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 - UML + UML_X86 + 36 * 64_BIT adds up to UML/x86_64. 37 */ 38 #ifdef __x86_64__ 39 #define EPOLL_PACKED __attribute__((packed)) 40 #else 41 #if defined(CONFIG_UML) && defined(CONFIG_UML_X86) && defined(CONFIG_64BIT) 42 #define EPOLL_PACKED __attribute__((packed)) 43 #else 44 #define EPOLL_PACKED 45 #endif 46 #endif 47 48 struct epoll_event { 49 __u32 events; 50 __u64 data; 51 } EPOLL_PACKED; 52 53 #ifdef __KERNEL__ 54 55 /* Forward declarations to avoid compiler errors */ 56 struct file; 57 58 59 #ifdef CONFIG_EPOLL 60 61 /* Used to initialize the epoll bits inside the "struct file" */ 62 static inline void eventpoll_init_file(struct file *file) 63 { 64 INIT_LIST_HEAD(&file->f_ep_links); 65 spin_lock_init(&file->f_ep_lock); 66 } 67 68 69 /* Used to release the epoll bits inside the "struct file" */ 70 void eventpoll_release_file(struct file *file); 71 72 /* 73 * This is called from inside fs/file_table.c:__fput() to unlink files 74 * from the eventpoll interface. We need to have this facility to cleanup 75 * correctly files that are closed without being removed from the eventpoll 76 * interface. 77 */ 78 static inline void eventpoll_release(struct file *file) 79 { 80 81 /* 82 * Fast check to avoid the get/release of the semaphore. Since 83 * we're doing this outside the semaphore lock, it might return 84 * false negatives, but we don't care. It'll help in 99.99% of cases 85 * to avoid the semaphore lock. False positives simply cannot happen 86 * because the file in on the way to be removed and nobody ( but 87 * eventpoll ) has still a reference to this file. 88 */ 89 if (likely(list_empty(&file->f_ep_links))) 90 return; 91 92 /* 93 * The file is being closed while it is still linked to an epoll 94 * descriptor. We need to handle this by correctly unlinking it 95 * from its containers. 96 */ 97 eventpoll_release_file(file); 98 } 99 100 #else 101 102 static inline void eventpoll_init_file(struct file *file) {} 103 static inline void eventpoll_release(struct file *file) {} 104 105 #endif 106 107 #endif /* #ifdef __KERNEL__ */ 108 109 #endif /* #ifndef _LINUX_EVENTPOLL_H */ 110 111