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 */
39static 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/* Cast an error pointer to __iomem. */
48#define IOMEM_ERR_PTR(error) (__force void __iomem *)ERR_PTR(error)
49
50/**
51 * PTR_ERR - Extract the error code from an error pointer.
52 * @ptr: An error pointer.
53 * Return: The error code within @ptr.
54 */
55static inline long __must_check PTR_ERR(__force const void *ptr)
56{
57 return (long) ptr;
58}
59
60/* Read an error pointer from the percpu address space. */
61#define PTR_ERR_PCPU(ptr) (PTR_ERR((const void *)(__force const unsigned long)(ptr)))
62
63/**
64 * IS_ERR - Detect an error pointer.
65 * @ptr: The pointer to check.
66 * Return: true if @ptr is an error pointer, false otherwise.
67 */
68static inline bool __must_check IS_ERR(__force const void *ptr)
69{
70 return IS_ERR_VALUE((unsigned long)ptr);
71}
72
73/* Read an error pointer from the percpu address space. */
74#define IS_ERR_PCPU(ptr) (IS_ERR((const void *)(__force const unsigned long)(ptr)))
75
76/**
77 * IS_ERR_OR_NULL - Detect an error pointer or a null pointer.
78 * @ptr: The pointer to check.
79 *
80 * Like IS_ERR(), but also returns true for a null pointer.
81 */
82static inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
83{
84 return unlikely(!ptr) || IS_ERR_VALUE((unsigned long)ptr);
85}
86
87/**
88 * ERR_CAST - Explicitly cast an error-valued pointer to another pointer type
89 * @ptr: The pointer to cast.
90 *
91 * Explicitly cast an error-valued pointer to another pointer type in such a
92 * way as to make it clear that's what's going on.
93 */
94static inline void * __must_check ERR_CAST(__force const void *ptr)
95{
96 /* cast away the const */
97 return (void *) ptr;
98}
99
100/**
101 * PTR_ERR_OR_ZERO - Extract the error code from a pointer if it has one.
102 * @ptr: A potential error pointer.
103 *
104 * Convenience function that can be used inside a function that returns
105 * an error code to propagate errors received as error pointers.
106 * For example, ``return PTR_ERR_OR_ZERO(ptr);`` replaces:
107 *
108 * .. code-block:: c
109 *
110 * if (IS_ERR(ptr))
111 * return PTR_ERR(ptr);
112 * else
113 * return 0;
114 *
115 * Return: The error code within @ptr if it is an error pointer; 0 otherwise.
116 */
117static inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
118{
119 if (IS_ERR(ptr))
120 return PTR_ERR(ptr);
121 else
122 return 0;
123}
124
125#endif
126
127#endif /* _LINUX_ERR_H */
128