From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753994AbbJNNzJ (ORCPT ); Wed, 14 Oct 2015 09:55:09 -0400 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:47600 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753591AbbJNNzH (ORCPT ); Wed, 14 Oct 2015 09:55:07 -0400 Message-ID: <1444830904.2220.28.camel@HansenPartnership.com> Subject: Re: [PATCHv4 1/1] SCSI: hosts: update to use ida_simple for host_no management From: James Bottomley To: Lee Duncan Cc: linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, Tejun Heo , Hannes Reinecke , Johannes Thumshirn , Christoph Hellwig Date: Wed, 14 Oct 2015 06:55:04 -0700 In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.11 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2015-10-07 at 16:51 -0700, Lee Duncan wrote: > Update the SCSI hosts module to use the ida_simple*() routines > to manage its host_no index instead of an ATOMIC integer. This > means that the SCSI host number will now be reclaimable. OK, but why would we want to do this? We do it for sd because our minor space for the device nodes is very constrained, so packing is essential. For HBAs, there's no device space density to worry about, they're largely statically allocated at boot time and not reusing the numbers allows easy extraction of hotplug items for the logs (quite useful for USB) because each separate hotplug has a separate and monotonically increasing host number. James