[3.8] gh-112275: Fix HEAD_LOCK deadlock in child process after fork (GH-112336) ...

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)
(cherry picked from commit 0152431f179e85f582a4c393aa3b99d3918a1109)

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

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 (file)
index 0000000..d663be1
--- /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 2ec8458cb51bfb62fcfacbc76142725e08c575c1..0059be2e9a0b3a9c0f786ba969ef61a67546cd3b 100644 (file)
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -472,10 +472,10 @@ PyOS_AfterFork_Child(void)
 {
     _PyRuntimeState *runtime = &_PyRuntime;
     _PyGILState_Reinit(runtime);
+    _PyRuntimeState_ReInitThreads(runtime);
     _PyEval_ReInitThreads(runtime);
     _PyImport_ReInitLock();
     _PySignal_AfterFork();
-    _PyRuntimeState_ReInitThreads(runtime);
     _PyInterpreterState_DeleteExceptMain(runtime);
 
     run_at_forkers(_PyInterpreterState_Get()->after_forkers_child, 0);