forked from mirrors/linux
4d744ce9d5
Add kerneldocs for ERR_PTR(), PTR_ERR(), PTR_ERR_OR_ZERO(), IS_ERR(), and IS_ERR_OR_NULL(). Doing so will help convert hundreds of mentions of them in existing documentation into automatic cross-references. Also add kerneldocs for IS_ERR_VALUE(). Doing so adds no automatic cross-references, but this macro has a slightly different use case than the functionally similar IS_ERR(), and documenting it may be helpful to readers who encounter it in existing code. ERR_CAST() already has kerneldocs and has not been touched. Signed-off-by: James Seo <james@equiv.tech> Signed-off-by: Jonathan Corbet <corbet@lwn.net> Link: https://lore.kernel.org/r/20230509175543.2065835-3-james@equiv.tech
115 lines
2.8 KiB
C
115 lines
2.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_ERR_H
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#define _LINUX_ERR_H
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#include <linux/compiler.h>
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#include <linux/types.h>
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#include <asm/errno.h>
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/*
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* Kernel pointers have redundant information, so we can use a
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* scheme where we can return either an error code or a normal
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* pointer with the same return value.
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*
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* This should be a per-architecture thing, to allow different
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* error and pointer decisions.
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*/
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#define MAX_ERRNO 4095
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#ifndef __ASSEMBLY__
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/**
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* IS_ERR_VALUE - Detect an error pointer.
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* @x: The pointer to check.
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*
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* Like IS_ERR(), but does not generate a compiler warning if result is unused.
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*/
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#define IS_ERR_VALUE(x) unlikely((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO)
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/**
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* ERR_PTR - Create an error pointer.
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* @error: A negative error code.
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*
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* Encodes @error into a pointer value. Users should consider the result
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* opaque and not assume anything about how the error is encoded.
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*
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* Return: A pointer with @error encoded within its value.
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*/
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static inline void * __must_check ERR_PTR(long error)
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{
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return (void *) error;
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}
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/**
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* PTR_ERR - Extract the error code from an error pointer.
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* @ptr: An error pointer.
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* Return: The error code within @ptr.
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*/
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static inline long __must_check PTR_ERR(__force const void *ptr)
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{
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return (long) ptr;
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}
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/**
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* IS_ERR - Detect an error pointer.
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* @ptr: The pointer to check.
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* Return: true if @ptr is an error pointer, false otherwise.
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*/
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static inline bool __must_check IS_ERR(__force const void *ptr)
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{
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return IS_ERR_VALUE((unsigned long)ptr);
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}
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/**
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* IS_ERR_OR_NULL - Detect an error pointer or a null pointer.
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* @ptr: The pointer to check.
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*
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* Like IS_ERR(), but also returns true for a null pointer.
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*/
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static inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
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{
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return unlikely(!ptr) || IS_ERR_VALUE((unsigned long)ptr);
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}
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/**
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* ERR_CAST - Explicitly cast an error-valued pointer to another pointer type
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* @ptr: The pointer to cast.
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*
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* Explicitly cast an error-valued pointer to another pointer type in such a
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* way as to make it clear that's what's going on.
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*/
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static inline void * __must_check ERR_CAST(__force const void *ptr)
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{
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/* cast away the const */
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return (void *) ptr;
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}
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/**
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* PTR_ERR_OR_ZERO - Extract the error code from a pointer if it has one.
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* @ptr: A potential error pointer.
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*
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* Convenience function that can be used inside a function that returns
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* an error code to propagate errors received as error pointers.
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* For example, ``return PTR_ERR_OR_ZERO(ptr);`` replaces:
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*
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* .. code-block:: c
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*
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* if (IS_ERR(ptr))
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* return PTR_ERR(ptr);
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* else
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* return 0;
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*
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* Return: The error code within @ptr if it is an error pointer; 0 otherwise.
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*/
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static inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
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{
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if (IS_ERR(ptr))
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return PTR_ERR(ptr);
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else
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return 0;
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}
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#endif
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#endif /* _LINUX_ERR_H */
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