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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 140F7C072A2 for ; Fri, 17 Nov 2023 12:43:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230085AbjKQMnL (ORCPT ); Fri, 17 Nov 2023 07:43:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34524 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229436AbjKQMnL (ORCPT ); Fri, 17 Nov 2023 07:43:11 -0500 Received: from out30-133.freemail.mail.aliyun.com (out30-133.freemail.mail.aliyun.com [115.124.30.133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 145FFD52; Fri, 17 Nov 2023 04:43:06 -0800 (PST) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R931e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046050;MF=alibuda@linux.alibaba.com;NM=1;PH=DS;RN=13;SR=0;TI=SMTPD_---0VwZqNA0_1700224983; Received: from 192.168.50.70(mailfrom:alibuda@linux.alibaba.com fp:SMTPD_---0VwZqNA0_1700224983) by smtp.aliyun-inc.com; Fri, 17 Nov 2023 20:43:04 +0800 Message-ID: <6ebbb7ab-f053-d212-6d88-7eb6754f12a6@linux.alibaba.com> Date: Fri, 17 Nov 2023 20:43:03 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [PATCH net v2] net/smc: avoid data corruption caused by decline Content-Language: en-US To: Wenjia Zhang , kgraul@linux.ibm.com, jaka@linux.ibm.com, wintera@linux.ibm.com, guwen@linux.alibaba.com Cc: kuba@kernel.org, davem@davemloft.net, netdev@vger.kernel.org, linux-s390@vger.kernel.org, linux-rdma@vger.kernel.org, tonylu@linux.alibaba.com, pabeni@redhat.com, edumazet@google.com References: <1700197181-83136-1-git-send-email-alibuda@linux.alibaba.com> <7fe3a213-3d2e-42d5-b44b-bbd761a01bba@linux.ibm.com> From: "D. Wythe" In-Reply-To: <7fe3a213-3d2e-42d5-b44b-bbd761a01bba@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On 11/17/23 8:35 PM, Wenjia Zhang wrote: > > > On 17.11.23 05:59, D. Wythe wrote: >> From: "D. Wythe" >> >> We found a data corruption issue during testing of SMC-R on Redis >> applications. >> >> The benchmark has a low probability of reporting a strange error as >> shown below. >> >> "Error: Protocol error, got "\xe2" as reply type byte" >> >> Finally, we found that the retrieved error data was as follows: >> >> 0xE2 0xD4 0xC3 0xD9 0x04 0x00 0x2C 0x20 0xA6 0x56 0x00 0x16 0x3E 0x0C >> 0xCB 0x04 0x02 0x01 0x00 0x00 0x20 0x00 0x00 0x00 0x00 0x00 0x00 0x00 >> 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0xE2 >> >> It is quite obvious that this is a SMC DECLINE message, which means that >> the applications received SMC protocol message. >> We found that this was caused by the following situations: >> >> client            server >>        proposal >>     -------------> >>        accept >>     <------------- >>        confirm >>     -------------> >> wait confirm >> >>      failed llc confirm >>         x------ >> (after 2s)timeout >>             wait rsp >> >> wait decline >> >> (after 1s) timeout >>             (after 2s) timeout >>         decline >>     --------------> >>         decline >>     <-------------- >> >> As a result, a decline message was sent in the implementation, and this >> message was read from TCP by the already-fallback connection. >> >> This patch double the client timeout as 2x of the server value, >> With this simple change, the Decline messages should never cross or >> collide (during Confirm link timeout). >> >> This issue requires an immediate solution, since the protocol updates >> involve a more long-term solution. >> > > Hi D.Wythe, > > I think you understood me wrong. I mean we don't need sysctl. I like > the first version more, where you just need to add some comments in > the code. > 😅, ok that. I understood it with wrong way. I will resend the first version with comments. > Thanks, > Wenjia