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 9E1D4C433FE for ; Sat, 9 Apr 2022 04:26:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240782AbiDIE2e (ORCPT ); Sat, 9 Apr 2022 00:28:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58584 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240861AbiDIE1r (ORCPT ); Sat, 9 Apr 2022 00:27:47 -0400 Received: from nksmu.kylinos.cn (mailgw.kylinos.cn [123.150.8.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 845412E1627; Fri, 8 Apr 2022 21:25:39 -0700 (PDT) X-UUID: ba5dd6ec4e194e7e858000d3602be3bc-20220409 X-CPASD-INFO: dfdc728120ed4e33ae419e466acbcd6f@rbaeg2RkZmFeUKewg6h-bYGWZGFpkVS FeJuDkpGUYoaVhH5xTWVlZ15UfYBqVWVbZV9ZenRqUmFeaFxTi3akdmpQYIRkXW10qrWmnVdiZmE= X-CLOUD-ID: dfdc728120ed4e33ae419e466acbcd6f X-CPASD-SUMMARY: SIP:-1,APTIP:-2.0,KEY:0.0,FROMBLOCK:1,OB:0.0,URL:0.6,TVAL:179 .0,ESV:0.0,ECOM:0.0,ML:0.0,FD:0.0,CUTS:110.0,IP:-2.0,MAL:-5.0,PHF:0.0,PHC:0.0 ,SPF:4.0,EDMS:-5,IPLABEL:-2.0,FROMTO:0,AD:0,FFOB:0.0,CFOB:0.0,SPC:0,SIG:-5,AU F:10,DUF:36647,ACD:248,DCD:350,SL:0,EISP:0,AG:0,CFC:0.324,CFSR:0.2,UAT:1,RAF: 2,IMG:-5.0,DFA:0,DTA:0,IBL:-2.0,ADI:-5,SBL:0,REDM:0,REIP:0,ESB:0,ATTNUM:0,EAF :0,CID:-5.0,VERSION:2.3.17 X-CPASD-ID: ba5dd6ec4e194e7e858000d3602be3bc-20220409 X-CPASD-BLOCK: 1000 X-CPASD-STAGE: 1 X-UUID: ba5dd6ec4e194e7e858000d3602be3bc-20220409 X-User: lienze@kylinos.cn Received: from asus [(61.48.215.124)] by nksmu.kylinos.cn (envelope-from ) (Generic MTA) with ESMTP id 1212242366; Sat, 09 Apr 2022 12:24:25 +0800 Date: Sat, 9 Apr 2022 12:25:30 +0800 From: Enze Li To: Jens Axboe Cc: phil@philpotter.co.uk, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org Subject: Re: [PATCH] cdrom: do not print info list when there is no cdrom device Message-ID: <20220409122530.60353fcd@asus> In-Reply-To: <25390602-cfa0-dba3-bfbc-a35ed6b44bcf@kernel.dk> References: <20220408084221.1681592-1-lienze@kylinos.cn> <25390602-cfa0-dba3-bfbc-a35ed6b44bcf@kernel.dk> X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-suse-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 8 Apr 2022 06:34:04 -0600 Jens Axboe wrote: > On 4/8/22 2:42 AM, Enze Li wrote: > > There is no need to print a list of cdrom entries with blank info > > when no cdrom device exists. With this patch applied, we get: > > > > ================================================ > > $ cat /proc/sys/dev/cdrom/info > > CD-ROM information, Id:cdrom.c 3.20 2003/12/17 > > > > No device found. > > > > ================================================ Hi Jens, Thanks for your review. > > And what did we get before? Without the patch, we get: ================================================ $ cat /proc/sys/dev/cdrom/info CD-ROM information, Id: cdrom.c 3.20 2003/12/17 drive name: drive speed: drive # of slots: Can close tray: Can open tray: Can lock tray: Can change speed: Can select disk: Can read multisession: Can read MCN: Reports media changed: Can play audio: Can write CD-R: Can write CD-RW: Can read DVD: Can write DVD-R: Can write DVD-RAM: Can read MRW: Can write MRW: Can write RAM: ================================================ > > Will this potentially break applications that parse it? > I dunno, is there any way to confirm this thing? And if this is really a possibility, does it mean that we cannot make changes? BTW, could you pls help review the following patch? I forgot to cc you and linux-block@list. :) https://lore.kernel.org/lkml/20220406090337.1116708-1-lienze@kylinos.cn/ Thanks, Enze