On Thu, 2013-01-24 at 07:01 -0700, Mike Christie wrote: > On 01/24/2013 04:38 AM, Hannes Reinecke wrote: > > On 01/24/2013 01:19 AM, Bart Van Assche wrote: > >> On Fri, Jan 18, 2013 at 9:27 AM, Ewan D. Milne <emilne@xxxxxxxxxx> wrote: > >>> This patch set adds changes to the SCSI mid-layer, sysfs and scsi_debug > >>> to provide enhanced support for Unit Attention conditions, as well as > >>> detection of reported sense data overflow conditions and some changes > >>> to sense data processing. It also adds a uevent when the reported > >>> capacity changes on an sd device. > >>> > >>> There was some discussion about this a couple of years ago on the > >>> linux-scsi > >>> mailing list: http://marc.info/?l=linux-scsi&m=129702506514742&w=2 > >>> Although one approach is to send all SCSI sense data to a userspace > >>> daemon > >>> for processing, this patch set does not take that approach due to the > >>> difficulty in reliably delivering all of the data. An interesting UA > >>> condition might not be delivered due to a flood of media errors, for > >>> example. > >>> > >>> The mechanism used is to flag when certain UA ASC/ASCQ codes are > >>> received > >>> that report asynchronous changes to the storage device configuration. > >>> An appropriate uevent is then generated for the scsi_device or > >>> scsi_target > >>> object. An aggregation mechanism is used to avoid generating uevents at > >>> too high a rate, and to coalesce multiple UAs reported by LUNs on the > >>> same target for a REPORTED LUNS DATA HAS CHANGED sense code. > >> > >> Does this patch series add a function that allows SCSI LLDs to report > >> AEN data to the SCSI core ? What if a SCSI target reports a LUN > >> inventory change via AER to e.g. the iSCSI initiator and that > >> initiator ignores the AEN data ? Will that result in AEN data being > >> ignored and no automatic LUN rescanning ? > >> > > Well, first and foremost we _don't_ have automatic LUN rescanning. > > This patchset just puts in the infrastructure that userspace can know > > _when_ a LUN rescan might be in order. > > > > As for AEN, does iSCSI _do_ AEN? I thought it got removed ... > > The AEN is sent to userspace right now. > > > > > If it does, though, it should schedule an event on its own whenever an > > AER is received. The same goes for LLDDs with vendor-specific AENs; > > thinking of megaraid_sas here ... > > > > Yeah. It would be nicer if there was a wrapper around this code: > > +#ifdef CONFIG_SCSI_ENHANCED_UA > + struct scsi_target *starget = scsi_target(sdev); > + if (atomic_xchg(&starget->lun_change_reported, 1) == 0) > + schedule_delayed_work(&starget->ua_dwork, 2*HZ); > + scmd_printk(KERN_WARNING, scmd, > + "Reported LUNs data has changed"); > +#else > > so drivers do not have to have to duplicate and know that low level of > details. I could move that to an exported function. I guess the questions would be (a) is this the only ASC/ASCQ combination that should be available in that way, and (b) should it be conditional on the config option? Thanks for your comments. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
