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
  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
  30struct eventfd_ctx;
  31struct file;
  32
  33#ifdef CONFIG_EVENTFD
  34
  35void eventfd_ctx_put(struct eventfd_ctx *ctx);
  36struct file *eventfd_fget(int fd);
  37struct eventfd_ctx *eventfd_ctx_fdget(int fd);
  38struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
  39__u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n);
  40int 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
  50static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
  51{
  52        return ERR_PTR(-ENOSYS);
  53}
  54
  55static inline int eventfd_signal(struct eventfd_ctx *ctx, int n)
  56{
  57        return -ENOSYS;
  58}
  59
  60static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
  61{
  62
  63}
  64
  65static 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