On Fri, Jun 21, 2013 at 10:48 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > Come to think of it, this shouldn't be a problem. Drivers _must_ > insure that all their URBs have completed before their disconnect > routine returns; otherwise the completion handler could get called > after the driver has been unloaded from memory. > > Currently we have no way to enforce this in usbcore, although with the > tasklets we could enforce it. But I don't think it is necessary. It One way of enforcing this I thought of is to wait for completions of all unlinking URBs at the end of usb_hcd_flush_endpoint(). But as you said, it may not be necessary. > would be sufficient to log a warning if the tasklet's URB list isn't > empty when exit_giveback_urb_bh() runs. It won't happen unless there's > a buggy driver. > > Besides, even if you try to flush all the URBs on the tasklet's list at > the end of usb_hcd_flush_endpoint(), you'll still miss the URBs which > have been moved to the local_list in usb_giveback_urb_bh(). You'd have > to wait until the tasklet wasn't running, and it would most likely be a > waste of time. Thanks, -- Ming Lei -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
