#ifndef _LINUX_ERR_H
  #define _LINUX_ERR_H
  
  #include <linux/compiler.h>
  
  #include <asm/errno.h>
  
  /*
   * Kernel pointers have redundant information, so we can use a
   * scheme where we can return either an error code or a dentry
   * pointer with the same return value.
   *
   * This should be a per-architecture thing, to allow different
   * error and pointer decisions.
   */

  #define MAX_ERRNO	4095

  #ifndef __ASSEMBLY__

  #define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)

  static inline void * __must_check ERR_PTR(long error)

  {
  	return (void *) error;
  }

  static inline long __must_check PTR_ERR(const void *ptr)

  {
  	return (long) ptr;
  }

  static inline long __must_check IS_ERR(const void *ptr)

  {

  	return IS_ERR_VALUE((unsigned long)ptr);

  }

  static inline long __must_check IS_ERR_OR_NULL(const void *ptr)

  {
  	return !ptr || IS_ERR_VALUE((unsigned long)ptr);
  }

  /**
   * ERR_CAST - Explicitly cast an error-valued pointer to another pointer type
   * @ptr: The pointer to cast.
   *
   * Explicitly cast an error-valued pointer to another pointer type in such a
   * way as to make it clear that's what's going on.
   */

  static inline void * __must_check ERR_CAST(const void *ptr)

  {
  	/* cast away the const */
  	return (void *) ptr;
  }

  static inline int __must_check PTR_RET(const void *ptr)
  {
  	if (IS_ERR(ptr))
  		return PTR_ERR(ptr);
  	else
  		return 0;
  }

  #endif

  #endif /* _LINUX_ERR_H */