Commit | Line | Data |
---|---|---|
7a8e76a3 SR |
1 | /* |
2 | * Generic ring buffer | |
3 | * | |
4 | * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com> | |
5 | */ | |
0b07436d | 6 | #include <linux/ftrace_event.h> |
7a8e76a3 | 7 | #include <linux/ring_buffer.h> |
14131f2f | 8 | #include <linux/trace_clock.h> |
0b07436d | 9 | #include <linux/trace_seq.h> |
7a8e76a3 | 10 | #include <linux/spinlock.h> |
15693458 | 11 | #include <linux/irq_work.h> |
7a8e76a3 SR |
12 | #include <linux/debugfs.h> |
13 | #include <linux/uaccess.h> | |
a81bd80a | 14 | #include <linux/hardirq.h> |
6c43e554 | 15 | #include <linux/kthread.h> /* for self test */ |
1744a21d | 16 | #include <linux/kmemcheck.h> |
7a8e76a3 SR |
17 | #include <linux/module.h> |
18 | #include <linux/percpu.h> | |
19 | #include <linux/mutex.h> | |
6c43e554 | 20 | #include <linux/delay.h> |
5a0e3ad6 | 21 | #include <linux/slab.h> |
7a8e76a3 SR |
22 | #include <linux/init.h> |
23 | #include <linux/hash.h> | |
24 | #include <linux/list.h> | |
554f786e | 25 | #include <linux/cpu.h> |
7a8e76a3 SR |
26 | #include <linux/fs.h> |
27 | ||
79615760 | 28 | #include <asm/local.h> |
182e9f5f | 29 | |
83f40318 VN |
30 | static void update_pages_handler(struct work_struct *work); |
31 | ||
d1b182a8 SR |
32 | /* |
33 | * The ring buffer header is special. We must manually up keep it. | |
34 | */ | |
35 | int ring_buffer_print_entry_header(struct trace_seq *s) | |
36 | { | |
37 | int ret; | |
38 | ||
146c3442 J |
39 | ret = trace_seq_puts(s, "# compressed entry header\n"); |
40 | ret = trace_seq_puts(s, "\ttype_len : 5 bits\n"); | |
41 | ret = trace_seq_puts(s, "\ttime_delta : 27 bits\n"); | |
42 | ret = trace_seq_puts(s, "\tarray : 32 bits\n"); | |
43 | ret = trace_seq_putc(s, '\n'); | |
d1b182a8 SR |
44 | ret = trace_seq_printf(s, "\tpadding : type == %d\n", |
45 | RINGBUF_TYPE_PADDING); | |
46 | ret = trace_seq_printf(s, "\ttime_extend : type == %d\n", | |
47 | RINGBUF_TYPE_TIME_EXTEND); | |
334d4169 LJ |
48 | ret = trace_seq_printf(s, "\tdata max type_len == %d\n", |
49 | RINGBUF_TYPE_DATA_TYPE_LEN_MAX); | |
d1b182a8 SR |
50 | |
51 | return ret; | |
52 | } | |
53 | ||
5cc98548 SR |
54 | /* |
55 | * The ring buffer is made up of a list of pages. A separate list of pages is | |
56 | * allocated for each CPU. A writer may only write to a buffer that is | |
57 | * associated with the CPU it is currently executing on. A reader may read | |
58 | * from any per cpu buffer. | |
59 | * | |
60 | * The reader is special. For each per cpu buffer, the reader has its own | |
61 | * reader page. When a reader has read the entire reader page, this reader | |
62 | * page is swapped with another page in the ring buffer. | |
63 | * | |
64 | * Now, as long as the writer is off the reader page, the reader can do what | |
65 | * ever it wants with that page. The writer will never write to that page | |
66 | * again (as long as it is out of the ring buffer). | |
67 | * | |
68 | * Here's some silly ASCII art. | |
69 | * | |
70 | * +------+ | |
71 | * |reader| RING BUFFER | |
72 | * |page | | |
73 | * +------+ +---+ +---+ +---+ | |
74 | * | |-->| |-->| | | |
75 | * +---+ +---+ +---+ | |
76 | * ^ | | |
77 | * | | | |
78 | * +---------------+ | |
79 | * | |
80 | * | |
81 | * +------+ | |
82 | * |reader| RING BUFFER | |
83 | * |page |------------------v | |
84 | * +------+ +---+ +---+ +---+ | |
85 | * | |-->| |-->| | | |
86 | * +---+ +---+ +---+ | |
87 | * ^ | | |
88 | * | | | |
89 | * +---------------+ | |
90 | * | |
91 | * | |
92 | * +------+ | |
93 | * |reader| RING BUFFER | |
94 | * |page |------------------v | |
95 | * +------+ +---+ +---+ +---+ | |
96 | * ^ | |-->| |-->| | | |
97 | * | +---+ +---+ +---+ | |
98 | * | | | |
99 | * | | | |
100 | * +------------------------------+ | |
101 | * | |
102 | * | |
103 | * +------+ | |
104 | * |buffer| RING BUFFER | |
105 | * |page |------------------v | |
106 | * +------+ +---+ +---+ +---+ | |
107 | * ^ | | | |-->| | | |
108 | * | New +---+ +---+ +---+ | |
109 | * | Reader------^ | | |
110 | * | page | | |
111 | * +------------------------------+ | |
112 | * | |
113 | * | |
114 | * After we make this swap, the reader can hand this page off to the splice | |
115 | * code and be done with it. It can even allocate a new page if it needs to | |
116 | * and swap that into the ring buffer. | |
117 | * | |
118 | * We will be using cmpxchg soon to make all this lockless. | |
119 | * | |
120 | */ | |
121 | ||
033601a3 SR |
122 | /* |
123 | * A fast way to enable or disable all ring buffers is to | |
124 | * call tracing_on or tracing_off. Turning off the ring buffers | |
125 | * prevents all ring buffers from being recorded to. | |
126 | * Turning this switch on, makes it OK to write to the | |
127 | * ring buffer, if the ring buffer is enabled itself. | |
128 | * | |
129 | * There's three layers that must be on in order to write | |
130 | * to the ring buffer. | |
131 | * | |
132 | * 1) This global flag must be set. | |
133 | * 2) The ring buffer must be enabled for recording. | |
134 | * 3) The per cpu buffer must be enabled for recording. | |
135 | * | |
136 | * In case of an anomaly, this global flag has a bit set that | |
137 | * will permantly disable all ring buffers. | |
138 | */ | |
139 | ||
140 | /* | |
141 | * Global flag to disable all recording to ring buffers | |
142 | * This has two bits: ON, DISABLED | |
143 | * | |
144 | * ON DISABLED | |
145 | * ---- ---------- | |
146 | * 0 0 : ring buffers are off | |
147 | * 1 0 : ring buffers are on | |
148 | * X 1 : ring buffers are permanently disabled | |
149 | */ | |
150 | ||
151 | enum { | |
152 | RB_BUFFERS_ON_BIT = 0, | |
153 | RB_BUFFERS_DISABLED_BIT = 1, | |
154 | }; | |
155 | ||
156 | enum { | |
157 | RB_BUFFERS_ON = 1 << RB_BUFFERS_ON_BIT, | |
158 | RB_BUFFERS_DISABLED = 1 << RB_BUFFERS_DISABLED_BIT, | |
159 | }; | |
160 | ||
5e39841c | 161 | static unsigned long ring_buffer_flags __read_mostly = RB_BUFFERS_ON; |
a3583244 | 162 | |
499e5470 SR |
163 | /* Used for individual buffers (after the counter) */ |
164 | #define RB_BUFFER_OFF (1 << 20) | |
a3583244 | 165 | |
499e5470 | 166 | #define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data) |
033601a3 SR |
167 | |
168 | /** | |
169 | * tracing_off_permanent - permanently disable ring buffers | |
170 | * | |
171 | * This function, once called, will disable all ring buffers | |
c3706f00 | 172 | * permanently. |
033601a3 SR |
173 | */ |
174 | void tracing_off_permanent(void) | |
175 | { | |
176 | set_bit(RB_BUFFERS_DISABLED_BIT, &ring_buffer_flags); | |
a3583244 SR |
177 | } |
178 | ||
e3d6bf0a | 179 | #define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array)) |
67d34724 | 180 | #define RB_ALIGNMENT 4U |
334d4169 | 181 | #define RB_MAX_SMALL_DATA (RB_ALIGNMENT * RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
c7b09308 | 182 | #define RB_EVNT_MIN_SIZE 8U /* two 32bit words */ |
334d4169 | 183 | |
649508f6 | 184 | #ifndef CONFIG_HAVE_64BIT_ALIGNED_ACCESS |
2271048d SR |
185 | # define RB_FORCE_8BYTE_ALIGNMENT 0 |
186 | # define RB_ARCH_ALIGNMENT RB_ALIGNMENT | |
187 | #else | |
188 | # define RB_FORCE_8BYTE_ALIGNMENT 1 | |
189 | # define RB_ARCH_ALIGNMENT 8U | |
190 | #endif | |
191 | ||
649508f6 JH |
192 | #define RB_ALIGN_DATA __aligned(RB_ARCH_ALIGNMENT) |
193 | ||
334d4169 LJ |
194 | /* define RINGBUF_TYPE_DATA for 'case RINGBUF_TYPE_DATA:' */ |
195 | #define RINGBUF_TYPE_DATA 0 ... RINGBUF_TYPE_DATA_TYPE_LEN_MAX | |
7a8e76a3 SR |
196 | |
197 | enum { | |
198 | RB_LEN_TIME_EXTEND = 8, | |
199 | RB_LEN_TIME_STAMP = 16, | |
200 | }; | |
201 | ||
69d1b839 SR |
202 | #define skip_time_extend(event) \ |
203 | ((struct ring_buffer_event *)((char *)event + RB_LEN_TIME_EXTEND)) | |
204 | ||
2d622719 TZ |
205 | static inline int rb_null_event(struct ring_buffer_event *event) |
206 | { | |
a1863c21 | 207 | return event->type_len == RINGBUF_TYPE_PADDING && !event->time_delta; |
2d622719 TZ |
208 | } |
209 | ||
210 | static void rb_event_set_padding(struct ring_buffer_event *event) | |
211 | { | |
a1863c21 | 212 | /* padding has a NULL time_delta */ |
334d4169 | 213 | event->type_len = RINGBUF_TYPE_PADDING; |
2d622719 TZ |
214 | event->time_delta = 0; |
215 | } | |
216 | ||
34a148bf | 217 | static unsigned |
2d622719 | 218 | rb_event_data_length(struct ring_buffer_event *event) |
7a8e76a3 SR |
219 | { |
220 | unsigned length; | |
221 | ||
334d4169 LJ |
222 | if (event->type_len) |
223 | length = event->type_len * RB_ALIGNMENT; | |
2d622719 TZ |
224 | else |
225 | length = event->array[0]; | |
226 | return length + RB_EVNT_HDR_SIZE; | |
227 | } | |
228 | ||
69d1b839 SR |
229 | /* |
230 | * Return the length of the given event. Will return | |
231 | * the length of the time extend if the event is a | |
232 | * time extend. | |
233 | */ | |
234 | static inline unsigned | |
2d622719 TZ |
235 | rb_event_length(struct ring_buffer_event *event) |
236 | { | |
334d4169 | 237 | switch (event->type_len) { |
7a8e76a3 | 238 | case RINGBUF_TYPE_PADDING: |
2d622719 TZ |
239 | if (rb_null_event(event)) |
240 | /* undefined */ | |
241 | return -1; | |
334d4169 | 242 | return event->array[0] + RB_EVNT_HDR_SIZE; |
7a8e76a3 SR |
243 | |
244 | case RINGBUF_TYPE_TIME_EXTEND: | |
245 | return RB_LEN_TIME_EXTEND; | |
246 | ||
247 | case RINGBUF_TYPE_TIME_STAMP: | |
248 | return RB_LEN_TIME_STAMP; | |
249 | ||
250 | case RINGBUF_TYPE_DATA: | |
2d622719 | 251 | return rb_event_data_length(event); |
7a8e76a3 SR |
252 | default: |
253 | BUG(); | |
254 | } | |
255 | /* not hit */ | |
256 | return 0; | |
257 | } | |
258 | ||
69d1b839 SR |
259 | /* |
260 | * Return total length of time extend and data, | |
261 | * or just the event length for all other events. | |
262 | */ | |
263 | static inline unsigned | |
264 | rb_event_ts_length(struct ring_buffer_event *event) | |
265 | { | |
266 | unsigned len = 0; | |
267 | ||
268 | if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) { | |
269 | /* time extends include the data event after it */ | |
270 | len = RB_LEN_TIME_EXTEND; | |
271 | event = skip_time_extend(event); | |
272 | } | |
273 | return len + rb_event_length(event); | |
274 | } | |
275 | ||
7a8e76a3 SR |
276 | /** |
277 | * ring_buffer_event_length - return the length of the event | |
278 | * @event: the event to get the length of | |
69d1b839 SR |
279 | * |
280 | * Returns the size of the data load of a data event. | |
281 | * If the event is something other than a data event, it | |
282 | * returns the size of the event itself. With the exception | |
283 | * of a TIME EXTEND, where it still returns the size of the | |
284 | * data load of the data event after it. | |
7a8e76a3 SR |
285 | */ |
286 | unsigned ring_buffer_event_length(struct ring_buffer_event *event) | |
287 | { | |
69d1b839 SR |
288 | unsigned length; |
289 | ||
290 | if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) | |
291 | event = skip_time_extend(event); | |
292 | ||
293 | length = rb_event_length(event); | |
334d4169 | 294 | if (event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
465634ad RR |
295 | return length; |
296 | length -= RB_EVNT_HDR_SIZE; | |
297 | if (length > RB_MAX_SMALL_DATA + sizeof(event->array[0])) | |
298 | length -= sizeof(event->array[0]); | |
299 | return length; | |
7a8e76a3 | 300 | } |
c4f50183 | 301 | EXPORT_SYMBOL_GPL(ring_buffer_event_length); |
7a8e76a3 SR |
302 | |
303 | /* inline for ring buffer fast paths */ | |
34a148bf | 304 | static void * |
7a8e76a3 SR |
305 | rb_event_data(struct ring_buffer_event *event) |
306 | { | |
69d1b839 SR |
307 | if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) |
308 | event = skip_time_extend(event); | |
334d4169 | 309 | BUG_ON(event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX); |
7a8e76a3 | 310 | /* If length is in len field, then array[0] has the data */ |
334d4169 | 311 | if (event->type_len) |
7a8e76a3 SR |
312 | return (void *)&event->array[0]; |
313 | /* Otherwise length is in array[0] and array[1] has the data */ | |
314 | return (void *)&event->array[1]; | |
315 | } | |
316 | ||
317 | /** | |
318 | * ring_buffer_event_data - return the data of the event | |
319 | * @event: the event to get the data from | |
320 | */ | |
321 | void *ring_buffer_event_data(struct ring_buffer_event *event) | |
322 | { | |
323 | return rb_event_data(event); | |
324 | } | |
c4f50183 | 325 | EXPORT_SYMBOL_GPL(ring_buffer_event_data); |
7a8e76a3 SR |
326 | |
327 | #define for_each_buffer_cpu(buffer, cpu) \ | |
9e01c1b7 | 328 | for_each_cpu(cpu, buffer->cpumask) |
7a8e76a3 SR |
329 | |
330 | #define TS_SHIFT 27 | |
331 | #define TS_MASK ((1ULL << TS_SHIFT) - 1) | |
332 | #define TS_DELTA_TEST (~TS_MASK) | |
333 | ||
66a8cb95 SR |
334 | /* Flag when events were overwritten */ |
335 | #define RB_MISSED_EVENTS (1 << 31) | |
ff0ff84a SR |
336 | /* Missed count stored at end */ |
337 | #define RB_MISSED_STORED (1 << 30) | |
66a8cb95 | 338 | |
abc9b56d | 339 | struct buffer_data_page { |
e4c2ce82 | 340 | u64 time_stamp; /* page time stamp */ |
c3706f00 | 341 | local_t commit; /* write committed index */ |
649508f6 | 342 | unsigned char data[] RB_ALIGN_DATA; /* data of buffer page */ |
abc9b56d SR |
343 | }; |
344 | ||
77ae365e SR |
345 | /* |
346 | * Note, the buffer_page list must be first. The buffer pages | |
347 | * are allocated in cache lines, which means that each buffer | |
348 | * page will be at the beginning of a cache line, and thus | |
349 | * the least significant bits will be zero. We use this to | |
350 | * add flags in the list struct pointers, to make the ring buffer | |
351 | * lockless. | |
352 | */ | |
abc9b56d | 353 | struct buffer_page { |
778c55d4 | 354 | struct list_head list; /* list of buffer pages */ |
abc9b56d | 355 | local_t write; /* index for next write */ |
6f807acd | 356 | unsigned read; /* index for next read */ |
778c55d4 | 357 | local_t entries; /* entries on this page */ |
ff0ff84a | 358 | unsigned long real_end; /* real end of data */ |
abc9b56d | 359 | struct buffer_data_page *page; /* Actual data page */ |
7a8e76a3 SR |
360 | }; |
361 | ||
77ae365e SR |
362 | /* |
363 | * The buffer page counters, write and entries, must be reset | |
364 | * atomically when crossing page boundaries. To synchronize this | |
365 | * update, two counters are inserted into the number. One is | |
366 | * the actual counter for the write position or count on the page. | |
367 | * | |
368 | * The other is a counter of updaters. Before an update happens | |
369 | * the update partition of the counter is incremented. This will | |
370 | * allow the updater to update the counter atomically. | |
371 | * | |
372 | * The counter is 20 bits, and the state data is 12. | |
373 | */ | |
374 | #define RB_WRITE_MASK 0xfffff | |
375 | #define RB_WRITE_INTCNT (1 << 20) | |
376 | ||
044fa782 | 377 | static void rb_init_page(struct buffer_data_page *bpage) |
abc9b56d | 378 | { |
044fa782 | 379 | local_set(&bpage->commit, 0); |
abc9b56d SR |
380 | } |
381 | ||
474d32b6 SR |
382 | /** |
383 | * ring_buffer_page_len - the size of data on the page. | |
384 | * @page: The page to read | |
385 | * | |
386 | * Returns the amount of data on the page, including buffer page header. | |
387 | */ | |
ef7a4a16 SR |
388 | size_t ring_buffer_page_len(void *page) |
389 | { | |
474d32b6 SR |
390 | return local_read(&((struct buffer_data_page *)page)->commit) |
391 | + BUF_PAGE_HDR_SIZE; | |
ef7a4a16 SR |
392 | } |
393 | ||
ed56829c SR |
394 | /* |
395 | * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing | |
396 | * this issue out. | |
397 | */ | |
34a148bf | 398 | static void free_buffer_page(struct buffer_page *bpage) |
ed56829c | 399 | { |
34a148bf | 400 | free_page((unsigned long)bpage->page); |
e4c2ce82 | 401 | kfree(bpage); |
ed56829c SR |
402 | } |
403 | ||
7a8e76a3 SR |
404 | /* |
405 | * We need to fit the time_stamp delta into 27 bits. | |
406 | */ | |
407 | static inline int test_time_stamp(u64 delta) | |
408 | { | |
409 | if (delta & TS_DELTA_TEST) | |
410 | return 1; | |
411 | return 0; | |
412 | } | |
413 | ||
474d32b6 | 414 | #define BUF_PAGE_SIZE (PAGE_SIZE - BUF_PAGE_HDR_SIZE) |
7a8e76a3 | 415 | |
be957c44 SR |
416 | /* Max payload is BUF_PAGE_SIZE - header (8bytes) */ |
417 | #define BUF_MAX_DATA_SIZE (BUF_PAGE_SIZE - (sizeof(u32) * 2)) | |
418 | ||
d1b182a8 SR |
419 | int ring_buffer_print_page_header(struct trace_seq *s) |
420 | { | |
421 | struct buffer_data_page field; | |
422 | int ret; | |
423 | ||
424 | ret = trace_seq_printf(s, "\tfield: u64 timestamp;\t" | |
26a50744 TZ |
425 | "offset:0;\tsize:%u;\tsigned:%u;\n", |
426 | (unsigned int)sizeof(field.time_stamp), | |
427 | (unsigned int)is_signed_type(u64)); | |
d1b182a8 SR |
428 | |
429 | ret = trace_seq_printf(s, "\tfield: local_t commit;\t" | |
26a50744 | 430 | "offset:%u;\tsize:%u;\tsigned:%u;\n", |
d1b182a8 | 431 | (unsigned int)offsetof(typeof(field), commit), |
26a50744 TZ |
432 | (unsigned int)sizeof(field.commit), |
433 | (unsigned int)is_signed_type(long)); | |
d1b182a8 | 434 | |
66a8cb95 SR |
435 | ret = trace_seq_printf(s, "\tfield: int overwrite;\t" |
436 | "offset:%u;\tsize:%u;\tsigned:%u;\n", | |
437 | (unsigned int)offsetof(typeof(field), commit), | |
438 | 1, | |
439 | (unsigned int)is_signed_type(long)); | |
440 | ||
d1b182a8 | 441 | ret = trace_seq_printf(s, "\tfield: char data;\t" |
26a50744 | 442 | "offset:%u;\tsize:%u;\tsigned:%u;\n", |
d1b182a8 | 443 | (unsigned int)offsetof(typeof(field), data), |
26a50744 TZ |
444 | (unsigned int)BUF_PAGE_SIZE, |
445 | (unsigned int)is_signed_type(char)); | |
d1b182a8 SR |
446 | |
447 | return ret; | |
448 | } | |
449 | ||
15693458 SRRH |
450 | struct rb_irq_work { |
451 | struct irq_work work; | |
452 | wait_queue_head_t waiters; | |
453 | bool waiters_pending; | |
454 | }; | |
455 | ||
7a8e76a3 SR |
456 | /* |
457 | * head_page == tail_page && head == tail then buffer is empty. | |
458 | */ | |
459 | struct ring_buffer_per_cpu { | |
460 | int cpu; | |
985023de | 461 | atomic_t record_disabled; |
7a8e76a3 | 462 | struct ring_buffer *buffer; |
5389f6fa | 463 | raw_spinlock_t reader_lock; /* serialize readers */ |
445c8951 | 464 | arch_spinlock_t lock; |
7a8e76a3 | 465 | struct lock_class_key lock_key; |
438ced17 | 466 | unsigned int nr_pages; |
3adc54fa | 467 | struct list_head *pages; |
6f807acd SR |
468 | struct buffer_page *head_page; /* read from head */ |
469 | struct buffer_page *tail_page; /* write to tail */ | |
c3706f00 | 470 | struct buffer_page *commit_page; /* committed pages */ |
d769041f | 471 | struct buffer_page *reader_page; |
66a8cb95 SR |
472 | unsigned long lost_events; |
473 | unsigned long last_overrun; | |
c64e148a | 474 | local_t entries_bytes; |
e4906eff | 475 | local_t entries; |
884bfe89 SP |
476 | local_t overrun; |
477 | local_t commit_overrun; | |
478 | local_t dropped_events; | |
fa743953 SR |
479 | local_t committing; |
480 | local_t commits; | |
77ae365e | 481 | unsigned long read; |
c64e148a | 482 | unsigned long read_bytes; |
7a8e76a3 SR |
483 | u64 write_stamp; |
484 | u64 read_stamp; | |
438ced17 VN |
485 | /* ring buffer pages to update, > 0 to add, < 0 to remove */ |
486 | int nr_pages_to_update; | |
487 | struct list_head new_pages; /* new pages to add */ | |
83f40318 | 488 | struct work_struct update_pages_work; |
05fdd70d | 489 | struct completion update_done; |
15693458 SRRH |
490 | |
491 | struct rb_irq_work irq_work; | |
7a8e76a3 SR |
492 | }; |
493 | ||
494 | struct ring_buffer { | |
7a8e76a3 SR |
495 | unsigned flags; |
496 | int cpus; | |
7a8e76a3 | 497 | atomic_t record_disabled; |
83f40318 | 498 | atomic_t resize_disabled; |
00f62f61 | 499 | cpumask_var_t cpumask; |
7a8e76a3 | 500 | |
1f8a6a10 PZ |
501 | struct lock_class_key *reader_lock_key; |
502 | ||
7a8e76a3 SR |
503 | struct mutex mutex; |
504 | ||
505 | struct ring_buffer_per_cpu **buffers; | |
554f786e | 506 | |
59222efe | 507 | #ifdef CONFIG_HOTPLUG_CPU |
554f786e SR |
508 | struct notifier_block cpu_notify; |
509 | #endif | |
37886f6a | 510 | u64 (*clock)(void); |
15693458 SRRH |
511 | |
512 | struct rb_irq_work irq_work; | |
7a8e76a3 SR |
513 | }; |
514 | ||
515 | struct ring_buffer_iter { | |
516 | struct ring_buffer_per_cpu *cpu_buffer; | |
517 | unsigned long head; | |
518 | struct buffer_page *head_page; | |
492a74f4 SR |
519 | struct buffer_page *cache_reader_page; |
520 | unsigned long cache_read; | |
7a8e76a3 SR |
521 | u64 read_stamp; |
522 | }; | |
523 | ||
15693458 SRRH |
524 | /* |
525 | * rb_wake_up_waiters - wake up tasks waiting for ring buffer input | |
526 | * | |
527 | * Schedules a delayed work to wake up any task that is blocked on the | |
528 | * ring buffer waiters queue. | |
529 | */ | |
530 | static void rb_wake_up_waiters(struct irq_work *work) | |
531 | { | |
532 | struct rb_irq_work *rbwork = container_of(work, struct rb_irq_work, work); | |
533 | ||
534 | wake_up_all(&rbwork->waiters); | |
535 | } | |
536 | ||
537 | /** | |
538 | * ring_buffer_wait - wait for input to the ring buffer | |
539 | * @buffer: buffer to wait on | |
540 | * @cpu: the cpu buffer to wait on | |
541 | * | |
542 | * If @cpu == RING_BUFFER_ALL_CPUS then the task will wake up as soon | |
543 | * as data is added to any of the @buffer's cpu buffers. Otherwise | |
544 | * it will wait for data to be added to a specific cpu buffer. | |
545 | */ | |
546 | void ring_buffer_wait(struct ring_buffer *buffer, int cpu) | |
547 | { | |
548 | struct ring_buffer_per_cpu *cpu_buffer; | |
549 | DEFINE_WAIT(wait); | |
550 | struct rb_irq_work *work; | |
551 | ||
552 | /* | |
553 | * Depending on what the caller is waiting for, either any | |
554 | * data in any cpu buffer, or a specific buffer, put the | |
555 | * caller on the appropriate wait queue. | |
556 | */ | |
557 | if (cpu == RING_BUFFER_ALL_CPUS) | |
558 | work = &buffer->irq_work; | |
559 | else { | |
560 | cpu_buffer = buffer->buffers[cpu]; | |
561 | work = &cpu_buffer->irq_work; | |
562 | } | |
563 | ||
564 | ||
565 | prepare_to_wait(&work->waiters, &wait, TASK_INTERRUPTIBLE); | |
566 | ||
567 | /* | |
568 | * The events can happen in critical sections where | |
569 | * checking a work queue can cause deadlocks. | |
570 | * After adding a task to the queue, this flag is set | |
571 | * only to notify events to try to wake up the queue | |
572 | * using irq_work. | |
573 | * | |
574 | * We don't clear it even if the buffer is no longer | |
575 | * empty. The flag only causes the next event to run | |
576 | * irq_work to do the work queue wake up. The worse | |
577 | * that can happen if we race with !trace_empty() is that | |
578 | * an event will cause an irq_work to try to wake up | |
579 | * an empty queue. | |
580 | * | |
581 | * There's no reason to protect this flag either, as | |
582 | * the work queue and irq_work logic will do the necessary | |
583 | * synchronization for the wake ups. The only thing | |
584 | * that is necessary is that the wake up happens after | |
585 | * a task has been queued. It's OK for spurious wake ups. | |
586 | */ | |
587 | work->waiters_pending = true; | |
588 | ||
589 | if ((cpu == RING_BUFFER_ALL_CPUS && ring_buffer_empty(buffer)) || | |
590 | (cpu != RING_BUFFER_ALL_CPUS && ring_buffer_empty_cpu(buffer, cpu))) | |
591 | schedule(); | |
592 | ||
593 | finish_wait(&work->waiters, &wait); | |
594 | } | |
595 | ||
596 | /** | |
597 | * ring_buffer_poll_wait - poll on buffer input | |
598 | * @buffer: buffer to wait on | |
599 | * @cpu: the cpu buffer to wait on | |
600 | * @filp: the file descriptor | |
601 | * @poll_table: The poll descriptor | |
602 | * | |
603 | * If @cpu == RING_BUFFER_ALL_CPUS then the task will wake up as soon | |
604 | * as data is added to any of the @buffer's cpu buffers. Otherwise | |
605 | * it will wait for data to be added to a specific cpu buffer. | |
606 | * | |
607 | * Returns POLLIN | POLLRDNORM if data exists in the buffers, | |
608 | * zero otherwise. | |
609 | */ | |
610 | int ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu, | |
611 | struct file *filp, poll_table *poll_table) | |
612 | { | |
613 | struct ring_buffer_per_cpu *cpu_buffer; | |
614 | struct rb_irq_work *work; | |
615 | ||
616 | if ((cpu == RING_BUFFER_ALL_CPUS && !ring_buffer_empty(buffer)) || | |
617 | (cpu != RING_BUFFER_ALL_CPUS && !ring_buffer_empty_cpu(buffer, cpu))) | |
618 | return POLLIN | POLLRDNORM; | |
619 | ||
620 | if (cpu == RING_BUFFER_ALL_CPUS) | |
621 | work = &buffer->irq_work; | |
622 | else { | |
6721cb60 SRRH |
623 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
624 | return -EINVAL; | |
625 | ||
15693458 SRRH |
626 | cpu_buffer = buffer->buffers[cpu]; |
627 | work = &cpu_buffer->irq_work; | |
628 | } | |
629 | ||
630 | work->waiters_pending = true; | |
631 | poll_wait(filp, &work->waiters, poll_table); | |
632 | ||
633 | if ((cpu == RING_BUFFER_ALL_CPUS && !ring_buffer_empty(buffer)) || | |
634 | (cpu != RING_BUFFER_ALL_CPUS && !ring_buffer_empty_cpu(buffer, cpu))) | |
635 | return POLLIN | POLLRDNORM; | |
636 | return 0; | |
637 | } | |
638 | ||
f536aafc | 639 | /* buffer may be either ring_buffer or ring_buffer_per_cpu */ |
077c5407 SR |
640 | #define RB_WARN_ON(b, cond) \ |
641 | ({ \ | |
642 | int _____ret = unlikely(cond); \ | |
643 | if (_____ret) { \ | |
644 | if (__same_type(*(b), struct ring_buffer_per_cpu)) { \ | |
645 | struct ring_buffer_per_cpu *__b = \ | |
646 | (void *)b; \ | |
647 | atomic_inc(&__b->buffer->record_disabled); \ | |
648 | } else \ | |
649 | atomic_inc(&b->record_disabled); \ | |
650 | WARN_ON(1); \ | |
651 | } \ | |
652 | _____ret; \ | |
3e89c7bb | 653 | }) |
f536aafc | 654 | |
37886f6a SR |
655 | /* Up this if you want to test the TIME_EXTENTS and normalization */ |
656 | #define DEBUG_SHIFT 0 | |
657 | ||
6d3f1e12 | 658 | static inline u64 rb_time_stamp(struct ring_buffer *buffer) |
88eb0125 SR |
659 | { |
660 | /* shift to debug/test normalization and TIME_EXTENTS */ | |
661 | return buffer->clock() << DEBUG_SHIFT; | |
662 | } | |
663 | ||
37886f6a SR |
664 | u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu) |
665 | { | |
666 | u64 time; | |
667 | ||
668 | preempt_disable_notrace(); | |
6d3f1e12 | 669 | time = rb_time_stamp(buffer); |
37886f6a SR |
670 | preempt_enable_no_resched_notrace(); |
671 | ||
672 | return time; | |
673 | } | |
674 | EXPORT_SYMBOL_GPL(ring_buffer_time_stamp); | |
675 | ||
676 | void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer, | |
677 | int cpu, u64 *ts) | |
678 | { | |
679 | /* Just stupid testing the normalize function and deltas */ | |
680 | *ts >>= DEBUG_SHIFT; | |
681 | } | |
682 | EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp); | |
683 | ||
77ae365e SR |
684 | /* |
685 | * Making the ring buffer lockless makes things tricky. | |
686 | * Although writes only happen on the CPU that they are on, | |
687 | * and they only need to worry about interrupts. Reads can | |
688 | * happen on any CPU. | |
689 | * | |
690 | * The reader page is always off the ring buffer, but when the | |
691 | * reader finishes with a page, it needs to swap its page with | |
692 | * a new one from the buffer. The reader needs to take from | |
693 | * the head (writes go to the tail). But if a writer is in overwrite | |
694 | * mode and wraps, it must push the head page forward. | |
695 | * | |
696 | * Here lies the problem. | |
697 | * | |
698 | * The reader must be careful to replace only the head page, and | |
699 | * not another one. As described at the top of the file in the | |
700 | * ASCII art, the reader sets its old page to point to the next | |
701 | * page after head. It then sets the page after head to point to | |
702 | * the old reader page. But if the writer moves the head page | |
703 | * during this operation, the reader could end up with the tail. | |
704 | * | |
705 | * We use cmpxchg to help prevent this race. We also do something | |
706 | * special with the page before head. We set the LSB to 1. | |
707 | * | |
708 | * When the writer must push the page forward, it will clear the | |
709 | * bit that points to the head page, move the head, and then set | |
710 | * the bit that points to the new head page. | |
711 | * | |
712 | * We also don't want an interrupt coming in and moving the head | |
713 | * page on another writer. Thus we use the second LSB to catch | |
714 | * that too. Thus: | |
715 | * | |
716 | * head->list->prev->next bit 1 bit 0 | |
717 | * ------- ------- | |
718 | * Normal page 0 0 | |
719 | * Points to head page 0 1 | |
720 | * New head page 1 0 | |
721 | * | |
722 | * Note we can not trust the prev pointer of the head page, because: | |
723 | * | |
724 | * +----+ +-----+ +-----+ | |
725 | * | |------>| T |---X--->| N | | |
726 | * | |<------| | | | | |
727 | * +----+ +-----+ +-----+ | |
728 | * ^ ^ | | |
729 | * | +-----+ | | | |
730 | * +----------| R |----------+ | | |
731 | * | |<-----------+ | |
732 | * +-----+ | |
733 | * | |
734 | * Key: ---X--> HEAD flag set in pointer | |
735 | * T Tail page | |
736 | * R Reader page | |
737 | * N Next page | |
738 | * | |
739 | * (see __rb_reserve_next() to see where this happens) | |
740 | * | |
741 | * What the above shows is that the reader just swapped out | |
742 | * the reader page with a page in the buffer, but before it | |
743 | * could make the new header point back to the new page added | |
744 | * it was preempted by a writer. The writer moved forward onto | |
745 | * the new page added by the reader and is about to move forward | |
746 | * again. | |
747 | * | |
748 | * You can see, it is legitimate for the previous pointer of | |
749 | * the head (or any page) not to point back to itself. But only | |
750 | * temporarially. | |
751 | */ | |
752 | ||
753 | #define RB_PAGE_NORMAL 0UL | |
754 | #define RB_PAGE_HEAD 1UL | |
755 | #define RB_PAGE_UPDATE 2UL | |
756 | ||
757 | ||
758 | #define RB_FLAG_MASK 3UL | |
759 | ||
760 | /* PAGE_MOVED is not part of the mask */ | |
761 | #define RB_PAGE_MOVED 4UL | |
762 | ||
763 | /* | |
764 | * rb_list_head - remove any bit | |
765 | */ | |
766 | static struct list_head *rb_list_head(struct list_head *list) | |
767 | { | |
768 | unsigned long val = (unsigned long)list; | |
769 | ||
770 | return (struct list_head *)(val & ~RB_FLAG_MASK); | |
771 | } | |
772 | ||
773 | /* | |
6d3f1e12 | 774 | * rb_is_head_page - test if the given page is the head page |
77ae365e SR |
775 | * |
776 | * Because the reader may move the head_page pointer, we can | |
777 | * not trust what the head page is (it may be pointing to | |
778 | * the reader page). But if the next page is a header page, | |
779 | * its flags will be non zero. | |
780 | */ | |
42b16b3f | 781 | static inline int |
77ae365e SR |
782 | rb_is_head_page(struct ring_buffer_per_cpu *cpu_buffer, |
783 | struct buffer_page *page, struct list_head *list) | |
784 | { | |
785 | unsigned long val; | |
786 | ||
787 | val = (unsigned long)list->next; | |
788 | ||
789 | if ((val & ~RB_FLAG_MASK) != (unsigned long)&page->list) | |
790 | return RB_PAGE_MOVED; | |
791 | ||
792 | return val & RB_FLAG_MASK; | |
793 | } | |
794 | ||
795 | /* | |
796 | * rb_is_reader_page | |
797 | * | |
798 | * The unique thing about the reader page, is that, if the | |
799 | * writer is ever on it, the previous pointer never points | |
800 | * back to the reader page. | |
801 | */ | |
802 | static int rb_is_reader_page(struct buffer_page *page) | |
803 | { | |
804 | struct list_head *list = page->list.prev; | |
805 | ||
806 | return rb_list_head(list->next) != &page->list; | |
807 | } | |
808 | ||
809 | /* | |
810 | * rb_set_list_to_head - set a list_head to be pointing to head. | |
811 | */ | |
812 | static void rb_set_list_to_head(struct ring_buffer_per_cpu *cpu_buffer, | |
813 | struct list_head *list) | |
814 | { | |
815 | unsigned long *ptr; | |
816 | ||
817 | ptr = (unsigned long *)&list->next; | |
818 | *ptr |= RB_PAGE_HEAD; | |
819 | *ptr &= ~RB_PAGE_UPDATE; | |
820 | } | |
821 | ||
822 | /* | |
823 | * rb_head_page_activate - sets up head page | |
824 | */ | |
825 | static void rb_head_page_activate(struct ring_buffer_per_cpu *cpu_buffer) | |
826 | { | |
827 | struct buffer_page *head; | |
828 | ||
829 | head = cpu_buffer->head_page; | |
830 | if (!head) | |
831 | return; | |
832 | ||
833 | /* | |
834 | * Set the previous list pointer to have the HEAD flag. | |
835 | */ | |
836 | rb_set_list_to_head(cpu_buffer, head->list.prev); | |
837 | } | |
838 | ||
839 | static void rb_list_head_clear(struct list_head *list) | |
840 | { | |
841 | unsigned long *ptr = (unsigned long *)&list->next; | |
842 | ||
843 | *ptr &= ~RB_FLAG_MASK; | |
844 | } | |
845 | ||
846 | /* | |
847 | * rb_head_page_dactivate - clears head page ptr (for free list) | |
848 | */ | |
849 | static void | |
850 | rb_head_page_deactivate(struct ring_buffer_per_cpu *cpu_buffer) | |
851 | { | |
852 | struct list_head *hd; | |
853 | ||
854 | /* Go through the whole list and clear any pointers found. */ | |
855 | rb_list_head_clear(cpu_buffer->pages); | |
856 | ||
857 | list_for_each(hd, cpu_buffer->pages) | |
858 | rb_list_head_clear(hd); | |
859 | } | |
860 | ||
861 | static int rb_head_page_set(struct ring_buffer_per_cpu *cpu_buffer, | |
862 | struct buffer_page *head, | |
863 | struct buffer_page *prev, | |
864 | int old_flag, int new_flag) | |
865 | { | |
866 | struct list_head *list; | |
867 | unsigned long val = (unsigned long)&head->list; | |
868 | unsigned long ret; | |
869 | ||
870 | list = &prev->list; | |
871 | ||
872 | val &= ~RB_FLAG_MASK; | |
873 | ||
08a40816 SR |
874 | ret = cmpxchg((unsigned long *)&list->next, |
875 | val | old_flag, val | new_flag); | |
77ae365e SR |
876 | |
877 | /* check if the reader took the page */ | |
878 | if ((ret & ~RB_FLAG_MASK) != val) | |
879 | return RB_PAGE_MOVED; | |
880 | ||
881 | return ret & RB_FLAG_MASK; | |
882 | } | |
883 | ||
884 | static int rb_head_page_set_update(struct ring_buffer_per_cpu *cpu_buffer, | |
885 | struct buffer_page *head, | |
886 | struct buffer_page *prev, | |
887 | int old_flag) | |
888 | { | |
889 | return rb_head_page_set(cpu_buffer, head, prev, | |
890 | old_flag, RB_PAGE_UPDATE); | |
891 | } | |
892 | ||
893 | static int rb_head_page_set_head(struct ring_buffer_per_cpu *cpu_buffer, | |
894 | struct buffer_page *head, | |
895 | struct buffer_page *prev, | |
896 | int old_flag) | |
897 | { | |
898 | return rb_head_page_set(cpu_buffer, head, prev, | |
899 | old_flag, RB_PAGE_HEAD); | |
900 | } | |
901 | ||
902 | static int rb_head_page_set_normal(struct ring_buffer_per_cpu *cpu_buffer, | |
903 | struct buffer_page *head, | |
904 | struct buffer_page *prev, | |
905 | int old_flag) | |
906 | { | |
907 | return rb_head_page_set(cpu_buffer, head, prev, | |
908 | old_flag, RB_PAGE_NORMAL); | |
909 | } | |
910 | ||
911 | static inline void rb_inc_page(struct ring_buffer_per_cpu *cpu_buffer, | |
912 | struct buffer_page **bpage) | |
913 | { | |
914 | struct list_head *p = rb_list_head((*bpage)->list.next); | |
915 | ||
916 | *bpage = list_entry(p, struct buffer_page, list); | |
917 | } | |
918 | ||
919 | static struct buffer_page * | |
920 | rb_set_head_page(struct ring_buffer_per_cpu *cpu_buffer) | |
921 | { | |
922 | struct buffer_page *head; | |
923 | struct buffer_page *page; | |
924 | struct list_head *list; | |
925 | int i; | |
926 | ||
927 | if (RB_WARN_ON(cpu_buffer, !cpu_buffer->head_page)) | |
928 | return NULL; | |
929 | ||
930 | /* sanity check */ | |
931 | list = cpu_buffer->pages; | |
932 | if (RB_WARN_ON(cpu_buffer, rb_list_head(list->prev->next) != list)) | |
933 | return NULL; | |
934 | ||
935 | page = head = cpu_buffer->head_page; | |
936 | /* | |
937 | * It is possible that the writer moves the header behind | |
938 | * where we started, and we miss in one loop. | |
939 | * A second loop should grab the header, but we'll do | |
940 | * three loops just because I'm paranoid. | |
941 | */ | |
942 | for (i = 0; i < 3; i++) { | |
943 | do { | |
944 | if (rb_is_head_page(cpu_buffer, page, page->list.prev)) { | |
945 | cpu_buffer->head_page = page; | |
946 | return page; | |
947 | } | |
948 | rb_inc_page(cpu_buffer, &page); | |
949 | } while (page != head); | |
950 | } | |
951 | ||
952 | RB_WARN_ON(cpu_buffer, 1); | |
953 | ||
954 | return NULL; | |
955 | } | |
956 | ||
957 | static int rb_head_page_replace(struct buffer_page *old, | |
958 | struct buffer_page *new) | |
959 | { | |
960 | unsigned long *ptr = (unsigned long *)&old->list.prev->next; | |
961 | unsigned long val; | |
962 | unsigned long ret; | |
963 | ||
964 | val = *ptr & ~RB_FLAG_MASK; | |
965 | val |= RB_PAGE_HEAD; | |
966 | ||
08a40816 | 967 | ret = cmpxchg(ptr, val, (unsigned long)&new->list); |
77ae365e SR |
968 | |
969 | return ret == val; | |
970 | } | |
971 | ||
972 | /* | |
973 | * rb_tail_page_update - move the tail page forward | |
974 | * | |
975 | * Returns 1 if moved tail page, 0 if someone else did. | |
976 | */ | |
977 | static int rb_tail_page_update(struct ring_buffer_per_cpu *cpu_buffer, | |
978 | struct buffer_page *tail_page, | |
979 | struct buffer_page *next_page) | |
980 | { | |
981 | struct buffer_page *old_tail; | |
982 | unsigned long old_entries; | |
983 | unsigned long old_write; | |
984 | int ret = 0; | |
985 | ||
986 | /* | |
987 | * The tail page now needs to be moved forward. | |
988 | * | |
989 | * We need to reset the tail page, but without messing | |
990 | * with possible erasing of data brought in by interrupts | |
991 | * that have moved the tail page and are currently on it. | |
992 | * | |
993 | * We add a counter to the write field to denote this. | |
994 | */ | |
995 | old_write = local_add_return(RB_WRITE_INTCNT, &next_page->write); | |
996 | old_entries = local_add_return(RB_WRITE_INTCNT, &next_page->entries); | |
997 | ||
998 | /* | |
999 | * Just make sure we have seen our old_write and synchronize | |
1000 | * with any interrupts that come in. | |
1001 | */ | |
1002 | barrier(); | |
1003 | ||
1004 | /* | |
1005 | * If the tail page is still the same as what we think | |
1006 | * it is, then it is up to us to update the tail | |
1007 | * pointer. | |
1008 | */ | |
1009 | if (tail_page == cpu_buffer->tail_page) { | |
1010 | /* Zero the write counter */ | |
1011 | unsigned long val = old_write & ~RB_WRITE_MASK; | |
1012 | unsigned long eval = old_entries & ~RB_WRITE_MASK; | |
1013 | ||
1014 | /* | |
1015 | * This will only succeed if an interrupt did | |
1016 | * not come in and change it. In which case, we | |
1017 | * do not want to modify it. | |
da706d8b LJ |
1018 | * |
1019 | * We add (void) to let the compiler know that we do not care | |
1020 | * about the return value of these functions. We use the | |
1021 | * cmpxchg to only update if an interrupt did not already | |
1022 | * do it for us. If the cmpxchg fails, we don't care. | |
77ae365e | 1023 | */ |
da706d8b LJ |
1024 | (void)local_cmpxchg(&next_page->write, old_write, val); |
1025 | (void)local_cmpxchg(&next_page->entries, old_entries, eval); | |
77ae365e SR |
1026 | |
1027 | /* | |
1028 | * No need to worry about races with clearing out the commit. | |
1029 | * it only can increment when a commit takes place. But that | |
1030 | * only happens in the outer most nested commit. | |
1031 | */ | |
1032 | local_set(&next_page->page->commit, 0); | |
1033 | ||
1034 | old_tail = cmpxchg(&cpu_buffer->tail_page, | |
1035 | tail_page, next_page); | |
1036 | ||
1037 | if (old_tail == tail_page) | |
1038 | ret = 1; | |
1039 | } | |
1040 | ||
1041 | return ret; | |
1042 | } | |
1043 | ||
1044 | static int rb_check_bpage(struct ring_buffer_per_cpu *cpu_buffer, | |
1045 | struct buffer_page *bpage) | |
1046 | { | |
1047 | unsigned long val = (unsigned long)bpage; | |
1048 | ||
1049 | if (RB_WARN_ON(cpu_buffer, val & RB_FLAG_MASK)) | |
1050 | return 1; | |
1051 | ||
1052 | return 0; | |
1053 | } | |
1054 | ||
1055 | /** | |
1056 | * rb_check_list - make sure a pointer to a list has the last bits zero | |
1057 | */ | |
1058 | static int rb_check_list(struct ring_buffer_per_cpu *cpu_buffer, | |
1059 | struct list_head *list) | |
1060 | { | |
1061 | if (RB_WARN_ON(cpu_buffer, rb_list_head(list->prev) != list->prev)) | |
1062 | return 1; | |
1063 | if (RB_WARN_ON(cpu_buffer, rb_list_head(list->next) != list->next)) | |
1064 | return 1; | |
1065 | return 0; | |
1066 | } | |
1067 | ||
7a8e76a3 SR |
1068 | /** |
1069 | * check_pages - integrity check of buffer pages | |
1070 | * @cpu_buffer: CPU buffer with pages to test | |
1071 | * | |
c3706f00 | 1072 | * As a safety measure we check to make sure the data pages have not |
7a8e76a3 SR |
1073 | * been corrupted. |
1074 | */ | |
1075 | static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) | |
1076 | { | |
3adc54fa | 1077 | struct list_head *head = cpu_buffer->pages; |
044fa782 | 1078 | struct buffer_page *bpage, *tmp; |
7a8e76a3 | 1079 | |
308f7eeb SR |
1080 | /* Reset the head page if it exists */ |
1081 | if (cpu_buffer->head_page) | |
1082 | rb_set_head_page(cpu_buffer); | |
1083 | ||
77ae365e SR |
1084 | rb_head_page_deactivate(cpu_buffer); |
1085 | ||
3e89c7bb SR |
1086 | if (RB_WARN_ON(cpu_buffer, head->next->prev != head)) |
1087 | return -1; | |
1088 | if (RB_WARN_ON(cpu_buffer, head->prev->next != head)) | |
1089 | return -1; | |
7a8e76a3 | 1090 | |
77ae365e SR |
1091 | if (rb_check_list(cpu_buffer, head)) |
1092 | return -1; | |
1093 | ||
044fa782 | 1094 | list_for_each_entry_safe(bpage, tmp, head, list) { |
3e89c7bb | 1095 | if (RB_WARN_ON(cpu_buffer, |
044fa782 | 1096 | bpage->list.next->prev != &bpage->list)) |
3e89c7bb SR |
1097 | return -1; |
1098 | if (RB_WARN_ON(cpu_buffer, | |
044fa782 | 1099 | bpage->list.prev->next != &bpage->list)) |
3e89c7bb | 1100 | return -1; |
77ae365e SR |
1101 | if (rb_check_list(cpu_buffer, &bpage->list)) |
1102 | return -1; | |
7a8e76a3 SR |
1103 | } |
1104 | ||
77ae365e SR |
1105 | rb_head_page_activate(cpu_buffer); |
1106 | ||
7a8e76a3 SR |
1107 | return 0; |
1108 | } | |
1109 | ||
438ced17 | 1110 | static int __rb_allocate_pages(int nr_pages, struct list_head *pages, int cpu) |
7a8e76a3 | 1111 | { |
438ced17 | 1112 | int i; |
044fa782 | 1113 | struct buffer_page *bpage, *tmp; |
3adc54fa | 1114 | |
7a8e76a3 | 1115 | for (i = 0; i < nr_pages; i++) { |
7ea59064 | 1116 | struct page *page; |
d7ec4bfe VN |
1117 | /* |
1118 | * __GFP_NORETRY flag makes sure that the allocation fails | |
1119 | * gracefully without invoking oom-killer and the system is | |
1120 | * not destabilized. | |
1121 | */ | |
044fa782 | 1122 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
d7ec4bfe | 1123 | GFP_KERNEL | __GFP_NORETRY, |
438ced17 | 1124 | cpu_to_node(cpu)); |
044fa782 | 1125 | if (!bpage) |
e4c2ce82 | 1126 | goto free_pages; |
77ae365e | 1127 | |
438ced17 | 1128 | list_add(&bpage->list, pages); |
77ae365e | 1129 | |
438ced17 | 1130 | page = alloc_pages_node(cpu_to_node(cpu), |
d7ec4bfe | 1131 | GFP_KERNEL | __GFP_NORETRY, 0); |
7ea59064 | 1132 | if (!page) |
7a8e76a3 | 1133 | goto free_pages; |
7ea59064 | 1134 | bpage->page = page_address(page); |
044fa782 | 1135 | rb_init_page(bpage->page); |
7a8e76a3 SR |
1136 | } |
1137 | ||
438ced17 VN |
1138 | return 0; |
1139 | ||
1140 | free_pages: | |
1141 | list_for_each_entry_safe(bpage, tmp, pages, list) { | |
1142 | list_del_init(&bpage->list); | |
1143 | free_buffer_page(bpage); | |
1144 | } | |
1145 | ||
1146 | return -ENOMEM; | |
1147 | } | |
1148 | ||
1149 | static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, | |
1150 | unsigned nr_pages) | |
1151 | { | |
1152 | LIST_HEAD(pages); | |
1153 | ||
1154 | WARN_ON(!nr_pages); | |
1155 | ||
1156 | if (__rb_allocate_pages(nr_pages, &pages, cpu_buffer->cpu)) | |
1157 | return -ENOMEM; | |
1158 | ||
3adc54fa SR |
1159 | /* |
1160 | * The ring buffer page list is a circular list that does not | |
1161 | * start and end with a list head. All page list items point to | |
1162 | * other pages. | |
1163 | */ | |
1164 | cpu_buffer->pages = pages.next; | |
1165 | list_del(&pages); | |
7a8e76a3 | 1166 | |
438ced17 VN |
1167 | cpu_buffer->nr_pages = nr_pages; |
1168 | ||
7a8e76a3 SR |
1169 | rb_check_pages(cpu_buffer); |
1170 | ||
1171 | return 0; | |
7a8e76a3 SR |
1172 | } |
1173 | ||
1174 | static struct ring_buffer_per_cpu * | |
438ced17 | 1175 | rb_allocate_cpu_buffer(struct ring_buffer *buffer, int nr_pages, int cpu) |
7a8e76a3 SR |
1176 | { |
1177 | struct ring_buffer_per_cpu *cpu_buffer; | |
044fa782 | 1178 | struct buffer_page *bpage; |
7ea59064 | 1179 | struct page *page; |
7a8e76a3 SR |
1180 | int ret; |
1181 | ||
1182 | cpu_buffer = kzalloc_node(ALIGN(sizeof(*cpu_buffer), cache_line_size()), | |
1183 | GFP_KERNEL, cpu_to_node(cpu)); | |
1184 | if (!cpu_buffer) | |
1185 | return NULL; | |
1186 | ||
1187 | cpu_buffer->cpu = cpu; | |
1188 | cpu_buffer->buffer = buffer; | |
5389f6fa | 1189 | raw_spin_lock_init(&cpu_buffer->reader_lock); |
1f8a6a10 | 1190 | lockdep_set_class(&cpu_buffer->reader_lock, buffer->reader_lock_key); |
edc35bd7 | 1191 | cpu_buffer->lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; |
83f40318 | 1192 | INIT_WORK(&cpu_buffer->update_pages_work, update_pages_handler); |
05fdd70d | 1193 | init_completion(&cpu_buffer->update_done); |
15693458 | 1194 | init_irq_work(&cpu_buffer->irq_work.work, rb_wake_up_waiters); |
f1dc6725 | 1195 | init_waitqueue_head(&cpu_buffer->irq_work.waiters); |
7a8e76a3 | 1196 | |
044fa782 | 1197 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
e4c2ce82 | 1198 | GFP_KERNEL, cpu_to_node(cpu)); |
044fa782 | 1199 | if (!bpage) |
e4c2ce82 SR |
1200 | goto fail_free_buffer; |
1201 | ||
77ae365e SR |
1202 | rb_check_bpage(cpu_buffer, bpage); |
1203 | ||
044fa782 | 1204 | cpu_buffer->reader_page = bpage; |
7ea59064 VN |
1205 | page = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL, 0); |
1206 | if (!page) | |
e4c2ce82 | 1207 | goto fail_free_reader; |
7ea59064 | 1208 | bpage->page = page_address(page); |
044fa782 | 1209 | rb_init_page(bpage->page); |
e4c2ce82 | 1210 | |
d769041f | 1211 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); |
44b99462 | 1212 | INIT_LIST_HEAD(&cpu_buffer->new_pages); |
d769041f | 1213 | |
438ced17 | 1214 | ret = rb_allocate_pages(cpu_buffer, nr_pages); |
7a8e76a3 | 1215 | if (ret < 0) |
d769041f | 1216 | goto fail_free_reader; |
7a8e76a3 SR |
1217 | |
1218 | cpu_buffer->head_page | |
3adc54fa | 1219 | = list_entry(cpu_buffer->pages, struct buffer_page, list); |
bf41a158 | 1220 | cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; |
7a8e76a3 | 1221 | |
77ae365e SR |
1222 | rb_head_page_activate(cpu_buffer); |
1223 | ||
7a8e76a3 SR |
1224 | return cpu_buffer; |
1225 | ||
d769041f SR |
1226 | fail_free_reader: |
1227 | free_buffer_page(cpu_buffer->reader_page); | |
1228 | ||
7a8e76a3 SR |
1229 | fail_free_buffer: |
1230 | kfree(cpu_buffer); | |
1231 | return NULL; | |
1232 | } | |
1233 | ||
1234 | static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) | |
1235 | { | |
3adc54fa | 1236 | struct list_head *head = cpu_buffer->pages; |
044fa782 | 1237 | struct buffer_page *bpage, *tmp; |
7a8e76a3 | 1238 | |
d769041f SR |
1239 | free_buffer_page(cpu_buffer->reader_page); |
1240 | ||
77ae365e SR |
1241 | rb_head_page_deactivate(cpu_buffer); |
1242 | ||
3adc54fa SR |
1243 | if (head) { |
1244 | list_for_each_entry_safe(bpage, tmp, head, list) { | |
1245 | list_del_init(&bpage->list); | |
1246 | free_buffer_page(bpage); | |
1247 | } | |
1248 | bpage = list_entry(head, struct buffer_page, list); | |
044fa782 | 1249 | free_buffer_page(bpage); |
7a8e76a3 | 1250 | } |
3adc54fa | 1251 | |
7a8e76a3 SR |
1252 | kfree(cpu_buffer); |
1253 | } | |
1254 | ||
59222efe | 1255 | #ifdef CONFIG_HOTPLUG_CPU |
09c9e84d FW |
1256 | static int rb_cpu_notify(struct notifier_block *self, |
1257 | unsigned long action, void *hcpu); | |
554f786e SR |
1258 | #endif |
1259 | ||
7a8e76a3 SR |
1260 | /** |
1261 | * ring_buffer_alloc - allocate a new ring_buffer | |
68814b58 | 1262 | * @size: the size in bytes per cpu that is needed. |
7a8e76a3 SR |
1263 | * @flags: attributes to set for the ring buffer. |
1264 | * | |
1265 | * Currently the only flag that is available is the RB_FL_OVERWRITE | |
1266 | * flag. This flag means that the buffer will overwrite old data | |
1267 | * when the buffer wraps. If this flag is not set, the buffer will | |
1268 | * drop data when the tail hits the head. | |
1269 | */ | |
1f8a6a10 PZ |
1270 | struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, |
1271 | struct lock_class_key *key) | |
7a8e76a3 SR |
1272 | { |
1273 | struct ring_buffer *buffer; | |
1274 | int bsize; | |
438ced17 | 1275 | int cpu, nr_pages; |
7a8e76a3 SR |
1276 | |
1277 | /* keep it in its own cache line */ | |
1278 | buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()), | |
1279 | GFP_KERNEL); | |
1280 | if (!buffer) | |
1281 | return NULL; | |
1282 | ||
9e01c1b7 RR |
1283 | if (!alloc_cpumask_var(&buffer->cpumask, GFP_KERNEL)) |
1284 | goto fail_free_buffer; | |
1285 | ||
438ced17 | 1286 | nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
7a8e76a3 | 1287 | buffer->flags = flags; |
37886f6a | 1288 | buffer->clock = trace_clock_local; |
1f8a6a10 | 1289 | buffer->reader_lock_key = key; |
7a8e76a3 | 1290 | |
15693458 | 1291 | init_irq_work(&buffer->irq_work.work, rb_wake_up_waiters); |
f1dc6725 | 1292 | init_waitqueue_head(&buffer->irq_work.waiters); |
15693458 | 1293 | |
7a8e76a3 | 1294 | /* need at least two pages */ |
438ced17 VN |
1295 | if (nr_pages < 2) |
1296 | nr_pages = 2; | |
7a8e76a3 | 1297 | |
3bf832ce FW |
1298 | /* |
1299 | * In case of non-hotplug cpu, if the ring-buffer is allocated | |
1300 | * in early initcall, it will not be notified of secondary cpus. | |
1301 | * In that off case, we need to allocate for all possible cpus. | |
1302 | */ | |
1303 | #ifdef CONFIG_HOTPLUG_CPU | |
554f786e SR |
1304 | get_online_cpus(); |
1305 | cpumask_copy(buffer->cpumask, cpu_online_mask); | |
3bf832ce FW |
1306 | #else |
1307 | cpumask_copy(buffer->cpumask, cpu_possible_mask); | |
1308 | #endif | |
7a8e76a3 SR |
1309 | buffer->cpus = nr_cpu_ids; |
1310 | ||
1311 | bsize = sizeof(void *) * nr_cpu_ids; | |
1312 | buffer->buffers = kzalloc(ALIGN(bsize, cache_line_size()), | |
1313 | GFP_KERNEL); | |
1314 | if (!buffer->buffers) | |
9e01c1b7 | 1315 | goto fail_free_cpumask; |
7a8e76a3 SR |
1316 | |
1317 | for_each_buffer_cpu(buffer, cpu) { | |
1318 | buffer->buffers[cpu] = | |
438ced17 | 1319 | rb_allocate_cpu_buffer(buffer, nr_pages, cpu); |
7a8e76a3 SR |
1320 | if (!buffer->buffers[cpu]) |
1321 | goto fail_free_buffers; | |
1322 | } | |
1323 | ||
59222efe | 1324 | #ifdef CONFIG_HOTPLUG_CPU |
554f786e SR |
1325 | buffer->cpu_notify.notifier_call = rb_cpu_notify; |
1326 | buffer->cpu_notify.priority = 0; | |
1327 | register_cpu_notifier(&buffer->cpu_notify); | |
1328 | #endif | |
1329 | ||
1330 | put_online_cpus(); | |
7a8e76a3 SR |
1331 | mutex_init(&buffer->mutex); |
1332 | ||
1333 | return buffer; | |
1334 | ||
1335 | fail_free_buffers: | |
1336 | for_each_buffer_cpu(buffer, cpu) { | |
1337 | if (buffer->buffers[cpu]) | |
1338 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
1339 | } | |
1340 | kfree(buffer->buffers); | |
1341 | ||
9e01c1b7 RR |
1342 | fail_free_cpumask: |
1343 | free_cpumask_var(buffer->cpumask); | |
554f786e | 1344 | put_online_cpus(); |
9e01c1b7 | 1345 | |
7a8e76a3 SR |
1346 | fail_free_buffer: |
1347 | kfree(buffer); | |
1348 | return NULL; | |
1349 | } | |
1f8a6a10 | 1350 | EXPORT_SYMBOL_GPL(__ring_buffer_alloc); |
7a8e76a3 SR |
1351 | |
1352 | /** | |
1353 | * ring_buffer_free - free a ring buffer. | |
1354 | * @buffer: the buffer to free. | |
1355 | */ | |
1356 | void | |
1357 | ring_buffer_free(struct ring_buffer *buffer) | |
1358 | { | |
1359 | int cpu; | |
1360 | ||
554f786e SR |
1361 | get_online_cpus(); |
1362 | ||
59222efe | 1363 | #ifdef CONFIG_HOTPLUG_CPU |
554f786e SR |
1364 | unregister_cpu_notifier(&buffer->cpu_notify); |
1365 | #endif | |
1366 | ||
7a8e76a3 SR |
1367 | for_each_buffer_cpu(buffer, cpu) |
1368 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
1369 | ||
554f786e SR |
1370 | put_online_cpus(); |
1371 | ||
bd3f0221 | 1372 | kfree(buffer->buffers); |
9e01c1b7 RR |
1373 | free_cpumask_var(buffer->cpumask); |
1374 | ||
7a8e76a3 SR |
1375 | kfree(buffer); |
1376 | } | |
c4f50183 | 1377 | EXPORT_SYMBOL_GPL(ring_buffer_free); |
7a8e76a3 | 1378 | |
37886f6a SR |
1379 | void ring_buffer_set_clock(struct ring_buffer *buffer, |
1380 | u64 (*clock)(void)) | |
1381 | { | |
1382 | buffer->clock = clock; | |
1383 | } | |
1384 | ||
7a8e76a3 SR |
1385 | static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer); |
1386 | ||
83f40318 VN |
1387 | static inline unsigned long rb_page_entries(struct buffer_page *bpage) |
1388 | { | |
1389 | return local_read(&bpage->entries) & RB_WRITE_MASK; | |
1390 | } | |
1391 | ||
1392 | static inline unsigned long rb_page_write(struct buffer_page *bpage) | |
1393 | { | |
1394 | return local_read(&bpage->write) & RB_WRITE_MASK; | |
1395 | } | |
1396 | ||
5040b4b7 | 1397 | static int |
83f40318 | 1398 | rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned int nr_pages) |
7a8e76a3 | 1399 | { |
83f40318 VN |
1400 | struct list_head *tail_page, *to_remove, *next_page; |
1401 | struct buffer_page *to_remove_page, *tmp_iter_page; | |
1402 | struct buffer_page *last_page, *first_page; | |
1403 | unsigned int nr_removed; | |
1404 | unsigned long head_bit; | |
1405 | int page_entries; | |
1406 | ||
1407 | head_bit = 0; | |
7a8e76a3 | 1408 | |
5389f6fa | 1409 | raw_spin_lock_irq(&cpu_buffer->reader_lock); |
83f40318 VN |
1410 | atomic_inc(&cpu_buffer->record_disabled); |
1411 | /* | |
1412 | * We don't race with the readers since we have acquired the reader | |
1413 | * lock. We also don't race with writers after disabling recording. | |
1414 | * This makes it easy to figure out the first and the last page to be | |
1415 | * removed from the list. We unlink all the pages in between including | |
1416 | * the first and last pages. This is done in a busy loop so that we | |
1417 | * lose the least number of traces. | |
1418 | * The pages are freed after we restart recording and unlock readers. | |
1419 | */ | |
1420 | tail_page = &cpu_buffer->tail_page->list; | |
77ae365e | 1421 | |
83f40318 VN |
1422 | /* |
1423 | * tail page might be on reader page, we remove the next page | |
1424 | * from the ring buffer | |
1425 | */ | |
1426 | if (cpu_buffer->tail_page == cpu_buffer->reader_page) | |
1427 | tail_page = rb_list_head(tail_page->next); | |
1428 | to_remove = tail_page; | |
1429 | ||
1430 | /* start of pages to remove */ | |
1431 | first_page = list_entry(rb_list_head(to_remove->next), | |
1432 | struct buffer_page, list); | |
1433 | ||
1434 | for (nr_removed = 0; nr_removed < nr_pages; nr_removed++) { | |
1435 | to_remove = rb_list_head(to_remove)->next; | |
1436 | head_bit |= (unsigned long)to_remove & RB_PAGE_HEAD; | |
7a8e76a3 | 1437 | } |
7a8e76a3 | 1438 | |
83f40318 | 1439 | next_page = rb_list_head(to_remove)->next; |
7a8e76a3 | 1440 | |
83f40318 VN |
1441 | /* |
1442 | * Now we remove all pages between tail_page and next_page. | |
1443 | * Make sure that we have head_bit value preserved for the | |
1444 | * next page | |
1445 | */ | |
1446 | tail_page->next = (struct list_head *)((unsigned long)next_page | | |
1447 | head_bit); | |
1448 | next_page = rb_list_head(next_page); | |
1449 | next_page->prev = tail_page; | |
1450 | ||
1451 | /* make sure pages points to a valid page in the ring buffer */ | |
1452 | cpu_buffer->pages = next_page; | |
1453 | ||
1454 | /* update head page */ | |
1455 | if (head_bit) | |
1456 | cpu_buffer->head_page = list_entry(next_page, | |
1457 | struct buffer_page, list); | |
1458 | ||
1459 | /* | |
1460 | * change read pointer to make sure any read iterators reset | |
1461 | * themselves | |
1462 | */ | |
1463 | cpu_buffer->read = 0; | |
1464 | ||
1465 | /* pages are removed, resume tracing and then free the pages */ | |
1466 | atomic_dec(&cpu_buffer->record_disabled); | |
5389f6fa | 1467 | raw_spin_unlock_irq(&cpu_buffer->reader_lock); |
83f40318 VN |
1468 | |
1469 | RB_WARN_ON(cpu_buffer, list_empty(cpu_buffer->pages)); | |
1470 | ||
1471 | /* last buffer page to remove */ | |
1472 | last_page = list_entry(rb_list_head(to_remove), struct buffer_page, | |
1473 | list); | |
1474 | tmp_iter_page = first_page; | |
1475 | ||
1476 | do { | |
1477 | to_remove_page = tmp_iter_page; | |
1478 | rb_inc_page(cpu_buffer, &tmp_iter_page); | |
1479 | ||
1480 | /* update the counters */ | |
1481 | page_entries = rb_page_entries(to_remove_page); | |
1482 | if (page_entries) { | |
1483 | /* | |
1484 | * If something was added to this page, it was full | |
1485 | * since it is not the tail page. So we deduct the | |
1486 | * bytes consumed in ring buffer from here. | |
48fdc72f | 1487 | * Increment overrun to account for the lost events. |
83f40318 | 1488 | */ |
48fdc72f | 1489 | local_add(page_entries, &cpu_buffer->overrun); |
83f40318 VN |
1490 | local_sub(BUF_PAGE_SIZE, &cpu_buffer->entries_bytes); |
1491 | } | |
1492 | ||
1493 | /* | |
1494 | * We have already removed references to this list item, just | |
1495 | * free up the buffer_page and its page | |
1496 | */ | |
1497 | free_buffer_page(to_remove_page); | |
1498 | nr_removed--; | |
1499 | ||
1500 | } while (to_remove_page != last_page); | |
1501 | ||
1502 | RB_WARN_ON(cpu_buffer, nr_removed); | |
5040b4b7 VN |
1503 | |
1504 | return nr_removed == 0; | |
7a8e76a3 SR |
1505 | } |
1506 | ||
5040b4b7 VN |
1507 | static int |
1508 | rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer) | |
7a8e76a3 | 1509 | { |
5040b4b7 VN |
1510 | struct list_head *pages = &cpu_buffer->new_pages; |
1511 | int retries, success; | |
7a8e76a3 | 1512 | |
5389f6fa | 1513 | raw_spin_lock_irq(&cpu_buffer->reader_lock); |
5040b4b7 VN |
1514 | /* |
1515 | * We are holding the reader lock, so the reader page won't be swapped | |
1516 | * in the ring buffer. Now we are racing with the writer trying to | |
1517 | * move head page and the tail page. | |
1518 | * We are going to adapt the reader page update process where: | |
1519 | * 1. We first splice the start and end of list of new pages between | |
1520 | * the head page and its previous page. | |
1521 | * 2. We cmpxchg the prev_page->next to point from head page to the | |
1522 | * start of new pages list. | |
1523 | * 3. Finally, we update the head->prev to the end of new list. | |
1524 | * | |
1525 | * We will try this process 10 times, to make sure that we don't keep | |
1526 | * spinning. | |
1527 | */ | |
1528 | retries = 10; | |
1529 | success = 0; | |
1530 | while (retries--) { | |
1531 | struct list_head *head_page, *prev_page, *r; | |
1532 | struct list_head *last_page, *first_page; | |
1533 | struct list_head *head_page_with_bit; | |
77ae365e | 1534 | |
5040b4b7 | 1535 | head_page = &rb_set_head_page(cpu_buffer)->list; |
54f7be5b SR |
1536 | if (!head_page) |
1537 | break; | |
5040b4b7 VN |
1538 | prev_page = head_page->prev; |
1539 | ||
1540 | first_page = pages->next; | |
1541 | last_page = pages->prev; | |
1542 | ||
1543 | head_page_with_bit = (struct list_head *) | |
1544 | ((unsigned long)head_page | RB_PAGE_HEAD); | |
1545 | ||
1546 | last_page->next = head_page_with_bit; | |
1547 | first_page->prev = prev_page; | |
1548 | ||
1549 | r = cmpxchg(&prev_page->next, head_page_with_bit, first_page); | |
1550 | ||
1551 | if (r == head_page_with_bit) { | |
1552 | /* | |
1553 | * yay, we replaced the page pointer to our new list, | |
1554 | * now, we just have to update to head page's prev | |
1555 | * pointer to point to end of list | |
1556 | */ | |
1557 | head_page->prev = last_page; | |
1558 | success = 1; | |
1559 | break; | |
1560 | } | |
7a8e76a3 | 1561 | } |
7a8e76a3 | 1562 | |
5040b4b7 VN |
1563 | if (success) |
1564 | INIT_LIST_HEAD(pages); | |
1565 | /* | |
1566 | * If we weren't successful in adding in new pages, warn and stop | |
1567 | * tracing | |
1568 | */ | |
1569 | RB_WARN_ON(cpu_buffer, !success); | |
5389f6fa | 1570 | raw_spin_unlock_irq(&cpu_buffer->reader_lock); |
5040b4b7 VN |
1571 | |
1572 | /* free pages if they weren't inserted */ | |
1573 | if (!success) { | |
1574 | struct buffer_page *bpage, *tmp; | |
1575 | list_for_each_entry_safe(bpage, tmp, &cpu_buffer->new_pages, | |
1576 | list) { | |
1577 | list_del_init(&bpage->list); | |
1578 | free_buffer_page(bpage); | |
1579 | } | |
1580 | } | |
1581 | return success; | |
7a8e76a3 SR |
1582 | } |
1583 | ||
83f40318 | 1584 | static void rb_update_pages(struct ring_buffer_per_cpu *cpu_buffer) |
438ced17 | 1585 | { |
5040b4b7 VN |
1586 | int success; |
1587 | ||
438ced17 | 1588 | if (cpu_buffer->nr_pages_to_update > 0) |
5040b4b7 | 1589 | success = rb_insert_pages(cpu_buffer); |
438ced17 | 1590 | else |
5040b4b7 VN |
1591 | success = rb_remove_pages(cpu_buffer, |
1592 | -cpu_buffer->nr_pages_to_update); | |
83f40318 | 1593 | |
5040b4b7 VN |
1594 | if (success) |
1595 | cpu_buffer->nr_pages += cpu_buffer->nr_pages_to_update; | |
83f40318 VN |
1596 | } |
1597 | ||
1598 | static void update_pages_handler(struct work_struct *work) | |
1599 | { | |
1600 | struct ring_buffer_per_cpu *cpu_buffer = container_of(work, | |
1601 | struct ring_buffer_per_cpu, update_pages_work); | |
1602 | rb_update_pages(cpu_buffer); | |
05fdd70d | 1603 | complete(&cpu_buffer->update_done); |
438ced17 VN |
1604 | } |
1605 | ||
7a8e76a3 SR |
1606 | /** |
1607 | * ring_buffer_resize - resize the ring buffer | |
1608 | * @buffer: the buffer to resize. | |
1609 | * @size: the new size. | |
1610 | * | |
7a8e76a3 SR |
1611 | * Minimum size is 2 * BUF_PAGE_SIZE. |
1612 | * | |
83f40318 | 1613 | * Returns 0 on success and < 0 on failure. |
7a8e76a3 | 1614 | */ |
438ced17 VN |
1615 | int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, |
1616 | int cpu_id) | |
7a8e76a3 SR |
1617 | { |
1618 | struct ring_buffer_per_cpu *cpu_buffer; | |
438ced17 | 1619 | unsigned nr_pages; |
83f40318 | 1620 | int cpu, err = 0; |
7a8e76a3 | 1621 | |
ee51a1de IM |
1622 | /* |
1623 | * Always succeed at resizing a non-existent buffer: | |
1624 | */ | |
1625 | if (!buffer) | |
1626 | return size; | |
1627 | ||
6a31e1f1 SR |
1628 | /* Make sure the requested buffer exists */ |
1629 | if (cpu_id != RING_BUFFER_ALL_CPUS && | |
1630 | !cpumask_test_cpu(cpu_id, buffer->cpumask)) | |
1631 | return size; | |
1632 | ||
7a8e76a3 SR |
1633 | size = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
1634 | size *= BUF_PAGE_SIZE; | |
7a8e76a3 SR |
1635 | |
1636 | /* we need a minimum of two pages */ | |
1637 | if (size < BUF_PAGE_SIZE * 2) | |
1638 | size = BUF_PAGE_SIZE * 2; | |
1639 | ||
83f40318 | 1640 | nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
18421015 | 1641 | |
83f40318 VN |
1642 | /* |
1643 | * Don't succeed if resizing is disabled, as a reader might be | |
1644 | * manipulating the ring buffer and is expecting a sane state while | |
1645 | * this is true. | |
1646 | */ | |
1647 | if (atomic_read(&buffer->resize_disabled)) | |
1648 | return -EBUSY; | |
18421015 | 1649 | |
83f40318 | 1650 | /* prevent another thread from changing buffer sizes */ |
7a8e76a3 | 1651 | mutex_lock(&buffer->mutex); |
7a8e76a3 | 1652 | |
438ced17 VN |
1653 | if (cpu_id == RING_BUFFER_ALL_CPUS) { |
1654 | /* calculate the pages to update */ | |
7a8e76a3 SR |
1655 | for_each_buffer_cpu(buffer, cpu) { |
1656 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 | 1657 | |
438ced17 VN |
1658 | cpu_buffer->nr_pages_to_update = nr_pages - |
1659 | cpu_buffer->nr_pages; | |
438ced17 VN |
1660 | /* |
1661 | * nothing more to do for removing pages or no update | |
1662 | */ | |
1663 | if (cpu_buffer->nr_pages_to_update <= 0) | |
1664 | continue; | |
d7ec4bfe | 1665 | /* |
438ced17 VN |
1666 | * to add pages, make sure all new pages can be |
1667 | * allocated without receiving ENOMEM | |
d7ec4bfe | 1668 | */ |
438ced17 VN |
1669 | INIT_LIST_HEAD(&cpu_buffer->new_pages); |
1670 | if (__rb_allocate_pages(cpu_buffer->nr_pages_to_update, | |
83f40318 | 1671 | &cpu_buffer->new_pages, cpu)) { |
438ced17 | 1672 | /* not enough memory for new pages */ |
83f40318 VN |
1673 | err = -ENOMEM; |
1674 | goto out_err; | |
1675 | } | |
1676 | } | |
1677 | ||
1678 | get_online_cpus(); | |
1679 | /* | |
1680 | * Fire off all the required work handlers | |
05fdd70d | 1681 | * We can't schedule on offline CPUs, but it's not necessary |
83f40318 VN |
1682 | * since we can change their buffer sizes without any race. |
1683 | */ | |
1684 | for_each_buffer_cpu(buffer, cpu) { | |
1685 | cpu_buffer = buffer->buffers[cpu]; | |
05fdd70d | 1686 | if (!cpu_buffer->nr_pages_to_update) |
83f40318 VN |
1687 | continue; |
1688 | ||
f5eb5588 SRRH |
1689 | /* The update must run on the CPU that is being updated. */ |
1690 | preempt_disable(); | |
1691 | if (cpu == smp_processor_id() || !cpu_online(cpu)) { | |
1692 | rb_update_pages(cpu_buffer); | |
1693 | cpu_buffer->nr_pages_to_update = 0; | |
1694 | } else { | |
1695 | /* | |
1696 | * Can not disable preemption for schedule_work_on() | |
1697 | * on PREEMPT_RT. | |
1698 | */ | |
1699 | preempt_enable(); | |
05fdd70d VN |
1700 | schedule_work_on(cpu, |
1701 | &cpu_buffer->update_pages_work); | |
f5eb5588 SRRH |
1702 | preempt_disable(); |
1703 | } | |
1704 | preempt_enable(); | |
7a8e76a3 | 1705 | } |
7a8e76a3 | 1706 | |
438ced17 VN |
1707 | /* wait for all the updates to complete */ |
1708 | for_each_buffer_cpu(buffer, cpu) { | |
1709 | cpu_buffer = buffer->buffers[cpu]; | |
05fdd70d | 1710 | if (!cpu_buffer->nr_pages_to_update) |
83f40318 VN |
1711 | continue; |
1712 | ||
05fdd70d VN |
1713 | if (cpu_online(cpu)) |
1714 | wait_for_completion(&cpu_buffer->update_done); | |
83f40318 | 1715 | cpu_buffer->nr_pages_to_update = 0; |
438ced17 | 1716 | } |
83f40318 VN |
1717 | |
1718 | put_online_cpus(); | |
438ced17 | 1719 | } else { |
8e49f418 VN |
1720 | /* Make sure this CPU has been intitialized */ |
1721 | if (!cpumask_test_cpu(cpu_id, buffer->cpumask)) | |
1722 | goto out; | |
1723 | ||
438ced17 | 1724 | cpu_buffer = buffer->buffers[cpu_id]; |
83f40318 | 1725 | |
438ced17 VN |
1726 | if (nr_pages == cpu_buffer->nr_pages) |
1727 | goto out; | |
7a8e76a3 | 1728 | |
438ced17 VN |
1729 | cpu_buffer->nr_pages_to_update = nr_pages - |
1730 | cpu_buffer->nr_pages; | |
1731 | ||
1732 | INIT_LIST_HEAD(&cpu_buffer->new_pages); | |
1733 | if (cpu_buffer->nr_pages_to_update > 0 && | |
1734 | __rb_allocate_pages(cpu_buffer->nr_pages_to_update, | |
83f40318 VN |
1735 | &cpu_buffer->new_pages, cpu_id)) { |
1736 | err = -ENOMEM; | |
1737 | goto out_err; | |
1738 | } | |
438ced17 | 1739 | |
83f40318 VN |
1740 | get_online_cpus(); |
1741 | ||
f5eb5588 SRRH |
1742 | preempt_disable(); |
1743 | /* The update must run on the CPU that is being updated. */ | |
1744 | if (cpu_id == smp_processor_id() || !cpu_online(cpu_id)) | |
1745 | rb_update_pages(cpu_buffer); | |
1746 | else { | |
1747 | /* | |
1748 | * Can not disable preemption for schedule_work_on() | |
1749 | * on PREEMPT_RT. | |
1750 | */ | |
1751 | preempt_enable(); | |
83f40318 VN |
1752 | schedule_work_on(cpu_id, |
1753 | &cpu_buffer->update_pages_work); | |
05fdd70d | 1754 | wait_for_completion(&cpu_buffer->update_done); |
f5eb5588 SRRH |
1755 | preempt_disable(); |
1756 | } | |
1757 | preempt_enable(); | |
83f40318 | 1758 | |
83f40318 | 1759 | cpu_buffer->nr_pages_to_update = 0; |
05fdd70d | 1760 | put_online_cpus(); |
438ced17 | 1761 | } |
7a8e76a3 SR |
1762 | |
1763 | out: | |
659f451f SR |
1764 | /* |
1765 | * The ring buffer resize can happen with the ring buffer | |
1766 | * enabled, so that the update disturbs the tracing as little | |
1767 | * as possible. But if the buffer is disabled, we do not need | |
1768 | * to worry about that, and we can take the time to verify | |
1769 | * that the buffer is not corrupt. | |
1770 | */ | |
1771 | if (atomic_read(&buffer->record_disabled)) { | |
1772 | atomic_inc(&buffer->record_disabled); | |
1773 | /* | |
1774 | * Even though the buffer was disabled, we must make sure | |
1775 | * that it is truly disabled before calling rb_check_pages. | |
1776 | * There could have been a race between checking | |
1777 | * record_disable and incrementing it. | |
1778 | */ | |
1779 | synchronize_sched(); | |
1780 | for_each_buffer_cpu(buffer, cpu) { | |
1781 | cpu_buffer = buffer->buffers[cpu]; | |
1782 | rb_check_pages(cpu_buffer); | |
1783 | } | |
1784 | atomic_dec(&buffer->record_disabled); | |
1785 | } | |
1786 | ||
7a8e76a3 | 1787 | mutex_unlock(&buffer->mutex); |
7a8e76a3 SR |
1788 | return size; |
1789 | ||
83f40318 | 1790 | out_err: |
438ced17 VN |
1791 | for_each_buffer_cpu(buffer, cpu) { |
1792 | struct buffer_page *bpage, *tmp; | |
83f40318 | 1793 | |
438ced17 | 1794 | cpu_buffer = buffer->buffers[cpu]; |
438ced17 | 1795 | cpu_buffer->nr_pages_to_update = 0; |
83f40318 | 1796 | |
438ced17 VN |
1797 | if (list_empty(&cpu_buffer->new_pages)) |
1798 | continue; | |
83f40318 | 1799 | |
438ced17 VN |
1800 | list_for_each_entry_safe(bpage, tmp, &cpu_buffer->new_pages, |
1801 | list) { | |
1802 | list_del_init(&bpage->list); | |
1803 | free_buffer_page(bpage); | |
1804 | } | |
7a8e76a3 | 1805 | } |
641d2f63 | 1806 | mutex_unlock(&buffer->mutex); |
83f40318 | 1807 | return err; |
7a8e76a3 | 1808 | } |
c4f50183 | 1809 | EXPORT_SYMBOL_GPL(ring_buffer_resize); |
7a8e76a3 | 1810 | |
750912fa DS |
1811 | void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val) |
1812 | { | |
1813 | mutex_lock(&buffer->mutex); | |
1814 | if (val) | |
1815 | buffer->flags |= RB_FL_OVERWRITE; | |
1816 | else | |
1817 | buffer->flags &= ~RB_FL_OVERWRITE; | |
1818 | mutex_unlock(&buffer->mutex); | |
1819 | } | |
1820 | EXPORT_SYMBOL_GPL(ring_buffer_change_overwrite); | |
1821 | ||
8789a9e7 | 1822 | static inline void * |
044fa782 | 1823 | __rb_data_page_index(struct buffer_data_page *bpage, unsigned index) |
8789a9e7 | 1824 | { |
044fa782 | 1825 | return bpage->data + index; |
8789a9e7 SR |
1826 | } |
1827 | ||
044fa782 | 1828 | static inline void *__rb_page_index(struct buffer_page *bpage, unsigned index) |
7a8e76a3 | 1829 | { |
044fa782 | 1830 | return bpage->page->data + index; |
7a8e76a3 SR |
1831 | } |
1832 | ||
1833 | static inline struct ring_buffer_event * | |
d769041f | 1834 | rb_reader_event(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 1835 | { |
6f807acd SR |
1836 | return __rb_page_index(cpu_buffer->reader_page, |
1837 | cpu_buffer->reader_page->read); | |
1838 | } | |
1839 | ||
7a8e76a3 SR |
1840 | static inline struct ring_buffer_event * |
1841 | rb_iter_head_event(struct ring_buffer_iter *iter) | |
1842 | { | |
6f807acd | 1843 | return __rb_page_index(iter->head_page, iter->head); |
7a8e76a3 SR |
1844 | } |
1845 | ||
bf41a158 SR |
1846 | static inline unsigned rb_page_commit(struct buffer_page *bpage) |
1847 | { | |
abc9b56d | 1848 | return local_read(&bpage->page->commit); |
bf41a158 SR |
1849 | } |
1850 | ||
25985edc | 1851 | /* Size is determined by what has been committed */ |
bf41a158 SR |
1852 | static inline unsigned rb_page_size(struct buffer_page *bpage) |
1853 | { | |
1854 | return rb_page_commit(bpage); | |
1855 | } | |
1856 | ||
1857 | static inline unsigned | |
1858 | rb_commit_index(struct ring_buffer_per_cpu *cpu_buffer) | |
1859 | { | |
1860 | return rb_page_commit(cpu_buffer->commit_page); | |
1861 | } | |
1862 | ||
bf41a158 SR |
1863 | static inline unsigned |
1864 | rb_event_index(struct ring_buffer_event *event) | |
1865 | { | |
1866 | unsigned long addr = (unsigned long)event; | |
1867 | ||
22f470f8 | 1868 | return (addr & ~PAGE_MASK) - BUF_PAGE_HDR_SIZE; |
bf41a158 SR |
1869 | } |
1870 | ||
0f0c85fc | 1871 | static inline int |
fa743953 SR |
1872 | rb_event_is_commit(struct ring_buffer_per_cpu *cpu_buffer, |
1873 | struct ring_buffer_event *event) | |
bf41a158 SR |
1874 | { |
1875 | unsigned long addr = (unsigned long)event; | |
1876 | unsigned long index; | |
1877 | ||
1878 | index = rb_event_index(event); | |
1879 | addr &= PAGE_MASK; | |
1880 | ||
1881 | return cpu_buffer->commit_page->page == (void *)addr && | |
1882 | rb_commit_index(cpu_buffer) == index; | |
1883 | } | |
1884 | ||
34a148bf | 1885 | static void |
bf41a158 | 1886 | rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 1887 | { |
77ae365e SR |
1888 | unsigned long max_count; |
1889 | ||
bf41a158 SR |
1890 | /* |
1891 | * We only race with interrupts and NMIs on this CPU. | |
1892 | * If we own the commit event, then we can commit | |
1893 | * all others that interrupted us, since the interruptions | |
1894 | * are in stack format (they finish before they come | |
1895 | * back to us). This allows us to do a simple loop to | |
1896 | * assign the commit to the tail. | |
1897 | */ | |
a8ccf1d6 | 1898 | again: |
438ced17 | 1899 | max_count = cpu_buffer->nr_pages * 100; |
77ae365e | 1900 | |
bf41a158 | 1901 | while (cpu_buffer->commit_page != cpu_buffer->tail_page) { |
77ae365e SR |
1902 | if (RB_WARN_ON(cpu_buffer, !(--max_count))) |
1903 | return; | |
1904 | if (RB_WARN_ON(cpu_buffer, | |
1905 | rb_is_reader_page(cpu_buffer->tail_page))) | |
1906 | return; | |
1907 | local_set(&cpu_buffer->commit_page->page->commit, | |
1908 | rb_page_write(cpu_buffer->commit_page)); | |
bf41a158 | 1909 | rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); |
abc9b56d SR |
1910 | cpu_buffer->write_stamp = |
1911 | cpu_buffer->commit_page->page->time_stamp; | |
bf41a158 SR |
1912 | /* add barrier to keep gcc from optimizing too much */ |
1913 | barrier(); | |
1914 | } | |
1915 | while (rb_commit_index(cpu_buffer) != | |
1916 | rb_page_write(cpu_buffer->commit_page)) { | |
77ae365e SR |
1917 | |
1918 | local_set(&cpu_buffer->commit_page->page->commit, | |
1919 | rb_page_write(cpu_buffer->commit_page)); | |
1920 | RB_WARN_ON(cpu_buffer, | |
1921 | local_read(&cpu_buffer->commit_page->page->commit) & | |
1922 | ~RB_WRITE_MASK); | |
bf41a158 SR |
1923 | barrier(); |
1924 | } | |
a8ccf1d6 SR |
1925 | |
1926 | /* again, keep gcc from optimizing */ | |
1927 | barrier(); | |
1928 | ||
1929 | /* | |
1930 | * If an interrupt came in just after the first while loop | |
1931 | * and pushed the tail page forward, we will be left with | |
1932 | * a dangling commit that will never go forward. | |
1933 | */ | |
1934 | if (unlikely(cpu_buffer->commit_page != cpu_buffer->tail_page)) | |
1935 | goto again; | |
7a8e76a3 SR |
1936 | } |
1937 | ||
d769041f | 1938 | static void rb_reset_reader_page(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 1939 | { |
abc9b56d | 1940 | cpu_buffer->read_stamp = cpu_buffer->reader_page->page->time_stamp; |
6f807acd | 1941 | cpu_buffer->reader_page->read = 0; |
d769041f SR |
1942 | } |
1943 | ||
34a148bf | 1944 | static void rb_inc_iter(struct ring_buffer_iter *iter) |
d769041f SR |
1945 | { |
1946 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
1947 | ||
1948 | /* | |
1949 | * The iterator could be on the reader page (it starts there). | |
1950 | * But the head could have moved, since the reader was | |
1951 | * found. Check for this case and assign the iterator | |
1952 | * to the head page instead of next. | |
1953 | */ | |
1954 | if (iter->head_page == cpu_buffer->reader_page) | |
77ae365e | 1955 | iter->head_page = rb_set_head_page(cpu_buffer); |
d769041f SR |
1956 | else |
1957 | rb_inc_page(cpu_buffer, &iter->head_page); | |
1958 | ||
abc9b56d | 1959 | iter->read_stamp = iter->head_page->page->time_stamp; |
7a8e76a3 SR |
1960 | iter->head = 0; |
1961 | } | |
1962 | ||
69d1b839 SR |
1963 | /* Slow path, do not inline */ |
1964 | static noinline struct ring_buffer_event * | |
1965 | rb_add_time_stamp(struct ring_buffer_event *event, u64 delta) | |
1966 | { | |
1967 | event->type_len = RINGBUF_TYPE_TIME_EXTEND; | |
1968 | ||
1969 | /* Not the first event on the page? */ | |
1970 | if (rb_event_index(event)) { | |
1971 | event->time_delta = delta & TS_MASK; | |
1972 | event->array[0] = delta >> TS_SHIFT; | |
1973 | } else { | |
1974 | /* nope, just zero it */ | |
1975 | event->time_delta = 0; | |
1976 | event->array[0] = 0; | |
1977 | } | |
1978 | ||
1979 | return skip_time_extend(event); | |
1980 | } | |
1981 | ||
7a8e76a3 | 1982 | /** |
01e3e710 | 1983 | * rb_update_event - update event type and data |
7a8e76a3 SR |
1984 | * @event: the even to update |
1985 | * @type: the type of event | |
1986 | * @length: the size of the event field in the ring buffer | |
1987 | * | |
1988 | * Update the type and data fields of the event. The length | |
1989 | * is the actual size that is written to the ring buffer, | |
1990 | * and with this, we can determine what to place into the | |
1991 | * data field. | |
1992 | */ | |
34a148bf | 1993 | static void |
69d1b839 SR |
1994 | rb_update_event(struct ring_buffer_per_cpu *cpu_buffer, |
1995 | struct ring_buffer_event *event, unsigned length, | |
1996 | int add_timestamp, u64 delta) | |
7a8e76a3 | 1997 | { |
69d1b839 SR |
1998 | /* Only a commit updates the timestamp */ |
1999 | if (unlikely(!rb_event_is_commit(cpu_buffer, event))) | |
2000 | delta = 0; | |
7a8e76a3 | 2001 | |
69d1b839 SR |
2002 | /* |
2003 | * If we need to add a timestamp, then we | |
2004 | * add it to the start of the resevered space. | |
2005 | */ | |
2006 | if (unlikely(add_timestamp)) { | |
2007 | event = rb_add_time_stamp(event, delta); | |
2008 | length -= RB_LEN_TIME_EXTEND; | |
2009 | delta = 0; | |
7a8e76a3 | 2010 | } |
69d1b839 SR |
2011 | |
2012 | event->time_delta = delta; | |
2013 | length -= RB_EVNT_HDR_SIZE; | |
2014 | if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) { | |
2015 | event->type_len = 0; | |
2016 | event->array[0] = length; | |
2017 | } else | |
2018 | event->type_len = DIV_ROUND_UP(length, RB_ALIGNMENT); | |
7a8e76a3 SR |
2019 | } |
2020 | ||
77ae365e SR |
2021 | /* |
2022 | * rb_handle_head_page - writer hit the head page | |
2023 | * | |
2024 | * Returns: +1 to retry page | |
2025 | * 0 to continue | |
2026 | * -1 on error | |
2027 | */ | |
2028 | static int | |
2029 | rb_handle_head_page(struct ring_buffer_per_cpu *cpu_buffer, | |
2030 | struct buffer_page *tail_page, | |
2031 | struct buffer_page *next_page) | |
2032 | { | |
2033 | struct buffer_page *new_head; | |
2034 | int entries; | |
2035 | int type; | |
2036 | int ret; | |
2037 | ||
2038 | entries = rb_page_entries(next_page); | |
2039 | ||
2040 | /* | |
2041 | * The hard part is here. We need to move the head | |
2042 | * forward, and protect against both readers on | |
2043 | * other CPUs and writers coming in via interrupts. | |
2044 | */ | |
2045 | type = rb_head_page_set_update(cpu_buffer, next_page, tail_page, | |
2046 | RB_PAGE_HEAD); | |
2047 | ||
2048 | /* | |
2049 | * type can be one of four: | |
2050 | * NORMAL - an interrupt already moved it for us | |
2051 | * HEAD - we are the first to get here. | |
2052 | * UPDATE - we are the interrupt interrupting | |
2053 | * a current move. | |
2054 | * MOVED - a reader on another CPU moved the next | |
2055 | * pointer to its reader page. Give up | |
2056 | * and try again. | |
2057 | */ | |
2058 | ||
2059 | switch (type) { | |
2060 | case RB_PAGE_HEAD: | |
2061 | /* | |
2062 | * We changed the head to UPDATE, thus | |
2063 | * it is our responsibility to update | |
2064 | * the counters. | |
2065 | */ | |
2066 | local_add(entries, &cpu_buffer->overrun); | |
c64e148a | 2067 | local_sub(BUF_PAGE_SIZE, &cpu_buffer->entries_bytes); |
77ae365e SR |
2068 | |
2069 | /* | |
2070 | * The entries will be zeroed out when we move the | |
2071 | * tail page. | |
2072 | */ | |
2073 | ||
2074 | /* still more to do */ | |
2075 | break; | |
2076 | ||
2077 | case RB_PAGE_UPDATE: | |
2078 | /* | |
2079 | * This is an interrupt that interrupt the | |
2080 | * previous update. Still more to do. | |
2081 | */ | |
2082 | break; | |
2083 | case RB_PAGE_NORMAL: | |
2084 | /* | |
2085 | * An interrupt came in before the update | |
2086 | * and processed this for us. | |
2087 | * Nothing left to do. | |
2088 | */ | |
2089 | return 1; | |
2090 | case RB_PAGE_MOVED: | |
2091 | /* | |
2092 | * The reader is on another CPU and just did | |
2093 | * a swap with our next_page. | |
2094 | * Try again. | |
2095 | */ | |
2096 | return 1; | |
2097 | default: | |
2098 | RB_WARN_ON(cpu_buffer, 1); /* WTF??? */ | |
2099 | return -1; | |
2100 | } | |
2101 | ||
2102 | /* | |
2103 | * Now that we are here, the old head pointer is | |
2104 | * set to UPDATE. This will keep the reader from | |
2105 | * swapping the head page with the reader page. | |
2106 | * The reader (on another CPU) will spin till | |
2107 | * we are finished. | |
2108 | * | |
2109 | * We just need to protect against interrupts | |
2110 | * doing the job. We will set the next pointer | |
2111 | * to HEAD. After that, we set the old pointer | |
2112 | * to NORMAL, but only if it was HEAD before. | |
2113 | * otherwise we are an interrupt, and only | |
2114 | * want the outer most commit to reset it. | |
2115 | */ | |
2116 | new_head = next_page; | |
2117 | rb_inc_page(cpu_buffer, &new_head); | |
2118 | ||
2119 | ret = rb_head_page_set_head(cpu_buffer, new_head, next_page, | |
2120 | RB_PAGE_NORMAL); | |
2121 | ||
2122 | /* | |
2123 | * Valid returns are: | |
2124 | * HEAD - an interrupt came in and already set it. | |
2125 | * NORMAL - One of two things: | |
2126 | * 1) We really set it. | |
2127 | * 2) A bunch of interrupts came in and moved | |
2128 | * the page forward again. | |
2129 | */ | |
2130 | switch (ret) { | |
2131 | case RB_PAGE_HEAD: | |
2132 | case RB_PAGE_NORMAL: | |
2133 | /* OK */ | |
2134 | break; | |
2135 | default: | |
2136 | RB_WARN_ON(cpu_buffer, 1); | |
2137 | return -1; | |
2138 | } | |
2139 | ||
2140 | /* | |
2141 | * It is possible that an interrupt came in, | |
2142 | * set the head up, then more interrupts came in | |
2143 | * and moved it again. When we get back here, | |
2144 | * the page would have been set to NORMAL but we | |
2145 | * just set it back to HEAD. | |
2146 | * | |
2147 | * How do you detect this? Well, if that happened | |
2148 | * the tail page would have moved. | |
2149 | */ | |
2150 | if (ret == RB_PAGE_NORMAL) { | |
2151 | /* | |
2152 | * If the tail had moved passed next, then we need | |
2153 | * to reset the pointer. | |
2154 | */ | |
2155 | if (cpu_buffer->tail_page != tail_page && | |
2156 | cpu_buffer->tail_page != next_page) | |
2157 | rb_head_page_set_normal(cpu_buffer, new_head, | |
2158 | next_page, | |
2159 | RB_PAGE_HEAD); | |
2160 | } | |
2161 | ||
2162 | /* | |
2163 | * If this was the outer most commit (the one that | |
2164 | * changed the original pointer from HEAD to UPDATE), | |
2165 | * then it is up to us to reset it to NORMAL. | |
2166 | */ | |
2167 | if (type == RB_PAGE_HEAD) { | |
2168 | ret = rb_head_page_set_normal(cpu_buffer, next_page, | |
2169 | tail_page, | |
2170 | RB_PAGE_UPDATE); | |
2171 | if (RB_WARN_ON(cpu_buffer, | |
2172 | ret != RB_PAGE_UPDATE)) | |
2173 | return -1; | |
2174 | } | |
2175 | ||
2176 | return 0; | |
2177 | } | |
2178 | ||
34a148bf | 2179 | static unsigned rb_calculate_event_length(unsigned length) |
7a8e76a3 SR |
2180 | { |
2181 | struct ring_buffer_event event; /* Used only for sizeof array */ | |
2182 | ||
2183 | /* zero length can cause confusions */ | |
2184 | if (!length) | |
2185 | length = 1; | |
2186 | ||
2271048d | 2187 | if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) |
7a8e76a3 SR |
2188 | length += sizeof(event.array[0]); |
2189 | ||
2190 | length += RB_EVNT_HDR_SIZE; | |
2271048d | 2191 | length = ALIGN(length, RB_ARCH_ALIGNMENT); |
7a8e76a3 SR |
2192 | |
2193 | return length; | |
2194 | } | |
2195 | ||
c7b09308 SR |
2196 | static inline void |
2197 | rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer, | |
2198 | struct buffer_page *tail_page, | |
2199 | unsigned long tail, unsigned long length) | |
2200 | { | |
2201 | struct ring_buffer_event *event; | |
2202 | ||
2203 | /* | |
2204 | * Only the event that crossed the page boundary | |
2205 | * must fill the old tail_page with padding. | |
2206 | */ | |
2207 | if (tail >= BUF_PAGE_SIZE) { | |
b3230c8b SR |
2208 | /* |
2209 | * If the page was filled, then we still need | |
2210 | * to update the real_end. Reset it to zero | |
2211 | * and the reader will ignore it. | |
2212 | */ | |
2213 | if (tail == BUF_PAGE_SIZE) | |
2214 | tail_page->real_end = 0; | |
2215 | ||
c7b09308 SR |
2216 | local_sub(length, &tail_page->write); |
2217 | return; | |
2218 | } | |
2219 | ||
2220 | event = __rb_page_index(tail_page, tail); | |
b0b7065b | 2221 | kmemcheck_annotate_bitfield(event, bitfield); |
c7b09308 | 2222 | |
c64e148a VN |
2223 | /* account for padding bytes */ |
2224 | local_add(BUF_PAGE_SIZE - tail, &cpu_buffer->entries_bytes); | |
2225 | ||
ff0ff84a SR |
2226 | /* |
2227 | * Save the original length to the meta data. | |
2228 | * This will be used by the reader to add lost event | |
2229 | * counter. | |
2230 | */ | |
2231 | tail_page->real_end = tail; | |
2232 | ||
c7b09308 SR |
2233 | /* |
2234 | * If this event is bigger than the minimum size, then | |
2235 | * we need to be careful that we don't subtract the | |
2236 | * write counter enough to allow another writer to slip | |
2237 | * in on this page. | |
2238 | * We put in a discarded commit instead, to make sure | |
2239 | * that this space is not used again. | |
2240 | * | |
2241 | * If we are less than the minimum size, we don't need to | |
2242 | * worry about it. | |
2243 | */ | |
2244 | if (tail > (BUF_PAGE_SIZE - RB_EVNT_MIN_SIZE)) { | |
2245 | /* No room for any events */ | |
2246 | ||
2247 | /* Mark the rest of the page with padding */ | |
2248 | rb_event_set_padding(event); | |
2249 | ||
2250 | /* Set the write back to the previous setting */ | |
2251 | local_sub(length, &tail_page->write); | |
2252 | return; | |
2253 | } | |
2254 | ||
2255 | /* Put in a discarded event */ | |
2256 | event->array[0] = (BUF_PAGE_SIZE - tail) - RB_EVNT_HDR_SIZE; | |
2257 | event->type_len = RINGBUF_TYPE_PADDING; | |
2258 | /* time delta must be non zero */ | |
2259 | event->time_delta = 1; | |
c7b09308 SR |
2260 | |
2261 | /* Set write to end of buffer */ | |
2262 | length = (tail + length) - BUF_PAGE_SIZE; | |
2263 | local_sub(length, &tail_page->write); | |
2264 | } | |
6634ff26 | 2265 | |
747e94ae SR |
2266 | /* |
2267 | * This is the slow path, force gcc not to inline it. | |
2268 | */ | |
2269 | static noinline struct ring_buffer_event * | |
6634ff26 SR |
2270 | rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer, |
2271 | unsigned long length, unsigned long tail, | |
e8bc43e8 | 2272 | struct buffer_page *tail_page, u64 ts) |
7a8e76a3 | 2273 | { |
5a50e33c | 2274 | struct buffer_page *commit_page = cpu_buffer->commit_page; |
7a8e76a3 | 2275 | struct ring_buffer *buffer = cpu_buffer->buffer; |
77ae365e SR |
2276 | struct buffer_page *next_page; |
2277 | int ret; | |
aa20ae84 SR |
2278 | |
2279 | next_page = tail_page; | |
2280 | ||
aa20ae84 SR |
2281 | rb_inc_page(cpu_buffer, &next_page); |
2282 | ||
aa20ae84 SR |
2283 | /* |
2284 | * If for some reason, we had an interrupt storm that made | |
2285 | * it all the way around the buffer, bail, and warn | |
2286 | * about it. | |
2287 | */ | |
2288 | if (unlikely(next_page == commit_page)) { | |
77ae365e | 2289 | local_inc(&cpu_buffer->commit_overrun); |
aa20ae84 SR |
2290 | goto out_reset; |
2291 | } | |
2292 | ||
77ae365e SR |
2293 | /* |
2294 | * This is where the fun begins! | |
2295 | * | |
2296 | * We are fighting against races between a reader that | |
2297 | * could be on another CPU trying to swap its reader | |
2298 | * page with the buffer head. | |
2299 | * | |
2300 | * We are also fighting against interrupts coming in and | |
2301 | * moving the head or tail on us as well. | |
2302 | * | |
2303 | * If the next page is the head page then we have filled | |
2304 | * the buffer, unless the commit page is still on the | |
2305 | * reader page. | |
2306 | */ | |
2307 | if (rb_is_head_page(cpu_buffer, next_page, &tail_page->list)) { | |
aa20ae84 | 2308 | |
77ae365e SR |
2309 | /* |
2310 | * If the commit is not on the reader page, then | |
2311 | * move the header page. | |
2312 | */ | |
2313 | if (!rb_is_reader_page(cpu_buffer->commit_page)) { | |
2314 | /* | |
2315 | * If we are not in overwrite mode, | |
2316 | * this is easy, just stop here. | |
2317 | */ | |
884bfe89 SP |
2318 | if (!(buffer->flags & RB_FL_OVERWRITE)) { |
2319 | local_inc(&cpu_buffer->dropped_events); | |
77ae365e | 2320 | goto out_reset; |
884bfe89 | 2321 | } |
77ae365e SR |
2322 | |
2323 | ret = rb_handle_head_page(cpu_buffer, | |
2324 | tail_page, | |
2325 | next_page); | |
2326 | if (ret < 0) | |
2327 | goto out_reset; | |
2328 | if (ret) | |
2329 | goto out_again; | |
2330 | } else { | |
2331 | /* | |
2332 | * We need to be careful here too. The | |
2333 | * commit page could still be on the reader | |
2334 | * page. We could have a small buffer, and | |
2335 | * have filled up the buffer with events | |
2336 | * from interrupts and such, and wrapped. | |
2337 | * | |
2338 | * Note, if the tail page is also the on the | |
2339 | * reader_page, we let it move out. | |
2340 | */ | |
2341 | if (unlikely((cpu_buffer->commit_page != | |
2342 | cpu_buffer->tail_page) && | |
2343 | (cpu_buffer->commit_page == | |
2344 | cpu_buffer->reader_page))) { | |
2345 | local_inc(&cpu_buffer->commit_overrun); | |
2346 | goto out_reset; | |
2347 | } | |
aa20ae84 SR |
2348 | } |
2349 | } | |
2350 | ||
77ae365e SR |
2351 | ret = rb_tail_page_update(cpu_buffer, tail_page, next_page); |
2352 | if (ret) { | |
2353 | /* | |
2354 | * Nested commits always have zero deltas, so | |
2355 | * just reread the time stamp | |
2356 | */ | |
e8bc43e8 SR |
2357 | ts = rb_time_stamp(buffer); |
2358 | next_page->page->time_stamp = ts; | |
aa20ae84 SR |
2359 | } |
2360 | ||
77ae365e | 2361 | out_again: |
aa20ae84 | 2362 | |
77ae365e | 2363 | rb_reset_tail(cpu_buffer, tail_page, tail, length); |
aa20ae84 SR |
2364 | |
2365 | /* fail and let the caller try again */ | |
2366 | return ERR_PTR(-EAGAIN); | |
2367 | ||
45141d46 | 2368 | out_reset: |
6f3b3440 | 2369 | /* reset write */ |
c7b09308 | 2370 | rb_reset_tail(cpu_buffer, tail_page, tail, length); |
6f3b3440 | 2371 | |
bf41a158 | 2372 | return NULL; |
7a8e76a3 SR |
2373 | } |
2374 | ||
6634ff26 SR |
2375 | static struct ring_buffer_event * |
2376 | __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, | |
69d1b839 SR |
2377 | unsigned long length, u64 ts, |
2378 | u64 delta, int add_timestamp) | |
6634ff26 | 2379 | { |
5a50e33c | 2380 | struct buffer_page *tail_page; |
6634ff26 SR |
2381 | struct ring_buffer_event *event; |
2382 | unsigned long tail, write; | |
2383 | ||
69d1b839 SR |
2384 | /* |
2385 | * If the time delta since the last event is too big to | |
2386 | * hold in the time field of the event, then we append a | |
2387 | * TIME EXTEND event ahead of the data event. | |
2388 | */ | |
2389 | if (unlikely(add_timestamp)) | |
2390 | length += RB_LEN_TIME_EXTEND; | |
2391 | ||
6634ff26 SR |
2392 | tail_page = cpu_buffer->tail_page; |
2393 | write = local_add_return(length, &tail_page->write); | |
77ae365e SR |
2394 | |
2395 | /* set write to only the index of the write */ | |
2396 | write &= RB_WRITE_MASK; | |
6634ff26 SR |
2397 | tail = write - length; |
2398 | ||
2399 | /* See if we shot pass the end of this buffer page */ | |
747e94ae | 2400 | if (unlikely(write > BUF_PAGE_SIZE)) |
6634ff26 | 2401 | return rb_move_tail(cpu_buffer, length, tail, |
5a50e33c | 2402 | tail_page, ts); |
6634ff26 SR |
2403 | |
2404 | /* We reserved something on the buffer */ | |
2405 | ||
6634ff26 | 2406 | event = __rb_page_index(tail_page, tail); |
1744a21d | 2407 | kmemcheck_annotate_bitfield(event, bitfield); |
69d1b839 | 2408 | rb_update_event(cpu_buffer, event, length, add_timestamp, delta); |
6634ff26 | 2409 | |
69d1b839 | 2410 | local_inc(&tail_page->entries); |
6634ff26 SR |
2411 | |
2412 | /* | |
fa743953 SR |
2413 | * If this is the first commit on the page, then update |
2414 | * its timestamp. | |
6634ff26 | 2415 | */ |
fa743953 | 2416 | if (!tail) |
e8bc43e8 | 2417 | tail_page->page->time_stamp = ts; |
6634ff26 | 2418 | |
c64e148a VN |
2419 | /* account for these added bytes */ |
2420 | local_add(length, &cpu_buffer->entries_bytes); | |
2421 | ||
6634ff26 SR |
2422 | return event; |
2423 | } | |
2424 | ||
edd813bf SR |
2425 | static inline int |
2426 | rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer, | |
2427 | struct ring_buffer_event *event) | |
2428 | { | |
2429 | unsigned long new_index, old_index; | |
2430 | struct buffer_page *bpage; | |
2431 | unsigned long index; | |
2432 | unsigned long addr; | |
2433 | ||
2434 | new_index = rb_event_index(event); | |
69d1b839 | 2435 | old_index = new_index + rb_event_ts_length(event); |
edd813bf SR |
2436 | addr = (unsigned long)event; |
2437 | addr &= PAGE_MASK; | |
2438 | ||
2439 | bpage = cpu_buffer->tail_page; | |
2440 | ||
2441 | if (bpage->page == (void *)addr && rb_page_write(bpage) == old_index) { | |
77ae365e SR |
2442 | unsigned long write_mask = |
2443 | local_read(&bpage->write) & ~RB_WRITE_MASK; | |
c64e148a | 2444 | unsigned long event_length = rb_event_length(event); |
edd813bf SR |
2445 | /* |
2446 | * This is on the tail page. It is possible that | |
2447 | * a write could come in and move the tail page | |
2448 | * and write to the next page. That is fine | |
2449 | * because we just shorten what is on this page. | |
2450 | */ | |
77ae365e SR |
2451 | old_index += write_mask; |
2452 | new_index += write_mask; | |
edd813bf | 2453 | index = local_cmpxchg(&bpage->write, old_index, new_index); |
c64e148a VN |
2454 | if (index == old_index) { |
2455 | /* update counters */ | |
2456 | local_sub(event_length, &cpu_buffer->entries_bytes); | |
edd813bf | 2457 | return 1; |
c64e148a | 2458 | } |
edd813bf SR |
2459 | } |
2460 | ||
2461 | /* could not discard */ | |
2462 | return 0; | |
2463 | } | |
2464 | ||
fa743953 SR |
2465 | static void rb_start_commit(struct ring_buffer_per_cpu *cpu_buffer) |
2466 | { | |
2467 | local_inc(&cpu_buffer->committing); | |
2468 | local_inc(&cpu_buffer->commits); | |
2469 | } | |
2470 | ||
d9abde21 | 2471 | static inline void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer) |
fa743953 SR |
2472 | { |
2473 | unsigned long commits; | |
2474 | ||
2475 | if (RB_WARN_ON(cpu_buffer, | |
2476 | !local_read(&cpu_buffer->committing))) | |
2477 | return; | |
2478 | ||
2479 | again: | |
2480 | commits = local_read(&cpu_buffer->commits); | |
2481 | /* synchronize with interrupts */ | |
2482 | barrier(); | |
2483 | if (local_read(&cpu_buffer->committing) == 1) | |
2484 | rb_set_commit_to_write(cpu_buffer); | |
2485 | ||
2486 | local_dec(&cpu_buffer->committing); | |
2487 | ||
2488 | /* synchronize with interrupts */ | |
2489 | barrier(); | |
2490 | ||
2491 | /* | |
2492 | * Need to account for interrupts coming in between the | |
2493 | * updating of the commit page and the clearing of the | |
2494 | * committing counter. | |
2495 | */ | |
2496 | if (unlikely(local_read(&cpu_buffer->commits) != commits) && | |
2497 | !local_read(&cpu_buffer->committing)) { | |
2498 | local_inc(&cpu_buffer->committing); | |
2499 | goto again; | |
2500 | } | |
2501 | } | |
2502 | ||
7a8e76a3 | 2503 | static struct ring_buffer_event * |
62f0b3eb SR |
2504 | rb_reserve_next_event(struct ring_buffer *buffer, |
2505 | struct ring_buffer_per_cpu *cpu_buffer, | |
1cd8d735 | 2506 | unsigned long length) |
7a8e76a3 SR |
2507 | { |
2508 | struct ring_buffer_event *event; | |
69d1b839 | 2509 | u64 ts, delta; |
818e3dd3 | 2510 | int nr_loops = 0; |
69d1b839 | 2511 | int add_timestamp; |
140ff891 | 2512 | u64 diff; |
7a8e76a3 | 2513 | |
fa743953 SR |
2514 | rb_start_commit(cpu_buffer); |
2515 | ||
85bac32c | 2516 | #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP |
62f0b3eb SR |
2517 | /* |
2518 | * Due to the ability to swap a cpu buffer from a buffer | |
2519 | * it is possible it was swapped before we committed. | |
2520 | * (committing stops a swap). We check for it here and | |
2521 | * if it happened, we have to fail the write. | |
2522 | */ | |
2523 | barrier(); | |
2524 | if (unlikely(ACCESS_ONCE(cpu_buffer->buffer) != buffer)) { | |
2525 | local_dec(&cpu_buffer->committing); | |
2526 | local_dec(&cpu_buffer->commits); | |
2527 | return NULL; | |
2528 | } | |
85bac32c | 2529 | #endif |
62f0b3eb | 2530 | |
be957c44 | 2531 | length = rb_calculate_event_length(length); |
bf41a158 | 2532 | again: |
69d1b839 SR |
2533 | add_timestamp = 0; |
2534 | delta = 0; | |
2535 | ||
818e3dd3 SR |
2536 | /* |
2537 | * We allow for interrupts to reenter here and do a trace. | |
2538 | * If one does, it will cause this original code to loop | |
2539 | * back here. Even with heavy interrupts happening, this | |
2540 | * should only happen a few times in a row. If this happens | |
2541 | * 1000 times in a row, there must be either an interrupt | |
2542 | * storm or we have something buggy. | |
2543 | * Bail! | |
2544 | */ | |
3e89c7bb | 2545 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000)) |
fa743953 | 2546 | goto out_fail; |
818e3dd3 | 2547 | |
6d3f1e12 | 2548 | ts = rb_time_stamp(cpu_buffer->buffer); |
140ff891 | 2549 | diff = ts - cpu_buffer->write_stamp; |
7a8e76a3 | 2550 | |
140ff891 SR |
2551 | /* make sure this diff is calculated here */ |
2552 | barrier(); | |
bf41a158 | 2553 | |
140ff891 SR |
2554 | /* Did the write stamp get updated already? */ |
2555 | if (likely(ts >= cpu_buffer->write_stamp)) { | |
168b6b1d SR |
2556 | delta = diff; |
2557 | if (unlikely(test_time_stamp(delta))) { | |
31274d72 JO |
2558 | int local_clock_stable = 1; |
2559 | #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK | |
2560 | local_clock_stable = sched_clock_stable; | |
2561 | #endif | |
69d1b839 | 2562 | WARN_ONCE(delta > (1ULL << 59), |
31274d72 | 2563 | KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n%s", |
69d1b839 SR |
2564 | (unsigned long long)delta, |
2565 | (unsigned long long)ts, | |
31274d72 JO |
2566 | (unsigned long long)cpu_buffer->write_stamp, |
2567 | local_clock_stable ? "" : | |
2568 | "If you just came from a suspend/resume,\n" | |
2569 | "please switch to the trace global clock:\n" | |
2570 | " echo global > /sys/kernel/debug/tracing/trace_clock\n"); | |
69d1b839 | 2571 | add_timestamp = 1; |
7a8e76a3 | 2572 | } |
168b6b1d | 2573 | } |
7a8e76a3 | 2574 | |
69d1b839 SR |
2575 | event = __rb_reserve_next(cpu_buffer, length, ts, |
2576 | delta, add_timestamp); | |
168b6b1d | 2577 | if (unlikely(PTR_ERR(event) == -EAGAIN)) |
bf41a158 SR |
2578 | goto again; |
2579 | ||
fa743953 SR |
2580 | if (!event) |
2581 | goto out_fail; | |
7a8e76a3 | 2582 | |
7a8e76a3 | 2583 | return event; |
fa743953 SR |
2584 | |
2585 | out_fail: | |
2586 | rb_end_commit(cpu_buffer); | |
2587 | return NULL; | |
7a8e76a3 SR |
2588 | } |
2589 | ||
1155de47 PM |
2590 | #ifdef CONFIG_TRACING |
2591 | ||
567cd4da SR |
2592 | /* |
2593 | * The lock and unlock are done within a preempt disable section. | |
2594 | * The current_context per_cpu variable can only be modified | |
2595 | * by the current task between lock and unlock. But it can | |
2596 | * be modified more than once via an interrupt. To pass this | |
2597 | * information from the lock to the unlock without having to | |
2598 | * access the 'in_interrupt()' functions again (which do show | |
2599 | * a bit of overhead in something as critical as function tracing, | |
2600 | * we use a bitmask trick. | |
2601 | * | |
2602 | * bit 0 = NMI context | |
2603 | * bit 1 = IRQ context | |
2604 | * bit 2 = SoftIRQ context | |
2605 | * bit 3 = normal context. | |
2606 | * | |
2607 | * This works because this is the order of contexts that can | |
2608 | * preempt other contexts. A SoftIRQ never preempts an IRQ | |
2609 | * context. | |
2610 | * | |
2611 | * When the context is determined, the corresponding bit is | |
2612 | * checked and set (if it was set, then a recursion of that context | |
2613 | * happened). | |
2614 | * | |
2615 | * On unlock, we need to clear this bit. To do so, just subtract | |
2616 | * 1 from the current_context and AND it to itself. | |
2617 | * | |
2618 | * (binary) | |
2619 | * 101 - 1 = 100 | |
2620 | * 101 & 100 = 100 (clearing bit zero) | |
2621 | * | |
2622 | * 1010 - 1 = 1001 | |
2623 | * 1010 & 1001 = 1000 (clearing bit 1) | |
2624 | * | |
2625 | * The least significant bit can be cleared this way, and it | |
2626 | * just so happens that it is the same bit corresponding to | |
2627 | * the current context. | |
2628 | */ | |
2629 | static DEFINE_PER_CPU(unsigned int, current_context); | |
261842b7 | 2630 | |
567cd4da | 2631 | static __always_inline int trace_recursive_lock(void) |
261842b7 | 2632 | { |
567cd4da SR |
2633 | unsigned int val = this_cpu_read(current_context); |
2634 | int bit; | |
d9abde21 | 2635 | |
567cd4da SR |
2636 | if (in_interrupt()) { |
2637 | if (in_nmi()) | |
2638 | bit = 0; | |
2639 | else if (in_irq()) | |
2640 | bit = 1; | |
2641 | else | |
2642 | bit = 2; | |
2643 | } else | |
2644 | bit = 3; | |
d9abde21 | 2645 | |
567cd4da SR |
2646 | if (unlikely(val & (1 << bit))) |
2647 | return 1; | |
d9abde21 | 2648 | |
567cd4da SR |
2649 | val |= (1 << bit); |
2650 | this_cpu_write(current_context, val); | |
d9abde21 | 2651 | |
567cd4da | 2652 | return 0; |
261842b7 SR |
2653 | } |
2654 | ||
567cd4da | 2655 | static __always_inline void trace_recursive_unlock(void) |
261842b7 | 2656 | { |
567cd4da | 2657 | unsigned int val = this_cpu_read(current_context); |
261842b7 | 2658 | |
567cd4da SR |
2659 | val--; |
2660 | val &= this_cpu_read(current_context); | |
2661 | this_cpu_write(current_context, val); | |
261842b7 SR |
2662 | } |
2663 | ||
1155de47 PM |
2664 | #else |
2665 | ||
2666 | #define trace_recursive_lock() (0) | |
2667 | #define trace_recursive_unlock() do { } while (0) | |
2668 | ||
2669 | #endif | |
2670 | ||
7a8e76a3 SR |
2671 | /** |
2672 | * ring_buffer_lock_reserve - reserve a part of the buffer | |
2673 | * @buffer: the ring buffer to reserve from | |
2674 | * @length: the length of the data to reserve (excluding event header) | |
7a8e76a3 SR |
2675 | * |
2676 | * Returns a reseverd event on the ring buffer to copy directly to. | |
2677 | * The user of this interface will need to get the body to write into | |
2678 | * and can use the ring_buffer_event_data() interface. | |
2679 | * | |
2680 | * The length is the length of the data needed, not the event length | |
2681 | * which also includes the event header. | |
2682 | * | |
2683 | * Must be paired with ring_buffer_unlock_commit, unless NULL is returned. | |
2684 | * If NULL is returned, then nothing has been allocated or locked. | |
2685 | */ | |
2686 | struct ring_buffer_event * | |
0a987751 | 2687 | ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length) |
7a8e76a3 SR |
2688 | { |
2689 | struct ring_buffer_per_cpu *cpu_buffer; | |
2690 | struct ring_buffer_event *event; | |
5168ae50 | 2691 | int cpu; |
7a8e76a3 | 2692 | |
033601a3 | 2693 | if (ring_buffer_flags != RB_BUFFERS_ON) |
a3583244 SR |
2694 | return NULL; |
2695 | ||
bf41a158 | 2696 | /* If we are tracing schedule, we don't want to recurse */ |
5168ae50 | 2697 | preempt_disable_notrace(); |
bf41a158 | 2698 | |
52fbe9cd LJ |
2699 | if (atomic_read(&buffer->record_disabled)) |
2700 | goto out_nocheck; | |
2701 | ||
261842b7 SR |
2702 | if (trace_recursive_lock()) |
2703 | goto out_nocheck; | |
2704 | ||
7a8e76a3 SR |
2705 | cpu = raw_smp_processor_id(); |
2706 | ||
9e01c1b7 | 2707 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
d769041f | 2708 | goto out; |
7a8e76a3 SR |
2709 | |
2710 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 SR |
2711 | |
2712 | if (atomic_read(&cpu_buffer->record_disabled)) | |
d769041f | 2713 | goto out; |
7a8e76a3 | 2714 | |
be957c44 | 2715 | if (length > BUF_MAX_DATA_SIZE) |
bf41a158 | 2716 | goto out; |
7a8e76a3 | 2717 | |
62f0b3eb | 2718 | event = rb_reserve_next_event(buffer, cpu_buffer, length); |
7a8e76a3 | 2719 | if (!event) |
d769041f | 2720 | goto out; |
7a8e76a3 SR |
2721 | |
2722 | return event; | |
2723 | ||
d769041f | 2724 | out: |
261842b7 SR |
2725 | trace_recursive_unlock(); |
2726 | ||
2727 | out_nocheck: | |
5168ae50 | 2728 | preempt_enable_notrace(); |
7a8e76a3 SR |
2729 | return NULL; |
2730 | } | |
c4f50183 | 2731 | EXPORT_SYMBOL_GPL(ring_buffer_lock_reserve); |
7a8e76a3 | 2732 | |
a1863c21 SR |
2733 | static void |
2734 | rb_update_write_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
7a8e76a3 SR |
2735 | struct ring_buffer_event *event) |
2736 | { | |
69d1b839 SR |
2737 | u64 delta; |
2738 | ||
fa743953 SR |
2739 | /* |
2740 | * The event first in the commit queue updates the | |
2741 | * time stamp. | |
2742 | */ | |
69d1b839 SR |
2743 | if (rb_event_is_commit(cpu_buffer, event)) { |
2744 | /* | |
2745 | * A commit event that is first on a page | |
2746 | * updates the write timestamp with the page stamp | |
2747 | */ | |
2748 | if (!rb_event_index(event)) | |
2749 | cpu_buffer->write_stamp = | |
2750 | cpu_buffer->commit_page->page->time_stamp; | |
2751 | else if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) { | |
2752 | delta = event->array[0]; | |
2753 | delta <<= TS_SHIFT; | |
2754 | delta += event->time_delta; | |
2755 | cpu_buffer->write_stamp += delta; | |
2756 | } else | |
2757 | cpu_buffer->write_stamp += event->time_delta; | |
2758 | } | |
a1863c21 | 2759 | } |
bf41a158 | 2760 | |
a1863c21 SR |
2761 | static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, |
2762 | struct ring_buffer_event *event) | |
2763 | { | |
2764 | local_inc(&cpu_buffer->entries); | |
2765 | rb_update_write_stamp(cpu_buffer, event); | |
fa743953 | 2766 | rb_end_commit(cpu_buffer); |
7a8e76a3 SR |
2767 | } |
2768 | ||
15693458 SRRH |
2769 | static __always_inline void |
2770 | rb_wakeups(struct ring_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer) | |
2771 | { | |
2772 | if (buffer->irq_work.waiters_pending) { | |
2773 | buffer->irq_work.waiters_pending = false; | |
2774 | /* irq_work_queue() supplies it's own memory barriers */ | |
2775 | irq_work_queue(&buffer->irq_work.work); | |
2776 | } | |
2777 | ||
2778 | if (cpu_buffer->irq_work.waiters_pending) { | |
2779 | cpu_buffer->irq_work.waiters_pending = false; | |
2780 | /* irq_work_queue() supplies it's own memory barriers */ | |
2781 | irq_work_queue(&cpu_buffer->irq_work.work); | |
2782 | } | |
2783 | } | |
2784 | ||
7a8e76a3 SR |
2785 | /** |
2786 | * ring_buffer_unlock_commit - commit a reserved | |
2787 | * @buffer: The buffer to commit to | |
2788 | * @event: The event pointer to commit. | |
7a8e76a3 SR |
2789 | * |
2790 | * This commits the data to the ring buffer, and releases any locks held. | |
2791 | * | |
2792 | * Must be paired with ring_buffer_lock_reserve. | |
2793 | */ | |
2794 | int ring_buffer_unlock_commit(struct ring_buffer *buffer, | |
0a987751 | 2795 | struct ring_buffer_event *event) |
7a8e76a3 SR |
2796 | { |
2797 | struct ring_buffer_per_cpu *cpu_buffer; | |
2798 | int cpu = raw_smp_processor_id(); | |
2799 | ||
2800 | cpu_buffer = buffer->buffers[cpu]; | |
2801 | ||
7a8e76a3 SR |
2802 | rb_commit(cpu_buffer, event); |
2803 | ||
15693458 SRRH |
2804 | rb_wakeups(buffer, cpu_buffer); |
2805 | ||
261842b7 SR |
2806 | trace_recursive_unlock(); |
2807 | ||
5168ae50 | 2808 | preempt_enable_notrace(); |
7a8e76a3 SR |
2809 | |
2810 | return 0; | |
2811 | } | |
c4f50183 | 2812 | EXPORT_SYMBOL_GPL(ring_buffer_unlock_commit); |
7a8e76a3 | 2813 | |
f3b9aae1 FW |
2814 | static inline void rb_event_discard(struct ring_buffer_event *event) |
2815 | { | |
69d1b839 SR |
2816 | if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) |
2817 | event = skip_time_extend(event); | |
2818 | ||
334d4169 LJ |
2819 | /* array[0] holds the actual length for the discarded event */ |
2820 | event->array[0] = rb_event_data_length(event) - RB_EVNT_HDR_SIZE; | |
2821 | event->type_len = RINGBUF_TYPE_PADDING; | |
f3b9aae1 FW |
2822 | /* time delta must be non zero */ |
2823 | if (!event->time_delta) | |
2824 | event->time_delta = 1; | |
2825 | } | |
2826 | ||
a1863c21 SR |
2827 | /* |
2828 | * Decrement the entries to the page that an event is on. | |
2829 | * The event does not even need to exist, only the pointer | |
2830 | * to the page it is on. This may only be called before the commit | |
2831 | * takes place. | |
2832 | */ | |
2833 | static inline void | |
2834 | rb_decrement_entry(struct ring_buffer_per_cpu *cpu_buffer, | |
2835 | struct ring_buffer_event *event) | |
2836 | { | |
2837 | unsigned long addr = (unsigned long)event; | |
2838 | struct buffer_page *bpage = cpu_buffer->commit_page; | |
2839 | struct buffer_page *start; | |
2840 | ||
2841 | addr &= PAGE_MASK; | |
2842 | ||
2843 | /* Do the likely case first */ | |
2844 | if (likely(bpage->page == (void *)addr)) { | |
2845 | local_dec(&bpage->entries); | |
2846 | return; | |
2847 | } | |
2848 | ||
2849 | /* | |
2850 | * Because the commit page may be on the reader page we | |
2851 | * start with the next page and check the end loop there. | |
2852 | */ | |
2853 | rb_inc_page(cpu_buffer, &bpage); | |
2854 | start = bpage; | |
2855 | do { | |
2856 | if (bpage->page == (void *)addr) { | |
2857 | local_dec(&bpage->entries); | |
2858 | return; | |
2859 | } | |
2860 | rb_inc_page(cpu_buffer, &bpage); | |
2861 | } while (bpage != start); | |
2862 | ||
2863 | /* commit not part of this buffer?? */ | |
2864 | RB_WARN_ON(cpu_buffer, 1); | |
2865 | } | |
2866 | ||
fa1b47dd SR |
2867 | /** |
2868 | * ring_buffer_commit_discard - discard an event that has not been committed | |
2869 | * @buffer: the ring buffer | |
2870 | * @event: non committed event to discard | |
2871 | * | |
dc892f73 SR |
2872 | * Sometimes an event that is in the ring buffer needs to be ignored. |
2873 | * This function lets the user discard an event in the ring buffer | |
2874 | * and then that event will not be read later. | |
2875 | * | |
2876 | * This function only works if it is called before the the item has been | |
2877 | * committed. It will try to free the event from the ring buffer | |
fa1b47dd SR |
2878 | * if another event has not been added behind it. |
2879 | * | |
2880 | * If another event has been added behind it, it will set the event | |
2881 | * up as discarded, and perform the commit. | |
2882 | * | |
2883 | * If this function is called, do not call ring_buffer_unlock_commit on | |
2884 | * the event. | |
2885 | */ | |
2886 | void ring_buffer_discard_commit(struct ring_buffer *buffer, | |
2887 | struct ring_buffer_event *event) | |
2888 | { | |
2889 | struct ring_buffer_per_cpu *cpu_buffer; | |
fa1b47dd SR |
2890 | int cpu; |
2891 | ||
2892 | /* The event is discarded regardless */ | |
f3b9aae1 | 2893 | rb_event_discard(event); |
fa1b47dd | 2894 | |
fa743953 SR |
2895 | cpu = smp_processor_id(); |
2896 | cpu_buffer = buffer->buffers[cpu]; | |
2897 | ||
fa1b47dd SR |
2898 | /* |
2899 | * This must only be called if the event has not been | |
2900 | * committed yet. Thus we can assume that preemption | |
2901 | * is still disabled. | |
2902 | */ | |
fa743953 | 2903 | RB_WARN_ON(buffer, !local_read(&cpu_buffer->committing)); |
fa1b47dd | 2904 | |
a1863c21 | 2905 | rb_decrement_entry(cpu_buffer, event); |
0f2541d2 | 2906 | if (rb_try_to_discard(cpu_buffer, event)) |
edd813bf | 2907 | goto out; |
fa1b47dd SR |
2908 | |
2909 | /* | |
2910 | * The commit is still visible by the reader, so we | |
a1863c21 | 2911 | * must still update the timestamp. |
fa1b47dd | 2912 | */ |
a1863c21 | 2913 | rb_update_write_stamp(cpu_buffer, event); |
fa1b47dd | 2914 | out: |
fa743953 | 2915 | rb_end_commit(cpu_buffer); |
fa1b47dd | 2916 | |
f3b9aae1 FW |
2917 | trace_recursive_unlock(); |
2918 | ||
5168ae50 | 2919 | preempt_enable_notrace(); |
fa1b47dd SR |
2920 | |
2921 | } | |
2922 | EXPORT_SYMBOL_GPL(ring_buffer_discard_commit); | |
2923 | ||
7a8e76a3 SR |
2924 | /** |
2925 | * ring_buffer_write - write data to the buffer without reserving | |
2926 | * @buffer: The ring buffer to write to. | |
2927 | * @length: The length of the data being written (excluding the event header) | |
2928 | * @data: The data to write to the buffer. | |
2929 | * | |
2930 | * This is like ring_buffer_lock_reserve and ring_buffer_unlock_commit as | |
2931 | * one function. If you already have the data to write to the buffer, it | |
2932 | * may be easier to simply call this function. | |
2933 | * | |
2934 | * Note, like ring_buffer_lock_reserve, the length is the length of the data | |
2935 | * and not the length of the event which would hold the header. | |
2936 | */ | |
2937 | int ring_buffer_write(struct ring_buffer *buffer, | |
01e3e710 DS |
2938 | unsigned long length, |
2939 | void *data) | |
7a8e76a3 SR |
2940 | { |
2941 | struct ring_buffer_per_cpu *cpu_buffer; | |
2942 | struct ring_buffer_event *event; | |
7a8e76a3 SR |
2943 | void *body; |
2944 | int ret = -EBUSY; | |
5168ae50 | 2945 | int cpu; |
7a8e76a3 | 2946 | |
033601a3 | 2947 | if (ring_buffer_flags != RB_BUFFERS_ON) |
a3583244 SR |
2948 | return -EBUSY; |
2949 | ||
5168ae50 | 2950 | preempt_disable_notrace(); |
bf41a158 | 2951 | |
52fbe9cd LJ |
2952 | if (atomic_read(&buffer->record_disabled)) |
2953 | goto out; | |
2954 | ||
7a8e76a3 SR |
2955 | cpu = raw_smp_processor_id(); |
2956 | ||
9e01c1b7 | 2957 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
d769041f | 2958 | goto out; |
7a8e76a3 SR |
2959 | |
2960 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 SR |
2961 | |
2962 | if (atomic_read(&cpu_buffer->record_disabled)) | |
2963 | goto out; | |
2964 | ||
be957c44 SR |
2965 | if (length > BUF_MAX_DATA_SIZE) |
2966 | goto out; | |
2967 | ||
62f0b3eb | 2968 | event = rb_reserve_next_event(buffer, cpu_buffer, length); |
7a8e76a3 SR |
2969 | if (!event) |
2970 | goto out; | |
2971 | ||
2972 | body = rb_event_data(event); | |
2973 | ||
2974 | memcpy(body, data, length); | |
2975 | ||
2976 | rb_commit(cpu_buffer, event); | |
2977 | ||
15693458 SRRH |
2978 | rb_wakeups(buffer, cpu_buffer); |
2979 | ||
7a8e76a3 SR |
2980 | ret = 0; |
2981 | out: | |
5168ae50 | 2982 | preempt_enable_notrace(); |
7a8e76a3 SR |
2983 | |
2984 | return ret; | |
2985 | } | |
c4f50183 | 2986 | EXPORT_SYMBOL_GPL(ring_buffer_write); |
7a8e76a3 | 2987 | |
34a148bf | 2988 | static int rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) |
bf41a158 SR |
2989 | { |
2990 | struct buffer_page *reader = cpu_buffer->reader_page; | |
77ae365e | 2991 | struct buffer_page *head = rb_set_head_page(cpu_buffer); |
bf41a158 SR |
2992 | struct buffer_page *commit = cpu_buffer->commit_page; |
2993 | ||
77ae365e SR |
2994 | /* In case of error, head will be NULL */ |
2995 | if (unlikely(!head)) | |
2996 | return 1; | |
2997 | ||
bf41a158 SR |
2998 | return reader->read == rb_page_commit(reader) && |
2999 | (commit == reader || | |
3000 | (commit == head && | |
3001 | head->read == rb_page_commit(commit))); | |
3002 | } | |
3003 | ||
7a8e76a3 SR |
3004 | /** |
3005 | * ring_buffer_record_disable - stop all writes into the buffer | |
3006 | * @buffer: The ring buffer to stop writes to. | |
3007 | * | |
3008 | * This prevents all writes to the buffer. Any attempt to write | |
3009 | * to the buffer after this will fail and return NULL. | |
3010 | * | |
3011 | * The caller should call synchronize_sched() after this. | |
3012 | */ | |
3013 | void ring_buffer_record_disable(struct ring_buffer *buffer) | |
3014 | { | |
3015 | atomic_inc(&buffer->record_disabled); | |
3016 | } | |
c4f50183 | 3017 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable); |
7a8e76a3 SR |
3018 | |
3019 | /** | |
3020 | * ring_buffer_record_enable - enable writes to the buffer | |
3021 | * @buffer: The ring buffer to enable writes | |
3022 | * | |
3023 | * Note, multiple disables will need the same number of enables | |
c41b20e7 | 3024 | * to truly enable the writing (much like preempt_disable). |
7a8e76a3 SR |
3025 | */ |
3026 | void ring_buffer_record_enable(struct ring_buffer *buffer) | |
3027 | { | |
3028 | atomic_dec(&buffer->record_disabled); | |
3029 | } | |
c4f50183 | 3030 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable); |
7a8e76a3 | 3031 | |
499e5470 SR |
3032 | /** |
3033 | * ring_buffer_record_off - stop all writes into the buffer | |
3034 | * @buffer: The ring buffer to stop writes to. | |
3035 | * | |
3036 | * This prevents all writes to the buffer. Any attempt to write | |
3037 | * to the buffer after this will fail and return NULL. | |
3038 | * | |
3039 | * This is different than ring_buffer_record_disable() as | |
87abb3b1 | 3040 | * it works like an on/off switch, where as the disable() version |
499e5470 SR |
3041 | * must be paired with a enable(). |
3042 | */ | |
3043 | void ring_buffer_record_off(struct ring_buffer *buffer) | |
3044 | { | |
3045 | unsigned int rd; | |
3046 | unsigned int new_rd; | |
3047 | ||
3048 | do { | |
3049 | rd = atomic_read(&buffer->record_disabled); | |
3050 | new_rd = rd | RB_BUFFER_OFF; | |
3051 | } while (atomic_cmpxchg(&buffer->record_disabled, rd, new_rd) != rd); | |
3052 | } | |
3053 | EXPORT_SYMBOL_GPL(ring_buffer_record_off); | |
3054 | ||
3055 | /** | |
3056 | * ring_buffer_record_on - restart writes into the buffer | |
3057 | * @buffer: The ring buffer to start writes to. | |
3058 | * | |
3059 | * This enables all writes to the buffer that was disabled by | |
3060 | * ring_buffer_record_off(). | |
3061 | * | |
3062 | * This is different than ring_buffer_record_enable() as | |
87abb3b1 | 3063 | * it works like an on/off switch, where as the enable() version |
499e5470 SR |
3064 | * must be paired with a disable(). |
3065 | */ | |
3066 | void ring_buffer_record_on(struct ring_buffer *buffer) | |
3067 | { | |
3068 | unsigned int rd; | |
3069 | unsigned int new_rd; | |
3070 | ||
3071 | do { | |
3072 | rd = atomic_read(&buffer->record_disabled); | |
3073 | new_rd = rd & ~RB_BUFFER_OFF; | |
3074 | } while (atomic_cmpxchg(&buffer->record_disabled, rd, new_rd) != rd); | |
3075 | } | |
3076 | EXPORT_SYMBOL_GPL(ring_buffer_record_on); | |
3077 | ||
3078 | /** | |
3079 | * ring_buffer_record_is_on - return true if the ring buffer can write | |
3080 | * @buffer: The ring buffer to see if write is enabled | |
3081 | * | |
3082 | * Returns true if the ring buffer is in a state that it accepts writes. | |
3083 | */ | |
3084 | int ring_buffer_record_is_on(struct ring_buffer *buffer) | |
3085 | { | |
3086 | return !atomic_read(&buffer->record_disabled); | |
3087 | } | |
3088 | ||
7a8e76a3 SR |
3089 | /** |
3090 | * ring_buffer_record_disable_cpu - stop all writes into the cpu_buffer | |
3091 | * @buffer: The ring buffer to stop writes to. | |
3092 | * @cpu: The CPU buffer to stop | |
3093 | * | |
3094 | * This prevents all writes to the buffer. Any attempt to write | |
3095 | * to the buffer after this will fail and return NULL. | |
3096 | * | |
3097 | * The caller should call synchronize_sched() after this. | |
3098 | */ | |
3099 | void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu) | |
3100 | { | |
3101 | struct ring_buffer_per_cpu *cpu_buffer; | |
3102 | ||
9e01c1b7 | 3103 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 3104 | return; |
7a8e76a3 SR |
3105 | |
3106 | cpu_buffer = buffer->buffers[cpu]; | |
3107 | atomic_inc(&cpu_buffer->record_disabled); | |
3108 | } | |
c4f50183 | 3109 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable_cpu); |
7a8e76a3 SR |
3110 | |
3111 | /** | |
3112 | * ring_buffer_record_enable_cpu - enable writes to the buffer | |
3113 | * @buffer: The ring buffer to enable writes | |
3114 | * @cpu: The CPU to enable. | |
3115 | * | |
3116 | * Note, multiple disables will need the same number of enables | |
c41b20e7 | 3117 | * to truly enable the writing (much like preempt_disable). |
7a8e76a3 SR |
3118 | */ |
3119 | void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu) | |
3120 | { | |
3121 | struct ring_buffer_per_cpu *cpu_buffer; | |
3122 | ||
9e01c1b7 | 3123 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 3124 | return; |
7a8e76a3 SR |
3125 | |
3126 | cpu_buffer = buffer->buffers[cpu]; | |
3127 | atomic_dec(&cpu_buffer->record_disabled); | |
3128 | } | |
c4f50183 | 3129 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu); |
7a8e76a3 | 3130 | |
f6195aa0 SR |
3131 | /* |
3132 | * The total entries in the ring buffer is the running counter | |
3133 | * of entries entered into the ring buffer, minus the sum of | |
3134 | * the entries read from the ring buffer and the number of | |
3135 | * entries that were overwritten. | |
3136 | */ | |
3137 | static inline unsigned long | |
3138 | rb_num_of_entries(struct ring_buffer_per_cpu *cpu_buffer) | |
3139 | { | |
3140 | return local_read(&cpu_buffer->entries) - | |
3141 | (local_read(&cpu_buffer->overrun) + cpu_buffer->read); | |
3142 | } | |
3143 | ||
c64e148a VN |
3144 | /** |
3145 | * ring_buffer_oldest_event_ts - get the oldest event timestamp from the buffer | |
3146 | * @buffer: The ring buffer | |
3147 | * @cpu: The per CPU buffer to read from. | |
3148 | */ | |
50ecf2c3 | 3149 | u64 ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu) |
c64e148a VN |
3150 | { |
3151 | unsigned long flags; | |
3152 | struct ring_buffer_per_cpu *cpu_buffer; | |
3153 | struct buffer_page *bpage; | |
da830e58 | 3154 | u64 ret = 0; |
c64e148a VN |
3155 | |
3156 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
3157 | return 0; | |
3158 | ||
3159 | cpu_buffer = buffer->buffers[cpu]; | |
7115e3fc | 3160 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
c64e148a VN |
3161 | /* |
3162 | * if the tail is on reader_page, oldest time stamp is on the reader | |
3163 | * page | |
3164 | */ | |
3165 | if (cpu_buffer->tail_page == cpu_buffer->reader_page) | |
3166 | bpage = cpu_buffer->reader_page; | |
3167 | else | |
3168 | bpage = rb_set_head_page(cpu_buffer); | |
54f7be5b SR |
3169 | if (bpage) |
3170 | ret = bpage->page->time_stamp; | |
7115e3fc | 3171 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
c64e148a VN |
3172 | |
3173 | return ret; | |
3174 | } | |
3175 | EXPORT_SYMBOL_GPL(ring_buffer_oldest_event_ts); | |
3176 | ||
3177 | /** | |
3178 | * ring_buffer_bytes_cpu - get the number of bytes consumed in a cpu buffer | |
3179 | * @buffer: The ring buffer | |
3180 | * @cpu: The per CPU buffer to read from. | |
3181 | */ | |
3182 | unsigned long ring_buffer_bytes_cpu(struct ring_buffer *buffer, int cpu) | |
3183 | { | |
3184 | struct ring_buffer_per_cpu *cpu_buffer; | |
3185 | unsigned long ret; | |
3186 | ||
3187 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
3188 | return 0; | |
3189 | ||
3190 | cpu_buffer = buffer->buffers[cpu]; | |
3191 | ret = local_read(&cpu_buffer->entries_bytes) - cpu_buffer->read_bytes; | |
3192 | ||
3193 | return ret; | |
3194 | } | |
3195 | EXPORT_SYMBOL_GPL(ring_buffer_bytes_cpu); | |
3196 | ||
7a8e76a3 SR |
3197 | /** |
3198 | * ring_buffer_entries_cpu - get the number of entries in a cpu buffer | |
3199 | * @buffer: The ring buffer | |
3200 | * @cpu: The per CPU buffer to get the entries from. | |
3201 | */ | |
3202 | unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu) | |
3203 | { | |
3204 | struct ring_buffer_per_cpu *cpu_buffer; | |
3205 | ||
9e01c1b7 | 3206 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 3207 | return 0; |
7a8e76a3 SR |
3208 | |
3209 | cpu_buffer = buffer->buffers[cpu]; | |
554f786e | 3210 | |
f6195aa0 | 3211 | return rb_num_of_entries(cpu_buffer); |
7a8e76a3 | 3212 | } |
c4f50183 | 3213 | EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu); |
7a8e76a3 SR |
3214 | |
3215 | /** | |
884bfe89 SP |
3216 | * ring_buffer_overrun_cpu - get the number of overruns caused by the ring |
3217 | * buffer wrapping around (only if RB_FL_OVERWRITE is on). | |
7a8e76a3 SR |
3218 | * @buffer: The ring buffer |
3219 | * @cpu: The per CPU buffer to get the number of overruns from | |
3220 | */ | |
3221 | unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu) | |
3222 | { | |
3223 | struct ring_buffer_per_cpu *cpu_buffer; | |
8aabee57 | 3224 | unsigned long ret; |
7a8e76a3 | 3225 | |
9e01c1b7 | 3226 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 3227 | return 0; |
7a8e76a3 SR |
3228 | |
3229 | cpu_buffer = buffer->buffers[cpu]; | |
77ae365e | 3230 | ret = local_read(&cpu_buffer->overrun); |
554f786e SR |
3231 | |
3232 | return ret; | |
7a8e76a3 | 3233 | } |
c4f50183 | 3234 | EXPORT_SYMBOL_GPL(ring_buffer_overrun_cpu); |
7a8e76a3 | 3235 | |
f0d2c681 | 3236 | /** |
884bfe89 SP |
3237 | * ring_buffer_commit_overrun_cpu - get the number of overruns caused by |
3238 | * commits failing due to the buffer wrapping around while there are uncommitted | |
3239 | * events, such as during an interrupt storm. | |
f0d2c681 SR |
3240 | * @buffer: The ring buffer |
3241 | * @cpu: The per CPU buffer to get the number of overruns from | |
3242 | */ | |
3243 | unsigned long | |
3244 | ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu) | |
3245 | { | |
3246 | struct ring_buffer_per_cpu *cpu_buffer; | |
3247 | unsigned long ret; | |
3248 | ||
3249 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
3250 | return 0; | |
3251 | ||
3252 | cpu_buffer = buffer->buffers[cpu]; | |
77ae365e | 3253 | ret = local_read(&cpu_buffer->commit_overrun); |
f0d2c681 SR |
3254 | |
3255 | return ret; | |
3256 | } | |
3257 | EXPORT_SYMBOL_GPL(ring_buffer_commit_overrun_cpu); | |
3258 | ||
884bfe89 SP |
3259 | /** |
3260 | * ring_buffer_dropped_events_cpu - get the number of dropped events caused by | |
3261 | * the ring buffer filling up (only if RB_FL_OVERWRITE is off). | |
3262 | * @buffer: The ring buffer | |
3263 | * @cpu: The per CPU buffer to get the number of overruns from | |
3264 | */ | |
3265 | unsigned long | |
3266 | ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu) | |
3267 | { | |
3268 | struct ring_buffer_per_cpu *cpu_buffer; | |
3269 | unsigned long ret; | |
3270 | ||
3271 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
3272 | return 0; | |
3273 | ||
3274 | cpu_buffer = buffer->buffers[cpu]; | |
3275 | ret = local_read(&cpu_buffer->dropped_events); | |
3276 | ||
3277 | return ret; | |
3278 | } | |
3279 | EXPORT_SYMBOL_GPL(ring_buffer_dropped_events_cpu); | |
3280 | ||
ad964704 SRRH |
3281 | /** |
3282 | * ring_buffer_read_events_cpu - get the number of events successfully read | |
3283 | * @buffer: The ring buffer | |
3284 | * @cpu: The per CPU buffer to get the number of events read | |
3285 | */ | |
3286 | unsigned long | |
3287 | ring_buffer_read_events_cpu(struct ring_buffer *buffer, int cpu) | |
3288 | { | |
3289 | struct ring_buffer_per_cpu *cpu_buffer; | |
3290 | ||
3291 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
3292 | return 0; | |
3293 | ||
3294 | cpu_buffer = buffer->buffers[cpu]; | |
3295 | return cpu_buffer->read; | |
3296 | } | |
3297 | EXPORT_SYMBOL_GPL(ring_buffer_read_events_cpu); | |
3298 | ||
7a8e76a3 SR |
3299 | /** |
3300 | * ring_buffer_entries - get the number of entries in a buffer | |
3301 | * @buffer: The ring buffer | |
3302 | * | |
3303 | * Returns the total number of entries in the ring buffer | |
3304 | * (all CPU entries) | |
3305 | */ | |
3306 | unsigned long ring_buffer_entries(struct ring_buffer *buffer) | |
3307 | { | |
3308 | struct ring_buffer_per_cpu *cpu_buffer; | |
3309 | unsigned long entries = 0; | |
3310 | int cpu; | |
3311 | ||
3312 | /* if you care about this being correct, lock the buffer */ | |
3313 | for_each_buffer_cpu(buffer, cpu) { | |
3314 | cpu_buffer = buffer->buffers[cpu]; | |
f6195aa0 | 3315 | entries += rb_num_of_entries(cpu_buffer); |
7a8e76a3 SR |
3316 | } |
3317 | ||
3318 | return entries; | |
3319 | } | |
c4f50183 | 3320 | EXPORT_SYMBOL_GPL(ring_buffer_entries); |
7a8e76a3 SR |
3321 | |
3322 | /** | |
67b394f7 | 3323 | * ring_buffer_overruns - get the number of overruns in buffer |
7a8e76a3 SR |
3324 | * @buffer: The ring buffer |
3325 | * | |
3326 | * Returns the total number of overruns in the ring buffer | |
3327 | * (all CPU entries) | |
3328 | */ | |
3329 | unsigned long ring_buffer_overruns(struct ring_buffer *buffer) | |
3330 | { | |
3331 | struct ring_buffer_per_cpu *cpu_buffer; | |
3332 | unsigned long overruns = 0; | |
3333 | int cpu; | |
3334 | ||
3335 | /* if you care about this being correct, lock the buffer */ | |
3336 | for_each_buffer_cpu(buffer, cpu) { | |
3337 | cpu_buffer = buffer->buffers[cpu]; | |
77ae365e | 3338 | overruns += local_read(&cpu_buffer->overrun); |
7a8e76a3 SR |
3339 | } |
3340 | ||
3341 | return overruns; | |
3342 | } | |
c4f50183 | 3343 | EXPORT_SYMBOL_GPL(ring_buffer_overruns); |
7a8e76a3 | 3344 | |
642edba5 | 3345 | static void rb_iter_reset(struct ring_buffer_iter *iter) |
7a8e76a3 SR |
3346 | { |
3347 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
3348 | ||
d769041f SR |
3349 | /* Iterator usage is expected to have record disabled */ |
3350 | if (list_empty(&cpu_buffer->reader_page->list)) { | |
77ae365e SR |
3351 | iter->head_page = rb_set_head_page(cpu_buffer); |
3352 | if (unlikely(!iter->head_page)) | |
3353 | return; | |
3354 | iter->head = iter->head_page->read; | |
d769041f SR |
3355 | } else { |
3356 | iter->head_page = cpu_buffer->reader_page; | |
6f807acd | 3357 | iter->head = cpu_buffer->reader_page->read; |
d769041f SR |
3358 | } |
3359 | if (iter->head) | |
3360 | iter->read_stamp = cpu_buffer->read_stamp; | |
3361 | else | |
abc9b56d | 3362 | iter->read_stamp = iter->head_page->page->time_stamp; |
492a74f4 SR |
3363 | iter->cache_reader_page = cpu_buffer->reader_page; |
3364 | iter->cache_read = cpu_buffer->read; | |
642edba5 | 3365 | } |
f83c9d0f | 3366 | |
642edba5 SR |
3367 | /** |
3368 | * ring_buffer_iter_reset - reset an iterator | |
3369 | * @iter: The iterator to reset | |
3370 | * | |
3371 | * Resets the iterator, so that it will start from the beginning | |
3372 | * again. | |
3373 | */ | |
3374 | void ring_buffer_iter_reset(struct ring_buffer_iter *iter) | |
3375 | { | |
554f786e | 3376 | struct ring_buffer_per_cpu *cpu_buffer; |
642edba5 SR |
3377 | unsigned long flags; |
3378 | ||
554f786e SR |
3379 | if (!iter) |
3380 | return; | |
3381 | ||
3382 | cpu_buffer = iter->cpu_buffer; | |
3383 | ||
5389f6fa | 3384 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
642edba5 | 3385 | rb_iter_reset(iter); |
5389f6fa | 3386 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
7a8e76a3 | 3387 | } |
c4f50183 | 3388 | EXPORT_SYMBOL_GPL(ring_buffer_iter_reset); |
7a8e76a3 SR |
3389 | |
3390 | /** | |
3391 | * ring_buffer_iter_empty - check if an iterator has no more to read | |
3392 | * @iter: The iterator to check | |
3393 | */ | |
3394 | int ring_buffer_iter_empty(struct ring_buffer_iter *iter) | |
3395 | { | |
3396 | struct ring_buffer_per_cpu *cpu_buffer; | |
3397 | ||
3398 | cpu_buffer = iter->cpu_buffer; | |
3399 | ||
bf41a158 SR |
3400 | return iter->head_page == cpu_buffer->commit_page && |
3401 | iter->head == rb_commit_index(cpu_buffer); | |
7a8e76a3 | 3402 | } |
c4f50183 | 3403 | EXPORT_SYMBOL_GPL(ring_buffer_iter_empty); |
7a8e76a3 SR |
3404 | |
3405 | static void | |
3406 | rb_update_read_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
3407 | struct ring_buffer_event *event) | |
3408 | { | |
3409 | u64 delta; | |
3410 | ||
334d4169 | 3411 | switch (event->type_len) { |
7a8e76a3 SR |
3412 | case RINGBUF_TYPE_PADDING: |
3413 | return; | |
3414 | ||
3415 | case RINGBUF_TYPE_TIME_EXTEND: | |
3416 | delta = event->array[0]; | |
3417 | delta <<= TS_SHIFT; | |
3418 | delta += event->time_delta; | |
3419 | cpu_buffer->read_stamp += delta; | |
3420 | return; | |
3421 | ||
3422 | case RINGBUF_TYPE_TIME_STAMP: | |
3423 | /* FIXME: not implemented */ | |
3424 | return; | |
3425 | ||
3426 | case RINGBUF_TYPE_DATA: | |
3427 | cpu_buffer->read_stamp += event->time_delta; | |
3428 | return; | |
3429 | ||
3430 | default: | |
3431 | BUG(); | |
3432 | } | |
3433 | return; | |
3434 | } | |
3435 | ||
3436 | static void | |
3437 | rb_update_iter_read_stamp(struct ring_buffer_iter *iter, | |
3438 | struct ring_buffer_event *event) | |
3439 | { | |
3440 | u64 delta; | |
3441 | ||
334d4169 | 3442 | switch (event->type_len) { |
7a8e76a3 SR |
3443 | case RINGBUF_TYPE_PADDING: |
3444 | return; | |
3445 | ||
3446 | case RINGBUF_TYPE_TIME_EXTEND: | |
3447 | delta = event->array[0]; | |
3448 | delta <<= TS_SHIFT; | |
3449 | delta += event->time_delta; | |
3450 | iter->read_stamp += delta; | |
3451 | return; | |
3452 | ||
3453 | case RINGBUF_TYPE_TIME_STAMP: | |
3454 | /* FIXME: not implemented */ | |
3455 | return; | |
3456 | ||
3457 | case RINGBUF_TYPE_DATA: | |
3458 | iter->read_stamp += event->time_delta; | |
3459 | return; | |
3460 | ||
3461 | default: | |
3462 | BUG(); | |
3463 | } | |
3464 | return; | |
3465 | } | |
3466 | ||
d769041f SR |
3467 | static struct buffer_page * |
3468 | rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) | |
7a8e76a3 | 3469 | { |
d769041f | 3470 | struct buffer_page *reader = NULL; |
66a8cb95 | 3471 | unsigned long overwrite; |
d769041f | 3472 | unsigned long flags; |
818e3dd3 | 3473 | int nr_loops = 0; |
77ae365e | 3474 | int ret; |
d769041f | 3475 | |
3e03fb7f | 3476 | local_irq_save(flags); |
0199c4e6 | 3477 | arch_spin_lock(&cpu_buffer->lock); |
d769041f SR |
3478 | |
3479 | again: | |
818e3dd3 SR |
3480 | /* |
3481 | * This should normally only loop twice. But because the | |
3482 | * start of the reader inserts an empty page, it causes | |
3483 | * a case where we will loop three times. There should be no | |
3484 | * reason to loop four times (that I know of). | |
3485 | */ | |
3e89c7bb | 3486 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 3)) { |
818e3dd3 SR |
3487 | reader = NULL; |
3488 | goto out; | |
3489 | } | |
3490 | ||
d769041f SR |
3491 | reader = cpu_buffer->reader_page; |
3492 | ||
3493 | /* If there's more to read, return this page */ | |
bf41a158 | 3494 | if (cpu_buffer->reader_page->read < rb_page_size(reader)) |
d769041f SR |
3495 | goto out; |
3496 | ||
3497 | /* Never should we have an index greater than the size */ | |
3e89c7bb SR |
3498 | if (RB_WARN_ON(cpu_buffer, |
3499 | cpu_buffer->reader_page->read > rb_page_size(reader))) | |
3500 | goto out; | |
d769041f SR |
3501 | |
3502 | /* check if we caught up to the tail */ | |
3503 | reader = NULL; | |
bf41a158 | 3504 | if (cpu_buffer->commit_page == cpu_buffer->reader_page) |
d769041f | 3505 | goto out; |
7a8e76a3 | 3506 | |
a5fb8331 SR |
3507 | /* Don't bother swapping if the ring buffer is empty */ |
3508 | if (rb_num_of_entries(cpu_buffer) == 0) | |
3509 | goto out; | |
3510 | ||
7a8e76a3 | 3511 | /* |
d769041f | 3512 | * Reset the reader page to size zero. |
7a8e76a3 | 3513 | */ |
77ae365e SR |
3514 | local_set(&cpu_buffer->reader_page->write, 0); |
3515 | local_set(&cpu_buffer->reader_page->entries, 0); | |
3516 | local_set(&cpu_buffer->reader_page->page->commit, 0); | |
ff0ff84a | 3517 | cpu_buffer->reader_page->real_end = 0; |
7a8e76a3 | 3518 | |
77ae365e SR |
3519 | spin: |
3520 | /* | |
3521 | * Splice the empty reader page into the list around the head. | |
3522 | */ | |
3523 | reader = rb_set_head_page(cpu_buffer); | |
54f7be5b SR |
3524 | if (!reader) |
3525 | goto out; | |
0e1ff5d7 | 3526 | cpu_buffer->reader_page->list.next = rb_list_head(reader->list.next); |
d769041f | 3527 | cpu_buffer->reader_page->list.prev = reader->list.prev; |
bf41a158 | 3528 | |
3adc54fa SR |
3529 | /* |
3530 | * cpu_buffer->pages just needs to point to the buffer, it | |
3531 | * has no specific buffer page to point to. Lets move it out | |
25985edc | 3532 | * of our way so we don't accidentally swap it. |
3adc54fa SR |
3533 | */ |
3534 | cpu_buffer->pages = reader->list.prev; | |
3535 | ||
77ae365e SR |
3536 | /* The reader page will be pointing to the new head */ |
3537 | rb_set_list_to_head(cpu_buffer, &cpu_buffer->reader_page->list); | |
7a8e76a3 | 3538 | |
66a8cb95 SR |
3539 | /* |
3540 | * We want to make sure we read the overruns after we set up our | |
3541 | * pointers to the next object. The writer side does a | |
3542 | * cmpxchg to cross pages which acts as the mb on the writer | |
3543 | * side. Note, the reader will constantly fail the swap | |
3544 | * while the writer is updating the pointers, so this | |
3545 | * guarantees that the overwrite recorded here is the one we | |
3546 | * want to compare with the last_overrun. | |
3547 | */ | |
3548 | smp_mb(); | |
3549 | overwrite = local_read(&(cpu_buffer->overrun)); | |
3550 | ||
77ae365e SR |
3551 | /* |
3552 | * Here's the tricky part. | |
3553 | * | |
3554 | * We need to move the pointer past the header page. | |
3555 | * But we can only do that if a writer is not currently | |
3556 | * moving it. The page before the header page has the | |
3557 | * flag bit '1' set if it is pointing to the page we want. | |
3558 | * but if the writer is in the process of moving it | |
3559 | * than it will be '2' or already moved '0'. | |
3560 | */ | |
3561 | ||
3562 | ret = rb_head_page_replace(reader, cpu_buffer->reader_page); | |
7a8e76a3 SR |
3563 | |
3564 | /* | |
77ae365e | 3565 | * If we did not convert it, then we must try again. |
7a8e76a3 | 3566 | */ |
77ae365e SR |
3567 | if (!ret) |
3568 | goto spin; | |
7a8e76a3 | 3569 | |
77ae365e SR |
3570 | /* |
3571 | * Yeah! We succeeded in replacing the page. | |
3572 | * | |
3573 | * Now make the new head point back to the reader page. | |
3574 | */ | |
5ded3dc6 | 3575 | rb_list_head(reader->list.next)->prev = &cpu_buffer->reader_page->list; |
77ae365e | 3576 | rb_inc_page(cpu_buffer, &cpu_buffer->head_page); |
d769041f SR |
3577 | |
3578 | /* Finally update the reader page to the new head */ | |
3579 | cpu_buffer->reader_page = reader; | |
3580 | rb_reset_reader_page(cpu_buffer); | |
3581 | ||
66a8cb95 SR |
3582 | if (overwrite != cpu_buffer->last_overrun) { |
3583 | cpu_buffer->lost_events = overwrite - cpu_buffer->last_overrun; | |
3584 | cpu_buffer->last_overrun = overwrite; | |
3585 | } | |
3586 | ||
d769041f SR |
3587 | goto again; |
3588 | ||
3589 | out: | |
0199c4e6 | 3590 | arch_spin_unlock(&cpu_buffer->lock); |
3e03fb7f | 3591 | local_irq_restore(flags); |
d769041f SR |
3592 | |
3593 | return reader; | |
3594 | } | |
3595 | ||
3596 | static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer) | |
3597 | { | |
3598 | struct ring_buffer_event *event; | |
3599 | struct buffer_page *reader; | |
3600 | unsigned length; | |
3601 | ||
3602 | reader = rb_get_reader_page(cpu_buffer); | |
7a8e76a3 | 3603 | |
d769041f | 3604 | /* This function should not be called when buffer is empty */ |
3e89c7bb SR |
3605 | if (RB_WARN_ON(cpu_buffer, !reader)) |
3606 | return; | |
7a8e76a3 | 3607 | |
d769041f SR |
3608 | event = rb_reader_event(cpu_buffer); |
3609 | ||
a1863c21 | 3610 | if (event->type_len <= RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
e4906eff | 3611 | cpu_buffer->read++; |
d769041f SR |
3612 | |
3613 | rb_update_read_stamp(cpu_buffer, event); | |
3614 | ||
3615 | length = rb_event_length(event); | |
6f807acd | 3616 | cpu_buffer->reader_page->read += length; |
7a8e76a3 SR |
3617 | } |
3618 | ||
3619 | static void rb_advance_iter(struct ring_buffer_iter *iter) | |
3620 | { | |
7a8e76a3 SR |
3621 | struct ring_buffer_per_cpu *cpu_buffer; |
3622 | struct ring_buffer_event *event; | |
3623 | unsigned length; | |
3624 | ||
3625 | cpu_buffer = iter->cpu_buffer; | |
7a8e76a3 SR |
3626 | |
3627 | /* | |
3628 | * Check if we are at the end of the buffer. | |
3629 | */ | |
bf41a158 | 3630 | if (iter->head >= rb_page_size(iter->head_page)) { |
ea05b57c SR |
3631 | /* discarded commits can make the page empty */ |
3632 | if (iter->head_page == cpu_buffer->commit_page) | |
3e89c7bb | 3633 | return; |
d769041f | 3634 | rb_inc_iter(iter); |
7a8e76a3 SR |
3635 | return; |
3636 | } | |
3637 | ||
3638 | event = rb_iter_head_event(iter); | |
3639 | ||
3640 | length = rb_event_length(event); | |
3641 | ||
3642 | /* | |
3643 | * This should not be called to advance the header if we are | |
3644 | * at the tail of the buffer. | |
3645 | */ | |
3e89c7bb | 3646 | if (RB_WARN_ON(cpu_buffer, |
f536aafc | 3647 | (iter->head_page == cpu_buffer->commit_page) && |
3e89c7bb SR |
3648 | (iter->head + length > rb_commit_index(cpu_buffer)))) |
3649 | return; | |
7a8e76a3 SR |
3650 | |
3651 | rb_update_iter_read_stamp(iter, event); | |
3652 | ||
3653 | iter->head += length; | |
3654 | ||
3655 | /* check for end of page padding */ | |
bf41a158 SR |
3656 | if ((iter->head >= rb_page_size(iter->head_page)) && |
3657 | (iter->head_page != cpu_buffer->commit_page)) | |
771e0384 | 3658 | rb_inc_iter(iter); |
7a8e76a3 SR |
3659 | } |
3660 | ||
66a8cb95 SR |
3661 | static int rb_lost_events(struct ring_buffer_per_cpu *cpu_buffer) |
3662 | { | |
3663 | return cpu_buffer->lost_events; | |
3664 | } | |
3665 | ||
f83c9d0f | 3666 | static struct ring_buffer_event * |
66a8cb95 SR |
3667 | rb_buffer_peek(struct ring_buffer_per_cpu *cpu_buffer, u64 *ts, |
3668 | unsigned long *lost_events) | |
7a8e76a3 | 3669 | { |
7a8e76a3 | 3670 | struct ring_buffer_event *event; |
d769041f | 3671 | struct buffer_page *reader; |
818e3dd3 | 3672 | int nr_loops = 0; |
7a8e76a3 | 3673 | |
7a8e76a3 | 3674 | again: |
818e3dd3 | 3675 | /* |
69d1b839 SR |
3676 | * We repeat when a time extend is encountered. |
3677 | * Since the time extend is always attached to a data event, | |
3678 | * we should never loop more than once. | |
3679 | * (We never hit the following condition more than twice). | |
818e3dd3 | 3680 | */ |
69d1b839 | 3681 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 2)) |
818e3dd3 | 3682 | return NULL; |
818e3dd3 | 3683 | |
d769041f SR |
3684 | reader = rb_get_reader_page(cpu_buffer); |
3685 | if (!reader) | |
7a8e76a3 SR |
3686 | return NULL; |
3687 | ||
d769041f | 3688 | event = rb_reader_event(cpu_buffer); |
7a8e76a3 | 3689 | |
334d4169 | 3690 | switch (event->type_len) { |
7a8e76a3 | 3691 | case RINGBUF_TYPE_PADDING: |
2d622719 TZ |
3692 | if (rb_null_event(event)) |
3693 | RB_WARN_ON(cpu_buffer, 1); | |
3694 | /* | |
3695 | * Because the writer could be discarding every | |
3696 | * event it creates (which would probably be bad) | |
3697 | * if we were to go back to "again" then we may never | |
3698 | * catch up, and will trigger the warn on, or lock | |
3699 | * the box. Return the padding, and we will release | |
3700 | * the current locks, and try again. | |
3701 | */ | |
2d622719 | 3702 | return event; |
7a8e76a3 SR |
3703 | |
3704 | case RINGBUF_TYPE_TIME_EXTEND: | |
3705 | /* Internal data, OK to advance */ | |
d769041f | 3706 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
3707 | goto again; |
3708 | ||
3709 | case RINGBUF_TYPE_TIME_STAMP: | |
3710 | /* FIXME: not implemented */ | |
d769041f | 3711 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
3712 | goto again; |
3713 | ||
3714 | case RINGBUF_TYPE_DATA: | |
3715 | if (ts) { | |
3716 | *ts = cpu_buffer->read_stamp + event->time_delta; | |
d8eeb2d3 | 3717 | ring_buffer_normalize_time_stamp(cpu_buffer->buffer, |
37886f6a | 3718 | cpu_buffer->cpu, ts); |
7a8e76a3 | 3719 | } |
66a8cb95 SR |
3720 | if (lost_events) |
3721 | *lost_events = rb_lost_events(cpu_buffer); | |
7a8e76a3 SR |
3722 | return event; |
3723 | ||
3724 | default: | |
3725 | BUG(); | |
3726 | } | |
3727 | ||
3728 | return NULL; | |
3729 | } | |
c4f50183 | 3730 | EXPORT_SYMBOL_GPL(ring_buffer_peek); |
7a8e76a3 | 3731 | |
f83c9d0f SR |
3732 | static struct ring_buffer_event * |
3733 | rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) | |
7a8e76a3 SR |
3734 | { |
3735 | struct ring_buffer *buffer; | |
3736 | struct ring_buffer_per_cpu *cpu_buffer; | |
3737 | struct ring_buffer_event *event; | |
818e3dd3 | 3738 | int nr_loops = 0; |
7a8e76a3 | 3739 | |
7a8e76a3 SR |
3740 | cpu_buffer = iter->cpu_buffer; |
3741 | buffer = cpu_buffer->buffer; | |
3742 | ||
492a74f4 SR |
3743 | /* |
3744 | * Check if someone performed a consuming read to | |
3745 | * the buffer. A consuming read invalidates the iterator | |
3746 | * and we need to reset the iterator in this case. | |
3747 | */ | |
3748 | if (unlikely(iter->cache_read != cpu_buffer->read || | |
3749 | iter->cache_reader_page != cpu_buffer->reader_page)) | |
3750 | rb_iter_reset(iter); | |
3751 | ||
7a8e76a3 | 3752 | again: |
3c05d748 SR |
3753 | if (ring_buffer_iter_empty(iter)) |
3754 | return NULL; | |
3755 | ||
818e3dd3 | 3756 | /* |
69d1b839 SR |
3757 | * We repeat when a time extend is encountered. |
3758 | * Since the time extend is always attached to a data event, | |
3759 | * we should never loop more than once. | |
3760 | * (We never hit the following condition more than twice). | |
818e3dd3 | 3761 | */ |
69d1b839 | 3762 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 2)) |
818e3dd3 | 3763 | return NULL; |
818e3dd3 | 3764 | |
7a8e76a3 SR |
3765 | if (rb_per_cpu_empty(cpu_buffer)) |
3766 | return NULL; | |
3767 | ||
3c05d748 SR |
3768 | if (iter->head >= local_read(&iter->head_page->page->commit)) { |
3769 | rb_inc_iter(iter); | |
3770 | goto again; | |
3771 | } | |
3772 | ||
7a8e76a3 SR |
3773 | event = rb_iter_head_event(iter); |
3774 | ||
334d4169 | 3775 | switch (event->type_len) { |
7a8e76a3 | 3776 | case RINGBUF_TYPE_PADDING: |
2d622719 TZ |
3777 | if (rb_null_event(event)) { |
3778 | rb_inc_iter(iter); | |
3779 | goto again; | |
3780 | } | |
3781 | rb_advance_iter(iter); | |
3782 | return event; | |
7a8e76a3 SR |
3783 | |
3784 | case RINGBUF_TYPE_TIME_EXTEND: | |
3785 | /* Internal data, OK to advance */ | |
3786 | rb_advance_iter(iter); | |
3787 | goto again; | |
3788 | ||
3789 | case RINGBUF_TYPE_TIME_STAMP: | |
3790 | /* FIXME: not implemented */ | |
3791 | rb_advance_iter(iter); | |
3792 | goto again; | |
3793 | ||
3794 | case RINGBUF_TYPE_DATA: | |
3795 | if (ts) { | |
3796 | *ts = iter->read_stamp + event->time_delta; | |
37886f6a SR |
3797 | ring_buffer_normalize_time_stamp(buffer, |
3798 | cpu_buffer->cpu, ts); | |
7a8e76a3 SR |
3799 | } |
3800 | return event; | |
3801 | ||
3802 | default: | |
3803 | BUG(); | |
3804 | } | |
3805 | ||
3806 | return NULL; | |
3807 | } | |
c4f50183 | 3808 | EXPORT_SYMBOL_GPL(ring_buffer_iter_peek); |
7a8e76a3 | 3809 | |
8d707e8e SR |
3810 | static inline int rb_ok_to_lock(void) |
3811 | { | |
3812 | /* | |
3813 | * If an NMI die dumps out the content of the ring buffer | |
3814 | * do not grab locks. We also permanently disable the ring | |
3815 | * buffer too. A one time deal is all you get from reading | |
3816 | * the ring buffer from an NMI. | |
3817 | */ | |
464e85eb | 3818 | if (likely(!in_nmi())) |
8d707e8e SR |
3819 | return 1; |
3820 | ||
3821 | tracing_off_permanent(); | |
3822 | return 0; | |
3823 | } | |
3824 | ||
f83c9d0f SR |
3825 | /** |
3826 | * ring_buffer_peek - peek at the next event to be read | |
3827 | * @buffer: The ring buffer to read | |
3828 | * @cpu: The cpu to peak at | |
3829 | * @ts: The timestamp counter of this event. | |
66a8cb95 | 3830 | * @lost_events: a variable to store if events were lost (may be NULL) |
f83c9d0f SR |
3831 | * |
3832 | * This will return the event that will be read next, but does | |
3833 | * not consume the data. | |
3834 | */ | |
3835 | struct ring_buffer_event * | |
66a8cb95 SR |
3836 | ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts, |
3837 | unsigned long *lost_events) | |
f83c9d0f SR |
3838 | { |
3839 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
8aabee57 | 3840 | struct ring_buffer_event *event; |
f83c9d0f | 3841 | unsigned long flags; |
8d707e8e | 3842 | int dolock; |
f83c9d0f | 3843 | |
554f786e | 3844 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 3845 | return NULL; |
554f786e | 3846 | |
8d707e8e | 3847 | dolock = rb_ok_to_lock(); |
2d622719 | 3848 | again: |
8d707e8e SR |
3849 | local_irq_save(flags); |
3850 | if (dolock) | |
5389f6fa | 3851 | raw_spin_lock(&cpu_buffer->reader_lock); |
66a8cb95 | 3852 | event = rb_buffer_peek(cpu_buffer, ts, lost_events); |
469535a5 RR |
3853 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
3854 | rb_advance_reader(cpu_buffer); | |
8d707e8e | 3855 | if (dolock) |
5389f6fa | 3856 | raw_spin_unlock(&cpu_buffer->reader_lock); |
8d707e8e | 3857 | local_irq_restore(flags); |
f83c9d0f | 3858 | |
1b959e18 | 3859 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
2d622719 | 3860 | goto again; |
2d622719 | 3861 | |
f83c9d0f SR |
3862 | return event; |
3863 | } | |
3864 | ||
3865 | /** | |
3866 | * ring_buffer_iter_peek - peek at the next event to be read | |
3867 | * @iter: The ring buffer iterator | |
3868 | * @ts: The timestamp counter of this event. | |
3869 | * | |
3870 | * This will return the event that will be read next, but does | |
3871 | * not increment the iterator. | |
3872 | */ | |
3873 | struct ring_buffer_event * | |
3874 | ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) | |
3875 | { | |
3876 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
3877 | struct ring_buffer_event *event; | |
3878 | unsigned long flags; | |
3879 | ||
2d622719 | 3880 | again: |
5389f6fa | 3881 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
f83c9d0f | 3882 | event = rb_iter_peek(iter, ts); |
5389f6fa | 3883 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
f83c9d0f | 3884 | |
1b959e18 | 3885 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
2d622719 | 3886 | goto again; |
2d622719 | 3887 | |
f83c9d0f SR |
3888 | return event; |
3889 | } | |
3890 | ||
7a8e76a3 SR |
3891 | /** |
3892 | * ring_buffer_consume - return an event and consume it | |
3893 | * @buffer: The ring buffer to get the next event from | |
66a8cb95 SR |
3894 | * @cpu: the cpu to read the buffer from |
3895 | * @ts: a variable to store the timestamp (may be NULL) | |
3896 | * @lost_events: a variable to store if events were lost (may be NULL) | |
7a8e76a3 SR |
3897 | * |
3898 | * Returns the next event in the ring buffer, and that event is consumed. | |
3899 | * Meaning, that sequential reads will keep returning a different event, | |
3900 | * and eventually empty the ring buffer if the producer is slower. | |
3901 | */ | |
3902 | struct ring_buffer_event * | |
66a8cb95 SR |
3903 | ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts, |
3904 | unsigned long *lost_events) | |
7a8e76a3 | 3905 | { |
554f786e SR |
3906 | struct ring_buffer_per_cpu *cpu_buffer; |
3907 | struct ring_buffer_event *event = NULL; | |
f83c9d0f | 3908 | unsigned long flags; |
8d707e8e SR |
3909 | int dolock; |
3910 | ||
3911 | dolock = rb_ok_to_lock(); | |
7a8e76a3 | 3912 | |
2d622719 | 3913 | again: |
554f786e SR |
3914 | /* might be called in atomic */ |
3915 | preempt_disable(); | |
3916 | ||
9e01c1b7 | 3917 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
554f786e | 3918 | goto out; |
7a8e76a3 | 3919 | |
554f786e | 3920 | cpu_buffer = buffer->buffers[cpu]; |
8d707e8e SR |
3921 | local_irq_save(flags); |
3922 | if (dolock) | |
5389f6fa | 3923 | raw_spin_lock(&cpu_buffer->reader_lock); |
f83c9d0f | 3924 | |
66a8cb95 SR |
3925 | event = rb_buffer_peek(cpu_buffer, ts, lost_events); |
3926 | if (event) { | |
3927 | cpu_buffer->lost_events = 0; | |
469535a5 | 3928 | rb_advance_reader(cpu_buffer); |
66a8cb95 | 3929 | } |
7a8e76a3 | 3930 | |
8d707e8e | 3931 | if (dolock) |
5389f6fa | 3932 | raw_spin_unlock(&cpu_buffer->reader_lock); |
8d707e8e | 3933 | local_irq_restore(flags); |
f83c9d0f | 3934 | |
554f786e SR |
3935 | out: |
3936 | preempt_enable(); | |
3937 | ||
1b959e18 | 3938 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
2d622719 | 3939 | goto again; |
2d622719 | 3940 | |
7a8e76a3 SR |
3941 | return event; |
3942 | } | |
c4f50183 | 3943 | EXPORT_SYMBOL_GPL(ring_buffer_consume); |
7a8e76a3 SR |
3944 | |
3945 | /** | |
72c9ddfd | 3946 | * ring_buffer_read_prepare - Prepare for a non consuming read of the buffer |
7a8e76a3 SR |
3947 | * @buffer: The ring buffer to read from |
3948 | * @cpu: The cpu buffer to iterate over | |
3949 | * | |
72c9ddfd DM |
3950 | * This performs the initial preparations necessary to iterate |
3951 | * through the buffer. Memory is allocated, buffer recording | |
3952 | * is disabled, and the iterator pointer is returned to the caller. | |
7a8e76a3 | 3953 | * |
72c9ddfd DM |
3954 | * Disabling buffer recordng prevents the reading from being |
3955 | * corrupted. This is not a consuming read, so a producer is not | |
3956 | * expected. | |
3957 | * | |
3958 | * After a sequence of ring_buffer_read_prepare calls, the user is | |
3959 | * expected to make at least one call to ring_buffer_prepare_sync. | |
3960 | * Afterwards, ring_buffer_read_start is invoked to get things going | |
3961 | * for real. | |
3962 | * | |
3963 | * This overall must be paired with ring_buffer_finish. | |
7a8e76a3 SR |
3964 | */ |
3965 | struct ring_buffer_iter * | |
72c9ddfd | 3966 | ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu) |
7a8e76a3 SR |
3967 | { |
3968 | struct ring_buffer_per_cpu *cpu_buffer; | |
8aabee57 | 3969 | struct ring_buffer_iter *iter; |
7a8e76a3 | 3970 | |
9e01c1b7 | 3971 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 3972 | return NULL; |
7a8e76a3 SR |
3973 | |
3974 | iter = kmalloc(sizeof(*iter), GFP_KERNEL); | |
3975 | if (!iter) | |
8aabee57 | 3976 | return NULL; |
7a8e76a3 SR |
3977 | |
3978 | cpu_buffer = buffer->buffers[cpu]; | |
3979 | ||
3980 | iter->cpu_buffer = cpu_buffer; | |
3981 | ||
83f40318 | 3982 | atomic_inc(&buffer->resize_disabled); |
7a8e76a3 | 3983 | atomic_inc(&cpu_buffer->record_disabled); |
72c9ddfd DM |
3984 | |
3985 | return iter; | |
3986 | } | |
3987 | EXPORT_SYMBOL_GPL(ring_buffer_read_prepare); | |
3988 | ||
3989 | /** | |
3990 | * ring_buffer_read_prepare_sync - Synchronize a set of prepare calls | |
3991 | * | |
3992 | * All previously invoked ring_buffer_read_prepare calls to prepare | |
3993 | * iterators will be synchronized. Afterwards, read_buffer_read_start | |
3994 | * calls on those iterators are allowed. | |
3995 | */ | |
3996 | void | |
3997 | ring_buffer_read_prepare_sync(void) | |
3998 | { | |
7a8e76a3 | 3999 | synchronize_sched(); |
72c9ddfd DM |
4000 | } |
4001 | EXPORT_SYMBOL_GPL(ring_buffer_read_prepare_sync); | |
4002 | ||
4003 | /** | |
4004 | * ring_buffer_read_start - start a non consuming read of the buffer | |
4005 | * @iter: The iterator returned by ring_buffer_read_prepare | |
4006 | * | |
4007 | * This finalizes the startup of an iteration through the buffer. | |
4008 | * The iterator comes from a call to ring_buffer_read_prepare and | |
4009 | * an intervening ring_buffer_read_prepare_sync must have been | |
4010 | * performed. | |
4011 | * | |
4012 | * Must be paired with ring_buffer_finish. | |
4013 | */ | |
4014 | void | |
4015 | ring_buffer_read_start(struct ring_buffer_iter *iter) | |
4016 | { | |
4017 | struct ring_buffer_per_cpu *cpu_buffer; | |
4018 | unsigned long flags; | |
4019 | ||
4020 | if (!iter) | |
4021 | return; | |
4022 | ||
4023 | cpu_buffer = iter->cpu_buffer; | |
7a8e76a3 | 4024 | |
5389f6fa | 4025 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
0199c4e6 | 4026 | arch_spin_lock(&cpu_buffer->lock); |
642edba5 | 4027 | rb_iter_reset(iter); |
0199c4e6 | 4028 | arch_spin_unlock(&cpu_buffer->lock); |
5389f6fa | 4029 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
7a8e76a3 | 4030 | } |
c4f50183 | 4031 | EXPORT_SYMBOL_GPL(ring_buffer_read_start); |
7a8e76a3 SR |
4032 | |
4033 | /** | |
4034 | * ring_buffer_finish - finish reading the iterator of the buffer | |
4035 | * @iter: The iterator retrieved by ring_buffer_start | |
4036 | * | |
4037 | * This re-enables the recording to the buffer, and frees the | |
4038 | * iterator. | |
4039 | */ | |
4040 | void | |
4041 | ring_buffer_read_finish(struct ring_buffer_iter *iter) | |
4042 | { | |
4043 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
9366c1ba | 4044 | unsigned long flags; |
7a8e76a3 | 4045 | |
659f451f SR |
4046 | /* |
4047 | * Ring buffer is disabled from recording, here's a good place | |
9366c1ba SR |
4048 | * to check the integrity of the ring buffer. |
4049 | * Must prevent readers from trying to read, as the check | |
4050 | * clears the HEAD page and readers require it. | |
659f451f | 4051 | */ |
9366c1ba | 4052 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
659f451f | 4053 | rb_check_pages(cpu_buffer); |
9366c1ba | 4054 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
659f451f | 4055 | |
7a8e76a3 | 4056 | atomic_dec(&cpu_buffer->record_disabled); |
83f40318 | 4057 | atomic_dec(&cpu_buffer->buffer->resize_disabled); |
7a8e76a3 SR |
4058 | kfree(iter); |
4059 | } | |
c4f50183 | 4060 | EXPORT_SYMBOL_GPL(ring_buffer_read_finish); |
7a8e76a3 SR |
4061 | |
4062 | /** | |
4063 | * ring_buffer_read - read the next item in the ring buffer by the iterator | |
4064 | * @iter: The ring buffer iterator | |
4065 | * @ts: The time stamp of the event read. | |
4066 | * | |
4067 | * This reads the next event in the ring buffer and increments the iterator. | |
4068 | */ | |
4069 | struct ring_buffer_event * | |
4070 | ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) | |
4071 | { | |
4072 | struct ring_buffer_event *event; | |
f83c9d0f SR |
4073 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
4074 | unsigned long flags; | |
7a8e76a3 | 4075 | |
5389f6fa | 4076 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
7e9391cf | 4077 | again: |
f83c9d0f | 4078 | event = rb_iter_peek(iter, ts); |
7a8e76a3 | 4079 | if (!event) |
f83c9d0f | 4080 | goto out; |
7a8e76a3 | 4081 | |
7e9391cf SR |
4082 | if (event->type_len == RINGBUF_TYPE_PADDING) |
4083 | goto again; | |
4084 | ||
7a8e76a3 | 4085 | rb_advance_iter(iter); |
f83c9d0f | 4086 | out: |
5389f6fa | 4087 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
7a8e76a3 SR |
4088 | |
4089 | return event; | |
4090 | } | |
c4f50183 | 4091 | EXPORT_SYMBOL_GPL(ring_buffer_read); |
7a8e76a3 SR |
4092 | |
4093 | /** | |
4094 | * ring_buffer_size - return the size of the ring buffer (in bytes) | |
4095 | * @buffer: The ring buffer. | |
4096 | */ | |
438ced17 | 4097 | unsigned long ring_buffer_size(struct ring_buffer *buffer, int cpu) |
7a8e76a3 | 4098 | { |
438ced17 VN |
4099 | /* |
4100 | * Earlier, this method returned | |
4101 | * BUF_PAGE_SIZE * buffer->nr_pages | |
4102 | * Since the nr_pages field is now removed, we have converted this to | |
4103 | * return the per cpu buffer value. | |
4104 | */ | |
4105 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
4106 | return 0; | |
4107 | ||
4108 | return BUF_PAGE_SIZE * buffer->buffers[cpu]->nr_pages; | |
7a8e76a3 | 4109 | } |
c4f50183 | 4110 | EXPORT_SYMBOL_GPL(ring_buffer_size); |
7a8e76a3 SR |
4111 | |
4112 | static void | |
4113 | rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) | |
4114 | { | |
77ae365e SR |
4115 | rb_head_page_deactivate(cpu_buffer); |
4116 | ||
7a8e76a3 | 4117 | cpu_buffer->head_page |
3adc54fa | 4118 | = list_entry(cpu_buffer->pages, struct buffer_page, list); |
bf41a158 | 4119 | local_set(&cpu_buffer->head_page->write, 0); |
778c55d4 | 4120 | local_set(&cpu_buffer->head_page->entries, 0); |
abc9b56d | 4121 | local_set(&cpu_buffer->head_page->page->commit, 0); |
d769041f | 4122 | |
6f807acd | 4123 | cpu_buffer->head_page->read = 0; |
bf41a158 SR |
4124 | |
4125 | cpu_buffer->tail_page = cpu_buffer->head_page; | |
4126 | cpu_buffer->commit_page = cpu_buffer->head_page; | |
4127 | ||
4128 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); | |
5040b4b7 | 4129 | INIT_LIST_HEAD(&cpu_buffer->new_pages); |
bf41a158 | 4130 | local_set(&cpu_buffer->reader_page->write, 0); |
778c55d4 | 4131 | local_set(&cpu_buffer->reader_page->entries, 0); |
abc9b56d | 4132 | local_set(&cpu_buffer->reader_page->page->commit, 0); |
6f807acd | 4133 | cpu_buffer->reader_page->read = 0; |
7a8e76a3 | 4134 | |
c64e148a | 4135 | local_set(&cpu_buffer->entries_bytes, 0); |
77ae365e | 4136 | local_set(&cpu_buffer->overrun, 0); |
884bfe89 SP |
4137 | local_set(&cpu_buffer->commit_overrun, 0); |
4138 | local_set(&cpu_buffer->dropped_events, 0); | |
e4906eff | 4139 | local_set(&cpu_buffer->entries, 0); |
fa743953 SR |
4140 | local_set(&cpu_buffer->committing, 0); |
4141 | local_set(&cpu_buffer->commits, 0); | |
77ae365e | 4142 | cpu_buffer->read = 0; |
c64e148a | 4143 | cpu_buffer->read_bytes = 0; |
69507c06 SR |
4144 | |
4145 | cpu_buffer->write_stamp = 0; | |
4146 | cpu_buffer->read_stamp = 0; | |
77ae365e | 4147 | |
66a8cb95 SR |
4148 | cpu_buffer->lost_events = 0; |
4149 | cpu_buffer->last_overrun = 0; | |
4150 | ||
77ae365e | 4151 | rb_head_page_activate(cpu_buffer); |
7a8e76a3 SR |
4152 | } |
4153 | ||
4154 | /** | |
4155 | * ring_buffer_reset_cpu - reset a ring buffer per CPU buffer | |
4156 | * @buffer: The ring buffer to reset a per cpu buffer of | |
4157 | * @cpu: The CPU buffer to be reset | |
4158 | */ | |
4159 | void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) | |
4160 | { | |
4161 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
4162 | unsigned long flags; | |
4163 | ||
9e01c1b7 | 4164 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 4165 | return; |
7a8e76a3 | 4166 | |
83f40318 | 4167 | atomic_inc(&buffer->resize_disabled); |
41ede23e SR |
4168 | atomic_inc(&cpu_buffer->record_disabled); |
4169 | ||
83f40318 VN |
4170 | /* Make sure all commits have finished */ |
4171 | synchronize_sched(); | |
4172 | ||
5389f6fa | 4173 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
f83c9d0f | 4174 | |
41b6a95d SR |
4175 | if (RB_WARN_ON(cpu_buffer, local_read(&cpu_buffer->committing))) |
4176 | goto out; | |
4177 | ||
0199c4e6 | 4178 | arch_spin_lock(&cpu_buffer->lock); |
7a8e76a3 SR |
4179 | |
4180 | rb_reset_cpu(cpu_buffer); | |
4181 | ||
0199c4e6 | 4182 | arch_spin_unlock(&cpu_buffer->lock); |
f83c9d0f | 4183 | |
41b6a95d | 4184 | out: |
5389f6fa | 4185 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
41ede23e SR |
4186 | |
4187 | atomic_dec(&cpu_buffer->record_disabled); | |
83f40318 | 4188 | atomic_dec(&buffer->resize_disabled); |
7a8e76a3 | 4189 | } |
c4f50183 | 4190 | EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); |
7a8e76a3 SR |
4191 | |
4192 | /** | |
4193 | * ring_buffer_reset - reset a ring buffer | |
4194 | * @buffer: The ring buffer to reset all cpu buffers | |
4195 | */ | |
4196 | void ring_buffer_reset(struct ring_buffer *buffer) | |
4197 | { | |
7a8e76a3 SR |
4198 | int cpu; |
4199 | ||
7a8e76a3 | 4200 | for_each_buffer_cpu(buffer, cpu) |
d769041f | 4201 | ring_buffer_reset_cpu(buffer, cpu); |
7a8e76a3 | 4202 | } |
c4f50183 | 4203 | EXPORT_SYMBOL_GPL(ring_buffer_reset); |
7a8e76a3 SR |
4204 | |
4205 | /** | |
4206 | * rind_buffer_empty - is the ring buffer empty? | |
4207 | * @buffer: The ring buffer to test | |
4208 | */ | |
4209 | int ring_buffer_empty(struct ring_buffer *buffer) | |
4210 | { | |
4211 | struct ring_buffer_per_cpu *cpu_buffer; | |
d4788207 | 4212 | unsigned long flags; |
8d707e8e | 4213 | int dolock; |
7a8e76a3 | 4214 | int cpu; |
d4788207 | 4215 | int ret; |
7a8e76a3 | 4216 | |
8d707e8e | 4217 | dolock = rb_ok_to_lock(); |
7a8e76a3 SR |
4218 | |
4219 | /* yes this is racy, but if you don't like the race, lock the buffer */ | |
4220 | for_each_buffer_cpu(buffer, cpu) { | |
4221 | cpu_buffer = buffer->buffers[cpu]; | |
8d707e8e SR |
4222 | local_irq_save(flags); |
4223 | if (dolock) | |
5389f6fa | 4224 | raw_spin_lock(&cpu_buffer->reader_lock); |
d4788207 | 4225 | ret = rb_per_cpu_empty(cpu_buffer); |
8d707e8e | 4226 | if (dolock) |
5389f6fa | 4227 | raw_spin_unlock(&cpu_buffer->reader_lock); |
8d707e8e SR |
4228 | local_irq_restore(flags); |
4229 | ||
d4788207 | 4230 | if (!ret) |
7a8e76a3 SR |
4231 | return 0; |
4232 | } | |
554f786e | 4233 | |
7a8e76a3 SR |
4234 | return 1; |
4235 | } | |
c4f50183 | 4236 | EXPORT_SYMBOL_GPL(ring_buffer_empty); |
7a8e76a3 SR |
4237 | |
4238 | /** | |
4239 | * ring_buffer_empty_cpu - is a cpu buffer of a ring buffer empty? | |
4240 | * @buffer: The ring buffer | |
4241 | * @cpu: The CPU buffer to test | |
4242 | */ | |
4243 | int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) | |
4244 | { | |
4245 | struct ring_buffer_per_cpu *cpu_buffer; | |
d4788207 | 4246 | unsigned long flags; |
8d707e8e | 4247 | int dolock; |
8aabee57 | 4248 | int ret; |
7a8e76a3 | 4249 | |
9e01c1b7 | 4250 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 4251 | return 1; |
7a8e76a3 | 4252 | |
8d707e8e SR |
4253 | dolock = rb_ok_to_lock(); |
4254 | ||
7a8e76a3 | 4255 | cpu_buffer = buffer->buffers[cpu]; |
8d707e8e SR |
4256 | local_irq_save(flags); |
4257 | if (dolock) | |
5389f6fa | 4258 | raw_spin_lock(&cpu_buffer->reader_lock); |
554f786e | 4259 | ret = rb_per_cpu_empty(cpu_buffer); |
8d707e8e | 4260 | if (dolock) |
5389f6fa | 4261 | raw_spin_unlock(&cpu_buffer->reader_lock); |
8d707e8e | 4262 | local_irq_restore(flags); |
554f786e SR |
4263 | |
4264 | return ret; | |
7a8e76a3 | 4265 | } |
c4f50183 | 4266 | EXPORT_SYMBOL_GPL(ring_buffer_empty_cpu); |
7a8e76a3 | 4267 | |
85bac32c | 4268 | #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP |
7a8e76a3 SR |
4269 | /** |
4270 | * ring_buffer_swap_cpu - swap a CPU buffer between two ring buffers | |
4271 | * @buffer_a: One buffer to swap with | |
4272 | * @buffer_b: The other buffer to swap with | |
4273 | * | |
4274 | * This function is useful for tracers that want to take a "snapshot" | |
4275 | * of a CPU buffer and has another back up buffer lying around. | |
4276 | * it is expected that the tracer handles the cpu buffer not being | |
4277 | * used at the moment. | |
4278 | */ | |
4279 | int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, | |
4280 | struct ring_buffer *buffer_b, int cpu) | |
4281 | { | |
4282 | struct ring_buffer_per_cpu *cpu_buffer_a; | |
4283 | struct ring_buffer_per_cpu *cpu_buffer_b; | |
554f786e SR |
4284 | int ret = -EINVAL; |
4285 | ||
9e01c1b7 RR |
4286 | if (!cpumask_test_cpu(cpu, buffer_a->cpumask) || |
4287 | !cpumask_test_cpu(cpu, buffer_b->cpumask)) | |
554f786e | 4288 | goto out; |
7a8e76a3 | 4289 | |
438ced17 VN |
4290 | cpu_buffer_a = buffer_a->buffers[cpu]; |
4291 | cpu_buffer_b = buffer_b->buffers[cpu]; | |
4292 | ||
7a8e76a3 | 4293 | /* At least make sure the two buffers are somewhat the same */ |
438ced17 | 4294 | if (cpu_buffer_a->nr_pages != cpu_buffer_b->nr_pages) |
554f786e SR |
4295 | goto out; |
4296 | ||
4297 | ret = -EAGAIN; | |
7a8e76a3 | 4298 | |
97b17efe | 4299 | if (ring_buffer_flags != RB_BUFFERS_ON) |
554f786e | 4300 | goto out; |
97b17efe SR |
4301 | |
4302 | if (atomic_read(&buffer_a->record_disabled)) | |
554f786e | 4303 | goto out; |
97b17efe SR |
4304 | |
4305 | if (atomic_read(&buffer_b->record_disabled)) | |
554f786e | 4306 | goto out; |
97b17efe | 4307 | |
97b17efe | 4308 | if (atomic_read(&cpu_buffer_a->record_disabled)) |
554f786e | 4309 | goto out; |
97b17efe SR |
4310 | |
4311 | if (atomic_read(&cpu_buffer_b->record_disabled)) | |
554f786e | 4312 | goto out; |
97b17efe | 4313 | |
7a8e76a3 SR |
4314 | /* |
4315 | * We can't do a synchronize_sched here because this | |
4316 | * function can be called in atomic context. | |
4317 | * Normally this will be called from the same CPU as cpu. | |
4318 | * If not it's up to the caller to protect this. | |
4319 | */ | |
4320 | atomic_inc(&cpu_buffer_a->record_disabled); | |
4321 | atomic_inc(&cpu_buffer_b->record_disabled); | |
4322 | ||
98277991 SR |
4323 | ret = -EBUSY; |
4324 | if (local_read(&cpu_buffer_a->committing)) | |
4325 | goto out_dec; | |
4326 | if (local_read(&cpu_buffer_b->committing)) | |
4327 | goto out_dec; | |
4328 | ||
7a8e76a3 SR |
4329 | buffer_a->buffers[cpu] = cpu_buffer_b; |
4330 | buffer_b->buffers[cpu] = cpu_buffer_a; | |
4331 | ||
4332 | cpu_buffer_b->buffer = buffer_a; | |
4333 | cpu_buffer_a->buffer = buffer_b; | |
4334 | ||
98277991 SR |
4335 | ret = 0; |
4336 | ||
4337 | out_dec: | |
7a8e76a3 SR |
4338 | atomic_dec(&cpu_buffer_a->record_disabled); |
4339 | atomic_dec(&cpu_buffer_b->record_disabled); | |
554f786e | 4340 | out: |
554f786e | 4341 | return ret; |
7a8e76a3 | 4342 | } |
c4f50183 | 4343 | EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu); |
85bac32c | 4344 | #endif /* CONFIG_RING_BUFFER_ALLOW_SWAP */ |
7a8e76a3 | 4345 | |
8789a9e7 SR |
4346 | /** |
4347 | * ring_buffer_alloc_read_page - allocate a page to read from buffer | |
4348 | * @buffer: the buffer to allocate for. | |
4349 | * | |
4350 | * This function is used in conjunction with ring_buffer_read_page. | |
4351 | * When reading a full page from the ring buffer, these functions | |
4352 | * can be used to speed up the process. The calling function should | |
4353 | * allocate a few pages first with this function. Then when it | |
4354 | * needs to get pages from the ring buffer, it passes the result | |
4355 | * of this function into ring_buffer_read_page, which will swap | |
4356 | * the page that was allocated, with the read page of the buffer. | |
4357 | * | |
4358 | * Returns: | |
4359 | * The page allocated, or NULL on error. | |
4360 | */ | |
7ea59064 | 4361 | void *ring_buffer_alloc_read_page(struct ring_buffer *buffer, int cpu) |
8789a9e7 | 4362 | { |
044fa782 | 4363 | struct buffer_data_page *bpage; |
7ea59064 | 4364 | struct page *page; |
8789a9e7 | 4365 | |
d7ec4bfe VN |
4366 | page = alloc_pages_node(cpu_to_node(cpu), |
4367 | GFP_KERNEL | __GFP_NORETRY, 0); | |
7ea59064 | 4368 | if (!page) |
8789a9e7 SR |
4369 | return NULL; |
4370 | ||
7ea59064 | 4371 | bpage = page_address(page); |
8789a9e7 | 4372 | |
ef7a4a16 SR |
4373 | rb_init_page(bpage); |
4374 | ||
044fa782 | 4375 | return bpage; |
8789a9e7 | 4376 | } |
d6ce96da | 4377 | EXPORT_SYMBOL_GPL(ring_buffer_alloc_read_page); |
8789a9e7 SR |
4378 | |
4379 | /** | |
4380 | * ring_buffer_free_read_page - free an allocated read page | |
4381 | * @buffer: the buffer the page was allocate for | |
4382 | * @data: the page to free | |
4383 | * | |
4384 | * Free a page allocated from ring_buffer_alloc_read_page. | |
4385 | */ | |
4386 | void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data) | |
4387 | { | |
4388 | free_page((unsigned long)data); | |
4389 | } | |
d6ce96da | 4390 | EXPORT_SYMBOL_GPL(ring_buffer_free_read_page); |
8789a9e7 SR |
4391 | |
4392 | /** | |
4393 | * ring_buffer_read_page - extract a page from the ring buffer | |
4394 | * @buffer: buffer to extract from | |
4395 | * @data_page: the page to use allocated from ring_buffer_alloc_read_page | |
ef7a4a16 | 4396 | * @len: amount to extract |
8789a9e7 SR |
4397 | * @cpu: the cpu of the buffer to extract |
4398 | * @full: should the extraction only happen when the page is full. | |
4399 | * | |
4400 | * This function will pull out a page from the ring buffer and consume it. | |
4401 | * @data_page must be the address of the variable that was returned | |
4402 | * from ring_buffer_alloc_read_page. This is because the page might be used | |
4403 | * to swap with a page in the ring buffer. | |
4404 | * | |
4405 | * for example: | |
b85fa01e | 4406 | * rpage = ring_buffer_alloc_read_page(buffer); |
8789a9e7 SR |
4407 | * if (!rpage) |
4408 | * return error; | |
ef7a4a16 | 4409 | * ret = ring_buffer_read_page(buffer, &rpage, len, cpu, 0); |
667d2412 LJ |
4410 | * if (ret >= 0) |
4411 | * process_page(rpage, ret); | |
8789a9e7 SR |
4412 | * |
4413 | * When @full is set, the function will not return true unless | |
4414 | * the writer is off the reader page. | |
4415 | * | |
4416 | * Note: it is up to the calling functions to handle sleeps and wakeups. | |
4417 | * The ring buffer can be used anywhere in the kernel and can not | |
4418 | * blindly call wake_up. The layer that uses the ring buffer must be | |
4419 | * responsible for that. | |
4420 | * | |
4421 | * Returns: | |
667d2412 LJ |
4422 | * >=0 if data has been transferred, returns the offset of consumed data. |
4423 | * <0 if no data has been transferred. | |
8789a9e7 SR |
4424 | */ |
4425 | int ring_buffer_read_page(struct ring_buffer *buffer, | |
ef7a4a16 | 4426 | void **data_page, size_t len, int cpu, int full) |
8789a9e7 SR |
4427 | { |
4428 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
4429 | struct ring_buffer_event *event; | |
044fa782 | 4430 | struct buffer_data_page *bpage; |
ef7a4a16 | 4431 | struct buffer_page *reader; |
ff0ff84a | 4432 | unsigned long missed_events; |
8789a9e7 | 4433 | unsigned long flags; |
ef7a4a16 | 4434 | unsigned int commit; |
667d2412 | 4435 | unsigned int read; |
4f3640f8 | 4436 | u64 save_timestamp; |
667d2412 | 4437 | int ret = -1; |
8789a9e7 | 4438 | |
554f786e SR |
4439 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
4440 | goto out; | |
4441 | ||
474d32b6 SR |
4442 | /* |
4443 | * If len is not big enough to hold the page header, then | |
4444 | * we can not copy anything. | |
4445 | */ | |
4446 | if (len <= BUF_PAGE_HDR_SIZE) | |
554f786e | 4447 | goto out; |
474d32b6 SR |
4448 | |
4449 | len -= BUF_PAGE_HDR_SIZE; | |
4450 | ||
8789a9e7 | 4451 | if (!data_page) |
554f786e | 4452 | goto out; |
8789a9e7 | 4453 | |
044fa782 SR |
4454 | bpage = *data_page; |
4455 | if (!bpage) | |
554f786e | 4456 | goto out; |
8789a9e7 | 4457 | |
5389f6fa | 4458 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
8789a9e7 | 4459 | |
ef7a4a16 SR |
4460 | reader = rb_get_reader_page(cpu_buffer); |
4461 | if (!reader) | |
554f786e | 4462 | goto out_unlock; |
8789a9e7 | 4463 | |
ef7a4a16 SR |
4464 | event = rb_reader_event(cpu_buffer); |
4465 | ||
4466 | read = reader->read; | |
4467 | commit = rb_page_commit(reader); | |
667d2412 | 4468 | |
66a8cb95 | 4469 | /* Check if any events were dropped */ |
ff0ff84a | 4470 | missed_events = cpu_buffer->lost_events; |
66a8cb95 | 4471 | |
8789a9e7 | 4472 | /* |
474d32b6 SR |
4473 | * If this page has been partially read or |
4474 | * if len is not big enough to read the rest of the page or | |
4475 | * a writer is still on the page, then | |
4476 | * we must copy the data from the page to the buffer. | |
4477 | * Otherwise, we can simply swap the page with the one passed in. | |
8789a9e7 | 4478 | */ |
474d32b6 | 4479 | if (read || (len < (commit - read)) || |
ef7a4a16 | 4480 | cpu_buffer->reader_page == cpu_buffer->commit_page) { |
667d2412 | 4481 | struct buffer_data_page *rpage = cpu_buffer->reader_page->page; |
474d32b6 SR |
4482 | unsigned int rpos = read; |
4483 | unsigned int pos = 0; | |
ef7a4a16 | 4484 | unsigned int size; |
8789a9e7 SR |
4485 | |
4486 | if (full) | |
554f786e | 4487 | goto out_unlock; |
8789a9e7 | 4488 | |
ef7a4a16 SR |
4489 | if (len > (commit - read)) |
4490 | len = (commit - read); | |
4491 | ||
69d1b839 SR |
4492 | /* Always keep the time extend and data together */ |
4493 | size = rb_event_ts_length(event); | |
ef7a4a16 SR |
4494 | |
4495 | if (len < size) | |
554f786e | 4496 | goto out_unlock; |
ef7a4a16 | 4497 | |
4f3640f8 SR |
4498 | /* save the current timestamp, since the user will need it */ |
4499 | save_timestamp = cpu_buffer->read_stamp; | |
4500 | ||
ef7a4a16 SR |
4501 | /* Need to copy one event at a time */ |
4502 | do { | |
e1e35927 DS |
4503 | /* We need the size of one event, because |
4504 | * rb_advance_reader only advances by one event, | |
4505 | * whereas rb_event_ts_length may include the size of | |
4506 | * one or two events. | |
4507 | * We have already ensured there's enough space if this | |
4508 | * is a time extend. */ | |
4509 | size = rb_event_length(event); | |
474d32b6 | 4510 | memcpy(bpage->data + pos, rpage->data + rpos, size); |
ef7a4a16 SR |
4511 | |
4512 | len -= size; | |
4513 | ||
4514 | rb_advance_reader(cpu_buffer); | |
474d32b6 SR |
4515 | rpos = reader->read; |
4516 | pos += size; | |
ef7a4a16 | 4517 | |
18fab912 HY |
4518 | if (rpos >= commit) |
4519 | break; | |
4520 | ||
ef7a4a16 | 4521 | event = rb_reader_event(cpu_buffer); |
69d1b839 SR |
4522 | /* Always keep the time extend and data together */ |
4523 | size = rb_event_ts_length(event); | |
e1e35927 | 4524 | } while (len >= size); |
667d2412 LJ |
4525 | |
4526 | /* update bpage */ | |
ef7a4a16 | 4527 | local_set(&bpage->commit, pos); |
4f3640f8 | 4528 | bpage->time_stamp = save_timestamp; |
ef7a4a16 | 4529 | |
474d32b6 SR |
4530 | /* we copied everything to the beginning */ |
4531 | read = 0; | |
8789a9e7 | 4532 | } else { |
afbab76a | 4533 | /* update the entry counter */ |
77ae365e | 4534 | cpu_buffer->read += rb_page_entries(reader); |
c64e148a | 4535 | cpu_buffer->read_bytes += BUF_PAGE_SIZE; |
afbab76a | 4536 | |
8789a9e7 | 4537 | /* swap the pages */ |
044fa782 | 4538 | rb_init_page(bpage); |
ef7a4a16 SR |
4539 | bpage = reader->page; |
4540 | reader->page = *data_page; | |
4541 | local_set(&reader->write, 0); | |
778c55d4 | 4542 | local_set(&reader->entries, 0); |
ef7a4a16 | 4543 | reader->read = 0; |
044fa782 | 4544 | *data_page = bpage; |
ff0ff84a SR |
4545 | |
4546 | /* | |
4547 | * Use the real_end for the data size, | |
4548 | * This gives us a chance to store the lost events | |
4549 | * on the page. | |
4550 | */ | |
4551 | if (reader->real_end) | |
4552 | local_set(&bpage->commit, reader->real_end); | |
8789a9e7 | 4553 | } |
667d2412 | 4554 | ret = read; |
8789a9e7 | 4555 | |
66a8cb95 | 4556 | cpu_buffer->lost_events = 0; |
2711ca23 SR |
4557 | |
4558 | commit = local_read(&bpage->commit); | |
66a8cb95 SR |
4559 | /* |
4560 | * Set a flag in the commit field if we lost events | |
4561 | */ | |
ff0ff84a | 4562 | if (missed_events) { |
ff0ff84a SR |
4563 | /* If there is room at the end of the page to save the |
4564 | * missed events, then record it there. | |
4565 | */ | |
4566 | if (BUF_PAGE_SIZE - commit >= sizeof(missed_events)) { | |
4567 | memcpy(&bpage->data[commit], &missed_events, | |
4568 | sizeof(missed_events)); | |
4569 | local_add(RB_MISSED_STORED, &bpage->commit); | |
2711ca23 | 4570 | commit += sizeof(missed_events); |
ff0ff84a | 4571 | } |
66a8cb95 | 4572 | local_add(RB_MISSED_EVENTS, &bpage->commit); |
ff0ff84a | 4573 | } |
66a8cb95 | 4574 | |
2711ca23 SR |
4575 | /* |
4576 | * This page may be off to user land. Zero it out here. | |
4577 | */ | |
4578 | if (commit < BUF_PAGE_SIZE) | |
4579 | memset(&bpage->data[commit], 0, BUF_PAGE_SIZE - commit); | |
4580 | ||
554f786e | 4581 | out_unlock: |
5389f6fa | 4582 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
8789a9e7 | 4583 | |
554f786e | 4584 | out: |
8789a9e7 SR |
4585 | return ret; |
4586 | } | |
d6ce96da | 4587 | EXPORT_SYMBOL_GPL(ring_buffer_read_page); |
8789a9e7 | 4588 | |
59222efe | 4589 | #ifdef CONFIG_HOTPLUG_CPU |
09c9e84d FW |
4590 | static int rb_cpu_notify(struct notifier_block *self, |
4591 | unsigned long action, void *hcpu) | |
554f786e SR |
4592 | { |
4593 | struct ring_buffer *buffer = | |
4594 | container_of(self, struct ring_buffer, cpu_notify); | |
4595 | long cpu = (long)hcpu; | |
438ced17 VN |
4596 | int cpu_i, nr_pages_same; |
4597 | unsigned int nr_pages; | |
554f786e SR |
4598 | |
4599 | switch (action) { | |
4600 | case CPU_UP_PREPARE: | |
4601 | case CPU_UP_PREPARE_FROZEN: | |
3f237a79 | 4602 | if (cpumask_test_cpu(cpu, buffer->cpumask)) |
554f786e SR |
4603 | return NOTIFY_OK; |
4604 | ||
438ced17 VN |
4605 | nr_pages = 0; |
4606 | nr_pages_same = 1; | |
4607 | /* check if all cpu sizes are same */ | |
4608 | for_each_buffer_cpu(buffer, cpu_i) { | |
4609 | /* fill in the size from first enabled cpu */ | |
4610 | if (nr_pages == 0) | |
4611 | nr_pages = buffer->buffers[cpu_i]->nr_pages; | |
4612 | if (nr_pages != buffer->buffers[cpu_i]->nr_pages) { | |
4613 | nr_pages_same = 0; | |
4614 | break; | |
4615 | } | |
4616 | } | |
4617 | /* allocate minimum pages, user can later expand it */ | |
4618 | if (!nr_pages_same) | |
4619 | nr_pages = 2; | |
554f786e | 4620 | buffer->buffers[cpu] = |
438ced17 | 4621 | rb_allocate_cpu_buffer(buffer, nr_pages, cpu); |
554f786e SR |
4622 | if (!buffer->buffers[cpu]) { |
4623 | WARN(1, "failed to allocate ring buffer on CPU %ld\n", | |
4624 | cpu); | |
4625 | return NOTIFY_OK; | |
4626 | } | |
4627 | smp_wmb(); | |
3f237a79 | 4628 | cpumask_set_cpu(cpu, buffer->cpumask); |
554f786e SR |
4629 | break; |
4630 | case CPU_DOWN_PREPARE: | |
4631 | case CPU_DOWN_PREPARE_FROZEN: | |
4632 | /* | |
4633 | * Do nothing. | |
4634 | * If we were to free the buffer, then the user would | |
4635 | * lose any trace that was in the buffer. | |
4636 | */ | |
4637 | break; | |
4638 | default: | |
4639 | break; | |
4640 | } | |
4641 | return NOTIFY_OK; | |
4642 | } | |
4643 | #endif | |
6c43e554 SRRH |
4644 | |
4645 | #ifdef CONFIG_RING_BUFFER_STARTUP_TEST | |
4646 | /* | |
4647 | * This is a basic integrity check of the ring buffer. | |
4648 | * Late in the boot cycle this test will run when configured in. | |
4649 | * It will kick off a thread per CPU that will go into a loop | |
4650 | * writing to the per cpu ring buffer various sizes of data. | |
4651 | * Some of the data will be large items, some small. | |
4652 | * | |
4653 | * Another thread is created that goes into a spin, sending out | |
4654 | * IPIs to the other CPUs to also write into the ring buffer. | |
4655 | * this is to test the nesting ability of the buffer. | |
4656 | * | |
4657 | * Basic stats are recorded and reported. If something in the | |
4658 | * ring buffer should happen that's not expected, a big warning | |
4659 | * is displayed and all ring buffers are disabled. | |
4660 | */ | |
4661 | static struct task_struct *rb_threads[NR_CPUS] __initdata; | |
4662 | ||
4663 | struct rb_test_data { | |
4664 | struct ring_buffer *buffer; | |
4665 | unsigned long events; | |
4666 | unsigned long bytes_written; | |
4667 | unsigned long bytes_alloc; | |
4668 | unsigned long bytes_dropped; | |
4669 | unsigned long events_nested; | |
4670 | unsigned long bytes_written_nested; | |
4671 | unsigned long bytes_alloc_nested; | |
4672 | unsigned long bytes_dropped_nested; | |
4673 | int min_size_nested; | |
4674 | int max_size_nested; | |
4675 | int max_size; | |
4676 | int min_size; | |
4677 | int cpu; | |
4678 | int cnt; | |
4679 | }; | |
4680 | ||
4681 | static struct rb_test_data rb_data[NR_CPUS] __initdata; | |
4682 | ||
4683 | /* 1 meg per cpu */ | |
4684 | #define RB_TEST_BUFFER_SIZE 1048576 | |
4685 | ||
4686 | static char rb_string[] __initdata = | |
4687 | "abcdefghijklmnopqrstuvwxyz1234567890!@#$%^&*()?+\\" | |
4688 | "?+|:';\",.<>/?abcdefghijklmnopqrstuvwxyz1234567890" | |
4689 | "!@#$%^&*()?+\\?+|:';\",.<>/?abcdefghijklmnopqrstuv"; | |
4690 | ||
4691 | static bool rb_test_started __initdata; | |
4692 | ||
4693 | struct rb_item { | |
4694 | int size; | |
4695 | char str[]; | |
4696 | }; | |
4697 | ||
4698 | static __init int rb_write_something(struct rb_test_data *data, bool nested) | |
4699 | { | |
4700 | struct ring_buffer_event *event; | |
4701 | struct rb_item *item; | |
4702 | bool started; | |
4703 | int event_len; | |
4704 | int size; | |
4705 | int len; | |
4706 | int cnt; | |
4707 | ||
4708 | /* Have nested writes different that what is written */ | |
4709 | cnt = data->cnt + (nested ? 27 : 0); | |
4710 | ||
4711 | /* Multiply cnt by ~e, to make some unique increment */ | |
4712 | size = (data->cnt * 68 / 25) % (sizeof(rb_string) - 1); | |
4713 | ||
4714 | len = size + sizeof(struct rb_item); | |
4715 | ||
4716 | started = rb_test_started; | |
4717 | /* read rb_test_started before checking buffer enabled */ | |
4718 | smp_rmb(); | |
4719 | ||
4720 | event = ring_buffer_lock_reserve(data->buffer, len); | |
4721 | if (!event) { | |
4722 | /* Ignore dropped events before test starts. */ | |
4723 | if (started) { | |
4724 | if (nested) | |
4725 | data->bytes_dropped += len; | |
4726 | else | |
4727 | data->bytes_dropped_nested += len; | |
4728 | } | |
4729 | return len; | |
4730 | } | |
4731 | ||
4732 | event_len = ring_buffer_event_length(event); | |
4733 | ||
4734 | if (RB_WARN_ON(data->buffer, event_len < len)) | |
4735 | goto out; | |
4736 | ||
4737 | item = ring_buffer_event_data(event); | |
4738 | item->size = size; | |
4739 | memcpy(item->str, rb_string, size); | |
4740 | ||
4741 | if (nested) { | |
4742 | data->bytes_alloc_nested += event_len; | |
4743 | data->bytes_written_nested += len; | |
4744 | data->events_nested++; | |
4745 | if (!data->min_size_nested || len < data->min_size_nested) | |
4746 | data->min_size_nested = len; | |
4747 | if (len > data->max_size_nested) | |
4748 | data->max_size_nested = len; | |
4749 | } else { | |
4750 | data->bytes_alloc += event_len; | |
4751 | data->bytes_written += len; | |
4752 | data->events++; | |
4753 | if (!data->min_size || len < data->min_size) | |
4754 | data->max_size = len; | |
4755 | if (len > data->max_size) | |
4756 | data->max_size = len; | |
4757 | } | |
4758 | ||
4759 | out: | |
4760 | ring_buffer_unlock_commit(data->buffer, event); | |
4761 | ||
4762 | return 0; | |
4763 | } | |
4764 | ||
4765 | static __init int rb_test(void *arg) | |
4766 | { | |
4767 | struct rb_test_data *data = arg; | |
4768 | ||
4769 | while (!kthread_should_stop()) { | |
4770 | rb_write_something(data, false); | |
4771 | data->cnt++; | |
4772 | ||
4773 | set_current_state(TASK_INTERRUPTIBLE); | |
4774 | /* Now sleep between a min of 100-300us and a max of 1ms */ | |
4775 | usleep_range(((data->cnt % 3) + 1) * 100, 1000); | |
4776 | } | |
4777 | ||
4778 | return 0; | |
4779 | } | |
4780 | ||
4781 | static __init void rb_ipi(void *ignore) | |
4782 | { | |
4783 | struct rb_test_data *data; | |
4784 | int cpu = smp_processor_id(); | |
4785 | ||
4786 | data = &rb_data[cpu]; | |
4787 | rb_write_something(data, true); | |
4788 | } | |
4789 | ||
4790 | static __init int rb_hammer_test(void *arg) | |
4791 | { | |
4792 | while (!kthread_should_stop()) { | |
4793 | ||
4794 | /* Send an IPI to all cpus to write data! */ | |
4795 | smp_call_function(rb_ipi, NULL, 1); | |
4796 | /* No sleep, but for non preempt, let others run */ | |
4797 | schedule(); | |
4798 | } | |
4799 | ||
4800 | return 0; | |
4801 | } | |
4802 | ||
4803 | static __init int test_ringbuffer(void) | |
4804 | { | |
4805 | struct task_struct *rb_hammer; | |
4806 | struct ring_buffer *buffer; | |
4807 | int cpu; | |
4808 | int ret = 0; | |
4809 | ||
4810 | pr_info("Running ring buffer tests...\n"); | |
4811 | ||
4812 | buffer = ring_buffer_alloc(RB_TEST_BUFFER_SIZE, RB_FL_OVERWRITE); | |
4813 | if (WARN_ON(!buffer)) | |
4814 | return 0; | |
4815 | ||
4816 | /* Disable buffer so that threads can't write to it yet */ | |
4817 | ring_buffer_record_off(buffer); | |
4818 | ||
4819 | for_each_online_cpu(cpu) { | |
4820 | rb_data[cpu].buffer = buffer; | |
4821 | rb_data[cpu].cpu = cpu; | |
4822 | rb_data[cpu].cnt = cpu; | |
4823 | rb_threads[cpu] = kthread_create(rb_test, &rb_data[cpu], | |
4824 | "rbtester/%d", cpu); | |
4825 | if (WARN_ON(!rb_threads[cpu])) { | |
4826 | pr_cont("FAILED\n"); | |
4827 | ret = -1; | |
4828 | goto out_free; | |
4829 | } | |
4830 | ||
4831 | kthread_bind(rb_threads[cpu], cpu); | |
4832 | wake_up_process(rb_threads[cpu]); | |
4833 | } | |
4834 | ||
4835 | /* Now create the rb hammer! */ | |
4836 | rb_hammer = kthread_run(rb_hammer_test, NULL, "rbhammer"); | |
4837 | if (WARN_ON(!rb_hammer)) { | |
4838 | pr_cont("FAILED\n"); | |
4839 | ret = -1; | |
4840 | goto out_free; | |
4841 | } | |
4842 | ||
4843 | ring_buffer_record_on(buffer); | |
4844 | /* | |
4845 | * Show buffer is enabled before setting rb_test_started. | |
4846 | * Yes there's a small race window where events could be | |
4847 | * dropped and the thread wont catch it. But when a ring | |
4848 | * buffer gets enabled, there will always be some kind of | |
4849 | * delay before other CPUs see it. Thus, we don't care about | |
4850 | * those dropped events. We care about events dropped after | |
4851 | * the threads see that the buffer is active. | |
4852 | */ | |
4853 | smp_wmb(); | |
4854 | rb_test_started = true; | |
4855 | ||
4856 | set_current_state(TASK_INTERRUPTIBLE); | |
4857 | /* Just run for 10 seconds */; | |
4858 | schedule_timeout(10 * HZ); | |
4859 | ||
4860 | kthread_stop(rb_hammer); | |
4861 | ||
4862 | out_free: | |
4863 | for_each_online_cpu(cpu) { | |
4864 | if (!rb_threads[cpu]) | |
4865 | break; | |
4866 | kthread_stop(rb_threads[cpu]); | |
4867 | } | |
4868 | if (ret) { | |
4869 | ring_buffer_free(buffer); | |
4870 | return ret; | |
4871 | } | |
4872 | ||
4873 | /* Report! */ | |
4874 | pr_info("finished\n"); | |
4875 | for_each_online_cpu(cpu) { | |
4876 | struct ring_buffer_event *event; | |
4877 | struct rb_test_data *data = &rb_data[cpu]; | |
4878 | struct rb_item *item; | |
4879 | unsigned long total_events; | |
4880 | unsigned long total_dropped; | |
4881 | unsigned long total_written; | |
4882 | unsigned long total_alloc; | |
4883 | unsigned long total_read = 0; | |
4884 | unsigned long total_size = 0; | |
4885 | unsigned long total_len = 0; | |
4886 | unsigned long total_lost = 0; | |
4887 | unsigned long lost; | |
4888 | int big_event_size; | |
4889 | int small_event_size; | |
4890 | ||
4891 | ret = -1; | |
4892 | ||
4893 | total_events = data->events + data->events_nested; | |
4894 | total_written = data->bytes_written + data->bytes_written_nested; | |
4895 | total_alloc = data->bytes_alloc + data->bytes_alloc_nested; | |
4896 | total_dropped = data->bytes_dropped + data->bytes_dropped_nested; | |
4897 | ||
4898 | big_event_size = data->max_size + data->max_size_nested; | |
4899 | small_event_size = data->min_size + data->min_size_nested; | |
4900 | ||
4901 | pr_info("CPU %d:\n", cpu); | |
4902 | pr_info(" events: %ld\n", total_events); | |
4903 | pr_info(" dropped bytes: %ld\n", total_dropped); | |
4904 | pr_info(" alloced bytes: %ld\n", total_alloc); | |
4905 | pr_info(" written bytes: %ld\n", total_written); | |
4906 | pr_info(" biggest event: %d\n", big_event_size); | |
4907 | pr_info(" smallest event: %d\n", small_event_size); | |
4908 | ||
4909 | if (RB_WARN_ON(buffer, total_dropped)) | |
4910 | break; | |
4911 | ||
4912 | ret = 0; | |
4913 | ||
4914 | while ((event = ring_buffer_consume(buffer, cpu, NULL, &lost))) { | |
4915 | total_lost += lost; | |
4916 | item = ring_buffer_event_data(event); | |
4917 | total_len += ring_buffer_event_length(event); | |
4918 | total_size += item->size + sizeof(struct rb_item); | |
4919 | if (memcmp(&item->str[0], rb_string, item->size) != 0) { | |
4920 | pr_info("FAILED!\n"); | |
4921 | pr_info("buffer had: %.*s\n", item->size, item->str); | |
4922 | pr_info("expected: %.*s\n", item->size, rb_string); | |
4923 | RB_WARN_ON(buffer, 1); | |
4924 | ret = -1; | |
4925 | break; | |
4926 | } | |
4927 | total_read++; | |
4928 | } | |
4929 | if (ret) | |
4930 | break; | |
4931 | ||
4932 | ret = -1; | |
4933 | ||
4934 | pr_info(" read events: %ld\n", total_read); | |
4935 | pr_info(" lost events: %ld\n", total_lost); | |
4936 | pr_info(" total events: %ld\n", total_lost + total_read); | |
4937 | pr_info(" recorded len bytes: %ld\n", total_len); | |
4938 | pr_info(" recorded size bytes: %ld\n", total_size); | |
4939 | if (total_lost) | |
4940 | pr_info(" With dropped events, record len and size may not match\n" | |
4941 | " alloced and written from above\n"); | |
4942 | if (!total_lost) { | |
4943 | if (RB_WARN_ON(buffer, total_len != total_alloc || | |
4944 | total_size != total_written)) | |
4945 | break; | |
4946 | } | |
4947 | if (RB_WARN_ON(buffer, total_lost + total_read != total_events)) | |
4948 | break; | |
4949 | ||
4950 | ret = 0; | |
4951 | } | |
4952 | if (!ret) | |
4953 | pr_info("Ring buffer PASSED!\n"); | |
4954 | ||
4955 | ring_buffer_free(buffer); | |
4956 | return 0; | |
4957 | } | |
4958 | ||
4959 | late_initcall(test_ringbuffer); | |
4960 | #endif /* CONFIG_RING_BUFFER_STARTUP_TEST */ |