From 7bdfabe2d1ec353ecdc75a5aec41cce83e572391 Mon Sep 17 00:00:00 2001
From: "T. Wouters" <thomas@python.org>
Date: Mon, 30 Sep 2024 16:41:46 -0700
Subject: [PATCH] gh-124785: Revert "gh-116510: Fix crash due to shared
 immortal interned strings (gh-124646)" (gh-124807)

Revert "gh-116510: Fix crash due to shared immortal interned strings. (gh-124646)"

This reverts commit 98b2ed7e239c807f379cd2bf864f372d79064aac.
---
 ...-09-26-18-21-06.gh-issue-116510.FacUWO.rst |  5 --
 Objects/unicodeobject.c                       | 48 +++----------------
 2 files changed, 6 insertions(+), 47 deletions(-)
 delete mode 100644 Misc/NEWS.d/next/Core_and_Builtins/2024-09-26-18-21-06.gh-issue-116510.FacUWO.rst

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2024-09-26-18-21-06.gh-issue-116510.FacUWO.rst b/Misc/NEWS.d/next/Core_and_Builtins/2024-09-26-18-21-06.gh-issue-116510.FacUWO.rst
deleted file mode 100644
index e3741321006..00000000000
--- a/Misc/NEWS.d/next/Core_and_Builtins/2024-09-26-18-21-06.gh-issue-116510.FacUWO.rst
+++ /dev/null
@@ -1,5 +0,0 @@
-Fix a crash caused by immortal interned strings being shared between
-sub-interpreters that use basic single-phase init.  In that case, the string
-can be used by an interpreter that outlives the interpreter that created and
-interned it.  For interpreters that share obmalloc state, also share the
-interned dict with the main interpreter.
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 0f502ccdaf5..e9589cfe44f 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -282,37 +282,13 @@ hashtable_unicode_compare(const void *key1, const void *key2)
     }
 }
 
-/* Return true if this interpreter should share the main interpreter's
-   intern_dict.  That's important for interpreters which load basic
-   single-phase init extension modules (m_size == -1).  There could be interned
-   immortal strings that are shared between interpreters, due to the
-   PyDict_Update(mdict, m_copy) call in import_find_extension().
-
-   It's not safe to deallocate those strings until all interpreters that
-   potentially use them are freed.  By storing them in the main interpreter, we
-   ensure they get freed after all other interpreters are freed.
-*/
-static bool
-has_shared_intern_dict(PyInterpreterState *interp)
-{
-    PyInterpreterState *main_interp = _PyInterpreterState_Main();
-    return interp != main_interp  && interp->feature_flags & Py_RTFLAGS_USE_MAIN_OBMALLOC;
-}
-
 static int
 init_interned_dict(PyInterpreterState *interp)
 {
     assert(get_interned_dict(interp) == NULL);
-    PyObject *interned;
-    if (has_shared_intern_dict(interp)) {
-        interned = get_interned_dict(_PyInterpreterState_Main());
-        Py_INCREF(interned);
-    }
-    else {
-        interned = PyDict_New();
-        if (interned == NULL) {
-            return -1;
-        }
+    PyObject *interned = interned = PyDict_New();
+    if (interned == NULL) {
+        return -1;
     }
     _Py_INTERP_CACHED_OBJECT(interp, interned_strings) = interned;
     return 0;
@@ -323,10 +299,7 @@ clear_interned_dict(PyInterpreterState *interp)
 {
     PyObject *interned = get_interned_dict(interp);
     if (interned != NULL) {
-        if (!has_shared_intern_dict(interp)) {
-            // only clear if the dict belongs to this interpreter
-            PyDict_Clear(interned);
-        }
+        PyDict_Clear(interned);
         Py_DECREF(interned);
         _Py_INTERP_CACHED_OBJECT(interp, interned_strings) = NULL;
     }
@@ -15645,13 +15618,6 @@ _PyUnicode_ClearInterned(PyInterpreterState *interp)
     }
     assert(PyDict_CheckExact(interned));
 
-    if (has_shared_intern_dict(interp)) {
-        // the dict doesn't belong to this interpreter, skip the debug
-        // checks on it and just clear the pointer to it
-        clear_interned_dict(interp);
-        return;
-    }
-
 #ifdef INTERNED_STATS
     fprintf(stderr, "releasing %zd interned strings\n",
             PyDict_GET_SIZE(interned));
@@ -16160,10 +16126,8 @@ _PyUnicode_Fini(PyInterpreterState *interp)
 {
     struct _Py_unicode_state *state = &interp->unicode;
 
-    if (!has_shared_intern_dict(interp)) {
-        // _PyUnicode_ClearInterned() must be called before _PyUnicode_Fini()
-        assert(get_interned_dict(interp) == NULL);
-    }
+    // _PyUnicode_ClearInterned() must be called before _PyUnicode_Fini()
+    assert(get_interned_dict(interp) == NULL);
 
     _PyUnicode_FiniEncodings(&state->fs_codec);