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
16 /*
17 * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
18 * new flags, since they might collide with O_* ones. We want
19 * to re-use O_* flags that couldn't possibly have a meaning
20 * from eventfd, in order to leave a free define-space for
21 * shared O_* flags.
22 */
23 #define EFD_SEMAPHORE (1 << 0)
24 #define EFD_CLOEXEC O_CLOEXEC
25 #define EFD_NONBLOCK O_NONBLOCK
26
27 #define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
28 #define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE)
29
30 struct eventfd_ctx;
31 struct file;
32
33 #ifdef CONFIG_EVENTFD
34
35 void eventfd_ctx_put(struct eventfd_ctx *ctx);
36 struct file *eventfd_fget(int fd);
37 struct eventfd_ctx *eventfd_ctx_fdget(int fd);
38 struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
39 __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n);
40 int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_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
eventfd_ctx_fdget(int fd)50 static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
51 {
52 return ERR_PTR(-ENOSYS);
53 }
54
eventfd_signal(struct eventfd_ctx * ctx,int n)55 static inline int eventfd_signal(struct eventfd_ctx *ctx, int n)
56 {
57 return -ENOSYS;
58 }
59
eventfd_ctx_put(struct eventfd_ctx * ctx)60 static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
61 {
62
63 }
64
eventfd_ctx_remove_wait_queue(struct eventfd_ctx * ctx,wait_queue_entry_t * wait,__u64 * cnt)65 static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
66 wait_queue_entry_t *wait, __u64 *cnt)
67 {
68 return -ENOSYS;
69 }
70
71 #endif
72
73 #endif /* _LINUX_EVENTFD_H */
74
75
