LXR linux/tools/include/linux/err.h

   1#ifndef __TOOLS_LINUX_ERR_H
   2#define __TOOLS_LINUX_ERR_H
   3
   4#include <linux/compiler.h>
   5#include <linux/types.h>
   6
   7#include <asm/errno.h>
   8
   9/*
  10 * Original kernel header comment:
  11 *
  12 * Kernel pointers have redundant information, so we can use a
  13 * scheme where we can return either an error code or a normal
  14 * pointer with the same return value.
  15 *
  16 * This should be a per-architecture thing, to allow different
  17 * error and pointer decisions.
  18 *
  19 * Userspace note:
  20 * The same principle works for userspace, because 'error' pointers
  21 * fall down to the unused hole far from user space, as described
  22 * in Documentation/x86/x86_64/mm.txt for x86_64 arch:
  23 *
  24 * 0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm hole caused by [48:63] sign extension
  25 * ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole
  26 *
  27 * It should be the same case for other architectures, because
  28 * this code is used in generic kernel code.
  29 */
  30#define MAX_ERRNO       4095
  31
  32#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)
  33
  34static inline void * __must_check ERR_PTR(long error_)
  35{
  36        return (void *) error_;
  37}
  38
  39static inline long __must_check PTR_ERR(__force const void *ptr)
  40{
  41        return (long) ptr;
  42}
  43
  44static inline bool __must_check IS_ERR(__force const void *ptr)
  45{
  46        return IS_ERR_VALUE((unsigned long)ptr);
  47}
  48
  49#endif /* _LINUX_ERR_H */
  50