From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751763AbaIJHVv (ORCPT ); Wed, 10 Sep 2014 03:21:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43040 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751372AbaIJHVt (ORCPT ); Wed, 10 Sep 2014 03:21:49 -0400 Message-ID: <540FFBF4.9090001@redhat.com> Date: Wed, 10 Sep 2014 09:21:24 +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> In-Reply-To: <20140909152730.GA17882@infradead.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 09/09/2014 05:27 PM, Christoph Hellwig wrote: > On Tue, Sep 09, 2014 at 11:15:24AM +0200, Hans de Goede wrote: >> Taking the uas.c file from 3.17, and building it for 3.16 restores >> the use of tcq (debugged by adding a printk blk_rq_tagged + request->tag). >> >> So either uas is doing something wrong which happened to work in >> 3.16, or something has broken in 3.17. >> >> I've already added debug printk-s of scsi_device->tagged_supported, >> queue_depth, ordered_tags and simple_tags and those all look good >> (1, 29, 1, 1). >> >> I've also tried setting disable_blk_mq and that does not help. >> >> Any hints to help debugging this further (other then a bisect) are >> appreciated. If no-one has any smart ideas I guess I'll end up doing >> a full bisect. > > scsi-mq isn't enabled by default, so setting disable_blk_mq should > indeed not make a difference. > > One interesting thing with uas is that it uses scsi_init_shared_tag_map, > which only few drivers do. > > Can you apply a debug patch like the one below and see if that helps to > poinpoint down the issue? I've applied the patch, this results in the following new dmesg output when using uas: [ 120.602632] initialized host-wide tag map! Thank you for looking into this. Regards, Hans