When talking about "soft" unbinding, the main question seems to be: How soft? It would be easy, for instance, to change usb-storage so that unbinding would wait until the current command was finished. But clearly one wants to do more: Give the upper-level SCSI drivers a chance to shutdown cleanly and issue their FLUSH CACHE commands, wait for all pending commands to complete, and so on. It's the "wait for pending commands to complete" part that is hard. Some commands have relatively long timeouts. Error handler operations have no timeouts. Commands submitted through sg can have effectively infinite timeouts. So how long should we wait? Should there be a scsi_soft_remove_host() routine that accepts a timeout value? It would remove the devices under the host and wait until the timeout expires (if necessary) before aborting all pending commands. Unlike scsi_remove_host(), it would really abort these commands as though they had timed out, instead of simply cancelling them. It would guarantee that when it returned, no commands were still running on the host and no more commands would be submitted. This would essentially be a standardized version of the special code Stefan has put into the sbp2 and firewire-sbp2 drivers. 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
