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 | { | |
465634ad RR |
171 | unsigned length = rb_event_length(event); |
172 | if (event->type != RINGBUF_TYPE_DATA) | |
173 | return length; | |
174 | length -= RB_EVNT_HDR_SIZE; | |
175 | if (length > RB_MAX_SMALL_DATA + sizeof(event->array[0])) | |
176 | length -= sizeof(event->array[0]); | |
177 | return length; | |
7a8e76a3 | 178 | } |
c4f50183 | 179 | EXPORT_SYMBOL_GPL(ring_buffer_event_length); |
7a8e76a3 SR |
180 | |
181 | /* inline for ring buffer fast paths */ | |
182 | static inline void * | |
183 | rb_event_data(struct ring_buffer_event *event) | |
184 | { | |
185 | BUG_ON(event->type != RINGBUF_TYPE_DATA); | |
186 | /* If length is in len field, then array[0] has the data */ | |
187 | if (event->len) | |
188 | return (void *)&event->array[0]; | |
189 | /* Otherwise length is in array[0] and array[1] has the data */ | |
190 | return (void *)&event->array[1]; | |
191 | } | |
192 | ||
193 | /** | |
194 | * ring_buffer_event_data - return the data of the event | |
195 | * @event: the event to get the data from | |
196 | */ | |
197 | void *ring_buffer_event_data(struct ring_buffer_event *event) | |
198 | { | |
199 | return rb_event_data(event); | |
200 | } | |
c4f50183 | 201 | EXPORT_SYMBOL_GPL(ring_buffer_event_data); |
7a8e76a3 SR |
202 | |
203 | #define for_each_buffer_cpu(buffer, cpu) \ | |
9e01c1b7 | 204 | for_each_cpu(cpu, buffer->cpumask) |
7a8e76a3 SR |
205 | |
206 | #define TS_SHIFT 27 | |
207 | #define TS_MASK ((1ULL << TS_SHIFT) - 1) | |
208 | #define TS_DELTA_TEST (~TS_MASK) | |
209 | ||
abc9b56d | 210 | struct buffer_data_page { |
e4c2ce82 | 211 | u64 time_stamp; /* page time stamp */ |
bf41a158 | 212 | local_t commit; /* write commited index */ |
abc9b56d SR |
213 | unsigned char data[]; /* data of buffer page */ |
214 | }; | |
215 | ||
216 | struct buffer_page { | |
217 | local_t write; /* index for next write */ | |
6f807acd | 218 | unsigned read; /* index for next read */ |
e4c2ce82 | 219 | struct list_head list; /* list of free pages */ |
abc9b56d | 220 | struct buffer_data_page *page; /* Actual data page */ |
7a8e76a3 SR |
221 | }; |
222 | ||
044fa782 | 223 | static void rb_init_page(struct buffer_data_page *bpage) |
abc9b56d | 224 | { |
044fa782 | 225 | local_set(&bpage->commit, 0); |
abc9b56d SR |
226 | } |
227 | ||
ed56829c SR |
228 | /* |
229 | * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing | |
230 | * this issue out. | |
231 | */ | |
232 | static inline void free_buffer_page(struct buffer_page *bpage) | |
233 | { | |
e4c2ce82 | 234 | if (bpage->page) |
6ae2a076 | 235 | free_page((unsigned long)bpage->page); |
e4c2ce82 | 236 | kfree(bpage); |
ed56829c SR |
237 | } |
238 | ||
7a8e76a3 SR |
239 | /* |
240 | * We need to fit the time_stamp delta into 27 bits. | |
241 | */ | |
242 | static inline int test_time_stamp(u64 delta) | |
243 | { | |
244 | if (delta & TS_DELTA_TEST) | |
245 | return 1; | |
246 | return 0; | |
247 | } | |
248 | ||
082605de | 249 | #define BUF_PAGE_SIZE (PAGE_SIZE - offsetof(struct buffer_data_page, data)) |
7a8e76a3 SR |
250 | |
251 | /* | |
252 | * head_page == tail_page && head == tail then buffer is empty. | |
253 | */ | |
254 | struct ring_buffer_per_cpu { | |
255 | int cpu; | |
256 | struct ring_buffer *buffer; | |
f83c9d0f | 257 | spinlock_t reader_lock; /* serialize readers */ |
3e03fb7f | 258 | raw_spinlock_t lock; |
7a8e76a3 SR |
259 | struct lock_class_key lock_key; |
260 | struct list_head pages; | |
6f807acd SR |
261 | struct buffer_page *head_page; /* read from head */ |
262 | struct buffer_page *tail_page; /* write to tail */ | |
bf41a158 | 263 | struct buffer_page *commit_page; /* commited pages */ |
d769041f | 264 | struct buffer_page *reader_page; |
7a8e76a3 SR |
265 | unsigned long overrun; |
266 | unsigned long entries; | |
267 | u64 write_stamp; | |
268 | u64 read_stamp; | |
269 | atomic_t record_disabled; | |
270 | }; | |
271 | ||
272 | struct ring_buffer { | |
7a8e76a3 SR |
273 | unsigned pages; |
274 | unsigned flags; | |
275 | int cpus; | |
9e01c1b7 | 276 | cpumask_var_t cpumask; |
7a8e76a3 SR |
277 | atomic_t record_disabled; |
278 | ||
279 | struct mutex mutex; | |
280 | ||
281 | struct ring_buffer_per_cpu **buffers; | |
282 | }; | |
283 | ||
284 | struct ring_buffer_iter { | |
285 | struct ring_buffer_per_cpu *cpu_buffer; | |
286 | unsigned long head; | |
287 | struct buffer_page *head_page; | |
288 | u64 read_stamp; | |
289 | }; | |
290 | ||
f536aafc | 291 | /* buffer may be either ring_buffer or ring_buffer_per_cpu */ |
bf41a158 | 292 | #define RB_WARN_ON(buffer, cond) \ |
3e89c7bb SR |
293 | ({ \ |
294 | int _____ret = unlikely(cond); \ | |
295 | if (_____ret) { \ | |
bf41a158 SR |
296 | atomic_inc(&buffer->record_disabled); \ |
297 | WARN_ON(1); \ | |
298 | } \ | |
3e89c7bb SR |
299 | _____ret; \ |
300 | }) | |
f536aafc | 301 | |
7a8e76a3 SR |
302 | /** |
303 | * check_pages - integrity check of buffer pages | |
304 | * @cpu_buffer: CPU buffer with pages to test | |
305 | * | |
306 | * As a safty measure we check to make sure the data pages have not | |
307 | * been corrupted. | |
308 | */ | |
309 | static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) | |
310 | { | |
311 | struct list_head *head = &cpu_buffer->pages; | |
044fa782 | 312 | struct buffer_page *bpage, *tmp; |
7a8e76a3 | 313 | |
3e89c7bb SR |
314 | if (RB_WARN_ON(cpu_buffer, head->next->prev != head)) |
315 | return -1; | |
316 | if (RB_WARN_ON(cpu_buffer, head->prev->next != head)) | |
317 | return -1; | |
7a8e76a3 | 318 | |
044fa782 | 319 | list_for_each_entry_safe(bpage, tmp, head, list) { |
3e89c7bb | 320 | if (RB_WARN_ON(cpu_buffer, |
044fa782 | 321 | bpage->list.next->prev != &bpage->list)) |
3e89c7bb SR |
322 | return -1; |
323 | if (RB_WARN_ON(cpu_buffer, | |
044fa782 | 324 | bpage->list.prev->next != &bpage->list)) |
3e89c7bb | 325 | return -1; |
7a8e76a3 SR |
326 | } |
327 | ||
328 | return 0; | |
329 | } | |
330 | ||
7a8e76a3 SR |
331 | static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, |
332 | unsigned nr_pages) | |
333 | { | |
334 | struct list_head *head = &cpu_buffer->pages; | |
044fa782 | 335 | struct buffer_page *bpage, *tmp; |
7a8e76a3 SR |
336 | unsigned long addr; |
337 | LIST_HEAD(pages); | |
338 | unsigned i; | |
339 | ||
340 | for (i = 0; i < nr_pages; i++) { | |
044fa782 | 341 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
aa1e0e3b | 342 | GFP_KERNEL, cpu_to_node(cpu_buffer->cpu)); |
044fa782 | 343 | if (!bpage) |
e4c2ce82 | 344 | goto free_pages; |
044fa782 | 345 | list_add(&bpage->list, &pages); |
e4c2ce82 | 346 | |
7a8e76a3 SR |
347 | addr = __get_free_page(GFP_KERNEL); |
348 | if (!addr) | |
349 | goto free_pages; | |
044fa782 SR |
350 | bpage->page = (void *)addr; |
351 | rb_init_page(bpage->page); | |
7a8e76a3 SR |
352 | } |
353 | ||
354 | list_splice(&pages, head); | |
355 | ||
356 | rb_check_pages(cpu_buffer); | |
357 | ||
358 | return 0; | |
359 | ||
360 | free_pages: | |
044fa782 SR |
361 | list_for_each_entry_safe(bpage, tmp, &pages, list) { |
362 | list_del_init(&bpage->list); | |
363 | free_buffer_page(bpage); | |
7a8e76a3 SR |
364 | } |
365 | return -ENOMEM; | |
366 | } | |
367 | ||
368 | static struct ring_buffer_per_cpu * | |
369 | rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu) | |
370 | { | |
371 | struct ring_buffer_per_cpu *cpu_buffer; | |
044fa782 | 372 | struct buffer_page *bpage; |
d769041f | 373 | unsigned long addr; |
7a8e76a3 SR |
374 | int ret; |
375 | ||
376 | cpu_buffer = kzalloc_node(ALIGN(sizeof(*cpu_buffer), cache_line_size()), | |
377 | GFP_KERNEL, cpu_to_node(cpu)); | |
378 | if (!cpu_buffer) | |
379 | return NULL; | |
380 | ||
381 | cpu_buffer->cpu = cpu; | |
382 | cpu_buffer->buffer = buffer; | |
f83c9d0f | 383 | spin_lock_init(&cpu_buffer->reader_lock); |
3e03fb7f | 384 | cpu_buffer->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; |
7a8e76a3 SR |
385 | INIT_LIST_HEAD(&cpu_buffer->pages); |
386 | ||
044fa782 | 387 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
e4c2ce82 | 388 | GFP_KERNEL, cpu_to_node(cpu)); |
044fa782 | 389 | if (!bpage) |
e4c2ce82 SR |
390 | goto fail_free_buffer; |
391 | ||
044fa782 | 392 | cpu_buffer->reader_page = bpage; |
d769041f SR |
393 | addr = __get_free_page(GFP_KERNEL); |
394 | if (!addr) | |
e4c2ce82 | 395 | goto fail_free_reader; |
044fa782 SR |
396 | bpage->page = (void *)addr; |
397 | rb_init_page(bpage->page); | |
e4c2ce82 | 398 | |
d769041f | 399 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); |
d769041f | 400 | |
7a8e76a3 SR |
401 | ret = rb_allocate_pages(cpu_buffer, buffer->pages); |
402 | if (ret < 0) | |
d769041f | 403 | goto fail_free_reader; |
7a8e76a3 SR |
404 | |
405 | cpu_buffer->head_page | |
406 | = list_entry(cpu_buffer->pages.next, struct buffer_page, list); | |
bf41a158 | 407 | cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; |
7a8e76a3 SR |
408 | |
409 | return cpu_buffer; | |
410 | ||
d769041f SR |
411 | fail_free_reader: |
412 | free_buffer_page(cpu_buffer->reader_page); | |
413 | ||
7a8e76a3 SR |
414 | fail_free_buffer: |
415 | kfree(cpu_buffer); | |
416 | return NULL; | |
417 | } | |
418 | ||
419 | static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) | |
420 | { | |
421 | struct list_head *head = &cpu_buffer->pages; | |
044fa782 | 422 | struct buffer_page *bpage, *tmp; |
7a8e76a3 | 423 | |
d769041f SR |
424 | list_del_init(&cpu_buffer->reader_page->list); |
425 | free_buffer_page(cpu_buffer->reader_page); | |
426 | ||
044fa782 SR |
427 | list_for_each_entry_safe(bpage, tmp, head, list) { |
428 | list_del_init(&bpage->list); | |
429 | free_buffer_page(bpage); | |
7a8e76a3 SR |
430 | } |
431 | kfree(cpu_buffer); | |
432 | } | |
433 | ||
a7b13743 SR |
434 | /* |
435 | * Causes compile errors if the struct buffer_page gets bigger | |
436 | * than the struct page. | |
437 | */ | |
438 | extern int ring_buffer_page_too_big(void); | |
439 | ||
7a8e76a3 SR |
440 | /** |
441 | * ring_buffer_alloc - allocate a new ring_buffer | |
68814b58 | 442 | * @size: the size in bytes per cpu that is needed. |
7a8e76a3 SR |
443 | * @flags: attributes to set for the ring buffer. |
444 | * | |
445 | * Currently the only flag that is available is the RB_FL_OVERWRITE | |
446 | * flag. This flag means that the buffer will overwrite old data | |
447 | * when the buffer wraps. If this flag is not set, the buffer will | |
448 | * drop data when the tail hits the head. | |
449 | */ | |
450 | struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags) | |
451 | { | |
452 | struct ring_buffer *buffer; | |
453 | int bsize; | |
454 | int cpu; | |
455 | ||
a7b13743 SR |
456 | /* Paranoid! Optimizes out when all is well */ |
457 | if (sizeof(struct buffer_page) > sizeof(struct page)) | |
458 | ring_buffer_page_too_big(); | |
459 | ||
460 | ||
7a8e76a3 SR |
461 | /* keep it in its own cache line */ |
462 | buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()), | |
463 | GFP_KERNEL); | |
464 | if (!buffer) | |
465 | return NULL; | |
466 | ||
9e01c1b7 RR |
467 | if (!alloc_cpumask_var(&buffer->cpumask, GFP_KERNEL)) |
468 | goto fail_free_buffer; | |
469 | ||
7a8e76a3 SR |
470 | buffer->pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
471 | buffer->flags = flags; | |
472 | ||
473 | /* need at least two pages */ | |
474 | if (buffer->pages == 1) | |
475 | buffer->pages++; | |
476 | ||
9e01c1b7 | 477 | cpumask_copy(buffer->cpumask, cpu_possible_mask); |
7a8e76a3 SR |
478 | buffer->cpus = nr_cpu_ids; |
479 | ||
480 | bsize = sizeof(void *) * nr_cpu_ids; | |
481 | buffer->buffers = kzalloc(ALIGN(bsize, cache_line_size()), | |
482 | GFP_KERNEL); | |
483 | if (!buffer->buffers) | |
9e01c1b7 | 484 | goto fail_free_cpumask; |
7a8e76a3 SR |
485 | |
486 | for_each_buffer_cpu(buffer, cpu) { | |
487 | buffer->buffers[cpu] = | |
488 | rb_allocate_cpu_buffer(buffer, cpu); | |
489 | if (!buffer->buffers[cpu]) | |
490 | goto fail_free_buffers; | |
491 | } | |
492 | ||
493 | mutex_init(&buffer->mutex); | |
494 | ||
495 | return buffer; | |
496 | ||
497 | fail_free_buffers: | |
498 | for_each_buffer_cpu(buffer, cpu) { | |
499 | if (buffer->buffers[cpu]) | |
500 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
501 | } | |
502 | kfree(buffer->buffers); | |
503 | ||
9e01c1b7 RR |
504 | fail_free_cpumask: |
505 | free_cpumask_var(buffer->cpumask); | |
506 | ||
7a8e76a3 SR |
507 | fail_free_buffer: |
508 | kfree(buffer); | |
509 | return NULL; | |
510 | } | |
c4f50183 | 511 | EXPORT_SYMBOL_GPL(ring_buffer_alloc); |
7a8e76a3 SR |
512 | |
513 | /** | |
514 | * ring_buffer_free - free a ring buffer. | |
515 | * @buffer: the buffer to free. | |
516 | */ | |
517 | void | |
518 | ring_buffer_free(struct ring_buffer *buffer) | |
519 | { | |
520 | int cpu; | |
521 | ||
522 | for_each_buffer_cpu(buffer, cpu) | |
523 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
524 | ||
9e01c1b7 RR |
525 | free_cpumask_var(buffer->cpumask); |
526 | ||
7a8e76a3 SR |
527 | kfree(buffer); |
528 | } | |
c4f50183 | 529 | EXPORT_SYMBOL_GPL(ring_buffer_free); |
7a8e76a3 SR |
530 | |
531 | static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer); | |
532 | ||
533 | static void | |
534 | rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages) | |
535 | { | |
044fa782 | 536 | struct buffer_page *bpage; |
7a8e76a3 SR |
537 | struct list_head *p; |
538 | unsigned i; | |
539 | ||
540 | atomic_inc(&cpu_buffer->record_disabled); | |
541 | synchronize_sched(); | |
542 | ||
543 | for (i = 0; i < nr_pages; i++) { | |
3e89c7bb SR |
544 | if (RB_WARN_ON(cpu_buffer, list_empty(&cpu_buffer->pages))) |
545 | return; | |
7a8e76a3 | 546 | p = cpu_buffer->pages.next; |
044fa782 SR |
547 | bpage = list_entry(p, struct buffer_page, list); |
548 | list_del_init(&bpage->list); | |
549 | free_buffer_page(bpage); | |
7a8e76a3 | 550 | } |
3e89c7bb SR |
551 | if (RB_WARN_ON(cpu_buffer, list_empty(&cpu_buffer->pages))) |
552 | return; | |
7a8e76a3 SR |
553 | |
554 | rb_reset_cpu(cpu_buffer); | |
555 | ||
556 | rb_check_pages(cpu_buffer); | |
557 | ||
558 | atomic_dec(&cpu_buffer->record_disabled); | |
559 | ||
560 | } | |
561 | ||
562 | static void | |
563 | rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer, | |
564 | struct list_head *pages, unsigned nr_pages) | |
565 | { | |
044fa782 | 566 | struct buffer_page *bpage; |
7a8e76a3 SR |
567 | struct list_head *p; |
568 | unsigned i; | |
569 | ||
570 | atomic_inc(&cpu_buffer->record_disabled); | |
571 | synchronize_sched(); | |
572 | ||
573 | for (i = 0; i < nr_pages; i++) { | |
3e89c7bb SR |
574 | if (RB_WARN_ON(cpu_buffer, list_empty(pages))) |
575 | return; | |
7a8e76a3 | 576 | p = pages->next; |
044fa782 SR |
577 | bpage = list_entry(p, struct buffer_page, list); |
578 | list_del_init(&bpage->list); | |
579 | list_add_tail(&bpage->list, &cpu_buffer->pages); | |
7a8e76a3 SR |
580 | } |
581 | rb_reset_cpu(cpu_buffer); | |
582 | ||
583 | rb_check_pages(cpu_buffer); | |
584 | ||
585 | atomic_dec(&cpu_buffer->record_disabled); | |
586 | } | |
587 | ||
588 | /** | |
589 | * ring_buffer_resize - resize the ring buffer | |
590 | * @buffer: the buffer to resize. | |
591 | * @size: the new size. | |
592 | * | |
593 | * The tracer is responsible for making sure that the buffer is | |
594 | * not being used while changing the size. | |
595 | * Note: We may be able to change the above requirement by using | |
596 | * RCU synchronizations. | |
597 | * | |
598 | * Minimum size is 2 * BUF_PAGE_SIZE. | |
599 | * | |
600 | * Returns -1 on failure. | |
601 | */ | |
602 | int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size) | |
603 | { | |
604 | struct ring_buffer_per_cpu *cpu_buffer; | |
605 | unsigned nr_pages, rm_pages, new_pages; | |
044fa782 | 606 | struct buffer_page *bpage, *tmp; |
7a8e76a3 SR |
607 | unsigned long buffer_size; |
608 | unsigned long addr; | |
609 | LIST_HEAD(pages); | |
610 | int i, cpu; | |
611 | ||
ee51a1de IM |
612 | /* |
613 | * Always succeed at resizing a non-existent buffer: | |
614 | */ | |
615 | if (!buffer) | |
616 | return size; | |
617 | ||
7a8e76a3 SR |
618 | size = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
619 | size *= BUF_PAGE_SIZE; | |
620 | buffer_size = buffer->pages * BUF_PAGE_SIZE; | |
621 | ||
622 | /* we need a minimum of two pages */ | |
623 | if (size < BUF_PAGE_SIZE * 2) | |
624 | size = BUF_PAGE_SIZE * 2; | |
625 | ||
626 | if (size == buffer_size) | |
627 | return size; | |
628 | ||
629 | mutex_lock(&buffer->mutex); | |
630 | ||
631 | nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); | |
632 | ||
633 | if (size < buffer_size) { | |
634 | ||
635 | /* easy case, just free pages */ | |
3e89c7bb SR |
636 | if (RB_WARN_ON(buffer, nr_pages >= buffer->pages)) { |
637 | mutex_unlock(&buffer->mutex); | |
638 | return -1; | |
639 | } | |
7a8e76a3 SR |
640 | |
641 | rm_pages = buffer->pages - nr_pages; | |
642 | ||
643 | for_each_buffer_cpu(buffer, cpu) { | |
644 | cpu_buffer = buffer->buffers[cpu]; | |
645 | rb_remove_pages(cpu_buffer, rm_pages); | |
646 | } | |
647 | goto out; | |
648 | } | |
649 | ||
650 | /* | |
651 | * This is a bit more difficult. We only want to add pages | |
652 | * when we can allocate enough for all CPUs. We do this | |
653 | * by allocating all the pages and storing them on a local | |
654 | * link list. If we succeed in our allocation, then we | |
655 | * add these pages to the cpu_buffers. Otherwise we just free | |
656 | * them all and return -ENOMEM; | |
657 | */ | |
3e89c7bb SR |
658 | if (RB_WARN_ON(buffer, nr_pages <= buffer->pages)) { |
659 | mutex_unlock(&buffer->mutex); | |
660 | return -1; | |
661 | } | |
f536aafc | 662 | |
7a8e76a3 SR |
663 | new_pages = nr_pages - buffer->pages; |
664 | ||
665 | for_each_buffer_cpu(buffer, cpu) { | |
666 | for (i = 0; i < new_pages; i++) { | |
044fa782 | 667 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), |
e4c2ce82 SR |
668 | cache_line_size()), |
669 | GFP_KERNEL, cpu_to_node(cpu)); | |
044fa782 | 670 | if (!bpage) |
e4c2ce82 | 671 | goto free_pages; |
044fa782 | 672 | list_add(&bpage->list, &pages); |
7a8e76a3 SR |
673 | addr = __get_free_page(GFP_KERNEL); |
674 | if (!addr) | |
675 | goto free_pages; | |
044fa782 SR |
676 | bpage->page = (void *)addr; |
677 | rb_init_page(bpage->page); | |
7a8e76a3 SR |
678 | } |
679 | } | |
680 | ||
681 | for_each_buffer_cpu(buffer, cpu) { | |
682 | cpu_buffer = buffer->buffers[cpu]; | |
683 | rb_insert_pages(cpu_buffer, &pages, new_pages); | |
684 | } | |
685 | ||
3e89c7bb SR |
686 | if (RB_WARN_ON(buffer, !list_empty(&pages))) { |
687 | mutex_unlock(&buffer->mutex); | |
688 | return -1; | |
689 | } | |
7a8e76a3 SR |
690 | |
691 | out: | |
692 | buffer->pages = nr_pages; | |
693 | mutex_unlock(&buffer->mutex); | |
694 | ||
695 | return size; | |
696 | ||
697 | free_pages: | |
044fa782 SR |
698 | list_for_each_entry_safe(bpage, tmp, &pages, list) { |
699 | list_del_init(&bpage->list); | |
700 | free_buffer_page(bpage); | |
7a8e76a3 | 701 | } |
641d2f63 | 702 | mutex_unlock(&buffer->mutex); |
7a8e76a3 SR |
703 | return -ENOMEM; |
704 | } | |
c4f50183 | 705 | EXPORT_SYMBOL_GPL(ring_buffer_resize); |
7a8e76a3 | 706 | |
7a8e76a3 SR |
707 | static inline int rb_null_event(struct ring_buffer_event *event) |
708 | { | |
709 | return event->type == RINGBUF_TYPE_PADDING; | |
710 | } | |
711 | ||
8789a9e7 | 712 | static inline void * |
044fa782 | 713 | __rb_data_page_index(struct buffer_data_page *bpage, unsigned index) |
8789a9e7 | 714 | { |
044fa782 | 715 | return bpage->data + index; |
8789a9e7 SR |
716 | } |
717 | ||
044fa782 | 718 | static inline void *__rb_page_index(struct buffer_page *bpage, unsigned index) |
7a8e76a3 | 719 | { |
044fa782 | 720 | return bpage->page->data + index; |
7a8e76a3 SR |
721 | } |
722 | ||
723 | static inline struct ring_buffer_event * | |
d769041f | 724 | rb_reader_event(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 725 | { |
6f807acd SR |
726 | return __rb_page_index(cpu_buffer->reader_page, |
727 | cpu_buffer->reader_page->read); | |
728 | } | |
729 | ||
730 | static inline struct ring_buffer_event * | |
731 | rb_head_event(struct ring_buffer_per_cpu *cpu_buffer) | |
732 | { | |
733 | return __rb_page_index(cpu_buffer->head_page, | |
734 | cpu_buffer->head_page->read); | |
7a8e76a3 SR |
735 | } |
736 | ||
737 | static inline struct ring_buffer_event * | |
738 | rb_iter_head_event(struct ring_buffer_iter *iter) | |
739 | { | |
6f807acd | 740 | return __rb_page_index(iter->head_page, iter->head); |
7a8e76a3 SR |
741 | } |
742 | ||
bf41a158 SR |
743 | static inline unsigned rb_page_write(struct buffer_page *bpage) |
744 | { | |
745 | return local_read(&bpage->write); | |
746 | } | |
747 | ||
748 | static inline unsigned rb_page_commit(struct buffer_page *bpage) | |
749 | { | |
abc9b56d | 750 | return local_read(&bpage->page->commit); |
bf41a158 SR |
751 | } |
752 | ||
753 | /* Size is determined by what has been commited */ | |
754 | static inline unsigned rb_page_size(struct buffer_page *bpage) | |
755 | { | |
756 | return rb_page_commit(bpage); | |
757 | } | |
758 | ||
759 | static inline unsigned | |
760 | rb_commit_index(struct ring_buffer_per_cpu *cpu_buffer) | |
761 | { | |
762 | return rb_page_commit(cpu_buffer->commit_page); | |
763 | } | |
764 | ||
765 | static inline unsigned rb_head_size(struct ring_buffer_per_cpu *cpu_buffer) | |
766 | { | |
767 | return rb_page_commit(cpu_buffer->head_page); | |
768 | } | |
769 | ||
7a8e76a3 SR |
770 | /* |
771 | * When the tail hits the head and the buffer is in overwrite mode, | |
772 | * the head jumps to the next page and all content on the previous | |
773 | * page is discarded. But before doing so, we update the overrun | |
774 | * variable of the buffer. | |
775 | */ | |
776 | static void rb_update_overflow(struct ring_buffer_per_cpu *cpu_buffer) | |
777 | { | |
778 | struct ring_buffer_event *event; | |
779 | unsigned long head; | |
780 | ||
781 | for (head = 0; head < rb_head_size(cpu_buffer); | |
782 | head += rb_event_length(event)) { | |
783 | ||
6f807acd | 784 | event = __rb_page_index(cpu_buffer->head_page, head); |
3e89c7bb SR |
785 | if (RB_WARN_ON(cpu_buffer, rb_null_event(event))) |
786 | return; | |
7a8e76a3 SR |
787 | /* Only count data entries */ |
788 | if (event->type != RINGBUF_TYPE_DATA) | |
789 | continue; | |
790 | cpu_buffer->overrun++; | |
791 | cpu_buffer->entries--; | |
792 | } | |
793 | } | |
794 | ||
795 | static inline void rb_inc_page(struct ring_buffer_per_cpu *cpu_buffer, | |
044fa782 | 796 | struct buffer_page **bpage) |
7a8e76a3 | 797 | { |
044fa782 | 798 | struct list_head *p = (*bpage)->list.next; |
7a8e76a3 SR |
799 | |
800 | if (p == &cpu_buffer->pages) | |
801 | p = p->next; | |
802 | ||
044fa782 | 803 | *bpage = list_entry(p, struct buffer_page, list); |
7a8e76a3 SR |
804 | } |
805 | ||
bf41a158 SR |
806 | static inline unsigned |
807 | rb_event_index(struct ring_buffer_event *event) | |
808 | { | |
809 | unsigned long addr = (unsigned long)event; | |
810 | ||
811 | return (addr & ~PAGE_MASK) - (PAGE_SIZE - BUF_PAGE_SIZE); | |
812 | } | |
813 | ||
814 | static inline int | |
815 | rb_is_commit(struct ring_buffer_per_cpu *cpu_buffer, | |
816 | struct ring_buffer_event *event) | |
817 | { | |
818 | unsigned long addr = (unsigned long)event; | |
819 | unsigned long index; | |
820 | ||
821 | index = rb_event_index(event); | |
822 | addr &= PAGE_MASK; | |
823 | ||
824 | return cpu_buffer->commit_page->page == (void *)addr && | |
825 | rb_commit_index(cpu_buffer) == index; | |
826 | } | |
827 | ||
7a8e76a3 | 828 | static inline void |
bf41a158 SR |
829 | rb_set_commit_event(struct ring_buffer_per_cpu *cpu_buffer, |
830 | struct ring_buffer_event *event) | |
7a8e76a3 | 831 | { |
bf41a158 SR |
832 | unsigned long addr = (unsigned long)event; |
833 | unsigned long index; | |
834 | ||
835 | index = rb_event_index(event); | |
836 | addr &= PAGE_MASK; | |
837 | ||
838 | while (cpu_buffer->commit_page->page != (void *)addr) { | |
3e89c7bb SR |
839 | if (RB_WARN_ON(cpu_buffer, |
840 | cpu_buffer->commit_page == cpu_buffer->tail_page)) | |
841 | return; | |
abc9b56d | 842 | cpu_buffer->commit_page->page->commit = |
bf41a158 SR |
843 | cpu_buffer->commit_page->write; |
844 | rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); | |
abc9b56d SR |
845 | cpu_buffer->write_stamp = |
846 | cpu_buffer->commit_page->page->time_stamp; | |
bf41a158 SR |
847 | } |
848 | ||
849 | /* Now set the commit to the event's index */ | |
abc9b56d | 850 | local_set(&cpu_buffer->commit_page->page->commit, index); |
7a8e76a3 SR |
851 | } |
852 | ||
bf41a158 SR |
853 | static inline void |
854 | rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) | |
7a8e76a3 | 855 | { |
bf41a158 SR |
856 | /* |
857 | * We only race with interrupts and NMIs on this CPU. | |
858 | * If we own the commit event, then we can commit | |
859 | * all others that interrupted us, since the interruptions | |
860 | * are in stack format (they finish before they come | |
861 | * back to us). This allows us to do a simple loop to | |
862 | * assign the commit to the tail. | |
863 | */ | |
a8ccf1d6 | 864 | again: |
bf41a158 | 865 | while (cpu_buffer->commit_page != cpu_buffer->tail_page) { |
abc9b56d | 866 | cpu_buffer->commit_page->page->commit = |
bf41a158 SR |
867 | cpu_buffer->commit_page->write; |
868 | rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); | |
abc9b56d SR |
869 | cpu_buffer->write_stamp = |
870 | cpu_buffer->commit_page->page->time_stamp; | |
bf41a158 SR |
871 | /* add barrier to keep gcc from optimizing too much */ |
872 | barrier(); | |
873 | } | |
874 | while (rb_commit_index(cpu_buffer) != | |
875 | rb_page_write(cpu_buffer->commit_page)) { | |
abc9b56d | 876 | cpu_buffer->commit_page->page->commit = |
bf41a158 SR |
877 | cpu_buffer->commit_page->write; |
878 | barrier(); | |
879 | } | |
a8ccf1d6 SR |
880 | |
881 | /* again, keep gcc from optimizing */ | |
882 | barrier(); | |
883 | ||
884 | /* | |
885 | * If an interrupt came in just after the first while loop | |
886 | * and pushed the tail page forward, we will be left with | |
887 | * a dangling commit that will never go forward. | |
888 | */ | |
889 | if (unlikely(cpu_buffer->commit_page != cpu_buffer->tail_page)) | |
890 | goto again; | |
7a8e76a3 SR |
891 | } |
892 | ||
d769041f | 893 | static void rb_reset_reader_page(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 894 | { |
abc9b56d | 895 | cpu_buffer->read_stamp = cpu_buffer->reader_page->page->time_stamp; |
6f807acd | 896 | cpu_buffer->reader_page->read = 0; |
d769041f SR |
897 | } |
898 | ||
899 | static inline void rb_inc_iter(struct ring_buffer_iter *iter) | |
900 | { | |
901 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
902 | ||
903 | /* | |
904 | * The iterator could be on the reader page (it starts there). | |
905 | * But the head could have moved, since the reader was | |
906 | * found. Check for this case and assign the iterator | |
907 | * to the head page instead of next. | |
908 | */ | |
909 | if (iter->head_page == cpu_buffer->reader_page) | |
910 | iter->head_page = cpu_buffer->head_page; | |
911 | else | |
912 | rb_inc_page(cpu_buffer, &iter->head_page); | |
913 | ||
abc9b56d | 914 | iter->read_stamp = iter->head_page->page->time_stamp; |
7a8e76a3 SR |
915 | iter->head = 0; |
916 | } | |
917 | ||
918 | /** | |
919 | * ring_buffer_update_event - update event type and data | |
920 | * @event: the even to update | |
921 | * @type: the type of event | |
922 | * @length: the size of the event field in the ring buffer | |
923 | * | |
924 | * Update the type and data fields of the event. The length | |
925 | * is the actual size that is written to the ring buffer, | |
926 | * and with this, we can determine what to place into the | |
927 | * data field. | |
928 | */ | |
929 | static inline void | |
930 | rb_update_event(struct ring_buffer_event *event, | |
931 | unsigned type, unsigned length) | |
932 | { | |
933 | event->type = type; | |
934 | ||
935 | switch (type) { | |
936 | ||
937 | case RINGBUF_TYPE_PADDING: | |
938 | break; | |
939 | ||
940 | case RINGBUF_TYPE_TIME_EXTEND: | |
941 | event->len = | |
942 | (RB_LEN_TIME_EXTEND + (RB_ALIGNMENT-1)) | |
943 | >> RB_ALIGNMENT_SHIFT; | |
944 | break; | |
945 | ||
946 | case RINGBUF_TYPE_TIME_STAMP: | |
947 | event->len = | |
948 | (RB_LEN_TIME_STAMP + (RB_ALIGNMENT-1)) | |
949 | >> RB_ALIGNMENT_SHIFT; | |
950 | break; | |
951 | ||
952 | case RINGBUF_TYPE_DATA: | |
953 | length -= RB_EVNT_HDR_SIZE; | |
954 | if (length > RB_MAX_SMALL_DATA) { | |
955 | event->len = 0; | |
956 | event->array[0] = length; | |
957 | } else | |
958 | event->len = | |
959 | (length + (RB_ALIGNMENT-1)) | |
960 | >> RB_ALIGNMENT_SHIFT; | |
961 | break; | |
962 | default: | |
963 | BUG(); | |
964 | } | |
965 | } | |
966 | ||
967 | static inline unsigned rb_calculate_event_length(unsigned length) | |
968 | { | |
969 | struct ring_buffer_event event; /* Used only for sizeof array */ | |
970 | ||
971 | /* zero length can cause confusions */ | |
972 | if (!length) | |
973 | length = 1; | |
974 | ||
975 | if (length > RB_MAX_SMALL_DATA) | |
976 | length += sizeof(event.array[0]); | |
977 | ||
978 | length += RB_EVNT_HDR_SIZE; | |
979 | length = ALIGN(length, RB_ALIGNMENT); | |
980 | ||
981 | return length; | |
982 | } | |
983 | ||
984 | static struct ring_buffer_event * | |
985 | __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, | |
986 | unsigned type, unsigned long length, u64 *ts) | |
987 | { | |
98db8df7 | 988 | struct buffer_page *tail_page, *head_page, *reader_page, *commit_page; |
bf41a158 | 989 | unsigned long tail, write; |
7a8e76a3 SR |
990 | struct ring_buffer *buffer = cpu_buffer->buffer; |
991 | struct ring_buffer_event *event; | |
bf41a158 | 992 | unsigned long flags; |
7a8e76a3 | 993 | |
98db8df7 SR |
994 | commit_page = cpu_buffer->commit_page; |
995 | /* we just need to protect against interrupts */ | |
996 | barrier(); | |
7a8e76a3 | 997 | tail_page = cpu_buffer->tail_page; |
bf41a158 SR |
998 | write = local_add_return(length, &tail_page->write); |
999 | tail = write - length; | |
7a8e76a3 | 1000 | |
bf41a158 SR |
1001 | /* See if we shot pass the end of this buffer page */ |
1002 | if (write > BUF_PAGE_SIZE) { | |
7a8e76a3 SR |
1003 | struct buffer_page *next_page = tail_page; |
1004 | ||
3e03fb7f SR |
1005 | local_irq_save(flags); |
1006 | __raw_spin_lock(&cpu_buffer->lock); | |
bf41a158 | 1007 | |
7a8e76a3 SR |
1008 | rb_inc_page(cpu_buffer, &next_page); |
1009 | ||
d769041f SR |
1010 | head_page = cpu_buffer->head_page; |
1011 | reader_page = cpu_buffer->reader_page; | |
1012 | ||
1013 | /* we grabbed the lock before incrementing */ | |
3e89c7bb SR |
1014 | if (RB_WARN_ON(cpu_buffer, next_page == reader_page)) |
1015 | goto out_unlock; | |
bf41a158 SR |
1016 | |
1017 | /* | |
1018 | * If for some reason, we had an interrupt storm that made | |
1019 | * it all the way around the buffer, bail, and warn | |
1020 | * about it. | |
1021 | */ | |
98db8df7 | 1022 | if (unlikely(next_page == commit_page)) { |
bf41a158 SR |
1023 | WARN_ON_ONCE(1); |
1024 | goto out_unlock; | |
1025 | } | |
d769041f | 1026 | |
7a8e76a3 | 1027 | if (next_page == head_page) { |
551b4048 | 1028 | if (!(buffer->flags & RB_FL_OVERWRITE)) |
bf41a158 | 1029 | goto out_unlock; |
7a8e76a3 | 1030 | |
bf41a158 SR |
1031 | /* tail_page has not moved yet? */ |
1032 | if (tail_page == cpu_buffer->tail_page) { | |
1033 | /* count overflows */ | |
1034 | rb_update_overflow(cpu_buffer); | |
1035 | ||
1036 | rb_inc_page(cpu_buffer, &head_page); | |
1037 | cpu_buffer->head_page = head_page; | |
1038 | cpu_buffer->head_page->read = 0; | |
1039 | } | |
1040 | } | |
7a8e76a3 | 1041 | |
bf41a158 SR |
1042 | /* |
1043 | * If the tail page is still the same as what we think | |
1044 | * it is, then it is up to us to update the tail | |
1045 | * pointer. | |
1046 | */ | |
1047 | if (tail_page == cpu_buffer->tail_page) { | |
1048 | local_set(&next_page->write, 0); | |
abc9b56d | 1049 | local_set(&next_page->page->commit, 0); |
bf41a158 SR |
1050 | cpu_buffer->tail_page = next_page; |
1051 | ||
1052 | /* reread the time stamp */ | |
1053 | *ts = ring_buffer_time_stamp(cpu_buffer->cpu); | |
abc9b56d | 1054 | cpu_buffer->tail_page->page->time_stamp = *ts; |
7a8e76a3 SR |
1055 | } |
1056 | ||
bf41a158 SR |
1057 | /* |
1058 | * The actual tail page has moved forward. | |
1059 | */ | |
1060 | if (tail < BUF_PAGE_SIZE) { | |
1061 | /* Mark the rest of the page with padding */ | |
6f807acd | 1062 | event = __rb_page_index(tail_page, tail); |
7a8e76a3 SR |
1063 | event->type = RINGBUF_TYPE_PADDING; |
1064 | } | |
1065 | ||
bf41a158 SR |
1066 | if (tail <= BUF_PAGE_SIZE) |
1067 | /* Set the write back to the previous setting */ | |
1068 | local_set(&tail_page->write, tail); | |
1069 | ||
1070 | /* | |
1071 | * If this was a commit entry that failed, | |
1072 | * increment that too | |
1073 | */ | |
1074 | if (tail_page == cpu_buffer->commit_page && | |
1075 | tail == rb_commit_index(cpu_buffer)) { | |
1076 | rb_set_commit_to_write(cpu_buffer); | |
1077 | } | |
1078 | ||
3e03fb7f SR |
1079 | __raw_spin_unlock(&cpu_buffer->lock); |
1080 | local_irq_restore(flags); | |
bf41a158 SR |
1081 | |
1082 | /* fail and let the caller try again */ | |
1083 | return ERR_PTR(-EAGAIN); | |
7a8e76a3 SR |
1084 | } |
1085 | ||
bf41a158 SR |
1086 | /* We reserved something on the buffer */ |
1087 | ||
3e89c7bb SR |
1088 | if (RB_WARN_ON(cpu_buffer, write > BUF_PAGE_SIZE)) |
1089 | return NULL; | |
7a8e76a3 | 1090 | |
6f807acd | 1091 | event = __rb_page_index(tail_page, tail); |
7a8e76a3 SR |
1092 | rb_update_event(event, type, length); |
1093 | ||
bf41a158 SR |
1094 | /* |
1095 | * If this is a commit and the tail is zero, then update | |
1096 | * this page's time stamp. | |
1097 | */ | |
1098 | if (!tail && rb_is_commit(cpu_buffer, event)) | |
abc9b56d | 1099 | cpu_buffer->commit_page->page->time_stamp = *ts; |
bf41a158 | 1100 | |
7a8e76a3 | 1101 | return event; |
bf41a158 SR |
1102 | |
1103 | out_unlock: | |
551b4048 LJ |
1104 | /* reset write */ |
1105 | if (tail <= BUF_PAGE_SIZE) | |
1106 | local_set(&tail_page->write, tail); | |
1107 | ||
3e03fb7f SR |
1108 | __raw_spin_unlock(&cpu_buffer->lock); |
1109 | local_irq_restore(flags); | |
bf41a158 | 1110 | return NULL; |
7a8e76a3 SR |
1111 | } |
1112 | ||
1113 | static int | |
1114 | rb_add_time_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
1115 | u64 *ts, u64 *delta) | |
1116 | { | |
1117 | struct ring_buffer_event *event; | |
1118 | static int once; | |
bf41a158 | 1119 | int ret; |
7a8e76a3 SR |
1120 | |
1121 | if (unlikely(*delta > (1ULL << 59) && !once++)) { | |
1122 | printk(KERN_WARNING "Delta way too big! %llu" | |
1123 | " ts=%llu write stamp = %llu\n", | |
e2862c94 SR |
1124 | (unsigned long long)*delta, |
1125 | (unsigned long long)*ts, | |
1126 | (unsigned long long)cpu_buffer->write_stamp); | |
7a8e76a3 SR |
1127 | WARN_ON(1); |
1128 | } | |
1129 | ||
1130 | /* | |
1131 | * The delta is too big, we to add a | |
1132 | * new timestamp. | |
1133 | */ | |
1134 | event = __rb_reserve_next(cpu_buffer, | |
1135 | RINGBUF_TYPE_TIME_EXTEND, | |
1136 | RB_LEN_TIME_EXTEND, | |
1137 | ts); | |
1138 | if (!event) | |
bf41a158 | 1139 | return -EBUSY; |
7a8e76a3 | 1140 | |
bf41a158 SR |
1141 | if (PTR_ERR(event) == -EAGAIN) |
1142 | return -EAGAIN; | |
1143 | ||
1144 | /* Only a commited time event can update the write stamp */ | |
1145 | if (rb_is_commit(cpu_buffer, event)) { | |
1146 | /* | |
1147 | * If this is the first on the page, then we need to | |
1148 | * update the page itself, and just put in a zero. | |
1149 | */ | |
1150 | if (rb_event_index(event)) { | |
1151 | event->time_delta = *delta & TS_MASK; | |
1152 | event->array[0] = *delta >> TS_SHIFT; | |
1153 | } else { | |
abc9b56d | 1154 | cpu_buffer->commit_page->page->time_stamp = *ts; |
bf41a158 SR |
1155 | event->time_delta = 0; |
1156 | event->array[0] = 0; | |
1157 | } | |
7a8e76a3 | 1158 | cpu_buffer->write_stamp = *ts; |
bf41a158 SR |
1159 | /* let the caller know this was the commit */ |
1160 | ret = 1; | |
1161 | } else { | |
1162 | /* Darn, this is just wasted space */ | |
1163 | event->time_delta = 0; | |
1164 | event->array[0] = 0; | |
1165 | ret = 0; | |
7a8e76a3 SR |
1166 | } |
1167 | ||
bf41a158 SR |
1168 | *delta = 0; |
1169 | ||
1170 | return ret; | |
7a8e76a3 SR |
1171 | } |
1172 | ||
1173 | static struct ring_buffer_event * | |
1174 | rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer, | |
1175 | unsigned type, unsigned long length) | |
1176 | { | |
1177 | struct ring_buffer_event *event; | |
1178 | u64 ts, delta; | |
bf41a158 | 1179 | int commit = 0; |
818e3dd3 | 1180 | int nr_loops = 0; |
7a8e76a3 | 1181 | |
bf41a158 | 1182 | again: |
818e3dd3 SR |
1183 | /* |
1184 | * We allow for interrupts to reenter here and do a trace. | |
1185 | * If one does, it will cause this original code to loop | |
1186 | * back here. Even with heavy interrupts happening, this | |
1187 | * should only happen a few times in a row. If this happens | |
1188 | * 1000 times in a row, there must be either an interrupt | |
1189 | * storm or we have something buggy. | |
1190 | * Bail! | |
1191 | */ | |
3e89c7bb | 1192 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000)) |
818e3dd3 | 1193 | return NULL; |
818e3dd3 | 1194 | |
7a8e76a3 SR |
1195 | ts = ring_buffer_time_stamp(cpu_buffer->cpu); |
1196 | ||
bf41a158 SR |
1197 | /* |
1198 | * Only the first commit can update the timestamp. | |
1199 | * Yes there is a race here. If an interrupt comes in | |
1200 | * just after the conditional and it traces too, then it | |
1201 | * will also check the deltas. More than one timestamp may | |
1202 | * also be made. But only the entry that did the actual | |
1203 | * commit will be something other than zero. | |
1204 | */ | |
1205 | if (cpu_buffer->tail_page == cpu_buffer->commit_page && | |
1206 | rb_page_write(cpu_buffer->tail_page) == | |
1207 | rb_commit_index(cpu_buffer)) { | |
1208 | ||
7a8e76a3 SR |
1209 | delta = ts - cpu_buffer->write_stamp; |
1210 | ||
bf41a158 SR |
1211 | /* make sure this delta is calculated here */ |
1212 | barrier(); | |
1213 | ||
1214 | /* Did the write stamp get updated already? */ | |
1215 | if (unlikely(ts < cpu_buffer->write_stamp)) | |
4143c5cb | 1216 | delta = 0; |
bf41a158 | 1217 | |
7a8e76a3 | 1218 | if (test_time_stamp(delta)) { |
7a8e76a3 | 1219 | |
bf41a158 SR |
1220 | commit = rb_add_time_stamp(cpu_buffer, &ts, &delta); |
1221 | ||
1222 | if (commit == -EBUSY) | |
7a8e76a3 | 1223 | return NULL; |
bf41a158 SR |
1224 | |
1225 | if (commit == -EAGAIN) | |
1226 | goto again; | |
1227 | ||
1228 | RB_WARN_ON(cpu_buffer, commit < 0); | |
7a8e76a3 | 1229 | } |
bf41a158 SR |
1230 | } else |
1231 | /* Non commits have zero deltas */ | |
7a8e76a3 | 1232 | delta = 0; |
7a8e76a3 SR |
1233 | |
1234 | event = __rb_reserve_next(cpu_buffer, type, length, &ts); | |
bf41a158 SR |
1235 | if (PTR_ERR(event) == -EAGAIN) |
1236 | goto again; | |
1237 | ||
1238 | if (!event) { | |
1239 | if (unlikely(commit)) | |
1240 | /* | |
1241 | * Ouch! We needed a timestamp and it was commited. But | |
1242 | * we didn't get our event reserved. | |
1243 | */ | |
1244 | rb_set_commit_to_write(cpu_buffer); | |
7a8e76a3 | 1245 | return NULL; |
bf41a158 | 1246 | } |
7a8e76a3 | 1247 | |
bf41a158 SR |
1248 | /* |
1249 | * If the timestamp was commited, make the commit our entry | |
1250 | * now so that we will update it when needed. | |
1251 | */ | |
1252 | if (commit) | |
1253 | rb_set_commit_event(cpu_buffer, event); | |
1254 | else if (!rb_is_commit(cpu_buffer, event)) | |
7a8e76a3 SR |
1255 | delta = 0; |
1256 | ||
1257 | event->time_delta = delta; | |
1258 | ||
1259 | return event; | |
1260 | } | |
1261 | ||
bf41a158 SR |
1262 | static DEFINE_PER_CPU(int, rb_need_resched); |
1263 | ||
7a8e76a3 SR |
1264 | /** |
1265 | * ring_buffer_lock_reserve - reserve a part of the buffer | |
1266 | * @buffer: the ring buffer to reserve from | |
1267 | * @length: the length of the data to reserve (excluding event header) | |
1268 | * @flags: a pointer to save the interrupt flags | |
1269 | * | |
1270 | * Returns a reseverd event on the ring buffer to copy directly to. | |
1271 | * The user of this interface will need to get the body to write into | |
1272 | * and can use the ring_buffer_event_data() interface. | |
1273 | * | |
1274 | * The length is the length of the data needed, not the event length | |
1275 | * which also includes the event header. | |
1276 | * | |
1277 | * Must be paired with ring_buffer_unlock_commit, unless NULL is returned. | |
1278 | * If NULL is returned, then nothing has been allocated or locked. | |
1279 | */ | |
1280 | struct ring_buffer_event * | |
1281 | ring_buffer_lock_reserve(struct ring_buffer *buffer, | |
1282 | unsigned long length, | |
1283 | unsigned long *flags) | |
1284 | { | |
1285 | struct ring_buffer_per_cpu *cpu_buffer; | |
1286 | struct ring_buffer_event *event; | |
bf41a158 | 1287 | int cpu, resched; |
7a8e76a3 | 1288 | |
033601a3 | 1289 | if (ring_buffer_flags != RB_BUFFERS_ON) |
a3583244 SR |
1290 | return NULL; |
1291 | ||
7a8e76a3 SR |
1292 | if (atomic_read(&buffer->record_disabled)) |
1293 | return NULL; | |
1294 | ||
bf41a158 | 1295 | /* If we are tracing schedule, we don't want to recurse */ |
182e9f5f | 1296 | resched = ftrace_preempt_disable(); |
bf41a158 | 1297 | |
7a8e76a3 SR |
1298 | cpu = raw_smp_processor_id(); |
1299 | ||
9e01c1b7 | 1300 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
d769041f | 1301 | goto out; |
7a8e76a3 SR |
1302 | |
1303 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 SR |
1304 | |
1305 | if (atomic_read(&cpu_buffer->record_disabled)) | |
d769041f | 1306 | goto out; |
7a8e76a3 SR |
1307 | |
1308 | length = rb_calculate_event_length(length); | |
1309 | if (length > BUF_PAGE_SIZE) | |
bf41a158 | 1310 | goto out; |
7a8e76a3 SR |
1311 | |
1312 | event = rb_reserve_next_event(cpu_buffer, RINGBUF_TYPE_DATA, length); | |
1313 | if (!event) | |
d769041f | 1314 | goto out; |
7a8e76a3 | 1315 | |
bf41a158 SR |
1316 | /* |
1317 | * Need to store resched state on this cpu. | |
1318 | * Only the first needs to. | |
1319 | */ | |
1320 | ||
1321 | if (preempt_count() == 1) | |
1322 | per_cpu(rb_need_resched, cpu) = resched; | |
1323 | ||
7a8e76a3 SR |
1324 | return event; |
1325 | ||
d769041f | 1326 | out: |
182e9f5f | 1327 | ftrace_preempt_enable(resched); |
7a8e76a3 SR |
1328 | return NULL; |
1329 | } | |
c4f50183 | 1330 | EXPORT_SYMBOL_GPL(ring_buffer_lock_reserve); |
7a8e76a3 SR |
1331 | |
1332 | static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, | |
1333 | struct ring_buffer_event *event) | |
1334 | { | |
7a8e76a3 | 1335 | cpu_buffer->entries++; |
bf41a158 SR |
1336 | |
1337 | /* Only process further if we own the commit */ | |
1338 | if (!rb_is_commit(cpu_buffer, event)) | |
1339 | return; | |
1340 | ||
1341 | cpu_buffer->write_stamp += event->time_delta; | |
1342 | ||
1343 | rb_set_commit_to_write(cpu_buffer); | |
7a8e76a3 SR |
1344 | } |
1345 | ||
1346 | /** | |
1347 | * ring_buffer_unlock_commit - commit a reserved | |
1348 | * @buffer: The buffer to commit to | |
1349 | * @event: The event pointer to commit. | |
1350 | * @flags: the interrupt flags received from ring_buffer_lock_reserve. | |
1351 | * | |
1352 | * This commits the data to the ring buffer, and releases any locks held. | |
1353 | * | |
1354 | * Must be paired with ring_buffer_lock_reserve. | |
1355 | */ | |
1356 | int ring_buffer_unlock_commit(struct ring_buffer *buffer, | |
1357 | struct ring_buffer_event *event, | |
1358 | unsigned long flags) | |
1359 | { | |
1360 | struct ring_buffer_per_cpu *cpu_buffer; | |
1361 | int cpu = raw_smp_processor_id(); | |
1362 | ||
1363 | cpu_buffer = buffer->buffers[cpu]; | |
1364 | ||
7a8e76a3 SR |
1365 | rb_commit(cpu_buffer, event); |
1366 | ||
bf41a158 SR |
1367 | /* |
1368 | * Only the last preempt count needs to restore preemption. | |
1369 | */ | |
182e9f5f SR |
1370 | if (preempt_count() == 1) |
1371 | ftrace_preempt_enable(per_cpu(rb_need_resched, cpu)); | |
1372 | else | |
bf41a158 | 1373 | preempt_enable_no_resched_notrace(); |
7a8e76a3 SR |
1374 | |
1375 | return 0; | |
1376 | } | |
c4f50183 | 1377 | EXPORT_SYMBOL_GPL(ring_buffer_unlock_commit); |
7a8e76a3 SR |
1378 | |
1379 | /** | |
1380 | * ring_buffer_write - write data to the buffer without reserving | |
1381 | * @buffer: The ring buffer to write to. | |
1382 | * @length: The length of the data being written (excluding the event header) | |
1383 | * @data: The data to write to the buffer. | |
1384 | * | |
1385 | * This is like ring_buffer_lock_reserve and ring_buffer_unlock_commit as | |
1386 | * one function. If you already have the data to write to the buffer, it | |
1387 | * may be easier to simply call this function. | |
1388 | * | |
1389 | * Note, like ring_buffer_lock_reserve, the length is the length of the data | |
1390 | * and not the length of the event which would hold the header. | |
1391 | */ | |
1392 | int ring_buffer_write(struct ring_buffer *buffer, | |
1393 | unsigned long length, | |
1394 | void *data) | |
1395 | { | |
1396 | struct ring_buffer_per_cpu *cpu_buffer; | |
1397 | struct ring_buffer_event *event; | |
bf41a158 | 1398 | unsigned long event_length; |
7a8e76a3 SR |
1399 | void *body; |
1400 | int ret = -EBUSY; | |
bf41a158 | 1401 | int cpu, resched; |
7a8e76a3 | 1402 | |
033601a3 | 1403 | if (ring_buffer_flags != RB_BUFFERS_ON) |
a3583244 SR |
1404 | return -EBUSY; |
1405 | ||
7a8e76a3 SR |
1406 | if (atomic_read(&buffer->record_disabled)) |
1407 | return -EBUSY; | |
1408 | ||
182e9f5f | 1409 | resched = ftrace_preempt_disable(); |
bf41a158 | 1410 | |
7a8e76a3 SR |
1411 | cpu = raw_smp_processor_id(); |
1412 | ||
9e01c1b7 | 1413 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
d769041f | 1414 | goto out; |
7a8e76a3 SR |
1415 | |
1416 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 SR |
1417 | |
1418 | if (atomic_read(&cpu_buffer->record_disabled)) | |
1419 | goto out; | |
1420 | ||
1421 | event_length = rb_calculate_event_length(length); | |
1422 | event = rb_reserve_next_event(cpu_buffer, | |
1423 | RINGBUF_TYPE_DATA, event_length); | |
1424 | if (!event) | |
1425 | goto out; | |
1426 | ||
1427 | body = rb_event_data(event); | |
1428 | ||
1429 | memcpy(body, data, length); | |
1430 | ||
1431 | rb_commit(cpu_buffer, event); | |
1432 | ||
1433 | ret = 0; | |
1434 | out: | |
182e9f5f | 1435 | ftrace_preempt_enable(resched); |
7a8e76a3 SR |
1436 | |
1437 | return ret; | |
1438 | } | |
c4f50183 | 1439 | EXPORT_SYMBOL_GPL(ring_buffer_write); |
7a8e76a3 | 1440 | |
bf41a158 SR |
1441 | static inline int rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) |
1442 | { | |
1443 | struct buffer_page *reader = cpu_buffer->reader_page; | |
1444 | struct buffer_page *head = cpu_buffer->head_page; | |
1445 | struct buffer_page *commit = cpu_buffer->commit_page; | |
1446 | ||
1447 | return reader->read == rb_page_commit(reader) && | |
1448 | (commit == reader || | |
1449 | (commit == head && | |
1450 | head->read == rb_page_commit(commit))); | |
1451 | } | |
1452 | ||
7a8e76a3 SR |
1453 | /** |
1454 | * ring_buffer_record_disable - stop all writes into the buffer | |
1455 | * @buffer: The ring buffer to stop writes to. | |
1456 | * | |
1457 | * This prevents all writes to the buffer. Any attempt to write | |
1458 | * to the buffer after this will fail and return NULL. | |
1459 | * | |
1460 | * The caller should call synchronize_sched() after this. | |
1461 | */ | |
1462 | void ring_buffer_record_disable(struct ring_buffer *buffer) | |
1463 | { | |
1464 | atomic_inc(&buffer->record_disabled); | |
1465 | } | |
c4f50183 | 1466 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable); |
7a8e76a3 SR |
1467 | |
1468 | /** | |
1469 | * ring_buffer_record_enable - enable writes to the buffer | |
1470 | * @buffer: The ring buffer to enable writes | |
1471 | * | |
1472 | * Note, multiple disables will need the same number of enables | |
1473 | * to truely enable the writing (much like preempt_disable). | |
1474 | */ | |
1475 | void ring_buffer_record_enable(struct ring_buffer *buffer) | |
1476 | { | |
1477 | atomic_dec(&buffer->record_disabled); | |
1478 | } | |
c4f50183 | 1479 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable); |
7a8e76a3 SR |
1480 | |
1481 | /** | |
1482 | * ring_buffer_record_disable_cpu - stop all writes into the cpu_buffer | |
1483 | * @buffer: The ring buffer to stop writes to. | |
1484 | * @cpu: The CPU buffer to stop | |
1485 | * | |
1486 | * This prevents all writes to the buffer. Any attempt to write | |
1487 | * to the buffer after this will fail and return NULL. | |
1488 | * | |
1489 | * The caller should call synchronize_sched() after this. | |
1490 | */ | |
1491 | void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu) | |
1492 | { | |
1493 | struct ring_buffer_per_cpu *cpu_buffer; | |
1494 | ||
9e01c1b7 | 1495 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
7a8e76a3 SR |
1496 | return; |
1497 | ||
1498 | cpu_buffer = buffer->buffers[cpu]; | |
1499 | atomic_inc(&cpu_buffer->record_disabled); | |
1500 | } | |
c4f50183 | 1501 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable_cpu); |
7a8e76a3 SR |
1502 | |
1503 | /** | |
1504 | * ring_buffer_record_enable_cpu - enable writes to the buffer | |
1505 | * @buffer: The ring buffer to enable writes | |
1506 | * @cpu: The CPU to enable. | |
1507 | * | |
1508 | * Note, multiple disables will need the same number of enables | |
1509 | * to truely enable the writing (much like preempt_disable). | |
1510 | */ | |
1511 | void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu) | |
1512 | { | |
1513 | struct ring_buffer_per_cpu *cpu_buffer; | |
1514 | ||
9e01c1b7 | 1515 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
7a8e76a3 SR |
1516 | return; |
1517 | ||
1518 | cpu_buffer = buffer->buffers[cpu]; | |
1519 | atomic_dec(&cpu_buffer->record_disabled); | |
1520 | } | |
c4f50183 | 1521 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu); |
7a8e76a3 SR |
1522 | |
1523 | /** | |
1524 | * ring_buffer_entries_cpu - get the number of entries in a cpu buffer | |
1525 | * @buffer: The ring buffer | |
1526 | * @cpu: The per CPU buffer to get the entries from. | |
1527 | */ | |
1528 | unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu) | |
1529 | { | |
1530 | struct ring_buffer_per_cpu *cpu_buffer; | |
1531 | ||
9e01c1b7 | 1532 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
7a8e76a3 SR |
1533 | return 0; |
1534 | ||
1535 | cpu_buffer = buffer->buffers[cpu]; | |
1536 | return cpu_buffer->entries; | |
1537 | } | |
c4f50183 | 1538 | EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu); |
7a8e76a3 SR |
1539 | |
1540 | /** | |
1541 | * ring_buffer_overrun_cpu - get the number of overruns in a cpu_buffer | |
1542 | * @buffer: The ring buffer | |
1543 | * @cpu: The per CPU buffer to get the number of overruns from | |
1544 | */ | |
1545 | unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu) | |
1546 | { | |
1547 | struct ring_buffer_per_cpu *cpu_buffer; | |
1548 | ||
9e01c1b7 | 1549 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
7a8e76a3 SR |
1550 | return 0; |
1551 | ||
1552 | cpu_buffer = buffer->buffers[cpu]; | |
1553 | return cpu_buffer->overrun; | |
1554 | } | |
c4f50183 | 1555 | EXPORT_SYMBOL_GPL(ring_buffer_overrun_cpu); |
7a8e76a3 SR |
1556 | |
1557 | /** | |
1558 | * ring_buffer_entries - get the number of entries in a buffer | |
1559 | * @buffer: The ring buffer | |
1560 | * | |
1561 | * Returns the total number of entries in the ring buffer | |
1562 | * (all CPU entries) | |
1563 | */ | |
1564 | unsigned long ring_buffer_entries(struct ring_buffer *buffer) | |
1565 | { | |
1566 | struct ring_buffer_per_cpu *cpu_buffer; | |
1567 | unsigned long entries = 0; | |
1568 | int cpu; | |
1569 | ||
1570 | /* if you care about this being correct, lock the buffer */ | |
1571 | for_each_buffer_cpu(buffer, cpu) { | |
1572 | cpu_buffer = buffer->buffers[cpu]; | |
1573 | entries += cpu_buffer->entries; | |
1574 | } | |
1575 | ||
1576 | return entries; | |
1577 | } | |
c4f50183 | 1578 | EXPORT_SYMBOL_GPL(ring_buffer_entries); |
7a8e76a3 SR |
1579 | |
1580 | /** | |
1581 | * ring_buffer_overrun_cpu - get the number of overruns in buffer | |
1582 | * @buffer: The ring buffer | |
1583 | * | |
1584 | * Returns the total number of overruns in the ring buffer | |
1585 | * (all CPU entries) | |
1586 | */ | |
1587 | unsigned long ring_buffer_overruns(struct ring_buffer *buffer) | |
1588 | { | |
1589 | struct ring_buffer_per_cpu *cpu_buffer; | |
1590 | unsigned long overruns = 0; | |
1591 | int cpu; | |
1592 | ||
1593 | /* if you care about this being correct, lock the buffer */ | |
1594 | for_each_buffer_cpu(buffer, cpu) { | |
1595 | cpu_buffer = buffer->buffers[cpu]; | |
1596 | overruns += cpu_buffer->overrun; | |
1597 | } | |
1598 | ||
1599 | return overruns; | |
1600 | } | |
c4f50183 | 1601 | EXPORT_SYMBOL_GPL(ring_buffer_overruns); |
7a8e76a3 | 1602 | |
642edba5 | 1603 | static void rb_iter_reset(struct ring_buffer_iter *iter) |
7a8e76a3 SR |
1604 | { |
1605 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
1606 | ||
d769041f SR |
1607 | /* Iterator usage is expected to have record disabled */ |
1608 | if (list_empty(&cpu_buffer->reader_page->list)) { | |
1609 | iter->head_page = cpu_buffer->head_page; | |
6f807acd | 1610 | iter->head = cpu_buffer->head_page->read; |
d769041f SR |
1611 | } else { |
1612 | iter->head_page = cpu_buffer->reader_page; | |
6f807acd | 1613 | iter->head = cpu_buffer->reader_page->read; |
d769041f SR |
1614 | } |
1615 | if (iter->head) | |
1616 | iter->read_stamp = cpu_buffer->read_stamp; | |
1617 | else | |
abc9b56d | 1618 | iter->read_stamp = iter->head_page->page->time_stamp; |
642edba5 | 1619 | } |
f83c9d0f | 1620 | |
642edba5 SR |
1621 | /** |
1622 | * ring_buffer_iter_reset - reset an iterator | |
1623 | * @iter: The iterator to reset | |
1624 | * | |
1625 | * Resets the iterator, so that it will start from the beginning | |
1626 | * again. | |
1627 | */ | |
1628 | void ring_buffer_iter_reset(struct ring_buffer_iter *iter) | |
1629 | { | |
1630 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
1631 | unsigned long flags; | |
1632 | ||
1633 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
1634 | rb_iter_reset(iter); | |
f83c9d0f | 1635 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
7a8e76a3 | 1636 | } |
c4f50183 | 1637 | EXPORT_SYMBOL_GPL(ring_buffer_iter_reset); |
7a8e76a3 SR |
1638 | |
1639 | /** | |
1640 | * ring_buffer_iter_empty - check if an iterator has no more to read | |
1641 | * @iter: The iterator to check | |
1642 | */ | |
1643 | int ring_buffer_iter_empty(struct ring_buffer_iter *iter) | |
1644 | { | |
1645 | struct ring_buffer_per_cpu *cpu_buffer; | |
1646 | ||
1647 | cpu_buffer = iter->cpu_buffer; | |
1648 | ||
bf41a158 SR |
1649 | return iter->head_page == cpu_buffer->commit_page && |
1650 | iter->head == rb_commit_index(cpu_buffer); | |
7a8e76a3 | 1651 | } |
c4f50183 | 1652 | EXPORT_SYMBOL_GPL(ring_buffer_iter_empty); |
7a8e76a3 SR |
1653 | |
1654 | static void | |
1655 | rb_update_read_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
1656 | struct ring_buffer_event *event) | |
1657 | { | |
1658 | u64 delta; | |
1659 | ||
1660 | switch (event->type) { | |
1661 | case RINGBUF_TYPE_PADDING: | |
1662 | return; | |
1663 | ||
1664 | case RINGBUF_TYPE_TIME_EXTEND: | |
1665 | delta = event->array[0]; | |
1666 | delta <<= TS_SHIFT; | |
1667 | delta += event->time_delta; | |
1668 | cpu_buffer->read_stamp += delta; | |
1669 | return; | |
1670 | ||
1671 | case RINGBUF_TYPE_TIME_STAMP: | |
1672 | /* FIXME: not implemented */ | |
1673 | return; | |
1674 | ||
1675 | case RINGBUF_TYPE_DATA: | |
1676 | cpu_buffer->read_stamp += event->time_delta; | |
1677 | return; | |
1678 | ||
1679 | default: | |
1680 | BUG(); | |
1681 | } | |
1682 | return; | |
1683 | } | |
1684 | ||
1685 | static void | |
1686 | rb_update_iter_read_stamp(struct ring_buffer_iter *iter, | |
1687 | struct ring_buffer_event *event) | |
1688 | { | |
1689 | u64 delta; | |
1690 | ||
1691 | switch (event->type) { | |
1692 | case RINGBUF_TYPE_PADDING: | |
1693 | return; | |
1694 | ||
1695 | case RINGBUF_TYPE_TIME_EXTEND: | |
1696 | delta = event->array[0]; | |
1697 | delta <<= TS_SHIFT; | |
1698 | delta += event->time_delta; | |
1699 | iter->read_stamp += delta; | |
1700 | return; | |
1701 | ||
1702 | case RINGBUF_TYPE_TIME_STAMP: | |
1703 | /* FIXME: not implemented */ | |
1704 | return; | |
1705 | ||
1706 | case RINGBUF_TYPE_DATA: | |
1707 | iter->read_stamp += event->time_delta; | |
1708 | return; | |
1709 | ||
1710 | default: | |
1711 | BUG(); | |
1712 | } | |
1713 | return; | |
1714 | } | |
1715 | ||
d769041f SR |
1716 | static struct buffer_page * |
1717 | rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) | |
7a8e76a3 | 1718 | { |
d769041f SR |
1719 | struct buffer_page *reader = NULL; |
1720 | unsigned long flags; | |
818e3dd3 | 1721 | int nr_loops = 0; |
d769041f | 1722 | |
3e03fb7f SR |
1723 | local_irq_save(flags); |
1724 | __raw_spin_lock(&cpu_buffer->lock); | |
d769041f SR |
1725 | |
1726 | again: | |
818e3dd3 SR |
1727 | /* |
1728 | * This should normally only loop twice. But because the | |
1729 | * start of the reader inserts an empty page, it causes | |
1730 | * a case where we will loop three times. There should be no | |
1731 | * reason to loop four times (that I know of). | |
1732 | */ | |
3e89c7bb | 1733 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 3)) { |
818e3dd3 SR |
1734 | reader = NULL; |
1735 | goto out; | |
1736 | } | |
1737 | ||
d769041f SR |
1738 | reader = cpu_buffer->reader_page; |
1739 | ||
1740 | /* If there's more to read, return this page */ | |
bf41a158 | 1741 | if (cpu_buffer->reader_page->read < rb_page_size(reader)) |
d769041f SR |
1742 | goto out; |
1743 | ||
1744 | /* Never should we have an index greater than the size */ | |
3e89c7bb SR |
1745 | if (RB_WARN_ON(cpu_buffer, |
1746 | cpu_buffer->reader_page->read > rb_page_size(reader))) | |
1747 | goto out; | |
d769041f SR |
1748 | |
1749 | /* check if we caught up to the tail */ | |
1750 | reader = NULL; | |
bf41a158 | 1751 | if (cpu_buffer->commit_page == cpu_buffer->reader_page) |
d769041f | 1752 | goto out; |
7a8e76a3 SR |
1753 | |
1754 | /* | |
d769041f SR |
1755 | * Splice the empty reader page into the list around the head. |
1756 | * Reset the reader page to size zero. | |
7a8e76a3 | 1757 | */ |
7a8e76a3 | 1758 | |
d769041f SR |
1759 | reader = cpu_buffer->head_page; |
1760 | cpu_buffer->reader_page->list.next = reader->list.next; | |
1761 | cpu_buffer->reader_page->list.prev = reader->list.prev; | |
bf41a158 SR |
1762 | |
1763 | local_set(&cpu_buffer->reader_page->write, 0); | |
abc9b56d | 1764 | local_set(&cpu_buffer->reader_page->page->commit, 0); |
7a8e76a3 | 1765 | |
d769041f SR |
1766 | /* Make the reader page now replace the head */ |
1767 | reader->list.prev->next = &cpu_buffer->reader_page->list; | |
1768 | reader->list.next->prev = &cpu_buffer->reader_page->list; | |
7a8e76a3 SR |
1769 | |
1770 | /* | |
d769041f SR |
1771 | * If the tail is on the reader, then we must set the head |
1772 | * to the inserted page, otherwise we set it one before. | |
7a8e76a3 | 1773 | */ |
d769041f | 1774 | cpu_buffer->head_page = cpu_buffer->reader_page; |
7a8e76a3 | 1775 | |
bf41a158 | 1776 | if (cpu_buffer->commit_page != reader) |
d769041f SR |
1777 | rb_inc_page(cpu_buffer, &cpu_buffer->head_page); |
1778 | ||
1779 | /* Finally update the reader page to the new head */ | |
1780 | cpu_buffer->reader_page = reader; | |
1781 | rb_reset_reader_page(cpu_buffer); | |
1782 | ||
1783 | goto again; | |
1784 | ||
1785 | out: | |
3e03fb7f SR |
1786 | __raw_spin_unlock(&cpu_buffer->lock); |
1787 | local_irq_restore(flags); | |
d769041f SR |
1788 | |
1789 | return reader; | |
1790 | } | |
1791 | ||
1792 | static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer) | |
1793 | { | |
1794 | struct ring_buffer_event *event; | |
1795 | struct buffer_page *reader; | |
1796 | unsigned length; | |
1797 | ||
1798 | reader = rb_get_reader_page(cpu_buffer); | |
7a8e76a3 | 1799 | |
d769041f | 1800 | /* This function should not be called when buffer is empty */ |
3e89c7bb SR |
1801 | if (RB_WARN_ON(cpu_buffer, !reader)) |
1802 | return; | |
7a8e76a3 | 1803 | |
d769041f SR |
1804 | event = rb_reader_event(cpu_buffer); |
1805 | ||
1806 | if (event->type == RINGBUF_TYPE_DATA) | |
1807 | cpu_buffer->entries--; | |
1808 | ||
1809 | rb_update_read_stamp(cpu_buffer, event); | |
1810 | ||
1811 | length = rb_event_length(event); | |
6f807acd | 1812 | cpu_buffer->reader_page->read += length; |
7a8e76a3 SR |
1813 | } |
1814 | ||
1815 | static void rb_advance_iter(struct ring_buffer_iter *iter) | |
1816 | { | |
1817 | struct ring_buffer *buffer; | |
1818 | struct ring_buffer_per_cpu *cpu_buffer; | |
1819 | struct ring_buffer_event *event; | |
1820 | unsigned length; | |
1821 | ||
1822 | cpu_buffer = iter->cpu_buffer; | |
1823 | buffer = cpu_buffer->buffer; | |
1824 | ||
1825 | /* | |
1826 | * Check if we are at the end of the buffer. | |
1827 | */ | |
bf41a158 | 1828 | if (iter->head >= rb_page_size(iter->head_page)) { |
3e89c7bb SR |
1829 | if (RB_WARN_ON(buffer, |
1830 | iter->head_page == cpu_buffer->commit_page)) | |
1831 | return; | |
d769041f | 1832 | rb_inc_iter(iter); |
7a8e76a3 SR |
1833 | return; |
1834 | } | |
1835 | ||
1836 | event = rb_iter_head_event(iter); | |
1837 | ||
1838 | length = rb_event_length(event); | |
1839 | ||
1840 | /* | |
1841 | * This should not be called to advance the header if we are | |
1842 | * at the tail of the buffer. | |
1843 | */ | |
3e89c7bb | 1844 | if (RB_WARN_ON(cpu_buffer, |
f536aafc | 1845 | (iter->head_page == cpu_buffer->commit_page) && |
3e89c7bb SR |
1846 | (iter->head + length > rb_commit_index(cpu_buffer)))) |
1847 | return; | |
7a8e76a3 SR |
1848 | |
1849 | rb_update_iter_read_stamp(iter, event); | |
1850 | ||
1851 | iter->head += length; | |
1852 | ||
1853 | /* check for end of page padding */ | |
bf41a158 SR |
1854 | if ((iter->head >= rb_page_size(iter->head_page)) && |
1855 | (iter->head_page != cpu_buffer->commit_page)) | |
7a8e76a3 SR |
1856 | rb_advance_iter(iter); |
1857 | } | |
1858 | ||
f83c9d0f SR |
1859 | static struct ring_buffer_event * |
1860 | rb_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) | |
7a8e76a3 SR |
1861 | { |
1862 | struct ring_buffer_per_cpu *cpu_buffer; | |
1863 | struct ring_buffer_event *event; | |
d769041f | 1864 | struct buffer_page *reader; |
818e3dd3 | 1865 | int nr_loops = 0; |
7a8e76a3 | 1866 | |
9e01c1b7 | 1867 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
7a8e76a3 SR |
1868 | return NULL; |
1869 | ||
1870 | cpu_buffer = buffer->buffers[cpu]; | |
1871 | ||
1872 | again: | |
818e3dd3 SR |
1873 | /* |
1874 | * We repeat when a timestamp is encountered. It is possible | |
1875 | * to get multiple timestamps from an interrupt entering just | |
1876 | * as one timestamp is about to be written. The max times | |
1877 | * that this can happen is the number of nested interrupts we | |
1878 | * can have. Nesting 10 deep of interrupts is clearly | |
1879 | * an anomaly. | |
1880 | */ | |
3e89c7bb | 1881 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 10)) |
818e3dd3 | 1882 | return NULL; |
818e3dd3 | 1883 | |
d769041f SR |
1884 | reader = rb_get_reader_page(cpu_buffer); |
1885 | if (!reader) | |
7a8e76a3 SR |
1886 | return NULL; |
1887 | ||
d769041f | 1888 | event = rb_reader_event(cpu_buffer); |
7a8e76a3 SR |
1889 | |
1890 | switch (event->type) { | |
1891 | case RINGBUF_TYPE_PADDING: | |
bf41a158 | 1892 | RB_WARN_ON(cpu_buffer, 1); |
d769041f SR |
1893 | rb_advance_reader(cpu_buffer); |
1894 | return NULL; | |
7a8e76a3 SR |
1895 | |
1896 | case RINGBUF_TYPE_TIME_EXTEND: | |
1897 | /* Internal data, OK to advance */ | |
d769041f | 1898 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
1899 | goto again; |
1900 | ||
1901 | case RINGBUF_TYPE_TIME_STAMP: | |
1902 | /* FIXME: not implemented */ | |
d769041f | 1903 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
1904 | goto again; |
1905 | ||
1906 | case RINGBUF_TYPE_DATA: | |
1907 | if (ts) { | |
1908 | *ts = cpu_buffer->read_stamp + event->time_delta; | |
1909 | ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts); | |
1910 | } | |
1911 | return event; | |
1912 | ||
1913 | default: | |
1914 | BUG(); | |
1915 | } | |
1916 | ||
1917 | return NULL; | |
1918 | } | |
c4f50183 | 1919 | EXPORT_SYMBOL_GPL(ring_buffer_peek); |
7a8e76a3 | 1920 | |
f83c9d0f SR |
1921 | static struct ring_buffer_event * |
1922 | rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) | |
7a8e76a3 SR |
1923 | { |
1924 | struct ring_buffer *buffer; | |
1925 | struct ring_buffer_per_cpu *cpu_buffer; | |
1926 | struct ring_buffer_event *event; | |
818e3dd3 | 1927 | int nr_loops = 0; |
7a8e76a3 SR |
1928 | |
1929 | if (ring_buffer_iter_empty(iter)) | |
1930 | return NULL; | |
1931 | ||
1932 | cpu_buffer = iter->cpu_buffer; | |
1933 | buffer = cpu_buffer->buffer; | |
1934 | ||
1935 | again: | |
818e3dd3 SR |
1936 | /* |
1937 | * We repeat when a timestamp is encountered. It is possible | |
1938 | * to get multiple timestamps from an interrupt entering just | |
1939 | * as one timestamp is about to be written. The max times | |
1940 | * that this can happen is the number of nested interrupts we | |
1941 | * can have. Nesting 10 deep of interrupts is clearly | |
1942 | * an anomaly. | |
1943 | */ | |
3e89c7bb | 1944 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 10)) |
818e3dd3 | 1945 | return NULL; |
818e3dd3 | 1946 | |
7a8e76a3 SR |
1947 | if (rb_per_cpu_empty(cpu_buffer)) |
1948 | return NULL; | |
1949 | ||
1950 | event = rb_iter_head_event(iter); | |
1951 | ||
1952 | switch (event->type) { | |
1953 | case RINGBUF_TYPE_PADDING: | |
d769041f | 1954 | rb_inc_iter(iter); |
7a8e76a3 SR |
1955 | goto again; |
1956 | ||
1957 | case RINGBUF_TYPE_TIME_EXTEND: | |
1958 | /* Internal data, OK to advance */ | |
1959 | rb_advance_iter(iter); | |
1960 | goto again; | |
1961 | ||
1962 | case RINGBUF_TYPE_TIME_STAMP: | |
1963 | /* FIXME: not implemented */ | |
1964 | rb_advance_iter(iter); | |
1965 | goto again; | |
1966 | ||
1967 | case RINGBUF_TYPE_DATA: | |
1968 | if (ts) { | |
1969 | *ts = iter->read_stamp + event->time_delta; | |
1970 | ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts); | |
1971 | } | |
1972 | return event; | |
1973 | ||
1974 | default: | |
1975 | BUG(); | |
1976 | } | |
1977 | ||
1978 | return NULL; | |
1979 | } | |
c4f50183 | 1980 | EXPORT_SYMBOL_GPL(ring_buffer_iter_peek); |
7a8e76a3 | 1981 | |
f83c9d0f SR |
1982 | /** |
1983 | * ring_buffer_peek - peek at the next event to be read | |
1984 | * @buffer: The ring buffer to read | |
1985 | * @cpu: The cpu to peak at | |
1986 | * @ts: The timestamp counter of this event. | |
1987 | * | |
1988 | * This will return the event that will be read next, but does | |
1989 | * not consume the data. | |
1990 | */ | |
1991 | struct ring_buffer_event * | |
1992 | ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) | |
1993 | { | |
1994 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
1995 | struct ring_buffer_event *event; | |
1996 | unsigned long flags; | |
1997 | ||
1998 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
1999 | event = rb_buffer_peek(buffer, cpu, ts); | |
2000 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
2001 | ||
2002 | return event; | |
2003 | } | |
2004 | ||
2005 | /** | |
2006 | * ring_buffer_iter_peek - peek at the next event to be read | |
2007 | * @iter: The ring buffer iterator | |
2008 | * @ts: The timestamp counter of this event. | |
2009 | * | |
2010 | * This will return the event that will be read next, but does | |
2011 | * not increment the iterator. | |
2012 | */ | |
2013 | struct ring_buffer_event * | |
2014 | ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) | |
2015 | { | |
2016 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
2017 | struct ring_buffer_event *event; | |
2018 | unsigned long flags; | |
2019 | ||
2020 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
2021 | event = rb_iter_peek(iter, ts); | |
2022 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
2023 | ||
2024 | return event; | |
2025 | } | |
2026 | ||
7a8e76a3 SR |
2027 | /** |
2028 | * ring_buffer_consume - return an event and consume it | |
2029 | * @buffer: The ring buffer to get the next event from | |
2030 | * | |
2031 | * Returns the next event in the ring buffer, and that event is consumed. | |
2032 | * Meaning, that sequential reads will keep returning a different event, | |
2033 | * and eventually empty the ring buffer if the producer is slower. | |
2034 | */ | |
2035 | struct ring_buffer_event * | |
2036 | ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts) | |
2037 | { | |
f83c9d0f | 2038 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; |
7a8e76a3 | 2039 | struct ring_buffer_event *event; |
f83c9d0f | 2040 | unsigned long flags; |
7a8e76a3 | 2041 | |
9e01c1b7 | 2042 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
7a8e76a3 SR |
2043 | return NULL; |
2044 | ||
f83c9d0f SR |
2045 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
2046 | ||
2047 | event = rb_buffer_peek(buffer, cpu, ts); | |
7a8e76a3 | 2048 | if (!event) |
f83c9d0f | 2049 | goto out; |
7a8e76a3 | 2050 | |
d769041f | 2051 | rb_advance_reader(cpu_buffer); |
7a8e76a3 | 2052 | |
f83c9d0f SR |
2053 | out: |
2054 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
2055 | ||
7a8e76a3 SR |
2056 | return event; |
2057 | } | |
c4f50183 | 2058 | EXPORT_SYMBOL_GPL(ring_buffer_consume); |
7a8e76a3 SR |
2059 | |
2060 | /** | |
2061 | * ring_buffer_read_start - start a non consuming read of the buffer | |
2062 | * @buffer: The ring buffer to read from | |
2063 | * @cpu: The cpu buffer to iterate over | |
2064 | * | |
2065 | * This starts up an iteration through the buffer. It also disables | |
2066 | * the recording to the buffer until the reading is finished. | |
2067 | * This prevents the reading from being corrupted. This is not | |
2068 | * a consuming read, so a producer is not expected. | |
2069 | * | |
2070 | * Must be paired with ring_buffer_finish. | |
2071 | */ | |
2072 | struct ring_buffer_iter * | |
2073 | ring_buffer_read_start(struct ring_buffer *buffer, int cpu) | |
2074 | { | |
2075 | struct ring_buffer_per_cpu *cpu_buffer; | |
2076 | struct ring_buffer_iter *iter; | |
d769041f | 2077 | unsigned long flags; |
7a8e76a3 | 2078 | |
9e01c1b7 | 2079 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
7a8e76a3 SR |
2080 | return NULL; |
2081 | ||
2082 | iter = kmalloc(sizeof(*iter), GFP_KERNEL); | |
2083 | if (!iter) | |
2084 | return NULL; | |
2085 | ||
2086 | cpu_buffer = buffer->buffers[cpu]; | |
2087 | ||
2088 | iter->cpu_buffer = cpu_buffer; | |
2089 | ||
2090 | atomic_inc(&cpu_buffer->record_disabled); | |
2091 | synchronize_sched(); | |
2092 | ||
f83c9d0f | 2093 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
3e03fb7f | 2094 | __raw_spin_lock(&cpu_buffer->lock); |
642edba5 | 2095 | rb_iter_reset(iter); |
3e03fb7f | 2096 | __raw_spin_unlock(&cpu_buffer->lock); |
f83c9d0f | 2097 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
7a8e76a3 SR |
2098 | |
2099 | return iter; | |
2100 | } | |
c4f50183 | 2101 | EXPORT_SYMBOL_GPL(ring_buffer_read_start); |
7a8e76a3 SR |
2102 | |
2103 | /** | |
2104 | * ring_buffer_finish - finish reading the iterator of the buffer | |
2105 | * @iter: The iterator retrieved by ring_buffer_start | |
2106 | * | |
2107 | * This re-enables the recording to the buffer, and frees the | |
2108 | * iterator. | |
2109 | */ | |
2110 | void | |
2111 | ring_buffer_read_finish(struct ring_buffer_iter *iter) | |
2112 | { | |
2113 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
2114 | ||
2115 | atomic_dec(&cpu_buffer->record_disabled); | |
2116 | kfree(iter); | |
2117 | } | |
c4f50183 | 2118 | EXPORT_SYMBOL_GPL(ring_buffer_read_finish); |
7a8e76a3 SR |
2119 | |
2120 | /** | |
2121 | * ring_buffer_read - read the next item in the ring buffer by the iterator | |
2122 | * @iter: The ring buffer iterator | |
2123 | * @ts: The time stamp of the event read. | |
2124 | * | |
2125 | * This reads the next event in the ring buffer and increments the iterator. | |
2126 | */ | |
2127 | struct ring_buffer_event * | |
2128 | ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) | |
2129 | { | |
2130 | struct ring_buffer_event *event; | |
f83c9d0f SR |
2131 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
2132 | unsigned long flags; | |
7a8e76a3 | 2133 | |
f83c9d0f SR |
2134 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
2135 | event = rb_iter_peek(iter, ts); | |
7a8e76a3 | 2136 | if (!event) |
f83c9d0f | 2137 | goto out; |
7a8e76a3 SR |
2138 | |
2139 | rb_advance_iter(iter); | |
f83c9d0f SR |
2140 | out: |
2141 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
7a8e76a3 SR |
2142 | |
2143 | return event; | |
2144 | } | |
c4f50183 | 2145 | EXPORT_SYMBOL_GPL(ring_buffer_read); |
7a8e76a3 SR |
2146 | |
2147 | /** | |
2148 | * ring_buffer_size - return the size of the ring buffer (in bytes) | |
2149 | * @buffer: The ring buffer. | |
2150 | */ | |
2151 | unsigned long ring_buffer_size(struct ring_buffer *buffer) | |
2152 | { | |
2153 | return BUF_PAGE_SIZE * buffer->pages; | |
2154 | } | |
c4f50183 | 2155 | EXPORT_SYMBOL_GPL(ring_buffer_size); |
7a8e76a3 SR |
2156 | |
2157 | static void | |
2158 | rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) | |
2159 | { | |
2160 | cpu_buffer->head_page | |
2161 | = list_entry(cpu_buffer->pages.next, struct buffer_page, list); | |
bf41a158 | 2162 | local_set(&cpu_buffer->head_page->write, 0); |
abc9b56d | 2163 | local_set(&cpu_buffer->head_page->page->commit, 0); |
d769041f | 2164 | |
6f807acd | 2165 | cpu_buffer->head_page->read = 0; |
bf41a158 SR |
2166 | |
2167 | cpu_buffer->tail_page = cpu_buffer->head_page; | |
2168 | cpu_buffer->commit_page = cpu_buffer->head_page; | |
2169 | ||
2170 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); | |
2171 | local_set(&cpu_buffer->reader_page->write, 0); | |
abc9b56d | 2172 | local_set(&cpu_buffer->reader_page->page->commit, 0); |
6f807acd | 2173 | cpu_buffer->reader_page->read = 0; |
7a8e76a3 | 2174 | |
7a8e76a3 SR |
2175 | cpu_buffer->overrun = 0; |
2176 | cpu_buffer->entries = 0; | |
91a8d07d SR |
2177 | |
2178 | cpu_buffer->write_stamp = 0; | |
2179 | cpu_buffer->read_stamp = 0; | |
7a8e76a3 SR |
2180 | } |
2181 | ||
2182 | /** | |
2183 | * ring_buffer_reset_cpu - reset a ring buffer per CPU buffer | |
2184 | * @buffer: The ring buffer to reset a per cpu buffer of | |
2185 | * @cpu: The CPU buffer to be reset | |
2186 | */ | |
2187 | void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) | |
2188 | { | |
2189 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
2190 | unsigned long flags; | |
2191 | ||
9e01c1b7 | 2192 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
7a8e76a3 SR |
2193 | return; |
2194 | ||
f83c9d0f SR |
2195 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
2196 | ||
3e03fb7f | 2197 | __raw_spin_lock(&cpu_buffer->lock); |
7a8e76a3 SR |
2198 | |
2199 | rb_reset_cpu(cpu_buffer); | |
2200 | ||
3e03fb7f | 2201 | __raw_spin_unlock(&cpu_buffer->lock); |
f83c9d0f SR |
2202 | |
2203 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
7a8e76a3 | 2204 | } |
c4f50183 | 2205 | EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); |
7a8e76a3 SR |
2206 | |
2207 | /** | |
2208 | * ring_buffer_reset - reset a ring buffer | |
2209 | * @buffer: The ring buffer to reset all cpu buffers | |
2210 | */ | |
2211 | void ring_buffer_reset(struct ring_buffer *buffer) | |
2212 | { | |
7a8e76a3 SR |
2213 | int cpu; |
2214 | ||
7a8e76a3 | 2215 | for_each_buffer_cpu(buffer, cpu) |
d769041f | 2216 | ring_buffer_reset_cpu(buffer, cpu); |
7a8e76a3 | 2217 | } |
c4f50183 | 2218 | EXPORT_SYMBOL_GPL(ring_buffer_reset); |
7a8e76a3 SR |
2219 | |
2220 | /** | |
2221 | * rind_buffer_empty - is the ring buffer empty? | |
2222 | * @buffer: The ring buffer to test | |
2223 | */ | |
2224 | int ring_buffer_empty(struct ring_buffer *buffer) | |
2225 | { | |
2226 | struct ring_buffer_per_cpu *cpu_buffer; | |
2227 | int cpu; | |
2228 | ||
2229 | /* yes this is racy, but if you don't like the race, lock the buffer */ | |
2230 | for_each_buffer_cpu(buffer, cpu) { | |
2231 | cpu_buffer = buffer->buffers[cpu]; | |
2232 | if (!rb_per_cpu_empty(cpu_buffer)) | |
2233 | return 0; | |
2234 | } | |
2235 | return 1; | |
2236 | } | |
c4f50183 | 2237 | EXPORT_SYMBOL_GPL(ring_buffer_empty); |
7a8e76a3 SR |
2238 | |
2239 | /** | |
2240 | * ring_buffer_empty_cpu - is a cpu buffer of a ring buffer empty? | |
2241 | * @buffer: The ring buffer | |
2242 | * @cpu: The CPU buffer to test | |
2243 | */ | |
2244 | int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) | |
2245 | { | |
2246 | struct ring_buffer_per_cpu *cpu_buffer; | |
2247 | ||
9e01c1b7 | 2248 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
7a8e76a3 SR |
2249 | return 1; |
2250 | ||
2251 | cpu_buffer = buffer->buffers[cpu]; | |
2252 | return rb_per_cpu_empty(cpu_buffer); | |
2253 | } | |
c4f50183 | 2254 | EXPORT_SYMBOL_GPL(ring_buffer_empty_cpu); |
7a8e76a3 SR |
2255 | |
2256 | /** | |
2257 | * ring_buffer_swap_cpu - swap a CPU buffer between two ring buffers | |
2258 | * @buffer_a: One buffer to swap with | |
2259 | * @buffer_b: The other buffer to swap with | |
2260 | * | |
2261 | * This function is useful for tracers that want to take a "snapshot" | |
2262 | * of a CPU buffer and has another back up buffer lying around. | |
2263 | * it is expected that the tracer handles the cpu buffer not being | |
2264 | * used at the moment. | |
2265 | */ | |
2266 | int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, | |
2267 | struct ring_buffer *buffer_b, int cpu) | |
2268 | { | |
2269 | struct ring_buffer_per_cpu *cpu_buffer_a; | |
2270 | struct ring_buffer_per_cpu *cpu_buffer_b; | |
2271 | ||
9e01c1b7 RR |
2272 | if (!cpumask_test_cpu(cpu, buffer_a->cpumask) || |
2273 | !cpumask_test_cpu(cpu, buffer_b->cpumask)) | |
7a8e76a3 SR |
2274 | return -EINVAL; |
2275 | ||
2276 | /* At least make sure the two buffers are somewhat the same */ | |
6d102bc6 | 2277 | if (buffer_a->pages != buffer_b->pages) |
7a8e76a3 SR |
2278 | return -EINVAL; |
2279 | ||
2280 | cpu_buffer_a = buffer_a->buffers[cpu]; | |
2281 | cpu_buffer_b = buffer_b->buffers[cpu]; | |
2282 | ||
2283 | /* | |
2284 | * We can't do a synchronize_sched here because this | |
2285 | * function can be called in atomic context. | |
2286 | * Normally this will be called from the same CPU as cpu. | |
2287 | * If not it's up to the caller to protect this. | |
2288 | */ | |
2289 | atomic_inc(&cpu_buffer_a->record_disabled); | |
2290 | atomic_inc(&cpu_buffer_b->record_disabled); | |
2291 | ||
2292 | buffer_a->buffers[cpu] = cpu_buffer_b; | |
2293 | buffer_b->buffers[cpu] = cpu_buffer_a; | |
2294 | ||
2295 | cpu_buffer_b->buffer = buffer_a; | |
2296 | cpu_buffer_a->buffer = buffer_b; | |
2297 | ||
2298 | atomic_dec(&cpu_buffer_a->record_disabled); | |
2299 | atomic_dec(&cpu_buffer_b->record_disabled); | |
2300 | ||
2301 | return 0; | |
2302 | } | |
c4f50183 | 2303 | EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu); |
7a8e76a3 | 2304 | |
8789a9e7 | 2305 | static void rb_remove_entries(struct ring_buffer_per_cpu *cpu_buffer, |
044fa782 | 2306 | struct buffer_data_page *bpage) |
8789a9e7 SR |
2307 | { |
2308 | struct ring_buffer_event *event; | |
2309 | unsigned long head; | |
2310 | ||
2311 | __raw_spin_lock(&cpu_buffer->lock); | |
044fa782 | 2312 | for (head = 0; head < local_read(&bpage->commit); |
8789a9e7 SR |
2313 | head += rb_event_length(event)) { |
2314 | ||
044fa782 | 2315 | event = __rb_data_page_index(bpage, head); |
8789a9e7 SR |
2316 | if (RB_WARN_ON(cpu_buffer, rb_null_event(event))) |
2317 | return; | |
2318 | /* Only count data entries */ | |
2319 | if (event->type != RINGBUF_TYPE_DATA) | |
2320 | continue; | |
2321 | cpu_buffer->entries--; | |
2322 | } | |
2323 | __raw_spin_unlock(&cpu_buffer->lock); | |
2324 | } | |
2325 | ||
2326 | /** | |
2327 | * ring_buffer_alloc_read_page - allocate a page to read from buffer | |
2328 | * @buffer: the buffer to allocate for. | |
2329 | * | |
2330 | * This function is used in conjunction with ring_buffer_read_page. | |
2331 | * When reading a full page from the ring buffer, these functions | |
2332 | * can be used to speed up the process. The calling function should | |
2333 | * allocate a few pages first with this function. Then when it | |
2334 | * needs to get pages from the ring buffer, it passes the result | |
2335 | * of this function into ring_buffer_read_page, which will swap | |
2336 | * the page that was allocated, with the read page of the buffer. | |
2337 | * | |
2338 | * Returns: | |
2339 | * The page allocated, or NULL on error. | |
2340 | */ | |
2341 | void *ring_buffer_alloc_read_page(struct ring_buffer *buffer) | |
2342 | { | |
2343 | unsigned long addr; | |
044fa782 | 2344 | struct buffer_data_page *bpage; |
8789a9e7 SR |
2345 | |
2346 | addr = __get_free_page(GFP_KERNEL); | |
2347 | if (!addr) | |
2348 | return NULL; | |
2349 | ||
044fa782 | 2350 | bpage = (void *)addr; |
8789a9e7 | 2351 | |
044fa782 | 2352 | return bpage; |
8789a9e7 SR |
2353 | } |
2354 | ||
2355 | /** | |
2356 | * ring_buffer_free_read_page - free an allocated read page | |
2357 | * @buffer: the buffer the page was allocate for | |
2358 | * @data: the page to free | |
2359 | * | |
2360 | * Free a page allocated from ring_buffer_alloc_read_page. | |
2361 | */ | |
2362 | void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data) | |
2363 | { | |
2364 | free_page((unsigned long)data); | |
2365 | } | |
2366 | ||
2367 | /** | |
2368 | * ring_buffer_read_page - extract a page from the ring buffer | |
2369 | * @buffer: buffer to extract from | |
2370 | * @data_page: the page to use allocated from ring_buffer_alloc_read_page | |
2371 | * @cpu: the cpu of the buffer to extract | |
2372 | * @full: should the extraction only happen when the page is full. | |
2373 | * | |
2374 | * This function will pull out a page from the ring buffer and consume it. | |
2375 | * @data_page must be the address of the variable that was returned | |
2376 | * from ring_buffer_alloc_read_page. This is because the page might be used | |
2377 | * to swap with a page in the ring buffer. | |
2378 | * | |
2379 | * for example: | |
2380 | * rpage = ring_buffer_alloc_page(buffer); | |
2381 | * if (!rpage) | |
2382 | * return error; | |
2383 | * ret = ring_buffer_read_page(buffer, &rpage, cpu, 0); | |
2384 | * if (ret) | |
2385 | * process_page(rpage); | |
2386 | * | |
2387 | * When @full is set, the function will not return true unless | |
2388 | * the writer is off the reader page. | |
2389 | * | |
2390 | * Note: it is up to the calling functions to handle sleeps and wakeups. | |
2391 | * The ring buffer can be used anywhere in the kernel and can not | |
2392 | * blindly call wake_up. The layer that uses the ring buffer must be | |
2393 | * responsible for that. | |
2394 | * | |
2395 | * Returns: | |
2396 | * 1 if data has been transferred | |
2397 | * 0 if no data has been transferred. | |
2398 | */ | |
2399 | int ring_buffer_read_page(struct ring_buffer *buffer, | |
2400 | void **data_page, int cpu, int full) | |
2401 | { | |
2402 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
2403 | struct ring_buffer_event *event; | |
044fa782 | 2404 | struct buffer_data_page *bpage; |
8789a9e7 SR |
2405 | unsigned long flags; |
2406 | int ret = 0; | |
2407 | ||
2408 | if (!data_page) | |
2409 | return 0; | |
2410 | ||
044fa782 SR |
2411 | bpage = *data_page; |
2412 | if (!bpage) | |
8789a9e7 SR |
2413 | return 0; |
2414 | ||
2415 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
2416 | ||
2417 | /* | |
2418 | * rb_buffer_peek will get the next ring buffer if | |
2419 | * the current reader page is empty. | |
2420 | */ | |
2421 | event = rb_buffer_peek(buffer, cpu, NULL); | |
2422 | if (!event) | |
2423 | goto out; | |
2424 | ||
2425 | /* check for data */ | |
2426 | if (!local_read(&cpu_buffer->reader_page->page->commit)) | |
2427 | goto out; | |
2428 | /* | |
2429 | * If the writer is already off of the read page, then simply | |
2430 | * switch the read page with the given page. Otherwise | |
2431 | * we need to copy the data from the reader to the writer. | |
2432 | */ | |
2433 | if (cpu_buffer->reader_page == cpu_buffer->commit_page) { | |
2434 | unsigned int read = cpu_buffer->reader_page->read; | |
2435 | ||
2436 | if (full) | |
2437 | goto out; | |
2438 | /* The writer is still on the reader page, we must copy */ | |
044fa782 SR |
2439 | bpage = cpu_buffer->reader_page->page; |
2440 | memcpy(bpage->data, | |
8789a9e7 | 2441 | cpu_buffer->reader_page->page->data + read, |
044fa782 | 2442 | local_read(&bpage->commit) - read); |
8789a9e7 SR |
2443 | |
2444 | /* consume what was read */ | |
2445 | cpu_buffer->reader_page += read; | |
2446 | ||
2447 | } else { | |
2448 | /* swap the pages */ | |
044fa782 SR |
2449 | rb_init_page(bpage); |
2450 | bpage = cpu_buffer->reader_page->page; | |
8789a9e7 SR |
2451 | cpu_buffer->reader_page->page = *data_page; |
2452 | cpu_buffer->reader_page->read = 0; | |
044fa782 | 2453 | *data_page = bpage; |
8789a9e7 SR |
2454 | } |
2455 | ret = 1; | |
2456 | ||
2457 | /* update the entry counter */ | |
044fa782 | 2458 | rb_remove_entries(cpu_buffer, bpage); |
8789a9e7 SR |
2459 | out: |
2460 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
2461 | ||
2462 | return ret; | |
2463 | } | |
2464 | ||
a3583244 SR |
2465 | static ssize_t |
2466 | rb_simple_read(struct file *filp, char __user *ubuf, | |
2467 | size_t cnt, loff_t *ppos) | |
2468 | { | |
033601a3 | 2469 | long *p = filp->private_data; |
a3583244 SR |
2470 | char buf[64]; |
2471 | int r; | |
2472 | ||
033601a3 SR |
2473 | if (test_bit(RB_BUFFERS_DISABLED_BIT, p)) |
2474 | r = sprintf(buf, "permanently disabled\n"); | |
2475 | else | |
2476 | r = sprintf(buf, "%d\n", test_bit(RB_BUFFERS_ON_BIT, p)); | |
a3583244 SR |
2477 | |
2478 | return simple_read_from_buffer(ubuf, cnt, ppos, buf, r); | |
2479 | } | |
2480 | ||
2481 | static ssize_t | |
2482 | rb_simple_write(struct file *filp, const char __user *ubuf, | |
2483 | size_t cnt, loff_t *ppos) | |
2484 | { | |
033601a3 | 2485 | long *p = filp->private_data; |
a3583244 SR |
2486 | char buf[64]; |
2487 | long val; | |
2488 | int ret; | |
2489 | ||
2490 | if (cnt >= sizeof(buf)) | |
2491 | return -EINVAL; | |
2492 | ||
2493 | if (copy_from_user(&buf, ubuf, cnt)) | |
2494 | return -EFAULT; | |
2495 | ||
2496 | buf[cnt] = 0; | |
2497 | ||
2498 | ret = strict_strtoul(buf, 10, &val); | |
2499 | if (ret < 0) | |
2500 | return ret; | |
2501 | ||
033601a3 SR |
2502 | if (val) |
2503 | set_bit(RB_BUFFERS_ON_BIT, p); | |
2504 | else | |
2505 | clear_bit(RB_BUFFERS_ON_BIT, p); | |
a3583244 SR |
2506 | |
2507 | (*ppos)++; | |
2508 | ||
2509 | return cnt; | |
2510 | } | |
2511 | ||
2512 | static struct file_operations rb_simple_fops = { | |
2513 | .open = tracing_open_generic, | |
2514 | .read = rb_simple_read, | |
2515 | .write = rb_simple_write, | |
2516 | }; | |
2517 | ||
2518 | ||
2519 | static __init int rb_init_debugfs(void) | |
2520 | { | |
2521 | struct dentry *d_tracer; | |
2522 | struct dentry *entry; | |
2523 | ||
2524 | d_tracer = tracing_init_dentry(); | |
2525 | ||
2526 | entry = debugfs_create_file("tracing_on", 0644, d_tracer, | |
033601a3 | 2527 | &ring_buffer_flags, &rb_simple_fops); |
a3583244 SR |
2528 | if (!entry) |
2529 | pr_warning("Could not create debugfs 'tracing_on' entry\n"); | |
2530 | ||
2531 | return 0; | |
2532 | } | |
2533 | ||
2534 | fs_initcall(rb_init_debugfs); |