thread_pthread.c: reinitialize ubf_list at fork

It's possible for the ubf_list_head to be populated with dead
threads at fork or the ubf_list_lock to be held, so reinitialize
both at startup.

And while we're at it, use a static initializer at startup
to save a library call and kill some ifdef.

[ruby-core:88578] [Bug #15013]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64485 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

thread.c

@@ -4396,6 +4396,7 @@ rb_thread_atfork_internal(rb_thread_t *th, void (*atfork)(rb_thread_t *, const r
     vm->main_thread = th;
 
     gvl_atfork(th->vm);
+    ubf_list_atfork();
 
     list_for_each(&vm->living_threads, i, vmlt_node) {
 	atfork(i, th);

thread_pthread.c

@@ -532,10 +532,6 @@ native_cond_timeout(rb_nativethread_cond_t *cond, struct timespec timeout_rel)
 #define native_cleanup_push pthread_cleanup_push
 #define native_cleanup_pop  pthread_cleanup_pop
 
-#if defined(USE_UBF_LIST)
-static rb_nativethread_lock_t ubf_list_lock;
-#endif
-
 static pthread_key_t ruby_native_thread_key;
 
 static void
@@ -574,9 +570,6 @@ Init_native_thread(rb_thread_t *th)
     th->thread_id = pthread_self();
     fill_thread_id_str(th);
     native_thread_init(th);
-#ifdef USE_UBF_LIST
-    rb_native_mutex_initialize(&ubf_list_lock);
-#endif
     posix_signal(SIGVTALRM, null_func);
 }
 
@@ -1268,6 +1261,14 @@ native_cond_sleep(rb_thread_t *th, struct timespec *timeout_rel)
 
 #ifdef USE_UBF_LIST
 static LIST_HEAD(ubf_list_head);
+static rb_nativethread_lock_t ubf_list_lock = RB_NATIVETHREAD_LOCK_INIT;
+
+static void
+ubf_list_atfork(void)
+{
+    list_head_init(&ubf_list_head);
+    rb_native_mutex_initialize(&ubf_list_lock);
+}
 
 /* The thread 'th' is registered to be trying unblock. */
 static void

thread_win32.c

@@ -23,6 +23,7 @@
 #define ubf_wakeup_all_threads() do {} while (0)
 #define ubf_threads_empty() (1)
 #define ubf_timer_disarm() do {} while (0)
+#define ubf_list_atfork() do {} while (0)
 
 static volatile DWORD ruby_native_thread_key = TLS_OUT_OF_INDEXES;