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1 /*
2 * include/linux/eventfd.h
3 *
4 * Copyright (C) 2007 Davide Libenzi <davidel@xmailserver.org>
5 *
6 */
7
8 #ifndef _LINUX_EVENTFD_H
9 #define _LINUX_EVENTFD_H
10
11 #include <linux/fcntl.h>
12 #include <linux/wait.h>
13
14 /*
15 * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
16 * new flags, since they might collide with O_* ones. We want
17 * to re-use O_* flags that couldn't possibly have a meaning
18 * from eventfd, in order to leave a free define-space for
19 * shared O_* flags.
20 */
21 #define EFD_SEMAPHORE (1 << 0)
22 #define EFD_CLOEXEC O_CLOEXEC
23 #define EFD_NONBLOCK O_NONBLOCK
24
25 #define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
26 #define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE)
27
28 struct file;
29
30 #ifdef CONFIG_EVENTFD
31
32 struct file *eventfd_file_create(unsigned int count, int flags);
33 struct eventfd_ctx *eventfd_ctx_get(struct eventfd_ctx *ctx);
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 __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n);
39 ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait, __u64 *cnt);
40 int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_t *wait,
41 __u64 *cnt);
42
43 #else /* CONFIG_EVENTFD */
44
45 /*
46 * Ugly ugly ugly error layer to support modules that uses eventfd but
47 * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
48 */
49 static inline struct file *eventfd_file_create(unsigned int count, int flags)
50 {
51 return ERR_PTR(-ENOSYS);
52 }
53
54 static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
55 {
56 return ERR_PTR(-ENOSYS);
57 }
58
59 static inline int eventfd_signal(struct eventfd_ctx *ctx, int n)
60 {
61 return -ENOSYS;
62 }
63
64 static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
65 {
66
67 }
68
69 static inline ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait,
70 __u64 *cnt)
71 {
72 return -ENOSYS;
73 }
74
75 static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
76 wait_queue_t *wait, __u64 *cnt)
77 {
78 return -ENOSYS;
79 }
80
81 #endif
82
83 #endif /* _LINUX_EVENTFD_H */
84