Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754485AbcKIUf1 (ORCPT ); Wed, 9 Nov 2016 15:35:27 -0500 Received: from mail-yw0-f174.google.com ([209.85.161.174]:32912 "EHLO mail-yw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754459AbcKIUfZ (ORCPT ); Wed, 9 Nov 2016 15:35:25 -0500 MIME-Version: 1.0 In-Reply-To: References: <1478185120-5509-1-git-send-email-john.garry@huawei.com> From: Dan Williams Date: Wed, 9 Nov 2016 12:35:23 -0800 Message-ID: Subject: Re: [RFC PATCH] scsi: libsas: fix WARN on device removal To: John Garry Cc: "Martin K. Petersen" , jejb@linux.vnet.ibm.com, linux-scsi , john.garry2@mail.dcu.ie, linuxarm@huawei.com, "linux-kernel@vger.kernel.org" , lindar_liu@usish.com, jinpu.wang@profitbricks.com, Tejun Heo Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1466 Lines: 40 On Wed, Nov 9, 2016 at 11:09 AM, Dan Williams wrote: > On Wed, Nov 9, 2016 at 9:36 AM, John Garry wrote: >> On 09/11/2016 12:28, John Garry wrote: >>> >>> On 03/11/2016 14:58, John Garry wrote: >>>> >>>> The following patch introduces an annoying WARN >>>> when a device is removed from the SAS topology: >>>> [SCSI] libsas: prevent domain rediscovery competing with ata error >>>> handling >>>> >>> >>> Are there any views on this patch? I would have thought that the parties >>> who use the drivers based on libsas would be interested in fixing this >>> bug. >>> >> >> I should have added the before and after logs earlier, so the issue is >> illustrated. Now attached. When a 24-port expander is unplugged we get >6k >> lines of WARN on the console, lasting >30 seconds. Not nice. >> > > I might be mistaken, but this patch seems functionally identical to > this attempt: > > http://marc.info/?l=linux-scsi&m=143459794823595&w=2 > > i.e. it moves the port destruction to the workqueue and still suffers > from the flutter problem: > > http://marc.info/?l=linux-scsi&m=143801026028006&w=2 > http://marc.info/?l=linux-scsi&m=143801971131073&w=2 > > Perhaps we instead need to quiet this warning? > > http://marc.info/?l=linux-scsi&m=143802229932175&w=2 Alternatively we need a mechanism to cancel in-flight port shutdown requests when we start re-attaching devices before queued port destruction events have run.