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
29 struct eventfd_ctx;
30 struct file;
31
32 #ifdef CONFIG_EVENTFD
33
34 void eventfd_ctx_put(struct eventfd_ctx *ctx);
35 struct file *eventfd_fget(int fd);
36 struct eventfd_ctx *eventfd_ctx_fdget(int fd);
37 struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
38 void eventfd_signal_mask(struct eventfd_ctx *ctx, __poll_t mask);
39 int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,
40 __u64 *cnt);
41 void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt);
42
43 static 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
55 static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
56 {
57 return ERR_PTR(-ENOSYS);
58 }
59
60 static inline void eventfd_signal_mask(struct eventfd_ctx *ctx, __poll_t mask)
61 {
62 }
63
64 static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
65 {
66
67 }
68
69 static 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
75 static inline bool eventfd_signal_allowed(void)
76 {
77 return true;
78 }
79
80 static inline void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt)
81 {
82
83 }
84
85 #endif
86
87 static inline void eventfd_signal(struct eventfd_ctx *ctx)
88 {
89 eventfd_signal_mask(ctx, 0);
90 }
91
92 #endif /* _LINUX_EVENTFD_H */
93
94
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