linux/include/linux/eventfd.h
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   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/file.h>
  13#include <linux/wait.h>
  14
  15/*
  16 * CAREFUL: Check include/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
  29#ifdef CONFIG_EVENTFD
  30
  31struct file *eventfd_file_create(unsigned int count, int flags);
  32struct eventfd_ctx *eventfd_ctx_get(struct eventfd_ctx *ctx);
  33void eventfd_ctx_put(struct eventfd_ctx *ctx);
  34struct file *eventfd_fget(int fd);
  35struct eventfd_ctx *eventfd_ctx_fdget(int fd);
  36struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
  37__u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n);
  38ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait, __u64 *cnt);
  39int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_t *wait,
  40                                  __u64 *cnt);
  41
  42#else /* CONFIG_EVENTFD */
  43
  44/*
  45 * Ugly ugly ugly error layer to support modules that uses eventfd but
  46 * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
  47 */
  48static inline struct file *eventfd_file_create(unsigned int count, int flags)
  49{
  50        return ERR_PTR(-ENOSYS);
  51}
  52
  53static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
  54{
  55        return ERR_PTR(-ENOSYS);
  56}
  57
  58static inline int eventfd_signal(struct eventfd_ctx *ctx, int n)
  59{
  60        return -ENOSYS;
  61}
  62
  63static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
  64{
  65
  66}
  67
  68static inline ssize_t eventfd_ctx_read(struct eventfd_ctx *ctx, int no_wait,
  69                                       __u64 *cnt)
  70{
  71        return -ENOSYS;
  72}
  73
  74static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
  75                                                wait_queue_t *wait, __u64 *cnt)
  76{
  77        return -ENOSYS;
  78}
  79
  80#endif
  81
  82#endif /* _LINUX_EVENTFD_H */
  83
  84
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