linux/include/linux/err.h
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   1#ifndef _LINUX_ERR_H
   2#define _LINUX_ERR_H
   3
   4#include <linux/compiler.h>
   5
   6#include <asm/errno.h>
   7
   8/*
   9 * Kernel pointers have redundant information, so we can use a
  10 * scheme where we can return either an error code or a dentry
  11 * pointer with the same return value.
  12 *
  13 * This should be a per-architecture thing, to allow different
  14 * error and pointer decisions.
  15 */
  16#define MAX_ERRNO       4095
  17
  18#ifndef __ASSEMBLY__
  19
  20#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)
  21
  22static inline void * __must_check ERR_PTR(long error)
  23{
  24        return (void *) error;
  25}
  26
  27static inline long __must_check PTR_ERR(const void *ptr)
  28{
  29        return (long) ptr;
  30}
  31
  32static inline long __must_check IS_ERR(const void *ptr)
  33{
  34        return IS_ERR_VALUE((unsigned long)ptr);
  35}
  36
  37static inline long __must_check IS_ERR_OR_NULL(const void *ptr)
  38{
  39        return !ptr || IS_ERR_VALUE((unsigned long)ptr);
  40}
  41
  42/**
  43 * ERR_CAST - Explicitly cast an error-valued pointer to another pointer type
  44 * @ptr: The pointer to cast.
  45 *
  46 * Explicitly cast an error-valued pointer to another pointer type in such a
  47 * way as to make it clear that's what's going on.
  48 */
  49static inline void * __must_check ERR_CAST(const void *ptr)
  50{
  51        /* cast away the const */
  52        return (void *) ptr;
  53}
  54
  55static inline int __must_check PTR_RET(const void *ptr)
  56{
  57        if (IS_ERR(ptr))
  58                return PTR_ERR(ptr);
  59        else
  60                return 0;
  61}
  62
  63#endif
  64
  65#endif /* _LINUX_ERR_H */
  66
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