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1da177e4 LT |
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 | * | |
e15ae2dd | 9 | * Small id to pointer translation service. |
1da177e4 | 10 | * |
e15ae2dd | 11 | * It uses a radix tree like structure as a sparse array indexed |
1da177e4 | 12 | * by the id to obtain the pointer. The bitmap makes allocating |
e15ae2dd | 13 | * a new id quick. |
1da177e4 LT |
14 | * |
15 | * You call it to allocate an id (an int) an associate with that id a | |
16 | * pointer or what ever, we treat it as a (void *). You can pass this | |
17 | * id to a user for him to pass back at a later time. You then pass | |
18 | * that id to this code and it returns your pointer. | |
19 | ||
e15ae2dd | 20 | * You can release ids at any time. When all ids are released, most of |
1da177e4 | 21 | * the memory is returned (we keep IDR_FREE_MAX) in a local pool so we |
e15ae2dd | 22 | * don't need to go to the memory "store" during an id allocate, just |
1da177e4 LT |
23 | * so you don't need to be too concerned about locking and conflicts |
24 | * with the slab allocator. | |
25 | */ | |
26 | ||
27 | #ifndef TEST // to test in user space... | |
28 | #include <linux/slab.h> | |
29 | #include <linux/init.h> | |
30 | #include <linux/module.h> | |
31 | #endif | |
5806f07c | 32 | #include <linux/err.h> |
1da177e4 LT |
33 | #include <linux/string.h> |
34 | #include <linux/idr.h> | |
35 | ||
e18b890b | 36 | static struct kmem_cache *idr_layer_cache; |
1da177e4 LT |
37 | |
38 | static struct idr_layer *alloc_layer(struct idr *idp) | |
39 | { | |
40 | struct idr_layer *p; | |
c259cc28 | 41 | unsigned long flags; |
1da177e4 | 42 | |
c259cc28 | 43 | spin_lock_irqsave(&idp->lock, flags); |
1da177e4 LT |
44 | if ((p = idp->id_free)) { |
45 | idp->id_free = p->ary[0]; | |
46 | idp->id_free_cnt--; | |
47 | p->ary[0] = NULL; | |
48 | } | |
c259cc28 | 49 | spin_unlock_irqrestore(&idp->lock, flags); |
1da177e4 LT |
50 | return(p); |
51 | } | |
52 | ||
1eec0056 SR |
53 | /* only called when idp->lock is held */ |
54 | static void __free_layer(struct idr *idp, struct idr_layer *p) | |
55 | { | |
56 | p->ary[0] = idp->id_free; | |
57 | idp->id_free = p; | |
58 | idp->id_free_cnt++; | |
59 | } | |
60 | ||
1da177e4 LT |
61 | static void free_layer(struct idr *idp, struct idr_layer *p) |
62 | { | |
c259cc28 RD |
63 | unsigned long flags; |
64 | ||
1da177e4 LT |
65 | /* |
66 | * Depends on the return element being zeroed. | |
67 | */ | |
c259cc28 | 68 | spin_lock_irqsave(&idp->lock, flags); |
1eec0056 | 69 | __free_layer(idp, p); |
c259cc28 | 70 | spin_unlock_irqrestore(&idp->lock, flags); |
1da177e4 LT |
71 | } |
72 | ||
73 | /** | |
74 | * idr_pre_get - reserver resources for idr allocation | |
75 | * @idp: idr handle | |
76 | * @gfp_mask: memory allocation flags | |
77 | * | |
78 | * This function should be called prior to locking and calling the | |
79 | * following function. It preallocates enough memory to satisfy | |
80 | * the worst possible allocation. | |
81 | * | |
82 | * If the system is REALLY out of memory this function returns 0, | |
83 | * otherwise 1. | |
84 | */ | |
fd4f2df2 | 85 | int idr_pre_get(struct idr *idp, gfp_t gfp_mask) |
1da177e4 LT |
86 | { |
87 | while (idp->id_free_cnt < IDR_FREE_MAX) { | |
88 | struct idr_layer *new; | |
89 | new = kmem_cache_alloc(idr_layer_cache, gfp_mask); | |
e15ae2dd | 90 | if (new == NULL) |
1da177e4 LT |
91 | return (0); |
92 | free_layer(idp, new); | |
93 | } | |
94 | return 1; | |
95 | } | |
96 | EXPORT_SYMBOL(idr_pre_get); | |
97 | ||
98 | static int sub_alloc(struct idr *idp, void *ptr, int *starting_id) | |
99 | { | |
100 | int n, m, sh; | |
101 | struct idr_layer *p, *new; | |
102 | struct idr_layer *pa[MAX_LEVEL]; | |
7aae6dd8 | 103 | int l, id, oid; |
1da177e4 LT |
104 | long bm; |
105 | ||
106 | id = *starting_id; | |
7aae6dd8 | 107 | restart: |
1da177e4 LT |
108 | p = idp->top; |
109 | l = idp->layers; | |
110 | pa[l--] = NULL; | |
111 | while (1) { | |
112 | /* | |
113 | * We run around this while until we reach the leaf node... | |
114 | */ | |
115 | n = (id >> (IDR_BITS*l)) & IDR_MASK; | |
116 | bm = ~p->bitmap; | |
117 | m = find_next_bit(&bm, IDR_SIZE, n); | |
118 | if (m == IDR_SIZE) { | |
119 | /* no space available go back to previous layer. */ | |
120 | l++; | |
7aae6dd8 | 121 | oid = id; |
e15ae2dd | 122 | id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1; |
7aae6dd8 TH |
123 | |
124 | /* if already at the top layer, we need to grow */ | |
1da177e4 LT |
125 | if (!(p = pa[l])) { |
126 | *starting_id = id; | |
127 | return -2; | |
128 | } | |
7aae6dd8 TH |
129 | |
130 | /* If we need to go up one layer, continue the | |
131 | * loop; otherwise, restart from the top. | |
132 | */ | |
133 | sh = IDR_BITS * (l + 1); | |
134 | if (oid >> sh == id >> sh) | |
135 | continue; | |
136 | else | |
137 | goto restart; | |
1da177e4 LT |
138 | } |
139 | if (m != n) { | |
140 | sh = IDR_BITS*l; | |
141 | id = ((id >> sh) ^ n ^ m) << sh; | |
142 | } | |
143 | if ((id >= MAX_ID_BIT) || (id < 0)) | |
144 | return -3; | |
145 | if (l == 0) | |
146 | break; | |
147 | /* | |
148 | * Create the layer below if it is missing. | |
149 | */ | |
150 | if (!p->ary[m]) { | |
151 | if (!(new = alloc_layer(idp))) | |
152 | return -1; | |
153 | p->ary[m] = new; | |
154 | p->count++; | |
155 | } | |
156 | pa[l--] = p; | |
157 | p = p->ary[m]; | |
158 | } | |
159 | /* | |
160 | * We have reached the leaf node, plant the | |
161 | * users pointer and return the raw id. | |
162 | */ | |
163 | p->ary[m] = (struct idr_layer *)ptr; | |
164 | __set_bit(m, &p->bitmap); | |
165 | p->count++; | |
166 | /* | |
167 | * If this layer is full mark the bit in the layer above | |
168 | * to show that this part of the radix tree is full. | |
169 | * This may complete the layer above and require walking | |
170 | * up the radix tree. | |
171 | */ | |
172 | n = id; | |
173 | while (p->bitmap == IDR_FULL) { | |
174 | if (!(p = pa[++l])) | |
175 | break; | |
176 | n = n >> IDR_BITS; | |
177 | __set_bit((n & IDR_MASK), &p->bitmap); | |
178 | } | |
179 | return(id); | |
180 | } | |
181 | ||
182 | static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id) | |
183 | { | |
184 | struct idr_layer *p, *new; | |
185 | int layers, v, id; | |
c259cc28 | 186 | unsigned long flags; |
e15ae2dd | 187 | |
1da177e4 LT |
188 | id = starting_id; |
189 | build_up: | |
190 | p = idp->top; | |
191 | layers = idp->layers; | |
192 | if (unlikely(!p)) { | |
193 | if (!(p = alloc_layer(idp))) | |
194 | return -1; | |
195 | layers = 1; | |
196 | } | |
197 | /* | |
198 | * Add a new layer to the top of the tree if the requested | |
199 | * id is larger than the currently allocated space. | |
200 | */ | |
589777ea | 201 | while ((layers < (MAX_LEVEL - 1)) && (id >= (1 << (layers*IDR_BITS)))) { |
1da177e4 LT |
202 | layers++; |
203 | if (!p->count) | |
204 | continue; | |
205 | if (!(new = alloc_layer(idp))) { | |
206 | /* | |
207 | * The allocation failed. If we built part of | |
208 | * the structure tear it down. | |
209 | */ | |
c259cc28 | 210 | spin_lock_irqsave(&idp->lock, flags); |
1da177e4 LT |
211 | for (new = p; p && p != idp->top; new = p) { |
212 | p = p->ary[0]; | |
213 | new->ary[0] = NULL; | |
214 | new->bitmap = new->count = 0; | |
1eec0056 | 215 | __free_layer(idp, new); |
1da177e4 | 216 | } |
c259cc28 | 217 | spin_unlock_irqrestore(&idp->lock, flags); |
1da177e4 LT |
218 | return -1; |
219 | } | |
220 | new->ary[0] = p; | |
221 | new->count = 1; | |
222 | if (p->bitmap == IDR_FULL) | |
223 | __set_bit(0, &new->bitmap); | |
224 | p = new; | |
225 | } | |
226 | idp->top = p; | |
227 | idp->layers = layers; | |
228 | v = sub_alloc(idp, ptr, &id); | |
229 | if (v == -2) | |
230 | goto build_up; | |
231 | return(v); | |
232 | } | |
233 | ||
234 | /** | |
7c657f2f | 235 | * idr_get_new_above - allocate new idr entry above or equal to a start id |
1da177e4 LT |
236 | * @idp: idr handle |
237 | * @ptr: pointer you want associated with the ide | |
238 | * @start_id: id to start search at | |
239 | * @id: pointer to the allocated handle | |
240 | * | |
241 | * This is the allocate id function. It should be called with any | |
242 | * required locks. | |
243 | * | |
244 | * If memory is required, it will return -EAGAIN, you should unlock | |
245 | * and go back to the idr_pre_get() call. If the idr is full, it will | |
246 | * return -ENOSPC. | |
247 | * | |
248 | * @id returns a value in the range 0 ... 0x7fffffff | |
249 | */ | |
250 | int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id) | |
251 | { | |
252 | int rv; | |
e15ae2dd | 253 | |
1da177e4 LT |
254 | rv = idr_get_new_above_int(idp, ptr, starting_id); |
255 | /* | |
256 | * This is a cheap hack until the IDR code can be fixed to | |
257 | * return proper error values. | |
258 | */ | |
259 | if (rv < 0) { | |
260 | if (rv == -1) | |
261 | return -EAGAIN; | |
262 | else /* Will be -3 */ | |
263 | return -ENOSPC; | |
264 | } | |
265 | *id = rv; | |
266 | return 0; | |
267 | } | |
268 | EXPORT_SYMBOL(idr_get_new_above); | |
269 | ||
270 | /** | |
271 | * idr_get_new - allocate new idr entry | |
272 | * @idp: idr handle | |
273 | * @ptr: pointer you want associated with the ide | |
274 | * @id: pointer to the allocated handle | |
275 | * | |
276 | * This is the allocate id function. It should be called with any | |
277 | * required locks. | |
278 | * | |
279 | * If memory is required, it will return -EAGAIN, you should unlock | |
280 | * and go back to the idr_pre_get() call. If the idr is full, it will | |
281 | * return -ENOSPC. | |
282 | * | |
283 | * @id returns a value in the range 0 ... 0x7fffffff | |
284 | */ | |
285 | int idr_get_new(struct idr *idp, void *ptr, int *id) | |
286 | { | |
287 | int rv; | |
e15ae2dd | 288 | |
1da177e4 LT |
289 | rv = idr_get_new_above_int(idp, ptr, 0); |
290 | /* | |
291 | * This is a cheap hack until the IDR code can be fixed to | |
292 | * return proper error values. | |
293 | */ | |
294 | if (rv < 0) { | |
295 | if (rv == -1) | |
296 | return -EAGAIN; | |
297 | else /* Will be -3 */ | |
298 | return -ENOSPC; | |
299 | } | |
300 | *id = rv; | |
301 | return 0; | |
302 | } | |
303 | EXPORT_SYMBOL(idr_get_new); | |
304 | ||
305 | static void idr_remove_warning(int id) | |
306 | { | |
307 | printk("idr_remove called for id=%d which is not allocated.\n", id); | |
308 | dump_stack(); | |
309 | } | |
310 | ||
311 | static void sub_remove(struct idr *idp, int shift, int id) | |
312 | { | |
313 | struct idr_layer *p = idp->top; | |
314 | struct idr_layer **pa[MAX_LEVEL]; | |
315 | struct idr_layer ***paa = &pa[0]; | |
316 | int n; | |
317 | ||
318 | *paa = NULL; | |
319 | *++paa = &idp->top; | |
320 | ||
321 | while ((shift > 0) && p) { | |
322 | n = (id >> shift) & IDR_MASK; | |
323 | __clear_bit(n, &p->bitmap); | |
324 | *++paa = &p->ary[n]; | |
325 | p = p->ary[n]; | |
326 | shift -= IDR_BITS; | |
327 | } | |
328 | n = id & IDR_MASK; | |
329 | if (likely(p != NULL && test_bit(n, &p->bitmap))){ | |
330 | __clear_bit(n, &p->bitmap); | |
331 | p->ary[n] = NULL; | |
332 | while(*paa && ! --((**paa)->count)){ | |
333 | free_layer(idp, **paa); | |
334 | **paa-- = NULL; | |
335 | } | |
e15ae2dd | 336 | if (!*paa) |
1da177e4 | 337 | idp->layers = 0; |
e15ae2dd | 338 | } else |
1da177e4 | 339 | idr_remove_warning(id); |
1da177e4 LT |
340 | } |
341 | ||
342 | /** | |
343 | * idr_remove - remove the given id and free it's slot | |
72fd4a35 RD |
344 | * @idp: idr handle |
345 | * @id: unique key | |
1da177e4 LT |
346 | */ |
347 | void idr_remove(struct idr *idp, int id) | |
348 | { | |
349 | struct idr_layer *p; | |
350 | ||
351 | /* Mask off upper bits we don't use for the search. */ | |
352 | id &= MAX_ID_MASK; | |
353 | ||
354 | sub_remove(idp, (idp->layers - 1) * IDR_BITS, id); | |
e15ae2dd JJ |
355 | if (idp->top && idp->top->count == 1 && (idp->layers > 1) && |
356 | idp->top->ary[0]) { // We can drop a layer | |
1da177e4 LT |
357 | |
358 | p = idp->top->ary[0]; | |
359 | idp->top->bitmap = idp->top->count = 0; | |
360 | free_layer(idp, idp->top); | |
361 | idp->top = p; | |
362 | --idp->layers; | |
363 | } | |
364 | while (idp->id_free_cnt >= IDR_FREE_MAX) { | |
1da177e4 LT |
365 | p = alloc_layer(idp); |
366 | kmem_cache_free(idr_layer_cache, p); | |
367 | return; | |
368 | } | |
369 | } | |
370 | EXPORT_SYMBOL(idr_remove); | |
371 | ||
8d3b3591 AM |
372 | /** |
373 | * idr_destroy - release all cached layers within an idr tree | |
374 | * idp: idr handle | |
375 | */ | |
376 | void idr_destroy(struct idr *idp) | |
377 | { | |
378 | while (idp->id_free_cnt) { | |
379 | struct idr_layer *p = alloc_layer(idp); | |
380 | kmem_cache_free(idr_layer_cache, p); | |
381 | } | |
382 | } | |
383 | EXPORT_SYMBOL(idr_destroy); | |
384 | ||
1da177e4 LT |
385 | /** |
386 | * idr_find - return pointer for given id | |
387 | * @idp: idr handle | |
388 | * @id: lookup key | |
389 | * | |
390 | * Return the pointer given the id it has been registered with. A %NULL | |
391 | * return indicates that @id is not valid or you passed %NULL in | |
392 | * idr_get_new(). | |
393 | * | |
394 | * The caller must serialize idr_find() vs idr_get_new() and idr_remove(). | |
395 | */ | |
396 | void *idr_find(struct idr *idp, int id) | |
397 | { | |
398 | int n; | |
399 | struct idr_layer *p; | |
400 | ||
401 | n = idp->layers * IDR_BITS; | |
402 | p = idp->top; | |
403 | ||
404 | /* Mask off upper bits we don't use for the search. */ | |
405 | id &= MAX_ID_MASK; | |
406 | ||
407 | if (id >= (1 << n)) | |
408 | return NULL; | |
409 | ||
410 | while (n > 0 && p) { | |
411 | n -= IDR_BITS; | |
412 | p = p->ary[(id >> n) & IDR_MASK]; | |
413 | } | |
414 | return((void *)p); | |
415 | } | |
416 | EXPORT_SYMBOL(idr_find); | |
417 | ||
5806f07c JM |
418 | /** |
419 | * idr_replace - replace pointer for given id | |
420 | * @idp: idr handle | |
421 | * @ptr: pointer you want associated with the id | |
422 | * @id: lookup key | |
423 | * | |
424 | * Replace the pointer registered with an id and return the old value. | |
425 | * A -ENOENT return indicates that @id was not found. | |
426 | * A -EINVAL return indicates that @id was not within valid constraints. | |
427 | * | |
428 | * The caller must serialize vs idr_find(), idr_get_new(), and idr_remove(). | |
429 | */ | |
430 | void *idr_replace(struct idr *idp, void *ptr, int id) | |
431 | { | |
432 | int n; | |
433 | struct idr_layer *p, *old_p; | |
434 | ||
435 | n = idp->layers * IDR_BITS; | |
436 | p = idp->top; | |
437 | ||
438 | id &= MAX_ID_MASK; | |
439 | ||
440 | if (id >= (1 << n)) | |
441 | return ERR_PTR(-EINVAL); | |
442 | ||
443 | n -= IDR_BITS; | |
444 | while ((n > 0) && p) { | |
445 | p = p->ary[(id >> n) & IDR_MASK]; | |
446 | n -= IDR_BITS; | |
447 | } | |
448 | ||
449 | n = id & IDR_MASK; | |
450 | if (unlikely(p == NULL || !test_bit(n, &p->bitmap))) | |
451 | return ERR_PTR(-ENOENT); | |
452 | ||
453 | old_p = p->ary[n]; | |
454 | p->ary[n] = ptr; | |
455 | ||
456 | return old_p; | |
457 | } | |
458 | EXPORT_SYMBOL(idr_replace); | |
459 | ||
e18b890b | 460 | static void idr_cache_ctor(void * idr_layer, struct kmem_cache *idr_layer_cache, |
e15ae2dd | 461 | unsigned long flags) |
1da177e4 LT |
462 | { |
463 | memset(idr_layer, 0, sizeof(struct idr_layer)); | |
464 | } | |
465 | ||
466 | static int init_id_cache(void) | |
467 | { | |
468 | if (!idr_layer_cache) | |
e15ae2dd | 469 | idr_layer_cache = kmem_cache_create("idr_layer_cache", |
1da177e4 LT |
470 | sizeof(struct idr_layer), 0, 0, idr_cache_ctor, NULL); |
471 | return 0; | |
472 | } | |
473 | ||
474 | /** | |
475 | * idr_init - initialize idr handle | |
476 | * @idp: idr handle | |
477 | * | |
478 | * This function is use to set up the handle (@idp) that you will pass | |
479 | * to the rest of the functions. | |
480 | */ | |
481 | void idr_init(struct idr *idp) | |
482 | { | |
483 | init_id_cache(); | |
484 | memset(idp, 0, sizeof(struct idr)); | |
485 | spin_lock_init(&idp->lock); | |
486 | } | |
487 | EXPORT_SYMBOL(idr_init); |