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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 0BE82C43381 for ; Sat, 16 Mar 2019 02:41:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C45C621872 for ; Sat, 16 Mar 2019 02:41:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726653AbfCPCeS (ORCPT ); Fri, 15 Mar 2019 22:34:18 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:42322 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726218AbfCPCeS (ORCPT ); Fri, 15 Mar 2019 22:34:18 -0400 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 1D098109E3AE7366AEFB; Sat, 16 Mar 2019 10:34:15 +0800 (CST) Received: from [127.0.0.1] (10.184.225.177) by DGGEMS402-HUB.china.huawei.com (10.3.19.202) with Microsoft SMTP Server id 14.3.408.0; Sat, 16 Mar 2019 10:34:08 +0800 Subject: Re: [PATCH v2] vxlan: remove the redundant gro_cells_destroy() calling. To: Eric Dumazet , David Miller CC: , , , , , , , , References: <20190315162824.732b18ac@elisabeth> <005ad387-8d51-561e-a5b9-8e851e03d5e9@gmail.com> <20190315.110249.648596993203657814.davem@davemloft.net> From: Zhiqiang Liu Message-ID: Date: Sat, 16 Mar 2019 10:33:14 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.184.225.177] X-CFilter-Loop: Reflected Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org >>> On 03/15/2019 08:28 AM, Stefano Brivio wrote: >>>> On Fri, 15 Mar 2019 23:18:52 +0800 >>>> Zhiqiang Liu wrote: >>>> >>>> >>>> NACK, please read my and Eric's comments to v1 -- giving me more than 23 >>>> minutes to answer would have been a nice touch as well :) >>>> >>> >>> Sorry for the confusion, I forgot to add the question marks to my sentences. >>> >>> In fact, this is a bug fix, that we missed in the previous fix. >>> >>> Technically the bug is older. >> >> Please elaborate. >> > > Commit ad6c9986bcb62 > ("vxlan: Fix GRO cells race condition between receive and link delete") > > fixed a race condition for the typical case a vxlan device is dismantled from the > current netns. > > But if a netns is dismantled, we call vxlan_destroy_tunnels() > to schedule a unregister_netdevice_queue() of all the vxlan tunnels > that are related to this netns. > > This means that the gro_cells_destroy() call is done too soon, > for the same reasons explained in above commit . > > We need to fully respect the RCU rules, and thus must remove the > gro_cells_destroy() call or risk use after-free. > > The bug is day-0 I think. > > commit 58ce31cca1ffe057f4744c3f671e3e84606d3d4a > Author: Tom Herbert > Date: Wed Aug 19 17:07:33 2015 -0700 > > vxlan: GRO support at tunnel layer > Thank you for pointing out the real issueI will update the commit message and Fixes: tag as your explanation.