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1/*
2 * include/linux/eventpoll.h ( Efficent event polling implementation )
3 * Copyright (C) 2001,...,2006 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 * UML/x86_64 needs the same packing as x86_64 - UML + UML_X86 +
36 * 64_BIT adds up to UML/x86_64.
37 */
38#ifdef __x86_64__
39#define EPOLL_PACKED __attribute__((packed))
40#else
41#if defined(CONFIG_UML) && defined(CONFIG_UML_X86) && defined(CONFIG_64BIT)
42#define EPOLL_PACKED __attribute__((packed))
43#else
44#define EPOLL_PACKED
45#endif
46#endif
47
48struct epoll_event {
49 __u32 events;
50 __u64 data;
51} EPOLL_PACKED;
52
53#ifdef __KERNEL__
54
55/* Forward declarations to avoid compiler errors */
56struct file;
57
58
59#ifdef CONFIG_EPOLL
60
61/* Used to initialize the epoll bits inside the "struct file" */
62static inline void eventpoll_init_file(struct file *file)
63{
64 INIT_LIST_HEAD(&file->f_ep_links);
65 spin_lock_init(&file->f_ep_lock);
66}
67
68
69/* Used to release the epoll bits inside the "struct file" */
70void eventpoll_release_file(struct file *file);
71
72/*
73 * This is called from inside fs/file_table.c:__fput() to unlink files
74 * from the eventpoll interface. We need to have this facility to cleanup
75 * correctly files that are closed without being removed from the eventpoll
76 * interface.
77 */
78static inline void eventpoll_release(struct file *file)
79{
80
81 /*
82 * Fast check to avoid the get/release of the semaphore. Since
83 * we're doing this outside the semaphore lock, it might return
84 * false negatives, but we don't care. It'll help in 99.99% of cases
85 * to avoid the semaphore lock. False positives simply cannot happen
86 * because the file in on the way to be removed and nobody ( but
87 * eventpoll ) has still a reference to this file.
88 */
89 if (likely(list_empty(&file->f_ep_links)))
90 return;
91
92 /*
93 * The file is being closed while it is still linked to an epoll
94 * descriptor. We need to handle this by correctly unlinking it
95 * from its containers.
96 */
97 eventpoll_release_file(file);
98}
99
100#else
101
102static inline void eventpoll_init_file(struct file *file) {}
103static inline void eventpoll_release(struct file *file) {}
104
105#endif
106
107#endif /* #ifdef __KERNEL__ */
108
109#endif /* #ifndef _LINUX_EVENTPOLL_H */
110