RE: scsi: fix target reset handling

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

On Tue, 2008-03-04 at 10:40 -0700, Hagan, Steve wrote:
> Windows (StorPort drivers) supports LUN, target, and bus resets in a
> hierarchical fashion.  If an I/O times out, Storport will issue a LUN
> reset first.  If that fails, it will escalate to a target reset.  If
> that fails, it will escalate to a bus reset.
> 
> What does "fail" mean?

Fail means the driver was unable to perform the action.  i.e failure of
a LUN reset means we couldn't get the TMF out.

>   If the TM request returns with a non-success
> status, or if there are outstanding I/O's for the scope of the reset
> remaining after we receive the TM reply, then the reset is considered
> failed.

Outstanding I/O is a dubious point.  Your driver could have outstanding
I/O for the LUN after a LUN reset, but if the device correctly executed
it, it will have cleared its queue.

>   Our miniport driver will return error status back to Storport
> and it will escalate to the next level of reset.  A bus reset cannot be
> failed back to Storport.  If a bus reset fails (as above) then the only
> recourse if for the miniport to do a hard reset of the adapter and
> return all outstanding I/O's with reset status.

That's pretty much what the default error handler does.

James