thread.c: fix race between read and close

* thread.c (rb_thread_fd_close): wait until all threads using the
  fd finish the operation, not to free the buffer in use.
  [ruby-core:78845] [Bug #13076]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57202 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

thread.c

@@ -2164,14 +2164,22 @@ rb_thread_fd_close(int fd)
 {
     rb_vm_t *vm = GET_THREAD()->vm;
     rb_thread_t *th = 0;
+    int busy;
 
+  retry:
+    busy = 0;
     list_for_each(&vm->living_threads, th, vmlt_node) {
 	if (th->waiting_fd == fd) {
 	    VALUE err = th->vm->special_exceptions[ruby_error_closed_stream];
 	    rb_threadptr_pending_interrupt_enque(th, err);
 	    rb_threadptr_interrupt(th);
+	    busy = 1;
 	}
     }
+    if (busy) {
+	rb_thread_schedule_limits(0);
+	goto retry;
+    }
 }
 
 /*