Commit | Line | Data |
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bcea3f96 | 1 | // SPDX-License-Identifier: GPL-2.0 |
7a8e76a3 SR |
2 | /* |
3 | * Generic ring buffer | |
4 | * | |
5 | * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com> | |
6 | */ | |
28575c61 | 7 | #include <linux/trace_recursion.h> |
af658dca | 8 | #include <linux/trace_events.h> |
7a8e76a3 | 9 | #include <linux/ring_buffer.h> |
14131f2f | 10 | #include <linux/trace_clock.h> |
e6017571 | 11 | #include <linux/sched/clock.h> |
0b07436d | 12 | #include <linux/trace_seq.h> |
7a8e76a3 | 13 | #include <linux/spinlock.h> |
15693458 | 14 | #include <linux/irq_work.h> |
a356646a | 15 | #include <linux/security.h> |
7a8e76a3 | 16 | #include <linux/uaccess.h> |
a81bd80a | 17 | #include <linux/hardirq.h> |
6c43e554 | 18 | #include <linux/kthread.h> /* for self test */ |
7a8e76a3 SR |
19 | #include <linux/module.h> |
20 | #include <linux/percpu.h> | |
21 | #include <linux/mutex.h> | |
6c43e554 | 22 | #include <linux/delay.h> |
5a0e3ad6 | 23 | #include <linux/slab.h> |
7a8e76a3 SR |
24 | #include <linux/init.h> |
25 | #include <linux/hash.h> | |
26 | #include <linux/list.h> | |
554f786e | 27 | #include <linux/cpu.h> |
927e56db | 28 | #include <linux/oom.h> |
7a8e76a3 | 29 | |
c84897c0 | 30 | #include <asm/local64.h> |
79615760 | 31 | #include <asm/local.h> |
182e9f5f | 32 | |
6695da58 SRG |
33 | /* |
34 | * The "absolute" timestamp in the buffer is only 59 bits. | |
35 | * If a clock has the 5 MSBs set, it needs to be saved and | |
36 | * reinserted. | |
37 | */ | |
38 | #define TS_MSB (0xf8ULL << 56) | |
39 | #define ABS_TS_MASK (~TS_MSB) | |
40 | ||
83f40318 VN |
41 | static void update_pages_handler(struct work_struct *work); |
42 | ||
d1b182a8 SR |
43 | /* |
44 | * The ring buffer header is special. We must manually up keep it. | |
45 | */ | |
46 | int ring_buffer_print_entry_header(struct trace_seq *s) | |
47 | { | |
c0cd93aa SRRH |
48 | trace_seq_puts(s, "# compressed entry header\n"); |
49 | trace_seq_puts(s, "\ttype_len : 5 bits\n"); | |
50 | trace_seq_puts(s, "\ttime_delta : 27 bits\n"); | |
51 | trace_seq_puts(s, "\tarray : 32 bits\n"); | |
52 | trace_seq_putc(s, '\n'); | |
53 | trace_seq_printf(s, "\tpadding : type == %d\n", | |
54 | RINGBUF_TYPE_PADDING); | |
55 | trace_seq_printf(s, "\ttime_extend : type == %d\n", | |
56 | RINGBUF_TYPE_TIME_EXTEND); | |
dc4e2801 TZ |
57 | trace_seq_printf(s, "\ttime_stamp : type == %d\n", |
58 | RINGBUF_TYPE_TIME_STAMP); | |
c0cd93aa SRRH |
59 | trace_seq_printf(s, "\tdata max type_len == %d\n", |
60 | RINGBUF_TYPE_DATA_TYPE_LEN_MAX); | |
61 | ||
62 | return !trace_seq_has_overflowed(s); | |
d1b182a8 SR |
63 | } |
64 | ||
5cc98548 SR |
65 | /* |
66 | * The ring buffer is made up of a list of pages. A separate list of pages is | |
67 | * allocated for each CPU. A writer may only write to a buffer that is | |
68 | * associated with the CPU it is currently executing on. A reader may read | |
69 | * from any per cpu buffer. | |
70 | * | |
71 | * The reader is special. For each per cpu buffer, the reader has its own | |
72 | * reader page. When a reader has read the entire reader page, this reader | |
73 | * page is swapped with another page in the ring buffer. | |
74 | * | |
75 | * Now, as long as the writer is off the reader page, the reader can do what | |
76 | * ever it wants with that page. The writer will never write to that page | |
77 | * again (as long as it is out of the ring buffer). | |
78 | * | |
79 | * Here's some silly ASCII art. | |
80 | * | |
81 | * +------+ | |
82 | * |reader| RING BUFFER | |
83 | * |page | | |
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 | * |reader| RING BUFFER | |
105 | * |page |------------------v | |
106 | * +------+ +---+ +---+ +---+ | |
107 | * ^ | |-->| |-->| | | |
108 | * | +---+ +---+ +---+ | |
109 | * | | | |
110 | * | | | |
111 | * +------------------------------+ | |
112 | * | |
113 | * | |
114 | * +------+ | |
115 | * |buffer| RING BUFFER | |
116 | * |page |------------------v | |
117 | * +------+ +---+ +---+ +---+ | |
118 | * ^ | | | |-->| | | |
119 | * | New +---+ +---+ +---+ | |
120 | * | Reader------^ | | |
121 | * | page | | |
122 | * +------------------------------+ | |
123 | * | |
124 | * | |
125 | * After we make this swap, the reader can hand this page off to the splice | |
126 | * code and be done with it. It can even allocate a new page if it needs to | |
127 | * and swap that into the ring buffer. | |
128 | * | |
129 | * We will be using cmpxchg soon to make all this lockless. | |
130 | * | |
131 | */ | |
132 | ||
499e5470 SR |
133 | /* Used for individual buffers (after the counter) */ |
134 | #define RB_BUFFER_OFF (1 << 20) | |
a3583244 | 135 | |
499e5470 | 136 | #define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data) |
033601a3 | 137 | |
e3d6bf0a | 138 | #define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array)) |
67d34724 | 139 | #define RB_ALIGNMENT 4U |
334d4169 | 140 | #define RB_MAX_SMALL_DATA (RB_ALIGNMENT * RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
c7b09308 | 141 | #define RB_EVNT_MIN_SIZE 8U /* two 32bit words */ |
adab66b7 SRV |
142 | |
143 | #ifndef CONFIG_HAVE_64BIT_ALIGNED_ACCESS | |
144 | # define RB_FORCE_8BYTE_ALIGNMENT 0 | |
145 | # define RB_ARCH_ALIGNMENT RB_ALIGNMENT | |
146 | #else | |
147 | # define RB_FORCE_8BYTE_ALIGNMENT 1 | |
148 | # define RB_ARCH_ALIGNMENT 8U | |
149 | #endif | |
150 | ||
151 | #define RB_ALIGN_DATA __aligned(RB_ARCH_ALIGNMENT) | |
649508f6 | 152 | |
334d4169 LJ |
153 | /* define RINGBUF_TYPE_DATA for 'case RINGBUF_TYPE_DATA:' */ |
154 | #define RINGBUF_TYPE_DATA 0 ... RINGBUF_TYPE_DATA_TYPE_LEN_MAX | |
7a8e76a3 SR |
155 | |
156 | enum { | |
157 | RB_LEN_TIME_EXTEND = 8, | |
dc4e2801 | 158 | RB_LEN_TIME_STAMP = 8, |
7a8e76a3 SR |
159 | }; |
160 | ||
69d1b839 SR |
161 | #define skip_time_extend(event) \ |
162 | ((struct ring_buffer_event *)((char *)event + RB_LEN_TIME_EXTEND)) | |
163 | ||
dc4e2801 TZ |
164 | #define extended_time(event) \ |
165 | (event->type_len >= RINGBUF_TYPE_TIME_EXTEND) | |
166 | ||
bc92b956 | 167 | static inline bool rb_null_event(struct ring_buffer_event *event) |
2d622719 | 168 | { |
a1863c21 | 169 | return event->type_len == RINGBUF_TYPE_PADDING && !event->time_delta; |
2d622719 TZ |
170 | } |
171 | ||
172 | static void rb_event_set_padding(struct ring_buffer_event *event) | |
173 | { | |
a1863c21 | 174 | /* padding has a NULL time_delta */ |
334d4169 | 175 | event->type_len = RINGBUF_TYPE_PADDING; |
2d622719 TZ |
176 | event->time_delta = 0; |
177 | } | |
178 | ||
34a148bf | 179 | static unsigned |
2d622719 | 180 | rb_event_data_length(struct ring_buffer_event *event) |
7a8e76a3 SR |
181 | { |
182 | unsigned length; | |
183 | ||
334d4169 LJ |
184 | if (event->type_len) |
185 | length = event->type_len * RB_ALIGNMENT; | |
2d622719 TZ |
186 | else |
187 | length = event->array[0]; | |
188 | return length + RB_EVNT_HDR_SIZE; | |
189 | } | |
190 | ||
69d1b839 SR |
191 | /* |
192 | * Return the length of the given event. Will return | |
193 | * the length of the time extend if the event is a | |
194 | * time extend. | |
195 | */ | |
196 | static inline unsigned | |
2d622719 TZ |
197 | rb_event_length(struct ring_buffer_event *event) |
198 | { | |
334d4169 | 199 | switch (event->type_len) { |
7a8e76a3 | 200 | case RINGBUF_TYPE_PADDING: |
2d622719 TZ |
201 | if (rb_null_event(event)) |
202 | /* undefined */ | |
203 | return -1; | |
334d4169 | 204 | return event->array[0] + RB_EVNT_HDR_SIZE; |
7a8e76a3 SR |
205 | |
206 | case RINGBUF_TYPE_TIME_EXTEND: | |
207 | return RB_LEN_TIME_EXTEND; | |
208 | ||
209 | case RINGBUF_TYPE_TIME_STAMP: | |
210 | return RB_LEN_TIME_STAMP; | |
211 | ||
212 | case RINGBUF_TYPE_DATA: | |
2d622719 | 213 | return rb_event_data_length(event); |
7a8e76a3 | 214 | default: |
da4d401a | 215 | WARN_ON_ONCE(1); |
7a8e76a3 SR |
216 | } |
217 | /* not hit */ | |
218 | return 0; | |
219 | } | |
220 | ||
69d1b839 SR |
221 | /* |
222 | * Return total length of time extend and data, | |
223 | * or just the event length for all other events. | |
224 | */ | |
225 | static inline unsigned | |
226 | rb_event_ts_length(struct ring_buffer_event *event) | |
227 | { | |
228 | unsigned len = 0; | |
229 | ||
dc4e2801 | 230 | if (extended_time(event)) { |
69d1b839 SR |
231 | /* time extends include the data event after it */ |
232 | len = RB_LEN_TIME_EXTEND; | |
233 | event = skip_time_extend(event); | |
234 | } | |
235 | return len + rb_event_length(event); | |
236 | } | |
237 | ||
7a8e76a3 SR |
238 | /** |
239 | * ring_buffer_event_length - return the length of the event | |
240 | * @event: the event to get the length of | |
69d1b839 SR |
241 | * |
242 | * Returns the size of the data load of a data event. | |
243 | * If the event is something other than a data event, it | |
244 | * returns the size of the event itself. With the exception | |
245 | * of a TIME EXTEND, where it still returns the size of the | |
246 | * data load of the data event after it. | |
7a8e76a3 SR |
247 | */ |
248 | unsigned ring_buffer_event_length(struct ring_buffer_event *event) | |
249 | { | |
69d1b839 SR |
250 | unsigned length; |
251 | ||
dc4e2801 | 252 | if (extended_time(event)) |
69d1b839 SR |
253 | event = skip_time_extend(event); |
254 | ||
255 | length = rb_event_length(event); | |
334d4169 | 256 | if (event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
465634ad RR |
257 | return length; |
258 | length -= RB_EVNT_HDR_SIZE; | |
259 | if (length > RB_MAX_SMALL_DATA + sizeof(event->array[0])) | |
260 | length -= sizeof(event->array[0]); | |
261 | return length; | |
7a8e76a3 | 262 | } |
c4f50183 | 263 | EXPORT_SYMBOL_GPL(ring_buffer_event_length); |
7a8e76a3 SR |
264 | |
265 | /* inline for ring buffer fast paths */ | |
929ddbf3 | 266 | static __always_inline void * |
7a8e76a3 SR |
267 | rb_event_data(struct ring_buffer_event *event) |
268 | { | |
dc4e2801 | 269 | if (extended_time(event)) |
69d1b839 | 270 | event = skip_time_extend(event); |
da4d401a | 271 | WARN_ON_ONCE(event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX); |
7a8e76a3 | 272 | /* If length is in len field, then array[0] has the data */ |
334d4169 | 273 | if (event->type_len) |
7a8e76a3 SR |
274 | return (void *)&event->array[0]; |
275 | /* Otherwise length is in array[0] and array[1] has the data */ | |
276 | return (void *)&event->array[1]; | |
277 | } | |
278 | ||
279 | /** | |
280 | * ring_buffer_event_data - return the data of the event | |
281 | * @event: the event to get the data from | |
282 | */ | |
283 | void *ring_buffer_event_data(struct ring_buffer_event *event) | |
284 | { | |
285 | return rb_event_data(event); | |
286 | } | |
c4f50183 | 287 | EXPORT_SYMBOL_GPL(ring_buffer_event_data); |
7a8e76a3 SR |
288 | |
289 | #define for_each_buffer_cpu(buffer, cpu) \ | |
9e01c1b7 | 290 | for_each_cpu(cpu, buffer->cpumask) |
7a8e76a3 | 291 | |
b23d7a5f NP |
292 | #define for_each_online_buffer_cpu(buffer, cpu) \ |
293 | for_each_cpu_and(cpu, buffer->cpumask, cpu_online_mask) | |
294 | ||
7a8e76a3 SR |
295 | #define TS_SHIFT 27 |
296 | #define TS_MASK ((1ULL << TS_SHIFT) - 1) | |
297 | #define TS_DELTA_TEST (~TS_MASK) | |
298 | ||
e20044f7 SRV |
299 | static u64 rb_event_time_stamp(struct ring_buffer_event *event) |
300 | { | |
301 | u64 ts; | |
302 | ||
303 | ts = event->array[0]; | |
304 | ts <<= TS_SHIFT; | |
305 | ts += event->time_delta; | |
306 | ||
307 | return ts; | |
308 | } | |
309 | ||
66a8cb95 SR |
310 | /* Flag when events were overwritten */ |
311 | #define RB_MISSED_EVENTS (1 << 31) | |
ff0ff84a SR |
312 | /* Missed count stored at end */ |
313 | #define RB_MISSED_STORED (1 << 30) | |
66a8cb95 | 314 | |
abc9b56d | 315 | struct buffer_data_page { |
e4c2ce82 | 316 | u64 time_stamp; /* page time stamp */ |
c3706f00 | 317 | local_t commit; /* write committed index */ |
649508f6 | 318 | unsigned char data[] RB_ALIGN_DATA; /* data of buffer page */ |
abc9b56d SR |
319 | }; |
320 | ||
bce761d7 TSV |
321 | struct buffer_data_read_page { |
322 | unsigned order; /* order of the page */ | |
323 | struct buffer_data_page *data; /* actual data, stored in this page */ | |
324 | }; | |
325 | ||
77ae365e SR |
326 | /* |
327 | * Note, the buffer_page list must be first. The buffer pages | |
328 | * are allocated in cache lines, which means that each buffer | |
329 | * page will be at the beginning of a cache line, and thus | |
330 | * the least significant bits will be zero. We use this to | |
331 | * add flags in the list struct pointers, to make the ring buffer | |
332 | * lockless. | |
333 | */ | |
abc9b56d | 334 | struct buffer_page { |
778c55d4 | 335 | struct list_head list; /* list of buffer pages */ |
abc9b56d | 336 | local_t write; /* index for next write */ |
6f807acd | 337 | unsigned read; /* index for next read */ |
778c55d4 | 338 | local_t entries; /* entries on this page */ |
ff0ff84a | 339 | unsigned long real_end; /* real end of data */ |
f9b94daa | 340 | unsigned order; /* order of the page */ |
abc9b56d | 341 | struct buffer_data_page *page; /* Actual data page */ |
7a8e76a3 SR |
342 | }; |
343 | ||
77ae365e SR |
344 | /* |
345 | * The buffer page counters, write and entries, must be reset | |
346 | * atomically when crossing page boundaries. To synchronize this | |
347 | * update, two counters are inserted into the number. One is | |
348 | * the actual counter for the write position or count on the page. | |
349 | * | |
350 | * The other is a counter of updaters. Before an update happens | |
351 | * the update partition of the counter is incremented. This will | |
352 | * allow the updater to update the counter atomically. | |
353 | * | |
354 | * The counter is 20 bits, and the state data is 12. | |
355 | */ | |
356 | #define RB_WRITE_MASK 0xfffff | |
357 | #define RB_WRITE_INTCNT (1 << 20) | |
358 | ||
044fa782 | 359 | static void rb_init_page(struct buffer_data_page *bpage) |
abc9b56d | 360 | { |
044fa782 | 361 | local_set(&bpage->commit, 0); |
abc9b56d SR |
362 | } |
363 | ||
45d99ea4 ZY |
364 | static __always_inline unsigned int rb_page_commit(struct buffer_page *bpage) |
365 | { | |
366 | return local_read(&bpage->page->commit); | |
367 | } | |
368 | ||
34a148bf | 369 | static void free_buffer_page(struct buffer_page *bpage) |
ed56829c | 370 | { |
f9b94daa | 371 | free_pages((unsigned long)bpage->page, bpage->order); |
e4c2ce82 | 372 | kfree(bpage); |
ed56829c SR |
373 | } |
374 | ||
7a8e76a3 SR |
375 | /* |
376 | * We need to fit the time_stamp delta into 27 bits. | |
377 | */ | |
bc92b956 | 378 | static inline bool test_time_stamp(u64 delta) |
7a8e76a3 | 379 | { |
bc92b956 | 380 | return !!(delta & TS_DELTA_TEST); |
7a8e76a3 SR |
381 | } |
382 | ||
15693458 SRRH |
383 | struct rb_irq_work { |
384 | struct irq_work work; | |
385 | wait_queue_head_t waiters; | |
1e0d6714 | 386 | wait_queue_head_t full_waiters; |
15693458 | 387 | bool waiters_pending; |
1e0d6714 SRRH |
388 | bool full_waiters_pending; |
389 | bool wakeup_full; | |
15693458 SRRH |
390 | }; |
391 | ||
fcc742ea SRRH |
392 | /* |
393 | * Structure to hold event state and handle nested events. | |
394 | */ | |
395 | struct rb_event_info { | |
396 | u64 ts; | |
397 | u64 delta; | |
58fbc3c6 SRV |
398 | u64 before; |
399 | u64 after; | |
fcc742ea SRRH |
400 | unsigned long length; |
401 | struct buffer_page *tail_page; | |
402 | int add_timestamp; | |
403 | }; | |
404 | ||
a389d86f SRV |
405 | /* |
406 | * Used for the add_timestamp | |
407 | * NONE | |
7c4b4a51 SRV |
408 | * EXTEND - wants a time extend |
409 | * ABSOLUTE - the buffer requests all events to have absolute time stamps | |
a389d86f SRV |
410 | * FORCE - force a full time stamp. |
411 | */ | |
412 | enum { | |
7c4b4a51 SRV |
413 | RB_ADD_STAMP_NONE = 0, |
414 | RB_ADD_STAMP_EXTEND = BIT(1), | |
415 | RB_ADD_STAMP_ABSOLUTE = BIT(2), | |
416 | RB_ADD_STAMP_FORCE = BIT(3) | |
a389d86f | 417 | }; |
a497adb4 SRRH |
418 | /* |
419 | * Used for which event context the event is in. | |
b02414c8 SRV |
420 | * TRANSITION = 0 |
421 | * NMI = 1 | |
422 | * IRQ = 2 | |
423 | * SOFTIRQ = 3 | |
424 | * NORMAL = 4 | |
a497adb4 SRRH |
425 | * |
426 | * See trace_recursive_lock() comment below for more details. | |
427 | */ | |
428 | enum { | |
b02414c8 | 429 | RB_CTX_TRANSITION, |
a497adb4 SRRH |
430 | RB_CTX_NMI, |
431 | RB_CTX_IRQ, | |
432 | RB_CTX_SOFTIRQ, | |
433 | RB_CTX_NORMAL, | |
434 | RB_CTX_MAX | |
435 | }; | |
436 | ||
10464b4a SRV |
437 | struct rb_time_struct { |
438 | local64_t time; | |
439 | }; | |
10464b4a SRV |
440 | typedef struct rb_time_struct rb_time_t; |
441 | ||
8672e494 SRV |
442 | #define MAX_NEST 5 |
443 | ||
7a8e76a3 SR |
444 | /* |
445 | * head_page == tail_page && head == tail then buffer is empty. | |
446 | */ | |
447 | struct ring_buffer_per_cpu { | |
448 | int cpu; | |
985023de | 449 | atomic_t record_disabled; |
07b8b10e | 450 | atomic_t resize_disabled; |
13292494 | 451 | struct trace_buffer *buffer; |
5389f6fa | 452 | raw_spinlock_t reader_lock; /* serialize readers */ |
445c8951 | 453 | arch_spinlock_t lock; |
7a8e76a3 | 454 | struct lock_class_key lock_key; |
73a757e6 | 455 | struct buffer_data_page *free_page; |
9b94a8fb | 456 | unsigned long nr_pages; |
58a09ec6 | 457 | unsigned int current_context; |
3adc54fa | 458 | struct list_head *pages; |
6f807acd SR |
459 | struct buffer_page *head_page; /* read from head */ |
460 | struct buffer_page *tail_page; /* write to tail */ | |
c3706f00 | 461 | struct buffer_page *commit_page; /* committed pages */ |
d769041f | 462 | struct buffer_page *reader_page; |
66a8cb95 SR |
463 | unsigned long lost_events; |
464 | unsigned long last_overrun; | |
8e012066 | 465 | unsigned long nest; |
c64e148a | 466 | local_t entries_bytes; |
e4906eff | 467 | local_t entries; |
884bfe89 SP |
468 | local_t overrun; |
469 | local_t commit_overrun; | |
470 | local_t dropped_events; | |
fa743953 SR |
471 | local_t committing; |
472 | local_t commits; | |
2c2b0a78 | 473 | local_t pages_touched; |
31029a8b | 474 | local_t pages_lost; |
2c2b0a78 | 475 | local_t pages_read; |
03329f99 | 476 | long last_pages_touch; |
2c2b0a78 | 477 | size_t shortest_full; |
77ae365e | 478 | unsigned long read; |
c64e148a | 479 | unsigned long read_bytes; |
10464b4a SRV |
480 | rb_time_t write_stamp; |
481 | rb_time_t before_stamp; | |
8672e494 | 482 | u64 event_stamp[MAX_NEST]; |
7a8e76a3 | 483 | u64 read_stamp; |
2d093282 ZY |
484 | /* pages removed since last reset */ |
485 | unsigned long pages_removed; | |
438ced17 | 486 | /* ring buffer pages to update, > 0 to add, < 0 to remove */ |
9b94a8fb | 487 | long nr_pages_to_update; |
438ced17 | 488 | struct list_head new_pages; /* new pages to add */ |
83f40318 | 489 | struct work_struct update_pages_work; |
05fdd70d | 490 | struct completion update_done; |
15693458 SRRH |
491 | |
492 | struct rb_irq_work irq_work; | |
7a8e76a3 SR |
493 | }; |
494 | ||
13292494 | 495 | struct trace_buffer { |
7a8e76a3 SR |
496 | unsigned flags; |
497 | int cpus; | |
7a8e76a3 | 498 | atomic_t record_disabled; |
8a96c028 | 499 | atomic_t resizing; |
00f62f61 | 500 | cpumask_var_t cpumask; |
7a8e76a3 | 501 | |
1f8a6a10 PZ |
502 | struct lock_class_key *reader_lock_key; |
503 | ||
7a8e76a3 SR |
504 | struct mutex mutex; |
505 | ||
506 | struct ring_buffer_per_cpu **buffers; | |
554f786e | 507 | |
b32614c0 | 508 | struct hlist_node node; |
37886f6a | 509 | u64 (*clock)(void); |
15693458 SRRH |
510 | |
511 | struct rb_irq_work irq_work; | |
00b41452 | 512 | bool time_stamp_abs; |
139f8400 TSV |
513 | |
514 | unsigned int subbuf_size; | |
2808e31e | 515 | unsigned int subbuf_order; |
139f8400 | 516 | unsigned int max_data_size; |
7a8e76a3 SR |
517 | }; |
518 | ||
519 | struct ring_buffer_iter { | |
520 | struct ring_buffer_per_cpu *cpu_buffer; | |
521 | unsigned long head; | |
785888c5 | 522 | unsigned long next_event; |
7a8e76a3 | 523 | struct buffer_page *head_page; |
492a74f4 SR |
524 | struct buffer_page *cache_reader_page; |
525 | unsigned long cache_read; | |
2d093282 | 526 | unsigned long cache_pages_removed; |
7a8e76a3 | 527 | u64 read_stamp; |
28e3fc56 | 528 | u64 page_stamp; |
785888c5 | 529 | struct ring_buffer_event *event; |
139f8400 | 530 | size_t event_size; |
c9b7a4a7 | 531 | int missed_events; |
7a8e76a3 SR |
532 | }; |
533 | ||
139f8400 | 534 | int ring_buffer_print_page_header(struct trace_buffer *buffer, struct trace_seq *s) |
10464b4a | 535 | { |
d5cfbdfc | 536 | struct buffer_data_page field; |
10464b4a | 537 | |
d5cfbdfc TSV |
538 | trace_seq_printf(s, "\tfield: u64 timestamp;\t" |
539 | "offset:0;\tsize:%u;\tsigned:%u;\n", | |
540 | (unsigned int)sizeof(field.time_stamp), | |
541 | (unsigned int)is_signed_type(u64)); | |
10464b4a | 542 | |
d5cfbdfc TSV |
543 | trace_seq_printf(s, "\tfield: local_t commit;\t" |
544 | "offset:%u;\tsize:%u;\tsigned:%u;\n", | |
545 | (unsigned int)offsetof(typeof(field), commit), | |
546 | (unsigned int)sizeof(field.commit), | |
547 | (unsigned int)is_signed_type(long)); | |
10464b4a | 548 | |
d5cfbdfc TSV |
549 | trace_seq_printf(s, "\tfield: int overwrite;\t" |
550 | "offset:%u;\tsize:%u;\tsigned:%u;\n", | |
551 | (unsigned int)offsetof(typeof(field), commit), | |
552 | 1, | |
553 | (unsigned int)is_signed_type(long)); | |
10464b4a | 554 | |
d5cfbdfc TSV |
555 | trace_seq_printf(s, "\tfield: char data;\t" |
556 | "offset:%u;\tsize:%u;\tsigned:%u;\n", | |
557 | (unsigned int)offsetof(typeof(field), data), | |
139f8400 | 558 | (unsigned int)buffer->subbuf_size, |
d5cfbdfc | 559 | (unsigned int)is_signed_type(char)); |
10464b4a | 560 | |
d5cfbdfc | 561 | return !trace_seq_has_overflowed(s); |
10464b4a SRV |
562 | } |
563 | ||
c84897c0 | 564 | static inline void rb_time_read(rb_time_t *t, u64 *ret) |
10464b4a SRV |
565 | { |
566 | *ret = local64_read(&t->time); | |
10464b4a SRV |
567 | } |
568 | static void rb_time_set(rb_time_t *t, u64 val) | |
569 | { | |
570 | local64_set(&t->time, val); | |
571 | } | |
10464b4a | 572 | |
a948c69d SRV |
573 | /* |
574 | * Enable this to make sure that the event passed to | |
575 | * ring_buffer_event_time_stamp() is not committed and also | |
576 | * is on the buffer that it passed in. | |
577 | */ | |
578 | //#define RB_VERIFY_EVENT | |
579 | #ifdef RB_VERIFY_EVENT | |
580 | static struct list_head *rb_list_head(struct list_head *list); | |
581 | static void verify_event(struct ring_buffer_per_cpu *cpu_buffer, | |
582 | void *event) | |
583 | { | |
584 | struct buffer_page *page = cpu_buffer->commit_page; | |
585 | struct buffer_page *tail_page = READ_ONCE(cpu_buffer->tail_page); | |
586 | struct list_head *next; | |
587 | long commit, write; | |
588 | unsigned long addr = (unsigned long)event; | |
589 | bool done = false; | |
590 | int stop = 0; | |
591 | ||
592 | /* Make sure the event exists and is not committed yet */ | |
593 | do { | |
594 | if (page == tail_page || WARN_ON_ONCE(stop++ > 100)) | |
595 | done = true; | |
596 | commit = local_read(&page->page->commit); | |
597 | write = local_read(&page->write); | |
598 | if (addr >= (unsigned long)&page->page->data[commit] && | |
599 | addr < (unsigned long)&page->page->data[write]) | |
600 | return; | |
601 | ||
602 | next = rb_list_head(page->list.next); | |
603 | page = list_entry(next, struct buffer_page, list); | |
604 | } while (!done); | |
605 | WARN_ON_ONCE(1); | |
606 | } | |
607 | #else | |
608 | static inline void verify_event(struct ring_buffer_per_cpu *cpu_buffer, | |
609 | void *event) | |
610 | { | |
611 | } | |
612 | #endif | |
613 | ||
6695da58 SRG |
614 | /* |
615 | * The absolute time stamp drops the 5 MSBs and some clocks may | |
616 | * require them. The rb_fix_abs_ts() will take a previous full | |
617 | * time stamp, and add the 5 MSB of that time stamp on to the | |
618 | * saved absolute time stamp. Then they are compared in case of | |
619 | * the unlikely event that the latest time stamp incremented | |
620 | * the 5 MSB. | |
621 | */ | |
622 | static inline u64 rb_fix_abs_ts(u64 abs, u64 save_ts) | |
623 | { | |
624 | if (save_ts & TS_MSB) { | |
625 | abs |= save_ts & TS_MSB; | |
626 | /* Check for overflow */ | |
627 | if (unlikely(abs < save_ts)) | |
628 | abs += 1ULL << 59; | |
629 | } | |
630 | return abs; | |
631 | } | |
a948c69d | 632 | |
efe6196a SRV |
633 | static inline u64 rb_time_stamp(struct trace_buffer *buffer); |
634 | ||
635 | /** | |
636 | * ring_buffer_event_time_stamp - return the event's current time stamp | |
637 | * @buffer: The buffer that the event is on | |
638 | * @event: the event to get the time stamp of | |
639 | * | |
640 | * Note, this must be called after @event is reserved, and before it is | |
641 | * committed to the ring buffer. And must be called from the same | |
642 | * context where the event was reserved (normal, softirq, irq, etc). | |
643 | * | |
644 | * Returns the time stamp associated with the current event. | |
645 | * If the event has an extended time stamp, then that is used as | |
646 | * the time stamp to return. | |
647 | * In the highly unlikely case that the event was nested more than | |
648 | * the max nesting, then the write_stamp of the buffer is returned, | |
649 | * otherwise current time is returned, but that really neither of | |
650 | * the last two cases should ever happen. | |
651 | */ | |
652 | u64 ring_buffer_event_time_stamp(struct trace_buffer *buffer, | |
653 | struct ring_buffer_event *event) | |
654 | { | |
655 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[smp_processor_id()]; | |
656 | unsigned int nest; | |
657 | u64 ts; | |
658 | ||
659 | /* If the event includes an absolute time, then just use that */ | |
6695da58 SRG |
660 | if (event->type_len == RINGBUF_TYPE_TIME_STAMP) { |
661 | ts = rb_event_time_stamp(event); | |
662 | return rb_fix_abs_ts(ts, cpu_buffer->tail_page->page->time_stamp); | |
663 | } | |
efe6196a | 664 | |
a948c69d SRV |
665 | nest = local_read(&cpu_buffer->committing); |
666 | verify_event(cpu_buffer, event); | |
667 | if (WARN_ON_ONCE(!nest)) | |
668 | goto fail; | |
669 | ||
efe6196a | 670 | /* Read the current saved nesting level time stamp */ |
a948c69d | 671 | if (likely(--nest < MAX_NEST)) |
efe6196a SRV |
672 | return cpu_buffer->event_stamp[nest]; |
673 | ||
a948c69d SRV |
674 | /* Shouldn't happen, warn if it does */ |
675 | WARN_ONCE(1, "nest (%d) greater than max", nest); | |
efe6196a | 676 | |
a948c69d | 677 | fail: |
c84897c0 | 678 | rb_time_read(&cpu_buffer->write_stamp, &ts); |
efe6196a SRV |
679 | |
680 | return ts; | |
681 | } | |
682 | ||
2c2b0a78 SRV |
683 | /** |
684 | * ring_buffer_nr_pages - get the number of buffer pages in the ring buffer | |
685 | * @buffer: The ring_buffer to get the number of pages from | |
686 | * @cpu: The cpu of the ring_buffer to get the number of pages from | |
687 | * | |
688 | * Returns the number of pages used by a per_cpu buffer of the ring buffer. | |
689 | */ | |
13292494 | 690 | size_t ring_buffer_nr_pages(struct trace_buffer *buffer, int cpu) |
2c2b0a78 SRV |
691 | { |
692 | return buffer->buffers[cpu]->nr_pages; | |
693 | } | |
694 | ||
695 | /** | |
b7085b6f | 696 | * ring_buffer_nr_dirty_pages - get the number of used pages in the ring buffer |
2c2b0a78 SRV |
697 | * @buffer: The ring_buffer to get the number of pages from |
698 | * @cpu: The cpu of the ring_buffer to get the number of pages from | |
699 | * | |
700 | * Returns the number of pages that have content in the ring buffer. | |
701 | */ | |
13292494 | 702 | size_t ring_buffer_nr_dirty_pages(struct trace_buffer *buffer, int cpu) |
2c2b0a78 SRV |
703 | { |
704 | size_t read; | |
31029a8b | 705 | size_t lost; |
2c2b0a78 SRV |
706 | size_t cnt; |
707 | ||
708 | read = local_read(&buffer->buffers[cpu]->pages_read); | |
31029a8b | 709 | lost = local_read(&buffer->buffers[cpu]->pages_lost); |
2c2b0a78 | 710 | cnt = local_read(&buffer->buffers[cpu]->pages_touched); |
31029a8b SRG |
711 | |
712 | if (WARN_ON_ONCE(cnt < lost)) | |
713 | return 0; | |
714 | ||
715 | cnt -= lost; | |
716 | ||
2c2b0a78 SRV |
717 | /* The reader can read an empty page, but not more than that */ |
718 | if (cnt < read) { | |
719 | WARN_ON_ONCE(read > cnt + 1); | |
720 | return 0; | |
721 | } | |
722 | ||
723 | return cnt - read; | |
724 | } | |
725 | ||
42fb0a1e SRG |
726 | static __always_inline bool full_hit(struct trace_buffer *buffer, int cpu, int full) |
727 | { | |
728 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
729 | size_t nr_pages; | |
730 | size_t dirty; | |
731 | ||
732 | nr_pages = cpu_buffer->nr_pages; | |
733 | if (!nr_pages || !full) | |
734 | return true; | |
735 | ||
623b1f89 SRG |
736 | /* |
737 | * Add one as dirty will never equal nr_pages, as the sub-buffer | |
738 | * that the writer is on is not counted as dirty. | |
739 | * This is needed if "buffer_percent" is set to 100. | |
740 | */ | |
741 | dirty = ring_buffer_nr_dirty_pages(buffer, cpu) + 1; | |
42fb0a1e | 742 | |
623b1f89 | 743 | return (dirty * 100) >= (full * nr_pages); |
42fb0a1e SRG |
744 | } |
745 | ||
15693458 SRRH |
746 | /* |
747 | * rb_wake_up_waiters - wake up tasks waiting for ring buffer input | |
748 | * | |
749 | * Schedules a delayed work to wake up any task that is blocked on the | |
750 | * ring buffer waiters queue. | |
751 | */ | |
752 | static void rb_wake_up_waiters(struct irq_work *work) | |
753 | { | |
754 | struct rb_irq_work *rbwork = container_of(work, struct rb_irq_work, work); | |
755 | ||
756 | wake_up_all(&rbwork->waiters); | |
ec0bbc5e | 757 | if (rbwork->full_waiters_pending || rbwork->wakeup_full) { |
68282dd9 SRG |
758 | /* Only cpu_buffer sets the above flags */ |
759 | struct ring_buffer_per_cpu *cpu_buffer = | |
760 | container_of(rbwork, struct ring_buffer_per_cpu, irq_work); | |
761 | ||
762 | /* Called from interrupt context */ | |
763 | raw_spin_lock(&cpu_buffer->reader_lock); | |
1e0d6714 | 764 | rbwork->wakeup_full = false; |
ec0bbc5e | 765 | rbwork->full_waiters_pending = false; |
68282dd9 SRG |
766 | |
767 | /* Waking up all waiters, they will reset the shortest full */ | |
768 | cpu_buffer->shortest_full = 0; | |
769 | raw_spin_unlock(&cpu_buffer->reader_lock); | |
770 | ||
1e0d6714 SRRH |
771 | wake_up_all(&rbwork->full_waiters); |
772 | } | |
15693458 SRRH |
773 | } |
774 | ||
7e9fbbb1 SRG |
775 | /** |
776 | * ring_buffer_wake_waiters - wake up any waiters on this ring buffer | |
777 | * @buffer: The ring buffer to wake waiters on | |
151e34d1 | 778 | * @cpu: The CPU buffer to wake waiters on |
7e9fbbb1 SRG |
779 | * |
780 | * In the case of a file that represents a ring buffer is closing, | |
781 | * it is prudent to wake up any waiters that are on this. | |
782 | */ | |
783 | void ring_buffer_wake_waiters(struct trace_buffer *buffer, int cpu) | |
784 | { | |
785 | struct ring_buffer_per_cpu *cpu_buffer; | |
786 | struct rb_irq_work *rbwork; | |
787 | ||
7433632c SRG |
788 | if (!buffer) |
789 | return; | |
790 | ||
7e9fbbb1 SRG |
791 | if (cpu == RING_BUFFER_ALL_CPUS) { |
792 | ||
793 | /* Wake up individual ones too. One level recursion */ | |
794 | for_each_buffer_cpu(buffer, cpu) | |
795 | ring_buffer_wake_waiters(buffer, cpu); | |
796 | ||
797 | rbwork = &buffer->irq_work; | |
798 | } else { | |
7433632c SRG |
799 | if (WARN_ON_ONCE(!buffer->buffers)) |
800 | return; | |
801 | if (WARN_ON_ONCE(cpu >= nr_cpu_ids)) | |
802 | return; | |
803 | ||
7e9fbbb1 | 804 | cpu_buffer = buffer->buffers[cpu]; |
7433632c SRG |
805 | /* The CPU buffer may not have been initialized yet */ |
806 | if (!cpu_buffer) | |
807 | return; | |
7e9fbbb1 SRG |
808 | rbwork = &cpu_buffer->irq_work; |
809 | } | |
810 | ||
39a7dc23 SRG |
811 | /* This can be called in any context */ |
812 | irq_work_queue(&rbwork->work); | |
7e9fbbb1 SRG |
813 | } |
814 | ||
b3594573 SRG |
815 | static bool rb_watermark_hit(struct trace_buffer *buffer, int cpu, int full) |
816 | { | |
817 | struct ring_buffer_per_cpu *cpu_buffer; | |
818 | bool ret = false; | |
819 | ||
820 | /* Reads of all CPUs always waits for any data */ | |
821 | if (cpu == RING_BUFFER_ALL_CPUS) | |
822 | return !ring_buffer_empty(buffer); | |
823 | ||
824 | cpu_buffer = buffer->buffers[cpu]; | |
825 | ||
826 | if (!ring_buffer_empty_cpu(buffer, cpu)) { | |
827 | unsigned long flags; | |
828 | bool pagebusy; | |
829 | ||
830 | if (!full) | |
831 | return true; | |
832 | ||
833 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
834 | pagebusy = cpu_buffer->reader_page == cpu_buffer->commit_page; | |
835 | ret = !pagebusy && full_hit(buffer, cpu, full); | |
836 | ||
837 | if (!cpu_buffer->shortest_full || | |
838 | cpu_buffer->shortest_full > full) | |
839 | cpu_buffer->shortest_full = full; | |
840 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
841 | } | |
842 | return ret; | |
843 | } | |
844 | ||
15693458 SRRH |
845 | /** |
846 | * ring_buffer_wait - wait for input to the ring buffer | |
847 | * @buffer: buffer to wait on | |
848 | * @cpu: the cpu buffer to wait on | |
e1981f75 | 849 | * @full: wait until the percentage of pages are available, if @cpu != RING_BUFFER_ALL_CPUS |
15693458 SRRH |
850 | * |
851 | * If @cpu == RING_BUFFER_ALL_CPUS then the task will wake up as soon | |
852 | * as data is added to any of the @buffer's cpu buffers. Otherwise | |
853 | * it will wait for data to be added to a specific cpu buffer. | |
854 | */ | |
13292494 | 855 | int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full) |
15693458 | 856 | { |
3f649ab7 | 857 | struct ring_buffer_per_cpu *cpu_buffer; |
15693458 SRRH |
858 | DEFINE_WAIT(wait); |
859 | struct rb_irq_work *work; | |
e30f53aa | 860 | int ret = 0; |
15693458 SRRH |
861 | |
862 | /* | |
863 | * Depending on what the caller is waiting for, either any | |
864 | * data in any cpu buffer, or a specific buffer, put the | |
865 | * caller on the appropriate wait queue. | |
866 | */ | |
1e0d6714 | 867 | if (cpu == RING_BUFFER_ALL_CPUS) { |
15693458 | 868 | work = &buffer->irq_work; |
1e0d6714 | 869 | /* Full only makes sense on per cpu reads */ |
2c2b0a78 | 870 | full = 0; |
1e0d6714 | 871 | } else { |
8b8b3683 SRRH |
872 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
873 | return -ENODEV; | |
15693458 SRRH |
874 | cpu_buffer = buffer->buffers[cpu]; |
875 | work = &cpu_buffer->irq_work; | |
876 | } | |
877 | ||
b3594573 SRG |
878 | if (full) |
879 | prepare_to_wait(&work->full_waiters, &wait, TASK_INTERRUPTIBLE); | |
880 | else | |
881 | prepare_to_wait(&work->waiters, &wait, TASK_INTERRUPTIBLE); | |
882 | ||
883 | /* | |
884 | * The events can happen in critical sections where | |
885 | * checking a work queue can cause deadlocks. | |
886 | * After adding a task to the queue, this flag is set | |
887 | * only to notify events to try to wake up the queue | |
888 | * using irq_work. | |
889 | * | |
890 | * We don't clear it even if the buffer is no longer | |
891 | * empty. The flag only causes the next event to run | |
892 | * irq_work to do the work queue wake up. The worse | |
893 | * that can happen if we race with !trace_empty() is that | |
894 | * an event will cause an irq_work to try to wake up | |
895 | * an empty queue. | |
896 | * | |
897 | * There's no reason to protect this flag either, as | |
898 | * the work queue and irq_work logic will do the necessary | |
899 | * synchronization for the wake ups. The only thing | |
900 | * that is necessary is that the wake up happens after | |
901 | * a task has been queued. It's OK for spurious wake ups. | |
902 | */ | |
903 | if (full) | |
904 | work->full_waiters_pending = true; | |
905 | else | |
906 | work->waiters_pending = true; | |
907 | ||
908 | if (rb_watermark_hit(buffer, cpu, full)) | |
909 | goto out; | |
910 | ||
911 | if (signal_pending(current)) { | |
912 | ret = -EINTR; | |
913 | goto out; | |
e30f53aa | 914 | } |
15693458 | 915 | |
b3594573 SRG |
916 | schedule(); |
917 | out: | |
1e0d6714 SRRH |
918 | if (full) |
919 | finish_wait(&work->full_waiters, &wait); | |
920 | else | |
921 | finish_wait(&work->waiters, &wait); | |
e30f53aa | 922 | |
b3594573 SRG |
923 | if (!ret && !rb_watermark_hit(buffer, cpu, full) && signal_pending(current)) |
924 | ret = -EINTR; | |
925 | ||
e30f53aa | 926 | return ret; |
15693458 SRRH |
927 | } |
928 | ||
929 | /** | |
930 | * ring_buffer_poll_wait - poll on buffer input | |
931 | * @buffer: buffer to wait on | |
932 | * @cpu: the cpu buffer to wait on | |
933 | * @filp: the file descriptor | |
934 | * @poll_table: The poll descriptor | |
42fb0a1e | 935 | * @full: wait until the percentage of pages are available, if @cpu != RING_BUFFER_ALL_CPUS |
15693458 SRRH |
936 | * |
937 | * If @cpu == RING_BUFFER_ALL_CPUS then the task will wake up as soon | |
938 | * as data is added to any of the @buffer's cpu buffers. Otherwise | |
939 | * it will wait for data to be added to a specific cpu buffer. | |
940 | * | |
a9a08845 | 941 | * Returns EPOLLIN | EPOLLRDNORM if data exists in the buffers, |
15693458 SRRH |
942 | * zero otherwise. |
943 | */ | |
13292494 | 944 | __poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu, |
42fb0a1e | 945 | struct file *filp, poll_table *poll_table, int full) |
15693458 SRRH |
946 | { |
947 | struct ring_buffer_per_cpu *cpu_buffer; | |
68282dd9 | 948 | struct rb_irq_work *rbwork; |
15693458 | 949 | |
42fb0a1e | 950 | if (cpu == RING_BUFFER_ALL_CPUS) { |
68282dd9 | 951 | rbwork = &buffer->irq_work; |
42fb0a1e SRG |
952 | full = 0; |
953 | } else { | |
6721cb60 | 954 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
66bbea9e | 955 | return EPOLLERR; |
6721cb60 | 956 | |
15693458 | 957 | cpu_buffer = buffer->buffers[cpu]; |
68282dd9 | 958 | rbwork = &cpu_buffer->irq_work; |
15693458 SRRH |
959 | } |
960 | ||
42fb0a1e | 961 | if (full) { |
68282dd9 SRG |
962 | unsigned long flags; |
963 | ||
964 | poll_wait(filp, &rbwork->full_waiters, poll_table); | |
965 | ||
966 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
967 | rbwork->full_waiters_pending = true; | |
1e0cb399 SRG |
968 | if (!cpu_buffer->shortest_full || |
969 | cpu_buffer->shortest_full > full) | |
970 | cpu_buffer->shortest_full = full; | |
68282dd9 | 971 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
42fb0a1e | 972 | } else { |
68282dd9 SRG |
973 | poll_wait(filp, &rbwork->waiters, poll_table); |
974 | rbwork->waiters_pending = true; | |
42fb0a1e SRG |
975 | } |
976 | ||
4ce97dbf JB |
977 | /* |
978 | * There's a tight race between setting the waiters_pending and | |
979 | * checking if the ring buffer is empty. Once the waiters_pending bit | |
980 | * is set, the next event will wake the task up, but we can get stuck | |
981 | * if there's only a single event in. | |
982 | * | |
983 | * FIXME: Ideally, we need a memory barrier on the writer side as well, | |
984 | * but adding a memory barrier to all events will cause too much of a | |
985 | * performance hit in the fast path. We only need a memory barrier when | |
986 | * the buffer goes from empty to having content. But as this race is | |
987 | * extremely small, and it's not a problem if another event comes in, we | |
988 | * will fix it later. | |
989 | */ | |
990 | smp_mb(); | |
15693458 | 991 | |
42fb0a1e SRG |
992 | if (full) |
993 | return full_hit(buffer, cpu, full) ? EPOLLIN | EPOLLRDNORM : 0; | |
994 | ||
15693458 SRRH |
995 | if ((cpu == RING_BUFFER_ALL_CPUS && !ring_buffer_empty(buffer)) || |
996 | (cpu != RING_BUFFER_ALL_CPUS && !ring_buffer_empty_cpu(buffer, cpu))) | |
a9a08845 | 997 | return EPOLLIN | EPOLLRDNORM; |
15693458 SRRH |
998 | return 0; |
999 | } | |
1000 | ||
f536aafc | 1001 | /* buffer may be either ring_buffer or ring_buffer_per_cpu */ |
077c5407 SR |
1002 | #define RB_WARN_ON(b, cond) \ |
1003 | ({ \ | |
1004 | int _____ret = unlikely(cond); \ | |
1005 | if (_____ret) { \ | |
1006 | if (__same_type(*(b), struct ring_buffer_per_cpu)) { \ | |
1007 | struct ring_buffer_per_cpu *__b = \ | |
1008 | (void *)b; \ | |
1009 | atomic_inc(&__b->buffer->record_disabled); \ | |
1010 | } else \ | |
1011 | atomic_inc(&b->record_disabled); \ | |
1012 | WARN_ON(1); \ | |
1013 | } \ | |
1014 | _____ret; \ | |
3e89c7bb | 1015 | }) |
f536aafc | 1016 | |
37886f6a SR |
1017 | /* Up this if you want to test the TIME_EXTENTS and normalization */ |
1018 | #define DEBUG_SHIFT 0 | |
1019 | ||
13292494 | 1020 | static inline u64 rb_time_stamp(struct trace_buffer *buffer) |
88eb0125 | 1021 | { |
bbeba3e5 SRV |
1022 | u64 ts; |
1023 | ||
1024 | /* Skip retpolines :-( */ | |
1025 | if (IS_ENABLED(CONFIG_RETPOLINE) && likely(buffer->clock == trace_clock_local)) | |
1026 | ts = trace_clock_local(); | |
1027 | else | |
1028 | ts = buffer->clock(); | |
1029 | ||
88eb0125 | 1030 | /* shift to debug/test normalization and TIME_EXTENTS */ |
bbeba3e5 | 1031 | return ts << DEBUG_SHIFT; |
88eb0125 SR |
1032 | } |
1033 | ||
f3ef7202 | 1034 | u64 ring_buffer_time_stamp(struct trace_buffer *buffer) |
37886f6a SR |
1035 | { |
1036 | u64 time; | |
1037 | ||
1038 | preempt_disable_notrace(); | |
6d3f1e12 | 1039 | time = rb_time_stamp(buffer); |
d6097c9e | 1040 | preempt_enable_notrace(); |
37886f6a SR |
1041 | |
1042 | return time; | |
1043 | } | |
1044 | EXPORT_SYMBOL_GPL(ring_buffer_time_stamp); | |
1045 | ||
13292494 | 1046 | void ring_buffer_normalize_time_stamp(struct trace_buffer *buffer, |
37886f6a SR |
1047 | int cpu, u64 *ts) |
1048 | { | |
1049 | /* Just stupid testing the normalize function and deltas */ | |
1050 | *ts >>= DEBUG_SHIFT; | |
1051 | } | |
1052 | EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp); | |
1053 | ||
77ae365e SR |
1054 | /* |
1055 | * Making the ring buffer lockless makes things tricky. | |
1056 | * Although writes only happen on the CPU that they are on, | |
1057 | * and they only need to worry about interrupts. Reads can | |
1058 | * happen on any CPU. | |
1059 | * | |
1060 | * The reader page is always off the ring buffer, but when the | |
1061 | * reader finishes with a page, it needs to swap its page with | |
1062 | * a new one from the buffer. The reader needs to take from | |
1063 | * the head (writes go to the tail). But if a writer is in overwrite | |
1064 | * mode and wraps, it must push the head page forward. | |
1065 | * | |
1066 | * Here lies the problem. | |
1067 | * | |
1068 | * The reader must be careful to replace only the head page, and | |
1069 | * not another one. As described at the top of the file in the | |
1070 | * ASCII art, the reader sets its old page to point to the next | |
1071 | * page after head. It then sets the page after head to point to | |
1072 | * the old reader page. But if the writer moves the head page | |
1073 | * during this operation, the reader could end up with the tail. | |
1074 | * | |
1075 | * We use cmpxchg to help prevent this race. We also do something | |
1076 | * special with the page before head. We set the LSB to 1. | |
1077 | * | |
1078 | * When the writer must push the page forward, it will clear the | |
1079 | * bit that points to the head page, move the head, and then set | |
1080 | * the bit that points to the new head page. | |
1081 | * | |
1082 | * We also don't want an interrupt coming in and moving the head | |
1083 | * page on another writer. Thus we use the second LSB to catch | |
1084 | * that too. Thus: | |
1085 | * | |
1086 | * head->list->prev->next bit 1 bit 0 | |
1087 | * ------- ------- | |
1088 | * Normal page 0 0 | |
1089 | * Points to head page 0 1 | |
1090 | * New head page 1 0 | |
1091 | * | |
1092 | * Note we can not trust the prev pointer of the head page, because: | |
1093 | * | |
1094 | * +----+ +-----+ +-----+ | |
1095 | * | |------>| T |---X--->| N | | |
1096 | * | |<------| | | | | |
1097 | * +----+ +-----+ +-----+ | |
1098 | * ^ ^ | | |
1099 | * | +-----+ | | | |
1100 | * +----------| R |----------+ | | |
1101 | * | |<-----------+ | |
1102 | * +-----+ | |
1103 | * | |
1104 | * Key: ---X--> HEAD flag set in pointer | |
1105 | * T Tail page | |
1106 | * R Reader page | |
1107 | * N Next page | |
1108 | * | |
1109 | * (see __rb_reserve_next() to see where this happens) | |
1110 | * | |
1111 | * What the above shows is that the reader just swapped out | |
1112 | * the reader page with a page in the buffer, but before it | |
1113 | * could make the new header point back to the new page added | |
1114 | * it was preempted by a writer. The writer moved forward onto | |
1115 | * the new page added by the reader and is about to move forward | |
1116 | * again. | |
1117 | * | |
1118 | * You can see, it is legitimate for the previous pointer of | |
1119 | * the head (or any page) not to point back to itself. But only | |
6167c205 | 1120 | * temporarily. |
77ae365e SR |
1121 | */ |
1122 | ||
1123 | #define RB_PAGE_NORMAL 0UL | |
1124 | #define RB_PAGE_HEAD 1UL | |
1125 | #define RB_PAGE_UPDATE 2UL | |
1126 | ||
1127 | ||
1128 | #define RB_FLAG_MASK 3UL | |
1129 | ||
1130 | /* PAGE_MOVED is not part of the mask */ | |
1131 | #define RB_PAGE_MOVED 4UL | |
1132 | ||
1133 | /* | |
1134 | * rb_list_head - remove any bit | |
1135 | */ | |
1136 | static struct list_head *rb_list_head(struct list_head *list) | |
1137 | { | |
1138 | unsigned long val = (unsigned long)list; | |
1139 | ||
1140 | return (struct list_head *)(val & ~RB_FLAG_MASK); | |
1141 | } | |
1142 | ||
1143 | /* | |
6d3f1e12 | 1144 | * rb_is_head_page - test if the given page is the head page |
77ae365e SR |
1145 | * |
1146 | * Because the reader may move the head_page pointer, we can | |
1147 | * not trust what the head page is (it may be pointing to | |
1148 | * the reader page). But if the next page is a header page, | |
1149 | * its flags will be non zero. | |
1150 | */ | |
42b16b3f | 1151 | static inline int |
6689bed3 | 1152 | rb_is_head_page(struct buffer_page *page, struct list_head *list) |
77ae365e SR |
1153 | { |
1154 | unsigned long val; | |
1155 | ||
1156 | val = (unsigned long)list->next; | |
1157 | ||
1158 | if ((val & ~RB_FLAG_MASK) != (unsigned long)&page->list) | |
1159 | return RB_PAGE_MOVED; | |
1160 | ||
1161 | return val & RB_FLAG_MASK; | |
1162 | } | |
1163 | ||
1164 | /* | |
1165 | * rb_is_reader_page | |
1166 | * | |
1167 | * The unique thing about the reader page, is that, if the | |
1168 | * writer is ever on it, the previous pointer never points | |
1169 | * back to the reader page. | |
1170 | */ | |
06ca3209 | 1171 | static bool rb_is_reader_page(struct buffer_page *page) |
77ae365e SR |
1172 | { |
1173 | struct list_head *list = page->list.prev; | |
1174 | ||
1175 | return rb_list_head(list->next) != &page->list; | |
1176 | } | |
1177 | ||
1178 | /* | |
1179 | * rb_set_list_to_head - set a list_head to be pointing to head. | |
1180 | */ | |
6689bed3 | 1181 | static void rb_set_list_to_head(struct list_head *list) |
77ae365e SR |
1182 | { |
1183 | unsigned long *ptr; | |
1184 | ||
1185 | ptr = (unsigned long *)&list->next; | |
1186 | *ptr |= RB_PAGE_HEAD; | |
1187 | *ptr &= ~RB_PAGE_UPDATE; | |
1188 | } | |
1189 | ||
1190 | /* | |
1191 | * rb_head_page_activate - sets up head page | |
1192 | */ | |
1193 | static void rb_head_page_activate(struct ring_buffer_per_cpu *cpu_buffer) | |
1194 | { | |
1195 | struct buffer_page *head; | |
1196 | ||
1197 | head = cpu_buffer->head_page; | |
1198 | if (!head) | |
1199 | return; | |
1200 | ||
1201 | /* | |
1202 | * Set the previous list pointer to have the HEAD flag. | |
1203 | */ | |
6689bed3 | 1204 | rb_set_list_to_head(head->list.prev); |
77ae365e SR |
1205 | } |
1206 | ||
1207 | static void rb_list_head_clear(struct list_head *list) | |
1208 | { | |
1209 | unsigned long *ptr = (unsigned long *)&list->next; | |
1210 | ||
1211 | *ptr &= ~RB_FLAG_MASK; | |
1212 | } | |
1213 | ||
1214 | /* | |
6167c205 | 1215 | * rb_head_page_deactivate - clears head page ptr (for free list) |
77ae365e SR |
1216 | */ |
1217 | static void | |
1218 | rb_head_page_deactivate(struct ring_buffer_per_cpu *cpu_buffer) | |
1219 | { | |
1220 | struct list_head *hd; | |
1221 | ||
1222 | /* Go through the whole list and clear any pointers found. */ | |
1223 | rb_list_head_clear(cpu_buffer->pages); | |
1224 | ||
1225 | list_for_each(hd, cpu_buffer->pages) | |
1226 | rb_list_head_clear(hd); | |
1227 | } | |
1228 | ||
1229 | static int rb_head_page_set(struct ring_buffer_per_cpu *cpu_buffer, | |
1230 | struct buffer_page *head, | |
1231 | struct buffer_page *prev, | |
1232 | int old_flag, int new_flag) | |
1233 | { | |
1234 | struct list_head *list; | |
1235 | unsigned long val = (unsigned long)&head->list; | |
1236 | unsigned long ret; | |
1237 | ||
1238 | list = &prev->list; | |
1239 | ||
1240 | val &= ~RB_FLAG_MASK; | |
1241 | ||
08a40816 SR |
1242 | ret = cmpxchg((unsigned long *)&list->next, |
1243 | val | old_flag, val | new_flag); | |
77ae365e SR |
1244 | |
1245 | /* check if the reader took the page */ | |
1246 | if ((ret & ~RB_FLAG_MASK) != val) | |
1247 | return RB_PAGE_MOVED; | |
1248 | ||
1249 | return ret & RB_FLAG_MASK; | |
1250 | } | |
1251 | ||
1252 | static int rb_head_page_set_update(struct ring_buffer_per_cpu *cpu_buffer, | |
1253 | struct buffer_page *head, | |
1254 | struct buffer_page *prev, | |
1255 | int old_flag) | |
1256 | { | |
1257 | return rb_head_page_set(cpu_buffer, head, prev, | |
1258 | old_flag, RB_PAGE_UPDATE); | |
1259 | } | |
1260 | ||
1261 | static int rb_head_page_set_head(struct ring_buffer_per_cpu *cpu_buffer, | |
1262 | struct buffer_page *head, | |
1263 | struct buffer_page *prev, | |
1264 | int old_flag) | |
1265 | { | |
1266 | return rb_head_page_set(cpu_buffer, head, prev, | |
1267 | old_flag, RB_PAGE_HEAD); | |
1268 | } | |
1269 | ||
1270 | static int rb_head_page_set_normal(struct ring_buffer_per_cpu *cpu_buffer, | |
1271 | struct buffer_page *head, | |
1272 | struct buffer_page *prev, | |
1273 | int old_flag) | |
1274 | { | |
1275 | return rb_head_page_set(cpu_buffer, head, prev, | |
1276 | old_flag, RB_PAGE_NORMAL); | |
1277 | } | |
1278 | ||
6689bed3 | 1279 | static inline void rb_inc_page(struct buffer_page **bpage) |
77ae365e SR |
1280 | { |
1281 | struct list_head *p = rb_list_head((*bpage)->list.next); | |
1282 | ||
1283 | *bpage = list_entry(p, struct buffer_page, list); | |
1284 | } | |
1285 | ||
1286 | static struct buffer_page * | |
1287 | rb_set_head_page(struct ring_buffer_per_cpu *cpu_buffer) | |
1288 | { | |
1289 | struct buffer_page *head; | |
1290 | struct buffer_page *page; | |
1291 | struct list_head *list; | |
1292 | int i; | |
1293 | ||
1294 | if (RB_WARN_ON(cpu_buffer, !cpu_buffer->head_page)) | |
1295 | return NULL; | |
1296 | ||
1297 | /* sanity check */ | |
1298 | list = cpu_buffer->pages; | |
1299 | if (RB_WARN_ON(cpu_buffer, rb_list_head(list->prev->next) != list)) | |
1300 | return NULL; | |
1301 | ||
1302 | page = head = cpu_buffer->head_page; | |
1303 | /* | |
1304 | * It is possible that the writer moves the header behind | |
1305 | * where we started, and we miss in one loop. | |
1306 | * A second loop should grab the header, but we'll do | |
1307 | * three loops just because I'm paranoid. | |
1308 | */ | |
1309 | for (i = 0; i < 3; i++) { | |
1310 | do { | |
6689bed3 | 1311 | if (rb_is_head_page(page, page->list.prev)) { |
77ae365e SR |
1312 | cpu_buffer->head_page = page; |
1313 | return page; | |
1314 | } | |
6689bed3 | 1315 | rb_inc_page(&page); |
77ae365e SR |
1316 | } while (page != head); |
1317 | } | |
1318 | ||
1319 | RB_WARN_ON(cpu_buffer, 1); | |
1320 | ||
1321 | return NULL; | |
1322 | } | |
1323 | ||
bc92b956 | 1324 | static bool rb_head_page_replace(struct buffer_page *old, |
77ae365e SR |
1325 | struct buffer_page *new) |
1326 | { | |
1327 | unsigned long *ptr = (unsigned long *)&old->list.prev->next; | |
1328 | unsigned long val; | |
77ae365e SR |
1329 | |
1330 | val = *ptr & ~RB_FLAG_MASK; | |
1331 | val |= RB_PAGE_HEAD; | |
1332 | ||
00a8478f | 1333 | return try_cmpxchg(ptr, &val, (unsigned long)&new->list); |
77ae365e SR |
1334 | } |
1335 | ||
1336 | /* | |
1337 | * rb_tail_page_update - move the tail page forward | |
77ae365e | 1338 | */ |
70004986 | 1339 | static void rb_tail_page_update(struct ring_buffer_per_cpu *cpu_buffer, |
77ae365e SR |
1340 | struct buffer_page *tail_page, |
1341 | struct buffer_page *next_page) | |
1342 | { | |
77ae365e SR |
1343 | unsigned long old_entries; |
1344 | unsigned long old_write; | |
77ae365e SR |
1345 | |
1346 | /* | |
1347 | * The tail page now needs to be moved forward. | |
1348 | * | |
1349 | * We need to reset the tail page, but without messing | |
1350 | * with possible erasing of data brought in by interrupts | |
1351 | * that have moved the tail page and are currently on it. | |
1352 | * | |
1353 | * We add a counter to the write field to denote this. | |
1354 | */ | |
1355 | old_write = local_add_return(RB_WRITE_INTCNT, &next_page->write); | |
1356 | old_entries = local_add_return(RB_WRITE_INTCNT, &next_page->entries); | |
1357 | ||
2c2b0a78 | 1358 | local_inc(&cpu_buffer->pages_touched); |
77ae365e SR |
1359 | /* |
1360 | * Just make sure we have seen our old_write and synchronize | |
1361 | * with any interrupts that come in. | |
1362 | */ | |
1363 | barrier(); | |
1364 | ||
1365 | /* | |
1366 | * If the tail page is still the same as what we think | |
1367 | * it is, then it is up to us to update the tail | |
1368 | * pointer. | |
1369 | */ | |
8573636e | 1370 | if (tail_page == READ_ONCE(cpu_buffer->tail_page)) { |
77ae365e SR |
1371 | /* Zero the write counter */ |
1372 | unsigned long val = old_write & ~RB_WRITE_MASK; | |
1373 | unsigned long eval = old_entries & ~RB_WRITE_MASK; | |
1374 | ||
1375 | /* | |
1376 | * This will only succeed if an interrupt did | |
1377 | * not come in and change it. In which case, we | |
1378 | * do not want to modify it. | |
da706d8b LJ |
1379 | * |
1380 | * We add (void) to let the compiler know that we do not care | |
1381 | * about the return value of these functions. We use the | |
1382 | * cmpxchg to only update if an interrupt did not already | |
1383 | * do it for us. If the cmpxchg fails, we don't care. | |
77ae365e | 1384 | */ |
da706d8b LJ |
1385 | (void)local_cmpxchg(&next_page->write, old_write, val); |
1386 | (void)local_cmpxchg(&next_page->entries, old_entries, eval); | |
77ae365e SR |
1387 | |
1388 | /* | |
1389 | * No need to worry about races with clearing out the commit. | |
1390 | * it only can increment when a commit takes place. But that | |
1391 | * only happens in the outer most nested commit. | |
1392 | */ | |
1393 | local_set(&next_page->page->commit, 0); | |
1394 | ||
70004986 SRRH |
1395 | /* Again, either we update tail_page or an interrupt does */ |
1396 | (void)cmpxchg(&cpu_buffer->tail_page, tail_page, next_page); | |
77ae365e | 1397 | } |
77ae365e SR |
1398 | } |
1399 | ||
b4b55dfd | 1400 | static void rb_check_bpage(struct ring_buffer_per_cpu *cpu_buffer, |
77ae365e SR |
1401 | struct buffer_page *bpage) |
1402 | { | |
1403 | unsigned long val = (unsigned long)bpage; | |
1404 | ||
b4b55dfd | 1405 | RB_WARN_ON(cpu_buffer, val & RB_FLAG_MASK); |
77ae365e SR |
1406 | } |
1407 | ||
7a8e76a3 | 1408 | /** |
d611851b | 1409 | * rb_check_pages - integrity check of buffer pages |
7a8e76a3 SR |
1410 | * @cpu_buffer: CPU buffer with pages to test |
1411 | * | |
c3706f00 | 1412 | * As a safety measure we check to make sure the data pages have not |
7a8e76a3 SR |
1413 | * been corrupted. |
1414 | */ | |
b4b55dfd | 1415 | static void rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 1416 | { |
8843e06f MO |
1417 | struct list_head *head = rb_list_head(cpu_buffer->pages); |
1418 | struct list_head *tmp; | |
308f7eeb | 1419 | |
8843e06f MO |
1420 | if (RB_WARN_ON(cpu_buffer, |
1421 | rb_list_head(rb_list_head(head->next)->prev) != head)) | |
b4b55dfd | 1422 | return; |
7a8e76a3 | 1423 | |
8843e06f MO |
1424 | if (RB_WARN_ON(cpu_buffer, |
1425 | rb_list_head(rb_list_head(head->prev)->next) != head)) | |
b4b55dfd | 1426 | return; |
77ae365e | 1427 | |
8843e06f | 1428 | for (tmp = rb_list_head(head->next); tmp != head; tmp = rb_list_head(tmp->next)) { |
3e89c7bb | 1429 | if (RB_WARN_ON(cpu_buffer, |
8843e06f | 1430 | rb_list_head(rb_list_head(tmp->next)->prev) != tmp)) |
b4b55dfd | 1431 | return; |
8843e06f | 1432 | |
3e89c7bb | 1433 | if (RB_WARN_ON(cpu_buffer, |
8843e06f | 1434 | rb_list_head(rb_list_head(tmp->prev)->next) != tmp)) |
b4b55dfd | 1435 | return; |
7a8e76a3 | 1436 | } |
7a8e76a3 SR |
1437 | } |
1438 | ||
74e2afc6 QH |
1439 | static int __rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, |
1440 | long nr_pages, struct list_head *pages) | |
7a8e76a3 | 1441 | { |
044fa782 | 1442 | struct buffer_page *bpage, *tmp; |
927e56db SRV |
1443 | bool user_thread = current->mm != NULL; |
1444 | gfp_t mflags; | |
9b94a8fb | 1445 | long i; |
3adc54fa | 1446 | |
927e56db SRV |
1447 | /* |
1448 | * Check if the available memory is there first. | |
1449 | * Note, si_mem_available() only gives us a rough estimate of available | |
1450 | * memory. It may not be accurate. But we don't care, we just want | |
1451 | * to prevent doing any allocation when it is obvious that it is | |
1452 | * not going to succeed. | |
1453 | */ | |
2a872fa4 SRV |
1454 | i = si_mem_available(); |
1455 | if (i < nr_pages) | |
1456 | return -ENOMEM; | |
1457 | ||
927e56db SRV |
1458 | /* |
1459 | * __GFP_RETRY_MAYFAIL flag makes sure that the allocation fails | |
1460 | * gracefully without invoking oom-killer and the system is not | |
1461 | * destabilized. | |
1462 | */ | |
1463 | mflags = GFP_KERNEL | __GFP_RETRY_MAYFAIL; | |
1464 | ||
1465 | /* | |
1466 | * If a user thread allocates too much, and si_mem_available() | |
1467 | * reports there's enough memory, even though there is not. | |
1468 | * Make sure the OOM killer kills this thread. This can happen | |
1469 | * even with RETRY_MAYFAIL because another task may be doing | |
1470 | * an allocation after this task has taken all memory. | |
1471 | * This is the task the OOM killer needs to take out during this | |
1472 | * loop, even if it was triggered by an allocation somewhere else. | |
1473 | */ | |
1474 | if (user_thread) | |
1475 | set_current_oom_origin(); | |
7a8e76a3 | 1476 | for (i = 0; i < nr_pages; i++) { |
7ea59064 | 1477 | struct page *page; |
927e56db | 1478 | |
044fa782 | 1479 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
74e2afc6 | 1480 | mflags, cpu_to_node(cpu_buffer->cpu)); |
044fa782 | 1481 | if (!bpage) |
e4c2ce82 | 1482 | goto free_pages; |
77ae365e | 1483 | |
74e2afc6 QH |
1484 | rb_check_bpage(cpu_buffer, bpage); |
1485 | ||
438ced17 | 1486 | list_add(&bpage->list, pages); |
77ae365e | 1487 | |
f9b94daa TSV |
1488 | page = alloc_pages_node(cpu_to_node(cpu_buffer->cpu), mflags, |
1489 | cpu_buffer->buffer->subbuf_order); | |
7ea59064 | 1490 | if (!page) |
7a8e76a3 | 1491 | goto free_pages; |
7ea59064 | 1492 | bpage->page = page_address(page); |
f9b94daa | 1493 | bpage->order = cpu_buffer->buffer->subbuf_order; |
044fa782 | 1494 | rb_init_page(bpage->page); |
927e56db SRV |
1495 | |
1496 | if (user_thread && fatal_signal_pending(current)) | |
1497 | goto free_pages; | |
7a8e76a3 | 1498 | } |
927e56db SRV |
1499 | if (user_thread) |
1500 | clear_current_oom_origin(); | |
7a8e76a3 | 1501 | |
438ced17 VN |
1502 | return 0; |
1503 | ||
1504 | free_pages: | |
1505 | list_for_each_entry_safe(bpage, tmp, pages, list) { | |
1506 | list_del_init(&bpage->list); | |
1507 | free_buffer_page(bpage); | |
1508 | } | |
927e56db SRV |
1509 | if (user_thread) |
1510 | clear_current_oom_origin(); | |
438ced17 VN |
1511 | |
1512 | return -ENOMEM; | |
1513 | } | |
1514 | ||
1515 | static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, | |
9b94a8fb | 1516 | unsigned long nr_pages) |
438ced17 VN |
1517 | { |
1518 | LIST_HEAD(pages); | |
1519 | ||
1520 | WARN_ON(!nr_pages); | |
1521 | ||
74e2afc6 | 1522 | if (__rb_allocate_pages(cpu_buffer, nr_pages, &pages)) |
438ced17 VN |
1523 | return -ENOMEM; |
1524 | ||
3adc54fa SR |
1525 | /* |
1526 | * The ring buffer page list is a circular list that does not | |
1527 | * start and end with a list head. All page list items point to | |
1528 | * other pages. | |
1529 | */ | |
1530 | cpu_buffer->pages = pages.next; | |
1531 | list_del(&pages); | |
7a8e76a3 | 1532 | |
438ced17 VN |
1533 | cpu_buffer->nr_pages = nr_pages; |
1534 | ||
7a8e76a3 SR |
1535 | rb_check_pages(cpu_buffer); |
1536 | ||
1537 | return 0; | |
7a8e76a3 SR |
1538 | } |
1539 | ||
1540 | static struct ring_buffer_per_cpu * | |
13292494 | 1541 | rb_allocate_cpu_buffer(struct trace_buffer *buffer, long nr_pages, int cpu) |
7a8e76a3 SR |
1542 | { |
1543 | struct ring_buffer_per_cpu *cpu_buffer; | |
044fa782 | 1544 | struct buffer_page *bpage; |
7ea59064 | 1545 | struct page *page; |
7a8e76a3 SR |
1546 | int ret; |
1547 | ||
1548 | cpu_buffer = kzalloc_node(ALIGN(sizeof(*cpu_buffer), cache_line_size()), | |
1549 | GFP_KERNEL, cpu_to_node(cpu)); | |
1550 | if (!cpu_buffer) | |
1551 | return NULL; | |
1552 | ||
1553 | cpu_buffer->cpu = cpu; | |
1554 | cpu_buffer->buffer = buffer; | |
5389f6fa | 1555 | raw_spin_lock_init(&cpu_buffer->reader_lock); |
1f8a6a10 | 1556 | lockdep_set_class(&cpu_buffer->reader_lock, buffer->reader_lock_key); |
edc35bd7 | 1557 | cpu_buffer->lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; |
83f40318 | 1558 | INIT_WORK(&cpu_buffer->update_pages_work, update_pages_handler); |
05fdd70d | 1559 | init_completion(&cpu_buffer->update_done); |
15693458 | 1560 | init_irq_work(&cpu_buffer->irq_work.work, rb_wake_up_waiters); |
f1dc6725 | 1561 | init_waitqueue_head(&cpu_buffer->irq_work.waiters); |
1e0d6714 | 1562 | init_waitqueue_head(&cpu_buffer->irq_work.full_waiters); |
7a8e76a3 | 1563 | |
044fa782 | 1564 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
e4c2ce82 | 1565 | GFP_KERNEL, cpu_to_node(cpu)); |
044fa782 | 1566 | if (!bpage) |
e4c2ce82 SR |
1567 | goto fail_free_buffer; |
1568 | ||
77ae365e SR |
1569 | rb_check_bpage(cpu_buffer, bpage); |
1570 | ||
044fa782 | 1571 | cpu_buffer->reader_page = bpage; |
f9b94daa TSV |
1572 | |
1573 | page = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL, cpu_buffer->buffer->subbuf_order); | |
7ea59064 | 1574 | if (!page) |
e4c2ce82 | 1575 | goto fail_free_reader; |
7ea59064 | 1576 | bpage->page = page_address(page); |
044fa782 | 1577 | rb_init_page(bpage->page); |
e4c2ce82 | 1578 | |
d769041f | 1579 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); |
44b99462 | 1580 | INIT_LIST_HEAD(&cpu_buffer->new_pages); |
d769041f | 1581 | |
438ced17 | 1582 | ret = rb_allocate_pages(cpu_buffer, nr_pages); |
7a8e76a3 | 1583 | if (ret < 0) |
d769041f | 1584 | goto fail_free_reader; |
7a8e76a3 SR |
1585 | |
1586 | cpu_buffer->head_page | |
3adc54fa | 1587 | = list_entry(cpu_buffer->pages, struct buffer_page, list); |
bf41a158 | 1588 | cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; |
7a8e76a3 | 1589 | |
77ae365e SR |
1590 | rb_head_page_activate(cpu_buffer); |
1591 | ||
7a8e76a3 SR |
1592 | return cpu_buffer; |
1593 | ||
d769041f SR |
1594 | fail_free_reader: |
1595 | free_buffer_page(cpu_buffer->reader_page); | |
1596 | ||
7a8e76a3 SR |
1597 | fail_free_buffer: |
1598 | kfree(cpu_buffer); | |
1599 | return NULL; | |
1600 | } | |
1601 | ||
1602 | static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) | |
1603 | { | |
3adc54fa | 1604 | struct list_head *head = cpu_buffer->pages; |
044fa782 | 1605 | struct buffer_page *bpage, *tmp; |
7a8e76a3 | 1606 | |
675751bb JB |
1607 | irq_work_sync(&cpu_buffer->irq_work.work); |
1608 | ||
d769041f SR |
1609 | free_buffer_page(cpu_buffer->reader_page); |
1610 | ||
3adc54fa | 1611 | if (head) { |
56f4ca0a DT |
1612 | rb_head_page_deactivate(cpu_buffer); |
1613 | ||
3adc54fa SR |
1614 | list_for_each_entry_safe(bpage, tmp, head, list) { |
1615 | list_del_init(&bpage->list); | |
1616 | free_buffer_page(bpage); | |
1617 | } | |
1618 | bpage = list_entry(head, struct buffer_page, list); | |
044fa782 | 1619 | free_buffer_page(bpage); |
7a8e76a3 | 1620 | } |
3adc54fa | 1621 | |
17d80175 SRG |
1622 | free_page((unsigned long)cpu_buffer->free_page); |
1623 | ||
7a8e76a3 SR |
1624 | kfree(cpu_buffer); |
1625 | } | |
1626 | ||
1627 | /** | |
d611851b | 1628 | * __ring_buffer_alloc - allocate a new ring_buffer |
68814b58 | 1629 | * @size: the size in bytes per cpu that is needed. |
7a8e76a3 | 1630 | * @flags: attributes to set for the ring buffer. |
59e7cffe | 1631 | * @key: ring buffer reader_lock_key. |
7a8e76a3 SR |
1632 | * |
1633 | * Currently the only flag that is available is the RB_FL_OVERWRITE | |
1634 | * flag. This flag means that the buffer will overwrite old data | |
1635 | * when the buffer wraps. If this flag is not set, the buffer will | |
1636 | * drop data when the tail hits the head. | |
1637 | */ | |
13292494 | 1638 | struct trace_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, |
1f8a6a10 | 1639 | struct lock_class_key *key) |
7a8e76a3 | 1640 | { |
13292494 | 1641 | struct trace_buffer *buffer; |
9b94a8fb | 1642 | long nr_pages; |
7a8e76a3 | 1643 | int bsize; |
9b94a8fb | 1644 | int cpu; |
b32614c0 | 1645 | int ret; |
7a8e76a3 SR |
1646 | |
1647 | /* keep it in its own cache line */ | |
1648 | buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()), | |
1649 | GFP_KERNEL); | |
1650 | if (!buffer) | |
1651 | return NULL; | |
1652 | ||
b18cc3de | 1653 | if (!zalloc_cpumask_var(&buffer->cpumask, GFP_KERNEL)) |
9e01c1b7 RR |
1654 | goto fail_free_buffer; |
1655 | ||
139f8400 | 1656 | /* Default buffer page size - one system page */ |
f9b94daa | 1657 | buffer->subbuf_order = 0; |
139f8400 TSV |
1658 | buffer->subbuf_size = PAGE_SIZE - BUF_PAGE_HDR_SIZE; |
1659 | ||
1660 | /* Max payload is buffer page size - header (8bytes) */ | |
1661 | buffer->max_data_size = buffer->subbuf_size - (sizeof(u32) * 2); | |
1662 | ||
1663 | nr_pages = DIV_ROUND_UP(size, buffer->subbuf_size); | |
7a8e76a3 | 1664 | buffer->flags = flags; |
37886f6a | 1665 | buffer->clock = trace_clock_local; |
1f8a6a10 | 1666 | buffer->reader_lock_key = key; |
7a8e76a3 | 1667 | |
15693458 | 1668 | init_irq_work(&buffer->irq_work.work, rb_wake_up_waiters); |
f1dc6725 | 1669 | init_waitqueue_head(&buffer->irq_work.waiters); |
15693458 | 1670 | |
7a8e76a3 | 1671 | /* need at least two pages */ |
438ced17 VN |
1672 | if (nr_pages < 2) |
1673 | nr_pages = 2; | |
7a8e76a3 | 1674 | |
7a8e76a3 SR |
1675 | buffer->cpus = nr_cpu_ids; |
1676 | ||
1677 | bsize = sizeof(void *) * nr_cpu_ids; | |
1678 | buffer->buffers = kzalloc(ALIGN(bsize, cache_line_size()), | |
1679 | GFP_KERNEL); | |
1680 | if (!buffer->buffers) | |
9e01c1b7 | 1681 | goto fail_free_cpumask; |
7a8e76a3 | 1682 | |
b32614c0 SAS |
1683 | cpu = raw_smp_processor_id(); |
1684 | cpumask_set_cpu(cpu, buffer->cpumask); | |
1685 | buffer->buffers[cpu] = rb_allocate_cpu_buffer(buffer, nr_pages, cpu); | |
1686 | if (!buffer->buffers[cpu]) | |
1687 | goto fail_free_buffers; | |
7a8e76a3 | 1688 | |
b32614c0 SAS |
1689 | ret = cpuhp_state_add_instance(CPUHP_TRACE_RB_PREPARE, &buffer->node); |
1690 | if (ret < 0) | |
1691 | goto fail_free_buffers; | |
554f786e | 1692 | |
7a8e76a3 SR |
1693 | mutex_init(&buffer->mutex); |
1694 | ||
1695 | return buffer; | |
1696 | ||
1697 | fail_free_buffers: | |
1698 | for_each_buffer_cpu(buffer, cpu) { | |
1699 | if (buffer->buffers[cpu]) | |
1700 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
1701 | } | |
1702 | kfree(buffer->buffers); | |
1703 | ||
9e01c1b7 RR |
1704 | fail_free_cpumask: |
1705 | free_cpumask_var(buffer->cpumask); | |
1706 | ||
7a8e76a3 SR |
1707 | fail_free_buffer: |
1708 | kfree(buffer); | |
1709 | return NULL; | |
1710 | } | |
1f8a6a10 | 1711 | EXPORT_SYMBOL_GPL(__ring_buffer_alloc); |
7a8e76a3 SR |
1712 | |
1713 | /** | |
1714 | * ring_buffer_free - free a ring buffer. | |
1715 | * @buffer: the buffer to free. | |
1716 | */ | |
1717 | void | |
13292494 | 1718 | ring_buffer_free(struct trace_buffer *buffer) |
7a8e76a3 SR |
1719 | { |
1720 | int cpu; | |
1721 | ||
b32614c0 | 1722 | cpuhp_state_remove_instance(CPUHP_TRACE_RB_PREPARE, &buffer->node); |
554f786e | 1723 | |
675751bb JB |
1724 | irq_work_sync(&buffer->irq_work.work); |
1725 | ||
7a8e76a3 SR |
1726 | for_each_buffer_cpu(buffer, cpu) |
1727 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
1728 | ||
bd3f0221 | 1729 | kfree(buffer->buffers); |
9e01c1b7 RR |
1730 | free_cpumask_var(buffer->cpumask); |
1731 | ||
7a8e76a3 SR |
1732 | kfree(buffer); |
1733 | } | |
c4f50183 | 1734 | EXPORT_SYMBOL_GPL(ring_buffer_free); |
7a8e76a3 | 1735 | |
13292494 | 1736 | void ring_buffer_set_clock(struct trace_buffer *buffer, |
37886f6a SR |
1737 | u64 (*clock)(void)) |
1738 | { | |
1739 | buffer->clock = clock; | |
1740 | } | |
1741 | ||
13292494 | 1742 | void ring_buffer_set_time_stamp_abs(struct trace_buffer *buffer, bool abs) |
00b41452 TZ |
1743 | { |
1744 | buffer->time_stamp_abs = abs; | |
1745 | } | |
1746 | ||
13292494 | 1747 | bool ring_buffer_time_stamp_abs(struct trace_buffer *buffer) |
00b41452 TZ |
1748 | { |
1749 | return buffer->time_stamp_abs; | |
1750 | } | |
1751 | ||
7a8e76a3 SR |
1752 | static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer); |
1753 | ||
83f40318 VN |
1754 | static inline unsigned long rb_page_entries(struct buffer_page *bpage) |
1755 | { | |
1756 | return local_read(&bpage->entries) & RB_WRITE_MASK; | |
1757 | } | |
1758 | ||
1759 | static inline unsigned long rb_page_write(struct buffer_page *bpage) | |
1760 | { | |
1761 | return local_read(&bpage->write) & RB_WRITE_MASK; | |
1762 | } | |
1763 | ||
bc92b956 | 1764 | static bool |
9b94a8fb | 1765 | rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned long nr_pages) |
7a8e76a3 | 1766 | { |
83f40318 VN |
1767 | struct list_head *tail_page, *to_remove, *next_page; |
1768 | struct buffer_page *to_remove_page, *tmp_iter_page; | |
1769 | struct buffer_page *last_page, *first_page; | |
9b94a8fb | 1770 | unsigned long nr_removed; |
83f40318 VN |
1771 | unsigned long head_bit; |
1772 | int page_entries; | |
1773 | ||
1774 | head_bit = 0; | |
7a8e76a3 | 1775 | |
5389f6fa | 1776 | raw_spin_lock_irq(&cpu_buffer->reader_lock); |
83f40318 VN |
1777 | atomic_inc(&cpu_buffer->record_disabled); |
1778 | /* | |
1779 | * We don't race with the readers since we have acquired the reader | |
1780 | * lock. We also don't race with writers after disabling recording. | |
1781 | * This makes it easy to figure out the first and the last page to be | |
1782 | * removed from the list. We unlink all the pages in between including | |
1783 | * the first and last pages. This is done in a busy loop so that we | |
1784 | * lose the least number of traces. | |
1785 | * The pages are freed after we restart recording and unlock readers. | |
1786 | */ | |
1787 | tail_page = &cpu_buffer->tail_page->list; | |
77ae365e | 1788 | |
83f40318 VN |
1789 | /* |
1790 | * tail page might be on reader page, we remove the next page | |
1791 | * from the ring buffer | |
1792 | */ | |
1793 | if (cpu_buffer->tail_page == cpu_buffer->reader_page) | |
1794 | tail_page = rb_list_head(tail_page->next); | |
1795 | to_remove = tail_page; | |
1796 | ||
1797 | /* start of pages to remove */ | |
1798 | first_page = list_entry(rb_list_head(to_remove->next), | |
1799 | struct buffer_page, list); | |
1800 | ||
1801 | for (nr_removed = 0; nr_removed < nr_pages; nr_removed++) { | |
1802 | to_remove = rb_list_head(to_remove)->next; | |
1803 | head_bit |= (unsigned long)to_remove & RB_PAGE_HEAD; | |
7a8e76a3 | 1804 | } |
2d093282 ZY |
1805 | /* Read iterators need to reset themselves when some pages removed */ |
1806 | cpu_buffer->pages_removed += nr_removed; | |
7a8e76a3 | 1807 | |
83f40318 | 1808 | next_page = rb_list_head(to_remove)->next; |
7a8e76a3 | 1809 | |
83f40318 VN |
1810 | /* |
1811 | * Now we remove all pages between tail_page and next_page. | |
1812 | * Make sure that we have head_bit value preserved for the | |
1813 | * next page | |
1814 | */ | |
1815 | tail_page->next = (struct list_head *)((unsigned long)next_page | | |
1816 | head_bit); | |
1817 | next_page = rb_list_head(next_page); | |
1818 | next_page->prev = tail_page; | |
1819 | ||
1820 | /* make sure pages points to a valid page in the ring buffer */ | |
1821 | cpu_buffer->pages = next_page; | |
1822 | ||
1823 | /* update head page */ | |
1824 | if (head_bit) | |
1825 | cpu_buffer->head_page = list_entry(next_page, | |
1826 | struct buffer_page, list); | |
1827 | ||
83f40318 VN |
1828 | /* pages are removed, resume tracing and then free the pages */ |
1829 | atomic_dec(&cpu_buffer->record_disabled); | |
5389f6fa | 1830 | raw_spin_unlock_irq(&cpu_buffer->reader_lock); |
83f40318 VN |
1831 | |
1832 | RB_WARN_ON(cpu_buffer, list_empty(cpu_buffer->pages)); | |
1833 | ||
1834 | /* last buffer page to remove */ | |
1835 | last_page = list_entry(rb_list_head(to_remove), struct buffer_page, | |
1836 | list); | |
1837 | tmp_iter_page = first_page; | |
1838 | ||
1839 | do { | |
83f36555 VN |
1840 | cond_resched(); |
1841 | ||
83f40318 | 1842 | to_remove_page = tmp_iter_page; |
6689bed3 | 1843 | rb_inc_page(&tmp_iter_page); |
83f40318 VN |
1844 | |
1845 | /* update the counters */ | |
1846 | page_entries = rb_page_entries(to_remove_page); | |
1847 | if (page_entries) { | |
1848 | /* | |
1849 | * If something was added to this page, it was full | |
1850 | * since it is not the tail page. So we deduct the | |
1851 | * bytes consumed in ring buffer from here. | |
48fdc72f | 1852 | * Increment overrun to account for the lost events. |
83f40318 | 1853 | */ |
48fdc72f | 1854 | local_add(page_entries, &cpu_buffer->overrun); |
45d99ea4 | 1855 | local_sub(rb_page_commit(to_remove_page), &cpu_buffer->entries_bytes); |
31029a8b | 1856 | local_inc(&cpu_buffer->pages_lost); |
83f40318 VN |
1857 | } |
1858 | ||
1859 | /* | |
1860 | * We have already removed references to this list item, just | |
1861 | * free up the buffer_page and its page | |
1862 | */ | |
1863 | free_buffer_page(to_remove_page); | |
1864 | nr_removed--; | |
1865 | ||
1866 | } while (to_remove_page != last_page); | |
1867 | ||
1868 | RB_WARN_ON(cpu_buffer, nr_removed); | |
5040b4b7 VN |
1869 | |
1870 | return nr_removed == 0; | |
7a8e76a3 SR |
1871 | } |
1872 | ||
bc92b956 | 1873 | static bool |
5040b4b7 | 1874 | rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 1875 | { |
5040b4b7 | 1876 | struct list_head *pages = &cpu_buffer->new_pages; |
88ca6a71 | 1877 | unsigned long flags; |
bc92b956 UB |
1878 | bool success; |
1879 | int retries; | |
7a8e76a3 | 1880 | |
88ca6a71 SR |
1881 | /* Can be called at early boot up, where interrupts must not been enabled */ |
1882 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
5040b4b7 VN |
1883 | /* |
1884 | * We are holding the reader lock, so the reader page won't be swapped | |
1885 | * in the ring buffer. Now we are racing with the writer trying to | |
1886 | * move head page and the tail page. | |
1887 | * We are going to adapt the reader page update process where: | |
1888 | * 1. We first splice the start and end of list of new pages between | |
1889 | * the head page and its previous page. | |
1890 | * 2. We cmpxchg the prev_page->next to point from head page to the | |
1891 | * start of new pages list. | |
1892 | * 3. Finally, we update the head->prev to the end of new list. | |
1893 | * | |
1894 | * We will try this process 10 times, to make sure that we don't keep | |
1895 | * spinning. | |
1896 | */ | |
1897 | retries = 10; | |
bc92b956 | 1898 | success = false; |
5040b4b7 | 1899 | while (retries--) { |
bdf4fb62 | 1900 | struct list_head *head_page, *prev_page; |
5040b4b7 VN |
1901 | struct list_head *last_page, *first_page; |
1902 | struct list_head *head_page_with_bit; | |
625ed527 | 1903 | struct buffer_page *hpage = rb_set_head_page(cpu_buffer); |
77ae365e | 1904 | |
625ed527 | 1905 | if (!hpage) |
54f7be5b | 1906 | break; |
625ed527 | 1907 | head_page = &hpage->list; |
5040b4b7 VN |
1908 | prev_page = head_page->prev; |
1909 | ||
1910 | first_page = pages->next; | |
1911 | last_page = pages->prev; | |
1912 | ||
1913 | head_page_with_bit = (struct list_head *) | |
1914 | ((unsigned long)head_page | RB_PAGE_HEAD); | |
1915 | ||
1916 | last_page->next = head_page_with_bit; | |
1917 | first_page->prev = prev_page; | |
1918 | ||
bdf4fb62 UB |
1919 | /* caution: head_page_with_bit gets updated on cmpxchg failure */ |
1920 | if (try_cmpxchg(&prev_page->next, | |
1921 | &head_page_with_bit, first_page)) { | |
5040b4b7 VN |
1922 | /* |
1923 | * yay, we replaced the page pointer to our new list, | |
1924 | * now, we just have to update to head page's prev | |
1925 | * pointer to point to end of list | |
1926 | */ | |
1927 | head_page->prev = last_page; | |
bc92b956 | 1928 | success = true; |
5040b4b7 VN |
1929 | break; |
1930 | } | |
7a8e76a3 | 1931 | } |
7a8e76a3 | 1932 | |
5040b4b7 VN |
1933 | if (success) |
1934 | INIT_LIST_HEAD(pages); | |
1935 | /* | |
1936 | * If we weren't successful in adding in new pages, warn and stop | |
1937 | * tracing | |
1938 | */ | |
1939 | RB_WARN_ON(cpu_buffer, !success); | |
88ca6a71 | 1940 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
5040b4b7 VN |
1941 | |
1942 | /* free pages if they weren't inserted */ | |
1943 | if (!success) { | |
1944 | struct buffer_page *bpage, *tmp; | |
1945 | list_for_each_entry_safe(bpage, tmp, &cpu_buffer->new_pages, | |
1946 | list) { | |
1947 | list_del_init(&bpage->list); | |
1948 | free_buffer_page(bpage); | |
1949 | } | |
1950 | } | |
1951 | return success; | |
7a8e76a3 SR |
1952 | } |
1953 | ||
83f40318 | 1954 | static void rb_update_pages(struct ring_buffer_per_cpu *cpu_buffer) |
438ced17 | 1955 | { |
bc92b956 | 1956 | bool success; |
5040b4b7 | 1957 | |
438ced17 | 1958 | if (cpu_buffer->nr_pages_to_update > 0) |
5040b4b7 | 1959 | success = rb_insert_pages(cpu_buffer); |
438ced17 | 1960 | else |
5040b4b7 VN |
1961 | success = rb_remove_pages(cpu_buffer, |
1962 | -cpu_buffer->nr_pages_to_update); | |
83f40318 | 1963 | |
5040b4b7 VN |
1964 | if (success) |
1965 | cpu_buffer->nr_pages += cpu_buffer->nr_pages_to_update; | |
83f40318 VN |
1966 | } |
1967 | ||
1968 | static void update_pages_handler(struct work_struct *work) | |
1969 | { | |
1970 | struct ring_buffer_per_cpu *cpu_buffer = container_of(work, | |
1971 | struct ring_buffer_per_cpu, update_pages_work); | |
1972 | rb_update_pages(cpu_buffer); | |
05fdd70d | 1973 | complete(&cpu_buffer->update_done); |
438ced17 VN |
1974 | } |
1975 | ||
7a8e76a3 SR |
1976 | /** |
1977 | * ring_buffer_resize - resize the ring buffer | |
1978 | * @buffer: the buffer to resize. | |
1979 | * @size: the new size. | |
d611851b | 1980 | * @cpu_id: the cpu buffer to resize |
7a8e76a3 | 1981 | * |
139f8400 | 1982 | * Minimum size is 2 * buffer->subbuf_size. |
7a8e76a3 | 1983 | * |
83f40318 | 1984 | * Returns 0 on success and < 0 on failure. |
7a8e76a3 | 1985 | */ |
13292494 | 1986 | int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, |
438ced17 | 1987 | int cpu_id) |
7a8e76a3 SR |
1988 | { |
1989 | struct ring_buffer_per_cpu *cpu_buffer; | |
9b94a8fb | 1990 | unsigned long nr_pages; |
0a1754b2 | 1991 | int cpu, err; |
7a8e76a3 | 1992 | |
ee51a1de IM |
1993 | /* |
1994 | * Always succeed at resizing a non-existent buffer: | |
1995 | */ | |
1996 | if (!buffer) | |
0a1754b2 | 1997 | return 0; |
ee51a1de | 1998 | |
6a31e1f1 SR |
1999 | /* Make sure the requested buffer exists */ |
2000 | if (cpu_id != RING_BUFFER_ALL_CPUS && | |
2001 | !cpumask_test_cpu(cpu_id, buffer->cpumask)) | |
0a1754b2 | 2002 | return 0; |
6a31e1f1 | 2003 | |
139f8400 | 2004 | nr_pages = DIV_ROUND_UP(size, buffer->subbuf_size); |
7a8e76a3 SR |
2005 | |
2006 | /* we need a minimum of two pages */ | |
59643d15 SRRH |
2007 | if (nr_pages < 2) |
2008 | nr_pages = 2; | |
7a8e76a3 | 2009 | |
83f40318 | 2010 | /* prevent another thread from changing buffer sizes */ |
7a8e76a3 | 2011 | mutex_lock(&buffer->mutex); |
8a96c028 | 2012 | atomic_inc(&buffer->resizing); |
07b8b10e | 2013 | |
438ced17 | 2014 | if (cpu_id == RING_BUFFER_ALL_CPUS) { |
07b8b10e SRV |
2015 | /* |
2016 | * Don't succeed if resizing is disabled, as a reader might be | |
2017 | * manipulating the ring buffer and is expecting a sane state while | |
2018 | * this is true. | |
2019 | */ | |
2020 | for_each_buffer_cpu(buffer, cpu) { | |
2021 | cpu_buffer = buffer->buffers[cpu]; | |
2022 | if (atomic_read(&cpu_buffer->resize_disabled)) { | |
2023 | err = -EBUSY; | |
2024 | goto out_err_unlock; | |
2025 | } | |
2026 | } | |
2027 | ||
438ced17 | 2028 | /* calculate the pages to update */ |
7a8e76a3 SR |
2029 | for_each_buffer_cpu(buffer, cpu) { |
2030 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 | 2031 | |
438ced17 VN |
2032 | cpu_buffer->nr_pages_to_update = nr_pages - |
2033 | cpu_buffer->nr_pages; | |
438ced17 VN |
2034 | /* |
2035 | * nothing more to do for removing pages or no update | |
2036 | */ | |
2037 | if (cpu_buffer->nr_pages_to_update <= 0) | |
2038 | continue; | |
d7ec4bfe | 2039 | /* |
438ced17 VN |
2040 | * to add pages, make sure all new pages can be |
2041 | * allocated without receiving ENOMEM | |
d7ec4bfe | 2042 | */ |
438ced17 | 2043 | INIT_LIST_HEAD(&cpu_buffer->new_pages); |
74e2afc6 QH |
2044 | if (__rb_allocate_pages(cpu_buffer, cpu_buffer->nr_pages_to_update, |
2045 | &cpu_buffer->new_pages)) { | |
438ced17 | 2046 | /* not enough memory for new pages */ |
83f40318 VN |
2047 | err = -ENOMEM; |
2048 | goto out_err; | |
2049 | } | |
f6bd2c92 ZY |
2050 | |
2051 | cond_resched(); | |
83f40318 VN |
2052 | } |
2053 | ||
99c37d1a | 2054 | cpus_read_lock(); |
83f40318 VN |
2055 | /* |
2056 | * Fire off all the required work handlers | |
05fdd70d | 2057 | * We can't schedule on offline CPUs, but it's not necessary |
83f40318 VN |
2058 | * since we can change their buffer sizes without any race. |
2059 | */ | |
2060 | for_each_buffer_cpu(buffer, cpu) { | |
2061 | cpu_buffer = buffer->buffers[cpu]; | |
05fdd70d | 2062 | if (!cpu_buffer->nr_pages_to_update) |
83f40318 VN |
2063 | continue; |
2064 | ||
021c5b34 CM |
2065 | /* Can't run something on an offline CPU. */ |
2066 | if (!cpu_online(cpu)) { | |
f5eb5588 SRRH |
2067 | rb_update_pages(cpu_buffer); |
2068 | cpu_buffer->nr_pages_to_update = 0; | |
2069 | } else { | |
88ca6a71 SR |
2070 | /* Run directly if possible. */ |
2071 | migrate_disable(); | |
2072 | if (cpu != smp_processor_id()) { | |
2073 | migrate_enable(); | |
2074 | schedule_work_on(cpu, | |
2075 | &cpu_buffer->update_pages_work); | |
2076 | } else { | |
2077 | update_pages_handler(&cpu_buffer->update_pages_work); | |
2078 | migrate_enable(); | |
2079 | } | |
f5eb5588 | 2080 | } |
7a8e76a3 | 2081 | } |
7a8e76a3 | 2082 | |
438ced17 VN |
2083 | /* wait for all the updates to complete */ |
2084 | for_each_buffer_cpu(buffer, cpu) { | |
2085 | cpu_buffer = buffer->buffers[cpu]; | |
05fdd70d | 2086 | if (!cpu_buffer->nr_pages_to_update) |
83f40318 VN |
2087 | continue; |
2088 | ||
05fdd70d VN |
2089 | if (cpu_online(cpu)) |
2090 | wait_for_completion(&cpu_buffer->update_done); | |
83f40318 | 2091 | cpu_buffer->nr_pages_to_update = 0; |
438ced17 | 2092 | } |
83f40318 | 2093 | |
99c37d1a | 2094 | cpus_read_unlock(); |
438ced17 VN |
2095 | } else { |
2096 | cpu_buffer = buffer->buffers[cpu_id]; | |
83f40318 | 2097 | |
438ced17 VN |
2098 | if (nr_pages == cpu_buffer->nr_pages) |
2099 | goto out; | |
7a8e76a3 | 2100 | |
07b8b10e SRV |
2101 | /* |
2102 | * Don't succeed if resizing is disabled, as a reader might be | |
2103 | * manipulating the ring buffer and is expecting a sane state while | |
2104 | * this is true. | |
2105 | */ | |
2106 | if (atomic_read(&cpu_buffer->resize_disabled)) { | |
2107 | err = -EBUSY; | |
2108 | goto out_err_unlock; | |
2109 | } | |
2110 | ||
438ced17 VN |
2111 | cpu_buffer->nr_pages_to_update = nr_pages - |
2112 | cpu_buffer->nr_pages; | |
2113 | ||
2114 | INIT_LIST_HEAD(&cpu_buffer->new_pages); | |
2115 | if (cpu_buffer->nr_pages_to_update > 0 && | |
74e2afc6 QH |
2116 | __rb_allocate_pages(cpu_buffer, cpu_buffer->nr_pages_to_update, |
2117 | &cpu_buffer->new_pages)) { | |
83f40318 VN |
2118 | err = -ENOMEM; |
2119 | goto out_err; | |
2120 | } | |
438ced17 | 2121 | |
99c37d1a | 2122 | cpus_read_lock(); |
83f40318 | 2123 | |
021c5b34 CM |
2124 | /* Can't run something on an offline CPU. */ |
2125 | if (!cpu_online(cpu_id)) | |
f5eb5588 SRRH |
2126 | rb_update_pages(cpu_buffer); |
2127 | else { | |
88ca6a71 SR |
2128 | /* Run directly if possible. */ |
2129 | migrate_disable(); | |
2130 | if (cpu_id == smp_processor_id()) { | |
2131 | rb_update_pages(cpu_buffer); | |
2132 | migrate_enable(); | |
2133 | } else { | |
2134 | migrate_enable(); | |
2135 | schedule_work_on(cpu_id, | |
2136 | &cpu_buffer->update_pages_work); | |
2137 | wait_for_completion(&cpu_buffer->update_done); | |
2138 | } | |
f5eb5588 | 2139 | } |
83f40318 | 2140 | |
83f40318 | 2141 | cpu_buffer->nr_pages_to_update = 0; |
99c37d1a | 2142 | cpus_read_unlock(); |
438ced17 | 2143 | } |
7a8e76a3 SR |
2144 | |
2145 | out: | |
659f451f SR |
2146 | /* |
2147 | * The ring buffer resize can happen with the ring buffer | |
2148 | * enabled, so that the update disturbs the tracing as little | |
2149 | * as possible. But if the buffer is disabled, we do not need | |
2150 | * to worry about that, and we can take the time to verify | |
2151 | * that the buffer is not corrupt. | |
2152 | */ | |
2153 | if (atomic_read(&buffer->record_disabled)) { | |
2154 | atomic_inc(&buffer->record_disabled); | |
2155 | /* | |
2156 | * Even though the buffer was disabled, we must make sure | |
2157 | * that it is truly disabled before calling rb_check_pages. | |
2158 | * There could have been a race between checking | |
2159 | * record_disable and incrementing it. | |
2160 | */ | |
74401729 | 2161 | synchronize_rcu(); |
659f451f SR |
2162 | for_each_buffer_cpu(buffer, cpu) { |
2163 | cpu_buffer = buffer->buffers[cpu]; | |
2164 | rb_check_pages(cpu_buffer); | |
2165 | } | |
2166 | atomic_dec(&buffer->record_disabled); | |
2167 | } | |
2168 | ||
8a96c028 | 2169 | atomic_dec(&buffer->resizing); |
7a8e76a3 | 2170 | mutex_unlock(&buffer->mutex); |
0a1754b2 | 2171 | return 0; |
7a8e76a3 | 2172 | |
83f40318 | 2173 | out_err: |
438ced17 VN |
2174 | for_each_buffer_cpu(buffer, cpu) { |
2175 | struct buffer_page *bpage, *tmp; | |
83f40318 | 2176 | |
438ced17 | 2177 | cpu_buffer = buffer->buffers[cpu]; |
438ced17 | 2178 | cpu_buffer->nr_pages_to_update = 0; |
83f40318 | 2179 | |
438ced17 VN |
2180 | if (list_empty(&cpu_buffer->new_pages)) |
2181 | continue; | |
83f40318 | 2182 | |
438ced17 VN |
2183 | list_for_each_entry_safe(bpage, tmp, &cpu_buffer->new_pages, |
2184 | list) { | |
2185 | list_del_init(&bpage->list); | |
2186 | free_buffer_page(bpage); | |
2187 | } | |
7a8e76a3 | 2188 | } |
07b8b10e | 2189 | out_err_unlock: |
8a96c028 | 2190 | atomic_dec(&buffer->resizing); |
641d2f63 | 2191 | mutex_unlock(&buffer->mutex); |
83f40318 | 2192 | return err; |
7a8e76a3 | 2193 | } |
c4f50183 | 2194 | EXPORT_SYMBOL_GPL(ring_buffer_resize); |
7a8e76a3 | 2195 | |
13292494 | 2196 | void ring_buffer_change_overwrite(struct trace_buffer *buffer, int val) |
750912fa DS |
2197 | { |
2198 | mutex_lock(&buffer->mutex); | |
2199 | if (val) | |
2200 | buffer->flags |= RB_FL_OVERWRITE; | |
2201 | else | |
2202 | buffer->flags &= ~RB_FL_OVERWRITE; | |
2203 | mutex_unlock(&buffer->mutex); | |
2204 | } | |
2205 | EXPORT_SYMBOL_GPL(ring_buffer_change_overwrite); | |
2206 | ||
2289d567 | 2207 | static __always_inline void *__rb_page_index(struct buffer_page *bpage, unsigned index) |
7a8e76a3 | 2208 | { |
044fa782 | 2209 | return bpage->page->data + index; |
7a8e76a3 SR |
2210 | } |
2211 | ||
2289d567 | 2212 | static __always_inline struct ring_buffer_event * |
d769041f | 2213 | rb_reader_event(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 2214 | { |
6f807acd SR |
2215 | return __rb_page_index(cpu_buffer->reader_page, |
2216 | cpu_buffer->reader_page->read); | |
2217 | } | |
2218 | ||
785888c5 SRV |
2219 | static struct ring_buffer_event * |
2220 | rb_iter_head_event(struct ring_buffer_iter *iter) | |
bf41a158 | 2221 | { |
785888c5 SRV |
2222 | struct ring_buffer_event *event; |
2223 | struct buffer_page *iter_head_page = iter->head_page; | |
2224 | unsigned long commit; | |
2225 | unsigned length; | |
2226 | ||
153368ce SRV |
2227 | if (iter->head != iter->next_event) |
2228 | return iter->event; | |
2229 | ||
785888c5 SRV |
2230 | /* |
2231 | * When the writer goes across pages, it issues a cmpxchg which | |
2232 | * is a mb(), which will synchronize with the rmb here. | |
2233 | * (see rb_tail_page_update() and __rb_reserve_next()) | |
2234 | */ | |
2235 | commit = rb_page_commit(iter_head_page); | |
2236 | smp_rmb(); | |
95a404bd SRG |
2237 | |
2238 | /* An event needs to be at least 8 bytes in size */ | |
2239 | if (iter->head > commit - 8) | |
2240 | goto reset; | |
2241 | ||
785888c5 SRV |
2242 | event = __rb_page_index(iter_head_page, iter->head); |
2243 | length = rb_event_length(event); | |
2244 | ||
2245 | /* | |
2246 | * READ_ONCE() doesn't work on functions and we don't want the | |
2247 | * compiler doing any crazy optimizations with length. | |
2248 | */ | |
2249 | barrier(); | |
2250 | ||
139f8400 | 2251 | if ((iter->head + length) > commit || length > iter->event_size) |
785888c5 SRV |
2252 | /* Writer corrupted the read? */ |
2253 | goto reset; | |
2254 | ||
2255 | memcpy(iter->event, event, length); | |
2256 | /* | |
2257 | * If the page stamp is still the same after this rmb() then the | |
2258 | * event was safely copied without the writer entering the page. | |
2259 | */ | |
2260 | smp_rmb(); | |
2261 | ||
2262 | /* Make sure the page didn't change since we read this */ | |
2263 | if (iter->page_stamp != iter_head_page->page->time_stamp || | |
2264 | commit > rb_page_commit(iter_head_page)) | |
2265 | goto reset; | |
2266 | ||
2267 | iter->next_event = iter->head + length; | |
2268 | return iter->event; | |
2269 | reset: | |
2270 | /* Reset to the beginning */ | |
2271 | iter->page_stamp = iter->read_stamp = iter->head_page->page->time_stamp; | |
2272 | iter->head = 0; | |
2273 | iter->next_event = 0; | |
c9b7a4a7 | 2274 | iter->missed_events = 1; |
785888c5 | 2275 | return NULL; |
bf41a158 SR |
2276 | } |
2277 | ||
25985edc | 2278 | /* Size is determined by what has been committed */ |
2289d567 | 2279 | static __always_inline unsigned rb_page_size(struct buffer_page *bpage) |
bf41a158 SR |
2280 | { |
2281 | return rb_page_commit(bpage); | |
2282 | } | |
2283 | ||
2289d567 | 2284 | static __always_inline unsigned |
bf41a158 SR |
2285 | rb_commit_index(struct ring_buffer_per_cpu *cpu_buffer) |
2286 | { | |
2287 | return rb_page_commit(cpu_buffer->commit_page); | |
2288 | } | |
2289 | ||
2289d567 | 2290 | static __always_inline unsigned |
3cb30911 | 2291 | rb_event_index(struct ring_buffer_per_cpu *cpu_buffer, struct ring_buffer_event *event) |
bf41a158 SR |
2292 | { |
2293 | unsigned long addr = (unsigned long)event; | |
2294 | ||
3cb30911 SRG |
2295 | addr &= (PAGE_SIZE << cpu_buffer->buffer->subbuf_order) - 1; |
2296 | ||
2297 | return addr - BUF_PAGE_HDR_SIZE; | |
bf41a158 SR |
2298 | } |
2299 | ||
34a148bf | 2300 | static void rb_inc_iter(struct ring_buffer_iter *iter) |
d769041f SR |
2301 | { |
2302 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
2303 | ||
2304 | /* | |
2305 | * The iterator could be on the reader page (it starts there). | |
2306 | * But the head could have moved, since the reader was | |
2307 | * found. Check for this case and assign the iterator | |
2308 | * to the head page instead of next. | |
2309 | */ | |
2310 | if (iter->head_page == cpu_buffer->reader_page) | |
77ae365e | 2311 | iter->head_page = rb_set_head_page(cpu_buffer); |
d769041f | 2312 | else |
6689bed3 | 2313 | rb_inc_page(&iter->head_page); |
d769041f | 2314 | |
28e3fc56 | 2315 | iter->page_stamp = iter->read_stamp = iter->head_page->page->time_stamp; |
7a8e76a3 | 2316 | iter->head = 0; |
785888c5 | 2317 | iter->next_event = 0; |
7a8e76a3 SR |
2318 | } |
2319 | ||
77ae365e SR |
2320 | /* |
2321 | * rb_handle_head_page - writer hit the head page | |
2322 | * | |
2323 | * Returns: +1 to retry page | |
2324 | * 0 to continue | |
2325 | * -1 on error | |
2326 | */ | |
2327 | static int | |
2328 | rb_handle_head_page(struct ring_buffer_per_cpu *cpu_buffer, | |
2329 | struct buffer_page *tail_page, | |
2330 | struct buffer_page *next_page) | |
2331 | { | |
2332 | struct buffer_page *new_head; | |
2333 | int entries; | |
2334 | int type; | |
2335 | int ret; | |
2336 | ||
2337 | entries = rb_page_entries(next_page); | |
2338 | ||
2339 | /* | |
2340 | * The hard part is here. We need to move the head | |
2341 | * forward, and protect against both readers on | |
2342 | * other CPUs and writers coming in via interrupts. | |
2343 | */ | |
2344 | type = rb_head_page_set_update(cpu_buffer, next_page, tail_page, | |
2345 | RB_PAGE_HEAD); | |
2346 | ||
2347 | /* | |
2348 | * type can be one of four: | |
2349 | * NORMAL - an interrupt already moved it for us | |
2350 | * HEAD - we are the first to get here. | |
2351 | * UPDATE - we are the interrupt interrupting | |
2352 | * a current move. | |
2353 | * MOVED - a reader on another CPU moved the next | |
2354 | * pointer to its reader page. Give up | |
2355 | * and try again. | |
2356 | */ | |
2357 | ||
2358 | switch (type) { | |
2359 | case RB_PAGE_HEAD: | |
2360 | /* | |
2361 | * We changed the head to UPDATE, thus | |
2362 | * it is our responsibility to update | |
2363 | * the counters. | |
2364 | */ | |
2365 | local_add(entries, &cpu_buffer->overrun); | |
45d99ea4 | 2366 | local_sub(rb_page_commit(next_page), &cpu_buffer->entries_bytes); |
31029a8b | 2367 | local_inc(&cpu_buffer->pages_lost); |
77ae365e SR |
2368 | |
2369 | /* | |
2370 | * The entries will be zeroed out when we move the | |
2371 | * tail page. | |
2372 | */ | |
2373 | ||
2374 | /* still more to do */ | |
2375 | break; | |
2376 | ||
2377 | case RB_PAGE_UPDATE: | |
2378 | /* | |
2379 | * This is an interrupt that interrupt the | |
2380 | * previous update. Still more to do. | |
2381 | */ | |
2382 | break; | |
2383 | case RB_PAGE_NORMAL: | |
2384 | /* | |
2385 | * An interrupt came in before the update | |
2386 | * and processed this for us. | |
2387 | * Nothing left to do. | |
2388 | */ | |
2389 | return 1; | |
2390 | case RB_PAGE_MOVED: | |
2391 | /* | |
2392 | * The reader is on another CPU and just did | |
2393 | * a swap with our next_page. | |
2394 | * Try again. | |
2395 | */ | |
2396 | return 1; | |
2397 | default: | |
2398 | RB_WARN_ON(cpu_buffer, 1); /* WTF??? */ | |
2399 | return -1; | |
2400 | } | |
2401 | ||
2402 | /* | |
2403 | * Now that we are here, the old head pointer is | |
2404 | * set to UPDATE. This will keep the reader from | |
2405 | * swapping the head page with the reader page. | |
2406 | * The reader (on another CPU) will spin till | |
2407 | * we are finished. | |
2408 | * | |
2409 | * We just need to protect against interrupts | |
2410 | * doing the job. We will set the next pointer | |
2411 | * to HEAD. After that, we set the old pointer | |
2412 | * to NORMAL, but only if it was HEAD before. | |
2413 | * otherwise we are an interrupt, and only | |
2414 | * want the outer most commit to reset it. | |
2415 | */ | |
2416 | new_head = next_page; | |
6689bed3 | 2417 | rb_inc_page(&new_head); |
77ae365e SR |
2418 | |
2419 | ret = rb_head_page_set_head(cpu_buffer, new_head, next_page, | |
2420 | RB_PAGE_NORMAL); | |
2421 | ||
2422 | /* | |
2423 | * Valid returns are: | |
2424 | * HEAD - an interrupt came in and already set it. | |
2425 | * NORMAL - One of two things: | |
2426 | * 1) We really set it. | |
2427 | * 2) A bunch of interrupts came in and moved | |
2428 | * the page forward again. | |
2429 | */ | |
2430 | switch (ret) { | |
2431 | case RB_PAGE_HEAD: | |
2432 | case RB_PAGE_NORMAL: | |
2433 | /* OK */ | |
2434 | break; | |
2435 | default: | |
2436 | RB_WARN_ON(cpu_buffer, 1); | |
2437 | return -1; | |
2438 | } | |
2439 | ||
2440 | /* | |
2441 | * It is possible that an interrupt came in, | |
2442 | * set the head up, then more interrupts came in | |
2443 | * and moved it again. When we get back here, | |
2444 | * the page would have been set to NORMAL but we | |
2445 | * just set it back to HEAD. | |
2446 | * | |
2447 | * How do you detect this? Well, if that happened | |
2448 | * the tail page would have moved. | |
2449 | */ | |
2450 | if (ret == RB_PAGE_NORMAL) { | |
8573636e SRRH |
2451 | struct buffer_page *buffer_tail_page; |
2452 | ||
2453 | buffer_tail_page = READ_ONCE(cpu_buffer->tail_page); | |
77ae365e SR |
2454 | /* |
2455 | * If the tail had moved passed next, then we need | |
2456 | * to reset the pointer. | |
2457 | */ | |
8573636e SRRH |
2458 | if (buffer_tail_page != tail_page && |
2459 | buffer_tail_page != next_page) | |
77ae365e SR |
2460 | rb_head_page_set_normal(cpu_buffer, new_head, |
2461 | next_page, | |
2462 | RB_PAGE_HEAD); | |
2463 | } | |
2464 | ||
2465 | /* | |
2466 | * If this was the outer most commit (the one that | |
2467 | * changed the original pointer from HEAD to UPDATE), | |
2468 | * then it is up to us to reset it to NORMAL. | |
2469 | */ | |
2470 | if (type == RB_PAGE_HEAD) { | |
2471 | ret = rb_head_page_set_normal(cpu_buffer, next_page, | |
2472 | tail_page, | |
2473 | RB_PAGE_UPDATE); | |
2474 | if (RB_WARN_ON(cpu_buffer, | |
2475 | ret != RB_PAGE_UPDATE)) | |
2476 | return -1; | |
2477 | } | |
2478 | ||
2479 | return 0; | |
2480 | } | |
2481 | ||
c7b09308 SR |
2482 | static inline void |
2483 | rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer, | |
fcc742ea | 2484 | unsigned long tail, struct rb_event_info *info) |
c7b09308 | 2485 | { |
139f8400 | 2486 | unsigned long bsize = READ_ONCE(cpu_buffer->buffer->subbuf_size); |
fcc742ea | 2487 | struct buffer_page *tail_page = info->tail_page; |
c7b09308 | 2488 | struct ring_buffer_event *event; |
fcc742ea | 2489 | unsigned long length = info->length; |
c7b09308 SR |
2490 | |
2491 | /* | |
2492 | * Only the event that crossed the page boundary | |
2493 | * must fill the old tail_page with padding. | |
2494 | */ | |
139f8400 | 2495 | if (tail >= bsize) { |
b3230c8b SR |
2496 | /* |
2497 | * If the page was filled, then we still need | |
2498 | * to update the real_end. Reset it to zero | |
2499 | * and the reader will ignore it. | |
2500 | */ | |
139f8400 | 2501 | if (tail == bsize) |
b3230c8b SR |
2502 | tail_page->real_end = 0; |
2503 | ||
c7b09308 SR |
2504 | local_sub(length, &tail_page->write); |
2505 | return; | |
2506 | } | |
2507 | ||
2508 | event = __rb_page_index(tail_page, tail); | |
2509 | ||
ff0ff84a SR |
2510 | /* |
2511 | * Save the original length to the meta data. | |
2512 | * This will be used by the reader to add lost event | |
2513 | * counter. | |
2514 | */ | |
2515 | tail_page->real_end = tail; | |
2516 | ||
c7b09308 SR |
2517 | /* |
2518 | * If this event is bigger than the minimum size, then | |
2519 | * we need to be careful that we don't subtract the | |
2520 | * write counter enough to allow another writer to slip | |
2521 | * in on this page. | |
2522 | * We put in a discarded commit instead, to make sure | |
45d99ea4 ZY |
2523 | * that this space is not used again, and this space will |
2524 | * not be accounted into 'entries_bytes'. | |
c7b09308 SR |
2525 | * |
2526 | * If we are less than the minimum size, we don't need to | |
2527 | * worry about it. | |
2528 | */ | |
139f8400 | 2529 | if (tail > (bsize - RB_EVNT_MIN_SIZE)) { |
c7b09308 SR |
2530 | /* No room for any events */ |
2531 | ||
2532 | /* Mark the rest of the page with padding */ | |
2533 | rb_event_set_padding(event); | |
2534 | ||
a0fcaaed SRG |
2535 | /* Make sure the padding is visible before the write update */ |
2536 | smp_wmb(); | |
2537 | ||
c7b09308 SR |
2538 | /* Set the write back to the previous setting */ |
2539 | local_sub(length, &tail_page->write); | |
2540 | return; | |
2541 | } | |
2542 | ||
2543 | /* Put in a discarded event */ | |
139f8400 | 2544 | event->array[0] = (bsize - tail) - RB_EVNT_HDR_SIZE; |
c7b09308 SR |
2545 | event->type_len = RINGBUF_TYPE_PADDING; |
2546 | /* time delta must be non zero */ | |
2547 | event->time_delta = 1; | |
c7b09308 | 2548 | |
45d99ea4 | 2549 | /* account for padding bytes */ |
139f8400 | 2550 | local_add(bsize - tail, &cpu_buffer->entries_bytes); |
45d99ea4 | 2551 | |
a0fcaaed SRG |
2552 | /* Make sure the padding is visible before the tail_page->write update */ |
2553 | smp_wmb(); | |
2554 | ||
c7b09308 | 2555 | /* Set write to end of buffer */ |
139f8400 | 2556 | length = (tail + length) - bsize; |
c7b09308 SR |
2557 | local_sub(length, &tail_page->write); |
2558 | } | |
6634ff26 | 2559 | |
4239c38f SRRH |
2560 | static inline void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer); |
2561 | ||
747e94ae SR |
2562 | /* |
2563 | * This is the slow path, force gcc not to inline it. | |
2564 | */ | |
2565 | static noinline struct ring_buffer_event * | |
6634ff26 | 2566 | rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer, |
fcc742ea | 2567 | unsigned long tail, struct rb_event_info *info) |
7a8e76a3 | 2568 | { |
fcc742ea | 2569 | struct buffer_page *tail_page = info->tail_page; |
5a50e33c | 2570 | struct buffer_page *commit_page = cpu_buffer->commit_page; |
13292494 | 2571 | struct trace_buffer *buffer = cpu_buffer->buffer; |
77ae365e SR |
2572 | struct buffer_page *next_page; |
2573 | int ret; | |
aa20ae84 SR |
2574 | |
2575 | next_page = tail_page; | |
2576 | ||
6689bed3 | 2577 | rb_inc_page(&next_page); |
aa20ae84 | 2578 | |
aa20ae84 SR |
2579 | /* |
2580 | * If for some reason, we had an interrupt storm that made | |
2581 | * it all the way around the buffer, bail, and warn | |
2582 | * about it. | |
2583 | */ | |
2584 | if (unlikely(next_page == commit_page)) { | |
77ae365e | 2585 | local_inc(&cpu_buffer->commit_overrun); |
aa20ae84 SR |
2586 | goto out_reset; |
2587 | } | |
2588 | ||
77ae365e SR |
2589 | /* |
2590 | * This is where the fun begins! | |
2591 | * | |
2592 | * We are fighting against races between a reader that | |
2593 | * could be on another CPU trying to swap its reader | |
2594 | * page with the buffer head. | |
2595 | * | |
2596 | * We are also fighting against interrupts coming in and | |
2597 | * moving the head or tail on us as well. | |
2598 | * | |
2599 | * If the next page is the head page then we have filled | |
2600 | * the buffer, unless the commit page is still on the | |
2601 | * reader page. | |
2602 | */ | |
6689bed3 | 2603 | if (rb_is_head_page(next_page, &tail_page->list)) { |
aa20ae84 | 2604 | |
77ae365e SR |
2605 | /* |
2606 | * If the commit is not on the reader page, then | |
2607 | * move the header page. | |
2608 | */ | |
2609 | if (!rb_is_reader_page(cpu_buffer->commit_page)) { | |
2610 | /* | |
2611 | * If we are not in overwrite mode, | |
2612 | * this is easy, just stop here. | |
2613 | */ | |
884bfe89 SP |
2614 | if (!(buffer->flags & RB_FL_OVERWRITE)) { |
2615 | local_inc(&cpu_buffer->dropped_events); | |
77ae365e | 2616 | goto out_reset; |
884bfe89 | 2617 | } |
77ae365e SR |
2618 | |
2619 | ret = rb_handle_head_page(cpu_buffer, | |
2620 | tail_page, | |
2621 | next_page); | |
2622 | if (ret < 0) | |
2623 | goto out_reset; | |
2624 | if (ret) | |
2625 | goto out_again; | |
2626 | } else { | |
2627 | /* | |
2628 | * We need to be careful here too. The | |
2629 | * commit page could still be on the reader | |
2630 | * page. We could have a small buffer, and | |
2631 | * have filled up the buffer with events | |
2632 | * from interrupts and such, and wrapped. | |
2633 | * | |
c6358bac | 2634 | * Note, if the tail page is also on the |
77ae365e SR |
2635 | * reader_page, we let it move out. |
2636 | */ | |
2637 | if (unlikely((cpu_buffer->commit_page != | |
2638 | cpu_buffer->tail_page) && | |
2639 | (cpu_buffer->commit_page == | |
2640 | cpu_buffer->reader_page))) { | |
2641 | local_inc(&cpu_buffer->commit_overrun); | |
2642 | goto out_reset; | |
2643 | } | |
aa20ae84 SR |
2644 | } |
2645 | } | |
2646 | ||
70004986 | 2647 | rb_tail_page_update(cpu_buffer, tail_page, next_page); |
aa20ae84 | 2648 | |
77ae365e | 2649 | out_again: |
aa20ae84 | 2650 | |
fcc742ea | 2651 | rb_reset_tail(cpu_buffer, tail, info); |
aa20ae84 | 2652 | |
4239c38f SRRH |
2653 | /* Commit what we have for now. */ |
2654 | rb_end_commit(cpu_buffer); | |
2655 | /* rb_end_commit() decs committing */ | |
2656 | local_inc(&cpu_buffer->committing); | |
2657 | ||
aa20ae84 SR |
2658 | /* fail and let the caller try again */ |
2659 | return ERR_PTR(-EAGAIN); | |
2660 | ||
45141d46 | 2661 | out_reset: |
6f3b3440 | 2662 | /* reset write */ |
fcc742ea | 2663 | rb_reset_tail(cpu_buffer, tail, info); |
6f3b3440 | 2664 | |
bf41a158 | 2665 | return NULL; |
7a8e76a3 SR |
2666 | } |
2667 | ||
74e87937 SRV |
2668 | /* Slow path */ |
2669 | static struct ring_buffer_event * | |
3cb30911 SRG |
2670 | rb_add_time_stamp(struct ring_buffer_per_cpu *cpu_buffer, |
2671 | struct ring_buffer_event *event, u64 delta, bool abs) | |
9826b273 | 2672 | { |
dc4e2801 TZ |
2673 | if (abs) |
2674 | event->type_len = RINGBUF_TYPE_TIME_STAMP; | |
2675 | else | |
2676 | event->type_len = RINGBUF_TYPE_TIME_EXTEND; | |
9826b273 | 2677 | |
dc4e2801 | 2678 | /* Not the first event on the page, or not delta? */ |
3cb30911 | 2679 | if (abs || rb_event_index(cpu_buffer, event)) { |
d90fd774 SRRH |
2680 | event->time_delta = delta & TS_MASK; |
2681 | event->array[0] = delta >> TS_SHIFT; | |
2682 | } else { | |
2683 | /* nope, just zero it */ | |
2684 | event->time_delta = 0; | |
2685 | event->array[0] = 0; | |
2686 | } | |
a4543a2f | 2687 | |
d90fd774 SRRH |
2688 | return skip_time_extend(event); |
2689 | } | |
a4543a2f | 2690 | |
58fbc3c6 SRV |
2691 | #ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK |
2692 | static inline bool sched_clock_stable(void) | |
2693 | { | |
2694 | return true; | |
2695 | } | |
2696 | #endif | |
2697 | ||
74e87937 | 2698 | static void |
58fbc3c6 SRV |
2699 | rb_check_timestamp(struct ring_buffer_per_cpu *cpu_buffer, |
2700 | struct rb_event_info *info) | |
2701 | { | |
2702 | u64 write_stamp; | |
2703 | ||
29ce2451 | 2704 | WARN_ONCE(1, "Delta way too big! %llu ts=%llu before=%llu after=%llu write stamp=%llu\n%s", |
58fbc3c6 SRV |
2705 | (unsigned long long)info->delta, |
2706 | (unsigned long long)info->ts, | |
2707 | (unsigned long long)info->before, | |
2708 | (unsigned long long)info->after, | |
c84897c0 | 2709 | (unsigned long long)({rb_time_read(&cpu_buffer->write_stamp, &write_stamp); write_stamp;}), |
58fbc3c6 SRV |
2710 | sched_clock_stable() ? "" : |
2711 | "If you just came from a suspend/resume,\n" | |
2712 | "please switch to the trace global clock:\n" | |
2455f0e1 | 2713 | " echo global > /sys/kernel/tracing/trace_clock\n" |
58fbc3c6 SRV |
2714 | "or add trace_clock=global to the kernel command line\n"); |
2715 | } | |
2716 | ||
74e87937 SRV |
2717 | static void rb_add_timestamp(struct ring_buffer_per_cpu *cpu_buffer, |
2718 | struct ring_buffer_event **event, | |
2719 | struct rb_event_info *info, | |
2720 | u64 *delta, | |
2721 | unsigned int *length) | |
2722 | { | |
2723 | bool abs = info->add_timestamp & | |
2724 | (RB_ADD_STAMP_FORCE | RB_ADD_STAMP_ABSOLUTE); | |
2725 | ||
29ce2451 | 2726 | if (unlikely(info->delta > (1ULL << 59))) { |
6695da58 SRG |
2727 | /* |
2728 | * Some timers can use more than 59 bits, and when a timestamp | |
2729 | * is added to the buffer, it will lose those bits. | |
2730 | */ | |
2731 | if (abs && (info->ts & TS_MSB)) { | |
2732 | info->delta &= ABS_TS_MASK; | |
2733 | ||
29ce2451 | 2734 | /* did the clock go backwards */ |
6695da58 | 2735 | } else if (info->before == info->after && info->before > info->ts) { |
29ce2451 SRV |
2736 | /* not interrupted */ |
2737 | static int once; | |
2738 | ||
2739 | /* | |
2740 | * This is possible with a recalibrating of the TSC. | |
2741 | * Do not produce a call stack, but just report it. | |
2742 | */ | |
2743 | if (!once) { | |
2744 | once++; | |
2745 | pr_warn("Ring buffer clock went backwards: %llu -> %llu\n", | |
2746 | info->before, info->ts); | |
2747 | } | |
2748 | } else | |
2749 | rb_check_timestamp(cpu_buffer, info); | |
2750 | if (!abs) | |
2751 | info->delta = 0; | |
2752 | } | |
3cb30911 | 2753 | *event = rb_add_time_stamp(cpu_buffer, *event, info->delta, abs); |
74e87937 SRV |
2754 | *length -= RB_LEN_TIME_EXTEND; |
2755 | *delta = 0; | |
2756 | } | |
2757 | ||
d90fd774 SRRH |
2758 | /** |
2759 | * rb_update_event - update event type and data | |
cfc585a4 | 2760 | * @cpu_buffer: The per cpu buffer of the @event |
d90fd774 | 2761 | * @event: the event to update |
cfc585a4 | 2762 | * @info: The info to update the @event with (contains length and delta) |
d90fd774 | 2763 | * |
cfc585a4 | 2764 | * Update the type and data fields of the @event. The length |
d90fd774 SRRH |
2765 | * is the actual size that is written to the ring buffer, |
2766 | * and with this, we can determine what to place into the | |
2767 | * data field. | |
2768 | */ | |
b7dc42fd | 2769 | static void |
d90fd774 SRRH |
2770 | rb_update_event(struct ring_buffer_per_cpu *cpu_buffer, |
2771 | struct ring_buffer_event *event, | |
2772 | struct rb_event_info *info) | |
2773 | { | |
2774 | unsigned length = info->length; | |
2775 | u64 delta = info->delta; | |
8672e494 SRV |
2776 | unsigned int nest = local_read(&cpu_buffer->committing) - 1; |
2777 | ||
a948c69d | 2778 | if (!WARN_ON_ONCE(nest >= MAX_NEST)) |
8672e494 | 2779 | cpu_buffer->event_stamp[nest] = info->ts; |
a4543a2f SRRH |
2780 | |
2781 | /* | |
d90fd774 | 2782 | * If we need to add a timestamp, then we |
6167c205 | 2783 | * add it to the start of the reserved space. |
a4543a2f | 2784 | */ |
74e87937 SRV |
2785 | if (unlikely(info->add_timestamp)) |
2786 | rb_add_timestamp(cpu_buffer, &event, info, &delta, &length); | |
a4543a2f | 2787 | |
d90fd774 SRRH |
2788 | event->time_delta = delta; |
2789 | length -= RB_EVNT_HDR_SIZE; | |
adab66b7 | 2790 | if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) { |
d90fd774 SRRH |
2791 | event->type_len = 0; |
2792 | event->array[0] = length; | |
2793 | } else | |
2794 | event->type_len = DIV_ROUND_UP(length, RB_ALIGNMENT); | |
2795 | } | |
2796 | ||
2797 | static unsigned rb_calculate_event_length(unsigned length) | |
2798 | { | |
2799 | struct ring_buffer_event event; /* Used only for sizeof array */ | |
2800 | ||
2801 | /* zero length can cause confusions */ | |
2802 | if (!length) | |
2803 | length++; | |
2804 | ||
adab66b7 | 2805 | if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) |
d90fd774 SRRH |
2806 | length += sizeof(event.array[0]); |
2807 | ||
2808 | length += RB_EVNT_HDR_SIZE; | |
adab66b7 | 2809 | length = ALIGN(length, RB_ARCH_ALIGNMENT); |
d90fd774 SRRH |
2810 | |
2811 | /* | |
2812 | * In case the time delta is larger than the 27 bits for it | |
2813 | * in the header, we need to add a timestamp. If another | |
2814 | * event comes in when trying to discard this one to increase | |
2815 | * the length, then the timestamp will be added in the allocated | |
2816 | * space of this event. If length is bigger than the size needed | |
2817 | * for the TIME_EXTEND, then padding has to be used. The events | |
2818 | * length must be either RB_LEN_TIME_EXTEND, or greater than or equal | |
2819 | * to RB_LEN_TIME_EXTEND + 8, as 8 is the minimum size for padding. | |
2820 | * As length is a multiple of 4, we only need to worry if it | |
2821 | * is 12 (RB_LEN_TIME_EXTEND + 4). | |
2822 | */ | |
2823 | if (length == RB_LEN_TIME_EXTEND + RB_ALIGNMENT) | |
2824 | length += RB_ALIGNMENT; | |
2825 | ||
2826 | return length; | |
2827 | } | |
2828 | ||
bc92b956 | 2829 | static inline bool |
d90fd774 SRRH |
2830 | rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer, |
2831 | struct ring_buffer_event *event) | |
2832 | { | |
2833 | unsigned long new_index, old_index; | |
2834 | struct buffer_page *bpage; | |
d90fd774 SRRH |
2835 | unsigned long addr; |
2836 | ||
3cb30911 | 2837 | new_index = rb_event_index(cpu_buffer, event); |
d90fd774 SRRH |
2838 | old_index = new_index + rb_event_ts_length(event); |
2839 | addr = (unsigned long)event; | |
3cb30911 | 2840 | addr &= ~((PAGE_SIZE << cpu_buffer->buffer->subbuf_order) - 1); |
d90fd774 | 2841 | |
8573636e | 2842 | bpage = READ_ONCE(cpu_buffer->tail_page); |
d90fd774 | 2843 | |
083e9f65 SRG |
2844 | /* |
2845 | * Make sure the tail_page is still the same and | |
2846 | * the next write location is the end of this event | |
2847 | */ | |
d90fd774 SRRH |
2848 | if (bpage->page == (void *)addr && rb_page_write(bpage) == old_index) { |
2849 | unsigned long write_mask = | |
2850 | local_read(&bpage->write) & ~RB_WRITE_MASK; | |
2851 | unsigned long event_length = rb_event_length(event); | |
a389d86f | 2852 | |
b2dd7975 SRG |
2853 | /* |
2854 | * For the before_stamp to be different than the write_stamp | |
2855 | * to make sure that the next event adds an absolute | |
2856 | * value and does not rely on the saved write stamp, which | |
2857 | * is now going to be bogus. | |
083e9f65 SRG |
2858 | * |
2859 | * By setting the before_stamp to zero, the next event | |
2860 | * is not going to use the write_stamp and will instead | |
2861 | * create an absolute timestamp. This means there's no | |
2862 | * reason to update the wirte_stamp! | |
b2dd7975 SRG |
2863 | */ |
2864 | rb_time_set(&cpu_buffer->before_stamp, 0); | |
2865 | ||
a389d86f SRV |
2866 | /* |
2867 | * If an event were to come in now, it would see that the | |
2868 | * write_stamp and the before_stamp are different, and assume | |
2869 | * that this event just added itself before updating | |
2870 | * the write stamp. The interrupting event will fix the | |
083e9f65 | 2871 | * write stamp for us, and use an absolute timestamp. |
a389d86f SRV |
2872 | */ |
2873 | ||
d90fd774 SRRH |
2874 | /* |
2875 | * This is on the tail page. It is possible that | |
2876 | * a write could come in and move the tail page | |
2877 | * and write to the next page. That is fine | |
2878 | * because we just shorten what is on this page. | |
2879 | */ | |
2880 | old_index += write_mask; | |
2881 | new_index += write_mask; | |
00a8478f UB |
2882 | |
2883 | /* caution: old_index gets updated on cmpxchg failure */ | |
2884 | if (local_try_cmpxchg(&bpage->write, &old_index, new_index)) { | |
d90fd774 SRRH |
2885 | /* update counters */ |
2886 | local_sub(event_length, &cpu_buffer->entries_bytes); | |
bc92b956 | 2887 | return true; |
d90fd774 SRRH |
2888 | } |
2889 | } | |
2890 | ||
2891 | /* could not discard */ | |
bc92b956 | 2892 | return false; |
d90fd774 SRRH |
2893 | } |
2894 | ||
2895 | static void rb_start_commit(struct ring_buffer_per_cpu *cpu_buffer) | |
2896 | { | |
2897 | local_inc(&cpu_buffer->committing); | |
2898 | local_inc(&cpu_buffer->commits); | |
2899 | } | |
2900 | ||
38e11df1 | 2901 | static __always_inline void |
d90fd774 SRRH |
2902 | rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) |
2903 | { | |
2904 | unsigned long max_count; | |
2905 | ||
2906 | /* | |
2907 | * We only race with interrupts and NMIs on this CPU. | |
2908 | * If we own the commit event, then we can commit | |
2909 | * all others that interrupted us, since the interruptions | |
2910 | * are in stack format (they finish before they come | |
2911 | * back to us). This allows us to do a simple loop to | |
2912 | * assign the commit to the tail. | |
2913 | */ | |
2914 | again: | |
2915 | max_count = cpu_buffer->nr_pages * 100; | |
2916 | ||
8573636e | 2917 | while (cpu_buffer->commit_page != READ_ONCE(cpu_buffer->tail_page)) { |
d90fd774 SRRH |
2918 | if (RB_WARN_ON(cpu_buffer, !(--max_count))) |
2919 | return; | |
2920 | if (RB_WARN_ON(cpu_buffer, | |
2921 | rb_is_reader_page(cpu_buffer->tail_page))) | |
2922 | return; | |
6455b616 ZY |
2923 | /* |
2924 | * No need for a memory barrier here, as the update | |
2925 | * of the tail_page did it for this page. | |
2926 | */ | |
d90fd774 SRRH |
2927 | local_set(&cpu_buffer->commit_page->page->commit, |
2928 | rb_page_write(cpu_buffer->commit_page)); | |
6689bed3 | 2929 | rb_inc_page(&cpu_buffer->commit_page); |
d90fd774 SRRH |
2930 | /* add barrier to keep gcc from optimizing too much */ |
2931 | barrier(); | |
2932 | } | |
2933 | while (rb_commit_index(cpu_buffer) != | |
2934 | rb_page_write(cpu_buffer->commit_page)) { | |
2935 | ||
6455b616 ZY |
2936 | /* Make sure the readers see the content of what is committed. */ |
2937 | smp_wmb(); | |
d90fd774 SRRH |
2938 | local_set(&cpu_buffer->commit_page->page->commit, |
2939 | rb_page_write(cpu_buffer->commit_page)); | |
2940 | RB_WARN_ON(cpu_buffer, | |
2941 | local_read(&cpu_buffer->commit_page->page->commit) & | |
2942 | ~RB_WRITE_MASK); | |
2943 | barrier(); | |
2944 | } | |
2945 | ||
2946 | /* again, keep gcc from optimizing */ | |
2947 | barrier(); | |
2948 | ||
2949 | /* | |
2950 | * If an interrupt came in just after the first while loop | |
2951 | * and pushed the tail page forward, we will be left with | |
2952 | * a dangling commit that will never go forward. | |
2953 | */ | |
8573636e | 2954 | if (unlikely(cpu_buffer->commit_page != READ_ONCE(cpu_buffer->tail_page))) |
d90fd774 SRRH |
2955 | goto again; |
2956 | } | |
2957 | ||
38e11df1 | 2958 | static __always_inline void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer) |
d90fd774 SRRH |
2959 | { |
2960 | unsigned long commits; | |
2961 | ||
2962 | if (RB_WARN_ON(cpu_buffer, | |
2963 | !local_read(&cpu_buffer->committing))) | |
2964 | return; | |
2965 | ||
2966 | again: | |
2967 | commits = local_read(&cpu_buffer->commits); | |
2968 | /* synchronize with interrupts */ | |
2969 | barrier(); | |
2970 | if (local_read(&cpu_buffer->committing) == 1) | |
2971 | rb_set_commit_to_write(cpu_buffer); | |
2972 | ||
2973 | local_dec(&cpu_buffer->committing); | |
2974 | ||
2975 | /* synchronize with interrupts */ | |
2976 | barrier(); | |
2977 | ||
2978 | /* | |
2979 | * Need to account for interrupts coming in between the | |
2980 | * updating of the commit page and the clearing of the | |
2981 | * committing counter. | |
2982 | */ | |
2983 | if (unlikely(local_read(&cpu_buffer->commits) != commits) && | |
2984 | !local_read(&cpu_buffer->committing)) { | |
2985 | local_inc(&cpu_buffer->committing); | |
2986 | goto again; | |
2987 | } | |
2988 | } | |
2989 | ||
2990 | static inline void rb_event_discard(struct ring_buffer_event *event) | |
2991 | { | |
dc4e2801 | 2992 | if (extended_time(event)) |
d90fd774 SRRH |
2993 | event = skip_time_extend(event); |
2994 | ||
2995 | /* array[0] holds the actual length for the discarded event */ | |
2996 | event->array[0] = rb_event_data_length(event) - RB_EVNT_HDR_SIZE; | |
2997 | event->type_len = RINGBUF_TYPE_PADDING; | |
2998 | /* time delta must be non zero */ | |
2999 | if (!event->time_delta) | |
3000 | event->time_delta = 1; | |
3001 | } | |
3002 | ||
04aabc32 | 3003 | static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer) |
d90fd774 SRRH |
3004 | { |
3005 | local_inc(&cpu_buffer->entries); | |
d90fd774 SRRH |
3006 | rb_end_commit(cpu_buffer); |
3007 | } | |
3008 | ||
3009 | static __always_inline void | |
13292494 | 3010 | rb_wakeups(struct trace_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer) |
d90fd774 | 3011 | { |
d90fd774 SRRH |
3012 | if (buffer->irq_work.waiters_pending) { |
3013 | buffer->irq_work.waiters_pending = false; | |
3014 | /* irq_work_queue() supplies it's own memory barriers */ | |
3015 | irq_work_queue(&buffer->irq_work.work); | |
3016 | } | |
3017 | ||
3018 | if (cpu_buffer->irq_work.waiters_pending) { | |
3019 | cpu_buffer->irq_work.waiters_pending = false; | |
3020 | /* irq_work_queue() supplies it's own memory barriers */ | |
3021 | irq_work_queue(&cpu_buffer->irq_work.work); | |
3022 | } | |
3023 | ||
03329f99 SRV |
3024 | if (cpu_buffer->last_pages_touch == local_read(&cpu_buffer->pages_touched)) |
3025 | return; | |
d90fd774 | 3026 | |
03329f99 SRV |
3027 | if (cpu_buffer->reader_page == cpu_buffer->commit_page) |
3028 | return; | |
2c2b0a78 | 3029 | |
03329f99 SRV |
3030 | if (!cpu_buffer->irq_work.full_waiters_pending) |
3031 | return; | |
2c2b0a78 | 3032 | |
03329f99 SRV |
3033 | cpu_buffer->last_pages_touch = local_read(&cpu_buffer->pages_touched); |
3034 | ||
42fb0a1e | 3035 | if (!full_hit(buffer, cpu_buffer->cpu, cpu_buffer->shortest_full)) |
03329f99 SRV |
3036 | return; |
3037 | ||
3038 | cpu_buffer->irq_work.wakeup_full = true; | |
3039 | cpu_buffer->irq_work.full_waiters_pending = false; | |
3040 | /* irq_work_queue() supplies it's own memory barriers */ | |
3041 | irq_work_queue(&cpu_buffer->irq_work.work); | |
d90fd774 SRRH |
3042 | } |
3043 | ||
28575c61 SRV |
3044 | #ifdef CONFIG_RING_BUFFER_RECORD_RECURSION |
3045 | # define do_ring_buffer_record_recursion() \ | |
3046 | do_ftrace_record_recursion(_THIS_IP_, _RET_IP_) | |
3047 | #else | |
3048 | # define do_ring_buffer_record_recursion() do { } while (0) | |
3049 | #endif | |
3050 | ||
d90fd774 SRRH |
3051 | /* |
3052 | * The lock and unlock are done within a preempt disable section. | |
3053 | * The current_context per_cpu variable can only be modified | |
3054 | * by the current task between lock and unlock. But it can | |
a0e3a18f SRV |
3055 | * be modified more than once via an interrupt. To pass this |
3056 | * information from the lock to the unlock without having to | |
3057 | * access the 'in_interrupt()' functions again (which do show | |
3058 | * a bit of overhead in something as critical as function tracing, | |
3059 | * we use a bitmask trick. | |
d90fd774 | 3060 | * |
b02414c8 SRV |
3061 | * bit 1 = NMI context |
3062 | * bit 2 = IRQ context | |
3063 | * bit 3 = SoftIRQ context | |
3064 | * bit 4 = normal context. | |
d90fd774 | 3065 | * |
a0e3a18f SRV |
3066 | * This works because this is the order of contexts that can |
3067 | * preempt other contexts. A SoftIRQ never preempts an IRQ | |
3068 | * context. | |
3069 | * | |
3070 | * When the context is determined, the corresponding bit is | |
3071 | * checked and set (if it was set, then a recursion of that context | |
3072 | * happened). | |
3073 | * | |
3074 | * On unlock, we need to clear this bit. To do so, just subtract | |
3075 | * 1 from the current_context and AND it to itself. | |
3076 | * | |
3077 | * (binary) | |
3078 | * 101 - 1 = 100 | |
3079 | * 101 & 100 = 100 (clearing bit zero) | |
3080 | * | |
3081 | * 1010 - 1 = 1001 | |
3082 | * 1010 & 1001 = 1000 (clearing bit 1) | |
3083 | * | |
3084 | * The least significant bit can be cleared this way, and it | |
3085 | * just so happens that it is the same bit corresponding to | |
3086 | * the current context. | |
b02414c8 SRV |
3087 | * |
3088 | * Now the TRANSITION bit breaks the above slightly. The TRANSITION bit | |
3089 | * is set when a recursion is detected at the current context, and if | |
3090 | * the TRANSITION bit is already set, it will fail the recursion. | |
3091 | * This is needed because there's a lag between the changing of | |
3092 | * interrupt context and updating the preempt count. In this case, | |
3093 | * a false positive will be found. To handle this, one extra recursion | |
3094 | * is allowed, and this is done by the TRANSITION bit. If the TRANSITION | |
3095 | * bit is already set, then it is considered a recursion and the function | |
3096 | * ends. Otherwise, the TRANSITION bit is set, and that bit is returned. | |
3097 | * | |
3098 | * On the trace_recursive_unlock(), the TRANSITION bit will be the first | |
3099 | * to be cleared. Even if it wasn't the context that set it. That is, | |
3100 | * if an interrupt comes in while NORMAL bit is set and the ring buffer | |
3101 | * is called before preempt_count() is updated, since the check will | |
3102 | * be on the NORMAL bit, the TRANSITION bit will then be set. If an | |
3103 | * NMI then comes in, it will set the NMI bit, but when the NMI code | |
f2cc020d | 3104 | * does the trace_recursive_unlock() it will clear the TRANSITION bit |
b02414c8 SRV |
3105 | * and leave the NMI bit set. But this is fine, because the interrupt |
3106 | * code that set the TRANSITION bit will then clear the NMI bit when it | |
3107 | * calls trace_recursive_unlock(). If another NMI comes in, it will | |
3108 | * set the TRANSITION bit and continue. | |
3109 | * | |
3110 | * Note: The TRANSITION bit only handles a single transition between context. | |
d90fd774 SRRH |
3111 | */ |
3112 | ||
bc92b956 | 3113 | static __always_inline bool |
d90fd774 SRRH |
3114 | trace_recursive_lock(struct ring_buffer_per_cpu *cpu_buffer) |
3115 | { | |
a0e3a18f | 3116 | unsigned int val = cpu_buffer->current_context; |
91ebe8bc | 3117 | int bit = interrupt_context_level(); |
9b84fadc SRV |
3118 | |
3119 | bit = RB_CTX_NORMAL - bit; | |
a0e3a18f | 3120 | |
b02414c8 SRV |
3121 | if (unlikely(val & (1 << (bit + cpu_buffer->nest)))) { |
3122 | /* | |
3123 | * It is possible that this was called by transitioning | |
3124 | * between interrupt context, and preempt_count() has not | |
3125 | * been updated yet. In this case, use the TRANSITION bit. | |
3126 | */ | |
3127 | bit = RB_CTX_TRANSITION; | |
28575c61 SRV |
3128 | if (val & (1 << (bit + cpu_buffer->nest))) { |
3129 | do_ring_buffer_record_recursion(); | |
bc92b956 | 3130 | return true; |
28575c61 | 3131 | } |
b02414c8 | 3132 | } |
d90fd774 | 3133 | |
8e012066 | 3134 | val |= (1 << (bit + cpu_buffer->nest)); |
a0e3a18f | 3135 | cpu_buffer->current_context = val; |
d90fd774 | 3136 | |
bc92b956 | 3137 | return false; |
d90fd774 SRRH |
3138 | } |
3139 | ||
3140 | static __always_inline void | |
3141 | trace_recursive_unlock(struct ring_buffer_per_cpu *cpu_buffer) | |
3142 | { | |
8e012066 SRV |
3143 | cpu_buffer->current_context &= |
3144 | cpu_buffer->current_context - (1 << cpu_buffer->nest); | |
3145 | } | |
3146 | ||
b02414c8 SRV |
3147 | /* The recursive locking above uses 5 bits */ |
3148 | #define NESTED_BITS 5 | |
8e012066 SRV |
3149 | |
3150 | /** | |
3151 | * ring_buffer_nest_start - Allow to trace while nested | |
3152 | * @buffer: The ring buffer to modify | |
3153 | * | |
6167c205 | 3154 | * The ring buffer has a safety mechanism to prevent recursion. |
8e012066 SRV |
3155 | * But there may be a case where a trace needs to be done while |
3156 | * tracing something else. In this case, calling this function | |
3157 | * will allow this function to nest within a currently active | |
3158 | * ring_buffer_lock_reserve(). | |
3159 | * | |
3160 | * Call this function before calling another ring_buffer_lock_reserve() and | |
3161 | * call ring_buffer_nest_end() after the nested ring_buffer_unlock_commit(). | |
3162 | */ | |
13292494 | 3163 | void ring_buffer_nest_start(struct trace_buffer *buffer) |
8e012066 SRV |
3164 | { |
3165 | struct ring_buffer_per_cpu *cpu_buffer; | |
3166 | int cpu; | |
3167 | ||
3168 | /* Enabled by ring_buffer_nest_end() */ | |
3169 | preempt_disable_notrace(); | |
3170 | cpu = raw_smp_processor_id(); | |
3171 | cpu_buffer = buffer->buffers[cpu]; | |
6167c205 | 3172 | /* This is the shift value for the above recursive locking */ |
8e012066 SRV |
3173 | cpu_buffer->nest += NESTED_BITS; |
3174 | } | |
3175 | ||
3176 | /** | |
3177 | * ring_buffer_nest_end - Allow to trace while nested | |
3178 | * @buffer: The ring buffer to modify | |
3179 | * | |
3180 | * Must be called after ring_buffer_nest_start() and after the | |
3181 | * ring_buffer_unlock_commit(). | |
3182 | */ | |
13292494 | 3183 | void ring_buffer_nest_end(struct trace_buffer *buffer) |
8e012066 SRV |
3184 | { |
3185 | struct ring_buffer_per_cpu *cpu_buffer; | |
3186 | int cpu; | |
3187 | ||
3188 | /* disabled by ring_buffer_nest_start() */ | |
3189 | cpu = raw_smp_processor_id(); | |
3190 | cpu_buffer = buffer->buffers[cpu]; | |
6167c205 | 3191 | /* This is the shift value for the above recursive locking */ |
8e012066 SRV |
3192 | cpu_buffer->nest -= NESTED_BITS; |
3193 | preempt_enable_notrace(); | |
d90fd774 SRRH |
3194 | } |
3195 | ||
3196 | /** | |
3197 | * ring_buffer_unlock_commit - commit a reserved | |
3198 | * @buffer: The buffer to commit to | |
d90fd774 SRRH |
3199 | * |
3200 | * This commits the data to the ring buffer, and releases any locks held. | |
3201 | * | |
3202 | * Must be paired with ring_buffer_lock_reserve. | |
3203 | */ | |
04aabc32 | 3204 | int ring_buffer_unlock_commit(struct trace_buffer *buffer) |
d90fd774 SRRH |
3205 | { |
3206 | struct ring_buffer_per_cpu *cpu_buffer; | |
3207 | int cpu = raw_smp_processor_id(); | |
3208 | ||
3209 | cpu_buffer = buffer->buffers[cpu]; | |
3210 | ||
04aabc32 | 3211 | rb_commit(cpu_buffer); |
d90fd774 SRRH |
3212 | |
3213 | rb_wakeups(buffer, cpu_buffer); | |
3214 | ||
3215 | trace_recursive_unlock(cpu_buffer); | |
3216 | ||
3217 | preempt_enable_notrace(); | |
3218 | ||
3219 | return 0; | |
3220 | } | |
3221 | EXPORT_SYMBOL_GPL(ring_buffer_unlock_commit); | |
3222 | ||
5b7be9c7 SRV |
3223 | /* Special value to validate all deltas on a page. */ |
3224 | #define CHECK_FULL_PAGE 1L | |
3225 | ||
3226 | #ifdef CONFIG_RING_BUFFER_VALIDATE_TIME_DELTAS | |
d40dbb61 SRG |
3227 | |
3228 | static const char *show_irq_str(int bits) | |
3229 | { | |
3230 | const char *type[] = { | |
3231 | ".", // 0 | |
3232 | "s", // 1 | |
3233 | "h", // 2 | |
3234 | "Hs", // 3 | |
3235 | "n", // 4 | |
3236 | "Ns", // 5 | |
3237 | "Nh", // 6 | |
3238 | "NHs", // 7 | |
3239 | }; | |
3240 | ||
3241 | return type[bits]; | |
3242 | } | |
3243 | ||
3244 | /* Assume this is an trace event */ | |
3245 | static const char *show_flags(struct ring_buffer_event *event) | |
3246 | { | |
3247 | struct trace_entry *entry; | |
3248 | int bits = 0; | |
3249 | ||
3250 | if (rb_event_data_length(event) - RB_EVNT_HDR_SIZE < sizeof(*entry)) | |
3251 | return "X"; | |
3252 | ||
3253 | entry = ring_buffer_event_data(event); | |
3254 | ||
3255 | if (entry->flags & TRACE_FLAG_SOFTIRQ) | |
3256 | bits |= 1; | |
3257 | ||
3258 | if (entry->flags & TRACE_FLAG_HARDIRQ) | |
3259 | bits |= 2; | |
3260 | ||
3261 | if (entry->flags & TRACE_FLAG_NMI) | |
3262 | bits |= 4; | |
3263 | ||
3264 | return show_irq_str(bits); | |
3265 | } | |
3266 | ||
3267 | static const char *show_irq(struct ring_buffer_event *event) | |
3268 | { | |
3269 | struct trace_entry *entry; | |
3270 | ||
3271 | if (rb_event_data_length(event) - RB_EVNT_HDR_SIZE < sizeof(*entry)) | |
3272 | return ""; | |
3273 | ||
3274 | entry = ring_buffer_event_data(event); | |
3275 | if (entry->flags & TRACE_FLAG_IRQS_OFF) | |
3276 | return "d"; | |
3277 | return ""; | |
3278 | } | |
3279 | ||
3280 | static const char *show_interrupt_level(void) | |
3281 | { | |
3282 | unsigned long pc = preempt_count(); | |
3283 | unsigned char level = 0; | |
3284 | ||
3285 | if (pc & SOFTIRQ_OFFSET) | |
3286 | level |= 1; | |
3287 | ||
3288 | if (pc & HARDIRQ_MASK) | |
3289 | level |= 2; | |
3290 | ||
3291 | if (pc & NMI_MASK) | |
3292 | level |= 4; | |
3293 | ||
3294 | return show_irq_str(level); | |
3295 | } | |
3296 | ||
5b7be9c7 SRV |
3297 | static void dump_buffer_page(struct buffer_data_page *bpage, |
3298 | struct rb_event_info *info, | |
3299 | unsigned long tail) | |
3300 | { | |
3301 | struct ring_buffer_event *event; | |
3302 | u64 ts, delta; | |
3303 | int e; | |
3304 | ||
3305 | ts = bpage->time_stamp; | |
3306 | pr_warn(" [%lld] PAGE TIME STAMP\n", ts); | |
3307 | ||
3308 | for (e = 0; e < tail; e += rb_event_length(event)) { | |
3309 | ||
3310 | event = (struct ring_buffer_event *)(bpage->data + e); | |
3311 | ||
3312 | switch (event->type_len) { | |
3313 | ||
3314 | case RINGBUF_TYPE_TIME_EXTEND: | |
e20044f7 | 3315 | delta = rb_event_time_stamp(event); |
5b7be9c7 | 3316 | ts += delta; |
0b9036ef SRG |
3317 | pr_warn(" 0x%x: [%lld] delta:%lld TIME EXTEND\n", |
3318 | e, ts, delta); | |
5b7be9c7 SRV |
3319 | break; |
3320 | ||
3321 | case RINGBUF_TYPE_TIME_STAMP: | |
e20044f7 | 3322 | delta = rb_event_time_stamp(event); |
6695da58 | 3323 | ts = rb_fix_abs_ts(delta, ts); |
0b9036ef SRG |
3324 | pr_warn(" 0x%x: [%lld] absolute:%lld TIME STAMP\n", |
3325 | e, ts, delta); | |
5b7be9c7 SRV |
3326 | break; |
3327 | ||
3328 | case RINGBUF_TYPE_PADDING: | |
3329 | ts += event->time_delta; | |
0b9036ef SRG |
3330 | pr_warn(" 0x%x: [%lld] delta:%d PADDING\n", |
3331 | e, ts, event->time_delta); | |
5b7be9c7 SRV |
3332 | break; |
3333 | ||
3334 | case RINGBUF_TYPE_DATA: | |
3335 | ts += event->time_delta; | |
d40dbb61 SRG |
3336 | pr_warn(" 0x%x: [%lld] delta:%d %s%s\n", |
3337 | e, ts, event->time_delta, | |
3338 | show_flags(event), show_irq(event)); | |
5b7be9c7 SRV |
3339 | break; |
3340 | ||
3341 | default: | |
3342 | break; | |
3343 | } | |
3344 | } | |
0b9036ef | 3345 | pr_warn("expected end:0x%lx last event actually ended at:0x%x\n", tail, e); |
5b7be9c7 SRV |
3346 | } |
3347 | ||
3348 | static DEFINE_PER_CPU(atomic_t, checking); | |
3349 | static atomic_t ts_dump; | |
3350 | ||
f50345b4 SRG |
3351 | #define buffer_warn_return(fmt, ...) \ |
3352 | do { \ | |
3353 | /* If another report is happening, ignore this one */ \ | |
3354 | if (atomic_inc_return(&ts_dump) != 1) { \ | |
3355 | atomic_dec(&ts_dump); \ | |
3356 | goto out; \ | |
3357 | } \ | |
3358 | atomic_inc(&cpu_buffer->record_disabled); \ | |
3359 | pr_warn(fmt, ##__VA_ARGS__); \ | |
3360 | dump_buffer_page(bpage, info, tail); \ | |
3361 | atomic_dec(&ts_dump); \ | |
3362 | /* There's some cases in boot up that this can happen */ \ | |
3363 | if (WARN_ON_ONCE(system_state != SYSTEM_BOOTING)) \ | |
3364 | /* Do not re-enable checking */ \ | |
3365 | return; \ | |
3366 | } while (0) | |
3367 | ||
5b7be9c7 SRV |
3368 | /* |
3369 | * Check if the current event time stamp matches the deltas on | |
3370 | * the buffer page. | |
3371 | */ | |
3372 | static void check_buffer(struct ring_buffer_per_cpu *cpu_buffer, | |
3373 | struct rb_event_info *info, | |
3374 | unsigned long tail) | |
3375 | { | |
3376 | struct ring_buffer_event *event; | |
3377 | struct buffer_data_page *bpage; | |
3378 | u64 ts, delta; | |
3379 | bool full = false; | |
3380 | int e; | |
3381 | ||
3382 | bpage = info->tail_page->page; | |
3383 | ||
3384 | if (tail == CHECK_FULL_PAGE) { | |
3385 | full = true; | |
3386 | tail = local_read(&bpage->commit); | |
3387 | } else if (info->add_timestamp & | |
3388 | (RB_ADD_STAMP_FORCE | RB_ADD_STAMP_ABSOLUTE)) { | |
3389 | /* Ignore events with absolute time stamps */ | |
3390 | return; | |
3391 | } | |
3392 | ||
3393 | /* | |
3394 | * Do not check the first event (skip possible extends too). | |
3395 | * Also do not check if previous events have not been committed. | |
3396 | */ | |
3397 | if (tail <= 8 || tail > local_read(&bpage->commit)) | |
3398 | return; | |
3399 | ||
3400 | /* | |
083e9f65 | 3401 | * If this interrupted another event, |
5b7be9c7 SRV |
3402 | */ |
3403 | if (atomic_inc_return(this_cpu_ptr(&checking)) != 1) | |
3404 | goto out; | |
3405 | ||
3406 | ts = bpage->time_stamp; | |
3407 | ||
3408 | for (e = 0; e < tail; e += rb_event_length(event)) { | |
3409 | ||
3410 | event = (struct ring_buffer_event *)(bpage->data + e); | |
3411 | ||
3412 | switch (event->type_len) { | |
3413 | ||
3414 | case RINGBUF_TYPE_TIME_EXTEND: | |
e20044f7 | 3415 | delta = rb_event_time_stamp(event); |
5b7be9c7 SRV |
3416 | ts += delta; |
3417 | break; | |
3418 | ||
3419 | case RINGBUF_TYPE_TIME_STAMP: | |
e20044f7 | 3420 | delta = rb_event_time_stamp(event); |
f50345b4 SRG |
3421 | delta = rb_fix_abs_ts(delta, ts); |
3422 | if (delta < ts) { | |
3423 | buffer_warn_return("[CPU: %d]ABSOLUTE TIME WENT BACKWARDS: last ts: %lld absolute ts: %lld\n", | |
3424 | cpu_buffer->cpu, ts, delta); | |
3425 | } | |
3426 | ts = delta; | |
5b7be9c7 SRV |
3427 | break; |
3428 | ||
3429 | case RINGBUF_TYPE_PADDING: | |
3430 | if (event->time_delta == 1) | |
3431 | break; | |
957cdcd9 | 3432 | fallthrough; |
5b7be9c7 SRV |
3433 | case RINGBUF_TYPE_DATA: |
3434 | ts += event->time_delta; | |
3435 | break; | |
3436 | ||
3437 | default: | |
3438 | RB_WARN_ON(cpu_buffer, 1); | |
3439 | } | |
3440 | } | |
3441 | if ((full && ts > info->ts) || | |
3442 | (!full && ts + info->delta != info->ts)) { | |
f50345b4 SRG |
3443 | buffer_warn_return("[CPU: %d]TIME DOES NOT MATCH expected:%lld actual:%lld delta:%lld before:%lld after:%lld%s context:%s\n", |
3444 | cpu_buffer->cpu, | |
3445 | ts + info->delta, info->ts, info->delta, | |
3446 | info->before, info->after, | |
3447 | full ? " (full)" : "", show_interrupt_level()); | |
5b7be9c7 SRV |
3448 | } |
3449 | out: | |
3450 | atomic_dec(this_cpu_ptr(&checking)); | |
3451 | } | |
3452 | #else | |
3453 | static inline void check_buffer(struct ring_buffer_per_cpu *cpu_buffer, | |
3454 | struct rb_event_info *info, | |
3455 | unsigned long tail) | |
3456 | { | |
3457 | } | |
3458 | #endif /* CONFIG_RING_BUFFER_VALIDATE_TIME_DELTAS */ | |
3459 | ||
6634ff26 SR |
3460 | static struct ring_buffer_event * |
3461 | __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, | |
fcc742ea | 3462 | struct rb_event_info *info) |
6634ff26 | 3463 | { |
6634ff26 | 3464 | struct ring_buffer_event *event; |
fcc742ea | 3465 | struct buffer_page *tail_page; |
a389d86f | 3466 | unsigned long tail, write, w; |
69d1b839 | 3467 | |
8573636e SRRH |
3468 | /* Don't let the compiler play games with cpu_buffer->tail_page */ |
3469 | tail_page = info->tail_page = READ_ONCE(cpu_buffer->tail_page); | |
a389d86f SRV |
3470 | |
3471 | /*A*/ w = local_read(&tail_page->write) & RB_WRITE_MASK; | |
3472 | barrier(); | |
c84897c0 SRG |
3473 | rb_time_read(&cpu_buffer->before_stamp, &info->before); |
3474 | rb_time_read(&cpu_buffer->write_stamp, &info->after); | |
a389d86f SRV |
3475 | barrier(); |
3476 | info->ts = rb_time_stamp(cpu_buffer->buffer); | |
3477 | ||
58fbc3c6 | 3478 | if ((info->add_timestamp & RB_ADD_STAMP_ABSOLUTE)) { |
a389d86f | 3479 | info->delta = info->ts; |
a389d86f | 3480 | } else { |
58fbc3c6 SRV |
3481 | /* |
3482 | * If interrupting an event time update, we may need an | |
3483 | * absolute timestamp. | |
3484 | * Don't bother if this is the start of a new page (w == 0). | |
3485 | */ | |
b3ae7b67 SRG |
3486 | if (!w) { |
3487 | /* Use the sub-buffer timestamp */ | |
3488 | info->delta = 0; | |
c84897c0 | 3489 | } else if (unlikely(info->before != info->after)) { |
58fbc3c6 SRV |
3490 | info->add_timestamp |= RB_ADD_STAMP_FORCE | RB_ADD_STAMP_EXTEND; |
3491 | info->length += RB_LEN_TIME_EXTEND; | |
3492 | } else { | |
3493 | info->delta = info->ts - info->after; | |
3494 | if (unlikely(test_time_stamp(info->delta))) { | |
3495 | info->add_timestamp |= RB_ADD_STAMP_EXTEND; | |
3496 | info->length += RB_LEN_TIME_EXTEND; | |
3497 | } | |
10464b4a | 3498 | } |
7c4b4a51 | 3499 | } |
b7dc42fd | 3500 | |
10464b4a | 3501 | /*B*/ rb_time_set(&cpu_buffer->before_stamp, info->ts); |
a389d86f SRV |
3502 | |
3503 | /*C*/ write = local_add_return(info->length, &tail_page->write); | |
77ae365e SR |
3504 | |
3505 | /* set write to only the index of the write */ | |
3506 | write &= RB_WRITE_MASK; | |
a389d86f | 3507 | |
fcc742ea | 3508 | tail = write - info->length; |
6634ff26 | 3509 | |
a389d86f | 3510 | /* See if we shot pass the end of this buffer page */ |
139f8400 | 3511 | if (unlikely(write > cpu_buffer->buffer->subbuf_size)) { |
9e45e39d | 3512 | check_buffer(cpu_buffer, info, CHECK_FULL_PAGE); |
a389d86f SRV |
3513 | return rb_move_tail(cpu_buffer, tail, info); |
3514 | } | |
3515 | ||
3516 | if (likely(tail == w)) { | |
a389d86f | 3517 | /* Nothing interrupted us between A and C */ |
10464b4a | 3518 | /*D*/ rb_time_set(&cpu_buffer->write_stamp, info->ts); |
dd939425 SRG |
3519 | /* |
3520 | * If something came in between C and D, the write stamp | |
3521 | * may now not be in sync. But that's fine as the before_stamp | |
3522 | * will be different and then next event will just be forced | |
3523 | * to use an absolute timestamp. | |
3524 | */ | |
7c4b4a51 SRV |
3525 | if (likely(!(info->add_timestamp & |
3526 | (RB_ADD_STAMP_FORCE | RB_ADD_STAMP_ABSOLUTE)))) | |
a389d86f | 3527 | /* This did not interrupt any time update */ |
58fbc3c6 | 3528 | info->delta = info->ts - info->after; |
a389d86f | 3529 | else |
82db909e | 3530 | /* Just use full timestamp for interrupting event */ |
a389d86f | 3531 | info->delta = info->ts; |
5b7be9c7 | 3532 | check_buffer(cpu_buffer, info, tail); |
a389d86f SRV |
3533 | } else { |
3534 | u64 ts; | |
3535 | /* SLOW PATH - Interrupted between A and C */ | |
b803d7c6 SRG |
3536 | |
3537 | /* Save the old before_stamp */ | |
c84897c0 | 3538 | rb_time_read(&cpu_buffer->before_stamp, &info->before); |
b803d7c6 SRG |
3539 | |
3540 | /* | |
3541 | * Read a new timestamp and update the before_stamp to make | |
3542 | * the next event after this one force using an absolute | |
3543 | * timestamp. This is in case an interrupt were to come in | |
3544 | * between E and F. | |
3545 | */ | |
a389d86f | 3546 | ts = rb_time_stamp(cpu_buffer->buffer); |
b803d7c6 SRG |
3547 | rb_time_set(&cpu_buffer->before_stamp, ts); |
3548 | ||
3549 | barrier(); | |
c84897c0 | 3550 | /*E*/ rb_time_read(&cpu_buffer->write_stamp, &info->after); |
a389d86f | 3551 | barrier(); |
b803d7c6 SRG |
3552 | /*F*/ if (write == (local_read(&tail_page->write) & RB_WRITE_MASK) && |
3553 | info->after == info->before && info->after < ts) { | |
3554 | /* | |
3555 | * Nothing came after this event between C and F, it is | |
3556 | * safe to use info->after for the delta as it | |
3557 | * matched info->before and is still valid. | |
3558 | */ | |
58fbc3c6 | 3559 | info->delta = ts - info->after; |
a389d86f SRV |
3560 | } else { |
3561 | /* | |
b803d7c6 | 3562 | * Interrupted between C and F: |
a389d86f SRV |
3563 | * Lost the previous events time stamp. Just set the |
3564 | * delta to zero, and this will be the same time as | |
3565 | * the event this event interrupted. And the events that | |
3566 | * came after this will still be correct (as they would | |
3567 | * have built their delta on the previous event. | |
3568 | */ | |
3569 | info->delta = 0; | |
3570 | } | |
8672e494 | 3571 | info->ts = ts; |
7c4b4a51 | 3572 | info->add_timestamp &= ~RB_ADD_STAMP_FORCE; |
a389d86f SRV |
3573 | } |
3574 | ||
6634ff26 | 3575 | /* |
a4543a2f | 3576 | * If this is the first commit on the page, then it has the same |
b7dc42fd | 3577 | * timestamp as the page itself. |
6634ff26 | 3578 | */ |
7c4b4a51 SRV |
3579 | if (unlikely(!tail && !(info->add_timestamp & |
3580 | (RB_ADD_STAMP_FORCE | RB_ADD_STAMP_ABSOLUTE)))) | |
a4543a2f SRRH |
3581 | info->delta = 0; |
3582 | ||
b7dc42fd SRRH |
3583 | /* We reserved something on the buffer */ |
3584 | ||
3585 | event = __rb_page_index(tail_page, tail); | |
a4543a2f SRRH |
3586 | rb_update_event(cpu_buffer, event, info); |
3587 | ||
3588 | local_inc(&tail_page->entries); | |
6634ff26 | 3589 | |
b7dc42fd SRRH |
3590 | /* |
3591 | * If this is the first commit on the page, then update | |
3592 | * its timestamp. | |
3593 | */ | |
75b21c6d | 3594 | if (unlikely(!tail)) |
b7dc42fd SRRH |
3595 | tail_page->page->time_stamp = info->ts; |
3596 | ||
c64e148a | 3597 | /* account for these added bytes */ |
fcc742ea | 3598 | local_add(info->length, &cpu_buffer->entries_bytes); |
c64e148a | 3599 | |
6634ff26 SR |
3600 | return event; |
3601 | } | |
3602 | ||
fa7ffb39 | 3603 | static __always_inline struct ring_buffer_event * |
13292494 | 3604 | rb_reserve_next_event(struct trace_buffer *buffer, |
62f0b3eb | 3605 | struct ring_buffer_per_cpu *cpu_buffer, |
1cd8d735 | 3606 | unsigned long length) |
7a8e76a3 SR |
3607 | { |
3608 | struct ring_buffer_event *event; | |
fcc742ea | 3609 | struct rb_event_info info; |
818e3dd3 | 3610 | int nr_loops = 0; |
58fbc3c6 | 3611 | int add_ts_default; |
7a8e76a3 | 3612 | |
71229230 SRG |
3613 | /* ring buffer does cmpxchg, make sure it is safe in NMI context */ |
3614 | if (!IS_ENABLED(CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG) && | |
3615 | (unlikely(in_nmi()))) { | |
3616 | return NULL; | |
3617 | } | |
3618 | ||
fa743953 | 3619 | rb_start_commit(cpu_buffer); |
a389d86f | 3620 | /* The commit page can not change after this */ |
fa743953 | 3621 | |
85bac32c | 3622 | #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP |
62f0b3eb SR |
3623 | /* |
3624 | * Due to the ability to swap a cpu buffer from a buffer | |
3625 | * it is possible it was swapped before we committed. | |
3626 | * (committing stops a swap). We check for it here and | |
3627 | * if it happened, we have to fail the write. | |
3628 | */ | |
3629 | barrier(); | |
6aa7de05 | 3630 | if (unlikely(READ_ONCE(cpu_buffer->buffer) != buffer)) { |
62f0b3eb SR |
3631 | local_dec(&cpu_buffer->committing); |
3632 | local_dec(&cpu_buffer->commits); | |
3633 | return NULL; | |
3634 | } | |
85bac32c | 3635 | #endif |
b7dc42fd | 3636 | |
fcc742ea | 3637 | info.length = rb_calculate_event_length(length); |
58fbc3c6 SRV |
3638 | |
3639 | if (ring_buffer_time_stamp_abs(cpu_buffer->buffer)) { | |
3640 | add_ts_default = RB_ADD_STAMP_ABSOLUTE; | |
3641 | info.length += RB_LEN_TIME_EXTEND; | |
139f8400 | 3642 | if (info.length > cpu_buffer->buffer->max_data_size) |
b3ae7b67 | 3643 | goto out_fail; |
58fbc3c6 SRV |
3644 | } else { |
3645 | add_ts_default = RB_ADD_STAMP_NONE; | |
3646 | } | |
3647 | ||
a4543a2f | 3648 | again: |
58fbc3c6 | 3649 | info.add_timestamp = add_ts_default; |
b7dc42fd SRRH |
3650 | info.delta = 0; |
3651 | ||
818e3dd3 SR |
3652 | /* |
3653 | * We allow for interrupts to reenter here and do a trace. | |
3654 | * If one does, it will cause this original code to loop | |
3655 | * back here. Even with heavy interrupts happening, this | |
3656 | * should only happen a few times in a row. If this happens | |
3657 | * 1000 times in a row, there must be either an interrupt | |
3658 | * storm or we have something buggy. | |
3659 | * Bail! | |
3660 | */ | |
3e89c7bb | 3661 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000)) |
fa743953 | 3662 | goto out_fail; |
818e3dd3 | 3663 | |
fcc742ea SRRH |
3664 | event = __rb_reserve_next(cpu_buffer, &info); |
3665 | ||
bd1b7cd3 | 3666 | if (unlikely(PTR_ERR(event) == -EAGAIN)) { |
58fbc3c6 | 3667 | if (info.add_timestamp & (RB_ADD_STAMP_FORCE | RB_ADD_STAMP_EXTEND)) |
bd1b7cd3 | 3668 | info.length -= RB_LEN_TIME_EXTEND; |
bf41a158 | 3669 | goto again; |
bd1b7cd3 | 3670 | } |
bf41a158 | 3671 | |
a389d86f SRV |
3672 | if (likely(event)) |
3673 | return event; | |
fa743953 SR |
3674 | out_fail: |
3675 | rb_end_commit(cpu_buffer); | |
3676 | return NULL; | |
7a8e76a3 SR |
3677 | } |
3678 | ||
3679 | /** | |
3680 | * ring_buffer_lock_reserve - reserve a part of the buffer | |
3681 | * @buffer: the ring buffer to reserve from | |
3682 | * @length: the length of the data to reserve (excluding event header) | |
7a8e76a3 | 3683 | * |
6167c205 | 3684 | * Returns a reserved event on the ring buffer to copy directly to. |
7a8e76a3 SR |
3685 | * The user of this interface will need to get the body to write into |
3686 | * and can use the ring_buffer_event_data() interface. | |
3687 | * | |
3688 | * The length is the length of the data needed, not the event length | |
3689 | * which also includes the event header. | |
3690 | * | |
3691 | * Must be paired with ring_buffer_unlock_commit, unless NULL is returned. | |
3692 | * If NULL is returned, then nothing has been allocated or locked. | |
3693 | */ | |
3694 | struct ring_buffer_event * | |
13292494 | 3695 | ring_buffer_lock_reserve(struct trace_buffer *buffer, unsigned long length) |
7a8e76a3 SR |
3696 | { |
3697 | struct ring_buffer_per_cpu *cpu_buffer; | |
3698 | struct ring_buffer_event *event; | |
5168ae50 | 3699 | int cpu; |
7a8e76a3 | 3700 | |
bf41a158 | 3701 | /* If we are tracing schedule, we don't want to recurse */ |
5168ae50 | 3702 | preempt_disable_notrace(); |
bf41a158 | 3703 | |
3205f806 | 3704 | if (unlikely(atomic_read(&buffer->record_disabled))) |
58a09ec6 | 3705 | goto out; |
261842b7 | 3706 | |
7a8e76a3 SR |
3707 | cpu = raw_smp_processor_id(); |
3708 | ||
3205f806 | 3709 | if (unlikely(!cpumask_test_cpu(cpu, buffer->cpumask))) |
d769041f | 3710 | goto out; |
7a8e76a3 SR |
3711 | |
3712 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 | 3713 | |
3205f806 | 3714 | if (unlikely(atomic_read(&cpu_buffer->record_disabled))) |
d769041f | 3715 | goto out; |
7a8e76a3 | 3716 | |
139f8400 | 3717 | if (unlikely(length > buffer->max_data_size)) |
bf41a158 | 3718 | goto out; |
7a8e76a3 | 3719 | |
58a09ec6 SRRH |
3720 | if (unlikely(trace_recursive_lock(cpu_buffer))) |
3721 | goto out; | |
3722 | ||
62f0b3eb | 3723 | event = rb_reserve_next_event(buffer, cpu_buffer, length); |
7a8e76a3 | 3724 | if (!event) |
58a09ec6 | 3725 | goto out_unlock; |
7a8e76a3 SR |
3726 | |
3727 | return event; | |
3728 | ||
58a09ec6 SRRH |
3729 | out_unlock: |
3730 | trace_recursive_unlock(cpu_buffer); | |
d769041f | 3731 | out: |
5168ae50 | 3732 | preempt_enable_notrace(); |
7a8e76a3 SR |
3733 | return NULL; |
3734 | } | |
c4f50183 | 3735 | EXPORT_SYMBOL_GPL(ring_buffer_lock_reserve); |
7a8e76a3 | 3736 | |
a1863c21 SR |
3737 | /* |
3738 | * Decrement the entries to the page that an event is on. | |
3739 | * The event does not even need to exist, only the pointer | |
3740 | * to the page it is on. This may only be called before the commit | |
3741 | * takes place. | |
3742 | */ | |
3743 | static inline void | |
3744 | rb_decrement_entry(struct ring_buffer_per_cpu *cpu_buffer, | |
3745 | struct ring_buffer_event *event) | |
3746 | { | |
3747 | unsigned long addr = (unsigned long)event; | |
3748 | struct buffer_page *bpage = cpu_buffer->commit_page; | |
3749 | struct buffer_page *start; | |
3750 | ||
3cb30911 | 3751 | addr &= ~((PAGE_SIZE << cpu_buffer->buffer->subbuf_order) - 1); |
a1863c21 SR |
3752 | |
3753 | /* Do the likely case first */ | |
3754 | if (likely(bpage->page == (void *)addr)) { | |
3755 | local_dec(&bpage->entries); | |
3756 | return; | |
3757 | } | |
3758 | ||
3759 | /* | |
3760 | * Because the commit page may be on the reader page we | |
3761 | * start with the next page and check the end loop there. | |
3762 | */ | |
6689bed3 | 3763 | rb_inc_page(&bpage); |
a1863c21 SR |
3764 | start = bpage; |
3765 | do { | |
3766 | if (bpage->page == (void *)addr) { | |
3767 | local_dec(&bpage->entries); | |
3768 | return; | |
3769 | } | |
6689bed3 | 3770 | rb_inc_page(&bpage); |
a1863c21 SR |
3771 | } while (bpage != start); |
3772 | ||
3773 | /* commit not part of this buffer?? */ | |
3774 | RB_WARN_ON(cpu_buffer, 1); | |
3775 | } | |
3776 | ||
fa1b47dd | 3777 | /** |
88883490 | 3778 | * ring_buffer_discard_commit - discard an event that has not been committed |
fa1b47dd SR |
3779 | * @buffer: the ring buffer |
3780 | * @event: non committed event to discard | |
3781 | * | |
dc892f73 SR |
3782 | * Sometimes an event that is in the ring buffer needs to be ignored. |
3783 | * This function lets the user discard an event in the ring buffer | |
3784 | * and then that event will not be read later. | |
3785 | * | |
6167c205 | 3786 | * This function only works if it is called before the item has been |
dc892f73 | 3787 | * committed. It will try to free the event from the ring buffer |
fa1b47dd SR |
3788 | * if another event has not been added behind it. |
3789 | * | |
3790 | * If another event has been added behind it, it will set the event | |
3791 | * up as discarded, and perform the commit. | |
3792 | * | |
3793 | * If this function is called, do not call ring_buffer_unlock_commit on | |
3794 | * the event. | |
3795 | */ | |
13292494 | 3796 | void ring_buffer_discard_commit(struct trace_buffer *buffer, |
fa1b47dd SR |
3797 | struct ring_buffer_event *event) |
3798 | { | |
3799 | struct ring_buffer_per_cpu *cpu_buffer; | |
fa1b47dd SR |
3800 | int cpu; |
3801 | ||
3802 | /* The event is discarded regardless */ | |
f3b9aae1 | 3803 | rb_event_discard(event); |
fa1b47dd | 3804 | |
fa743953 SR |
3805 | cpu = smp_processor_id(); |
3806 | cpu_buffer = buffer->buffers[cpu]; | |
3807 | ||
fa1b47dd SR |
3808 | /* |
3809 | * This must only be called if the event has not been | |
3810 | * committed yet. Thus we can assume that preemption | |
3811 | * is still disabled. | |
3812 | */ | |
fa743953 | 3813 | RB_WARN_ON(buffer, !local_read(&cpu_buffer->committing)); |
fa1b47dd | 3814 | |
a1863c21 | 3815 | rb_decrement_entry(cpu_buffer, event); |
0f2541d2 | 3816 | if (rb_try_to_discard(cpu_buffer, event)) |
edd813bf | 3817 | goto out; |
fa1b47dd | 3818 | |
fa1b47dd | 3819 | out: |
fa743953 | 3820 | rb_end_commit(cpu_buffer); |
fa1b47dd | 3821 | |
58a09ec6 | 3822 | trace_recursive_unlock(cpu_buffer); |
f3b9aae1 | 3823 | |
5168ae50 | 3824 | preempt_enable_notrace(); |
fa1b47dd SR |
3825 | |
3826 | } | |
3827 | EXPORT_SYMBOL_GPL(ring_buffer_discard_commit); | |
3828 | ||
7a8e76a3 SR |
3829 | /** |
3830 | * ring_buffer_write - write data to the buffer without reserving | |
3831 | * @buffer: The ring buffer to write to. | |
3832 | * @length: The length of the data being written (excluding the event header) | |
3833 | * @data: The data to write to the buffer. | |
3834 | * | |
3835 | * This is like ring_buffer_lock_reserve and ring_buffer_unlock_commit as | |
3836 | * one function. If you already have the data to write to the buffer, it | |
3837 | * may be easier to simply call this function. | |
3838 | * | |
3839 | * Note, like ring_buffer_lock_reserve, the length is the length of the data | |
3840 | * and not the length of the event which would hold the header. | |
3841 | */ | |
13292494 | 3842 | int ring_buffer_write(struct trace_buffer *buffer, |
01e3e710 DS |
3843 | unsigned long length, |
3844 | void *data) | |
7a8e76a3 SR |
3845 | { |
3846 | struct ring_buffer_per_cpu *cpu_buffer; | |
3847 | struct ring_buffer_event *event; | |
7a8e76a3 SR |
3848 | void *body; |
3849 | int ret = -EBUSY; | |
5168ae50 | 3850 | int cpu; |
7a8e76a3 | 3851 | |
5168ae50 | 3852 | preempt_disable_notrace(); |
bf41a158 | 3853 | |
52fbe9cd LJ |
3854 | if (atomic_read(&buffer->record_disabled)) |
3855 | goto out; | |
3856 | ||
7a8e76a3 SR |
3857 | cpu = raw_smp_processor_id(); |
3858 | ||
9e01c1b7 | 3859 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
d769041f | 3860 | goto out; |
7a8e76a3 SR |
3861 | |
3862 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 SR |
3863 | |
3864 | if (atomic_read(&cpu_buffer->record_disabled)) | |
3865 | goto out; | |
3866 | ||
139f8400 | 3867 | if (length > buffer->max_data_size) |
be957c44 SR |
3868 | goto out; |
3869 | ||
985e871b SRRH |
3870 | if (unlikely(trace_recursive_lock(cpu_buffer))) |
3871 | goto out; | |
3872 | ||
62f0b3eb | 3873 | event = rb_reserve_next_event(buffer, cpu_buffer, length); |
7a8e76a3 | 3874 | if (!event) |
985e871b | 3875 | goto out_unlock; |
7a8e76a3 SR |
3876 | |
3877 | body = rb_event_data(event); | |
3878 | ||
3879 | memcpy(body, data, length); | |
3880 | ||
04aabc32 | 3881 | rb_commit(cpu_buffer); |
7a8e76a3 | 3882 | |
15693458 SRRH |
3883 | rb_wakeups(buffer, cpu_buffer); |
3884 | ||
7a8e76a3 | 3885 | ret = 0; |
985e871b SRRH |
3886 | |
3887 | out_unlock: | |
3888 | trace_recursive_unlock(cpu_buffer); | |
3889 | ||
7a8e76a3 | 3890 | out: |
5168ae50 | 3891 | preempt_enable_notrace(); |
7a8e76a3 SR |
3892 | |
3893 | return ret; | |
3894 | } | |
c4f50183 | 3895 | EXPORT_SYMBOL_GPL(ring_buffer_write); |
7a8e76a3 | 3896 | |
da58834c | 3897 | static bool rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) |
bf41a158 SR |
3898 | { |
3899 | struct buffer_page *reader = cpu_buffer->reader_page; | |
77ae365e | 3900 | struct buffer_page *head = rb_set_head_page(cpu_buffer); |
bf41a158 SR |
3901 | struct buffer_page *commit = cpu_buffer->commit_page; |
3902 | ||
77ae365e SR |
3903 | /* In case of error, head will be NULL */ |
3904 | if (unlikely(!head)) | |
da58834c | 3905 | return true; |
77ae365e | 3906 | |
67f0d6d9 HL |
3907 | /* Reader should exhaust content in reader page */ |
3908 | if (reader->read != rb_page_commit(reader)) | |
3909 | return false; | |
3910 | ||
3911 | /* | |
3912 | * If writers are committing on the reader page, knowing all | |
3913 | * committed content has been read, the ring buffer is empty. | |
3914 | */ | |
3915 | if (commit == reader) | |
3916 | return true; | |
3917 | ||
3918 | /* | |
3919 | * If writers are committing on a page other than reader page | |
3920 | * and head page, there should always be content to read. | |
3921 | */ | |
3922 | if (commit != head) | |
3923 | return false; | |
3924 | ||
3925 | /* | |
3926 | * Writers are committing on the head page, we just need | |
3927 | * to care about there're committed data, and the reader will | |
3928 | * swap reader page with head page when it is to read data. | |
3929 | */ | |
3930 | return rb_page_commit(commit) == 0; | |
bf41a158 SR |
3931 | } |
3932 | ||
7a8e76a3 SR |
3933 | /** |
3934 | * ring_buffer_record_disable - stop all writes into the buffer | |
3935 | * @buffer: The ring buffer to stop writes to. | |
3936 | * | |
3937 | * This prevents all writes to the buffer. Any attempt to write | |
3938 | * to the buffer after this will fail and return NULL. | |
3939 | * | |
74401729 | 3940 | * The caller should call synchronize_rcu() after this. |
7a8e76a3 | 3941 | */ |
13292494 | 3942 | void ring_buffer_record_disable(struct trace_buffer *buffer) |
7a8e76a3 SR |
3943 | { |
3944 | atomic_inc(&buffer->record_disabled); | |
3945 | } | |
c4f50183 | 3946 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable); |
7a8e76a3 SR |
3947 | |
3948 | /** | |
3949 | * ring_buffer_record_enable - enable writes to the buffer | |
3950 | * @buffer: The ring buffer to enable writes | |
3951 | * | |
3952 | * Note, multiple disables will need the same number of enables | |
c41b20e7 | 3953 | * to truly enable the writing (much like preempt_disable). |
7a8e76a3 | 3954 | */ |
13292494 | 3955 | void ring_buffer_record_enable(struct trace_buffer *buffer) |
7a8e76a3 SR |
3956 | { |
3957 | atomic_dec(&buffer->record_disabled); | |
3958 | } | |
c4f50183 | 3959 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable); |
7a8e76a3 | 3960 | |
499e5470 SR |
3961 | /** |
3962 | * ring_buffer_record_off - stop all writes into the buffer | |
3963 | * @buffer: The ring buffer to stop writes to. | |
3964 | * | |
3965 | * This prevents all writes to the buffer. Any attempt to write | |
3966 | * to the buffer after this will fail and return NULL. | |
3967 | * | |
3968 | * This is different than ring_buffer_record_disable() as | |
87abb3b1 | 3969 | * it works like an on/off switch, where as the disable() version |
499e5470 SR |
3970 | * must be paired with a enable(). |
3971 | */ | |
13292494 | 3972 | void ring_buffer_record_off(struct trace_buffer *buffer) |
499e5470 SR |
3973 | { |
3974 | unsigned int rd; | |
3975 | unsigned int new_rd; | |
3976 | ||
8328e36d | 3977 | rd = atomic_read(&buffer->record_disabled); |
499e5470 | 3978 | do { |
499e5470 | 3979 | new_rd = rd | RB_BUFFER_OFF; |
8328e36d | 3980 | } while (!atomic_try_cmpxchg(&buffer->record_disabled, &rd, new_rd)); |
499e5470 SR |
3981 | } |
3982 | EXPORT_SYMBOL_GPL(ring_buffer_record_off); | |
3983 | ||
3984 | /** | |
3985 | * ring_buffer_record_on - restart writes into the buffer | |
3986 | * @buffer: The ring buffer to start writes to. | |
3987 | * | |
3988 | * This enables all writes to the buffer that was disabled by | |
3989 | * ring_buffer_record_off(). | |
3990 | * | |
3991 | * This is different than ring_buffer_record_enable() as | |
87abb3b1 | 3992 | * it works like an on/off switch, where as the enable() version |
499e5470 SR |
3993 | * must be paired with a disable(). |
3994 | */ | |
13292494 | 3995 | void ring_buffer_record_on(struct trace_buffer *buffer) |
499e5470 SR |
3996 | { |
3997 | unsigned int rd; | |
3998 | unsigned int new_rd; | |
3999 | ||
8328e36d | 4000 | rd = atomic_read(&buffer->record_disabled); |
499e5470 | 4001 | do { |
499e5470 | 4002 | new_rd = rd & ~RB_BUFFER_OFF; |
8328e36d | 4003 | } while (!atomic_try_cmpxchg(&buffer->record_disabled, &rd, new_rd)); |
499e5470 SR |
4004 | } |
4005 | EXPORT_SYMBOL_GPL(ring_buffer_record_on); | |
4006 | ||
4007 | /** | |
4008 | * ring_buffer_record_is_on - return true if the ring buffer can write | |
4009 | * @buffer: The ring buffer to see if write is enabled | |
4010 | * | |
4011 | * Returns true if the ring buffer is in a state that it accepts writes. | |
4012 | */ | |
13292494 | 4013 | bool ring_buffer_record_is_on(struct trace_buffer *buffer) |
499e5470 SR |
4014 | { |
4015 | return !atomic_read(&buffer->record_disabled); | |
4016 | } | |
4017 | ||
73c8d894 MH |
4018 | /** |
4019 | * ring_buffer_record_is_set_on - return true if the ring buffer is set writable | |
4020 | * @buffer: The ring buffer to see if write is set enabled | |
4021 | * | |
4022 | * Returns true if the ring buffer is set writable by ring_buffer_record_on(). | |
4023 | * Note that this does NOT mean it is in a writable state. | |
4024 | * | |
4025 | * It may return true when the ring buffer has been disabled by | |
4026 | * ring_buffer_record_disable(), as that is a temporary disabling of | |
4027 | * the ring buffer. | |
4028 | */ | |
13292494 | 4029 | bool ring_buffer_record_is_set_on(struct trace_buffer *buffer) |
73c8d894 MH |
4030 | { |
4031 | return !(atomic_read(&buffer->record_disabled) & RB_BUFFER_OFF); | |
4032 | } | |
4033 | ||
7a8e76a3 SR |
4034 | /** |
4035 | * ring_buffer_record_disable_cpu - stop all writes into the cpu_buffer | |
4036 | * @buffer: The ring buffer to stop writes to. | |
4037 | * @cpu: The CPU buffer to stop | |
4038 | * | |
4039 | * This prevents all writes to the buffer. Any attempt to write | |
4040 | * to the buffer after this will fail and return NULL. | |
4041 | * | |
74401729 | 4042 | * The caller should call synchronize_rcu() after this. |
7a8e76a3 | 4043 | */ |
13292494 | 4044 | void ring_buffer_record_disable_cpu(struct trace_buffer *buffer, int cpu) |
7a8e76a3 SR |
4045 | { |
4046 | struct ring_buffer_per_cpu *cpu_buffer; | |
4047 | ||
9e01c1b7 | 4048 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 4049 | return; |
7a8e76a3 SR |
4050 | |
4051 | cpu_buffer = buffer->buffers[cpu]; | |
4052 | atomic_inc(&cpu_buffer->record_disabled); | |
4053 | } | |
c4f50183 | 4054 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable_cpu); |
7a8e76a3 SR |
4055 | |
4056 | /** | |
4057 | * ring_buffer_record_enable_cpu - enable writes to the buffer | |
4058 | * @buffer: The ring buffer to enable writes | |
4059 | * @cpu: The CPU to enable. | |
4060 | * | |
4061 | * Note, multiple disables will need the same number of enables | |
c41b20e7 | 4062 | * to truly enable the writing (much like preempt_disable). |
7a8e76a3 | 4063 | */ |
13292494 | 4064 | void ring_buffer_record_enable_cpu(struct trace_buffer *buffer, int cpu) |
7a8e76a3 SR |
4065 | { |
4066 | struct ring_buffer_per_cpu *cpu_buffer; | |
4067 | ||
9e01c1b7 | 4068 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 4069 | return; |
7a8e76a3 SR |
4070 | |
4071 | cpu_buffer = buffer->buffers[cpu]; | |
4072 | atomic_dec(&cpu_buffer->record_disabled); | |
4073 | } | |
c4f50183 | 4074 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu); |
7a8e76a3 | 4075 | |
f6195aa0 SR |
4076 | /* |
4077 | * The total entries in the ring buffer is the running counter | |
4078 | * of entries entered into the ring buffer, minus the sum of | |
4079 | * the entries read from the ring buffer and the number of | |
4080 | * entries that were overwritten. | |
4081 | */ | |
4082 | static inline unsigned long | |
4083 | rb_num_of_entries(struct ring_buffer_per_cpu *cpu_buffer) | |
4084 | { | |
4085 | return local_read(&cpu_buffer->entries) - | |
4086 | (local_read(&cpu_buffer->overrun) + cpu_buffer->read); | |
4087 | } | |
4088 | ||
c64e148a VN |
4089 | /** |
4090 | * ring_buffer_oldest_event_ts - get the oldest event timestamp from the buffer | |
4091 | * @buffer: The ring buffer | |
4092 | * @cpu: The per CPU buffer to read from. | |
4093 | */ | |
13292494 | 4094 | u64 ring_buffer_oldest_event_ts(struct trace_buffer *buffer, int cpu) |
c64e148a VN |
4095 | { |
4096 | unsigned long flags; | |
4097 | struct ring_buffer_per_cpu *cpu_buffer; | |
4098 | struct buffer_page *bpage; | |
da830e58 | 4099 | u64 ret = 0; |
c64e148a VN |
4100 | |
4101 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
4102 | return 0; | |
4103 | ||
4104 | cpu_buffer = buffer->buffers[cpu]; | |
7115e3fc | 4105 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
c64e148a VN |
4106 | /* |
4107 | * if the tail is on reader_page, oldest time stamp is on the reader | |
4108 | * page | |
4109 | */ | |
4110 | if (cpu_buffer->tail_page == cpu_buffer->reader_page) | |
4111 | bpage = cpu_buffer->reader_page; | |
4112 | else | |
4113 | bpage = rb_set_head_page(cpu_buffer); | |
54f7be5b SR |
4114 | if (bpage) |
4115 | ret = bpage->page->time_stamp; | |
7115e3fc | 4116 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
c64e148a VN |
4117 | |
4118 | return ret; | |
4119 | } | |
4120 | EXPORT_SYMBOL_GPL(ring_buffer_oldest_event_ts); | |
4121 | ||
4122 | /** | |
45d99ea4 | 4123 | * ring_buffer_bytes_cpu - get the number of bytes unconsumed in a cpu buffer |
c64e148a VN |
4124 | * @buffer: The ring buffer |
4125 | * @cpu: The per CPU buffer to read from. | |
4126 | */ | |
13292494 | 4127 | unsigned long ring_buffer_bytes_cpu(struct trace_buffer *buffer, int cpu) |
c64e148a VN |
4128 | { |
4129 | struct ring_buffer_per_cpu *cpu_buffer; | |
4130 | unsigned long ret; | |
4131 | ||
4132 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
4133 | return 0; | |
4134 | ||
4135 | cpu_buffer = buffer->buffers[cpu]; | |
4136 | ret = local_read(&cpu_buffer->entries_bytes) - cpu_buffer->read_bytes; | |
4137 | ||
4138 | return ret; | |
4139 | } | |
4140 | EXPORT_SYMBOL_GPL(ring_buffer_bytes_cpu); | |
4141 | ||
7a8e76a3 SR |
4142 | /** |
4143 | * ring_buffer_entries_cpu - get the number of entries in a cpu buffer | |
4144 | * @buffer: The ring buffer | |
4145 | * @cpu: The per CPU buffer to get the entries from. | |
4146 | */ | |
13292494 | 4147 | unsigned long ring_buffer_entries_cpu(struct trace_buffer *buffer, int cpu) |
7a8e76a3 SR |
4148 | { |
4149 | struct ring_buffer_per_cpu *cpu_buffer; | |
4150 | ||
9e01c1b7 | 4151 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 4152 | return 0; |
7a8e76a3 SR |
4153 | |
4154 | cpu_buffer = buffer->buffers[cpu]; | |
554f786e | 4155 | |
f6195aa0 | 4156 | return rb_num_of_entries(cpu_buffer); |
7a8e76a3 | 4157 | } |
c4f50183 | 4158 | EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu); |
7a8e76a3 SR |
4159 | |
4160 | /** | |
884bfe89 SP |
4161 | * ring_buffer_overrun_cpu - get the number of overruns caused by the ring |
4162 | * buffer wrapping around (only if RB_FL_OVERWRITE is on). | |
7a8e76a3 SR |
4163 | * @buffer: The ring buffer |
4164 | * @cpu: The per CPU buffer to get the number of overruns from | |
4165 | */ | |
13292494 | 4166 | unsigned long ring_buffer_overrun_cpu(struct trace_buffer *buffer, int cpu) |
7a8e76a3 SR |
4167 | { |
4168 | struct ring_buffer_per_cpu *cpu_buffer; | |
8aabee57 | 4169 | unsigned long ret; |
7a8e76a3 | 4170 | |
9e01c1b7 | 4171 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 4172 | return 0; |
7a8e76a3 SR |
4173 | |
4174 | cpu_buffer = buffer->buffers[cpu]; | |
77ae365e | 4175 | ret = local_read(&cpu_buffer->overrun); |
554f786e SR |
4176 | |
4177 | return ret; | |
7a8e76a3 | 4178 | } |
c4f50183 | 4179 | EXPORT_SYMBOL_GPL(ring_buffer_overrun_cpu); |
7a8e76a3 | 4180 | |
f0d2c681 | 4181 | /** |
884bfe89 SP |
4182 | * ring_buffer_commit_overrun_cpu - get the number of overruns caused by |
4183 | * commits failing due to the buffer wrapping around while there are uncommitted | |
4184 | * events, such as during an interrupt storm. | |
f0d2c681 SR |
4185 | * @buffer: The ring buffer |
4186 | * @cpu: The per CPU buffer to get the number of overruns from | |
4187 | */ | |
4188 | unsigned long | |
13292494 | 4189 | ring_buffer_commit_overrun_cpu(struct trace_buffer *buffer, int cpu) |
f0d2c681 SR |
4190 | { |
4191 | struct ring_buffer_per_cpu *cpu_buffer; | |
4192 | unsigned long ret; | |
4193 | ||
4194 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
4195 | return 0; | |
4196 | ||
4197 | cpu_buffer = buffer->buffers[cpu]; | |
77ae365e | 4198 | ret = local_read(&cpu_buffer->commit_overrun); |
f0d2c681 SR |
4199 | |
4200 | return ret; | |
4201 | } | |
4202 | EXPORT_SYMBOL_GPL(ring_buffer_commit_overrun_cpu); | |
4203 | ||
884bfe89 SP |
4204 | /** |
4205 | * ring_buffer_dropped_events_cpu - get the number of dropped events caused by | |
4206 | * the ring buffer filling up (only if RB_FL_OVERWRITE is off). | |
4207 | * @buffer: The ring buffer | |
4208 | * @cpu: The per CPU buffer to get the number of overruns from | |
4209 | */ | |
4210 | unsigned long | |
13292494 | 4211 | ring_buffer_dropped_events_cpu(struct trace_buffer *buffer, int cpu) |
884bfe89 SP |
4212 | { |
4213 | struct ring_buffer_per_cpu *cpu_buffer; | |
4214 | unsigned long ret; | |
4215 | ||
4216 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
4217 | return 0; | |
4218 | ||
4219 | cpu_buffer = buffer->buffers[cpu]; | |
4220 | ret = local_read(&cpu_buffer->dropped_events); | |
4221 | ||
4222 | return ret; | |
4223 | } | |
4224 | EXPORT_SYMBOL_GPL(ring_buffer_dropped_events_cpu); | |
4225 | ||
ad964704 SRRH |
4226 | /** |
4227 | * ring_buffer_read_events_cpu - get the number of events successfully read | |
4228 | * @buffer: The ring buffer | |
4229 | * @cpu: The per CPU buffer to get the number of events read | |
4230 | */ | |
4231 | unsigned long | |
13292494 | 4232 | ring_buffer_read_events_cpu(struct trace_buffer *buffer, int cpu) |
ad964704 SRRH |
4233 | { |
4234 | struct ring_buffer_per_cpu *cpu_buffer; | |
4235 | ||
4236 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
4237 | return 0; | |
4238 | ||
4239 | cpu_buffer = buffer->buffers[cpu]; | |
4240 | return cpu_buffer->read; | |
4241 | } | |
4242 | EXPORT_SYMBOL_GPL(ring_buffer_read_events_cpu); | |
4243 | ||
7a8e76a3 SR |
4244 | /** |
4245 | * ring_buffer_entries - get the number of entries in a buffer | |
4246 | * @buffer: The ring buffer | |
4247 | * | |
4248 | * Returns the total number of entries in the ring buffer | |
4249 | * (all CPU entries) | |
4250 | */ | |
13292494 | 4251 | unsigned long ring_buffer_entries(struct trace_buffer *buffer) |
7a8e76a3 SR |
4252 | { |
4253 | struct ring_buffer_per_cpu *cpu_buffer; | |
4254 | unsigned long entries = 0; | |
4255 | int cpu; | |
4256 | ||
4257 | /* if you care about this being correct, lock the buffer */ | |
4258 | for_each_buffer_cpu(buffer, cpu) { | |
4259 | cpu_buffer = buffer->buffers[cpu]; | |
f6195aa0 | 4260 | entries += rb_num_of_entries(cpu_buffer); |
7a8e76a3 SR |
4261 | } |
4262 | ||
4263 | return entries; | |
4264 | } | |
c4f50183 | 4265 | EXPORT_SYMBOL_GPL(ring_buffer_entries); |
7a8e76a3 SR |
4266 | |
4267 | /** | |
67b394f7 | 4268 | * ring_buffer_overruns - get the number of overruns in buffer |
7a8e76a3 SR |
4269 | * @buffer: The ring buffer |
4270 | * | |
4271 | * Returns the total number of overruns in the ring buffer | |
4272 | * (all CPU entries) | |
4273 | */ | |
13292494 | 4274 | unsigned long ring_buffer_overruns(struct trace_buffer *buffer) |
7a8e76a3 SR |
4275 | { |
4276 | struct ring_buffer_per_cpu *cpu_buffer; | |
4277 | unsigned long overruns = 0; | |
4278 | int cpu; | |
4279 | ||
4280 | /* if you care about this being correct, lock the buffer */ | |
4281 | for_each_buffer_cpu(buffer, cpu) { | |
4282 | cpu_buffer = buffer->buffers[cpu]; | |
77ae365e | 4283 | overruns += local_read(&cpu_buffer->overrun); |
7a8e76a3 SR |
4284 | } |
4285 | ||
4286 | return overruns; | |
4287 | } | |
c4f50183 | 4288 | EXPORT_SYMBOL_GPL(ring_buffer_overruns); |
7a8e76a3 | 4289 | |
642edba5 | 4290 | static void rb_iter_reset(struct ring_buffer_iter *iter) |
7a8e76a3 SR |
4291 | { |
4292 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
4293 | ||
d769041f | 4294 | /* Iterator usage is expected to have record disabled */ |
651e22f2 SRRH |
4295 | iter->head_page = cpu_buffer->reader_page; |
4296 | iter->head = cpu_buffer->reader_page->read; | |
785888c5 | 4297 | iter->next_event = iter->head; |
651e22f2 SRRH |
4298 | |
4299 | iter->cache_reader_page = iter->head_page; | |
24607f11 | 4300 | iter->cache_read = cpu_buffer->read; |
2d093282 | 4301 | iter->cache_pages_removed = cpu_buffer->pages_removed; |
651e22f2 | 4302 | |
28e3fc56 | 4303 | if (iter->head) { |
d769041f | 4304 | iter->read_stamp = cpu_buffer->read_stamp; |
28e3fc56 SRV |
4305 | iter->page_stamp = cpu_buffer->reader_page->page->time_stamp; |
4306 | } else { | |
abc9b56d | 4307 | iter->read_stamp = iter->head_page->page->time_stamp; |
28e3fc56 SRV |
4308 | iter->page_stamp = iter->read_stamp; |
4309 | } | |
642edba5 | 4310 | } |
f83c9d0f | 4311 | |
642edba5 SR |
4312 | /** |
4313 | * ring_buffer_iter_reset - reset an iterator | |
4314 | * @iter: The iterator to reset | |
4315 | * | |
4316 | * Resets the iterator, so that it will start from the beginning | |
4317 | * again. | |
4318 | */ | |
4319 | void ring_buffer_iter_reset(struct ring_buffer_iter *iter) | |
4320 | { | |
554f786e | 4321 | struct ring_buffer_per_cpu *cpu_buffer; |
642edba5 SR |
4322 | unsigned long flags; |
4323 | ||
554f786e SR |
4324 | if (!iter) |
4325 | return; | |
4326 | ||
4327 | cpu_buffer = iter->cpu_buffer; | |
4328 | ||
5389f6fa | 4329 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
642edba5 | 4330 | rb_iter_reset(iter); |
5389f6fa | 4331 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
7a8e76a3 | 4332 | } |
c4f50183 | 4333 | EXPORT_SYMBOL_GPL(ring_buffer_iter_reset); |
7a8e76a3 SR |
4334 | |
4335 | /** | |
4336 | * ring_buffer_iter_empty - check if an iterator has no more to read | |
4337 | * @iter: The iterator to check | |
4338 | */ | |
4339 | int ring_buffer_iter_empty(struct ring_buffer_iter *iter) | |
4340 | { | |
4341 | struct ring_buffer_per_cpu *cpu_buffer; | |
78f7a45d SRV |
4342 | struct buffer_page *reader; |
4343 | struct buffer_page *head_page; | |
4344 | struct buffer_page *commit_page; | |
ead6ecfd | 4345 | struct buffer_page *curr_commit_page; |
78f7a45d | 4346 | unsigned commit; |
ead6ecfd SRV |
4347 | u64 curr_commit_ts; |
4348 | u64 commit_ts; | |
7a8e76a3 SR |
4349 | |
4350 | cpu_buffer = iter->cpu_buffer; | |
78f7a45d SRV |
4351 | reader = cpu_buffer->reader_page; |
4352 | head_page = cpu_buffer->head_page; | |
4353 | commit_page = cpu_buffer->commit_page; | |
ead6ecfd SRV |
4354 | commit_ts = commit_page->page->time_stamp; |
4355 | ||
4356 | /* | |
4357 | * When the writer goes across pages, it issues a cmpxchg which | |
4358 | * is a mb(), which will synchronize with the rmb here. | |
4359 | * (see rb_tail_page_update()) | |
4360 | */ | |
4361 | smp_rmb(); | |
78f7a45d | 4362 | commit = rb_page_commit(commit_page); |
ead6ecfd SRV |
4363 | /* We want to make sure that the commit page doesn't change */ |
4364 | smp_rmb(); | |
4365 | ||
4366 | /* Make sure commit page didn't change */ | |
4367 | curr_commit_page = READ_ONCE(cpu_buffer->commit_page); | |
4368 | curr_commit_ts = READ_ONCE(curr_commit_page->page->time_stamp); | |
4369 | ||
4370 | /* If the commit page changed, then there's more data */ | |
4371 | if (curr_commit_page != commit_page || | |
4372 | curr_commit_ts != commit_ts) | |
4373 | return 0; | |
78f7a45d | 4374 | |
ead6ecfd | 4375 | /* Still racy, as it may return a false positive, but that's OK */ |
785888c5 | 4376 | return ((iter->head_page == commit_page && iter->head >= commit) || |
78f7a45d SRV |
4377 | (iter->head_page == reader && commit_page == head_page && |
4378 | head_page->read == commit && | |
4379 | iter->head == rb_page_commit(cpu_buffer->reader_page))); | |
7a8e76a3 | 4380 | } |
c4f50183 | 4381 | EXPORT_SYMBOL_GPL(ring_buffer_iter_empty); |
7a8e76a3 SR |
4382 | |
4383 | static void | |
4384 | rb_update_read_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
4385 | struct ring_buffer_event *event) | |
4386 | { | |
4387 | u64 delta; | |
4388 | ||
334d4169 | 4389 | switch (event->type_len) { |
7a8e76a3 SR |
4390 | case RINGBUF_TYPE_PADDING: |
4391 | return; | |
4392 | ||
4393 | case RINGBUF_TYPE_TIME_EXTEND: | |
e20044f7 | 4394 | delta = rb_event_time_stamp(event); |
7a8e76a3 SR |
4395 | cpu_buffer->read_stamp += delta; |
4396 | return; | |
4397 | ||
4398 | case RINGBUF_TYPE_TIME_STAMP: | |
e20044f7 | 4399 | delta = rb_event_time_stamp(event); |
6695da58 | 4400 | delta = rb_fix_abs_ts(delta, cpu_buffer->read_stamp); |
dc4e2801 | 4401 | cpu_buffer->read_stamp = delta; |
7a8e76a3 SR |
4402 | return; |
4403 | ||
4404 | case RINGBUF_TYPE_DATA: | |
4405 | cpu_buffer->read_stamp += event->time_delta; | |
4406 | return; | |
4407 | ||
4408 | default: | |
da4d401a | 4409 | RB_WARN_ON(cpu_buffer, 1); |
7a8e76a3 | 4410 | } |
7a8e76a3 SR |
4411 | } |
4412 | ||
4413 | static void | |
4414 | rb_update_iter_read_stamp(struct ring_buffer_iter *iter, | |
4415 | struct ring_buffer_event *event) | |
4416 | { | |
4417 | u64 delta; | |
4418 | ||
334d4169 | 4419 | switch (event->type_len) { |
7a8e76a3 SR |
4420 | case RINGBUF_TYPE_PADDING: |
4421 | return; | |
4422 | ||
4423 | case RINGBUF_TYPE_TIME_EXTEND: | |
e20044f7 | 4424 | delta = rb_event_time_stamp(event); |
7a8e76a3 SR |
4425 | iter->read_stamp += delta; |
4426 | return; | |
4427 | ||
4428 | case RINGBUF_TYPE_TIME_STAMP: | |
e20044f7 | 4429 | delta = rb_event_time_stamp(event); |
6695da58 | 4430 | delta = rb_fix_abs_ts(delta, iter->read_stamp); |
dc4e2801 | 4431 | iter->read_stamp = delta; |
7a8e76a3 SR |
4432 | return; |
4433 | ||
4434 | case RINGBUF_TYPE_DATA: | |
4435 | iter->read_stamp += event->time_delta; | |
4436 | return; | |
4437 | ||
4438 | default: | |
da4d401a | 4439 | RB_WARN_ON(iter->cpu_buffer, 1); |
7a8e76a3 | 4440 | } |
7a8e76a3 SR |
4441 | } |
4442 | ||
d769041f SR |
4443 | static struct buffer_page * |
4444 | rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) | |
7a8e76a3 | 4445 | { |
d769041f | 4446 | struct buffer_page *reader = NULL; |
139f8400 | 4447 | unsigned long bsize = READ_ONCE(cpu_buffer->buffer->subbuf_size); |
66a8cb95 | 4448 | unsigned long overwrite; |
d769041f | 4449 | unsigned long flags; |
818e3dd3 | 4450 | int nr_loops = 0; |
bc92b956 | 4451 | bool ret; |
d769041f | 4452 | |
3e03fb7f | 4453 | local_irq_save(flags); |
0199c4e6 | 4454 | arch_spin_lock(&cpu_buffer->lock); |
d769041f SR |
4455 | |
4456 | again: | |
818e3dd3 SR |
4457 | /* |
4458 | * This should normally only loop twice. But because the | |
4459 | * start of the reader inserts an empty page, it causes | |
4460 | * a case where we will loop three times. There should be no | |
4461 | * reason to loop four times (that I know of). | |
4462 | */ | |
3e89c7bb | 4463 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 3)) { |
818e3dd3 SR |
4464 | reader = NULL; |
4465 | goto out; | |
4466 | } | |
4467 | ||
d769041f SR |
4468 | reader = cpu_buffer->reader_page; |
4469 | ||
4470 | /* If there's more to read, return this page */ | |
bf41a158 | 4471 | if (cpu_buffer->reader_page->read < rb_page_size(reader)) |
d769041f SR |
4472 | goto out; |
4473 | ||
4474 | /* Never should we have an index greater than the size */ | |
3e89c7bb SR |
4475 | if (RB_WARN_ON(cpu_buffer, |
4476 | cpu_buffer->reader_page->read > rb_page_size(reader))) | |
4477 | goto out; | |
d769041f SR |
4478 | |
4479 | /* check if we caught up to the tail */ | |
4480 | reader = NULL; | |
bf41a158 | 4481 | if (cpu_buffer->commit_page == cpu_buffer->reader_page) |
d769041f | 4482 | goto out; |
7a8e76a3 | 4483 | |
a5fb8331 SR |
4484 | /* Don't bother swapping if the ring buffer is empty */ |
4485 | if (rb_num_of_entries(cpu_buffer) == 0) | |
4486 | goto out; | |
4487 | ||
7a8e76a3 | 4488 | /* |
d769041f | 4489 | * Reset the reader page to size zero. |
7a8e76a3 | 4490 | */ |
77ae365e SR |
4491 | local_set(&cpu_buffer->reader_page->write, 0); |
4492 | local_set(&cpu_buffer->reader_page->entries, 0); | |
4493 | local_set(&cpu_buffer->reader_page->page->commit, 0); | |
ff0ff84a | 4494 | cpu_buffer->reader_page->real_end = 0; |
7a8e76a3 | 4495 | |
77ae365e SR |
4496 | spin: |
4497 | /* | |
4498 | * Splice the empty reader page into the list around the head. | |
4499 | */ | |
4500 | reader = rb_set_head_page(cpu_buffer); | |
54f7be5b SR |
4501 | if (!reader) |
4502 | goto out; | |
0e1ff5d7 | 4503 | cpu_buffer->reader_page->list.next = rb_list_head(reader->list.next); |
d769041f | 4504 | cpu_buffer->reader_page->list.prev = reader->list.prev; |
bf41a158 | 4505 | |
3adc54fa SR |
4506 | /* |
4507 | * cpu_buffer->pages just needs to point to the buffer, it | |
4508 | * has no specific buffer page to point to. Lets move it out | |
25985edc | 4509 | * of our way so we don't accidentally swap it. |
3adc54fa SR |
4510 | */ |
4511 | cpu_buffer->pages = reader->list.prev; | |
4512 | ||
77ae365e | 4513 | /* The reader page will be pointing to the new head */ |
6689bed3 | 4514 | rb_set_list_to_head(&cpu_buffer->reader_page->list); |
7a8e76a3 | 4515 | |
66a8cb95 SR |
4516 | /* |
4517 | * We want to make sure we read the overruns after we set up our | |
4518 | * pointers to the next object. The writer side does a | |
4519 | * cmpxchg to cross pages which acts as the mb on the writer | |
4520 | * side. Note, the reader will constantly fail the swap | |
4521 | * while the writer is updating the pointers, so this | |
4522 | * guarantees that the overwrite recorded here is the one we | |
4523 | * want to compare with the last_overrun. | |
4524 | */ | |
4525 | smp_mb(); | |
4526 | overwrite = local_read(&(cpu_buffer->overrun)); | |
4527 | ||
77ae365e SR |
4528 | /* |
4529 | * Here's the tricky part. | |
4530 | * | |
4531 | * We need to move the pointer past the header page. | |
4532 | * But we can only do that if a writer is not currently | |
4533 | * moving it. The page before the header page has the | |
4534 | * flag bit '1' set if it is pointing to the page we want. | |
4535 | * but if the writer is in the process of moving it | |
4536 | * than it will be '2' or already moved '0'. | |
4537 | */ | |
4538 | ||
4539 | ret = rb_head_page_replace(reader, cpu_buffer->reader_page); | |
7a8e76a3 SR |
4540 | |
4541 | /* | |
77ae365e | 4542 | * If we did not convert it, then we must try again. |
7a8e76a3 | 4543 | */ |
77ae365e SR |
4544 | if (!ret) |
4545 | goto spin; | |
7a8e76a3 | 4546 | |
77ae365e | 4547 | /* |
2c2b0a78 | 4548 | * Yay! We succeeded in replacing the page. |
77ae365e SR |
4549 | * |
4550 | * Now make the new head point back to the reader page. | |
4551 | */ | |
5ded3dc6 | 4552 | rb_list_head(reader->list.next)->prev = &cpu_buffer->reader_page->list; |
6689bed3 | 4553 | rb_inc_page(&cpu_buffer->head_page); |
d769041f | 4554 | |
2c2b0a78 SRV |
4555 | local_inc(&cpu_buffer->pages_read); |
4556 | ||
d769041f SR |
4557 | /* Finally update the reader page to the new head */ |
4558 | cpu_buffer->reader_page = reader; | |
b81f472a | 4559 | cpu_buffer->reader_page->read = 0; |
d769041f | 4560 | |
66a8cb95 SR |
4561 | if (overwrite != cpu_buffer->last_overrun) { |
4562 | cpu_buffer->lost_events = overwrite - cpu_buffer->last_overrun; | |
4563 | cpu_buffer->last_overrun = overwrite; | |
4564 | } | |
4565 | ||
d769041f SR |
4566 | goto again; |
4567 | ||
4568 | out: | |
b81f472a SRRH |
4569 | /* Update the read_stamp on the first event */ |
4570 | if (reader && reader->read == 0) | |
4571 | cpu_buffer->read_stamp = reader->page->time_stamp; | |
4572 | ||
0199c4e6 | 4573 | arch_spin_unlock(&cpu_buffer->lock); |
3e03fb7f | 4574 | local_irq_restore(flags); |
d769041f | 4575 | |
a0fcaaed SRG |
4576 | /* |
4577 | * The writer has preempt disable, wait for it. But not forever | |
4578 | * Although, 1 second is pretty much "forever" | |
4579 | */ | |
4580 | #define USECS_WAIT 1000000 | |
4581 | for (nr_loops = 0; nr_loops < USECS_WAIT; nr_loops++) { | |
4582 | /* If the write is past the end of page, a writer is still updating it */ | |
139f8400 | 4583 | if (likely(!reader || rb_page_write(reader) <= bsize)) |
a0fcaaed SRG |
4584 | break; |
4585 | ||
4586 | udelay(1); | |
4587 | ||
4588 | /* Get the latest version of the reader write value */ | |
4589 | smp_rmb(); | |
4590 | } | |
4591 | ||
4592 | /* The writer is not moving forward? Something is wrong */ | |
4593 | if (RB_WARN_ON(cpu_buffer, nr_loops == USECS_WAIT)) | |
4594 | reader = NULL; | |
4595 | ||
4596 | /* | |
4597 | * Make sure we see any padding after the write update | |
6455b616 ZY |
4598 | * (see rb_reset_tail()). |
4599 | * | |
4600 | * In addition, a writer may be writing on the reader page | |
4601 | * if the page has not been fully filled, so the read barrier | |
4602 | * is also needed to make sure we see the content of what is | |
4603 | * committed by the writer (see rb_set_commit_to_write()). | |
a0fcaaed SRG |
4604 | */ |
4605 | smp_rmb(); | |
4606 | ||
4607 | ||
d769041f SR |
4608 | return reader; |
4609 | } | |
4610 | ||
4611 | static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer) | |
4612 | { | |
4613 | struct ring_buffer_event *event; | |
4614 | struct buffer_page *reader; | |
4615 | unsigned length; | |
4616 | ||
4617 | reader = rb_get_reader_page(cpu_buffer); | |
7a8e76a3 | 4618 | |
d769041f | 4619 | /* This function should not be called when buffer is empty */ |
3e89c7bb SR |
4620 | if (RB_WARN_ON(cpu_buffer, !reader)) |
4621 | return; | |
7a8e76a3 | 4622 | |
d769041f SR |
4623 | event = rb_reader_event(cpu_buffer); |
4624 | ||
a1863c21 | 4625 | if (event->type_len <= RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
e4906eff | 4626 | cpu_buffer->read++; |
d769041f SR |
4627 | |
4628 | rb_update_read_stamp(cpu_buffer, event); | |
4629 | ||
4630 | length = rb_event_length(event); | |
6f807acd | 4631 | cpu_buffer->reader_page->read += length; |
45d99ea4 | 4632 | cpu_buffer->read_bytes += length; |
7a8e76a3 SR |
4633 | } |
4634 | ||
4635 | static void rb_advance_iter(struct ring_buffer_iter *iter) | |
4636 | { | |
7a8e76a3 | 4637 | struct ring_buffer_per_cpu *cpu_buffer; |
7a8e76a3 SR |
4638 | |
4639 | cpu_buffer = iter->cpu_buffer; | |
7a8e76a3 | 4640 | |
785888c5 SRV |
4641 | /* If head == next_event then we need to jump to the next event */ |
4642 | if (iter->head == iter->next_event) { | |
4643 | /* If the event gets overwritten again, there's nothing to do */ | |
4644 | if (rb_iter_head_event(iter) == NULL) | |
4645 | return; | |
4646 | } | |
4647 | ||
4648 | iter->head = iter->next_event; | |
4649 | ||
7a8e76a3 SR |
4650 | /* |
4651 | * Check if we are at the end of the buffer. | |
4652 | */ | |
785888c5 | 4653 | if (iter->next_event >= rb_page_size(iter->head_page)) { |
ea05b57c SR |
4654 | /* discarded commits can make the page empty */ |
4655 | if (iter->head_page == cpu_buffer->commit_page) | |
3e89c7bb | 4656 | return; |
d769041f | 4657 | rb_inc_iter(iter); |
7a8e76a3 SR |
4658 | return; |
4659 | } | |
4660 | ||
785888c5 | 4661 | rb_update_iter_read_stamp(iter, iter->event); |
7a8e76a3 SR |
4662 | } |
4663 | ||
66a8cb95 SR |
4664 | static int rb_lost_events(struct ring_buffer_per_cpu *cpu_buffer) |
4665 | { | |
4666 | return cpu_buffer->lost_events; | |
4667 | } | |
4668 | ||
f83c9d0f | 4669 | static struct ring_buffer_event * |
66a8cb95 SR |
4670 | rb_buffer_peek(struct ring_buffer_per_cpu *cpu_buffer, u64 *ts, |
4671 | unsigned long *lost_events) | |
7a8e76a3 | 4672 | { |
7a8e76a3 | 4673 | struct ring_buffer_event *event; |
d769041f | 4674 | struct buffer_page *reader; |
818e3dd3 | 4675 | int nr_loops = 0; |
7a8e76a3 | 4676 | |
dc4e2801 TZ |
4677 | if (ts) |
4678 | *ts = 0; | |
7a8e76a3 | 4679 | again: |
818e3dd3 | 4680 | /* |
69d1b839 SR |
4681 | * We repeat when a time extend is encountered. |
4682 | * Since the time extend is always attached to a data event, | |
4683 | * we should never loop more than once. | |
4684 | * (We never hit the following condition more than twice). | |
818e3dd3 | 4685 | */ |
69d1b839 | 4686 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 2)) |
818e3dd3 | 4687 | return NULL; |
818e3dd3 | 4688 | |
d769041f SR |
4689 | reader = rb_get_reader_page(cpu_buffer); |
4690 | if (!reader) | |
7a8e76a3 SR |
4691 | return NULL; |
4692 | ||
d769041f | 4693 | event = rb_reader_event(cpu_buffer); |
7a8e76a3 | 4694 | |
334d4169 | 4695 | switch (event->type_len) { |
7a8e76a3 | 4696 | case RINGBUF_TYPE_PADDING: |
2d622719 TZ |
4697 | if (rb_null_event(event)) |
4698 | RB_WARN_ON(cpu_buffer, 1); | |
4699 | /* | |
4700 | * Because the writer could be discarding every | |
4701 | * event it creates (which would probably be bad) | |
4702 | * if we were to go back to "again" then we may never | |
4703 | * catch up, and will trigger the warn on, or lock | |
4704 | * the box. Return the padding, and we will release | |
4705 | * the current locks, and try again. | |
4706 | */ | |
2d622719 | 4707 | return event; |
7a8e76a3 SR |
4708 | |
4709 | case RINGBUF_TYPE_TIME_EXTEND: | |
4710 | /* Internal data, OK to advance */ | |
d769041f | 4711 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
4712 | goto again; |
4713 | ||
4714 | case RINGBUF_TYPE_TIME_STAMP: | |
dc4e2801 | 4715 | if (ts) { |
e20044f7 | 4716 | *ts = rb_event_time_stamp(event); |
6695da58 | 4717 | *ts = rb_fix_abs_ts(*ts, reader->page->time_stamp); |
dc4e2801 TZ |
4718 | ring_buffer_normalize_time_stamp(cpu_buffer->buffer, |
4719 | cpu_buffer->cpu, ts); | |
4720 | } | |
4721 | /* Internal data, OK to advance */ | |
d769041f | 4722 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
4723 | goto again; |
4724 | ||
4725 | case RINGBUF_TYPE_DATA: | |
dc4e2801 | 4726 | if (ts && !(*ts)) { |
7a8e76a3 | 4727 | *ts = cpu_buffer->read_stamp + event->time_delta; |
d8eeb2d3 | 4728 | ring_buffer_normalize_time_stamp(cpu_buffer->buffer, |
37886f6a | 4729 | cpu_buffer->cpu, ts); |
7a8e76a3 | 4730 | } |
66a8cb95 SR |
4731 | if (lost_events) |
4732 | *lost_events = rb_lost_events(cpu_buffer); | |
7a8e76a3 SR |
4733 | return event; |
4734 | ||
4735 | default: | |
da4d401a | 4736 | RB_WARN_ON(cpu_buffer, 1); |
7a8e76a3 SR |
4737 | } |
4738 | ||
4739 | return NULL; | |
4740 | } | |
c4f50183 | 4741 | EXPORT_SYMBOL_GPL(ring_buffer_peek); |
7a8e76a3 | 4742 | |
f83c9d0f SR |
4743 | static struct ring_buffer_event * |
4744 | rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) | |
7a8e76a3 | 4745 | { |
13292494 | 4746 | struct trace_buffer *buffer; |
7a8e76a3 SR |
4747 | struct ring_buffer_per_cpu *cpu_buffer; |
4748 | struct ring_buffer_event *event; | |
818e3dd3 | 4749 | int nr_loops = 0; |
7a8e76a3 | 4750 | |
dc4e2801 TZ |
4751 | if (ts) |
4752 | *ts = 0; | |
4753 | ||
7a8e76a3 SR |
4754 | cpu_buffer = iter->cpu_buffer; |
4755 | buffer = cpu_buffer->buffer; | |
4756 | ||
492a74f4 | 4757 | /* |
2d093282 ZY |
4758 | * Check if someone performed a consuming read to the buffer |
4759 | * or removed some pages from the buffer. In these cases, | |
4760 | * iterator was invalidated and we need to reset it. | |
492a74f4 SR |
4761 | */ |
4762 | if (unlikely(iter->cache_read != cpu_buffer->read || | |
2d093282 ZY |
4763 | iter->cache_reader_page != cpu_buffer->reader_page || |
4764 | iter->cache_pages_removed != cpu_buffer->pages_removed)) | |
492a74f4 SR |
4765 | rb_iter_reset(iter); |
4766 | ||
7a8e76a3 | 4767 | again: |
3c05d748 SR |
4768 | if (ring_buffer_iter_empty(iter)) |
4769 | return NULL; | |
4770 | ||
818e3dd3 | 4771 | /* |
3d2353de SRV |
4772 | * As the writer can mess with what the iterator is trying |
4773 | * to read, just give up if we fail to get an event after | |
4774 | * three tries. The iterator is not as reliable when reading | |
4775 | * the ring buffer with an active write as the consumer is. | |
4776 | * Do not warn if the three failures is reached. | |
818e3dd3 | 4777 | */ |
3d2353de | 4778 | if (++nr_loops > 3) |
818e3dd3 | 4779 | return NULL; |
818e3dd3 | 4780 | |
7a8e76a3 SR |
4781 | if (rb_per_cpu_empty(cpu_buffer)) |
4782 | return NULL; | |
4783 | ||
10e83fd0 | 4784 | if (iter->head >= rb_page_size(iter->head_page)) { |
3c05d748 SR |
4785 | rb_inc_iter(iter); |
4786 | goto again; | |
4787 | } | |
4788 | ||
7a8e76a3 | 4789 | event = rb_iter_head_event(iter); |
3d2353de | 4790 | if (!event) |
785888c5 | 4791 | goto again; |
7a8e76a3 | 4792 | |
334d4169 | 4793 | switch (event->type_len) { |
7a8e76a3 | 4794 | case RINGBUF_TYPE_PADDING: |
2d622719 TZ |
4795 | if (rb_null_event(event)) { |
4796 | rb_inc_iter(iter); | |
4797 | goto again; | |
4798 | } | |
4799 | rb_advance_iter(iter); | |
4800 | return event; | |
7a8e76a3 SR |
4801 | |
4802 | case RINGBUF_TYPE_TIME_EXTEND: | |
4803 | /* Internal data, OK to advance */ | |
4804 | rb_advance_iter(iter); | |
4805 | goto again; | |
4806 | ||
4807 | case RINGBUF_TYPE_TIME_STAMP: | |
dc4e2801 | 4808 | if (ts) { |
e20044f7 | 4809 | *ts = rb_event_time_stamp(event); |
6695da58 | 4810 | *ts = rb_fix_abs_ts(*ts, iter->head_page->page->time_stamp); |
dc4e2801 TZ |
4811 | ring_buffer_normalize_time_stamp(cpu_buffer->buffer, |
4812 | cpu_buffer->cpu, ts); | |
4813 | } | |
4814 | /* Internal data, OK to advance */ | |
7a8e76a3 SR |
4815 | rb_advance_iter(iter); |
4816 | goto again; | |
4817 | ||
4818 | case RINGBUF_TYPE_DATA: | |
dc4e2801 | 4819 | if (ts && !(*ts)) { |
7a8e76a3 | 4820 | *ts = iter->read_stamp + event->time_delta; |
37886f6a SR |
4821 | ring_buffer_normalize_time_stamp(buffer, |
4822 | cpu_buffer->cpu, ts); | |
7a8e76a3 SR |
4823 | } |
4824 | return event; | |
4825 | ||
4826 | default: | |
da4d401a | 4827 | RB_WARN_ON(cpu_buffer, 1); |
7a8e76a3 SR |
4828 | } |
4829 | ||
4830 | return NULL; | |
4831 | } | |
c4f50183 | 4832 | EXPORT_SYMBOL_GPL(ring_buffer_iter_peek); |
7a8e76a3 | 4833 | |
289a5a25 | 4834 | static inline bool rb_reader_lock(struct ring_buffer_per_cpu *cpu_buffer) |
8d707e8e | 4835 | { |
289a5a25 SRRH |
4836 | if (likely(!in_nmi())) { |
4837 | raw_spin_lock(&cpu_buffer->reader_lock); | |
4838 | return true; | |
4839 | } | |
4840 | ||
8d707e8e SR |
4841 | /* |
4842 | * If an NMI die dumps out the content of the ring buffer | |
289a5a25 SRRH |
4843 | * trylock must be used to prevent a deadlock if the NMI |
4844 | * preempted a task that holds the ring buffer locks. If | |
4845 | * we get the lock then all is fine, if not, then continue | |
4846 | * to do the read, but this can corrupt the ring buffer, | |
4847 | * so it must be permanently disabled from future writes. | |
4848 | * Reading from NMI is a oneshot deal. | |
8d707e8e | 4849 | */ |
289a5a25 SRRH |
4850 | if (raw_spin_trylock(&cpu_buffer->reader_lock)) |
4851 | return true; | |
8d707e8e | 4852 | |
289a5a25 SRRH |
4853 | /* Continue without locking, but disable the ring buffer */ |
4854 | atomic_inc(&cpu_buffer->record_disabled); | |
4855 | return false; | |
4856 | } | |
4857 | ||
4858 | static inline void | |
4859 | rb_reader_unlock(struct ring_buffer_per_cpu *cpu_buffer, bool locked) | |
4860 | { | |
4861 | if (likely(locked)) | |
4862 | raw_spin_unlock(&cpu_buffer->reader_lock); | |
8d707e8e SR |
4863 | } |
4864 | ||
f83c9d0f SR |
4865 | /** |
4866 | * ring_buffer_peek - peek at the next event to be read | |
4867 | * @buffer: The ring buffer to read | |
4868 | * @cpu: The cpu to peak at | |
4869 | * @ts: The timestamp counter of this event. | |
66a8cb95 | 4870 | * @lost_events: a variable to store if events were lost (may be NULL) |
f83c9d0f SR |
4871 | * |
4872 | * This will return the event that will be read next, but does | |
4873 | * not consume the data. | |
4874 | */ | |
4875 | struct ring_buffer_event * | |
13292494 | 4876 | ring_buffer_peek(struct trace_buffer *buffer, int cpu, u64 *ts, |
66a8cb95 | 4877 | unsigned long *lost_events) |
f83c9d0f SR |
4878 | { |
4879 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
8aabee57 | 4880 | struct ring_buffer_event *event; |
f83c9d0f | 4881 | unsigned long flags; |
289a5a25 | 4882 | bool dolock; |
f83c9d0f | 4883 | |
554f786e | 4884 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 4885 | return NULL; |
554f786e | 4886 | |
2d622719 | 4887 | again: |
8d707e8e | 4888 | local_irq_save(flags); |
289a5a25 | 4889 | dolock = rb_reader_lock(cpu_buffer); |
66a8cb95 | 4890 | event = rb_buffer_peek(cpu_buffer, ts, lost_events); |
469535a5 RR |
4891 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
4892 | rb_advance_reader(cpu_buffer); | |
289a5a25 | 4893 | rb_reader_unlock(cpu_buffer, dolock); |
8d707e8e | 4894 | local_irq_restore(flags); |
f83c9d0f | 4895 | |
1b959e18 | 4896 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
2d622719 | 4897 | goto again; |
2d622719 | 4898 | |
f83c9d0f SR |
4899 | return event; |
4900 | } | |
4901 | ||
c9b7a4a7 SRV |
4902 | /** ring_buffer_iter_dropped - report if there are dropped events |
4903 | * @iter: The ring buffer iterator | |
4904 | * | |
4905 | * Returns true if there was dropped events since the last peek. | |
4906 | */ | |
4907 | bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter) | |
4908 | { | |
4909 | bool ret = iter->missed_events != 0; | |
4910 | ||
4911 | iter->missed_events = 0; | |
4912 | return ret; | |
4913 | } | |
4914 | EXPORT_SYMBOL_GPL(ring_buffer_iter_dropped); | |
4915 | ||
f83c9d0f SR |
4916 | /** |
4917 | * ring_buffer_iter_peek - peek at the next event to be read | |
4918 | * @iter: The ring buffer iterator | |
4919 | * @ts: The timestamp counter of this event. | |
4920 | * | |
4921 | * This will return the event that will be read next, but does | |
4922 | * not increment the iterator. | |
4923 | */ | |
4924 | struct ring_buffer_event * | |
4925 | ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) | |
4926 | { | |
4927 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
4928 | struct ring_buffer_event *event; | |
4929 | unsigned long flags; | |
4930 | ||
2d622719 | 4931 | again: |
5389f6fa | 4932 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
f83c9d0f | 4933 | event = rb_iter_peek(iter, ts); |
5389f6fa | 4934 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
f83c9d0f | 4935 | |
1b959e18 | 4936 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
2d622719 | 4937 | goto again; |
2d622719 | 4938 | |
f83c9d0f SR |
4939 | return event; |
4940 | } | |
4941 | ||
7a8e76a3 SR |
4942 | /** |
4943 | * ring_buffer_consume - return an event and consume it | |
4944 | * @buffer: The ring buffer to get the next event from | |
66a8cb95 SR |
4945 | * @cpu: the cpu to read the buffer from |
4946 | * @ts: a variable to store the timestamp (may be NULL) | |
4947 | * @lost_events: a variable to store if events were lost (may be NULL) | |
7a8e76a3 SR |
4948 | * |
4949 | * Returns the next event in the ring buffer, and that event is consumed. | |
4950 | * Meaning, that sequential reads will keep returning a different event, | |
4951 | * and eventually empty the ring buffer if the producer is slower. | |
4952 | */ | |
4953 | struct ring_buffer_event * | |
13292494 | 4954 | ring_buffer_consume(struct trace_buffer *buffer, int cpu, u64 *ts, |
66a8cb95 | 4955 | unsigned long *lost_events) |
7a8e76a3 | 4956 | { |
554f786e SR |
4957 | struct ring_buffer_per_cpu *cpu_buffer; |
4958 | struct ring_buffer_event *event = NULL; | |
f83c9d0f | 4959 | unsigned long flags; |
289a5a25 | 4960 | bool dolock; |
7a8e76a3 | 4961 | |
2d622719 | 4962 | again: |
554f786e SR |
4963 | /* might be called in atomic */ |
4964 | preempt_disable(); | |
4965 | ||
9e01c1b7 | 4966 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
554f786e | 4967 | goto out; |
7a8e76a3 | 4968 | |
554f786e | 4969 | cpu_buffer = buffer->buffers[cpu]; |
8d707e8e | 4970 | local_irq_save(flags); |
289a5a25 | 4971 | dolock = rb_reader_lock(cpu_buffer); |
f83c9d0f | 4972 | |
66a8cb95 SR |
4973 | event = rb_buffer_peek(cpu_buffer, ts, lost_events); |
4974 | if (event) { | |
4975 | cpu_buffer->lost_events = 0; | |
469535a5 | 4976 | rb_advance_reader(cpu_buffer); |
66a8cb95 | 4977 | } |
7a8e76a3 | 4978 | |
289a5a25 | 4979 | rb_reader_unlock(cpu_buffer, dolock); |
8d707e8e | 4980 | local_irq_restore(flags); |
f83c9d0f | 4981 | |
554f786e SR |
4982 | out: |
4983 | preempt_enable(); | |
4984 | ||
1b959e18 | 4985 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
2d622719 | 4986 | goto again; |
2d622719 | 4987 | |
7a8e76a3 SR |
4988 | return event; |
4989 | } | |
c4f50183 | 4990 | EXPORT_SYMBOL_GPL(ring_buffer_consume); |
7a8e76a3 SR |
4991 | |
4992 | /** | |
72c9ddfd | 4993 | * ring_buffer_read_prepare - Prepare for a non consuming read of the buffer |
7a8e76a3 SR |
4994 | * @buffer: The ring buffer to read from |
4995 | * @cpu: The cpu buffer to iterate over | |
31b265b3 | 4996 | * @flags: gfp flags to use for memory allocation |
7a8e76a3 | 4997 | * |
72c9ddfd DM |
4998 | * This performs the initial preparations necessary to iterate |
4999 | * through the buffer. Memory is allocated, buffer recording | |
5000 | * is disabled, and the iterator pointer is returned to the caller. | |
7a8e76a3 | 5001 | * |
6167c205 | 5002 | * Disabling buffer recording prevents the reading from being |
72c9ddfd DM |
5003 | * corrupted. This is not a consuming read, so a producer is not |
5004 | * expected. | |
5005 | * | |
5006 | * After a sequence of ring_buffer_read_prepare calls, the user is | |
d611851b | 5007 | * expected to make at least one call to ring_buffer_read_prepare_sync. |
72c9ddfd DM |
5008 | * Afterwards, ring_buffer_read_start is invoked to get things going |
5009 | * for real. | |
5010 | * | |
d611851b | 5011 | * This overall must be paired with ring_buffer_read_finish. |
7a8e76a3 SR |
5012 | */ |
5013 | struct ring_buffer_iter * | |
13292494 | 5014 | ring_buffer_read_prepare(struct trace_buffer *buffer, int cpu, gfp_t flags) |
7a8e76a3 SR |
5015 | { |
5016 | struct ring_buffer_per_cpu *cpu_buffer; | |
8aabee57 | 5017 | struct ring_buffer_iter *iter; |
7a8e76a3 | 5018 | |
9e01c1b7 | 5019 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 5020 | return NULL; |
7a8e76a3 | 5021 | |
785888c5 | 5022 | iter = kzalloc(sizeof(*iter), flags); |
7a8e76a3 | 5023 | if (!iter) |
8aabee57 | 5024 | return NULL; |
7a8e76a3 | 5025 | |
b0495258 | 5026 | /* Holds the entire event: data and meta data */ |
139f8400 TSV |
5027 | iter->event_size = buffer->subbuf_size; |
5028 | iter->event = kmalloc(iter->event_size, flags); | |
785888c5 SRV |
5029 | if (!iter->event) { |
5030 | kfree(iter); | |
5031 | return NULL; | |
5032 | } | |
5033 | ||
7a8e76a3 SR |
5034 | cpu_buffer = buffer->buffers[cpu]; |
5035 | ||
5036 | iter->cpu_buffer = cpu_buffer; | |
5037 | ||
07b8b10e | 5038 | atomic_inc(&cpu_buffer->resize_disabled); |
72c9ddfd DM |
5039 | |
5040 | return iter; | |
5041 | } | |
5042 | EXPORT_SYMBOL_GPL(ring_buffer_read_prepare); | |
5043 | ||
5044 | /** | |
5045 | * ring_buffer_read_prepare_sync - Synchronize a set of prepare calls | |
5046 | * | |
5047 | * All previously invoked ring_buffer_read_prepare calls to prepare | |
5048 | * iterators will be synchronized. Afterwards, read_buffer_read_start | |
5049 | * calls on those iterators are allowed. | |
5050 | */ | |
5051 | void | |
5052 | ring_buffer_read_prepare_sync(void) | |
5053 | { | |
74401729 | 5054 | synchronize_rcu(); |
72c9ddfd DM |
5055 | } |
5056 | EXPORT_SYMBOL_GPL(ring_buffer_read_prepare_sync); | |
5057 | ||
5058 | /** | |
5059 | * ring_buffer_read_start - start a non consuming read of the buffer | |
5060 | * @iter: The iterator returned by ring_buffer_read_prepare | |
5061 | * | |
5062 | * This finalizes the startup of an iteration through the buffer. | |
5063 | * The iterator comes from a call to ring_buffer_read_prepare and | |
5064 | * an intervening ring_buffer_read_prepare_sync must have been | |
5065 | * performed. | |
5066 | * | |
d611851b | 5067 | * Must be paired with ring_buffer_read_finish. |
72c9ddfd DM |
5068 | */ |
5069 | void | |
5070 | ring_buffer_read_start(struct ring_buffer_iter *iter) | |
5071 | { | |
5072 | struct ring_buffer_per_cpu *cpu_buffer; | |
5073 | unsigned long flags; | |
5074 | ||
5075 | if (!iter) | |
5076 | return; | |
5077 | ||
5078 | cpu_buffer = iter->cpu_buffer; | |
7a8e76a3 | 5079 | |
5389f6fa | 5080 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
0199c4e6 | 5081 | arch_spin_lock(&cpu_buffer->lock); |
642edba5 | 5082 | rb_iter_reset(iter); |
0199c4e6 | 5083 | arch_spin_unlock(&cpu_buffer->lock); |
5389f6fa | 5084 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
7a8e76a3 | 5085 | } |
c4f50183 | 5086 | EXPORT_SYMBOL_GPL(ring_buffer_read_start); |
7a8e76a3 SR |
5087 | |
5088 | /** | |
d611851b | 5089 | * ring_buffer_read_finish - finish reading the iterator of the buffer |
7a8e76a3 SR |
5090 | * @iter: The iterator retrieved by ring_buffer_start |
5091 | * | |
5092 | * This re-enables the recording to the buffer, and frees the | |
5093 | * iterator. | |
5094 | */ | |
5095 | void | |
5096 | ring_buffer_read_finish(struct ring_buffer_iter *iter) | |
5097 | { | |
5098 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
9366c1ba | 5099 | unsigned long flags; |
7a8e76a3 | 5100 | |
659f451f SR |
5101 | /* |
5102 | * Ring buffer is disabled from recording, here's a good place | |
9366c1ba SR |
5103 | * to check the integrity of the ring buffer. |
5104 | * Must prevent readers from trying to read, as the check | |
5105 | * clears the HEAD page and readers require it. | |
659f451f | 5106 | */ |
9366c1ba | 5107 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
659f451f | 5108 | rb_check_pages(cpu_buffer); |
9366c1ba | 5109 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
659f451f | 5110 | |
07b8b10e | 5111 | atomic_dec(&cpu_buffer->resize_disabled); |
785888c5 | 5112 | kfree(iter->event); |
7a8e76a3 SR |
5113 | kfree(iter); |
5114 | } | |
c4f50183 | 5115 | EXPORT_SYMBOL_GPL(ring_buffer_read_finish); |
7a8e76a3 SR |
5116 | |
5117 | /** | |
bc1a72af | 5118 | * ring_buffer_iter_advance - advance the iterator to the next location |
7a8e76a3 | 5119 | * @iter: The ring buffer iterator |
7a8e76a3 | 5120 | * |
bc1a72af SRV |
5121 | * Move the location of the iterator such that the next read will |
5122 | * be the next location of the iterator. | |
7a8e76a3 | 5123 | */ |
bc1a72af | 5124 | void ring_buffer_iter_advance(struct ring_buffer_iter *iter) |
7a8e76a3 | 5125 | { |
f83c9d0f SR |
5126 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
5127 | unsigned long flags; | |
7a8e76a3 | 5128 | |
5389f6fa | 5129 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
7e9391cf | 5130 | |
7a8e76a3 SR |
5131 | rb_advance_iter(iter); |
5132 | ||
bc1a72af | 5133 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
7a8e76a3 | 5134 | } |
bc1a72af | 5135 | EXPORT_SYMBOL_GPL(ring_buffer_iter_advance); |
7a8e76a3 SR |
5136 | |
5137 | /** | |
5138 | * ring_buffer_size - return the size of the ring buffer (in bytes) | |
5139 | * @buffer: The ring buffer. | |
59e7cffe | 5140 | * @cpu: The CPU to get ring buffer size from. |
7a8e76a3 | 5141 | */ |
13292494 | 5142 | unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu) |
7a8e76a3 | 5143 | { |
438ced17 VN |
5144 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
5145 | return 0; | |
5146 | ||
139f8400 | 5147 | return buffer->subbuf_size * buffer->buffers[cpu]->nr_pages; |
7a8e76a3 | 5148 | } |
c4f50183 | 5149 | EXPORT_SYMBOL_GPL(ring_buffer_size); |
7a8e76a3 | 5150 | |
8ec90be7 SRG |
5151 | /** |
5152 | * ring_buffer_max_event_size - return the max data size of an event | |
5153 | * @buffer: The ring buffer. | |
5154 | * | |
5155 | * Returns the maximum size an event can be. | |
5156 | */ | |
5157 | unsigned long ring_buffer_max_event_size(struct trace_buffer *buffer) | |
5158 | { | |
5159 | /* If abs timestamp is requested, events have a timestamp too */ | |
5160 | if (ring_buffer_time_stamp_abs(buffer)) | |
139f8400 TSV |
5161 | return buffer->max_data_size - RB_LEN_TIME_EXTEND; |
5162 | return buffer->max_data_size; | |
8ec90be7 SRG |
5163 | } |
5164 | EXPORT_SYMBOL_GPL(ring_buffer_max_event_size); | |
5165 | ||
7e42907f ZY |
5166 | static void rb_clear_buffer_page(struct buffer_page *page) |
5167 | { | |
5168 | local_set(&page->write, 0); | |
5169 | local_set(&page->entries, 0); | |
5170 | rb_init_page(page->page); | |
5171 | page->read = 0; | |
5172 | } | |
5173 | ||
7a8e76a3 SR |
5174 | static void |
5175 | rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) | |
5176 | { | |
7e42907f ZY |
5177 | struct buffer_page *page; |
5178 | ||
77ae365e SR |
5179 | rb_head_page_deactivate(cpu_buffer); |
5180 | ||
7a8e76a3 | 5181 | cpu_buffer->head_page |
3adc54fa | 5182 | = list_entry(cpu_buffer->pages, struct buffer_page, list); |
7e42907f ZY |
5183 | rb_clear_buffer_page(cpu_buffer->head_page); |
5184 | list_for_each_entry(page, cpu_buffer->pages, list) { | |
5185 | rb_clear_buffer_page(page); | |
5186 | } | |
bf41a158 SR |
5187 | |
5188 | cpu_buffer->tail_page = cpu_buffer->head_page; | |
5189 | cpu_buffer->commit_page = cpu_buffer->head_page; | |
5190 | ||
5191 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); | |
5040b4b7 | 5192 | INIT_LIST_HEAD(&cpu_buffer->new_pages); |
7e42907f | 5193 | rb_clear_buffer_page(cpu_buffer->reader_page); |
7a8e76a3 | 5194 | |
c64e148a | 5195 | local_set(&cpu_buffer->entries_bytes, 0); |
77ae365e | 5196 | local_set(&cpu_buffer->overrun, 0); |
884bfe89 SP |
5197 | local_set(&cpu_buffer->commit_overrun, 0); |
5198 | local_set(&cpu_buffer->dropped_events, 0); | |
e4906eff | 5199 | local_set(&cpu_buffer->entries, 0); |
fa743953 SR |
5200 | local_set(&cpu_buffer->committing, 0); |
5201 | local_set(&cpu_buffer->commits, 0); | |
2c2b0a78 | 5202 | local_set(&cpu_buffer->pages_touched, 0); |
31029a8b | 5203 | local_set(&cpu_buffer->pages_lost, 0); |
2c2b0a78 | 5204 | local_set(&cpu_buffer->pages_read, 0); |
03329f99 | 5205 | cpu_buffer->last_pages_touch = 0; |
2c2b0a78 | 5206 | cpu_buffer->shortest_full = 0; |
77ae365e | 5207 | cpu_buffer->read = 0; |
c64e148a | 5208 | cpu_buffer->read_bytes = 0; |
69507c06 | 5209 | |
10464b4a SRV |
5210 | rb_time_set(&cpu_buffer->write_stamp, 0); |
5211 | rb_time_set(&cpu_buffer->before_stamp, 0); | |
77ae365e | 5212 | |
8672e494 SRV |
5213 | memset(cpu_buffer->event_stamp, 0, sizeof(cpu_buffer->event_stamp)); |
5214 | ||
66a8cb95 SR |
5215 | cpu_buffer->lost_events = 0; |
5216 | cpu_buffer->last_overrun = 0; | |
5217 | ||
77ae365e | 5218 | rb_head_page_activate(cpu_buffer); |
2d093282 | 5219 | cpu_buffer->pages_removed = 0; |
7a8e76a3 SR |
5220 | } |
5221 | ||
b23d7a5f NP |
5222 | /* Must have disabled the cpu buffer then done a synchronize_rcu */ |
5223 | static void reset_disabled_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) | |
5224 | { | |
5225 | unsigned long flags; | |
5226 | ||
5227 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
5228 | ||
5229 | if (RB_WARN_ON(cpu_buffer, local_read(&cpu_buffer->committing))) | |
5230 | goto out; | |
5231 | ||
5232 | arch_spin_lock(&cpu_buffer->lock); | |
5233 | ||
5234 | rb_reset_cpu(cpu_buffer); | |
5235 | ||
5236 | arch_spin_unlock(&cpu_buffer->lock); | |
5237 | ||
5238 | out: | |
5239 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
5240 | } | |
5241 | ||
7a8e76a3 SR |
5242 | /** |
5243 | * ring_buffer_reset_cpu - reset a ring buffer per CPU buffer | |
5244 | * @buffer: The ring buffer to reset a per cpu buffer of | |
5245 | * @cpu: The CPU buffer to be reset | |
5246 | */ | |
13292494 | 5247 | void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu) |
7a8e76a3 SR |
5248 | { |
5249 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 | 5250 | |
9e01c1b7 | 5251 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 5252 | return; |
7a8e76a3 | 5253 | |
bbeb9746 GK |
5254 | /* prevent another thread from changing buffer sizes */ |
5255 | mutex_lock(&buffer->mutex); | |
5256 | ||
07b8b10e | 5257 | atomic_inc(&cpu_buffer->resize_disabled); |
41ede23e SR |
5258 | atomic_inc(&cpu_buffer->record_disabled); |
5259 | ||
83f40318 | 5260 | /* Make sure all commits have finished */ |
74401729 | 5261 | synchronize_rcu(); |
83f40318 | 5262 | |
b23d7a5f | 5263 | reset_disabled_cpu_buffer(cpu_buffer); |
f83c9d0f | 5264 | |
b23d7a5f NP |
5265 | atomic_dec(&cpu_buffer->record_disabled); |
5266 | atomic_dec(&cpu_buffer->resize_disabled); | |
bbeb9746 GK |
5267 | |
5268 | mutex_unlock(&buffer->mutex); | |
b23d7a5f NP |
5269 | } |
5270 | EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); | |
41b6a95d | 5271 | |
7c339fb4 TW |
5272 | /* Flag to ensure proper resetting of atomic variables */ |
5273 | #define RESET_BIT (1 << 30) | |
5274 | ||
b23d7a5f | 5275 | /** |
b7085b6f | 5276 | * ring_buffer_reset_online_cpus - reset a ring buffer per CPU buffer |
b23d7a5f | 5277 | * @buffer: The ring buffer to reset a per cpu buffer of |
b23d7a5f NP |
5278 | */ |
5279 | void ring_buffer_reset_online_cpus(struct trace_buffer *buffer) | |
5280 | { | |
5281 | struct ring_buffer_per_cpu *cpu_buffer; | |
5282 | int cpu; | |
7a8e76a3 | 5283 | |
bbeb9746 GK |
5284 | /* prevent another thread from changing buffer sizes */ |
5285 | mutex_lock(&buffer->mutex); | |
5286 | ||
b23d7a5f NP |
5287 | for_each_online_buffer_cpu(buffer, cpu) { |
5288 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 | 5289 | |
7c339fb4 | 5290 | atomic_add(RESET_BIT, &cpu_buffer->resize_disabled); |
b23d7a5f NP |
5291 | atomic_inc(&cpu_buffer->record_disabled); |
5292 | } | |
f83c9d0f | 5293 | |
b23d7a5f NP |
5294 | /* Make sure all commits have finished */ |
5295 | synchronize_rcu(); | |
41ede23e | 5296 | |
7c339fb4 | 5297 | for_each_buffer_cpu(buffer, cpu) { |
b23d7a5f NP |
5298 | cpu_buffer = buffer->buffers[cpu]; |
5299 | ||
7c339fb4 TW |
5300 | /* |
5301 | * If a CPU came online during the synchronize_rcu(), then | |
5302 | * ignore it. | |
5303 | */ | |
5304 | if (!(atomic_read(&cpu_buffer->resize_disabled) & RESET_BIT)) | |
5305 | continue; | |
5306 | ||
b23d7a5f NP |
5307 | reset_disabled_cpu_buffer(cpu_buffer); |
5308 | ||
5309 | atomic_dec(&cpu_buffer->record_disabled); | |
7c339fb4 | 5310 | atomic_sub(RESET_BIT, &cpu_buffer->resize_disabled); |
b23d7a5f | 5311 | } |
bbeb9746 GK |
5312 | |
5313 | mutex_unlock(&buffer->mutex); | |
7a8e76a3 SR |
5314 | } |
5315 | ||
5316 | /** | |
5317 | * ring_buffer_reset - reset a ring buffer | |
5318 | * @buffer: The ring buffer to reset all cpu buffers | |
5319 | */ | |
13292494 | 5320 | void ring_buffer_reset(struct trace_buffer *buffer) |
7a8e76a3 | 5321 | { |
b23d7a5f | 5322 | struct ring_buffer_per_cpu *cpu_buffer; |
7a8e76a3 SR |
5323 | int cpu; |
5324 | ||
51d15794 SRV |
5325 | /* prevent another thread from changing buffer sizes */ |
5326 | mutex_lock(&buffer->mutex); | |
5327 | ||
b23d7a5f NP |
5328 | for_each_buffer_cpu(buffer, cpu) { |
5329 | cpu_buffer = buffer->buffers[cpu]; | |
5330 | ||
5331 | atomic_inc(&cpu_buffer->resize_disabled); | |
5332 | atomic_inc(&cpu_buffer->record_disabled); | |
5333 | } | |
5334 | ||
5335 | /* Make sure all commits have finished */ | |
5336 | synchronize_rcu(); | |
5337 | ||
5338 | for_each_buffer_cpu(buffer, cpu) { | |
5339 | cpu_buffer = buffer->buffers[cpu]; | |
5340 | ||
5341 | reset_disabled_cpu_buffer(cpu_buffer); | |
5342 | ||
5343 | atomic_dec(&cpu_buffer->record_disabled); | |
5344 | atomic_dec(&cpu_buffer->resize_disabled); | |
5345 | } | |
51d15794 SRV |
5346 | |
5347 | mutex_unlock(&buffer->mutex); | |
7a8e76a3 | 5348 | } |
c4f50183 | 5349 | EXPORT_SYMBOL_GPL(ring_buffer_reset); |
7a8e76a3 SR |
5350 | |
5351 | /** | |
b7085b6f | 5352 | * ring_buffer_empty - is the ring buffer empty? |
7a8e76a3 SR |
5353 | * @buffer: The ring buffer to test |
5354 | */ | |
13292494 | 5355 | bool ring_buffer_empty(struct trace_buffer *buffer) |
7a8e76a3 SR |
5356 | { |
5357 | struct ring_buffer_per_cpu *cpu_buffer; | |
d4788207 | 5358 | unsigned long flags; |
289a5a25 | 5359 | bool dolock; |
bc92b956 | 5360 | bool ret; |
7a8e76a3 SR |
5361 | int cpu; |
5362 | ||
5363 | /* yes this is racy, but if you don't like the race, lock the buffer */ | |
5364 | for_each_buffer_cpu(buffer, cpu) { | |
5365 | cpu_buffer = buffer->buffers[cpu]; | |
8d707e8e | 5366 | local_irq_save(flags); |
289a5a25 | 5367 | dolock = rb_reader_lock(cpu_buffer); |
d4788207 | 5368 | ret = rb_per_cpu_empty(cpu_buffer); |
289a5a25 | 5369 | rb_reader_unlock(cpu_buffer, dolock); |
8d707e8e SR |
5370 | local_irq_restore(flags); |
5371 | ||
d4788207 | 5372 | if (!ret) |
3d4e204d | 5373 | return false; |
7a8e76a3 | 5374 | } |
554f786e | 5375 | |
3d4e204d | 5376 | return true; |
7a8e76a3 | 5377 | } |
c4f50183 | 5378 | EXPORT_SYMBOL_GPL(ring_buffer_empty); |
7a8e76a3 SR |
5379 | |
5380 | /** | |
5381 | * ring_buffer_empty_cpu - is a cpu buffer of a ring buffer empty? | |
5382 | * @buffer: The ring buffer | |
5383 | * @cpu: The CPU buffer to test | |
5384 | */ | |
13292494 | 5385 | bool ring_buffer_empty_cpu(struct trace_buffer *buffer, int cpu) |
7a8e76a3 SR |
5386 | { |
5387 | struct ring_buffer_per_cpu *cpu_buffer; | |
d4788207 | 5388 | unsigned long flags; |
289a5a25 | 5389 | bool dolock; |
bc92b956 | 5390 | bool ret; |
7a8e76a3 | 5391 | |
9e01c1b7 | 5392 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
3d4e204d | 5393 | return true; |
7a8e76a3 SR |
5394 | |
5395 | cpu_buffer = buffer->buffers[cpu]; | |
8d707e8e | 5396 | local_irq_save(flags); |
289a5a25 | 5397 | dolock = rb_reader_lock(cpu_buffer); |
554f786e | 5398 | ret = rb_per_cpu_empty(cpu_buffer); |
289a5a25 | 5399 | rb_reader_unlock(cpu_buffer, dolock); |
8d707e8e | 5400 | local_irq_restore(flags); |
554f786e SR |
5401 | |
5402 | return ret; | |
7a8e76a3 | 5403 | } |
c4f50183 | 5404 | EXPORT_SYMBOL_GPL(ring_buffer_empty_cpu); |
7a8e76a3 | 5405 | |
85bac32c | 5406 | #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP |
7a8e76a3 SR |
5407 | /** |
5408 | * ring_buffer_swap_cpu - swap a CPU buffer between two ring buffers | |
5409 | * @buffer_a: One buffer to swap with | |
5410 | * @buffer_b: The other buffer to swap with | |
59e7cffe | 5411 | * @cpu: the CPU of the buffers to swap |
7a8e76a3 SR |
5412 | * |
5413 | * This function is useful for tracers that want to take a "snapshot" | |
5414 | * of a CPU buffer and has another back up buffer lying around. | |
5415 | * it is expected that the tracer handles the cpu buffer not being | |
5416 | * used at the moment. | |
5417 | */ | |
13292494 SRV |
5418 | int ring_buffer_swap_cpu(struct trace_buffer *buffer_a, |
5419 | struct trace_buffer *buffer_b, int cpu) | |
7a8e76a3 SR |
5420 | { |
5421 | struct ring_buffer_per_cpu *cpu_buffer_a; | |
5422 | struct ring_buffer_per_cpu *cpu_buffer_b; | |
554f786e SR |
5423 | int ret = -EINVAL; |
5424 | ||
9e01c1b7 RR |
5425 | if (!cpumask_test_cpu(cpu, buffer_a->cpumask) || |
5426 | !cpumask_test_cpu(cpu, buffer_b->cpumask)) | |
554f786e | 5427 | goto out; |
7a8e76a3 | 5428 | |
438ced17 VN |
5429 | cpu_buffer_a = buffer_a->buffers[cpu]; |
5430 | cpu_buffer_b = buffer_b->buffers[cpu]; | |
5431 | ||
7a8e76a3 | 5432 | /* At least make sure the two buffers are somewhat the same */ |
438ced17 | 5433 | if (cpu_buffer_a->nr_pages != cpu_buffer_b->nr_pages) |
554f786e SR |
5434 | goto out; |
5435 | ||
b81e03a2 SRG |
5436 | if (buffer_a->subbuf_order != buffer_b->subbuf_order) |
5437 | goto out; | |
5438 | ||
554f786e | 5439 | ret = -EAGAIN; |
7a8e76a3 | 5440 | |
97b17efe | 5441 | if (atomic_read(&buffer_a->record_disabled)) |
554f786e | 5442 | goto out; |
97b17efe SR |
5443 | |
5444 | if (atomic_read(&buffer_b->record_disabled)) | |
554f786e | 5445 | goto out; |
97b17efe | 5446 | |
97b17efe | 5447 | if (atomic_read(&cpu_buffer_a->record_disabled)) |
554f786e | 5448 | goto out; |
97b17efe SR |
5449 | |
5450 | if (atomic_read(&cpu_buffer_b->record_disabled)) | |
554f786e | 5451 | goto out; |
97b17efe | 5452 | |
7a8e76a3 | 5453 | /* |
74401729 | 5454 | * We can't do a synchronize_rcu here because this |
7a8e76a3 SR |
5455 | * function can be called in atomic context. |
5456 | * Normally this will be called from the same CPU as cpu. | |
5457 | * If not it's up to the caller to protect this. | |
5458 | */ | |
5459 | atomic_inc(&cpu_buffer_a->record_disabled); | |
5460 | atomic_inc(&cpu_buffer_b->record_disabled); | |
5461 | ||
98277991 SR |
5462 | ret = -EBUSY; |
5463 | if (local_read(&cpu_buffer_a->committing)) | |
5464 | goto out_dec; | |
5465 | if (local_read(&cpu_buffer_b->committing)) | |
5466 | goto out_dec; | |
5467 | ||
8a96c028 CL |
5468 | /* |
5469 | * When resize is in progress, we cannot swap it because | |
5470 | * it will mess the state of the cpu buffer. | |
5471 | */ | |
5472 | if (atomic_read(&buffer_a->resizing)) | |
5473 | goto out_dec; | |
5474 | if (atomic_read(&buffer_b->resizing)) | |
5475 | goto out_dec; | |
5476 | ||
7a8e76a3 SR |
5477 | buffer_a->buffers[cpu] = cpu_buffer_b; |
5478 | buffer_b->buffers[cpu] = cpu_buffer_a; | |
5479 | ||
5480 | cpu_buffer_b->buffer = buffer_a; | |
5481 | cpu_buffer_a->buffer = buffer_b; | |
5482 | ||
98277991 SR |
5483 | ret = 0; |
5484 | ||
5485 | out_dec: | |
7a8e76a3 SR |
5486 | atomic_dec(&cpu_buffer_a->record_disabled); |
5487 | atomic_dec(&cpu_buffer_b->record_disabled); | |
554f786e | 5488 | out: |
554f786e | 5489 | return ret; |
7a8e76a3 | 5490 | } |
c4f50183 | 5491 | EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu); |
85bac32c | 5492 | #endif /* CONFIG_RING_BUFFER_ALLOW_SWAP */ |
7a8e76a3 | 5493 | |
8789a9e7 SR |
5494 | /** |
5495 | * ring_buffer_alloc_read_page - allocate a page to read from buffer | |
5496 | * @buffer: the buffer to allocate for. | |
d611851b | 5497 | * @cpu: the cpu buffer to allocate. |
8789a9e7 SR |
5498 | * |
5499 | * This function is used in conjunction with ring_buffer_read_page. | |
5500 | * When reading a full page from the ring buffer, these functions | |
5501 | * can be used to speed up the process. The calling function should | |
5502 | * allocate a few pages first with this function. Then when it | |
5503 | * needs to get pages from the ring buffer, it passes the result | |
5504 | * of this function into ring_buffer_read_page, which will swap | |
5505 | * the page that was allocated, with the read page of the buffer. | |
5506 | * | |
5507 | * Returns: | |
a7e52ad7 | 5508 | * The page allocated, or ERR_PTR |
8789a9e7 | 5509 | */ |
bce761d7 TSV |
5510 | struct buffer_data_read_page * |
5511 | ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu) | |
8789a9e7 | 5512 | { |
a7e52ad7 | 5513 | struct ring_buffer_per_cpu *cpu_buffer; |
bce761d7 | 5514 | struct buffer_data_read_page *bpage = NULL; |
73a757e6 | 5515 | unsigned long flags; |
7ea59064 | 5516 | struct page *page; |
8789a9e7 | 5517 | |
a7e52ad7 SRV |
5518 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
5519 | return ERR_PTR(-ENODEV); | |
5520 | ||
bce761d7 TSV |
5521 | bpage = kzalloc(sizeof(*bpage), GFP_KERNEL); |
5522 | if (!bpage) | |
5523 | return ERR_PTR(-ENOMEM); | |
5524 | ||
5525 | bpage->order = buffer->subbuf_order; | |
a7e52ad7 | 5526 | cpu_buffer = buffer->buffers[cpu]; |
73a757e6 SRV |
5527 | local_irq_save(flags); |
5528 | arch_spin_lock(&cpu_buffer->lock); | |
5529 | ||
5530 | if (cpu_buffer->free_page) { | |
bce761d7 | 5531 | bpage->data = cpu_buffer->free_page; |
73a757e6 SRV |
5532 | cpu_buffer->free_page = NULL; |
5533 | } | |
5534 | ||
5535 | arch_spin_unlock(&cpu_buffer->lock); | |
5536 | local_irq_restore(flags); | |
5537 | ||
bce761d7 | 5538 | if (bpage->data) |
73a757e6 SRV |
5539 | goto out; |
5540 | ||
f9b94daa TSV |
5541 | page = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL | __GFP_NORETRY, |
5542 | cpu_buffer->buffer->subbuf_order); | |
bce761d7 TSV |
5543 | if (!page) { |
5544 | kfree(bpage); | |
a7e52ad7 | 5545 | return ERR_PTR(-ENOMEM); |
bce761d7 | 5546 | } |
8789a9e7 | 5547 | |
bce761d7 | 5548 | bpage->data = page_address(page); |
8789a9e7 | 5549 | |
73a757e6 | 5550 | out: |
bce761d7 | 5551 | rb_init_page(bpage->data); |
ef7a4a16 | 5552 | |
044fa782 | 5553 | return bpage; |
8789a9e7 | 5554 | } |
d6ce96da | 5555 | EXPORT_SYMBOL_GPL(ring_buffer_alloc_read_page); |
8789a9e7 SR |
5556 | |
5557 | /** | |
5558 | * ring_buffer_free_read_page - free an allocated read page | |
5559 | * @buffer: the buffer the page was allocate for | |
73a757e6 | 5560 | * @cpu: the cpu buffer the page came from |
bce761d7 | 5561 | * @data_page: the page to free |
8789a9e7 SR |
5562 | * |
5563 | * Free a page allocated from ring_buffer_alloc_read_page. | |
5564 | */ | |
bce761d7 TSV |
5565 | void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu, |
5566 | struct buffer_data_read_page *data_page) | |
8789a9e7 | 5567 | { |
3e4272b9 | 5568 | struct ring_buffer_per_cpu *cpu_buffer; |
bce761d7 | 5569 | struct buffer_data_page *bpage = data_page->data; |
ae415fa4 | 5570 | struct page *page = virt_to_page(bpage); |
73a757e6 SRV |
5571 | unsigned long flags; |
5572 | ||
3e4272b9 JJB |
5573 | if (!buffer || !buffer->buffers || !buffer->buffers[cpu]) |
5574 | return; | |
5575 | ||
5576 | cpu_buffer = buffer->buffers[cpu]; | |
5577 | ||
bce761d7 TSV |
5578 | /* |
5579 | * If the page is still in use someplace else, or order of the page | |
5580 | * is different from the subbuffer order of the buffer - | |
5581 | * we can't reuse it | |
5582 | */ | |
5583 | if (page_ref_count(page) > 1 || data_page->order != buffer->subbuf_order) | |
ae415fa4 SRV |
5584 | goto out; |
5585 | ||
73a757e6 SRV |
5586 | local_irq_save(flags); |
5587 | arch_spin_lock(&cpu_buffer->lock); | |
5588 | ||
5589 | if (!cpu_buffer->free_page) { | |
5590 | cpu_buffer->free_page = bpage; | |
5591 | bpage = NULL; | |
5592 | } | |
5593 | ||
5594 | arch_spin_unlock(&cpu_buffer->lock); | |
5595 | local_irq_restore(flags); | |
5596 | ||
ae415fa4 | 5597 | out: |
bce761d7 TSV |
5598 | free_pages((unsigned long)bpage, data_page->order); |
5599 | kfree(data_page); | |
8789a9e7 | 5600 | } |
d6ce96da | 5601 | EXPORT_SYMBOL_GPL(ring_buffer_free_read_page); |
8789a9e7 SR |
5602 | |
5603 | /** | |
5604 | * ring_buffer_read_page - extract a page from the ring buffer | |
5605 | * @buffer: buffer to extract from | |
5606 | * @data_page: the page to use allocated from ring_buffer_alloc_read_page | |
ef7a4a16 | 5607 | * @len: amount to extract |
8789a9e7 SR |
5608 | * @cpu: the cpu of the buffer to extract |
5609 | * @full: should the extraction only happen when the page is full. | |
5610 | * | |
5611 | * This function will pull out a page from the ring buffer and consume it. | |
5612 | * @data_page must be the address of the variable that was returned | |
5613 | * from ring_buffer_alloc_read_page. This is because the page might be used | |
5614 | * to swap with a page in the ring buffer. | |
5615 | * | |
5616 | * for example: | |
d611851b | 5617 | * rpage = ring_buffer_alloc_read_page(buffer, cpu); |
a7e52ad7 SRV |
5618 | * if (IS_ERR(rpage)) |
5619 | * return PTR_ERR(rpage); | |
bce761d7 | 5620 | * ret = ring_buffer_read_page(buffer, rpage, len, cpu, 0); |
667d2412 | 5621 | * if (ret >= 0) |
bce761d7 TSV |
5622 | * process_page(ring_buffer_read_page_data(rpage), ret); |
5623 | * ring_buffer_free_read_page(buffer, cpu, rpage); | |
8789a9e7 SR |
5624 | * |
5625 | * When @full is set, the function will not return true unless | |
5626 | * the writer is off the reader page. | |
5627 | * | |
5628 | * Note: it is up to the calling functions to handle sleeps and wakeups. | |
5629 | * The ring buffer can be used anywhere in the kernel and can not | |
5630 | * blindly call wake_up. The layer that uses the ring buffer must be | |
5631 | * responsible for that. | |
5632 | * | |
5633 | * Returns: | |
667d2412 LJ |
5634 | * >=0 if data has been transferred, returns the offset of consumed data. |
5635 | * <0 if no data has been transferred. | |
8789a9e7 | 5636 | */ |
13292494 | 5637 | int ring_buffer_read_page(struct trace_buffer *buffer, |
bce761d7 TSV |
5638 | struct buffer_data_read_page *data_page, |
5639 | size_t len, int cpu, int full) | |
8789a9e7 SR |
5640 | { |
5641 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
5642 | struct ring_buffer_event *event; | |
044fa782 | 5643 | struct buffer_data_page *bpage; |
ef7a4a16 | 5644 | struct buffer_page *reader; |
ff0ff84a | 5645 | unsigned long missed_events; |
8789a9e7 | 5646 | unsigned long flags; |
ef7a4a16 | 5647 | unsigned int commit; |
667d2412 | 5648 | unsigned int read; |
4f3640f8 | 5649 | u64 save_timestamp; |
667d2412 | 5650 | int ret = -1; |
8789a9e7 | 5651 | |
554f786e SR |
5652 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
5653 | goto out; | |
5654 | ||
474d32b6 SR |
5655 | /* |
5656 | * If len is not big enough to hold the page header, then | |
5657 | * we can not copy anything. | |
5658 | */ | |
5659 | if (len <= BUF_PAGE_HDR_SIZE) | |
554f786e | 5660 | goto out; |
474d32b6 SR |
5661 | |
5662 | len -= BUF_PAGE_HDR_SIZE; | |
5663 | ||
bce761d7 TSV |
5664 | if (!data_page || !data_page->data) |
5665 | goto out; | |
5666 | if (data_page->order != buffer->subbuf_order) | |
554f786e | 5667 | goto out; |
8789a9e7 | 5668 | |
bce761d7 | 5669 | bpage = data_page->data; |
044fa782 | 5670 | if (!bpage) |
554f786e | 5671 | goto out; |
8789a9e7 | 5672 | |
5389f6fa | 5673 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
8789a9e7 | 5674 | |
ef7a4a16 SR |
5675 | reader = rb_get_reader_page(cpu_buffer); |
5676 | if (!reader) | |
554f786e | 5677 | goto out_unlock; |
8789a9e7 | 5678 | |
ef7a4a16 SR |
5679 | event = rb_reader_event(cpu_buffer); |
5680 | ||
5681 | read = reader->read; | |
5682 | commit = rb_page_commit(reader); | |
667d2412 | 5683 | |
66a8cb95 | 5684 | /* Check if any events were dropped */ |
ff0ff84a | 5685 | missed_events = cpu_buffer->lost_events; |
66a8cb95 | 5686 | |
8789a9e7 | 5687 | /* |
474d32b6 SR |
5688 | * If this page has been partially read or |
5689 | * if len is not big enough to read the rest of the page or | |
5690 | * a writer is still on the page, then | |
5691 | * we must copy the data from the page to the buffer. | |
5692 | * Otherwise, we can simply swap the page with the one passed in. | |
8789a9e7 | 5693 | */ |
474d32b6 | 5694 | if (read || (len < (commit - read)) || |
ef7a4a16 | 5695 | cpu_buffer->reader_page == cpu_buffer->commit_page) { |
667d2412 | 5696 | struct buffer_data_page *rpage = cpu_buffer->reader_page->page; |
474d32b6 SR |
5697 | unsigned int rpos = read; |
5698 | unsigned int pos = 0; | |
ef7a4a16 | 5699 | unsigned int size; |
8789a9e7 | 5700 | |
fa8f4a89 SRG |
5701 | /* |
5702 | * If a full page is expected, this can still be returned | |
5703 | * if there's been a previous partial read and the | |
5704 | * rest of the page can be read and the commit page is off | |
5705 | * the reader page. | |
5706 | */ | |
5707 | if (full && | |
5708 | (!read || (len < (commit - read)) || | |
5709 | cpu_buffer->reader_page == cpu_buffer->commit_page)) | |
554f786e | 5710 | goto out_unlock; |
8789a9e7 | 5711 | |
ef7a4a16 SR |
5712 | if (len > (commit - read)) |
5713 | len = (commit - read); | |
5714 | ||
69d1b839 SR |
5715 | /* Always keep the time extend and data together */ |
5716 | size = rb_event_ts_length(event); | |
ef7a4a16 SR |
5717 | |
5718 | if (len < size) | |
554f786e | 5719 | goto out_unlock; |
ef7a4a16 | 5720 | |
4f3640f8 SR |
5721 | /* save the current timestamp, since the user will need it */ |
5722 | save_timestamp = cpu_buffer->read_stamp; | |
5723 | ||
ef7a4a16 SR |
5724 | /* Need to copy one event at a time */ |
5725 | do { | |
e1e35927 DS |
5726 | /* We need the size of one event, because |
5727 | * rb_advance_reader only advances by one event, | |
5728 | * whereas rb_event_ts_length may include the size of | |
5729 | * one or two events. | |
5730 | * We have already ensured there's enough space if this | |
5731 | * is a time extend. */ | |
5732 | size = rb_event_length(event); | |
474d32b6 | 5733 | memcpy(bpage->data + pos, rpage->data + rpos, size); |
ef7a4a16 SR |
5734 | |
5735 | len -= size; | |
5736 | ||
5737 | rb_advance_reader(cpu_buffer); | |
474d32b6 SR |
5738 | rpos = reader->read; |
5739 | pos += size; | |
ef7a4a16 | 5740 | |
18fab912 HY |
5741 | if (rpos >= commit) |
5742 | break; | |
5743 | ||
ef7a4a16 | 5744 | event = rb_reader_event(cpu_buffer); |
69d1b839 SR |
5745 | /* Always keep the time extend and data together */ |
5746 | size = rb_event_ts_length(event); | |
e1e35927 | 5747 | } while (len >= size); |
667d2412 LJ |
5748 | |
5749 | /* update bpage */ | |
ef7a4a16 | 5750 | local_set(&bpage->commit, pos); |
4f3640f8 | 5751 | bpage->time_stamp = save_timestamp; |
ef7a4a16 | 5752 | |
474d32b6 SR |
5753 | /* we copied everything to the beginning */ |
5754 | read = 0; | |
8789a9e7 | 5755 | } else { |
afbab76a | 5756 | /* update the entry counter */ |
77ae365e | 5757 | cpu_buffer->read += rb_page_entries(reader); |
45d99ea4 | 5758 | cpu_buffer->read_bytes += rb_page_commit(reader); |
afbab76a | 5759 | |
8789a9e7 | 5760 | /* swap the pages */ |
044fa782 | 5761 | rb_init_page(bpage); |
ef7a4a16 | 5762 | bpage = reader->page; |
bce761d7 | 5763 | reader->page = data_page->data; |
ef7a4a16 | 5764 | local_set(&reader->write, 0); |
778c55d4 | 5765 | local_set(&reader->entries, 0); |
ef7a4a16 | 5766 | reader->read = 0; |
bce761d7 | 5767 | data_page->data = bpage; |
ff0ff84a SR |
5768 | |
5769 | /* | |
5770 | * Use the real_end for the data size, | |
5771 | * This gives us a chance to store the lost events | |
5772 | * on the page. | |
5773 | */ | |
5774 | if (reader->real_end) | |
5775 | local_set(&bpage->commit, reader->real_end); | |
8789a9e7 | 5776 | } |
667d2412 | 5777 | ret = read; |
8789a9e7 | 5778 | |
66a8cb95 | 5779 | cpu_buffer->lost_events = 0; |
2711ca23 SR |
5780 | |
5781 | commit = local_read(&bpage->commit); | |
66a8cb95 SR |
5782 | /* |
5783 | * Set a flag in the commit field if we lost events | |
5784 | */ | |
ff0ff84a | 5785 | if (missed_events) { |
ff0ff84a SR |
5786 | /* If there is room at the end of the page to save the |
5787 | * missed events, then record it there. | |
5788 | */ | |
139f8400 | 5789 | if (buffer->subbuf_size - commit >= sizeof(missed_events)) { |
ff0ff84a SR |
5790 | memcpy(&bpage->data[commit], &missed_events, |
5791 | sizeof(missed_events)); | |
5792 | local_add(RB_MISSED_STORED, &bpage->commit); | |
2711ca23 | 5793 | commit += sizeof(missed_events); |
ff0ff84a | 5794 | } |
66a8cb95 | 5795 | local_add(RB_MISSED_EVENTS, &bpage->commit); |
ff0ff84a | 5796 | } |
66a8cb95 | 5797 | |
2711ca23 SR |
5798 | /* |
5799 | * This page may be off to user land. Zero it out here. | |
5800 | */ | |
139f8400 TSV |
5801 | if (commit < buffer->subbuf_size) |
5802 | memset(&bpage->data[commit], 0, buffer->subbuf_size - commit); | |
2711ca23 | 5803 | |
554f786e | 5804 | out_unlock: |
5389f6fa | 5805 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
8789a9e7 | 5806 | |
554f786e | 5807 | out: |
8789a9e7 SR |
5808 | return ret; |
5809 | } | |
d6ce96da | 5810 | EXPORT_SYMBOL_GPL(ring_buffer_read_page); |
8789a9e7 | 5811 | |
bce761d7 TSV |
5812 | /** |
5813 | * ring_buffer_read_page_data - get pointer to the data in the page. | |
5814 | * @page: the page to get the data from | |
5815 | * | |
5816 | * Returns pointer to the actual data in this page. | |
5817 | */ | |
5818 | void *ring_buffer_read_page_data(struct buffer_data_read_page *page) | |
5819 | { | |
5820 | return page->data; | |
5821 | } | |
5822 | EXPORT_SYMBOL_GPL(ring_buffer_read_page_data); | |
5823 | ||
2808e31e TSV |
5824 | /** |
5825 | * ring_buffer_subbuf_size_get - get size of the sub buffer. | |
5826 | * @buffer: the buffer to get the sub buffer size from | |
5827 | * | |
5828 | * Returns size of the sub buffer, in bytes. | |
5829 | */ | |
5830 | int ring_buffer_subbuf_size_get(struct trace_buffer *buffer) | |
5831 | { | |
5832 | return buffer->subbuf_size + BUF_PAGE_HDR_SIZE; | |
5833 | } | |
5834 | EXPORT_SYMBOL_GPL(ring_buffer_subbuf_size_get); | |
5835 | ||
5836 | /** | |
5837 | * ring_buffer_subbuf_order_get - get order of system sub pages in one buffer page. | |
5838 | * @buffer: The ring_buffer to get the system sub page order from | |
5839 | * | |
5840 | * By default, one ring buffer sub page equals to one system page. This parameter | |
5841 | * is configurable, per ring buffer. The size of the ring buffer sub page can be | |
5842 | * extended, but must be an order of system page size. | |
5843 | * | |
5844 | * Returns the order of buffer sub page size, in system pages: | |
5845 | * 0 means the sub buffer size is 1 system page and so forth. | |
5846 | * In case of an error < 0 is returned. | |
5847 | */ | |
5848 | int ring_buffer_subbuf_order_get(struct trace_buffer *buffer) | |
5849 | { | |
5850 | if (!buffer) | |
5851 | return -EINVAL; | |
5852 | ||
5853 | return buffer->subbuf_order; | |
5854 | } | |
5855 | EXPORT_SYMBOL_GPL(ring_buffer_subbuf_order_get); | |
5856 | ||
5857 | /** | |
5858 | * ring_buffer_subbuf_order_set - set the size of ring buffer sub page. | |
5859 | * @buffer: The ring_buffer to set the new page size. | |
5860 | * @order: Order of the system pages in one sub buffer page | |
5861 | * | |
5862 | * By default, one ring buffer pages equals to one system page. This API can be | |
5863 | * used to set new size of the ring buffer page. The size must be order of | |
5864 | * system page size, that's why the input parameter @order is the order of | |
5865 | * system pages that are allocated for one ring buffer page: | |
5866 | * 0 - 1 system page | |
5867 | * 1 - 2 system pages | |
5868 | * 3 - 4 system pages | |
5869 | * ... | |
5870 | * | |
5871 | * Returns 0 on success or < 0 in case of an error. | |
5872 | */ | |
5873 | int ring_buffer_subbuf_order_set(struct trace_buffer *buffer, int order) | |
5874 | { | |
8e7b58c2 SRG |
5875 | struct ring_buffer_per_cpu *cpu_buffer; |
5876 | struct buffer_page *bpage, *tmp; | |
f9b94daa TSV |
5877 | int old_order, old_size; |
5878 | int nr_pages; | |
2808e31e | 5879 | int psize; |
f9b94daa TSV |
5880 | int err; |
5881 | int cpu; | |
2808e31e TSV |
5882 | |
5883 | if (!buffer || order < 0) | |
5884 | return -EINVAL; | |
5885 | ||
5886 | if (buffer->subbuf_order == order) | |
5887 | return 0; | |
5888 | ||
5889 | psize = (1 << order) * PAGE_SIZE; | |
5890 | if (psize <= BUF_PAGE_HDR_SIZE) | |
5891 | return -EINVAL; | |
5892 | ||
e78fb4ea SRG |
5893 | /* Size of a subbuf cannot be greater than the write counter */ |
5894 | if (psize > RB_WRITE_MASK + 1) | |
5895 | return -EINVAL; | |
5896 | ||
f9b94daa TSV |
5897 | old_order = buffer->subbuf_order; |
5898 | old_size = buffer->subbuf_size; | |
5899 | ||
5900 | /* prevent another thread from changing buffer sizes */ | |
5901 | mutex_lock(&buffer->mutex); | |
5902 | atomic_inc(&buffer->record_disabled); | |
5903 | ||
5904 | /* Make sure all commits have finished */ | |
5905 | synchronize_rcu(); | |
5906 | ||
2808e31e TSV |
5907 | buffer->subbuf_order = order; |
5908 | buffer->subbuf_size = psize - BUF_PAGE_HDR_SIZE; | |
5909 | ||
f9b94daa TSV |
5910 | /* Make sure all new buffers are allocated, before deleting the old ones */ |
5911 | for_each_buffer_cpu(buffer, cpu) { | |
8e7b58c2 | 5912 | |
f9b94daa TSV |
5913 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
5914 | continue; | |
5915 | ||
8e7b58c2 SRG |
5916 | cpu_buffer = buffer->buffers[cpu]; |
5917 | ||
353cc219 SRG |
5918 | /* Update the number of pages to match the new size */ |
5919 | nr_pages = old_size * buffer->buffers[cpu]->nr_pages; | |
5920 | nr_pages = DIV_ROUND_UP(nr_pages, buffer->subbuf_size); | |
5921 | ||
8e7b58c2 SRG |
5922 | /* we need a minimum of two pages */ |
5923 | if (nr_pages < 2) | |
5924 | nr_pages = 2; | |
5925 | ||
5926 | cpu_buffer->nr_pages_to_update = nr_pages; | |
5927 | ||
5928 | /* Include the reader page */ | |
5929 | nr_pages++; | |
5930 | ||
5931 | /* Allocate the new size buffer */ | |
5932 | INIT_LIST_HEAD(&cpu_buffer->new_pages); | |
5933 | if (__rb_allocate_pages(cpu_buffer, nr_pages, | |
5934 | &cpu_buffer->new_pages)) { | |
5935 | /* not enough memory for new pages */ | |
f9b94daa TSV |
5936 | err = -ENOMEM; |
5937 | goto error; | |
5938 | } | |
5939 | } | |
5940 | ||
5941 | for_each_buffer_cpu(buffer, cpu) { | |
8e7b58c2 | 5942 | |
f9b94daa TSV |
5943 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
5944 | continue; | |
5945 | ||
8e7b58c2 SRG |
5946 | cpu_buffer = buffer->buffers[cpu]; |
5947 | ||
5948 | /* Clear the head bit to make the link list normal to read */ | |
5949 | rb_head_page_deactivate(cpu_buffer); | |
5950 | ||
5951 | /* Now walk the list and free all the old sub buffers */ | |
5952 | list_for_each_entry_safe(bpage, tmp, cpu_buffer->pages, list) { | |
5953 | list_del_init(&bpage->list); | |
5954 | free_buffer_page(bpage); | |
5955 | } | |
5956 | /* The above loop stopped an the last page needing to be freed */ | |
5957 | bpage = list_entry(cpu_buffer->pages, struct buffer_page, list); | |
5958 | free_buffer_page(bpage); | |
5959 | ||
5960 | /* Free the current reader page */ | |
5961 | free_buffer_page(cpu_buffer->reader_page); | |
5962 | ||
5963 | /* One page was allocated for the reader page */ | |
5964 | cpu_buffer->reader_page = list_entry(cpu_buffer->new_pages.next, | |
5965 | struct buffer_page, list); | |
5966 | list_del_init(&cpu_buffer->reader_page->list); | |
5967 | ||
5968 | /* The cpu_buffer pages are a link list with no head */ | |
5969 | cpu_buffer->pages = cpu_buffer->new_pages.next; | |
5970 | cpu_buffer->new_pages.next->prev = cpu_buffer->new_pages.prev; | |
5971 | cpu_buffer->new_pages.prev->next = cpu_buffer->new_pages.next; | |
5972 | ||
5973 | /* Clear the new_pages list */ | |
5974 | INIT_LIST_HEAD(&cpu_buffer->new_pages); | |
5975 | ||
5976 | cpu_buffer->head_page | |
5977 | = list_entry(cpu_buffer->pages, struct buffer_page, list); | |
5978 | cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; | |
5979 | ||
5980 | cpu_buffer->nr_pages = cpu_buffer->nr_pages_to_update; | |
5981 | cpu_buffer->nr_pages_to_update = 0; | |
5982 | ||
5983 | free_pages((unsigned long)cpu_buffer->free_page, old_order); | |
5984 | cpu_buffer->free_page = NULL; | |
5985 | ||
5986 | rb_head_page_activate(cpu_buffer); | |
5987 | ||
5988 | rb_check_pages(cpu_buffer); | |
f9b94daa TSV |
5989 | } |
5990 | ||
5991 | atomic_dec(&buffer->record_disabled); | |
5992 | mutex_unlock(&buffer->mutex); | |
5993 | ||
2808e31e | 5994 | return 0; |
f9b94daa TSV |
5995 | |
5996 | error: | |
5997 | buffer->subbuf_order = old_order; | |
5998 | buffer->subbuf_size = old_size; | |
5999 | ||
6000 | atomic_dec(&buffer->record_disabled); | |
6001 | mutex_unlock(&buffer->mutex); | |
6002 | ||
6003 | for_each_buffer_cpu(buffer, cpu) { | |
8e7b58c2 SRG |
6004 | cpu_buffer = buffer->buffers[cpu]; |
6005 | ||
6006 | if (!cpu_buffer->nr_pages_to_update) | |
f9b94daa | 6007 | continue; |
8e7b58c2 SRG |
6008 | |
6009 | list_for_each_entry_safe(bpage, tmp, &cpu_buffer->new_pages, list) { | |
6010 | list_del_init(&bpage->list); | |
6011 | free_buffer_page(bpage); | |
6012 | } | |
f9b94daa | 6013 | } |
f9b94daa TSV |
6014 | |
6015 | return err; | |
2808e31e TSV |
6016 | } |
6017 | EXPORT_SYMBOL_GPL(ring_buffer_subbuf_order_set); | |
6018 | ||
b32614c0 SAS |
6019 | /* |
6020 | * We only allocate new buffers, never free them if the CPU goes down. | |
6021 | * If we were to free the buffer, then the user would lose any trace that was in | |
6022 | * the buffer. | |
6023 | */ | |
6024 | int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node) | |
554f786e | 6025 | { |
13292494 | 6026 | struct trace_buffer *buffer; |
9b94a8fb SRRH |
6027 | long nr_pages_same; |
6028 | int cpu_i; | |
6029 | unsigned long nr_pages; | |
554f786e | 6030 | |
13292494 | 6031 | buffer = container_of(node, struct trace_buffer, node); |
b32614c0 SAS |
6032 | if (cpumask_test_cpu(cpu, buffer->cpumask)) |
6033 | return 0; | |
6034 | ||
6035 | nr_pages = 0; | |
6036 | nr_pages_same = 1; | |
6037 | /* check if all cpu sizes are same */ | |
6038 | for_each_buffer_cpu(buffer, cpu_i) { | |
6039 | /* fill in the size from first enabled cpu */ | |
6040 | if (nr_pages == 0) | |
6041 | nr_pages = buffer->buffers[cpu_i]->nr_pages; | |
6042 | if (nr_pages != buffer->buffers[cpu_i]->nr_pages) { | |
6043 | nr_pages_same = 0; | |
6044 | break; | |
554f786e | 6045 | } |
554f786e | 6046 | } |
b32614c0 SAS |
6047 | /* allocate minimum pages, user can later expand it */ |
6048 | if (!nr_pages_same) | |
6049 | nr_pages = 2; | |
6050 | buffer->buffers[cpu] = | |
6051 | rb_allocate_cpu_buffer(buffer, nr_pages, cpu); | |
6052 | if (!buffer->buffers[cpu]) { | |
6053 | WARN(1, "failed to allocate ring buffer on CPU %u\n", | |
6054 | cpu); | |
6055 | return -ENOMEM; | |
6056 | } | |
6057 | smp_wmb(); | |
6058 | cpumask_set_cpu(cpu, buffer->cpumask); | |
6059 | return 0; | |
554f786e | 6060 | } |
6c43e554 SRRH |
6061 | |
6062 | #ifdef CONFIG_RING_BUFFER_STARTUP_TEST | |
6063 | /* | |
6064 | * This is a basic integrity check of the ring buffer. | |
6065 | * Late in the boot cycle this test will run when configured in. | |
6066 | * It will kick off a thread per CPU that will go into a loop | |
6067 | * writing to the per cpu ring buffer various sizes of data. | |
6068 | * Some of the data will be large items, some small. | |
6069 | * | |
6070 | * Another thread is created that goes into a spin, sending out | |
6071 | * IPIs to the other CPUs to also write into the ring buffer. | |
6072 | * this is to test the nesting ability of the buffer. | |
6073 | * | |
6074 | * Basic stats are recorded and reported. If something in the | |
6075 | * ring buffer should happen that's not expected, a big warning | |
6076 | * is displayed and all ring buffers are disabled. | |
6077 | */ | |
6078 | static struct task_struct *rb_threads[NR_CPUS] __initdata; | |
6079 | ||
6080 | struct rb_test_data { | |
13292494 | 6081 | struct trace_buffer *buffer; |
6c43e554 SRRH |
6082 | unsigned long events; |
6083 | unsigned long bytes_written; | |
6084 | unsigned long bytes_alloc; | |
6085 | unsigned long bytes_dropped; | |
6086 | unsigned long events_nested; | |
6087 | unsigned long bytes_written_nested; | |
6088 | unsigned long bytes_alloc_nested; | |
6089 | unsigned long bytes_dropped_nested; | |
6090 | int min_size_nested; | |
6091 | int max_size_nested; | |
6092 | int max_size; | |
6093 | int min_size; | |
6094 | int cpu; | |
6095 | int cnt; | |
6096 | }; | |
6097 | ||
6098 | static struct rb_test_data rb_data[NR_CPUS] __initdata; | |
6099 | ||
6100 | /* 1 meg per cpu */ | |
6101 | #define RB_TEST_BUFFER_SIZE 1048576 | |
6102 | ||
6103 | static char rb_string[] __initdata = | |
6104 | "abcdefghijklmnopqrstuvwxyz1234567890!@#$%^&*()?+\\" | |
6105 | "?+|:';\",.<>/?abcdefghijklmnopqrstuvwxyz1234567890" | |
6106 | "!@#$%^&*()?+\\?+|:';\",.<>/?abcdefghijklmnopqrstuv"; | |
6107 | ||
6108 | static bool rb_test_started __initdata; | |
6109 | ||
6110 | struct rb_item { | |
6111 | int size; | |
6112 | char str[]; | |
6113 | }; | |
6114 | ||
6115 | static __init int rb_write_something(struct rb_test_data *data, bool nested) | |
6116 | { | |
6117 | struct ring_buffer_event *event; | |
6118 | struct rb_item *item; | |
6119 | bool started; | |
6120 | int event_len; | |
6121 | int size; | |
6122 | int len; | |
6123 | int cnt; | |
6124 | ||
6125 | /* Have nested writes different that what is written */ | |
6126 | cnt = data->cnt + (nested ? 27 : 0); | |
6127 | ||
6128 | /* Multiply cnt by ~e, to make some unique increment */ | |
40ed29b3 | 6129 | size = (cnt * 68 / 25) % (sizeof(rb_string) - 1); |
6c43e554 SRRH |
6130 | |
6131 | len = size + sizeof(struct rb_item); | |
6132 | ||
6133 | started = rb_test_started; | |
6134 | /* read rb_test_started before checking buffer enabled */ | |
6135 | smp_rmb(); | |
6136 | ||
6137 | event = ring_buffer_lock_reserve(data->buffer, len); | |
6138 | if (!event) { | |
6139 | /* Ignore dropped events before test starts. */ | |
6140 | if (started) { | |
6141 | if (nested) | |
6142 | data->bytes_dropped += len; | |
6143 | else | |
6144 | data->bytes_dropped_nested += len; | |
6145 | } | |
6146 | return len; | |
6147 | } | |
6148 | ||
6149 | event_len = ring_buffer_event_length(event); | |
6150 | ||
6151 | if (RB_WARN_ON(data->buffer, event_len < len)) | |
6152 | goto out; | |
6153 | ||
6154 | item = ring_buffer_event_data(event); | |
6155 | item->size = size; | |
6156 | memcpy(item->str, rb_string, size); | |
6157 | ||
6158 | if (nested) { | |
6159 | data->bytes_alloc_nested += event_len; | |
6160 | data->bytes_written_nested += len; | |
6161 | data->events_nested++; | |
6162 | if (!data->min_size_nested || len < data->min_size_nested) | |
6163 | data->min_size_nested = len; | |
6164 | if (len > data->max_size_nested) | |
6165 | data->max_size_nested = len; | |
6166 | } else { | |
6167 | data->bytes_alloc += event_len; | |
6168 | data->bytes_written += len; | |
6169 | data->events++; | |
6170 | if (!data->min_size || len < data->min_size) | |
6171 | data->max_size = len; | |
6172 | if (len > data->max_size) | |
6173 | data->max_size = len; | |
6174 | } | |
6175 | ||
6176 | out: | |
04aabc32 | 6177 | ring_buffer_unlock_commit(data->buffer); |
6c43e554 SRRH |
6178 | |
6179 | return 0; | |
6180 | } | |
6181 | ||
6182 | static __init int rb_test(void *arg) | |
6183 | { | |
6184 | struct rb_test_data *data = arg; | |
6185 | ||
6186 | while (!kthread_should_stop()) { | |
6187 | rb_write_something(data, false); | |
6188 | data->cnt++; | |
6189 | ||
6190 | set_current_state(TASK_INTERRUPTIBLE); | |
6191 | /* Now sleep between a min of 100-300us and a max of 1ms */ | |
6192 | usleep_range(((data->cnt % 3) + 1) * 100, 1000); | |
6193 | } | |
6194 | ||
6195 | return 0; | |
6196 | } | |
6197 | ||
6198 | static __init void rb_ipi(void *ignore) | |
6199 | { | |
6200 | struct rb_test_data *data; | |
6201 | int cpu = smp_processor_id(); | |
6202 | ||
6203 | data = &rb_data[cpu]; | |
6204 | rb_write_something(data, true); | |
6205 | } | |
6206 | ||
6207 | static __init int rb_hammer_test(void *arg) | |
6208 | { | |
6209 | while (!kthread_should_stop()) { | |
6210 | ||
6211 | /* Send an IPI to all cpus to write data! */ | |
6212 | smp_call_function(rb_ipi, NULL, 1); | |
6213 | /* No sleep, but for non preempt, let others run */ | |
6214 | schedule(); | |
6215 | } | |
6216 | ||
6217 | return 0; | |
6218 | } | |
6219 | ||
6220 | static __init int test_ringbuffer(void) | |
6221 | { | |
6222 | struct task_struct *rb_hammer; | |
13292494 | 6223 | struct trace_buffer *buffer; |
6c43e554 SRRH |
6224 | int cpu; |
6225 | int ret = 0; | |
6226 | ||
a356646a | 6227 | if (security_locked_down(LOCKDOWN_TRACEFS)) { |
ee195452 | 6228 | pr_warn("Lockdown is enabled, skipping ring buffer tests\n"); |
a356646a SRV |
6229 | return 0; |
6230 | } | |
6231 | ||
6c43e554 SRRH |
6232 | pr_info("Running ring buffer tests...\n"); |
6233 | ||
6234 | buffer = ring_buffer_alloc(RB_TEST_BUFFER_SIZE, RB_FL_OVERWRITE); | |
6235 | if (WARN_ON(!buffer)) | |
6236 | return 0; | |
6237 | ||
6238 | /* Disable buffer so that threads can't write to it yet */ | |
6239 | ring_buffer_record_off(buffer); | |
6240 | ||
6241 | for_each_online_cpu(cpu) { | |
6242 | rb_data[cpu].buffer = buffer; | |
6243 | rb_data[cpu].cpu = cpu; | |
6244 | rb_data[cpu].cnt = cpu; | |
64ed3a04 CH |
6245 | rb_threads[cpu] = kthread_run_on_cpu(rb_test, &rb_data[cpu], |
6246 | cpu, "rbtester/%u"); | |
62277de7 | 6247 | if (WARN_ON(IS_ERR(rb_threads[cpu]))) { |
6c43e554 | 6248 | pr_cont("FAILED\n"); |
62277de7 | 6249 | ret = PTR_ERR(rb_threads[cpu]); |
6c43e554 SRRH |
6250 | goto out_free; |
6251 | } | |
6c43e554 SRRH |
6252 | } |
6253 | ||
6254 | /* Now create the rb hammer! */ | |
6255 | rb_hammer = kthread_run(rb_hammer_test, NULL, "rbhammer"); | |
62277de7 | 6256 | if (WARN_ON(IS_ERR(rb_hammer))) { |
6c43e554 | 6257 | pr_cont("FAILED\n"); |
62277de7 | 6258 | ret = PTR_ERR(rb_hammer); |
6c43e554 SRRH |
6259 | goto out_free; |
6260 | } | |
6261 | ||
6262 | ring_buffer_record_on(buffer); | |
6263 | /* | |
6264 | * Show buffer is enabled before setting rb_test_started. | |
6265 | * Yes there's a small race window where events could be | |
6266 | * dropped and the thread wont catch it. But when a ring | |
6267 | * buffer gets enabled, there will always be some kind of | |
6268 | * delay before other CPUs see it. Thus, we don't care about | |
6269 | * those dropped events. We care about events dropped after | |
6270 | * the threads see that the buffer is active. | |
6271 | */ | |
6272 | smp_wmb(); | |
6273 | rb_test_started = true; | |
6274 | ||
6275 | set_current_state(TASK_INTERRUPTIBLE); | |
6276 | /* Just run for 10 seconds */; | |
6277 | schedule_timeout(10 * HZ); | |
6278 | ||
6279 | kthread_stop(rb_hammer); | |
6280 | ||
6281 | out_free: | |
6282 | for_each_online_cpu(cpu) { | |
6283 | if (!rb_threads[cpu]) | |
6284 | break; | |
6285 | kthread_stop(rb_threads[cpu]); | |
6286 | } | |
6287 | if (ret) { | |
6288 | ring_buffer_free(buffer); | |
6289 | return ret; | |
6290 | } | |
6291 | ||
6292 | /* Report! */ | |
6293 | pr_info("finished\n"); | |
6294 | for_each_online_cpu(cpu) { | |
6295 | struct ring_buffer_event *event; | |
6296 | struct rb_test_data *data = &rb_data[cpu]; | |
6297 | struct rb_item *item; | |
6298 | unsigned long total_events; | |
6299 | unsigned long total_dropped; | |
6300 | unsigned long total_written; | |
6301 | unsigned long total_alloc; | |
6302 | unsigned long total_read = 0; | |
6303 | unsigned long total_size = 0; | |
6304 | unsigned long total_len = 0; | |
6305 | unsigned long total_lost = 0; | |
6306 | unsigned long lost; | |
6307 | int big_event_size; | |
6308 | int small_event_size; | |
6309 | ||
6310 | ret = -1; | |
6311 | ||
6312 | total_events = data->events + data->events_nested; | |
6313 | total_written = data->bytes_written + data->bytes_written_nested; | |
6314 | total_alloc = data->bytes_alloc + data->bytes_alloc_nested; | |
6315 | total_dropped = data->bytes_dropped + data->bytes_dropped_nested; | |
6316 | ||
6317 | big_event_size = data->max_size + data->max_size_nested; | |
6318 | small_event_size = data->min_size + data->min_size_nested; | |
6319 | ||
6320 | pr_info("CPU %d:\n", cpu); | |
6321 | pr_info(" events: %ld\n", total_events); | |
6322 | pr_info(" dropped bytes: %ld\n", total_dropped); | |
6323 | pr_info(" alloced bytes: %ld\n", total_alloc); | |
6324 | pr_info(" written bytes: %ld\n", total_written); | |
6325 | pr_info(" biggest event: %d\n", big_event_size); | |
6326 | pr_info(" smallest event: %d\n", small_event_size); | |
6327 | ||
6328 | if (RB_WARN_ON(buffer, total_dropped)) | |
6329 | break; | |
6330 | ||
6331 | ret = 0; | |
6332 | ||
6333 | while ((event = ring_buffer_consume(buffer, cpu, NULL, &lost))) { | |
6334 | total_lost += lost; | |
6335 | item = ring_buffer_event_data(event); | |
6336 | total_len += ring_buffer_event_length(event); | |
6337 | total_size += item->size + sizeof(struct rb_item); | |
6338 | if (memcmp(&item->str[0], rb_string, item->size) != 0) { | |
6339 | pr_info("FAILED!\n"); | |
6340 | pr_info("buffer had: %.*s\n", item->size, item->str); | |
6341 | pr_info("expected: %.*s\n", item->size, rb_string); | |
6342 | RB_WARN_ON(buffer, 1); | |
6343 | ret = -1; | |
6344 | break; | |
6345 | } | |
6346 | total_read++; | |
6347 | } | |
6348 | if (ret) | |
6349 | break; | |
6350 | ||
6351 | ret = -1; | |
6352 | ||
6353 | pr_info(" read events: %ld\n", total_read); | |
6354 | pr_info(" lost events: %ld\n", total_lost); | |
6355 | pr_info(" total events: %ld\n", total_lost + total_read); | |
6356 | pr_info(" recorded len bytes: %ld\n", total_len); | |
6357 | pr_info(" recorded size bytes: %ld\n", total_size); | |
ed888241 | 6358 | if (total_lost) { |
6c43e554 SRRH |
6359 | pr_info(" With dropped events, record len and size may not match\n" |
6360 | " alloced and written from above\n"); | |
ed888241 | 6361 | } else { |
6c43e554 SRRH |
6362 | if (RB_WARN_ON(buffer, total_len != total_alloc || |
6363 | total_size != total_written)) | |
6364 | break; | |
6365 | } | |
6366 | if (RB_WARN_ON(buffer, total_lost + total_read != total_events)) | |
6367 | break; | |
6368 | ||
6369 | ret = 0; | |
6370 | } | |
6371 | if (!ret) | |
6372 | pr_info("Ring buffer PASSED!\n"); | |
6373 | ||
6374 | ring_buffer_free(buffer); | |
6375 | return 0; | |
6376 | } | |
6377 | ||
6378 | late_initcall(test_ringbuffer); | |
6379 | #endif /* CONFIG_RING_BUFFER_STARTUP_TEST */ |