From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751913Ab2GZJVS (ORCPT ); Thu, 26 Jul 2012 05:21:18 -0400 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:49382 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751481Ab2GZJVQ (ORCPT ); Thu, 26 Jul 2012 05:21:16 -0400 Message-ID: <1343294472.3115.22.camel@dabdike> Subject: Re: [PATCH 1/2] virtio-scsi: fix parsing of hotplug/hot-unplug LUN number From: James Bottomley To: Paolo Bonzini Cc: linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org Date: Thu, 26 Jul 2012 13:21:12 +0400 In-Reply-To: <50110820.4040403@redhat.com> References: <1342454751-8950-1-git-send-email-pbonzini@redhat.com> <1342454751-8950-2-git-send-email-pbonzini@redhat.com> <1343292731.3115.17.camel@dabdike> <50110820.4040403@redhat.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2012-07-26 at 11:04 +0200, Paolo Bonzini wrote: > Il 26/07/2012 10:52, James Bottomley ha scritto: > >> > +static unsigned int virtscsi_get_lun(u8 *lun_bytes) > >> > +{ > >> > + unsigned int lun = (lun_bytes[2] << 8) | lun_bytes[3]; > >> > + return lun & 16383; > >> > +} > >> > + > > Why are you rolling your own incomplete version of scsilun_to_int here? > > Because scsilun_to_int does not do the AND, so it would have exactly the > same bug I'm fixing. It's not a bug ... it's the encoding. All the other devices use this too. Ideally we should have switched to 64 bit lun numbers for the encoding to be exact, but nothing so far has gone over 32 bits. If we don't encode the Address method as part of the lun number, we don't get the reverse transform right and the addressing often fails. That does mean that arrays that use address method=1 in REPORT LUNS have their lun numbers start at 16384. James