From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754710Ab3AYXrU (ORCPT ); Fri, 25 Jan 2013 18:47:20 -0500 Received: from mail-da0-f50.google.com ([209.85.210.50]:60007 "EHLO mail-da0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753728Ab3AYXrT (ORCPT ); Fri, 25 Jan 2013 18:47:19 -0500 Date: Fri, 25 Jan 2013 15:47:14 -0800 From: Tejun Heo To: Paolo Bonzini Cc: linux-kernel@vger.kernel.org, pmatouse@redhat.com, "James E.J. Bottomley" , linux-scsi@kernel.org, Jens Axboe Subject: Re: [PATCH 06/13] sg_io: whitelist a few more commands for multimedia devices Message-ID: <20130125234714.GR3081@htj.dyndns.org> References: <20130125170434.GC3081@htj.dyndns.org> <5102BDD4.2020501@redhat.com> <20130125172805.GG3081@htj.dyndns.org> <5102C780.3090402@redhat.com> <20130125181326.GK3081@htj.dyndns.org> <5102D353.8010305@redhat.com> <20130125190154.GM3081@htj.dyndns.org> <5103080A.4090803@redhat.com> <20130125224159.GQ3081@htj.dyndns.org> <51031614.8000609@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <51031614.8000609@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Paolo. On Sat, Jan 26, 2013 at 12:32:36AM +0100, Paolo Bonzini wrote: > If I make a whitelist with all the commands that Linux sends, I'll have > many new commands in the whitelist and no old commands. The new > commands didn't exist when old drives were sold, so they are "dangerous" > in your opinion. At that point I might as well keep the whitelist > empty, no? Let's not go to extremes. It's not about theoretic correctness. It's about how to appraoch a possibly messy practical problem. To me, it seems natural to be conservative on this and add what's being acitvely used, which as a bonus will also give us at least some chance of evaluating what we have and why later on if it ever needs to be changed. I'm just not comfortable with adding a bunch of commands by simply scanning the specs. Let's at least have some backing data and justification for exposing new ones. I really don't think that's too much to ask. Start with minimal set. Grow it as needed. We can always grow but the other direction is much harder. Thanks. -- tejun