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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>
37
Christoph Lametere18b8902006-12-06 20:33:20 -080038static struct kmem_cache *idr_layer_cache;
Linus Torvalds1da177e2005-04-16 15:20:36 -070039
Nadia Derbey4ae53782008-07-25 01:47:58 -070040static struct idr_layer *get_from_free_list(struct idr *idp)
Linus Torvalds1da177e2005-04-16 15:20:36 -070041{
42 struct idr_layer *p;
Roland Dreierc259cc22006-07-14 00:24:23 -070043 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -070044
Roland Dreierc259cc22006-07-14 00:24:23 -070045 spin_lock_irqsave(&idp->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -070046 if ((p = idp->id_free)) {
47 idp->id_free = p->ary[0];
48 idp->id_free_cnt--;
49 p->ary[0] = NULL;
50 }
Roland Dreierc259cc22006-07-14 00:24:23 -070051 spin_unlock_irqrestore(&idp->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 return(p);
53}
54
Nadia Derbeycf481c22008-07-25 01:48:02 -070055static void idr_layer_rcu_free(struct rcu_head *head)
56{
57 struct idr_layer *layer;
58
59 layer = container_of(head, struct idr_layer, rcu_head);
60 kmem_cache_free(idr_layer_cache, layer);
61}
62
63static inline void free_layer(struct idr_layer *p)
64{
65 call_rcu(&p->rcu_head, idr_layer_rcu_free);
66}
67
Sonny Rao1eec0052006-06-25 05:49:34 -070068/* only called when idp->lock is held */
Nadia Derbey4ae53782008-07-25 01:47:58 -070069static void __move_to_free_list(struct idr *idp, struct idr_layer *p)
Sonny Rao1eec0052006-06-25 05:49:34 -070070{
71 p->ary[0] = idp->id_free;
72 idp->id_free = p;
73 idp->id_free_cnt++;
74}
75
Nadia Derbey4ae53782008-07-25 01:47:58 -070076static void move_to_free_list(struct idr *idp, struct idr_layer *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -070077{
Roland Dreierc259cc22006-07-14 00:24:23 -070078 unsigned long flags;
79
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 /*
81 * Depends on the return element being zeroed.
82 */
Roland Dreierc259cc22006-07-14 00:24:23 -070083 spin_lock_irqsave(&idp->lock, flags);
Nadia Derbey4ae53782008-07-25 01:47:58 -070084 __move_to_free_list(idp, p);
Roland Dreierc259cc22006-07-14 00:24:23 -070085 spin_unlock_irqrestore(&idp->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -070086}
87
Tejun Heoe33ac8b2007-06-14 03:45:12 +090088static void idr_mark_full(struct idr_layer **pa, int id)
89{
90 struct idr_layer *p = pa[0];
91 int l = 0;
92
93 __set_bit(id & IDR_MASK, &p->bitmap);
94 /*
95 * If this layer is full mark the bit in the layer above to
96 * show that this part of the radix tree is full. This may
97 * complete the layer above and require walking up the radix
98 * tree.
99 */
100 while (p->bitmap == IDR_FULL) {
101 if (!(p = pa[++l]))
102 break;
103 id = id >> IDR_BITS;
104 __set_bit((id & IDR_MASK), &p->bitmap);
105 }
106}
107
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108/**
Randy Dunlap56083ab2010-10-26 14:19:08 -0700109 * idr_pre_get - reserve resources for idr allocation
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110 * @idp: idr handle
111 * @gfp_mask: memory allocation flags
112 *
Naohiro Aota066a9be2010-10-26 14:23:03 -0700113 * This function should be called prior to calling the idr_get_new* functions.
114 * It preallocates enough memory to satisfy the worst possible allocation. The
115 * caller should pass in GFP_KERNEL if possible. This of course requires that
116 * no spinning locks be held.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700118 * If the system is REALLY out of memory this function returns %0,
119 * otherwise %1.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 */
Al Virofd4f2df2005-10-21 03:18:50 -0400121int idr_pre_get(struct idr *idp, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122{
123 while (idp->id_free_cnt < IDR_FREE_MAX) {
124 struct idr_layer *new;
Andrew Morton5b019e92009-01-15 13:51:21 -0800125 new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800126 if (new == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127 return (0);
Nadia Derbey4ae53782008-07-25 01:47:58 -0700128 move_to_free_list(idp, new);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129 }
130 return 1;
131}
132EXPORT_SYMBOL(idr_pre_get);
133
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900134static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135{
136 int n, m, sh;
137 struct idr_layer *p, *new;
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900138 int l, id, oid;
Al Viro5ba25332007-10-14 19:35:50 +0100139 unsigned long bm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140
141 id = *starting_id;
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900142 restart:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 p = idp->top;
144 l = idp->layers;
145 pa[l--] = NULL;
146 while (1) {
147 /*
148 * We run around this while until we reach the leaf node...
149 */
150 n = (id >> (IDR_BITS*l)) & IDR_MASK;
151 bm = ~p->bitmap;
152 m = find_next_bit(&bm, IDR_SIZE, n);
153 if (m == IDR_SIZE) {
154 /* no space available go back to previous layer. */
155 l++;
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900156 oid = id;
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800157 id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1;
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900158
159 /* if already at the top layer, we need to grow */
Tejun Heod2e72762010-02-22 12:44:19 -0800160 if (id >= 1 << (idp->layers * IDR_BITS)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161 *starting_id = id;
Nadia Derbey944ca052008-07-25 01:47:59 -0700162 return IDR_NEED_TO_GROW;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 }
Tejun Heod2e72762010-02-22 12:44:19 -0800164 p = pa[l];
165 BUG_ON(!p);
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900166
167 /* If we need to go up one layer, continue the
168 * loop; otherwise, restart from the top.
169 */
170 sh = IDR_BITS * (l + 1);
171 if (oid >> sh == id >> sh)
172 continue;
173 else
174 goto restart;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 }
176 if (m != n) {
177 sh = IDR_BITS*l;
178 id = ((id >> sh) ^ n ^ m) << sh;
179 }
180 if ((id >= MAX_ID_BIT) || (id < 0))
Nadia Derbey944ca052008-07-25 01:47:59 -0700181 return IDR_NOMORE_SPACE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 if (l == 0)
183 break;
184 /*
185 * Create the layer below if it is missing.
186 */
187 if (!p->ary[m]) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700188 new = get_from_free_list(idp);
189 if (!new)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190 return -1;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800191 new->layer = l-1;
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700192 rcu_assign_pointer(p->ary[m], new);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193 p->count++;
194 }
195 pa[l--] = p;
196 p = p->ary[m];
197 }
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900198
199 pa[l] = p;
200 return id;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201}
202
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900203static int idr_get_empty_slot(struct idr *idp, int starting_id,
204 struct idr_layer **pa)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205{
206 struct idr_layer *p, *new;
207 int layers, v, id;
Roland Dreierc259cc22006-07-14 00:24:23 -0700208 unsigned long flags;
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800209
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 id = starting_id;
211build_up:
212 p = idp->top;
213 layers = idp->layers;
214 if (unlikely(!p)) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700215 if (!(p = get_from_free_list(idp)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 return -1;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800217 p->layer = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218 layers = 1;
219 }
220 /*
221 * Add a new layer to the top of the tree if the requested
222 * id is larger than the currently allocated space.
223 */
Zaur Kambarov589777e2005-06-21 17:14:31 -0700224 while ((layers < (MAX_LEVEL - 1)) && (id >= (1 << (layers*IDR_BITS)))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225 layers++;
Manfred Spraul711a49a2008-12-10 18:17:06 +0100226 if (!p->count) {
227 /* special case: if the tree is currently empty,
228 * then we grow the tree by moving the top node
229 * upwards.
230 */
231 p->layer++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232 continue;
Manfred Spraul711a49a2008-12-10 18:17:06 +0100233 }
Nadia Derbey4ae53782008-07-25 01:47:58 -0700234 if (!(new = get_from_free_list(idp))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235 /*
236 * The allocation failed. If we built part of
237 * the structure tear it down.
238 */
Roland Dreierc259cc22006-07-14 00:24:23 -0700239 spin_lock_irqsave(&idp->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240 for (new = p; p && p != idp->top; new = p) {
241 p = p->ary[0];
242 new->ary[0] = NULL;
243 new->bitmap = new->count = 0;
Nadia Derbey4ae53782008-07-25 01:47:58 -0700244 __move_to_free_list(idp, new);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245 }
Roland Dreierc259cc22006-07-14 00:24:23 -0700246 spin_unlock_irqrestore(&idp->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 return -1;
248 }
249 new->ary[0] = p;
250 new->count = 1;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800251 new->layer = layers-1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252 if (p->bitmap == IDR_FULL)
253 __set_bit(0, &new->bitmap);
254 p = new;
255 }
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700256 rcu_assign_pointer(idp->top, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257 idp->layers = layers;
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900258 v = sub_alloc(idp, &id, pa);
Nadia Derbey944ca052008-07-25 01:47:59 -0700259 if (v == IDR_NEED_TO_GROW)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260 goto build_up;
261 return(v);
262}
263
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900264static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id)
265{
266 struct idr_layer *pa[MAX_LEVEL];
267 int id;
268
269 id = idr_get_empty_slot(idp, starting_id, pa);
270 if (id >= 0) {
271 /*
272 * Successfully found an empty slot. Install the user
273 * pointer and mark the slot full.
274 */
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700275 rcu_assign_pointer(pa[0]->ary[id & IDR_MASK],
276 (struct idr_layer *)ptr);
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900277 pa[0]->count++;
278 idr_mark_full(pa, id);
279 }
280
281 return id;
282}
283
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284/**
John McCutchan7c657f22005-08-26 14:02:04 -0400285 * idr_get_new_above - allocate new idr entry above or equal to a start id
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286 * @idp: idr handle
Thadeu Lima de Souza Cascardo94e2bd62009-10-16 15:20:49 +0200287 * @ptr: pointer you want associated with the id
Naohiro Aotaea24ea82010-08-31 00:37:03 +0900288 * @starting_id: id to start search at
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289 * @id: pointer to the allocated handle
290 *
291 * This is the allocate id function. It should be called with any
292 * required locks.
293 *
Naohiro Aota066a9be2010-10-26 14:23:03 -0700294 * If allocation from IDR's private freelist fails, idr_get_new_above() will
Randy Dunlap56083ab2010-10-26 14:19:08 -0700295 * return %-EAGAIN. The caller should retry the idr_pre_get() call to refill
Naohiro Aota066a9be2010-10-26 14:23:03 -0700296 * IDR's preallocation and then retry the idr_get_new_above() call.
297 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700298 * If the idr is full idr_get_new_above() will return %-ENOSPC.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700300 * @id returns a value in the range @starting_id ... %0x7fffffff
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 */
302int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id)
303{
304 int rv;
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800305
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306 rv = idr_get_new_above_int(idp, ptr, starting_id);
307 /*
308 * This is a cheap hack until the IDR code can be fixed to
309 * return proper error values.
310 */
Nadia Derbey944ca052008-07-25 01:47:59 -0700311 if (rv < 0)
312 return _idr_rc_to_errno(rv);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313 *id = rv;
314 return 0;
315}
316EXPORT_SYMBOL(idr_get_new_above);
317
318/**
319 * idr_get_new - allocate new idr entry
320 * @idp: idr handle
Thadeu Lima de Souza Cascardo94e2bd62009-10-16 15:20:49 +0200321 * @ptr: pointer you want associated with the id
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322 * @id: pointer to the allocated handle
323 *
Naohiro Aota066a9be2010-10-26 14:23:03 -0700324 * If allocation from IDR's private freelist fails, idr_get_new_above() will
Randy Dunlap56083ab2010-10-26 14:19:08 -0700325 * return %-EAGAIN. The caller should retry the idr_pre_get() call to refill
Naohiro Aota066a9be2010-10-26 14:23:03 -0700326 * IDR's preallocation and then retry the idr_get_new_above() call.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700328 * If the idr is full idr_get_new_above() will return %-ENOSPC.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700330 * @id returns a value in the range %0 ... %0x7fffffff
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 */
332int idr_get_new(struct idr *idp, void *ptr, int *id)
333{
334 int rv;
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800335
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 rv = idr_get_new_above_int(idp, ptr, 0);
337 /*
338 * This is a cheap hack until the IDR code can be fixed to
339 * return proper error values.
340 */
Nadia Derbey944ca052008-07-25 01:47:59 -0700341 if (rv < 0)
342 return _idr_rc_to_errno(rv);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343 *id = rv;
344 return 0;
345}
346EXPORT_SYMBOL(idr_get_new);
347
348static void idr_remove_warning(int id)
349{
Nadia Derbeyf098ad62008-07-25 01:47:59 -0700350 printk(KERN_WARNING
351 "idr_remove called for id=%d which is not allocated.\n", id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352 dump_stack();
353}
354
355static void sub_remove(struct idr *idp, int shift, int id)
356{
357 struct idr_layer *p = idp->top;
358 struct idr_layer **pa[MAX_LEVEL];
359 struct idr_layer ***paa = &pa[0];
Nadia Derbeycf481c22008-07-25 01:48:02 -0700360 struct idr_layer *to_free;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361 int n;
362
363 *paa = NULL;
364 *++paa = &idp->top;
365
366 while ((shift > 0) && p) {
367 n = (id >> shift) & IDR_MASK;
368 __clear_bit(n, &p->bitmap);
369 *++paa = &p->ary[n];
370 p = p->ary[n];
371 shift -= IDR_BITS;
372 }
373 n = id & IDR_MASK;
374 if (likely(p != NULL && test_bit(n, &p->bitmap))){
375 __clear_bit(n, &p->bitmap);
Nadia Derbeycf481c22008-07-25 01:48:02 -0700376 rcu_assign_pointer(p->ary[n], NULL);
377 to_free = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378 while(*paa && ! --((**paa)->count)){
Nadia Derbeycf481c22008-07-25 01:48:02 -0700379 if (to_free)
380 free_layer(to_free);
381 to_free = **paa;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 **paa-- = NULL;
383 }
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800384 if (!*paa)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385 idp->layers = 0;
Nadia Derbeycf481c22008-07-25 01:48:02 -0700386 if (to_free)
387 free_layer(to_free);
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800388 } else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389 idr_remove_warning(id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390}
391
392/**
Randy Dunlap56083ab2010-10-26 14:19:08 -0700393 * idr_remove - remove the given id and free its slot
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800394 * @idp: idr handle
395 * @id: unique key
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396 */
397void idr_remove(struct idr *idp, int id)
398{
399 struct idr_layer *p;
Nadia Derbeycf481c22008-07-25 01:48:02 -0700400 struct idr_layer *to_free;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401
402 /* Mask off upper bits we don't use for the search. */
403 id &= MAX_ID_MASK;
404
405 sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800406 if (idp->top && idp->top->count == 1 && (idp->layers > 1) &&
Nadia Derbeycf481c22008-07-25 01:48:02 -0700407 idp->top->ary[0]) {
408 /*
409 * Single child at leftmost slot: we can shrink the tree.
410 * This level is not needed anymore since when layers are
411 * inserted, they are inserted at the top of the existing
412 * tree.
413 */
414 to_free = idp->top;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 p = idp->top->ary[0];
Nadia Derbeycf481c22008-07-25 01:48:02 -0700416 rcu_assign_pointer(idp->top, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 --idp->layers;
Nadia Derbeycf481c22008-07-25 01:48:02 -0700418 to_free->bitmap = to_free->count = 0;
419 free_layer(to_free);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420 }
421 while (idp->id_free_cnt >= IDR_FREE_MAX) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700422 p = get_from_free_list(idp);
Nadia Derbeycf481c22008-07-25 01:48:02 -0700423 /*
424 * Note: we don't call the rcu callback here, since the only
425 * layers that fall into the freelist are those that have been
426 * preallocated.
427 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428 kmem_cache_free(idr_layer_cache, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429 }
Nadia Derbeyaf8e2a42008-05-01 04:34:57 -0700430 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431}
432EXPORT_SYMBOL(idr_remove);
433
434/**
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700435 * idr_remove_all - remove all ids from the given idr tree
436 * @idp: idr handle
437 *
438 * idr_destroy() only frees up unused, cached idp_layers, but this
439 * function will remove all id mappings and leave all idp_layers
440 * unused.
441 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700442 * A typical clean-up sequence for objects stored in an idr tree will
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700443 * use idr_for_each() to free all objects, if necessay, then
444 * idr_remove_all() to remove all ids, and idr_destroy() to free
445 * up the cached idr_layers.
446 */
447void idr_remove_all(struct idr *idp)
448{
Oleg Nesterov6ace06dc2007-07-31 00:39:19 -0700449 int n, id, max;
Imre Deak2dcb22b2010-05-26 14:43:38 -0700450 int bt_mask;
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700451 struct idr_layer *p;
452 struct idr_layer *pa[MAX_LEVEL];
453 struct idr_layer **paa = &pa[0];
454
455 n = idp->layers * IDR_BITS;
456 p = idp->top;
Paul E. McKenney1b233362009-03-10 12:55:52 -0700457 rcu_assign_pointer(idp->top, NULL);
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700458 max = 1 << n;
459
460 id = 0;
Oleg Nesterov6ace06dc2007-07-31 00:39:19 -0700461 while (id < max) {
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700462 while (n > IDR_BITS && p) {
463 n -= IDR_BITS;
464 *paa++ = p;
465 p = p->ary[(id >> n) & IDR_MASK];
466 }
467
Imre Deak2dcb22b2010-05-26 14:43:38 -0700468 bt_mask = id;
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700469 id += 1 << n;
Imre Deak2dcb22b2010-05-26 14:43:38 -0700470 /* Get the highest bit that the above add changed from 0->1. */
471 while (n < fls(id ^ bt_mask)) {
Nadia Derbeycf481c22008-07-25 01:48:02 -0700472 if (p)
473 free_layer(p);
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700474 n += IDR_BITS;
475 p = *--paa;
476 }
477 }
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700478 idp->layers = 0;
479}
480EXPORT_SYMBOL(idr_remove_all);
481
482/**
Andrew Morton8d3b3592005-10-23 12:57:18 -0700483 * idr_destroy - release all cached layers within an idr tree
Naohiro Aotaea24ea82010-08-31 00:37:03 +0900484 * @idp: idr handle
Andrew Morton8d3b3592005-10-23 12:57:18 -0700485 */
486void idr_destroy(struct idr *idp)
487{
488 while (idp->id_free_cnt) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700489 struct idr_layer *p = get_from_free_list(idp);
Andrew Morton8d3b3592005-10-23 12:57:18 -0700490 kmem_cache_free(idr_layer_cache, p);
491 }
492}
493EXPORT_SYMBOL(idr_destroy);
494
495/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700496 * idr_find - return pointer for given id
497 * @idp: idr handle
498 * @id: lookup key
499 *
500 * Return the pointer given the id it has been registered with. A %NULL
501 * return indicates that @id is not valid or you passed %NULL in
502 * idr_get_new().
503 *
Nadia Derbeyf9c46d62008-07-25 01:48:01 -0700504 * This function can be called under rcu_read_lock(), given that the leaf
505 * pointers lifetimes are correctly managed.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506 */
507void *idr_find(struct idr *idp, int id)
508{
509 int n;
510 struct idr_layer *p;
511
Paul E. McKenney96be7532010-02-22 17:04:55 -0800512 p = rcu_dereference_raw(idp->top);
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800513 if (!p)
514 return NULL;
515 n = (p->layer+1) * IDR_BITS;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516
517 /* Mask off upper bits we don't use for the search. */
518 id &= MAX_ID_MASK;
519
520 if (id >= (1 << n))
521 return NULL;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800522 BUG_ON(n == 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523
524 while (n > 0 && p) {
525 n -= IDR_BITS;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800526 BUG_ON(n != p->layer*IDR_BITS);
Paul E. McKenney96be7532010-02-22 17:04:55 -0800527 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700528 }
529 return((void *)p);
530}
531EXPORT_SYMBOL(idr_find);
532
Jeff Mahoney5806f072006-06-26 00:27:19 -0700533/**
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700534 * idr_for_each - iterate through all stored pointers
535 * @idp: idr handle
536 * @fn: function to be called for each pointer
537 * @data: data passed back to callback function
538 *
539 * Iterate over the pointers registered with the given idr. The
540 * callback function will be called for each pointer currently
541 * registered, passing the id, the pointer and the data pointer passed
542 * to this function. It is not safe to modify the idr tree while in
543 * the callback, so functions such as idr_get_new and idr_remove are
544 * not allowed.
545 *
546 * We check the return of @fn each time. If it returns anything other
Randy Dunlap56083ab2010-10-26 14:19:08 -0700547 * than %0, we break out and return that value.
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700548 *
549 * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove().
550 */
551int idr_for_each(struct idr *idp,
552 int (*fn)(int id, void *p, void *data), void *data)
553{
554 int n, id, max, error = 0;
555 struct idr_layer *p;
556 struct idr_layer *pa[MAX_LEVEL];
557 struct idr_layer **paa = &pa[0];
558
559 n = idp->layers * IDR_BITS;
Paul E. McKenney96be7532010-02-22 17:04:55 -0800560 p = rcu_dereference_raw(idp->top);
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700561 max = 1 << n;
562
563 id = 0;
564 while (id < max) {
565 while (n > 0 && p) {
566 n -= IDR_BITS;
567 *paa++ = p;
Paul E. McKenney96be7532010-02-22 17:04:55 -0800568 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700569 }
570
571 if (p) {
572 error = fn(id, (void *)p, data);
573 if (error)
574 break;
575 }
576
577 id += 1 << n;
578 while (n < fls(id)) {
579 n += IDR_BITS;
580 p = *--paa;
581 }
582 }
583
584 return error;
585}
586EXPORT_SYMBOL(idr_for_each);
587
588/**
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700589 * idr_get_next - lookup next object of id to given id.
590 * @idp: idr handle
Naohiro Aotaea24ea82010-08-31 00:37:03 +0900591 * @nextidp: pointer to lookup key
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700592 *
593 * Returns pointer to registered object with id, which is next number to
Naohiro Aota1458ce12010-08-27 17:43:46 +0900594 * given id. After being looked up, *@nextidp will be updated for the next
595 * iteration.
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700596 */
597
598void *idr_get_next(struct idr *idp, int *nextidp)
599{
600 struct idr_layer *p, *pa[MAX_LEVEL];
601 struct idr_layer **paa = &pa[0];
602 int id = *nextidp;
603 int n, max;
604
605 /* find first ent */
606 n = idp->layers * IDR_BITS;
607 max = 1 << n;
Paul E. McKenney94bfa3b2010-06-07 17:09:45 -0700608 p = rcu_dereference_raw(idp->top);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700609 if (!p)
610 return NULL;
611
612 while (id < max) {
613 while (n > 0 && p) {
614 n -= IDR_BITS;
615 *paa++ = p;
Paul E. McKenney94bfa3b2010-06-07 17:09:45 -0700616 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700617 }
618
619 if (p) {
620 *nextidp = id;
621 return p;
622 }
623
624 id += 1 << n;
625 while (n < fls(id)) {
626 n += IDR_BITS;
627 p = *--paa;
628 }
629 }
630 return NULL;
631}
Ben Hutchings4d1ee802010-01-29 20:59:17 +0000632EXPORT_SYMBOL(idr_get_next);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700633
634
635/**
Jeff Mahoney5806f072006-06-26 00:27:19 -0700636 * idr_replace - replace pointer for given id
637 * @idp: idr handle
638 * @ptr: pointer you want associated with the id
639 * @id: lookup key
640 *
641 * Replace the pointer registered with an id and return the old value.
Randy Dunlap56083ab2010-10-26 14:19:08 -0700642 * A %-ENOENT return indicates that @id was not found.
643 * A %-EINVAL return indicates that @id was not within valid constraints.
Jeff Mahoney5806f072006-06-26 00:27:19 -0700644 *
Nadia Derbeycf481c22008-07-25 01:48:02 -0700645 * The caller must serialize with writers.
Jeff Mahoney5806f072006-06-26 00:27:19 -0700646 */
647void *idr_replace(struct idr *idp, void *ptr, int id)
648{
649 int n;
650 struct idr_layer *p, *old_p;
651
Jeff Mahoney5806f072006-06-26 00:27:19 -0700652 p = idp->top;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800653 if (!p)
654 return ERR_PTR(-EINVAL);
655
656 n = (p->layer+1) * IDR_BITS;
Jeff Mahoney5806f072006-06-26 00:27:19 -0700657
658 id &= MAX_ID_MASK;
659
660 if (id >= (1 << n))
661 return ERR_PTR(-EINVAL);
662
663 n -= IDR_BITS;
664 while ((n > 0) && p) {
665 p = p->ary[(id >> n) & IDR_MASK];
666 n -= IDR_BITS;
667 }
668
669 n = id & IDR_MASK;
670 if (unlikely(p == NULL || !test_bit(n, &p->bitmap)))
671 return ERR_PTR(-ENOENT);
672
673 old_p = p->ary[n];
Nadia Derbeycf481c22008-07-25 01:48:02 -0700674 rcu_assign_pointer(p->ary[n], ptr);
Jeff Mahoney5806f072006-06-26 00:27:19 -0700675
676 return old_p;
677}
678EXPORT_SYMBOL(idr_replace);
679
Akinobu Mita199f0ca2008-04-29 01:03:13 -0700680void __init idr_init_cache(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681{
Akinobu Mita199f0ca2008-04-29 01:03:13 -0700682 idr_layer_cache = kmem_cache_create("idr_layer_cache",
Andrew Morton5b019e92009-01-15 13:51:21 -0800683 sizeof(struct idr_layer), 0, SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700684}
685
686/**
687 * idr_init - initialize idr handle
688 * @idp: idr handle
689 *
690 * This function is use to set up the handle (@idp) that you will pass
691 * to the rest of the functions.
692 */
693void idr_init(struct idr *idp)
694{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700695 memset(idp, 0, sizeof(struct idr));
696 spin_lock_init(&idp->lock);
697}
698EXPORT_SYMBOL(idr_init);
Tejun Heo72dba582007-06-14 03:45:13 +0900699
700
Randy Dunlap56083ab2010-10-26 14:19:08 -0700701/**
702 * DOC: IDA description
Tejun Heo72dba582007-06-14 03:45:13 +0900703 * IDA - IDR based ID allocator
704 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700705 * This is id allocator without id -> pointer translation. Memory
Tejun Heo72dba582007-06-14 03:45:13 +0900706 * usage is much lower than full blown idr because each id only
707 * occupies a bit. ida uses a custom leaf node which contains
708 * IDA_BITMAP_BITS slots.
709 *
710 * 2007-04-25 written by Tejun Heo <htejun@gmail.com>
711 */
712
713static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap)
714{
715 unsigned long flags;
716
717 if (!ida->free_bitmap) {
718 spin_lock_irqsave(&ida->idr.lock, flags);
719 if (!ida->free_bitmap) {
720 ida->free_bitmap = bitmap;
721 bitmap = NULL;
722 }
723 spin_unlock_irqrestore(&ida->idr.lock, flags);
724 }
725
726 kfree(bitmap);
727}
728
729/**
730 * ida_pre_get - reserve resources for ida allocation
731 * @ida: ida handle
732 * @gfp_mask: memory allocation flag
733 *
734 * This function should be called prior to locking and calling the
735 * following function. It preallocates enough memory to satisfy the
736 * worst possible allocation.
737 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700738 * If the system is REALLY out of memory this function returns %0,
739 * otherwise %1.
Tejun Heo72dba582007-06-14 03:45:13 +0900740 */
741int ida_pre_get(struct ida *ida, gfp_t gfp_mask)
742{
743 /* allocate idr_layers */
744 if (!idr_pre_get(&ida->idr, gfp_mask))
745 return 0;
746
747 /* allocate free_bitmap */
748 if (!ida->free_bitmap) {
749 struct ida_bitmap *bitmap;
750
751 bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask);
752 if (!bitmap)
753 return 0;
754
755 free_bitmap(ida, bitmap);
756 }
757
758 return 1;
759}
760EXPORT_SYMBOL(ida_pre_get);
761
762/**
763 * ida_get_new_above - allocate new ID above or equal to a start id
764 * @ida: ida handle
Naohiro Aotaea24ea82010-08-31 00:37:03 +0900765 * @starting_id: id to start search at
Tejun Heo72dba582007-06-14 03:45:13 +0900766 * @p_id: pointer to the allocated handle
767 *
768 * Allocate new ID above or equal to @ida. It should be called with
769 * any required locks.
770 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700771 * If memory is required, it will return %-EAGAIN, you should unlock
Tejun Heo72dba582007-06-14 03:45:13 +0900772 * and go back to the ida_pre_get() call. If the ida is full, it will
Randy Dunlap56083ab2010-10-26 14:19:08 -0700773 * return %-ENOSPC.
Tejun Heo72dba582007-06-14 03:45:13 +0900774 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700775 * @p_id returns a value in the range @starting_id ... %0x7fffffff.
Tejun Heo72dba582007-06-14 03:45:13 +0900776 */
777int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
778{
779 struct idr_layer *pa[MAX_LEVEL];
780 struct ida_bitmap *bitmap;
781 unsigned long flags;
782 int idr_id = starting_id / IDA_BITMAP_BITS;
783 int offset = starting_id % IDA_BITMAP_BITS;
784 int t, id;
785
786 restart:
787 /* get vacant slot */
788 t = idr_get_empty_slot(&ida->idr, idr_id, pa);
Nadia Derbey944ca052008-07-25 01:47:59 -0700789 if (t < 0)
790 return _idr_rc_to_errno(t);
Tejun Heo72dba582007-06-14 03:45:13 +0900791
792 if (t * IDA_BITMAP_BITS >= MAX_ID_BIT)
793 return -ENOSPC;
794
795 if (t != idr_id)
796 offset = 0;
797 idr_id = t;
798
799 /* if bitmap isn't there, create a new one */
800 bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK];
801 if (!bitmap) {
802 spin_lock_irqsave(&ida->idr.lock, flags);
803 bitmap = ida->free_bitmap;
804 ida->free_bitmap = NULL;
805 spin_unlock_irqrestore(&ida->idr.lock, flags);
806
807 if (!bitmap)
808 return -EAGAIN;
809
810 memset(bitmap, 0, sizeof(struct ida_bitmap));
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700811 rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK],
812 (void *)bitmap);
Tejun Heo72dba582007-06-14 03:45:13 +0900813 pa[0]->count++;
814 }
815
816 /* lookup for empty slot */
817 t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset);
818 if (t == IDA_BITMAP_BITS) {
819 /* no empty slot after offset, continue to the next chunk */
820 idr_id++;
821 offset = 0;
822 goto restart;
823 }
824
825 id = idr_id * IDA_BITMAP_BITS + t;
826 if (id >= MAX_ID_BIT)
827 return -ENOSPC;
828
829 __set_bit(t, bitmap->bitmap);
830 if (++bitmap->nr_busy == IDA_BITMAP_BITS)
831 idr_mark_full(pa, idr_id);
832
833 *p_id = id;
834
835 /* Each leaf node can handle nearly a thousand slots and the
836 * whole idea of ida is to have small memory foot print.
837 * Throw away extra resources one by one after each successful
838 * allocation.
839 */
840 if (ida->idr.id_free_cnt || ida->free_bitmap) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700841 struct idr_layer *p = get_from_free_list(&ida->idr);
Tejun Heo72dba582007-06-14 03:45:13 +0900842 if (p)
843 kmem_cache_free(idr_layer_cache, p);
844 }
845
846 return 0;
847}
848EXPORT_SYMBOL(ida_get_new_above);
849
850/**
851 * ida_get_new - allocate new ID
852 * @ida: idr handle
853 * @p_id: pointer to the allocated handle
854 *
855 * Allocate new ID. It should be called with any required locks.
856 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700857 * If memory is required, it will return %-EAGAIN, you should unlock
Tejun Heo72dba582007-06-14 03:45:13 +0900858 * and go back to the idr_pre_get() call. If the idr is full, it will
Randy Dunlap56083ab2010-10-26 14:19:08 -0700859 * return %-ENOSPC.
Tejun Heo72dba582007-06-14 03:45:13 +0900860 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700861 * @id returns a value in the range %0 ... %0x7fffffff.
Tejun Heo72dba582007-06-14 03:45:13 +0900862 */
863int ida_get_new(struct ida *ida, int *p_id)
864{
865 return ida_get_new_above(ida, 0, p_id);
866}
867EXPORT_SYMBOL(ida_get_new);
868
869/**
870 * ida_remove - remove the given ID
871 * @ida: ida handle
872 * @id: ID to free
873 */
874void ida_remove(struct ida *ida, int id)
875{
876 struct idr_layer *p = ida->idr.top;
877 int shift = (ida->idr.layers - 1) * IDR_BITS;
878 int idr_id = id / IDA_BITMAP_BITS;
879 int offset = id % IDA_BITMAP_BITS;
880 int n;
881 struct ida_bitmap *bitmap;
882
883 /* clear full bits while looking up the leaf idr_layer */
884 while ((shift > 0) && p) {
885 n = (idr_id >> shift) & IDR_MASK;
886 __clear_bit(n, &p->bitmap);
887 p = p->ary[n];
888 shift -= IDR_BITS;
889 }
890
891 if (p == NULL)
892 goto err;
893
894 n = idr_id & IDR_MASK;
895 __clear_bit(n, &p->bitmap);
896
897 bitmap = (void *)p->ary[n];
898 if (!test_bit(offset, bitmap->bitmap))
899 goto err;
900
901 /* update bitmap and remove it if empty */
902 __clear_bit(offset, bitmap->bitmap);
903 if (--bitmap->nr_busy == 0) {
904 __set_bit(n, &p->bitmap); /* to please idr_remove() */
905 idr_remove(&ida->idr, idr_id);
906 free_bitmap(ida, bitmap);
907 }
908
909 return;
910
911 err:
912 printk(KERN_WARNING
913 "ida_remove called for id=%d which is not allocated.\n", id);
914}
915EXPORT_SYMBOL(ida_remove);
916
917/**
918 * ida_destroy - release all cached layers within an ida tree
Naohiro Aotaea24ea82010-08-31 00:37:03 +0900919 * @ida: ida handle
Tejun Heo72dba582007-06-14 03:45:13 +0900920 */
921void ida_destroy(struct ida *ida)
922{
923 idr_destroy(&ida->idr);
924 kfree(ida->free_bitmap);
925}
926EXPORT_SYMBOL(ida_destroy);
927
928/**
929 * ida_init - initialize ida handle
930 * @ida: ida handle
931 *
932 * This function is use to set up the handle (@ida) that you will pass
933 * to the rest of the functions.
934 */
935void ida_init(struct ida *ida)
936{
937 memset(ida, 0, sizeof(struct ida));
938 idr_init(&ida->idr);
939
940}
941EXPORT_SYMBOL(ida_init);