2 * include/linux/eventpoll.h ( Efficient event polling implementation )
3 * Copyright (C) 2001,...,2006 Davide Libenzi
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.
10 * Davide Libenzi <davidel@xmailserver.org>
14 #ifndef _LINUX_EVENTPOLL_H
15 #define _LINUX_EVENTPOLL_H
18 #include <linux/fcntl.h>
19 #include <linux/types.h>
21 /* Flags for epoll_create1. */
22 #define EPOLL_CLOEXEC O_CLOEXEC
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 #define EPOLL_CTL_DISABLE 4
31 * Request the handling of system wakeup events so as to prevent system suspends
32 * from happening while those events are being processed.
34 * Assuming neither EPOLLET nor EPOLLONESHOT is set, system suspends will not be
35 * re-allowed until epoll_wait is called again after consuming the wakeup
38 * Requires CAP_BLOCK_SUSPEND
40 #define EPOLLWAKEUP (1 << 29)
42 /* Set the One Shot behaviour for the target file descriptor */
43 #define EPOLLONESHOT (1 << 30)
45 /* Set the Edge Triggered behaviour for the target file descriptor */
46 #define EPOLLET (1 << 31)
49 * On x86-64 make the 64bit structure have the same alignment as the
50 * 32bit structure. This makes 32bit emulation easier.
52 * UML/x86_64 needs the same packing as x86_64
55 #define EPOLL_PACKED __attribute__((packed))
67 /* Forward declarations to avoid compiler errors */
73 /* Used to initialize the epoll bits inside the "struct file" */
74 static inline void eventpoll_init_file(struct file
*file
)
76 INIT_LIST_HEAD(&file
->f_ep_links
);
77 INIT_LIST_HEAD(&file
->f_tfile_llink
);
81 /* Used to release the epoll bits inside the "struct file" */
82 void eventpoll_release_file(struct file
*file
);
85 * This is called from inside fs/file_table.c:__fput() to unlink files
86 * from the eventpoll interface. We need to have this facility to cleanup
87 * correctly files that are closed without being removed from the eventpoll
90 static inline void eventpoll_release(struct file
*file
)
94 * Fast check to avoid the get/release of the semaphore. Since
95 * we're doing this outside the semaphore lock, it might return
96 * false negatives, but we don't care. It'll help in 99.99% of cases
97 * to avoid the semaphore lock. False positives simply cannot happen
98 * because the file in on the way to be removed and nobody ( but
99 * eventpoll ) has still a reference to this file.
101 if (likely(list_empty(&file
->f_ep_links
)))
105 * The file is being closed while it is still linked to an epoll
106 * descriptor. We need to handle this by correctly unlinking it
107 * from its containers.
109 eventpoll_release_file(file
);
114 static inline void eventpoll_init_file(struct file
*file
) {}
115 static inline void eventpoll_release(struct file
*file
) {}
119 #endif /* #ifdef __KERNEL__ */
121 #endif /* #ifndef _LINUX_EVENTPOLL_H */
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