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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 */
16struct file;
17
18
19#ifdef CONFIG_EPOLL
20
21#ifdef CONFIG_KCMP
22struct 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" */
26void eventpoll_release_file(struct file *file);
27
28/* Copy ready events to userspace */
29int 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 */
38static 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
60int 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 */
64static inline int ep_op_has_event(int op)
65{
66 return op != EPOLL_CTL_DEL;
67}
68
69#else
70
71static 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 */
77extern struct epoll_event __user *
78epoll_put_uevent(__poll_t revents, __u64 data,
79 struct epoll_event __user *uevent);
80#else
81static inline struct epoll_event __user *
82epoll_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 */