Hello, On Mon, Sep 08, 2014 at 01:42:44PM -0400, Alan Stern wrote: > > This looks like a nasty hack. In theory the QUEUE_FLAG_INIT_DONE should > > be unset on blk_unregister_queue() to match the teardown; it's only > > accident it isn't. del_gendisk() in sd_remove() is supposed to tear a > > lot of queue stuff down. > > It's not clear what the operative assumptions are. The comment in > blk_register_queue() implies that bypass is active only because it was > set up that way when the queue was created. The fact that > blk_unregister_queue() doesn't call blk_queue_bypass_start() seems to > support this view -- although it could also be a simple oversight. > > Hopefully Tejun can clear this iup. Maintaining the initial bypass till queue registration is an optimization because shutting down a fully functional queue is a costly operation and there are drivers which set and destroy queues repeatedly while probing, so, yeah, it's really a special case for when the queue is being registered for the first time. > > Your hack seems to indicate that this doesn't work on the add->del->add > > transtion of a gendisk. > > Indeed, it does not work. As such, the change you suggested makes perfect sense to me. Why wouldn't it work? Thanks. -- tejun -- 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
