1 /* SPDX-License-Identifier: GPL-2.0 */
3 * include/linux/eventfd.h
5 * Copyright (C) 2007 Davide Libenzi <davidel@xmailserver.org>
9 #ifndef _LINUX_EVENTFD_H
10 #define _LINUX_EVENTFD_H
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>
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
25 #define EFD_SEMAPHORE (1 << 0)
26 #define EFD_CLOEXEC O_CLOEXEC
27 #define EFD_NONBLOCK O_NONBLOCK
29 #define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
30 #define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE)
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,
45 void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt);
47 DECLARE_PER_CPU(int, eventfd_wake_count);
49 static inline bool eventfd_signal_count(void)
51 return this_cpu_read(eventfd_wake_count);
54 #else /* CONFIG_EVENTFD */
57 * Ugly ugly ugly error layer to support modules that uses eventfd but
58 * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
61 static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
63 return ERR_PTR(-ENOSYS);
66 static inline int eventfd_signal(struct eventfd_ctx *ctx, __u64 n)
71 static inline int eventfd_signal_mask(struct eventfd_ctx *ctx, __u64 n,
77 static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
82 static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
83 wait_queue_entry_t *wait, __u64 *cnt)
88 static inline bool eventfd_signal_count(void)
93 static inline void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt)
100 #endif /* _LINUX_EVENTFD_H */