Arve Hjønnevåg <arve@xxxxxxxxxxx> wrote: > On Fri, Mar 22, 2013 at 3:31 AM, Eric Wong <normalperson@xxxxxxxx> wrote: > > Arve Hjønnevåg <arve@xxxxxxxxxxx> wrote: > >> On Thu, Mar 21, 2013 at 8:24 PM, Eric Wong <normalperson@xxxxxxxx> wrote: > >> > > >> > With EPOLLET and improper usage (not hitting EAGAIN), the event now > >> > has a larger window to be lost (as mentioned in my changelog). > >> > > >> > >> What about the case where EPOLLET is not set? The old code did not > >> drop events in that case. > > > > Nothing is dropped, if the event wasn't on the ready list before, > > ep_poll_callback may still append the ready list while __put_user > > is running. > > > > If the event was on the ready list: > > > > 1) It does not matter for EPOLLONESHOT, it'll get masked out and > > discarded in the next ep_send_events call until ep_modify reenables > > it. Since ep_modify and ep_send_events both take ep->mtx, there's > > no conflict. > > > > 2) Level Trigger - event stays ready, so nothing is dropped. > > > > At some point the level triggered event has to get cleared. As far as > I can tell, your new code will drop new events that occur between > "revents = ep_item_poll(epi, &pt);" and "epi->state = EP_STATE_IDLE;" > in that case. Thanks for catching that, I'll need to fix that. Maybe reintroduce EP_STATE_DEQUEUE, but just for the (LT && !revents) case. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
