1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _LINUX_ERR_H 3 #define _LINUX_ERR_H 4 5 #include "compiler.h" 6 #include "../types.h" 7 8 #include "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 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 */ 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 */ 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 */ 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 */ 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 */ 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