/* * 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/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 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); int idr_alloc(struct idr *idp, void *ptr, int start, int end, gfp_t gfp_mask); 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_remove(struct idr *idp, 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__ */