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 <[email protected]> 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 /* Copy ready events to userspace */ 29 int epoll_sendevents(struct file *file, struct epoll_event __user *events, 30 int maxevents); 31 32 /* 33 * This is called from inside fs/file_table.c:__fput() to unlink files 34 * from the eventpoll interface. We need to have this facility to cleanup 35 * correctly files that are closed without being removed from the eventpoll 36 * interface. 37 */ 38 static inline void eventpoll_release(struct file *file) 39 { 40 41 /* 42 * Fast check to avoid the get/release of the semaphore. Since 43 * we're doing this outside the semaphore lock, it might return 44 * false negatives, but we don't care. It'll help in 99.99% of cases 45 * to avoid the semaphore lock. False positives simply cannot happen 46 * because the file in on the way to be removed and nobody ( but 47 * eventpoll ) has still a reference to this file. 48 */ 49 if (likely(!READ_ONCE(file->f_ep))) 50 return; 51 52 /* 53 * The file is being closed while it is still linked to an epoll 54 * descriptor. We need to handle this by correctly unlinking it 55 * from its containers. 56 */ 57 eventpoll_release_file(file); 58 } 59 60 int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds, 61 bool nonblock); 62 63 /* Tells if the epoll_ctl(2) operation needs an event copy from userspace */ 64 static inline int ep_op_has_event(int op) 65 { 66 return op != EPOLL_CTL_DEL; 67 } 68 69 #else 70 71 static inline void eventpoll_release(struct file *file) {} 72 73 #endif 74 75 #if defined(CONFIG_ARM) && defined(CONFIG_OABI_COMPAT) 76 /* ARM OABI has an incompatible struct layout and needs a special handler */ 77 extern struct epoll_event __user * 78 epoll_put_uevent(__poll_t revents, __u64 data, 79 struct epoll_event __user *uevent); 80 #else 81 static inline struct epoll_event __user * 82 epoll_put_uevent(__poll_t revents, __u64 data, 83 struct epoll_event __user *uevent) 84 { 85 if (__put_user(revents, &uevent->events) || 86 __put_user(data, &uevent->data)) 87 return NULL; 88 89 return uevent+1; 90 } 91 #endif 92 93 #endif /* #ifndef _LINUX_EVENTPOLL_H */ 94