On Tue, 21 Jul 2009, Sarah Sharp wrote: > There is a FIXME note in usb_kick_khubd() that it may have problems if the hub > isn't bound to the hub driver yet. Since the xHCI hardware can send a port > status change event as soon as the interrupts are turned on, there is a race > condition between registering khubd and the xHCI host controller driver. It should be obvious that this same reasoning applies to other host controller drivers too, not just xHCI. How do they solve it? Answer: They don't. The race condition is already resolved for you by usbcore, in the very first line of usb_hcd_poll_rh_status. Besides, why do you think that usb_kick_khubd() is relevant here? It doesn't get used anywhere on the pathway changed by the patch. > Solve this by ignoring port status change events until after khubd polls the > port status bits for the first time. khubd should notice any changes from > previous events at that time. This change isn't needed. Alan Stern -- 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
