1 files changed, 76 insertions, 6 deletions

diff --git a/include/linux/err.h b/include/linux/err.h
index 221fcfb676c4..8c37be0620ab 100644
--- a/include/linux/err.h
+++ b/include/linux/err.h
@@ -1,13 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _LINUX_ERR_H
 #define _LINUX_ERR_H
 
 #include <linux/compiler.h>
+#include <linux/types.h>
 
 #include <asm/errno.h>
 
 /*
  * Kernel pointers have redundant information, so we can use a
- * scheme where we can return either an error code or a dentry
+ * scheme where we can return either an error code or a normal
  * pointer with the same return value.
  *
  * This should be a per-architecture thing, to allow different
@@ -17,26 +19,77 @@
 
 #ifndef __ASSEMBLY__
 
-#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)
+/**
+ * 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;
 }
 
+/**
+ * INIT_ERR_PTR - Init a const error pointer.
+ * @error: A negative error code.
+ *
+ * Like ERR_PTR(), but usable to initialize static variables.
+ */
+#define INIT_ERR_PTR(error) ((void *)(error))
+
+/* Return the pointer in the percpu address space. */
+#define ERR_PTR_PCPU(error) ((void __percpu *)(unsigned long)ERR_PTR(error))
+
+/* Cast an error pointer to __iomem. */
+#define IOMEM_ERR_PTR(error) (__force void __iomem *)ERR_PTR(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;
 }
 
-static inline long __must_check IS_ERR(__force const void *ptr)
+/* Read an error pointer from the percpu address space. */
+#define PTR_ERR_PCPU(ptr) (PTR_ERR((const void *)(__force const unsigned 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);
 }
 
-static inline long __must_check IS_ERR_OR_NULL(__force const void *ptr)
+/* Read an error pointer from the percpu address space. */
+#define IS_ERR_PCPU(ptr) (IS_ERR((const void *)(__force const 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 !ptr || IS_ERR_VALUE((unsigned long)ptr);
+	return unlikely(!ptr) || IS_ERR_VALUE((unsigned long)ptr);
 }
 
 /**
@@ -52,7 +105,24 @@ static inline void * __must_check ERR_CAST(__force const void *ptr)
 	return (void *) ptr;
 }
 
-static inline int __must_check PTR_RET(__force const 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))
 		return PTR_ERR(ptr);