Re: [RFC] aic7xxx - ahc_done check SCB_ACTIVE for tagged transactions

[Hannes Reinecke <hare@suse.de>]

David Milburn wrote:
> Hannes,
> 
> Does ahc_done need to check the SCB_ACTIVE flag only if the SCB
> is not in the untagged queue before panic?
> 
> If the driver is in error recovery, you may end panic'ing
> on a TUR that is in the untagged queue.
> 
> Attempting to queue an ABORT message
> CDB: 0x0 0x0 0x0 0x0 0x0 0x0
> SCB 3 done'd twice
> 
> This patch is included in Adaptec's 6.3.11 driver on their 
> website.
> 
> Thank you,
> David
> 
> --- scsi-misc-2.6.git/drivers/scsi/aic7xxx/aic7xxx_osm.c.abort
> +++ scsi-misc-2.6.git/drivers/scsi/aic7xxx/aic7xxx_osm.c
> @@ -1658,9 +1658,12 @@ ahc_done(struct ahc_softc *ahc, struct s
>  		untagged_q = &(ahc->untagged_queues[target_offset]);
>  		TAILQ_REMOVE(untagged_q, scb, links.tqe);
>  		BUG_ON(!TAILQ_EMPTY(untagged_q));
> -	}
> -
> -	if ((scb->flags & SCB_ACTIVE) == 0) {
> +	} else if ((scb->flags & SCB_ACTIVE) == 0) {
> +		/*
> +		 * Transactions aborted from the untagged queue may
> +		 * not have been dispatched to the controller, so
> +		 * only check the SCB_ACTIVE flag for tagged transactions.
> +		 */
>  		printf("SCB %d done'd twice\n", scb->hscb->tag);
>  		ahc_dump_card_state(ahc);
>  		panic("Stopping for safety");
> 
Yes, this looks correct. The SCB_ACTIVE flag is reset when doing an ahc_scb_free()
at the very end of ahc_done(). And seeing that we are re-using scbs for error recovery
we might indeed end up with an scb with SCB_ACTIVE is set.

But I'll do some more investigation.
Do you have any setup to exercise this?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Markus Rex, HRB 16746 (AG Nürnberg)
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