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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 */
Tejun Heod2e72762010-02-22 12:44:19 -0800159 if (id >= 1 << (idp->layers * IDR_BITS)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160 *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 Heod2e72762010-02-22 12:44:19 -0800163 p = pa[l];
164 BUG_ON(!p);
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900165
166 /* If we need to go up one layer, continue the
167 * loop; otherwise, restart from the top.
168 */
169 sh = IDR_BITS * (l + 1);
170 if (oid >> sh == id >> sh)
171 continue;
172 else
173 goto restart;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174 }
175 if (m != n) {
176 sh = IDR_BITS*l;
177 id = ((id >> sh) ^ n ^ m) << sh;
178 }
179 if ((id >= MAX_ID_BIT) || (id < 0))
Nadia Derbey944ca052008-07-25 01:47:59 -0700180 return IDR_NOMORE_SPACE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181 if (l == 0)
182 break;
183 /*
184 * Create the layer below if it is missing.
185 */
186 if (!p->ary[m]) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700187 new = get_from_free_list(idp);
188 if (!new)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 return -1;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800190 new->layer = l-1;
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700191 rcu_assign_pointer(p->ary[m], new);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192 p->count++;
193 }
194 pa[l--] = p;
195 p = p->ary[m];
196 }
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900197
198 pa[l] = p;
199 return id;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200}
201
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900202static int idr_get_empty_slot(struct idr *idp, int starting_id,
203 struct idr_layer **pa)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204{
205 struct idr_layer *p, *new;
206 int layers, v, id;
Roland Dreierc259cc22006-07-14 00:24:23 -0700207 unsigned long flags;
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800208
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 id = starting_id;
210build_up:
211 p = idp->top;
212 layers = idp->layers;
213 if (unlikely(!p)) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700214 if (!(p = get_from_free_list(idp)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215 return -1;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800216 p->layer = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217 layers = 1;
218 }
219 /*
220 * Add a new layer to the top of the tree if the requested
221 * id is larger than the currently allocated space.
222 */
Zaur Kambarov589777e2005-06-21 17:14:31 -0700223 while ((layers < (MAX_LEVEL - 1)) && (id >= (1 << (layers*IDR_BITS)))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224 layers++;
Manfred Spraul711a49a2008-12-10 18:17:06 +0100225 if (!p->count) {
226 /* special case: if the tree is currently empty,
227 * then we grow the tree by moving the top node
228 * upwards.
229 */
230 p->layer++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231 continue;
Manfred Spraul711a49a2008-12-10 18:17:06 +0100232 }
Nadia Derbey4ae53782008-07-25 01:47:58 -0700233 if (!(new = get_from_free_list(idp))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234 /*
235 * The allocation failed. If we built part of
236 * the structure tear it down.
237 */
Roland Dreierc259cc22006-07-14 00:24:23 -0700238 spin_lock_irqsave(&idp->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239 for (new = p; p && p != idp->top; new = p) {
240 p = p->ary[0];
241 new->ary[0] = NULL;
242 new->bitmap = new->count = 0;
Nadia Derbey4ae53782008-07-25 01:47:58 -0700243 __move_to_free_list(idp, new);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244 }
Roland Dreierc259cc22006-07-14 00:24:23 -0700245 spin_unlock_irqrestore(&idp->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246 return -1;
247 }
248 new->ary[0] = p;
249 new->count = 1;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800250 new->layer = layers-1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251 if (p->bitmap == IDR_FULL)
252 __set_bit(0, &new->bitmap);
253 p = new;
254 }
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700255 rcu_assign_pointer(idp->top, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 idp->layers = layers;
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900257 v = sub_alloc(idp, &id, pa);
Nadia Derbey944ca052008-07-25 01:47:59 -0700258 if (v == IDR_NEED_TO_GROW)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259 goto build_up;
260 return(v);
261}
262
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900263static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id)
264{
265 struct idr_layer *pa[MAX_LEVEL];
266 int id;
267
268 id = idr_get_empty_slot(idp, starting_id, pa);
269 if (id >= 0) {
270 /*
271 * Successfully found an empty slot. Install the user
272 * pointer and mark the slot full.
273 */
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700274 rcu_assign_pointer(pa[0]->ary[id & IDR_MASK],
275 (struct idr_layer *)ptr);
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900276 pa[0]->count++;
277 idr_mark_full(pa, id);
278 }
279
280 return id;
281}
282
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283/**
John McCutchan7c657f22005-08-26 14:02:04 -0400284 * idr_get_new_above - allocate new idr entry above or equal to a start id
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285 * @idp: idr handle
Thadeu Lima de Souza Cascardo94e2bd62009-10-16 15:20:49 +0200286 * @ptr: pointer you want associated with the id
Naohiro Aotaea24ea82010-08-31 00:37:03 +0900287 * @starting_id: id to start search at
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288 * @id: pointer to the allocated handle
289 *
290 * This is the allocate id function. It should be called with any
291 * required locks.
292 *
293 * If memory is required, it will return -EAGAIN, you should unlock
294 * and go back to the idr_pre_get() call. If the idr is full, it will
295 * return -ENOSPC.
296 *
Li Zefanb0981612009-01-15 13:51:00 -0800297 * @id returns a value in the range @starting_id ... 0x7fffffff
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298 */
299int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id)
300{
301 int rv;
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800302
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 rv = idr_get_new_above_int(idp, ptr, starting_id);
304 /*
305 * This is a cheap hack until the IDR code can be fixed to
306 * return proper error values.
307 */
Nadia Derbey944ca052008-07-25 01:47:59 -0700308 if (rv < 0)
309 return _idr_rc_to_errno(rv);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 *id = rv;
311 return 0;
312}
313EXPORT_SYMBOL(idr_get_new_above);
314
315/**
316 * idr_get_new - allocate new idr entry
317 * @idp: idr handle
Thadeu Lima de Souza Cascardo94e2bd62009-10-16 15:20:49 +0200318 * @ptr: pointer you want associated with the id
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319 * @id: pointer to the allocated handle
320 *
321 * This is the allocate id function. It should be called with any
322 * required locks.
323 *
324 * If memory is required, it will return -EAGAIN, you should unlock
325 * and go back to the idr_pre_get() call. If the idr is full, it will
326 * return -ENOSPC.
327 *
328 * @id returns a value in the range 0 ... 0x7fffffff
329 */
330int idr_get_new(struct idr *idp, void *ptr, int *id)
331{
332 int rv;
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800333
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334 rv = idr_get_new_above_int(idp, ptr, 0);
335 /*
336 * This is a cheap hack until the IDR code can be fixed to
337 * return proper error values.
338 */
Nadia Derbey944ca052008-07-25 01:47:59 -0700339 if (rv < 0)
340 return _idr_rc_to_errno(rv);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341 *id = rv;
342 return 0;
343}
344EXPORT_SYMBOL(idr_get_new);
345
346static void idr_remove_warning(int id)
347{
Nadia Derbeyf098ad62008-07-25 01:47:59 -0700348 printk(KERN_WARNING
349 "idr_remove called for id=%d which is not allocated.\n", id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 dump_stack();
351}
352
353static void sub_remove(struct idr *idp, int shift, int id)
354{
355 struct idr_layer *p = idp->top;
356 struct idr_layer **pa[MAX_LEVEL];
357 struct idr_layer ***paa = &pa[0];
Nadia Derbeycf481c22008-07-25 01:48:02 -0700358 struct idr_layer *to_free;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359 int n;
360
361 *paa = NULL;
362 *++paa = &idp->top;
363
364 while ((shift > 0) && p) {
365 n = (id >> shift) & IDR_MASK;
366 __clear_bit(n, &p->bitmap);
367 *++paa = &p->ary[n];
368 p = p->ary[n];
369 shift -= IDR_BITS;
370 }
371 n = id & IDR_MASK;
372 if (likely(p != NULL && test_bit(n, &p->bitmap))){
373 __clear_bit(n, &p->bitmap);
Nadia Derbeycf481c22008-07-25 01:48:02 -0700374 rcu_assign_pointer(p->ary[n], NULL);
375 to_free = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376 while(*paa && ! --((**paa)->count)){
Nadia Derbeycf481c22008-07-25 01:48:02 -0700377 if (to_free)
378 free_layer(to_free);
379 to_free = **paa;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380 **paa-- = NULL;
381 }
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800382 if (!*paa)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383 idp->layers = 0;
Nadia Derbeycf481c22008-07-25 01:48:02 -0700384 if (to_free)
385 free_layer(to_free);
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800386 } else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387 idr_remove_warning(id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388}
389
390/**
391 * idr_remove - remove the given id and free it's slot
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800392 * @idp: idr handle
393 * @id: unique key
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 */
395void idr_remove(struct idr *idp, int id)
396{
397 struct idr_layer *p;
Nadia Derbeycf481c22008-07-25 01:48:02 -0700398 struct idr_layer *to_free;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399
400 /* Mask off upper bits we don't use for the search. */
401 id &= MAX_ID_MASK;
402
403 sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800404 if (idp->top && idp->top->count == 1 && (idp->layers > 1) &&
Nadia Derbeycf481c22008-07-25 01:48:02 -0700405 idp->top->ary[0]) {
406 /*
407 * Single child at leftmost slot: we can shrink the tree.
408 * This level is not needed anymore since when layers are
409 * inserted, they are inserted at the top of the existing
410 * tree.
411 */
412 to_free = idp->top;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 p = idp->top->ary[0];
Nadia Derbeycf481c22008-07-25 01:48:02 -0700414 rcu_assign_pointer(idp->top, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 --idp->layers;
Nadia Derbeycf481c22008-07-25 01:48:02 -0700416 to_free->bitmap = to_free->count = 0;
417 free_layer(to_free);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 }
419 while (idp->id_free_cnt >= IDR_FREE_MAX) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700420 p = get_from_free_list(idp);
Nadia Derbeycf481c22008-07-25 01:48:02 -0700421 /*
422 * Note: we don't call the rcu callback here, since the only
423 * layers that fall into the freelist are those that have been
424 * preallocated.
425 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426 kmem_cache_free(idr_layer_cache, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 }
Nadia Derbeyaf8e2a42008-05-01 04:34:57 -0700428 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429}
430EXPORT_SYMBOL(idr_remove);
431
432/**
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700433 * idr_remove_all - remove all ids from the given idr tree
434 * @idp: idr handle
435 *
436 * idr_destroy() only frees up unused, cached idp_layers, but this
437 * function will remove all id mappings and leave all idp_layers
438 * unused.
439 *
440 * A typical clean-up sequence for objects stored in an idr tree, will
441 * use idr_for_each() to free all objects, if necessay, then
442 * idr_remove_all() to remove all ids, and idr_destroy() to free
443 * up the cached idr_layers.
444 */
445void idr_remove_all(struct idr *idp)
446{
Oleg Nesterov6ace06dc2007-07-31 00:39:19 -0700447 int n, id, max;
Imre Deak2dcb22b2010-05-26 14:43:38 -0700448 int bt_mask;
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700449 struct idr_layer *p;
450 struct idr_layer *pa[MAX_LEVEL];
451 struct idr_layer **paa = &pa[0];
452
453 n = idp->layers * IDR_BITS;
454 p = idp->top;
Paul E. McKenney1b233362009-03-10 12:55:52 -0700455 rcu_assign_pointer(idp->top, NULL);
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700456 max = 1 << n;
457
458 id = 0;
Oleg Nesterov6ace06dc2007-07-31 00:39:19 -0700459 while (id < max) {
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700460 while (n > IDR_BITS && p) {
461 n -= IDR_BITS;
462 *paa++ = p;
463 p = p->ary[(id >> n) & IDR_MASK];
464 }
465
Imre Deak2dcb22b2010-05-26 14:43:38 -0700466 bt_mask = id;
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700467 id += 1 << n;
Imre Deak2dcb22b2010-05-26 14:43:38 -0700468 /* Get the highest bit that the above add changed from 0->1. */
469 while (n < fls(id ^ bt_mask)) {
Nadia Derbeycf481c22008-07-25 01:48:02 -0700470 if (p)
471 free_layer(p);
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700472 n += IDR_BITS;
473 p = *--paa;
474 }
475 }
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700476 idp->layers = 0;
477}
478EXPORT_SYMBOL(idr_remove_all);
479
480/**
Andrew Morton8d3b3592005-10-23 12:57:18 -0700481 * idr_destroy - release all cached layers within an idr tree
Naohiro Aotaea24ea82010-08-31 00:37:03 +0900482 * @idp: idr handle
Andrew Morton8d3b3592005-10-23 12:57:18 -0700483 */
484void idr_destroy(struct idr *idp)
485{
486 while (idp->id_free_cnt) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700487 struct idr_layer *p = get_from_free_list(idp);
Andrew Morton8d3b3592005-10-23 12:57:18 -0700488 kmem_cache_free(idr_layer_cache, p);
489 }
490}
491EXPORT_SYMBOL(idr_destroy);
492
493/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494 * idr_find - return pointer for given id
495 * @idp: idr handle
496 * @id: lookup key
497 *
498 * Return the pointer given the id it has been registered with. A %NULL
499 * return indicates that @id is not valid or you passed %NULL in
500 * idr_get_new().
501 *
Nadia Derbeyf9c46d62008-07-25 01:48:01 -0700502 * This function can be called under rcu_read_lock(), given that the leaf
503 * pointers lifetimes are correctly managed.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504 */
505void *idr_find(struct idr *idp, int id)
506{
507 int n;
508 struct idr_layer *p;
509
Paul E. McKenney96be7532010-02-22 17:04:55 -0800510 p = rcu_dereference_raw(idp->top);
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800511 if (!p)
512 return NULL;
513 n = (p->layer+1) * IDR_BITS;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514
515 /* Mask off upper bits we don't use for the search. */
516 id &= MAX_ID_MASK;
517
518 if (id >= (1 << n))
519 return NULL;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800520 BUG_ON(n == 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521
522 while (n > 0 && p) {
523 n -= IDR_BITS;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800524 BUG_ON(n != p->layer*IDR_BITS);
Paul E. McKenney96be7532010-02-22 17:04:55 -0800525 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526 }
527 return((void *)p);
528}
529EXPORT_SYMBOL(idr_find);
530
Jeff Mahoney5806f072006-06-26 00:27:19 -0700531/**
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700532 * idr_for_each - iterate through all stored pointers
533 * @idp: idr handle
534 * @fn: function to be called for each pointer
535 * @data: data passed back to callback function
536 *
537 * Iterate over the pointers registered with the given idr. The
538 * callback function will be called for each pointer currently
539 * registered, passing the id, the pointer and the data pointer passed
540 * to this function. It is not safe to modify the idr tree while in
541 * the callback, so functions such as idr_get_new and idr_remove are
542 * not allowed.
543 *
544 * We check the return of @fn each time. If it returns anything other
545 * than 0, we break out and return that value.
546 *
547 * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove().
548 */
549int idr_for_each(struct idr *idp,
550 int (*fn)(int id, void *p, void *data), void *data)
551{
552 int n, id, max, error = 0;
553 struct idr_layer *p;
554 struct idr_layer *pa[MAX_LEVEL];
555 struct idr_layer **paa = &pa[0];
556
557 n = idp->layers * IDR_BITS;
Paul E. McKenney96be7532010-02-22 17:04:55 -0800558 p = rcu_dereference_raw(idp->top);
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700559 max = 1 << n;
560
561 id = 0;
562 while (id < max) {
563 while (n > 0 && p) {
564 n -= IDR_BITS;
565 *paa++ = p;
Paul E. McKenney96be7532010-02-22 17:04:55 -0800566 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700567 }
568
569 if (p) {
570 error = fn(id, (void *)p, data);
571 if (error)
572 break;
573 }
574
575 id += 1 << n;
576 while (n < fls(id)) {
577 n += IDR_BITS;
578 p = *--paa;
579 }
580 }
581
582 return error;
583}
584EXPORT_SYMBOL(idr_for_each);
585
586/**
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700587 * idr_get_next - lookup next object of id to given id.
588 * @idp: idr handle
Naohiro Aotaea24ea82010-08-31 00:37:03 +0900589 * @nextidp: pointer to lookup key
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700590 *
591 * Returns pointer to registered object with id, which is next number to
Naohiro Aota1458ce12010-08-27 17:43:46 +0900592 * given id. After being looked up, *@nextidp will be updated for the next
593 * iteration.
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700594 */
595
596void *idr_get_next(struct idr *idp, int *nextidp)
597{
598 struct idr_layer *p, *pa[MAX_LEVEL];
599 struct idr_layer **paa = &pa[0];
600 int id = *nextidp;
601 int n, max;
602
603 /* find first ent */
604 n = idp->layers * IDR_BITS;
605 max = 1 << n;
Paul E. McKenney94bfa3b2010-06-07 17:09:45 -0700606 p = rcu_dereference_raw(idp->top);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700607 if (!p)
608 return NULL;
609
610 while (id < max) {
611 while (n > 0 && p) {
612 n -= IDR_BITS;
613 *paa++ = p;
Paul E. McKenney94bfa3b2010-06-07 17:09:45 -0700614 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700615 }
616
617 if (p) {
618 *nextidp = id;
619 return p;
620 }
621
622 id += 1 << n;
623 while (n < fls(id)) {
624 n += IDR_BITS;
625 p = *--paa;
626 }
627 }
628 return NULL;
629}
Ben Hutchings4d1ee802010-01-29 20:59:17 +0000630EXPORT_SYMBOL(idr_get_next);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700631
632
633/**
Jeff Mahoney5806f072006-06-26 00:27:19 -0700634 * idr_replace - replace pointer for given id
635 * @idp: idr handle
636 * @ptr: pointer you want associated with the id
637 * @id: lookup key
638 *
639 * Replace the pointer registered with an id and return the old value.
640 * A -ENOENT return indicates that @id was not found.
641 * A -EINVAL return indicates that @id was not within valid constraints.
642 *
Nadia Derbeycf481c22008-07-25 01:48:02 -0700643 * The caller must serialize with writers.
Jeff Mahoney5806f072006-06-26 00:27:19 -0700644 */
645void *idr_replace(struct idr *idp, void *ptr, int id)
646{
647 int n;
648 struct idr_layer *p, *old_p;
649
Jeff Mahoney5806f072006-06-26 00:27:19 -0700650 p = idp->top;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800651 if (!p)
652 return ERR_PTR(-EINVAL);
653
654 n = (p->layer+1) * IDR_BITS;
Jeff Mahoney5806f072006-06-26 00:27:19 -0700655
656 id &= MAX_ID_MASK;
657
658 if (id >= (1 << n))
659 return ERR_PTR(-EINVAL);
660
661 n -= IDR_BITS;
662 while ((n > 0) && p) {
663 p = p->ary[(id >> n) & IDR_MASK];
664 n -= IDR_BITS;
665 }
666
667 n = id & IDR_MASK;
668 if (unlikely(p == NULL || !test_bit(n, &p->bitmap)))
669 return ERR_PTR(-ENOENT);
670
671 old_p = p->ary[n];
Nadia Derbeycf481c22008-07-25 01:48:02 -0700672 rcu_assign_pointer(p->ary[n], ptr);
Jeff Mahoney5806f072006-06-26 00:27:19 -0700673
674 return old_p;
675}
676EXPORT_SYMBOL(idr_replace);
677
Akinobu Mita199f0ca2008-04-29 01:03:13 -0700678void __init idr_init_cache(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679{
Akinobu Mita199f0ca2008-04-29 01:03:13 -0700680 idr_layer_cache = kmem_cache_create("idr_layer_cache",
Andrew Morton5b019e92009-01-15 13:51:21 -0800681 sizeof(struct idr_layer), 0, SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682}
683
684/**
685 * idr_init - initialize idr handle
686 * @idp: idr handle
687 *
688 * This function is use to set up the handle (@idp) that you will pass
689 * to the rest of the functions.
690 */
691void idr_init(struct idr *idp)
692{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693 memset(idp, 0, sizeof(struct idr));
694 spin_lock_init(&idp->lock);
695}
696EXPORT_SYMBOL(idr_init);
Tejun Heo72dba582007-06-14 03:45:13 +0900697
698
699/*
700 * IDA - IDR based ID allocator
701 *
702 * this is id allocator without id -> pointer translation. Memory
703 * usage is much lower than full blown idr because each id only
704 * occupies a bit. ida uses a custom leaf node which contains
705 * IDA_BITMAP_BITS slots.
706 *
707 * 2007-04-25 written by Tejun Heo <htejun@gmail.com>
708 */
709
710static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap)
711{
712 unsigned long flags;
713
714 if (!ida->free_bitmap) {
715 spin_lock_irqsave(&ida->idr.lock, flags);
716 if (!ida->free_bitmap) {
717 ida->free_bitmap = bitmap;
718 bitmap = NULL;
719 }
720 spin_unlock_irqrestore(&ida->idr.lock, flags);
721 }
722
723 kfree(bitmap);
724}
725
726/**
727 * ida_pre_get - reserve resources for ida allocation
728 * @ida: ida handle
729 * @gfp_mask: memory allocation flag
730 *
731 * This function should be called prior to locking and calling the
732 * following function. It preallocates enough memory to satisfy the
733 * worst possible allocation.
734 *
735 * If the system is REALLY out of memory this function returns 0,
736 * otherwise 1.
737 */
738int ida_pre_get(struct ida *ida, gfp_t gfp_mask)
739{
740 /* allocate idr_layers */
741 if (!idr_pre_get(&ida->idr, gfp_mask))
742 return 0;
743
744 /* allocate free_bitmap */
745 if (!ida->free_bitmap) {
746 struct ida_bitmap *bitmap;
747
748 bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask);
749 if (!bitmap)
750 return 0;
751
752 free_bitmap(ida, bitmap);
753 }
754
755 return 1;
756}
757EXPORT_SYMBOL(ida_pre_get);
758
759/**
760 * ida_get_new_above - allocate new ID above or equal to a start id
761 * @ida: ida handle
Naohiro Aotaea24ea82010-08-31 00:37:03 +0900762 * @starting_id: id to start search at
Tejun Heo72dba582007-06-14 03:45:13 +0900763 * @p_id: pointer to the allocated handle
764 *
765 * Allocate new ID above or equal to @ida. It should be called with
766 * any required locks.
767 *
768 * If memory is required, it will return -EAGAIN, you should unlock
769 * and go back to the ida_pre_get() call. If the ida is full, it will
770 * return -ENOSPC.
771 *
Li Zefanb0981612009-01-15 13:51:00 -0800772 * @p_id returns a value in the range @starting_id ... 0x7fffffff.
Tejun Heo72dba582007-06-14 03:45:13 +0900773 */
774int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
775{
776 struct idr_layer *pa[MAX_LEVEL];
777 struct ida_bitmap *bitmap;
778 unsigned long flags;
779 int idr_id = starting_id / IDA_BITMAP_BITS;
780 int offset = starting_id % IDA_BITMAP_BITS;
781 int t, id;
782
783 restart:
784 /* get vacant slot */
785 t = idr_get_empty_slot(&ida->idr, idr_id, pa);
Nadia Derbey944ca052008-07-25 01:47:59 -0700786 if (t < 0)
787 return _idr_rc_to_errno(t);
Tejun Heo72dba582007-06-14 03:45:13 +0900788
789 if (t * IDA_BITMAP_BITS >= MAX_ID_BIT)
790 return -ENOSPC;
791
792 if (t != idr_id)
793 offset = 0;
794 idr_id = t;
795
796 /* if bitmap isn't there, create a new one */
797 bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK];
798 if (!bitmap) {
799 spin_lock_irqsave(&ida->idr.lock, flags);
800 bitmap = ida->free_bitmap;
801 ida->free_bitmap = NULL;
802 spin_unlock_irqrestore(&ida->idr.lock, flags);
803
804 if (!bitmap)
805 return -EAGAIN;
806
807 memset(bitmap, 0, sizeof(struct ida_bitmap));
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700808 rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK],
809 (void *)bitmap);
Tejun Heo72dba582007-06-14 03:45:13 +0900810 pa[0]->count++;
811 }
812
813 /* lookup for empty slot */
814 t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset);
815 if (t == IDA_BITMAP_BITS) {
816 /* no empty slot after offset, continue to the next chunk */
817 idr_id++;
818 offset = 0;
819 goto restart;
820 }
821
822 id = idr_id * IDA_BITMAP_BITS + t;
823 if (id >= MAX_ID_BIT)
824 return -ENOSPC;
825
826 __set_bit(t, bitmap->bitmap);
827 if (++bitmap->nr_busy == IDA_BITMAP_BITS)
828 idr_mark_full(pa, idr_id);
829
830 *p_id = id;
831
832 /* Each leaf node can handle nearly a thousand slots and the
833 * whole idea of ida is to have small memory foot print.
834 * Throw away extra resources one by one after each successful
835 * allocation.
836 */
837 if (ida->idr.id_free_cnt || ida->free_bitmap) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700838 struct idr_layer *p = get_from_free_list(&ida->idr);
Tejun Heo72dba582007-06-14 03:45:13 +0900839 if (p)
840 kmem_cache_free(idr_layer_cache, p);
841 }
842
843 return 0;
844}
845EXPORT_SYMBOL(ida_get_new_above);
846
847/**
848 * ida_get_new - allocate new ID
849 * @ida: idr handle
850 * @p_id: pointer to the allocated handle
851 *
852 * Allocate new ID. It should be called with any required locks.
853 *
854 * If memory is required, it will return -EAGAIN, you should unlock
855 * and go back to the idr_pre_get() call. If the idr is full, it will
856 * return -ENOSPC.
857 *
858 * @id returns a value in the range 0 ... 0x7fffffff.
859 */
860int ida_get_new(struct ida *ida, int *p_id)
861{
862 return ida_get_new_above(ida, 0, p_id);
863}
864EXPORT_SYMBOL(ida_get_new);
865
866/**
867 * ida_remove - remove the given ID
868 * @ida: ida handle
869 * @id: ID to free
870 */
871void ida_remove(struct ida *ida, int id)
872{
873 struct idr_layer *p = ida->idr.top;
874 int shift = (ida->idr.layers - 1) * IDR_BITS;
875 int idr_id = id / IDA_BITMAP_BITS;
876 int offset = id % IDA_BITMAP_BITS;
877 int n;
878 struct ida_bitmap *bitmap;
879
880 /* clear full bits while looking up the leaf idr_layer */
881 while ((shift > 0) && p) {
882 n = (idr_id >> shift) & IDR_MASK;
883 __clear_bit(n, &p->bitmap);
884 p = p->ary[n];
885 shift -= IDR_BITS;
886 }
887
888 if (p == NULL)
889 goto err;
890
891 n = idr_id & IDR_MASK;
892 __clear_bit(n, &p->bitmap);
893
894 bitmap = (void *)p->ary[n];
895 if (!test_bit(offset, bitmap->bitmap))
896 goto err;
897
898 /* update bitmap and remove it if empty */
899 __clear_bit(offset, bitmap->bitmap);
900 if (--bitmap->nr_busy == 0) {
901 __set_bit(n, &p->bitmap); /* to please idr_remove() */
902 idr_remove(&ida->idr, idr_id);
903 free_bitmap(ida, bitmap);
904 }
905
906 return;
907
908 err:
909 printk(KERN_WARNING
910 "ida_remove called for id=%d which is not allocated.\n", id);
911}
912EXPORT_SYMBOL(ida_remove);
913
914/**
915 * ida_destroy - release all cached layers within an ida tree
Naohiro Aotaea24ea82010-08-31 00:37:03 +0900916 * @ida: ida handle
Tejun Heo72dba582007-06-14 03:45:13 +0900917 */
918void ida_destroy(struct ida *ida)
919{
920 idr_destroy(&ida->idr);
921 kfree(ida->free_bitmap);
922}
923EXPORT_SYMBOL(ida_destroy);
924
925/**
926 * ida_init - initialize ida handle
927 * @ida: ida handle
928 *
929 * This function is use to set up the handle (@ida) that you will pass
930 * to the rest of the functions.
931 */
932void ida_init(struct ida *ida)
933{
934 memset(ida, 0, sizeof(struct ida));
935 idr_init(&ida->idr);
936
937}
938EXPORT_SYMBOL(ida_init);