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