exc_type, &exc_value, &exc_tb);
+ ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value);
+
+ /* Ignore any exception raised by the lookup */
+ _PyErr_Restore(tstate, exc_type, exc_value, exc_tb);
+
+ if (ix < 0) {
+ return NULL;
}
return value;
}