[RFC PATCH 2/3] epoll: add struct epoll & ioctl() commands

[Nathaniel Yazdani <n1ght.4nd.d4y@gmail.com>]

Add a new 'struct epoll' to the userspace eventpoll interface. Buffers
supplied to read() & write() calls on eventpolls are interpreted as
arrays of this structure. The new structure's only functional difference
from epoll_event is it also holds the associated file descriptor (needed
for write() to properly create events but useful information in general).
Also define the ioctl() command macros to set & get the timeout of an
eventpoll.

Signed-off-by: Nathaniel Yazdani <n1ght.4nd.d4y@gmail.com>
---
diff --git a/include/uapi/linux/eventpoll.h b/include/uapi/linux/eventpoll.h
index bc81fb2..73f817c 100644
--- a/include/uapi/linux/eventpoll.h
+++ b/include/uapi/linux/eventpoll.h
@@ -56,11 +56,21 @@
 #define EPOLL_PACKED
 #endif
 
+/* ioctl() requests */
+#define EPIOC_GETTIMEOUT	_IOR('$', 0x10, int)
+#define EPIOC_SETTIMEOUT	_IOW('$', 0x11, int)
+
 struct epoll_event {
 	__u32 events;
 	__u64 data;
 } EPOLL_PACKED;
 
+struct epoll {
+	int ep_fildes; /* file descriptor */
+	int ep_events; /* triggering events */
+	long long ep_ident; /* entry ID (cf. epoll_event->data) */
+} EPOLL_PACKED; /* A.K.A. "epe" for "eventpoll entry" */
+
 #ifdef CONFIG_PM_SLEEP
 static inline void ep_take_care_of_epollwakeup(struct epoll_event *epev)
 {