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  */
eventpoll_release(struct file * file)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 */
ep_op_has_event(int op)60 static inline int ep_op_has_event(int op)
61 {
62 	return op != EPOLL_CTL_DEL;
63 }
64 
65 #else
66 
eventpoll_release(struct file * file)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 *
epoll_put_uevent(__poll_t revents,__u64 data,struct epoll_event __user * uevent)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