From: Mike Anderson <andmike@us.ibm.com>
To: Jeremy Higdon <jeremy@classic.engr.sgi.com>
Cc: linux-scsi@vger.kernel.org
Subject: Re: request_buffer versus buffer in Scsi_Cmnd
Date: Fri, 27 Sep 2002 09:29:38 -0700 [thread overview]
Message-ID: <20020927162938.GA1366@beaverton.ibm.com> (raw)
In-Reply-To: <200209270915.CAA96467@classic.engr.sgi.com>
Jeremy Higdon [jeremy@classic.engr.sgi.com] wrote:
> I notice that the qlogicfc driver calls pci_map_sg with the request_buffer
> field and pci_unmap_sg with the buffer field.
>
> >From looking at the code in drivers/scsi/scsi*, it would appear that they
> are mostly the same, and the fact that qlogicfc works would seem to confirm
> that. However, the fact that there are two different fields leads me
> to ask what the difference is supposed to be.
>
There are a few fields in the Scsi_Cmnd that are duplicated to contain
the original values that the scsi cmd was submitted with mostly for retry.
Some Pairs:
request_buffer, buffer
request_bufflen, bufflen
use_sg, old_use_sg
etc.
a few more are listed in the scsi_retry_command.
-andmike
--
Michael Anderson
andmike@us.ibm.com
next prev parent reply other threads:[~2002-09-27 16:29 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-27 9:15 request_buffer versus buffer in Scsi_Cmnd Jeremy Higdon
2002-09-27 16:29 ` Mike Anderson [this message]
2002-09-28 1:50 ` Jeremy Higdon
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