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
18 /*
19 * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
20 * new flags, since they might collide with O_* ones. We want
21 * to re-use O_* flags that couldn't possibly have a meaning
22 * from eventfd, in order to leave a free define-space for
23 * shared O_* flags.
24 */
25 #define EFD_SEMAPHORE (1 << 0)
26 #define EFD_CLOEXEC O_CLOEXEC
27 #define EFD_NONBLOCK O_NONBLOCK
28
29 #define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
30 #define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE)
31
32 struct eventfd_ctx;
33 struct file;
34
35 #ifdef CONFIG_EVENTFD
36
37 void eventfd_ctx_put(struct eventfd_ctx *ctx);
38 struct file *eventfd_fget(int fd);
39 struct eventfd_ctx *eventfd_ctx_fdget(int fd);
40 struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
41 __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n);
42 __u64 eventfd_signal_mask(struct eventfd_ctx *ctx, __u64 n, unsigned mask);
43 int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,
44 __u64 *cnt);
45 void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt);
46
47 DECLARE_PER_CPU(int, eventfd_wake_count);
48
eventfd_signal_count(void)49 static inline bool eventfd_signal_count(void)
50 {
51 return this_cpu_read(eventfd_wake_count);
52 }
53
54 #else /* CONFIG_EVENTFD */
55
56 /*
57 * Ugly ugly ugly error layer to support modules that uses eventfd but
58 * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
59 */
60
eventfd_ctx_fdget(int fd)61 static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
62 {
63 return ERR_PTR(-ENOSYS);
64 }
65
eventfd_signal(struct eventfd_ctx * ctx,__u64 n)66 static inline int eventfd_signal(struct eventfd_ctx *ctx, __u64 n)
67 {
68 return -ENOSYS;
69 }
70
eventfd_signal_mask(struct eventfd_ctx * ctx,__u64 n,unsigned mask)71 static inline int eventfd_signal_mask(struct eventfd_ctx *ctx, __u64 n,
72 unsigned mask)
73 {
74 return -ENOSYS;
75 }
76
eventfd_ctx_put(struct eventfd_ctx * ctx)77 static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
78 {
79
80 }
81
eventfd_ctx_remove_wait_queue(struct eventfd_ctx * ctx,wait_queue_entry_t * wait,__u64 * cnt)82 static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
83 wait_queue_entry_t *wait, __u64 *cnt)
84 {
85 return -ENOSYS;
86 }
87
eventfd_signal_count(void)88 static inline bool eventfd_signal_count(void)
89 {
90 return false;
91 }
92
eventfd_ctx_do_read(struct eventfd_ctx * ctx,__u64 * cnt)93 static inline void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt)
94 {
95
96 }
97
98 #endif
99
100 #endif /* _LINUX_EVENTFD_H */
101
102