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
  34 static inline void * __must_check ERR_PTR(long error_)
  35 {
  36         return (void *) error_;
  37 }
  38
  39 static inline long __must_check PTR_ERR(__force const void *ptr)
  40 {
  41         return (long) ptr;
  42 }
  43
  44 static inline bool __must_check IS_ERR(__force const void *ptr)
  45 {
  46         return IS_ERR_VALUE((unsigned long)ptr);
  47 }
  48
  49 static inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
  50 {
  51         return unlikely(!ptr) || IS_ERR_VALUE((unsigned long)ptr);
  52 }
  53
  54 #endif /* _LINUX_ERR_H */