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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=no 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 7DD92C73C63 for ; Wed, 10 Jul 2019 03:09:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5D38A20656 for ; Wed, 10 Jul 2019 03:09:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726126AbfGJDJY (ORCPT ); Tue, 9 Jul 2019 23:09:24 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:2249 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725935AbfGJDJY (ORCPT ); Tue, 9 Jul 2019 23:09:24 -0400 Received: from DGGEMS409-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id B20CB753DD21332D48C9; Wed, 10 Jul 2019 11:09:18 +0800 (CST) Received: from use12-sp2.huawei.com (10.67.189.174) by DGGEMS409-HUB.china.huawei.com (10.3.19.209) with Microsoft SMTP Server id 14.3.439.0; Wed, 10 Jul 2019 11:09:10 +0800 From: Xiaoming Ni To: , , , , , , , , , , , , , , , , , , , , CC: , , , , , Subject: [PATCH v3 0/3] kernel/notifier.c: avoid duplicate registration Date: Wed, 10 Jul 2019 11:09:07 +0800 Message-ID: <1562728147-30251-1-git-send-email-nixiaoming@huawei.com> X-Mailer: git-send-email 1.8.5.6 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.67.189.174] X-CFilter-Loop: Reflected Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Registering the same notifier to a hook repeatedly can cause the hook list to form a ring or lose other members of the list. case1: An infinite loop in notifier_chain_register() can cause soft lockup atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_chain_register(&test_notifier_list, &test2); case2: An infinite loop in notifier_chain_register() can cause soft lockup atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_call_chain(&test_notifier_list, 0, NULL); case3: lose other hook test2 atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_chain_register(&test_notifier_list, &test2); atomic_notifier_chain_register(&test_notifier_list, &test1); case4: Unregister returns 0, but the hook is still in the linked list, and it is not really registered. If you call notifier_call_chain after ko is unloaded, it will trigger oops. if the system is configured with softlockup_panic and the same hook is repeatedly registered on the panic_notifier_list, it will cause a loop panic. so. need add a check in in notifier_chain_register() to avoid duplicate registration v1: * use notifier_chain_cond_register replace notifier_chain_register v2: * Add a check in notifier_chain_register() to avoid duplicate registration * remove notifier_chain_cond_register() to avoid duplicate code * remove blocking_notifier_chain_cond_register() to avoid duplicate code v3: * Add a cover letter. Xiaoming Ni (3): kernel/notifier.c: avoid duplicate registration kernel/notifier.c: remove notifier_chain_cond_register() kernel/notifier.c: remove blocking_notifier_chain_cond_register() include/linux/notifier.h | 4 ---- kernel/notifier.c | 41 +++-------------------------------------- net/sunrpc/rpc_pipe.c | 2 +- 3 files changed, 4 insertions(+), 43 deletions(-) -- 1.8.5.6