#ifndef _LINUX_ERR_H
#define _LINUX_ERR_H

#include <linux/compiler.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
 * pointer with the same return value.
 *
 * This should be a per-architecture thing, to allow different
 * error and pointer decisions.
 */
#define MAX_ERRNO	4095

#ifndef __ASSEMBLY__

#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)

static inline void *ERR_PTR(long error)
{
	return (void *) error;
}

static inline long PTR_ERR(const void *ptr)
{
	return (long) ptr;
}

static inline long IS_ERR(const void *ptr)
{
	return IS_ERR_VALUE((unsigned long)ptr);
}

#endif

#endif /* _LINUX_ERR_H */

#ifndef _LINUX_ERR_H
#define _LINUX_ERR_H

#include <linux/compiler.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
 * pointer with the same return value.
 *
 * This should be a per-architecture thing, to allow different
 * error and pointer decisions.
 */
#define MAX_ERRNO	4095

#ifndef __ASSEMBLY__

#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)

static inline void *ERR_PTR(long error)
{
	return (void *) error;
}

static inline long PTR_ERR(const void *ptr)
{
	return (long) ptr;
}

static inline long IS_ERR(const void *ptr)
{
	return IS_ERR_VALUE((unsigned long)ptr);
}

/**
 * ERR_CAST - Explicitly cast an error-valued pointer to another pointer type
 * @ptr: The pointer to cast.
 *
 * Explicitly cast an error-valued pointer to another pointer type in such a
 * way as to make it clear that's what's going on.
 */
static inline void *ERR_CAST(const void *ptr)
{
	/* cast away the const */
	return (void *) ptr;
}

#endif

#endif /* _LINUX_ERR_H */

Add an ERR_CAST() function to complement ERR_PTR and co.
Add an ERR_CAST() function to complement ERR_PTR and co.

Add an ERR_CAST() function to complement ERR_PTR and co.  for the purposes
of casting an error entyped as one pointer type to an error of another
pointer type whilst making it explicit as to what is going on.

This provides a replacement for the ERR_PTR(PTR_ERR(p)) construct.

Signed-off-by: David Howells <ebac1d06c1688626821bb0e574a037a7a5354e49@redhat.com>
Signed-off-by: Andrew Morton <5c1e68b099950c134891f0b6e179498a8ebe9cf9@linux-foundation.org>
Signed-off-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>
