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Commit | Line | Data |
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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 | } | |
c4f50183 | 34 | EXPORT_SYMBOL_GPL(tracing_on); |
a3583244 SR |
35 | |
36 | /** | |
37 | * tracing_off - turn off all tracing buffers | |
38 | * | |
39 | * This function stops all tracing buffers from recording data. | |
40 | * It does not disable any overhead the tracers themselves may | |
41 | * be causing. This function simply causes all recording to | |
42 | * the ring buffers to fail. | |
43 | */ | |
44 | void tracing_off(void) | |
45 | { | |
46 | ring_buffers_off = 1; | |
47 | } | |
c4f50183 | 48 | EXPORT_SYMBOL_GPL(tracing_off); |
a3583244 | 49 | |
7a8e76a3 SR |
50 | /* Up this if you want to test the TIME_EXTENTS and normalization */ |
51 | #define DEBUG_SHIFT 0 | |
52 | ||
53 | /* FIXME!!! */ | |
54 | u64 ring_buffer_time_stamp(int cpu) | |
55 | { | |
47e74f2b SR |
56 | u64 time; |
57 | ||
58 | preempt_disable_notrace(); | |
7a8e76a3 | 59 | /* shift to debug/test normalization and TIME_EXTENTS */ |
47e74f2b SR |
60 | time = sched_clock() << DEBUG_SHIFT; |
61 | preempt_enable_notrace(); | |
62 | ||
63 | return time; | |
7a8e76a3 | 64 | } |
c4f50183 | 65 | EXPORT_SYMBOL_GPL(ring_buffer_time_stamp); |
7a8e76a3 SR |
66 | |
67 | void ring_buffer_normalize_time_stamp(int cpu, u64 *ts) | |
68 | { | |
69 | /* Just stupid testing the normalize function and deltas */ | |
70 | *ts >>= DEBUG_SHIFT; | |
71 | } | |
c4f50183 | 72 | EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp); |
7a8e76a3 SR |
73 | |
74 | #define RB_EVNT_HDR_SIZE (sizeof(struct ring_buffer_event)) | |
75 | #define RB_ALIGNMENT_SHIFT 2 | |
76 | #define RB_ALIGNMENT (1 << RB_ALIGNMENT_SHIFT) | |
77 | #define RB_MAX_SMALL_DATA 28 | |
78 | ||
79 | enum { | |
80 | RB_LEN_TIME_EXTEND = 8, | |
81 | RB_LEN_TIME_STAMP = 16, | |
82 | }; | |
83 | ||
84 | /* inline for ring buffer fast paths */ | |
85 | static inline unsigned | |
86 | rb_event_length(struct ring_buffer_event *event) | |
87 | { | |
88 | unsigned length; | |
89 | ||
90 | switch (event->type) { | |
91 | case RINGBUF_TYPE_PADDING: | |
92 | /* undefined */ | |
93 | return -1; | |
94 | ||
95 | case RINGBUF_TYPE_TIME_EXTEND: | |
96 | return RB_LEN_TIME_EXTEND; | |
97 | ||
98 | case RINGBUF_TYPE_TIME_STAMP: | |
99 | return RB_LEN_TIME_STAMP; | |
100 | ||
101 | case RINGBUF_TYPE_DATA: | |
102 | if (event->len) | |
103 | length = event->len << RB_ALIGNMENT_SHIFT; | |
104 | else | |
105 | length = event->array[0]; | |
106 | return length + RB_EVNT_HDR_SIZE; | |
107 | default: | |
108 | BUG(); | |
109 | } | |
110 | /* not hit */ | |
111 | return 0; | |
112 | } | |
113 | ||
114 | /** | |
115 | * ring_buffer_event_length - return the length of the event | |
116 | * @event: the event to get the length of | |
117 | */ | |
118 | unsigned ring_buffer_event_length(struct ring_buffer_event *event) | |
119 | { | |
120 | return rb_event_length(event); | |
121 | } | |
c4f50183 | 122 | EXPORT_SYMBOL_GPL(ring_buffer_event_length); |
7a8e76a3 SR |
123 | |
124 | /* inline for ring buffer fast paths */ | |
125 | static inline void * | |
126 | rb_event_data(struct ring_buffer_event *event) | |
127 | { | |
128 | BUG_ON(event->type != RINGBUF_TYPE_DATA); | |
129 | /* If length is in len field, then array[0] has the data */ | |
130 | if (event->len) | |
131 | return (void *)&event->array[0]; | |
132 | /* Otherwise length is in array[0] and array[1] has the data */ | |
133 | return (void *)&event->array[1]; | |
134 | } | |
135 | ||
136 | /** | |
137 | * ring_buffer_event_data - return the data of the event | |
138 | * @event: the event to get the data from | |
139 | */ | |
140 | void *ring_buffer_event_data(struct ring_buffer_event *event) | |
141 | { | |
142 | return rb_event_data(event); | |
143 | } | |
c4f50183 | 144 | EXPORT_SYMBOL_GPL(ring_buffer_event_data); |
7a8e76a3 SR |
145 | |
146 | #define for_each_buffer_cpu(buffer, cpu) \ | |
147 | for_each_cpu_mask(cpu, buffer->cpumask) | |
148 | ||
149 | #define TS_SHIFT 27 | |
150 | #define TS_MASK ((1ULL << TS_SHIFT) - 1) | |
151 | #define TS_DELTA_TEST (~TS_MASK) | |
152 | ||
153 | /* | |
154 | * This hack stolen from mm/slob.c. | |
155 | * We can store per page timing information in the page frame of the page. | |
156 | * Thanks to Peter Zijlstra for suggesting this idea. | |
157 | */ | |
158 | struct buffer_page { | |
e4c2ce82 | 159 | u64 time_stamp; /* page time stamp */ |
bf41a158 SR |
160 | local_t write; /* index for next write */ |
161 | local_t commit; /* write commited index */ | |
6f807acd | 162 | unsigned read; /* index for next read */ |
e4c2ce82 SR |
163 | struct list_head list; /* list of free pages */ |
164 | void *page; /* Actual data page */ | |
7a8e76a3 SR |
165 | }; |
166 | ||
ed56829c SR |
167 | /* |
168 | * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing | |
169 | * this issue out. | |
170 | */ | |
171 | static inline void free_buffer_page(struct buffer_page *bpage) | |
172 | { | |
e4c2ce82 | 173 | if (bpage->page) |
6ae2a076 | 174 | free_page((unsigned long)bpage->page); |
e4c2ce82 | 175 | kfree(bpage); |
ed56829c SR |
176 | } |
177 | ||
7a8e76a3 SR |
178 | /* |
179 | * We need to fit the time_stamp delta into 27 bits. | |
180 | */ | |
181 | static inline int test_time_stamp(u64 delta) | |
182 | { | |
183 | if (delta & TS_DELTA_TEST) | |
184 | return 1; | |
185 | return 0; | |
186 | } | |
187 | ||
188 | #define BUF_PAGE_SIZE PAGE_SIZE | |
189 | ||
190 | /* | |
191 | * head_page == tail_page && head == tail then buffer is empty. | |
192 | */ | |
193 | struct ring_buffer_per_cpu { | |
194 | int cpu; | |
195 | struct ring_buffer *buffer; | |
196 | spinlock_t lock; | |
197 | struct lock_class_key lock_key; | |
198 | struct list_head pages; | |
6f807acd SR |
199 | struct buffer_page *head_page; /* read from head */ |
200 | struct buffer_page *tail_page; /* write to tail */ | |
bf41a158 | 201 | struct buffer_page *commit_page; /* commited pages */ |
d769041f | 202 | struct buffer_page *reader_page; |
7a8e76a3 SR |
203 | unsigned long overrun; |
204 | unsigned long entries; | |
205 | u64 write_stamp; | |
206 | u64 read_stamp; | |
207 | atomic_t record_disabled; | |
208 | }; | |
209 | ||
210 | struct ring_buffer { | |
211 | unsigned long size; | |
212 | unsigned pages; | |
213 | unsigned flags; | |
214 | int cpus; | |
215 | cpumask_t cpumask; | |
216 | atomic_t record_disabled; | |
217 | ||
218 | struct mutex mutex; | |
219 | ||
220 | struct ring_buffer_per_cpu **buffers; | |
221 | }; | |
222 | ||
223 | struct ring_buffer_iter { | |
224 | struct ring_buffer_per_cpu *cpu_buffer; | |
225 | unsigned long head; | |
226 | struct buffer_page *head_page; | |
227 | u64 read_stamp; | |
228 | }; | |
229 | ||
bf41a158 SR |
230 | #define RB_WARN_ON(buffer, cond) \ |
231 | do { \ | |
232 | if (unlikely(cond)) { \ | |
233 | atomic_inc(&buffer->record_disabled); \ | |
234 | WARN_ON(1); \ | |
235 | } \ | |
236 | } while (0) | |
237 | ||
238 | #define RB_WARN_ON_RET(buffer, cond) \ | |
239 | do { \ | |
240 | if (unlikely(cond)) { \ | |
241 | atomic_inc(&buffer->record_disabled); \ | |
242 | WARN_ON(1); \ | |
243 | return -1; \ | |
244 | } \ | |
245 | } while (0) | |
246 | ||
247 | #define RB_WARN_ON_ONCE(buffer, cond) \ | |
248 | do { \ | |
249 | static int once; \ | |
250 | if (unlikely(cond) && !once) { \ | |
251 | once++; \ | |
252 | atomic_inc(&buffer->record_disabled); \ | |
253 | WARN_ON(1); \ | |
254 | } \ | |
255 | } while (0) | |
7a8e76a3 SR |
256 | |
257 | /** | |
258 | * check_pages - integrity check of buffer pages | |
259 | * @cpu_buffer: CPU buffer with pages to test | |
260 | * | |
261 | * As a safty measure we check to make sure the data pages have not | |
262 | * been corrupted. | |
263 | */ | |
264 | static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) | |
265 | { | |
266 | struct list_head *head = &cpu_buffer->pages; | |
267 | struct buffer_page *page, *tmp; | |
268 | ||
bf41a158 SR |
269 | RB_WARN_ON_RET(cpu_buffer, head->next->prev != head); |
270 | RB_WARN_ON_RET(cpu_buffer, head->prev->next != head); | |
7a8e76a3 SR |
271 | |
272 | list_for_each_entry_safe(page, tmp, head, list) { | |
bf41a158 SR |
273 | RB_WARN_ON_RET(cpu_buffer, |
274 | page->list.next->prev != &page->list); | |
275 | RB_WARN_ON_RET(cpu_buffer, | |
276 | page->list.prev->next != &page->list); | |
7a8e76a3 SR |
277 | } |
278 | ||
279 | return 0; | |
280 | } | |
281 | ||
7a8e76a3 SR |
282 | static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, |
283 | unsigned nr_pages) | |
284 | { | |
285 | struct list_head *head = &cpu_buffer->pages; | |
286 | struct buffer_page *page, *tmp; | |
287 | unsigned long addr; | |
288 | LIST_HEAD(pages); | |
289 | unsigned i; | |
290 | ||
291 | for (i = 0; i < nr_pages; i++) { | |
e4c2ce82 | 292 | page = kzalloc_node(ALIGN(sizeof(*page), cache_line_size()), |
aa1e0e3b | 293 | GFP_KERNEL, cpu_to_node(cpu_buffer->cpu)); |
e4c2ce82 SR |
294 | if (!page) |
295 | goto free_pages; | |
296 | list_add(&page->list, &pages); | |
297 | ||
7a8e76a3 SR |
298 | addr = __get_free_page(GFP_KERNEL); |
299 | if (!addr) | |
300 | goto free_pages; | |
e4c2ce82 | 301 | page->page = (void *)addr; |
7a8e76a3 SR |
302 | } |
303 | ||
304 | list_splice(&pages, head); | |
305 | ||
306 | rb_check_pages(cpu_buffer); | |
307 | ||
308 | return 0; | |
309 | ||
310 | free_pages: | |
311 | list_for_each_entry_safe(page, tmp, &pages, list) { | |
312 | list_del_init(&page->list); | |
ed56829c | 313 | free_buffer_page(page); |
7a8e76a3 SR |
314 | } |
315 | return -ENOMEM; | |
316 | } | |
317 | ||
318 | static struct ring_buffer_per_cpu * | |
319 | rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu) | |
320 | { | |
321 | struct ring_buffer_per_cpu *cpu_buffer; | |
e4c2ce82 | 322 | struct buffer_page *page; |
d769041f | 323 | unsigned long addr; |
7a8e76a3 SR |
324 | int ret; |
325 | ||
326 | cpu_buffer = kzalloc_node(ALIGN(sizeof(*cpu_buffer), cache_line_size()), | |
327 | GFP_KERNEL, cpu_to_node(cpu)); | |
328 | if (!cpu_buffer) | |
329 | return NULL; | |
330 | ||
331 | cpu_buffer->cpu = cpu; | |
332 | cpu_buffer->buffer = buffer; | |
333 | spin_lock_init(&cpu_buffer->lock); | |
334 | INIT_LIST_HEAD(&cpu_buffer->pages); | |
335 | ||
e4c2ce82 SR |
336 | page = kzalloc_node(ALIGN(sizeof(*page), cache_line_size()), |
337 | GFP_KERNEL, cpu_to_node(cpu)); | |
338 | if (!page) | |
339 | goto fail_free_buffer; | |
340 | ||
341 | cpu_buffer->reader_page = page; | |
d769041f SR |
342 | addr = __get_free_page(GFP_KERNEL); |
343 | if (!addr) | |
e4c2ce82 SR |
344 | goto fail_free_reader; |
345 | page->page = (void *)addr; | |
346 | ||
d769041f | 347 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); |
d769041f | 348 | |
7a8e76a3 SR |
349 | ret = rb_allocate_pages(cpu_buffer, buffer->pages); |
350 | if (ret < 0) | |
d769041f | 351 | goto fail_free_reader; |
7a8e76a3 SR |
352 | |
353 | cpu_buffer->head_page | |
354 | = list_entry(cpu_buffer->pages.next, struct buffer_page, list); | |
bf41a158 | 355 | cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; |
7a8e76a3 SR |
356 | |
357 | return cpu_buffer; | |
358 | ||
d769041f SR |
359 | fail_free_reader: |
360 | free_buffer_page(cpu_buffer->reader_page); | |
361 | ||
7a8e76a3 SR |
362 | fail_free_buffer: |
363 | kfree(cpu_buffer); | |
364 | return NULL; | |
365 | } | |
366 | ||
367 | static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) | |
368 | { | |
369 | struct list_head *head = &cpu_buffer->pages; | |
370 | struct buffer_page *page, *tmp; | |
371 | ||
d769041f SR |
372 | list_del_init(&cpu_buffer->reader_page->list); |
373 | free_buffer_page(cpu_buffer->reader_page); | |
374 | ||
7a8e76a3 SR |
375 | list_for_each_entry_safe(page, tmp, head, list) { |
376 | list_del_init(&page->list); | |
ed56829c | 377 | free_buffer_page(page); |
7a8e76a3 SR |
378 | } |
379 | kfree(cpu_buffer); | |
380 | } | |
381 | ||
a7b13743 SR |
382 | /* |
383 | * Causes compile errors if the struct buffer_page gets bigger | |
384 | * than the struct page. | |
385 | */ | |
386 | extern int ring_buffer_page_too_big(void); | |
387 | ||
7a8e76a3 SR |
388 | /** |
389 | * ring_buffer_alloc - allocate a new ring_buffer | |
68814b58 | 390 | * @size: the size in bytes per cpu that is needed. |
7a8e76a3 SR |
391 | * @flags: attributes to set for the ring buffer. |
392 | * | |
393 | * Currently the only flag that is available is the RB_FL_OVERWRITE | |
394 | * flag. This flag means that the buffer will overwrite old data | |
395 | * when the buffer wraps. If this flag is not set, the buffer will | |
396 | * drop data when the tail hits the head. | |
397 | */ | |
398 | struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags) | |
399 | { | |
400 | struct ring_buffer *buffer; | |
401 | int bsize; | |
402 | int cpu; | |
403 | ||
a7b13743 SR |
404 | /* Paranoid! Optimizes out when all is well */ |
405 | if (sizeof(struct buffer_page) > sizeof(struct page)) | |
406 | ring_buffer_page_too_big(); | |
407 | ||
408 | ||
7a8e76a3 SR |
409 | /* keep it in its own cache line */ |
410 | buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()), | |
411 | GFP_KERNEL); | |
412 | if (!buffer) | |
413 | return NULL; | |
414 | ||
415 | buffer->pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); | |
416 | buffer->flags = flags; | |
417 | ||
418 | /* need at least two pages */ | |
419 | if (buffer->pages == 1) | |
420 | buffer->pages++; | |
421 | ||
422 | buffer->cpumask = cpu_possible_map; | |
423 | buffer->cpus = nr_cpu_ids; | |
424 | ||
425 | bsize = sizeof(void *) * nr_cpu_ids; | |
426 | buffer->buffers = kzalloc(ALIGN(bsize, cache_line_size()), | |
427 | GFP_KERNEL); | |
428 | if (!buffer->buffers) | |
429 | goto fail_free_buffer; | |
430 | ||
431 | for_each_buffer_cpu(buffer, cpu) { | |
432 | buffer->buffers[cpu] = | |
433 | rb_allocate_cpu_buffer(buffer, cpu); | |
434 | if (!buffer->buffers[cpu]) | |
435 | goto fail_free_buffers; | |
436 | } | |
437 | ||
438 | mutex_init(&buffer->mutex); | |
439 | ||
440 | return buffer; | |
441 | ||
442 | fail_free_buffers: | |
443 | for_each_buffer_cpu(buffer, cpu) { | |
444 | if (buffer->buffers[cpu]) | |
445 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
446 | } | |
447 | kfree(buffer->buffers); | |
448 | ||
449 | fail_free_buffer: | |
450 | kfree(buffer); | |
451 | return NULL; | |
452 | } | |
c4f50183 | 453 | EXPORT_SYMBOL_GPL(ring_buffer_alloc); |
7a8e76a3 SR |
454 | |
455 | /** | |
456 | * ring_buffer_free - free a ring buffer. | |
457 | * @buffer: the buffer to free. | |
458 | */ | |
459 | void | |
460 | ring_buffer_free(struct ring_buffer *buffer) | |
461 | { | |
462 | int cpu; | |
463 | ||
464 | for_each_buffer_cpu(buffer, cpu) | |
465 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
466 | ||
467 | kfree(buffer); | |
468 | } | |
c4f50183 | 469 | EXPORT_SYMBOL_GPL(ring_buffer_free); |
7a8e76a3 SR |
470 | |
471 | static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer); | |
472 | ||
473 | static void | |
474 | rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages) | |
475 | { | |
476 | struct buffer_page *page; | |
477 | struct list_head *p; | |
478 | unsigned i; | |
479 | ||
480 | atomic_inc(&cpu_buffer->record_disabled); | |
481 | synchronize_sched(); | |
482 | ||
483 | for (i = 0; i < nr_pages; i++) { | |
484 | BUG_ON(list_empty(&cpu_buffer->pages)); | |
485 | p = cpu_buffer->pages.next; | |
486 | page = list_entry(p, struct buffer_page, list); | |
487 | list_del_init(&page->list); | |
ed56829c | 488 | free_buffer_page(page); |
7a8e76a3 SR |
489 | } |
490 | BUG_ON(list_empty(&cpu_buffer->pages)); | |
491 | ||
492 | rb_reset_cpu(cpu_buffer); | |
493 | ||
494 | rb_check_pages(cpu_buffer); | |
495 | ||
496 | atomic_dec(&cpu_buffer->record_disabled); | |
497 | ||
498 | } | |
499 | ||
500 | static void | |
501 | rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer, | |
502 | struct list_head *pages, unsigned nr_pages) | |
503 | { | |
504 | struct buffer_page *page; | |
505 | struct list_head *p; | |
506 | unsigned i; | |
507 | ||
508 | atomic_inc(&cpu_buffer->record_disabled); | |
509 | synchronize_sched(); | |
510 | ||
511 | for (i = 0; i < nr_pages; i++) { | |
512 | BUG_ON(list_empty(pages)); | |
513 | p = pages->next; | |
514 | page = list_entry(p, struct buffer_page, list); | |
515 | list_del_init(&page->list); | |
516 | list_add_tail(&page->list, &cpu_buffer->pages); | |
517 | } | |
518 | rb_reset_cpu(cpu_buffer); | |
519 | ||
520 | rb_check_pages(cpu_buffer); | |
521 | ||
522 | atomic_dec(&cpu_buffer->record_disabled); | |
523 | } | |
524 | ||
525 | /** | |
526 | * ring_buffer_resize - resize the ring buffer | |
527 | * @buffer: the buffer to resize. | |
528 | * @size: the new size. | |
529 | * | |
530 | * The tracer is responsible for making sure that the buffer is | |
531 | * not being used while changing the size. | |
532 | * Note: We may be able to change the above requirement by using | |
533 | * RCU synchronizations. | |
534 | * | |
535 | * Minimum size is 2 * BUF_PAGE_SIZE. | |
536 | * | |
537 | * Returns -1 on failure. | |
538 | */ | |
539 | int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size) | |
540 | { | |
541 | struct ring_buffer_per_cpu *cpu_buffer; | |
542 | unsigned nr_pages, rm_pages, new_pages; | |
543 | struct buffer_page *page, *tmp; | |
544 | unsigned long buffer_size; | |
545 | unsigned long addr; | |
546 | LIST_HEAD(pages); | |
547 | int i, cpu; | |
548 | ||
ee51a1de IM |
549 | /* |
550 | * Always succeed at resizing a non-existent buffer: | |
551 | */ | |
552 | if (!buffer) | |
553 | return size; | |
554 | ||
7a8e76a3 SR |
555 | size = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
556 | size *= BUF_PAGE_SIZE; | |
557 | buffer_size = buffer->pages * BUF_PAGE_SIZE; | |
558 | ||
559 | /* we need a minimum of two pages */ | |
560 | if (size < BUF_PAGE_SIZE * 2) | |
561 | size = BUF_PAGE_SIZE * 2; | |
562 | ||
563 | if (size == buffer_size) | |
564 | return size; | |
565 | ||
566 | mutex_lock(&buffer->mutex); | |
567 | ||
568 | nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); | |
569 | ||
570 | if (size < buffer_size) { | |
571 | ||
572 | /* easy case, just free pages */ | |
573 | BUG_ON(nr_pages >= buffer->pages); | |
574 | ||
575 | rm_pages = buffer->pages - nr_pages; | |
576 | ||
577 | for_each_buffer_cpu(buffer, cpu) { | |
578 | cpu_buffer = buffer->buffers[cpu]; | |
579 | rb_remove_pages(cpu_buffer, rm_pages); | |
580 | } | |
581 | goto out; | |
582 | } | |
583 | ||
584 | /* | |
585 | * This is a bit more difficult. We only want to add pages | |
586 | * when we can allocate enough for all CPUs. We do this | |
587 | * by allocating all the pages and storing them on a local | |
588 | * link list. If we succeed in our allocation, then we | |
589 | * add these pages to the cpu_buffers. Otherwise we just free | |
590 | * them all and return -ENOMEM; | |
591 | */ | |
592 | BUG_ON(nr_pages <= buffer->pages); | |
593 | new_pages = nr_pages - buffer->pages; | |
594 | ||
595 | for_each_buffer_cpu(buffer, cpu) { | |
596 | for (i = 0; i < new_pages; i++) { | |
e4c2ce82 SR |
597 | page = kzalloc_node(ALIGN(sizeof(*page), |
598 | cache_line_size()), | |
599 | GFP_KERNEL, cpu_to_node(cpu)); | |
600 | if (!page) | |
601 | goto free_pages; | |
602 | list_add(&page->list, &pages); | |
7a8e76a3 SR |
603 | addr = __get_free_page(GFP_KERNEL); |
604 | if (!addr) | |
605 | goto free_pages; | |
e4c2ce82 | 606 | page->page = (void *)addr; |
7a8e76a3 SR |
607 | } |
608 | } | |
609 | ||
610 | for_each_buffer_cpu(buffer, cpu) { | |
611 | cpu_buffer = buffer->buffers[cpu]; | |
612 | rb_insert_pages(cpu_buffer, &pages, new_pages); | |
613 | } | |
614 | ||
615 | BUG_ON(!list_empty(&pages)); | |
616 | ||
617 | out: | |
618 | buffer->pages = nr_pages; | |
619 | mutex_unlock(&buffer->mutex); | |
620 | ||
621 | return size; | |
622 | ||
623 | free_pages: | |
624 | list_for_each_entry_safe(page, tmp, &pages, list) { | |
625 | list_del_init(&page->list); | |
ed56829c | 626 | free_buffer_page(page); |
7a8e76a3 | 627 | } |
641d2f63 | 628 | mutex_unlock(&buffer->mutex); |
7a8e76a3 SR |
629 | return -ENOMEM; |
630 | } | |
c4f50183 | 631 | EXPORT_SYMBOL_GPL(ring_buffer_resize); |
7a8e76a3 | 632 | |
7a8e76a3 SR |
633 | static inline int rb_null_event(struct ring_buffer_event *event) |
634 | { | |
635 | return event->type == RINGBUF_TYPE_PADDING; | |
636 | } | |
637 | ||
6f807acd | 638 | static inline void *__rb_page_index(struct buffer_page *page, unsigned index) |
7a8e76a3 | 639 | { |
e4c2ce82 | 640 | return page->page + index; |
7a8e76a3 SR |
641 | } |
642 | ||
643 | static inline struct ring_buffer_event * | |
d769041f | 644 | rb_reader_event(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 645 | { |
6f807acd SR |
646 | return __rb_page_index(cpu_buffer->reader_page, |
647 | cpu_buffer->reader_page->read); | |
648 | } | |
649 | ||
650 | static inline struct ring_buffer_event * | |
651 | rb_head_event(struct ring_buffer_per_cpu *cpu_buffer) | |
652 | { | |
653 | return __rb_page_index(cpu_buffer->head_page, | |
654 | cpu_buffer->head_page->read); | |
7a8e76a3 SR |
655 | } |
656 | ||
657 | static inline struct ring_buffer_event * | |
658 | rb_iter_head_event(struct ring_buffer_iter *iter) | |
659 | { | |
6f807acd | 660 | return __rb_page_index(iter->head_page, iter->head); |
7a8e76a3 SR |
661 | } |
662 | ||
bf41a158 SR |
663 | static inline unsigned rb_page_write(struct buffer_page *bpage) |
664 | { | |
665 | return local_read(&bpage->write); | |
666 | } | |
667 | ||
668 | static inline unsigned rb_page_commit(struct buffer_page *bpage) | |
669 | { | |
670 | return local_read(&bpage->commit); | |
671 | } | |
672 | ||
673 | /* Size is determined by what has been commited */ | |
674 | static inline unsigned rb_page_size(struct buffer_page *bpage) | |
675 | { | |
676 | return rb_page_commit(bpage); | |
677 | } | |
678 | ||
679 | static inline unsigned | |
680 | rb_commit_index(struct ring_buffer_per_cpu *cpu_buffer) | |
681 | { | |
682 | return rb_page_commit(cpu_buffer->commit_page); | |
683 | } | |
684 | ||
685 | static inline unsigned rb_head_size(struct ring_buffer_per_cpu *cpu_buffer) | |
686 | { | |
687 | return rb_page_commit(cpu_buffer->head_page); | |
688 | } | |
689 | ||
7a8e76a3 SR |
690 | /* |
691 | * When the tail hits the head and the buffer is in overwrite mode, | |
692 | * the head jumps to the next page and all content on the previous | |
693 | * page is discarded. But before doing so, we update the overrun | |
694 | * variable of the buffer. | |
695 | */ | |
696 | static void rb_update_overflow(struct ring_buffer_per_cpu *cpu_buffer) | |
697 | { | |
698 | struct ring_buffer_event *event; | |
699 | unsigned long head; | |
700 | ||
701 | for (head = 0; head < rb_head_size(cpu_buffer); | |
702 | head += rb_event_length(event)) { | |
703 | ||
6f807acd | 704 | event = __rb_page_index(cpu_buffer->head_page, head); |
7a8e76a3 SR |
705 | BUG_ON(rb_null_event(event)); |
706 | /* Only count data entries */ | |
707 | if (event->type != RINGBUF_TYPE_DATA) | |
708 | continue; | |
709 | cpu_buffer->overrun++; | |
710 | cpu_buffer->entries--; | |
711 | } | |
712 | } | |
713 | ||
714 | static inline void rb_inc_page(struct ring_buffer_per_cpu *cpu_buffer, | |
715 | struct buffer_page **page) | |
716 | { | |
717 | struct list_head *p = (*page)->list.next; | |
718 | ||
719 | if (p == &cpu_buffer->pages) | |
720 | p = p->next; | |
721 | ||
722 | *page = list_entry(p, struct buffer_page, list); | |
723 | } | |
724 | ||
bf41a158 SR |
725 | static inline unsigned |
726 | rb_event_index(struct ring_buffer_event *event) | |
727 | { | |
728 | unsigned long addr = (unsigned long)event; | |
729 | ||
730 | return (addr & ~PAGE_MASK) - (PAGE_SIZE - BUF_PAGE_SIZE); | |
731 | } | |
732 | ||
733 | static inline int | |
734 | rb_is_commit(struct ring_buffer_per_cpu *cpu_buffer, | |
735 | struct ring_buffer_event *event) | |
736 | { | |
737 | unsigned long addr = (unsigned long)event; | |
738 | unsigned long index; | |
739 | ||
740 | index = rb_event_index(event); | |
741 | addr &= PAGE_MASK; | |
742 | ||
743 | return cpu_buffer->commit_page->page == (void *)addr && | |
744 | rb_commit_index(cpu_buffer) == index; | |
745 | } | |
746 | ||
7a8e76a3 | 747 | static inline void |
bf41a158 SR |
748 | rb_set_commit_event(struct ring_buffer_per_cpu *cpu_buffer, |
749 | struct ring_buffer_event *event) | |
7a8e76a3 | 750 | { |
bf41a158 SR |
751 | unsigned long addr = (unsigned long)event; |
752 | unsigned long index; | |
753 | ||
754 | index = rb_event_index(event); | |
755 | addr &= PAGE_MASK; | |
756 | ||
757 | while (cpu_buffer->commit_page->page != (void *)addr) { | |
758 | RB_WARN_ON(cpu_buffer, | |
759 | cpu_buffer->commit_page == cpu_buffer->tail_page); | |
760 | cpu_buffer->commit_page->commit = | |
761 | cpu_buffer->commit_page->write; | |
762 | rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); | |
763 | cpu_buffer->write_stamp = cpu_buffer->commit_page->time_stamp; | |
764 | } | |
765 | ||
766 | /* Now set the commit to the event's index */ | |
767 | local_set(&cpu_buffer->commit_page->commit, index); | |
7a8e76a3 SR |
768 | } |
769 | ||
bf41a158 SR |
770 | static inline void |
771 | rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) | |
7a8e76a3 | 772 | { |
bf41a158 SR |
773 | /* |
774 | * We only race with interrupts and NMIs on this CPU. | |
775 | * If we own the commit event, then we can commit | |
776 | * all others that interrupted us, since the interruptions | |
777 | * are in stack format (they finish before they come | |
778 | * back to us). This allows us to do a simple loop to | |
779 | * assign the commit to the tail. | |
780 | */ | |
781 | while (cpu_buffer->commit_page != cpu_buffer->tail_page) { | |
782 | cpu_buffer->commit_page->commit = | |
783 | cpu_buffer->commit_page->write; | |
784 | rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); | |
785 | cpu_buffer->write_stamp = cpu_buffer->commit_page->time_stamp; | |
786 | /* add barrier to keep gcc from optimizing too much */ | |
787 | barrier(); | |
788 | } | |
789 | while (rb_commit_index(cpu_buffer) != | |
790 | rb_page_write(cpu_buffer->commit_page)) { | |
791 | cpu_buffer->commit_page->commit = | |
792 | cpu_buffer->commit_page->write; | |
793 | barrier(); | |
794 | } | |
7a8e76a3 SR |
795 | } |
796 | ||
d769041f | 797 | static void rb_reset_reader_page(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 798 | { |
d769041f | 799 | cpu_buffer->read_stamp = cpu_buffer->reader_page->time_stamp; |
6f807acd | 800 | cpu_buffer->reader_page->read = 0; |
d769041f SR |
801 | } |
802 | ||
803 | static inline void rb_inc_iter(struct ring_buffer_iter *iter) | |
804 | { | |
805 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
806 | ||
807 | /* | |
808 | * The iterator could be on the reader page (it starts there). | |
809 | * But the head could have moved, since the reader was | |
810 | * found. Check for this case and assign the iterator | |
811 | * to the head page instead of next. | |
812 | */ | |
813 | if (iter->head_page == cpu_buffer->reader_page) | |
814 | iter->head_page = cpu_buffer->head_page; | |
815 | else | |
816 | rb_inc_page(cpu_buffer, &iter->head_page); | |
817 | ||
7a8e76a3 SR |
818 | iter->read_stamp = iter->head_page->time_stamp; |
819 | iter->head = 0; | |
820 | } | |
821 | ||
822 | /** | |
823 | * ring_buffer_update_event - update event type and data | |
824 | * @event: the even to update | |
825 | * @type: the type of event | |
826 | * @length: the size of the event field in the ring buffer | |
827 | * | |
828 | * Update the type and data fields of the event. The length | |
829 | * is the actual size that is written to the ring buffer, | |
830 | * and with this, we can determine what to place into the | |
831 | * data field. | |
832 | */ | |
833 | static inline void | |
834 | rb_update_event(struct ring_buffer_event *event, | |
835 | unsigned type, unsigned length) | |
836 | { | |
837 | event->type = type; | |
838 | ||
839 | switch (type) { | |
840 | ||
841 | case RINGBUF_TYPE_PADDING: | |
842 | break; | |
843 | ||
844 | case RINGBUF_TYPE_TIME_EXTEND: | |
845 | event->len = | |
846 | (RB_LEN_TIME_EXTEND + (RB_ALIGNMENT-1)) | |
847 | >> RB_ALIGNMENT_SHIFT; | |
848 | break; | |
849 | ||
850 | case RINGBUF_TYPE_TIME_STAMP: | |
851 | event->len = | |
852 | (RB_LEN_TIME_STAMP + (RB_ALIGNMENT-1)) | |
853 | >> RB_ALIGNMENT_SHIFT; | |
854 | break; | |
855 | ||
856 | case RINGBUF_TYPE_DATA: | |
857 | length -= RB_EVNT_HDR_SIZE; | |
858 | if (length > RB_MAX_SMALL_DATA) { | |
859 | event->len = 0; | |
860 | event->array[0] = length; | |
861 | } else | |
862 | event->len = | |
863 | (length + (RB_ALIGNMENT-1)) | |
864 | >> RB_ALIGNMENT_SHIFT; | |
865 | break; | |
866 | default: | |
867 | BUG(); | |
868 | } | |
869 | } | |
870 | ||
871 | static inline unsigned rb_calculate_event_length(unsigned length) | |
872 | { | |
873 | struct ring_buffer_event event; /* Used only for sizeof array */ | |
874 | ||
875 | /* zero length can cause confusions */ | |
876 | if (!length) | |
877 | length = 1; | |
878 | ||
879 | if (length > RB_MAX_SMALL_DATA) | |
880 | length += sizeof(event.array[0]); | |
881 | ||
882 | length += RB_EVNT_HDR_SIZE; | |
883 | length = ALIGN(length, RB_ALIGNMENT); | |
884 | ||
885 | return length; | |
886 | } | |
887 | ||
888 | static struct ring_buffer_event * | |
889 | __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, | |
890 | unsigned type, unsigned long length, u64 *ts) | |
891 | { | |
d769041f | 892 | struct buffer_page *tail_page, *head_page, *reader_page; |
bf41a158 | 893 | unsigned long tail, write; |
7a8e76a3 SR |
894 | struct ring_buffer *buffer = cpu_buffer->buffer; |
895 | struct ring_buffer_event *event; | |
bf41a158 | 896 | unsigned long flags; |
7a8e76a3 SR |
897 | |
898 | tail_page = cpu_buffer->tail_page; | |
bf41a158 SR |
899 | write = local_add_return(length, &tail_page->write); |
900 | tail = write - length; | |
7a8e76a3 | 901 | |
bf41a158 SR |
902 | /* See if we shot pass the end of this buffer page */ |
903 | if (write > BUF_PAGE_SIZE) { | |
7a8e76a3 SR |
904 | struct buffer_page *next_page = tail_page; |
905 | ||
bf41a158 SR |
906 | spin_lock_irqsave(&cpu_buffer->lock, flags); |
907 | ||
7a8e76a3 SR |
908 | rb_inc_page(cpu_buffer, &next_page); |
909 | ||
d769041f SR |
910 | head_page = cpu_buffer->head_page; |
911 | reader_page = cpu_buffer->reader_page; | |
912 | ||
913 | /* we grabbed the lock before incrementing */ | |
bf41a158 SR |
914 | RB_WARN_ON(cpu_buffer, next_page == reader_page); |
915 | ||
916 | /* | |
917 | * If for some reason, we had an interrupt storm that made | |
918 | * it all the way around the buffer, bail, and warn | |
919 | * about it. | |
920 | */ | |
921 | if (unlikely(next_page == cpu_buffer->commit_page)) { | |
922 | WARN_ON_ONCE(1); | |
923 | goto out_unlock; | |
924 | } | |
d769041f | 925 | |
7a8e76a3 | 926 | if (next_page == head_page) { |
d769041f | 927 | if (!(buffer->flags & RB_FL_OVERWRITE)) { |
bf41a158 SR |
928 | /* reset write */ |
929 | if (tail <= BUF_PAGE_SIZE) | |
930 | local_set(&tail_page->write, tail); | |
931 | goto out_unlock; | |
d769041f | 932 | } |
7a8e76a3 | 933 | |
bf41a158 SR |
934 | /* tail_page has not moved yet? */ |
935 | if (tail_page == cpu_buffer->tail_page) { | |
936 | /* count overflows */ | |
937 | rb_update_overflow(cpu_buffer); | |
938 | ||
939 | rb_inc_page(cpu_buffer, &head_page); | |
940 | cpu_buffer->head_page = head_page; | |
941 | cpu_buffer->head_page->read = 0; | |
942 | } | |
943 | } | |
7a8e76a3 | 944 | |
bf41a158 SR |
945 | /* |
946 | * If the tail page is still the same as what we think | |
947 | * it is, then it is up to us to update the tail | |
948 | * pointer. | |
949 | */ | |
950 | if (tail_page == cpu_buffer->tail_page) { | |
951 | local_set(&next_page->write, 0); | |
952 | local_set(&next_page->commit, 0); | |
953 | cpu_buffer->tail_page = next_page; | |
954 | ||
955 | /* reread the time stamp */ | |
956 | *ts = ring_buffer_time_stamp(cpu_buffer->cpu); | |
957 | cpu_buffer->tail_page->time_stamp = *ts; | |
7a8e76a3 SR |
958 | } |
959 | ||
bf41a158 SR |
960 | /* |
961 | * The actual tail page has moved forward. | |
962 | */ | |
963 | if (tail < BUF_PAGE_SIZE) { | |
964 | /* Mark the rest of the page with padding */ | |
6f807acd | 965 | event = __rb_page_index(tail_page, tail); |
7a8e76a3 SR |
966 | event->type = RINGBUF_TYPE_PADDING; |
967 | } | |
968 | ||
bf41a158 SR |
969 | if (tail <= BUF_PAGE_SIZE) |
970 | /* Set the write back to the previous setting */ | |
971 | local_set(&tail_page->write, tail); | |
972 | ||
973 | /* | |
974 | * If this was a commit entry that failed, | |
975 | * increment that too | |
976 | */ | |
977 | if (tail_page == cpu_buffer->commit_page && | |
978 | tail == rb_commit_index(cpu_buffer)) { | |
979 | rb_set_commit_to_write(cpu_buffer); | |
980 | } | |
981 | ||
982 | spin_unlock_irqrestore(&cpu_buffer->lock, flags); | |
983 | ||
984 | /* fail and let the caller try again */ | |
985 | return ERR_PTR(-EAGAIN); | |
7a8e76a3 SR |
986 | } |
987 | ||
bf41a158 SR |
988 | /* We reserved something on the buffer */ |
989 | ||
990 | BUG_ON(write > BUF_PAGE_SIZE); | |
7a8e76a3 | 991 | |
6f807acd | 992 | event = __rb_page_index(tail_page, tail); |
7a8e76a3 SR |
993 | rb_update_event(event, type, length); |
994 | ||
bf41a158 SR |
995 | /* |
996 | * If this is a commit and the tail is zero, then update | |
997 | * this page's time stamp. | |
998 | */ | |
999 | if (!tail && rb_is_commit(cpu_buffer, event)) | |
1000 | cpu_buffer->commit_page->time_stamp = *ts; | |
1001 | ||
7a8e76a3 | 1002 | return event; |
bf41a158 SR |
1003 | |
1004 | out_unlock: | |
1005 | spin_unlock_irqrestore(&cpu_buffer->lock, flags); | |
1006 | return NULL; | |
7a8e76a3 SR |
1007 | } |
1008 | ||
1009 | static int | |
1010 | rb_add_time_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
1011 | u64 *ts, u64 *delta) | |
1012 | { | |
1013 | struct ring_buffer_event *event; | |
1014 | static int once; | |
bf41a158 | 1015 | int ret; |
7a8e76a3 SR |
1016 | |
1017 | if (unlikely(*delta > (1ULL << 59) && !once++)) { | |
1018 | printk(KERN_WARNING "Delta way too big! %llu" | |
1019 | " ts=%llu write stamp = %llu\n", | |
e2862c94 SR |
1020 | (unsigned long long)*delta, |
1021 | (unsigned long long)*ts, | |
1022 | (unsigned long long)cpu_buffer->write_stamp); | |
7a8e76a3 SR |
1023 | WARN_ON(1); |
1024 | } | |
1025 | ||
1026 | /* | |
1027 | * The delta is too big, we to add a | |
1028 | * new timestamp. | |
1029 | */ | |
1030 | event = __rb_reserve_next(cpu_buffer, | |
1031 | RINGBUF_TYPE_TIME_EXTEND, | |
1032 | RB_LEN_TIME_EXTEND, | |
1033 | ts); | |
1034 | if (!event) | |
bf41a158 | 1035 | return -EBUSY; |
7a8e76a3 | 1036 | |
bf41a158 SR |
1037 | if (PTR_ERR(event) == -EAGAIN) |
1038 | return -EAGAIN; | |
1039 | ||
1040 | /* Only a commited time event can update the write stamp */ | |
1041 | if (rb_is_commit(cpu_buffer, event)) { | |
1042 | /* | |
1043 | * If this is the first on the page, then we need to | |
1044 | * update the page itself, and just put in a zero. | |
1045 | */ | |
1046 | if (rb_event_index(event)) { | |
1047 | event->time_delta = *delta & TS_MASK; | |
1048 | event->array[0] = *delta >> TS_SHIFT; | |
1049 | } else { | |
1050 | cpu_buffer->commit_page->time_stamp = *ts; | |
1051 | event->time_delta = 0; | |
1052 | event->array[0] = 0; | |
1053 | } | |
7a8e76a3 | 1054 | cpu_buffer->write_stamp = *ts; |
bf41a158 SR |
1055 | /* let the caller know this was the commit */ |
1056 | ret = 1; | |
1057 | } else { | |
1058 | /* Darn, this is just wasted space */ | |
1059 | event->time_delta = 0; | |
1060 | event->array[0] = 0; | |
1061 | ret = 0; | |
7a8e76a3 SR |
1062 | } |
1063 | ||
bf41a158 SR |
1064 | *delta = 0; |
1065 | ||
1066 | return ret; | |
7a8e76a3 SR |
1067 | } |
1068 | ||
1069 | static struct ring_buffer_event * | |
1070 | rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer, | |
1071 | unsigned type, unsigned long length) | |
1072 | { | |
1073 | struct ring_buffer_event *event; | |
1074 | u64 ts, delta; | |
bf41a158 | 1075 | int commit = 0; |
818e3dd3 | 1076 | int nr_loops = 0; |
7a8e76a3 | 1077 | |
bf41a158 | 1078 | again: |
818e3dd3 SR |
1079 | /* |
1080 | * We allow for interrupts to reenter here and do a trace. | |
1081 | * If one does, it will cause this original code to loop | |
1082 | * back here. Even with heavy interrupts happening, this | |
1083 | * should only happen a few times in a row. If this happens | |
1084 | * 1000 times in a row, there must be either an interrupt | |
1085 | * storm or we have something buggy. | |
1086 | * Bail! | |
1087 | */ | |
1088 | if (unlikely(++nr_loops > 1000)) { | |
1089 | RB_WARN_ON(cpu_buffer, 1); | |
1090 | return NULL; | |
1091 | } | |
1092 | ||
7a8e76a3 SR |
1093 | ts = ring_buffer_time_stamp(cpu_buffer->cpu); |
1094 | ||
bf41a158 SR |
1095 | /* |
1096 | * Only the first commit can update the timestamp. | |
1097 | * Yes there is a race here. If an interrupt comes in | |
1098 | * just after the conditional and it traces too, then it | |
1099 | * will also check the deltas. More than one timestamp may | |
1100 | * also be made. But only the entry that did the actual | |
1101 | * commit will be something other than zero. | |
1102 | */ | |
1103 | if (cpu_buffer->tail_page == cpu_buffer->commit_page && | |
1104 | rb_page_write(cpu_buffer->tail_page) == | |
1105 | rb_commit_index(cpu_buffer)) { | |
1106 | ||
7a8e76a3 SR |
1107 | delta = ts - cpu_buffer->write_stamp; |
1108 | ||
bf41a158 SR |
1109 | /* make sure this delta is calculated here */ |
1110 | barrier(); | |
1111 | ||
1112 | /* Did the write stamp get updated already? */ | |
1113 | if (unlikely(ts < cpu_buffer->write_stamp)) | |
4143c5cb | 1114 | delta = 0; |
bf41a158 | 1115 | |
7a8e76a3 | 1116 | if (test_time_stamp(delta)) { |
7a8e76a3 | 1117 | |
bf41a158 SR |
1118 | commit = rb_add_time_stamp(cpu_buffer, &ts, &delta); |
1119 | ||
1120 | if (commit == -EBUSY) | |
7a8e76a3 | 1121 | return NULL; |
bf41a158 SR |
1122 | |
1123 | if (commit == -EAGAIN) | |
1124 | goto again; | |
1125 | ||
1126 | RB_WARN_ON(cpu_buffer, commit < 0); | |
7a8e76a3 | 1127 | } |
bf41a158 SR |
1128 | } else |
1129 | /* Non commits have zero deltas */ | |
7a8e76a3 | 1130 | delta = 0; |
7a8e76a3 SR |
1131 | |
1132 | event = __rb_reserve_next(cpu_buffer, type, length, &ts); | |
bf41a158 SR |
1133 | if (PTR_ERR(event) == -EAGAIN) |
1134 | goto again; | |
1135 | ||
1136 | if (!event) { | |
1137 | if (unlikely(commit)) | |
1138 | /* | |
1139 | * Ouch! We needed a timestamp and it was commited. But | |
1140 | * we didn't get our event reserved. | |
1141 | */ | |
1142 | rb_set_commit_to_write(cpu_buffer); | |
7a8e76a3 | 1143 | return NULL; |
bf41a158 | 1144 | } |
7a8e76a3 | 1145 | |
bf41a158 SR |
1146 | /* |
1147 | * If the timestamp was commited, make the commit our entry | |
1148 | * now so that we will update it when needed. | |
1149 | */ | |
1150 | if (commit) | |
1151 | rb_set_commit_event(cpu_buffer, event); | |
1152 | else if (!rb_is_commit(cpu_buffer, event)) | |
7a8e76a3 SR |
1153 | delta = 0; |
1154 | ||
1155 | event->time_delta = delta; | |
1156 | ||
1157 | return event; | |
1158 | } | |
1159 | ||
bf41a158 SR |
1160 | static DEFINE_PER_CPU(int, rb_need_resched); |
1161 | ||
7a8e76a3 SR |
1162 | /** |
1163 | * ring_buffer_lock_reserve - reserve a part of the buffer | |
1164 | * @buffer: the ring buffer to reserve from | |
1165 | * @length: the length of the data to reserve (excluding event header) | |
1166 | * @flags: a pointer to save the interrupt flags | |
1167 | * | |
1168 | * Returns a reseverd event on the ring buffer to copy directly to. | |
1169 | * The user of this interface will need to get the body to write into | |
1170 | * and can use the ring_buffer_event_data() interface. | |
1171 | * | |
1172 | * The length is the length of the data needed, not the event length | |
1173 | * which also includes the event header. | |
1174 | * | |
1175 | * Must be paired with ring_buffer_unlock_commit, unless NULL is returned. | |
1176 | * If NULL is returned, then nothing has been allocated or locked. | |
1177 | */ | |
1178 | struct ring_buffer_event * | |
1179 | ring_buffer_lock_reserve(struct ring_buffer *buffer, | |
1180 | unsigned long length, | |
1181 | unsigned long *flags) | |
1182 | { | |
1183 | struct ring_buffer_per_cpu *cpu_buffer; | |
1184 | struct ring_buffer_event *event; | |
bf41a158 | 1185 | int cpu, resched; |
7a8e76a3 | 1186 | |
a3583244 SR |
1187 | if (ring_buffers_off) |
1188 | return NULL; | |
1189 | ||
7a8e76a3 SR |
1190 | if (atomic_read(&buffer->record_disabled)) |
1191 | return NULL; | |
1192 | ||
bf41a158 SR |
1193 | /* If we are tracing schedule, we don't want to recurse */ |
1194 | resched = need_resched(); | |
1195 | preempt_disable_notrace(); | |
1196 | ||
7a8e76a3 SR |
1197 | cpu = raw_smp_processor_id(); |
1198 | ||
1199 | if (!cpu_isset(cpu, buffer->cpumask)) | |
d769041f | 1200 | goto out; |
7a8e76a3 SR |
1201 | |
1202 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 SR |
1203 | |
1204 | if (atomic_read(&cpu_buffer->record_disabled)) | |
d769041f | 1205 | goto out; |
7a8e76a3 SR |
1206 | |
1207 | length = rb_calculate_event_length(length); | |
1208 | if (length > BUF_PAGE_SIZE) | |
bf41a158 | 1209 | goto out; |
7a8e76a3 SR |
1210 | |
1211 | event = rb_reserve_next_event(cpu_buffer, RINGBUF_TYPE_DATA, length); | |
1212 | if (!event) | |
d769041f | 1213 | goto out; |
7a8e76a3 | 1214 | |
bf41a158 SR |
1215 | /* |
1216 | * Need to store resched state on this cpu. | |
1217 | * Only the first needs to. | |
1218 | */ | |
1219 | ||
1220 | if (preempt_count() == 1) | |
1221 | per_cpu(rb_need_resched, cpu) = resched; | |
1222 | ||
7a8e76a3 SR |
1223 | return event; |
1224 | ||
d769041f | 1225 | out: |
bf41a158 | 1226 | if (resched) |
4f5a7f40 | 1227 | preempt_enable_no_resched_notrace(); |
bf41a158 SR |
1228 | else |
1229 | preempt_enable_notrace(); | |
7a8e76a3 SR |
1230 | return NULL; |
1231 | } | |
c4f50183 | 1232 | EXPORT_SYMBOL_GPL(ring_buffer_lock_reserve); |
7a8e76a3 SR |
1233 | |
1234 | static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, | |
1235 | struct ring_buffer_event *event) | |
1236 | { | |
7a8e76a3 | 1237 | cpu_buffer->entries++; |
bf41a158 SR |
1238 | |
1239 | /* Only process further if we own the commit */ | |
1240 | if (!rb_is_commit(cpu_buffer, event)) | |
1241 | return; | |
1242 | ||
1243 | cpu_buffer->write_stamp += event->time_delta; | |
1244 | ||
1245 | rb_set_commit_to_write(cpu_buffer); | |
7a8e76a3 SR |
1246 | } |
1247 | ||
1248 | /** | |
1249 | * ring_buffer_unlock_commit - commit a reserved | |
1250 | * @buffer: The buffer to commit to | |
1251 | * @event: The event pointer to commit. | |
1252 | * @flags: the interrupt flags received from ring_buffer_lock_reserve. | |
1253 | * | |
1254 | * This commits the data to the ring buffer, and releases any locks held. | |
1255 | * | |
1256 | * Must be paired with ring_buffer_lock_reserve. | |
1257 | */ | |
1258 | int ring_buffer_unlock_commit(struct ring_buffer *buffer, | |
1259 | struct ring_buffer_event *event, | |
1260 | unsigned long flags) | |
1261 | { | |
1262 | struct ring_buffer_per_cpu *cpu_buffer; | |
1263 | int cpu = raw_smp_processor_id(); | |
1264 | ||
1265 | cpu_buffer = buffer->buffers[cpu]; | |
1266 | ||
7a8e76a3 SR |
1267 | rb_commit(cpu_buffer, event); |
1268 | ||
bf41a158 SR |
1269 | /* |
1270 | * Only the last preempt count needs to restore preemption. | |
1271 | */ | |
1272 | if (preempt_count() == 1) { | |
1273 | if (per_cpu(rb_need_resched, cpu)) | |
1274 | preempt_enable_no_resched_notrace(); | |
1275 | else | |
1276 | preempt_enable_notrace(); | |
1277 | } else | |
1278 | preempt_enable_no_resched_notrace(); | |
7a8e76a3 SR |
1279 | |
1280 | return 0; | |
1281 | } | |
c4f50183 | 1282 | EXPORT_SYMBOL_GPL(ring_buffer_unlock_commit); |
7a8e76a3 SR |
1283 | |
1284 | /** | |
1285 | * ring_buffer_write - write data to the buffer without reserving | |
1286 | * @buffer: The ring buffer to write to. | |
1287 | * @length: The length of the data being written (excluding the event header) | |
1288 | * @data: The data to write to the buffer. | |
1289 | * | |
1290 | * This is like ring_buffer_lock_reserve and ring_buffer_unlock_commit as | |
1291 | * one function. If you already have the data to write to the buffer, it | |
1292 | * may be easier to simply call this function. | |
1293 | * | |
1294 | * Note, like ring_buffer_lock_reserve, the length is the length of the data | |
1295 | * and not the length of the event which would hold the header. | |
1296 | */ | |
1297 | int ring_buffer_write(struct ring_buffer *buffer, | |
1298 | unsigned long length, | |
1299 | void *data) | |
1300 | { | |
1301 | struct ring_buffer_per_cpu *cpu_buffer; | |
1302 | struct ring_buffer_event *event; | |
bf41a158 | 1303 | unsigned long event_length; |
7a8e76a3 SR |
1304 | void *body; |
1305 | int ret = -EBUSY; | |
bf41a158 | 1306 | int cpu, resched; |
7a8e76a3 | 1307 | |
a3583244 SR |
1308 | if (ring_buffers_off) |
1309 | return -EBUSY; | |
1310 | ||
7a8e76a3 SR |
1311 | if (atomic_read(&buffer->record_disabled)) |
1312 | return -EBUSY; | |
1313 | ||
bf41a158 SR |
1314 | resched = need_resched(); |
1315 | preempt_disable_notrace(); | |
1316 | ||
7a8e76a3 SR |
1317 | cpu = raw_smp_processor_id(); |
1318 | ||
1319 | if (!cpu_isset(cpu, buffer->cpumask)) | |
d769041f | 1320 | goto out; |
7a8e76a3 SR |
1321 | |
1322 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 SR |
1323 | |
1324 | if (atomic_read(&cpu_buffer->record_disabled)) | |
1325 | goto out; | |
1326 | ||
1327 | event_length = rb_calculate_event_length(length); | |
1328 | event = rb_reserve_next_event(cpu_buffer, | |
1329 | RINGBUF_TYPE_DATA, event_length); | |
1330 | if (!event) | |
1331 | goto out; | |
1332 | ||
1333 | body = rb_event_data(event); | |
1334 | ||
1335 | memcpy(body, data, length); | |
1336 | ||
1337 | rb_commit(cpu_buffer, event); | |
1338 | ||
1339 | ret = 0; | |
1340 | out: | |
bf41a158 SR |
1341 | if (resched) |
1342 | preempt_enable_no_resched_notrace(); | |
1343 | else | |
1344 | preempt_enable_notrace(); | |
7a8e76a3 SR |
1345 | |
1346 | return ret; | |
1347 | } | |
c4f50183 | 1348 | EXPORT_SYMBOL_GPL(ring_buffer_write); |
7a8e76a3 | 1349 | |
bf41a158 SR |
1350 | static inline int rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) |
1351 | { | |
1352 | struct buffer_page *reader = cpu_buffer->reader_page; | |
1353 | struct buffer_page *head = cpu_buffer->head_page; | |
1354 | struct buffer_page *commit = cpu_buffer->commit_page; | |
1355 | ||
1356 | return reader->read == rb_page_commit(reader) && | |
1357 | (commit == reader || | |
1358 | (commit == head && | |
1359 | head->read == rb_page_commit(commit))); | |
1360 | } | |
1361 | ||
7a8e76a3 SR |
1362 | /** |
1363 | * ring_buffer_record_disable - stop all writes into the buffer | |
1364 | * @buffer: The ring buffer to stop writes to. | |
1365 | * | |
1366 | * This prevents all writes to the buffer. Any attempt to write | |
1367 | * to the buffer after this will fail and return NULL. | |
1368 | * | |
1369 | * The caller should call synchronize_sched() after this. | |
1370 | */ | |
1371 | void ring_buffer_record_disable(struct ring_buffer *buffer) | |
1372 | { | |
1373 | atomic_inc(&buffer->record_disabled); | |
1374 | } | |
c4f50183 | 1375 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable); |
7a8e76a3 SR |
1376 | |
1377 | /** | |
1378 | * ring_buffer_record_enable - enable writes to the buffer | |
1379 | * @buffer: The ring buffer to enable writes | |
1380 | * | |
1381 | * Note, multiple disables will need the same number of enables | |
1382 | * to truely enable the writing (much like preempt_disable). | |
1383 | */ | |
1384 | void ring_buffer_record_enable(struct ring_buffer *buffer) | |
1385 | { | |
1386 | atomic_dec(&buffer->record_disabled); | |
1387 | } | |
c4f50183 | 1388 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable); |
7a8e76a3 SR |
1389 | |
1390 | /** | |
1391 | * ring_buffer_record_disable_cpu - stop all writes into the cpu_buffer | |
1392 | * @buffer: The ring buffer to stop writes to. | |
1393 | * @cpu: The CPU buffer to stop | |
1394 | * | |
1395 | * This prevents all writes to the buffer. Any attempt to write | |
1396 | * to the buffer after this will fail and return NULL. | |
1397 | * | |
1398 | * The caller should call synchronize_sched() after this. | |
1399 | */ | |
1400 | void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu) | |
1401 | { | |
1402 | struct ring_buffer_per_cpu *cpu_buffer; | |
1403 | ||
1404 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1405 | return; | |
1406 | ||
1407 | cpu_buffer = buffer->buffers[cpu]; | |
1408 | atomic_inc(&cpu_buffer->record_disabled); | |
1409 | } | |
c4f50183 | 1410 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable_cpu); |
7a8e76a3 SR |
1411 | |
1412 | /** | |
1413 | * ring_buffer_record_enable_cpu - enable writes to the buffer | |
1414 | * @buffer: The ring buffer to enable writes | |
1415 | * @cpu: The CPU to enable. | |
1416 | * | |
1417 | * Note, multiple disables will need the same number of enables | |
1418 | * to truely enable the writing (much like preempt_disable). | |
1419 | */ | |
1420 | void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu) | |
1421 | { | |
1422 | struct ring_buffer_per_cpu *cpu_buffer; | |
1423 | ||
1424 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1425 | return; | |
1426 | ||
1427 | cpu_buffer = buffer->buffers[cpu]; | |
1428 | atomic_dec(&cpu_buffer->record_disabled); | |
1429 | } | |
c4f50183 | 1430 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu); |
7a8e76a3 SR |
1431 | |
1432 | /** | |
1433 | * ring_buffer_entries_cpu - get the number of entries in a cpu buffer | |
1434 | * @buffer: The ring buffer | |
1435 | * @cpu: The per CPU buffer to get the entries from. | |
1436 | */ | |
1437 | unsigned long ring_buffer_entries_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->entries; | |
1446 | } | |
c4f50183 | 1447 | EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu); |
7a8e76a3 SR |
1448 | |
1449 | /** | |
1450 | * ring_buffer_overrun_cpu - get the number of overruns in a cpu_buffer | |
1451 | * @buffer: The ring buffer | |
1452 | * @cpu: The per CPU buffer to get the number of overruns from | |
1453 | */ | |
1454 | unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu) | |
1455 | { | |
1456 | struct ring_buffer_per_cpu *cpu_buffer; | |
1457 | ||
1458 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1459 | return 0; | |
1460 | ||
1461 | cpu_buffer = buffer->buffers[cpu]; | |
1462 | return cpu_buffer->overrun; | |
1463 | } | |
c4f50183 | 1464 | EXPORT_SYMBOL_GPL(ring_buffer_overrun_cpu); |
7a8e76a3 SR |
1465 | |
1466 | /** | |
1467 | * ring_buffer_entries - get the number of entries in a buffer | |
1468 | * @buffer: The ring buffer | |
1469 | * | |
1470 | * Returns the total number of entries in the ring buffer | |
1471 | * (all CPU entries) | |
1472 | */ | |
1473 | unsigned long ring_buffer_entries(struct ring_buffer *buffer) | |
1474 | { | |
1475 | struct ring_buffer_per_cpu *cpu_buffer; | |
1476 | unsigned long entries = 0; | |
1477 | int cpu; | |
1478 | ||
1479 | /* if you care about this being correct, lock the buffer */ | |
1480 | for_each_buffer_cpu(buffer, cpu) { | |
1481 | cpu_buffer = buffer->buffers[cpu]; | |
1482 | entries += cpu_buffer->entries; | |
1483 | } | |
1484 | ||
1485 | return entries; | |
1486 | } | |
c4f50183 | 1487 | EXPORT_SYMBOL_GPL(ring_buffer_entries); |
7a8e76a3 SR |
1488 | |
1489 | /** | |
1490 | * ring_buffer_overrun_cpu - get the number of overruns in buffer | |
1491 | * @buffer: The ring buffer | |
1492 | * | |
1493 | * Returns the total number of overruns in the ring buffer | |
1494 | * (all CPU entries) | |
1495 | */ | |
1496 | unsigned long ring_buffer_overruns(struct ring_buffer *buffer) | |
1497 | { | |
1498 | struct ring_buffer_per_cpu *cpu_buffer; | |
1499 | unsigned long overruns = 0; | |
1500 | int cpu; | |
1501 | ||
1502 | /* if you care about this being correct, lock the buffer */ | |
1503 | for_each_buffer_cpu(buffer, cpu) { | |
1504 | cpu_buffer = buffer->buffers[cpu]; | |
1505 | overruns += cpu_buffer->overrun; | |
1506 | } | |
1507 | ||
1508 | return overruns; | |
1509 | } | |
c4f50183 | 1510 | EXPORT_SYMBOL_GPL(ring_buffer_overruns); |
7a8e76a3 SR |
1511 | |
1512 | /** | |
1513 | * ring_buffer_iter_reset - reset an iterator | |
1514 | * @iter: The iterator to reset | |
1515 | * | |
1516 | * Resets the iterator, so that it will start from the beginning | |
1517 | * again. | |
1518 | */ | |
1519 | void ring_buffer_iter_reset(struct ring_buffer_iter *iter) | |
1520 | { | |
1521 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
1522 | ||
d769041f SR |
1523 | /* Iterator usage is expected to have record disabled */ |
1524 | if (list_empty(&cpu_buffer->reader_page->list)) { | |
1525 | iter->head_page = cpu_buffer->head_page; | |
6f807acd | 1526 | iter->head = cpu_buffer->head_page->read; |
d769041f SR |
1527 | } else { |
1528 | iter->head_page = cpu_buffer->reader_page; | |
6f807acd | 1529 | iter->head = cpu_buffer->reader_page->read; |
d769041f SR |
1530 | } |
1531 | if (iter->head) | |
1532 | iter->read_stamp = cpu_buffer->read_stamp; | |
1533 | else | |
1534 | iter->read_stamp = iter->head_page->time_stamp; | |
7a8e76a3 | 1535 | } |
c4f50183 | 1536 | EXPORT_SYMBOL_GPL(ring_buffer_iter_reset); |
7a8e76a3 SR |
1537 | |
1538 | /** | |
1539 | * ring_buffer_iter_empty - check if an iterator has no more to read | |
1540 | * @iter: The iterator to check | |
1541 | */ | |
1542 | int ring_buffer_iter_empty(struct ring_buffer_iter *iter) | |
1543 | { | |
1544 | struct ring_buffer_per_cpu *cpu_buffer; | |
1545 | ||
1546 | cpu_buffer = iter->cpu_buffer; | |
1547 | ||
bf41a158 SR |
1548 | return iter->head_page == cpu_buffer->commit_page && |
1549 | iter->head == rb_commit_index(cpu_buffer); | |
7a8e76a3 | 1550 | } |
c4f50183 | 1551 | EXPORT_SYMBOL_GPL(ring_buffer_iter_empty); |
7a8e76a3 SR |
1552 | |
1553 | static void | |
1554 | rb_update_read_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
1555 | struct ring_buffer_event *event) | |
1556 | { | |
1557 | u64 delta; | |
1558 | ||
1559 | switch (event->type) { | |
1560 | case RINGBUF_TYPE_PADDING: | |
1561 | return; | |
1562 | ||
1563 | case RINGBUF_TYPE_TIME_EXTEND: | |
1564 | delta = event->array[0]; | |
1565 | delta <<= TS_SHIFT; | |
1566 | delta += event->time_delta; | |
1567 | cpu_buffer->read_stamp += delta; | |
1568 | return; | |
1569 | ||
1570 | case RINGBUF_TYPE_TIME_STAMP: | |
1571 | /* FIXME: not implemented */ | |
1572 | return; | |
1573 | ||
1574 | case RINGBUF_TYPE_DATA: | |
1575 | cpu_buffer->read_stamp += event->time_delta; | |
1576 | return; | |
1577 | ||
1578 | default: | |
1579 | BUG(); | |
1580 | } | |
1581 | return; | |
1582 | } | |
1583 | ||
1584 | static void | |
1585 | rb_update_iter_read_stamp(struct ring_buffer_iter *iter, | |
1586 | struct ring_buffer_event *event) | |
1587 | { | |
1588 | u64 delta; | |
1589 | ||
1590 | switch (event->type) { | |
1591 | case RINGBUF_TYPE_PADDING: | |
1592 | return; | |
1593 | ||
1594 | case RINGBUF_TYPE_TIME_EXTEND: | |
1595 | delta = event->array[0]; | |
1596 | delta <<= TS_SHIFT; | |
1597 | delta += event->time_delta; | |
1598 | iter->read_stamp += delta; | |
1599 | return; | |
1600 | ||
1601 | case RINGBUF_TYPE_TIME_STAMP: | |
1602 | /* FIXME: not implemented */ | |
1603 | return; | |
1604 | ||
1605 | case RINGBUF_TYPE_DATA: | |
1606 | iter->read_stamp += event->time_delta; | |
1607 | return; | |
1608 | ||
1609 | default: | |
1610 | BUG(); | |
1611 | } | |
1612 | return; | |
1613 | } | |
1614 | ||
d769041f SR |
1615 | static struct buffer_page * |
1616 | rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) | |
7a8e76a3 | 1617 | { |
d769041f SR |
1618 | struct buffer_page *reader = NULL; |
1619 | unsigned long flags; | |
818e3dd3 | 1620 | int nr_loops = 0; |
d769041f SR |
1621 | |
1622 | spin_lock_irqsave(&cpu_buffer->lock, flags); | |
1623 | ||
1624 | again: | |
818e3dd3 SR |
1625 | /* |
1626 | * This should normally only loop twice. But because the | |
1627 | * start of the reader inserts an empty page, it causes | |
1628 | * a case where we will loop three times. There should be no | |
1629 | * reason to loop four times (that I know of). | |
1630 | */ | |
1631 | if (unlikely(++nr_loops > 3)) { | |
1632 | RB_WARN_ON(cpu_buffer, 1); | |
1633 | reader = NULL; | |
1634 | goto out; | |
1635 | } | |
1636 | ||
d769041f SR |
1637 | reader = cpu_buffer->reader_page; |
1638 | ||
1639 | /* If there's more to read, return this page */ | |
bf41a158 | 1640 | if (cpu_buffer->reader_page->read < rb_page_size(reader)) |
d769041f SR |
1641 | goto out; |
1642 | ||
1643 | /* Never should we have an index greater than the size */ | |
bf41a158 SR |
1644 | RB_WARN_ON(cpu_buffer, |
1645 | cpu_buffer->reader_page->read > rb_page_size(reader)); | |
d769041f SR |
1646 | |
1647 | /* check if we caught up to the tail */ | |
1648 | reader = NULL; | |
bf41a158 | 1649 | if (cpu_buffer->commit_page == cpu_buffer->reader_page) |
d769041f | 1650 | goto out; |
7a8e76a3 SR |
1651 | |
1652 | /* | |
d769041f SR |
1653 | * Splice the empty reader page into the list around the head. |
1654 | * Reset the reader page to size zero. | |
7a8e76a3 | 1655 | */ |
7a8e76a3 | 1656 | |
d769041f SR |
1657 | reader = cpu_buffer->head_page; |
1658 | cpu_buffer->reader_page->list.next = reader->list.next; | |
1659 | cpu_buffer->reader_page->list.prev = reader->list.prev; | |
bf41a158 SR |
1660 | |
1661 | local_set(&cpu_buffer->reader_page->write, 0); | |
1662 | local_set(&cpu_buffer->reader_page->commit, 0); | |
7a8e76a3 | 1663 | |
d769041f SR |
1664 | /* Make the reader page now replace the head */ |
1665 | reader->list.prev->next = &cpu_buffer->reader_page->list; | |
1666 | reader->list.next->prev = &cpu_buffer->reader_page->list; | |
7a8e76a3 SR |
1667 | |
1668 | /* | |
d769041f SR |
1669 | * If the tail is on the reader, then we must set the head |
1670 | * to the inserted page, otherwise we set it one before. | |
7a8e76a3 | 1671 | */ |
d769041f | 1672 | cpu_buffer->head_page = cpu_buffer->reader_page; |
7a8e76a3 | 1673 | |
bf41a158 | 1674 | if (cpu_buffer->commit_page != reader) |
d769041f SR |
1675 | rb_inc_page(cpu_buffer, &cpu_buffer->head_page); |
1676 | ||
1677 | /* Finally update the reader page to the new head */ | |
1678 | cpu_buffer->reader_page = reader; | |
1679 | rb_reset_reader_page(cpu_buffer); | |
1680 | ||
1681 | goto again; | |
1682 | ||
1683 | out: | |
1684 | spin_unlock_irqrestore(&cpu_buffer->lock, flags); | |
1685 | ||
1686 | return reader; | |
1687 | } | |
1688 | ||
1689 | static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer) | |
1690 | { | |
1691 | struct ring_buffer_event *event; | |
1692 | struct buffer_page *reader; | |
1693 | unsigned length; | |
1694 | ||
1695 | reader = rb_get_reader_page(cpu_buffer); | |
7a8e76a3 | 1696 | |
d769041f SR |
1697 | /* This function should not be called when buffer is empty */ |
1698 | BUG_ON(!reader); | |
7a8e76a3 | 1699 | |
d769041f SR |
1700 | event = rb_reader_event(cpu_buffer); |
1701 | ||
1702 | if (event->type == RINGBUF_TYPE_DATA) | |
1703 | cpu_buffer->entries--; | |
1704 | ||
1705 | rb_update_read_stamp(cpu_buffer, event); | |
1706 | ||
1707 | length = rb_event_length(event); | |
6f807acd | 1708 | cpu_buffer->reader_page->read += length; |
7a8e76a3 SR |
1709 | } |
1710 | ||
1711 | static void rb_advance_iter(struct ring_buffer_iter *iter) | |
1712 | { | |
1713 | struct ring_buffer *buffer; | |
1714 | struct ring_buffer_per_cpu *cpu_buffer; | |
1715 | struct ring_buffer_event *event; | |
1716 | unsigned length; | |
1717 | ||
1718 | cpu_buffer = iter->cpu_buffer; | |
1719 | buffer = cpu_buffer->buffer; | |
1720 | ||
1721 | /* | |
1722 | * Check if we are at the end of the buffer. | |
1723 | */ | |
bf41a158 SR |
1724 | if (iter->head >= rb_page_size(iter->head_page)) { |
1725 | BUG_ON(iter->head_page == cpu_buffer->commit_page); | |
d769041f | 1726 | rb_inc_iter(iter); |
7a8e76a3 SR |
1727 | return; |
1728 | } | |
1729 | ||
1730 | event = rb_iter_head_event(iter); | |
1731 | ||
1732 | length = rb_event_length(event); | |
1733 | ||
1734 | /* | |
1735 | * This should not be called to advance the header if we are | |
1736 | * at the tail of the buffer. | |
1737 | */ | |
bf41a158 SR |
1738 | BUG_ON((iter->head_page == cpu_buffer->commit_page) && |
1739 | (iter->head + length > rb_commit_index(cpu_buffer))); | |
7a8e76a3 SR |
1740 | |
1741 | rb_update_iter_read_stamp(iter, event); | |
1742 | ||
1743 | iter->head += length; | |
1744 | ||
1745 | /* check for end of page padding */ | |
bf41a158 SR |
1746 | if ((iter->head >= rb_page_size(iter->head_page)) && |
1747 | (iter->head_page != cpu_buffer->commit_page)) | |
7a8e76a3 SR |
1748 | rb_advance_iter(iter); |
1749 | } | |
1750 | ||
1751 | /** | |
1752 | * ring_buffer_peek - peek at the next event to be read | |
1753 | * @buffer: The ring buffer to read | |
1754 | * @cpu: The cpu to peak at | |
1755 | * @ts: The timestamp counter of this event. | |
1756 | * | |
1757 | * This will return the event that will be read next, but does | |
1758 | * not consume the data. | |
1759 | */ | |
1760 | struct ring_buffer_event * | |
1761 | ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) | |
1762 | { | |
1763 | struct ring_buffer_per_cpu *cpu_buffer; | |
1764 | struct ring_buffer_event *event; | |
d769041f | 1765 | struct buffer_page *reader; |
818e3dd3 | 1766 | int nr_loops = 0; |
7a8e76a3 SR |
1767 | |
1768 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1769 | return NULL; | |
1770 | ||
1771 | cpu_buffer = buffer->buffers[cpu]; | |
1772 | ||
1773 | again: | |
818e3dd3 SR |
1774 | /* |
1775 | * We repeat when a timestamp is encountered. It is possible | |
1776 | * to get multiple timestamps from an interrupt entering just | |
1777 | * as one timestamp is about to be written. The max times | |
1778 | * that this can happen is the number of nested interrupts we | |
1779 | * can have. Nesting 10 deep of interrupts is clearly | |
1780 | * an anomaly. | |
1781 | */ | |
1782 | if (unlikely(++nr_loops > 10)) { | |
1783 | RB_WARN_ON(cpu_buffer, 1); | |
1784 | return NULL; | |
1785 | } | |
1786 | ||
d769041f SR |
1787 | reader = rb_get_reader_page(cpu_buffer); |
1788 | if (!reader) | |
7a8e76a3 SR |
1789 | return NULL; |
1790 | ||
d769041f | 1791 | event = rb_reader_event(cpu_buffer); |
7a8e76a3 SR |
1792 | |
1793 | switch (event->type) { | |
1794 | case RINGBUF_TYPE_PADDING: | |
bf41a158 | 1795 | RB_WARN_ON(cpu_buffer, 1); |
d769041f SR |
1796 | rb_advance_reader(cpu_buffer); |
1797 | return NULL; | |
7a8e76a3 SR |
1798 | |
1799 | case RINGBUF_TYPE_TIME_EXTEND: | |
1800 | /* Internal data, OK to advance */ | |
d769041f | 1801 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
1802 | goto again; |
1803 | ||
1804 | case RINGBUF_TYPE_TIME_STAMP: | |
1805 | /* FIXME: not implemented */ | |
d769041f | 1806 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
1807 | goto again; |
1808 | ||
1809 | case RINGBUF_TYPE_DATA: | |
1810 | if (ts) { | |
1811 | *ts = cpu_buffer->read_stamp + event->time_delta; | |
1812 | ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts); | |
1813 | } | |
1814 | return event; | |
1815 | ||
1816 | default: | |
1817 | BUG(); | |
1818 | } | |
1819 | ||
1820 | return NULL; | |
1821 | } | |
c4f50183 | 1822 | EXPORT_SYMBOL_GPL(ring_buffer_peek); |
7a8e76a3 SR |
1823 | |
1824 | /** | |
1825 | * ring_buffer_iter_peek - peek at the next event to be read | |
1826 | * @iter: The ring buffer iterator | |
1827 | * @ts: The timestamp counter of this event. | |
1828 | * | |
1829 | * This will return the event that will be read next, but does | |
1830 | * not increment the iterator. | |
1831 | */ | |
1832 | struct ring_buffer_event * | |
1833 | ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) | |
1834 | { | |
1835 | struct ring_buffer *buffer; | |
1836 | struct ring_buffer_per_cpu *cpu_buffer; | |
1837 | struct ring_buffer_event *event; | |
818e3dd3 | 1838 | int nr_loops = 0; |
7a8e76a3 SR |
1839 | |
1840 | if (ring_buffer_iter_empty(iter)) | |
1841 | return NULL; | |
1842 | ||
1843 | cpu_buffer = iter->cpu_buffer; | |
1844 | buffer = cpu_buffer->buffer; | |
1845 | ||
1846 | again: | |
818e3dd3 SR |
1847 | /* |
1848 | * We repeat when a timestamp is encountered. It is possible | |
1849 | * to get multiple timestamps from an interrupt entering just | |
1850 | * as one timestamp is about to be written. The max times | |
1851 | * that this can happen is the number of nested interrupts we | |
1852 | * can have. Nesting 10 deep of interrupts is clearly | |
1853 | * an anomaly. | |
1854 | */ | |
1855 | if (unlikely(++nr_loops > 10)) { | |
1856 | RB_WARN_ON(cpu_buffer, 1); | |
1857 | return NULL; | |
1858 | } | |
1859 | ||
7a8e76a3 SR |
1860 | if (rb_per_cpu_empty(cpu_buffer)) |
1861 | return NULL; | |
1862 | ||
1863 | event = rb_iter_head_event(iter); | |
1864 | ||
1865 | switch (event->type) { | |
1866 | case RINGBUF_TYPE_PADDING: | |
d769041f | 1867 | rb_inc_iter(iter); |
7a8e76a3 SR |
1868 | goto again; |
1869 | ||
1870 | case RINGBUF_TYPE_TIME_EXTEND: | |
1871 | /* Internal data, OK to advance */ | |
1872 | rb_advance_iter(iter); | |
1873 | goto again; | |
1874 | ||
1875 | case RINGBUF_TYPE_TIME_STAMP: | |
1876 | /* FIXME: not implemented */ | |
1877 | rb_advance_iter(iter); | |
1878 | goto again; | |
1879 | ||
1880 | case RINGBUF_TYPE_DATA: | |
1881 | if (ts) { | |
1882 | *ts = iter->read_stamp + event->time_delta; | |
1883 | ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts); | |
1884 | } | |
1885 | return event; | |
1886 | ||
1887 | default: | |
1888 | BUG(); | |
1889 | } | |
1890 | ||
1891 | return NULL; | |
1892 | } | |
c4f50183 | 1893 | EXPORT_SYMBOL_GPL(ring_buffer_iter_peek); |
7a8e76a3 SR |
1894 | |
1895 | /** | |
1896 | * ring_buffer_consume - return an event and consume it | |
1897 | * @buffer: The ring buffer to get the next event from | |
1898 | * | |
1899 | * Returns the next event in the ring buffer, and that event is consumed. | |
1900 | * Meaning, that sequential reads will keep returning a different event, | |
1901 | * and eventually empty the ring buffer if the producer is slower. | |
1902 | */ | |
1903 | struct ring_buffer_event * | |
1904 | ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts) | |
1905 | { | |
1906 | struct ring_buffer_per_cpu *cpu_buffer; | |
1907 | struct ring_buffer_event *event; | |
1908 | ||
1909 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1910 | return NULL; | |
1911 | ||
1912 | event = ring_buffer_peek(buffer, cpu, ts); | |
1913 | if (!event) | |
1914 | return NULL; | |
1915 | ||
1916 | cpu_buffer = buffer->buffers[cpu]; | |
d769041f | 1917 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
1918 | |
1919 | return event; | |
1920 | } | |
c4f50183 | 1921 | EXPORT_SYMBOL_GPL(ring_buffer_consume); |
7a8e76a3 SR |
1922 | |
1923 | /** | |
1924 | * ring_buffer_read_start - start a non consuming read of the buffer | |
1925 | * @buffer: The ring buffer to read from | |
1926 | * @cpu: The cpu buffer to iterate over | |
1927 | * | |
1928 | * This starts up an iteration through the buffer. It also disables | |
1929 | * the recording to the buffer until the reading is finished. | |
1930 | * This prevents the reading from being corrupted. This is not | |
1931 | * a consuming read, so a producer is not expected. | |
1932 | * | |
1933 | * Must be paired with ring_buffer_finish. | |
1934 | */ | |
1935 | struct ring_buffer_iter * | |
1936 | ring_buffer_read_start(struct ring_buffer *buffer, int cpu) | |
1937 | { | |
1938 | struct ring_buffer_per_cpu *cpu_buffer; | |
1939 | struct ring_buffer_iter *iter; | |
d769041f | 1940 | unsigned long flags; |
7a8e76a3 SR |
1941 | |
1942 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1943 | return NULL; | |
1944 | ||
1945 | iter = kmalloc(sizeof(*iter), GFP_KERNEL); | |
1946 | if (!iter) | |
1947 | return NULL; | |
1948 | ||
1949 | cpu_buffer = buffer->buffers[cpu]; | |
1950 | ||
1951 | iter->cpu_buffer = cpu_buffer; | |
1952 | ||
1953 | atomic_inc(&cpu_buffer->record_disabled); | |
1954 | synchronize_sched(); | |
1955 | ||
d769041f SR |
1956 | spin_lock_irqsave(&cpu_buffer->lock, flags); |
1957 | ring_buffer_iter_reset(iter); | |
1958 | spin_unlock_irqrestore(&cpu_buffer->lock, flags); | |
7a8e76a3 SR |
1959 | |
1960 | return iter; | |
1961 | } | |
c4f50183 | 1962 | EXPORT_SYMBOL_GPL(ring_buffer_read_start); |
7a8e76a3 SR |
1963 | |
1964 | /** | |
1965 | * ring_buffer_finish - finish reading the iterator of the buffer | |
1966 | * @iter: The iterator retrieved by ring_buffer_start | |
1967 | * | |
1968 | * This re-enables the recording to the buffer, and frees the | |
1969 | * iterator. | |
1970 | */ | |
1971 | void | |
1972 | ring_buffer_read_finish(struct ring_buffer_iter *iter) | |
1973 | { | |
1974 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
1975 | ||
1976 | atomic_dec(&cpu_buffer->record_disabled); | |
1977 | kfree(iter); | |
1978 | } | |
c4f50183 | 1979 | EXPORT_SYMBOL_GPL(ring_buffer_read_finish); |
7a8e76a3 SR |
1980 | |
1981 | /** | |
1982 | * ring_buffer_read - read the next item in the ring buffer by the iterator | |
1983 | * @iter: The ring buffer iterator | |
1984 | * @ts: The time stamp of the event read. | |
1985 | * | |
1986 | * This reads the next event in the ring buffer and increments the iterator. | |
1987 | */ | |
1988 | struct ring_buffer_event * | |
1989 | ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) | |
1990 | { | |
1991 | struct ring_buffer_event *event; | |
1992 | ||
1993 | event = ring_buffer_iter_peek(iter, ts); | |
1994 | if (!event) | |
1995 | return NULL; | |
1996 | ||
1997 | rb_advance_iter(iter); | |
1998 | ||
1999 | return event; | |
2000 | } | |
c4f50183 | 2001 | EXPORT_SYMBOL_GPL(ring_buffer_read); |
7a8e76a3 SR |
2002 | |
2003 | /** | |
2004 | * ring_buffer_size - return the size of the ring buffer (in bytes) | |
2005 | * @buffer: The ring buffer. | |
2006 | */ | |
2007 | unsigned long ring_buffer_size(struct ring_buffer *buffer) | |
2008 | { | |
2009 | return BUF_PAGE_SIZE * buffer->pages; | |
2010 | } | |
c4f50183 | 2011 | EXPORT_SYMBOL_GPL(ring_buffer_size); |
7a8e76a3 SR |
2012 | |
2013 | static void | |
2014 | rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) | |
2015 | { | |
2016 | cpu_buffer->head_page | |
2017 | = list_entry(cpu_buffer->pages.next, struct buffer_page, list); | |
bf41a158 SR |
2018 | local_set(&cpu_buffer->head_page->write, 0); |
2019 | local_set(&cpu_buffer->head_page->commit, 0); | |
d769041f | 2020 | |
6f807acd | 2021 | cpu_buffer->head_page->read = 0; |
bf41a158 SR |
2022 | |
2023 | cpu_buffer->tail_page = cpu_buffer->head_page; | |
2024 | cpu_buffer->commit_page = cpu_buffer->head_page; | |
2025 | ||
2026 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); | |
2027 | local_set(&cpu_buffer->reader_page->write, 0); | |
2028 | local_set(&cpu_buffer->reader_page->commit, 0); | |
6f807acd | 2029 | cpu_buffer->reader_page->read = 0; |
7a8e76a3 | 2030 | |
7a8e76a3 SR |
2031 | cpu_buffer->overrun = 0; |
2032 | cpu_buffer->entries = 0; | |
2033 | } | |
2034 | ||
2035 | /** | |
2036 | * ring_buffer_reset_cpu - reset a ring buffer per CPU buffer | |
2037 | * @buffer: The ring buffer to reset a per cpu buffer of | |
2038 | * @cpu: The CPU buffer to be reset | |
2039 | */ | |
2040 | void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) | |
2041 | { | |
2042 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
2043 | unsigned long flags; | |
2044 | ||
2045 | if (!cpu_isset(cpu, buffer->cpumask)) | |
2046 | return; | |
2047 | ||
d769041f | 2048 | spin_lock_irqsave(&cpu_buffer->lock, flags); |
7a8e76a3 SR |
2049 | |
2050 | rb_reset_cpu(cpu_buffer); | |
2051 | ||
d769041f | 2052 | spin_unlock_irqrestore(&cpu_buffer->lock, flags); |
7a8e76a3 | 2053 | } |
c4f50183 | 2054 | EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); |
7a8e76a3 SR |
2055 | |
2056 | /** | |
2057 | * ring_buffer_reset - reset a ring buffer | |
2058 | * @buffer: The ring buffer to reset all cpu buffers | |
2059 | */ | |
2060 | void ring_buffer_reset(struct ring_buffer *buffer) | |
2061 | { | |
7a8e76a3 SR |
2062 | int cpu; |
2063 | ||
7a8e76a3 | 2064 | for_each_buffer_cpu(buffer, cpu) |
d769041f | 2065 | ring_buffer_reset_cpu(buffer, cpu); |
7a8e76a3 | 2066 | } |
c4f50183 | 2067 | EXPORT_SYMBOL_GPL(ring_buffer_reset); |
7a8e76a3 SR |
2068 | |
2069 | /** | |
2070 | * rind_buffer_empty - is the ring buffer empty? | |
2071 | * @buffer: The ring buffer to test | |
2072 | */ | |
2073 | int ring_buffer_empty(struct ring_buffer *buffer) | |
2074 | { | |
2075 | struct ring_buffer_per_cpu *cpu_buffer; | |
2076 | int cpu; | |
2077 | ||
2078 | /* yes this is racy, but if you don't like the race, lock the buffer */ | |
2079 | for_each_buffer_cpu(buffer, cpu) { | |
2080 | cpu_buffer = buffer->buffers[cpu]; | |
2081 | if (!rb_per_cpu_empty(cpu_buffer)) | |
2082 | return 0; | |
2083 | } | |
2084 | return 1; | |
2085 | } | |
c4f50183 | 2086 | EXPORT_SYMBOL_GPL(ring_buffer_empty); |
7a8e76a3 SR |
2087 | |
2088 | /** | |
2089 | * ring_buffer_empty_cpu - is a cpu buffer of a ring buffer empty? | |
2090 | * @buffer: The ring buffer | |
2091 | * @cpu: The CPU buffer to test | |
2092 | */ | |
2093 | int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) | |
2094 | { | |
2095 | struct ring_buffer_per_cpu *cpu_buffer; | |
2096 | ||
2097 | if (!cpu_isset(cpu, buffer->cpumask)) | |
2098 | return 1; | |
2099 | ||
2100 | cpu_buffer = buffer->buffers[cpu]; | |
2101 | return rb_per_cpu_empty(cpu_buffer); | |
2102 | } | |
c4f50183 | 2103 | EXPORT_SYMBOL_GPL(ring_buffer_empty_cpu); |
7a8e76a3 SR |
2104 | |
2105 | /** | |
2106 | * ring_buffer_swap_cpu - swap a CPU buffer between two ring buffers | |
2107 | * @buffer_a: One buffer to swap with | |
2108 | * @buffer_b: The other buffer to swap with | |
2109 | * | |
2110 | * This function is useful for tracers that want to take a "snapshot" | |
2111 | * of a CPU buffer and has another back up buffer lying around. | |
2112 | * it is expected that the tracer handles the cpu buffer not being | |
2113 | * used at the moment. | |
2114 | */ | |
2115 | int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, | |
2116 | struct ring_buffer *buffer_b, int cpu) | |
2117 | { | |
2118 | struct ring_buffer_per_cpu *cpu_buffer_a; | |
2119 | struct ring_buffer_per_cpu *cpu_buffer_b; | |
2120 | ||
2121 | if (!cpu_isset(cpu, buffer_a->cpumask) || | |
2122 | !cpu_isset(cpu, buffer_b->cpumask)) | |
2123 | return -EINVAL; | |
2124 | ||
2125 | /* At least make sure the two buffers are somewhat the same */ | |
2126 | if (buffer_a->size != buffer_b->size || | |
2127 | buffer_a->pages != buffer_b->pages) | |
2128 | return -EINVAL; | |
2129 | ||
2130 | cpu_buffer_a = buffer_a->buffers[cpu]; | |
2131 | cpu_buffer_b = buffer_b->buffers[cpu]; | |
2132 | ||
2133 | /* | |
2134 | * We can't do a synchronize_sched here because this | |
2135 | * function can be called in atomic context. | |
2136 | * Normally this will be called from the same CPU as cpu. | |
2137 | * If not it's up to the caller to protect this. | |
2138 | */ | |
2139 | atomic_inc(&cpu_buffer_a->record_disabled); | |
2140 | atomic_inc(&cpu_buffer_b->record_disabled); | |
2141 | ||
2142 | buffer_a->buffers[cpu] = cpu_buffer_b; | |
2143 | buffer_b->buffers[cpu] = cpu_buffer_a; | |
2144 | ||
2145 | cpu_buffer_b->buffer = buffer_a; | |
2146 | cpu_buffer_a->buffer = buffer_b; | |
2147 | ||
2148 | atomic_dec(&cpu_buffer_a->record_disabled); | |
2149 | atomic_dec(&cpu_buffer_b->record_disabled); | |
2150 | ||
2151 | return 0; | |
2152 | } | |
c4f50183 | 2153 | EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu); |
7a8e76a3 | 2154 | |
a3583244 SR |
2155 | static ssize_t |
2156 | rb_simple_read(struct file *filp, char __user *ubuf, | |
2157 | size_t cnt, loff_t *ppos) | |
2158 | { | |
2159 | int *p = filp->private_data; | |
2160 | char buf[64]; | |
2161 | int r; | |
2162 | ||
2163 | /* !ring_buffers_off == tracing_on */ | |
2164 | r = sprintf(buf, "%d\n", !*p); | |
2165 | ||
2166 | return simple_read_from_buffer(ubuf, cnt, ppos, buf, r); | |
2167 | } | |
2168 | ||
2169 | static ssize_t | |
2170 | rb_simple_write(struct file *filp, const char __user *ubuf, | |
2171 | size_t cnt, loff_t *ppos) | |
2172 | { | |
2173 | int *p = filp->private_data; | |
2174 | char buf[64]; | |
2175 | long val; | |
2176 | int ret; | |
2177 | ||
2178 | if (cnt >= sizeof(buf)) | |
2179 | return -EINVAL; | |
2180 | ||
2181 | if (copy_from_user(&buf, ubuf, cnt)) | |
2182 | return -EFAULT; | |
2183 | ||
2184 | buf[cnt] = 0; | |
2185 | ||
2186 | ret = strict_strtoul(buf, 10, &val); | |
2187 | if (ret < 0) | |
2188 | return ret; | |
2189 | ||
2190 | /* !ring_buffers_off == tracing_on */ | |
2191 | *p = !val; | |
2192 | ||
2193 | (*ppos)++; | |
2194 | ||
2195 | return cnt; | |
2196 | } | |
2197 | ||
2198 | static struct file_operations rb_simple_fops = { | |
2199 | .open = tracing_open_generic, | |
2200 | .read = rb_simple_read, | |
2201 | .write = rb_simple_write, | |
2202 | }; | |
2203 | ||
2204 | ||
2205 | static __init int rb_init_debugfs(void) | |
2206 | { | |
2207 | struct dentry *d_tracer; | |
2208 | struct dentry *entry; | |
2209 | ||
2210 | d_tracer = tracing_init_dentry(); | |
2211 | ||
2212 | entry = debugfs_create_file("tracing_on", 0644, d_tracer, | |
2213 | &ring_buffers_off, &rb_simple_fops); | |
2214 | if (!entry) | |
2215 | pr_warning("Could not create debugfs 'tracing_on' entry\n"); | |
2216 | ||
2217 | return 0; | |
2218 | } | |
2219 | ||
2220 | fs_initcall(rb_init_debugfs); |