Re: [PATCH] SCSI: export sas_hash_addr()

[James Bottomley <James.Bottomley@SteelEye.com>]

On Sun, 2007-09-30 at 13:44 -0400, Jeff Garzik wrote:
> James Bottomley wrote:
> > On Thu, 2007-09-27 at 21:01 -0400, Jeff Garzik wrote:
> >> James Bottomley wrote:
> >>> On Wed, 2007-09-26 at 03:35 -0400, Jeff Garzik wrote:
> >>>> sas_hash_addr() is the spec-defined standard hashing function.  Make it
> >>>> available to drivers that need it.
> >>> I'm not opposed in principle to exporting this, but I have a hard time
> >>> understanding why a driver would need it.
> >>>
> >>> The hashed address is a property of the constructed SAS frames, which is
> >>> done in libsas.  The driver shouldn't really be calculating its own hash
> >>> instead of using what libsas provides ... or is this because the hashed
> >>> self address isn't calculated by the HBA so it needs to be programmed or
> >>> something?
> >> It is needed to build the SSP frame header.
> >>
> >> If there is common code that does that, I will definitely use that, but 
> >> do not see any such code.
> > 
> > The way you're supposed to build the frame header is in
> > lldd_execute_task().  Here, if you need the hashed address of the
> > destination, you copy it out of the domain_device (dev field of struct
> > sas_task).
> 
> That's the destination.  I need it for the source.

The source should come from dev->port->ha->hashed_sas_addr ...
traditionally it's just your sas_ha_struct that you passed into
sas_register_ha.  The register function fills in the hashed address and
you can pick it out again.

James