James Bottomley wrote: > On Thu, 2007-07-05 at 14:06 -0700, Kristen Carlson Accardi wrote: >> Since gendisk will now become part of struct scsi_device, we don't need >> to store this value in any private data structs where they already store >> scsi_device. This series cleans up a few drivers which did this. > > Actually, as Al pointed out, we do have lifetime rules issues with doing > this. The problem is that gendisk itself always has a shorter lifetime > than scsi_device (not much shorter, usually, but if you execute a legal > ULD unbind manoeuvre you'll end up with a dangling gendisk pointer). What about having short-lived scsi_device objects? For example: one that lives long enough for a pass-through to send a SCSI command (and receive its response) to one of a target's well known logical units. > The other problem with taking gendisk out of the ULD structure and > putting it into the scsi_device is that for the sg driver, we have two > of them (one for the attached ULD and one for the sg driver). Add the bsg driver and that would make three of them. Or; if the lu's peripheral device type was not of interest to sd, st, sr, and osst; back to two gendisk objects (i.e. one each for sg and bsg). > The fundamental issue seems to be that the gendisk is the holder of all > the other info (queue, ULD etc) not vice versa ... and this patch is > trying to reverse that relationship. A minor issue is the name gendisk ... unless, of course, you go and look at its definition in linux/genhd.h in which case the name looks somewhat appropriate. It looks like a mess [queue, ULD name, major/minor(s), partitions, capacity, disk_stats, kobjects, etc]. That is a considerable amount of superfluous information for "just a tag for requests coming into (a) given queue" when that queue leads to a non-block device. Doug Gilbert - 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
