1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 * include/linux/eventpoll.h ( Efficient event polling implementation ) 4 * Copyright (C) 2001,...,2006 Davide Libenzi 5 * 6 * Davide Libenzi <davidel@xmailserver.org> 7 */ 8 #ifndef _LINUX_EVENTPOLL_H 9 #define _LINUX_EVENTPOLL_H 10 11 #include <uapi/linux/eventpoll.h> 12 #include <uapi/linux/kcmp.h> 13 14 15 /* Forward declarations to avoid compiler errors */ 16 struct file; 17 18 19 #ifdef CONFIG_EPOLL 20 21 #ifdef CONFIG_KCMP 22 struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd, unsigned long toff); 23 #endif 24 25 /* Used to release the epoll bits inside the "struct file" */ 26 void eventpoll_release_file(struct file *file); 27 28 /* 29 * This is called from inside fs/file_table.c:__fput() to unlink files 30 * from the eventpoll interface. We need to have this facility to cleanup 31 * correctly files that are closed without being removed from the eventpoll 32 * interface. 33 */ 34 static inline void eventpoll_release(struct file *file) 35 { 36 37 /* 38 * Fast check to avoid the get/release of the semaphore. Since 39 * we're doing this outside the semaphore lock, it might return 40 * false negatives, but we don't care. It'll help in 99.99% of cases 41 * to avoid the semaphore lock. False positives simply cannot happen 42 * because the file in on the way to be removed and nobody ( but 43 * eventpoll ) has still a reference to this file. 44 */ 45 if (likely(!file->f_ep)) 46 return; 47 48 /* 49 * The file is being closed while it is still linked to an epoll 50 * descriptor. We need to handle this by correctly unlinking it 51 * from its containers. 52 */ 53 eventpoll_release_file(file); 54 } 55 56 int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds, 57 bool nonblock); 58 59 /* Tells if the epoll_ctl(2) operation needs an event copy from userspace */ 60 static inline int ep_op_has_event(int op) 61 { 62 return op != EPOLL_CTL_DEL; 63 } 64 65 #else 66 67 static inline void eventpoll_release(struct file *file) {} 68 69 #endif 70 71 #if defined(CONFIG_ARM) && defined(CONFIG_OABI_COMPAT) 72 /* ARM OABI has an incompatible struct layout and needs a special handler */ 73 extern struct epoll_event __user * 74 epoll_put_uevent(__poll_t revents, __u64 data, 75 struct epoll_event __user *uevent); 76 #else 77 static inline struct epoll_event __user * 78 epoll_put_uevent(__poll_t revents, __u64 data, 79 struct epoll_event __user *uevent) 80 { 81 if (__put_user(revents, &uevent->events) || 82 __put_user(data, &uevent->data)) 83 return NULL; 84 85 return uevent+1; 86 } 87 #endif 88 89 #endif /* #ifndef _LINUX_EVENTPOLL_H */ 90