Linux kernel mirror (for testing)
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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 skip the slow path in the common case where the
43 * file was never attached to an epoll. Safe without file->f_lock
44 * because every f_ep writer excludes a concurrent __fput() on
45 * @file:
46 * - ep_insert() requires the file alive (refcount > 0);
47 * - ep_remove() holds @file pinned via epi_fget() across the
48 * write;
49 * - eventpoll_release_file() runs from __fput() itself.
50 * We are in __fput() here, so none of those can race us: a NULL
51 * observation truly means no epoll path has work left on @file.
52 */
53 if (likely(!READ_ONCE(file->f_ep)))
54 return;
55
56 /*
57 * The file is being closed while it is still linked to an epoll
58 * descriptor. We need to handle this by correctly unlinking it
59 * from its containers.
60 */
61 eventpoll_release_file(file);
62}
63
64int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
65 bool nonblock);
66
67/* Tells if the epoll_ctl(2) operation needs an event copy from userspace */
68static inline int ep_op_has_event(int op)
69{
70 return op != EPOLL_CTL_DEL;
71}
72
73#else
74
75static inline void eventpoll_release(struct file *file) {}
76
77#endif
78
79#if defined(CONFIG_ARM) && defined(CONFIG_OABI_COMPAT)
80/* ARM OABI has an incompatible struct layout and needs a special handler */
81extern struct epoll_event __user *
82epoll_put_uevent(__poll_t revents, __u64 data,
83 struct epoll_event __user *uevent);
84#else
85static inline struct epoll_event __user *
86epoll_put_uevent(__poll_t revents, __u64 data,
87 struct epoll_event __user *uevent)
88{
89 scoped_user_write_access_size(uevent, sizeof(*uevent), efault) {
90 unsafe_put_user(revents, &uevent->events, efault);
91 unsafe_put_user(data, &uevent->data, efault);
92 }
93 return uevent+1;
94
95efault:
96 return NULL;
97}
98#endif
99
100#endif /* #ifndef _LINUX_EVENTPOLL_H */