From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752786AbaILTuD (ORCPT ); Fri, 12 Sep 2014 15:50:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:3284 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752497AbaILTuA (ORCPT ); Fri, 12 Sep 2014 15:50:00 -0400 Message-ID: <54134E50.6040805@redhat.com> Date: Fri, 12 Sep 2014 21:49:36 +0200 From: Hans de Goede User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0 MIME-Version: 1.0 To: Christoph Hellwig CC: linux-usb , SCSI development list , Linux Kernel Mailing List Subject: Re: [REGRESSION 3.17] scsi (uas) disks no longer using tagged command queuing References: <540EC52C.3000804@redhat.com> <20140909152730.GA17882@infradead.org> <540FFBF4.9090001@redhat.com> <20140910154535.GA5102@infradead.org> <541172E9.8070309@redhat.com> <20140911161331.GA24488@infradead.org> In-Reply-To: <20140911161331.GA24488@infradead.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 09/11/2014 06:13 PM, Christoph Hellwig wrote: > On Thu, Sep 11, 2014 at 12:01:13PM +0200, Hans de Goede wrote: >>> So we're initializing the tag map, but scsi_activate_tcq doesn't pick it >>> up. I can't really come up with a good explanation for it, but there >>> even without that there is an elephant in the room: as part of the >>> scsi-mq series I moved the bqt field used for this into a union with the >>> new blk_mq_tag_set. Below is a patch to get rid of that union, can you >>> try if that fixes it? >> >> Unfortunately that does not fix it :| > > Alright, I guess we need the big bisect hammer unfortunately. > > We should be able to start with trying the first and last commit > of the big SCSI merge: > > start: fcc95a763444017288b318d48367098850c23c0d > end: c21a2c1a4973c8dde32557970fdb44eaa9489aeb The bisect points to: [hans@shalem linux]$ git bisect bad Bisecting: 0 revisions left to test after this (roughly 0 steps) [d285203cf647d7c97db3a1c33794315c9008593f] scsi: add support for a blk-mq based I/O path. I've double checked that that commit is bad, and one commit earlier in the history is good, so that really is the one. I've tried again to fix the union thing you spotted, which is introduced by that commit, and again it does not help. I've taken a quick look at the commit, and my guess with be this has something to do with the changes surrounding __scsi_alloc_queue . Regards, Hans