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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#include <linux/sched.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_SEMAPHORE (1 << 0)
27#define EFD_CLOEXEC O_CLOEXEC
28#define EFD_NONBLOCK O_NONBLOCK
29
30#define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
31#define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE)
32
33struct eventfd_ctx;
34struct file;
35
36#ifdef CONFIG_EVENTFD
37
38void eventfd_ctx_put(struct eventfd_ctx *ctx);
39struct file *eventfd_fget(int fd);
40struct eventfd_ctx *eventfd_ctx_fdget(int fd);
41struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
42__u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n);
43__u64 eventfd_signal_mask(struct eventfd_ctx *ctx, __u64 n, unsigned mask);
44int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,
45 __u64 *cnt);
46void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt);
47
48static inline bool eventfd_signal_allowed(void)
49{
50 return !current->in_eventfd;
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, __u64 n)
66{
67 return -ENOSYS;
68}
69
70static inline int eventfd_signal_mask(struct eventfd_ctx *ctx, __u64 n,
71 unsigned mask)
72{
73 return -ENOSYS;
74}
75
76static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
77{
78
79}
80
81static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
82 wait_queue_entry_t *wait, __u64 *cnt)
83{
84 return -ENOSYS;
85}
86
87static inline bool eventfd_signal_allowed(void)
88{
89 return true;
90}
91
92static inline void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt)
93{
94
95}
96
97#endif
98
99#endif /* _LINUX_EVENTFD_H */
100