Linux kernel mirror (for testing)
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linux
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/**
45 * INIT_ERR_PTR - Init a const error pointer.
46 * @error: A negative error code.
47 *
48 * Like ERR_PTR(), but usable to initialize static variables.
49 */
50#define INIT_ERR_PTR(error) ((void *)(error))
51
52/* Return the pointer in the percpu address space. */
53#define ERR_PTR_PCPU(error) ((void __percpu *)(unsigned long)ERR_PTR(error))
54
55/* Cast an error pointer to __iomem. */
56#define IOMEM_ERR_PTR(error) (__force void __iomem *)ERR_PTR(error)
57
58/**
59 * PTR_ERR - Extract the error code from an error pointer.
60 * @ptr: An error pointer.
61 * Return: The error code within @ptr.
62 */
63static inline long __must_check PTR_ERR(__force const void *ptr)
64{
65 return (long) ptr;
66}
67
68/* Read an error pointer from the percpu address space. */
69#define PTR_ERR_PCPU(ptr) (PTR_ERR((const void *)(__force const unsigned long)(ptr)))
70
71/**
72 * IS_ERR - Detect an error pointer.
73 * @ptr: The pointer to check.
74 * Return: true if @ptr is an error pointer, false otherwise.
75 */
76static inline bool __must_check IS_ERR(__force const void *ptr)
77{
78 return IS_ERR_VALUE((unsigned long)ptr);
79}
80
81/* Read an error pointer from the percpu address space. */
82#define IS_ERR_PCPU(ptr) (IS_ERR((const void *)(__force const unsigned long)(ptr)))
83
84/**
85 * IS_ERR_OR_NULL - Detect an error pointer or a null pointer.
86 * @ptr: The pointer to check.
87 *
88 * Like IS_ERR(), but also returns true for a null pointer.
89 */
90static inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
91{
92 return unlikely(!ptr) || IS_ERR_VALUE((unsigned long)ptr);
93}
94
95/**
96 * ERR_CAST - Explicitly cast an error-valued pointer to another pointer type
97 * @ptr: The pointer to cast.
98 *
99 * Explicitly cast an error-valued pointer to another pointer type in such a
100 * way as to make it clear that's what's going on.
101 */
102static inline void * __must_check ERR_CAST(__force const void *ptr)
103{
104 /* cast away the const */
105 return (void *) ptr;
106}
107
108/**
109 * PTR_ERR_OR_ZERO - Extract the error code from a pointer if it has one.
110 * @ptr: A potential error pointer.
111 *
112 * Convenience function that can be used inside a function that returns
113 * an error code to propagate errors received as error pointers.
114 * For example, ``return PTR_ERR_OR_ZERO(ptr);`` replaces:
115 *
116 * .. code-block:: c
117 *
118 * if (IS_ERR(ptr))
119 * return PTR_ERR(ptr);
120 * else
121 * return 0;
122 *
123 * Return: The error code within @ptr if it is an error pointer; 0 otherwise.
124 */
125static inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
126{
127 if (IS_ERR(ptr))
128 return PTR_ERR(ptr);
129 else
130 return 0;
131}
132
133#endif
134
135#endif /* _LINUX_ERR_H */