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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 | ||
98d95416 | 18 | #include <linux/random.h> |
88459642 | 19 | #include <linux/sbitmap.h> |
24af1ccf | 20 | #include <linux/seq_file.h> |
88459642 OS |
21 | |
22 | int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift, | |
23 | gfp_t flags, int node) | |
24 | { | |
25 | unsigned int bits_per_word; | |
26 | unsigned int i; | |
27 | ||
28 | if (shift < 0) { | |
29 | shift = ilog2(BITS_PER_LONG); | |
30 | /* | |
31 | * If the bitmap is small, shrink the number of bits per word so | |
32 | * we spread over a few cachelines, at least. If less than 4 | |
33 | * bits, just forget about it, it's not going to work optimally | |
34 | * anyway. | |
35 | */ | |
36 | if (depth >= 4) { | |
37 | while ((4U << shift) > depth) | |
38 | shift--; | |
39 | } | |
40 | } | |
41 | bits_per_word = 1U << shift; | |
42 | if (bits_per_word > BITS_PER_LONG) | |
43 | return -EINVAL; | |
44 | ||
45 | sb->shift = shift; | |
46 | sb->depth = depth; | |
47 | sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word); | |
48 | ||
49 | if (depth == 0) { | |
50 | sb->map = NULL; | |
51 | return 0; | |
52 | } | |
53 | ||
54 | sb->map = kzalloc_node(sb->map_nr * sizeof(*sb->map), flags, node); | |
55 | if (!sb->map) | |
56 | return -ENOMEM; | |
57 | ||
58 | for (i = 0; i < sb->map_nr; i++) { | |
59 | sb->map[i].depth = min(depth, bits_per_word); | |
60 | depth -= sb->map[i].depth; | |
61 | } | |
62 | return 0; | |
63 | } | |
64 | EXPORT_SYMBOL_GPL(sbitmap_init_node); | |
65 | ||
66 | void sbitmap_resize(struct sbitmap *sb, unsigned int depth) | |
67 | { | |
68 | unsigned int bits_per_word = 1U << sb->shift; | |
69 | unsigned int i; | |
70 | ||
71 | sb->depth = depth; | |
72 | sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word); | |
73 | ||
74 | for (i = 0; i < sb->map_nr; i++) { | |
75 | sb->map[i].depth = min(depth, bits_per_word); | |
76 | depth -= sb->map[i].depth; | |
77 | } | |
78 | } | |
79 | EXPORT_SYMBOL_GPL(sbitmap_resize); | |
80 | ||
81 | static int __sbitmap_get_word(struct sbitmap_word *word, unsigned int hint, | |
82 | bool wrap) | |
83 | { | |
84 | unsigned int orig_hint = hint; | |
85 | int nr; | |
86 | ||
87 | while (1) { | |
88 | nr = find_next_zero_bit(&word->word, word->depth, hint); | |
89 | if (unlikely(nr >= word->depth)) { | |
90 | /* | |
91 | * We started with an offset, and we didn't reset the | |
92 | * offset to 0 in a failure case, so start from 0 to | |
93 | * exhaust the map. | |
94 | */ | |
95 | if (orig_hint && hint && wrap) { | |
96 | hint = orig_hint = 0; | |
97 | continue; | |
98 | } | |
99 | return -1; | |
100 | } | |
101 | ||
102 | if (!test_and_set_bit(nr, &word->word)) | |
103 | break; | |
104 | ||
105 | hint = nr + 1; | |
106 | if (hint >= word->depth - 1) | |
107 | hint = 0; | |
108 | } | |
109 | ||
110 | return nr; | |
111 | } | |
112 | ||
113 | int sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint, bool round_robin) | |
114 | { | |
115 | unsigned int i, index; | |
116 | int nr = -1; | |
117 | ||
118 | index = SB_NR_TO_INDEX(sb, alloc_hint); | |
119 | ||
120 | for (i = 0; i < sb->map_nr; i++) { | |
121 | nr = __sbitmap_get_word(&sb->map[index], | |
122 | SB_NR_TO_BIT(sb, alloc_hint), | |
123 | !round_robin); | |
124 | if (nr != -1) { | |
125 | nr += index << sb->shift; | |
126 | break; | |
127 | } | |
128 | ||
129 | /* Jump to next index. */ | |
130 | index++; | |
131 | alloc_hint = index << sb->shift; | |
132 | ||
133 | if (index >= sb->map_nr) { | |
134 | index = 0; | |
135 | alloc_hint = 0; | |
136 | } | |
137 | } | |
138 | ||
139 | return nr; | |
140 | } | |
141 | EXPORT_SYMBOL_GPL(sbitmap_get); | |
142 | ||
143 | bool sbitmap_any_bit_set(const struct sbitmap *sb) | |
144 | { | |
145 | unsigned int i; | |
146 | ||
147 | for (i = 0; i < sb->map_nr; i++) { | |
148 | if (sb->map[i].word) | |
149 | return true; | |
150 | } | |
151 | return false; | |
152 | } | |
153 | EXPORT_SYMBOL_GPL(sbitmap_any_bit_set); | |
154 | ||
155 | bool sbitmap_any_bit_clear(const struct sbitmap *sb) | |
156 | { | |
157 | unsigned int i; | |
158 | ||
159 | for (i = 0; i < sb->map_nr; i++) { | |
160 | const struct sbitmap_word *word = &sb->map[i]; | |
161 | unsigned long ret; | |
162 | ||
163 | ret = find_first_zero_bit(&word->word, word->depth); | |
164 | if (ret < word->depth) | |
165 | return true; | |
166 | } | |
167 | return false; | |
168 | } | |
169 | EXPORT_SYMBOL_GPL(sbitmap_any_bit_clear); | |
170 | ||
171 | unsigned int sbitmap_weight(const struct sbitmap *sb) | |
172 | { | |
60658e0d | 173 | unsigned int i, weight = 0; |
88459642 OS |
174 | |
175 | for (i = 0; i < sb->map_nr; i++) { | |
176 | const struct sbitmap_word *word = &sb->map[i]; | |
177 | ||
178 | weight += bitmap_weight(&word->word, word->depth); | |
179 | } | |
180 | return weight; | |
181 | } | |
182 | EXPORT_SYMBOL_GPL(sbitmap_weight); | |
183 | ||
24af1ccf OS |
184 | void sbitmap_show(struct sbitmap *sb, struct seq_file *m) |
185 | { | |
186 | seq_printf(m, "depth=%u\n", sb->depth); | |
187 | seq_printf(m, "busy=%u\n", sbitmap_weight(sb)); | |
188 | seq_printf(m, "bits_per_word=%u\n", 1U << sb->shift); | |
189 | seq_printf(m, "map_nr=%u\n", sb->map_nr); | |
190 | } | |
191 | EXPORT_SYMBOL_GPL(sbitmap_show); | |
192 | ||
193 | static inline void emit_byte(struct seq_file *m, unsigned int offset, u8 byte) | |
194 | { | |
195 | if ((offset & 0xf) == 0) { | |
196 | if (offset != 0) | |
197 | seq_putc(m, '\n'); | |
198 | seq_printf(m, "%08x:", offset); | |
199 | } | |
200 | if ((offset & 0x1) == 0) | |
201 | seq_putc(m, ' '); | |
202 | seq_printf(m, "%02x", byte); | |
203 | } | |
204 | ||
205 | void sbitmap_bitmap_show(struct sbitmap *sb, struct seq_file *m) | |
206 | { | |
207 | u8 byte = 0; | |
208 | unsigned int byte_bits = 0; | |
209 | unsigned int offset = 0; | |
210 | int i; | |
211 | ||
212 | for (i = 0; i < sb->map_nr; i++) { | |
213 | unsigned long word = READ_ONCE(sb->map[i].word); | |
214 | unsigned int word_bits = READ_ONCE(sb->map[i].depth); | |
215 | ||
216 | while (word_bits > 0) { | |
217 | unsigned int bits = min(8 - byte_bits, word_bits); | |
218 | ||
219 | byte |= (word & (BIT(bits) - 1)) << byte_bits; | |
220 | byte_bits += bits; | |
221 | if (byte_bits == 8) { | |
222 | emit_byte(m, offset, byte); | |
223 | byte = 0; | |
224 | byte_bits = 0; | |
225 | offset++; | |
226 | } | |
227 | word >>= bits; | |
228 | word_bits -= bits; | |
229 | } | |
230 | } | |
231 | if (byte_bits) { | |
232 | emit_byte(m, offset, byte); | |
233 | offset++; | |
234 | } | |
235 | if (offset) | |
236 | seq_putc(m, '\n'); | |
237 | } | |
238 | EXPORT_SYMBOL_GPL(sbitmap_bitmap_show); | |
239 | ||
88459642 OS |
240 | static unsigned int sbq_calc_wake_batch(unsigned int depth) |
241 | { | |
242 | unsigned int wake_batch; | |
243 | ||
244 | /* | |
245 | * For each batch, we wake up one queue. We need to make sure that our | |
246 | * batch size is small enough that the full depth of the bitmap is | |
247 | * enough to wake up all of the queues. | |
248 | */ | |
249 | wake_batch = SBQ_WAKE_BATCH; | |
250 | if (wake_batch > depth / SBQ_WAIT_QUEUES) | |
251 | wake_batch = max(1U, depth / SBQ_WAIT_QUEUES); | |
252 | ||
253 | return wake_batch; | |
254 | } | |
255 | ||
256 | int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth, | |
f4a644db | 257 | int shift, bool round_robin, gfp_t flags, int node) |
88459642 OS |
258 | { |
259 | int ret; | |
260 | int i; | |
261 | ||
262 | ret = sbitmap_init_node(&sbq->sb, depth, shift, flags, node); | |
263 | if (ret) | |
264 | return ret; | |
265 | ||
40aabb67 OS |
266 | sbq->alloc_hint = alloc_percpu_gfp(unsigned int, flags); |
267 | if (!sbq->alloc_hint) { | |
268 | sbitmap_free(&sbq->sb); | |
269 | return -ENOMEM; | |
270 | } | |
271 | ||
98d95416 OS |
272 | if (depth && !round_robin) { |
273 | for_each_possible_cpu(i) | |
274 | *per_cpu_ptr(sbq->alloc_hint, i) = prandom_u32() % depth; | |
275 | } | |
276 | ||
88459642 OS |
277 | sbq->wake_batch = sbq_calc_wake_batch(depth); |
278 | atomic_set(&sbq->wake_index, 0); | |
279 | ||
48e28166 | 280 | sbq->ws = kzalloc_node(SBQ_WAIT_QUEUES * sizeof(*sbq->ws), flags, node); |
88459642 | 281 | if (!sbq->ws) { |
40aabb67 | 282 | free_percpu(sbq->alloc_hint); |
88459642 OS |
283 | sbitmap_free(&sbq->sb); |
284 | return -ENOMEM; | |
285 | } | |
286 | ||
287 | for (i = 0; i < SBQ_WAIT_QUEUES; i++) { | |
288 | init_waitqueue_head(&sbq->ws[i].wait); | |
289 | atomic_set(&sbq->ws[i].wait_cnt, sbq->wake_batch); | |
290 | } | |
f4a644db OS |
291 | |
292 | sbq->round_robin = round_robin; | |
88459642 OS |
293 | return 0; |
294 | } | |
295 | EXPORT_SYMBOL_GPL(sbitmap_queue_init_node); | |
296 | ||
297 | void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth) | |
298 | { | |
6c0ca7ae OS |
299 | unsigned int wake_batch = sbq_calc_wake_batch(depth); |
300 | int i; | |
301 | ||
302 | if (sbq->wake_batch != wake_batch) { | |
303 | WRITE_ONCE(sbq->wake_batch, wake_batch); | |
304 | /* | |
305 | * Pairs with the memory barrier in sbq_wake_up() to ensure that | |
306 | * the batch size is updated before the wait counts. | |
307 | */ | |
308 | smp_mb__before_atomic(); | |
309 | for (i = 0; i < SBQ_WAIT_QUEUES; i++) | |
310 | atomic_set(&sbq->ws[i].wait_cnt, 1); | |
311 | } | |
88459642 OS |
312 | sbitmap_resize(&sbq->sb, depth); |
313 | } | |
314 | EXPORT_SYMBOL_GPL(sbitmap_queue_resize); | |
315 | ||
f4a644db | 316 | int __sbitmap_queue_get(struct sbitmap_queue *sbq) |
40aabb67 | 317 | { |
05fd095d | 318 | unsigned int hint, depth; |
40aabb67 OS |
319 | int nr; |
320 | ||
321 | hint = this_cpu_read(*sbq->alloc_hint); | |
05fd095d OS |
322 | depth = READ_ONCE(sbq->sb.depth); |
323 | if (unlikely(hint >= depth)) { | |
324 | hint = depth ? prandom_u32() % depth : 0; | |
325 | this_cpu_write(*sbq->alloc_hint, hint); | |
326 | } | |
f4a644db | 327 | nr = sbitmap_get(&sbq->sb, hint, sbq->round_robin); |
40aabb67 OS |
328 | |
329 | if (nr == -1) { | |
330 | /* If the map is full, a hint won't do us much good. */ | |
331 | this_cpu_write(*sbq->alloc_hint, 0); | |
f4a644db | 332 | } else if (nr == hint || unlikely(sbq->round_robin)) { |
40aabb67 OS |
333 | /* Only update the hint if we used it. */ |
334 | hint = nr + 1; | |
05fd095d | 335 | if (hint >= depth - 1) |
40aabb67 OS |
336 | hint = 0; |
337 | this_cpu_write(*sbq->alloc_hint, hint); | |
338 | } | |
339 | ||
340 | return nr; | |
341 | } | |
342 | EXPORT_SYMBOL_GPL(__sbitmap_queue_get); | |
343 | ||
88459642 OS |
344 | static struct sbq_wait_state *sbq_wake_ptr(struct sbitmap_queue *sbq) |
345 | { | |
346 | int i, wake_index; | |
347 | ||
348 | wake_index = atomic_read(&sbq->wake_index); | |
349 | for (i = 0; i < SBQ_WAIT_QUEUES; i++) { | |
350 | struct sbq_wait_state *ws = &sbq->ws[wake_index]; | |
351 | ||
352 | if (waitqueue_active(&ws->wait)) { | |
353 | int o = atomic_read(&sbq->wake_index); | |
354 | ||
355 | if (wake_index != o) | |
356 | atomic_cmpxchg(&sbq->wake_index, o, wake_index); | |
357 | return ws; | |
358 | } | |
359 | ||
360 | wake_index = sbq_index_inc(wake_index); | |
361 | } | |
362 | ||
363 | return NULL; | |
364 | } | |
365 | ||
366 | static void sbq_wake_up(struct sbitmap_queue *sbq) | |
367 | { | |
368 | struct sbq_wait_state *ws; | |
6c0ca7ae | 369 | unsigned int wake_batch; |
88459642 OS |
370 | int wait_cnt; |
371 | ||
f66227de OS |
372 | /* |
373 | * Pairs with the memory barrier in set_current_state() to ensure the | |
374 | * proper ordering of clear_bit()/waitqueue_active() in the waker and | |
375 | * test_and_set_bit()/prepare_to_wait()/finish_wait() in the waiter. See | |
376 | * the comment on waitqueue_active(). This is __after_atomic because we | |
377 | * just did clear_bit() in the caller. | |
378 | */ | |
379 | smp_mb__after_atomic(); | |
88459642 OS |
380 | |
381 | ws = sbq_wake_ptr(sbq); | |
382 | if (!ws) | |
383 | return; | |
384 | ||
385 | wait_cnt = atomic_dec_return(&ws->wait_cnt); | |
6c0ca7ae OS |
386 | if (wait_cnt <= 0) { |
387 | wake_batch = READ_ONCE(sbq->wake_batch); | |
388 | /* | |
389 | * Pairs with the memory barrier in sbitmap_queue_resize() to | |
390 | * ensure that we see the batch size update before the wait | |
391 | * count is reset. | |
392 | */ | |
393 | smp_mb__before_atomic(); | |
394 | /* | |
395 | * If there are concurrent callers to sbq_wake_up(), the last | |
396 | * one to decrement the wait count below zero will bump it back | |
397 | * up. If there is a concurrent resize, the count reset will | |
398 | * either cause the cmpxchg to fail or overwrite after the | |
399 | * cmpxchg. | |
400 | */ | |
401 | atomic_cmpxchg(&ws->wait_cnt, wait_cnt, wait_cnt + wake_batch); | |
88459642 OS |
402 | sbq_index_atomic_inc(&sbq->wake_index); |
403 | wake_up(&ws->wait); | |
404 | } | |
405 | } | |
406 | ||
40aabb67 | 407 | void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr, |
f4a644db | 408 | unsigned int cpu) |
88459642 OS |
409 | { |
410 | sbitmap_clear_bit(&sbq->sb, nr); | |
411 | sbq_wake_up(sbq); | |
5c64a8df | 412 | if (likely(!sbq->round_robin && nr < sbq->sb.depth)) |
40aabb67 | 413 | *per_cpu_ptr(sbq->alloc_hint, cpu) = nr; |
88459642 OS |
414 | } |
415 | EXPORT_SYMBOL_GPL(sbitmap_queue_clear); | |
416 | ||
417 | void sbitmap_queue_wake_all(struct sbitmap_queue *sbq) | |
418 | { | |
419 | int i, wake_index; | |
420 | ||
421 | /* | |
f66227de OS |
422 | * Pairs with the memory barrier in set_current_state() like in |
423 | * sbq_wake_up(). | |
88459642 OS |
424 | */ |
425 | smp_mb(); | |
426 | wake_index = atomic_read(&sbq->wake_index); | |
427 | for (i = 0; i < SBQ_WAIT_QUEUES; i++) { | |
428 | struct sbq_wait_state *ws = &sbq->ws[wake_index]; | |
429 | ||
430 | if (waitqueue_active(&ws->wait)) | |
431 | wake_up(&ws->wait); | |
432 | ||
433 | wake_index = sbq_index_inc(wake_index); | |
434 | } | |
435 | } | |
436 | EXPORT_SYMBOL_GPL(sbitmap_queue_wake_all); | |
24af1ccf OS |
437 | |
438 | void sbitmap_queue_show(struct sbitmap_queue *sbq, struct seq_file *m) | |
439 | { | |
440 | bool first; | |
441 | int i; | |
442 | ||
443 | sbitmap_show(&sbq->sb, m); | |
444 | ||
445 | seq_puts(m, "alloc_hint={"); | |
446 | first = true; | |
447 | for_each_possible_cpu(i) { | |
448 | if (!first) | |
449 | seq_puts(m, ", "); | |
450 | first = false; | |
451 | seq_printf(m, "%u", *per_cpu_ptr(sbq->alloc_hint, i)); | |
452 | } | |
453 | seq_puts(m, "}\n"); | |
454 | ||
455 | seq_printf(m, "wake_batch=%u\n", sbq->wake_batch); | |
456 | seq_printf(m, "wake_index=%d\n", atomic_read(&sbq->wake_index)); | |
457 | ||
458 | seq_puts(m, "ws={\n"); | |
459 | for (i = 0; i < SBQ_WAIT_QUEUES; i++) { | |
460 | struct sbq_wait_state *ws = &sbq->ws[i]; | |
461 | ||
462 | seq_printf(m, "\t{.wait_cnt=%d, .wait=%s},\n", | |
463 | atomic_read(&ws->wait_cnt), | |
464 | waitqueue_active(&ws->wait) ? "active" : "inactive"); | |
465 | } | |
466 | seq_puts(m, "}\n"); | |
467 | ||
468 | seq_printf(m, "round_robin=%d\n", sbq->round_robin); | |
469 | } | |
470 | EXPORT_SYMBOL_GPL(sbitmap_queue_show); |