]>
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 | ||
a3583244 SR |
19 | #include "trace.h" |
20 | ||
21 | /* Global flag to disable all recording to ring buffers */ | |
22 | static int ring_buffers_off __read_mostly; | |
23 | ||
24 | /** | |
25 | * tracing_on - enable all tracing buffers | |
26 | * | |
27 | * This function enables all tracing buffers that may have been | |
28 | * disabled with tracing_off. | |
29 | */ | |
30 | void tracing_on(void) | |
31 | { | |
32 | ring_buffers_off = 0; | |
33 | } | |
34 | ||
35 | /** | |
36 | * tracing_off - turn off all tracing buffers | |
37 | * | |
38 | * This function stops all tracing buffers from recording data. | |
39 | * It does not disable any overhead the tracers themselves may | |
40 | * be causing. This function simply causes all recording to | |
41 | * the ring buffers to fail. | |
42 | */ | |
43 | void tracing_off(void) | |
44 | { | |
45 | ring_buffers_off = 1; | |
46 | } | |
47 | ||
7a8e76a3 SR |
48 | /* Up this if you want to test the TIME_EXTENTS and normalization */ |
49 | #define DEBUG_SHIFT 0 | |
50 | ||
51 | /* FIXME!!! */ | |
52 | u64 ring_buffer_time_stamp(int cpu) | |
53 | { | |
47e74f2b SR |
54 | u64 time; |
55 | ||
56 | preempt_disable_notrace(); | |
7a8e76a3 | 57 | /* shift to debug/test normalization and TIME_EXTENTS */ |
47e74f2b SR |
58 | time = sched_clock() << DEBUG_SHIFT; |
59 | preempt_enable_notrace(); | |
60 | ||
61 | return time; | |
7a8e76a3 SR |
62 | } |
63 | ||
64 | void ring_buffer_normalize_time_stamp(int cpu, u64 *ts) | |
65 | { | |
66 | /* Just stupid testing the normalize function and deltas */ | |
67 | *ts >>= DEBUG_SHIFT; | |
68 | } | |
69 | ||
70 | #define RB_EVNT_HDR_SIZE (sizeof(struct ring_buffer_event)) | |
71 | #define RB_ALIGNMENT_SHIFT 2 | |
72 | #define RB_ALIGNMENT (1 << RB_ALIGNMENT_SHIFT) | |
73 | #define RB_MAX_SMALL_DATA 28 | |
74 | ||
75 | enum { | |
76 | RB_LEN_TIME_EXTEND = 8, | |
77 | RB_LEN_TIME_STAMP = 16, | |
78 | }; | |
79 | ||
80 | /* inline for ring buffer fast paths */ | |
81 | static inline unsigned | |
82 | rb_event_length(struct ring_buffer_event *event) | |
83 | { | |
84 | unsigned length; | |
85 | ||
86 | switch (event->type) { | |
87 | case RINGBUF_TYPE_PADDING: | |
88 | /* undefined */ | |
89 | return -1; | |
90 | ||
91 | case RINGBUF_TYPE_TIME_EXTEND: | |
92 | return RB_LEN_TIME_EXTEND; | |
93 | ||
94 | case RINGBUF_TYPE_TIME_STAMP: | |
95 | return RB_LEN_TIME_STAMP; | |
96 | ||
97 | case RINGBUF_TYPE_DATA: | |
98 | if (event->len) | |
99 | length = event->len << RB_ALIGNMENT_SHIFT; | |
100 | else | |
101 | length = event->array[0]; | |
102 | return length + RB_EVNT_HDR_SIZE; | |
103 | default: | |
104 | BUG(); | |
105 | } | |
106 | /* not hit */ | |
107 | return 0; | |
108 | } | |
109 | ||
110 | /** | |
111 | * ring_buffer_event_length - return the length of the event | |
112 | * @event: the event to get the length of | |
113 | */ | |
114 | unsigned ring_buffer_event_length(struct ring_buffer_event *event) | |
115 | { | |
116 | return rb_event_length(event); | |
117 | } | |
118 | ||
119 | /* inline for ring buffer fast paths */ | |
120 | static inline void * | |
121 | rb_event_data(struct ring_buffer_event *event) | |
122 | { | |
123 | BUG_ON(event->type != RINGBUF_TYPE_DATA); | |
124 | /* If length is in len field, then array[0] has the data */ | |
125 | if (event->len) | |
126 | return (void *)&event->array[0]; | |
127 | /* Otherwise length is in array[0] and array[1] has the data */ | |
128 | return (void *)&event->array[1]; | |
129 | } | |
130 | ||
131 | /** | |
132 | * ring_buffer_event_data - return the data of the event | |
133 | * @event: the event to get the data from | |
134 | */ | |
135 | void *ring_buffer_event_data(struct ring_buffer_event *event) | |
136 | { | |
137 | return rb_event_data(event); | |
138 | } | |
139 | ||
140 | #define for_each_buffer_cpu(buffer, cpu) \ | |
141 | for_each_cpu_mask(cpu, buffer->cpumask) | |
142 | ||
143 | #define TS_SHIFT 27 | |
144 | #define TS_MASK ((1ULL << TS_SHIFT) - 1) | |
145 | #define TS_DELTA_TEST (~TS_MASK) | |
146 | ||
147 | /* | |
148 | * This hack stolen from mm/slob.c. | |
149 | * We can store per page timing information in the page frame of the page. | |
150 | * Thanks to Peter Zijlstra for suggesting this idea. | |
151 | */ | |
152 | struct buffer_page { | |
e4c2ce82 | 153 | u64 time_stamp; /* page time stamp */ |
bf41a158 SR |
154 | local_t write; /* index for next write */ |
155 | local_t commit; /* write commited index */ | |
6f807acd | 156 | unsigned read; /* index for next read */ |
e4c2ce82 SR |
157 | struct list_head list; /* list of free pages */ |
158 | void *page; /* Actual data page */ | |
7a8e76a3 SR |
159 | }; |
160 | ||
ed56829c SR |
161 | /* |
162 | * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing | |
163 | * this issue out. | |
164 | */ | |
165 | static inline void free_buffer_page(struct buffer_page *bpage) | |
166 | { | |
e4c2ce82 | 167 | if (bpage->page) |
6ae2a076 | 168 | free_page((unsigned long)bpage->page); |
e4c2ce82 | 169 | kfree(bpage); |
ed56829c SR |
170 | } |
171 | ||
7a8e76a3 SR |
172 | /* |
173 | * We need to fit the time_stamp delta into 27 bits. | |
174 | */ | |
175 | static inline int test_time_stamp(u64 delta) | |
176 | { | |
177 | if (delta & TS_DELTA_TEST) | |
178 | return 1; | |
179 | return 0; | |
180 | } | |
181 | ||
182 | #define BUF_PAGE_SIZE PAGE_SIZE | |
183 | ||
184 | /* | |
185 | * head_page == tail_page && head == tail then buffer is empty. | |
186 | */ | |
187 | struct ring_buffer_per_cpu { | |
188 | int cpu; | |
189 | struct ring_buffer *buffer; | |
190 | spinlock_t lock; | |
191 | struct lock_class_key lock_key; | |
192 | struct list_head pages; | |
6f807acd SR |
193 | struct buffer_page *head_page; /* read from head */ |
194 | struct buffer_page *tail_page; /* write to tail */ | |
bf41a158 | 195 | struct buffer_page *commit_page; /* commited pages */ |
d769041f | 196 | struct buffer_page *reader_page; |
7a8e76a3 SR |
197 | unsigned long overrun; |
198 | unsigned long entries; | |
199 | u64 write_stamp; | |
200 | u64 read_stamp; | |
201 | atomic_t record_disabled; | |
202 | }; | |
203 | ||
204 | struct ring_buffer { | |
205 | unsigned long size; | |
206 | unsigned pages; | |
207 | unsigned flags; | |
208 | int cpus; | |
209 | cpumask_t cpumask; | |
210 | atomic_t record_disabled; | |
211 | ||
212 | struct mutex mutex; | |
213 | ||
214 | struct ring_buffer_per_cpu **buffers; | |
215 | }; | |
216 | ||
217 | struct ring_buffer_iter { | |
218 | struct ring_buffer_per_cpu *cpu_buffer; | |
219 | unsigned long head; | |
220 | struct buffer_page *head_page; | |
221 | u64 read_stamp; | |
222 | }; | |
223 | ||
bf41a158 SR |
224 | #define RB_WARN_ON(buffer, cond) \ |
225 | do { \ | |
226 | if (unlikely(cond)) { \ | |
227 | atomic_inc(&buffer->record_disabled); \ | |
228 | WARN_ON(1); \ | |
229 | } \ | |
230 | } while (0) | |
231 | ||
232 | #define RB_WARN_ON_RET(buffer, cond) \ | |
233 | do { \ | |
234 | if (unlikely(cond)) { \ | |
235 | atomic_inc(&buffer->record_disabled); \ | |
236 | WARN_ON(1); \ | |
237 | return -1; \ | |
238 | } \ | |
239 | } while (0) | |
240 | ||
241 | #define RB_WARN_ON_ONCE(buffer, cond) \ | |
242 | do { \ | |
243 | static int once; \ | |
244 | if (unlikely(cond) && !once) { \ | |
245 | once++; \ | |
246 | atomic_inc(&buffer->record_disabled); \ | |
247 | WARN_ON(1); \ | |
248 | } \ | |
249 | } while (0) | |
7a8e76a3 SR |
250 | |
251 | /** | |
252 | * check_pages - integrity check of buffer pages | |
253 | * @cpu_buffer: CPU buffer with pages to test | |
254 | * | |
255 | * As a safty measure we check to make sure the data pages have not | |
256 | * been corrupted. | |
257 | */ | |
258 | static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) | |
259 | { | |
260 | struct list_head *head = &cpu_buffer->pages; | |
261 | struct buffer_page *page, *tmp; | |
262 | ||
bf41a158 SR |
263 | RB_WARN_ON_RET(cpu_buffer, head->next->prev != head); |
264 | RB_WARN_ON_RET(cpu_buffer, head->prev->next != head); | |
7a8e76a3 SR |
265 | |
266 | list_for_each_entry_safe(page, tmp, head, list) { | |
bf41a158 SR |
267 | RB_WARN_ON_RET(cpu_buffer, |
268 | page->list.next->prev != &page->list); | |
269 | RB_WARN_ON_RET(cpu_buffer, | |
270 | page->list.prev->next != &page->list); | |
7a8e76a3 SR |
271 | } |
272 | ||
273 | return 0; | |
274 | } | |
275 | ||
7a8e76a3 SR |
276 | static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, |
277 | unsigned nr_pages) | |
278 | { | |
279 | struct list_head *head = &cpu_buffer->pages; | |
280 | struct buffer_page *page, *tmp; | |
281 | unsigned long addr; | |
282 | LIST_HEAD(pages); | |
283 | unsigned i; | |
284 | ||
285 | for (i = 0; i < nr_pages; i++) { | |
e4c2ce82 | 286 | page = kzalloc_node(ALIGN(sizeof(*page), cache_line_size()), |
aa1e0e3b | 287 | GFP_KERNEL, cpu_to_node(cpu_buffer->cpu)); |
e4c2ce82 SR |
288 | if (!page) |
289 | goto free_pages; | |
290 | list_add(&page->list, &pages); | |
291 | ||
7a8e76a3 SR |
292 | addr = __get_free_page(GFP_KERNEL); |
293 | if (!addr) | |
294 | goto free_pages; | |
e4c2ce82 | 295 | page->page = (void *)addr; |
7a8e76a3 SR |
296 | } |
297 | ||
298 | list_splice(&pages, head); | |
299 | ||
300 | rb_check_pages(cpu_buffer); | |
301 | ||
302 | return 0; | |
303 | ||
304 | free_pages: | |
305 | list_for_each_entry_safe(page, tmp, &pages, list) { | |
306 | list_del_init(&page->list); | |
ed56829c | 307 | free_buffer_page(page); |
7a8e76a3 SR |
308 | } |
309 | return -ENOMEM; | |
310 | } | |
311 | ||
312 | static struct ring_buffer_per_cpu * | |
313 | rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu) | |
314 | { | |
315 | struct ring_buffer_per_cpu *cpu_buffer; | |
e4c2ce82 | 316 | struct buffer_page *page; |
d769041f | 317 | unsigned long addr; |
7a8e76a3 SR |
318 | int ret; |
319 | ||
320 | cpu_buffer = kzalloc_node(ALIGN(sizeof(*cpu_buffer), cache_line_size()), | |
321 | GFP_KERNEL, cpu_to_node(cpu)); | |
322 | if (!cpu_buffer) | |
323 | return NULL; | |
324 | ||
325 | cpu_buffer->cpu = cpu; | |
326 | cpu_buffer->buffer = buffer; | |
327 | spin_lock_init(&cpu_buffer->lock); | |
328 | INIT_LIST_HEAD(&cpu_buffer->pages); | |
329 | ||
e4c2ce82 SR |
330 | page = kzalloc_node(ALIGN(sizeof(*page), cache_line_size()), |
331 | GFP_KERNEL, cpu_to_node(cpu)); | |
332 | if (!page) | |
333 | goto fail_free_buffer; | |
334 | ||
335 | cpu_buffer->reader_page = page; | |
d769041f SR |
336 | addr = __get_free_page(GFP_KERNEL); |
337 | if (!addr) | |
e4c2ce82 SR |
338 | goto fail_free_reader; |
339 | page->page = (void *)addr; | |
340 | ||
d769041f | 341 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); |
d769041f | 342 | |
7a8e76a3 SR |
343 | ret = rb_allocate_pages(cpu_buffer, buffer->pages); |
344 | if (ret < 0) | |
d769041f | 345 | goto fail_free_reader; |
7a8e76a3 SR |
346 | |
347 | cpu_buffer->head_page | |
348 | = list_entry(cpu_buffer->pages.next, struct buffer_page, list); | |
bf41a158 | 349 | cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; |
7a8e76a3 SR |
350 | |
351 | return cpu_buffer; | |
352 | ||
d769041f SR |
353 | fail_free_reader: |
354 | free_buffer_page(cpu_buffer->reader_page); | |
355 | ||
7a8e76a3 SR |
356 | fail_free_buffer: |
357 | kfree(cpu_buffer); | |
358 | return NULL; | |
359 | } | |
360 | ||
361 | static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) | |
362 | { | |
363 | struct list_head *head = &cpu_buffer->pages; | |
364 | struct buffer_page *page, *tmp; | |
365 | ||
d769041f SR |
366 | list_del_init(&cpu_buffer->reader_page->list); |
367 | free_buffer_page(cpu_buffer->reader_page); | |
368 | ||
7a8e76a3 SR |
369 | list_for_each_entry_safe(page, tmp, head, list) { |
370 | list_del_init(&page->list); | |
ed56829c | 371 | free_buffer_page(page); |
7a8e76a3 SR |
372 | } |
373 | kfree(cpu_buffer); | |
374 | } | |
375 | ||
a7b13743 SR |
376 | /* |
377 | * Causes compile errors if the struct buffer_page gets bigger | |
378 | * than the struct page. | |
379 | */ | |
380 | extern int ring_buffer_page_too_big(void); | |
381 | ||
7a8e76a3 SR |
382 | /** |
383 | * ring_buffer_alloc - allocate a new ring_buffer | |
384 | * @size: the size in bytes that is needed. | |
385 | * @flags: attributes to set for the ring buffer. | |
386 | * | |
387 | * Currently the only flag that is available is the RB_FL_OVERWRITE | |
388 | * flag. This flag means that the buffer will overwrite old data | |
389 | * when the buffer wraps. If this flag is not set, the buffer will | |
390 | * drop data when the tail hits the head. | |
391 | */ | |
392 | struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags) | |
393 | { | |
394 | struct ring_buffer *buffer; | |
395 | int bsize; | |
396 | int cpu; | |
397 | ||
a7b13743 SR |
398 | /* Paranoid! Optimizes out when all is well */ |
399 | if (sizeof(struct buffer_page) > sizeof(struct page)) | |
400 | ring_buffer_page_too_big(); | |
401 | ||
402 | ||
7a8e76a3 SR |
403 | /* keep it in its own cache line */ |
404 | buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()), | |
405 | GFP_KERNEL); | |
406 | if (!buffer) | |
407 | return NULL; | |
408 | ||
409 | buffer->pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); | |
410 | buffer->flags = flags; | |
411 | ||
412 | /* need at least two pages */ | |
413 | if (buffer->pages == 1) | |
414 | buffer->pages++; | |
415 | ||
416 | buffer->cpumask = cpu_possible_map; | |
417 | buffer->cpus = nr_cpu_ids; | |
418 | ||
419 | bsize = sizeof(void *) * nr_cpu_ids; | |
420 | buffer->buffers = kzalloc(ALIGN(bsize, cache_line_size()), | |
421 | GFP_KERNEL); | |
422 | if (!buffer->buffers) | |
423 | goto fail_free_buffer; | |
424 | ||
425 | for_each_buffer_cpu(buffer, cpu) { | |
426 | buffer->buffers[cpu] = | |
427 | rb_allocate_cpu_buffer(buffer, cpu); | |
428 | if (!buffer->buffers[cpu]) | |
429 | goto fail_free_buffers; | |
430 | } | |
431 | ||
432 | mutex_init(&buffer->mutex); | |
433 | ||
434 | return buffer; | |
435 | ||
436 | fail_free_buffers: | |
437 | for_each_buffer_cpu(buffer, cpu) { | |
438 | if (buffer->buffers[cpu]) | |
439 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
440 | } | |
441 | kfree(buffer->buffers); | |
442 | ||
443 | fail_free_buffer: | |
444 | kfree(buffer); | |
445 | return NULL; | |
446 | } | |
447 | ||
448 | /** | |
449 | * ring_buffer_free - free a ring buffer. | |
450 | * @buffer: the buffer to free. | |
451 | */ | |
452 | void | |
453 | ring_buffer_free(struct ring_buffer *buffer) | |
454 | { | |
455 | int cpu; | |
456 | ||
457 | for_each_buffer_cpu(buffer, cpu) | |
458 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
459 | ||
460 | kfree(buffer); | |
461 | } | |
462 | ||
463 | static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer); | |
464 | ||
465 | static void | |
466 | rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages) | |
467 | { | |
468 | struct buffer_page *page; | |
469 | struct list_head *p; | |
470 | unsigned i; | |
471 | ||
472 | atomic_inc(&cpu_buffer->record_disabled); | |
473 | synchronize_sched(); | |
474 | ||
475 | for (i = 0; i < nr_pages; i++) { | |
476 | BUG_ON(list_empty(&cpu_buffer->pages)); | |
477 | p = cpu_buffer->pages.next; | |
478 | page = list_entry(p, struct buffer_page, list); | |
479 | list_del_init(&page->list); | |
ed56829c | 480 | free_buffer_page(page); |
7a8e76a3 SR |
481 | } |
482 | BUG_ON(list_empty(&cpu_buffer->pages)); | |
483 | ||
484 | rb_reset_cpu(cpu_buffer); | |
485 | ||
486 | rb_check_pages(cpu_buffer); | |
487 | ||
488 | atomic_dec(&cpu_buffer->record_disabled); | |
489 | ||
490 | } | |
491 | ||
492 | static void | |
493 | rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer, | |
494 | struct list_head *pages, unsigned nr_pages) | |
495 | { | |
496 | struct buffer_page *page; | |
497 | struct list_head *p; | |
498 | unsigned i; | |
499 | ||
500 | atomic_inc(&cpu_buffer->record_disabled); | |
501 | synchronize_sched(); | |
502 | ||
503 | for (i = 0; i < nr_pages; i++) { | |
504 | BUG_ON(list_empty(pages)); | |
505 | p = pages->next; | |
506 | page = list_entry(p, struct buffer_page, list); | |
507 | list_del_init(&page->list); | |
508 | list_add_tail(&page->list, &cpu_buffer->pages); | |
509 | } | |
510 | rb_reset_cpu(cpu_buffer); | |
511 | ||
512 | rb_check_pages(cpu_buffer); | |
513 | ||
514 | atomic_dec(&cpu_buffer->record_disabled); | |
515 | } | |
516 | ||
517 | /** | |
518 | * ring_buffer_resize - resize the ring buffer | |
519 | * @buffer: the buffer to resize. | |
520 | * @size: the new size. | |
521 | * | |
522 | * The tracer is responsible for making sure that the buffer is | |
523 | * not being used while changing the size. | |
524 | * Note: We may be able to change the above requirement by using | |
525 | * RCU synchronizations. | |
526 | * | |
527 | * Minimum size is 2 * BUF_PAGE_SIZE. | |
528 | * | |
529 | * Returns -1 on failure. | |
530 | */ | |
531 | int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size) | |
532 | { | |
533 | struct ring_buffer_per_cpu *cpu_buffer; | |
534 | unsigned nr_pages, rm_pages, new_pages; | |
535 | struct buffer_page *page, *tmp; | |
536 | unsigned long buffer_size; | |
537 | unsigned long addr; | |
538 | LIST_HEAD(pages); | |
539 | int i, cpu; | |
540 | ||
ee51a1de IM |
541 | /* |
542 | * Always succeed at resizing a non-existent buffer: | |
543 | */ | |
544 | if (!buffer) | |
545 | return size; | |
546 | ||
7a8e76a3 SR |
547 | size = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
548 | size *= BUF_PAGE_SIZE; | |
549 | buffer_size = buffer->pages * BUF_PAGE_SIZE; | |
550 | ||
551 | /* we need a minimum of two pages */ | |
552 | if (size < BUF_PAGE_SIZE * 2) | |
553 | size = BUF_PAGE_SIZE * 2; | |
554 | ||
555 | if (size == buffer_size) | |
556 | return size; | |
557 | ||
558 | mutex_lock(&buffer->mutex); | |
559 | ||
560 | nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); | |
561 | ||
562 | if (size < buffer_size) { | |
563 | ||
564 | /* easy case, just free pages */ | |
565 | BUG_ON(nr_pages >= buffer->pages); | |
566 | ||
567 | rm_pages = buffer->pages - nr_pages; | |
568 | ||
569 | for_each_buffer_cpu(buffer, cpu) { | |
570 | cpu_buffer = buffer->buffers[cpu]; | |
571 | rb_remove_pages(cpu_buffer, rm_pages); | |
572 | } | |
573 | goto out; | |
574 | } | |
575 | ||
576 | /* | |
577 | * This is a bit more difficult. We only want to add pages | |
578 | * when we can allocate enough for all CPUs. We do this | |
579 | * by allocating all the pages and storing them on a local | |
580 | * link list. If we succeed in our allocation, then we | |
581 | * add these pages to the cpu_buffers. Otherwise we just free | |
582 | * them all and return -ENOMEM; | |
583 | */ | |
584 | BUG_ON(nr_pages <= buffer->pages); | |
585 | new_pages = nr_pages - buffer->pages; | |
586 | ||
587 | for_each_buffer_cpu(buffer, cpu) { | |
588 | for (i = 0; i < new_pages; i++) { | |
e4c2ce82 SR |
589 | page = kzalloc_node(ALIGN(sizeof(*page), |
590 | cache_line_size()), | |
591 | GFP_KERNEL, cpu_to_node(cpu)); | |
592 | if (!page) | |
593 | goto free_pages; | |
594 | list_add(&page->list, &pages); | |
7a8e76a3 SR |
595 | addr = __get_free_page(GFP_KERNEL); |
596 | if (!addr) | |
597 | goto free_pages; | |
e4c2ce82 | 598 | page->page = (void *)addr; |
7a8e76a3 SR |
599 | } |
600 | } | |
601 | ||
602 | for_each_buffer_cpu(buffer, cpu) { | |
603 | cpu_buffer = buffer->buffers[cpu]; | |
604 | rb_insert_pages(cpu_buffer, &pages, new_pages); | |
605 | } | |
606 | ||
607 | BUG_ON(!list_empty(&pages)); | |
608 | ||
609 | out: | |
610 | buffer->pages = nr_pages; | |
611 | mutex_unlock(&buffer->mutex); | |
612 | ||
613 | return size; | |
614 | ||
615 | free_pages: | |
616 | list_for_each_entry_safe(page, tmp, &pages, list) { | |
617 | list_del_init(&page->list); | |
ed56829c | 618 | free_buffer_page(page); |
7a8e76a3 | 619 | } |
641d2f63 | 620 | mutex_unlock(&buffer->mutex); |
7a8e76a3 SR |
621 | return -ENOMEM; |
622 | } | |
623 | ||
7a8e76a3 SR |
624 | static inline int rb_null_event(struct ring_buffer_event *event) |
625 | { | |
626 | return event->type == RINGBUF_TYPE_PADDING; | |
627 | } | |
628 | ||
6f807acd | 629 | static inline void *__rb_page_index(struct buffer_page *page, unsigned index) |
7a8e76a3 | 630 | { |
e4c2ce82 | 631 | return page->page + index; |
7a8e76a3 SR |
632 | } |
633 | ||
634 | static inline struct ring_buffer_event * | |
d769041f | 635 | rb_reader_event(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 636 | { |
6f807acd SR |
637 | return __rb_page_index(cpu_buffer->reader_page, |
638 | cpu_buffer->reader_page->read); | |
639 | } | |
640 | ||
641 | static inline struct ring_buffer_event * | |
642 | rb_head_event(struct ring_buffer_per_cpu *cpu_buffer) | |
643 | { | |
644 | return __rb_page_index(cpu_buffer->head_page, | |
645 | cpu_buffer->head_page->read); | |
7a8e76a3 SR |
646 | } |
647 | ||
648 | static inline struct ring_buffer_event * | |
649 | rb_iter_head_event(struct ring_buffer_iter *iter) | |
650 | { | |
6f807acd | 651 | return __rb_page_index(iter->head_page, iter->head); |
7a8e76a3 SR |
652 | } |
653 | ||
bf41a158 SR |
654 | static inline unsigned rb_page_write(struct buffer_page *bpage) |
655 | { | |
656 | return local_read(&bpage->write); | |
657 | } | |
658 | ||
659 | static inline unsigned rb_page_commit(struct buffer_page *bpage) | |
660 | { | |
661 | return local_read(&bpage->commit); | |
662 | } | |
663 | ||
664 | /* Size is determined by what has been commited */ | |
665 | static inline unsigned rb_page_size(struct buffer_page *bpage) | |
666 | { | |
667 | return rb_page_commit(bpage); | |
668 | } | |
669 | ||
670 | static inline unsigned | |
671 | rb_commit_index(struct ring_buffer_per_cpu *cpu_buffer) | |
672 | { | |
673 | return rb_page_commit(cpu_buffer->commit_page); | |
674 | } | |
675 | ||
676 | static inline unsigned rb_head_size(struct ring_buffer_per_cpu *cpu_buffer) | |
677 | { | |
678 | return rb_page_commit(cpu_buffer->head_page); | |
679 | } | |
680 | ||
7a8e76a3 SR |
681 | /* |
682 | * When the tail hits the head and the buffer is in overwrite mode, | |
683 | * the head jumps to the next page and all content on the previous | |
684 | * page is discarded. But before doing so, we update the overrun | |
685 | * variable of the buffer. | |
686 | */ | |
687 | static void rb_update_overflow(struct ring_buffer_per_cpu *cpu_buffer) | |
688 | { | |
689 | struct ring_buffer_event *event; | |
690 | unsigned long head; | |
691 | ||
692 | for (head = 0; head < rb_head_size(cpu_buffer); | |
693 | head += rb_event_length(event)) { | |
694 | ||
6f807acd | 695 | event = __rb_page_index(cpu_buffer->head_page, head); |
7a8e76a3 SR |
696 | BUG_ON(rb_null_event(event)); |
697 | /* Only count data entries */ | |
698 | if (event->type != RINGBUF_TYPE_DATA) | |
699 | continue; | |
700 | cpu_buffer->overrun++; | |
701 | cpu_buffer->entries--; | |
702 | } | |
703 | } | |
704 | ||
705 | static inline void rb_inc_page(struct ring_buffer_per_cpu *cpu_buffer, | |
706 | struct buffer_page **page) | |
707 | { | |
708 | struct list_head *p = (*page)->list.next; | |
709 | ||
710 | if (p == &cpu_buffer->pages) | |
711 | p = p->next; | |
712 | ||
713 | *page = list_entry(p, struct buffer_page, list); | |
714 | } | |
715 | ||
bf41a158 SR |
716 | static inline unsigned |
717 | rb_event_index(struct ring_buffer_event *event) | |
718 | { | |
719 | unsigned long addr = (unsigned long)event; | |
720 | ||
721 | return (addr & ~PAGE_MASK) - (PAGE_SIZE - BUF_PAGE_SIZE); | |
722 | } | |
723 | ||
724 | static inline int | |
725 | rb_is_commit(struct ring_buffer_per_cpu *cpu_buffer, | |
726 | struct ring_buffer_event *event) | |
727 | { | |
728 | unsigned long addr = (unsigned long)event; | |
729 | unsigned long index; | |
730 | ||
731 | index = rb_event_index(event); | |
732 | addr &= PAGE_MASK; | |
733 | ||
734 | return cpu_buffer->commit_page->page == (void *)addr && | |
735 | rb_commit_index(cpu_buffer) == index; | |
736 | } | |
737 | ||
7a8e76a3 | 738 | static inline void |
bf41a158 SR |
739 | rb_set_commit_event(struct ring_buffer_per_cpu *cpu_buffer, |
740 | struct ring_buffer_event *event) | |
7a8e76a3 | 741 | { |
bf41a158 SR |
742 | unsigned long addr = (unsigned long)event; |
743 | unsigned long index; | |
744 | ||
745 | index = rb_event_index(event); | |
746 | addr &= PAGE_MASK; | |
747 | ||
748 | while (cpu_buffer->commit_page->page != (void *)addr) { | |
749 | RB_WARN_ON(cpu_buffer, | |
750 | cpu_buffer->commit_page == cpu_buffer->tail_page); | |
751 | cpu_buffer->commit_page->commit = | |
752 | cpu_buffer->commit_page->write; | |
753 | rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); | |
754 | cpu_buffer->write_stamp = cpu_buffer->commit_page->time_stamp; | |
755 | } | |
756 | ||
757 | /* Now set the commit to the event's index */ | |
758 | local_set(&cpu_buffer->commit_page->commit, index); | |
7a8e76a3 SR |
759 | } |
760 | ||
bf41a158 SR |
761 | static inline void |
762 | rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) | |
7a8e76a3 | 763 | { |
bf41a158 SR |
764 | /* |
765 | * We only race with interrupts and NMIs on this CPU. | |
766 | * If we own the commit event, then we can commit | |
767 | * all others that interrupted us, since the interruptions | |
768 | * are in stack format (they finish before they come | |
769 | * back to us). This allows us to do a simple loop to | |
770 | * assign the commit to the tail. | |
771 | */ | |
772 | while (cpu_buffer->commit_page != cpu_buffer->tail_page) { | |
773 | cpu_buffer->commit_page->commit = | |
774 | cpu_buffer->commit_page->write; | |
775 | rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); | |
776 | cpu_buffer->write_stamp = cpu_buffer->commit_page->time_stamp; | |
777 | /* add barrier to keep gcc from optimizing too much */ | |
778 | barrier(); | |
779 | } | |
780 | while (rb_commit_index(cpu_buffer) != | |
781 | rb_page_write(cpu_buffer->commit_page)) { | |
782 | cpu_buffer->commit_page->commit = | |
783 | cpu_buffer->commit_page->write; | |
784 | barrier(); | |
785 | } | |
7a8e76a3 SR |
786 | } |
787 | ||
d769041f | 788 | static void rb_reset_reader_page(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 789 | { |
d769041f | 790 | cpu_buffer->read_stamp = cpu_buffer->reader_page->time_stamp; |
6f807acd | 791 | cpu_buffer->reader_page->read = 0; |
d769041f SR |
792 | } |
793 | ||
794 | static inline void rb_inc_iter(struct ring_buffer_iter *iter) | |
795 | { | |
796 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
797 | ||
798 | /* | |
799 | * The iterator could be on the reader page (it starts there). | |
800 | * But the head could have moved, since the reader was | |
801 | * found. Check for this case and assign the iterator | |
802 | * to the head page instead of next. | |
803 | */ | |
804 | if (iter->head_page == cpu_buffer->reader_page) | |
805 | iter->head_page = cpu_buffer->head_page; | |
806 | else | |
807 | rb_inc_page(cpu_buffer, &iter->head_page); | |
808 | ||
7a8e76a3 SR |
809 | iter->read_stamp = iter->head_page->time_stamp; |
810 | iter->head = 0; | |
811 | } | |
812 | ||
813 | /** | |
814 | * ring_buffer_update_event - update event type and data | |
815 | * @event: the even to update | |
816 | * @type: the type of event | |
817 | * @length: the size of the event field in the ring buffer | |
818 | * | |
819 | * Update the type and data fields of the event. The length | |
820 | * is the actual size that is written to the ring buffer, | |
821 | * and with this, we can determine what to place into the | |
822 | * data field. | |
823 | */ | |
824 | static inline void | |
825 | rb_update_event(struct ring_buffer_event *event, | |
826 | unsigned type, unsigned length) | |
827 | { | |
828 | event->type = type; | |
829 | ||
830 | switch (type) { | |
831 | ||
832 | case RINGBUF_TYPE_PADDING: | |
833 | break; | |
834 | ||
835 | case RINGBUF_TYPE_TIME_EXTEND: | |
836 | event->len = | |
837 | (RB_LEN_TIME_EXTEND + (RB_ALIGNMENT-1)) | |
838 | >> RB_ALIGNMENT_SHIFT; | |
839 | break; | |
840 | ||
841 | case RINGBUF_TYPE_TIME_STAMP: | |
842 | event->len = | |
843 | (RB_LEN_TIME_STAMP + (RB_ALIGNMENT-1)) | |
844 | >> RB_ALIGNMENT_SHIFT; | |
845 | break; | |
846 | ||
847 | case RINGBUF_TYPE_DATA: | |
848 | length -= RB_EVNT_HDR_SIZE; | |
849 | if (length > RB_MAX_SMALL_DATA) { | |
850 | event->len = 0; | |
851 | event->array[0] = length; | |
852 | } else | |
853 | event->len = | |
854 | (length + (RB_ALIGNMENT-1)) | |
855 | >> RB_ALIGNMENT_SHIFT; | |
856 | break; | |
857 | default: | |
858 | BUG(); | |
859 | } | |
860 | } | |
861 | ||
862 | static inline unsigned rb_calculate_event_length(unsigned length) | |
863 | { | |
864 | struct ring_buffer_event event; /* Used only for sizeof array */ | |
865 | ||
866 | /* zero length can cause confusions */ | |
867 | if (!length) | |
868 | length = 1; | |
869 | ||
870 | if (length > RB_MAX_SMALL_DATA) | |
871 | length += sizeof(event.array[0]); | |
872 | ||
873 | length += RB_EVNT_HDR_SIZE; | |
874 | length = ALIGN(length, RB_ALIGNMENT); | |
875 | ||
876 | return length; | |
877 | } | |
878 | ||
879 | static struct ring_buffer_event * | |
880 | __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, | |
881 | unsigned type, unsigned long length, u64 *ts) | |
882 | { | |
d769041f | 883 | struct buffer_page *tail_page, *head_page, *reader_page; |
bf41a158 | 884 | unsigned long tail, write; |
7a8e76a3 SR |
885 | struct ring_buffer *buffer = cpu_buffer->buffer; |
886 | struct ring_buffer_event *event; | |
bf41a158 | 887 | unsigned long flags; |
7a8e76a3 SR |
888 | |
889 | tail_page = cpu_buffer->tail_page; | |
bf41a158 SR |
890 | write = local_add_return(length, &tail_page->write); |
891 | tail = write - length; | |
7a8e76a3 | 892 | |
bf41a158 SR |
893 | /* See if we shot pass the end of this buffer page */ |
894 | if (write > BUF_PAGE_SIZE) { | |
7a8e76a3 SR |
895 | struct buffer_page *next_page = tail_page; |
896 | ||
bf41a158 SR |
897 | spin_lock_irqsave(&cpu_buffer->lock, flags); |
898 | ||
7a8e76a3 SR |
899 | rb_inc_page(cpu_buffer, &next_page); |
900 | ||
d769041f SR |
901 | head_page = cpu_buffer->head_page; |
902 | reader_page = cpu_buffer->reader_page; | |
903 | ||
904 | /* we grabbed the lock before incrementing */ | |
bf41a158 SR |
905 | RB_WARN_ON(cpu_buffer, next_page == reader_page); |
906 | ||
907 | /* | |
908 | * If for some reason, we had an interrupt storm that made | |
909 | * it all the way around the buffer, bail, and warn | |
910 | * about it. | |
911 | */ | |
912 | if (unlikely(next_page == cpu_buffer->commit_page)) { | |
913 | WARN_ON_ONCE(1); | |
914 | goto out_unlock; | |
915 | } | |
d769041f | 916 | |
7a8e76a3 | 917 | if (next_page == head_page) { |
d769041f | 918 | if (!(buffer->flags & RB_FL_OVERWRITE)) { |
bf41a158 SR |
919 | /* reset write */ |
920 | if (tail <= BUF_PAGE_SIZE) | |
921 | local_set(&tail_page->write, tail); | |
922 | goto out_unlock; | |
d769041f | 923 | } |
7a8e76a3 | 924 | |
bf41a158 SR |
925 | /* tail_page has not moved yet? */ |
926 | if (tail_page == cpu_buffer->tail_page) { | |
927 | /* count overflows */ | |
928 | rb_update_overflow(cpu_buffer); | |
929 | ||
930 | rb_inc_page(cpu_buffer, &head_page); | |
931 | cpu_buffer->head_page = head_page; | |
932 | cpu_buffer->head_page->read = 0; | |
933 | } | |
934 | } | |
7a8e76a3 | 935 | |
bf41a158 SR |
936 | /* |
937 | * If the tail page is still the same as what we think | |
938 | * it is, then it is up to us to update the tail | |
939 | * pointer. | |
940 | */ | |
941 | if (tail_page == cpu_buffer->tail_page) { | |
942 | local_set(&next_page->write, 0); | |
943 | local_set(&next_page->commit, 0); | |
944 | cpu_buffer->tail_page = next_page; | |
945 | ||
946 | /* reread the time stamp */ | |
947 | *ts = ring_buffer_time_stamp(cpu_buffer->cpu); | |
948 | cpu_buffer->tail_page->time_stamp = *ts; | |
7a8e76a3 SR |
949 | } |
950 | ||
bf41a158 SR |
951 | /* |
952 | * The actual tail page has moved forward. | |
953 | */ | |
954 | if (tail < BUF_PAGE_SIZE) { | |
955 | /* Mark the rest of the page with padding */ | |
6f807acd | 956 | event = __rb_page_index(tail_page, tail); |
7a8e76a3 SR |
957 | event->type = RINGBUF_TYPE_PADDING; |
958 | } | |
959 | ||
bf41a158 SR |
960 | if (tail <= BUF_PAGE_SIZE) |
961 | /* Set the write back to the previous setting */ | |
962 | local_set(&tail_page->write, tail); | |
963 | ||
964 | /* | |
965 | * If this was a commit entry that failed, | |
966 | * increment that too | |
967 | */ | |
968 | if (tail_page == cpu_buffer->commit_page && | |
969 | tail == rb_commit_index(cpu_buffer)) { | |
970 | rb_set_commit_to_write(cpu_buffer); | |
971 | } | |
972 | ||
973 | spin_unlock_irqrestore(&cpu_buffer->lock, flags); | |
974 | ||
975 | /* fail and let the caller try again */ | |
976 | return ERR_PTR(-EAGAIN); | |
7a8e76a3 SR |
977 | } |
978 | ||
bf41a158 SR |
979 | /* We reserved something on the buffer */ |
980 | ||
981 | BUG_ON(write > BUF_PAGE_SIZE); | |
7a8e76a3 | 982 | |
6f807acd | 983 | event = __rb_page_index(tail_page, tail); |
7a8e76a3 SR |
984 | rb_update_event(event, type, length); |
985 | ||
bf41a158 SR |
986 | /* |
987 | * If this is a commit and the tail is zero, then update | |
988 | * this page's time stamp. | |
989 | */ | |
990 | if (!tail && rb_is_commit(cpu_buffer, event)) | |
991 | cpu_buffer->commit_page->time_stamp = *ts; | |
992 | ||
7a8e76a3 | 993 | return event; |
bf41a158 SR |
994 | |
995 | out_unlock: | |
996 | spin_unlock_irqrestore(&cpu_buffer->lock, flags); | |
997 | return NULL; | |
7a8e76a3 SR |
998 | } |
999 | ||
1000 | static int | |
1001 | rb_add_time_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
1002 | u64 *ts, u64 *delta) | |
1003 | { | |
1004 | struct ring_buffer_event *event; | |
1005 | static int once; | |
bf41a158 | 1006 | int ret; |
7a8e76a3 SR |
1007 | |
1008 | if (unlikely(*delta > (1ULL << 59) && !once++)) { | |
1009 | printk(KERN_WARNING "Delta way too big! %llu" | |
1010 | " ts=%llu write stamp = %llu\n", | |
e2862c94 SR |
1011 | (unsigned long long)*delta, |
1012 | (unsigned long long)*ts, | |
1013 | (unsigned long long)cpu_buffer->write_stamp); | |
7a8e76a3 SR |
1014 | WARN_ON(1); |
1015 | } | |
1016 | ||
1017 | /* | |
1018 | * The delta is too big, we to add a | |
1019 | * new timestamp. | |
1020 | */ | |
1021 | event = __rb_reserve_next(cpu_buffer, | |
1022 | RINGBUF_TYPE_TIME_EXTEND, | |
1023 | RB_LEN_TIME_EXTEND, | |
1024 | ts); | |
1025 | if (!event) | |
bf41a158 | 1026 | return -EBUSY; |
7a8e76a3 | 1027 | |
bf41a158 SR |
1028 | if (PTR_ERR(event) == -EAGAIN) |
1029 | return -EAGAIN; | |
1030 | ||
1031 | /* Only a commited time event can update the write stamp */ | |
1032 | if (rb_is_commit(cpu_buffer, event)) { | |
1033 | /* | |
1034 | * If this is the first on the page, then we need to | |
1035 | * update the page itself, and just put in a zero. | |
1036 | */ | |
1037 | if (rb_event_index(event)) { | |
1038 | event->time_delta = *delta & TS_MASK; | |
1039 | event->array[0] = *delta >> TS_SHIFT; | |
1040 | } else { | |
1041 | cpu_buffer->commit_page->time_stamp = *ts; | |
1042 | event->time_delta = 0; | |
1043 | event->array[0] = 0; | |
1044 | } | |
7a8e76a3 | 1045 | cpu_buffer->write_stamp = *ts; |
bf41a158 SR |
1046 | /* let the caller know this was the commit */ |
1047 | ret = 1; | |
1048 | } else { | |
1049 | /* Darn, this is just wasted space */ | |
1050 | event->time_delta = 0; | |
1051 | event->array[0] = 0; | |
1052 | ret = 0; | |
7a8e76a3 SR |
1053 | } |
1054 | ||
bf41a158 SR |
1055 | *delta = 0; |
1056 | ||
1057 | return ret; | |
7a8e76a3 SR |
1058 | } |
1059 | ||
1060 | static struct ring_buffer_event * | |
1061 | rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer, | |
1062 | unsigned type, unsigned long length) | |
1063 | { | |
1064 | struct ring_buffer_event *event; | |
1065 | u64 ts, delta; | |
bf41a158 | 1066 | int commit = 0; |
818e3dd3 | 1067 | int nr_loops = 0; |
7a8e76a3 | 1068 | |
bf41a158 | 1069 | again: |
818e3dd3 SR |
1070 | /* |
1071 | * We allow for interrupts to reenter here and do a trace. | |
1072 | * If one does, it will cause this original code to loop | |
1073 | * back here. Even with heavy interrupts happening, this | |
1074 | * should only happen a few times in a row. If this happens | |
1075 | * 1000 times in a row, there must be either an interrupt | |
1076 | * storm or we have something buggy. | |
1077 | * Bail! | |
1078 | */ | |
1079 | if (unlikely(++nr_loops > 1000)) { | |
1080 | RB_WARN_ON(cpu_buffer, 1); | |
1081 | return NULL; | |
1082 | } | |
1083 | ||
7a8e76a3 SR |
1084 | ts = ring_buffer_time_stamp(cpu_buffer->cpu); |
1085 | ||
bf41a158 SR |
1086 | /* |
1087 | * Only the first commit can update the timestamp. | |
1088 | * Yes there is a race here. If an interrupt comes in | |
1089 | * just after the conditional and it traces too, then it | |
1090 | * will also check the deltas. More than one timestamp may | |
1091 | * also be made. But only the entry that did the actual | |
1092 | * commit will be something other than zero. | |
1093 | */ | |
1094 | if (cpu_buffer->tail_page == cpu_buffer->commit_page && | |
1095 | rb_page_write(cpu_buffer->tail_page) == | |
1096 | rb_commit_index(cpu_buffer)) { | |
1097 | ||
7a8e76a3 SR |
1098 | delta = ts - cpu_buffer->write_stamp; |
1099 | ||
bf41a158 SR |
1100 | /* make sure this delta is calculated here */ |
1101 | barrier(); | |
1102 | ||
1103 | /* Did the write stamp get updated already? */ | |
1104 | if (unlikely(ts < cpu_buffer->write_stamp)) | |
4143c5cb | 1105 | delta = 0; |
bf41a158 | 1106 | |
7a8e76a3 | 1107 | if (test_time_stamp(delta)) { |
7a8e76a3 | 1108 | |
bf41a158 SR |
1109 | commit = rb_add_time_stamp(cpu_buffer, &ts, &delta); |
1110 | ||
1111 | if (commit == -EBUSY) | |
7a8e76a3 | 1112 | return NULL; |
bf41a158 SR |
1113 | |
1114 | if (commit == -EAGAIN) | |
1115 | goto again; | |
1116 | ||
1117 | RB_WARN_ON(cpu_buffer, commit < 0); | |
7a8e76a3 | 1118 | } |
bf41a158 SR |
1119 | } else |
1120 | /* Non commits have zero deltas */ | |
7a8e76a3 | 1121 | delta = 0; |
7a8e76a3 SR |
1122 | |
1123 | event = __rb_reserve_next(cpu_buffer, type, length, &ts); | |
bf41a158 SR |
1124 | if (PTR_ERR(event) == -EAGAIN) |
1125 | goto again; | |
1126 | ||
1127 | if (!event) { | |
1128 | if (unlikely(commit)) | |
1129 | /* | |
1130 | * Ouch! We needed a timestamp and it was commited. But | |
1131 | * we didn't get our event reserved. | |
1132 | */ | |
1133 | rb_set_commit_to_write(cpu_buffer); | |
7a8e76a3 | 1134 | return NULL; |
bf41a158 | 1135 | } |
7a8e76a3 | 1136 | |
bf41a158 SR |
1137 | /* |
1138 | * If the timestamp was commited, make the commit our entry | |
1139 | * now so that we will update it when needed. | |
1140 | */ | |
1141 | if (commit) | |
1142 | rb_set_commit_event(cpu_buffer, event); | |
1143 | else if (!rb_is_commit(cpu_buffer, event)) | |
7a8e76a3 SR |
1144 | delta = 0; |
1145 | ||
1146 | event->time_delta = delta; | |
1147 | ||
1148 | return event; | |
1149 | } | |
1150 | ||
bf41a158 SR |
1151 | static DEFINE_PER_CPU(int, rb_need_resched); |
1152 | ||
7a8e76a3 SR |
1153 | /** |
1154 | * ring_buffer_lock_reserve - reserve a part of the buffer | |
1155 | * @buffer: the ring buffer to reserve from | |
1156 | * @length: the length of the data to reserve (excluding event header) | |
1157 | * @flags: a pointer to save the interrupt flags | |
1158 | * | |
1159 | * Returns a reseverd event on the ring buffer to copy directly to. | |
1160 | * The user of this interface will need to get the body to write into | |
1161 | * and can use the ring_buffer_event_data() interface. | |
1162 | * | |
1163 | * The length is the length of the data needed, not the event length | |
1164 | * which also includes the event header. | |
1165 | * | |
1166 | * Must be paired with ring_buffer_unlock_commit, unless NULL is returned. | |
1167 | * If NULL is returned, then nothing has been allocated or locked. | |
1168 | */ | |
1169 | struct ring_buffer_event * | |
1170 | ring_buffer_lock_reserve(struct ring_buffer *buffer, | |
1171 | unsigned long length, | |
1172 | unsigned long *flags) | |
1173 | { | |
1174 | struct ring_buffer_per_cpu *cpu_buffer; | |
1175 | struct ring_buffer_event *event; | |
bf41a158 | 1176 | int cpu, resched; |
7a8e76a3 | 1177 | |
a3583244 SR |
1178 | if (ring_buffers_off) |
1179 | return NULL; | |
1180 | ||
7a8e76a3 SR |
1181 | if (atomic_read(&buffer->record_disabled)) |
1182 | return NULL; | |
1183 | ||
bf41a158 SR |
1184 | /* If we are tracing schedule, we don't want to recurse */ |
1185 | resched = need_resched(); | |
1186 | preempt_disable_notrace(); | |
1187 | ||
7a8e76a3 SR |
1188 | cpu = raw_smp_processor_id(); |
1189 | ||
1190 | if (!cpu_isset(cpu, buffer->cpumask)) | |
d769041f | 1191 | goto out; |
7a8e76a3 SR |
1192 | |
1193 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 SR |
1194 | |
1195 | if (atomic_read(&cpu_buffer->record_disabled)) | |
d769041f | 1196 | goto out; |
7a8e76a3 SR |
1197 | |
1198 | length = rb_calculate_event_length(length); | |
1199 | if (length > BUF_PAGE_SIZE) | |
bf41a158 | 1200 | goto out; |
7a8e76a3 SR |
1201 | |
1202 | event = rb_reserve_next_event(cpu_buffer, RINGBUF_TYPE_DATA, length); | |
1203 | if (!event) | |
d769041f | 1204 | goto out; |
7a8e76a3 | 1205 | |
bf41a158 SR |
1206 | /* |
1207 | * Need to store resched state on this cpu. | |
1208 | * Only the first needs to. | |
1209 | */ | |
1210 | ||
1211 | if (preempt_count() == 1) | |
1212 | per_cpu(rb_need_resched, cpu) = resched; | |
1213 | ||
7a8e76a3 SR |
1214 | return event; |
1215 | ||
d769041f | 1216 | out: |
bf41a158 | 1217 | if (resched) |
4f5a7f40 | 1218 | preempt_enable_no_resched_notrace(); |
bf41a158 SR |
1219 | else |
1220 | preempt_enable_notrace(); | |
7a8e76a3 SR |
1221 | return NULL; |
1222 | } | |
1223 | ||
1224 | static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, | |
1225 | struct ring_buffer_event *event) | |
1226 | { | |
7a8e76a3 | 1227 | cpu_buffer->entries++; |
bf41a158 SR |
1228 | |
1229 | /* Only process further if we own the commit */ | |
1230 | if (!rb_is_commit(cpu_buffer, event)) | |
1231 | return; | |
1232 | ||
1233 | cpu_buffer->write_stamp += event->time_delta; | |
1234 | ||
1235 | rb_set_commit_to_write(cpu_buffer); | |
7a8e76a3 SR |
1236 | } |
1237 | ||
1238 | /** | |
1239 | * ring_buffer_unlock_commit - commit a reserved | |
1240 | * @buffer: The buffer to commit to | |
1241 | * @event: The event pointer to commit. | |
1242 | * @flags: the interrupt flags received from ring_buffer_lock_reserve. | |
1243 | * | |
1244 | * This commits the data to the ring buffer, and releases any locks held. | |
1245 | * | |
1246 | * Must be paired with ring_buffer_lock_reserve. | |
1247 | */ | |
1248 | int ring_buffer_unlock_commit(struct ring_buffer *buffer, | |
1249 | struct ring_buffer_event *event, | |
1250 | unsigned long flags) | |
1251 | { | |
1252 | struct ring_buffer_per_cpu *cpu_buffer; | |
1253 | int cpu = raw_smp_processor_id(); | |
1254 | ||
1255 | cpu_buffer = buffer->buffers[cpu]; | |
1256 | ||
7a8e76a3 SR |
1257 | rb_commit(cpu_buffer, event); |
1258 | ||
bf41a158 SR |
1259 | /* |
1260 | * Only the last preempt count needs to restore preemption. | |
1261 | */ | |
1262 | if (preempt_count() == 1) { | |
1263 | if (per_cpu(rb_need_resched, cpu)) | |
1264 | preempt_enable_no_resched_notrace(); | |
1265 | else | |
1266 | preempt_enable_notrace(); | |
1267 | } else | |
1268 | preempt_enable_no_resched_notrace(); | |
7a8e76a3 SR |
1269 | |
1270 | return 0; | |
1271 | } | |
1272 | ||
1273 | /** | |
1274 | * ring_buffer_write - write data to the buffer without reserving | |
1275 | * @buffer: The ring buffer to write to. | |
1276 | * @length: The length of the data being written (excluding the event header) | |
1277 | * @data: The data to write to the buffer. | |
1278 | * | |
1279 | * This is like ring_buffer_lock_reserve and ring_buffer_unlock_commit as | |
1280 | * one function. If you already have the data to write to the buffer, it | |
1281 | * may be easier to simply call this function. | |
1282 | * | |
1283 | * Note, like ring_buffer_lock_reserve, the length is the length of the data | |
1284 | * and not the length of the event which would hold the header. | |
1285 | */ | |
1286 | int ring_buffer_write(struct ring_buffer *buffer, | |
1287 | unsigned long length, | |
1288 | void *data) | |
1289 | { | |
1290 | struct ring_buffer_per_cpu *cpu_buffer; | |
1291 | struct ring_buffer_event *event; | |
bf41a158 | 1292 | unsigned long event_length; |
7a8e76a3 SR |
1293 | void *body; |
1294 | int ret = -EBUSY; | |
bf41a158 | 1295 | int cpu, resched; |
7a8e76a3 | 1296 | |
a3583244 SR |
1297 | if (ring_buffers_off) |
1298 | return -EBUSY; | |
1299 | ||
7a8e76a3 SR |
1300 | if (atomic_read(&buffer->record_disabled)) |
1301 | return -EBUSY; | |
1302 | ||
bf41a158 SR |
1303 | resched = need_resched(); |
1304 | preempt_disable_notrace(); | |
1305 | ||
7a8e76a3 SR |
1306 | cpu = raw_smp_processor_id(); |
1307 | ||
1308 | if (!cpu_isset(cpu, buffer->cpumask)) | |
d769041f | 1309 | goto out; |
7a8e76a3 SR |
1310 | |
1311 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 SR |
1312 | |
1313 | if (atomic_read(&cpu_buffer->record_disabled)) | |
1314 | goto out; | |
1315 | ||
1316 | event_length = rb_calculate_event_length(length); | |
1317 | event = rb_reserve_next_event(cpu_buffer, | |
1318 | RINGBUF_TYPE_DATA, event_length); | |
1319 | if (!event) | |
1320 | goto out; | |
1321 | ||
1322 | body = rb_event_data(event); | |
1323 | ||
1324 | memcpy(body, data, length); | |
1325 | ||
1326 | rb_commit(cpu_buffer, event); | |
1327 | ||
1328 | ret = 0; | |
1329 | out: | |
bf41a158 SR |
1330 | if (resched) |
1331 | preempt_enable_no_resched_notrace(); | |
1332 | else | |
1333 | preempt_enable_notrace(); | |
7a8e76a3 SR |
1334 | |
1335 | return ret; | |
1336 | } | |
1337 | ||
bf41a158 SR |
1338 | static inline int rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) |
1339 | { | |
1340 | struct buffer_page *reader = cpu_buffer->reader_page; | |
1341 | struct buffer_page *head = cpu_buffer->head_page; | |
1342 | struct buffer_page *commit = cpu_buffer->commit_page; | |
1343 | ||
1344 | return reader->read == rb_page_commit(reader) && | |
1345 | (commit == reader || | |
1346 | (commit == head && | |
1347 | head->read == rb_page_commit(commit))); | |
1348 | } | |
1349 | ||
7a8e76a3 SR |
1350 | /** |
1351 | * ring_buffer_record_disable - stop all writes into the buffer | |
1352 | * @buffer: The ring buffer to stop writes to. | |
1353 | * | |
1354 | * This prevents all writes to the buffer. Any attempt to write | |
1355 | * to the buffer after this will fail and return NULL. | |
1356 | * | |
1357 | * The caller should call synchronize_sched() after this. | |
1358 | */ | |
1359 | void ring_buffer_record_disable(struct ring_buffer *buffer) | |
1360 | { | |
1361 | atomic_inc(&buffer->record_disabled); | |
1362 | } | |
1363 | ||
1364 | /** | |
1365 | * ring_buffer_record_enable - enable writes to the buffer | |
1366 | * @buffer: The ring buffer to enable writes | |
1367 | * | |
1368 | * Note, multiple disables will need the same number of enables | |
1369 | * to truely enable the writing (much like preempt_disable). | |
1370 | */ | |
1371 | void ring_buffer_record_enable(struct ring_buffer *buffer) | |
1372 | { | |
1373 | atomic_dec(&buffer->record_disabled); | |
1374 | } | |
1375 | ||
1376 | /** | |
1377 | * ring_buffer_record_disable_cpu - stop all writes into the cpu_buffer | |
1378 | * @buffer: The ring buffer to stop writes to. | |
1379 | * @cpu: The CPU buffer to stop | |
1380 | * | |
1381 | * This prevents all writes to the buffer. Any attempt to write | |
1382 | * to the buffer after this will fail and return NULL. | |
1383 | * | |
1384 | * The caller should call synchronize_sched() after this. | |
1385 | */ | |
1386 | void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu) | |
1387 | { | |
1388 | struct ring_buffer_per_cpu *cpu_buffer; | |
1389 | ||
1390 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1391 | return; | |
1392 | ||
1393 | cpu_buffer = buffer->buffers[cpu]; | |
1394 | atomic_inc(&cpu_buffer->record_disabled); | |
1395 | } | |
1396 | ||
1397 | /** | |
1398 | * ring_buffer_record_enable_cpu - enable writes to the buffer | |
1399 | * @buffer: The ring buffer to enable writes | |
1400 | * @cpu: The CPU to enable. | |
1401 | * | |
1402 | * Note, multiple disables will need the same number of enables | |
1403 | * to truely enable the writing (much like preempt_disable). | |
1404 | */ | |
1405 | void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu) | |
1406 | { | |
1407 | struct ring_buffer_per_cpu *cpu_buffer; | |
1408 | ||
1409 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1410 | return; | |
1411 | ||
1412 | cpu_buffer = buffer->buffers[cpu]; | |
1413 | atomic_dec(&cpu_buffer->record_disabled); | |
1414 | } | |
1415 | ||
1416 | /** | |
1417 | * ring_buffer_entries_cpu - get the number of entries in a cpu buffer | |
1418 | * @buffer: The ring buffer | |
1419 | * @cpu: The per CPU buffer to get the entries from. | |
1420 | */ | |
1421 | unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu) | |
1422 | { | |
1423 | struct ring_buffer_per_cpu *cpu_buffer; | |
1424 | ||
1425 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1426 | return 0; | |
1427 | ||
1428 | cpu_buffer = buffer->buffers[cpu]; | |
1429 | return cpu_buffer->entries; | |
1430 | } | |
1431 | ||
1432 | /** | |
1433 | * ring_buffer_overrun_cpu - get the number of overruns in a cpu_buffer | |
1434 | * @buffer: The ring buffer | |
1435 | * @cpu: The per CPU buffer to get the number of overruns from | |
1436 | */ | |
1437 | unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu) | |
1438 | { | |
1439 | struct ring_buffer_per_cpu *cpu_buffer; | |
1440 | ||
1441 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1442 | return 0; | |
1443 | ||
1444 | cpu_buffer = buffer->buffers[cpu]; | |
1445 | return cpu_buffer->overrun; | |
1446 | } | |
1447 | ||
1448 | /** | |
1449 | * ring_buffer_entries - get the number of entries in a buffer | |
1450 | * @buffer: The ring buffer | |
1451 | * | |
1452 | * Returns the total number of entries in the ring buffer | |
1453 | * (all CPU entries) | |
1454 | */ | |
1455 | unsigned long ring_buffer_entries(struct ring_buffer *buffer) | |
1456 | { | |
1457 | struct ring_buffer_per_cpu *cpu_buffer; | |
1458 | unsigned long entries = 0; | |
1459 | int cpu; | |
1460 | ||
1461 | /* if you care about this being correct, lock the buffer */ | |
1462 | for_each_buffer_cpu(buffer, cpu) { | |
1463 | cpu_buffer = buffer->buffers[cpu]; | |
1464 | entries += cpu_buffer->entries; | |
1465 | } | |
1466 | ||
1467 | return entries; | |
1468 | } | |
1469 | ||
1470 | /** | |
1471 | * ring_buffer_overrun_cpu - get the number of overruns in buffer | |
1472 | * @buffer: The ring buffer | |
1473 | * | |
1474 | * Returns the total number of overruns in the ring buffer | |
1475 | * (all CPU entries) | |
1476 | */ | |
1477 | unsigned long ring_buffer_overruns(struct ring_buffer *buffer) | |
1478 | { | |
1479 | struct ring_buffer_per_cpu *cpu_buffer; | |
1480 | unsigned long overruns = 0; | |
1481 | int cpu; | |
1482 | ||
1483 | /* if you care about this being correct, lock the buffer */ | |
1484 | for_each_buffer_cpu(buffer, cpu) { | |
1485 | cpu_buffer = buffer->buffers[cpu]; | |
1486 | overruns += cpu_buffer->overrun; | |
1487 | } | |
1488 | ||
1489 | return overruns; | |
1490 | } | |
1491 | ||
1492 | /** | |
1493 | * ring_buffer_iter_reset - reset an iterator | |
1494 | * @iter: The iterator to reset | |
1495 | * | |
1496 | * Resets the iterator, so that it will start from the beginning | |
1497 | * again. | |
1498 | */ | |
1499 | void ring_buffer_iter_reset(struct ring_buffer_iter *iter) | |
1500 | { | |
1501 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
1502 | ||
d769041f SR |
1503 | /* Iterator usage is expected to have record disabled */ |
1504 | if (list_empty(&cpu_buffer->reader_page->list)) { | |
1505 | iter->head_page = cpu_buffer->head_page; | |
6f807acd | 1506 | iter->head = cpu_buffer->head_page->read; |
d769041f SR |
1507 | } else { |
1508 | iter->head_page = cpu_buffer->reader_page; | |
6f807acd | 1509 | iter->head = cpu_buffer->reader_page->read; |
d769041f SR |
1510 | } |
1511 | if (iter->head) | |
1512 | iter->read_stamp = cpu_buffer->read_stamp; | |
1513 | else | |
1514 | iter->read_stamp = iter->head_page->time_stamp; | |
7a8e76a3 SR |
1515 | } |
1516 | ||
1517 | /** | |
1518 | * ring_buffer_iter_empty - check if an iterator has no more to read | |
1519 | * @iter: The iterator to check | |
1520 | */ | |
1521 | int ring_buffer_iter_empty(struct ring_buffer_iter *iter) | |
1522 | { | |
1523 | struct ring_buffer_per_cpu *cpu_buffer; | |
1524 | ||
1525 | cpu_buffer = iter->cpu_buffer; | |
1526 | ||
bf41a158 SR |
1527 | return iter->head_page == cpu_buffer->commit_page && |
1528 | iter->head == rb_commit_index(cpu_buffer); | |
7a8e76a3 SR |
1529 | } |
1530 | ||
1531 | static void | |
1532 | rb_update_read_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
1533 | struct ring_buffer_event *event) | |
1534 | { | |
1535 | u64 delta; | |
1536 | ||
1537 | switch (event->type) { | |
1538 | case RINGBUF_TYPE_PADDING: | |
1539 | return; | |
1540 | ||
1541 | case RINGBUF_TYPE_TIME_EXTEND: | |
1542 | delta = event->array[0]; | |
1543 | delta <<= TS_SHIFT; | |
1544 | delta += event->time_delta; | |
1545 | cpu_buffer->read_stamp += delta; | |
1546 | return; | |
1547 | ||
1548 | case RINGBUF_TYPE_TIME_STAMP: | |
1549 | /* FIXME: not implemented */ | |
1550 | return; | |
1551 | ||
1552 | case RINGBUF_TYPE_DATA: | |
1553 | cpu_buffer->read_stamp += event->time_delta; | |
1554 | return; | |
1555 | ||
1556 | default: | |
1557 | BUG(); | |
1558 | } | |
1559 | return; | |
1560 | } | |
1561 | ||
1562 | static void | |
1563 | rb_update_iter_read_stamp(struct ring_buffer_iter *iter, | |
1564 | struct ring_buffer_event *event) | |
1565 | { | |
1566 | u64 delta; | |
1567 | ||
1568 | switch (event->type) { | |
1569 | case RINGBUF_TYPE_PADDING: | |
1570 | return; | |
1571 | ||
1572 | case RINGBUF_TYPE_TIME_EXTEND: | |
1573 | delta = event->array[0]; | |
1574 | delta <<= TS_SHIFT; | |
1575 | delta += event->time_delta; | |
1576 | iter->read_stamp += delta; | |
1577 | return; | |
1578 | ||
1579 | case RINGBUF_TYPE_TIME_STAMP: | |
1580 | /* FIXME: not implemented */ | |
1581 | return; | |
1582 | ||
1583 | case RINGBUF_TYPE_DATA: | |
1584 | iter->read_stamp += event->time_delta; | |
1585 | return; | |
1586 | ||
1587 | default: | |
1588 | BUG(); | |
1589 | } | |
1590 | return; | |
1591 | } | |
1592 | ||
d769041f SR |
1593 | static struct buffer_page * |
1594 | rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) | |
7a8e76a3 | 1595 | { |
d769041f SR |
1596 | struct buffer_page *reader = NULL; |
1597 | unsigned long flags; | |
818e3dd3 | 1598 | int nr_loops = 0; |
d769041f SR |
1599 | |
1600 | spin_lock_irqsave(&cpu_buffer->lock, flags); | |
1601 | ||
1602 | again: | |
818e3dd3 SR |
1603 | /* |
1604 | * This should normally only loop twice. But because the | |
1605 | * start of the reader inserts an empty page, it causes | |
1606 | * a case where we will loop three times. There should be no | |
1607 | * reason to loop four times (that I know of). | |
1608 | */ | |
1609 | if (unlikely(++nr_loops > 3)) { | |
1610 | RB_WARN_ON(cpu_buffer, 1); | |
1611 | reader = NULL; | |
1612 | goto out; | |
1613 | } | |
1614 | ||
d769041f SR |
1615 | reader = cpu_buffer->reader_page; |
1616 | ||
1617 | /* If there's more to read, return this page */ | |
bf41a158 | 1618 | if (cpu_buffer->reader_page->read < rb_page_size(reader)) |
d769041f SR |
1619 | goto out; |
1620 | ||
1621 | /* Never should we have an index greater than the size */ | |
bf41a158 SR |
1622 | RB_WARN_ON(cpu_buffer, |
1623 | cpu_buffer->reader_page->read > rb_page_size(reader)); | |
d769041f SR |
1624 | |
1625 | /* check if we caught up to the tail */ | |
1626 | reader = NULL; | |
bf41a158 | 1627 | if (cpu_buffer->commit_page == cpu_buffer->reader_page) |
d769041f | 1628 | goto out; |
7a8e76a3 SR |
1629 | |
1630 | /* | |
d769041f SR |
1631 | * Splice the empty reader page into the list around the head. |
1632 | * Reset the reader page to size zero. | |
7a8e76a3 | 1633 | */ |
7a8e76a3 | 1634 | |
d769041f SR |
1635 | reader = cpu_buffer->head_page; |
1636 | cpu_buffer->reader_page->list.next = reader->list.next; | |
1637 | cpu_buffer->reader_page->list.prev = reader->list.prev; | |
bf41a158 SR |
1638 | |
1639 | local_set(&cpu_buffer->reader_page->write, 0); | |
1640 | local_set(&cpu_buffer->reader_page->commit, 0); | |
7a8e76a3 | 1641 | |
d769041f SR |
1642 | /* Make the reader page now replace the head */ |
1643 | reader->list.prev->next = &cpu_buffer->reader_page->list; | |
1644 | reader->list.next->prev = &cpu_buffer->reader_page->list; | |
7a8e76a3 SR |
1645 | |
1646 | /* | |
d769041f SR |
1647 | * If the tail is on the reader, then we must set the head |
1648 | * to the inserted page, otherwise we set it one before. | |
7a8e76a3 | 1649 | */ |
d769041f | 1650 | cpu_buffer->head_page = cpu_buffer->reader_page; |
7a8e76a3 | 1651 | |
bf41a158 | 1652 | if (cpu_buffer->commit_page != reader) |
d769041f SR |
1653 | rb_inc_page(cpu_buffer, &cpu_buffer->head_page); |
1654 | ||
1655 | /* Finally update the reader page to the new head */ | |
1656 | cpu_buffer->reader_page = reader; | |
1657 | rb_reset_reader_page(cpu_buffer); | |
1658 | ||
1659 | goto again; | |
1660 | ||
1661 | out: | |
1662 | spin_unlock_irqrestore(&cpu_buffer->lock, flags); | |
1663 | ||
1664 | return reader; | |
1665 | } | |
1666 | ||
1667 | static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer) | |
1668 | { | |
1669 | struct ring_buffer_event *event; | |
1670 | struct buffer_page *reader; | |
1671 | unsigned length; | |
1672 | ||
1673 | reader = rb_get_reader_page(cpu_buffer); | |
7a8e76a3 | 1674 | |
d769041f SR |
1675 | /* This function should not be called when buffer is empty */ |
1676 | BUG_ON(!reader); | |
7a8e76a3 | 1677 | |
d769041f SR |
1678 | event = rb_reader_event(cpu_buffer); |
1679 | ||
1680 | if (event->type == RINGBUF_TYPE_DATA) | |
1681 | cpu_buffer->entries--; | |
1682 | ||
1683 | rb_update_read_stamp(cpu_buffer, event); | |
1684 | ||
1685 | length = rb_event_length(event); | |
6f807acd | 1686 | cpu_buffer->reader_page->read += length; |
7a8e76a3 SR |
1687 | } |
1688 | ||
1689 | static void rb_advance_iter(struct ring_buffer_iter *iter) | |
1690 | { | |
1691 | struct ring_buffer *buffer; | |
1692 | struct ring_buffer_per_cpu *cpu_buffer; | |
1693 | struct ring_buffer_event *event; | |
1694 | unsigned length; | |
1695 | ||
1696 | cpu_buffer = iter->cpu_buffer; | |
1697 | buffer = cpu_buffer->buffer; | |
1698 | ||
1699 | /* | |
1700 | * Check if we are at the end of the buffer. | |
1701 | */ | |
bf41a158 SR |
1702 | if (iter->head >= rb_page_size(iter->head_page)) { |
1703 | BUG_ON(iter->head_page == cpu_buffer->commit_page); | |
d769041f | 1704 | rb_inc_iter(iter); |
7a8e76a3 SR |
1705 | return; |
1706 | } | |
1707 | ||
1708 | event = rb_iter_head_event(iter); | |
1709 | ||
1710 | length = rb_event_length(event); | |
1711 | ||
1712 | /* | |
1713 | * This should not be called to advance the header if we are | |
1714 | * at the tail of the buffer. | |
1715 | */ | |
bf41a158 SR |
1716 | BUG_ON((iter->head_page == cpu_buffer->commit_page) && |
1717 | (iter->head + length > rb_commit_index(cpu_buffer))); | |
7a8e76a3 SR |
1718 | |
1719 | rb_update_iter_read_stamp(iter, event); | |
1720 | ||
1721 | iter->head += length; | |
1722 | ||
1723 | /* check for end of page padding */ | |
bf41a158 SR |
1724 | if ((iter->head >= rb_page_size(iter->head_page)) && |
1725 | (iter->head_page != cpu_buffer->commit_page)) | |
7a8e76a3 SR |
1726 | rb_advance_iter(iter); |
1727 | } | |
1728 | ||
1729 | /** | |
1730 | * ring_buffer_peek - peek at the next event to be read | |
1731 | * @buffer: The ring buffer to read | |
1732 | * @cpu: The cpu to peak at | |
1733 | * @ts: The timestamp counter of this event. | |
1734 | * | |
1735 | * This will return the event that will be read next, but does | |
1736 | * not consume the data. | |
1737 | */ | |
1738 | struct ring_buffer_event * | |
1739 | ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) | |
1740 | { | |
1741 | struct ring_buffer_per_cpu *cpu_buffer; | |
1742 | struct ring_buffer_event *event; | |
d769041f | 1743 | struct buffer_page *reader; |
818e3dd3 | 1744 | int nr_loops = 0; |
7a8e76a3 SR |
1745 | |
1746 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1747 | return NULL; | |
1748 | ||
1749 | cpu_buffer = buffer->buffers[cpu]; | |
1750 | ||
1751 | again: | |
818e3dd3 SR |
1752 | /* |
1753 | * We repeat when a timestamp is encountered. It is possible | |
1754 | * to get multiple timestamps from an interrupt entering just | |
1755 | * as one timestamp is about to be written. The max times | |
1756 | * that this can happen is the number of nested interrupts we | |
1757 | * can have. Nesting 10 deep of interrupts is clearly | |
1758 | * an anomaly. | |
1759 | */ | |
1760 | if (unlikely(++nr_loops > 10)) { | |
1761 | RB_WARN_ON(cpu_buffer, 1); | |
1762 | return NULL; | |
1763 | } | |
1764 | ||
d769041f SR |
1765 | reader = rb_get_reader_page(cpu_buffer); |
1766 | if (!reader) | |
7a8e76a3 SR |
1767 | return NULL; |
1768 | ||
d769041f | 1769 | event = rb_reader_event(cpu_buffer); |
7a8e76a3 SR |
1770 | |
1771 | switch (event->type) { | |
1772 | case RINGBUF_TYPE_PADDING: | |
bf41a158 | 1773 | RB_WARN_ON(cpu_buffer, 1); |
d769041f SR |
1774 | rb_advance_reader(cpu_buffer); |
1775 | return NULL; | |
7a8e76a3 SR |
1776 | |
1777 | case RINGBUF_TYPE_TIME_EXTEND: | |
1778 | /* Internal data, OK to advance */ | |
d769041f | 1779 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
1780 | goto again; |
1781 | ||
1782 | case RINGBUF_TYPE_TIME_STAMP: | |
1783 | /* FIXME: not implemented */ | |
d769041f | 1784 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
1785 | goto again; |
1786 | ||
1787 | case RINGBUF_TYPE_DATA: | |
1788 | if (ts) { | |
1789 | *ts = cpu_buffer->read_stamp + event->time_delta; | |
1790 | ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts); | |
1791 | } | |
1792 | return event; | |
1793 | ||
1794 | default: | |
1795 | BUG(); | |
1796 | } | |
1797 | ||
1798 | return NULL; | |
1799 | } | |
1800 | ||
1801 | /** | |
1802 | * ring_buffer_iter_peek - peek at the next event to be read | |
1803 | * @iter: The ring buffer iterator | |
1804 | * @ts: The timestamp counter of this event. | |
1805 | * | |
1806 | * This will return the event that will be read next, but does | |
1807 | * not increment the iterator. | |
1808 | */ | |
1809 | struct ring_buffer_event * | |
1810 | ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) | |
1811 | { | |
1812 | struct ring_buffer *buffer; | |
1813 | struct ring_buffer_per_cpu *cpu_buffer; | |
1814 | struct ring_buffer_event *event; | |
818e3dd3 | 1815 | int nr_loops = 0; |
7a8e76a3 SR |
1816 | |
1817 | if (ring_buffer_iter_empty(iter)) | |
1818 | return NULL; | |
1819 | ||
1820 | cpu_buffer = iter->cpu_buffer; | |
1821 | buffer = cpu_buffer->buffer; | |
1822 | ||
1823 | again: | |
818e3dd3 SR |
1824 | /* |
1825 | * We repeat when a timestamp is encountered. It is possible | |
1826 | * to get multiple timestamps from an interrupt entering just | |
1827 | * as one timestamp is about to be written. The max times | |
1828 | * that this can happen is the number of nested interrupts we | |
1829 | * can have. Nesting 10 deep of interrupts is clearly | |
1830 | * an anomaly. | |
1831 | */ | |
1832 | if (unlikely(++nr_loops > 10)) { | |
1833 | RB_WARN_ON(cpu_buffer, 1); | |
1834 | return NULL; | |
1835 | } | |
1836 | ||
7a8e76a3 SR |
1837 | if (rb_per_cpu_empty(cpu_buffer)) |
1838 | return NULL; | |
1839 | ||
1840 | event = rb_iter_head_event(iter); | |
1841 | ||
1842 | switch (event->type) { | |
1843 | case RINGBUF_TYPE_PADDING: | |
d769041f | 1844 | rb_inc_iter(iter); |
7a8e76a3 SR |
1845 | goto again; |
1846 | ||
1847 | case RINGBUF_TYPE_TIME_EXTEND: | |
1848 | /* Internal data, OK to advance */ | |
1849 | rb_advance_iter(iter); | |
1850 | goto again; | |
1851 | ||
1852 | case RINGBUF_TYPE_TIME_STAMP: | |
1853 | /* FIXME: not implemented */ | |
1854 | rb_advance_iter(iter); | |
1855 | goto again; | |
1856 | ||
1857 | case RINGBUF_TYPE_DATA: | |
1858 | if (ts) { | |
1859 | *ts = iter->read_stamp + event->time_delta; | |
1860 | ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts); | |
1861 | } | |
1862 | return event; | |
1863 | ||
1864 | default: | |
1865 | BUG(); | |
1866 | } | |
1867 | ||
1868 | return NULL; | |
1869 | } | |
1870 | ||
1871 | /** | |
1872 | * ring_buffer_consume - return an event and consume it | |
1873 | * @buffer: The ring buffer to get the next event from | |
1874 | * | |
1875 | * Returns the next event in the ring buffer, and that event is consumed. | |
1876 | * Meaning, that sequential reads will keep returning a different event, | |
1877 | * and eventually empty the ring buffer if the producer is slower. | |
1878 | */ | |
1879 | struct ring_buffer_event * | |
1880 | ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts) | |
1881 | { | |
1882 | struct ring_buffer_per_cpu *cpu_buffer; | |
1883 | struct ring_buffer_event *event; | |
1884 | ||
1885 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1886 | return NULL; | |
1887 | ||
1888 | event = ring_buffer_peek(buffer, cpu, ts); | |
1889 | if (!event) | |
1890 | return NULL; | |
1891 | ||
1892 | cpu_buffer = buffer->buffers[cpu]; | |
d769041f | 1893 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
1894 | |
1895 | return event; | |
1896 | } | |
1897 | ||
1898 | /** | |
1899 | * ring_buffer_read_start - start a non consuming read of the buffer | |
1900 | * @buffer: The ring buffer to read from | |
1901 | * @cpu: The cpu buffer to iterate over | |
1902 | * | |
1903 | * This starts up an iteration through the buffer. It also disables | |
1904 | * the recording to the buffer until the reading is finished. | |
1905 | * This prevents the reading from being corrupted. This is not | |
1906 | * a consuming read, so a producer is not expected. | |
1907 | * | |
1908 | * Must be paired with ring_buffer_finish. | |
1909 | */ | |
1910 | struct ring_buffer_iter * | |
1911 | ring_buffer_read_start(struct ring_buffer *buffer, int cpu) | |
1912 | { | |
1913 | struct ring_buffer_per_cpu *cpu_buffer; | |
1914 | struct ring_buffer_iter *iter; | |
d769041f | 1915 | unsigned long flags; |
7a8e76a3 SR |
1916 | |
1917 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1918 | return NULL; | |
1919 | ||
1920 | iter = kmalloc(sizeof(*iter), GFP_KERNEL); | |
1921 | if (!iter) | |
1922 | return NULL; | |
1923 | ||
1924 | cpu_buffer = buffer->buffers[cpu]; | |
1925 | ||
1926 | iter->cpu_buffer = cpu_buffer; | |
1927 | ||
1928 | atomic_inc(&cpu_buffer->record_disabled); | |
1929 | synchronize_sched(); | |
1930 | ||
d769041f SR |
1931 | spin_lock_irqsave(&cpu_buffer->lock, flags); |
1932 | ring_buffer_iter_reset(iter); | |
1933 | spin_unlock_irqrestore(&cpu_buffer->lock, flags); | |
7a8e76a3 SR |
1934 | |
1935 | return iter; | |
1936 | } | |
1937 | ||
1938 | /** | |
1939 | * ring_buffer_finish - finish reading the iterator of the buffer | |
1940 | * @iter: The iterator retrieved by ring_buffer_start | |
1941 | * | |
1942 | * This re-enables the recording to the buffer, and frees the | |
1943 | * iterator. | |
1944 | */ | |
1945 | void | |
1946 | ring_buffer_read_finish(struct ring_buffer_iter *iter) | |
1947 | { | |
1948 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
1949 | ||
1950 | atomic_dec(&cpu_buffer->record_disabled); | |
1951 | kfree(iter); | |
1952 | } | |
1953 | ||
1954 | /** | |
1955 | * ring_buffer_read - read the next item in the ring buffer by the iterator | |
1956 | * @iter: The ring buffer iterator | |
1957 | * @ts: The time stamp of the event read. | |
1958 | * | |
1959 | * This reads the next event in the ring buffer and increments the iterator. | |
1960 | */ | |
1961 | struct ring_buffer_event * | |
1962 | ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) | |
1963 | { | |
1964 | struct ring_buffer_event *event; | |
1965 | ||
1966 | event = ring_buffer_iter_peek(iter, ts); | |
1967 | if (!event) | |
1968 | return NULL; | |
1969 | ||
1970 | rb_advance_iter(iter); | |
1971 | ||
1972 | return event; | |
1973 | } | |
1974 | ||
1975 | /** | |
1976 | * ring_buffer_size - return the size of the ring buffer (in bytes) | |
1977 | * @buffer: The ring buffer. | |
1978 | */ | |
1979 | unsigned long ring_buffer_size(struct ring_buffer *buffer) | |
1980 | { | |
1981 | return BUF_PAGE_SIZE * buffer->pages; | |
1982 | } | |
1983 | ||
1984 | static void | |
1985 | rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) | |
1986 | { | |
1987 | cpu_buffer->head_page | |
1988 | = list_entry(cpu_buffer->pages.next, struct buffer_page, list); | |
bf41a158 SR |
1989 | local_set(&cpu_buffer->head_page->write, 0); |
1990 | local_set(&cpu_buffer->head_page->commit, 0); | |
d769041f | 1991 | |
6f807acd | 1992 | cpu_buffer->head_page->read = 0; |
bf41a158 SR |
1993 | |
1994 | cpu_buffer->tail_page = cpu_buffer->head_page; | |
1995 | cpu_buffer->commit_page = cpu_buffer->head_page; | |
1996 | ||
1997 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); | |
1998 | local_set(&cpu_buffer->reader_page->write, 0); | |
1999 | local_set(&cpu_buffer->reader_page->commit, 0); | |
6f807acd | 2000 | cpu_buffer->reader_page->read = 0; |
7a8e76a3 | 2001 | |
7a8e76a3 SR |
2002 | cpu_buffer->overrun = 0; |
2003 | cpu_buffer->entries = 0; | |
2004 | } | |
2005 | ||
2006 | /** | |
2007 | * ring_buffer_reset_cpu - reset a ring buffer per CPU buffer | |
2008 | * @buffer: The ring buffer to reset a per cpu buffer of | |
2009 | * @cpu: The CPU buffer to be reset | |
2010 | */ | |
2011 | void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) | |
2012 | { | |
2013 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
2014 | unsigned long flags; | |
2015 | ||
2016 | if (!cpu_isset(cpu, buffer->cpumask)) | |
2017 | return; | |
2018 | ||
d769041f | 2019 | spin_lock_irqsave(&cpu_buffer->lock, flags); |
7a8e76a3 SR |
2020 | |
2021 | rb_reset_cpu(cpu_buffer); | |
2022 | ||
d769041f | 2023 | spin_unlock_irqrestore(&cpu_buffer->lock, flags); |
7a8e76a3 SR |
2024 | } |
2025 | ||
2026 | /** | |
2027 | * ring_buffer_reset - reset a ring buffer | |
2028 | * @buffer: The ring buffer to reset all cpu buffers | |
2029 | */ | |
2030 | void ring_buffer_reset(struct ring_buffer *buffer) | |
2031 | { | |
7a8e76a3 SR |
2032 | int cpu; |
2033 | ||
7a8e76a3 | 2034 | for_each_buffer_cpu(buffer, cpu) |
d769041f | 2035 | ring_buffer_reset_cpu(buffer, cpu); |
7a8e76a3 SR |
2036 | } |
2037 | ||
2038 | /** | |
2039 | * rind_buffer_empty - is the ring buffer empty? | |
2040 | * @buffer: The ring buffer to test | |
2041 | */ | |
2042 | int ring_buffer_empty(struct ring_buffer *buffer) | |
2043 | { | |
2044 | struct ring_buffer_per_cpu *cpu_buffer; | |
2045 | int cpu; | |
2046 | ||
2047 | /* yes this is racy, but if you don't like the race, lock the buffer */ | |
2048 | for_each_buffer_cpu(buffer, cpu) { | |
2049 | cpu_buffer = buffer->buffers[cpu]; | |
2050 | if (!rb_per_cpu_empty(cpu_buffer)) | |
2051 | return 0; | |
2052 | } | |
2053 | return 1; | |
2054 | } | |
2055 | ||
2056 | /** | |
2057 | * ring_buffer_empty_cpu - is a cpu buffer of a ring buffer empty? | |
2058 | * @buffer: The ring buffer | |
2059 | * @cpu: The CPU buffer to test | |
2060 | */ | |
2061 | int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) | |
2062 | { | |
2063 | struct ring_buffer_per_cpu *cpu_buffer; | |
2064 | ||
2065 | if (!cpu_isset(cpu, buffer->cpumask)) | |
2066 | return 1; | |
2067 | ||
2068 | cpu_buffer = buffer->buffers[cpu]; | |
2069 | return rb_per_cpu_empty(cpu_buffer); | |
2070 | } | |
2071 | ||
2072 | /** | |
2073 | * ring_buffer_swap_cpu - swap a CPU buffer between two ring buffers | |
2074 | * @buffer_a: One buffer to swap with | |
2075 | * @buffer_b: The other buffer to swap with | |
2076 | * | |
2077 | * This function is useful for tracers that want to take a "snapshot" | |
2078 | * of a CPU buffer and has another back up buffer lying around. | |
2079 | * it is expected that the tracer handles the cpu buffer not being | |
2080 | * used at the moment. | |
2081 | */ | |
2082 | int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, | |
2083 | struct ring_buffer *buffer_b, int cpu) | |
2084 | { | |
2085 | struct ring_buffer_per_cpu *cpu_buffer_a; | |
2086 | struct ring_buffer_per_cpu *cpu_buffer_b; | |
2087 | ||
2088 | if (!cpu_isset(cpu, buffer_a->cpumask) || | |
2089 | !cpu_isset(cpu, buffer_b->cpumask)) | |
2090 | return -EINVAL; | |
2091 | ||
2092 | /* At least make sure the two buffers are somewhat the same */ | |
2093 | if (buffer_a->size != buffer_b->size || | |
2094 | buffer_a->pages != buffer_b->pages) | |
2095 | return -EINVAL; | |
2096 | ||
2097 | cpu_buffer_a = buffer_a->buffers[cpu]; | |
2098 | cpu_buffer_b = buffer_b->buffers[cpu]; | |
2099 | ||
2100 | /* | |
2101 | * We can't do a synchronize_sched here because this | |
2102 | * function can be called in atomic context. | |
2103 | * Normally this will be called from the same CPU as cpu. | |
2104 | * If not it's up to the caller to protect this. | |
2105 | */ | |
2106 | atomic_inc(&cpu_buffer_a->record_disabled); | |
2107 | atomic_inc(&cpu_buffer_b->record_disabled); | |
2108 | ||
2109 | buffer_a->buffers[cpu] = cpu_buffer_b; | |
2110 | buffer_b->buffers[cpu] = cpu_buffer_a; | |
2111 | ||
2112 | cpu_buffer_b->buffer = buffer_a; | |
2113 | cpu_buffer_a->buffer = buffer_b; | |
2114 | ||
2115 | atomic_dec(&cpu_buffer_a->record_disabled); | |
2116 | atomic_dec(&cpu_buffer_b->record_disabled); | |
2117 | ||
2118 | return 0; | |
2119 | } | |
2120 | ||
a3583244 SR |
2121 | static ssize_t |
2122 | rb_simple_read(struct file *filp, char __user *ubuf, | |
2123 | size_t cnt, loff_t *ppos) | |
2124 | { | |
2125 | int *p = filp->private_data; | |
2126 | char buf[64]; | |
2127 | int r; | |
2128 | ||
2129 | /* !ring_buffers_off == tracing_on */ | |
2130 | r = sprintf(buf, "%d\n", !*p); | |
2131 | ||
2132 | return simple_read_from_buffer(ubuf, cnt, ppos, buf, r); | |
2133 | } | |
2134 | ||
2135 | static ssize_t | |
2136 | rb_simple_write(struct file *filp, const char __user *ubuf, | |
2137 | size_t cnt, loff_t *ppos) | |
2138 | { | |
2139 | int *p = filp->private_data; | |
2140 | char buf[64]; | |
2141 | long val; | |
2142 | int ret; | |
2143 | ||
2144 | if (cnt >= sizeof(buf)) | |
2145 | return -EINVAL; | |
2146 | ||
2147 | if (copy_from_user(&buf, ubuf, cnt)) | |
2148 | return -EFAULT; | |
2149 | ||
2150 | buf[cnt] = 0; | |
2151 | ||
2152 | ret = strict_strtoul(buf, 10, &val); | |
2153 | if (ret < 0) | |
2154 | return ret; | |
2155 | ||
2156 | /* !ring_buffers_off == tracing_on */ | |
2157 | *p = !val; | |
2158 | ||
2159 | (*ppos)++; | |
2160 | ||
2161 | return cnt; | |
2162 | } | |
2163 | ||
2164 | static struct file_operations rb_simple_fops = { | |
2165 | .open = tracing_open_generic, | |
2166 | .read = rb_simple_read, | |
2167 | .write = rb_simple_write, | |
2168 | }; | |
2169 | ||
2170 | ||
2171 | static __init int rb_init_debugfs(void) | |
2172 | { | |
2173 | struct dentry *d_tracer; | |
2174 | struct dentry *entry; | |
2175 | ||
2176 | d_tracer = tracing_init_dentry(); | |
2177 | ||
2178 | entry = debugfs_create_file("tracing_on", 0644, d_tracer, | |
2179 | &ring_buffers_off, &rb_simple_fops); | |
2180 | if (!entry) | |
2181 | pr_warning("Could not create debugfs 'tracing_on' entry\n"); | |
2182 | ||
2183 | return 0; | |
2184 | } | |
2185 | ||
2186 | fs_initcall(rb_init_debugfs); |