fs/epoll: simplify ep_send_events_proc() ready-list loop

{

	struct ep_send_events_data *esed = priv;

	__poll_t revents;

	struct epitem *epi;

	struct epoll_event __user *uevent;

	struct epitem *epi, *tmp;

	struct epoll_event __user *uevent = esed->events;

	struct wakeup_source *ws;

	poll_table pt;

	init_poll_funcptr(&pt, NULL);

	esed->res = 0;

	/*

	 * We can loop without lock because we are passed a task private list.

	 * Items cannot vanish during the loop because ep_scan_ready_list() is

	 * holding "mtx" during this call.

	 */

	for (esed->res = 0, uevent = esed->events;

	     !list_empty(head) && esed->res < esed->maxevents;) {

		epi = list_first_entry(head, struct epitem, rdllink);

	list_for_each_entry_safe(epi, tmp, head, rdllink) {

		if (esed->res >= esed->maxevents)

			break;

		/*

		 * Activate ep->ws before deactivating epi->ws to prevent

		list_del_init(&epi->rdllink);

		revents = ep_item_poll(epi, &pt, 1);

		/*

		 * If the event mask intersect the caller-requested one,

		 * deliver the event to userspace. Again, ep_scan_ready_list()

		 * is holding "mtx", so no operations coming from userspace

		 * is holding ep->mtx, so no operations coming from userspace

		 * can change the item.

		 */

		if (revents) {

		revents = ep_item_poll(epi, &pt, 1);

		if (!revents)

			continue;

		if (__put_user(revents, &uevent->events) ||

		    __put_user(epi->event.data, &uevent->data)) {

			list_add(&epi->rdllink, head);

			ep_pm_stay_awake(epi);

		}

	}

	}

	return 0;

}