From: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com>
Date: Wed, 4 Sep 2024 17:26:29 +0000 (+0200)
Subject: [3.10] gh-112275: Fix HEAD_LOCK deadlock in child process after fork (GH-112336)... 
X-Git-Tag: v3.10.15~5
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=d3f39cefe721db643957d48316ac98c5e279f0c3;p=thirdparty%2FPython%2Fcpython.git

[3.10] gh-112275: Fix HEAD_LOCK deadlock in child process after fork (GH-112336) (#123687)

HEAD_LOCK is called from _PyEval_ReInitThreads->_PyThreadState_DeleteExcept before _PyRuntimeState_ReInitThreads reinit runtime->interpreters.mutex which might be locked before fork.

(cherry picked from commit 522799a05e3e820339718151ac055af6d864d463)

Co-authored-by: ChuBoning <102216855+ChuBoning@users.noreply.github.com>
Co-authored-by: Łukasz Langa <lukasz@langa.pl>
---

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2024-09-04-18-20-11.gh-issue-112275.W_iMiB.rst b/Misc/NEWS.d/next/Core_and_Builtins/2024-09-04-18-20-11.gh-issue-112275.W_iMiB.rst
new file mode 100644
index 000000000000..d663be1867ed
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2024-09-04-18-20-11.gh-issue-112275.W_iMiB.rst
@@ -0,0 +1,3 @@
+A deadlock involving ``pystate.c``'s ``HEAD_LOCK`` in ``posixmodule.c``
+at fork is now fixed. Patch by ChuBoning based on previous Python 3.12
+fix by Victor Stinner.
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 43e69fc322b5..feffa43cfd0d 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -598,6 +598,11 @@ PyOS_AfterFork_Child(void)
         goto fatal_error;
     }
 
+    status = _PyRuntimeState_ReInitThreads(runtime);
+    if (_PyStatus_EXCEPTION(status)) {
+        goto fatal_error;
+    }
+
     PyThreadState *tstate = _PyThreadState_GET();
     _Py_EnsureTstateNotNULL(tstate);
 
@@ -613,11 +618,6 @@ PyOS_AfterFork_Child(void)
 
     _PySignal_AfterFork();
 
-    status = _PyRuntimeState_ReInitThreads(runtime);
-    if (_PyStatus_EXCEPTION(status)) {
-        goto fatal_error;
-    }
-
     status = _PyInterpreterState_DeleteExceptMain(runtime);
     if (_PyStatus_EXCEPTION(status)) {
         goto fatal_error;