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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/**
109 * idr_pre_get - reserver resources for idr allocation
110 * @idp: idr handle
111 * @gfp_mask: memory allocation flags
112 *
113 * This function should be called prior to locking and calling the
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700114 * idr_get_new* functions. It preallocates enough memory to satisfy
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115 * the worst possible allocation.
116 *
117 * If the system is REALLY out of memory this function returns 0,
118 * otherwise 1.
119 */
Al Virofd4f2df2005-10-21 03:18:50 -0400120int idr_pre_get(struct idr *idp, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121{
122 while (idp->id_free_cnt < IDR_FREE_MAX) {
123 struct idr_layer *new;
124 new = kmem_cache_alloc(idr_layer_cache, gfp_mask);
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800125 if (new == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126 return (0);
Nadia Derbey4ae53782008-07-25 01:47:58 -0700127 move_to_free_list(idp, new);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 }
129 return 1;
130}
131EXPORT_SYMBOL(idr_pre_get);
132
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900133static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134{
135 int n, m, sh;
136 struct idr_layer *p, *new;
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900137 int l, id, oid;
Al Viro5ba25332007-10-14 19:35:50 +0100138 unsigned long bm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139
140 id = *starting_id;
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900141 restart:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 p = idp->top;
143 l = idp->layers;
144 pa[l--] = NULL;
145 while (1) {
146 /*
147 * We run around this while until we reach the leaf node...
148 */
149 n = (id >> (IDR_BITS*l)) & IDR_MASK;
150 bm = ~p->bitmap;
151 m = find_next_bit(&bm, IDR_SIZE, n);
152 if (m == IDR_SIZE) {
153 /* no space available go back to previous layer. */
154 l++;
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900155 oid = id;
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800156 id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1;
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900157
158 /* if already at the top layer, we need to grow */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 if (!(p = pa[l])) {
160 *starting_id = id;
Nadia Derbey944ca052008-07-25 01:47:59 -0700161 return IDR_NEED_TO_GROW;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 }
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900163
164 /* If we need to go up one layer, continue the
165 * loop; otherwise, restart from the top.
166 */
167 sh = IDR_BITS * (l + 1);
168 if (oid >> sh == id >> sh)
169 continue;
170 else
171 goto restart;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 }
173 if (m != n) {
174 sh = IDR_BITS*l;
175 id = ((id >> sh) ^ n ^ m) << sh;
176 }
177 if ((id >= MAX_ID_BIT) || (id < 0))
Nadia Derbey944ca052008-07-25 01:47:59 -0700178 return IDR_NOMORE_SPACE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179 if (l == 0)
180 break;
181 /*
182 * Create the layer below if it is missing.
183 */
184 if (!p->ary[m]) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700185 new = get_from_free_list(idp);
186 if (!new)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187 return -1;
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700188 rcu_assign_pointer(p->ary[m], new);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 p->count++;
190 }
191 pa[l--] = p;
192 p = p->ary[m];
193 }
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900194
195 pa[l] = p;
196 return id;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197}
198
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900199static int idr_get_empty_slot(struct idr *idp, int starting_id,
200 struct idr_layer **pa)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201{
202 struct idr_layer *p, *new;
203 int layers, v, id;
Roland Dreierc259cc22006-07-14 00:24:23 -0700204 unsigned long flags;
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800205
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206 id = starting_id;
207build_up:
208 p = idp->top;
209 layers = idp->layers;
210 if (unlikely(!p)) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700211 if (!(p = get_from_free_list(idp)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212 return -1;
213 layers = 1;
214 }
215 /*
216 * Add a new layer to the top of the tree if the requested
217 * id is larger than the currently allocated space.
218 */
Zaur Kambarov589777e2005-06-21 17:14:31 -0700219 while ((layers < (MAX_LEVEL - 1)) && (id >= (1 << (layers*IDR_BITS)))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220 layers++;
221 if (!p->count)
222 continue;
Nadia Derbey4ae53782008-07-25 01:47:58 -0700223 if (!(new = get_from_free_list(idp))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224 /*
225 * The allocation failed. If we built part of
226 * the structure tear it down.
227 */
Roland Dreierc259cc22006-07-14 00:24:23 -0700228 spin_lock_irqsave(&idp->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229 for (new = p; p && p != idp->top; new = p) {
230 p = p->ary[0];
231 new->ary[0] = NULL;
232 new->bitmap = new->count = 0;
Nadia Derbey4ae53782008-07-25 01:47:58 -0700233 __move_to_free_list(idp, new);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234 }
Roland Dreierc259cc22006-07-14 00:24:23 -0700235 spin_unlock_irqrestore(&idp->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236 return -1;
237 }
238 new->ary[0] = p;
239 new->count = 1;
240 if (p->bitmap == IDR_FULL)
241 __set_bit(0, &new->bitmap);
242 p = new;
243 }
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700244 rcu_assign_pointer(idp->top, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245 idp->layers = layers;
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900246 v = sub_alloc(idp, &id, pa);
Nadia Derbey944ca052008-07-25 01:47:59 -0700247 if (v == IDR_NEED_TO_GROW)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248 goto build_up;
249 return(v);
250}
251
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900252static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id)
253{
254 struct idr_layer *pa[MAX_LEVEL];
255 int id;
256
257 id = idr_get_empty_slot(idp, starting_id, pa);
258 if (id >= 0) {
259 /*
260 * Successfully found an empty slot. Install the user
261 * pointer and mark the slot full.
262 */
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700263 rcu_assign_pointer(pa[0]->ary[id & IDR_MASK],
264 (struct idr_layer *)ptr);
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900265 pa[0]->count++;
266 idr_mark_full(pa, id);
267 }
268
269 return id;
270}
271
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272/**
John McCutchan7c657f22005-08-26 14:02:04 -0400273 * idr_get_new_above - allocate new idr entry above or equal to a start id
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 * @idp: idr handle
275 * @ptr: pointer you want associated with the ide
276 * @start_id: id to start search at
277 * @id: pointer to the allocated handle
278 *
279 * This is the allocate id function. It should be called with any
280 * required locks.
281 *
282 * If memory is required, it will return -EAGAIN, you should unlock
283 * and go back to the idr_pre_get() call. If the idr is full, it will
284 * return -ENOSPC.
285 *
286 * @id returns a value in the range 0 ... 0x7fffffff
287 */
288int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id)
289{
290 int rv;
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800291
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292 rv = idr_get_new_above_int(idp, ptr, starting_id);
293 /*
294 * This is a cheap hack until the IDR code can be fixed to
295 * return proper error values.
296 */
Nadia Derbey944ca052008-07-25 01:47:59 -0700297 if (rv < 0)
298 return _idr_rc_to_errno(rv);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 *id = rv;
300 return 0;
301}
302EXPORT_SYMBOL(idr_get_new_above);
303
304/**
305 * idr_get_new - allocate new idr entry
306 * @idp: idr handle
307 * @ptr: pointer you want associated with the ide
308 * @id: pointer to the allocated handle
309 *
310 * This is the allocate id function. It should be called with any
311 * required locks.
312 *
313 * If memory is required, it will return -EAGAIN, you should unlock
314 * and go back to the idr_pre_get() call. If the idr is full, it will
315 * return -ENOSPC.
316 *
317 * @id returns a value in the range 0 ... 0x7fffffff
318 */
319int idr_get_new(struct idr *idp, void *ptr, int *id)
320{
321 int rv;
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800322
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 rv = idr_get_new_above_int(idp, ptr, 0);
324 /*
325 * This is a cheap hack until the IDR code can be fixed to
326 * return proper error values.
327 */
Nadia Derbey944ca052008-07-25 01:47:59 -0700328 if (rv < 0)
329 return _idr_rc_to_errno(rv);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330 *id = rv;
331 return 0;
332}
333EXPORT_SYMBOL(idr_get_new);
334
335static void idr_remove_warning(int id)
336{
Nadia Derbeyf098ad62008-07-25 01:47:59 -0700337 printk(KERN_WARNING
338 "idr_remove called for id=%d which is not allocated.\n", id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339 dump_stack();
340}
341
342static void sub_remove(struct idr *idp, int shift, int id)
343{
344 struct idr_layer *p = idp->top;
345 struct idr_layer **pa[MAX_LEVEL];
346 struct idr_layer ***paa = &pa[0];
Nadia Derbeycf481c22008-07-25 01:48:02 -0700347 struct idr_layer *to_free;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348 int n;
349
350 *paa = NULL;
351 *++paa = &idp->top;
352
353 while ((shift > 0) && p) {
354 n = (id >> shift) & IDR_MASK;
355 __clear_bit(n, &p->bitmap);
356 *++paa = &p->ary[n];
357 p = p->ary[n];
358 shift -= IDR_BITS;
359 }
360 n = id & IDR_MASK;
361 if (likely(p != NULL && test_bit(n, &p->bitmap))){
362 __clear_bit(n, &p->bitmap);
Nadia Derbeycf481c22008-07-25 01:48:02 -0700363 rcu_assign_pointer(p->ary[n], NULL);
364 to_free = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365 while(*paa && ! --((**paa)->count)){
Nadia Derbeycf481c22008-07-25 01:48:02 -0700366 if (to_free)
367 free_layer(to_free);
368 to_free = **paa;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369 **paa-- = NULL;
370 }
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800371 if (!*paa)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372 idp->layers = 0;
Nadia Derbeycf481c22008-07-25 01:48:02 -0700373 if (to_free)
374 free_layer(to_free);
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800375 } else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376 idr_remove_warning(id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377}
378
379/**
380 * idr_remove - remove the given id and free it's slot
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800381 * @idp: idr handle
382 * @id: unique key
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383 */
384void idr_remove(struct idr *idp, int id)
385{
386 struct idr_layer *p;
Nadia Derbeycf481c22008-07-25 01:48:02 -0700387 struct idr_layer *to_free;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388
389 /* Mask off upper bits we don't use for the search. */
390 id &= MAX_ID_MASK;
391
392 sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800393 if (idp->top && idp->top->count == 1 && (idp->layers > 1) &&
Nadia Derbeycf481c22008-07-25 01:48:02 -0700394 idp->top->ary[0]) {
395 /*
396 * Single child at leftmost slot: we can shrink the tree.
397 * This level is not needed anymore since when layers are
398 * inserted, they are inserted at the top of the existing
399 * tree.
400 */
401 to_free = idp->top;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402 p = idp->top->ary[0];
Nadia Derbeycf481c22008-07-25 01:48:02 -0700403 rcu_assign_pointer(idp->top, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404 --idp->layers;
Nadia Derbeycf481c22008-07-25 01:48:02 -0700405 to_free->bitmap = to_free->count = 0;
406 free_layer(to_free);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700407 }
408 while (idp->id_free_cnt >= IDR_FREE_MAX) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700409 p = get_from_free_list(idp);
Nadia Derbeycf481c22008-07-25 01:48:02 -0700410 /*
411 * Note: we don't call the rcu callback here, since the only
412 * layers that fall into the freelist are those that have been
413 * preallocated.
414 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 kmem_cache_free(idr_layer_cache, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 }
Nadia Derbeyaf8e2a42008-05-01 04:34:57 -0700417 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418}
419EXPORT_SYMBOL(idr_remove);
420
421/**
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700422 * idr_remove_all - remove all ids from the given idr tree
423 * @idp: idr handle
424 *
425 * idr_destroy() only frees up unused, cached idp_layers, but this
426 * function will remove all id mappings and leave all idp_layers
427 * unused.
428 *
429 * A typical clean-up sequence for objects stored in an idr tree, will
430 * use idr_for_each() to free all objects, if necessay, then
431 * idr_remove_all() to remove all ids, and idr_destroy() to free
432 * up the cached idr_layers.
433 */
434void idr_remove_all(struct idr *idp)
435{
Oleg Nesterov6ace06d2007-07-31 00:39:19 -0700436 int n, id, max;
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700437 struct idr_layer *p;
438 struct idr_layer *pa[MAX_LEVEL];
439 struct idr_layer **paa = &pa[0];
440
441 n = idp->layers * IDR_BITS;
442 p = idp->top;
443 max = 1 << n;
444
445 id = 0;
Oleg Nesterov6ace06d2007-07-31 00:39:19 -0700446 while (id < max) {
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700447 while (n > IDR_BITS && p) {
448 n -= IDR_BITS;
449 *paa++ = p;
450 p = p->ary[(id >> n) & IDR_MASK];
451 }
452
453 id += 1 << n;
454 while (n < fls(id)) {
Nadia Derbeycf481c22008-07-25 01:48:02 -0700455 if (p)
456 free_layer(p);
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700457 n += IDR_BITS;
458 p = *--paa;
459 }
460 }
Nadia Derbeycf481c22008-07-25 01:48:02 -0700461 rcu_assign_pointer(idp->top, NULL);
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700462 idp->layers = 0;
463}
464EXPORT_SYMBOL(idr_remove_all);
465
466/**
Andrew Morton8d3b3592005-10-23 12:57:18 -0700467 * idr_destroy - release all cached layers within an idr tree
468 * idp: idr handle
469 */
470void idr_destroy(struct idr *idp)
471{
472 while (idp->id_free_cnt) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700473 struct idr_layer *p = get_from_free_list(idp);
Andrew Morton8d3b3592005-10-23 12:57:18 -0700474 kmem_cache_free(idr_layer_cache, p);
475 }
476}
477EXPORT_SYMBOL(idr_destroy);
478
479/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480 * idr_find - return pointer for given id
481 * @idp: idr handle
482 * @id: lookup key
483 *
484 * Return the pointer given the id it has been registered with. A %NULL
485 * return indicates that @id is not valid or you passed %NULL in
486 * idr_get_new().
487 *
Nadia Derbeyf9c46d62008-07-25 01:48:01 -0700488 * This function can be called under rcu_read_lock(), given that the leaf
489 * pointers lifetimes are correctly managed.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490 */
491void *idr_find(struct idr *idp, int id)
492{
493 int n;
494 struct idr_layer *p;
495
496 n = idp->layers * IDR_BITS;
Nadia Derbeyf9c46d62008-07-25 01:48:01 -0700497 p = rcu_dereference(idp->top);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498
499 /* Mask off upper bits we don't use for the search. */
500 id &= MAX_ID_MASK;
501
502 if (id >= (1 << n))
503 return NULL;
504
505 while (n > 0 && p) {
506 n -= IDR_BITS;
Nadia Derbeyf9c46d62008-07-25 01:48:01 -0700507 p = rcu_dereference(p->ary[(id >> n) & IDR_MASK]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508 }
509 return((void *)p);
510}
511EXPORT_SYMBOL(idr_find);
512
Jeff Mahoney5806f072006-06-26 00:27:19 -0700513/**
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700514 * idr_for_each - iterate through all stored pointers
515 * @idp: idr handle
516 * @fn: function to be called for each pointer
517 * @data: data passed back to callback function
518 *
519 * Iterate over the pointers registered with the given idr. The
520 * callback function will be called for each pointer currently
521 * registered, passing the id, the pointer and the data pointer passed
522 * to this function. It is not safe to modify the idr tree while in
523 * the callback, so functions such as idr_get_new and idr_remove are
524 * not allowed.
525 *
526 * We check the return of @fn each time. If it returns anything other
527 * than 0, we break out and return that value.
528 *
529 * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove().
530 */
531int idr_for_each(struct idr *idp,
532 int (*fn)(int id, void *p, void *data), void *data)
533{
534 int n, id, max, error = 0;
535 struct idr_layer *p;
536 struct idr_layer *pa[MAX_LEVEL];
537 struct idr_layer **paa = &pa[0];
538
539 n = idp->layers * IDR_BITS;
Nadia Derbeyf9c46d62008-07-25 01:48:01 -0700540 p = rcu_dereference(idp->top);
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700541 max = 1 << n;
542
543 id = 0;
544 while (id < max) {
545 while (n > 0 && p) {
546 n -= IDR_BITS;
547 *paa++ = p;
Nadia Derbeyf9c46d62008-07-25 01:48:01 -0700548 p = rcu_dereference(p->ary[(id >> n) & IDR_MASK]);
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700549 }
550
551 if (p) {
552 error = fn(id, (void *)p, data);
553 if (error)
554 break;
555 }
556
557 id += 1 << n;
558 while (n < fls(id)) {
559 n += IDR_BITS;
560 p = *--paa;
561 }
562 }
563
564 return error;
565}
566EXPORT_SYMBOL(idr_for_each);
567
568/**
Jeff Mahoney5806f072006-06-26 00:27:19 -0700569 * idr_replace - replace pointer for given id
570 * @idp: idr handle
571 * @ptr: pointer you want associated with the id
572 * @id: lookup key
573 *
574 * Replace the pointer registered with an id and return the old value.
575 * A -ENOENT return indicates that @id was not found.
576 * A -EINVAL return indicates that @id was not within valid constraints.
577 *
Nadia Derbeycf481c22008-07-25 01:48:02 -0700578 * The caller must serialize with writers.
Jeff Mahoney5806f072006-06-26 00:27:19 -0700579 */
580void *idr_replace(struct idr *idp, void *ptr, int id)
581{
582 int n;
583 struct idr_layer *p, *old_p;
584
585 n = idp->layers * IDR_BITS;
586 p = idp->top;
587
588 id &= MAX_ID_MASK;
589
590 if (id >= (1 << n))
591 return ERR_PTR(-EINVAL);
592
593 n -= IDR_BITS;
594 while ((n > 0) && p) {
595 p = p->ary[(id >> n) & IDR_MASK];
596 n -= IDR_BITS;
597 }
598
599 n = id & IDR_MASK;
600 if (unlikely(p == NULL || !test_bit(n, &p->bitmap)))
601 return ERR_PTR(-ENOENT);
602
603 old_p = p->ary[n];
Nadia Derbeycf481c22008-07-25 01:48:02 -0700604 rcu_assign_pointer(p->ary[n], ptr);
Jeff Mahoney5806f072006-06-26 00:27:19 -0700605
606 return old_p;
607}
608EXPORT_SYMBOL(idr_replace);
609
Christoph Lameter4ba9b9d2007-10-16 23:25:51 -0700610static void idr_cache_ctor(struct kmem_cache *idr_layer_cache, void *idr_layer)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700611{
612 memset(idr_layer, 0, sizeof(struct idr_layer));
613}
614
Akinobu Mita199f0ca2008-04-29 01:03:13 -0700615void __init idr_init_cache(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700616{
Akinobu Mita199f0ca2008-04-29 01:03:13 -0700617 idr_layer_cache = kmem_cache_create("idr_layer_cache",
618 sizeof(struct idr_layer), 0, SLAB_PANIC,
619 idr_cache_ctor);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620}
621
622/**
623 * idr_init - initialize idr handle
624 * @idp: idr handle
625 *
626 * This function is use to set up the handle (@idp) that you will pass
627 * to the rest of the functions.
628 */
629void idr_init(struct idr *idp)
630{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700631 memset(idp, 0, sizeof(struct idr));
632 spin_lock_init(&idp->lock);
633}
634EXPORT_SYMBOL(idr_init);
Tejun Heo72dba582007-06-14 03:45:13 +0900635
636
637/*
638 * IDA - IDR based ID allocator
639 *
640 * this is id allocator without id -> pointer translation. Memory
641 * usage is much lower than full blown idr because each id only
642 * occupies a bit. ida uses a custom leaf node which contains
643 * IDA_BITMAP_BITS slots.
644 *
645 * 2007-04-25 written by Tejun Heo <htejun@gmail.com>
646 */
647
648static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap)
649{
650 unsigned long flags;
651
652 if (!ida->free_bitmap) {
653 spin_lock_irqsave(&ida->idr.lock, flags);
654 if (!ida->free_bitmap) {
655 ida->free_bitmap = bitmap;
656 bitmap = NULL;
657 }
658 spin_unlock_irqrestore(&ida->idr.lock, flags);
659 }
660
661 kfree(bitmap);
662}
663
664/**
665 * ida_pre_get - reserve resources for ida allocation
666 * @ida: ida handle
667 * @gfp_mask: memory allocation flag
668 *
669 * This function should be called prior to locking and calling the
670 * following function. It preallocates enough memory to satisfy the
671 * worst possible allocation.
672 *
673 * If the system is REALLY out of memory this function returns 0,
674 * otherwise 1.
675 */
676int ida_pre_get(struct ida *ida, gfp_t gfp_mask)
677{
678 /* allocate idr_layers */
679 if (!idr_pre_get(&ida->idr, gfp_mask))
680 return 0;
681
682 /* allocate free_bitmap */
683 if (!ida->free_bitmap) {
684 struct ida_bitmap *bitmap;
685
686 bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask);
687 if (!bitmap)
688 return 0;
689
690 free_bitmap(ida, bitmap);
691 }
692
693 return 1;
694}
695EXPORT_SYMBOL(ida_pre_get);
696
697/**
698 * ida_get_new_above - allocate new ID above or equal to a start id
699 * @ida: ida handle
700 * @staring_id: id to start search at
701 * @p_id: pointer to the allocated handle
702 *
703 * Allocate new ID above or equal to @ida. It should be called with
704 * any required locks.
705 *
706 * If memory is required, it will return -EAGAIN, you should unlock
707 * and go back to the ida_pre_get() call. If the ida is full, it will
708 * return -ENOSPC.
709 *
710 * @p_id returns a value in the range 0 ... 0x7fffffff.
711 */
712int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
713{
714 struct idr_layer *pa[MAX_LEVEL];
715 struct ida_bitmap *bitmap;
716 unsigned long flags;
717 int idr_id = starting_id / IDA_BITMAP_BITS;
718 int offset = starting_id % IDA_BITMAP_BITS;
719 int t, id;
720
721 restart:
722 /* get vacant slot */
723 t = idr_get_empty_slot(&ida->idr, idr_id, pa);
Nadia Derbey944ca052008-07-25 01:47:59 -0700724 if (t < 0)
725 return _idr_rc_to_errno(t);
Tejun Heo72dba582007-06-14 03:45:13 +0900726
727 if (t * IDA_BITMAP_BITS >= MAX_ID_BIT)
728 return -ENOSPC;
729
730 if (t != idr_id)
731 offset = 0;
732 idr_id = t;
733
734 /* if bitmap isn't there, create a new one */
735 bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK];
736 if (!bitmap) {
737 spin_lock_irqsave(&ida->idr.lock, flags);
738 bitmap = ida->free_bitmap;
739 ida->free_bitmap = NULL;
740 spin_unlock_irqrestore(&ida->idr.lock, flags);
741
742 if (!bitmap)
743 return -EAGAIN;
744
745 memset(bitmap, 0, sizeof(struct ida_bitmap));
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700746 rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK],
747 (void *)bitmap);
Tejun Heo72dba582007-06-14 03:45:13 +0900748 pa[0]->count++;
749 }
750
751 /* lookup for empty slot */
752 t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset);
753 if (t == IDA_BITMAP_BITS) {
754 /* no empty slot after offset, continue to the next chunk */
755 idr_id++;
756 offset = 0;
757 goto restart;
758 }
759
760 id = idr_id * IDA_BITMAP_BITS + t;
761 if (id >= MAX_ID_BIT)
762 return -ENOSPC;
763
764 __set_bit(t, bitmap->bitmap);
765 if (++bitmap->nr_busy == IDA_BITMAP_BITS)
766 idr_mark_full(pa, idr_id);
767
768 *p_id = id;
769
770 /* Each leaf node can handle nearly a thousand slots and the
771 * whole idea of ida is to have small memory foot print.
772 * Throw away extra resources one by one after each successful
773 * allocation.
774 */
775 if (ida->idr.id_free_cnt || ida->free_bitmap) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700776 struct idr_layer *p = get_from_free_list(&ida->idr);
Tejun Heo72dba582007-06-14 03:45:13 +0900777 if (p)
778 kmem_cache_free(idr_layer_cache, p);
779 }
780
781 return 0;
782}
783EXPORT_SYMBOL(ida_get_new_above);
784
785/**
786 * ida_get_new - allocate new ID
787 * @ida: idr handle
788 * @p_id: pointer to the allocated handle
789 *
790 * Allocate new ID. It should be called with any required locks.
791 *
792 * If memory is required, it will return -EAGAIN, you should unlock
793 * and go back to the idr_pre_get() call. If the idr is full, it will
794 * return -ENOSPC.
795 *
796 * @id returns a value in the range 0 ... 0x7fffffff.
797 */
798int ida_get_new(struct ida *ida, int *p_id)
799{
800 return ida_get_new_above(ida, 0, p_id);
801}
802EXPORT_SYMBOL(ida_get_new);
803
804/**
805 * ida_remove - remove the given ID
806 * @ida: ida handle
807 * @id: ID to free
808 */
809void ida_remove(struct ida *ida, int id)
810{
811 struct idr_layer *p = ida->idr.top;
812 int shift = (ida->idr.layers - 1) * IDR_BITS;
813 int idr_id = id / IDA_BITMAP_BITS;
814 int offset = id % IDA_BITMAP_BITS;
815 int n;
816 struct ida_bitmap *bitmap;
817
818 /* clear full bits while looking up the leaf idr_layer */
819 while ((shift > 0) && p) {
820 n = (idr_id >> shift) & IDR_MASK;
821 __clear_bit(n, &p->bitmap);
822 p = p->ary[n];
823 shift -= IDR_BITS;
824 }
825
826 if (p == NULL)
827 goto err;
828
829 n = idr_id & IDR_MASK;
830 __clear_bit(n, &p->bitmap);
831
832 bitmap = (void *)p->ary[n];
833 if (!test_bit(offset, bitmap->bitmap))
834 goto err;
835
836 /* update bitmap and remove it if empty */
837 __clear_bit(offset, bitmap->bitmap);
838 if (--bitmap->nr_busy == 0) {
839 __set_bit(n, &p->bitmap); /* to please idr_remove() */
840 idr_remove(&ida->idr, idr_id);
841 free_bitmap(ida, bitmap);
842 }
843
844 return;
845
846 err:
847 printk(KERN_WARNING
848 "ida_remove called for id=%d which is not allocated.\n", id);
849}
850EXPORT_SYMBOL(ida_remove);
851
852/**
853 * ida_destroy - release all cached layers within an ida tree
854 * ida: ida handle
855 */
856void ida_destroy(struct ida *ida)
857{
858 idr_destroy(&ida->idr);
859 kfree(ida->free_bitmap);
860}
861EXPORT_SYMBOL(ida_destroy);
862
863/**
864 * ida_init - initialize ida handle
865 * @ida: ida handle
866 *
867 * This function is use to set up the handle (@ida) that you will pass
868 * to the rest of the functions.
869 */
870void ida_init(struct ida *ida)
871{
872 memset(ida, 0, sizeof(struct ida));
873 idr_init(&ida->idr);
874
875}
876EXPORT_SYMBOL(ida_init);