err.h

  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 */
 39static 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 */
 63static 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 */
 76static 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 */
 90static 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 */
102static 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 */
125static 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 */