+++ /dev/null
-/*
- * 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 __IDR_H__
-#define __IDR_H__
-
-#include <linux/types.h>
-#include <linux/bitmap.h>
-#include <linux/bitops.h>
-#include <linux/preempt.h>
-#include <linux/rcupdate.h>
-#include <linux/spinlock.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 idr_layer is slightly larger than 2k on 64bit and
- * 1k on 32bit.
- */
-#define IDR_BITS 8
-#define IDR_SIZE (1 << IDR_BITS)
-#define IDR_MASK ((1 << IDR_BITS)-1)
-
-struct idr_layer {
- int prefix; /* the ID prefix of this idr_layer */
- int layer; /* distance from leaf */
- struct idr_layer __rcu *ary[1<<IDR_BITS];
- int count; /* When zero, we can release it */
- union {
- /* A zero bit means "space here" */
- DECLARE_BITMAP(bitmap, IDR_SIZE);
- struct rcu_head rcu_head;
- };
-};
-
-struct idr {
- struct idr_layer __rcu *hint; /* the last layer allocated from */
- struct idr_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 idr_layer *id_free;
-};
-
-#define IDR_INIT(name) \
-{ \
- .lock = __SPIN_LOCK_UNLOCKED(name.lock), \
-}
-#define DEFINE_IDR(name) struct idr name = IDR_INIT(name)
-
-/**
- * DOC: idr sync
- * idr synchronization (stolen from radix-tree.h)
- *
- * idr_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 idr tree *and* a synchronize_rcu() grace
- * period).
- */
-
-/*
- * This is what we export.
- */
-
-void *idr_find_slowpath(struct idr *idp, int id);
-void idr_preload(gfp_t gfp_mask);
-
-static inline int idr_alloc(struct idr *idp, void *ptr, int start, int end, gfp_t gfp_mask)
-{
- return 0;
-}
-
-static inline void idr_remove(struct idr *idp, int id) {}
-
-int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask);
-int idr_for_each(struct idr *idp,
- int (*fn)(int id, void *p, void *data), void *data);
-void *idr_get_next(struct idr *idp, int *nextid);
-void *idr_replace(struct idr *idp, void *ptr, int id);
-void idr_destroy(struct idr *idp);
-void idr_init(struct idr *idp);
-bool idr_is_empty(struct idr *idp);
-
-/**
- * idr_preload_end - end preload section started with idr_preload()
- *
- * Each idr_preload() should be matched with an invocation of this
- * function. See idr_preload() for details.
- */
-static inline void idr_preload_end(void)
-{
- preempt_enable();
-}
-
-/**
- * idr_find - return pointer for given id
- * @idr: idr 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
- * idr_get_new().
- *
- * This function can be called under rcu_read_lock(), given that the leaf
- * pointers lifetimes are correctly managed.
- */
-static inline void *idr_find(struct idr *idr, int id)
-{
- struct idr_layer *hint = rcu_dereference_raw(idr->hint);
-
- if (hint && (id & ~IDR_MASK) == hint->prefix)
- return rcu_dereference_raw(hint->ary[id & IDR_MASK]);
-
- return idr_find_slowpath(idr, id);
-}
-
-/**
- * idr_for_each_entry - iterate over an idr's elements of a given type
- * @idp: idr 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 idr_for_each_entry(idp, entry, id) \
- for (id = 0; ((entry) = idr_get_next(idp, &(id))) != NULL; ++id)
-
-/**
- * idr_for_each_entry - continue iteration over an idr's elements of a given type
- * @idp: idr handle
- * @entry: the type * to use as cursor
- * @id: id entry's key
- *
- * Continue to iterate over list of given type, continuing after
- * the current position.
- */
-#define idr_for_each_entry_continue(idp, entry, id) \
- for ((entry) = idr_get_next((idp), &(id)); \
- entry; \
- ++id, (entry) = idr_get_next((idp), &(id)))
-
-/*
- * IDA - IDR based id allocator, use when translation from id to
- * pointer isn't necessary.
- *
- * IDA_BITMAP_LONGS is calculated to be one less to accommodate
- * ida_bitmap->nr_busy so that the whole struct fits in 128 bytes.
- */
-#define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */
-#define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long) - 1)
-#define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8)
-
-struct ida_bitmap {
- long nr_busy;
- unsigned long bitmap[IDA_BITMAP_LONGS];
-};
-
-struct ida {
- struct idr idr;
- struct ida_bitmap *free_bitmap;
-};
-
-#define IDA_INIT(name) { .idr = IDR_INIT((name).idr), .free_bitmap = NULL, }
-#define DEFINE_IDA(name) struct ida name = IDA_INIT(name)
-
-int ida_pre_get(struct ida *ida, gfp_t gfp_mask);
-int ida_get_new_above(struct ida *ida, int starting_id, int *p_id);
-void ida_remove(struct ida *ida, int id);
-void ida_destroy(struct ida *ida);
-void ida_init(struct ida *ida);
-
-int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
- gfp_t gfp_mask);
-void ida_simple_remove(struct ida *ida, unsigned int id);
-
-/**
- * ida_get_new - allocate new ID
- * @ida: idr handle
- * @p_id: pointer to the allocated handle
- *
- * Simple wrapper around ida_get_new_above() w/ @starting_id of zero.
- */
-static inline int ida_get_new(struct ida *ida, int *p_id)
-{
- return ida_get_new_above(ida, 0, p_id);
-}
-
-void __init idr_init_cache(void);
-
-#endif /* __IDR_H__ */
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