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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 09FF4C432BE for ; Mon, 9 Aug 2021 01:13:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CFC4660F4B for ; Mon, 9 Aug 2021 01:13:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232563AbhHIBOM (ORCPT ); Sun, 8 Aug 2021 21:14:12 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:8377 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230076AbhHIBOK (ORCPT ); Sun, 8 Aug 2021 21:14:10 -0400 Received: from dggemv711-chm.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4GjdKZ30zQz85Ps; Mon, 9 Aug 2021 09:09:54 +0800 (CST) Received: from dggpemm500001.china.huawei.com (7.185.36.107) by dggemv711-chm.china.huawei.com (10.1.198.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Mon, 9 Aug 2021 09:13:49 +0800 Received: from [10.174.177.243] (10.174.177.243) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Mon, 9 Aug 2021 09:13:47 +0800 Subject: Re: [PATCH v2] once: Fix panic when module unload To: Hannes Frederic Sowa , , , David Miller CC: Andrew Morton , Greg Kroah-Hartman , Daniel Borkmann , "Eric Dumazet" , Minmin chen References: <20210806082124.96607-1-wangkefeng.wang@huawei.com> <7ae60193-0114-46d2-9770-697a2f88b85b@www.fastmail.com> From: Kefeng Wang Message-ID: <25dd38c6-39e7-8fb8-dff3-5062acf959c4@huawei.com> Date: Mon, 9 Aug 2021 09:13:47 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <7ae60193-0114-46d2-9770-697a2f88b85b@www.fastmail.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/8/6 23:22, Hannes Frederic Sowa wrote: > On Fri, Aug 6, 2021, at 10:21, Kefeng Wang wrote: >> DO_ONCE >> DEFINE_STATIC_KEY_TRUE(___once_key); >> __do_once_done >> once_disable_jump(once_key); >> INIT_WORK(&w->work, once_deferred); >> struct once_work *w; >> w->key = key; >> schedule_work(&w->work); module unload >> //*the key is >> destroy* >> process_one_work >> once_deferred >> BUG_ON(!static_key_enabled(work->key)); >> static_key_count((struct static_key *)x) //*access key, crash* >> >> When module uses DO_ONCE mechanism, it could crash due to the above >> concurrency problem, we could reproduce it with link[1]. >> >> Fix it by add/put module refcount in the once work process. >> >> [1] >> https://lore.kernel.org/netdev/eaa6c371-465e-57eb-6be9-f4b16b9d7cbf@huawei.com/ >> >> Cc: Hannes Frederic Sowa >> Cc: Daniel Borkmann >> Cc: David S. Miller >> Cc: Eric Dumazet >> Reported-by: Minmin chen >> Signed-off-by: Kefeng Wang > Acked-by: Hannes Frederic Sowa Thanks. > > Thanks, > Hannes > . >