Re: [PATCH] scsi: Convert scsi_host->cmd_serial_number to odd numbered atomic_t counter

Mike Anderson
2010-11-11T22:37:01Z

James Bottomley <James.Bottomley@suse.de> wrote:
> On Thu, 2010-11-11 at 13:37 -0800, Nicholas A. Bellinger wrote:
> >
> > ..snip..
> >
> > Sounds good to me, but you will recall the last attempt to make
> > scsi_cmd_get_serial() optional for the special case LLDs, that we
> > started running quickly in the legacy usage of cmd->serial_number in
> > scsi_softirq_done() and the side effects in scsi_try_to_abort_cmd(), who
> > use is complex enough that we have not found a proper resolution
> > sufficent to andmike discussed here:
>
> Yes, that's what I meant by "eliminate the overloading of the serial
> number zero value" above. This needs fixing before the serial number
> can be dumped for fast hba drivers.
>

In the last email referenced below I believed that since
scsi_softirq_done is calling scsi_eh_scmd_add without the
SCSI_EH_CANCEL_CMD flag set this will stop scsi_try_to_abort_cmd from
being called. Since scsi_softirq_done is the one setting serial_number
to 0 I do not believe we can hit the serial number == 0 check in
scsi_try_to_abort_cmd anymore.

> > http://marc.info/?l=linux-scsi&m=128820726325009&w=2

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