]>
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 { | |
118 | union { | |
119 | struct { | |
120 | unsigned long flags; /* mandatory */ | |
121 | atomic_t _count; /* mandatory */ | |
122 | u64 time_stamp; /* page time stamp */ | |
123 | unsigned size; /* size of page data */ | |
124 | struct list_head list; /* list of free pages */ | |
125 | }; | |
126 | struct page page; | |
127 | }; | |
128 | }; | |
129 | ||
ed56829c SR |
130 | /* |
131 | * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing | |
132 | * this issue out. | |
133 | */ | |
134 | static inline void free_buffer_page(struct buffer_page *bpage) | |
135 | { | |
136 | reset_page_mapcount(&bpage->page); | |
137 | bpage->page.mapping = NULL; | |
138 | __free_page(&bpage->page); | |
139 | } | |
140 | ||
7a8e76a3 SR |
141 | /* |
142 | * We need to fit the time_stamp delta into 27 bits. | |
143 | */ | |
144 | static inline int test_time_stamp(u64 delta) | |
145 | { | |
146 | if (delta & TS_DELTA_TEST) | |
147 | return 1; | |
148 | return 0; | |
149 | } | |
150 | ||
151 | #define BUF_PAGE_SIZE PAGE_SIZE | |
152 | ||
153 | /* | |
154 | * head_page == tail_page && head == tail then buffer is empty. | |
155 | */ | |
156 | struct ring_buffer_per_cpu { | |
157 | int cpu; | |
158 | struct ring_buffer *buffer; | |
159 | spinlock_t lock; | |
160 | struct lock_class_key lock_key; | |
161 | struct list_head pages; | |
162 | unsigned long head; /* read from head */ | |
163 | unsigned long tail; /* write to tail */ | |
164 | struct buffer_page *head_page; | |
165 | struct buffer_page *tail_page; | |
166 | unsigned long overrun; | |
167 | unsigned long entries; | |
168 | u64 write_stamp; | |
169 | u64 read_stamp; | |
170 | atomic_t record_disabled; | |
171 | }; | |
172 | ||
173 | struct ring_buffer { | |
174 | unsigned long size; | |
175 | unsigned pages; | |
176 | unsigned flags; | |
177 | int cpus; | |
178 | cpumask_t cpumask; | |
179 | atomic_t record_disabled; | |
180 | ||
181 | struct mutex mutex; | |
182 | ||
183 | struct ring_buffer_per_cpu **buffers; | |
184 | }; | |
185 | ||
186 | struct ring_buffer_iter { | |
187 | struct ring_buffer_per_cpu *cpu_buffer; | |
188 | unsigned long head; | |
189 | struct buffer_page *head_page; | |
190 | u64 read_stamp; | |
191 | }; | |
192 | ||
193 | #define RB_WARN_ON(buffer, cond) \ | |
194 | if (unlikely(cond)) { \ | |
195 | atomic_inc(&buffer->record_disabled); \ | |
196 | WARN_ON(1); \ | |
197 | return -1; \ | |
198 | } | |
199 | ||
200 | /** | |
201 | * check_pages - integrity check of buffer pages | |
202 | * @cpu_buffer: CPU buffer with pages to test | |
203 | * | |
204 | * As a safty measure we check to make sure the data pages have not | |
205 | * been corrupted. | |
206 | */ | |
207 | static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) | |
208 | { | |
209 | struct list_head *head = &cpu_buffer->pages; | |
210 | struct buffer_page *page, *tmp; | |
211 | ||
212 | RB_WARN_ON(cpu_buffer, head->next->prev != head); | |
213 | RB_WARN_ON(cpu_buffer, head->prev->next != head); | |
214 | ||
215 | list_for_each_entry_safe(page, tmp, head, list) { | |
216 | RB_WARN_ON(cpu_buffer, page->list.next->prev != &page->list); | |
217 | RB_WARN_ON(cpu_buffer, page->list.prev->next != &page->list); | |
218 | } | |
219 | ||
220 | return 0; | |
221 | } | |
222 | ||
223 | static unsigned rb_head_size(struct ring_buffer_per_cpu *cpu_buffer) | |
224 | { | |
225 | return cpu_buffer->head_page->size; | |
226 | } | |
227 | ||
228 | static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, | |
229 | unsigned nr_pages) | |
230 | { | |
231 | struct list_head *head = &cpu_buffer->pages; | |
232 | struct buffer_page *page, *tmp; | |
233 | unsigned long addr; | |
234 | LIST_HEAD(pages); | |
235 | unsigned i; | |
236 | ||
237 | for (i = 0; i < nr_pages; i++) { | |
238 | addr = __get_free_page(GFP_KERNEL); | |
239 | if (!addr) | |
240 | goto free_pages; | |
241 | page = (struct buffer_page *)virt_to_page(addr); | |
242 | list_add(&page->list, &pages); | |
243 | } | |
244 | ||
245 | list_splice(&pages, head); | |
246 | ||
247 | rb_check_pages(cpu_buffer); | |
248 | ||
249 | return 0; | |
250 | ||
251 | free_pages: | |
252 | list_for_each_entry_safe(page, tmp, &pages, list) { | |
253 | list_del_init(&page->list); | |
ed56829c | 254 | free_buffer_page(page); |
7a8e76a3 SR |
255 | } |
256 | return -ENOMEM; | |
257 | } | |
258 | ||
259 | static struct ring_buffer_per_cpu * | |
260 | rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu) | |
261 | { | |
262 | struct ring_buffer_per_cpu *cpu_buffer; | |
263 | int ret; | |
264 | ||
265 | cpu_buffer = kzalloc_node(ALIGN(sizeof(*cpu_buffer), cache_line_size()), | |
266 | GFP_KERNEL, cpu_to_node(cpu)); | |
267 | if (!cpu_buffer) | |
268 | return NULL; | |
269 | ||
270 | cpu_buffer->cpu = cpu; | |
271 | cpu_buffer->buffer = buffer; | |
272 | spin_lock_init(&cpu_buffer->lock); | |
273 | INIT_LIST_HEAD(&cpu_buffer->pages); | |
274 | ||
275 | ret = rb_allocate_pages(cpu_buffer, buffer->pages); | |
276 | if (ret < 0) | |
277 | goto fail_free_buffer; | |
278 | ||
279 | cpu_buffer->head_page | |
280 | = list_entry(cpu_buffer->pages.next, struct buffer_page, list); | |
281 | cpu_buffer->tail_page | |
282 | = list_entry(cpu_buffer->pages.next, struct buffer_page, list); | |
283 | ||
284 | return cpu_buffer; | |
285 | ||
286 | fail_free_buffer: | |
287 | kfree(cpu_buffer); | |
288 | return NULL; | |
289 | } | |
290 | ||
291 | static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) | |
292 | { | |
293 | struct list_head *head = &cpu_buffer->pages; | |
294 | struct buffer_page *page, *tmp; | |
295 | ||
296 | list_for_each_entry_safe(page, tmp, head, list) { | |
297 | list_del_init(&page->list); | |
ed56829c | 298 | free_buffer_page(page); |
7a8e76a3 SR |
299 | } |
300 | kfree(cpu_buffer); | |
301 | } | |
302 | ||
a7b13743 SR |
303 | /* |
304 | * Causes compile errors if the struct buffer_page gets bigger | |
305 | * than the struct page. | |
306 | */ | |
307 | extern int ring_buffer_page_too_big(void); | |
308 | ||
7a8e76a3 SR |
309 | /** |
310 | * ring_buffer_alloc - allocate a new ring_buffer | |
311 | * @size: the size in bytes that is needed. | |
312 | * @flags: attributes to set for the ring buffer. | |
313 | * | |
314 | * Currently the only flag that is available is the RB_FL_OVERWRITE | |
315 | * flag. This flag means that the buffer will overwrite old data | |
316 | * when the buffer wraps. If this flag is not set, the buffer will | |
317 | * drop data when the tail hits the head. | |
318 | */ | |
319 | struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags) | |
320 | { | |
321 | struct ring_buffer *buffer; | |
322 | int bsize; | |
323 | int cpu; | |
324 | ||
a7b13743 SR |
325 | /* Paranoid! Optimizes out when all is well */ |
326 | if (sizeof(struct buffer_page) > sizeof(struct page)) | |
327 | ring_buffer_page_too_big(); | |
328 | ||
329 | ||
7a8e76a3 SR |
330 | /* keep it in its own cache line */ |
331 | buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()), | |
332 | GFP_KERNEL); | |
333 | if (!buffer) | |
334 | return NULL; | |
335 | ||
336 | buffer->pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); | |
337 | buffer->flags = flags; | |
338 | ||
339 | /* need at least two pages */ | |
340 | if (buffer->pages == 1) | |
341 | buffer->pages++; | |
342 | ||
343 | buffer->cpumask = cpu_possible_map; | |
344 | buffer->cpus = nr_cpu_ids; | |
345 | ||
346 | bsize = sizeof(void *) * nr_cpu_ids; | |
347 | buffer->buffers = kzalloc(ALIGN(bsize, cache_line_size()), | |
348 | GFP_KERNEL); | |
349 | if (!buffer->buffers) | |
350 | goto fail_free_buffer; | |
351 | ||
352 | for_each_buffer_cpu(buffer, cpu) { | |
353 | buffer->buffers[cpu] = | |
354 | rb_allocate_cpu_buffer(buffer, cpu); | |
355 | if (!buffer->buffers[cpu]) | |
356 | goto fail_free_buffers; | |
357 | } | |
358 | ||
359 | mutex_init(&buffer->mutex); | |
360 | ||
361 | return buffer; | |
362 | ||
363 | fail_free_buffers: | |
364 | for_each_buffer_cpu(buffer, cpu) { | |
365 | if (buffer->buffers[cpu]) | |
366 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
367 | } | |
368 | kfree(buffer->buffers); | |
369 | ||
370 | fail_free_buffer: | |
371 | kfree(buffer); | |
372 | return NULL; | |
373 | } | |
374 | ||
375 | /** | |
376 | * ring_buffer_free - free a ring buffer. | |
377 | * @buffer: the buffer to free. | |
378 | */ | |
379 | void | |
380 | ring_buffer_free(struct ring_buffer *buffer) | |
381 | { | |
382 | int cpu; | |
383 | ||
384 | for_each_buffer_cpu(buffer, cpu) | |
385 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
386 | ||
387 | kfree(buffer); | |
388 | } | |
389 | ||
390 | static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer); | |
391 | ||
392 | static void | |
393 | rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages) | |
394 | { | |
395 | struct buffer_page *page; | |
396 | struct list_head *p; | |
397 | unsigned i; | |
398 | ||
399 | atomic_inc(&cpu_buffer->record_disabled); | |
400 | synchronize_sched(); | |
401 | ||
402 | for (i = 0; i < nr_pages; i++) { | |
403 | BUG_ON(list_empty(&cpu_buffer->pages)); | |
404 | p = cpu_buffer->pages.next; | |
405 | page = list_entry(p, struct buffer_page, list); | |
406 | list_del_init(&page->list); | |
ed56829c | 407 | free_buffer_page(page); |
7a8e76a3 SR |
408 | } |
409 | BUG_ON(list_empty(&cpu_buffer->pages)); | |
410 | ||
411 | rb_reset_cpu(cpu_buffer); | |
412 | ||
413 | rb_check_pages(cpu_buffer); | |
414 | ||
415 | atomic_dec(&cpu_buffer->record_disabled); | |
416 | ||
417 | } | |
418 | ||
419 | static void | |
420 | rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer, | |
421 | struct list_head *pages, unsigned nr_pages) | |
422 | { | |
423 | struct buffer_page *page; | |
424 | struct list_head *p; | |
425 | unsigned i; | |
426 | ||
427 | atomic_inc(&cpu_buffer->record_disabled); | |
428 | synchronize_sched(); | |
429 | ||
430 | for (i = 0; i < nr_pages; i++) { | |
431 | BUG_ON(list_empty(pages)); | |
432 | p = pages->next; | |
433 | page = list_entry(p, struct buffer_page, list); | |
434 | list_del_init(&page->list); | |
435 | list_add_tail(&page->list, &cpu_buffer->pages); | |
436 | } | |
437 | rb_reset_cpu(cpu_buffer); | |
438 | ||
439 | rb_check_pages(cpu_buffer); | |
440 | ||
441 | atomic_dec(&cpu_buffer->record_disabled); | |
442 | } | |
443 | ||
444 | /** | |
445 | * ring_buffer_resize - resize the ring buffer | |
446 | * @buffer: the buffer to resize. | |
447 | * @size: the new size. | |
448 | * | |
449 | * The tracer is responsible for making sure that the buffer is | |
450 | * not being used while changing the size. | |
451 | * Note: We may be able to change the above requirement by using | |
452 | * RCU synchronizations. | |
453 | * | |
454 | * Minimum size is 2 * BUF_PAGE_SIZE. | |
455 | * | |
456 | * Returns -1 on failure. | |
457 | */ | |
458 | int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size) | |
459 | { | |
460 | struct ring_buffer_per_cpu *cpu_buffer; | |
461 | unsigned nr_pages, rm_pages, new_pages; | |
462 | struct buffer_page *page, *tmp; | |
463 | unsigned long buffer_size; | |
464 | unsigned long addr; | |
465 | LIST_HEAD(pages); | |
466 | int i, cpu; | |
467 | ||
468 | size = DIV_ROUND_UP(size, BUF_PAGE_SIZE); | |
469 | size *= BUF_PAGE_SIZE; | |
470 | buffer_size = buffer->pages * BUF_PAGE_SIZE; | |
471 | ||
472 | /* we need a minimum of two pages */ | |
473 | if (size < BUF_PAGE_SIZE * 2) | |
474 | size = BUF_PAGE_SIZE * 2; | |
475 | ||
476 | if (size == buffer_size) | |
477 | return size; | |
478 | ||
479 | mutex_lock(&buffer->mutex); | |
480 | ||
481 | nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); | |
482 | ||
483 | if (size < buffer_size) { | |
484 | ||
485 | /* easy case, just free pages */ | |
486 | BUG_ON(nr_pages >= buffer->pages); | |
487 | ||
488 | rm_pages = buffer->pages - nr_pages; | |
489 | ||
490 | for_each_buffer_cpu(buffer, cpu) { | |
491 | cpu_buffer = buffer->buffers[cpu]; | |
492 | rb_remove_pages(cpu_buffer, rm_pages); | |
493 | } | |
494 | goto out; | |
495 | } | |
496 | ||
497 | /* | |
498 | * This is a bit more difficult. We only want to add pages | |
499 | * when we can allocate enough for all CPUs. We do this | |
500 | * by allocating all the pages and storing them on a local | |
501 | * link list. If we succeed in our allocation, then we | |
502 | * add these pages to the cpu_buffers. Otherwise we just free | |
503 | * them all and return -ENOMEM; | |
504 | */ | |
505 | BUG_ON(nr_pages <= buffer->pages); | |
506 | new_pages = nr_pages - buffer->pages; | |
507 | ||
508 | for_each_buffer_cpu(buffer, cpu) { | |
509 | for (i = 0; i < new_pages; i++) { | |
510 | addr = __get_free_page(GFP_KERNEL); | |
511 | if (!addr) | |
512 | goto free_pages; | |
513 | page = (struct buffer_page *)virt_to_page(addr); | |
514 | list_add(&page->list, &pages); | |
515 | } | |
516 | } | |
517 | ||
518 | for_each_buffer_cpu(buffer, cpu) { | |
519 | cpu_buffer = buffer->buffers[cpu]; | |
520 | rb_insert_pages(cpu_buffer, &pages, new_pages); | |
521 | } | |
522 | ||
523 | BUG_ON(!list_empty(&pages)); | |
524 | ||
525 | out: | |
526 | buffer->pages = nr_pages; | |
527 | mutex_unlock(&buffer->mutex); | |
528 | ||
529 | return size; | |
530 | ||
531 | free_pages: | |
532 | list_for_each_entry_safe(page, tmp, &pages, list) { | |
533 | list_del_init(&page->list); | |
ed56829c | 534 | free_buffer_page(page); |
7a8e76a3 SR |
535 | } |
536 | return -ENOMEM; | |
537 | } | |
538 | ||
539 | static inline int rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) | |
540 | { | |
541 | return cpu_buffer->head_page == cpu_buffer->tail_page && | |
542 | cpu_buffer->head == cpu_buffer->tail; | |
543 | } | |
544 | ||
545 | static inline int rb_null_event(struct ring_buffer_event *event) | |
546 | { | |
547 | return event->type == RINGBUF_TYPE_PADDING; | |
548 | } | |
549 | ||
550 | static inline void *rb_page_index(struct buffer_page *page, unsigned index) | |
551 | { | |
552 | void *addr = page_address(&page->page); | |
553 | ||
554 | return addr + index; | |
555 | } | |
556 | ||
557 | static inline struct ring_buffer_event * | |
558 | rb_head_event(struct ring_buffer_per_cpu *cpu_buffer) | |
559 | { | |
560 | return rb_page_index(cpu_buffer->head_page, | |
561 | cpu_buffer->head); | |
562 | } | |
563 | ||
564 | static inline struct ring_buffer_event * | |
565 | rb_iter_head_event(struct ring_buffer_iter *iter) | |
566 | { | |
567 | return rb_page_index(iter->head_page, | |
568 | iter->head); | |
569 | } | |
570 | ||
571 | /* | |
572 | * When the tail hits the head and the buffer is in overwrite mode, | |
573 | * the head jumps to the next page and all content on the previous | |
574 | * page is discarded. But before doing so, we update the overrun | |
575 | * variable of the buffer. | |
576 | */ | |
577 | static void rb_update_overflow(struct ring_buffer_per_cpu *cpu_buffer) | |
578 | { | |
579 | struct ring_buffer_event *event; | |
580 | unsigned long head; | |
581 | ||
582 | for (head = 0; head < rb_head_size(cpu_buffer); | |
583 | head += rb_event_length(event)) { | |
584 | ||
585 | event = rb_page_index(cpu_buffer->head_page, head); | |
586 | BUG_ON(rb_null_event(event)); | |
587 | /* Only count data entries */ | |
588 | if (event->type != RINGBUF_TYPE_DATA) | |
589 | continue; | |
590 | cpu_buffer->overrun++; | |
591 | cpu_buffer->entries--; | |
592 | } | |
593 | } | |
594 | ||
595 | static inline void rb_inc_page(struct ring_buffer_per_cpu *cpu_buffer, | |
596 | struct buffer_page **page) | |
597 | { | |
598 | struct list_head *p = (*page)->list.next; | |
599 | ||
600 | if (p == &cpu_buffer->pages) | |
601 | p = p->next; | |
602 | ||
603 | *page = list_entry(p, struct buffer_page, list); | |
604 | } | |
605 | ||
606 | static inline void | |
607 | rb_add_stamp(struct ring_buffer_per_cpu *cpu_buffer, u64 *ts) | |
608 | { | |
609 | cpu_buffer->tail_page->time_stamp = *ts; | |
610 | cpu_buffer->write_stamp = *ts; | |
611 | } | |
612 | ||
613 | static void rb_reset_read_page(struct ring_buffer_per_cpu *cpu_buffer) | |
614 | { | |
615 | cpu_buffer->read_stamp = cpu_buffer->head_page->time_stamp; | |
616 | cpu_buffer->head = 0; | |
617 | } | |
618 | ||
619 | static void | |
620 | rb_reset_iter_read_page(struct ring_buffer_iter *iter) | |
621 | { | |
622 | iter->read_stamp = iter->head_page->time_stamp; | |
623 | iter->head = 0; | |
624 | } | |
625 | ||
626 | /** | |
627 | * ring_buffer_update_event - update event type and data | |
628 | * @event: the even to update | |
629 | * @type: the type of event | |
630 | * @length: the size of the event field in the ring buffer | |
631 | * | |
632 | * Update the type and data fields of the event. The length | |
633 | * is the actual size that is written to the ring buffer, | |
634 | * and with this, we can determine what to place into the | |
635 | * data field. | |
636 | */ | |
637 | static inline void | |
638 | rb_update_event(struct ring_buffer_event *event, | |
639 | unsigned type, unsigned length) | |
640 | { | |
641 | event->type = type; | |
642 | ||
643 | switch (type) { | |
644 | ||
645 | case RINGBUF_TYPE_PADDING: | |
646 | break; | |
647 | ||
648 | case RINGBUF_TYPE_TIME_EXTEND: | |
649 | event->len = | |
650 | (RB_LEN_TIME_EXTEND + (RB_ALIGNMENT-1)) | |
651 | >> RB_ALIGNMENT_SHIFT; | |
652 | break; | |
653 | ||
654 | case RINGBUF_TYPE_TIME_STAMP: | |
655 | event->len = | |
656 | (RB_LEN_TIME_STAMP + (RB_ALIGNMENT-1)) | |
657 | >> RB_ALIGNMENT_SHIFT; | |
658 | break; | |
659 | ||
660 | case RINGBUF_TYPE_DATA: | |
661 | length -= RB_EVNT_HDR_SIZE; | |
662 | if (length > RB_MAX_SMALL_DATA) { | |
663 | event->len = 0; | |
664 | event->array[0] = length; | |
665 | } else | |
666 | event->len = | |
667 | (length + (RB_ALIGNMENT-1)) | |
668 | >> RB_ALIGNMENT_SHIFT; | |
669 | break; | |
670 | default: | |
671 | BUG(); | |
672 | } | |
673 | } | |
674 | ||
675 | static inline unsigned rb_calculate_event_length(unsigned length) | |
676 | { | |
677 | struct ring_buffer_event event; /* Used only for sizeof array */ | |
678 | ||
679 | /* zero length can cause confusions */ | |
680 | if (!length) | |
681 | length = 1; | |
682 | ||
683 | if (length > RB_MAX_SMALL_DATA) | |
684 | length += sizeof(event.array[0]); | |
685 | ||
686 | length += RB_EVNT_HDR_SIZE; | |
687 | length = ALIGN(length, RB_ALIGNMENT); | |
688 | ||
689 | return length; | |
690 | } | |
691 | ||
692 | static struct ring_buffer_event * | |
693 | __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, | |
694 | unsigned type, unsigned long length, u64 *ts) | |
695 | { | |
696 | struct buffer_page *head_page, *tail_page; | |
697 | unsigned long tail; | |
698 | struct ring_buffer *buffer = cpu_buffer->buffer; | |
699 | struct ring_buffer_event *event; | |
700 | ||
701 | tail_page = cpu_buffer->tail_page; | |
702 | head_page = cpu_buffer->head_page; | |
703 | tail = cpu_buffer->tail; | |
704 | ||
705 | if (tail + length > BUF_PAGE_SIZE) { | |
706 | struct buffer_page *next_page = tail_page; | |
707 | ||
708 | rb_inc_page(cpu_buffer, &next_page); | |
709 | ||
710 | if (next_page == head_page) { | |
711 | if (!(buffer->flags & RB_FL_OVERWRITE)) | |
712 | return NULL; | |
713 | ||
714 | /* count overflows */ | |
715 | rb_update_overflow(cpu_buffer); | |
716 | ||
717 | rb_inc_page(cpu_buffer, &head_page); | |
718 | cpu_buffer->head_page = head_page; | |
719 | rb_reset_read_page(cpu_buffer); | |
720 | } | |
721 | ||
722 | if (tail != BUF_PAGE_SIZE) { | |
723 | event = rb_page_index(tail_page, tail); | |
724 | /* page padding */ | |
725 | event->type = RINGBUF_TYPE_PADDING; | |
726 | } | |
727 | ||
728 | tail_page->size = tail; | |
729 | tail_page = next_page; | |
730 | tail_page->size = 0; | |
731 | tail = 0; | |
732 | cpu_buffer->tail_page = tail_page; | |
733 | cpu_buffer->tail = tail; | |
734 | rb_add_stamp(cpu_buffer, ts); | |
735 | } | |
736 | ||
737 | BUG_ON(tail + length > BUF_PAGE_SIZE); | |
738 | ||
739 | event = rb_page_index(tail_page, tail); | |
740 | rb_update_event(event, type, length); | |
741 | ||
742 | return event; | |
743 | } | |
744 | ||
745 | static int | |
746 | rb_add_time_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
747 | u64 *ts, u64 *delta) | |
748 | { | |
749 | struct ring_buffer_event *event; | |
750 | static int once; | |
751 | ||
752 | if (unlikely(*delta > (1ULL << 59) && !once++)) { | |
753 | printk(KERN_WARNING "Delta way too big! %llu" | |
754 | " ts=%llu write stamp = %llu\n", | |
755 | *delta, *ts, cpu_buffer->write_stamp); | |
756 | WARN_ON(1); | |
757 | } | |
758 | ||
759 | /* | |
760 | * The delta is too big, we to add a | |
761 | * new timestamp. | |
762 | */ | |
763 | event = __rb_reserve_next(cpu_buffer, | |
764 | RINGBUF_TYPE_TIME_EXTEND, | |
765 | RB_LEN_TIME_EXTEND, | |
766 | ts); | |
767 | if (!event) | |
768 | return -1; | |
769 | ||
770 | /* check to see if we went to the next page */ | |
771 | if (cpu_buffer->tail) { | |
772 | /* Still on same page, update timestamp */ | |
773 | event->time_delta = *delta & TS_MASK; | |
774 | event->array[0] = *delta >> TS_SHIFT; | |
775 | /* commit the time event */ | |
776 | cpu_buffer->tail += | |
777 | rb_event_length(event); | |
778 | cpu_buffer->write_stamp = *ts; | |
779 | *delta = 0; | |
780 | } | |
781 | ||
782 | return 0; | |
783 | } | |
784 | ||
785 | static struct ring_buffer_event * | |
786 | rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer, | |
787 | unsigned type, unsigned long length) | |
788 | { | |
789 | struct ring_buffer_event *event; | |
790 | u64 ts, delta; | |
791 | ||
792 | ts = ring_buffer_time_stamp(cpu_buffer->cpu); | |
793 | ||
794 | if (cpu_buffer->tail) { | |
795 | delta = ts - cpu_buffer->write_stamp; | |
796 | ||
797 | if (test_time_stamp(delta)) { | |
798 | int ret; | |
799 | ||
800 | ret = rb_add_time_stamp(cpu_buffer, &ts, &delta); | |
801 | if (ret < 0) | |
802 | return NULL; | |
803 | } | |
804 | } else { | |
805 | rb_add_stamp(cpu_buffer, &ts); | |
806 | delta = 0; | |
807 | } | |
808 | ||
809 | event = __rb_reserve_next(cpu_buffer, type, length, &ts); | |
810 | if (!event) | |
811 | return NULL; | |
812 | ||
813 | /* If the reserve went to the next page, our delta is zero */ | |
814 | if (!cpu_buffer->tail) | |
815 | delta = 0; | |
816 | ||
817 | event->time_delta = delta; | |
818 | ||
819 | return event; | |
820 | } | |
821 | ||
822 | /** | |
823 | * ring_buffer_lock_reserve - reserve a part of the buffer | |
824 | * @buffer: the ring buffer to reserve from | |
825 | * @length: the length of the data to reserve (excluding event header) | |
826 | * @flags: a pointer to save the interrupt flags | |
827 | * | |
828 | * Returns a reseverd event on the ring buffer to copy directly to. | |
829 | * The user of this interface will need to get the body to write into | |
830 | * and can use the ring_buffer_event_data() interface. | |
831 | * | |
832 | * The length is the length of the data needed, not the event length | |
833 | * which also includes the event header. | |
834 | * | |
835 | * Must be paired with ring_buffer_unlock_commit, unless NULL is returned. | |
836 | * If NULL is returned, then nothing has been allocated or locked. | |
837 | */ | |
838 | struct ring_buffer_event * | |
839 | ring_buffer_lock_reserve(struct ring_buffer *buffer, | |
840 | unsigned long length, | |
841 | unsigned long *flags) | |
842 | { | |
843 | struct ring_buffer_per_cpu *cpu_buffer; | |
844 | struct ring_buffer_event *event; | |
845 | int cpu; | |
846 | ||
847 | if (atomic_read(&buffer->record_disabled)) | |
848 | return NULL; | |
849 | ||
70255b5e | 850 | local_irq_save(*flags); |
7a8e76a3 SR |
851 | cpu = raw_smp_processor_id(); |
852 | ||
853 | if (!cpu_isset(cpu, buffer->cpumask)) | |
854 | goto out_irq; | |
855 | ||
856 | cpu_buffer = buffer->buffers[cpu]; | |
857 | spin_lock(&cpu_buffer->lock); | |
858 | ||
859 | if (atomic_read(&cpu_buffer->record_disabled)) | |
860 | goto no_record; | |
861 | ||
862 | length = rb_calculate_event_length(length); | |
863 | if (length > BUF_PAGE_SIZE) | |
864 | return NULL; | |
865 | ||
866 | event = rb_reserve_next_event(cpu_buffer, RINGBUF_TYPE_DATA, length); | |
867 | if (!event) | |
868 | goto no_record; | |
869 | ||
870 | return event; | |
871 | ||
872 | no_record: | |
873 | spin_unlock(&cpu_buffer->lock); | |
874 | out_irq: | |
875 | local_irq_restore(*flags); | |
876 | return NULL; | |
877 | } | |
878 | ||
879 | static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, | |
880 | struct ring_buffer_event *event) | |
881 | { | |
882 | cpu_buffer->tail += rb_event_length(event); | |
883 | cpu_buffer->tail_page->size = cpu_buffer->tail; | |
884 | cpu_buffer->write_stamp += event->time_delta; | |
885 | cpu_buffer->entries++; | |
886 | } | |
887 | ||
888 | /** | |
889 | * ring_buffer_unlock_commit - commit a reserved | |
890 | * @buffer: The buffer to commit to | |
891 | * @event: The event pointer to commit. | |
892 | * @flags: the interrupt flags received from ring_buffer_lock_reserve. | |
893 | * | |
894 | * This commits the data to the ring buffer, and releases any locks held. | |
895 | * | |
896 | * Must be paired with ring_buffer_lock_reserve. | |
897 | */ | |
898 | int ring_buffer_unlock_commit(struct ring_buffer *buffer, | |
899 | struct ring_buffer_event *event, | |
900 | unsigned long flags) | |
901 | { | |
902 | struct ring_buffer_per_cpu *cpu_buffer; | |
903 | int cpu = raw_smp_processor_id(); | |
904 | ||
905 | cpu_buffer = buffer->buffers[cpu]; | |
906 | ||
907 | assert_spin_locked(&cpu_buffer->lock); | |
908 | ||
909 | rb_commit(cpu_buffer, event); | |
910 | ||
911 | spin_unlock(&cpu_buffer->lock); | |
70255b5e | 912 | local_irq_restore(flags); |
7a8e76a3 SR |
913 | |
914 | return 0; | |
915 | } | |
916 | ||
917 | /** | |
918 | * ring_buffer_write - write data to the buffer without reserving | |
919 | * @buffer: The ring buffer to write to. | |
920 | * @length: The length of the data being written (excluding the event header) | |
921 | * @data: The data to write to the buffer. | |
922 | * | |
923 | * This is like ring_buffer_lock_reserve and ring_buffer_unlock_commit as | |
924 | * one function. If you already have the data to write to the buffer, it | |
925 | * may be easier to simply call this function. | |
926 | * | |
927 | * Note, like ring_buffer_lock_reserve, the length is the length of the data | |
928 | * and not the length of the event which would hold the header. | |
929 | */ | |
930 | int ring_buffer_write(struct ring_buffer *buffer, | |
931 | unsigned long length, | |
932 | void *data) | |
933 | { | |
934 | struct ring_buffer_per_cpu *cpu_buffer; | |
935 | struct ring_buffer_event *event; | |
936 | unsigned long event_length, flags; | |
937 | void *body; | |
938 | int ret = -EBUSY; | |
939 | int cpu; | |
940 | ||
941 | if (atomic_read(&buffer->record_disabled)) | |
942 | return -EBUSY; | |
943 | ||
944 | local_irq_save(flags); | |
945 | cpu = raw_smp_processor_id(); | |
946 | ||
947 | if (!cpu_isset(cpu, buffer->cpumask)) | |
948 | goto out_irq; | |
949 | ||
950 | cpu_buffer = buffer->buffers[cpu]; | |
951 | spin_lock(&cpu_buffer->lock); | |
952 | ||
953 | if (atomic_read(&cpu_buffer->record_disabled)) | |
954 | goto out; | |
955 | ||
956 | event_length = rb_calculate_event_length(length); | |
957 | event = rb_reserve_next_event(cpu_buffer, | |
958 | RINGBUF_TYPE_DATA, event_length); | |
959 | if (!event) | |
960 | goto out; | |
961 | ||
962 | body = rb_event_data(event); | |
963 | ||
964 | memcpy(body, data, length); | |
965 | ||
966 | rb_commit(cpu_buffer, event); | |
967 | ||
968 | ret = 0; | |
969 | out: | |
970 | spin_unlock(&cpu_buffer->lock); | |
971 | out_irq: | |
972 | local_irq_restore(flags); | |
973 | ||
974 | return ret; | |
975 | } | |
976 | ||
977 | /** | |
978 | * ring_buffer_lock - lock the ring buffer | |
979 | * @buffer: The ring buffer to lock | |
980 | * @flags: The place to store the interrupt flags | |
981 | * | |
982 | * This locks all the per CPU buffers. | |
983 | * | |
984 | * Must be unlocked by ring_buffer_unlock. | |
985 | */ | |
986 | void ring_buffer_lock(struct ring_buffer *buffer, unsigned long *flags) | |
987 | { | |
988 | struct ring_buffer_per_cpu *cpu_buffer; | |
989 | int cpu; | |
990 | ||
991 | local_irq_save(*flags); | |
992 | ||
993 | for_each_buffer_cpu(buffer, cpu) { | |
994 | cpu_buffer = buffer->buffers[cpu]; | |
995 | spin_lock(&cpu_buffer->lock); | |
996 | } | |
997 | } | |
998 | ||
999 | /** | |
1000 | * ring_buffer_unlock - unlock a locked buffer | |
1001 | * @buffer: The locked buffer to unlock | |
1002 | * @flags: The interrupt flags received by ring_buffer_lock | |
1003 | */ | |
1004 | void ring_buffer_unlock(struct ring_buffer *buffer, unsigned long flags) | |
1005 | { | |
1006 | struct ring_buffer_per_cpu *cpu_buffer; | |
1007 | int cpu; | |
1008 | ||
1009 | for (cpu = buffer->cpus - 1; cpu >= 0; cpu--) { | |
1010 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1011 | continue; | |
1012 | cpu_buffer = buffer->buffers[cpu]; | |
1013 | spin_unlock(&cpu_buffer->lock); | |
1014 | } | |
1015 | ||
1016 | local_irq_restore(flags); | |
1017 | } | |
1018 | ||
1019 | /** | |
1020 | * ring_buffer_record_disable - stop all writes into the buffer | |
1021 | * @buffer: The ring buffer to stop writes to. | |
1022 | * | |
1023 | * This prevents all writes to the buffer. Any attempt to write | |
1024 | * to the buffer after this will fail and return NULL. | |
1025 | * | |
1026 | * The caller should call synchronize_sched() after this. | |
1027 | */ | |
1028 | void ring_buffer_record_disable(struct ring_buffer *buffer) | |
1029 | { | |
1030 | atomic_inc(&buffer->record_disabled); | |
1031 | } | |
1032 | ||
1033 | /** | |
1034 | * ring_buffer_record_enable - enable writes to the buffer | |
1035 | * @buffer: The ring buffer to enable writes | |
1036 | * | |
1037 | * Note, multiple disables will need the same number of enables | |
1038 | * to truely enable the writing (much like preempt_disable). | |
1039 | */ | |
1040 | void ring_buffer_record_enable(struct ring_buffer *buffer) | |
1041 | { | |
1042 | atomic_dec(&buffer->record_disabled); | |
1043 | } | |
1044 | ||
1045 | /** | |
1046 | * ring_buffer_record_disable_cpu - stop all writes into the cpu_buffer | |
1047 | * @buffer: The ring buffer to stop writes to. | |
1048 | * @cpu: The CPU buffer to stop | |
1049 | * | |
1050 | * This prevents all writes to the buffer. Any attempt to write | |
1051 | * to the buffer after this will fail and return NULL. | |
1052 | * | |
1053 | * The caller should call synchronize_sched() after this. | |
1054 | */ | |
1055 | void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu) | |
1056 | { | |
1057 | struct ring_buffer_per_cpu *cpu_buffer; | |
1058 | ||
1059 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1060 | return; | |
1061 | ||
1062 | cpu_buffer = buffer->buffers[cpu]; | |
1063 | atomic_inc(&cpu_buffer->record_disabled); | |
1064 | } | |
1065 | ||
1066 | /** | |
1067 | * ring_buffer_record_enable_cpu - enable writes to the buffer | |
1068 | * @buffer: The ring buffer to enable writes | |
1069 | * @cpu: The CPU to enable. | |
1070 | * | |
1071 | * Note, multiple disables will need the same number of enables | |
1072 | * to truely enable the writing (much like preempt_disable). | |
1073 | */ | |
1074 | void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu) | |
1075 | { | |
1076 | struct ring_buffer_per_cpu *cpu_buffer; | |
1077 | ||
1078 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1079 | return; | |
1080 | ||
1081 | cpu_buffer = buffer->buffers[cpu]; | |
1082 | atomic_dec(&cpu_buffer->record_disabled); | |
1083 | } | |
1084 | ||
1085 | /** | |
1086 | * ring_buffer_entries_cpu - get the number of entries in a cpu buffer | |
1087 | * @buffer: The ring buffer | |
1088 | * @cpu: The per CPU buffer to get the entries from. | |
1089 | */ | |
1090 | unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu) | |
1091 | { | |
1092 | struct ring_buffer_per_cpu *cpu_buffer; | |
1093 | ||
1094 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1095 | return 0; | |
1096 | ||
1097 | cpu_buffer = buffer->buffers[cpu]; | |
1098 | return cpu_buffer->entries; | |
1099 | } | |
1100 | ||
1101 | /** | |
1102 | * ring_buffer_overrun_cpu - get the number of overruns in a cpu_buffer | |
1103 | * @buffer: The ring buffer | |
1104 | * @cpu: The per CPU buffer to get the number of overruns from | |
1105 | */ | |
1106 | unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu) | |
1107 | { | |
1108 | struct ring_buffer_per_cpu *cpu_buffer; | |
1109 | ||
1110 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1111 | return 0; | |
1112 | ||
1113 | cpu_buffer = buffer->buffers[cpu]; | |
1114 | return cpu_buffer->overrun; | |
1115 | } | |
1116 | ||
1117 | /** | |
1118 | * ring_buffer_entries - get the number of entries in a buffer | |
1119 | * @buffer: The ring buffer | |
1120 | * | |
1121 | * Returns the total number of entries in the ring buffer | |
1122 | * (all CPU entries) | |
1123 | */ | |
1124 | unsigned long ring_buffer_entries(struct ring_buffer *buffer) | |
1125 | { | |
1126 | struct ring_buffer_per_cpu *cpu_buffer; | |
1127 | unsigned long entries = 0; | |
1128 | int cpu; | |
1129 | ||
1130 | /* if you care about this being correct, lock the buffer */ | |
1131 | for_each_buffer_cpu(buffer, cpu) { | |
1132 | cpu_buffer = buffer->buffers[cpu]; | |
1133 | entries += cpu_buffer->entries; | |
1134 | } | |
1135 | ||
1136 | return entries; | |
1137 | } | |
1138 | ||
1139 | /** | |
1140 | * ring_buffer_overrun_cpu - get the number of overruns in buffer | |
1141 | * @buffer: The ring buffer | |
1142 | * | |
1143 | * Returns the total number of overruns in the ring buffer | |
1144 | * (all CPU entries) | |
1145 | */ | |
1146 | unsigned long ring_buffer_overruns(struct ring_buffer *buffer) | |
1147 | { | |
1148 | struct ring_buffer_per_cpu *cpu_buffer; | |
1149 | unsigned long overruns = 0; | |
1150 | int cpu; | |
1151 | ||
1152 | /* if you care about this being correct, lock the buffer */ | |
1153 | for_each_buffer_cpu(buffer, cpu) { | |
1154 | cpu_buffer = buffer->buffers[cpu]; | |
1155 | overruns += cpu_buffer->overrun; | |
1156 | } | |
1157 | ||
1158 | return overruns; | |
1159 | } | |
1160 | ||
1161 | /** | |
1162 | * ring_buffer_iter_reset - reset an iterator | |
1163 | * @iter: The iterator to reset | |
1164 | * | |
1165 | * Resets the iterator, so that it will start from the beginning | |
1166 | * again. | |
1167 | */ | |
1168 | void ring_buffer_iter_reset(struct ring_buffer_iter *iter) | |
1169 | { | |
1170 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
1171 | ||
1172 | iter->head_page = cpu_buffer->head_page; | |
1173 | iter->head = cpu_buffer->head; | |
1174 | rb_reset_iter_read_page(iter); | |
1175 | } | |
1176 | ||
1177 | /** | |
1178 | * ring_buffer_iter_empty - check if an iterator has no more to read | |
1179 | * @iter: The iterator to check | |
1180 | */ | |
1181 | int ring_buffer_iter_empty(struct ring_buffer_iter *iter) | |
1182 | { | |
1183 | struct ring_buffer_per_cpu *cpu_buffer; | |
1184 | ||
1185 | cpu_buffer = iter->cpu_buffer; | |
1186 | ||
1187 | return iter->head_page == cpu_buffer->tail_page && | |
1188 | iter->head == cpu_buffer->tail; | |
1189 | } | |
1190 | ||
1191 | static void | |
1192 | rb_update_read_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
1193 | struct ring_buffer_event *event) | |
1194 | { | |
1195 | u64 delta; | |
1196 | ||
1197 | switch (event->type) { | |
1198 | case RINGBUF_TYPE_PADDING: | |
1199 | return; | |
1200 | ||
1201 | case RINGBUF_TYPE_TIME_EXTEND: | |
1202 | delta = event->array[0]; | |
1203 | delta <<= TS_SHIFT; | |
1204 | delta += event->time_delta; | |
1205 | cpu_buffer->read_stamp += delta; | |
1206 | return; | |
1207 | ||
1208 | case RINGBUF_TYPE_TIME_STAMP: | |
1209 | /* FIXME: not implemented */ | |
1210 | return; | |
1211 | ||
1212 | case RINGBUF_TYPE_DATA: | |
1213 | cpu_buffer->read_stamp += event->time_delta; | |
1214 | return; | |
1215 | ||
1216 | default: | |
1217 | BUG(); | |
1218 | } | |
1219 | return; | |
1220 | } | |
1221 | ||
1222 | static void | |
1223 | rb_update_iter_read_stamp(struct ring_buffer_iter *iter, | |
1224 | struct ring_buffer_event *event) | |
1225 | { | |
1226 | u64 delta; | |
1227 | ||
1228 | switch (event->type) { | |
1229 | case RINGBUF_TYPE_PADDING: | |
1230 | return; | |
1231 | ||
1232 | case RINGBUF_TYPE_TIME_EXTEND: | |
1233 | delta = event->array[0]; | |
1234 | delta <<= TS_SHIFT; | |
1235 | delta += event->time_delta; | |
1236 | iter->read_stamp += delta; | |
1237 | return; | |
1238 | ||
1239 | case RINGBUF_TYPE_TIME_STAMP: | |
1240 | /* FIXME: not implemented */ | |
1241 | return; | |
1242 | ||
1243 | case RINGBUF_TYPE_DATA: | |
1244 | iter->read_stamp += event->time_delta; | |
1245 | return; | |
1246 | ||
1247 | default: | |
1248 | BUG(); | |
1249 | } | |
1250 | return; | |
1251 | } | |
1252 | ||
1253 | static void rb_advance_head(struct ring_buffer_per_cpu *cpu_buffer) | |
1254 | { | |
1255 | struct ring_buffer_event *event; | |
1256 | unsigned length; | |
1257 | ||
1258 | /* | |
1259 | * Check if we are at the end of the buffer. | |
1260 | */ | |
1261 | if (cpu_buffer->head >= cpu_buffer->head_page->size) { | |
1262 | BUG_ON(cpu_buffer->head_page == cpu_buffer->tail_page); | |
1263 | rb_inc_page(cpu_buffer, &cpu_buffer->head_page); | |
1264 | rb_reset_read_page(cpu_buffer); | |
1265 | return; | |
1266 | } | |
1267 | ||
1268 | event = rb_head_event(cpu_buffer); | |
1269 | ||
1270 | if (event->type == RINGBUF_TYPE_DATA) | |
1271 | cpu_buffer->entries--; | |
1272 | ||
1273 | length = rb_event_length(event); | |
1274 | ||
1275 | /* | |
1276 | * This should not be called to advance the header if we are | |
1277 | * at the tail of the buffer. | |
1278 | */ | |
1279 | BUG_ON((cpu_buffer->head_page == cpu_buffer->tail_page) && | |
1280 | (cpu_buffer->head + length > cpu_buffer->tail)); | |
1281 | ||
1282 | rb_update_read_stamp(cpu_buffer, event); | |
1283 | ||
1284 | cpu_buffer->head += length; | |
1285 | ||
1286 | /* check for end of page */ | |
1287 | if ((cpu_buffer->head >= cpu_buffer->head_page->size) && | |
1288 | (cpu_buffer->head_page != cpu_buffer->tail_page)) | |
1289 | rb_advance_head(cpu_buffer); | |
1290 | } | |
1291 | ||
1292 | static void rb_advance_iter(struct ring_buffer_iter *iter) | |
1293 | { | |
1294 | struct ring_buffer *buffer; | |
1295 | struct ring_buffer_per_cpu *cpu_buffer; | |
1296 | struct ring_buffer_event *event; | |
1297 | unsigned length; | |
1298 | ||
1299 | cpu_buffer = iter->cpu_buffer; | |
1300 | buffer = cpu_buffer->buffer; | |
1301 | ||
1302 | /* | |
1303 | * Check if we are at the end of the buffer. | |
1304 | */ | |
1305 | if (iter->head >= iter->head_page->size) { | |
1306 | BUG_ON(iter->head_page == cpu_buffer->tail_page); | |
1307 | rb_inc_page(cpu_buffer, &iter->head_page); | |
1308 | rb_reset_iter_read_page(iter); | |
1309 | return; | |
1310 | } | |
1311 | ||
1312 | event = rb_iter_head_event(iter); | |
1313 | ||
1314 | length = rb_event_length(event); | |
1315 | ||
1316 | /* | |
1317 | * This should not be called to advance the header if we are | |
1318 | * at the tail of the buffer. | |
1319 | */ | |
1320 | BUG_ON((iter->head_page == cpu_buffer->tail_page) && | |
1321 | (iter->head + length > cpu_buffer->tail)); | |
1322 | ||
1323 | rb_update_iter_read_stamp(iter, event); | |
1324 | ||
1325 | iter->head += length; | |
1326 | ||
1327 | /* check for end of page padding */ | |
1328 | if ((iter->head >= iter->head_page->size) && | |
1329 | (iter->head_page != cpu_buffer->tail_page)) | |
1330 | rb_advance_iter(iter); | |
1331 | } | |
1332 | ||
1333 | /** | |
1334 | * ring_buffer_peek - peek at the next event to be read | |
1335 | * @buffer: The ring buffer to read | |
1336 | * @cpu: The cpu to peak at | |
1337 | * @ts: The timestamp counter of this event. | |
1338 | * | |
1339 | * This will return the event that will be read next, but does | |
1340 | * not consume the data. | |
1341 | */ | |
1342 | struct ring_buffer_event * | |
1343 | ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) | |
1344 | { | |
1345 | struct ring_buffer_per_cpu *cpu_buffer; | |
1346 | struct ring_buffer_event *event; | |
1347 | ||
1348 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1349 | return NULL; | |
1350 | ||
1351 | cpu_buffer = buffer->buffers[cpu]; | |
1352 | ||
1353 | again: | |
1354 | if (rb_per_cpu_empty(cpu_buffer)) | |
1355 | return NULL; | |
1356 | ||
1357 | event = rb_head_event(cpu_buffer); | |
1358 | ||
1359 | switch (event->type) { | |
1360 | case RINGBUF_TYPE_PADDING: | |
1361 | rb_inc_page(cpu_buffer, &cpu_buffer->head_page); | |
1362 | rb_reset_read_page(cpu_buffer); | |
1363 | goto again; | |
1364 | ||
1365 | case RINGBUF_TYPE_TIME_EXTEND: | |
1366 | /* Internal data, OK to advance */ | |
1367 | rb_advance_head(cpu_buffer); | |
1368 | goto again; | |
1369 | ||
1370 | case RINGBUF_TYPE_TIME_STAMP: | |
1371 | /* FIXME: not implemented */ | |
1372 | rb_advance_head(cpu_buffer); | |
1373 | goto again; | |
1374 | ||
1375 | case RINGBUF_TYPE_DATA: | |
1376 | if (ts) { | |
1377 | *ts = cpu_buffer->read_stamp + event->time_delta; | |
1378 | ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts); | |
1379 | } | |
1380 | return event; | |
1381 | ||
1382 | default: | |
1383 | BUG(); | |
1384 | } | |
1385 | ||
1386 | return NULL; | |
1387 | } | |
1388 | ||
1389 | /** | |
1390 | * ring_buffer_iter_peek - peek at the next event to be read | |
1391 | * @iter: The ring buffer iterator | |
1392 | * @ts: The timestamp counter of this event. | |
1393 | * | |
1394 | * This will return the event that will be read next, but does | |
1395 | * not increment the iterator. | |
1396 | */ | |
1397 | struct ring_buffer_event * | |
1398 | ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) | |
1399 | { | |
1400 | struct ring_buffer *buffer; | |
1401 | struct ring_buffer_per_cpu *cpu_buffer; | |
1402 | struct ring_buffer_event *event; | |
1403 | ||
1404 | if (ring_buffer_iter_empty(iter)) | |
1405 | return NULL; | |
1406 | ||
1407 | cpu_buffer = iter->cpu_buffer; | |
1408 | buffer = cpu_buffer->buffer; | |
1409 | ||
1410 | again: | |
1411 | if (rb_per_cpu_empty(cpu_buffer)) | |
1412 | return NULL; | |
1413 | ||
1414 | event = rb_iter_head_event(iter); | |
1415 | ||
1416 | switch (event->type) { | |
1417 | case RINGBUF_TYPE_PADDING: | |
1418 | rb_inc_page(cpu_buffer, &iter->head_page); | |
1419 | rb_reset_iter_read_page(iter); | |
1420 | goto again; | |
1421 | ||
1422 | case RINGBUF_TYPE_TIME_EXTEND: | |
1423 | /* Internal data, OK to advance */ | |
1424 | rb_advance_iter(iter); | |
1425 | goto again; | |
1426 | ||
1427 | case RINGBUF_TYPE_TIME_STAMP: | |
1428 | /* FIXME: not implemented */ | |
1429 | rb_advance_iter(iter); | |
1430 | goto again; | |
1431 | ||
1432 | case RINGBUF_TYPE_DATA: | |
1433 | if (ts) { | |
1434 | *ts = iter->read_stamp + event->time_delta; | |
1435 | ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts); | |
1436 | } | |
1437 | return event; | |
1438 | ||
1439 | default: | |
1440 | BUG(); | |
1441 | } | |
1442 | ||
1443 | return NULL; | |
1444 | } | |
1445 | ||
1446 | /** | |
1447 | * ring_buffer_consume - return an event and consume it | |
1448 | * @buffer: The ring buffer to get the next event from | |
1449 | * | |
1450 | * Returns the next event in the ring buffer, and that event is consumed. | |
1451 | * Meaning, that sequential reads will keep returning a different event, | |
1452 | * and eventually empty the ring buffer if the producer is slower. | |
1453 | */ | |
1454 | struct ring_buffer_event * | |
1455 | ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts) | |
1456 | { | |
1457 | struct ring_buffer_per_cpu *cpu_buffer; | |
1458 | struct ring_buffer_event *event; | |
1459 | ||
1460 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1461 | return NULL; | |
1462 | ||
1463 | event = ring_buffer_peek(buffer, cpu, ts); | |
1464 | if (!event) | |
1465 | return NULL; | |
1466 | ||
1467 | cpu_buffer = buffer->buffers[cpu]; | |
1468 | rb_advance_head(cpu_buffer); | |
1469 | ||
1470 | return event; | |
1471 | } | |
1472 | ||
1473 | /** | |
1474 | * ring_buffer_read_start - start a non consuming read of the buffer | |
1475 | * @buffer: The ring buffer to read from | |
1476 | * @cpu: The cpu buffer to iterate over | |
1477 | * | |
1478 | * This starts up an iteration through the buffer. It also disables | |
1479 | * the recording to the buffer until the reading is finished. | |
1480 | * This prevents the reading from being corrupted. This is not | |
1481 | * a consuming read, so a producer is not expected. | |
1482 | * | |
1483 | * Must be paired with ring_buffer_finish. | |
1484 | */ | |
1485 | struct ring_buffer_iter * | |
1486 | ring_buffer_read_start(struct ring_buffer *buffer, int cpu) | |
1487 | { | |
1488 | struct ring_buffer_per_cpu *cpu_buffer; | |
1489 | struct ring_buffer_iter *iter; | |
1490 | ||
1491 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1492 | return NULL; | |
1493 | ||
1494 | iter = kmalloc(sizeof(*iter), GFP_KERNEL); | |
1495 | if (!iter) | |
1496 | return NULL; | |
1497 | ||
1498 | cpu_buffer = buffer->buffers[cpu]; | |
1499 | ||
1500 | iter->cpu_buffer = cpu_buffer; | |
1501 | ||
1502 | atomic_inc(&cpu_buffer->record_disabled); | |
1503 | synchronize_sched(); | |
1504 | ||
1505 | spin_lock(&cpu_buffer->lock); | |
1506 | iter->head = cpu_buffer->head; | |
1507 | iter->head_page = cpu_buffer->head_page; | |
1508 | rb_reset_iter_read_page(iter); | |
1509 | spin_unlock(&cpu_buffer->lock); | |
1510 | ||
1511 | return iter; | |
1512 | } | |
1513 | ||
1514 | /** | |
1515 | * ring_buffer_finish - finish reading the iterator of the buffer | |
1516 | * @iter: The iterator retrieved by ring_buffer_start | |
1517 | * | |
1518 | * This re-enables the recording to the buffer, and frees the | |
1519 | * iterator. | |
1520 | */ | |
1521 | void | |
1522 | ring_buffer_read_finish(struct ring_buffer_iter *iter) | |
1523 | { | |
1524 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
1525 | ||
1526 | atomic_dec(&cpu_buffer->record_disabled); | |
1527 | kfree(iter); | |
1528 | } | |
1529 | ||
1530 | /** | |
1531 | * ring_buffer_read - read the next item in the ring buffer by the iterator | |
1532 | * @iter: The ring buffer iterator | |
1533 | * @ts: The time stamp of the event read. | |
1534 | * | |
1535 | * This reads the next event in the ring buffer and increments the iterator. | |
1536 | */ | |
1537 | struct ring_buffer_event * | |
1538 | ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) | |
1539 | { | |
1540 | struct ring_buffer_event *event; | |
1541 | ||
1542 | event = ring_buffer_iter_peek(iter, ts); | |
1543 | if (!event) | |
1544 | return NULL; | |
1545 | ||
1546 | rb_advance_iter(iter); | |
1547 | ||
1548 | return event; | |
1549 | } | |
1550 | ||
1551 | /** | |
1552 | * ring_buffer_size - return the size of the ring buffer (in bytes) | |
1553 | * @buffer: The ring buffer. | |
1554 | */ | |
1555 | unsigned long ring_buffer_size(struct ring_buffer *buffer) | |
1556 | { | |
1557 | return BUF_PAGE_SIZE * buffer->pages; | |
1558 | } | |
1559 | ||
1560 | static void | |
1561 | rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) | |
1562 | { | |
1563 | cpu_buffer->head_page | |
1564 | = list_entry(cpu_buffer->pages.next, struct buffer_page, list); | |
1565 | cpu_buffer->tail_page | |
1566 | = list_entry(cpu_buffer->pages.next, struct buffer_page, list); | |
1567 | ||
1568 | cpu_buffer->head = cpu_buffer->tail = 0; | |
1569 | cpu_buffer->overrun = 0; | |
1570 | cpu_buffer->entries = 0; | |
1571 | } | |
1572 | ||
1573 | /** | |
1574 | * ring_buffer_reset_cpu - reset a ring buffer per CPU buffer | |
1575 | * @buffer: The ring buffer to reset a per cpu buffer of | |
1576 | * @cpu: The CPU buffer to be reset | |
1577 | */ | |
1578 | void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) | |
1579 | { | |
1580 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
1581 | unsigned long flags; | |
1582 | ||
1583 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1584 | return; | |
1585 | ||
70255b5e | 1586 | local_irq_save(flags); |
7a8e76a3 SR |
1587 | spin_lock(&cpu_buffer->lock); |
1588 | ||
1589 | rb_reset_cpu(cpu_buffer); | |
1590 | ||
1591 | spin_unlock(&cpu_buffer->lock); | |
70255b5e | 1592 | local_irq_restore(flags); |
7a8e76a3 SR |
1593 | } |
1594 | ||
1595 | /** | |
1596 | * ring_buffer_reset - reset a ring buffer | |
1597 | * @buffer: The ring buffer to reset all cpu buffers | |
1598 | */ | |
1599 | void ring_buffer_reset(struct ring_buffer *buffer) | |
1600 | { | |
1601 | unsigned long flags; | |
1602 | int cpu; | |
1603 | ||
1604 | ring_buffer_lock(buffer, &flags); | |
1605 | ||
1606 | for_each_buffer_cpu(buffer, cpu) | |
1607 | rb_reset_cpu(buffer->buffers[cpu]); | |
1608 | ||
1609 | ring_buffer_unlock(buffer, flags); | |
1610 | } | |
1611 | ||
1612 | /** | |
1613 | * rind_buffer_empty - is the ring buffer empty? | |
1614 | * @buffer: The ring buffer to test | |
1615 | */ | |
1616 | int ring_buffer_empty(struct ring_buffer *buffer) | |
1617 | { | |
1618 | struct ring_buffer_per_cpu *cpu_buffer; | |
1619 | int cpu; | |
1620 | ||
1621 | /* yes this is racy, but if you don't like the race, lock the buffer */ | |
1622 | for_each_buffer_cpu(buffer, cpu) { | |
1623 | cpu_buffer = buffer->buffers[cpu]; | |
1624 | if (!rb_per_cpu_empty(cpu_buffer)) | |
1625 | return 0; | |
1626 | } | |
1627 | return 1; | |
1628 | } | |
1629 | ||
1630 | /** | |
1631 | * ring_buffer_empty_cpu - is a cpu buffer of a ring buffer empty? | |
1632 | * @buffer: The ring buffer | |
1633 | * @cpu: The CPU buffer to test | |
1634 | */ | |
1635 | int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) | |
1636 | { | |
1637 | struct ring_buffer_per_cpu *cpu_buffer; | |
1638 | ||
1639 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1640 | return 1; | |
1641 | ||
1642 | cpu_buffer = buffer->buffers[cpu]; | |
1643 | return rb_per_cpu_empty(cpu_buffer); | |
1644 | } | |
1645 | ||
1646 | /** | |
1647 | * ring_buffer_swap_cpu - swap a CPU buffer between two ring buffers | |
1648 | * @buffer_a: One buffer to swap with | |
1649 | * @buffer_b: The other buffer to swap with | |
1650 | * | |
1651 | * This function is useful for tracers that want to take a "snapshot" | |
1652 | * of a CPU buffer and has another back up buffer lying around. | |
1653 | * it is expected that the tracer handles the cpu buffer not being | |
1654 | * used at the moment. | |
1655 | */ | |
1656 | int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, | |
1657 | struct ring_buffer *buffer_b, int cpu) | |
1658 | { | |
1659 | struct ring_buffer_per_cpu *cpu_buffer_a; | |
1660 | struct ring_buffer_per_cpu *cpu_buffer_b; | |
1661 | ||
1662 | if (!cpu_isset(cpu, buffer_a->cpumask) || | |
1663 | !cpu_isset(cpu, buffer_b->cpumask)) | |
1664 | return -EINVAL; | |
1665 | ||
1666 | /* At least make sure the two buffers are somewhat the same */ | |
1667 | if (buffer_a->size != buffer_b->size || | |
1668 | buffer_a->pages != buffer_b->pages) | |
1669 | return -EINVAL; | |
1670 | ||
1671 | cpu_buffer_a = buffer_a->buffers[cpu]; | |
1672 | cpu_buffer_b = buffer_b->buffers[cpu]; | |
1673 | ||
1674 | /* | |
1675 | * We can't do a synchronize_sched here because this | |
1676 | * function can be called in atomic context. | |
1677 | * Normally this will be called from the same CPU as cpu. | |
1678 | * If not it's up to the caller to protect this. | |
1679 | */ | |
1680 | atomic_inc(&cpu_buffer_a->record_disabled); | |
1681 | atomic_inc(&cpu_buffer_b->record_disabled); | |
1682 | ||
1683 | buffer_a->buffers[cpu] = cpu_buffer_b; | |
1684 | buffer_b->buffers[cpu] = cpu_buffer_a; | |
1685 | ||
1686 | cpu_buffer_b->buffer = buffer_a; | |
1687 | cpu_buffer_a->buffer = buffer_b; | |
1688 | ||
1689 | atomic_dec(&cpu_buffer_a->record_disabled); | |
1690 | atomic_dec(&cpu_buffer_b->record_disabled); | |
1691 | ||
1692 | return 0; | |
1693 | } | |
1694 |