From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756745AbZELPIw (ORCPT ); Tue, 12 May 2009 11:08:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752581AbZELPIk (ORCPT ); Tue, 12 May 2009 11:08:40 -0400 Received: from gw-ca.panasas.com ([209.116.51.66]:29962 "EHLO laguna.int.panasas.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752121AbZELPIi (ORCPT ); Tue, 12 May 2009 11:08:38 -0400 Message-ID: <4A0990E1.7080508@panasas.com> Date: Tue, 12 May 2009 18:08:17 +0300 From: Boaz Harrosh User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1b3pre) Gecko/20090315 Remi/3.0-0.b2.fc10.remi Thunderbird/3.0b2 MIME-Version: 1.0 To: FUJITA Tomonori CC: tj@kernel.org, axboe@kernel.dk, linux-kernel@vger.kernel.org, jeff@garzik.org, linux-ide@vger.kernel.org, James.Bottomley@HansenPartnership.com, linux-scsi@vger.kernel.org, bzolnier@gmail.com, petkovbb@googlemail.com, sshtylyov@ru.mvista.com, mike.miller@hp.com, Eric.Moore@lsi.com, stern@rowland.harvard.edu, zaitcev@redhat.com, Geert.Uytterhoeven@sonycom.com, sfr@canb.auug.org.au, grant.likely@secretlab.ca, paul.clements@steeleye.com, tim@cyberelk.net, jeremy@xensource.com, adrian@mcmen.demon.co.uk, oakad@yahoo.com, dwmw2@infradead.org, schwidefsky@de.ibm.com, ballabio_dario@emc.com, davem@davemloft.net, rusty@rustcorp.com.au, Markus.Lidel@shadowconnect.com, dgilbert@interlog.com, djwong@us.ibm.com Subject: Re: [PATCH 03/11] block: add rq->resid_len References: <4A080C9D.9000109@panasas.com> <20090511235852Z.fujita.tomonori@lab.ntt.co.jp> <4A093A34.3020101@panasas.com> <20090513000150H.fujita.tomonori@lab.ntt.co.jp> In-Reply-To: <20090513000150H.fujita.tomonori@lab.ntt.co.jp> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 12 May 2009 15:08:37.0874 (UTC) FILETIME=[86F3E520:01C9D313] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/12/2009 06:00 PM, FUJITA Tomonori wrote: > On Tue, 12 May 2009 11:58:28 +0300 > Boaz Harrosh wrote: > >> On 05/11/2009 05:59 PM, FUJITA Tomonori wrote: >>> On Mon, 11 May 2009 14:31:41 +0300 >>> Boaz Harrosh wrote: >>> >>>>>>> diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c >>>>>>> index 3da02e4..6605ec9 100644 >>>>>>> --- a/drivers/scsi/libsas/sas_expander.c >>>>>>> +++ b/drivers/scsi/libsas/sas_expander.c >>>>>>> @@ -1936,12 +1936,8 @@ int sas_smp_handler(struct Scsi_Host *shost, struct sas_rphy *rphy, >>>>>>> bio_data(rsp->bio), rsp->data_len); >>>>>>> if (ret > 0) { >>>>>>> /* positive number is the untransferred residual */ >>>>>>> - rsp->data_len = ret; >>>>>>> - req->data_len = 0; >>>>>>> + rsp->resid_len = ret; >>>>>>> ret = 0; >>>>>>> - } else if (ret == 0) { >>>>>>> - rsp->data_len = 0; >>>>>>> - req->data_len = 0; >>>>>>> } >>>>>>> >>>>>>> return ret; >>>>>> This is actually a bug fix, as well as a strait conversion >>>>> Can you elaborate a bit about the bug fix part? >>>>> >>>> Nothing big really, just that before (according to the comment), the theoretical >>>> negative case would be full-residual. and now it is zero (untouched). >>>> >>>> I know that in iscsi a negative residual is possible which means over-flow. That is: >>>> the target had more data to give then the buffer had space for. (which is not an error at all) >>> Hmm, iSCSI? This code is for SAS management Protocol. >>> >> I gave that as an example of what the scsi standard says about negative >> residual count return from the target. If SAS as sepecific and different >> meaning to negative residual, it should be noted and handled. > > Please read the code first. > > If sas_smp_handler() returns a negative value, a lld doesn't transfer > anything. The original code used full-residual. The original code is > fine. Your 'this is a bug fix' claim is wrong. We need to revert the > original behavior though. Please read my full reply, I said yes old code was better, but not good enough, error status must be returned also in this case. This code is already submitted are you sending a fix? Thanks Boaz