include/linux/err.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_ERR_H
   3 #define _LINUX_ERR_H
   4
   5 #include <linux/compiler.h>
   6 #include <linux/types.h>
   7
   8 #include <asm/errno.h>
   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 normal
  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 /**
  23  * IS_ERR_VALUE - Detect an error pointer.
  24  * @x: The pointer to check.
  25  *
  26  * Like IS_ERR(), but does not generate a compiler warning if result is unused.
  27  */
  28 #define IS_ERR_VALUE(x) unlikely((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO)
  29
  30 /**
  31  * ERR_PTR - Create an error pointer.
  32  * @error: A negative error code.
  33  *
  34  * Encodes @error into a pointer value. Users should consider the result
  35  * opaque and not assume anything about how the error is encoded.
  36  *
  37  * Return: A pointer with @error encoded within its value.
  38  */
  39 static inline void * __must_check ERR_PTR(long error)
  40 {
  41         return (void *) error;
  42 }
  43
  44 /* Return the pointer in the percpu address space. */
  45 #define ERR_PTR_PCPU(error) ((void __percpu *)(unsigned long)ERR_PTR(error))
  46
  47 /**
  48  * PTR_ERR - Extract the error code from an error pointer.
  49  * @ptr: An error pointer.
  50  * Return: The error code within @ptr.
  51  */
  52 static inline long __must_check PTR_ERR(__force const void *ptr)
  53 {
  54         return (long) ptr;
  55 }
  56
  57 /* Read an error pointer from the percpu address space. */
  58 #define PTR_ERR_PCPU(ptr) (PTR_ERR((const void *)(__force const unsigned long)(ptr)))
  59
  60 /**
  61  * IS_ERR - Detect an error pointer.
  62  * @ptr: The pointer to check.
  63  * Return: true if @ptr is an error pointer, false otherwise.
  64  */
  65 static inline bool __must_check IS_ERR(__force const void *ptr)
  66 {
  67         return IS_ERR_VALUE((unsigned long)ptr);
  68 }
  69
  70 /* Read an error pointer from the percpu address space. */
  71 #define IS_ERR_PCPU(ptr) (IS_ERR((const void *)(__force const unsigned long)(ptr)))
  72
  73 /**
  74  * IS_ERR_OR_NULL - Detect an error pointer or a null pointer.
  75  * @ptr: The pointer to check.
  76  *
  77  * Like IS_ERR(), but also returns true for a null pointer.
  78  */
  79 static inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
  80 {
  81         return unlikely(!ptr) || IS_ERR_VALUE((unsigned long)ptr);
  82 }
  83
  84 /**
  85  * ERR_CAST - Explicitly cast an error-valued pointer to another pointer type
  86  * @ptr: The pointer to cast.
  87  *
  88  * Explicitly cast an error-valued pointer to another pointer type in such a
  89  * way as to make it clear that's what's going on.
  90  */
  91 static inline void * __must_check ERR_CAST(__force const void *ptr)
  92 {
  93         /* cast away the const */
  94         return (void *) ptr;
  95 }
  96
  97 /**
  98  * PTR_ERR_OR_ZERO - Extract the error code from a pointer if it has one.
  99  * @ptr: A potential error pointer.
 100  *
 101  * Convenience function that can be used inside a function that returns
 102  * an error code to propagate errors received as error pointers.
 103  * For example, ``return PTR_ERR_OR_ZERO(ptr);`` replaces:
 104  *
 105  * .. code-block:: c
 106  *
 107  *      if (IS_ERR(ptr))
 108  *              return PTR_ERR(ptr);
 109  *      else
 110  *              return 0;
 111  *
 112  * Return: The error code within @ptr if it is an error pointer; 0 otherwise.
 113  */
 114 static inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
 115 {
 116         if (IS_ERR(ptr))
 117                 return PTR_ERR(ptr);
 118         else
 119                 return 0;
 120 }
 121
 122 #endif
 123
 124 #endif /* _LINUX_ERR_H */