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
  15/*
  16 * CAREFUL: Check include/uapi/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
  29struct file;
  30
  31#ifdef CONFIG_EVENTFD
  32
  33struct file *eventfd_file_create(unsigned int count, int flags);
  34struct eventfd_ctx *eventfd_ctx_get(struct eventfd_ctx *ctx);
  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);
  40ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait, __u64 *cnt);
  41int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,
  42                                  __u64 *cnt);
  43
  44#else /* CONFIG_EVENTFD */
  45
  46/*
  47 * Ugly ugly ugly error layer to support modules that uses eventfd but
  48 * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
  49 */
  50static inline struct file *eventfd_file_create(unsigned int count, int flags)
  51{
  52        return ERR_PTR(-ENOSYS);
  53}
  54
  55static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
  56{
  57        return ERR_PTR(-ENOSYS);
  58}
  59
  60static inline int eventfd_signal(struct eventfd_ctx *ctx, int n)
  61{
  62        return -ENOSYS;
  63}
  64
  65static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
  66{
  67
  68}
  69
  70static inline ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait,
  71                                       __u64 *cnt)
  72{
  73        return -ENOSYS;
  74}
  75
  76static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
  77                                                wait_queue_entry_t *wait, __u64 *cnt)
  78{
  79        return -ENOSYS;
  80}
  81
  82#endif
  83
  84#endif /* _LINUX_EVENTFD_H */
  85
  86