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
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