Commit | Line | Data |
---|---|---|
7a8e76a3 SR |
1 | /* |
2 | * Generic ring buffer | |
3 | * | |
4 | * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com> | |
5 | */ | |
af658dca | 6 | #include <linux/trace_events.h> |
7a8e76a3 | 7 | #include <linux/ring_buffer.h> |
14131f2f | 8 | #include <linux/trace_clock.h> |
e6017571 | 9 | #include <linux/sched/clock.h> |
0b07436d | 10 | #include <linux/trace_seq.h> |
7a8e76a3 | 11 | #include <linux/spinlock.h> |
15693458 | 12 | #include <linux/irq_work.h> |
7a8e76a3 | 13 | #include <linux/uaccess.h> |
a81bd80a | 14 | #include <linux/hardirq.h> |
6c43e554 | 15 | #include <linux/kthread.h> /* for self test */ |
7a8e76a3 SR |
16 | #include <linux/module.h> |
17 | #include <linux/percpu.h> | |
18 | #include <linux/mutex.h> | |
6c43e554 | 19 | #include <linux/delay.h> |
5a0e3ad6 | 20 | #include <linux/slab.h> |
7a8e76a3 SR |
21 | #include <linux/init.h> |
22 | #include <linux/hash.h> | |
23 | #include <linux/list.h> | |
554f786e | 24 | #include <linux/cpu.h> |
7a8e76a3 | 25 | |
79615760 | 26 | #include <asm/local.h> |
182e9f5f | 27 | |
83f40318 VN |
28 | static void update_pages_handler(struct work_struct *work); |
29 | ||
d1b182a8 SR |
30 | /* |
31 | * The ring buffer header is special. We must manually up keep it. | |
32 | */ | |
33 | int ring_buffer_print_entry_header(struct trace_seq *s) | |
34 | { | |
c0cd93aa SRRH |
35 | trace_seq_puts(s, "# compressed entry header\n"); |
36 | trace_seq_puts(s, "\ttype_len : 5 bits\n"); | |
37 | trace_seq_puts(s, "\ttime_delta : 27 bits\n"); | |
38 | trace_seq_puts(s, "\tarray : 32 bits\n"); | |
39 | trace_seq_putc(s, '\n'); | |
40 | trace_seq_printf(s, "\tpadding : type == %d\n", | |
41 | RINGBUF_TYPE_PADDING); | |
42 | trace_seq_printf(s, "\ttime_extend : type == %d\n", | |
43 | RINGBUF_TYPE_TIME_EXTEND); | |
44 | trace_seq_printf(s, "\tdata max type_len == %d\n", | |
45 | RINGBUF_TYPE_DATA_TYPE_LEN_MAX); | |
46 | ||
47 | return !trace_seq_has_overflowed(s); | |
d1b182a8 SR |
48 | } |
49 | ||
5cc98548 SR |
50 | /* |
51 | * The ring buffer is made up of a list of pages. A separate list of pages is | |
52 | * allocated for each CPU. A writer may only write to a buffer that is | |
53 | * associated with the CPU it is currently executing on. A reader may read | |
54 | * from any per cpu buffer. | |
55 | * | |
56 | * The reader is special. For each per cpu buffer, the reader has its own | |
57 | * reader page. When a reader has read the entire reader page, this reader | |
58 | * page is swapped with another page in the ring buffer. | |
59 | * | |
60 | * Now, as long as the writer is off the reader page, the reader can do what | |
61 | * ever it wants with that page. The writer will never write to that page | |
62 | * again (as long as it is out of the ring buffer). | |
63 | * | |
64 | * Here's some silly ASCII art. | |
65 | * | |
66 | * +------+ | |
67 | * |reader| RING BUFFER | |
68 | * |page | | |
69 | * +------+ +---+ +---+ +---+ | |
70 | * | |-->| |-->| | | |
71 | * +---+ +---+ +---+ | |
72 | * ^ | | |
73 | * | | | |
74 | * +---------------+ | |
75 | * | |
76 | * | |
77 | * +------+ | |
78 | * |reader| RING BUFFER | |
79 | * |page |------------------v | |
80 | * +------+ +---+ +---+ +---+ | |
81 | * | |-->| |-->| | | |
82 | * +---+ +---+ +---+ | |
83 | * ^ | | |
84 | * | | | |
85 | * +---------------+ | |
86 | * | |
87 | * | |
88 | * +------+ | |
89 | * |reader| RING BUFFER | |
90 | * |page |------------------v | |
91 | * +------+ +---+ +---+ +---+ | |
92 | * ^ | |-->| |-->| | | |
93 | * | +---+ +---+ +---+ | |
94 | * | | | |
95 | * | | | |
96 | * +------------------------------+ | |
97 | * | |
98 | * | |
99 | * +------+ | |
100 | * |buffer| RING BUFFER | |
101 | * |page |------------------v | |
102 | * +------+ +---+ +---+ +---+ | |
103 | * ^ | | | |-->| | | |
104 | * | New +---+ +---+ +---+ | |
105 | * | Reader------^ | | |
106 | * | page | | |
107 | * +------------------------------+ | |
108 | * | |
109 | * | |
110 | * After we make this swap, the reader can hand this page off to the splice | |
111 | * code and be done with it. It can even allocate a new page if it needs to | |
112 | * and swap that into the ring buffer. | |
113 | * | |
114 | * We will be using cmpxchg soon to make all this lockless. | |
115 | * | |
116 | */ | |
117 | ||
499e5470 SR |
118 | /* Used for individual buffers (after the counter) */ |
119 | #define RB_BUFFER_OFF (1 << 20) | |
a3583244 | 120 | |
499e5470 | 121 | #define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data) |
033601a3 | 122 | |
e3d6bf0a | 123 | #define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array)) |
67d34724 | 124 | #define RB_ALIGNMENT 4U |
334d4169 | 125 | #define RB_MAX_SMALL_DATA (RB_ALIGNMENT * RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
c7b09308 | 126 | #define RB_EVNT_MIN_SIZE 8U /* two 32bit words */ |
334d4169 | 127 | |
649508f6 | 128 | #ifndef CONFIG_HAVE_64BIT_ALIGNED_ACCESS |
2271048d SR |
129 | # define RB_FORCE_8BYTE_ALIGNMENT 0 |
130 | # define RB_ARCH_ALIGNMENT RB_ALIGNMENT | |
131 | #else | |
132 | # define RB_FORCE_8BYTE_ALIGNMENT 1 | |
133 | # define RB_ARCH_ALIGNMENT 8U | |
134 | #endif | |
135 | ||
649508f6 JH |
136 | #define RB_ALIGN_DATA __aligned(RB_ARCH_ALIGNMENT) |
137 | ||
334d4169 LJ |
138 | /* define RINGBUF_TYPE_DATA for 'case RINGBUF_TYPE_DATA:' */ |
139 | #define RINGBUF_TYPE_DATA 0 ... RINGBUF_TYPE_DATA_TYPE_LEN_MAX | |
7a8e76a3 SR |
140 | |
141 | enum { | |
142 | RB_LEN_TIME_EXTEND = 8, | |
143 | RB_LEN_TIME_STAMP = 16, | |
144 | }; | |
145 | ||
69d1b839 SR |
146 | #define skip_time_extend(event) \ |
147 | ((struct ring_buffer_event *)((char *)event + RB_LEN_TIME_EXTEND)) | |
148 | ||
2d622719 TZ |
149 | static inline int rb_null_event(struct ring_buffer_event *event) |
150 | { | |
a1863c21 | 151 | return event->type_len == RINGBUF_TYPE_PADDING && !event->time_delta; |
2d622719 TZ |
152 | } |
153 | ||
154 | static void rb_event_set_padding(struct ring_buffer_event *event) | |
155 | { | |
a1863c21 | 156 | /* padding has a NULL time_delta */ |
334d4169 | 157 | event->type_len = RINGBUF_TYPE_PADDING; |
2d622719 TZ |
158 | event->time_delta = 0; |
159 | } | |
160 | ||
34a148bf | 161 | static unsigned |
2d622719 | 162 | rb_event_data_length(struct ring_buffer_event *event) |
7a8e76a3 SR |
163 | { |
164 | unsigned length; | |
165 | ||
334d4169 LJ |
166 | if (event->type_len) |
167 | length = event->type_len * RB_ALIGNMENT; | |
2d622719 TZ |
168 | else |
169 | length = event->array[0]; | |
170 | return length + RB_EVNT_HDR_SIZE; | |
171 | } | |
172 | ||
69d1b839 SR |
173 | /* |
174 | * Return the length of the given event. Will return | |
175 | * the length of the time extend if the event is a | |
176 | * time extend. | |
177 | */ | |
178 | static inline unsigned | |
2d622719 TZ |
179 | rb_event_length(struct ring_buffer_event *event) |
180 | { | |
334d4169 | 181 | switch (event->type_len) { |
7a8e76a3 | 182 | case RINGBUF_TYPE_PADDING: |
2d622719 TZ |
183 | if (rb_null_event(event)) |
184 | /* undefined */ | |
185 | return -1; | |
334d4169 | 186 | return event->array[0] + RB_EVNT_HDR_SIZE; |
7a8e76a3 SR |
187 | |
188 | case RINGBUF_TYPE_TIME_EXTEND: | |
189 | return RB_LEN_TIME_EXTEND; | |
190 | ||
191 | case RINGBUF_TYPE_TIME_STAMP: | |
192 | return RB_LEN_TIME_STAMP; | |
193 | ||
194 | case RINGBUF_TYPE_DATA: | |
2d622719 | 195 | return rb_event_data_length(event); |
7a8e76a3 SR |
196 | default: |
197 | BUG(); | |
198 | } | |
199 | /* not hit */ | |
200 | return 0; | |
201 | } | |
202 | ||
69d1b839 SR |
203 | /* |
204 | * Return total length of time extend and data, | |
205 | * or just the event length for all other events. | |
206 | */ | |
207 | static inline unsigned | |
208 | rb_event_ts_length(struct ring_buffer_event *event) | |
209 | { | |
210 | unsigned len = 0; | |
211 | ||
212 | if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) { | |
213 | /* time extends include the data event after it */ | |
214 | len = RB_LEN_TIME_EXTEND; | |
215 | event = skip_time_extend(event); | |
216 | } | |
217 | return len + rb_event_length(event); | |
218 | } | |
219 | ||
7a8e76a3 SR |
220 | /** |
221 | * ring_buffer_event_length - return the length of the event | |
222 | * @event: the event to get the length of | |
69d1b839 SR |
223 | * |
224 | * Returns the size of the data load of a data event. | |
225 | * If the event is something other than a data event, it | |
226 | * returns the size of the event itself. With the exception | |
227 | * of a TIME EXTEND, where it still returns the size of the | |
228 | * data load of the data event after it. | |
7a8e76a3 SR |
229 | */ |
230 | unsigned ring_buffer_event_length(struct ring_buffer_event *event) | |
231 | { | |
69d1b839 SR |
232 | unsigned length; |
233 | ||
234 | if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) | |
235 | event = skip_time_extend(event); | |
236 | ||
237 | length = rb_event_length(event); | |
334d4169 | 238 | if (event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
465634ad RR |
239 | return length; |
240 | length -= RB_EVNT_HDR_SIZE; | |
241 | if (length > RB_MAX_SMALL_DATA + sizeof(event->array[0])) | |
242 | length -= sizeof(event->array[0]); | |
243 | return length; | |
7a8e76a3 | 244 | } |
c4f50183 | 245 | EXPORT_SYMBOL_GPL(ring_buffer_event_length); |
7a8e76a3 SR |
246 | |
247 | /* inline for ring buffer fast paths */ | |
929ddbf3 | 248 | static __always_inline void * |
7a8e76a3 SR |
249 | rb_event_data(struct ring_buffer_event *event) |
250 | { | |
69d1b839 SR |
251 | if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) |
252 | event = skip_time_extend(event); | |
334d4169 | 253 | BUG_ON(event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX); |
7a8e76a3 | 254 | /* If length is in len field, then array[0] has the data */ |
334d4169 | 255 | if (event->type_len) |
7a8e76a3 SR |
256 | return (void *)&event->array[0]; |
257 | /* Otherwise length is in array[0] and array[1] has the data */ | |
258 | return (void *)&event->array[1]; | |
259 | } | |
260 | ||
261 | /** | |
262 | * ring_buffer_event_data - return the data of the event | |
263 | * @event: the event to get the data from | |
264 | */ | |
265 | void *ring_buffer_event_data(struct ring_buffer_event *event) | |
266 | { | |
267 | return rb_event_data(event); | |
268 | } | |
c4f50183 | 269 | EXPORT_SYMBOL_GPL(ring_buffer_event_data); |
7a8e76a3 SR |
270 | |
271 | #define for_each_buffer_cpu(buffer, cpu) \ | |
9e01c1b7 | 272 | for_each_cpu(cpu, buffer->cpumask) |
7a8e76a3 SR |
273 | |
274 | #define TS_SHIFT 27 | |
275 | #define TS_MASK ((1ULL << TS_SHIFT) - 1) | |
276 | #define TS_DELTA_TEST (~TS_MASK) | |
277 | ||
66a8cb95 SR |
278 | /* Flag when events were overwritten */ |
279 | #define RB_MISSED_EVENTS (1 << 31) | |
ff0ff84a SR |
280 | /* Missed count stored at end */ |
281 | #define RB_MISSED_STORED (1 << 30) | |
66a8cb95 | 282 | |
abc9b56d | 283 | struct buffer_data_page { |
e4c2ce82 | 284 | u64 time_stamp; /* page time stamp */ |
c3706f00 | 285 | local_t commit; /* write committed index */ |
649508f6 | 286 | unsigned char data[] RB_ALIGN_DATA; /* data of buffer page */ |
abc9b56d SR |
287 | }; |
288 | ||
77ae365e SR |
289 | /* |
290 | * Note, the buffer_page list must be first. The buffer pages | |
291 | * are allocated in cache lines, which means that each buffer | |
292 | * page will be at the beginning of a cache line, and thus | |
293 | * the least significant bits will be zero. We use this to | |
294 | * add flags in the list struct pointers, to make the ring buffer | |
295 | * lockless. | |
296 | */ | |
abc9b56d | 297 | struct buffer_page { |
778c55d4 | 298 | struct list_head list; /* list of buffer pages */ |
abc9b56d | 299 | local_t write; /* index for next write */ |
6f807acd | 300 | unsigned read; /* index for next read */ |
778c55d4 | 301 | local_t entries; /* entries on this page */ |
ff0ff84a | 302 | unsigned long real_end; /* real end of data */ |
abc9b56d | 303 | struct buffer_data_page *page; /* Actual data page */ |
7a8e76a3 SR |
304 | }; |
305 | ||
77ae365e SR |
306 | /* |
307 | * The buffer page counters, write and entries, must be reset | |
308 | * atomically when crossing page boundaries. To synchronize this | |
309 | * update, two counters are inserted into the number. One is | |
310 | * the actual counter for the write position or count on the page. | |
311 | * | |
312 | * The other is a counter of updaters. Before an update happens | |
313 | * the update partition of the counter is incremented. This will | |
314 | * allow the updater to update the counter atomically. | |
315 | * | |
316 | * The counter is 20 bits, and the state data is 12. | |
317 | */ | |
318 | #define RB_WRITE_MASK 0xfffff | |
319 | #define RB_WRITE_INTCNT (1 << 20) | |
320 | ||
044fa782 | 321 | static void rb_init_page(struct buffer_data_page *bpage) |
abc9b56d | 322 | { |
044fa782 | 323 | local_set(&bpage->commit, 0); |
abc9b56d SR |
324 | } |
325 | ||
474d32b6 SR |
326 | /** |
327 | * ring_buffer_page_len - the size of data on the page. | |
328 | * @page: The page to read | |
329 | * | |
330 | * Returns the amount of data on the page, including buffer page header. | |
331 | */ | |
ef7a4a16 SR |
332 | size_t ring_buffer_page_len(void *page) |
333 | { | |
474d32b6 SR |
334 | return local_read(&((struct buffer_data_page *)page)->commit) |
335 | + BUF_PAGE_HDR_SIZE; | |
ef7a4a16 SR |
336 | } |
337 | ||
ed56829c SR |
338 | /* |
339 | * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing | |
340 | * this issue out. | |
341 | */ | |
34a148bf | 342 | static void free_buffer_page(struct buffer_page *bpage) |
ed56829c | 343 | { |
34a148bf | 344 | free_page((unsigned long)bpage->page); |
e4c2ce82 | 345 | kfree(bpage); |
ed56829c SR |
346 | } |
347 | ||
7a8e76a3 SR |
348 | /* |
349 | * We need to fit the time_stamp delta into 27 bits. | |
350 | */ | |
351 | static inline int test_time_stamp(u64 delta) | |
352 | { | |
353 | if (delta & TS_DELTA_TEST) | |
354 | return 1; | |
355 | return 0; | |
356 | } | |
357 | ||
474d32b6 | 358 | #define BUF_PAGE_SIZE (PAGE_SIZE - BUF_PAGE_HDR_SIZE) |
7a8e76a3 | 359 | |
be957c44 SR |
360 | /* Max payload is BUF_PAGE_SIZE - header (8bytes) */ |
361 | #define BUF_MAX_DATA_SIZE (BUF_PAGE_SIZE - (sizeof(u32) * 2)) | |
362 | ||
d1b182a8 SR |
363 | int ring_buffer_print_page_header(struct trace_seq *s) |
364 | { | |
365 | struct buffer_data_page field; | |
c0cd93aa SRRH |
366 | |
367 | trace_seq_printf(s, "\tfield: u64 timestamp;\t" | |
368 | "offset:0;\tsize:%u;\tsigned:%u;\n", | |
369 | (unsigned int)sizeof(field.time_stamp), | |
370 | (unsigned int)is_signed_type(u64)); | |
371 | ||
372 | trace_seq_printf(s, "\tfield: local_t commit;\t" | |
373 | "offset:%u;\tsize:%u;\tsigned:%u;\n", | |
374 | (unsigned int)offsetof(typeof(field), commit), | |
375 | (unsigned int)sizeof(field.commit), | |
376 | (unsigned int)is_signed_type(long)); | |
377 | ||
378 | trace_seq_printf(s, "\tfield: int overwrite;\t" | |
379 | "offset:%u;\tsize:%u;\tsigned:%u;\n", | |
380 | (unsigned int)offsetof(typeof(field), commit), | |
381 | 1, | |
382 | (unsigned int)is_signed_type(long)); | |
383 | ||
384 | trace_seq_printf(s, "\tfield: char data;\t" | |
385 | "offset:%u;\tsize:%u;\tsigned:%u;\n", | |
386 | (unsigned int)offsetof(typeof(field), data), | |
387 | (unsigned int)BUF_PAGE_SIZE, | |
388 | (unsigned int)is_signed_type(char)); | |
389 | ||
390 | return !trace_seq_has_overflowed(s); | |
d1b182a8 SR |
391 | } |
392 | ||
15693458 SRRH |
393 | struct rb_irq_work { |
394 | struct irq_work work; | |
395 | wait_queue_head_t waiters; | |
1e0d6714 | 396 | wait_queue_head_t full_waiters; |
15693458 | 397 | bool waiters_pending; |
1e0d6714 SRRH |
398 | bool full_waiters_pending; |
399 | bool wakeup_full; | |
15693458 SRRH |
400 | }; |
401 | ||
fcc742ea SRRH |
402 | /* |
403 | * Structure to hold event state and handle nested events. | |
404 | */ | |
405 | struct rb_event_info { | |
406 | u64 ts; | |
407 | u64 delta; | |
408 | unsigned long length; | |
409 | struct buffer_page *tail_page; | |
410 | int add_timestamp; | |
411 | }; | |
412 | ||
a497adb4 SRRH |
413 | /* |
414 | * Used for which event context the event is in. | |
415 | * NMI = 0 | |
416 | * IRQ = 1 | |
417 | * SOFTIRQ = 2 | |
418 | * NORMAL = 3 | |
419 | * | |
420 | * See trace_recursive_lock() comment below for more details. | |
421 | */ | |
422 | enum { | |
423 | RB_CTX_NMI, | |
424 | RB_CTX_IRQ, | |
425 | RB_CTX_SOFTIRQ, | |
426 | RB_CTX_NORMAL, | |
427 | RB_CTX_MAX | |
428 | }; | |
429 | ||
7a8e76a3 SR |
430 | /* |
431 | * head_page == tail_page && head == tail then buffer is empty. | |
432 | */ | |
433 | struct ring_buffer_per_cpu { | |
434 | int cpu; | |
985023de | 435 | atomic_t record_disabled; |
7a8e76a3 | 436 | struct ring_buffer *buffer; |
5389f6fa | 437 | raw_spinlock_t reader_lock; /* serialize readers */ |
445c8951 | 438 | arch_spinlock_t lock; |
7a8e76a3 | 439 | struct lock_class_key lock_key; |
73a757e6 | 440 | struct buffer_data_page *free_page; |
9b94a8fb | 441 | unsigned long nr_pages; |
58a09ec6 | 442 | unsigned int current_context; |
3adc54fa | 443 | struct list_head *pages; |
6f807acd SR |
444 | struct buffer_page *head_page; /* read from head */ |
445 | struct buffer_page *tail_page; /* write to tail */ | |
c3706f00 | 446 | struct buffer_page *commit_page; /* committed pages */ |
d769041f | 447 | struct buffer_page *reader_page; |
66a8cb95 SR |
448 | unsigned long lost_events; |
449 | unsigned long last_overrun; | |
c64e148a | 450 | local_t entries_bytes; |
e4906eff | 451 | local_t entries; |
884bfe89 SP |
452 | local_t overrun; |
453 | local_t commit_overrun; | |
454 | local_t dropped_events; | |
fa743953 SR |
455 | local_t committing; |
456 | local_t commits; | |
77ae365e | 457 | unsigned long read; |
c64e148a | 458 | unsigned long read_bytes; |
7a8e76a3 SR |
459 | u64 write_stamp; |
460 | u64 read_stamp; | |
438ced17 | 461 | /* ring buffer pages to update, > 0 to add, < 0 to remove */ |
9b94a8fb | 462 | long nr_pages_to_update; |
438ced17 | 463 | struct list_head new_pages; /* new pages to add */ |
83f40318 | 464 | struct work_struct update_pages_work; |
05fdd70d | 465 | struct completion update_done; |
15693458 SRRH |
466 | |
467 | struct rb_irq_work irq_work; | |
7a8e76a3 SR |
468 | }; |
469 | ||
470 | struct ring_buffer { | |
7a8e76a3 SR |
471 | unsigned flags; |
472 | int cpus; | |
7a8e76a3 | 473 | atomic_t record_disabled; |
83f40318 | 474 | atomic_t resize_disabled; |
00f62f61 | 475 | cpumask_var_t cpumask; |
7a8e76a3 | 476 | |
1f8a6a10 PZ |
477 | struct lock_class_key *reader_lock_key; |
478 | ||
7a8e76a3 SR |
479 | struct mutex mutex; |
480 | ||
481 | struct ring_buffer_per_cpu **buffers; | |
554f786e | 482 | |
b32614c0 | 483 | struct hlist_node node; |
37886f6a | 484 | u64 (*clock)(void); |
15693458 SRRH |
485 | |
486 | struct rb_irq_work irq_work; | |
7a8e76a3 SR |
487 | }; |
488 | ||
489 | struct ring_buffer_iter { | |
490 | struct ring_buffer_per_cpu *cpu_buffer; | |
491 | unsigned long head; | |
492 | struct buffer_page *head_page; | |
492a74f4 SR |
493 | struct buffer_page *cache_reader_page; |
494 | unsigned long cache_read; | |
7a8e76a3 SR |
495 | u64 read_stamp; |
496 | }; | |
497 | ||
15693458 SRRH |
498 | /* |
499 | * rb_wake_up_waiters - wake up tasks waiting for ring buffer input | |
500 | * | |
501 | * Schedules a delayed work to wake up any task that is blocked on the | |
502 | * ring buffer waiters queue. | |
503 | */ | |
504 | static void rb_wake_up_waiters(struct irq_work *work) | |
505 | { | |
506 | struct rb_irq_work *rbwork = container_of(work, struct rb_irq_work, work); | |
507 | ||
508 | wake_up_all(&rbwork->waiters); | |
1e0d6714 SRRH |
509 | if (rbwork->wakeup_full) { |
510 | rbwork->wakeup_full = false; | |
511 | wake_up_all(&rbwork->full_waiters); | |
512 | } | |
15693458 SRRH |
513 | } |
514 | ||
515 | /** | |
516 | * ring_buffer_wait - wait for input to the ring buffer | |
517 | * @buffer: buffer to wait on | |
518 | * @cpu: the cpu buffer to wait on | |
e30f53aa | 519 | * @full: wait until a full page is available, if @cpu != RING_BUFFER_ALL_CPUS |
15693458 SRRH |
520 | * |
521 | * If @cpu == RING_BUFFER_ALL_CPUS then the task will wake up as soon | |
522 | * as data is added to any of the @buffer's cpu buffers. Otherwise | |
523 | * it will wait for data to be added to a specific cpu buffer. | |
524 | */ | |
e30f53aa | 525 | int ring_buffer_wait(struct ring_buffer *buffer, int cpu, bool full) |
15693458 | 526 | { |
e30f53aa | 527 | struct ring_buffer_per_cpu *uninitialized_var(cpu_buffer); |
15693458 SRRH |
528 | DEFINE_WAIT(wait); |
529 | struct rb_irq_work *work; | |
e30f53aa | 530 | int ret = 0; |
15693458 SRRH |
531 | |
532 | /* | |
533 | * Depending on what the caller is waiting for, either any | |
534 | * data in any cpu buffer, or a specific buffer, put the | |
535 | * caller on the appropriate wait queue. | |
536 | */ | |
1e0d6714 | 537 | if (cpu == RING_BUFFER_ALL_CPUS) { |
15693458 | 538 | work = &buffer->irq_work; |
1e0d6714 SRRH |
539 | /* Full only makes sense on per cpu reads */ |
540 | full = false; | |
541 | } else { | |
8b8b3683 SRRH |
542 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
543 | return -ENODEV; | |
15693458 SRRH |
544 | cpu_buffer = buffer->buffers[cpu]; |
545 | work = &cpu_buffer->irq_work; | |
546 | } | |
547 | ||
548 | ||
e30f53aa | 549 | while (true) { |
1e0d6714 SRRH |
550 | if (full) |
551 | prepare_to_wait(&work->full_waiters, &wait, TASK_INTERRUPTIBLE); | |
552 | else | |
553 | prepare_to_wait(&work->waiters, &wait, TASK_INTERRUPTIBLE); | |
e30f53aa RV |
554 | |
555 | /* | |
556 | * The events can happen in critical sections where | |
557 | * checking a work queue can cause deadlocks. | |
558 | * After adding a task to the queue, this flag is set | |
559 | * only to notify events to try to wake up the queue | |
560 | * using irq_work. | |
561 | * | |
562 | * We don't clear it even if the buffer is no longer | |
563 | * empty. The flag only causes the next event to run | |
564 | * irq_work to do the work queue wake up. The worse | |
565 | * that can happen if we race with !trace_empty() is that | |
566 | * an event will cause an irq_work to try to wake up | |
567 | * an empty queue. | |
568 | * | |
569 | * There's no reason to protect this flag either, as | |
570 | * the work queue and irq_work logic will do the necessary | |
571 | * synchronization for the wake ups. The only thing | |
572 | * that is necessary is that the wake up happens after | |
573 | * a task has been queued. It's OK for spurious wake ups. | |
574 | */ | |
1e0d6714 SRRH |
575 | if (full) |
576 | work->full_waiters_pending = true; | |
577 | else | |
578 | work->waiters_pending = true; | |
e30f53aa RV |
579 | |
580 | if (signal_pending(current)) { | |
581 | ret = -EINTR; | |
582 | break; | |
583 | } | |
584 | ||
585 | if (cpu == RING_BUFFER_ALL_CPUS && !ring_buffer_empty(buffer)) | |
586 | break; | |
587 | ||
588 | if (cpu != RING_BUFFER_ALL_CPUS && | |
589 | !ring_buffer_empty_cpu(buffer, cpu)) { | |
590 | unsigned long flags; | |
591 | bool pagebusy; | |
592 | ||
593 | if (!full) | |
594 | break; | |
595 | ||
596 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
597 | pagebusy = cpu_buffer->reader_page == cpu_buffer->commit_page; | |
598 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
599 | ||
600 | if (!pagebusy) | |
601 | break; | |
602 | } | |
15693458 | 603 | |
15693458 | 604 | schedule(); |
e30f53aa | 605 | } |
15693458 | 606 | |
1e0d6714 SRRH |
607 | if (full) |
608 | finish_wait(&work->full_waiters, &wait); | |
609 | else | |
610 | finish_wait(&work->waiters, &wait); | |
e30f53aa RV |
611 | |
612 | return ret; | |
15693458 SRRH |
613 | } |
614 | ||
615 | /** | |
616 | * ring_buffer_poll_wait - poll on buffer input | |
617 | * @buffer: buffer to wait on | |
618 | * @cpu: the cpu buffer to wait on | |
619 | * @filp: the file descriptor | |
620 | * @poll_table: The poll descriptor | |
621 | * | |
622 | * If @cpu == RING_BUFFER_ALL_CPUS then the task will wake up as soon | |
623 | * as data is added to any of the @buffer's cpu buffers. Otherwise | |
624 | * it will wait for data to be added to a specific cpu buffer. | |
625 | * | |
626 | * Returns POLLIN | POLLRDNORM if data exists in the buffers, | |
627 | * zero otherwise. | |
628 | */ | |
629 | int ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu, | |
630 | struct file *filp, poll_table *poll_table) | |
631 | { | |
632 | struct ring_buffer_per_cpu *cpu_buffer; | |
633 | struct rb_irq_work *work; | |
634 | ||
15693458 SRRH |
635 | if (cpu == RING_BUFFER_ALL_CPUS) |
636 | work = &buffer->irq_work; | |
637 | else { | |
6721cb60 SRRH |
638 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
639 | return -EINVAL; | |
640 | ||
15693458 SRRH |
641 | cpu_buffer = buffer->buffers[cpu]; |
642 | work = &cpu_buffer->irq_work; | |
643 | } | |
644 | ||
15693458 | 645 | poll_wait(filp, &work->waiters, poll_table); |
4ce97dbf JB |
646 | work->waiters_pending = true; |
647 | /* | |
648 | * There's a tight race between setting the waiters_pending and | |
649 | * checking if the ring buffer is empty. Once the waiters_pending bit | |
650 | * is set, the next event will wake the task up, but we can get stuck | |
651 | * if there's only a single event in. | |
652 | * | |
653 | * FIXME: Ideally, we need a memory barrier on the writer side as well, | |
654 | * but adding a memory barrier to all events will cause too much of a | |
655 | * performance hit in the fast path. We only need a memory barrier when | |
656 | * the buffer goes from empty to having content. But as this race is | |
657 | * extremely small, and it's not a problem if another event comes in, we | |
658 | * will fix it later. | |
659 | */ | |
660 | smp_mb(); | |
15693458 SRRH |
661 | |
662 | if ((cpu == RING_BUFFER_ALL_CPUS && !ring_buffer_empty(buffer)) || | |
663 | (cpu != RING_BUFFER_ALL_CPUS && !ring_buffer_empty_cpu(buffer, cpu))) | |
664 | return POLLIN | POLLRDNORM; | |
665 | return 0; | |
666 | } | |
667 | ||
f536aafc | 668 | /* buffer may be either ring_buffer or ring_buffer_per_cpu */ |
077c5407 SR |
669 | #define RB_WARN_ON(b, cond) \ |
670 | ({ \ | |
671 | int _____ret = unlikely(cond); \ | |
672 | if (_____ret) { \ | |
673 | if (__same_type(*(b), struct ring_buffer_per_cpu)) { \ | |
674 | struct ring_buffer_per_cpu *__b = \ | |
675 | (void *)b; \ | |
676 | atomic_inc(&__b->buffer->record_disabled); \ | |
677 | } else \ | |
678 | atomic_inc(&b->record_disabled); \ | |
679 | WARN_ON(1); \ | |
680 | } \ | |
681 | _____ret; \ | |
3e89c7bb | 682 | }) |
f536aafc | 683 | |
37886f6a SR |
684 | /* Up this if you want to test the TIME_EXTENTS and normalization */ |
685 | #define DEBUG_SHIFT 0 | |
686 | ||
6d3f1e12 | 687 | static inline u64 rb_time_stamp(struct ring_buffer *buffer) |
88eb0125 SR |
688 | { |
689 | /* shift to debug/test normalization and TIME_EXTENTS */ | |
690 | return buffer->clock() << DEBUG_SHIFT; | |
691 | } | |
692 | ||
37886f6a SR |
693 | u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu) |
694 | { | |
695 | u64 time; | |
696 | ||
697 | preempt_disable_notrace(); | |
6d3f1e12 | 698 | time = rb_time_stamp(buffer); |
37886f6a SR |
699 | preempt_enable_no_resched_notrace(); |
700 | ||
701 | return time; | |
702 | } | |
703 | EXPORT_SYMBOL_GPL(ring_buffer_time_stamp); | |
704 | ||
705 | void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer, | |
706 | int cpu, u64 *ts) | |
707 | { | |
708 | /* Just stupid testing the normalize function and deltas */ | |
709 | *ts >>= DEBUG_SHIFT; | |
710 | } | |
711 | EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp); | |
712 | ||
77ae365e SR |
713 | /* |
714 | * Making the ring buffer lockless makes things tricky. | |
715 | * Although writes only happen on the CPU that they are on, | |
716 | * and they only need to worry about interrupts. Reads can | |
717 | * happen on any CPU. | |
718 | * | |
719 | * The reader page is always off the ring buffer, but when the | |
720 | * reader finishes with a page, it needs to swap its page with | |
721 | * a new one from the buffer. The reader needs to take from | |
722 | * the head (writes go to the tail). But if a writer is in overwrite | |
723 | * mode and wraps, it must push the head page forward. | |
724 | * | |
725 | * Here lies the problem. | |
726 | * | |
727 | * The reader must be careful to replace only the head page, and | |
728 | * not another one. As described at the top of the file in the | |
729 | * ASCII art, the reader sets its old page to point to the next | |
730 | * page after head. It then sets the page after head to point to | |
731 | * the old reader page. But if the writer moves the head page | |
732 | * during this operation, the reader could end up with the tail. | |
733 | * | |
734 | * We use cmpxchg to help prevent this race. We also do something | |
735 | * special with the page before head. We set the LSB to 1. | |
736 | * | |
737 | * When the writer must push the page forward, it will clear the | |
738 | * bit that points to the head page, move the head, and then set | |
739 | * the bit that points to the new head page. | |
740 | * | |
741 | * We also don't want an interrupt coming in and moving the head | |
742 | * page on another writer. Thus we use the second LSB to catch | |
743 | * that too. Thus: | |
744 | * | |
745 | * head->list->prev->next bit 1 bit 0 | |
746 | * ------- ------- | |
747 | * Normal page 0 0 | |
748 | * Points to head page 0 1 | |
749 | * New head page 1 0 | |
750 | * | |
751 | * Note we can not trust the prev pointer of the head page, because: | |
752 | * | |
753 | * +----+ +-----+ +-----+ | |
754 | * | |------>| T |---X--->| N | | |
755 | * | |<------| | | | | |
756 | * +----+ +-----+ +-----+ | |
757 | * ^ ^ | | |
758 | * | +-----+ | | | |
759 | * +----------| R |----------+ | | |
760 | * | |<-----------+ | |
761 | * +-----+ | |
762 | * | |
763 | * Key: ---X--> HEAD flag set in pointer | |
764 | * T Tail page | |
765 | * R Reader page | |
766 | * N Next page | |
767 | * | |
768 | * (see __rb_reserve_next() to see where this happens) | |
769 | * | |
770 | * What the above shows is that the reader just swapped out | |
771 | * the reader page with a page in the buffer, but before it | |
772 | * could make the new header point back to the new page added | |
773 | * it was preempted by a writer. The writer moved forward onto | |
774 | * the new page added by the reader and is about to move forward | |
775 | * again. | |
776 | * | |
777 | * You can see, it is legitimate for the previous pointer of | |
778 | * the head (or any page) not to point back to itself. But only | |
779 | * temporarially. | |
780 | */ | |
781 | ||
782 | #define RB_PAGE_NORMAL 0UL | |
783 | #define RB_PAGE_HEAD 1UL | |
784 | #define RB_PAGE_UPDATE 2UL | |
785 | ||
786 | ||
787 | #define RB_FLAG_MASK 3UL | |
788 | ||
789 | /* PAGE_MOVED is not part of the mask */ | |
790 | #define RB_PAGE_MOVED 4UL | |
791 | ||
792 | /* | |
793 | * rb_list_head - remove any bit | |
794 | */ | |
795 | static struct list_head *rb_list_head(struct list_head *list) | |
796 | { | |
797 | unsigned long val = (unsigned long)list; | |
798 | ||
799 | return (struct list_head *)(val & ~RB_FLAG_MASK); | |
800 | } | |
801 | ||
802 | /* | |
6d3f1e12 | 803 | * rb_is_head_page - test if the given page is the head page |
77ae365e SR |
804 | * |
805 | * Because the reader may move the head_page pointer, we can | |
806 | * not trust what the head page is (it may be pointing to | |
807 | * the reader page). But if the next page is a header page, | |
808 | * its flags will be non zero. | |
809 | */ | |
42b16b3f | 810 | static inline int |
77ae365e SR |
811 | rb_is_head_page(struct ring_buffer_per_cpu *cpu_buffer, |
812 | struct buffer_page *page, struct list_head *list) | |
813 | { | |
814 | unsigned long val; | |
815 | ||
816 | val = (unsigned long)list->next; | |
817 | ||
818 | if ((val & ~RB_FLAG_MASK) != (unsigned long)&page->list) | |
819 | return RB_PAGE_MOVED; | |
820 | ||
821 | return val & RB_FLAG_MASK; | |
822 | } | |
823 | ||
824 | /* | |
825 | * rb_is_reader_page | |
826 | * | |
827 | * The unique thing about the reader page, is that, if the | |
828 | * writer is ever on it, the previous pointer never points | |
829 | * back to the reader page. | |
830 | */ | |
06ca3209 | 831 | static bool rb_is_reader_page(struct buffer_page *page) |
77ae365e SR |
832 | { |
833 | struct list_head *list = page->list.prev; | |
834 | ||
835 | return rb_list_head(list->next) != &page->list; | |
836 | } | |
837 | ||
838 | /* | |
839 | * rb_set_list_to_head - set a list_head to be pointing to head. | |
840 | */ | |
841 | static void rb_set_list_to_head(struct ring_buffer_per_cpu *cpu_buffer, | |
842 | struct list_head *list) | |
843 | { | |
844 | unsigned long *ptr; | |
845 | ||
846 | ptr = (unsigned long *)&list->next; | |
847 | *ptr |= RB_PAGE_HEAD; | |
848 | *ptr &= ~RB_PAGE_UPDATE; | |
849 | } | |
850 | ||
851 | /* | |
852 | * rb_head_page_activate - sets up head page | |
853 | */ | |
854 | static void rb_head_page_activate(struct ring_buffer_per_cpu *cpu_buffer) | |
855 | { | |
856 | struct buffer_page *head; | |
857 | ||
858 | head = cpu_buffer->head_page; | |
859 | if (!head) | |
860 | return; | |
861 | ||
862 | /* | |
863 | * Set the previous list pointer to have the HEAD flag. | |
864 | */ | |
865 | rb_set_list_to_head(cpu_buffer, head->list.prev); | |
866 | } | |
867 | ||
868 | static void rb_list_head_clear(struct list_head *list) | |
869 | { | |
870 | unsigned long *ptr = (unsigned long *)&list->next; | |
871 | ||
872 | *ptr &= ~RB_FLAG_MASK; | |
873 | } | |
874 | ||
875 | /* | |
876 | * rb_head_page_dactivate - clears head page ptr (for free list) | |
877 | */ | |
878 | static void | |
879 | rb_head_page_deactivate(struct ring_buffer_per_cpu *cpu_buffer) | |
880 | { | |
881 | struct list_head *hd; | |
882 | ||
883 | /* Go through the whole list and clear any pointers found. */ | |
884 | rb_list_head_clear(cpu_buffer->pages); | |
885 | ||
886 | list_for_each(hd, cpu_buffer->pages) | |
887 | rb_list_head_clear(hd); | |
888 | } | |
889 | ||
890 | static int rb_head_page_set(struct ring_buffer_per_cpu *cpu_buffer, | |
891 | struct buffer_page *head, | |
892 | struct buffer_page *prev, | |
893 | int old_flag, int new_flag) | |
894 | { | |
895 | struct list_head *list; | |
896 | unsigned long val = (unsigned long)&head->list; | |
897 | unsigned long ret; | |
898 | ||
899 | list = &prev->list; | |
900 | ||
901 | val &= ~RB_FLAG_MASK; | |
902 | ||
08a40816 SR |
903 | ret = cmpxchg((unsigned long *)&list->next, |
904 | val | old_flag, val | new_flag); | |
77ae365e SR |
905 | |
906 | /* check if the reader took the page */ | |
907 | if ((ret & ~RB_FLAG_MASK) != val) | |
908 | return RB_PAGE_MOVED; | |
909 | ||
910 | return ret & RB_FLAG_MASK; | |
911 | } | |
912 | ||
913 | static int rb_head_page_set_update(struct ring_buffer_per_cpu *cpu_buffer, | |
914 | struct buffer_page *head, | |
915 | struct buffer_page *prev, | |
916 | int old_flag) | |
917 | { | |
918 | return rb_head_page_set(cpu_buffer, head, prev, | |
919 | old_flag, RB_PAGE_UPDATE); | |
920 | } | |
921 | ||
922 | static int rb_head_page_set_head(struct ring_buffer_per_cpu *cpu_buffer, | |
923 | struct buffer_page *head, | |
924 | struct buffer_page *prev, | |
925 | int old_flag) | |
926 | { | |
927 | return rb_head_page_set(cpu_buffer, head, prev, | |
928 | old_flag, RB_PAGE_HEAD); | |
929 | } | |
930 | ||
931 | static int rb_head_page_set_normal(struct ring_buffer_per_cpu *cpu_buffer, | |
932 | struct buffer_page *head, | |
933 | struct buffer_page *prev, | |
934 | int old_flag) | |
935 | { | |
936 | return rb_head_page_set(cpu_buffer, head, prev, | |
937 | old_flag, RB_PAGE_NORMAL); | |
938 | } | |
939 | ||
940 | static inline void rb_inc_page(struct ring_buffer_per_cpu *cpu_buffer, | |
941 | struct buffer_page **bpage) | |
942 | { | |
943 | struct list_head *p = rb_list_head((*bpage)->list.next); | |
944 | ||
945 | *bpage = list_entry(p, struct buffer_page, list); | |
946 | } | |
947 | ||
948 | static struct buffer_page * | |
949 | rb_set_head_page(struct ring_buffer_per_cpu *cpu_buffer) | |
950 | { | |
951 | struct buffer_page *head; | |
952 | struct buffer_page *page; | |
953 | struct list_head *list; | |
954 | int i; | |
955 | ||
956 | if (RB_WARN_ON(cpu_buffer, !cpu_buffer->head_page)) | |
957 | return NULL; | |
958 | ||
959 | /* sanity check */ | |
960 | list = cpu_buffer->pages; | |
961 | if (RB_WARN_ON(cpu_buffer, rb_list_head(list->prev->next) != list)) | |
962 | return NULL; | |
963 | ||
964 | page = head = cpu_buffer->head_page; | |
965 | /* | |
966 | * It is possible that the writer moves the header behind | |
967 | * where we started, and we miss in one loop. | |
968 | * A second loop should grab the header, but we'll do | |
969 | * three loops just because I'm paranoid. | |
970 | */ | |
971 | for (i = 0; i < 3; i++) { | |
972 | do { | |
973 | if (rb_is_head_page(cpu_buffer, page, page->list.prev)) { | |
974 | cpu_buffer->head_page = page; | |
975 | return page; | |
976 | } | |
977 | rb_inc_page(cpu_buffer, &page); | |
978 | } while (page != head); | |
979 | } | |
980 | ||
981 | RB_WARN_ON(cpu_buffer, 1); | |
982 | ||
983 | return NULL; | |
984 | } | |
985 | ||
986 | static int rb_head_page_replace(struct buffer_page *old, | |
987 | struct buffer_page *new) | |
988 | { | |
989 | unsigned long *ptr = (unsigned long *)&old->list.prev->next; | |
990 | unsigned long val; | |
991 | unsigned long ret; | |
992 | ||
993 | val = *ptr & ~RB_FLAG_MASK; | |
994 | val |= RB_PAGE_HEAD; | |
995 | ||
08a40816 | 996 | ret = cmpxchg(ptr, val, (unsigned long)&new->list); |
77ae365e SR |
997 | |
998 | return ret == val; | |
999 | } | |
1000 | ||
1001 | /* | |
1002 | * rb_tail_page_update - move the tail page forward | |
77ae365e | 1003 | */ |
70004986 | 1004 | static void rb_tail_page_update(struct ring_buffer_per_cpu *cpu_buffer, |
77ae365e SR |
1005 | struct buffer_page *tail_page, |
1006 | struct buffer_page *next_page) | |
1007 | { | |
77ae365e SR |
1008 | unsigned long old_entries; |
1009 | unsigned long old_write; | |
77ae365e SR |
1010 | |
1011 | /* | |
1012 | * The tail page now needs to be moved forward. | |
1013 | * | |
1014 | * We need to reset the tail page, but without messing | |
1015 | * with possible erasing of data brought in by interrupts | |
1016 | * that have moved the tail page and are currently on it. | |
1017 | * | |
1018 | * We add a counter to the write field to denote this. | |
1019 | */ | |
1020 | old_write = local_add_return(RB_WRITE_INTCNT, &next_page->write); | |
1021 | old_entries = local_add_return(RB_WRITE_INTCNT, &next_page->entries); | |
1022 | ||
1023 | /* | |
1024 | * Just make sure we have seen our old_write and synchronize | |
1025 | * with any interrupts that come in. | |
1026 | */ | |
1027 | barrier(); | |
1028 | ||
1029 | /* | |
1030 | * If the tail page is still the same as what we think | |
1031 | * it is, then it is up to us to update the tail | |
1032 | * pointer. | |
1033 | */ | |
8573636e | 1034 | if (tail_page == READ_ONCE(cpu_buffer->tail_page)) { |
77ae365e SR |
1035 | /* Zero the write counter */ |
1036 | unsigned long val = old_write & ~RB_WRITE_MASK; | |
1037 | unsigned long eval = old_entries & ~RB_WRITE_MASK; | |
1038 | ||
1039 | /* | |
1040 | * This will only succeed if an interrupt did | |
1041 | * not come in and change it. In which case, we | |
1042 | * do not want to modify it. | |
da706d8b LJ |
1043 | * |
1044 | * We add (void) to let the compiler know that we do not care | |
1045 | * about the return value of these functions. We use the | |
1046 | * cmpxchg to only update if an interrupt did not already | |
1047 | * do it for us. If the cmpxchg fails, we don't care. | |
77ae365e | 1048 | */ |
da706d8b LJ |
1049 | (void)local_cmpxchg(&next_page->write, old_write, val); |
1050 | (void)local_cmpxchg(&next_page->entries, old_entries, eval); | |
77ae365e SR |
1051 | |
1052 | /* | |
1053 | * No need to worry about races with clearing out the commit. | |
1054 | * it only can increment when a commit takes place. But that | |
1055 | * only happens in the outer most nested commit. | |
1056 | */ | |
1057 | local_set(&next_page->page->commit, 0); | |
1058 | ||
70004986 SRRH |
1059 | /* Again, either we update tail_page or an interrupt does */ |
1060 | (void)cmpxchg(&cpu_buffer->tail_page, tail_page, next_page); | |
77ae365e | 1061 | } |
77ae365e SR |
1062 | } |
1063 | ||
1064 | static int rb_check_bpage(struct ring_buffer_per_cpu *cpu_buffer, | |
1065 | struct buffer_page *bpage) | |
1066 | { | |
1067 | unsigned long val = (unsigned long)bpage; | |
1068 | ||
1069 | if (RB_WARN_ON(cpu_buffer, val & RB_FLAG_MASK)) | |
1070 | return 1; | |
1071 | ||
1072 | return 0; | |
1073 | } | |
1074 | ||
1075 | /** | |
1076 | * rb_check_list - make sure a pointer to a list has the last bits zero | |
1077 | */ | |
1078 | static int rb_check_list(struct ring_buffer_per_cpu *cpu_buffer, | |
1079 | struct list_head *list) | |
1080 | { | |
1081 | if (RB_WARN_ON(cpu_buffer, rb_list_head(list->prev) != list->prev)) | |
1082 | return 1; | |
1083 | if (RB_WARN_ON(cpu_buffer, rb_list_head(list->next) != list->next)) | |
1084 | return 1; | |
1085 | return 0; | |
1086 | } | |
1087 | ||
7a8e76a3 | 1088 | /** |
d611851b | 1089 | * rb_check_pages - integrity check of buffer pages |
7a8e76a3 SR |
1090 | * @cpu_buffer: CPU buffer with pages to test |
1091 | * | |
c3706f00 | 1092 | * As a safety measure we check to make sure the data pages have not |
7a8e76a3 SR |
1093 | * been corrupted. |
1094 | */ | |
1095 | static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) | |
1096 | { | |
3adc54fa | 1097 | struct list_head *head = cpu_buffer->pages; |
044fa782 | 1098 | struct buffer_page *bpage, *tmp; |
7a8e76a3 | 1099 | |
308f7eeb SR |
1100 | /* Reset the head page if it exists */ |
1101 | if (cpu_buffer->head_page) | |
1102 | rb_set_head_page(cpu_buffer); | |
1103 | ||
77ae365e SR |
1104 | rb_head_page_deactivate(cpu_buffer); |
1105 | ||
3e89c7bb SR |
1106 | if (RB_WARN_ON(cpu_buffer, head->next->prev != head)) |
1107 | return -1; | |
1108 | if (RB_WARN_ON(cpu_buffer, head->prev->next != head)) | |
1109 | return -1; | |
7a8e76a3 | 1110 | |
77ae365e SR |
1111 | if (rb_check_list(cpu_buffer, head)) |
1112 | return -1; | |
1113 | ||
044fa782 | 1114 | list_for_each_entry_safe(bpage, tmp, head, list) { |
3e89c7bb | 1115 | if (RB_WARN_ON(cpu_buffer, |
044fa782 | 1116 | bpage->list.next->prev != &bpage->list)) |
3e89c7bb SR |
1117 | return -1; |
1118 | if (RB_WARN_ON(cpu_buffer, | |
044fa782 | 1119 | bpage->list.prev->next != &bpage->list)) |
3e89c7bb | 1120 | return -1; |
77ae365e SR |
1121 | if (rb_check_list(cpu_buffer, &bpage->list)) |
1122 | return -1; | |
7a8e76a3 SR |
1123 | } |
1124 | ||
77ae365e SR |
1125 | rb_head_page_activate(cpu_buffer); |
1126 | ||
7a8e76a3 SR |
1127 | return 0; |
1128 | } | |
1129 | ||
9b94a8fb | 1130 | static int __rb_allocate_pages(long nr_pages, struct list_head *pages, int cpu) |
7a8e76a3 | 1131 | { |
044fa782 | 1132 | struct buffer_page *bpage, *tmp; |
9b94a8fb | 1133 | long i; |
3adc54fa | 1134 | |
7a8e76a3 | 1135 | for (i = 0; i < nr_pages; i++) { |
7ea59064 | 1136 | struct page *page; |
d7ec4bfe | 1137 | /* |
84861885 JF |
1138 | * __GFP_RETRY_MAYFAIL flag makes sure that the allocation fails |
1139 | * gracefully without invoking oom-killer and the system is not | |
1140 | * destabilized. | |
d7ec4bfe | 1141 | */ |
044fa782 | 1142 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
84861885 | 1143 | GFP_KERNEL | __GFP_RETRY_MAYFAIL, |
438ced17 | 1144 | cpu_to_node(cpu)); |
044fa782 | 1145 | if (!bpage) |
e4c2ce82 | 1146 | goto free_pages; |
77ae365e | 1147 | |
438ced17 | 1148 | list_add(&bpage->list, pages); |
77ae365e | 1149 | |
438ced17 | 1150 | page = alloc_pages_node(cpu_to_node(cpu), |
84861885 | 1151 | GFP_KERNEL | __GFP_RETRY_MAYFAIL, 0); |
7ea59064 | 1152 | if (!page) |
7a8e76a3 | 1153 | goto free_pages; |
7ea59064 | 1154 | bpage->page = page_address(page); |
044fa782 | 1155 | rb_init_page(bpage->page); |
7a8e76a3 SR |
1156 | } |
1157 | ||
438ced17 VN |
1158 | return 0; |
1159 | ||
1160 | free_pages: | |
1161 | list_for_each_entry_safe(bpage, tmp, pages, list) { | |
1162 | list_del_init(&bpage->list); | |
1163 | free_buffer_page(bpage); | |
1164 | } | |
1165 | ||
1166 | return -ENOMEM; | |
1167 | } | |
1168 | ||
1169 | static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, | |
9b94a8fb | 1170 | unsigned long nr_pages) |
438ced17 VN |
1171 | { |
1172 | LIST_HEAD(pages); | |
1173 | ||
1174 | WARN_ON(!nr_pages); | |
1175 | ||
1176 | if (__rb_allocate_pages(nr_pages, &pages, cpu_buffer->cpu)) | |
1177 | return -ENOMEM; | |
1178 | ||
3adc54fa SR |
1179 | /* |
1180 | * The ring buffer page list is a circular list that does not | |
1181 | * start and end with a list head. All page list items point to | |
1182 | * other pages. | |
1183 | */ | |
1184 | cpu_buffer->pages = pages.next; | |
1185 | list_del(&pages); | |
7a8e76a3 | 1186 | |
438ced17 VN |
1187 | cpu_buffer->nr_pages = nr_pages; |
1188 | ||
7a8e76a3 SR |
1189 | rb_check_pages(cpu_buffer); |
1190 | ||
1191 | return 0; | |
7a8e76a3 SR |
1192 | } |
1193 | ||
1194 | static struct ring_buffer_per_cpu * | |
9b94a8fb | 1195 | rb_allocate_cpu_buffer(struct ring_buffer *buffer, long nr_pages, int cpu) |
7a8e76a3 SR |
1196 | { |
1197 | struct ring_buffer_per_cpu *cpu_buffer; | |
044fa782 | 1198 | struct buffer_page *bpage; |
7ea59064 | 1199 | struct page *page; |
7a8e76a3 SR |
1200 | int ret; |
1201 | ||
1202 | cpu_buffer = kzalloc_node(ALIGN(sizeof(*cpu_buffer), cache_line_size()), | |
1203 | GFP_KERNEL, cpu_to_node(cpu)); | |
1204 | if (!cpu_buffer) | |
1205 | return NULL; | |
1206 | ||
1207 | cpu_buffer->cpu = cpu; | |
1208 | cpu_buffer->buffer = buffer; | |
5389f6fa | 1209 | raw_spin_lock_init(&cpu_buffer->reader_lock); |
1f8a6a10 | 1210 | lockdep_set_class(&cpu_buffer->reader_lock, buffer->reader_lock_key); |
edc35bd7 | 1211 | cpu_buffer->lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; |
83f40318 | 1212 | INIT_WORK(&cpu_buffer->update_pages_work, update_pages_handler); |
05fdd70d | 1213 | init_completion(&cpu_buffer->update_done); |
15693458 | 1214 | init_irq_work(&cpu_buffer->irq_work.work, rb_wake_up_waiters); |
f1dc6725 | 1215 | init_waitqueue_head(&cpu_buffer->irq_work.waiters); |
1e0d6714 | 1216 | init_waitqueue_head(&cpu_buffer->irq_work.full_waiters); |
7a8e76a3 | 1217 | |
044fa782 | 1218 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
e4c2ce82 | 1219 | GFP_KERNEL, cpu_to_node(cpu)); |
044fa782 | 1220 | if (!bpage) |
e4c2ce82 SR |
1221 | goto fail_free_buffer; |
1222 | ||
77ae365e SR |
1223 | rb_check_bpage(cpu_buffer, bpage); |
1224 | ||
044fa782 | 1225 | cpu_buffer->reader_page = bpage; |
7ea59064 VN |
1226 | page = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL, 0); |
1227 | if (!page) | |
e4c2ce82 | 1228 | goto fail_free_reader; |
7ea59064 | 1229 | bpage->page = page_address(page); |
044fa782 | 1230 | rb_init_page(bpage->page); |
e4c2ce82 | 1231 | |
d769041f | 1232 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); |
44b99462 | 1233 | INIT_LIST_HEAD(&cpu_buffer->new_pages); |
d769041f | 1234 | |
438ced17 | 1235 | ret = rb_allocate_pages(cpu_buffer, nr_pages); |
7a8e76a3 | 1236 | if (ret < 0) |
d769041f | 1237 | goto fail_free_reader; |
7a8e76a3 SR |
1238 | |
1239 | cpu_buffer->head_page | |
3adc54fa | 1240 | = list_entry(cpu_buffer->pages, struct buffer_page, list); |
bf41a158 | 1241 | cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; |
7a8e76a3 | 1242 | |
77ae365e SR |
1243 | rb_head_page_activate(cpu_buffer); |
1244 | ||
7a8e76a3 SR |
1245 | return cpu_buffer; |
1246 | ||
d769041f SR |
1247 | fail_free_reader: |
1248 | free_buffer_page(cpu_buffer->reader_page); | |
1249 | ||
7a8e76a3 SR |
1250 | fail_free_buffer: |
1251 | kfree(cpu_buffer); | |
1252 | return NULL; | |
1253 | } | |
1254 | ||
1255 | static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) | |
1256 | { | |
3adc54fa | 1257 | struct list_head *head = cpu_buffer->pages; |
044fa782 | 1258 | struct buffer_page *bpage, *tmp; |
7a8e76a3 | 1259 | |
d769041f SR |
1260 | free_buffer_page(cpu_buffer->reader_page); |
1261 | ||
77ae365e SR |
1262 | rb_head_page_deactivate(cpu_buffer); |
1263 | ||
3adc54fa SR |
1264 | if (head) { |
1265 | list_for_each_entry_safe(bpage, tmp, head, list) { | |
1266 | list_del_init(&bpage->list); | |
1267 | free_buffer_page(bpage); | |
1268 | } | |
1269 | bpage = list_entry(head, struct buffer_page, list); | |
044fa782 | 1270 | free_buffer_page(bpage); |
7a8e76a3 | 1271 | } |
3adc54fa | 1272 | |
7a8e76a3 SR |
1273 | kfree(cpu_buffer); |
1274 | } | |
1275 | ||
1276 | /** | |
d611851b | 1277 | * __ring_buffer_alloc - allocate a new ring_buffer |
68814b58 | 1278 | * @size: the size in bytes per cpu that is needed. |
7a8e76a3 SR |
1279 | * @flags: attributes to set for the ring buffer. |
1280 | * | |
1281 | * Currently the only flag that is available is the RB_FL_OVERWRITE | |
1282 | * flag. This flag means that the buffer will overwrite old data | |
1283 | * when the buffer wraps. If this flag is not set, the buffer will | |
1284 | * drop data when the tail hits the head. | |
1285 | */ | |
1f8a6a10 PZ |
1286 | struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, |
1287 | struct lock_class_key *key) | |
7a8e76a3 SR |
1288 | { |
1289 | struct ring_buffer *buffer; | |
9b94a8fb | 1290 | long nr_pages; |
7a8e76a3 | 1291 | int bsize; |
9b94a8fb | 1292 | int cpu; |
b32614c0 | 1293 | int ret; |
7a8e76a3 SR |
1294 | |
1295 | /* keep it in its own cache line */ | |
1296 | buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()), | |
1297 | GFP_KERNEL); | |
1298 | if (!buffer) | |
1299 | return NULL; | |
1300 | ||
b18cc3de | 1301 | if (!zalloc_cpumask_var(&buffer->cpumask, GFP_KERNEL)) |
9e01c1b7 RR |
1302 | goto fail_free_buffer; |
1303 | ||
438ced17 | 1304 | nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
7a8e76a3 | 1305 | buffer->flags = flags; |
37886f6a | 1306 | buffer->clock = trace_clock_local; |
1f8a6a10 | 1307 | buffer->reader_lock_key = key; |
7a8e76a3 | 1308 | |
15693458 | 1309 | init_irq_work(&buffer->irq_work.work, rb_wake_up_waiters); |
f1dc6725 | 1310 | init_waitqueue_head(&buffer->irq_work.waiters); |
15693458 | 1311 | |
7a8e76a3 | 1312 | /* need at least two pages */ |
438ced17 VN |
1313 | if (nr_pages < 2) |
1314 | nr_pages = 2; | |
7a8e76a3 | 1315 | |
7a8e76a3 SR |
1316 | buffer->cpus = nr_cpu_ids; |
1317 | ||
1318 | bsize = sizeof(void *) * nr_cpu_ids; | |
1319 | buffer->buffers = kzalloc(ALIGN(bsize, cache_line_size()), | |
1320 | GFP_KERNEL); | |
1321 | if (!buffer->buffers) | |
9e01c1b7 | 1322 | goto fail_free_cpumask; |
7a8e76a3 | 1323 | |
b32614c0 SAS |
1324 | cpu = raw_smp_processor_id(); |
1325 | cpumask_set_cpu(cpu, buffer->cpumask); | |
1326 | buffer->buffers[cpu] = rb_allocate_cpu_buffer(buffer, nr_pages, cpu); | |
1327 | if (!buffer->buffers[cpu]) | |
1328 | goto fail_free_buffers; | |
7a8e76a3 | 1329 | |
b32614c0 SAS |
1330 | ret = cpuhp_state_add_instance(CPUHP_TRACE_RB_PREPARE, &buffer->node); |
1331 | if (ret < 0) | |
1332 | goto fail_free_buffers; | |
554f786e | 1333 | |
7a8e76a3 SR |
1334 | mutex_init(&buffer->mutex); |
1335 | ||
1336 | return buffer; | |
1337 | ||
1338 | fail_free_buffers: | |
1339 | for_each_buffer_cpu(buffer, cpu) { | |
1340 | if (buffer->buffers[cpu]) | |
1341 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
1342 | } | |
1343 | kfree(buffer->buffers); | |
1344 | ||
9e01c1b7 RR |
1345 | fail_free_cpumask: |
1346 | free_cpumask_var(buffer->cpumask); | |
1347 | ||
7a8e76a3 SR |
1348 | fail_free_buffer: |
1349 | kfree(buffer); | |
1350 | return NULL; | |
1351 | } | |
1f8a6a10 | 1352 | EXPORT_SYMBOL_GPL(__ring_buffer_alloc); |
7a8e76a3 SR |
1353 | |
1354 | /** | |
1355 | * ring_buffer_free - free a ring buffer. | |
1356 | * @buffer: the buffer to free. | |
1357 | */ | |
1358 | void | |
1359 | ring_buffer_free(struct ring_buffer *buffer) | |
1360 | { | |
1361 | int cpu; | |
1362 | ||
b32614c0 | 1363 | cpuhp_state_remove_instance(CPUHP_TRACE_RB_PREPARE, &buffer->node); |
554f786e | 1364 | |
7a8e76a3 SR |
1365 | for_each_buffer_cpu(buffer, cpu) |
1366 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
1367 | ||
bd3f0221 | 1368 | kfree(buffer->buffers); |
9e01c1b7 RR |
1369 | free_cpumask_var(buffer->cpumask); |
1370 | ||
7a8e76a3 SR |
1371 | kfree(buffer); |
1372 | } | |
c4f50183 | 1373 | EXPORT_SYMBOL_GPL(ring_buffer_free); |
7a8e76a3 | 1374 | |
37886f6a SR |
1375 | void ring_buffer_set_clock(struct ring_buffer *buffer, |
1376 | u64 (*clock)(void)) | |
1377 | { | |
1378 | buffer->clock = clock; | |
1379 | } | |
1380 | ||
7a8e76a3 SR |
1381 | static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer); |
1382 | ||
83f40318 VN |
1383 | static inline unsigned long rb_page_entries(struct buffer_page *bpage) |
1384 | { | |
1385 | return local_read(&bpage->entries) & RB_WRITE_MASK; | |
1386 | } | |
1387 | ||
1388 | static inline unsigned long rb_page_write(struct buffer_page *bpage) | |
1389 | { | |
1390 | return local_read(&bpage->write) & RB_WRITE_MASK; | |
1391 | } | |
1392 | ||
5040b4b7 | 1393 | static int |
9b94a8fb | 1394 | rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned long nr_pages) |
7a8e76a3 | 1395 | { |
83f40318 VN |
1396 | struct list_head *tail_page, *to_remove, *next_page; |
1397 | struct buffer_page *to_remove_page, *tmp_iter_page; | |
1398 | struct buffer_page *last_page, *first_page; | |
9b94a8fb | 1399 | unsigned long nr_removed; |
83f40318 VN |
1400 | unsigned long head_bit; |
1401 | int page_entries; | |
1402 | ||
1403 | head_bit = 0; | |
7a8e76a3 | 1404 | |
5389f6fa | 1405 | raw_spin_lock_irq(&cpu_buffer->reader_lock); |
83f40318 VN |
1406 | atomic_inc(&cpu_buffer->record_disabled); |
1407 | /* | |
1408 | * We don't race with the readers since we have acquired the reader | |
1409 | * lock. We also don't race with writers after disabling recording. | |
1410 | * This makes it easy to figure out the first and the last page to be | |
1411 | * removed from the list. We unlink all the pages in between including | |
1412 | * the first and last pages. This is done in a busy loop so that we | |
1413 | * lose the least number of traces. | |
1414 | * The pages are freed after we restart recording and unlock readers. | |
1415 | */ | |
1416 | tail_page = &cpu_buffer->tail_page->list; | |
77ae365e | 1417 | |
83f40318 VN |
1418 | /* |
1419 | * tail page might be on reader page, we remove the next page | |
1420 | * from the ring buffer | |
1421 | */ | |
1422 | if (cpu_buffer->tail_page == cpu_buffer->reader_page) | |
1423 | tail_page = rb_list_head(tail_page->next); | |
1424 | to_remove = tail_page; | |
1425 | ||
1426 | /* start of pages to remove */ | |
1427 | first_page = list_entry(rb_list_head(to_remove->next), | |
1428 | struct buffer_page, list); | |
1429 | ||
1430 | for (nr_removed = 0; nr_removed < nr_pages; nr_removed++) { | |
1431 | to_remove = rb_list_head(to_remove)->next; | |
1432 | head_bit |= (unsigned long)to_remove & RB_PAGE_HEAD; | |
7a8e76a3 | 1433 | } |
7a8e76a3 | 1434 | |
83f40318 | 1435 | next_page = rb_list_head(to_remove)->next; |
7a8e76a3 | 1436 | |
83f40318 VN |
1437 | /* |
1438 | * Now we remove all pages between tail_page and next_page. | |
1439 | * Make sure that we have head_bit value preserved for the | |
1440 | * next page | |
1441 | */ | |
1442 | tail_page->next = (struct list_head *)((unsigned long)next_page | | |
1443 | head_bit); | |
1444 | next_page = rb_list_head(next_page); | |
1445 | next_page->prev = tail_page; | |
1446 | ||
1447 | /* make sure pages points to a valid page in the ring buffer */ | |
1448 | cpu_buffer->pages = next_page; | |
1449 | ||
1450 | /* update head page */ | |
1451 | if (head_bit) | |
1452 | cpu_buffer->head_page = list_entry(next_page, | |
1453 | struct buffer_page, list); | |
1454 | ||
1455 | /* | |
1456 | * change read pointer to make sure any read iterators reset | |
1457 | * themselves | |
1458 | */ | |
1459 | cpu_buffer->read = 0; | |
1460 | ||
1461 | /* pages are removed, resume tracing and then free the pages */ | |
1462 | atomic_dec(&cpu_buffer->record_disabled); | |
5389f6fa | 1463 | raw_spin_unlock_irq(&cpu_buffer->reader_lock); |
83f40318 VN |
1464 | |
1465 | RB_WARN_ON(cpu_buffer, list_empty(cpu_buffer->pages)); | |
1466 | ||
1467 | /* last buffer page to remove */ | |
1468 | last_page = list_entry(rb_list_head(to_remove), struct buffer_page, | |
1469 | list); | |
1470 | tmp_iter_page = first_page; | |
1471 | ||
1472 | do { | |
1473 | to_remove_page = tmp_iter_page; | |
1474 | rb_inc_page(cpu_buffer, &tmp_iter_page); | |
1475 | ||
1476 | /* update the counters */ | |
1477 | page_entries = rb_page_entries(to_remove_page); | |
1478 | if (page_entries) { | |
1479 | /* | |
1480 | * If something was added to this page, it was full | |
1481 | * since it is not the tail page. So we deduct the | |
1482 | * bytes consumed in ring buffer from here. | |
48fdc72f | 1483 | * Increment overrun to account for the lost events. |
83f40318 | 1484 | */ |
48fdc72f | 1485 | local_add(page_entries, &cpu_buffer->overrun); |
83f40318 VN |
1486 | local_sub(BUF_PAGE_SIZE, &cpu_buffer->entries_bytes); |
1487 | } | |
1488 | ||
1489 | /* | |
1490 | * We have already removed references to this list item, just | |
1491 | * free up the buffer_page and its page | |
1492 | */ | |
1493 | free_buffer_page(to_remove_page); | |
1494 | nr_removed--; | |
1495 | ||
1496 | } while (to_remove_page != last_page); | |
1497 | ||
1498 | RB_WARN_ON(cpu_buffer, nr_removed); | |
5040b4b7 VN |
1499 | |
1500 | return nr_removed == 0; | |
7a8e76a3 SR |
1501 | } |
1502 | ||
5040b4b7 VN |
1503 | static int |
1504 | rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer) | |
7a8e76a3 | 1505 | { |
5040b4b7 VN |
1506 | struct list_head *pages = &cpu_buffer->new_pages; |
1507 | int retries, success; | |
7a8e76a3 | 1508 | |
5389f6fa | 1509 | raw_spin_lock_irq(&cpu_buffer->reader_lock); |
5040b4b7 VN |
1510 | /* |
1511 | * We are holding the reader lock, so the reader page won't be swapped | |
1512 | * in the ring buffer. Now we are racing with the writer trying to | |
1513 | * move head page and the tail page. | |
1514 | * We are going to adapt the reader page update process where: | |
1515 | * 1. We first splice the start and end of list of new pages between | |
1516 | * the head page and its previous page. | |
1517 | * 2. We cmpxchg the prev_page->next to point from head page to the | |
1518 | * start of new pages list. | |
1519 | * 3. Finally, we update the head->prev to the end of new list. | |
1520 | * | |
1521 | * We will try this process 10 times, to make sure that we don't keep | |
1522 | * spinning. | |
1523 | */ | |
1524 | retries = 10; | |
1525 | success = 0; | |
1526 | while (retries--) { | |
1527 | struct list_head *head_page, *prev_page, *r; | |
1528 | struct list_head *last_page, *first_page; | |
1529 | struct list_head *head_page_with_bit; | |
77ae365e | 1530 | |
5040b4b7 | 1531 | head_page = &rb_set_head_page(cpu_buffer)->list; |
54f7be5b SR |
1532 | if (!head_page) |
1533 | break; | |
5040b4b7 VN |
1534 | prev_page = head_page->prev; |
1535 | ||
1536 | first_page = pages->next; | |
1537 | last_page = pages->prev; | |
1538 | ||
1539 | head_page_with_bit = (struct list_head *) | |
1540 | ((unsigned long)head_page | RB_PAGE_HEAD); | |
1541 | ||
1542 | last_page->next = head_page_with_bit; | |
1543 | first_page->prev = prev_page; | |
1544 | ||
1545 | r = cmpxchg(&prev_page->next, head_page_with_bit, first_page); | |
1546 | ||
1547 | if (r == head_page_with_bit) { | |
1548 | /* | |
1549 | * yay, we replaced the page pointer to our new list, | |
1550 | * now, we just have to update to head page's prev | |
1551 | * pointer to point to end of list | |
1552 | */ | |
1553 | head_page->prev = last_page; | |
1554 | success = 1; | |
1555 | break; | |
1556 | } | |
7a8e76a3 | 1557 | } |
7a8e76a3 | 1558 | |
5040b4b7 VN |
1559 | if (success) |
1560 | INIT_LIST_HEAD(pages); | |
1561 | /* | |
1562 | * If we weren't successful in adding in new pages, warn and stop | |
1563 | * tracing | |
1564 | */ | |
1565 | RB_WARN_ON(cpu_buffer, !success); | |
5389f6fa | 1566 | raw_spin_unlock_irq(&cpu_buffer->reader_lock); |
5040b4b7 VN |
1567 | |
1568 | /* free pages if they weren't inserted */ | |
1569 | if (!success) { | |
1570 | struct buffer_page *bpage, *tmp; | |
1571 | list_for_each_entry_safe(bpage, tmp, &cpu_buffer->new_pages, | |
1572 | list) { | |
1573 | list_del_init(&bpage->list); | |
1574 | free_buffer_page(bpage); | |
1575 | } | |
1576 | } | |
1577 | return success; | |
7a8e76a3 SR |
1578 | } |
1579 | ||
83f40318 | 1580 | static void rb_update_pages(struct ring_buffer_per_cpu *cpu_buffer) |
438ced17 | 1581 | { |
5040b4b7 VN |
1582 | int success; |
1583 | ||
438ced17 | 1584 | if (cpu_buffer->nr_pages_to_update > 0) |
5040b4b7 | 1585 | success = rb_insert_pages(cpu_buffer); |
438ced17 | 1586 | else |
5040b4b7 VN |
1587 | success = rb_remove_pages(cpu_buffer, |
1588 | -cpu_buffer->nr_pages_to_update); | |
83f40318 | 1589 | |
5040b4b7 VN |
1590 | if (success) |
1591 | cpu_buffer->nr_pages += cpu_buffer->nr_pages_to_update; | |
83f40318 VN |
1592 | } |
1593 | ||
1594 | static void update_pages_handler(struct work_struct *work) | |
1595 | { | |
1596 | struct ring_buffer_per_cpu *cpu_buffer = container_of(work, | |
1597 | struct ring_buffer_per_cpu, update_pages_work); | |
1598 | rb_update_pages(cpu_buffer); | |
05fdd70d | 1599 | complete(&cpu_buffer->update_done); |
438ced17 VN |
1600 | } |
1601 | ||
7a8e76a3 SR |
1602 | /** |
1603 | * ring_buffer_resize - resize the ring buffer | |
1604 | * @buffer: the buffer to resize. | |
1605 | * @size: the new size. | |
d611851b | 1606 | * @cpu_id: the cpu buffer to resize |
7a8e76a3 | 1607 | * |
7a8e76a3 SR |
1608 | * Minimum size is 2 * BUF_PAGE_SIZE. |
1609 | * | |
83f40318 | 1610 | * Returns 0 on success and < 0 on failure. |
7a8e76a3 | 1611 | */ |
438ced17 VN |
1612 | int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, |
1613 | int cpu_id) | |
7a8e76a3 SR |
1614 | { |
1615 | struct ring_buffer_per_cpu *cpu_buffer; | |
9b94a8fb | 1616 | unsigned long nr_pages; |
83f40318 | 1617 | int cpu, err = 0; |
7a8e76a3 | 1618 | |
ee51a1de IM |
1619 | /* |
1620 | * Always succeed at resizing a non-existent buffer: | |
1621 | */ | |
1622 | if (!buffer) | |
1623 | return size; | |
1624 | ||
6a31e1f1 SR |
1625 | /* Make sure the requested buffer exists */ |
1626 | if (cpu_id != RING_BUFFER_ALL_CPUS && | |
1627 | !cpumask_test_cpu(cpu_id, buffer->cpumask)) | |
1628 | return size; | |
1629 | ||
59643d15 | 1630 | nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); |
7a8e76a3 SR |
1631 | |
1632 | /* we need a minimum of two pages */ | |
59643d15 SRRH |
1633 | if (nr_pages < 2) |
1634 | nr_pages = 2; | |
7a8e76a3 | 1635 | |
59643d15 | 1636 | size = nr_pages * BUF_PAGE_SIZE; |
18421015 | 1637 | |
83f40318 VN |
1638 | /* |
1639 | * Don't succeed if resizing is disabled, as a reader might be | |
1640 | * manipulating the ring buffer and is expecting a sane state while | |
1641 | * this is true. | |
1642 | */ | |
1643 | if (atomic_read(&buffer->resize_disabled)) | |
1644 | return -EBUSY; | |
18421015 | 1645 | |
83f40318 | 1646 | /* prevent another thread from changing buffer sizes */ |
7a8e76a3 | 1647 | mutex_lock(&buffer->mutex); |
7a8e76a3 | 1648 | |
438ced17 VN |
1649 | if (cpu_id == RING_BUFFER_ALL_CPUS) { |
1650 | /* calculate the pages to update */ | |
7a8e76a3 SR |
1651 | for_each_buffer_cpu(buffer, cpu) { |
1652 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 | 1653 | |
438ced17 VN |
1654 | cpu_buffer->nr_pages_to_update = nr_pages - |
1655 | cpu_buffer->nr_pages; | |
438ced17 VN |
1656 | /* |
1657 | * nothing more to do for removing pages or no update | |
1658 | */ | |
1659 | if (cpu_buffer->nr_pages_to_update <= 0) | |
1660 | continue; | |
d7ec4bfe | 1661 | /* |
438ced17 VN |
1662 | * to add pages, make sure all new pages can be |
1663 | * allocated without receiving ENOMEM | |
d7ec4bfe | 1664 | */ |
438ced17 VN |
1665 | INIT_LIST_HEAD(&cpu_buffer->new_pages); |
1666 | if (__rb_allocate_pages(cpu_buffer->nr_pages_to_update, | |
83f40318 | 1667 | &cpu_buffer->new_pages, cpu)) { |
438ced17 | 1668 | /* not enough memory for new pages */ |
83f40318 VN |
1669 | err = -ENOMEM; |
1670 | goto out_err; | |
1671 | } | |
1672 | } | |
1673 | ||
1674 | get_online_cpus(); | |
1675 | /* | |
1676 | * Fire off all the required work handlers | |
05fdd70d | 1677 | * We can't schedule on offline CPUs, but it's not necessary |
83f40318 VN |
1678 | * since we can change their buffer sizes without any race. |
1679 | */ | |
1680 | for_each_buffer_cpu(buffer, cpu) { | |
1681 | cpu_buffer = buffer->buffers[cpu]; | |
05fdd70d | 1682 | if (!cpu_buffer->nr_pages_to_update) |
83f40318 VN |
1683 | continue; |
1684 | ||
021c5b34 CM |
1685 | /* Can't run something on an offline CPU. */ |
1686 | if (!cpu_online(cpu)) { | |
f5eb5588 SRRH |
1687 | rb_update_pages(cpu_buffer); |
1688 | cpu_buffer->nr_pages_to_update = 0; | |
1689 | } else { | |
05fdd70d VN |
1690 | schedule_work_on(cpu, |
1691 | &cpu_buffer->update_pages_work); | |
f5eb5588 | 1692 | } |
7a8e76a3 | 1693 | } |
7a8e76a3 | 1694 | |
438ced17 VN |
1695 | /* wait for all the updates to complete */ |
1696 | for_each_buffer_cpu(buffer, cpu) { | |
1697 | cpu_buffer = buffer->buffers[cpu]; | |
05fdd70d | 1698 | if (!cpu_buffer->nr_pages_to_update) |
83f40318 VN |
1699 | continue; |
1700 | ||
05fdd70d VN |
1701 | if (cpu_online(cpu)) |
1702 | wait_for_completion(&cpu_buffer->update_done); | |
83f40318 | 1703 | cpu_buffer->nr_pages_to_update = 0; |
438ced17 | 1704 | } |
83f40318 VN |
1705 | |
1706 | put_online_cpus(); | |
438ced17 | 1707 | } else { |
8e49f418 VN |
1708 | /* Make sure this CPU has been intitialized */ |
1709 | if (!cpumask_test_cpu(cpu_id, buffer->cpumask)) | |
1710 | goto out; | |
1711 | ||
438ced17 | 1712 | cpu_buffer = buffer->buffers[cpu_id]; |
83f40318 | 1713 | |
438ced17 VN |
1714 | if (nr_pages == cpu_buffer->nr_pages) |
1715 | goto out; | |
7a8e76a3 | 1716 | |
438ced17 VN |
1717 | cpu_buffer->nr_pages_to_update = nr_pages - |
1718 | cpu_buffer->nr_pages; | |
1719 | ||
1720 | INIT_LIST_HEAD(&cpu_buffer->new_pages); | |
1721 | if (cpu_buffer->nr_pages_to_update > 0 && | |
1722 | __rb_allocate_pages(cpu_buffer->nr_pages_to_update, | |
83f40318 VN |
1723 | &cpu_buffer->new_pages, cpu_id)) { |
1724 | err = -ENOMEM; | |
1725 | goto out_err; | |
1726 | } | |
438ced17 | 1727 | |
83f40318 VN |
1728 | get_online_cpus(); |
1729 | ||
021c5b34 CM |
1730 | /* Can't run something on an offline CPU. */ |
1731 | if (!cpu_online(cpu_id)) | |
f5eb5588 SRRH |
1732 | rb_update_pages(cpu_buffer); |
1733 | else { | |
83f40318 VN |
1734 | schedule_work_on(cpu_id, |
1735 | &cpu_buffer->update_pages_work); | |
05fdd70d | 1736 | wait_for_completion(&cpu_buffer->update_done); |
f5eb5588 | 1737 | } |
83f40318 | 1738 | |
83f40318 | 1739 | cpu_buffer->nr_pages_to_update = 0; |
05fdd70d | 1740 | put_online_cpus(); |
438ced17 | 1741 | } |
7a8e76a3 SR |
1742 | |
1743 | out: | |
659f451f SR |
1744 | /* |
1745 | * The ring buffer resize can happen with the ring buffer | |
1746 | * enabled, so that the update disturbs the tracing as little | |
1747 | * as possible. But if the buffer is disabled, we do not need | |
1748 | * to worry about that, and we can take the time to verify | |
1749 | * that the buffer is not corrupt. | |
1750 | */ | |
1751 | if (atomic_read(&buffer->record_disabled)) { | |
1752 | atomic_inc(&buffer->record_disabled); | |
1753 | /* | |
1754 | * Even though the buffer was disabled, we must make sure | |
1755 | * that it is truly disabled before calling rb_check_pages. | |
1756 | * There could have been a race between checking | |
1757 | * record_disable and incrementing it. | |
1758 | */ | |
1759 | synchronize_sched(); | |
1760 | for_each_buffer_cpu(buffer, cpu) { | |
1761 | cpu_buffer = buffer->buffers[cpu]; | |
1762 | rb_check_pages(cpu_buffer); | |
1763 | } | |
1764 | atomic_dec(&buffer->record_disabled); | |
1765 | } | |
1766 | ||
7a8e76a3 | 1767 | mutex_unlock(&buffer->mutex); |
7a8e76a3 SR |
1768 | return size; |
1769 | ||
83f40318 | 1770 | out_err: |
438ced17 VN |
1771 | for_each_buffer_cpu(buffer, cpu) { |
1772 | struct buffer_page *bpage, *tmp; | |
83f40318 | 1773 | |
438ced17 | 1774 | cpu_buffer = buffer->buffers[cpu]; |
438ced17 | 1775 | cpu_buffer->nr_pages_to_update = 0; |
83f40318 | 1776 | |
438ced17 VN |
1777 | if (list_empty(&cpu_buffer->new_pages)) |
1778 | continue; | |
83f40318 | 1779 | |
438ced17 VN |
1780 | list_for_each_entry_safe(bpage, tmp, &cpu_buffer->new_pages, |
1781 | list) { | |
1782 | list_del_init(&bpage->list); | |
1783 | free_buffer_page(bpage); | |
1784 | } | |
7a8e76a3 | 1785 | } |
641d2f63 | 1786 | mutex_unlock(&buffer->mutex); |
83f40318 | 1787 | return err; |
7a8e76a3 | 1788 | } |
c4f50183 | 1789 | EXPORT_SYMBOL_GPL(ring_buffer_resize); |
7a8e76a3 | 1790 | |
750912fa DS |
1791 | void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val) |
1792 | { | |
1793 | mutex_lock(&buffer->mutex); | |
1794 | if (val) | |
1795 | buffer->flags |= RB_FL_OVERWRITE; | |
1796 | else | |
1797 | buffer->flags &= ~RB_FL_OVERWRITE; | |
1798 | mutex_unlock(&buffer->mutex); | |
1799 | } | |
1800 | EXPORT_SYMBOL_GPL(ring_buffer_change_overwrite); | |
1801 | ||
2289d567 | 1802 | static __always_inline void *__rb_page_index(struct buffer_page *bpage, unsigned index) |
7a8e76a3 | 1803 | { |
044fa782 | 1804 | return bpage->page->data + index; |
7a8e76a3 SR |
1805 | } |
1806 | ||
2289d567 | 1807 | static __always_inline struct ring_buffer_event * |
d769041f | 1808 | rb_reader_event(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 1809 | { |
6f807acd SR |
1810 | return __rb_page_index(cpu_buffer->reader_page, |
1811 | cpu_buffer->reader_page->read); | |
1812 | } | |
1813 | ||
2289d567 | 1814 | static __always_inline struct ring_buffer_event * |
7a8e76a3 SR |
1815 | rb_iter_head_event(struct ring_buffer_iter *iter) |
1816 | { | |
6f807acd | 1817 | return __rb_page_index(iter->head_page, iter->head); |
7a8e76a3 SR |
1818 | } |
1819 | ||
2289d567 | 1820 | static __always_inline unsigned rb_page_commit(struct buffer_page *bpage) |
bf41a158 | 1821 | { |
abc9b56d | 1822 | return local_read(&bpage->page->commit); |
bf41a158 SR |
1823 | } |
1824 | ||
25985edc | 1825 | /* Size is determined by what has been committed */ |
2289d567 | 1826 | static __always_inline unsigned rb_page_size(struct buffer_page *bpage) |
bf41a158 SR |
1827 | { |
1828 | return rb_page_commit(bpage); | |
1829 | } | |
1830 | ||
2289d567 | 1831 | static __always_inline unsigned |
bf41a158 SR |
1832 | rb_commit_index(struct ring_buffer_per_cpu *cpu_buffer) |
1833 | { | |
1834 | return rb_page_commit(cpu_buffer->commit_page); | |
1835 | } | |
1836 | ||
2289d567 | 1837 | static __always_inline unsigned |
bf41a158 SR |
1838 | rb_event_index(struct ring_buffer_event *event) |
1839 | { | |
1840 | unsigned long addr = (unsigned long)event; | |
1841 | ||
22f470f8 | 1842 | return (addr & ~PAGE_MASK) - BUF_PAGE_HDR_SIZE; |
bf41a158 SR |
1843 | } |
1844 | ||
34a148bf | 1845 | static void rb_inc_iter(struct ring_buffer_iter *iter) |
d769041f SR |
1846 | { |
1847 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
1848 | ||
1849 | /* | |
1850 | * The iterator could be on the reader page (it starts there). | |
1851 | * But the head could have moved, since the reader was | |
1852 | * found. Check for this case and assign the iterator | |
1853 | * to the head page instead of next. | |
1854 | */ | |
1855 | if (iter->head_page == cpu_buffer->reader_page) | |
77ae365e | 1856 | iter->head_page = rb_set_head_page(cpu_buffer); |
d769041f SR |
1857 | else |
1858 | rb_inc_page(cpu_buffer, &iter->head_page); | |
1859 | ||
abc9b56d | 1860 | iter->read_stamp = iter->head_page->page->time_stamp; |
7a8e76a3 SR |
1861 | iter->head = 0; |
1862 | } | |
1863 | ||
77ae365e SR |
1864 | /* |
1865 | * rb_handle_head_page - writer hit the head page | |
1866 | * | |
1867 | * Returns: +1 to retry page | |
1868 | * 0 to continue | |
1869 | * -1 on error | |
1870 | */ | |
1871 | static int | |
1872 | rb_handle_head_page(struct ring_buffer_per_cpu *cpu_buffer, | |
1873 | struct buffer_page *tail_page, | |
1874 | struct buffer_page *next_page) | |
1875 | { | |
1876 | struct buffer_page *new_head; | |
1877 | int entries; | |
1878 | int type; | |
1879 | int ret; | |
1880 | ||
1881 | entries = rb_page_entries(next_page); | |
1882 | ||
1883 | /* | |
1884 | * The hard part is here. We need to move the head | |
1885 | * forward, and protect against both readers on | |
1886 | * other CPUs and writers coming in via interrupts. | |
1887 | */ | |
1888 | type = rb_head_page_set_update(cpu_buffer, next_page, tail_page, | |
1889 | RB_PAGE_HEAD); | |
1890 | ||
1891 | /* | |
1892 | * type can be one of four: | |
1893 | * NORMAL - an interrupt already moved it for us | |
1894 | * HEAD - we are the first to get here. | |
1895 | * UPDATE - we are the interrupt interrupting | |
1896 | * a current move. | |
1897 | * MOVED - a reader on another CPU moved the next | |
1898 | * pointer to its reader page. Give up | |
1899 | * and try again. | |
1900 | */ | |
1901 | ||
1902 | switch (type) { | |
1903 | case RB_PAGE_HEAD: | |
1904 | /* | |
1905 | * We changed the head to UPDATE, thus | |
1906 | * it is our responsibility to update | |
1907 | * the counters. | |
1908 | */ | |
1909 | local_add(entries, &cpu_buffer->overrun); | |
c64e148a | 1910 | local_sub(BUF_PAGE_SIZE, &cpu_buffer->entries_bytes); |
77ae365e SR |
1911 | |
1912 | /* | |
1913 | * The entries will be zeroed out when we move the | |
1914 | * tail page. | |
1915 | */ | |
1916 | ||
1917 | /* still more to do */ | |
1918 | break; | |
1919 | ||
1920 | case RB_PAGE_UPDATE: | |
1921 | /* | |
1922 | * This is an interrupt that interrupt the | |
1923 | * previous update. Still more to do. | |
1924 | */ | |
1925 | break; | |
1926 | case RB_PAGE_NORMAL: | |
1927 | /* | |
1928 | * An interrupt came in before the update | |
1929 | * and processed this for us. | |
1930 | * Nothing left to do. | |
1931 | */ | |
1932 | return 1; | |
1933 | case RB_PAGE_MOVED: | |
1934 | /* | |
1935 | * The reader is on another CPU and just did | |
1936 | * a swap with our next_page. | |
1937 | * Try again. | |
1938 | */ | |
1939 | return 1; | |
1940 | default: | |
1941 | RB_WARN_ON(cpu_buffer, 1); /* WTF??? */ | |
1942 | return -1; | |
1943 | } | |
1944 | ||
1945 | /* | |
1946 | * Now that we are here, the old head pointer is | |
1947 | * set to UPDATE. This will keep the reader from | |
1948 | * swapping the head page with the reader page. | |
1949 | * The reader (on another CPU) will spin till | |
1950 | * we are finished. | |
1951 | * | |
1952 | * We just need to protect against interrupts | |
1953 | * doing the job. We will set the next pointer | |
1954 | * to HEAD. After that, we set the old pointer | |
1955 | * to NORMAL, but only if it was HEAD before. | |
1956 | * otherwise we are an interrupt, and only | |
1957 | * want the outer most commit to reset it. | |
1958 | */ | |
1959 | new_head = next_page; | |
1960 | rb_inc_page(cpu_buffer, &new_head); | |
1961 | ||
1962 | ret = rb_head_page_set_head(cpu_buffer, new_head, next_page, | |
1963 | RB_PAGE_NORMAL); | |
1964 | ||
1965 | /* | |
1966 | * Valid returns are: | |
1967 | * HEAD - an interrupt came in and already set it. | |
1968 | * NORMAL - One of two things: | |
1969 | * 1) We really set it. | |
1970 | * 2) A bunch of interrupts came in and moved | |
1971 | * the page forward again. | |
1972 | */ | |
1973 | switch (ret) { | |
1974 | case RB_PAGE_HEAD: | |
1975 | case RB_PAGE_NORMAL: | |
1976 | /* OK */ | |
1977 | break; | |
1978 | default: | |
1979 | RB_WARN_ON(cpu_buffer, 1); | |
1980 | return -1; | |
1981 | } | |
1982 | ||
1983 | /* | |
1984 | * It is possible that an interrupt came in, | |
1985 | * set the head up, then more interrupts came in | |
1986 | * and moved it again. When we get back here, | |
1987 | * the page would have been set to NORMAL but we | |
1988 | * just set it back to HEAD. | |
1989 | * | |
1990 | * How do you detect this? Well, if that happened | |
1991 | * the tail page would have moved. | |
1992 | */ | |
1993 | if (ret == RB_PAGE_NORMAL) { | |
8573636e SRRH |
1994 | struct buffer_page *buffer_tail_page; |
1995 | ||
1996 | buffer_tail_page = READ_ONCE(cpu_buffer->tail_page); | |
77ae365e SR |
1997 | /* |
1998 | * If the tail had moved passed next, then we need | |
1999 | * to reset the pointer. | |
2000 | */ | |
8573636e SRRH |
2001 | if (buffer_tail_page != tail_page && |
2002 | buffer_tail_page != next_page) | |
77ae365e SR |
2003 | rb_head_page_set_normal(cpu_buffer, new_head, |
2004 | next_page, | |
2005 | RB_PAGE_HEAD); | |
2006 | } | |
2007 | ||
2008 | /* | |
2009 | * If this was the outer most commit (the one that | |
2010 | * changed the original pointer from HEAD to UPDATE), | |
2011 | * then it is up to us to reset it to NORMAL. | |
2012 | */ | |
2013 | if (type == RB_PAGE_HEAD) { | |
2014 | ret = rb_head_page_set_normal(cpu_buffer, next_page, | |
2015 | tail_page, | |
2016 | RB_PAGE_UPDATE); | |
2017 | if (RB_WARN_ON(cpu_buffer, | |
2018 | ret != RB_PAGE_UPDATE)) | |
2019 | return -1; | |
2020 | } | |
2021 | ||
2022 | return 0; | |
2023 | } | |
2024 | ||
c7b09308 SR |
2025 | static inline void |
2026 | rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer, | |
fcc742ea | 2027 | unsigned long tail, struct rb_event_info *info) |
c7b09308 | 2028 | { |
fcc742ea | 2029 | struct buffer_page *tail_page = info->tail_page; |
c7b09308 | 2030 | struct ring_buffer_event *event; |
fcc742ea | 2031 | unsigned long length = info->length; |
c7b09308 SR |
2032 | |
2033 | /* | |
2034 | * Only the event that crossed the page boundary | |
2035 | * must fill the old tail_page with padding. | |
2036 | */ | |
2037 | if (tail >= BUF_PAGE_SIZE) { | |
b3230c8b SR |
2038 | /* |
2039 | * If the page was filled, then we still need | |
2040 | * to update the real_end. Reset it to zero | |
2041 | * and the reader will ignore it. | |
2042 | */ | |
2043 | if (tail == BUF_PAGE_SIZE) | |
2044 | tail_page->real_end = 0; | |
2045 | ||
c7b09308 SR |
2046 | local_sub(length, &tail_page->write); |
2047 | return; | |
2048 | } | |
2049 | ||
2050 | event = __rb_page_index(tail_page, tail); | |
2051 | ||
c64e148a VN |
2052 | /* account for padding bytes */ |
2053 | local_add(BUF_PAGE_SIZE - tail, &cpu_buffer->entries_bytes); | |
2054 | ||
ff0ff84a SR |
2055 | /* |
2056 | * Save the original length to the meta data. | |
2057 | * This will be used by the reader to add lost event | |
2058 | * counter. | |
2059 | */ | |
2060 | tail_page->real_end = tail; | |
2061 | ||
c7b09308 SR |
2062 | /* |
2063 | * If this event is bigger than the minimum size, then | |
2064 | * we need to be careful that we don't subtract the | |
2065 | * write counter enough to allow another writer to slip | |
2066 | * in on this page. | |
2067 | * We put in a discarded commit instead, to make sure | |
2068 | * that this space is not used again. | |
2069 | * | |
2070 | * If we are less than the minimum size, we don't need to | |
2071 | * worry about it. | |
2072 | */ | |
2073 | if (tail > (BUF_PAGE_SIZE - RB_EVNT_MIN_SIZE)) { | |
2074 | /* No room for any events */ | |
2075 | ||
2076 | /* Mark the rest of the page with padding */ | |
2077 | rb_event_set_padding(event); | |
2078 | ||
2079 | /* Set the write back to the previous setting */ | |
2080 | local_sub(length, &tail_page->write); | |
2081 | return; | |
2082 | } | |
2083 | ||
2084 | /* Put in a discarded event */ | |
2085 | event->array[0] = (BUF_PAGE_SIZE - tail) - RB_EVNT_HDR_SIZE; | |
2086 | event->type_len = RINGBUF_TYPE_PADDING; | |
2087 | /* time delta must be non zero */ | |
2088 | event->time_delta = 1; | |
c7b09308 SR |
2089 | |
2090 | /* Set write to end of buffer */ | |
2091 | length = (tail + length) - BUF_PAGE_SIZE; | |
2092 | local_sub(length, &tail_page->write); | |
2093 | } | |
6634ff26 | 2094 | |
4239c38f SRRH |
2095 | static inline void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer); |
2096 | ||
747e94ae SR |
2097 | /* |
2098 | * This is the slow path, force gcc not to inline it. | |
2099 | */ | |
2100 | static noinline struct ring_buffer_event * | |
6634ff26 | 2101 | rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer, |
fcc742ea | 2102 | unsigned long tail, struct rb_event_info *info) |
7a8e76a3 | 2103 | { |
fcc742ea | 2104 | struct buffer_page *tail_page = info->tail_page; |
5a50e33c | 2105 | struct buffer_page *commit_page = cpu_buffer->commit_page; |
7a8e76a3 | 2106 | struct ring_buffer *buffer = cpu_buffer->buffer; |
77ae365e SR |
2107 | struct buffer_page *next_page; |
2108 | int ret; | |
aa20ae84 SR |
2109 | |
2110 | next_page = tail_page; | |
2111 | ||
aa20ae84 SR |
2112 | rb_inc_page(cpu_buffer, &next_page); |
2113 | ||
aa20ae84 SR |
2114 | /* |
2115 | * If for some reason, we had an interrupt storm that made | |
2116 | * it all the way around the buffer, bail, and warn | |
2117 | * about it. | |
2118 | */ | |
2119 | if (unlikely(next_page == commit_page)) { | |
77ae365e | 2120 | local_inc(&cpu_buffer->commit_overrun); |
aa20ae84 SR |
2121 | goto out_reset; |
2122 | } | |
2123 | ||
77ae365e SR |
2124 | /* |
2125 | * This is where the fun begins! | |
2126 | * | |
2127 | * We are fighting against races between a reader that | |
2128 | * could be on another CPU trying to swap its reader | |
2129 | * page with the buffer head. | |
2130 | * | |
2131 | * We are also fighting against interrupts coming in and | |
2132 | * moving the head or tail on us as well. | |
2133 | * | |
2134 | * If the next page is the head page then we have filled | |
2135 | * the buffer, unless the commit page is still on the | |
2136 | * reader page. | |
2137 | */ | |
2138 | if (rb_is_head_page(cpu_buffer, next_page, &tail_page->list)) { | |
aa20ae84 | 2139 | |
77ae365e SR |
2140 | /* |
2141 | * If the commit is not on the reader page, then | |
2142 | * move the header page. | |
2143 | */ | |
2144 | if (!rb_is_reader_page(cpu_buffer->commit_page)) { | |
2145 | /* | |
2146 | * If we are not in overwrite mode, | |
2147 | * this is easy, just stop here. | |
2148 | */ | |
884bfe89 SP |
2149 | if (!(buffer->flags & RB_FL_OVERWRITE)) { |
2150 | local_inc(&cpu_buffer->dropped_events); | |
77ae365e | 2151 | goto out_reset; |
884bfe89 | 2152 | } |
77ae365e SR |
2153 | |
2154 | ret = rb_handle_head_page(cpu_buffer, | |
2155 | tail_page, | |
2156 | next_page); | |
2157 | if (ret < 0) | |
2158 | goto out_reset; | |
2159 | if (ret) | |
2160 | goto out_again; | |
2161 | } else { | |
2162 | /* | |
2163 | * We need to be careful here too. The | |
2164 | * commit page could still be on the reader | |
2165 | * page. We could have a small buffer, and | |
2166 | * have filled up the buffer with events | |
2167 | * from interrupts and such, and wrapped. | |
2168 | * | |
2169 | * Note, if the tail page is also the on the | |
2170 | * reader_page, we let it move out. | |
2171 | */ | |
2172 | if (unlikely((cpu_buffer->commit_page != | |
2173 | cpu_buffer->tail_page) && | |
2174 | (cpu_buffer->commit_page == | |
2175 | cpu_buffer->reader_page))) { | |
2176 | local_inc(&cpu_buffer->commit_overrun); | |
2177 | goto out_reset; | |
2178 | } | |
aa20ae84 SR |
2179 | } |
2180 | } | |
2181 | ||
70004986 | 2182 | rb_tail_page_update(cpu_buffer, tail_page, next_page); |
aa20ae84 | 2183 | |
77ae365e | 2184 | out_again: |
aa20ae84 | 2185 | |
fcc742ea | 2186 | rb_reset_tail(cpu_buffer, tail, info); |
aa20ae84 | 2187 | |
4239c38f SRRH |
2188 | /* Commit what we have for now. */ |
2189 | rb_end_commit(cpu_buffer); | |
2190 | /* rb_end_commit() decs committing */ | |
2191 | local_inc(&cpu_buffer->committing); | |
2192 | ||
aa20ae84 SR |
2193 | /* fail and let the caller try again */ |
2194 | return ERR_PTR(-EAGAIN); | |
2195 | ||
45141d46 | 2196 | out_reset: |
6f3b3440 | 2197 | /* reset write */ |
fcc742ea | 2198 | rb_reset_tail(cpu_buffer, tail, info); |
6f3b3440 | 2199 | |
bf41a158 | 2200 | return NULL; |
7a8e76a3 SR |
2201 | } |
2202 | ||
d90fd774 SRRH |
2203 | /* Slow path, do not inline */ |
2204 | static noinline struct ring_buffer_event * | |
2205 | rb_add_time_stamp(struct ring_buffer_event *event, u64 delta) | |
9826b273 | 2206 | { |
d90fd774 | 2207 | event->type_len = RINGBUF_TYPE_TIME_EXTEND; |
9826b273 | 2208 | |
d90fd774 SRRH |
2209 | /* Not the first event on the page? */ |
2210 | if (rb_event_index(event)) { | |
2211 | event->time_delta = delta & TS_MASK; | |
2212 | event->array[0] = delta >> TS_SHIFT; | |
2213 | } else { | |
2214 | /* nope, just zero it */ | |
2215 | event->time_delta = 0; | |
2216 | event->array[0] = 0; | |
2217 | } | |
a4543a2f | 2218 | |
d90fd774 SRRH |
2219 | return skip_time_extend(event); |
2220 | } | |
a4543a2f | 2221 | |
cdb2a0a9 | 2222 | static inline bool rb_event_is_commit(struct ring_buffer_per_cpu *cpu_buffer, |
b7dc42fd SRRH |
2223 | struct ring_buffer_event *event); |
2224 | ||
d90fd774 SRRH |
2225 | /** |
2226 | * rb_update_event - update event type and data | |
2227 | * @event: the event to update | |
2228 | * @type: the type of event | |
2229 | * @length: the size of the event field in the ring buffer | |
2230 | * | |
2231 | * Update the type and data fields of the event. The length | |
2232 | * is the actual size that is written to the ring buffer, | |
2233 | * and with this, we can determine what to place into the | |
2234 | * data field. | |
2235 | */ | |
b7dc42fd | 2236 | static void |
d90fd774 SRRH |
2237 | rb_update_event(struct ring_buffer_per_cpu *cpu_buffer, |
2238 | struct ring_buffer_event *event, | |
2239 | struct rb_event_info *info) | |
2240 | { | |
2241 | unsigned length = info->length; | |
2242 | u64 delta = info->delta; | |
a4543a2f | 2243 | |
b7dc42fd SRRH |
2244 | /* Only a commit updates the timestamp */ |
2245 | if (unlikely(!rb_event_is_commit(cpu_buffer, event))) | |
2246 | delta = 0; | |
2247 | ||
a4543a2f | 2248 | /* |
d90fd774 SRRH |
2249 | * If we need to add a timestamp, then we |
2250 | * add it to the start of the resevered space. | |
a4543a2f | 2251 | */ |
d90fd774 SRRH |
2252 | if (unlikely(info->add_timestamp)) { |
2253 | event = rb_add_time_stamp(event, delta); | |
2254 | length -= RB_LEN_TIME_EXTEND; | |
2255 | delta = 0; | |
a4543a2f SRRH |
2256 | } |
2257 | ||
d90fd774 SRRH |
2258 | event->time_delta = delta; |
2259 | length -= RB_EVNT_HDR_SIZE; | |
2260 | if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) { | |
2261 | event->type_len = 0; | |
2262 | event->array[0] = length; | |
2263 | } else | |
2264 | event->type_len = DIV_ROUND_UP(length, RB_ALIGNMENT); | |
2265 | } | |
2266 | ||
2267 | static unsigned rb_calculate_event_length(unsigned length) | |
2268 | { | |
2269 | struct ring_buffer_event event; /* Used only for sizeof array */ | |
2270 | ||
2271 | /* zero length can cause confusions */ | |
2272 | if (!length) | |
2273 | length++; | |
2274 | ||
2275 | if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) | |
2276 | length += sizeof(event.array[0]); | |
2277 | ||
2278 | length += RB_EVNT_HDR_SIZE; | |
2279 | length = ALIGN(length, RB_ARCH_ALIGNMENT); | |
2280 | ||
2281 | /* | |
2282 | * In case the time delta is larger than the 27 bits for it | |
2283 | * in the header, we need to add a timestamp. If another | |
2284 | * event comes in when trying to discard this one to increase | |
2285 | * the length, then the timestamp will be added in the allocated | |
2286 | * space of this event. If length is bigger than the size needed | |
2287 | * for the TIME_EXTEND, then padding has to be used. The events | |
2288 | * length must be either RB_LEN_TIME_EXTEND, or greater than or equal | |
2289 | * to RB_LEN_TIME_EXTEND + 8, as 8 is the minimum size for padding. | |
2290 | * As length is a multiple of 4, we only need to worry if it | |
2291 | * is 12 (RB_LEN_TIME_EXTEND + 4). | |
2292 | */ | |
2293 | if (length == RB_LEN_TIME_EXTEND + RB_ALIGNMENT) | |
2294 | length += RB_ALIGNMENT; | |
2295 | ||
2296 | return length; | |
2297 | } | |
2298 | ||
2299 | #ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK | |
2300 | static inline bool sched_clock_stable(void) | |
2301 | { | |
2302 | return true; | |
2303 | } | |
2304 | #endif | |
2305 | ||
2306 | static inline int | |
2307 | rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer, | |
2308 | struct ring_buffer_event *event) | |
2309 | { | |
2310 | unsigned long new_index, old_index; | |
2311 | struct buffer_page *bpage; | |
2312 | unsigned long index; | |
2313 | unsigned long addr; | |
2314 | ||
2315 | new_index = rb_event_index(event); | |
2316 | old_index = new_index + rb_event_ts_length(event); | |
2317 | addr = (unsigned long)event; | |
2318 | addr &= PAGE_MASK; | |
2319 | ||
8573636e | 2320 | bpage = READ_ONCE(cpu_buffer->tail_page); |
d90fd774 SRRH |
2321 | |
2322 | if (bpage->page == (void *)addr && rb_page_write(bpage) == old_index) { | |
2323 | unsigned long write_mask = | |
2324 | local_read(&bpage->write) & ~RB_WRITE_MASK; | |
2325 | unsigned long event_length = rb_event_length(event); | |
2326 | /* | |
2327 | * This is on the tail page. It is possible that | |
2328 | * a write could come in and move the tail page | |
2329 | * and write to the next page. That is fine | |
2330 | * because we just shorten what is on this page. | |
2331 | */ | |
2332 | old_index += write_mask; | |
2333 | new_index += write_mask; | |
2334 | index = local_cmpxchg(&bpage->write, old_index, new_index); | |
2335 | if (index == old_index) { | |
2336 | /* update counters */ | |
2337 | local_sub(event_length, &cpu_buffer->entries_bytes); | |
2338 | return 1; | |
2339 | } | |
2340 | } | |
2341 | ||
2342 | /* could not discard */ | |
2343 | return 0; | |
2344 | } | |
2345 | ||
2346 | static void rb_start_commit(struct ring_buffer_per_cpu *cpu_buffer) | |
2347 | { | |
2348 | local_inc(&cpu_buffer->committing); | |
2349 | local_inc(&cpu_buffer->commits); | |
2350 | } | |
2351 | ||
38e11df1 | 2352 | static __always_inline void |
d90fd774 SRRH |
2353 | rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) |
2354 | { | |
2355 | unsigned long max_count; | |
2356 | ||
2357 | /* | |
2358 | * We only race with interrupts and NMIs on this CPU. | |
2359 | * If we own the commit event, then we can commit | |
2360 | * all others that interrupted us, since the interruptions | |
2361 | * are in stack format (they finish before they come | |
2362 | * back to us). This allows us to do a simple loop to | |
2363 | * assign the commit to the tail. | |
2364 | */ | |
2365 | again: | |
2366 | max_count = cpu_buffer->nr_pages * 100; | |
2367 | ||
8573636e | 2368 | while (cpu_buffer->commit_page != READ_ONCE(cpu_buffer->tail_page)) { |
d90fd774 SRRH |
2369 | if (RB_WARN_ON(cpu_buffer, !(--max_count))) |
2370 | return; | |
2371 | if (RB_WARN_ON(cpu_buffer, | |
2372 | rb_is_reader_page(cpu_buffer->tail_page))) | |
2373 | return; | |
2374 | local_set(&cpu_buffer->commit_page->page->commit, | |
2375 | rb_page_write(cpu_buffer->commit_page)); | |
2376 | rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); | |
70004986 SRRH |
2377 | /* Only update the write stamp if the page has an event */ |
2378 | if (rb_page_write(cpu_buffer->commit_page)) | |
2379 | cpu_buffer->write_stamp = | |
2380 | cpu_buffer->commit_page->page->time_stamp; | |
d90fd774 SRRH |
2381 | /* add barrier to keep gcc from optimizing too much */ |
2382 | barrier(); | |
2383 | } | |
2384 | while (rb_commit_index(cpu_buffer) != | |
2385 | rb_page_write(cpu_buffer->commit_page)) { | |
2386 | ||
2387 | local_set(&cpu_buffer->commit_page->page->commit, | |
2388 | rb_page_write(cpu_buffer->commit_page)); | |
2389 | RB_WARN_ON(cpu_buffer, | |
2390 | local_read(&cpu_buffer->commit_page->page->commit) & | |
2391 | ~RB_WRITE_MASK); | |
2392 | barrier(); | |
2393 | } | |
2394 | ||
2395 | /* again, keep gcc from optimizing */ | |
2396 | barrier(); | |
2397 | ||
2398 | /* | |
2399 | * If an interrupt came in just after the first while loop | |
2400 | * and pushed the tail page forward, we will be left with | |
2401 | * a dangling commit that will never go forward. | |
2402 | */ | |
8573636e | 2403 | if (unlikely(cpu_buffer->commit_page != READ_ONCE(cpu_buffer->tail_page))) |
d90fd774 SRRH |
2404 | goto again; |
2405 | } | |
2406 | ||
38e11df1 | 2407 | static __always_inline void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer) |
d90fd774 SRRH |
2408 | { |
2409 | unsigned long commits; | |
2410 | ||
2411 | if (RB_WARN_ON(cpu_buffer, | |
2412 | !local_read(&cpu_buffer->committing))) | |
2413 | return; | |
2414 | ||
2415 | again: | |
2416 | commits = local_read(&cpu_buffer->commits); | |
2417 | /* synchronize with interrupts */ | |
2418 | barrier(); | |
2419 | if (local_read(&cpu_buffer->committing) == 1) | |
2420 | rb_set_commit_to_write(cpu_buffer); | |
2421 | ||
2422 | local_dec(&cpu_buffer->committing); | |
2423 | ||
2424 | /* synchronize with interrupts */ | |
2425 | barrier(); | |
2426 | ||
2427 | /* | |
2428 | * Need to account for interrupts coming in between the | |
2429 | * updating of the commit page and the clearing of the | |
2430 | * committing counter. | |
2431 | */ | |
2432 | if (unlikely(local_read(&cpu_buffer->commits) != commits) && | |
2433 | !local_read(&cpu_buffer->committing)) { | |
2434 | local_inc(&cpu_buffer->committing); | |
2435 | goto again; | |
2436 | } | |
2437 | } | |
2438 | ||
2439 | static inline void rb_event_discard(struct ring_buffer_event *event) | |
2440 | { | |
2441 | if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) | |
2442 | event = skip_time_extend(event); | |
2443 | ||
2444 | /* array[0] holds the actual length for the discarded event */ | |
2445 | event->array[0] = rb_event_data_length(event) - RB_EVNT_HDR_SIZE; | |
2446 | event->type_len = RINGBUF_TYPE_PADDING; | |
2447 | /* time delta must be non zero */ | |
2448 | if (!event->time_delta) | |
2449 | event->time_delta = 1; | |
2450 | } | |
2451 | ||
babe3fce | 2452 | static __always_inline bool |
d90fd774 SRRH |
2453 | rb_event_is_commit(struct ring_buffer_per_cpu *cpu_buffer, |
2454 | struct ring_buffer_event *event) | |
2455 | { | |
2456 | unsigned long addr = (unsigned long)event; | |
2457 | unsigned long index; | |
2458 | ||
2459 | index = rb_event_index(event); | |
2460 | addr &= PAGE_MASK; | |
2461 | ||
2462 | return cpu_buffer->commit_page->page == (void *)addr && | |
2463 | rb_commit_index(cpu_buffer) == index; | |
2464 | } | |
2465 | ||
babe3fce | 2466 | static __always_inline void |
d90fd774 SRRH |
2467 | rb_update_write_stamp(struct ring_buffer_per_cpu *cpu_buffer, |
2468 | struct ring_buffer_event *event) | |
2469 | { | |
2470 | u64 delta; | |
2471 | ||
2472 | /* | |
2473 | * The event first in the commit queue updates the | |
2474 | * time stamp. | |
2475 | */ | |
2476 | if (rb_event_is_commit(cpu_buffer, event)) { | |
2477 | /* | |
2478 | * A commit event that is first on a page | |
2479 | * updates the write timestamp with the page stamp | |
2480 | */ | |
2481 | if (!rb_event_index(event)) | |
2482 | cpu_buffer->write_stamp = | |
2483 | cpu_buffer->commit_page->page->time_stamp; | |
2484 | else if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) { | |
2485 | delta = event->array[0]; | |
2486 | delta <<= TS_SHIFT; | |
2487 | delta += event->time_delta; | |
2488 | cpu_buffer->write_stamp += delta; | |
2489 | } else | |
2490 | cpu_buffer->write_stamp += event->time_delta; | |
2491 | } | |
2492 | } | |
2493 | ||
2494 | static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, | |
2495 | struct ring_buffer_event *event) | |
2496 | { | |
2497 | local_inc(&cpu_buffer->entries); | |
2498 | rb_update_write_stamp(cpu_buffer, event); | |
2499 | rb_end_commit(cpu_buffer); | |
2500 | } | |
2501 | ||
2502 | static __always_inline void | |
2503 | rb_wakeups(struct ring_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer) | |
2504 | { | |
2505 | bool pagebusy; | |
2506 | ||
2507 | if (buffer->irq_work.waiters_pending) { | |
2508 | buffer->irq_work.waiters_pending = false; | |
2509 | /* irq_work_queue() supplies it's own memory barriers */ | |
2510 | irq_work_queue(&buffer->irq_work.work); | |
2511 | } | |
2512 | ||
2513 | if (cpu_buffer->irq_work.waiters_pending) { | |
2514 | cpu_buffer->irq_work.waiters_pending = false; | |
2515 | /* irq_work_queue() supplies it's own memory barriers */ | |
2516 | irq_work_queue(&cpu_buffer->irq_work.work); | |
2517 | } | |
2518 | ||
2519 | pagebusy = cpu_buffer->reader_page == cpu_buffer->commit_page; | |
2520 | ||
2521 | if (!pagebusy && cpu_buffer->irq_work.full_waiters_pending) { | |
2522 | cpu_buffer->irq_work.wakeup_full = true; | |
2523 | cpu_buffer->irq_work.full_waiters_pending = false; | |
2524 | /* irq_work_queue() supplies it's own memory barriers */ | |
2525 | irq_work_queue(&cpu_buffer->irq_work.work); | |
2526 | } | |
2527 | } | |
2528 | ||
2529 | /* | |
2530 | * The lock and unlock are done within a preempt disable section. | |
2531 | * The current_context per_cpu variable can only be modified | |
2532 | * by the current task between lock and unlock. But it can | |
1a149d7d SRV |
2533 | * be modified more than once via an interrupt. There are four |
2534 | * different contexts that we need to consider. | |
d90fd774 | 2535 | * |
1a149d7d SRV |
2536 | * Normal context. |
2537 | * SoftIRQ context | |
2538 | * IRQ context | |
2539 | * NMI context | |
d90fd774 | 2540 | * |
1a149d7d SRV |
2541 | * If for some reason the ring buffer starts to recurse, we |
2542 | * only allow that to happen at most 4 times (one for each | |
2543 | * context). If it happens 5 times, then we consider this a | |
2544 | * recusive loop and do not let it go further. | |
d90fd774 SRRH |
2545 | */ |
2546 | ||
2547 | static __always_inline int | |
2548 | trace_recursive_lock(struct ring_buffer_per_cpu *cpu_buffer) | |
2549 | { | |
1a149d7d | 2550 | if (cpu_buffer->current_context >= 4) |
d90fd774 SRRH |
2551 | return 1; |
2552 | ||
1a149d7d SRV |
2553 | cpu_buffer->current_context++; |
2554 | /* Interrupts must see this update */ | |
2555 | barrier(); | |
d90fd774 SRRH |
2556 | |
2557 | return 0; | |
2558 | } | |
2559 | ||
2560 | static __always_inline void | |
2561 | trace_recursive_unlock(struct ring_buffer_per_cpu *cpu_buffer) | |
2562 | { | |
1a149d7d SRV |
2563 | /* Don't let the dec leak out */ |
2564 | barrier(); | |
2565 | cpu_buffer->current_context--; | |
d90fd774 SRRH |
2566 | } |
2567 | ||
2568 | /** | |
2569 | * ring_buffer_unlock_commit - commit a reserved | |
2570 | * @buffer: The buffer to commit to | |
2571 | * @event: The event pointer to commit. | |
2572 | * | |
2573 | * This commits the data to the ring buffer, and releases any locks held. | |
2574 | * | |
2575 | * Must be paired with ring_buffer_lock_reserve. | |
2576 | */ | |
2577 | int ring_buffer_unlock_commit(struct ring_buffer *buffer, | |
2578 | struct ring_buffer_event *event) | |
2579 | { | |
2580 | struct ring_buffer_per_cpu *cpu_buffer; | |
2581 | int cpu = raw_smp_processor_id(); | |
2582 | ||
2583 | cpu_buffer = buffer->buffers[cpu]; | |
2584 | ||
2585 | rb_commit(cpu_buffer, event); | |
2586 | ||
2587 | rb_wakeups(buffer, cpu_buffer); | |
2588 | ||
2589 | trace_recursive_unlock(cpu_buffer); | |
2590 | ||
2591 | preempt_enable_notrace(); | |
2592 | ||
2593 | return 0; | |
2594 | } | |
2595 | EXPORT_SYMBOL_GPL(ring_buffer_unlock_commit); | |
2596 | ||
2597 | static noinline void | |
2598 | rb_handle_timestamp(struct ring_buffer_per_cpu *cpu_buffer, | |
d90fd774 SRRH |
2599 | struct rb_event_info *info) |
2600 | { | |
d90fd774 SRRH |
2601 | WARN_ONCE(info->delta > (1ULL << 59), |
2602 | KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n%s", | |
2603 | (unsigned long long)info->delta, | |
2604 | (unsigned long long)info->ts, | |
2605 | (unsigned long long)cpu_buffer->write_stamp, | |
2606 | sched_clock_stable() ? "" : | |
2607 | "If you just came from a suspend/resume,\n" | |
2608 | "please switch to the trace global clock:\n" | |
2609 | " echo global > /sys/kernel/debug/tracing/trace_clock\n"); | |
b7dc42fd | 2610 | info->add_timestamp = 1; |
9826b273 SRRH |
2611 | } |
2612 | ||
6634ff26 SR |
2613 | static struct ring_buffer_event * |
2614 | __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, | |
fcc742ea | 2615 | struct rb_event_info *info) |
6634ff26 | 2616 | { |
6634ff26 | 2617 | struct ring_buffer_event *event; |
fcc742ea | 2618 | struct buffer_page *tail_page; |
6634ff26 | 2619 | unsigned long tail, write; |
b7dc42fd SRRH |
2620 | |
2621 | /* | |
2622 | * If the time delta since the last event is too big to | |
2623 | * hold in the time field of the event, then we append a | |
2624 | * TIME EXTEND event ahead of the data event. | |
2625 | */ | |
2626 | if (unlikely(info->add_timestamp)) | |
2627 | info->length += RB_LEN_TIME_EXTEND; | |
69d1b839 | 2628 | |
8573636e SRRH |
2629 | /* Don't let the compiler play games with cpu_buffer->tail_page */ |
2630 | tail_page = info->tail_page = READ_ONCE(cpu_buffer->tail_page); | |
fcc742ea | 2631 | write = local_add_return(info->length, &tail_page->write); |
77ae365e SR |
2632 | |
2633 | /* set write to only the index of the write */ | |
2634 | write &= RB_WRITE_MASK; | |
fcc742ea | 2635 | tail = write - info->length; |
6634ff26 | 2636 | |
6634ff26 | 2637 | /* |
a4543a2f | 2638 | * If this is the first commit on the page, then it has the same |
b7dc42fd | 2639 | * timestamp as the page itself. |
6634ff26 | 2640 | */ |
b7dc42fd | 2641 | if (!tail) |
a4543a2f SRRH |
2642 | info->delta = 0; |
2643 | ||
b7dc42fd SRRH |
2644 | /* See if we shot pass the end of this buffer page */ |
2645 | if (unlikely(write > BUF_PAGE_SIZE)) | |
2646 | return rb_move_tail(cpu_buffer, tail, info); | |
a4543a2f | 2647 | |
b7dc42fd SRRH |
2648 | /* We reserved something on the buffer */ |
2649 | ||
2650 | event = __rb_page_index(tail_page, tail); | |
a4543a2f SRRH |
2651 | rb_update_event(cpu_buffer, event, info); |
2652 | ||
2653 | local_inc(&tail_page->entries); | |
6634ff26 | 2654 | |
b7dc42fd SRRH |
2655 | /* |
2656 | * If this is the first commit on the page, then update | |
2657 | * its timestamp. | |
2658 | */ | |
2659 | if (!tail) | |
2660 | tail_page->page->time_stamp = info->ts; | |
2661 | ||
c64e148a | 2662 | /* account for these added bytes */ |
fcc742ea | 2663 | local_add(info->length, &cpu_buffer->entries_bytes); |
c64e148a | 2664 | |
6634ff26 SR |
2665 | return event; |
2666 | } | |
2667 | ||
fa7ffb39 | 2668 | static __always_inline struct ring_buffer_event * |
62f0b3eb SR |
2669 | rb_reserve_next_event(struct ring_buffer *buffer, |
2670 | struct ring_buffer_per_cpu *cpu_buffer, | |
1cd8d735 | 2671 | unsigned long length) |
7a8e76a3 SR |
2672 | { |
2673 | struct ring_buffer_event *event; | |
fcc742ea | 2674 | struct rb_event_info info; |
818e3dd3 | 2675 | int nr_loops = 0; |
b7dc42fd | 2676 | u64 diff; |
7a8e76a3 | 2677 | |
fa743953 SR |
2678 | rb_start_commit(cpu_buffer); |
2679 | ||
85bac32c | 2680 | #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP |
62f0b3eb SR |
2681 | /* |
2682 | * Due to the ability to swap a cpu buffer from a buffer | |
2683 | * it is possible it was swapped before we committed. | |
2684 | * (committing stops a swap). We check for it here and | |
2685 | * if it happened, we have to fail the write. | |
2686 | */ | |
2687 | barrier(); | |
6aa7de05 | 2688 | if (unlikely(READ_ONCE(cpu_buffer->buffer) != buffer)) { |
62f0b3eb SR |
2689 | local_dec(&cpu_buffer->committing); |
2690 | local_dec(&cpu_buffer->commits); | |
2691 | return NULL; | |
2692 | } | |
85bac32c | 2693 | #endif |
b7dc42fd | 2694 | |
fcc742ea | 2695 | info.length = rb_calculate_event_length(length); |
a4543a2f | 2696 | again: |
b7dc42fd SRRH |
2697 | info.add_timestamp = 0; |
2698 | info.delta = 0; | |
2699 | ||
818e3dd3 SR |
2700 | /* |
2701 | * We allow for interrupts to reenter here and do a trace. | |
2702 | * If one does, it will cause this original code to loop | |
2703 | * back here. Even with heavy interrupts happening, this | |
2704 | * should only happen a few times in a row. If this happens | |
2705 | * 1000 times in a row, there must be either an interrupt | |
2706 | * storm or we have something buggy. | |
2707 | * Bail! | |
2708 | */ | |
3e89c7bb | 2709 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000)) |
fa743953 | 2710 | goto out_fail; |
818e3dd3 | 2711 | |
b7dc42fd SRRH |
2712 | info.ts = rb_time_stamp(cpu_buffer->buffer); |
2713 | diff = info.ts - cpu_buffer->write_stamp; | |
2714 | ||
2715 | /* make sure this diff is calculated here */ | |
2716 | barrier(); | |
2717 | ||
2718 | /* Did the write stamp get updated already? */ | |
2719 | if (likely(info.ts >= cpu_buffer->write_stamp)) { | |
2720 | info.delta = diff; | |
2721 | if (unlikely(test_time_stamp(info.delta))) | |
2722 | rb_handle_timestamp(cpu_buffer, &info); | |
2723 | } | |
2724 | ||
fcc742ea SRRH |
2725 | event = __rb_reserve_next(cpu_buffer, &info); |
2726 | ||
bd1b7cd3 SRRH |
2727 | if (unlikely(PTR_ERR(event) == -EAGAIN)) { |
2728 | if (info.add_timestamp) | |
2729 | info.length -= RB_LEN_TIME_EXTEND; | |
bf41a158 | 2730 | goto again; |
bd1b7cd3 | 2731 | } |
bf41a158 | 2732 | |
fa743953 SR |
2733 | if (!event) |
2734 | goto out_fail; | |
7a8e76a3 | 2735 | |
7a8e76a3 | 2736 | return event; |
fa743953 SR |
2737 | |
2738 | out_fail: | |
2739 | rb_end_commit(cpu_buffer); | |
2740 | return NULL; | |
7a8e76a3 SR |
2741 | } |
2742 | ||
2743 | /** | |
2744 | * ring_buffer_lock_reserve - reserve a part of the buffer | |
2745 | * @buffer: the ring buffer to reserve from | |
2746 | * @length: the length of the data to reserve (excluding event header) | |
7a8e76a3 SR |
2747 | * |
2748 | * Returns a reseverd event on the ring buffer to copy directly to. | |
2749 | * The user of this interface will need to get the body to write into | |
2750 | * and can use the ring_buffer_event_data() interface. | |
2751 | * | |
2752 | * The length is the length of the data needed, not the event length | |
2753 | * which also includes the event header. | |
2754 | * | |
2755 | * Must be paired with ring_buffer_unlock_commit, unless NULL is returned. | |
2756 | * If NULL is returned, then nothing has been allocated or locked. | |
2757 | */ | |
2758 | struct ring_buffer_event * | |
0a987751 | 2759 | ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length) |
7a8e76a3 SR |
2760 | { |
2761 | struct ring_buffer_per_cpu *cpu_buffer; | |
2762 | struct ring_buffer_event *event; | |
5168ae50 | 2763 | int cpu; |
7a8e76a3 | 2764 | |
bf41a158 | 2765 | /* If we are tracing schedule, we don't want to recurse */ |
5168ae50 | 2766 | preempt_disable_notrace(); |
bf41a158 | 2767 | |
3205f806 | 2768 | if (unlikely(atomic_read(&buffer->record_disabled))) |
58a09ec6 | 2769 | goto out; |
261842b7 | 2770 | |
7a8e76a3 SR |
2771 | cpu = raw_smp_processor_id(); |
2772 | ||
3205f806 | 2773 | if (unlikely(!cpumask_test_cpu(cpu, buffer->cpumask))) |
d769041f | 2774 | goto out; |
7a8e76a3 SR |
2775 | |
2776 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 | 2777 | |
3205f806 | 2778 | if (unlikely(atomic_read(&cpu_buffer->record_disabled))) |
d769041f | 2779 | goto out; |
7a8e76a3 | 2780 | |
3205f806 | 2781 | if (unlikely(length > BUF_MAX_DATA_SIZE)) |
bf41a158 | 2782 | goto out; |
7a8e76a3 | 2783 | |
58a09ec6 SRRH |
2784 | if (unlikely(trace_recursive_lock(cpu_buffer))) |
2785 | goto out; | |
2786 | ||
62f0b3eb | 2787 | event = rb_reserve_next_event(buffer, cpu_buffer, length); |
7a8e76a3 | 2788 | if (!event) |
58a09ec6 | 2789 | goto out_unlock; |
7a8e76a3 SR |
2790 | |
2791 | return event; | |
2792 | ||
58a09ec6 SRRH |
2793 | out_unlock: |
2794 | trace_recursive_unlock(cpu_buffer); | |
d769041f | 2795 | out: |
5168ae50 | 2796 | preempt_enable_notrace(); |
7a8e76a3 SR |
2797 | return NULL; |
2798 | } | |
c4f50183 | 2799 | EXPORT_SYMBOL_GPL(ring_buffer_lock_reserve); |
7a8e76a3 | 2800 | |
a1863c21 SR |
2801 | /* |
2802 | * Decrement the entries to the page that an event is on. | |
2803 | * The event does not even need to exist, only the pointer | |
2804 | * to the page it is on. This may only be called before the commit | |
2805 | * takes place. | |
2806 | */ | |
2807 | static inline void | |
2808 | rb_decrement_entry(struct ring_buffer_per_cpu *cpu_buffer, | |
2809 | struct ring_buffer_event *event) | |
2810 | { | |
2811 | unsigned long addr = (unsigned long)event; | |
2812 | struct buffer_page *bpage = cpu_buffer->commit_page; | |
2813 | struct buffer_page *start; | |
2814 | ||
2815 | addr &= PAGE_MASK; | |
2816 | ||
2817 | /* Do the likely case first */ | |
2818 | if (likely(bpage->page == (void *)addr)) { | |
2819 | local_dec(&bpage->entries); | |
2820 | return; | |
2821 | } | |
2822 | ||
2823 | /* | |
2824 | * Because the commit page may be on the reader page we | |
2825 | * start with the next page and check the end loop there. | |
2826 | */ | |
2827 | rb_inc_page(cpu_buffer, &bpage); | |
2828 | start = bpage; | |
2829 | do { | |
2830 | if (bpage->page == (void *)addr) { | |
2831 | local_dec(&bpage->entries); | |
2832 | return; | |
2833 | } | |
2834 | rb_inc_page(cpu_buffer, &bpage); | |
2835 | } while (bpage != start); | |
2836 | ||
2837 | /* commit not part of this buffer?? */ | |
2838 | RB_WARN_ON(cpu_buffer, 1); | |
2839 | } | |
2840 | ||
fa1b47dd SR |
2841 | /** |
2842 | * ring_buffer_commit_discard - discard an event that has not been committed | |
2843 | * @buffer: the ring buffer | |
2844 | * @event: non committed event to discard | |
2845 | * | |
dc892f73 SR |
2846 | * Sometimes an event that is in the ring buffer needs to be ignored. |
2847 | * This function lets the user discard an event in the ring buffer | |
2848 | * and then that event will not be read later. | |
2849 | * | |
2850 | * This function only works if it is called before the the item has been | |
2851 | * committed. It will try to free the event from the ring buffer | |
fa1b47dd SR |
2852 | * if another event has not been added behind it. |
2853 | * | |
2854 | * If another event has been added behind it, it will set the event | |
2855 | * up as discarded, and perform the commit. | |
2856 | * | |
2857 | * If this function is called, do not call ring_buffer_unlock_commit on | |
2858 | * the event. | |
2859 | */ | |
2860 | void ring_buffer_discard_commit(struct ring_buffer *buffer, | |
2861 | struct ring_buffer_event *event) | |
2862 | { | |
2863 | struct ring_buffer_per_cpu *cpu_buffer; | |
fa1b47dd SR |
2864 | int cpu; |
2865 | ||
2866 | /* The event is discarded regardless */ | |
f3b9aae1 | 2867 | rb_event_discard(event); |
fa1b47dd | 2868 | |
fa743953 SR |
2869 | cpu = smp_processor_id(); |
2870 | cpu_buffer = buffer->buffers[cpu]; | |
2871 | ||
fa1b47dd SR |
2872 | /* |
2873 | * This must only be called if the event has not been | |
2874 | * committed yet. Thus we can assume that preemption | |
2875 | * is still disabled. | |
2876 | */ | |
fa743953 | 2877 | RB_WARN_ON(buffer, !local_read(&cpu_buffer->committing)); |
fa1b47dd | 2878 | |
a1863c21 | 2879 | rb_decrement_entry(cpu_buffer, event); |
0f2541d2 | 2880 | if (rb_try_to_discard(cpu_buffer, event)) |
edd813bf | 2881 | goto out; |
fa1b47dd SR |
2882 | |
2883 | /* | |
2884 | * The commit is still visible by the reader, so we | |
a1863c21 | 2885 | * must still update the timestamp. |
fa1b47dd | 2886 | */ |
a1863c21 | 2887 | rb_update_write_stamp(cpu_buffer, event); |
fa1b47dd | 2888 | out: |
fa743953 | 2889 | rb_end_commit(cpu_buffer); |
fa1b47dd | 2890 | |
58a09ec6 | 2891 | trace_recursive_unlock(cpu_buffer); |
f3b9aae1 | 2892 | |
5168ae50 | 2893 | preempt_enable_notrace(); |
fa1b47dd SR |
2894 | |
2895 | } | |
2896 | EXPORT_SYMBOL_GPL(ring_buffer_discard_commit); | |
2897 | ||
7a8e76a3 SR |
2898 | /** |
2899 | * ring_buffer_write - write data to the buffer without reserving | |
2900 | * @buffer: The ring buffer to write to. | |
2901 | * @length: The length of the data being written (excluding the event header) | |
2902 | * @data: The data to write to the buffer. | |
2903 | * | |
2904 | * This is like ring_buffer_lock_reserve and ring_buffer_unlock_commit as | |
2905 | * one function. If you already have the data to write to the buffer, it | |
2906 | * may be easier to simply call this function. | |
2907 | * | |
2908 | * Note, like ring_buffer_lock_reserve, the length is the length of the data | |
2909 | * and not the length of the event which would hold the header. | |
2910 | */ | |
2911 | int ring_buffer_write(struct ring_buffer *buffer, | |
01e3e710 DS |
2912 | unsigned long length, |
2913 | void *data) | |
7a8e76a3 SR |
2914 | { |
2915 | struct ring_buffer_per_cpu *cpu_buffer; | |
2916 | struct ring_buffer_event *event; | |
7a8e76a3 SR |
2917 | void *body; |
2918 | int ret = -EBUSY; | |
5168ae50 | 2919 | int cpu; |
7a8e76a3 | 2920 | |
5168ae50 | 2921 | preempt_disable_notrace(); |
bf41a158 | 2922 | |
52fbe9cd LJ |
2923 | if (atomic_read(&buffer->record_disabled)) |
2924 | goto out; | |
2925 | ||
7a8e76a3 SR |
2926 | cpu = raw_smp_processor_id(); |
2927 | ||
9e01c1b7 | 2928 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
d769041f | 2929 | goto out; |
7a8e76a3 SR |
2930 | |
2931 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 SR |
2932 | |
2933 | if (atomic_read(&cpu_buffer->record_disabled)) | |
2934 | goto out; | |
2935 | ||
be957c44 SR |
2936 | if (length > BUF_MAX_DATA_SIZE) |
2937 | goto out; | |
2938 | ||
985e871b SRRH |
2939 | if (unlikely(trace_recursive_lock(cpu_buffer))) |
2940 | goto out; | |
2941 | ||
62f0b3eb | 2942 | event = rb_reserve_next_event(buffer, cpu_buffer, length); |
7a8e76a3 | 2943 | if (!event) |
985e871b | 2944 | goto out_unlock; |
7a8e76a3 SR |
2945 | |
2946 | body = rb_event_data(event); | |
2947 | ||
2948 | memcpy(body, data, length); | |
2949 | ||
2950 | rb_commit(cpu_buffer, event); | |
2951 | ||
15693458 SRRH |
2952 | rb_wakeups(buffer, cpu_buffer); |
2953 | ||
7a8e76a3 | 2954 | ret = 0; |
985e871b SRRH |
2955 | |
2956 | out_unlock: | |
2957 | trace_recursive_unlock(cpu_buffer); | |
2958 | ||
7a8e76a3 | 2959 | out: |
5168ae50 | 2960 | preempt_enable_notrace(); |
7a8e76a3 SR |
2961 | |
2962 | return ret; | |
2963 | } | |
c4f50183 | 2964 | EXPORT_SYMBOL_GPL(ring_buffer_write); |
7a8e76a3 | 2965 | |
da58834c | 2966 | static bool rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) |
bf41a158 SR |
2967 | { |
2968 | struct buffer_page *reader = cpu_buffer->reader_page; | |
77ae365e | 2969 | struct buffer_page *head = rb_set_head_page(cpu_buffer); |
bf41a158 SR |
2970 | struct buffer_page *commit = cpu_buffer->commit_page; |
2971 | ||
77ae365e SR |
2972 | /* In case of error, head will be NULL */ |
2973 | if (unlikely(!head)) | |
da58834c | 2974 | return true; |
77ae365e | 2975 | |
bf41a158 SR |
2976 | return reader->read == rb_page_commit(reader) && |
2977 | (commit == reader || | |
2978 | (commit == head && | |
2979 | head->read == rb_page_commit(commit))); | |
2980 | } | |
2981 | ||
7a8e76a3 SR |
2982 | /** |
2983 | * ring_buffer_record_disable - stop all writes into the buffer | |
2984 | * @buffer: The ring buffer to stop writes to. | |
2985 | * | |
2986 | * This prevents all writes to the buffer. Any attempt to write | |
2987 | * to the buffer after this will fail and return NULL. | |
2988 | * | |
2989 | * The caller should call synchronize_sched() after this. | |
2990 | */ | |
2991 | void ring_buffer_record_disable(struct ring_buffer *buffer) | |
2992 | { | |
2993 | atomic_inc(&buffer->record_disabled); | |
2994 | } | |
c4f50183 | 2995 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable); |
7a8e76a3 SR |
2996 | |
2997 | /** | |
2998 | * ring_buffer_record_enable - enable writes to the buffer | |
2999 | * @buffer: The ring buffer to enable writes | |
3000 | * | |
3001 | * Note, multiple disables will need the same number of enables | |
c41b20e7 | 3002 | * to truly enable the writing (much like preempt_disable). |
7a8e76a3 SR |
3003 | */ |
3004 | void ring_buffer_record_enable(struct ring_buffer *buffer) | |
3005 | { | |
3006 | atomic_dec(&buffer->record_disabled); | |
3007 | } | |
c4f50183 | 3008 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable); |
7a8e76a3 | 3009 | |
499e5470 SR |
3010 | /** |
3011 | * ring_buffer_record_off - stop all writes into the buffer | |
3012 | * @buffer: The ring buffer to stop writes to. | |
3013 | * | |
3014 | * This prevents all writes to the buffer. Any attempt to write | |
3015 | * to the buffer after this will fail and return NULL. | |
3016 | * | |
3017 | * This is different than ring_buffer_record_disable() as | |
87abb3b1 | 3018 | * it works like an on/off switch, where as the disable() version |
499e5470 SR |
3019 | * must be paired with a enable(). |
3020 | */ | |
3021 | void ring_buffer_record_off(struct ring_buffer *buffer) | |
3022 | { | |
3023 | unsigned int rd; | |
3024 | unsigned int new_rd; | |
3025 | ||
3026 | do { | |
3027 | rd = atomic_read(&buffer->record_disabled); | |
3028 | new_rd = rd | RB_BUFFER_OFF; | |
3029 | } while (atomic_cmpxchg(&buffer->record_disabled, rd, new_rd) != rd); | |
3030 | } | |
3031 | EXPORT_SYMBOL_GPL(ring_buffer_record_off); | |
3032 | ||
3033 | /** | |
3034 | * ring_buffer_record_on - restart writes into the buffer | |
3035 | * @buffer: The ring buffer to start writes to. | |
3036 | * | |
3037 | * This enables all writes to the buffer that was disabled by | |
3038 | * ring_buffer_record_off(). | |
3039 | * | |
3040 | * This is different than ring_buffer_record_enable() as | |
87abb3b1 | 3041 | * it works like an on/off switch, where as the enable() version |
499e5470 SR |
3042 | * must be paired with a disable(). |
3043 | */ | |
3044 | void ring_buffer_record_on(struct ring_buffer *buffer) | |
3045 | { | |
3046 | unsigned int rd; | |
3047 | unsigned int new_rd; | |
3048 | ||
3049 | do { | |
3050 | rd = atomic_read(&buffer->record_disabled); | |
3051 | new_rd = rd & ~RB_BUFFER_OFF; | |
3052 | } while (atomic_cmpxchg(&buffer->record_disabled, rd, new_rd) != rd); | |
3053 | } | |
3054 | EXPORT_SYMBOL_GPL(ring_buffer_record_on); | |
3055 | ||
3056 | /** | |
3057 | * ring_buffer_record_is_on - return true if the ring buffer can write | |
3058 | * @buffer: The ring buffer to see if write is enabled | |
3059 | * | |
3060 | * Returns true if the ring buffer is in a state that it accepts writes. | |
3061 | */ | |
3062 | int ring_buffer_record_is_on(struct ring_buffer *buffer) | |
3063 | { | |
3064 | return !atomic_read(&buffer->record_disabled); | |
3065 | } | |
3066 | ||
7a8e76a3 SR |
3067 | /** |
3068 | * ring_buffer_record_disable_cpu - stop all writes into the cpu_buffer | |
3069 | * @buffer: The ring buffer to stop writes to. | |
3070 | * @cpu: The CPU buffer to stop | |
3071 | * | |
3072 | * This prevents all writes to the buffer. Any attempt to write | |
3073 | * to the buffer after this will fail and return NULL. | |
3074 | * | |
3075 | * The caller should call synchronize_sched() after this. | |
3076 | */ | |
3077 | void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu) | |
3078 | { | |
3079 | struct ring_buffer_per_cpu *cpu_buffer; | |
3080 | ||
9e01c1b7 | 3081 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 3082 | return; |
7a8e76a3 SR |
3083 | |
3084 | cpu_buffer = buffer->buffers[cpu]; | |
3085 | atomic_inc(&cpu_buffer->record_disabled); | |
3086 | } | |
c4f50183 | 3087 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable_cpu); |
7a8e76a3 SR |
3088 | |
3089 | /** | |
3090 | * ring_buffer_record_enable_cpu - enable writes to the buffer | |
3091 | * @buffer: The ring buffer to enable writes | |
3092 | * @cpu: The CPU to enable. | |
3093 | * | |
3094 | * Note, multiple disables will need the same number of enables | |
c41b20e7 | 3095 | * to truly enable the writing (much like preempt_disable). |
7a8e76a3 SR |
3096 | */ |
3097 | void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu) | |
3098 | { | |
3099 | struct ring_buffer_per_cpu *cpu_buffer; | |
3100 | ||
9e01c1b7 | 3101 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 3102 | return; |
7a8e76a3 SR |
3103 | |
3104 | cpu_buffer = buffer->buffers[cpu]; | |
3105 | atomic_dec(&cpu_buffer->record_disabled); | |
3106 | } | |
c4f50183 | 3107 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu); |
7a8e76a3 | 3108 | |
f6195aa0 SR |
3109 | /* |
3110 | * The total entries in the ring buffer is the running counter | |
3111 | * of entries entered into the ring buffer, minus the sum of | |
3112 | * the entries read from the ring buffer and the number of | |
3113 | * entries that were overwritten. | |
3114 | */ | |
3115 | static inline unsigned long | |
3116 | rb_num_of_entries(struct ring_buffer_per_cpu *cpu_buffer) | |
3117 | { | |
3118 | return local_read(&cpu_buffer->entries) - | |
3119 | (local_read(&cpu_buffer->overrun) + cpu_buffer->read); | |
3120 | } | |
3121 | ||
c64e148a VN |
3122 | /** |
3123 | * ring_buffer_oldest_event_ts - get the oldest event timestamp from the buffer | |
3124 | * @buffer: The ring buffer | |
3125 | * @cpu: The per CPU buffer to read from. | |
3126 | */ | |
50ecf2c3 | 3127 | u64 ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu) |
c64e148a VN |
3128 | { |
3129 | unsigned long flags; | |
3130 | struct ring_buffer_per_cpu *cpu_buffer; | |
3131 | struct buffer_page *bpage; | |
da830e58 | 3132 | u64 ret = 0; |
c64e148a VN |
3133 | |
3134 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
3135 | return 0; | |
3136 | ||
3137 | cpu_buffer = buffer->buffers[cpu]; | |
7115e3fc | 3138 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
c64e148a VN |
3139 | /* |
3140 | * if the tail is on reader_page, oldest time stamp is on the reader | |
3141 | * page | |
3142 | */ | |
3143 | if (cpu_buffer->tail_page == cpu_buffer->reader_page) | |
3144 | bpage = cpu_buffer->reader_page; | |
3145 | else | |
3146 | bpage = rb_set_head_page(cpu_buffer); | |
54f7be5b SR |
3147 | if (bpage) |
3148 | ret = bpage->page->time_stamp; | |
7115e3fc | 3149 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
c64e148a VN |
3150 | |
3151 | return ret; | |
3152 | } | |
3153 | EXPORT_SYMBOL_GPL(ring_buffer_oldest_event_ts); | |
3154 | ||
3155 | /** | |
3156 | * ring_buffer_bytes_cpu - get the number of bytes consumed in a cpu buffer | |
3157 | * @buffer: The ring buffer | |
3158 | * @cpu: The per CPU buffer to read from. | |
3159 | */ | |
3160 | unsigned long ring_buffer_bytes_cpu(struct ring_buffer *buffer, int cpu) | |
3161 | { | |
3162 | struct ring_buffer_per_cpu *cpu_buffer; | |
3163 | unsigned long ret; | |
3164 | ||
3165 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
3166 | return 0; | |
3167 | ||
3168 | cpu_buffer = buffer->buffers[cpu]; | |
3169 | ret = local_read(&cpu_buffer->entries_bytes) - cpu_buffer->read_bytes; | |
3170 | ||
3171 | return ret; | |
3172 | } | |
3173 | EXPORT_SYMBOL_GPL(ring_buffer_bytes_cpu); | |
3174 | ||
7a8e76a3 SR |
3175 | /** |
3176 | * ring_buffer_entries_cpu - get the number of entries in a cpu buffer | |
3177 | * @buffer: The ring buffer | |
3178 | * @cpu: The per CPU buffer to get the entries from. | |
3179 | */ | |
3180 | unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu) | |
3181 | { | |
3182 | struct ring_buffer_per_cpu *cpu_buffer; | |
3183 | ||
9e01c1b7 | 3184 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 3185 | return 0; |
7a8e76a3 SR |
3186 | |
3187 | cpu_buffer = buffer->buffers[cpu]; | |
554f786e | 3188 | |
f6195aa0 | 3189 | return rb_num_of_entries(cpu_buffer); |
7a8e76a3 | 3190 | } |
c4f50183 | 3191 | EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu); |
7a8e76a3 SR |
3192 | |
3193 | /** | |
884bfe89 SP |
3194 | * ring_buffer_overrun_cpu - get the number of overruns caused by the ring |
3195 | * buffer wrapping around (only if RB_FL_OVERWRITE is on). | |
7a8e76a3 SR |
3196 | * @buffer: The ring buffer |
3197 | * @cpu: The per CPU buffer to get the number of overruns from | |
3198 | */ | |
3199 | unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu) | |
3200 | { | |
3201 | struct ring_buffer_per_cpu *cpu_buffer; | |
8aabee57 | 3202 | unsigned long ret; |
7a8e76a3 | 3203 | |
9e01c1b7 | 3204 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 3205 | return 0; |
7a8e76a3 SR |
3206 | |
3207 | cpu_buffer = buffer->buffers[cpu]; | |
77ae365e | 3208 | ret = local_read(&cpu_buffer->overrun); |
554f786e SR |
3209 | |
3210 | return ret; | |
7a8e76a3 | 3211 | } |
c4f50183 | 3212 | EXPORT_SYMBOL_GPL(ring_buffer_overrun_cpu); |
7a8e76a3 | 3213 | |
f0d2c681 | 3214 | /** |
884bfe89 SP |
3215 | * ring_buffer_commit_overrun_cpu - get the number of overruns caused by |
3216 | * commits failing due to the buffer wrapping around while there are uncommitted | |
3217 | * events, such as during an interrupt storm. | |
f0d2c681 SR |
3218 | * @buffer: The ring buffer |
3219 | * @cpu: The per CPU buffer to get the number of overruns from | |
3220 | */ | |
3221 | unsigned long | |
3222 | ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu) | |
3223 | { | |
3224 | struct ring_buffer_per_cpu *cpu_buffer; | |
3225 | unsigned long ret; | |
3226 | ||
3227 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
3228 | return 0; | |
3229 | ||
3230 | cpu_buffer = buffer->buffers[cpu]; | |
77ae365e | 3231 | ret = local_read(&cpu_buffer->commit_overrun); |
f0d2c681 SR |
3232 | |
3233 | return ret; | |
3234 | } | |
3235 | EXPORT_SYMBOL_GPL(ring_buffer_commit_overrun_cpu); | |
3236 | ||
884bfe89 SP |
3237 | /** |
3238 | * ring_buffer_dropped_events_cpu - get the number of dropped events caused by | |
3239 | * the ring buffer filling up (only if RB_FL_OVERWRITE is off). | |
3240 | * @buffer: The ring buffer | |
3241 | * @cpu: The per CPU buffer to get the number of overruns from | |
3242 | */ | |
3243 | unsigned long | |
3244 | ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu) | |
3245 | { | |
3246 | struct ring_buffer_per_cpu *cpu_buffer; | |
3247 | unsigned long ret; | |
3248 | ||
3249 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
3250 | return 0; | |
3251 | ||
3252 | cpu_buffer = buffer->buffers[cpu]; | |
3253 | ret = local_read(&cpu_buffer->dropped_events); | |
3254 | ||
3255 | return ret; | |
3256 | } | |
3257 | EXPORT_SYMBOL_GPL(ring_buffer_dropped_events_cpu); | |
3258 | ||
ad964704 SRRH |
3259 | /** |
3260 | * ring_buffer_read_events_cpu - get the number of events successfully read | |
3261 | * @buffer: The ring buffer | |
3262 | * @cpu: The per CPU buffer to get the number of events read | |
3263 | */ | |
3264 | unsigned long | |
3265 | ring_buffer_read_events_cpu(struct ring_buffer *buffer, int cpu) | |
3266 | { | |
3267 | struct ring_buffer_per_cpu *cpu_buffer; | |
3268 | ||
3269 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
3270 | return 0; | |
3271 | ||
3272 | cpu_buffer = buffer->buffers[cpu]; | |
3273 | return cpu_buffer->read; | |
3274 | } | |
3275 | EXPORT_SYMBOL_GPL(ring_buffer_read_events_cpu); | |
3276 | ||
7a8e76a3 SR |
3277 | /** |
3278 | * ring_buffer_entries - get the number of entries in a buffer | |
3279 | * @buffer: The ring buffer | |
3280 | * | |
3281 | * Returns the total number of entries in the ring buffer | |
3282 | * (all CPU entries) | |
3283 | */ | |
3284 | unsigned long ring_buffer_entries(struct ring_buffer *buffer) | |
3285 | { | |
3286 | struct ring_buffer_per_cpu *cpu_buffer; | |
3287 | unsigned long entries = 0; | |
3288 | int cpu; | |
3289 | ||
3290 | /* if you care about this being correct, lock the buffer */ | |
3291 | for_each_buffer_cpu(buffer, cpu) { | |
3292 | cpu_buffer = buffer->buffers[cpu]; | |
f6195aa0 | 3293 | entries += rb_num_of_entries(cpu_buffer); |
7a8e76a3 SR |
3294 | } |
3295 | ||
3296 | return entries; | |
3297 | } | |
c4f50183 | 3298 | EXPORT_SYMBOL_GPL(ring_buffer_entries); |
7a8e76a3 SR |
3299 | |
3300 | /** | |
67b394f7 | 3301 | * ring_buffer_overruns - get the number of overruns in buffer |
7a8e76a3 SR |
3302 | * @buffer: The ring buffer |
3303 | * | |
3304 | * Returns the total number of overruns in the ring buffer | |
3305 | * (all CPU entries) | |
3306 | */ | |
3307 | unsigned long ring_buffer_overruns(struct ring_buffer *buffer) | |
3308 | { | |
3309 | struct ring_buffer_per_cpu *cpu_buffer; | |
3310 | unsigned long overruns = 0; | |
3311 | int cpu; | |
3312 | ||
3313 | /* if you care about this being correct, lock the buffer */ | |
3314 | for_each_buffer_cpu(buffer, cpu) { | |
3315 | cpu_buffer = buffer->buffers[cpu]; | |
77ae365e | 3316 | overruns += local_read(&cpu_buffer->overrun); |
7a8e76a3 SR |
3317 | } |
3318 | ||
3319 | return overruns; | |
3320 | } | |
c4f50183 | 3321 | EXPORT_SYMBOL_GPL(ring_buffer_overruns); |
7a8e76a3 | 3322 | |
642edba5 | 3323 | static void rb_iter_reset(struct ring_buffer_iter *iter) |
7a8e76a3 SR |
3324 | { |
3325 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
3326 | ||
d769041f | 3327 | /* Iterator usage is expected to have record disabled */ |
651e22f2 SRRH |
3328 | iter->head_page = cpu_buffer->reader_page; |
3329 | iter->head = cpu_buffer->reader_page->read; | |
3330 | ||
3331 | iter->cache_reader_page = iter->head_page; | |
24607f11 | 3332 | iter->cache_read = cpu_buffer->read; |
651e22f2 | 3333 | |
d769041f SR |
3334 | if (iter->head) |
3335 | iter->read_stamp = cpu_buffer->read_stamp; | |
3336 | else | |
abc9b56d | 3337 | iter->read_stamp = iter->head_page->page->time_stamp; |
642edba5 | 3338 | } |
f83c9d0f | 3339 | |
642edba5 SR |
3340 | /** |
3341 | * ring_buffer_iter_reset - reset an iterator | |
3342 | * @iter: The iterator to reset | |
3343 | * | |
3344 | * Resets the iterator, so that it will start from the beginning | |
3345 | * again. | |
3346 | */ | |
3347 | void ring_buffer_iter_reset(struct ring_buffer_iter *iter) | |
3348 | { | |
554f786e | 3349 | struct ring_buffer_per_cpu *cpu_buffer; |
642edba5 SR |
3350 | unsigned long flags; |
3351 | ||
554f786e SR |
3352 | if (!iter) |
3353 | return; | |
3354 | ||
3355 | cpu_buffer = iter->cpu_buffer; | |
3356 | ||
5389f6fa | 3357 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
642edba5 | 3358 | rb_iter_reset(iter); |
5389f6fa | 3359 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
7a8e76a3 | 3360 | } |
c4f50183 | 3361 | EXPORT_SYMBOL_GPL(ring_buffer_iter_reset); |
7a8e76a3 SR |
3362 | |
3363 | /** | |
3364 | * ring_buffer_iter_empty - check if an iterator has no more to read | |
3365 | * @iter: The iterator to check | |
3366 | */ | |
3367 | int ring_buffer_iter_empty(struct ring_buffer_iter *iter) | |
3368 | { | |
3369 | struct ring_buffer_per_cpu *cpu_buffer; | |
78f7a45d SRV |
3370 | struct buffer_page *reader; |
3371 | struct buffer_page *head_page; | |
3372 | struct buffer_page *commit_page; | |
3373 | unsigned commit; | |
7a8e76a3 SR |
3374 | |
3375 | cpu_buffer = iter->cpu_buffer; | |
3376 | ||
78f7a45d SRV |
3377 | /* Remember, trace recording is off when iterator is in use */ |
3378 | reader = cpu_buffer->reader_page; | |
3379 | head_page = cpu_buffer->head_page; | |
3380 | commit_page = cpu_buffer->commit_page; | |
3381 | commit = rb_page_commit(commit_page); | |
3382 | ||
3383 | return ((iter->head_page == commit_page && iter->head == commit) || | |
3384 | (iter->head_page == reader && commit_page == head_page && | |
3385 | head_page->read == commit && | |
3386 | iter->head == rb_page_commit(cpu_buffer->reader_page))); | |
7a8e76a3 | 3387 | } |
c4f50183 | 3388 | EXPORT_SYMBOL_GPL(ring_buffer_iter_empty); |
7a8e76a3 SR |
3389 | |
3390 | static void | |
3391 | rb_update_read_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
3392 | struct ring_buffer_event *event) | |
3393 | { | |
3394 | u64 delta; | |
3395 | ||
334d4169 | 3396 | switch (event->type_len) { |
7a8e76a3 SR |
3397 | case RINGBUF_TYPE_PADDING: |
3398 | return; | |
3399 | ||
3400 | case RINGBUF_TYPE_TIME_EXTEND: | |
3401 | delta = event->array[0]; | |
3402 | delta <<= TS_SHIFT; | |
3403 | delta += event->time_delta; | |
3404 | cpu_buffer->read_stamp += delta; | |
3405 | return; | |
3406 | ||
3407 | case RINGBUF_TYPE_TIME_STAMP: | |
3408 | /* FIXME: not implemented */ | |
3409 | return; | |
3410 | ||
3411 | case RINGBUF_TYPE_DATA: | |
3412 | cpu_buffer->read_stamp += event->time_delta; | |
3413 | return; | |
3414 | ||
3415 | default: | |
3416 | BUG(); | |
3417 | } | |
3418 | return; | |
3419 | } | |
3420 | ||
3421 | static void | |
3422 | rb_update_iter_read_stamp(struct ring_buffer_iter *iter, | |
3423 | struct ring_buffer_event *event) | |
3424 | { | |
3425 | u64 delta; | |
3426 | ||
334d4169 | 3427 | switch (event->type_len) { |
7a8e76a3 SR |
3428 | case RINGBUF_TYPE_PADDING: |
3429 | return; | |
3430 | ||
3431 | case RINGBUF_TYPE_TIME_EXTEND: | |
3432 | delta = event->array[0]; | |
3433 | delta <<= TS_SHIFT; | |
3434 | delta += event->time_delta; | |
3435 | iter->read_stamp += delta; | |
3436 | return; | |
3437 | ||
3438 | case RINGBUF_TYPE_TIME_STAMP: | |
3439 | /* FIXME: not implemented */ | |
3440 | return; | |
3441 | ||
3442 | case RINGBUF_TYPE_DATA: | |
3443 | iter->read_stamp += event->time_delta; | |
3444 | return; | |
3445 | ||
3446 | default: | |
3447 | BUG(); | |
3448 | } | |
3449 | return; | |
3450 | } | |
3451 | ||
d769041f SR |
3452 | static struct buffer_page * |
3453 | rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) | |
7a8e76a3 | 3454 | { |
d769041f | 3455 | struct buffer_page *reader = NULL; |
66a8cb95 | 3456 | unsigned long overwrite; |
d769041f | 3457 | unsigned long flags; |
818e3dd3 | 3458 | int nr_loops = 0; |
77ae365e | 3459 | int ret; |
d769041f | 3460 | |
3e03fb7f | 3461 | local_irq_save(flags); |
0199c4e6 | 3462 | arch_spin_lock(&cpu_buffer->lock); |
d769041f SR |
3463 | |
3464 | again: | |
818e3dd3 SR |
3465 | /* |
3466 | * This should normally only loop twice. But because the | |
3467 | * start of the reader inserts an empty page, it causes | |
3468 | * a case where we will loop three times. There should be no | |
3469 | * reason to loop four times (that I know of). | |
3470 | */ | |
3e89c7bb | 3471 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 3)) { |
818e3dd3 SR |
3472 | reader = NULL; |
3473 | goto out; | |
3474 | } | |
3475 | ||
d769041f SR |
3476 | reader = cpu_buffer->reader_page; |
3477 | ||
3478 | /* If there's more to read, return this page */ | |
bf41a158 | 3479 | if (cpu_buffer->reader_page->read < rb_page_size(reader)) |
d769041f SR |
3480 | goto out; |
3481 | ||
3482 | /* Never should we have an index greater than the size */ | |
3e89c7bb SR |
3483 | if (RB_WARN_ON(cpu_buffer, |
3484 | cpu_buffer->reader_page->read > rb_page_size(reader))) | |
3485 | goto out; | |
d769041f SR |
3486 | |
3487 | /* check if we caught up to the tail */ | |
3488 | reader = NULL; | |
bf41a158 | 3489 | if (cpu_buffer->commit_page == cpu_buffer->reader_page) |
d769041f | 3490 | goto out; |
7a8e76a3 | 3491 | |
a5fb8331 SR |
3492 | /* Don't bother swapping if the ring buffer is empty */ |
3493 | if (rb_num_of_entries(cpu_buffer) == 0) | |
3494 | goto out; | |
3495 | ||
7a8e76a3 | 3496 | /* |
d769041f | 3497 | * Reset the reader page to size zero. |
7a8e76a3 | 3498 | */ |
77ae365e SR |
3499 | local_set(&cpu_buffer->reader_page->write, 0); |
3500 | local_set(&cpu_buffer->reader_page->entries, 0); | |
3501 | local_set(&cpu_buffer->reader_page->page->commit, 0); | |
ff0ff84a | 3502 | cpu_buffer->reader_page->real_end = 0; |
7a8e76a3 | 3503 | |
77ae365e SR |
3504 | spin: |
3505 | /* | |
3506 | * Splice the empty reader page into the list around the head. | |
3507 | */ | |
3508 | reader = rb_set_head_page(cpu_buffer); | |
54f7be5b SR |
3509 | if (!reader) |
3510 | goto out; | |
0e1ff5d7 | 3511 | cpu_buffer->reader_page->list.next = rb_list_head(reader->list.next); |
d769041f | 3512 | cpu_buffer->reader_page->list.prev = reader->list.prev; |
bf41a158 | 3513 | |
3adc54fa SR |
3514 | /* |
3515 | * cpu_buffer->pages just needs to point to the buffer, it | |
3516 | * has no specific buffer page to point to. Lets move it out | |
25985edc | 3517 | * of our way so we don't accidentally swap it. |
3adc54fa SR |
3518 | */ |
3519 | cpu_buffer->pages = reader->list.prev; | |
3520 | ||
77ae365e SR |
3521 | /* The reader page will be pointing to the new head */ |
3522 | rb_set_list_to_head(cpu_buffer, &cpu_buffer->reader_page->list); | |
7a8e76a3 | 3523 | |
66a8cb95 SR |
3524 | /* |
3525 | * We want to make sure we read the overruns after we set up our | |
3526 | * pointers to the next object. The writer side does a | |
3527 | * cmpxchg to cross pages which acts as the mb on the writer | |
3528 | * side. Note, the reader will constantly fail the swap | |
3529 | * while the writer is updating the pointers, so this | |
3530 | * guarantees that the overwrite recorded here is the one we | |
3531 | * want to compare with the last_overrun. | |
3532 | */ | |
3533 | smp_mb(); | |
3534 | overwrite = local_read(&(cpu_buffer->overrun)); | |
3535 | ||
77ae365e SR |
3536 | /* |
3537 | * Here's the tricky part. | |
3538 | * | |
3539 | * We need to move the pointer past the header page. | |
3540 | * But we can only do that if a writer is not currently | |
3541 | * moving it. The page before the header page has the | |
3542 | * flag bit '1' set if it is pointing to the page we want. | |
3543 | * but if the writer is in the process of moving it | |
3544 | * than it will be '2' or already moved '0'. | |
3545 | */ | |
3546 | ||
3547 | ret = rb_head_page_replace(reader, cpu_buffer->reader_page); | |
7a8e76a3 SR |
3548 | |
3549 | /* | |
77ae365e | 3550 | * If we did not convert it, then we must try again. |
7a8e76a3 | 3551 | */ |
77ae365e SR |
3552 | if (!ret) |
3553 | goto spin; | |
7a8e76a3 | 3554 | |
77ae365e SR |
3555 | /* |
3556 | * Yeah! We succeeded in replacing the page. | |
3557 | * | |
3558 | * Now make the new head point back to the reader page. | |
3559 | */ | |
5ded3dc6 | 3560 | rb_list_head(reader->list.next)->prev = &cpu_buffer->reader_page->list; |
77ae365e | 3561 | rb_inc_page(cpu_buffer, &cpu_buffer->head_page); |
d769041f SR |
3562 | |
3563 | /* Finally update the reader page to the new head */ | |
3564 | cpu_buffer->reader_page = reader; | |
b81f472a | 3565 | cpu_buffer->reader_page->read = 0; |
d769041f | 3566 | |
66a8cb95 SR |
3567 | if (overwrite != cpu_buffer->last_overrun) { |
3568 | cpu_buffer->lost_events = overwrite - cpu_buffer->last_overrun; | |
3569 | cpu_buffer->last_overrun = overwrite; | |
3570 | } | |
3571 | ||
d769041f SR |
3572 | goto again; |
3573 | ||
3574 | out: | |
b81f472a SRRH |
3575 | /* Update the read_stamp on the first event */ |
3576 | if (reader && reader->read == 0) | |
3577 | cpu_buffer->read_stamp = reader->page->time_stamp; | |
3578 | ||
0199c4e6 | 3579 | arch_spin_unlock(&cpu_buffer->lock); |
3e03fb7f | 3580 | local_irq_restore(flags); |
d769041f SR |
3581 | |
3582 | return reader; | |
3583 | } | |
3584 | ||
3585 | static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer) | |
3586 | { | |
3587 | struct ring_buffer_event *event; | |
3588 | struct buffer_page *reader; | |
3589 | unsigned length; | |
3590 | ||
3591 | reader = rb_get_reader_page(cpu_buffer); | |
7a8e76a3 | 3592 | |
d769041f | 3593 | /* This function should not be called when buffer is empty */ |
3e89c7bb SR |
3594 | if (RB_WARN_ON(cpu_buffer, !reader)) |
3595 | return; | |
7a8e76a3 | 3596 | |
d769041f SR |
3597 | event = rb_reader_event(cpu_buffer); |
3598 | ||
a1863c21 | 3599 | if (event->type_len <= RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
e4906eff | 3600 | cpu_buffer->read++; |
d769041f SR |
3601 | |
3602 | rb_update_read_stamp(cpu_buffer, event); | |
3603 | ||
3604 | length = rb_event_length(event); | |
6f807acd | 3605 | cpu_buffer->reader_page->read += length; |
7a8e76a3 SR |
3606 | } |
3607 | ||
3608 | static void rb_advance_iter(struct ring_buffer_iter *iter) | |
3609 | { | |
7a8e76a3 SR |
3610 | struct ring_buffer_per_cpu *cpu_buffer; |
3611 | struct ring_buffer_event *event; | |
3612 | unsigned length; | |
3613 | ||
3614 | cpu_buffer = iter->cpu_buffer; | |
7a8e76a3 SR |
3615 | |
3616 | /* | |
3617 | * Check if we are at the end of the buffer. | |
3618 | */ | |
bf41a158 | 3619 | if (iter->head >= rb_page_size(iter->head_page)) { |
ea05b57c SR |
3620 | /* discarded commits can make the page empty */ |
3621 | if (iter->head_page == cpu_buffer->commit_page) | |
3e89c7bb | 3622 | return; |
d769041f | 3623 | rb_inc_iter(iter); |
7a8e76a3 SR |
3624 | return; |
3625 | } | |
3626 | ||
3627 | event = rb_iter_head_event(iter); | |
3628 | ||
3629 | length = rb_event_length(event); | |
3630 | ||
3631 | /* | |
3632 | * This should not be called to advance the header if we are | |
3633 | * at the tail of the buffer. | |
3634 | */ | |
3e89c7bb | 3635 | if (RB_WARN_ON(cpu_buffer, |
f536aafc | 3636 | (iter->head_page == cpu_buffer->commit_page) && |
3e89c7bb SR |
3637 | (iter->head + length > rb_commit_index(cpu_buffer)))) |
3638 | return; | |
7a8e76a3 SR |
3639 | |
3640 | rb_update_iter_read_stamp(iter, event); | |
3641 | ||
3642 | iter->head += length; | |
3643 | ||
3644 | /* check for end of page padding */ | |
bf41a158 SR |
3645 | if ((iter->head >= rb_page_size(iter->head_page)) && |
3646 | (iter->head_page != cpu_buffer->commit_page)) | |
771e0384 | 3647 | rb_inc_iter(iter); |
7a8e76a3 SR |
3648 | } |
3649 | ||
66a8cb95 SR |
3650 | static int rb_lost_events(struct ring_buffer_per_cpu *cpu_buffer) |
3651 | { | |
3652 | return cpu_buffer->lost_events; | |
3653 | } | |
3654 | ||
f83c9d0f | 3655 | static struct ring_buffer_event * |
66a8cb95 SR |
3656 | rb_buffer_peek(struct ring_buffer_per_cpu *cpu_buffer, u64 *ts, |
3657 | unsigned long *lost_events) | |
7a8e76a3 | 3658 | { |
7a8e76a3 | 3659 | struct ring_buffer_event *event; |
d769041f | 3660 | struct buffer_page *reader; |
818e3dd3 | 3661 | int nr_loops = 0; |
7a8e76a3 | 3662 | |
7a8e76a3 | 3663 | again: |
818e3dd3 | 3664 | /* |
69d1b839 SR |
3665 | * We repeat when a time extend is encountered. |
3666 | * Since the time extend is always attached to a data event, | |
3667 | * we should never loop more than once. | |
3668 | * (We never hit the following condition more than twice). | |
818e3dd3 | 3669 | */ |
69d1b839 | 3670 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 2)) |
818e3dd3 | 3671 | return NULL; |
818e3dd3 | 3672 | |
d769041f SR |
3673 | reader = rb_get_reader_page(cpu_buffer); |
3674 | if (!reader) | |
7a8e76a3 SR |
3675 | return NULL; |
3676 | ||
d769041f | 3677 | event = rb_reader_event(cpu_buffer); |
7a8e76a3 | 3678 | |
334d4169 | 3679 | switch (event->type_len) { |
7a8e76a3 | 3680 | case RINGBUF_TYPE_PADDING: |
2d622719 TZ |
3681 | if (rb_null_event(event)) |
3682 | RB_WARN_ON(cpu_buffer, 1); | |
3683 | /* | |
3684 | * Because the writer could be discarding every | |
3685 | * event it creates (which would probably be bad) | |
3686 | * if we were to go back to "again" then we may never | |
3687 | * catch up, and will trigger the warn on, or lock | |
3688 | * the box. Return the padding, and we will release | |
3689 | * the current locks, and try again. | |
3690 | */ | |
2d622719 | 3691 | return event; |
7a8e76a3 SR |
3692 | |
3693 | case RINGBUF_TYPE_TIME_EXTEND: | |
3694 | /* Internal data, OK to advance */ | |
d769041f | 3695 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
3696 | goto again; |
3697 | ||
3698 | case RINGBUF_TYPE_TIME_STAMP: | |
3699 | /* FIXME: not implemented */ | |
d769041f | 3700 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
3701 | goto again; |
3702 | ||
3703 | case RINGBUF_TYPE_DATA: | |
3704 | if (ts) { | |
3705 | *ts = cpu_buffer->read_stamp + event->time_delta; | |
d8eeb2d3 | 3706 | ring_buffer_normalize_time_stamp(cpu_buffer->buffer, |
37886f6a | 3707 | cpu_buffer->cpu, ts); |
7a8e76a3 | 3708 | } |
66a8cb95 SR |
3709 | if (lost_events) |
3710 | *lost_events = rb_lost_events(cpu_buffer); | |
7a8e76a3 SR |
3711 | return event; |
3712 | ||
3713 | default: | |
3714 | BUG(); | |
3715 | } | |
3716 | ||
3717 | return NULL; | |
3718 | } | |
c4f50183 | 3719 | EXPORT_SYMBOL_GPL(ring_buffer_peek); |
7a8e76a3 | 3720 | |
f83c9d0f SR |
3721 | static struct ring_buffer_event * |
3722 | rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) | |
7a8e76a3 SR |
3723 | { |
3724 | struct ring_buffer *buffer; | |
3725 | struct ring_buffer_per_cpu *cpu_buffer; | |
3726 | struct ring_buffer_event *event; | |
818e3dd3 | 3727 | int nr_loops = 0; |
7a8e76a3 | 3728 | |
7a8e76a3 SR |
3729 | cpu_buffer = iter->cpu_buffer; |
3730 | buffer = cpu_buffer->buffer; | |
3731 | ||
492a74f4 SR |
3732 | /* |
3733 | * Check if someone performed a consuming read to | |
3734 | * the buffer. A consuming read invalidates the iterator | |
3735 | * and we need to reset the iterator in this case. | |
3736 | */ | |
3737 | if (unlikely(iter->cache_read != cpu_buffer->read || | |
3738 | iter->cache_reader_page != cpu_buffer->reader_page)) | |
3739 | rb_iter_reset(iter); | |
3740 | ||
7a8e76a3 | 3741 | again: |
3c05d748 SR |
3742 | if (ring_buffer_iter_empty(iter)) |
3743 | return NULL; | |
3744 | ||
818e3dd3 | 3745 | /* |
021de3d9 SRRH |
3746 | * We repeat when a time extend is encountered or we hit |
3747 | * the end of the page. Since the time extend is always attached | |
3748 | * to a data event, we should never loop more than three times. | |
3749 | * Once for going to next page, once on time extend, and | |
3750 | * finally once to get the event. | |
3751 | * (We never hit the following condition more than thrice). | |
818e3dd3 | 3752 | */ |
021de3d9 | 3753 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 3)) |
818e3dd3 | 3754 | return NULL; |
818e3dd3 | 3755 | |
7a8e76a3 SR |
3756 | if (rb_per_cpu_empty(cpu_buffer)) |
3757 | return NULL; | |
3758 | ||
10e83fd0 | 3759 | if (iter->head >= rb_page_size(iter->head_page)) { |
3c05d748 SR |
3760 | rb_inc_iter(iter); |
3761 | goto again; | |
3762 | } | |
3763 | ||
7a8e76a3 SR |
3764 | event = rb_iter_head_event(iter); |
3765 | ||
334d4169 | 3766 | switch (event->type_len) { |
7a8e76a3 | 3767 | case RINGBUF_TYPE_PADDING: |
2d622719 TZ |
3768 | if (rb_null_event(event)) { |
3769 | rb_inc_iter(iter); | |
3770 | goto again; | |
3771 | } | |
3772 | rb_advance_iter(iter); | |
3773 | return event; | |
7a8e76a3 SR |
3774 | |
3775 | case RINGBUF_TYPE_TIME_EXTEND: | |
3776 | /* Internal data, OK to advance */ | |
3777 | rb_advance_iter(iter); | |
3778 | goto again; | |
3779 | ||
3780 | case RINGBUF_TYPE_TIME_STAMP: | |
3781 | /* FIXME: not implemented */ | |
3782 | rb_advance_iter(iter); | |
3783 | goto again; | |
3784 | ||
3785 | case RINGBUF_TYPE_DATA: | |
3786 | if (ts) { | |
3787 | *ts = iter->read_stamp + event->time_delta; | |
37886f6a SR |
3788 | ring_buffer_normalize_time_stamp(buffer, |
3789 | cpu_buffer->cpu, ts); | |
7a8e76a3 SR |
3790 | } |
3791 | return event; | |
3792 | ||
3793 | default: | |
3794 | BUG(); | |
3795 | } | |
3796 | ||
3797 | return NULL; | |
3798 | } | |
c4f50183 | 3799 | EXPORT_SYMBOL_GPL(ring_buffer_iter_peek); |
7a8e76a3 | 3800 | |
289a5a25 | 3801 | static inline bool rb_reader_lock(struct ring_buffer_per_cpu *cpu_buffer) |
8d707e8e | 3802 | { |
289a5a25 SRRH |
3803 | if (likely(!in_nmi())) { |
3804 | raw_spin_lock(&cpu_buffer->reader_lock); | |
3805 | return true; | |
3806 | } | |
3807 | ||
8d707e8e SR |
3808 | /* |
3809 | * If an NMI die dumps out the content of the ring buffer | |
289a5a25 SRRH |
3810 | * trylock must be used to prevent a deadlock if the NMI |
3811 | * preempted a task that holds the ring buffer locks. If | |
3812 | * we get the lock then all is fine, if not, then continue | |
3813 | * to do the read, but this can corrupt the ring buffer, | |
3814 | * so it must be permanently disabled from future writes. | |
3815 | * Reading from NMI is a oneshot deal. | |
8d707e8e | 3816 | */ |
289a5a25 SRRH |
3817 | if (raw_spin_trylock(&cpu_buffer->reader_lock)) |
3818 | return true; | |
8d707e8e | 3819 | |
289a5a25 SRRH |
3820 | /* Continue without locking, but disable the ring buffer */ |
3821 | atomic_inc(&cpu_buffer->record_disabled); | |
3822 | return false; | |
3823 | } | |
3824 | ||
3825 | static inline void | |
3826 | rb_reader_unlock(struct ring_buffer_per_cpu *cpu_buffer, bool locked) | |
3827 | { | |
3828 | if (likely(locked)) | |
3829 | raw_spin_unlock(&cpu_buffer->reader_lock); | |
3830 | return; | |
8d707e8e SR |
3831 | } |
3832 | ||
f83c9d0f SR |
3833 | /** |
3834 | * ring_buffer_peek - peek at the next event to be read | |
3835 | * @buffer: The ring buffer to read | |
3836 | * @cpu: The cpu to peak at | |
3837 | * @ts: The timestamp counter of this event. | |
66a8cb95 | 3838 | * @lost_events: a variable to store if events were lost (may be NULL) |
f83c9d0f SR |
3839 | * |
3840 | * This will return the event that will be read next, but does | |
3841 | * not consume the data. | |
3842 | */ | |
3843 | struct ring_buffer_event * | |
66a8cb95 SR |
3844 | ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts, |
3845 | unsigned long *lost_events) | |
f83c9d0f SR |
3846 | { |
3847 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
8aabee57 | 3848 | struct ring_buffer_event *event; |
f83c9d0f | 3849 | unsigned long flags; |
289a5a25 | 3850 | bool dolock; |
f83c9d0f | 3851 | |
554f786e | 3852 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 3853 | return NULL; |
554f786e | 3854 | |
2d622719 | 3855 | again: |
8d707e8e | 3856 | local_irq_save(flags); |
289a5a25 | 3857 | dolock = rb_reader_lock(cpu_buffer); |
66a8cb95 | 3858 | event = rb_buffer_peek(cpu_buffer, ts, lost_events); |
469535a5 RR |
3859 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
3860 | rb_advance_reader(cpu_buffer); | |
289a5a25 | 3861 | rb_reader_unlock(cpu_buffer, dolock); |
8d707e8e | 3862 | local_irq_restore(flags); |
f83c9d0f | 3863 | |
1b959e18 | 3864 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
2d622719 | 3865 | goto again; |
2d622719 | 3866 | |
f83c9d0f SR |
3867 | return event; |
3868 | } | |
3869 | ||
3870 | /** | |
3871 | * ring_buffer_iter_peek - peek at the next event to be read | |
3872 | * @iter: The ring buffer iterator | |
3873 | * @ts: The timestamp counter of this event. | |
3874 | * | |
3875 | * This will return the event that will be read next, but does | |
3876 | * not increment the iterator. | |
3877 | */ | |
3878 | struct ring_buffer_event * | |
3879 | ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) | |
3880 | { | |
3881 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
3882 | struct ring_buffer_event *event; | |
3883 | unsigned long flags; | |
3884 | ||
2d622719 | 3885 | again: |
5389f6fa | 3886 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
f83c9d0f | 3887 | event = rb_iter_peek(iter, ts); |
5389f6fa | 3888 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
f83c9d0f | 3889 | |
1b959e18 | 3890 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
2d622719 | 3891 | goto again; |
2d622719 | 3892 | |
f83c9d0f SR |
3893 | return event; |
3894 | } | |
3895 | ||
7a8e76a3 SR |
3896 | /** |
3897 | * ring_buffer_consume - return an event and consume it | |
3898 | * @buffer: The ring buffer to get the next event from | |
66a8cb95 SR |
3899 | * @cpu: the cpu to read the buffer from |
3900 | * @ts: a variable to store the timestamp (may be NULL) | |
3901 | * @lost_events: a variable to store if events were lost (may be NULL) | |
7a8e76a3 SR |
3902 | * |
3903 | * Returns the next event in the ring buffer, and that event is consumed. | |
3904 | * Meaning, that sequential reads will keep returning a different event, | |
3905 | * and eventually empty the ring buffer if the producer is slower. | |
3906 | */ | |
3907 | struct ring_buffer_event * | |
66a8cb95 SR |
3908 | ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts, |
3909 | unsigned long *lost_events) | |
7a8e76a3 | 3910 | { |
554f786e SR |
3911 | struct ring_buffer_per_cpu *cpu_buffer; |
3912 | struct ring_buffer_event *event = NULL; | |
f83c9d0f | 3913 | unsigned long flags; |
289a5a25 | 3914 | bool dolock; |
7a8e76a3 | 3915 | |
2d622719 | 3916 | again: |
554f786e SR |
3917 | /* might be called in atomic */ |
3918 | preempt_disable(); | |
3919 | ||
9e01c1b7 | 3920 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
554f786e | 3921 | goto out; |
7a8e76a3 | 3922 | |
554f786e | 3923 | cpu_buffer = buffer->buffers[cpu]; |
8d707e8e | 3924 | local_irq_save(flags); |
289a5a25 | 3925 | dolock = rb_reader_lock(cpu_buffer); |
f83c9d0f | 3926 | |
66a8cb95 SR |
3927 | event = rb_buffer_peek(cpu_buffer, ts, lost_events); |
3928 | if (event) { | |
3929 | cpu_buffer->lost_events = 0; | |
469535a5 | 3930 | rb_advance_reader(cpu_buffer); |
66a8cb95 | 3931 | } |
7a8e76a3 | 3932 | |
289a5a25 | 3933 | rb_reader_unlock(cpu_buffer, dolock); |
8d707e8e | 3934 | local_irq_restore(flags); |
f83c9d0f | 3935 | |
554f786e SR |
3936 | out: |
3937 | preempt_enable(); | |
3938 | ||
1b959e18 | 3939 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
2d622719 | 3940 | goto again; |
2d622719 | 3941 | |
7a8e76a3 SR |
3942 | return event; |
3943 | } | |
c4f50183 | 3944 | EXPORT_SYMBOL_GPL(ring_buffer_consume); |
7a8e76a3 SR |
3945 | |
3946 | /** | |
72c9ddfd | 3947 | * ring_buffer_read_prepare - Prepare for a non consuming read of the buffer |
7a8e76a3 SR |
3948 | * @buffer: The ring buffer to read from |
3949 | * @cpu: The cpu buffer to iterate over | |
3950 | * | |
72c9ddfd DM |
3951 | * This performs the initial preparations necessary to iterate |
3952 | * through the buffer. Memory is allocated, buffer recording | |
3953 | * is disabled, and the iterator pointer is returned to the caller. | |
7a8e76a3 | 3954 | * |
72c9ddfd DM |
3955 | * Disabling buffer recordng prevents the reading from being |
3956 | * corrupted. This is not a consuming read, so a producer is not | |
3957 | * expected. | |
3958 | * | |
3959 | * After a sequence of ring_buffer_read_prepare calls, the user is | |
d611851b | 3960 | * expected to make at least one call to ring_buffer_read_prepare_sync. |
72c9ddfd DM |
3961 | * Afterwards, ring_buffer_read_start is invoked to get things going |
3962 | * for real. | |
3963 | * | |
d611851b | 3964 | * This overall must be paired with ring_buffer_read_finish. |
7a8e76a3 SR |
3965 | */ |
3966 | struct ring_buffer_iter * | |
72c9ddfd | 3967 | ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu) |
7a8e76a3 SR |
3968 | { |
3969 | struct ring_buffer_per_cpu *cpu_buffer; | |
8aabee57 | 3970 | struct ring_buffer_iter *iter; |
7a8e76a3 | 3971 | |
9e01c1b7 | 3972 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 3973 | return NULL; |
7a8e76a3 SR |
3974 | |
3975 | iter = kmalloc(sizeof(*iter), GFP_KERNEL); | |
3976 | if (!iter) | |
8aabee57 | 3977 | return NULL; |
7a8e76a3 SR |
3978 | |
3979 | cpu_buffer = buffer->buffers[cpu]; | |
3980 | ||
3981 | iter->cpu_buffer = cpu_buffer; | |
3982 | ||
83f40318 | 3983 | atomic_inc(&buffer->resize_disabled); |
7a8e76a3 | 3984 | atomic_inc(&cpu_buffer->record_disabled); |
72c9ddfd DM |
3985 | |
3986 | return iter; | |
3987 | } | |
3988 | EXPORT_SYMBOL_GPL(ring_buffer_read_prepare); | |
3989 | ||
3990 | /** | |
3991 | * ring_buffer_read_prepare_sync - Synchronize a set of prepare calls | |
3992 | * | |
3993 | * All previously invoked ring_buffer_read_prepare calls to prepare | |
3994 | * iterators will be synchronized. Afterwards, read_buffer_read_start | |
3995 | * calls on those iterators are allowed. | |
3996 | */ | |
3997 | void | |
3998 | ring_buffer_read_prepare_sync(void) | |
3999 | { | |
7a8e76a3 | 4000 | synchronize_sched(); |
72c9ddfd DM |
4001 | } |
4002 | EXPORT_SYMBOL_GPL(ring_buffer_read_prepare_sync); | |
4003 | ||
4004 | /** | |
4005 | * ring_buffer_read_start - start a non consuming read of the buffer | |
4006 | * @iter: The iterator returned by ring_buffer_read_prepare | |
4007 | * | |
4008 | * This finalizes the startup of an iteration through the buffer. | |
4009 | * The iterator comes from a call to ring_buffer_read_prepare and | |
4010 | * an intervening ring_buffer_read_prepare_sync must have been | |
4011 | * performed. | |
4012 | * | |
d611851b | 4013 | * Must be paired with ring_buffer_read_finish. |
72c9ddfd DM |
4014 | */ |
4015 | void | |
4016 | ring_buffer_read_start(struct ring_buffer_iter *iter) | |
4017 | { | |
4018 | struct ring_buffer_per_cpu *cpu_buffer; | |
4019 | unsigned long flags; | |
4020 | ||
4021 | if (!iter) | |
4022 | return; | |
4023 | ||
4024 | cpu_buffer = iter->cpu_buffer; | |
7a8e76a3 | 4025 | |
5389f6fa | 4026 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
0199c4e6 | 4027 | arch_spin_lock(&cpu_buffer->lock); |
642edba5 | 4028 | rb_iter_reset(iter); |
0199c4e6 | 4029 | arch_spin_unlock(&cpu_buffer->lock); |
5389f6fa | 4030 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
7a8e76a3 | 4031 | } |
c4f50183 | 4032 | EXPORT_SYMBOL_GPL(ring_buffer_read_start); |
7a8e76a3 SR |
4033 | |
4034 | /** | |
d611851b | 4035 | * ring_buffer_read_finish - finish reading the iterator of the buffer |
7a8e76a3 SR |
4036 | * @iter: The iterator retrieved by ring_buffer_start |
4037 | * | |
4038 | * This re-enables the recording to the buffer, and frees the | |
4039 | * iterator. | |
4040 | */ | |
4041 | void | |
4042 | ring_buffer_read_finish(struct ring_buffer_iter *iter) | |
4043 | { | |
4044 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
9366c1ba | 4045 | unsigned long flags; |
7a8e76a3 | 4046 | |
659f451f SR |
4047 | /* |
4048 | * Ring buffer is disabled from recording, here's a good place | |
9366c1ba SR |
4049 | * to check the integrity of the ring buffer. |
4050 | * Must prevent readers from trying to read, as the check | |
4051 | * clears the HEAD page and readers require it. | |
659f451f | 4052 | */ |
9366c1ba | 4053 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
659f451f | 4054 | rb_check_pages(cpu_buffer); |
9366c1ba | 4055 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
659f451f | 4056 | |
7a8e76a3 | 4057 | atomic_dec(&cpu_buffer->record_disabled); |
83f40318 | 4058 | atomic_dec(&cpu_buffer->buffer->resize_disabled); |
7a8e76a3 SR |
4059 | kfree(iter); |
4060 | } | |
c4f50183 | 4061 | EXPORT_SYMBOL_GPL(ring_buffer_read_finish); |
7a8e76a3 SR |
4062 | |
4063 | /** | |
4064 | * ring_buffer_read - read the next item in the ring buffer by the iterator | |
4065 | * @iter: The ring buffer iterator | |
4066 | * @ts: The time stamp of the event read. | |
4067 | * | |
4068 | * This reads the next event in the ring buffer and increments the iterator. | |
4069 | */ | |
4070 | struct ring_buffer_event * | |
4071 | ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) | |
4072 | { | |
4073 | struct ring_buffer_event *event; | |
f83c9d0f SR |
4074 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
4075 | unsigned long flags; | |
7a8e76a3 | 4076 | |
5389f6fa | 4077 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
7e9391cf | 4078 | again: |
f83c9d0f | 4079 | event = rb_iter_peek(iter, ts); |
7a8e76a3 | 4080 | if (!event) |
f83c9d0f | 4081 | goto out; |
7a8e76a3 | 4082 | |
7e9391cf SR |
4083 | if (event->type_len == RINGBUF_TYPE_PADDING) |
4084 | goto again; | |
4085 | ||
7a8e76a3 | 4086 | rb_advance_iter(iter); |
f83c9d0f | 4087 | out: |
5389f6fa | 4088 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
7a8e76a3 SR |
4089 | |
4090 | return event; | |
4091 | } | |
c4f50183 | 4092 | EXPORT_SYMBOL_GPL(ring_buffer_read); |
7a8e76a3 SR |
4093 | |
4094 | /** | |
4095 | * ring_buffer_size - return the size of the ring buffer (in bytes) | |
4096 | * @buffer: The ring buffer. | |
4097 | */ | |
438ced17 | 4098 | unsigned long ring_buffer_size(struct ring_buffer *buffer, int cpu) |
7a8e76a3 | 4099 | { |
438ced17 VN |
4100 | /* |
4101 | * Earlier, this method returned | |
4102 | * BUF_PAGE_SIZE * buffer->nr_pages | |
4103 | * Since the nr_pages field is now removed, we have converted this to | |
4104 | * return the per cpu buffer value. | |
4105 | */ | |
4106 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
4107 | return 0; | |
4108 | ||
4109 | return BUF_PAGE_SIZE * buffer->buffers[cpu]->nr_pages; | |
7a8e76a3 | 4110 | } |
c4f50183 | 4111 | EXPORT_SYMBOL_GPL(ring_buffer_size); |
7a8e76a3 SR |
4112 | |
4113 | static void | |
4114 | rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) | |
4115 | { | |
77ae365e SR |
4116 | rb_head_page_deactivate(cpu_buffer); |
4117 | ||
7a8e76a3 | 4118 | cpu_buffer->head_page |
3adc54fa | 4119 | = list_entry(cpu_buffer->pages, struct buffer_page, list); |
bf41a158 | 4120 | local_set(&cpu_buffer->head_page->write, 0); |
778c55d4 | 4121 | local_set(&cpu_buffer->head_page->entries, 0); |
abc9b56d | 4122 | local_set(&cpu_buffer->head_page->page->commit, 0); |
d769041f | 4123 | |
6f807acd | 4124 | cpu_buffer->head_page->read = 0; |
bf41a158 SR |
4125 | |
4126 | cpu_buffer->tail_page = cpu_buffer->head_page; | |
4127 | cpu_buffer->commit_page = cpu_buffer->head_page; | |
4128 | ||
4129 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); | |
5040b4b7 | 4130 | INIT_LIST_HEAD(&cpu_buffer->new_pages); |
bf41a158 | 4131 | local_set(&cpu_buffer->reader_page->write, 0); |
778c55d4 | 4132 | local_set(&cpu_buffer->reader_page->entries, 0); |
abc9b56d | 4133 | local_set(&cpu_buffer->reader_page->page->commit, 0); |
6f807acd | 4134 | cpu_buffer->reader_page->read = 0; |
7a8e76a3 | 4135 | |
c64e148a | 4136 | local_set(&cpu_buffer->entries_bytes, 0); |
77ae365e | 4137 | local_set(&cpu_buffer->overrun, 0); |
884bfe89 SP |
4138 | local_set(&cpu_buffer->commit_overrun, 0); |
4139 | local_set(&cpu_buffer->dropped_events, 0); | |
e4906eff | 4140 | local_set(&cpu_buffer->entries, 0); |
fa743953 SR |
4141 | local_set(&cpu_buffer->committing, 0); |
4142 | local_set(&cpu_buffer->commits, 0); | |
77ae365e | 4143 | cpu_buffer->read = 0; |
c64e148a | 4144 | cpu_buffer->read_bytes = 0; |
69507c06 SR |
4145 | |
4146 | cpu_buffer->write_stamp = 0; | |
4147 | cpu_buffer->read_stamp = 0; | |
77ae365e | 4148 | |
66a8cb95 SR |
4149 | cpu_buffer->lost_events = 0; |
4150 | cpu_buffer->last_overrun = 0; | |
4151 | ||
77ae365e | 4152 | rb_head_page_activate(cpu_buffer); |
7a8e76a3 SR |
4153 | } |
4154 | ||
4155 | /** | |
4156 | * ring_buffer_reset_cpu - reset a ring buffer per CPU buffer | |
4157 | * @buffer: The ring buffer to reset a per cpu buffer of | |
4158 | * @cpu: The CPU buffer to be reset | |
4159 | */ | |
4160 | void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) | |
4161 | { | |
4162 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
4163 | unsigned long flags; | |
4164 | ||
9e01c1b7 | 4165 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 4166 | return; |
7a8e76a3 | 4167 | |
83f40318 | 4168 | atomic_inc(&buffer->resize_disabled); |
41ede23e SR |
4169 | atomic_inc(&cpu_buffer->record_disabled); |
4170 | ||
83f40318 VN |
4171 | /* Make sure all commits have finished */ |
4172 | synchronize_sched(); | |
4173 | ||
5389f6fa | 4174 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
f83c9d0f | 4175 | |
41b6a95d SR |
4176 | if (RB_WARN_ON(cpu_buffer, local_read(&cpu_buffer->committing))) |
4177 | goto out; | |
4178 | ||
0199c4e6 | 4179 | arch_spin_lock(&cpu_buffer->lock); |
7a8e76a3 SR |
4180 | |
4181 | rb_reset_cpu(cpu_buffer); | |
4182 | ||
0199c4e6 | 4183 | arch_spin_unlock(&cpu_buffer->lock); |
f83c9d0f | 4184 | |
41b6a95d | 4185 | out: |
5389f6fa | 4186 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
41ede23e SR |
4187 | |
4188 | atomic_dec(&cpu_buffer->record_disabled); | |
83f40318 | 4189 | atomic_dec(&buffer->resize_disabled); |
7a8e76a3 | 4190 | } |
c4f50183 | 4191 | EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); |
7a8e76a3 SR |
4192 | |
4193 | /** | |
4194 | * ring_buffer_reset - reset a ring buffer | |
4195 | * @buffer: The ring buffer to reset all cpu buffers | |
4196 | */ | |
4197 | void ring_buffer_reset(struct ring_buffer *buffer) | |
4198 | { | |
7a8e76a3 SR |
4199 | int cpu; |
4200 | ||
7a8e76a3 | 4201 | for_each_buffer_cpu(buffer, cpu) |
d769041f | 4202 | ring_buffer_reset_cpu(buffer, cpu); |
7a8e76a3 | 4203 | } |
c4f50183 | 4204 | EXPORT_SYMBOL_GPL(ring_buffer_reset); |
7a8e76a3 SR |
4205 | |
4206 | /** | |
4207 | * rind_buffer_empty - is the ring buffer empty? | |
4208 | * @buffer: The ring buffer to test | |
4209 | */ | |
3d4e204d | 4210 | bool ring_buffer_empty(struct ring_buffer *buffer) |
7a8e76a3 SR |
4211 | { |
4212 | struct ring_buffer_per_cpu *cpu_buffer; | |
d4788207 | 4213 | unsigned long flags; |
289a5a25 | 4214 | bool dolock; |
7a8e76a3 | 4215 | int cpu; |
d4788207 | 4216 | int ret; |
7a8e76a3 SR |
4217 | |
4218 | /* yes this is racy, but if you don't like the race, lock the buffer */ | |
4219 | for_each_buffer_cpu(buffer, cpu) { | |
4220 | cpu_buffer = buffer->buffers[cpu]; | |
8d707e8e | 4221 | local_irq_save(flags); |
289a5a25 | 4222 | dolock = rb_reader_lock(cpu_buffer); |
d4788207 | 4223 | ret = rb_per_cpu_empty(cpu_buffer); |
289a5a25 | 4224 | rb_reader_unlock(cpu_buffer, dolock); |
8d707e8e SR |
4225 | local_irq_restore(flags); |
4226 | ||
d4788207 | 4227 | if (!ret) |
3d4e204d | 4228 | return false; |
7a8e76a3 | 4229 | } |
554f786e | 4230 | |
3d4e204d | 4231 | return true; |
7a8e76a3 | 4232 | } |
c4f50183 | 4233 | EXPORT_SYMBOL_GPL(ring_buffer_empty); |
7a8e76a3 SR |
4234 | |
4235 | /** | |
4236 | * ring_buffer_empty_cpu - is a cpu buffer of a ring buffer empty? | |
4237 | * @buffer: The ring buffer | |
4238 | * @cpu: The CPU buffer to test | |
4239 | */ | |
3d4e204d | 4240 | bool ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) |
7a8e76a3 SR |
4241 | { |
4242 | struct ring_buffer_per_cpu *cpu_buffer; | |
d4788207 | 4243 | unsigned long flags; |
289a5a25 | 4244 | bool dolock; |
8aabee57 | 4245 | int ret; |
7a8e76a3 | 4246 | |
9e01c1b7 | 4247 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
3d4e204d | 4248 | return true; |
7a8e76a3 SR |
4249 | |
4250 | cpu_buffer = buffer->buffers[cpu]; | |
8d707e8e | 4251 | local_irq_save(flags); |
289a5a25 | 4252 | dolock = rb_reader_lock(cpu_buffer); |
554f786e | 4253 | ret = rb_per_cpu_empty(cpu_buffer); |
289a5a25 | 4254 | rb_reader_unlock(cpu_buffer, dolock); |
8d707e8e | 4255 | local_irq_restore(flags); |
554f786e SR |
4256 | |
4257 | return ret; | |
7a8e76a3 | 4258 | } |
c4f50183 | 4259 | EXPORT_SYMBOL_GPL(ring_buffer_empty_cpu); |
7a8e76a3 | 4260 | |
85bac32c | 4261 | #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP |
7a8e76a3 SR |
4262 | /** |
4263 | * ring_buffer_swap_cpu - swap a CPU buffer between two ring buffers | |
4264 | * @buffer_a: One buffer to swap with | |
4265 | * @buffer_b: The other buffer to swap with | |
4266 | * | |
4267 | * This function is useful for tracers that want to take a "snapshot" | |
4268 | * of a CPU buffer and has another back up buffer lying around. | |
4269 | * it is expected that the tracer handles the cpu buffer not being | |
4270 | * used at the moment. | |
4271 | */ | |
4272 | int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, | |
4273 | struct ring_buffer *buffer_b, int cpu) | |
4274 | { | |
4275 | struct ring_buffer_per_cpu *cpu_buffer_a; | |
4276 | struct ring_buffer_per_cpu *cpu_buffer_b; | |
554f786e SR |
4277 | int ret = -EINVAL; |
4278 | ||
9e01c1b7 RR |
4279 | if (!cpumask_test_cpu(cpu, buffer_a->cpumask) || |
4280 | !cpumask_test_cpu(cpu, buffer_b->cpumask)) | |
554f786e | 4281 | goto out; |
7a8e76a3 | 4282 | |
438ced17 VN |
4283 | cpu_buffer_a = buffer_a->buffers[cpu]; |
4284 | cpu_buffer_b = buffer_b->buffers[cpu]; | |
4285 | ||
7a8e76a3 | 4286 | /* At least make sure the two buffers are somewhat the same */ |
438ced17 | 4287 | if (cpu_buffer_a->nr_pages != cpu_buffer_b->nr_pages) |
554f786e SR |
4288 | goto out; |
4289 | ||
4290 | ret = -EAGAIN; | |
7a8e76a3 | 4291 | |
97b17efe | 4292 | if (atomic_read(&buffer_a->record_disabled)) |
554f786e | 4293 | goto out; |
97b17efe SR |
4294 | |
4295 | if (atomic_read(&buffer_b->record_disabled)) | |
554f786e | 4296 | goto out; |
97b17efe | 4297 | |
97b17efe | 4298 | if (atomic_read(&cpu_buffer_a->record_disabled)) |
554f786e | 4299 | goto out; |
97b17efe SR |
4300 | |
4301 | if (atomic_read(&cpu_buffer_b->record_disabled)) | |
554f786e | 4302 | goto out; |
97b17efe | 4303 | |
7a8e76a3 SR |
4304 | /* |
4305 | * We can't do a synchronize_sched here because this | |
4306 | * function can be called in atomic context. | |
4307 | * Normally this will be called from the same CPU as cpu. | |
4308 | * If not it's up to the caller to protect this. | |
4309 | */ | |
4310 | atomic_inc(&cpu_buffer_a->record_disabled); | |
4311 | atomic_inc(&cpu_buffer_b->record_disabled); | |
4312 | ||
98277991 SR |
4313 | ret = -EBUSY; |
4314 | if (local_read(&cpu_buffer_a->committing)) | |
4315 | goto out_dec; | |
4316 | if (local_read(&cpu_buffer_b->committing)) | |
4317 | goto out_dec; | |
4318 | ||
7a8e76a3 SR |
4319 | buffer_a->buffers[cpu] = cpu_buffer_b; |
4320 | buffer_b->buffers[cpu] = cpu_buffer_a; | |
4321 | ||
4322 | cpu_buffer_b->buffer = buffer_a; | |
4323 | cpu_buffer_a->buffer = buffer_b; | |
4324 | ||
98277991 SR |
4325 | ret = 0; |
4326 | ||
4327 | out_dec: | |
7a8e76a3 SR |
4328 | atomic_dec(&cpu_buffer_a->record_disabled); |
4329 | atomic_dec(&cpu_buffer_b->record_disabled); | |
554f786e | 4330 | out: |
554f786e | 4331 | return ret; |
7a8e76a3 | 4332 | } |
c4f50183 | 4333 | EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu); |
85bac32c | 4334 | #endif /* CONFIG_RING_BUFFER_ALLOW_SWAP */ |
7a8e76a3 | 4335 | |
8789a9e7 SR |
4336 | /** |
4337 | * ring_buffer_alloc_read_page - allocate a page to read from buffer | |
4338 | * @buffer: the buffer to allocate for. | |
d611851b | 4339 | * @cpu: the cpu buffer to allocate. |
8789a9e7 SR |
4340 | * |
4341 | * This function is used in conjunction with ring_buffer_read_page. | |
4342 | * When reading a full page from the ring buffer, these functions | |
4343 | * can be used to speed up the process. The calling function should | |
4344 | * allocate a few pages first with this function. Then when it | |
4345 | * needs to get pages from the ring buffer, it passes the result | |
4346 | * of this function into ring_buffer_read_page, which will swap | |
4347 | * the page that was allocated, with the read page of the buffer. | |
4348 | * | |
4349 | * Returns: | |
a7e52ad7 | 4350 | * The page allocated, or ERR_PTR |
8789a9e7 | 4351 | */ |
7ea59064 | 4352 | void *ring_buffer_alloc_read_page(struct ring_buffer *buffer, int cpu) |
8789a9e7 | 4353 | { |
a7e52ad7 | 4354 | struct ring_buffer_per_cpu *cpu_buffer; |
73a757e6 SRV |
4355 | struct buffer_data_page *bpage = NULL; |
4356 | unsigned long flags; | |
7ea59064 | 4357 | struct page *page; |
8789a9e7 | 4358 | |
a7e52ad7 SRV |
4359 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
4360 | return ERR_PTR(-ENODEV); | |
4361 | ||
4362 | cpu_buffer = buffer->buffers[cpu]; | |
73a757e6 SRV |
4363 | local_irq_save(flags); |
4364 | arch_spin_lock(&cpu_buffer->lock); | |
4365 | ||
4366 | if (cpu_buffer->free_page) { | |
4367 | bpage = cpu_buffer->free_page; | |
4368 | cpu_buffer->free_page = NULL; | |
4369 | } | |
4370 | ||
4371 | arch_spin_unlock(&cpu_buffer->lock); | |
4372 | local_irq_restore(flags); | |
4373 | ||
4374 | if (bpage) | |
4375 | goto out; | |
4376 | ||
d7ec4bfe VN |
4377 | page = alloc_pages_node(cpu_to_node(cpu), |
4378 | GFP_KERNEL | __GFP_NORETRY, 0); | |
7ea59064 | 4379 | if (!page) |
a7e52ad7 | 4380 | return ERR_PTR(-ENOMEM); |
8789a9e7 | 4381 | |
7ea59064 | 4382 | bpage = page_address(page); |
8789a9e7 | 4383 | |
73a757e6 | 4384 | out: |
ef7a4a16 SR |
4385 | rb_init_page(bpage); |
4386 | ||
044fa782 | 4387 | return bpage; |
8789a9e7 | 4388 | } |
d6ce96da | 4389 | EXPORT_SYMBOL_GPL(ring_buffer_alloc_read_page); |
8789a9e7 SR |
4390 | |
4391 | /** | |
4392 | * ring_buffer_free_read_page - free an allocated read page | |
4393 | * @buffer: the buffer the page was allocate for | |
73a757e6 | 4394 | * @cpu: the cpu buffer the page came from |
8789a9e7 SR |
4395 | * @data: the page to free |
4396 | * | |
4397 | * Free a page allocated from ring_buffer_alloc_read_page. | |
4398 | */ | |
73a757e6 | 4399 | void ring_buffer_free_read_page(struct ring_buffer *buffer, int cpu, void *data) |
8789a9e7 | 4400 | { |
73a757e6 SRV |
4401 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; |
4402 | struct buffer_data_page *bpage = data; | |
4403 | unsigned long flags; | |
4404 | ||
4405 | local_irq_save(flags); | |
4406 | arch_spin_lock(&cpu_buffer->lock); | |
4407 | ||
4408 | if (!cpu_buffer->free_page) { | |
4409 | cpu_buffer->free_page = bpage; | |
4410 | bpage = NULL; | |
4411 | } | |
4412 | ||
4413 | arch_spin_unlock(&cpu_buffer->lock); | |
4414 | local_irq_restore(flags); | |
4415 | ||
4416 | free_page((unsigned long)bpage); | |
8789a9e7 | 4417 | } |
d6ce96da | 4418 | EXPORT_SYMBOL_GPL(ring_buffer_free_read_page); |
8789a9e7 SR |
4419 | |
4420 | /** | |
4421 | * ring_buffer_read_page - extract a page from the ring buffer | |
4422 | * @buffer: buffer to extract from | |
4423 | * @data_page: the page to use allocated from ring_buffer_alloc_read_page | |
ef7a4a16 | 4424 | * @len: amount to extract |
8789a9e7 SR |
4425 | * @cpu: the cpu of the buffer to extract |
4426 | * @full: should the extraction only happen when the page is full. | |
4427 | * | |
4428 | * This function will pull out a page from the ring buffer and consume it. | |
4429 | * @data_page must be the address of the variable that was returned | |
4430 | * from ring_buffer_alloc_read_page. This is because the page might be used | |
4431 | * to swap with a page in the ring buffer. | |
4432 | * | |
4433 | * for example: | |
d611851b | 4434 | * rpage = ring_buffer_alloc_read_page(buffer, cpu); |
a7e52ad7 SRV |
4435 | * if (IS_ERR(rpage)) |
4436 | * return PTR_ERR(rpage); | |
ef7a4a16 | 4437 | * ret = ring_buffer_read_page(buffer, &rpage, len, cpu, 0); |
667d2412 LJ |
4438 | * if (ret >= 0) |
4439 | * process_page(rpage, ret); | |
8789a9e7 SR |
4440 | * |
4441 | * When @full is set, the function will not return true unless | |
4442 | * the writer is off the reader page. | |
4443 | * | |
4444 | * Note: it is up to the calling functions to handle sleeps and wakeups. | |
4445 | * The ring buffer can be used anywhere in the kernel and can not | |
4446 | * blindly call wake_up. The layer that uses the ring buffer must be | |
4447 | * responsible for that. | |
4448 | * | |
4449 | * Returns: | |
667d2412 LJ |
4450 | * >=0 if data has been transferred, returns the offset of consumed data. |
4451 | * <0 if no data has been transferred. | |
8789a9e7 SR |
4452 | */ |
4453 | int ring_buffer_read_page(struct ring_buffer *buffer, | |
ef7a4a16 | 4454 | void **data_page, size_t len, int cpu, int full) |
8789a9e7 SR |
4455 | { |
4456 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
4457 | struct ring_buffer_event *event; | |
044fa782 | 4458 | struct buffer_data_page *bpage; |
ef7a4a16 | 4459 | struct buffer_page *reader; |
ff0ff84a | 4460 | unsigned long missed_events; |
8789a9e7 | 4461 | unsigned long flags; |
ef7a4a16 | 4462 | unsigned int commit; |
667d2412 | 4463 | unsigned int read; |
4f3640f8 | 4464 | u64 save_timestamp; |
667d2412 | 4465 | int ret = -1; |
8789a9e7 | 4466 | |
554f786e SR |
4467 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
4468 | goto out; | |
4469 | ||
474d32b6 SR |
4470 | /* |
4471 | * If len is not big enough to hold the page header, then | |
4472 | * we can not copy anything. | |
4473 | */ | |
4474 | if (len <= BUF_PAGE_HDR_SIZE) | |
554f786e | 4475 | goto out; |
474d32b6 SR |
4476 | |
4477 | len -= BUF_PAGE_HDR_SIZE; | |
4478 | ||
8789a9e7 | 4479 | if (!data_page) |
554f786e | 4480 | goto out; |
8789a9e7 | 4481 | |
044fa782 SR |
4482 | bpage = *data_page; |
4483 | if (!bpage) | |
554f786e | 4484 | goto out; |
8789a9e7 | 4485 | |
5389f6fa | 4486 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
8789a9e7 | 4487 | |
ef7a4a16 SR |
4488 | reader = rb_get_reader_page(cpu_buffer); |
4489 | if (!reader) | |
554f786e | 4490 | goto out_unlock; |
8789a9e7 | 4491 | |
ef7a4a16 SR |
4492 | event = rb_reader_event(cpu_buffer); |
4493 | ||
4494 | read = reader->read; | |
4495 | commit = rb_page_commit(reader); | |
667d2412 | 4496 | |
66a8cb95 | 4497 | /* Check if any events were dropped */ |
ff0ff84a | 4498 | missed_events = cpu_buffer->lost_events; |
66a8cb95 | 4499 | |
8789a9e7 | 4500 | /* |
474d32b6 SR |
4501 | * If this page has been partially read or |
4502 | * if len is not big enough to read the rest of the page or | |
4503 | * a writer is still on the page, then | |
4504 | * we must copy the data from the page to the buffer. | |
4505 | * Otherwise, we can simply swap the page with the one passed in. | |
8789a9e7 | 4506 | */ |
474d32b6 | 4507 | if (read || (len < (commit - read)) || |
ef7a4a16 | 4508 | cpu_buffer->reader_page == cpu_buffer->commit_page) { |
667d2412 | 4509 | struct buffer_data_page *rpage = cpu_buffer->reader_page->page; |
474d32b6 SR |
4510 | unsigned int rpos = read; |
4511 | unsigned int pos = 0; | |
ef7a4a16 | 4512 | unsigned int size; |
8789a9e7 SR |
4513 | |
4514 | if (full) | |
554f786e | 4515 | goto out_unlock; |
8789a9e7 | 4516 | |
ef7a4a16 SR |
4517 | if (len > (commit - read)) |
4518 | len = (commit - read); | |
4519 | ||
69d1b839 SR |
4520 | /* Always keep the time extend and data together */ |
4521 | size = rb_event_ts_length(event); | |
ef7a4a16 SR |
4522 | |
4523 | if (len < size) | |
554f786e | 4524 | goto out_unlock; |
ef7a4a16 | 4525 | |
4f3640f8 SR |
4526 | /* save the current timestamp, since the user will need it */ |
4527 | save_timestamp = cpu_buffer->read_stamp; | |
4528 | ||
ef7a4a16 SR |
4529 | /* Need to copy one event at a time */ |
4530 | do { | |
e1e35927 DS |
4531 | /* We need the size of one event, because |
4532 | * rb_advance_reader only advances by one event, | |
4533 | * whereas rb_event_ts_length may include the size of | |
4534 | * one or two events. | |
4535 | * We have already ensured there's enough space if this | |
4536 | * is a time extend. */ | |
4537 | size = rb_event_length(event); | |
474d32b6 | 4538 | memcpy(bpage->data + pos, rpage->data + rpos, size); |
ef7a4a16 SR |
4539 | |
4540 | len -= size; | |
4541 | ||
4542 | rb_advance_reader(cpu_buffer); | |
474d32b6 SR |
4543 | rpos = reader->read; |
4544 | pos += size; | |
ef7a4a16 | 4545 | |
18fab912 HY |
4546 | if (rpos >= commit) |
4547 | break; | |
4548 | ||
ef7a4a16 | 4549 | event = rb_reader_event(cpu_buffer); |
69d1b839 SR |
4550 | /* Always keep the time extend and data together */ |
4551 | size = rb_event_ts_length(event); | |
e1e35927 | 4552 | } while (len >= size); |
667d2412 LJ |
4553 | |
4554 | /* update bpage */ | |
ef7a4a16 | 4555 | local_set(&bpage->commit, pos); |
4f3640f8 | 4556 | bpage->time_stamp = save_timestamp; |
ef7a4a16 | 4557 | |
474d32b6 SR |
4558 | /* we copied everything to the beginning */ |
4559 | read = 0; | |
8789a9e7 | 4560 | } else { |
afbab76a | 4561 | /* update the entry counter */ |
77ae365e | 4562 | cpu_buffer->read += rb_page_entries(reader); |
c64e148a | 4563 | cpu_buffer->read_bytes += BUF_PAGE_SIZE; |
afbab76a | 4564 | |
8789a9e7 | 4565 | /* swap the pages */ |
044fa782 | 4566 | rb_init_page(bpage); |
ef7a4a16 SR |
4567 | bpage = reader->page; |
4568 | reader->page = *data_page; | |
4569 | local_set(&reader->write, 0); | |
778c55d4 | 4570 | local_set(&reader->entries, 0); |
ef7a4a16 | 4571 | reader->read = 0; |
044fa782 | 4572 | *data_page = bpage; |
ff0ff84a SR |
4573 | |
4574 | /* | |
4575 | * Use the real_end for the data size, | |
4576 | * This gives us a chance to store the lost events | |
4577 | * on the page. | |
4578 | */ | |
4579 | if (reader->real_end) | |
4580 | local_set(&bpage->commit, reader->real_end); | |
8789a9e7 | 4581 | } |
667d2412 | 4582 | ret = read; |
8789a9e7 | 4583 | |
66a8cb95 | 4584 | cpu_buffer->lost_events = 0; |
2711ca23 SR |
4585 | |
4586 | commit = local_read(&bpage->commit); | |
66a8cb95 SR |
4587 | /* |
4588 | * Set a flag in the commit field if we lost events | |
4589 | */ | |
ff0ff84a | 4590 | if (missed_events) { |
ff0ff84a SR |
4591 | /* If there is room at the end of the page to save the |
4592 | * missed events, then record it there. | |
4593 | */ | |
4594 | if (BUF_PAGE_SIZE - commit >= sizeof(missed_events)) { | |
4595 | memcpy(&bpage->data[commit], &missed_events, | |
4596 | sizeof(missed_events)); | |
4597 | local_add(RB_MISSED_STORED, &bpage->commit); | |
2711ca23 | 4598 | commit += sizeof(missed_events); |
ff0ff84a | 4599 | } |
66a8cb95 | 4600 | local_add(RB_MISSED_EVENTS, &bpage->commit); |
ff0ff84a | 4601 | } |
66a8cb95 | 4602 | |
2711ca23 SR |
4603 | /* |
4604 | * This page may be off to user land. Zero it out here. | |
4605 | */ | |
4606 | if (commit < BUF_PAGE_SIZE) | |
4607 | memset(&bpage->data[commit], 0, BUF_PAGE_SIZE - commit); | |
4608 | ||
554f786e | 4609 | out_unlock: |
5389f6fa | 4610 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
8789a9e7 | 4611 | |
554f786e | 4612 | out: |
8789a9e7 SR |
4613 | return ret; |
4614 | } | |
d6ce96da | 4615 | EXPORT_SYMBOL_GPL(ring_buffer_read_page); |
8789a9e7 | 4616 | |
b32614c0 SAS |
4617 | /* |
4618 | * We only allocate new buffers, never free them if the CPU goes down. | |
4619 | * If we were to free the buffer, then the user would lose any trace that was in | |
4620 | * the buffer. | |
4621 | */ | |
4622 | int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node) | |
554f786e | 4623 | { |
b32614c0 | 4624 | struct ring_buffer *buffer; |
9b94a8fb SRRH |
4625 | long nr_pages_same; |
4626 | int cpu_i; | |
4627 | unsigned long nr_pages; | |
554f786e | 4628 | |
b32614c0 SAS |
4629 | buffer = container_of(node, struct ring_buffer, node); |
4630 | if (cpumask_test_cpu(cpu, buffer->cpumask)) | |
4631 | return 0; | |
4632 | ||
4633 | nr_pages = 0; | |
4634 | nr_pages_same = 1; | |
4635 | /* check if all cpu sizes are same */ | |
4636 | for_each_buffer_cpu(buffer, cpu_i) { | |
4637 | /* fill in the size from first enabled cpu */ | |
4638 | if (nr_pages == 0) | |
4639 | nr_pages = buffer->buffers[cpu_i]->nr_pages; | |
4640 | if (nr_pages != buffer->buffers[cpu_i]->nr_pages) { | |
4641 | nr_pages_same = 0; | |
4642 | break; | |
554f786e | 4643 | } |
554f786e | 4644 | } |
b32614c0 SAS |
4645 | /* allocate minimum pages, user can later expand it */ |
4646 | if (!nr_pages_same) | |
4647 | nr_pages = 2; | |
4648 | buffer->buffers[cpu] = | |
4649 | rb_allocate_cpu_buffer(buffer, nr_pages, cpu); | |
4650 | if (!buffer->buffers[cpu]) { | |
4651 | WARN(1, "failed to allocate ring buffer on CPU %u\n", | |
4652 | cpu); | |
4653 | return -ENOMEM; | |
4654 | } | |
4655 | smp_wmb(); | |
4656 | cpumask_set_cpu(cpu, buffer->cpumask); | |
4657 | return 0; | |
554f786e | 4658 | } |
6c43e554 SRRH |
4659 | |
4660 | #ifdef CONFIG_RING_BUFFER_STARTUP_TEST | |
4661 | /* | |
4662 | * This is a basic integrity check of the ring buffer. | |
4663 | * Late in the boot cycle this test will run when configured in. | |
4664 | * It will kick off a thread per CPU that will go into a loop | |
4665 | * writing to the per cpu ring buffer various sizes of data. | |
4666 | * Some of the data will be large items, some small. | |
4667 | * | |
4668 | * Another thread is created that goes into a spin, sending out | |
4669 | * IPIs to the other CPUs to also write into the ring buffer. | |
4670 | * this is to test the nesting ability of the buffer. | |
4671 | * | |
4672 | * Basic stats are recorded and reported. If something in the | |
4673 | * ring buffer should happen that's not expected, a big warning | |
4674 | * is displayed and all ring buffers are disabled. | |
4675 | */ | |
4676 | static struct task_struct *rb_threads[NR_CPUS] __initdata; | |
4677 | ||
4678 | struct rb_test_data { | |
4679 | struct ring_buffer *buffer; | |
4680 | unsigned long events; | |
4681 | unsigned long bytes_written; | |
4682 | unsigned long bytes_alloc; | |
4683 | unsigned long bytes_dropped; | |
4684 | unsigned long events_nested; | |
4685 | unsigned long bytes_written_nested; | |
4686 | unsigned long bytes_alloc_nested; | |
4687 | unsigned long bytes_dropped_nested; | |
4688 | int min_size_nested; | |
4689 | int max_size_nested; | |
4690 | int max_size; | |
4691 | int min_size; | |
4692 | int cpu; | |
4693 | int cnt; | |
4694 | }; | |
4695 | ||
4696 | static struct rb_test_data rb_data[NR_CPUS] __initdata; | |
4697 | ||
4698 | /* 1 meg per cpu */ | |
4699 | #define RB_TEST_BUFFER_SIZE 1048576 | |
4700 | ||
4701 | static char rb_string[] __initdata = | |
4702 | "abcdefghijklmnopqrstuvwxyz1234567890!@#$%^&*()?+\\" | |
4703 | "?+|:';\",.<>/?abcdefghijklmnopqrstuvwxyz1234567890" | |
4704 | "!@#$%^&*()?+\\?+|:';\",.<>/?abcdefghijklmnopqrstuv"; | |
4705 | ||
4706 | static bool rb_test_started __initdata; | |
4707 | ||
4708 | struct rb_item { | |
4709 | int size; | |
4710 | char str[]; | |
4711 | }; | |
4712 | ||
4713 | static __init int rb_write_something(struct rb_test_data *data, bool nested) | |
4714 | { | |
4715 | struct ring_buffer_event *event; | |
4716 | struct rb_item *item; | |
4717 | bool started; | |
4718 | int event_len; | |
4719 | int size; | |
4720 | int len; | |
4721 | int cnt; | |
4722 | ||
4723 | /* Have nested writes different that what is written */ | |
4724 | cnt = data->cnt + (nested ? 27 : 0); | |
4725 | ||
4726 | /* Multiply cnt by ~e, to make some unique increment */ | |
4727 | size = (data->cnt * 68 / 25) % (sizeof(rb_string) - 1); | |
4728 | ||
4729 | len = size + sizeof(struct rb_item); | |
4730 | ||
4731 | started = rb_test_started; | |
4732 | /* read rb_test_started before checking buffer enabled */ | |
4733 | smp_rmb(); | |
4734 | ||
4735 | event = ring_buffer_lock_reserve(data->buffer, len); | |
4736 | if (!event) { | |
4737 | /* Ignore dropped events before test starts. */ | |
4738 | if (started) { | |
4739 | if (nested) | |
4740 | data->bytes_dropped += len; | |
4741 | else | |
4742 | data->bytes_dropped_nested += len; | |
4743 | } | |
4744 | return len; | |
4745 | } | |
4746 | ||
4747 | event_len = ring_buffer_event_length(event); | |
4748 | ||
4749 | if (RB_WARN_ON(data->buffer, event_len < len)) | |
4750 | goto out; | |
4751 | ||
4752 | item = ring_buffer_event_data(event); | |
4753 | item->size = size; | |
4754 | memcpy(item->str, rb_string, size); | |
4755 | ||
4756 | if (nested) { | |
4757 | data->bytes_alloc_nested += event_len; | |
4758 | data->bytes_written_nested += len; | |
4759 | data->events_nested++; | |
4760 | if (!data->min_size_nested || len < data->min_size_nested) | |
4761 | data->min_size_nested = len; | |
4762 | if (len > data->max_size_nested) | |
4763 | data->max_size_nested = len; | |
4764 | } else { | |
4765 | data->bytes_alloc += event_len; | |
4766 | data->bytes_written += len; | |
4767 | data->events++; | |
4768 | if (!data->min_size || len < data->min_size) | |
4769 | data->max_size = len; | |
4770 | if (len > data->max_size) | |
4771 | data->max_size = len; | |
4772 | } | |
4773 | ||
4774 | out: | |
4775 | ring_buffer_unlock_commit(data->buffer, event); | |
4776 | ||
4777 | return 0; | |
4778 | } | |
4779 | ||
4780 | static __init int rb_test(void *arg) | |
4781 | { | |
4782 | struct rb_test_data *data = arg; | |
4783 | ||
4784 | while (!kthread_should_stop()) { | |
4785 | rb_write_something(data, false); | |
4786 | data->cnt++; | |
4787 | ||
4788 | set_current_state(TASK_INTERRUPTIBLE); | |
4789 | /* Now sleep between a min of 100-300us and a max of 1ms */ | |
4790 | usleep_range(((data->cnt % 3) + 1) * 100, 1000); | |
4791 | } | |
4792 | ||
4793 | return 0; | |
4794 | } | |
4795 | ||
4796 | static __init void rb_ipi(void *ignore) | |
4797 | { | |
4798 | struct rb_test_data *data; | |
4799 | int cpu = smp_processor_id(); | |
4800 | ||
4801 | data = &rb_data[cpu]; | |
4802 | rb_write_something(data, true); | |
4803 | } | |
4804 | ||
4805 | static __init int rb_hammer_test(void *arg) | |
4806 | { | |
4807 | while (!kthread_should_stop()) { | |
4808 | ||
4809 | /* Send an IPI to all cpus to write data! */ | |
4810 | smp_call_function(rb_ipi, NULL, 1); | |
4811 | /* No sleep, but for non preempt, let others run */ | |
4812 | schedule(); | |
4813 | } | |
4814 | ||
4815 | return 0; | |
4816 | } | |
4817 | ||
4818 | static __init int test_ringbuffer(void) | |
4819 | { | |
4820 | struct task_struct *rb_hammer; | |
4821 | struct ring_buffer *buffer; | |
4822 | int cpu; | |
4823 | int ret = 0; | |
4824 | ||
4825 | pr_info("Running ring buffer tests...\n"); | |
4826 | ||
4827 | buffer = ring_buffer_alloc(RB_TEST_BUFFER_SIZE, RB_FL_OVERWRITE); | |
4828 | if (WARN_ON(!buffer)) | |
4829 | return 0; | |
4830 | ||
4831 | /* Disable buffer so that threads can't write to it yet */ | |
4832 | ring_buffer_record_off(buffer); | |
4833 | ||
4834 | for_each_online_cpu(cpu) { | |
4835 | rb_data[cpu].buffer = buffer; | |
4836 | rb_data[cpu].cpu = cpu; | |
4837 | rb_data[cpu].cnt = cpu; | |
4838 | rb_threads[cpu] = kthread_create(rb_test, &rb_data[cpu], | |
4839 | "rbtester/%d", cpu); | |
62277de7 | 4840 | if (WARN_ON(IS_ERR(rb_threads[cpu]))) { |
6c43e554 | 4841 | pr_cont("FAILED\n"); |
62277de7 | 4842 | ret = PTR_ERR(rb_threads[cpu]); |
6c43e554 SRRH |
4843 | goto out_free; |
4844 | } | |
4845 | ||
4846 | kthread_bind(rb_threads[cpu], cpu); | |
4847 | wake_up_process(rb_threads[cpu]); | |
4848 | } | |
4849 | ||
4850 | /* Now create the rb hammer! */ | |
4851 | rb_hammer = kthread_run(rb_hammer_test, NULL, "rbhammer"); | |
62277de7 | 4852 | if (WARN_ON(IS_ERR(rb_hammer))) { |
6c43e554 | 4853 | pr_cont("FAILED\n"); |
62277de7 | 4854 | ret = PTR_ERR(rb_hammer); |
6c43e554 SRRH |
4855 | goto out_free; |
4856 | } | |
4857 | ||
4858 | ring_buffer_record_on(buffer); | |
4859 | /* | |
4860 | * Show buffer is enabled before setting rb_test_started. | |
4861 | * Yes there's a small race window where events could be | |
4862 | * dropped and the thread wont catch it. But when a ring | |
4863 | * buffer gets enabled, there will always be some kind of | |
4864 | * delay before other CPUs see it. Thus, we don't care about | |
4865 | * those dropped events. We care about events dropped after | |
4866 | * the threads see that the buffer is active. | |
4867 | */ | |
4868 | smp_wmb(); | |
4869 | rb_test_started = true; | |
4870 | ||
4871 | set_current_state(TASK_INTERRUPTIBLE); | |
4872 | /* Just run for 10 seconds */; | |
4873 | schedule_timeout(10 * HZ); | |
4874 | ||
4875 | kthread_stop(rb_hammer); | |
4876 | ||
4877 | out_free: | |
4878 | for_each_online_cpu(cpu) { | |
4879 | if (!rb_threads[cpu]) | |
4880 | break; | |
4881 | kthread_stop(rb_threads[cpu]); | |
4882 | } | |
4883 | if (ret) { | |
4884 | ring_buffer_free(buffer); | |
4885 | return ret; | |
4886 | } | |
4887 | ||
4888 | /* Report! */ | |
4889 | pr_info("finished\n"); | |
4890 | for_each_online_cpu(cpu) { | |
4891 | struct ring_buffer_event *event; | |
4892 | struct rb_test_data *data = &rb_data[cpu]; | |
4893 | struct rb_item *item; | |
4894 | unsigned long total_events; | |
4895 | unsigned long total_dropped; | |
4896 | unsigned long total_written; | |
4897 | unsigned long total_alloc; | |
4898 | unsigned long total_read = 0; | |
4899 | unsigned long total_size = 0; | |
4900 | unsigned long total_len = 0; | |
4901 | unsigned long total_lost = 0; | |
4902 | unsigned long lost; | |
4903 | int big_event_size; | |
4904 | int small_event_size; | |
4905 | ||
4906 | ret = -1; | |
4907 | ||
4908 | total_events = data->events + data->events_nested; | |
4909 | total_written = data->bytes_written + data->bytes_written_nested; | |
4910 | total_alloc = data->bytes_alloc + data->bytes_alloc_nested; | |
4911 | total_dropped = data->bytes_dropped + data->bytes_dropped_nested; | |
4912 | ||
4913 | big_event_size = data->max_size + data->max_size_nested; | |
4914 | small_event_size = data->min_size + data->min_size_nested; | |
4915 | ||
4916 | pr_info("CPU %d:\n", cpu); | |
4917 | pr_info(" events: %ld\n", total_events); | |
4918 | pr_info(" dropped bytes: %ld\n", total_dropped); | |
4919 | pr_info(" alloced bytes: %ld\n", total_alloc); | |
4920 | pr_info(" written bytes: %ld\n", total_written); | |
4921 | pr_info(" biggest event: %d\n", big_event_size); | |
4922 | pr_info(" smallest event: %d\n", small_event_size); | |
4923 | ||
4924 | if (RB_WARN_ON(buffer, total_dropped)) | |
4925 | break; | |
4926 | ||
4927 | ret = 0; | |
4928 | ||
4929 | while ((event = ring_buffer_consume(buffer, cpu, NULL, &lost))) { | |
4930 | total_lost += lost; | |
4931 | item = ring_buffer_event_data(event); | |
4932 | total_len += ring_buffer_event_length(event); | |
4933 | total_size += item->size + sizeof(struct rb_item); | |
4934 | if (memcmp(&item->str[0], rb_string, item->size) != 0) { | |
4935 | pr_info("FAILED!\n"); | |
4936 | pr_info("buffer had: %.*s\n", item->size, item->str); | |
4937 | pr_info("expected: %.*s\n", item->size, rb_string); | |
4938 | RB_WARN_ON(buffer, 1); | |
4939 | ret = -1; | |
4940 | break; | |
4941 | } | |
4942 | total_read++; | |
4943 | } | |
4944 | if (ret) | |
4945 | break; | |
4946 | ||
4947 | ret = -1; | |
4948 | ||
4949 | pr_info(" read events: %ld\n", total_read); | |
4950 | pr_info(" lost events: %ld\n", total_lost); | |
4951 | pr_info(" total events: %ld\n", total_lost + total_read); | |
4952 | pr_info(" recorded len bytes: %ld\n", total_len); | |
4953 | pr_info(" recorded size bytes: %ld\n", total_size); | |
4954 | if (total_lost) | |
4955 | pr_info(" With dropped events, record len and size may not match\n" | |
4956 | " alloced and written from above\n"); | |
4957 | if (!total_lost) { | |
4958 | if (RB_WARN_ON(buffer, total_len != total_alloc || | |
4959 | total_size != total_written)) | |
4960 | break; | |
4961 | } | |
4962 | if (RB_WARN_ON(buffer, total_lost + total_read != total_events)) | |
4963 | break; | |
4964 | ||
4965 | ret = 0; | |
4966 | } | |
4967 | if (!ret) | |
4968 | pr_info("Ring buffer PASSED!\n"); | |
4969 | ||
4970 | ring_buffer_free(buffer); | |
4971 | return 0; | |
4972 | } | |
4973 | ||
4974 | late_initcall(test_ringbuffer); | |
4975 | #endif /* CONFIG_RING_BUFFER_STARTUP_TEST */ |