/* SPDX-License-Identifier: GPL-2.0 */

  /*
   *  include/linux/eventfd.h
   *
   *  Copyright (C) 2007  Davide Libenzi <davidel@xmailserver.org>
   *
   */
  
  #ifndef _LINUX_EVENTFD_H
  #define _LINUX_EVENTFD_H

  #include <linux/fcntl.h>

  #include <linux/wait.h>

  #include <linux/err.h>

  #include <linux/percpu-defs.h>
  #include <linux/percpu.h>

  /*

   * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining

   * new flags, since they might collide with O_* ones. We want
   * to re-use O_* flags that couldn't possibly have a meaning
   * from eventfd, in order to leave a free define-space for
   * shared O_* flags.
   */
  #define EFD_SEMAPHORE (1 << 0)

  #define EFD_CLOEXEC O_CLOEXEC

  #define EFD_NONBLOCK O_NONBLOCK

  #define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
  #define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE)

  struct eventfd_ctx;

  struct file;

  #ifdef CONFIG_EVENTFD

  void eventfd_ctx_put(struct eventfd_ctx *ctx);

  struct file *eventfd_fget(int fd);

  struct eventfd_ctx *eventfd_ctx_fdget(int fd);
  struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);

  __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n);

  int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,

  				  __u64 *cnt);

  DECLARE_PER_CPU(int, eventfd_wake_count);
  
  static inline bool eventfd_signal_count(void)
  {
  	return this_cpu_read(eventfd_wake_count);
  }

  #else /* CONFIG_EVENTFD */

  /*
   * Ugly ugly ugly error layer to support modules that uses eventfd but
   * pretend to work in !CONFIG_EVENTFD configurations. Namely, AIO.
   */

  static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
  {
  	return ERR_PTR(-ENOSYS);
  }
  
  static inline int eventfd_signal(struct eventfd_ctx *ctx, int n)
  {
  	return -ENOSYS;
  }
  
  static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
  {
  
  }

  static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,

  						wait_queue_entry_t *wait, __u64 *cnt)

  {
  	return -ENOSYS;
  }

  static inline bool eventfd_signal_count(void)
  {
  	return false;
  }

  #endif

  #endif /* _LINUX_EVENTFD_H */