From: Sam Gross <colesbury@gmail.com>
Date: Thu, 16 Jul 2026 17:37:00 +0000 (-0700)
Subject: gh-149162: Use _Py_LOCK_DONT_DETACH in intern_common (gh-149164)
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f62050d65743f0c895f7e6d665936c4e86aa39d5;p=thirdparty%2FPython%2Fcpython.git

gh-149162: Use _Py_LOCK_DONT_DETACH in intern_common (gh-149164)

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

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 47cb7684eab8..6562546ae2f9 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -14722,7 +14722,7 @@ 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);