]>
Commit | Line | Data |
---|---|---|
0fc479b1 | 1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
88459642 OS |
2 | /* |
3 | * Fast and scalable bitmaps. | |
4 | * | |
5 | * Copyright (C) 2016 Facebook | |
6 | * Copyright (C) 2013-2014 Jens Axboe | |
88459642 OS |
7 | */ |
8 | ||
9 | #ifndef __LINUX_SCALE_BITMAP_H | |
10 | #define __LINUX_SCALE_BITMAP_H | |
11 | ||
12 | #include <linux/kernel.h> | |
13 | #include <linux/slab.h> | |
14 | ||
14b470b5 AB |
15 | struct seq_file; |
16 | ||
88459642 OS |
17 | /** |
18 | * struct sbitmap_word - Word in a &struct sbitmap. | |
19 | */ | |
20 | struct sbitmap_word { | |
21 | /** | |
ea86ea2c | 22 | * @depth: Number of bits being used in @word/@cleared |
88459642 | 23 | */ |
ea86ea2c | 24 | unsigned long depth; |
88459642 OS |
25 | |
26 | /** | |
ea86ea2c | 27 | * @word: word holding free bits |
88459642 | 28 | */ |
ea86ea2c JA |
29 | unsigned long word ____cacheline_aligned_in_smp; |
30 | ||
31 | /** | |
32 | * @cleared: word holding cleared bits | |
33 | */ | |
34 | unsigned long cleared ____cacheline_aligned_in_smp; | |
88459642 OS |
35 | } ____cacheline_aligned_in_smp; |
36 | ||
37 | /** | |
38 | * struct sbitmap - Scalable bitmap. | |
39 | * | |
40 | * A &struct sbitmap is spread over multiple cachelines to avoid ping-pong. This | |
41 | * trades off higher memory usage for better scalability. | |
42 | */ | |
43 | struct sbitmap { | |
44 | /** | |
45 | * @depth: Number of bits used in the whole bitmap. | |
46 | */ | |
47 | unsigned int depth; | |
48 | ||
49 | /** | |
50 | * @shift: log2(number of bits used per word) | |
51 | */ | |
52 | unsigned int shift; | |
53 | ||
54 | /** | |
55 | * @map_nr: Number of words (cachelines) being used for the bitmap. | |
56 | */ | |
57 | unsigned int map_nr; | |
58 | ||
efe1f3a1 ML |
59 | /** |
60 | * @round_robin: Allocate bits in strict round-robin order. | |
61 | */ | |
62 | bool round_robin; | |
63 | ||
88459642 OS |
64 | /** |
65 | * @map: Allocated bitmap. | |
66 | */ | |
67 | struct sbitmap_word *map; | |
c548e62b ML |
68 | |
69 | /* | |
70 | * @alloc_hint: Cache of last successfully allocated or freed bit. | |
71 | * | |
72 | * This is per-cpu, which allows multiple users to stick to different | |
73 | * cachelines until the map is exhausted. | |
74 | */ | |
75 | unsigned int __percpu *alloc_hint; | |
88459642 OS |
76 | }; |
77 | ||
78 | #define SBQ_WAIT_QUEUES 8 | |
79 | #define SBQ_WAKE_BATCH 8 | |
80 | ||
81 | /** | |
82 | * struct sbq_wait_state - Wait queue in a &struct sbitmap_queue. | |
83 | */ | |
84 | struct sbq_wait_state { | |
85 | /** | |
86 | * @wait_cnt: Number of frees remaining before we wake up. | |
87 | */ | |
88 | atomic_t wait_cnt; | |
89 | ||
90 | /** | |
91 | * @wait: Wait queue. | |
92 | */ | |
93 | wait_queue_head_t wait; | |
94 | } ____cacheline_aligned_in_smp; | |
95 | ||
96 | /** | |
97 | * struct sbitmap_queue - Scalable bitmap with the added ability to wait on free | |
98 | * bits. | |
99 | * | |
100 | * A &struct sbitmap_queue uses multiple wait queues and rolling wakeups to | |
101 | * avoid contention on the wait queue spinlock. This ensures that we don't hit a | |
102 | * scalability wall when we run out of free bits and have to start putting tasks | |
103 | * to sleep. | |
104 | */ | |
105 | struct sbitmap_queue { | |
106 | /** | |
107 | * @sb: Scalable bitmap. | |
108 | */ | |
109 | struct sbitmap sb; | |
110 | ||
111 | /** | |
112 | * @wake_batch: Number of bits which must be freed before we wake up any | |
113 | * waiters. | |
114 | */ | |
115 | unsigned int wake_batch; | |
116 | ||
117 | /** | |
118 | * @wake_index: Next wait queue in @ws to wake up. | |
119 | */ | |
120 | atomic_t wake_index; | |
121 | ||
122 | /** | |
123 | * @ws: Wait queues. | |
124 | */ | |
125 | struct sbq_wait_state *ws; | |
f4a644db | 126 | |
5d2ee712 JA |
127 | /* |
128 | * @ws_active: count of currently active ws waitqueues | |
129 | */ | |
130 | atomic_t ws_active; | |
131 | ||
a3275539 OS |
132 | /** |
133 | * @min_shallow_depth: The minimum shallow depth which may be passed to | |
134 | * sbitmap_queue_get_shallow() or __sbitmap_queue_get_shallow(). | |
135 | */ | |
136 | unsigned int min_shallow_depth; | |
88459642 OS |
137 | }; |
138 | ||
139 | /** | |
140 | * sbitmap_init_node() - Initialize a &struct sbitmap on a specific memory node. | |
141 | * @sb: Bitmap to initialize. | |
142 | * @depth: Number of bits to allocate. | |
143 | * @shift: Use 2^@shift bits per word in the bitmap; if a negative number if | |
144 | * given, a good default is chosen. | |
145 | * @flags: Allocation flags. | |
146 | * @node: Memory node to allocate on. | |
efe1f3a1 ML |
147 | * @round_robin: If true, be stricter about allocation order; always allocate |
148 | * starting from the last allocated bit. This is less efficient | |
149 | * than the default behavior (false). | |
c548e62b ML |
150 | * @alloc_hint: If true, apply percpu hint for where to start searching for |
151 | * a free bit. | |
88459642 OS |
152 | * |
153 | * Return: Zero on success or negative errno on failure. | |
154 | */ | |
155 | int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift, | |
c548e62b | 156 | gfp_t flags, int node, bool round_robin, bool alloc_hint); |
88459642 OS |
157 | |
158 | /** | |
159 | * sbitmap_free() - Free memory used by a &struct sbitmap. | |
160 | * @sb: Bitmap to free. | |
161 | */ | |
162 | static inline void sbitmap_free(struct sbitmap *sb) | |
163 | { | |
c548e62b | 164 | free_percpu(sb->alloc_hint); |
88459642 OS |
165 | kfree(sb->map); |
166 | sb->map = NULL; | |
167 | } | |
168 | ||
169 | /** | |
170 | * sbitmap_resize() - Resize a &struct sbitmap. | |
171 | * @sb: Bitmap to resize. | |
172 | * @depth: New number of bits to resize to. | |
173 | * | |
174 | * Doesn't reallocate anything. It's up to the caller to ensure that the new | |
175 | * depth doesn't exceed the depth that the sb was initialized with. | |
176 | */ | |
177 | void sbitmap_resize(struct sbitmap *sb, unsigned int depth); | |
178 | ||
179 | /** | |
180 | * sbitmap_get() - Try to allocate a free bit from a &struct sbitmap. | |
181 | * @sb: Bitmap to allocate from. | |
88459642 | 182 | * |
4ace53f1 OS |
183 | * This operation provides acquire barrier semantics if it succeeds. |
184 | * | |
88459642 OS |
185 | * Return: Non-negative allocated bit number if successful, -1 otherwise. |
186 | */ | |
c548e62b | 187 | int sbitmap_get(struct sbitmap *sb); |
88459642 | 188 | |
c05e6673 OS |
189 | /** |
190 | * sbitmap_get_shallow() - Try to allocate a free bit from a &struct sbitmap, | |
191 | * limiting the depth used from each word. | |
192 | * @sb: Bitmap to allocate from. | |
c05e6673 OS |
193 | * @shallow_depth: The maximum number of bits to allocate from a single word. |
194 | * | |
195 | * This rather specific operation allows for having multiple users with | |
196 | * different allocation limits. E.g., there can be a high-priority class that | |
197 | * uses sbitmap_get() and a low-priority class that uses sbitmap_get_shallow() | |
198 | * with a @shallow_depth of (1 << (@sb->shift - 1)). Then, the low-priority | |
199 | * class can only allocate half of the total bits in the bitmap, preventing it | |
200 | * from starving out the high-priority class. | |
201 | * | |
202 | * Return: Non-negative allocated bit number if successful, -1 otherwise. | |
203 | */ | |
c548e62b | 204 | int sbitmap_get_shallow(struct sbitmap *sb, unsigned long shallow_depth); |
c05e6673 | 205 | |
88459642 OS |
206 | /** |
207 | * sbitmap_any_bit_set() - Check for a set bit in a &struct sbitmap. | |
208 | * @sb: Bitmap to check. | |
209 | * | |
210 | * Return: true if any bit in the bitmap is set, false otherwise. | |
211 | */ | |
212 | bool sbitmap_any_bit_set(const struct sbitmap *sb); | |
213 | ||
7930d0a0 ML |
214 | #define SB_NR_TO_INDEX(sb, bitnr) ((bitnr) >> (sb)->shift) |
215 | #define SB_NR_TO_BIT(sb, bitnr) ((bitnr) & ((1U << (sb)->shift) - 1U)) | |
216 | ||
88459642 OS |
217 | typedef bool (*sb_for_each_fn)(struct sbitmap *, unsigned int, void *); |
218 | ||
219 | /** | |
7930d0a0 ML |
220 | * __sbitmap_for_each_set() - Iterate over each set bit in a &struct sbitmap. |
221 | * @start: Where to start the iteration. | |
88459642 OS |
222 | * @sb: Bitmap to iterate over. |
223 | * @fn: Callback. Should return true to continue or false to break early. | |
224 | * @data: Pointer to pass to callback. | |
225 | * | |
226 | * This is inline even though it's non-trivial so that the function calls to the | |
227 | * callback will hopefully get optimized away. | |
228 | */ | |
7930d0a0 ML |
229 | static inline void __sbitmap_for_each_set(struct sbitmap *sb, |
230 | unsigned int start, | |
231 | sb_for_each_fn fn, void *data) | |
88459642 | 232 | { |
7930d0a0 ML |
233 | unsigned int index; |
234 | unsigned int nr; | |
235 | unsigned int scanned = 0; | |
88459642 | 236 | |
7930d0a0 ML |
237 | if (start >= sb->depth) |
238 | start = 0; | |
239 | index = SB_NR_TO_INDEX(sb, start); | |
240 | nr = SB_NR_TO_BIT(sb, start); | |
88459642 | 241 | |
7930d0a0 | 242 | while (scanned < sb->depth) { |
8c2def89 OS |
243 | unsigned long word; |
244 | unsigned int depth = min_t(unsigned int, | |
245 | sb->map[index].depth - nr, | |
7930d0a0 | 246 | sb->depth - scanned); |
88459642 | 247 | |
7930d0a0 | 248 | scanned += depth; |
8c2def89 OS |
249 | word = sb->map[index].word & ~sb->map[index].cleared; |
250 | if (!word) | |
7930d0a0 ML |
251 | goto next; |
252 | ||
253 | /* | |
254 | * On the first iteration of the outer loop, we need to add the | |
255 | * bit offset back to the size of the word for find_next_bit(). | |
256 | * On all other iterations, nr is zero, so this is a noop. | |
257 | */ | |
258 | depth += nr; | |
88459642 | 259 | while (1) { |
8c2def89 | 260 | nr = find_next_bit(&word, depth, nr); |
7930d0a0 | 261 | if (nr >= depth) |
88459642 | 262 | break; |
7930d0a0 | 263 | if (!fn(sb, (index << sb->shift) + nr, data)) |
88459642 OS |
264 | return; |
265 | ||
266 | nr++; | |
267 | } | |
7930d0a0 ML |
268 | next: |
269 | nr = 0; | |
270 | if (++index >= sb->map_nr) | |
271 | index = 0; | |
88459642 OS |
272 | } |
273 | } | |
274 | ||
7930d0a0 ML |
275 | /** |
276 | * sbitmap_for_each_set() - Iterate over each set bit in a &struct sbitmap. | |
277 | * @sb: Bitmap to iterate over. | |
278 | * @fn: Callback. Should return true to continue or false to break early. | |
279 | * @data: Pointer to pass to callback. | |
280 | */ | |
281 | static inline void sbitmap_for_each_set(struct sbitmap *sb, sb_for_each_fn fn, | |
282 | void *data) | |
283 | { | |
284 | __sbitmap_for_each_set(sb, 0, fn, data); | |
285 | } | |
88459642 OS |
286 | |
287 | static inline unsigned long *__sbitmap_word(struct sbitmap *sb, | |
288 | unsigned int bitnr) | |
289 | { | |
290 | return &sb->map[SB_NR_TO_INDEX(sb, bitnr)].word; | |
291 | } | |
292 | ||
293 | /* Helpers equivalent to the operations in asm/bitops.h and linux/bitmap.h */ | |
294 | ||
295 | static inline void sbitmap_set_bit(struct sbitmap *sb, unsigned int bitnr) | |
296 | { | |
297 | set_bit(SB_NR_TO_BIT(sb, bitnr), __sbitmap_word(sb, bitnr)); | |
298 | } | |
299 | ||
300 | static inline void sbitmap_clear_bit(struct sbitmap *sb, unsigned int bitnr) | |
301 | { | |
302 | clear_bit(SB_NR_TO_BIT(sb, bitnr), __sbitmap_word(sb, bitnr)); | |
303 | } | |
304 | ||
ea86ea2c JA |
305 | /* |
306 | * This one is special, since it doesn't actually clear the bit, rather it | |
307 | * sets the corresponding bit in the ->cleared mask instead. Paired with | |
1e4471e7 | 308 | * the caller doing sbitmap_deferred_clear() if a given index is full, which |
ea86ea2c JA |
309 | * will clear the previously freed entries in the corresponding ->word. |
310 | */ | |
311 | static inline void sbitmap_deferred_clear_bit(struct sbitmap *sb, unsigned int bitnr) | |
312 | { | |
313 | unsigned long *addr = &sb->map[SB_NR_TO_INDEX(sb, bitnr)].cleared; | |
314 | ||
315 | set_bit(SB_NR_TO_BIT(sb, bitnr), addr); | |
316 | } | |
317 | ||
c548e62b ML |
318 | /* |
319 | * Pair of sbitmap_get, and this one applies both cleared bit and | |
320 | * allocation hint. | |
321 | */ | |
322 | static inline void sbitmap_put(struct sbitmap *sb, unsigned int bitnr) | |
323 | { | |
324 | sbitmap_deferred_clear_bit(sb, bitnr); | |
325 | ||
326 | if (likely(sb->alloc_hint && !sb->round_robin && bitnr < sb->depth)) | |
035e9f47 | 327 | *raw_cpu_ptr(sb->alloc_hint) = bitnr; |
c548e62b ML |
328 | } |
329 | ||
88459642 OS |
330 | static inline int sbitmap_test_bit(struct sbitmap *sb, unsigned int bitnr) |
331 | { | |
332 | return test_bit(SB_NR_TO_BIT(sb, bitnr), __sbitmap_word(sb, bitnr)); | |
333 | } | |
334 | ||
2d13b1ea ML |
335 | static inline int sbitmap_calculate_shift(unsigned int depth) |
336 | { | |
337 | int shift = ilog2(BITS_PER_LONG); | |
338 | ||
339 | /* | |
340 | * If the bitmap is small, shrink the number of bits per word so | |
341 | * we spread over a few cachelines, at least. If less than 4 | |
342 | * bits, just forget about it, it's not going to work optimally | |
343 | * anyway. | |
344 | */ | |
345 | if (depth >= 4) { | |
346 | while ((4U << shift) > depth) | |
347 | shift--; | |
348 | } | |
349 | ||
350 | return shift; | |
351 | } | |
352 | ||
24af1ccf OS |
353 | /** |
354 | * sbitmap_show() - Dump &struct sbitmap information to a &struct seq_file. | |
355 | * @sb: Bitmap to show. | |
356 | * @m: struct seq_file to write to. | |
357 | * | |
358 | * This is intended for debugging. The format may change at any time. | |
359 | */ | |
360 | void sbitmap_show(struct sbitmap *sb, struct seq_file *m); | |
361 | ||
cbb9950b ML |
362 | |
363 | /** | |
364 | * sbitmap_weight() - Return how many set and not cleared bits in a &struct | |
365 | * sbitmap. | |
366 | * @sb: Bitmap to check. | |
367 | * | |
368 | * Return: How many set and not cleared bits set | |
369 | */ | |
370 | unsigned int sbitmap_weight(const struct sbitmap *sb); | |
371 | ||
24af1ccf OS |
372 | /** |
373 | * sbitmap_bitmap_show() - Write a hex dump of a &struct sbitmap to a &struct | |
374 | * seq_file. | |
375 | * @sb: Bitmap to show. | |
376 | * @m: struct seq_file to write to. | |
377 | * | |
378 | * This is intended for debugging. The output isn't guaranteed to be internally | |
379 | * consistent. | |
380 | */ | |
381 | void sbitmap_bitmap_show(struct sbitmap *sb, struct seq_file *m); | |
382 | ||
88459642 OS |
383 | /** |
384 | * sbitmap_queue_init_node() - Initialize a &struct sbitmap_queue on a specific | |
385 | * memory node. | |
386 | * @sbq: Bitmap queue to initialize. | |
387 | * @depth: See sbitmap_init_node(). | |
388 | * @shift: See sbitmap_init_node(). | |
f4a644db | 389 | * @round_robin: See sbitmap_get(). |
88459642 OS |
390 | * @flags: Allocation flags. |
391 | * @node: Memory node to allocate on. | |
392 | * | |
393 | * Return: Zero on success or negative errno on failure. | |
394 | */ | |
395 | int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth, | |
f4a644db | 396 | int shift, bool round_robin, gfp_t flags, int node); |
88459642 OS |
397 | |
398 | /** | |
399 | * sbitmap_queue_free() - Free memory used by a &struct sbitmap_queue. | |
400 | * | |
401 | * @sbq: Bitmap queue to free. | |
402 | */ | |
403 | static inline void sbitmap_queue_free(struct sbitmap_queue *sbq) | |
404 | { | |
405 | kfree(sbq->ws); | |
406 | sbitmap_free(&sbq->sb); | |
407 | } | |
408 | ||
409 | /** | |
410 | * sbitmap_queue_resize() - Resize a &struct sbitmap_queue. | |
411 | * @sbq: Bitmap queue to resize. | |
412 | * @depth: New number of bits to resize to. | |
413 | * | |
414 | * Like sbitmap_resize(), this doesn't reallocate anything. It has to do | |
415 | * some extra work on the &struct sbitmap_queue, so it's not safe to just | |
416 | * resize the underlying &struct sbitmap. | |
417 | */ | |
418 | void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth); | |
419 | ||
40aabb67 OS |
420 | /** |
421 | * __sbitmap_queue_get() - Try to allocate a free bit from a &struct | |
422 | * sbitmap_queue with preemption already disabled. | |
423 | * @sbq: Bitmap queue to allocate from. | |
40aabb67 OS |
424 | * |
425 | * Return: Non-negative allocated bit number if successful, -1 otherwise. | |
426 | */ | |
f4a644db | 427 | int __sbitmap_queue_get(struct sbitmap_queue *sbq); |
40aabb67 | 428 | |
c05e6673 OS |
429 | /** |
430 | * __sbitmap_queue_get_shallow() - Try to allocate a free bit from a &struct | |
431 | * sbitmap_queue, limiting the depth used from each word, with preemption | |
432 | * already disabled. | |
433 | * @sbq: Bitmap queue to allocate from. | |
434 | * @shallow_depth: The maximum number of bits to allocate from a single word. | |
435 | * See sbitmap_get_shallow(). | |
436 | * | |
a3275539 OS |
437 | * If you call this, make sure to call sbitmap_queue_min_shallow_depth() after |
438 | * initializing @sbq. | |
439 | * | |
c05e6673 OS |
440 | * Return: Non-negative allocated bit number if successful, -1 otherwise. |
441 | */ | |
442 | int __sbitmap_queue_get_shallow(struct sbitmap_queue *sbq, | |
443 | unsigned int shallow_depth); | |
444 | ||
40aabb67 OS |
445 | /** |
446 | * sbitmap_queue_get() - Try to allocate a free bit from a &struct | |
447 | * sbitmap_queue. | |
448 | * @sbq: Bitmap queue to allocate from. | |
40aabb67 OS |
449 | * @cpu: Output parameter; will contain the CPU we ran on (e.g., to be passed to |
450 | * sbitmap_queue_clear()). | |
451 | * | |
452 | * Return: Non-negative allocated bit number if successful, -1 otherwise. | |
453 | */ | |
f4a644db | 454 | static inline int sbitmap_queue_get(struct sbitmap_queue *sbq, |
40aabb67 OS |
455 | unsigned int *cpu) |
456 | { | |
457 | int nr; | |
458 | ||
459 | *cpu = get_cpu(); | |
f4a644db | 460 | nr = __sbitmap_queue_get(sbq); |
40aabb67 OS |
461 | put_cpu(); |
462 | return nr; | |
463 | } | |
464 | ||
c05e6673 OS |
465 | /** |
466 | * sbitmap_queue_get_shallow() - Try to allocate a free bit from a &struct | |
467 | * sbitmap_queue, limiting the depth used from each word. | |
468 | * @sbq: Bitmap queue to allocate from. | |
469 | * @cpu: Output parameter; will contain the CPU we ran on (e.g., to be passed to | |
470 | * sbitmap_queue_clear()). | |
471 | * @shallow_depth: The maximum number of bits to allocate from a single word. | |
472 | * See sbitmap_get_shallow(). | |
473 | * | |
a3275539 OS |
474 | * If you call this, make sure to call sbitmap_queue_min_shallow_depth() after |
475 | * initializing @sbq. | |
476 | * | |
c05e6673 OS |
477 | * Return: Non-negative allocated bit number if successful, -1 otherwise. |
478 | */ | |
479 | static inline int sbitmap_queue_get_shallow(struct sbitmap_queue *sbq, | |
480 | unsigned int *cpu, | |
481 | unsigned int shallow_depth) | |
482 | { | |
483 | int nr; | |
484 | ||
485 | *cpu = get_cpu(); | |
486 | nr = __sbitmap_queue_get_shallow(sbq, shallow_depth); | |
487 | put_cpu(); | |
488 | return nr; | |
489 | } | |
490 | ||
a3275539 OS |
491 | /** |
492 | * sbitmap_queue_min_shallow_depth() - Inform a &struct sbitmap_queue of the | |
493 | * minimum shallow depth that will be used. | |
494 | * @sbq: Bitmap queue in question. | |
495 | * @min_shallow_depth: The minimum shallow depth that will be passed to | |
496 | * sbitmap_queue_get_shallow() or __sbitmap_queue_get_shallow(). | |
497 | * | |
498 | * sbitmap_queue_clear() batches wakeups as an optimization. The batch size | |
499 | * depends on the depth of the bitmap. Since the shallow allocation functions | |
500 | * effectively operate with a different depth, the shallow depth must be taken | |
501 | * into account when calculating the batch size. This function must be called | |
502 | * with the minimum shallow depth that will be used. Failure to do so can result | |
503 | * in missed wakeups. | |
504 | */ | |
505 | void sbitmap_queue_min_shallow_depth(struct sbitmap_queue *sbq, | |
506 | unsigned int min_shallow_depth); | |
507 | ||
88459642 OS |
508 | /** |
509 | * sbitmap_queue_clear() - Free an allocated bit and wake up waiters on a | |
510 | * &struct sbitmap_queue. | |
511 | * @sbq: Bitmap to free from. | |
512 | * @nr: Bit number to free. | |
40aabb67 | 513 | * @cpu: CPU the bit was allocated on. |
88459642 | 514 | */ |
40aabb67 | 515 | void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr, |
f4a644db | 516 | unsigned int cpu); |
88459642 OS |
517 | |
518 | static inline int sbq_index_inc(int index) | |
519 | { | |
520 | return (index + 1) & (SBQ_WAIT_QUEUES - 1); | |
521 | } | |
522 | ||
523 | static inline void sbq_index_atomic_inc(atomic_t *index) | |
524 | { | |
525 | int old = atomic_read(index); | |
526 | int new = sbq_index_inc(old); | |
527 | atomic_cmpxchg(index, old, new); | |
528 | } | |
529 | ||
530 | /** | |
531 | * sbq_wait_ptr() - Get the next wait queue to use for a &struct | |
532 | * sbitmap_queue. | |
533 | * @sbq: Bitmap queue to wait on. | |
534 | * @wait_index: A counter per "user" of @sbq. | |
535 | */ | |
536 | static inline struct sbq_wait_state *sbq_wait_ptr(struct sbitmap_queue *sbq, | |
537 | atomic_t *wait_index) | |
538 | { | |
539 | struct sbq_wait_state *ws; | |
540 | ||
541 | ws = &sbq->ws[atomic_read(wait_index)]; | |
542 | sbq_index_atomic_inc(wait_index); | |
543 | return ws; | |
544 | } | |
545 | ||
546 | /** | |
547 | * sbitmap_queue_wake_all() - Wake up everything waiting on a &struct | |
548 | * sbitmap_queue. | |
549 | * @sbq: Bitmap queue to wake up. | |
550 | */ | |
551 | void sbitmap_queue_wake_all(struct sbitmap_queue *sbq); | |
552 | ||
e6fc4649 ML |
553 | /** |
554 | * sbitmap_queue_wake_up() - Wake up some of waiters in one waitqueue | |
555 | * on a &struct sbitmap_queue. | |
556 | * @sbq: Bitmap queue to wake up. | |
557 | */ | |
558 | void sbitmap_queue_wake_up(struct sbitmap_queue *sbq); | |
559 | ||
24af1ccf OS |
560 | /** |
561 | * sbitmap_queue_show() - Dump &struct sbitmap_queue information to a &struct | |
562 | * seq_file. | |
563 | * @sbq: Bitmap queue to show. | |
564 | * @m: struct seq_file to write to. | |
565 | * | |
566 | * This is intended for debugging. The format may change at any time. | |
567 | */ | |
568 | void sbitmap_queue_show(struct sbitmap_queue *sbq, struct seq_file *m); | |
569 | ||
5d2ee712 | 570 | struct sbq_wait { |
9f6b7ef6 | 571 | struct sbitmap_queue *sbq; /* if set, sbq_wait is accounted */ |
5d2ee712 JA |
572 | struct wait_queue_entry wait; |
573 | }; | |
574 | ||
575 | #define DEFINE_SBQ_WAIT(name) \ | |
576 | struct sbq_wait name = { \ | |
9f6b7ef6 | 577 | .sbq = NULL, \ |
5d2ee712 JA |
578 | .wait = { \ |
579 | .private = current, \ | |
580 | .func = autoremove_wake_function, \ | |
581 | .entry = LIST_HEAD_INIT((name).wait.entry), \ | |
582 | } \ | |
583 | } | |
584 | ||
585 | /* | |
586 | * Wrapper around prepare_to_wait_exclusive(), which maintains some extra | |
587 | * internal state. | |
588 | */ | |
589 | void sbitmap_prepare_to_wait(struct sbitmap_queue *sbq, | |
590 | struct sbq_wait_state *ws, | |
591 | struct sbq_wait *sbq_wait, int state); | |
592 | ||
593 | /* | |
594 | * Must be paired with sbitmap_prepare_to_wait(). | |
595 | */ | |
596 | void sbitmap_finish_wait(struct sbitmap_queue *sbq, struct sbq_wait_state *ws, | |
597 | struct sbq_wait *sbq_wait); | |
598 | ||
9f6b7ef6 JA |
599 | /* |
600 | * Wrapper around add_wait_queue(), which maintains some extra internal state | |
601 | */ | |
602 | void sbitmap_add_wait_queue(struct sbitmap_queue *sbq, | |
603 | struct sbq_wait_state *ws, | |
604 | struct sbq_wait *sbq_wait); | |
605 | ||
606 | /* | |
607 | * Must be paired with sbitmap_add_wait_queue() | |
608 | */ | |
609 | void sbitmap_del_wait_queue(struct sbq_wait *sbq_wait); | |
610 | ||
88459642 | 611 | #endif /* __LINUX_SCALE_BITMAP_H */ |