1/*
2 * include/linux/eventpoll.h ( Efficient 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#ifndef _LINUX_EVENTPOLL_H
14#define _LINUX_EVENTPOLL_H
15
16#include <uapi/linux/eventpoll.h>
17#include <uapi/linux/kcmp.h>
18
19
20/* Forward declarations to avoid compiler errors */
21struct file;
22
23
24#ifdef CONFIG_EPOLL
25
26#ifdef CONFIG_CHECKPOINT_RESTORE
27struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd, unsigned long toff);
28#endif
29
30/* Used to initialize the epoll bits inside the "struct file" */
31static inline void eventpoll_init_file(struct file *file)
32{
33 INIT_LIST_HEAD(&file->f_ep_links);
34 INIT_LIST_HEAD(&file->f_tfile_llink);
35}
36
37
38/* Used to release the epoll bits inside the "struct file" */
39void eventpoll_release_file(struct file *file);
40
41/*
42 * This is called from inside fs/file_table.c:__fput() to unlink files
43 * from the eventpoll interface. We need to have this facility to cleanup
44 * correctly files that are closed without being removed from the eventpoll
45 * interface.
46 */
47static inline void eventpoll_release(struct file *file)
48{
49
50 /*
51 * Fast check to avoid the get/release of the semaphore. Since
52 * we're doing this outside the semaphore lock, it might return
53 * false negatives, but we don't care. It'll help in 99.99% of cases
54 * to avoid the semaphore lock. False positives simply cannot happen
55 * because the file in on the way to be removed and nobody ( but
56 * eventpoll ) has still a reference to this file.
57 */
58 if (likely(list_empty(&file->f_ep_links)))
59 return;
60
61 /*
62 * The file is being closed while it is still linked to an epoll
63 * descriptor. We need to handle this by correctly unlinking it
64 * from its containers.
65 */
66 eventpoll_release_file(file);
67}
68
69#else
70
71static inline void eventpoll_init_file(struct file *file) {}
72static inline void eventpoll_release(struct file *file) {}
73
74#endif
75
76#endif /* #ifndef _LINUX_EVENTPOLL_H */
77