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=-5.5 required=3.0 tests=BAYES_00,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 D6CD0C433FE for ; Tue, 8 Dec 2020 11:24:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 87B5B23A1D for ; Tue, 8 Dec 2020 11:24:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729137AbgLHLXt (ORCPT ); Tue, 8 Dec 2020 06:23:49 -0500 Received: from mail-ej1-f67.google.com ([209.85.218.67]:47075 "EHLO mail-ej1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726226AbgLHLXt (ORCPT ); Tue, 8 Dec 2020 06:23:49 -0500 Received: by mail-ej1-f67.google.com with SMTP id bo9so23988592ejb.13 for ; Tue, 08 Dec 2020 03:23:32 -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=/vQIR8cILfXFY8rOgnw9V9vTbP76cwtxK2fEgl/bYiA=; b=o945JsLOiCQ1LCDPvDCiHcQmIeppXrVmBS95NsM1QzPr3wYYeKQb+UXQj9zVQeI/Yo BNwLQDP0ok/jUEXUB2kvZ27TkkGxL/BzOPJQaRZGtCo1gOsrrf4TtljX1sF8/JbZzfW+ r3yQQpYscqh+ignl4hqv9j0OHFColtvf2mCDZWG7Bp+nFs6Wt0hsJnV/n6ZyPzTwP5WF 2cJdFcUF1LvCxSwwwa3jcMMwre1WRTvUu2hyGvPzGvBL1K37TjXSY/KPeOhwG5wvG29I OxSGK1E7EvThZjcHDbjgrCQW7U7Pc/N2neDWDo6szV//HCvhP60qkr3SdtbZlb+tsFof T3rw== X-Gm-Message-State: AOAM5318qlNiiTObYjidS1O04j6xcaBaqLYidVzn0xbsBeiZEidUqvYW sBx7bepJoxM9wHTNqlFPbTJVagnyh8iZNA== X-Google-Smtp-Source: ABdhPJz1q4ahsSdr2WBU7qTuMJWyp18EfLFBlJ7kK5b8cVJwtgj05uA2lYGuY8aFxYd5y5a5yrHNDQ== X-Received: by 2002:a17:907:444f:: with SMTP id on23mr23201089ejb.300.1607426586733; Tue, 08 Dec 2020 03:23:06 -0800 (PST) Received: from ?IPv6:2a0b:e7c0:0:107::49? ([2a0b:e7c0:0:107::49]) by smtp.gmail.com with ESMTPSA id qn4sm4476420ejb.50.2020.12.08.03.23.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 08 Dec 2020 03:23:05 -0800 (PST) Subject: Re: [PATCH] tty: Remove dead termiox code To: Christoph Hellwig Cc: Greg Kroah-Hartman , Jann Horn , linux-kernel@vger.kernel.org References: <20201203020331.2394754-1-jannh@google.com> <5cca5126-60ba-d123-0f7d-47fdbac4c4db@kernel.org> <93834a92-b342-aaee-c400-2883d5df0cdc@kernel.org> <20201208111312.GA27425@infradead.org> From: Jiri Slaby Message-ID: Date: Tue, 8 Dec 2020 12:23:05 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: <20201208111312.GA27425@infradead.org> Content-Type: text/plain; charset=iso-8859-2; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08. 12. 20, 12:13, Christoph Hellwig wrote: > On Fri, Dec 04, 2020 at 09:20:39AM +0100, Jiri Slaby wrote: >>>>> Delete this dead code; but leave the definition of struct termiox in the >>>>> UAPI headers intact. >>>> >>>> I am thinking -- can/should we mark the structure as deprecated so that >>>> userspace stops using it eventually? >>> >>> If it doesn't do anything, how can userspace even use it today? :) >> >> Well, right. I am in favor to remove it, BUT: what if someone tries that >> ioctl and bails out if EINVAL is returned. I mean: if they define a local >> var of that struct type and pass it to the ioctl, we would break the build >> by removing the struct completely. Even if the code didn't do anything >> useful, it still could be built. So is this very potential breakage OK? > > Um, we do guarantee a stable ABI. We have never guaranteed that all old > crappy code will continue to compile, although we avoid gratious > breakage. And assuming there ever was code using termiox (which I'm not > sure about to start with) it will surely have some form of feature > check, and I think we are better off with that feature check not > detecting the presence as that would be completely pointless. > > Or in short: by keeping the uapi definition we do userspace software a > disfavor. OK, even better. I will remove it once I get to it (if noone beats me to it, of course). thanks, -- js suse labs