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