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@xxxxxxxxxx>
---
include/linux/err.h | 48 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 48 insertions(+)
diff --git a/include/linux/err.h b/include/linux/err.h
index a139c64aef2a..c804118ae73d 100644
--- a/include/linux/err.h
+++ b/include/linux/err.h
@@ -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))
--
2.34.1
