2018-04-10 17:36:52 -06:00
|
|
|
/* SPDX-License-Identifier: GPL-2.0+ */
|
|
|
|
#ifndef _LINUX_XARRAY_H
|
|
|
|
#define _LINUX_XARRAY_H
|
|
|
|
/*
|
|
|
|
* eXtensible Arrays
|
|
|
|
* Copyright (c) 2017 Microsoft Corporation
|
2018-06-16 15:32:07 -06:00
|
|
|
* Author: Matthew Wilcox <willy@infradead.org>
|
2017-11-03 11:30:42 -06:00
|
|
|
*
|
|
|
|
* See Documentation/core-api/xarray.rst for how to use the XArray.
|
2018-04-10 17:36:52 -06:00
|
|
|
*/
|
|
|
|
|
2017-11-03 11:30:42 -06:00
|
|
|
#include <linux/bug.h>
|
2017-11-07 14:30:10 -07:00
|
|
|
#include <linux/compiler.h>
|
2017-11-10 07:34:31 -07:00
|
|
|
#include <linux/gfp.h>
|
2017-11-07 14:30:10 -07:00
|
|
|
#include <linux/kconfig.h>
|
2017-11-07 12:57:46 -07:00
|
|
|
#include <linux/kernel.h>
|
|
|
|
#include <linux/rcupdate.h>
|
2018-04-10 17:36:52 -06:00
|
|
|
#include <linux/spinlock.h>
|
2017-11-03 11:30:42 -06:00
|
|
|
#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.
|
2017-11-03 21:09:45 -06:00
|
|
|
*
|
|
|
|
* Most internal entries are pointers to the next node in the tree.
|
|
|
|
* The following internal entries have a special meaning:
|
|
|
|
*
|
|
|
|
* 0-62: Sibling entries
|
|
|
|
* 256: Retry entry
|
2017-11-07 12:57:46 -07:00
|
|
|
*
|
|
|
|
* Errors are also represented as internal entries, but use the negative
|
|
|
|
* space (-4094 to -2). They're never stored in the slots array; only
|
|
|
|
* returned by the normal API.
|
2017-11-03 11:30:42 -06:00
|
|
|
*/
|
|
|
|
|
|
|
|
#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;
|
|
|
|
}
|
2018-04-10 17:36:52 -06:00
|
|
|
|
2017-11-03 21:09:45 -06:00
|
|
|
/*
|
|
|
|
* xa_mk_internal() - Create an internal entry.
|
|
|
|
* @v: Value to turn into an internal entry.
|
|
|
|
*
|
|
|
|
* Context: Any context.
|
|
|
|
* Return: An XArray internal entry corresponding to this value.
|
|
|
|
*/
|
|
|
|
static inline void *xa_mk_internal(unsigned long v)
|
|
|
|
{
|
|
|
|
return (void *)((v << 2) | 2);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* xa_to_internal() - Extract the value from an internal entry.
|
|
|
|
* @entry: XArray entry.
|
|
|
|
*
|
|
|
|
* Context: Any context.
|
|
|
|
* Return: The value which was stored in the internal entry.
|
|
|
|
*/
|
|
|
|
static inline unsigned long xa_to_internal(const void *entry)
|
|
|
|
{
|
|
|
|
return (unsigned long)entry >> 2;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* xa_is_internal() - Is the entry an internal entry?
|
|
|
|
* @entry: XArray entry.
|
|
|
|
*
|
|
|
|
* Context: Any context.
|
|
|
|
* Return: %true if the entry is an internal entry.
|
|
|
|
*/
|
|
|
|
static inline bool xa_is_internal(const void *entry)
|
|
|
|
{
|
|
|
|
return ((unsigned long)entry & 3) == 2;
|
|
|
|
}
|
|
|
|
|
2017-11-07 12:57:46 -07:00
|
|
|
/**
|
|
|
|
* xa_is_err() - Report whether an XArray operation returned an error
|
|
|
|
* @entry: Result from calling an XArray function
|
|
|
|
*
|
|
|
|
* If an XArray operation cannot complete an operation, it will return
|
|
|
|
* a special value indicating an error. This function tells you
|
|
|
|
* whether an error occurred; xa_err() tells you which error occurred.
|
|
|
|
*
|
|
|
|
* Context: Any context.
|
|
|
|
* Return: %true if the entry indicates an error.
|
|
|
|
*/
|
|
|
|
static inline bool xa_is_err(const void *entry)
|
|
|
|
{
|
|
|
|
return unlikely(xa_is_internal(entry));
|
|
|
|
}
|
|
|
|
|
|
|
|
/**
|
|
|
|
* xa_err() - Turn an XArray result into an errno.
|
|
|
|
* @entry: Result from calling an XArray function.
|
|
|
|
*
|
|
|
|
* If an XArray operation cannot complete an operation, it will return
|
|
|
|
* a special pointer value which encodes an errno. This function extracts
|
|
|
|
* the errno from the pointer value, or returns 0 if the pointer does not
|
|
|
|
* represent an errno.
|
|
|
|
*
|
|
|
|
* Context: Any context.
|
|
|
|
* Return: A negative errno or 0.
|
|
|
|
*/
|
|
|
|
static inline int xa_err(void *entry)
|
|
|
|
{
|
|
|
|
/* xa_to_internal() would not do sign extension. */
|
|
|
|
if (xa_is_err(entry))
|
|
|
|
return (long)entry >> 2;
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
2017-11-10 07:34:31 -07:00
|
|
|
typedef unsigned __bitwise xa_mark_t;
|
|
|
|
#define XA_MARK_0 ((__force xa_mark_t)0U)
|
|
|
|
#define XA_MARK_1 ((__force xa_mark_t)1U)
|
|
|
|
#define XA_MARK_2 ((__force xa_mark_t)2U)
|
|
|
|
#define XA_PRESENT ((__force xa_mark_t)8U)
|
|
|
|
#define XA_MARK_MAX XA_MARK_2
|
|
|
|
|
2017-11-10 13:15:08 -07:00
|
|
|
enum xa_lock_type {
|
|
|
|
XA_LOCK_IRQ = 1,
|
|
|
|
XA_LOCK_BH = 2,
|
|
|
|
};
|
|
|
|
|
2017-11-10 07:34:31 -07:00
|
|
|
/*
|
|
|
|
* Values for xa_flags. The radix tree stores its GFP flags in the xa_flags,
|
|
|
|
* and we remain compatible with that.
|
|
|
|
*/
|
2017-11-10 13:15:08 -07:00
|
|
|
#define XA_FLAGS_LOCK_IRQ ((__force gfp_t)XA_LOCK_IRQ)
|
|
|
|
#define XA_FLAGS_LOCK_BH ((__force gfp_t)XA_LOCK_BH)
|
2017-11-10 07:34:31 -07:00
|
|
|
#define XA_FLAGS_MARK(mark) ((__force gfp_t)((1U << __GFP_BITS_SHIFT) << \
|
|
|
|
(__force unsigned)(mark)))
|
|
|
|
|
2017-11-07 14:30:10 -07:00
|
|
|
/**
|
|
|
|
* struct xarray - The anchor of the XArray.
|
|
|
|
* @xa_lock: Lock that protects the contents of the XArray.
|
|
|
|
*
|
|
|
|
* To use the xarray, define it statically or embed it in your data structure.
|
|
|
|
* It is a very small data structure, so it does not usually make sense to
|
|
|
|
* allocate it separately and keep a pointer to it in your data structure.
|
|
|
|
*
|
|
|
|
* You may use the xa_lock to protect your own data structures as well.
|
|
|
|
*/
|
|
|
|
/*
|
|
|
|
* If all of the entries in the array are NULL, @xa_head is a NULL pointer.
|
|
|
|
* If the only non-NULL entry in the array is at index 0, @xa_head is that
|
|
|
|
* entry. If any other entry in the array is non-NULL, @xa_head points
|
|
|
|
* to an @xa_node.
|
|
|
|
*/
|
|
|
|
struct xarray {
|
|
|
|
spinlock_t xa_lock;
|
|
|
|
/* private: The rest of the data structure is not to be used directly. */
|
|
|
|
gfp_t xa_flags;
|
|
|
|
void __rcu * xa_head;
|
|
|
|
};
|
|
|
|
|
|
|
|
#define XARRAY_INIT(name, flags) { \
|
|
|
|
.xa_lock = __SPIN_LOCK_UNLOCKED(name.xa_lock), \
|
|
|
|
.xa_flags = flags, \
|
|
|
|
.xa_head = NULL, \
|
|
|
|
}
|
|
|
|
|
|
|
|
/**
|
|
|
|
* DEFINE_XARRAY_FLAGS() - Define an XArray with custom flags.
|
|
|
|
* @name: A string that names your XArray.
|
|
|
|
* @flags: XA_FLAG values.
|
|
|
|
*
|
|
|
|
* This is intended for file scope definitions of XArrays. It declares
|
|
|
|
* and initialises an empty XArray with the chosen name and flags. It is
|
|
|
|
* equivalent to calling xa_init_flags() on the array, but it does the
|
|
|
|
* initialisation at compiletime instead of runtime.
|
|
|
|
*/
|
|
|
|
#define DEFINE_XARRAY_FLAGS(name, flags) \
|
|
|
|
struct xarray name = XARRAY_INIT(name, flags)
|
|
|
|
|
|
|
|
/**
|
|
|
|
* DEFINE_XARRAY() - Define an XArray.
|
|
|
|
* @name: A string that names your XArray.
|
|
|
|
*
|
|
|
|
* This is intended for file scope definitions of XArrays. It declares
|
|
|
|
* and initialises an empty XArray with the chosen name. It is equivalent
|
|
|
|
* to calling xa_init() on the array, but it does the initialisation at
|
|
|
|
* compiletime instead of runtime.
|
|
|
|
*/
|
|
|
|
#define DEFINE_XARRAY(name) DEFINE_XARRAY_FLAGS(name, 0)
|
|
|
|
|
|
|
|
void xa_init_flags(struct xarray *, gfp_t flags);
|
2017-11-07 12:57:46 -07:00
|
|
|
void *xa_load(struct xarray *, unsigned long index);
|
2017-11-10 13:15:08 -07:00
|
|
|
void *xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
|
2017-11-10 13:34:55 -07:00
|
|
|
void *xa_cmpxchg(struct xarray *, unsigned long index,
|
|
|
|
void *old, void *entry, gfp_t);
|
2017-11-10 07:34:31 -07:00
|
|
|
bool xa_get_mark(struct xarray *, unsigned long index, xa_mark_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);
|
2017-11-07 14:30:10 -07:00
|
|
|
|
|
|
|
/**
|
|
|
|
* xa_init() - Initialise an empty XArray.
|
|
|
|
* @xa: XArray.
|
|
|
|
*
|
|
|
|
* An empty XArray is full of NULL entries.
|
|
|
|
*
|
|
|
|
* Context: Any context.
|
|
|
|
*/
|
|
|
|
static inline void xa_init(struct xarray *xa)
|
|
|
|
{
|
|
|
|
xa_init_flags(xa, 0);
|
|
|
|
}
|
|
|
|
|
2017-11-07 12:57:46 -07:00
|
|
|
/**
|
|
|
|
* xa_empty() - Determine if an array has any present entries.
|
|
|
|
* @xa: XArray.
|
|
|
|
*
|
|
|
|
* Context: Any context.
|
|
|
|
* Return: %true if the array contains only NULL pointers.
|
|
|
|
*/
|
|
|
|
static inline bool xa_empty(const struct xarray *xa)
|
|
|
|
{
|
|
|
|
return xa->xa_head == NULL;
|
|
|
|
}
|
|
|
|
|
2017-11-10 07:34:31 -07:00
|
|
|
/**
|
|
|
|
* xa_marked() - Inquire whether any entry in this array has a mark set
|
|
|
|
* @xa: Array
|
|
|
|
* @mark: Mark value
|
|
|
|
*
|
|
|
|
* Context: Any context.
|
|
|
|
* Return: %true if any entry has this mark set.
|
|
|
|
*/
|
|
|
|
static inline bool xa_marked(const struct xarray *xa, xa_mark_t mark)
|
|
|
|
{
|
|
|
|
return xa->xa_flags & XA_FLAGS_MARK(mark);
|
|
|
|
}
|
|
|
|
|
2017-11-10 13:15:08 -07:00
|
|
|
/**
|
|
|
|
* xa_erase() - Erase this entry from the XArray.
|
|
|
|
* @xa: XArray.
|
|
|
|
* @index: Index of entry.
|
|
|
|
*
|
|
|
|
* This function is the equivalent of calling xa_store() with %NULL as
|
|
|
|
* the third argument. The XArray does not need to allocate memory, so
|
|
|
|
* the user does not need to provide GFP flags.
|
|
|
|
*
|
|
|
|
* Context: Process context. Takes and releases the xa_lock.
|
|
|
|
* Return: The entry which used to be at this index.
|
|
|
|
*/
|
|
|
|
static inline void *xa_erase(struct xarray *xa, unsigned long index)
|
|
|
|
{
|
|
|
|
return xa_store(xa, index, NULL, 0);
|
|
|
|
}
|
|
|
|
|
2017-11-10 13:34:55 -07:00
|
|
|
/**
|
|
|
|
* 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.
|
|
|
|
*
|
|
|
|
* If you would rather see the existing entry in the array, use xa_cmpxchg().
|
|
|
|
* This function is for users who don't care what the entry is, only that
|
|
|
|
* one is present.
|
|
|
|
*
|
|
|
|
* Context: Process context. Takes and releases the xa_lock.
|
|
|
|
* May sleep if the @gfp flags permit.
|
|
|
|
* Return: 0 if the store succeeded. -EEXIST if another entry was present.
|
|
|
|
* -ENOMEM if memory could not be allocated.
|
|
|
|
*/
|
|
|
|
static inline int xa_insert(struct xarray *xa, unsigned long index,
|
|
|
|
void *entry, gfp_t gfp)
|
|
|
|
{
|
|
|
|
void *curr = xa_cmpxchg(xa, index, NULL, entry, gfp);
|
|
|
|
if (!curr)
|
|
|
|
return 0;
|
|
|
|
if (xa_is_err(curr))
|
|
|
|
return xa_err(curr);
|
|
|
|
return -EEXIST;
|
|
|
|
}
|
|
|
|
|
2018-04-10 17:36:52 -06:00
|
|
|
#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)
|
|
|
|
|
2017-11-10 07:34:31 -07:00
|
|
|
/*
|
2017-11-10 13:15:08 -07:00
|
|
|
* 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);
|
2017-11-10 13:34:55 -07:00
|
|
|
void *__xa_cmpxchg(struct xarray *, unsigned long index, void *old,
|
|
|
|
void *entry, gfp_t);
|
2017-11-10 07:34:31 -07:00
|
|
|
void __xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
|
|
|
|
void __xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
|
|
|
|
|
2017-11-10 13:34:55 -07:00
|
|
|
/**
|
|
|
|
* __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.
|
|
|
|
*
|
|
|
|
* If you would rather see the existing entry in the array, use __xa_cmpxchg().
|
|
|
|
* This function is for users who don't care what the entry is, only that
|
|
|
|
* one is present.
|
|
|
|
*
|
|
|
|
* Context: Any context. Expects xa_lock to be held on entry. May
|
|
|
|
* release and reacquire xa_lock if the @gfp flags permit.
|
|
|
|
* Return: 0 if the store succeeded. -EEXIST if another entry was present.
|
|
|
|
* -ENOMEM if memory could not be allocated.
|
|
|
|
*/
|
|
|
|
static inline int __xa_insert(struct xarray *xa, unsigned long index,
|
|
|
|
void *entry, gfp_t gfp)
|
|
|
|
{
|
|
|
|
void *curr = __xa_cmpxchg(xa, index, NULL, entry, gfp);
|
|
|
|
if (!curr)
|
|
|
|
return 0;
|
|
|
|
if (xa_is_err(curr))
|
|
|
|
return xa_err(curr);
|
|
|
|
return -EEXIST;
|
|
|
|
}
|
|
|
|
|
2017-11-10 13:15:08 -07:00
|
|
|
/**
|
|
|
|
* xa_erase_bh() - Erase this entry from the XArray.
|
|
|
|
* @xa: XArray.
|
|
|
|
* @index: Index of entry.
|
|
|
|
*
|
|
|
|
* This function is the equivalent of calling xa_store() with %NULL as
|
|
|
|
* the third argument. The XArray does not need to allocate memory, so
|
|
|
|
* the user does not need to provide GFP flags.
|
|
|
|
*
|
|
|
|
* Context: Process 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.
|
|
|
|
*
|
|
|
|
* This function is the equivalent of calling xa_store() with %NULL as
|
|
|
|
* the third argument. The XArray does not need to allocate memory, so
|
|
|
|
* the user does not need to provide GFP flags.
|
|
|
|
*
|
|
|
|
* 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;
|
|
|
|
}
|
|
|
|
|
2017-11-03 21:09:45 -06:00
|
|
|
/* 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)
|
2017-11-09 07:23:56 -07:00
|
|
|
#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];
|
|
|
|
};
|
|
|
|
};
|
2017-11-03 21:09:45 -06:00
|
|
|
|
2017-11-07 12:57:46 -07:00
|
|
|
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));
|
|
|
|
}
|
|
|
|
|
2017-11-10 07:34:31 -07:00
|
|
|
/* 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));
|
|
|
|
}
|
|
|
|
|
2017-11-10 13:15:08 -07:00
|
|
|
/* Private */
|
|
|
|
static inline void *xa_mk_node(const struct xa_node *node)
|
|
|
|
{
|
|
|
|
return (void *)((unsigned long)node | 2);
|
|
|
|
}
|
|
|
|
|
2017-11-07 12:57:46 -07:00
|
|
|
/* Private */
|
|
|
|
static inline struct xa_node *xa_to_node(const void *entry)
|
|
|
|
{
|
|
|
|
return (struct xa_node *)((unsigned long)entry - 2);
|
|
|
|
}
|
|
|
|
|
2017-11-03 21:09:45 -06:00
|
|
|
/* 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)
|
|
|
|
|
2017-11-07 12:57:46 -07:00
|
|
|
/**
|
|
|
|
* 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);
|
|
|
|
}
|
|
|
|
|
|
|
|
/**
|
|
|
|
* 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);
|
|
|
|
}
|
|
|
|
|
2017-11-10 07:34:31 -07:00
|
|
|
/* 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;
|
|
|
|
}
|
|
|
|
|
2017-11-10 13:15:08 -07:00
|
|
|
/* True if the node represents head-of-tree, RESTART or BOUNDS */
|
|
|
|
static inline bool xas_top(struct xa_node *node)
|
|
|
|
{
|
|
|
|
return node <= XAS_RESTART;
|
|
|
|
}
|
|
|
|
|
2017-11-07 12:57:46 -07:00
|
|
|
/**
|
|
|
|
* 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_retry(entry))
|
|
|
|
return false;
|
|
|
|
xas_reset(xas);
|
|
|
|
return true;
|
|
|
|
}
|
|
|
|
|
|
|
|
void *xas_load(struct xa_state *);
|
2017-11-10 13:15:08 -07:00
|
|
|
void *xas_store(struct xa_state *, void *entry);
|
2017-11-07 12:57:46 -07:00
|
|
|
|
2017-11-10 07:34:31 -07:00
|
|
|
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);
|
2017-11-10 13:15:08 -07:00
|
|
|
void xas_init_marks(const struct xa_state *);
|
|
|
|
|
|
|
|
bool xas_nomem(struct xa_state *, gfp_t);
|
2017-11-10 07:34:31 -07:00
|
|
|
|
2017-11-07 12:57:46 -07:00
|
|
|
/**
|
|
|
|
* 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);
|
|
|
|
}
|
|
|
|
|
2017-11-10 13:15:08 -07:00
|
|
|
/**
|
|
|
|
* 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;
|
|
|
|
}
|
|
|
|
|
2018-04-10 17:36:52 -06:00
|
|
|
#endif /* _LINUX_XARRAY_H */
|