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acddc0ed | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
a94eca09 MS |
2 | /* |
3 | * FRR ID Number Allocator | |
4 | * Copyright (C) 2018 Amazon.com, Inc. or its affiliates | |
a94eca09 MS |
5 | */ |
6 | ||
2618a52e DL |
7 | #ifdef HAVE_CONFIG_H |
8 | #include "config.h" | |
9 | #endif | |
10 | ||
a94eca09 MS |
11 | #include "id_alloc.h" |
12 | ||
13 | #include "log.h" | |
14 | #include "lib_errors.h" | |
15 | #include "memory.h" | |
16 | ||
17 | #include <inttypes.h> | |
18 | ||
bf8d3d6a DL |
19 | DEFINE_MTYPE_STATIC(LIB, IDALLOC_ALLOCATOR, "ID Number Allocator"); |
20 | DEFINE_MTYPE_STATIC(LIB, IDALLOC_ALLOCATOR_NAME, "ID Number Allocator Name"); | |
21 | DEFINE_MTYPE_STATIC(LIB, IDALLOC_DIRECTORY, "ID Number Allocator Directory"); | |
a94eca09 | 22 | DEFINE_MTYPE_STATIC(LIB, IDALLOC_SUBDIRECTORY, |
bf8d3d6a DL |
23 | "ID Number Allocator Subdirectory"); |
24 | DEFINE_MTYPE_STATIC(LIB, IDALLOC_PAGE, "ID Number Allocator Page"); | |
25 | DEFINE_MTYPE_STATIC(LIB, IDALLOC_POOL, | |
26 | "ID Number temporary holding pool entry"); | |
a94eca09 MS |
27 | |
28 | #if UINT_MAX >= UINT32_MAX | |
29 | #define FFS32(x) ffs(x) | |
30 | #else | |
31 | /* ints less than 32 bits? Yikes. */ | |
32 | #define FFS32(x) ffsl(x) | |
33 | #endif | |
34 | ||
35 | #define DIR_MASK ((1<<IDALLOC_DIR_BITS)-1) | |
36 | #define SUBDIR_MASK ((1<<IDALLOC_SUBDIR_BITS)-1) | |
4a600b08 | 37 | #define FRR_ID_PAGE_MASK ((1<<IDALLOC_PAGE_BITS)-1) |
a94eca09 MS |
38 | #define WORD_MASK ((1<<IDALLOC_WORD_BITS)-1) |
39 | #define OFFSET_MASK ((1<<IDALLOC_OFFSET_BITS)-1) | |
40 | ||
41 | #define DIR_SHIFT (IDALLOC_OFFSET_BITS + IDALLOC_WORD_BITS + \ | |
42 | IDALLOC_PAGE_BITS + IDALLOC_SUBDIR_BITS) | |
43 | #define SUBDIR_SHIFT (IDALLOC_OFFSET_BITS + IDALLOC_WORD_BITS + \ | |
44 | IDALLOC_PAGE_BITS) | |
4a600b08 | 45 | #define FRR_ID_PAGE_SHIFT (IDALLOC_OFFSET_BITS + IDALLOC_WORD_BITS) |
a94eca09 MS |
46 | #define WORD_SHIFT (IDALLOC_OFFSET_BITS) |
47 | #define OFFSET_SHIFT (0) | |
48 | ||
49 | #define ID_DIR(id) ((id >> DIR_SHIFT) & DIR_MASK) | |
50 | #define ID_SUBDIR(id) ((id >> SUBDIR_SHIFT) & SUBDIR_MASK) | |
4a600b08 | 51 | #define ID_PAGE(id) ((id >> FRR_ID_PAGE_SHIFT) & FRR_ID_PAGE_MASK) |
a94eca09 MS |
52 | #define ID_WORD(id) ((id >> WORD_SHIFT) & WORD_MASK) |
53 | #define ID_OFFSET(id) ((id >> OFFSET_SHIFT) & OFFSET_MASK) | |
54 | ||
55 | /* | |
56 | * Find the page that an ID number belongs to in an allocator. | |
57 | * Optionally create the page if it doesn't exist. | |
58 | */ | |
59 | static struct id_alloc_page *find_or_create_page(struct id_alloc *alloc, | |
60 | uint32_t id, int create) | |
61 | { | |
62 | struct id_alloc_dir *dir = NULL; | |
63 | struct id_alloc_subdir *subdir = NULL; | |
64 | struct id_alloc_page *page = NULL; | |
65 | ||
66 | dir = alloc->sublevels[ID_DIR(id)]; | |
67 | if (dir == NULL) { | |
68 | if (create) { | |
69 | dir = XCALLOC(MTYPE_IDALLOC_DIRECTORY, sizeof(*dir)); | |
70 | alloc->sublevels[ID_DIR(id)] = dir; | |
71 | } else { | |
72 | return NULL; | |
73 | } | |
74 | } | |
75 | ||
76 | subdir = dir->sublevels[ID_SUBDIR(id)]; | |
77 | if (subdir == NULL) { | |
78 | if (create) { | |
79 | subdir = XCALLOC(MTYPE_IDALLOC_SUBDIRECTORY, | |
80 | sizeof(*subdir)); | |
81 | dir->sublevels[ID_SUBDIR(id)] = subdir; | |
82 | } else { | |
83 | return NULL; | |
84 | } | |
85 | } | |
86 | ||
87 | page = subdir->sublevels[ID_PAGE(id)]; | |
88 | if (page == NULL && create) { | |
89 | page = XCALLOC(MTYPE_IDALLOC_PAGE, sizeof(*page)); | |
90 | page->base_value = id; | |
91 | subdir->sublevels[ID_PAGE(id)] = page; | |
92 | ||
4a600b08 | 93 | alloc->capacity += 1 << FRR_ID_PAGE_SHIFT; |
a94eca09 MS |
94 | page->next_has_free = alloc->has_free; |
95 | alloc->has_free = page; | |
96 | } else if (page != NULL && create) { | |
97 | flog_err( | |
98 | EC_LIB_ID_CONSISTENCY, | |
6cde4b45 | 99 | "ID Allocator %s attempt to re-create page at %u", |
a94eca09 MS |
100 | alloc->name, id); |
101 | } | |
102 | ||
103 | return page; | |
104 | } | |
105 | ||
106 | /* | |
107 | * Return an ID number back to the allocator. | |
108 | * While this ID can be re-assigned through idalloc_allocate, the underlying | |
109 | * memory will not be freed. If this is the first free ID in the page, the page | |
110 | * will be added to the allocator's list of pages with free IDs. | |
111 | */ | |
112 | void idalloc_free(struct id_alloc *alloc, uint32_t id) | |
113 | { | |
114 | struct id_alloc_page *page = NULL; | |
115 | ||
116 | int word, offset; | |
117 | uint32_t old_word, old_word_mask; | |
118 | ||
119 | page = find_or_create_page(alloc, id, 0); | |
120 | if (!page) { | |
121 | flog_err(EC_LIB_ID_CONSISTENCY, | |
6cde4b45 | 122 | "ID Allocator %s cannot free #%u. ID Block does not exist.", |
a94eca09 MS |
123 | alloc->name, id); |
124 | return; | |
125 | } | |
126 | ||
127 | word = ID_WORD(id); | |
128 | offset = ID_OFFSET(id); | |
129 | ||
130 | if ((page->allocated_mask[word] & (1 << offset)) == 0) { | |
131 | flog_err(EC_LIB_ID_CONSISTENCY, | |
6cde4b45 | 132 | "ID Allocator %s cannot free #%u. ID was not allocated at the time of free.", |
a94eca09 MS |
133 | alloc->name, id); |
134 | return; | |
135 | } | |
136 | ||
137 | old_word = page->allocated_mask[word]; | |
138 | page->allocated_mask[word] &= ~(((uint32_t)1) << offset); | |
139 | alloc->allocated -= 1; | |
140 | ||
141 | if (old_word == UINT32_MAX) { | |
142 | /* first bit in this block of 32 to be freed.*/ | |
143 | ||
144 | old_word_mask = page->full_word_mask; | |
145 | page->full_word_mask &= ~(((uint32_t)1) << word); | |
146 | ||
147 | if (old_word_mask == UINT32_MAX) { | |
148 | /* first bit in page freed, add this to the allocator's | |
149 | * list of pages with free space | |
150 | */ | |
151 | page->next_has_free = alloc->has_free; | |
152 | alloc->has_free = page; | |
153 | } | |
154 | } | |
155 | } | |
156 | ||
157 | /* | |
158 | * Add a allocation page to the end of the allocator's current range. | |
159 | * Returns null if the allocator has had all possible pages allocated already. | |
160 | */ | |
161 | static struct id_alloc_page *create_next_page(struct id_alloc *alloc) | |
162 | { | |
163 | if (alloc->capacity == 0 && alloc->sublevels[0]) | |
164 | return NULL; /* All IDs allocated and the capacity looped. */ | |
165 | ||
166 | return find_or_create_page(alloc, alloc->capacity, 1); | |
167 | } | |
168 | ||
169 | /* | |
170 | * Marks an ID within an allocator page as in use. | |
171 | * If the ID was the last free ID in the page, the page is removed from the | |
172 | * allocator's list of free IDs. In the typical allocation case, this page is | |
173 | * the first page in the list, and removing the page is fast. If instead an ID | |
174 | * is being reserved by number, this may end up scanning the whole single linked | |
175 | * list of pages in order to remove it. | |
176 | */ | |
177 | static void reserve_bit(struct id_alloc *alloc, struct id_alloc_page *page, | |
178 | int word, int offset) | |
179 | { | |
180 | struct id_alloc_page *itr; | |
181 | ||
182 | page->allocated_mask[word] |= ((uint32_t)1) << offset; | |
183 | alloc->allocated += 1; | |
184 | ||
185 | if (page->allocated_mask[word] == UINT32_MAX) { | |
186 | page->full_word_mask |= ((uint32_t)1) << word; | |
187 | if (page->full_word_mask == UINT32_MAX) { | |
188 | if (alloc->has_free == page) { | |
189 | /* allocate always pulls from alloc->has_free */ | |
190 | alloc->has_free = page->next_has_free; | |
191 | } else { | |
192 | /* reserve could pull from any page with free | |
193 | * bits | |
194 | */ | |
195 | itr = alloc->has_free; | |
196 | while (itr) { | |
197 | if (itr->next_has_free == page) { | |
198 | itr->next_has_free = | |
199 | page->next_has_free; | |
200 | return; | |
201 | } | |
202 | ||
203 | itr = itr->next_has_free; | |
204 | } | |
205 | } | |
206 | } | |
207 | } | |
208 | } | |
209 | ||
210 | /* | |
211 | * Reserve an ID number from the allocator. Returns IDALLOC_INVALID (0) if the | |
212 | * allocator has no more IDs available. | |
213 | */ | |
214 | uint32_t idalloc_allocate(struct id_alloc *alloc) | |
215 | { | |
216 | struct id_alloc_page *page; | |
217 | int word, offset; | |
218 | uint32_t return_value; | |
219 | ||
220 | if (alloc->has_free == NULL) | |
221 | create_next_page(alloc); | |
222 | ||
223 | if (alloc->has_free == NULL) { | |
224 | flog_err(EC_LIB_ID_EXHAUST, | |
225 | "ID Allocator %s has run out of IDs.", alloc->name); | |
226 | return IDALLOC_INVALID; | |
227 | } | |
228 | ||
229 | page = alloc->has_free; | |
230 | word = FFS32(~(page->full_word_mask)) - 1; | |
231 | ||
232 | if (word < 0 || word >= 32) { | |
233 | flog_err(EC_LIB_ID_CONSISTENCY, | |
234 | "ID Allocator %s internal error. Page starting at %d is inconsistent.", | |
235 | alloc->name, page->base_value); | |
236 | return IDALLOC_INVALID; | |
237 | } | |
238 | ||
239 | offset = FFS32(~(page->allocated_mask[word])) - 1; | |
240 | if (offset < 0 || offset >= 32) { | |
241 | flog_err(EC_LIB_ID_CONSISTENCY, | |
242 | "ID Allocator %s internal error. Page starting at %d is inconsistent on word %d", | |
243 | alloc->name, page->base_value, word); | |
244 | return IDALLOC_INVALID; | |
245 | } | |
246 | return_value = page->base_value + word * 32 + offset; | |
247 | ||
248 | reserve_bit(alloc, page, word, offset); | |
249 | ||
250 | return return_value; | |
251 | } | |
252 | ||
253 | /* | |
254 | * Tries to allocate a specific ID from the allocator. Returns IDALLOC_INVALID | |
255 | * when the ID being "reserved" has allready been assigned/reserved. This should | |
256 | * only be done with low numbered IDs, as the allocator needs to reserve bit-map | |
257 | * pages in order | |
258 | */ | |
259 | uint32_t idalloc_reserve(struct id_alloc *alloc, uint32_t id) | |
260 | { | |
261 | struct id_alloc_page *page; | |
262 | int word, offset; | |
263 | ||
264 | while (alloc->capacity <= id) | |
265 | create_next_page(alloc); | |
266 | ||
267 | word = ID_WORD(id); | |
268 | offset = ID_OFFSET(id); | |
269 | page = find_or_create_page(alloc, id, 0); | |
270 | /* page can't be null because the loop above ensured it was created. */ | |
271 | ||
272 | if (page->allocated_mask[word] & (((uint32_t)1) << offset)) { | |
273 | flog_err(EC_LIB_ID_CONSISTENCY, | |
6cde4b45 | 274 | "ID Allocator %s could not reserve %u because it is already allocated.", |
a94eca09 MS |
275 | alloc->name, id); |
276 | return IDALLOC_INVALID; | |
277 | } | |
278 | ||
279 | reserve_bit(alloc, page, word, offset); | |
280 | return id; | |
281 | } | |
282 | ||
283 | /* | |
284 | * Set up an empty ID allocator, with IDALLOC_INVALID pre-reserved. | |
285 | */ | |
286 | struct id_alloc *idalloc_new(const char *name) | |
287 | { | |
288 | struct id_alloc *ret; | |
289 | ||
290 | ret = XCALLOC(MTYPE_IDALLOC_ALLOCATOR, sizeof(*ret)); | |
291 | ret->name = XSTRDUP(MTYPE_IDALLOC_ALLOCATOR_NAME, name); | |
292 | ||
293 | idalloc_reserve(ret, IDALLOC_INVALID); | |
294 | ||
295 | return ret; | |
296 | } | |
297 | ||
298 | /* | |
299 | * Free a subdir, and all pages below it. | |
300 | */ | |
301 | static void idalloc_destroy_subdir(struct id_alloc_subdir *subdir) | |
302 | { | |
303 | int i; | |
304 | ||
305 | for (i = 0; i < IDALLOC_PAGE_COUNT; i++) { | |
306 | if (subdir->sublevels[i]) | |
307 | XFREE(MTYPE_IDALLOC_PAGE, subdir->sublevels[i]); | |
308 | else | |
309 | break; | |
310 | } | |
311 | XFREE(MTYPE_IDALLOC_SUBDIRECTORY, subdir); | |
312 | } | |
313 | ||
314 | /* | |
315 | * Free a dir, and all subdirs/pages below it. | |
316 | */ | |
317 | static void idalloc_destroy_dir(struct id_alloc_dir *dir) | |
318 | { | |
319 | int i; | |
320 | ||
321 | for (i = 0; i < IDALLOC_SUBDIR_COUNT; i++) { | |
322 | if (dir->sublevels[i]) | |
323 | idalloc_destroy_subdir(dir->sublevels[i]); | |
324 | else | |
325 | break; | |
326 | } | |
327 | XFREE(MTYPE_IDALLOC_DIRECTORY, dir); | |
328 | } | |
329 | ||
330 | /* | |
331 | * Free all memory associated with an ID allocator. | |
332 | */ | |
333 | void idalloc_destroy(struct id_alloc *alloc) | |
334 | { | |
335 | int i; | |
336 | ||
337 | for (i = 0; i < IDALLOC_DIR_COUNT; i++) { | |
338 | if (alloc->sublevels[i]) | |
339 | idalloc_destroy_dir(alloc->sublevels[i]); | |
340 | else | |
341 | break; | |
342 | } | |
343 | ||
344 | XFREE(MTYPE_IDALLOC_ALLOCATOR_NAME, alloc->name); | |
345 | XFREE(MTYPE_IDALLOC_ALLOCATOR, alloc); | |
346 | } | |
347 | ||
348 | /* | |
349 | * Give an ID number to temporary holding pool. | |
350 | */ | |
351 | void idalloc_free_to_pool(struct id_alloc_pool **pool_ptr, uint32_t id) | |
352 | { | |
353 | struct id_alloc_pool *new_pool; | |
354 | ||
355 | new_pool = XMALLOC(MTYPE_IDALLOC_POOL, sizeof(*new_pool)); | |
356 | new_pool->id = id; | |
357 | new_pool->next = *pool_ptr; | |
358 | *pool_ptr = new_pool; | |
359 | } | |
360 | ||
361 | /* | |
362 | * Free all ID numbers held in a holding pool back to the main allocator. | |
363 | */ | |
364 | void idalloc_drain_pool(struct id_alloc *alloc, struct id_alloc_pool **pool_ptr) | |
365 | { | |
366 | struct id_alloc_pool *current, *next; | |
367 | ||
368 | while (*pool_ptr) { | |
369 | current = *pool_ptr; | |
370 | next = current->next; | |
371 | idalloc_free(alloc, current->id); | |
372 | XFREE(MTYPE_IDALLOC_POOL, current); | |
373 | *pool_ptr = next; | |
374 | } | |
375 | } | |
376 | ||
377 | /* | |
378 | * Allocate an ID from either a holding pool, or the main allocator. IDs will | |
379 | * only be pulled form the main allocator when the pool is empty. | |
380 | */ | |
381 | uint32_t idalloc_allocate_prefer_pool(struct id_alloc *alloc, | |
382 | struct id_alloc_pool **pool_ptr) | |
383 | { | |
384 | uint32_t ret; | |
385 | struct id_alloc_pool *pool_head = *pool_ptr; | |
386 | ||
387 | if (pool_head) { | |
388 | ret = pool_head->id; | |
389 | *pool_ptr = pool_head->next; | |
390 | XFREE(MTYPE_IDALLOC_POOL, pool_head); | |
391 | return ret; | |
392 | } else { | |
393 | return idalloc_allocate(alloc); | |
394 | } | |
395 | } |