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Source at commit b05a5adf03613de371c77c3235f7d970d7cd0c71 created 13 years 1 month ago. By Lars-Peter Clausen, NAND: Optimize reading the eec data for the JZ4740 (evil hack) | |
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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 - reserve resources for idr allocation |
110 | * @idp: idr handle |
111 | * @gfp_mask: memory allocation flags |
112 | * |
113 | * This function should be called prior to calling the idr_get_new* functions. |
114 | * It preallocates enough memory to satisfy the worst possible allocation. The |
115 | * caller should pass in GFP_KERNEL if possible. This of course requires that |
116 | * no spinning locks be held. |
117 | * |
118 | * If the system is REALLY out of memory this function returns %0, |
119 | * otherwise %1. |
120 | */ |
121 | int idr_pre_get(struct idr *idp, gfp_t gfp_mask) |
122 | { |
123 | while (idp->id_free_cnt < IDR_FREE_MAX) { |
124 | struct idr_layer *new; |
125 | new = kmem_cache_zalloc(idr_layer_cache, gfp_mask); |
126 | if (new == NULL) |
127 | return (0); |
128 | move_to_free_list(idp, new); |
129 | } |
130 | return 1; |
131 | } |
132 | EXPORT_SYMBOL(idr_pre_get); |
133 | |
134 | static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa) |
135 | { |
136 | int n, m, sh; |
137 | struct idr_layer *p, *new; |
138 | int l, id, oid; |
139 | unsigned long bm; |
140 | |
141 | id = *starting_id; |
142 | restart: |
143 | p = idp->top; |
144 | l = idp->layers; |
145 | pa[l--] = NULL; |
146 | while (1) { |
147 | /* |
148 | * We run around this while until we reach the leaf node... |
149 | */ |
150 | n = (id >> (IDR_BITS*l)) & IDR_MASK; |
151 | bm = ~p->bitmap; |
152 | m = find_next_bit(&bm, IDR_SIZE, n); |
153 | if (m == IDR_SIZE) { |
154 | /* no space available go back to previous layer. */ |
155 | l++; |
156 | oid = id; |
157 | id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1; |
158 | |
159 | /* if already at the top layer, we need to grow */ |
160 | if (id >= 1 << (idp->layers * IDR_BITS)) { |
161 | *starting_id = id; |
162 | return IDR_NEED_TO_GROW; |
163 | } |
164 | p = pa[l]; |
165 | BUG_ON(!p); |
166 | |
167 | /* If we need to go up one layer, continue the |
168 | * loop; otherwise, restart from the top. |
169 | */ |
170 | sh = IDR_BITS * (l + 1); |
171 | if (oid >> sh == id >> sh) |
172 | continue; |
173 | else |
174 | goto restart; |
175 | } |
176 | if (m != n) { |
177 | sh = IDR_BITS*l; |
178 | id = ((id >> sh) ^ n ^ m) << sh; |
179 | } |
180 | if ((id >= MAX_ID_BIT) || (id < 0)) |
181 | return IDR_NOMORE_SPACE; |
182 | if (l == 0) |
183 | break; |
184 | /* |
185 | * Create the layer below if it is missing. |
186 | */ |
187 | if (!p->ary[m]) { |
188 | new = get_from_free_list(idp); |
189 | if (!new) |
190 | return -1; |
191 | new->layer = l-1; |
192 | rcu_assign_pointer(p->ary[m], new); |
193 | p->count++; |
194 | } |
195 | pa[l--] = p; |
196 | p = p->ary[m]; |
197 | } |
198 | |
199 | pa[l] = p; |
200 | return id; |
201 | } |
202 | |
203 | static int idr_get_empty_slot(struct idr *idp, int starting_id, |
204 | struct idr_layer **pa) |
205 | { |
206 | struct idr_layer *p, *new; |
207 | int layers, v, id; |
208 | unsigned long flags; |
209 | |
210 | id = starting_id; |
211 | build_up: |
212 | p = idp->top; |
213 | layers = idp->layers; |
214 | if (unlikely(!p)) { |
215 | if (!(p = get_from_free_list(idp))) |
216 | return -1; |
217 | p->layer = 0; |
218 | layers = 1; |
219 | } |
220 | /* |
221 | * Add a new layer to the top of the tree if the requested |
222 | * id is larger than the currently allocated space. |
223 | */ |
224 | while ((layers < (MAX_LEVEL - 1)) && (id >= (1 << (layers*IDR_BITS)))) { |
225 | layers++; |
226 | if (!p->count) { |
227 | /* special case: if the tree is currently empty, |
228 | * then we grow the tree by moving the top node |
229 | * upwards. |
230 | */ |
231 | p->layer++; |
232 | continue; |
233 | } |
234 | if (!(new = get_from_free_list(idp))) { |
235 | /* |
236 | * The allocation failed. If we built part of |
237 | * the structure tear it down. |
238 | */ |
239 | spin_lock_irqsave(&idp->lock, flags); |
240 | for (new = p; p && p != idp->top; new = p) { |
241 | p = p->ary[0]; |
242 | new->ary[0] = NULL; |
243 | new->bitmap = new->count = 0; |
244 | __move_to_free_list(idp, new); |
245 | } |
246 | spin_unlock_irqrestore(&idp->lock, flags); |
247 | return -1; |
248 | } |
249 | new->ary[0] = p; |
250 | new->count = 1; |
251 | new->layer = layers-1; |
252 | if (p->bitmap == IDR_FULL) |
253 | __set_bit(0, &new->bitmap); |
254 | p = new; |
255 | } |
256 | rcu_assign_pointer(idp->top, p); |
257 | idp->layers = layers; |
258 | v = sub_alloc(idp, &id, pa); |
259 | if (v == IDR_NEED_TO_GROW) |
260 | goto build_up; |
261 | return(v); |
262 | } |
263 | |
264 | static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id) |
265 | { |
266 | struct idr_layer *pa[MAX_LEVEL]; |
267 | int id; |
268 | |
269 | id = idr_get_empty_slot(idp, starting_id, pa); |
270 | if (id >= 0) { |
271 | /* |
272 | * Successfully found an empty slot. Install the user |
273 | * pointer and mark the slot full. |
274 | */ |
275 | rcu_assign_pointer(pa[0]->ary[id & IDR_MASK], |
276 | (struct idr_layer *)ptr); |
277 | pa[0]->count++; |
278 | idr_mark_full(pa, id); |
279 | } |
280 | |
281 | return id; |
282 | } |
283 | |
284 | /** |
285 | * idr_get_new_above - allocate new idr entry above or equal to a start id |
286 | * @idp: idr handle |
287 | * @ptr: pointer you want associated with the id |
288 | * @starting_id: id to start search at |
289 | * @id: pointer to the allocated handle |
290 | * |
291 | * This is the allocate id function. It should be called with any |
292 | * required locks. |
293 | * |
294 | * If allocation from IDR's private freelist fails, idr_get_new_above() will |
295 | * return %-EAGAIN. The caller should retry the idr_pre_get() call to refill |
296 | * IDR's preallocation and then retry the idr_get_new_above() call. |
297 | * |
298 | * If the idr is full idr_get_new_above() will return %-ENOSPC. |
299 | * |
300 | * @id returns a value in the range @starting_id ... %0x7fffffff |
301 | */ |
302 | int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id) |
303 | { |
304 | int rv; |
305 | |
306 | rv = idr_get_new_above_int(idp, ptr, starting_id); |
307 | /* |
308 | * This is a cheap hack until the IDR code can be fixed to |
309 | * return proper error values. |
310 | */ |
311 | if (rv < 0) |
312 | return _idr_rc_to_errno(rv); |
313 | *id = rv; |
314 | return 0; |
315 | } |
316 | EXPORT_SYMBOL(idr_get_new_above); |
317 | |
318 | /** |
319 | * idr_get_new - allocate new idr entry |
320 | * @idp: idr handle |
321 | * @ptr: pointer you want associated with the id |
322 | * @id: pointer to the allocated handle |
323 | * |
324 | * If allocation from IDR's private freelist fails, idr_get_new_above() will |
325 | * return %-EAGAIN. The caller should retry the idr_pre_get() call to refill |
326 | * IDR's preallocation and then retry the idr_get_new_above() call. |
327 | * |
328 | * If the idr is full idr_get_new_above() will return %-ENOSPC. |
329 | * |
330 | * @id returns a value in the range %0 ... %0x7fffffff |
331 | */ |
332 | int idr_get_new(struct idr *idp, void *ptr, int *id) |
333 | { |
334 | int rv; |
335 | |
336 | rv = idr_get_new_above_int(idp, ptr, 0); |
337 | /* |
338 | * This is a cheap hack until the IDR code can be fixed to |
339 | * return proper error values. |
340 | */ |
341 | if (rv < 0) |
342 | return _idr_rc_to_errno(rv); |
343 | *id = rv; |
344 | return 0; |
345 | } |
346 | EXPORT_SYMBOL(idr_get_new); |
347 | |
348 | static void idr_remove_warning(int id) |
349 | { |
350 | printk(KERN_WARNING |
351 | "idr_remove called for id=%d which is not allocated.\n", id); |
352 | dump_stack(); |
353 | } |
354 | |
355 | static void sub_remove(struct idr *idp, int shift, int id) |
356 | { |
357 | struct idr_layer *p = idp->top; |
358 | struct idr_layer **pa[MAX_LEVEL]; |
359 | struct idr_layer ***paa = &pa[0]; |
360 | struct idr_layer *to_free; |
361 | int n; |
362 | |
363 | *paa = NULL; |
364 | *++paa = &idp->top; |
365 | |
366 | while ((shift > 0) && p) { |
367 | n = (id >> shift) & IDR_MASK; |
368 | __clear_bit(n, &p->bitmap); |
369 | *++paa = &p->ary[n]; |
370 | p = p->ary[n]; |
371 | shift -= IDR_BITS; |
372 | } |
373 | n = id & IDR_MASK; |
374 | if (likely(p != NULL && test_bit(n, &p->bitmap))){ |
375 | __clear_bit(n, &p->bitmap); |
376 | rcu_assign_pointer(p->ary[n], NULL); |
377 | to_free = NULL; |
378 | while(*paa && ! --((**paa)->count)){ |
379 | if (to_free) |
380 | free_layer(to_free); |
381 | to_free = **paa; |
382 | **paa-- = NULL; |
383 | } |
384 | if (!*paa) |
385 | idp->layers = 0; |
386 | if (to_free) |
387 | free_layer(to_free); |
388 | } else |
389 | idr_remove_warning(id); |
390 | } |
391 | |
392 | /** |
393 | * idr_remove - remove the given id and free its slot |
394 | * @idp: idr handle |
395 | * @id: unique key |
396 | */ |
397 | void idr_remove(struct idr *idp, int id) |
398 | { |
399 | struct idr_layer *p; |
400 | struct idr_layer *to_free; |
401 | |
402 | /* Mask off upper bits we don't use for the search. */ |
403 | id &= MAX_ID_MASK; |
404 | |
405 | sub_remove(idp, (idp->layers - 1) * IDR_BITS, id); |
406 | if (idp->top && idp->top->count == 1 && (idp->layers > 1) && |
407 | idp->top->ary[0]) { |
408 | /* |
409 | * Single child at leftmost slot: we can shrink the tree. |
410 | * This level is not needed anymore since when layers are |
411 | * inserted, they are inserted at the top of the existing |
412 | * tree. |
413 | */ |
414 | to_free = idp->top; |
415 | p = idp->top->ary[0]; |
416 | rcu_assign_pointer(idp->top, p); |
417 | --idp->layers; |
418 | to_free->bitmap = to_free->count = 0; |
419 | free_layer(to_free); |
420 | } |
421 | while (idp->id_free_cnt >= IDR_FREE_MAX) { |
422 | p = get_from_free_list(idp); |
423 | /* |
424 | * Note: we don't call the rcu callback here, since the only |
425 | * layers that fall into the freelist are those that have been |
426 | * preallocated. |
427 | */ |
428 | kmem_cache_free(idr_layer_cache, p); |
429 | } |
430 | return; |
431 | } |
432 | EXPORT_SYMBOL(idr_remove); |
433 | |
434 | /** |
435 | * idr_remove_all - remove all ids from the given idr tree |
436 | * @idp: idr handle |
437 | * |
438 | * idr_destroy() only frees up unused, cached idp_layers, but this |
439 | * function will remove all id mappings and leave all idp_layers |
440 | * unused. |
441 | * |
442 | * A typical clean-up sequence for objects stored in an idr tree will |
443 | * use idr_for_each() to free all objects, if necessay, then |
444 | * idr_remove_all() to remove all ids, and idr_destroy() to free |
445 | * up the cached idr_layers. |
446 | */ |
447 | void idr_remove_all(struct idr *idp) |
448 | { |
449 | int n, id, max; |
450 | int bt_mask; |
451 | struct idr_layer *p; |
452 | struct idr_layer *pa[MAX_LEVEL]; |
453 | struct idr_layer **paa = &pa[0]; |
454 | |
455 | n = idp->layers * IDR_BITS; |
456 | p = idp->top; |
457 | rcu_assign_pointer(idp->top, NULL); |
458 | max = 1 << n; |
459 | |
460 | id = 0; |
461 | while (id < max) { |
462 | while (n > IDR_BITS && p) { |
463 | n -= IDR_BITS; |
464 | *paa++ = p; |
465 | p = p->ary[(id >> n) & IDR_MASK]; |
466 | } |
467 | |
468 | bt_mask = id; |
469 | id += 1 << n; |
470 | /* Get the highest bit that the above add changed from 0->1. */ |
471 | while (n < fls(id ^ bt_mask)) { |
472 | if (p) |
473 | free_layer(p); |
474 | n += IDR_BITS; |
475 | p = *--paa; |
476 | } |
477 | } |
478 | idp->layers = 0; |
479 | } |
480 | EXPORT_SYMBOL(idr_remove_all); |
481 | |
482 | /** |
483 | * idr_destroy - release all cached layers within an idr tree |
484 | * @idp: idr handle |
485 | */ |
486 | void idr_destroy(struct idr *idp) |
487 | { |
488 | while (idp->id_free_cnt) { |
489 | struct idr_layer *p = get_from_free_list(idp); |
490 | kmem_cache_free(idr_layer_cache, p); |
491 | } |
492 | } |
493 | EXPORT_SYMBOL(idr_destroy); |
494 | |
495 | /** |
496 | * idr_find - return pointer for given id |
497 | * @idp: idr handle |
498 | * @id: lookup key |
499 | * |
500 | * Return the pointer given the id it has been registered with. A %NULL |
501 | * return indicates that @id is not valid or you passed %NULL in |
502 | * idr_get_new(). |
503 | * |
504 | * This function can be called under rcu_read_lock(), given that the leaf |
505 | * pointers lifetimes are correctly managed. |
506 | */ |
507 | void *idr_find(struct idr *idp, int id) |
508 | { |
509 | int n; |
510 | struct idr_layer *p; |
511 | |
512 | p = rcu_dereference_raw(idp->top); |
513 | if (!p) |
514 | return NULL; |
515 | n = (p->layer+1) * IDR_BITS; |
516 | |
517 | /* Mask off upper bits we don't use for the search. */ |
518 | id &= MAX_ID_MASK; |
519 | |
520 | if (id >= (1 << n)) |
521 | return NULL; |
522 | BUG_ON(n == 0); |
523 | |
524 | while (n > 0 && p) { |
525 | n -= IDR_BITS; |
526 | BUG_ON(n != p->layer*IDR_BITS); |
527 | p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]); |
528 | } |
529 | return((void *)p); |
530 | } |
531 | EXPORT_SYMBOL(idr_find); |
532 | |
533 | /** |
534 | * idr_for_each - iterate through all stored pointers |
535 | * @idp: idr handle |
536 | * @fn: function to be called for each pointer |
537 | * @data: data passed back to callback function |
538 | * |
539 | * Iterate over the pointers registered with the given idr. The |
540 | * callback function will be called for each pointer currently |
541 | * registered, passing the id, the pointer and the data pointer passed |
542 | * to this function. It is not safe to modify the idr tree while in |
543 | * the callback, so functions such as idr_get_new and idr_remove are |
544 | * not allowed. |
545 | * |
546 | * We check the return of @fn each time. If it returns anything other |
547 | * than %0, we break out and return that value. |
548 | * |
549 | * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove(). |
550 | */ |
551 | int idr_for_each(struct idr *idp, |
552 | int (*fn)(int id, void *p, void *data), void *data) |
553 | { |
554 | int n, id, max, error = 0; |
555 | struct idr_layer *p; |
556 | struct idr_layer *pa[MAX_LEVEL]; |
557 | struct idr_layer **paa = &pa[0]; |
558 | |
559 | n = idp->layers * IDR_BITS; |
560 | p = rcu_dereference_raw(idp->top); |
561 | max = 1 << n; |
562 | |
563 | id = 0; |
564 | while (id < max) { |
565 | while (n > 0 && p) { |
566 | n -= IDR_BITS; |
567 | *paa++ = p; |
568 | p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]); |
569 | } |
570 | |
571 | if (p) { |
572 | error = fn(id, (void *)p, data); |
573 | if (error) |
574 | break; |
575 | } |
576 | |
577 | id += 1 << n; |
578 | while (n < fls(id)) { |
579 | n += IDR_BITS; |
580 | p = *--paa; |
581 | } |
582 | } |
583 | |
584 | return error; |
585 | } |
586 | EXPORT_SYMBOL(idr_for_each); |
587 | |
588 | /** |
589 | * idr_get_next - lookup next object of id to given id. |
590 | * @idp: idr handle |
591 | * @nextidp: pointer to lookup key |
592 | * |
593 | * Returns pointer to registered object with id, which is next number to |
594 | * given id. After being looked up, *@nextidp will be updated for the next |
595 | * iteration. |
596 | */ |
597 | |
598 | void *idr_get_next(struct idr *idp, int *nextidp) |
599 | { |
600 | struct idr_layer *p, *pa[MAX_LEVEL]; |
601 | struct idr_layer **paa = &pa[0]; |
602 | int id = *nextidp; |
603 | int n, max; |
604 | |
605 | /* find first ent */ |
606 | n = idp->layers * IDR_BITS; |
607 | max = 1 << n; |
608 | p = rcu_dereference_raw(idp->top); |
609 | if (!p) |
610 | return NULL; |
611 | |
612 | while (id < max) { |
613 | while (n > 0 && p) { |
614 | n -= IDR_BITS; |
615 | *paa++ = p; |
616 | p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]); |
617 | } |
618 | |
619 | if (p) { |
620 | *nextidp = id; |
621 | return p; |
622 | } |
623 | |
624 | id += 1 << n; |
625 | while (n < fls(id)) { |
626 | n += IDR_BITS; |
627 | p = *--paa; |
628 | } |
629 | } |
630 | return NULL; |
631 | } |
632 | EXPORT_SYMBOL(idr_get_next); |
633 | |
634 | |
635 | /** |
636 | * idr_replace - replace pointer for given id |
637 | * @idp: idr handle |
638 | * @ptr: pointer you want associated with the id |
639 | * @id: lookup key |
640 | * |
641 | * Replace the pointer registered with an id and return the old value. |
642 | * A %-ENOENT return indicates that @id was not found. |
643 | * A %-EINVAL return indicates that @id was not within valid constraints. |
644 | * |
645 | * The caller must serialize with writers. |
646 | */ |
647 | void *idr_replace(struct idr *idp, void *ptr, int id) |
648 | { |
649 | int n; |
650 | struct idr_layer *p, *old_p; |
651 | |
652 | p = idp->top; |
653 | if (!p) |
654 | return ERR_PTR(-EINVAL); |
655 | |
656 | n = (p->layer+1) * IDR_BITS; |
657 | |
658 | id &= MAX_ID_MASK; |
659 | |
660 | if (id >= (1 << n)) |
661 | return ERR_PTR(-EINVAL); |
662 | |
663 | n -= IDR_BITS; |
664 | while ((n > 0) && p) { |
665 | p = p->ary[(id >> n) & IDR_MASK]; |
666 | n -= IDR_BITS; |
667 | } |
668 | |
669 | n = id & IDR_MASK; |
670 | if (unlikely(p == NULL || !test_bit(n, &p->bitmap))) |
671 | return ERR_PTR(-ENOENT); |
672 | |
673 | old_p = p->ary[n]; |
674 | rcu_assign_pointer(p->ary[n], ptr); |
675 | |
676 | return old_p; |
677 | } |
678 | EXPORT_SYMBOL(idr_replace); |
679 | |
680 | void __init idr_init_cache(void) |
681 | { |
682 | idr_layer_cache = kmem_cache_create("idr_layer_cache", |
683 | sizeof(struct idr_layer), 0, SLAB_PANIC, NULL); |
684 | } |
685 | |
686 | /** |
687 | * idr_init - initialize idr handle |
688 | * @idp: idr handle |
689 | * |
690 | * This function is use to set up the handle (@idp) that you will pass |
691 | * to the rest of the functions. |
692 | */ |
693 | void idr_init(struct idr *idp) |
694 | { |
695 | memset(idp, 0, sizeof(struct idr)); |
696 | spin_lock_init(&idp->lock); |
697 | } |
698 | EXPORT_SYMBOL(idr_init); |
699 | |
700 | |
701 | /** |
702 | * DOC: IDA description |
703 | * IDA - IDR based ID allocator |
704 | * |
705 | * This is id allocator without id -> pointer translation. Memory |
706 | * usage is much lower than full blown idr because each id only |
707 | * occupies a bit. ida uses a custom leaf node which contains |
708 | * IDA_BITMAP_BITS slots. |
709 | * |
710 | * 2007-04-25 written by Tejun Heo <htejun@gmail.com> |
711 | */ |
712 | |
713 | static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap) |
714 | { |
715 | unsigned long flags; |
716 | |
717 | if (!ida->free_bitmap) { |
718 | spin_lock_irqsave(&ida->idr.lock, flags); |
719 | if (!ida->free_bitmap) { |
720 | ida->free_bitmap = bitmap; |
721 | bitmap = NULL; |
722 | } |
723 | spin_unlock_irqrestore(&ida->idr.lock, flags); |
724 | } |
725 | |
726 | kfree(bitmap); |
727 | } |
728 | |
729 | /** |
730 | * ida_pre_get - reserve resources for ida allocation |
731 | * @ida: ida handle |
732 | * @gfp_mask: memory allocation flag |
733 | * |
734 | * This function should be called prior to locking and calling the |
735 | * following function. It preallocates enough memory to satisfy the |
736 | * worst possible allocation. |
737 | * |
738 | * If the system is REALLY out of memory this function returns %0, |
739 | * otherwise %1. |
740 | */ |
741 | int ida_pre_get(struct ida *ida, gfp_t gfp_mask) |
742 | { |
743 | /* allocate idr_layers */ |
744 | if (!idr_pre_get(&ida->idr, gfp_mask)) |
745 | return 0; |
746 | |
747 | /* allocate free_bitmap */ |
748 | if (!ida->free_bitmap) { |
749 | struct ida_bitmap *bitmap; |
750 | |
751 | bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask); |
752 | if (!bitmap) |
753 | return 0; |
754 | |
755 | free_bitmap(ida, bitmap); |
756 | } |
757 | |
758 | return 1; |
759 | } |
760 | EXPORT_SYMBOL(ida_pre_get); |
761 | |
762 | /** |
763 | * ida_get_new_above - allocate new ID above or equal to a start id |
764 | * @ida: ida handle |
765 | * @starting_id: id to start search at |
766 | * @p_id: pointer to the allocated handle |
767 | * |
768 | * Allocate new ID above or equal to @ida. It should be called with |
769 | * any required locks. |
770 | * |
771 | * If memory is required, it will return %-EAGAIN, you should unlock |
772 | * and go back to the ida_pre_get() call. If the ida is full, it will |
773 | * return %-ENOSPC. |
774 | * |
775 | * @p_id returns a value in the range @starting_id ... %0x7fffffff. |
776 | */ |
777 | int ida_get_new_above(struct ida *ida, int starting_id, int *p_id) |
778 | { |
779 | struct idr_layer *pa[MAX_LEVEL]; |
780 | struct ida_bitmap *bitmap; |
781 | unsigned long flags; |
782 | int idr_id = starting_id / IDA_BITMAP_BITS; |
783 | int offset = starting_id % IDA_BITMAP_BITS; |
784 | int t, id; |
785 | |
786 | restart: |
787 | /* get vacant slot */ |
788 | t = idr_get_empty_slot(&ida->idr, idr_id, pa); |
789 | if (t < 0) |
790 | return _idr_rc_to_errno(t); |
791 | |
792 | if (t * IDA_BITMAP_BITS >= MAX_ID_BIT) |
793 | return -ENOSPC; |
794 | |
795 | if (t != idr_id) |
796 | offset = 0; |
797 | idr_id = t; |
798 | |
799 | /* if bitmap isn't there, create a new one */ |
800 | bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK]; |
801 | if (!bitmap) { |
802 | spin_lock_irqsave(&ida->idr.lock, flags); |
803 | bitmap = ida->free_bitmap; |
804 | ida->free_bitmap = NULL; |
805 | spin_unlock_irqrestore(&ida->idr.lock, flags); |
806 | |
807 | if (!bitmap) |
808 | return -EAGAIN; |
809 | |
810 | memset(bitmap, 0, sizeof(struct ida_bitmap)); |
811 | rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK], |
812 | (void *)bitmap); |
813 | pa[0]->count++; |
814 | } |
815 | |
816 | /* lookup for empty slot */ |
817 | t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset); |
818 | if (t == IDA_BITMAP_BITS) { |
819 | /* no empty slot after offset, continue to the next chunk */ |
820 | idr_id++; |
821 | offset = 0; |
822 | goto restart; |
823 | } |
824 | |
825 | id = idr_id * IDA_BITMAP_BITS + t; |
826 | if (id >= MAX_ID_BIT) |
827 | return -ENOSPC; |
828 | |
829 | __set_bit(t, bitmap->bitmap); |
830 | if (++bitmap->nr_busy == IDA_BITMAP_BITS) |
831 | idr_mark_full(pa, idr_id); |
832 | |
833 | *p_id = id; |
834 | |
835 | /* Each leaf node can handle nearly a thousand slots and the |
836 | * whole idea of ida is to have small memory foot print. |
837 | * Throw away extra resources one by one after each successful |
838 | * allocation. |
839 | */ |
840 | if (ida->idr.id_free_cnt || ida->free_bitmap) { |
841 | struct idr_layer *p = get_from_free_list(&ida->idr); |
842 | if (p) |
843 | kmem_cache_free(idr_layer_cache, p); |
844 | } |
845 | |
846 | return 0; |
847 | } |
848 | EXPORT_SYMBOL(ida_get_new_above); |
849 | |
850 | /** |
851 | * ida_get_new - allocate new ID |
852 | * @ida: idr handle |
853 | * @p_id: pointer to the allocated handle |
854 | * |
855 | * Allocate new ID. It should be called with any required locks. |
856 | * |
857 | * If memory is required, it will return %-EAGAIN, you should unlock |
858 | * and go back to the idr_pre_get() call. If the idr is full, it will |
859 | * return %-ENOSPC. |
860 | * |
861 | * @id returns a value in the range %0 ... %0x7fffffff. |
862 | */ |
863 | int ida_get_new(struct ida *ida, int *p_id) |
864 | { |
865 | return ida_get_new_above(ida, 0, p_id); |
866 | } |
867 | EXPORT_SYMBOL(ida_get_new); |
868 | |
869 | /** |
870 | * ida_remove - remove the given ID |
871 | * @ida: ida handle |
872 | * @id: ID to free |
873 | */ |
874 | void ida_remove(struct ida *ida, int id) |
875 | { |
876 | struct idr_layer *p = ida->idr.top; |
877 | int shift = (ida->idr.layers - 1) * IDR_BITS; |
878 | int idr_id = id / IDA_BITMAP_BITS; |
879 | int offset = id % IDA_BITMAP_BITS; |
880 | int n; |
881 | struct ida_bitmap *bitmap; |
882 | |
883 | /* clear full bits while looking up the leaf idr_layer */ |
884 | while ((shift > 0) && p) { |
885 | n = (idr_id >> shift) & IDR_MASK; |
886 | __clear_bit(n, &p->bitmap); |
887 | p = p->ary[n]; |
888 | shift -= IDR_BITS; |
889 | } |
890 | |
891 | if (p == NULL) |
892 | goto err; |
893 | |
894 | n = idr_id & IDR_MASK; |
895 | __clear_bit(n, &p->bitmap); |
896 | |
897 | bitmap = (void *)p->ary[n]; |
898 | if (!test_bit(offset, bitmap->bitmap)) |
899 | goto err; |
900 | |
901 | /* update bitmap and remove it if empty */ |
902 | __clear_bit(offset, bitmap->bitmap); |
903 | if (--bitmap->nr_busy == 0) { |
904 | __set_bit(n, &p->bitmap); /* to please idr_remove() */ |
905 | idr_remove(&ida->idr, idr_id); |
906 | free_bitmap(ida, bitmap); |
907 | } |
908 | |
909 | return; |
910 | |
911 | err: |
912 | printk(KERN_WARNING |
913 | "ida_remove called for id=%d which is not allocated.\n", id); |
914 | } |
915 | EXPORT_SYMBOL(ida_remove); |
916 | |
917 | /** |
918 | * ida_destroy - release all cached layers within an ida tree |
919 | * @ida: ida handle |
920 | */ |
921 | void ida_destroy(struct ida *ida) |
922 | { |
923 | idr_destroy(&ida->idr); |
924 | kfree(ida->free_bitmap); |
925 | } |
926 | EXPORT_SYMBOL(ida_destroy); |
927 | |
928 | /** |
929 | * ida_init - initialize ida handle |
930 | * @ida: ida handle |
931 | * |
932 | * This function is use to set up the handle (@ida) that you will pass |
933 | * to the rest of the functions. |
934 | */ |
935 | void ida_init(struct ida *ida) |
936 | { |
937 | memset(ida, 0, sizeof(struct ida)); |
938 | idr_init(&ida->idr); |
939 | |
940 | } |
941 | EXPORT_SYMBOL(ida_init); |
942 |
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