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