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 28E54C6FD20 for ; Fri, 24 Mar 2023 03:42:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231245AbjCXDmV (ORCPT ); Thu, 23 Mar 2023 23:42:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60436 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229794AbjCXDmQ (ORCPT ); Thu, 23 Mar 2023 23:42:16 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 35E00211F8; Thu, 23 Mar 2023 20:42:14 -0700 (PDT) Received: from kwepemm600012.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4PjScP4L0xzbcCX; Fri, 24 Mar 2023 11:39:01 +0800 (CST) Received: from [10.174.178.220] (10.174.178.220) by kwepemm600012.china.huawei.com (7.193.23.74) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.21; Fri, 24 Mar 2023 11:42:10 +0800 Message-ID: <0a6fc4bd-82a1-3200-3061-4634531b5a63@huawei.com> Date: Fri, 24 Mar 2023 11:42:09 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH 0/5]scsi:scsi_debug: Add error injection for single device Content-Language: en-US To: John Garry , "James E . J . Bottomley" , "Martin K . Petersen" , Douglas Gilbert , , CC: , References: <20230323115601.178494-1-haowenchao2@huawei.com> <750a4b24-6122-6faa-fed4-25e3167ea376@oracle.com> From: "haowenchao (C)" In-Reply-To: <750a4b24-6122-6faa-fed4-25e3167ea376@oracle.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.178.220] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemm600012.china.huawei.com (7.193.23.74) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2023/3/24 0:25, John Garry wrote: > On 23/03/2023 13:13, haowenchao (C) wrote: >> On 2023/3/23 20:40, John Garry wrote: >>> On 23/03/2023 11:55, Wenchao Hao wrote: >>>> The original error injection mechanism was based on scsi_host which >>>> could not inject fault for a single SCSI device. >>>> >>>> This patchset provides the ability to inject errors for a single >>>> SCSI device. Now we supports inject timeout errors, queuecommand >>>> errors, and hostbyte, driverbyte, statusbyte, and sense data for >>>> specific SCSI Command. >>> >>> There is already a basic mechanism to generate errors - like timeouts - on "nth" command. Can you say why you want this new interface? What special scenarios are you trying to test/validate (which could not be achieved based on the current mechanism)? >>> >> >> I am testing a new error handle policy which is based on single scsi_device >> without set host to RECOVERY. So I need a method to generate errors for >> single SCSI devices. >> >> While we can not generate errors for single device with current mechanism >> because it is designed for host-wide error generation. >> >>> With this series we would have 2x methods to inject errors, which is less than ideal, and they seem to possibly conflict as well, e.g. I set timeout for nth command via current interface and then use the new interface to set timeout for some other cadence. What behavior to expect ...? >> >> I did not take this issue in consideration. I now assume the users would >> not use these 2 methods at same time. >> >> What's more, I don not know where to write the usage of this newly added >> interface, maybe we can explain these in doc? > > sysfs entries are described in Documentation/ABI, but please don't add elaborate programming interfaces in sysfs files (like in these patches) - a sysfs file should be just for reading or writing a single value > If sysfs is not recommended, what about proc? >> >>> >>> I'm not saying that I am a huge fan of the current inject mechanism, but at the very least you need to provide more justification for this series. >>>>> >>>> The first patch add an sysfs interface to add and inquiry single >>>> device's error injection info; the second patch defined how to remove >>>> an injection which has been added. The following 3 patches use the >>>> injection info and generate the related error type. >>>> >>>> Wenchao Hao (5): >>>>    scsi:scsi_debug: Add sysfs interface to manage scsi devices' error >>>>      injection >>>>    scsi:scsi_debug: Define grammar to remove added error injection >>>>    scsi:scsi_debug: timeout command if the error is injected >>>>    scsi:scsi_debug: Return failed value if the error is injected >>>>    scsi:scsi_debug: set command's result and sense data if the error is >>>>      injected >>>> >>>>   drivers/scsi/scsi_debug.c | 296 ++++++++++++++++++++++++++++++++++++++ >>>>   1 file changed, 296 insertions(+) >>>> >>> >>> >> >