Re: [PATCH] scsi_dh_alua: Do not run STPG for implicit ALUA

[Hannes Reinecke <hare@xxxxxxx>]

On 10/18/19 11:44 PM, Martin K. Petersen wrote:
> Hannes,
>
> > If a target only supports implicit ALUA sending a SET TARGET PORT
> > GROUPS command is not only pointless, but might actually cause issues.
>
> We already have a conditional in alua_stpg():
>
>          if (!(pg->tpgs & TPGS_MODE_EXPLICIT)) {
>                  /* Only implicit ALUA supported, retry */
>                  return SCSI_DH_RETRY;
>          }
>
> > @@ -832,6 +832,10 @@ static void alua_rtpg_work(struct work_struct *work)
> >   		if (err != SCSI_DH_OK)
> >   			pg->flags &= ~ALUA_PG_RUN_STPG;
> >   	}
> > +	/* Do not run STPG if only implicit ALUA is supported */
> > +	if (scsi_device_tpgs(sdev) == TPGS_MODE_IMPLICIT)
> > +		pg->flags &= ~ALUA_PG_RUN_STPG;
> > +
> >   	if (pg->flags & ALUA_PG_RUN_STPG) {
> >   		pg->flags &= ~ALUA_PG_RUN_STPG;
> >   		spin_unlock_irqrestore(&pg->lock, flags);
>
> Instead of checking for EXPLICIT one place and checking for !IMPLICIT
> another, can we consolidate the two and maybe do:
>
>    	if (pg->flags & ALUA_PG_RUN_STPG &&
>              scsi_device_tpgs(sdev) == TPGS_MODE_EXPLICIT) {
>          	[...]
>
> and then remove the redundant check in alua_stpg()?
Good point.
Will be resending the patch.

Cheers,

Hannes
--
Dr. Hannes Reinecke            Teamlead Storage & Networking
hare@xxxxxxx                              +49 911 74053 688
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