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