/*
* include/linux/idr.h
*
* 2002-10-18 written by Jim Houston jim.houston@ccur.com
* Copyright (C) 2002 by Concurrent Computer Corporation
* Distributed under the GNU GPL license version 2.
*
* Small id to pointer translation service avoiding fixed sized
* tables.
*/
#ifndef __IDR2_H__
#define __IDR2_H__
#include <linux/types.h>
#include <linux/bitops.h>
#include <linux/init.h>
#include <linux/rcupdate.h>
/*
* We want shallower trees and thus more bits covered at each layer. 8
* bits gives us large enough first layer for most use cases and maximum
* tree depth of 4. Each idr2_layer is slightly larger than 2k on 64bit and
* 1k on 32bit.
*/
#define IDR2_BITS 8
#define IDR2_SIZE (1 << IDR2_BITS)
#define IDR2_MASK ((1 << IDR2_BITS)-1)
struct idr2_layer {
int prefix; /* the ID prefix of this idr2_layer */
int layer; /* distance from leaf */
struct idr2_layer __rcu *ary[1<<IDR2_BITS];
int count; /* When zero, we can release it */
union {
/* A zero bit means "space here" */
DECLARE_BITMAP(bitmap, IDR2_SIZE);
struct rcu_head rcu_head;
};
};
struct idr2 {
struct idr2_layer __rcu *hint; /* the last layer allocated from */
struct idr2_layer __rcu *top;
int layers; /* only valid w/o concurrent changes */
int cur; /* current pos for cyclic allocation */
spinlock_t lock;
int id_free_cnt;
struct idr2_layer *id_free;
};
#define IDR2_INIT(name) \
{ \
.lock = __SPIN_LOCK_UNLOCKED(name.lock), \
}
#define DEFINE_IDR2(name) struct idr2 name = IDR2_INIT(name)
/**
* DOC: idr2 sync
* idr2 synchronization (stolen from radix-tree.h)
*
* idr2_find() is able to be called locklessly, using RCU. The caller must
* ensure calls to this function are made within rcu_read_lock() regions.
* Other readers (lock-free or otherwise) and modifications may be running
* concurrently.
*
* It is still required that the caller manage the synchronization and
* lifetimes of the items. So if RCU lock-free lookups are used, typically
* this would mean that the items have their own locks, or are amenable to
* lock-free access; and that the items are freed by RCU (or only freed after
* having been deleted from the idr2 tree *and* a synchronize_rcu() grace
* period).
*/
/*
* This is what we export.
*/
void *idr2_find_slowpath(struct idr2 *idp, int id);
void idr2_preload(gfp_t gfp_mask);
int idr2_alloc(struct idr2 *idp, void *ptr, int start, int end, gfp_t gfp_mask);
int idr2_alloc_cyclic(struct idr2 *idr2, void *ptr, int start, int end, gfp_t gfp_mask);
int idr2_for_each(struct idr2 *idp,
int (*fn)(int id, void *p, void *data), void *data);
void *idr2_get_next(struct idr2 *idp, int *nextid);
void *idr2_replace(struct idr2 *idp, void *ptr, int id);
void idr2_remove(struct idr2 *idp, int id);
void idr2_destroy(struct idr2 *idp);
void idr2_init(struct idr2 *idp);
bool idr2_is_empty(struct idr2 *idp);
/**
* idr2_preload_end - end preload section started with idr2_preload()
*
* Each idr2_preload() should be matched with an invocation of this
* function. See idr2_preload() for details.
*/
static inline void idr2_preload_end(void)
{
preempt_enable();
}
/**
* idr2_find - return pointer for given id
* @idr2: idr2 handle
* @id: lookup key
*
* Return the pointer given the id it has been registered with. A %NULL
* return indicates that @id is not valid or you passed %NULL in
* idr2_get_new().
*
* This function can be called under rcu_read_lock(), given that the leaf
* pointers lifetimes are correctly managed.
*/
static inline void *idr2_find(struct idr2 *idr2, int id)
{
struct idr2_layer *hint = rcu_dereference_raw(idr2->hint);
if (hint && (id & ~IDR2_MASK) == hint->prefix)
return rcu_dereference_raw(hint->ary[id & IDR2_MASK]);
return idr2_find_slowpath(idr2, id);
}
/**
* idr2_for_each_entry - iterate over an idr2's elements of a given type
* @idp: idr2 handle
* @entry: the type * to use as cursor
* @id: id entry's key
*
* @entry and @id do not need to be initialized before the loop, and
* after normal terminatinon @entry is left with the value NULL. This
* is convenient for a "not found" value.
*/
#define idr2_for_each_entry(idp, entry, id) \
for (id = 0; ((entry) = idr2_get_next(idp, &(id))) != NULL; ++id)
/*
* IDA2 - IDR2 based id allocator, use when translation from id to
* pointer isn't necessary.
*
* IDA2_BITMAP_LONGS is calculated to be one less to accommodate
* ida2_bitmap->nr_busy so that the whole struct fits in 128 bytes.
*/
#define IDA2_CHUNK_SIZE 128 /* 128 bytes per chunk */
#define IDA2_BITMAP_LONGS (IDA2_CHUNK_SIZE / sizeof(long) - 1)
#define IDA2_BITMAP_BITS (IDA2_BITMAP_LONGS * sizeof(long) * 8)
struct ida2_bitmap {
long nr_busy;
unsigned long bitmap[IDA2_BITMAP_LONGS];
};
struct ida2 {
struct idr2 idr2;
struct ida2_bitmap *free_bitmap;
};
#define IDA2_INIT(name) { .idr2 = IDR2_INIT((name).idr2), .free_bitmap = NULL, }
#define DEFINE_IDA2(name) struct ida2 name = IDA2_INIT(name)
int ida2_pre_get(struct ida2 *ida2, gfp_t gfp_mask);
int ida2_get_new_above(struct ida2 *ida2, int starting_id, int *p_id);
void ida2_remove(struct ida2 *ida2, int id);
void ida2_destroy(struct ida2 *ida2);
void ida2_init(struct ida2 *ida2);
int ida2_simple_get(struct ida2 *ida2, unsigned int start, unsigned int end,
gfp_t gfp_mask);
void ida2_simple_remove(struct ida2 *ida2, unsigned int id);
/**
* ida2_get_new - allocate new ID
* @ida2: idr2 handle
* @p_id: pointer to the allocated handle
*
* Simple wrapper around ida2_get_new_above() w/ @starting_id of zero.
*/
static inline int ida2_get_new(struct ida2 *ida2, int *p_id)
{
return ida2_get_new_above(ida2, 0, p_id);
}
void __init idr2_init_cache(void);
#endif /* __IDR2_H__ */
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