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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 422 | giacomo | 1 | /* |
| 2 | * include/linux/eventpoll.h ( Efficent event polling implementation ) |
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| 3 | * Copyright (C) 2001,...,2003 Davide Libenzi |
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| 4 | * |
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| 5 | * This program is free software; you can redistribute it and/or modify |
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| 6 | * it under the terms of the GNU General Public License as published by |
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| 7 | * the Free Software Foundation; either version 2 of the License, or |
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| 8 | * (at your option) any later version. |
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| 9 | * |
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| 10 | * Davide Libenzi <davidel@xmailserver.org> |
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| 11 | * |
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| 12 | */ |
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| 13 | |||
| 14 | #ifndef _LINUX_EVENTPOLL_H |
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| 15 | #define _LINUX_EVENTPOLL_H |
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| 16 | |||
| 17 | #include <linux/types.h> |
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| 18 | |||
| 19 | |||
| 20 | /* Valid opcodes to issue to sys_epoll_ctl() */ |
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| 21 | #define EPOLL_CTL_ADD 1 |
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| 22 | #define EPOLL_CTL_DEL 2 |
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| 23 | #define EPOLL_CTL_MOD 3 |
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| 24 | |||
| 25 | /* Set the Edge Triggered behaviour for the target file descriptor */ |
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| 26 | #define EPOLLET (1 << 31) |
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| 27 | |||
| 28 | /* |
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| 29 | * On x86-64 make the 64bit structure have the same alignment as the |
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| 30 | * 32bit structure. This makes 32bit emulation easier. |
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| 31 | */ |
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| 32 | #ifdef __x86_64__ |
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| 33 | #define EPOLL_PACKED __attribute__((packed)) |
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| 34 | #else |
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| 35 | #define EPOLL_PACKED |
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| 36 | #endif |
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| 37 | |||
| 38 | struct epoll_event { |
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| 39 | __u32 events; |
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| 40 | __u64 data; |
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| 41 | } EPOLL_PACKED; |
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| 42 | |||
| 43 | #ifdef __KERNEL__ |
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| 44 | |||
| 45 | /* Forward declarations to avoid compiler errors */ |
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| 46 | struct file; |
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| 47 | |||
| 48 | |||
| 49 | /* Kernel space functions implementing the user space "epoll" API */ |
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| 50 | asmlinkage long sys_epoll_create(int size); |
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| 51 | asmlinkage long sys_epoll_ctl(int epfd, int op, int fd, |
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| 52 | struct epoll_event __user *event); |
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| 53 | asmlinkage long sys_epoll_wait(int epfd, struct epoll_event __user *events, |
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| 54 | int maxevents, int timeout); |
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| 55 | |||
| 56 | #ifdef CONFIG_EPOLL |
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| 57 | |||
| 58 | /* Used to initialize the epoll bits inside the "struct file" */ |
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| 59 | void eventpoll_init_file(struct file *file); |
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| 60 | |||
| 61 | /* Used to release the epoll bits inside the "struct file" */ |
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| 62 | void eventpoll_release_file(struct file *file); |
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| 63 | |||
| 64 | /* |
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| 65 | * This is called from inside fs/file_table.c:__fput() to unlink files |
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| 66 | * from the eventpoll interface. We need to have this facility to cleanup |
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| 67 | * correctly files that are closed without being removed from the eventpoll |
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| 68 | * interface. |
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| 69 | */ |
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| 70 | static inline void eventpoll_release(struct file *file) |
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| 71 | { |
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| 72 | |||
| 73 | /* |
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| 74 | * Fast check to avoid the get/release of the semaphore. Since |
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| 75 | * we're doing this outside the semaphore lock, it might return |
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| 76 | * false negatives, but we don't care. It'll help in 99.99% of cases |
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| 77 | * to avoid the semaphore lock. False positives simply cannot happen |
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| 78 | * because the file in on the way to be removed and nobody ( but |
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| 79 | * eventpoll ) has still a reference to this file. |
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| 80 | */ |
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| 81 | if (likely(list_empty(&file->f_ep_links))) |
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| 82 | return; |
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| 83 | |||
| 84 | /* |
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| 85 | * The file is being closed while it is still linked to an epoll |
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| 86 | * descriptor. We need to handle this by correctly unlinking it |
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| 87 | * from its containers. |
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| 88 | */ |
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| 89 | eventpoll_release_file(file); |
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| 90 | } |
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| 91 | |||
| 92 | |||
| 93 | #else |
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| 94 | |||
| 95 | static inline void eventpoll_init_file(struct file *file) {} |
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| 96 | static inline void eventpoll_release(struct file *file) {} |
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| 97 | |||
| 98 | #endif |
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| 99 | |||
| 100 | #endif /* #ifdef __KERNEL__ */ |
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| 101 | |||
| 102 | #endif /* #ifndef _LINUX_EVENTPOLL_H */ |
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| 103 |