Commit | Line | Data |
---|---|---|
7a8e76a3 SR |
1 | /* |
2 | * Generic ring buffer | |
3 | * | |
4 | * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com> | |
5 | */ | |
6 | #include <linux/ring_buffer.h> | |
7 | #include <linux/spinlock.h> | |
8 | #include <linux/debugfs.h> | |
9 | #include <linux/uaccess.h> | |
10 | #include <linux/module.h> | |
11 | #include <linux/percpu.h> | |
12 | #include <linux/mutex.h> | |
13 | #include <linux/sched.h> /* used for sched_clock() (for now) */ | |
14 | #include <linux/init.h> | |
15 | #include <linux/hash.h> | |
16 | #include <linux/list.h> | |
17 | #include <linux/fs.h> | |
18 | ||
19 | /* Up this if you want to test the TIME_EXTENTS and normalization */ | |
20 | #define DEBUG_SHIFT 0 | |
21 | ||
22 | /* FIXME!!! */ | |
23 | u64 ring_buffer_time_stamp(int cpu) | |
24 | { | |
25 | /* shift to debug/test normalization and TIME_EXTENTS */ | |
26 | return sched_clock() << DEBUG_SHIFT; | |
27 | } | |
28 | ||
29 | void ring_buffer_normalize_time_stamp(int cpu, u64 *ts) | |
30 | { | |
31 | /* Just stupid testing the normalize function and deltas */ | |
32 | *ts >>= DEBUG_SHIFT; | |
33 | } | |
34 | ||
35 | #define RB_EVNT_HDR_SIZE (sizeof(struct ring_buffer_event)) | |
36 | #define RB_ALIGNMENT_SHIFT 2 | |
37 | #define RB_ALIGNMENT (1 << RB_ALIGNMENT_SHIFT) | |
38 | #define RB_MAX_SMALL_DATA 28 | |
39 | ||
40 | enum { | |
41 | RB_LEN_TIME_EXTEND = 8, | |
42 | RB_LEN_TIME_STAMP = 16, | |
43 | }; | |
44 | ||
45 | /* inline for ring buffer fast paths */ | |
46 | static inline unsigned | |
47 | rb_event_length(struct ring_buffer_event *event) | |
48 | { | |
49 | unsigned length; | |
50 | ||
51 | switch (event->type) { | |
52 | case RINGBUF_TYPE_PADDING: | |
53 | /* undefined */ | |
54 | return -1; | |
55 | ||
56 | case RINGBUF_TYPE_TIME_EXTEND: | |
57 | return RB_LEN_TIME_EXTEND; | |
58 | ||
59 | case RINGBUF_TYPE_TIME_STAMP: | |
60 | return RB_LEN_TIME_STAMP; | |
61 | ||
62 | case RINGBUF_TYPE_DATA: | |
63 | if (event->len) | |
64 | length = event->len << RB_ALIGNMENT_SHIFT; | |
65 | else | |
66 | length = event->array[0]; | |
67 | return length + RB_EVNT_HDR_SIZE; | |
68 | default: | |
69 | BUG(); | |
70 | } | |
71 | /* not hit */ | |
72 | return 0; | |
73 | } | |
74 | ||
75 | /** | |
76 | * ring_buffer_event_length - return the length of the event | |
77 | * @event: the event to get the length of | |
78 | */ | |
79 | unsigned ring_buffer_event_length(struct ring_buffer_event *event) | |
80 | { | |
81 | return rb_event_length(event); | |
82 | } | |
83 | ||
84 | /* inline for ring buffer fast paths */ | |
85 | static inline void * | |
86 | rb_event_data(struct ring_buffer_event *event) | |
87 | { | |
88 | BUG_ON(event->type != RINGBUF_TYPE_DATA); | |
89 | /* If length is in len field, then array[0] has the data */ | |
90 | if (event->len) | |
91 | return (void *)&event->array[0]; | |
92 | /* Otherwise length is in array[0] and array[1] has the data */ | |
93 | return (void *)&event->array[1]; | |
94 | } | |
95 | ||
96 | /** | |
97 | * ring_buffer_event_data - return the data of the event | |
98 | * @event: the event to get the data from | |
99 | */ | |
100 | void *ring_buffer_event_data(struct ring_buffer_event *event) | |
101 | { | |
102 | return rb_event_data(event); | |
103 | } | |
104 | ||
105 | #define for_each_buffer_cpu(buffer, cpu) \ | |
106 | for_each_cpu_mask(cpu, buffer->cpumask) | |
107 | ||
108 | #define TS_SHIFT 27 | |
109 | #define TS_MASK ((1ULL << TS_SHIFT) - 1) | |
110 | #define TS_DELTA_TEST (~TS_MASK) | |
111 | ||
112 | /* | |
113 | * This hack stolen from mm/slob.c. | |
114 | * We can store per page timing information in the page frame of the page. | |
115 | * Thanks to Peter Zijlstra for suggesting this idea. | |
116 | */ | |
117 | struct buffer_page { | |
e4c2ce82 | 118 | u64 time_stamp; /* page time stamp */ |
bf41a158 SR |
119 | local_t write; /* index for next write */ |
120 | local_t commit; /* write commited index */ | |
6f807acd | 121 | unsigned read; /* index for next read */ |
e4c2ce82 SR |
122 | struct list_head list; /* list of free pages */ |
123 | void *page; /* Actual data page */ | |
7a8e76a3 SR |
124 | }; |
125 | ||
ed56829c SR |
126 | /* |
127 | * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing | |
128 | * this issue out. | |
129 | */ | |
130 | static inline void free_buffer_page(struct buffer_page *bpage) | |
131 | { | |
e4c2ce82 | 132 | if (bpage->page) |
6ae2a076 | 133 | free_page((unsigned long)bpage->page); |
e4c2ce82 | 134 | kfree(bpage); |
ed56829c SR |
135 | } |
136 | ||
7a8e76a3 SR |
137 | /* |
138 | * We need to fit the time_stamp delta into 27 bits. | |
139 | */ | |
140 | static inline int test_time_stamp(u64 delta) | |
141 | { | |
142 | if (delta & TS_DELTA_TEST) | |
143 | return 1; | |
144 | return 0; | |
145 | } | |
146 | ||
147 | #define BUF_PAGE_SIZE PAGE_SIZE | |
148 | ||
149 | /* | |
150 | * head_page == tail_page && head == tail then buffer is empty. | |
151 | */ | |
152 | struct ring_buffer_per_cpu { | |
153 | int cpu; | |
154 | struct ring_buffer *buffer; | |
155 | spinlock_t lock; | |
156 | struct lock_class_key lock_key; | |
157 | struct list_head pages; | |
6f807acd SR |
158 | struct buffer_page *head_page; /* read from head */ |
159 | struct buffer_page *tail_page; /* write to tail */ | |
bf41a158 | 160 | struct buffer_page *commit_page; /* commited pages */ |
d769041f | 161 | struct buffer_page *reader_page; |
7a8e76a3 SR |
162 | unsigned long overrun; |
163 | unsigned long entries; | |
164 | u64 write_stamp; | |
165 | u64 read_stamp; | |
166 | atomic_t record_disabled; | |
167 | }; | |
168 | ||
169 | struct ring_buffer { | |
170 | unsigned long size; | |
171 | unsigned pages; | |
172 | unsigned flags; | |
173 | int cpus; | |
174 | cpumask_t cpumask; | |
175 | atomic_t record_disabled; | |
176 | ||
177 | struct mutex mutex; | |
178 | ||
179 | struct ring_buffer_per_cpu **buffers; | |
180 | }; | |
181 | ||
182 | struct ring_buffer_iter { | |
183 | struct ring_buffer_per_cpu *cpu_buffer; | |
184 | unsigned long head; | |
185 | struct buffer_page *head_page; | |
186 | u64 read_stamp; | |
187 | }; | |
188 | ||
bf41a158 SR |
189 | #define RB_WARN_ON(buffer, cond) \ |
190 | do { \ | |
191 | if (unlikely(cond)) { \ | |
192 | atomic_inc(&buffer->record_disabled); \ | |
193 | WARN_ON(1); \ | |
194 | } \ | |
195 | } while (0) | |
196 | ||
197 | #define RB_WARN_ON_RET(buffer, cond) \ | |
198 | do { \ | |
199 | if (unlikely(cond)) { \ | |
200 | atomic_inc(&buffer->record_disabled); \ | |
201 | WARN_ON(1); \ | |
202 | return -1; \ | |
203 | } \ | |
204 | } while (0) | |
205 | ||
206 | #define RB_WARN_ON_ONCE(buffer, cond) \ | |
207 | do { \ | |
208 | static int once; \ | |
209 | if (unlikely(cond) && !once) { \ | |
210 | once++; \ | |
211 | atomic_inc(&buffer->record_disabled); \ | |
212 | WARN_ON(1); \ | |
213 | } \ | |
214 | } while (0) | |
7a8e76a3 SR |
215 | |
216 | /** | |
217 | * check_pages - integrity check of buffer pages | |
218 | * @cpu_buffer: CPU buffer with pages to test | |
219 | * | |
220 | * As a safty measure we check to make sure the data pages have not | |
221 | * been corrupted. | |
222 | */ | |
223 | static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) | |
224 | { | |
225 | struct list_head *head = &cpu_buffer->pages; | |
226 | struct buffer_page *page, *tmp; | |
227 | ||
bf41a158 SR |
228 | RB_WARN_ON_RET(cpu_buffer, head->next->prev != head); |
229 | RB_WARN_ON_RET(cpu_buffer, head->prev->next != head); | |
7a8e76a3 SR |
230 | |
231 | list_for_each_entry_safe(page, tmp, head, list) { | |
bf41a158 SR |
232 | RB_WARN_ON_RET(cpu_buffer, |
233 | page->list.next->prev != &page->list); | |
234 | RB_WARN_ON_RET(cpu_buffer, | |
235 | page->list.prev->next != &page->list); | |
7a8e76a3 SR |
236 | } |
237 | ||
238 | return 0; | |
239 | } | |
240 | ||
7a8e76a3 SR |
241 | static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, |
242 | unsigned nr_pages) | |
243 | { | |
244 | struct list_head *head = &cpu_buffer->pages; | |
245 | struct buffer_page *page, *tmp; | |
246 | unsigned long addr; | |
247 | LIST_HEAD(pages); | |
248 | unsigned i; | |
249 | ||
250 | for (i = 0; i < nr_pages; i++) { | |
e4c2ce82 | 251 | page = kzalloc_node(ALIGN(sizeof(*page), cache_line_size()), |
aa1e0e3b | 252 | GFP_KERNEL, cpu_to_node(cpu_buffer->cpu)); |
e4c2ce82 SR |
253 | if (!page) |
254 | goto free_pages; | |
255 | list_add(&page->list, &pages); | |
256 | ||
7a8e76a3 SR |
257 | addr = __get_free_page(GFP_KERNEL); |
258 | if (!addr) | |
259 | goto free_pages; | |
e4c2ce82 | 260 | page->page = (void *)addr; |
7a8e76a3 SR |
261 | } |
262 | ||
263 | list_splice(&pages, head); | |
264 | ||
265 | rb_check_pages(cpu_buffer); | |
266 | ||
267 | return 0; | |
268 | ||
269 | free_pages: | |
270 | list_for_each_entry_safe(page, tmp, &pages, list) { | |
271 | list_del_init(&page->list); | |
ed56829c | 272 | free_buffer_page(page); |
7a8e76a3 SR |
273 | } |
274 | return -ENOMEM; | |
275 | } | |
276 | ||
277 | static struct ring_buffer_per_cpu * | |
278 | rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu) | |
279 | { | |
280 | struct ring_buffer_per_cpu *cpu_buffer; | |
e4c2ce82 | 281 | struct buffer_page *page; |
d769041f | 282 | unsigned long addr; |
7a8e76a3 SR |
283 | int ret; |
284 | ||
285 | cpu_buffer = kzalloc_node(ALIGN(sizeof(*cpu_buffer), cache_line_size()), | |
286 | GFP_KERNEL, cpu_to_node(cpu)); | |
287 | if (!cpu_buffer) | |
288 | return NULL; | |
289 | ||
290 | cpu_buffer->cpu = cpu; | |
291 | cpu_buffer->buffer = buffer; | |
292 | spin_lock_init(&cpu_buffer->lock); | |
293 | INIT_LIST_HEAD(&cpu_buffer->pages); | |
294 | ||
e4c2ce82 SR |
295 | page = kzalloc_node(ALIGN(sizeof(*page), cache_line_size()), |
296 | GFP_KERNEL, cpu_to_node(cpu)); | |
297 | if (!page) | |
298 | goto fail_free_buffer; | |
299 | ||
300 | cpu_buffer->reader_page = page; | |
d769041f SR |
301 | addr = __get_free_page(GFP_KERNEL); |
302 | if (!addr) | |
e4c2ce82 SR |
303 | goto fail_free_reader; |
304 | page->page = (void *)addr; | |
305 | ||
d769041f | 306 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); |
d769041f | 307 | |
7a8e76a3 SR |
308 | ret = rb_allocate_pages(cpu_buffer, buffer->pages); |
309 | if (ret < 0) | |
d769041f | 310 | goto fail_free_reader; |
7a8e76a3 SR |
311 | |
312 | cpu_buffer->head_page | |
313 | = list_entry(cpu_buffer->pages.next, struct buffer_page, list); | |
bf41a158 | 314 | cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; |
7a8e76a3 SR |
315 | |
316 | return cpu_buffer; | |
317 | ||
d769041f SR |
318 | fail_free_reader: |
319 | free_buffer_page(cpu_buffer->reader_page); | |
320 | ||
7a8e76a3 SR |
321 | fail_free_buffer: |
322 | kfree(cpu_buffer); | |
323 | return NULL; | |
324 | } | |
325 | ||
326 | static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) | |
327 | { | |
328 | struct list_head *head = &cpu_buffer->pages; | |
329 | struct buffer_page *page, *tmp; | |
330 | ||
d769041f SR |
331 | list_del_init(&cpu_buffer->reader_page->list); |
332 | free_buffer_page(cpu_buffer->reader_page); | |
333 | ||
7a8e76a3 SR |
334 | list_for_each_entry_safe(page, tmp, head, list) { |
335 | list_del_init(&page->list); | |
ed56829c | 336 | free_buffer_page(page); |
7a8e76a3 SR |
337 | } |
338 | kfree(cpu_buffer); | |
339 | } | |
340 | ||
a7b13743 SR |
341 | /* |
342 | * Causes compile errors if the struct buffer_page gets bigger | |
343 | * than the struct page. | |
344 | */ | |
345 | extern int ring_buffer_page_too_big(void); | |
346 | ||
7a8e76a3 SR |
347 | /** |
348 | * ring_buffer_alloc - allocate a new ring_buffer | |
349 | * @size: the size in bytes that is needed. | |
350 | * @flags: attributes to set for the ring buffer. | |
351 | * | |
352 | * Currently the only flag that is available is the RB_FL_OVERWRITE | |
353 | * flag. This flag means that the buffer will overwrite old data | |
354 | * when the buffer wraps. If this flag is not set, the buffer will | |
355 | * drop data when the tail hits the head. | |
356 | */ | |
357 | struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags) | |
358 | { | |
359 | struct ring_buffer *buffer; | |
360 | int bsize; | |
361 | int cpu; | |
362 | ||
a7b13743 SR |
363 | /* Paranoid! Optimizes out when all is well */ |
364 | if (sizeof(struct buffer_page) > sizeof(struct page)) | |
365 | ring_buffer_page_too_big(); | |
366 | ||
367 | ||
7a8e76a3 SR |
368 | /* keep it in its own cache line */ |
369 | buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()), | |
370 | GFP_KERNEL); | |
371 | if (!buffer) | |
372 | return NULL; | |
373 | ||
374 | buffer->pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); | |
375 | buffer->flags = flags; | |
376 | ||
377 | /* need at least two pages */ | |
378 | if (buffer->pages == 1) | |
379 | buffer->pages++; | |
380 | ||
381 | buffer->cpumask = cpu_possible_map; | |
382 | buffer->cpus = nr_cpu_ids; | |
383 | ||
384 | bsize = sizeof(void *) * nr_cpu_ids; | |
385 | buffer->buffers = kzalloc(ALIGN(bsize, cache_line_size()), | |
386 | GFP_KERNEL); | |
387 | if (!buffer->buffers) | |
388 | goto fail_free_buffer; | |
389 | ||
390 | for_each_buffer_cpu(buffer, cpu) { | |
391 | buffer->buffers[cpu] = | |
392 | rb_allocate_cpu_buffer(buffer, cpu); | |
393 | if (!buffer->buffers[cpu]) | |
394 | goto fail_free_buffers; | |
395 | } | |
396 | ||
397 | mutex_init(&buffer->mutex); | |
398 | ||
399 | return buffer; | |
400 | ||
401 | fail_free_buffers: | |
402 | for_each_buffer_cpu(buffer, cpu) { | |
403 | if (buffer->buffers[cpu]) | |
404 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
405 | } | |
406 | kfree(buffer->buffers); | |
407 | ||
408 | fail_free_buffer: | |
409 | kfree(buffer); | |
410 | return NULL; | |
411 | } | |
412 | ||
413 | /** | |
414 | * ring_buffer_free - free a ring buffer. | |
415 | * @buffer: the buffer to free. | |
416 | */ | |
417 | void | |
418 | ring_buffer_free(struct ring_buffer *buffer) | |
419 | { | |
420 | int cpu; | |
421 | ||
422 | for_each_buffer_cpu(buffer, cpu) | |
423 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
424 | ||
425 | kfree(buffer); | |
426 | } | |
427 | ||
428 | static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer); | |
429 | ||
430 | static void | |
431 | rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages) | |
432 | { | |
433 | struct buffer_page *page; | |
434 | struct list_head *p; | |
435 | unsigned i; | |
436 | ||
437 | atomic_inc(&cpu_buffer->record_disabled); | |
438 | synchronize_sched(); | |
439 | ||
440 | for (i = 0; i < nr_pages; i++) { | |
441 | BUG_ON(list_empty(&cpu_buffer->pages)); | |
442 | p = cpu_buffer->pages.next; | |
443 | page = list_entry(p, struct buffer_page, list); | |
444 | list_del_init(&page->list); | |
ed56829c | 445 | free_buffer_page(page); |
7a8e76a3 SR |
446 | } |
447 | BUG_ON(list_empty(&cpu_buffer->pages)); | |
448 | ||
449 | rb_reset_cpu(cpu_buffer); | |
450 | ||
451 | rb_check_pages(cpu_buffer); | |
452 | ||
453 | atomic_dec(&cpu_buffer->record_disabled); | |
454 | ||
455 | } | |
456 | ||
457 | static void | |
458 | rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer, | |
459 | struct list_head *pages, unsigned nr_pages) | |
460 | { | |
461 | struct buffer_page *page; | |
462 | struct list_head *p; | |
463 | unsigned i; | |
464 | ||
465 | atomic_inc(&cpu_buffer->record_disabled); | |
466 | synchronize_sched(); | |
467 | ||
468 | for (i = 0; i < nr_pages; i++) { | |
469 | BUG_ON(list_empty(pages)); | |
470 | p = pages->next; | |
471 | page = list_entry(p, struct buffer_page, list); | |
472 | list_del_init(&page->list); | |
473 | list_add_tail(&page->list, &cpu_buffer->pages); | |
474 | } | |
475 | rb_reset_cpu(cpu_buffer); | |
476 | ||
477 | rb_check_pages(cpu_buffer); | |
478 | ||
479 | atomic_dec(&cpu_buffer->record_disabled); | |
480 | } | |
481 | ||
482 | /** | |
483 | * ring_buffer_resize - resize the ring buffer | |
484 | * @buffer: the buffer to resize. | |
485 | * @size: the new size. | |
486 | * | |
487 | * The tracer is responsible for making sure that the buffer is | |
488 | * not being used while changing the size. | |
489 | * Note: We may be able to change the above requirement by using | |
490 | * RCU synchronizations. | |
491 | * | |
492 | * Minimum size is 2 * BUF_PAGE_SIZE. | |
493 | * | |
494 | * Returns -1 on failure. | |
495 | */ | |
496 | int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size) | |
497 | { | |
498 | struct ring_buffer_per_cpu *cpu_buffer; | |
499 | unsigned nr_pages, rm_pages, new_pages; | |
500 | struct buffer_page *page, *tmp; | |
501 | unsigned long buffer_size; | |
502 | unsigned long addr; | |
503 | LIST_HEAD(pages); | |
504 | int i, cpu; | |
505 | ||
506 | size = DIV_ROUND_UP(size, BUF_PAGE_SIZE); | |
507 | size *= BUF_PAGE_SIZE; | |
508 | buffer_size = buffer->pages * BUF_PAGE_SIZE; | |
509 | ||
510 | /* we need a minimum of two pages */ | |
511 | if (size < BUF_PAGE_SIZE * 2) | |
512 | size = BUF_PAGE_SIZE * 2; | |
513 | ||
514 | if (size == buffer_size) | |
515 | return size; | |
516 | ||
517 | mutex_lock(&buffer->mutex); | |
518 | ||
519 | nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); | |
520 | ||
521 | if (size < buffer_size) { | |
522 | ||
523 | /* easy case, just free pages */ | |
524 | BUG_ON(nr_pages >= buffer->pages); | |
525 | ||
526 | rm_pages = buffer->pages - nr_pages; | |
527 | ||
528 | for_each_buffer_cpu(buffer, cpu) { | |
529 | cpu_buffer = buffer->buffers[cpu]; | |
530 | rb_remove_pages(cpu_buffer, rm_pages); | |
531 | } | |
532 | goto out; | |
533 | } | |
534 | ||
535 | /* | |
536 | * This is a bit more difficult. We only want to add pages | |
537 | * when we can allocate enough for all CPUs. We do this | |
538 | * by allocating all the pages and storing them on a local | |
539 | * link list. If we succeed in our allocation, then we | |
540 | * add these pages to the cpu_buffers. Otherwise we just free | |
541 | * them all and return -ENOMEM; | |
542 | */ | |
543 | BUG_ON(nr_pages <= buffer->pages); | |
544 | new_pages = nr_pages - buffer->pages; | |
545 | ||
546 | for_each_buffer_cpu(buffer, cpu) { | |
547 | for (i = 0; i < new_pages; i++) { | |
e4c2ce82 SR |
548 | page = kzalloc_node(ALIGN(sizeof(*page), |
549 | cache_line_size()), | |
550 | GFP_KERNEL, cpu_to_node(cpu)); | |
551 | if (!page) | |
552 | goto free_pages; | |
553 | list_add(&page->list, &pages); | |
7a8e76a3 SR |
554 | addr = __get_free_page(GFP_KERNEL); |
555 | if (!addr) | |
556 | goto free_pages; | |
e4c2ce82 | 557 | page->page = (void *)addr; |
7a8e76a3 SR |
558 | } |
559 | } | |
560 | ||
561 | for_each_buffer_cpu(buffer, cpu) { | |
562 | cpu_buffer = buffer->buffers[cpu]; | |
563 | rb_insert_pages(cpu_buffer, &pages, new_pages); | |
564 | } | |
565 | ||
566 | BUG_ON(!list_empty(&pages)); | |
567 | ||
568 | out: | |
569 | buffer->pages = nr_pages; | |
570 | mutex_unlock(&buffer->mutex); | |
571 | ||
572 | return size; | |
573 | ||
574 | free_pages: | |
575 | list_for_each_entry_safe(page, tmp, &pages, list) { | |
576 | list_del_init(&page->list); | |
ed56829c | 577 | free_buffer_page(page); |
7a8e76a3 SR |
578 | } |
579 | return -ENOMEM; | |
580 | } | |
581 | ||
7a8e76a3 SR |
582 | static inline int rb_null_event(struct ring_buffer_event *event) |
583 | { | |
584 | return event->type == RINGBUF_TYPE_PADDING; | |
585 | } | |
586 | ||
6f807acd | 587 | static inline void *__rb_page_index(struct buffer_page *page, unsigned index) |
7a8e76a3 | 588 | { |
e4c2ce82 | 589 | return page->page + index; |
7a8e76a3 SR |
590 | } |
591 | ||
592 | static inline struct ring_buffer_event * | |
d769041f | 593 | rb_reader_event(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 594 | { |
6f807acd SR |
595 | return __rb_page_index(cpu_buffer->reader_page, |
596 | cpu_buffer->reader_page->read); | |
597 | } | |
598 | ||
599 | static inline struct ring_buffer_event * | |
600 | rb_head_event(struct ring_buffer_per_cpu *cpu_buffer) | |
601 | { | |
602 | return __rb_page_index(cpu_buffer->head_page, | |
603 | cpu_buffer->head_page->read); | |
7a8e76a3 SR |
604 | } |
605 | ||
606 | static inline struct ring_buffer_event * | |
607 | rb_iter_head_event(struct ring_buffer_iter *iter) | |
608 | { | |
6f807acd | 609 | return __rb_page_index(iter->head_page, iter->head); |
7a8e76a3 SR |
610 | } |
611 | ||
bf41a158 SR |
612 | static inline unsigned rb_page_write(struct buffer_page *bpage) |
613 | { | |
614 | return local_read(&bpage->write); | |
615 | } | |
616 | ||
617 | static inline unsigned rb_page_commit(struct buffer_page *bpage) | |
618 | { | |
619 | return local_read(&bpage->commit); | |
620 | } | |
621 | ||
622 | /* Size is determined by what has been commited */ | |
623 | static inline unsigned rb_page_size(struct buffer_page *bpage) | |
624 | { | |
625 | return rb_page_commit(bpage); | |
626 | } | |
627 | ||
628 | static inline unsigned | |
629 | rb_commit_index(struct ring_buffer_per_cpu *cpu_buffer) | |
630 | { | |
631 | return rb_page_commit(cpu_buffer->commit_page); | |
632 | } | |
633 | ||
634 | static inline unsigned rb_head_size(struct ring_buffer_per_cpu *cpu_buffer) | |
635 | { | |
636 | return rb_page_commit(cpu_buffer->head_page); | |
637 | } | |
638 | ||
7a8e76a3 SR |
639 | /* |
640 | * When the tail hits the head and the buffer is in overwrite mode, | |
641 | * the head jumps to the next page and all content on the previous | |
642 | * page is discarded. But before doing so, we update the overrun | |
643 | * variable of the buffer. | |
644 | */ | |
645 | static void rb_update_overflow(struct ring_buffer_per_cpu *cpu_buffer) | |
646 | { | |
647 | struct ring_buffer_event *event; | |
648 | unsigned long head; | |
649 | ||
650 | for (head = 0; head < rb_head_size(cpu_buffer); | |
651 | head += rb_event_length(event)) { | |
652 | ||
6f807acd | 653 | event = __rb_page_index(cpu_buffer->head_page, head); |
7a8e76a3 SR |
654 | BUG_ON(rb_null_event(event)); |
655 | /* Only count data entries */ | |
656 | if (event->type != RINGBUF_TYPE_DATA) | |
657 | continue; | |
658 | cpu_buffer->overrun++; | |
659 | cpu_buffer->entries--; | |
660 | } | |
661 | } | |
662 | ||
663 | static inline void rb_inc_page(struct ring_buffer_per_cpu *cpu_buffer, | |
664 | struct buffer_page **page) | |
665 | { | |
666 | struct list_head *p = (*page)->list.next; | |
667 | ||
668 | if (p == &cpu_buffer->pages) | |
669 | p = p->next; | |
670 | ||
671 | *page = list_entry(p, struct buffer_page, list); | |
672 | } | |
673 | ||
bf41a158 SR |
674 | static inline unsigned |
675 | rb_event_index(struct ring_buffer_event *event) | |
676 | { | |
677 | unsigned long addr = (unsigned long)event; | |
678 | ||
679 | return (addr & ~PAGE_MASK) - (PAGE_SIZE - BUF_PAGE_SIZE); | |
680 | } | |
681 | ||
682 | static inline int | |
683 | rb_is_commit(struct ring_buffer_per_cpu *cpu_buffer, | |
684 | struct ring_buffer_event *event) | |
685 | { | |
686 | unsigned long addr = (unsigned long)event; | |
687 | unsigned long index; | |
688 | ||
689 | index = rb_event_index(event); | |
690 | addr &= PAGE_MASK; | |
691 | ||
692 | return cpu_buffer->commit_page->page == (void *)addr && | |
693 | rb_commit_index(cpu_buffer) == index; | |
694 | } | |
695 | ||
7a8e76a3 | 696 | static inline void |
bf41a158 SR |
697 | rb_set_commit_event(struct ring_buffer_per_cpu *cpu_buffer, |
698 | struct ring_buffer_event *event) | |
7a8e76a3 | 699 | { |
bf41a158 SR |
700 | unsigned long addr = (unsigned long)event; |
701 | unsigned long index; | |
702 | ||
703 | index = rb_event_index(event); | |
704 | addr &= PAGE_MASK; | |
705 | ||
706 | while (cpu_buffer->commit_page->page != (void *)addr) { | |
707 | RB_WARN_ON(cpu_buffer, | |
708 | cpu_buffer->commit_page == cpu_buffer->tail_page); | |
709 | cpu_buffer->commit_page->commit = | |
710 | cpu_buffer->commit_page->write; | |
711 | rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); | |
712 | cpu_buffer->write_stamp = cpu_buffer->commit_page->time_stamp; | |
713 | } | |
714 | ||
715 | /* Now set the commit to the event's index */ | |
716 | local_set(&cpu_buffer->commit_page->commit, index); | |
7a8e76a3 SR |
717 | } |
718 | ||
bf41a158 SR |
719 | static inline void |
720 | rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) | |
7a8e76a3 | 721 | { |
bf41a158 SR |
722 | /* |
723 | * We only race with interrupts and NMIs on this CPU. | |
724 | * If we own the commit event, then we can commit | |
725 | * all others that interrupted us, since the interruptions | |
726 | * are in stack format (they finish before they come | |
727 | * back to us). This allows us to do a simple loop to | |
728 | * assign the commit to the tail. | |
729 | */ | |
730 | while (cpu_buffer->commit_page != cpu_buffer->tail_page) { | |
731 | cpu_buffer->commit_page->commit = | |
732 | cpu_buffer->commit_page->write; | |
733 | rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); | |
734 | cpu_buffer->write_stamp = cpu_buffer->commit_page->time_stamp; | |
735 | /* add barrier to keep gcc from optimizing too much */ | |
736 | barrier(); | |
737 | } | |
738 | while (rb_commit_index(cpu_buffer) != | |
739 | rb_page_write(cpu_buffer->commit_page)) { | |
740 | cpu_buffer->commit_page->commit = | |
741 | cpu_buffer->commit_page->write; | |
742 | barrier(); | |
743 | } | |
7a8e76a3 SR |
744 | } |
745 | ||
d769041f | 746 | static void rb_reset_reader_page(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 747 | { |
d769041f | 748 | cpu_buffer->read_stamp = cpu_buffer->reader_page->time_stamp; |
6f807acd | 749 | cpu_buffer->reader_page->read = 0; |
d769041f SR |
750 | } |
751 | ||
752 | static inline void rb_inc_iter(struct ring_buffer_iter *iter) | |
753 | { | |
754 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
755 | ||
756 | /* | |
757 | * The iterator could be on the reader page (it starts there). | |
758 | * But the head could have moved, since the reader was | |
759 | * found. Check for this case and assign the iterator | |
760 | * to the head page instead of next. | |
761 | */ | |
762 | if (iter->head_page == cpu_buffer->reader_page) | |
763 | iter->head_page = cpu_buffer->head_page; | |
764 | else | |
765 | rb_inc_page(cpu_buffer, &iter->head_page); | |
766 | ||
7a8e76a3 SR |
767 | iter->read_stamp = iter->head_page->time_stamp; |
768 | iter->head = 0; | |
769 | } | |
770 | ||
771 | /** | |
772 | * ring_buffer_update_event - update event type and data | |
773 | * @event: the even to update | |
774 | * @type: the type of event | |
775 | * @length: the size of the event field in the ring buffer | |
776 | * | |
777 | * Update the type and data fields of the event. The length | |
778 | * is the actual size that is written to the ring buffer, | |
779 | * and with this, we can determine what to place into the | |
780 | * data field. | |
781 | */ | |
782 | static inline void | |
783 | rb_update_event(struct ring_buffer_event *event, | |
784 | unsigned type, unsigned length) | |
785 | { | |
786 | event->type = type; | |
787 | ||
788 | switch (type) { | |
789 | ||
790 | case RINGBUF_TYPE_PADDING: | |
791 | break; | |
792 | ||
793 | case RINGBUF_TYPE_TIME_EXTEND: | |
794 | event->len = | |
795 | (RB_LEN_TIME_EXTEND + (RB_ALIGNMENT-1)) | |
796 | >> RB_ALIGNMENT_SHIFT; | |
797 | break; | |
798 | ||
799 | case RINGBUF_TYPE_TIME_STAMP: | |
800 | event->len = | |
801 | (RB_LEN_TIME_STAMP + (RB_ALIGNMENT-1)) | |
802 | >> RB_ALIGNMENT_SHIFT; | |
803 | break; | |
804 | ||
805 | case RINGBUF_TYPE_DATA: | |
806 | length -= RB_EVNT_HDR_SIZE; | |
807 | if (length > RB_MAX_SMALL_DATA) { | |
808 | event->len = 0; | |
809 | event->array[0] = length; | |
810 | } else | |
811 | event->len = | |
812 | (length + (RB_ALIGNMENT-1)) | |
813 | >> RB_ALIGNMENT_SHIFT; | |
814 | break; | |
815 | default: | |
816 | BUG(); | |
817 | } | |
818 | } | |
819 | ||
820 | static inline unsigned rb_calculate_event_length(unsigned length) | |
821 | { | |
822 | struct ring_buffer_event event; /* Used only for sizeof array */ | |
823 | ||
824 | /* zero length can cause confusions */ | |
825 | if (!length) | |
826 | length = 1; | |
827 | ||
828 | if (length > RB_MAX_SMALL_DATA) | |
829 | length += sizeof(event.array[0]); | |
830 | ||
831 | length += RB_EVNT_HDR_SIZE; | |
832 | length = ALIGN(length, RB_ALIGNMENT); | |
833 | ||
834 | return length; | |
835 | } | |
836 | ||
837 | static struct ring_buffer_event * | |
838 | __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, | |
839 | unsigned type, unsigned long length, u64 *ts) | |
840 | { | |
d769041f | 841 | struct buffer_page *tail_page, *head_page, *reader_page; |
bf41a158 | 842 | unsigned long tail, write; |
7a8e76a3 SR |
843 | struct ring_buffer *buffer = cpu_buffer->buffer; |
844 | struct ring_buffer_event *event; | |
bf41a158 | 845 | unsigned long flags; |
7a8e76a3 SR |
846 | |
847 | tail_page = cpu_buffer->tail_page; | |
bf41a158 SR |
848 | write = local_add_return(length, &tail_page->write); |
849 | tail = write - length; | |
7a8e76a3 | 850 | |
bf41a158 SR |
851 | /* See if we shot pass the end of this buffer page */ |
852 | if (write > BUF_PAGE_SIZE) { | |
7a8e76a3 SR |
853 | struct buffer_page *next_page = tail_page; |
854 | ||
bf41a158 SR |
855 | spin_lock_irqsave(&cpu_buffer->lock, flags); |
856 | ||
7a8e76a3 SR |
857 | rb_inc_page(cpu_buffer, &next_page); |
858 | ||
d769041f SR |
859 | head_page = cpu_buffer->head_page; |
860 | reader_page = cpu_buffer->reader_page; | |
861 | ||
862 | /* we grabbed the lock before incrementing */ | |
bf41a158 SR |
863 | RB_WARN_ON(cpu_buffer, next_page == reader_page); |
864 | ||
865 | /* | |
866 | * If for some reason, we had an interrupt storm that made | |
867 | * it all the way around the buffer, bail, and warn | |
868 | * about it. | |
869 | */ | |
870 | if (unlikely(next_page == cpu_buffer->commit_page)) { | |
871 | WARN_ON_ONCE(1); | |
872 | goto out_unlock; | |
873 | } | |
d769041f | 874 | |
7a8e76a3 | 875 | if (next_page == head_page) { |
d769041f | 876 | if (!(buffer->flags & RB_FL_OVERWRITE)) { |
bf41a158 SR |
877 | /* reset write */ |
878 | if (tail <= BUF_PAGE_SIZE) | |
879 | local_set(&tail_page->write, tail); | |
880 | goto out_unlock; | |
d769041f | 881 | } |
7a8e76a3 | 882 | |
bf41a158 SR |
883 | /* tail_page has not moved yet? */ |
884 | if (tail_page == cpu_buffer->tail_page) { | |
885 | /* count overflows */ | |
886 | rb_update_overflow(cpu_buffer); | |
887 | ||
888 | rb_inc_page(cpu_buffer, &head_page); | |
889 | cpu_buffer->head_page = head_page; | |
890 | cpu_buffer->head_page->read = 0; | |
891 | } | |
892 | } | |
7a8e76a3 | 893 | |
bf41a158 SR |
894 | /* |
895 | * If the tail page is still the same as what we think | |
896 | * it is, then it is up to us to update the tail | |
897 | * pointer. | |
898 | */ | |
899 | if (tail_page == cpu_buffer->tail_page) { | |
900 | local_set(&next_page->write, 0); | |
901 | local_set(&next_page->commit, 0); | |
902 | cpu_buffer->tail_page = next_page; | |
903 | ||
904 | /* reread the time stamp */ | |
905 | *ts = ring_buffer_time_stamp(cpu_buffer->cpu); | |
906 | cpu_buffer->tail_page->time_stamp = *ts; | |
7a8e76a3 SR |
907 | } |
908 | ||
bf41a158 SR |
909 | /* |
910 | * The actual tail page has moved forward. | |
911 | */ | |
912 | if (tail < BUF_PAGE_SIZE) { | |
913 | /* Mark the rest of the page with padding */ | |
6f807acd | 914 | event = __rb_page_index(tail_page, tail); |
7a8e76a3 SR |
915 | event->type = RINGBUF_TYPE_PADDING; |
916 | } | |
917 | ||
bf41a158 SR |
918 | if (tail <= BUF_PAGE_SIZE) |
919 | /* Set the write back to the previous setting */ | |
920 | local_set(&tail_page->write, tail); | |
921 | ||
922 | /* | |
923 | * If this was a commit entry that failed, | |
924 | * increment that too | |
925 | */ | |
926 | if (tail_page == cpu_buffer->commit_page && | |
927 | tail == rb_commit_index(cpu_buffer)) { | |
928 | rb_set_commit_to_write(cpu_buffer); | |
929 | } | |
930 | ||
931 | spin_unlock_irqrestore(&cpu_buffer->lock, flags); | |
932 | ||
933 | /* fail and let the caller try again */ | |
934 | return ERR_PTR(-EAGAIN); | |
7a8e76a3 SR |
935 | } |
936 | ||
bf41a158 SR |
937 | /* We reserved something on the buffer */ |
938 | ||
939 | BUG_ON(write > BUF_PAGE_SIZE); | |
7a8e76a3 | 940 | |
6f807acd | 941 | event = __rb_page_index(tail_page, tail); |
7a8e76a3 SR |
942 | rb_update_event(event, type, length); |
943 | ||
bf41a158 SR |
944 | /* |
945 | * If this is a commit and the tail is zero, then update | |
946 | * this page's time stamp. | |
947 | */ | |
948 | if (!tail && rb_is_commit(cpu_buffer, event)) | |
949 | cpu_buffer->commit_page->time_stamp = *ts; | |
950 | ||
7a8e76a3 | 951 | return event; |
bf41a158 SR |
952 | |
953 | out_unlock: | |
954 | spin_unlock_irqrestore(&cpu_buffer->lock, flags); | |
955 | return NULL; | |
7a8e76a3 SR |
956 | } |
957 | ||
958 | static int | |
959 | rb_add_time_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
960 | u64 *ts, u64 *delta) | |
961 | { | |
962 | struct ring_buffer_event *event; | |
963 | static int once; | |
bf41a158 | 964 | int ret; |
7a8e76a3 SR |
965 | |
966 | if (unlikely(*delta > (1ULL << 59) && !once++)) { | |
967 | printk(KERN_WARNING "Delta way too big! %llu" | |
968 | " ts=%llu write stamp = %llu\n", | |
969 | *delta, *ts, cpu_buffer->write_stamp); | |
970 | WARN_ON(1); | |
971 | } | |
972 | ||
973 | /* | |
974 | * The delta is too big, we to add a | |
975 | * new timestamp. | |
976 | */ | |
977 | event = __rb_reserve_next(cpu_buffer, | |
978 | RINGBUF_TYPE_TIME_EXTEND, | |
979 | RB_LEN_TIME_EXTEND, | |
980 | ts); | |
981 | if (!event) | |
bf41a158 | 982 | return -EBUSY; |
7a8e76a3 | 983 | |
bf41a158 SR |
984 | if (PTR_ERR(event) == -EAGAIN) |
985 | return -EAGAIN; | |
986 | ||
987 | /* Only a commited time event can update the write stamp */ | |
988 | if (rb_is_commit(cpu_buffer, event)) { | |
989 | /* | |
990 | * If this is the first on the page, then we need to | |
991 | * update the page itself, and just put in a zero. | |
992 | */ | |
993 | if (rb_event_index(event)) { | |
994 | event->time_delta = *delta & TS_MASK; | |
995 | event->array[0] = *delta >> TS_SHIFT; | |
996 | } else { | |
997 | cpu_buffer->commit_page->time_stamp = *ts; | |
998 | event->time_delta = 0; | |
999 | event->array[0] = 0; | |
1000 | } | |
7a8e76a3 | 1001 | cpu_buffer->write_stamp = *ts; |
bf41a158 SR |
1002 | /* let the caller know this was the commit */ |
1003 | ret = 1; | |
1004 | } else { | |
1005 | /* Darn, this is just wasted space */ | |
1006 | event->time_delta = 0; | |
1007 | event->array[0] = 0; | |
1008 | ret = 0; | |
7a8e76a3 SR |
1009 | } |
1010 | ||
bf41a158 SR |
1011 | *delta = 0; |
1012 | ||
1013 | return ret; | |
7a8e76a3 SR |
1014 | } |
1015 | ||
1016 | static struct ring_buffer_event * | |
1017 | rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer, | |
1018 | unsigned type, unsigned long length) | |
1019 | { | |
1020 | struct ring_buffer_event *event; | |
1021 | u64 ts, delta; | |
bf41a158 | 1022 | int commit = 0; |
7a8e76a3 | 1023 | |
bf41a158 | 1024 | again: |
7a8e76a3 SR |
1025 | ts = ring_buffer_time_stamp(cpu_buffer->cpu); |
1026 | ||
bf41a158 SR |
1027 | /* |
1028 | * Only the first commit can update the timestamp. | |
1029 | * Yes there is a race here. If an interrupt comes in | |
1030 | * just after the conditional and it traces too, then it | |
1031 | * will also check the deltas. More than one timestamp may | |
1032 | * also be made. But only the entry that did the actual | |
1033 | * commit will be something other than zero. | |
1034 | */ | |
1035 | if (cpu_buffer->tail_page == cpu_buffer->commit_page && | |
1036 | rb_page_write(cpu_buffer->tail_page) == | |
1037 | rb_commit_index(cpu_buffer)) { | |
1038 | ||
7a8e76a3 SR |
1039 | delta = ts - cpu_buffer->write_stamp; |
1040 | ||
bf41a158 SR |
1041 | /* make sure this delta is calculated here */ |
1042 | barrier(); | |
1043 | ||
1044 | /* Did the write stamp get updated already? */ | |
1045 | if (unlikely(ts < cpu_buffer->write_stamp)) | |
1046 | goto again; | |
1047 | ||
7a8e76a3 | 1048 | if (test_time_stamp(delta)) { |
7a8e76a3 | 1049 | |
bf41a158 SR |
1050 | commit = rb_add_time_stamp(cpu_buffer, &ts, &delta); |
1051 | ||
1052 | if (commit == -EBUSY) | |
7a8e76a3 | 1053 | return NULL; |
bf41a158 SR |
1054 | |
1055 | if (commit == -EAGAIN) | |
1056 | goto again; | |
1057 | ||
1058 | RB_WARN_ON(cpu_buffer, commit < 0); | |
7a8e76a3 | 1059 | } |
bf41a158 SR |
1060 | } else |
1061 | /* Non commits have zero deltas */ | |
7a8e76a3 | 1062 | delta = 0; |
7a8e76a3 SR |
1063 | |
1064 | event = __rb_reserve_next(cpu_buffer, type, length, &ts); | |
bf41a158 SR |
1065 | if (PTR_ERR(event) == -EAGAIN) |
1066 | goto again; | |
1067 | ||
1068 | if (!event) { | |
1069 | if (unlikely(commit)) | |
1070 | /* | |
1071 | * Ouch! We needed a timestamp and it was commited. But | |
1072 | * we didn't get our event reserved. | |
1073 | */ | |
1074 | rb_set_commit_to_write(cpu_buffer); | |
7a8e76a3 | 1075 | return NULL; |
bf41a158 | 1076 | } |
7a8e76a3 | 1077 | |
bf41a158 SR |
1078 | /* |
1079 | * If the timestamp was commited, make the commit our entry | |
1080 | * now so that we will update it when needed. | |
1081 | */ | |
1082 | if (commit) | |
1083 | rb_set_commit_event(cpu_buffer, event); | |
1084 | else if (!rb_is_commit(cpu_buffer, event)) | |
7a8e76a3 SR |
1085 | delta = 0; |
1086 | ||
1087 | event->time_delta = delta; | |
1088 | ||
1089 | return event; | |
1090 | } | |
1091 | ||
bf41a158 SR |
1092 | static DEFINE_PER_CPU(int, rb_need_resched); |
1093 | ||
7a8e76a3 SR |
1094 | /** |
1095 | * ring_buffer_lock_reserve - reserve a part of the buffer | |
1096 | * @buffer: the ring buffer to reserve from | |
1097 | * @length: the length of the data to reserve (excluding event header) | |
1098 | * @flags: a pointer to save the interrupt flags | |
1099 | * | |
1100 | * Returns a reseverd event on the ring buffer to copy directly to. | |
1101 | * The user of this interface will need to get the body to write into | |
1102 | * and can use the ring_buffer_event_data() interface. | |
1103 | * | |
1104 | * The length is the length of the data needed, not the event length | |
1105 | * which also includes the event header. | |
1106 | * | |
1107 | * Must be paired with ring_buffer_unlock_commit, unless NULL is returned. | |
1108 | * If NULL is returned, then nothing has been allocated or locked. | |
1109 | */ | |
1110 | struct ring_buffer_event * | |
1111 | ring_buffer_lock_reserve(struct ring_buffer *buffer, | |
1112 | unsigned long length, | |
1113 | unsigned long *flags) | |
1114 | { | |
1115 | struct ring_buffer_per_cpu *cpu_buffer; | |
1116 | struct ring_buffer_event *event; | |
bf41a158 | 1117 | int cpu, resched; |
7a8e76a3 SR |
1118 | |
1119 | if (atomic_read(&buffer->record_disabled)) | |
1120 | return NULL; | |
1121 | ||
bf41a158 SR |
1122 | /* If we are tracing schedule, we don't want to recurse */ |
1123 | resched = need_resched(); | |
1124 | preempt_disable_notrace(); | |
1125 | ||
7a8e76a3 SR |
1126 | cpu = raw_smp_processor_id(); |
1127 | ||
1128 | if (!cpu_isset(cpu, buffer->cpumask)) | |
d769041f | 1129 | goto out; |
7a8e76a3 SR |
1130 | |
1131 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 SR |
1132 | |
1133 | if (atomic_read(&cpu_buffer->record_disabled)) | |
d769041f | 1134 | goto out; |
7a8e76a3 SR |
1135 | |
1136 | length = rb_calculate_event_length(length); | |
1137 | if (length > BUF_PAGE_SIZE) | |
bf41a158 | 1138 | goto out; |
7a8e76a3 SR |
1139 | |
1140 | event = rb_reserve_next_event(cpu_buffer, RINGBUF_TYPE_DATA, length); | |
1141 | if (!event) | |
d769041f | 1142 | goto out; |
7a8e76a3 | 1143 | |
bf41a158 SR |
1144 | /* |
1145 | * Need to store resched state on this cpu. | |
1146 | * Only the first needs to. | |
1147 | */ | |
1148 | ||
1149 | if (preempt_count() == 1) | |
1150 | per_cpu(rb_need_resched, cpu) = resched; | |
1151 | ||
7a8e76a3 SR |
1152 | return event; |
1153 | ||
d769041f | 1154 | out: |
bf41a158 SR |
1155 | if (resched) |
1156 | preempt_enable_notrace(); | |
1157 | else | |
1158 | preempt_enable_notrace(); | |
7a8e76a3 SR |
1159 | return NULL; |
1160 | } | |
1161 | ||
1162 | static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, | |
1163 | struct ring_buffer_event *event) | |
1164 | { | |
7a8e76a3 | 1165 | cpu_buffer->entries++; |
bf41a158 SR |
1166 | |
1167 | /* Only process further if we own the commit */ | |
1168 | if (!rb_is_commit(cpu_buffer, event)) | |
1169 | return; | |
1170 | ||
1171 | cpu_buffer->write_stamp += event->time_delta; | |
1172 | ||
1173 | rb_set_commit_to_write(cpu_buffer); | |
7a8e76a3 SR |
1174 | } |
1175 | ||
1176 | /** | |
1177 | * ring_buffer_unlock_commit - commit a reserved | |
1178 | * @buffer: The buffer to commit to | |
1179 | * @event: The event pointer to commit. | |
1180 | * @flags: the interrupt flags received from ring_buffer_lock_reserve. | |
1181 | * | |
1182 | * This commits the data to the ring buffer, and releases any locks held. | |
1183 | * | |
1184 | * Must be paired with ring_buffer_lock_reserve. | |
1185 | */ | |
1186 | int ring_buffer_unlock_commit(struct ring_buffer *buffer, | |
1187 | struct ring_buffer_event *event, | |
1188 | unsigned long flags) | |
1189 | { | |
1190 | struct ring_buffer_per_cpu *cpu_buffer; | |
1191 | int cpu = raw_smp_processor_id(); | |
1192 | ||
1193 | cpu_buffer = buffer->buffers[cpu]; | |
1194 | ||
7a8e76a3 SR |
1195 | rb_commit(cpu_buffer, event); |
1196 | ||
bf41a158 SR |
1197 | /* |
1198 | * Only the last preempt count needs to restore preemption. | |
1199 | */ | |
1200 | if (preempt_count() == 1) { | |
1201 | if (per_cpu(rb_need_resched, cpu)) | |
1202 | preempt_enable_no_resched_notrace(); | |
1203 | else | |
1204 | preempt_enable_notrace(); | |
1205 | } else | |
1206 | preempt_enable_no_resched_notrace(); | |
7a8e76a3 SR |
1207 | |
1208 | return 0; | |
1209 | } | |
1210 | ||
1211 | /** | |
1212 | * ring_buffer_write - write data to the buffer without reserving | |
1213 | * @buffer: The ring buffer to write to. | |
1214 | * @length: The length of the data being written (excluding the event header) | |
1215 | * @data: The data to write to the buffer. | |
1216 | * | |
1217 | * This is like ring_buffer_lock_reserve and ring_buffer_unlock_commit as | |
1218 | * one function. If you already have the data to write to the buffer, it | |
1219 | * may be easier to simply call this function. | |
1220 | * | |
1221 | * Note, like ring_buffer_lock_reserve, the length is the length of the data | |
1222 | * and not the length of the event which would hold the header. | |
1223 | */ | |
1224 | int ring_buffer_write(struct ring_buffer *buffer, | |
1225 | unsigned long length, | |
1226 | void *data) | |
1227 | { | |
1228 | struct ring_buffer_per_cpu *cpu_buffer; | |
1229 | struct ring_buffer_event *event; | |
bf41a158 | 1230 | unsigned long event_length; |
7a8e76a3 SR |
1231 | void *body; |
1232 | int ret = -EBUSY; | |
bf41a158 | 1233 | int cpu, resched; |
7a8e76a3 SR |
1234 | |
1235 | if (atomic_read(&buffer->record_disabled)) | |
1236 | return -EBUSY; | |
1237 | ||
bf41a158 SR |
1238 | resched = need_resched(); |
1239 | preempt_disable_notrace(); | |
1240 | ||
7a8e76a3 SR |
1241 | cpu = raw_smp_processor_id(); |
1242 | ||
1243 | if (!cpu_isset(cpu, buffer->cpumask)) | |
d769041f | 1244 | goto out; |
7a8e76a3 SR |
1245 | |
1246 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 SR |
1247 | |
1248 | if (atomic_read(&cpu_buffer->record_disabled)) | |
1249 | goto out; | |
1250 | ||
1251 | event_length = rb_calculate_event_length(length); | |
1252 | event = rb_reserve_next_event(cpu_buffer, | |
1253 | RINGBUF_TYPE_DATA, event_length); | |
1254 | if (!event) | |
1255 | goto out; | |
1256 | ||
1257 | body = rb_event_data(event); | |
1258 | ||
1259 | memcpy(body, data, length); | |
1260 | ||
1261 | rb_commit(cpu_buffer, event); | |
1262 | ||
1263 | ret = 0; | |
1264 | out: | |
bf41a158 SR |
1265 | if (resched) |
1266 | preempt_enable_no_resched_notrace(); | |
1267 | else | |
1268 | preempt_enable_notrace(); | |
7a8e76a3 SR |
1269 | |
1270 | return ret; | |
1271 | } | |
1272 | ||
bf41a158 SR |
1273 | static inline int rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) |
1274 | { | |
1275 | struct buffer_page *reader = cpu_buffer->reader_page; | |
1276 | struct buffer_page *head = cpu_buffer->head_page; | |
1277 | struct buffer_page *commit = cpu_buffer->commit_page; | |
1278 | ||
1279 | return reader->read == rb_page_commit(reader) && | |
1280 | (commit == reader || | |
1281 | (commit == head && | |
1282 | head->read == rb_page_commit(commit))); | |
1283 | } | |
1284 | ||
7a8e76a3 SR |
1285 | /** |
1286 | * ring_buffer_record_disable - stop all writes into the buffer | |
1287 | * @buffer: The ring buffer to stop writes to. | |
1288 | * | |
1289 | * This prevents all writes to the buffer. Any attempt to write | |
1290 | * to the buffer after this will fail and return NULL. | |
1291 | * | |
1292 | * The caller should call synchronize_sched() after this. | |
1293 | */ | |
1294 | void ring_buffer_record_disable(struct ring_buffer *buffer) | |
1295 | { | |
1296 | atomic_inc(&buffer->record_disabled); | |
1297 | } | |
1298 | ||
1299 | /** | |
1300 | * ring_buffer_record_enable - enable writes to the buffer | |
1301 | * @buffer: The ring buffer to enable writes | |
1302 | * | |
1303 | * Note, multiple disables will need the same number of enables | |
1304 | * to truely enable the writing (much like preempt_disable). | |
1305 | */ | |
1306 | void ring_buffer_record_enable(struct ring_buffer *buffer) | |
1307 | { | |
1308 | atomic_dec(&buffer->record_disabled); | |
1309 | } | |
1310 | ||
1311 | /** | |
1312 | * ring_buffer_record_disable_cpu - stop all writes into the cpu_buffer | |
1313 | * @buffer: The ring buffer to stop writes to. | |
1314 | * @cpu: The CPU buffer to stop | |
1315 | * | |
1316 | * This prevents all writes to the buffer. Any attempt to write | |
1317 | * to the buffer after this will fail and return NULL. | |
1318 | * | |
1319 | * The caller should call synchronize_sched() after this. | |
1320 | */ | |
1321 | void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu) | |
1322 | { | |
1323 | struct ring_buffer_per_cpu *cpu_buffer; | |
1324 | ||
1325 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1326 | return; | |
1327 | ||
1328 | cpu_buffer = buffer->buffers[cpu]; | |
1329 | atomic_inc(&cpu_buffer->record_disabled); | |
1330 | } | |
1331 | ||
1332 | /** | |
1333 | * ring_buffer_record_enable_cpu - enable writes to the buffer | |
1334 | * @buffer: The ring buffer to enable writes | |
1335 | * @cpu: The CPU to enable. | |
1336 | * | |
1337 | * Note, multiple disables will need the same number of enables | |
1338 | * to truely enable the writing (much like preempt_disable). | |
1339 | */ | |
1340 | void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu) | |
1341 | { | |
1342 | struct ring_buffer_per_cpu *cpu_buffer; | |
1343 | ||
1344 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1345 | return; | |
1346 | ||
1347 | cpu_buffer = buffer->buffers[cpu]; | |
1348 | atomic_dec(&cpu_buffer->record_disabled); | |
1349 | } | |
1350 | ||
1351 | /** | |
1352 | * ring_buffer_entries_cpu - get the number of entries in a cpu buffer | |
1353 | * @buffer: The ring buffer | |
1354 | * @cpu: The per CPU buffer to get the entries from. | |
1355 | */ | |
1356 | unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu) | |
1357 | { | |
1358 | struct ring_buffer_per_cpu *cpu_buffer; | |
1359 | ||
1360 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1361 | return 0; | |
1362 | ||
1363 | cpu_buffer = buffer->buffers[cpu]; | |
1364 | return cpu_buffer->entries; | |
1365 | } | |
1366 | ||
1367 | /** | |
1368 | * ring_buffer_overrun_cpu - get the number of overruns in a cpu_buffer | |
1369 | * @buffer: The ring buffer | |
1370 | * @cpu: The per CPU buffer to get the number of overruns from | |
1371 | */ | |
1372 | unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu) | |
1373 | { | |
1374 | struct ring_buffer_per_cpu *cpu_buffer; | |
1375 | ||
1376 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1377 | return 0; | |
1378 | ||
1379 | cpu_buffer = buffer->buffers[cpu]; | |
1380 | return cpu_buffer->overrun; | |
1381 | } | |
1382 | ||
1383 | /** | |
1384 | * ring_buffer_entries - get the number of entries in a buffer | |
1385 | * @buffer: The ring buffer | |
1386 | * | |
1387 | * Returns the total number of entries in the ring buffer | |
1388 | * (all CPU entries) | |
1389 | */ | |
1390 | unsigned long ring_buffer_entries(struct ring_buffer *buffer) | |
1391 | { | |
1392 | struct ring_buffer_per_cpu *cpu_buffer; | |
1393 | unsigned long entries = 0; | |
1394 | int cpu; | |
1395 | ||
1396 | /* if you care about this being correct, lock the buffer */ | |
1397 | for_each_buffer_cpu(buffer, cpu) { | |
1398 | cpu_buffer = buffer->buffers[cpu]; | |
1399 | entries += cpu_buffer->entries; | |
1400 | } | |
1401 | ||
1402 | return entries; | |
1403 | } | |
1404 | ||
1405 | /** | |
1406 | * ring_buffer_overrun_cpu - get the number of overruns in buffer | |
1407 | * @buffer: The ring buffer | |
1408 | * | |
1409 | * Returns the total number of overruns in the ring buffer | |
1410 | * (all CPU entries) | |
1411 | */ | |
1412 | unsigned long ring_buffer_overruns(struct ring_buffer *buffer) | |
1413 | { | |
1414 | struct ring_buffer_per_cpu *cpu_buffer; | |
1415 | unsigned long overruns = 0; | |
1416 | int cpu; | |
1417 | ||
1418 | /* if you care about this being correct, lock the buffer */ | |
1419 | for_each_buffer_cpu(buffer, cpu) { | |
1420 | cpu_buffer = buffer->buffers[cpu]; | |
1421 | overruns += cpu_buffer->overrun; | |
1422 | } | |
1423 | ||
1424 | return overruns; | |
1425 | } | |
1426 | ||
1427 | /** | |
1428 | * ring_buffer_iter_reset - reset an iterator | |
1429 | * @iter: The iterator to reset | |
1430 | * | |
1431 | * Resets the iterator, so that it will start from the beginning | |
1432 | * again. | |
1433 | */ | |
1434 | void ring_buffer_iter_reset(struct ring_buffer_iter *iter) | |
1435 | { | |
1436 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
1437 | ||
d769041f SR |
1438 | /* Iterator usage is expected to have record disabled */ |
1439 | if (list_empty(&cpu_buffer->reader_page->list)) { | |
1440 | iter->head_page = cpu_buffer->head_page; | |
6f807acd | 1441 | iter->head = cpu_buffer->head_page->read; |
d769041f SR |
1442 | } else { |
1443 | iter->head_page = cpu_buffer->reader_page; | |
6f807acd | 1444 | iter->head = cpu_buffer->reader_page->read; |
d769041f SR |
1445 | } |
1446 | if (iter->head) | |
1447 | iter->read_stamp = cpu_buffer->read_stamp; | |
1448 | else | |
1449 | iter->read_stamp = iter->head_page->time_stamp; | |
7a8e76a3 SR |
1450 | } |
1451 | ||
1452 | /** | |
1453 | * ring_buffer_iter_empty - check if an iterator has no more to read | |
1454 | * @iter: The iterator to check | |
1455 | */ | |
1456 | int ring_buffer_iter_empty(struct ring_buffer_iter *iter) | |
1457 | { | |
1458 | struct ring_buffer_per_cpu *cpu_buffer; | |
1459 | ||
1460 | cpu_buffer = iter->cpu_buffer; | |
1461 | ||
bf41a158 SR |
1462 | return iter->head_page == cpu_buffer->commit_page && |
1463 | iter->head == rb_commit_index(cpu_buffer); | |
7a8e76a3 SR |
1464 | } |
1465 | ||
1466 | static void | |
1467 | rb_update_read_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
1468 | struct ring_buffer_event *event) | |
1469 | { | |
1470 | u64 delta; | |
1471 | ||
1472 | switch (event->type) { | |
1473 | case RINGBUF_TYPE_PADDING: | |
1474 | return; | |
1475 | ||
1476 | case RINGBUF_TYPE_TIME_EXTEND: | |
1477 | delta = event->array[0]; | |
1478 | delta <<= TS_SHIFT; | |
1479 | delta += event->time_delta; | |
1480 | cpu_buffer->read_stamp += delta; | |
1481 | return; | |
1482 | ||
1483 | case RINGBUF_TYPE_TIME_STAMP: | |
1484 | /* FIXME: not implemented */ | |
1485 | return; | |
1486 | ||
1487 | case RINGBUF_TYPE_DATA: | |
1488 | cpu_buffer->read_stamp += event->time_delta; | |
1489 | return; | |
1490 | ||
1491 | default: | |
1492 | BUG(); | |
1493 | } | |
1494 | return; | |
1495 | } | |
1496 | ||
1497 | static void | |
1498 | rb_update_iter_read_stamp(struct ring_buffer_iter *iter, | |
1499 | struct ring_buffer_event *event) | |
1500 | { | |
1501 | u64 delta; | |
1502 | ||
1503 | switch (event->type) { | |
1504 | case RINGBUF_TYPE_PADDING: | |
1505 | return; | |
1506 | ||
1507 | case RINGBUF_TYPE_TIME_EXTEND: | |
1508 | delta = event->array[0]; | |
1509 | delta <<= TS_SHIFT; | |
1510 | delta += event->time_delta; | |
1511 | iter->read_stamp += delta; | |
1512 | return; | |
1513 | ||
1514 | case RINGBUF_TYPE_TIME_STAMP: | |
1515 | /* FIXME: not implemented */ | |
1516 | return; | |
1517 | ||
1518 | case RINGBUF_TYPE_DATA: | |
1519 | iter->read_stamp += event->time_delta; | |
1520 | return; | |
1521 | ||
1522 | default: | |
1523 | BUG(); | |
1524 | } | |
1525 | return; | |
1526 | } | |
1527 | ||
d769041f SR |
1528 | static struct buffer_page * |
1529 | rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) | |
7a8e76a3 | 1530 | { |
d769041f SR |
1531 | struct buffer_page *reader = NULL; |
1532 | unsigned long flags; | |
1533 | ||
1534 | spin_lock_irqsave(&cpu_buffer->lock, flags); | |
1535 | ||
1536 | again: | |
1537 | reader = cpu_buffer->reader_page; | |
1538 | ||
1539 | /* If there's more to read, return this page */ | |
bf41a158 | 1540 | if (cpu_buffer->reader_page->read < rb_page_size(reader)) |
d769041f SR |
1541 | goto out; |
1542 | ||
1543 | /* Never should we have an index greater than the size */ | |
bf41a158 SR |
1544 | RB_WARN_ON(cpu_buffer, |
1545 | cpu_buffer->reader_page->read > rb_page_size(reader)); | |
d769041f SR |
1546 | |
1547 | /* check if we caught up to the tail */ | |
1548 | reader = NULL; | |
bf41a158 | 1549 | if (cpu_buffer->commit_page == cpu_buffer->reader_page) |
d769041f | 1550 | goto out; |
7a8e76a3 SR |
1551 | |
1552 | /* | |
d769041f SR |
1553 | * Splice the empty reader page into the list around the head. |
1554 | * Reset the reader page to size zero. | |
7a8e76a3 | 1555 | */ |
7a8e76a3 | 1556 | |
d769041f SR |
1557 | reader = cpu_buffer->head_page; |
1558 | cpu_buffer->reader_page->list.next = reader->list.next; | |
1559 | cpu_buffer->reader_page->list.prev = reader->list.prev; | |
bf41a158 SR |
1560 | |
1561 | local_set(&cpu_buffer->reader_page->write, 0); | |
1562 | local_set(&cpu_buffer->reader_page->commit, 0); | |
7a8e76a3 | 1563 | |
d769041f SR |
1564 | /* Make the reader page now replace the head */ |
1565 | reader->list.prev->next = &cpu_buffer->reader_page->list; | |
1566 | reader->list.next->prev = &cpu_buffer->reader_page->list; | |
7a8e76a3 SR |
1567 | |
1568 | /* | |
d769041f SR |
1569 | * If the tail is on the reader, then we must set the head |
1570 | * to the inserted page, otherwise we set it one before. | |
7a8e76a3 | 1571 | */ |
d769041f | 1572 | cpu_buffer->head_page = cpu_buffer->reader_page; |
7a8e76a3 | 1573 | |
bf41a158 | 1574 | if (cpu_buffer->commit_page != reader) |
d769041f SR |
1575 | rb_inc_page(cpu_buffer, &cpu_buffer->head_page); |
1576 | ||
1577 | /* Finally update the reader page to the new head */ | |
1578 | cpu_buffer->reader_page = reader; | |
1579 | rb_reset_reader_page(cpu_buffer); | |
1580 | ||
1581 | goto again; | |
1582 | ||
1583 | out: | |
1584 | spin_unlock_irqrestore(&cpu_buffer->lock, flags); | |
1585 | ||
1586 | return reader; | |
1587 | } | |
1588 | ||
1589 | static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer) | |
1590 | { | |
1591 | struct ring_buffer_event *event; | |
1592 | struct buffer_page *reader; | |
1593 | unsigned length; | |
1594 | ||
1595 | reader = rb_get_reader_page(cpu_buffer); | |
7a8e76a3 | 1596 | |
d769041f SR |
1597 | /* This function should not be called when buffer is empty */ |
1598 | BUG_ON(!reader); | |
7a8e76a3 | 1599 | |
d769041f SR |
1600 | event = rb_reader_event(cpu_buffer); |
1601 | ||
1602 | if (event->type == RINGBUF_TYPE_DATA) | |
1603 | cpu_buffer->entries--; | |
1604 | ||
1605 | rb_update_read_stamp(cpu_buffer, event); | |
1606 | ||
1607 | length = rb_event_length(event); | |
6f807acd | 1608 | cpu_buffer->reader_page->read += length; |
7a8e76a3 SR |
1609 | } |
1610 | ||
1611 | static void rb_advance_iter(struct ring_buffer_iter *iter) | |
1612 | { | |
1613 | struct ring_buffer *buffer; | |
1614 | struct ring_buffer_per_cpu *cpu_buffer; | |
1615 | struct ring_buffer_event *event; | |
1616 | unsigned length; | |
1617 | ||
1618 | cpu_buffer = iter->cpu_buffer; | |
1619 | buffer = cpu_buffer->buffer; | |
1620 | ||
1621 | /* | |
1622 | * Check if we are at the end of the buffer. | |
1623 | */ | |
bf41a158 SR |
1624 | if (iter->head >= rb_page_size(iter->head_page)) { |
1625 | BUG_ON(iter->head_page == cpu_buffer->commit_page); | |
d769041f | 1626 | rb_inc_iter(iter); |
7a8e76a3 SR |
1627 | return; |
1628 | } | |
1629 | ||
1630 | event = rb_iter_head_event(iter); | |
1631 | ||
1632 | length = rb_event_length(event); | |
1633 | ||
1634 | /* | |
1635 | * This should not be called to advance the header if we are | |
1636 | * at the tail of the buffer. | |
1637 | */ | |
bf41a158 SR |
1638 | BUG_ON((iter->head_page == cpu_buffer->commit_page) && |
1639 | (iter->head + length > rb_commit_index(cpu_buffer))); | |
7a8e76a3 SR |
1640 | |
1641 | rb_update_iter_read_stamp(iter, event); | |
1642 | ||
1643 | iter->head += length; | |
1644 | ||
1645 | /* check for end of page padding */ | |
bf41a158 SR |
1646 | if ((iter->head >= rb_page_size(iter->head_page)) && |
1647 | (iter->head_page != cpu_buffer->commit_page)) | |
7a8e76a3 SR |
1648 | rb_advance_iter(iter); |
1649 | } | |
1650 | ||
1651 | /** | |
1652 | * ring_buffer_peek - peek at the next event to be read | |
1653 | * @buffer: The ring buffer to read | |
1654 | * @cpu: The cpu to peak at | |
1655 | * @ts: The timestamp counter of this event. | |
1656 | * | |
1657 | * This will return the event that will be read next, but does | |
1658 | * not consume the data. | |
1659 | */ | |
1660 | struct ring_buffer_event * | |
1661 | ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) | |
1662 | { | |
1663 | struct ring_buffer_per_cpu *cpu_buffer; | |
1664 | struct ring_buffer_event *event; | |
d769041f | 1665 | struct buffer_page *reader; |
7a8e76a3 SR |
1666 | |
1667 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1668 | return NULL; | |
1669 | ||
1670 | cpu_buffer = buffer->buffers[cpu]; | |
1671 | ||
1672 | again: | |
d769041f SR |
1673 | reader = rb_get_reader_page(cpu_buffer); |
1674 | if (!reader) | |
7a8e76a3 SR |
1675 | return NULL; |
1676 | ||
d769041f | 1677 | event = rb_reader_event(cpu_buffer); |
7a8e76a3 SR |
1678 | |
1679 | switch (event->type) { | |
1680 | case RINGBUF_TYPE_PADDING: | |
bf41a158 | 1681 | RB_WARN_ON(cpu_buffer, 1); |
d769041f SR |
1682 | rb_advance_reader(cpu_buffer); |
1683 | return NULL; | |
7a8e76a3 SR |
1684 | |
1685 | case RINGBUF_TYPE_TIME_EXTEND: | |
1686 | /* Internal data, OK to advance */ | |
d769041f | 1687 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
1688 | goto again; |
1689 | ||
1690 | case RINGBUF_TYPE_TIME_STAMP: | |
1691 | /* FIXME: not implemented */ | |
d769041f | 1692 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
1693 | goto again; |
1694 | ||
1695 | case RINGBUF_TYPE_DATA: | |
1696 | if (ts) { | |
1697 | *ts = cpu_buffer->read_stamp + event->time_delta; | |
1698 | ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts); | |
1699 | } | |
1700 | return event; | |
1701 | ||
1702 | default: | |
1703 | BUG(); | |
1704 | } | |
1705 | ||
1706 | return NULL; | |
1707 | } | |
1708 | ||
1709 | /** | |
1710 | * ring_buffer_iter_peek - peek at the next event to be read | |
1711 | * @iter: The ring buffer iterator | |
1712 | * @ts: The timestamp counter of this event. | |
1713 | * | |
1714 | * This will return the event that will be read next, but does | |
1715 | * not increment the iterator. | |
1716 | */ | |
1717 | struct ring_buffer_event * | |
1718 | ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) | |
1719 | { | |
1720 | struct ring_buffer *buffer; | |
1721 | struct ring_buffer_per_cpu *cpu_buffer; | |
1722 | struct ring_buffer_event *event; | |
1723 | ||
1724 | if (ring_buffer_iter_empty(iter)) | |
1725 | return NULL; | |
1726 | ||
1727 | cpu_buffer = iter->cpu_buffer; | |
1728 | buffer = cpu_buffer->buffer; | |
1729 | ||
1730 | again: | |
1731 | if (rb_per_cpu_empty(cpu_buffer)) | |
1732 | return NULL; | |
1733 | ||
1734 | event = rb_iter_head_event(iter); | |
1735 | ||
1736 | switch (event->type) { | |
1737 | case RINGBUF_TYPE_PADDING: | |
d769041f | 1738 | rb_inc_iter(iter); |
7a8e76a3 SR |
1739 | goto again; |
1740 | ||
1741 | case RINGBUF_TYPE_TIME_EXTEND: | |
1742 | /* Internal data, OK to advance */ | |
1743 | rb_advance_iter(iter); | |
1744 | goto again; | |
1745 | ||
1746 | case RINGBUF_TYPE_TIME_STAMP: | |
1747 | /* FIXME: not implemented */ | |
1748 | rb_advance_iter(iter); | |
1749 | goto again; | |
1750 | ||
1751 | case RINGBUF_TYPE_DATA: | |
1752 | if (ts) { | |
1753 | *ts = iter->read_stamp + event->time_delta; | |
1754 | ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts); | |
1755 | } | |
1756 | return event; | |
1757 | ||
1758 | default: | |
1759 | BUG(); | |
1760 | } | |
1761 | ||
1762 | return NULL; | |
1763 | } | |
1764 | ||
1765 | /** | |
1766 | * ring_buffer_consume - return an event and consume it | |
1767 | * @buffer: The ring buffer to get the next event from | |
1768 | * | |
1769 | * Returns the next event in the ring buffer, and that event is consumed. | |
1770 | * Meaning, that sequential reads will keep returning a different event, | |
1771 | * and eventually empty the ring buffer if the producer is slower. | |
1772 | */ | |
1773 | struct ring_buffer_event * | |
1774 | ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts) | |
1775 | { | |
1776 | struct ring_buffer_per_cpu *cpu_buffer; | |
1777 | struct ring_buffer_event *event; | |
1778 | ||
1779 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1780 | return NULL; | |
1781 | ||
1782 | event = ring_buffer_peek(buffer, cpu, ts); | |
1783 | if (!event) | |
1784 | return NULL; | |
1785 | ||
1786 | cpu_buffer = buffer->buffers[cpu]; | |
d769041f | 1787 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
1788 | |
1789 | return event; | |
1790 | } | |
1791 | ||
1792 | /** | |
1793 | * ring_buffer_read_start - start a non consuming read of the buffer | |
1794 | * @buffer: The ring buffer to read from | |
1795 | * @cpu: The cpu buffer to iterate over | |
1796 | * | |
1797 | * This starts up an iteration through the buffer. It also disables | |
1798 | * the recording to the buffer until the reading is finished. | |
1799 | * This prevents the reading from being corrupted. This is not | |
1800 | * a consuming read, so a producer is not expected. | |
1801 | * | |
1802 | * Must be paired with ring_buffer_finish. | |
1803 | */ | |
1804 | struct ring_buffer_iter * | |
1805 | ring_buffer_read_start(struct ring_buffer *buffer, int cpu) | |
1806 | { | |
1807 | struct ring_buffer_per_cpu *cpu_buffer; | |
1808 | struct ring_buffer_iter *iter; | |
d769041f | 1809 | unsigned long flags; |
7a8e76a3 SR |
1810 | |
1811 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1812 | return NULL; | |
1813 | ||
1814 | iter = kmalloc(sizeof(*iter), GFP_KERNEL); | |
1815 | if (!iter) | |
1816 | return NULL; | |
1817 | ||
1818 | cpu_buffer = buffer->buffers[cpu]; | |
1819 | ||
1820 | iter->cpu_buffer = cpu_buffer; | |
1821 | ||
1822 | atomic_inc(&cpu_buffer->record_disabled); | |
1823 | synchronize_sched(); | |
1824 | ||
d769041f SR |
1825 | spin_lock_irqsave(&cpu_buffer->lock, flags); |
1826 | ring_buffer_iter_reset(iter); | |
1827 | spin_unlock_irqrestore(&cpu_buffer->lock, flags); | |
7a8e76a3 SR |
1828 | |
1829 | return iter; | |
1830 | } | |
1831 | ||
1832 | /** | |
1833 | * ring_buffer_finish - finish reading the iterator of the buffer | |
1834 | * @iter: The iterator retrieved by ring_buffer_start | |
1835 | * | |
1836 | * This re-enables the recording to the buffer, and frees the | |
1837 | * iterator. | |
1838 | */ | |
1839 | void | |
1840 | ring_buffer_read_finish(struct ring_buffer_iter *iter) | |
1841 | { | |
1842 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
1843 | ||
1844 | atomic_dec(&cpu_buffer->record_disabled); | |
1845 | kfree(iter); | |
1846 | } | |
1847 | ||
1848 | /** | |
1849 | * ring_buffer_read - read the next item in the ring buffer by the iterator | |
1850 | * @iter: The ring buffer iterator | |
1851 | * @ts: The time stamp of the event read. | |
1852 | * | |
1853 | * This reads the next event in the ring buffer and increments the iterator. | |
1854 | */ | |
1855 | struct ring_buffer_event * | |
1856 | ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) | |
1857 | { | |
1858 | struct ring_buffer_event *event; | |
1859 | ||
1860 | event = ring_buffer_iter_peek(iter, ts); | |
1861 | if (!event) | |
1862 | return NULL; | |
1863 | ||
1864 | rb_advance_iter(iter); | |
1865 | ||
1866 | return event; | |
1867 | } | |
1868 | ||
1869 | /** | |
1870 | * ring_buffer_size - return the size of the ring buffer (in bytes) | |
1871 | * @buffer: The ring buffer. | |
1872 | */ | |
1873 | unsigned long ring_buffer_size(struct ring_buffer *buffer) | |
1874 | { | |
1875 | return BUF_PAGE_SIZE * buffer->pages; | |
1876 | } | |
1877 | ||
1878 | static void | |
1879 | rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) | |
1880 | { | |
1881 | cpu_buffer->head_page | |
1882 | = list_entry(cpu_buffer->pages.next, struct buffer_page, list); | |
bf41a158 SR |
1883 | local_set(&cpu_buffer->head_page->write, 0); |
1884 | local_set(&cpu_buffer->head_page->commit, 0); | |
d769041f | 1885 | |
6f807acd | 1886 | cpu_buffer->head_page->read = 0; |
bf41a158 SR |
1887 | |
1888 | cpu_buffer->tail_page = cpu_buffer->head_page; | |
1889 | cpu_buffer->commit_page = cpu_buffer->head_page; | |
1890 | ||
1891 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); | |
1892 | local_set(&cpu_buffer->reader_page->write, 0); | |
1893 | local_set(&cpu_buffer->reader_page->commit, 0); | |
6f807acd | 1894 | cpu_buffer->reader_page->read = 0; |
7a8e76a3 | 1895 | |
7a8e76a3 SR |
1896 | cpu_buffer->overrun = 0; |
1897 | cpu_buffer->entries = 0; | |
1898 | } | |
1899 | ||
1900 | /** | |
1901 | * ring_buffer_reset_cpu - reset a ring buffer per CPU buffer | |
1902 | * @buffer: The ring buffer to reset a per cpu buffer of | |
1903 | * @cpu: The CPU buffer to be reset | |
1904 | */ | |
1905 | void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) | |
1906 | { | |
1907 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
1908 | unsigned long flags; | |
1909 | ||
1910 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1911 | return; | |
1912 | ||
d769041f | 1913 | spin_lock_irqsave(&cpu_buffer->lock, flags); |
7a8e76a3 SR |
1914 | |
1915 | rb_reset_cpu(cpu_buffer); | |
1916 | ||
d769041f | 1917 | spin_unlock_irqrestore(&cpu_buffer->lock, flags); |
7a8e76a3 SR |
1918 | } |
1919 | ||
1920 | /** | |
1921 | * ring_buffer_reset - reset a ring buffer | |
1922 | * @buffer: The ring buffer to reset all cpu buffers | |
1923 | */ | |
1924 | void ring_buffer_reset(struct ring_buffer *buffer) | |
1925 | { | |
7a8e76a3 SR |
1926 | int cpu; |
1927 | ||
7a8e76a3 | 1928 | for_each_buffer_cpu(buffer, cpu) |
d769041f | 1929 | ring_buffer_reset_cpu(buffer, cpu); |
7a8e76a3 SR |
1930 | } |
1931 | ||
1932 | /** | |
1933 | * rind_buffer_empty - is the ring buffer empty? | |
1934 | * @buffer: The ring buffer to test | |
1935 | */ | |
1936 | int ring_buffer_empty(struct ring_buffer *buffer) | |
1937 | { | |
1938 | struct ring_buffer_per_cpu *cpu_buffer; | |
1939 | int cpu; | |
1940 | ||
1941 | /* yes this is racy, but if you don't like the race, lock the buffer */ | |
1942 | for_each_buffer_cpu(buffer, cpu) { | |
1943 | cpu_buffer = buffer->buffers[cpu]; | |
1944 | if (!rb_per_cpu_empty(cpu_buffer)) | |
1945 | return 0; | |
1946 | } | |
1947 | return 1; | |
1948 | } | |
1949 | ||
1950 | /** | |
1951 | * ring_buffer_empty_cpu - is a cpu buffer of a ring buffer empty? | |
1952 | * @buffer: The ring buffer | |
1953 | * @cpu: The CPU buffer to test | |
1954 | */ | |
1955 | int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) | |
1956 | { | |
1957 | struct ring_buffer_per_cpu *cpu_buffer; | |
1958 | ||
1959 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1960 | return 1; | |
1961 | ||
1962 | cpu_buffer = buffer->buffers[cpu]; | |
1963 | return rb_per_cpu_empty(cpu_buffer); | |
1964 | } | |
1965 | ||
1966 | /** | |
1967 | * ring_buffer_swap_cpu - swap a CPU buffer between two ring buffers | |
1968 | * @buffer_a: One buffer to swap with | |
1969 | * @buffer_b: The other buffer to swap with | |
1970 | * | |
1971 | * This function is useful for tracers that want to take a "snapshot" | |
1972 | * of a CPU buffer and has another back up buffer lying around. | |
1973 | * it is expected that the tracer handles the cpu buffer not being | |
1974 | * used at the moment. | |
1975 | */ | |
1976 | int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, | |
1977 | struct ring_buffer *buffer_b, int cpu) | |
1978 | { | |
1979 | struct ring_buffer_per_cpu *cpu_buffer_a; | |
1980 | struct ring_buffer_per_cpu *cpu_buffer_b; | |
1981 | ||
1982 | if (!cpu_isset(cpu, buffer_a->cpumask) || | |
1983 | !cpu_isset(cpu, buffer_b->cpumask)) | |
1984 | return -EINVAL; | |
1985 | ||
1986 | /* At least make sure the two buffers are somewhat the same */ | |
1987 | if (buffer_a->size != buffer_b->size || | |
1988 | buffer_a->pages != buffer_b->pages) | |
1989 | return -EINVAL; | |
1990 | ||
1991 | cpu_buffer_a = buffer_a->buffers[cpu]; | |
1992 | cpu_buffer_b = buffer_b->buffers[cpu]; | |
1993 | ||
1994 | /* | |
1995 | * We can't do a synchronize_sched here because this | |
1996 | * function can be called in atomic context. | |
1997 | * Normally this will be called from the same CPU as cpu. | |
1998 | * If not it's up to the caller to protect this. | |
1999 | */ | |
2000 | atomic_inc(&cpu_buffer_a->record_disabled); | |
2001 | atomic_inc(&cpu_buffer_b->record_disabled); | |
2002 | ||
2003 | buffer_a->buffers[cpu] = cpu_buffer_b; | |
2004 | buffer_b->buffers[cpu] = cpu_buffer_a; | |
2005 | ||
2006 | cpu_buffer_b->buffer = buffer_a; | |
2007 | cpu_buffer_a->buffer = buffer_b; | |
2008 | ||
2009 | atomic_dec(&cpu_buffer_a->record_disabled); | |
2010 | atomic_dec(&cpu_buffer_b->record_disabled); | |
2011 | ||
2012 | return 0; | |
2013 | } | |
2014 |