LXR linux/include/linux/eventfd.h

   1/*
   2 *  include/linux/eventfd.h
   3 *
   4 *  Copyright (C) 2007  Davide Libenzi <davidel@xmailserver.org>
   5 *
   6 */
   7
   8#ifndef _LINUX_EVENTFD_H
   9#define _LINUX_EVENTFD_H
  10
  11#include <linux/fcntl.h>
  12#include <linux/wait.h>
  13
  14/*
  15 * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
  16 * new flags, since they might collide with O_* ones. We want
  17 * to re-use O_* flags that couldn't possibly have a meaning
  18 * from eventfd, in order to leave a free define-space for
  19 * shared O_* flags.
  20 */
  21#define EFD_SEMAPHORE (1 << 0)
  22#define EFD_CLOEXEC O_CLOEXEC
  23#define EFD_NONBLOCK O_NONBLOCK
  24
  25#define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
  26#define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE)
  27
  28struct file;
  29
  30#ifdef CONFIG_EVENTFD
  31
  32struct file *eventfd_file_create(unsigned int count, int flags);
  33struct eventfd_ctx *eventfd_ctx_get(struct eventfd_ctx *ctx);
  34void eventfd_ctx_put(struct eventfd_ctx *ctx);
  35struct file *eventfd_fget(int fd);
  36struct eventfd_ctx *eventfd_ctx_fdget(int fd);
  37struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
  38__u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n);
  39ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait, __u64 *cnt);
  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 */
  49static inline struct file *eventfd_file_create(unsigned int count, int flags)
  50{
  51        return ERR_PTR(-ENOSYS);
  52}
  53
  54static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
  55{
  56        return ERR_PTR(-ENOSYS);
  57}
  58
  59static inline int eventfd_signal(struct eventfd_ctx *ctx, int n)
  60{
  61        return -ENOSYS;
  62}
  63
  64static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
  65{
  66
  67}
  68
  69static inline ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait,
  70                                       __u64 *cnt)
  71{
  72        return -ENOSYS;
  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
  81#endif
  82
  83#endif /* _LINUX_EVENTFD_H */
  84
  85