From: Matthew Dharm <mdharm-scsi@one-eyed-alien.net>
To: James Bottomley <James.Bottomley@SteelEye.com>
Cc: Douglas Gilbert <dougg@torque.net>,
SCSI Mailing List <linux-scsi@vger.kernel.org>,
bunk@fs.tum.de
Subject: Re: Is scsi_cmnd::underflow still useful?
Date: Mon, 12 Jul 2004 22:09:20 -0700 [thread overview]
Message-ID: <20040713050920.GA31062@one-eyed-alien.net> (raw)
In-Reply-To: <1089680114.2074.198.camel@mulgrave>
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On Mon, Jul 12, 2004 at 07:55:13PM -0500, James Bottomley wrote:
> On Mon, 2004-07-12 at 14:40, Douglas Gilbert wrote:
> > Doesn't look like many LLDs act on scsi_cmnd::underflow.
> > Seems to me that scsi_cmnd::resid is a more general
> > replacement.
>
> well, I know I suggested a recent use of it to the USB people , so I
> don't think it's entirely unused. resid can't be a replacement because
> they mean different things:
>
> resid - number of bytes left over after a transaction
> underflow - driver must return error if less than this amount
> transferred.
I think the recent USB usage of it was because some mid-level drivers look
for the error condition related to the underflow value.
We don't really use it, other than to trigger an error.
Matt
--
Matthew Dharm Home: mdharm-usb@one-eyed-alien.net
Maintainer, Linux USB Mass Storage Driver
Stef, you just got beaten by a ball of DIRT.
-- Greg
User Friendly, 12/7/1997
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next prev parent reply other threads:[~2004-07-13 5:10 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-07-12 19:40 Is scsi_cmnd::underflow still useful? Douglas Gilbert
2004-07-13 0:55 ` James Bottomley
2004-07-13 5:09 ` Matthew Dharm [this message]
2004-07-13 22:09 ` Douglas Gilbert
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