Re: eh_abort_handler and calling scsi_done

Mike Anderson
2009-03-24T17:46:12Z

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