On 03/18/2014 03:28 PM, Christoph Hellwig wrote: > Does anyone still have a device listed in the blacklist with > BLIST_SINGLELUN? > > From reading the source code I'm not sure the code actually works as > expected currently, or did for a long time. > > While scsi_target_queue_ready makes sure to only queue commands to the > right lun as long as starget_sdev_user is set, scsi_single_lun_run > clears starget_sdev_user as soon as the any command completes on a > target marked with the flag, allowing the following situation: > > - cmd 1 lun 0 submitted > - cmd 2 lun 0 submitted > - cmd 1 lun 0 completed > - cmd 9 lun 1 submitted > > and thus having commands for two luns in flight at the same time > if we hit the narrow enough race of entering the scsi_request_fn > for lun 1 before scsi_single_lun_run does so for lun 0.
You know what, I've been looking at that, too. And indeed, it looks like you're right. I do wonder, though, why we don't do away with the starget_sdev_user and just set max_target_blocked to 1 ... Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage [email protected] +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
