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Commit | Line | Data |
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7a8e76a3 SR |
1 | /* |
2 | * Generic ring buffer | |
3 | * | |
4 | * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com> | |
5 | */ | |
6 | #include <linux/ring_buffer.h> | |
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> |
1744a21d | 13 | #include <linux/kmemcheck.h> |
7a8e76a3 SR |
14 | #include <linux/module.h> |
15 | #include <linux/percpu.h> | |
16 | #include <linux/mutex.h> | |
5a0e3ad6 | 17 | #include <linux/slab.h> |
7a8e76a3 SR |
18 | #include <linux/init.h> |
19 | #include <linux/hash.h> | |
20 | #include <linux/list.h> | |
554f786e | 21 | #include <linux/cpu.h> |
7a8e76a3 SR |
22 | #include <linux/fs.h> |
23 | ||
79615760 | 24 | #include <asm/local.h> |
182e9f5f SR |
25 | #include "trace.h" |
26 | ||
d1b182a8 SR |
27 | /* |
28 | * The ring buffer header is special. We must manually up keep it. | |
29 | */ | |
30 | int ring_buffer_print_entry_header(struct trace_seq *s) | |
31 | { | |
32 | int ret; | |
33 | ||
334d4169 LJ |
34 | ret = trace_seq_printf(s, "# compressed entry header\n"); |
35 | ret = trace_seq_printf(s, "\ttype_len : 5 bits\n"); | |
d1b182a8 SR |
36 | ret = trace_seq_printf(s, "\ttime_delta : 27 bits\n"); |
37 | ret = trace_seq_printf(s, "\tarray : 32 bits\n"); | |
38 | ret = trace_seq_printf(s, "\n"); | |
39 | ret = trace_seq_printf(s, "\tpadding : type == %d\n", | |
40 | RINGBUF_TYPE_PADDING); | |
41 | ret = trace_seq_printf(s, "\ttime_extend : type == %d\n", | |
42 | RINGBUF_TYPE_TIME_EXTEND); | |
334d4169 LJ |
43 | ret = trace_seq_printf(s, "\tdata max type_len == %d\n", |
44 | RINGBUF_TYPE_DATA_TYPE_LEN_MAX); | |
d1b182a8 SR |
45 | |
46 | return ret; | |
47 | } | |
48 | ||
5cc98548 SR |
49 | /* |
50 | * The ring buffer is made up of a list of pages. A separate list of pages is | |
51 | * allocated for each CPU. A writer may only write to a buffer that is | |
52 | * associated with the CPU it is currently executing on. A reader may read | |
53 | * from any per cpu buffer. | |
54 | * | |
55 | * The reader is special. For each per cpu buffer, the reader has its own | |
56 | * reader page. When a reader has read the entire reader page, this reader | |
57 | * page is swapped with another page in the ring buffer. | |
58 | * | |
59 | * Now, as long as the writer is off the reader page, the reader can do what | |
60 | * ever it wants with that page. The writer will never write to that page | |
61 | * again (as long as it is out of the ring buffer). | |
62 | * | |
63 | * Here's some silly ASCII art. | |
64 | * | |
65 | * +------+ | |
66 | * |reader| RING BUFFER | |
67 | * |page | | |
68 | * +------+ +---+ +---+ +---+ | |
69 | * | |-->| |-->| | | |
70 | * +---+ +---+ +---+ | |
71 | * ^ | | |
72 | * | | | |
73 | * +---------------+ | |
74 | * | |
75 | * | |
76 | * +------+ | |
77 | * |reader| RING BUFFER | |
78 | * |page |------------------v | |
79 | * +------+ +---+ +---+ +---+ | |
80 | * | |-->| |-->| | | |
81 | * +---+ +---+ +---+ | |
82 | * ^ | | |
83 | * | | | |
84 | * +---------------+ | |
85 | * | |
86 | * | |
87 | * +------+ | |
88 | * |reader| RING BUFFER | |
89 | * |page |------------------v | |
90 | * +------+ +---+ +---+ +---+ | |
91 | * ^ | |-->| |-->| | | |
92 | * | +---+ +---+ +---+ | |
93 | * | | | |
94 | * | | | |
95 | * +------------------------------+ | |
96 | * | |
97 | * | |
98 | * +------+ | |
99 | * |buffer| RING BUFFER | |
100 | * |page |------------------v | |
101 | * +------+ +---+ +---+ +---+ | |
102 | * ^ | | | |-->| | | |
103 | * | New +---+ +---+ +---+ | |
104 | * | Reader------^ | | |
105 | * | page | | |
106 | * +------------------------------+ | |
107 | * | |
108 | * | |
109 | * After we make this swap, the reader can hand this page off to the splice | |
110 | * code and be done with it. It can even allocate a new page if it needs to | |
111 | * and swap that into the ring buffer. | |
112 | * | |
113 | * We will be using cmpxchg soon to make all this lockless. | |
114 | * | |
115 | */ | |
116 | ||
033601a3 SR |
117 | /* |
118 | * A fast way to enable or disable all ring buffers is to | |
119 | * call tracing_on or tracing_off. Turning off the ring buffers | |
120 | * prevents all ring buffers from being recorded to. | |
121 | * Turning this switch on, makes it OK to write to the | |
122 | * ring buffer, if the ring buffer is enabled itself. | |
123 | * | |
124 | * There's three layers that must be on in order to write | |
125 | * to the ring buffer. | |
126 | * | |
127 | * 1) This global flag must be set. | |
128 | * 2) The ring buffer must be enabled for recording. | |
129 | * 3) The per cpu buffer must be enabled for recording. | |
130 | * | |
131 | * In case of an anomaly, this global flag has a bit set that | |
132 | * will permantly disable all ring buffers. | |
133 | */ | |
134 | ||
135 | /* | |
136 | * Global flag to disable all recording to ring buffers | |
137 | * This has two bits: ON, DISABLED | |
138 | * | |
139 | * ON DISABLED | |
140 | * ---- ---------- | |
141 | * 0 0 : ring buffers are off | |
142 | * 1 0 : ring buffers are on | |
143 | * X 1 : ring buffers are permanently disabled | |
144 | */ | |
145 | ||
146 | enum { | |
147 | RB_BUFFERS_ON_BIT = 0, | |
148 | RB_BUFFERS_DISABLED_BIT = 1, | |
149 | }; | |
150 | ||
151 | enum { | |
152 | RB_BUFFERS_ON = 1 << RB_BUFFERS_ON_BIT, | |
153 | RB_BUFFERS_DISABLED = 1 << RB_BUFFERS_DISABLED_BIT, | |
154 | }; | |
155 | ||
5e39841c | 156 | static unsigned long ring_buffer_flags __read_mostly = RB_BUFFERS_ON; |
a3583244 | 157 | |
474d32b6 SR |
158 | #define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data) |
159 | ||
a3583244 SR |
160 | /** |
161 | * tracing_on - enable all tracing buffers | |
162 | * | |
163 | * This function enables all tracing buffers that may have been | |
164 | * disabled with tracing_off. | |
165 | */ | |
166 | void tracing_on(void) | |
167 | { | |
033601a3 | 168 | set_bit(RB_BUFFERS_ON_BIT, &ring_buffer_flags); |
a3583244 | 169 | } |
c4f50183 | 170 | EXPORT_SYMBOL_GPL(tracing_on); |
a3583244 SR |
171 | |
172 | /** | |
173 | * tracing_off - turn off all tracing buffers | |
174 | * | |
175 | * This function stops all tracing buffers from recording data. | |
176 | * It does not disable any overhead the tracers themselves may | |
177 | * be causing. This function simply causes all recording to | |
178 | * the ring buffers to fail. | |
179 | */ | |
180 | void tracing_off(void) | |
181 | { | |
033601a3 SR |
182 | clear_bit(RB_BUFFERS_ON_BIT, &ring_buffer_flags); |
183 | } | |
c4f50183 | 184 | EXPORT_SYMBOL_GPL(tracing_off); |
033601a3 SR |
185 | |
186 | /** | |
187 | * tracing_off_permanent - permanently disable ring buffers | |
188 | * | |
189 | * This function, once called, will disable all ring buffers | |
c3706f00 | 190 | * permanently. |
033601a3 SR |
191 | */ |
192 | void tracing_off_permanent(void) | |
193 | { | |
194 | set_bit(RB_BUFFERS_DISABLED_BIT, &ring_buffer_flags); | |
a3583244 SR |
195 | } |
196 | ||
988ae9d6 SR |
197 | /** |
198 | * tracing_is_on - show state of ring buffers enabled | |
199 | */ | |
200 | int tracing_is_on(void) | |
201 | { | |
202 | return ring_buffer_flags == RB_BUFFERS_ON; | |
203 | } | |
204 | EXPORT_SYMBOL_GPL(tracing_is_on); | |
205 | ||
e3d6bf0a | 206 | #define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array)) |
67d34724 | 207 | #define RB_ALIGNMENT 4U |
334d4169 | 208 | #define RB_MAX_SMALL_DATA (RB_ALIGNMENT * RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
c7b09308 | 209 | #define RB_EVNT_MIN_SIZE 8U /* two 32bit words */ |
334d4169 | 210 | |
2271048d SR |
211 | #if !defined(CONFIG_64BIT) || defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) |
212 | # define RB_FORCE_8BYTE_ALIGNMENT 0 | |
213 | # define RB_ARCH_ALIGNMENT RB_ALIGNMENT | |
214 | #else | |
215 | # define RB_FORCE_8BYTE_ALIGNMENT 1 | |
216 | # define RB_ARCH_ALIGNMENT 8U | |
217 | #endif | |
218 | ||
334d4169 LJ |
219 | /* define RINGBUF_TYPE_DATA for 'case RINGBUF_TYPE_DATA:' */ |
220 | #define RINGBUF_TYPE_DATA 0 ... RINGBUF_TYPE_DATA_TYPE_LEN_MAX | |
7a8e76a3 SR |
221 | |
222 | enum { | |
223 | RB_LEN_TIME_EXTEND = 8, | |
224 | RB_LEN_TIME_STAMP = 16, | |
225 | }; | |
226 | ||
69d1b839 SR |
227 | #define skip_time_extend(event) \ |
228 | ((struct ring_buffer_event *)((char *)event + RB_LEN_TIME_EXTEND)) | |
229 | ||
2d622719 TZ |
230 | static inline int rb_null_event(struct ring_buffer_event *event) |
231 | { | |
a1863c21 | 232 | return event->type_len == RINGBUF_TYPE_PADDING && !event->time_delta; |
2d622719 TZ |
233 | } |
234 | ||
235 | static void rb_event_set_padding(struct ring_buffer_event *event) | |
236 | { | |
a1863c21 | 237 | /* padding has a NULL time_delta */ |
334d4169 | 238 | event->type_len = RINGBUF_TYPE_PADDING; |
2d622719 TZ |
239 | event->time_delta = 0; |
240 | } | |
241 | ||
34a148bf | 242 | static unsigned |
2d622719 | 243 | rb_event_data_length(struct ring_buffer_event *event) |
7a8e76a3 SR |
244 | { |
245 | unsigned length; | |
246 | ||
334d4169 LJ |
247 | if (event->type_len) |
248 | length = event->type_len * RB_ALIGNMENT; | |
2d622719 TZ |
249 | else |
250 | length = event->array[0]; | |
251 | return length + RB_EVNT_HDR_SIZE; | |
252 | } | |
253 | ||
69d1b839 SR |
254 | /* |
255 | * Return the length of the given event. Will return | |
256 | * the length of the time extend if the event is a | |
257 | * time extend. | |
258 | */ | |
259 | static inline unsigned | |
2d622719 TZ |
260 | rb_event_length(struct ring_buffer_event *event) |
261 | { | |
334d4169 | 262 | switch (event->type_len) { |
7a8e76a3 | 263 | case RINGBUF_TYPE_PADDING: |
2d622719 TZ |
264 | if (rb_null_event(event)) |
265 | /* undefined */ | |
266 | return -1; | |
334d4169 | 267 | return event->array[0] + RB_EVNT_HDR_SIZE; |
7a8e76a3 SR |
268 | |
269 | case RINGBUF_TYPE_TIME_EXTEND: | |
270 | return RB_LEN_TIME_EXTEND; | |
271 | ||
272 | case RINGBUF_TYPE_TIME_STAMP: | |
273 | return RB_LEN_TIME_STAMP; | |
274 | ||
275 | case RINGBUF_TYPE_DATA: | |
2d622719 | 276 | return rb_event_data_length(event); |
7a8e76a3 SR |
277 | default: |
278 | BUG(); | |
279 | } | |
280 | /* not hit */ | |
281 | return 0; | |
282 | } | |
283 | ||
69d1b839 SR |
284 | /* |
285 | * Return total length of time extend and data, | |
286 | * or just the event length for all other events. | |
287 | */ | |
288 | static inline unsigned | |
289 | rb_event_ts_length(struct ring_buffer_event *event) | |
290 | { | |
291 | unsigned len = 0; | |
292 | ||
293 | if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) { | |
294 | /* time extends include the data event after it */ | |
295 | len = RB_LEN_TIME_EXTEND; | |
296 | event = skip_time_extend(event); | |
297 | } | |
298 | return len + rb_event_length(event); | |
299 | } | |
300 | ||
7a8e76a3 SR |
301 | /** |
302 | * ring_buffer_event_length - return the length of the event | |
303 | * @event: the event to get the length of | |
69d1b839 SR |
304 | * |
305 | * Returns the size of the data load of a data event. | |
306 | * If the event is something other than a data event, it | |
307 | * returns the size of the event itself. With the exception | |
308 | * of a TIME EXTEND, where it still returns the size of the | |
309 | * data load of the data event after it. | |
7a8e76a3 SR |
310 | */ |
311 | unsigned ring_buffer_event_length(struct ring_buffer_event *event) | |
312 | { | |
69d1b839 SR |
313 | unsigned length; |
314 | ||
315 | if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) | |
316 | event = skip_time_extend(event); | |
317 | ||
318 | length = rb_event_length(event); | |
334d4169 | 319 | if (event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
465634ad RR |
320 | return length; |
321 | length -= RB_EVNT_HDR_SIZE; | |
322 | if (length > RB_MAX_SMALL_DATA + sizeof(event->array[0])) | |
323 | length -= sizeof(event->array[0]); | |
324 | return length; | |
7a8e76a3 | 325 | } |
c4f50183 | 326 | EXPORT_SYMBOL_GPL(ring_buffer_event_length); |
7a8e76a3 SR |
327 | |
328 | /* inline for ring buffer fast paths */ | |
34a148bf | 329 | static void * |
7a8e76a3 SR |
330 | rb_event_data(struct ring_buffer_event *event) |
331 | { | |
69d1b839 SR |
332 | if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) |
333 | event = skip_time_extend(event); | |
334d4169 | 334 | BUG_ON(event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX); |
7a8e76a3 | 335 | /* If length is in len field, then array[0] has the data */ |
334d4169 | 336 | if (event->type_len) |
7a8e76a3 SR |
337 | return (void *)&event->array[0]; |
338 | /* Otherwise length is in array[0] and array[1] has the data */ | |
339 | return (void *)&event->array[1]; | |
340 | } | |
341 | ||
342 | /** | |
343 | * ring_buffer_event_data - return the data of the event | |
344 | * @event: the event to get the data from | |
345 | */ | |
346 | void *ring_buffer_event_data(struct ring_buffer_event *event) | |
347 | { | |
348 | return rb_event_data(event); | |
349 | } | |
c4f50183 | 350 | EXPORT_SYMBOL_GPL(ring_buffer_event_data); |
7a8e76a3 SR |
351 | |
352 | #define for_each_buffer_cpu(buffer, cpu) \ | |
9e01c1b7 | 353 | for_each_cpu(cpu, buffer->cpumask) |
7a8e76a3 SR |
354 | |
355 | #define TS_SHIFT 27 | |
356 | #define TS_MASK ((1ULL << TS_SHIFT) - 1) | |
357 | #define TS_DELTA_TEST (~TS_MASK) | |
358 | ||
66a8cb95 SR |
359 | /* Flag when events were overwritten */ |
360 | #define RB_MISSED_EVENTS (1 << 31) | |
ff0ff84a SR |
361 | /* Missed count stored at end */ |
362 | #define RB_MISSED_STORED (1 << 30) | |
66a8cb95 | 363 | |
abc9b56d | 364 | struct buffer_data_page { |
e4c2ce82 | 365 | u64 time_stamp; /* page time stamp */ |
c3706f00 | 366 | local_t commit; /* write committed index */ |
abc9b56d SR |
367 | unsigned char data[]; /* data of buffer page */ |
368 | }; | |
369 | ||
77ae365e SR |
370 | /* |
371 | * Note, the buffer_page list must be first. The buffer pages | |
372 | * are allocated in cache lines, which means that each buffer | |
373 | * page will be at the beginning of a cache line, and thus | |
374 | * the least significant bits will be zero. We use this to | |
375 | * add flags in the list struct pointers, to make the ring buffer | |
376 | * lockless. | |
377 | */ | |
abc9b56d | 378 | struct buffer_page { |
778c55d4 | 379 | struct list_head list; /* list of buffer pages */ |
abc9b56d | 380 | local_t write; /* index for next write */ |
6f807acd | 381 | unsigned read; /* index for next read */ |
778c55d4 | 382 | local_t entries; /* entries on this page */ |
ff0ff84a | 383 | unsigned long real_end; /* real end of data */ |
abc9b56d | 384 | struct buffer_data_page *page; /* Actual data page */ |
7a8e76a3 SR |
385 | }; |
386 | ||
77ae365e SR |
387 | /* |
388 | * The buffer page counters, write and entries, must be reset | |
389 | * atomically when crossing page boundaries. To synchronize this | |
390 | * update, two counters are inserted into the number. One is | |
391 | * the actual counter for the write position or count on the page. | |
392 | * | |
393 | * The other is a counter of updaters. Before an update happens | |
394 | * the update partition of the counter is incremented. This will | |
395 | * allow the updater to update the counter atomically. | |
396 | * | |
397 | * The counter is 20 bits, and the state data is 12. | |
398 | */ | |
399 | #define RB_WRITE_MASK 0xfffff | |
400 | #define RB_WRITE_INTCNT (1 << 20) | |
401 | ||
044fa782 | 402 | static void rb_init_page(struct buffer_data_page *bpage) |
abc9b56d | 403 | { |
044fa782 | 404 | local_set(&bpage->commit, 0); |
abc9b56d SR |
405 | } |
406 | ||
474d32b6 SR |
407 | /** |
408 | * ring_buffer_page_len - the size of data on the page. | |
409 | * @page: The page to read | |
410 | * | |
411 | * Returns the amount of data on the page, including buffer page header. | |
412 | */ | |
ef7a4a16 SR |
413 | size_t ring_buffer_page_len(void *page) |
414 | { | |
474d32b6 SR |
415 | return local_read(&((struct buffer_data_page *)page)->commit) |
416 | + BUF_PAGE_HDR_SIZE; | |
ef7a4a16 SR |
417 | } |
418 | ||
ed56829c SR |
419 | /* |
420 | * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing | |
421 | * this issue out. | |
422 | */ | |
34a148bf | 423 | static void free_buffer_page(struct buffer_page *bpage) |
ed56829c | 424 | { |
34a148bf | 425 | free_page((unsigned long)bpage->page); |
e4c2ce82 | 426 | kfree(bpage); |
ed56829c SR |
427 | } |
428 | ||
7a8e76a3 SR |
429 | /* |
430 | * We need to fit the time_stamp delta into 27 bits. | |
431 | */ | |
432 | static inline int test_time_stamp(u64 delta) | |
433 | { | |
434 | if (delta & TS_DELTA_TEST) | |
435 | return 1; | |
436 | return 0; | |
437 | } | |
438 | ||
474d32b6 | 439 | #define BUF_PAGE_SIZE (PAGE_SIZE - BUF_PAGE_HDR_SIZE) |
7a8e76a3 | 440 | |
be957c44 SR |
441 | /* Max payload is BUF_PAGE_SIZE - header (8bytes) */ |
442 | #define BUF_MAX_DATA_SIZE (BUF_PAGE_SIZE - (sizeof(u32) * 2)) | |
443 | ||
d1b182a8 SR |
444 | int ring_buffer_print_page_header(struct trace_seq *s) |
445 | { | |
446 | struct buffer_data_page field; | |
447 | int ret; | |
448 | ||
449 | ret = trace_seq_printf(s, "\tfield: u64 timestamp;\t" | |
26a50744 TZ |
450 | "offset:0;\tsize:%u;\tsigned:%u;\n", |
451 | (unsigned int)sizeof(field.time_stamp), | |
452 | (unsigned int)is_signed_type(u64)); | |
d1b182a8 SR |
453 | |
454 | ret = trace_seq_printf(s, "\tfield: local_t commit;\t" | |
26a50744 | 455 | "offset:%u;\tsize:%u;\tsigned:%u;\n", |
d1b182a8 | 456 | (unsigned int)offsetof(typeof(field), commit), |
26a50744 TZ |
457 | (unsigned int)sizeof(field.commit), |
458 | (unsigned int)is_signed_type(long)); | |
d1b182a8 | 459 | |
66a8cb95 SR |
460 | ret = trace_seq_printf(s, "\tfield: int overwrite;\t" |
461 | "offset:%u;\tsize:%u;\tsigned:%u;\n", | |
462 | (unsigned int)offsetof(typeof(field), commit), | |
463 | 1, | |
464 | (unsigned int)is_signed_type(long)); | |
465 | ||
d1b182a8 | 466 | ret = trace_seq_printf(s, "\tfield: char data;\t" |
26a50744 | 467 | "offset:%u;\tsize:%u;\tsigned:%u;\n", |
d1b182a8 | 468 | (unsigned int)offsetof(typeof(field), data), |
26a50744 TZ |
469 | (unsigned int)BUF_PAGE_SIZE, |
470 | (unsigned int)is_signed_type(char)); | |
d1b182a8 SR |
471 | |
472 | return ret; | |
473 | } | |
474 | ||
7a8e76a3 SR |
475 | /* |
476 | * head_page == tail_page && head == tail then buffer is empty. | |
477 | */ | |
478 | struct ring_buffer_per_cpu { | |
479 | int cpu; | |
985023de | 480 | atomic_t record_disabled; |
7a8e76a3 | 481 | struct ring_buffer *buffer; |
77ae365e | 482 | spinlock_t reader_lock; /* serialize readers */ |
445c8951 | 483 | arch_spinlock_t lock; |
7a8e76a3 | 484 | struct lock_class_key lock_key; |
3adc54fa | 485 | struct list_head *pages; |
6f807acd SR |
486 | struct buffer_page *head_page; /* read from head */ |
487 | struct buffer_page *tail_page; /* write to tail */ | |
c3706f00 | 488 | struct buffer_page *commit_page; /* committed pages */ |
d769041f | 489 | struct buffer_page *reader_page; |
66a8cb95 SR |
490 | unsigned long lost_events; |
491 | unsigned long last_overrun; | |
77ae365e SR |
492 | local_t commit_overrun; |
493 | local_t overrun; | |
e4906eff | 494 | local_t entries; |
fa743953 SR |
495 | local_t committing; |
496 | local_t commits; | |
77ae365e | 497 | unsigned long read; |
7a8e76a3 SR |
498 | u64 write_stamp; |
499 | u64 read_stamp; | |
7a8e76a3 SR |
500 | }; |
501 | ||
502 | struct ring_buffer { | |
7a8e76a3 SR |
503 | unsigned pages; |
504 | unsigned flags; | |
505 | int cpus; | |
7a8e76a3 | 506 | atomic_t record_disabled; |
00f62f61 | 507 | cpumask_var_t cpumask; |
7a8e76a3 | 508 | |
1f8a6a10 PZ |
509 | struct lock_class_key *reader_lock_key; |
510 | ||
7a8e76a3 SR |
511 | struct mutex mutex; |
512 | ||
513 | struct ring_buffer_per_cpu **buffers; | |
554f786e | 514 | |
59222efe | 515 | #ifdef CONFIG_HOTPLUG_CPU |
554f786e SR |
516 | struct notifier_block cpu_notify; |
517 | #endif | |
37886f6a | 518 | u64 (*clock)(void); |
7a8e76a3 SR |
519 | }; |
520 | ||
521 | struct ring_buffer_iter { | |
522 | struct ring_buffer_per_cpu *cpu_buffer; | |
523 | unsigned long head; | |
524 | struct buffer_page *head_page; | |
492a74f4 SR |
525 | struct buffer_page *cache_reader_page; |
526 | unsigned long cache_read; | |
7a8e76a3 SR |
527 | u64 read_stamp; |
528 | }; | |
529 | ||
f536aafc | 530 | /* buffer may be either ring_buffer or ring_buffer_per_cpu */ |
077c5407 SR |
531 | #define RB_WARN_ON(b, cond) \ |
532 | ({ \ | |
533 | int _____ret = unlikely(cond); \ | |
534 | if (_____ret) { \ | |
535 | if (__same_type(*(b), struct ring_buffer_per_cpu)) { \ | |
536 | struct ring_buffer_per_cpu *__b = \ | |
537 | (void *)b; \ | |
538 | atomic_inc(&__b->buffer->record_disabled); \ | |
539 | } else \ | |
540 | atomic_inc(&b->record_disabled); \ | |
541 | WARN_ON(1); \ | |
542 | } \ | |
543 | _____ret; \ | |
3e89c7bb | 544 | }) |
f536aafc | 545 | |
37886f6a SR |
546 | /* Up this if you want to test the TIME_EXTENTS and normalization */ |
547 | #define DEBUG_SHIFT 0 | |
548 | ||
6d3f1e12 | 549 | static inline u64 rb_time_stamp(struct ring_buffer *buffer) |
88eb0125 SR |
550 | { |
551 | /* shift to debug/test normalization and TIME_EXTENTS */ | |
552 | return buffer->clock() << DEBUG_SHIFT; | |
553 | } | |
554 | ||
37886f6a SR |
555 | u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu) |
556 | { | |
557 | u64 time; | |
558 | ||
559 | preempt_disable_notrace(); | |
6d3f1e12 | 560 | time = rb_time_stamp(buffer); |
37886f6a SR |
561 | preempt_enable_no_resched_notrace(); |
562 | ||
563 | return time; | |
564 | } | |
565 | EXPORT_SYMBOL_GPL(ring_buffer_time_stamp); | |
566 | ||
567 | void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer, | |
568 | int cpu, u64 *ts) | |
569 | { | |
570 | /* Just stupid testing the normalize function and deltas */ | |
571 | *ts >>= DEBUG_SHIFT; | |
572 | } | |
573 | EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp); | |
574 | ||
77ae365e SR |
575 | /* |
576 | * Making the ring buffer lockless makes things tricky. | |
577 | * Although writes only happen on the CPU that they are on, | |
578 | * and they only need to worry about interrupts. Reads can | |
579 | * happen on any CPU. | |
580 | * | |
581 | * The reader page is always off the ring buffer, but when the | |
582 | * reader finishes with a page, it needs to swap its page with | |
583 | * a new one from the buffer. The reader needs to take from | |
584 | * the head (writes go to the tail). But if a writer is in overwrite | |
585 | * mode and wraps, it must push the head page forward. | |
586 | * | |
587 | * Here lies the problem. | |
588 | * | |
589 | * The reader must be careful to replace only the head page, and | |
590 | * not another one. As described at the top of the file in the | |
591 | * ASCII art, the reader sets its old page to point to the next | |
592 | * page after head. It then sets the page after head to point to | |
593 | * the old reader page. But if the writer moves the head page | |
594 | * during this operation, the reader could end up with the tail. | |
595 | * | |
596 | * We use cmpxchg to help prevent this race. We also do something | |
597 | * special with the page before head. We set the LSB to 1. | |
598 | * | |
599 | * When the writer must push the page forward, it will clear the | |
600 | * bit that points to the head page, move the head, and then set | |
601 | * the bit that points to the new head page. | |
602 | * | |
603 | * We also don't want an interrupt coming in and moving the head | |
604 | * page on another writer. Thus we use the second LSB to catch | |
605 | * that too. Thus: | |
606 | * | |
607 | * head->list->prev->next bit 1 bit 0 | |
608 | * ------- ------- | |
609 | * Normal page 0 0 | |
610 | * Points to head page 0 1 | |
611 | * New head page 1 0 | |
612 | * | |
613 | * Note we can not trust the prev pointer of the head page, because: | |
614 | * | |
615 | * +----+ +-----+ +-----+ | |
616 | * | |------>| T |---X--->| N | | |
617 | * | |<------| | | | | |
618 | * +----+ +-----+ +-----+ | |
619 | * ^ ^ | | |
620 | * | +-----+ | | | |
621 | * +----------| R |----------+ | | |
622 | * | |<-----------+ | |
623 | * +-----+ | |
624 | * | |
625 | * Key: ---X--> HEAD flag set in pointer | |
626 | * T Tail page | |
627 | * R Reader page | |
628 | * N Next page | |
629 | * | |
630 | * (see __rb_reserve_next() to see where this happens) | |
631 | * | |
632 | * What the above shows is that the reader just swapped out | |
633 | * the reader page with a page in the buffer, but before it | |
634 | * could make the new header point back to the new page added | |
635 | * it was preempted by a writer. The writer moved forward onto | |
636 | * the new page added by the reader and is about to move forward | |
637 | * again. | |
638 | * | |
639 | * You can see, it is legitimate for the previous pointer of | |
640 | * the head (or any page) not to point back to itself. But only | |
641 | * temporarially. | |
642 | */ | |
643 | ||
644 | #define RB_PAGE_NORMAL 0UL | |
645 | #define RB_PAGE_HEAD 1UL | |
646 | #define RB_PAGE_UPDATE 2UL | |
647 | ||
648 | ||
649 | #define RB_FLAG_MASK 3UL | |
650 | ||
651 | /* PAGE_MOVED is not part of the mask */ | |
652 | #define RB_PAGE_MOVED 4UL | |
653 | ||
654 | /* | |
655 | * rb_list_head - remove any bit | |
656 | */ | |
657 | static struct list_head *rb_list_head(struct list_head *list) | |
658 | { | |
659 | unsigned long val = (unsigned long)list; | |
660 | ||
661 | return (struct list_head *)(val & ~RB_FLAG_MASK); | |
662 | } | |
663 | ||
664 | /* | |
6d3f1e12 | 665 | * rb_is_head_page - test if the given page is the head page |
77ae365e SR |
666 | * |
667 | * Because the reader may move the head_page pointer, we can | |
668 | * not trust what the head page is (it may be pointing to | |
669 | * the reader page). But if the next page is a header page, | |
670 | * its flags will be non zero. | |
671 | */ | |
672 | static int inline | |
673 | rb_is_head_page(struct ring_buffer_per_cpu *cpu_buffer, | |
674 | struct buffer_page *page, struct list_head *list) | |
675 | { | |
676 | unsigned long val; | |
677 | ||
678 | val = (unsigned long)list->next; | |
679 | ||
680 | if ((val & ~RB_FLAG_MASK) != (unsigned long)&page->list) | |
681 | return RB_PAGE_MOVED; | |
682 | ||
683 | return val & RB_FLAG_MASK; | |
684 | } | |
685 | ||
686 | /* | |
687 | * rb_is_reader_page | |
688 | * | |
689 | * The unique thing about the reader page, is that, if the | |
690 | * writer is ever on it, the previous pointer never points | |
691 | * back to the reader page. | |
692 | */ | |
693 | static int rb_is_reader_page(struct buffer_page *page) | |
694 | { | |
695 | struct list_head *list = page->list.prev; | |
696 | ||
697 | return rb_list_head(list->next) != &page->list; | |
698 | } | |
699 | ||
700 | /* | |
701 | * rb_set_list_to_head - set a list_head to be pointing to head. | |
702 | */ | |
703 | static void rb_set_list_to_head(struct ring_buffer_per_cpu *cpu_buffer, | |
704 | struct list_head *list) | |
705 | { | |
706 | unsigned long *ptr; | |
707 | ||
708 | ptr = (unsigned long *)&list->next; | |
709 | *ptr |= RB_PAGE_HEAD; | |
710 | *ptr &= ~RB_PAGE_UPDATE; | |
711 | } | |
712 | ||
713 | /* | |
714 | * rb_head_page_activate - sets up head page | |
715 | */ | |
716 | static void rb_head_page_activate(struct ring_buffer_per_cpu *cpu_buffer) | |
717 | { | |
718 | struct buffer_page *head; | |
719 | ||
720 | head = cpu_buffer->head_page; | |
721 | if (!head) | |
722 | return; | |
723 | ||
724 | /* | |
725 | * Set the previous list pointer to have the HEAD flag. | |
726 | */ | |
727 | rb_set_list_to_head(cpu_buffer, head->list.prev); | |
728 | } | |
729 | ||
730 | static void rb_list_head_clear(struct list_head *list) | |
731 | { | |
732 | unsigned long *ptr = (unsigned long *)&list->next; | |
733 | ||
734 | *ptr &= ~RB_FLAG_MASK; | |
735 | } | |
736 | ||
737 | /* | |
738 | * rb_head_page_dactivate - clears head page ptr (for free list) | |
739 | */ | |
740 | static void | |
741 | rb_head_page_deactivate(struct ring_buffer_per_cpu *cpu_buffer) | |
742 | { | |
743 | struct list_head *hd; | |
744 | ||
745 | /* Go through the whole list and clear any pointers found. */ | |
746 | rb_list_head_clear(cpu_buffer->pages); | |
747 | ||
748 | list_for_each(hd, cpu_buffer->pages) | |
749 | rb_list_head_clear(hd); | |
750 | } | |
751 | ||
752 | static int rb_head_page_set(struct ring_buffer_per_cpu *cpu_buffer, | |
753 | struct buffer_page *head, | |
754 | struct buffer_page *prev, | |
755 | int old_flag, int new_flag) | |
756 | { | |
757 | struct list_head *list; | |
758 | unsigned long val = (unsigned long)&head->list; | |
759 | unsigned long ret; | |
760 | ||
761 | list = &prev->list; | |
762 | ||
763 | val &= ~RB_FLAG_MASK; | |
764 | ||
08a40816 SR |
765 | ret = cmpxchg((unsigned long *)&list->next, |
766 | val | old_flag, val | new_flag); | |
77ae365e SR |
767 | |
768 | /* check if the reader took the page */ | |
769 | if ((ret & ~RB_FLAG_MASK) != val) | |
770 | return RB_PAGE_MOVED; | |
771 | ||
772 | return ret & RB_FLAG_MASK; | |
773 | } | |
774 | ||
775 | static int rb_head_page_set_update(struct ring_buffer_per_cpu *cpu_buffer, | |
776 | struct buffer_page *head, | |
777 | struct buffer_page *prev, | |
778 | int old_flag) | |
779 | { | |
780 | return rb_head_page_set(cpu_buffer, head, prev, | |
781 | old_flag, RB_PAGE_UPDATE); | |
782 | } | |
783 | ||
784 | static int rb_head_page_set_head(struct ring_buffer_per_cpu *cpu_buffer, | |
785 | struct buffer_page *head, | |
786 | struct buffer_page *prev, | |
787 | int old_flag) | |
788 | { | |
789 | return rb_head_page_set(cpu_buffer, head, prev, | |
790 | old_flag, RB_PAGE_HEAD); | |
791 | } | |
792 | ||
793 | static int rb_head_page_set_normal(struct ring_buffer_per_cpu *cpu_buffer, | |
794 | struct buffer_page *head, | |
795 | struct buffer_page *prev, | |
796 | int old_flag) | |
797 | { | |
798 | return rb_head_page_set(cpu_buffer, head, prev, | |
799 | old_flag, RB_PAGE_NORMAL); | |
800 | } | |
801 | ||
802 | static inline void rb_inc_page(struct ring_buffer_per_cpu *cpu_buffer, | |
803 | struct buffer_page **bpage) | |
804 | { | |
805 | struct list_head *p = rb_list_head((*bpage)->list.next); | |
806 | ||
807 | *bpage = list_entry(p, struct buffer_page, list); | |
808 | } | |
809 | ||
810 | static struct buffer_page * | |
811 | rb_set_head_page(struct ring_buffer_per_cpu *cpu_buffer) | |
812 | { | |
813 | struct buffer_page *head; | |
814 | struct buffer_page *page; | |
815 | struct list_head *list; | |
816 | int i; | |
817 | ||
818 | if (RB_WARN_ON(cpu_buffer, !cpu_buffer->head_page)) | |
819 | return NULL; | |
820 | ||
821 | /* sanity check */ | |
822 | list = cpu_buffer->pages; | |
823 | if (RB_WARN_ON(cpu_buffer, rb_list_head(list->prev->next) != list)) | |
824 | return NULL; | |
825 | ||
826 | page = head = cpu_buffer->head_page; | |
827 | /* | |
828 | * It is possible that the writer moves the header behind | |
829 | * where we started, and we miss in one loop. | |
830 | * A second loop should grab the header, but we'll do | |
831 | * three loops just because I'm paranoid. | |
832 | */ | |
833 | for (i = 0; i < 3; i++) { | |
834 | do { | |
835 | if (rb_is_head_page(cpu_buffer, page, page->list.prev)) { | |
836 | cpu_buffer->head_page = page; | |
837 | return page; | |
838 | } | |
839 | rb_inc_page(cpu_buffer, &page); | |
840 | } while (page != head); | |
841 | } | |
842 | ||
843 | RB_WARN_ON(cpu_buffer, 1); | |
844 | ||
845 | return NULL; | |
846 | } | |
847 | ||
848 | static int rb_head_page_replace(struct buffer_page *old, | |
849 | struct buffer_page *new) | |
850 | { | |
851 | unsigned long *ptr = (unsigned long *)&old->list.prev->next; | |
852 | unsigned long val; | |
853 | unsigned long ret; | |
854 | ||
855 | val = *ptr & ~RB_FLAG_MASK; | |
856 | val |= RB_PAGE_HEAD; | |
857 | ||
08a40816 | 858 | ret = cmpxchg(ptr, val, (unsigned long)&new->list); |
77ae365e SR |
859 | |
860 | return ret == val; | |
861 | } | |
862 | ||
863 | /* | |
864 | * rb_tail_page_update - move the tail page forward | |
865 | * | |
866 | * Returns 1 if moved tail page, 0 if someone else did. | |
867 | */ | |
868 | static int rb_tail_page_update(struct ring_buffer_per_cpu *cpu_buffer, | |
869 | struct buffer_page *tail_page, | |
870 | struct buffer_page *next_page) | |
871 | { | |
872 | struct buffer_page *old_tail; | |
873 | unsigned long old_entries; | |
874 | unsigned long old_write; | |
875 | int ret = 0; | |
876 | ||
877 | /* | |
878 | * The tail page now needs to be moved forward. | |
879 | * | |
880 | * We need to reset the tail page, but without messing | |
881 | * with possible erasing of data brought in by interrupts | |
882 | * that have moved the tail page and are currently on it. | |
883 | * | |
884 | * We add a counter to the write field to denote this. | |
885 | */ | |
886 | old_write = local_add_return(RB_WRITE_INTCNT, &next_page->write); | |
887 | old_entries = local_add_return(RB_WRITE_INTCNT, &next_page->entries); | |
888 | ||
889 | /* | |
890 | * Just make sure we have seen our old_write and synchronize | |
891 | * with any interrupts that come in. | |
892 | */ | |
893 | barrier(); | |
894 | ||
895 | /* | |
896 | * If the tail page is still the same as what we think | |
897 | * it is, then it is up to us to update the tail | |
898 | * pointer. | |
899 | */ | |
900 | if (tail_page == cpu_buffer->tail_page) { | |
901 | /* Zero the write counter */ | |
902 | unsigned long val = old_write & ~RB_WRITE_MASK; | |
903 | unsigned long eval = old_entries & ~RB_WRITE_MASK; | |
904 | ||
905 | /* | |
906 | * This will only succeed if an interrupt did | |
907 | * not come in and change it. In which case, we | |
908 | * do not want to modify it. | |
da706d8b LJ |
909 | * |
910 | * We add (void) to let the compiler know that we do not care | |
911 | * about the return value of these functions. We use the | |
912 | * cmpxchg to only update if an interrupt did not already | |
913 | * do it for us. If the cmpxchg fails, we don't care. | |
77ae365e | 914 | */ |
da706d8b LJ |
915 | (void)local_cmpxchg(&next_page->write, old_write, val); |
916 | (void)local_cmpxchg(&next_page->entries, old_entries, eval); | |
77ae365e SR |
917 | |
918 | /* | |
919 | * No need to worry about races with clearing out the commit. | |
920 | * it only can increment when a commit takes place. But that | |
921 | * only happens in the outer most nested commit. | |
922 | */ | |
923 | local_set(&next_page->page->commit, 0); | |
924 | ||
925 | old_tail = cmpxchg(&cpu_buffer->tail_page, | |
926 | tail_page, next_page); | |
927 | ||
928 | if (old_tail == tail_page) | |
929 | ret = 1; | |
930 | } | |
931 | ||
932 | return ret; | |
933 | } | |
934 | ||
935 | static int rb_check_bpage(struct ring_buffer_per_cpu *cpu_buffer, | |
936 | struct buffer_page *bpage) | |
937 | { | |
938 | unsigned long val = (unsigned long)bpage; | |
939 | ||
940 | if (RB_WARN_ON(cpu_buffer, val & RB_FLAG_MASK)) | |
941 | return 1; | |
942 | ||
943 | return 0; | |
944 | } | |
945 | ||
946 | /** | |
947 | * rb_check_list - make sure a pointer to a list has the last bits zero | |
948 | */ | |
949 | static int rb_check_list(struct ring_buffer_per_cpu *cpu_buffer, | |
950 | struct list_head *list) | |
951 | { | |
952 | if (RB_WARN_ON(cpu_buffer, rb_list_head(list->prev) != list->prev)) | |
953 | return 1; | |
954 | if (RB_WARN_ON(cpu_buffer, rb_list_head(list->next) != list->next)) | |
955 | return 1; | |
956 | return 0; | |
957 | } | |
958 | ||
7a8e76a3 SR |
959 | /** |
960 | * check_pages - integrity check of buffer pages | |
961 | * @cpu_buffer: CPU buffer with pages to test | |
962 | * | |
c3706f00 | 963 | * As a safety measure we check to make sure the data pages have not |
7a8e76a3 SR |
964 | * been corrupted. |
965 | */ | |
966 | static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) | |
967 | { | |
3adc54fa | 968 | struct list_head *head = cpu_buffer->pages; |
044fa782 | 969 | struct buffer_page *bpage, *tmp; |
7a8e76a3 | 970 | |
77ae365e SR |
971 | rb_head_page_deactivate(cpu_buffer); |
972 | ||
3e89c7bb SR |
973 | if (RB_WARN_ON(cpu_buffer, head->next->prev != head)) |
974 | return -1; | |
975 | if (RB_WARN_ON(cpu_buffer, head->prev->next != head)) | |
976 | return -1; | |
7a8e76a3 | 977 | |
77ae365e SR |
978 | if (rb_check_list(cpu_buffer, head)) |
979 | return -1; | |
980 | ||
044fa782 | 981 | list_for_each_entry_safe(bpage, tmp, head, list) { |
3e89c7bb | 982 | if (RB_WARN_ON(cpu_buffer, |
044fa782 | 983 | bpage->list.next->prev != &bpage->list)) |
3e89c7bb SR |
984 | return -1; |
985 | if (RB_WARN_ON(cpu_buffer, | |
044fa782 | 986 | bpage->list.prev->next != &bpage->list)) |
3e89c7bb | 987 | return -1; |
77ae365e SR |
988 | if (rb_check_list(cpu_buffer, &bpage->list)) |
989 | return -1; | |
7a8e76a3 SR |
990 | } |
991 | ||
77ae365e SR |
992 | rb_head_page_activate(cpu_buffer); |
993 | ||
7a8e76a3 SR |
994 | return 0; |
995 | } | |
996 | ||
7a8e76a3 SR |
997 | static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, |
998 | unsigned nr_pages) | |
999 | { | |
044fa782 | 1000 | struct buffer_page *bpage, *tmp; |
7a8e76a3 SR |
1001 | unsigned long addr; |
1002 | LIST_HEAD(pages); | |
1003 | unsigned i; | |
1004 | ||
3adc54fa SR |
1005 | WARN_ON(!nr_pages); |
1006 | ||
7a8e76a3 | 1007 | for (i = 0; i < nr_pages; i++) { |
044fa782 | 1008 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
aa1e0e3b | 1009 | GFP_KERNEL, cpu_to_node(cpu_buffer->cpu)); |
044fa782 | 1010 | if (!bpage) |
e4c2ce82 | 1011 | goto free_pages; |
77ae365e SR |
1012 | |
1013 | rb_check_bpage(cpu_buffer, bpage); | |
1014 | ||
044fa782 | 1015 | list_add(&bpage->list, &pages); |
e4c2ce82 | 1016 | |
7a8e76a3 SR |
1017 | addr = __get_free_page(GFP_KERNEL); |
1018 | if (!addr) | |
1019 | goto free_pages; | |
044fa782 SR |
1020 | bpage->page = (void *)addr; |
1021 | rb_init_page(bpage->page); | |
7a8e76a3 SR |
1022 | } |
1023 | ||
3adc54fa SR |
1024 | /* |
1025 | * The ring buffer page list is a circular list that does not | |
1026 | * start and end with a list head. All page list items point to | |
1027 | * other pages. | |
1028 | */ | |
1029 | cpu_buffer->pages = pages.next; | |
1030 | list_del(&pages); | |
7a8e76a3 SR |
1031 | |
1032 | rb_check_pages(cpu_buffer); | |
1033 | ||
1034 | return 0; | |
1035 | ||
1036 | free_pages: | |
044fa782 SR |
1037 | list_for_each_entry_safe(bpage, tmp, &pages, list) { |
1038 | list_del_init(&bpage->list); | |
1039 | free_buffer_page(bpage); | |
7a8e76a3 SR |
1040 | } |
1041 | return -ENOMEM; | |
1042 | } | |
1043 | ||
1044 | static struct ring_buffer_per_cpu * | |
1045 | rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu) | |
1046 | { | |
1047 | struct ring_buffer_per_cpu *cpu_buffer; | |
044fa782 | 1048 | struct buffer_page *bpage; |
d769041f | 1049 | unsigned long addr; |
7a8e76a3 SR |
1050 | int ret; |
1051 | ||
1052 | cpu_buffer = kzalloc_node(ALIGN(sizeof(*cpu_buffer), cache_line_size()), | |
1053 | GFP_KERNEL, cpu_to_node(cpu)); | |
1054 | if (!cpu_buffer) | |
1055 | return NULL; | |
1056 | ||
1057 | cpu_buffer->cpu = cpu; | |
1058 | cpu_buffer->buffer = buffer; | |
f83c9d0f | 1059 | spin_lock_init(&cpu_buffer->reader_lock); |
1f8a6a10 | 1060 | lockdep_set_class(&cpu_buffer->reader_lock, buffer->reader_lock_key); |
edc35bd7 | 1061 | cpu_buffer->lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; |
7a8e76a3 | 1062 | |
044fa782 | 1063 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
e4c2ce82 | 1064 | GFP_KERNEL, cpu_to_node(cpu)); |
044fa782 | 1065 | if (!bpage) |
e4c2ce82 SR |
1066 | goto fail_free_buffer; |
1067 | ||
77ae365e SR |
1068 | rb_check_bpage(cpu_buffer, bpage); |
1069 | ||
044fa782 | 1070 | cpu_buffer->reader_page = bpage; |
d769041f SR |
1071 | addr = __get_free_page(GFP_KERNEL); |
1072 | if (!addr) | |
e4c2ce82 | 1073 | goto fail_free_reader; |
044fa782 SR |
1074 | bpage->page = (void *)addr; |
1075 | rb_init_page(bpage->page); | |
e4c2ce82 | 1076 | |
d769041f | 1077 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); |
d769041f | 1078 | |
7a8e76a3 SR |
1079 | ret = rb_allocate_pages(cpu_buffer, buffer->pages); |
1080 | if (ret < 0) | |
d769041f | 1081 | goto fail_free_reader; |
7a8e76a3 SR |
1082 | |
1083 | cpu_buffer->head_page | |
3adc54fa | 1084 | = list_entry(cpu_buffer->pages, struct buffer_page, list); |
bf41a158 | 1085 | cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; |
7a8e76a3 | 1086 | |
77ae365e SR |
1087 | rb_head_page_activate(cpu_buffer); |
1088 | ||
7a8e76a3 SR |
1089 | return cpu_buffer; |
1090 | ||
d769041f SR |
1091 | fail_free_reader: |
1092 | free_buffer_page(cpu_buffer->reader_page); | |
1093 | ||
7a8e76a3 SR |
1094 | fail_free_buffer: |
1095 | kfree(cpu_buffer); | |
1096 | return NULL; | |
1097 | } | |
1098 | ||
1099 | static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) | |
1100 | { | |
3adc54fa | 1101 | struct list_head *head = cpu_buffer->pages; |
044fa782 | 1102 | struct buffer_page *bpage, *tmp; |
7a8e76a3 | 1103 | |
d769041f SR |
1104 | free_buffer_page(cpu_buffer->reader_page); |
1105 | ||
77ae365e SR |
1106 | rb_head_page_deactivate(cpu_buffer); |
1107 | ||
3adc54fa SR |
1108 | if (head) { |
1109 | list_for_each_entry_safe(bpage, tmp, head, list) { | |
1110 | list_del_init(&bpage->list); | |
1111 | free_buffer_page(bpage); | |
1112 | } | |
1113 | bpage = list_entry(head, struct buffer_page, list); | |
044fa782 | 1114 | free_buffer_page(bpage); |
7a8e76a3 | 1115 | } |
3adc54fa | 1116 | |
7a8e76a3 SR |
1117 | kfree(cpu_buffer); |
1118 | } | |
1119 | ||
59222efe | 1120 | #ifdef CONFIG_HOTPLUG_CPU |
09c9e84d FW |
1121 | static int rb_cpu_notify(struct notifier_block *self, |
1122 | unsigned long action, void *hcpu); | |
554f786e SR |
1123 | #endif |
1124 | ||
7a8e76a3 SR |
1125 | /** |
1126 | * ring_buffer_alloc - allocate a new ring_buffer | |
68814b58 | 1127 | * @size: the size in bytes per cpu that is needed. |
7a8e76a3 SR |
1128 | * @flags: attributes to set for the ring buffer. |
1129 | * | |
1130 | * Currently the only flag that is available is the RB_FL_OVERWRITE | |
1131 | * flag. This flag means that the buffer will overwrite old data | |
1132 | * when the buffer wraps. If this flag is not set, the buffer will | |
1133 | * drop data when the tail hits the head. | |
1134 | */ | |
1f8a6a10 PZ |
1135 | struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, |
1136 | struct lock_class_key *key) | |
7a8e76a3 SR |
1137 | { |
1138 | struct ring_buffer *buffer; | |
1139 | int bsize; | |
1140 | int cpu; | |
1141 | ||
1142 | /* keep it in its own cache line */ | |
1143 | buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()), | |
1144 | GFP_KERNEL); | |
1145 | if (!buffer) | |
1146 | return NULL; | |
1147 | ||
9e01c1b7 RR |
1148 | if (!alloc_cpumask_var(&buffer->cpumask, GFP_KERNEL)) |
1149 | goto fail_free_buffer; | |
1150 | ||
7a8e76a3 SR |
1151 | buffer->pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
1152 | buffer->flags = flags; | |
37886f6a | 1153 | buffer->clock = trace_clock_local; |
1f8a6a10 | 1154 | buffer->reader_lock_key = key; |
7a8e76a3 SR |
1155 | |
1156 | /* need at least two pages */ | |
5f78abee SR |
1157 | if (buffer->pages < 2) |
1158 | buffer->pages = 2; | |
7a8e76a3 | 1159 | |
3bf832ce FW |
1160 | /* |
1161 | * In case of non-hotplug cpu, if the ring-buffer is allocated | |
1162 | * in early initcall, it will not be notified of secondary cpus. | |
1163 | * In that off case, we need to allocate for all possible cpus. | |
1164 | */ | |
1165 | #ifdef CONFIG_HOTPLUG_CPU | |
554f786e SR |
1166 | get_online_cpus(); |
1167 | cpumask_copy(buffer->cpumask, cpu_online_mask); | |
3bf832ce FW |
1168 | #else |
1169 | cpumask_copy(buffer->cpumask, cpu_possible_mask); | |
1170 | #endif | |
7a8e76a3 SR |
1171 | buffer->cpus = nr_cpu_ids; |
1172 | ||
1173 | bsize = sizeof(void *) * nr_cpu_ids; | |
1174 | buffer->buffers = kzalloc(ALIGN(bsize, cache_line_size()), | |
1175 | GFP_KERNEL); | |
1176 | if (!buffer->buffers) | |
9e01c1b7 | 1177 | goto fail_free_cpumask; |
7a8e76a3 SR |
1178 | |
1179 | for_each_buffer_cpu(buffer, cpu) { | |
1180 | buffer->buffers[cpu] = | |
1181 | rb_allocate_cpu_buffer(buffer, cpu); | |
1182 | if (!buffer->buffers[cpu]) | |
1183 | goto fail_free_buffers; | |
1184 | } | |
1185 | ||
59222efe | 1186 | #ifdef CONFIG_HOTPLUG_CPU |
554f786e SR |
1187 | buffer->cpu_notify.notifier_call = rb_cpu_notify; |
1188 | buffer->cpu_notify.priority = 0; | |
1189 | register_cpu_notifier(&buffer->cpu_notify); | |
1190 | #endif | |
1191 | ||
1192 | put_online_cpus(); | |
7a8e76a3 SR |
1193 | mutex_init(&buffer->mutex); |
1194 | ||
1195 | return buffer; | |
1196 | ||
1197 | fail_free_buffers: | |
1198 | for_each_buffer_cpu(buffer, cpu) { | |
1199 | if (buffer->buffers[cpu]) | |
1200 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
1201 | } | |
1202 | kfree(buffer->buffers); | |
1203 | ||
9e01c1b7 RR |
1204 | fail_free_cpumask: |
1205 | free_cpumask_var(buffer->cpumask); | |
554f786e | 1206 | put_online_cpus(); |
9e01c1b7 | 1207 | |
7a8e76a3 SR |
1208 | fail_free_buffer: |
1209 | kfree(buffer); | |
1210 | return NULL; | |
1211 | } | |
1f8a6a10 | 1212 | EXPORT_SYMBOL_GPL(__ring_buffer_alloc); |
7a8e76a3 SR |
1213 | |
1214 | /** | |
1215 | * ring_buffer_free - free a ring buffer. | |
1216 | * @buffer: the buffer to free. | |
1217 | */ | |
1218 | void | |
1219 | ring_buffer_free(struct ring_buffer *buffer) | |
1220 | { | |
1221 | int cpu; | |
1222 | ||
554f786e SR |
1223 | get_online_cpus(); |
1224 | ||
59222efe | 1225 | #ifdef CONFIG_HOTPLUG_CPU |
554f786e SR |
1226 | unregister_cpu_notifier(&buffer->cpu_notify); |
1227 | #endif | |
1228 | ||
7a8e76a3 SR |
1229 | for_each_buffer_cpu(buffer, cpu) |
1230 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
1231 | ||
554f786e SR |
1232 | put_online_cpus(); |
1233 | ||
bd3f0221 | 1234 | kfree(buffer->buffers); |
9e01c1b7 RR |
1235 | free_cpumask_var(buffer->cpumask); |
1236 | ||
7a8e76a3 SR |
1237 | kfree(buffer); |
1238 | } | |
c4f50183 | 1239 | EXPORT_SYMBOL_GPL(ring_buffer_free); |
7a8e76a3 | 1240 | |
37886f6a SR |
1241 | void ring_buffer_set_clock(struct ring_buffer *buffer, |
1242 | u64 (*clock)(void)) | |
1243 | { | |
1244 | buffer->clock = clock; | |
1245 | } | |
1246 | ||
7a8e76a3 SR |
1247 | static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer); |
1248 | ||
1249 | static void | |
1250 | rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages) | |
1251 | { | |
044fa782 | 1252 | struct buffer_page *bpage; |
7a8e76a3 SR |
1253 | struct list_head *p; |
1254 | unsigned i; | |
1255 | ||
f7112949 | 1256 | spin_lock_irq(&cpu_buffer->reader_lock); |
77ae365e SR |
1257 | rb_head_page_deactivate(cpu_buffer); |
1258 | ||
7a8e76a3 | 1259 | for (i = 0; i < nr_pages; i++) { |
3adc54fa | 1260 | if (RB_WARN_ON(cpu_buffer, list_empty(cpu_buffer->pages))) |
292f60c0 | 1261 | goto out; |
3adc54fa | 1262 | p = cpu_buffer->pages->next; |
044fa782 SR |
1263 | bpage = list_entry(p, struct buffer_page, list); |
1264 | list_del_init(&bpage->list); | |
1265 | free_buffer_page(bpage); | |
7a8e76a3 | 1266 | } |
3adc54fa | 1267 | if (RB_WARN_ON(cpu_buffer, list_empty(cpu_buffer->pages))) |
292f60c0 | 1268 | goto out; |
7a8e76a3 SR |
1269 | |
1270 | rb_reset_cpu(cpu_buffer); | |
7a8e76a3 SR |
1271 | rb_check_pages(cpu_buffer); |
1272 | ||
292f60c0 | 1273 | out: |
dd7f5943 | 1274 | spin_unlock_irq(&cpu_buffer->reader_lock); |
7a8e76a3 SR |
1275 | } |
1276 | ||
1277 | static void | |
1278 | rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer, | |
1279 | struct list_head *pages, unsigned nr_pages) | |
1280 | { | |
044fa782 | 1281 | struct buffer_page *bpage; |
7a8e76a3 SR |
1282 | struct list_head *p; |
1283 | unsigned i; | |
1284 | ||
77ae365e SR |
1285 | spin_lock_irq(&cpu_buffer->reader_lock); |
1286 | rb_head_page_deactivate(cpu_buffer); | |
1287 | ||
7a8e76a3 | 1288 | for (i = 0; i < nr_pages; i++) { |
3e89c7bb | 1289 | if (RB_WARN_ON(cpu_buffer, list_empty(pages))) |
292f60c0 | 1290 | goto out; |
7a8e76a3 | 1291 | p = pages->next; |
044fa782 SR |
1292 | bpage = list_entry(p, struct buffer_page, list); |
1293 | list_del_init(&bpage->list); | |
3adc54fa | 1294 | list_add_tail(&bpage->list, cpu_buffer->pages); |
7a8e76a3 SR |
1295 | } |
1296 | rb_reset_cpu(cpu_buffer); | |
7a8e76a3 SR |
1297 | rb_check_pages(cpu_buffer); |
1298 | ||
292f60c0 | 1299 | out: |
dd7f5943 | 1300 | spin_unlock_irq(&cpu_buffer->reader_lock); |
7a8e76a3 SR |
1301 | } |
1302 | ||
1303 | /** | |
1304 | * ring_buffer_resize - resize the ring buffer | |
1305 | * @buffer: the buffer to resize. | |
1306 | * @size: the new size. | |
1307 | * | |
7a8e76a3 SR |
1308 | * Minimum size is 2 * BUF_PAGE_SIZE. |
1309 | * | |
1310 | * Returns -1 on failure. | |
1311 | */ | |
1312 | int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size) | |
1313 | { | |
1314 | struct ring_buffer_per_cpu *cpu_buffer; | |
1315 | unsigned nr_pages, rm_pages, new_pages; | |
044fa782 | 1316 | struct buffer_page *bpage, *tmp; |
7a8e76a3 SR |
1317 | unsigned long buffer_size; |
1318 | unsigned long addr; | |
1319 | LIST_HEAD(pages); | |
1320 | int i, cpu; | |
1321 | ||
ee51a1de IM |
1322 | /* |
1323 | * Always succeed at resizing a non-existent buffer: | |
1324 | */ | |
1325 | if (!buffer) | |
1326 | return size; | |
1327 | ||
7a8e76a3 SR |
1328 | size = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
1329 | size *= BUF_PAGE_SIZE; | |
1330 | buffer_size = buffer->pages * BUF_PAGE_SIZE; | |
1331 | ||
1332 | /* we need a minimum of two pages */ | |
1333 | if (size < BUF_PAGE_SIZE * 2) | |
1334 | size = BUF_PAGE_SIZE * 2; | |
1335 | ||
1336 | if (size == buffer_size) | |
1337 | return size; | |
1338 | ||
18421015 SR |
1339 | atomic_inc(&buffer->record_disabled); |
1340 | ||
1341 | /* Make sure all writers are done with this buffer. */ | |
1342 | synchronize_sched(); | |
1343 | ||
7a8e76a3 | 1344 | mutex_lock(&buffer->mutex); |
554f786e | 1345 | get_online_cpus(); |
7a8e76a3 SR |
1346 | |
1347 | nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); | |
1348 | ||
1349 | if (size < buffer_size) { | |
1350 | ||
1351 | /* easy case, just free pages */ | |
554f786e SR |
1352 | if (RB_WARN_ON(buffer, nr_pages >= buffer->pages)) |
1353 | goto out_fail; | |
7a8e76a3 SR |
1354 | |
1355 | rm_pages = buffer->pages - nr_pages; | |
1356 | ||
1357 | for_each_buffer_cpu(buffer, cpu) { | |
1358 | cpu_buffer = buffer->buffers[cpu]; | |
1359 | rb_remove_pages(cpu_buffer, rm_pages); | |
1360 | } | |
1361 | goto out; | |
1362 | } | |
1363 | ||
1364 | /* | |
1365 | * This is a bit more difficult. We only want to add pages | |
1366 | * when we can allocate enough for all CPUs. We do this | |
1367 | * by allocating all the pages and storing them on a local | |
1368 | * link list. If we succeed in our allocation, then we | |
1369 | * add these pages to the cpu_buffers. Otherwise we just free | |
1370 | * them all and return -ENOMEM; | |
1371 | */ | |
554f786e SR |
1372 | if (RB_WARN_ON(buffer, nr_pages <= buffer->pages)) |
1373 | goto out_fail; | |
f536aafc | 1374 | |
7a8e76a3 SR |
1375 | new_pages = nr_pages - buffer->pages; |
1376 | ||
1377 | for_each_buffer_cpu(buffer, cpu) { | |
1378 | for (i = 0; i < new_pages; i++) { | |
044fa782 | 1379 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), |
e4c2ce82 SR |
1380 | cache_line_size()), |
1381 | GFP_KERNEL, cpu_to_node(cpu)); | |
044fa782 | 1382 | if (!bpage) |
e4c2ce82 | 1383 | goto free_pages; |
044fa782 | 1384 | list_add(&bpage->list, &pages); |
7a8e76a3 SR |
1385 | addr = __get_free_page(GFP_KERNEL); |
1386 | if (!addr) | |
1387 | goto free_pages; | |
044fa782 SR |
1388 | bpage->page = (void *)addr; |
1389 | rb_init_page(bpage->page); | |
7a8e76a3 SR |
1390 | } |
1391 | } | |
1392 | ||
1393 | for_each_buffer_cpu(buffer, cpu) { | |
1394 | cpu_buffer = buffer->buffers[cpu]; | |
1395 | rb_insert_pages(cpu_buffer, &pages, new_pages); | |
1396 | } | |
1397 | ||
554f786e SR |
1398 | if (RB_WARN_ON(buffer, !list_empty(&pages))) |
1399 | goto out_fail; | |
7a8e76a3 SR |
1400 | |
1401 | out: | |
1402 | buffer->pages = nr_pages; | |
554f786e | 1403 | put_online_cpus(); |
7a8e76a3 SR |
1404 | mutex_unlock(&buffer->mutex); |
1405 | ||
18421015 SR |
1406 | atomic_dec(&buffer->record_disabled); |
1407 | ||
7a8e76a3 SR |
1408 | return size; |
1409 | ||
1410 | free_pages: | |
044fa782 SR |
1411 | list_for_each_entry_safe(bpage, tmp, &pages, list) { |
1412 | list_del_init(&bpage->list); | |
1413 | free_buffer_page(bpage); | |
7a8e76a3 | 1414 | } |
554f786e | 1415 | put_online_cpus(); |
641d2f63 | 1416 | mutex_unlock(&buffer->mutex); |
18421015 | 1417 | atomic_dec(&buffer->record_disabled); |
7a8e76a3 | 1418 | return -ENOMEM; |
554f786e SR |
1419 | |
1420 | /* | |
1421 | * Something went totally wrong, and we are too paranoid | |
1422 | * to even clean up the mess. | |
1423 | */ | |
1424 | out_fail: | |
1425 | put_online_cpus(); | |
1426 | mutex_unlock(&buffer->mutex); | |
18421015 | 1427 | atomic_dec(&buffer->record_disabled); |
554f786e | 1428 | return -1; |
7a8e76a3 | 1429 | } |
c4f50183 | 1430 | EXPORT_SYMBOL_GPL(ring_buffer_resize); |
7a8e76a3 | 1431 | |
8789a9e7 | 1432 | static inline void * |
044fa782 | 1433 | __rb_data_page_index(struct buffer_data_page *bpage, unsigned index) |
8789a9e7 | 1434 | { |
044fa782 | 1435 | return bpage->data + index; |
8789a9e7 SR |
1436 | } |
1437 | ||
044fa782 | 1438 | static inline void *__rb_page_index(struct buffer_page *bpage, unsigned index) |
7a8e76a3 | 1439 | { |
044fa782 | 1440 | return bpage->page->data + index; |
7a8e76a3 SR |
1441 | } |
1442 | ||
1443 | static inline struct ring_buffer_event * | |
d769041f | 1444 | rb_reader_event(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 1445 | { |
6f807acd SR |
1446 | return __rb_page_index(cpu_buffer->reader_page, |
1447 | cpu_buffer->reader_page->read); | |
1448 | } | |
1449 | ||
7a8e76a3 SR |
1450 | static inline struct ring_buffer_event * |
1451 | rb_iter_head_event(struct ring_buffer_iter *iter) | |
1452 | { | |
6f807acd | 1453 | return __rb_page_index(iter->head_page, iter->head); |
7a8e76a3 SR |
1454 | } |
1455 | ||
77ae365e | 1456 | static inline unsigned long rb_page_write(struct buffer_page *bpage) |
bf41a158 | 1457 | { |
77ae365e | 1458 | return local_read(&bpage->write) & RB_WRITE_MASK; |
bf41a158 SR |
1459 | } |
1460 | ||
1461 | static inline unsigned rb_page_commit(struct buffer_page *bpage) | |
1462 | { | |
abc9b56d | 1463 | return local_read(&bpage->page->commit); |
bf41a158 SR |
1464 | } |
1465 | ||
77ae365e SR |
1466 | static inline unsigned long rb_page_entries(struct buffer_page *bpage) |
1467 | { | |
1468 | return local_read(&bpage->entries) & RB_WRITE_MASK; | |
1469 | } | |
1470 | ||
bf41a158 SR |
1471 | /* Size is determined by what has been commited */ |
1472 | static inline unsigned rb_page_size(struct buffer_page *bpage) | |
1473 | { | |
1474 | return rb_page_commit(bpage); | |
1475 | } | |
1476 | ||
1477 | static inline unsigned | |
1478 | rb_commit_index(struct ring_buffer_per_cpu *cpu_buffer) | |
1479 | { | |
1480 | return rb_page_commit(cpu_buffer->commit_page); | |
1481 | } | |
1482 | ||
bf41a158 SR |
1483 | static inline unsigned |
1484 | rb_event_index(struct ring_buffer_event *event) | |
1485 | { | |
1486 | unsigned long addr = (unsigned long)event; | |
1487 | ||
22f470f8 | 1488 | return (addr & ~PAGE_MASK) - BUF_PAGE_HDR_SIZE; |
bf41a158 SR |
1489 | } |
1490 | ||
0f0c85fc | 1491 | static inline int |
fa743953 SR |
1492 | rb_event_is_commit(struct ring_buffer_per_cpu *cpu_buffer, |
1493 | struct ring_buffer_event *event) | |
bf41a158 SR |
1494 | { |
1495 | unsigned long addr = (unsigned long)event; | |
1496 | unsigned long index; | |
1497 | ||
1498 | index = rb_event_index(event); | |
1499 | addr &= PAGE_MASK; | |
1500 | ||
1501 | return cpu_buffer->commit_page->page == (void *)addr && | |
1502 | rb_commit_index(cpu_buffer) == index; | |
1503 | } | |
1504 | ||
34a148bf | 1505 | static void |
bf41a158 | 1506 | rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 1507 | { |
77ae365e SR |
1508 | unsigned long max_count; |
1509 | ||
bf41a158 SR |
1510 | /* |
1511 | * We only race with interrupts and NMIs on this CPU. | |
1512 | * If we own the commit event, then we can commit | |
1513 | * all others that interrupted us, since the interruptions | |
1514 | * are in stack format (they finish before they come | |
1515 | * back to us). This allows us to do a simple loop to | |
1516 | * assign the commit to the tail. | |
1517 | */ | |
a8ccf1d6 | 1518 | again: |
77ae365e SR |
1519 | max_count = cpu_buffer->buffer->pages * 100; |
1520 | ||
bf41a158 | 1521 | while (cpu_buffer->commit_page != cpu_buffer->tail_page) { |
77ae365e SR |
1522 | if (RB_WARN_ON(cpu_buffer, !(--max_count))) |
1523 | return; | |
1524 | if (RB_WARN_ON(cpu_buffer, | |
1525 | rb_is_reader_page(cpu_buffer->tail_page))) | |
1526 | return; | |
1527 | local_set(&cpu_buffer->commit_page->page->commit, | |
1528 | rb_page_write(cpu_buffer->commit_page)); | |
bf41a158 | 1529 | rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); |
abc9b56d SR |
1530 | cpu_buffer->write_stamp = |
1531 | cpu_buffer->commit_page->page->time_stamp; | |
bf41a158 SR |
1532 | /* add barrier to keep gcc from optimizing too much */ |
1533 | barrier(); | |
1534 | } | |
1535 | while (rb_commit_index(cpu_buffer) != | |
1536 | rb_page_write(cpu_buffer->commit_page)) { | |
77ae365e SR |
1537 | |
1538 | local_set(&cpu_buffer->commit_page->page->commit, | |
1539 | rb_page_write(cpu_buffer->commit_page)); | |
1540 | RB_WARN_ON(cpu_buffer, | |
1541 | local_read(&cpu_buffer->commit_page->page->commit) & | |
1542 | ~RB_WRITE_MASK); | |
bf41a158 SR |
1543 | barrier(); |
1544 | } | |
a8ccf1d6 SR |
1545 | |
1546 | /* again, keep gcc from optimizing */ | |
1547 | barrier(); | |
1548 | ||
1549 | /* | |
1550 | * If an interrupt came in just after the first while loop | |
1551 | * and pushed the tail page forward, we will be left with | |
1552 | * a dangling commit that will never go forward. | |
1553 | */ | |
1554 | if (unlikely(cpu_buffer->commit_page != cpu_buffer->tail_page)) | |
1555 | goto again; | |
7a8e76a3 SR |
1556 | } |
1557 | ||
d769041f | 1558 | static void rb_reset_reader_page(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 1559 | { |
abc9b56d | 1560 | cpu_buffer->read_stamp = cpu_buffer->reader_page->page->time_stamp; |
6f807acd | 1561 | cpu_buffer->reader_page->read = 0; |
d769041f SR |
1562 | } |
1563 | ||
34a148bf | 1564 | static void rb_inc_iter(struct ring_buffer_iter *iter) |
d769041f SR |
1565 | { |
1566 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
1567 | ||
1568 | /* | |
1569 | * The iterator could be on the reader page (it starts there). | |
1570 | * But the head could have moved, since the reader was | |
1571 | * found. Check for this case and assign the iterator | |
1572 | * to the head page instead of next. | |
1573 | */ | |
1574 | if (iter->head_page == cpu_buffer->reader_page) | |
77ae365e | 1575 | iter->head_page = rb_set_head_page(cpu_buffer); |
d769041f SR |
1576 | else |
1577 | rb_inc_page(cpu_buffer, &iter->head_page); | |
1578 | ||
abc9b56d | 1579 | iter->read_stamp = iter->head_page->page->time_stamp; |
7a8e76a3 SR |
1580 | iter->head = 0; |
1581 | } | |
1582 | ||
69d1b839 SR |
1583 | /* Slow path, do not inline */ |
1584 | static noinline struct ring_buffer_event * | |
1585 | rb_add_time_stamp(struct ring_buffer_event *event, u64 delta) | |
1586 | { | |
1587 | event->type_len = RINGBUF_TYPE_TIME_EXTEND; | |
1588 | ||
1589 | /* Not the first event on the page? */ | |
1590 | if (rb_event_index(event)) { | |
1591 | event->time_delta = delta & TS_MASK; | |
1592 | event->array[0] = delta >> TS_SHIFT; | |
1593 | } else { | |
1594 | /* nope, just zero it */ | |
1595 | event->time_delta = 0; | |
1596 | event->array[0] = 0; | |
1597 | } | |
1598 | ||
1599 | return skip_time_extend(event); | |
1600 | } | |
1601 | ||
7a8e76a3 SR |
1602 | /** |
1603 | * ring_buffer_update_event - update event type and data | |
1604 | * @event: the even to update | |
1605 | * @type: the type of event | |
1606 | * @length: the size of the event field in the ring buffer | |
1607 | * | |
1608 | * Update the type and data fields of the event. The length | |
1609 | * is the actual size that is written to the ring buffer, | |
1610 | * and with this, we can determine what to place into the | |
1611 | * data field. | |
1612 | */ | |
34a148bf | 1613 | static void |
69d1b839 SR |
1614 | rb_update_event(struct ring_buffer_per_cpu *cpu_buffer, |
1615 | struct ring_buffer_event *event, unsigned length, | |
1616 | int add_timestamp, u64 delta) | |
7a8e76a3 | 1617 | { |
69d1b839 SR |
1618 | /* Only a commit updates the timestamp */ |
1619 | if (unlikely(!rb_event_is_commit(cpu_buffer, event))) | |
1620 | delta = 0; | |
7a8e76a3 | 1621 | |
69d1b839 SR |
1622 | /* |
1623 | * If we need to add a timestamp, then we | |
1624 | * add it to the start of the resevered space. | |
1625 | */ | |
1626 | if (unlikely(add_timestamp)) { | |
1627 | event = rb_add_time_stamp(event, delta); | |
1628 | length -= RB_LEN_TIME_EXTEND; | |
1629 | delta = 0; | |
7a8e76a3 | 1630 | } |
69d1b839 SR |
1631 | |
1632 | event->time_delta = delta; | |
1633 | length -= RB_EVNT_HDR_SIZE; | |
1634 | if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) { | |
1635 | event->type_len = 0; | |
1636 | event->array[0] = length; | |
1637 | } else | |
1638 | event->type_len = DIV_ROUND_UP(length, RB_ALIGNMENT); | |
7a8e76a3 SR |
1639 | } |
1640 | ||
77ae365e SR |
1641 | /* |
1642 | * rb_handle_head_page - writer hit the head page | |
1643 | * | |
1644 | * Returns: +1 to retry page | |
1645 | * 0 to continue | |
1646 | * -1 on error | |
1647 | */ | |
1648 | static int | |
1649 | rb_handle_head_page(struct ring_buffer_per_cpu *cpu_buffer, | |
1650 | struct buffer_page *tail_page, | |
1651 | struct buffer_page *next_page) | |
1652 | { | |
1653 | struct buffer_page *new_head; | |
1654 | int entries; | |
1655 | int type; | |
1656 | int ret; | |
1657 | ||
1658 | entries = rb_page_entries(next_page); | |
1659 | ||
1660 | /* | |
1661 | * The hard part is here. We need to move the head | |
1662 | * forward, and protect against both readers on | |
1663 | * other CPUs and writers coming in via interrupts. | |
1664 | */ | |
1665 | type = rb_head_page_set_update(cpu_buffer, next_page, tail_page, | |
1666 | RB_PAGE_HEAD); | |
1667 | ||
1668 | /* | |
1669 | * type can be one of four: | |
1670 | * NORMAL - an interrupt already moved it for us | |
1671 | * HEAD - we are the first to get here. | |
1672 | * UPDATE - we are the interrupt interrupting | |
1673 | * a current move. | |
1674 | * MOVED - a reader on another CPU moved the next | |
1675 | * pointer to its reader page. Give up | |
1676 | * and try again. | |
1677 | */ | |
1678 | ||
1679 | switch (type) { | |
1680 | case RB_PAGE_HEAD: | |
1681 | /* | |
1682 | * We changed the head to UPDATE, thus | |
1683 | * it is our responsibility to update | |
1684 | * the counters. | |
1685 | */ | |
1686 | local_add(entries, &cpu_buffer->overrun); | |
1687 | ||
1688 | /* | |
1689 | * The entries will be zeroed out when we move the | |
1690 | * tail page. | |
1691 | */ | |
1692 | ||
1693 | /* still more to do */ | |
1694 | break; | |
1695 | ||
1696 | case RB_PAGE_UPDATE: | |
1697 | /* | |
1698 | * This is an interrupt that interrupt the | |
1699 | * previous update. Still more to do. | |
1700 | */ | |
1701 | break; | |
1702 | case RB_PAGE_NORMAL: | |
1703 | /* | |
1704 | * An interrupt came in before the update | |
1705 | * and processed this for us. | |
1706 | * Nothing left to do. | |
1707 | */ | |
1708 | return 1; | |
1709 | case RB_PAGE_MOVED: | |
1710 | /* | |
1711 | * The reader is on another CPU and just did | |
1712 | * a swap with our next_page. | |
1713 | * Try again. | |
1714 | */ | |
1715 | return 1; | |
1716 | default: | |
1717 | RB_WARN_ON(cpu_buffer, 1); /* WTF??? */ | |
1718 | return -1; | |
1719 | } | |
1720 | ||
1721 | /* | |
1722 | * Now that we are here, the old head pointer is | |
1723 | * set to UPDATE. This will keep the reader from | |
1724 | * swapping the head page with the reader page. | |
1725 | * The reader (on another CPU) will spin till | |
1726 | * we are finished. | |
1727 | * | |
1728 | * We just need to protect against interrupts | |
1729 | * doing the job. We will set the next pointer | |
1730 | * to HEAD. After that, we set the old pointer | |
1731 | * to NORMAL, but only if it was HEAD before. | |
1732 | * otherwise we are an interrupt, and only | |
1733 | * want the outer most commit to reset it. | |
1734 | */ | |
1735 | new_head = next_page; | |
1736 | rb_inc_page(cpu_buffer, &new_head); | |
1737 | ||
1738 | ret = rb_head_page_set_head(cpu_buffer, new_head, next_page, | |
1739 | RB_PAGE_NORMAL); | |
1740 | ||
1741 | /* | |
1742 | * Valid returns are: | |
1743 | * HEAD - an interrupt came in and already set it. | |
1744 | * NORMAL - One of two things: | |
1745 | * 1) We really set it. | |
1746 | * 2) A bunch of interrupts came in and moved | |
1747 | * the page forward again. | |
1748 | */ | |
1749 | switch (ret) { | |
1750 | case RB_PAGE_HEAD: | |
1751 | case RB_PAGE_NORMAL: | |
1752 | /* OK */ | |
1753 | break; | |
1754 | default: | |
1755 | RB_WARN_ON(cpu_buffer, 1); | |
1756 | return -1; | |
1757 | } | |
1758 | ||
1759 | /* | |
1760 | * It is possible that an interrupt came in, | |
1761 | * set the head up, then more interrupts came in | |
1762 | * and moved it again. When we get back here, | |
1763 | * the page would have been set to NORMAL but we | |
1764 | * just set it back to HEAD. | |
1765 | * | |
1766 | * How do you detect this? Well, if that happened | |
1767 | * the tail page would have moved. | |
1768 | */ | |
1769 | if (ret == RB_PAGE_NORMAL) { | |
1770 | /* | |
1771 | * If the tail had moved passed next, then we need | |
1772 | * to reset the pointer. | |
1773 | */ | |
1774 | if (cpu_buffer->tail_page != tail_page && | |
1775 | cpu_buffer->tail_page != next_page) | |
1776 | rb_head_page_set_normal(cpu_buffer, new_head, | |
1777 | next_page, | |
1778 | RB_PAGE_HEAD); | |
1779 | } | |
1780 | ||
1781 | /* | |
1782 | * If this was the outer most commit (the one that | |
1783 | * changed the original pointer from HEAD to UPDATE), | |
1784 | * then it is up to us to reset it to NORMAL. | |
1785 | */ | |
1786 | if (type == RB_PAGE_HEAD) { | |
1787 | ret = rb_head_page_set_normal(cpu_buffer, next_page, | |
1788 | tail_page, | |
1789 | RB_PAGE_UPDATE); | |
1790 | if (RB_WARN_ON(cpu_buffer, | |
1791 | ret != RB_PAGE_UPDATE)) | |
1792 | return -1; | |
1793 | } | |
1794 | ||
1795 | return 0; | |
1796 | } | |
1797 | ||
34a148bf | 1798 | static unsigned rb_calculate_event_length(unsigned length) |
7a8e76a3 SR |
1799 | { |
1800 | struct ring_buffer_event event; /* Used only for sizeof array */ | |
1801 | ||
1802 | /* zero length can cause confusions */ | |
1803 | if (!length) | |
1804 | length = 1; | |
1805 | ||
2271048d | 1806 | if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) |
7a8e76a3 SR |
1807 | length += sizeof(event.array[0]); |
1808 | ||
1809 | length += RB_EVNT_HDR_SIZE; | |
2271048d | 1810 | length = ALIGN(length, RB_ARCH_ALIGNMENT); |
7a8e76a3 SR |
1811 | |
1812 | return length; | |
1813 | } | |
1814 | ||
c7b09308 SR |
1815 | static inline void |
1816 | rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer, | |
1817 | struct buffer_page *tail_page, | |
1818 | unsigned long tail, unsigned long length) | |
1819 | { | |
1820 | struct ring_buffer_event *event; | |
1821 | ||
1822 | /* | |
1823 | * Only the event that crossed the page boundary | |
1824 | * must fill the old tail_page with padding. | |
1825 | */ | |
1826 | if (tail >= BUF_PAGE_SIZE) { | |
b3230c8b SR |
1827 | /* |
1828 | * If the page was filled, then we still need | |
1829 | * to update the real_end. Reset it to zero | |
1830 | * and the reader will ignore it. | |
1831 | */ | |
1832 | if (tail == BUF_PAGE_SIZE) | |
1833 | tail_page->real_end = 0; | |
1834 | ||
c7b09308 SR |
1835 | local_sub(length, &tail_page->write); |
1836 | return; | |
1837 | } | |
1838 | ||
1839 | event = __rb_page_index(tail_page, tail); | |
b0b7065b | 1840 | kmemcheck_annotate_bitfield(event, bitfield); |
c7b09308 | 1841 | |
ff0ff84a SR |
1842 | /* |
1843 | * Save the original length to the meta data. | |
1844 | * This will be used by the reader to add lost event | |
1845 | * counter. | |
1846 | */ | |
1847 | tail_page->real_end = tail; | |
1848 | ||
c7b09308 SR |
1849 | /* |
1850 | * If this event is bigger than the minimum size, then | |
1851 | * we need to be careful that we don't subtract the | |
1852 | * write counter enough to allow another writer to slip | |
1853 | * in on this page. | |
1854 | * We put in a discarded commit instead, to make sure | |
1855 | * that this space is not used again. | |
1856 | * | |
1857 | * If we are less than the minimum size, we don't need to | |
1858 | * worry about it. | |
1859 | */ | |
1860 | if (tail > (BUF_PAGE_SIZE - RB_EVNT_MIN_SIZE)) { | |
1861 | /* No room for any events */ | |
1862 | ||
1863 | /* Mark the rest of the page with padding */ | |
1864 | rb_event_set_padding(event); | |
1865 | ||
1866 | /* Set the write back to the previous setting */ | |
1867 | local_sub(length, &tail_page->write); | |
1868 | return; | |
1869 | } | |
1870 | ||
1871 | /* Put in a discarded event */ | |
1872 | event->array[0] = (BUF_PAGE_SIZE - tail) - RB_EVNT_HDR_SIZE; | |
1873 | event->type_len = RINGBUF_TYPE_PADDING; | |
1874 | /* time delta must be non zero */ | |
1875 | event->time_delta = 1; | |
c7b09308 SR |
1876 | |
1877 | /* Set write to end of buffer */ | |
1878 | length = (tail + length) - BUF_PAGE_SIZE; | |
1879 | local_sub(length, &tail_page->write); | |
1880 | } | |
6634ff26 | 1881 | |
747e94ae SR |
1882 | /* |
1883 | * This is the slow path, force gcc not to inline it. | |
1884 | */ | |
1885 | static noinline struct ring_buffer_event * | |
6634ff26 SR |
1886 | rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer, |
1887 | unsigned long length, unsigned long tail, | |
e8bc43e8 | 1888 | struct buffer_page *tail_page, u64 ts) |
7a8e76a3 | 1889 | { |
5a50e33c | 1890 | struct buffer_page *commit_page = cpu_buffer->commit_page; |
7a8e76a3 | 1891 | struct ring_buffer *buffer = cpu_buffer->buffer; |
77ae365e SR |
1892 | struct buffer_page *next_page; |
1893 | int ret; | |
aa20ae84 SR |
1894 | |
1895 | next_page = tail_page; | |
1896 | ||
aa20ae84 SR |
1897 | rb_inc_page(cpu_buffer, &next_page); |
1898 | ||
aa20ae84 SR |
1899 | /* |
1900 | * If for some reason, we had an interrupt storm that made | |
1901 | * it all the way around the buffer, bail, and warn | |
1902 | * about it. | |
1903 | */ | |
1904 | if (unlikely(next_page == commit_page)) { | |
77ae365e | 1905 | local_inc(&cpu_buffer->commit_overrun); |
aa20ae84 SR |
1906 | goto out_reset; |
1907 | } | |
1908 | ||
77ae365e SR |
1909 | /* |
1910 | * This is where the fun begins! | |
1911 | * | |
1912 | * We are fighting against races between a reader that | |
1913 | * could be on another CPU trying to swap its reader | |
1914 | * page with the buffer head. | |
1915 | * | |
1916 | * We are also fighting against interrupts coming in and | |
1917 | * moving the head or tail on us as well. | |
1918 | * | |
1919 | * If the next page is the head page then we have filled | |
1920 | * the buffer, unless the commit page is still on the | |
1921 | * reader page. | |
1922 | */ | |
1923 | if (rb_is_head_page(cpu_buffer, next_page, &tail_page->list)) { | |
aa20ae84 | 1924 | |
77ae365e SR |
1925 | /* |
1926 | * If the commit is not on the reader page, then | |
1927 | * move the header page. | |
1928 | */ | |
1929 | if (!rb_is_reader_page(cpu_buffer->commit_page)) { | |
1930 | /* | |
1931 | * If we are not in overwrite mode, | |
1932 | * this is easy, just stop here. | |
1933 | */ | |
1934 | if (!(buffer->flags & RB_FL_OVERWRITE)) | |
1935 | goto out_reset; | |
1936 | ||
1937 | ret = rb_handle_head_page(cpu_buffer, | |
1938 | tail_page, | |
1939 | next_page); | |
1940 | if (ret < 0) | |
1941 | goto out_reset; | |
1942 | if (ret) | |
1943 | goto out_again; | |
1944 | } else { | |
1945 | /* | |
1946 | * We need to be careful here too. The | |
1947 | * commit page could still be on the reader | |
1948 | * page. We could have a small buffer, and | |
1949 | * have filled up the buffer with events | |
1950 | * from interrupts and such, and wrapped. | |
1951 | * | |
1952 | * Note, if the tail page is also the on the | |
1953 | * reader_page, we let it move out. | |
1954 | */ | |
1955 | if (unlikely((cpu_buffer->commit_page != | |
1956 | cpu_buffer->tail_page) && | |
1957 | (cpu_buffer->commit_page == | |
1958 | cpu_buffer->reader_page))) { | |
1959 | local_inc(&cpu_buffer->commit_overrun); | |
1960 | goto out_reset; | |
1961 | } | |
aa20ae84 SR |
1962 | } |
1963 | } | |
1964 | ||
77ae365e SR |
1965 | ret = rb_tail_page_update(cpu_buffer, tail_page, next_page); |
1966 | if (ret) { | |
1967 | /* | |
1968 | * Nested commits always have zero deltas, so | |
1969 | * just reread the time stamp | |
1970 | */ | |
e8bc43e8 SR |
1971 | ts = rb_time_stamp(buffer); |
1972 | next_page->page->time_stamp = ts; | |
aa20ae84 SR |
1973 | } |
1974 | ||
77ae365e | 1975 | out_again: |
aa20ae84 | 1976 | |
77ae365e | 1977 | rb_reset_tail(cpu_buffer, tail_page, tail, length); |
aa20ae84 SR |
1978 | |
1979 | /* fail and let the caller try again */ | |
1980 | return ERR_PTR(-EAGAIN); | |
1981 | ||
45141d46 | 1982 | out_reset: |
6f3b3440 | 1983 | /* reset write */ |
c7b09308 | 1984 | rb_reset_tail(cpu_buffer, tail_page, tail, length); |
6f3b3440 | 1985 | |
bf41a158 | 1986 | return NULL; |
7a8e76a3 SR |
1987 | } |
1988 | ||
6634ff26 SR |
1989 | static struct ring_buffer_event * |
1990 | __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, | |
69d1b839 SR |
1991 | unsigned long length, u64 ts, |
1992 | u64 delta, int add_timestamp) | |
6634ff26 | 1993 | { |
5a50e33c | 1994 | struct buffer_page *tail_page; |
6634ff26 SR |
1995 | struct ring_buffer_event *event; |
1996 | unsigned long tail, write; | |
1997 | ||
69d1b839 SR |
1998 | /* |
1999 | * If the time delta since the last event is too big to | |
2000 | * hold in the time field of the event, then we append a | |
2001 | * TIME EXTEND event ahead of the data event. | |
2002 | */ | |
2003 | if (unlikely(add_timestamp)) | |
2004 | length += RB_LEN_TIME_EXTEND; | |
2005 | ||
6634ff26 SR |
2006 | tail_page = cpu_buffer->tail_page; |
2007 | write = local_add_return(length, &tail_page->write); | |
77ae365e SR |
2008 | |
2009 | /* set write to only the index of the write */ | |
2010 | write &= RB_WRITE_MASK; | |
6634ff26 SR |
2011 | tail = write - length; |
2012 | ||
2013 | /* See if we shot pass the end of this buffer page */ | |
747e94ae | 2014 | if (unlikely(write > BUF_PAGE_SIZE)) |
6634ff26 | 2015 | return rb_move_tail(cpu_buffer, length, tail, |
5a50e33c | 2016 | tail_page, ts); |
6634ff26 SR |
2017 | |
2018 | /* We reserved something on the buffer */ | |
2019 | ||
6634ff26 | 2020 | event = __rb_page_index(tail_page, tail); |
1744a21d | 2021 | kmemcheck_annotate_bitfield(event, bitfield); |
69d1b839 | 2022 | rb_update_event(cpu_buffer, event, length, add_timestamp, delta); |
6634ff26 | 2023 | |
69d1b839 | 2024 | local_inc(&tail_page->entries); |
6634ff26 SR |
2025 | |
2026 | /* | |
fa743953 SR |
2027 | * If this is the first commit on the page, then update |
2028 | * its timestamp. | |
6634ff26 | 2029 | */ |
fa743953 | 2030 | if (!tail) |
e8bc43e8 | 2031 | tail_page->page->time_stamp = ts; |
6634ff26 SR |
2032 | |
2033 | return event; | |
2034 | } | |
2035 | ||
edd813bf SR |
2036 | static inline int |
2037 | rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer, | |
2038 | struct ring_buffer_event *event) | |
2039 | { | |
2040 | unsigned long new_index, old_index; | |
2041 | struct buffer_page *bpage; | |
2042 | unsigned long index; | |
2043 | unsigned long addr; | |
2044 | ||
2045 | new_index = rb_event_index(event); | |
69d1b839 | 2046 | old_index = new_index + rb_event_ts_length(event); |
edd813bf SR |
2047 | addr = (unsigned long)event; |
2048 | addr &= PAGE_MASK; | |
2049 | ||
2050 | bpage = cpu_buffer->tail_page; | |
2051 | ||
2052 | if (bpage->page == (void *)addr && rb_page_write(bpage) == old_index) { | |
77ae365e SR |
2053 | unsigned long write_mask = |
2054 | local_read(&bpage->write) & ~RB_WRITE_MASK; | |
edd813bf SR |
2055 | /* |
2056 | * This is on the tail page. It is possible that | |
2057 | * a write could come in and move the tail page | |
2058 | * and write to the next page. That is fine | |
2059 | * because we just shorten what is on this page. | |
2060 | */ | |
77ae365e SR |
2061 | old_index += write_mask; |
2062 | new_index += write_mask; | |
edd813bf SR |
2063 | index = local_cmpxchg(&bpage->write, old_index, new_index); |
2064 | if (index == old_index) | |
2065 | return 1; | |
2066 | } | |
2067 | ||
2068 | /* could not discard */ | |
2069 | return 0; | |
2070 | } | |
2071 | ||
fa743953 SR |
2072 | static void rb_start_commit(struct ring_buffer_per_cpu *cpu_buffer) |
2073 | { | |
2074 | local_inc(&cpu_buffer->committing); | |
2075 | local_inc(&cpu_buffer->commits); | |
2076 | } | |
2077 | ||
d9abde21 | 2078 | static inline void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer) |
fa743953 SR |
2079 | { |
2080 | unsigned long commits; | |
2081 | ||
2082 | if (RB_WARN_ON(cpu_buffer, | |
2083 | !local_read(&cpu_buffer->committing))) | |
2084 | return; | |
2085 | ||
2086 | again: | |
2087 | commits = local_read(&cpu_buffer->commits); | |
2088 | /* synchronize with interrupts */ | |
2089 | barrier(); | |
2090 | if (local_read(&cpu_buffer->committing) == 1) | |
2091 | rb_set_commit_to_write(cpu_buffer); | |
2092 | ||
2093 | local_dec(&cpu_buffer->committing); | |
2094 | ||
2095 | /* synchronize with interrupts */ | |
2096 | barrier(); | |
2097 | ||
2098 | /* | |
2099 | * Need to account for interrupts coming in between the | |
2100 | * updating of the commit page and the clearing of the | |
2101 | * committing counter. | |
2102 | */ | |
2103 | if (unlikely(local_read(&cpu_buffer->commits) != commits) && | |
2104 | !local_read(&cpu_buffer->committing)) { | |
2105 | local_inc(&cpu_buffer->committing); | |
2106 | goto again; | |
2107 | } | |
2108 | } | |
2109 | ||
7a8e76a3 | 2110 | static struct ring_buffer_event * |
62f0b3eb SR |
2111 | rb_reserve_next_event(struct ring_buffer *buffer, |
2112 | struct ring_buffer_per_cpu *cpu_buffer, | |
1cd8d735 | 2113 | unsigned long length) |
7a8e76a3 SR |
2114 | { |
2115 | struct ring_buffer_event *event; | |
69d1b839 | 2116 | u64 ts, delta; |
818e3dd3 | 2117 | int nr_loops = 0; |
69d1b839 | 2118 | int add_timestamp; |
140ff891 | 2119 | u64 diff; |
7a8e76a3 | 2120 | |
fa743953 SR |
2121 | rb_start_commit(cpu_buffer); |
2122 | ||
85bac32c | 2123 | #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP |
62f0b3eb SR |
2124 | /* |
2125 | * Due to the ability to swap a cpu buffer from a buffer | |
2126 | * it is possible it was swapped before we committed. | |
2127 | * (committing stops a swap). We check for it here and | |
2128 | * if it happened, we have to fail the write. | |
2129 | */ | |
2130 | barrier(); | |
2131 | if (unlikely(ACCESS_ONCE(cpu_buffer->buffer) != buffer)) { | |
2132 | local_dec(&cpu_buffer->committing); | |
2133 | local_dec(&cpu_buffer->commits); | |
2134 | return NULL; | |
2135 | } | |
85bac32c | 2136 | #endif |
62f0b3eb | 2137 | |
be957c44 | 2138 | length = rb_calculate_event_length(length); |
bf41a158 | 2139 | again: |
69d1b839 SR |
2140 | add_timestamp = 0; |
2141 | delta = 0; | |
2142 | ||
818e3dd3 SR |
2143 | /* |
2144 | * We allow for interrupts to reenter here and do a trace. | |
2145 | * If one does, it will cause this original code to loop | |
2146 | * back here. Even with heavy interrupts happening, this | |
2147 | * should only happen a few times in a row. If this happens | |
2148 | * 1000 times in a row, there must be either an interrupt | |
2149 | * storm or we have something buggy. | |
2150 | * Bail! | |
2151 | */ | |
3e89c7bb | 2152 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000)) |
fa743953 | 2153 | goto out_fail; |
818e3dd3 | 2154 | |
6d3f1e12 | 2155 | ts = rb_time_stamp(cpu_buffer->buffer); |
140ff891 | 2156 | diff = ts - cpu_buffer->write_stamp; |
7a8e76a3 | 2157 | |
140ff891 SR |
2158 | /* make sure this diff is calculated here */ |
2159 | barrier(); | |
bf41a158 | 2160 | |
140ff891 SR |
2161 | /* Did the write stamp get updated already? */ |
2162 | if (likely(ts >= cpu_buffer->write_stamp)) { | |
168b6b1d SR |
2163 | delta = diff; |
2164 | if (unlikely(test_time_stamp(delta))) { | |
69d1b839 | 2165 | WARN_ONCE(delta > (1ULL << 59), |
e9345aab | 2166 | KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n", |
69d1b839 SR |
2167 | (unsigned long long)delta, |
2168 | (unsigned long long)ts, | |
e9345aab | 2169 | (unsigned long long)cpu_buffer->write_stamp); |
69d1b839 | 2170 | add_timestamp = 1; |
7a8e76a3 | 2171 | } |
168b6b1d | 2172 | } |
7a8e76a3 | 2173 | |
69d1b839 SR |
2174 | event = __rb_reserve_next(cpu_buffer, length, ts, |
2175 | delta, add_timestamp); | |
168b6b1d | 2176 | if (unlikely(PTR_ERR(event) == -EAGAIN)) |
bf41a158 SR |
2177 | goto again; |
2178 | ||
fa743953 SR |
2179 | if (!event) |
2180 | goto out_fail; | |
7a8e76a3 | 2181 | |
7a8e76a3 | 2182 | return event; |
fa743953 SR |
2183 | |
2184 | out_fail: | |
2185 | rb_end_commit(cpu_buffer); | |
2186 | return NULL; | |
7a8e76a3 SR |
2187 | } |
2188 | ||
1155de47 PM |
2189 | #ifdef CONFIG_TRACING |
2190 | ||
aa18efb2 | 2191 | #define TRACE_RECURSIVE_DEPTH 16 |
261842b7 | 2192 | |
d9abde21 SR |
2193 | /* Keep this code out of the fast path cache */ |
2194 | static noinline void trace_recursive_fail(void) | |
261842b7 | 2195 | { |
aa18efb2 SR |
2196 | /* Disable all tracing before we do anything else */ |
2197 | tracing_off_permanent(); | |
261842b7 | 2198 | |
7d7d2b80 | 2199 | printk_once(KERN_WARNING "Tracing recursion: depth[%ld]:" |
aa18efb2 SR |
2200 | "HC[%lu]:SC[%lu]:NMI[%lu]\n", |
2201 | current->trace_recursion, | |
2202 | hardirq_count() >> HARDIRQ_SHIFT, | |
2203 | softirq_count() >> SOFTIRQ_SHIFT, | |
2204 | in_nmi()); | |
261842b7 | 2205 | |
aa18efb2 | 2206 | WARN_ON_ONCE(1); |
d9abde21 SR |
2207 | } |
2208 | ||
2209 | static inline int trace_recursive_lock(void) | |
2210 | { | |
2211 | current->trace_recursion++; | |
2212 | ||
2213 | if (likely(current->trace_recursion < TRACE_RECURSIVE_DEPTH)) | |
2214 | return 0; | |
2215 | ||
2216 | trace_recursive_fail(); | |
2217 | ||
aa18efb2 | 2218 | return -1; |
261842b7 SR |
2219 | } |
2220 | ||
d9abde21 | 2221 | static inline void trace_recursive_unlock(void) |
261842b7 | 2222 | { |
aa18efb2 | 2223 | WARN_ON_ONCE(!current->trace_recursion); |
261842b7 | 2224 | |
aa18efb2 | 2225 | current->trace_recursion--; |
261842b7 SR |
2226 | } |
2227 | ||
1155de47 PM |
2228 | #else |
2229 | ||
2230 | #define trace_recursive_lock() (0) | |
2231 | #define trace_recursive_unlock() do { } while (0) | |
2232 | ||
2233 | #endif | |
2234 | ||
7a8e76a3 SR |
2235 | /** |
2236 | * ring_buffer_lock_reserve - reserve a part of the buffer | |
2237 | * @buffer: the ring buffer to reserve from | |
2238 | * @length: the length of the data to reserve (excluding event header) | |
7a8e76a3 SR |
2239 | * |
2240 | * Returns a reseverd event on the ring buffer to copy directly to. | |
2241 | * The user of this interface will need to get the body to write into | |
2242 | * and can use the ring_buffer_event_data() interface. | |
2243 | * | |
2244 | * The length is the length of the data needed, not the event length | |
2245 | * which also includes the event header. | |
2246 | * | |
2247 | * Must be paired with ring_buffer_unlock_commit, unless NULL is returned. | |
2248 | * If NULL is returned, then nothing has been allocated or locked. | |
2249 | */ | |
2250 | struct ring_buffer_event * | |
0a987751 | 2251 | ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length) |
7a8e76a3 SR |
2252 | { |
2253 | struct ring_buffer_per_cpu *cpu_buffer; | |
2254 | struct ring_buffer_event *event; | |
5168ae50 | 2255 | int cpu; |
7a8e76a3 | 2256 | |
033601a3 | 2257 | if (ring_buffer_flags != RB_BUFFERS_ON) |
a3583244 SR |
2258 | return NULL; |
2259 | ||
bf41a158 | 2260 | /* If we are tracing schedule, we don't want to recurse */ |
5168ae50 | 2261 | preempt_disable_notrace(); |
bf41a158 | 2262 | |
52fbe9cd LJ |
2263 | if (atomic_read(&buffer->record_disabled)) |
2264 | goto out_nocheck; | |
2265 | ||
261842b7 SR |
2266 | if (trace_recursive_lock()) |
2267 | goto out_nocheck; | |
2268 | ||
7a8e76a3 SR |
2269 | cpu = raw_smp_processor_id(); |
2270 | ||
9e01c1b7 | 2271 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
d769041f | 2272 | goto out; |
7a8e76a3 SR |
2273 | |
2274 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 SR |
2275 | |
2276 | if (atomic_read(&cpu_buffer->record_disabled)) | |
d769041f | 2277 | goto out; |
7a8e76a3 | 2278 | |
be957c44 | 2279 | if (length > BUF_MAX_DATA_SIZE) |
bf41a158 | 2280 | goto out; |
7a8e76a3 | 2281 | |
62f0b3eb | 2282 | event = rb_reserve_next_event(buffer, cpu_buffer, length); |
7a8e76a3 | 2283 | if (!event) |
d769041f | 2284 | goto out; |
7a8e76a3 SR |
2285 | |
2286 | return event; | |
2287 | ||
d769041f | 2288 | out: |
261842b7 SR |
2289 | trace_recursive_unlock(); |
2290 | ||
2291 | out_nocheck: | |
5168ae50 | 2292 | preempt_enable_notrace(); |
7a8e76a3 SR |
2293 | return NULL; |
2294 | } | |
c4f50183 | 2295 | EXPORT_SYMBOL_GPL(ring_buffer_lock_reserve); |
7a8e76a3 | 2296 | |
a1863c21 SR |
2297 | static void |
2298 | rb_update_write_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
7a8e76a3 SR |
2299 | struct ring_buffer_event *event) |
2300 | { | |
69d1b839 SR |
2301 | u64 delta; |
2302 | ||
fa743953 SR |
2303 | /* |
2304 | * The event first in the commit queue updates the | |
2305 | * time stamp. | |
2306 | */ | |
69d1b839 SR |
2307 | if (rb_event_is_commit(cpu_buffer, event)) { |
2308 | /* | |
2309 | * A commit event that is first on a page | |
2310 | * updates the write timestamp with the page stamp | |
2311 | */ | |
2312 | if (!rb_event_index(event)) | |
2313 | cpu_buffer->write_stamp = | |
2314 | cpu_buffer->commit_page->page->time_stamp; | |
2315 | else if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) { | |
2316 | delta = event->array[0]; | |
2317 | delta <<= TS_SHIFT; | |
2318 | delta += event->time_delta; | |
2319 | cpu_buffer->write_stamp += delta; | |
2320 | } else | |
2321 | cpu_buffer->write_stamp += event->time_delta; | |
2322 | } | |
a1863c21 | 2323 | } |
bf41a158 | 2324 | |
a1863c21 SR |
2325 | static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, |
2326 | struct ring_buffer_event *event) | |
2327 | { | |
2328 | local_inc(&cpu_buffer->entries); | |
2329 | rb_update_write_stamp(cpu_buffer, event); | |
fa743953 | 2330 | rb_end_commit(cpu_buffer); |
7a8e76a3 SR |
2331 | } |
2332 | ||
2333 | /** | |
2334 | * ring_buffer_unlock_commit - commit a reserved | |
2335 | * @buffer: The buffer to commit to | |
2336 | * @event: The event pointer to commit. | |
7a8e76a3 SR |
2337 | * |
2338 | * This commits the data to the ring buffer, and releases any locks held. | |
2339 | * | |
2340 | * Must be paired with ring_buffer_lock_reserve. | |
2341 | */ | |
2342 | int ring_buffer_unlock_commit(struct ring_buffer *buffer, | |
0a987751 | 2343 | struct ring_buffer_event *event) |
7a8e76a3 SR |
2344 | { |
2345 | struct ring_buffer_per_cpu *cpu_buffer; | |
2346 | int cpu = raw_smp_processor_id(); | |
2347 | ||
2348 | cpu_buffer = buffer->buffers[cpu]; | |
2349 | ||
7a8e76a3 SR |
2350 | rb_commit(cpu_buffer, event); |
2351 | ||
261842b7 SR |
2352 | trace_recursive_unlock(); |
2353 | ||
5168ae50 | 2354 | preempt_enable_notrace(); |
7a8e76a3 SR |
2355 | |
2356 | return 0; | |
2357 | } | |
c4f50183 | 2358 | EXPORT_SYMBOL_GPL(ring_buffer_unlock_commit); |
7a8e76a3 | 2359 | |
f3b9aae1 FW |
2360 | static inline void rb_event_discard(struct ring_buffer_event *event) |
2361 | { | |
69d1b839 SR |
2362 | if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) |
2363 | event = skip_time_extend(event); | |
2364 | ||
334d4169 LJ |
2365 | /* array[0] holds the actual length for the discarded event */ |
2366 | event->array[0] = rb_event_data_length(event) - RB_EVNT_HDR_SIZE; | |
2367 | event->type_len = RINGBUF_TYPE_PADDING; | |
f3b9aae1 FW |
2368 | /* time delta must be non zero */ |
2369 | if (!event->time_delta) | |
2370 | event->time_delta = 1; | |
2371 | } | |
2372 | ||
a1863c21 SR |
2373 | /* |
2374 | * Decrement the entries to the page that an event is on. | |
2375 | * The event does not even need to exist, only the pointer | |
2376 | * to the page it is on. This may only be called before the commit | |
2377 | * takes place. | |
2378 | */ | |
2379 | static inline void | |
2380 | rb_decrement_entry(struct ring_buffer_per_cpu *cpu_buffer, | |
2381 | struct ring_buffer_event *event) | |
2382 | { | |
2383 | unsigned long addr = (unsigned long)event; | |
2384 | struct buffer_page *bpage = cpu_buffer->commit_page; | |
2385 | struct buffer_page *start; | |
2386 | ||
2387 | addr &= PAGE_MASK; | |
2388 | ||
2389 | /* Do the likely case first */ | |
2390 | if (likely(bpage->page == (void *)addr)) { | |
2391 | local_dec(&bpage->entries); | |
2392 | return; | |
2393 | } | |
2394 | ||
2395 | /* | |
2396 | * Because the commit page may be on the reader page we | |
2397 | * start with the next page and check the end loop there. | |
2398 | */ | |
2399 | rb_inc_page(cpu_buffer, &bpage); | |
2400 | start = bpage; | |
2401 | do { | |
2402 | if (bpage->page == (void *)addr) { | |
2403 | local_dec(&bpage->entries); | |
2404 | return; | |
2405 | } | |
2406 | rb_inc_page(cpu_buffer, &bpage); | |
2407 | } while (bpage != start); | |
2408 | ||
2409 | /* commit not part of this buffer?? */ | |
2410 | RB_WARN_ON(cpu_buffer, 1); | |
2411 | } | |
2412 | ||
fa1b47dd SR |
2413 | /** |
2414 | * ring_buffer_commit_discard - discard an event that has not been committed | |
2415 | * @buffer: the ring buffer | |
2416 | * @event: non committed event to discard | |
2417 | * | |
dc892f73 SR |
2418 | * Sometimes an event that is in the ring buffer needs to be ignored. |
2419 | * This function lets the user discard an event in the ring buffer | |
2420 | * and then that event will not be read later. | |
2421 | * | |
2422 | * This function only works if it is called before the the item has been | |
2423 | * committed. It will try to free the event from the ring buffer | |
fa1b47dd SR |
2424 | * if another event has not been added behind it. |
2425 | * | |
2426 | * If another event has been added behind it, it will set the event | |
2427 | * up as discarded, and perform the commit. | |
2428 | * | |
2429 | * If this function is called, do not call ring_buffer_unlock_commit on | |
2430 | * the event. | |
2431 | */ | |
2432 | void ring_buffer_discard_commit(struct ring_buffer *buffer, | |
2433 | struct ring_buffer_event *event) | |
2434 | { | |
2435 | struct ring_buffer_per_cpu *cpu_buffer; | |
fa1b47dd SR |
2436 | int cpu; |
2437 | ||
2438 | /* The event is discarded regardless */ | |
f3b9aae1 | 2439 | rb_event_discard(event); |
fa1b47dd | 2440 | |
fa743953 SR |
2441 | cpu = smp_processor_id(); |
2442 | cpu_buffer = buffer->buffers[cpu]; | |
2443 | ||
fa1b47dd SR |
2444 | /* |
2445 | * This must only be called if the event has not been | |
2446 | * committed yet. Thus we can assume that preemption | |
2447 | * is still disabled. | |
2448 | */ | |
fa743953 | 2449 | RB_WARN_ON(buffer, !local_read(&cpu_buffer->committing)); |
fa1b47dd | 2450 | |
a1863c21 | 2451 | rb_decrement_entry(cpu_buffer, event); |
0f2541d2 | 2452 | if (rb_try_to_discard(cpu_buffer, event)) |
edd813bf | 2453 | goto out; |
fa1b47dd SR |
2454 | |
2455 | /* | |
2456 | * The commit is still visible by the reader, so we | |
a1863c21 | 2457 | * must still update the timestamp. |
fa1b47dd | 2458 | */ |
a1863c21 | 2459 | rb_update_write_stamp(cpu_buffer, event); |
fa1b47dd | 2460 | out: |
fa743953 | 2461 | rb_end_commit(cpu_buffer); |
fa1b47dd | 2462 | |
f3b9aae1 FW |
2463 | trace_recursive_unlock(); |
2464 | ||
5168ae50 | 2465 | preempt_enable_notrace(); |
fa1b47dd SR |
2466 | |
2467 | } | |
2468 | EXPORT_SYMBOL_GPL(ring_buffer_discard_commit); | |
2469 | ||
7a8e76a3 SR |
2470 | /** |
2471 | * ring_buffer_write - write data to the buffer without reserving | |
2472 | * @buffer: The ring buffer to write to. | |
2473 | * @length: The length of the data being written (excluding the event header) | |
2474 | * @data: The data to write to the buffer. | |
2475 | * | |
2476 | * This is like ring_buffer_lock_reserve and ring_buffer_unlock_commit as | |
2477 | * one function. If you already have the data to write to the buffer, it | |
2478 | * may be easier to simply call this function. | |
2479 | * | |
2480 | * Note, like ring_buffer_lock_reserve, the length is the length of the data | |
2481 | * and not the length of the event which would hold the header. | |
2482 | */ | |
2483 | int ring_buffer_write(struct ring_buffer *buffer, | |
2484 | unsigned long length, | |
2485 | void *data) | |
2486 | { | |
2487 | struct ring_buffer_per_cpu *cpu_buffer; | |
2488 | struct ring_buffer_event *event; | |
7a8e76a3 SR |
2489 | void *body; |
2490 | int ret = -EBUSY; | |
5168ae50 | 2491 | int cpu; |
7a8e76a3 | 2492 | |
033601a3 | 2493 | if (ring_buffer_flags != RB_BUFFERS_ON) |
a3583244 SR |
2494 | return -EBUSY; |
2495 | ||
5168ae50 | 2496 | preempt_disable_notrace(); |
bf41a158 | 2497 | |
52fbe9cd LJ |
2498 | if (atomic_read(&buffer->record_disabled)) |
2499 | goto out; | |
2500 | ||
7a8e76a3 SR |
2501 | cpu = raw_smp_processor_id(); |
2502 | ||
9e01c1b7 | 2503 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
d769041f | 2504 | goto out; |
7a8e76a3 SR |
2505 | |
2506 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 SR |
2507 | |
2508 | if (atomic_read(&cpu_buffer->record_disabled)) | |
2509 | goto out; | |
2510 | ||
be957c44 SR |
2511 | if (length > BUF_MAX_DATA_SIZE) |
2512 | goto out; | |
2513 | ||
62f0b3eb | 2514 | event = rb_reserve_next_event(buffer, cpu_buffer, length); |
7a8e76a3 SR |
2515 | if (!event) |
2516 | goto out; | |
2517 | ||
2518 | body = rb_event_data(event); | |
2519 | ||
2520 | memcpy(body, data, length); | |
2521 | ||
2522 | rb_commit(cpu_buffer, event); | |
2523 | ||
2524 | ret = 0; | |
2525 | out: | |
5168ae50 | 2526 | preempt_enable_notrace(); |
7a8e76a3 SR |
2527 | |
2528 | return ret; | |
2529 | } | |
c4f50183 | 2530 | EXPORT_SYMBOL_GPL(ring_buffer_write); |
7a8e76a3 | 2531 | |
34a148bf | 2532 | static int rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) |
bf41a158 SR |
2533 | { |
2534 | struct buffer_page *reader = cpu_buffer->reader_page; | |
77ae365e | 2535 | struct buffer_page *head = rb_set_head_page(cpu_buffer); |
bf41a158 SR |
2536 | struct buffer_page *commit = cpu_buffer->commit_page; |
2537 | ||
77ae365e SR |
2538 | /* In case of error, head will be NULL */ |
2539 | if (unlikely(!head)) | |
2540 | return 1; | |
2541 | ||
bf41a158 SR |
2542 | return reader->read == rb_page_commit(reader) && |
2543 | (commit == reader || | |
2544 | (commit == head && | |
2545 | head->read == rb_page_commit(commit))); | |
2546 | } | |
2547 | ||
7a8e76a3 SR |
2548 | /** |
2549 | * ring_buffer_record_disable - stop all writes into the buffer | |
2550 | * @buffer: The ring buffer to stop writes to. | |
2551 | * | |
2552 | * This prevents all writes to the buffer. Any attempt to write | |
2553 | * to the buffer after this will fail and return NULL. | |
2554 | * | |
2555 | * The caller should call synchronize_sched() after this. | |
2556 | */ | |
2557 | void ring_buffer_record_disable(struct ring_buffer *buffer) | |
2558 | { | |
2559 | atomic_inc(&buffer->record_disabled); | |
2560 | } | |
c4f50183 | 2561 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable); |
7a8e76a3 SR |
2562 | |
2563 | /** | |
2564 | * ring_buffer_record_enable - enable writes to the buffer | |
2565 | * @buffer: The ring buffer to enable writes | |
2566 | * | |
2567 | * Note, multiple disables will need the same number of enables | |
c41b20e7 | 2568 | * to truly enable the writing (much like preempt_disable). |
7a8e76a3 SR |
2569 | */ |
2570 | void ring_buffer_record_enable(struct ring_buffer *buffer) | |
2571 | { | |
2572 | atomic_dec(&buffer->record_disabled); | |
2573 | } | |
c4f50183 | 2574 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable); |
7a8e76a3 SR |
2575 | |
2576 | /** | |
2577 | * ring_buffer_record_disable_cpu - stop all writes into the cpu_buffer | |
2578 | * @buffer: The ring buffer to stop writes to. | |
2579 | * @cpu: The CPU buffer to stop | |
2580 | * | |
2581 | * This prevents all writes to the buffer. Any attempt to write | |
2582 | * to the buffer after this will fail and return NULL. | |
2583 | * | |
2584 | * The caller should call synchronize_sched() after this. | |
2585 | */ | |
2586 | void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu) | |
2587 | { | |
2588 | struct ring_buffer_per_cpu *cpu_buffer; | |
2589 | ||
9e01c1b7 | 2590 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 2591 | return; |
7a8e76a3 SR |
2592 | |
2593 | cpu_buffer = buffer->buffers[cpu]; | |
2594 | atomic_inc(&cpu_buffer->record_disabled); | |
2595 | } | |
c4f50183 | 2596 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable_cpu); |
7a8e76a3 SR |
2597 | |
2598 | /** | |
2599 | * ring_buffer_record_enable_cpu - enable writes to the buffer | |
2600 | * @buffer: The ring buffer to enable writes | |
2601 | * @cpu: The CPU to enable. | |
2602 | * | |
2603 | * Note, multiple disables will need the same number of enables | |
c41b20e7 | 2604 | * to truly enable the writing (much like preempt_disable). |
7a8e76a3 SR |
2605 | */ |
2606 | void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu) | |
2607 | { | |
2608 | struct ring_buffer_per_cpu *cpu_buffer; | |
2609 | ||
9e01c1b7 | 2610 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 2611 | return; |
7a8e76a3 SR |
2612 | |
2613 | cpu_buffer = buffer->buffers[cpu]; | |
2614 | atomic_dec(&cpu_buffer->record_disabled); | |
2615 | } | |
c4f50183 | 2616 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu); |
7a8e76a3 | 2617 | |
f6195aa0 SR |
2618 | /* |
2619 | * The total entries in the ring buffer is the running counter | |
2620 | * of entries entered into the ring buffer, minus the sum of | |
2621 | * the entries read from the ring buffer and the number of | |
2622 | * entries that were overwritten. | |
2623 | */ | |
2624 | static inline unsigned long | |
2625 | rb_num_of_entries(struct ring_buffer_per_cpu *cpu_buffer) | |
2626 | { | |
2627 | return local_read(&cpu_buffer->entries) - | |
2628 | (local_read(&cpu_buffer->overrun) + cpu_buffer->read); | |
2629 | } | |
2630 | ||
7a8e76a3 SR |
2631 | /** |
2632 | * ring_buffer_entries_cpu - get the number of entries in a cpu buffer | |
2633 | * @buffer: The ring buffer | |
2634 | * @cpu: The per CPU buffer to get the entries from. | |
2635 | */ | |
2636 | unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu) | |
2637 | { | |
2638 | struct ring_buffer_per_cpu *cpu_buffer; | |
2639 | ||
9e01c1b7 | 2640 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 2641 | return 0; |
7a8e76a3 SR |
2642 | |
2643 | cpu_buffer = buffer->buffers[cpu]; | |
554f786e | 2644 | |
f6195aa0 | 2645 | return rb_num_of_entries(cpu_buffer); |
7a8e76a3 | 2646 | } |
c4f50183 | 2647 | EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu); |
7a8e76a3 SR |
2648 | |
2649 | /** | |
2650 | * ring_buffer_overrun_cpu - get the number of overruns in a cpu_buffer | |
2651 | * @buffer: The ring buffer | |
2652 | * @cpu: The per CPU buffer to get the number of overruns from | |
2653 | */ | |
2654 | unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu) | |
2655 | { | |
2656 | struct ring_buffer_per_cpu *cpu_buffer; | |
8aabee57 | 2657 | unsigned long ret; |
7a8e76a3 | 2658 | |
9e01c1b7 | 2659 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 2660 | return 0; |
7a8e76a3 SR |
2661 | |
2662 | cpu_buffer = buffer->buffers[cpu]; | |
77ae365e | 2663 | ret = local_read(&cpu_buffer->overrun); |
554f786e SR |
2664 | |
2665 | return ret; | |
7a8e76a3 | 2666 | } |
c4f50183 | 2667 | EXPORT_SYMBOL_GPL(ring_buffer_overrun_cpu); |
7a8e76a3 | 2668 | |
f0d2c681 SR |
2669 | /** |
2670 | * ring_buffer_commit_overrun_cpu - get the number of overruns caused by commits | |
2671 | * @buffer: The ring buffer | |
2672 | * @cpu: The per CPU buffer to get the number of overruns from | |
2673 | */ | |
2674 | unsigned long | |
2675 | ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu) | |
2676 | { | |
2677 | struct ring_buffer_per_cpu *cpu_buffer; | |
2678 | unsigned long ret; | |
2679 | ||
2680 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
2681 | return 0; | |
2682 | ||
2683 | cpu_buffer = buffer->buffers[cpu]; | |
77ae365e | 2684 | ret = local_read(&cpu_buffer->commit_overrun); |
f0d2c681 SR |
2685 | |
2686 | return ret; | |
2687 | } | |
2688 | EXPORT_SYMBOL_GPL(ring_buffer_commit_overrun_cpu); | |
2689 | ||
7a8e76a3 SR |
2690 | /** |
2691 | * ring_buffer_entries - get the number of entries in a buffer | |
2692 | * @buffer: The ring buffer | |
2693 | * | |
2694 | * Returns the total number of entries in the ring buffer | |
2695 | * (all CPU entries) | |
2696 | */ | |
2697 | unsigned long ring_buffer_entries(struct ring_buffer *buffer) | |
2698 | { | |
2699 | struct ring_buffer_per_cpu *cpu_buffer; | |
2700 | unsigned long entries = 0; | |
2701 | int cpu; | |
2702 | ||
2703 | /* if you care about this being correct, lock the buffer */ | |
2704 | for_each_buffer_cpu(buffer, cpu) { | |
2705 | cpu_buffer = buffer->buffers[cpu]; | |
f6195aa0 | 2706 | entries += rb_num_of_entries(cpu_buffer); |
7a8e76a3 SR |
2707 | } |
2708 | ||
2709 | return entries; | |
2710 | } | |
c4f50183 | 2711 | EXPORT_SYMBOL_GPL(ring_buffer_entries); |
7a8e76a3 SR |
2712 | |
2713 | /** | |
67b394f7 | 2714 | * ring_buffer_overruns - get the number of overruns in buffer |
7a8e76a3 SR |
2715 | * @buffer: The ring buffer |
2716 | * | |
2717 | * Returns the total number of overruns in the ring buffer | |
2718 | * (all CPU entries) | |
2719 | */ | |
2720 | unsigned long ring_buffer_overruns(struct ring_buffer *buffer) | |
2721 | { | |
2722 | struct ring_buffer_per_cpu *cpu_buffer; | |
2723 | unsigned long overruns = 0; | |
2724 | int cpu; | |
2725 | ||
2726 | /* if you care about this being correct, lock the buffer */ | |
2727 | for_each_buffer_cpu(buffer, cpu) { | |
2728 | cpu_buffer = buffer->buffers[cpu]; | |
77ae365e | 2729 | overruns += local_read(&cpu_buffer->overrun); |
7a8e76a3 SR |
2730 | } |
2731 | ||
2732 | return overruns; | |
2733 | } | |
c4f50183 | 2734 | EXPORT_SYMBOL_GPL(ring_buffer_overruns); |
7a8e76a3 | 2735 | |
642edba5 | 2736 | static void rb_iter_reset(struct ring_buffer_iter *iter) |
7a8e76a3 SR |
2737 | { |
2738 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
2739 | ||
d769041f SR |
2740 | /* Iterator usage is expected to have record disabled */ |
2741 | if (list_empty(&cpu_buffer->reader_page->list)) { | |
77ae365e SR |
2742 | iter->head_page = rb_set_head_page(cpu_buffer); |
2743 | if (unlikely(!iter->head_page)) | |
2744 | return; | |
2745 | iter->head = iter->head_page->read; | |
d769041f SR |
2746 | } else { |
2747 | iter->head_page = cpu_buffer->reader_page; | |
6f807acd | 2748 | iter->head = cpu_buffer->reader_page->read; |
d769041f SR |
2749 | } |
2750 | if (iter->head) | |
2751 | iter->read_stamp = cpu_buffer->read_stamp; | |
2752 | else | |
abc9b56d | 2753 | iter->read_stamp = iter->head_page->page->time_stamp; |
492a74f4 SR |
2754 | iter->cache_reader_page = cpu_buffer->reader_page; |
2755 | iter->cache_read = cpu_buffer->read; | |
642edba5 | 2756 | } |
f83c9d0f | 2757 | |
642edba5 SR |
2758 | /** |
2759 | * ring_buffer_iter_reset - reset an iterator | |
2760 | * @iter: The iterator to reset | |
2761 | * | |
2762 | * Resets the iterator, so that it will start from the beginning | |
2763 | * again. | |
2764 | */ | |
2765 | void ring_buffer_iter_reset(struct ring_buffer_iter *iter) | |
2766 | { | |
554f786e | 2767 | struct ring_buffer_per_cpu *cpu_buffer; |
642edba5 SR |
2768 | unsigned long flags; |
2769 | ||
554f786e SR |
2770 | if (!iter) |
2771 | return; | |
2772 | ||
2773 | cpu_buffer = iter->cpu_buffer; | |
2774 | ||
642edba5 SR |
2775 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
2776 | rb_iter_reset(iter); | |
f83c9d0f | 2777 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
7a8e76a3 | 2778 | } |
c4f50183 | 2779 | EXPORT_SYMBOL_GPL(ring_buffer_iter_reset); |
7a8e76a3 SR |
2780 | |
2781 | /** | |
2782 | * ring_buffer_iter_empty - check if an iterator has no more to read | |
2783 | * @iter: The iterator to check | |
2784 | */ | |
2785 | int ring_buffer_iter_empty(struct ring_buffer_iter *iter) | |
2786 | { | |
2787 | struct ring_buffer_per_cpu *cpu_buffer; | |
2788 | ||
2789 | cpu_buffer = iter->cpu_buffer; | |
2790 | ||
bf41a158 SR |
2791 | return iter->head_page == cpu_buffer->commit_page && |
2792 | iter->head == rb_commit_index(cpu_buffer); | |
7a8e76a3 | 2793 | } |
c4f50183 | 2794 | EXPORT_SYMBOL_GPL(ring_buffer_iter_empty); |
7a8e76a3 SR |
2795 | |
2796 | static void | |
2797 | rb_update_read_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
2798 | struct ring_buffer_event *event) | |
2799 | { | |
2800 | u64 delta; | |
2801 | ||
334d4169 | 2802 | switch (event->type_len) { |
7a8e76a3 SR |
2803 | case RINGBUF_TYPE_PADDING: |
2804 | return; | |
2805 | ||
2806 | case RINGBUF_TYPE_TIME_EXTEND: | |
2807 | delta = event->array[0]; | |
2808 | delta <<= TS_SHIFT; | |
2809 | delta += event->time_delta; | |
2810 | cpu_buffer->read_stamp += delta; | |
2811 | return; | |
2812 | ||
2813 | case RINGBUF_TYPE_TIME_STAMP: | |
2814 | /* FIXME: not implemented */ | |
2815 | return; | |
2816 | ||
2817 | case RINGBUF_TYPE_DATA: | |
2818 | cpu_buffer->read_stamp += event->time_delta; | |
2819 | return; | |
2820 | ||
2821 | default: | |
2822 | BUG(); | |
2823 | } | |
2824 | return; | |
2825 | } | |
2826 | ||
2827 | static void | |
2828 | rb_update_iter_read_stamp(struct ring_buffer_iter *iter, | |
2829 | struct ring_buffer_event *event) | |
2830 | { | |
2831 | u64 delta; | |
2832 | ||
334d4169 | 2833 | switch (event->type_len) { |
7a8e76a3 SR |
2834 | case RINGBUF_TYPE_PADDING: |
2835 | return; | |
2836 | ||
2837 | case RINGBUF_TYPE_TIME_EXTEND: | |
2838 | delta = event->array[0]; | |
2839 | delta <<= TS_SHIFT; | |
2840 | delta += event->time_delta; | |
2841 | iter->read_stamp += delta; | |
2842 | return; | |
2843 | ||
2844 | case RINGBUF_TYPE_TIME_STAMP: | |
2845 | /* FIXME: not implemented */ | |
2846 | return; | |
2847 | ||
2848 | case RINGBUF_TYPE_DATA: | |
2849 | iter->read_stamp += event->time_delta; | |
2850 | return; | |
2851 | ||
2852 | default: | |
2853 | BUG(); | |
2854 | } | |
2855 | return; | |
2856 | } | |
2857 | ||
d769041f SR |
2858 | static struct buffer_page * |
2859 | rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) | |
7a8e76a3 | 2860 | { |
d769041f | 2861 | struct buffer_page *reader = NULL; |
66a8cb95 | 2862 | unsigned long overwrite; |
d769041f | 2863 | unsigned long flags; |
818e3dd3 | 2864 | int nr_loops = 0; |
77ae365e | 2865 | int ret; |
d769041f | 2866 | |
3e03fb7f | 2867 | local_irq_save(flags); |
0199c4e6 | 2868 | arch_spin_lock(&cpu_buffer->lock); |
d769041f SR |
2869 | |
2870 | again: | |
818e3dd3 SR |
2871 | /* |
2872 | * This should normally only loop twice. But because the | |
2873 | * start of the reader inserts an empty page, it causes | |
2874 | * a case where we will loop three times. There should be no | |
2875 | * reason to loop four times (that I know of). | |
2876 | */ | |
3e89c7bb | 2877 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 3)) { |
818e3dd3 SR |
2878 | reader = NULL; |
2879 | goto out; | |
2880 | } | |
2881 | ||
d769041f SR |
2882 | reader = cpu_buffer->reader_page; |
2883 | ||
2884 | /* If there's more to read, return this page */ | |
bf41a158 | 2885 | if (cpu_buffer->reader_page->read < rb_page_size(reader)) |
d769041f SR |
2886 | goto out; |
2887 | ||
2888 | /* Never should we have an index greater than the size */ | |
3e89c7bb SR |
2889 | if (RB_WARN_ON(cpu_buffer, |
2890 | cpu_buffer->reader_page->read > rb_page_size(reader))) | |
2891 | goto out; | |
d769041f SR |
2892 | |
2893 | /* check if we caught up to the tail */ | |
2894 | reader = NULL; | |
bf41a158 | 2895 | if (cpu_buffer->commit_page == cpu_buffer->reader_page) |
d769041f | 2896 | goto out; |
7a8e76a3 SR |
2897 | |
2898 | /* | |
d769041f | 2899 | * Reset the reader page to size zero. |
7a8e76a3 | 2900 | */ |
77ae365e SR |
2901 | local_set(&cpu_buffer->reader_page->write, 0); |
2902 | local_set(&cpu_buffer->reader_page->entries, 0); | |
2903 | local_set(&cpu_buffer->reader_page->page->commit, 0); | |
ff0ff84a | 2904 | cpu_buffer->reader_page->real_end = 0; |
7a8e76a3 | 2905 | |
77ae365e SR |
2906 | spin: |
2907 | /* | |
2908 | * Splice the empty reader page into the list around the head. | |
2909 | */ | |
2910 | reader = rb_set_head_page(cpu_buffer); | |
0e1ff5d7 | 2911 | cpu_buffer->reader_page->list.next = rb_list_head(reader->list.next); |
d769041f | 2912 | cpu_buffer->reader_page->list.prev = reader->list.prev; |
bf41a158 | 2913 | |
3adc54fa SR |
2914 | /* |
2915 | * cpu_buffer->pages just needs to point to the buffer, it | |
2916 | * has no specific buffer page to point to. Lets move it out | |
2917 | * of our way so we don't accidently swap it. | |
2918 | */ | |
2919 | cpu_buffer->pages = reader->list.prev; | |
2920 | ||
77ae365e SR |
2921 | /* The reader page will be pointing to the new head */ |
2922 | rb_set_list_to_head(cpu_buffer, &cpu_buffer->reader_page->list); | |
7a8e76a3 | 2923 | |
66a8cb95 SR |
2924 | /* |
2925 | * We want to make sure we read the overruns after we set up our | |
2926 | * pointers to the next object. The writer side does a | |
2927 | * cmpxchg to cross pages which acts as the mb on the writer | |
2928 | * side. Note, the reader will constantly fail the swap | |
2929 | * while the writer is updating the pointers, so this | |
2930 | * guarantees that the overwrite recorded here is the one we | |
2931 | * want to compare with the last_overrun. | |
2932 | */ | |
2933 | smp_mb(); | |
2934 | overwrite = local_read(&(cpu_buffer->overrun)); | |
2935 | ||
77ae365e SR |
2936 | /* |
2937 | * Here's the tricky part. | |
2938 | * | |
2939 | * We need to move the pointer past the header page. | |
2940 | * But we can only do that if a writer is not currently | |
2941 | * moving it. The page before the header page has the | |
2942 | * flag bit '1' set if it is pointing to the page we want. | |
2943 | * but if the writer is in the process of moving it | |
2944 | * than it will be '2' or already moved '0'. | |
2945 | */ | |
2946 | ||
2947 | ret = rb_head_page_replace(reader, cpu_buffer->reader_page); | |
7a8e76a3 SR |
2948 | |
2949 | /* | |
77ae365e | 2950 | * If we did not convert it, then we must try again. |
7a8e76a3 | 2951 | */ |
77ae365e SR |
2952 | if (!ret) |
2953 | goto spin; | |
7a8e76a3 | 2954 | |
77ae365e SR |
2955 | /* |
2956 | * Yeah! We succeeded in replacing the page. | |
2957 | * | |
2958 | * Now make the new head point back to the reader page. | |
2959 | */ | |
5ded3dc6 | 2960 | rb_list_head(reader->list.next)->prev = &cpu_buffer->reader_page->list; |
77ae365e | 2961 | rb_inc_page(cpu_buffer, &cpu_buffer->head_page); |
d769041f SR |
2962 | |
2963 | /* Finally update the reader page to the new head */ | |
2964 | cpu_buffer->reader_page = reader; | |
2965 | rb_reset_reader_page(cpu_buffer); | |
2966 | ||
66a8cb95 SR |
2967 | if (overwrite != cpu_buffer->last_overrun) { |
2968 | cpu_buffer->lost_events = overwrite - cpu_buffer->last_overrun; | |
2969 | cpu_buffer->last_overrun = overwrite; | |
2970 | } | |
2971 | ||
d769041f SR |
2972 | goto again; |
2973 | ||
2974 | out: | |
0199c4e6 | 2975 | arch_spin_unlock(&cpu_buffer->lock); |
3e03fb7f | 2976 | local_irq_restore(flags); |
d769041f SR |
2977 | |
2978 | return reader; | |
2979 | } | |
2980 | ||
2981 | static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer) | |
2982 | { | |
2983 | struct ring_buffer_event *event; | |
2984 | struct buffer_page *reader; | |
2985 | unsigned length; | |
2986 | ||
2987 | reader = rb_get_reader_page(cpu_buffer); | |
7a8e76a3 | 2988 | |
d769041f | 2989 | /* This function should not be called when buffer is empty */ |
3e89c7bb SR |
2990 | if (RB_WARN_ON(cpu_buffer, !reader)) |
2991 | return; | |
7a8e76a3 | 2992 | |
d769041f SR |
2993 | event = rb_reader_event(cpu_buffer); |
2994 | ||
a1863c21 | 2995 | if (event->type_len <= RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
e4906eff | 2996 | cpu_buffer->read++; |
d769041f SR |
2997 | |
2998 | rb_update_read_stamp(cpu_buffer, event); | |
2999 | ||
3000 | length = rb_event_length(event); | |
6f807acd | 3001 | cpu_buffer->reader_page->read += length; |
7a8e76a3 SR |
3002 | } |
3003 | ||
3004 | static void rb_advance_iter(struct ring_buffer_iter *iter) | |
3005 | { | |
7a8e76a3 SR |
3006 | struct ring_buffer_per_cpu *cpu_buffer; |
3007 | struct ring_buffer_event *event; | |
3008 | unsigned length; | |
3009 | ||
3010 | cpu_buffer = iter->cpu_buffer; | |
7a8e76a3 SR |
3011 | |
3012 | /* | |
3013 | * Check if we are at the end of the buffer. | |
3014 | */ | |
bf41a158 | 3015 | if (iter->head >= rb_page_size(iter->head_page)) { |
ea05b57c SR |
3016 | /* discarded commits can make the page empty */ |
3017 | if (iter->head_page == cpu_buffer->commit_page) | |
3e89c7bb | 3018 | return; |
d769041f | 3019 | rb_inc_iter(iter); |
7a8e76a3 SR |
3020 | return; |
3021 | } | |
3022 | ||
3023 | event = rb_iter_head_event(iter); | |
3024 | ||
3025 | length = rb_event_length(event); | |
3026 | ||
3027 | /* | |
3028 | * This should not be called to advance the header if we are | |
3029 | * at the tail of the buffer. | |
3030 | */ | |
3e89c7bb | 3031 | if (RB_WARN_ON(cpu_buffer, |
f536aafc | 3032 | (iter->head_page == cpu_buffer->commit_page) && |
3e89c7bb SR |
3033 | (iter->head + length > rb_commit_index(cpu_buffer)))) |
3034 | return; | |
7a8e76a3 SR |
3035 | |
3036 | rb_update_iter_read_stamp(iter, event); | |
3037 | ||
3038 | iter->head += length; | |
3039 | ||
3040 | /* check for end of page padding */ | |
bf41a158 SR |
3041 | if ((iter->head >= rb_page_size(iter->head_page)) && |
3042 | (iter->head_page != cpu_buffer->commit_page)) | |
7a8e76a3 SR |
3043 | rb_advance_iter(iter); |
3044 | } | |
3045 | ||
66a8cb95 SR |
3046 | static int rb_lost_events(struct ring_buffer_per_cpu *cpu_buffer) |
3047 | { | |
3048 | return cpu_buffer->lost_events; | |
3049 | } | |
3050 | ||
f83c9d0f | 3051 | static struct ring_buffer_event * |
66a8cb95 SR |
3052 | rb_buffer_peek(struct ring_buffer_per_cpu *cpu_buffer, u64 *ts, |
3053 | unsigned long *lost_events) | |
7a8e76a3 | 3054 | { |
7a8e76a3 | 3055 | struct ring_buffer_event *event; |
d769041f | 3056 | struct buffer_page *reader; |
818e3dd3 | 3057 | int nr_loops = 0; |
7a8e76a3 | 3058 | |
7a8e76a3 | 3059 | again: |
818e3dd3 | 3060 | /* |
69d1b839 SR |
3061 | * We repeat when a time extend is encountered. |
3062 | * Since the time extend is always attached to a data event, | |
3063 | * we should never loop more than once. | |
3064 | * (We never hit the following condition more than twice). | |
818e3dd3 | 3065 | */ |
69d1b839 | 3066 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 2)) |
818e3dd3 | 3067 | return NULL; |
818e3dd3 | 3068 | |
d769041f SR |
3069 | reader = rb_get_reader_page(cpu_buffer); |
3070 | if (!reader) | |
7a8e76a3 SR |
3071 | return NULL; |
3072 | ||
d769041f | 3073 | event = rb_reader_event(cpu_buffer); |
7a8e76a3 | 3074 | |
334d4169 | 3075 | switch (event->type_len) { |
7a8e76a3 | 3076 | case RINGBUF_TYPE_PADDING: |
2d622719 TZ |
3077 | if (rb_null_event(event)) |
3078 | RB_WARN_ON(cpu_buffer, 1); | |
3079 | /* | |
3080 | * Because the writer could be discarding every | |
3081 | * event it creates (which would probably be bad) | |
3082 | * if we were to go back to "again" then we may never | |
3083 | * catch up, and will trigger the warn on, or lock | |
3084 | * the box. Return the padding, and we will release | |
3085 | * the current locks, and try again. | |
3086 | */ | |
2d622719 | 3087 | return event; |
7a8e76a3 SR |
3088 | |
3089 | case RINGBUF_TYPE_TIME_EXTEND: | |
3090 | /* Internal data, OK to advance */ | |
d769041f | 3091 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
3092 | goto again; |
3093 | ||
3094 | case RINGBUF_TYPE_TIME_STAMP: | |
3095 | /* FIXME: not implemented */ | |
d769041f | 3096 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
3097 | goto again; |
3098 | ||
3099 | case RINGBUF_TYPE_DATA: | |
3100 | if (ts) { | |
3101 | *ts = cpu_buffer->read_stamp + event->time_delta; | |
d8eeb2d3 | 3102 | ring_buffer_normalize_time_stamp(cpu_buffer->buffer, |
37886f6a | 3103 | cpu_buffer->cpu, ts); |
7a8e76a3 | 3104 | } |
66a8cb95 SR |
3105 | if (lost_events) |
3106 | *lost_events = rb_lost_events(cpu_buffer); | |
7a8e76a3 SR |
3107 | return event; |
3108 | ||
3109 | default: | |
3110 | BUG(); | |
3111 | } | |
3112 | ||
3113 | return NULL; | |
3114 | } | |
c4f50183 | 3115 | EXPORT_SYMBOL_GPL(ring_buffer_peek); |
7a8e76a3 | 3116 | |
f83c9d0f SR |
3117 | static struct ring_buffer_event * |
3118 | rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) | |
7a8e76a3 SR |
3119 | { |
3120 | struct ring_buffer *buffer; | |
3121 | struct ring_buffer_per_cpu *cpu_buffer; | |
3122 | struct ring_buffer_event *event; | |
818e3dd3 | 3123 | int nr_loops = 0; |
7a8e76a3 | 3124 | |
7a8e76a3 SR |
3125 | cpu_buffer = iter->cpu_buffer; |
3126 | buffer = cpu_buffer->buffer; | |
3127 | ||
492a74f4 SR |
3128 | /* |
3129 | * Check if someone performed a consuming read to | |
3130 | * the buffer. A consuming read invalidates the iterator | |
3131 | * and we need to reset the iterator in this case. | |
3132 | */ | |
3133 | if (unlikely(iter->cache_read != cpu_buffer->read || | |
3134 | iter->cache_reader_page != cpu_buffer->reader_page)) | |
3135 | rb_iter_reset(iter); | |
3136 | ||
7a8e76a3 | 3137 | again: |
3c05d748 SR |
3138 | if (ring_buffer_iter_empty(iter)) |
3139 | return NULL; | |
3140 | ||
818e3dd3 | 3141 | /* |
69d1b839 SR |
3142 | * We repeat when a time extend is encountered. |
3143 | * Since the time extend is always attached to a data event, | |
3144 | * we should never loop more than once. | |
3145 | * (We never hit the following condition more than twice). | |
818e3dd3 | 3146 | */ |
69d1b839 | 3147 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 2)) |
818e3dd3 | 3148 | return NULL; |
818e3dd3 | 3149 | |
7a8e76a3 SR |
3150 | if (rb_per_cpu_empty(cpu_buffer)) |
3151 | return NULL; | |
3152 | ||
3c05d748 SR |
3153 | if (iter->head >= local_read(&iter->head_page->page->commit)) { |
3154 | rb_inc_iter(iter); | |
3155 | goto again; | |
3156 | } | |
3157 | ||
7a8e76a3 SR |
3158 | event = rb_iter_head_event(iter); |
3159 | ||
334d4169 | 3160 | switch (event->type_len) { |
7a8e76a3 | 3161 | case RINGBUF_TYPE_PADDING: |
2d622719 TZ |
3162 | if (rb_null_event(event)) { |
3163 | rb_inc_iter(iter); | |
3164 | goto again; | |
3165 | } | |
3166 | rb_advance_iter(iter); | |
3167 | return event; | |
7a8e76a3 SR |
3168 | |
3169 | case RINGBUF_TYPE_TIME_EXTEND: | |
3170 | /* Internal data, OK to advance */ | |
3171 | rb_advance_iter(iter); | |
3172 | goto again; | |
3173 | ||
3174 | case RINGBUF_TYPE_TIME_STAMP: | |
3175 | /* FIXME: not implemented */ | |
3176 | rb_advance_iter(iter); | |
3177 | goto again; | |
3178 | ||
3179 | case RINGBUF_TYPE_DATA: | |
3180 | if (ts) { | |
3181 | *ts = iter->read_stamp + event->time_delta; | |
37886f6a SR |
3182 | ring_buffer_normalize_time_stamp(buffer, |
3183 | cpu_buffer->cpu, ts); | |
7a8e76a3 SR |
3184 | } |
3185 | return event; | |
3186 | ||
3187 | default: | |
3188 | BUG(); | |
3189 | } | |
3190 | ||
3191 | return NULL; | |
3192 | } | |
c4f50183 | 3193 | EXPORT_SYMBOL_GPL(ring_buffer_iter_peek); |
7a8e76a3 | 3194 | |
8d707e8e SR |
3195 | static inline int rb_ok_to_lock(void) |
3196 | { | |
3197 | /* | |
3198 | * If an NMI die dumps out the content of the ring buffer | |
3199 | * do not grab locks. We also permanently disable the ring | |
3200 | * buffer too. A one time deal is all you get from reading | |
3201 | * the ring buffer from an NMI. | |
3202 | */ | |
464e85eb | 3203 | if (likely(!in_nmi())) |
8d707e8e SR |
3204 | return 1; |
3205 | ||
3206 | tracing_off_permanent(); | |
3207 | return 0; | |
3208 | } | |
3209 | ||
f83c9d0f SR |
3210 | /** |
3211 | * ring_buffer_peek - peek at the next event to be read | |
3212 | * @buffer: The ring buffer to read | |
3213 | * @cpu: The cpu to peak at | |
3214 | * @ts: The timestamp counter of this event. | |
66a8cb95 | 3215 | * @lost_events: a variable to store if events were lost (may be NULL) |
f83c9d0f SR |
3216 | * |
3217 | * This will return the event that will be read next, but does | |
3218 | * not consume the data. | |
3219 | */ | |
3220 | struct ring_buffer_event * | |
66a8cb95 SR |
3221 | ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts, |
3222 | unsigned long *lost_events) | |
f83c9d0f SR |
3223 | { |
3224 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
8aabee57 | 3225 | struct ring_buffer_event *event; |
f83c9d0f | 3226 | unsigned long flags; |
8d707e8e | 3227 | int dolock; |
f83c9d0f | 3228 | |
554f786e | 3229 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 3230 | return NULL; |
554f786e | 3231 | |
8d707e8e | 3232 | dolock = rb_ok_to_lock(); |
2d622719 | 3233 | again: |
8d707e8e SR |
3234 | local_irq_save(flags); |
3235 | if (dolock) | |
3236 | spin_lock(&cpu_buffer->reader_lock); | |
66a8cb95 | 3237 | event = rb_buffer_peek(cpu_buffer, ts, lost_events); |
469535a5 RR |
3238 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
3239 | rb_advance_reader(cpu_buffer); | |
8d707e8e SR |
3240 | if (dolock) |
3241 | spin_unlock(&cpu_buffer->reader_lock); | |
3242 | local_irq_restore(flags); | |
f83c9d0f | 3243 | |
1b959e18 | 3244 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
2d622719 | 3245 | goto again; |
2d622719 | 3246 | |
f83c9d0f SR |
3247 | return event; |
3248 | } | |
3249 | ||
3250 | /** | |
3251 | * ring_buffer_iter_peek - peek at the next event to be read | |
3252 | * @iter: The ring buffer iterator | |
3253 | * @ts: The timestamp counter of this event. | |
3254 | * | |
3255 | * This will return the event that will be read next, but does | |
3256 | * not increment the iterator. | |
3257 | */ | |
3258 | struct ring_buffer_event * | |
3259 | ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) | |
3260 | { | |
3261 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
3262 | struct ring_buffer_event *event; | |
3263 | unsigned long flags; | |
3264 | ||
2d622719 | 3265 | again: |
f83c9d0f SR |
3266 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
3267 | event = rb_iter_peek(iter, ts); | |
3268 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
3269 | ||
1b959e18 | 3270 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
2d622719 | 3271 | goto again; |
2d622719 | 3272 | |
f83c9d0f SR |
3273 | return event; |
3274 | } | |
3275 | ||
7a8e76a3 SR |
3276 | /** |
3277 | * ring_buffer_consume - return an event and consume it | |
3278 | * @buffer: The ring buffer to get the next event from | |
66a8cb95 SR |
3279 | * @cpu: the cpu to read the buffer from |
3280 | * @ts: a variable to store the timestamp (may be NULL) | |
3281 | * @lost_events: a variable to store if events were lost (may be NULL) | |
7a8e76a3 SR |
3282 | * |
3283 | * Returns the next event in the ring buffer, and that event is consumed. | |
3284 | * Meaning, that sequential reads will keep returning a different event, | |
3285 | * and eventually empty the ring buffer if the producer is slower. | |
3286 | */ | |
3287 | struct ring_buffer_event * | |
66a8cb95 SR |
3288 | ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts, |
3289 | unsigned long *lost_events) | |
7a8e76a3 | 3290 | { |
554f786e SR |
3291 | struct ring_buffer_per_cpu *cpu_buffer; |
3292 | struct ring_buffer_event *event = NULL; | |
f83c9d0f | 3293 | unsigned long flags; |
8d707e8e SR |
3294 | int dolock; |
3295 | ||
3296 | dolock = rb_ok_to_lock(); | |
7a8e76a3 | 3297 | |
2d622719 | 3298 | again: |
554f786e SR |
3299 | /* might be called in atomic */ |
3300 | preempt_disable(); | |
3301 | ||
9e01c1b7 | 3302 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
554f786e | 3303 | goto out; |
7a8e76a3 | 3304 | |
554f786e | 3305 | cpu_buffer = buffer->buffers[cpu]; |
8d707e8e SR |
3306 | local_irq_save(flags); |
3307 | if (dolock) | |
3308 | spin_lock(&cpu_buffer->reader_lock); | |
f83c9d0f | 3309 | |
66a8cb95 SR |
3310 | event = rb_buffer_peek(cpu_buffer, ts, lost_events); |
3311 | if (event) { | |
3312 | cpu_buffer->lost_events = 0; | |
469535a5 | 3313 | rb_advance_reader(cpu_buffer); |
66a8cb95 | 3314 | } |
7a8e76a3 | 3315 | |
8d707e8e SR |
3316 | if (dolock) |
3317 | spin_unlock(&cpu_buffer->reader_lock); | |
3318 | local_irq_restore(flags); | |
f83c9d0f | 3319 | |
554f786e SR |
3320 | out: |
3321 | preempt_enable(); | |
3322 | ||
1b959e18 | 3323 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
2d622719 | 3324 | goto again; |
2d622719 | 3325 | |
7a8e76a3 SR |
3326 | return event; |
3327 | } | |
c4f50183 | 3328 | EXPORT_SYMBOL_GPL(ring_buffer_consume); |
7a8e76a3 SR |
3329 | |
3330 | /** | |
72c9ddfd | 3331 | * ring_buffer_read_prepare - Prepare for a non consuming read of the buffer |
7a8e76a3 SR |
3332 | * @buffer: The ring buffer to read from |
3333 | * @cpu: The cpu buffer to iterate over | |
3334 | * | |
72c9ddfd DM |
3335 | * This performs the initial preparations necessary to iterate |
3336 | * through the buffer. Memory is allocated, buffer recording | |
3337 | * is disabled, and the iterator pointer is returned to the caller. | |
7a8e76a3 | 3338 | * |
72c9ddfd DM |
3339 | * Disabling buffer recordng prevents the reading from being |
3340 | * corrupted. This is not a consuming read, so a producer is not | |
3341 | * expected. | |
3342 | * | |
3343 | * After a sequence of ring_buffer_read_prepare calls, the user is | |
3344 | * expected to make at least one call to ring_buffer_prepare_sync. | |
3345 | * Afterwards, ring_buffer_read_start is invoked to get things going | |
3346 | * for real. | |
3347 | * | |
3348 | * This overall must be paired with ring_buffer_finish. | |
7a8e76a3 SR |
3349 | */ |
3350 | struct ring_buffer_iter * | |
72c9ddfd | 3351 | ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu) |
7a8e76a3 SR |
3352 | { |
3353 | struct ring_buffer_per_cpu *cpu_buffer; | |
8aabee57 | 3354 | struct ring_buffer_iter *iter; |
7a8e76a3 | 3355 | |
9e01c1b7 | 3356 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 3357 | return NULL; |
7a8e76a3 SR |
3358 | |
3359 | iter = kmalloc(sizeof(*iter), GFP_KERNEL); | |
3360 | if (!iter) | |
8aabee57 | 3361 | return NULL; |
7a8e76a3 SR |
3362 | |
3363 | cpu_buffer = buffer->buffers[cpu]; | |
3364 | ||
3365 | iter->cpu_buffer = cpu_buffer; | |
3366 | ||
3367 | atomic_inc(&cpu_buffer->record_disabled); | |
72c9ddfd DM |
3368 | |
3369 | return iter; | |
3370 | } | |
3371 | EXPORT_SYMBOL_GPL(ring_buffer_read_prepare); | |
3372 | ||
3373 | /** | |
3374 | * ring_buffer_read_prepare_sync - Synchronize a set of prepare calls | |
3375 | * | |
3376 | * All previously invoked ring_buffer_read_prepare calls to prepare | |
3377 | * iterators will be synchronized. Afterwards, read_buffer_read_start | |
3378 | * calls on those iterators are allowed. | |
3379 | */ | |
3380 | void | |
3381 | ring_buffer_read_prepare_sync(void) | |
3382 | { | |
7a8e76a3 | 3383 | synchronize_sched(); |
72c9ddfd DM |
3384 | } |
3385 | EXPORT_SYMBOL_GPL(ring_buffer_read_prepare_sync); | |
3386 | ||
3387 | /** | |
3388 | * ring_buffer_read_start - start a non consuming read of the buffer | |
3389 | * @iter: The iterator returned by ring_buffer_read_prepare | |
3390 | * | |
3391 | * This finalizes the startup of an iteration through the buffer. | |
3392 | * The iterator comes from a call to ring_buffer_read_prepare and | |
3393 | * an intervening ring_buffer_read_prepare_sync must have been | |
3394 | * performed. | |
3395 | * | |
3396 | * Must be paired with ring_buffer_finish. | |
3397 | */ | |
3398 | void | |
3399 | ring_buffer_read_start(struct ring_buffer_iter *iter) | |
3400 | { | |
3401 | struct ring_buffer_per_cpu *cpu_buffer; | |
3402 | unsigned long flags; | |
3403 | ||
3404 | if (!iter) | |
3405 | return; | |
3406 | ||
3407 | cpu_buffer = iter->cpu_buffer; | |
7a8e76a3 | 3408 | |
f83c9d0f | 3409 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
0199c4e6 | 3410 | arch_spin_lock(&cpu_buffer->lock); |
642edba5 | 3411 | rb_iter_reset(iter); |
0199c4e6 | 3412 | arch_spin_unlock(&cpu_buffer->lock); |
f83c9d0f | 3413 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
7a8e76a3 | 3414 | } |
c4f50183 | 3415 | EXPORT_SYMBOL_GPL(ring_buffer_read_start); |
7a8e76a3 SR |
3416 | |
3417 | /** | |
3418 | * ring_buffer_finish - finish reading the iterator of the buffer | |
3419 | * @iter: The iterator retrieved by ring_buffer_start | |
3420 | * | |
3421 | * This re-enables the recording to the buffer, and frees the | |
3422 | * iterator. | |
3423 | */ | |
3424 | void | |
3425 | ring_buffer_read_finish(struct ring_buffer_iter *iter) | |
3426 | { | |
3427 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
3428 | ||
3429 | atomic_dec(&cpu_buffer->record_disabled); | |
3430 | kfree(iter); | |
3431 | } | |
c4f50183 | 3432 | EXPORT_SYMBOL_GPL(ring_buffer_read_finish); |
7a8e76a3 SR |
3433 | |
3434 | /** | |
3435 | * ring_buffer_read - read the next item in the ring buffer by the iterator | |
3436 | * @iter: The ring buffer iterator | |
3437 | * @ts: The time stamp of the event read. | |
3438 | * | |
3439 | * This reads the next event in the ring buffer and increments the iterator. | |
3440 | */ | |
3441 | struct ring_buffer_event * | |
3442 | ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) | |
3443 | { | |
3444 | struct ring_buffer_event *event; | |
f83c9d0f SR |
3445 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
3446 | unsigned long flags; | |
7a8e76a3 | 3447 | |
f83c9d0f | 3448 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
7e9391cf | 3449 | again: |
f83c9d0f | 3450 | event = rb_iter_peek(iter, ts); |
7a8e76a3 | 3451 | if (!event) |
f83c9d0f | 3452 | goto out; |
7a8e76a3 | 3453 | |
7e9391cf SR |
3454 | if (event->type_len == RINGBUF_TYPE_PADDING) |
3455 | goto again; | |
3456 | ||
7a8e76a3 | 3457 | rb_advance_iter(iter); |
f83c9d0f SR |
3458 | out: |
3459 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
7a8e76a3 SR |
3460 | |
3461 | return event; | |
3462 | } | |
c4f50183 | 3463 | EXPORT_SYMBOL_GPL(ring_buffer_read); |
7a8e76a3 SR |
3464 | |
3465 | /** | |
3466 | * ring_buffer_size - return the size of the ring buffer (in bytes) | |
3467 | * @buffer: The ring buffer. | |
3468 | */ | |
3469 | unsigned long ring_buffer_size(struct ring_buffer *buffer) | |
3470 | { | |
3471 | return BUF_PAGE_SIZE * buffer->pages; | |
3472 | } | |
c4f50183 | 3473 | EXPORT_SYMBOL_GPL(ring_buffer_size); |
7a8e76a3 SR |
3474 | |
3475 | static void | |
3476 | rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) | |
3477 | { | |
77ae365e SR |
3478 | rb_head_page_deactivate(cpu_buffer); |
3479 | ||
7a8e76a3 | 3480 | cpu_buffer->head_page |
3adc54fa | 3481 | = list_entry(cpu_buffer->pages, struct buffer_page, list); |
bf41a158 | 3482 | local_set(&cpu_buffer->head_page->write, 0); |
778c55d4 | 3483 | local_set(&cpu_buffer->head_page->entries, 0); |
abc9b56d | 3484 | local_set(&cpu_buffer->head_page->page->commit, 0); |
d769041f | 3485 | |
6f807acd | 3486 | cpu_buffer->head_page->read = 0; |
bf41a158 SR |
3487 | |
3488 | cpu_buffer->tail_page = cpu_buffer->head_page; | |
3489 | cpu_buffer->commit_page = cpu_buffer->head_page; | |
3490 | ||
3491 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); | |
3492 | local_set(&cpu_buffer->reader_page->write, 0); | |
778c55d4 | 3493 | local_set(&cpu_buffer->reader_page->entries, 0); |
abc9b56d | 3494 | local_set(&cpu_buffer->reader_page->page->commit, 0); |
6f807acd | 3495 | cpu_buffer->reader_page->read = 0; |
7a8e76a3 | 3496 | |
77ae365e SR |
3497 | local_set(&cpu_buffer->commit_overrun, 0); |
3498 | local_set(&cpu_buffer->overrun, 0); | |
e4906eff | 3499 | local_set(&cpu_buffer->entries, 0); |
fa743953 SR |
3500 | local_set(&cpu_buffer->committing, 0); |
3501 | local_set(&cpu_buffer->commits, 0); | |
77ae365e | 3502 | cpu_buffer->read = 0; |
69507c06 SR |
3503 | |
3504 | cpu_buffer->write_stamp = 0; | |
3505 | cpu_buffer->read_stamp = 0; | |
77ae365e | 3506 | |
66a8cb95 SR |
3507 | cpu_buffer->lost_events = 0; |
3508 | cpu_buffer->last_overrun = 0; | |
3509 | ||
77ae365e | 3510 | rb_head_page_activate(cpu_buffer); |
7a8e76a3 SR |
3511 | } |
3512 | ||
3513 | /** | |
3514 | * ring_buffer_reset_cpu - reset a ring buffer per CPU buffer | |
3515 | * @buffer: The ring buffer to reset a per cpu buffer of | |
3516 | * @cpu: The CPU buffer to be reset | |
3517 | */ | |
3518 | void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) | |
3519 | { | |
3520 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
3521 | unsigned long flags; | |
3522 | ||
9e01c1b7 | 3523 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 3524 | return; |
7a8e76a3 | 3525 | |
41ede23e SR |
3526 | atomic_inc(&cpu_buffer->record_disabled); |
3527 | ||
f83c9d0f SR |
3528 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
3529 | ||
41b6a95d SR |
3530 | if (RB_WARN_ON(cpu_buffer, local_read(&cpu_buffer->committing))) |
3531 | goto out; | |
3532 | ||
0199c4e6 | 3533 | arch_spin_lock(&cpu_buffer->lock); |
7a8e76a3 SR |
3534 | |
3535 | rb_reset_cpu(cpu_buffer); | |
3536 | ||
0199c4e6 | 3537 | arch_spin_unlock(&cpu_buffer->lock); |
f83c9d0f | 3538 | |
41b6a95d | 3539 | out: |
f83c9d0f | 3540 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
41ede23e SR |
3541 | |
3542 | atomic_dec(&cpu_buffer->record_disabled); | |
7a8e76a3 | 3543 | } |
c4f50183 | 3544 | EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); |
7a8e76a3 SR |
3545 | |
3546 | /** | |
3547 | * ring_buffer_reset - reset a ring buffer | |
3548 | * @buffer: The ring buffer to reset all cpu buffers | |
3549 | */ | |
3550 | void ring_buffer_reset(struct ring_buffer *buffer) | |
3551 | { | |
7a8e76a3 SR |
3552 | int cpu; |
3553 | ||
7a8e76a3 | 3554 | for_each_buffer_cpu(buffer, cpu) |
d769041f | 3555 | ring_buffer_reset_cpu(buffer, cpu); |
7a8e76a3 | 3556 | } |
c4f50183 | 3557 | EXPORT_SYMBOL_GPL(ring_buffer_reset); |
7a8e76a3 SR |
3558 | |
3559 | /** | |
3560 | * rind_buffer_empty - is the ring buffer empty? | |
3561 | * @buffer: The ring buffer to test | |
3562 | */ | |
3563 | int ring_buffer_empty(struct ring_buffer *buffer) | |
3564 | { | |
3565 | struct ring_buffer_per_cpu *cpu_buffer; | |
d4788207 | 3566 | unsigned long flags; |
8d707e8e | 3567 | int dolock; |
7a8e76a3 | 3568 | int cpu; |
d4788207 | 3569 | int ret; |
7a8e76a3 | 3570 | |
8d707e8e | 3571 | dolock = rb_ok_to_lock(); |
7a8e76a3 SR |
3572 | |
3573 | /* yes this is racy, but if you don't like the race, lock the buffer */ | |
3574 | for_each_buffer_cpu(buffer, cpu) { | |
3575 | cpu_buffer = buffer->buffers[cpu]; | |
8d707e8e SR |
3576 | local_irq_save(flags); |
3577 | if (dolock) | |
3578 | spin_lock(&cpu_buffer->reader_lock); | |
d4788207 | 3579 | ret = rb_per_cpu_empty(cpu_buffer); |
8d707e8e SR |
3580 | if (dolock) |
3581 | spin_unlock(&cpu_buffer->reader_lock); | |
3582 | local_irq_restore(flags); | |
3583 | ||
d4788207 | 3584 | if (!ret) |
7a8e76a3 SR |
3585 | return 0; |
3586 | } | |
554f786e | 3587 | |
7a8e76a3 SR |
3588 | return 1; |
3589 | } | |
c4f50183 | 3590 | EXPORT_SYMBOL_GPL(ring_buffer_empty); |
7a8e76a3 SR |
3591 | |
3592 | /** | |
3593 | * ring_buffer_empty_cpu - is a cpu buffer of a ring buffer empty? | |
3594 | * @buffer: The ring buffer | |
3595 | * @cpu: The CPU buffer to test | |
3596 | */ | |
3597 | int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) | |
3598 | { | |
3599 | struct ring_buffer_per_cpu *cpu_buffer; | |
d4788207 | 3600 | unsigned long flags; |
8d707e8e | 3601 | int dolock; |
8aabee57 | 3602 | int ret; |
7a8e76a3 | 3603 | |
9e01c1b7 | 3604 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 3605 | return 1; |
7a8e76a3 | 3606 | |
8d707e8e SR |
3607 | dolock = rb_ok_to_lock(); |
3608 | ||
7a8e76a3 | 3609 | cpu_buffer = buffer->buffers[cpu]; |
8d707e8e SR |
3610 | local_irq_save(flags); |
3611 | if (dolock) | |
3612 | spin_lock(&cpu_buffer->reader_lock); | |
554f786e | 3613 | ret = rb_per_cpu_empty(cpu_buffer); |
8d707e8e SR |
3614 | if (dolock) |
3615 | spin_unlock(&cpu_buffer->reader_lock); | |
3616 | local_irq_restore(flags); | |
554f786e SR |
3617 | |
3618 | return ret; | |
7a8e76a3 | 3619 | } |
c4f50183 | 3620 | EXPORT_SYMBOL_GPL(ring_buffer_empty_cpu); |
7a8e76a3 | 3621 | |
85bac32c | 3622 | #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP |
7a8e76a3 SR |
3623 | /** |
3624 | * ring_buffer_swap_cpu - swap a CPU buffer between two ring buffers | |
3625 | * @buffer_a: One buffer to swap with | |
3626 | * @buffer_b: The other buffer to swap with | |
3627 | * | |
3628 | * This function is useful for tracers that want to take a "snapshot" | |
3629 | * of a CPU buffer and has another back up buffer lying around. | |
3630 | * it is expected that the tracer handles the cpu buffer not being | |
3631 | * used at the moment. | |
3632 | */ | |
3633 | int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, | |
3634 | struct ring_buffer *buffer_b, int cpu) | |
3635 | { | |
3636 | struct ring_buffer_per_cpu *cpu_buffer_a; | |
3637 | struct ring_buffer_per_cpu *cpu_buffer_b; | |
554f786e SR |
3638 | int ret = -EINVAL; |
3639 | ||
9e01c1b7 RR |
3640 | if (!cpumask_test_cpu(cpu, buffer_a->cpumask) || |
3641 | !cpumask_test_cpu(cpu, buffer_b->cpumask)) | |
554f786e | 3642 | goto out; |
7a8e76a3 SR |
3643 | |
3644 | /* At least make sure the two buffers are somewhat the same */ | |
6d102bc6 | 3645 | if (buffer_a->pages != buffer_b->pages) |
554f786e SR |
3646 | goto out; |
3647 | ||
3648 | ret = -EAGAIN; | |
7a8e76a3 | 3649 | |
97b17efe | 3650 | if (ring_buffer_flags != RB_BUFFERS_ON) |
554f786e | 3651 | goto out; |
97b17efe SR |
3652 | |
3653 | if (atomic_read(&buffer_a->record_disabled)) | |
554f786e | 3654 | goto out; |
97b17efe SR |
3655 | |
3656 | if (atomic_read(&buffer_b->record_disabled)) | |
554f786e | 3657 | goto out; |
97b17efe | 3658 | |
7a8e76a3 SR |
3659 | cpu_buffer_a = buffer_a->buffers[cpu]; |
3660 | cpu_buffer_b = buffer_b->buffers[cpu]; | |
3661 | ||
97b17efe | 3662 | if (atomic_read(&cpu_buffer_a->record_disabled)) |
554f786e | 3663 | goto out; |
97b17efe SR |
3664 | |
3665 | if (atomic_read(&cpu_buffer_b->record_disabled)) | |
554f786e | 3666 | goto out; |
97b17efe | 3667 | |
7a8e76a3 SR |
3668 | /* |
3669 | * We can't do a synchronize_sched here because this | |
3670 | * function can be called in atomic context. | |
3671 | * Normally this will be called from the same CPU as cpu. | |
3672 | * If not it's up to the caller to protect this. | |
3673 | */ | |
3674 | atomic_inc(&cpu_buffer_a->record_disabled); | |
3675 | atomic_inc(&cpu_buffer_b->record_disabled); | |
3676 | ||
98277991 SR |
3677 | ret = -EBUSY; |
3678 | if (local_read(&cpu_buffer_a->committing)) | |
3679 | goto out_dec; | |
3680 | if (local_read(&cpu_buffer_b->committing)) | |
3681 | goto out_dec; | |
3682 | ||
7a8e76a3 SR |
3683 | buffer_a->buffers[cpu] = cpu_buffer_b; |
3684 | buffer_b->buffers[cpu] = cpu_buffer_a; | |
3685 | ||
3686 | cpu_buffer_b->buffer = buffer_a; | |
3687 | cpu_buffer_a->buffer = buffer_b; | |
3688 | ||
98277991 SR |
3689 | ret = 0; |
3690 | ||
3691 | out_dec: | |
7a8e76a3 SR |
3692 | atomic_dec(&cpu_buffer_a->record_disabled); |
3693 | atomic_dec(&cpu_buffer_b->record_disabled); | |
554f786e | 3694 | out: |
554f786e | 3695 | return ret; |
7a8e76a3 | 3696 | } |
c4f50183 | 3697 | EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu); |
85bac32c | 3698 | #endif /* CONFIG_RING_BUFFER_ALLOW_SWAP */ |
7a8e76a3 | 3699 | |
8789a9e7 SR |
3700 | /** |
3701 | * ring_buffer_alloc_read_page - allocate a page to read from buffer | |
3702 | * @buffer: the buffer to allocate for. | |
3703 | * | |
3704 | * This function is used in conjunction with ring_buffer_read_page. | |
3705 | * When reading a full page from the ring buffer, these functions | |
3706 | * can be used to speed up the process. The calling function should | |
3707 | * allocate a few pages first with this function. Then when it | |
3708 | * needs to get pages from the ring buffer, it passes the result | |
3709 | * of this function into ring_buffer_read_page, which will swap | |
3710 | * the page that was allocated, with the read page of the buffer. | |
3711 | * | |
3712 | * Returns: | |
3713 | * The page allocated, or NULL on error. | |
3714 | */ | |
3715 | void *ring_buffer_alloc_read_page(struct ring_buffer *buffer) | |
3716 | { | |
044fa782 | 3717 | struct buffer_data_page *bpage; |
ef7a4a16 | 3718 | unsigned long addr; |
8789a9e7 SR |
3719 | |
3720 | addr = __get_free_page(GFP_KERNEL); | |
3721 | if (!addr) | |
3722 | return NULL; | |
3723 | ||
044fa782 | 3724 | bpage = (void *)addr; |
8789a9e7 | 3725 | |
ef7a4a16 SR |
3726 | rb_init_page(bpage); |
3727 | ||
044fa782 | 3728 | return bpage; |
8789a9e7 | 3729 | } |
d6ce96da | 3730 | EXPORT_SYMBOL_GPL(ring_buffer_alloc_read_page); |
8789a9e7 SR |
3731 | |
3732 | /** | |
3733 | * ring_buffer_free_read_page - free an allocated read page | |
3734 | * @buffer: the buffer the page was allocate for | |
3735 | * @data: the page to free | |
3736 | * | |
3737 | * Free a page allocated from ring_buffer_alloc_read_page. | |
3738 | */ | |
3739 | void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data) | |
3740 | { | |
3741 | free_page((unsigned long)data); | |
3742 | } | |
d6ce96da | 3743 | EXPORT_SYMBOL_GPL(ring_buffer_free_read_page); |
8789a9e7 SR |
3744 | |
3745 | /** | |
3746 | * ring_buffer_read_page - extract a page from the ring buffer | |
3747 | * @buffer: buffer to extract from | |
3748 | * @data_page: the page to use allocated from ring_buffer_alloc_read_page | |
ef7a4a16 | 3749 | * @len: amount to extract |
8789a9e7 SR |
3750 | * @cpu: the cpu of the buffer to extract |
3751 | * @full: should the extraction only happen when the page is full. | |
3752 | * | |
3753 | * This function will pull out a page from the ring buffer and consume it. | |
3754 | * @data_page must be the address of the variable that was returned | |
3755 | * from ring_buffer_alloc_read_page. This is because the page might be used | |
3756 | * to swap with a page in the ring buffer. | |
3757 | * | |
3758 | * for example: | |
b85fa01e | 3759 | * rpage = ring_buffer_alloc_read_page(buffer); |
8789a9e7 SR |
3760 | * if (!rpage) |
3761 | * return error; | |
ef7a4a16 | 3762 | * ret = ring_buffer_read_page(buffer, &rpage, len, cpu, 0); |
667d2412 LJ |
3763 | * if (ret >= 0) |
3764 | * process_page(rpage, ret); | |
8789a9e7 SR |
3765 | * |
3766 | * When @full is set, the function will not return true unless | |
3767 | * the writer is off the reader page. | |
3768 | * | |
3769 | * Note: it is up to the calling functions to handle sleeps and wakeups. | |
3770 | * The ring buffer can be used anywhere in the kernel and can not | |
3771 | * blindly call wake_up. The layer that uses the ring buffer must be | |
3772 | * responsible for that. | |
3773 | * | |
3774 | * Returns: | |
667d2412 LJ |
3775 | * >=0 if data has been transferred, returns the offset of consumed data. |
3776 | * <0 if no data has been transferred. | |
8789a9e7 SR |
3777 | */ |
3778 | int ring_buffer_read_page(struct ring_buffer *buffer, | |
ef7a4a16 | 3779 | void **data_page, size_t len, int cpu, int full) |
8789a9e7 SR |
3780 | { |
3781 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
3782 | struct ring_buffer_event *event; | |
044fa782 | 3783 | struct buffer_data_page *bpage; |
ef7a4a16 | 3784 | struct buffer_page *reader; |
ff0ff84a | 3785 | unsigned long missed_events; |
8789a9e7 | 3786 | unsigned long flags; |
ef7a4a16 | 3787 | unsigned int commit; |
667d2412 | 3788 | unsigned int read; |
4f3640f8 | 3789 | u64 save_timestamp; |
667d2412 | 3790 | int ret = -1; |
8789a9e7 | 3791 | |
554f786e SR |
3792 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
3793 | goto out; | |
3794 | ||
474d32b6 SR |
3795 | /* |
3796 | * If len is not big enough to hold the page header, then | |
3797 | * we can not copy anything. | |
3798 | */ | |
3799 | if (len <= BUF_PAGE_HDR_SIZE) | |
554f786e | 3800 | goto out; |
474d32b6 SR |
3801 | |
3802 | len -= BUF_PAGE_HDR_SIZE; | |
3803 | ||
8789a9e7 | 3804 | if (!data_page) |
554f786e | 3805 | goto out; |
8789a9e7 | 3806 | |
044fa782 SR |
3807 | bpage = *data_page; |
3808 | if (!bpage) | |
554f786e | 3809 | goto out; |
8789a9e7 SR |
3810 | |
3811 | spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
3812 | ||
ef7a4a16 SR |
3813 | reader = rb_get_reader_page(cpu_buffer); |
3814 | if (!reader) | |
554f786e | 3815 | goto out_unlock; |
8789a9e7 | 3816 | |
ef7a4a16 SR |
3817 | event = rb_reader_event(cpu_buffer); |
3818 | ||
3819 | read = reader->read; | |
3820 | commit = rb_page_commit(reader); | |
667d2412 | 3821 | |
66a8cb95 | 3822 | /* Check if any events were dropped */ |
ff0ff84a | 3823 | missed_events = cpu_buffer->lost_events; |
66a8cb95 | 3824 | |
8789a9e7 | 3825 | /* |
474d32b6 SR |
3826 | * If this page has been partially read or |
3827 | * if len is not big enough to read the rest of the page or | |
3828 | * a writer is still on the page, then | |
3829 | * we must copy the data from the page to the buffer. | |
3830 | * Otherwise, we can simply swap the page with the one passed in. | |
8789a9e7 | 3831 | */ |
474d32b6 | 3832 | if (read || (len < (commit - read)) || |
ef7a4a16 | 3833 | cpu_buffer->reader_page == cpu_buffer->commit_page) { |
667d2412 | 3834 | struct buffer_data_page *rpage = cpu_buffer->reader_page->page; |
474d32b6 SR |
3835 | unsigned int rpos = read; |
3836 | unsigned int pos = 0; | |
ef7a4a16 | 3837 | unsigned int size; |
8789a9e7 SR |
3838 | |
3839 | if (full) | |
554f786e | 3840 | goto out_unlock; |
8789a9e7 | 3841 | |
ef7a4a16 SR |
3842 | if (len > (commit - read)) |
3843 | len = (commit - read); | |
3844 | ||
69d1b839 SR |
3845 | /* Always keep the time extend and data together */ |
3846 | size = rb_event_ts_length(event); | |
ef7a4a16 SR |
3847 | |
3848 | if (len < size) | |
554f786e | 3849 | goto out_unlock; |
ef7a4a16 | 3850 | |
4f3640f8 SR |
3851 | /* save the current timestamp, since the user will need it */ |
3852 | save_timestamp = cpu_buffer->read_stamp; | |
3853 | ||
ef7a4a16 SR |
3854 | /* Need to copy one event at a time */ |
3855 | do { | |
e1e35927 DS |
3856 | /* We need the size of one event, because |
3857 | * rb_advance_reader only advances by one event, | |
3858 | * whereas rb_event_ts_length may include the size of | |
3859 | * one or two events. | |
3860 | * We have already ensured there's enough space if this | |
3861 | * is a time extend. */ | |
3862 | size = rb_event_length(event); | |
474d32b6 | 3863 | memcpy(bpage->data + pos, rpage->data + rpos, size); |
ef7a4a16 SR |
3864 | |
3865 | len -= size; | |
3866 | ||
3867 | rb_advance_reader(cpu_buffer); | |
474d32b6 SR |
3868 | rpos = reader->read; |
3869 | pos += size; | |
ef7a4a16 | 3870 | |
18fab912 HY |
3871 | if (rpos >= commit) |
3872 | break; | |
3873 | ||
ef7a4a16 | 3874 | event = rb_reader_event(cpu_buffer); |
69d1b839 SR |
3875 | /* Always keep the time extend and data together */ |
3876 | size = rb_event_ts_length(event); | |
e1e35927 | 3877 | } while (len >= size); |
667d2412 LJ |
3878 | |
3879 | /* update bpage */ | |
ef7a4a16 | 3880 | local_set(&bpage->commit, pos); |
4f3640f8 | 3881 | bpage->time_stamp = save_timestamp; |
ef7a4a16 | 3882 | |
474d32b6 SR |
3883 | /* we copied everything to the beginning */ |
3884 | read = 0; | |
8789a9e7 | 3885 | } else { |
afbab76a | 3886 | /* update the entry counter */ |
77ae365e | 3887 | cpu_buffer->read += rb_page_entries(reader); |
afbab76a | 3888 | |
8789a9e7 | 3889 | /* swap the pages */ |
044fa782 | 3890 | rb_init_page(bpage); |
ef7a4a16 SR |
3891 | bpage = reader->page; |
3892 | reader->page = *data_page; | |
3893 | local_set(&reader->write, 0); | |
778c55d4 | 3894 | local_set(&reader->entries, 0); |
ef7a4a16 | 3895 | reader->read = 0; |
044fa782 | 3896 | *data_page = bpage; |
ff0ff84a SR |
3897 | |
3898 | /* | |
3899 | * Use the real_end for the data size, | |
3900 | * This gives us a chance to store the lost events | |
3901 | * on the page. | |
3902 | */ | |
3903 | if (reader->real_end) | |
3904 | local_set(&bpage->commit, reader->real_end); | |
8789a9e7 | 3905 | } |
667d2412 | 3906 | ret = read; |
8789a9e7 | 3907 | |
66a8cb95 | 3908 | cpu_buffer->lost_events = 0; |
2711ca23 SR |
3909 | |
3910 | commit = local_read(&bpage->commit); | |
66a8cb95 SR |
3911 | /* |
3912 | * Set a flag in the commit field if we lost events | |
3913 | */ | |
ff0ff84a | 3914 | if (missed_events) { |
ff0ff84a SR |
3915 | /* If there is room at the end of the page to save the |
3916 | * missed events, then record it there. | |
3917 | */ | |
3918 | if (BUF_PAGE_SIZE - commit >= sizeof(missed_events)) { | |
3919 | memcpy(&bpage->data[commit], &missed_events, | |
3920 | sizeof(missed_events)); | |
3921 | local_add(RB_MISSED_STORED, &bpage->commit); | |
2711ca23 | 3922 | commit += sizeof(missed_events); |
ff0ff84a | 3923 | } |
66a8cb95 | 3924 | local_add(RB_MISSED_EVENTS, &bpage->commit); |
ff0ff84a | 3925 | } |
66a8cb95 | 3926 | |
2711ca23 SR |
3927 | /* |
3928 | * This page may be off to user land. Zero it out here. | |
3929 | */ | |
3930 | if (commit < BUF_PAGE_SIZE) | |
3931 | memset(&bpage->data[commit], 0, BUF_PAGE_SIZE - commit); | |
3932 | ||
554f786e | 3933 | out_unlock: |
8789a9e7 SR |
3934 | spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
3935 | ||
554f786e | 3936 | out: |
8789a9e7 SR |
3937 | return ret; |
3938 | } | |
d6ce96da | 3939 | EXPORT_SYMBOL_GPL(ring_buffer_read_page); |
8789a9e7 | 3940 | |
1155de47 | 3941 | #ifdef CONFIG_TRACING |
a3583244 SR |
3942 | static ssize_t |
3943 | rb_simple_read(struct file *filp, char __user *ubuf, | |
3944 | size_t cnt, loff_t *ppos) | |
3945 | { | |
5e39841c | 3946 | unsigned long *p = filp->private_data; |
a3583244 SR |
3947 | char buf[64]; |
3948 | int r; | |
3949 | ||
033601a3 SR |
3950 | if (test_bit(RB_BUFFERS_DISABLED_BIT, p)) |
3951 | r = sprintf(buf, "permanently disabled\n"); | |
3952 | else | |
3953 | r = sprintf(buf, "%d\n", test_bit(RB_BUFFERS_ON_BIT, p)); | |
a3583244 SR |
3954 | |
3955 | return simple_read_from_buffer(ubuf, cnt, ppos, buf, r); | |
3956 | } | |
3957 | ||
3958 | static ssize_t | |
3959 | rb_simple_write(struct file *filp, const char __user *ubuf, | |
3960 | size_t cnt, loff_t *ppos) | |
3961 | { | |
5e39841c | 3962 | unsigned long *p = filp->private_data; |
a3583244 | 3963 | char buf[64]; |
5e39841c | 3964 | unsigned long val; |
a3583244 SR |
3965 | int ret; |
3966 | ||
3967 | if (cnt >= sizeof(buf)) | |
3968 | return -EINVAL; | |
3969 | ||
3970 | if (copy_from_user(&buf, ubuf, cnt)) | |
3971 | return -EFAULT; | |
3972 | ||
3973 | buf[cnt] = 0; | |
3974 | ||
3975 | ret = strict_strtoul(buf, 10, &val); | |
3976 | if (ret < 0) | |
3977 | return ret; | |
3978 | ||
033601a3 SR |
3979 | if (val) |
3980 | set_bit(RB_BUFFERS_ON_BIT, p); | |
3981 | else | |
3982 | clear_bit(RB_BUFFERS_ON_BIT, p); | |
a3583244 SR |
3983 | |
3984 | (*ppos)++; | |
3985 | ||
3986 | return cnt; | |
3987 | } | |
3988 | ||
5e2336a0 | 3989 | static const struct file_operations rb_simple_fops = { |
a3583244 SR |
3990 | .open = tracing_open_generic, |
3991 | .read = rb_simple_read, | |
3992 | .write = rb_simple_write, | |
6038f373 | 3993 | .llseek = default_llseek, |
a3583244 SR |
3994 | }; |
3995 | ||
3996 | ||
3997 | static __init int rb_init_debugfs(void) | |
3998 | { | |
3999 | struct dentry *d_tracer; | |
a3583244 SR |
4000 | |
4001 | d_tracer = tracing_init_dentry(); | |
4002 | ||
5452af66 FW |
4003 | trace_create_file("tracing_on", 0644, d_tracer, |
4004 | &ring_buffer_flags, &rb_simple_fops); | |
a3583244 SR |
4005 | |
4006 | return 0; | |
4007 | } | |
4008 | ||
4009 | fs_initcall(rb_init_debugfs); | |
1155de47 | 4010 | #endif |
554f786e | 4011 | |
59222efe | 4012 | #ifdef CONFIG_HOTPLUG_CPU |
09c9e84d FW |
4013 | static int rb_cpu_notify(struct notifier_block *self, |
4014 | unsigned long action, void *hcpu) | |
554f786e SR |
4015 | { |
4016 | struct ring_buffer *buffer = | |
4017 | container_of(self, struct ring_buffer, cpu_notify); | |
4018 | long cpu = (long)hcpu; | |
4019 | ||
4020 | switch (action) { | |
4021 | case CPU_UP_PREPARE: | |
4022 | case CPU_UP_PREPARE_FROZEN: | |
3f237a79 | 4023 | if (cpumask_test_cpu(cpu, buffer->cpumask)) |
554f786e SR |
4024 | return NOTIFY_OK; |
4025 | ||
4026 | buffer->buffers[cpu] = | |
4027 | rb_allocate_cpu_buffer(buffer, cpu); | |
4028 | if (!buffer->buffers[cpu]) { | |
4029 | WARN(1, "failed to allocate ring buffer on CPU %ld\n", | |
4030 | cpu); | |
4031 | return NOTIFY_OK; | |
4032 | } | |
4033 | smp_wmb(); | |
3f237a79 | 4034 | cpumask_set_cpu(cpu, buffer->cpumask); |
554f786e SR |
4035 | break; |
4036 | case CPU_DOWN_PREPARE: | |
4037 | case CPU_DOWN_PREPARE_FROZEN: | |
4038 | /* | |
4039 | * Do nothing. | |
4040 | * If we were to free the buffer, then the user would | |
4041 | * lose any trace that was in the buffer. | |
4042 | */ | |
4043 | break; | |
4044 | default: | |
4045 | break; | |
4046 | } | |
4047 | return NOTIFY_OK; | |
4048 | } | |
4049 | #endif |