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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 ide |
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 ide |
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 | struct idr_layer *p; |
449 | struct idr_layer *pa[MAX_LEVEL]; |
450 | struct idr_layer **paa = &pa[0]; |
451 | |
452 | n = idp->layers * IDR_BITS; |
453 | p = idp->top; |
454 | rcu_assign_pointer(idp->top, NULL); |
455 | max = 1 << n; |
456 | |
457 | id = 0; |
458 | while (id < max) { |
459 | while (n > IDR_BITS && p) { |
460 | n -= IDR_BITS; |
461 | *paa++ = p; |
462 | p = p->ary[(id >> n) & IDR_MASK]; |
463 | } |
464 | |
465 | id += 1 << n; |
466 | while (n < fls(id)) { |
467 | if (p) |
468 | free_layer(p); |
469 | n += IDR_BITS; |
470 | p = *--paa; |
471 | } |
472 | } |
473 | idp->layers = 0; |
474 | } |
475 | EXPORT_SYMBOL(idr_remove_all); |
476 | |
477 | /** |
478 | * idr_destroy - release all cached layers within an idr tree |
479 | * idp: idr handle |
480 | */ |
481 | void idr_destroy(struct idr *idp) |
482 | { |
483 | while (idp->id_free_cnt) { |
484 | struct idr_layer *p = get_from_free_list(idp); |
485 | kmem_cache_free(idr_layer_cache, p); |
486 | } |
487 | } |
488 | EXPORT_SYMBOL(idr_destroy); |
489 | |
490 | /** |
491 | * idr_find - return pointer for given id |
492 | * @idp: idr handle |
493 | * @id: lookup key |
494 | * |
495 | * Return the pointer given the id it has been registered with. A %NULL |
496 | * return indicates that @id is not valid or you passed %NULL in |
497 | * idr_get_new(). |
498 | * |
499 | * This function can be called under rcu_read_lock(), given that the leaf |
500 | * pointers lifetimes are correctly managed. |
501 | */ |
502 | void *idr_find(struct idr *idp, int id) |
503 | { |
504 | int n; |
505 | struct idr_layer *p; |
506 | |
507 | p = rcu_dereference(idp->top); |
508 | if (!p) |
509 | return NULL; |
510 | n = (p->layer+1) * IDR_BITS; |
511 | |
512 | /* Mask off upper bits we don't use for the search. */ |
513 | id &= MAX_ID_MASK; |
514 | |
515 | if (id >= (1 << n)) |
516 | return NULL; |
517 | BUG_ON(n == 0); |
518 | |
519 | while (n > 0 && p) { |
520 | n -= IDR_BITS; |
521 | BUG_ON(n != p->layer*IDR_BITS); |
522 | p = rcu_dereference(p->ary[(id >> n) & IDR_MASK]); |
523 | } |
524 | return((void *)p); |
525 | } |
526 | EXPORT_SYMBOL(idr_find); |
527 | |
528 | /** |
529 | * idr_for_each - iterate through all stored pointers |
530 | * @idp: idr handle |
531 | * @fn: function to be called for each pointer |
532 | * @data: data passed back to callback function |
533 | * |
534 | * Iterate over the pointers registered with the given idr. The |
535 | * callback function will be called for each pointer currently |
536 | * registered, passing the id, the pointer and the data pointer passed |
537 | * to this function. It is not safe to modify the idr tree while in |
538 | * the callback, so functions such as idr_get_new and idr_remove are |
539 | * not allowed. |
540 | * |
541 | * We check the return of @fn each time. If it returns anything other |
542 | * than 0, we break out and return that value. |
543 | * |
544 | * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove(). |
545 | */ |
546 | int idr_for_each(struct idr *idp, |
547 | int (*fn)(int id, void *p, void *data), void *data) |
548 | { |
549 | int n, id, max, error = 0; |
550 | struct idr_layer *p; |
551 | struct idr_layer *pa[MAX_LEVEL]; |
552 | struct idr_layer **paa = &pa[0]; |
553 | |
554 | n = idp->layers * IDR_BITS; |
555 | p = rcu_dereference(idp->top); |
556 | max = 1 << n; |
557 | |
558 | id = 0; |
559 | while (id < max) { |
560 | while (n > 0 && p) { |
561 | n -= IDR_BITS; |
562 | *paa++ = p; |
563 | p = rcu_dereference(p->ary[(id >> n) & IDR_MASK]); |
564 | } |
565 | |
566 | if (p) { |
567 | error = fn(id, (void *)p, data); |
568 | if (error) |
569 | break; |
570 | } |
571 | |
572 | id += 1 << n; |
573 | while (n < fls(id)) { |
574 | n += IDR_BITS; |
575 | p = *--paa; |
576 | } |
577 | } |
578 | |
579 | return error; |
580 | } |
581 | EXPORT_SYMBOL(idr_for_each); |
582 | |
583 | /** |
584 | * idr_get_next - lookup next object of id to given id. |
585 | * @idp: idr handle |
586 | * @id: pointer to lookup key |
587 | * |
588 | * Returns pointer to registered object with id, which is next number to |
589 | * given id. |
590 | */ |
591 | |
592 | void *idr_get_next(struct idr *idp, int *nextidp) |
593 | { |
594 | struct idr_layer *p, *pa[MAX_LEVEL]; |
595 | struct idr_layer **paa = &pa[0]; |
596 | int id = *nextidp; |
597 | int n, max; |
598 | |
599 | /* find first ent */ |
600 | n = idp->layers * IDR_BITS; |
601 | max = 1 << n; |
602 | p = rcu_dereference(idp->top); |
603 | if (!p) |
604 | return NULL; |
605 | |
606 | while (id < max) { |
607 | while (n > 0 && p) { |
608 | n -= IDR_BITS; |
609 | *paa++ = p; |
610 | p = rcu_dereference(p->ary[(id >> n) & IDR_MASK]); |
611 | } |
612 | |
613 | if (p) { |
614 | *nextidp = id; |
615 | return p; |
616 | } |
617 | |
618 | id += 1 << n; |
619 | while (n < fls(id)) { |
620 | n += IDR_BITS; |
621 | p = *--paa; |
622 | } |
623 | } |
624 | return NULL; |
625 | } |
626 | |
627 | |
628 | |
629 | /** |
630 | * idr_replace - replace pointer for given id |
631 | * @idp: idr handle |
632 | * @ptr: pointer you want associated with the id |
633 | * @id: lookup key |
634 | * |
635 | * Replace the pointer registered with an id and return the old value. |
636 | * A -ENOENT return indicates that @id was not found. |
637 | * A -EINVAL return indicates that @id was not within valid constraints. |
638 | * |
639 | * The caller must serialize with writers. |
640 | */ |
641 | void *idr_replace(struct idr *idp, void *ptr, int id) |
642 | { |
643 | int n; |
644 | struct idr_layer *p, *old_p; |
645 | |
646 | p = idp->top; |
647 | if (!p) |
648 | return ERR_PTR(-EINVAL); |
649 | |
650 | n = (p->layer+1) * IDR_BITS; |
651 | |
652 | id &= MAX_ID_MASK; |
653 | |
654 | if (id >= (1 << n)) |
655 | return ERR_PTR(-EINVAL); |
656 | |
657 | n -= IDR_BITS; |
658 | while ((n > 0) && p) { |
659 | p = p->ary[(id >> n) & IDR_MASK]; |
660 | n -= IDR_BITS; |
661 | } |
662 | |
663 | n = id & IDR_MASK; |
664 | if (unlikely(p == NULL || !test_bit(n, &p->bitmap))) |
665 | return ERR_PTR(-ENOENT); |
666 | |
667 | old_p = p->ary[n]; |
668 | rcu_assign_pointer(p->ary[n], ptr); |
669 | |
670 | return old_p; |
671 | } |
672 | EXPORT_SYMBOL(idr_replace); |
673 | |
674 | void __init idr_init_cache(void) |
675 | { |
676 | idr_layer_cache = kmem_cache_create("idr_layer_cache", |
677 | sizeof(struct idr_layer), 0, SLAB_PANIC, NULL); |
678 | } |
679 | |
680 | /** |
681 | * idr_init - initialize idr handle |
682 | * @idp: idr handle |
683 | * |
684 | * This function is use to set up the handle (@idp) that you will pass |
685 | * to the rest of the functions. |
686 | */ |
687 | void idr_init(struct idr *idp) |
688 | { |
689 | memset(idp, 0, sizeof(struct idr)); |
690 | spin_lock_init(&idp->lock); |
691 | } |
692 | EXPORT_SYMBOL(idr_init); |
693 | |
694 | |
695 | /* |
696 | * IDA - IDR based ID allocator |
697 | * |
698 | * this is id allocator without id -> pointer translation. Memory |
699 | * usage is much lower than full blown idr because each id only |
700 | * occupies a bit. ida uses a custom leaf node which contains |
701 | * IDA_BITMAP_BITS slots. |
702 | * |
703 | * 2007-04-25 written by Tejun Heo <htejun@gmail.com> |
704 | */ |
705 | |
706 | static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap) |
707 | { |
708 | unsigned long flags; |
709 | |
710 | if (!ida->free_bitmap) { |
711 | spin_lock_irqsave(&ida->idr.lock, flags); |
712 | if (!ida->free_bitmap) { |
713 | ida->free_bitmap = bitmap; |
714 | bitmap = NULL; |
715 | } |
716 | spin_unlock_irqrestore(&ida->idr.lock, flags); |
717 | } |
718 | |
719 | kfree(bitmap); |
720 | } |
721 | |
722 | /** |
723 | * ida_pre_get - reserve resources for ida allocation |
724 | * @ida: ida handle |
725 | * @gfp_mask: memory allocation flag |
726 | * |
727 | * This function should be called prior to locking and calling the |
728 | * following function. It preallocates enough memory to satisfy the |
729 | * worst possible allocation. |
730 | * |
731 | * If the system is REALLY out of memory this function returns 0, |
732 | * otherwise 1. |
733 | */ |
734 | int ida_pre_get(struct ida *ida, gfp_t gfp_mask) |
735 | { |
736 | /* allocate idr_layers */ |
737 | if (!idr_pre_get(&ida->idr, gfp_mask)) |
738 | return 0; |
739 | |
740 | /* allocate free_bitmap */ |
741 | if (!ida->free_bitmap) { |
742 | struct ida_bitmap *bitmap; |
743 | |
744 | bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask); |
745 | if (!bitmap) |
746 | return 0; |
747 | |
748 | free_bitmap(ida, bitmap); |
749 | } |
750 | |
751 | return 1; |
752 | } |
753 | EXPORT_SYMBOL(ida_pre_get); |
754 | |
755 | /** |
756 | * ida_get_new_above - allocate new ID above or equal to a start id |
757 | * @ida: ida handle |
758 | * @staring_id: id to start search at |
759 | * @p_id: pointer to the allocated handle |
760 | * |
761 | * Allocate new ID above or equal to @ida. It should be called with |
762 | * any required locks. |
763 | * |
764 | * If memory is required, it will return -EAGAIN, you should unlock |
765 | * and go back to the ida_pre_get() call. If the ida is full, it will |
766 | * return -ENOSPC. |
767 | * |
768 | * @p_id returns a value in the range @starting_id ... 0x7fffffff. |
769 | */ |
770 | int ida_get_new_above(struct ida *ida, int starting_id, int *p_id) |
771 | { |
772 | struct idr_layer *pa[MAX_LEVEL]; |
773 | struct ida_bitmap *bitmap; |
774 | unsigned long flags; |
775 | int idr_id = starting_id / IDA_BITMAP_BITS; |
776 | int offset = starting_id % IDA_BITMAP_BITS; |
777 | int t, id; |
778 | |
779 | restart: |
780 | /* get vacant slot */ |
781 | t = idr_get_empty_slot(&ida->idr, idr_id, pa); |
782 | if (t < 0) |
783 | return _idr_rc_to_errno(t); |
784 | |
785 | if (t * IDA_BITMAP_BITS >= MAX_ID_BIT) |
786 | return -ENOSPC; |
787 | |
788 | if (t != idr_id) |
789 | offset = 0; |
790 | idr_id = t; |
791 | |
792 | /* if bitmap isn't there, create a new one */ |
793 | bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK]; |
794 | if (!bitmap) { |
795 | spin_lock_irqsave(&ida->idr.lock, flags); |
796 | bitmap = ida->free_bitmap; |
797 | ida->free_bitmap = NULL; |
798 | spin_unlock_irqrestore(&ida->idr.lock, flags); |
799 | |
800 | if (!bitmap) |
801 | return -EAGAIN; |
802 | |
803 | memset(bitmap, 0, sizeof(struct ida_bitmap)); |
804 | rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK], |
805 | (void *)bitmap); |
806 | pa[0]->count++; |
807 | } |
808 | |
809 | /* lookup for empty slot */ |
810 | t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset); |
811 | if (t == IDA_BITMAP_BITS) { |
812 | /* no empty slot after offset, continue to the next chunk */ |
813 | idr_id++; |
814 | offset = 0; |
815 | goto restart; |
816 | } |
817 | |
818 | id = idr_id * IDA_BITMAP_BITS + t; |
819 | if (id >= MAX_ID_BIT) |
820 | return -ENOSPC; |
821 | |
822 | __set_bit(t, bitmap->bitmap); |
823 | if (++bitmap->nr_busy == IDA_BITMAP_BITS) |
824 | idr_mark_full(pa, idr_id); |
825 | |
826 | *p_id = id; |
827 | |
828 | /* Each leaf node can handle nearly a thousand slots and the |
829 | * whole idea of ida is to have small memory foot print. |
830 | * Throw away extra resources one by one after each successful |
831 | * allocation. |
832 | */ |
833 | if (ida->idr.id_free_cnt || ida->free_bitmap) { |
834 | struct idr_layer *p = get_from_free_list(&ida->idr); |
835 | if (p) |
836 | kmem_cache_free(idr_layer_cache, p); |
837 | } |
838 | |
839 | return 0; |
840 | } |
841 | EXPORT_SYMBOL(ida_get_new_above); |
842 | |
843 | /** |
844 | * ida_get_new - allocate new ID |
845 | * @ida: idr handle |
846 | * @p_id: pointer to the allocated handle |
847 | * |
848 | * Allocate new ID. It should be called with any required locks. |
849 | * |
850 | * If memory is required, it will return -EAGAIN, you should unlock |
851 | * and go back to the idr_pre_get() call. If the idr is full, it will |
852 | * return -ENOSPC. |
853 | * |
854 | * @id returns a value in the range 0 ... 0x7fffffff. |
855 | */ |
856 | int ida_get_new(struct ida *ida, int *p_id) |
857 | { |
858 | return ida_get_new_above(ida, 0, p_id); |
859 | } |
860 | EXPORT_SYMBOL(ida_get_new); |
861 | |
862 | /** |
863 | * ida_remove - remove the given ID |
864 | * @ida: ida handle |
865 | * @id: ID to free |
866 | */ |
867 | void ida_remove(struct ida *ida, int id) |
868 | { |
869 | struct idr_layer *p = ida->idr.top; |
870 | int shift = (ida->idr.layers - 1) * IDR_BITS; |
871 | int idr_id = id / IDA_BITMAP_BITS; |
872 | int offset = id % IDA_BITMAP_BITS; |
873 | int n; |
874 | struct ida_bitmap *bitmap; |
875 | |
876 | /* clear full bits while looking up the leaf idr_layer */ |
877 | while ((shift > 0) && p) { |
878 | n = (idr_id >> shift) & IDR_MASK; |
879 | __clear_bit(n, &p->bitmap); |
880 | p = p->ary[n]; |
881 | shift -= IDR_BITS; |
882 | } |
883 | |
884 | if (p == NULL) |
885 | goto err; |
886 | |
887 | n = idr_id & IDR_MASK; |
888 | __clear_bit(n, &p->bitmap); |
889 | |
890 | bitmap = (void *)p->ary[n]; |
891 | if (!test_bit(offset, bitmap->bitmap)) |
892 | goto err; |
893 | |
894 | /* update bitmap and remove it if empty */ |
895 | __clear_bit(offset, bitmap->bitmap); |
896 | if (--bitmap->nr_busy == 0) { |
897 | __set_bit(n, &p->bitmap); /* to please idr_remove() */ |
898 | idr_remove(&ida->idr, idr_id); |
899 | free_bitmap(ida, bitmap); |
900 | } |
901 | |
902 | return; |
903 | |
904 | err: |
905 | printk(KERN_WARNING |
906 | "ida_remove called for id=%d which is not allocated.\n", id); |
907 | } |
908 | EXPORT_SYMBOL(ida_remove); |
909 | |
910 | /** |
911 | * ida_destroy - release all cached layers within an ida tree |
912 | * ida: ida handle |
913 | */ |
914 | void ida_destroy(struct ida *ida) |
915 | { |
916 | idr_destroy(&ida->idr); |
917 | kfree(ida->free_bitmap); |
918 | } |
919 | EXPORT_SYMBOL(ida_destroy); |
920 | |
921 | /** |
922 | * ida_init - initialize ida handle |
923 | * @ida: ida handle |
924 | * |
925 | * This function is use to set up the handle (@ida) that you will pass |
926 | * to the rest of the functions. |
927 | */ |
928 | void ida_init(struct ida *ida) |
929 | { |
930 | memset(ida, 0, sizeof(struct ida)); |
931 | idr_init(&ida->idr); |
932 | |
933 | } |
934 | EXPORT_SYMBOL(ida_init); |
935 |
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