From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brian King Subject: Handling ordered tags Date: Mon, 28 Mar 2005 15:45:13 -0600 Message-ID: <42487AE9.4000904@us.ibm.com> Reply-To: brking@us.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from e5.ny.us.ibm.com ([32.97.182.145]:49614 "EHLO e5.ny.us.ibm.com") by vger.kernel.org with ESMTP id S262087AbVC1VpP (ORCPT ); Mon, 28 Mar 2005 16:45:15 -0500 Received: from d01relay04.pok.ibm.com (d01relay04.pok.ibm.com [9.56.227.236]) by e5.ny.us.ibm.com (8.12.11/8.12.11) with ESMTP id j2SLjEPO017347 for ; Mon, 28 Mar 2005 16:45:14 -0500 Received: from d01av01.pok.ibm.com (d01av01.pok.ibm.com [9.56.224.215]) by d01relay04.pok.ibm.com (8.12.10/NCO/VER6.6) with ESMTP id j2SLjEW5234718 for ; Mon, 28 Mar 2005 16:45:14 -0500 Received: from d01av01.pok.ibm.com (loopback [127.0.0.1]) by d01av01.pok.ibm.com (8.12.11/8.12.11) with ESMTP id j2SLjE2s001886 for ; Mon, 28 Mar 2005 16:45:14 -0500 Received: from [9.10.86.27] (kaled.rchland.ibm.com [9.10.86.27]) by d01av01.pok.ibm.com (8.12.11/8.12.11) with ESMTP id j2SLjDwB001825 for ; Mon, 28 Mar 2005 16:45:14 -0500 Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: linux-scsi@vger.kernel.org I'm trying to understand all the implications of allowing ordered tags for a SCSI LLD, especially when running QERR=0 with autosense and no ACA. Are any of these problems a concern given how ordered tags are used in Linux? 1. If an ordered tag is sent and a previously sent simple tagged op completes with a failure, the ordered tag will still execute. 2. If an ordered tag is sent and completes with a failure, any simple tags sent after it will execute. I guess my bigger question is, are there any additional requirements on an LLD in order for it to support ordered tags? Can the LLD send back responses in any order? Thanks -- Brian King eServer Storage I/O IBM Linux Technology Center