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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;
Andrew Morton5b019e92009-01-15 13:51:21 -0800124 new = kmem_cache_zalloc(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;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800188 new->layer = l-1;
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700189 rcu_assign_pointer(p->ary[m], new);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190 p->count++;
191 }
192 pa[l--] = p;
193 p = p->ary[m];
194 }
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900195
196 pa[l] = p;
197 return id;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198}
199
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900200static int idr_get_empty_slot(struct idr *idp, int starting_id,
201 struct idr_layer **pa)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202{
203 struct idr_layer *p, *new;
204 int layers, v, id;
Roland Dreierc259cc22006-07-14 00:24:23 -0700205 unsigned long flags;
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800206
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207 id = starting_id;
208build_up:
209 p = idp->top;
210 layers = idp->layers;
211 if (unlikely(!p)) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700212 if (!(p = get_from_free_list(idp)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213 return -1;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800214 p->layer = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215 layers = 1;
216 }
217 /*
218 * Add a new layer to the top of the tree if the requested
219 * id is larger than the currently allocated space.
220 */
Zaur Kambarov589777e2005-06-21 17:14:31 -0700221 while ((layers < (MAX_LEVEL - 1)) && (id >= (1 << (layers*IDR_BITS)))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222 layers++;
Manfred Spraul711a49a2008-12-10 18:17:06 +0100223 if (!p->count) {
224 /* special case: if the tree is currently empty,
225 * then we grow the tree by moving the top node
226 * upwards.
227 */
228 p->layer++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229 continue;
Manfred Spraul711a49a2008-12-10 18:17:06 +0100230 }
Nadia Derbey4ae53782008-07-25 01:47:58 -0700231 if (!(new = get_from_free_list(idp))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232 /*
233 * The allocation failed. If we built part of
234 * the structure tear it down.
235 */
Roland Dreierc259cc22006-07-14 00:24:23 -0700236 spin_lock_irqsave(&idp->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237 for (new = p; p && p != idp->top; new = p) {
238 p = p->ary[0];
239 new->ary[0] = NULL;
240 new->bitmap = new->count = 0;
Nadia Derbey4ae53782008-07-25 01:47:58 -0700241 __move_to_free_list(idp, new);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242 }
Roland Dreierc259cc22006-07-14 00:24:23 -0700243 spin_unlock_irqrestore(&idp->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244 return -1;
245 }
246 new->ary[0] = p;
247 new->count = 1;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800248 new->layer = layers-1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249 if (p->bitmap == IDR_FULL)
250 __set_bit(0, &new->bitmap);
251 p = new;
252 }
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700253 rcu_assign_pointer(idp->top, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254 idp->layers = layers;
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900255 v = sub_alloc(idp, &id, pa);
Nadia Derbey944ca052008-07-25 01:47:59 -0700256 if (v == IDR_NEED_TO_GROW)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257 goto build_up;
258 return(v);
259}
260
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900261static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id)
262{
263 struct idr_layer *pa[MAX_LEVEL];
264 int id;
265
266 id = idr_get_empty_slot(idp, starting_id, pa);
267 if (id >= 0) {
268 /*
269 * Successfully found an empty slot. Install the user
270 * pointer and mark the slot full.
271 */
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700272 rcu_assign_pointer(pa[0]->ary[id & IDR_MASK],
273 (struct idr_layer *)ptr);
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900274 pa[0]->count++;
275 idr_mark_full(pa, id);
276 }
277
278 return id;
279}
280
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281/**
John McCutchan7c657f22005-08-26 14:02:04 -0400282 * idr_get_new_above - allocate new idr entry above or equal to a start id
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 * @idp: idr handle
Thadeu Lima de Souza Cascardo94e2bd62009-10-16 15:20:49 +0200284 * @ptr: pointer you want associated with the id
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285 * @start_id: id to start search at
286 * @id: pointer to the allocated handle
287 *
288 * This is the allocate id function. It should be called with any
289 * required locks.
290 *
291 * If memory is required, it will return -EAGAIN, you should unlock
292 * and go back to the idr_pre_get() call. If the idr is full, it will
293 * return -ENOSPC.
294 *
Li Zefanb0981612009-01-15 13:51:00 -0800295 * @id returns a value in the range @starting_id ... 0x7fffffff
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 */
297int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id)
298{
299 int rv;
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800300
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 rv = idr_get_new_above_int(idp, ptr, starting_id);
302 /*
303 * This is a cheap hack until the IDR code can be fixed to
304 * return proper error values.
305 */
Nadia Derbey944ca052008-07-25 01:47:59 -0700306 if (rv < 0)
307 return _idr_rc_to_errno(rv);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308 *id = rv;
309 return 0;
310}
311EXPORT_SYMBOL(idr_get_new_above);
312
313/**
314 * idr_get_new - allocate new idr entry
315 * @idp: idr handle
Thadeu Lima de Souza Cascardo94e2bd62009-10-16 15:20:49 +0200316 * @ptr: pointer you want associated with the id
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317 * @id: pointer to the allocated handle
318 *
319 * This is the allocate id function. It should be called with any
320 * required locks.
321 *
322 * If memory is required, it will return -EAGAIN, you should unlock
323 * and go back to the idr_pre_get() call. If the idr is full, it will
324 * return -ENOSPC.
325 *
326 * @id returns a value in the range 0 ... 0x7fffffff
327 */
328int idr_get_new(struct idr *idp, void *ptr, int *id)
329{
330 int rv;
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800331
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332 rv = idr_get_new_above_int(idp, ptr, 0);
333 /*
334 * This is a cheap hack until the IDR code can be fixed to
335 * return proper error values.
336 */
Nadia Derbey944ca052008-07-25 01:47:59 -0700337 if (rv < 0)
338 return _idr_rc_to_errno(rv);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339 *id = rv;
340 return 0;
341}
342EXPORT_SYMBOL(idr_get_new);
343
344static void idr_remove_warning(int id)
345{
Nadia Derbeyf098ad62008-07-25 01:47:59 -0700346 printk(KERN_WARNING
347 "idr_remove called for id=%d which is not allocated.\n", id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348 dump_stack();
349}
350
351static void sub_remove(struct idr *idp, int shift, int id)
352{
353 struct idr_layer *p = idp->top;
354 struct idr_layer **pa[MAX_LEVEL];
355 struct idr_layer ***paa = &pa[0];
Nadia Derbeycf481c22008-07-25 01:48:02 -0700356 struct idr_layer *to_free;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357 int n;
358
359 *paa = NULL;
360 *++paa = &idp->top;
361
362 while ((shift > 0) && p) {
363 n = (id >> shift) & IDR_MASK;
364 __clear_bit(n, &p->bitmap);
365 *++paa = &p->ary[n];
366 p = p->ary[n];
367 shift -= IDR_BITS;
368 }
369 n = id & IDR_MASK;
370 if (likely(p != NULL && test_bit(n, &p->bitmap))){
371 __clear_bit(n, &p->bitmap);
Nadia Derbeycf481c22008-07-25 01:48:02 -0700372 rcu_assign_pointer(p->ary[n], NULL);
373 to_free = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374 while(*paa && ! --((**paa)->count)){
Nadia Derbeycf481c22008-07-25 01:48:02 -0700375 if (to_free)
376 free_layer(to_free);
377 to_free = **paa;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378 **paa-- = NULL;
379 }
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800380 if (!*paa)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381 idp->layers = 0;
Nadia Derbeycf481c22008-07-25 01:48:02 -0700382 if (to_free)
383 free_layer(to_free);
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800384 } else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385 idr_remove_warning(id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700386}
387
388/**
389 * idr_remove - remove the given id and free it's slot
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800390 * @idp: idr handle
391 * @id: unique key
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392 */
393void idr_remove(struct idr *idp, int id)
394{
395 struct idr_layer *p;
Nadia Derbeycf481c22008-07-25 01:48:02 -0700396 struct idr_layer *to_free;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397
398 /* Mask off upper bits we don't use for the search. */
399 id &= MAX_ID_MASK;
400
401 sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800402 if (idp->top && idp->top->count == 1 && (idp->layers > 1) &&
Nadia Derbeycf481c22008-07-25 01:48:02 -0700403 idp->top->ary[0]) {
404 /*
405 * Single child at leftmost slot: we can shrink the tree.
406 * This level is not needed anymore since when layers are
407 * inserted, they are inserted at the top of the existing
408 * tree.
409 */
410 to_free = idp->top;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411 p = idp->top->ary[0];
Nadia Derbeycf481c22008-07-25 01:48:02 -0700412 rcu_assign_pointer(idp->top, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 --idp->layers;
Nadia Derbeycf481c22008-07-25 01:48:02 -0700414 to_free->bitmap = to_free->count = 0;
415 free_layer(to_free);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 }
417 while (idp->id_free_cnt >= IDR_FREE_MAX) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700418 p = get_from_free_list(idp);
Nadia Derbeycf481c22008-07-25 01:48:02 -0700419 /*
420 * Note: we don't call the rcu callback here, since the only
421 * layers that fall into the freelist are those that have been
422 * preallocated.
423 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 kmem_cache_free(idr_layer_cache, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700425 }
Nadia Derbeyaf8e2a42008-05-01 04:34:57 -0700426 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427}
428EXPORT_SYMBOL(idr_remove);
429
430/**
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700431 * idr_remove_all - remove all ids from the given idr tree
432 * @idp: idr handle
433 *
434 * idr_destroy() only frees up unused, cached idp_layers, but this
435 * function will remove all id mappings and leave all idp_layers
436 * unused.
437 *
438 * A typical clean-up sequence for objects stored in an idr tree, will
439 * use idr_for_each() to free all objects, if necessay, then
440 * idr_remove_all() to remove all ids, and idr_destroy() to free
441 * up the cached idr_layers.
442 */
443void idr_remove_all(struct idr *idp)
444{
Oleg Nesterov6ace06d2007-07-31 00:39:19 -0700445 int n, id, max;
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700446 struct idr_layer *p;
447 struct idr_layer *pa[MAX_LEVEL];
448 struct idr_layer **paa = &pa[0];
449
450 n = idp->layers * IDR_BITS;
451 p = idp->top;
Paul E. McKenney1b233362009-03-10 12:55:52 -0700452 rcu_assign_pointer(idp->top, NULL);
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700453 max = 1 << n;
454
455 id = 0;
Oleg Nesterov6ace06d2007-07-31 00:39:19 -0700456 while (id < max) {
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700457 while (n > IDR_BITS && p) {
458 n -= IDR_BITS;
459 *paa++ = p;
460 p = p->ary[(id >> n) & IDR_MASK];
461 }
462
463 id += 1 << n;
464 while (n < fls(id)) {
Nadia Derbeycf481c22008-07-25 01:48:02 -0700465 if (p)
466 free_layer(p);
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700467 n += IDR_BITS;
468 p = *--paa;
469 }
470 }
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700471 idp->layers = 0;
472}
473EXPORT_SYMBOL(idr_remove_all);
474
475/**
Andrew Morton8d3b3592005-10-23 12:57:18 -0700476 * idr_destroy - release all cached layers within an idr tree
477 * idp: idr handle
478 */
479void idr_destroy(struct idr *idp)
480{
481 while (idp->id_free_cnt) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700482 struct idr_layer *p = get_from_free_list(idp);
Andrew Morton8d3b3592005-10-23 12:57:18 -0700483 kmem_cache_free(idr_layer_cache, p);
484 }
485}
486EXPORT_SYMBOL(idr_destroy);
487
488/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700489 * idr_find - return pointer for given id
490 * @idp: idr handle
491 * @id: lookup key
492 *
493 * Return the pointer given the id it has been registered with. A %NULL
494 * return indicates that @id is not valid or you passed %NULL in
495 * idr_get_new().
496 *
Nadia Derbeyf9c46d62008-07-25 01:48:01 -0700497 * This function can be called under rcu_read_lock(), given that the leaf
498 * pointers lifetimes are correctly managed.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700499 */
500void *idr_find(struct idr *idp, int id)
501{
502 int n;
503 struct idr_layer *p;
504
Nadia Derbeyf9c46d62008-07-25 01:48:01 -0700505 p = rcu_dereference(idp->top);
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800506 if (!p)
507 return NULL;
508 n = (p->layer+1) * IDR_BITS;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700509
510 /* Mask off upper bits we don't use for the search. */
511 id &= MAX_ID_MASK;
512
513 if (id >= (1 << n))
514 return NULL;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800515 BUG_ON(n == 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516
517 while (n > 0 && p) {
518 n -= IDR_BITS;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800519 BUG_ON(n != p->layer*IDR_BITS);
Nadia Derbeyf9c46d62008-07-25 01:48:01 -0700520 p = rcu_dereference(p->ary[(id >> n) & IDR_MASK]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521 }
522 return((void *)p);
523}
524EXPORT_SYMBOL(idr_find);
525
Jeff Mahoney5806f072006-06-26 00:27:19 -0700526/**
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700527 * idr_for_each - iterate through all stored pointers
528 * @idp: idr handle
529 * @fn: function to be called for each pointer
530 * @data: data passed back to callback function
531 *
532 * Iterate over the pointers registered with the given idr. The
533 * callback function will be called for each pointer currently
534 * registered, passing the id, the pointer and the data pointer passed
535 * to this function. It is not safe to modify the idr tree while in
536 * the callback, so functions such as idr_get_new and idr_remove are
537 * not allowed.
538 *
539 * We check the return of @fn each time. If it returns anything other
540 * than 0, we break out and return that value.
541 *
542 * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove().
543 */
544int idr_for_each(struct idr *idp,
545 int (*fn)(int id, void *p, void *data), void *data)
546{
547 int n, id, max, error = 0;
548 struct idr_layer *p;
549 struct idr_layer *pa[MAX_LEVEL];
550 struct idr_layer **paa = &pa[0];
551
552 n = idp->layers * IDR_BITS;
Nadia Derbeyf9c46d62008-07-25 01:48:01 -0700553 p = rcu_dereference(idp->top);
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700554 max = 1 << n;
555
556 id = 0;
557 while (id < max) {
558 while (n > 0 && p) {
559 n -= IDR_BITS;
560 *paa++ = p;
Nadia Derbeyf9c46d62008-07-25 01:48:01 -0700561 p = rcu_dereference(p->ary[(id >> n) & IDR_MASK]);
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700562 }
563
564 if (p) {
565 error = fn(id, (void *)p, data);
566 if (error)
567 break;
568 }
569
570 id += 1 << n;
571 while (n < fls(id)) {
572 n += IDR_BITS;
573 p = *--paa;
574 }
575 }
576
577 return error;
578}
579EXPORT_SYMBOL(idr_for_each);
580
581/**
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700582 * idr_get_next - lookup next object of id to given id.
583 * @idp: idr handle
584 * @id: pointer to lookup key
585 *
586 * Returns pointer to registered object with id, which is next number to
587 * given id.
588 */
589
590void *idr_get_next(struct idr *idp, int *nextidp)
591{
592 struct idr_layer *p, *pa[MAX_LEVEL];
593 struct idr_layer **paa = &pa[0];
594 int id = *nextidp;
595 int n, max;
596
597 /* find first ent */
598 n = idp->layers * IDR_BITS;
599 max = 1 << n;
600 p = rcu_dereference(idp->top);
601 if (!p)
602 return NULL;
603
604 while (id < max) {
605 while (n > 0 && p) {
606 n -= IDR_BITS;
607 *paa++ = p;
608 p = rcu_dereference(p->ary[(id >> n) & IDR_MASK]);
609 }
610
611 if (p) {
612 *nextidp = id;
613 return p;
614 }
615
616 id += 1 << n;
617 while (n < fls(id)) {
618 n += IDR_BITS;
619 p = *--paa;
620 }
621 }
622 return NULL;
623}
624
625
626
627/**
Jeff Mahoney5806f072006-06-26 00:27:19 -0700628 * idr_replace - replace pointer for given id
629 * @idp: idr handle
630 * @ptr: pointer you want associated with the id
631 * @id: lookup key
632 *
633 * Replace the pointer registered with an id and return the old value.
634 * A -ENOENT return indicates that @id was not found.
635 * A -EINVAL return indicates that @id was not within valid constraints.
636 *
Nadia Derbeycf481c22008-07-25 01:48:02 -0700637 * The caller must serialize with writers.
Jeff Mahoney5806f072006-06-26 00:27:19 -0700638 */
639void *idr_replace(struct idr *idp, void *ptr, int id)
640{
641 int n;
642 struct idr_layer *p, *old_p;
643
Jeff Mahoney5806f072006-06-26 00:27:19 -0700644 p = idp->top;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800645 if (!p)
646 return ERR_PTR(-EINVAL);
647
648 n = (p->layer+1) * IDR_BITS;
Jeff Mahoney5806f072006-06-26 00:27:19 -0700649
650 id &= MAX_ID_MASK;
651
652 if (id >= (1 << n))
653 return ERR_PTR(-EINVAL);
654
655 n -= IDR_BITS;
656 while ((n > 0) && p) {
657 p = p->ary[(id >> n) & IDR_MASK];
658 n -= IDR_BITS;
659 }
660
661 n = id & IDR_MASK;
662 if (unlikely(p == NULL || !test_bit(n, &p->bitmap)))
663 return ERR_PTR(-ENOENT);
664
665 old_p = p->ary[n];
Nadia Derbeycf481c22008-07-25 01:48:02 -0700666 rcu_assign_pointer(p->ary[n], ptr);
Jeff Mahoney5806f072006-06-26 00:27:19 -0700667
668 return old_p;
669}
670EXPORT_SYMBOL(idr_replace);
671
Akinobu Mita199f0ca2008-04-29 01:03:13 -0700672void __init idr_init_cache(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673{
Akinobu Mita199f0ca2008-04-29 01:03:13 -0700674 idr_layer_cache = kmem_cache_create("idr_layer_cache",
Andrew Morton5b019e92009-01-15 13:51:21 -0800675 sizeof(struct idr_layer), 0, SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676}
677
678/**
679 * idr_init - initialize idr handle
680 * @idp: idr handle
681 *
682 * This function is use to set up the handle (@idp) that you will pass
683 * to the rest of the functions.
684 */
685void idr_init(struct idr *idp)
686{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687 memset(idp, 0, sizeof(struct idr));
688 spin_lock_init(&idp->lock);
689}
690EXPORT_SYMBOL(idr_init);
Tejun Heo72dba582007-06-14 03:45:13 +0900691
692
693/*
694 * IDA - IDR based ID allocator
695 *
696 * this is id allocator without id -> pointer translation. Memory
697 * usage is much lower than full blown idr because each id only
698 * occupies a bit. ida uses a custom leaf node which contains
699 * IDA_BITMAP_BITS slots.
700 *
701 * 2007-04-25 written by Tejun Heo <htejun@gmail.com>
702 */
703
704static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap)
705{
706 unsigned long flags;
707
708 if (!ida->free_bitmap) {
709 spin_lock_irqsave(&ida->idr.lock, flags);
710 if (!ida->free_bitmap) {
711 ida->free_bitmap = bitmap;
712 bitmap = NULL;
713 }
714 spin_unlock_irqrestore(&ida->idr.lock, flags);
715 }
716
717 kfree(bitmap);
718}
719
720/**
721 * ida_pre_get - reserve resources for ida allocation
722 * @ida: ida handle
723 * @gfp_mask: memory allocation flag
724 *
725 * This function should be called prior to locking and calling the
726 * following function. It preallocates enough memory to satisfy the
727 * worst possible allocation.
728 *
729 * If the system is REALLY out of memory this function returns 0,
730 * otherwise 1.
731 */
732int ida_pre_get(struct ida *ida, gfp_t gfp_mask)
733{
734 /* allocate idr_layers */
735 if (!idr_pre_get(&ida->idr, gfp_mask))
736 return 0;
737
738 /* allocate free_bitmap */
739 if (!ida->free_bitmap) {
740 struct ida_bitmap *bitmap;
741
742 bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask);
743 if (!bitmap)
744 return 0;
745
746 free_bitmap(ida, bitmap);
747 }
748
749 return 1;
750}
751EXPORT_SYMBOL(ida_pre_get);
752
753/**
754 * ida_get_new_above - allocate new ID above or equal to a start id
755 * @ida: ida handle
756 * @staring_id: id to start search at
757 * @p_id: pointer to the allocated handle
758 *
759 * Allocate new ID above or equal to @ida. It should be called with
760 * any required locks.
761 *
762 * If memory is required, it will return -EAGAIN, you should unlock
763 * and go back to the ida_pre_get() call. If the ida is full, it will
764 * return -ENOSPC.
765 *
Li Zefanb0981612009-01-15 13:51:00 -0800766 * @p_id returns a value in the range @starting_id ... 0x7fffffff.
Tejun Heo72dba582007-06-14 03:45:13 +0900767 */
768int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
769{
770 struct idr_layer *pa[MAX_LEVEL];
771 struct ida_bitmap *bitmap;
772 unsigned long flags;
773 int idr_id = starting_id / IDA_BITMAP_BITS;
774 int offset = starting_id % IDA_BITMAP_BITS;
775 int t, id;
776
777 restart:
778 /* get vacant slot */
779 t = idr_get_empty_slot(&ida->idr, idr_id, pa);
Nadia Derbey944ca052008-07-25 01:47:59 -0700780 if (t < 0)
781 return _idr_rc_to_errno(t);
Tejun Heo72dba582007-06-14 03:45:13 +0900782
783 if (t * IDA_BITMAP_BITS >= MAX_ID_BIT)
784 return -ENOSPC;
785
786 if (t != idr_id)
787 offset = 0;
788 idr_id = t;
789
790 /* if bitmap isn't there, create a new one */
791 bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK];
792 if (!bitmap) {
793 spin_lock_irqsave(&ida->idr.lock, flags);
794 bitmap = ida->free_bitmap;
795 ida->free_bitmap = NULL;
796 spin_unlock_irqrestore(&ida->idr.lock, flags);
797
798 if (!bitmap)
799 return -EAGAIN;
800
801 memset(bitmap, 0, sizeof(struct ida_bitmap));
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700802 rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK],
803 (void *)bitmap);
Tejun Heo72dba582007-06-14 03:45:13 +0900804 pa[0]->count++;
805 }
806
807 /* lookup for empty slot */
808 t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset);
809 if (t == IDA_BITMAP_BITS) {
810 /* no empty slot after offset, continue to the next chunk */
811 idr_id++;
812 offset = 0;
813 goto restart;
814 }
815
816 id = idr_id * IDA_BITMAP_BITS + t;
817 if (id >= MAX_ID_BIT)
818 return -ENOSPC;
819
820 __set_bit(t, bitmap->bitmap);
821 if (++bitmap->nr_busy == IDA_BITMAP_BITS)
822 idr_mark_full(pa, idr_id);
823
824 *p_id = id;
825
826 /* Each leaf node can handle nearly a thousand slots and the
827 * whole idea of ida is to have small memory foot print.
828 * Throw away extra resources one by one after each successful
829 * allocation.
830 */
831 if (ida->idr.id_free_cnt || ida->free_bitmap) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700832 struct idr_layer *p = get_from_free_list(&ida->idr);
Tejun Heo72dba582007-06-14 03:45:13 +0900833 if (p)
834 kmem_cache_free(idr_layer_cache, p);
835 }
836
837 return 0;
838}
839EXPORT_SYMBOL(ida_get_new_above);
840
841/**
842 * ida_get_new - allocate new ID
843 * @ida: idr handle
844 * @p_id: pointer to the allocated handle
845 *
846 * Allocate new ID. It should be called with any required locks.
847 *
848 * If memory is required, it will return -EAGAIN, you should unlock
849 * and go back to the idr_pre_get() call. If the idr is full, it will
850 * return -ENOSPC.
851 *
852 * @id returns a value in the range 0 ... 0x7fffffff.
853 */
854int ida_get_new(struct ida *ida, int *p_id)
855{
856 return ida_get_new_above(ida, 0, p_id);
857}
858EXPORT_SYMBOL(ida_get_new);
859
860/**
861 * ida_remove - remove the given ID
862 * @ida: ida handle
863 * @id: ID to free
864 */
865void ida_remove(struct ida *ida, int id)
866{
867 struct idr_layer *p = ida->idr.top;
868 int shift = (ida->idr.layers - 1) * IDR_BITS;
869 int idr_id = id / IDA_BITMAP_BITS;
870 int offset = id % IDA_BITMAP_BITS;
871 int n;
872 struct ida_bitmap *bitmap;
873
874 /* clear full bits while looking up the leaf idr_layer */
875 while ((shift > 0) && p) {
876 n = (idr_id >> shift) & IDR_MASK;
877 __clear_bit(n, &p->bitmap);
878 p = p->ary[n];
879 shift -= IDR_BITS;
880 }
881
882 if (p == NULL)
883 goto err;
884
885 n = idr_id & IDR_MASK;
886 __clear_bit(n, &p->bitmap);
887
888 bitmap = (void *)p->ary[n];
889 if (!test_bit(offset, bitmap->bitmap))
890 goto err;
891
892 /* update bitmap and remove it if empty */
893 __clear_bit(offset, bitmap->bitmap);
894 if (--bitmap->nr_busy == 0) {
895 __set_bit(n, &p->bitmap); /* to please idr_remove() */
896 idr_remove(&ida->idr, idr_id);
897 free_bitmap(ida, bitmap);
898 }
899
900 return;
901
902 err:
903 printk(KERN_WARNING
904 "ida_remove called for id=%d which is not allocated.\n", id);
905}
906EXPORT_SYMBOL(ida_remove);
907
908/**
909 * ida_destroy - release all cached layers within an ida tree
910 * ida: ida handle
911 */
912void ida_destroy(struct ida *ida)
913{
914 idr_destroy(&ida->idr);
915 kfree(ida->free_bitmap);
916}
917EXPORT_SYMBOL(ida_destroy);
918
919/**
920 * ida_init - initialize ida handle
921 * @ida: ida handle
922 *
923 * This function is use to set up the handle (@ida) that you will pass
924 * to the rest of the functions.
925 */
926void ida_init(struct ida *ida)
927{
928 memset(ida, 0, sizeof(struct ida));
929 idr_init(&ida->idr);
930
931}
932EXPORT_SYMBOL(ida_init);