From 3a0620072a1986172787e48177763cb40a95273e Mon Sep 17 00:00:00 2001
From: Andrii Grynenko <andrii@fb.com>
Date: Mon, 22 May 2017 16:11:39 -0700
Subject: [PATCH] bpo-30395 _PyGILState_Reinit deadlock fix

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

diff --git a/Misc/ACKS b/Misc/ACKS
index 098c801fcb0fc9..b72c40c3330bc2 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -556,6 +556,7 @@ 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 8e81707c7cc559..52899f124a0aba 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -744,6 +744,10 @@ _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)