![Matthew Wilcox](/assets/img/avatar_default.png)
Jason feels this is clearer, and it saves a function and an exported symbol. Suggested-by: Jason Gunthorpe <jgg@ziepe.ca> Signed-off-by: Matthew Wilcox <willy@infradead.org>
1750 lines
54 KiB
C
1750 lines
54 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/compiler.h>
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#include <linux/gfp.h>
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#include <linux/kconfig.h>
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#include <linux/kernel.h>
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#include <linux/rcupdate.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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* Most internal entries are pointers to the next node in the tree.
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* The following internal entries have a special meaning:
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*
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* 0-62: Sibling entries
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* 256: Zero entry
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* 257: Retry entry
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*
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* Errors are also represented as internal entries, but use the negative
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* space (-4094 to -2). They're never stored in the slots array; only
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* returned by the normal API.
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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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/*
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* xa_mk_internal() - Create an internal entry.
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* @v: Value to turn into an internal entry.
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*
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* Internal entries are used for a number of purposes. Entries 0-255 are
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* used for sibling entries (only 0-62 are used by the current code). 256
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* is used for the retry entry. 257 is used for the reserved / zero entry.
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* Negative internal entries are used to represent errnos. Node pointers
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* are also tagged as internal entries in some situations.
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*
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* Context: Any context.
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* Return: An XArray internal entry corresponding to this value.
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*/
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static inline void *xa_mk_internal(unsigned long v)
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{
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return (void *)((v << 2) | 2);
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}
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/*
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* xa_to_internal() - Extract the value from an internal 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 which was stored in the internal entry.
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*/
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static inline unsigned long xa_to_internal(const void *entry)
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{
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return (unsigned long)entry >> 2;
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}
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/*
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* xa_is_internal() - Is the entry an internal entry?
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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 an internal entry.
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*/
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static inline bool xa_is_internal(const void *entry)
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{
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return ((unsigned long)entry & 3) == 2;
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}
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#define XA_ZERO_ENTRY xa_mk_internal(257)
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/**
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* xa_is_zero() - Is the entry a zero entry?
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* @entry: Entry retrieved from the XArray
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*
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* The normal API will return NULL as the contents of a slot containing
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* a zero entry. You can only see zero entries by using the advanced API.
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*
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* Return: %true if the entry is a zero entry.
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*/
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static inline bool xa_is_zero(const void *entry)
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{
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return unlikely(entry == XA_ZERO_ENTRY);
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}
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/**
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* xa_is_err() - Report whether an XArray operation returned an error
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* @entry: Result from calling an XArray function
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*
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* If an XArray operation cannot complete an operation, it will return
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* a special value indicating an error. This function tells you
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* whether an error occurred; xa_err() tells you which error occurred.
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*
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* Context: Any context.
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* Return: %true if the entry indicates an error.
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*/
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static inline bool xa_is_err(const void *entry)
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{
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return unlikely(xa_is_internal(entry) &&
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entry >= xa_mk_internal(-MAX_ERRNO));
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}
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/**
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* xa_err() - Turn an XArray result into an errno.
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* @entry: Result from calling an XArray function.
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*
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* If an XArray operation cannot complete an operation, it will return
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* a special pointer value which encodes an errno. This function extracts
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* the errno from the pointer value, or returns 0 if the pointer does not
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* represent an errno.
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*
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* Context: Any context.
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* Return: A negative errno or 0.
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*/
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static inline int xa_err(void *entry)
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{
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/* xa_to_internal() would not do sign extension. */
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if (xa_is_err(entry))
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return (long)entry >> 2;
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return 0;
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}
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/**
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* struct xa_limit - Represents a range of IDs.
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* @min: The lowest ID to allocate (inclusive).
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* @max: The maximum ID to allocate (inclusive).
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*
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* This structure is used either directly or via the XA_LIMIT() macro
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* to communicate the range of IDs that are valid for allocation.
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* Two common ranges are predefined for you:
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* * xa_limit_32b - [0 - UINT_MAX]
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* * xa_limit_31b - [0 - INT_MAX]
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*/
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struct xa_limit {
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u32 max;
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u32 min;
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};
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#define XA_LIMIT(_min, _max) (struct xa_limit) { .min = _min, .max = _max }
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#define xa_limit_32b XA_LIMIT(0, UINT_MAX)
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#define xa_limit_31b XA_LIMIT(0, INT_MAX)
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typedef unsigned __bitwise xa_mark_t;
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#define XA_MARK_0 ((__force xa_mark_t)0U)
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#define XA_MARK_1 ((__force xa_mark_t)1U)
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#define XA_MARK_2 ((__force xa_mark_t)2U)
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#define XA_PRESENT ((__force xa_mark_t)8U)
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#define XA_MARK_MAX XA_MARK_2
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#define XA_FREE_MARK XA_MARK_0
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enum xa_lock_type {
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XA_LOCK_IRQ = 1,
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XA_LOCK_BH = 2,
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};
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/*
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* Values for xa_flags. The radix tree stores its GFP flags in the xa_flags,
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* and we remain compatible with that.
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*/
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#define XA_FLAGS_LOCK_IRQ ((__force gfp_t)XA_LOCK_IRQ)
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#define XA_FLAGS_LOCK_BH ((__force gfp_t)XA_LOCK_BH)
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#define XA_FLAGS_TRACK_FREE ((__force gfp_t)4U)
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#define XA_FLAGS_ZERO_BUSY ((__force gfp_t)8U)
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#define XA_FLAGS_ALLOC_WRAPPED ((__force gfp_t)16U)
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#define XA_FLAGS_MARK(mark) ((__force gfp_t)((1U << __GFP_BITS_SHIFT) << \
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(__force unsigned)(mark)))
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/* ALLOC is for a normal 0-based alloc. ALLOC1 is for an 1-based alloc */
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#define XA_FLAGS_ALLOC (XA_FLAGS_TRACK_FREE | XA_FLAGS_MARK(XA_FREE_MARK))
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#define XA_FLAGS_ALLOC1 (XA_FLAGS_TRACK_FREE | XA_FLAGS_ZERO_BUSY)
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/**
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* struct xarray - The anchor of the XArray.
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* @xa_lock: Lock that protects the contents of the XArray.
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*
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* To use the xarray, define it statically or embed it in your data structure.
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* It is a very small data structure, so it does not usually make sense to
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* allocate it separately and keep a pointer to it in your data structure.
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*
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* You may use the xa_lock to protect your own data structures as well.
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*/
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/*
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* If all of the entries in the array are NULL, @xa_head is a NULL pointer.
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* If the only non-NULL entry in the array is at index 0, @xa_head is that
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* entry. If any other entry in the array is non-NULL, @xa_head points
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* to an @xa_node.
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*/
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struct xarray {
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spinlock_t xa_lock;
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/* private: The rest of the data structure is not to be used directly. */
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gfp_t xa_flags;
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void __rcu * xa_head;
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};
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#define XARRAY_INIT(name, flags) { \
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.xa_lock = __SPIN_LOCK_UNLOCKED(name.xa_lock), \
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.xa_flags = flags, \
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.xa_head = NULL, \
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}
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/**
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* DEFINE_XARRAY_FLAGS() - Define an XArray with custom flags.
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* @name: A string that names your XArray.
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* @flags: XA_FLAG values.
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*
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* This is intended for file scope definitions of XArrays. It declares
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* and initialises an empty XArray with the chosen name and flags. It is
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* equivalent to calling xa_init_flags() on the array, but it does the
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* initialisation at compiletime instead of runtime.
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*/
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#define DEFINE_XARRAY_FLAGS(name, flags) \
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struct xarray name = XARRAY_INIT(name, flags)
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/**
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* DEFINE_XARRAY() - Define an XArray.
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* @name: A string that names your XArray.
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*
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* This is intended for file scope definitions of XArrays. It declares
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* and initialises an empty XArray with the chosen name. It is equivalent
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* to calling xa_init() on the array, but it does the initialisation at
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* compiletime instead of runtime.
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*/
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#define DEFINE_XARRAY(name) DEFINE_XARRAY_FLAGS(name, 0)
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/**
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* DEFINE_XARRAY_ALLOC() - Define an XArray which allocates IDs starting at 0.
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* @name: A string that names your XArray.
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*
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* This is intended for file scope definitions of allocating XArrays.
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* See also DEFINE_XARRAY().
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*/
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#define DEFINE_XARRAY_ALLOC(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC)
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/**
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* DEFINE_XARRAY_ALLOC1() - Define an XArray which allocates IDs starting at 1.
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* @name: A string that names your XArray.
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*
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* This is intended for file scope definitions of allocating XArrays.
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* See also DEFINE_XARRAY().
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*/
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#define DEFINE_XARRAY_ALLOC1(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC1)
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void *xa_load(struct xarray *, unsigned long index);
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void *xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
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void *xa_erase(struct xarray *, unsigned long index);
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void *xa_store_range(struct xarray *, unsigned long first, unsigned long last,
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void *entry, gfp_t);
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bool xa_get_mark(struct xarray *, unsigned long index, xa_mark_t);
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void xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
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void xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
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void *xa_find(struct xarray *xa, unsigned long *index,
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unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
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void *xa_find_after(struct xarray *xa, unsigned long *index,
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unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
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unsigned int xa_extract(struct xarray *, void **dst, unsigned long start,
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unsigned long max, unsigned int n, xa_mark_t);
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void xa_destroy(struct xarray *);
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/**
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* xa_init_flags() - Initialise an empty XArray with flags.
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* @xa: XArray.
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* @flags: XA_FLAG values.
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*
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* If you need to initialise an XArray with special flags (eg you need
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* to take the lock from interrupt context), use this function instead
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* of xa_init().
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*
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* Context: Any context.
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*/
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static inline void xa_init_flags(struct xarray *xa, gfp_t flags)
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{
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spin_lock_init(&xa->xa_lock);
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xa->xa_flags = flags;
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xa->xa_head = NULL;
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}
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/**
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* xa_init() - Initialise an empty XArray.
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* @xa: XArray.
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*
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* An empty XArray is full of NULL entries.
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*
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* Context: Any context.
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*/
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static inline void xa_init(struct xarray *xa)
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{
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xa_init_flags(xa, 0);
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}
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/**
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* xa_empty() - Determine if an array has any present entries.
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* @xa: XArray.
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*
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* Context: Any context.
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* Return: %true if the array contains only NULL pointers.
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*/
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static inline bool xa_empty(const struct xarray *xa)
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{
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return xa->xa_head == NULL;
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}
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/**
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* xa_marked() - Inquire whether any entry in this array has a mark set
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* @xa: Array
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* @mark: Mark value
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*
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* Context: Any context.
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* Return: %true if any entry has this mark set.
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*/
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static inline bool xa_marked(const struct xarray *xa, xa_mark_t mark)
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{
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return xa->xa_flags & XA_FLAGS_MARK(mark);
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}
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/**
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* xa_for_each_start() - Iterate over a portion of an XArray.
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* @xa: XArray.
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* @index: Index of @entry.
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* @entry: Entry retrieved from array.
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* @start: First index to retrieve from array.
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*
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* During the iteration, @entry will have the value of the entry stored
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* in @xa at @index. You may modify @index during the iteration if you
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* want to skip or reprocess indices. It is safe to modify the array
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* during the iteration. At the end of the iteration, @entry will be set
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* to NULL and @index will have a value less than or equal to max.
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*
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* xa_for_each_start() is O(n.log(n)) while xas_for_each() is O(n). You have
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* to handle your own locking with xas_for_each(), and if you have to unlock
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* after each iteration, it will also end up being O(n.log(n)).
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* xa_for_each_start() will spin if it hits a retry entry; if you intend to
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* see retry entries, you should use the xas_for_each() iterator instead.
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* The xas_for_each() iterator will expand into more inline code than
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* xa_for_each_start().
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*
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* Context: Any context. Takes and releases the RCU lock.
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*/
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#define xa_for_each_start(xa, index, entry, start) \
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for (index = start, \
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entry = xa_find(xa, &index, ULONG_MAX, XA_PRESENT); \
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entry; \
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entry = xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT))
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/**
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* xa_for_each() - Iterate over present entries in an XArray.
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* @xa: XArray.
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* @index: Index of @entry.
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* @entry: Entry retrieved from array.
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*
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* During the iteration, @entry will have the value of the entry stored
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* in @xa at @index. You may modify @index during the iteration if you want
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* to skip or reprocess indices. It is safe to modify the array during the
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* iteration. At the end of the iteration, @entry will be set to NULL and
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* @index will have a value less than or equal to max.
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*
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* xa_for_each() is O(n.log(n)) while xas_for_each() is O(n). You have
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* to handle your own locking with xas_for_each(), and if you have to unlock
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* after each iteration, it will also end up being O(n.log(n)). xa_for_each()
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* will spin if it hits a retry entry; if you intend to see retry entries,
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* you should use the xas_for_each() iterator instead. The xas_for_each()
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* iterator will expand into more inline code than xa_for_each().
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*
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* Context: Any context. Takes and releases the RCU lock.
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*/
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#define xa_for_each(xa, index, entry) \
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xa_for_each_start(xa, index, entry, 0)
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/**
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* xa_for_each_marked() - Iterate over marked entries in an XArray.
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* @xa: XArray.
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* @index: Index of @entry.
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* @entry: Entry retrieved from array.
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* @filter: Selection criterion.
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*
|
|
* During the iteration, @entry will have the value of the entry stored
|
|
* in @xa at @index. The iteration will skip all entries in the array
|
|
* which do not match @filter. You may modify @index during the iteration
|
|
* if you want to skip or reprocess indices. It is safe to modify the array
|
|
* during the iteration. At the end of the iteration, @entry will be set to
|
|
* NULL and @index will have a value less than or equal to max.
|
|
*
|
|
* xa_for_each_marked() is O(n.log(n)) while xas_for_each_marked() is O(n).
|
|
* You have to handle your own locking with xas_for_each(), and if you have
|
|
* to unlock after each iteration, it will also end up being O(n.log(n)).
|
|
* xa_for_each_marked() will spin if it hits a retry entry; if you intend to
|
|
* see retry entries, you should use the xas_for_each_marked() iterator
|
|
* instead. The xas_for_each_marked() iterator will expand into more inline
|
|
* code than xa_for_each_marked().
|
|
*
|
|
* Context: Any context. Takes and releases the RCU lock.
|
|
*/
|
|
#define xa_for_each_marked(xa, index, entry, filter) \
|
|
for (index = 0, entry = xa_find(xa, &index, ULONG_MAX, filter); \
|
|
entry; entry = xa_find_after(xa, &index, ULONG_MAX, filter))
|
|
|
|
#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)
|
|
|
|
/*
|
|
* Versions of the normal API which require the caller to hold the
|
|
* xa_lock. If the GFP flags allow it, they will drop the lock to
|
|
* allocate memory, then reacquire it afterwards. These functions
|
|
* may also re-enable interrupts if the XArray flags indicate the
|
|
* locking should be interrupt safe.
|
|
*/
|
|
void *__xa_erase(struct xarray *, unsigned long index);
|
|
void *__xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
|
|
void *__xa_cmpxchg(struct xarray *, unsigned long index, void *old,
|
|
void *entry, gfp_t);
|
|
int __must_check __xa_insert(struct xarray *, unsigned long index,
|
|
void *entry, gfp_t);
|
|
int __must_check __xa_alloc(struct xarray *, u32 *id, void *entry,
|
|
struct xa_limit, gfp_t);
|
|
int __must_check __xa_alloc_cyclic(struct xarray *, u32 *id, void *entry,
|
|
struct xa_limit, u32 *next, gfp_t);
|
|
void __xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
|
|
void __xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
|
|
|
|
/**
|
|
* xa_store_bh() - Store this entry in the XArray.
|
|
* @xa: XArray.
|
|
* @index: Index into array.
|
|
* @entry: New entry.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* This function is like calling xa_store() except it disables softirqs
|
|
* while holding the array lock.
|
|
*
|
|
* Context: Any context. Takes and releases the xa_lock while
|
|
* disabling softirqs.
|
|
* Return: The entry which used to be at this index.
|
|
*/
|
|
static inline void *xa_store_bh(struct xarray *xa, unsigned long index,
|
|
void *entry, gfp_t gfp)
|
|
{
|
|
void *curr;
|
|
|
|
xa_lock_bh(xa);
|
|
curr = __xa_store(xa, index, entry, gfp);
|
|
xa_unlock_bh(xa);
|
|
|
|
return curr;
|
|
}
|
|
|
|
/**
|
|
* xa_store_irq() - Store this entry in the XArray.
|
|
* @xa: XArray.
|
|
* @index: Index into array.
|
|
* @entry: New entry.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* This function is like calling xa_store() except it disables interrupts
|
|
* while holding the array lock.
|
|
*
|
|
* Context: Process context. Takes and releases the xa_lock while
|
|
* disabling interrupts.
|
|
* Return: The entry which used to be at this index.
|
|
*/
|
|
static inline void *xa_store_irq(struct xarray *xa, unsigned long index,
|
|
void *entry, gfp_t gfp)
|
|
{
|
|
void *curr;
|
|
|
|
xa_lock_irq(xa);
|
|
curr = __xa_store(xa, index, entry, gfp);
|
|
xa_unlock_irq(xa);
|
|
|
|
return curr;
|
|
}
|
|
|
|
/**
|
|
* xa_erase_bh() - Erase this entry from the XArray.
|
|
* @xa: XArray.
|
|
* @index: Index of entry.
|
|
*
|
|
* After this function returns, loading from @index will return %NULL.
|
|
* If the index is part of a multi-index entry, all indices will be erased
|
|
* and none of the entries will be part of a multi-index entry.
|
|
*
|
|
* Context: Any context. Takes and releases the xa_lock while
|
|
* disabling softirqs.
|
|
* Return: The entry which used to be at this index.
|
|
*/
|
|
static inline void *xa_erase_bh(struct xarray *xa, unsigned long index)
|
|
{
|
|
void *entry;
|
|
|
|
xa_lock_bh(xa);
|
|
entry = __xa_erase(xa, index);
|
|
xa_unlock_bh(xa);
|
|
|
|
return entry;
|
|
}
|
|
|
|
/**
|
|
* xa_erase_irq() - Erase this entry from the XArray.
|
|
* @xa: XArray.
|
|
* @index: Index of entry.
|
|
*
|
|
* After this function returns, loading from @index will return %NULL.
|
|
* If the index is part of a multi-index entry, all indices will be erased
|
|
* and none of the entries will be part of a multi-index entry.
|
|
*
|
|
* Context: Process context. Takes and releases the xa_lock while
|
|
* disabling interrupts.
|
|
* Return: The entry which used to be at this index.
|
|
*/
|
|
static inline void *xa_erase_irq(struct xarray *xa, unsigned long index)
|
|
{
|
|
void *entry;
|
|
|
|
xa_lock_irq(xa);
|
|
entry = __xa_erase(xa, index);
|
|
xa_unlock_irq(xa);
|
|
|
|
return entry;
|
|
}
|
|
|
|
/**
|
|
* xa_cmpxchg() - Conditionally replace an entry in the XArray.
|
|
* @xa: XArray.
|
|
* @index: Index into array.
|
|
* @old: Old value to test against.
|
|
* @entry: New value to place in array.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* If the entry at @index is the same as @old, replace it with @entry.
|
|
* If the return value is equal to @old, then the exchange was successful.
|
|
*
|
|
* Context: Any context. Takes and releases the xa_lock. May sleep
|
|
* if the @gfp flags permit.
|
|
* Return: The old value at this index or xa_err() if an error happened.
|
|
*/
|
|
static inline void *xa_cmpxchg(struct xarray *xa, unsigned long index,
|
|
void *old, void *entry, gfp_t gfp)
|
|
{
|
|
void *curr;
|
|
|
|
xa_lock(xa);
|
|
curr = __xa_cmpxchg(xa, index, old, entry, gfp);
|
|
xa_unlock(xa);
|
|
|
|
return curr;
|
|
}
|
|
|
|
/**
|
|
* xa_cmpxchg_bh() - Conditionally replace an entry in the XArray.
|
|
* @xa: XArray.
|
|
* @index: Index into array.
|
|
* @old: Old value to test against.
|
|
* @entry: New value to place in array.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* This function is like calling xa_cmpxchg() except it disables softirqs
|
|
* while holding the array lock.
|
|
*
|
|
* Context: Any context. Takes and releases the xa_lock while
|
|
* disabling softirqs. May sleep if the @gfp flags permit.
|
|
* Return: The old value at this index or xa_err() if an error happened.
|
|
*/
|
|
static inline void *xa_cmpxchg_bh(struct xarray *xa, unsigned long index,
|
|
void *old, void *entry, gfp_t gfp)
|
|
{
|
|
void *curr;
|
|
|
|
xa_lock_bh(xa);
|
|
curr = __xa_cmpxchg(xa, index, old, entry, gfp);
|
|
xa_unlock_bh(xa);
|
|
|
|
return curr;
|
|
}
|
|
|
|
/**
|
|
* xa_cmpxchg_irq() - Conditionally replace an entry in the XArray.
|
|
* @xa: XArray.
|
|
* @index: Index into array.
|
|
* @old: Old value to test against.
|
|
* @entry: New value to place in array.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* This function is like calling xa_cmpxchg() except it disables interrupts
|
|
* while holding the array lock.
|
|
*
|
|
* Context: Process context. Takes and releases the xa_lock while
|
|
* disabling interrupts. May sleep if the @gfp flags permit.
|
|
* Return: The old value at this index or xa_err() if an error happened.
|
|
*/
|
|
static inline void *xa_cmpxchg_irq(struct xarray *xa, unsigned long index,
|
|
void *old, void *entry, gfp_t gfp)
|
|
{
|
|
void *curr;
|
|
|
|
xa_lock_irq(xa);
|
|
curr = __xa_cmpxchg(xa, index, old, entry, gfp);
|
|
xa_unlock_irq(xa);
|
|
|
|
return curr;
|
|
}
|
|
|
|
/**
|
|
* xa_insert() - Store this entry in the XArray unless another entry is
|
|
* already present.
|
|
* @xa: XArray.
|
|
* @index: Index into array.
|
|
* @entry: New entry.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* Inserting a NULL entry will store a reserved entry (like xa_reserve())
|
|
* if no entry is present. Inserting will fail if a reserved entry is
|
|
* present, even though loading from this index will return NULL.
|
|
*
|
|
* Context: Any context. Takes and releases the xa_lock. May sleep if
|
|
* the @gfp flags permit.
|
|
* Return: 0 if the store succeeded. -EBUSY if another entry was present.
|
|
* -ENOMEM if memory could not be allocated.
|
|
*/
|
|
static inline int __must_check xa_insert(struct xarray *xa,
|
|
unsigned long index, void *entry, gfp_t gfp)
|
|
{
|
|
int err;
|
|
|
|
xa_lock(xa);
|
|
err = __xa_insert(xa, index, entry, gfp);
|
|
xa_unlock(xa);
|
|
|
|
return err;
|
|
}
|
|
|
|
/**
|
|
* xa_insert_bh() - Store this entry in the XArray unless another entry is
|
|
* already present.
|
|
* @xa: XArray.
|
|
* @index: Index into array.
|
|
* @entry: New entry.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* Inserting a NULL entry will store a reserved entry (like xa_reserve())
|
|
* if no entry is present. Inserting will fail if a reserved entry is
|
|
* present, even though loading from this index will return NULL.
|
|
*
|
|
* Context: Any context. Takes and releases the xa_lock while
|
|
* disabling softirqs. May sleep if the @gfp flags permit.
|
|
* Return: 0 if the store succeeded. -EBUSY if another entry was present.
|
|
* -ENOMEM if memory could not be allocated.
|
|
*/
|
|
static inline int __must_check xa_insert_bh(struct xarray *xa,
|
|
unsigned long index, void *entry, gfp_t gfp)
|
|
{
|
|
int err;
|
|
|
|
xa_lock_bh(xa);
|
|
err = __xa_insert(xa, index, entry, gfp);
|
|
xa_unlock_bh(xa);
|
|
|
|
return err;
|
|
}
|
|
|
|
/**
|
|
* xa_insert_irq() - Store this entry in the XArray unless another entry is
|
|
* already present.
|
|
* @xa: XArray.
|
|
* @index: Index into array.
|
|
* @entry: New entry.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* Inserting a NULL entry will store a reserved entry (like xa_reserve())
|
|
* if no entry is present. Inserting will fail if a reserved entry is
|
|
* present, even though loading from this index will return NULL.
|
|
*
|
|
* Context: Process context. Takes and releases the xa_lock while
|
|
* disabling interrupts. May sleep if the @gfp flags permit.
|
|
* Return: 0 if the store succeeded. -EBUSY if another entry was present.
|
|
* -ENOMEM if memory could not be allocated.
|
|
*/
|
|
static inline int __must_check xa_insert_irq(struct xarray *xa,
|
|
unsigned long index, void *entry, gfp_t gfp)
|
|
{
|
|
int err;
|
|
|
|
xa_lock_irq(xa);
|
|
err = __xa_insert(xa, index, entry, gfp);
|
|
xa_unlock_irq(xa);
|
|
|
|
return err;
|
|
}
|
|
|
|
/**
|
|
* xa_alloc() - Find somewhere to store this entry in the XArray.
|
|
* @xa: XArray.
|
|
* @id: Pointer to ID.
|
|
* @entry: New entry.
|
|
* @limit: Range of ID to allocate.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* Finds an empty entry in @xa between @limit.min and @limit.max,
|
|
* stores the index into the @id pointer, then stores the entry at
|
|
* that index. A concurrent lookup will not see an uninitialised @id.
|
|
*
|
|
* Context: Any context. Takes and releases the xa_lock. May sleep if
|
|
* the @gfp flags permit.
|
|
* Return: 0 on success, -ENOMEM if memory could not be allocated or
|
|
* -EBUSY if there are no free entries in @limit.
|
|
*/
|
|
static inline __must_check int xa_alloc(struct xarray *xa, u32 *id,
|
|
void *entry, struct xa_limit limit, gfp_t gfp)
|
|
{
|
|
int err;
|
|
|
|
xa_lock(xa);
|
|
err = __xa_alloc(xa, id, entry, limit, gfp);
|
|
xa_unlock(xa);
|
|
|
|
return err;
|
|
}
|
|
|
|
/**
|
|
* xa_alloc_bh() - Find somewhere to store this entry in the XArray.
|
|
* @xa: XArray.
|
|
* @id: Pointer to ID.
|
|
* @entry: New entry.
|
|
* @limit: Range of ID to allocate.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* Finds an empty entry in @xa between @limit.min and @limit.max,
|
|
* stores the index into the @id pointer, then stores the entry at
|
|
* that index. A concurrent lookup will not see an uninitialised @id.
|
|
*
|
|
* Context: Any context. Takes and releases the xa_lock while
|
|
* disabling softirqs. May sleep if the @gfp flags permit.
|
|
* Return: 0 on success, -ENOMEM if memory could not be allocated or
|
|
* -EBUSY if there are no free entries in @limit.
|
|
*/
|
|
static inline int __must_check xa_alloc_bh(struct xarray *xa, u32 *id,
|
|
void *entry, struct xa_limit limit, gfp_t gfp)
|
|
{
|
|
int err;
|
|
|
|
xa_lock_bh(xa);
|
|
err = __xa_alloc(xa, id, entry, limit, gfp);
|
|
xa_unlock_bh(xa);
|
|
|
|
return err;
|
|
}
|
|
|
|
/**
|
|
* xa_alloc_irq() - Find somewhere to store this entry in the XArray.
|
|
* @xa: XArray.
|
|
* @id: Pointer to ID.
|
|
* @entry: New entry.
|
|
* @limit: Range of ID to allocate.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* Finds an empty entry in @xa between @limit.min and @limit.max,
|
|
* stores the index into the @id pointer, then stores the entry at
|
|
* that index. A concurrent lookup will not see an uninitialised @id.
|
|
*
|
|
* Context: Process context. Takes and releases the xa_lock while
|
|
* disabling interrupts. May sleep if the @gfp flags permit.
|
|
* Return: 0 on success, -ENOMEM if memory could not be allocated or
|
|
* -EBUSY if there are no free entries in @limit.
|
|
*/
|
|
static inline int __must_check xa_alloc_irq(struct xarray *xa, u32 *id,
|
|
void *entry, struct xa_limit limit, gfp_t gfp)
|
|
{
|
|
int err;
|
|
|
|
xa_lock_irq(xa);
|
|
err = __xa_alloc(xa, id, entry, limit, gfp);
|
|
xa_unlock_irq(xa);
|
|
|
|
return err;
|
|
}
|
|
|
|
/**
|
|
* xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
|
|
* @xa: XArray.
|
|
* @id: Pointer to ID.
|
|
* @entry: New entry.
|
|
* @limit: Range of allocated ID.
|
|
* @next: Pointer to next ID to allocate.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* Finds an empty entry in @xa between @limit.min and @limit.max,
|
|
* stores the index into the @id pointer, then stores the entry at
|
|
* that index. A concurrent lookup will not see an uninitialised @id.
|
|
* The search for an empty entry will start at @next and will wrap
|
|
* around if necessary.
|
|
*
|
|
* Context: Any context. Takes and releases the xa_lock. May sleep if
|
|
* the @gfp flags permit.
|
|
* Return: 0 if the allocation succeeded without wrapping. 1 if the
|
|
* allocation succeeded after wrapping, -ENOMEM if memory could not be
|
|
* allocated or -EBUSY if there are no free entries in @limit.
|
|
*/
|
|
static inline int xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
|
|
struct xa_limit limit, u32 *next, gfp_t gfp)
|
|
{
|
|
int err;
|
|
|
|
xa_lock(xa);
|
|
err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
|
|
xa_unlock(xa);
|
|
|
|
return err;
|
|
}
|
|
|
|
/**
|
|
* xa_alloc_cyclic_bh() - Find somewhere to store this entry in the XArray.
|
|
* @xa: XArray.
|
|
* @id: Pointer to ID.
|
|
* @entry: New entry.
|
|
* @limit: Range of allocated ID.
|
|
* @next: Pointer to next ID to allocate.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* Finds an empty entry in @xa between @limit.min and @limit.max,
|
|
* stores the index into the @id pointer, then stores the entry at
|
|
* that index. A concurrent lookup will not see an uninitialised @id.
|
|
* The search for an empty entry will start at @next and will wrap
|
|
* around if necessary.
|
|
*
|
|
* Context: Any context. Takes and releases the xa_lock while
|
|
* disabling softirqs. May sleep if the @gfp flags permit.
|
|
* Return: 0 if the allocation succeeded without wrapping. 1 if the
|
|
* allocation succeeded after wrapping, -ENOMEM if memory could not be
|
|
* allocated or -EBUSY if there are no free entries in @limit.
|
|
*/
|
|
static inline int xa_alloc_cyclic_bh(struct xarray *xa, u32 *id, void *entry,
|
|
struct xa_limit limit, u32 *next, gfp_t gfp)
|
|
{
|
|
int err;
|
|
|
|
xa_lock_bh(xa);
|
|
err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
|
|
xa_unlock_bh(xa);
|
|
|
|
return err;
|
|
}
|
|
|
|
/**
|
|
* xa_alloc_cyclic_irq() - Find somewhere to store this entry in the XArray.
|
|
* @xa: XArray.
|
|
* @id: Pointer to ID.
|
|
* @entry: New entry.
|
|
* @limit: Range of allocated ID.
|
|
* @next: Pointer to next ID to allocate.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* Finds an empty entry in @xa between @limit.min and @limit.max,
|
|
* stores the index into the @id pointer, then stores the entry at
|
|
* that index. A concurrent lookup will not see an uninitialised @id.
|
|
* The search for an empty entry will start at @next and will wrap
|
|
* around if necessary.
|
|
*
|
|
* Context: Process context. Takes and releases the xa_lock while
|
|
* disabling interrupts. May sleep if the @gfp flags permit.
|
|
* Return: 0 if the allocation succeeded without wrapping. 1 if the
|
|
* allocation succeeded after wrapping, -ENOMEM if memory could not be
|
|
* allocated or -EBUSY if there are no free entries in @limit.
|
|
*/
|
|
static inline int xa_alloc_cyclic_irq(struct xarray *xa, u32 *id, void *entry,
|
|
struct xa_limit limit, u32 *next, gfp_t gfp)
|
|
{
|
|
int err;
|
|
|
|
xa_lock_irq(xa);
|
|
err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
|
|
xa_unlock_irq(xa);
|
|
|
|
return err;
|
|
}
|
|
|
|
/**
|
|
* xa_reserve() - Reserve this index in the XArray.
|
|
* @xa: XArray.
|
|
* @index: Index into array.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* Ensures there is somewhere to store an entry at @index in the array.
|
|
* If there is already something stored at @index, this function does
|
|
* nothing. If there was nothing there, the entry is marked as reserved.
|
|
* Loading from a reserved entry returns a %NULL pointer.
|
|
*
|
|
* If you do not use the entry that you have reserved, call xa_release()
|
|
* or xa_erase() to free any unnecessary memory.
|
|
*
|
|
* Context: Any context. Takes and releases the xa_lock.
|
|
* May sleep if the @gfp flags permit.
|
|
* Return: 0 if the reservation succeeded or -ENOMEM if it failed.
|
|
*/
|
|
static inline __must_check
|
|
int xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp)
|
|
{
|
|
return xa_err(xa_cmpxchg(xa, index, NULL, XA_ZERO_ENTRY, gfp));
|
|
}
|
|
|
|
/**
|
|
* xa_reserve_bh() - Reserve this index in the XArray.
|
|
* @xa: XArray.
|
|
* @index: Index into array.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* A softirq-disabling version of xa_reserve().
|
|
*
|
|
* Context: Any context. Takes and releases the xa_lock while
|
|
* disabling softirqs.
|
|
* Return: 0 if the reservation succeeded or -ENOMEM if it failed.
|
|
*/
|
|
static inline __must_check
|
|
int xa_reserve_bh(struct xarray *xa, unsigned long index, gfp_t gfp)
|
|
{
|
|
return xa_err(xa_cmpxchg_bh(xa, index, NULL, XA_ZERO_ENTRY, gfp));
|
|
}
|
|
|
|
/**
|
|
* xa_reserve_irq() - Reserve this index in the XArray.
|
|
* @xa: XArray.
|
|
* @index: Index into array.
|
|
* @gfp: Memory allocation flags.
|
|
*
|
|
* An interrupt-disabling version of xa_reserve().
|
|
*
|
|
* Context: Process context. Takes and releases the xa_lock while
|
|
* disabling interrupts.
|
|
* Return: 0 if the reservation succeeded or -ENOMEM if it failed.
|
|
*/
|
|
static inline __must_check
|
|
int xa_reserve_irq(struct xarray *xa, unsigned long index, gfp_t gfp)
|
|
{
|
|
return xa_err(xa_cmpxchg_irq(xa, index, NULL, XA_ZERO_ENTRY, gfp));
|
|
}
|
|
|
|
/**
|
|
* xa_release() - Release a reserved entry.
|
|
* @xa: XArray.
|
|
* @index: Index of entry.
|
|
*
|
|
* After calling xa_reserve(), you can call this function to release the
|
|
* reservation. If the entry at @index has been stored to, this function
|
|
* will do nothing.
|
|
*/
|
|
static inline void xa_release(struct xarray *xa, unsigned long index)
|
|
{
|
|
xa_cmpxchg(xa, index, XA_ZERO_ENTRY, NULL, 0);
|
|
}
|
|
|
|
/* Everything below here is the Advanced API. Proceed with caution. */
|
|
|
|
/*
|
|
* The xarray is constructed out of a set of 'chunks' of pointers. Choosing
|
|
* the best chunk size requires some tradeoffs. A power of two recommends
|
|
* itself so that we can walk the tree based purely on shifts and masks.
|
|
* Generally, the larger the better; as the number of slots per level of the
|
|
* tree increases, the less tall the tree needs to be. But that needs to be
|
|
* balanced against the memory consumption of each node. On a 64-bit system,
|
|
* xa_node is currently 576 bytes, and we get 7 of them per 4kB page. If we
|
|
* doubled the number of slots per node, we'd get only 3 nodes per 4kB page.
|
|
*/
|
|
#ifndef XA_CHUNK_SHIFT
|
|
#define XA_CHUNK_SHIFT (CONFIG_BASE_SMALL ? 4 : 6)
|
|
#endif
|
|
#define XA_CHUNK_SIZE (1UL << XA_CHUNK_SHIFT)
|
|
#define XA_CHUNK_MASK (XA_CHUNK_SIZE - 1)
|
|
#define XA_MAX_MARKS 3
|
|
#define XA_MARK_LONGS DIV_ROUND_UP(XA_CHUNK_SIZE, BITS_PER_LONG)
|
|
|
|
/*
|
|
* @count is the count of every non-NULL element in the ->slots array
|
|
* whether that is a value entry, a retry entry, a user pointer,
|
|
* a sibling entry or a pointer to the next level of the tree.
|
|
* @nr_values is the count of every element in ->slots which is
|
|
* either a value entry or a sibling of a value entry.
|
|
*/
|
|
struct xa_node {
|
|
unsigned char shift; /* Bits remaining in each slot */
|
|
unsigned char offset; /* Slot offset in parent */
|
|
unsigned char count; /* Total entry count */
|
|
unsigned char nr_values; /* Value entry count */
|
|
struct xa_node __rcu *parent; /* NULL at top of tree */
|
|
struct xarray *array; /* The array we belong to */
|
|
union {
|
|
struct list_head private_list; /* For tree user */
|
|
struct rcu_head rcu_head; /* Used when freeing node */
|
|
};
|
|
void __rcu *slots[XA_CHUNK_SIZE];
|
|
union {
|
|
unsigned long tags[XA_MAX_MARKS][XA_MARK_LONGS];
|
|
unsigned long marks[XA_MAX_MARKS][XA_MARK_LONGS];
|
|
};
|
|
};
|
|
|
|
void xa_dump(const struct xarray *);
|
|
void xa_dump_node(const struct xa_node *);
|
|
|
|
#ifdef XA_DEBUG
|
|
#define XA_BUG_ON(xa, x) do { \
|
|
if (x) { \
|
|
xa_dump(xa); \
|
|
BUG(); \
|
|
} \
|
|
} while (0)
|
|
#define XA_NODE_BUG_ON(node, x) do { \
|
|
if (x) { \
|
|
if (node) xa_dump_node(node); \
|
|
BUG(); \
|
|
} \
|
|
} while (0)
|
|
#else
|
|
#define XA_BUG_ON(xa, x) do { } while (0)
|
|
#define XA_NODE_BUG_ON(node, x) do { } while (0)
|
|
#endif
|
|
|
|
/* Private */
|
|
static inline void *xa_head(const struct xarray *xa)
|
|
{
|
|
return rcu_dereference_check(xa->xa_head,
|
|
lockdep_is_held(&xa->xa_lock));
|
|
}
|
|
|
|
/* Private */
|
|
static inline void *xa_head_locked(const struct xarray *xa)
|
|
{
|
|
return rcu_dereference_protected(xa->xa_head,
|
|
lockdep_is_held(&xa->xa_lock));
|
|
}
|
|
|
|
/* Private */
|
|
static inline void *xa_entry(const struct xarray *xa,
|
|
const struct xa_node *node, unsigned int offset)
|
|
{
|
|
XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
|
|
return rcu_dereference_check(node->slots[offset],
|
|
lockdep_is_held(&xa->xa_lock));
|
|
}
|
|
|
|
/* Private */
|
|
static inline void *xa_entry_locked(const struct xarray *xa,
|
|
const struct xa_node *node, unsigned int offset)
|
|
{
|
|
XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
|
|
return rcu_dereference_protected(node->slots[offset],
|
|
lockdep_is_held(&xa->xa_lock));
|
|
}
|
|
|
|
/* Private */
|
|
static inline struct xa_node *xa_parent(const struct xarray *xa,
|
|
const struct xa_node *node)
|
|
{
|
|
return rcu_dereference_check(node->parent,
|
|
lockdep_is_held(&xa->xa_lock));
|
|
}
|
|
|
|
/* Private */
|
|
static inline struct xa_node *xa_parent_locked(const struct xarray *xa,
|
|
const struct xa_node *node)
|
|
{
|
|
return rcu_dereference_protected(node->parent,
|
|
lockdep_is_held(&xa->xa_lock));
|
|
}
|
|
|
|
/* Private */
|
|
static inline void *xa_mk_node(const struct xa_node *node)
|
|
{
|
|
return (void *)((unsigned long)node | 2);
|
|
}
|
|
|
|
/* Private */
|
|
static inline struct xa_node *xa_to_node(const void *entry)
|
|
{
|
|
return (struct xa_node *)((unsigned long)entry - 2);
|
|
}
|
|
|
|
/* Private */
|
|
static inline bool xa_is_node(const void *entry)
|
|
{
|
|
return xa_is_internal(entry) && (unsigned long)entry > 4096;
|
|
}
|
|
|
|
/* Private */
|
|
static inline void *xa_mk_sibling(unsigned int offset)
|
|
{
|
|
return xa_mk_internal(offset);
|
|
}
|
|
|
|
/* Private */
|
|
static inline unsigned long xa_to_sibling(const void *entry)
|
|
{
|
|
return xa_to_internal(entry);
|
|
}
|
|
|
|
/**
|
|
* xa_is_sibling() - Is the entry a sibling entry?
|
|
* @entry: Entry retrieved from the XArray
|
|
*
|
|
* Return: %true if the entry is a sibling entry.
|
|
*/
|
|
static inline bool xa_is_sibling(const void *entry)
|
|
{
|
|
return IS_ENABLED(CONFIG_XARRAY_MULTI) && xa_is_internal(entry) &&
|
|
(entry < xa_mk_sibling(XA_CHUNK_SIZE - 1));
|
|
}
|
|
|
|
#define XA_RETRY_ENTRY xa_mk_internal(256)
|
|
|
|
/**
|
|
* xa_is_retry() - Is the entry a retry entry?
|
|
* @entry: Entry retrieved from the XArray
|
|
*
|
|
* Return: %true if the entry is a retry entry.
|
|
*/
|
|
static inline bool xa_is_retry(const void *entry)
|
|
{
|
|
return unlikely(entry == XA_RETRY_ENTRY);
|
|
}
|
|
|
|
/**
|
|
* xa_is_advanced() - Is the entry only permitted for the advanced API?
|
|
* @entry: Entry to be stored in the XArray.
|
|
*
|
|
* Return: %true if the entry cannot be stored by the normal API.
|
|
*/
|
|
static inline bool xa_is_advanced(const void *entry)
|
|
{
|
|
return xa_is_internal(entry) && (entry <= XA_RETRY_ENTRY);
|
|
}
|
|
|
|
/**
|
|
* typedef xa_update_node_t - A callback function from the XArray.
|
|
* @node: The node which is being processed
|
|
*
|
|
* This function is called every time the XArray updates the count of
|
|
* present and value entries in a node. It allows advanced users to
|
|
* maintain the private_list in the node.
|
|
*
|
|
* Context: The xa_lock is held and interrupts may be disabled.
|
|
* Implementations should not drop the xa_lock, nor re-enable
|
|
* interrupts.
|
|
*/
|
|
typedef void (*xa_update_node_t)(struct xa_node *node);
|
|
|
|
/*
|
|
* The xa_state is opaque to its users. It contains various different pieces
|
|
* of state involved in the current operation on the XArray. It should be
|
|
* declared on the stack and passed between the various internal routines.
|
|
* The various elements in it should not be accessed directly, but only
|
|
* through the provided accessor functions. The below documentation is for
|
|
* the benefit of those working on the code, not for users of the XArray.
|
|
*
|
|
* @xa_node usually points to the xa_node containing the slot we're operating
|
|
* on (and @xa_offset is the offset in the slots array). If there is a
|
|
* single entry in the array at index 0, there are no allocated xa_nodes to
|
|
* point to, and so we store %NULL in @xa_node. @xa_node is set to
|
|
* the value %XAS_RESTART if the xa_state is not walked to the correct
|
|
* position in the tree of nodes for this operation. If an error occurs
|
|
* during an operation, it is set to an %XAS_ERROR value. If we run off the
|
|
* end of the allocated nodes, it is set to %XAS_BOUNDS.
|
|
*/
|
|
struct xa_state {
|
|
struct xarray *xa;
|
|
unsigned long xa_index;
|
|
unsigned char xa_shift;
|
|
unsigned char xa_sibs;
|
|
unsigned char xa_offset;
|
|
unsigned char xa_pad; /* Helps gcc generate better code */
|
|
struct xa_node *xa_node;
|
|
struct xa_node *xa_alloc;
|
|
xa_update_node_t xa_update;
|
|
};
|
|
|
|
/*
|
|
* We encode errnos in the xas->xa_node. If an error has happened, we need to
|
|
* drop the lock to fix it, and once we've done so the xa_state is invalid.
|
|
*/
|
|
#define XA_ERROR(errno) ((struct xa_node *)(((unsigned long)errno << 2) | 2UL))
|
|
#define XAS_BOUNDS ((struct xa_node *)1UL)
|
|
#define XAS_RESTART ((struct xa_node *)3UL)
|
|
|
|
#define __XA_STATE(array, index, shift, sibs) { \
|
|
.xa = array, \
|
|
.xa_index = index, \
|
|
.xa_shift = shift, \
|
|
.xa_sibs = sibs, \
|
|
.xa_offset = 0, \
|
|
.xa_pad = 0, \
|
|
.xa_node = XAS_RESTART, \
|
|
.xa_alloc = NULL, \
|
|
.xa_update = NULL \
|
|
}
|
|
|
|
/**
|
|
* XA_STATE() - Declare an XArray operation state.
|
|
* @name: Name of this operation state (usually xas).
|
|
* @array: Array to operate on.
|
|
* @index: Initial index of interest.
|
|
*
|
|
* Declare and initialise an xa_state on the stack.
|
|
*/
|
|
#define XA_STATE(name, array, index) \
|
|
struct xa_state name = __XA_STATE(array, index, 0, 0)
|
|
|
|
/**
|
|
* XA_STATE_ORDER() - Declare an XArray operation state.
|
|
* @name: Name of this operation state (usually xas).
|
|
* @array: Array to operate on.
|
|
* @index: Initial index of interest.
|
|
* @order: Order of entry.
|
|
*
|
|
* Declare and initialise an xa_state on the stack. This variant of
|
|
* XA_STATE() allows you to specify the 'order' of the element you
|
|
* want to operate on.`
|
|
*/
|
|
#define XA_STATE_ORDER(name, array, index, order) \
|
|
struct xa_state name = __XA_STATE(array, \
|
|
(index >> order) << order, \
|
|
order - (order % XA_CHUNK_SHIFT), \
|
|
(1U << (order % XA_CHUNK_SHIFT)) - 1)
|
|
|
|
#define xas_marked(xas, mark) xa_marked((xas)->xa, (mark))
|
|
#define xas_trylock(xas) xa_trylock((xas)->xa)
|
|
#define xas_lock(xas) xa_lock((xas)->xa)
|
|
#define xas_unlock(xas) xa_unlock((xas)->xa)
|
|
#define xas_lock_bh(xas) xa_lock_bh((xas)->xa)
|
|
#define xas_unlock_bh(xas) xa_unlock_bh((xas)->xa)
|
|
#define xas_lock_irq(xas) xa_lock_irq((xas)->xa)
|
|
#define xas_unlock_irq(xas) xa_unlock_irq((xas)->xa)
|
|
#define xas_lock_irqsave(xas, flags) \
|
|
xa_lock_irqsave((xas)->xa, flags)
|
|
#define xas_unlock_irqrestore(xas, flags) \
|
|
xa_unlock_irqrestore((xas)->xa, flags)
|
|
|
|
/**
|
|
* xas_error() - Return an errno stored in the xa_state.
|
|
* @xas: XArray operation state.
|
|
*
|
|
* Return: 0 if no error has been noted. A negative errno if one has.
|
|
*/
|
|
static inline int xas_error(const struct xa_state *xas)
|
|
{
|
|
return xa_err(xas->xa_node);
|
|
}
|
|
|
|
/**
|
|
* xas_set_err() - Note an error in the xa_state.
|
|
* @xas: XArray operation state.
|
|
* @err: Negative error number.
|
|
*
|
|
* Only call this function with a negative @err; zero or positive errors
|
|
* will probably not behave the way you think they should. If you want
|
|
* to clear the error from an xa_state, use xas_reset().
|
|
*/
|
|
static inline void xas_set_err(struct xa_state *xas, long err)
|
|
{
|
|
xas->xa_node = XA_ERROR(err);
|
|
}
|
|
|
|
/**
|
|
* xas_invalid() - Is the xas in a retry or error state?
|
|
* @xas: XArray operation state.
|
|
*
|
|
* Return: %true if the xas cannot be used for operations.
|
|
*/
|
|
static inline bool xas_invalid(const struct xa_state *xas)
|
|
{
|
|
return (unsigned long)xas->xa_node & 3;
|
|
}
|
|
|
|
/**
|
|
* xas_valid() - Is the xas a valid cursor into the array?
|
|
* @xas: XArray operation state.
|
|
*
|
|
* Return: %true if the xas can be used for operations.
|
|
*/
|
|
static inline bool xas_valid(const struct xa_state *xas)
|
|
{
|
|
return !xas_invalid(xas);
|
|
}
|
|
|
|
/**
|
|
* xas_is_node() - Does the xas point to a node?
|
|
* @xas: XArray operation state.
|
|
*
|
|
* Return: %true if the xas currently references a node.
|
|
*/
|
|
static inline bool xas_is_node(const struct xa_state *xas)
|
|
{
|
|
return xas_valid(xas) && xas->xa_node;
|
|
}
|
|
|
|
/* True if the pointer is something other than a node */
|
|
static inline bool xas_not_node(struct xa_node *node)
|
|
{
|
|
return ((unsigned long)node & 3) || !node;
|
|
}
|
|
|
|
/* True if the node represents RESTART or an error */
|
|
static inline bool xas_frozen(struct xa_node *node)
|
|
{
|
|
return (unsigned long)node & 2;
|
|
}
|
|
|
|
/* True if the node represents head-of-tree, RESTART or BOUNDS */
|
|
static inline bool xas_top(struct xa_node *node)
|
|
{
|
|
return node <= XAS_RESTART;
|
|
}
|
|
|
|
/**
|
|
* xas_reset() - Reset an XArray operation state.
|
|
* @xas: XArray operation state.
|
|
*
|
|
* Resets the error or walk state of the @xas so future walks of the
|
|
* array will start from the root. Use this if you have dropped the
|
|
* xarray lock and want to reuse the xa_state.
|
|
*
|
|
* Context: Any context.
|
|
*/
|
|
static inline void xas_reset(struct xa_state *xas)
|
|
{
|
|
xas->xa_node = XAS_RESTART;
|
|
}
|
|
|
|
/**
|
|
* xas_retry() - Retry the operation if appropriate.
|
|
* @xas: XArray operation state.
|
|
* @entry: Entry from xarray.
|
|
*
|
|
* The advanced functions may sometimes return an internal entry, such as
|
|
* a retry entry or a zero entry. This function sets up the @xas to restart
|
|
* the walk from the head of the array if needed.
|
|
*
|
|
* Context: Any context.
|
|
* Return: true if the operation needs to be retried.
|
|
*/
|
|
static inline bool xas_retry(struct xa_state *xas, const void *entry)
|
|
{
|
|
if (xa_is_zero(entry))
|
|
return true;
|
|
if (!xa_is_retry(entry))
|
|
return false;
|
|
xas_reset(xas);
|
|
return true;
|
|
}
|
|
|
|
void *xas_load(struct xa_state *);
|
|
void *xas_store(struct xa_state *, void *entry);
|
|
void *xas_find(struct xa_state *, unsigned long max);
|
|
void *xas_find_conflict(struct xa_state *);
|
|
|
|
bool xas_get_mark(const struct xa_state *, xa_mark_t);
|
|
void xas_set_mark(const struct xa_state *, xa_mark_t);
|
|
void xas_clear_mark(const struct xa_state *, xa_mark_t);
|
|
void *xas_find_marked(struct xa_state *, unsigned long max, xa_mark_t);
|
|
void xas_init_marks(const struct xa_state *);
|
|
|
|
bool xas_nomem(struct xa_state *, gfp_t);
|
|
void xas_pause(struct xa_state *);
|
|
|
|
void xas_create_range(struct xa_state *);
|
|
|
|
/**
|
|
* xas_reload() - Refetch an entry from the xarray.
|
|
* @xas: XArray operation state.
|
|
*
|
|
* Use this function to check that a previously loaded entry still has
|
|
* the same value. This is useful for the lockless pagecache lookup where
|
|
* we walk the array with only the RCU lock to protect us, lock the page,
|
|
* then check that the page hasn't moved since we looked it up.
|
|
*
|
|
* The caller guarantees that @xas is still valid. If it may be in an
|
|
* error or restart state, call xas_load() instead.
|
|
*
|
|
* Return: The entry at this location in the xarray.
|
|
*/
|
|
static inline void *xas_reload(struct xa_state *xas)
|
|
{
|
|
struct xa_node *node = xas->xa_node;
|
|
|
|
if (node)
|
|
return xa_entry(xas->xa, node, xas->xa_offset);
|
|
return xa_head(xas->xa);
|
|
}
|
|
|
|
/**
|
|
* xas_set() - Set up XArray operation state for a different index.
|
|
* @xas: XArray operation state.
|
|
* @index: New index into the XArray.
|
|
*
|
|
* Move the operation state to refer to a different index. This will
|
|
* have the effect of starting a walk from the top; see xas_next()
|
|
* to move to an adjacent index.
|
|
*/
|
|
static inline void xas_set(struct xa_state *xas, unsigned long index)
|
|
{
|
|
xas->xa_index = index;
|
|
xas->xa_node = XAS_RESTART;
|
|
}
|
|
|
|
/**
|
|
* xas_set_order() - Set up XArray operation state for a multislot entry.
|
|
* @xas: XArray operation state.
|
|
* @index: Target of the operation.
|
|
* @order: Entry occupies 2^@order indices.
|
|
*/
|
|
static inline void xas_set_order(struct xa_state *xas, unsigned long index,
|
|
unsigned int order)
|
|
{
|
|
#ifdef CONFIG_XARRAY_MULTI
|
|
xas->xa_index = order < BITS_PER_LONG ? (index >> order) << order : 0;
|
|
xas->xa_shift = order - (order % XA_CHUNK_SHIFT);
|
|
xas->xa_sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
|
|
xas->xa_node = XAS_RESTART;
|
|
#else
|
|
BUG_ON(order > 0);
|
|
xas_set(xas, index);
|
|
#endif
|
|
}
|
|
|
|
/**
|
|
* xas_set_update() - Set up XArray operation state for a callback.
|
|
* @xas: XArray operation state.
|
|
* @update: Function to call when updating a node.
|
|
*
|
|
* The XArray can notify a caller after it has updated an xa_node.
|
|
* This is advanced functionality and is only needed by the page cache.
|
|
*/
|
|
static inline void xas_set_update(struct xa_state *xas, xa_update_node_t update)
|
|
{
|
|
xas->xa_update = update;
|
|
}
|
|
|
|
/**
|
|
* xas_next_entry() - Advance iterator to next present entry.
|
|
* @xas: XArray operation state.
|
|
* @max: Highest index to return.
|
|
*
|
|
* xas_next_entry() is an inline function to optimise xarray traversal for
|
|
* speed. It is equivalent to calling xas_find(), and will call xas_find()
|
|
* for all the hard cases.
|
|
*
|
|
* Return: The next present entry after the one currently referred to by @xas.
|
|
*/
|
|
static inline void *xas_next_entry(struct xa_state *xas, unsigned long max)
|
|
{
|
|
struct xa_node *node = xas->xa_node;
|
|
void *entry;
|
|
|
|
if (unlikely(xas_not_node(node) || node->shift ||
|
|
xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)))
|
|
return xas_find(xas, max);
|
|
|
|
do {
|
|
if (unlikely(xas->xa_index >= max))
|
|
return xas_find(xas, max);
|
|
if (unlikely(xas->xa_offset == XA_CHUNK_MASK))
|
|
return xas_find(xas, max);
|
|
entry = xa_entry(xas->xa, node, xas->xa_offset + 1);
|
|
if (unlikely(xa_is_internal(entry)))
|
|
return xas_find(xas, max);
|
|
xas->xa_offset++;
|
|
xas->xa_index++;
|
|
} while (!entry);
|
|
|
|
return entry;
|
|
}
|
|
|
|
/* Private */
|
|
static inline unsigned int xas_find_chunk(struct xa_state *xas, bool advance,
|
|
xa_mark_t mark)
|
|
{
|
|
unsigned long *addr = xas->xa_node->marks[(__force unsigned)mark];
|
|
unsigned int offset = xas->xa_offset;
|
|
|
|
if (advance)
|
|
offset++;
|
|
if (XA_CHUNK_SIZE == BITS_PER_LONG) {
|
|
if (offset < XA_CHUNK_SIZE) {
|
|
unsigned long data = *addr & (~0UL << offset);
|
|
if (data)
|
|
return __ffs(data);
|
|
}
|
|
return XA_CHUNK_SIZE;
|
|
}
|
|
|
|
return find_next_bit(addr, XA_CHUNK_SIZE, offset);
|
|
}
|
|
|
|
/**
|
|
* xas_next_marked() - Advance iterator to next marked entry.
|
|
* @xas: XArray operation state.
|
|
* @max: Highest index to return.
|
|
* @mark: Mark to search for.
|
|
*
|
|
* xas_next_marked() is an inline function to optimise xarray traversal for
|
|
* speed. It is equivalent to calling xas_find_marked(), and will call
|
|
* xas_find_marked() for all the hard cases.
|
|
*
|
|
* Return: The next marked entry after the one currently referred to by @xas.
|
|
*/
|
|
static inline void *xas_next_marked(struct xa_state *xas, unsigned long max,
|
|
xa_mark_t mark)
|
|
{
|
|
struct xa_node *node = xas->xa_node;
|
|
unsigned int offset;
|
|
|
|
if (unlikely(xas_not_node(node) || node->shift))
|
|
return xas_find_marked(xas, max, mark);
|
|
offset = xas_find_chunk(xas, true, mark);
|
|
xas->xa_offset = offset;
|
|
xas->xa_index = (xas->xa_index & ~XA_CHUNK_MASK) + offset;
|
|
if (xas->xa_index > max)
|
|
return NULL;
|
|
if (offset == XA_CHUNK_SIZE)
|
|
return xas_find_marked(xas, max, mark);
|
|
return xa_entry(xas->xa, node, offset);
|
|
}
|
|
|
|
/*
|
|
* If iterating while holding a lock, drop the lock and reschedule
|
|
* every %XA_CHECK_SCHED loops.
|
|
*/
|
|
enum {
|
|
XA_CHECK_SCHED = 4096,
|
|
};
|
|
|
|
/**
|
|
* xas_for_each() - Iterate over a range of an XArray.
|
|
* @xas: XArray operation state.
|
|
* @entry: Entry retrieved from the array.
|
|
* @max: Maximum index to retrieve from array.
|
|
*
|
|
* The loop body will be executed for each entry present in the xarray
|
|
* between the current xas position and @max. @entry will be set to
|
|
* the entry retrieved from the xarray. It is safe to delete entries
|
|
* from the array in the loop body. You should hold either the RCU lock
|
|
* or the xa_lock while iterating. If you need to drop the lock, call
|
|
* xas_pause() first.
|
|
*/
|
|
#define xas_for_each(xas, entry, max) \
|
|
for (entry = xas_find(xas, max); entry; \
|
|
entry = xas_next_entry(xas, max))
|
|
|
|
/**
|
|
* xas_for_each_marked() - Iterate over a range of an XArray.
|
|
* @xas: XArray operation state.
|
|
* @entry: Entry retrieved from the array.
|
|
* @max: Maximum index to retrieve from array.
|
|
* @mark: Mark to search for.
|
|
*
|
|
* The loop body will be executed for each marked entry in the xarray
|
|
* between the current xas position and @max. @entry will be set to
|
|
* the entry retrieved from the xarray. It is safe to delete entries
|
|
* from the array in the loop body. You should hold either the RCU lock
|
|
* or the xa_lock while iterating. If you need to drop the lock, call
|
|
* xas_pause() first.
|
|
*/
|
|
#define xas_for_each_marked(xas, entry, max, mark) \
|
|
for (entry = xas_find_marked(xas, max, mark); entry; \
|
|
entry = xas_next_marked(xas, max, mark))
|
|
|
|
/**
|
|
* xas_for_each_conflict() - Iterate over a range of an XArray.
|
|
* @xas: XArray operation state.
|
|
* @entry: Entry retrieved from the array.
|
|
*
|
|
* The loop body will be executed for each entry in the XArray that lies
|
|
* within the range specified by @xas. If the loop completes successfully,
|
|
* any entries that lie in this range will be replaced by @entry. The caller
|
|
* may break out of the loop; if they do so, the contents of the XArray will
|
|
* be unchanged. The operation may fail due to an out of memory condition.
|
|
* The caller may also call xa_set_err() to exit the loop while setting an
|
|
* error to record the reason.
|
|
*/
|
|
#define xas_for_each_conflict(xas, entry) \
|
|
while ((entry = xas_find_conflict(xas)))
|
|
|
|
void *__xas_next(struct xa_state *);
|
|
void *__xas_prev(struct xa_state *);
|
|
|
|
/**
|
|
* xas_prev() - Move iterator to previous index.
|
|
* @xas: XArray operation state.
|
|
*
|
|
* If the @xas was in an error state, it will remain in an error state
|
|
* and this function will return %NULL. If the @xas has never been walked,
|
|
* it will have the effect of calling xas_load(). Otherwise one will be
|
|
* subtracted from the index and the state will be walked to the correct
|
|
* location in the array for the next operation.
|
|
*
|
|
* If the iterator was referencing index 0, this function wraps
|
|
* around to %ULONG_MAX.
|
|
*
|
|
* Return: The entry at the new index. This may be %NULL or an internal
|
|
* entry.
|
|
*/
|
|
static inline void *xas_prev(struct xa_state *xas)
|
|
{
|
|
struct xa_node *node = xas->xa_node;
|
|
|
|
if (unlikely(xas_not_node(node) || node->shift ||
|
|
xas->xa_offset == 0))
|
|
return __xas_prev(xas);
|
|
|
|
xas->xa_index--;
|
|
xas->xa_offset--;
|
|
return xa_entry(xas->xa, node, xas->xa_offset);
|
|
}
|
|
|
|
/**
|
|
* xas_next() - Move state to next index.
|
|
* @xas: XArray operation state.
|
|
*
|
|
* If the @xas was in an error state, it will remain in an error state
|
|
* and this function will return %NULL. If the @xas has never been walked,
|
|
* it will have the effect of calling xas_load(). Otherwise one will be
|
|
* added to the index and the state will be walked to the correct
|
|
* location in the array for the next operation.
|
|
*
|
|
* If the iterator was referencing index %ULONG_MAX, this function wraps
|
|
* around to 0.
|
|
*
|
|
* Return: The entry at the new index. This may be %NULL or an internal
|
|
* entry.
|
|
*/
|
|
static inline void *xas_next(struct xa_state *xas)
|
|
{
|
|
struct xa_node *node = xas->xa_node;
|
|
|
|
if (unlikely(xas_not_node(node) || node->shift ||
|
|
xas->xa_offset == XA_CHUNK_MASK))
|
|
return __xas_next(xas);
|
|
|
|
xas->xa_index++;
|
|
xas->xa_offset++;
|
|
return xa_entry(xas->xa, node, xas->xa_offset);
|
|
}
|
|
|
|
#endif /* _LINUX_XARRAY_H */
|