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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/fcntl.h>
13#include <linux/wait.h>
14#include <linux/err.h>
15#include <linux/percpu-defs.h>
16#include <linux/percpu.h>
17
18/*
19 * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
20 * new flags, since they might collide with O_* ones. We want
21 * to re-use O_* flags that couldn't possibly have a meaning
22 * from eventfd, in order to leave a free define-space for
23 * shared O_* flags.
24 */
25#define EFD_SEMAPHORE (1 << 0)
26#define EFD_CLOEXEC O_CLOEXEC
27#define EFD_NONBLOCK O_NONBLOCK
28
29#define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
30#define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE)
31
32struct eventfd_ctx;
33struct file;
34
35#ifdef CONFIG_EVENTFD
36
37void eventfd_ctx_put(struct eventfd_ctx *ctx);
38struct file *eventfd_fget(int fd);
39struct eventfd_ctx *eventfd_ctx_fdget(int fd);
40struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
41__u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n);
42int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,
43 __u64 *cnt);
44void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt);
45
46DECLARE_PER_CPU(int, eventfd_wake_count);
47
48static inline bool eventfd_signal_count(void)
49{
50 return this_cpu_read(eventfd_wake_count);
51}
52
53#else /* CONFIG_EVENTFD */
54
55/*
56 * Ugly ugly ugly error layer to support modules that uses eventfd but
57 * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
58 */
59
60static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
61{
62 return ERR_PTR(-ENOSYS);
63}
64
65static inline int eventfd_signal(struct eventfd_ctx *ctx, int n)
66{
67 return -ENOSYS;
68}
69
70static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
71{
72
73}
74
75static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
76 wait_queue_entry_t *wait, __u64 *cnt)
77{
78 return -ENOSYS;
79}
80
81static inline bool eventfd_signal_count(void)
82{
83 return false;
84}
85
86static inline void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt)
87{
88
89}
90
91#endif
92
93#endif /* _LINUX_EVENTFD_H */
94