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 /* Set the One Shot behaviour for the target file descriptor */ 30 #define EPOLLONESHOT (1 << 30) 31 32 /* Set the Edge Triggered behaviour for the target file descriptor */ 33 #define EPOLLET (1 << 31) 34 35 /* 36 * On x86-64 make the 64bit structure have the same alignment as the 37 * 32bit structure. This makes 32bit emulation easier. 38 * 39 * UML/x86_64 needs the same packing as x86_64 40 */ 41 #ifdef __x86_64__ 42 #define EPOLL_PACKED __attribute__((packed)) 43 #else 44 #define EPOLL_PACKED 45 #endif 46 47 struct epoll_event { 48 __u32 events; 49 __u64 data; 50 } EPOLL_PACKED; 51 52 #ifdef __KERNEL__ 53 54 /* Forward declarations to avoid compiler errors */ 55 struct file; 56 57 58 #ifdef CONFIG_EPOLL 59 60 /* Used to initialize the epoll bits inside the "struct file" */ eventpoll_init_file(struct file * file)61static inline void eventpoll_init_file(struct file *file) 62 { 63 INIT_LIST_HEAD(&file->f_ep_links); 64 INIT_LIST_HEAD(&file->f_tfile_llink); 65 } 66 67 68 /* Used to release the epoll bits inside the "struct file" */ 69 void eventpoll_release_file(struct file *file); 70 71 /* 72 * This is called from inside fs/file_table.c:__fput() to unlink files 73 * from the eventpoll interface. We need to have this facility to cleanup 74 * correctly files that are closed without being removed from the eventpoll 75 * interface. 76 */ eventpoll_release(struct file * file)77static inline void eventpoll_release(struct file *file) 78 { 79 80 /* 81 * Fast check to avoid the get/release of the semaphore. Since 82 * we're doing this outside the semaphore lock, it might return 83 * false negatives, but we don't care. It'll help in 99.99% of cases 84 * to avoid the semaphore lock. False positives simply cannot happen 85 * because the file in on the way to be removed and nobody ( but 86 * eventpoll ) has still a reference to this file. 87 */ 88 if (likely(list_empty(&file->f_ep_links))) 89 return; 90 91 /* 92 * The file is being closed while it is still linked to an epoll 93 * descriptor. We need to handle this by correctly unlinking it 94 * from its containers. 95 */ 96 eventpoll_release_file(file); 97 } 98 99 #else 100 eventpoll_init_file(struct file * file)101static inline void eventpoll_init_file(struct file *file) {} eventpoll_release(struct file * file)102static inline void eventpoll_release(struct file *file) {} 103 104 #endif 105 106 #endif /* #ifdef __KERNEL__ */ 107 108 #endif /* #ifndef _LINUX_EVENTPOLL_H */ 109 110