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 #ifndef _LINUX_EVENTPOLL_H 14 #define _LINUX_EVENTPOLL_H 15 16 #include <uapi/linux/eventpoll.h> 17 #include <uapi/linux/kcmp.h> 18 19 20 /* Forward declarations to avoid compiler errors */ 21 struct file; 22 23 24 #ifdef CONFIG_EPOLL 25 26 #ifdef CONFIG_CHECKPOINT_RESTORE 27 struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd, unsigned long toff); 28 #endif 29 30 /* Used to initialize the epoll bits inside the "struct file" */ eventpoll_init_file(struct file * file)31static inline void eventpoll_init_file(struct file *file) 32 { 33 INIT_LIST_HEAD(&file->f_ep_links); 34 INIT_LIST_HEAD(&file->f_tfile_llink); 35 } 36 37 38 /* Used to release the epoll bits inside the "struct file" */ 39 void eventpoll_release_file(struct file *file); 40 41 /* 42 * This is called from inside fs/file_table.c:__fput() to unlink files 43 * from the eventpoll interface. We need to have this facility to cleanup 44 * correctly files that are closed without being removed from the eventpoll 45 * interface. 46 */ eventpoll_release(struct file * file)47static inline void eventpoll_release(struct file *file) 48 { 49 50 /* 51 * Fast check to avoid the get/release of the semaphore. Since 52 * we're doing this outside the semaphore lock, it might return 53 * false negatives, but we don't care. It'll help in 99.99% of cases 54 * to avoid the semaphore lock. False positives simply cannot happen 55 * because the file in on the way to be removed and nobody ( but 56 * eventpoll ) has still a reference to this file. 57 */ 58 if (likely(list_empty(&file->f_ep_links))) 59 return; 60 61 /* 62 * The file is being closed while it is still linked to an epoll 63 * descriptor. We need to handle this by correctly unlinking it 64 * from its containers. 65 */ 66 eventpoll_release_file(file); 67 } 68 69 #else 70 eventpoll_init_file(struct file * file)71static inline void eventpoll_init_file(struct file *file) {} eventpoll_release(struct file * file)72static inline void eventpoll_release(struct file *file) {} 73 74 #endif 75 76 #endif /* #ifndef _LINUX_EVENTPOLL_H */ 77