LXR linux/include/linux/eventfd.h

   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
  18/*
  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
  23 * shared O_* flags.
  24 */
  25#define EFD_SEMAPHORE (1 << 0)
  26#define EFD_CLOEXEC O_CLOEXEC
  27#define EFD_NONBLOCK O_NONBLOCK
  28
  29#define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
  30#define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE)
  31
  32struct eventfd_ctx;
  33struct file;
  34
  35#ifdef CONFIG_EVENTFD
  36
  37void eventfd_ctx_put(struct eventfd_ctx *ctx);
  38struct file *eventfd_fget(int fd);
  39struct eventfd_ctx *eventfd_ctx_fdget(int fd);
  40struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
  41__u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n);
  42int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,
  43                                  __u64 *cnt);
  44void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt);
  45
  46DECLARE_PER_CPU(int, eventfd_wake_count);
  47
  48static inline bool eventfd_signal_count(void)
  49{
  50        return this_cpu_read(eventfd_wake_count);
  51}
  52
  53#else /* CONFIG_EVENTFD */
  54
  55/*
  56 * Ugly ugly ugly error layer to support modules that uses eventfd but
  57 * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
  58 */
  59
  60static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
  61{
  62        return ERR_PTR(-ENOSYS);
  63}
  64
  65static inline int eventfd_signal(struct eventfd_ctx *ctx, int n)
  66{
  67        return -ENOSYS;
  68}
  69
  70static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
  71{
  72
  73}
  74
  75static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
  76                                                wait_queue_entry_t *wait, __u64 *cnt)
  77{
  78        return -ENOSYS;
  79}
  80
  81static inline bool eventfd_signal_count(void)
  82{
  83        return false;
  84}
  85
  86static inline void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt)
  87{
  88
  89}
  90
  91#endif
  92
  93#endif /* _LINUX_EVENTFD_H */
  94
  95