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);
38void eventfd_signal_mask(struct eventfd_ctx *ctx, __poll_t mask);
39int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,
40 __u64 *cnt);
41void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt);
42
43static inline bool eventfd_signal_allowed(void)
44{
45 return !current->in_eventfd;
46}
47
48#else /* CONFIG_EVENTFD */
49
50/*
51 * Ugly ugly ugly error layer to support modules that uses eventfd but
52 * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
53 */
54
55static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
56{
57 return ERR_PTR(-ENOSYS);
58}
59
60static inline void eventfd_signal_mask(struct eventfd_ctx *ctx, __poll_t mask)
61{
62}
63
64static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
65{
66
67}
68
69static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
70 wait_queue_entry_t *wait, __u64 *cnt)
71{
72 return -ENOSYS;
73}
74
75static inline bool eventfd_signal_allowed(void)
76{
77 return true;
78}
79
80static inline void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt)
81{
82
83}
84
85#endif
86
87static inline void eventfd_signal(struct eventfd_ctx *ctx)
88{
89 eventfd_signal_mask(ctx, mask: 0);
90}
91
92#endif /* _LINUX_EVENTFD_H */
93
94