RE: [PATCH V5 01/17] scsi: fixing the "type" for well known LUs

Subhash Jadavani
2014-09-25T06:18:25Z

>> > + * some devices may respond with wrong type for
>> > + * well-known logical units. Force well-known type
>> > + * to enumerate them correctly.
>> > + */
>> > + if (scsi_is_wlun(sdev->lun))
>> > + sdev->type = TYPE_WLUN;
>> > }
> ...
>
> My only concern is that the peripheral device type was included at the
outset in spc3r01 in 2001, so a design that can't get this right might have
other problems. A print might be justified to report something is amiss:
>
> if (scsi_is_wlun(sdev->lun) && sdev->type != TYPE_WLUN) {
> sdev_printk(KERN_WARNING, sdev,
> "%s: correcting incorrect peripheral device type
0x%x for W-LUN 0x%16phN\n",
> __func__, sdev->type, sdev->lun);
> sdev->type = TYPE_WLUN;
> }

Agreed, will take care of this in next patch revision.

-----Original Message-----
From: linux-scsi-owner@vger.kernel.org
[mailto:linux-scsi-owner@vger.kernel.org] On Behalf Of Elliott, Robert
(Server Storage)
Sent: Wednesday, September 24, 2014 1:50 PM
To: Christoph Hellwig; Dolev Raviv
Cc: James.Bottomley@HansenPartnership.com; linux-scsi@vger.kernel.org;
linux-scsi-owner@vger.kernel.org; linux-arm-msm@vger.kernel.org;
santoshsy@gmail.com; Subhash Jadavani; Sujit Reddy Thumma; Martin K.
Petersen
Subject: RE: [PATCH V5 01/17] scsi: fixing the "type" for well known LUs

> From: Christoph Hellwig [mailto:hch@infradead.org]
...
> On Wed, Sep 24, 2014 at 06:13:57PM +0300, Dolev Raviv wrote:
> > From: Subhash Jadavani <subhashj@codeaurora.org>
> >
> > Some devices may respond with wrong type for well-known logical units.
> > This patch forces well-known type for devices which doesn't report
> > it correct.
>
> This looks fine to me, as the well known LUN addresses seem to be
> nailed down nicely in t10, but let's see if Martin or Robert disagree..
>
...
> > diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
> > index 56675db..a34db9e 100644
> > --- a/drivers/scsi/scsi_scan.c
> > +++ b/drivers/scsi/scsi_scan.c
> > @@ -805,6 +805,14 @@ static int scsi_add_lun(struct scsi_device
> > *sdev,
> unsigned char *inq_result,
> > } else {
> > sdev->type = (inq_result[0] & 0x1f);
> > sdev->removable = (inq_result[1] & 0x80) >> 7;
> > +
> > + /*
> > + * some devices may respond with wrong type for
> > + * well-known logical units. Force well-known type
> > + * to enumerate them correctly.
> > + */
> > + if (scsi_is_wlun(sdev->lun))
> > + sdev->type = TYPE_WLUN;
> > }
...

My only concern is that the peripheral device type was included at the
outset in spc3r01 in 2001, so a design that can't get this right might have
other problems. A print might be justified to report something is amiss:

if (scsi_is_wlun(sdev->lun) && sdev->type != TYPE_WLUN) {
sdev_printk(KERN_WARNING, sdev,
"%s: correcting incorrect peripheral device type
0x%x for W-LUN 0x%16phN\n",
__func__, sdev->type, sdev->lun);
sdev->type = TYPE_WLUN;
}

---
Rob Elliott HP Server Storage

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