From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chandra Seetharaman Subject: Re: [PATCH 1/3] scsi_dh: Add modalias support for SCSI targets Date: Wed, 15 Apr 2009 14:52:43 -0700 Message-ID: <1239832363.1196.5.camel@chandra-ubuntu> References: <20090318013615.26548.36303.sendpatchset@chandra-ubuntu> <20090318013621.26548.10529.sendpatchset@chandra-ubuntu> <1237403902.14147.25.camel@chandra-ubuntu> <1237488880.26341.15.camel@chandra-ubuntu> <49C3DF49.8050408@redhat.com> <1237846429.14853.6.camel@chandra-ubuntu> <1238798590.20924.0.camel@chandra-ubuntu> <1239137973.29492.12.camel@mulgrave> <49DCBDE6.5000806@redhat.com> Reply-To: sekharan@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from e31.co.us.ibm.com ([32.97.110.149]:45000 "EHLO e31.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750925AbZDOVwR (ORCPT ); Wed, 15 Apr 2009 17:52:17 -0400 Received: from d03relay04.boulder.ibm.com (d03relay04.boulder.ibm.com [9.17.195.106]) by e31.co.us.ibm.com (8.13.1/8.13.1) with ESMTP id n3FLmxak006031 for ; Wed, 15 Apr 2009 15:48:59 -0600 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay04.boulder.ibm.com (8.13.8/8.13.8/NCO v9.2) with ESMTP id n3FLqFIu210132 for ; Wed, 15 Apr 2009 15:52:16 -0600 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n3FLqENA011386 for ; Wed, 15 Apr 2009 15:52:15 -0600 In-Reply-To: <49DCBDE6.5000806@redhat.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: Kay Sievers , linux-scsi@vger.kernel.org, michaelc@cs.wisc.edu, Peter Jones , Hannes Reinecke Hi James, Are your concerns answered ? Hannes, Kay, Is the description related to bus notify BIND DEVICE issue clear now ? Please respond :) chandra On Wed, 2009-04-08 at 11:08 -0400, Peter Jones wrote: > On 04/07/2009 04:59 PM, James Bottomley wrote: > > On Fri, 2009-04-03 at 15:43 -0700, Chandra Seetharaman wrote: > >> Hi James, > >> > >> Do you still have any concerns (after Peter's response) ? > > > > Yes, the basic concerns still remain: > > > > 1. You're forcing autoload now even if the user isn't running > > dm ... this is going to cause problems with non-dm based path > > handlers > > (Chandra covered this pretty well, so I'll leave it be.) > > > 2. autoloading in this fashion is essentially trying to work around > > a problem in the initrd tools. The kernel isn't the right place > > to implement the fix. > > This seems backwards to me. It's not trying to work around a problem > in the initrd tools; it's trying to avoid creating one by making this > subsystem unlike others. > > The point of having modaliases is to allow the kernel to announce that it's > got a hardware device and notify the userland that appropriate modules should > be loaded. That's exactly what we've done here. What we're trying to avoid > in the initrd tools is having to have a special handler for this subsystem; > instead, we'd much rather use the generic mechanism that already exists for > this purpose. > > > The risks of this approach seem very high, and the rewards pretty small. > > Can you please explain what the high risks you're thinking of are? I'm not > clear on what undesirable behavior you expect to occur. > > The reward is that scsi targets behave exactly like most other types of > hardware and kernel modules in this regard, without having to write special > probing for this subsystem in the userland and special handling for loading > these modules. That's a pretty big win for maintainability. >