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 
ERR_PTR(long error)24 static inline void *ERR_PTR(long error)
25 {
26 	return (void *)(CONFIG_ERR_PTR_OFFSET + error);
27 }
28 
PTR_ERR(const void * ptr)29 static inline long PTR_ERR(const void *ptr)
30 {
31 	return ((long)ptr - CONFIG_ERR_PTR_OFFSET);
32 }
33 
IS_ERR(const void * ptr)34 static inline long IS_ERR(const void *ptr)
35 {
36 	return IS_ERR_VALUE((unsigned long)PTR_ERR(ptr));
37 }
38 
IS_ERR_OR_NULL(const void * ptr)39 static 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  */
ERR_CAST(__force const void * ptr)51 static 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