include/linux/err.h

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