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1/*
2 * include/linux/eventpoll.h ( Efficent event polling implementation )
3 * Copyright (C) 2001,...,2003 Davide Libenzi
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * Davide Libenzi <davidel@xmailserver.org>
11 *
12 */
13
14#ifndef _LINUX_EVENTPOLL_H
15#define _LINUX_EVENTPOLL_H
16
17#include <linux/types.h>
18
19
20/* Valid opcodes to issue to sys_epoll_ctl() */
21#define EPOLL_CTL_ADD 1
22#define EPOLL_CTL_DEL 2
23#define EPOLL_CTL_MOD 3
24
25/* Set the One Shot behaviour for the target file descriptor */
26#define EPOLLONESHOT (1 << 30)
27
28/* Set the Edge Triggered behaviour for the target file descriptor */
29#define EPOLLET (1 << 31)
30
31/*
32 * On x86-64 make the 64bit structure have the same alignment as the
33 * 32bit structure. This makes 32bit emulation easier.
34 */
35#ifdef __x86_64__
36#define EPOLL_PACKED __attribute__((packed))
37#else
38#define EPOLL_PACKED
39#endif
40
41struct epoll_event {
42 __u32 events;
43 __u64 data;
44} EPOLL_PACKED;
45
46#ifdef __KERNEL__
47
48/* Forward declarations to avoid compiler errors */
49struct file;
50
51
52#ifdef CONFIG_EPOLL
53
54/* Used to initialize the epoll bits inside the "struct file" */
55void eventpoll_init_file(struct file *file);
56
57/* Used to release the epoll bits inside the "struct file" */
58void eventpoll_release_file(struct file *file);
59
60/*
61 * This is called from inside fs/file_table.c:__fput() to unlink files
62 * from the eventpoll interface. We need to have this facility to cleanup
63 * correctly files that are closed without being removed from the eventpoll
64 * interface.
65 */
66static inline void eventpoll_release(struct file *file)
67{
68
69 /*
70 * Fast check to avoid the get/release of the semaphore. Since
71 * we're doing this outside the semaphore lock, it might return
72 * false negatives, but we don't care. It'll help in 99.99% of cases
73 * to avoid the semaphore lock. False positives simply cannot happen
74 * because the file in on the way to be removed and nobody ( but
75 * eventpoll ) has still a reference to this file.
76 */
77 if (likely(list_empty(&file->f_ep_links)))
78 return;
79
80 /*
81 * The file is being closed while it is still linked to an epoll
82 * descriptor. We need to handle this by correctly unlinking it
83 * from its containers.
84 */
85 eventpoll_release_file(file);
86}
87
88
89#else
90
91static inline void eventpoll_init_file(struct file *file) {}
92static inline void eventpoll_release(struct file *file) {}
93
94#endif
95
96#endif /* #ifdef __KERNEL__ */
97
98#endif /* #ifndef _LINUX_EVENTPOLL_H */
99