From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2C1E9C43381 for ; Tue, 12 Mar 2019 08:06:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F3413214AE for ; Tue, 12 Mar 2019 08:06:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727487AbfCLIGj (ORCPT ); Tue, 12 Mar 2019 04:06:39 -0400 Received: from relay.sw.ru ([185.231.240.75]:52928 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726633AbfCLIGj (ORCPT ); Tue, 12 Mar 2019 04:06:39 -0400 Received: from [172.16.24.21] by relay.sw.ru with esmtp (Exim 4.91) (envelope-from ) id 1h3cQj-0003BY-8R; Tue, 12 Mar 2019 11:06:33 +0300 From: Vasily Averin Subject: [PATCH] notifiers: double register detection To: linux-kernel@vger.kernel.org, Andrew Morton Message-ID: <04127e71-4782-9bbb-fe5a-7c01e93a99b0@virtuozzo.com> Date: Tue, 12 Mar 2019 11:06:32 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org By design notifiers can be registerd once only, 2nd register attempt called by mistake silently corrupts notifiers list. Proposed check cannot prevent described problem, however it allows to detect its reason quickly without coredump analyze. Signed-off-by: Vasily Averin --- kernel/notifier.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/notifier.c b/kernel/notifier.c index 6196af8a8223..bfc95b3e4235 100644 --- a/kernel/notifier.c +++ b/kernel/notifier.c @@ -22,6 +22,7 @@ static int notifier_chain_register(struct notifier_block **nl, struct notifier_block *n) { while ((*nl) != NULL) { + WARN_ONCE(((*nl) == n), "double register detected"); if (n->priority > (*nl)->priority) break; nl = &((*nl)->next); -- 2.17.1