Commit | Line | Data |
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bcea3f96 | 1 | // SPDX-License-Identifier: GPL-2.0 |
7a8e76a3 SR |
2 | /* |
3 | * Generic ring buffer | |
4 | * | |
5 | * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com> | |
6 | */ | |
28575c61 | 7 | #include <linux/trace_recursion.h> |
af658dca | 8 | #include <linux/trace_events.h> |
7a8e76a3 | 9 | #include <linux/ring_buffer.h> |
14131f2f | 10 | #include <linux/trace_clock.h> |
e6017571 | 11 | #include <linux/sched/clock.h> |
117c3920 | 12 | #include <linux/cacheflush.h> |
0b07436d | 13 | #include <linux/trace_seq.h> |
7a8e76a3 | 14 | #include <linux/spinlock.h> |
15693458 | 15 | #include <linux/irq_work.h> |
a356646a | 16 | #include <linux/security.h> |
7a8e76a3 | 17 | #include <linux/uaccess.h> |
a81bd80a | 18 | #include <linux/hardirq.h> |
6c43e554 | 19 | #include <linux/kthread.h> /* for self test */ |
7a8e76a3 SR |
20 | #include <linux/module.h> |
21 | #include <linux/percpu.h> | |
22 | #include <linux/mutex.h> | |
6c43e554 | 23 | #include <linux/delay.h> |
5a0e3ad6 | 24 | #include <linux/slab.h> |
7a8e76a3 SR |
25 | #include <linux/init.h> |
26 | #include <linux/hash.h> | |
27 | #include <linux/list.h> | |
554f786e | 28 | #include <linux/cpu.h> |
927e56db | 29 | #include <linux/oom.h> |
117c3920 | 30 | #include <linux/mm.h> |
7a8e76a3 | 31 | |
c84897c0 | 32 | #include <asm/local64.h> |
79615760 | 33 | #include <asm/local.h> |
182e9f5f | 34 | |
6695da58 SRG |
35 | /* |
36 | * The "absolute" timestamp in the buffer is only 59 bits. | |
37 | * If a clock has the 5 MSBs set, it needs to be saved and | |
38 | * reinserted. | |
39 | */ | |
40 | #define TS_MSB (0xf8ULL << 56) | |
41 | #define ABS_TS_MASK (~TS_MSB) | |
42 | ||
83f40318 VN |
43 | static void update_pages_handler(struct work_struct *work); |
44 | ||
d1b182a8 SR |
45 | /* |
46 | * The ring buffer header is special. We must manually up keep it. | |
47 | */ | |
48 | int ring_buffer_print_entry_header(struct trace_seq *s) | |
49 | { | |
c0cd93aa SRRH |
50 | trace_seq_puts(s, "# compressed entry header\n"); |
51 | trace_seq_puts(s, "\ttype_len : 5 bits\n"); | |
52 | trace_seq_puts(s, "\ttime_delta : 27 bits\n"); | |
53 | trace_seq_puts(s, "\tarray : 32 bits\n"); | |
54 | trace_seq_putc(s, '\n'); | |
55 | trace_seq_printf(s, "\tpadding : type == %d\n", | |
56 | RINGBUF_TYPE_PADDING); | |
57 | trace_seq_printf(s, "\ttime_extend : type == %d\n", | |
58 | RINGBUF_TYPE_TIME_EXTEND); | |
dc4e2801 TZ |
59 | trace_seq_printf(s, "\ttime_stamp : type == %d\n", |
60 | RINGBUF_TYPE_TIME_STAMP); | |
c0cd93aa SRRH |
61 | trace_seq_printf(s, "\tdata max type_len == %d\n", |
62 | RINGBUF_TYPE_DATA_TYPE_LEN_MAX); | |
63 | ||
64 | return !trace_seq_has_overflowed(s); | |
d1b182a8 SR |
65 | } |
66 | ||
5cc98548 SR |
67 | /* |
68 | * The ring buffer is made up of a list of pages. A separate list of pages is | |
69 | * allocated for each CPU. A writer may only write to a buffer that is | |
70 | * associated with the CPU it is currently executing on. A reader may read | |
71 | * from any per cpu buffer. | |
72 | * | |
73 | * The reader is special. For each per cpu buffer, the reader has its own | |
74 | * reader page. When a reader has read the entire reader page, this reader | |
75 | * page is swapped with another page in the ring buffer. | |
76 | * | |
77 | * Now, as long as the writer is off the reader page, the reader can do what | |
78 | * ever it wants with that page. The writer will never write to that page | |
79 | * again (as long as it is out of the ring buffer). | |
80 | * | |
81 | * Here's some silly ASCII art. | |
82 | * | |
83 | * +------+ | |
84 | * |reader| RING BUFFER | |
85 | * |page | | |
86 | * +------+ +---+ +---+ +---+ | |
87 | * | |-->| |-->| | | |
88 | * +---+ +---+ +---+ | |
89 | * ^ | | |
90 | * | | | |
91 | * +---------------+ | |
92 | * | |
93 | * | |
94 | * +------+ | |
95 | * |reader| RING BUFFER | |
96 | * |page |------------------v | |
97 | * +------+ +---+ +---+ +---+ | |
98 | * | |-->| |-->| | | |
99 | * +---+ +---+ +---+ | |
100 | * ^ | | |
101 | * | | | |
102 | * +---------------+ | |
103 | * | |
104 | * | |
105 | * +------+ | |
106 | * |reader| RING BUFFER | |
107 | * |page |------------------v | |
108 | * +------+ +---+ +---+ +---+ | |
109 | * ^ | |-->| |-->| | | |
110 | * | +---+ +---+ +---+ | |
111 | * | | | |
112 | * | | | |
113 | * +------------------------------+ | |
114 | * | |
115 | * | |
116 | * +------+ | |
117 | * |buffer| RING BUFFER | |
118 | * |page |------------------v | |
119 | * +------+ +---+ +---+ +---+ | |
120 | * ^ | | | |-->| | | |
121 | * | New +---+ +---+ +---+ | |
122 | * | Reader------^ | | |
123 | * | page | | |
124 | * +------------------------------+ | |
125 | * | |
126 | * | |
127 | * After we make this swap, the reader can hand this page off to the splice | |
128 | * code and be done with it. It can even allocate a new page if it needs to | |
129 | * and swap that into the ring buffer. | |
130 | * | |
131 | * We will be using cmpxchg soon to make all this lockless. | |
132 | * | |
133 | */ | |
134 | ||
499e5470 SR |
135 | /* Used for individual buffers (after the counter) */ |
136 | #define RB_BUFFER_OFF (1 << 20) | |
a3583244 | 137 | |
499e5470 | 138 | #define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data) |
033601a3 | 139 | |
e3d6bf0a | 140 | #define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array)) |
67d34724 | 141 | #define RB_ALIGNMENT 4U |
334d4169 | 142 | #define RB_MAX_SMALL_DATA (RB_ALIGNMENT * RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
c7b09308 | 143 | #define RB_EVNT_MIN_SIZE 8U /* two 32bit words */ |
adab66b7 SRV |
144 | |
145 | #ifndef CONFIG_HAVE_64BIT_ALIGNED_ACCESS | |
146 | # define RB_FORCE_8BYTE_ALIGNMENT 0 | |
147 | # define RB_ARCH_ALIGNMENT RB_ALIGNMENT | |
148 | #else | |
149 | # define RB_FORCE_8BYTE_ALIGNMENT 1 | |
150 | # define RB_ARCH_ALIGNMENT 8U | |
151 | #endif | |
152 | ||
153 | #define RB_ALIGN_DATA __aligned(RB_ARCH_ALIGNMENT) | |
649508f6 | 154 | |
334d4169 LJ |
155 | /* define RINGBUF_TYPE_DATA for 'case RINGBUF_TYPE_DATA:' */ |
156 | #define RINGBUF_TYPE_DATA 0 ... RINGBUF_TYPE_DATA_TYPE_LEN_MAX | |
7a8e76a3 SR |
157 | |
158 | enum { | |
159 | RB_LEN_TIME_EXTEND = 8, | |
dc4e2801 | 160 | RB_LEN_TIME_STAMP = 8, |
7a8e76a3 SR |
161 | }; |
162 | ||
69d1b839 SR |
163 | #define skip_time_extend(event) \ |
164 | ((struct ring_buffer_event *)((char *)event + RB_LEN_TIME_EXTEND)) | |
165 | ||
dc4e2801 TZ |
166 | #define extended_time(event) \ |
167 | (event->type_len >= RINGBUF_TYPE_TIME_EXTEND) | |
168 | ||
bc92b956 | 169 | static inline bool rb_null_event(struct ring_buffer_event *event) |
2d622719 | 170 | { |
a1863c21 | 171 | return event->type_len == RINGBUF_TYPE_PADDING && !event->time_delta; |
2d622719 TZ |
172 | } |
173 | ||
174 | static void rb_event_set_padding(struct ring_buffer_event *event) | |
175 | { | |
a1863c21 | 176 | /* padding has a NULL time_delta */ |
334d4169 | 177 | event->type_len = RINGBUF_TYPE_PADDING; |
2d622719 TZ |
178 | event->time_delta = 0; |
179 | } | |
180 | ||
34a148bf | 181 | static unsigned |
2d622719 | 182 | rb_event_data_length(struct ring_buffer_event *event) |
7a8e76a3 SR |
183 | { |
184 | unsigned length; | |
185 | ||
334d4169 LJ |
186 | if (event->type_len) |
187 | length = event->type_len * RB_ALIGNMENT; | |
2d622719 TZ |
188 | else |
189 | length = event->array[0]; | |
190 | return length + RB_EVNT_HDR_SIZE; | |
191 | } | |
192 | ||
69d1b839 SR |
193 | /* |
194 | * Return the length of the given event. Will return | |
195 | * the length of the time extend if the event is a | |
196 | * time extend. | |
197 | */ | |
198 | static inline unsigned | |
2d622719 TZ |
199 | rb_event_length(struct ring_buffer_event *event) |
200 | { | |
334d4169 | 201 | switch (event->type_len) { |
7a8e76a3 | 202 | case RINGBUF_TYPE_PADDING: |
2d622719 TZ |
203 | if (rb_null_event(event)) |
204 | /* undefined */ | |
205 | return -1; | |
334d4169 | 206 | return event->array[0] + RB_EVNT_HDR_SIZE; |
7a8e76a3 SR |
207 | |
208 | case RINGBUF_TYPE_TIME_EXTEND: | |
209 | return RB_LEN_TIME_EXTEND; | |
210 | ||
211 | case RINGBUF_TYPE_TIME_STAMP: | |
212 | return RB_LEN_TIME_STAMP; | |
213 | ||
214 | case RINGBUF_TYPE_DATA: | |
2d622719 | 215 | return rb_event_data_length(event); |
7a8e76a3 | 216 | default: |
da4d401a | 217 | WARN_ON_ONCE(1); |
7a8e76a3 SR |
218 | } |
219 | /* not hit */ | |
220 | return 0; | |
221 | } | |
222 | ||
69d1b839 SR |
223 | /* |
224 | * Return total length of time extend and data, | |
225 | * or just the event length for all other events. | |
226 | */ | |
227 | static inline unsigned | |
228 | rb_event_ts_length(struct ring_buffer_event *event) | |
229 | { | |
230 | unsigned len = 0; | |
231 | ||
dc4e2801 | 232 | if (extended_time(event)) { |
69d1b839 SR |
233 | /* time extends include the data event after it */ |
234 | len = RB_LEN_TIME_EXTEND; | |
235 | event = skip_time_extend(event); | |
236 | } | |
237 | return len + rb_event_length(event); | |
238 | } | |
239 | ||
7a8e76a3 SR |
240 | /** |
241 | * ring_buffer_event_length - return the length of the event | |
242 | * @event: the event to get the length of | |
69d1b839 SR |
243 | * |
244 | * Returns the size of the data load of a data event. | |
245 | * If the event is something other than a data event, it | |
246 | * returns the size of the event itself. With the exception | |
247 | * of a TIME EXTEND, where it still returns the size of the | |
248 | * data load of the data event after it. | |
7a8e76a3 SR |
249 | */ |
250 | unsigned ring_buffer_event_length(struct ring_buffer_event *event) | |
251 | { | |
69d1b839 SR |
252 | unsigned length; |
253 | ||
dc4e2801 | 254 | if (extended_time(event)) |
69d1b839 SR |
255 | event = skip_time_extend(event); |
256 | ||
257 | length = rb_event_length(event); | |
334d4169 | 258 | if (event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
465634ad RR |
259 | return length; |
260 | length -= RB_EVNT_HDR_SIZE; | |
261 | if (length > RB_MAX_SMALL_DATA + sizeof(event->array[0])) | |
262 | length -= sizeof(event->array[0]); | |
263 | return length; | |
7a8e76a3 | 264 | } |
c4f50183 | 265 | EXPORT_SYMBOL_GPL(ring_buffer_event_length); |
7a8e76a3 SR |
266 | |
267 | /* inline for ring buffer fast paths */ | |
929ddbf3 | 268 | static __always_inline void * |
7a8e76a3 SR |
269 | rb_event_data(struct ring_buffer_event *event) |
270 | { | |
dc4e2801 | 271 | if (extended_time(event)) |
69d1b839 | 272 | event = skip_time_extend(event); |
da4d401a | 273 | WARN_ON_ONCE(event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX); |
7a8e76a3 | 274 | /* If length is in len field, then array[0] has the data */ |
334d4169 | 275 | if (event->type_len) |
7a8e76a3 SR |
276 | return (void *)&event->array[0]; |
277 | /* Otherwise length is in array[0] and array[1] has the data */ | |
278 | return (void *)&event->array[1]; | |
279 | } | |
280 | ||
281 | /** | |
282 | * ring_buffer_event_data - return the data of the event | |
283 | * @event: the event to get the data from | |
284 | */ | |
285 | void *ring_buffer_event_data(struct ring_buffer_event *event) | |
286 | { | |
287 | return rb_event_data(event); | |
288 | } | |
c4f50183 | 289 | EXPORT_SYMBOL_GPL(ring_buffer_event_data); |
7a8e76a3 SR |
290 | |
291 | #define for_each_buffer_cpu(buffer, cpu) \ | |
9e01c1b7 | 292 | for_each_cpu(cpu, buffer->cpumask) |
7a8e76a3 | 293 | |
b23d7a5f NP |
294 | #define for_each_online_buffer_cpu(buffer, cpu) \ |
295 | for_each_cpu_and(cpu, buffer->cpumask, cpu_online_mask) | |
296 | ||
7a8e76a3 SR |
297 | #define TS_SHIFT 27 |
298 | #define TS_MASK ((1ULL << TS_SHIFT) - 1) | |
299 | #define TS_DELTA_TEST (~TS_MASK) | |
300 | ||
e20044f7 SRV |
301 | static u64 rb_event_time_stamp(struct ring_buffer_event *event) |
302 | { | |
303 | u64 ts; | |
304 | ||
305 | ts = event->array[0]; | |
306 | ts <<= TS_SHIFT; | |
307 | ts += event->time_delta; | |
308 | ||
309 | return ts; | |
310 | } | |
311 | ||
66a8cb95 SR |
312 | /* Flag when events were overwritten */ |
313 | #define RB_MISSED_EVENTS (1 << 31) | |
ff0ff84a SR |
314 | /* Missed count stored at end */ |
315 | #define RB_MISSED_STORED (1 << 30) | |
66a8cb95 | 316 | |
fe832be0 SRG |
317 | #define RB_MISSED_MASK (3 << 30) |
318 | ||
abc9b56d | 319 | struct buffer_data_page { |
e4c2ce82 | 320 | u64 time_stamp; /* page time stamp */ |
c3706f00 | 321 | local_t commit; /* write committed index */ |
649508f6 | 322 | unsigned char data[] RB_ALIGN_DATA; /* data of buffer page */ |
abc9b56d SR |
323 | }; |
324 | ||
bce761d7 TSV |
325 | struct buffer_data_read_page { |
326 | unsigned order; /* order of the page */ | |
327 | struct buffer_data_page *data; /* actual data, stored in this page */ | |
328 | }; | |
329 | ||
77ae365e SR |
330 | /* |
331 | * Note, the buffer_page list must be first. The buffer pages | |
332 | * are allocated in cache lines, which means that each buffer | |
333 | * page will be at the beginning of a cache line, and thus | |
334 | * the least significant bits will be zero. We use this to | |
335 | * add flags in the list struct pointers, to make the ring buffer | |
336 | * lockless. | |
337 | */ | |
abc9b56d | 338 | struct buffer_page { |
778c55d4 | 339 | struct list_head list; /* list of buffer pages */ |
abc9b56d | 340 | local_t write; /* index for next write */ |
6f807acd | 341 | unsigned read; /* index for next read */ |
778c55d4 | 342 | local_t entries; /* entries on this page */ |
ff0ff84a | 343 | unsigned long real_end; /* real end of data */ |
f9b94daa | 344 | unsigned order; /* order of the page */ |
117c3920 | 345 | u32 id; /* ID for external mapping */ |
abc9b56d | 346 | struct buffer_data_page *page; /* Actual data page */ |
7a8e76a3 SR |
347 | }; |
348 | ||
77ae365e SR |
349 | /* |
350 | * The buffer page counters, write and entries, must be reset | |
351 | * atomically when crossing page boundaries. To synchronize this | |
352 | * update, two counters are inserted into the number. One is | |
353 | * the actual counter for the write position or count on the page. | |
354 | * | |
355 | * The other is a counter of updaters. Before an update happens | |
356 | * the update partition of the counter is incremented. This will | |
357 | * allow the updater to update the counter atomically. | |
358 | * | |
359 | * The counter is 20 bits, and the state data is 12. | |
360 | */ | |
361 | #define RB_WRITE_MASK 0xfffff | |
362 | #define RB_WRITE_INTCNT (1 << 20) | |
363 | ||
044fa782 | 364 | static void rb_init_page(struct buffer_data_page *bpage) |
abc9b56d | 365 | { |
044fa782 | 366 | local_set(&bpage->commit, 0); |
abc9b56d SR |
367 | } |
368 | ||
45d99ea4 ZY |
369 | static __always_inline unsigned int rb_page_commit(struct buffer_page *bpage) |
370 | { | |
371 | return local_read(&bpage->page->commit); | |
372 | } | |
373 | ||
34a148bf | 374 | static void free_buffer_page(struct buffer_page *bpage) |
ed56829c | 375 | { |
f9b94daa | 376 | free_pages((unsigned long)bpage->page, bpage->order); |
e4c2ce82 | 377 | kfree(bpage); |
ed56829c SR |
378 | } |
379 | ||
7a8e76a3 SR |
380 | /* |
381 | * We need to fit the time_stamp delta into 27 bits. | |
382 | */ | |
bc92b956 | 383 | static inline bool test_time_stamp(u64 delta) |
7a8e76a3 | 384 | { |
bc92b956 | 385 | return !!(delta & TS_DELTA_TEST); |
7a8e76a3 SR |
386 | } |
387 | ||
15693458 SRRH |
388 | struct rb_irq_work { |
389 | struct irq_work work; | |
390 | wait_queue_head_t waiters; | |
1e0d6714 | 391 | wait_queue_head_t full_waiters; |
b70f2938 | 392 | atomic_t seq; |
15693458 | 393 | bool waiters_pending; |
1e0d6714 SRRH |
394 | bool full_waiters_pending; |
395 | bool wakeup_full; | |
15693458 SRRH |
396 | }; |
397 | ||
fcc742ea SRRH |
398 | /* |
399 | * Structure to hold event state and handle nested events. | |
400 | */ | |
401 | struct rb_event_info { | |
402 | u64 ts; | |
403 | u64 delta; | |
58fbc3c6 SRV |
404 | u64 before; |
405 | u64 after; | |
fcc742ea SRRH |
406 | unsigned long length; |
407 | struct buffer_page *tail_page; | |
408 | int add_timestamp; | |
409 | }; | |
410 | ||
a389d86f SRV |
411 | /* |
412 | * Used for the add_timestamp | |
413 | * NONE | |
7c4b4a51 SRV |
414 | * EXTEND - wants a time extend |
415 | * ABSOLUTE - the buffer requests all events to have absolute time stamps | |
a389d86f SRV |
416 | * FORCE - force a full time stamp. |
417 | */ | |
418 | enum { | |
7c4b4a51 SRV |
419 | RB_ADD_STAMP_NONE = 0, |
420 | RB_ADD_STAMP_EXTEND = BIT(1), | |
421 | RB_ADD_STAMP_ABSOLUTE = BIT(2), | |
422 | RB_ADD_STAMP_FORCE = BIT(3) | |
a389d86f | 423 | }; |
a497adb4 SRRH |
424 | /* |
425 | * Used for which event context the event is in. | |
b02414c8 SRV |
426 | * TRANSITION = 0 |
427 | * NMI = 1 | |
428 | * IRQ = 2 | |
429 | * SOFTIRQ = 3 | |
430 | * NORMAL = 4 | |
a497adb4 SRRH |
431 | * |
432 | * See trace_recursive_lock() comment below for more details. | |
433 | */ | |
434 | enum { | |
b02414c8 | 435 | RB_CTX_TRANSITION, |
a497adb4 SRRH |
436 | RB_CTX_NMI, |
437 | RB_CTX_IRQ, | |
438 | RB_CTX_SOFTIRQ, | |
439 | RB_CTX_NORMAL, | |
440 | RB_CTX_MAX | |
441 | }; | |
442 | ||
10464b4a SRV |
443 | struct rb_time_struct { |
444 | local64_t time; | |
445 | }; | |
10464b4a SRV |
446 | typedef struct rb_time_struct rb_time_t; |
447 | ||
8672e494 SRV |
448 | #define MAX_NEST 5 |
449 | ||
7a8e76a3 SR |
450 | /* |
451 | * head_page == tail_page && head == tail then buffer is empty. | |
452 | */ | |
453 | struct ring_buffer_per_cpu { | |
454 | int cpu; | |
985023de | 455 | atomic_t record_disabled; |
07b8b10e | 456 | atomic_t resize_disabled; |
13292494 | 457 | struct trace_buffer *buffer; |
5389f6fa | 458 | raw_spinlock_t reader_lock; /* serialize readers */ |
445c8951 | 459 | arch_spinlock_t lock; |
7a8e76a3 | 460 | struct lock_class_key lock_key; |
73a757e6 | 461 | struct buffer_data_page *free_page; |
9b94a8fb | 462 | unsigned long nr_pages; |
58a09ec6 | 463 | unsigned int current_context; |
3adc54fa | 464 | struct list_head *pages; |
6f807acd SR |
465 | struct buffer_page *head_page; /* read from head */ |
466 | struct buffer_page *tail_page; /* write to tail */ | |
c3706f00 | 467 | struct buffer_page *commit_page; /* committed pages */ |
d769041f | 468 | struct buffer_page *reader_page; |
66a8cb95 SR |
469 | unsigned long lost_events; |
470 | unsigned long last_overrun; | |
8e012066 | 471 | unsigned long nest; |
c64e148a | 472 | local_t entries_bytes; |
e4906eff | 473 | local_t entries; |
884bfe89 SP |
474 | local_t overrun; |
475 | local_t commit_overrun; | |
476 | local_t dropped_events; | |
fa743953 SR |
477 | local_t committing; |
478 | local_t commits; | |
2c2b0a78 | 479 | local_t pages_touched; |
31029a8b | 480 | local_t pages_lost; |
2c2b0a78 | 481 | local_t pages_read; |
03329f99 | 482 | long last_pages_touch; |
2c2b0a78 | 483 | size_t shortest_full; |
77ae365e | 484 | unsigned long read; |
c64e148a | 485 | unsigned long read_bytes; |
10464b4a SRV |
486 | rb_time_t write_stamp; |
487 | rb_time_t before_stamp; | |
8672e494 | 488 | u64 event_stamp[MAX_NEST]; |
7a8e76a3 | 489 | u64 read_stamp; |
2d093282 ZY |
490 | /* pages removed since last reset */ |
491 | unsigned long pages_removed; | |
117c3920 VD |
492 | |
493 | unsigned int mapped; | |
494 | struct mutex mapping_lock; | |
495 | unsigned long *subbuf_ids; /* ID to subbuf VA */ | |
496 | struct trace_buffer_meta *meta_page; | |
497 | ||
438ced17 | 498 | /* ring buffer pages to update, > 0 to add, < 0 to remove */ |
9b94a8fb | 499 | long nr_pages_to_update; |
438ced17 | 500 | struct list_head new_pages; /* new pages to add */ |
83f40318 | 501 | struct work_struct update_pages_work; |
05fdd70d | 502 | struct completion update_done; |
15693458 SRRH |
503 | |
504 | struct rb_irq_work irq_work; | |
7a8e76a3 SR |
505 | }; |
506 | ||
13292494 | 507 | struct trace_buffer { |
7a8e76a3 SR |
508 | unsigned flags; |
509 | int cpus; | |
7a8e76a3 | 510 | atomic_t record_disabled; |
8a96c028 | 511 | atomic_t resizing; |
00f62f61 | 512 | cpumask_var_t cpumask; |
7a8e76a3 | 513 | |
1f8a6a10 PZ |
514 | struct lock_class_key *reader_lock_key; |
515 | ||
7a8e76a3 SR |
516 | struct mutex mutex; |
517 | ||
518 | struct ring_buffer_per_cpu **buffers; | |
554f786e | 519 | |
b32614c0 | 520 | struct hlist_node node; |
37886f6a | 521 | u64 (*clock)(void); |
15693458 SRRH |
522 | |
523 | struct rb_irq_work irq_work; | |
00b41452 | 524 | bool time_stamp_abs; |
139f8400 TSV |
525 | |
526 | unsigned int subbuf_size; | |
2808e31e | 527 | unsigned int subbuf_order; |
139f8400 | 528 | unsigned int max_data_size; |
7a8e76a3 SR |
529 | }; |
530 | ||
531 | struct ring_buffer_iter { | |
532 | struct ring_buffer_per_cpu *cpu_buffer; | |
533 | unsigned long head; | |
785888c5 | 534 | unsigned long next_event; |
7a8e76a3 | 535 | struct buffer_page *head_page; |
492a74f4 SR |
536 | struct buffer_page *cache_reader_page; |
537 | unsigned long cache_read; | |
2d093282 | 538 | unsigned long cache_pages_removed; |
7a8e76a3 | 539 | u64 read_stamp; |
28e3fc56 | 540 | u64 page_stamp; |
785888c5 | 541 | struct ring_buffer_event *event; |
139f8400 | 542 | size_t event_size; |
c9b7a4a7 | 543 | int missed_events; |
7a8e76a3 SR |
544 | }; |
545 | ||
139f8400 | 546 | int ring_buffer_print_page_header(struct trace_buffer *buffer, struct trace_seq *s) |
10464b4a | 547 | { |
d5cfbdfc | 548 | struct buffer_data_page field; |
10464b4a | 549 | |
d5cfbdfc TSV |
550 | trace_seq_printf(s, "\tfield: u64 timestamp;\t" |
551 | "offset:0;\tsize:%u;\tsigned:%u;\n", | |
552 | (unsigned int)sizeof(field.time_stamp), | |
553 | (unsigned int)is_signed_type(u64)); | |
10464b4a | 554 | |
d5cfbdfc TSV |
555 | trace_seq_printf(s, "\tfield: local_t commit;\t" |
556 | "offset:%u;\tsize:%u;\tsigned:%u;\n", | |
557 | (unsigned int)offsetof(typeof(field), commit), | |
558 | (unsigned int)sizeof(field.commit), | |
559 | (unsigned int)is_signed_type(long)); | |
10464b4a | 560 | |
d5cfbdfc TSV |
561 | trace_seq_printf(s, "\tfield: int overwrite;\t" |
562 | "offset:%u;\tsize:%u;\tsigned:%u;\n", | |
563 | (unsigned int)offsetof(typeof(field), commit), | |
564 | 1, | |
565 | (unsigned int)is_signed_type(long)); | |
10464b4a | 566 | |
d5cfbdfc TSV |
567 | trace_seq_printf(s, "\tfield: char data;\t" |
568 | "offset:%u;\tsize:%u;\tsigned:%u;\n", | |
569 | (unsigned int)offsetof(typeof(field), data), | |
139f8400 | 570 | (unsigned int)buffer->subbuf_size, |
d5cfbdfc | 571 | (unsigned int)is_signed_type(char)); |
10464b4a | 572 | |
d5cfbdfc | 573 | return !trace_seq_has_overflowed(s); |
10464b4a SRV |
574 | } |
575 | ||
c84897c0 | 576 | static inline void rb_time_read(rb_time_t *t, u64 *ret) |
10464b4a SRV |
577 | { |
578 | *ret = local64_read(&t->time); | |
10464b4a SRV |
579 | } |
580 | static void rb_time_set(rb_time_t *t, u64 val) | |
581 | { | |
582 | local64_set(&t->time, val); | |
583 | } | |
10464b4a | 584 | |
a948c69d SRV |
585 | /* |
586 | * Enable this to make sure that the event passed to | |
587 | * ring_buffer_event_time_stamp() is not committed and also | |
588 | * is on the buffer that it passed in. | |
589 | */ | |
590 | //#define RB_VERIFY_EVENT | |
591 | #ifdef RB_VERIFY_EVENT | |
592 | static struct list_head *rb_list_head(struct list_head *list); | |
593 | static void verify_event(struct ring_buffer_per_cpu *cpu_buffer, | |
594 | void *event) | |
595 | { | |
596 | struct buffer_page *page = cpu_buffer->commit_page; | |
597 | struct buffer_page *tail_page = READ_ONCE(cpu_buffer->tail_page); | |
598 | struct list_head *next; | |
599 | long commit, write; | |
600 | unsigned long addr = (unsigned long)event; | |
601 | bool done = false; | |
602 | int stop = 0; | |
603 | ||
604 | /* Make sure the event exists and is not committed yet */ | |
605 | do { | |
606 | if (page == tail_page || WARN_ON_ONCE(stop++ > 100)) | |
607 | done = true; | |
608 | commit = local_read(&page->page->commit); | |
609 | write = local_read(&page->write); | |
610 | if (addr >= (unsigned long)&page->page->data[commit] && | |
611 | addr < (unsigned long)&page->page->data[write]) | |
612 | return; | |
613 | ||
614 | next = rb_list_head(page->list.next); | |
615 | page = list_entry(next, struct buffer_page, list); | |
616 | } while (!done); | |
617 | WARN_ON_ONCE(1); | |
618 | } | |
619 | #else | |
620 | static inline void verify_event(struct ring_buffer_per_cpu *cpu_buffer, | |
621 | void *event) | |
622 | { | |
623 | } | |
624 | #endif | |
625 | ||
6695da58 SRG |
626 | /* |
627 | * The absolute time stamp drops the 5 MSBs and some clocks may | |
628 | * require them. The rb_fix_abs_ts() will take a previous full | |
629 | * time stamp, and add the 5 MSB of that time stamp on to the | |
630 | * saved absolute time stamp. Then they are compared in case of | |
631 | * the unlikely event that the latest time stamp incremented | |
632 | * the 5 MSB. | |
633 | */ | |
634 | static inline u64 rb_fix_abs_ts(u64 abs, u64 save_ts) | |
635 | { | |
636 | if (save_ts & TS_MSB) { | |
637 | abs |= save_ts & TS_MSB; | |
638 | /* Check for overflow */ | |
639 | if (unlikely(abs < save_ts)) | |
640 | abs += 1ULL << 59; | |
641 | } | |
642 | return abs; | |
643 | } | |
a948c69d | 644 | |
efe6196a SRV |
645 | static inline u64 rb_time_stamp(struct trace_buffer *buffer); |
646 | ||
647 | /** | |
648 | * ring_buffer_event_time_stamp - return the event's current time stamp | |
649 | * @buffer: The buffer that the event is on | |
650 | * @event: the event to get the time stamp of | |
651 | * | |
652 | * Note, this must be called after @event is reserved, and before it is | |
653 | * committed to the ring buffer. And must be called from the same | |
654 | * context where the event was reserved (normal, softirq, irq, etc). | |
655 | * | |
656 | * Returns the time stamp associated with the current event. | |
657 | * If the event has an extended time stamp, then that is used as | |
658 | * the time stamp to return. | |
659 | * In the highly unlikely case that the event was nested more than | |
660 | * the max nesting, then the write_stamp of the buffer is returned, | |
661 | * otherwise current time is returned, but that really neither of | |
662 | * the last two cases should ever happen. | |
663 | */ | |
664 | u64 ring_buffer_event_time_stamp(struct trace_buffer *buffer, | |
665 | struct ring_buffer_event *event) | |
666 | { | |
667 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[smp_processor_id()]; | |
668 | unsigned int nest; | |
669 | u64 ts; | |
670 | ||
671 | /* If the event includes an absolute time, then just use that */ | |
6695da58 SRG |
672 | if (event->type_len == RINGBUF_TYPE_TIME_STAMP) { |
673 | ts = rb_event_time_stamp(event); | |
674 | return rb_fix_abs_ts(ts, cpu_buffer->tail_page->page->time_stamp); | |
675 | } | |
efe6196a | 676 | |
a948c69d SRV |
677 | nest = local_read(&cpu_buffer->committing); |
678 | verify_event(cpu_buffer, event); | |
679 | if (WARN_ON_ONCE(!nest)) | |
680 | goto fail; | |
681 | ||
efe6196a | 682 | /* Read the current saved nesting level time stamp */ |
a948c69d | 683 | if (likely(--nest < MAX_NEST)) |
efe6196a SRV |
684 | return cpu_buffer->event_stamp[nest]; |
685 | ||
a948c69d SRV |
686 | /* Shouldn't happen, warn if it does */ |
687 | WARN_ONCE(1, "nest (%d) greater than max", nest); | |
efe6196a | 688 | |
a948c69d | 689 | fail: |
c84897c0 | 690 | rb_time_read(&cpu_buffer->write_stamp, &ts); |
efe6196a SRV |
691 | |
692 | return ts; | |
693 | } | |
694 | ||
2c2b0a78 | 695 | /** |
b7085b6f | 696 | * ring_buffer_nr_dirty_pages - get the number of used pages in the ring buffer |
2c2b0a78 SRV |
697 | * @buffer: The ring_buffer to get the number of pages from |
698 | * @cpu: The cpu of the ring_buffer to get the number of pages from | |
699 | * | |
700 | * Returns the number of pages that have content in the ring buffer. | |
701 | */ | |
13292494 | 702 | size_t ring_buffer_nr_dirty_pages(struct trace_buffer *buffer, int cpu) |
2c2b0a78 SRV |
703 | { |
704 | size_t read; | |
31029a8b | 705 | size_t lost; |
2c2b0a78 SRV |
706 | size_t cnt; |
707 | ||
708 | read = local_read(&buffer->buffers[cpu]->pages_read); | |
31029a8b | 709 | lost = local_read(&buffer->buffers[cpu]->pages_lost); |
2c2b0a78 | 710 | cnt = local_read(&buffer->buffers[cpu]->pages_touched); |
31029a8b SRG |
711 | |
712 | if (WARN_ON_ONCE(cnt < lost)) | |
713 | return 0; | |
714 | ||
715 | cnt -= lost; | |
716 | ||
2c2b0a78 SRV |
717 | /* The reader can read an empty page, but not more than that */ |
718 | if (cnt < read) { | |
719 | WARN_ON_ONCE(read > cnt + 1); | |
720 | return 0; | |
721 | } | |
722 | ||
723 | return cnt - read; | |
724 | } | |
725 | ||
42fb0a1e SRG |
726 | static __always_inline bool full_hit(struct trace_buffer *buffer, int cpu, int full) |
727 | { | |
728 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
729 | size_t nr_pages; | |
730 | size_t dirty; | |
731 | ||
732 | nr_pages = cpu_buffer->nr_pages; | |
733 | if (!nr_pages || !full) | |
734 | return true; | |
735 | ||
623b1f89 SRG |
736 | /* |
737 | * Add one as dirty will never equal nr_pages, as the sub-buffer | |
738 | * that the writer is on is not counted as dirty. | |
739 | * This is needed if "buffer_percent" is set to 100. | |
740 | */ | |
741 | dirty = ring_buffer_nr_dirty_pages(buffer, cpu) + 1; | |
42fb0a1e | 742 | |
623b1f89 | 743 | return (dirty * 100) >= (full * nr_pages); |
42fb0a1e SRG |
744 | } |
745 | ||
15693458 SRRH |
746 | /* |
747 | * rb_wake_up_waiters - wake up tasks waiting for ring buffer input | |
748 | * | |
749 | * Schedules a delayed work to wake up any task that is blocked on the | |
750 | * ring buffer waiters queue. | |
751 | */ | |
752 | static void rb_wake_up_waiters(struct irq_work *work) | |
753 | { | |
754 | struct rb_irq_work *rbwork = container_of(work, struct rb_irq_work, work); | |
755 | ||
b70f2938 SRG |
756 | /* For waiters waiting for the first wake up */ |
757 | (void)atomic_fetch_inc_release(&rbwork->seq); | |
758 | ||
15693458 | 759 | wake_up_all(&rbwork->waiters); |
ec0bbc5e | 760 | if (rbwork->full_waiters_pending || rbwork->wakeup_full) { |
68282dd9 SRG |
761 | /* Only cpu_buffer sets the above flags */ |
762 | struct ring_buffer_per_cpu *cpu_buffer = | |
763 | container_of(rbwork, struct ring_buffer_per_cpu, irq_work); | |
764 | ||
765 | /* Called from interrupt context */ | |
766 | raw_spin_lock(&cpu_buffer->reader_lock); | |
1e0d6714 | 767 | rbwork->wakeup_full = false; |
ec0bbc5e | 768 | rbwork->full_waiters_pending = false; |
68282dd9 SRG |
769 | |
770 | /* Waking up all waiters, they will reset the shortest full */ | |
771 | cpu_buffer->shortest_full = 0; | |
772 | raw_spin_unlock(&cpu_buffer->reader_lock); | |
773 | ||
1e0d6714 SRRH |
774 | wake_up_all(&rbwork->full_waiters); |
775 | } | |
15693458 SRRH |
776 | } |
777 | ||
7e9fbbb1 SRG |
778 | /** |
779 | * ring_buffer_wake_waiters - wake up any waiters on this ring buffer | |
780 | * @buffer: The ring buffer to wake waiters on | |
151e34d1 | 781 | * @cpu: The CPU buffer to wake waiters on |
7e9fbbb1 SRG |
782 | * |
783 | * In the case of a file that represents a ring buffer is closing, | |
784 | * it is prudent to wake up any waiters that are on this. | |
785 | */ | |
786 | void ring_buffer_wake_waiters(struct trace_buffer *buffer, int cpu) | |
787 | { | |
788 | struct ring_buffer_per_cpu *cpu_buffer; | |
789 | struct rb_irq_work *rbwork; | |
790 | ||
7433632c SRG |
791 | if (!buffer) |
792 | return; | |
793 | ||
7e9fbbb1 SRG |
794 | if (cpu == RING_BUFFER_ALL_CPUS) { |
795 | ||
796 | /* Wake up individual ones too. One level recursion */ | |
797 | for_each_buffer_cpu(buffer, cpu) | |
798 | ring_buffer_wake_waiters(buffer, cpu); | |
799 | ||
800 | rbwork = &buffer->irq_work; | |
801 | } else { | |
7433632c SRG |
802 | if (WARN_ON_ONCE(!buffer->buffers)) |
803 | return; | |
804 | if (WARN_ON_ONCE(cpu >= nr_cpu_ids)) | |
805 | return; | |
806 | ||
7e9fbbb1 | 807 | cpu_buffer = buffer->buffers[cpu]; |
7433632c SRG |
808 | /* The CPU buffer may not have been initialized yet */ |
809 | if (!cpu_buffer) | |
810 | return; | |
7e9fbbb1 SRG |
811 | rbwork = &cpu_buffer->irq_work; |
812 | } | |
813 | ||
39a7dc23 SRG |
814 | /* This can be called in any context */ |
815 | irq_work_queue(&rbwork->work); | |
7e9fbbb1 SRG |
816 | } |
817 | ||
b3594573 SRG |
818 | static bool rb_watermark_hit(struct trace_buffer *buffer, int cpu, int full) |
819 | { | |
820 | struct ring_buffer_per_cpu *cpu_buffer; | |
821 | bool ret = false; | |
822 | ||
823 | /* Reads of all CPUs always waits for any data */ | |
824 | if (cpu == RING_BUFFER_ALL_CPUS) | |
825 | return !ring_buffer_empty(buffer); | |
826 | ||
827 | cpu_buffer = buffer->buffers[cpu]; | |
828 | ||
829 | if (!ring_buffer_empty_cpu(buffer, cpu)) { | |
830 | unsigned long flags; | |
831 | bool pagebusy; | |
832 | ||
833 | if (!full) | |
834 | return true; | |
835 | ||
836 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
837 | pagebusy = cpu_buffer->reader_page == cpu_buffer->commit_page; | |
838 | ret = !pagebusy && full_hit(buffer, cpu, full); | |
839 | ||
761d9473 SRG |
840 | if (!ret && (!cpu_buffer->shortest_full || |
841 | cpu_buffer->shortest_full > full)) { | |
842 | cpu_buffer->shortest_full = full; | |
843 | } | |
b3594573 SRG |
844 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
845 | } | |
846 | return ret; | |
847 | } | |
848 | ||
7af9ded0 SRG |
849 | static inline bool |
850 | rb_wait_cond(struct rb_irq_work *rbwork, struct trace_buffer *buffer, | |
851 | int cpu, int full, ring_buffer_cond_fn cond, void *data) | |
15693458 | 852 | { |
7af9ded0 SRG |
853 | if (rb_watermark_hit(buffer, cpu, full)) |
854 | return true; | |
15693458 | 855 | |
7af9ded0 SRG |
856 | if (cond(data)) |
857 | return true; | |
b3594573 SRG |
858 | |
859 | /* | |
860 | * The events can happen in critical sections where | |
861 | * checking a work queue can cause deadlocks. | |
862 | * After adding a task to the queue, this flag is set | |
863 | * only to notify events to try to wake up the queue | |
864 | * using irq_work. | |
865 | * | |
866 | * We don't clear it even if the buffer is no longer | |
867 | * empty. The flag only causes the next event to run | |
868 | * irq_work to do the work queue wake up. The worse | |
869 | * that can happen if we race with !trace_empty() is that | |
870 | * an event will cause an irq_work to try to wake up | |
871 | * an empty queue. | |
872 | * | |
873 | * There's no reason to protect this flag either, as | |
874 | * the work queue and irq_work logic will do the necessary | |
875 | * synchronization for the wake ups. The only thing | |
876 | * that is necessary is that the wake up happens after | |
877 | * a task has been queued. It's OK for spurious wake ups. | |
878 | */ | |
879 | if (full) | |
7af9ded0 | 880 | rbwork->full_waiters_pending = true; |
b3594573 | 881 | else |
7af9ded0 | 882 | rbwork->waiters_pending = true; |
b3594573 | 883 | |
7af9ded0 SRG |
884 | return false; |
885 | } | |
b3594573 | 886 | |
b70f2938 SRG |
887 | struct rb_wait_data { |
888 | struct rb_irq_work *irq_work; | |
889 | int seq; | |
890 | }; | |
891 | ||
7af9ded0 SRG |
892 | /* |
893 | * The default wait condition for ring_buffer_wait() is to just to exit the | |
894 | * wait loop the first time it is woken up. | |
895 | */ | |
896 | static bool rb_wait_once(void *data) | |
897 | { | |
b70f2938 SRG |
898 | struct rb_wait_data *rdata = data; |
899 | struct rb_irq_work *rbwork = rdata->irq_work; | |
7af9ded0 | 900 | |
b70f2938 | 901 | return atomic_read_acquire(&rbwork->seq) != rdata->seq; |
7af9ded0 | 902 | } |
b3594573 | 903 | |
7af9ded0 SRG |
904 | /** |
905 | * ring_buffer_wait - wait for input to the ring buffer | |
906 | * @buffer: buffer to wait on | |
907 | * @cpu: the cpu buffer to wait on | |
908 | * @full: wait until the percentage of pages are available, if @cpu != RING_BUFFER_ALL_CPUS | |
2aa043a5 SRG |
909 | * @cond: condition function to break out of wait (NULL to run once) |
910 | * @data: the data to pass to @cond. | |
7af9ded0 SRG |
911 | * |
912 | * If @cpu == RING_BUFFER_ALL_CPUS then the task will wake up as soon | |
913 | * as data is added to any of the @buffer's cpu buffers. Otherwise | |
914 | * it will wait for data to be added to a specific cpu buffer. | |
915 | */ | |
2aa043a5 SRG |
916 | int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full, |
917 | ring_buffer_cond_fn cond, void *data) | |
7af9ded0 SRG |
918 | { |
919 | struct ring_buffer_per_cpu *cpu_buffer; | |
920 | struct wait_queue_head *waitq; | |
7af9ded0 | 921 | struct rb_irq_work *rbwork; |
b70f2938 | 922 | struct rb_wait_data rdata; |
7af9ded0 SRG |
923 | int ret = 0; |
924 | ||
7af9ded0 SRG |
925 | /* |
926 | * Depending on what the caller is waiting for, either any | |
927 | * data in any cpu buffer, or a specific buffer, put the | |
928 | * caller on the appropriate wait queue. | |
929 | */ | |
930 | if (cpu == RING_BUFFER_ALL_CPUS) { | |
931 | rbwork = &buffer->irq_work; | |
932 | /* Full only makes sense on per cpu reads */ | |
933 | full = 0; | |
934 | } else { | |
935 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
936 | return -ENODEV; | |
937 | cpu_buffer = buffer->buffers[cpu]; | |
938 | rbwork = &cpu_buffer->irq_work; | |
e30f53aa | 939 | } |
15693458 | 940 | |
1e0d6714 | 941 | if (full) |
7af9ded0 | 942 | waitq = &rbwork->full_waiters; |
1e0d6714 | 943 | else |
7af9ded0 | 944 | waitq = &rbwork->waiters; |
e30f53aa | 945 | |
b70f2938 SRG |
946 | /* Set up to exit loop as soon as it is woken */ |
947 | if (!cond) { | |
948 | cond = rb_wait_once; | |
949 | rdata.irq_work = rbwork; | |
950 | rdata.seq = atomic_read_acquire(&rbwork->seq); | |
951 | data = &rdata; | |
952 | } | |
953 | ||
7af9ded0 SRG |
954 | ret = wait_event_interruptible((*waitq), |
955 | rb_wait_cond(rbwork, buffer, cpu, full, cond, data)); | |
b3594573 | 956 | |
e30f53aa | 957 | return ret; |
15693458 SRRH |
958 | } |
959 | ||
960 | /** | |
961 | * ring_buffer_poll_wait - poll on buffer input | |
962 | * @buffer: buffer to wait on | |
963 | * @cpu: the cpu buffer to wait on | |
964 | * @filp: the file descriptor | |
965 | * @poll_table: The poll descriptor | |
42fb0a1e | 966 | * @full: wait until the percentage of pages are available, if @cpu != RING_BUFFER_ALL_CPUS |
15693458 SRRH |
967 | * |
968 | * If @cpu == RING_BUFFER_ALL_CPUS then the task will wake up as soon | |
969 | * as data is added to any of the @buffer's cpu buffers. Otherwise | |
970 | * it will wait for data to be added to a specific cpu buffer. | |
971 | * | |
a9a08845 | 972 | * Returns EPOLLIN | EPOLLRDNORM if data exists in the buffers, |
15693458 SRRH |
973 | * zero otherwise. |
974 | */ | |
13292494 | 975 | __poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu, |
42fb0a1e | 976 | struct file *filp, poll_table *poll_table, int full) |
15693458 SRRH |
977 | { |
978 | struct ring_buffer_per_cpu *cpu_buffer; | |
68282dd9 | 979 | struct rb_irq_work *rbwork; |
15693458 | 980 | |
42fb0a1e | 981 | if (cpu == RING_BUFFER_ALL_CPUS) { |
68282dd9 | 982 | rbwork = &buffer->irq_work; |
42fb0a1e SRG |
983 | full = 0; |
984 | } else { | |
6721cb60 | 985 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
66bbea9e | 986 | return EPOLLERR; |
6721cb60 | 987 | |
15693458 | 988 | cpu_buffer = buffer->buffers[cpu]; |
68282dd9 | 989 | rbwork = &cpu_buffer->irq_work; |
15693458 SRRH |
990 | } |
991 | ||
42fb0a1e | 992 | if (full) { |
68282dd9 SRG |
993 | poll_wait(filp, &rbwork->full_waiters, poll_table); |
994 | ||
e36f19a6 | 995 | if (rb_watermark_hit(buffer, cpu, full)) |
8145f1c3 SRG |
996 | return EPOLLIN | EPOLLRDNORM; |
997 | /* | |
998 | * Only allow full_waiters_pending update to be seen after | |
e36f19a6 SRG |
999 | * the shortest_full is set (in rb_watermark_hit). If the |
1000 | * writer sees the full_waiters_pending flag set, it will | |
1001 | * compare the amount in the ring buffer to shortest_full. | |
1002 | * If the amount in the ring buffer is greater than the | |
1003 | * shortest_full percent, it will call the irq_work handler | |
1004 | * to wake up this list. The irq_handler will reset shortest_full | |
8145f1c3 SRG |
1005 | * back to zero. That's done under the reader_lock, but |
1006 | * the below smp_mb() makes sure that the update to | |
1007 | * full_waiters_pending doesn't leak up into the above. | |
1008 | */ | |
1009 | smp_mb(); | |
68282dd9 | 1010 | rbwork->full_waiters_pending = true; |
8145f1c3 | 1011 | return 0; |
42fb0a1e SRG |
1012 | } |
1013 | ||
8145f1c3 SRG |
1014 | poll_wait(filp, &rbwork->waiters, poll_table); |
1015 | rbwork->waiters_pending = true; | |
1016 | ||
4ce97dbf JB |
1017 | /* |
1018 | * There's a tight race between setting the waiters_pending and | |
1019 | * checking if the ring buffer is empty. Once the waiters_pending bit | |
1020 | * is set, the next event will wake the task up, but we can get stuck | |
1021 | * if there's only a single event in. | |
1022 | * | |
1023 | * FIXME: Ideally, we need a memory barrier on the writer side as well, | |
1024 | * but adding a memory barrier to all events will cause too much of a | |
1025 | * performance hit in the fast path. We only need a memory barrier when | |
1026 | * the buffer goes from empty to having content. But as this race is | |
1027 | * extremely small, and it's not a problem if another event comes in, we | |
1028 | * will fix it later. | |
1029 | */ | |
1030 | smp_mb(); | |
15693458 SRRH |
1031 | |
1032 | if ((cpu == RING_BUFFER_ALL_CPUS && !ring_buffer_empty(buffer)) || | |
1033 | (cpu != RING_BUFFER_ALL_CPUS && !ring_buffer_empty_cpu(buffer, cpu))) | |
a9a08845 | 1034 | return EPOLLIN | EPOLLRDNORM; |
15693458 SRRH |
1035 | return 0; |
1036 | } | |
1037 | ||
f536aafc | 1038 | /* buffer may be either ring_buffer or ring_buffer_per_cpu */ |
077c5407 SR |
1039 | #define RB_WARN_ON(b, cond) \ |
1040 | ({ \ | |
1041 | int _____ret = unlikely(cond); \ | |
1042 | if (_____ret) { \ | |
1043 | if (__same_type(*(b), struct ring_buffer_per_cpu)) { \ | |
1044 | struct ring_buffer_per_cpu *__b = \ | |
1045 | (void *)b; \ | |
1046 | atomic_inc(&__b->buffer->record_disabled); \ | |
1047 | } else \ | |
1048 | atomic_inc(&b->record_disabled); \ | |
1049 | WARN_ON(1); \ | |
1050 | } \ | |
1051 | _____ret; \ | |
3e89c7bb | 1052 | }) |
f536aafc | 1053 | |
37886f6a SR |
1054 | /* Up this if you want to test the TIME_EXTENTS and normalization */ |
1055 | #define DEBUG_SHIFT 0 | |
1056 | ||
13292494 | 1057 | static inline u64 rb_time_stamp(struct trace_buffer *buffer) |
88eb0125 | 1058 | { |
bbeba3e5 SRV |
1059 | u64 ts; |
1060 | ||
1061 | /* Skip retpolines :-( */ | |
aefb2f2e | 1062 | if (IS_ENABLED(CONFIG_MITIGATION_RETPOLINE) && likely(buffer->clock == trace_clock_local)) |
bbeba3e5 SRV |
1063 | ts = trace_clock_local(); |
1064 | else | |
1065 | ts = buffer->clock(); | |
1066 | ||
88eb0125 | 1067 | /* shift to debug/test normalization and TIME_EXTENTS */ |
bbeba3e5 | 1068 | return ts << DEBUG_SHIFT; |
88eb0125 SR |
1069 | } |
1070 | ||
f3ef7202 | 1071 | u64 ring_buffer_time_stamp(struct trace_buffer *buffer) |
37886f6a SR |
1072 | { |
1073 | u64 time; | |
1074 | ||
1075 | preempt_disable_notrace(); | |
6d3f1e12 | 1076 | time = rb_time_stamp(buffer); |
d6097c9e | 1077 | preempt_enable_notrace(); |
37886f6a SR |
1078 | |
1079 | return time; | |
1080 | } | |
1081 | EXPORT_SYMBOL_GPL(ring_buffer_time_stamp); | |
1082 | ||
13292494 | 1083 | void ring_buffer_normalize_time_stamp(struct trace_buffer *buffer, |
37886f6a SR |
1084 | int cpu, u64 *ts) |
1085 | { | |
1086 | /* Just stupid testing the normalize function and deltas */ | |
1087 | *ts >>= DEBUG_SHIFT; | |
1088 | } | |
1089 | EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp); | |
1090 | ||
77ae365e SR |
1091 | /* |
1092 | * Making the ring buffer lockless makes things tricky. | |
1093 | * Although writes only happen on the CPU that they are on, | |
1094 | * and they only need to worry about interrupts. Reads can | |
1095 | * happen on any CPU. | |
1096 | * | |
1097 | * The reader page is always off the ring buffer, but when the | |
1098 | * reader finishes with a page, it needs to swap its page with | |
1099 | * a new one from the buffer. The reader needs to take from | |
1100 | * the head (writes go to the tail). But if a writer is in overwrite | |
1101 | * mode and wraps, it must push the head page forward. | |
1102 | * | |
1103 | * Here lies the problem. | |
1104 | * | |
1105 | * The reader must be careful to replace only the head page, and | |
1106 | * not another one. As described at the top of the file in the | |
1107 | * ASCII art, the reader sets its old page to point to the next | |
1108 | * page after head. It then sets the page after head to point to | |
1109 | * the old reader page. But if the writer moves the head page | |
1110 | * during this operation, the reader could end up with the tail. | |
1111 | * | |
1112 | * We use cmpxchg to help prevent this race. We also do something | |
1113 | * special with the page before head. We set the LSB to 1. | |
1114 | * | |
1115 | * When the writer must push the page forward, it will clear the | |
1116 | * bit that points to the head page, move the head, and then set | |
1117 | * the bit that points to the new head page. | |
1118 | * | |
1119 | * We also don't want an interrupt coming in and moving the head | |
1120 | * page on another writer. Thus we use the second LSB to catch | |
1121 | * that too. Thus: | |
1122 | * | |
1123 | * head->list->prev->next bit 1 bit 0 | |
1124 | * ------- ------- | |
1125 | * Normal page 0 0 | |
1126 | * Points to head page 0 1 | |
1127 | * New head page 1 0 | |
1128 | * | |
1129 | * Note we can not trust the prev pointer of the head page, because: | |
1130 | * | |
1131 | * +----+ +-----+ +-----+ | |
1132 | * | |------>| T |---X--->| N | | |
1133 | * | |<------| | | | | |
1134 | * +----+ +-----+ +-----+ | |
1135 | * ^ ^ | | |
1136 | * | +-----+ | | | |
1137 | * +----------| R |----------+ | | |
1138 | * | |<-----------+ | |
1139 | * +-----+ | |
1140 | * | |
1141 | * Key: ---X--> HEAD flag set in pointer | |
1142 | * T Tail page | |
1143 | * R Reader page | |
1144 | * N Next page | |
1145 | * | |
1146 | * (see __rb_reserve_next() to see where this happens) | |
1147 | * | |
1148 | * What the above shows is that the reader just swapped out | |
1149 | * the reader page with a page in the buffer, but before it | |
1150 | * could make the new header point back to the new page added | |
1151 | * it was preempted by a writer. The writer moved forward onto | |
1152 | * the new page added by the reader and is about to move forward | |
1153 | * again. | |
1154 | * | |
1155 | * You can see, it is legitimate for the previous pointer of | |
1156 | * the head (or any page) not to point back to itself. But only | |
6167c205 | 1157 | * temporarily. |
77ae365e SR |
1158 | */ |
1159 | ||
1160 | #define RB_PAGE_NORMAL 0UL | |
1161 | #define RB_PAGE_HEAD 1UL | |
1162 | #define RB_PAGE_UPDATE 2UL | |
1163 | ||
1164 | ||
1165 | #define RB_FLAG_MASK 3UL | |
1166 | ||
1167 | /* PAGE_MOVED is not part of the mask */ | |
1168 | #define RB_PAGE_MOVED 4UL | |
1169 | ||
1170 | /* | |
1171 | * rb_list_head - remove any bit | |
1172 | */ | |
1173 | static struct list_head *rb_list_head(struct list_head *list) | |
1174 | { | |
1175 | unsigned long val = (unsigned long)list; | |
1176 | ||
1177 | return (struct list_head *)(val & ~RB_FLAG_MASK); | |
1178 | } | |
1179 | ||
1180 | /* | |
6d3f1e12 | 1181 | * rb_is_head_page - test if the given page is the head page |
77ae365e SR |
1182 | * |
1183 | * Because the reader may move the head_page pointer, we can | |
1184 | * not trust what the head page is (it may be pointing to | |
1185 | * the reader page). But if the next page is a header page, | |
1186 | * its flags will be non zero. | |
1187 | */ | |
42b16b3f | 1188 | static inline int |
6689bed3 | 1189 | rb_is_head_page(struct buffer_page *page, struct list_head *list) |
77ae365e SR |
1190 | { |
1191 | unsigned long val; | |
1192 | ||
1193 | val = (unsigned long)list->next; | |
1194 | ||
1195 | if ((val & ~RB_FLAG_MASK) != (unsigned long)&page->list) | |
1196 | return RB_PAGE_MOVED; | |
1197 | ||
1198 | return val & RB_FLAG_MASK; | |
1199 | } | |
1200 | ||
1201 | /* | |
1202 | * rb_is_reader_page | |
1203 | * | |
1204 | * The unique thing about the reader page, is that, if the | |
1205 | * writer is ever on it, the previous pointer never points | |
1206 | * back to the reader page. | |
1207 | */ | |
06ca3209 | 1208 | static bool rb_is_reader_page(struct buffer_page *page) |
77ae365e SR |
1209 | { |
1210 | struct list_head *list = page->list.prev; | |
1211 | ||
1212 | return rb_list_head(list->next) != &page->list; | |
1213 | } | |
1214 | ||
1215 | /* | |
1216 | * rb_set_list_to_head - set a list_head to be pointing to head. | |
1217 | */ | |
6689bed3 | 1218 | static void rb_set_list_to_head(struct list_head *list) |
77ae365e SR |
1219 | { |
1220 | unsigned long *ptr; | |
1221 | ||
1222 | ptr = (unsigned long *)&list->next; | |
1223 | *ptr |= RB_PAGE_HEAD; | |
1224 | *ptr &= ~RB_PAGE_UPDATE; | |
1225 | } | |
1226 | ||
1227 | /* | |
1228 | * rb_head_page_activate - sets up head page | |
1229 | */ | |
1230 | static void rb_head_page_activate(struct ring_buffer_per_cpu *cpu_buffer) | |
1231 | { | |
1232 | struct buffer_page *head; | |
1233 | ||
1234 | head = cpu_buffer->head_page; | |
1235 | if (!head) | |
1236 | return; | |
1237 | ||
1238 | /* | |
1239 | * Set the previous list pointer to have the HEAD flag. | |
1240 | */ | |
6689bed3 | 1241 | rb_set_list_to_head(head->list.prev); |
77ae365e SR |
1242 | } |
1243 | ||
1244 | static void rb_list_head_clear(struct list_head *list) | |
1245 | { | |
1246 | unsigned long *ptr = (unsigned long *)&list->next; | |
1247 | ||
1248 | *ptr &= ~RB_FLAG_MASK; | |
1249 | } | |
1250 | ||
1251 | /* | |
6167c205 | 1252 | * rb_head_page_deactivate - clears head page ptr (for free list) |
77ae365e SR |
1253 | */ |
1254 | static void | |
1255 | rb_head_page_deactivate(struct ring_buffer_per_cpu *cpu_buffer) | |
1256 | { | |
1257 | struct list_head *hd; | |
1258 | ||
1259 | /* Go through the whole list and clear any pointers found. */ | |
1260 | rb_list_head_clear(cpu_buffer->pages); | |
1261 | ||
1262 | list_for_each(hd, cpu_buffer->pages) | |
1263 | rb_list_head_clear(hd); | |
1264 | } | |
1265 | ||
1266 | static int rb_head_page_set(struct ring_buffer_per_cpu *cpu_buffer, | |
1267 | struct buffer_page *head, | |
1268 | struct buffer_page *prev, | |
1269 | int old_flag, int new_flag) | |
1270 | { | |
1271 | struct list_head *list; | |
1272 | unsigned long val = (unsigned long)&head->list; | |
1273 | unsigned long ret; | |
1274 | ||
1275 | list = &prev->list; | |
1276 | ||
1277 | val &= ~RB_FLAG_MASK; | |
1278 | ||
08a40816 SR |
1279 | ret = cmpxchg((unsigned long *)&list->next, |
1280 | val | old_flag, val | new_flag); | |
77ae365e SR |
1281 | |
1282 | /* check if the reader took the page */ | |
1283 | if ((ret & ~RB_FLAG_MASK) != val) | |
1284 | return RB_PAGE_MOVED; | |
1285 | ||
1286 | return ret & RB_FLAG_MASK; | |
1287 | } | |
1288 | ||
1289 | static int rb_head_page_set_update(struct ring_buffer_per_cpu *cpu_buffer, | |
1290 | struct buffer_page *head, | |
1291 | struct buffer_page *prev, | |
1292 | int old_flag) | |
1293 | { | |
1294 | return rb_head_page_set(cpu_buffer, head, prev, | |
1295 | old_flag, RB_PAGE_UPDATE); | |
1296 | } | |
1297 | ||
1298 | static int rb_head_page_set_head(struct ring_buffer_per_cpu *cpu_buffer, | |
1299 | struct buffer_page *head, | |
1300 | struct buffer_page *prev, | |
1301 | int old_flag) | |
1302 | { | |
1303 | return rb_head_page_set(cpu_buffer, head, prev, | |
1304 | old_flag, RB_PAGE_HEAD); | |
1305 | } | |
1306 | ||
1307 | static int rb_head_page_set_normal(struct ring_buffer_per_cpu *cpu_buffer, | |
1308 | struct buffer_page *head, | |
1309 | struct buffer_page *prev, | |
1310 | int old_flag) | |
1311 | { | |
1312 | return rb_head_page_set(cpu_buffer, head, prev, | |
1313 | old_flag, RB_PAGE_NORMAL); | |
1314 | } | |
1315 | ||
6689bed3 | 1316 | static inline void rb_inc_page(struct buffer_page **bpage) |
77ae365e SR |
1317 | { |
1318 | struct list_head *p = rb_list_head((*bpage)->list.next); | |
1319 | ||
1320 | *bpage = list_entry(p, struct buffer_page, list); | |
1321 | } | |
1322 | ||
1323 | static struct buffer_page * | |
1324 | rb_set_head_page(struct ring_buffer_per_cpu *cpu_buffer) | |
1325 | { | |
1326 | struct buffer_page *head; | |
1327 | struct buffer_page *page; | |
1328 | struct list_head *list; | |
1329 | int i; | |
1330 | ||
1331 | if (RB_WARN_ON(cpu_buffer, !cpu_buffer->head_page)) | |
1332 | return NULL; | |
1333 | ||
1334 | /* sanity check */ | |
1335 | list = cpu_buffer->pages; | |
1336 | if (RB_WARN_ON(cpu_buffer, rb_list_head(list->prev->next) != list)) | |
1337 | return NULL; | |
1338 | ||
1339 | page = head = cpu_buffer->head_page; | |
1340 | /* | |
1341 | * It is possible that the writer moves the header behind | |
1342 | * where we started, and we miss in one loop. | |
1343 | * A second loop should grab the header, but we'll do | |
1344 | * three loops just because I'm paranoid. | |
1345 | */ | |
1346 | for (i = 0; i < 3; i++) { | |
1347 | do { | |
6689bed3 | 1348 | if (rb_is_head_page(page, page->list.prev)) { |
77ae365e SR |
1349 | cpu_buffer->head_page = page; |
1350 | return page; | |
1351 | } | |
6689bed3 | 1352 | rb_inc_page(&page); |
77ae365e SR |
1353 | } while (page != head); |
1354 | } | |
1355 | ||
1356 | RB_WARN_ON(cpu_buffer, 1); | |
1357 | ||
1358 | return NULL; | |
1359 | } | |
1360 | ||
bc92b956 | 1361 | static bool rb_head_page_replace(struct buffer_page *old, |
77ae365e SR |
1362 | struct buffer_page *new) |
1363 | { | |
1364 | unsigned long *ptr = (unsigned long *)&old->list.prev->next; | |
1365 | unsigned long val; | |
77ae365e SR |
1366 | |
1367 | val = *ptr & ~RB_FLAG_MASK; | |
1368 | val |= RB_PAGE_HEAD; | |
1369 | ||
00a8478f | 1370 | return try_cmpxchg(ptr, &val, (unsigned long)&new->list); |
77ae365e SR |
1371 | } |
1372 | ||
1373 | /* | |
1374 | * rb_tail_page_update - move the tail page forward | |
77ae365e | 1375 | */ |
70004986 | 1376 | static void rb_tail_page_update(struct ring_buffer_per_cpu *cpu_buffer, |
77ae365e SR |
1377 | struct buffer_page *tail_page, |
1378 | struct buffer_page *next_page) | |
1379 | { | |
77ae365e SR |
1380 | unsigned long old_entries; |
1381 | unsigned long old_write; | |
77ae365e SR |
1382 | |
1383 | /* | |
1384 | * The tail page now needs to be moved forward. | |
1385 | * | |
1386 | * We need to reset the tail page, but without messing | |
1387 | * with possible erasing of data brought in by interrupts | |
1388 | * that have moved the tail page and are currently on it. | |
1389 | * | |
1390 | * We add a counter to the write field to denote this. | |
1391 | */ | |
1392 | old_write = local_add_return(RB_WRITE_INTCNT, &next_page->write); | |
1393 | old_entries = local_add_return(RB_WRITE_INTCNT, &next_page->entries); | |
1394 | ||
1395 | /* | |
1396 | * Just make sure we have seen our old_write and synchronize | |
1397 | * with any interrupts that come in. | |
1398 | */ | |
1399 | barrier(); | |
1400 | ||
1401 | /* | |
1402 | * If the tail page is still the same as what we think | |
1403 | * it is, then it is up to us to update the tail | |
1404 | * pointer. | |
1405 | */ | |
8573636e | 1406 | if (tail_page == READ_ONCE(cpu_buffer->tail_page)) { |
77ae365e SR |
1407 | /* Zero the write counter */ |
1408 | unsigned long val = old_write & ~RB_WRITE_MASK; | |
1409 | unsigned long eval = old_entries & ~RB_WRITE_MASK; | |
1410 | ||
1411 | /* | |
1412 | * This will only succeed if an interrupt did | |
1413 | * not come in and change it. In which case, we | |
1414 | * do not want to modify it. | |
da706d8b LJ |
1415 | * |
1416 | * We add (void) to let the compiler know that we do not care | |
1417 | * about the return value of these functions. We use the | |
1418 | * cmpxchg to only update if an interrupt did not already | |
1419 | * do it for us. If the cmpxchg fails, we don't care. | |
77ae365e | 1420 | */ |
da706d8b LJ |
1421 | (void)local_cmpxchg(&next_page->write, old_write, val); |
1422 | (void)local_cmpxchg(&next_page->entries, old_entries, eval); | |
77ae365e SR |
1423 | |
1424 | /* | |
1425 | * No need to worry about races with clearing out the commit. | |
1426 | * it only can increment when a commit takes place. But that | |
1427 | * only happens in the outer most nested commit. | |
1428 | */ | |
1429 | local_set(&next_page->page->commit, 0); | |
1430 | ||
ffe3986f SRG |
1431 | /* Either we update tail_page or an interrupt does */ |
1432 | if (try_cmpxchg(&cpu_buffer->tail_page, &tail_page, next_page)) | |
1433 | local_inc(&cpu_buffer->pages_touched); | |
77ae365e | 1434 | } |
77ae365e SR |
1435 | } |
1436 | ||
b4b55dfd | 1437 | static void rb_check_bpage(struct ring_buffer_per_cpu *cpu_buffer, |
77ae365e SR |
1438 | struct buffer_page *bpage) |
1439 | { | |
1440 | unsigned long val = (unsigned long)bpage; | |
1441 | ||
b4b55dfd | 1442 | RB_WARN_ON(cpu_buffer, val & RB_FLAG_MASK); |
77ae365e SR |
1443 | } |
1444 | ||
7a8e76a3 | 1445 | /** |
d611851b | 1446 | * rb_check_pages - integrity check of buffer pages |
7a8e76a3 SR |
1447 | * @cpu_buffer: CPU buffer with pages to test |
1448 | * | |
c3706f00 | 1449 | * As a safety measure we check to make sure the data pages have not |
7a8e76a3 | 1450 | * been corrupted. |
c2274b90 PP |
1451 | * |
1452 | * Callers of this function need to guarantee that the list of pages doesn't get | |
1453 | * modified during the check. In particular, if it's possible that the function | |
1454 | * is invoked with concurrent readers which can swap in a new reader page then | |
1455 | * the caller should take cpu_buffer->reader_lock. | |
7a8e76a3 | 1456 | */ |
b4b55dfd | 1457 | static void rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 1458 | { |
8843e06f MO |
1459 | struct list_head *head = rb_list_head(cpu_buffer->pages); |
1460 | struct list_head *tmp; | |
308f7eeb | 1461 | |
8843e06f MO |
1462 | if (RB_WARN_ON(cpu_buffer, |
1463 | rb_list_head(rb_list_head(head->next)->prev) != head)) | |
b4b55dfd | 1464 | return; |
7a8e76a3 | 1465 | |
8843e06f MO |
1466 | if (RB_WARN_ON(cpu_buffer, |
1467 | rb_list_head(rb_list_head(head->prev)->next) != head)) | |
b4b55dfd | 1468 | return; |
77ae365e | 1469 | |
8843e06f | 1470 | for (tmp = rb_list_head(head->next); tmp != head; tmp = rb_list_head(tmp->next)) { |
3e89c7bb | 1471 | if (RB_WARN_ON(cpu_buffer, |
8843e06f | 1472 | rb_list_head(rb_list_head(tmp->next)->prev) != tmp)) |
b4b55dfd | 1473 | return; |
8843e06f | 1474 | |
3e89c7bb | 1475 | if (RB_WARN_ON(cpu_buffer, |
8843e06f | 1476 | rb_list_head(rb_list_head(tmp->prev)->next) != tmp)) |
b4b55dfd | 1477 | return; |
7a8e76a3 | 1478 | } |
7a8e76a3 SR |
1479 | } |
1480 | ||
74e2afc6 QH |
1481 | static int __rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, |
1482 | long nr_pages, struct list_head *pages) | |
7a8e76a3 | 1483 | { |
044fa782 | 1484 | struct buffer_page *bpage, *tmp; |
927e56db SRV |
1485 | bool user_thread = current->mm != NULL; |
1486 | gfp_t mflags; | |
9b94a8fb | 1487 | long i; |
3adc54fa | 1488 | |
927e56db SRV |
1489 | /* |
1490 | * Check if the available memory is there first. | |
1491 | * Note, si_mem_available() only gives us a rough estimate of available | |
1492 | * memory. It may not be accurate. But we don't care, we just want | |
1493 | * to prevent doing any allocation when it is obvious that it is | |
1494 | * not going to succeed. | |
1495 | */ | |
2a872fa4 SRV |
1496 | i = si_mem_available(); |
1497 | if (i < nr_pages) | |
1498 | return -ENOMEM; | |
1499 | ||
927e56db SRV |
1500 | /* |
1501 | * __GFP_RETRY_MAYFAIL flag makes sure that the allocation fails | |
1502 | * gracefully without invoking oom-killer and the system is not | |
1503 | * destabilized. | |
1504 | */ | |
1505 | mflags = GFP_KERNEL | __GFP_RETRY_MAYFAIL; | |
1506 | ||
1507 | /* | |
1508 | * If a user thread allocates too much, and si_mem_available() | |
1509 | * reports there's enough memory, even though there is not. | |
1510 | * Make sure the OOM killer kills this thread. This can happen | |
1511 | * even with RETRY_MAYFAIL because another task may be doing | |
1512 | * an allocation after this task has taken all memory. | |
1513 | * This is the task the OOM killer needs to take out during this | |
1514 | * loop, even if it was triggered by an allocation somewhere else. | |
1515 | */ | |
1516 | if (user_thread) | |
1517 | set_current_oom_origin(); | |
7a8e76a3 | 1518 | for (i = 0; i < nr_pages; i++) { |
7ea59064 | 1519 | struct page *page; |
927e56db | 1520 | |
044fa782 | 1521 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
74e2afc6 | 1522 | mflags, cpu_to_node(cpu_buffer->cpu)); |
044fa782 | 1523 | if (!bpage) |
e4c2ce82 | 1524 | goto free_pages; |
77ae365e | 1525 | |
74e2afc6 QH |
1526 | rb_check_bpage(cpu_buffer, bpage); |
1527 | ||
438ced17 | 1528 | list_add(&bpage->list, pages); |
77ae365e | 1529 | |
6b76323e | 1530 | page = alloc_pages_node(cpu_to_node(cpu_buffer->cpu), |
c09d4167 | 1531 | mflags | __GFP_COMP | __GFP_ZERO, |
f9b94daa | 1532 | cpu_buffer->buffer->subbuf_order); |
7ea59064 | 1533 | if (!page) |
7a8e76a3 | 1534 | goto free_pages; |
7ea59064 | 1535 | bpage->page = page_address(page); |
f9b94daa | 1536 | bpage->order = cpu_buffer->buffer->subbuf_order; |
044fa782 | 1537 | rb_init_page(bpage->page); |
927e56db SRV |
1538 | |
1539 | if (user_thread && fatal_signal_pending(current)) | |
1540 | goto free_pages; | |
7a8e76a3 | 1541 | } |
927e56db SRV |
1542 | if (user_thread) |
1543 | clear_current_oom_origin(); | |
7a8e76a3 | 1544 | |
438ced17 VN |
1545 | return 0; |
1546 | ||
1547 | free_pages: | |
1548 | list_for_each_entry_safe(bpage, tmp, pages, list) { | |
1549 | list_del_init(&bpage->list); | |
1550 | free_buffer_page(bpage); | |
1551 | } | |
927e56db SRV |
1552 | if (user_thread) |
1553 | clear_current_oom_origin(); | |
438ced17 VN |
1554 | |
1555 | return -ENOMEM; | |
1556 | } | |
1557 | ||
1558 | static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, | |
9b94a8fb | 1559 | unsigned long nr_pages) |
438ced17 VN |
1560 | { |
1561 | LIST_HEAD(pages); | |
1562 | ||
1563 | WARN_ON(!nr_pages); | |
1564 | ||
74e2afc6 | 1565 | if (__rb_allocate_pages(cpu_buffer, nr_pages, &pages)) |
438ced17 VN |
1566 | return -ENOMEM; |
1567 | ||
3adc54fa SR |
1568 | /* |
1569 | * The ring buffer page list is a circular list that does not | |
1570 | * start and end with a list head. All page list items point to | |
1571 | * other pages. | |
1572 | */ | |
1573 | cpu_buffer->pages = pages.next; | |
1574 | list_del(&pages); | |
7a8e76a3 | 1575 | |
438ced17 VN |
1576 | cpu_buffer->nr_pages = nr_pages; |
1577 | ||
7a8e76a3 SR |
1578 | rb_check_pages(cpu_buffer); |
1579 | ||
1580 | return 0; | |
7a8e76a3 SR |
1581 | } |
1582 | ||
1583 | static struct ring_buffer_per_cpu * | |
13292494 | 1584 | rb_allocate_cpu_buffer(struct trace_buffer *buffer, long nr_pages, int cpu) |
7a8e76a3 SR |
1585 | { |
1586 | struct ring_buffer_per_cpu *cpu_buffer; | |
044fa782 | 1587 | struct buffer_page *bpage; |
7ea59064 | 1588 | struct page *page; |
7a8e76a3 SR |
1589 | int ret; |
1590 | ||
1591 | cpu_buffer = kzalloc_node(ALIGN(sizeof(*cpu_buffer), cache_line_size()), | |
1592 | GFP_KERNEL, cpu_to_node(cpu)); | |
1593 | if (!cpu_buffer) | |
1594 | return NULL; | |
1595 | ||
1596 | cpu_buffer->cpu = cpu; | |
1597 | cpu_buffer->buffer = buffer; | |
5389f6fa | 1598 | raw_spin_lock_init(&cpu_buffer->reader_lock); |
1f8a6a10 | 1599 | lockdep_set_class(&cpu_buffer->reader_lock, buffer->reader_lock_key); |
edc35bd7 | 1600 | cpu_buffer->lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; |
83f40318 | 1601 | INIT_WORK(&cpu_buffer->update_pages_work, update_pages_handler); |
05fdd70d | 1602 | init_completion(&cpu_buffer->update_done); |
15693458 | 1603 | init_irq_work(&cpu_buffer->irq_work.work, rb_wake_up_waiters); |
f1dc6725 | 1604 | init_waitqueue_head(&cpu_buffer->irq_work.waiters); |
1e0d6714 | 1605 | init_waitqueue_head(&cpu_buffer->irq_work.full_waiters); |
117c3920 | 1606 | mutex_init(&cpu_buffer->mapping_lock); |
7a8e76a3 | 1607 | |
044fa782 | 1608 | bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), |
e4c2ce82 | 1609 | GFP_KERNEL, cpu_to_node(cpu)); |
044fa782 | 1610 | if (!bpage) |
e4c2ce82 SR |
1611 | goto fail_free_buffer; |
1612 | ||
77ae365e SR |
1613 | rb_check_bpage(cpu_buffer, bpage); |
1614 | ||
044fa782 | 1615 | cpu_buffer->reader_page = bpage; |
f9b94daa | 1616 | |
c09d4167 | 1617 | page = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL | __GFP_COMP | __GFP_ZERO, |
6b76323e | 1618 | cpu_buffer->buffer->subbuf_order); |
7ea59064 | 1619 | if (!page) |
e4c2ce82 | 1620 | goto fail_free_reader; |
7ea59064 | 1621 | bpage->page = page_address(page); |
044fa782 | 1622 | rb_init_page(bpage->page); |
e4c2ce82 | 1623 | |
d769041f | 1624 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); |
44b99462 | 1625 | INIT_LIST_HEAD(&cpu_buffer->new_pages); |
d769041f | 1626 | |
438ced17 | 1627 | ret = rb_allocate_pages(cpu_buffer, nr_pages); |
7a8e76a3 | 1628 | if (ret < 0) |
d769041f | 1629 | goto fail_free_reader; |
7a8e76a3 SR |
1630 | |
1631 | cpu_buffer->head_page | |
3adc54fa | 1632 | = list_entry(cpu_buffer->pages, struct buffer_page, list); |
bf41a158 | 1633 | cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; |
7a8e76a3 | 1634 | |
77ae365e SR |
1635 | rb_head_page_activate(cpu_buffer); |
1636 | ||
7a8e76a3 SR |
1637 | return cpu_buffer; |
1638 | ||
d769041f SR |
1639 | fail_free_reader: |
1640 | free_buffer_page(cpu_buffer->reader_page); | |
1641 | ||
7a8e76a3 SR |
1642 | fail_free_buffer: |
1643 | kfree(cpu_buffer); | |
1644 | return NULL; | |
1645 | } | |
1646 | ||
1647 | static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) | |
1648 | { | |
3adc54fa | 1649 | struct list_head *head = cpu_buffer->pages; |
044fa782 | 1650 | struct buffer_page *bpage, *tmp; |
7a8e76a3 | 1651 | |
675751bb JB |
1652 | irq_work_sync(&cpu_buffer->irq_work.work); |
1653 | ||
d769041f SR |
1654 | free_buffer_page(cpu_buffer->reader_page); |
1655 | ||
3adc54fa | 1656 | if (head) { |
56f4ca0a DT |
1657 | rb_head_page_deactivate(cpu_buffer); |
1658 | ||
3adc54fa SR |
1659 | list_for_each_entry_safe(bpage, tmp, head, list) { |
1660 | list_del_init(&bpage->list); | |
1661 | free_buffer_page(bpage); | |
1662 | } | |
1663 | bpage = list_entry(head, struct buffer_page, list); | |
044fa782 | 1664 | free_buffer_page(bpage); |
7a8e76a3 | 1665 | } |
3adc54fa | 1666 | |
17d80175 SRG |
1667 | free_page((unsigned long)cpu_buffer->free_page); |
1668 | ||
7a8e76a3 SR |
1669 | kfree(cpu_buffer); |
1670 | } | |
1671 | ||
1672 | /** | |
d611851b | 1673 | * __ring_buffer_alloc - allocate a new ring_buffer |
68814b58 | 1674 | * @size: the size in bytes per cpu that is needed. |
7a8e76a3 | 1675 | * @flags: attributes to set for the ring buffer. |
59e7cffe | 1676 | * @key: ring buffer reader_lock_key. |
7a8e76a3 SR |
1677 | * |
1678 | * Currently the only flag that is available is the RB_FL_OVERWRITE | |
1679 | * flag. This flag means that the buffer will overwrite old data | |
1680 | * when the buffer wraps. If this flag is not set, the buffer will | |
1681 | * drop data when the tail hits the head. | |
1682 | */ | |
13292494 | 1683 | struct trace_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, |
1f8a6a10 | 1684 | struct lock_class_key *key) |
7a8e76a3 | 1685 | { |
13292494 | 1686 | struct trace_buffer *buffer; |
9b94a8fb | 1687 | long nr_pages; |
7a8e76a3 | 1688 | int bsize; |
9b94a8fb | 1689 | int cpu; |
b32614c0 | 1690 | int ret; |
7a8e76a3 SR |
1691 | |
1692 | /* keep it in its own cache line */ | |
1693 | buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()), | |
1694 | GFP_KERNEL); | |
1695 | if (!buffer) | |
1696 | return NULL; | |
1697 | ||
b18cc3de | 1698 | if (!zalloc_cpumask_var(&buffer->cpumask, GFP_KERNEL)) |
9e01c1b7 RR |
1699 | goto fail_free_buffer; |
1700 | ||
139f8400 | 1701 | /* Default buffer page size - one system page */ |
f9b94daa | 1702 | buffer->subbuf_order = 0; |
139f8400 TSV |
1703 | buffer->subbuf_size = PAGE_SIZE - BUF_PAGE_HDR_SIZE; |
1704 | ||
1705 | /* Max payload is buffer page size - header (8bytes) */ | |
1706 | buffer->max_data_size = buffer->subbuf_size - (sizeof(u32) * 2); | |
1707 | ||
1708 | nr_pages = DIV_ROUND_UP(size, buffer->subbuf_size); | |
7a8e76a3 | 1709 | buffer->flags = flags; |
37886f6a | 1710 | buffer->clock = trace_clock_local; |
1f8a6a10 | 1711 | buffer->reader_lock_key = key; |
7a8e76a3 | 1712 | |
15693458 | 1713 | init_irq_work(&buffer->irq_work.work, rb_wake_up_waiters); |
f1dc6725 | 1714 | init_waitqueue_head(&buffer->irq_work.waiters); |
15693458 | 1715 | |
7a8e76a3 | 1716 | /* need at least two pages */ |
438ced17 VN |
1717 | if (nr_pages < 2) |
1718 | nr_pages = 2; | |
7a8e76a3 | 1719 | |
7a8e76a3 SR |
1720 | buffer->cpus = nr_cpu_ids; |
1721 | ||
1722 | bsize = sizeof(void *) * nr_cpu_ids; | |
1723 | buffer->buffers = kzalloc(ALIGN(bsize, cache_line_size()), | |
1724 | GFP_KERNEL); | |
1725 | if (!buffer->buffers) | |
9e01c1b7 | 1726 | goto fail_free_cpumask; |
7a8e76a3 | 1727 | |
b32614c0 SAS |
1728 | cpu = raw_smp_processor_id(); |
1729 | cpumask_set_cpu(cpu, buffer->cpumask); | |
1730 | buffer->buffers[cpu] = rb_allocate_cpu_buffer(buffer, nr_pages, cpu); | |
1731 | if (!buffer->buffers[cpu]) | |
1732 | goto fail_free_buffers; | |
7a8e76a3 | 1733 | |
b32614c0 SAS |
1734 | ret = cpuhp_state_add_instance(CPUHP_TRACE_RB_PREPARE, &buffer->node); |
1735 | if (ret < 0) | |
1736 | goto fail_free_buffers; | |
554f786e | 1737 | |
7a8e76a3 SR |
1738 | mutex_init(&buffer->mutex); |
1739 | ||
1740 | return buffer; | |
1741 | ||
1742 | fail_free_buffers: | |
1743 | for_each_buffer_cpu(buffer, cpu) { | |
1744 | if (buffer->buffers[cpu]) | |
1745 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
1746 | } | |
1747 | kfree(buffer->buffers); | |
1748 | ||
9e01c1b7 RR |
1749 | fail_free_cpumask: |
1750 | free_cpumask_var(buffer->cpumask); | |
1751 | ||
7a8e76a3 SR |
1752 | fail_free_buffer: |
1753 | kfree(buffer); | |
1754 | return NULL; | |
1755 | } | |
1f8a6a10 | 1756 | EXPORT_SYMBOL_GPL(__ring_buffer_alloc); |
7a8e76a3 SR |
1757 | |
1758 | /** | |
1759 | * ring_buffer_free - free a ring buffer. | |
1760 | * @buffer: the buffer to free. | |
1761 | */ | |
1762 | void | |
13292494 | 1763 | ring_buffer_free(struct trace_buffer *buffer) |
7a8e76a3 SR |
1764 | { |
1765 | int cpu; | |
1766 | ||
b32614c0 | 1767 | cpuhp_state_remove_instance(CPUHP_TRACE_RB_PREPARE, &buffer->node); |
554f786e | 1768 | |
675751bb JB |
1769 | irq_work_sync(&buffer->irq_work.work); |
1770 | ||
7a8e76a3 SR |
1771 | for_each_buffer_cpu(buffer, cpu) |
1772 | rb_free_cpu_buffer(buffer->buffers[cpu]); | |
1773 | ||
bd3f0221 | 1774 | kfree(buffer->buffers); |
9e01c1b7 RR |
1775 | free_cpumask_var(buffer->cpumask); |
1776 | ||
7a8e76a3 SR |
1777 | kfree(buffer); |
1778 | } | |
c4f50183 | 1779 | EXPORT_SYMBOL_GPL(ring_buffer_free); |
7a8e76a3 | 1780 | |
13292494 | 1781 | void ring_buffer_set_clock(struct trace_buffer *buffer, |
37886f6a SR |
1782 | u64 (*clock)(void)) |
1783 | { | |
1784 | buffer->clock = clock; | |
1785 | } | |
1786 | ||
13292494 | 1787 | void ring_buffer_set_time_stamp_abs(struct trace_buffer *buffer, bool abs) |
00b41452 TZ |
1788 | { |
1789 | buffer->time_stamp_abs = abs; | |
1790 | } | |
1791 | ||
13292494 | 1792 | bool ring_buffer_time_stamp_abs(struct trace_buffer *buffer) |
00b41452 TZ |
1793 | { |
1794 | return buffer->time_stamp_abs; | |
1795 | } | |
1796 | ||
83f40318 VN |
1797 | static inline unsigned long rb_page_entries(struct buffer_page *bpage) |
1798 | { | |
1799 | return local_read(&bpage->entries) & RB_WRITE_MASK; | |
1800 | } | |
1801 | ||
1802 | static inline unsigned long rb_page_write(struct buffer_page *bpage) | |
1803 | { | |
1804 | return local_read(&bpage->write) & RB_WRITE_MASK; | |
1805 | } | |
1806 | ||
bc92b956 | 1807 | static bool |
9b94a8fb | 1808 | rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned long nr_pages) |
7a8e76a3 | 1809 | { |
83f40318 VN |
1810 | struct list_head *tail_page, *to_remove, *next_page; |
1811 | struct buffer_page *to_remove_page, *tmp_iter_page; | |
1812 | struct buffer_page *last_page, *first_page; | |
9b94a8fb | 1813 | unsigned long nr_removed; |
83f40318 VN |
1814 | unsigned long head_bit; |
1815 | int page_entries; | |
1816 | ||
1817 | head_bit = 0; | |
7a8e76a3 | 1818 | |
5389f6fa | 1819 | raw_spin_lock_irq(&cpu_buffer->reader_lock); |
83f40318 VN |
1820 | atomic_inc(&cpu_buffer->record_disabled); |
1821 | /* | |
1822 | * We don't race with the readers since we have acquired the reader | |
1823 | * lock. We also don't race with writers after disabling recording. | |
1824 | * This makes it easy to figure out the first and the last page to be | |
1825 | * removed from the list. We unlink all the pages in between including | |
1826 | * the first and last pages. This is done in a busy loop so that we | |
1827 | * lose the least number of traces. | |
1828 | * The pages are freed after we restart recording and unlock readers. | |
1829 | */ | |
1830 | tail_page = &cpu_buffer->tail_page->list; | |
77ae365e | 1831 | |
83f40318 VN |
1832 | /* |
1833 | * tail page might be on reader page, we remove the next page | |
1834 | * from the ring buffer | |
1835 | */ | |
1836 | if (cpu_buffer->tail_page == cpu_buffer->reader_page) | |
1837 | tail_page = rb_list_head(tail_page->next); | |
1838 | to_remove = tail_page; | |
1839 | ||
1840 | /* start of pages to remove */ | |
1841 | first_page = list_entry(rb_list_head(to_remove->next), | |
1842 | struct buffer_page, list); | |
1843 | ||
1844 | for (nr_removed = 0; nr_removed < nr_pages; nr_removed++) { | |
1845 | to_remove = rb_list_head(to_remove)->next; | |
1846 | head_bit |= (unsigned long)to_remove & RB_PAGE_HEAD; | |
7a8e76a3 | 1847 | } |
2d093282 ZY |
1848 | /* Read iterators need to reset themselves when some pages removed */ |
1849 | cpu_buffer->pages_removed += nr_removed; | |
7a8e76a3 | 1850 | |
83f40318 | 1851 | next_page = rb_list_head(to_remove)->next; |
7a8e76a3 | 1852 | |
83f40318 VN |
1853 | /* |
1854 | * Now we remove all pages between tail_page and next_page. | |
1855 | * Make sure that we have head_bit value preserved for the | |
1856 | * next page | |
1857 | */ | |
1858 | tail_page->next = (struct list_head *)((unsigned long)next_page | | |
1859 | head_bit); | |
1860 | next_page = rb_list_head(next_page); | |
1861 | next_page->prev = tail_page; | |
1862 | ||
1863 | /* make sure pages points to a valid page in the ring buffer */ | |
1864 | cpu_buffer->pages = next_page; | |
1865 | ||
1866 | /* update head page */ | |
1867 | if (head_bit) | |
1868 | cpu_buffer->head_page = list_entry(next_page, | |
1869 | struct buffer_page, list); | |
1870 | ||
83f40318 VN |
1871 | /* pages are removed, resume tracing and then free the pages */ |
1872 | atomic_dec(&cpu_buffer->record_disabled); | |
5389f6fa | 1873 | raw_spin_unlock_irq(&cpu_buffer->reader_lock); |
83f40318 VN |
1874 | |
1875 | RB_WARN_ON(cpu_buffer, list_empty(cpu_buffer->pages)); | |
1876 | ||
1877 | /* last buffer page to remove */ | |
1878 | last_page = list_entry(rb_list_head(to_remove), struct buffer_page, | |
1879 | list); | |
1880 | tmp_iter_page = first_page; | |
1881 | ||
1882 | do { | |
83f36555 VN |
1883 | cond_resched(); |
1884 | ||
83f40318 | 1885 | to_remove_page = tmp_iter_page; |
6689bed3 | 1886 | rb_inc_page(&tmp_iter_page); |
83f40318 VN |
1887 | |
1888 | /* update the counters */ | |
1889 | page_entries = rb_page_entries(to_remove_page); | |
1890 | if (page_entries) { | |
1891 | /* | |
1892 | * If something was added to this page, it was full | |
1893 | * since it is not the tail page. So we deduct the | |
1894 | * bytes consumed in ring buffer from here. | |
48fdc72f | 1895 | * Increment overrun to account for the lost events. |
83f40318 | 1896 | */ |
48fdc72f | 1897 | local_add(page_entries, &cpu_buffer->overrun); |
45d99ea4 | 1898 | local_sub(rb_page_commit(to_remove_page), &cpu_buffer->entries_bytes); |
31029a8b | 1899 | local_inc(&cpu_buffer->pages_lost); |
83f40318 VN |
1900 | } |
1901 | ||
1902 | /* | |
1903 | * We have already removed references to this list item, just | |
1904 | * free up the buffer_page and its page | |
1905 | */ | |
1906 | free_buffer_page(to_remove_page); | |
1907 | nr_removed--; | |
1908 | ||
1909 | } while (to_remove_page != last_page); | |
1910 | ||
1911 | RB_WARN_ON(cpu_buffer, nr_removed); | |
5040b4b7 VN |
1912 | |
1913 | return nr_removed == 0; | |
7a8e76a3 SR |
1914 | } |
1915 | ||
bc92b956 | 1916 | static bool |
5040b4b7 | 1917 | rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 1918 | { |
5040b4b7 | 1919 | struct list_head *pages = &cpu_buffer->new_pages; |
88ca6a71 | 1920 | unsigned long flags; |
bc92b956 UB |
1921 | bool success; |
1922 | int retries; | |
7a8e76a3 | 1923 | |
88ca6a71 SR |
1924 | /* Can be called at early boot up, where interrupts must not been enabled */ |
1925 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
5040b4b7 VN |
1926 | /* |
1927 | * We are holding the reader lock, so the reader page won't be swapped | |
1928 | * in the ring buffer. Now we are racing with the writer trying to | |
1929 | * move head page and the tail page. | |
1930 | * We are going to adapt the reader page update process where: | |
1931 | * 1. We first splice the start and end of list of new pages between | |
1932 | * the head page and its previous page. | |
1933 | * 2. We cmpxchg the prev_page->next to point from head page to the | |
1934 | * start of new pages list. | |
1935 | * 3. Finally, we update the head->prev to the end of new list. | |
1936 | * | |
1937 | * We will try this process 10 times, to make sure that we don't keep | |
1938 | * spinning. | |
1939 | */ | |
1940 | retries = 10; | |
bc92b956 | 1941 | success = false; |
5040b4b7 | 1942 | while (retries--) { |
bdf4fb62 | 1943 | struct list_head *head_page, *prev_page; |
5040b4b7 VN |
1944 | struct list_head *last_page, *first_page; |
1945 | struct list_head *head_page_with_bit; | |
625ed527 | 1946 | struct buffer_page *hpage = rb_set_head_page(cpu_buffer); |
77ae365e | 1947 | |
625ed527 | 1948 | if (!hpage) |
54f7be5b | 1949 | break; |
625ed527 | 1950 | head_page = &hpage->list; |
5040b4b7 VN |
1951 | prev_page = head_page->prev; |
1952 | ||
1953 | first_page = pages->next; | |
1954 | last_page = pages->prev; | |
1955 | ||
1956 | head_page_with_bit = (struct list_head *) | |
1957 | ((unsigned long)head_page | RB_PAGE_HEAD); | |
1958 | ||
1959 | last_page->next = head_page_with_bit; | |
1960 | first_page->prev = prev_page; | |
1961 | ||
bdf4fb62 UB |
1962 | /* caution: head_page_with_bit gets updated on cmpxchg failure */ |
1963 | if (try_cmpxchg(&prev_page->next, | |
1964 | &head_page_with_bit, first_page)) { | |
5040b4b7 VN |
1965 | /* |
1966 | * yay, we replaced the page pointer to our new list, | |
1967 | * now, we just have to update to head page's prev | |
1968 | * pointer to point to end of list | |
1969 | */ | |
1970 | head_page->prev = last_page; | |
bc92b956 | 1971 | success = true; |
5040b4b7 VN |
1972 | break; |
1973 | } | |
7a8e76a3 | 1974 | } |
7a8e76a3 | 1975 | |
5040b4b7 VN |
1976 | if (success) |
1977 | INIT_LIST_HEAD(pages); | |
1978 | /* | |
1979 | * If we weren't successful in adding in new pages, warn and stop | |
1980 | * tracing | |
1981 | */ | |
1982 | RB_WARN_ON(cpu_buffer, !success); | |
88ca6a71 | 1983 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
5040b4b7 VN |
1984 | |
1985 | /* free pages if they weren't inserted */ | |
1986 | if (!success) { | |
1987 | struct buffer_page *bpage, *tmp; | |
1988 | list_for_each_entry_safe(bpage, tmp, &cpu_buffer->new_pages, | |
1989 | list) { | |
1990 | list_del_init(&bpage->list); | |
1991 | free_buffer_page(bpage); | |
1992 | } | |
1993 | } | |
1994 | return success; | |
7a8e76a3 SR |
1995 | } |
1996 | ||
83f40318 | 1997 | static void rb_update_pages(struct ring_buffer_per_cpu *cpu_buffer) |
438ced17 | 1998 | { |
bc92b956 | 1999 | bool success; |
5040b4b7 | 2000 | |
438ced17 | 2001 | if (cpu_buffer->nr_pages_to_update > 0) |
5040b4b7 | 2002 | success = rb_insert_pages(cpu_buffer); |
438ced17 | 2003 | else |
5040b4b7 VN |
2004 | success = rb_remove_pages(cpu_buffer, |
2005 | -cpu_buffer->nr_pages_to_update); | |
83f40318 | 2006 | |
5040b4b7 VN |
2007 | if (success) |
2008 | cpu_buffer->nr_pages += cpu_buffer->nr_pages_to_update; | |
83f40318 VN |
2009 | } |
2010 | ||
2011 | static void update_pages_handler(struct work_struct *work) | |
2012 | { | |
2013 | struct ring_buffer_per_cpu *cpu_buffer = container_of(work, | |
2014 | struct ring_buffer_per_cpu, update_pages_work); | |
2015 | rb_update_pages(cpu_buffer); | |
05fdd70d | 2016 | complete(&cpu_buffer->update_done); |
438ced17 VN |
2017 | } |
2018 | ||
7a8e76a3 SR |
2019 | /** |
2020 | * ring_buffer_resize - resize the ring buffer | |
2021 | * @buffer: the buffer to resize. | |
2022 | * @size: the new size. | |
d611851b | 2023 | * @cpu_id: the cpu buffer to resize |
7a8e76a3 | 2024 | * |
139f8400 | 2025 | * Minimum size is 2 * buffer->subbuf_size. |
7a8e76a3 | 2026 | * |
83f40318 | 2027 | * Returns 0 on success and < 0 on failure. |
7a8e76a3 | 2028 | */ |
13292494 | 2029 | int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, |
438ced17 | 2030 | int cpu_id) |
7a8e76a3 SR |
2031 | { |
2032 | struct ring_buffer_per_cpu *cpu_buffer; | |
9b94a8fb | 2033 | unsigned long nr_pages; |
0a1754b2 | 2034 | int cpu, err; |
7a8e76a3 | 2035 | |
ee51a1de IM |
2036 | /* |
2037 | * Always succeed at resizing a non-existent buffer: | |
2038 | */ | |
2039 | if (!buffer) | |
0a1754b2 | 2040 | return 0; |
ee51a1de | 2041 | |
6a31e1f1 SR |
2042 | /* Make sure the requested buffer exists */ |
2043 | if (cpu_id != RING_BUFFER_ALL_CPUS && | |
2044 | !cpumask_test_cpu(cpu_id, buffer->cpumask)) | |
0a1754b2 | 2045 | return 0; |
6a31e1f1 | 2046 | |
139f8400 | 2047 | nr_pages = DIV_ROUND_UP(size, buffer->subbuf_size); |
7a8e76a3 SR |
2048 | |
2049 | /* we need a minimum of two pages */ | |
59643d15 SRRH |
2050 | if (nr_pages < 2) |
2051 | nr_pages = 2; | |
7a8e76a3 | 2052 | |
83f40318 | 2053 | /* prevent another thread from changing buffer sizes */ |
7a8e76a3 | 2054 | mutex_lock(&buffer->mutex); |
8a96c028 | 2055 | atomic_inc(&buffer->resizing); |
07b8b10e | 2056 | |
438ced17 | 2057 | if (cpu_id == RING_BUFFER_ALL_CPUS) { |
07b8b10e SRV |
2058 | /* |
2059 | * Don't succeed if resizing is disabled, as a reader might be | |
2060 | * manipulating the ring buffer and is expecting a sane state while | |
2061 | * this is true. | |
2062 | */ | |
2063 | for_each_buffer_cpu(buffer, cpu) { | |
2064 | cpu_buffer = buffer->buffers[cpu]; | |
2065 | if (atomic_read(&cpu_buffer->resize_disabled)) { | |
2066 | err = -EBUSY; | |
2067 | goto out_err_unlock; | |
2068 | } | |
2069 | } | |
2070 | ||
438ced17 | 2071 | /* calculate the pages to update */ |
7a8e76a3 SR |
2072 | for_each_buffer_cpu(buffer, cpu) { |
2073 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 | 2074 | |
438ced17 VN |
2075 | cpu_buffer->nr_pages_to_update = nr_pages - |
2076 | cpu_buffer->nr_pages; | |
438ced17 VN |
2077 | /* |
2078 | * nothing more to do for removing pages or no update | |
2079 | */ | |
2080 | if (cpu_buffer->nr_pages_to_update <= 0) | |
2081 | continue; | |
d7ec4bfe | 2082 | /* |
438ced17 VN |
2083 | * to add pages, make sure all new pages can be |
2084 | * allocated without receiving ENOMEM | |
d7ec4bfe | 2085 | */ |
438ced17 | 2086 | INIT_LIST_HEAD(&cpu_buffer->new_pages); |
74e2afc6 QH |
2087 | if (__rb_allocate_pages(cpu_buffer, cpu_buffer->nr_pages_to_update, |
2088 | &cpu_buffer->new_pages)) { | |
438ced17 | 2089 | /* not enough memory for new pages */ |
83f40318 VN |
2090 | err = -ENOMEM; |
2091 | goto out_err; | |
2092 | } | |
f6bd2c92 ZY |
2093 | |
2094 | cond_resched(); | |
83f40318 VN |
2095 | } |
2096 | ||
99c37d1a | 2097 | cpus_read_lock(); |
83f40318 VN |
2098 | /* |
2099 | * Fire off all the required work handlers | |
05fdd70d | 2100 | * We can't schedule on offline CPUs, but it's not necessary |
83f40318 VN |
2101 | * since we can change their buffer sizes without any race. |
2102 | */ | |
2103 | for_each_buffer_cpu(buffer, cpu) { | |
2104 | cpu_buffer = buffer->buffers[cpu]; | |
05fdd70d | 2105 | if (!cpu_buffer->nr_pages_to_update) |
83f40318 VN |
2106 | continue; |
2107 | ||
021c5b34 CM |
2108 | /* Can't run something on an offline CPU. */ |
2109 | if (!cpu_online(cpu)) { | |
f5eb5588 SRRH |
2110 | rb_update_pages(cpu_buffer); |
2111 | cpu_buffer->nr_pages_to_update = 0; | |
2112 | } else { | |
88ca6a71 SR |
2113 | /* Run directly if possible. */ |
2114 | migrate_disable(); | |
2115 | if (cpu != smp_processor_id()) { | |
2116 | migrate_enable(); | |
2117 | schedule_work_on(cpu, | |
2118 | &cpu_buffer->update_pages_work); | |
2119 | } else { | |
2120 | update_pages_handler(&cpu_buffer->update_pages_work); | |
2121 | migrate_enable(); | |
2122 | } | |
f5eb5588 | 2123 | } |
7a8e76a3 | 2124 | } |
7a8e76a3 | 2125 | |
438ced17 VN |
2126 | /* wait for all the updates to complete */ |
2127 | for_each_buffer_cpu(buffer, cpu) { | |
2128 | cpu_buffer = buffer->buffers[cpu]; | |
05fdd70d | 2129 | if (!cpu_buffer->nr_pages_to_update) |
83f40318 VN |
2130 | continue; |
2131 | ||
05fdd70d VN |
2132 | if (cpu_online(cpu)) |
2133 | wait_for_completion(&cpu_buffer->update_done); | |
83f40318 | 2134 | cpu_buffer->nr_pages_to_update = 0; |
438ced17 | 2135 | } |
83f40318 | 2136 | |
99c37d1a | 2137 | cpus_read_unlock(); |
438ced17 VN |
2138 | } else { |
2139 | cpu_buffer = buffer->buffers[cpu_id]; | |
83f40318 | 2140 | |
438ced17 VN |
2141 | if (nr_pages == cpu_buffer->nr_pages) |
2142 | goto out; | |
7a8e76a3 | 2143 | |
07b8b10e SRV |
2144 | /* |
2145 | * Don't succeed if resizing is disabled, as a reader might be | |
2146 | * manipulating the ring buffer and is expecting a sane state while | |
2147 | * this is true. | |
2148 | */ | |
2149 | if (atomic_read(&cpu_buffer->resize_disabled)) { | |
2150 | err = -EBUSY; | |
2151 | goto out_err_unlock; | |
2152 | } | |
2153 | ||
438ced17 VN |
2154 | cpu_buffer->nr_pages_to_update = nr_pages - |
2155 | cpu_buffer->nr_pages; | |
2156 | ||
2157 | INIT_LIST_HEAD(&cpu_buffer->new_pages); | |
2158 | if (cpu_buffer->nr_pages_to_update > 0 && | |
74e2afc6 QH |
2159 | __rb_allocate_pages(cpu_buffer, cpu_buffer->nr_pages_to_update, |
2160 | &cpu_buffer->new_pages)) { | |
83f40318 VN |
2161 | err = -ENOMEM; |
2162 | goto out_err; | |
2163 | } | |
438ced17 | 2164 | |
99c37d1a | 2165 | cpus_read_lock(); |
83f40318 | 2166 | |
021c5b34 CM |
2167 | /* Can't run something on an offline CPU. */ |
2168 | if (!cpu_online(cpu_id)) | |
f5eb5588 SRRH |
2169 | rb_update_pages(cpu_buffer); |
2170 | else { | |
88ca6a71 SR |
2171 | /* Run directly if possible. */ |
2172 | migrate_disable(); | |
2173 | if (cpu_id == smp_processor_id()) { | |
2174 | rb_update_pages(cpu_buffer); | |
2175 | migrate_enable(); | |
2176 | } else { | |
2177 | migrate_enable(); | |
2178 | schedule_work_on(cpu_id, | |
2179 | &cpu_buffer->update_pages_work); | |
2180 | wait_for_completion(&cpu_buffer->update_done); | |
2181 | } | |
f5eb5588 | 2182 | } |
83f40318 | 2183 | |
83f40318 | 2184 | cpu_buffer->nr_pages_to_update = 0; |
99c37d1a | 2185 | cpus_read_unlock(); |
438ced17 | 2186 | } |
7a8e76a3 SR |
2187 | |
2188 | out: | |
659f451f SR |
2189 | /* |
2190 | * The ring buffer resize can happen with the ring buffer | |
2191 | * enabled, so that the update disturbs the tracing as little | |
2192 | * as possible. But if the buffer is disabled, we do not need | |
2193 | * to worry about that, and we can take the time to verify | |
2194 | * that the buffer is not corrupt. | |
2195 | */ | |
2196 | if (atomic_read(&buffer->record_disabled)) { | |
2197 | atomic_inc(&buffer->record_disabled); | |
2198 | /* | |
2199 | * Even though the buffer was disabled, we must make sure | |
2200 | * that it is truly disabled before calling rb_check_pages. | |
2201 | * There could have been a race between checking | |
2202 | * record_disable and incrementing it. | |
2203 | */ | |
74401729 | 2204 | synchronize_rcu(); |
659f451f | 2205 | for_each_buffer_cpu(buffer, cpu) { |
c2274b90 PP |
2206 | unsigned long flags; |
2207 | ||
659f451f | 2208 | cpu_buffer = buffer->buffers[cpu]; |
c2274b90 | 2209 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
659f451f | 2210 | rb_check_pages(cpu_buffer); |
c2274b90 | 2211 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
659f451f SR |
2212 | } |
2213 | atomic_dec(&buffer->record_disabled); | |
2214 | } | |
2215 | ||
8a96c028 | 2216 | atomic_dec(&buffer->resizing); |
7a8e76a3 | 2217 | mutex_unlock(&buffer->mutex); |
0a1754b2 | 2218 | return 0; |
7a8e76a3 | 2219 | |
83f40318 | 2220 | out_err: |
438ced17 VN |
2221 | for_each_buffer_cpu(buffer, cpu) { |
2222 | struct buffer_page *bpage, *tmp; | |
83f40318 | 2223 | |
438ced17 | 2224 | cpu_buffer = buffer->buffers[cpu]; |
438ced17 | 2225 | cpu_buffer->nr_pages_to_update = 0; |
83f40318 | 2226 | |
438ced17 VN |
2227 | if (list_empty(&cpu_buffer->new_pages)) |
2228 | continue; | |
83f40318 | 2229 | |
438ced17 VN |
2230 | list_for_each_entry_safe(bpage, tmp, &cpu_buffer->new_pages, |
2231 | list) { | |
2232 | list_del_init(&bpage->list); | |
2233 | free_buffer_page(bpage); | |
2234 | } | |
7a8e76a3 | 2235 | } |
07b8b10e | 2236 | out_err_unlock: |
8a96c028 | 2237 | atomic_dec(&buffer->resizing); |
641d2f63 | 2238 | mutex_unlock(&buffer->mutex); |
83f40318 | 2239 | return err; |
7a8e76a3 | 2240 | } |
c4f50183 | 2241 | EXPORT_SYMBOL_GPL(ring_buffer_resize); |
7a8e76a3 | 2242 | |
13292494 | 2243 | void ring_buffer_change_overwrite(struct trace_buffer *buffer, int val) |
750912fa DS |
2244 | { |
2245 | mutex_lock(&buffer->mutex); | |
2246 | if (val) | |
2247 | buffer->flags |= RB_FL_OVERWRITE; | |
2248 | else | |
2249 | buffer->flags &= ~RB_FL_OVERWRITE; | |
2250 | mutex_unlock(&buffer->mutex); | |
2251 | } | |
2252 | EXPORT_SYMBOL_GPL(ring_buffer_change_overwrite); | |
2253 | ||
2289d567 | 2254 | static __always_inline void *__rb_page_index(struct buffer_page *bpage, unsigned index) |
7a8e76a3 | 2255 | { |
044fa782 | 2256 | return bpage->page->data + index; |
7a8e76a3 SR |
2257 | } |
2258 | ||
2289d567 | 2259 | static __always_inline struct ring_buffer_event * |
d769041f | 2260 | rb_reader_event(struct ring_buffer_per_cpu *cpu_buffer) |
7a8e76a3 | 2261 | { |
6f807acd SR |
2262 | return __rb_page_index(cpu_buffer->reader_page, |
2263 | cpu_buffer->reader_page->read); | |
2264 | } | |
2265 | ||
785888c5 SRV |
2266 | static struct ring_buffer_event * |
2267 | rb_iter_head_event(struct ring_buffer_iter *iter) | |
bf41a158 | 2268 | { |
785888c5 SRV |
2269 | struct ring_buffer_event *event; |
2270 | struct buffer_page *iter_head_page = iter->head_page; | |
2271 | unsigned long commit; | |
2272 | unsigned length; | |
2273 | ||
153368ce SRV |
2274 | if (iter->head != iter->next_event) |
2275 | return iter->event; | |
2276 | ||
785888c5 SRV |
2277 | /* |
2278 | * When the writer goes across pages, it issues a cmpxchg which | |
2279 | * is a mb(), which will synchronize with the rmb here. | |
2280 | * (see rb_tail_page_update() and __rb_reserve_next()) | |
2281 | */ | |
2282 | commit = rb_page_commit(iter_head_page); | |
2283 | smp_rmb(); | |
95a404bd SRG |
2284 | |
2285 | /* An event needs to be at least 8 bytes in size */ | |
2286 | if (iter->head > commit - 8) | |
2287 | goto reset; | |
2288 | ||
785888c5 SRV |
2289 | event = __rb_page_index(iter_head_page, iter->head); |
2290 | length = rb_event_length(event); | |
2291 | ||
2292 | /* | |
2293 | * READ_ONCE() doesn't work on functions and we don't want the | |
2294 | * compiler doing any crazy optimizations with length. | |
2295 | */ | |
2296 | barrier(); | |
2297 | ||
139f8400 | 2298 | if ((iter->head + length) > commit || length > iter->event_size) |
785888c5 SRV |
2299 | /* Writer corrupted the read? */ |
2300 | goto reset; | |
2301 | ||
2302 | memcpy(iter->event, event, length); | |
2303 | /* | |
2304 | * If the page stamp is still the same after this rmb() then the | |
2305 | * event was safely copied without the writer entering the page. | |
2306 | */ | |
2307 | smp_rmb(); | |
2308 | ||
2309 | /* Make sure the page didn't change since we read this */ | |
2310 | if (iter->page_stamp != iter_head_page->page->time_stamp || | |
2311 | commit > rb_page_commit(iter_head_page)) | |
2312 | goto reset; | |
2313 | ||
2314 | iter->next_event = iter->head + length; | |
2315 | return iter->event; | |
2316 | reset: | |
2317 | /* Reset to the beginning */ | |
2318 | iter->page_stamp = iter->read_stamp = iter->head_page->page->time_stamp; | |
2319 | iter->head = 0; | |
2320 | iter->next_event = 0; | |
c9b7a4a7 | 2321 | iter->missed_events = 1; |
785888c5 | 2322 | return NULL; |
bf41a158 SR |
2323 | } |
2324 | ||
25985edc | 2325 | /* Size is determined by what has been committed */ |
2289d567 | 2326 | static __always_inline unsigned rb_page_size(struct buffer_page *bpage) |
bf41a158 | 2327 | { |
fe832be0 | 2328 | return rb_page_commit(bpage) & ~RB_MISSED_MASK; |
bf41a158 SR |
2329 | } |
2330 | ||
2289d567 | 2331 | static __always_inline unsigned |
bf41a158 SR |
2332 | rb_commit_index(struct ring_buffer_per_cpu *cpu_buffer) |
2333 | { | |
2334 | return rb_page_commit(cpu_buffer->commit_page); | |
2335 | } | |
2336 | ||
2289d567 | 2337 | static __always_inline unsigned |
3cb30911 | 2338 | rb_event_index(struct ring_buffer_per_cpu *cpu_buffer, struct ring_buffer_event *event) |
bf41a158 SR |
2339 | { |
2340 | unsigned long addr = (unsigned long)event; | |
2341 | ||
3cb30911 SRG |
2342 | addr &= (PAGE_SIZE << cpu_buffer->buffer->subbuf_order) - 1; |
2343 | ||
2344 | return addr - BUF_PAGE_HDR_SIZE; | |
bf41a158 SR |
2345 | } |
2346 | ||
34a148bf | 2347 | static void rb_inc_iter(struct ring_buffer_iter *iter) |
d769041f SR |
2348 | { |
2349 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
2350 | ||
2351 | /* | |
2352 | * The iterator could be on the reader page (it starts there). | |
2353 | * But the head could have moved, since the reader was | |
2354 | * found. Check for this case and assign the iterator | |
2355 | * to the head page instead of next. | |
2356 | */ | |
2357 | if (iter->head_page == cpu_buffer->reader_page) | |
77ae365e | 2358 | iter->head_page = rb_set_head_page(cpu_buffer); |
d769041f | 2359 | else |
6689bed3 | 2360 | rb_inc_page(&iter->head_page); |
d769041f | 2361 | |
28e3fc56 | 2362 | iter->page_stamp = iter->read_stamp = iter->head_page->page->time_stamp; |
7a8e76a3 | 2363 | iter->head = 0; |
785888c5 | 2364 | iter->next_event = 0; |
7a8e76a3 SR |
2365 | } |
2366 | ||
77ae365e SR |
2367 | /* |
2368 | * rb_handle_head_page - writer hit the head page | |
2369 | * | |
2370 | * Returns: +1 to retry page | |
2371 | * 0 to continue | |
2372 | * -1 on error | |
2373 | */ | |
2374 | static int | |
2375 | rb_handle_head_page(struct ring_buffer_per_cpu *cpu_buffer, | |
2376 | struct buffer_page *tail_page, | |
2377 | struct buffer_page *next_page) | |
2378 | { | |
2379 | struct buffer_page *new_head; | |
2380 | int entries; | |
2381 | int type; | |
2382 | int ret; | |
2383 | ||
2384 | entries = rb_page_entries(next_page); | |
2385 | ||
2386 | /* | |
2387 | * The hard part is here. We need to move the head | |
2388 | * forward, and protect against both readers on | |
2389 | * other CPUs and writers coming in via interrupts. | |
2390 | */ | |
2391 | type = rb_head_page_set_update(cpu_buffer, next_page, tail_page, | |
2392 | RB_PAGE_HEAD); | |
2393 | ||
2394 | /* | |
2395 | * type can be one of four: | |
2396 | * NORMAL - an interrupt already moved it for us | |
2397 | * HEAD - we are the first to get here. | |
2398 | * UPDATE - we are the interrupt interrupting | |
2399 | * a current move. | |
2400 | * MOVED - a reader on another CPU moved the next | |
2401 | * pointer to its reader page. Give up | |
2402 | * and try again. | |
2403 | */ | |
2404 | ||
2405 | switch (type) { | |
2406 | case RB_PAGE_HEAD: | |
2407 | /* | |
2408 | * We changed the head to UPDATE, thus | |
2409 | * it is our responsibility to update | |
2410 | * the counters. | |
2411 | */ | |
2412 | local_add(entries, &cpu_buffer->overrun); | |
45d99ea4 | 2413 | local_sub(rb_page_commit(next_page), &cpu_buffer->entries_bytes); |
31029a8b | 2414 | local_inc(&cpu_buffer->pages_lost); |
77ae365e SR |
2415 | |
2416 | /* | |
2417 | * The entries will be zeroed out when we move the | |
2418 | * tail page. | |
2419 | */ | |
2420 | ||
2421 | /* still more to do */ | |
2422 | break; | |
2423 | ||
2424 | case RB_PAGE_UPDATE: | |
2425 | /* | |
2426 | * This is an interrupt that interrupt the | |
2427 | * previous update. Still more to do. | |
2428 | */ | |
2429 | break; | |
2430 | case RB_PAGE_NORMAL: | |
2431 | /* | |
2432 | * An interrupt came in before the update | |
2433 | * and processed this for us. | |
2434 | * Nothing left to do. | |
2435 | */ | |
2436 | return 1; | |
2437 | case RB_PAGE_MOVED: | |
2438 | /* | |
2439 | * The reader is on another CPU and just did | |
2440 | * a swap with our next_page. | |
2441 | * Try again. | |
2442 | */ | |
2443 | return 1; | |
2444 | default: | |
2445 | RB_WARN_ON(cpu_buffer, 1); /* WTF??? */ | |
2446 | return -1; | |
2447 | } | |
2448 | ||
2449 | /* | |
2450 | * Now that we are here, the old head pointer is | |
2451 | * set to UPDATE. This will keep the reader from | |
2452 | * swapping the head page with the reader page. | |
2453 | * The reader (on another CPU) will spin till | |
2454 | * we are finished. | |
2455 | * | |
2456 | * We just need to protect against interrupts | |
2457 | * doing the job. We will set the next pointer | |
2458 | * to HEAD. After that, we set the old pointer | |
2459 | * to NORMAL, but only if it was HEAD before. | |
2460 | * otherwise we are an interrupt, and only | |
2461 | * want the outer most commit to reset it. | |
2462 | */ | |
2463 | new_head = next_page; | |
6689bed3 | 2464 | rb_inc_page(&new_head); |
77ae365e SR |
2465 | |
2466 | ret = rb_head_page_set_head(cpu_buffer, new_head, next_page, | |
2467 | RB_PAGE_NORMAL); | |
2468 | ||
2469 | /* | |
2470 | * Valid returns are: | |
2471 | * HEAD - an interrupt came in and already set it. | |
2472 | * NORMAL - One of two things: | |
2473 | * 1) We really set it. | |
2474 | * 2) A bunch of interrupts came in and moved | |
2475 | * the page forward again. | |
2476 | */ | |
2477 | switch (ret) { | |
2478 | case RB_PAGE_HEAD: | |
2479 | case RB_PAGE_NORMAL: | |
2480 | /* OK */ | |
2481 | break; | |
2482 | default: | |
2483 | RB_WARN_ON(cpu_buffer, 1); | |
2484 | return -1; | |
2485 | } | |
2486 | ||
2487 | /* | |
2488 | * It is possible that an interrupt came in, | |
2489 | * set the head up, then more interrupts came in | |
2490 | * and moved it again. When we get back here, | |
2491 | * the page would have been set to NORMAL but we | |
2492 | * just set it back to HEAD. | |
2493 | * | |
2494 | * How do you detect this? Well, if that happened | |
2495 | * the tail page would have moved. | |
2496 | */ | |
2497 | if (ret == RB_PAGE_NORMAL) { | |
8573636e SRRH |
2498 | struct buffer_page *buffer_tail_page; |
2499 | ||
2500 | buffer_tail_page = READ_ONCE(cpu_buffer->tail_page); | |
77ae365e SR |
2501 | /* |
2502 | * If the tail had moved passed next, then we need | |
2503 | * to reset the pointer. | |
2504 | */ | |
8573636e SRRH |
2505 | if (buffer_tail_page != tail_page && |
2506 | buffer_tail_page != next_page) | |
77ae365e SR |
2507 | rb_head_page_set_normal(cpu_buffer, new_head, |
2508 | next_page, | |
2509 | RB_PAGE_HEAD); | |
2510 | } | |
2511 | ||
2512 | /* | |
2513 | * If this was the outer most commit (the one that | |
2514 | * changed the original pointer from HEAD to UPDATE), | |
2515 | * then it is up to us to reset it to NORMAL. | |
2516 | */ | |
2517 | if (type == RB_PAGE_HEAD) { | |
2518 | ret = rb_head_page_set_normal(cpu_buffer, next_page, | |
2519 | tail_page, | |
2520 | RB_PAGE_UPDATE); | |
2521 | if (RB_WARN_ON(cpu_buffer, | |
2522 | ret != RB_PAGE_UPDATE)) | |
2523 | return -1; | |
2524 | } | |
2525 | ||
2526 | return 0; | |
2527 | } | |
2528 | ||
c7b09308 SR |
2529 | static inline void |
2530 | rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer, | |
fcc742ea | 2531 | unsigned long tail, struct rb_event_info *info) |
c7b09308 | 2532 | { |
139f8400 | 2533 | unsigned long bsize = READ_ONCE(cpu_buffer->buffer->subbuf_size); |
fcc742ea | 2534 | struct buffer_page *tail_page = info->tail_page; |
c7b09308 | 2535 | struct ring_buffer_event *event; |
fcc742ea | 2536 | unsigned long length = info->length; |
c7b09308 SR |
2537 | |
2538 | /* | |
2539 | * Only the event that crossed the page boundary | |
2540 | * must fill the old tail_page with padding. | |
2541 | */ | |
139f8400 | 2542 | if (tail >= bsize) { |
b3230c8b SR |
2543 | /* |
2544 | * If the page was filled, then we still need | |
2545 | * to update the real_end. Reset it to zero | |
2546 | * and the reader will ignore it. | |
2547 | */ | |
139f8400 | 2548 | if (tail == bsize) |
b3230c8b SR |
2549 | tail_page->real_end = 0; |
2550 | ||
c7b09308 SR |
2551 | local_sub(length, &tail_page->write); |
2552 | return; | |
2553 | } | |
2554 | ||
2555 | event = __rb_page_index(tail_page, tail); | |
2556 | ||
ff0ff84a SR |
2557 | /* |
2558 | * Save the original length to the meta data. | |
2559 | * This will be used by the reader to add lost event | |
2560 | * counter. | |
2561 | */ | |
2562 | tail_page->real_end = tail; | |
2563 | ||
c7b09308 SR |
2564 | /* |
2565 | * If this event is bigger than the minimum size, then | |
2566 | * we need to be careful that we don't subtract the | |
2567 | * write counter enough to allow another writer to slip | |
2568 | * in on this page. | |
2569 | * We put in a discarded commit instead, to make sure | |
45d99ea4 ZY |
2570 | * that this space is not used again, and this space will |
2571 | * not be accounted into 'entries_bytes'. | |
c7b09308 SR |
2572 | * |
2573 | * If we are less than the minimum size, we don't need to | |
2574 | * worry about it. | |
2575 | */ | |
139f8400 | 2576 | if (tail > (bsize - RB_EVNT_MIN_SIZE)) { |
c7b09308 SR |
2577 | /* No room for any events */ |
2578 | ||
2579 | /* Mark the rest of the page with padding */ | |
2580 | rb_event_set_padding(event); | |
2581 | ||
a0fcaaed SRG |
2582 | /* Make sure the padding is visible before the write update */ |
2583 | smp_wmb(); | |
2584 | ||
c7b09308 SR |
2585 | /* Set the write back to the previous setting */ |
2586 | local_sub(length, &tail_page->write); | |
2587 | return; | |
2588 | } | |
2589 | ||
2590 | /* Put in a discarded event */ | |
139f8400 | 2591 | event->array[0] = (bsize - tail) - RB_EVNT_HDR_SIZE; |
c7b09308 SR |
2592 | event->type_len = RINGBUF_TYPE_PADDING; |
2593 | /* time delta must be non zero */ | |
2594 | event->time_delta = 1; | |
c7b09308 | 2595 | |
45d99ea4 | 2596 | /* account for padding bytes */ |
139f8400 | 2597 | local_add(bsize - tail, &cpu_buffer->entries_bytes); |
45d99ea4 | 2598 | |
a0fcaaed SRG |
2599 | /* Make sure the padding is visible before the tail_page->write update */ |
2600 | smp_wmb(); | |
2601 | ||
c7b09308 | 2602 | /* Set write to end of buffer */ |
139f8400 | 2603 | length = (tail + length) - bsize; |
c7b09308 SR |
2604 | local_sub(length, &tail_page->write); |
2605 | } | |
6634ff26 | 2606 | |
4239c38f SRRH |
2607 | static inline void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer); |
2608 | ||
747e94ae SR |
2609 | /* |
2610 | * This is the slow path, force gcc not to inline it. | |
2611 | */ | |
2612 | static noinline struct ring_buffer_event * | |
6634ff26 | 2613 | rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer, |
fcc742ea | 2614 | unsigned long tail, struct rb_event_info *info) |
7a8e76a3 | 2615 | { |
fcc742ea | 2616 | struct buffer_page *tail_page = info->tail_page; |
5a50e33c | 2617 | struct buffer_page *commit_page = cpu_buffer->commit_page; |
13292494 | 2618 | struct trace_buffer *buffer = cpu_buffer->buffer; |
77ae365e SR |
2619 | struct buffer_page *next_page; |
2620 | int ret; | |
aa20ae84 SR |
2621 | |
2622 | next_page = tail_page; | |
2623 | ||
6689bed3 | 2624 | rb_inc_page(&next_page); |
aa20ae84 | 2625 | |
aa20ae84 SR |
2626 | /* |
2627 | * If for some reason, we had an interrupt storm that made | |
2628 | * it all the way around the buffer, bail, and warn | |
2629 | * about it. | |
2630 | */ | |
2631 | if (unlikely(next_page == commit_page)) { | |
77ae365e | 2632 | local_inc(&cpu_buffer->commit_overrun); |
aa20ae84 SR |
2633 | goto out_reset; |
2634 | } | |
2635 | ||
77ae365e SR |
2636 | /* |
2637 | * This is where the fun begins! | |
2638 | * | |
2639 | * We are fighting against races between a reader that | |
2640 | * could be on another CPU trying to swap its reader | |
2641 | * page with the buffer head. | |
2642 | * | |
2643 | * We are also fighting against interrupts coming in and | |
2644 | * moving the head or tail on us as well. | |
2645 | * | |
2646 | * If the next page is the head page then we have filled | |
2647 | * the buffer, unless the commit page is still on the | |
2648 | * reader page. | |
2649 | */ | |
6689bed3 | 2650 | if (rb_is_head_page(next_page, &tail_page->list)) { |
aa20ae84 | 2651 | |
77ae365e SR |
2652 | /* |
2653 | * If the commit is not on the reader page, then | |
2654 | * move the header page. | |
2655 | */ | |
2656 | if (!rb_is_reader_page(cpu_buffer->commit_page)) { | |
2657 | /* | |
2658 | * If we are not in overwrite mode, | |
2659 | * this is easy, just stop here. | |
2660 | */ | |
884bfe89 SP |
2661 | if (!(buffer->flags & RB_FL_OVERWRITE)) { |
2662 | local_inc(&cpu_buffer->dropped_events); | |
77ae365e | 2663 | goto out_reset; |
884bfe89 | 2664 | } |
77ae365e SR |
2665 | |
2666 | ret = rb_handle_head_page(cpu_buffer, | |
2667 | tail_page, | |
2668 | next_page); | |
2669 | if (ret < 0) | |
2670 | goto out_reset; | |
2671 | if (ret) | |
2672 | goto out_again; | |
2673 | } else { | |
2674 | /* | |
2675 | * We need to be careful here too. The | |
2676 | * commit page could still be on the reader | |
2677 | * page. We could have a small buffer, and | |
2678 | * have filled up the buffer with events | |
2679 | * from interrupts and such, and wrapped. | |
2680 | * | |
c6358bac | 2681 | * Note, if the tail page is also on the |
77ae365e SR |
2682 | * reader_page, we let it move out. |
2683 | */ | |
2684 | if (unlikely((cpu_buffer->commit_page != | |
2685 | cpu_buffer->tail_page) && | |
2686 | (cpu_buffer->commit_page == | |
2687 | cpu_buffer->reader_page))) { | |
2688 | local_inc(&cpu_buffer->commit_overrun); | |
2689 | goto out_reset; | |
2690 | } | |
aa20ae84 SR |
2691 | } |
2692 | } | |
2693 | ||
70004986 | 2694 | rb_tail_page_update(cpu_buffer, tail_page, next_page); |
aa20ae84 | 2695 | |
77ae365e | 2696 | out_again: |
aa20ae84 | 2697 | |
fcc742ea | 2698 | rb_reset_tail(cpu_buffer, tail, info); |
aa20ae84 | 2699 | |
4239c38f SRRH |
2700 | /* Commit what we have for now. */ |
2701 | rb_end_commit(cpu_buffer); | |
2702 | /* rb_end_commit() decs committing */ | |
2703 | local_inc(&cpu_buffer->committing); | |
2704 | ||
aa20ae84 SR |
2705 | /* fail and let the caller try again */ |
2706 | return ERR_PTR(-EAGAIN); | |
2707 | ||
45141d46 | 2708 | out_reset: |
6f3b3440 | 2709 | /* reset write */ |
fcc742ea | 2710 | rb_reset_tail(cpu_buffer, tail, info); |
6f3b3440 | 2711 | |
bf41a158 | 2712 | return NULL; |
7a8e76a3 SR |
2713 | } |
2714 | ||
74e87937 SRV |
2715 | /* Slow path */ |
2716 | static struct ring_buffer_event * | |
3cb30911 SRG |
2717 | rb_add_time_stamp(struct ring_buffer_per_cpu *cpu_buffer, |
2718 | struct ring_buffer_event *event, u64 delta, bool abs) | |
9826b273 | 2719 | { |
dc4e2801 TZ |
2720 | if (abs) |
2721 | event->type_len = RINGBUF_TYPE_TIME_STAMP; | |
2722 | else | |
2723 | event->type_len = RINGBUF_TYPE_TIME_EXTEND; | |
9826b273 | 2724 | |
dc4e2801 | 2725 | /* Not the first event on the page, or not delta? */ |
3cb30911 | 2726 | if (abs || rb_event_index(cpu_buffer, event)) { |
d90fd774 SRRH |
2727 | event->time_delta = delta & TS_MASK; |
2728 | event->array[0] = delta >> TS_SHIFT; | |
2729 | } else { | |
2730 | /* nope, just zero it */ | |
2731 | event->time_delta = 0; | |
2732 | event->array[0] = 0; | |
2733 | } | |
a4543a2f | 2734 | |
d90fd774 SRRH |
2735 | return skip_time_extend(event); |
2736 | } | |
a4543a2f | 2737 | |
58fbc3c6 SRV |
2738 | #ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK |
2739 | static inline bool sched_clock_stable(void) | |
2740 | { | |
2741 | return true; | |
2742 | } | |
2743 | #endif | |
2744 | ||
74e87937 | 2745 | static void |
58fbc3c6 SRV |
2746 | rb_check_timestamp(struct ring_buffer_per_cpu *cpu_buffer, |
2747 | struct rb_event_info *info) | |
2748 | { | |
2749 | u64 write_stamp; | |
2750 | ||
29ce2451 | 2751 | WARN_ONCE(1, "Delta way too big! %llu ts=%llu before=%llu after=%llu write stamp=%llu\n%s", |
58fbc3c6 SRV |
2752 | (unsigned long long)info->delta, |
2753 | (unsigned long long)info->ts, | |
2754 | (unsigned long long)info->before, | |
2755 | (unsigned long long)info->after, | |
c84897c0 | 2756 | (unsigned long long)({rb_time_read(&cpu_buffer->write_stamp, &write_stamp); write_stamp;}), |
58fbc3c6 SRV |
2757 | sched_clock_stable() ? "" : |
2758 | "If you just came from a suspend/resume,\n" | |
2759 | "please switch to the trace global clock:\n" | |
2455f0e1 | 2760 | " echo global > /sys/kernel/tracing/trace_clock\n" |
58fbc3c6 SRV |
2761 | "or add trace_clock=global to the kernel command line\n"); |
2762 | } | |
2763 | ||
74e87937 SRV |
2764 | static void rb_add_timestamp(struct ring_buffer_per_cpu *cpu_buffer, |
2765 | struct ring_buffer_event **event, | |
2766 | struct rb_event_info *info, | |
2767 | u64 *delta, | |
2768 | unsigned int *length) | |
2769 | { | |
2770 | bool abs = info->add_timestamp & | |
2771 | (RB_ADD_STAMP_FORCE | RB_ADD_STAMP_ABSOLUTE); | |
2772 | ||
29ce2451 | 2773 | if (unlikely(info->delta > (1ULL << 59))) { |
6695da58 SRG |
2774 | /* |
2775 | * Some timers can use more than 59 bits, and when a timestamp | |
2776 | * is added to the buffer, it will lose those bits. | |
2777 | */ | |
2778 | if (abs && (info->ts & TS_MSB)) { | |
2779 | info->delta &= ABS_TS_MASK; | |
2780 | ||
29ce2451 | 2781 | /* did the clock go backwards */ |
6695da58 | 2782 | } else if (info->before == info->after && info->before > info->ts) { |
29ce2451 SRV |
2783 | /* not interrupted */ |
2784 | static int once; | |
2785 | ||
2786 | /* | |
2787 | * This is possible with a recalibrating of the TSC. | |
2788 | * Do not produce a call stack, but just report it. | |
2789 | */ | |
2790 | if (!once) { | |
2791 | once++; | |
2792 | pr_warn("Ring buffer clock went backwards: %llu -> %llu\n", | |
2793 | info->before, info->ts); | |
2794 | } | |
2795 | } else | |
2796 | rb_check_timestamp(cpu_buffer, info); | |
2797 | if (!abs) | |
2798 | info->delta = 0; | |
2799 | } | |
3cb30911 | 2800 | *event = rb_add_time_stamp(cpu_buffer, *event, info->delta, abs); |
74e87937 SRV |
2801 | *length -= RB_LEN_TIME_EXTEND; |
2802 | *delta = 0; | |
2803 | } | |
2804 | ||
d90fd774 SRRH |
2805 | /** |
2806 | * rb_update_event - update event type and data | |
cfc585a4 | 2807 | * @cpu_buffer: The per cpu buffer of the @event |
d90fd774 | 2808 | * @event: the event to update |
cfc585a4 | 2809 | * @info: The info to update the @event with (contains length and delta) |
d90fd774 | 2810 | * |
cfc585a4 | 2811 | * Update the type and data fields of the @event. The length |
d90fd774 SRRH |
2812 | * is the actual size that is written to the ring buffer, |
2813 | * and with this, we can determine what to place into the | |
2814 | * data field. | |
2815 | */ | |
b7dc42fd | 2816 | static void |
d90fd774 SRRH |
2817 | rb_update_event(struct ring_buffer_per_cpu *cpu_buffer, |
2818 | struct ring_buffer_event *event, | |
2819 | struct rb_event_info *info) | |
2820 | { | |
2821 | unsigned length = info->length; | |
2822 | u64 delta = info->delta; | |
8672e494 SRV |
2823 | unsigned int nest = local_read(&cpu_buffer->committing) - 1; |
2824 | ||
a948c69d | 2825 | if (!WARN_ON_ONCE(nest >= MAX_NEST)) |
8672e494 | 2826 | cpu_buffer->event_stamp[nest] = info->ts; |
a4543a2f SRRH |
2827 | |
2828 | /* | |
d90fd774 | 2829 | * If we need to add a timestamp, then we |
6167c205 | 2830 | * add it to the start of the reserved space. |
a4543a2f | 2831 | */ |
74e87937 SRV |
2832 | if (unlikely(info->add_timestamp)) |
2833 | rb_add_timestamp(cpu_buffer, &event, info, &delta, &length); | |
a4543a2f | 2834 | |
d90fd774 SRRH |
2835 | event->time_delta = delta; |
2836 | length -= RB_EVNT_HDR_SIZE; | |
adab66b7 | 2837 | if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) { |
d90fd774 SRRH |
2838 | event->type_len = 0; |
2839 | event->array[0] = length; | |
2840 | } else | |
2841 | event->type_len = DIV_ROUND_UP(length, RB_ALIGNMENT); | |
2842 | } | |
2843 | ||
2844 | static unsigned rb_calculate_event_length(unsigned length) | |
2845 | { | |
2846 | struct ring_buffer_event event; /* Used only for sizeof array */ | |
2847 | ||
2848 | /* zero length can cause confusions */ | |
2849 | if (!length) | |
2850 | length++; | |
2851 | ||
adab66b7 | 2852 | if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) |
d90fd774 SRRH |
2853 | length += sizeof(event.array[0]); |
2854 | ||
2855 | length += RB_EVNT_HDR_SIZE; | |
adab66b7 | 2856 | length = ALIGN(length, RB_ARCH_ALIGNMENT); |
d90fd774 SRRH |
2857 | |
2858 | /* | |
2859 | * In case the time delta is larger than the 27 bits for it | |
2860 | * in the header, we need to add a timestamp. If another | |
2861 | * event comes in when trying to discard this one to increase | |
2862 | * the length, then the timestamp will be added in the allocated | |
2863 | * space of this event. If length is bigger than the size needed | |
2864 | * for the TIME_EXTEND, then padding has to be used. The events | |
2865 | * length must be either RB_LEN_TIME_EXTEND, or greater than or equal | |
2866 | * to RB_LEN_TIME_EXTEND + 8, as 8 is the minimum size for padding. | |
2867 | * As length is a multiple of 4, we only need to worry if it | |
2868 | * is 12 (RB_LEN_TIME_EXTEND + 4). | |
2869 | */ | |
2870 | if (length == RB_LEN_TIME_EXTEND + RB_ALIGNMENT) | |
2871 | length += RB_ALIGNMENT; | |
2872 | ||
2873 | return length; | |
2874 | } | |
2875 | ||
bc92b956 | 2876 | static inline bool |
d90fd774 SRRH |
2877 | rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer, |
2878 | struct ring_buffer_event *event) | |
2879 | { | |
2880 | unsigned long new_index, old_index; | |
2881 | struct buffer_page *bpage; | |
d90fd774 SRRH |
2882 | unsigned long addr; |
2883 | ||
3cb30911 | 2884 | new_index = rb_event_index(cpu_buffer, event); |
d90fd774 SRRH |
2885 | old_index = new_index + rb_event_ts_length(event); |
2886 | addr = (unsigned long)event; | |
3cb30911 | 2887 | addr &= ~((PAGE_SIZE << cpu_buffer->buffer->subbuf_order) - 1); |
d90fd774 | 2888 | |
8573636e | 2889 | bpage = READ_ONCE(cpu_buffer->tail_page); |
d90fd774 | 2890 | |
083e9f65 SRG |
2891 | /* |
2892 | * Make sure the tail_page is still the same and | |
2893 | * the next write location is the end of this event | |
2894 | */ | |
d90fd774 SRRH |
2895 | if (bpage->page == (void *)addr && rb_page_write(bpage) == old_index) { |
2896 | unsigned long write_mask = | |
2897 | local_read(&bpage->write) & ~RB_WRITE_MASK; | |
2898 | unsigned long event_length = rb_event_length(event); | |
a389d86f | 2899 | |
b2dd7975 SRG |
2900 | /* |
2901 | * For the before_stamp to be different than the write_stamp | |
2902 | * to make sure that the next event adds an absolute | |
2903 | * value and does not rely on the saved write stamp, which | |
2904 | * is now going to be bogus. | |
083e9f65 SRG |
2905 | * |
2906 | * By setting the before_stamp to zero, the next event | |
2907 | * is not going to use the write_stamp and will instead | |
2908 | * create an absolute timestamp. This means there's no | |
2909 | * reason to update the wirte_stamp! | |
b2dd7975 SRG |
2910 | */ |
2911 | rb_time_set(&cpu_buffer->before_stamp, 0); | |
2912 | ||
a389d86f SRV |
2913 | /* |
2914 | * If an event were to come in now, it would see that the | |
2915 | * write_stamp and the before_stamp are different, and assume | |
2916 | * that this event just added itself before updating | |
2917 | * the write stamp. The interrupting event will fix the | |
083e9f65 | 2918 | * write stamp for us, and use an absolute timestamp. |
a389d86f SRV |
2919 | */ |
2920 | ||
d90fd774 SRRH |
2921 | /* |
2922 | * This is on the tail page. It is possible that | |
2923 | * a write could come in and move the tail page | |
2924 | * and write to the next page. That is fine | |
2925 | * because we just shorten what is on this page. | |
2926 | */ | |
2927 | old_index += write_mask; | |
2928 | new_index += write_mask; | |
00a8478f UB |
2929 | |
2930 | /* caution: old_index gets updated on cmpxchg failure */ | |
2931 | if (local_try_cmpxchg(&bpage->write, &old_index, new_index)) { | |
d90fd774 SRRH |
2932 | /* update counters */ |
2933 | local_sub(event_length, &cpu_buffer->entries_bytes); | |
bc92b956 | 2934 | return true; |
d90fd774 SRRH |
2935 | } |
2936 | } | |
2937 | ||
2938 | /* could not discard */ | |
bc92b956 | 2939 | return false; |
d90fd774 SRRH |
2940 | } |
2941 | ||
2942 | static void rb_start_commit(struct ring_buffer_per_cpu *cpu_buffer) | |
2943 | { | |
2944 | local_inc(&cpu_buffer->committing); | |
2945 | local_inc(&cpu_buffer->commits); | |
2946 | } | |
2947 | ||
38e11df1 | 2948 | static __always_inline void |
d90fd774 SRRH |
2949 | rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) |
2950 | { | |
2951 | unsigned long max_count; | |
2952 | ||
2953 | /* | |
2954 | * We only race with interrupts and NMIs on this CPU. | |
2955 | * If we own the commit event, then we can commit | |
2956 | * all others that interrupted us, since the interruptions | |
2957 | * are in stack format (they finish before they come | |
2958 | * back to us). This allows us to do a simple loop to | |
2959 | * assign the commit to the tail. | |
2960 | */ | |
2961 | again: | |
2962 | max_count = cpu_buffer->nr_pages * 100; | |
2963 | ||
8573636e | 2964 | while (cpu_buffer->commit_page != READ_ONCE(cpu_buffer->tail_page)) { |
d90fd774 SRRH |
2965 | if (RB_WARN_ON(cpu_buffer, !(--max_count))) |
2966 | return; | |
2967 | if (RB_WARN_ON(cpu_buffer, | |
2968 | rb_is_reader_page(cpu_buffer->tail_page))) | |
2969 | return; | |
6455b616 ZY |
2970 | /* |
2971 | * No need for a memory barrier here, as the update | |
2972 | * of the tail_page did it for this page. | |
2973 | */ | |
d90fd774 SRRH |
2974 | local_set(&cpu_buffer->commit_page->page->commit, |
2975 | rb_page_write(cpu_buffer->commit_page)); | |
6689bed3 | 2976 | rb_inc_page(&cpu_buffer->commit_page); |
d90fd774 SRRH |
2977 | /* add barrier to keep gcc from optimizing too much */ |
2978 | barrier(); | |
2979 | } | |
2980 | while (rb_commit_index(cpu_buffer) != | |
2981 | rb_page_write(cpu_buffer->commit_page)) { | |
2982 | ||
6455b616 ZY |
2983 | /* Make sure the readers see the content of what is committed. */ |
2984 | smp_wmb(); | |
d90fd774 SRRH |
2985 | local_set(&cpu_buffer->commit_page->page->commit, |
2986 | rb_page_write(cpu_buffer->commit_page)); | |
2987 | RB_WARN_ON(cpu_buffer, | |
2988 | local_read(&cpu_buffer->commit_page->page->commit) & | |
2989 | ~RB_WRITE_MASK); | |
2990 | barrier(); | |
2991 | } | |
2992 | ||
2993 | /* again, keep gcc from optimizing */ | |
2994 | barrier(); | |
2995 | ||
2996 | /* | |
2997 | * If an interrupt came in just after the first while loop | |
2998 | * and pushed the tail page forward, we will be left with | |
2999 | * a dangling commit that will never go forward. | |
3000 | */ | |
8573636e | 3001 | if (unlikely(cpu_buffer->commit_page != READ_ONCE(cpu_buffer->tail_page))) |
d90fd774 SRRH |
3002 | goto again; |
3003 | } | |
3004 | ||
38e11df1 | 3005 | static __always_inline void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer) |
d90fd774 SRRH |
3006 | { |
3007 | unsigned long commits; | |
3008 | ||
3009 | if (RB_WARN_ON(cpu_buffer, | |
3010 | !local_read(&cpu_buffer->committing))) | |
3011 | return; | |
3012 | ||
3013 | again: | |
3014 | commits = local_read(&cpu_buffer->commits); | |
3015 | /* synchronize with interrupts */ | |
3016 | barrier(); | |
3017 | if (local_read(&cpu_buffer->committing) == 1) | |
3018 | rb_set_commit_to_write(cpu_buffer); | |
3019 | ||
3020 | local_dec(&cpu_buffer->committing); | |
3021 | ||
3022 | /* synchronize with interrupts */ | |
3023 | barrier(); | |
3024 | ||
3025 | /* | |
3026 | * Need to account for interrupts coming in between the | |
3027 | * updating of the commit page and the clearing of the | |
3028 | * committing counter. | |
3029 | */ | |
3030 | if (unlikely(local_read(&cpu_buffer->commits) != commits) && | |
3031 | !local_read(&cpu_buffer->committing)) { | |
3032 | local_inc(&cpu_buffer->committing); | |
3033 | goto again; | |
3034 | } | |
3035 | } | |
3036 | ||
3037 | static inline void rb_event_discard(struct ring_buffer_event *event) | |
3038 | { | |
dc4e2801 | 3039 | if (extended_time(event)) |
d90fd774 SRRH |
3040 | event = skip_time_extend(event); |
3041 | ||
3042 | /* array[0] holds the actual length for the discarded event */ | |
3043 | event->array[0] = rb_event_data_length(event) - RB_EVNT_HDR_SIZE; | |
3044 | event->type_len = RINGBUF_TYPE_PADDING; | |
3045 | /* time delta must be non zero */ | |
3046 | if (!event->time_delta) | |
3047 | event->time_delta = 1; | |
3048 | } | |
3049 | ||
04aabc32 | 3050 | static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer) |
d90fd774 SRRH |
3051 | { |
3052 | local_inc(&cpu_buffer->entries); | |
d90fd774 SRRH |
3053 | rb_end_commit(cpu_buffer); |
3054 | } | |
3055 | ||
3056 | static __always_inline void | |
13292494 | 3057 | rb_wakeups(struct trace_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer) |
d90fd774 | 3058 | { |
d90fd774 SRRH |
3059 | if (buffer->irq_work.waiters_pending) { |
3060 | buffer->irq_work.waiters_pending = false; | |
3061 | /* irq_work_queue() supplies it's own memory barriers */ | |
3062 | irq_work_queue(&buffer->irq_work.work); | |
3063 | } | |
3064 | ||
3065 | if (cpu_buffer->irq_work.waiters_pending) { | |
3066 | cpu_buffer->irq_work.waiters_pending = false; | |
3067 | /* irq_work_queue() supplies it's own memory barriers */ | |
3068 | irq_work_queue(&cpu_buffer->irq_work.work); | |
3069 | } | |
3070 | ||
03329f99 SRV |
3071 | if (cpu_buffer->last_pages_touch == local_read(&cpu_buffer->pages_touched)) |
3072 | return; | |
d90fd774 | 3073 | |
03329f99 SRV |
3074 | if (cpu_buffer->reader_page == cpu_buffer->commit_page) |
3075 | return; | |
2c2b0a78 | 3076 | |
03329f99 SRV |
3077 | if (!cpu_buffer->irq_work.full_waiters_pending) |
3078 | return; | |
2c2b0a78 | 3079 | |
03329f99 SRV |
3080 | cpu_buffer->last_pages_touch = local_read(&cpu_buffer->pages_touched); |
3081 | ||
42fb0a1e | 3082 | if (!full_hit(buffer, cpu_buffer->cpu, cpu_buffer->shortest_full)) |
03329f99 SRV |
3083 | return; |
3084 | ||
3085 | cpu_buffer->irq_work.wakeup_full = true; | |
3086 | cpu_buffer->irq_work.full_waiters_pending = false; | |
3087 | /* irq_work_queue() supplies it's own memory barriers */ | |
3088 | irq_work_queue(&cpu_buffer->irq_work.work); | |
d90fd774 SRRH |
3089 | } |
3090 | ||
28575c61 SRV |
3091 | #ifdef CONFIG_RING_BUFFER_RECORD_RECURSION |
3092 | # define do_ring_buffer_record_recursion() \ | |
3093 | do_ftrace_record_recursion(_THIS_IP_, _RET_IP_) | |
3094 | #else | |
3095 | # define do_ring_buffer_record_recursion() do { } while (0) | |
3096 | #endif | |
3097 | ||
d90fd774 SRRH |
3098 | /* |
3099 | * The lock and unlock are done within a preempt disable section. | |
3100 | * The current_context per_cpu variable can only be modified | |
3101 | * by the current task between lock and unlock. But it can | |
a0e3a18f SRV |
3102 | * be modified more than once via an interrupt. To pass this |
3103 | * information from the lock to the unlock without having to | |
3104 | * access the 'in_interrupt()' functions again (which do show | |
3105 | * a bit of overhead in something as critical as function tracing, | |
3106 | * we use a bitmask trick. | |
d90fd774 | 3107 | * |
b02414c8 SRV |
3108 | * bit 1 = NMI context |
3109 | * bit 2 = IRQ context | |
3110 | * bit 3 = SoftIRQ context | |
3111 | * bit 4 = normal context. | |
d90fd774 | 3112 | * |
a0e3a18f SRV |
3113 | * This works because this is the order of contexts that can |
3114 | * preempt other contexts. A SoftIRQ never preempts an IRQ | |
3115 | * context. | |
3116 | * | |
3117 | * When the context is determined, the corresponding bit is | |
3118 | * checked and set (if it was set, then a recursion of that context | |
3119 | * happened). | |
3120 | * | |
3121 | * On unlock, we need to clear this bit. To do so, just subtract | |
3122 | * 1 from the current_context and AND it to itself. | |
3123 | * | |
3124 | * (binary) | |
3125 | * 101 - 1 = 100 | |
3126 | * 101 & 100 = 100 (clearing bit zero) | |
3127 | * | |
3128 | * 1010 - 1 = 1001 | |
3129 | * 1010 & 1001 = 1000 (clearing bit 1) | |
3130 | * | |
3131 | * The least significant bit can be cleared this way, and it | |
3132 | * just so happens that it is the same bit corresponding to | |
3133 | * the current context. | |
b02414c8 SRV |
3134 | * |
3135 | * Now the TRANSITION bit breaks the above slightly. The TRANSITION bit | |
3136 | * is set when a recursion is detected at the current context, and if | |
3137 | * the TRANSITION bit is already set, it will fail the recursion. | |
3138 | * This is needed because there's a lag between the changing of | |
3139 | * interrupt context and updating the preempt count. In this case, | |
3140 | * a false positive will be found. To handle this, one extra recursion | |
3141 | * is allowed, and this is done by the TRANSITION bit. If the TRANSITION | |
3142 | * bit is already set, then it is considered a recursion and the function | |
3143 | * ends. Otherwise, the TRANSITION bit is set, and that bit is returned. | |
3144 | * | |
3145 | * On the trace_recursive_unlock(), the TRANSITION bit will be the first | |
3146 | * to be cleared. Even if it wasn't the context that set it. That is, | |
3147 | * if an interrupt comes in while NORMAL bit is set and the ring buffer | |
3148 | * is called before preempt_count() is updated, since the check will | |
3149 | * be on the NORMAL bit, the TRANSITION bit will then be set. If an | |
3150 | * NMI then comes in, it will set the NMI bit, but when the NMI code | |
f2cc020d | 3151 | * does the trace_recursive_unlock() it will clear the TRANSITION bit |
b02414c8 SRV |
3152 | * and leave the NMI bit set. But this is fine, because the interrupt |
3153 | * code that set the TRANSITION bit will then clear the NMI bit when it | |
3154 | * calls trace_recursive_unlock(). If another NMI comes in, it will | |
3155 | * set the TRANSITION bit and continue. | |
3156 | * | |
3157 | * Note: The TRANSITION bit only handles a single transition between context. | |
d90fd774 SRRH |
3158 | */ |
3159 | ||
bc92b956 | 3160 | static __always_inline bool |
d90fd774 SRRH |
3161 | trace_recursive_lock(struct ring_buffer_per_cpu *cpu_buffer) |
3162 | { | |
a0e3a18f | 3163 | unsigned int val = cpu_buffer->current_context; |
91ebe8bc | 3164 | int bit = interrupt_context_level(); |
9b84fadc SRV |
3165 | |
3166 | bit = RB_CTX_NORMAL - bit; | |
a0e3a18f | 3167 | |
b02414c8 SRV |
3168 | if (unlikely(val & (1 << (bit + cpu_buffer->nest)))) { |
3169 | /* | |
3170 | * It is possible that this was called by transitioning | |
3171 | * between interrupt context, and preempt_count() has not | |
3172 | * been updated yet. In this case, use the TRANSITION bit. | |
3173 | */ | |
3174 | bit = RB_CTX_TRANSITION; | |
28575c61 SRV |
3175 | if (val & (1 << (bit + cpu_buffer->nest))) { |
3176 | do_ring_buffer_record_recursion(); | |
bc92b956 | 3177 | return true; |
28575c61 | 3178 | } |
b02414c8 | 3179 | } |
d90fd774 | 3180 | |
8e012066 | 3181 | val |= (1 << (bit + cpu_buffer->nest)); |
a0e3a18f | 3182 | cpu_buffer->current_context = val; |
d90fd774 | 3183 | |
bc92b956 | 3184 | return false; |
d90fd774 SRRH |
3185 | } |
3186 | ||
3187 | static __always_inline void | |
3188 | trace_recursive_unlock(struct ring_buffer_per_cpu *cpu_buffer) | |
3189 | { | |
8e012066 SRV |
3190 | cpu_buffer->current_context &= |
3191 | cpu_buffer->current_context - (1 << cpu_buffer->nest); | |
3192 | } | |
3193 | ||
b02414c8 SRV |
3194 | /* The recursive locking above uses 5 bits */ |
3195 | #define NESTED_BITS 5 | |
8e012066 SRV |
3196 | |
3197 | /** | |
3198 | * ring_buffer_nest_start - Allow to trace while nested | |
3199 | * @buffer: The ring buffer to modify | |
3200 | * | |
6167c205 | 3201 | * The ring buffer has a safety mechanism to prevent recursion. |
8e012066 SRV |
3202 | * But there may be a case where a trace needs to be done while |
3203 | * tracing something else. In this case, calling this function | |
3204 | * will allow this function to nest within a currently active | |
3205 | * ring_buffer_lock_reserve(). | |
3206 | * | |
3207 | * Call this function before calling another ring_buffer_lock_reserve() and | |
3208 | * call ring_buffer_nest_end() after the nested ring_buffer_unlock_commit(). | |
3209 | */ | |
13292494 | 3210 | void ring_buffer_nest_start(struct trace_buffer *buffer) |
8e012066 SRV |
3211 | { |
3212 | struct ring_buffer_per_cpu *cpu_buffer; | |
3213 | int cpu; | |
3214 | ||
3215 | /* Enabled by ring_buffer_nest_end() */ | |
3216 | preempt_disable_notrace(); | |
3217 | cpu = raw_smp_processor_id(); | |
3218 | cpu_buffer = buffer->buffers[cpu]; | |
6167c205 | 3219 | /* This is the shift value for the above recursive locking */ |
8e012066 SRV |
3220 | cpu_buffer->nest += NESTED_BITS; |
3221 | } | |
3222 | ||
3223 | /** | |
3224 | * ring_buffer_nest_end - Allow to trace while nested | |
3225 | * @buffer: The ring buffer to modify | |
3226 | * | |
3227 | * Must be called after ring_buffer_nest_start() and after the | |
3228 | * ring_buffer_unlock_commit(). | |
3229 | */ | |
13292494 | 3230 | void ring_buffer_nest_end(struct trace_buffer *buffer) |
8e012066 SRV |
3231 | { |
3232 | struct ring_buffer_per_cpu *cpu_buffer; | |
3233 | int cpu; | |
3234 | ||
3235 | /* disabled by ring_buffer_nest_start() */ | |
3236 | cpu = raw_smp_processor_id(); | |
3237 | cpu_buffer = buffer->buffers[cpu]; | |
6167c205 | 3238 | /* This is the shift value for the above recursive locking */ |
8e012066 SRV |
3239 | cpu_buffer->nest -= NESTED_BITS; |
3240 | preempt_enable_notrace(); | |
d90fd774 SRRH |
3241 | } |
3242 | ||
3243 | /** | |
3244 | * ring_buffer_unlock_commit - commit a reserved | |
3245 | * @buffer: The buffer to commit to | |
d90fd774 SRRH |
3246 | * |
3247 | * This commits the data to the ring buffer, and releases any locks held. | |
3248 | * | |
3249 | * Must be paired with ring_buffer_lock_reserve. | |
3250 | */ | |
04aabc32 | 3251 | int ring_buffer_unlock_commit(struct trace_buffer *buffer) |
d90fd774 SRRH |
3252 | { |
3253 | struct ring_buffer_per_cpu *cpu_buffer; | |
3254 | int cpu = raw_smp_processor_id(); | |
3255 | ||
3256 | cpu_buffer = buffer->buffers[cpu]; | |
3257 | ||
04aabc32 | 3258 | rb_commit(cpu_buffer); |
d90fd774 SRRH |
3259 | |
3260 | rb_wakeups(buffer, cpu_buffer); | |
3261 | ||
3262 | trace_recursive_unlock(cpu_buffer); | |
3263 | ||
3264 | preempt_enable_notrace(); | |
3265 | ||
3266 | return 0; | |
3267 | } | |
3268 | EXPORT_SYMBOL_GPL(ring_buffer_unlock_commit); | |
3269 | ||
5b7be9c7 SRV |
3270 | /* Special value to validate all deltas on a page. */ |
3271 | #define CHECK_FULL_PAGE 1L | |
3272 | ||
3273 | #ifdef CONFIG_RING_BUFFER_VALIDATE_TIME_DELTAS | |
d40dbb61 SRG |
3274 | |
3275 | static const char *show_irq_str(int bits) | |
3276 | { | |
3277 | const char *type[] = { | |
3278 | ".", // 0 | |
3279 | "s", // 1 | |
3280 | "h", // 2 | |
3281 | "Hs", // 3 | |
3282 | "n", // 4 | |
3283 | "Ns", // 5 | |
3284 | "Nh", // 6 | |
3285 | "NHs", // 7 | |
3286 | }; | |
3287 | ||
3288 | return type[bits]; | |
3289 | } | |
3290 | ||
3291 | /* Assume this is an trace event */ | |
3292 | static const char *show_flags(struct ring_buffer_event *event) | |
3293 | { | |
3294 | struct trace_entry *entry; | |
3295 | int bits = 0; | |
3296 | ||
3297 | if (rb_event_data_length(event) - RB_EVNT_HDR_SIZE < sizeof(*entry)) | |
3298 | return "X"; | |
3299 | ||
3300 | entry = ring_buffer_event_data(event); | |
3301 | ||
3302 | if (entry->flags & TRACE_FLAG_SOFTIRQ) | |
3303 | bits |= 1; | |
3304 | ||
3305 | if (entry->flags & TRACE_FLAG_HARDIRQ) | |
3306 | bits |= 2; | |
3307 | ||
3308 | if (entry->flags & TRACE_FLAG_NMI) | |
3309 | bits |= 4; | |
3310 | ||
3311 | return show_irq_str(bits); | |
3312 | } | |
3313 | ||
3314 | static const char *show_irq(struct ring_buffer_event *event) | |
3315 | { | |
3316 | struct trace_entry *entry; | |
3317 | ||
3318 | if (rb_event_data_length(event) - RB_EVNT_HDR_SIZE < sizeof(*entry)) | |
3319 | return ""; | |
3320 | ||
3321 | entry = ring_buffer_event_data(event); | |
3322 | if (entry->flags & TRACE_FLAG_IRQS_OFF) | |
3323 | return "d"; | |
3324 | return ""; | |
3325 | } | |
3326 | ||
3327 | static const char *show_interrupt_level(void) | |
3328 | { | |
3329 | unsigned long pc = preempt_count(); | |
3330 | unsigned char level = 0; | |
3331 | ||
3332 | if (pc & SOFTIRQ_OFFSET) | |
3333 | level |= 1; | |
3334 | ||
3335 | if (pc & HARDIRQ_MASK) | |
3336 | level |= 2; | |
3337 | ||
3338 | if (pc & NMI_MASK) | |
3339 | level |= 4; | |
3340 | ||
3341 | return show_irq_str(level); | |
3342 | } | |
3343 | ||
5b7be9c7 SRV |
3344 | static void dump_buffer_page(struct buffer_data_page *bpage, |
3345 | struct rb_event_info *info, | |
3346 | unsigned long tail) | |
3347 | { | |
3348 | struct ring_buffer_event *event; | |
3349 | u64 ts, delta; | |
3350 | int e; | |
3351 | ||
3352 | ts = bpage->time_stamp; | |
3353 | pr_warn(" [%lld] PAGE TIME STAMP\n", ts); | |
3354 | ||
3355 | for (e = 0; e < tail; e += rb_event_length(event)) { | |
3356 | ||
3357 | event = (struct ring_buffer_event *)(bpage->data + e); | |
3358 | ||
3359 | switch (event->type_len) { | |
3360 | ||
3361 | case RINGBUF_TYPE_TIME_EXTEND: | |
e20044f7 | 3362 | delta = rb_event_time_stamp(event); |
5b7be9c7 | 3363 | ts += delta; |
0b9036ef SRG |
3364 | pr_warn(" 0x%x: [%lld] delta:%lld TIME EXTEND\n", |
3365 | e, ts, delta); | |
5b7be9c7 SRV |
3366 | break; |
3367 | ||
3368 | case RINGBUF_TYPE_TIME_STAMP: | |
e20044f7 | 3369 | delta = rb_event_time_stamp(event); |
6695da58 | 3370 | ts = rb_fix_abs_ts(delta, ts); |
0b9036ef SRG |
3371 | pr_warn(" 0x%x: [%lld] absolute:%lld TIME STAMP\n", |
3372 | e, ts, delta); | |
5b7be9c7 SRV |
3373 | break; |
3374 | ||
3375 | case RINGBUF_TYPE_PADDING: | |
3376 | ts += event->time_delta; | |
0b9036ef SRG |
3377 | pr_warn(" 0x%x: [%lld] delta:%d PADDING\n", |
3378 | e, ts, event->time_delta); | |
5b7be9c7 SRV |
3379 | break; |
3380 | ||
3381 | case RINGBUF_TYPE_DATA: | |
3382 | ts += event->time_delta; | |
d40dbb61 SRG |
3383 | pr_warn(" 0x%x: [%lld] delta:%d %s%s\n", |
3384 | e, ts, event->time_delta, | |
3385 | show_flags(event), show_irq(event)); | |
5b7be9c7 SRV |
3386 | break; |
3387 | ||
3388 | default: | |
3389 | break; | |
3390 | } | |
3391 | } | |
0b9036ef | 3392 | pr_warn("expected end:0x%lx last event actually ended at:0x%x\n", tail, e); |
5b7be9c7 SRV |
3393 | } |
3394 | ||
3395 | static DEFINE_PER_CPU(atomic_t, checking); | |
3396 | static atomic_t ts_dump; | |
3397 | ||
f50345b4 SRG |
3398 | #define buffer_warn_return(fmt, ...) \ |
3399 | do { \ | |
3400 | /* If another report is happening, ignore this one */ \ | |
3401 | if (atomic_inc_return(&ts_dump) != 1) { \ | |
3402 | atomic_dec(&ts_dump); \ | |
3403 | goto out; \ | |
3404 | } \ | |
3405 | atomic_inc(&cpu_buffer->record_disabled); \ | |
3406 | pr_warn(fmt, ##__VA_ARGS__); \ | |
3407 | dump_buffer_page(bpage, info, tail); \ | |
3408 | atomic_dec(&ts_dump); \ | |
3409 | /* There's some cases in boot up that this can happen */ \ | |
3410 | if (WARN_ON_ONCE(system_state != SYSTEM_BOOTING)) \ | |
3411 | /* Do not re-enable checking */ \ | |
3412 | return; \ | |
3413 | } while (0) | |
3414 | ||
5b7be9c7 SRV |
3415 | /* |
3416 | * Check if the current event time stamp matches the deltas on | |
3417 | * the buffer page. | |
3418 | */ | |
3419 | static void check_buffer(struct ring_buffer_per_cpu *cpu_buffer, | |
3420 | struct rb_event_info *info, | |
3421 | unsigned long tail) | |
3422 | { | |
3423 | struct ring_buffer_event *event; | |
3424 | struct buffer_data_page *bpage; | |
3425 | u64 ts, delta; | |
3426 | bool full = false; | |
3427 | int e; | |
3428 | ||
3429 | bpage = info->tail_page->page; | |
3430 | ||
3431 | if (tail == CHECK_FULL_PAGE) { | |
3432 | full = true; | |
3433 | tail = local_read(&bpage->commit); | |
3434 | } else if (info->add_timestamp & | |
3435 | (RB_ADD_STAMP_FORCE | RB_ADD_STAMP_ABSOLUTE)) { | |
3436 | /* Ignore events with absolute time stamps */ | |
3437 | return; | |
3438 | } | |
3439 | ||
3440 | /* | |
3441 | * Do not check the first event (skip possible extends too). | |
3442 | * Also do not check if previous events have not been committed. | |
3443 | */ | |
3444 | if (tail <= 8 || tail > local_read(&bpage->commit)) | |
3445 | return; | |
3446 | ||
3447 | /* | |
083e9f65 | 3448 | * If this interrupted another event, |
5b7be9c7 SRV |
3449 | */ |
3450 | if (atomic_inc_return(this_cpu_ptr(&checking)) != 1) | |
3451 | goto out; | |
3452 | ||
3453 | ts = bpage->time_stamp; | |
3454 | ||
3455 | for (e = 0; e < tail; e += rb_event_length(event)) { | |
3456 | ||
3457 | event = (struct ring_buffer_event *)(bpage->data + e); | |
3458 | ||
3459 | switch (event->type_len) { | |
3460 | ||
3461 | case RINGBUF_TYPE_TIME_EXTEND: | |
e20044f7 | 3462 | delta = rb_event_time_stamp(event); |
5b7be9c7 SRV |
3463 | ts += delta; |
3464 | break; | |
3465 | ||
3466 | case RINGBUF_TYPE_TIME_STAMP: | |
e20044f7 | 3467 | delta = rb_event_time_stamp(event); |
f50345b4 SRG |
3468 | delta = rb_fix_abs_ts(delta, ts); |
3469 | if (delta < ts) { | |
3470 | buffer_warn_return("[CPU: %d]ABSOLUTE TIME WENT BACKWARDS: last ts: %lld absolute ts: %lld\n", | |
3471 | cpu_buffer->cpu, ts, delta); | |
3472 | } | |
3473 | ts = delta; | |
5b7be9c7 SRV |
3474 | break; |
3475 | ||
3476 | case RINGBUF_TYPE_PADDING: | |
3477 | if (event->time_delta == 1) | |
3478 | break; | |
957cdcd9 | 3479 | fallthrough; |
5b7be9c7 SRV |
3480 | case RINGBUF_TYPE_DATA: |
3481 | ts += event->time_delta; | |
3482 | break; | |
3483 | ||
3484 | default: | |
3485 | RB_WARN_ON(cpu_buffer, 1); | |
3486 | } | |
3487 | } | |
3488 | if ((full && ts > info->ts) || | |
3489 | (!full && ts + info->delta != info->ts)) { | |
f50345b4 SRG |
3490 | buffer_warn_return("[CPU: %d]TIME DOES NOT MATCH expected:%lld actual:%lld delta:%lld before:%lld after:%lld%s context:%s\n", |
3491 | cpu_buffer->cpu, | |
3492 | ts + info->delta, info->ts, info->delta, | |
3493 | info->before, info->after, | |
3494 | full ? " (full)" : "", show_interrupt_level()); | |
5b7be9c7 SRV |
3495 | } |
3496 | out: | |
3497 | atomic_dec(this_cpu_ptr(&checking)); | |
3498 | } | |
3499 | #else | |
3500 | static inline void check_buffer(struct ring_buffer_per_cpu *cpu_buffer, | |
3501 | struct rb_event_info *info, | |
3502 | unsigned long tail) | |
3503 | { | |
3504 | } | |
3505 | #endif /* CONFIG_RING_BUFFER_VALIDATE_TIME_DELTAS */ | |
3506 | ||
6634ff26 SR |
3507 | static struct ring_buffer_event * |
3508 | __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, | |
fcc742ea | 3509 | struct rb_event_info *info) |
6634ff26 | 3510 | { |
6634ff26 | 3511 | struct ring_buffer_event *event; |
fcc742ea | 3512 | struct buffer_page *tail_page; |
a389d86f | 3513 | unsigned long tail, write, w; |
69d1b839 | 3514 | |
8573636e SRRH |
3515 | /* Don't let the compiler play games with cpu_buffer->tail_page */ |
3516 | tail_page = info->tail_page = READ_ONCE(cpu_buffer->tail_page); | |
a389d86f SRV |
3517 | |
3518 | /*A*/ w = local_read(&tail_page->write) & RB_WRITE_MASK; | |
3519 | barrier(); | |
c84897c0 SRG |
3520 | rb_time_read(&cpu_buffer->before_stamp, &info->before); |
3521 | rb_time_read(&cpu_buffer->write_stamp, &info->after); | |
a389d86f SRV |
3522 | barrier(); |
3523 | info->ts = rb_time_stamp(cpu_buffer->buffer); | |
3524 | ||
58fbc3c6 | 3525 | if ((info->add_timestamp & RB_ADD_STAMP_ABSOLUTE)) { |
a389d86f | 3526 | info->delta = info->ts; |
a389d86f | 3527 | } else { |
58fbc3c6 SRV |
3528 | /* |
3529 | * If interrupting an event time update, we may need an | |
3530 | * absolute timestamp. | |
3531 | * Don't bother if this is the start of a new page (w == 0). | |
3532 | */ | |
b3ae7b67 SRG |
3533 | if (!w) { |
3534 | /* Use the sub-buffer timestamp */ | |
3535 | info->delta = 0; | |
c84897c0 | 3536 | } else if (unlikely(info->before != info->after)) { |
58fbc3c6 SRV |
3537 | info->add_timestamp |= RB_ADD_STAMP_FORCE | RB_ADD_STAMP_EXTEND; |
3538 | info->length += RB_LEN_TIME_EXTEND; | |
3539 | } else { | |
3540 | info->delta = info->ts - info->after; | |
3541 | if (unlikely(test_time_stamp(info->delta))) { | |
3542 | info->add_timestamp |= RB_ADD_STAMP_EXTEND; | |
3543 | info->length += RB_LEN_TIME_EXTEND; | |
3544 | } | |
10464b4a | 3545 | } |
7c4b4a51 | 3546 | } |
b7dc42fd | 3547 | |
10464b4a | 3548 | /*B*/ rb_time_set(&cpu_buffer->before_stamp, info->ts); |
a389d86f SRV |
3549 | |
3550 | /*C*/ write = local_add_return(info->length, &tail_page->write); | |
77ae365e SR |
3551 | |
3552 | /* set write to only the index of the write */ | |
3553 | write &= RB_WRITE_MASK; | |
a389d86f | 3554 | |
fcc742ea | 3555 | tail = write - info->length; |
6634ff26 | 3556 | |
a389d86f | 3557 | /* See if we shot pass the end of this buffer page */ |
139f8400 | 3558 | if (unlikely(write > cpu_buffer->buffer->subbuf_size)) { |
9e45e39d | 3559 | check_buffer(cpu_buffer, info, CHECK_FULL_PAGE); |
a389d86f SRV |
3560 | return rb_move_tail(cpu_buffer, tail, info); |
3561 | } | |
3562 | ||
3563 | if (likely(tail == w)) { | |
a389d86f | 3564 | /* Nothing interrupted us between A and C */ |
10464b4a | 3565 | /*D*/ rb_time_set(&cpu_buffer->write_stamp, info->ts); |
dd939425 SRG |
3566 | /* |
3567 | * If something came in between C and D, the write stamp | |
3568 | * may now not be in sync. But that's fine as the before_stamp | |
3569 | * will be different and then next event will just be forced | |
3570 | * to use an absolute timestamp. | |
3571 | */ | |
7c4b4a51 SRV |
3572 | if (likely(!(info->add_timestamp & |
3573 | (RB_ADD_STAMP_FORCE | RB_ADD_STAMP_ABSOLUTE)))) | |
a389d86f | 3574 | /* This did not interrupt any time update */ |
58fbc3c6 | 3575 | info->delta = info->ts - info->after; |
a389d86f | 3576 | else |
82db909e | 3577 | /* Just use full timestamp for interrupting event */ |
a389d86f | 3578 | info->delta = info->ts; |
5b7be9c7 | 3579 | check_buffer(cpu_buffer, info, tail); |
a389d86f SRV |
3580 | } else { |
3581 | u64 ts; | |
3582 | /* SLOW PATH - Interrupted between A and C */ | |
b803d7c6 SRG |
3583 | |
3584 | /* Save the old before_stamp */ | |
c84897c0 | 3585 | rb_time_read(&cpu_buffer->before_stamp, &info->before); |
b803d7c6 SRG |
3586 | |
3587 | /* | |
3588 | * Read a new timestamp and update the before_stamp to make | |
3589 | * the next event after this one force using an absolute | |
3590 | * timestamp. This is in case an interrupt were to come in | |
3591 | * between E and F. | |
3592 | */ | |
a389d86f | 3593 | ts = rb_time_stamp(cpu_buffer->buffer); |
b803d7c6 SRG |
3594 | rb_time_set(&cpu_buffer->before_stamp, ts); |
3595 | ||
3596 | barrier(); | |
c84897c0 | 3597 | /*E*/ rb_time_read(&cpu_buffer->write_stamp, &info->after); |
a389d86f | 3598 | barrier(); |
b803d7c6 SRG |
3599 | /*F*/ if (write == (local_read(&tail_page->write) & RB_WRITE_MASK) && |
3600 | info->after == info->before && info->after < ts) { | |
3601 | /* | |
3602 | * Nothing came after this event between C and F, it is | |
3603 | * safe to use info->after for the delta as it | |
3604 | * matched info->before and is still valid. | |
3605 | */ | |
58fbc3c6 | 3606 | info->delta = ts - info->after; |
a389d86f SRV |
3607 | } else { |
3608 | /* | |
b803d7c6 | 3609 | * Interrupted between C and F: |
a389d86f SRV |
3610 | * Lost the previous events time stamp. Just set the |
3611 | * delta to zero, and this will be the same time as | |
3612 | * the event this event interrupted. And the events that | |
3613 | * came after this will still be correct (as they would | |
3614 | * have built their delta on the previous event. | |
3615 | */ | |
3616 | info->delta = 0; | |
3617 | } | |
8672e494 | 3618 | info->ts = ts; |
7c4b4a51 | 3619 | info->add_timestamp &= ~RB_ADD_STAMP_FORCE; |
a389d86f SRV |
3620 | } |
3621 | ||
6634ff26 | 3622 | /* |
a4543a2f | 3623 | * If this is the first commit on the page, then it has the same |
b7dc42fd | 3624 | * timestamp as the page itself. |
6634ff26 | 3625 | */ |
7c4b4a51 SRV |
3626 | if (unlikely(!tail && !(info->add_timestamp & |
3627 | (RB_ADD_STAMP_FORCE | RB_ADD_STAMP_ABSOLUTE)))) | |
a4543a2f SRRH |
3628 | info->delta = 0; |
3629 | ||
b7dc42fd SRRH |
3630 | /* We reserved something on the buffer */ |
3631 | ||
3632 | event = __rb_page_index(tail_page, tail); | |
a4543a2f SRRH |
3633 | rb_update_event(cpu_buffer, event, info); |
3634 | ||
3635 | local_inc(&tail_page->entries); | |
6634ff26 | 3636 | |
b7dc42fd SRRH |
3637 | /* |
3638 | * If this is the first commit on the page, then update | |
3639 | * its timestamp. | |
3640 | */ | |
75b21c6d | 3641 | if (unlikely(!tail)) |
b7dc42fd SRRH |
3642 | tail_page->page->time_stamp = info->ts; |
3643 | ||
c64e148a | 3644 | /* account for these added bytes */ |
fcc742ea | 3645 | local_add(info->length, &cpu_buffer->entries_bytes); |
c64e148a | 3646 | |
6634ff26 SR |
3647 | return event; |
3648 | } | |
3649 | ||
fa7ffb39 | 3650 | static __always_inline struct ring_buffer_event * |
13292494 | 3651 | rb_reserve_next_event(struct trace_buffer *buffer, |
62f0b3eb | 3652 | struct ring_buffer_per_cpu *cpu_buffer, |
1cd8d735 | 3653 | unsigned long length) |
7a8e76a3 SR |
3654 | { |
3655 | struct ring_buffer_event *event; | |
fcc742ea | 3656 | struct rb_event_info info; |
818e3dd3 | 3657 | int nr_loops = 0; |
58fbc3c6 | 3658 | int add_ts_default; |
7a8e76a3 | 3659 | |
71229230 SRG |
3660 | /* ring buffer does cmpxchg, make sure it is safe in NMI context */ |
3661 | if (!IS_ENABLED(CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG) && | |
3662 | (unlikely(in_nmi()))) { | |
3663 | return NULL; | |
3664 | } | |
3665 | ||
fa743953 | 3666 | rb_start_commit(cpu_buffer); |
a389d86f | 3667 | /* The commit page can not change after this */ |
fa743953 | 3668 | |
85bac32c | 3669 | #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP |
62f0b3eb SR |
3670 | /* |
3671 | * Due to the ability to swap a cpu buffer from a buffer | |
3672 | * it is possible it was swapped before we committed. | |
3673 | * (committing stops a swap). We check for it here and | |
3674 | * if it happened, we have to fail the write. | |
3675 | */ | |
3676 | barrier(); | |
6aa7de05 | 3677 | if (unlikely(READ_ONCE(cpu_buffer->buffer) != buffer)) { |
62f0b3eb SR |
3678 | local_dec(&cpu_buffer->committing); |
3679 | local_dec(&cpu_buffer->commits); | |
3680 | return NULL; | |
3681 | } | |
85bac32c | 3682 | #endif |
b7dc42fd | 3683 | |
fcc742ea | 3684 | info.length = rb_calculate_event_length(length); |
58fbc3c6 SRV |
3685 | |
3686 | if (ring_buffer_time_stamp_abs(cpu_buffer->buffer)) { | |
3687 | add_ts_default = RB_ADD_STAMP_ABSOLUTE; | |
3688 | info.length += RB_LEN_TIME_EXTEND; | |
139f8400 | 3689 | if (info.length > cpu_buffer->buffer->max_data_size) |
b3ae7b67 | 3690 | goto out_fail; |
58fbc3c6 SRV |
3691 | } else { |
3692 | add_ts_default = RB_ADD_STAMP_NONE; | |
3693 | } | |
3694 | ||
a4543a2f | 3695 | again: |
58fbc3c6 | 3696 | info.add_timestamp = add_ts_default; |
b7dc42fd SRRH |
3697 | info.delta = 0; |
3698 | ||
818e3dd3 SR |
3699 | /* |
3700 | * We allow for interrupts to reenter here and do a trace. | |
3701 | * If one does, it will cause this original code to loop | |
3702 | * back here. Even with heavy interrupts happening, this | |
3703 | * should only happen a few times in a row. If this happens | |
3704 | * 1000 times in a row, there must be either an interrupt | |
3705 | * storm or we have something buggy. | |
3706 | * Bail! | |
3707 | */ | |
3e89c7bb | 3708 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000)) |
fa743953 | 3709 | goto out_fail; |
818e3dd3 | 3710 | |
fcc742ea SRRH |
3711 | event = __rb_reserve_next(cpu_buffer, &info); |
3712 | ||
bd1b7cd3 | 3713 | if (unlikely(PTR_ERR(event) == -EAGAIN)) { |
58fbc3c6 | 3714 | if (info.add_timestamp & (RB_ADD_STAMP_FORCE | RB_ADD_STAMP_EXTEND)) |
bd1b7cd3 | 3715 | info.length -= RB_LEN_TIME_EXTEND; |
bf41a158 | 3716 | goto again; |
bd1b7cd3 | 3717 | } |
bf41a158 | 3718 | |
a389d86f SRV |
3719 | if (likely(event)) |
3720 | return event; | |
fa743953 SR |
3721 | out_fail: |
3722 | rb_end_commit(cpu_buffer); | |
3723 | return NULL; | |
7a8e76a3 SR |
3724 | } |
3725 | ||
3726 | /** | |
3727 | * ring_buffer_lock_reserve - reserve a part of the buffer | |
3728 | * @buffer: the ring buffer to reserve from | |
3729 | * @length: the length of the data to reserve (excluding event header) | |
7a8e76a3 | 3730 | * |
6167c205 | 3731 | * Returns a reserved event on the ring buffer to copy directly to. |
7a8e76a3 SR |
3732 | * The user of this interface will need to get the body to write into |
3733 | * and can use the ring_buffer_event_data() interface. | |
3734 | * | |
3735 | * The length is the length of the data needed, not the event length | |
3736 | * which also includes the event header. | |
3737 | * | |
3738 | * Must be paired with ring_buffer_unlock_commit, unless NULL is returned. | |
3739 | * If NULL is returned, then nothing has been allocated or locked. | |
3740 | */ | |
3741 | struct ring_buffer_event * | |
13292494 | 3742 | ring_buffer_lock_reserve(struct trace_buffer *buffer, unsigned long length) |
7a8e76a3 SR |
3743 | { |
3744 | struct ring_buffer_per_cpu *cpu_buffer; | |
3745 | struct ring_buffer_event *event; | |
5168ae50 | 3746 | int cpu; |
7a8e76a3 | 3747 | |
bf41a158 | 3748 | /* If we are tracing schedule, we don't want to recurse */ |
5168ae50 | 3749 | preempt_disable_notrace(); |
bf41a158 | 3750 | |
3205f806 | 3751 | if (unlikely(atomic_read(&buffer->record_disabled))) |
58a09ec6 | 3752 | goto out; |
261842b7 | 3753 | |
7a8e76a3 SR |
3754 | cpu = raw_smp_processor_id(); |
3755 | ||
3205f806 | 3756 | if (unlikely(!cpumask_test_cpu(cpu, buffer->cpumask))) |
d769041f | 3757 | goto out; |
7a8e76a3 SR |
3758 | |
3759 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 | 3760 | |
3205f806 | 3761 | if (unlikely(atomic_read(&cpu_buffer->record_disabled))) |
d769041f | 3762 | goto out; |
7a8e76a3 | 3763 | |
139f8400 | 3764 | if (unlikely(length > buffer->max_data_size)) |
bf41a158 | 3765 | goto out; |
7a8e76a3 | 3766 | |
58a09ec6 SRRH |
3767 | if (unlikely(trace_recursive_lock(cpu_buffer))) |
3768 | goto out; | |
3769 | ||
62f0b3eb | 3770 | event = rb_reserve_next_event(buffer, cpu_buffer, length); |
7a8e76a3 | 3771 | if (!event) |
58a09ec6 | 3772 | goto out_unlock; |
7a8e76a3 SR |
3773 | |
3774 | return event; | |
3775 | ||
58a09ec6 SRRH |
3776 | out_unlock: |
3777 | trace_recursive_unlock(cpu_buffer); | |
d769041f | 3778 | out: |
5168ae50 | 3779 | preempt_enable_notrace(); |
7a8e76a3 SR |
3780 | return NULL; |
3781 | } | |
c4f50183 | 3782 | EXPORT_SYMBOL_GPL(ring_buffer_lock_reserve); |
7a8e76a3 | 3783 | |
a1863c21 SR |
3784 | /* |
3785 | * Decrement the entries to the page that an event is on. | |
3786 | * The event does not even need to exist, only the pointer | |
3787 | * to the page it is on. This may only be called before the commit | |
3788 | * takes place. | |
3789 | */ | |
3790 | static inline void | |
3791 | rb_decrement_entry(struct ring_buffer_per_cpu *cpu_buffer, | |
3792 | struct ring_buffer_event *event) | |
3793 | { | |
3794 | unsigned long addr = (unsigned long)event; | |
3795 | struct buffer_page *bpage = cpu_buffer->commit_page; | |
3796 | struct buffer_page *start; | |
3797 | ||
3cb30911 | 3798 | addr &= ~((PAGE_SIZE << cpu_buffer->buffer->subbuf_order) - 1); |
a1863c21 SR |
3799 | |
3800 | /* Do the likely case first */ | |
3801 | if (likely(bpage->page == (void *)addr)) { | |
3802 | local_dec(&bpage->entries); | |
3803 | return; | |
3804 | } | |
3805 | ||
3806 | /* | |
3807 | * Because the commit page may be on the reader page we | |
3808 | * start with the next page and check the end loop there. | |
3809 | */ | |
6689bed3 | 3810 | rb_inc_page(&bpage); |
a1863c21 SR |
3811 | start = bpage; |
3812 | do { | |
3813 | if (bpage->page == (void *)addr) { | |
3814 | local_dec(&bpage->entries); | |
3815 | return; | |
3816 | } | |
6689bed3 | 3817 | rb_inc_page(&bpage); |
a1863c21 SR |
3818 | } while (bpage != start); |
3819 | ||
3820 | /* commit not part of this buffer?? */ | |
3821 | RB_WARN_ON(cpu_buffer, 1); | |
3822 | } | |
3823 | ||
fa1b47dd | 3824 | /** |
88883490 | 3825 | * ring_buffer_discard_commit - discard an event that has not been committed |
fa1b47dd SR |
3826 | * @buffer: the ring buffer |
3827 | * @event: non committed event to discard | |
3828 | * | |
dc892f73 SR |
3829 | * Sometimes an event that is in the ring buffer needs to be ignored. |
3830 | * This function lets the user discard an event in the ring buffer | |
3831 | * and then that event will not be read later. | |
3832 | * | |
6167c205 | 3833 | * This function only works if it is called before the item has been |
dc892f73 | 3834 | * committed. It will try to free the event from the ring buffer |
fa1b47dd SR |
3835 | * if another event has not been added behind it. |
3836 | * | |
3837 | * If another event has been added behind it, it will set the event | |
3838 | * up as discarded, and perform the commit. | |
3839 | * | |
3840 | * If this function is called, do not call ring_buffer_unlock_commit on | |
3841 | * the event. | |
3842 | */ | |
13292494 | 3843 | void ring_buffer_discard_commit(struct trace_buffer *buffer, |
fa1b47dd SR |
3844 | struct ring_buffer_event *event) |
3845 | { | |
3846 | struct ring_buffer_per_cpu *cpu_buffer; | |
fa1b47dd SR |
3847 | int cpu; |
3848 | ||
3849 | /* The event is discarded regardless */ | |
f3b9aae1 | 3850 | rb_event_discard(event); |
fa1b47dd | 3851 | |
fa743953 SR |
3852 | cpu = smp_processor_id(); |
3853 | cpu_buffer = buffer->buffers[cpu]; | |
3854 | ||
fa1b47dd SR |
3855 | /* |
3856 | * This must only be called if the event has not been | |
3857 | * committed yet. Thus we can assume that preemption | |
3858 | * is still disabled. | |
3859 | */ | |
fa743953 | 3860 | RB_WARN_ON(buffer, !local_read(&cpu_buffer->committing)); |
fa1b47dd | 3861 | |
a1863c21 | 3862 | rb_decrement_entry(cpu_buffer, event); |
0f2541d2 | 3863 | if (rb_try_to_discard(cpu_buffer, event)) |
edd813bf | 3864 | goto out; |
fa1b47dd | 3865 | |
fa1b47dd | 3866 | out: |
fa743953 | 3867 | rb_end_commit(cpu_buffer); |
fa1b47dd | 3868 | |
58a09ec6 | 3869 | trace_recursive_unlock(cpu_buffer); |
f3b9aae1 | 3870 | |
5168ae50 | 3871 | preempt_enable_notrace(); |
fa1b47dd SR |
3872 | |
3873 | } | |
3874 | EXPORT_SYMBOL_GPL(ring_buffer_discard_commit); | |
3875 | ||
7a8e76a3 SR |
3876 | /** |
3877 | * ring_buffer_write - write data to the buffer without reserving | |
3878 | * @buffer: The ring buffer to write to. | |
3879 | * @length: The length of the data being written (excluding the event header) | |
3880 | * @data: The data to write to the buffer. | |
3881 | * | |
3882 | * This is like ring_buffer_lock_reserve and ring_buffer_unlock_commit as | |
3883 | * one function. If you already have the data to write to the buffer, it | |
3884 | * may be easier to simply call this function. | |
3885 | * | |
3886 | * Note, like ring_buffer_lock_reserve, the length is the length of the data | |
3887 | * and not the length of the event which would hold the header. | |
3888 | */ | |
13292494 | 3889 | int ring_buffer_write(struct trace_buffer *buffer, |
01e3e710 DS |
3890 | unsigned long length, |
3891 | void *data) | |
7a8e76a3 SR |
3892 | { |
3893 | struct ring_buffer_per_cpu *cpu_buffer; | |
3894 | struct ring_buffer_event *event; | |
7a8e76a3 SR |
3895 | void *body; |
3896 | int ret = -EBUSY; | |
5168ae50 | 3897 | int cpu; |
7a8e76a3 | 3898 | |
5168ae50 | 3899 | preempt_disable_notrace(); |
bf41a158 | 3900 | |
52fbe9cd LJ |
3901 | if (atomic_read(&buffer->record_disabled)) |
3902 | goto out; | |
3903 | ||
7a8e76a3 SR |
3904 | cpu = raw_smp_processor_id(); |
3905 | ||
9e01c1b7 | 3906 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
d769041f | 3907 | goto out; |
7a8e76a3 SR |
3908 | |
3909 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 SR |
3910 | |
3911 | if (atomic_read(&cpu_buffer->record_disabled)) | |
3912 | goto out; | |
3913 | ||
139f8400 | 3914 | if (length > buffer->max_data_size) |
be957c44 SR |
3915 | goto out; |
3916 | ||
985e871b SRRH |
3917 | if (unlikely(trace_recursive_lock(cpu_buffer))) |
3918 | goto out; | |
3919 | ||
62f0b3eb | 3920 | event = rb_reserve_next_event(buffer, cpu_buffer, length); |
7a8e76a3 | 3921 | if (!event) |
985e871b | 3922 | goto out_unlock; |
7a8e76a3 SR |
3923 | |
3924 | body = rb_event_data(event); | |
3925 | ||
3926 | memcpy(body, data, length); | |
3927 | ||
04aabc32 | 3928 | rb_commit(cpu_buffer); |
7a8e76a3 | 3929 | |
15693458 SRRH |
3930 | rb_wakeups(buffer, cpu_buffer); |
3931 | ||
7a8e76a3 | 3932 | ret = 0; |
985e871b SRRH |
3933 | |
3934 | out_unlock: | |
3935 | trace_recursive_unlock(cpu_buffer); | |
3936 | ||
7a8e76a3 | 3937 | out: |
5168ae50 | 3938 | preempt_enable_notrace(); |
7a8e76a3 SR |
3939 | |
3940 | return ret; | |
3941 | } | |
c4f50183 | 3942 | EXPORT_SYMBOL_GPL(ring_buffer_write); |
7a8e76a3 | 3943 | |
da58834c | 3944 | static bool rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) |
bf41a158 SR |
3945 | { |
3946 | struct buffer_page *reader = cpu_buffer->reader_page; | |
77ae365e | 3947 | struct buffer_page *head = rb_set_head_page(cpu_buffer); |
bf41a158 SR |
3948 | struct buffer_page *commit = cpu_buffer->commit_page; |
3949 | ||
77ae365e SR |
3950 | /* In case of error, head will be NULL */ |
3951 | if (unlikely(!head)) | |
da58834c | 3952 | return true; |
77ae365e | 3953 | |
67f0d6d9 | 3954 | /* Reader should exhaust content in reader page */ |
fe832be0 | 3955 | if (reader->read != rb_page_size(reader)) |
67f0d6d9 HL |
3956 | return false; |
3957 | ||
3958 | /* | |
3959 | * If writers are committing on the reader page, knowing all | |
3960 | * committed content has been read, the ring buffer is empty. | |
3961 | */ | |
3962 | if (commit == reader) | |
3963 | return true; | |
3964 | ||
3965 | /* | |
3966 | * If writers are committing on a page other than reader page | |
3967 | * and head page, there should always be content to read. | |
3968 | */ | |
3969 | if (commit != head) | |
3970 | return false; | |
3971 | ||
3972 | /* | |
3973 | * Writers are committing on the head page, we just need | |
3974 | * to care about there're committed data, and the reader will | |
3975 | * swap reader page with head page when it is to read data. | |
3976 | */ | |
3977 | return rb_page_commit(commit) == 0; | |
bf41a158 SR |
3978 | } |
3979 | ||
7a8e76a3 SR |
3980 | /** |
3981 | * ring_buffer_record_disable - stop all writes into the buffer | |
3982 | * @buffer: The ring buffer to stop writes to. | |
3983 | * | |
3984 | * This prevents all writes to the buffer. Any attempt to write | |
3985 | * to the buffer after this will fail and return NULL. | |
3986 | * | |
74401729 | 3987 | * The caller should call synchronize_rcu() after this. |
7a8e76a3 | 3988 | */ |
13292494 | 3989 | void ring_buffer_record_disable(struct trace_buffer *buffer) |
7a8e76a3 SR |
3990 | { |
3991 | atomic_inc(&buffer->record_disabled); | |
3992 | } | |
c4f50183 | 3993 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable); |
7a8e76a3 SR |
3994 | |
3995 | /** | |
3996 | * ring_buffer_record_enable - enable writes to the buffer | |
3997 | * @buffer: The ring buffer to enable writes | |
3998 | * | |
3999 | * Note, multiple disables will need the same number of enables | |
c41b20e7 | 4000 | * to truly enable the writing (much like preempt_disable). |
7a8e76a3 | 4001 | */ |
13292494 | 4002 | void ring_buffer_record_enable(struct trace_buffer *buffer) |
7a8e76a3 SR |
4003 | { |
4004 | atomic_dec(&buffer->record_disabled); | |
4005 | } | |
c4f50183 | 4006 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable); |
7a8e76a3 | 4007 | |
499e5470 SR |
4008 | /** |
4009 | * ring_buffer_record_off - stop all writes into the buffer | |
4010 | * @buffer: The ring buffer to stop writes to. | |
4011 | * | |
4012 | * This prevents all writes to the buffer. Any attempt to write | |
4013 | * to the buffer after this will fail and return NULL. | |
4014 | * | |
4015 | * This is different than ring_buffer_record_disable() as | |
87abb3b1 | 4016 | * it works like an on/off switch, where as the disable() version |
499e5470 SR |
4017 | * must be paired with a enable(). |
4018 | */ | |
13292494 | 4019 | void ring_buffer_record_off(struct trace_buffer *buffer) |
499e5470 SR |
4020 | { |
4021 | unsigned int rd; | |
4022 | unsigned int new_rd; | |
4023 | ||
8328e36d | 4024 | rd = atomic_read(&buffer->record_disabled); |
499e5470 | 4025 | do { |
499e5470 | 4026 | new_rd = rd | RB_BUFFER_OFF; |
8328e36d | 4027 | } while (!atomic_try_cmpxchg(&buffer->record_disabled, &rd, new_rd)); |
499e5470 SR |
4028 | } |
4029 | EXPORT_SYMBOL_GPL(ring_buffer_record_off); | |
4030 | ||
4031 | /** | |
4032 | * ring_buffer_record_on - restart writes into the buffer | |
4033 | * @buffer: The ring buffer to start writes to. | |
4034 | * | |
4035 | * This enables all writes to the buffer that was disabled by | |
4036 | * ring_buffer_record_off(). | |
4037 | * | |
4038 | * This is different than ring_buffer_record_enable() as | |
87abb3b1 | 4039 | * it works like an on/off switch, where as the enable() version |
499e5470 SR |
4040 | * must be paired with a disable(). |
4041 | */ | |
13292494 | 4042 | void ring_buffer_record_on(struct trace_buffer *buffer) |
499e5470 SR |
4043 | { |
4044 | unsigned int rd; | |
4045 | unsigned int new_rd; | |
4046 | ||
8328e36d | 4047 | rd = atomic_read(&buffer->record_disabled); |
499e5470 | 4048 | do { |
499e5470 | 4049 | new_rd = rd & ~RB_BUFFER_OFF; |
8328e36d | 4050 | } while (!atomic_try_cmpxchg(&buffer->record_disabled, &rd, new_rd)); |
499e5470 SR |
4051 | } |
4052 | EXPORT_SYMBOL_GPL(ring_buffer_record_on); | |
4053 | ||
4054 | /** | |
4055 | * ring_buffer_record_is_on - return true if the ring buffer can write | |
4056 | * @buffer: The ring buffer to see if write is enabled | |
4057 | * | |
4058 | * Returns true if the ring buffer is in a state that it accepts writes. | |
4059 | */ | |
13292494 | 4060 | bool ring_buffer_record_is_on(struct trace_buffer *buffer) |
499e5470 SR |
4061 | { |
4062 | return !atomic_read(&buffer->record_disabled); | |
4063 | } | |
4064 | ||
73c8d894 MH |
4065 | /** |
4066 | * ring_buffer_record_is_set_on - return true if the ring buffer is set writable | |
4067 | * @buffer: The ring buffer to see if write is set enabled | |
4068 | * | |
4069 | * Returns true if the ring buffer is set writable by ring_buffer_record_on(). | |
4070 | * Note that this does NOT mean it is in a writable state. | |
4071 | * | |
4072 | * It may return true when the ring buffer has been disabled by | |
4073 | * ring_buffer_record_disable(), as that is a temporary disabling of | |
4074 | * the ring buffer. | |
4075 | */ | |
13292494 | 4076 | bool ring_buffer_record_is_set_on(struct trace_buffer *buffer) |
73c8d894 MH |
4077 | { |
4078 | return !(atomic_read(&buffer->record_disabled) & RB_BUFFER_OFF); | |
4079 | } | |
4080 | ||
7a8e76a3 SR |
4081 | /** |
4082 | * ring_buffer_record_disable_cpu - stop all writes into the cpu_buffer | |
4083 | * @buffer: The ring buffer to stop writes to. | |
4084 | * @cpu: The CPU buffer to stop | |
4085 | * | |
4086 | * This prevents all writes to the buffer. Any attempt to write | |
4087 | * to the buffer after this will fail and return NULL. | |
4088 | * | |
74401729 | 4089 | * The caller should call synchronize_rcu() after this. |
7a8e76a3 | 4090 | */ |
13292494 | 4091 | void ring_buffer_record_disable_cpu(struct trace_buffer *buffer, int cpu) |
7a8e76a3 SR |
4092 | { |
4093 | struct ring_buffer_per_cpu *cpu_buffer; | |
4094 | ||
9e01c1b7 | 4095 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 4096 | return; |
7a8e76a3 SR |
4097 | |
4098 | cpu_buffer = buffer->buffers[cpu]; | |
4099 | atomic_inc(&cpu_buffer->record_disabled); | |
4100 | } | |
c4f50183 | 4101 | EXPORT_SYMBOL_GPL(ring_buffer_record_disable_cpu); |
7a8e76a3 SR |
4102 | |
4103 | /** | |
4104 | * ring_buffer_record_enable_cpu - enable writes to the buffer | |
4105 | * @buffer: The ring buffer to enable writes | |
4106 | * @cpu: The CPU to enable. | |
4107 | * | |
4108 | * Note, multiple disables will need the same number of enables | |
c41b20e7 | 4109 | * to truly enable the writing (much like preempt_disable). |
7a8e76a3 | 4110 | */ |
13292494 | 4111 | void ring_buffer_record_enable_cpu(struct trace_buffer *buffer, int cpu) |
7a8e76a3 SR |
4112 | { |
4113 | struct ring_buffer_per_cpu *cpu_buffer; | |
4114 | ||
9e01c1b7 | 4115 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 4116 | return; |
7a8e76a3 SR |
4117 | |
4118 | cpu_buffer = buffer->buffers[cpu]; | |
4119 | atomic_dec(&cpu_buffer->record_disabled); | |
4120 | } | |
c4f50183 | 4121 | EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu); |
7a8e76a3 | 4122 | |
f6195aa0 SR |
4123 | /* |
4124 | * The total entries in the ring buffer is the running counter | |
4125 | * of entries entered into the ring buffer, minus the sum of | |
4126 | * the entries read from the ring buffer and the number of | |
4127 | * entries that were overwritten. | |
4128 | */ | |
4129 | static inline unsigned long | |
4130 | rb_num_of_entries(struct ring_buffer_per_cpu *cpu_buffer) | |
4131 | { | |
4132 | return local_read(&cpu_buffer->entries) - | |
4133 | (local_read(&cpu_buffer->overrun) + cpu_buffer->read); | |
4134 | } | |
4135 | ||
c64e148a VN |
4136 | /** |
4137 | * ring_buffer_oldest_event_ts - get the oldest event timestamp from the buffer | |
4138 | * @buffer: The ring buffer | |
4139 | * @cpu: The per CPU buffer to read from. | |
4140 | */ | |
13292494 | 4141 | u64 ring_buffer_oldest_event_ts(struct trace_buffer *buffer, int cpu) |
c64e148a VN |
4142 | { |
4143 | unsigned long flags; | |
4144 | struct ring_buffer_per_cpu *cpu_buffer; | |
4145 | struct buffer_page *bpage; | |
da830e58 | 4146 | u64 ret = 0; |
c64e148a VN |
4147 | |
4148 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
4149 | return 0; | |
4150 | ||
4151 | cpu_buffer = buffer->buffers[cpu]; | |
7115e3fc | 4152 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
c64e148a VN |
4153 | /* |
4154 | * if the tail is on reader_page, oldest time stamp is on the reader | |
4155 | * page | |
4156 | */ | |
4157 | if (cpu_buffer->tail_page == cpu_buffer->reader_page) | |
4158 | bpage = cpu_buffer->reader_page; | |
4159 | else | |
4160 | bpage = rb_set_head_page(cpu_buffer); | |
54f7be5b SR |
4161 | if (bpage) |
4162 | ret = bpage->page->time_stamp; | |
7115e3fc | 4163 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
c64e148a VN |
4164 | |
4165 | return ret; | |
4166 | } | |
4167 | EXPORT_SYMBOL_GPL(ring_buffer_oldest_event_ts); | |
4168 | ||
4169 | /** | |
45d99ea4 | 4170 | * ring_buffer_bytes_cpu - get the number of bytes unconsumed in a cpu buffer |
c64e148a VN |
4171 | * @buffer: The ring buffer |
4172 | * @cpu: The per CPU buffer to read from. | |
4173 | */ | |
13292494 | 4174 | unsigned long ring_buffer_bytes_cpu(struct trace_buffer *buffer, int cpu) |
c64e148a VN |
4175 | { |
4176 | struct ring_buffer_per_cpu *cpu_buffer; | |
4177 | unsigned long ret; | |
4178 | ||
4179 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
4180 | return 0; | |
4181 | ||
4182 | cpu_buffer = buffer->buffers[cpu]; | |
4183 | ret = local_read(&cpu_buffer->entries_bytes) - cpu_buffer->read_bytes; | |
4184 | ||
4185 | return ret; | |
4186 | } | |
4187 | EXPORT_SYMBOL_GPL(ring_buffer_bytes_cpu); | |
4188 | ||
7a8e76a3 SR |
4189 | /** |
4190 | * ring_buffer_entries_cpu - get the number of entries in a cpu buffer | |
4191 | * @buffer: The ring buffer | |
4192 | * @cpu: The per CPU buffer to get the entries from. | |
4193 | */ | |
13292494 | 4194 | unsigned long ring_buffer_entries_cpu(struct trace_buffer *buffer, int cpu) |
7a8e76a3 SR |
4195 | { |
4196 | struct ring_buffer_per_cpu *cpu_buffer; | |
4197 | ||
9e01c1b7 | 4198 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 4199 | return 0; |
7a8e76a3 SR |
4200 | |
4201 | cpu_buffer = buffer->buffers[cpu]; | |
554f786e | 4202 | |
f6195aa0 | 4203 | return rb_num_of_entries(cpu_buffer); |
7a8e76a3 | 4204 | } |
c4f50183 | 4205 | EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu); |
7a8e76a3 SR |
4206 | |
4207 | /** | |
884bfe89 SP |
4208 | * ring_buffer_overrun_cpu - get the number of overruns caused by the ring |
4209 | * buffer wrapping around (only if RB_FL_OVERWRITE is on). | |
7a8e76a3 SR |
4210 | * @buffer: The ring buffer |
4211 | * @cpu: The per CPU buffer to get the number of overruns from | |
4212 | */ | |
13292494 | 4213 | unsigned long ring_buffer_overrun_cpu(struct trace_buffer *buffer, int cpu) |
7a8e76a3 SR |
4214 | { |
4215 | struct ring_buffer_per_cpu *cpu_buffer; | |
8aabee57 | 4216 | unsigned long ret; |
7a8e76a3 | 4217 | |
9e01c1b7 | 4218 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 4219 | return 0; |
7a8e76a3 SR |
4220 | |
4221 | cpu_buffer = buffer->buffers[cpu]; | |
77ae365e | 4222 | ret = local_read(&cpu_buffer->overrun); |
554f786e SR |
4223 | |
4224 | return ret; | |
7a8e76a3 | 4225 | } |
c4f50183 | 4226 | EXPORT_SYMBOL_GPL(ring_buffer_overrun_cpu); |
7a8e76a3 | 4227 | |
f0d2c681 | 4228 | /** |
884bfe89 SP |
4229 | * ring_buffer_commit_overrun_cpu - get the number of overruns caused by |
4230 | * commits failing due to the buffer wrapping around while there are uncommitted | |
4231 | * events, such as during an interrupt storm. | |
f0d2c681 SR |
4232 | * @buffer: The ring buffer |
4233 | * @cpu: The per CPU buffer to get the number of overruns from | |
4234 | */ | |
4235 | unsigned long | |
13292494 | 4236 | ring_buffer_commit_overrun_cpu(struct trace_buffer *buffer, int cpu) |
f0d2c681 SR |
4237 | { |
4238 | struct ring_buffer_per_cpu *cpu_buffer; | |
4239 | unsigned long ret; | |
4240 | ||
4241 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
4242 | return 0; | |
4243 | ||
4244 | cpu_buffer = buffer->buffers[cpu]; | |
77ae365e | 4245 | ret = local_read(&cpu_buffer->commit_overrun); |
f0d2c681 SR |
4246 | |
4247 | return ret; | |
4248 | } | |
4249 | EXPORT_SYMBOL_GPL(ring_buffer_commit_overrun_cpu); | |
4250 | ||
884bfe89 SP |
4251 | /** |
4252 | * ring_buffer_dropped_events_cpu - get the number of dropped events caused by | |
4253 | * the ring buffer filling up (only if RB_FL_OVERWRITE is off). | |
4254 | * @buffer: The ring buffer | |
4255 | * @cpu: The per CPU buffer to get the number of overruns from | |
4256 | */ | |
4257 | unsigned long | |
13292494 | 4258 | ring_buffer_dropped_events_cpu(struct trace_buffer *buffer, int cpu) |
884bfe89 SP |
4259 | { |
4260 | struct ring_buffer_per_cpu *cpu_buffer; | |
4261 | unsigned long ret; | |
4262 | ||
4263 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
4264 | return 0; | |
4265 | ||
4266 | cpu_buffer = buffer->buffers[cpu]; | |
4267 | ret = local_read(&cpu_buffer->dropped_events); | |
4268 | ||
4269 | return ret; | |
4270 | } | |
4271 | EXPORT_SYMBOL_GPL(ring_buffer_dropped_events_cpu); | |
4272 | ||
ad964704 SRRH |
4273 | /** |
4274 | * ring_buffer_read_events_cpu - get the number of events successfully read | |
4275 | * @buffer: The ring buffer | |
4276 | * @cpu: The per CPU buffer to get the number of events read | |
4277 | */ | |
4278 | unsigned long | |
13292494 | 4279 | ring_buffer_read_events_cpu(struct trace_buffer *buffer, int cpu) |
ad964704 SRRH |
4280 | { |
4281 | struct ring_buffer_per_cpu *cpu_buffer; | |
4282 | ||
4283 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
4284 | return 0; | |
4285 | ||
4286 | cpu_buffer = buffer->buffers[cpu]; | |
4287 | return cpu_buffer->read; | |
4288 | } | |
4289 | EXPORT_SYMBOL_GPL(ring_buffer_read_events_cpu); | |
4290 | ||
7a8e76a3 SR |
4291 | /** |
4292 | * ring_buffer_entries - get the number of entries in a buffer | |
4293 | * @buffer: The ring buffer | |
4294 | * | |
4295 | * Returns the total number of entries in the ring buffer | |
4296 | * (all CPU entries) | |
4297 | */ | |
13292494 | 4298 | unsigned long ring_buffer_entries(struct trace_buffer *buffer) |
7a8e76a3 SR |
4299 | { |
4300 | struct ring_buffer_per_cpu *cpu_buffer; | |
4301 | unsigned long entries = 0; | |
4302 | int cpu; | |
4303 | ||
4304 | /* if you care about this being correct, lock the buffer */ | |
4305 | for_each_buffer_cpu(buffer, cpu) { | |
4306 | cpu_buffer = buffer->buffers[cpu]; | |
f6195aa0 | 4307 | entries += rb_num_of_entries(cpu_buffer); |
7a8e76a3 SR |
4308 | } |
4309 | ||
4310 | return entries; | |
4311 | } | |
c4f50183 | 4312 | EXPORT_SYMBOL_GPL(ring_buffer_entries); |
7a8e76a3 SR |
4313 | |
4314 | /** | |
67b394f7 | 4315 | * ring_buffer_overruns - get the number of overruns in buffer |
7a8e76a3 SR |
4316 | * @buffer: The ring buffer |
4317 | * | |
4318 | * Returns the total number of overruns in the ring buffer | |
4319 | * (all CPU entries) | |
4320 | */ | |
13292494 | 4321 | unsigned long ring_buffer_overruns(struct trace_buffer *buffer) |
7a8e76a3 SR |
4322 | { |
4323 | struct ring_buffer_per_cpu *cpu_buffer; | |
4324 | unsigned long overruns = 0; | |
4325 | int cpu; | |
4326 | ||
4327 | /* if you care about this being correct, lock the buffer */ | |
4328 | for_each_buffer_cpu(buffer, cpu) { | |
4329 | cpu_buffer = buffer->buffers[cpu]; | |
77ae365e | 4330 | overruns += local_read(&cpu_buffer->overrun); |
7a8e76a3 SR |
4331 | } |
4332 | ||
4333 | return overruns; | |
4334 | } | |
c4f50183 | 4335 | EXPORT_SYMBOL_GPL(ring_buffer_overruns); |
7a8e76a3 | 4336 | |
642edba5 | 4337 | static void rb_iter_reset(struct ring_buffer_iter *iter) |
7a8e76a3 SR |
4338 | { |
4339 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
4340 | ||
d769041f | 4341 | /* Iterator usage is expected to have record disabled */ |
651e22f2 SRRH |
4342 | iter->head_page = cpu_buffer->reader_page; |
4343 | iter->head = cpu_buffer->reader_page->read; | |
785888c5 | 4344 | iter->next_event = iter->head; |
651e22f2 SRRH |
4345 | |
4346 | iter->cache_reader_page = iter->head_page; | |
24607f11 | 4347 | iter->cache_read = cpu_buffer->read; |
2d093282 | 4348 | iter->cache_pages_removed = cpu_buffer->pages_removed; |
651e22f2 | 4349 | |
28e3fc56 | 4350 | if (iter->head) { |
d769041f | 4351 | iter->read_stamp = cpu_buffer->read_stamp; |
28e3fc56 SRV |
4352 | iter->page_stamp = cpu_buffer->reader_page->page->time_stamp; |
4353 | } else { | |
abc9b56d | 4354 | iter->read_stamp = iter->head_page->page->time_stamp; |
28e3fc56 SRV |
4355 | iter->page_stamp = iter->read_stamp; |
4356 | } | |
642edba5 | 4357 | } |
f83c9d0f | 4358 | |
642edba5 SR |
4359 | /** |
4360 | * ring_buffer_iter_reset - reset an iterator | |
4361 | * @iter: The iterator to reset | |
4362 | * | |
4363 | * Resets the iterator, so that it will start from the beginning | |
4364 | * again. | |
4365 | */ | |
4366 | void ring_buffer_iter_reset(struct ring_buffer_iter *iter) | |
4367 | { | |
554f786e | 4368 | struct ring_buffer_per_cpu *cpu_buffer; |
642edba5 SR |
4369 | unsigned long flags; |
4370 | ||
554f786e SR |
4371 | if (!iter) |
4372 | return; | |
4373 | ||
4374 | cpu_buffer = iter->cpu_buffer; | |
4375 | ||
5389f6fa | 4376 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
642edba5 | 4377 | rb_iter_reset(iter); |
5389f6fa | 4378 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
7a8e76a3 | 4379 | } |
c4f50183 | 4380 | EXPORT_SYMBOL_GPL(ring_buffer_iter_reset); |
7a8e76a3 SR |
4381 | |
4382 | /** | |
4383 | * ring_buffer_iter_empty - check if an iterator has no more to read | |
4384 | * @iter: The iterator to check | |
4385 | */ | |
4386 | int ring_buffer_iter_empty(struct ring_buffer_iter *iter) | |
4387 | { | |
4388 | struct ring_buffer_per_cpu *cpu_buffer; | |
78f7a45d SRV |
4389 | struct buffer_page *reader; |
4390 | struct buffer_page *head_page; | |
4391 | struct buffer_page *commit_page; | |
ead6ecfd | 4392 | struct buffer_page *curr_commit_page; |
78f7a45d | 4393 | unsigned commit; |
ead6ecfd SRV |
4394 | u64 curr_commit_ts; |
4395 | u64 commit_ts; | |
7a8e76a3 SR |
4396 | |
4397 | cpu_buffer = iter->cpu_buffer; | |
78f7a45d SRV |
4398 | reader = cpu_buffer->reader_page; |
4399 | head_page = cpu_buffer->head_page; | |
f1e30cb6 | 4400 | commit_page = READ_ONCE(cpu_buffer->commit_page); |
ead6ecfd SRV |
4401 | commit_ts = commit_page->page->time_stamp; |
4402 | ||
4403 | /* | |
4404 | * When the writer goes across pages, it issues a cmpxchg which | |
4405 | * is a mb(), which will synchronize with the rmb here. | |
4406 | * (see rb_tail_page_update()) | |
4407 | */ | |
4408 | smp_rmb(); | |
78f7a45d | 4409 | commit = rb_page_commit(commit_page); |
ead6ecfd SRV |
4410 | /* We want to make sure that the commit page doesn't change */ |
4411 | smp_rmb(); | |
4412 | ||
4413 | /* Make sure commit page didn't change */ | |
4414 | curr_commit_page = READ_ONCE(cpu_buffer->commit_page); | |
4415 | curr_commit_ts = READ_ONCE(curr_commit_page->page->time_stamp); | |
4416 | ||
4417 | /* If the commit page changed, then there's more data */ | |
4418 | if (curr_commit_page != commit_page || | |
4419 | curr_commit_ts != commit_ts) | |
4420 | return 0; | |
78f7a45d | 4421 | |
ead6ecfd | 4422 | /* Still racy, as it may return a false positive, but that's OK */ |
785888c5 | 4423 | return ((iter->head_page == commit_page && iter->head >= commit) || |
78f7a45d SRV |
4424 | (iter->head_page == reader && commit_page == head_page && |
4425 | head_page->read == commit && | |
fe832be0 | 4426 | iter->head == rb_page_size(cpu_buffer->reader_page))); |
7a8e76a3 | 4427 | } |
c4f50183 | 4428 | EXPORT_SYMBOL_GPL(ring_buffer_iter_empty); |
7a8e76a3 SR |
4429 | |
4430 | static void | |
4431 | rb_update_read_stamp(struct ring_buffer_per_cpu *cpu_buffer, | |
4432 | struct ring_buffer_event *event) | |
4433 | { | |
4434 | u64 delta; | |
4435 | ||
334d4169 | 4436 | switch (event->type_len) { |
7a8e76a3 SR |
4437 | case RINGBUF_TYPE_PADDING: |
4438 | return; | |
4439 | ||
4440 | case RINGBUF_TYPE_TIME_EXTEND: | |
e20044f7 | 4441 | delta = rb_event_time_stamp(event); |
7a8e76a3 SR |
4442 | cpu_buffer->read_stamp += delta; |
4443 | return; | |
4444 | ||
4445 | case RINGBUF_TYPE_TIME_STAMP: | |
e20044f7 | 4446 | delta = rb_event_time_stamp(event); |
6695da58 | 4447 | delta = rb_fix_abs_ts(delta, cpu_buffer->read_stamp); |
dc4e2801 | 4448 | cpu_buffer->read_stamp = delta; |
7a8e76a3 SR |
4449 | return; |
4450 | ||
4451 | case RINGBUF_TYPE_DATA: | |
4452 | cpu_buffer->read_stamp += event->time_delta; | |
4453 | return; | |
4454 | ||
4455 | default: | |
da4d401a | 4456 | RB_WARN_ON(cpu_buffer, 1); |
7a8e76a3 | 4457 | } |
7a8e76a3 SR |
4458 | } |
4459 | ||
4460 | static void | |
4461 | rb_update_iter_read_stamp(struct ring_buffer_iter *iter, | |
4462 | struct ring_buffer_event *event) | |
4463 | { | |
4464 | u64 delta; | |
4465 | ||
334d4169 | 4466 | switch (event->type_len) { |
7a8e76a3 SR |
4467 | case RINGBUF_TYPE_PADDING: |
4468 | return; | |
4469 | ||
4470 | case RINGBUF_TYPE_TIME_EXTEND: | |
e20044f7 | 4471 | delta = rb_event_time_stamp(event); |
7a8e76a3 SR |
4472 | iter->read_stamp += delta; |
4473 | return; | |
4474 | ||
4475 | case RINGBUF_TYPE_TIME_STAMP: | |
e20044f7 | 4476 | delta = rb_event_time_stamp(event); |
6695da58 | 4477 | delta = rb_fix_abs_ts(delta, iter->read_stamp); |
dc4e2801 | 4478 | iter->read_stamp = delta; |
7a8e76a3 SR |
4479 | return; |
4480 | ||
4481 | case RINGBUF_TYPE_DATA: | |
4482 | iter->read_stamp += event->time_delta; | |
4483 | return; | |
4484 | ||
4485 | default: | |
da4d401a | 4486 | RB_WARN_ON(iter->cpu_buffer, 1); |
7a8e76a3 | 4487 | } |
7a8e76a3 SR |
4488 | } |
4489 | ||
d769041f SR |
4490 | static struct buffer_page * |
4491 | rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) | |
7a8e76a3 | 4492 | { |
d769041f | 4493 | struct buffer_page *reader = NULL; |
139f8400 | 4494 | unsigned long bsize = READ_ONCE(cpu_buffer->buffer->subbuf_size); |
66a8cb95 | 4495 | unsigned long overwrite; |
d769041f | 4496 | unsigned long flags; |
818e3dd3 | 4497 | int nr_loops = 0; |
bc92b956 | 4498 | bool ret; |
d769041f | 4499 | |
3e03fb7f | 4500 | local_irq_save(flags); |
0199c4e6 | 4501 | arch_spin_lock(&cpu_buffer->lock); |
d769041f SR |
4502 | |
4503 | again: | |
818e3dd3 SR |
4504 | /* |
4505 | * This should normally only loop twice. But because the | |
4506 | * start of the reader inserts an empty page, it causes | |
4507 | * a case where we will loop three times. There should be no | |
4508 | * reason to loop four times (that I know of). | |
4509 | */ | |
3e89c7bb | 4510 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 3)) { |
818e3dd3 SR |
4511 | reader = NULL; |
4512 | goto out; | |
4513 | } | |
4514 | ||
d769041f SR |
4515 | reader = cpu_buffer->reader_page; |
4516 | ||
4517 | /* If there's more to read, return this page */ | |
bf41a158 | 4518 | if (cpu_buffer->reader_page->read < rb_page_size(reader)) |
d769041f SR |
4519 | goto out; |
4520 | ||
4521 | /* Never should we have an index greater than the size */ | |
3e89c7bb SR |
4522 | if (RB_WARN_ON(cpu_buffer, |
4523 | cpu_buffer->reader_page->read > rb_page_size(reader))) | |
4524 | goto out; | |
d769041f SR |
4525 | |
4526 | /* check if we caught up to the tail */ | |
4527 | reader = NULL; | |
bf41a158 | 4528 | if (cpu_buffer->commit_page == cpu_buffer->reader_page) |
d769041f | 4529 | goto out; |
7a8e76a3 | 4530 | |
a5fb8331 SR |
4531 | /* Don't bother swapping if the ring buffer is empty */ |
4532 | if (rb_num_of_entries(cpu_buffer) == 0) | |
4533 | goto out; | |
4534 | ||
7a8e76a3 | 4535 | /* |
d769041f | 4536 | * Reset the reader page to size zero. |
7a8e76a3 | 4537 | */ |
77ae365e SR |
4538 | local_set(&cpu_buffer->reader_page->write, 0); |
4539 | local_set(&cpu_buffer->reader_page->entries, 0); | |
4540 | local_set(&cpu_buffer->reader_page->page->commit, 0); | |
ff0ff84a | 4541 | cpu_buffer->reader_page->real_end = 0; |
7a8e76a3 | 4542 | |
77ae365e SR |
4543 | spin: |
4544 | /* | |
4545 | * Splice the empty reader page into the list around the head. | |
4546 | */ | |
4547 | reader = rb_set_head_page(cpu_buffer); | |
54f7be5b SR |
4548 | if (!reader) |
4549 | goto out; | |
0e1ff5d7 | 4550 | cpu_buffer->reader_page->list.next = rb_list_head(reader->list.next); |
d769041f | 4551 | cpu_buffer->reader_page->list.prev = reader->list.prev; |
bf41a158 | 4552 | |
3adc54fa SR |
4553 | /* |
4554 | * cpu_buffer->pages just needs to point to the buffer, it | |
4555 | * has no specific buffer page to point to. Lets move it out | |
25985edc | 4556 | * of our way so we don't accidentally swap it. |
3adc54fa SR |
4557 | */ |
4558 | cpu_buffer->pages = reader->list.prev; | |
4559 | ||
77ae365e | 4560 | /* The reader page will be pointing to the new head */ |
6689bed3 | 4561 | rb_set_list_to_head(&cpu_buffer->reader_page->list); |
7a8e76a3 | 4562 | |
66a8cb95 SR |
4563 | /* |
4564 | * We want to make sure we read the overruns after we set up our | |
4565 | * pointers to the next object. The writer side does a | |
4566 | * cmpxchg to cross pages which acts as the mb on the writer | |
4567 | * side. Note, the reader will constantly fail the swap | |
4568 | * while the writer is updating the pointers, so this | |
4569 | * guarantees that the overwrite recorded here is the one we | |
4570 | * want to compare with the last_overrun. | |
4571 | */ | |
4572 | smp_mb(); | |
4573 | overwrite = local_read(&(cpu_buffer->overrun)); | |
4574 | ||
77ae365e SR |
4575 | /* |
4576 | * Here's the tricky part. | |
4577 | * | |
4578 | * We need to move the pointer past the header page. | |
4579 | * But we can only do that if a writer is not currently | |
4580 | * moving it. The page before the header page has the | |
4581 | * flag bit '1' set if it is pointing to the page we want. | |
4582 | * but if the writer is in the process of moving it | |
4583 | * than it will be '2' or already moved '0'. | |
4584 | */ | |
4585 | ||
4586 | ret = rb_head_page_replace(reader, cpu_buffer->reader_page); | |
7a8e76a3 SR |
4587 | |
4588 | /* | |
77ae365e | 4589 | * If we did not convert it, then we must try again. |
7a8e76a3 | 4590 | */ |
77ae365e SR |
4591 | if (!ret) |
4592 | goto spin; | |
7a8e76a3 | 4593 | |
77ae365e | 4594 | /* |
2c2b0a78 | 4595 | * Yay! We succeeded in replacing the page. |
77ae365e SR |
4596 | * |
4597 | * Now make the new head point back to the reader page. | |
4598 | */ | |
5ded3dc6 | 4599 | rb_list_head(reader->list.next)->prev = &cpu_buffer->reader_page->list; |
6689bed3 | 4600 | rb_inc_page(&cpu_buffer->head_page); |
d769041f | 4601 | |
2c2b0a78 SRV |
4602 | local_inc(&cpu_buffer->pages_read); |
4603 | ||
d769041f SR |
4604 | /* Finally update the reader page to the new head */ |
4605 | cpu_buffer->reader_page = reader; | |
b81f472a | 4606 | cpu_buffer->reader_page->read = 0; |
d769041f | 4607 | |
66a8cb95 SR |
4608 | if (overwrite != cpu_buffer->last_overrun) { |
4609 | cpu_buffer->lost_events = overwrite - cpu_buffer->last_overrun; | |
4610 | cpu_buffer->last_overrun = overwrite; | |
4611 | } | |
4612 | ||
d769041f SR |
4613 | goto again; |
4614 | ||
4615 | out: | |
b81f472a SRRH |
4616 | /* Update the read_stamp on the first event */ |
4617 | if (reader && reader->read == 0) | |
4618 | cpu_buffer->read_stamp = reader->page->time_stamp; | |
4619 | ||
0199c4e6 | 4620 | arch_spin_unlock(&cpu_buffer->lock); |
3e03fb7f | 4621 | local_irq_restore(flags); |
d769041f | 4622 | |
a0fcaaed SRG |
4623 | /* |
4624 | * The writer has preempt disable, wait for it. But not forever | |
4625 | * Although, 1 second is pretty much "forever" | |
4626 | */ | |
4627 | #define USECS_WAIT 1000000 | |
4628 | for (nr_loops = 0; nr_loops < USECS_WAIT; nr_loops++) { | |
4629 | /* If the write is past the end of page, a writer is still updating it */ | |
139f8400 | 4630 | if (likely(!reader || rb_page_write(reader) <= bsize)) |
a0fcaaed SRG |
4631 | break; |
4632 | ||
4633 | udelay(1); | |
4634 | ||
4635 | /* Get the latest version of the reader write value */ | |
4636 | smp_rmb(); | |
4637 | } | |
4638 | ||
4639 | /* The writer is not moving forward? Something is wrong */ | |
4640 | if (RB_WARN_ON(cpu_buffer, nr_loops == USECS_WAIT)) | |
4641 | reader = NULL; | |
4642 | ||
4643 | /* | |
4644 | * Make sure we see any padding after the write update | |
6455b616 ZY |
4645 | * (see rb_reset_tail()). |
4646 | * | |
4647 | * In addition, a writer may be writing on the reader page | |
4648 | * if the page has not been fully filled, so the read barrier | |
4649 | * is also needed to make sure we see the content of what is | |
4650 | * committed by the writer (see rb_set_commit_to_write()). | |
a0fcaaed SRG |
4651 | */ |
4652 | smp_rmb(); | |
4653 | ||
4654 | ||
d769041f SR |
4655 | return reader; |
4656 | } | |
4657 | ||
4658 | static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer) | |
4659 | { | |
4660 | struct ring_buffer_event *event; | |
4661 | struct buffer_page *reader; | |
4662 | unsigned length; | |
4663 | ||
4664 | reader = rb_get_reader_page(cpu_buffer); | |
7a8e76a3 | 4665 | |
d769041f | 4666 | /* This function should not be called when buffer is empty */ |
3e89c7bb SR |
4667 | if (RB_WARN_ON(cpu_buffer, !reader)) |
4668 | return; | |
7a8e76a3 | 4669 | |
d769041f SR |
4670 | event = rb_reader_event(cpu_buffer); |
4671 | ||
a1863c21 | 4672 | if (event->type_len <= RINGBUF_TYPE_DATA_TYPE_LEN_MAX) |
e4906eff | 4673 | cpu_buffer->read++; |
d769041f SR |
4674 | |
4675 | rb_update_read_stamp(cpu_buffer, event); | |
4676 | ||
4677 | length = rb_event_length(event); | |
6f807acd | 4678 | cpu_buffer->reader_page->read += length; |
45d99ea4 | 4679 | cpu_buffer->read_bytes += length; |
7a8e76a3 SR |
4680 | } |
4681 | ||
4682 | static void rb_advance_iter(struct ring_buffer_iter *iter) | |
4683 | { | |
7a8e76a3 | 4684 | struct ring_buffer_per_cpu *cpu_buffer; |
7a8e76a3 SR |
4685 | |
4686 | cpu_buffer = iter->cpu_buffer; | |
7a8e76a3 | 4687 | |
785888c5 SRV |
4688 | /* If head == next_event then we need to jump to the next event */ |
4689 | if (iter->head == iter->next_event) { | |
4690 | /* If the event gets overwritten again, there's nothing to do */ | |
4691 | if (rb_iter_head_event(iter) == NULL) | |
4692 | return; | |
4693 | } | |
4694 | ||
4695 | iter->head = iter->next_event; | |
4696 | ||
7a8e76a3 SR |
4697 | /* |
4698 | * Check if we are at the end of the buffer. | |
4699 | */ | |
785888c5 | 4700 | if (iter->next_event >= rb_page_size(iter->head_page)) { |
ea05b57c SR |
4701 | /* discarded commits can make the page empty */ |
4702 | if (iter->head_page == cpu_buffer->commit_page) | |
3e89c7bb | 4703 | return; |
d769041f | 4704 | rb_inc_iter(iter); |
7a8e76a3 SR |
4705 | return; |
4706 | } | |
4707 | ||
785888c5 | 4708 | rb_update_iter_read_stamp(iter, iter->event); |
7a8e76a3 SR |
4709 | } |
4710 | ||
66a8cb95 SR |
4711 | static int rb_lost_events(struct ring_buffer_per_cpu *cpu_buffer) |
4712 | { | |
4713 | return cpu_buffer->lost_events; | |
4714 | } | |
4715 | ||
f83c9d0f | 4716 | static struct ring_buffer_event * |
66a8cb95 SR |
4717 | rb_buffer_peek(struct ring_buffer_per_cpu *cpu_buffer, u64 *ts, |
4718 | unsigned long *lost_events) | |
7a8e76a3 | 4719 | { |
7a8e76a3 | 4720 | struct ring_buffer_event *event; |
d769041f | 4721 | struct buffer_page *reader; |
818e3dd3 | 4722 | int nr_loops = 0; |
7a8e76a3 | 4723 | |
dc4e2801 TZ |
4724 | if (ts) |
4725 | *ts = 0; | |
7a8e76a3 | 4726 | again: |
818e3dd3 | 4727 | /* |
69d1b839 SR |
4728 | * We repeat when a time extend is encountered. |
4729 | * Since the time extend is always attached to a data event, | |
4730 | * we should never loop more than once. | |
4731 | * (We never hit the following condition more than twice). | |
818e3dd3 | 4732 | */ |
69d1b839 | 4733 | if (RB_WARN_ON(cpu_buffer, ++nr_loops > 2)) |
818e3dd3 | 4734 | return NULL; |
818e3dd3 | 4735 | |
d769041f SR |
4736 | reader = rb_get_reader_page(cpu_buffer); |
4737 | if (!reader) | |
7a8e76a3 SR |
4738 | return NULL; |
4739 | ||
d769041f | 4740 | event = rb_reader_event(cpu_buffer); |
7a8e76a3 | 4741 | |
334d4169 | 4742 | switch (event->type_len) { |
7a8e76a3 | 4743 | case RINGBUF_TYPE_PADDING: |
2d622719 TZ |
4744 | if (rb_null_event(event)) |
4745 | RB_WARN_ON(cpu_buffer, 1); | |
4746 | /* | |
4747 | * Because the writer could be discarding every | |
4748 | * event it creates (which would probably be bad) | |
4749 | * if we were to go back to "again" then we may never | |
4750 | * catch up, and will trigger the warn on, or lock | |
4751 | * the box. Return the padding, and we will release | |
4752 | * the current locks, and try again. | |
4753 | */ | |
2d622719 | 4754 | return event; |
7a8e76a3 SR |
4755 | |
4756 | case RINGBUF_TYPE_TIME_EXTEND: | |
4757 | /* Internal data, OK to advance */ | |
d769041f | 4758 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
4759 | goto again; |
4760 | ||
4761 | case RINGBUF_TYPE_TIME_STAMP: | |
dc4e2801 | 4762 | if (ts) { |
e20044f7 | 4763 | *ts = rb_event_time_stamp(event); |
6695da58 | 4764 | *ts = rb_fix_abs_ts(*ts, reader->page->time_stamp); |
dc4e2801 TZ |
4765 | ring_buffer_normalize_time_stamp(cpu_buffer->buffer, |
4766 | cpu_buffer->cpu, ts); | |
4767 | } | |
4768 | /* Internal data, OK to advance */ | |
d769041f | 4769 | rb_advance_reader(cpu_buffer); |
7a8e76a3 SR |
4770 | goto again; |
4771 | ||
4772 | case RINGBUF_TYPE_DATA: | |
dc4e2801 | 4773 | if (ts && !(*ts)) { |
7a8e76a3 | 4774 | *ts = cpu_buffer->read_stamp + event->time_delta; |
d8eeb2d3 | 4775 | ring_buffer_normalize_time_stamp(cpu_buffer->buffer, |
37886f6a | 4776 | cpu_buffer->cpu, ts); |
7a8e76a3 | 4777 | } |
66a8cb95 SR |
4778 | if (lost_events) |
4779 | *lost_events = rb_lost_events(cpu_buffer); | |
7a8e76a3 SR |
4780 | return event; |
4781 | ||
4782 | default: | |
da4d401a | 4783 | RB_WARN_ON(cpu_buffer, 1); |
7a8e76a3 SR |
4784 | } |
4785 | ||
4786 | return NULL; | |
4787 | } | |
c4f50183 | 4788 | EXPORT_SYMBOL_GPL(ring_buffer_peek); |
7a8e76a3 | 4789 | |
f83c9d0f SR |
4790 | static struct ring_buffer_event * |
4791 | rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) | |
7a8e76a3 | 4792 | { |
13292494 | 4793 | struct trace_buffer *buffer; |
7a8e76a3 SR |
4794 | struct ring_buffer_per_cpu *cpu_buffer; |
4795 | struct ring_buffer_event *event; | |
818e3dd3 | 4796 | int nr_loops = 0; |
7a8e76a3 | 4797 | |
dc4e2801 TZ |
4798 | if (ts) |
4799 | *ts = 0; | |
4800 | ||
7a8e76a3 SR |
4801 | cpu_buffer = iter->cpu_buffer; |
4802 | buffer = cpu_buffer->buffer; | |
4803 | ||
492a74f4 | 4804 | /* |
2d093282 ZY |
4805 | * Check if someone performed a consuming read to the buffer |
4806 | * or removed some pages from the buffer. In these cases, | |
4807 | * iterator was invalidated and we need to reset it. | |
492a74f4 SR |
4808 | */ |
4809 | if (unlikely(iter->cache_read != cpu_buffer->read || | |
2d093282 ZY |
4810 | iter->cache_reader_page != cpu_buffer->reader_page || |
4811 | iter->cache_pages_removed != cpu_buffer->pages_removed)) | |
492a74f4 SR |
4812 | rb_iter_reset(iter); |
4813 | ||
7a8e76a3 | 4814 | again: |
3c05d748 SR |
4815 | if (ring_buffer_iter_empty(iter)) |
4816 | return NULL; | |
4817 | ||
818e3dd3 | 4818 | /* |
3d2353de SRV |
4819 | * As the writer can mess with what the iterator is trying |
4820 | * to read, just give up if we fail to get an event after | |
4821 | * three tries. The iterator is not as reliable when reading | |
4822 | * the ring buffer with an active write as the consumer is. | |
4823 | * Do not warn if the three failures is reached. | |
818e3dd3 | 4824 | */ |
3d2353de | 4825 | if (++nr_loops > 3) |
818e3dd3 | 4826 | return NULL; |
818e3dd3 | 4827 | |
7a8e76a3 SR |
4828 | if (rb_per_cpu_empty(cpu_buffer)) |
4829 | return NULL; | |
4830 | ||
10e83fd0 | 4831 | if (iter->head >= rb_page_size(iter->head_page)) { |
3c05d748 SR |
4832 | rb_inc_iter(iter); |
4833 | goto again; | |
4834 | } | |
4835 | ||
7a8e76a3 | 4836 | event = rb_iter_head_event(iter); |
3d2353de | 4837 | if (!event) |
785888c5 | 4838 | goto again; |
7a8e76a3 | 4839 | |
334d4169 | 4840 | switch (event->type_len) { |
7a8e76a3 | 4841 | case RINGBUF_TYPE_PADDING: |
2d622719 TZ |
4842 | if (rb_null_event(event)) { |
4843 | rb_inc_iter(iter); | |
4844 | goto again; | |
4845 | } | |
4846 | rb_advance_iter(iter); | |
4847 | return event; | |
7a8e76a3 SR |
4848 | |
4849 | case RINGBUF_TYPE_TIME_EXTEND: | |
4850 | /* Internal data, OK to advance */ | |
4851 | rb_advance_iter(iter); | |
4852 | goto again; | |
4853 | ||
4854 | case RINGBUF_TYPE_TIME_STAMP: | |
dc4e2801 | 4855 | if (ts) { |
e20044f7 | 4856 | *ts = rb_event_time_stamp(event); |
6695da58 | 4857 | *ts = rb_fix_abs_ts(*ts, iter->head_page->page->time_stamp); |
dc4e2801 TZ |
4858 | ring_buffer_normalize_time_stamp(cpu_buffer->buffer, |
4859 | cpu_buffer->cpu, ts); | |
4860 | } | |
4861 | /* Internal data, OK to advance */ | |
7a8e76a3 SR |
4862 | rb_advance_iter(iter); |
4863 | goto again; | |
4864 | ||
4865 | case RINGBUF_TYPE_DATA: | |
dc4e2801 | 4866 | if (ts && !(*ts)) { |
7a8e76a3 | 4867 | *ts = iter->read_stamp + event->time_delta; |
37886f6a SR |
4868 | ring_buffer_normalize_time_stamp(buffer, |
4869 | cpu_buffer->cpu, ts); | |
7a8e76a3 SR |
4870 | } |
4871 | return event; | |
4872 | ||
4873 | default: | |
da4d401a | 4874 | RB_WARN_ON(cpu_buffer, 1); |
7a8e76a3 SR |
4875 | } |
4876 | ||
4877 | return NULL; | |
4878 | } | |
c4f50183 | 4879 | EXPORT_SYMBOL_GPL(ring_buffer_iter_peek); |
7a8e76a3 | 4880 | |
289a5a25 | 4881 | static inline bool rb_reader_lock(struct ring_buffer_per_cpu *cpu_buffer) |
8d707e8e | 4882 | { |
289a5a25 SRRH |
4883 | if (likely(!in_nmi())) { |
4884 | raw_spin_lock(&cpu_buffer->reader_lock); | |
4885 | return true; | |
4886 | } | |
4887 | ||
8d707e8e SR |
4888 | /* |
4889 | * If an NMI die dumps out the content of the ring buffer | |
289a5a25 SRRH |
4890 | * trylock must be used to prevent a deadlock if the NMI |
4891 | * preempted a task that holds the ring buffer locks. If | |
4892 | * we get the lock then all is fine, if not, then continue | |
4893 | * to do the read, but this can corrupt the ring buffer, | |
4894 | * so it must be permanently disabled from future writes. | |
4895 | * Reading from NMI is a oneshot deal. | |
8d707e8e | 4896 | */ |
289a5a25 SRRH |
4897 | if (raw_spin_trylock(&cpu_buffer->reader_lock)) |
4898 | return true; | |
8d707e8e | 4899 | |
289a5a25 SRRH |
4900 | /* Continue without locking, but disable the ring buffer */ |
4901 | atomic_inc(&cpu_buffer->record_disabled); | |
4902 | return false; | |
4903 | } | |
4904 | ||
4905 | static inline void | |
4906 | rb_reader_unlock(struct ring_buffer_per_cpu *cpu_buffer, bool locked) | |
4907 | { | |
4908 | if (likely(locked)) | |
4909 | raw_spin_unlock(&cpu_buffer->reader_lock); | |
8d707e8e SR |
4910 | } |
4911 | ||
f83c9d0f SR |
4912 | /** |
4913 | * ring_buffer_peek - peek at the next event to be read | |
4914 | * @buffer: The ring buffer to read | |
4915 | * @cpu: The cpu to peak at | |
4916 | * @ts: The timestamp counter of this event. | |
66a8cb95 | 4917 | * @lost_events: a variable to store if events were lost (may be NULL) |
f83c9d0f SR |
4918 | * |
4919 | * This will return the event that will be read next, but does | |
4920 | * not consume the data. | |
4921 | */ | |
4922 | struct ring_buffer_event * | |
13292494 | 4923 | ring_buffer_peek(struct trace_buffer *buffer, int cpu, u64 *ts, |
66a8cb95 | 4924 | unsigned long *lost_events) |
f83c9d0f SR |
4925 | { |
4926 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
8aabee57 | 4927 | struct ring_buffer_event *event; |
f83c9d0f | 4928 | unsigned long flags; |
289a5a25 | 4929 | bool dolock; |
f83c9d0f | 4930 | |
554f786e | 4931 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 4932 | return NULL; |
554f786e | 4933 | |
2d622719 | 4934 | again: |
8d707e8e | 4935 | local_irq_save(flags); |
289a5a25 | 4936 | dolock = rb_reader_lock(cpu_buffer); |
66a8cb95 | 4937 | event = rb_buffer_peek(cpu_buffer, ts, lost_events); |
469535a5 RR |
4938 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
4939 | rb_advance_reader(cpu_buffer); | |
289a5a25 | 4940 | rb_reader_unlock(cpu_buffer, dolock); |
8d707e8e | 4941 | local_irq_restore(flags); |
f83c9d0f | 4942 | |
1b959e18 | 4943 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
2d622719 | 4944 | goto again; |
2d622719 | 4945 | |
f83c9d0f SR |
4946 | return event; |
4947 | } | |
4948 | ||
c9b7a4a7 SRV |
4949 | /** ring_buffer_iter_dropped - report if there are dropped events |
4950 | * @iter: The ring buffer iterator | |
4951 | * | |
4952 | * Returns true if there was dropped events since the last peek. | |
4953 | */ | |
4954 | bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter) | |
4955 | { | |
4956 | bool ret = iter->missed_events != 0; | |
4957 | ||
4958 | iter->missed_events = 0; | |
4959 | return ret; | |
4960 | } | |
4961 | EXPORT_SYMBOL_GPL(ring_buffer_iter_dropped); | |
4962 | ||
f83c9d0f SR |
4963 | /** |
4964 | * ring_buffer_iter_peek - peek at the next event to be read | |
4965 | * @iter: The ring buffer iterator | |
4966 | * @ts: The timestamp counter of this event. | |
4967 | * | |
4968 | * This will return the event that will be read next, but does | |
4969 | * not increment the iterator. | |
4970 | */ | |
4971 | struct ring_buffer_event * | |
4972 | ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) | |
4973 | { | |
4974 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
4975 | struct ring_buffer_event *event; | |
4976 | unsigned long flags; | |
4977 | ||
2d622719 | 4978 | again: |
5389f6fa | 4979 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
f83c9d0f | 4980 | event = rb_iter_peek(iter, ts); |
5389f6fa | 4981 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
f83c9d0f | 4982 | |
1b959e18 | 4983 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
2d622719 | 4984 | goto again; |
2d622719 | 4985 | |
f83c9d0f SR |
4986 | return event; |
4987 | } | |
4988 | ||
7a8e76a3 SR |
4989 | /** |
4990 | * ring_buffer_consume - return an event and consume it | |
4991 | * @buffer: The ring buffer to get the next event from | |
66a8cb95 SR |
4992 | * @cpu: the cpu to read the buffer from |
4993 | * @ts: a variable to store the timestamp (may be NULL) | |
4994 | * @lost_events: a variable to store if events were lost (may be NULL) | |
7a8e76a3 SR |
4995 | * |
4996 | * Returns the next event in the ring buffer, and that event is consumed. | |
4997 | * Meaning, that sequential reads will keep returning a different event, | |
4998 | * and eventually empty the ring buffer if the producer is slower. | |
4999 | */ | |
5000 | struct ring_buffer_event * | |
13292494 | 5001 | ring_buffer_consume(struct trace_buffer *buffer, int cpu, u64 *ts, |
66a8cb95 | 5002 | unsigned long *lost_events) |
7a8e76a3 | 5003 | { |
554f786e SR |
5004 | struct ring_buffer_per_cpu *cpu_buffer; |
5005 | struct ring_buffer_event *event = NULL; | |
f83c9d0f | 5006 | unsigned long flags; |
289a5a25 | 5007 | bool dolock; |
7a8e76a3 | 5008 | |
2d622719 | 5009 | again: |
554f786e SR |
5010 | /* might be called in atomic */ |
5011 | preempt_disable(); | |
5012 | ||
9e01c1b7 | 5013 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
554f786e | 5014 | goto out; |
7a8e76a3 | 5015 | |
554f786e | 5016 | cpu_buffer = buffer->buffers[cpu]; |
8d707e8e | 5017 | local_irq_save(flags); |
289a5a25 | 5018 | dolock = rb_reader_lock(cpu_buffer); |
f83c9d0f | 5019 | |
66a8cb95 SR |
5020 | event = rb_buffer_peek(cpu_buffer, ts, lost_events); |
5021 | if (event) { | |
5022 | cpu_buffer->lost_events = 0; | |
469535a5 | 5023 | rb_advance_reader(cpu_buffer); |
66a8cb95 | 5024 | } |
7a8e76a3 | 5025 | |
289a5a25 | 5026 | rb_reader_unlock(cpu_buffer, dolock); |
8d707e8e | 5027 | local_irq_restore(flags); |
f83c9d0f | 5028 | |
554f786e SR |
5029 | out: |
5030 | preempt_enable(); | |
5031 | ||
1b959e18 | 5032 | if (event && event->type_len == RINGBUF_TYPE_PADDING) |
2d622719 | 5033 | goto again; |
2d622719 | 5034 | |
7a8e76a3 SR |
5035 | return event; |
5036 | } | |
c4f50183 | 5037 | EXPORT_SYMBOL_GPL(ring_buffer_consume); |
7a8e76a3 SR |
5038 | |
5039 | /** | |
72c9ddfd | 5040 | * ring_buffer_read_prepare - Prepare for a non consuming read of the buffer |
7a8e76a3 SR |
5041 | * @buffer: The ring buffer to read from |
5042 | * @cpu: The cpu buffer to iterate over | |
31b265b3 | 5043 | * @flags: gfp flags to use for memory allocation |
7a8e76a3 | 5044 | * |
72c9ddfd | 5045 | * This performs the initial preparations necessary to iterate |
ea70a962 | 5046 | * through the buffer. Memory is allocated, buffer resizing |
72c9ddfd | 5047 | * is disabled, and the iterator pointer is returned to the caller. |
7a8e76a3 | 5048 | * |
72c9ddfd | 5049 | * After a sequence of ring_buffer_read_prepare calls, the user is |
d611851b | 5050 | * expected to make at least one call to ring_buffer_read_prepare_sync. |
72c9ddfd DM |
5051 | * Afterwards, ring_buffer_read_start is invoked to get things going |
5052 | * for real. | |
5053 | * | |
d611851b | 5054 | * This overall must be paired with ring_buffer_read_finish. |
7a8e76a3 SR |
5055 | */ |
5056 | struct ring_buffer_iter * | |
13292494 | 5057 | ring_buffer_read_prepare(struct trace_buffer *buffer, int cpu, gfp_t flags) |
7a8e76a3 SR |
5058 | { |
5059 | struct ring_buffer_per_cpu *cpu_buffer; | |
8aabee57 | 5060 | struct ring_buffer_iter *iter; |
7a8e76a3 | 5061 | |
9e01c1b7 | 5062 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 5063 | return NULL; |
7a8e76a3 | 5064 | |
785888c5 | 5065 | iter = kzalloc(sizeof(*iter), flags); |
7a8e76a3 | 5066 | if (!iter) |
8aabee57 | 5067 | return NULL; |
7a8e76a3 | 5068 | |
b0495258 | 5069 | /* Holds the entire event: data and meta data */ |
139f8400 TSV |
5070 | iter->event_size = buffer->subbuf_size; |
5071 | iter->event = kmalloc(iter->event_size, flags); | |
785888c5 SRV |
5072 | if (!iter->event) { |
5073 | kfree(iter); | |
5074 | return NULL; | |
5075 | } | |
5076 | ||
7a8e76a3 SR |
5077 | cpu_buffer = buffer->buffers[cpu]; |
5078 | ||
5079 | iter->cpu_buffer = cpu_buffer; | |
5080 | ||
07b8b10e | 5081 | atomic_inc(&cpu_buffer->resize_disabled); |
72c9ddfd DM |
5082 | |
5083 | return iter; | |
5084 | } | |
5085 | EXPORT_SYMBOL_GPL(ring_buffer_read_prepare); | |
5086 | ||
5087 | /** | |
5088 | * ring_buffer_read_prepare_sync - Synchronize a set of prepare calls | |
5089 | * | |
5090 | * All previously invoked ring_buffer_read_prepare calls to prepare | |
5091 | * iterators will be synchronized. Afterwards, read_buffer_read_start | |
5092 | * calls on those iterators are allowed. | |
5093 | */ | |
5094 | void | |
5095 | ring_buffer_read_prepare_sync(void) | |
5096 | { | |
74401729 | 5097 | synchronize_rcu(); |
72c9ddfd DM |
5098 | } |
5099 | EXPORT_SYMBOL_GPL(ring_buffer_read_prepare_sync); | |
5100 | ||
5101 | /** | |
5102 | * ring_buffer_read_start - start a non consuming read of the buffer | |
5103 | * @iter: The iterator returned by ring_buffer_read_prepare | |
5104 | * | |
5105 | * This finalizes the startup of an iteration through the buffer. | |
5106 | * The iterator comes from a call to ring_buffer_read_prepare and | |
5107 | * an intervening ring_buffer_read_prepare_sync must have been | |
5108 | * performed. | |
5109 | * | |
d611851b | 5110 | * Must be paired with ring_buffer_read_finish. |
72c9ddfd DM |
5111 | */ |
5112 | void | |
5113 | ring_buffer_read_start(struct ring_buffer_iter *iter) | |
5114 | { | |
5115 | struct ring_buffer_per_cpu *cpu_buffer; | |
5116 | unsigned long flags; | |
5117 | ||
5118 | if (!iter) | |
5119 | return; | |
5120 | ||
5121 | cpu_buffer = iter->cpu_buffer; | |
7a8e76a3 | 5122 | |
5389f6fa | 5123 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
0199c4e6 | 5124 | arch_spin_lock(&cpu_buffer->lock); |
642edba5 | 5125 | rb_iter_reset(iter); |
0199c4e6 | 5126 | arch_spin_unlock(&cpu_buffer->lock); |
5389f6fa | 5127 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
7a8e76a3 | 5128 | } |
c4f50183 | 5129 | EXPORT_SYMBOL_GPL(ring_buffer_read_start); |
7a8e76a3 SR |
5130 | |
5131 | /** | |
d611851b | 5132 | * ring_buffer_read_finish - finish reading the iterator of the buffer |
7a8e76a3 SR |
5133 | * @iter: The iterator retrieved by ring_buffer_start |
5134 | * | |
ea70a962 | 5135 | * This re-enables resizing of the buffer, and frees the iterator. |
7a8e76a3 SR |
5136 | */ |
5137 | void | |
5138 | ring_buffer_read_finish(struct ring_buffer_iter *iter) | |
5139 | { | |
5140 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; | |
9366c1ba | 5141 | unsigned long flags; |
7a8e76a3 | 5142 | |
ea70a962 | 5143 | /* Use this opportunity to check the integrity of the ring buffer. */ |
9366c1ba | 5144 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
659f451f | 5145 | rb_check_pages(cpu_buffer); |
9366c1ba | 5146 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
659f451f | 5147 | |
07b8b10e | 5148 | atomic_dec(&cpu_buffer->resize_disabled); |
785888c5 | 5149 | kfree(iter->event); |
7a8e76a3 SR |
5150 | kfree(iter); |
5151 | } | |
c4f50183 | 5152 | EXPORT_SYMBOL_GPL(ring_buffer_read_finish); |
7a8e76a3 SR |
5153 | |
5154 | /** | |
bc1a72af | 5155 | * ring_buffer_iter_advance - advance the iterator to the next location |
7a8e76a3 | 5156 | * @iter: The ring buffer iterator |
7a8e76a3 | 5157 | * |
bc1a72af SRV |
5158 | * Move the location of the iterator such that the next read will |
5159 | * be the next location of the iterator. | |
7a8e76a3 | 5160 | */ |
bc1a72af | 5161 | void ring_buffer_iter_advance(struct ring_buffer_iter *iter) |
7a8e76a3 | 5162 | { |
f83c9d0f SR |
5163 | struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; |
5164 | unsigned long flags; | |
7a8e76a3 | 5165 | |
5389f6fa | 5166 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
7e9391cf | 5167 | |
7a8e76a3 SR |
5168 | rb_advance_iter(iter); |
5169 | ||
bc1a72af | 5170 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
7a8e76a3 | 5171 | } |
bc1a72af | 5172 | EXPORT_SYMBOL_GPL(ring_buffer_iter_advance); |
7a8e76a3 SR |
5173 | |
5174 | /** | |
5175 | * ring_buffer_size - return the size of the ring buffer (in bytes) | |
5176 | * @buffer: The ring buffer. | |
59e7cffe | 5177 | * @cpu: The CPU to get ring buffer size from. |
7a8e76a3 | 5178 | */ |
13292494 | 5179 | unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu) |
7a8e76a3 | 5180 | { |
438ced17 VN |
5181 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
5182 | return 0; | |
5183 | ||
139f8400 | 5184 | return buffer->subbuf_size * buffer->buffers[cpu]->nr_pages; |
7a8e76a3 | 5185 | } |
c4f50183 | 5186 | EXPORT_SYMBOL_GPL(ring_buffer_size); |
7a8e76a3 | 5187 | |
8ec90be7 SRG |
5188 | /** |
5189 | * ring_buffer_max_event_size - return the max data size of an event | |
5190 | * @buffer: The ring buffer. | |
5191 | * | |
5192 | * Returns the maximum size an event can be. | |
5193 | */ | |
5194 | unsigned long ring_buffer_max_event_size(struct trace_buffer *buffer) | |
5195 | { | |
5196 | /* If abs timestamp is requested, events have a timestamp too */ | |
5197 | if (ring_buffer_time_stamp_abs(buffer)) | |
139f8400 TSV |
5198 | return buffer->max_data_size - RB_LEN_TIME_EXTEND; |
5199 | return buffer->max_data_size; | |
8ec90be7 SRG |
5200 | } |
5201 | EXPORT_SYMBOL_GPL(ring_buffer_max_event_size); | |
5202 | ||
7e42907f ZY |
5203 | static void rb_clear_buffer_page(struct buffer_page *page) |
5204 | { | |
5205 | local_set(&page->write, 0); | |
5206 | local_set(&page->entries, 0); | |
5207 | rb_init_page(page->page); | |
5208 | page->read = 0; | |
5209 | } | |
5210 | ||
117c3920 VD |
5211 | static void rb_update_meta_page(struct ring_buffer_per_cpu *cpu_buffer) |
5212 | { | |
5213 | struct trace_buffer_meta *meta = cpu_buffer->meta_page; | |
5214 | ||
5215 | meta->reader.read = cpu_buffer->reader_page->read; | |
5216 | meta->reader.id = cpu_buffer->reader_page->id; | |
5217 | meta->reader.lost_events = cpu_buffer->lost_events; | |
5218 | ||
5219 | meta->entries = local_read(&cpu_buffer->entries); | |
5220 | meta->overrun = local_read(&cpu_buffer->overrun); | |
5221 | meta->read = cpu_buffer->read; | |
5222 | ||
5223 | /* Some archs do not have data cache coherency between kernel and user-space */ | |
5224 | flush_dcache_folio(virt_to_folio(cpu_buffer->meta_page)); | |
5225 | } | |
5226 | ||
7a8e76a3 SR |
5227 | static void |
5228 | rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) | |
5229 | { | |
7e42907f ZY |
5230 | struct buffer_page *page; |
5231 | ||
77ae365e SR |
5232 | rb_head_page_deactivate(cpu_buffer); |
5233 | ||
7a8e76a3 | 5234 | cpu_buffer->head_page |
3adc54fa | 5235 | = list_entry(cpu_buffer->pages, struct buffer_page, list); |
7e42907f ZY |
5236 | rb_clear_buffer_page(cpu_buffer->head_page); |
5237 | list_for_each_entry(page, cpu_buffer->pages, list) { | |
5238 | rb_clear_buffer_page(page); | |
5239 | } | |
bf41a158 SR |
5240 | |
5241 | cpu_buffer->tail_page = cpu_buffer->head_page; | |
5242 | cpu_buffer->commit_page = cpu_buffer->head_page; | |
5243 | ||
5244 | INIT_LIST_HEAD(&cpu_buffer->reader_page->list); | |
5040b4b7 | 5245 | INIT_LIST_HEAD(&cpu_buffer->new_pages); |
7e42907f | 5246 | rb_clear_buffer_page(cpu_buffer->reader_page); |
7a8e76a3 | 5247 | |
c64e148a | 5248 | local_set(&cpu_buffer->entries_bytes, 0); |
77ae365e | 5249 | local_set(&cpu_buffer->overrun, 0); |
884bfe89 SP |
5250 | local_set(&cpu_buffer->commit_overrun, 0); |
5251 | local_set(&cpu_buffer->dropped_events, 0); | |
e4906eff | 5252 | local_set(&cpu_buffer->entries, 0); |
fa743953 SR |
5253 | local_set(&cpu_buffer->committing, 0); |
5254 | local_set(&cpu_buffer->commits, 0); | |
2c2b0a78 | 5255 | local_set(&cpu_buffer->pages_touched, 0); |
31029a8b | 5256 | local_set(&cpu_buffer->pages_lost, 0); |
2c2b0a78 | 5257 | local_set(&cpu_buffer->pages_read, 0); |
03329f99 | 5258 | cpu_buffer->last_pages_touch = 0; |
2c2b0a78 | 5259 | cpu_buffer->shortest_full = 0; |
77ae365e | 5260 | cpu_buffer->read = 0; |
c64e148a | 5261 | cpu_buffer->read_bytes = 0; |
69507c06 | 5262 | |
10464b4a SRV |
5263 | rb_time_set(&cpu_buffer->write_stamp, 0); |
5264 | rb_time_set(&cpu_buffer->before_stamp, 0); | |
77ae365e | 5265 | |
8672e494 SRV |
5266 | memset(cpu_buffer->event_stamp, 0, sizeof(cpu_buffer->event_stamp)); |
5267 | ||
66a8cb95 SR |
5268 | cpu_buffer->lost_events = 0; |
5269 | cpu_buffer->last_overrun = 0; | |
5270 | ||
117c3920 VD |
5271 | if (cpu_buffer->mapped) |
5272 | rb_update_meta_page(cpu_buffer); | |
5273 | ||
77ae365e | 5274 | rb_head_page_activate(cpu_buffer); |
2d093282 | 5275 | cpu_buffer->pages_removed = 0; |
7a8e76a3 SR |
5276 | } |
5277 | ||
b23d7a5f NP |
5278 | /* Must have disabled the cpu buffer then done a synchronize_rcu */ |
5279 | static void reset_disabled_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) | |
5280 | { | |
5281 | unsigned long flags; | |
5282 | ||
5283 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
5284 | ||
5285 | if (RB_WARN_ON(cpu_buffer, local_read(&cpu_buffer->committing))) | |
5286 | goto out; | |
5287 | ||
5288 | arch_spin_lock(&cpu_buffer->lock); | |
5289 | ||
5290 | rb_reset_cpu(cpu_buffer); | |
5291 | ||
5292 | arch_spin_unlock(&cpu_buffer->lock); | |
5293 | ||
5294 | out: | |
5295 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
5296 | } | |
5297 | ||
7a8e76a3 SR |
5298 | /** |
5299 | * ring_buffer_reset_cpu - reset a ring buffer per CPU buffer | |
5300 | * @buffer: The ring buffer to reset a per cpu buffer of | |
5301 | * @cpu: The CPU buffer to be reset | |
5302 | */ | |
13292494 | 5303 | void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu) |
7a8e76a3 SR |
5304 | { |
5305 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 | 5306 | |
9e01c1b7 | 5307 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
8aabee57 | 5308 | return; |
7a8e76a3 | 5309 | |
bbeb9746 GK |
5310 | /* prevent another thread from changing buffer sizes */ |
5311 | mutex_lock(&buffer->mutex); | |
5312 | ||
07b8b10e | 5313 | atomic_inc(&cpu_buffer->resize_disabled); |
41ede23e SR |
5314 | atomic_inc(&cpu_buffer->record_disabled); |
5315 | ||
83f40318 | 5316 | /* Make sure all commits have finished */ |
74401729 | 5317 | synchronize_rcu(); |
83f40318 | 5318 | |
b23d7a5f | 5319 | reset_disabled_cpu_buffer(cpu_buffer); |
f83c9d0f | 5320 | |
b23d7a5f NP |
5321 | atomic_dec(&cpu_buffer->record_disabled); |
5322 | atomic_dec(&cpu_buffer->resize_disabled); | |
bbeb9746 GK |
5323 | |
5324 | mutex_unlock(&buffer->mutex); | |
b23d7a5f NP |
5325 | } |
5326 | EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); | |
41b6a95d | 5327 | |
7c339fb4 TW |
5328 | /* Flag to ensure proper resetting of atomic variables */ |
5329 | #define RESET_BIT (1 << 30) | |
5330 | ||
b23d7a5f | 5331 | /** |
b7085b6f | 5332 | * ring_buffer_reset_online_cpus - reset a ring buffer per CPU buffer |
b23d7a5f | 5333 | * @buffer: The ring buffer to reset a per cpu buffer of |
b23d7a5f NP |
5334 | */ |
5335 | void ring_buffer_reset_online_cpus(struct trace_buffer *buffer) | |
5336 | { | |
5337 | struct ring_buffer_per_cpu *cpu_buffer; | |
5338 | int cpu; | |
7a8e76a3 | 5339 | |
bbeb9746 GK |
5340 | /* prevent another thread from changing buffer sizes */ |
5341 | mutex_lock(&buffer->mutex); | |
5342 | ||
b23d7a5f NP |
5343 | for_each_online_buffer_cpu(buffer, cpu) { |
5344 | cpu_buffer = buffer->buffers[cpu]; | |
7a8e76a3 | 5345 | |
7c339fb4 | 5346 | atomic_add(RESET_BIT, &cpu_buffer->resize_disabled); |
b23d7a5f NP |
5347 | atomic_inc(&cpu_buffer->record_disabled); |
5348 | } | |
f83c9d0f | 5349 | |
b23d7a5f NP |
5350 | /* Make sure all commits have finished */ |
5351 | synchronize_rcu(); | |
41ede23e | 5352 | |
7c339fb4 | 5353 | for_each_buffer_cpu(buffer, cpu) { |
b23d7a5f NP |
5354 | cpu_buffer = buffer->buffers[cpu]; |
5355 | ||
7c339fb4 TW |
5356 | /* |
5357 | * If a CPU came online during the synchronize_rcu(), then | |
5358 | * ignore it. | |
5359 | */ | |
5360 | if (!(atomic_read(&cpu_buffer->resize_disabled) & RESET_BIT)) | |
5361 | continue; | |
5362 | ||
b23d7a5f NP |
5363 | reset_disabled_cpu_buffer(cpu_buffer); |
5364 | ||
5365 | atomic_dec(&cpu_buffer->record_disabled); | |
7c339fb4 | 5366 | atomic_sub(RESET_BIT, &cpu_buffer->resize_disabled); |
b23d7a5f | 5367 | } |
bbeb9746 GK |
5368 | |
5369 | mutex_unlock(&buffer->mutex); | |
7a8e76a3 SR |
5370 | } |
5371 | ||
5372 | /** | |
5373 | * ring_buffer_reset - reset a ring buffer | |
5374 | * @buffer: The ring buffer to reset all cpu buffers | |
5375 | */ | |
13292494 | 5376 | void ring_buffer_reset(struct trace_buffer *buffer) |
7a8e76a3 | 5377 | { |
b23d7a5f | 5378 | struct ring_buffer_per_cpu *cpu_buffer; |
7a8e76a3 SR |
5379 | int cpu; |
5380 | ||
51d15794 SRV |
5381 | /* prevent another thread from changing buffer sizes */ |
5382 | mutex_lock(&buffer->mutex); | |
5383 | ||
b23d7a5f NP |
5384 | for_each_buffer_cpu(buffer, cpu) { |
5385 | cpu_buffer = buffer->buffers[cpu]; | |
5386 | ||
5387 | atomic_inc(&cpu_buffer->resize_disabled); | |
5388 | atomic_inc(&cpu_buffer->record_disabled); | |
5389 | } | |
5390 | ||
5391 | /* Make sure all commits have finished */ | |
5392 | synchronize_rcu(); | |
5393 | ||
5394 | for_each_buffer_cpu(buffer, cpu) { | |
5395 | cpu_buffer = buffer->buffers[cpu]; | |
5396 | ||
5397 | reset_disabled_cpu_buffer(cpu_buffer); | |
5398 | ||
5399 | atomic_dec(&cpu_buffer->record_disabled); | |
5400 | atomic_dec(&cpu_buffer->resize_disabled); | |
5401 | } | |
51d15794 SRV |
5402 | |
5403 | mutex_unlock(&buffer->mutex); | |
7a8e76a3 | 5404 | } |
c4f50183 | 5405 | EXPORT_SYMBOL_GPL(ring_buffer_reset); |
7a8e76a3 SR |
5406 | |
5407 | /** | |
b7085b6f | 5408 | * ring_buffer_empty - is the ring buffer empty? |
7a8e76a3 SR |
5409 | * @buffer: The ring buffer to test |
5410 | */ | |
13292494 | 5411 | bool ring_buffer_empty(struct trace_buffer *buffer) |
7a8e76a3 SR |
5412 | { |
5413 | struct ring_buffer_per_cpu *cpu_buffer; | |
d4788207 | 5414 | unsigned long flags; |
289a5a25 | 5415 | bool dolock; |
bc92b956 | 5416 | bool ret; |
7a8e76a3 SR |
5417 | int cpu; |
5418 | ||
5419 | /* yes this is racy, but if you don't like the race, lock the buffer */ | |
5420 | for_each_buffer_cpu(buffer, cpu) { | |
5421 | cpu_buffer = buffer->buffers[cpu]; | |
8d707e8e | 5422 | local_irq_save(flags); |
289a5a25 | 5423 | dolock = rb_reader_lock(cpu_buffer); |
d4788207 | 5424 | ret = rb_per_cpu_empty(cpu_buffer); |
289a5a25 | 5425 | rb_reader_unlock(cpu_buffer, dolock); |
8d707e8e SR |
5426 | local_irq_restore(flags); |
5427 | ||
d4788207 | 5428 | if (!ret) |
3d4e204d | 5429 | return false; |
7a8e76a3 | 5430 | } |
554f786e | 5431 | |
3d4e204d | 5432 | return true; |
7a8e76a3 | 5433 | } |
c4f50183 | 5434 | EXPORT_SYMBOL_GPL(ring_buffer_empty); |
7a8e76a3 SR |
5435 | |
5436 | /** | |
5437 | * ring_buffer_empty_cpu - is a cpu buffer of a ring buffer empty? | |
5438 | * @buffer: The ring buffer | |
5439 | * @cpu: The CPU buffer to test | |
5440 | */ | |
13292494 | 5441 | bool ring_buffer_empty_cpu(struct trace_buffer *buffer, int cpu) |
7a8e76a3 SR |
5442 | { |
5443 | struct ring_buffer_per_cpu *cpu_buffer; | |
d4788207 | 5444 | unsigned long flags; |
289a5a25 | 5445 | bool dolock; |
bc92b956 | 5446 | bool ret; |
7a8e76a3 | 5447 | |
9e01c1b7 | 5448 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
3d4e204d | 5449 | return true; |
7a8e76a3 SR |
5450 | |
5451 | cpu_buffer = buffer->buffers[cpu]; | |
8d707e8e | 5452 | local_irq_save(flags); |
289a5a25 | 5453 | dolock = rb_reader_lock(cpu_buffer); |
554f786e | 5454 | ret = rb_per_cpu_empty(cpu_buffer); |
289a5a25 | 5455 | rb_reader_unlock(cpu_buffer, dolock); |
8d707e8e | 5456 | local_irq_restore(flags); |
554f786e SR |
5457 | |
5458 | return ret; | |
7a8e76a3 | 5459 | } |
c4f50183 | 5460 | EXPORT_SYMBOL_GPL(ring_buffer_empty_cpu); |
7a8e76a3 | 5461 | |
85bac32c | 5462 | #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP |
7a8e76a3 SR |
5463 | /** |
5464 | * ring_buffer_swap_cpu - swap a CPU buffer between two ring buffers | |
5465 | * @buffer_a: One buffer to swap with | |
5466 | * @buffer_b: The other buffer to swap with | |
59e7cffe | 5467 | * @cpu: the CPU of the buffers to swap |
7a8e76a3 SR |
5468 | * |
5469 | * This function is useful for tracers that want to take a "snapshot" | |
5470 | * of a CPU buffer and has another back up buffer lying around. | |
5471 | * it is expected that the tracer handles the cpu buffer not being | |
5472 | * used at the moment. | |
5473 | */ | |
13292494 SRV |
5474 | int ring_buffer_swap_cpu(struct trace_buffer *buffer_a, |
5475 | struct trace_buffer *buffer_b, int cpu) | |
7a8e76a3 SR |
5476 | { |
5477 | struct ring_buffer_per_cpu *cpu_buffer_a; | |
5478 | struct ring_buffer_per_cpu *cpu_buffer_b; | |
554f786e SR |
5479 | int ret = -EINVAL; |
5480 | ||
9e01c1b7 RR |
5481 | if (!cpumask_test_cpu(cpu, buffer_a->cpumask) || |
5482 | !cpumask_test_cpu(cpu, buffer_b->cpumask)) | |
554f786e | 5483 | goto out; |
7a8e76a3 | 5484 | |
438ced17 VN |
5485 | cpu_buffer_a = buffer_a->buffers[cpu]; |
5486 | cpu_buffer_b = buffer_b->buffers[cpu]; | |
5487 | ||
117c3920 VD |
5488 | /* It's up to the callers to not try to swap mapped buffers */ |
5489 | if (WARN_ON_ONCE(cpu_buffer_a->mapped || cpu_buffer_b->mapped)) { | |
5490 | ret = -EBUSY; | |
5491 | goto out; | |
5492 | } | |
5493 | ||
7a8e76a3 | 5494 | /* At least make sure the two buffers are somewhat the same */ |
438ced17 | 5495 | if (cpu_buffer_a->nr_pages != cpu_buffer_b->nr_pages) |
554f786e SR |
5496 | goto out; |
5497 | ||
b81e03a2 SRG |
5498 | if (buffer_a->subbuf_order != buffer_b->subbuf_order) |
5499 | goto out; | |
5500 | ||
554f786e | 5501 | ret = -EAGAIN; |
7a8e76a3 | 5502 | |
97b17efe | 5503 | if (atomic_read(&buffer_a->record_disabled)) |
554f786e | 5504 | goto out; |
97b17efe SR |
5505 | |
5506 | if (atomic_read(&buffer_b->record_disabled)) | |
554f786e | 5507 | goto out; |
97b17efe | 5508 | |
97b17efe | 5509 | if (atomic_read(&cpu_buffer_a->record_disabled)) |
554f786e | 5510 | goto out; |
97b17efe SR |
5511 | |
5512 | if (atomic_read(&cpu_buffer_b->record_disabled)) | |
554f786e | 5513 | goto out; |
97b17efe | 5514 | |
7a8e76a3 | 5515 | /* |
74401729 | 5516 | * We can't do a synchronize_rcu here because this |
7a8e76a3 SR |
5517 | * function can be called in atomic context. |
5518 | * Normally this will be called from the same CPU as cpu. | |
5519 | * If not it's up to the caller to protect this. | |
5520 | */ | |
5521 | atomic_inc(&cpu_buffer_a->record_disabled); | |
5522 | atomic_inc(&cpu_buffer_b->record_disabled); | |
5523 | ||
98277991 SR |
5524 | ret = -EBUSY; |
5525 | if (local_read(&cpu_buffer_a->committing)) | |
5526 | goto out_dec; | |
5527 | if (local_read(&cpu_buffer_b->committing)) | |
5528 | goto out_dec; | |
5529 | ||
8a96c028 CL |
5530 | /* |
5531 | * When resize is in progress, we cannot swap it because | |
5532 | * it will mess the state of the cpu buffer. | |
5533 | */ | |
5534 | if (atomic_read(&buffer_a->resizing)) | |
5535 | goto out_dec; | |
5536 | if (atomic_read(&buffer_b->resizing)) | |
5537 | goto out_dec; | |
5538 | ||
7a8e76a3 SR |
5539 | buffer_a->buffers[cpu] = cpu_buffer_b; |
5540 | buffer_b->buffers[cpu] = cpu_buffer_a; | |
5541 | ||
5542 | cpu_buffer_b->buffer = buffer_a; | |
5543 | cpu_buffer_a->buffer = buffer_b; | |
5544 | ||
98277991 SR |
5545 | ret = 0; |
5546 | ||
5547 | out_dec: | |
7a8e76a3 SR |
5548 | atomic_dec(&cpu_buffer_a->record_disabled); |
5549 | atomic_dec(&cpu_buffer_b->record_disabled); | |
554f786e | 5550 | out: |
554f786e | 5551 | return ret; |
7a8e76a3 | 5552 | } |
c4f50183 | 5553 | EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu); |
85bac32c | 5554 | #endif /* CONFIG_RING_BUFFER_ALLOW_SWAP */ |
7a8e76a3 | 5555 | |
8789a9e7 SR |
5556 | /** |
5557 | * ring_buffer_alloc_read_page - allocate a page to read from buffer | |
5558 | * @buffer: the buffer to allocate for. | |
d611851b | 5559 | * @cpu: the cpu buffer to allocate. |
8789a9e7 SR |
5560 | * |
5561 | * This function is used in conjunction with ring_buffer_read_page. | |
5562 | * When reading a full page from the ring buffer, these functions | |
5563 | * can be used to speed up the process. The calling function should | |
5564 | * allocate a few pages first with this function. Then when it | |
5565 | * needs to get pages from the ring buffer, it passes the result | |
5566 | * of this function into ring_buffer_read_page, which will swap | |
5567 | * the page that was allocated, with the read page of the buffer. | |
5568 | * | |
5569 | * Returns: | |
a7e52ad7 | 5570 | * The page allocated, or ERR_PTR |
8789a9e7 | 5571 | */ |
bce761d7 TSV |
5572 | struct buffer_data_read_page * |
5573 | ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu) | |
8789a9e7 | 5574 | { |
a7e52ad7 | 5575 | struct ring_buffer_per_cpu *cpu_buffer; |
bce761d7 | 5576 | struct buffer_data_read_page *bpage = NULL; |
73a757e6 | 5577 | unsigned long flags; |
7ea59064 | 5578 | struct page *page; |
8789a9e7 | 5579 | |
a7e52ad7 SRV |
5580 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
5581 | return ERR_PTR(-ENODEV); | |
5582 | ||
bce761d7 TSV |
5583 | bpage = kzalloc(sizeof(*bpage), GFP_KERNEL); |
5584 | if (!bpage) | |
5585 | return ERR_PTR(-ENOMEM); | |
5586 | ||
5587 | bpage->order = buffer->subbuf_order; | |
a7e52ad7 | 5588 | cpu_buffer = buffer->buffers[cpu]; |
73a757e6 SRV |
5589 | local_irq_save(flags); |
5590 | arch_spin_lock(&cpu_buffer->lock); | |
5591 | ||
5592 | if (cpu_buffer->free_page) { | |
bce761d7 | 5593 | bpage->data = cpu_buffer->free_page; |
73a757e6 SRV |
5594 | cpu_buffer->free_page = NULL; |
5595 | } | |
5596 | ||
5597 | arch_spin_unlock(&cpu_buffer->lock); | |
5598 | local_irq_restore(flags); | |
5599 | ||
bce761d7 | 5600 | if (bpage->data) |
73a757e6 SRV |
5601 | goto out; |
5602 | ||
6b76323e | 5603 | page = alloc_pages_node(cpu_to_node(cpu), |
c09d4167 | 5604 | GFP_KERNEL | __GFP_NORETRY | __GFP_COMP | __GFP_ZERO, |
f9b94daa | 5605 | cpu_buffer->buffer->subbuf_order); |
bce761d7 TSV |
5606 | if (!page) { |
5607 | kfree(bpage); | |
a7e52ad7 | 5608 | return ERR_PTR(-ENOMEM); |
bce761d7 | 5609 | } |
8789a9e7 | 5610 | |
bce761d7 | 5611 | bpage->data = page_address(page); |
8789a9e7 | 5612 | |
73a757e6 | 5613 | out: |
bce761d7 | 5614 | rb_init_page(bpage->data); |
ef7a4a16 | 5615 | |
044fa782 | 5616 | return bpage; |
8789a9e7 | 5617 | } |
d6ce96da | 5618 | EXPORT_SYMBOL_GPL(ring_buffer_alloc_read_page); |
8789a9e7 SR |
5619 | |
5620 | /** | |
5621 | * ring_buffer_free_read_page - free an allocated read page | |
5622 | * @buffer: the buffer the page was allocate for | |
73a757e6 | 5623 | * @cpu: the cpu buffer the page came from |
bce761d7 | 5624 | * @data_page: the page to free |
8789a9e7 SR |
5625 | * |
5626 | * Free a page allocated from ring_buffer_alloc_read_page. | |
5627 | */ | |
bce761d7 TSV |
5628 | void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu, |
5629 | struct buffer_data_read_page *data_page) | |
8789a9e7 | 5630 | { |
3e4272b9 | 5631 | struct ring_buffer_per_cpu *cpu_buffer; |
bce761d7 | 5632 | struct buffer_data_page *bpage = data_page->data; |
ae415fa4 | 5633 | struct page *page = virt_to_page(bpage); |
73a757e6 SRV |
5634 | unsigned long flags; |
5635 | ||
3e4272b9 JJB |
5636 | if (!buffer || !buffer->buffers || !buffer->buffers[cpu]) |
5637 | return; | |
5638 | ||
5639 | cpu_buffer = buffer->buffers[cpu]; | |
5640 | ||
bce761d7 TSV |
5641 | /* |
5642 | * If the page is still in use someplace else, or order of the page | |
5643 | * is different from the subbuffer order of the buffer - | |
5644 | * we can't reuse it | |
5645 | */ | |
5646 | if (page_ref_count(page) > 1 || data_page->order != buffer->subbuf_order) | |
ae415fa4 SRV |
5647 | goto out; |
5648 | ||
73a757e6 SRV |
5649 | local_irq_save(flags); |
5650 | arch_spin_lock(&cpu_buffer->lock); | |
5651 | ||
5652 | if (!cpu_buffer->free_page) { | |
5653 | cpu_buffer->free_page = bpage; | |
5654 | bpage = NULL; | |
5655 | } | |
5656 | ||
5657 | arch_spin_unlock(&cpu_buffer->lock); | |
5658 | local_irq_restore(flags); | |
5659 | ||
ae415fa4 | 5660 | out: |
bce761d7 TSV |
5661 | free_pages((unsigned long)bpage, data_page->order); |
5662 | kfree(data_page); | |
8789a9e7 | 5663 | } |
d6ce96da | 5664 | EXPORT_SYMBOL_GPL(ring_buffer_free_read_page); |
8789a9e7 SR |
5665 | |
5666 | /** | |
5667 | * ring_buffer_read_page - extract a page from the ring buffer | |
5668 | * @buffer: buffer to extract from | |
5669 | * @data_page: the page to use allocated from ring_buffer_alloc_read_page | |
ef7a4a16 | 5670 | * @len: amount to extract |
8789a9e7 SR |
5671 | * @cpu: the cpu of the buffer to extract |
5672 | * @full: should the extraction only happen when the page is full. | |
5673 | * | |
5674 | * This function will pull out a page from the ring buffer and consume it. | |
5675 | * @data_page must be the address of the variable that was returned | |
5676 | * from ring_buffer_alloc_read_page. This is because the page might be used | |
5677 | * to swap with a page in the ring buffer. | |
5678 | * | |
5679 | * for example: | |
d611851b | 5680 | * rpage = ring_buffer_alloc_read_page(buffer, cpu); |
a7e52ad7 SRV |
5681 | * if (IS_ERR(rpage)) |
5682 | * return PTR_ERR(rpage); | |
bce761d7 | 5683 | * ret = ring_buffer_read_page(buffer, rpage, len, cpu, 0); |
667d2412 | 5684 | * if (ret >= 0) |
bce761d7 TSV |
5685 | * process_page(ring_buffer_read_page_data(rpage), ret); |
5686 | * ring_buffer_free_read_page(buffer, cpu, rpage); | |
8789a9e7 SR |
5687 | * |
5688 | * When @full is set, the function will not return true unless | |
5689 | * the writer is off the reader page. | |
5690 | * | |
5691 | * Note: it is up to the calling functions to handle sleeps and wakeups. | |
5692 | * The ring buffer can be used anywhere in the kernel and can not | |
5693 | * blindly call wake_up. The layer that uses the ring buffer must be | |
5694 | * responsible for that. | |
5695 | * | |
5696 | * Returns: | |
667d2412 LJ |
5697 | * >=0 if data has been transferred, returns the offset of consumed data. |
5698 | * <0 if no data has been transferred. | |
8789a9e7 | 5699 | */ |
13292494 | 5700 | int ring_buffer_read_page(struct trace_buffer *buffer, |
bce761d7 TSV |
5701 | struct buffer_data_read_page *data_page, |
5702 | size_t len, int cpu, int full) | |
8789a9e7 SR |
5703 | { |
5704 | struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; | |
5705 | struct ring_buffer_event *event; | |
044fa782 | 5706 | struct buffer_data_page *bpage; |
ef7a4a16 | 5707 | struct buffer_page *reader; |
ff0ff84a | 5708 | unsigned long missed_events; |
8789a9e7 | 5709 | unsigned long flags; |
ef7a4a16 | 5710 | unsigned int commit; |
667d2412 | 5711 | unsigned int read; |
4f3640f8 | 5712 | u64 save_timestamp; |
667d2412 | 5713 | int ret = -1; |
8789a9e7 | 5714 | |
554f786e SR |
5715 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
5716 | goto out; | |
5717 | ||
474d32b6 SR |
5718 | /* |
5719 | * If len is not big enough to hold the page header, then | |
5720 | * we can not copy anything. | |
5721 | */ | |
5722 | if (len <= BUF_PAGE_HDR_SIZE) | |
554f786e | 5723 | goto out; |
474d32b6 SR |
5724 | |
5725 | len -= BUF_PAGE_HDR_SIZE; | |
5726 | ||
bce761d7 TSV |
5727 | if (!data_page || !data_page->data) |
5728 | goto out; | |
5729 | if (data_page->order != buffer->subbuf_order) | |
554f786e | 5730 | goto out; |
8789a9e7 | 5731 | |
bce761d7 | 5732 | bpage = data_page->data; |
044fa782 | 5733 | if (!bpage) |
554f786e | 5734 | goto out; |
8789a9e7 | 5735 | |
5389f6fa | 5736 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); |
8789a9e7 | 5737 | |
ef7a4a16 SR |
5738 | reader = rb_get_reader_page(cpu_buffer); |
5739 | if (!reader) | |
554f786e | 5740 | goto out_unlock; |
8789a9e7 | 5741 | |
ef7a4a16 SR |
5742 | event = rb_reader_event(cpu_buffer); |
5743 | ||
5744 | read = reader->read; | |
fe832be0 | 5745 | commit = rb_page_size(reader); |
667d2412 | 5746 | |
66a8cb95 | 5747 | /* Check if any events were dropped */ |
ff0ff84a | 5748 | missed_events = cpu_buffer->lost_events; |
66a8cb95 | 5749 | |
8789a9e7 | 5750 | /* |
474d32b6 SR |
5751 | * If this page has been partially read or |
5752 | * if len is not big enough to read the rest of the page or | |
5753 | * a writer is still on the page, then | |
5754 | * we must copy the data from the page to the buffer. | |
5755 | * Otherwise, we can simply swap the page with the one passed in. | |
8789a9e7 | 5756 | */ |
474d32b6 | 5757 | if (read || (len < (commit - read)) || |
117c3920 VD |
5758 | cpu_buffer->reader_page == cpu_buffer->commit_page || |
5759 | cpu_buffer->mapped) { | |
667d2412 | 5760 | struct buffer_data_page *rpage = cpu_buffer->reader_page->page; |
474d32b6 SR |
5761 | unsigned int rpos = read; |
5762 | unsigned int pos = 0; | |
ef7a4a16 | 5763 | unsigned int size; |
8789a9e7 | 5764 | |
fa8f4a89 SRG |
5765 | /* |
5766 | * If a full page is expected, this can still be returned | |
5767 | * if there's been a previous partial read and the | |
5768 | * rest of the page can be read and the commit page is off | |
5769 | * the reader page. | |
5770 | */ | |
5771 | if (full && | |
5772 | (!read || (len < (commit - read)) || | |
5773 | cpu_buffer->reader_page == cpu_buffer->commit_page)) | |
554f786e | 5774 | goto out_unlock; |
8789a9e7 | 5775 | |
ef7a4a16 SR |
5776 | if (len > (commit - read)) |
5777 | len = (commit - read); | |
5778 | ||
69d1b839 SR |
5779 | /* Always keep the time extend and data together */ |
5780 | size = rb_event_ts_length(event); | |
ef7a4a16 SR |
5781 | |
5782 | if (len < size) | |
554f786e | 5783 | goto out_unlock; |
ef7a4a16 | 5784 | |
4f3640f8 SR |
5785 | /* save the current timestamp, since the user will need it */ |
5786 | save_timestamp = cpu_buffer->read_stamp; | |
5787 | ||
ef7a4a16 SR |
5788 | /* Need to copy one event at a time */ |
5789 | do { | |
e1e35927 DS |
5790 | /* We need the size of one event, because |
5791 | * rb_advance_reader only advances by one event, | |
5792 | * whereas rb_event_ts_length may include the size of | |
5793 | * one or two events. | |
5794 | * We have already ensured there's enough space if this | |
5795 | * is a time extend. */ | |
5796 | size = rb_event_length(event); | |
474d32b6 | 5797 | memcpy(bpage->data + pos, rpage->data + rpos, size); |
ef7a4a16 SR |
5798 | |
5799 | len -= size; | |
5800 | ||
5801 | rb_advance_reader(cpu_buffer); | |
474d32b6 SR |
5802 | rpos = reader->read; |
5803 | pos += size; | |
ef7a4a16 | 5804 | |
18fab912 HY |
5805 | if (rpos >= commit) |
5806 | break; | |
5807 | ||
ef7a4a16 | 5808 | event = rb_reader_event(cpu_buffer); |
69d1b839 SR |
5809 | /* Always keep the time extend and data together */ |
5810 | size = rb_event_ts_length(event); | |
e1e35927 | 5811 | } while (len >= size); |
667d2412 LJ |
5812 | |
5813 | /* update bpage */ | |
ef7a4a16 | 5814 | local_set(&bpage->commit, pos); |
4f3640f8 | 5815 | bpage->time_stamp = save_timestamp; |
ef7a4a16 | 5816 | |
474d32b6 SR |
5817 | /* we copied everything to the beginning */ |
5818 | read = 0; | |
8789a9e7 | 5819 | } else { |
afbab76a | 5820 | /* update the entry counter */ |
77ae365e | 5821 | cpu_buffer->read += rb_page_entries(reader); |
fe832be0 | 5822 | cpu_buffer->read_bytes += rb_page_size(reader); |
afbab76a | 5823 | |
8789a9e7 | 5824 | /* swap the pages */ |
044fa782 | 5825 | rb_init_page(bpage); |
ef7a4a16 | 5826 | bpage = reader->page; |
bce761d7 | 5827 | reader->page = data_page->data; |
ef7a4a16 | 5828 | local_set(&reader->write, 0); |
778c55d4 | 5829 | local_set(&reader->entries, 0); |
ef7a4a16 | 5830 | reader->read = 0; |
bce761d7 | 5831 | data_page->data = bpage; |
ff0ff84a SR |
5832 | |
5833 | /* | |
5834 | * Use the real_end for the data size, | |
5835 | * This gives us a chance to store the lost events | |
5836 | * on the page. | |
5837 | */ | |
5838 | if (reader->real_end) | |
5839 | local_set(&bpage->commit, reader->real_end); | |
8789a9e7 | 5840 | } |
667d2412 | 5841 | ret = read; |
8789a9e7 | 5842 | |
66a8cb95 | 5843 | cpu_buffer->lost_events = 0; |
2711ca23 SR |
5844 | |
5845 | commit = local_read(&bpage->commit); | |
66a8cb95 SR |
5846 | /* |
5847 | * Set a flag in the commit field if we lost events | |
5848 | */ | |
ff0ff84a | 5849 | if (missed_events) { |
ff0ff84a SR |
5850 | /* If there is room at the end of the page to save the |
5851 | * missed events, then record it there. | |
5852 | */ | |
139f8400 | 5853 | if (buffer->subbuf_size - commit >= sizeof(missed_events)) { |
ff0ff84a SR |
5854 | memcpy(&bpage->data[commit], &missed_events, |
5855 | sizeof(missed_events)); | |
5856 | local_add(RB_MISSED_STORED, &bpage->commit); | |
2711ca23 | 5857 | commit += sizeof(missed_events); |
ff0ff84a | 5858 | } |
66a8cb95 | 5859 | local_add(RB_MISSED_EVENTS, &bpage->commit); |
ff0ff84a | 5860 | } |
66a8cb95 | 5861 | |
2711ca23 SR |
5862 | /* |
5863 | * This page may be off to user land. Zero it out here. | |
5864 | */ | |
139f8400 TSV |
5865 | if (commit < buffer->subbuf_size) |
5866 | memset(&bpage->data[commit], 0, buffer->subbuf_size - commit); | |
2711ca23 | 5867 | |
554f786e | 5868 | out_unlock: |
5389f6fa | 5869 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); |
8789a9e7 | 5870 | |
554f786e | 5871 | out: |
8789a9e7 SR |
5872 | return ret; |
5873 | } | |
d6ce96da | 5874 | EXPORT_SYMBOL_GPL(ring_buffer_read_page); |
8789a9e7 | 5875 | |
bce761d7 TSV |
5876 | /** |
5877 | * ring_buffer_read_page_data - get pointer to the data in the page. | |
5878 | * @page: the page to get the data from | |
5879 | * | |
5880 | * Returns pointer to the actual data in this page. | |
5881 | */ | |
5882 | void *ring_buffer_read_page_data(struct buffer_data_read_page *page) | |
5883 | { | |
5884 | return page->data; | |
5885 | } | |
5886 | EXPORT_SYMBOL_GPL(ring_buffer_read_page_data); | |
5887 | ||
2808e31e TSV |
5888 | /** |
5889 | * ring_buffer_subbuf_size_get - get size of the sub buffer. | |
5890 | * @buffer: the buffer to get the sub buffer size from | |
5891 | * | |
5892 | * Returns size of the sub buffer, in bytes. | |
5893 | */ | |
5894 | int ring_buffer_subbuf_size_get(struct trace_buffer *buffer) | |
5895 | { | |
5896 | return buffer->subbuf_size + BUF_PAGE_HDR_SIZE; | |
5897 | } | |
5898 | EXPORT_SYMBOL_GPL(ring_buffer_subbuf_size_get); | |
5899 | ||
5900 | /** | |
5901 | * ring_buffer_subbuf_order_get - get order of system sub pages in one buffer page. | |
5902 | * @buffer: The ring_buffer to get the system sub page order from | |
5903 | * | |
5904 | * By default, one ring buffer sub page equals to one system page. This parameter | |
5905 | * is configurable, per ring buffer. The size of the ring buffer sub page can be | |
5906 | * extended, but must be an order of system page size. | |
5907 | * | |
5908 | * Returns the order of buffer sub page size, in system pages: | |
5909 | * 0 means the sub buffer size is 1 system page and so forth. | |
5910 | * In case of an error < 0 is returned. | |
5911 | */ | |
5912 | int ring_buffer_subbuf_order_get(struct trace_buffer *buffer) | |
5913 | { | |
5914 | if (!buffer) | |
5915 | return -EINVAL; | |
5916 | ||
5917 | return buffer->subbuf_order; | |
5918 | } | |
5919 | EXPORT_SYMBOL_GPL(ring_buffer_subbuf_order_get); | |
5920 | ||
5921 | /** | |
5922 | * ring_buffer_subbuf_order_set - set the size of ring buffer sub page. | |
5923 | * @buffer: The ring_buffer to set the new page size. | |
5924 | * @order: Order of the system pages in one sub buffer page | |
5925 | * | |
5926 | * By default, one ring buffer pages equals to one system page. This API can be | |
5927 | * used to set new size of the ring buffer page. The size must be order of | |
5928 | * system page size, that's why the input parameter @order is the order of | |
5929 | * system pages that are allocated for one ring buffer page: | |
5930 | * 0 - 1 system page | |
5931 | * 1 - 2 system pages | |
5932 | * 3 - 4 system pages | |
5933 | * ... | |
5934 | * | |
5935 | * Returns 0 on success or < 0 in case of an error. | |
5936 | */ | |
5937 | int ring_buffer_subbuf_order_set(struct trace_buffer *buffer, int order) | |
5938 | { | |
8e7b58c2 SRG |
5939 | struct ring_buffer_per_cpu *cpu_buffer; |
5940 | struct buffer_page *bpage, *tmp; | |
f9b94daa TSV |
5941 | int old_order, old_size; |
5942 | int nr_pages; | |
2808e31e | 5943 | int psize; |
f9b94daa TSV |
5944 | int err; |
5945 | int cpu; | |
2808e31e TSV |
5946 | |
5947 | if (!buffer || order < 0) | |
5948 | return -EINVAL; | |
5949 | ||
5950 | if (buffer->subbuf_order == order) | |
5951 | return 0; | |
5952 | ||
5953 | psize = (1 << order) * PAGE_SIZE; | |
5954 | if (psize <= BUF_PAGE_HDR_SIZE) | |
5955 | return -EINVAL; | |
5956 | ||
e78fb4ea SRG |
5957 | /* Size of a subbuf cannot be greater than the write counter */ |
5958 | if (psize > RB_WRITE_MASK + 1) | |
5959 | return -EINVAL; | |
5960 | ||
f9b94daa TSV |
5961 | old_order = buffer->subbuf_order; |
5962 | old_size = buffer->subbuf_size; | |
5963 | ||
5964 | /* prevent another thread from changing buffer sizes */ | |
5965 | mutex_lock(&buffer->mutex); | |
5966 | atomic_inc(&buffer->record_disabled); | |
5967 | ||
5968 | /* Make sure all commits have finished */ | |
5969 | synchronize_rcu(); | |
5970 | ||
2808e31e TSV |
5971 | buffer->subbuf_order = order; |
5972 | buffer->subbuf_size = psize - BUF_PAGE_HDR_SIZE; | |
5973 | ||
f9b94daa TSV |
5974 | /* Make sure all new buffers are allocated, before deleting the old ones */ |
5975 | for_each_buffer_cpu(buffer, cpu) { | |
8e7b58c2 | 5976 | |
f9b94daa TSV |
5977 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
5978 | continue; | |
5979 | ||
8e7b58c2 SRG |
5980 | cpu_buffer = buffer->buffers[cpu]; |
5981 | ||
117c3920 VD |
5982 | if (cpu_buffer->mapped) { |
5983 | err = -EBUSY; | |
5984 | goto error; | |
5985 | } | |
5986 | ||
353cc219 SRG |
5987 | /* Update the number of pages to match the new size */ |
5988 | nr_pages = old_size * buffer->buffers[cpu]->nr_pages; | |
5989 | nr_pages = DIV_ROUND_UP(nr_pages, buffer->subbuf_size); | |
5990 | ||
8e7b58c2 SRG |
5991 | /* we need a minimum of two pages */ |
5992 | if (nr_pages < 2) | |
5993 | nr_pages = 2; | |
5994 | ||
5995 | cpu_buffer->nr_pages_to_update = nr_pages; | |
5996 | ||
5997 | /* Include the reader page */ | |
5998 | nr_pages++; | |
5999 | ||
6000 | /* Allocate the new size buffer */ | |
6001 | INIT_LIST_HEAD(&cpu_buffer->new_pages); | |
6002 | if (__rb_allocate_pages(cpu_buffer, nr_pages, | |
6003 | &cpu_buffer->new_pages)) { | |
6004 | /* not enough memory for new pages */ | |
f9b94daa TSV |
6005 | err = -ENOMEM; |
6006 | goto error; | |
6007 | } | |
6008 | } | |
6009 | ||
6010 | for_each_buffer_cpu(buffer, cpu) { | |
8e7b58c2 | 6011 | |
f9b94daa TSV |
6012 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) |
6013 | continue; | |
6014 | ||
8e7b58c2 SRG |
6015 | cpu_buffer = buffer->buffers[cpu]; |
6016 | ||
6017 | /* Clear the head bit to make the link list normal to read */ | |
6018 | rb_head_page_deactivate(cpu_buffer); | |
6019 | ||
6020 | /* Now walk the list and free all the old sub buffers */ | |
6021 | list_for_each_entry_safe(bpage, tmp, cpu_buffer->pages, list) { | |
6022 | list_del_init(&bpage->list); | |
6023 | free_buffer_page(bpage); | |
6024 | } | |
6025 | /* The above loop stopped an the last page needing to be freed */ | |
6026 | bpage = list_entry(cpu_buffer->pages, struct buffer_page, list); | |
6027 | free_buffer_page(bpage); | |
6028 | ||
6029 | /* Free the current reader page */ | |
6030 | free_buffer_page(cpu_buffer->reader_page); | |
6031 | ||
6032 | /* One page was allocated for the reader page */ | |
6033 | cpu_buffer->reader_page = list_entry(cpu_buffer->new_pages.next, | |
6034 | struct buffer_page, list); | |
6035 | list_del_init(&cpu_buffer->reader_page->list); | |
6036 | ||
6037 | /* The cpu_buffer pages are a link list with no head */ | |
6038 | cpu_buffer->pages = cpu_buffer->new_pages.next; | |
6039 | cpu_buffer->new_pages.next->prev = cpu_buffer->new_pages.prev; | |
6040 | cpu_buffer->new_pages.prev->next = cpu_buffer->new_pages.next; | |
6041 | ||
6042 | /* Clear the new_pages list */ | |
6043 | INIT_LIST_HEAD(&cpu_buffer->new_pages); | |
6044 | ||
6045 | cpu_buffer->head_page | |
6046 | = list_entry(cpu_buffer->pages, struct buffer_page, list); | |
6047 | cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; | |
6048 | ||
6049 | cpu_buffer->nr_pages = cpu_buffer->nr_pages_to_update; | |
6050 | cpu_buffer->nr_pages_to_update = 0; | |
6051 | ||
6052 | free_pages((unsigned long)cpu_buffer->free_page, old_order); | |
6053 | cpu_buffer->free_page = NULL; | |
6054 | ||
6055 | rb_head_page_activate(cpu_buffer); | |
6056 | ||
6057 | rb_check_pages(cpu_buffer); | |
f9b94daa TSV |
6058 | } |
6059 | ||
6060 | atomic_dec(&buffer->record_disabled); | |
6061 | mutex_unlock(&buffer->mutex); | |
6062 | ||
2808e31e | 6063 | return 0; |
f9b94daa TSV |
6064 | |
6065 | error: | |
6066 | buffer->subbuf_order = old_order; | |
6067 | buffer->subbuf_size = old_size; | |
6068 | ||
6069 | atomic_dec(&buffer->record_disabled); | |
6070 | mutex_unlock(&buffer->mutex); | |
6071 | ||
6072 | for_each_buffer_cpu(buffer, cpu) { | |
8e7b58c2 SRG |
6073 | cpu_buffer = buffer->buffers[cpu]; |
6074 | ||
6075 | if (!cpu_buffer->nr_pages_to_update) | |
f9b94daa | 6076 | continue; |
8e7b58c2 SRG |
6077 | |
6078 | list_for_each_entry_safe(bpage, tmp, &cpu_buffer->new_pages, list) { | |
6079 | list_del_init(&bpage->list); | |
6080 | free_buffer_page(bpage); | |
6081 | } | |
f9b94daa | 6082 | } |
f9b94daa TSV |
6083 | |
6084 | return err; | |
2808e31e TSV |
6085 | } |
6086 | EXPORT_SYMBOL_GPL(ring_buffer_subbuf_order_set); | |
6087 | ||
117c3920 VD |
6088 | static int rb_alloc_meta_page(struct ring_buffer_per_cpu *cpu_buffer) |
6089 | { | |
6090 | struct page *page; | |
6091 | ||
6092 | if (cpu_buffer->meta_page) | |
6093 | return 0; | |
6094 | ||
6095 | page = alloc_page(GFP_USER | __GFP_ZERO); | |
6096 | if (!page) | |
6097 | return -ENOMEM; | |
6098 | ||
6099 | cpu_buffer->meta_page = page_to_virt(page); | |
6100 | ||
6101 | return 0; | |
6102 | } | |
6103 | ||
6104 | static void rb_free_meta_page(struct ring_buffer_per_cpu *cpu_buffer) | |
6105 | { | |
6106 | unsigned long addr = (unsigned long)cpu_buffer->meta_page; | |
6107 | ||
6108 | free_page(addr); | |
6109 | cpu_buffer->meta_page = NULL; | |
6110 | } | |
6111 | ||
6112 | static void rb_setup_ids_meta_page(struct ring_buffer_per_cpu *cpu_buffer, | |
6113 | unsigned long *subbuf_ids) | |
6114 | { | |
6115 | struct trace_buffer_meta *meta = cpu_buffer->meta_page; | |
6116 | unsigned int nr_subbufs = cpu_buffer->nr_pages + 1; | |
6117 | struct buffer_page *first_subbuf, *subbuf; | |
6118 | int id = 0; | |
6119 | ||
6120 | subbuf_ids[id] = (unsigned long)cpu_buffer->reader_page->page; | |
6121 | cpu_buffer->reader_page->id = id++; | |
6122 | ||
6123 | first_subbuf = subbuf = rb_set_head_page(cpu_buffer); | |
6124 | do { | |
6125 | if (WARN_ON(id >= nr_subbufs)) | |
6126 | break; | |
6127 | ||
6128 | subbuf_ids[id] = (unsigned long)subbuf->page; | |
6129 | subbuf->id = id; | |
6130 | ||
6131 | rb_inc_page(&subbuf); | |
6132 | id++; | |
6133 | } while (subbuf != first_subbuf); | |
6134 | ||
6135 | /* install subbuf ID to kern VA translation */ | |
6136 | cpu_buffer->subbuf_ids = subbuf_ids; | |
6137 | ||
6138 | meta->meta_page_size = PAGE_SIZE; | |
6139 | meta->meta_struct_len = sizeof(*meta); | |
6140 | meta->nr_subbufs = nr_subbufs; | |
6141 | meta->subbuf_size = cpu_buffer->buffer->subbuf_size + BUF_PAGE_HDR_SIZE; | |
6142 | ||
6143 | rb_update_meta_page(cpu_buffer); | |
6144 | } | |
6145 | ||
6146 | static struct ring_buffer_per_cpu * | |
6147 | rb_get_mapped_buffer(struct trace_buffer *buffer, int cpu) | |
6148 | { | |
6149 | struct ring_buffer_per_cpu *cpu_buffer; | |
6150 | ||
6151 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
6152 | return ERR_PTR(-EINVAL); | |
6153 | ||
6154 | cpu_buffer = buffer->buffers[cpu]; | |
6155 | ||
6156 | mutex_lock(&cpu_buffer->mapping_lock); | |
6157 | ||
6158 | if (!cpu_buffer->mapped) { | |
6159 | mutex_unlock(&cpu_buffer->mapping_lock); | |
6160 | return ERR_PTR(-ENODEV); | |
6161 | } | |
6162 | ||
6163 | return cpu_buffer; | |
6164 | } | |
6165 | ||
6166 | static void rb_put_mapped_buffer(struct ring_buffer_per_cpu *cpu_buffer) | |
6167 | { | |
6168 | mutex_unlock(&cpu_buffer->mapping_lock); | |
6169 | } | |
6170 | ||
6171 | /* | |
6172 | * Fast-path for rb_buffer_(un)map(). Called whenever the meta-page doesn't need | |
6173 | * to be set-up or torn-down. | |
6174 | */ | |
6175 | static int __rb_inc_dec_mapped(struct ring_buffer_per_cpu *cpu_buffer, | |
6176 | bool inc) | |
6177 | { | |
6178 | unsigned long flags; | |
6179 | ||
6180 | lockdep_assert_held(&cpu_buffer->mapping_lock); | |
6181 | ||
6182 | if (inc && cpu_buffer->mapped == UINT_MAX) | |
6183 | return -EBUSY; | |
6184 | ||
6185 | if (WARN_ON(!inc && cpu_buffer->mapped == 0)) | |
6186 | return -EINVAL; | |
6187 | ||
6188 | mutex_lock(&cpu_buffer->buffer->mutex); | |
6189 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
6190 | ||
6191 | if (inc) | |
6192 | cpu_buffer->mapped++; | |
6193 | else | |
6194 | cpu_buffer->mapped--; | |
6195 | ||
6196 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
6197 | mutex_unlock(&cpu_buffer->buffer->mutex); | |
6198 | ||
6199 | return 0; | |
6200 | } | |
6201 | ||
6202 | /* | |
6203 | * +--------------+ pgoff == 0 | |
6204 | * | meta page | | |
6205 | * +--------------+ pgoff == 1 | |
6206 | * | subbuffer 0 | | |
6207 | * | | | |
6208 | * +--------------+ pgoff == (1 + (1 << subbuf_order)) | |
6209 | * | subbuffer 1 | | |
6210 | * | | | |
6211 | * ... | |
6212 | */ | |
6213 | #ifdef CONFIG_MMU | |
6214 | static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer, | |
6215 | struct vm_area_struct *vma) | |
6216 | { | |
6217 | unsigned long nr_subbufs, nr_pages, vma_pages, pgoff = vma->vm_pgoff; | |
6218 | unsigned int subbuf_pages, subbuf_order; | |
6219 | struct page **pages; | |
6220 | int p = 0, s = 0; | |
6221 | int err; | |
6222 | ||
6223 | /* Refuse MP_PRIVATE or writable mappings */ | |
6224 | if (vma->vm_flags & VM_WRITE || vma->vm_flags & VM_EXEC || | |
6225 | !(vma->vm_flags & VM_MAYSHARE)) | |
6226 | return -EPERM; | |
6227 | ||
6228 | /* | |
6229 | * Make sure the mapping cannot become writable later. Also tell the VM | |
6230 | * to not touch these pages (VM_DONTCOPY | VM_DONTEXPAND). | |
6231 | */ | |
6232 | vm_flags_mod(vma, VM_DONTCOPY | VM_DONTEXPAND | VM_DONTDUMP, | |
6233 | VM_MAYWRITE); | |
6234 | ||
6235 | lockdep_assert_held(&cpu_buffer->mapping_lock); | |
6236 | ||
6237 | subbuf_order = cpu_buffer->buffer->subbuf_order; | |
6238 | subbuf_pages = 1 << subbuf_order; | |
6239 | ||
6240 | nr_subbufs = cpu_buffer->nr_pages + 1; /* + reader-subbuf */ | |
6241 | nr_pages = ((nr_subbufs) << subbuf_order) - pgoff + 1; /* + meta-page */ | |
6242 | ||
6243 | vma_pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; | |
6244 | if (!vma_pages || vma_pages > nr_pages) | |
6245 | return -EINVAL; | |
6246 | ||
6247 | nr_pages = vma_pages; | |
6248 | ||
6249 | pages = kcalloc(nr_pages, sizeof(*pages), GFP_KERNEL); | |
6250 | if (!pages) | |
6251 | return -ENOMEM; | |
6252 | ||
6253 | if (!pgoff) { | |
6254 | pages[p++] = virt_to_page(cpu_buffer->meta_page); | |
6255 | ||
6256 | /* | |
6257 | * TODO: Align sub-buffers on their size, once | |
6258 | * vm_insert_pages() supports the zero-page. | |
6259 | */ | |
6260 | } else { | |
6261 | /* Skip the meta-page */ | |
6262 | pgoff--; | |
6263 | ||
6264 | if (pgoff % subbuf_pages) { | |
6265 | err = -EINVAL; | |
6266 | goto out; | |
6267 | } | |
6268 | ||
6269 | s += pgoff / subbuf_pages; | |
6270 | } | |
6271 | ||
6272 | while (p < nr_pages) { | |
b9c6820f | 6273 | struct page *page = virt_to_page((void *)cpu_buffer->subbuf_ids[s]); |
117c3920 VD |
6274 | int off = 0; |
6275 | ||
6276 | if (WARN_ON_ONCE(s >= nr_subbufs)) { | |
6277 | err = -EINVAL; | |
6278 | goto out; | |
6279 | } | |
6280 | ||
6281 | for (; off < (1 << (subbuf_order)); off++, page++) { | |
6282 | if (p >= nr_pages) | |
6283 | break; | |
6284 | ||
6285 | pages[p++] = page; | |
6286 | } | |
6287 | s++; | |
6288 | } | |
6289 | ||
6290 | err = vm_insert_pages(vma, vma->vm_start, pages, &nr_pages); | |
6291 | ||
6292 | out: | |
6293 | kfree(pages); | |
6294 | ||
6295 | return err; | |
6296 | } | |
6297 | #else | |
6298 | static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer, | |
6299 | struct vm_area_struct *vma) | |
6300 | { | |
6301 | return -EOPNOTSUPP; | |
6302 | } | |
6303 | #endif | |
6304 | ||
6305 | int ring_buffer_map(struct trace_buffer *buffer, int cpu, | |
6306 | struct vm_area_struct *vma) | |
6307 | { | |
6308 | struct ring_buffer_per_cpu *cpu_buffer; | |
6309 | unsigned long flags, *subbuf_ids; | |
6310 | int err = 0; | |
6311 | ||
6312 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
6313 | return -EINVAL; | |
6314 | ||
6315 | cpu_buffer = buffer->buffers[cpu]; | |
6316 | ||
6317 | mutex_lock(&cpu_buffer->mapping_lock); | |
6318 | ||
6319 | if (cpu_buffer->mapped) { | |
6320 | err = __rb_map_vma(cpu_buffer, vma); | |
6321 | if (!err) | |
6322 | err = __rb_inc_dec_mapped(cpu_buffer, true); | |
6323 | mutex_unlock(&cpu_buffer->mapping_lock); | |
6324 | return err; | |
6325 | } | |
6326 | ||
6327 | /* prevent another thread from changing buffer/sub-buffer sizes */ | |
6328 | mutex_lock(&buffer->mutex); | |
6329 | ||
6330 | err = rb_alloc_meta_page(cpu_buffer); | |
6331 | if (err) | |
6332 | goto unlock; | |
6333 | ||
6334 | /* subbuf_ids include the reader while nr_pages does not */ | |
6335 | subbuf_ids = kcalloc(cpu_buffer->nr_pages + 1, sizeof(*subbuf_ids), GFP_KERNEL); | |
6336 | if (!subbuf_ids) { | |
6337 | rb_free_meta_page(cpu_buffer); | |
6338 | err = -ENOMEM; | |
6339 | goto unlock; | |
6340 | } | |
6341 | ||
6342 | atomic_inc(&cpu_buffer->resize_disabled); | |
6343 | ||
6344 | /* | |
6345 | * Lock all readers to block any subbuf swap until the subbuf IDs are | |
6346 | * assigned. | |
6347 | */ | |
6348 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
6349 | rb_setup_ids_meta_page(cpu_buffer, subbuf_ids); | |
6350 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
6351 | ||
6352 | err = __rb_map_vma(cpu_buffer, vma); | |
6353 | if (!err) { | |
6354 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
6355 | cpu_buffer->mapped = 1; | |
6356 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
6357 | } else { | |
6358 | kfree(cpu_buffer->subbuf_ids); | |
6359 | cpu_buffer->subbuf_ids = NULL; | |
6360 | rb_free_meta_page(cpu_buffer); | |
6361 | } | |
6362 | ||
6363 | unlock: | |
6364 | mutex_unlock(&buffer->mutex); | |
6365 | mutex_unlock(&cpu_buffer->mapping_lock); | |
6366 | ||
6367 | return err; | |
6368 | } | |
6369 | ||
6370 | int ring_buffer_unmap(struct trace_buffer *buffer, int cpu) | |
6371 | { | |
6372 | struct ring_buffer_per_cpu *cpu_buffer; | |
6373 | unsigned long flags; | |
6374 | int err = 0; | |
6375 | ||
6376 | if (!cpumask_test_cpu(cpu, buffer->cpumask)) | |
6377 | return -EINVAL; | |
6378 | ||
6379 | cpu_buffer = buffer->buffers[cpu]; | |
6380 | ||
6381 | mutex_lock(&cpu_buffer->mapping_lock); | |
6382 | ||
6383 | if (!cpu_buffer->mapped) { | |
6384 | err = -ENODEV; | |
6385 | goto out; | |
6386 | } else if (cpu_buffer->mapped > 1) { | |
6387 | __rb_inc_dec_mapped(cpu_buffer, false); | |
6388 | goto out; | |
6389 | } | |
6390 | ||
6391 | mutex_lock(&buffer->mutex); | |
6392 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
6393 | ||
6394 | cpu_buffer->mapped = 0; | |
6395 | ||
6396 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
6397 | ||
6398 | kfree(cpu_buffer->subbuf_ids); | |
6399 | cpu_buffer->subbuf_ids = NULL; | |
6400 | rb_free_meta_page(cpu_buffer); | |
6401 | atomic_dec(&cpu_buffer->resize_disabled); | |
6402 | ||
6403 | mutex_unlock(&buffer->mutex); | |
6404 | ||
6405 | out: | |
6406 | mutex_unlock(&cpu_buffer->mapping_lock); | |
6407 | ||
6408 | return err; | |
6409 | } | |
6410 | ||
6411 | int ring_buffer_map_get_reader(struct trace_buffer *buffer, int cpu) | |
6412 | { | |
6413 | struct ring_buffer_per_cpu *cpu_buffer; | |
fe832be0 SRG |
6414 | struct buffer_page *reader; |
6415 | unsigned long missed_events; | |
117c3920 VD |
6416 | unsigned long reader_size; |
6417 | unsigned long flags; | |
6418 | ||
6419 | cpu_buffer = rb_get_mapped_buffer(buffer, cpu); | |
6420 | if (IS_ERR(cpu_buffer)) | |
6421 | return (int)PTR_ERR(cpu_buffer); | |
6422 | ||
6423 | raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); | |
6424 | ||
6425 | consume: | |
6426 | if (rb_per_cpu_empty(cpu_buffer)) | |
6427 | goto out; | |
6428 | ||
6429 | reader_size = rb_page_size(cpu_buffer->reader_page); | |
6430 | ||
6431 | /* | |
6432 | * There are data to be read on the current reader page, we can | |
6433 | * return to the caller. But before that, we assume the latter will read | |
6434 | * everything. Let's update the kernel reader accordingly. | |
6435 | */ | |
6436 | if (cpu_buffer->reader_page->read < reader_size) { | |
6437 | while (cpu_buffer->reader_page->read < reader_size) | |
6438 | rb_advance_reader(cpu_buffer); | |
6439 | goto out; | |
6440 | } | |
6441 | ||
fe832be0 SRG |
6442 | reader = rb_get_reader_page(cpu_buffer); |
6443 | if (WARN_ON(!reader)) | |
117c3920 VD |
6444 | goto out; |
6445 | ||
fe832be0 SRG |
6446 | /* Check if any events were dropped */ |
6447 | missed_events = cpu_buffer->lost_events; | |
6448 | ||
6449 | if (cpu_buffer->reader_page != cpu_buffer->commit_page) { | |
6450 | if (missed_events) { | |
6451 | struct buffer_data_page *bpage = reader->page; | |
6452 | unsigned int commit; | |
6453 | /* | |
6454 | * Use the real_end for the data size, | |
6455 | * This gives us a chance to store the lost events | |
6456 | * on the page. | |
6457 | */ | |
6458 | if (reader->real_end) | |
6459 | local_set(&bpage->commit, reader->real_end); | |
6460 | /* | |
6461 | * If there is room at the end of the page to save the | |
6462 | * missed events, then record it there. | |
6463 | */ | |
6464 | commit = rb_page_size(reader); | |
6465 | if (buffer->subbuf_size - commit >= sizeof(missed_events)) { | |
6466 | memcpy(&bpage->data[commit], &missed_events, | |
6467 | sizeof(missed_events)); | |
6468 | local_add(RB_MISSED_STORED, &bpage->commit); | |
6469 | } | |
6470 | local_add(RB_MISSED_EVENTS, &bpage->commit); | |
6471 | } | |
6472 | } else { | |
6473 | /* | |
6474 | * There really shouldn't be any missed events if the commit | |
6475 | * is on the reader page. | |
6476 | */ | |
6477 | WARN_ON_ONCE(missed_events); | |
6478 | } | |
6479 | ||
6480 | cpu_buffer->lost_events = 0; | |
6481 | ||
117c3920 VD |
6482 | goto consume; |
6483 | ||
6484 | out: | |
6485 | /* Some archs do not have data cache coherency between kernel and user-space */ | |
6486 | flush_dcache_folio(virt_to_folio(cpu_buffer->reader_page->page)); | |
6487 | ||
6488 | rb_update_meta_page(cpu_buffer); | |
6489 | ||
6490 | raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); | |
6491 | rb_put_mapped_buffer(cpu_buffer); | |
6492 | ||
6493 | return 0; | |
6494 | } | |
6495 | ||
b32614c0 SAS |
6496 | /* |
6497 | * We only allocate new buffers, never free them if the CPU goes down. | |
6498 | * If we were to free the buffer, then the user would lose any trace that was in | |
6499 | * the buffer. | |
6500 | */ | |
6501 | int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node) | |
554f786e | 6502 | { |
13292494 | 6503 | struct trace_buffer *buffer; |
9b94a8fb SRRH |
6504 | long nr_pages_same; |
6505 | int cpu_i; | |
6506 | unsigned long nr_pages; | |
554f786e | 6507 | |
13292494 | 6508 | buffer = container_of(node, struct trace_buffer, node); |
b32614c0 SAS |
6509 | if (cpumask_test_cpu(cpu, buffer->cpumask)) |
6510 | return 0; | |
6511 | ||
6512 | nr_pages = 0; | |
6513 | nr_pages_same = 1; | |
6514 | /* check if all cpu sizes are same */ | |
6515 | for_each_buffer_cpu(buffer, cpu_i) { | |
6516 | /* fill in the size from first enabled cpu */ | |
6517 | if (nr_pages == 0) | |
6518 | nr_pages = buffer->buffers[cpu_i]->nr_pages; | |
6519 | if (nr_pages != buffer->buffers[cpu_i]->nr_pages) { | |
6520 | nr_pages_same = 0; | |
6521 | break; | |
554f786e | 6522 | } |
554f786e | 6523 | } |
b32614c0 SAS |
6524 | /* allocate minimum pages, user can later expand it */ |
6525 | if (!nr_pages_same) | |
6526 | nr_pages = 2; | |
6527 | buffer->buffers[cpu] = | |
6528 | rb_allocate_cpu_buffer(buffer, nr_pages, cpu); | |
6529 | if (!buffer->buffers[cpu]) { | |
6530 | WARN(1, "failed to allocate ring buffer on CPU %u\n", | |
6531 | cpu); | |
6532 | return -ENOMEM; | |
6533 | } | |
6534 | smp_wmb(); | |
6535 | cpumask_set_cpu(cpu, buffer->cpumask); | |
6536 | return 0; | |
554f786e | 6537 | } |
6c43e554 SRRH |
6538 | |
6539 | #ifdef CONFIG_RING_BUFFER_STARTUP_TEST | |
6540 | /* | |
6541 | * This is a basic integrity check of the ring buffer. | |
6542 | * Late in the boot cycle this test will run when configured in. | |
6543 | * It will kick off a thread per CPU that will go into a loop | |
6544 | * writing to the per cpu ring buffer various sizes of data. | |
6545 | * Some of the data will be large items, some small. | |
6546 | * | |
6547 | * Another thread is created that goes into a spin, sending out | |
6548 | * IPIs to the other CPUs to also write into the ring buffer. | |
6549 | * this is to test the nesting ability of the buffer. | |
6550 | * | |
6551 | * Basic stats are recorded and reported. If something in the | |
6552 | * ring buffer should happen that's not expected, a big warning | |
6553 | * is displayed and all ring buffers are disabled. | |
6554 | */ | |
6555 | static struct task_struct *rb_threads[NR_CPUS] __initdata; | |
6556 | ||
6557 | struct rb_test_data { | |
13292494 | 6558 | struct trace_buffer *buffer; |
6c43e554 SRRH |
6559 | unsigned long events; |
6560 | unsigned long bytes_written; | |
6561 | unsigned long bytes_alloc; | |
6562 | unsigned long bytes_dropped; | |
6563 | unsigned long events_nested; | |
6564 | unsigned long bytes_written_nested; | |
6565 | unsigned long bytes_alloc_nested; | |
6566 | unsigned long bytes_dropped_nested; | |
6567 | int min_size_nested; | |
6568 | int max_size_nested; | |
6569 | int max_size; | |
6570 | int min_size; | |
6571 | int cpu; | |
6572 | int cnt; | |
6573 | }; | |
6574 | ||
6575 | static struct rb_test_data rb_data[NR_CPUS] __initdata; | |
6576 | ||
6577 | /* 1 meg per cpu */ | |
6578 | #define RB_TEST_BUFFER_SIZE 1048576 | |
6579 | ||
6580 | static char rb_string[] __initdata = | |
6581 | "abcdefghijklmnopqrstuvwxyz1234567890!@#$%^&*()?+\\" | |
6582 | "?+|:';\",.<>/?abcdefghijklmnopqrstuvwxyz1234567890" | |
6583 | "!@#$%^&*()?+\\?+|:';\",.<>/?abcdefghijklmnopqrstuv"; | |
6584 | ||
6585 | static bool rb_test_started __initdata; | |
6586 | ||
6587 | struct rb_item { | |
6588 | int size; | |
6589 | char str[]; | |
6590 | }; | |
6591 | ||
6592 | static __init int rb_write_something(struct rb_test_data *data, bool nested) | |
6593 | { | |
6594 | struct ring_buffer_event *event; | |
6595 | struct rb_item *item; | |
6596 | bool started; | |
6597 | int event_len; | |
6598 | int size; | |
6599 | int len; | |
6600 | int cnt; | |
6601 | ||
6602 | /* Have nested writes different that what is written */ | |
6603 | cnt = data->cnt + (nested ? 27 : 0); | |
6604 | ||
6605 | /* Multiply cnt by ~e, to make some unique increment */ | |
40ed29b3 | 6606 | size = (cnt * 68 / 25) % (sizeof(rb_string) - 1); |
6c43e554 SRRH |
6607 | |
6608 | len = size + sizeof(struct rb_item); | |
6609 | ||
6610 | started = rb_test_started; | |
6611 | /* read rb_test_started before checking buffer enabled */ | |
6612 | smp_rmb(); | |
6613 | ||
6614 | event = ring_buffer_lock_reserve(data->buffer, len); | |
6615 | if (!event) { | |
6616 | /* Ignore dropped events before test starts. */ | |
6617 | if (started) { | |
6618 | if (nested) | |
6619 | data->bytes_dropped += len; | |
6620 | else | |
6621 | data->bytes_dropped_nested += len; | |
6622 | } | |
6623 | return len; | |
6624 | } | |
6625 | ||
6626 | event_len = ring_buffer_event_length(event); | |
6627 | ||
6628 | if (RB_WARN_ON(data->buffer, event_len < len)) | |
6629 | goto out; | |
6630 | ||
6631 | item = ring_buffer_event_data(event); | |
6632 | item->size = size; | |
6633 | memcpy(item->str, rb_string, size); | |
6634 | ||
6635 | if (nested) { | |
6636 | data->bytes_alloc_nested += event_len; | |
6637 | data->bytes_written_nested += len; | |
6638 | data->events_nested++; | |
6639 | if (!data->min_size_nested || len < data->min_size_nested) | |
6640 | data->min_size_nested = len; | |
6641 | if (len > data->max_size_nested) | |
6642 | data->max_size_nested = len; | |
6643 | } else { | |
6644 | data->bytes_alloc += event_len; | |
6645 | data->bytes_written += len; | |
6646 | data->events++; | |
6647 | if (!data->min_size || len < data->min_size) | |
6648 | data->max_size = len; | |
6649 | if (len > data->max_size) | |
6650 | data->max_size = len; | |
6651 | } | |
6652 | ||
6653 | out: | |
04aabc32 | 6654 | ring_buffer_unlock_commit(data->buffer); |
6c43e554 SRRH |
6655 | |
6656 | return 0; | |
6657 | } | |
6658 | ||
6659 | static __init int rb_test(void *arg) | |
6660 | { | |
6661 | struct rb_test_data *data = arg; | |
6662 | ||
6663 | while (!kthread_should_stop()) { | |
6664 | rb_write_something(data, false); | |
6665 | data->cnt++; | |
6666 | ||
6667 | set_current_state(TASK_INTERRUPTIBLE); | |
6668 | /* Now sleep between a min of 100-300us and a max of 1ms */ | |
6669 | usleep_range(((data->cnt % 3) + 1) * 100, 1000); | |
6670 | } | |
6671 | ||
6672 | return 0; | |
6673 | } | |
6674 | ||
6675 | static __init void rb_ipi(void *ignore) | |
6676 | { | |
6677 | struct rb_test_data *data; | |
6678 | int cpu = smp_processor_id(); | |
6679 | ||
6680 | data = &rb_data[cpu]; | |
6681 | rb_write_something(data, true); | |
6682 | } | |
6683 | ||
6684 | static __init int rb_hammer_test(void *arg) | |
6685 | { | |
6686 | while (!kthread_should_stop()) { | |
6687 | ||
6688 | /* Send an IPI to all cpus to write data! */ | |
6689 | smp_call_function(rb_ipi, NULL, 1); | |
6690 | /* No sleep, but for non preempt, let others run */ | |
6691 | schedule(); | |
6692 | } | |
6693 | ||
6694 | return 0; | |
6695 | } | |
6696 | ||
6697 | static __init int test_ringbuffer(void) | |
6698 | { | |
6699 | struct task_struct *rb_hammer; | |
13292494 | 6700 | struct trace_buffer *buffer; |
6c43e554 SRRH |
6701 | int cpu; |
6702 | int ret = 0; | |
6703 | ||
a356646a | 6704 | if (security_locked_down(LOCKDOWN_TRACEFS)) { |
ee195452 | 6705 | pr_warn("Lockdown is enabled, skipping ring buffer tests\n"); |
a356646a SRV |
6706 | return 0; |
6707 | } | |
6708 | ||
6c43e554 SRRH |
6709 | pr_info("Running ring buffer tests...\n"); |
6710 | ||
6711 | buffer = ring_buffer_alloc(RB_TEST_BUFFER_SIZE, RB_FL_OVERWRITE); | |
6712 | if (WARN_ON(!buffer)) | |
6713 | return 0; | |
6714 | ||
6715 | /* Disable buffer so that threads can't write to it yet */ | |
6716 | ring_buffer_record_off(buffer); | |
6717 | ||
6718 | for_each_online_cpu(cpu) { | |
6719 | rb_data[cpu].buffer = buffer; | |
6720 | rb_data[cpu].cpu = cpu; | |
6721 | rb_data[cpu].cnt = cpu; | |
64ed3a04 CH |
6722 | rb_threads[cpu] = kthread_run_on_cpu(rb_test, &rb_data[cpu], |
6723 | cpu, "rbtester/%u"); | |
62277de7 | 6724 | if (WARN_ON(IS_ERR(rb_threads[cpu]))) { |
6c43e554 | 6725 | pr_cont("FAILED\n"); |
62277de7 | 6726 | ret = PTR_ERR(rb_threads[cpu]); |
6c43e554 SRRH |
6727 | goto out_free; |
6728 | } | |
6c43e554 SRRH |
6729 | } |
6730 | ||
6731 | /* Now create the rb hammer! */ | |
6732 | rb_hammer = kthread_run(rb_hammer_test, NULL, "rbhammer"); | |
62277de7 | 6733 | if (WARN_ON(IS_ERR(rb_hammer))) { |
6c43e554 | 6734 | pr_cont("FAILED\n"); |
62277de7 | 6735 | ret = PTR_ERR(rb_hammer); |
6c43e554 SRRH |
6736 | goto out_free; |
6737 | } | |
6738 | ||
6739 | ring_buffer_record_on(buffer); | |
6740 | /* | |
6741 | * Show buffer is enabled before setting rb_test_started. | |
6742 | * Yes there's a small race window where events could be | |
6743 | * dropped and the thread wont catch it. But when a ring | |
6744 | * buffer gets enabled, there will always be some kind of | |
6745 | * delay before other CPUs see it. Thus, we don't care about | |
6746 | * those dropped events. We care about events dropped after | |
6747 | * the threads see that the buffer is active. | |
6748 | */ | |
6749 | smp_wmb(); | |
6750 | rb_test_started = true; | |
6751 | ||
6752 | set_current_state(TASK_INTERRUPTIBLE); | |
6753 | /* Just run for 10 seconds */; | |
6754 | schedule_timeout(10 * HZ); | |
6755 | ||
6756 | kthread_stop(rb_hammer); | |
6757 | ||
6758 | out_free: | |
6759 | for_each_online_cpu(cpu) { | |
6760 | if (!rb_threads[cpu]) | |
6761 | break; | |
6762 | kthread_stop(rb_threads[cpu]); | |
6763 | } | |
6764 | if (ret) { | |
6765 | ring_buffer_free(buffer); | |
6766 | return ret; | |
6767 | } | |
6768 | ||
6769 | /* Report! */ | |
6770 | pr_info("finished\n"); | |
6771 | for_each_online_cpu(cpu) { | |
6772 | struct ring_buffer_event *event; | |
6773 | struct rb_test_data *data = &rb_data[cpu]; | |
6774 | struct rb_item *item; | |
6775 | unsigned long total_events; | |
6776 | unsigned long total_dropped; | |
6777 | unsigned long total_written; | |
6778 | unsigned long total_alloc; | |
6779 | unsigned long total_read = 0; | |
6780 | unsigned long total_size = 0; | |
6781 | unsigned long total_len = 0; | |
6782 | unsigned long total_lost = 0; | |
6783 | unsigned long lost; | |
6784 | int big_event_size; | |
6785 | int small_event_size; | |
6786 | ||
6787 | ret = -1; | |
6788 | ||
6789 | total_events = data->events + data->events_nested; | |
6790 | total_written = data->bytes_written + data->bytes_written_nested; | |
6791 | total_alloc = data->bytes_alloc + data->bytes_alloc_nested; | |
6792 | total_dropped = data->bytes_dropped + data->bytes_dropped_nested; | |
6793 | ||
6794 | big_event_size = data->max_size + data->max_size_nested; | |
6795 | small_event_size = data->min_size + data->min_size_nested; | |
6796 | ||
6797 | pr_info("CPU %d:\n", cpu); | |
6798 | pr_info(" events: %ld\n", total_events); | |
6799 | pr_info(" dropped bytes: %ld\n", total_dropped); | |
6800 | pr_info(" alloced bytes: %ld\n", total_alloc); | |
6801 | pr_info(" written bytes: %ld\n", total_written); | |
6802 | pr_info(" biggest event: %d\n", big_event_size); | |
6803 | pr_info(" smallest event: %d\n", small_event_size); | |
6804 | ||
6805 | if (RB_WARN_ON(buffer, total_dropped)) | |
6806 | break; | |
6807 | ||
6808 | ret = 0; | |
6809 | ||
6810 | while ((event = ring_buffer_consume(buffer, cpu, NULL, &lost))) { | |
6811 | total_lost += lost; | |
6812 | item = ring_buffer_event_data(event); | |
6813 | total_len += ring_buffer_event_length(event); | |
6814 | total_size += item->size + sizeof(struct rb_item); | |
6815 | if (memcmp(&item->str[0], rb_string, item->size) != 0) { | |
6816 | pr_info("FAILED!\n"); | |
6817 | pr_info("buffer had: %.*s\n", item->size, item->str); | |
6818 | pr_info("expected: %.*s\n", item->size, rb_string); | |
6819 | RB_WARN_ON(buffer, 1); | |
6820 | ret = -1; | |
6821 | break; | |
6822 | } | |
6823 | total_read++; | |
6824 | } | |
6825 | if (ret) | |
6826 | break; | |
6827 | ||
6828 | ret = -1; | |
6829 | ||
6830 | pr_info(" read events: %ld\n", total_read); | |
6831 | pr_info(" lost events: %ld\n", total_lost); | |
6832 | pr_info(" total events: %ld\n", total_lost + total_read); | |
6833 | pr_info(" recorded len bytes: %ld\n", total_len); | |
6834 | pr_info(" recorded size bytes: %ld\n", total_size); | |
ed888241 | 6835 | if (total_lost) { |
6c43e554 SRRH |
6836 | pr_info(" With dropped events, record len and size may not match\n" |
6837 | " alloced and written from above\n"); | |
ed888241 | 6838 | } else { |
6c43e554 SRRH |
6839 | if (RB_WARN_ON(buffer, total_len != total_alloc || |
6840 | total_size != total_written)) | |
6841 | break; | |
6842 | } | |
6843 | if (RB_WARN_ON(buffer, total_lost + total_read != total_events)) | |
6844 | break; | |
6845 | ||
6846 | ret = 0; | |
6847 | } | |
6848 | if (!ret) | |
6849 | pr_info("Ring buffer PASSED!\n"); | |
6850 | ||
6851 | ring_buffer_free(buffer); | |
6852 | return 0; | |
6853 | } | |
6854 | ||
6855 | late_initcall(test_ringbuffer); | |
6856 | #endif /* CONFIG_RING_BUFFER_STARTUP_TEST */ |