1 /* 2 * include/linux/eventpoll.h ( Efficent event polling implementation ) 3 * Copyright (C) 2001,...,2003 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 #ifdef __x86_64__ 36 #define EPOLL_PACKED __attribute__((packed)) 37 #else 38 #define EPOLL_PACKED 39 #endif 40 41 struct epoll_event { 42 __u32 events; 43 __u64 data; 44 } EPOLL_PACKED; 45 46 #ifdef __KERNEL__ 47 48 /* Forward declarations to avoid compiler errors */ 49 struct file; 50 51 52 #ifdef CONFIG_EPOLL 53 54 /* Used to initialize the epoll bits inside the "struct file" */ 55 void eventpoll_init_file(struct file *file); 56 57 /* Used to release the epoll bits inside the "struct file" */ 58 void eventpoll_release_file(struct file *file); 59 60 /* 61 * This is called from inside fs/file_table.c:__fput() to unlink files 62 * from the eventpoll interface. We need to have this facility to cleanup 63 * correctly files that are closed without being removed from the eventpoll 64 * interface. 65 */ 66 static inline void eventpoll_release(struct file *file) 67 { 68 69 /* 70 * Fast check to avoid the get/release of the semaphore. Since 71 * we're doing this outside the semaphore lock, it might return 72 * false negatives, but we don't care. It'll help in 99.99% of cases 73 * to avoid the semaphore lock. False positives simply cannot happen 74 * because the file in on the way to be removed and nobody ( but 75 * eventpoll ) has still a reference to this file. 76 */ 77 if (likely(list_empty(&file->f_ep_links))) 78 return; 79 80 /* 81 * The file is being closed while it is still linked to an epoll 82 * descriptor. We need to handle this by correctly unlinking it 83 * from its containers. 84 */ 85 eventpoll_release_file(file); 86 } 87 88 89 #else 90 91 static inline void eventpoll_init_file(struct file *file) {} 92 static inline void eventpoll_release(struct file *file) {} 93 94 #endif 95 96 #endif /* #ifdef __KERNEL__ */ 97 98 #endif /* #ifndef _LINUX_EVENTPOLL_H */ 99 100