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 14 #ifndef _LINUX_EVENTPOLL_H 15 #define _LINUX_EVENTPOLL_H 16 17 /* For O_CLOEXEC */ 18 #include <linux/fcntl.h> 19 #include <linux/types.h> 20 21 /* Flags for epoll_create1. */ 22 #define EPOLL_CLOEXEC O_CLOEXEC 23 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 29 /* 30 * Request the handling of system wakeup events so as to prevent system suspends 31 * from happening while those events are being processed. 32 * 33 * Assuming neither EPOLLET nor EPOLLONESHOT is set, system suspends will not be 34 * re-allowed until epoll_wait is called again after consuming the wakeup 35 * event(s). 36 * 37 * Requires CAP_EPOLLWAKEUP 38 */ 39 #define EPOLLWAKEUP (1 << 29) 40 41 /* Set the One Shot behaviour for the target file descriptor */ 42 #define EPOLLONESHOT (1 << 30) 43 44 /* Set the Edge Triggered behaviour for the target file descriptor */ 45 #define EPOLLET (1 << 31) 46 47 /* 48 * On x86-64 make the 64bit structure have the same alignment as the 49 * 32bit structure. This makes 32bit emulation easier. 50 * 51 * UML/x86_64 needs the same packing as x86_64 52 */ 53 #ifdef __x86_64__ 54 #define EPOLL_PACKED __attribute__((packed)) 55 #else 56 #define EPOLL_PACKED 57 #endif 58 59 struct epoll_event { 60 __u32 events; 61 __u64 data; 62 } EPOLL_PACKED; 63 64 #ifdef __KERNEL__ 65 66 /* Forward declarations to avoid compiler errors */ 67 struct file; 68 69 70 #ifdef CONFIG_EPOLL 71 72 /* Used to initialize the epoll bits inside the "struct file" */ eventpoll_init_file(struct file * file)73static inline void eventpoll_init_file(struct file *file) 74 { 75 INIT_LIST_HEAD(&file->f_ep_links); 76 INIT_LIST_HEAD(&file->f_tfile_llink); 77 } 78 79 80 /* Used to release the epoll bits inside the "struct file" */ 81 void eventpoll_release_file(struct file *file); 82 83 /* 84 * This is called from inside fs/file_table.c:__fput() to unlink files 85 * from the eventpoll interface. We need to have this facility to cleanup 86 * correctly files that are closed without being removed from the eventpoll 87 * interface. 88 */ eventpoll_release(struct file * file)89static inline void eventpoll_release(struct file *file) 90 { 91 92 /* 93 * Fast check to avoid the get/release of the semaphore. Since 94 * we're doing this outside the semaphore lock, it might return 95 * false negatives, but we don't care. It'll help in 99.99% of cases 96 * to avoid the semaphore lock. False positives simply cannot happen 97 * because the file in on the way to be removed and nobody ( but 98 * eventpoll ) has still a reference to this file. 99 */ 100 if (likely(list_empty(&file->f_ep_links))) 101 return; 102 103 /* 104 * The file is being closed while it is still linked to an epoll 105 * descriptor. We need to handle this by correctly unlinking it 106 * from its containers. 107 */ 108 eventpoll_release_file(file); 109 } 110 111 #else 112 eventpoll_init_file(struct file * file)113static inline void eventpoll_init_file(struct file *file) {} eventpoll_release(struct file * file)114static inline void eventpoll_release(struct file *file) {} 115 116 #endif 117 118 #endif /* #ifdef __KERNEL__ */ 119 120 #endif /* #ifndef _LINUX_EVENTPOLL_H */ 121 122