Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/lib/idr.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 3 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 3 months ago) by niro
File MIME type: text/plain
File size: 9578 byte(s)
Tag kernel26-2.6.12-alx-r9
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 | * Small id to pointer translation service. |
10 | * |
11 | * It uses a radix tree like structure as a sparse array indexed |
12 | * by the id to obtain the pointer. The bitmap makes allocating |
13 | * a new id quick. |
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 | |
20 | * You can release ids at any time. When all ids are released, most of |
21 | * the memory is returned (we keep IDR_FREE_MAX) in a local pool so we |
22 | * don't need to go to the memory "store" during an id allocate, just |
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 |
32 | #include <linux/string.h> |
33 | #include <linux/idr.h> |
34 | |
35 | static kmem_cache_t *idr_layer_cache; |
36 | |
37 | static struct idr_layer *alloc_layer(struct idr *idp) |
38 | { |
39 | struct idr_layer *p; |
40 | |
41 | spin_lock(&idp->lock); |
42 | if ((p = idp->id_free)) { |
43 | idp->id_free = p->ary[0]; |
44 | idp->id_free_cnt--; |
45 | p->ary[0] = NULL; |
46 | } |
47 | spin_unlock(&idp->lock); |
48 | return(p); |
49 | } |
50 | |
51 | static void free_layer(struct idr *idp, struct idr_layer *p) |
52 | { |
53 | /* |
54 | * Depends on the return element being zeroed. |
55 | */ |
56 | spin_lock(&idp->lock); |
57 | p->ary[0] = idp->id_free; |
58 | idp->id_free = p; |
59 | idp->id_free_cnt++; |
60 | spin_unlock(&idp->lock); |
61 | } |
62 | |
63 | /** |
64 | * idr_pre_get - reserver resources for idr allocation |
65 | * @idp: idr handle |
66 | * @gfp_mask: memory allocation flags |
67 | * |
68 | * This function should be called prior to locking and calling the |
69 | * following function. It preallocates enough memory to satisfy |
70 | * the worst possible allocation. |
71 | * |
72 | * If the system is REALLY out of memory this function returns 0, |
73 | * otherwise 1. |
74 | */ |
75 | int idr_pre_get(struct idr *idp, unsigned gfp_mask) |
76 | { |
77 | while (idp->id_free_cnt < IDR_FREE_MAX) { |
78 | struct idr_layer *new; |
79 | new = kmem_cache_alloc(idr_layer_cache, gfp_mask); |
80 | if(new == NULL) |
81 | return (0); |
82 | free_layer(idp, new); |
83 | } |
84 | return 1; |
85 | } |
86 | EXPORT_SYMBOL(idr_pre_get); |
87 | |
88 | static int sub_alloc(struct idr *idp, void *ptr, int *starting_id) |
89 | { |
90 | int n, m, sh; |
91 | struct idr_layer *p, *new; |
92 | struct idr_layer *pa[MAX_LEVEL]; |
93 | int l, id; |
94 | long bm; |
95 | |
96 | id = *starting_id; |
97 | p = idp->top; |
98 | l = idp->layers; |
99 | pa[l--] = NULL; |
100 | while (1) { |
101 | /* |
102 | * We run around this while until we reach the leaf node... |
103 | */ |
104 | n = (id >> (IDR_BITS*l)) & IDR_MASK; |
105 | bm = ~p->bitmap; |
106 | m = find_next_bit(&bm, IDR_SIZE, n); |
107 | if (m == IDR_SIZE) { |
108 | /* no space available go back to previous layer. */ |
109 | l++; |
110 | id = (id | ((1 << (IDR_BITS*l))-1)) + 1; |
111 | if (!(p = pa[l])) { |
112 | *starting_id = id; |
113 | return -2; |
114 | } |
115 | continue; |
116 | } |
117 | if (m != n) { |
118 | sh = IDR_BITS*l; |
119 | id = ((id >> sh) ^ n ^ m) << sh; |
120 | } |
121 | if ((id >= MAX_ID_BIT) || (id < 0)) |
122 | return -3; |
123 | if (l == 0) |
124 | break; |
125 | /* |
126 | * Create the layer below if it is missing. |
127 | */ |
128 | if (!p->ary[m]) { |
129 | if (!(new = alloc_layer(idp))) |
130 | return -1; |
131 | p->ary[m] = new; |
132 | p->count++; |
133 | } |
134 | pa[l--] = p; |
135 | p = p->ary[m]; |
136 | } |
137 | /* |
138 | * We have reached the leaf node, plant the |
139 | * users pointer and return the raw id. |
140 | */ |
141 | p->ary[m] = (struct idr_layer *)ptr; |
142 | __set_bit(m, &p->bitmap); |
143 | p->count++; |
144 | /* |
145 | * If this layer is full mark the bit in the layer above |
146 | * to show that this part of the radix tree is full. |
147 | * This may complete the layer above and require walking |
148 | * up the radix tree. |
149 | */ |
150 | n = id; |
151 | while (p->bitmap == IDR_FULL) { |
152 | if (!(p = pa[++l])) |
153 | break; |
154 | n = n >> IDR_BITS; |
155 | __set_bit((n & IDR_MASK), &p->bitmap); |
156 | } |
157 | return(id); |
158 | } |
159 | |
160 | static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id) |
161 | { |
162 | struct idr_layer *p, *new; |
163 | int layers, v, id; |
164 | |
165 | id = starting_id; |
166 | build_up: |
167 | p = idp->top; |
168 | layers = idp->layers; |
169 | if (unlikely(!p)) { |
170 | if (!(p = alloc_layer(idp))) |
171 | return -1; |
172 | layers = 1; |
173 | } |
174 | /* |
175 | * Add a new layer to the top of the tree if the requested |
176 | * id is larger than the currently allocated space. |
177 | */ |
178 | while ((layers < MAX_LEVEL) && (id >= (1 << (layers*IDR_BITS)))) { |
179 | layers++; |
180 | if (!p->count) |
181 | continue; |
182 | if (!(new = alloc_layer(idp))) { |
183 | /* |
184 | * The allocation failed. If we built part of |
185 | * the structure tear it down. |
186 | */ |
187 | for (new = p; p && p != idp->top; new = p) { |
188 | p = p->ary[0]; |
189 | new->ary[0] = NULL; |
190 | new->bitmap = new->count = 0; |
191 | free_layer(idp, new); |
192 | } |
193 | return -1; |
194 | } |
195 | new->ary[0] = p; |
196 | new->count = 1; |
197 | if (p->bitmap == IDR_FULL) |
198 | __set_bit(0, &new->bitmap); |
199 | p = new; |
200 | } |
201 | idp->top = p; |
202 | idp->layers = layers; |
203 | v = sub_alloc(idp, ptr, &id); |
204 | if (v == -2) |
205 | goto build_up; |
206 | return(v); |
207 | } |
208 | |
209 | /** |
210 | * idr_get_new_above - allocate new idr entry above a start id |
211 | * @idp: idr handle |
212 | * @ptr: pointer you want associated with the ide |
213 | * @start_id: id to start search at |
214 | * @id: pointer to the allocated handle |
215 | * |
216 | * This is the allocate id function. It should be called with any |
217 | * required locks. |
218 | * |
219 | * If memory is required, it will return -EAGAIN, you should unlock |
220 | * and go back to the idr_pre_get() call. If the idr is full, it will |
221 | * return -ENOSPC. |
222 | * |
223 | * @id returns a value in the range 0 ... 0x7fffffff |
224 | */ |
225 | int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id) |
226 | { |
227 | int rv; |
228 | rv = idr_get_new_above_int(idp, ptr, starting_id); |
229 | /* |
230 | * This is a cheap hack until the IDR code can be fixed to |
231 | * return proper error values. |
232 | */ |
233 | if (rv < 0) { |
234 | if (rv == -1) |
235 | return -EAGAIN; |
236 | else /* Will be -3 */ |
237 | return -ENOSPC; |
238 | } |
239 | *id = rv; |
240 | return 0; |
241 | } |
242 | EXPORT_SYMBOL(idr_get_new_above); |
243 | |
244 | /** |
245 | * idr_get_new - allocate new idr entry |
246 | * @idp: idr handle |
247 | * @ptr: pointer you want associated with the ide |
248 | * @id: pointer to the allocated handle |
249 | * |
250 | * This is the allocate id function. It should be called with any |
251 | * required locks. |
252 | * |
253 | * If memory is required, it will return -EAGAIN, you should unlock |
254 | * and go back to the idr_pre_get() call. If the idr is full, it will |
255 | * return -ENOSPC. |
256 | * |
257 | * @id returns a value in the range 0 ... 0x7fffffff |
258 | */ |
259 | int idr_get_new(struct idr *idp, void *ptr, int *id) |
260 | { |
261 | int rv; |
262 | rv = idr_get_new_above_int(idp, ptr, 0); |
263 | /* |
264 | * This is a cheap hack until the IDR code can be fixed to |
265 | * return proper error values. |
266 | */ |
267 | if (rv < 0) { |
268 | if (rv == -1) |
269 | return -EAGAIN; |
270 | else /* Will be -3 */ |
271 | return -ENOSPC; |
272 | } |
273 | *id = rv; |
274 | return 0; |
275 | } |
276 | EXPORT_SYMBOL(idr_get_new); |
277 | |
278 | static void idr_remove_warning(int id) |
279 | { |
280 | printk("idr_remove called for id=%d which is not allocated.\n", id); |
281 | dump_stack(); |
282 | } |
283 | |
284 | static void sub_remove(struct idr *idp, int shift, int id) |
285 | { |
286 | struct idr_layer *p = idp->top; |
287 | struct idr_layer **pa[MAX_LEVEL]; |
288 | struct idr_layer ***paa = &pa[0]; |
289 | int n; |
290 | |
291 | *paa = NULL; |
292 | *++paa = &idp->top; |
293 | |
294 | while ((shift > 0) && p) { |
295 | n = (id >> shift) & IDR_MASK; |
296 | __clear_bit(n, &p->bitmap); |
297 | *++paa = &p->ary[n]; |
298 | p = p->ary[n]; |
299 | shift -= IDR_BITS; |
300 | } |
301 | n = id & IDR_MASK; |
302 | if (likely(p != NULL && test_bit(n, &p->bitmap))){ |
303 | __clear_bit(n, &p->bitmap); |
304 | p->ary[n] = NULL; |
305 | while(*paa && ! --((**paa)->count)){ |
306 | free_layer(idp, **paa); |
307 | **paa-- = NULL; |
308 | } |
309 | if ( ! *paa ) |
310 | idp->layers = 0; |
311 | } else { |
312 | idr_remove_warning(id); |
313 | } |
314 | } |
315 | |
316 | /** |
317 | * idr_remove - remove the given id and free it's slot |
318 | * idp: idr handle |
319 | * id: uniqueue key |
320 | */ |
321 | void idr_remove(struct idr *idp, int id) |
322 | { |
323 | struct idr_layer *p; |
324 | |
325 | /* Mask off upper bits we don't use for the search. */ |
326 | id &= MAX_ID_MASK; |
327 | |
328 | sub_remove(idp, (idp->layers - 1) * IDR_BITS, id); |
329 | if ( idp->top && idp->top->count == 1 && |
330 | (idp->layers > 1) && |
331 | idp->top->ary[0]){ // We can drop a layer |
332 | |
333 | p = idp->top->ary[0]; |
334 | idp->top->bitmap = idp->top->count = 0; |
335 | free_layer(idp, idp->top); |
336 | idp->top = p; |
337 | --idp->layers; |
338 | } |
339 | while (idp->id_free_cnt >= IDR_FREE_MAX) { |
340 | |
341 | p = alloc_layer(idp); |
342 | kmem_cache_free(idr_layer_cache, p); |
343 | return; |
344 | } |
345 | } |
346 | EXPORT_SYMBOL(idr_remove); |
347 | |
348 | /** |
349 | * idr_find - return pointer for given id |
350 | * @idp: idr handle |
351 | * @id: lookup key |
352 | * |
353 | * Return the pointer given the id it has been registered with. A %NULL |
354 | * return indicates that @id is not valid or you passed %NULL in |
355 | * idr_get_new(). |
356 | * |
357 | * The caller must serialize idr_find() vs idr_get_new() and idr_remove(). |
358 | */ |
359 | void *idr_find(struct idr *idp, int id) |
360 | { |
361 | int n; |
362 | struct idr_layer *p; |
363 | |
364 | n = idp->layers * IDR_BITS; |
365 | p = idp->top; |
366 | |
367 | /* Mask off upper bits we don't use for the search. */ |
368 | id &= MAX_ID_MASK; |
369 | |
370 | if (id >= (1 << n)) |
371 | return NULL; |
372 | |
373 | while (n > 0 && p) { |
374 | n -= IDR_BITS; |
375 | p = p->ary[(id >> n) & IDR_MASK]; |
376 | } |
377 | return((void *)p); |
378 | } |
379 | EXPORT_SYMBOL(idr_find); |
380 | |
381 | static void idr_cache_ctor(void * idr_layer, |
382 | kmem_cache_t *idr_layer_cache, unsigned long flags) |
383 | { |
384 | memset(idr_layer, 0, sizeof(struct idr_layer)); |
385 | } |
386 | |
387 | static int init_id_cache(void) |
388 | { |
389 | if (!idr_layer_cache) |
390 | idr_layer_cache = kmem_cache_create("idr_layer_cache", |
391 | sizeof(struct idr_layer), 0, 0, idr_cache_ctor, NULL); |
392 | return 0; |
393 | } |
394 | |
395 | /** |
396 | * idr_init - initialize idr handle |
397 | * @idp: idr handle |
398 | * |
399 | * This function is use to set up the handle (@idp) that you will pass |
400 | * to the rest of the functions. |
401 | */ |
402 | void idr_init(struct idr *idp) |
403 | { |
404 | init_id_cache(); |
405 | memset(idp, 0, sizeof(struct idr)); |
406 | spin_lock_init(&idp->lock); |
407 | } |
408 | EXPORT_SYMBOL(idr_init); |