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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * include/linux/eventfd.h
4 *
5 * Copyright (C) 2007 Davide Libenzi <davidel@xmailserver.org>
6 *
7 */
8
9#ifndef _LINUX_EVENTFD_H
10#define _LINUX_EVENTFD_H
11
12#include <linux/wait.h>
13#include <linux/err.h>
14#include <linux/percpu-defs.h>
15#include <linux/percpu.h>
16#include <linux/sched.h>
17#include <uapi/linux/eventfd.h>
18
19/*
20 * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
21 * new flags, since they might collide with O_* ones. We want
22 * to re-use O_* flags that couldn't possibly have a meaning
23 * from eventfd, in order to leave a free define-space for
24 * shared O_* flags.
25 */
26#define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
27#define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE)
28
29struct eventfd_ctx;
30struct file;
31
32#ifdef CONFIG_EVENTFD
33
34void eventfd_ctx_put(struct eventfd_ctx *ctx);
35struct file *eventfd_fget(int fd);
36struct eventfd_ctx *eventfd_ctx_fdget(int fd);
37struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
38__u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n);
39__u64 eventfd_signal_mask(struct eventfd_ctx *ctx, __u64 n, __poll_t mask);
40int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,
41 __u64 *cnt);
42void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt);
43
44static inline bool eventfd_signal_allowed(void)
45{
46 return !current->in_eventfd;
47}
48
49#else /* CONFIG_EVENTFD */
50
51/*
52 * Ugly ugly ugly error layer to support modules that uses eventfd but
53 * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
54 */
55
56static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
57{
58 return ERR_PTR(-ENOSYS);
59}
60
61static inline int eventfd_signal(struct eventfd_ctx *ctx, __u64 n)
62{
63 return -ENOSYS;
64}
65
66static inline int eventfd_signal_mask(struct eventfd_ctx *ctx, __u64 n,
67 unsigned mask)
68{
69 return -ENOSYS;
70}
71
72static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
73{
74
75}
76
77static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
78 wait_queue_entry_t *wait, __u64 *cnt)
79{
80 return -ENOSYS;
81}
82
83static inline bool eventfd_signal_allowed(void)
84{
85 return true;
86}
87
88static inline void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt)
89{
90
91}
92
93#endif
94
95#endif /* _LINUX_EVENTFD_H */
96