epoll: clean up ep_modify

	/*

	 * We need to lock this because we could be hit by

	 * eventpoll_release_file() and epoll_ctl(EPOLL_CTL_DEL).

	 * eventpoll_release_file() and epoll_ctl().

	 */

	mutex_lock(&ep->mtx);

{

	int pwake = 0;

	unsigned int revents;

	unsigned long flags;

	/*

	 * Set the new event interest mask before calling f_op->poll(), otherwise

	 * a potential race might occur. In fact if we do this operation inside

	 * the lock, an event might happen between the f_op->poll() call and the

	 * new event set registering.

	 * Set the new event interest mask before calling f_op->poll();

	 * otherwise we might miss an event that happens between the

	 * f_op->poll() call and the new event set registering.

	 */

	epi->event.events = event->events;

	epi->event.data = event->data; /* protected by mtx */

	/*

	 * Get current event bits. We can safely use the file* here because

	 */

	revents = epi->ffd.file->f_op->poll(epi->ffd.file, NULL);

	spin_lock_irqsave(&ep->lock, flags);

	/* Copy the data member from inside the lock */

	epi->event.data = event->data;

	/*

	 * If the item is "hot" and it is not registered inside the ready

	 * list, push it inside.

	 */

	if (revents & event->events) {

		spin_lock_irq(&ep->lock);

		if (!ep_is_linked(&epi->rdllink)) {

			list_add_tail(&epi->rdllink, &ep->rdllist);

			if (waitqueue_active(&ep->poll_wait))

				pwake++;

		}

		spin_unlock_irq(&ep->lock);

	}

	spin_unlock_irqrestore(&ep->lock, flags);

	/* We have to call this outside the lock */

	if (pwake)