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
33 struct eventfd_ctx;
34 struct file;
35
36 #ifdef CONFIG_EVENTFD
37
38 void eventfd_ctx_put(struct eventfd_ctx *ctx);
39 struct file *eventfd_fget(int fd);
40 struct eventfd_ctx *eventfd_ctx_fdget(int fd);
41 struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
42 __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n);
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
eventfd_signal_allowed(void)47 static inline bool eventfd_signal_allowed(void)
48 {
49 return !current->in_eventfd_signal;
50 }
51
52 #else /* CONFIG_EVENTFD */
53
54 /*
55 * Ugly ugly ugly error layer to support modules that uses eventfd but
56 * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
57 */
58
eventfd_ctx_fdget(int fd)59 static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
60 {
61 return ERR_PTR(-ENOSYS);
62 }
63
eventfd_signal(struct eventfd_ctx * ctx,int n)64 static inline int eventfd_signal(struct eventfd_ctx *ctx, int n)
65 {
66 return -ENOSYS;
67 }
68
eventfd_ctx_put(struct eventfd_ctx * ctx)69 static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
70 {
71
72 }
73
eventfd_ctx_remove_wait_queue(struct eventfd_ctx * ctx,wait_queue_entry_t * wait,__u64 * cnt)74 static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
75 wait_queue_entry_t *wait, __u64 *cnt)
76 {
77 return -ENOSYS;
78 }
79
eventfd_signal_allowed(void)80 static inline bool eventfd_signal_allowed(void)
81 {
82 return true;
83 }
84
eventfd_ctx_do_read(struct eventfd_ctx * ctx,__u64 * cnt)85 static inline void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt)
86 {
87
88 }
89
90 #endif
91
92 #endif /* _LINUX_EVENTFD_H */
93
94