Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753304AbYFSUWx (ORCPT ); Thu, 19 Jun 2008 16:22:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750950AbYFSUWo (ORCPT ); Thu, 19 Jun 2008 16:22:44 -0400 Received: from palinux.external.hp.com ([192.25.206.14]:38962 "EHLO mail.parisc-linux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750834AbYFSUWn (ORCPT ); Thu, 19 Jun 2008 16:22:43 -0400 Date: Thu, 19 Jun 2008 14:22:26 -0600 From: Matthew Wilcox To: Stefan Richter Cc: Pekka J Enberg , Alan Stern , linux-kernel@vger.kernel.org, dsd@gentoo.org, mdharm-usb@one-eyed-alien.net, linux-usb@vger.kernel.org, vegardno@ifi.uio.no, James.Bottomley@HansenPartnership.com, linux-scsi@vger.kernel.org, Greg KH Subject: Re: [RFC/PATCH] usb-storage: wait for device scanning before mounting root Message-ID: <20080619202226.GP4392@parisc-linux.org> References: <48118DDD.8010507@s5r6.in-berlin.de> <20080425091122.GA14990@parisc-linux.org> <20080619182310.GA30833@parisc-linux.org> <485AA7EA.6080105@s5r6.in-berlin.de> <20080619185419.GN4392@parisc-linux.org> <485AB95E.5070609@s5r6.in-berlin.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <485AB95E.5070609@s5r6.in-berlin.de> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1915 Lines: 40 On Thu, Jun 19, 2008 at 09:54:06PM +0200, Stefan Richter wrote: > [...] > > The mail that I just pinged described a way to enhance the > > API -- letting you tell scsi "I've started scanning, save me a place in > > the queue" and "I've finished scanning, hook me up". > > When would be the right time to say "I've started scanning"? SCSI > transport driver initialization? Or end of USB/FireWire/... HCD > registration? You would need to call it before you could attempt to register any devices. So fairly early on in the initialisation of sbp2/usb-storage. > When to say "I've finished scanning"? --- I think the answer is: When > (a) probing of a configurable number of SCSI targets or logical units > was finished or (b) a configurable timeout occurs, whatever of the two > happens first. > > (Explanation, if one is necessary: SCSI targets may pop out of the > woods any time; it is impossible to say "from this moment on there won't > show up any new ones anymore". This is just as true for cold boot and > warm boot as it is for subsequent operation.) Yes, I do see the problem. There's no way the SCSI core can know when a driver has finished scanning, so I've punted to the driver to set its own timeout here. I know that new devices really can show up at any time, but I think it's reasonable to say that if a machine is booted with the same configuration as last time, the drives should show up with the same names. -- Intel are signing my paycheques ... these opinions are still mine "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step." -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/