[PATCH] epoll with selectable ET/LT behaviour ...

This patch adds selectable EdgeTriggered/LevelTriggered behaviour to
epoll.

It has been widely discussed on lkml about two weeks ago and everyone
very welcome the change.  It has been even more widely discussed through
private emails with application developers, that do not feel confortable
posting on lkml.  The great value of the patch is that selecting the LT
behaviour, applications using poll/select can be ported very easily to
epoll, making existing apps to benefit from epoll scalability with very
short ETA's.

The API remains the same with the addition of a EPOLLET event flag that
sets the LT/ET behaviour for that fd.

include/linux/eventpoll.h

 /*
  *  include/linux/eventpoll.h ( Efficent event polling implementation )
- *  Copyright (C) 2001,...,2002	 Davide Libenzi
+ *  Copyright (C) 2001,...,2003	 Davide Libenzi
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -20,6 +20,9 @@
 #define EPOLL_CTL_DEL 2
 #define EPOLL_CTL_MOD 3
 
+/* Set the Edge Triggered behaviour for the target file descriptor */
+#define EPOLLET (1 << 31)
+
 struct epoll_event {
 	__u32 events;
 	__u64 data;