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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); |