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88459642 OS |
1 | /* |
2 | * Copyright (C) 2016 Facebook | |
3 | * Copyright (C) 2013-2014 Jens Axboe | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or | |
6 | * modify it under the terms of the GNU General Public | |
7 | * License v2 as published by the Free Software Foundation. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
12 | * General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program. If not, see <https://www.gnu.org/licenses/>. | |
16 | */ | |
17 | ||
18 | #include <linux/sbitmap.h> | |
19 | ||
20 | int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift, | |
21 | gfp_t flags, int node) | |
22 | { | |
23 | unsigned int bits_per_word; | |
24 | unsigned int i; | |
25 | ||
26 | if (shift < 0) { | |
27 | shift = ilog2(BITS_PER_LONG); | |
28 | /* | |
29 | * If the bitmap is small, shrink the number of bits per word so | |
30 | * we spread over a few cachelines, at least. If less than 4 | |
31 | * bits, just forget about it, it's not going to work optimally | |
32 | * anyway. | |
33 | */ | |
34 | if (depth >= 4) { | |
35 | while ((4U << shift) > depth) | |
36 | shift--; | |
37 | } | |
38 | } | |
39 | bits_per_word = 1U << shift; | |
40 | if (bits_per_word > BITS_PER_LONG) | |
41 | return -EINVAL; | |
42 | ||
43 | sb->shift = shift; | |
44 | sb->depth = depth; | |
45 | sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word); | |
46 | ||
47 | if (depth == 0) { | |
48 | sb->map = NULL; | |
49 | return 0; | |
50 | } | |
51 | ||
52 | sb->map = kzalloc_node(sb->map_nr * sizeof(*sb->map), flags, node); | |
53 | if (!sb->map) | |
54 | return -ENOMEM; | |
55 | ||
56 | for (i = 0; i < sb->map_nr; i++) { | |
57 | sb->map[i].depth = min(depth, bits_per_word); | |
58 | depth -= sb->map[i].depth; | |
59 | } | |
60 | return 0; | |
61 | } | |
62 | EXPORT_SYMBOL_GPL(sbitmap_init_node); | |
63 | ||
64 | void sbitmap_resize(struct sbitmap *sb, unsigned int depth) | |
65 | { | |
66 | unsigned int bits_per_word = 1U << sb->shift; | |
67 | unsigned int i; | |
68 | ||
69 | sb->depth = depth; | |
70 | sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word); | |
71 | ||
72 | for (i = 0; i < sb->map_nr; i++) { | |
73 | sb->map[i].depth = min(depth, bits_per_word); | |
74 | depth -= sb->map[i].depth; | |
75 | } | |
76 | } | |
77 | EXPORT_SYMBOL_GPL(sbitmap_resize); | |
78 | ||
79 | static int __sbitmap_get_word(struct sbitmap_word *word, unsigned int hint, | |
80 | bool wrap) | |
81 | { | |
82 | unsigned int orig_hint = hint; | |
83 | int nr; | |
84 | ||
85 | while (1) { | |
86 | nr = find_next_zero_bit(&word->word, word->depth, hint); | |
87 | if (unlikely(nr >= word->depth)) { | |
88 | /* | |
89 | * We started with an offset, and we didn't reset the | |
90 | * offset to 0 in a failure case, so start from 0 to | |
91 | * exhaust the map. | |
92 | */ | |
93 | if (orig_hint && hint && wrap) { | |
94 | hint = orig_hint = 0; | |
95 | continue; | |
96 | } | |
97 | return -1; | |
98 | } | |
99 | ||
100 | if (!test_and_set_bit(nr, &word->word)) | |
101 | break; | |
102 | ||
103 | hint = nr + 1; | |
104 | if (hint >= word->depth - 1) | |
105 | hint = 0; | |
106 | } | |
107 | ||
108 | return nr; | |
109 | } | |
110 | ||
111 | int sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint, bool round_robin) | |
112 | { | |
113 | unsigned int i, index; | |
114 | int nr = -1; | |
115 | ||
116 | index = SB_NR_TO_INDEX(sb, alloc_hint); | |
117 | ||
118 | for (i = 0; i < sb->map_nr; i++) { | |
119 | nr = __sbitmap_get_word(&sb->map[index], | |
120 | SB_NR_TO_BIT(sb, alloc_hint), | |
121 | !round_robin); | |
122 | if (nr != -1) { | |
123 | nr += index << sb->shift; | |
124 | break; | |
125 | } | |
126 | ||
127 | /* Jump to next index. */ | |
128 | index++; | |
129 | alloc_hint = index << sb->shift; | |
130 | ||
131 | if (index >= sb->map_nr) { | |
132 | index = 0; | |
133 | alloc_hint = 0; | |
134 | } | |
135 | } | |
136 | ||
137 | return nr; | |
138 | } | |
139 | EXPORT_SYMBOL_GPL(sbitmap_get); | |
140 | ||
141 | bool sbitmap_any_bit_set(const struct sbitmap *sb) | |
142 | { | |
143 | unsigned int i; | |
144 | ||
145 | for (i = 0; i < sb->map_nr; i++) { | |
146 | if (sb->map[i].word) | |
147 | return true; | |
148 | } | |
149 | return false; | |
150 | } | |
151 | EXPORT_SYMBOL_GPL(sbitmap_any_bit_set); | |
152 | ||
153 | bool sbitmap_any_bit_clear(const struct sbitmap *sb) | |
154 | { | |
155 | unsigned int i; | |
156 | ||
157 | for (i = 0; i < sb->map_nr; i++) { | |
158 | const struct sbitmap_word *word = &sb->map[i]; | |
159 | unsigned long ret; | |
160 | ||
161 | ret = find_first_zero_bit(&word->word, word->depth); | |
162 | if (ret < word->depth) | |
163 | return true; | |
164 | } | |
165 | return false; | |
166 | } | |
167 | EXPORT_SYMBOL_GPL(sbitmap_any_bit_clear); | |
168 | ||
169 | unsigned int sbitmap_weight(const struct sbitmap *sb) | |
170 | { | |
171 | unsigned int i, weight; | |
172 | ||
173 | for (i = 0; i < sb->map_nr; i++) { | |
174 | const struct sbitmap_word *word = &sb->map[i]; | |
175 | ||
176 | weight += bitmap_weight(&word->word, word->depth); | |
177 | } | |
178 | return weight; | |
179 | } | |
180 | EXPORT_SYMBOL_GPL(sbitmap_weight); | |
181 | ||
182 | static unsigned int sbq_calc_wake_batch(unsigned int depth) | |
183 | { | |
184 | unsigned int wake_batch; | |
185 | ||
186 | /* | |
187 | * For each batch, we wake up one queue. We need to make sure that our | |
188 | * batch size is small enough that the full depth of the bitmap is | |
189 | * enough to wake up all of the queues. | |
190 | */ | |
191 | wake_batch = SBQ_WAKE_BATCH; | |
192 | if (wake_batch > depth / SBQ_WAIT_QUEUES) | |
193 | wake_batch = max(1U, depth / SBQ_WAIT_QUEUES); | |
194 | ||
195 | return wake_batch; | |
196 | } | |
197 | ||
198 | int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth, | |
f4a644db | 199 | int shift, bool round_robin, gfp_t flags, int node) |
88459642 OS |
200 | { |
201 | int ret; | |
202 | int i; | |
203 | ||
204 | ret = sbitmap_init_node(&sbq->sb, depth, shift, flags, node); | |
205 | if (ret) | |
206 | return ret; | |
207 | ||
40aabb67 OS |
208 | sbq->alloc_hint = alloc_percpu_gfp(unsigned int, flags); |
209 | if (!sbq->alloc_hint) { | |
210 | sbitmap_free(&sbq->sb); | |
211 | return -ENOMEM; | |
212 | } | |
213 | ||
88459642 OS |
214 | sbq->wake_batch = sbq_calc_wake_batch(depth); |
215 | atomic_set(&sbq->wake_index, 0); | |
216 | ||
48e28166 | 217 | sbq->ws = kzalloc_node(SBQ_WAIT_QUEUES * sizeof(*sbq->ws), flags, node); |
88459642 | 218 | if (!sbq->ws) { |
40aabb67 | 219 | free_percpu(sbq->alloc_hint); |
88459642 OS |
220 | sbitmap_free(&sbq->sb); |
221 | return -ENOMEM; | |
222 | } | |
223 | ||
224 | for (i = 0; i < SBQ_WAIT_QUEUES; i++) { | |
225 | init_waitqueue_head(&sbq->ws[i].wait); | |
226 | atomic_set(&sbq->ws[i].wait_cnt, sbq->wake_batch); | |
227 | } | |
f4a644db OS |
228 | |
229 | sbq->round_robin = round_robin; | |
88459642 OS |
230 | return 0; |
231 | } | |
232 | EXPORT_SYMBOL_GPL(sbitmap_queue_init_node); | |
233 | ||
234 | void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth) | |
235 | { | |
236 | sbq->wake_batch = sbq_calc_wake_batch(depth); | |
237 | sbitmap_resize(&sbq->sb, depth); | |
238 | } | |
239 | EXPORT_SYMBOL_GPL(sbitmap_queue_resize); | |
240 | ||
f4a644db | 241 | int __sbitmap_queue_get(struct sbitmap_queue *sbq) |
40aabb67 OS |
242 | { |
243 | unsigned int hint; | |
244 | int nr; | |
245 | ||
246 | hint = this_cpu_read(*sbq->alloc_hint); | |
f4a644db | 247 | nr = sbitmap_get(&sbq->sb, hint, sbq->round_robin); |
40aabb67 OS |
248 | |
249 | if (nr == -1) { | |
250 | /* If the map is full, a hint won't do us much good. */ | |
251 | this_cpu_write(*sbq->alloc_hint, 0); | |
f4a644db | 252 | } else if (nr == hint || unlikely(sbq->round_robin)) { |
40aabb67 OS |
253 | /* Only update the hint if we used it. */ |
254 | hint = nr + 1; | |
255 | if (hint >= sbq->sb.depth - 1) | |
256 | hint = 0; | |
257 | this_cpu_write(*sbq->alloc_hint, hint); | |
258 | } | |
259 | ||
260 | return nr; | |
261 | } | |
262 | EXPORT_SYMBOL_GPL(__sbitmap_queue_get); | |
263 | ||
88459642 OS |
264 | static struct sbq_wait_state *sbq_wake_ptr(struct sbitmap_queue *sbq) |
265 | { | |
266 | int i, wake_index; | |
267 | ||
268 | wake_index = atomic_read(&sbq->wake_index); | |
269 | for (i = 0; i < SBQ_WAIT_QUEUES; i++) { | |
270 | struct sbq_wait_state *ws = &sbq->ws[wake_index]; | |
271 | ||
272 | if (waitqueue_active(&ws->wait)) { | |
273 | int o = atomic_read(&sbq->wake_index); | |
274 | ||
275 | if (wake_index != o) | |
276 | atomic_cmpxchg(&sbq->wake_index, o, wake_index); | |
277 | return ws; | |
278 | } | |
279 | ||
280 | wake_index = sbq_index_inc(wake_index); | |
281 | } | |
282 | ||
283 | return NULL; | |
284 | } | |
285 | ||
286 | static void sbq_wake_up(struct sbitmap_queue *sbq) | |
287 | { | |
288 | struct sbq_wait_state *ws; | |
289 | int wait_cnt; | |
290 | ||
291 | /* Ensure that the wait list checks occur after clear_bit(). */ | |
292 | smp_mb(); | |
293 | ||
294 | ws = sbq_wake_ptr(sbq); | |
295 | if (!ws) | |
296 | return; | |
297 | ||
298 | wait_cnt = atomic_dec_return(&ws->wait_cnt); | |
299 | if (unlikely(wait_cnt < 0)) | |
300 | wait_cnt = atomic_inc_return(&ws->wait_cnt); | |
301 | if (wait_cnt == 0) { | |
302 | atomic_add(sbq->wake_batch, &ws->wait_cnt); | |
303 | sbq_index_atomic_inc(&sbq->wake_index); | |
304 | wake_up(&ws->wait); | |
305 | } | |
306 | } | |
307 | ||
40aabb67 | 308 | void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr, |
f4a644db | 309 | unsigned int cpu) |
88459642 OS |
310 | { |
311 | sbitmap_clear_bit(&sbq->sb, nr); | |
312 | sbq_wake_up(sbq); | |
f4a644db | 313 | if (likely(!sbq->round_robin)) |
40aabb67 | 314 | *per_cpu_ptr(sbq->alloc_hint, cpu) = nr; |
88459642 OS |
315 | } |
316 | EXPORT_SYMBOL_GPL(sbitmap_queue_clear); | |
317 | ||
318 | void sbitmap_queue_wake_all(struct sbitmap_queue *sbq) | |
319 | { | |
320 | int i, wake_index; | |
321 | ||
322 | /* | |
323 | * Make sure all changes prior to this are visible from other CPUs. | |
324 | */ | |
325 | smp_mb(); | |
326 | wake_index = atomic_read(&sbq->wake_index); | |
327 | for (i = 0; i < SBQ_WAIT_QUEUES; i++) { | |
328 | struct sbq_wait_state *ws = &sbq->ws[wake_index]; | |
329 | ||
330 | if (waitqueue_active(&ws->wait)) | |
331 | wake_up(&ws->wait); | |
332 | ||
333 | wake_index = sbq_index_inc(wake_index); | |
334 | } | |
335 | } | |
336 | EXPORT_SYMBOL_GPL(sbitmap_queue_wake_all); |