On Mon, 29 Oct 2012, James Bottomley wrote: > On Mon, 2012-10-29 at 17:01 +0800, Aaron Lu wrote: > > 2 interfaces are added to block/unblock events for the disk sr manages. > > This is used by SATA ZPODD, when ODD is runtime powered off, the events > > poll is no longer needed so better be blocked. And once powered on, > > events poll will be unblocked. > > > > These 2 interfaces are needed here because SATA layer does not have > > access to the gendisk structure sr manages. > > I'm afraid this is a nasty layering violation. You can't have a low > level driver have knowledge of a call back in an upper layer one (in > this case sr_block_events). > > This is all done it looks like because of the problem of getting access > to the scsi_cd structure from libata, but it's not the right way to > solve it. > > I also don't really think you need to do any blocking or unblocking. As > I said in the previous thread, just fake the events the standard tells > you to, so userspace can probe to its heart's content and you can keep > the device powered off. James, one of us has misunderstood the event-polling mechanism. As far as I know, the polling calls that Aaron is concerned with are generated by the kernel, not by userspace. Alan Stern -- 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
