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=-4.0 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS autolearn=unavailable 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 460FFC43381 for ; Fri, 1 Mar 2019 08:44:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 105712087E for ; Fri, 1 Mar 2019 08:44:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=cogentembedded-com.20150623.gappssmtp.com header.i=@cogentembedded-com.20150623.gappssmtp.com header.b="XKVl5KlS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731846AbfCAIn6 (ORCPT ); Fri, 1 Mar 2019 03:43:58 -0500 Received: from mail-lj1-f194.google.com ([209.85.208.194]:37199 "EHLO mail-lj1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727052AbfCAIn5 (ORCPT ); Fri, 1 Mar 2019 03:43:57 -0500 Received: by mail-lj1-f194.google.com with SMTP id a17so19636638ljd.4 for ; Fri, 01 Mar 2019 00:43:56 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cogentembedded-com.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=dHgrxAerKH54EZRV7lKiut97ONmA2OZmvWj2BlwqLOY=; b=XKVl5KlSMJdjz3CJzWWeLj4dzdU4PtQR3/sfXrzoeTK8wBSGK+ksybq+laZTGF2KhH khrHg7ldJmB451J1av30w2FMnjo7+3EOtgkMFVrvwg8SNMFkbsgZdnbsYCZRsUDAyddP CUC37IoSuZWUPcPiwvCWiECqRn38c/URe5/8NagxZfiDiHag5lYeop5flUEzZ8zGjzl6 j0YLJkzCbJNqHJ3wwcsy5ZF+VnKftGSMgMT9JN3Nkft8l8xynp0bqxPEzMzq3IlkkR3V 0gCwwc7wvM0uxi83HjNBkQAuK9GWy5jGw9PUKglRioOieksQKOwv5PpQLywn+2M77hjQ b+1A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=dHgrxAerKH54EZRV7lKiut97ONmA2OZmvWj2BlwqLOY=; b=bb6Xy8KGTBjT/RZDpaPD4yNSczdS642KOSoN520uJr6qn48fYvGv9Wf7l+Yz84GtdW uOGoFkUHWbiYZVyF82VDHhzzzUcFtuvVMLag16sV6shj8mnwnqW8RrvvtZO0KiWlJPyM je1RAeFHar3jP4ISZdxt/FHQW+IHhvn5H4bTBJ2D8JgNzeebGrx+JOAve2pdw/jyCEip sziitMGnsxebhwKuli9f47nM+lkX+G3wnftNQRQKNMpm9LCWx6J65OTo/R8ogrOgGLUP Qw+OaJtdfGF3U1fW9d27rrWJHoGakJ7+GWsnV9Ly7xWUJgK/S9fIFXxAgb3MQNpy/c+Y UDeQ== X-Gm-Message-State: APjAAAUxTtugipkmL8+f/e0tivFix5SLs/7J7KQg8NEQ8cYLZOH2B3PP injNieeJQYTVscoW3PPo1ytHtA== X-Google-Smtp-Source: APXvYqyduSqNJSMaOgFcCE2INrR9e84+FFK4Ti4nhBs1TO68842Ad3eR6RLU8mJ1Ka84XKi4rw4neQ== X-Received: by 2002:a2e:9117:: with SMTP id m23mr1909761ljg.94.1551429835517; Fri, 01 Mar 2019 00:43:55 -0800 (PST) Received: from [192.168.0.199] ([31.173.84.89]) by smtp.gmail.com with ESMTPSA id a26sm1322361lfl.45.2019.03.01.00.43.54 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 01 Mar 2019 00:43:54 -0800 (PST) Subject: Re: [PATCH] netfilter: nf_ct_helper: Fix possible panic when nf_conntrack_helper_unregister is used in an unloadable module To: Su Yanjun , pablo@netfilter.org, kadlec@blackhole.kfki.hu, fw@strlen.de, davem@davemloft.net, netfilter-devel@vger.kernel.org, coreteam@netfilter.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: suyj.fnst@cn.fujitsu.com References: <1551419766-1039-1-git-send-email-suyanjun218@163.com> From: Sergei Shtylyov Message-ID: Date: Fri, 1 Mar 2019 11:43:43 +0300 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <1551419766-1039-1-git-send-email-suyanjun218@163.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hello! On 01.03.2019 8:56, Su Yanjun wrote: > From: Su Yanjun > > Because nf_conntrack_helper_unregister maybe used in an unloadable module, > it uses 'synchronize_rcu' which may cause kernel panic. > > According to the artical: Article? > RCU and Unloadable Modules > https://lwn.net/Articles/217484/ > > When we have a heavy rcu callback load, then some of the callbacks might be > deferred in order to allow other processing to proceed. sychnorize_rcu does > not wait rcu callback complete and module may be unloaded before callback > done. > > This patch uses rcu_barrier instead of synchronize_rcu will prevent this ^ that/which missed? > situation. > > Signed-off-by: Su Yanjun [...] MBR, Sergei