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1/*
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 *
9 * Modified by Nadia Derbey to make it RCU safe.
10 *
11 * Small id to pointer translation service.
12 *
13 * It uses a radix tree like structure as a sparse array indexed
14 * by the id to obtain the pointer. The bitmap makes allocating
15 * a new id quick.
16 *
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 */
22
23#ifndef TEST // to test in user space...
24#include <linux/slab.h>
25#include <linux/init.h>
26#include <linux/export.h>
27#endif
28#include <linux/err.h>
29#include <linux/string.h>
30#include <linux/idr.h>
31#include <linux/spinlock.h>
32#include <linux/percpu.h>
33
34#define MAX_IDR_SHIFT (sizeof(int) * 8 - 1)
35#define MAX_IDR_BIT (1U << MAX_IDR_SHIFT)
36
37/* Leave the possibility of an incomplete final layer */
38#define MAX_IDR_LEVEL ((MAX_IDR_SHIFT + IDR_BITS - 1) / IDR_BITS)
39
40/* Number of id_layer structs to leave in free list */
41#define MAX_IDR_FREE (MAX_IDR_LEVEL * 2)
42
43static struct kmem_cache *idr_layer_cache;
44static DEFINE_PER_CPU(struct idr_layer *, idr_preload_head);
45static DEFINE_PER_CPU(int, idr_preload_cnt);
46static DEFINE_SPINLOCK(simple_ida_lock);
47
48/* the maximum ID which can be allocated given idr->layers */
49static int idr_max(int layers)
50{
51 int bits = min_t(int, layers * IDR_BITS, MAX_IDR_SHIFT);
52
53 return (1 << bits) - 1;
54}
55
56/*
57 * Prefix mask for an idr_layer at @layer. For layer 0, the prefix mask is
58 * all bits except for the lower IDR_BITS. For layer 1, 2 * IDR_BITS, and
59 * so on.
60 */
61static int idr_layer_prefix_mask(int layer)
62{
63 return ~idr_max(layer + 1);
64}
65
66static struct idr_layer *get_from_free_list(struct idr *idp)
67{
68 struct idr_layer *p;
69 unsigned long flags;
70
71 spin_lock_irqsave(&idp->lock, flags);
72 if ((p = idp->id_free)) {
73 idp->id_free = p->ary[0];
74 idp->id_free_cnt--;
75 p->ary[0] = NULL;
76 }
77 spin_unlock_irqrestore(&idp->lock, flags);
78 return(p);
79}
80
81/**
82 * idr_layer_alloc - allocate a new idr_layer
83 * @gfp_mask: allocation mask
84 * @layer_idr: optional idr to allocate from
85 *
86 * If @layer_idr is %NULL, directly allocate one using @gfp_mask or fetch
87 * one from the per-cpu preload buffer. If @layer_idr is not %NULL, fetch
88 * an idr_layer from @idr->id_free.
89 *
90 * @layer_idr is to maintain backward compatibility with the old alloc
91 * interface - idr_pre_get() and idr_get_new*() - and will be removed
92 * together with per-pool preload buffer.
93 */
94static struct idr_layer *idr_layer_alloc(gfp_t gfp_mask, struct idr *layer_idr)
95{
96 struct idr_layer *new;
97
98 /* this is the old path, bypass to get_from_free_list() */
99 if (layer_idr)
100 return get_from_free_list(layer_idr);
101
102 /*
103 * Try to allocate directly from kmem_cache. We want to try this
104 * before preload buffer; otherwise, non-preloading idr_alloc()
105 * users will end up taking advantage of preloading ones. As the
106 * following is allowed to fail for preloaded cases, suppress
107 * warning this time.
108 */
109 new = kmem_cache_zalloc(idr_layer_cache, gfp_mask | __GFP_NOWARN);
110 if (new)
111 return new;
112
113 /*
114 * Try to fetch one from the per-cpu preload buffer if in process
115 * context. See idr_preload() for details.
116 */
117 if (!in_interrupt()) {
118 preempt_disable();
119 new = __this_cpu_read(idr_preload_head);
120 if (new) {
121 __this_cpu_write(idr_preload_head, new->ary[0]);
122 __this_cpu_dec(idr_preload_cnt);
123 new->ary[0] = NULL;
124 }
125 preempt_enable();
126 if (new)
127 return new;
128 }
129
130 /*
131 * Both failed. Try kmem_cache again w/o adding __GFP_NOWARN so
132 * that memory allocation failure warning is printed as intended.
133 */
134 return kmem_cache_zalloc(idr_layer_cache, gfp_mask);
135}
136
137static void idr_layer_rcu_free(struct rcu_head *head)
138{
139 struct idr_layer *layer;
140
141 layer = container_of(head, struct idr_layer, rcu_head);
142 kmem_cache_free(idr_layer_cache, layer);
143}
144
145static inline void free_layer(struct idr *idr, struct idr_layer *p)
146{
147 if (idr->hint == p)
148 RCU_INIT_POINTER(idr->hint, NULL);
149 call_rcu(&p->rcu_head, idr_layer_rcu_free);
150}
151
152/* only called when idp->lock is held */
153static void __move_to_free_list(struct idr *idp, struct idr_layer *p)
154{
155 p->ary[0] = idp->id_free;
156 idp->id_free = p;
157 idp->id_free_cnt++;
158}
159
160static void move_to_free_list(struct idr *idp, struct idr_layer *p)
161{
162 unsigned long flags;
163
164 /*
165 * Depends on the return element being zeroed.
166 */
167 spin_lock_irqsave(&idp->lock, flags);
168 __move_to_free_list(idp, p);
169 spin_unlock_irqrestore(&idp->lock, flags);
170}
171
172static void idr_mark_full(struct idr_layer **pa, int id)
173{
174 struct idr_layer *p = pa[0];
175 int l = 0;
176
177 __set_bit(id & IDR_MASK, p->bitmap);
178 /*
179 * If this layer is full mark the bit in the layer above to
180 * show that this part of the radix tree is full. This may
181 * complete the layer above and require walking up the radix
182 * tree.
183 */
184 while (bitmap_full(p->bitmap, IDR_SIZE)) {
185 if (!(p = pa[++l]))
186 break;
187 id = id >> IDR_BITS;
188 __set_bit((id & IDR_MASK), p->bitmap);
189 }
190}
191
192static int __idr_pre_get(struct idr *idp, gfp_t gfp_mask)
193{
194 while (idp->id_free_cnt < MAX_IDR_FREE) {
195 struct idr_layer *new;
196 new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
197 if (new == NULL)
198 return (0);
199 move_to_free_list(idp, new);
200 }
201 return 1;
202}
203
204/**
205 * sub_alloc - try to allocate an id without growing the tree depth
206 * @idp: idr handle
207 * @starting_id: id to start search at
208 * @pa: idr_layer[MAX_IDR_LEVEL] used as backtrack buffer
209 * @gfp_mask: allocation mask for idr_layer_alloc()
210 * @layer_idr: optional idr passed to idr_layer_alloc()
211 *
212 * Allocate an id in range [@starting_id, INT_MAX] from @idp without
213 * growing its depth. Returns
214 *
215 * the allocated id >= 0 if successful,
216 * -EAGAIN if the tree needs to grow for allocation to succeed,
217 * -ENOSPC if the id space is exhausted,
218 * -ENOMEM if more idr_layers need to be allocated.
219 */
220static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa,
221 gfp_t gfp_mask, struct idr *layer_idr)
222{
223 int n, m, sh;
224 struct idr_layer *p, *new;
225 int l, id, oid;
226
227 id = *starting_id;
228 restart:
229 p = idp->top;
230 l = idp->layers;
231 pa[l--] = NULL;
232 while (1) {
233 /*
234 * We run around this while until we reach the leaf node...
235 */
236 n = (id >> (IDR_BITS*l)) & IDR_MASK;
237 m = find_next_zero_bit(p->bitmap, IDR_SIZE, n);
238 if (m == IDR_SIZE) {
239 /* no space available go back to previous layer. */
240 l++;
241 oid = id;
242 id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1;
243
244 /* if already at the top layer, we need to grow */
245 if (id > idr_max(idp->layers)) {
246 *starting_id = id;
247 return -EAGAIN;
248 }
249 p = pa[l];
250 BUG_ON(!p);
251
252 /* If we need to go up one layer, continue the
253 * loop; otherwise, restart from the top.
254 */
255 sh = IDR_BITS * (l + 1);
256 if (oid >> sh == id >> sh)
257 continue;
258 else
259 goto restart;
260 }
261 if (m != n) {
262 sh = IDR_BITS*l;
263 id = ((id >> sh) ^ n ^ m) << sh;
264 }
265 if ((id >= MAX_IDR_BIT) || (id < 0))
266 return -ENOSPC;
267 if (l == 0)
268 break;
269 /*
270 * Create the layer below if it is missing.
271 */
272 if (!p->ary[m]) {
273 new = idr_layer_alloc(gfp_mask, layer_idr);
274 if (!new)
275 return -ENOMEM;
276 new->layer = l-1;
277 new->prefix = id & idr_layer_prefix_mask(new->layer);
278 rcu_assign_pointer(p->ary[m], new);
279 p->count++;
280 }
281 pa[l--] = p;
282 p = p->ary[m];
283 }
284
285 pa[l] = p;
286 return id;
287}
288
289static int idr_get_empty_slot(struct idr *idp, int starting_id,
290 struct idr_layer **pa, gfp_t gfp_mask,
291 struct idr *layer_idr)
292{
293 struct idr_layer *p, *new;
294 int layers, v, id;
295 unsigned long flags;
296
297 id = starting_id;
298build_up:
299 p = idp->top;
300 layers = idp->layers;
301 if (unlikely(!p)) {
302 if (!(p = idr_layer_alloc(gfp_mask, layer_idr)))
303 return -ENOMEM;
304 p->layer = 0;
305 layers = 1;
306 }
307 /*
308 * Add a new layer to the top of the tree if the requested
309 * id is larger than the currently allocated space.
310 */
311 while (id > idr_max(layers)) {
312 layers++;
313 if (!p->count) {
314 /* special case: if the tree is currently empty,
315 * then we grow the tree by moving the top node
316 * upwards.
317 */
318 p->layer++;
319 WARN_ON_ONCE(p->prefix);
320 continue;
321 }
322 if (!(new = idr_layer_alloc(gfp_mask, layer_idr))) {
323 /*
324 * The allocation failed. If we built part of
325 * the structure tear it down.
326 */
327 spin_lock_irqsave(&idp->lock, flags);
328 for (new = p; p && p != idp->top; new = p) {
329 p = p->ary[0];
330 new->ary[0] = NULL;
331 new->count = 0;
332 bitmap_clear(new->bitmap, 0, IDR_SIZE);
333 __move_to_free_list(idp, new);
334 }
335 spin_unlock_irqrestore(&idp->lock, flags);
336 return -ENOMEM;
337 }
338 new->ary[0] = p;
339 new->count = 1;
340 new->layer = layers-1;
341 new->prefix = id & idr_layer_prefix_mask(new->layer);
342 if (bitmap_full(p->bitmap, IDR_SIZE))
343 __set_bit(0, new->bitmap);
344 p = new;
345 }
346 rcu_assign_pointer(idp->top, p);
347 idp->layers = layers;
348 v = sub_alloc(idp, &id, pa, gfp_mask, layer_idr);
349 if (v == -EAGAIN)
350 goto build_up;
351 return(v);
352}
353
354/*
355 * @id and @pa are from a successful allocation from idr_get_empty_slot().
356 * Install the user pointer @ptr and mark the slot full.
357 */
358static void idr_fill_slot(struct idr *idr, void *ptr, int id,
359 struct idr_layer **pa)
360{
361 /* update hint used for lookup, cleared from free_layer() */
362 rcu_assign_pointer(idr->hint, pa[0]);
363
364 rcu_assign_pointer(pa[0]->ary[id & IDR_MASK], (struct idr_layer *)ptr);
365 pa[0]->count++;
366 idr_mark_full(pa, id);
367}
368
369
370/**
371 * idr_preload - preload for idr_alloc()
372 * @gfp_mask: allocation mask to use for preloading
373 *
374 * Preload per-cpu layer buffer for idr_alloc(). Can only be used from
375 * process context and each idr_preload() invocation should be matched with
376 * idr_preload_end(). Note that preemption is disabled while preloaded.
377 *
378 * The first idr_alloc() in the preloaded section can be treated as if it
379 * were invoked with @gfp_mask used for preloading. This allows using more
380 * permissive allocation masks for idrs protected by spinlocks.
381 *
382 * For example, if idr_alloc() below fails, the failure can be treated as
383 * if idr_alloc() were called with GFP_KERNEL rather than GFP_NOWAIT.
384 *
385 * idr_preload(GFP_KERNEL);
386 * spin_lock(lock);
387 *
388 * id = idr_alloc(idr, ptr, start, end, GFP_NOWAIT);
389 *
390 * spin_unlock(lock);
391 * idr_preload_end();
392 * if (id < 0)
393 * error;
394 */
395void idr_preload(gfp_t gfp_mask)
396{
397 /*
398 * Consuming preload buffer from non-process context breaks preload
399 * allocation guarantee. Disallow usage from those contexts.
400 */
401 WARN_ON_ONCE(in_interrupt());
402 might_sleep_if(gfpflags_allow_blocking(gfp_mask));
403
404 preempt_disable();
405
406 /*
407 * idr_alloc() is likely to succeed w/o full idr_layer buffer and
408 * return value from idr_alloc() needs to be checked for failure
409 * anyway. Silently give up if allocation fails. The caller can
410 * treat failures from idr_alloc() as if idr_alloc() were called
411 * with @gfp_mask which should be enough.
412 */
413 while (__this_cpu_read(idr_preload_cnt) < MAX_IDR_FREE) {
414 struct idr_layer *new;
415
416 preempt_enable();
417 new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
418 preempt_disable();
419 if (!new)
420 break;
421
422 /* link the new one to per-cpu preload list */
423 new->ary[0] = __this_cpu_read(idr_preload_head);
424 __this_cpu_write(idr_preload_head, new);
425 __this_cpu_inc(idr_preload_cnt);
426 }
427}
428EXPORT_SYMBOL(idr_preload);
429
430/**
431 * idr_alloc - allocate new idr entry
432 * @idr: the (initialized) idr
433 * @ptr: pointer to be associated with the new id
434 * @start: the minimum id (inclusive)
435 * @end: the maximum id (exclusive, <= 0 for max)
436 * @gfp_mask: memory allocation flags
437 *
438 * Allocate an id in [start, end) and associate it with @ptr. If no ID is
439 * available in the specified range, returns -ENOSPC. On memory allocation
440 * failure, returns -ENOMEM.
441 *
442 * Note that @end is treated as max when <= 0. This is to always allow
443 * using @start + N as @end as long as N is inside integer range.
444 *
445 * The user is responsible for exclusively synchronizing all operations
446 * which may modify @idr. However, read-only accesses such as idr_find()
447 * or iteration can be performed under RCU read lock provided the user
448 * destroys @ptr in RCU-safe way after removal from idr.
449 */
450int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask)
451{
452 int max = end > 0 ? end - 1 : INT_MAX; /* inclusive upper limit */
453 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
454 int id;
455
456 might_sleep_if(gfpflags_allow_blocking(gfp_mask));
457
458 /* sanity checks */
459 if (WARN_ON_ONCE(start < 0))
460 return -EINVAL;
461 if (unlikely(max < start))
462 return -ENOSPC;
463
464 /* allocate id */
465 id = idr_get_empty_slot(idr, start, pa, gfp_mask, NULL);
466 if (unlikely(id < 0))
467 return id;
468 if (unlikely(id > max))
469 return -ENOSPC;
470
471 idr_fill_slot(idr, ptr, id, pa);
472 return id;
473}
474EXPORT_SYMBOL_GPL(idr_alloc);
475
476/**
477 * idr_alloc_cyclic - allocate new idr entry in a cyclical fashion
478 * @idr: the (initialized) idr
479 * @ptr: pointer to be associated with the new id
480 * @start: the minimum id (inclusive)
481 * @end: the maximum id (exclusive, <= 0 for max)
482 * @gfp_mask: memory allocation flags
483 *
484 * Essentially the same as idr_alloc, but prefers to allocate progressively
485 * higher ids if it can. If the "cur" counter wraps, then it will start again
486 * at the "start" end of the range and allocate one that has already been used.
487 */
488int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end,
489 gfp_t gfp_mask)
490{
491 int id;
492
493 id = idr_alloc(idr, ptr, max(start, idr->cur), end, gfp_mask);
494 if (id == -ENOSPC)
495 id = idr_alloc(idr, ptr, start, end, gfp_mask);
496
497 if (likely(id >= 0))
498 idr->cur = id + 1;
499 return id;
500}
501EXPORT_SYMBOL(idr_alloc_cyclic);
502
503static void idr_remove_warning(int id)
504{
505 WARN(1, "idr_remove called for id=%d which is not allocated.\n", id);
506}
507
508static void sub_remove(struct idr *idp, int shift, int id)
509{
510 struct idr_layer *p = idp->top;
511 struct idr_layer **pa[MAX_IDR_LEVEL + 1];
512 struct idr_layer ***paa = &pa[0];
513 struct idr_layer *to_free;
514 int n;
515
516 *paa = NULL;
517 *++paa = &idp->top;
518
519 while ((shift > 0) && p) {
520 n = (id >> shift) & IDR_MASK;
521 __clear_bit(n, p->bitmap);
522 *++paa = &p->ary[n];
523 p = p->ary[n];
524 shift -= IDR_BITS;
525 }
526 n = id & IDR_MASK;
527 if (likely(p != NULL && test_bit(n, p->bitmap))) {
528 __clear_bit(n, p->bitmap);
529 RCU_INIT_POINTER(p->ary[n], NULL);
530 to_free = NULL;
531 while(*paa && ! --((**paa)->count)){
532 if (to_free)
533 free_layer(idp, to_free);
534 to_free = **paa;
535 **paa-- = NULL;
536 }
537 if (!*paa)
538 idp->layers = 0;
539 if (to_free)
540 free_layer(idp, to_free);
541 } else
542 idr_remove_warning(id);
543}
544
545/**
546 * idr_remove - remove the given id and free its slot
547 * @idp: idr handle
548 * @id: unique key
549 */
550void idr_remove(struct idr *idp, int id)
551{
552 struct idr_layer *p;
553 struct idr_layer *to_free;
554
555 if (id < 0)
556 return;
557
558 if (id > idr_max(idp->layers)) {
559 idr_remove_warning(id);
560 return;
561 }
562
563 sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
564 if (idp->top && idp->top->count == 1 && (idp->layers > 1) &&
565 idp->top->ary[0]) {
566 /*
567 * Single child at leftmost slot: we can shrink the tree.
568 * This level is not needed anymore since when layers are
569 * inserted, they are inserted at the top of the existing
570 * tree.
571 */
572 to_free = idp->top;
573 p = idp->top->ary[0];
574 rcu_assign_pointer(idp->top, p);
575 --idp->layers;
576 to_free->count = 0;
577 bitmap_clear(to_free->bitmap, 0, IDR_SIZE);
578 free_layer(idp, to_free);
579 }
580}
581EXPORT_SYMBOL(idr_remove);
582
583static void __idr_remove_all(struct idr *idp)
584{
585 int n, id, max;
586 int bt_mask;
587 struct idr_layer *p;
588 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
589 struct idr_layer **paa = &pa[0];
590
591 n = idp->layers * IDR_BITS;
592 *paa = idp->top;
593 RCU_INIT_POINTER(idp->top, NULL);
594 max = idr_max(idp->layers);
595
596 id = 0;
597 while (id >= 0 && id <= max) {
598 p = *paa;
599 while (n > IDR_BITS && p) {
600 n -= IDR_BITS;
601 p = p->ary[(id >> n) & IDR_MASK];
602 *++paa = p;
603 }
604
605 bt_mask = id;
606 id += 1 << n;
607 /* Get the highest bit that the above add changed from 0->1. */
608 while (n < fls(id ^ bt_mask)) {
609 if (*paa)
610 free_layer(idp, *paa);
611 n += IDR_BITS;
612 --paa;
613 }
614 }
615 idp->layers = 0;
616}
617
618/**
619 * idr_destroy - release all cached layers within an idr tree
620 * @idp: idr handle
621 *
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 necessary, then idr_destroy() to
629 * free up the id mappings and cached idr_layers.
630 */
631void idr_destroy(struct idr *idp)
632{
633 __idr_remove_all(idp);
634
635 while (idp->id_free_cnt) {
636 struct idr_layer *p = get_from_free_list(idp);
637 kmem_cache_free(idr_layer_cache, p);
638 }
639}
640EXPORT_SYMBOL(idr_destroy);
641
642void *idr_find_slowpath(struct idr *idp, int id)
643{
644 int n;
645 struct idr_layer *p;
646
647 if (id < 0)
648 return NULL;
649
650 p = rcu_dereference_raw(idp->top);
651 if (!p)
652 return NULL;
653 n = (p->layer+1) * IDR_BITS;
654
655 if (id > idr_max(p->layer + 1))
656 return NULL;
657 BUG_ON(n == 0);
658
659 while (n > 0 && p) {
660 n -= IDR_BITS;
661 BUG_ON(n != p->layer*IDR_BITS);
662 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
663 }
664 return((void *)p);
665}
666EXPORT_SYMBOL(idr_find_slowpath);
667
668/**
669 * 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
682 * than %0, we break out and return that value.
683 *
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;
691 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
692 struct idr_layer **paa = &pa[0];
693
694 n = idp->layers * IDR_BITS;
695 *paa = rcu_dereference_raw(idp->top);
696 max = idr_max(idp->layers);
697
698 id = 0;
699 while (id >= 0 && id <= max) {
700 p = *paa;
701 while (n > 0 && p) {
702 n -= IDR_BITS;
703 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
704 *++paa = p;
705 }
706
707 if (p) {
708 error = fn(id, (void *)p, data);
709 if (error)
710 break;
711 }
712
713 id += 1 << n;
714 while (n < fls(id)) {
715 n += IDR_BITS;
716 --paa;
717 }
718 }
719
720 return error;
721}
722EXPORT_SYMBOL(idr_for_each);
723
724/**
725 * idr_get_next - lookup next object of id to given id.
726 * @idp: idr handle
727 * @nextidp: pointer to lookup key
728 *
729 * Returns pointer to registered object with id, which is next number to
730 * given id. After being looked up, *@nextidp will be updated for the next
731 * iteration.
732 *
733 * This function can be called under rcu_read_lock(), given that the leaf
734 * pointers lifetimes are correctly managed.
735 */
736void *idr_get_next(struct idr *idp, int *nextidp)
737{
738 struct idr_layer *p, *pa[MAX_IDR_LEVEL + 1];
739 struct idr_layer **paa = &pa[0];
740 int id = *nextidp;
741 int n, max;
742
743 /* find first ent */
744 p = *paa = rcu_dereference_raw(idp->top);
745 if (!p)
746 return NULL;
747 n = (p->layer + 1) * IDR_BITS;
748 max = idr_max(p->layer + 1);
749
750 while (id >= 0 && id <= max) {
751 p = *paa;
752 while (n > 0 && p) {
753 n -= IDR_BITS;
754 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
755 *++paa = p;
756 }
757
758 if (p) {
759 *nextidp = id;
760 return p;
761 }
762
763 /*
764 * Proceed to the next layer at the current level. Unlike
765 * idr_for_each(), @id isn't guaranteed to be aligned to
766 * layer boundary at this point and adding 1 << n may
767 * incorrectly skip IDs. Make sure we jump to the
768 * beginning of the next layer using round_up().
769 */
770 id = round_up(id + 1, 1 << n);
771 while (n < fls(id)) {
772 n += IDR_BITS;
773 --paa;
774 }
775 }
776 return NULL;
777}
778EXPORT_SYMBOL(idr_get_next);
779
780
781/**
782 * idr_replace - replace pointer for given id
783 * @idp: idr handle
784 * @ptr: pointer you want associated with the id
785 * @id: lookup key
786 *
787 * Replace the pointer registered with an id and return the old value.
788 * A %-ENOENT return indicates that @id was not found.
789 * A %-EINVAL return indicates that @id was not within valid constraints.
790 *
791 * The caller must serialize with writers.
792 */
793void *idr_replace(struct idr *idp, void *ptr, int id)
794{
795 int n;
796 struct idr_layer *p, *old_p;
797
798 if (id < 0)
799 return ERR_PTR(-EINVAL);
800
801 p = idp->top;
802 if (!p)
803 return ERR_PTR(-ENOENT);
804
805 if (id > idr_max(p->layer + 1))
806 return ERR_PTR(-ENOENT);
807
808 n = p->layer * IDR_BITS;
809 while ((n > 0) && p) {
810 p = p->ary[(id >> n) & IDR_MASK];
811 n -= IDR_BITS;
812 }
813
814 n = id & IDR_MASK;
815 if (unlikely(p == NULL || !test_bit(n, p->bitmap)))
816 return ERR_PTR(-ENOENT);
817
818 old_p = p->ary[n];
819 rcu_assign_pointer(p->ary[n], ptr);
820
821 return old_p;
822}
823EXPORT_SYMBOL(idr_replace);
824
825void __init idr_init_cache(void)
826{
827 idr_layer_cache = kmem_cache_create("idr_layer_cache",
828 sizeof(struct idr_layer), 0, SLAB_PANIC, NULL);
829}
830
831/**
832 * idr_init - initialize idr handle
833 * @idp: idr handle
834 *
835 * This function is use to set up the handle (@idp) that you will pass
836 * to the rest of the functions.
837 */
838void idr_init(struct idr *idp)
839{
840 memset(idp, 0, sizeof(struct idr));
841 spin_lock_init(&idp->lock);
842}
843EXPORT_SYMBOL(idr_init);
844
845static int idr_has_entry(int id, void *p, void *data)
846{
847 return 1;
848}
849
850bool idr_is_empty(struct idr *idp)
851{
852 return !idr_for_each(idp, idr_has_entry, NULL);
853}
854EXPORT_SYMBOL(idr_is_empty);
855
856/**
857 * DOC: IDA description
858 * IDA - IDR based ID allocator
859 *
860 * This is id allocator without id -> pointer translation. Memory
861 * usage is much lower than full blown idr because each id only
862 * occupies a bit. ida uses a custom leaf node which contains
863 * IDA_BITMAP_BITS slots.
864 *
865 * 2007-04-25 written by Tejun Heo <htejun@gmail.com>
866 */
867
868static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap)
869{
870 unsigned long flags;
871
872 if (!ida->free_bitmap) {
873 spin_lock_irqsave(&ida->idr.lock, flags);
874 if (!ida->free_bitmap) {
875 ida->free_bitmap = bitmap;
876 bitmap = NULL;
877 }
878 spin_unlock_irqrestore(&ida->idr.lock, flags);
879 }
880
881 kfree(bitmap);
882}
883
884/**
885 * ida_pre_get - reserve resources for ida allocation
886 * @ida: ida handle
887 * @gfp_mask: memory allocation flag
888 *
889 * This function should be called prior to locking and calling the
890 * following function. It preallocates enough memory to satisfy the
891 * worst possible allocation.
892 *
893 * If the system is REALLY out of memory this function returns %0,
894 * otherwise %1.
895 */
896int ida_pre_get(struct ida *ida, gfp_t gfp_mask)
897{
898 /* allocate idr_layers */
899 if (!__idr_pre_get(&ida->idr, gfp_mask))
900 return 0;
901
902 /* allocate free_bitmap */
903 if (!ida->free_bitmap) {
904 struct ida_bitmap *bitmap;
905
906 bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask);
907 if (!bitmap)
908 return 0;
909
910 free_bitmap(ida, bitmap);
911 }
912
913 return 1;
914}
915EXPORT_SYMBOL(ida_pre_get);
916
917/**
918 * ida_get_new_above - allocate new ID above or equal to a start id
919 * @ida: ida handle
920 * @starting_id: id to start search at
921 * @p_id: pointer to the allocated handle
922 *
923 * Allocate new ID above or equal to @starting_id. It should be called
924 * with any required locks.
925 *
926 * If memory is required, it will return %-EAGAIN, you should unlock
927 * and go back to the ida_pre_get() call. If the ida is full, it will
928 * return %-ENOSPC.
929 *
930 * @p_id returns a value in the range @starting_id ... %0x7fffffff.
931 */
932int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
933{
934 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
935 struct ida_bitmap *bitmap;
936 unsigned long flags;
937 int idr_id = starting_id / IDA_BITMAP_BITS;
938 int offset = starting_id % IDA_BITMAP_BITS;
939 int t, id;
940
941 restart:
942 /* get vacant slot */
943 t = idr_get_empty_slot(&ida->idr, idr_id, pa, 0, &ida->idr);
944 if (t < 0)
945 return t == -ENOMEM ? -EAGAIN : t;
946
947 if (t * IDA_BITMAP_BITS >= MAX_IDR_BIT)
948 return -ENOSPC;
949
950 if (t != idr_id)
951 offset = 0;
952 idr_id = t;
953
954 /* if bitmap isn't there, create a new one */
955 bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK];
956 if (!bitmap) {
957 spin_lock_irqsave(&ida->idr.lock, flags);
958 bitmap = ida->free_bitmap;
959 ida->free_bitmap = NULL;
960 spin_unlock_irqrestore(&ida->idr.lock, flags);
961
962 if (!bitmap)
963 return -EAGAIN;
964
965 memset(bitmap, 0, sizeof(struct ida_bitmap));
966 rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK],
967 (void *)bitmap);
968 pa[0]->count++;
969 }
970
971 /* lookup for empty slot */
972 t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset);
973 if (t == IDA_BITMAP_BITS) {
974 /* no empty slot after offset, continue to the next chunk */
975 idr_id++;
976 offset = 0;
977 goto restart;
978 }
979
980 id = idr_id * IDA_BITMAP_BITS + t;
981 if (id >= MAX_IDR_BIT)
982 return -ENOSPC;
983
984 __set_bit(t, bitmap->bitmap);
985 if (++bitmap->nr_busy == IDA_BITMAP_BITS)
986 idr_mark_full(pa, idr_id);
987
988 *p_id = id;
989
990 /* Each leaf node can handle nearly a thousand slots and the
991 * whole idea of ida is to have small memory foot print.
992 * Throw away extra resources one by one after each successful
993 * allocation.
994 */
995 if (ida->idr.id_free_cnt || ida->free_bitmap) {
996 struct idr_layer *p = get_from_free_list(&ida->idr);
997 if (p)
998 kmem_cache_free(idr_layer_cache, p);
999 }
1000
1001 return 0;
1002}
1003EXPORT_SYMBOL(ida_get_new_above);
1004
1005/**
1006 * ida_remove - remove the given ID
1007 * @ida: ida handle
1008 * @id: ID to free
1009 */
1010void ida_remove(struct ida *ida, int id)
1011{
1012 struct idr_layer *p = ida->idr.top;
1013 int shift = (ida->idr.layers - 1) * IDR_BITS;
1014 int idr_id = id / IDA_BITMAP_BITS;
1015 int offset = id % IDA_BITMAP_BITS;
1016 int n;
1017 struct ida_bitmap *bitmap;
1018
1019 if (idr_id > idr_max(ida->idr.layers))
1020 goto err;
1021
1022 /* clear full bits while looking up the leaf idr_layer */
1023 while ((shift > 0) && p) {
1024 n = (idr_id >> shift) & IDR_MASK;
1025 __clear_bit(n, p->bitmap);
1026 p = p->ary[n];
1027 shift -= IDR_BITS;
1028 }
1029
1030 if (p == NULL)
1031 goto err;
1032
1033 n = idr_id & IDR_MASK;
1034 __clear_bit(n, p->bitmap);
1035
1036 bitmap = (void *)p->ary[n];
1037 if (!bitmap || !test_bit(offset, bitmap->bitmap))
1038 goto err;
1039
1040 /* update bitmap and remove it if empty */
1041 __clear_bit(offset, bitmap->bitmap);
1042 if (--bitmap->nr_busy == 0) {
1043 __set_bit(n, p->bitmap); /* to please idr_remove() */
1044 idr_remove(&ida->idr, idr_id);
1045 free_bitmap(ida, bitmap);
1046 }
1047
1048 return;
1049
1050 err:
1051 WARN(1, "ida_remove called for id=%d which is not allocated.\n", id);
1052}
1053EXPORT_SYMBOL(ida_remove);
1054
1055/**
1056 * ida_destroy - release all cached layers within an ida tree
1057 * @ida: ida handle
1058 */
1059void ida_destroy(struct ida *ida)
1060{
1061 idr_destroy(&ida->idr);
1062 kfree(ida->free_bitmap);
1063}
1064EXPORT_SYMBOL(ida_destroy);
1065
1066/**
1067 * ida_simple_get - get a new id.
1068 * @ida: the (initialized) ida.
1069 * @start: the minimum id (inclusive, < 0x8000000)
1070 * @end: the maximum id (exclusive, < 0x8000000 or 0)
1071 * @gfp_mask: memory allocation flags
1072 *
1073 * Allocates an id in the range start <= id < end, or returns -ENOSPC.
1074 * On memory allocation failure, returns -ENOMEM.
1075 *
1076 * Use ida_simple_remove() to get rid of an id.
1077 */
1078int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
1079 gfp_t gfp_mask)
1080{
1081 int ret, id;
1082 unsigned int max;
1083 unsigned long flags;
1084
1085 BUG_ON((int)start < 0);
1086 BUG_ON((int)end < 0);
1087
1088 if (end == 0)
1089 max = 0x80000000;
1090 else {
1091 BUG_ON(end < start);
1092 max = end - 1;
1093 }
1094
1095again:
1096 if (!ida_pre_get(ida, gfp_mask))
1097 return -ENOMEM;
1098
1099 spin_lock_irqsave(&simple_ida_lock, flags);
1100 ret = ida_get_new_above(ida, start, &id);
1101 if (!ret) {
1102 if (id > max) {
1103 ida_remove(ida, id);
1104 ret = -ENOSPC;
1105 } else {
1106 ret = id;
1107 }
1108 }
1109 spin_unlock_irqrestore(&simple_ida_lock, flags);
1110
1111 if (unlikely(ret == -EAGAIN))
1112 goto again;
1113
1114 return ret;
1115}
1116EXPORT_SYMBOL(ida_simple_get);
1117
1118/**
1119 * ida_simple_remove - remove an allocated id.
1120 * @ida: the (initialized) ida.
1121 * @id: the id returned by ida_simple_get.
1122 */
1123void ida_simple_remove(struct ida *ida, unsigned int id)
1124{
1125 unsigned long flags;
1126
1127 BUG_ON((int)id < 0);
1128 spin_lock_irqsave(&simple_ida_lock, flags);
1129 ida_remove(ida, id);
1130 spin_unlock_irqrestore(&simple_ida_lock, flags);
1131}
1132EXPORT_SYMBOL(ida_simple_remove);
1133
1134/**
1135 * ida_init - initialize ida handle
1136 * @ida: ida handle
1137 *
1138 * This function is use to set up the handle (@ida) that you will pass
1139 * to the rest of the functions.
1140 */
1141void ida_init(struct ida *ida)
1142{
1143 memset(ida, 0, sizeof(struct ida));
1144 idr_init(&ida->idr);
1145
1146}
1147EXPORT_SYMBOL(ida_init);
1/*
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 *
9 * Modified by Nadia Derbey to make it RCU safe.
10 *
11 * Small id to pointer translation service.
12 *
13 * It uses a radix tree like structure as a sparse array indexed
14 * by the id to obtain the pointer. The bitmap makes allocating
15 * a new id quick.
16 *
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
22 * You can release ids at any time. When all ids are released, most of
23 * the memory is returned (we keep IDR_FREE_MAX) in a local pool so we
24 * don't need to go to the memory "store" during an id allocate, just
25 * 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
34#include <linux/err.h>
35#include <linux/string.h>
36#include <linux/idr.h>
37#include <linux/spinlock.h>
38
39static struct kmem_cache *idr_layer_cache;
40static DEFINE_SPINLOCK(simple_ida_lock);
41
42static struct idr_layer *get_from_free_list(struct idr *idp)
43{
44 struct idr_layer *p;
45 unsigned long flags;
46
47 spin_lock_irqsave(&idp->lock, flags);
48 if ((p = idp->id_free)) {
49 idp->id_free = p->ary[0];
50 idp->id_free_cnt--;
51 p->ary[0] = NULL;
52 }
53 spin_unlock_irqrestore(&idp->lock, flags);
54 return(p);
55}
56
57static void idr_layer_rcu_free(struct rcu_head *head)
58{
59 struct idr_layer *layer;
60
61 layer = container_of(head, struct idr_layer, rcu_head);
62 kmem_cache_free(idr_layer_cache, layer);
63}
64
65static inline void free_layer(struct idr_layer *p)
66{
67 call_rcu(&p->rcu_head, idr_layer_rcu_free);
68}
69
70/* only called when idp->lock is held */
71static void __move_to_free_list(struct idr *idp, struct idr_layer *p)
72{
73 p->ary[0] = idp->id_free;
74 idp->id_free = p;
75 idp->id_free_cnt++;
76}
77
78static void move_to_free_list(struct idr *idp, struct idr_layer *p)
79{
80 unsigned long flags;
81
82 /*
83 * Depends on the return element being zeroed.
84 */
85 spin_lock_irqsave(&idp->lock, flags);
86 __move_to_free_list(idp, p);
87 spin_unlock_irqrestore(&idp->lock, flags);
88}
89
90static void idr_mark_full(struct idr_layer **pa, int id)
91{
92 struct idr_layer *p = pa[0];
93 int l = 0;
94
95 __set_bit(id & IDR_MASK, &p->bitmap);
96 /*
97 * If this layer is full mark the bit in the layer above to
98 * show that this part of the radix tree is full. This may
99 * complete the layer above and require walking up the radix
100 * tree.
101 */
102 while (p->bitmap == IDR_FULL) {
103 if (!(p = pa[++l]))
104 break;
105 id = id >> IDR_BITS;
106 __set_bit((id & IDR_MASK), &p->bitmap);
107 }
108}
109
110/**
111 * idr_pre_get - reserve resources for idr allocation
112 * @idp: idr handle
113 * @gfp_mask: memory allocation flags
114 *
115 * This function should be called prior to calling the idr_get_new* functions.
116 * It preallocates enough memory to satisfy the worst possible allocation. The
117 * caller should pass in GFP_KERNEL if possible. This of course requires that
118 * no spinning locks be held.
119 *
120 * If the system is REALLY out of memory this function returns %0,
121 * otherwise %1.
122 */
123int idr_pre_get(struct idr *idp, gfp_t gfp_mask)
124{
125 while (idp->id_free_cnt < IDR_FREE_MAX) {
126 struct idr_layer *new;
127 new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
128 if (new == NULL)
129 return (0);
130 move_to_free_list(idp, new);
131 }
132 return 1;
133}
134EXPORT_SYMBOL(idr_pre_get);
135
136static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa)
137{
138 int n, m, sh;
139 struct idr_layer *p, *new;
140 int l, id, oid;
141 unsigned long bm;
142
143 id = *starting_id;
144 restart:
145 p = idp->top;
146 l = idp->layers;
147 pa[l--] = NULL;
148 while (1) {
149 /*
150 * We run around this while until we reach the leaf node...
151 */
152 n = (id >> (IDR_BITS*l)) & IDR_MASK;
153 bm = ~p->bitmap;
154 m = find_next_bit(&bm, IDR_SIZE, n);
155 if (m == IDR_SIZE) {
156 /* no space available go back to previous layer. */
157 l++;
158 oid = id;
159 id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1;
160
161 /* if already at the top layer, we need to grow */
162 if (id >= 1 << (idp->layers * IDR_BITS)) {
163 *starting_id = id;
164 return IDR_NEED_TO_GROW;
165 }
166 p = pa[l];
167 BUG_ON(!p);
168
169 /* If we need to go up one layer, continue the
170 * loop; otherwise, restart from the top.
171 */
172 sh = IDR_BITS * (l + 1);
173 if (oid >> sh == id >> sh)
174 continue;
175 else
176 goto restart;
177 }
178 if (m != n) {
179 sh = IDR_BITS*l;
180 id = ((id >> sh) ^ n ^ m) << sh;
181 }
182 if ((id >= MAX_ID_BIT) || (id < 0))
183 return IDR_NOMORE_SPACE;
184 if (l == 0)
185 break;
186 /*
187 * Create the layer below if it is missing.
188 */
189 if (!p->ary[m]) {
190 new = get_from_free_list(idp);
191 if (!new)
192 return -1;
193 new->layer = l-1;
194 rcu_assign_pointer(p->ary[m], new);
195 p->count++;
196 }
197 pa[l--] = p;
198 p = p->ary[m];
199 }
200
201 pa[l] = p;
202 return id;
203}
204
205static int idr_get_empty_slot(struct idr *idp, int starting_id,
206 struct idr_layer **pa)
207{
208 struct idr_layer *p, *new;
209 int layers, v, id;
210 unsigned long flags;
211
212 id = starting_id;
213build_up:
214 p = idp->top;
215 layers = idp->layers;
216 if (unlikely(!p)) {
217 if (!(p = get_from_free_list(idp)))
218 return -1;
219 p->layer = 0;
220 layers = 1;
221 }
222 /*
223 * Add a new layer to the top of the tree if the requested
224 * id is larger than the currently allocated space.
225 */
226 while ((layers < (MAX_LEVEL - 1)) && (id >= (1 << (layers*IDR_BITS)))) {
227 layers++;
228 if (!p->count) {
229 /* special case: if the tree is currently empty,
230 * then we grow the tree by moving the top node
231 * upwards.
232 */
233 p->layer++;
234 continue;
235 }
236 if (!(new = get_from_free_list(idp))) {
237 /*
238 * The allocation failed. If we built part of
239 * the structure tear it down.
240 */
241 spin_lock_irqsave(&idp->lock, flags);
242 for (new = p; p && p != idp->top; new = p) {
243 p = p->ary[0];
244 new->ary[0] = NULL;
245 new->bitmap = new->count = 0;
246 __move_to_free_list(idp, new);
247 }
248 spin_unlock_irqrestore(&idp->lock, flags);
249 return -1;
250 }
251 new->ary[0] = p;
252 new->count = 1;
253 new->layer = layers-1;
254 if (p->bitmap == IDR_FULL)
255 __set_bit(0, &new->bitmap);
256 p = new;
257 }
258 rcu_assign_pointer(idp->top, p);
259 idp->layers = layers;
260 v = sub_alloc(idp, &id, pa);
261 if (v == IDR_NEED_TO_GROW)
262 goto build_up;
263 return(v);
264}
265
266static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id)
267{
268 struct idr_layer *pa[MAX_LEVEL];
269 int id;
270
271 id = idr_get_empty_slot(idp, starting_id, pa);
272 if (id >= 0) {
273 /*
274 * Successfully found an empty slot. Install the user
275 * pointer and mark the slot full.
276 */
277 rcu_assign_pointer(pa[0]->ary[id & IDR_MASK],
278 (struct idr_layer *)ptr);
279 pa[0]->count++;
280 idr_mark_full(pa, id);
281 }
282
283 return id;
284}
285
286/**
287 * idr_get_new_above - allocate new idr entry above or equal to a start id
288 * @idp: idr handle
289 * @ptr: pointer you want associated with the id
290 * @starting_id: id to start search at
291 * @id: pointer to the allocated handle
292 *
293 * This is the allocate id function. It should be called with any
294 * required locks.
295 *
296 * If allocation from IDR's private freelist fails, idr_get_new_above() will
297 * return %-EAGAIN. The caller should retry the idr_pre_get() call to refill
298 * IDR's preallocation and then retry the idr_get_new_above() call.
299 *
300 * If the idr is full idr_get_new_above() will return %-ENOSPC.
301 *
302 * @id returns a value in the range @starting_id ... %0x7fffffff
303 */
304int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id)
305{
306 int rv;
307
308 rv = idr_get_new_above_int(idp, ptr, starting_id);
309 /*
310 * This is a cheap hack until the IDR code can be fixed to
311 * return proper error values.
312 */
313 if (rv < 0)
314 return _idr_rc_to_errno(rv);
315 *id = rv;
316 return 0;
317}
318EXPORT_SYMBOL(idr_get_new_above);
319
320/**
321 * idr_get_new - allocate new idr entry
322 * @idp: idr handle
323 * @ptr: pointer you want associated with the id
324 * @id: pointer to the allocated handle
325 *
326 * If allocation from IDR's private freelist fails, idr_get_new_above() will
327 * return %-EAGAIN. The caller should retry the idr_pre_get() call to refill
328 * IDR's preallocation and then retry the idr_get_new_above() call.
329 *
330 * If the idr is full idr_get_new_above() will return %-ENOSPC.
331 *
332 * @id returns a value in the range %0 ... %0x7fffffff
333 */
334int idr_get_new(struct idr *idp, void *ptr, int *id)
335{
336 int rv;
337
338 rv = idr_get_new_above_int(idp, ptr, 0);
339 /*
340 * This is a cheap hack until the IDR code can be fixed to
341 * return proper error values.
342 */
343 if (rv < 0)
344 return _idr_rc_to_errno(rv);
345 *id = rv;
346 return 0;
347}
348EXPORT_SYMBOL(idr_get_new);
349
350static void idr_remove_warning(int id)
351{
352 printk(KERN_WARNING
353 "idr_remove called for id=%d which is not allocated.\n", id);
354 dump_stack();
355}
356
357static void sub_remove(struct idr *idp, int shift, int id)
358{
359 struct idr_layer *p = idp->top;
360 struct idr_layer **pa[MAX_LEVEL];
361 struct idr_layer ***paa = &pa[0];
362 struct idr_layer *to_free;
363 int n;
364
365 *paa = NULL;
366 *++paa = &idp->top;
367
368 while ((shift > 0) && p) {
369 n = (id >> shift) & IDR_MASK;
370 __clear_bit(n, &p->bitmap);
371 *++paa = &p->ary[n];
372 p = p->ary[n];
373 shift -= IDR_BITS;
374 }
375 n = id & IDR_MASK;
376 if (likely(p != NULL && test_bit(n, &p->bitmap))){
377 __clear_bit(n, &p->bitmap);
378 rcu_assign_pointer(p->ary[n], NULL);
379 to_free = NULL;
380 while(*paa && ! --((**paa)->count)){
381 if (to_free)
382 free_layer(to_free);
383 to_free = **paa;
384 **paa-- = NULL;
385 }
386 if (!*paa)
387 idp->layers = 0;
388 if (to_free)
389 free_layer(to_free);
390 } else
391 idr_remove_warning(id);
392}
393
394/**
395 * idr_remove - remove the given id and free its slot
396 * @idp: idr handle
397 * @id: unique key
398 */
399void idr_remove(struct idr *idp, int id)
400{
401 struct idr_layer *p;
402 struct idr_layer *to_free;
403
404 /* Mask off upper bits we don't use for the search. */
405 id &= MAX_ID_MASK;
406
407 sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
408 if (idp->top && idp->top->count == 1 && (idp->layers > 1) &&
409 idp->top->ary[0]) {
410 /*
411 * Single child at leftmost slot: we can shrink the tree.
412 * This level is not needed anymore since when layers are
413 * inserted, they are inserted at the top of the existing
414 * tree.
415 */
416 to_free = idp->top;
417 p = idp->top->ary[0];
418 rcu_assign_pointer(idp->top, p);
419 --idp->layers;
420 to_free->bitmap = to_free->count = 0;
421 free_layer(to_free);
422 }
423 while (idp->id_free_cnt >= IDR_FREE_MAX) {
424 p = get_from_free_list(idp);
425 /*
426 * Note: we don't call the rcu callback here, since the only
427 * layers that fall into the freelist are those that have been
428 * preallocated.
429 */
430 kmem_cache_free(idr_layer_cache, p);
431 }
432 return;
433}
434EXPORT_SYMBOL(idr_remove);
435
436/**
437 * idr_remove_all - remove all ids from the given idr tree
438 * @idp: idr handle
439 *
440 * idr_destroy() only frees up unused, cached idp_layers, but this
441 * function will remove all id mappings and leave all idp_layers
442 * unused.
443 *
444 * A typical clean-up sequence for objects stored in an idr tree will
445 * use idr_for_each() to free all objects, if necessay, then
446 * idr_remove_all() to remove all ids, and idr_destroy() to free
447 * up the cached idr_layers.
448 */
449void idr_remove_all(struct idr *idp)
450{
451 int n, id, max;
452 int bt_mask;
453 struct idr_layer *p;
454 struct idr_layer *pa[MAX_LEVEL];
455 struct idr_layer **paa = &pa[0];
456
457 n = idp->layers * IDR_BITS;
458 p = idp->top;
459 rcu_assign_pointer(idp->top, NULL);
460 max = 1 << n;
461
462 id = 0;
463 while (id < max) {
464 while (n > IDR_BITS && p) {
465 n -= IDR_BITS;
466 *paa++ = p;
467 p = p->ary[(id >> n) & IDR_MASK];
468 }
469
470 bt_mask = id;
471 id += 1 << n;
472 /* Get the highest bit that the above add changed from 0->1. */
473 while (n < fls(id ^ bt_mask)) {
474 if (p)
475 free_layer(p);
476 n += IDR_BITS;
477 p = *--paa;
478 }
479 }
480 idp->layers = 0;
481}
482EXPORT_SYMBOL(idr_remove_all);
483
484/**
485 * idr_destroy - release all cached layers within an idr tree
486 * @idp: idr handle
487 */
488void idr_destroy(struct idr *idp)
489{
490 while (idp->id_free_cnt) {
491 struct idr_layer *p = get_from_free_list(idp);
492 kmem_cache_free(idr_layer_cache, p);
493 }
494}
495EXPORT_SYMBOL(idr_destroy);
496
497/**
498 * idr_find - return pointer for given id
499 * @idp: idr handle
500 * @id: lookup key
501 *
502 * Return the pointer given the id it has been registered with. A %NULL
503 * return indicates that @id is not valid or you passed %NULL in
504 * idr_get_new().
505 *
506 * This function can be called under rcu_read_lock(), given that the leaf
507 * pointers lifetimes are correctly managed.
508 */
509void *idr_find(struct idr *idp, int id)
510{
511 int n;
512 struct idr_layer *p;
513
514 p = rcu_dereference_raw(idp->top);
515 if (!p)
516 return NULL;
517 n = (p->layer+1) * IDR_BITS;
518
519 /* Mask off upper bits we don't use for the search. */
520 id &= MAX_ID_MASK;
521
522 if (id >= (1 << n))
523 return NULL;
524 BUG_ON(n == 0);
525
526 while (n > 0 && p) {
527 n -= IDR_BITS;
528 BUG_ON(n != p->layer*IDR_BITS);
529 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
530 }
531 return((void *)p);
532}
533EXPORT_SYMBOL(idr_find);
534
535/**
536 * idr_for_each - iterate through all stored pointers
537 * @idp: idr handle
538 * @fn: function to be called for each pointer
539 * @data: data passed back to callback function
540 *
541 * Iterate over the pointers registered with the given idr. The
542 * callback function will be called for each pointer currently
543 * registered, passing the id, the pointer and the data pointer passed
544 * to this function. It is not safe to modify the idr tree while in
545 * the callback, so functions such as idr_get_new and idr_remove are
546 * not allowed.
547 *
548 * We check the return of @fn each time. If it returns anything other
549 * than %0, we break out and return that value.
550 *
551 * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove().
552 */
553int idr_for_each(struct idr *idp,
554 int (*fn)(int id, void *p, void *data), void *data)
555{
556 int n, id, max, error = 0;
557 struct idr_layer *p;
558 struct idr_layer *pa[MAX_LEVEL];
559 struct idr_layer **paa = &pa[0];
560
561 n = idp->layers * IDR_BITS;
562 p = rcu_dereference_raw(idp->top);
563 max = 1 << n;
564
565 id = 0;
566 while (id < max) {
567 while (n > 0 && p) {
568 n -= IDR_BITS;
569 *paa++ = p;
570 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
571 }
572
573 if (p) {
574 error = fn(id, (void *)p, data);
575 if (error)
576 break;
577 }
578
579 id += 1 << n;
580 while (n < fls(id)) {
581 n += IDR_BITS;
582 p = *--paa;
583 }
584 }
585
586 return error;
587}
588EXPORT_SYMBOL(idr_for_each);
589
590/**
591 * idr_get_next - lookup next object of id to given id.
592 * @idp: idr handle
593 * @nextidp: pointer to lookup key
594 *
595 * Returns pointer to registered object with id, which is next number to
596 * given id. After being looked up, *@nextidp will be updated for the next
597 * iteration.
598 */
599
600void *idr_get_next(struct idr *idp, int *nextidp)
601{
602 struct idr_layer *p, *pa[MAX_LEVEL];
603 struct idr_layer **paa = &pa[0];
604 int id = *nextidp;
605 int n, max;
606
607 /* find first ent */
608 n = idp->layers * IDR_BITS;
609 max = 1 << n;
610 p = rcu_dereference_raw(idp->top);
611 if (!p)
612 return NULL;
613
614 while (id < max) {
615 while (n > 0 && p) {
616 n -= IDR_BITS;
617 *paa++ = p;
618 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
619 }
620
621 if (p) {
622 *nextidp = id;
623 return p;
624 }
625
626 id += 1 << n;
627 while (n < fls(id)) {
628 n += IDR_BITS;
629 p = *--paa;
630 }
631 }
632 return NULL;
633}
634EXPORT_SYMBOL(idr_get_next);
635
636
637/**
638 * idr_replace - replace pointer for given id
639 * @idp: idr handle
640 * @ptr: pointer you want associated with the id
641 * @id: lookup key
642 *
643 * Replace the pointer registered with an id and return the old value.
644 * A %-ENOENT return indicates that @id was not found.
645 * A %-EINVAL return indicates that @id was not within valid constraints.
646 *
647 * The caller must serialize with writers.
648 */
649void *idr_replace(struct idr *idp, void *ptr, int id)
650{
651 int n;
652 struct idr_layer *p, *old_p;
653
654 p = idp->top;
655 if (!p)
656 return ERR_PTR(-EINVAL);
657
658 n = (p->layer+1) * IDR_BITS;
659
660 id &= MAX_ID_MASK;
661
662 if (id >= (1 << n))
663 return ERR_PTR(-EINVAL);
664
665 n -= IDR_BITS;
666 while ((n > 0) && p) {
667 p = p->ary[(id >> n) & IDR_MASK];
668 n -= IDR_BITS;
669 }
670
671 n = id & IDR_MASK;
672 if (unlikely(p == NULL || !test_bit(n, &p->bitmap)))
673 return ERR_PTR(-ENOENT);
674
675 old_p = p->ary[n];
676 rcu_assign_pointer(p->ary[n], ptr);
677
678 return old_p;
679}
680EXPORT_SYMBOL(idr_replace);
681
682void __init idr_init_cache(void)
683{
684 idr_layer_cache = kmem_cache_create("idr_layer_cache",
685 sizeof(struct idr_layer), 0, SLAB_PANIC, NULL);
686}
687
688/**
689 * idr_init - initialize idr handle
690 * @idp: idr handle
691 *
692 * This function is use to set up the handle (@idp) that you will pass
693 * to the rest of the functions.
694 */
695void idr_init(struct idr *idp)
696{
697 memset(idp, 0, sizeof(struct idr));
698 spin_lock_init(&idp->lock);
699}
700EXPORT_SYMBOL(idr_init);
701
702
703/**
704 * DOC: IDA description
705 * IDA - IDR based ID allocator
706 *
707 * This is id allocator without id -> pointer translation. Memory
708 * usage is much lower than full blown idr because each id only
709 * occupies a bit. ida uses a custom leaf node which contains
710 * IDA_BITMAP_BITS slots.
711 *
712 * 2007-04-25 written by Tejun Heo <htejun@gmail.com>
713 */
714
715static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap)
716{
717 unsigned long flags;
718
719 if (!ida->free_bitmap) {
720 spin_lock_irqsave(&ida->idr.lock, flags);
721 if (!ida->free_bitmap) {
722 ida->free_bitmap = bitmap;
723 bitmap = NULL;
724 }
725 spin_unlock_irqrestore(&ida->idr.lock, flags);
726 }
727
728 kfree(bitmap);
729}
730
731/**
732 * ida_pre_get - reserve resources for ida allocation
733 * @ida: ida handle
734 * @gfp_mask: memory allocation flag
735 *
736 * This function should be called prior to locking and calling the
737 * following function. It preallocates enough memory to satisfy the
738 * worst possible allocation.
739 *
740 * If the system is REALLY out of memory this function returns %0,
741 * otherwise %1.
742 */
743int ida_pre_get(struct ida *ida, gfp_t gfp_mask)
744{
745 /* allocate idr_layers */
746 if (!idr_pre_get(&ida->idr, gfp_mask))
747 return 0;
748
749 /* allocate free_bitmap */
750 if (!ida->free_bitmap) {
751 struct ida_bitmap *bitmap;
752
753 bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask);
754 if (!bitmap)
755 return 0;
756
757 free_bitmap(ida, bitmap);
758 }
759
760 return 1;
761}
762EXPORT_SYMBOL(ida_pre_get);
763
764/**
765 * ida_get_new_above - allocate new ID above or equal to a start id
766 * @ida: ida handle
767 * @starting_id: id to start search at
768 * @p_id: pointer to the allocated handle
769 *
770 * Allocate new ID above or equal to @ida. It should be called with
771 * any required locks.
772 *
773 * If memory is required, it will return %-EAGAIN, you should unlock
774 * and go back to the ida_pre_get() call. If the ida is full, it will
775 * return %-ENOSPC.
776 *
777 * @p_id returns a value in the range @starting_id ... %0x7fffffff.
778 */
779int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
780{
781 struct idr_layer *pa[MAX_LEVEL];
782 struct ida_bitmap *bitmap;
783 unsigned long flags;
784 int idr_id = starting_id / IDA_BITMAP_BITS;
785 int offset = starting_id % IDA_BITMAP_BITS;
786 int t, id;
787
788 restart:
789 /* get vacant slot */
790 t = idr_get_empty_slot(&ida->idr, idr_id, pa);
791 if (t < 0)
792 return _idr_rc_to_errno(t);
793
794 if (t * IDA_BITMAP_BITS >= MAX_ID_BIT)
795 return -ENOSPC;
796
797 if (t != idr_id)
798 offset = 0;
799 idr_id = t;
800
801 /* if bitmap isn't there, create a new one */
802 bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK];
803 if (!bitmap) {
804 spin_lock_irqsave(&ida->idr.lock, flags);
805 bitmap = ida->free_bitmap;
806 ida->free_bitmap = NULL;
807 spin_unlock_irqrestore(&ida->idr.lock, flags);
808
809 if (!bitmap)
810 return -EAGAIN;
811
812 memset(bitmap, 0, sizeof(struct ida_bitmap));
813 rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK],
814 (void *)bitmap);
815 pa[0]->count++;
816 }
817
818 /* lookup for empty slot */
819 t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset);
820 if (t == IDA_BITMAP_BITS) {
821 /* no empty slot after offset, continue to the next chunk */
822 idr_id++;
823 offset = 0;
824 goto restart;
825 }
826
827 id = idr_id * IDA_BITMAP_BITS + t;
828 if (id >= MAX_ID_BIT)
829 return -ENOSPC;
830
831 __set_bit(t, bitmap->bitmap);
832 if (++bitmap->nr_busy == IDA_BITMAP_BITS)
833 idr_mark_full(pa, idr_id);
834
835 *p_id = id;
836
837 /* Each leaf node can handle nearly a thousand slots and the
838 * whole idea of ida is to have small memory foot print.
839 * Throw away extra resources one by one after each successful
840 * allocation.
841 */
842 if (ida->idr.id_free_cnt || ida->free_bitmap) {
843 struct idr_layer *p = get_from_free_list(&ida->idr);
844 if (p)
845 kmem_cache_free(idr_layer_cache, p);
846 }
847
848 return 0;
849}
850EXPORT_SYMBOL(ida_get_new_above);
851
852/**
853 * ida_get_new - allocate new ID
854 * @ida: idr handle
855 * @p_id: pointer to the allocated handle
856 *
857 * Allocate new ID. It should be called with any required locks.
858 *
859 * If memory is required, it will return %-EAGAIN, you should unlock
860 * and go back to the idr_pre_get() call. If the idr is full, it will
861 * return %-ENOSPC.
862 *
863 * @id returns a value in the range %0 ... %0x7fffffff.
864 */
865int ida_get_new(struct ida *ida, int *p_id)
866{
867 return ida_get_new_above(ida, 0, p_id);
868}
869EXPORT_SYMBOL(ida_get_new);
870
871/**
872 * ida_remove - remove the given ID
873 * @ida: ida handle
874 * @id: ID to free
875 */
876void ida_remove(struct ida *ida, int id)
877{
878 struct idr_layer *p = ida->idr.top;
879 int shift = (ida->idr.layers - 1) * IDR_BITS;
880 int idr_id = id / IDA_BITMAP_BITS;
881 int offset = id % IDA_BITMAP_BITS;
882 int n;
883 struct ida_bitmap *bitmap;
884
885 /* clear full bits while looking up the leaf idr_layer */
886 while ((shift > 0) && p) {
887 n = (idr_id >> shift) & IDR_MASK;
888 __clear_bit(n, &p->bitmap);
889 p = p->ary[n];
890 shift -= IDR_BITS;
891 }
892
893 if (p == NULL)
894 goto err;
895
896 n = idr_id & IDR_MASK;
897 __clear_bit(n, &p->bitmap);
898
899 bitmap = (void *)p->ary[n];
900 if (!test_bit(offset, bitmap->bitmap))
901 goto err;
902
903 /* update bitmap and remove it if empty */
904 __clear_bit(offset, bitmap->bitmap);
905 if (--bitmap->nr_busy == 0) {
906 __set_bit(n, &p->bitmap); /* to please idr_remove() */
907 idr_remove(&ida->idr, idr_id);
908 free_bitmap(ida, bitmap);
909 }
910
911 return;
912
913 err:
914 printk(KERN_WARNING
915 "ida_remove called for id=%d which is not allocated.\n", id);
916}
917EXPORT_SYMBOL(ida_remove);
918
919/**
920 * ida_destroy - release all cached layers within an ida tree
921 * @ida: ida handle
922 */
923void ida_destroy(struct ida *ida)
924{
925 idr_destroy(&ida->idr);
926 kfree(ida->free_bitmap);
927}
928EXPORT_SYMBOL(ida_destroy);
929
930/**
931 * ida_simple_get - get a new id.
932 * @ida: the (initialized) ida.
933 * @start: the minimum id (inclusive, < 0x8000000)
934 * @end: the maximum id (exclusive, < 0x8000000 or 0)
935 * @gfp_mask: memory allocation flags
936 *
937 * Allocates an id in the range start <= id < end, or returns -ENOSPC.
938 * On memory allocation failure, returns -ENOMEM.
939 *
940 * Use ida_simple_remove() to get rid of an id.
941 */
942int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
943 gfp_t gfp_mask)
944{
945 int ret, id;
946 unsigned int max;
947
948 BUG_ON((int)start < 0);
949 BUG_ON((int)end < 0);
950
951 if (end == 0)
952 max = 0x80000000;
953 else {
954 BUG_ON(end < start);
955 max = end - 1;
956 }
957
958again:
959 if (!ida_pre_get(ida, gfp_mask))
960 return -ENOMEM;
961
962 spin_lock(&simple_ida_lock);
963 ret = ida_get_new_above(ida, start, &id);
964 if (!ret) {
965 if (id > max) {
966 ida_remove(ida, id);
967 ret = -ENOSPC;
968 } else {
969 ret = id;
970 }
971 }
972 spin_unlock(&simple_ida_lock);
973
974 if (unlikely(ret == -EAGAIN))
975 goto again;
976
977 return ret;
978}
979EXPORT_SYMBOL(ida_simple_get);
980
981/**
982 * ida_simple_remove - remove an allocated id.
983 * @ida: the (initialized) ida.
984 * @id: the id returned by ida_simple_get.
985 */
986void ida_simple_remove(struct ida *ida, unsigned int id)
987{
988 BUG_ON((int)id < 0);
989 spin_lock(&simple_ida_lock);
990 ida_remove(ida, id);
991 spin_unlock(&simple_ida_lock);
992}
993EXPORT_SYMBOL(ida_simple_remove);
994
995/**
996 * ida_init - initialize ida handle
997 * @ida: ida handle
998 *
999 * This function is use to set up the handle (@ida) that you will pass
1000 * to the rest of the functions.
1001 */
1002void ida_init(struct ida *ida)
1003{
1004 memset(ida, 0, sizeof(struct ida));
1005 idr_init(&ida->idr);
1006
1007}
1008EXPORT_SYMBOL(ida_init);