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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.
Linus Torvalds1da177e2005-04-16 15:20:36 -070021 */
22
23#ifndef TEST // to test in user space...
24#include <linux/slab.h>
25#include <linux/init.h>
Paul Gortmaker8bc3bcc2011-11-16 21:29:17 -050026#include <linux/export.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070027#endif
Jeff Mahoney5806f072006-06-26 00:27:19 -070028#include <linux/err.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#include <linux/string.h>
30#include <linux/idr.h>
Rusty Russell88eca022011-08-03 16:21:06 -070031#include <linux/spinlock.h>
Tejun Heod5c74092013-02-27 17:03:55 -080032#include <linux/percpu.h>
33#include <linux/hardirq.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070034
Tejun Heoe8c8d1b2013-02-27 17:05:04 -080035#define MAX_IDR_SHIFT (sizeof(int) * 8 - 1)
36#define MAX_IDR_BIT (1U << MAX_IDR_SHIFT)
37
38/* Leave the possibility of an incomplete final layer */
39#define MAX_IDR_LEVEL ((MAX_IDR_SHIFT + IDR_BITS - 1) / IDR_BITS)
40
41/* Number of id_layer structs to leave in free list */
42#define MAX_IDR_FREE (MAX_IDR_LEVEL * 2)
43
Christoph Lametere18b8902006-12-06 20:33:20 -080044static struct kmem_cache *idr_layer_cache;
Tejun Heod5c74092013-02-27 17:03:55 -080045static DEFINE_PER_CPU(struct idr_layer *, idr_preload_head);
46static DEFINE_PER_CPU(int, idr_preload_cnt);
Rusty Russell88eca022011-08-03 16:21:06 -070047static DEFINE_SPINLOCK(simple_ida_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070048
Tejun Heo326cf0f2013-02-27 17:05:02 -080049/* the maximum ID which can be allocated given idr->layers */
50static int idr_max(int layers)
51{
52 int bits = min_t(int, layers * IDR_BITS, MAX_IDR_SHIFT);
53
54 return (1 << bits) - 1;
55}
56
Tejun Heo54616282013-02-27 17:05:07 -080057/*
58 * Prefix mask for an idr_layer at @layer. For layer 0, the prefix mask is
59 * all bits except for the lower IDR_BITS. For layer 1, 2 * IDR_BITS, and
60 * so on.
61 */
62static int idr_layer_prefix_mask(int layer)
63{
64 return ~idr_max(layer + 1);
65}
66
Nadia Derbey4ae53782008-07-25 01:47:58 -070067static struct idr_layer *get_from_free_list(struct idr *idp)
Linus Torvalds1da177e2005-04-16 15:20:36 -070068{
69 struct idr_layer *p;
Roland Dreierc259cc22006-07-14 00:24:23 -070070 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -070071
Roland Dreierc259cc22006-07-14 00:24:23 -070072 spin_lock_irqsave(&idp->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -070073 if ((p = idp->id_free)) {
74 idp->id_free = p->ary[0];
75 idp->id_free_cnt--;
76 p->ary[0] = NULL;
77 }
Roland Dreierc259cc22006-07-14 00:24:23 -070078 spin_unlock_irqrestore(&idp->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -070079 return(p);
80}
81
Tejun Heod5c74092013-02-27 17:03:55 -080082/**
83 * idr_layer_alloc - allocate a new idr_layer
84 * @gfp_mask: allocation mask
85 * @layer_idr: optional idr to allocate from
86 *
87 * If @layer_idr is %NULL, directly allocate one using @gfp_mask or fetch
88 * one from the per-cpu preload buffer. If @layer_idr is not %NULL, fetch
89 * an idr_layer from @idr->id_free.
90 *
91 * @layer_idr is to maintain backward compatibility with the old alloc
92 * interface - idr_pre_get() and idr_get_new*() - and will be removed
93 * together with per-pool preload buffer.
94 */
95static struct idr_layer *idr_layer_alloc(gfp_t gfp_mask, struct idr *layer_idr)
96{
97 struct idr_layer *new;
98
99 /* this is the old path, bypass to get_from_free_list() */
100 if (layer_idr)
101 return get_from_free_list(layer_idr);
102
Tejun Heo59bfbcf2013-03-13 14:59:49 -0700103 /*
104 * Try to allocate directly from kmem_cache. We want to try this
105 * before preload buffer; otherwise, non-preloading idr_alloc()
106 * users will end up taking advantage of preloading ones. As the
107 * following is allowed to fail for preloaded cases, suppress
108 * warning this time.
109 */
110 new = kmem_cache_zalloc(idr_layer_cache, gfp_mask | __GFP_NOWARN);
Tejun Heod5c74092013-02-27 17:03:55 -0800111 if (new)
112 return new;
113
114 /*
115 * Try to fetch one from the per-cpu preload buffer if in process
116 * context. See idr_preload() for details.
117 */
Tejun Heo59bfbcf2013-03-13 14:59:49 -0700118 if (!in_interrupt()) {
119 preempt_disable();
120 new = __this_cpu_read(idr_preload_head);
121 if (new) {
122 __this_cpu_write(idr_preload_head, new->ary[0]);
123 __this_cpu_dec(idr_preload_cnt);
124 new->ary[0] = NULL;
125 }
126 preempt_enable();
127 if (new)
128 return new;
Tejun Heod5c74092013-02-27 17:03:55 -0800129 }
Tejun Heo59bfbcf2013-03-13 14:59:49 -0700130
131 /*
132 * Both failed. Try kmem_cache again w/o adding __GFP_NOWARN so
133 * that memory allocation failure warning is printed as intended.
134 */
135 return kmem_cache_zalloc(idr_layer_cache, gfp_mask);
Tejun Heod5c74092013-02-27 17:03:55 -0800136}
137
Nadia Derbeycf481c22008-07-25 01:48:02 -0700138static void idr_layer_rcu_free(struct rcu_head *head)
139{
140 struct idr_layer *layer;
141
142 layer = container_of(head, struct idr_layer, rcu_head);
143 kmem_cache_free(idr_layer_cache, layer);
144}
145
Tejun Heo0ffc2a92013-02-27 17:05:08 -0800146static inline void free_layer(struct idr *idr, struct idr_layer *p)
Nadia Derbeycf481c22008-07-25 01:48:02 -0700147{
Lai Jiangshan15f3ec32014-06-06 14:37:14 -0700148 if (idr->hint == p)
Tejun Heo0ffc2a92013-02-27 17:05:08 -0800149 RCU_INIT_POINTER(idr->hint, NULL);
Nadia Derbeycf481c22008-07-25 01:48:02 -0700150 call_rcu(&p->rcu_head, idr_layer_rcu_free);
151}
152
Sonny Rao1eec0052006-06-25 05:49:34 -0700153/* only called when idp->lock is held */
Nadia Derbey4ae53782008-07-25 01:47:58 -0700154static void __move_to_free_list(struct idr *idp, struct idr_layer *p)
Sonny Rao1eec0052006-06-25 05:49:34 -0700155{
156 p->ary[0] = idp->id_free;
157 idp->id_free = p;
158 idp->id_free_cnt++;
159}
160
Nadia Derbey4ae53782008-07-25 01:47:58 -0700161static void move_to_free_list(struct idr *idp, struct idr_layer *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162{
Roland Dreierc259cc22006-07-14 00:24:23 -0700163 unsigned long flags;
164
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165 /*
166 * Depends on the return element being zeroed.
167 */
Roland Dreierc259cc22006-07-14 00:24:23 -0700168 spin_lock_irqsave(&idp->lock, flags);
Nadia Derbey4ae53782008-07-25 01:47:58 -0700169 __move_to_free_list(idp, p);
Roland Dreierc259cc22006-07-14 00:24:23 -0700170 spin_unlock_irqrestore(&idp->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171}
172
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900173static void idr_mark_full(struct idr_layer **pa, int id)
174{
175 struct idr_layer *p = pa[0];
176 int l = 0;
177
Tejun Heo1d9b2e12013-02-27 17:05:05 -0800178 __set_bit(id & IDR_MASK, p->bitmap);
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900179 /*
180 * If this layer is full mark the bit in the layer above to
181 * show that this part of the radix tree is full. This may
182 * complete the layer above and require walking up the radix
183 * tree.
184 */
Tejun Heo1d9b2e12013-02-27 17:05:05 -0800185 while (bitmap_full(p->bitmap, IDR_SIZE)) {
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900186 if (!(p = pa[++l]))
187 break;
188 id = id >> IDR_BITS;
Tejun Heo1d9b2e12013-02-27 17:05:05 -0800189 __set_bit((id & IDR_MASK), p->bitmap);
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900190 }
191}
192
Stephen Hemminger90ae3ae2014-04-07 15:38:52 -0700193static int __idr_pre_get(struct idr *idp, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194{
Fengguang Wu125c4c72012-10-04 17:13:15 -0700195 while (idp->id_free_cnt < MAX_IDR_FREE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196 struct idr_layer *new;
Andrew Morton5b019e92009-01-15 13:51:21 -0800197 new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800198 if (new == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199 return (0);
Nadia Derbey4ae53782008-07-25 01:47:58 -0700200 move_to_free_list(idp, new);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 }
202 return 1;
203}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204
Tejun Heo12d1b432013-02-27 17:03:53 -0800205/**
206 * sub_alloc - try to allocate an id without growing the tree depth
207 * @idp: idr handle
208 * @starting_id: id to start search at
Tejun Heo12d1b432013-02-27 17:03:53 -0800209 * @pa: idr_layer[MAX_IDR_LEVEL] used as backtrack buffer
Tejun Heod5c74092013-02-27 17:03:55 -0800210 * @gfp_mask: allocation mask for idr_layer_alloc()
211 * @layer_idr: optional idr passed to idr_layer_alloc()
Tejun Heo12d1b432013-02-27 17:03:53 -0800212 *
213 * Allocate an id in range [@starting_id, INT_MAX] from @idp without
214 * growing its depth. Returns
215 *
216 * the allocated id >= 0 if successful,
217 * -EAGAIN if the tree needs to grow for allocation to succeed,
218 * -ENOSPC if the id space is exhausted,
219 * -ENOMEM if more idr_layers need to be allocated.
220 */
Tejun Heod5c74092013-02-27 17:03:55 -0800221static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa,
222 gfp_t gfp_mask, struct idr *layer_idr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223{
224 int n, m, sh;
225 struct idr_layer *p, *new;
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900226 int l, id, oid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227
228 id = *starting_id;
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900229 restart:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230 p = idp->top;
231 l = idp->layers;
232 pa[l--] = NULL;
233 while (1) {
234 /*
235 * We run around this while until we reach the leaf node...
236 */
237 n = (id >> (IDR_BITS*l)) & IDR_MASK;
Tejun Heo1d9b2e12013-02-27 17:05:05 -0800238 m = find_next_zero_bit(p->bitmap, IDR_SIZE, n);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239 if (m == IDR_SIZE) {
240 /* no space available go back to previous layer. */
241 l++;
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900242 oid = id;
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800243 id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1;
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900244
245 /* if already at the top layer, we need to grow */
Lai Jiangshan3afb69c2014-06-06 14:37:10 -0700246 if (id > idr_max(idp->layers)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 *starting_id = id;
Tejun Heo12d1b432013-02-27 17:03:53 -0800248 return -EAGAIN;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249 }
Tejun Heod2e72762010-02-22 12:44:19 -0800250 p = pa[l];
251 BUG_ON(!p);
Tejun Heo7aae6dd2007-06-14 03:45:12 +0900252
253 /* If we need to go up one layer, continue the
254 * loop; otherwise, restart from the top.
255 */
256 sh = IDR_BITS * (l + 1);
257 if (oid >> sh == id >> sh)
258 continue;
259 else
260 goto restart;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261 }
262 if (m != n) {
263 sh = IDR_BITS*l;
264 id = ((id >> sh) ^ n ^ m) << sh;
265 }
Fengguang Wu125c4c72012-10-04 17:13:15 -0700266 if ((id >= MAX_IDR_BIT) || (id < 0))
Tejun Heo12d1b432013-02-27 17:03:53 -0800267 return -ENOSPC;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700268 if (l == 0)
269 break;
270 /*
271 * Create the layer below if it is missing.
272 */
273 if (!p->ary[m]) {
Tejun Heod5c74092013-02-27 17:03:55 -0800274 new = idr_layer_alloc(gfp_mask, layer_idr);
Nadia Derbey4ae53782008-07-25 01:47:58 -0700275 if (!new)
Tejun Heo12d1b432013-02-27 17:03:53 -0800276 return -ENOMEM;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800277 new->layer = l-1;
Tejun Heo54616282013-02-27 17:05:07 -0800278 new->prefix = id & idr_layer_prefix_mask(new->layer);
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700279 rcu_assign_pointer(p->ary[m], new);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280 p->count++;
281 }
282 pa[l--] = p;
283 p = p->ary[m];
284 }
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900285
286 pa[l] = p;
287 return id;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288}
289
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900290static int idr_get_empty_slot(struct idr *idp, int starting_id,
Tejun Heod5c74092013-02-27 17:03:55 -0800291 struct idr_layer **pa, gfp_t gfp_mask,
292 struct idr *layer_idr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293{
294 struct idr_layer *p, *new;
295 int layers, v, id;
Roland Dreierc259cc22006-07-14 00:24:23 -0700296 unsigned long flags;
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800297
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298 id = starting_id;
299build_up:
300 p = idp->top;
301 layers = idp->layers;
302 if (unlikely(!p)) {
Tejun Heod5c74092013-02-27 17:03:55 -0800303 if (!(p = idr_layer_alloc(gfp_mask, layer_idr)))
Tejun Heo12d1b432013-02-27 17:03:53 -0800304 return -ENOMEM;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800305 p->layer = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306 layers = 1;
307 }
308 /*
309 * Add a new layer to the top of the tree if the requested
310 * id is larger than the currently allocated space.
311 */
Tejun Heo326cf0f2013-02-27 17:05:02 -0800312 while (id > idr_max(layers)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313 layers++;
Manfred Spraul711a49a2008-12-10 18:17:06 +0100314 if (!p->count) {
315 /* special case: if the tree is currently empty,
316 * then we grow the tree by moving the top node
317 * upwards.
318 */
319 p->layer++;
Tejun Heo54616282013-02-27 17:05:07 -0800320 WARN_ON_ONCE(p->prefix);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321 continue;
Manfred Spraul711a49a2008-12-10 18:17:06 +0100322 }
Tejun Heod5c74092013-02-27 17:03:55 -0800323 if (!(new = idr_layer_alloc(gfp_mask, layer_idr))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324 /*
325 * The allocation failed. If we built part of
326 * the structure tear it down.
327 */
Roland Dreierc259cc22006-07-14 00:24:23 -0700328 spin_lock_irqsave(&idp->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 for (new = p; p && p != idp->top; new = p) {
330 p = p->ary[0];
331 new->ary[0] = NULL;
Tejun Heo1d9b2e12013-02-27 17:05:05 -0800332 new->count = 0;
333 bitmap_clear(new->bitmap, 0, IDR_SIZE);
Nadia Derbey4ae53782008-07-25 01:47:58 -0700334 __move_to_free_list(idp, new);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 }
Roland Dreierc259cc22006-07-14 00:24:23 -0700336 spin_unlock_irqrestore(&idp->lock, flags);
Tejun Heo12d1b432013-02-27 17:03:53 -0800337 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338 }
339 new->ary[0] = p;
340 new->count = 1;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800341 new->layer = layers-1;
Tejun Heo54616282013-02-27 17:05:07 -0800342 new->prefix = id & idr_layer_prefix_mask(new->layer);
Tejun Heo1d9b2e12013-02-27 17:05:05 -0800343 if (bitmap_full(p->bitmap, IDR_SIZE))
344 __set_bit(0, new->bitmap);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345 p = new;
346 }
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700347 rcu_assign_pointer(idp->top, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348 idp->layers = layers;
Tejun Heod5c74092013-02-27 17:03:55 -0800349 v = sub_alloc(idp, &id, pa, gfp_mask, layer_idr);
Tejun Heo12d1b432013-02-27 17:03:53 -0800350 if (v == -EAGAIN)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 goto build_up;
352 return(v);
353}
354
Tejun Heo3594eb22013-02-27 17:03:54 -0800355/*
356 * @id and @pa are from a successful allocation from idr_get_empty_slot().
357 * Install the user pointer @ptr and mark the slot full.
358 */
Tejun Heo0ffc2a92013-02-27 17:05:08 -0800359static void idr_fill_slot(struct idr *idr, void *ptr, int id,
360 struct idr_layer **pa)
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900361{
Tejun Heo0ffc2a92013-02-27 17:05:08 -0800362 /* update hint used for lookup, cleared from free_layer() */
363 rcu_assign_pointer(idr->hint, pa[0]);
364
Tejun Heo3594eb22013-02-27 17:03:54 -0800365 rcu_assign_pointer(pa[0]->ary[id & IDR_MASK], (struct idr_layer *)ptr);
366 pa[0]->count++;
367 idr_mark_full(pa, id);
Tejun Heoe33ac8b2007-06-14 03:45:12 +0900368}
369
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370
Tejun Heod5c74092013-02-27 17:03:55 -0800371/**
372 * idr_preload - preload for idr_alloc()
373 * @gfp_mask: allocation mask to use for preloading
374 *
375 * Preload per-cpu layer buffer for idr_alloc(). Can only be used from
376 * process context and each idr_preload() invocation should be matched with
377 * idr_preload_end(). Note that preemption is disabled while preloaded.
378 *
379 * The first idr_alloc() in the preloaded section can be treated as if it
380 * were invoked with @gfp_mask used for preloading. This allows using more
381 * permissive allocation masks for idrs protected by spinlocks.
382 *
383 * For example, if idr_alloc() below fails, the failure can be treated as
384 * if idr_alloc() were called with GFP_KERNEL rather than GFP_NOWAIT.
385 *
386 * idr_preload(GFP_KERNEL);
387 * spin_lock(lock);
388 *
389 * id = idr_alloc(idr, ptr, start, end, GFP_NOWAIT);
390 *
391 * spin_unlock(lock);
392 * idr_preload_end();
393 * if (id < 0)
394 * error;
395 */
396void idr_preload(gfp_t gfp_mask)
397{
398 /*
399 * Consuming preload buffer from non-process context breaks preload
400 * allocation guarantee. Disallow usage from those contexts.
401 */
402 WARN_ON_ONCE(in_interrupt());
403 might_sleep_if(gfp_mask & __GFP_WAIT);
404
405 preempt_disable();
406
407 /*
408 * idr_alloc() is likely to succeed w/o full idr_layer buffer and
409 * return value from idr_alloc() needs to be checked for failure
410 * anyway. Silently give up if allocation fails. The caller can
411 * treat failures from idr_alloc() as if idr_alloc() were called
412 * with @gfp_mask which should be enough.
413 */
414 while (__this_cpu_read(idr_preload_cnt) < MAX_IDR_FREE) {
415 struct idr_layer *new;
416
417 preempt_enable();
418 new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
419 preempt_disable();
420 if (!new)
421 break;
422
423 /* link the new one to per-cpu preload list */
424 new->ary[0] = __this_cpu_read(idr_preload_head);
425 __this_cpu_write(idr_preload_head, new);
426 __this_cpu_inc(idr_preload_cnt);
427 }
428}
429EXPORT_SYMBOL(idr_preload);
430
431/**
432 * idr_alloc - allocate new idr entry
433 * @idr: the (initialized) idr
434 * @ptr: pointer to be associated with the new id
435 * @start: the minimum id (inclusive)
436 * @end: the maximum id (exclusive, <= 0 for max)
437 * @gfp_mask: memory allocation flags
438 *
439 * Allocate an id in [start, end) and associate it with @ptr. If no ID is
440 * available in the specified range, returns -ENOSPC. On memory allocation
441 * failure, returns -ENOMEM.
442 *
443 * Note that @end is treated as max when <= 0. This is to always allow
444 * using @start + N as @end as long as N is inside integer range.
445 *
446 * The user is responsible for exclusively synchronizing all operations
447 * which may modify @idr. However, read-only accesses such as idr_find()
448 * or iteration can be performed under RCU read lock provided the user
449 * destroys @ptr in RCU-safe way after removal from idr.
450 */
451int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask)
452{
453 int max = end > 0 ? end - 1 : INT_MAX; /* inclusive upper limit */
Tejun Heo326cf0f2013-02-27 17:05:02 -0800454 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
Tejun Heod5c74092013-02-27 17:03:55 -0800455 int id;
456
457 might_sleep_if(gfp_mask & __GFP_WAIT);
458
459 /* sanity checks */
460 if (WARN_ON_ONCE(start < 0))
461 return -EINVAL;
462 if (unlikely(max < start))
463 return -ENOSPC;
464
465 /* allocate id */
466 id = idr_get_empty_slot(idr, start, pa, gfp_mask, NULL);
467 if (unlikely(id < 0))
468 return id;
469 if (unlikely(id > max))
470 return -ENOSPC;
471
Tejun Heo0ffc2a92013-02-27 17:05:08 -0800472 idr_fill_slot(idr, ptr, id, pa);
Tejun Heod5c74092013-02-27 17:03:55 -0800473 return id;
474}
475EXPORT_SYMBOL_GPL(idr_alloc);
476
Jeff Layton3e6628c42013-04-29 16:21:16 -0700477/**
478 * idr_alloc_cyclic - allocate new idr entry in a cyclical fashion
479 * @idr: the (initialized) idr
480 * @ptr: pointer to be associated with the new id
481 * @start: the minimum id (inclusive)
482 * @end: the maximum id (exclusive, <= 0 for max)
483 * @gfp_mask: memory allocation flags
484 *
485 * Essentially the same as idr_alloc, but prefers to allocate progressively
486 * higher ids if it can. If the "cur" counter wraps, then it will start again
487 * at the "start" end of the range and allocate one that has already been used.
488 */
489int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end,
490 gfp_t gfp_mask)
491{
492 int id;
493
494 id = idr_alloc(idr, ptr, max(start, idr->cur), end, gfp_mask);
495 if (id == -ENOSPC)
496 id = idr_alloc(idr, ptr, start, end, gfp_mask);
497
498 if (likely(id >= 0))
499 idr->cur = id + 1;
500 return id;
501}
502EXPORT_SYMBOL(idr_alloc_cyclic);
503
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504static void idr_remove_warning(int id)
505{
Jean Delvaredd04b452013-07-03 15:08:47 -0700506 WARN(1, "idr_remove called for id=%d which is not allocated.\n", id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507}
508
509static void sub_remove(struct idr *idp, int shift, int id)
510{
511 struct idr_layer *p = idp->top;
Tejun Heo326cf0f2013-02-27 17:05:02 -0800512 struct idr_layer **pa[MAX_IDR_LEVEL + 1];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513 struct idr_layer ***paa = &pa[0];
Nadia Derbeycf481c22008-07-25 01:48:02 -0700514 struct idr_layer *to_free;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515 int n;
516
517 *paa = NULL;
518 *++paa = &idp->top;
519
520 while ((shift > 0) && p) {
521 n = (id >> shift) & IDR_MASK;
Tejun Heo1d9b2e12013-02-27 17:05:05 -0800522 __clear_bit(n, p->bitmap);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523 *++paa = &p->ary[n];
524 p = p->ary[n];
525 shift -= IDR_BITS;
526 }
527 n = id & IDR_MASK;
Tejun Heo1d9b2e12013-02-27 17:05:05 -0800528 if (likely(p != NULL && test_bit(n, p->bitmap))) {
529 __clear_bit(n, p->bitmap);
Monam Agarwal3f59b062014-04-07 15:38:54 -0700530 RCU_INIT_POINTER(p->ary[n], NULL);
Nadia Derbeycf481c22008-07-25 01:48:02 -0700531 to_free = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532 while(*paa && ! --((**paa)->count)){
Nadia Derbeycf481c22008-07-25 01:48:02 -0700533 if (to_free)
Tejun Heo0ffc2a92013-02-27 17:05:08 -0800534 free_layer(idp, to_free);
Nadia Derbeycf481c22008-07-25 01:48:02 -0700535 to_free = **paa;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536 **paa-- = NULL;
537 }
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800538 if (!*paa)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539 idp->layers = 0;
Nadia Derbeycf481c22008-07-25 01:48:02 -0700540 if (to_free)
Tejun Heo0ffc2a92013-02-27 17:05:08 -0800541 free_layer(idp, to_free);
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800542 } else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543 idr_remove_warning(id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544}
545
546/**
Randy Dunlap56083ab2010-10-26 14:19:08 -0700547 * idr_remove - remove the given id and free its slot
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800548 * @idp: idr handle
549 * @id: unique key
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550 */
551void idr_remove(struct idr *idp, int id)
552{
553 struct idr_layer *p;
Nadia Derbeycf481c22008-07-25 01:48:02 -0700554 struct idr_layer *to_free;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700555
Tejun Heo2e1c9b22013-03-08 12:43:30 -0800556 if (id < 0)
Tejun Heoe8c8d1b2013-02-27 17:05:04 -0800557 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558
Lai Jiangshan8f9f6652014-06-06 14:37:11 -0700559 if (id > idr_max(idp->layers)) {
560 idr_remove_warning(id);
561 return;
562 }
563
Linus Torvalds1da177e2005-04-16 15:20:36 -0700564 sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
Jesper Juhle15ae2d2005-10-30 15:02:14 -0800565 if (idp->top && idp->top->count == 1 && (idp->layers > 1) &&
Nadia Derbeycf481c22008-07-25 01:48:02 -0700566 idp->top->ary[0]) {
567 /*
568 * Single child at leftmost slot: we can shrink the tree.
569 * This level is not needed anymore since when layers are
570 * inserted, they are inserted at the top of the existing
571 * tree.
572 */
573 to_free = idp->top;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574 p = idp->top->ary[0];
Nadia Derbeycf481c22008-07-25 01:48:02 -0700575 rcu_assign_pointer(idp->top, p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576 --idp->layers;
Tejun Heo1d9b2e12013-02-27 17:05:05 -0800577 to_free->count = 0;
578 bitmap_clear(to_free->bitmap, 0, IDR_SIZE);
Tejun Heo0ffc2a92013-02-27 17:05:08 -0800579 free_layer(idp, to_free);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700580 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581}
582EXPORT_SYMBOL(idr_remove);
583
Stephen Hemminger90ae3ae2014-04-07 15:38:52 -0700584static void __idr_remove_all(struct idr *idp)
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700585{
Oleg Nesterov6ace06dc2007-07-31 00:39:19 -0700586 int n, id, max;
Imre Deak2dcb22b2010-05-26 14:43:38 -0700587 int bt_mask;
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700588 struct idr_layer *p;
Tejun Heo326cf0f2013-02-27 17:05:02 -0800589 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700590 struct idr_layer **paa = &pa[0];
591
592 n = idp->layers * IDR_BITS;
593 p = idp->top;
Monam Agarwal3f59b062014-04-07 15:38:54 -0700594 RCU_INIT_POINTER(idp->top, NULL);
Tejun Heo326cf0f2013-02-27 17:05:02 -0800595 max = idr_max(idp->layers);
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700596
597 id = 0;
Tejun Heo326cf0f2013-02-27 17:05:02 -0800598 while (id >= 0 && id <= max) {
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700599 while (n > IDR_BITS && p) {
600 n -= IDR_BITS;
601 *paa++ = p;
602 p = p->ary[(id >> n) & IDR_MASK];
603 }
604
Imre Deak2dcb22b2010-05-26 14:43:38 -0700605 bt_mask = id;
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700606 id += 1 << n;
Imre Deak2dcb22b2010-05-26 14:43:38 -0700607 /* Get the highest bit that the above add changed from 0->1. */
608 while (n < fls(id ^ bt_mask)) {
Nadia Derbeycf481c22008-07-25 01:48:02 -0700609 if (p)
Tejun Heo0ffc2a92013-02-27 17:05:08 -0800610 free_layer(idp, p);
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700611 n += IDR_BITS;
612 p = *--paa;
613 }
614 }
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700615 idp->layers = 0;
616}
Kristian Hoegsberg23936cc2007-07-15 23:37:24 -0700617
618/**
Andrew Morton8d3b3592005-10-23 12:57:18 -0700619 * idr_destroy - release all cached layers within an idr tree
Naohiro Aotaea24ea82010-08-31 00:37:03 +0900620 * @idp: idr handle
Tejun Heo9bb26bc2013-02-27 17:03:35 -0800621 *
622 * Free all id mappings and all idp_layers. After this function, @idp is
623 * completely unused and can be freed / recycled. The caller is
624 * responsible for ensuring that no one else accesses @idp during or after
625 * idr_destroy().
626 *
627 * A typical clean-up sequence for objects stored in an idr tree will use
628 * idr_for_each() to free all objects, if necessay, then idr_destroy() to
629 * free up the id mappings and cached idr_layers.
Andrew Morton8d3b3592005-10-23 12:57:18 -0700630 */
631void idr_destroy(struct idr *idp)
632{
Tejun Heofe6e24e2013-02-27 17:03:50 -0800633 __idr_remove_all(idp);
Tejun Heo9bb26bc2013-02-27 17:03:35 -0800634
Andrew Morton8d3b3592005-10-23 12:57:18 -0700635 while (idp->id_free_cnt) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700636 struct idr_layer *p = get_from_free_list(idp);
Andrew Morton8d3b3592005-10-23 12:57:18 -0700637 kmem_cache_free(idr_layer_cache, p);
638 }
639}
640EXPORT_SYMBOL(idr_destroy);
641
Tejun Heo0ffc2a92013-02-27 17:05:08 -0800642void *idr_find_slowpath(struct idr *idp, int id)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700643{
644 int n;
645 struct idr_layer *p;
646
Tejun Heo2e1c9b22013-03-08 12:43:30 -0800647 if (id < 0)
Tejun Heoe8c8d1b2013-02-27 17:05:04 -0800648 return NULL;
649
Paul E. McKenney96be7532010-02-22 17:04:55 -0800650 p = rcu_dereference_raw(idp->top);
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800651 if (!p)
652 return NULL;
653 n = (p->layer+1) * IDR_BITS;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700654
Tejun Heo326cf0f2013-02-27 17:05:02 -0800655 if (id > idr_max(p->layer + 1))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656 return NULL;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800657 BUG_ON(n == 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700658
659 while (n > 0 && p) {
660 n -= IDR_BITS;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800661 BUG_ON(n != p->layer*IDR_BITS);
Paul E. McKenney96be7532010-02-22 17:04:55 -0800662 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700663 }
664 return((void *)p);
665}
Tejun Heo0ffc2a92013-02-27 17:05:08 -0800666EXPORT_SYMBOL(idr_find_slowpath);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700667
Jeff Mahoney5806f072006-06-26 00:27:19 -0700668/**
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700669 * idr_for_each - iterate through all stored pointers
670 * @idp: idr handle
671 * @fn: function to be called for each pointer
672 * @data: data passed back to callback function
673 *
674 * Iterate over the pointers registered with the given idr. The
675 * callback function will be called for each pointer currently
676 * registered, passing the id, the pointer and the data pointer passed
677 * to this function. It is not safe to modify the idr tree while in
678 * the callback, so functions such as idr_get_new and idr_remove are
679 * not allowed.
680 *
681 * We check the return of @fn each time. If it returns anything other
Randy Dunlap56083ab2010-10-26 14:19:08 -0700682 * than %0, we break out and return that value.
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700683 *
684 * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove().
685 */
686int idr_for_each(struct idr *idp,
687 int (*fn)(int id, void *p, void *data), void *data)
688{
689 int n, id, max, error = 0;
690 struct idr_layer *p;
Tejun Heo326cf0f2013-02-27 17:05:02 -0800691 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700692 struct idr_layer **paa = &pa[0];
693
694 n = idp->layers * IDR_BITS;
Paul E. McKenney96be7532010-02-22 17:04:55 -0800695 p = rcu_dereference_raw(idp->top);
Tejun Heo326cf0f2013-02-27 17:05:02 -0800696 max = idr_max(idp->layers);
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700697
698 id = 0;
Tejun Heo326cf0f2013-02-27 17:05:02 -0800699 while (id >= 0 && id <= max) {
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700700 while (n > 0 && p) {
701 n -= IDR_BITS;
702 *paa++ = p;
Paul E. McKenney96be7532010-02-22 17:04:55 -0800703 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
Kristian Hoegsberg96d7fa42007-07-15 23:37:24 -0700704 }
705
706 if (p) {
707 error = fn(id, (void *)p, data);
708 if (error)
709 break;
710 }
711
712 id += 1 << n;
713 while (n < fls(id)) {
714 n += IDR_BITS;
715 p = *--paa;
716 }
717 }
718
719 return error;
720}
721EXPORT_SYMBOL(idr_for_each);
722
723/**
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700724 * idr_get_next - lookup next object of id to given id.
725 * @idp: idr handle
Naohiro Aotaea24ea82010-08-31 00:37:03 +0900726 * @nextidp: pointer to lookup key
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700727 *
728 * Returns pointer to registered object with id, which is next number to
Naohiro Aota1458ce12010-08-27 17:43:46 +0900729 * given id. After being looked up, *@nextidp will be updated for the next
730 * iteration.
Hugh Dickins9f7de822012-03-21 16:34:20 -0700731 *
732 * This function can be called under rcu_read_lock(), given that the leaf
733 * pointers lifetimes are correctly managed.
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700734 */
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700735void *idr_get_next(struct idr *idp, int *nextidp)
736{
Tejun Heo326cf0f2013-02-27 17:05:02 -0800737 struct idr_layer *p, *pa[MAX_IDR_LEVEL + 1];
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700738 struct idr_layer **paa = &pa[0];
739 int id = *nextidp;
740 int n, max;
741
742 /* find first ent */
Paul E. McKenney94bfa3b2010-06-07 17:09:45 -0700743 p = rcu_dereference_raw(idp->top);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700744 if (!p)
745 return NULL;
Hugh Dickins9f7de822012-03-21 16:34:20 -0700746 n = (p->layer + 1) * IDR_BITS;
Tejun Heo326cf0f2013-02-27 17:05:02 -0800747 max = idr_max(p->layer + 1);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700748
Tejun Heo326cf0f2013-02-27 17:05:02 -0800749 while (id >= 0 && id <= max) {
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700750 while (n > 0 && p) {
751 n -= IDR_BITS;
752 *paa++ = p;
Paul E. McKenney94bfa3b2010-06-07 17:09:45 -0700753 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700754 }
755
756 if (p) {
757 *nextidp = id;
758 return p;
759 }
760
Tejun Heo6cdae742013-02-27 17:03:34 -0800761 /*
762 * Proceed to the next layer at the current level. Unlike
763 * idr_for_each(), @id isn't guaranteed to be aligned to
764 * layer boundary at this point and adding 1 << n may
765 * incorrectly skip IDs. Make sure we jump to the
766 * beginning of the next layer using round_up().
767 */
768 id = round_up(id + 1, 1 << n);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700769 while (n < fls(id)) {
770 n += IDR_BITS;
771 p = *--paa;
772 }
773 }
774 return NULL;
775}
Ben Hutchings4d1ee802010-01-29 20:59:17 +0000776EXPORT_SYMBOL(idr_get_next);
KAMEZAWA Hiroyuki38460b42009-04-02 16:57:25 -0700777
778
779/**
Jeff Mahoney5806f072006-06-26 00:27:19 -0700780 * idr_replace - replace pointer for given id
781 * @idp: idr handle
782 * @ptr: pointer you want associated with the id
783 * @id: lookup key
784 *
785 * Replace the pointer registered with an id and return the old value.
Randy Dunlap56083ab2010-10-26 14:19:08 -0700786 * A %-ENOENT return indicates that @id was not found.
787 * A %-EINVAL return indicates that @id was not within valid constraints.
Jeff Mahoney5806f072006-06-26 00:27:19 -0700788 *
Nadia Derbeycf481c22008-07-25 01:48:02 -0700789 * The caller must serialize with writers.
Jeff Mahoney5806f072006-06-26 00:27:19 -0700790 */
791void *idr_replace(struct idr *idp, void *ptr, int id)
792{
793 int n;
794 struct idr_layer *p, *old_p;
795
Tejun Heo2e1c9b22013-03-08 12:43:30 -0800796 if (id < 0)
Tejun Heoe8c8d1b2013-02-27 17:05:04 -0800797 return ERR_PTR(-EINVAL);
798
Jeff Mahoney5806f072006-06-26 00:27:19 -0700799 p = idp->top;
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800800 if (!p)
Lai Jiangshanb93804b2014-06-06 14:37:13 -0700801 return ERR_PTR(-ENOENT);
Manfred Spraul6ff2d392008-12-01 13:14:02 -0800802
Lai Jiangshan3afb69c2014-06-06 14:37:10 -0700803 if (id > idr_max(p->layer + 1))
Lai Jiangshanb93804b2014-06-06 14:37:13 -0700804 return ERR_PTR(-ENOENT);
Jeff Mahoney5806f072006-06-26 00:27:19 -0700805
Lai Jiangshan3afb69c2014-06-06 14:37:10 -0700806 n = p->layer * IDR_BITS;
Jeff Mahoney5806f072006-06-26 00:27:19 -0700807 while ((n > 0) && p) {
808 p = p->ary[(id >> n) & IDR_MASK];
809 n -= IDR_BITS;
810 }
811
812 n = id & IDR_MASK;
Tejun Heo1d9b2e12013-02-27 17:05:05 -0800813 if (unlikely(p == NULL || !test_bit(n, p->bitmap)))
Jeff Mahoney5806f072006-06-26 00:27:19 -0700814 return ERR_PTR(-ENOENT);
815
816 old_p = p->ary[n];
Nadia Derbeycf481c22008-07-25 01:48:02 -0700817 rcu_assign_pointer(p->ary[n], ptr);
Jeff Mahoney5806f072006-06-26 00:27:19 -0700818
819 return old_p;
820}
821EXPORT_SYMBOL(idr_replace);
822
Akinobu Mita199f0ca2008-04-29 01:03:13 -0700823void __init idr_init_cache(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824{
Akinobu Mita199f0ca2008-04-29 01:03:13 -0700825 idr_layer_cache = kmem_cache_create("idr_layer_cache",
Andrew Morton5b019e92009-01-15 13:51:21 -0800826 sizeof(struct idr_layer), 0, SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700827}
828
829/**
830 * idr_init - initialize idr handle
831 * @idp: idr handle
832 *
833 * This function is use to set up the handle (@idp) that you will pass
834 * to the rest of the functions.
835 */
836void idr_init(struct idr *idp)
837{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700838 memset(idp, 0, sizeof(struct idr));
839 spin_lock_init(&idp->lock);
840}
841EXPORT_SYMBOL(idr_init);
Tejun Heo72dba582007-06-14 03:45:13 +0900842
Andreas Gruenbacher05f7a7d2011-08-08 23:36:56 +0200843static int idr_has_entry(int id, void *p, void *data)
844{
845 return 1;
846}
847
848bool idr_is_empty(struct idr *idp)
849{
850 return !idr_for_each(idp, idr_has_entry, NULL);
851}
852EXPORT_SYMBOL(idr_is_empty);
Tejun Heo72dba582007-06-14 03:45:13 +0900853
Randy Dunlap56083ab2010-10-26 14:19:08 -0700854/**
855 * DOC: IDA description
Tejun Heo72dba582007-06-14 03:45:13 +0900856 * IDA - IDR based ID allocator
857 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700858 * This is id allocator without id -> pointer translation. Memory
Tejun Heo72dba582007-06-14 03:45:13 +0900859 * usage is much lower than full blown idr because each id only
860 * occupies a bit. ida uses a custom leaf node which contains
861 * IDA_BITMAP_BITS slots.
862 *
863 * 2007-04-25 written by Tejun Heo <htejun@gmail.com>
864 */
865
866static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap)
867{
868 unsigned long flags;
869
870 if (!ida->free_bitmap) {
871 spin_lock_irqsave(&ida->idr.lock, flags);
872 if (!ida->free_bitmap) {
873 ida->free_bitmap = bitmap;
874 bitmap = NULL;
875 }
876 spin_unlock_irqrestore(&ida->idr.lock, flags);
877 }
878
879 kfree(bitmap);
880}
881
882/**
883 * ida_pre_get - reserve resources for ida allocation
884 * @ida: ida handle
885 * @gfp_mask: memory allocation flag
886 *
887 * This function should be called prior to locking and calling the
888 * following function. It preallocates enough memory to satisfy the
889 * worst possible allocation.
890 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700891 * If the system is REALLY out of memory this function returns %0,
892 * otherwise %1.
Tejun Heo72dba582007-06-14 03:45:13 +0900893 */
894int ida_pre_get(struct ida *ida, gfp_t gfp_mask)
895{
896 /* allocate idr_layers */
Tejun Heoc8615d32013-03-13 14:59:42 -0700897 if (!__idr_pre_get(&ida->idr, gfp_mask))
Tejun Heo72dba582007-06-14 03:45:13 +0900898 return 0;
899
900 /* allocate free_bitmap */
901 if (!ida->free_bitmap) {
902 struct ida_bitmap *bitmap;
903
904 bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask);
905 if (!bitmap)
906 return 0;
907
908 free_bitmap(ida, bitmap);
909 }
910
911 return 1;
912}
913EXPORT_SYMBOL(ida_pre_get);
914
915/**
916 * ida_get_new_above - allocate new ID above or equal to a start id
917 * @ida: ida handle
Naohiro Aotaea24ea82010-08-31 00:37:03 +0900918 * @starting_id: id to start search at
Tejun Heo72dba582007-06-14 03:45:13 +0900919 * @p_id: pointer to the allocated handle
920 *
Wang Sheng-Huie3816c52011-10-31 17:12:36 -0700921 * Allocate new ID above or equal to @starting_id. It should be called
922 * with any required locks.
Tejun Heo72dba582007-06-14 03:45:13 +0900923 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700924 * If memory is required, it will return %-EAGAIN, you should unlock
Tejun Heo72dba582007-06-14 03:45:13 +0900925 * and go back to the ida_pre_get() call. If the ida is full, it will
Randy Dunlap56083ab2010-10-26 14:19:08 -0700926 * return %-ENOSPC.
Tejun Heo72dba582007-06-14 03:45:13 +0900927 *
Randy Dunlap56083ab2010-10-26 14:19:08 -0700928 * @p_id returns a value in the range @starting_id ... %0x7fffffff.
Tejun Heo72dba582007-06-14 03:45:13 +0900929 */
930int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
931{
Tejun Heo326cf0f2013-02-27 17:05:02 -0800932 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
Tejun Heo72dba582007-06-14 03:45:13 +0900933 struct ida_bitmap *bitmap;
934 unsigned long flags;
935 int idr_id = starting_id / IDA_BITMAP_BITS;
936 int offset = starting_id % IDA_BITMAP_BITS;
937 int t, id;
938
939 restart:
940 /* get vacant slot */
Tejun Heod5c74092013-02-27 17:03:55 -0800941 t = idr_get_empty_slot(&ida->idr, idr_id, pa, 0, &ida->idr);
Nadia Derbey944ca052008-07-25 01:47:59 -0700942 if (t < 0)
Tejun Heo12d1b432013-02-27 17:03:53 -0800943 return t == -ENOMEM ? -EAGAIN : t;
Tejun Heo72dba582007-06-14 03:45:13 +0900944
Fengguang Wu125c4c72012-10-04 17:13:15 -0700945 if (t * IDA_BITMAP_BITS >= MAX_IDR_BIT)
Tejun Heo72dba582007-06-14 03:45:13 +0900946 return -ENOSPC;
947
948 if (t != idr_id)
949 offset = 0;
950 idr_id = t;
951
952 /* if bitmap isn't there, create a new one */
953 bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK];
954 if (!bitmap) {
955 spin_lock_irqsave(&ida->idr.lock, flags);
956 bitmap = ida->free_bitmap;
957 ida->free_bitmap = NULL;
958 spin_unlock_irqrestore(&ida->idr.lock, flags);
959
960 if (!bitmap)
961 return -EAGAIN;
962
963 memset(bitmap, 0, sizeof(struct ida_bitmap));
Nadia Derbey3219b3b2008-07-25 01:48:00 -0700964 rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK],
965 (void *)bitmap);
Tejun Heo72dba582007-06-14 03:45:13 +0900966 pa[0]->count++;
967 }
968
969 /* lookup for empty slot */
970 t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset);
971 if (t == IDA_BITMAP_BITS) {
972 /* no empty slot after offset, continue to the next chunk */
973 idr_id++;
974 offset = 0;
975 goto restart;
976 }
977
978 id = idr_id * IDA_BITMAP_BITS + t;
Fengguang Wu125c4c72012-10-04 17:13:15 -0700979 if (id >= MAX_IDR_BIT)
Tejun Heo72dba582007-06-14 03:45:13 +0900980 return -ENOSPC;
981
982 __set_bit(t, bitmap->bitmap);
983 if (++bitmap->nr_busy == IDA_BITMAP_BITS)
984 idr_mark_full(pa, idr_id);
985
986 *p_id = id;
987
988 /* Each leaf node can handle nearly a thousand slots and the
989 * whole idea of ida is to have small memory foot print.
990 * Throw away extra resources one by one after each successful
991 * allocation.
992 */
993 if (ida->idr.id_free_cnt || ida->free_bitmap) {
Nadia Derbey4ae53782008-07-25 01:47:58 -0700994 struct idr_layer *p = get_from_free_list(&ida->idr);
Tejun Heo72dba582007-06-14 03:45:13 +0900995 if (p)
996 kmem_cache_free(idr_layer_cache, p);
997 }
998
999 return 0;
1000}
1001EXPORT_SYMBOL(ida_get_new_above);
1002
1003/**
Tejun Heo72dba582007-06-14 03:45:13 +09001004 * ida_remove - remove the given ID
1005 * @ida: ida handle
1006 * @id: ID to free
1007 */
1008void ida_remove(struct ida *ida, int id)
1009{
1010 struct idr_layer *p = ida->idr.top;
1011 int shift = (ida->idr.layers - 1) * IDR_BITS;
1012 int idr_id = id / IDA_BITMAP_BITS;
1013 int offset = id % IDA_BITMAP_BITS;
1014 int n;
1015 struct ida_bitmap *bitmap;
1016
Lai Jiangshan8f9f6652014-06-06 14:37:11 -07001017 if (idr_id > idr_max(ida->idr.layers))
1018 goto err;
1019
Tejun Heo72dba582007-06-14 03:45:13 +09001020 /* clear full bits while looking up the leaf idr_layer */
1021 while ((shift > 0) && p) {
1022 n = (idr_id >> shift) & IDR_MASK;
Tejun Heo1d9b2e12013-02-27 17:05:05 -08001023 __clear_bit(n, p->bitmap);
Tejun Heo72dba582007-06-14 03:45:13 +09001024 p = p->ary[n];
1025 shift -= IDR_BITS;
1026 }
1027
1028 if (p == NULL)
1029 goto err;
1030
1031 n = idr_id & IDR_MASK;
Tejun Heo1d9b2e12013-02-27 17:05:05 -08001032 __clear_bit(n, p->bitmap);
Tejun Heo72dba582007-06-14 03:45:13 +09001033
1034 bitmap = (void *)p->ary[n];
Lai Jiangshanaef0f622014-06-06 14:37:12 -07001035 if (!bitmap || !test_bit(offset, bitmap->bitmap))
Tejun Heo72dba582007-06-14 03:45:13 +09001036 goto err;
1037
1038 /* update bitmap and remove it if empty */
1039 __clear_bit(offset, bitmap->bitmap);
1040 if (--bitmap->nr_busy == 0) {
Tejun Heo1d9b2e12013-02-27 17:05:05 -08001041 __set_bit(n, p->bitmap); /* to please idr_remove() */
Tejun Heo72dba582007-06-14 03:45:13 +09001042 idr_remove(&ida->idr, idr_id);
1043 free_bitmap(ida, bitmap);
1044 }
1045
1046 return;
1047
1048 err:
Jean Delvaredd04b452013-07-03 15:08:47 -07001049 WARN(1, "ida_remove called for id=%d which is not allocated.\n", id);
Tejun Heo72dba582007-06-14 03:45:13 +09001050}
1051EXPORT_SYMBOL(ida_remove);
1052
1053/**
1054 * ida_destroy - release all cached layers within an ida tree
Naohiro Aotaea24ea82010-08-31 00:37:03 +09001055 * @ida: ida handle
Tejun Heo72dba582007-06-14 03:45:13 +09001056 */
1057void ida_destroy(struct ida *ida)
1058{
1059 idr_destroy(&ida->idr);
1060 kfree(ida->free_bitmap);
1061}
1062EXPORT_SYMBOL(ida_destroy);
1063
1064/**
Rusty Russell88eca022011-08-03 16:21:06 -07001065 * ida_simple_get - get a new id.
1066 * @ida: the (initialized) ida.
1067 * @start: the minimum id (inclusive, < 0x8000000)
1068 * @end: the maximum id (exclusive, < 0x8000000 or 0)
1069 * @gfp_mask: memory allocation flags
1070 *
1071 * Allocates an id in the range start <= id < end, or returns -ENOSPC.
1072 * On memory allocation failure, returns -ENOMEM.
1073 *
1074 * Use ida_simple_remove() to get rid of an id.
1075 */
1076int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
1077 gfp_t gfp_mask)
1078{
1079 int ret, id;
1080 unsigned int max;
Tejun Heo46cbc1d2011-11-02 13:38:46 -07001081 unsigned long flags;
Rusty Russell88eca022011-08-03 16:21:06 -07001082
1083 BUG_ON((int)start < 0);
1084 BUG_ON((int)end < 0);
1085
1086 if (end == 0)
1087 max = 0x80000000;
1088 else {
1089 BUG_ON(end < start);
1090 max = end - 1;
1091 }
1092
1093again:
1094 if (!ida_pre_get(ida, gfp_mask))
1095 return -ENOMEM;
1096
Tejun Heo46cbc1d2011-11-02 13:38:46 -07001097 spin_lock_irqsave(&simple_ida_lock, flags);
Rusty Russell88eca022011-08-03 16:21:06 -07001098 ret = ida_get_new_above(ida, start, &id);
1099 if (!ret) {
1100 if (id > max) {
1101 ida_remove(ida, id);
1102 ret = -ENOSPC;
1103 } else {
1104 ret = id;
1105 }
1106 }
Tejun Heo46cbc1d2011-11-02 13:38:46 -07001107 spin_unlock_irqrestore(&simple_ida_lock, flags);
Rusty Russell88eca022011-08-03 16:21:06 -07001108
1109 if (unlikely(ret == -EAGAIN))
1110 goto again;
1111
1112 return ret;
1113}
1114EXPORT_SYMBOL(ida_simple_get);
1115
1116/**
1117 * ida_simple_remove - remove an allocated id.
1118 * @ida: the (initialized) ida.
1119 * @id: the id returned by ida_simple_get.
1120 */
1121void ida_simple_remove(struct ida *ida, unsigned int id)
1122{
Tejun Heo46cbc1d2011-11-02 13:38:46 -07001123 unsigned long flags;
1124
Rusty Russell88eca022011-08-03 16:21:06 -07001125 BUG_ON((int)id < 0);
Tejun Heo46cbc1d2011-11-02 13:38:46 -07001126 spin_lock_irqsave(&simple_ida_lock, flags);
Rusty Russell88eca022011-08-03 16:21:06 -07001127 ida_remove(ida, id);
Tejun Heo46cbc1d2011-11-02 13:38:46 -07001128 spin_unlock_irqrestore(&simple_ida_lock, flags);
Rusty Russell88eca022011-08-03 16:21:06 -07001129}
1130EXPORT_SYMBOL(ida_simple_remove);
1131
1132/**
Tejun Heo72dba582007-06-14 03:45:13 +09001133 * ida_init - initialize ida handle
1134 * @ida: ida handle
1135 *
1136 * This function is use to set up the handle (@ida) that you will pass
1137 * to the rest of the functions.
1138 */
1139void ida_init(struct ida *ida)
1140{
1141 memset(ida, 0, sizeof(struct ida));
1142 idr_init(&ida->idr);
1143
1144}
1145EXPORT_SYMBOL(ida_init);