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1 | /* |
2 | * rcuja/rcuja-range.c | |
3 | * | |
4 | * Userspace RCU library - RCU Judy Array Range Support | |
5 | * | |
6 | * Copyright 2012-2013 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
7 | * | |
8 | * This library is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU Lesser General Public | |
10 | * License as published by the Free Software Foundation; either | |
11 | * version 2.1 of the License, or (at your option) any later version. | |
12 | * | |
13 | * This library is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | * Lesser General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU Lesser General Public | |
19 | * License along with this library; if not, write to the Free Software | |
20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
21 | */ | |
22 | ||
23 | #define _LGPL_SOURCE | |
24 | #include <stdint.h> | |
25 | #include <errno.h> | |
26 | #include <limits.h> | |
27 | #include <string.h> | |
28 | #include <assert.h> | |
29 | #include <pthread.h> | |
30 | #include <urcu/rcuja.h> | |
31 | #include <urcu/compiler.h> | |
32 | #include <urcu/arch.h> | |
33 | #include <urcu-pointer.h> | |
34 | #include <urcu/uatomic.h> | |
35 | #include <urcu/rcuja-range.h> | |
36 | #include <urcu-flavor.h> | |
37 | ||
38 | #include "rcuja-internal.h" | |
39 | ||
40 | /* | |
41 | * Discussion about order of lookup/lock vs allocated node deletion. | |
42 | * | |
43 | * - If node deletion returns before call to | |
44 | * cds_ja_range_lookup(), the node will not be found by lookup. | |
45 | * - If node deletion is called after cds_ja_range_lock() returns a | |
46 | * non-NULL range, the deletion will wait until the lock is released | |
47 | * before it takes place. | |
48 | * - If node deletion call/return overlaps with the call to | |
49 | * cds_ja_range_lookup() and return from cds_ja_range_lock(), the node | |
50 | * may or may not be found by each of cds_ja_range_lookup() and | |
51 | * cds_ja_range_lock(). | |
52 | */ | |
53 | ||
54 | /* | |
55 | * Discussion about order of lookup/lock vs allocated node add. Assuming | |
56 | * no concurrent delete. | |
57 | * | |
58 | * - If node add returns before call to | |
59 | * cds_ja_range_lookup(), the node will be found by lookup. | |
60 | * - If node add is called after cds_ja_range_lookup returns, the node | |
61 | * will not be found by lookup. | |
62 | * - If node add call/return overlaps with the call to and return from | |
63 | * cds_ja_range_lookup(), the node may or may not be found. | |
64 | * - If node add call/return overlaps with call to cds_ja_range_lookup() | |
65 | * and return from cds_ja_range_lock(), in the specific case where | |
66 | * cds_ja_range_lookup() _does_ succeed, then cds_ja_range_lock() will | |
67 | * succeed (still assuming no concurrent deletion). | |
68 | */ | |
69 | ||
70 | /* | |
71 | * Discussion of the type state transitions. | |
72 | * | |
73 | * State transitions of "type" always go from either: | |
74 | * | |
75 | * CDS_JA_RANGE_FREE -> CDS_JA_RANGE_REMOVED | |
76 | * or | |
77 | * CDS_JA_RANGE_ALLOCATED -> CDS_JA_RANGE_REMOVED | |
78 | * | |
79 | * A range type never changes otherwise. | |
80 | */ | |
81 | ||
82 | ||
83 | struct cds_ja_range *cds_ja_range_lookup(struct cds_ja *ja, uint64_t key) | |
84 | { | |
85 | struct cds_ja_node *node, *last_node; | |
86 | struct cds_ja_range *range; | |
87 | ||
88 | node = cds_ja_lookup_below_equal(ja, key, NULL); | |
89 | assert(node); | |
90 | /* | |
91 | * Get the last of duplicate chain. Adding a node to Judy array | |
92 | * duplicates inserts them at the end of the chain. | |
93 | */ | |
94 | cds_ja_for_each_duplicate_rcu(node) | |
95 | last_node = node; | |
96 | range = caa_container_of(last_node, struct cds_ja_range, ja_node); | |
97 | /* | |
98 | * If last node in the duplicates is removed or free, we can | |
99 | * consider that either a removal or add operation is in | |
100 | * progress, or removal is the last completed operation to | |
101 | * update this range. We can therefore consider that this area | |
102 | * is not allocated. | |
103 | */ | |
104 | if (range->type != CDS_JA_RANGE_ALLOCATED) | |
105 | return NULL; | |
106 | /* | |
107 | * We found an allocated range. We can return it for use with | |
7c74dcc7 | 108 | * RCU read-side protection for existence. However, we have no |
b45a45b9 MD |
109 | * mutual exclusion against removal at this point. |
110 | */ | |
111 | return range; | |
112 | } | |
113 | ||
114 | /* | |
115 | * Provide mutual exclusion against removal. | |
116 | */ | |
117 | struct cds_ja_range *cds_ja_range_lock(struct cds_ja_range *range) | |
118 | { | |
119 | pthread_mutex_lock(&range->lock); | |
120 | ||
121 | if (range->type == CDS_JA_RANGE_REMOVED) | |
122 | goto removed; | |
123 | return range; | |
124 | ||
125 | removed: | |
126 | pthread_mutex_unlock(&range->lock); | |
127 | return NULL; | |
128 | } | |
129 | ||
130 | void cds_ja_range_unlock(struct cds_ja_range *range) | |
131 | { | |
132 | pthread_mutex_unlock(&range->lock); | |
133 | } | |
134 | ||
135 | static | |
136 | struct cds_ja_range *range_create( | |
137 | uint64_t start, /* inclusive */ | |
138 | uint64_t end, /* inclusive */ | |
139 | enum cds_ja_range_type type) | |
140 | { | |
141 | struct cds_ja_range *range; | |
142 | ||
143 | range = calloc(sizeof(*range), 1); | |
144 | if (!range) | |
145 | return NULL; | |
146 | range->start = start; | |
147 | range->end = end; | |
148 | range->type = type; | |
149 | pthread_mutex_init(&range->lock, NULL); | |
150 | return range; | |
151 | } | |
152 | ||
153 | static | |
154 | void free_range_cb(struct rcu_head *head) | |
155 | { | |
156 | struct cds_ja_range *range = | |
157 | caa_container_of(head, struct cds_ja_range, head); | |
158 | free(range); | |
159 | } | |
160 | ||
161 | static | |
162 | void free_range(struct cds_ja_range *range) | |
163 | { | |
164 | free(range); | |
165 | } | |
166 | ||
167 | static | |
168 | void rcu_free_range(struct cds_ja *ja, struct cds_ja_range *range) | |
169 | { | |
170 | cds_lfht_rcu_flavor(ja->ht)->update_call_rcu(&range->head, | |
171 | free_range_cb); | |
172 | } | |
173 | ||
174 | struct cds_ja_range *cds_ja_range_add(struct cds_ja *ja, | |
175 | uint64_t start, /* inclusive */ | |
176 | uint64_t end) /* inclusive */ | |
177 | { | |
178 | struct cds_ja_node *old_node, *old_node_end; | |
179 | struct cds_ja_range *old_range, *old_range_end, *new_range, *ranges[3]; | |
180 | unsigned int nr_ranges, i; | |
181 | int ret; | |
182 | ||
183 | retry: | |
184 | /* | |
185 | * Find if requested range is entirely contained within a single | |
186 | * free range. | |
187 | */ | |
188 | old_node = cds_ja_lookup_below_equal(ja, start, NULL); | |
189 | assert(old_node); | |
190 | ||
191 | old_range = caa_container_of(old_node, struct cds_ja_range, ja_node); | |
192 | switch (CMM_LOAD_SHARED(old_range->type)) { | |
193 | case CDS_JA_RANGE_ALLOCATED: | |
194 | return NULL; | |
195 | case CDS_JA_RANGE_FREE: | |
196 | break; | |
197 | case CDS_JA_RANGE_REMOVED: | |
198 | goto retry; | |
199 | } | |
200 | ||
201 | old_node_end = cds_ja_lookup_below_equal(ja, end, NULL); | |
202 | assert(old_node_end); | |
203 | old_range_end = caa_container_of(old_node_end, | |
204 | struct cds_ja_range, ja_node); | |
205 | if (old_range_end != old_range) { | |
206 | switch (CMM_LOAD_SHARED(old_range->type)) { | |
207 | case CDS_JA_RANGE_ALLOCATED: | |
208 | case CDS_JA_RANGE_FREE: /* fall-through */ | |
209 | /* | |
210 | * TODO: think about free range merge. | |
211 | */ | |
212 | return NULL; | |
213 | case CDS_JA_RANGE_REMOVED: | |
214 | goto retry; | |
215 | } | |
216 | } | |
217 | ||
218 | pthread_mutex_lock(&old_range->lock); | |
219 | ||
220 | if (old_range->type == CDS_JA_RANGE_REMOVED) { | |
221 | pthread_mutex_unlock(&old_range->lock); | |
222 | goto retry; | |
223 | } | |
224 | ||
225 | /* Create replacement ranges: at most 2 free and 1 allocated */ | |
226 | if (start == old_range->start) { | |
227 | if (end == old_range->end) { | |
228 | /* 1 range */ | |
229 | ranges[0] = new_range = range_create(start, end, | |
230 | CDS_JA_RANGE_ALLOCATED); | |
231 | nr_ranges = 1; | |
232 | } else { | |
233 | /* 2 ranges */ | |
234 | ranges[0] = new_range = range_create(start, end, | |
235 | CDS_JA_RANGE_ALLOCATED); | |
236 | ranges[1] = range_create(end + 1, old_range->end, | |
237 | CDS_JA_RANGE_FREE); | |
238 | nr_ranges = 2; | |
239 | } | |
240 | } else { | |
241 | if (end == old_range->end) { | |
242 | /* 2 ranges */ | |
243 | ranges[0] = range_create(old_range->start, start - 1, | |
244 | CDS_JA_RANGE_FREE); | |
245 | ranges[1] = new_range = range_create(start, end, | |
246 | CDS_JA_RANGE_ALLOCATED); | |
247 | nr_ranges = 2; | |
248 | } else { | |
249 | /* 3 ranges */ | |
250 | ranges[0] = range_create(old_range->start, start - 1, | |
251 | CDS_JA_RANGE_FREE); | |
252 | ranges[1] = new_range = range_create(start, end, | |
253 | CDS_JA_RANGE_ALLOCATED); | |
254 | ranges[2] = range_create(end + 1, old_range->end, | |
255 | CDS_JA_RANGE_FREE); | |
256 | nr_ranges = 3; | |
257 | } | |
258 | } | |
259 | ||
260 | /* Add replacement ranges to Judy array */ | |
261 | for (i = 0; i < nr_ranges; i++) { | |
262 | ret = cds_ja_add(ja, ranges[i]->start, &ranges[i]->ja_node); | |
263 | assert(!ret); | |
264 | } | |
265 | ||
266 | /* | |
267 | * We add replacement ranges _before_ removing old ranges, so | |
268 | * concurrent traversals will always see one or the other. This | |
269 | * is OK because we temporarily have a duplicate key, and Judy | |
270 | * arrays provide key existence guarantee for lookups performed | |
271 | * concurrently with add followed by del of duplicate keys. | |
272 | */ | |
273 | ||
274 | /* Remove old free range */ | |
275 | ret = cds_ja_del(ja, old_range->start, &old_range->ja_node); | |
276 | assert(!ret); | |
277 | old_range->type = CDS_JA_RANGE_REMOVED; | |
278 | pthread_mutex_unlock(&old_range->lock); | |
279 | ||
280 | rcu_free_range(ja, old_range); | |
281 | ||
282 | return new_range; | |
283 | } | |
284 | ||
285 | int cds_ja_range_del(struct cds_ja *ja, struct cds_ja_range *range) | |
286 | { | |
287 | struct cds_ja_node *prev_node, *next_node; | |
288 | struct cds_ja_range *prev_range, *next_range, *new_range; | |
289 | struct cds_ja_range *merge_ranges[3]; | |
290 | unsigned int nr_merge, i; | |
291 | uint64_t start, end; | |
292 | int ret; | |
293 | ||
294 | retry: | |
295 | nr_merge = 0; | |
296 | prev_node = cds_ja_lookup_below_equal(ja, range->start - 1, NULL); | |
297 | prev_range = caa_container_of(prev_node, struct cds_ja_range, ja_node); | |
298 | if (prev_node && prev_range->type != CDS_JA_RANGE_ALLOCATED) | |
299 | merge_ranges[nr_merge++] = prev_range; | |
300 | ||
301 | merge_ranges[nr_merge++] = range; | |
302 | ||
303 | next_node = cds_ja_lookup_above_equal(ja, range->end + 1, NULL); | |
304 | next_range = caa_container_of(next_node, struct cds_ja_range, ja_node); | |
305 | if (next_node && next_range->type != CDS_JA_RANGE_ALLOCATED) | |
306 | merge_ranges[nr_merge++] = next_range; | |
307 | ||
308 | /* Acquire locks in increasing key order for range merge */ | |
309 | for (i = 0; i < nr_merge; i++) | |
310 | pthread_mutex_lock(&merge_ranges[i]->lock); | |
311 | /* Ensure they are valid */ | |
312 | for (i = 0; i < nr_merge; i++) { | |
313 | if (merge_ranges[i]->type == CDS_JA_RANGE_REMOVED) | |
314 | goto unlock_retry; | |
315 | } | |
316 | ||
317 | /* Create new free range */ | |
318 | start = merge_ranges[0]->start; | |
319 | end = merge_ranges[nr_merge - 1]->end; | |
320 | new_range = range_create(start, end, CDS_JA_RANGE_FREE); | |
321 | ret = cds_ja_add(ja, start, &new_range->ja_node); | |
322 | assert(!ret); | |
323 | ||
324 | /* Remove old ranges */ | |
325 | for (i = 0; i < nr_merge; i++) { | |
326 | ret = cds_ja_del(ja, merge_ranges[i]->start, | |
327 | &merge_ranges[i]->ja_node); | |
328 | assert(!ret); | |
329 | merge_ranges[i]->type = CDS_JA_RANGE_REMOVED; | |
330 | pthread_mutex_unlock(&merge_ranges[i]->lock); | |
331 | rcu_free_range(ja, merge_ranges[i]); | |
332 | } | |
333 | ||
334 | return 0; | |
335 | ||
336 | /* retry paths */ | |
337 | unlock_retry: | |
338 | for (i = 0; i < nr_merge; i++) | |
339 | pthread_mutex_unlock(&merge_ranges[i]->lock); | |
340 | goto retry; | |
341 | } | |
342 | ||
343 | int cds_ja_range_init(struct cds_ja *ja) | |
344 | { | |
345 | struct cds_ja_node *node; | |
346 | struct cds_ja_range *range; | |
347 | int ret; | |
348 | ||
349 | /* | |
350 | * Sanity check: should be empty. | |
351 | */ | |
352 | node = cds_ja_lookup_above_equal(ja, 0, NULL); | |
353 | if (node) | |
354 | return -EINVAL; | |
355 | range = range_create(0, UINT64_MAX, CDS_JA_RANGE_FREE); | |
356 | if (!range) | |
357 | return -EINVAL; | |
358 | ret = cds_ja_add(ja, 0, &range->ja_node); | |
359 | return ret; | |
360 | } | |
361 | ||
362 | int cds_ja_range_fini(struct cds_ja *ja) | |
363 | { | |
364 | uint64_t key; | |
365 | struct cds_ja_node *ja_node; | |
366 | int ret = 0; | |
367 | ||
368 | cds_ja_for_each_key_rcu(ja, key, ja_node) { | |
369 | struct cds_ja_node *tmp_node; | |
370 | ||
371 | cds_ja_for_each_duplicate_safe_rcu(ja_node, tmp_node) { | |
372 | struct cds_ja_range *range; | |
373 | ||
374 | range = caa_container_of(ja_node, | |
375 | struct cds_ja_range, ja_node); | |
376 | ret = cds_ja_del(ja, key, &range->ja_node); | |
377 | if (ret) { | |
378 | goto end; | |
379 | } | |
380 | /* Alone using Judy array, OK to free now */ | |
381 | free_range(range); | |
382 | } | |
383 | } | |
384 | end: | |
385 | return ret; | |
386 | } |