#ifndef _LINUX_FUTEX_H
  #define _LINUX_FUTEX_H

  #include <linux/ktime.h>

  #include <uapi/linux/futex.h>

  struct inode;
  struct mm_struct;
  struct task_struct;

  long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,

  	      u32 __user *uaddr2, u32 val2, u32 val3);

  extern int
  handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi);

  /*
   * Futexes are matched on equal values of this key.
   * The key type depends on whether it's a shared or private mapping.
   * Don't rearrange members without looking at hash_futex().
   *
   * offset is aligned to a multiple of sizeof(u32) (== 4) by definition.

   * We use the two low order bits of offset to tell what is the kind of key :
   *  00 : Private process futex (PTHREAD_PROCESS_PRIVATE)
   *       (no reference on an inode or mm)
   *  01 : Shared futex (PTHREAD_PROCESS_SHARED)
   *	mapped on a file (reference on the underlying inode)
   *  10 : Shared futex (PTHREAD_PROCESS_SHARED)
   *       (but private mapping on an mm, and reference taken on it)
  */
  
  #define FUT_OFF_INODE    1 /* We set bit 0 if key has a reference on inode */
  #define FUT_OFF_MMSHARED 2 /* We set bit 1 if key has a reference on mm */

  union futex_key {
  	struct {
  		unsigned long pgoff;
  		struct inode *inode;
  		int offset;
  	} shared;
  	struct {
  		unsigned long address;
  		struct mm_struct *mm;
  		int offset;
  	} private;
  	struct {
  		unsigned long word;
  		void *ptr;
  		int offset;
  	} both;
  };

  #define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = NULL } }

  #ifdef CONFIG_FUTEX
  extern void exit_robust_list(struct task_struct *curr);

  extern void exit_pi_state_list(struct task_struct *curr);

  #ifdef CONFIG_HAVE_FUTEX_CMPXCHG
  #define futex_cmpxchg_enabled 1
  #else

  extern int futex_cmpxchg_enabled;

  #endif

  #else
  static inline void exit_robust_list(struct task_struct *curr)
  {
  }

  static inline void exit_pi_state_list(struct task_struct *curr)
  {
  }

  #endif

  #endif