err.h

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#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 * __must_check ERR_PTR(long error)
{
    return (void *) error;
}

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

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

static inline long __must_check IS_ERR_OR_NULL(const void *ptr)
{
    return !ptr || IS_ERR_VALUE((unsigned long)ptr);
}

static inline void * __must_check ERR_CAST(const void *ptr)
{
    /* cast away the const */
    return (void *) ptr;
}

static inline int __must_check PTR_RET(const void *ptr)
{
    if (IS_ERR(ptr))
        return PTR_ERR(ptr);
    else
        return 0;
}

#endif

#endif /* _LINUX_ERR_H */