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 */ 39 static __always_inline void * __must_check ERR_PTR(long error) 40 { 41 return (void *) error; 42 } 43 44 /** 45 * INIT_ERR_PTR - Init a const error pointer. 46 * @error: A negative error code. 47 * 48 * Like ERR_PTR(), but usable to initialize static variables. 49 */ 50 #define INIT_ERR_PTR(error) ((void *)(error)) 51 52 /* Return the pointer in the percpu address space. */ 53 #define ERR_PTR_PCPU(error) ((void __percpu *)(unsigned long)ERR_PTR(error)) 54 55 /* Cast an error pointer to __iomem. */ 56 #define IOMEM_ERR_PTR(error) (__force void __iomem *)ERR_PTR(error) 57 58 /** 59 * PTR_ERR - Extract the error code from an error pointer. 60 * @ptr: An error pointer. 61 * Return: The error code within @ptr. 62 */ 63 static __always_inline long __must_check PTR_ERR(__force const void *ptr) 64 { 65 return (long) ptr; 66 } 67 68 /* Read an error pointer from the percpu address space. */ 69 #define PTR_ERR_PCPU(ptr) (PTR_ERR((const void *)(__force const unsigned long)(ptr))) 70 71 /** 72 * IS_ERR - Detect an error pointer. 73 * @ptr: The pointer to check. 74 * Return: true if @ptr is an error pointer, false otherwise. 75 */ 76 static __always_inline bool __must_check IS_ERR(__force const void *ptr) 77 { 78 return IS_ERR_VALUE((unsigned long)ptr); 79 } 80 81 /* Read an error pointer from the percpu address space. */ 82 #define IS_ERR_PCPU(ptr) (IS_ERR((const void *)(__force const unsigned long)(ptr))) 83 84 /** 85 * IS_ERR_OR_NULL - Detect an error pointer or a null pointer. 86 * @ptr: The pointer to check. 87 * 88 * Like IS_ERR(), but also returns true for a null pointer. 89 */ 90 static __always_inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr) 91 { 92 return unlikely(!ptr) || IS_ERR_VALUE((unsigned long)ptr); 93 } 94 95 /** 96 * ERR_CAST - Explicitly cast an error-valued pointer to another pointer type 97 * @ptr: The pointer to cast. 98 * 99 * Explicitly cast an error-valued pointer to another pointer type in such a 100 * way as to make it clear that's what's going on. 101 */ 102 static __always_inline void * __must_check ERR_CAST(__force const void *ptr) 103 { 104 /* cast away the const */ 105 return (void *) ptr; 106 } 107 108 /** 109 * PTR_ERR_OR_ZERO - Extract the error code from a pointer if it has one. 110 * @ptr: A potential error pointer. 111 * 112 * Convenience function that can be used inside a function that returns 113 * an error code to propagate errors received as error pointers. 114 * For example, ``return PTR_ERR_OR_ZERO(ptr);`` replaces: 115 * 116 * .. code-block:: c 117 * 118 * if (IS_ERR(ptr)) 119 * return PTR_ERR(ptr); 120 * else 121 * return 0; 122 * 123 * Return: The error code within @ptr if it is an error pointer; 0 otherwise. 124 */ 125 static __always_inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr) 126 { 127 if (IS_ERR(ptr)) 128 return PTR_ERR(ptr); 129 else 130 return 0; 131 } 132 133 #endif 134 135 #endif /* _LINUX_ERR_H */ 136