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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 | * 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 | |
38 | static struct kmem_cache *idr_layer_cache; |
39 | |
40 | static struct idr_layer *get_from_free_list(struct idr *idp) |
41 | { |
42 | struct idr_layer *p; |
43 | unsigned long flags; |
44 | |
45 | spin_lock_irqsave(&idp->lock, flags); |
46 | if ((p = idp->id_free)) { |
47 | idp->id_free = p->ary[0]; |
48 | idp->id_free_cnt--; |
49 | p->ary[0] = NULL; |
50 | } |
51 | spin_unlock_irqrestore(&idp->lock, flags); |
52 | return(p); |
53 | } |
54 | |
55 | static void idr_layer_rcu_free(struct rcu_head *head) |
56 | { |
57 | struct idr_layer *layer; |
58 | |
59 | layer = container_of(head, struct idr_layer, rcu_head); |
60 | kmem_cache_free(idr_layer_cache, layer); |
61 | } |
62 | |
63 | static inline void free_layer(struct idr_layer *p) |
64 | { |
65 | call_rcu(&p->rcu_head, idr_layer_rcu_free); |
66 | } |
67 | |
68 | /* only called when idp->lock is held */ |
69 | static void __move_to_free_list(struct idr *idp, struct idr_layer *p) |
70 | { |
71 | p->ary[0] = idp->id_free; |
72 | idp->id_free = p; |
73 | idp->id_free_cnt++; |
74 | } |
75 | |
76 | static void move_to_free_list(struct idr *idp, struct idr_layer *p) |
77 | { |
78 | unsigned long flags; |
79 | |
80 | /* |
81 | * Depends on the return element being zeroed. |
82 | */ |
83 | spin_lock_irqsave(&idp->lock, flags); |
84 | __move_to_free_list(idp, p); |
85 | spin_unlock_irqrestore(&idp->lock, flags); |
86 | } |
87 | |
88 | static void idr_mark_full(struct idr_layer **pa, int id) |
89 | { |
90 | struct idr_layer *p = pa[0]; |
91 | int l = 0; |
92 | |
93 | __set_bit(id & IDR_MASK, &p->bitmap); |
94 | /* |
95 | * If this layer is full mark the bit in the layer above to |
96 | * show that this part of the radix tree is full. This may |
97 | * complete the layer above and require walking up the radix |
98 | * tree. |
99 | */ |
100 | while (p->bitmap == IDR_FULL) { |
101 | if (!(p = pa[++l])) |
102 | break; |
103 | id = id >> IDR_BITS; |
104 | __set_bit((id & IDR_MASK), &p->bitmap); |
105 | } |
106 | } |
107 | |
108 | /** |
109 | * idr_pre_get - reserver resources for idr allocation |
110 | * @idp: idr handle |
111 | * @gfp_mask: memory allocation flags |
112 | * |
113 | * This function should be called prior to locking and calling the |
114 | * idr_get_new* functions. It preallocates enough memory to satisfy |
115 | * the worst possible allocation. |
116 | * |
117 | * If the system is REALLY out of memory this function returns 0, |
118 | * otherwise 1. |
119 | */ |
120 | int idr_pre_get(struct idr *idp, gfp_t gfp_mask) |
121 | { |
122 | while (idp->id_free_cnt < IDR_FREE_MAX) { |
123 | struct idr_layer *new; |
124 | new = kmem_cache_zalloc(idr_layer_cache, gfp_mask); |
125 | if (new == NULL) |
126 | return (0); |
127 | move_to_free_list(idp, new); |
128 | } |
129 | return 1; |
130 | } |
131 | EXPORT_SYMBOL(idr_pre_get); |
132 | |
133 | static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa) |
134 | { |
135 | int n, m, sh; |
136 | struct idr_layer *p, *new; |
137 | int l, id, oid; |
138 | unsigned long bm; |
139 | |
140 | id = *starting_id; |
141 | restart: |
142 | p = idp->top; |
143 | l = idp->layers; |
144 | pa[l--] = NULL; |
145 | while (1) { |
146 | /* |
147 | * We run around this while until we reach the leaf node... |
148 | */ |
149 | n = (id >> (IDR_BITS*l)) & IDR_MASK; |
150 | bm = ~p->bitmap; |
151 | m = find_next_bit(&bm, IDR_SIZE, n); |
152 | if (m == IDR_SIZE) { |
153 | /* no space available go back to previous layer. */ |
154 | l++; |
155 | oid = id; |
156 | id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1; |
157 | |
158 | /* if already at the top layer, we need to grow */ |
159 | if (id >= 1 << (idp->layers * IDR_BITS)) { |
160 | *starting_id = id; |
161 | return IDR_NEED_TO_GROW; |
162 | } |
163 | p = pa[l]; |
164 | BUG_ON(!p); |
165 | |
166 | /* If we need to go up one layer, continue the |
167 | * loop; otherwise, restart from the top. |
168 | */ |
169 | sh = IDR_BITS * (l + 1); |
170 | if (oid >> sh == id >> sh) |
171 | continue; |
172 | else |
173 | goto restart; |
174 | } |
175 | if (m != n) { |
176 | sh = IDR_BITS*l; |
177 | id = ((id >> sh) ^ n ^ m) << sh; |
178 | } |
179 | if ((id >= MAX_ID_BIT) || (id < 0)) |
180 | return IDR_NOMORE_SPACE; |
181 | if (l == 0) |
182 | break; |
183 | /* |
184 | * Create the layer below if it is missing. |
185 | */ |
186 | if (!p->ary[m]) { |
187 | new = get_from_free_list(idp); |
188 | if (!new) |
189 | return -1; |
190 | new->layer = l-1; |
191 | rcu_assign_pointer(p->ary[m], new); |
192 | p->count++; |
193 | } |
194 | pa[l--] = p; |
195 | p = p->ary[m]; |
196 | } |
197 | |
198 | pa[l] = p; |
199 | return id; |
200 | } |
201 | |
202 | static int idr_get_empty_slot(struct idr *idp, int starting_id, |
203 | struct idr_layer **pa) |
204 | { |
205 | struct idr_layer *p, *new; |
206 | int layers, v, id; |
207 | unsigned long flags; |
208 | |
209 | id = starting_id; |
210 | build_up: |
211 | p = idp->top; |
212 | layers = idp->layers; |
213 | if (unlikely(!p)) { |
214 | if (!(p = get_from_free_list(idp))) |
215 | return -1; |
216 | p->layer = 0; |
217 | layers = 1; |
218 | } |
219 | /* |
220 | * Add a new layer to the top of the tree if the requested |
221 | * id is larger than the currently allocated space. |
222 | */ |
223 | while ((layers < (MAX_LEVEL - 1)) && (id >= (1 << (layers*IDR_BITS)))) { |
224 | layers++; |
225 | if (!p->count) { |
226 | /* special case: if the tree is currently empty, |
227 | * then we grow the tree by moving the top node |
228 | * upwards. |
229 | */ |
230 | p->layer++; |
231 | continue; |
232 | } |
233 | if (!(new = get_from_free_list(idp))) { |
234 | /* |
235 | * The allocation failed. If we built part of |
236 | * the structure tear it down. |
237 | */ |
238 | spin_lock_irqsave(&idp->lock, flags); |
239 | for (new = p; p && p != idp->top; new = p) { |
240 | p = p->ary[0]; |
241 | new->ary[0] = NULL; |
242 | new->bitmap = new->count = 0; |
243 | __move_to_free_list(idp, new); |
244 | } |
245 | spin_unlock_irqrestore(&idp->lock, flags); |
246 | return -1; |
247 | } |
248 | new->ary[0] = p; |
249 | new->count = 1; |
250 | new->layer = layers-1; |
251 | if (p->bitmap == IDR_FULL) |
252 | __set_bit(0, &new->bitmap); |
253 | p = new; |
254 | } |
255 | rcu_assign_pointer(idp->top, p); |
256 | idp->layers = layers; |
257 | v = sub_alloc(idp, &id, pa); |
258 | if (v == IDR_NEED_TO_GROW) |
259 | goto build_up; |
260 | return(v); |
261 | } |
262 | |
263 | static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id) |
264 | { |
265 | struct idr_layer *pa[MAX_LEVEL]; |
266 | int id; |
267 | |
268 | id = idr_get_empty_slot(idp, starting_id, pa); |
269 | if (id >= 0) { |
270 | /* |
271 | * Successfully found an empty slot. Install the user |
272 | * pointer and mark the slot full. |
273 | */ |
274 | rcu_assign_pointer(pa[0]->ary[id & IDR_MASK], |
275 | (struct idr_layer *)ptr); |
276 | pa[0]->count++; |
277 | idr_mark_full(pa, id); |
278 | } |
279 | |
280 | return id; |
281 | } |
282 | |
283 | /** |
284 | * idr_get_new_above - allocate new idr entry above or equal to a start id |
285 | * @idp: idr handle |
286 | * @ptr: pointer you want associated with the id |
287 | * @start_id: id to start search at |
288 | * @id: pointer to the allocated handle |
289 | * |
290 | * This is the allocate id function. It should be called with any |
291 | * required locks. |
292 | * |
293 | * If memory is required, it will return -EAGAIN, you should unlock |
294 | * and go back to the idr_pre_get() call. If the idr is full, it will |
295 | * return -ENOSPC. |
296 | * |
297 | * @id returns a value in the range @starting_id ... 0x7fffffff |
298 | */ |
299 | int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id) |
300 | { |
301 | int rv; |
302 | |
303 | rv = idr_get_new_above_int(idp, ptr, starting_id); |
304 | /* |
305 | * This is a cheap hack until the IDR code can be fixed to |
306 | * return proper error values. |
307 | */ |
308 | if (rv < 0) |
309 | return _idr_rc_to_errno(rv); |
310 | *id = rv; |
311 | return 0; |
312 | } |
313 | EXPORT_SYMBOL(idr_get_new_above); |
314 | |
315 | /** |
316 | * idr_get_new - allocate new idr entry |
317 | * @idp: idr handle |
318 | * @ptr: pointer you want associated with the id |
319 | * @id: pointer to the allocated handle |
320 | * |
321 | * This is the allocate id function. It should be called with any |
322 | * required locks. |
323 | * |
324 | * If memory is required, it will return -EAGAIN, you should unlock |
325 | * and go back to the idr_pre_get() call. If the idr is full, it will |
326 | * return -ENOSPC. |
327 | * |
328 | * @id returns a value in the range 0 ... 0x7fffffff |
329 | */ |
330 | int idr_get_new(struct idr *idp, void *ptr, int *id) |
331 | { |
332 | int rv; |
333 | |
334 | rv = idr_get_new_above_int(idp, ptr, 0); |
335 | /* |
336 | * This is a cheap hack until the IDR code can be fixed to |
337 | * return proper error values. |
338 | */ |
339 | if (rv < 0) |
340 | return _idr_rc_to_errno(rv); |
341 | *id = rv; |
342 | return 0; |
343 | } |
344 | EXPORT_SYMBOL(idr_get_new); |
345 | |
346 | static void idr_remove_warning(int id) |
347 | { |
348 | printk(KERN_WARNING |
349 | "idr_remove called for id=%d which is not allocated.\n", id); |
350 | dump_stack(); |
351 | } |
352 | |
353 | static void sub_remove(struct idr *idp, int shift, int id) |
354 | { |
355 | struct idr_layer *p = idp->top; |
356 | struct idr_layer **pa[MAX_LEVEL]; |
357 | struct idr_layer ***paa = &pa[0]; |
358 | struct idr_layer *to_free; |
359 | int n; |
360 | |
361 | *paa = NULL; |
362 | *++paa = &idp->top; |
363 | |
364 | while ((shift > 0) && p) { |
365 | n = (id >> shift) & IDR_MASK; |
366 | __clear_bit(n, &p->bitmap); |
367 | *++paa = &p->ary[n]; |
368 | p = p->ary[n]; |
369 | shift -= IDR_BITS; |
370 | } |
371 | n = id & IDR_MASK; |
372 | if (likely(p != NULL && test_bit(n, &p->bitmap))){ |
373 | __clear_bit(n, &p->bitmap); |
374 | rcu_assign_pointer(p->ary[n], NULL); |
375 | to_free = NULL; |
376 | while(*paa && ! --((**paa)->count)){ |
377 | if (to_free) |
378 | free_layer(to_free); |
379 | to_free = **paa; |
380 | **paa-- = NULL; |
381 | } |
382 | if (!*paa) |
383 | idp->layers = 0; |
384 | if (to_free) |
385 | free_layer(to_free); |
386 | } else |
387 | idr_remove_warning(id); |
388 | } |
389 | |
390 | /** |
391 | * idr_remove - remove the given id and free it's slot |
392 | * @idp: idr handle |
393 | * @id: unique key |
394 | */ |
395 | void idr_remove(struct idr *idp, int id) |
396 | { |
397 | struct idr_layer *p; |
398 | struct idr_layer *to_free; |
399 | |
400 | /* Mask off upper bits we don't use for the search. */ |
401 | id &= MAX_ID_MASK; |
402 | |
403 | sub_remove(idp, (idp->layers - 1) * IDR_BITS, id); |
404 | if (idp->top && idp->top->count == 1 && (idp->layers > 1) && |
405 | idp->top->ary[0]) { |
406 | /* |
407 | * Single child at leftmost slot: we can shrink the tree. |
408 | * This level is not needed anymore since when layers are |
409 | * inserted, they are inserted at the top of the existing |
410 | * tree. |
411 | */ |
412 | to_free = idp->top; |
413 | p = idp->top->ary[0]; |
414 | rcu_assign_pointer(idp->top, p); |
415 | --idp->layers; |
416 | to_free->bitmap = to_free->count = 0; |
417 | free_layer(to_free); |
418 | } |
419 | while (idp->id_free_cnt >= IDR_FREE_MAX) { |
420 | p = get_from_free_list(idp); |
421 | /* |
422 | * Note: we don't call the rcu callback here, since the only |
423 | * layers that fall into the freelist are those that have been |
424 | * preallocated. |
425 | */ |
426 | kmem_cache_free(idr_layer_cache, p); |
427 | } |
428 | return; |
429 | } |
430 | EXPORT_SYMBOL(idr_remove); |
431 | |
432 | /** |
433 | * idr_remove_all - remove all ids from the given idr tree |
434 | * @idp: idr handle |
435 | * |
436 | * idr_destroy() only frees up unused, cached idp_layers, but this |
437 | * function will remove all id mappings and leave all idp_layers |
438 | * unused. |
439 | * |
440 | * A typical clean-up sequence for objects stored in an idr tree, will |
441 | * use idr_for_each() to free all objects, if necessay, then |
442 | * idr_remove_all() to remove all ids, and idr_destroy() to free |
443 | * up the cached idr_layers. |
444 | */ |
445 | void idr_remove_all(struct idr *idp) |
446 | { |
447 | int n, id, max; |
448 | int bt_mask; |
449 | struct idr_layer *p; |
450 | struct idr_layer *pa[MAX_LEVEL]; |
451 | struct idr_layer **paa = &pa[0]; |
452 | |
453 | n = idp->layers * IDR_BITS; |
454 | p = idp->top; |
455 | rcu_assign_pointer(idp->top, NULL); |
456 | max = 1 << n; |
457 | |
458 | id = 0; |
459 | while (id < max) { |
460 | while (n > IDR_BITS && p) { |
461 | n -= IDR_BITS; |
462 | *paa++ = p; |
463 | p = p->ary[(id >> n) & IDR_MASK]; |
464 | } |
465 | |
466 | bt_mask = id; |
467 | id += 1 << n; |
468 | /* Get the highest bit that the above add changed from 0->1. */ |
469 | while (n < fls(id ^ bt_mask)) { |
470 | if (p) |
471 | free_layer(p); |
472 | n += IDR_BITS; |
473 | p = *--paa; |
474 | } |
475 | } |
476 | idp->layers = 0; |
477 | } |
478 | EXPORT_SYMBOL(idr_remove_all); |
479 | |
480 | /** |
481 | * idr_destroy - release all cached layers within an idr tree |
482 | * idp: idr handle |
483 | */ |
484 | void idr_destroy(struct idr *idp) |
485 | { |
486 | while (idp->id_free_cnt) { |
487 | struct idr_layer *p = get_from_free_list(idp); |
488 | kmem_cache_free(idr_layer_cache, p); |
489 | } |
490 | } |
491 | EXPORT_SYMBOL(idr_destroy); |
492 | |
493 | /** |
494 | * idr_find - return pointer for given id |
495 | * @idp: idr handle |
496 | * @id: lookup key |
497 | * |
498 | * Return the pointer given the id it has been registered with. A %NULL |
499 | * return indicates that @id is not valid or you passed %NULL in |
500 | * idr_get_new(). |
501 | * |
502 | * This function can be called under rcu_read_lock(), given that the leaf |
503 | * pointers lifetimes are correctly managed. |
504 | */ |
505 | void *idr_find(struct idr *idp, int id) |
506 | { |
507 | int n; |
508 | struct idr_layer *p; |
509 | |
510 | p = rcu_dereference_raw(idp->top); |
511 | if (!p) |
512 | return NULL; |
513 | n = (p->layer+1) * IDR_BITS; |
514 | |
515 | /* Mask off upper bits we don't use for the search. */ |
516 | id &= MAX_ID_MASK; |
517 | |
518 | if (id >= (1 << n)) |
519 | return NULL; |
520 | BUG_ON(n == 0); |
521 | |
522 | while (n > 0 && p) { |
523 | n -= IDR_BITS; |
524 | BUG_ON(n != p->layer*IDR_BITS); |
525 | p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]); |
526 | } |
527 | return((void *)p); |
528 | } |
529 | EXPORT_SYMBOL(idr_find); |
530 | |
531 | /** |
532 | * idr_for_each - iterate through all stored pointers |
533 | * @idp: idr handle |
534 | * @fn: function to be called for each pointer |
535 | * @data: data passed back to callback function |
536 | * |
537 | * Iterate over the pointers registered with the given idr. The |
538 | * callback function will be called for each pointer currently |
539 | * registered, passing the id, the pointer and the data pointer passed |
540 | * to this function. It is not safe to modify the idr tree while in |
541 | * the callback, so functions such as idr_get_new and idr_remove are |
542 | * not allowed. |
543 | * |
544 | * We check the return of @fn each time. If it returns anything other |
545 | * than 0, we break out and return that value. |
546 | * |
547 | * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove(). |
548 | */ |
549 | int idr_for_each(struct idr *idp, |
550 | int (*fn)(int id, void *p, void *data), void *data) |
551 | { |
552 | int n, id, max, error = 0; |
553 | struct idr_layer *p; |
554 | struct idr_layer *pa[MAX_LEVEL]; |
555 | struct idr_layer **paa = &pa[0]; |
556 | |
557 | n = idp->layers * IDR_BITS; |
558 | p = rcu_dereference_raw(idp->top); |
559 | max = 1 << n; |
560 | |
561 | id = 0; |
562 | while (id < max) { |
563 | while (n > 0 && p) { |
564 | n -= IDR_BITS; |
565 | *paa++ = p; |
566 | p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]); |
567 | } |
568 | |
569 | if (p) { |
570 | error = fn(id, (void *)p, data); |
571 | if (error) |
572 | break; |
573 | } |
574 | |
575 | id += 1 << n; |
576 | while (n < fls(id)) { |
577 | n += IDR_BITS; |
578 | p = *--paa; |
579 | } |
580 | } |
581 | |
582 | return error; |
583 | } |
584 | EXPORT_SYMBOL(idr_for_each); |
585 | |
586 | /** |
587 | * idr_get_next - lookup next object of id to given id. |
588 | * @idp: idr handle |
589 | * @id: pointer to lookup key |
590 | * |
591 | * Returns pointer to registered object with id, which is next number to |
592 | * given id. |
593 | */ |
594 | |
595 | void *idr_get_next(struct idr *idp, int *nextidp) |
596 | { |
597 | struct idr_layer *p, *pa[MAX_LEVEL]; |
598 | struct idr_layer **paa = &pa[0]; |
599 | int id = *nextidp; |
600 | int n, max; |
601 | |
602 | /* find first ent */ |
603 | n = idp->layers * IDR_BITS; |
604 | max = 1 << n; |
605 | p = rcu_dereference_raw(idp->top); |
606 | if (!p) |
607 | return NULL; |
608 | |
609 | while (id < max) { |
610 | while (n > 0 && p) { |
611 | n -= IDR_BITS; |
612 | *paa++ = p; |
613 | p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]); |
614 | } |
615 | |
616 | if (p) { |
617 | *nextidp = id; |
618 | return p; |
619 | } |
620 | |
621 | id += 1 << n; |
622 | while (n < fls(id)) { |
623 | n += IDR_BITS; |
624 | p = *--paa; |
625 | } |
626 | } |
627 | return NULL; |
628 | } |
629 | EXPORT_SYMBOL(idr_get_next); |
630 | |
631 | |
632 | /** |
633 | * idr_replace - replace pointer for given id |
634 | * @idp: idr handle |
635 | * @ptr: pointer you want associated with the id |
636 | * @id: lookup key |
637 | * |
638 | * Replace the pointer registered with an id and return the old value. |
639 | * A -ENOENT return indicates that @id was not found. |
640 | * A -EINVAL return indicates that @id was not within valid constraints. |
641 | * |
642 | * The caller must serialize with writers. |
643 | */ |
644 | void *idr_replace(struct idr *idp, void *ptr, int id) |
645 | { |
646 | int n; |
647 | struct idr_layer *p, *old_p; |
648 | |
649 | p = idp->top; |
650 | if (!p) |
651 | return ERR_PTR(-EINVAL); |
652 | |
653 | n = (p->layer+1) * IDR_BITS; |
654 | |
655 | id &= MAX_ID_MASK; |
656 | |
657 | if (id >= (1 << n)) |
658 | return ERR_PTR(-EINVAL); |
659 | |
660 | n -= IDR_BITS; |
661 | while ((n > 0) && p) { |
662 | p = p->ary[(id >> n) & IDR_MASK]; |
663 | n -= IDR_BITS; |
664 | } |
665 | |
666 | n = id & IDR_MASK; |
667 | if (unlikely(p == NULL || !test_bit(n, &p->bitmap))) |
668 | return ERR_PTR(-ENOENT); |
669 | |
670 | old_p = p->ary[n]; |
671 | rcu_assign_pointer(p->ary[n], ptr); |
672 | |
673 | return old_p; |
674 | } |
675 | EXPORT_SYMBOL(idr_replace); |
676 | |
677 | void __init idr_init_cache(void) |
678 | { |
679 | idr_layer_cache = kmem_cache_create("idr_layer_cache", |
680 | sizeof(struct idr_layer), 0, SLAB_PANIC, NULL); |
681 | } |
682 | |
683 | /** |
684 | * idr_init - initialize idr handle |
685 | * @idp: idr handle |
686 | * |
687 | * This function is use to set up the handle (@idp) that you will pass |
688 | * to the rest of the functions. |
689 | */ |
690 | void idr_init(struct idr *idp) |
691 | { |
692 | memset(idp, 0, sizeof(struct idr)); |
693 | spin_lock_init(&idp->lock); |
694 | } |
695 | EXPORT_SYMBOL(idr_init); |
696 | |
697 | |
698 | /* |
699 | * IDA - IDR based ID allocator |
700 | * |
701 | * this is id allocator without id -> pointer translation. Memory |
702 | * usage is much lower than full blown idr because each id only |
703 | * occupies a bit. ida uses a custom leaf node which contains |
704 | * IDA_BITMAP_BITS slots. |
705 | * |
706 | * 2007-04-25 written by Tejun Heo <htejun@gmail.com> |
707 | */ |
708 | |
709 | static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap) |
710 | { |
711 | unsigned long flags; |
712 | |
713 | if (!ida->free_bitmap) { |
714 | spin_lock_irqsave(&ida->idr.lock, flags); |
715 | if (!ida->free_bitmap) { |
716 | ida->free_bitmap = bitmap; |
717 | bitmap = NULL; |
718 | } |
719 | spin_unlock_irqrestore(&ida->idr.lock, flags); |
720 | } |
721 | |
722 | kfree(bitmap); |
723 | } |
724 | |
725 | /** |
726 | * ida_pre_get - reserve resources for ida allocation |
727 | * @ida: ida handle |
728 | * @gfp_mask: memory allocation flag |
729 | * |
730 | * This function should be called prior to locking and calling the |
731 | * following function. It preallocates enough memory to satisfy the |
732 | * worst possible allocation. |
733 | * |
734 | * If the system is REALLY out of memory this function returns 0, |
735 | * otherwise 1. |
736 | */ |
737 | int ida_pre_get(struct ida *ida, gfp_t gfp_mask) |
738 | { |
739 | /* allocate idr_layers */ |
740 | if (!idr_pre_get(&ida->idr, gfp_mask)) |
741 | return 0; |
742 | |
743 | /* allocate free_bitmap */ |
744 | if (!ida->free_bitmap) { |
745 | struct ida_bitmap *bitmap; |
746 | |
747 | bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask); |
748 | if (!bitmap) |
749 | return 0; |
750 | |
751 | free_bitmap(ida, bitmap); |
752 | } |
753 | |
754 | return 1; |
755 | } |
756 | EXPORT_SYMBOL(ida_pre_get); |
757 | |
758 | /** |
759 | * ida_get_new_above - allocate new ID above or equal to a start id |
760 | * @ida: ida handle |
761 | * @staring_id: id to start search at |
762 | * @p_id: pointer to the allocated handle |
763 | * |
764 | * Allocate new ID above or equal to @ida. It should be called with |
765 | * any required locks. |
766 | * |
767 | * If memory is required, it will return -EAGAIN, you should unlock |
768 | * and go back to the ida_pre_get() call. If the ida is full, it will |
769 | * return -ENOSPC. |
770 | * |
771 | * @p_id returns a value in the range @starting_id ... 0x7fffffff. |
772 | */ |
773 | int ida_get_new_above(struct ida *ida, int starting_id, int *p_id) |
774 | { |
775 | struct idr_layer *pa[MAX_LEVEL]; |
776 | struct ida_bitmap *bitmap; |
777 | unsigned long flags; |
778 | int idr_id = starting_id / IDA_BITMAP_BITS; |
779 | int offset = starting_id % IDA_BITMAP_BITS; |
780 | int t, id; |
781 | |
782 | restart: |
783 | /* get vacant slot */ |
784 | t = idr_get_empty_slot(&ida->idr, idr_id, pa); |
785 | if (t < 0) |
786 | return _idr_rc_to_errno(t); |
787 | |
788 | if (t * IDA_BITMAP_BITS >= MAX_ID_BIT) |
789 | return -ENOSPC; |
790 | |
791 | if (t != idr_id) |
792 | offset = 0; |
793 | idr_id = t; |
794 | |
795 | /* if bitmap isn't there, create a new one */ |
796 | bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK]; |
797 | if (!bitmap) { |
798 | spin_lock_irqsave(&ida->idr.lock, flags); |
799 | bitmap = ida->free_bitmap; |
800 | ida->free_bitmap = NULL; |
801 | spin_unlock_irqrestore(&ida->idr.lock, flags); |
802 | |
803 | if (!bitmap) |
804 | return -EAGAIN; |
805 | |
806 | memset(bitmap, 0, sizeof(struct ida_bitmap)); |
807 | rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK], |
808 | (void *)bitmap); |
809 | pa[0]->count++; |
810 | } |
811 | |
812 | /* lookup for empty slot */ |
813 | t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset); |
814 | if (t == IDA_BITMAP_BITS) { |
815 | /* no empty slot after offset, continue to the next chunk */ |
816 | idr_id++; |
817 | offset = 0; |
818 | goto restart; |
819 | } |
820 | |
821 | id = idr_id * IDA_BITMAP_BITS + t; |
822 | if (id >= MAX_ID_BIT) |
823 | return -ENOSPC; |
824 | |
825 | __set_bit(t, bitmap->bitmap); |
826 | if (++bitmap->nr_busy == IDA_BITMAP_BITS) |
827 | idr_mark_full(pa, idr_id); |
828 | |
829 | *p_id = id; |
830 | |
831 | /* Each leaf node can handle nearly a thousand slots and the |
832 | * whole idea of ida is to have small memory foot print. |
833 | * Throw away extra resources one by one after each successful |
834 | * allocation. |
835 | */ |
836 | if (ida->idr.id_free_cnt || ida->free_bitmap) { |
837 | struct idr_layer *p = get_from_free_list(&ida->idr); |
838 | if (p) |
839 | kmem_cache_free(idr_layer_cache, p); |
840 | } |
841 | |
842 | return 0; |
843 | } |
844 | EXPORT_SYMBOL(ida_get_new_above); |
845 | |
846 | /** |
847 | * ida_get_new - allocate new ID |
848 | * @ida: idr handle |
849 | * @p_id: pointer to the allocated handle |
850 | * |
851 | * Allocate new ID. It should be called with any required locks. |
852 | * |
853 | * If memory is required, it will return -EAGAIN, you should unlock |
854 | * and go back to the idr_pre_get() call. If the idr is full, it will |
855 | * return -ENOSPC. |
856 | * |
857 | * @id returns a value in the range 0 ... 0x7fffffff. |
858 | */ |
859 | int ida_get_new(struct ida *ida, int *p_id) |
860 | { |
861 | return ida_get_new_above(ida, 0, p_id); |
862 | } |
863 | EXPORT_SYMBOL(ida_get_new); |
864 | |
865 | /** |
866 | * ida_remove - remove the given ID |
867 | * @ida: ida handle |
868 | * @id: ID to free |
869 | */ |
870 | void ida_remove(struct ida *ida, int id) |
871 | { |
872 | struct idr_layer *p = ida->idr.top; |
873 | int shift = (ida->idr.layers - 1) * IDR_BITS; |
874 | int idr_id = id / IDA_BITMAP_BITS; |
875 | int offset = id % IDA_BITMAP_BITS; |
876 | int n; |
877 | struct ida_bitmap *bitmap; |
878 | |
879 | /* clear full bits while looking up the leaf idr_layer */ |
880 | while ((shift > 0) && p) { |
881 | n = (idr_id >> shift) & IDR_MASK; |
882 | __clear_bit(n, &p->bitmap); |
883 | p = p->ary[n]; |
884 | shift -= IDR_BITS; |
885 | } |
886 | |
887 | if (p == NULL) |
888 | goto err; |
889 | |
890 | n = idr_id & IDR_MASK; |
891 | __clear_bit(n, &p->bitmap); |
892 | |
893 | bitmap = (void *)p->ary[n]; |
894 | if (!test_bit(offset, bitmap->bitmap)) |
895 | goto err; |
896 | |
897 | /* update bitmap and remove it if empty */ |
898 | __clear_bit(offset, bitmap->bitmap); |
899 | if (--bitmap->nr_busy == 0) { |
900 | __set_bit(n, &p->bitmap); /* to please idr_remove() */ |
901 | idr_remove(&ida->idr, idr_id); |
902 | free_bitmap(ida, bitmap); |
903 | } |
904 | |
905 | return; |
906 | |
907 | err: |
908 | printk(KERN_WARNING |
909 | "ida_remove called for id=%d which is not allocated.\n", id); |
910 | } |
911 | EXPORT_SYMBOL(ida_remove); |
912 | |
913 | /** |
914 | * ida_destroy - release all cached layers within an ida tree |
915 | * ida: ida handle |
916 | */ |
917 | void ida_destroy(struct ida *ida) |
918 | { |
919 | idr_destroy(&ida->idr); |
920 | kfree(ida->free_bitmap); |
921 | } |
922 | EXPORT_SYMBOL(ida_destroy); |
923 | |
924 | /** |
925 | * ida_init - initialize ida handle |
926 | * @ida: ida handle |
927 | * |
928 | * This function is use to set up the handle (@ida) that you will pass |
929 | * to the rest of the functions. |
930 | */ |
931 | void ida_init(struct ida *ida) |
932 | { |
933 | memset(ida, 0, sizeof(struct ida)); |
934 | idr_init(&ida->idr); |
935 | |
936 | } |
937 | EXPORT_SYMBOL(ida_init); |
938 |
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