From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brian King Subject: Re: eh_abort_handler and calling scsi_done Date: Wed, 25 Mar 2009 08:52:50 -0500 Message-ID: <49CA3732.2060508@linux.vnet.ibm.com> References: <20090324114137.GA8616@schmichrtp.de.ibm.com> <49C8E055.2060108@linux.vnet.ibm.com> <20090324174609.GA13556@linux.vnet.ibm.com> <20090325085235.GA4214@schmichrtp.de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from e35.co.us.ibm.com ([32.97.110.153]:37460 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762108AbZCYNww (ORCPT ); Wed, 25 Mar 2009 09:52:52 -0400 Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e35.co.us.ibm.com (8.13.1/8.13.1) with ESMTP id n2PDmAhD020556 for ; Wed, 25 Mar 2009 07:48:10 -0600 Received: from d03av04.boulder.ibm.com (d03av04.boulder.ibm.com [9.17.195.170]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v9.2) with ESMTP id n2PDqgVJ054794 for ; Wed, 25 Mar 2009 07:52:43 -0600 Received: from d03av04.boulder.ibm.com (loopback [127.0.0.1]) by d03av04.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n2PDqbQe016089 for ; Wed, 25 Mar 2009 07:52:38 -0600 In-Reply-To: <20090325085235.GA4214@schmichrtp.de.ibm.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Christof Schmitt Cc: Mike Anderson , linux-scsi@vger.kernel.org Christof Schmitt wrote: > On Tue, Mar 24, 2009 at 10:46:09AM -0700, Mike Anderson wrote: >> Brian King wrote: >>> Your assessment sounds correct to me. The other caveat to note is that >>> if for some reason in your eh_abort_handler you don't think the command >>> is still outstanding, you should return SUCCESS for this as well. >>> >>> -Brian >>> >>> Christof Schmitt wrote: >>>> I am investigating what is required from a LLD when SCSI commands time >>>> out and the SCSI EH calls the eh_abort_handler. The documentation in >>>> scsi_eh.txt states: >>>> >>>> <> >>>> >>>> This action is taken for each timed out command. >>>> hostt->eh_abort_handler() is invoked for each scmd. The >>>> handler returns SUCCESS if it has succeeded to make LLDD and >>>> all related hardware forget about the scmd. >>>> >>>> From this and from looking at the code, i would conclude: >>>> >>>> 1) If the LLD returns FAILED from the eh_abort_handler, then the >>>> command is still allowed to be active in the LLD and the LLD can >>>> call scsi_done any time later (probably latest when the >>>> eh_host_reset_handler flushes everything that is still pending). >>>> >>>> 2) While the abort is pending, but before returning SUCCESS from >>>> eh_abort_handler, the LLD can still call scsi_done for the SCSI >>>> command to be aborted (the SCSI command might be returned with a >>>> status "aborted" if the abort succeeds, or "good" if it was >>>> completed just before the abort reached the storage system). >>>> >> In cases 1 and 2 above calling scsi_done can be done but will cause >> the request to be stopped in blk_complete_request >> (scsi_done->blk_complete_request) as the timed out handler has >> already taken ownership of the command. > > I am not too familiar with the blk completion handling. Would calling > scsi_done for the cases above cause any problems? If there are reasons > not to call scsi_done here, then this could be mentioned in the scsi > documentation file. No. There is no requirement to call scsi_done for aborted commands, but there is also no harm in doing so. -Brian -- Brian King Linux on Power Virtualization IBM Linux Technology Center