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 */
ERR_PTR(long error)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 */
PTR_ERR(__force const void * ptr)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 */
IS_ERR(__force const void * ptr)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 */
IS_ERR_OR_NULL(__force const void * ptr)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 */
ERR_CAST(__force const void * ptr)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 */
PTR_ERR_OR_ZERO(__force const void * ptr)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 */
125