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1da177e4 LT |
1 | /* |
2 | * include/linux/eventpoll.h ( Efficent event polling implementation ) | |
3419b23a | 3 | * Copyright (C) 2001,...,2006 Davide Libenzi |
1da177e4 LT |
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. | |
d75e26a8 JD |
34 | * |
35 | * UML/x86_64 needs the same packing as x86_64 - UML + UML_X86 + | |
36 | * 64_BIT adds up to UML/x86_64. | |
1da177e4 LT |
37 | */ |
38 | #ifdef __x86_64__ | |
39 | #define EPOLL_PACKED __attribute__((packed)) | |
40 | #else | |
d75e26a8 JD |
41 | #if defined(CONFIG_UML) && defined(CONFIG_UML_X86) && defined(CONFIG_64BIT) |
42 | #define EPOLL_PACKED __attribute__((packed)) | |
43 | #else | |
1da177e4 LT |
44 | #define EPOLL_PACKED |
45 | #endif | |
d75e26a8 | 46 | #endif |
1da177e4 LT |
47 | |
48 | struct epoll_event { | |
49 | __u32 events; | |
50 | __u64 data; | |
51 | } EPOLL_PACKED; | |
52 | ||
53 | #ifdef __KERNEL__ | |
54 | ||
55 | /* Forward declarations to avoid compiler errors */ | |
56 | struct file; | |
57 | ||
58 | ||
59 | #ifdef CONFIG_EPOLL | |
60 | ||
61 | /* Used to initialize the epoll bits inside the "struct file" */ | |
5a6b7951 BL |
62 | static 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 | ||
1da177e4 LT |
68 | |
69 | /* Used to release the epoll bits inside the "struct file" */ | |
70 | void 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 | */ | |
78 | static 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 | ||
1da177e4 LT |
100 | #else |
101 | ||
102 | static inline void eventpoll_init_file(struct file *file) {} | |
103 | static inline void eventpoll_release(struct file *file) {} | |
104 | ||
105 | #endif | |
106 | ||
107 | #endif /* #ifdef __KERNEL__ */ | |
108 | ||
109 | #endif /* #ifndef _LINUX_EVENTPOLL_H */ | |
110 |