include/linux/err.h

   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
  22 static inline void *ERR_PTR(long error)
  23 {
  24         return (void *) error;
  25 }
  26
  27 static inline long PTR_ERR(const void *ptr)
  28 {
  29         return (long) ptr;
  30 }
  31
  32 static inline long IS_ERR(const void *ptr)
  33 {
  34         return IS_ERR_VALUE((unsigned long)ptr);
  35 }
  36
  37 static inline long 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  */
  49 static inline void *ERR_CAST(const void *ptr)
  50 {
  51         /* cast away the const */
  52         return (void *) ptr;
  53 }
  54
  55 #endif
  56
  57 #endif /* _LINUX_ERR_H */