Re: eh_abort_handler and calling scsi_done

[Mike Anderson <andmike@linux.vnet.ibm.com>]

Brian King <brking@linux.vnet.ibm.com> wrote:
> Your assessment sounds correct to me. The other caveat to note is that
> if for some reason in your eh_abort_handler you don't think the command
> is still outstanding, you should return SUCCESS for this as well.
> 
> -Brian
> 
> Christof Schmitt wrote:
> > I am investigating what is required from a LLD when SCSI commands time
> > out and the SCSI EH calls the eh_abort_handler. The documentation in
> > scsi_eh.txt states:
> > 
> >     <<scsi_eh_abort_cmds>>
> > 
> > 	This action is taken for each timed out command.
> > 	hostt->eh_abort_handler() is invoked for each scmd.  The
> > 	handler returns SUCCESS if it has succeeded to make LLDD and
> > 	all related hardware forget about the scmd.
> > 
> > From this and from looking at the code, i would conclude:
> > 
> > 1) If the LLD returns FAILED from the eh_abort_handler, then the
> >    command is still allowed to be active in the LLD and the LLD can
> >    call scsi_done any time later (probably latest when the
> >    eh_host_reset_handler flushes everything that is still pending).
> > 
> > 2) While the abort is pending, but before returning SUCCESS from
> >    eh_abort_handler, the LLD can still call scsi_done for the SCSI
> >    command to be aborted (the SCSI command might be returned with a
> >    status "aborted" if the abort succeeds, or "good" if it was
> >    completed just before the abort reached the storage system).
> > 

In cases 1 and 2 above calling scsi_done can be done but will cause the
request to be stopped in blk_complete_request (scsi_done->blk_complete_request) as the timed out handler has already taken ownership of the command.

-andmike
--
Michael Anderson
andmike@linux.vnet.ibm.com