On Fri, 2005-09-09 at 15:40 -0400, Luben Tuikov wrote:
> +/**
> + * sas_do_lu_discovery -- Discover LUs of a SCSI device
> + * @dev: pointer to a domain device of interest
Aside from all the other problems, this one completely duplicates the
mid-layer infrastructure for handling devices with Logical Units.
> + * Discover logical units present in the SCSI device. I'd like this
> + * to be moved to SCSI Core, but SCSI Core has no concept of a "SCSI
> + * device with a SCSI Target port". A SCSI device with a SCSI Target
> + * port is a device which the _transport_ found, but other than that,
> + * the transport has little or _no_ knowledge about the device.
> + * Ideally, a LLDD would register a "SCSI device with a SCSI Target
> + * port" with SCSI Core and then SCSI Core would do LU discovery of
> + * that device.
That would be what scsi_scan_target() actually does.
> + * REPORT LUNS is mandatory. If a device doesn't support it,
> + * it is broken and you should return it. Nevertheless, we
> + * assume (optimistically) that the link hasn't been severed and
> + * that maybe we can get to the device anyhow.
That's a surprisingly optimistic statement from someone who claims to
have worked in SCSI for so long. We have a huge list of heuristics for
devices that violate the standards in one way or another. We already
have a flag for a SCSI3 device that doesn't respond correctly to
REPORT_LUNS ... and we have a few other reports of potentially more
suspect devices.
Now, if you did this properly and used the mid-layer infrastructure you
wouldn't have to worry about any of this.
> +static int sas_do_lu_discovery(struct domain_device *dev)
Please just handle targets ... scanning beyond targets is best handled
in generic code.
James
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