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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Lucas De Marchi25985ed2011-03-30 22:57:33 -03002 * include/linux/eventpoll.h ( Efficient 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
Ulrich Dreppera0998b52008-07-23 21:29:27 -070017/* For O_CLOEXEC */
18#include <linux/fcntl.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019#include <linux/types.h>
20
Ulrich Drepper9fe5ad92008-07-23 21:29:43 -070021/* Flags for epoll_create1. */
Ulrich Dreppera0998b52008-07-23 21:29:27 -070022#define EPOLL_CLOEXEC O_CLOEXEC
Linus Torvalds1da177e2005-04-16 15:20:36 -070023
24/* Valid opcodes to issue to sys_epoll_ctl() */
25#define EPOLL_CTL_ADD 1
26#define EPOLL_CTL_DEL 2
27#define EPOLL_CTL_MOD 3
28
29/* Set the One Shot behaviour for the target file descriptor */
30#define EPOLLONESHOT (1 << 30)
31
32/* Set the Edge Triggered behaviour for the target file descriptor */
33#define EPOLLET (1 << 31)
34
35/*
36 * On x86-64 make the 64bit structure have the same alignment as the
37 * 32bit structure. This makes 32bit emulation easier.
Jeff Diked75e26a2007-03-26 21:32:20 -080038 *
Al Viroca5cd872007-10-29 04:31:16 +000039 * UML/x86_64 needs the same packing as x86_64
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 */
41#ifdef __x86_64__
42#define EPOLL_PACKED __attribute__((packed))
43#else
44#define EPOLL_PACKED
45#endif
46
47struct epoll_event {
48 __u32 events;
49 __u64 data;
50} EPOLL_PACKED;
51
52#ifdef __KERNEL__
53
54/* Forward declarations to avoid compiler errors */
55struct file;
56
57
58#ifdef CONFIG_EPOLL
59
60/* Used to initialize the epoll bits inside the "struct file" */
Benjamin LaHaise5a6b79512006-03-23 03:01:03 -080061static inline void eventpoll_init_file(struct file *file)
62{
63 INIT_LIST_HEAD(&file->f_ep_links);
Benjamin LaHaise5a6b79512006-03-23 03:01:03 -080064}
65
Linus Torvalds1da177e2005-04-16 15:20:36 -070066
67/* Used to release the epoll bits inside the "struct file" */
68void eventpoll_release_file(struct file *file);
69
70/*
71 * This is called from inside fs/file_table.c:__fput() to unlink files
72 * from the eventpoll interface. We need to have this facility to cleanup
73 * correctly files that are closed without being removed from the eventpoll
74 * interface.
75 */
76static inline void eventpoll_release(struct file *file)
77{
78
79 /*
80 * Fast check to avoid the get/release of the semaphore. Since
81 * we're doing this outside the semaphore lock, it might return
82 * false negatives, but we don't care. It'll help in 99.99% of cases
83 * to avoid the semaphore lock. False positives simply cannot happen
84 * because the file in on the way to be removed and nobody ( but
85 * eventpoll ) has still a reference to this file.
86 */
87 if (likely(list_empty(&file->f_ep_links)))
88 return;
89
90 /*
91 * The file is being closed while it is still linked to an epoll
92 * descriptor. We need to handle this by correctly unlinking it
93 * from its containers.
94 */
95 eventpoll_release_file(file);
96}
97
Linus Torvalds1da177e2005-04-16 15:20:36 -070098#else
99
100static inline void eventpoll_init_file(struct file *file) {}
101static inline void eventpoll_release(struct file *file) {}
102
103#endif
104
105#endif /* #ifdef __KERNEL__ */
106
107#endif /* #ifndef _LINUX_EVENTPOLL_H */
108