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