blob: 84cfa8bbdc3698fc3a1fdb998d8c606e4d6e9ced [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * include/linux/eventpoll.h ( Efficent event polling implementation )
Davide Libenzi3419b232006-06-25 05:48:14 -07003 * Copyright (C) 2001,...,2006 Davide Libenzi
Linus Torvalds1da177e2005-04-16 15:20:36 -07004 *
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" */
Benjamin LaHaise5a6b7952006-03-23 03:01:03 -080055static inline void eventpoll_init_file(struct file *file)
56{
57 INIT_LIST_HEAD(&file->f_ep_links);
58 spin_lock_init(&file->f_ep_lock);
59}
60
Linus Torvalds1da177e2005-04-16 15:20:36 -070061
62/* Used to release the epoll bits inside the "struct file" */
63void eventpoll_release_file(struct file *file);
64
65/*
66 * This is called from inside fs/file_table.c:__fput() to unlink files
67 * from the eventpoll interface. We need to have this facility to cleanup
68 * correctly files that are closed without being removed from the eventpoll
69 * interface.
70 */
71static inline void eventpoll_release(struct file *file)
72{
73
74 /*
75 * Fast check to avoid the get/release of the semaphore. Since
76 * we're doing this outside the semaphore lock, it might return
77 * false negatives, but we don't care. It'll help in 99.99% of cases
78 * to avoid the semaphore lock. False positives simply cannot happen
79 * because the file in on the way to be removed and nobody ( but
80 * eventpoll ) has still a reference to this file.
81 */
82 if (likely(list_empty(&file->f_ep_links)))
83 return;
84
85 /*
86 * The file is being closed while it is still linked to an epoll
87 * descriptor. We need to handle this by correctly unlinking it
88 * from its containers.
89 */
90 eventpoll_release_file(file);
91}
92
Linus Torvalds1da177e2005-04-16 15:20:36 -070093#else
94
95static inline void eventpoll_init_file(struct file *file) {}
96static inline void eventpoll_release(struct file *file) {}
97
98#endif
99
100#endif /* #ifdef __KERNEL__ */
101
102#endif /* #ifndef _LINUX_EVENTPOLL_H */
103