Re: [PATCH] scsi : set target can_queue from devinfo flags

[Hannes Reinecke <hare@suse.de>]

Hi James,

James Smart wrote:
> This patch, discussed in the initial thread on target can_queue limits
> (see  http://marc.info/?l=linux-scsi&m=120944296225094&w=2 )
> allows the target can_queue limit to be obtained from the device list based on
> Inquiry data obtained during scan.
> 
> I have pinged several of the array vendors to supply target-port level values
> for their arrays. Hopefully, we will see them populate the device list with some
> real values shortly.
> 
I know :-)

> This patch was cut against scsi-misc-2.6, and depends on Mike Christies patches
> contained in the original thread.
> 
Hmph.

I don't quite agree with this one.
For once, /proc/scsi/scsi has been marked as 'obsolete' for quite some time now,
so adding other usages to this is of questionable value.

And we've actually have a similar issue when developing the SCSI device_handler
stuff where we also have a device list to maintain.

Seeing there is quite some overlap between those two cases I think we should
come up with a way of handling these things properly, ie tied into sysfs.

So, what we should do here is
a) add a 'can_queue' sysfs attribute to the starget (which we can nowadays, as
   the starget is a proper sysfs object)
b) define a 'modalias' style definition for matching SCSI vendor/model/rev
   and create a scsi_devinfo module from which all these special cases
   can be invoked from.

That would also allow us to get rid of the device tables in the device_handler
modules which I never really liked.

What do you think?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Markus Rex, HRB 16746 (AG Nürnberg)
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