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/* SPDX-License-Identifier: GPL-2.0+ */
#ifndef _LINUX_XARRAY_H
#define _LINUX_XARRAY_H
/*
* eXtensible Arrays
* Copyright (c) 2017 Microsoft Corporation
* Author: Matthew Wilcox <willy@infradead.org>
*
* See Documentation/core-api/xarray.rst for how to use the XArray.
*/
#include <linux/bug.h>
#include <linux/spinlock.h>
#include <linux/types.h>
/*
* The bottom two bits of the entry determine how the XArray interprets
* the contents:
*
* 00: Pointer entry
* 10: Internal entry
* x1: Value entry or tagged pointer
*
* Attempting to store internal entries in the XArray is a bug.
*/
#define BITS_PER_XA_VALUE (BITS_PER_LONG - 1)
/**
* xa_mk_value() - Create an XArray entry from an integer.
* @v: Value to store in XArray.
*
* Context: Any context.
* Return: An entry suitable for storing in the XArray.
*/
static inline void *xa_mk_value(unsigned long v)
{
WARN_ON((long)v < 0);
return (void *)((v << 1) | 1);
}
/**
* xa_to_value() - Get value stored in an XArray entry.
* @entry: XArray entry.
*
* Context: Any context.
* Return: The value stored in the XArray entry.
*/
static inline unsigned long xa_to_value(const void *entry)
{
return (unsigned long)entry >> 1;
}
/**
* xa_is_value() - Determine if an entry is a value.
* @entry: XArray entry.
*
* Context: Any context.
* Return: True if the entry is a value, false if it is a pointer.
*/
static inline bool xa_is_value(const void *entry)
{
return (unsigned long)entry & 1;
}
/**
* xa_tag_pointer() - Create an XArray entry for a tagged pointer.
* @p: Plain pointer.
* @tag: Tag value (0, 1 or 3).
*
* If the user of the XArray prefers, they can tag their pointers instead
* of storing value entries. Three tags are available (0, 1 and 3).
* These are distinct from the xa_mark_t as they are not replicated up
* through the array and cannot be searched for.
*
* Context: Any context.
* Return: An XArray entry.
*/
static inline void *xa_tag_pointer(void *p, unsigned long tag)
{
return (void *)((unsigned long)p | tag);
}
/**
* xa_untag_pointer() - Turn an XArray entry into a plain pointer.
* @entry: XArray entry.
*
* If you have stored a tagged pointer in the XArray, call this function
* to get the untagged version of the pointer.
*
* Context: Any context.
* Return: A pointer.
*/
static inline void *xa_untag_pointer(void *entry)
{
return (void *)((unsigned long)entry & ~3UL);
}
/**
* xa_pointer_tag() - Get the tag stored in an XArray entry.
* @entry: XArray entry.
*
* If you have stored a tagged pointer in the XArray, call this function
* to get the tag of that pointer.
*
* Context: Any context.
* Return: A tag.
*/
static inline unsigned int xa_pointer_tag(void *entry)
{
return (unsigned long)entry & 3UL;
}
#define xa_trylock(xa) spin_trylock(&(xa)->xa_lock)
#define xa_lock(xa) spin_lock(&(xa)->xa_lock)
#define xa_unlock(xa) spin_unlock(&(xa)->xa_lock)
#define xa_lock_bh(xa) spin_lock_bh(&(xa)->xa_lock)
#define xa_unlock_bh(xa) spin_unlock_bh(&(xa)->xa_lock)
#define xa_lock_irq(xa) spin_lock_irq(&(xa)->xa_lock)
#define xa_unlock_irq(xa) spin_unlock_irq(&(xa)->xa_lock)
#define xa_lock_irqsave(xa, flags) \
spin_lock_irqsave(&(xa)->xa_lock, flags)
#define xa_unlock_irqrestore(xa, flags) \
spin_unlock_irqrestore(&(xa)->xa_lock, flags)
#endif /* _LINUX_XARRAY_H */
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