1 /* 2 * include/linux/eventpoll.h ( Efficent 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 <[email protected]> 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. 34 * 35 * UML/x86_64 needs the same packing as x86_64 36 */ 37 #ifdef __x86_64__ 38 #define EPOLL_PACKED __attribute__((packed)) 39 #else 40 #define EPOLL_PACKED 41 #endif 42 43 struct epoll_event { 44 __u32 events; 45 __u64 data; 46 } EPOLL_PACKED; 47 48 #ifdef __KERNEL__ 49 50 /* Forward declarations to avoid compiler errors */ 51 struct file; 52 53 54 #ifdef CONFIG_EPOLL 55 56 /* Used to initialize the epoll bits inside the "struct file" */ 57 static inline void eventpoll_init_file(struct file *file) 58 { 59 INIT_LIST_HEAD(&file->f_ep_links); 60 spin_lock_init(&file->f_ep_lock); 61 } 62 63 64 /* Used to release the epoll bits inside the "struct file" */ 65 void eventpoll_release_file(struct file *file); 66 67 /* 68 * This is called from inside fs/file_table.c:__fput() to unlink files 69 * from the eventpoll interface. We need to have this facility to cleanup 70 * correctly files that are closed without being removed from the eventpoll 71 * interface. 72 */ 73 static inline void eventpoll_release(struct file *file) 74 { 75 76 /* 77 * Fast check to avoid the get/release of the semaphore. Since 78 * we're doing this outside the semaphore lock, it might return 79 * false negatives, but we don't care. It'll help in 99.99% of cases 80 * to avoid the semaphore lock. False positives simply cannot happen 81 * because the file in on the way to be removed and nobody ( but 82 * eventpoll ) has still a reference to this file. 83 */ 84 if (likely(list_empty(&file->f_ep_links))) 85 return; 86 87 /* 88 * The file is being closed while it is still linked to an epoll 89 * descriptor. We need to handle this by correctly unlinking it 90 * from its containers. 91 */ 92 eventpoll_release_file(file); 93 } 94 95 #else 96 97 static inline void eventpoll_init_file(struct file *file) {} 98 static inline void eventpoll_release(struct file *file) {} 99 100 #endif 101 102 #endif /* #ifdef __KERNEL__ */ 103 104 #endif /* #ifndef _LINUX_EVENTPOLL_H */ 105 106