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err.h: Add missing kerneldocs for error pointer functions

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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
This commit is contained in:
James Seo 2023-05-09 10:55:46 -07:00 committed by Jonathan Corbet
parent 34d9f62e04
commit 4d744ce9d5
1 changed files with 48 additions and 0 deletions
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48
include/linux/err.h
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@ -19,23 +19,54 @@
#ifndef __ASSEMBLY__
/**
* IS_ERR_VALUE - Detect an error pointer.
* @x: The pointer to check.
*
* Like IS_ERR(), but does not generate a compiler warning if result is unused.
*/
#define IS_ERR_VALUE(x) unlikely((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO)
/**
* ERR_PTR - Create an error pointer.
* @error: A negative error code.
*
* Encodes @error into a pointer value. Users should consider the result
* opaque and not assume anything about how the error is encoded.
*
* Return: A pointer with @error encoded within its value.
*/
static inline void * __must_check ERR_PTR(long error)
{
return (void *) error;
}
/**
* PTR_ERR - Extract the error code from an error pointer.
* @ptr: An error pointer.
* Return: The error code within @ptr.
*/
static inline long __must_check PTR_ERR(__force const void *ptr)
{
return (long) ptr;
}
/**
* IS_ERR - Detect an error pointer.
* @ptr: The pointer to check.
* Return: true if @ptr is an error pointer, false otherwise.
*/
static inline bool __must_check IS_ERR(__force const void *ptr)
{
return IS_ERR_VALUE((unsigned long)ptr);
}
/**
* IS_ERR_OR_NULL - Detect an error pointer or a null pointer.
* @ptr: The pointer to check.
*
* Like IS_ERR(), but also returns true for a null pointer.
*/
static inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
{
return unlikely(!ptr) || IS_ERR_VALUE((unsigned long)ptr);
@ -54,6 +85,23 @@ static inline void * __must_check ERR_CAST(__force const void *ptr)
return (void *) ptr;
}
/**
* PTR_ERR_OR_ZERO - Extract the error code from a pointer if it has one.
* @ptr: A potential error pointer.
*
* Convenience function that can be used inside a function that returns
* an error code to propagate errors received as error pointers.
* For example, ``return PTR_ERR_OR_ZERO(ptr);`` replaces:
*
* .. code-block:: c
*
* if (IS_ERR(ptr))
* return PTR_ERR(ptr);
* else
* return 0;
*
* Return: The error code within @ptr if it is an error pointer; 0 otherwise.
*/
static inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
{
if (IS_ERR(ptr))