On Wed, 2013-10-09 at 19:45 +0200, Hans de Goede wrote: > Hi, > > Thanks for the quick review! > > On 10/09/2013 07:00 PM, Oliver Neukum wrote: > > On Wed, 2013-10-09 at 17:01 +0200, Hans de Goede wrote: > > > >> So I have come up with this patch instead, which adds the ability to > >> suspend wakeups of usb_wait_anchor_empty_timeout() waiters to the usb_anchor > >> functionality, and uses this in __usb_hcd_giveback_urb() to delay wake-ups > >> until the completion handler has run. > > > > Hm. This may mean that we lose wakeups. If the driver reanchors (to the > > same anchor) no wakeup will be issued, ever. > > Correct, and there never was a guarantee one would in the old case too, > if the completion handler re-anchored before the waiting task redid the > list_empty check it would resume waiting anyways. That is true. > So re-anchoring and using usb_wait_anchor_empty_timeout() where mutually > exclusive before this patch already. > > One could argue the new behavior where the wakeup will never happen is actually > better, because that way people will not accidentally start depending happening > on the race happening in such a way that the wakeup does happen. If you find it usefuller, that counts. Regards Oliver -- 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
