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  * Kernel pointers have redundant information, so we can use a
11  * scheme where we can return either an error code or a dentry
12  * pointer with the same return value.
13  *
14  * This should be a per-architecture thing, to allow different
15  * error and pointer decisions.
16  */
17 #define MAX_ERRNO	4095
18 
19 #ifndef __ASSEMBLY__
20 
21 #define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)
22 
ERR_PTR(long error)23 static inline void *ERR_PTR(long error)
24 {
25 	return (void *)(CONFIG_ERR_PTR_OFFSET + error);
26 }
27 
PTR_ERR(const void * ptr)28 static inline long PTR_ERR(const void *ptr)
29 {
30 	return ((long)ptr - CONFIG_ERR_PTR_OFFSET);
31 }
32 
IS_ERR(const void * ptr)33 static inline long IS_ERR(const void *ptr)
34 {
35 	return IS_ERR_VALUE((unsigned long)PTR_ERR(ptr));
36 }
37 
IS_ERR_OR_NULL(const void * ptr)38 static inline bool IS_ERR_OR_NULL(const void *ptr)
39 {
40 	return !ptr || IS_ERR_VALUE((unsigned long)PTR_ERR(ptr));
41 }
42 
43 /**
44  * ERR_CAST - Explicitly cast an error-valued pointer to another pointer type
45  * @ptr: The pointer to cast.
46  *
47  * Explicitly cast an error-valued pointer to another pointer type in such a
48  * way as to make it clear that's what's going on.
49  */
ERR_CAST(__force const void * ptr)50 static inline void * __must_check ERR_CAST(__force const void *ptr)
51 {
52 	/* cast away the const */
53 	return (void *) ptr;
54 }
55 
56 #endif
57 
58 #endif /* _LINUX_ERR_H */
59