From mboxrd@z Thu Jan 1 00:00:00 1970 From: FUJITA Tomonori Subject: Re: [PATCH 6/9] tgt: convert ibmvstgt and libsrp to use scsi_data_buffer Date: Sun, 9 Sep 2007 23:38:55 +0900 Message-ID: <20070909054929C.tomof@acm.org> References: <46E3C6F3.6020506@panasas.com> <20070909045722P.tomof@acm.org> <46E40319.4030704@panasas.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Received: from mo10.iij4u.or.jp ([210.138.174.78]:60759 "EHLO mo10.iij4u.or.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756933AbXIIOjv (ORCPT ); Sun, 9 Sep 2007 10:39:51 -0400 In-Reply-To: <46E40319.4030704@panasas.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: bharrosh@panasas.com Cc: tomof@acm.org, linux-scsi@vger.kernel.org, jens.axboe@oracle.com, James.Bottomley@SteelEye.com, fujita.tomonori@lab.ntt.co.jp On Sun, 09 Sep 2007 17:28:41 +0300 Boaz Harrosh wrote: > On Sun, Sep 09 2007 at 16:47 +0300, FUJITA Tomonori wrote: > > On Sun, 09 Sep 2007 13:12:03 +0300 > > Boaz Harrosh wrote: > > > >> On Fri, Sep 07 2007 at 0:50 +0300, FUJITA Tomonori wrote: > >>> Signed-off-by: FUJITA Tomonori > >>> --- > >>> ... > >>> @@ -425,8 +426,8 @@ int srp_cmd_queue(struct Scsi_Host *shost, struct srp_cmd *cmd, void *info, > >>> > >>> sc->SCp.ptr = info; > >>> memcpy(sc->cmnd, cmd->cdb, MAX_COMMAND_SIZE); > >>> - sc->request_bufflen = len; > >>> - sc->request_buffer = (void *) (unsigned long) addr; > >>> + sc->sdb.length = len; > >>> + sc->sdb.sglist = (void *) (unsigned long) addr; > >>> sc->tag = tag; > >>> err = scsi_tgt_queue_command(sc, (struct scsi_lun *) &cmd->lun, cmd->tag); > >>> if (err) > >> What is done here in srp_cmd_queue() looks scary to me. even today. > >> What is that u64 addr that gets truncated to unsigned long and put > >> on sglist? What data-buffer "len" is suppose to describe? And "dir" > >> is for what data? > > > > No trancated since it's used for an address. addr, data length, and > > data transfer direction though they are not used now. > > > I wish you could maybe clean up the unused stuff, Well, I put them for Xen scsiback driver though now I could remove it. > and/or give addr its proper type. If it's a pointer than make it a > pointer. You need to read the SRP spec. > Also you are implying a use_sg==0 here which is not allowed. > > > > >> It is made to look like addr is a linear pointer with a use_sg==0 > >> issued command, which is no longer allowed. Only we know it is not, > >> because of the "(void *)(unsigned long) addr;" which is a bug in > >> 64-bit. > >> > >> If this is a totally private message sent threw the scsi-ml. I would > >> rather it was done with DMA_NONE,bufflen=0,sglist=NULL and put all > >> the user-info into scsi_cmnd.SCp like above "void* info". > > > > tgt doesn't queue a command to scsi-ml. It queues it to user space. > > Even though. Please don't misuse scsi_cmnd members in this way. > If you are not using any of scsi-ml functions on these commands and > they do not carry sg-lists than why use a scsi_cmnd at all? We try to use scsi-ml and transport class as much as possible. > You can just use a tgt private structure. And we don't try to do this. > If these commands do go through some scsi-ml functions than banging > scsi_cmnd.sdb.sglist this way is dangerous. As I said, these commands will not go to scsi-ml in a way as you think.