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> | |
14131f2f | 7 | #include <linux/trace_clock.h> |
78d904b4 | 8 | #include <linux/ftrace_irq.h> |
7a8e76a3 SR |
9 | #include <linux/spinlock.h> |
10 | #include <linux/debugfs.h> | |
11 | #include <linux/uaccess.h> | |
a81bd80a | 12 | #include <linux/hardirq.h> |
7a8e76a3 SR |
13 | #include <linux/module.h> |
14 | #include <linux/percpu.h> | |
15 | #include <linux/mutex.h> | |
7a8e76a3 SR |
16 | #include <linux/init.h> |
17 | #include <linux/hash.h> | |
18 | #include <linux/list.h> | |
554f786e | 19 | #include <linux/cpu.h> |
7a8e76a3 SR |
20 | #include <linux/fs.h> |
21 | ||
182e9f5f SR |
22 | #include "trace.h" |
23 | ||
5cc98548 SR |
24 | /* |
25 | * The ring buffer is made up of a list of pages. A separate list of pages is | |
26 | * allocated for each CPU. A writer may only write to a buffer that is | |
27 | * associated with the CPU it is currently executing on. A reader may read | |
28 | * from any per cpu buffer. | |
29 | * | |
30 | * The reader is special. For each per cpu buffer, the reader has its own | |
31 | * reader page. When a reader has read the entire reader page, this reader | |
32 | * page is swapped with another page in the ring buffer. | |
33 | * | |
34 | * Now, as long as the writer is off the reader page, the reader can do what | |
35 | * ever it wants with that page. The writer will never write to that page | |
36 | * again (as long as it is out of the ring buffer). | |
37 | * | |
38 | * Here's some silly ASCII art. | |
39 | * | |
40 | * +------+ | |
41 | * |reader| RING BUFFER | |
42 | * |page | | |
43 | * +------+ +---+ +---+ +---+ | |
44 | * | |-->| |-->| | | |
45 | * +---+ +---+ +---+ | |
46 | * ^ | | |
47 | * | | | |
48 | * +---------------+ | |
49 | * | |
50 | * | |
51 | * +------+ | |
52 | * |reader| RING BUFFER | |
53 | * |page |------------------v | |
54 | * +------+ +---+ +---+ +---+ | |
55 | * | |-->| |-->| | | |
56 | * +---+ +---+ +---+ | |
57 | * ^ | | |
58 | * | | | |
59 | * +---------------+ | |
60 | * | |
61 | * | |
62 | * +------+ | |
63 | * |reader| RING BUFFER | |
64 | * |page |------------------v | |
65 | * +------+ +---+ +---+ +---+ | |
66 | * ^ | |-->| |-->| | | |
67 | * | +---+ +---+ +---+ | |
68 | * | | | |
69 | * | | | |
70 | * +------------------------------+ | |
71 | * | |
72 | * | |
73 | * +------+ | |
74 | * |buffer| RING BUFFER | |
75 | * |page |------------------v | |
76 | * +------+ +---+ +---+ +---+ | |
77 | * ^ | | | |-->| | | |
78 | * | New +---+ +---+ +---+ | |
79 | * | Reader------^ | | |
80 | * | page | | |
81 | * +------------------------------+ | |
82 | * | |
83 | * | |
84 | * After we make this swap, the reader can hand this page off to the splice | |
85 | * code and be done with it. It can even allocate a new page if it needs to | |
86 | * and swap that into the ring buffer. | |
87 | * | |
88 | * We will be using cmpxchg soon to make all this lockless. | |
89 | * | |
90 | */ | |
91 | ||
033601a3 SR |
92 | /* |
93 | * A fast way to enable or disable all ring buffers is to | |
94 | * call tracing_on or tracing_off. Turning off the ring buffers | |
95 | * prevents all ring buffers from being recorded to. | |
96 | * Turning this switch on, makes it OK to write to the | |
97 | * ring buffer, if the ring buffer is enabled itself. | |
98 | * | |
99 | * There's three layers that must be on in order to write | |
100 | * to the ring buffer. | |
101 | * | |
102 | * 1) This global flag must be set. | |
103 | * 2) The ring buffer must be enabled for recording. | |
104 | * 3) The per cpu buffer must be enabled for recording. | |
105 | * | |
106 | * In case of an anomaly, this global flag has a bit set that | |
107 | * will permantly disable all ring buffers. | |
108 | */ | |
109 | ||
110 | /* | |
111 | * Global flag to disable all recording to ring buffers | |
112 | * This has two bits: ON, DISABLED | |
113 | * | |
114 | * ON DISABLED | |
115 | * ---- ---------- | |
116 | * 0 0 : ring buffers are off | |
117 | * 1 0 : ring buffers are on | |
118 | * X 1 : ring buffers are permanently disabled | |
119 | */ | |
120 | ||
121 | enum { | |
122 | RB_BUFFERS_ON_BIT = 0, | |
123 | RB_BUFFERS_DISABLED_BIT = 1, | |
124 | }; | |
125 | ||
126 | enum { | |
127 | RB_BUFFERS_ON = 1 << RB_BUFFERS_ON_BIT, | |
128 | RB_BUFFERS_DISABLED = 1 << RB_BUFFERS_DISABLED_BIT, | |
129 | }; | |
130 | ||
5e39841c | 131 | static unsigned long ring_buffer_flags __read_mostly = RB_BUFFERS_ON; |
a3583244 | 132 | |
474d32b6 SR |
133 | #define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data) |
134 | ||
a3583244 SR |
135 | /** |
136 | * tracing_on - enable all tracing buffers | |
137 | * | |
138 | * This function enables all tracing buffers that may have been | |
139 | * disabled with tracing_off. | |
140 | */ | |
141 | void tracing_on(void) | |
142 | { | |
033601a3 | 143 | set_bit(RB_BUFFERS_ON_BIT, &ring_buffer_flags); |
a3583244 | 144 | } |
c4f50183 | 145 | EXPORT_SYMBOL_GPL(tracing_on); |
a3583244 SR |
146 | |
147 | /** | |
148 | * tracing_off - turn off all tracing buffers | |
149 | * | |
150 | * This function stops all tracing buffers from recording data. | |
151 | * It does not disable any overhead the tracers themselves may | |
152 | * be causing. This function simply causes all recording to | |
153 | * the ring buffers to fail. | |
154 | */ | |
155 | void tracing_off(void) | |
156 | { | |
033601a3 SR |
157 | clear_bit(RB_BUFFERS_ON_BIT, &ring_buffer_flags); |
158 | } | |
c4f50183 | 159 | EXPORT_SYMBOL_GPL(tracing_off); |
033601a3 SR |
160 | |
161 | /** | |
162 | * tracing_off_permanent - permanently disable ring buffers | |
163 | * | |
164 | * This function, once called, will disable all ring buffers | |
c3706f00 | 165 | * permanently. |
033601a3 SR |
166 | */ |
167 | void tracing_off_permanent(void) | |
168 | { | |
169 | set_bit(RB_BUFFERS_DISABLED_BIT, &ring_buffer_flags); | |
a3583244 SR |
170 | } |
171 | ||
988ae9d6 SR |
172 | /** |
173 | * tracing_is_on - show state of ring buffers enabled | |
174 | */ | |
175 | int tracing_is_on(void) | |
176 | { | |
177 | return ring_buffer_flags == RB_BUFFERS_ON; | |
178 | } | |
179 | EXPORT_SYMBOL_GPL(tracing_is_on); | |
180 | ||
d06bbd66 IM |
181 | #include "trace.h" |
182 | ||
e3d6bf0a | 183 | #define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array)) |
67d34724 | 184 | #define RB_ALIGNMENT 4U |
7a8e76a3 SR |
185 | #define RB_MAX_SMALL_DATA 28 |
186 | ||
187 | enum { | |
188 | RB_LEN_TIME_EXTEND = 8, | |
189 | RB_LEN_TIME_STAMP = 16, | |
190 | }; | |
191 | ||
192 | /* inline for ring buffer fast paths */ | |
34a148bf | 193 | static unsigned |
7a8e76a3 SR |
194 | rb_event_length(struct ring_buffer_event *event) |
195 | { | |
196 | unsigned length; | |
197 | ||
198 | switch (event->type) { | |
199 | case RINGBUF_TYPE_PADDING: | |
200 | /* undefined */ | |
201 | return -1; | |
202 | ||
203 | case RINGBUF_TYPE_TIME_EXTEND: | |
204 | return RB_LEN_TIME_EXTEND; | |
205 | ||
206 | case RINGBUF_TYPE_TIME_STAMP: | |
207 | return RB_LEN_TIME_STAMP; | |
208 | ||
209 | case RINGBUF_TYPE_DATA: | |
210 | if (event->len) | |
67d34724 | 211 | length = event->len * RB_ALIGNMENT; |
7a8e76a3 SR |
212 | else |
213 | length = event->array[0]; | |
214 | return length + RB_EVNT_HDR_SIZE; | |
215 | default: | |
216 | BUG(); | |
217 | } | |
218 | /* not hit */ | |
219 | return 0; | |
220 | } | |
221 | ||
222 | /** | |
223 | * ring_buffer_event_length - return the length of the event | |
224 | * @event: the event to get the length of | |
225 | */ | |
226 | unsigned ring_buffer_event_length(struct ring_buffer_event *event) | |
227 | { | |
465634ad RR |
228 | unsigned length = rb_event_length(event); |
229 | if (event->type != RINGBUF_TYPE_DATA) | |
230 | return length; | |
231 | length -= RB_EVNT_HDR_SIZE; | |
232 | if (length > RB_MAX_SMALL_DATA + sizeof(event->array[0])) | |
233 | length -= sizeof(event->array[0]); | |
234 | return length; | |
7a8e76a3 | 235 | } |
c4f50183 | 236 | EXPORT_SYMBOL_GPL(ring_buffer_event_length); |
7a8e76a3 SR |
237 | |
238 | /* inline for ring buffer fast paths */ | |
34a148bf | 239 | static void * |
7a8e76a3 SR |
240 | rb_event_data(struct ring_buffer_event *event) |
241 | { | |
242 | BUG_ON(event->type != RINGBUF_TYPE_DATA); | |
243 | /* If length is in len field, then array[0] has the data */ | |
244 | if (event->len) | |
245 | return (void *)&event->array[0]; | |
246 | /* Otherwise length is in array[0] and array[1] has the data */ | |
247 | return (void *)&event->array[1]; | |
248 | } | |
249 | ||
250 | /** | |
251 | * ring_buffer_event_data - return the data of the event | |
252 | * @event: the event to get the data from | |
253 | */ | |
254 | void *ring_buffer_event_data(struct ring_buffer_event *event) | |
255 | { | |
256 | return rb_event_data(event); | |
257 | } | |
c4f50183 | 258 | EXPORT_SYMBOL_GPL(ring_buffer_event_data); |
7a8e76a3 SR |
259 | |
260 | #define for_each_buffer_cpu(buffer, cpu) \ | |
9e01c1b7 | 261 | for_each_cpu(cpu, buffer->cpumask) |
7a8e76a3 SR |
262 | |
263 | #define TS_SHIFT 27 | |
264 | #define TS_MASK ((1ULL << TS_SHIFT) - 1) | |
265 | #define TS_DELTA_TEST (~TS_MASK) | |
266 | ||
abc9b56d | 267 | struct buffer_data_page { |
e4c2ce82 | 268 | u64 time_stamp; /* page time stamp */ |
c3706f00 | 269 | local_t commit; /* write committed index */ |
abc9b56d SR |
270 | unsigned char data[]; /* data of buffer page */ |
271 | }; | |
272 | ||
273 | struct buffer_page { | |
274 | local_t write; /* index for next write */ | |
6f807acd | 275 | unsigned read; /* index for next read */ |
e4c2ce82 | 276 | struct list_head list; /* list of free pages */ |
abc9b56d | 277 | struct buffer_data_page *page; /* Actual data page */ |
7a8e76a3 SR |
278 | }; |
279 | ||
044fa782 | 280 | static void rb_init_page(struct buffer_data_page *bpage) |
abc9b56d | 281 | { |
044fa782 | 282 | local_set(&bpage->commit, 0); |
abc9b56d SR |
283 | } |
284 | ||
474d32b6 SR |
285 | /** |
286 | * ring_buffer_page_len - the size of data on the page. | |
287 | * @page: The page to read | |
288 | * | |
289 | * Returns the amount of data on the page, including buffer page header. | |
290 | */ | |
ef7a4a16 SR |
291 | size_t ring_buffer_page_len(void *page) |
292 | { | |
474d32b6 SR |
293 | return local_read(&((struct buffer_data_page *)page)->commit) |
294 | + BUF_PAGE_HDR_SIZE; | |
ef7a4a16 SR |
295 | } |
296 | ||
ed56829c SR |
297 | /* |
298 | * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing | |
299 | * this issue out. | |
300 | */ | |
34a148bf | 301 | static void free_buffer_page(struct buffer_page *bpage) |
ed56829c | 302 | { |
34a148bf | 303 | free_page((unsigned long)bpage->page); |
e4c2ce82 | 304 | kfree(bpage); |
ed56829c SR |
305 | } |
306 | ||
7a8e76a3 SR |
307 | /* |
308 | * We need to fit the time_stamp delta into 27 bits. | |
309 | */ | |
310 | static inline int test_time_stamp(u64 delta) | |
311 | { | |
312 | if (delta & TS_DELTA_TEST) | |
313 | return 1; | |
314 | return 0; | |
315 | } | |
316 | ||
474d32b6 | 317 | #define BUF_PAGE_SIZE (PAGE_SIZE - BUF_PAGE_HDR_SIZE) |
7a8e76a3 SR |
318 | |
319 | /* | |
320 | * head_page == tail_page && head == tail then buffer is empty. | |
321 | */ | |
322 | struct ring_buffer_per_cpu { | |
323 | int cpu; | |
324 | struct ring_buffer *buffer; | |
f83c9d0f | 325 | spinlock_t reader_lock; /* serialize readers */ |
3e03fb7f | 326 | raw_spinlock_t lock; |
7a8e76a3 SR |
327 | struct lock_class_key lock_key; |
328 | struct list_head pages; | |
6f807acd SR |
329 | struct buffer_page *head_page; /* read from head */ |
330 | struct buffer_page *tail_page; /* write to tail */ | |
c3706f00 | 331 | struct buffer_page *commit_page; /* committed pages */ |
d769041f | 332 | struct buffer_page *reader_page; |
7a8e76a3 SR |
333 | unsigned long overrun; |
334 | unsigned long entries; | |
335 | u64 write_stamp; | |
336 | u64 read_stamp; | |
337 | atomic_t record_disabled; | |
338 | }; | |
339 | ||
340 | struct ring_buffer { | |
7a8e76a3 SR |
341 | unsigned pages; |
342 | unsigned flags; | |
343 | int cpus; | |
7a8e76a3 | 344 | atomic_t record_disabled; |
00f62f61 | 345 | cpumask_var_t cpumask; |
7a8e76a3 SR |
346 | |
347 | struct mutex mutex; | |
348 | ||
349 | struct ring_buffer_per_cpu **buffers; | |
554f786e | 350 | |
59222efe | 351 | #ifdef CONFIG_HOTPLUG_CPU |
554f786e SR |
352 | struct notifier_block cpu_notify; |
353 | #endif | |
37886f6a | 354 | u64 (*clock)(void); |
7a8e76a3 SR |
355 | }; |
356 | ||
357 | struct ring_buffer_iter { | |
358 | struct ring_buffer_per_cpu *cpu_buffer; | |
359 | unsigned long head; | |
360 | struct buffer_page *head_page; | |
361 | u64 read_stamp; | |
362 | }; | |
363 | ||
f536aafc | 364 | /* buffer may be either ring_buffer or ring_buffer_per_cpu */ |
bf41a158 | 365 | #define RB_WARN_ON(buffer, cond) \ |
3e89c7bb SR |
366 | ({ \ |
367 | int _____ret = unlikely(cond); \ | |
368 | if (_____ret) { \ | |
bf41a158 SR |
369 | atomic_inc(&buffer->record_disabled); \ |
370 | WARN_ON(1); \ | |
371 | } \ | |
3e89c7bb SR |
372 | _____ret; \ |
373 | }) | |
f536aafc | 374 | |
37886f6a SR |
375 | /* Up this if you want to test the TIME_EXTENTS and normalization */ |
376 | #define DEBUG_SHIFT 0 | |
377 | ||
378 | u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu) | |
379 | { | |
380 | u64 time; | |
381 | ||
382 | preempt_disable_notrace(); | |
383 | /* shift to debug/test normalization and TIME_EXTENTS */ | |
384 | time = buffer->clock() << DEBUG_SHIFT; | |
385 | preempt_enable_no_resched_notrace(); | |
386 | ||
387 | return time; | |
388 | } | |
389 | EXPORT_SYMBOL_GPL(ring_buffer_time_stamp); | |
390 | ||
391 | void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer, | |
392 | int cpu, u64 *ts) | |
393 | { | |
394 | /* Just stupid testing the normalize function and deltas */ | |
395 | *ts >>= DEBUG_SHIFT; | |
396 | } | |
397 | EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp); | |
398 | ||
7a8e76a3 SR |
399 | /** |
400 | * check_pages - integrity check of buffer pages | |
401 | * @cpu_buffer: CPU buffer with pages to test | |
402 | * | |
c3706f00 | 403 | * As a safety measure we check to make sure the data pages have not |
7a8e76a3 SR |
404 | * been corrupted. |
405 | */ | |
406 | static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) | |
407 | { | |
408 | struct list_head *head = &cpu_buffer->pages; | |
044fa782 | 409 | struct buffer_page *bpage, *tmp; |
7a8e76a3 | 410 | |
3e89c7bb SR |
411 | if (RB_WARN_ON(cpu_buffer, head->next->prev != head)) |
412 | return -1; | |
413 | if (RB_WARN_ON(cpu_buffer, head->prev->next != head)) | |
414 | return -1; | |
7a8e76a3 | 415 | |
044fa782 | 416 | list_for_each_entry_safe(bpage, tmp, head, list) { |
3e89c7bb | 417 | if (RB_WARN_ON(cpu_buffer, |
044fa782 | 418 | bpage->list.next->prev != &bpage->list)) |
3e89c7bb SR |
419 | return -1; |
420 | if (RB_WARN_ON(cpu_buffer, | |
044fa782 | 421 | bpage->list.prev->next != &bpage->list)) |
3e89c7bb | 422 | return -1; |
7a8e76a3 SR |
423 | } |
424 | ||
425 | return 0; | |
426 | } | |
427 | ||
7a8e76a3 SR |
428 | static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, |
429 | unsigned nr_pages) | |
430 | { | |
431 | struct list_head *head = &cpu_buffer->pages; | |
044fa782 | 432 | struct buffer_page *bpage, *tmp; |
7a8e76a3 SR |
433 | unsigned long addr; |
434 | LIST_HEAD(pages); | |
435 | unsigned i; | |
436 | ||
437 | for (i = 0; i < nr_pages; i++) { | |
044fa782 | 438 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
aa1e0e3b | 439 | GFP_KERNEL, cpu_to_node(cpu_buffer->cpu)); |
044fa782 | 440 | if (!bpage) |
e4c2ce82 | 441 | goto free_pages; |
044fa782 | 442 | list_add(&bpage->list, &pages); |
e4c2ce82 | 443 | |
7a8e76a3 SR |
444 | addr = __get_free_page(GFP_KERNEL); |
445 | if (!addr) | |
446 | goto free_pages; | |
044fa782 SR |
447 | bpage->page = (void *)addr; |
448 | rb_init_page(bpage->page); | |
7a8e76a3 SR |
449 | } |
450 | ||
451 | list_splice(&pages, head); | |
452 | ||
453 | rb_check_pages(cpu_buffer); | |
454 | ||
455 | return 0; | |
456 | ||
457 | free_pages: | |
044fa782 SR |
458 | list_for_each_entry_safe(bpage, tmp, &pages, list) { |
459 | list_del_init(&bpage->list); | |
460 | free_buffer_page(bpage); | |
7a8e76a3 SR |
461 | } |
462 | return -ENOMEM; | |
463 | } | |
464 | ||
465 | static struct ring_buffer_per_cpu * | |
466 | rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu) | |
467 | { | |
468 | struct ring_buffer_per_cpu *cpu_buffer; | |
044fa782 | 469 | struct buffer_page *bpage; |
d769041f | 470 | unsigned long addr; |
7a8e76a3 SR |
471 | int ret; |
472 | ||
473 | cpu_buffer = kzalloc_node(ALIGN(sizeof(*cpu_buffer), cache_line_size()), | |
474 | GFP_KERNEL, cpu_to_node(cpu)); | |
475 | if (!cpu_buffer) | |
476 | return NULL; | |
477 | ||
478 | cpu_buffer->cpu = cpu; | |
479 | cpu_buffer->buffer = buffer; | |
f83c9d0f | 480 | spin_lock_init(&cpu_buffer->reader_lock); |
3e03fb7f | 481 | cpu_buffer->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED; |
7a8e76a3 SR |
482 | INIT_LIST_HEAD(&cpu_buffer->pages); |
483 | ||
044fa782 | 484 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
e4c2ce82 | 485 | GFP_KERNEL, cpu_to_node(cpu)); |
044fa782 | 486 | if (!bpage) |
e4c2ce82 SR |
487 | goto fail_free_buffer; |
488 | ||
044fa782 | 489 | cpu_buffer->reader_page = bpage; |
d769041f SR |
490 | addr = __get_free_page(GFP_KERNEL); |
491 | if (!addr) | |
e4c2ce82 | 492 | goto fail_free_reader; |
044fa782 SR |
493 | bpage->page = (void *)addr; |
494 | rb_init_page(bpage->page); | |
e4c2ce82 | 495 | |
d769041f | 496 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); |
d769041f | 497 | |
7a8e76a3 SR |
498 | ret = rb_allocate_pages(cpu_buffer, buffer->pages); |
499 | if (ret < 0) | |
d769041f | 500 | goto fail_free_reader; |
7a8e76a3 SR |
501 | |
502 | cpu_buffer->head_page | |
503 | = list_entry(cpu_buffer->pages.next, struct buffer_page, list); | |
bf41a158 | 504 | cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; |
7a8e76a3 SR |
505 | |
506 | return cpu_buffer; | |
507 | ||
d769041f SR |
508 | fail_free_reader: |
509 | free_buffer_page(cpu_buffer->reader_page); | |
510 | ||
7a8e76a3 SR |
511 | fail_free_buffer: |
512 | kfree(cpu_buffer); | |
513 | return NULL; | |
514 | } | |
515 | ||
516 | static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) | |
517 | { | |
518 | struct list_head *head = &cpu_buffer->pages; | |
044fa782 | 519 | struct buffer_page *bpage, *tmp; |
7a8e76a3 | 520 | |
d769041f SR |
521 | list_del_init(&cpu_buffer->reader_page->list); |
522 | free_buffer_page(cpu_buffer->reader_page); | |
523 | ||
044fa782 SR |
524 | list_for_each_entry_safe(bpage, tmp, head, list) { |
525 | list_del_init(&bpage->list); | |
526 | free_buffer_page(bpage); | |
7a8e76a3 SR |
527 | } |
528 | kfree(cpu_buffer); | |
529 | } | |
530 | ||
a7b13743 SR |
531 | /* |
532 | * Causes compile errors if the struct buffer_page gets bigger | |
533 | * than the struct page. | |
534 | */ | |
535 | extern int ring_buffer_page_too_big(void); | |
536 | ||
59222efe | 537 | #ifdef CONFIG_HOTPLUG_CPU |
554f786e SR |
538 | static int __cpuinit rb_cpu_notify(struct notifier_block *self, |
539 | unsigned long action, void *hcpu); | |
540 | #endif | |
541 | ||
7a8e76a3 SR |
542 | /** |
543 | * ring_buffer_alloc - allocate a new ring_buffer | |
68814b58 | 544 | * @size: the size in bytes per cpu that is needed. |
7a8e76a3 SR |
545 | * @flags: attributes to set for the ring buffer. |
546 | * | |
547 | * Currently the only flag that is available is the RB_FL_OVERWRITE | |
548 | * flag. This flag means that the buffer will overwrite old data | |
549 | * when the buffer wraps. If this flag is not set, the buffer will | |
550 | * drop data when the tail hits the head. | |
551 | */ | |
552 | struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags) | |
553 | { | |
554 | struct ring_buffer *buffer; | |
555 | int bsize; | |
556 | int cpu; | |
557 | ||
a7b13743 SR |
558 | /* Paranoid! Optimizes out when all is well */ |
559 | if (sizeof(struct buffer_page) > sizeof(struct page)) | |
560 | ring_buffer_page_too_big(); | |
561 | ||
562 | ||
7a8e76a3 SR |
563 | /* keep it in its own cache line */ |
564 | buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()), | |
565 | GFP_KERNEL); | |
566 | if (!buffer) | |
567 | return NULL; | |
568 | ||
9e01c1b7 RR |
569 | if (!alloc_cpumask_var(&buffer->cpumask, GFP_KERNEL)) |
570 | goto fail_free_buffer; | |
571 | ||
7a8e76a3 SR |
572 | buffer->pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
573 | buffer->flags = flags; | |
37886f6a | 574 | buffer->clock = trace_clock_local; |
7a8e76a3 SR |
575 | |
576 | /* need at least two pages */ | |
577 | if (buffer->pages == 1) | |
578 | buffer->pages++; | |
579 | ||
554f786e SR |
580 | get_online_cpus(); |
581 | cpumask_copy(buffer->cpumask, cpu_online_mask); | |
7a8e76a3 SR |
582 | buffer->cpus = nr_cpu_ids; |
583 | ||
584 | bsize = sizeof(void *) * nr_cpu_ids; | |
585 | buffer->buffers = kzalloc(ALIGN(bsize, cache_line_size()), | |
586 | GFP_KERNEL); | |
587 | if (!buffer->buffers) | |
9e01c1b7 | 588 | goto fail_free_cpumask; |
7a8e76a3 SR |
589 | |
590 | for_each_buffer_cpu(buffer, cpu) { | |
591 | buffer->buffers[cpu] = | |
592 | rb_allocate_cpu_buffer(buffer, cpu); | |
593 | if (!buffer->buffers[cpu]) | |
594 | goto fail_free_buffers; | |
595 | } | |
596 | ||
59222efe | 597 | #ifdef CONFIG_HOTPLUG_CPU |
554f786e SR |
598 | buffer->cpu_notify.notifier_call = rb_cpu_notify; |
599 | buffer->cpu_notify.priority = 0; | |
600 | register_cpu_notifier(&buffer->cpu_notify); | |
601 | #endif | |
602 | ||
603 | put_online_cpus(); | |
7a8e76a3 SR |
604 | mutex_init(&buffer->mutex); |
605 | ||
606 | return buffer; | |
607 | ||
608 | fail_free_buffers: | |
609 | for_each_buffer_cpu(buffer, cpu) { | |
610 | if (buffer->buffers[cpu]) | |
611 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
612 | } | |
613 | kfree(buffer->buffers); | |
614 | ||
9e01c1b7 RR |
615 | fail_free_cpumask: |
616 | free_cpumask_var(buffer->cpumask); | |
554f786e | 617 | put_online_cpus(); |
9e01c1b7 | 618 | |
7a8e76a3 SR |
619 | fail_free_buffer: |
620 | kfree(buffer); | |
621 | return NULL; | |
622 | } | |
c4f50183 | 623 | EXPORT_SYMBOL_GPL(ring_buffer_alloc); |
7a8e76a3 SR |
624 | |
625 | /** | |
626 | * ring_buffer_free - free a ring buffer. | |
627 | * @buffer: the buffer to free. | |
628 | */ | |
629 | void | |
630 | ring_buffer_free(struct ring_buffer *buffer) | |
631 | { | |
632 | int cpu; | |
633 | ||
554f786e SR |
634 | get_online_cpus(); |
635 | ||
59222efe | 636 | #ifdef CONFIG_HOTPLUG_CPU |
554f786e SR |
637 | unregister_cpu_notifier(&buffer->cpu_notify); |
638 | #endif | |
639 | ||
7a8e76a3 SR |
640 | for_each_buffer_cpu(buffer, cpu) |
641 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
642 | ||
554f786e SR |
643 | put_online_cpus(); |
644 | ||
9e01c1b7 RR |
645 | free_cpumask_var(buffer->cpumask); |
646 | ||
7a8e76a3 SR |
647 | kfree(buffer); |
648 | } | |
c4f50183 | 649 | EXPORT_SYMBOL_GPL(ring_buffer_free); |
7a8e76a3 | 650 | |
37886f6a SR |
651 | void ring_buffer_set_clock(struct ring_buffer *buffer, |
652 | u64 (*clock)(void)) | |
653 | { | |
654 | buffer->clock = clock; | |
655 | } | |
656 | ||
7a8e76a3 SR |
657 | static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer); |
658 | ||
659 | static void | |
660 | rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages) | |
661 | { | |
044fa782 | 662 | struct buffer_page *bpage; |
7a8e76a3 SR |
663 | struct list_head *p; |
664 | unsigned i; | |
665 | ||
666 | atomic_inc(&cpu_buffer->record_disabled); | |
667 | synchronize_sched(); | |
668 | ||
669 | for (i = 0; i < nr_pages; i++) { | |
3e89c7bb SR |
670 | if (RB_WARN_ON(cpu_buffer, list_empty(&cpu_buffer->pages))) |
671 | return; | |
7a8e76a3 | 672 | p = cpu_buffer->pages.next; |
044fa782 SR |
673 | bpage = list_entry(p, struct buffer_page, list); |
674 | list_del_init(&bpage->list); | |
675 | free_buffer_page(bpage); | |
7a8e76a3 | 676 | } |
3e89c7bb SR |
677 | if (RB_WARN_ON(cpu_buffer, list_empty(&cpu_buffer->pages))) |
678 | return; | |
7a8e76a3 SR |
679 | |
680 | rb_reset_cpu(cpu_buffer); | |
681 | ||
682 | rb_check_pages(cpu_buffer); | |
683 | ||
684 | atomic_dec(&cpu_buffer->record_disabled); | |
685 | ||
686 | } | |
687 | ||
688 | static void | |
689 | rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer, | |
690 | struct list_head *pages, unsigned nr_pages) | |
691 | { | |
044fa782 | 692 | struct buffer_page *bpage; |
7a8e76a3 SR |
693 | struct list_head *p; |
694 | unsigned i; | |
695 | ||
696 | atomic_inc(&cpu_buffer->record_disabled); | |
697 | synchronize_sched(); | |
698 | ||
699 | for (i = 0; i < nr_pages; i++) { | |
3e89c7bb SR |
700 | if (RB_WARN_ON(cpu_buffer, list_empty(pages))) |
701 | return; | |
7a8e76a3 | 702 | p = pages->next; |
044fa782 SR |
703 | bpage = list_entry(p, struct buffer_page, list); |
704 | list_del_init(&bpage->list); | |
705 | list_add_tail(&bpage->list, &cpu_buffer->pages); | |
7a8e76a3 SR |
706 | } |
707 | rb_reset_cpu(cpu_buffer); | |
708 | ||
709 | rb_check_pages(cpu_buffer); | |
710 | ||
711 | atomic_dec(&cpu_buffer->record_disabled); | |
712 | } | |
713 | ||
714 | /** | |
715 | * ring_buffer_resize - resize the ring buffer | |
716 | * @buffer: the buffer to resize. | |
717 | * @size: the new size. | |
718 | * | |
719 | * The tracer is responsible for making sure that the buffer is | |
720 | * not being used while changing the size. | |
721 | * Note: We may be able to change the above requirement by using | |
722 | * RCU synchronizations. | |
723 | * | |
724 | * Minimum size is 2 * BUF_PAGE_SIZE. | |
725 | * | |
726 | * Returns -1 on failure. | |
727 | */ | |
728 | int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size) | |
729 | { | |
730 | struct ring_buffer_per_cpu *cpu_buffer; | |
731 | unsigned nr_pages, rm_pages, new_pages; | |
044fa782 | 732 | struct buffer_page *bpage, *tmp; |
7a8e76a3 SR |
733 | unsigned long buffer_size; |
734 | unsigned long addr; | |
735 | LIST_HEAD(pages); | |
736 | int i, cpu; | |
737 | ||
ee51a1de IM |
738 | /* |
739 | * Always succeed at resizing a non-existent buffer: | |
740 | */ | |
741 | if (!buffer) | |
742 | return size; | |
743 | ||
7a8e76a3 SR |
744 | size = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
745 | size *= BUF_PAGE_SIZE; | |
746 | buffer_size = buffer->pages * BUF_PAGE_SIZE; | |
747 | ||
748 | /* we need a minimum of two pages */ | |
749 | if (size < BUF_PAGE_SIZE * 2) | |
750 | size = BUF_PAGE_SIZE * 2; | |
751 | ||
752 | if (size == buffer_size) | |
753 | return size; | |
754 | ||
755 | mutex_lock(&buffer->mutex); | |
554f786e | 756 | get_online_cpus(); |
7a8e76a3 SR |
757 | |
758 | nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); | |
759 | ||
760 | if (size < buffer_size) { | |
761 | ||
762 | /* easy case, just free pages */ | |
554f786e SR |
763 | if (RB_WARN_ON(buffer, nr_pages >= buffer->pages)) |
764 | goto out_fail; | |
7a8e76a3 SR |
765 | |
766 | rm_pages = buffer->pages - nr_pages; | |
767 | ||
768 | for_each_buffer_cpu(buffer, cpu) { | |
769 | cpu_buffer = buffer->buffers[cpu]; | |
770 | rb_remove_pages(cpu_buffer, rm_pages); | |
771 | } | |
772 | goto out; | |
773 | } | |
774 | ||
775 | /* | |
776 | * This is a bit more difficult. We only want to add pages | |
777 | * when we can allocate enough for all CPUs. We do this | |
778 | * by allocating all the pages and storing them on a local | |
779 | * link list. If we succeed in our allocation, then we | |
780 | * add these pages to the cpu_buffers. Otherwise we just free | |
781 | * them all and return -ENOMEM; | |
782 | */ | |
554f786e SR |
783 | if (RB_WARN_ON(buffer, nr_pages <= buffer->pages)) |
784 | goto out_fail; | |
f536aafc | 785 | |
7a8e76a3 SR |
786 | new_pages = nr_pages - buffer->pages; |
787 | ||
788 | for_each_buffer_cpu(buffer, cpu) { | |
789 | for (i = 0; i < new_pages; i++) { | |
044fa782 | 790 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), |
e4c2ce82 SR |
791 | cache_line_size()), |
792 | GFP_KERNEL, cpu_to_node(cpu)); | |
044fa782 | 793 | if (!bpage) |
e4c2ce82 | 794 | goto free_pages; |
044fa782 | 795 | list_add(&bpage->list, &pages); |
7a8e76a3 SR |
796 | addr = __get_free_page(GFP_KERNEL); |
797 | if (!addr) | |
798 | goto free_pages; | |
044fa782 SR |
799 | bpage->page = (void *)addr; |
800 | rb_init_page(bpage->page); | |
7a8e76a3 SR |
801 | } |
802 | } | |
803 | ||
804 | for_each_buffer_cpu(buffer, cpu) { | |
805 | cpu_buffer = buffer->buffers[cpu]; | |
806 | rb_insert_pages(cpu_buffer, &pages, new_pages); | |
807 | } | |
808 | ||
554f786e SR |
809 | if (RB_WARN_ON(buffer, !list_empty(&pages))) |
810 | goto out_fail; | |
7a8e76a3 SR |
811 | |
812 | out: | |
813 | buffer->pages = nr_pages; | |
554f786e | 814 | put_online_cpus(); |
7a8e76a3 SR |
815 | mutex_unlock(&buffer->mutex); |
816 | ||
817 | return size; | |
818 | ||
819 | free_pages: | |
044fa782 SR |
820 | list_for_each_entry_safe(bpage, tmp, &pages, list) { |
821 | list_del_init(&bpage->list); | |
822 | free_buffer_page(bpage); | |
7a8e76a3 | 823 | } |
554f786e | 824 | put_online_cpus(); |
641d2f63 | 825 | mutex_unlock(&buffer->mutex); |
7a8e76a3 | 826 | return -ENOMEM; |
554f786e SR |
827 | |
828 | /* | |
829 | * Something went totally wrong, and we are too paranoid | |
830 | * to even clean up the mess. | |
831 | */ | |
832 | out_fail: | |
833 | put_online_cpus(); | |
834 | mutex_unlock(&buffer->mutex); | |
835 | return -1; | |
7a8e76a3 | 836 | } |
c4f50183 | 837 | EXPORT_SYMBOL_GPL(ring_buffer_resize); |
7a8e76a3 | 838 | |
7a8e76a3 SR |
839 | static inline int rb_null_event(struct ring_buffer_event *event) |
840 | { | |
841 | return event->type == RINGBUF_TYPE_PADDING; | |
842 | } | |
843 | ||
8789a9e7 | 844 | static inline void * |
044fa782 | 845 | __rb_data_page_index(struct buffer_data_page *bpage, unsigned index) |
8789a9e7 | 846 | { |
044fa782 | 847 | return bpage->data + index; |
8789a9e7 SR |
848 | } |
849 | ||
044fa782 | 850 | static inline void *__rb_page_index(struct buffer_page *bpage, unsigned index) |
7a8e76a3 | 851 | { |
044fa782 | 852 | return bpage->page->data + index; |
7a8e76a3 SR |
853 | } |
854 | ||
855 | static inline struct ring_buffer_event * | |
d769041f | 856 | rb_reader_event(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 857 | { |
6f807acd SR |
858 | return __rb_page_index(cpu_buffer->reader_page, |
859 | cpu_buffer->reader_page->read); | |
860 | } | |
861 | ||
862 | static inline struct ring_buffer_event * | |
863 | rb_head_event(struct ring_buffer_per_cpu *cpu_buffer) | |
864 | { | |
865 | return __rb_page_index(cpu_buffer->head_page, | |
866 | cpu_buffer->head_page->read); | |
7a8e76a3 SR |
867 | } |
868 | ||
869 | static inline struct ring_buffer_event * | |
870 | rb_iter_head_event(struct ring_buffer_iter *iter) | |
871 | { | |
6f807acd | 872 | return __rb_page_index(iter->head_page, iter->head); |
7a8e76a3 SR |
873 | } |
874 | ||
bf41a158 SR |
875 | static inline unsigned rb_page_write(struct buffer_page *bpage) |
876 | { | |
877 | return local_read(&bpage->write); | |
878 | } | |
879 | ||
880 | static inline unsigned rb_page_commit(struct buffer_page *bpage) | |
881 | { | |
abc9b56d | 882 | return local_read(&bpage->page->commit); |
bf41a158 SR |
883 | } |
884 | ||
885 | /* Size is determined by what has been commited */ | |
886 | static inline unsigned rb_page_size(struct buffer_page *bpage) | |
887 | { | |
888 | return rb_page_commit(bpage); | |
889 | } | |
890 | ||
891 | static inline unsigned | |
892 | rb_commit_index(struct ring_buffer_per_cpu *cpu_buffer) | |
893 | { | |
894 | return rb_page_commit(cpu_buffer->commit_page); | |
895 | } | |
896 | ||
897 | static inline unsigned rb_head_size(struct ring_buffer_per_cpu *cpu_buffer) | |
898 | { | |
899 | return rb_page_commit(cpu_buffer->head_page); | |
900 | } | |
901 | ||
7a8e76a3 SR |
902 | /* |
903 | * When the tail hits the head and the buffer is in overwrite mode, | |
904 | * the head jumps to the next page and all content on the previous | |
905 | * page is discarded. But before doing so, we update the overrun | |
906 | * variable of the buffer. | |
907 | */ | |
908 | static void rb_update_overflow(struct ring_buffer_per_cpu *cpu_buffer) | |
909 | { | |
910 | struct ring_buffer_event *event; | |
911 | unsigned long head; | |
912 | ||
913 | for (head = 0; head < rb_head_size(cpu_buffer); | |
914 | head += rb_event_length(event)) { | |
915 | ||
6f807acd | 916 | event = __rb_page_index(cpu_buffer->head_page, head); |
3e89c7bb SR |
917 | if (RB_WARN_ON(cpu_buffer, rb_null_event(event))) |
918 | return; | |
7a8e76a3 SR |
919 | /* Only count data entries */ |
920 | if (event->type != RINGBUF_TYPE_DATA) | |
921 | continue; | |
922 | cpu_buffer->overrun++; | |
923 | cpu_buffer->entries--; | |
924 | } | |
925 | } | |
926 | ||
927 | static inline void rb_inc_page(struct ring_buffer_per_cpu *cpu_buffer, | |
044fa782 | 928 | struct buffer_page **bpage) |
7a8e76a3 | 929 | { |
044fa782 | 930 | struct list_head *p = (*bpage)->list.next; |
7a8e76a3 SR |
931 | |
932 | if (p == &cpu_buffer->pages) | |
933 | p = p->next; | |
934 | ||
044fa782 | 935 | *bpage = list_entry(p, struct buffer_page, list); |
7a8e76a3 SR |
936 | } |
937 | ||
bf41a158 SR |
938 | static inline unsigned |
939 | rb_event_index(struct ring_buffer_event *event) | |
940 | { | |
941 | unsigned long addr = (unsigned long)event; | |
942 | ||
943 | return (addr & ~PAGE_MASK) - (PAGE_SIZE - BUF_PAGE_SIZE); | |
944 | } | |
945 | ||
34a148bf | 946 | static int |
bf41a158 SR |
947 | rb_is_commit(struct ring_buffer_per_cpu *cpu_buffer, |
948 | struct ring_buffer_event *event) | |
949 | { | |
950 | unsigned long addr = (unsigned long)event; | |
951 | unsigned long index; | |
952 | ||
953 | index = rb_event_index(event); | |
954 | addr &= PAGE_MASK; | |
955 | ||
956 | return cpu_buffer->commit_page->page == (void *)addr && | |
957 | rb_commit_index(cpu_buffer) == index; | |
958 | } | |
959 | ||
34a148bf | 960 | static void |
bf41a158 SR |
961 | rb_set_commit_event(struct ring_buffer_per_cpu *cpu_buffer, |
962 | struct ring_buffer_event *event) | |
7a8e76a3 | 963 | { |
bf41a158 SR |
964 | unsigned long addr = (unsigned long)event; |
965 | unsigned long index; | |
966 | ||
967 | index = rb_event_index(event); | |
968 | addr &= PAGE_MASK; | |
969 | ||
970 | while (cpu_buffer->commit_page->page != (void *)addr) { | |
3e89c7bb SR |
971 | if (RB_WARN_ON(cpu_buffer, |
972 | cpu_buffer->commit_page == cpu_buffer->tail_page)) | |
973 | return; | |
abc9b56d | 974 | cpu_buffer->commit_page->page->commit = |
bf41a158 SR |
975 | cpu_buffer->commit_page->write; |
976 | rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); | |
abc9b56d SR |
977 | cpu_buffer->write_stamp = |
978 | cpu_buffer->commit_page->page->time_stamp; | |
bf41a158 SR |
979 | } |
980 | ||
981 | /* Now set the commit to the event's index */ | |
abc9b56d | 982 | local_set(&cpu_buffer->commit_page->page->commit, index); |
7a8e76a3 SR |
983 | } |
984 | ||
34a148bf | 985 | static void |
bf41a158 | 986 | rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 987 | { |
bf41a158 SR |
988 | /* |
989 | * We only race with interrupts and NMIs on this CPU. | |
990 | * If we own the commit event, then we can commit | |
991 | * all others that interrupted us, since the interruptions | |
992 | * are in stack format (they finish before they come | |
993 | * back to us). This allows us to do a simple loop to | |
994 | * assign the commit to the tail. | |
995 | */ | |
a8ccf1d6 | 996 | again: |
bf41a158 | 997 | while (cpu_buffer->commit_page != cpu_buffer->tail_page) { |
abc9b56d | 998 | cpu_buffer->commit_page->page->commit = |
bf41a158 SR |
999 | cpu_buffer->commit_page->write; |
1000 | rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); | |
abc9b56d SR |
1001 | cpu_buffer->write_stamp = |
1002 | cpu_buffer->commit_page->page->time_stamp; | |
bf41a158 SR |
1003 | /* add barrier to keep gcc from optimizing too much */ |
1004 | barrier(); | |
1005 | } | |
1006 | while (rb_commit_index(cpu_buffer) != | |
1007 | rb_page_write(cpu_buffer->commit_page)) { | |
abc9b56d | 1008 | cpu_buffer->commit_page->page->commit = |
bf41a158 SR |
1009 | cpu_buffer->commit_page->write; |
1010 | barrier(); | |
1011 | } | |
a8ccf1d6 SR |
1012 | |
1013 | /* again, keep gcc from optimizing */ | |
1014 | barrier(); | |
1015 | ||
1016 | /* | |
1017 | * If an interrupt came in just after the first while loop | |
1018 | * and pushed the tail page forward, we will be left with | |
1019 | * a dangling commit that will never go forward. | |
1020 | */ | |
1021 | if (unlikely(cpu_buffer->commit_page != cpu_buffer->tail_page)) | |
1022 | goto again; | |
7a8e76a3 SR |
1023 | } |
1024 | ||
d769041f | 1025 | static void rb_reset_reader_page(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 1026 | { |
abc9b56d | 1027 | cpu_buffer->read_stamp = cpu_buffer->reader_page->page->time_stamp; |
6f807acd | 1028 | cpu_buffer->reader_page->read = 0; |
d769041f SR |
1029 | } |
1030 | ||
34a148bf | 1031 | static void rb_inc_iter(struct ring_buffer_iter *iter) |
d769041f SR |
1032 | { |
1033 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
1034 | ||
1035 | /* | |
1036 | * The iterator could be on the reader page (it starts there). | |
1037 | * But the head could have moved, since the reader was | |
1038 | * found. Check for this case and assign the iterator | |
1039 | * to the head page instead of next. | |
1040 | */ | |
1041 | if (iter->head_page == cpu_buffer->reader_page) | |
1042 | iter->head_page = cpu_buffer->head_page; | |
1043 | else | |
1044 | rb_inc_page(cpu_buffer, &iter->head_page); | |
1045 | ||
abc9b56d | 1046 | iter->read_stamp = iter->head_page->page->time_stamp; |
7a8e76a3 SR |
1047 | iter->head = 0; |
1048 | } | |
1049 | ||
1050 | /** | |
1051 | * ring_buffer_update_event - update event type and data | |
1052 | * @event: the even to update | |
1053 | * @type: the type of event | |
1054 | * @length: the size of the event field in the ring buffer | |
1055 | * | |
1056 | * Update the type and data fields of the event. The length | |
1057 | * is the actual size that is written to the ring buffer, | |
1058 | * and with this, we can determine what to place into the | |
1059 | * data field. | |
1060 | */ | |
34a148bf | 1061 | static void |
7a8e76a3 SR |
1062 | rb_update_event(struct ring_buffer_event *event, |
1063 | unsigned type, unsigned length) | |
1064 | { | |
1065 | event->type = type; | |
1066 | ||
1067 | switch (type) { | |
1068 | ||
1069 | case RINGBUF_TYPE_PADDING: | |
1070 | break; | |
1071 | ||
1072 | case RINGBUF_TYPE_TIME_EXTEND: | |
67d34724 | 1073 | event->len = DIV_ROUND_UP(RB_LEN_TIME_EXTEND, RB_ALIGNMENT); |
7a8e76a3 SR |
1074 | break; |
1075 | ||
1076 | case RINGBUF_TYPE_TIME_STAMP: | |
67d34724 | 1077 | event->len = DIV_ROUND_UP(RB_LEN_TIME_STAMP, RB_ALIGNMENT); |
7a8e76a3 SR |
1078 | break; |
1079 | ||
1080 | case RINGBUF_TYPE_DATA: | |
1081 | length -= RB_EVNT_HDR_SIZE; | |
1082 | if (length > RB_MAX_SMALL_DATA) { | |
1083 | event->len = 0; | |
1084 | event->array[0] = length; | |
1085 | } else | |
67d34724 | 1086 | event->len = DIV_ROUND_UP(length, RB_ALIGNMENT); |
7a8e76a3 SR |
1087 | break; |
1088 | default: | |
1089 | BUG(); | |
1090 | } | |
1091 | } | |
1092 | ||
34a148bf | 1093 | static unsigned rb_calculate_event_length(unsigned length) |
7a8e76a3 SR |
1094 | { |
1095 | struct ring_buffer_event event; /* Used only for sizeof array */ | |
1096 | ||
1097 | /* zero length can cause confusions */ | |
1098 | if (!length) | |
1099 | length = 1; | |
1100 | ||
1101 | if (length > RB_MAX_SMALL_DATA) | |
1102 | length += sizeof(event.array[0]); | |
1103 | ||
1104 | length += RB_EVNT_HDR_SIZE; | |
1105 | length = ALIGN(length, RB_ALIGNMENT); | |
1106 | ||
1107 | return length; | |
1108 | } | |
1109 | ||
1110 | static struct ring_buffer_event * | |
1111 | __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, | |
1112 | unsigned type, unsigned long length, u64 *ts) | |
1113 | { | |
98db8df7 | 1114 | struct buffer_page *tail_page, *head_page, *reader_page, *commit_page; |
bf41a158 | 1115 | unsigned long tail, write; |
7a8e76a3 SR |
1116 | struct ring_buffer *buffer = cpu_buffer->buffer; |
1117 | struct ring_buffer_event *event; | |
bf41a158 | 1118 | unsigned long flags; |
78d904b4 | 1119 | bool lock_taken = false; |
7a8e76a3 | 1120 | |
98db8df7 SR |
1121 | commit_page = cpu_buffer->commit_page; |
1122 | /* we just need to protect against interrupts */ | |
1123 | barrier(); | |
7a8e76a3 | 1124 | tail_page = cpu_buffer->tail_page; |
bf41a158 SR |
1125 | write = local_add_return(length, &tail_page->write); |
1126 | tail = write - length; | |
7a8e76a3 | 1127 | |
bf41a158 SR |
1128 | /* See if we shot pass the end of this buffer page */ |
1129 | if (write > BUF_PAGE_SIZE) { | |
7a8e76a3 SR |
1130 | struct buffer_page *next_page = tail_page; |
1131 | ||
3e03fb7f | 1132 | local_irq_save(flags); |
78d904b4 | 1133 | /* |
a81bd80a SR |
1134 | * Since the write to the buffer is still not |
1135 | * fully lockless, we must be careful with NMIs. | |
1136 | * The locks in the writers are taken when a write | |
1137 | * crosses to a new page. The locks protect against | |
1138 | * races with the readers (this will soon be fixed | |
1139 | * with a lockless solution). | |
1140 | * | |
1141 | * Because we can not protect against NMIs, and we | |
1142 | * want to keep traces reentrant, we need to manage | |
1143 | * what happens when we are in an NMI. | |
1144 | * | |
78d904b4 SR |
1145 | * NMIs can happen after we take the lock. |
1146 | * If we are in an NMI, only take the lock | |
1147 | * if it is not already taken. Otherwise | |
1148 | * simply fail. | |
1149 | */ | |
a81bd80a | 1150 | if (unlikely(in_nmi())) { |
78d904b4 | 1151 | if (!__raw_spin_trylock(&cpu_buffer->lock)) |
45141d46 | 1152 | goto out_reset; |
78d904b4 SR |
1153 | } else |
1154 | __raw_spin_lock(&cpu_buffer->lock); | |
1155 | ||
1156 | lock_taken = true; | |
bf41a158 | 1157 | |
7a8e76a3 SR |
1158 | rb_inc_page(cpu_buffer, &next_page); |
1159 | ||
d769041f SR |
1160 | head_page = cpu_buffer->head_page; |
1161 | reader_page = cpu_buffer->reader_page; | |
1162 | ||
1163 | /* we grabbed the lock before incrementing */ | |
3e89c7bb | 1164 | if (RB_WARN_ON(cpu_buffer, next_page == reader_page)) |
45141d46 | 1165 | goto out_reset; |
bf41a158 SR |
1166 | |
1167 | /* | |
1168 | * If for some reason, we had an interrupt storm that made | |
1169 | * it all the way around the buffer, bail, and warn | |
1170 | * about it. | |
1171 | */ | |
98db8df7 | 1172 | if (unlikely(next_page == commit_page)) { |
bf41a158 | 1173 | WARN_ON_ONCE(1); |
45141d46 | 1174 | goto out_reset; |
bf41a158 | 1175 | } |
d769041f | 1176 | |
7a8e76a3 | 1177 | if (next_page == head_page) { |
6f3b3440 | 1178 | if (!(buffer->flags & RB_FL_OVERWRITE)) |
45141d46 | 1179 | goto out_reset; |
7a8e76a3 | 1180 | |
bf41a158 SR |
1181 | /* tail_page has not moved yet? */ |
1182 | if (tail_page == cpu_buffer->tail_page) { | |
1183 | /* count overflows */ | |
1184 | rb_update_overflow(cpu_buffer); | |
1185 | ||
1186 | rb_inc_page(cpu_buffer, &head_page); | |
1187 | cpu_buffer->head_page = head_page; | |
1188 | cpu_buffer->head_page->read = 0; | |
1189 | } | |
1190 | } | |
7a8e76a3 | 1191 | |
bf41a158 SR |
1192 | /* |
1193 | * If the tail page is still the same as what we think | |
1194 | * it is, then it is up to us to update the tail | |
1195 | * pointer. | |
1196 | */ | |
1197 | if (tail_page == cpu_buffer->tail_page) { | |
1198 | local_set(&next_page->write, 0); | |
abc9b56d | 1199 | local_set(&next_page->page->commit, 0); |
bf41a158 SR |
1200 | cpu_buffer->tail_page = next_page; |
1201 | ||
1202 | /* reread the time stamp */ | |
37886f6a | 1203 | *ts = ring_buffer_time_stamp(buffer, cpu_buffer->cpu); |
abc9b56d | 1204 | cpu_buffer->tail_page->page->time_stamp = *ts; |
7a8e76a3 SR |
1205 | } |
1206 | ||
bf41a158 SR |
1207 | /* |
1208 | * The actual tail page has moved forward. | |
1209 | */ | |
1210 | if (tail < BUF_PAGE_SIZE) { | |
1211 | /* Mark the rest of the page with padding */ | |
6f807acd | 1212 | event = __rb_page_index(tail_page, tail); |
7a8e76a3 SR |
1213 | event->type = RINGBUF_TYPE_PADDING; |
1214 | } | |
1215 | ||
bf41a158 SR |
1216 | if (tail <= BUF_PAGE_SIZE) |
1217 | /* Set the write back to the previous setting */ | |
1218 | local_set(&tail_page->write, tail); | |
1219 | ||
1220 | /* | |
1221 | * If this was a commit entry that failed, | |
1222 | * increment that too | |
1223 | */ | |
1224 | if (tail_page == cpu_buffer->commit_page && | |
1225 | tail == rb_commit_index(cpu_buffer)) { | |
1226 | rb_set_commit_to_write(cpu_buffer); | |
1227 | } | |
1228 | ||
3e03fb7f SR |
1229 | __raw_spin_unlock(&cpu_buffer->lock); |
1230 | local_irq_restore(flags); | |
bf41a158 SR |
1231 | |
1232 | /* fail and let the caller try again */ | |
1233 | return ERR_PTR(-EAGAIN); | |
7a8e76a3 SR |
1234 | } |
1235 | ||
bf41a158 SR |
1236 | /* We reserved something on the buffer */ |
1237 | ||
3e89c7bb SR |
1238 | if (RB_WARN_ON(cpu_buffer, write > BUF_PAGE_SIZE)) |
1239 | return NULL; | |
7a8e76a3 | 1240 | |
6f807acd | 1241 | event = __rb_page_index(tail_page, tail); |
7a8e76a3 SR |
1242 | rb_update_event(event, type, length); |
1243 | ||
bf41a158 SR |
1244 | /* |
1245 | * If this is a commit and the tail is zero, then update | |
1246 | * this page's time stamp. | |
1247 | */ | |
1248 | if (!tail && rb_is_commit(cpu_buffer, event)) | |
abc9b56d | 1249 | cpu_buffer->commit_page->page->time_stamp = *ts; |
bf41a158 | 1250 | |
7a8e76a3 | 1251 | return event; |
bf41a158 | 1252 | |
45141d46 | 1253 | out_reset: |
6f3b3440 LJ |
1254 | /* reset write */ |
1255 | if (tail <= BUF_PAGE_SIZE) | |
1256 | local_set(&tail_page->write, tail); | |
1257 | ||
78d904b4 SR |
1258 | if (likely(lock_taken)) |
1259 | __raw_spin_unlock(&cpu_buffer->lock); | |
3e03fb7f | 1260 | local_irq_restore(flags); |
bf41a158 | 1261 | return NULL; |
7a8e76a3 SR |
1262 | } |
1263 | ||
1264 | static int | |
1265 | rb_add_time_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
1266 | u64 *ts, u64 *delta) | |
1267 | { | |
1268 | struct ring_buffer_event *event; | |
1269 | static int once; | |
bf41a158 | 1270 | int ret; |
7a8e76a3 SR |
1271 | |
1272 | if (unlikely(*delta > (1ULL << 59) && !once++)) { | |
1273 | printk(KERN_WARNING "Delta way too big! %llu" | |
1274 | " ts=%llu write stamp = %llu\n", | |
e2862c94 SR |
1275 | (unsigned long long)*delta, |
1276 | (unsigned long long)*ts, | |
1277 | (unsigned long long)cpu_buffer->write_stamp); | |
7a8e76a3 SR |
1278 | WARN_ON(1); |
1279 | } | |
1280 | ||
1281 | /* | |
1282 | * The delta is too big, we to add a | |
1283 | * new timestamp. | |
1284 | */ | |
1285 | event = __rb_reserve_next(cpu_buffer, | |
1286 | RINGBUF_TYPE_TIME_EXTEND, | |
1287 | RB_LEN_TIME_EXTEND, | |
1288 | ts); | |
1289 | if (!event) | |
bf41a158 | 1290 | return -EBUSY; |
7a8e76a3 | 1291 | |
bf41a158 SR |
1292 | if (PTR_ERR(event) == -EAGAIN) |
1293 | return -EAGAIN; | |
1294 | ||
1295 | /* Only a commited time event can update the write stamp */ | |
1296 | if (rb_is_commit(cpu_buffer, event)) { | |
1297 | /* | |
1298 | * If this is the first on the page, then we need to | |
1299 | * update the page itself, and just put in a zero. | |
1300 | */ | |
1301 | if (rb_event_index(event)) { | |
1302 | event->time_delta = *delta & TS_MASK; | |
1303 | event->array[0] = *delta >> TS_SHIFT; | |
1304 | } else { | |
abc9b56d | 1305 | cpu_buffer->commit_page->page->time_stamp = *ts; |
bf41a158 SR |
1306 | event->time_delta = 0; |
1307 | event->array[0] = 0; | |
1308 | } | |
7a8e76a3 | 1309 | cpu_buffer->write_stamp = *ts; |
bf41a158 SR |
1310 | /* let the caller know this was the commit */ |
1311 | ret = 1; | |
1312 | } else { | |
1313 | /* Darn, this is just wasted space */ | |
1314 | event->time_delta = 0; | |
1315 | event->array[0] = 0; | |
1316 | ret = 0; | |
7a8e76a3 SR |
1317 | } |
1318 | ||
bf41a158 SR |
1319 | *delta = 0; |
1320 | ||
1321 | return ret; | |
7a8e76a3 SR |
1322 | } |
1323 | ||
1324 | static struct ring_buffer_event * | |
1325 | rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer, | |
1326 | unsigned type, unsigned long length) | |
1327 | { | |
1328 | struct ring_buffer_event *event; | |
1329 | u64 ts, delta; | |
bf41a158 | 1330 | int commit = 0; |
818e3dd3 | 1331 | int nr_loops = 0; |
7a8e76a3 | 1332 | |
bf41a158 | 1333 | again: |
818e3dd3 SR |
1334 | /* |
1335 | * We allow for interrupts to reenter here and do a trace. | |
1336 | * If one does, it will cause this original code to loop | |
1337 | * back here. Even with heavy interrupts happening, this | |
1338 | * should only happen a few times in a row. If this happens | |
1339 | * 1000 times in a row, there must be either an interrupt | |
1340 | * storm or we have something buggy. | |
1341 | * Bail! | |
1342 | */ | |
3e89c7bb | 1343 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000)) |
818e3dd3 | 1344 | return NULL; |
818e3dd3 | 1345 | |
37886f6a | 1346 | ts = ring_buffer_time_stamp(cpu_buffer->buffer, cpu_buffer->cpu); |
7a8e76a3 | 1347 | |
bf41a158 SR |
1348 | /* |
1349 | * Only the first commit can update the timestamp. | |
1350 | * Yes there is a race here. If an interrupt comes in | |
1351 | * just after the conditional and it traces too, then it | |
1352 | * will also check the deltas. More than one timestamp may | |
1353 | * also be made. But only the entry that did the actual | |
1354 | * commit will be something other than zero. | |
1355 | */ | |
1356 | if (cpu_buffer->tail_page == cpu_buffer->commit_page && | |
1357 | rb_page_write(cpu_buffer->tail_page) == | |
1358 | rb_commit_index(cpu_buffer)) { | |
1359 | ||
7a8e76a3 SR |
1360 | delta = ts - cpu_buffer->write_stamp; |
1361 | ||
bf41a158 SR |
1362 | /* make sure this delta is calculated here */ |
1363 | barrier(); | |
1364 | ||
1365 | /* Did the write stamp get updated already? */ | |
1366 | if (unlikely(ts < cpu_buffer->write_stamp)) | |
4143c5cb | 1367 | delta = 0; |
bf41a158 | 1368 | |
7a8e76a3 | 1369 | if (test_time_stamp(delta)) { |
7a8e76a3 | 1370 | |
bf41a158 SR |
1371 | commit = rb_add_time_stamp(cpu_buffer, &ts, &delta); |
1372 | ||
1373 | if (commit == -EBUSY) | |
7a8e76a3 | 1374 | return NULL; |
bf41a158 SR |
1375 | |
1376 | if (commit == -EAGAIN) | |
1377 | goto again; | |
1378 | ||
1379 | RB_WARN_ON(cpu_buffer, commit < 0); | |
7a8e76a3 | 1380 | } |
bf41a158 SR |
1381 | } else |
1382 | /* Non commits have zero deltas */ | |
7a8e76a3 | 1383 | delta = 0; |
7a8e76a3 SR |
1384 | |
1385 | event = __rb_reserve_next(cpu_buffer, type, length, &ts); | |
bf41a158 SR |
1386 | if (PTR_ERR(event) == -EAGAIN) |
1387 | goto again; | |
1388 | ||
1389 | if (!event) { | |
1390 | if (unlikely(commit)) | |
1391 | /* | |
1392 | * Ouch! We needed a timestamp and it was commited. But | |
1393 | * we didn't get our event reserved. | |
1394 | */ | |
1395 | rb_set_commit_to_write(cpu_buffer); | |
7a8e76a3 | 1396 | return NULL; |
bf41a158 | 1397 | } |
7a8e76a3 | 1398 | |
bf41a158 SR |
1399 | /* |
1400 | * If the timestamp was commited, make the commit our entry | |
1401 | * now so that we will update it when needed. | |
1402 | */ | |
1403 | if (commit) | |
1404 | rb_set_commit_event(cpu_buffer, event); | |
1405 | else if (!rb_is_commit(cpu_buffer, event)) | |
7a8e76a3 SR |
1406 | delta = 0; |
1407 | ||
1408 | event->time_delta = delta; | |
1409 | ||
1410 | return event; | |
1411 | } | |
1412 | ||
bf41a158 SR |
1413 | static DEFINE_PER_CPU(int, rb_need_resched); |
1414 | ||
7a8e76a3 SR |
1415 | /** |
1416 | * ring_buffer_lock_reserve - reserve a part of the buffer | |
1417 | * @buffer: the ring buffer to reserve from | |
1418 | * @length: the length of the data to reserve (excluding event header) | |
7a8e76a3 SR |
1419 | * |
1420 | * Returns a reseverd event on the ring buffer to copy directly to. | |
1421 | * The user of this interface will need to get the body to write into | |
1422 | * and can use the ring_buffer_event_data() interface. | |
1423 | * | |
1424 | * The length is the length of the data needed, not the event length | |
1425 | * which also includes the event header. | |
1426 | * | |
1427 | * Must be paired with ring_buffer_unlock_commit, unless NULL is returned. | |
1428 | * If NULL is returned, then nothing has been allocated or locked. | |
1429 | */ | |
1430 | struct ring_buffer_event * | |
0a987751 | 1431 | ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length) |
7a8e76a3 SR |
1432 | { |
1433 | struct ring_buffer_per_cpu *cpu_buffer; | |
1434 | struct ring_buffer_event *event; | |
bf41a158 | 1435 | int cpu, resched; |
7a8e76a3 | 1436 | |
033601a3 | 1437 | if (ring_buffer_flags != RB_BUFFERS_ON) |
a3583244 SR |
1438 | return NULL; |
1439 | ||
7a8e76a3 SR |
1440 | if (atomic_read(&buffer->record_disabled)) |
1441 | return NULL; | |
1442 | ||
bf41a158 | 1443 | /* If we are tracing schedule, we don't want to recurse */ |
182e9f5f | 1444 | resched = ftrace_preempt_disable(); |
bf41a158 | 1445 | |
7a8e76a3 SR |
1446 | cpu = raw_smp_processor_id(); |
1447 | ||
9e01c1b7 | 1448 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
d769041f | 1449 | goto out; |
7a8e76a3 SR |
1450 | |
1451 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 SR |
1452 | |
1453 | if (atomic_read(&cpu_buffer->record_disabled)) | |
d769041f | 1454 | goto out; |
7a8e76a3 SR |
1455 | |
1456 | length = rb_calculate_event_length(length); | |
1457 | if (length > BUF_PAGE_SIZE) | |
bf41a158 | 1458 | goto out; |
7a8e76a3 SR |
1459 | |
1460 | event = rb_reserve_next_event(cpu_buffer, RINGBUF_TYPE_DATA, length); | |
1461 | if (!event) | |
d769041f | 1462 | goto out; |
7a8e76a3 | 1463 | |
bf41a158 SR |
1464 | /* |
1465 | * Need to store resched state on this cpu. | |
1466 | * Only the first needs to. | |
1467 | */ | |
1468 | ||
1469 | if (preempt_count() == 1) | |
1470 | per_cpu(rb_need_resched, cpu) = resched; | |
1471 | ||
7a8e76a3 SR |
1472 | return event; |
1473 | ||
d769041f | 1474 | out: |
182e9f5f | 1475 | ftrace_preempt_enable(resched); |
7a8e76a3 SR |
1476 | return NULL; |
1477 | } | |
c4f50183 | 1478 | EXPORT_SYMBOL_GPL(ring_buffer_lock_reserve); |
7a8e76a3 SR |
1479 | |
1480 | static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, | |
1481 | struct ring_buffer_event *event) | |
1482 | { | |
7a8e76a3 | 1483 | cpu_buffer->entries++; |
bf41a158 SR |
1484 | |
1485 | /* Only process further if we own the commit */ | |
1486 | if (!rb_is_commit(cpu_buffer, event)) | |
1487 | return; | |
1488 | ||
1489 | cpu_buffer->write_stamp += event->time_delta; | |
1490 | ||
1491 | rb_set_commit_to_write(cpu_buffer); | |
7a8e76a3 SR |
1492 | } |
1493 | ||
1494 | /** | |
1495 | * ring_buffer_unlock_commit - commit a reserved | |
1496 | * @buffer: The buffer to commit to | |
1497 | * @event: The event pointer to commit. | |
7a8e76a3 SR |
1498 | * |
1499 | * This commits the data to the ring buffer, and releases any locks held. | |
1500 | * | |
1501 | * Must be paired with ring_buffer_lock_reserve. | |
1502 | */ | |
1503 | int ring_buffer_unlock_commit(struct ring_buffer *buffer, | |
0a987751 | 1504 | struct ring_buffer_event *event) |
7a8e76a3 SR |
1505 | { |
1506 | struct ring_buffer_per_cpu *cpu_buffer; | |
1507 | int cpu = raw_smp_processor_id(); | |
1508 | ||
1509 | cpu_buffer = buffer->buffers[cpu]; | |
1510 | ||
7a8e76a3 SR |
1511 | rb_commit(cpu_buffer, event); |
1512 | ||
bf41a158 SR |
1513 | /* |
1514 | * Only the last preempt count needs to restore preemption. | |
1515 | */ | |
182e9f5f SR |
1516 | if (preempt_count() == 1) |
1517 | ftrace_preempt_enable(per_cpu(rb_need_resched, cpu)); | |
1518 | else | |
bf41a158 | 1519 | preempt_enable_no_resched_notrace(); |
7a8e76a3 SR |
1520 | |
1521 | return 0; | |
1522 | } | |
c4f50183 | 1523 | EXPORT_SYMBOL_GPL(ring_buffer_unlock_commit); |
7a8e76a3 SR |
1524 | |
1525 | /** | |
1526 | * ring_buffer_write - write data to the buffer without reserving | |
1527 | * @buffer: The ring buffer to write to. | |
1528 | * @length: The length of the data being written (excluding the event header) | |
1529 | * @data: The data to write to the buffer. | |
1530 | * | |
1531 | * This is like ring_buffer_lock_reserve and ring_buffer_unlock_commit as | |
1532 | * one function. If you already have the data to write to the buffer, it | |
1533 | * may be easier to simply call this function. | |
1534 | * | |
1535 | * Note, like ring_buffer_lock_reserve, the length is the length of the data | |
1536 | * and not the length of the event which would hold the header. | |
1537 | */ | |
1538 | int ring_buffer_write(struct ring_buffer *buffer, | |
1539 | unsigned long length, | |
1540 | void *data) | |
1541 | { | |
1542 | struct ring_buffer_per_cpu *cpu_buffer; | |
1543 | struct ring_buffer_event *event; | |
bf41a158 | 1544 | unsigned long event_length; |
7a8e76a3 SR |
1545 | void *body; |
1546 | int ret = -EBUSY; | |
bf41a158 | 1547 | int cpu, resched; |
7a8e76a3 | 1548 | |
033601a3 | 1549 | if (ring_buffer_flags != RB_BUFFERS_ON) |
a3583244 SR |
1550 | return -EBUSY; |
1551 | ||
7a8e76a3 SR |
1552 | if (atomic_read(&buffer->record_disabled)) |
1553 | return -EBUSY; | |
1554 | ||
182e9f5f | 1555 | resched = ftrace_preempt_disable(); |
bf41a158 | 1556 | |
7a8e76a3 SR |
1557 | cpu = raw_smp_processor_id(); |
1558 | ||
9e01c1b7 | 1559 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
d769041f | 1560 | goto out; |
7a8e76a3 SR |
1561 | |
1562 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 SR |
1563 | |
1564 | if (atomic_read(&cpu_buffer->record_disabled)) | |
1565 | goto out; | |
1566 | ||
1567 | event_length = rb_calculate_event_length(length); | |
1568 | event = rb_reserve_next_event(cpu_buffer, | |
1569 | RINGBUF_TYPE_DATA, event_length); | |
1570 | if (!event) | |
1571 | goto out; | |
1572 | ||
1573 | body = rb_event_data(event); | |
1574 | ||
1575 | memcpy(body, data, length); | |
1576 | ||
1577 | rb_commit(cpu_buffer, event); | |
1578 | ||
1579 | ret = 0; | |
1580 | out: | |
182e9f5f | 1581 | ftrace_preempt_enable(resched); |
7a8e76a3 SR |
1582 | |
1583 | return ret; | |
1584 | } | |
c4f50183 | 1585 | EXPORT_SYMBOL_GPL(ring_buffer_write); |
7a8e76a3 | 1586 | |
34a148bf | 1587 | static int rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) |
bf41a158 SR |
1588 | { |
1589 | struct buffer_page *reader = cpu_buffer->reader_page; | |
1590 | struct buffer_page *head = cpu_buffer->head_page; | |
1591 | struct buffer_page *commit = cpu_buffer->commit_page; | |
1592 | ||
1593 | return reader->read == rb_page_commit(reader) && | |
1594 | (commit == reader || | |
1595 | (commit == head && | |
1596 | head->read == rb_page_commit(commit))); | |
1597 | } | |
1598 | ||
7a8e76a3 SR |
1599 | /** |
1600 | * ring_buffer_record_disable - stop all writes into the buffer | |
1601 | * @buffer: The ring buffer to stop writes to. | |
1602 | * | |
1603 | * This prevents all writes to the buffer. Any attempt to write | |
1604 | * to the buffer after this will fail and return NULL. | |
1605 | * | |
1606 | * The caller should call synchronize_sched() after this. | |
1607 | */ | |
1608 | void ring_buffer_record_disable(struct ring_buffer *buffer) | |
1609 | { | |
1610 | atomic_inc(&buffer->record_disabled); | |
1611 | } | |
c4f50183 | 1612 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable); |
7a8e76a3 SR |
1613 | |
1614 | /** | |
1615 | * ring_buffer_record_enable - enable writes to the buffer | |
1616 | * @buffer: The ring buffer to enable writes | |
1617 | * | |
1618 | * Note, multiple disables will need the same number of enables | |
1619 | * to truely enable the writing (much like preempt_disable). | |
1620 | */ | |
1621 | void ring_buffer_record_enable(struct ring_buffer *buffer) | |
1622 | { | |
1623 | atomic_dec(&buffer->record_disabled); | |
1624 | } | |
c4f50183 | 1625 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable); |
7a8e76a3 SR |
1626 | |
1627 | /** | |
1628 | * ring_buffer_record_disable_cpu - stop all writes into the cpu_buffer | |
1629 | * @buffer: The ring buffer to stop writes to. | |
1630 | * @cpu: The CPU buffer to stop | |
1631 | * | |
1632 | * This prevents all writes to the buffer. Any attempt to write | |
1633 | * to the buffer after this will fail and return NULL. | |
1634 | * | |
1635 | * The caller should call synchronize_sched() after this. | |
1636 | */ | |
1637 | void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu) | |
1638 | { | |
1639 | struct ring_buffer_per_cpu *cpu_buffer; | |
1640 | ||
9e01c1b7 | 1641 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 1642 | return; |
7a8e76a3 SR |
1643 | |
1644 | cpu_buffer = buffer->buffers[cpu]; | |
1645 | atomic_inc(&cpu_buffer->record_disabled); | |
1646 | } | |
c4f50183 | 1647 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable_cpu); |
7a8e76a3 SR |
1648 | |
1649 | /** | |
1650 | * ring_buffer_record_enable_cpu - enable writes to the buffer | |
1651 | * @buffer: The ring buffer to enable writes | |
1652 | * @cpu: The CPU to enable. | |
1653 | * | |
1654 | * Note, multiple disables will need the same number of enables | |
1655 | * to truely enable the writing (much like preempt_disable). | |
1656 | */ | |
1657 | void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu) | |
1658 | { | |
1659 | struct ring_buffer_per_cpu *cpu_buffer; | |
1660 | ||
9e01c1b7 | 1661 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 1662 | return; |
7a8e76a3 SR |
1663 | |
1664 | cpu_buffer = buffer->buffers[cpu]; | |
1665 | atomic_dec(&cpu_buffer->record_disabled); | |
1666 | } | |
c4f50183 | 1667 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu); |
7a8e76a3 SR |
1668 | |
1669 | /** | |
1670 | * ring_buffer_entries_cpu - get the number of entries in a cpu buffer | |
1671 | * @buffer: The ring buffer | |
1672 | * @cpu: The per CPU buffer to get the entries from. | |
1673 | */ | |
1674 | unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu) | |
1675 | { | |
1676 | struct ring_buffer_per_cpu *cpu_buffer; | |
8aabee57 | 1677 | unsigned long ret; |
7a8e76a3 | 1678 | |
9e01c1b7 | 1679 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 1680 | return 0; |
7a8e76a3 SR |
1681 | |
1682 | cpu_buffer = buffer->buffers[cpu]; | |
554f786e | 1683 | ret = cpu_buffer->entries; |
554f786e SR |
1684 | |
1685 | return ret; | |
7a8e76a3 | 1686 | } |
c4f50183 | 1687 | EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu); |
7a8e76a3 SR |
1688 | |
1689 | /** | |
1690 | * ring_buffer_overrun_cpu - get the number of overruns in a cpu_buffer | |
1691 | * @buffer: The ring buffer | |
1692 | * @cpu: The per CPU buffer to get the number of overruns from | |
1693 | */ | |
1694 | unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu) | |
1695 | { | |
1696 | struct ring_buffer_per_cpu *cpu_buffer; | |
8aabee57 | 1697 | unsigned long ret; |
7a8e76a3 | 1698 | |
9e01c1b7 | 1699 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 1700 | return 0; |
7a8e76a3 SR |
1701 | |
1702 | cpu_buffer = buffer->buffers[cpu]; | |
554f786e | 1703 | ret = cpu_buffer->overrun; |
554f786e SR |
1704 | |
1705 | return ret; | |
7a8e76a3 | 1706 | } |
c4f50183 | 1707 | EXPORT_SYMBOL_GPL(ring_buffer_overrun_cpu); |
7a8e76a3 SR |
1708 | |
1709 | /** | |
1710 | * ring_buffer_entries - get the number of entries in a buffer | |
1711 | * @buffer: The ring buffer | |
1712 | * | |
1713 | * Returns the total number of entries in the ring buffer | |
1714 | * (all CPU entries) | |
1715 | */ | |
1716 | unsigned long ring_buffer_entries(struct ring_buffer *buffer) | |
1717 | { | |
1718 | struct ring_buffer_per_cpu *cpu_buffer; | |
1719 | unsigned long entries = 0; | |
1720 | int cpu; | |
1721 | ||
1722 | /* if you care about this being correct, lock the buffer */ | |
1723 | for_each_buffer_cpu(buffer, cpu) { | |
1724 | cpu_buffer = buffer->buffers[cpu]; | |
1725 | entries += cpu_buffer->entries; | |
1726 | } | |
1727 | ||
1728 | return entries; | |
1729 | } | |
c4f50183 | 1730 | EXPORT_SYMBOL_GPL(ring_buffer_entries); |
7a8e76a3 SR |
1731 | |
1732 | /** | |
1733 | * ring_buffer_overrun_cpu - get the number of overruns in buffer | |
1734 | * @buffer: The ring buffer | |
1735 | * | |
1736 | * Returns the total number of overruns in the ring buffer | |
1737 | * (all CPU entries) | |
1738 | */ | |
1739 | unsigned long ring_buffer_overruns(struct ring_buffer *buffer) | |
1740 | { | |
1741 | struct ring_buffer_per_cpu *cpu_buffer; | |
1742 | unsigned long overruns = 0; | |
1743 | int cpu; | |
1744 | ||
1745 | /* if you care about this being correct, lock the buffer */ | |
1746 | for_each_buffer_cpu(buffer, cpu) { | |
1747 | cpu_buffer = buffer->buffers[cpu]; | |
1748 | overruns += cpu_buffer->overrun; | |
1749 | } | |
1750 | ||
1751 | return overruns; | |
1752 | } | |
c4f50183 | 1753 | EXPORT_SYMBOL_GPL(ring_buffer_overruns); |
7a8e76a3 | 1754 | |
642edba5 | 1755 | static void rb_iter_reset(struct ring_buffer_iter *iter) |
7a8e76a3 SR |
1756 | { |
1757 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
1758 | ||
d769041f SR |
1759 | /* Iterator usage is expected to have record disabled */ |
1760 | if (list_empty(&cpu_buffer->reader_page->list)) { | |
1761 | iter->head_page = cpu_buffer->head_page; | |
6f807acd | 1762 | iter->head = cpu_buffer->head_page->read; |
d769041f SR |
1763 | } else { |
1764 | iter->head_page = cpu_buffer->reader_page; | |
6f807acd | 1765 | iter->head = cpu_buffer->reader_page->read; |
d769041f SR |
1766 | } |
1767 | if (iter->head) | |
1768 | iter->read_stamp = cpu_buffer->read_stamp; | |
1769 | else | |
abc9b56d | 1770 | iter->read_stamp = iter->head_page->page->time_stamp; |
642edba5 | 1771 | } |
f83c9d0f | 1772 | |
642edba5 SR |
1773 | /** |
1774 | * ring_buffer_iter_reset - reset an iterator | |
1775 | * @iter: The iterator to reset | |
1776 | * | |
1777 | * Resets the iterator, so that it will start from the beginning | |
1778 | * again. | |
1779 | */ | |
1780 | void ring_buffer_iter_reset(struct ring_buffer_iter *iter) | |
1781 | { | |
554f786e | 1782 | struct ring_buffer_per_cpu *cpu_buffer; |
642edba5 SR |
1783 | unsigned long flags; |
1784 | ||
554f786e SR |
1785 | if (!iter) |
1786 | return; | |
1787 | ||
1788 | cpu_buffer = iter->cpu_buffer; | |
1789 | ||
642edba5 SR |
1790 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
1791 | rb_iter_reset(iter); | |
f83c9d0f | 1792 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
7a8e76a3 | 1793 | } |
c4f50183 | 1794 | EXPORT_SYMBOL_GPL(ring_buffer_iter_reset); |
7a8e76a3 SR |
1795 | |
1796 | /** | |
1797 | * ring_buffer_iter_empty - check if an iterator has no more to read | |
1798 | * @iter: The iterator to check | |
1799 | */ | |
1800 | int ring_buffer_iter_empty(struct ring_buffer_iter *iter) | |
1801 | { | |
1802 | struct ring_buffer_per_cpu *cpu_buffer; | |
1803 | ||
1804 | cpu_buffer = iter->cpu_buffer; | |
1805 | ||
bf41a158 SR |
1806 | return iter->head_page == cpu_buffer->commit_page && |
1807 | iter->head == rb_commit_index(cpu_buffer); | |
7a8e76a3 | 1808 | } |
c4f50183 | 1809 | EXPORT_SYMBOL_GPL(ring_buffer_iter_empty); |
7a8e76a3 SR |
1810 | |
1811 | static void | |
1812 | rb_update_read_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
1813 | struct ring_buffer_event *event) | |
1814 | { | |
1815 | u64 delta; | |
1816 | ||
1817 | switch (event->type) { | |
1818 | case RINGBUF_TYPE_PADDING: | |
1819 | return; | |
1820 | ||
1821 | case RINGBUF_TYPE_TIME_EXTEND: | |
1822 | delta = event->array[0]; | |
1823 | delta <<= TS_SHIFT; | |
1824 | delta += event->time_delta; | |
1825 | cpu_buffer->read_stamp += delta; | |
1826 | return; | |
1827 | ||
1828 | case RINGBUF_TYPE_TIME_STAMP: | |
1829 | /* FIXME: not implemented */ | |
1830 | return; | |
1831 | ||
1832 | case RINGBUF_TYPE_DATA: | |
1833 | cpu_buffer->read_stamp += event->time_delta; | |
1834 | return; | |
1835 | ||
1836 | default: | |
1837 | BUG(); | |
1838 | } | |
1839 | return; | |
1840 | } | |
1841 | ||
1842 | static void | |
1843 | rb_update_iter_read_stamp(struct ring_buffer_iter *iter, | |
1844 | struct ring_buffer_event *event) | |
1845 | { | |
1846 | u64 delta; | |
1847 | ||
1848 | switch (event->type) { | |
1849 | case RINGBUF_TYPE_PADDING: | |
1850 | return; | |
1851 | ||
1852 | case RINGBUF_TYPE_TIME_EXTEND: | |
1853 | delta = event->array[0]; | |
1854 | delta <<= TS_SHIFT; | |
1855 | delta += event->time_delta; | |
1856 | iter->read_stamp += delta; | |
1857 | return; | |
1858 | ||
1859 | case RINGBUF_TYPE_TIME_STAMP: | |
1860 | /* FIXME: not implemented */ | |
1861 | return; | |
1862 | ||
1863 | case RINGBUF_TYPE_DATA: | |
1864 | iter->read_stamp += event->time_delta; | |
1865 | return; | |
1866 | ||
1867 | default: | |
1868 | BUG(); | |
1869 | } | |
1870 | return; | |
1871 | } | |
1872 | ||
d769041f SR |
1873 | static struct buffer_page * |
1874 | rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) | |
7a8e76a3 | 1875 | { |
d769041f SR |
1876 | struct buffer_page *reader = NULL; |
1877 | unsigned long flags; | |
818e3dd3 | 1878 | int nr_loops = 0; |
d769041f | 1879 | |
3e03fb7f SR |
1880 | local_irq_save(flags); |
1881 | __raw_spin_lock(&cpu_buffer->lock); | |
d769041f SR |
1882 | |
1883 | again: | |
818e3dd3 SR |
1884 | /* |
1885 | * This should normally only loop twice. But because the | |
1886 | * start of the reader inserts an empty page, it causes | |
1887 | * a case where we will loop three times. There should be no | |
1888 | * reason to loop four times (that I know of). | |
1889 | */ | |
3e89c7bb | 1890 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 3)) { |
818e3dd3 SR |
1891 | reader = NULL; |
1892 | goto out; | |
1893 | } | |
1894 | ||
d769041f SR |
1895 | reader = cpu_buffer->reader_page; |
1896 | ||
1897 | /* If there's more to read, return this page */ | |
bf41a158 | 1898 | if (cpu_buffer->reader_page->read < rb_page_size(reader)) |
d769041f SR |
1899 | goto out; |
1900 | ||
1901 | /* Never should we have an index greater than the size */ | |
3e89c7bb SR |
1902 | if (RB_WARN_ON(cpu_buffer, |
1903 | cpu_buffer->reader_page->read > rb_page_size(reader))) | |
1904 | goto out; | |
d769041f SR |
1905 | |
1906 | /* check if we caught up to the tail */ | |
1907 | reader = NULL; | |
bf41a158 | 1908 | if (cpu_buffer->commit_page == cpu_buffer->reader_page) |
d769041f | 1909 | goto out; |
7a8e76a3 SR |
1910 | |
1911 | /* | |
d769041f SR |
1912 | * Splice the empty reader page into the list around the head. |
1913 | * Reset the reader page to size zero. | |
7a8e76a3 | 1914 | */ |
7a8e76a3 | 1915 | |
d769041f SR |
1916 | reader = cpu_buffer->head_page; |
1917 | cpu_buffer->reader_page->list.next = reader->list.next; | |
1918 | cpu_buffer->reader_page->list.prev = reader->list.prev; | |
bf41a158 SR |
1919 | |
1920 | local_set(&cpu_buffer->reader_page->write, 0); | |
abc9b56d | 1921 | local_set(&cpu_buffer->reader_page->page->commit, 0); |
7a8e76a3 | 1922 | |
d769041f SR |
1923 | /* Make the reader page now replace the head */ |
1924 | reader->list.prev->next = &cpu_buffer->reader_page->list; | |
1925 | reader->list.next->prev = &cpu_buffer->reader_page->list; | |
7a8e76a3 SR |
1926 | |
1927 | /* | |
d769041f SR |
1928 | * If the tail is on the reader, then we must set the head |
1929 | * to the inserted page, otherwise we set it one before. | |
7a8e76a3 | 1930 | */ |
d769041f | 1931 | cpu_buffer->head_page = cpu_buffer->reader_page; |
7a8e76a3 | 1932 | |
bf41a158 | 1933 | if (cpu_buffer->commit_page != reader) |
d769041f SR |
1934 | rb_inc_page(cpu_buffer, &cpu_buffer->head_page); |
1935 | ||
1936 | /* Finally update the reader page to the new head */ | |
1937 | cpu_buffer->reader_page = reader; | |
1938 | rb_reset_reader_page(cpu_buffer); | |
1939 | ||
1940 | goto again; | |
1941 | ||
1942 | out: | |
3e03fb7f SR |
1943 | __raw_spin_unlock(&cpu_buffer->lock); |
1944 | local_irq_restore(flags); | |
d769041f SR |
1945 | |
1946 | return reader; | |
1947 | } | |
1948 | ||
1949 | static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer) | |
1950 | { | |
1951 | struct ring_buffer_event *event; | |
1952 | struct buffer_page *reader; | |
1953 | unsigned length; | |
1954 | ||
1955 | reader = rb_get_reader_page(cpu_buffer); | |
7a8e76a3 | 1956 | |
d769041f | 1957 | /* This function should not be called when buffer is empty */ |
3e89c7bb SR |
1958 | if (RB_WARN_ON(cpu_buffer, !reader)) |
1959 | return; | |
7a8e76a3 | 1960 | |
d769041f SR |
1961 | event = rb_reader_event(cpu_buffer); |
1962 | ||
1963 | if (event->type == RINGBUF_TYPE_DATA) | |
1964 | cpu_buffer->entries--; | |
1965 | ||
1966 | rb_update_read_stamp(cpu_buffer, event); | |
1967 | ||
1968 | length = rb_event_length(event); | |
6f807acd | 1969 | cpu_buffer->reader_page->read += length; |
7a8e76a3 SR |
1970 | } |
1971 | ||
1972 | static void rb_advance_iter(struct ring_buffer_iter *iter) | |
1973 | { | |
1974 | struct ring_buffer *buffer; | |
1975 | struct ring_buffer_per_cpu *cpu_buffer; | |
1976 | struct ring_buffer_event *event; | |
1977 | unsigned length; | |
1978 | ||
1979 | cpu_buffer = iter->cpu_buffer; | |
1980 | buffer = cpu_buffer->buffer; | |
1981 | ||
1982 | /* | |
1983 | * Check if we are at the end of the buffer. | |
1984 | */ | |
bf41a158 | 1985 | if (iter->head >= rb_page_size(iter->head_page)) { |
3e89c7bb SR |
1986 | if (RB_WARN_ON(buffer, |
1987 | iter->head_page == cpu_buffer->commit_page)) | |
1988 | return; | |
d769041f | 1989 | rb_inc_iter(iter); |
7a8e76a3 SR |
1990 | return; |
1991 | } | |
1992 | ||
1993 | event = rb_iter_head_event(iter); | |
1994 | ||
1995 | length = rb_event_length(event); | |
1996 | ||
1997 | /* | |
1998 | * This should not be called to advance the header if we are | |
1999 | * at the tail of the buffer. | |
2000 | */ | |
3e89c7bb | 2001 | if (RB_WARN_ON(cpu_buffer, |
f536aafc | 2002 | (iter->head_page == cpu_buffer->commit_page) && |
3e89c7bb SR |
2003 | (iter->head + length > rb_commit_index(cpu_buffer)))) |
2004 | return; | |
7a8e76a3 SR |
2005 | |
2006 | rb_update_iter_read_stamp(iter, event); | |
2007 | ||
2008 | iter->head += length; | |
2009 | ||
2010 | /* check for end of page padding */ | |
bf41a158 SR |
2011 | if ((iter->head >= rb_page_size(iter->head_page)) && |
2012 | (iter->head_page != cpu_buffer->commit_page)) | |
7a8e76a3 SR |
2013 | rb_advance_iter(iter); |
2014 | } | |
2015 | ||
f83c9d0f SR |
2016 | static struct ring_buffer_event * |
2017 | rb_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) | |
7a8e76a3 SR |
2018 | { |
2019 | struct ring_buffer_per_cpu *cpu_buffer; | |
2020 | struct ring_buffer_event *event; | |
d769041f | 2021 | struct buffer_page *reader; |
818e3dd3 | 2022 | int nr_loops = 0; |
7a8e76a3 | 2023 | |
7a8e76a3 SR |
2024 | cpu_buffer = buffer->buffers[cpu]; |
2025 | ||
2026 | again: | |
818e3dd3 SR |
2027 | /* |
2028 | * We repeat when a timestamp is encountered. It is possible | |
2029 | * to get multiple timestamps from an interrupt entering just | |
2030 | * as one timestamp is about to be written. The max times | |
2031 | * that this can happen is the number of nested interrupts we | |
2032 | * can have. Nesting 10 deep of interrupts is clearly | |
2033 | * an anomaly. | |
2034 | */ | |
3e89c7bb | 2035 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 10)) |
818e3dd3 | 2036 | return NULL; |
818e3dd3 | 2037 | |
d769041f SR |
2038 | reader = rb_get_reader_page(cpu_buffer); |
2039 | if (!reader) | |
7a8e76a3 SR |
2040 | return NULL; |
2041 | ||
d769041f | 2042 | event = rb_reader_event(cpu_buffer); |
7a8e76a3 SR |
2043 | |
2044 | switch (event->type) { | |
2045 | case RINGBUF_TYPE_PADDING: | |
bf41a158 | 2046 | RB_WARN_ON(cpu_buffer, 1); |
d769041f SR |
2047 | rb_advance_reader(cpu_buffer); |
2048 | return NULL; | |
7a8e76a3 SR |
2049 | |
2050 | case RINGBUF_TYPE_TIME_EXTEND: | |
2051 | /* Internal data, OK to advance */ | |
d769041f | 2052 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
2053 | goto again; |
2054 | ||
2055 | case RINGBUF_TYPE_TIME_STAMP: | |
2056 | /* FIXME: not implemented */ | |
d769041f | 2057 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
2058 | goto again; |
2059 | ||
2060 | case RINGBUF_TYPE_DATA: | |
2061 | if (ts) { | |
2062 | *ts = cpu_buffer->read_stamp + event->time_delta; | |
37886f6a SR |
2063 | ring_buffer_normalize_time_stamp(buffer, |
2064 | cpu_buffer->cpu, ts); | |
7a8e76a3 SR |
2065 | } |
2066 | return event; | |
2067 | ||
2068 | default: | |
2069 | BUG(); | |
2070 | } | |
2071 | ||
2072 | return NULL; | |
2073 | } | |
c4f50183 | 2074 | EXPORT_SYMBOL_GPL(ring_buffer_peek); |
7a8e76a3 | 2075 | |
f83c9d0f SR |
2076 | static struct ring_buffer_event * |
2077 | rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) | |
7a8e76a3 SR |
2078 | { |
2079 | struct ring_buffer *buffer; | |
2080 | struct ring_buffer_per_cpu *cpu_buffer; | |
2081 | struct ring_buffer_event *event; | |
818e3dd3 | 2082 | int nr_loops = 0; |
7a8e76a3 SR |
2083 | |
2084 | if (ring_buffer_iter_empty(iter)) | |
2085 | return NULL; | |
2086 | ||
2087 | cpu_buffer = iter->cpu_buffer; | |
2088 | buffer = cpu_buffer->buffer; | |
2089 | ||
2090 | again: | |
818e3dd3 SR |
2091 | /* |
2092 | * We repeat when a timestamp is encountered. It is possible | |
2093 | * to get multiple timestamps from an interrupt entering just | |
2094 | * as one timestamp is about to be written. The max times | |
2095 | * that this can happen is the number of nested interrupts we | |
2096 | * can have. Nesting 10 deep of interrupts is clearly | |
2097 | * an anomaly. | |
2098 | */ | |
3e89c7bb | 2099 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 10)) |
818e3dd3 | 2100 | return NULL; |
818e3dd3 | 2101 | |
7a8e76a3 SR |
2102 | if (rb_per_cpu_empty(cpu_buffer)) |
2103 | return NULL; | |
2104 | ||
2105 | event = rb_iter_head_event(iter); | |
2106 | ||
2107 | switch (event->type) { | |
2108 | case RINGBUF_TYPE_PADDING: | |
d769041f | 2109 | rb_inc_iter(iter); |
7a8e76a3 SR |
2110 | goto again; |
2111 | ||
2112 | case RINGBUF_TYPE_TIME_EXTEND: | |
2113 | /* Internal data, OK to advance */ | |
2114 | rb_advance_iter(iter); | |
2115 | goto again; | |
2116 | ||
2117 | case RINGBUF_TYPE_TIME_STAMP: | |
2118 | /* FIXME: not implemented */ | |
2119 | rb_advance_iter(iter); | |
2120 | goto again; | |
2121 | ||
2122 | case RINGBUF_TYPE_DATA: | |
2123 | if (ts) { | |
2124 | *ts = iter->read_stamp + event->time_delta; | |
37886f6a SR |
2125 | ring_buffer_normalize_time_stamp(buffer, |
2126 | cpu_buffer->cpu, ts); | |
7a8e76a3 SR |
2127 | } |
2128 | return event; | |
2129 | ||
2130 | default: | |
2131 | BUG(); | |
2132 | } | |
2133 | ||
2134 | return NULL; | |
2135 | } | |
c4f50183 | 2136 | EXPORT_SYMBOL_GPL(ring_buffer_iter_peek); |
7a8e76a3 | 2137 | |
f83c9d0f SR |
2138 | /** |
2139 | * ring_buffer_peek - peek at the next event to be read | |
2140 | * @buffer: The ring buffer to read | |
2141 | * @cpu: The cpu to peak at | |
2142 | * @ts: The timestamp counter of this event. | |
2143 | * | |
2144 | * This will return the event that will be read next, but does | |
2145 | * not consume the data. | |
2146 | */ | |
2147 | struct ring_buffer_event * | |
2148 | ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts) | |
2149 | { | |
2150 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
8aabee57 | 2151 | struct ring_buffer_event *event; |
f83c9d0f SR |
2152 | unsigned long flags; |
2153 | ||
554f786e | 2154 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 2155 | return NULL; |
554f786e | 2156 | |
f83c9d0f SR |
2157 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
2158 | event = rb_buffer_peek(buffer, cpu, ts); | |
2159 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
2160 | ||
2161 | return event; | |
2162 | } | |
2163 | ||
2164 | /** | |
2165 | * ring_buffer_iter_peek - peek at the next event to be read | |
2166 | * @iter: The ring buffer iterator | |
2167 | * @ts: The timestamp counter of this event. | |
2168 | * | |
2169 | * This will return the event that will be read next, but does | |
2170 | * not increment the iterator. | |
2171 | */ | |
2172 | struct ring_buffer_event * | |
2173 | ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) | |
2174 | { | |
2175 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
2176 | struct ring_buffer_event *event; | |
2177 | unsigned long flags; | |
2178 | ||
2179 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
2180 | event = rb_iter_peek(iter, ts); | |
2181 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
2182 | ||
2183 | return event; | |
2184 | } | |
2185 | ||
7a8e76a3 SR |
2186 | /** |
2187 | * ring_buffer_consume - return an event and consume it | |
2188 | * @buffer: The ring buffer to get the next event from | |
2189 | * | |
2190 | * Returns the next event in the ring buffer, and that event is consumed. | |
2191 | * Meaning, that sequential reads will keep returning a different event, | |
2192 | * and eventually empty the ring buffer if the producer is slower. | |
2193 | */ | |
2194 | struct ring_buffer_event * | |
2195 | ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts) | |
2196 | { | |
554f786e SR |
2197 | struct ring_buffer_per_cpu *cpu_buffer; |
2198 | struct ring_buffer_event *event = NULL; | |
f83c9d0f | 2199 | unsigned long flags; |
7a8e76a3 | 2200 | |
554f786e SR |
2201 | /* might be called in atomic */ |
2202 | preempt_disable(); | |
2203 | ||
9e01c1b7 | 2204 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
554f786e | 2205 | goto out; |
7a8e76a3 | 2206 | |
554f786e | 2207 | cpu_buffer = buffer->buffers[cpu]; |
f83c9d0f SR |
2208 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
2209 | ||
2210 | event = rb_buffer_peek(buffer, cpu, ts); | |
7a8e76a3 | 2211 | if (!event) |
554f786e | 2212 | goto out_unlock; |
7a8e76a3 | 2213 | |
d769041f | 2214 | rb_advance_reader(cpu_buffer); |
7a8e76a3 | 2215 | |
554f786e | 2216 | out_unlock: |
f83c9d0f SR |
2217 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
2218 | ||
554f786e SR |
2219 | out: |
2220 | preempt_enable(); | |
2221 | ||
7a8e76a3 SR |
2222 | return event; |
2223 | } | |
c4f50183 | 2224 | EXPORT_SYMBOL_GPL(ring_buffer_consume); |
7a8e76a3 SR |
2225 | |
2226 | /** | |
2227 | * ring_buffer_read_start - start a non consuming read of the buffer | |
2228 | * @buffer: The ring buffer to read from | |
2229 | * @cpu: The cpu buffer to iterate over | |
2230 | * | |
2231 | * This starts up an iteration through the buffer. It also disables | |
2232 | * the recording to the buffer until the reading is finished. | |
2233 | * This prevents the reading from being corrupted. This is not | |
2234 | * a consuming read, so a producer is not expected. | |
2235 | * | |
2236 | * Must be paired with ring_buffer_finish. | |
2237 | */ | |
2238 | struct ring_buffer_iter * | |
2239 | ring_buffer_read_start(struct ring_buffer *buffer, int cpu) | |
2240 | { | |
2241 | struct ring_buffer_per_cpu *cpu_buffer; | |
8aabee57 | 2242 | struct ring_buffer_iter *iter; |
d769041f | 2243 | unsigned long flags; |
7a8e76a3 | 2244 | |
9e01c1b7 | 2245 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 2246 | return NULL; |
7a8e76a3 SR |
2247 | |
2248 | iter = kmalloc(sizeof(*iter), GFP_KERNEL); | |
2249 | if (!iter) | |
8aabee57 | 2250 | return NULL; |
7a8e76a3 SR |
2251 | |
2252 | cpu_buffer = buffer->buffers[cpu]; | |
2253 | ||
2254 | iter->cpu_buffer = cpu_buffer; | |
2255 | ||
2256 | atomic_inc(&cpu_buffer->record_disabled); | |
2257 | synchronize_sched(); | |
2258 | ||
f83c9d0f | 2259 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
3e03fb7f | 2260 | __raw_spin_lock(&cpu_buffer->lock); |
642edba5 | 2261 | rb_iter_reset(iter); |
3e03fb7f | 2262 | __raw_spin_unlock(&cpu_buffer->lock); |
f83c9d0f | 2263 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
7a8e76a3 SR |
2264 | |
2265 | return iter; | |
2266 | } | |
c4f50183 | 2267 | EXPORT_SYMBOL_GPL(ring_buffer_read_start); |
7a8e76a3 SR |
2268 | |
2269 | /** | |
2270 | * ring_buffer_finish - finish reading the iterator of the buffer | |
2271 | * @iter: The iterator retrieved by ring_buffer_start | |
2272 | * | |
2273 | * This re-enables the recording to the buffer, and frees the | |
2274 | * iterator. | |
2275 | */ | |
2276 | void | |
2277 | ring_buffer_read_finish(struct ring_buffer_iter *iter) | |
2278 | { | |
2279 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
2280 | ||
2281 | atomic_dec(&cpu_buffer->record_disabled); | |
2282 | kfree(iter); | |
2283 | } | |
c4f50183 | 2284 | EXPORT_SYMBOL_GPL(ring_buffer_read_finish); |
7a8e76a3 SR |
2285 | |
2286 | /** | |
2287 | * ring_buffer_read - read the next item in the ring buffer by the iterator | |
2288 | * @iter: The ring buffer iterator | |
2289 | * @ts: The time stamp of the event read. | |
2290 | * | |
2291 | * This reads the next event in the ring buffer and increments the iterator. | |
2292 | */ | |
2293 | struct ring_buffer_event * | |
2294 | ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) | |
2295 | { | |
2296 | struct ring_buffer_event *event; | |
f83c9d0f SR |
2297 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
2298 | unsigned long flags; | |
7a8e76a3 | 2299 | |
f83c9d0f SR |
2300 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
2301 | event = rb_iter_peek(iter, ts); | |
7a8e76a3 | 2302 | if (!event) |
f83c9d0f | 2303 | goto out; |
7a8e76a3 SR |
2304 | |
2305 | rb_advance_iter(iter); | |
f83c9d0f SR |
2306 | out: |
2307 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
7a8e76a3 SR |
2308 | |
2309 | return event; | |
2310 | } | |
c4f50183 | 2311 | EXPORT_SYMBOL_GPL(ring_buffer_read); |
7a8e76a3 SR |
2312 | |
2313 | /** | |
2314 | * ring_buffer_size - return the size of the ring buffer (in bytes) | |
2315 | * @buffer: The ring buffer. | |
2316 | */ | |
2317 | unsigned long ring_buffer_size(struct ring_buffer *buffer) | |
2318 | { | |
2319 | return BUF_PAGE_SIZE * buffer->pages; | |
2320 | } | |
c4f50183 | 2321 | EXPORT_SYMBOL_GPL(ring_buffer_size); |
7a8e76a3 SR |
2322 | |
2323 | static void | |
2324 | rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) | |
2325 | { | |
2326 | cpu_buffer->head_page | |
2327 | = list_entry(cpu_buffer->pages.next, struct buffer_page, list); | |
bf41a158 | 2328 | local_set(&cpu_buffer->head_page->write, 0); |
abc9b56d | 2329 | local_set(&cpu_buffer->head_page->page->commit, 0); |
d769041f | 2330 | |
6f807acd | 2331 | cpu_buffer->head_page->read = 0; |
bf41a158 SR |
2332 | |
2333 | cpu_buffer->tail_page = cpu_buffer->head_page; | |
2334 | cpu_buffer->commit_page = cpu_buffer->head_page; | |
2335 | ||
2336 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); | |
2337 | local_set(&cpu_buffer->reader_page->write, 0); | |
abc9b56d | 2338 | local_set(&cpu_buffer->reader_page->page->commit, 0); |
6f807acd | 2339 | cpu_buffer->reader_page->read = 0; |
7a8e76a3 | 2340 | |
7a8e76a3 SR |
2341 | cpu_buffer->overrun = 0; |
2342 | cpu_buffer->entries = 0; | |
69507c06 SR |
2343 | |
2344 | cpu_buffer->write_stamp = 0; | |
2345 | cpu_buffer->read_stamp = 0; | |
7a8e76a3 SR |
2346 | } |
2347 | ||
2348 | /** | |
2349 | * ring_buffer_reset_cpu - reset a ring buffer per CPU buffer | |
2350 | * @buffer: The ring buffer to reset a per cpu buffer of | |
2351 | * @cpu: The CPU buffer to be reset | |
2352 | */ | |
2353 | void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) | |
2354 | { | |
2355 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
2356 | unsigned long flags; | |
2357 | ||
9e01c1b7 | 2358 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 2359 | return; |
7a8e76a3 | 2360 | |
f83c9d0f SR |
2361 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
2362 | ||
3e03fb7f | 2363 | __raw_spin_lock(&cpu_buffer->lock); |
7a8e76a3 SR |
2364 | |
2365 | rb_reset_cpu(cpu_buffer); | |
2366 | ||
3e03fb7f | 2367 | __raw_spin_unlock(&cpu_buffer->lock); |
f83c9d0f SR |
2368 | |
2369 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
7a8e76a3 | 2370 | } |
c4f50183 | 2371 | EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); |
7a8e76a3 SR |
2372 | |
2373 | /** | |
2374 | * ring_buffer_reset - reset a ring buffer | |
2375 | * @buffer: The ring buffer to reset all cpu buffers | |
2376 | */ | |
2377 | void ring_buffer_reset(struct ring_buffer *buffer) | |
2378 | { | |
7a8e76a3 SR |
2379 | int cpu; |
2380 | ||
7a8e76a3 | 2381 | for_each_buffer_cpu(buffer, cpu) |
d769041f | 2382 | ring_buffer_reset_cpu(buffer, cpu); |
7a8e76a3 | 2383 | } |
c4f50183 | 2384 | EXPORT_SYMBOL_GPL(ring_buffer_reset); |
7a8e76a3 SR |
2385 | |
2386 | /** | |
2387 | * rind_buffer_empty - is the ring buffer empty? | |
2388 | * @buffer: The ring buffer to test | |
2389 | */ | |
2390 | int ring_buffer_empty(struct ring_buffer *buffer) | |
2391 | { | |
2392 | struct ring_buffer_per_cpu *cpu_buffer; | |
2393 | int cpu; | |
2394 | ||
2395 | /* yes this is racy, but if you don't like the race, lock the buffer */ | |
2396 | for_each_buffer_cpu(buffer, cpu) { | |
2397 | cpu_buffer = buffer->buffers[cpu]; | |
2398 | if (!rb_per_cpu_empty(cpu_buffer)) | |
2399 | return 0; | |
2400 | } | |
554f786e | 2401 | |
7a8e76a3 SR |
2402 | return 1; |
2403 | } | |
c4f50183 | 2404 | EXPORT_SYMBOL_GPL(ring_buffer_empty); |
7a8e76a3 SR |
2405 | |
2406 | /** | |
2407 | * ring_buffer_empty_cpu - is a cpu buffer of a ring buffer empty? | |
2408 | * @buffer: The ring buffer | |
2409 | * @cpu: The CPU buffer to test | |
2410 | */ | |
2411 | int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) | |
2412 | { | |
2413 | struct ring_buffer_per_cpu *cpu_buffer; | |
8aabee57 | 2414 | int ret; |
7a8e76a3 | 2415 | |
9e01c1b7 | 2416 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 2417 | return 1; |
7a8e76a3 SR |
2418 | |
2419 | cpu_buffer = buffer->buffers[cpu]; | |
554f786e SR |
2420 | ret = rb_per_cpu_empty(cpu_buffer); |
2421 | ||
554f786e SR |
2422 | |
2423 | return ret; | |
7a8e76a3 | 2424 | } |
c4f50183 | 2425 | EXPORT_SYMBOL_GPL(ring_buffer_empty_cpu); |
7a8e76a3 SR |
2426 | |
2427 | /** | |
2428 | * ring_buffer_swap_cpu - swap a CPU buffer between two ring buffers | |
2429 | * @buffer_a: One buffer to swap with | |
2430 | * @buffer_b: The other buffer to swap with | |
2431 | * | |
2432 | * This function is useful for tracers that want to take a "snapshot" | |
2433 | * of a CPU buffer and has another back up buffer lying around. | |
2434 | * it is expected that the tracer handles the cpu buffer not being | |
2435 | * used at the moment. | |
2436 | */ | |
2437 | int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, | |
2438 | struct ring_buffer *buffer_b, int cpu) | |
2439 | { | |
2440 | struct ring_buffer_per_cpu *cpu_buffer_a; | |
2441 | struct ring_buffer_per_cpu *cpu_buffer_b; | |
554f786e SR |
2442 | int ret = -EINVAL; |
2443 | ||
9e01c1b7 RR |
2444 | if (!cpumask_test_cpu(cpu, buffer_a->cpumask) || |
2445 | !cpumask_test_cpu(cpu, buffer_b->cpumask)) | |
554f786e | 2446 | goto out; |
7a8e76a3 SR |
2447 | |
2448 | /* At least make sure the two buffers are somewhat the same */ | |
6d102bc6 | 2449 | if (buffer_a->pages != buffer_b->pages) |
554f786e SR |
2450 | goto out; |
2451 | ||
2452 | ret = -EAGAIN; | |
7a8e76a3 | 2453 | |
97b17efe | 2454 | if (ring_buffer_flags != RB_BUFFERS_ON) |
554f786e | 2455 | goto out; |
97b17efe SR |
2456 | |
2457 | if (atomic_read(&buffer_a->record_disabled)) | |
554f786e | 2458 | goto out; |
97b17efe SR |
2459 | |
2460 | if (atomic_read(&buffer_b->record_disabled)) | |
554f786e | 2461 | goto out; |
97b17efe | 2462 | |
7a8e76a3 SR |
2463 | cpu_buffer_a = buffer_a->buffers[cpu]; |
2464 | cpu_buffer_b = buffer_b->buffers[cpu]; | |
2465 | ||
97b17efe | 2466 | if (atomic_read(&cpu_buffer_a->record_disabled)) |
554f786e | 2467 | goto out; |
97b17efe SR |
2468 | |
2469 | if (atomic_read(&cpu_buffer_b->record_disabled)) | |
554f786e | 2470 | goto out; |
97b17efe | 2471 | |
7a8e76a3 SR |
2472 | /* |
2473 | * We can't do a synchronize_sched here because this | |
2474 | * function can be called in atomic context. | |
2475 | * Normally this will be called from the same CPU as cpu. | |
2476 | * If not it's up to the caller to protect this. | |
2477 | */ | |
2478 | atomic_inc(&cpu_buffer_a->record_disabled); | |
2479 | atomic_inc(&cpu_buffer_b->record_disabled); | |
2480 | ||
2481 | buffer_a->buffers[cpu] = cpu_buffer_b; | |
2482 | buffer_b->buffers[cpu] = cpu_buffer_a; | |
2483 | ||
2484 | cpu_buffer_b->buffer = buffer_a; | |
2485 | cpu_buffer_a->buffer = buffer_b; | |
2486 | ||
2487 | atomic_dec(&cpu_buffer_a->record_disabled); | |
2488 | atomic_dec(&cpu_buffer_b->record_disabled); | |
2489 | ||
554f786e SR |
2490 | ret = 0; |
2491 | out: | |
554f786e | 2492 | return ret; |
7a8e76a3 | 2493 | } |
c4f50183 | 2494 | EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu); |
7a8e76a3 | 2495 | |
8789a9e7 | 2496 | static void rb_remove_entries(struct ring_buffer_per_cpu *cpu_buffer, |
667d2412 LJ |
2497 | struct buffer_data_page *bpage, |
2498 | unsigned int offset) | |
8789a9e7 SR |
2499 | { |
2500 | struct ring_buffer_event *event; | |
2501 | unsigned long head; | |
2502 | ||
2503 | __raw_spin_lock(&cpu_buffer->lock); | |
667d2412 | 2504 | for (head = offset; head < local_read(&bpage->commit); |
8789a9e7 SR |
2505 | head += rb_event_length(event)) { |
2506 | ||
044fa782 | 2507 | event = __rb_data_page_index(bpage, head); |
8789a9e7 SR |
2508 | if (RB_WARN_ON(cpu_buffer, rb_null_event(event))) |
2509 | return; | |
2510 | /* Only count data entries */ | |
2511 | if (event->type != RINGBUF_TYPE_DATA) | |
2512 | continue; | |
2513 | cpu_buffer->entries--; | |
2514 | } | |
2515 | __raw_spin_unlock(&cpu_buffer->lock); | |
2516 | } | |
2517 | ||
2518 | /** | |
2519 | * ring_buffer_alloc_read_page - allocate a page to read from buffer | |
2520 | * @buffer: the buffer to allocate for. | |
2521 | * | |
2522 | * This function is used in conjunction with ring_buffer_read_page. | |
2523 | * When reading a full page from the ring buffer, these functions | |
2524 | * can be used to speed up the process. The calling function should | |
2525 | * allocate a few pages first with this function. Then when it | |
2526 | * needs to get pages from the ring buffer, it passes the result | |
2527 | * of this function into ring_buffer_read_page, which will swap | |
2528 | * the page that was allocated, with the read page of the buffer. | |
2529 | * | |
2530 | * Returns: | |
2531 | * The page allocated, or NULL on error. | |
2532 | */ | |
2533 | void *ring_buffer_alloc_read_page(struct ring_buffer *buffer) | |
2534 | { | |
044fa782 | 2535 | struct buffer_data_page *bpage; |
ef7a4a16 | 2536 | unsigned long addr; |
8789a9e7 SR |
2537 | |
2538 | addr = __get_free_page(GFP_KERNEL); | |
2539 | if (!addr) | |
2540 | return NULL; | |
2541 | ||
044fa782 | 2542 | bpage = (void *)addr; |
8789a9e7 | 2543 | |
ef7a4a16 SR |
2544 | rb_init_page(bpage); |
2545 | ||
044fa782 | 2546 | return bpage; |
8789a9e7 SR |
2547 | } |
2548 | ||
2549 | /** | |
2550 | * ring_buffer_free_read_page - free an allocated read page | |
2551 | * @buffer: the buffer the page was allocate for | |
2552 | * @data: the page to free | |
2553 | * | |
2554 | * Free a page allocated from ring_buffer_alloc_read_page. | |
2555 | */ | |
2556 | void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data) | |
2557 | { | |
2558 | free_page((unsigned long)data); | |
2559 | } | |
2560 | ||
2561 | /** | |
2562 | * ring_buffer_read_page - extract a page from the ring buffer | |
2563 | * @buffer: buffer to extract from | |
2564 | * @data_page: the page to use allocated from ring_buffer_alloc_read_page | |
ef7a4a16 | 2565 | * @len: amount to extract |
8789a9e7 SR |
2566 | * @cpu: the cpu of the buffer to extract |
2567 | * @full: should the extraction only happen when the page is full. | |
2568 | * | |
2569 | * This function will pull out a page from the ring buffer and consume it. | |
2570 | * @data_page must be the address of the variable that was returned | |
2571 | * from ring_buffer_alloc_read_page. This is because the page might be used | |
2572 | * to swap with a page in the ring buffer. | |
2573 | * | |
2574 | * for example: | |
b85fa01e | 2575 | * rpage = ring_buffer_alloc_read_page(buffer); |
8789a9e7 SR |
2576 | * if (!rpage) |
2577 | * return error; | |
ef7a4a16 | 2578 | * ret = ring_buffer_read_page(buffer, &rpage, len, cpu, 0); |
667d2412 LJ |
2579 | * if (ret >= 0) |
2580 | * process_page(rpage, ret); | |
8789a9e7 SR |
2581 | * |
2582 | * When @full is set, the function will not return true unless | |
2583 | * the writer is off the reader page. | |
2584 | * | |
2585 | * Note: it is up to the calling functions to handle sleeps and wakeups. | |
2586 | * The ring buffer can be used anywhere in the kernel and can not | |
2587 | * blindly call wake_up. The layer that uses the ring buffer must be | |
2588 | * responsible for that. | |
2589 | * | |
2590 | * Returns: | |
667d2412 LJ |
2591 | * >=0 if data has been transferred, returns the offset of consumed data. |
2592 | * <0 if no data has been transferred. | |
8789a9e7 SR |
2593 | */ |
2594 | int ring_buffer_read_page(struct ring_buffer *buffer, | |
ef7a4a16 | 2595 | void **data_page, size_t len, int cpu, int full) |
8789a9e7 SR |
2596 | { |
2597 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
2598 | struct ring_buffer_event *event; | |
044fa782 | 2599 | struct buffer_data_page *bpage; |
ef7a4a16 | 2600 | struct buffer_page *reader; |
8789a9e7 | 2601 | unsigned long flags; |
ef7a4a16 | 2602 | unsigned int commit; |
667d2412 | 2603 | unsigned int read; |
4f3640f8 | 2604 | u64 save_timestamp; |
667d2412 | 2605 | int ret = -1; |
8789a9e7 | 2606 | |
554f786e SR |
2607 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
2608 | goto out; | |
2609 | ||
474d32b6 SR |
2610 | /* |
2611 | * If len is not big enough to hold the page header, then | |
2612 | * we can not copy anything. | |
2613 | */ | |
2614 | if (len <= BUF_PAGE_HDR_SIZE) | |
554f786e | 2615 | goto out; |
474d32b6 SR |
2616 | |
2617 | len -= BUF_PAGE_HDR_SIZE; | |
2618 | ||
8789a9e7 | 2619 | if (!data_page) |
554f786e | 2620 | goto out; |
8789a9e7 | 2621 | |
044fa782 SR |
2622 | bpage = *data_page; |
2623 | if (!bpage) | |
554f786e | 2624 | goto out; |
8789a9e7 SR |
2625 | |
2626 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
2627 | ||
ef7a4a16 SR |
2628 | reader = rb_get_reader_page(cpu_buffer); |
2629 | if (!reader) | |
554f786e | 2630 | goto out_unlock; |
8789a9e7 | 2631 | |
ef7a4a16 SR |
2632 | event = rb_reader_event(cpu_buffer); |
2633 | ||
2634 | read = reader->read; | |
2635 | commit = rb_page_commit(reader); | |
667d2412 | 2636 | |
8789a9e7 | 2637 | /* |
474d32b6 SR |
2638 | * If this page has been partially read or |
2639 | * if len is not big enough to read the rest of the page or | |
2640 | * a writer is still on the page, then | |
2641 | * we must copy the data from the page to the buffer. | |
2642 | * Otherwise, we can simply swap the page with the one passed in. | |
8789a9e7 | 2643 | */ |
474d32b6 | 2644 | if (read || (len < (commit - read)) || |
ef7a4a16 | 2645 | cpu_buffer->reader_page == cpu_buffer->commit_page) { |
667d2412 | 2646 | struct buffer_data_page *rpage = cpu_buffer->reader_page->page; |
474d32b6 SR |
2647 | unsigned int rpos = read; |
2648 | unsigned int pos = 0; | |
ef7a4a16 | 2649 | unsigned int size; |
8789a9e7 SR |
2650 | |
2651 | if (full) | |
554f786e | 2652 | goto out_unlock; |
8789a9e7 | 2653 | |
ef7a4a16 SR |
2654 | if (len > (commit - read)) |
2655 | len = (commit - read); | |
2656 | ||
2657 | size = rb_event_length(event); | |
2658 | ||
2659 | if (len < size) | |
554f786e | 2660 | goto out_unlock; |
ef7a4a16 | 2661 | |
4f3640f8 SR |
2662 | /* save the current timestamp, since the user will need it */ |
2663 | save_timestamp = cpu_buffer->read_stamp; | |
2664 | ||
ef7a4a16 SR |
2665 | /* Need to copy one event at a time */ |
2666 | do { | |
474d32b6 | 2667 | memcpy(bpage->data + pos, rpage->data + rpos, size); |
ef7a4a16 SR |
2668 | |
2669 | len -= size; | |
2670 | ||
2671 | rb_advance_reader(cpu_buffer); | |
474d32b6 SR |
2672 | rpos = reader->read; |
2673 | pos += size; | |
ef7a4a16 SR |
2674 | |
2675 | event = rb_reader_event(cpu_buffer); | |
2676 | size = rb_event_length(event); | |
2677 | } while (len > size); | |
667d2412 LJ |
2678 | |
2679 | /* update bpage */ | |
ef7a4a16 | 2680 | local_set(&bpage->commit, pos); |
4f3640f8 | 2681 | bpage->time_stamp = save_timestamp; |
ef7a4a16 | 2682 | |
474d32b6 SR |
2683 | /* we copied everything to the beginning */ |
2684 | read = 0; | |
8789a9e7 SR |
2685 | } else { |
2686 | /* swap the pages */ | |
044fa782 | 2687 | rb_init_page(bpage); |
ef7a4a16 SR |
2688 | bpage = reader->page; |
2689 | reader->page = *data_page; | |
2690 | local_set(&reader->write, 0); | |
2691 | reader->read = 0; | |
044fa782 | 2692 | *data_page = bpage; |
ef7a4a16 SR |
2693 | |
2694 | /* update the entry counter */ | |
2695 | rb_remove_entries(cpu_buffer, bpage, read); | |
8789a9e7 | 2696 | } |
667d2412 | 2697 | ret = read; |
8789a9e7 | 2698 | |
554f786e | 2699 | out_unlock: |
8789a9e7 SR |
2700 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
2701 | ||
554f786e | 2702 | out: |
8789a9e7 SR |
2703 | return ret; |
2704 | } | |
2705 | ||
a3583244 SR |
2706 | static ssize_t |
2707 | rb_simple_read(struct file *filp, char __user *ubuf, | |
2708 | size_t cnt, loff_t *ppos) | |
2709 | { | |
5e39841c | 2710 | unsigned long *p = filp->private_data; |
a3583244 SR |
2711 | char buf[64]; |
2712 | int r; | |
2713 | ||
033601a3 SR |
2714 | if (test_bit(RB_BUFFERS_DISABLED_BIT, p)) |
2715 | r = sprintf(buf, "permanently disabled\n"); | |
2716 | else | |
2717 | r = sprintf(buf, "%d\n", test_bit(RB_BUFFERS_ON_BIT, p)); | |
a3583244 SR |
2718 | |
2719 | return simple_read_from_buffer(ubuf, cnt, ppos, buf, r); | |
2720 | } | |
2721 | ||
2722 | static ssize_t | |
2723 | rb_simple_write(struct file *filp, const char __user *ubuf, | |
2724 | size_t cnt, loff_t *ppos) | |
2725 | { | |
5e39841c | 2726 | unsigned long *p = filp->private_data; |
a3583244 | 2727 | char buf[64]; |
5e39841c | 2728 | unsigned long val; |
a3583244 SR |
2729 | int ret; |
2730 | ||
2731 | if (cnt >= sizeof(buf)) | |
2732 | return -EINVAL; | |
2733 | ||
2734 | if (copy_from_user(&buf, ubuf, cnt)) | |
2735 | return -EFAULT; | |
2736 | ||
2737 | buf[cnt] = 0; | |
2738 | ||
2739 | ret = strict_strtoul(buf, 10, &val); | |
2740 | if (ret < 0) | |
2741 | return ret; | |
2742 | ||
033601a3 SR |
2743 | if (val) |
2744 | set_bit(RB_BUFFERS_ON_BIT, p); | |
2745 | else | |
2746 | clear_bit(RB_BUFFERS_ON_BIT, p); | |
a3583244 SR |
2747 | |
2748 | (*ppos)++; | |
2749 | ||
2750 | return cnt; | |
2751 | } | |
2752 | ||
5e2336a0 | 2753 | static const struct file_operations rb_simple_fops = { |
a3583244 SR |
2754 | .open = tracing_open_generic, |
2755 | .read = rb_simple_read, | |
2756 | .write = rb_simple_write, | |
2757 | }; | |
2758 | ||
2759 | ||
2760 | static __init int rb_init_debugfs(void) | |
2761 | { | |
2762 | struct dentry *d_tracer; | |
2763 | struct dentry *entry; | |
2764 | ||
2765 | d_tracer = tracing_init_dentry(); | |
2766 | ||
2767 | entry = debugfs_create_file("tracing_on", 0644, d_tracer, | |
033601a3 | 2768 | &ring_buffer_flags, &rb_simple_fops); |
a3583244 SR |
2769 | if (!entry) |
2770 | pr_warning("Could not create debugfs 'tracing_on' entry\n"); | |
2771 | ||
2772 | return 0; | |
2773 | } | |
2774 | ||
2775 | fs_initcall(rb_init_debugfs); | |
554f786e | 2776 | |
59222efe | 2777 | #ifdef CONFIG_HOTPLUG_CPU |
554f786e SR |
2778 | static int __cpuinit rb_cpu_notify(struct notifier_block *self, |
2779 | unsigned long action, void *hcpu) | |
2780 | { | |
2781 | struct ring_buffer *buffer = | |
2782 | container_of(self, struct ring_buffer, cpu_notify); | |
2783 | long cpu = (long)hcpu; | |
2784 | ||
2785 | switch (action) { | |
2786 | case CPU_UP_PREPARE: | |
2787 | case CPU_UP_PREPARE_FROZEN: | |
2788 | if (cpu_isset(cpu, *buffer->cpumask)) | |
2789 | return NOTIFY_OK; | |
2790 | ||
2791 | buffer->buffers[cpu] = | |
2792 | rb_allocate_cpu_buffer(buffer, cpu); | |
2793 | if (!buffer->buffers[cpu]) { | |
2794 | WARN(1, "failed to allocate ring buffer on CPU %ld\n", | |
2795 | cpu); | |
2796 | return NOTIFY_OK; | |
2797 | } | |
2798 | smp_wmb(); | |
2799 | cpu_set(cpu, *buffer->cpumask); | |
2800 | break; | |
2801 | case CPU_DOWN_PREPARE: | |
2802 | case CPU_DOWN_PREPARE_FROZEN: | |
2803 | /* | |
2804 | * Do nothing. | |
2805 | * If we were to free the buffer, then the user would | |
2806 | * lose any trace that was in the buffer. | |
2807 | */ | |
2808 | break; | |
2809 | default: | |
2810 | break; | |
2811 | } | |
2812 | return NOTIFY_OK; | |
2813 | } | |
2814 | #endif |