From f6fb95dbf5fce38b18c5ce0a88489ee16520006d Mon Sep 17 00:00:00 2001
From: normal <normal@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Mon, 30 Jul 2018 21:48:32 +0000
Subject: thread_pthread.c (unregister_ubf_list): assert unblock.func is unset

We must not allow reentry into ubf_list_head once we delete
ourselves, otherwise we could hang in there forever.

[ruby-core:88218] [Bug #14945]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64134 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 thread_pthread.c | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'thread_pthread.c')

diff --git a/thread_pthread.c b/thread_pthread.c
index 844a4bc800..c8487e55f1 100644
--- a/thread_pthread.c
+++ b/thread_pthread.c
@@ -1178,6 +1178,9 @@ unregister_ubf_list(rb_thread_t *th)
 {
     struct list_node *node = &th->native_thread_data.ubf_list;
 
+    /* we can't allow re-entry into ubf_list_head */
+    VM_ASSERT(th->unblock.func == 0);
+
     if (!list_empty((struct list_head*)node)) {
         rb_native_mutex_lock(&ubf_list_lock);
 	list_del_init(node);
-- 
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