From: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com>
Date: Thu, 16 Jul 2026 18:59:43 +0000 (+0200)
Subject: [3.15] gh-149162: Use _Py_LOCK_DONT_DETACH in intern_common (gh-149164) (gh-153814)
X-Git-Tag: v3.15.0b4~9
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=38c3f112c383d1f61a3e2d2d4ff589a5ca570944;p=thirdparty%2FPython%2Fcpython.git

[3.15] gh-149162: Use _Py_LOCK_DONT_DETACH in intern_common (gh-149164) (gh-153814)

Avoids potential deadlocks with C++ static local initialization in
extensions that call PyUnicode_InternFromString during one-time
initialization.

(cherry picked from commit f62050d65743f0c895f7e6d665936c4e86aa39d5)

Co-authored-by: Sam Gross <colesbury@gmail.com>
---

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-04-29-15-10-59.gh-issue-149162.BPPyrq.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-04-29-15-10-59.gh-issue-149162.BPPyrq.rst
new file mode 100644
index 000000000000..b4c443ecee07
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-04-29-15-10-59.gh-issue-149162.BPPyrq.rst
@@ -0,0 +1,3 @@
+Fix a potential deadlock in :c:func:`PyUnicode_InternFromString` and other
+interning functions in the :term:`free-threaded build` when called from C++
+static local initializers.
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 18523c2dfde7..c3a1beee0c8a 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -14344,7 +14344,7 @@ intern_common(PyInterpreterState *interp, PyObject *s /* stolen */,
     }
 #endif
 
-    FT_MUTEX_LOCK(INTERN_MUTEX);
+    FT_MUTEX_LOCK_FLAGS(INTERN_MUTEX, _Py_LOCK_DONT_DETACH);
     PyObject *t;
     {
         int res = PyDict_SetDefaultRef(interned, s, s, &t);