Re: linux-2.4.18-modified-scsi-h.patch

From: Andre Hedrick (andre@pyxtechnologies.com)
Date: Tue Nov 19 2002 - 07:16:35 EST


On Tue, 19 Nov 2002, Douglas Gilbert wrote:

> Andre Hedrick wrote:
> > Greetings Doug et al.
> >
> > Please consider the addition of this simple void ptr to the scsi_request
> > struct. The addition of this simple void pointer allows one to map any
> > and all request execution caller the facility to search for a specific
> > operation without having to run in circles. Hunting for these details
> > over the global device list of all HBA's is silly and one of the key
> > reasons why there error recovery path is so painful.
> >
> >
> > Scsi_Request *req = sc_cmd->sc_request;
> > blah_blah_t *trace = NULL;
> >
> > trace = (blah_blah_t *)req->trace_ptr;
> >
> >
> > Therefore the specific transport invoking operations via the midlayer will
> > have the ablity to track and trace any operation.
>
> Andre,
> No need to convince me: I have already put a similar pointer
> in that structure in lk 2.5 (for either sd, st, sr or sg to use).
> In sg case's it saved some ugly looping in (what was formerly
> called) the bottom half handler. Sounds like your motivation is
> similar.
>
> Doug Gilbert

Hey there!

Well it needs to be in all kernels regardless, and if it is in the
scsi_request it is transparent to any given personality device and the
caller may reserve the option to include other key information. Simple
stats of what the queue depth of a given device is and a means to flush
out the commands to force a failure in the case of calling a device reset.

Without being to obvious or rude about the driver model being top down and
not the converse, hunting for given set of operation(s) will almost insure
a driver/device deadlock when racing against the done function.

I am pleased you and I are thinking in the same direction again!

Cheers,

Andre Hedrick, CTO & Founder
iSCSI Software Solutions Provider
http://www.PyXTechnologies.com/

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