From 0009ed864960b5b45d9f6492827af52c2dddf9f3 Mon Sep 17 00:00:00 2001
From: Jason Fried <me@jasonfried.info>
Date: Mon, 22 May 2017 16:58:55 -0700
Subject: [PATCH] [3.6] bpo-30395 _PyGILState_Reinit deadlock fix (GH-1734)

head_lock could be held by another thread when fork happened. We should
reset it to avoid deadlock.
(cherry picked from commit f82c951d1c5416f3550d544e50ff5662d3836e73)
---
 Misc/ACKS        | 1 +
 Python/pystate.c | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/Misc/ACKS b/Misc/ACKS
index 7109ccbe851384..b8bac248d98867 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -552,6 +552,7 @@ Eric Groo
 Daniel Andrade Groppe
 Dag Gruneau
 Filip Gruszczyński
+Andrii Grynenko
 Grzegorz Grzywacz
 Thomas Guettler
 Yuyang Guo
diff --git a/Python/pystate.c b/Python/pystate.c
index 65c244e6f73617..ccb0092c42b3a4 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -743,6 +743,10 @@ _PyGILState_Fini(void)
 void
 _PyGILState_Reinit(void)
 {
+#ifdef WITH_THREAD
+    head_mutex = NULL;
+    HEAD_INIT();
+#endif
     PyThreadState *tstate = PyGILState_GetThisThreadState();
     PyThread_delete_key(autoTLSkey);
     if ((autoTLSkey = PyThread_create_key()) == -1)