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 | ||
182e9f5f SR |
19 | #include "trace.h" |
20 | ||
033601a3 SR |
21 | /* |
22 | * A fast way to enable or disable all ring buffers is to | |
23 | * call tracing_on or tracing_off. Turning off the ring buffers | |
24 | * prevents all ring buffers from being recorded to. | |
25 | * Turning this switch on, makes it OK to write to the | |
26 | * ring buffer, if the ring buffer is enabled itself. | |
27 | * | |
28 | * There's three layers that must be on in order to write | |
29 | * to the ring buffer. | |
30 | * | |
31 | * 1) This global flag must be set. | |
32 | * 2) The ring buffer must be enabled for recording. | |
33 | * 3) The per cpu buffer must be enabled for recording. | |
34 | * | |
35 | * In case of an anomaly, this global flag has a bit set that | |
36 | * will permantly disable all ring buffers. | |
37 | */ | |
38 | ||
39 | /* | |
40 | * Global flag to disable all recording to ring buffers | |
41 | * This has two bits: ON, DISABLED | |
42 | * | |
43 | * ON DISABLED | |
44 | * ---- ---------- | |
45 | * 0 0 : ring buffers are off | |
46 | * 1 0 : ring buffers are on | |
47 | * X 1 : ring buffers are permanently disabled | |
48 | */ | |
49 | ||
50 | enum { | |
51 | RB_BUFFERS_ON_BIT = 0, | |
52 | RB_BUFFERS_DISABLED_BIT = 1, | |
53 | }; | |
54 | ||
55 | enum { | |
56 | RB_BUFFERS_ON = 1 << RB_BUFFERS_ON_BIT, | |
57 | RB_BUFFERS_DISABLED = 1 << RB_BUFFERS_DISABLED_BIT, | |
58 | }; | |
59 | ||
60 | static long ring_buffer_flags __read_mostly = RB_BUFFERS_ON; | |
a3583244 SR |
61 | |
62 | /** | |
63 | * tracing_on - enable all tracing buffers | |
64 | * | |
65 | * This function enables all tracing buffers that may have been | |
66 | * disabled with tracing_off. | |
67 | */ | |
68 | void tracing_on(void) | |
69 | { | |
033601a3 | 70 | set_bit(RB_BUFFERS_ON_BIT, &ring_buffer_flags); |
a3583244 | 71 | } |
c4f50183 | 72 | EXPORT_SYMBOL_GPL(tracing_on); |
a3583244 SR |
73 | |
74 | /** | |
75 | * tracing_off - turn off all tracing buffers | |
76 | * | |
77 | * This function stops all tracing buffers from recording data. | |
78 | * It does not disable any overhead the tracers themselves may | |
79 | * be causing. This function simply causes all recording to | |
80 | * the ring buffers to fail. | |
81 | */ | |
82 | void tracing_off(void) | |
83 | { | |
033601a3 SR |
84 | clear_bit(RB_BUFFERS_ON_BIT, &ring_buffer_flags); |
85 | } | |
c4f50183 | 86 | EXPORT_SYMBOL_GPL(tracing_off); |
033601a3 SR |
87 | |
88 | /** | |
89 | * tracing_off_permanent - permanently disable ring buffers | |
90 | * | |
91 | * This function, once called, will disable all ring buffers | |
92 | * permanenty. | |
93 | */ | |
94 | void tracing_off_permanent(void) | |
95 | { | |
96 | set_bit(RB_BUFFERS_DISABLED_BIT, &ring_buffer_flags); | |
a3583244 SR |
97 | } |
98 | ||
d06bbd66 IM |
99 | #include "trace.h" |
100 | ||
7a8e76a3 SR |
101 | /* Up this if you want to test the TIME_EXTENTS and normalization */ |
102 | #define DEBUG_SHIFT 0 | |
103 | ||
104 | /* FIXME!!! */ | |
105 | u64 ring_buffer_time_stamp(int cpu) | |
106 | { | |
47e74f2b SR |
107 | u64 time; |
108 | ||
109 | preempt_disable_notrace(); | |
7a8e76a3 | 110 | /* shift to debug/test normalization and TIME_EXTENTS */ |
47e74f2b | 111 | time = sched_clock() << DEBUG_SHIFT; |
2c2d7329 | 112 | preempt_enable_no_resched_notrace(); |
47e74f2b SR |
113 | |
114 | return time; | |
7a8e76a3 | 115 | } |
c4f50183 | 116 | EXPORT_SYMBOL_GPL(ring_buffer_time_stamp); |
7a8e76a3 SR |
117 | |
118 | void ring_buffer_normalize_time_stamp(int cpu, u64 *ts) | |
119 | { | |
120 | /* Just stupid testing the normalize function and deltas */ | |
121 | *ts >>= DEBUG_SHIFT; | |
122 | } | |
c4f50183 | 123 | EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp); |
7a8e76a3 SR |
124 | |
125 | #define RB_EVNT_HDR_SIZE (sizeof(struct ring_buffer_event)) | |
126 | #define RB_ALIGNMENT_SHIFT 2 | |
127 | #define RB_ALIGNMENT (1 << RB_ALIGNMENT_SHIFT) | |
128 | #define RB_MAX_SMALL_DATA 28 | |
129 | ||
130 | enum { | |
131 | RB_LEN_TIME_EXTEND = 8, | |
132 | RB_LEN_TIME_STAMP = 16, | |
133 | }; | |
134 | ||
135 | /* inline for ring buffer fast paths */ | |
136 | static inline unsigned | |
137 | rb_event_length(struct ring_buffer_event *event) | |
138 | { | |
139 | unsigned length; | |
140 | ||
141 | switch (event->type) { | |
142 | case RINGBUF_TYPE_PADDING: | |
143 | /* undefined */ | |
144 | return -1; | |
145 | ||
146 | case RINGBUF_TYPE_TIME_EXTEND: | |
147 | return RB_LEN_TIME_EXTEND; | |
148 | ||
149 | case RINGBUF_TYPE_TIME_STAMP: | |
150 | return RB_LEN_TIME_STAMP; | |
151 | ||
152 | case RINGBUF_TYPE_DATA: | |
153 | if (event->len) | |
154 | length = event->len << RB_ALIGNMENT_SHIFT; | |
155 | else | |
156 | length = event->array[0]; | |
157 | return length + RB_EVNT_HDR_SIZE; | |
158 | default: | |
159 | BUG(); | |
160 | } | |
161 | /* not hit */ | |
162 | return 0; | |
163 | } | |
164 | ||
165 | /** | |
166 | * ring_buffer_event_length - return the length of the event | |
167 | * @event: the event to get the length of | |
168 | */ | |
169 | unsigned ring_buffer_event_length(struct ring_buffer_event *event) | |
170 | { | |
171 | return rb_event_length(event); | |
172 | } | |
c4f50183 | 173 | EXPORT_SYMBOL_GPL(ring_buffer_event_length); |
7a8e76a3 SR |
174 | |
175 | /* inline for ring buffer fast paths */ | |
176 | static inline void * | |
177 | rb_event_data(struct ring_buffer_event *event) | |
178 | { | |
179 | BUG_ON(event->type != RINGBUF_TYPE_DATA); | |
180 | /* If length is in len field, then array[0] has the data */ | |
181 | if (event->len) | |
182 | return (void *)&event->array[0]; | |
183 | /* Otherwise length is in array[0] and array[1] has the data */ | |
184 | return (void *)&event->array[1]; | |
185 | } | |
186 | ||
187 | /** | |
188 | * ring_buffer_event_data - return the data of the event | |
189 | * @event: the event to get the data from | |
190 | */ | |
191 | void *ring_buffer_event_data(struct ring_buffer_event *event) | |
192 | { | |
193 | return rb_event_data(event); | |
194 | } | |
c4f50183 | 195 | EXPORT_SYMBOL_GPL(ring_buffer_event_data); |
7a8e76a3 SR |
196 | |
197 | #define for_each_buffer_cpu(buffer, cpu) \ | |
198 | for_each_cpu_mask(cpu, buffer->cpumask) | |
199 | ||
200 | #define TS_SHIFT 27 | |
201 | #define TS_MASK ((1ULL << TS_SHIFT) - 1) | |
202 | #define TS_DELTA_TEST (~TS_MASK) | |
203 | ||
abc9b56d | 204 | struct buffer_data_page { |
e4c2ce82 | 205 | u64 time_stamp; /* page time stamp */ |
bf41a158 | 206 | local_t commit; /* write commited index */ |
abc9b56d SR |
207 | unsigned char data[]; /* data of buffer page */ |
208 | }; | |
209 | ||
210 | struct buffer_page { | |
211 | local_t write; /* index for next write */ | |
6f807acd | 212 | unsigned read; /* index for next read */ |
e4c2ce82 | 213 | struct list_head list; /* list of free pages */ |
abc9b56d | 214 | struct buffer_data_page *page; /* Actual data page */ |
7a8e76a3 SR |
215 | }; |
216 | ||
044fa782 | 217 | static void rb_init_page(struct buffer_data_page *bpage) |
abc9b56d | 218 | { |
044fa782 | 219 | local_set(&bpage->commit, 0); |
abc9b56d SR |
220 | } |
221 | ||
ed56829c SR |
222 | /* |
223 | * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing | |
224 | * this issue out. | |
225 | */ | |
226 | static inline void free_buffer_page(struct buffer_page *bpage) | |
227 | { | |
e4c2ce82 | 228 | if (bpage->page) |
6ae2a076 | 229 | free_page((unsigned long)bpage->page); |
e4c2ce82 | 230 | kfree(bpage); |
ed56829c SR |
231 | } |
232 | ||
7a8e76a3 SR |
233 | /* |
234 | * We need to fit the time_stamp delta into 27 bits. | |
235 | */ | |
236 | static inline int test_time_stamp(u64 delta) | |
237 | { | |
238 | if (delta & TS_DELTA_TEST) | |
239 | return 1; | |
240 | return 0; | |
241 | } | |
242 | ||
abc9b56d | 243 | #define BUF_PAGE_SIZE (PAGE_SIZE - sizeof(struct buffer_data_page)) |
7a8e76a3 SR |
244 | |
245 | /* | |
246 | * head_page == tail_page && head == tail then buffer is empty. | |
247 | */ | |
248 | struct ring_buffer_per_cpu { | |
249 | int cpu; | |
250 | struct ring_buffer *buffer; | |
f83c9d0f | 251 | spinlock_t reader_lock; /* serialize readers */ |
3e03fb7f | 252 | raw_spinlock_t lock; |
7a8e76a3 SR |
253 | struct lock_class_key lock_key; |
254 | struct list_head pages; | |
6f807acd SR |
255 | struct buffer_page *head_page; /* read from head */ |
256 | struct buffer_page *tail_page; /* write to tail */ | |
bf41a158 | 257 | struct buffer_page *commit_page; /* commited pages */ |
d769041f | 258 | struct buffer_page *reader_page; |
7a8e76a3 SR |
259 | unsigned long overrun; |
260 | unsigned long entries; | |
261 | u64 write_stamp; | |
262 | u64 read_stamp; | |
263 | atomic_t record_disabled; | |
264 | }; | |
265 | ||
266 | struct ring_buffer { | |
7a8e76a3 SR |
267 | unsigned pages; |
268 | unsigned flags; | |
269 | int cpus; | |
270 | cpumask_t cpumask; | |
271 | atomic_t record_disabled; | |
272 | ||
273 | struct mutex mutex; | |
274 | ||
275 | struct ring_buffer_per_cpu **buffers; | |
276 | }; | |
277 | ||
278 | struct ring_buffer_iter { | |
279 | struct ring_buffer_per_cpu *cpu_buffer; | |
280 | unsigned long head; | |
281 | struct buffer_page *head_page; | |
282 | u64 read_stamp; | |
283 | }; | |
284 | ||
f536aafc | 285 | /* buffer may be either ring_buffer or ring_buffer_per_cpu */ |
bf41a158 | 286 | #define RB_WARN_ON(buffer, cond) \ |
3e89c7bb SR |
287 | ({ \ |
288 | int _____ret = unlikely(cond); \ | |
289 | if (_____ret) { \ | |
bf41a158 SR |
290 | atomic_inc(&buffer->record_disabled); \ |
291 | WARN_ON(1); \ | |
292 | } \ | |
3e89c7bb SR |
293 | _____ret; \ |
294 | }) | |
f536aafc | 295 | |
7a8e76a3 SR |
296 | /** |
297 | * check_pages - integrity check of buffer pages | |
298 | * @cpu_buffer: CPU buffer with pages to test | |
299 | * | |
300 | * As a safty measure we check to make sure the data pages have not | |
301 | * been corrupted. | |
302 | */ | |
303 | static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) | |
304 | { | |
305 | struct list_head *head = &cpu_buffer->pages; | |
044fa782 | 306 | struct buffer_page *bpage, *tmp; |
7a8e76a3 | 307 | |
3e89c7bb SR |
308 | if (RB_WARN_ON(cpu_buffer, head->next->prev != head)) |
309 | return -1; | |
310 | if (RB_WARN_ON(cpu_buffer, head->prev->next != head)) | |
311 | return -1; | |
7a8e76a3 | 312 | |
044fa782 | 313 | list_for_each_entry_safe(bpage, tmp, head, list) { |
3e89c7bb | 314 | if (RB_WARN_ON(cpu_buffer, |
044fa782 | 315 | bpage->list.next->prev != &bpage->list)) |
3e89c7bb SR |
316 | return -1; |
317 | if (RB_WARN_ON(cpu_buffer, | |
044fa782 | 318 | bpage->list.prev->next != &bpage->list)) |
3e89c7bb | 319 | return -1; |
7a8e76a3 SR |
320 | } |
321 | ||
322 | return 0; | |
323 | } | |
324 | ||
7a8e76a3 SR |
325 | static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, |
326 | unsigned nr_pages) | |
327 | { | |
328 | struct list_head *head = &cpu_buffer->pages; | |
044fa782 | 329 | struct buffer_page *bpage, *tmp; |
7a8e76a3 SR |
330 | unsigned long addr; |
331 | LIST_HEAD(pages); | |
332 | unsigned i; | |
333 | ||
334 | for (i = 0; i < nr_pages; i++) { | |
044fa782 | 335 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
aa1e0e3b | 336 | GFP_KERNEL, cpu_to_node(cpu_buffer->cpu)); |
044fa782 | 337 | if (!bpage) |
e4c2ce82 | 338 | goto free_pages; |
044fa782 | 339 | list_add(&bpage->list, &pages); |
e4c2ce82 | 340 | |
7a8e76a3 SR |
341 | addr = __get_free_page(GFP_KERNEL); |
342 | if (!addr) | |
343 | goto free_pages; | |
044fa782 SR |
344 | bpage->page = (void *)addr; |
345 | rb_init_page(bpage->page); | |
7a8e76a3 SR |
346 | } |
347 | ||
348 | list_splice(&pages, head); | |
349 | ||
350 | rb_check_pages(cpu_buffer); | |
351 | ||
352 | return 0; | |
353 | ||
354 | free_pages: | |
044fa782 SR |
355 | list_for_each_entry_safe(bpage, tmp, &pages, list) { |
356 | list_del_init(&bpage->list); | |
357 | free_buffer_page(bpage); | |
7a8e76a3 SR |
358 | } |
359 | return -ENOMEM; | |
360 | } | |
361 | ||
362 | static struct ring_buffer_per_cpu * | |
363 | rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu) | |
364 | { | |
365 | struct ring_buffer_per_cpu *cpu_buffer; | |
044fa782 | 366 | struct buffer_page *bpage; |
d769041f | 367 | unsigned long addr; |
7a8e76a3 SR |
368 | int ret; |
369 | ||
370 | cpu_buffer = kzalloc_node(ALIGN(sizeof(*cpu_buffer), cache_line_size()), | |
371 | GFP_KERNEL, cpu_to_node(cpu)); | |
372 | if (!cpu_buffer) | |
373 | return NULL; | |
374 | ||
375 | cpu_buffer->cpu = cpu; | |
376 | cpu_buffer->buffer = buffer; | |
f83c9d0f | 377 | spin_lock_init(&cpu_buffer->reader_lock); |
3e03fb7f | 378 | cpu_buffer->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; |
7a8e76a3 SR |
379 | INIT_LIST_HEAD(&cpu_buffer->pages); |
380 | ||
044fa782 | 381 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
e4c2ce82 | 382 | GFP_KERNEL, cpu_to_node(cpu)); |
044fa782 | 383 | if (!bpage) |
e4c2ce82 SR |
384 | goto fail_free_buffer; |
385 | ||
044fa782 | 386 | cpu_buffer->reader_page = bpage; |
d769041f SR |
387 | addr = __get_free_page(GFP_KERNEL); |
388 | if (!addr) | |
e4c2ce82 | 389 | goto fail_free_reader; |
044fa782 SR |
390 | bpage->page = (void *)addr; |
391 | rb_init_page(bpage->page); | |
e4c2ce82 | 392 | |
d769041f | 393 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); |
d769041f | 394 | |
7a8e76a3 SR |
395 | ret = rb_allocate_pages(cpu_buffer, buffer->pages); |
396 | if (ret < 0) | |
d769041f | 397 | goto fail_free_reader; |
7a8e76a3 SR |
398 | |
399 | cpu_buffer->head_page | |
400 | = list_entry(cpu_buffer->pages.next, struct buffer_page, list); | |
bf41a158 | 401 | cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; |
7a8e76a3 SR |
402 | |
403 | return cpu_buffer; | |
404 | ||
d769041f SR |
405 | fail_free_reader: |
406 | free_buffer_page(cpu_buffer->reader_page); | |
407 | ||
7a8e76a3 SR |
408 | fail_free_buffer: |
409 | kfree(cpu_buffer); | |
410 | return NULL; | |
411 | } | |
412 | ||
413 | static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) | |
414 | { | |
415 | struct list_head *head = &cpu_buffer->pages; | |
044fa782 | 416 | struct buffer_page *bpage, *tmp; |
7a8e76a3 | 417 | |
d769041f SR |
418 | list_del_init(&cpu_buffer->reader_page->list); |
419 | free_buffer_page(cpu_buffer->reader_page); | |
420 | ||
044fa782 SR |
421 | list_for_each_entry_safe(bpage, tmp, head, list) { |
422 | list_del_init(&bpage->list); | |
423 | free_buffer_page(bpage); | |
7a8e76a3 SR |
424 | } |
425 | kfree(cpu_buffer); | |
426 | } | |
427 | ||
a7b13743 SR |
428 | /* |
429 | * Causes compile errors if the struct buffer_page gets bigger | |
430 | * than the struct page. | |
431 | */ | |
432 | extern int ring_buffer_page_too_big(void); | |
433 | ||
7a8e76a3 SR |
434 | /** |
435 | * ring_buffer_alloc - allocate a new ring_buffer | |
68814b58 | 436 | * @size: the size in bytes per cpu that is needed. |
7a8e76a3 SR |
437 | * @flags: attributes to set for the ring buffer. |
438 | * | |
439 | * Currently the only flag that is available is the RB_FL_OVERWRITE | |
440 | * flag. This flag means that the buffer will overwrite old data | |
441 | * when the buffer wraps. If this flag is not set, the buffer will | |
442 | * drop data when the tail hits the head. | |
443 | */ | |
444 | struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags) | |
445 | { | |
446 | struct ring_buffer *buffer; | |
447 | int bsize; | |
448 | int cpu; | |
449 | ||
a7b13743 SR |
450 | /* Paranoid! Optimizes out when all is well */ |
451 | if (sizeof(struct buffer_page) > sizeof(struct page)) | |
452 | ring_buffer_page_too_big(); | |
453 | ||
454 | ||
7a8e76a3 SR |
455 | /* keep it in its own cache line */ |
456 | buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()), | |
457 | GFP_KERNEL); | |
458 | if (!buffer) | |
459 | return NULL; | |
460 | ||
461 | buffer->pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); | |
462 | buffer->flags = flags; | |
463 | ||
464 | /* need at least two pages */ | |
465 | if (buffer->pages == 1) | |
466 | buffer->pages++; | |
467 | ||
468 | buffer->cpumask = cpu_possible_map; | |
469 | buffer->cpus = nr_cpu_ids; | |
470 | ||
471 | bsize = sizeof(void *) * nr_cpu_ids; | |
472 | buffer->buffers = kzalloc(ALIGN(bsize, cache_line_size()), | |
473 | GFP_KERNEL); | |
474 | if (!buffer->buffers) | |
475 | goto fail_free_buffer; | |
476 | ||
477 | for_each_buffer_cpu(buffer, cpu) { | |
478 | buffer->buffers[cpu] = | |
479 | rb_allocate_cpu_buffer(buffer, cpu); | |
480 | if (!buffer->buffers[cpu]) | |
481 | goto fail_free_buffers; | |
482 | } | |
483 | ||
484 | mutex_init(&buffer->mutex); | |
485 | ||
486 | return buffer; | |
487 | ||
488 | fail_free_buffers: | |
489 | for_each_buffer_cpu(buffer, cpu) { | |
490 | if (buffer->buffers[cpu]) | |
491 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
492 | } | |
493 | kfree(buffer->buffers); | |
494 | ||
495 | fail_free_buffer: | |
496 | kfree(buffer); | |
497 | return NULL; | |
498 | } | |
c4f50183 | 499 | EXPORT_SYMBOL_GPL(ring_buffer_alloc); |
7a8e76a3 SR |
500 | |
501 | /** | |
502 | * ring_buffer_free - free a ring buffer. | |
503 | * @buffer: the buffer to free. | |
504 | */ | |
505 | void | |
506 | ring_buffer_free(struct ring_buffer *buffer) | |
507 | { | |
508 | int cpu; | |
509 | ||
510 | for_each_buffer_cpu(buffer, cpu) | |
511 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
512 | ||
513 | kfree(buffer); | |
514 | } | |
c4f50183 | 515 | EXPORT_SYMBOL_GPL(ring_buffer_free); |
7a8e76a3 SR |
516 | |
517 | static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer); | |
518 | ||
519 | static void | |
520 | rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages) | |
521 | { | |
044fa782 | 522 | struct buffer_page *bpage; |
7a8e76a3 SR |
523 | struct list_head *p; |
524 | unsigned i; | |
525 | ||
526 | atomic_inc(&cpu_buffer->record_disabled); | |
527 | synchronize_sched(); | |
528 | ||
529 | for (i = 0; i < nr_pages; i++) { | |
3e89c7bb SR |
530 | if (RB_WARN_ON(cpu_buffer, list_empty(&cpu_buffer->pages))) |
531 | return; | |
7a8e76a3 | 532 | p = cpu_buffer->pages.next; |
044fa782 SR |
533 | bpage = list_entry(p, struct buffer_page, list); |
534 | list_del_init(&bpage->list); | |
535 | free_buffer_page(bpage); | |
7a8e76a3 | 536 | } |
3e89c7bb SR |
537 | if (RB_WARN_ON(cpu_buffer, list_empty(&cpu_buffer->pages))) |
538 | return; | |
7a8e76a3 SR |
539 | |
540 | rb_reset_cpu(cpu_buffer); | |
541 | ||
542 | rb_check_pages(cpu_buffer); | |
543 | ||
544 | atomic_dec(&cpu_buffer->record_disabled); | |
545 | ||
546 | } | |
547 | ||
548 | static void | |
549 | rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer, | |
550 | struct list_head *pages, unsigned nr_pages) | |
551 | { | |
044fa782 | 552 | struct buffer_page *bpage; |
7a8e76a3 SR |
553 | struct list_head *p; |
554 | unsigned i; | |
555 | ||
556 | atomic_inc(&cpu_buffer->record_disabled); | |
557 | synchronize_sched(); | |
558 | ||
559 | for (i = 0; i < nr_pages; i++) { | |
3e89c7bb SR |
560 | if (RB_WARN_ON(cpu_buffer, list_empty(pages))) |
561 | return; | |
7a8e76a3 | 562 | p = pages->next; |
044fa782 SR |
563 | bpage = list_entry(p, struct buffer_page, list); |
564 | list_del_init(&bpage->list); | |
565 | list_add_tail(&bpage->list, &cpu_buffer->pages); | |
7a8e76a3 SR |
566 | } |
567 | rb_reset_cpu(cpu_buffer); | |
568 | ||
569 | rb_check_pages(cpu_buffer); | |
570 | ||
571 | atomic_dec(&cpu_buffer->record_disabled); | |
572 | } | |
573 | ||
574 | /** | |
575 | * ring_buffer_resize - resize the ring buffer | |
576 | * @buffer: the buffer to resize. | |
577 | * @size: the new size. | |
578 | * | |
579 | * The tracer is responsible for making sure that the buffer is | |
580 | * not being used while changing the size. | |
581 | * Note: We may be able to change the above requirement by using | |
582 | * RCU synchronizations. | |
583 | * | |
584 | * Minimum size is 2 * BUF_PAGE_SIZE. | |
585 | * | |
586 | * Returns -1 on failure. | |
587 | */ | |
588 | int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size) | |
589 | { | |
590 | struct ring_buffer_per_cpu *cpu_buffer; | |
591 | unsigned nr_pages, rm_pages, new_pages; | |
044fa782 | 592 | struct buffer_page *bpage, *tmp; |
7a8e76a3 SR |
593 | unsigned long buffer_size; |
594 | unsigned long addr; | |
595 | LIST_HEAD(pages); | |
596 | int i, cpu; | |
597 | ||
ee51a1de IM |
598 | /* |
599 | * Always succeed at resizing a non-existent buffer: | |
600 | */ | |
601 | if (!buffer) | |
602 | return size; | |
603 | ||
7a8e76a3 SR |
604 | size = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
605 | size *= BUF_PAGE_SIZE; | |
606 | buffer_size = buffer->pages * BUF_PAGE_SIZE; | |
607 | ||
608 | /* we need a minimum of two pages */ | |
609 | if (size < BUF_PAGE_SIZE * 2) | |
610 | size = BUF_PAGE_SIZE * 2; | |
611 | ||
612 | if (size == buffer_size) | |
613 | return size; | |
614 | ||
615 | mutex_lock(&buffer->mutex); | |
616 | ||
617 | nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); | |
618 | ||
619 | if (size < buffer_size) { | |
620 | ||
621 | /* easy case, just free pages */ | |
3e89c7bb SR |
622 | if (RB_WARN_ON(buffer, nr_pages >= buffer->pages)) { |
623 | mutex_unlock(&buffer->mutex); | |
624 | return -1; | |
625 | } | |
7a8e76a3 SR |
626 | |
627 | rm_pages = buffer->pages - nr_pages; | |
628 | ||
629 | for_each_buffer_cpu(buffer, cpu) { | |
630 | cpu_buffer = buffer->buffers[cpu]; | |
631 | rb_remove_pages(cpu_buffer, rm_pages); | |
632 | } | |
633 | goto out; | |
634 | } | |
635 | ||
636 | /* | |
637 | * This is a bit more difficult. We only want to add pages | |
638 | * when we can allocate enough for all CPUs. We do this | |
639 | * by allocating all the pages and storing them on a local | |
640 | * link list. If we succeed in our allocation, then we | |
641 | * add these pages to the cpu_buffers. Otherwise we just free | |
642 | * them all and return -ENOMEM; | |
643 | */ | |
3e89c7bb SR |
644 | if (RB_WARN_ON(buffer, nr_pages <= buffer->pages)) { |
645 | mutex_unlock(&buffer->mutex); | |
646 | return -1; | |
647 | } | |
f536aafc | 648 | |
7a8e76a3 SR |
649 | new_pages = nr_pages - buffer->pages; |
650 | ||
651 | for_each_buffer_cpu(buffer, cpu) { | |
652 | for (i = 0; i < new_pages; i++) { | |
044fa782 | 653 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), |
e4c2ce82 SR |
654 | cache_line_size()), |
655 | GFP_KERNEL, cpu_to_node(cpu)); | |
044fa782 | 656 | if (!bpage) |
e4c2ce82 | 657 | goto free_pages; |
044fa782 | 658 | list_add(&bpage->list, &pages); |
7a8e76a3 SR |
659 | addr = __get_free_page(GFP_KERNEL); |
660 | if (!addr) | |
661 | goto free_pages; | |
044fa782 SR |
662 | bpage->page = (void *)addr; |
663 | rb_init_page(bpage->page); | |
7a8e76a3 SR |
664 | } |
665 | } | |
666 | ||
667 | for_each_buffer_cpu(buffer, cpu) { | |
668 | cpu_buffer = buffer->buffers[cpu]; | |
669 | rb_insert_pages(cpu_buffer, &pages, new_pages); | |
670 | } | |
671 | ||
3e89c7bb SR |
672 | if (RB_WARN_ON(buffer, !list_empty(&pages))) { |
673 | mutex_unlock(&buffer->mutex); | |
674 | return -1; | |
675 | } | |
7a8e76a3 SR |
676 | |
677 | out: | |
678 | buffer->pages = nr_pages; | |
679 | mutex_unlock(&buffer->mutex); | |
680 | ||
681 | return size; | |
682 | ||
683 | free_pages: | |
044fa782 SR |
684 | list_for_each_entry_safe(bpage, tmp, &pages, list) { |
685 | list_del_init(&bpage->list); | |
686 | free_buffer_page(bpage); | |
7a8e76a3 | 687 | } |
641d2f63 | 688 | mutex_unlock(&buffer->mutex); |
7a8e76a3 SR |
689 | return -ENOMEM; |
690 | } | |
c4f50183 | 691 | EXPORT_SYMBOL_GPL(ring_buffer_resize); |
7a8e76a3 | 692 | |
7a8e76a3 SR |
693 | static inline int rb_null_event(struct ring_buffer_event *event) |
694 | { | |
695 | return event->type == RINGBUF_TYPE_PADDING; | |
696 | } | |
697 | ||
8789a9e7 | 698 | static inline void * |
044fa782 | 699 | __rb_data_page_index(struct buffer_data_page *bpage, unsigned index) |
8789a9e7 | 700 | { |
044fa782 | 701 | return bpage->data + index; |
8789a9e7 SR |
702 | } |
703 | ||
044fa782 | 704 | static inline void *__rb_page_index(struct buffer_page *bpage, unsigned index) |
7a8e76a3 | 705 | { |
044fa782 | 706 | return bpage->page->data + index; |
7a8e76a3 SR |
707 | } |
708 | ||
709 | static inline struct ring_buffer_event * | |
d769041f | 710 | rb_reader_event(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 711 | { |
6f807acd SR |
712 | return __rb_page_index(cpu_buffer->reader_page, |
713 | cpu_buffer->reader_page->read); | |
714 | } | |
715 | ||
716 | static inline struct ring_buffer_event * | |
717 | rb_head_event(struct ring_buffer_per_cpu *cpu_buffer) | |
718 | { | |
719 | return __rb_page_index(cpu_buffer->head_page, | |
720 | cpu_buffer->head_page->read); | |
7a8e76a3 SR |
721 | } |
722 | ||
723 | static inline struct ring_buffer_event * | |
724 | rb_iter_head_event(struct ring_buffer_iter *iter) | |
725 | { | |
6f807acd | 726 | return __rb_page_index(iter->head_page, iter->head); |
7a8e76a3 SR |
727 | } |
728 | ||
bf41a158 SR |
729 | static inline unsigned rb_page_write(struct buffer_page *bpage) |
730 | { | |
731 | return local_read(&bpage->write); | |
732 | } | |
733 | ||
734 | static inline unsigned rb_page_commit(struct buffer_page *bpage) | |
735 | { | |
abc9b56d | 736 | return local_read(&bpage->page->commit); |
bf41a158 SR |
737 | } |
738 | ||
739 | /* Size is determined by what has been commited */ | |
740 | static inline unsigned rb_page_size(struct buffer_page *bpage) | |
741 | { | |
742 | return rb_page_commit(bpage); | |
743 | } | |
744 | ||
745 | static inline unsigned | |
746 | rb_commit_index(struct ring_buffer_per_cpu *cpu_buffer) | |
747 | { | |
748 | return rb_page_commit(cpu_buffer->commit_page); | |
749 | } | |
750 | ||
751 | static inline unsigned rb_head_size(struct ring_buffer_per_cpu *cpu_buffer) | |
752 | { | |
753 | return rb_page_commit(cpu_buffer->head_page); | |
754 | } | |
755 | ||
7a8e76a3 SR |
756 | /* |
757 | * When the tail hits the head and the buffer is in overwrite mode, | |
758 | * the head jumps to the next page and all content on the previous | |
759 | * page is discarded. But before doing so, we update the overrun | |
760 | * variable of the buffer. | |
761 | */ | |
762 | static void rb_update_overflow(struct ring_buffer_per_cpu *cpu_buffer) | |
763 | { | |
764 | struct ring_buffer_event *event; | |
765 | unsigned long head; | |
766 | ||
767 | for (head = 0; head < rb_head_size(cpu_buffer); | |
768 | head += rb_event_length(event)) { | |
769 | ||
6f807acd | 770 | event = __rb_page_index(cpu_buffer->head_page, head); |
3e89c7bb SR |
771 | if (RB_WARN_ON(cpu_buffer, rb_null_event(event))) |
772 | return; | |
7a8e76a3 SR |
773 | /* Only count data entries */ |
774 | if (event->type != RINGBUF_TYPE_DATA) | |
775 | continue; | |
776 | cpu_buffer->overrun++; | |
777 | cpu_buffer->entries--; | |
778 | } | |
779 | } | |
780 | ||
781 | static inline void rb_inc_page(struct ring_buffer_per_cpu *cpu_buffer, | |
044fa782 | 782 | struct buffer_page **bpage) |
7a8e76a3 | 783 | { |
044fa782 | 784 | struct list_head *p = (*bpage)->list.next; |
7a8e76a3 SR |
785 | |
786 | if (p == &cpu_buffer->pages) | |
787 | p = p->next; | |
788 | ||
044fa782 | 789 | *bpage = list_entry(p, struct buffer_page, list); |
7a8e76a3 SR |
790 | } |
791 | ||
bf41a158 SR |
792 | static inline unsigned |
793 | rb_event_index(struct ring_buffer_event *event) | |
794 | { | |
795 | unsigned long addr = (unsigned long)event; | |
796 | ||
797 | return (addr & ~PAGE_MASK) - (PAGE_SIZE - BUF_PAGE_SIZE); | |
798 | } | |
799 | ||
800 | static inline int | |
801 | rb_is_commit(struct ring_buffer_per_cpu *cpu_buffer, | |
802 | struct ring_buffer_event *event) | |
803 | { | |
804 | unsigned long addr = (unsigned long)event; | |
805 | unsigned long index; | |
806 | ||
807 | index = rb_event_index(event); | |
808 | addr &= PAGE_MASK; | |
809 | ||
810 | return cpu_buffer->commit_page->page == (void *)addr && | |
811 | rb_commit_index(cpu_buffer) == index; | |
812 | } | |
813 | ||
7a8e76a3 | 814 | static inline void |
bf41a158 SR |
815 | rb_set_commit_event(struct ring_buffer_per_cpu *cpu_buffer, |
816 | struct ring_buffer_event *event) | |
7a8e76a3 | 817 | { |
bf41a158 SR |
818 | unsigned long addr = (unsigned long)event; |
819 | unsigned long index; | |
820 | ||
821 | index = rb_event_index(event); | |
822 | addr &= PAGE_MASK; | |
823 | ||
824 | while (cpu_buffer->commit_page->page != (void *)addr) { | |
3e89c7bb SR |
825 | if (RB_WARN_ON(cpu_buffer, |
826 | cpu_buffer->commit_page == cpu_buffer->tail_page)) | |
827 | return; | |
abc9b56d | 828 | cpu_buffer->commit_page->page->commit = |
bf41a158 SR |
829 | cpu_buffer->commit_page->write; |
830 | rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); | |
abc9b56d SR |
831 | cpu_buffer->write_stamp = |
832 | cpu_buffer->commit_page->page->time_stamp; | |
bf41a158 SR |
833 | } |
834 | ||
835 | /* Now set the commit to the event's index */ | |
abc9b56d | 836 | local_set(&cpu_buffer->commit_page->page->commit, index); |
7a8e76a3 SR |
837 | } |
838 | ||
bf41a158 SR |
839 | static inline void |
840 | rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) | |
7a8e76a3 | 841 | { |
bf41a158 SR |
842 | /* |
843 | * We only race with interrupts and NMIs on this CPU. | |
844 | * If we own the commit event, then we can commit | |
845 | * all others that interrupted us, since the interruptions | |
846 | * are in stack format (they finish before they come | |
847 | * back to us). This allows us to do a simple loop to | |
848 | * assign the commit to the tail. | |
849 | */ | |
a8ccf1d6 | 850 | again: |
bf41a158 | 851 | while (cpu_buffer->commit_page != cpu_buffer->tail_page) { |
abc9b56d | 852 | cpu_buffer->commit_page->page->commit = |
bf41a158 SR |
853 | cpu_buffer->commit_page->write; |
854 | rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); | |
abc9b56d SR |
855 | cpu_buffer->write_stamp = |
856 | cpu_buffer->commit_page->page->time_stamp; | |
bf41a158 SR |
857 | /* add barrier to keep gcc from optimizing too much */ |
858 | barrier(); | |
859 | } | |
860 | while (rb_commit_index(cpu_buffer) != | |
861 | rb_page_write(cpu_buffer->commit_page)) { | |
abc9b56d | 862 | cpu_buffer->commit_page->page->commit = |
bf41a158 SR |
863 | cpu_buffer->commit_page->write; |
864 | barrier(); | |
865 | } | |
a8ccf1d6 SR |
866 | |
867 | /* again, keep gcc from optimizing */ | |
868 | barrier(); | |
869 | ||
870 | /* | |
871 | * If an interrupt came in just after the first while loop | |
872 | * and pushed the tail page forward, we will be left with | |
873 | * a dangling commit that will never go forward. | |
874 | */ | |
875 | if (unlikely(cpu_buffer->commit_page != cpu_buffer->tail_page)) | |
876 | goto again; | |
7a8e76a3 SR |
877 | } |
878 | ||
d769041f | 879 | static void rb_reset_reader_page(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 880 | { |
abc9b56d | 881 | cpu_buffer->read_stamp = cpu_buffer->reader_page->page->time_stamp; |
6f807acd | 882 | cpu_buffer->reader_page->read = 0; |
d769041f SR |
883 | } |
884 | ||
885 | static inline void rb_inc_iter(struct ring_buffer_iter *iter) | |
886 | { | |
887 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
888 | ||
889 | /* | |
890 | * The iterator could be on the reader page (it starts there). | |
891 | * But the head could have moved, since the reader was | |
892 | * found. Check for this case and assign the iterator | |
893 | * to the head page instead of next. | |
894 | */ | |
895 | if (iter->head_page == cpu_buffer->reader_page) | |
896 | iter->head_page = cpu_buffer->head_page; | |
897 | else | |
898 | rb_inc_page(cpu_buffer, &iter->head_page); | |
899 | ||
abc9b56d | 900 | iter->read_stamp = iter->head_page->page->time_stamp; |
7a8e76a3 SR |
901 | iter->head = 0; |
902 | } | |
903 | ||
904 | /** | |
905 | * ring_buffer_update_event - update event type and data | |
906 | * @event: the even to update | |
907 | * @type: the type of event | |
908 | * @length: the size of the event field in the ring buffer | |
909 | * | |
910 | * Update the type and data fields of the event. The length | |
911 | * is the actual size that is written to the ring buffer, | |
912 | * and with this, we can determine what to place into the | |
913 | * data field. | |
914 | */ | |
915 | static inline void | |
916 | rb_update_event(struct ring_buffer_event *event, | |
917 | unsigned type, unsigned length) | |
918 | { | |
919 | event->type = type; | |
920 | ||
921 | switch (type) { | |
922 | ||
923 | case RINGBUF_TYPE_PADDING: | |
924 | break; | |
925 | ||
926 | case RINGBUF_TYPE_TIME_EXTEND: | |
927 | event->len = | |
928 | (RB_LEN_TIME_EXTEND + (RB_ALIGNMENT-1)) | |
929 | >> RB_ALIGNMENT_SHIFT; | |
930 | break; | |
931 | ||
932 | case RINGBUF_TYPE_TIME_STAMP: | |
933 | event->len = | |
934 | (RB_LEN_TIME_STAMP + (RB_ALIGNMENT-1)) | |
935 | >> RB_ALIGNMENT_SHIFT; | |
936 | break; | |
937 | ||
938 | case RINGBUF_TYPE_DATA: | |
939 | length -= RB_EVNT_HDR_SIZE; | |
940 | if (length > RB_MAX_SMALL_DATA) { | |
941 | event->len = 0; | |
942 | event->array[0] = length; | |
943 | } else | |
944 | event->len = | |
945 | (length + (RB_ALIGNMENT-1)) | |
946 | >> RB_ALIGNMENT_SHIFT; | |
947 | break; | |
948 | default: | |
949 | BUG(); | |
950 | } | |
951 | } | |
952 | ||
953 | static inline unsigned rb_calculate_event_length(unsigned length) | |
954 | { | |
955 | struct ring_buffer_event event; /* Used only for sizeof array */ | |
956 | ||
957 | /* zero length can cause confusions */ | |
958 | if (!length) | |
959 | length = 1; | |
960 | ||
961 | if (length > RB_MAX_SMALL_DATA) | |
962 | length += sizeof(event.array[0]); | |
963 | ||
964 | length += RB_EVNT_HDR_SIZE; | |
965 | length = ALIGN(length, RB_ALIGNMENT); | |
966 | ||
967 | return length; | |
968 | } | |
969 | ||
970 | static struct ring_buffer_event * | |
971 | __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, | |
972 | unsigned type, unsigned long length, u64 *ts) | |
973 | { | |
98db8df7 | 974 | struct buffer_page *tail_page, *head_page, *reader_page, *commit_page; |
bf41a158 | 975 | unsigned long tail, write; |
7a8e76a3 SR |
976 | struct ring_buffer *buffer = cpu_buffer->buffer; |
977 | struct ring_buffer_event *event; | |
bf41a158 | 978 | unsigned long flags; |
7a8e76a3 | 979 | |
98db8df7 SR |
980 | commit_page = cpu_buffer->commit_page; |
981 | /* we just need to protect against interrupts */ | |
982 | barrier(); | |
7a8e76a3 | 983 | tail_page = cpu_buffer->tail_page; |
bf41a158 SR |
984 | write = local_add_return(length, &tail_page->write); |
985 | tail = write - length; | |
7a8e76a3 | 986 | |
bf41a158 SR |
987 | /* See if we shot pass the end of this buffer page */ |
988 | if (write > BUF_PAGE_SIZE) { | |
7a8e76a3 SR |
989 | struct buffer_page *next_page = tail_page; |
990 | ||
3e03fb7f SR |
991 | local_irq_save(flags); |
992 | __raw_spin_lock(&cpu_buffer->lock); | |
bf41a158 | 993 | |
7a8e76a3 SR |
994 | rb_inc_page(cpu_buffer, &next_page); |
995 | ||
d769041f SR |
996 | head_page = cpu_buffer->head_page; |
997 | reader_page = cpu_buffer->reader_page; | |
998 | ||
999 | /* we grabbed the lock before incrementing */ | |
3e89c7bb SR |
1000 | if (RB_WARN_ON(cpu_buffer, next_page == reader_page)) |
1001 | goto out_unlock; | |
bf41a158 SR |
1002 | |
1003 | /* | |
1004 | * If for some reason, we had an interrupt storm that made | |
1005 | * it all the way around the buffer, bail, and warn | |
1006 | * about it. | |
1007 | */ | |
98db8df7 | 1008 | if (unlikely(next_page == commit_page)) { |
bf41a158 SR |
1009 | WARN_ON_ONCE(1); |
1010 | goto out_unlock; | |
1011 | } | |
d769041f | 1012 | |
7a8e76a3 | 1013 | if (next_page == head_page) { |
d769041f | 1014 | if (!(buffer->flags & RB_FL_OVERWRITE)) { |
bf41a158 SR |
1015 | /* reset write */ |
1016 | if (tail <= BUF_PAGE_SIZE) | |
1017 | local_set(&tail_page->write, tail); | |
1018 | goto out_unlock; | |
d769041f | 1019 | } |
7a8e76a3 | 1020 | |
bf41a158 SR |
1021 | /* tail_page has not moved yet? */ |
1022 | if (tail_page == cpu_buffer->tail_page) { | |
1023 | /* count overflows */ | |
1024 | rb_update_overflow(cpu_buffer); | |
1025 | ||
1026 | rb_inc_page(cpu_buffer, &head_page); | |
1027 | cpu_buffer->head_page = head_page; | |
1028 | cpu_buffer->head_page->read = 0; | |
1029 | } | |
1030 | } | |
7a8e76a3 | 1031 | |
bf41a158 SR |
1032 | /* |
1033 | * If the tail page is still the same as what we think | |
1034 | * it is, then it is up to us to update the tail | |
1035 | * pointer. | |
1036 | */ | |
1037 | if (tail_page == cpu_buffer->tail_page) { | |
1038 | local_set(&next_page->write, 0); | |
abc9b56d | 1039 | local_set(&next_page->page->commit, 0); |
bf41a158 SR |
1040 | cpu_buffer->tail_page = next_page; |
1041 | ||
1042 | /* reread the time stamp */ | |
1043 | *ts = ring_buffer_time_stamp(cpu_buffer->cpu); | |
abc9b56d | 1044 | cpu_buffer->tail_page->page->time_stamp = *ts; |
7a8e76a3 SR |
1045 | } |
1046 | ||
bf41a158 SR |
1047 | /* |
1048 | * The actual tail page has moved forward. | |
1049 | */ | |
1050 | if (tail < BUF_PAGE_SIZE) { | |
1051 | /* Mark the rest of the page with padding */ | |
6f807acd | 1052 | event = __rb_page_index(tail_page, tail); |
7a8e76a3 SR |
1053 | event->type = RINGBUF_TYPE_PADDING; |
1054 | } | |
1055 | ||
bf41a158 SR |
1056 | if (tail <= BUF_PAGE_SIZE) |
1057 | /* Set the write back to the previous setting */ | |
1058 | local_set(&tail_page->write, tail); | |
1059 | ||
1060 | /* | |
1061 | * If this was a commit entry that failed, | |
1062 | * increment that too | |
1063 | */ | |
1064 | if (tail_page == cpu_buffer->commit_page && | |
1065 | tail == rb_commit_index(cpu_buffer)) { | |
1066 | rb_set_commit_to_write(cpu_buffer); | |
1067 | } | |
1068 | ||
3e03fb7f SR |
1069 | __raw_spin_unlock(&cpu_buffer->lock); |
1070 | local_irq_restore(flags); | |
bf41a158 SR |
1071 | |
1072 | /* fail and let the caller try again */ | |
1073 | return ERR_PTR(-EAGAIN); | |
7a8e76a3 SR |
1074 | } |
1075 | ||
bf41a158 SR |
1076 | /* We reserved something on the buffer */ |
1077 | ||
3e89c7bb SR |
1078 | if (RB_WARN_ON(cpu_buffer, write > BUF_PAGE_SIZE)) |
1079 | return NULL; | |
7a8e76a3 | 1080 | |
6f807acd | 1081 | event = __rb_page_index(tail_page, tail); |
7a8e76a3 SR |
1082 | rb_update_event(event, type, length); |
1083 | ||
bf41a158 SR |
1084 | /* |
1085 | * If this is a commit and the tail is zero, then update | |
1086 | * this page's time stamp. | |
1087 | */ | |
1088 | if (!tail && rb_is_commit(cpu_buffer, event)) | |
abc9b56d | 1089 | cpu_buffer->commit_page->page->time_stamp = *ts; |
bf41a158 | 1090 | |
7a8e76a3 | 1091 | return event; |
bf41a158 SR |
1092 | |
1093 | out_unlock: | |
3e03fb7f SR |
1094 | __raw_spin_unlock(&cpu_buffer->lock); |
1095 | local_irq_restore(flags); | |
bf41a158 | 1096 | return NULL; |
7a8e76a3 SR |
1097 | } |
1098 | ||
1099 | static int | |
1100 | rb_add_time_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
1101 | u64 *ts, u64 *delta) | |
1102 | { | |
1103 | struct ring_buffer_event *event; | |
1104 | static int once; | |
bf41a158 | 1105 | int ret; |
7a8e76a3 SR |
1106 | |
1107 | if (unlikely(*delta > (1ULL << 59) && !once++)) { | |
1108 | printk(KERN_WARNING "Delta way too big! %llu" | |
1109 | " ts=%llu write stamp = %llu\n", | |
e2862c94 SR |
1110 | (unsigned long long)*delta, |
1111 | (unsigned long long)*ts, | |
1112 | (unsigned long long)cpu_buffer->write_stamp); | |
7a8e76a3 SR |
1113 | WARN_ON(1); |
1114 | } | |
1115 | ||
1116 | /* | |
1117 | * The delta is too big, we to add a | |
1118 | * new timestamp. | |
1119 | */ | |
1120 | event = __rb_reserve_next(cpu_buffer, | |
1121 | RINGBUF_TYPE_TIME_EXTEND, | |
1122 | RB_LEN_TIME_EXTEND, | |
1123 | ts); | |
1124 | if (!event) | |
bf41a158 | 1125 | return -EBUSY; |
7a8e76a3 | 1126 | |
bf41a158 SR |
1127 | if (PTR_ERR(event) == -EAGAIN) |
1128 | return -EAGAIN; | |
1129 | ||
1130 | /* Only a commited time event can update the write stamp */ | |
1131 | if (rb_is_commit(cpu_buffer, event)) { | |
1132 | /* | |
1133 | * If this is the first on the page, then we need to | |
1134 | * update the page itself, and just put in a zero. | |
1135 | */ | |
1136 | if (rb_event_index(event)) { | |
1137 | event->time_delta = *delta & TS_MASK; | |
1138 | event->array[0] = *delta >> TS_SHIFT; | |
1139 | } else { | |
abc9b56d | 1140 | cpu_buffer->commit_page->page->time_stamp = *ts; |
bf41a158 SR |
1141 | event->time_delta = 0; |
1142 | event->array[0] = 0; | |
1143 | } | |
7a8e76a3 | 1144 | cpu_buffer->write_stamp = *ts; |
bf41a158 SR |
1145 | /* let the caller know this was the commit */ |
1146 | ret = 1; | |
1147 | } else { | |
1148 | /* Darn, this is just wasted space */ | |
1149 | event->time_delta = 0; | |
1150 | event->array[0] = 0; | |
1151 | ret = 0; | |
7a8e76a3 SR |
1152 | } |
1153 | ||
bf41a158 SR |
1154 | *delta = 0; |
1155 | ||
1156 | return ret; | |
7a8e76a3 SR |
1157 | } |
1158 | ||
1159 | static struct ring_buffer_event * | |
1160 | rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer, | |
1161 | unsigned type, unsigned long length) | |
1162 | { | |
1163 | struct ring_buffer_event *event; | |
1164 | u64 ts, delta; | |
bf41a158 | 1165 | int commit = 0; |
818e3dd3 | 1166 | int nr_loops = 0; |
7a8e76a3 | 1167 | |
bf41a158 | 1168 | again: |
818e3dd3 SR |
1169 | /* |
1170 | * We allow for interrupts to reenter here and do a trace. | |
1171 | * If one does, it will cause this original code to loop | |
1172 | * back here. Even with heavy interrupts happening, this | |
1173 | * should only happen a few times in a row. If this happens | |
1174 | * 1000 times in a row, there must be either an interrupt | |
1175 | * storm or we have something buggy. | |
1176 | * Bail! | |
1177 | */ | |
3e89c7bb | 1178 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000)) |
818e3dd3 | 1179 | return NULL; |
818e3dd3 | 1180 | |
7a8e76a3 SR |
1181 | ts = ring_buffer_time_stamp(cpu_buffer->cpu); |
1182 | ||
bf41a158 SR |
1183 | /* |
1184 | * Only the first commit can update the timestamp. | |
1185 | * Yes there is a race here. If an interrupt comes in | |
1186 | * just after the conditional and it traces too, then it | |
1187 | * will also check the deltas. More than one timestamp may | |
1188 | * also be made. But only the entry that did the actual | |
1189 | * commit will be something other than zero. | |
1190 | */ | |
1191 | if (cpu_buffer->tail_page == cpu_buffer->commit_page && | |
1192 | rb_page_write(cpu_buffer->tail_page) == | |
1193 | rb_commit_index(cpu_buffer)) { | |
1194 | ||
7a8e76a3 SR |
1195 | delta = ts - cpu_buffer->write_stamp; |
1196 | ||
bf41a158 SR |
1197 | /* make sure this delta is calculated here */ |
1198 | barrier(); | |
1199 | ||
1200 | /* Did the write stamp get updated already? */ | |
1201 | if (unlikely(ts < cpu_buffer->write_stamp)) | |
4143c5cb | 1202 | delta = 0; |
bf41a158 | 1203 | |
7a8e76a3 | 1204 | if (test_time_stamp(delta)) { |
7a8e76a3 | 1205 | |
bf41a158 SR |
1206 | commit = rb_add_time_stamp(cpu_buffer, &ts, &delta); |
1207 | ||
1208 | if (commit == -EBUSY) | |
7a8e76a3 | 1209 | return NULL; |
bf41a158 SR |
1210 | |
1211 | if (commit == -EAGAIN) | |
1212 | goto again; | |
1213 | ||
1214 | RB_WARN_ON(cpu_buffer, commit < 0); | |
7a8e76a3 | 1215 | } |
bf41a158 SR |
1216 | } else |
1217 | /* Non commits have zero deltas */ | |
7a8e76a3 | 1218 | delta = 0; |
7a8e76a3 SR |
1219 | |
1220 | event = __rb_reserve_next(cpu_buffer, type, length, &ts); | |
bf41a158 SR |
1221 | if (PTR_ERR(event) == -EAGAIN) |
1222 | goto again; | |
1223 | ||
1224 | if (!event) { | |
1225 | if (unlikely(commit)) | |
1226 | /* | |
1227 | * Ouch! We needed a timestamp and it was commited. But | |
1228 | * we didn't get our event reserved. | |
1229 | */ | |
1230 | rb_set_commit_to_write(cpu_buffer); | |
7a8e76a3 | 1231 | return NULL; |
bf41a158 | 1232 | } |
7a8e76a3 | 1233 | |
bf41a158 SR |
1234 | /* |
1235 | * If the timestamp was commited, make the commit our entry | |
1236 | * now so that we will update it when needed. | |
1237 | */ | |
1238 | if (commit) | |
1239 | rb_set_commit_event(cpu_buffer, event); | |
1240 | else if (!rb_is_commit(cpu_buffer, event)) | |
7a8e76a3 SR |
1241 | delta = 0; |
1242 | ||
1243 | event->time_delta = delta; | |
1244 | ||
1245 | return event; | |
1246 | } | |
1247 | ||
bf41a158 SR |
1248 | static DEFINE_PER_CPU(int, rb_need_resched); |
1249 | ||
7a8e76a3 SR |
1250 | /** |
1251 | * ring_buffer_lock_reserve - reserve a part of the buffer | |
1252 | * @buffer: the ring buffer to reserve from | |
1253 | * @length: the length of the data to reserve (excluding event header) | |
1254 | * @flags: a pointer to save the interrupt flags | |
1255 | * | |
1256 | * Returns a reseverd event on the ring buffer to copy directly to. | |
1257 | * The user of this interface will need to get the body to write into | |
1258 | * and can use the ring_buffer_event_data() interface. | |
1259 | * | |
1260 | * The length is the length of the data needed, not the event length | |
1261 | * which also includes the event header. | |
1262 | * | |
1263 | * Must be paired with ring_buffer_unlock_commit, unless NULL is returned. | |
1264 | * If NULL is returned, then nothing has been allocated or locked. | |
1265 | */ | |
1266 | struct ring_buffer_event * | |
1267 | ring_buffer_lock_reserve(struct ring_buffer *buffer, | |
1268 | unsigned long length, | |
1269 | unsigned long *flags) | |
1270 | { | |
1271 | struct ring_buffer_per_cpu *cpu_buffer; | |
1272 | struct ring_buffer_event *event; | |
bf41a158 | 1273 | int cpu, resched; |
7a8e76a3 | 1274 | |
033601a3 | 1275 | if (ring_buffer_flags != RB_BUFFERS_ON) |
a3583244 SR |
1276 | return NULL; |
1277 | ||
7a8e76a3 SR |
1278 | if (atomic_read(&buffer->record_disabled)) |
1279 | return NULL; | |
1280 | ||
bf41a158 | 1281 | /* If we are tracing schedule, we don't want to recurse */ |
182e9f5f | 1282 | resched = ftrace_preempt_disable(); |
bf41a158 | 1283 | |
7a8e76a3 SR |
1284 | cpu = raw_smp_processor_id(); |
1285 | ||
1286 | if (!cpu_isset(cpu, buffer->cpumask)) | |
d769041f | 1287 | goto out; |
7a8e76a3 SR |
1288 | |
1289 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 SR |
1290 | |
1291 | if (atomic_read(&cpu_buffer->record_disabled)) | |
d769041f | 1292 | goto out; |
7a8e76a3 SR |
1293 | |
1294 | length = rb_calculate_event_length(length); | |
1295 | if (length > BUF_PAGE_SIZE) | |
bf41a158 | 1296 | goto out; |
7a8e76a3 SR |
1297 | |
1298 | event = rb_reserve_next_event(cpu_buffer, RINGBUF_TYPE_DATA, length); | |
1299 | if (!event) | |
d769041f | 1300 | goto out; |
7a8e76a3 | 1301 | |
bf41a158 SR |
1302 | /* |
1303 | * Need to store resched state on this cpu. | |
1304 | * Only the first needs to. | |
1305 | */ | |
1306 | ||
1307 | if (preempt_count() == 1) | |
1308 | per_cpu(rb_need_resched, cpu) = resched; | |
1309 | ||
7a8e76a3 SR |
1310 | return event; |
1311 | ||
d769041f | 1312 | out: |
182e9f5f | 1313 | ftrace_preempt_enable(resched); |
7a8e76a3 SR |
1314 | return NULL; |
1315 | } | |
c4f50183 | 1316 | EXPORT_SYMBOL_GPL(ring_buffer_lock_reserve); |
7a8e76a3 SR |
1317 | |
1318 | static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, | |
1319 | struct ring_buffer_event *event) | |
1320 | { | |
7a8e76a3 | 1321 | cpu_buffer->entries++; |
bf41a158 SR |
1322 | |
1323 | /* Only process further if we own the commit */ | |
1324 | if (!rb_is_commit(cpu_buffer, event)) | |
1325 | return; | |
1326 | ||
1327 | cpu_buffer->write_stamp += event->time_delta; | |
1328 | ||
1329 | rb_set_commit_to_write(cpu_buffer); | |
7a8e76a3 SR |
1330 | } |
1331 | ||
1332 | /** | |
1333 | * ring_buffer_unlock_commit - commit a reserved | |
1334 | * @buffer: The buffer to commit to | |
1335 | * @event: The event pointer to commit. | |
1336 | * @flags: the interrupt flags received from ring_buffer_lock_reserve. | |
1337 | * | |
1338 | * This commits the data to the ring buffer, and releases any locks held. | |
1339 | * | |
1340 | * Must be paired with ring_buffer_lock_reserve. | |
1341 | */ | |
1342 | int ring_buffer_unlock_commit(struct ring_buffer *buffer, | |
1343 | struct ring_buffer_event *event, | |
1344 | unsigned long flags) | |
1345 | { | |
1346 | struct ring_buffer_per_cpu *cpu_buffer; | |
1347 | int cpu = raw_smp_processor_id(); | |
1348 | ||
1349 | cpu_buffer = buffer->buffers[cpu]; | |
1350 | ||
7a8e76a3 SR |
1351 | rb_commit(cpu_buffer, event); |
1352 | ||
bf41a158 SR |
1353 | /* |
1354 | * Only the last preempt count needs to restore preemption. | |
1355 | */ | |
182e9f5f SR |
1356 | if (preempt_count() == 1) |
1357 | ftrace_preempt_enable(per_cpu(rb_need_resched, cpu)); | |
1358 | else | |
bf41a158 | 1359 | preempt_enable_no_resched_notrace(); |
7a8e76a3 SR |
1360 | |
1361 | return 0; | |
1362 | } | |
c4f50183 | 1363 | EXPORT_SYMBOL_GPL(ring_buffer_unlock_commit); |
7a8e76a3 SR |
1364 | |
1365 | /** | |
1366 | * ring_buffer_write - write data to the buffer without reserving | |
1367 | * @buffer: The ring buffer to write to. | |
1368 | * @length: The length of the data being written (excluding the event header) | |
1369 | * @data: The data to write to the buffer. | |
1370 | * | |
1371 | * This is like ring_buffer_lock_reserve and ring_buffer_unlock_commit as | |
1372 | * one function. If you already have the data to write to the buffer, it | |
1373 | * may be easier to simply call this function. | |
1374 | * | |
1375 | * Note, like ring_buffer_lock_reserve, the length is the length of the data | |
1376 | * and not the length of the event which would hold the header. | |
1377 | */ | |
1378 | int ring_buffer_write(struct ring_buffer *buffer, | |
1379 | unsigned long length, | |
1380 | void *data) | |
1381 | { | |
1382 | struct ring_buffer_per_cpu *cpu_buffer; | |
1383 | struct ring_buffer_event *event; | |
bf41a158 | 1384 | unsigned long event_length; |
7a8e76a3 SR |
1385 | void *body; |
1386 | int ret = -EBUSY; | |
bf41a158 | 1387 | int cpu, resched; |
7a8e76a3 | 1388 | |
033601a3 | 1389 | if (ring_buffer_flags != RB_BUFFERS_ON) |
a3583244 SR |
1390 | return -EBUSY; |
1391 | ||
7a8e76a3 SR |
1392 | if (atomic_read(&buffer->record_disabled)) |
1393 | return -EBUSY; | |
1394 | ||
182e9f5f | 1395 | resched = ftrace_preempt_disable(); |
bf41a158 | 1396 | |
7a8e76a3 SR |
1397 | cpu = raw_smp_processor_id(); |
1398 | ||
1399 | if (!cpu_isset(cpu, buffer->cpumask)) | |
d769041f | 1400 | goto out; |
7a8e76a3 SR |
1401 | |
1402 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 SR |
1403 | |
1404 | if (atomic_read(&cpu_buffer->record_disabled)) | |
1405 | goto out; | |
1406 | ||
1407 | event_length = rb_calculate_event_length(length); | |
1408 | event = rb_reserve_next_event(cpu_buffer, | |
1409 | RINGBUF_TYPE_DATA, event_length); | |
1410 | if (!event) | |
1411 | goto out; | |
1412 | ||
1413 | body = rb_event_data(event); | |
1414 | ||
1415 | memcpy(body, data, length); | |
1416 | ||
1417 | rb_commit(cpu_buffer, event); | |
1418 | ||
1419 | ret = 0; | |
1420 | out: | |
182e9f5f | 1421 | ftrace_preempt_enable(resched); |
7a8e76a3 SR |
1422 | |
1423 | return ret; | |
1424 | } | |
c4f50183 | 1425 | EXPORT_SYMBOL_GPL(ring_buffer_write); |
7a8e76a3 | 1426 | |
bf41a158 SR |
1427 | static inline int rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) |
1428 | { | |
1429 | struct buffer_page *reader = cpu_buffer->reader_page; | |
1430 | struct buffer_page *head = cpu_buffer->head_page; | |
1431 | struct buffer_page *commit = cpu_buffer->commit_page; | |
1432 | ||
1433 | return reader->read == rb_page_commit(reader) && | |
1434 | (commit == reader || | |
1435 | (commit == head && | |
1436 | head->read == rb_page_commit(commit))); | |
1437 | } | |
1438 | ||
7a8e76a3 SR |
1439 | /** |
1440 | * ring_buffer_record_disable - stop all writes into the buffer | |
1441 | * @buffer: The ring buffer to stop writes to. | |
1442 | * | |
1443 | * This prevents all writes to the buffer. Any attempt to write | |
1444 | * to the buffer after this will fail and return NULL. | |
1445 | * | |
1446 | * The caller should call synchronize_sched() after this. | |
1447 | */ | |
1448 | void ring_buffer_record_disable(struct ring_buffer *buffer) | |
1449 | { | |
1450 | atomic_inc(&buffer->record_disabled); | |
1451 | } | |
c4f50183 | 1452 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable); |
7a8e76a3 SR |
1453 | |
1454 | /** | |
1455 | * ring_buffer_record_enable - enable writes to the buffer | |
1456 | * @buffer: The ring buffer to enable writes | |
1457 | * | |
1458 | * Note, multiple disables will need the same number of enables | |
1459 | * to truely enable the writing (much like preempt_disable). | |
1460 | */ | |
1461 | void ring_buffer_record_enable(struct ring_buffer *buffer) | |
1462 | { | |
1463 | atomic_dec(&buffer->record_disabled); | |
1464 | } | |
c4f50183 | 1465 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable); |
7a8e76a3 SR |
1466 | |
1467 | /** | |
1468 | * ring_buffer_record_disable_cpu - stop all writes into the cpu_buffer | |
1469 | * @buffer: The ring buffer to stop writes to. | |
1470 | * @cpu: The CPU buffer to stop | |
1471 | * | |
1472 | * This prevents all writes to the buffer. Any attempt to write | |
1473 | * to the buffer after this will fail and return NULL. | |
1474 | * | |
1475 | * The caller should call synchronize_sched() after this. | |
1476 | */ | |
1477 | void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu) | |
1478 | { | |
1479 | struct ring_buffer_per_cpu *cpu_buffer; | |
1480 | ||
1481 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1482 | return; | |
1483 | ||
1484 | cpu_buffer = buffer->buffers[cpu]; | |
1485 | atomic_inc(&cpu_buffer->record_disabled); | |
1486 | } | |
c4f50183 | 1487 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable_cpu); |
7a8e76a3 SR |
1488 | |
1489 | /** | |
1490 | * ring_buffer_record_enable_cpu - enable writes to the buffer | |
1491 | * @buffer: The ring buffer to enable writes | |
1492 | * @cpu: The CPU to enable. | |
1493 | * | |
1494 | * Note, multiple disables will need the same number of enables | |
1495 | * to truely enable the writing (much like preempt_disable). | |
1496 | */ | |
1497 | void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu) | |
1498 | { | |
1499 | struct ring_buffer_per_cpu *cpu_buffer; | |
1500 | ||
1501 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1502 | return; | |
1503 | ||
1504 | cpu_buffer = buffer->buffers[cpu]; | |
1505 | atomic_dec(&cpu_buffer->record_disabled); | |
1506 | } | |
c4f50183 | 1507 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu); |
7a8e76a3 SR |
1508 | |
1509 | /** | |
1510 | * ring_buffer_entries_cpu - get the number of entries in a cpu buffer | |
1511 | * @buffer: The ring buffer | |
1512 | * @cpu: The per CPU buffer to get the entries from. | |
1513 | */ | |
1514 | unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu) | |
1515 | { | |
1516 | struct ring_buffer_per_cpu *cpu_buffer; | |
1517 | ||
1518 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1519 | return 0; | |
1520 | ||
1521 | cpu_buffer = buffer->buffers[cpu]; | |
1522 | return cpu_buffer->entries; | |
1523 | } | |
c4f50183 | 1524 | EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu); |
7a8e76a3 SR |
1525 | |
1526 | /** | |
1527 | * ring_buffer_overrun_cpu - get the number of overruns in a cpu_buffer | |
1528 | * @buffer: The ring buffer | |
1529 | * @cpu: The per CPU buffer to get the number of overruns from | |
1530 | */ | |
1531 | unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu) | |
1532 | { | |
1533 | struct ring_buffer_per_cpu *cpu_buffer; | |
1534 | ||
1535 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1536 | return 0; | |
1537 | ||
1538 | cpu_buffer = buffer->buffers[cpu]; | |
1539 | return cpu_buffer->overrun; | |
1540 | } | |
c4f50183 | 1541 | EXPORT_SYMBOL_GPL(ring_buffer_overrun_cpu); |
7a8e76a3 SR |
1542 | |
1543 | /** | |
1544 | * ring_buffer_entries - get the number of entries in a buffer | |
1545 | * @buffer: The ring buffer | |
1546 | * | |
1547 | * Returns the total number of entries in the ring buffer | |
1548 | * (all CPU entries) | |
1549 | */ | |
1550 | unsigned long ring_buffer_entries(struct ring_buffer *buffer) | |
1551 | { | |
1552 | struct ring_buffer_per_cpu *cpu_buffer; | |
1553 | unsigned long entries = 0; | |
1554 | int cpu; | |
1555 | ||
1556 | /* if you care about this being correct, lock the buffer */ | |
1557 | for_each_buffer_cpu(buffer, cpu) { | |
1558 | cpu_buffer = buffer->buffers[cpu]; | |
1559 | entries += cpu_buffer->entries; | |
1560 | } | |
1561 | ||
1562 | return entries; | |
1563 | } | |
c4f50183 | 1564 | EXPORT_SYMBOL_GPL(ring_buffer_entries); |
7a8e76a3 SR |
1565 | |
1566 | /** | |
1567 | * ring_buffer_overrun_cpu - get the number of overruns in buffer | |
1568 | * @buffer: The ring buffer | |
1569 | * | |
1570 | * Returns the total number of overruns in the ring buffer | |
1571 | * (all CPU entries) | |
1572 | */ | |
1573 | unsigned long ring_buffer_overruns(struct ring_buffer *buffer) | |
1574 | { | |
1575 | struct ring_buffer_per_cpu *cpu_buffer; | |
1576 | unsigned long overruns = 0; | |
1577 | int cpu; | |
1578 | ||
1579 | /* if you care about this being correct, lock the buffer */ | |
1580 | for_each_buffer_cpu(buffer, cpu) { | |
1581 | cpu_buffer = buffer->buffers[cpu]; | |
1582 | overruns += cpu_buffer->overrun; | |
1583 | } | |
1584 | ||
1585 | return overruns; | |
1586 | } | |
c4f50183 | 1587 | EXPORT_SYMBOL_GPL(ring_buffer_overruns); |
7a8e76a3 | 1588 | |
642edba5 | 1589 | static void rb_iter_reset(struct ring_buffer_iter *iter) |
7a8e76a3 SR |
1590 | { |
1591 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
1592 | ||
d769041f SR |
1593 | /* Iterator usage is expected to have record disabled */ |
1594 | if (list_empty(&cpu_buffer->reader_page->list)) { | |
1595 | iter->head_page = cpu_buffer->head_page; | |
6f807acd | 1596 | iter->head = cpu_buffer->head_page->read; |
d769041f SR |
1597 | } else { |
1598 | iter->head_page = cpu_buffer->reader_page; | |
6f807acd | 1599 | iter->head = cpu_buffer->reader_page->read; |
d769041f SR |
1600 | } |
1601 | if (iter->head) | |
1602 | iter->read_stamp = cpu_buffer->read_stamp; | |
1603 | else | |
abc9b56d | 1604 | iter->read_stamp = iter->head_page->page->time_stamp; |
642edba5 | 1605 | } |
f83c9d0f | 1606 | |
642edba5 SR |
1607 | /** |
1608 | * ring_buffer_iter_reset - reset an iterator | |
1609 | * @iter: The iterator to reset | |
1610 | * | |
1611 | * Resets the iterator, so that it will start from the beginning | |
1612 | * again. | |
1613 | */ | |
1614 | void ring_buffer_iter_reset(struct ring_buffer_iter *iter) | |
1615 | { | |
1616 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
1617 | unsigned long flags; | |
1618 | ||
1619 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
1620 | rb_iter_reset(iter); | |
f83c9d0f | 1621 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
7a8e76a3 | 1622 | } |
c4f50183 | 1623 | EXPORT_SYMBOL_GPL(ring_buffer_iter_reset); |
7a8e76a3 SR |
1624 | |
1625 | /** | |
1626 | * ring_buffer_iter_empty - check if an iterator has no more to read | |
1627 | * @iter: The iterator to check | |
1628 | */ | |
1629 | int ring_buffer_iter_empty(struct ring_buffer_iter *iter) | |
1630 | { | |
1631 | struct ring_buffer_per_cpu *cpu_buffer; | |
1632 | ||
1633 | cpu_buffer = iter->cpu_buffer; | |
1634 | ||
bf41a158 SR |
1635 | return iter->head_page == cpu_buffer->commit_page && |
1636 | iter->head == rb_commit_index(cpu_buffer); | |
7a8e76a3 | 1637 | } |
c4f50183 | 1638 | EXPORT_SYMBOL_GPL(ring_buffer_iter_empty); |
7a8e76a3 SR |
1639 | |
1640 | static void | |
1641 | rb_update_read_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
1642 | struct ring_buffer_event *event) | |
1643 | { | |
1644 | u64 delta; | |
1645 | ||
1646 | switch (event->type) { | |
1647 | case RINGBUF_TYPE_PADDING: | |
1648 | return; | |
1649 | ||
1650 | case RINGBUF_TYPE_TIME_EXTEND: | |
1651 | delta = event->array[0]; | |
1652 | delta <<= TS_SHIFT; | |
1653 | delta += event->time_delta; | |
1654 | cpu_buffer->read_stamp += delta; | |
1655 | return; | |
1656 | ||
1657 | case RINGBUF_TYPE_TIME_STAMP: | |
1658 | /* FIXME: not implemented */ | |
1659 | return; | |
1660 | ||
1661 | case RINGBUF_TYPE_DATA: | |
1662 | cpu_buffer->read_stamp += event->time_delta; | |
1663 | return; | |
1664 | ||
1665 | default: | |
1666 | BUG(); | |
1667 | } | |
1668 | return; | |
1669 | } | |
1670 | ||
1671 | static void | |
1672 | rb_update_iter_read_stamp(struct ring_buffer_iter *iter, | |
1673 | struct ring_buffer_event *event) | |
1674 | { | |
1675 | u64 delta; | |
1676 | ||
1677 | switch (event->type) { | |
1678 | case RINGBUF_TYPE_PADDING: | |
1679 | return; | |
1680 | ||
1681 | case RINGBUF_TYPE_TIME_EXTEND: | |
1682 | delta = event->array[0]; | |
1683 | delta <<= TS_SHIFT; | |
1684 | delta += event->time_delta; | |
1685 | iter->read_stamp += delta; | |
1686 | return; | |
1687 | ||
1688 | case RINGBUF_TYPE_TIME_STAMP: | |
1689 | /* FIXME: not implemented */ | |
1690 | return; | |
1691 | ||
1692 | case RINGBUF_TYPE_DATA: | |
1693 | iter->read_stamp += event->time_delta; | |
1694 | return; | |
1695 | ||
1696 | default: | |
1697 | BUG(); | |
1698 | } | |
1699 | return; | |
1700 | } | |
1701 | ||
d769041f SR |
1702 | static struct buffer_page * |
1703 | rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) | |
7a8e76a3 | 1704 | { |
d769041f SR |
1705 | struct buffer_page *reader = NULL; |
1706 | unsigned long flags; | |
818e3dd3 | 1707 | int nr_loops = 0; |
d769041f | 1708 | |
3e03fb7f SR |
1709 | local_irq_save(flags); |
1710 | __raw_spin_lock(&cpu_buffer->lock); | |
d769041f SR |
1711 | |
1712 | again: | |
818e3dd3 SR |
1713 | /* |
1714 | * This should normally only loop twice. But because the | |
1715 | * start of the reader inserts an empty page, it causes | |
1716 | * a case where we will loop three times. There should be no | |
1717 | * reason to loop four times (that I know of). | |
1718 | */ | |
3e89c7bb | 1719 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 3)) { |
818e3dd3 SR |
1720 | reader = NULL; |
1721 | goto out; | |
1722 | } | |
1723 | ||
d769041f SR |
1724 | reader = cpu_buffer->reader_page; |
1725 | ||
1726 | /* If there's more to read, return this page */ | |
bf41a158 | 1727 | if (cpu_buffer->reader_page->read < rb_page_size(reader)) |
d769041f SR |
1728 | goto out; |
1729 | ||
1730 | /* Never should we have an index greater than the size */ | |
3e89c7bb SR |
1731 | if (RB_WARN_ON(cpu_buffer, |
1732 | cpu_buffer->reader_page->read > rb_page_size(reader))) | |
1733 | goto out; | |
d769041f SR |
1734 | |
1735 | /* check if we caught up to the tail */ | |
1736 | reader = NULL; | |
bf41a158 | 1737 | if (cpu_buffer->commit_page == cpu_buffer->reader_page) |
d769041f | 1738 | goto out; |
7a8e76a3 SR |
1739 | |
1740 | /* | |
d769041f SR |
1741 | * Splice the empty reader page into the list around the head. |
1742 | * Reset the reader page to size zero. | |
7a8e76a3 | 1743 | */ |
7a8e76a3 | 1744 | |
d769041f SR |
1745 | reader = cpu_buffer->head_page; |
1746 | cpu_buffer->reader_page->list.next = reader->list.next; | |
1747 | cpu_buffer->reader_page->list.prev = reader->list.prev; | |
bf41a158 SR |
1748 | |
1749 | local_set(&cpu_buffer->reader_page->write, 0); | |
abc9b56d | 1750 | local_set(&cpu_buffer->reader_page->page->commit, 0); |
7a8e76a3 | 1751 | |
d769041f SR |
1752 | /* Make the reader page now replace the head */ |
1753 | reader->list.prev->next = &cpu_buffer->reader_page->list; | |
1754 | reader->list.next->prev = &cpu_buffer->reader_page->list; | |
7a8e76a3 SR |
1755 | |
1756 | /* | |
d769041f SR |
1757 | * If the tail is on the reader, then we must set the head |
1758 | * to the inserted page, otherwise we set it one before. | |
7a8e76a3 | 1759 | */ |
d769041f | 1760 | cpu_buffer->head_page = cpu_buffer->reader_page; |
7a8e76a3 | 1761 | |
bf41a158 | 1762 | if (cpu_buffer->commit_page != reader) |
d769041f SR |
1763 | rb_inc_page(cpu_buffer, &cpu_buffer->head_page); |
1764 | ||
1765 | /* Finally update the reader page to the new head */ | |
1766 | cpu_buffer->reader_page = reader; | |
1767 | rb_reset_reader_page(cpu_buffer); | |
1768 | ||
1769 | goto again; | |
1770 | ||
1771 | out: | |
3e03fb7f SR |
1772 | __raw_spin_unlock(&cpu_buffer->lock); |
1773 | local_irq_restore(flags); | |
d769041f SR |
1774 | |
1775 | return reader; | |
1776 | } | |
1777 | ||
1778 | static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer) | |
1779 | { | |
1780 | struct ring_buffer_event *event; | |
1781 | struct buffer_page *reader; | |
1782 | unsigned length; | |
1783 | ||
1784 | reader = rb_get_reader_page(cpu_buffer); | |
7a8e76a3 | 1785 | |
d769041f | 1786 | /* This function should not be called when buffer is empty */ |
3e89c7bb SR |
1787 | if (RB_WARN_ON(cpu_buffer, !reader)) |
1788 | return; | |
7a8e76a3 | 1789 | |
d769041f SR |
1790 | event = rb_reader_event(cpu_buffer); |
1791 | ||
1792 | if (event->type == RINGBUF_TYPE_DATA) | |
1793 | cpu_buffer->entries--; | |
1794 | ||
1795 | rb_update_read_stamp(cpu_buffer, event); | |
1796 | ||
1797 | length = rb_event_length(event); | |
6f807acd | 1798 | cpu_buffer->reader_page->read += length; |
7a8e76a3 SR |
1799 | } |
1800 | ||
1801 | static void rb_advance_iter(struct ring_buffer_iter *iter) | |
1802 | { | |
1803 | struct ring_buffer *buffer; | |
1804 | struct ring_buffer_per_cpu *cpu_buffer; | |
1805 | struct ring_buffer_event *event; | |
1806 | unsigned length; | |
1807 | ||
1808 | cpu_buffer = iter->cpu_buffer; | |
1809 | buffer = cpu_buffer->buffer; | |
1810 | ||
1811 | /* | |
1812 | * Check if we are at the end of the buffer. | |
1813 | */ | |
bf41a158 | 1814 | if (iter->head >= rb_page_size(iter->head_page)) { |
3e89c7bb SR |
1815 | if (RB_WARN_ON(buffer, |
1816 | iter->head_page == cpu_buffer->commit_page)) | |
1817 | return; | |
d769041f | 1818 | rb_inc_iter(iter); |
7a8e76a3 SR |
1819 | return; |
1820 | } | |
1821 | ||
1822 | event = rb_iter_head_event(iter); | |
1823 | ||
1824 | length = rb_event_length(event); | |
1825 | ||
1826 | /* | |
1827 | * This should not be called to advance the header if we are | |
1828 | * at the tail of the buffer. | |
1829 | */ | |
3e89c7bb | 1830 | if (RB_WARN_ON(cpu_buffer, |
f536aafc | 1831 | (iter->head_page == cpu_buffer->commit_page) && |
3e89c7bb SR |
1832 | (iter->head + length > rb_commit_index(cpu_buffer)))) |
1833 | return; | |
7a8e76a3 SR |
1834 | |
1835 | rb_update_iter_read_stamp(iter, event); | |
1836 | ||
1837 | iter->head += length; | |
1838 | ||
1839 | /* check for end of page padding */ | |
bf41a158 SR |
1840 | if ((iter->head >= rb_page_size(iter->head_page)) && |
1841 | (iter->head_page != cpu_buffer->commit_page)) | |
7a8e76a3 SR |
1842 | rb_advance_iter(iter); |
1843 | } | |
1844 | ||
f83c9d0f SR |
1845 | static struct ring_buffer_event * |
1846 | rb_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) | |
7a8e76a3 SR |
1847 | { |
1848 | struct ring_buffer_per_cpu *cpu_buffer; | |
1849 | struct ring_buffer_event *event; | |
d769041f | 1850 | struct buffer_page *reader; |
818e3dd3 | 1851 | int nr_loops = 0; |
7a8e76a3 SR |
1852 | |
1853 | if (!cpu_isset(cpu, buffer->cpumask)) | |
1854 | return NULL; | |
1855 | ||
1856 | cpu_buffer = buffer->buffers[cpu]; | |
1857 | ||
1858 | again: | |
818e3dd3 SR |
1859 | /* |
1860 | * We repeat when a timestamp is encountered. It is possible | |
1861 | * to get multiple timestamps from an interrupt entering just | |
1862 | * as one timestamp is about to be written. The max times | |
1863 | * that this can happen is the number of nested interrupts we | |
1864 | * can have. Nesting 10 deep of interrupts is clearly | |
1865 | * an anomaly. | |
1866 | */ | |
3e89c7bb | 1867 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 10)) |
818e3dd3 | 1868 | return NULL; |
818e3dd3 | 1869 | |
d769041f SR |
1870 | reader = rb_get_reader_page(cpu_buffer); |
1871 | if (!reader) | |
7a8e76a3 SR |
1872 | return NULL; |
1873 | ||
d769041f | 1874 | event = rb_reader_event(cpu_buffer); |
7a8e76a3 SR |
1875 | |
1876 | switch (event->type) { | |
1877 | case RINGBUF_TYPE_PADDING: | |
bf41a158 | 1878 | RB_WARN_ON(cpu_buffer, 1); |
d769041f SR |
1879 | rb_advance_reader(cpu_buffer); |
1880 | return NULL; | |
7a8e76a3 SR |
1881 | |
1882 | case RINGBUF_TYPE_TIME_EXTEND: | |
1883 | /* Internal data, OK to advance */ | |
d769041f | 1884 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
1885 | goto again; |
1886 | ||
1887 | case RINGBUF_TYPE_TIME_STAMP: | |
1888 | /* FIXME: not implemented */ | |
d769041f | 1889 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
1890 | goto again; |
1891 | ||
1892 | case RINGBUF_TYPE_DATA: | |
1893 | if (ts) { | |
1894 | *ts = cpu_buffer->read_stamp + event->time_delta; | |
1895 | ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts); | |
1896 | } | |
1897 | return event; | |
1898 | ||
1899 | default: | |
1900 | BUG(); | |
1901 | } | |
1902 | ||
1903 | return NULL; | |
1904 | } | |
c4f50183 | 1905 | EXPORT_SYMBOL_GPL(ring_buffer_peek); |
7a8e76a3 | 1906 | |
f83c9d0f SR |
1907 | static struct ring_buffer_event * |
1908 | rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) | |
7a8e76a3 SR |
1909 | { |
1910 | struct ring_buffer *buffer; | |
1911 | struct ring_buffer_per_cpu *cpu_buffer; | |
1912 | struct ring_buffer_event *event; | |
818e3dd3 | 1913 | int nr_loops = 0; |
7a8e76a3 SR |
1914 | |
1915 | if (ring_buffer_iter_empty(iter)) | |
1916 | return NULL; | |
1917 | ||
1918 | cpu_buffer = iter->cpu_buffer; | |
1919 | buffer = cpu_buffer->buffer; | |
1920 | ||
1921 | again: | |
818e3dd3 SR |
1922 | /* |
1923 | * We repeat when a timestamp is encountered. It is possible | |
1924 | * to get multiple timestamps from an interrupt entering just | |
1925 | * as one timestamp is about to be written. The max times | |
1926 | * that this can happen is the number of nested interrupts we | |
1927 | * can have. Nesting 10 deep of interrupts is clearly | |
1928 | * an anomaly. | |
1929 | */ | |
3e89c7bb | 1930 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 10)) |
818e3dd3 | 1931 | return NULL; |
818e3dd3 | 1932 | |
7a8e76a3 SR |
1933 | if (rb_per_cpu_empty(cpu_buffer)) |
1934 | return NULL; | |
1935 | ||
1936 | event = rb_iter_head_event(iter); | |
1937 | ||
1938 | switch (event->type) { | |
1939 | case RINGBUF_TYPE_PADDING: | |
d769041f | 1940 | rb_inc_iter(iter); |
7a8e76a3 SR |
1941 | goto again; |
1942 | ||
1943 | case RINGBUF_TYPE_TIME_EXTEND: | |
1944 | /* Internal data, OK to advance */ | |
1945 | rb_advance_iter(iter); | |
1946 | goto again; | |
1947 | ||
1948 | case RINGBUF_TYPE_TIME_STAMP: | |
1949 | /* FIXME: not implemented */ | |
1950 | rb_advance_iter(iter); | |
1951 | goto again; | |
1952 | ||
1953 | case RINGBUF_TYPE_DATA: | |
1954 | if (ts) { | |
1955 | *ts = iter->read_stamp + event->time_delta; | |
1956 | ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts); | |
1957 | } | |
1958 | return event; | |
1959 | ||
1960 | default: | |
1961 | BUG(); | |
1962 | } | |
1963 | ||
1964 | return NULL; | |
1965 | } | |
c4f50183 | 1966 | EXPORT_SYMBOL_GPL(ring_buffer_iter_peek); |
7a8e76a3 | 1967 | |
f83c9d0f SR |
1968 | /** |
1969 | * ring_buffer_peek - peek at the next event to be read | |
1970 | * @buffer: The ring buffer to read | |
1971 | * @cpu: The cpu to peak at | |
1972 | * @ts: The timestamp counter of this event. | |
1973 | * | |
1974 | * This will return the event that will be read next, but does | |
1975 | * not consume the data. | |
1976 | */ | |
1977 | struct ring_buffer_event * | |
1978 | ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) | |
1979 | { | |
1980 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
1981 | struct ring_buffer_event *event; | |
1982 | unsigned long flags; | |
1983 | ||
1984 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
1985 | event = rb_buffer_peek(buffer, cpu, ts); | |
1986 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
1987 | ||
1988 | return event; | |
1989 | } | |
1990 | ||
1991 | /** | |
1992 | * ring_buffer_iter_peek - peek at the next event to be read | |
1993 | * @iter: The ring buffer iterator | |
1994 | * @ts: The timestamp counter of this event. | |
1995 | * | |
1996 | * This will return the event that will be read next, but does | |
1997 | * not increment the iterator. | |
1998 | */ | |
1999 | struct ring_buffer_event * | |
2000 | ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) | |
2001 | { | |
2002 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
2003 | struct ring_buffer_event *event; | |
2004 | unsigned long flags; | |
2005 | ||
2006 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
2007 | event = rb_iter_peek(iter, ts); | |
2008 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
2009 | ||
2010 | return event; | |
2011 | } | |
2012 | ||
7a8e76a3 SR |
2013 | /** |
2014 | * ring_buffer_consume - return an event and consume it | |
2015 | * @buffer: The ring buffer to get the next event from | |
2016 | * | |
2017 | * Returns the next event in the ring buffer, and that event is consumed. | |
2018 | * Meaning, that sequential reads will keep returning a different event, | |
2019 | * and eventually empty the ring buffer if the producer is slower. | |
2020 | */ | |
2021 | struct ring_buffer_event * | |
2022 | ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts) | |
2023 | { | |
f83c9d0f | 2024 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; |
7a8e76a3 | 2025 | struct ring_buffer_event *event; |
f83c9d0f | 2026 | unsigned long flags; |
7a8e76a3 SR |
2027 | |
2028 | if (!cpu_isset(cpu, buffer->cpumask)) | |
2029 | return NULL; | |
2030 | ||
f83c9d0f SR |
2031 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
2032 | ||
2033 | event = rb_buffer_peek(buffer, cpu, ts); | |
7a8e76a3 | 2034 | if (!event) |
f83c9d0f | 2035 | goto out; |
7a8e76a3 | 2036 | |
d769041f | 2037 | rb_advance_reader(cpu_buffer); |
7a8e76a3 | 2038 | |
f83c9d0f SR |
2039 | out: |
2040 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
2041 | ||
7a8e76a3 SR |
2042 | return event; |
2043 | } | |
c4f50183 | 2044 | EXPORT_SYMBOL_GPL(ring_buffer_consume); |
7a8e76a3 SR |
2045 | |
2046 | /** | |
2047 | * ring_buffer_read_start - start a non consuming read of the buffer | |
2048 | * @buffer: The ring buffer to read from | |
2049 | * @cpu: The cpu buffer to iterate over | |
2050 | * | |
2051 | * This starts up an iteration through the buffer. It also disables | |
2052 | * the recording to the buffer until the reading is finished. | |
2053 | * This prevents the reading from being corrupted. This is not | |
2054 | * a consuming read, so a producer is not expected. | |
2055 | * | |
2056 | * Must be paired with ring_buffer_finish. | |
2057 | */ | |
2058 | struct ring_buffer_iter * | |
2059 | ring_buffer_read_start(struct ring_buffer *buffer, int cpu) | |
2060 | { | |
2061 | struct ring_buffer_per_cpu *cpu_buffer; | |
2062 | struct ring_buffer_iter *iter; | |
d769041f | 2063 | unsigned long flags; |
7a8e76a3 SR |
2064 | |
2065 | if (!cpu_isset(cpu, buffer->cpumask)) | |
2066 | return NULL; | |
2067 | ||
2068 | iter = kmalloc(sizeof(*iter), GFP_KERNEL); | |
2069 | if (!iter) | |
2070 | return NULL; | |
2071 | ||
2072 | cpu_buffer = buffer->buffers[cpu]; | |
2073 | ||
2074 | iter->cpu_buffer = cpu_buffer; | |
2075 | ||
2076 | atomic_inc(&cpu_buffer->record_disabled); | |
2077 | synchronize_sched(); | |
2078 | ||
f83c9d0f | 2079 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
3e03fb7f | 2080 | __raw_spin_lock(&cpu_buffer->lock); |
642edba5 | 2081 | rb_iter_reset(iter); |
3e03fb7f | 2082 | __raw_spin_unlock(&cpu_buffer->lock); |
f83c9d0f | 2083 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
7a8e76a3 SR |
2084 | |
2085 | return iter; | |
2086 | } | |
c4f50183 | 2087 | EXPORT_SYMBOL_GPL(ring_buffer_read_start); |
7a8e76a3 SR |
2088 | |
2089 | /** | |
2090 | * ring_buffer_finish - finish reading the iterator of the buffer | |
2091 | * @iter: The iterator retrieved by ring_buffer_start | |
2092 | * | |
2093 | * This re-enables the recording to the buffer, and frees the | |
2094 | * iterator. | |
2095 | */ | |
2096 | void | |
2097 | ring_buffer_read_finish(struct ring_buffer_iter *iter) | |
2098 | { | |
2099 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
2100 | ||
2101 | atomic_dec(&cpu_buffer->record_disabled); | |
2102 | kfree(iter); | |
2103 | } | |
c4f50183 | 2104 | EXPORT_SYMBOL_GPL(ring_buffer_read_finish); |
7a8e76a3 SR |
2105 | |
2106 | /** | |
2107 | * ring_buffer_read - read the next item in the ring buffer by the iterator | |
2108 | * @iter: The ring buffer iterator | |
2109 | * @ts: The time stamp of the event read. | |
2110 | * | |
2111 | * This reads the next event in the ring buffer and increments the iterator. | |
2112 | */ | |
2113 | struct ring_buffer_event * | |
2114 | ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) | |
2115 | { | |
2116 | struct ring_buffer_event *event; | |
f83c9d0f SR |
2117 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
2118 | unsigned long flags; | |
7a8e76a3 | 2119 | |
f83c9d0f SR |
2120 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
2121 | event = rb_iter_peek(iter, ts); | |
7a8e76a3 | 2122 | if (!event) |
f83c9d0f | 2123 | goto out; |
7a8e76a3 SR |
2124 | |
2125 | rb_advance_iter(iter); | |
f83c9d0f SR |
2126 | out: |
2127 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
7a8e76a3 SR |
2128 | |
2129 | return event; | |
2130 | } | |
c4f50183 | 2131 | EXPORT_SYMBOL_GPL(ring_buffer_read); |
7a8e76a3 SR |
2132 | |
2133 | /** | |
2134 | * ring_buffer_size - return the size of the ring buffer (in bytes) | |
2135 | * @buffer: The ring buffer. | |
2136 | */ | |
2137 | unsigned long ring_buffer_size(struct ring_buffer *buffer) | |
2138 | { | |
2139 | return BUF_PAGE_SIZE * buffer->pages; | |
2140 | } | |
c4f50183 | 2141 | EXPORT_SYMBOL_GPL(ring_buffer_size); |
7a8e76a3 SR |
2142 | |
2143 | static void | |
2144 | rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) | |
2145 | { | |
2146 | cpu_buffer->head_page | |
2147 | = list_entry(cpu_buffer->pages.next, struct buffer_page, list); | |
bf41a158 | 2148 | local_set(&cpu_buffer->head_page->write, 0); |
abc9b56d | 2149 | local_set(&cpu_buffer->head_page->page->commit, 0); |
d769041f | 2150 | |
6f807acd | 2151 | cpu_buffer->head_page->read = 0; |
bf41a158 SR |
2152 | |
2153 | cpu_buffer->tail_page = cpu_buffer->head_page; | |
2154 | cpu_buffer->commit_page = cpu_buffer->head_page; | |
2155 | ||
2156 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); | |
2157 | local_set(&cpu_buffer->reader_page->write, 0); | |
abc9b56d | 2158 | local_set(&cpu_buffer->reader_page->page->commit, 0); |
6f807acd | 2159 | cpu_buffer->reader_page->read = 0; |
7a8e76a3 | 2160 | |
7a8e76a3 SR |
2161 | cpu_buffer->overrun = 0; |
2162 | cpu_buffer->entries = 0; | |
2163 | } | |
2164 | ||
2165 | /** | |
2166 | * ring_buffer_reset_cpu - reset a ring buffer per CPU buffer | |
2167 | * @buffer: The ring buffer to reset a per cpu buffer of | |
2168 | * @cpu: The CPU buffer to be reset | |
2169 | */ | |
2170 | void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) | |
2171 | { | |
2172 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
2173 | unsigned long flags; | |
2174 | ||
2175 | if (!cpu_isset(cpu, buffer->cpumask)) | |
2176 | return; | |
2177 | ||
f83c9d0f SR |
2178 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
2179 | ||
3e03fb7f | 2180 | __raw_spin_lock(&cpu_buffer->lock); |
7a8e76a3 SR |
2181 | |
2182 | rb_reset_cpu(cpu_buffer); | |
2183 | ||
3e03fb7f | 2184 | __raw_spin_unlock(&cpu_buffer->lock); |
f83c9d0f SR |
2185 | |
2186 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
7a8e76a3 | 2187 | } |
c4f50183 | 2188 | EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); |
7a8e76a3 SR |
2189 | |
2190 | /** | |
2191 | * ring_buffer_reset - reset a ring buffer | |
2192 | * @buffer: The ring buffer to reset all cpu buffers | |
2193 | */ | |
2194 | void ring_buffer_reset(struct ring_buffer *buffer) | |
2195 | { | |
7a8e76a3 SR |
2196 | int cpu; |
2197 | ||
7a8e76a3 | 2198 | for_each_buffer_cpu(buffer, cpu) |
d769041f | 2199 | ring_buffer_reset_cpu(buffer, cpu); |
7a8e76a3 | 2200 | } |
c4f50183 | 2201 | EXPORT_SYMBOL_GPL(ring_buffer_reset); |
7a8e76a3 SR |
2202 | |
2203 | /** | |
2204 | * rind_buffer_empty - is the ring buffer empty? | |
2205 | * @buffer: The ring buffer to test | |
2206 | */ | |
2207 | int ring_buffer_empty(struct ring_buffer *buffer) | |
2208 | { | |
2209 | struct ring_buffer_per_cpu *cpu_buffer; | |
2210 | int cpu; | |
2211 | ||
2212 | /* yes this is racy, but if you don't like the race, lock the buffer */ | |
2213 | for_each_buffer_cpu(buffer, cpu) { | |
2214 | cpu_buffer = buffer->buffers[cpu]; | |
2215 | if (!rb_per_cpu_empty(cpu_buffer)) | |
2216 | return 0; | |
2217 | } | |
2218 | return 1; | |
2219 | } | |
c4f50183 | 2220 | EXPORT_SYMBOL_GPL(ring_buffer_empty); |
7a8e76a3 SR |
2221 | |
2222 | /** | |
2223 | * ring_buffer_empty_cpu - is a cpu buffer of a ring buffer empty? | |
2224 | * @buffer: The ring buffer | |
2225 | * @cpu: The CPU buffer to test | |
2226 | */ | |
2227 | int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) | |
2228 | { | |
2229 | struct ring_buffer_per_cpu *cpu_buffer; | |
2230 | ||
2231 | if (!cpu_isset(cpu, buffer->cpumask)) | |
2232 | return 1; | |
2233 | ||
2234 | cpu_buffer = buffer->buffers[cpu]; | |
2235 | return rb_per_cpu_empty(cpu_buffer); | |
2236 | } | |
c4f50183 | 2237 | EXPORT_SYMBOL_GPL(ring_buffer_empty_cpu); |
7a8e76a3 SR |
2238 | |
2239 | /** | |
2240 | * ring_buffer_swap_cpu - swap a CPU buffer between two ring buffers | |
2241 | * @buffer_a: One buffer to swap with | |
2242 | * @buffer_b: The other buffer to swap with | |
2243 | * | |
2244 | * This function is useful for tracers that want to take a "snapshot" | |
2245 | * of a CPU buffer and has another back up buffer lying around. | |
2246 | * it is expected that the tracer handles the cpu buffer not being | |
2247 | * used at the moment. | |
2248 | */ | |
2249 | int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, | |
2250 | struct ring_buffer *buffer_b, int cpu) | |
2251 | { | |
2252 | struct ring_buffer_per_cpu *cpu_buffer_a; | |
2253 | struct ring_buffer_per_cpu *cpu_buffer_b; | |
2254 | ||
2255 | if (!cpu_isset(cpu, buffer_a->cpumask) || | |
2256 | !cpu_isset(cpu, buffer_b->cpumask)) | |
2257 | return -EINVAL; | |
2258 | ||
2259 | /* At least make sure the two buffers are somewhat the same */ | |
6d102bc6 | 2260 | if (buffer_a->pages != buffer_b->pages) |
7a8e76a3 SR |
2261 | return -EINVAL; |
2262 | ||
2263 | cpu_buffer_a = buffer_a->buffers[cpu]; | |
2264 | cpu_buffer_b = buffer_b->buffers[cpu]; | |
2265 | ||
2266 | /* | |
2267 | * We can't do a synchronize_sched here because this | |
2268 | * function can be called in atomic context. | |
2269 | * Normally this will be called from the same CPU as cpu. | |
2270 | * If not it's up to the caller to protect this. | |
2271 | */ | |
2272 | atomic_inc(&cpu_buffer_a->record_disabled); | |
2273 | atomic_inc(&cpu_buffer_b->record_disabled); | |
2274 | ||
2275 | buffer_a->buffers[cpu] = cpu_buffer_b; | |
2276 | buffer_b->buffers[cpu] = cpu_buffer_a; | |
2277 | ||
2278 | cpu_buffer_b->buffer = buffer_a; | |
2279 | cpu_buffer_a->buffer = buffer_b; | |
2280 | ||
2281 | atomic_dec(&cpu_buffer_a->record_disabled); | |
2282 | atomic_dec(&cpu_buffer_b->record_disabled); | |
2283 | ||
2284 | return 0; | |
2285 | } | |
c4f50183 | 2286 | EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu); |
7a8e76a3 | 2287 | |
8789a9e7 | 2288 | static void rb_remove_entries(struct ring_buffer_per_cpu *cpu_buffer, |
044fa782 | 2289 | struct buffer_data_page *bpage) |
8789a9e7 SR |
2290 | { |
2291 | struct ring_buffer_event *event; | |
2292 | unsigned long head; | |
2293 | ||
2294 | __raw_spin_lock(&cpu_buffer->lock); | |
044fa782 | 2295 | for (head = 0; head < local_read(&bpage->commit); |
8789a9e7 SR |
2296 | head += rb_event_length(event)) { |
2297 | ||
044fa782 | 2298 | event = __rb_data_page_index(bpage, head); |
8789a9e7 SR |
2299 | if (RB_WARN_ON(cpu_buffer, rb_null_event(event))) |
2300 | return; | |
2301 | /* Only count data entries */ | |
2302 | if (event->type != RINGBUF_TYPE_DATA) | |
2303 | continue; | |
2304 | cpu_buffer->entries--; | |
2305 | } | |
2306 | __raw_spin_unlock(&cpu_buffer->lock); | |
2307 | } | |
2308 | ||
2309 | /** | |
2310 | * ring_buffer_alloc_read_page - allocate a page to read from buffer | |
2311 | * @buffer: the buffer to allocate for. | |
2312 | * | |
2313 | * This function is used in conjunction with ring_buffer_read_page. | |
2314 | * When reading a full page from the ring buffer, these functions | |
2315 | * can be used to speed up the process. The calling function should | |
2316 | * allocate a few pages first with this function. Then when it | |
2317 | * needs to get pages from the ring buffer, it passes the result | |
2318 | * of this function into ring_buffer_read_page, which will swap | |
2319 | * the page that was allocated, with the read page of the buffer. | |
2320 | * | |
2321 | * Returns: | |
2322 | * The page allocated, or NULL on error. | |
2323 | */ | |
2324 | void *ring_buffer_alloc_read_page(struct ring_buffer *buffer) | |
2325 | { | |
2326 | unsigned long addr; | |
044fa782 | 2327 | struct buffer_data_page *bpage; |
8789a9e7 SR |
2328 | |
2329 | addr = __get_free_page(GFP_KERNEL); | |
2330 | if (!addr) | |
2331 | return NULL; | |
2332 | ||
044fa782 | 2333 | bpage = (void *)addr; |
8789a9e7 | 2334 | |
044fa782 | 2335 | return bpage; |
8789a9e7 SR |
2336 | } |
2337 | ||
2338 | /** | |
2339 | * ring_buffer_free_read_page - free an allocated read page | |
2340 | * @buffer: the buffer the page was allocate for | |
2341 | * @data: the page to free | |
2342 | * | |
2343 | * Free a page allocated from ring_buffer_alloc_read_page. | |
2344 | */ | |
2345 | void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data) | |
2346 | { | |
2347 | free_page((unsigned long)data); | |
2348 | } | |
2349 | ||
2350 | /** | |
2351 | * ring_buffer_read_page - extract a page from the ring buffer | |
2352 | * @buffer: buffer to extract from | |
2353 | * @data_page: the page to use allocated from ring_buffer_alloc_read_page | |
2354 | * @cpu: the cpu of the buffer to extract | |
2355 | * @full: should the extraction only happen when the page is full. | |
2356 | * | |
2357 | * This function will pull out a page from the ring buffer and consume it. | |
2358 | * @data_page must be the address of the variable that was returned | |
2359 | * from ring_buffer_alloc_read_page. This is because the page might be used | |
2360 | * to swap with a page in the ring buffer. | |
2361 | * | |
2362 | * for example: | |
2363 | * rpage = ring_buffer_alloc_page(buffer); | |
2364 | * if (!rpage) | |
2365 | * return error; | |
2366 | * ret = ring_buffer_read_page(buffer, &rpage, cpu, 0); | |
2367 | * if (ret) | |
2368 | * process_page(rpage); | |
2369 | * | |
2370 | * When @full is set, the function will not return true unless | |
2371 | * the writer is off the reader page. | |
2372 | * | |
2373 | * Note: it is up to the calling functions to handle sleeps and wakeups. | |
2374 | * The ring buffer can be used anywhere in the kernel and can not | |
2375 | * blindly call wake_up. The layer that uses the ring buffer must be | |
2376 | * responsible for that. | |
2377 | * | |
2378 | * Returns: | |
2379 | * 1 if data has been transferred | |
2380 | * 0 if no data has been transferred. | |
2381 | */ | |
2382 | int ring_buffer_read_page(struct ring_buffer *buffer, | |
2383 | void **data_page, int cpu, int full) | |
2384 | { | |
2385 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
2386 | struct ring_buffer_event *event; | |
044fa782 | 2387 | struct buffer_data_page *bpage; |
8789a9e7 SR |
2388 | unsigned long flags; |
2389 | int ret = 0; | |
2390 | ||
2391 | if (!data_page) | |
2392 | return 0; | |
2393 | ||
044fa782 SR |
2394 | bpage = *data_page; |
2395 | if (!bpage) | |
8789a9e7 SR |
2396 | return 0; |
2397 | ||
2398 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
2399 | ||
2400 | /* | |
2401 | * rb_buffer_peek will get the next ring buffer if | |
2402 | * the current reader page is empty. | |
2403 | */ | |
2404 | event = rb_buffer_peek(buffer, cpu, NULL); | |
2405 | if (!event) | |
2406 | goto out; | |
2407 | ||
2408 | /* check for data */ | |
2409 | if (!local_read(&cpu_buffer->reader_page->page->commit)) | |
2410 | goto out; | |
2411 | /* | |
2412 | * If the writer is already off of the read page, then simply | |
2413 | * switch the read page with the given page. Otherwise | |
2414 | * we need to copy the data from the reader to the writer. | |
2415 | */ | |
2416 | if (cpu_buffer->reader_page == cpu_buffer->commit_page) { | |
2417 | unsigned int read = cpu_buffer->reader_page->read; | |
2418 | ||
2419 | if (full) | |
2420 | goto out; | |
2421 | /* The writer is still on the reader page, we must copy */ | |
044fa782 SR |
2422 | bpage = cpu_buffer->reader_page->page; |
2423 | memcpy(bpage->data, | |
8789a9e7 | 2424 | cpu_buffer->reader_page->page->data + read, |
044fa782 | 2425 | local_read(&bpage->commit) - read); |
8789a9e7 SR |
2426 | |
2427 | /* consume what was read */ | |
2428 | cpu_buffer->reader_page += read; | |
2429 | ||
2430 | } else { | |
2431 | /* swap the pages */ | |
044fa782 SR |
2432 | rb_init_page(bpage); |
2433 | bpage = cpu_buffer->reader_page->page; | |
8789a9e7 SR |
2434 | cpu_buffer->reader_page->page = *data_page; |
2435 | cpu_buffer->reader_page->read = 0; | |
044fa782 | 2436 | *data_page = bpage; |
8789a9e7 SR |
2437 | } |
2438 | ret = 1; | |
2439 | ||
2440 | /* update the entry counter */ | |
044fa782 | 2441 | rb_remove_entries(cpu_buffer, bpage); |
8789a9e7 SR |
2442 | out: |
2443 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
2444 | ||
2445 | return ret; | |
2446 | } | |
2447 | ||
a3583244 SR |
2448 | static ssize_t |
2449 | rb_simple_read(struct file *filp, char __user *ubuf, | |
2450 | size_t cnt, loff_t *ppos) | |
2451 | { | |
033601a3 | 2452 | long *p = filp->private_data; |
a3583244 SR |
2453 | char buf[64]; |
2454 | int r; | |
2455 | ||
033601a3 SR |
2456 | if (test_bit(RB_BUFFERS_DISABLED_BIT, p)) |
2457 | r = sprintf(buf, "permanently disabled\n"); | |
2458 | else | |
2459 | r = sprintf(buf, "%d\n", test_bit(RB_BUFFERS_ON_BIT, p)); | |
a3583244 SR |
2460 | |
2461 | return simple_read_from_buffer(ubuf, cnt, ppos, buf, r); | |
2462 | } | |
2463 | ||
2464 | static ssize_t | |
2465 | rb_simple_write(struct file *filp, const char __user *ubuf, | |
2466 | size_t cnt, loff_t *ppos) | |
2467 | { | |
033601a3 | 2468 | long *p = filp->private_data; |
a3583244 SR |
2469 | char buf[64]; |
2470 | long val; | |
2471 | int ret; | |
2472 | ||
2473 | if (cnt >= sizeof(buf)) | |
2474 | return -EINVAL; | |
2475 | ||
2476 | if (copy_from_user(&buf, ubuf, cnt)) | |
2477 | return -EFAULT; | |
2478 | ||
2479 | buf[cnt] = 0; | |
2480 | ||
2481 | ret = strict_strtoul(buf, 10, &val); | |
2482 | if (ret < 0) | |
2483 | return ret; | |
2484 | ||
033601a3 SR |
2485 | if (val) |
2486 | set_bit(RB_BUFFERS_ON_BIT, p); | |
2487 | else | |
2488 | clear_bit(RB_BUFFERS_ON_BIT, p); | |
a3583244 SR |
2489 | |
2490 | (*ppos)++; | |
2491 | ||
2492 | return cnt; | |
2493 | } | |
2494 | ||
2495 | static struct file_operations rb_simple_fops = { | |
2496 | .open = tracing_open_generic, | |
2497 | .read = rb_simple_read, | |
2498 | .write = rb_simple_write, | |
2499 | }; | |
2500 | ||
2501 | ||
2502 | static __init int rb_init_debugfs(void) | |
2503 | { | |
2504 | struct dentry *d_tracer; | |
2505 | struct dentry *entry; | |
2506 | ||
2507 | d_tracer = tracing_init_dentry(); | |
2508 | ||
2509 | entry = debugfs_create_file("tracing_on", 0644, d_tracer, | |
033601a3 | 2510 | &ring_buffer_flags, &rb_simple_fops); |
a3583244 SR |
2511 | if (!entry) |
2512 | pr_warning("Could not create debugfs 'tracing_on' entry\n"); | |
2513 | ||
2514 | return 0; | |
2515 | } | |
2516 | ||
2517 | fs_initcall(rb_init_debugfs); |