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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 | ||
af8601ad | 18 | #include <linux/sched.h> |
98d95416 | 19 | #include <linux/random.h> |
88459642 | 20 | #include <linux/sbitmap.h> |
24af1ccf | 21 | #include <linux/seq_file.h> |
88459642 OS |
22 | |
23 | int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift, | |
24 | gfp_t flags, int node) | |
25 | { | |
26 | unsigned int bits_per_word; | |
27 | unsigned int i; | |
28 | ||
29 | if (shift < 0) { | |
30 | shift = ilog2(BITS_PER_LONG); | |
31 | /* | |
32 | * If the bitmap is small, shrink the number of bits per word so | |
33 | * we spread over a few cachelines, at least. If less than 4 | |
34 | * bits, just forget about it, it's not going to work optimally | |
35 | * anyway. | |
36 | */ | |
37 | if (depth >= 4) { | |
38 | while ((4U << shift) > depth) | |
39 | shift--; | |
40 | } | |
41 | } | |
42 | bits_per_word = 1U << shift; | |
43 | if (bits_per_word > BITS_PER_LONG) | |
44 | return -EINVAL; | |
45 | ||
46 | sb->shift = shift; | |
47 | sb->depth = depth; | |
48 | sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word); | |
49 | ||
50 | if (depth == 0) { | |
51 | sb->map = NULL; | |
52 | return 0; | |
53 | } | |
54 | ||
55 | sb->map = kzalloc_node(sb->map_nr * sizeof(*sb->map), flags, node); | |
56 | if (!sb->map) | |
57 | return -ENOMEM; | |
58 | ||
59 | for (i = 0; i < sb->map_nr; i++) { | |
60 | sb->map[i].depth = min(depth, bits_per_word); | |
61 | depth -= sb->map[i].depth; | |
62 | } | |
63 | return 0; | |
64 | } | |
65 | EXPORT_SYMBOL_GPL(sbitmap_init_node); | |
66 | ||
67 | void sbitmap_resize(struct sbitmap *sb, unsigned int depth) | |
68 | { | |
69 | unsigned int bits_per_word = 1U << sb->shift; | |
70 | unsigned int i; | |
71 | ||
72 | sb->depth = depth; | |
73 | sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word); | |
74 | ||
75 | for (i = 0; i < sb->map_nr; i++) { | |
76 | sb->map[i].depth = min(depth, bits_per_word); | |
77 | depth -= sb->map[i].depth; | |
78 | } | |
79 | } | |
80 | EXPORT_SYMBOL_GPL(sbitmap_resize); | |
81 | ||
82 | static int __sbitmap_get_word(struct sbitmap_word *word, unsigned int hint, | |
83 | bool wrap) | |
84 | { | |
85 | unsigned int orig_hint = hint; | |
86 | int nr; | |
87 | ||
88 | while (1) { | |
89 | nr = find_next_zero_bit(&word->word, word->depth, hint); | |
90 | if (unlikely(nr >= word->depth)) { | |
91 | /* | |
92 | * We started with an offset, and we didn't reset the | |
93 | * offset to 0 in a failure case, so start from 0 to | |
94 | * exhaust the map. | |
95 | */ | |
96 | if (orig_hint && hint && wrap) { | |
97 | hint = orig_hint = 0; | |
98 | continue; | |
99 | } | |
100 | return -1; | |
101 | } | |
102 | ||
103 | if (!test_and_set_bit(nr, &word->word)) | |
104 | break; | |
105 | ||
106 | hint = nr + 1; | |
107 | if (hint >= word->depth - 1) | |
108 | hint = 0; | |
109 | } | |
110 | ||
111 | return nr; | |
112 | } | |
113 | ||
114 | int sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint, bool round_robin) | |
115 | { | |
116 | unsigned int i, index; | |
117 | int nr = -1; | |
118 | ||
119 | index = SB_NR_TO_INDEX(sb, alloc_hint); | |
120 | ||
121 | for (i = 0; i < sb->map_nr; i++) { | |
122 | nr = __sbitmap_get_word(&sb->map[index], | |
123 | SB_NR_TO_BIT(sb, alloc_hint), | |
124 | !round_robin); | |
125 | if (nr != -1) { | |
126 | nr += index << sb->shift; | |
127 | break; | |
128 | } | |
129 | ||
130 | /* Jump to next index. */ | |
131 | index++; | |
132 | alloc_hint = index << sb->shift; | |
133 | ||
134 | if (index >= sb->map_nr) { | |
135 | index = 0; | |
136 | alloc_hint = 0; | |
137 | } | |
138 | } | |
139 | ||
140 | return nr; | |
141 | } | |
142 | EXPORT_SYMBOL_GPL(sbitmap_get); | |
143 | ||
144 | bool sbitmap_any_bit_set(const struct sbitmap *sb) | |
145 | { | |
146 | unsigned int i; | |
147 | ||
148 | for (i = 0; i < sb->map_nr; i++) { | |
149 | if (sb->map[i].word) | |
150 | return true; | |
151 | } | |
152 | return false; | |
153 | } | |
154 | EXPORT_SYMBOL_GPL(sbitmap_any_bit_set); | |
155 | ||
156 | bool sbitmap_any_bit_clear(const struct sbitmap *sb) | |
157 | { | |
158 | unsigned int i; | |
159 | ||
160 | for (i = 0; i < sb->map_nr; i++) { | |
161 | const struct sbitmap_word *word = &sb->map[i]; | |
162 | unsigned long ret; | |
163 | ||
164 | ret = find_first_zero_bit(&word->word, word->depth); | |
165 | if (ret < word->depth) | |
166 | return true; | |
167 | } | |
168 | return false; | |
169 | } | |
170 | EXPORT_SYMBOL_GPL(sbitmap_any_bit_clear); | |
171 | ||
172 | unsigned int sbitmap_weight(const struct sbitmap *sb) | |
173 | { | |
60658e0d | 174 | unsigned int i, weight = 0; |
88459642 OS |
175 | |
176 | for (i = 0; i < sb->map_nr; i++) { | |
177 | const struct sbitmap_word *word = &sb->map[i]; | |
178 | ||
179 | weight += bitmap_weight(&word->word, word->depth); | |
180 | } | |
181 | return weight; | |
182 | } | |
183 | EXPORT_SYMBOL_GPL(sbitmap_weight); | |
184 | ||
24af1ccf OS |
185 | void sbitmap_show(struct sbitmap *sb, struct seq_file *m) |
186 | { | |
187 | seq_printf(m, "depth=%u\n", sb->depth); | |
188 | seq_printf(m, "busy=%u\n", sbitmap_weight(sb)); | |
189 | seq_printf(m, "bits_per_word=%u\n", 1U << sb->shift); | |
190 | seq_printf(m, "map_nr=%u\n", sb->map_nr); | |
191 | } | |
192 | EXPORT_SYMBOL_GPL(sbitmap_show); | |
193 | ||
194 | static inline void emit_byte(struct seq_file *m, unsigned int offset, u8 byte) | |
195 | { | |
196 | if ((offset & 0xf) == 0) { | |
197 | if (offset != 0) | |
198 | seq_putc(m, '\n'); | |
199 | seq_printf(m, "%08x:", offset); | |
200 | } | |
201 | if ((offset & 0x1) == 0) | |
202 | seq_putc(m, ' '); | |
203 | seq_printf(m, "%02x", byte); | |
204 | } | |
205 | ||
206 | void sbitmap_bitmap_show(struct sbitmap *sb, struct seq_file *m) | |
207 | { | |
208 | u8 byte = 0; | |
209 | unsigned int byte_bits = 0; | |
210 | unsigned int offset = 0; | |
211 | int i; | |
212 | ||
213 | for (i = 0; i < sb->map_nr; i++) { | |
214 | unsigned long word = READ_ONCE(sb->map[i].word); | |
215 | unsigned int word_bits = READ_ONCE(sb->map[i].depth); | |
216 | ||
217 | while (word_bits > 0) { | |
218 | unsigned int bits = min(8 - byte_bits, word_bits); | |
219 | ||
220 | byte |= (word & (BIT(bits) - 1)) << byte_bits; | |
221 | byte_bits += bits; | |
222 | if (byte_bits == 8) { | |
223 | emit_byte(m, offset, byte); | |
224 | byte = 0; | |
225 | byte_bits = 0; | |
226 | offset++; | |
227 | } | |
228 | word >>= bits; | |
229 | word_bits -= bits; | |
230 | } | |
231 | } | |
232 | if (byte_bits) { | |
233 | emit_byte(m, offset, byte); | |
234 | offset++; | |
235 | } | |
236 | if (offset) | |
237 | seq_putc(m, '\n'); | |
238 | } | |
239 | EXPORT_SYMBOL_GPL(sbitmap_bitmap_show); | |
240 | ||
88459642 OS |
241 | static unsigned int sbq_calc_wake_batch(unsigned int depth) |
242 | { | |
243 | unsigned int wake_batch; | |
244 | ||
245 | /* | |
246 | * For each batch, we wake up one queue. We need to make sure that our | |
247 | * batch size is small enough that the full depth of the bitmap is | |
248 | * enough to wake up all of the queues. | |
249 | */ | |
250 | wake_batch = SBQ_WAKE_BATCH; | |
251 | if (wake_batch > depth / SBQ_WAIT_QUEUES) | |
252 | wake_batch = max(1U, depth / SBQ_WAIT_QUEUES); | |
253 | ||
254 | return wake_batch; | |
255 | } | |
256 | ||
257 | int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth, | |
f4a644db | 258 | int shift, bool round_robin, gfp_t flags, int node) |
88459642 OS |
259 | { |
260 | int ret; | |
261 | int i; | |
262 | ||
263 | ret = sbitmap_init_node(&sbq->sb, depth, shift, flags, node); | |
264 | if (ret) | |
265 | return ret; | |
266 | ||
40aabb67 OS |
267 | sbq->alloc_hint = alloc_percpu_gfp(unsigned int, flags); |
268 | if (!sbq->alloc_hint) { | |
269 | sbitmap_free(&sbq->sb); | |
270 | return -ENOMEM; | |
271 | } | |
272 | ||
98d95416 OS |
273 | if (depth && !round_robin) { |
274 | for_each_possible_cpu(i) | |
275 | *per_cpu_ptr(sbq->alloc_hint, i) = prandom_u32() % depth; | |
276 | } | |
277 | ||
88459642 OS |
278 | sbq->wake_batch = sbq_calc_wake_batch(depth); |
279 | atomic_set(&sbq->wake_index, 0); | |
280 | ||
48e28166 | 281 | sbq->ws = kzalloc_node(SBQ_WAIT_QUEUES * sizeof(*sbq->ws), flags, node); |
88459642 | 282 | if (!sbq->ws) { |
40aabb67 | 283 | free_percpu(sbq->alloc_hint); |
88459642 OS |
284 | sbitmap_free(&sbq->sb); |
285 | return -ENOMEM; | |
286 | } | |
287 | ||
288 | for (i = 0; i < SBQ_WAIT_QUEUES; i++) { | |
289 | init_waitqueue_head(&sbq->ws[i].wait); | |
290 | atomic_set(&sbq->ws[i].wait_cnt, sbq->wake_batch); | |
291 | } | |
f4a644db OS |
292 | |
293 | sbq->round_robin = round_robin; | |
88459642 OS |
294 | return 0; |
295 | } | |
296 | EXPORT_SYMBOL_GPL(sbitmap_queue_init_node); | |
297 | ||
298 | void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth) | |
299 | { | |
6c0ca7ae OS |
300 | unsigned int wake_batch = sbq_calc_wake_batch(depth); |
301 | int i; | |
302 | ||
303 | if (sbq->wake_batch != wake_batch) { | |
304 | WRITE_ONCE(sbq->wake_batch, wake_batch); | |
305 | /* | |
306 | * Pairs with the memory barrier in sbq_wake_up() to ensure that | |
307 | * the batch size is updated before the wait counts. | |
308 | */ | |
309 | smp_mb__before_atomic(); | |
310 | for (i = 0; i < SBQ_WAIT_QUEUES; i++) | |
311 | atomic_set(&sbq->ws[i].wait_cnt, 1); | |
312 | } | |
88459642 OS |
313 | sbitmap_resize(&sbq->sb, depth); |
314 | } | |
315 | EXPORT_SYMBOL_GPL(sbitmap_queue_resize); | |
316 | ||
f4a644db | 317 | int __sbitmap_queue_get(struct sbitmap_queue *sbq) |
40aabb67 | 318 | { |
05fd095d | 319 | unsigned int hint, depth; |
40aabb67 OS |
320 | int nr; |
321 | ||
322 | hint = this_cpu_read(*sbq->alloc_hint); | |
05fd095d OS |
323 | depth = READ_ONCE(sbq->sb.depth); |
324 | if (unlikely(hint >= depth)) { | |
325 | hint = depth ? prandom_u32() % depth : 0; | |
326 | this_cpu_write(*sbq->alloc_hint, hint); | |
327 | } | |
f4a644db | 328 | nr = sbitmap_get(&sbq->sb, hint, sbq->round_robin); |
40aabb67 OS |
329 | |
330 | if (nr == -1) { | |
331 | /* If the map is full, a hint won't do us much good. */ | |
332 | this_cpu_write(*sbq->alloc_hint, 0); | |
f4a644db | 333 | } else if (nr == hint || unlikely(sbq->round_robin)) { |
40aabb67 OS |
334 | /* Only update the hint if we used it. */ |
335 | hint = nr + 1; | |
05fd095d | 336 | if (hint >= depth - 1) |
40aabb67 OS |
337 | hint = 0; |
338 | this_cpu_write(*sbq->alloc_hint, hint); | |
339 | } | |
340 | ||
341 | return nr; | |
342 | } | |
343 | EXPORT_SYMBOL_GPL(__sbitmap_queue_get); | |
344 | ||
88459642 OS |
345 | static struct sbq_wait_state *sbq_wake_ptr(struct sbitmap_queue *sbq) |
346 | { | |
347 | int i, wake_index; | |
348 | ||
349 | wake_index = atomic_read(&sbq->wake_index); | |
350 | for (i = 0; i < SBQ_WAIT_QUEUES; i++) { | |
351 | struct sbq_wait_state *ws = &sbq->ws[wake_index]; | |
352 | ||
353 | if (waitqueue_active(&ws->wait)) { | |
354 | int o = atomic_read(&sbq->wake_index); | |
355 | ||
356 | if (wake_index != o) | |
357 | atomic_cmpxchg(&sbq->wake_index, o, wake_index); | |
358 | return ws; | |
359 | } | |
360 | ||
361 | wake_index = sbq_index_inc(wake_index); | |
362 | } | |
363 | ||
364 | return NULL; | |
365 | } | |
366 | ||
367 | static void sbq_wake_up(struct sbitmap_queue *sbq) | |
368 | { | |
369 | struct sbq_wait_state *ws; | |
6c0ca7ae | 370 | unsigned int wake_batch; |
88459642 OS |
371 | int wait_cnt; |
372 | ||
f66227de OS |
373 | /* |
374 | * Pairs with the memory barrier in set_current_state() to ensure the | |
375 | * proper ordering of clear_bit()/waitqueue_active() in the waker and | |
376 | * test_and_set_bit()/prepare_to_wait()/finish_wait() in the waiter. See | |
377 | * the comment on waitqueue_active(). This is __after_atomic because we | |
378 | * just did clear_bit() in the caller. | |
379 | */ | |
380 | smp_mb__after_atomic(); | |
88459642 OS |
381 | |
382 | ws = sbq_wake_ptr(sbq); | |
383 | if (!ws) | |
384 | return; | |
385 | ||
386 | wait_cnt = atomic_dec_return(&ws->wait_cnt); | |
6c0ca7ae OS |
387 | if (wait_cnt <= 0) { |
388 | wake_batch = READ_ONCE(sbq->wake_batch); | |
389 | /* | |
390 | * Pairs with the memory barrier in sbitmap_queue_resize() to | |
391 | * ensure that we see the batch size update before the wait | |
392 | * count is reset. | |
393 | */ | |
394 | smp_mb__before_atomic(); | |
395 | /* | |
396 | * If there are concurrent callers to sbq_wake_up(), the last | |
397 | * one to decrement the wait count below zero will bump it back | |
398 | * up. If there is a concurrent resize, the count reset will | |
399 | * either cause the cmpxchg to fail or overwrite after the | |
400 | * cmpxchg. | |
401 | */ | |
402 | atomic_cmpxchg(&ws->wait_cnt, wait_cnt, wait_cnt + wake_batch); | |
88459642 OS |
403 | sbq_index_atomic_inc(&sbq->wake_index); |
404 | wake_up(&ws->wait); | |
405 | } | |
406 | } | |
407 | ||
40aabb67 | 408 | void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr, |
f4a644db | 409 | unsigned int cpu) |
88459642 OS |
410 | { |
411 | sbitmap_clear_bit(&sbq->sb, nr); | |
412 | sbq_wake_up(sbq); | |
5c64a8df | 413 | if (likely(!sbq->round_robin && nr < sbq->sb.depth)) |
40aabb67 | 414 | *per_cpu_ptr(sbq->alloc_hint, cpu) = nr; |
88459642 OS |
415 | } |
416 | EXPORT_SYMBOL_GPL(sbitmap_queue_clear); | |
417 | ||
418 | void sbitmap_queue_wake_all(struct sbitmap_queue *sbq) | |
419 | { | |
420 | int i, wake_index; | |
421 | ||
422 | /* | |
f66227de OS |
423 | * Pairs with the memory barrier in set_current_state() like in |
424 | * sbq_wake_up(). | |
88459642 OS |
425 | */ |
426 | smp_mb(); | |
427 | wake_index = atomic_read(&sbq->wake_index); | |
428 | for (i = 0; i < SBQ_WAIT_QUEUES; i++) { | |
429 | struct sbq_wait_state *ws = &sbq->ws[wake_index]; | |
430 | ||
431 | if (waitqueue_active(&ws->wait)) | |
432 | wake_up(&ws->wait); | |
433 | ||
434 | wake_index = sbq_index_inc(wake_index); | |
435 | } | |
436 | } | |
437 | EXPORT_SYMBOL_GPL(sbitmap_queue_wake_all); | |
24af1ccf OS |
438 | |
439 | void sbitmap_queue_show(struct sbitmap_queue *sbq, struct seq_file *m) | |
440 | { | |
441 | bool first; | |
442 | int i; | |
443 | ||
444 | sbitmap_show(&sbq->sb, m); | |
445 | ||
446 | seq_puts(m, "alloc_hint={"); | |
447 | first = true; | |
448 | for_each_possible_cpu(i) { | |
449 | if (!first) | |
450 | seq_puts(m, ", "); | |
451 | first = false; | |
452 | seq_printf(m, "%u", *per_cpu_ptr(sbq->alloc_hint, i)); | |
453 | } | |
454 | seq_puts(m, "}\n"); | |
455 | ||
456 | seq_printf(m, "wake_batch=%u\n", sbq->wake_batch); | |
457 | seq_printf(m, "wake_index=%d\n", atomic_read(&sbq->wake_index)); | |
458 | ||
459 | seq_puts(m, "ws={\n"); | |
460 | for (i = 0; i < SBQ_WAIT_QUEUES; i++) { | |
461 | struct sbq_wait_state *ws = &sbq->ws[i]; | |
462 | ||
463 | seq_printf(m, "\t{.wait_cnt=%d, .wait=%s},\n", | |
464 | atomic_read(&ws->wait_cnt), | |
465 | waitqueue_active(&ws->wait) ? "active" : "inactive"); | |
466 | } | |
467 | seq_puts(m, "}\n"); | |
468 | ||
469 | seq_printf(m, "round_robin=%d\n", sbq->round_robin); | |
470 | } | |
471 | EXPORT_SYMBOL_GPL(sbitmap_queue_show); |