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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * 2002-10-18 written by Jim Houston jim.houston@ccur.com
3 * Copyright (C) 2002 by Concurrent Computer Corporation
4 * Distributed under the GNU GPL license version 2.
5 *
6 * Modified by George Anzinger to reuse immediately and to use
7 * find bit instructions. Also removed _irq on spinlocks.
8 *
Nadia Derbey3219b3b2008-07-25 01:48:00 -07009 * Modified by Nadia Derbey to make it RCU safe.
10 *
Jesper Juhle15ae2d2005-10-30 15:02:14 -080011 * Small id to pointer translation service.
Linus Torvalds1da177e2005-04-16 15:20:36 -070012 *
Jesper Juhle15ae2d2005-10-30 15:02:14 -080013 * It uses a radix tree like structure as a sparse array indexed
Linus Torvalds1da177e2005-04-16 15:20:36 -070014 * by the id to obtain the pointer. The bitmap makes allocating
Jesper Juhle15ae2d2005-10-30 15:02:14 -080015 * a new id quick.
Linus Torvalds1da177e2005-04-16 15:20:36 -070016 *
17 * You call it to allocate an id (an int) an associate with that id a
18 * pointer or what ever, we treat it as a (void *). You can pass this
19 * id to a user for him to pass back at a later time. You then pass
20 * that id to this code and it returns your pointer.
21
Jesper Juhle15ae2d2005-10-30 15:02:14 -080022 * You can release ids at any time. When all ids are released, most of
Linus Torvalds1da177e2005-04-16 15:20:36 -070023 * the memory is returned (we keep IDR_FREE_MAX) in a local pool so we
Jesper Juhle15ae2d2005-10-30 15:02:14 -080024 * don't need to go to the memory "store" during an id allocate, just
Linus Torvalds1da177e2005-04-16 15:20:36 -070025 * so you don't need to be too concerned about locking and conflicts
26 * with the slab allocator.
27 */
28
29#ifndef TEST // to test in user space...
30#include <linux/slab.h>
31#include <linux/init.h>
32#include <linux/module.h>
33#endif
Jeff Mahoney5806f072006-06-26 00:27:19 -070034#include <linux/err.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035#include <linux/string.h>
36#include <linux/idr.h>
Rusty Russell88eca022011-08-03 16:21:06 -070037#include <linux/spinlock.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070038
Christoph Lametere18b8902006-12-06 20:33:20 -080039static struct kmem_cache *idr_layer_cache;
Rusty Russell88eca022011-08-03 16:21:06 -070040static DEFINE_SPINLOCK(simple_ida_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070041
Nadia Derbey4ae53782008-07-25 01:47:58 -070042static struct idr_layer *get_from_free_list(struct idr *idp)
Linus Torvalds1da177e2005-04-16 15:20:36 -070043{
44 struct idr_layer *p;
Roland Dreierc259cc22006-07-14 00:24:23 -070045 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -070046
Roland Dreierc259cc22006-07-14 00:24:23 -070047 spin_lock_irqsave(&idp->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -070048 if ((p = idp->id_free)) {
49 idp->id_free = p->ary[0];
50 idp->id_free_cnt--;
51 p->ary[0] = NULL;
52 }
Roland Dreierc259cc22006-07-14 00:24:23 -070053 spin_unlock_irqrestore(&idp->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -070054 return(p);
55}
56
Nadia Derbeycf481c22008-07-25 01:48:02 -070057static void idr_layer_rcu_free(struct rcu_head *head)
58{
59 struct idr_layer *layer;
60
61 layer = container_of(head, struct idr_layer, rcu_head);
62 kmem_cache_free(idr_layer_cache, layer);
63}
64
65static inline void free_layer(struct idr_layer *p)
66{
67 call_rcu(&p->rcu_head, idr_layer_rcu_free);
68}
69
Sonny Rao1eec0052006-06-25 05:49:34 -070070/* only called when idp->lock is held */
Nadia Derbey4ae53782008-07-25 01:47:58 -070071static void __move_to_free_list(struct idr *idp, struct idr_layer *p)
Sonny Rao1eec0052006-06-25 05:49:34 -070072{
73 p->ary[0] = idp->id_free;
74 idp->id_free = p;
75 idp->id_free_cnt++;
76}
77
Nadia Derbey4ae53782008-07-25 01:47:58 -070078static void move_to_free_list(struct idr *idp, struct idr_layer *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -070079{
Roland Dreierc259cc22006-07-14 00:24:23 -070080 unsigned long flags;
81
Linus Torvalds1da177e2005-04-16 15:20:36 -070082 /*
83 * Depends on the return element being zeroed.
84 */
Roland Dreierc259cc22006-07-14 00:24:23 -070085 spin_lock_irqsave(&idp->lock, flags);
Nadia Derbey4ae53782008-07-25 01:47:58 -070086 __move_to_free_list(idp, p);
Roland Dreierc259cc22006-07-14 00:24:23 -070087 spin_unlock_irqrestore(&idp->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -070088}
89
Tejun Heoe33ac8b2007-06-14 03:45:12 +090090static void idr_mark_full(struct idr_layer **pa, int id)
91{
92 struct idr_layer *p = pa[0];
93 int l = 0;
94
95 __set_bit(id & IDR_MASK, &p->bitmap);
96 /*
97 * If this layer is full mark the bit in the layer above to
98 * show that this part of the radix tree is full. This may
99 * complete the layer above and require walking up the radix
100 * tree.
101 */
102 while (p->bitmap == IDR_FULL) {
103 if (!(p = pa[++l]))
104 break;
105 id = id >> IDR_BITS;
106 __set_bit((id & IDR_MASK), &p->bitmap);
107 }
108}
109
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110/**
Randy Dunlap56083ab2010-10-26 14:19:08 -0700111 * idr_pre_get - reserve resources for idr allocation
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112 * @idp: idr handle
113 * @gfp_mask: memory allocation flags
114 *
Naohiro Aota066a9be2010-10-26 14:23:03 -0700115 * This function should be called prior to calling the idr_get_new* functions.
116 * It preallocates enough memory to satisfy the worst possible allocation. The
117 * caller should pass in GFP_KERNEL if possible. This of course requires that
118 * no spinning locks be held.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700120 * If the system is REALLY out of memory this function returns %0,
121 * otherwise %1.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122 */
Al Virofd4f2df2005-10-21 03:18:50 -0400123int idr_pre_get(struct idr *idp, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124{
125 while (idp->id_free_cnt < IDR_FREE_MAX) {
126 struct idr_layer *new;
Andrew Morton5b019e92009-01-15 13:51:21 -0800127 new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800128 if (new == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129 return (0);
Nadia Derbey4ae53782008-07-25 01:47:58 -0700130 move_to_free_list(idp, new);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131 }
132 return 1;
133}
134EXPORT_SYMBOL(idr_pre_get);
135
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900136static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137{
138 int n, m, sh;
139 struct idr_layer *p, *new;
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900140 int l, id, oid;
Al Viro5ba25332007-10-14 19:35:50 +0100141 unsigned long bm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142
143 id = *starting_id;
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900144 restart:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145 p = idp->top;
146 l = idp->layers;
147 pa[l--] = NULL;
148 while (1) {
149 /*
150 * We run around this while until we reach the leaf node...
151 */
152 n = (id >> (IDR_BITS*l)) & IDR_MASK;
153 bm = ~p->bitmap;
154 m = find_next_bit(&bm, IDR_SIZE, n);
155 if (m == IDR_SIZE) {
156 /* no space available go back to previous layer. */
157 l++;
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900158 oid = id;
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800159 id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1;
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900160
161 /* if already at the top layer, we need to grow */
Tejun Heod2e72762010-02-22 12:44:19 -0800162 if (id >= 1 << (idp->layers * IDR_BITS)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 *starting_id = id;
Nadia Derbey944ca052008-07-25 01:47:59 -0700164 return IDR_NEED_TO_GROW;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165 }
Tejun Heod2e72762010-02-22 12:44:19 -0800166 p = pa[l];
167 BUG_ON(!p);
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900168
169 /* If we need to go up one layer, continue the
170 * loop; otherwise, restart from the top.
171 */
172 sh = IDR_BITS * (l + 1);
173 if (oid >> sh == id >> sh)
174 continue;
175 else
176 goto restart;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177 }
178 if (m != n) {
179 sh = IDR_BITS*l;
180 id = ((id >> sh) ^ n ^ m) << sh;
181 }
182 if ((id >= MAX_ID_BIT) || (id < 0))
Nadia Derbey944ca052008-07-25 01:47:59 -0700183 return IDR_NOMORE_SPACE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184 if (l == 0)
185 break;
186 /*
187 * Create the layer below if it is missing.
188 */
189 if (!p->ary[m]) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700190 new = get_from_free_list(idp);
191 if (!new)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192 return -1;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800193 new->layer = l-1;
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700194 rcu_assign_pointer(p->ary[m], new);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195 p->count++;
196 }
197 pa[l--] = p;
198 p = p->ary[m];
199 }
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900200
201 pa[l] = p;
202 return id;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203}
204
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900205static int idr_get_empty_slot(struct idr *idp, int starting_id,
206 struct idr_layer **pa)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207{
208 struct idr_layer *p, *new;
209 int layers, v, id;
Roland Dreierc259cc22006-07-14 00:24:23 -0700210 unsigned long flags;
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800211
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212 id = starting_id;
213build_up:
214 p = idp->top;
215 layers = idp->layers;
216 if (unlikely(!p)) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700217 if (!(p = get_from_free_list(idp)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218 return -1;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800219 p->layer = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220 layers = 1;
221 }
222 /*
223 * Add a new layer to the top of the tree if the requested
224 * id is larger than the currently allocated space.
225 */
Zaur Kambarov589777e2005-06-21 17:14:31 -0700226 while ((layers < (MAX_LEVEL - 1)) && (id >= (1 << (layers*IDR_BITS)))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227 layers++;
Manfred Spraul711a49a2008-12-10 18:17:06 +0100228 if (!p->count) {
229 /* special case: if the tree is currently empty,
230 * then we grow the tree by moving the top node
231 * upwards.
232 */
233 p->layer++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234 continue;
Manfred Spraul711a49a2008-12-10 18:17:06 +0100235 }
Nadia Derbey4ae53782008-07-25 01:47:58 -0700236 if (!(new = get_from_free_list(idp))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237 /*
238 * The allocation failed. If we built part of
239 * the structure tear it down.
240 */
Roland Dreierc259cc22006-07-14 00:24:23 -0700241 spin_lock_irqsave(&idp->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242 for (new = p; p && p != idp->top; new = p) {
243 p = p->ary[0];
244 new->ary[0] = NULL;
245 new->bitmap = new->count = 0;
Nadia Derbey4ae53782008-07-25 01:47:58 -0700246 __move_to_free_list(idp, new);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 }
Roland Dreierc259cc22006-07-14 00:24:23 -0700248 spin_unlock_irqrestore(&idp->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249 return -1;
250 }
251 new->ary[0] = p;
252 new->count = 1;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800253 new->layer = layers-1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254 if (p->bitmap == IDR_FULL)
255 __set_bit(0, &new->bitmap);
256 p = new;
257 }
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700258 rcu_assign_pointer(idp->top, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259 idp->layers = layers;
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900260 v = sub_alloc(idp, &id, pa);
Nadia Derbey944ca052008-07-25 01:47:59 -0700261 if (v == IDR_NEED_TO_GROW)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 goto build_up;
263 return(v);
264}
265
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900266static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id)
267{
268 struct idr_layer *pa[MAX_LEVEL];
269 int id;
270
271 id = idr_get_empty_slot(idp, starting_id, pa);
272 if (id >= 0) {
273 /*
274 * Successfully found an empty slot. Install the user
275 * pointer and mark the slot full.
276 */
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700277 rcu_assign_pointer(pa[0]->ary[id & IDR_MASK],
278 (struct idr_layer *)ptr);
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900279 pa[0]->count++;
280 idr_mark_full(pa, id);
281 }
282
283 return id;
284}
285
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286/**
John McCutchan7c657f22005-08-26 14:02:04 -0400287 * idr_get_new_above - allocate new idr entry above or equal to a start id
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288 * @idp: idr handle
Thadeu Lima de Souza Cascardo94e2bd62009-10-16 15:20:49 +0200289 * @ptr: pointer you want associated with the id
Naohiro Aotaea24ea82010-08-31 00:37:03 +0900290 * @starting_id: id to start search at
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291 * @id: pointer to the allocated handle
292 *
293 * This is the allocate id function. It should be called with any
294 * required locks.
295 *
Naohiro Aota066a9be2010-10-26 14:23:03 -0700296 * If allocation from IDR's private freelist fails, idr_get_new_above() will
Randy Dunlap56083ab2010-10-26 14:19:08 -0700297 * return %-EAGAIN. The caller should retry the idr_pre_get() call to refill
Naohiro Aota066a9be2010-10-26 14:23:03 -0700298 * IDR's preallocation and then retry the idr_get_new_above() call.
299 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700300 * If the idr is full idr_get_new_above() will return %-ENOSPC.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700302 * @id returns a value in the range @starting_id ... %0x7fffffff
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 */
304int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id)
305{
306 int rv;
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800307
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308 rv = idr_get_new_above_int(idp, ptr, starting_id);
309 /*
310 * This is a cheap hack until the IDR code can be fixed to
311 * return proper error values.
312 */
Nadia Derbey944ca052008-07-25 01:47:59 -0700313 if (rv < 0)
314 return _idr_rc_to_errno(rv);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315 *id = rv;
316 return 0;
317}
318EXPORT_SYMBOL(idr_get_new_above);
319
320/**
321 * idr_get_new - allocate new idr entry
322 * @idp: idr handle
Thadeu Lima de Souza Cascardo94e2bd62009-10-16 15:20:49 +0200323 * @ptr: pointer you want associated with the id
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324 * @id: pointer to the allocated handle
325 *
Naohiro Aota066a9be2010-10-26 14:23:03 -0700326 * If allocation from IDR's private freelist fails, idr_get_new_above() will
Randy Dunlap56083ab2010-10-26 14:19:08 -0700327 * return %-EAGAIN. The caller should retry the idr_pre_get() call to refill
Naohiro Aota066a9be2010-10-26 14:23:03 -0700328 * IDR's preallocation and then retry the idr_get_new_above() call.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700330 * If the idr is full idr_get_new_above() will return %-ENOSPC.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700332 * @id returns a value in the range %0 ... %0x7fffffff
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 */
334int idr_get_new(struct idr *idp, void *ptr, int *id)
335{
336 int rv;
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800337
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338 rv = idr_get_new_above_int(idp, ptr, 0);
339 /*
340 * This is a cheap hack until the IDR code can be fixed to
341 * return proper error values.
342 */
Nadia Derbey944ca052008-07-25 01:47:59 -0700343 if (rv < 0)
344 return _idr_rc_to_errno(rv);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345 *id = rv;
346 return 0;
347}
348EXPORT_SYMBOL(idr_get_new);
349
350static void idr_remove_warning(int id)
351{
Nadia Derbeyf098ad62008-07-25 01:47:59 -0700352 printk(KERN_WARNING
353 "idr_remove called for id=%d which is not allocated.\n", id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354 dump_stack();
355}
356
357static void sub_remove(struct idr *idp, int shift, int id)
358{
359 struct idr_layer *p = idp->top;
360 struct idr_layer **pa[MAX_LEVEL];
361 struct idr_layer ***paa = &pa[0];
Nadia Derbeycf481c22008-07-25 01:48:02 -0700362 struct idr_layer *to_free;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 int n;
364
365 *paa = NULL;
366 *++paa = &idp->top;
367
368 while ((shift > 0) && p) {
369 n = (id >> shift) & IDR_MASK;
370 __clear_bit(n, &p->bitmap);
371 *++paa = &p->ary[n];
372 p = p->ary[n];
373 shift -= IDR_BITS;
374 }
375 n = id & IDR_MASK;
376 if (likely(p != NULL && test_bit(n, &p->bitmap))){
377 __clear_bit(n, &p->bitmap);
Nadia Derbeycf481c22008-07-25 01:48:02 -0700378 rcu_assign_pointer(p->ary[n], NULL);
379 to_free = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380 while(*paa && ! --((**paa)->count)){
Nadia Derbeycf481c22008-07-25 01:48:02 -0700381 if (to_free)
382 free_layer(to_free);
383 to_free = **paa;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384 **paa-- = NULL;
385 }
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800386 if (!*paa)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387 idp->layers = 0;
Nadia Derbeycf481c22008-07-25 01:48:02 -0700388 if (to_free)
389 free_layer(to_free);
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800390 } else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391 idr_remove_warning(id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392}
393
394/**
Randy Dunlap56083ab2010-10-26 14:19:08 -0700395 * idr_remove - remove the given id and free its slot
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800396 * @idp: idr handle
397 * @id: unique key
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398 */
399void idr_remove(struct idr *idp, int id)
400{
401 struct idr_layer *p;
Nadia Derbeycf481c22008-07-25 01:48:02 -0700402 struct idr_layer *to_free;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403
404 /* Mask off upper bits we don't use for the search. */
405 id &= MAX_ID_MASK;
406
407 sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800408 if (idp->top && idp->top->count == 1 && (idp->layers > 1) &&
Nadia Derbeycf481c22008-07-25 01:48:02 -0700409 idp->top->ary[0]) {
410 /*
411 * Single child at leftmost slot: we can shrink the tree.
412 * This level is not needed anymore since when layers are
413 * inserted, they are inserted at the top of the existing
414 * tree.
415 */
416 to_free = idp->top;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 p = idp->top->ary[0];
Nadia Derbeycf481c22008-07-25 01:48:02 -0700418 rcu_assign_pointer(idp->top, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419 --idp->layers;
Nadia Derbeycf481c22008-07-25 01:48:02 -0700420 to_free->bitmap = to_free->count = 0;
421 free_layer(to_free);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422 }
423 while (idp->id_free_cnt >= IDR_FREE_MAX) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700424 p = get_from_free_list(idp);
Nadia Derbeycf481c22008-07-25 01:48:02 -0700425 /*
426 * Note: we don't call the rcu callback here, since the only
427 * layers that fall into the freelist are those that have been
428 * preallocated.
429 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430 kmem_cache_free(idr_layer_cache, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 }
Nadia Derbeyaf8e2a42008-05-01 04:34:57 -0700432 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700433}
434EXPORT_SYMBOL(idr_remove);
435
436/**
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700437 * idr_remove_all - remove all ids from the given idr tree
438 * @idp: idr handle
439 *
440 * idr_destroy() only frees up unused, cached idp_layers, but this
441 * function will remove all id mappings and leave all idp_layers
442 * unused.
443 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700444 * A typical clean-up sequence for objects stored in an idr tree will
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700445 * use idr_for_each() to free all objects, if necessay, then
446 * idr_remove_all() to remove all ids, and idr_destroy() to free
447 * up the cached idr_layers.
448 */
449void idr_remove_all(struct idr *idp)
450{
Oleg Nesterov6ace06d2007-07-31 00:39:19 -0700451 int n, id, max;
Imre Deak2dcb22b2010-05-26 14:43:38 -0700452 int bt_mask;
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700453 struct idr_layer *p;
454 struct idr_layer *pa[MAX_LEVEL];
455 struct idr_layer **paa = &pa[0];
456
457 n = idp->layers * IDR_BITS;
458 p = idp->top;
Paul E. McKenney1b233362009-03-10 12:55:52 -0700459 rcu_assign_pointer(idp->top, NULL);
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700460 max = 1 << n;
461
462 id = 0;
Oleg Nesterov6ace06d2007-07-31 00:39:19 -0700463 while (id < max) {
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700464 while (n > IDR_BITS && p) {
465 n -= IDR_BITS;
466 *paa++ = p;
467 p = p->ary[(id >> n) & IDR_MASK];
468 }
469
Imre Deak2dcb22b2010-05-26 14:43:38 -0700470 bt_mask = id;
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700471 id += 1 << n;
Imre Deak2dcb22b2010-05-26 14:43:38 -0700472 /* Get the highest bit that the above add changed from 0->1. */
473 while (n < fls(id ^ bt_mask)) {
Nadia Derbeycf481c22008-07-25 01:48:02 -0700474 if (p)
475 free_layer(p);
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700476 n += IDR_BITS;
477 p = *--paa;
478 }
479 }
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700480 idp->layers = 0;
481}
482EXPORT_SYMBOL(idr_remove_all);
483
484/**
Andrew Morton8d3b3592005-10-23 12:57:18 -0700485 * idr_destroy - release all cached layers within an idr tree
Naohiro Aotaea24ea82010-08-31 00:37:03 +0900486 * @idp: idr handle
Andrew Morton8d3b3592005-10-23 12:57:18 -0700487 */
488void idr_destroy(struct idr *idp)
489{
490 while (idp->id_free_cnt) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700491 struct idr_layer *p = get_from_free_list(idp);
Andrew Morton8d3b3592005-10-23 12:57:18 -0700492 kmem_cache_free(idr_layer_cache, p);
493 }
494}
495EXPORT_SYMBOL(idr_destroy);
496
497/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498 * idr_find - return pointer for given id
499 * @idp: idr handle
500 * @id: lookup key
501 *
502 * Return the pointer given the id it has been registered with. A %NULL
503 * return indicates that @id is not valid or you passed %NULL in
504 * idr_get_new().
505 *
Nadia Derbeyf9c46d62008-07-25 01:48:01 -0700506 * This function can be called under rcu_read_lock(), given that the leaf
507 * pointers lifetimes are correctly managed.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508 */
509void *idr_find(struct idr *idp, int id)
510{
511 int n;
512 struct idr_layer *p;
513
Paul E. McKenney96be7532010-02-22 17:04:55 -0800514 p = rcu_dereference_raw(idp->top);
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800515 if (!p)
516 return NULL;
517 n = (p->layer+1) * IDR_BITS;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518
519 /* Mask off upper bits we don't use for the search. */
520 id &= MAX_ID_MASK;
521
522 if (id >= (1 << n))
523 return NULL;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800524 BUG_ON(n == 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525
526 while (n > 0 && p) {
527 n -= IDR_BITS;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800528 BUG_ON(n != p->layer*IDR_BITS);
Paul E. McKenney96be7532010-02-22 17:04:55 -0800529 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530 }
531 return((void *)p);
532}
533EXPORT_SYMBOL(idr_find);
534
Jeff Mahoney5806f072006-06-26 00:27:19 -0700535/**
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700536 * idr_for_each - iterate through all stored pointers
537 * @idp: idr handle
538 * @fn: function to be called for each pointer
539 * @data: data passed back to callback function
540 *
541 * Iterate over the pointers registered with the given idr. The
542 * callback function will be called for each pointer currently
543 * registered, passing the id, the pointer and the data pointer passed
544 * to this function. It is not safe to modify the idr tree while in
545 * the callback, so functions such as idr_get_new and idr_remove are
546 * not allowed.
547 *
548 * We check the return of @fn each time. If it returns anything other
Randy Dunlap56083ab2010-10-26 14:19:08 -0700549 * than %0, we break out and return that value.
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700550 *
551 * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove().
552 */
553int idr_for_each(struct idr *idp,
554 int (*fn)(int id, void *p, void *data), void *data)
555{
556 int n, id, max, error = 0;
557 struct idr_layer *p;
558 struct idr_layer *pa[MAX_LEVEL];
559 struct idr_layer **paa = &pa[0];
560
561 n = idp->layers * IDR_BITS;
Paul E. McKenney96be7532010-02-22 17:04:55 -0800562 p = rcu_dereference_raw(idp->top);
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700563 max = 1 << n;
564
565 id = 0;
566 while (id < max) {
567 while (n > 0 && p) {
568 n -= IDR_BITS;
569 *paa++ = p;
Paul E. McKenney96be7532010-02-22 17:04:55 -0800570 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700571 }
572
573 if (p) {
574 error = fn(id, (void *)p, data);
575 if (error)
576 break;
577 }
578
579 id += 1 << n;
580 while (n < fls(id)) {
581 n += IDR_BITS;
582 p = *--paa;
583 }
584 }
585
586 return error;
587}
588EXPORT_SYMBOL(idr_for_each);
589
590/**
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700591 * idr_get_next - lookup next object of id to given id.
592 * @idp: idr handle
Naohiro Aotaea24ea82010-08-31 00:37:03 +0900593 * @nextidp: pointer to lookup key
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700594 *
595 * Returns pointer to registered object with id, which is next number to
Naohiro Aota1458ce12010-08-27 17:43:46 +0900596 * given id. After being looked up, *@nextidp will be updated for the next
597 * iteration.
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700598 */
599
600void *idr_get_next(struct idr *idp, int *nextidp)
601{
602 struct idr_layer *p, *pa[MAX_LEVEL];
603 struct idr_layer **paa = &pa[0];
604 int id = *nextidp;
605 int n, max;
606
607 /* find first ent */
608 n = idp->layers * IDR_BITS;
609 max = 1 << n;
Paul E. McKenney94bfa3b2010-06-07 17:09:45 -0700610 p = rcu_dereference_raw(idp->top);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700611 if (!p)
612 return NULL;
613
614 while (id < max) {
615 while (n > 0 && p) {
616 n -= IDR_BITS;
617 *paa++ = p;
Paul E. McKenney94bfa3b2010-06-07 17:09:45 -0700618 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700619 }
620
621 if (p) {
622 *nextidp = id;
623 return p;
624 }
625
626 id += 1 << n;
627 while (n < fls(id)) {
628 n += IDR_BITS;
629 p = *--paa;
630 }
631 }
632 return NULL;
633}
Ben Hutchings4d1ee802010-01-29 20:59:17 +0000634EXPORT_SYMBOL(idr_get_next);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700635
636
637/**
Jeff Mahoney5806f072006-06-26 00:27:19 -0700638 * idr_replace - replace pointer for given id
639 * @idp: idr handle
640 * @ptr: pointer you want associated with the id
641 * @id: lookup key
642 *
643 * Replace the pointer registered with an id and return the old value.
Randy Dunlap56083ab2010-10-26 14:19:08 -0700644 * A %-ENOENT return indicates that @id was not found.
645 * A %-EINVAL return indicates that @id was not within valid constraints.
Jeff Mahoney5806f072006-06-26 00:27:19 -0700646 *
Nadia Derbeycf481c22008-07-25 01:48:02 -0700647 * The caller must serialize with writers.
Jeff Mahoney5806f072006-06-26 00:27:19 -0700648 */
649void *idr_replace(struct idr *idp, void *ptr, int id)
650{
651 int n;
652 struct idr_layer *p, *old_p;
653
Jeff Mahoney5806f072006-06-26 00:27:19 -0700654 p = idp->top;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800655 if (!p)
656 return ERR_PTR(-EINVAL);
657
658 n = (p->layer+1) * IDR_BITS;
Jeff Mahoney5806f072006-06-26 00:27:19 -0700659
660 id &= MAX_ID_MASK;
661
662 if (id >= (1 << n))
663 return ERR_PTR(-EINVAL);
664
665 n -= IDR_BITS;
666 while ((n > 0) && p) {
667 p = p->ary[(id >> n) & IDR_MASK];
668 n -= IDR_BITS;
669 }
670
671 n = id & IDR_MASK;
672 if (unlikely(p == NULL || !test_bit(n, &p->bitmap)))
673 return ERR_PTR(-ENOENT);
674
675 old_p = p->ary[n];
Nadia Derbeycf481c22008-07-25 01:48:02 -0700676 rcu_assign_pointer(p->ary[n], ptr);
Jeff Mahoney5806f072006-06-26 00:27:19 -0700677
678 return old_p;
679}
680EXPORT_SYMBOL(idr_replace);
681
Akinobu Mita199f0ca2008-04-29 01:03:13 -0700682void __init idr_init_cache(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700683{
Akinobu Mita199f0ca2008-04-29 01:03:13 -0700684 idr_layer_cache = kmem_cache_create("idr_layer_cache",
Andrew Morton5b019e92009-01-15 13:51:21 -0800685 sizeof(struct idr_layer), 0, SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700686}
687
688/**
689 * idr_init - initialize idr handle
690 * @idp: idr handle
691 *
692 * This function is use to set up the handle (@idp) that you will pass
693 * to the rest of the functions.
694 */
695void idr_init(struct idr *idp)
696{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697 memset(idp, 0, sizeof(struct idr));
698 spin_lock_init(&idp->lock);
699}
700EXPORT_SYMBOL(idr_init);
Tejun Heo72dba582007-06-14 03:45:13 +0900701
702
Randy Dunlap56083ab2010-10-26 14:19:08 -0700703/**
704 * DOC: IDA description
Tejun Heo72dba582007-06-14 03:45:13 +0900705 * IDA - IDR based ID allocator
706 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700707 * This is id allocator without id -> pointer translation. Memory
Tejun Heo72dba582007-06-14 03:45:13 +0900708 * usage is much lower than full blown idr because each id only
709 * occupies a bit. ida uses a custom leaf node which contains
710 * IDA_BITMAP_BITS slots.
711 *
712 * 2007-04-25 written by Tejun Heo <htejun@gmail.com>
713 */
714
715static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap)
716{
717 unsigned long flags;
718
719 if (!ida->free_bitmap) {
720 spin_lock_irqsave(&ida->idr.lock, flags);
721 if (!ida->free_bitmap) {
722 ida->free_bitmap = bitmap;
723 bitmap = NULL;
724 }
725 spin_unlock_irqrestore(&ida->idr.lock, flags);
726 }
727
728 kfree(bitmap);
729}
730
731/**
732 * ida_pre_get - reserve resources for ida allocation
733 * @ida: ida handle
734 * @gfp_mask: memory allocation flag
735 *
736 * This function should be called prior to locking and calling the
737 * following function. It preallocates enough memory to satisfy the
738 * worst possible allocation.
739 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700740 * If the system is REALLY out of memory this function returns %0,
741 * otherwise %1.
Tejun Heo72dba582007-06-14 03:45:13 +0900742 */
743int ida_pre_get(struct ida *ida, gfp_t gfp_mask)
744{
745 /* allocate idr_layers */
746 if (!idr_pre_get(&ida->idr, gfp_mask))
747 return 0;
748
749 /* allocate free_bitmap */
750 if (!ida->free_bitmap) {
751 struct ida_bitmap *bitmap;
752
753 bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask);
754 if (!bitmap)
755 return 0;
756
757 free_bitmap(ida, bitmap);
758 }
759
760 return 1;
761}
762EXPORT_SYMBOL(ida_pre_get);
763
764/**
765 * ida_get_new_above - allocate new ID above or equal to a start id
766 * @ida: ida handle
Naohiro Aotaea24ea82010-08-31 00:37:03 +0900767 * @starting_id: id to start search at
Tejun Heo72dba582007-06-14 03:45:13 +0900768 * @p_id: pointer to the allocated handle
769 *
770 * Allocate new ID above or equal to @ida. It should be called with
771 * any required locks.
772 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700773 * If memory is required, it will return %-EAGAIN, you should unlock
Tejun Heo72dba582007-06-14 03:45:13 +0900774 * and go back to the ida_pre_get() call. If the ida is full, it will
Randy Dunlap56083ab2010-10-26 14:19:08 -0700775 * return %-ENOSPC.
Tejun Heo72dba582007-06-14 03:45:13 +0900776 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700777 * @p_id returns a value in the range @starting_id ... %0x7fffffff.
Tejun Heo72dba582007-06-14 03:45:13 +0900778 */
779int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
780{
781 struct idr_layer *pa[MAX_LEVEL];
782 struct ida_bitmap *bitmap;
783 unsigned long flags;
784 int idr_id = starting_id / IDA_BITMAP_BITS;
785 int offset = starting_id % IDA_BITMAP_BITS;
786 int t, id;
787
788 restart:
789 /* get vacant slot */
790 t = idr_get_empty_slot(&ida->idr, idr_id, pa);
Nadia Derbey944ca052008-07-25 01:47:59 -0700791 if (t < 0)
792 return _idr_rc_to_errno(t);
Tejun Heo72dba582007-06-14 03:45:13 +0900793
794 if (t * IDA_BITMAP_BITS >= MAX_ID_BIT)
795 return -ENOSPC;
796
797 if (t != idr_id)
798 offset = 0;
799 idr_id = t;
800
801 /* if bitmap isn't there, create a new one */
802 bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK];
803 if (!bitmap) {
804 spin_lock_irqsave(&ida->idr.lock, flags);
805 bitmap = ida->free_bitmap;
806 ida->free_bitmap = NULL;
807 spin_unlock_irqrestore(&ida->idr.lock, flags);
808
809 if (!bitmap)
810 return -EAGAIN;
811
812 memset(bitmap, 0, sizeof(struct ida_bitmap));
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700813 rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK],
814 (void *)bitmap);
Tejun Heo72dba582007-06-14 03:45:13 +0900815 pa[0]->count++;
816 }
817
818 /* lookup for empty slot */
819 t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset);
820 if (t == IDA_BITMAP_BITS) {
821 /* no empty slot after offset, continue to the next chunk */
822 idr_id++;
823 offset = 0;
824 goto restart;
825 }
826
827 id = idr_id * IDA_BITMAP_BITS + t;
828 if (id >= MAX_ID_BIT)
829 return -ENOSPC;
830
831 __set_bit(t, bitmap->bitmap);
832 if (++bitmap->nr_busy == IDA_BITMAP_BITS)
833 idr_mark_full(pa, idr_id);
834
835 *p_id = id;
836
837 /* Each leaf node can handle nearly a thousand slots and the
838 * whole idea of ida is to have small memory foot print.
839 * Throw away extra resources one by one after each successful
840 * allocation.
841 */
842 if (ida->idr.id_free_cnt || ida->free_bitmap) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700843 struct idr_layer *p = get_from_free_list(&ida->idr);
Tejun Heo72dba582007-06-14 03:45:13 +0900844 if (p)
845 kmem_cache_free(idr_layer_cache, p);
846 }
847
848 return 0;
849}
850EXPORT_SYMBOL(ida_get_new_above);
851
852/**
853 * ida_get_new - allocate new ID
854 * @ida: idr handle
855 * @p_id: pointer to the allocated handle
856 *
857 * Allocate new ID. It should be called with any required locks.
858 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700859 * If memory is required, it will return %-EAGAIN, you should unlock
Tejun Heo72dba582007-06-14 03:45:13 +0900860 * and go back to the idr_pre_get() call. If the idr is full, it will
Randy Dunlap56083ab2010-10-26 14:19:08 -0700861 * return %-ENOSPC.
Tejun Heo72dba582007-06-14 03:45:13 +0900862 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700863 * @id returns a value in the range %0 ... %0x7fffffff.
Tejun Heo72dba582007-06-14 03:45:13 +0900864 */
865int ida_get_new(struct ida *ida, int *p_id)
866{
867 return ida_get_new_above(ida, 0, p_id);
868}
869EXPORT_SYMBOL(ida_get_new);
870
871/**
872 * ida_remove - remove the given ID
873 * @ida: ida handle
874 * @id: ID to free
875 */
876void ida_remove(struct ida *ida, int id)
877{
878 struct idr_layer *p = ida->idr.top;
879 int shift = (ida->idr.layers - 1) * IDR_BITS;
880 int idr_id = id / IDA_BITMAP_BITS;
881 int offset = id % IDA_BITMAP_BITS;
882 int n;
883 struct ida_bitmap *bitmap;
884
885 /* clear full bits while looking up the leaf idr_layer */
886 while ((shift > 0) && p) {
887 n = (idr_id >> shift) & IDR_MASK;
888 __clear_bit(n, &p->bitmap);
889 p = p->ary[n];
890 shift -= IDR_BITS;
891 }
892
893 if (p == NULL)
894 goto err;
895
896 n = idr_id & IDR_MASK;
897 __clear_bit(n, &p->bitmap);
898
899 bitmap = (void *)p->ary[n];
900 if (!test_bit(offset, bitmap->bitmap))
901 goto err;
902
903 /* update bitmap and remove it if empty */
904 __clear_bit(offset, bitmap->bitmap);
905 if (--bitmap->nr_busy == 0) {
906 __set_bit(n, &p->bitmap); /* to please idr_remove() */
907 idr_remove(&ida->idr, idr_id);
908 free_bitmap(ida, bitmap);
909 }
910
911 return;
912
913 err:
914 printk(KERN_WARNING
915 "ida_remove called for id=%d which is not allocated.\n", id);
916}
917EXPORT_SYMBOL(ida_remove);
918
919/**
920 * ida_destroy - release all cached layers within an ida tree
Naohiro Aotaea24ea82010-08-31 00:37:03 +0900921 * @ida: ida handle
Tejun Heo72dba582007-06-14 03:45:13 +0900922 */
923void ida_destroy(struct ida *ida)
924{
925 idr_destroy(&ida->idr);
926 kfree(ida->free_bitmap);
927}
928EXPORT_SYMBOL(ida_destroy);
929
930/**
Rusty Russell88eca022011-08-03 16:21:06 -0700931 * ida_simple_get - get a new id.
932 * @ida: the (initialized) ida.
933 * @start: the minimum id (inclusive, < 0x8000000)
934 * @end: the maximum id (exclusive, < 0x8000000 or 0)
935 * @gfp_mask: memory allocation flags
936 *
937 * Allocates an id in the range start <= id < end, or returns -ENOSPC.
938 * On memory allocation failure, returns -ENOMEM.
939 *
940 * Use ida_simple_remove() to get rid of an id.
941 */
942int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
943 gfp_t gfp_mask)
944{
945 int ret, id;
946 unsigned int max;
947
948 BUG_ON((int)start < 0);
949 BUG_ON((int)end < 0);
950
951 if (end == 0)
952 max = 0x80000000;
953 else {
954 BUG_ON(end < start);
955 max = end - 1;
956 }
957
958again:
959 if (!ida_pre_get(ida, gfp_mask))
960 return -ENOMEM;
961
962 spin_lock(&simple_ida_lock);
963 ret = ida_get_new_above(ida, start, &id);
964 if (!ret) {
965 if (id > max) {
966 ida_remove(ida, id);
967 ret = -ENOSPC;
968 } else {
969 ret = id;
970 }
971 }
972 spin_unlock(&simple_ida_lock);
973
974 if (unlikely(ret == -EAGAIN))
975 goto again;
976
977 return ret;
978}
979EXPORT_SYMBOL(ida_simple_get);
980
981/**
982 * ida_simple_remove - remove an allocated id.
983 * @ida: the (initialized) ida.
984 * @id: the id returned by ida_simple_get.
985 */
986void ida_simple_remove(struct ida *ida, unsigned int id)
987{
988 BUG_ON((int)id < 0);
989 spin_lock(&simple_ida_lock);
990 ida_remove(ida, id);
991 spin_unlock(&simple_ida_lock);
992}
993EXPORT_SYMBOL(ida_simple_remove);
994
995/**
Tejun Heo72dba582007-06-14 03:45:13 +0900996 * ida_init - initialize ida handle
997 * @ida: ida handle
998 *
999 * This function is use to set up the handle (@ida) that you will pass
1000 * to the rest of the functions.
1001 */
1002void ida_init(struct ida *ida)
1003{
1004 memset(ida, 0, sizeof(struct ida));
1005 idr_init(&ida->idr);
1006
1007}
1008EXPORT_SYMBOL(ida_init);