From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Subject: Re: Regarding ordered-tag support. Date: Thu, 09 Feb 2006 02:18:28 +0900 Message-ID: <43EA27E4.9080105@gmail.com> References: <43E99248.7090505@gmail.com> <1139413766.3003.19.camel@mulgrave.il.steeleye.com> <43EA17E6.4000800@gmail.com> <43EA1B75.40008@emulex.com> <43EA2313.9030506@gmail.com> <1139418451.3003.37.camel@mulgrave.il.steeleye.com> Mime-Version: 1.0 Content-Type: text/plain; charset=EUC-KR Content-Transfer-Encoding: 7bit Return-path: Received: from zproxy.gmail.com ([64.233.162.206]:32478 "EHLO zproxy.gmail.com") by vger.kernel.org with ESMTP id S1030338AbWBHRSe (ORCPT ); Wed, 8 Feb 2006 12:18:34 -0500 Received: by zproxy.gmail.com with SMTP id 14so1728789nzn for ; Wed, 08 Feb 2006 09:18:33 -0800 (PST) In-Reply-To: <1139418451.3003.37.camel@mulgrave.il.steeleye.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: James.Smart@Emulex.Com, SCSI Mailing List James Bottomley wrote: > On Thu, 2006-02-09 at 01:57 +0900, Tejun wrote: > >>I intentionally wrote 'driver' because if a SCSI device determines that >>it's busy, it would report via CHECK CONDITION. Depending on QErr, the >>whole task set will be terminated, and such case falls into EH >>requeueing case (would require changes in scsi_softirq though). > > No, it wouldn't. BUSY is a SPI Message (deprecated on non-SPI > transports) and QUEUE_FULL is a status return. The device is entitled > to think of the transaction as logically complete (and not impacting > error recovery) after either of these returns. I see. I'll dig docs. >>>You're making the assumption that you can set QErr... It's under device control. >> >>Was it ro field? Didn't know that. I will check it tomorrow. If a >>device doesn't abort whole taskset, we just can't use ordered-tag for >>barriers. > > > His point is that it's a field in the mode page of a device. Some > devices only have read only mode pages ... still more may not act on > this field correctly even if set. Basically it's opening a can of > worms. Yeah, I kind of doubt whether hardware vendors would implement and test all the options and features whene I read SCSI specs. Considering how many ATA drives have faulty firmware... Anyways, it seems ordered-tag support should be left alone for the time being. Sad. :-( Thanks a lot. -- tejun