1#ifndef _LINUX_ERR_H
2#define _LINUX_ERR_H
3
4#include <linux/compiler.h>
5#include <linux/compat.h>
6
7#include <linux/errno.h>
8
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 dentry
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#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)
23
24static inline void *ERR_PTR(long error)
25{
26	return (void *)(CONFIG_ERR_PTR_OFFSET + error);
27}
28
29static inline long PTR_ERR(const void *ptr)
30{
31	return ((long)ptr - CONFIG_ERR_PTR_OFFSET);
32}
33
34static inline long IS_ERR(const void *ptr)
35{
36	return IS_ERR_VALUE((unsigned long)PTR_ERR(ptr));
37}
38
39static inline bool IS_ERR_OR_NULL(const void *ptr)
40{
41	return !ptr || IS_ERR_VALUE((unsigned long)PTR_ERR(ptr));
42}
43
44/**
45 * ERR_CAST - Explicitly cast an error-valued pointer to another pointer type
46 * @ptr: The pointer to cast.
47 *
48 * Explicitly cast an error-valued pointer to another pointer type in such a
49 * way as to make it clear that's what's going on.
50 */
51static inline void * __must_check ERR_CAST(__force const void *ptr)
52{
53	/* cast away the const */
54	return (void *) ptr;
55}
56
57#endif
58
59#endif /* _LINUX_ERR_H */
60