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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 EB57DC433DB for ; Mon, 4 Jan 2021 17:44:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B3B0B206B2 for ; Mon, 4 Jan 2021 17:44:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728010AbhADRob (ORCPT ); Mon, 4 Jan 2021 12:44:31 -0500 Received: from mail-pg1-f172.google.com ([209.85.215.172]:44032 "EHLO mail-pg1-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727986AbhADRoa (ORCPT ); Mon, 4 Jan 2021 12:44:30 -0500 Received: by mail-pg1-f172.google.com with SMTP id p18so19486095pgm.11; Mon, 04 Jan 2021 09:44:14 -0800 (PST) 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=W41s4SpHuFxfP2VmE7HCI4KFVMEE3WKx0iXTMwP7vnM=; b=m9QJ1edukeXN241rEKi8gvQhMIRvwBhPUC7zH/aAtYY+56R9/lYmoGzvdNvs/lmklP vdv9cAuBHMNOUwxlMhyjvvh8rvRRWQk11YxRUPal6o9TINKZCQSfjJP+vFaozUE5ntHz HUzhxPWN+BFIEseiJt0Rf8yD2GPCNM0Q553RrLiTbNuvOk8P1J9P6XVURet1GSI5xKVh 2hUmJWsWDJiiHvXl1ccj+A1/ylb63H3EirNgDrQB2kTPiw3zKtg7muJXtLtTwEXzRILY R+P5UIUOcodnRdxbrSroIrLFFh+yZmjyl3Of8yuX66pJMuvjhAMA8oj55xDh94tUF387 sNyw== X-Gm-Message-State: AOAM5331N0qVoolmrUyNx8+EsWp7af8fljZe3/WaJ00nadkn82655bt2 s6beDBZQwpdepzCcP42xngg= X-Google-Smtp-Source: ABdhPJwKTIkHd9jD106iNYsMCjlbG9ke8DsYiuUgJzn38bv0xFujzmC1vyllUPjkZAgfvXQ07hPHdg== X-Received: by 2002:a63:c1e:: with SMTP id b30mr71096758pgl.72.1609782229216; Mon, 04 Jan 2021 09:43:49 -0800 (PST) Received: from [192.168.3.217] (c-73-241-217-19.hsd1.ca.comcast.net. [73.241.217.19]) by smtp.gmail.com with ESMTPSA id b4sm10376pju.33.2021.01.04.09.43.47 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 04 Jan 2021 09:43:48 -0800 (PST) Subject: Re: [PATCH] scsi: target/sbp: remove firewire SBP target driver To: Finn Thain Cc: Chris Boot , linuxppc-dev@lists.ozlabs.org, target-devel@vger.kernel.org, linux-scsi@vger.kernel.org, linux1394-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, Chuhong Yuan , "Martin K . Petersen" , Nicholas Bellinger , Stefan Richter References: <01020172acd3d10f-3964f076-a820-43fc-9494-3f3946e9b7b5-000000@eu-west-1.amazonses.com> <7ad14946-5c25-fc49-1e48-72d37a607832@boo.tc> <8da0c285-d707-a3d2-063e-472af5cc560f@boo.tc> <8cbab988-fba7-8e27-7faf-9f7aa36ca235@acm.org> From: Bart Van Assche Message-ID: Date: Mon, 4 Jan 2021 09:43:46 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/16/20 7:07 PM, Finn Thain wrote: > On Tue, 16 Jun 2020, Bart Van Assche wrote: >> As far as I know the sbp driver only has had one user ever and that user >> is no longer user the sbp driver. > > So, you estimate the userbase at zero. Can you give a confidence level? > Actual measurement is hard because when end users encounter breakage, they > look for quick workarounds before they undertake post mortem, log > collection, bug reporting, mailing list discussions, analysis etc. (replying to an e-mail from six months ago) Hi Finn, I am confident that my estimate is an accurate estimate since I have not seen any sbp support requests, sbp bug reports nor any sbp bug fixes since the sbp target driver has been accepted upstream. > Here's a different question: "Why remove it from the kernel tree?" > > If maintaining this code is a burden, is it not the kind of tax that all > developers/users pay to all developers/users? Does this driver impose an > unreasonably high burden for some reason? Yes. If anyone wants to change the interface between SCSI target core and SCSI target drivers, all target drivers, including the sbp and FCoE target driver have to be retested. In other words, keeping unused target drivers inside the kernel tree involves a significant maintenance burden for anyone who wants to modify the interface between the SCSI target core and SCSI target drivers. Additionally, there is a good alternative available for the sbp driver. Every system I know of that is equipped with a Firewire port also has an Ethernet port. So users who want to provide SCSI target functionality on such systems can use any SCSI transport protocol that is compatible with Ethernet (iSCSI, iSER over soft-RoCE, SRP over soft-RoCE, ...). Thanks, Bart. 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[73.241.217.19]) by smtp.gmail.com with ESMTPSA id b4sm10376pju.33.2021.01.04.09.43.47 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 04 Jan 2021 09:43:48 -0800 (PST) Subject: Re: [PATCH] scsi: target/sbp: remove firewire SBP target driver To: Finn Thain References: <01020172acd3d10f-3964f076-a820-43fc-9494-3f3946e9b7b5-000000@eu-west-1.amazonses.com> <7ad14946-5c25-fc49-1e48-72d37a607832@boo.tc> <8da0c285-d707-a3d2-063e-472af5cc560f@boo.tc> <8cbab988-fba7-8e27-7faf-9f7aa36ca235@acm.org> From: Bart Van Assche Message-ID: Date: Mon, 4 Jan 2021 09:43:46 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Martin K . Petersen" , linux-scsi@vger.kernel.org, Chuhong Yuan , linux-kernel@vger.kernel.org, Nicholas Bellinger , target-devel@vger.kernel.org, Chris Boot , linux1394-devel@lists.sourceforge.net, linuxppc-dev@lists.ozlabs.org, Stefan Richter Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 6/16/20 7:07 PM, Finn Thain wrote: > On Tue, 16 Jun 2020, Bart Van Assche wrote: >> As far as I know the sbp driver only has had one user ever and that user >> is no longer user the sbp driver. > > So, you estimate the userbase at zero. Can you give a confidence level? > Actual measurement is hard because when end users encounter breakage, they > look for quick workarounds before they undertake post mortem, log > collection, bug reporting, mailing list discussions, analysis etc. (replying to an e-mail from six months ago) Hi Finn, I am confident that my estimate is an accurate estimate since I have not seen any sbp support requests, sbp bug reports nor any sbp bug fixes since the sbp target driver has been accepted upstream. > Here's a different question: "Why remove it from the kernel tree?" > > If maintaining this code is a burden, is it not the kind of tax that all > developers/users pay to all developers/users? Does this driver impose an > unreasonably high burden for some reason? Yes. If anyone wants to change the interface between SCSI target core and SCSI target drivers, all target drivers, including the sbp and FCoE target driver have to be retested. In other words, keeping unused target drivers inside the kernel tree involves a significant maintenance burden for anyone who wants to modify the interface between the SCSI target core and SCSI target drivers. Additionally, there is a good alternative available for the sbp driver. Every system I know of that is equipped with a Firewire port also has an Ethernet port. So users who want to provide SCSI target functionality on such systems can use any SCSI transport protocol that is compatible with Ethernet (iSCSI, iSER over soft-RoCE, SRP over soft-RoCE, ...). Thanks, Bart.