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

1 files changed, 3 insertions, 0 deletions

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);