b09f3215 |
1 | |
04180f7f |
2 | /* LTTng user-space "fast" tracing header |
b09f3215 |
3 | * |
4 | * Copyright 2006 Mathieu Desnoyers |
5 | * |
6 | */ |
7 | |
04180f7f |
8 | #ifndef _LTT_USERTRACE_FAST_H |
9 | #define _LTT_USERTRACE_FAST_H |
b09f3215 |
10 | |
8b30e7bc |
11 | #ifdef LTT_TRACE |
12 | |
b09f3215 |
13 | #include <errno.h> |
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14 | #include <asm/atomic.h> |
700d350d |
15 | #include <pthread.h> |
32f2b04a |
16 | #include <stdint.h> |
17 | #include <syscall.h> |
18 | #include <linux/futex.h> |
b5d612cb |
19 | #include <asm/timex.h> |
32f2b04a |
20 | |
8b30e7bc |
21 | #include <ltt/ltt-facility-id-user_generic.h> |
22 | #include <ltt/ltt-generic.h> |
23 | |
32f2b04a |
24 | #ifndef futex |
5ffa9d14 |
25 | static inline __attribute__((no_instrument_function)) |
26 | _syscall6(long, futex, unsigned long, uaddr, int, op, int, val, |
32f2b04a |
27 | unsigned long, timeout, unsigned long, uaddr2, int, val2) |
28 | #endif //futex |
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29 | |
47d7d576 |
30 | |
5ffa9d14 |
31 | |
47d7d576 |
32 | #ifndef LTT_N_SUBBUFS |
33 | #define LTT_N_SUBBUFS 2 |
34 | #endif //LTT_N_SUBBUFS |
35 | |
b402c055 |
36 | #ifndef LTT_SUBBUF_SIZE_PROCESS |
37 | #define LTT_SUBBUF_SIZE_PROCESS 1048576 |
51bf1553 |
38 | #endif //LTT_BUF_SIZE_CPU |
b09f3215 |
39 | |
b402c055 |
40 | #define LTT_BUF_SIZE_PROCESS (LTT_SUBBUF_SIZE_PROCESS * LTT_N_SUBBUFS) |
47d7d576 |
41 | |
77b31f39 |
42 | #ifndef LTT_USERTRACE_ROOT |
43 | #define LTT_USERTRACE_ROOT "/tmp/ltt-usertrace" |
44 | #endif //LTT_USERTRACE_ROOT |
45 | |
47d7d576 |
46 | |
47 | /* Buffer offset macros */ |
48 | |
49 | #define BUFFER_OFFSET(offset, buf) (offset & (buf->alloc_size-1)) |
50 | #define SUBBUF_OFFSET(offset, buf) (offset & (buf->subbuf_size-1)) |
51 | #define SUBBUF_ALIGN(offset, buf) \ |
52 | (((offset) + buf->subbuf_size) & (~(buf->subbuf_size-1))) |
53 | #define SUBBUF_TRUNC(offset, buf) \ |
54 | ((offset) & (~(buf->subbuf_size-1))) |
55 | #define SUBBUF_INDEX(offset, buf) \ |
56 | (BUFFER_OFFSET(offset,buf)/buf->subbuf_size) |
57 | |
58 | |
32f2b04a |
59 | #define LTT_TRACER_MAGIC_NUMBER 0x00D6B7ED |
60 | #define LTT_TRACER_VERSION_MAJOR 0 |
61 | #define LTT_TRACER_VERSION_MINOR 7 |
62 | |
63 | #ifndef atomic_cmpxchg |
64 | #define atomic_cmpxchg(v, old, new) ((int)cmpxchg(&((v)->counter), old, new)) |
65 | #endif //atomic_cmpxchg |
5ffa9d14 |
66 | |
67 | typedef unsigned int ltt_facility_t; |
68 | |
32f2b04a |
69 | struct ltt_trace_header { |
70 | uint32_t magic_number; |
71 | uint32_t arch_type; |
72 | uint32_t arch_variant; |
73 | uint32_t float_word_order; /* Only useful for user space traces */ |
74 | uint8_t arch_size; |
75 | //uint32_t system_type; |
76 | uint8_t major_version; |
77 | uint8_t minor_version; |
78 | uint8_t flight_recorder; |
79 | uint8_t has_heartbeat; |
80 | uint8_t has_alignment; /* Event header alignment */ |
81 | uint32_t freq_scale; |
82 | uint64_t start_freq; |
83 | uint64_t start_tsc; |
84 | uint64_t start_monotonic; |
85 | uint64_t start_time_sec; |
86 | uint64_t start_time_usec; |
87 | } __attribute((packed)); |
88 | |
89 | |
90 | struct ltt_block_start_header { |
91 | struct { |
92 | uint64_t cycle_count; |
93 | uint64_t freq; /* khz */ |
94 | } begin; |
95 | struct { |
96 | uint64_t cycle_count; |
97 | uint64_t freq; /* khz */ |
98 | } end; |
99 | uint32_t lost_size; /* Size unused at the end of the buffer */ |
100 | uint32_t buf_size; /* The size of this sub-buffer */ |
101 | struct ltt_trace_header trace; |
102 | } __attribute((packed)); |
103 | |
104 | |
105 | |
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106 | struct ltt_buf { |
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107 | void *start; |
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108 | atomic_t offset; |
47d7d576 |
109 | atomic_t consumed; |
110 | atomic_t reserve_count[LTT_N_SUBBUFS]; |
111 | atomic_t commit_count[LTT_N_SUBBUFS]; |
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112 | |
113 | atomic_t events_lost; |
32f2b04a |
114 | atomic_t corrupted_subbuffers; |
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115 | atomic_t writer_futex; /* futex on which the writer waits */ |
47d7d576 |
116 | unsigned int alloc_size; |
117 | unsigned int subbuf_size; |
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118 | }; |
119 | |
700d350d |
120 | struct ltt_trace_info { |
1c48e587 |
121 | int init; |
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122 | int filter; |
700d350d |
123 | pid_t daemon_id; |
8b30e7bc |
124 | int nesting; |
b09f3215 |
125 | struct { |
b402c055 |
126 | struct ltt_buf process; |
127 | char process_buf[LTT_BUF_SIZE_PROCESS] __attribute__ ((aligned (8))); |
b09f3215 |
128 | } channel; |
129 | }; |
130 | |
32f2b04a |
131 | |
5ffa9d14 |
132 | struct ltt_event_header_nohb { |
133 | uint64_t timestamp; |
134 | unsigned char facility_id; |
135 | unsigned char event_id; |
136 | uint16_t event_size; |
137 | } __attribute((packed)); |
32f2b04a |
138 | |
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139 | extern __thread struct ltt_trace_info *thread_trace_info; |
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140 | |
51bf1553 |
141 | void ltt_thread_init(void); |
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142 | |
5ffa9d14 |
143 | void __attribute__((no_instrument_function)) |
144 | ltt_usertrace_fast_buffer_switch(void); |
145 | |
5ffa9d14 |
146 | /* Get the offset of the channel in the ltt_trace_struct */ |
147 | #define GET_CHANNEL_INDEX(chan) \ |
148 | (unsigned int)&((struct ltt_trace_info*)NULL)->channel.chan |
149 | |
150 | /* ltt_get_index_from_facility |
151 | * |
152 | * Get channel index from facility and event id. |
153 | * |
154 | * @fID : facility ID |
155 | * @eID : event number |
156 | * |
157 | * Get the channel index into which events must be written for the given |
158 | * facility and event number. We get this structure offset as soon as possible |
159 | * and remember it so we pass through this logic only once per trace call (not |
160 | * for every trace). |
161 | */ |
162 | static inline unsigned int __attribute__((no_instrument_function)) |
163 | ltt_get_index_from_facility(ltt_facility_t fID, |
164 | uint8_t eID) |
165 | { |
b402c055 |
166 | return GET_CHANNEL_INDEX(process); |
5ffa9d14 |
167 | } |
168 | |
169 | |
170 | static inline struct ltt_buf * __attribute__((no_instrument_function)) |
171 | ltt_get_channel_from_index( |
172 | struct ltt_trace_info *trace, unsigned int index) |
173 | { |
b5d612cb |
174 | return (struct ltt_buf *)((void*)trace+index); |
5ffa9d14 |
175 | } |
176 | |
177 | |
178 | /* |
179 | * ltt_get_header_size |
180 | * |
181 | * Calculate alignment offset for arch size void*. This is the |
182 | * alignment offset of the event header. |
183 | * |
184 | * Important note : |
185 | * The event header must be a size multiple of the void* size. This is necessary |
186 | * to be able to calculate statically the alignment offset of the variable |
187 | * length data fields that follows. The total offset calculated here : |
188 | * |
189 | * Alignment of header struct on arch size |
190 | * + sizeof(header struct) |
191 | * + padding added to end of struct to align on arch size. |
192 | * */ |
193 | static inline unsigned char __attribute__((no_instrument_function)) |
194 | ltt_get_header_size(struct ltt_trace_info *trace, |
195 | void *address, |
196 | size_t *before_hdr_pad, |
197 | size_t *after_hdr_pad, |
198 | size_t *header_size) |
199 | { |
200 | unsigned int padding; |
201 | unsigned int header; |
202 | |
203 | header = sizeof(struct ltt_event_header_nohb); |
204 | |
205 | /* Padding before the header. Calculated dynamically */ |
206 | *before_hdr_pad = ltt_align((unsigned long)address, header); |
207 | padding = *before_hdr_pad; |
208 | |
209 | /* Padding after header, considering header aligned on ltt_align. |
210 | * Calculated statically if header size if known. */ |
211 | *after_hdr_pad = ltt_align(header, sizeof(void*)); |
212 | padding += *after_hdr_pad; |
213 | |
214 | *header_size = header; |
215 | |
216 | return header+padding; |
217 | } |
218 | |
219 | |
220 | /* ltt_write_event_header |
221 | * |
222 | * Writes the event header to the pointer. |
223 | * |
224 | * @channel : pointer to the channel structure |
225 | * @ptr : buffer pointer |
226 | * @fID : facility ID |
227 | * @eID : event ID |
228 | * @event_size : size of the event, excluding the event header. |
229 | * @offset : offset of the beginning of the header, for alignment. |
230 | * Calculated by ltt_get_event_header_size. |
231 | * @tsc : time stamp counter. |
232 | */ |
233 | static inline void __attribute__((no_instrument_function)) |
234 | ltt_write_event_header( |
235 | struct ltt_trace_info *trace, struct ltt_buf *buf, |
236 | void *ptr, ltt_facility_t fID, uint32_t eID, size_t event_size, |
237 | size_t offset, uint64_t tsc) |
238 | { |
239 | struct ltt_event_header_nohb *nohb; |
240 | |
241 | event_size = min(event_size, 0xFFFFU); |
242 | nohb = (struct ltt_event_header_nohb *)(ptr+offset); |
243 | nohb->timestamp = (uint64_t)tsc; |
244 | nohb->facility_id = fID; |
245 | nohb->event_id = eID; |
246 | nohb->event_size = (uint16_t)event_size; |
247 | } |
700d350d |
248 | |
32f2b04a |
249 | |
250 | |
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251 | static inline uint64_t __attribute__((no_instrument_function)) |
252 | ltt_get_timestamp() |
32f2b04a |
253 | { |
254 | return get_cycles(); |
255 | } |
256 | |
5ffa9d14 |
257 | static inline unsigned int __attribute__((no_instrument_function)) |
258 | ltt_subbuf_header_len(struct ltt_buf *buf) |
32f2b04a |
259 | { |
260 | return sizeof(struct ltt_block_start_header); |
261 | } |
262 | |
263 | |
264 | |
5ffa9d14 |
265 | static inline void __attribute__((no_instrument_function)) |
266 | ltt_write_trace_header(struct ltt_trace_header *header) |
32f2b04a |
267 | { |
268 | header->magic_number = LTT_TRACER_MAGIC_NUMBER; |
269 | header->major_version = LTT_TRACER_VERSION_MAJOR; |
270 | header->minor_version = LTT_TRACER_VERSION_MINOR; |
271 | header->float_word_order = 0; //FIXME |
272 | header->arch_type = 0; //FIXME LTT_ARCH_TYPE; |
273 | header->arch_size = sizeof(void*); |
274 | header->arch_variant = 0; //FIXME LTT_ARCH_VARIANT; |
275 | header->flight_recorder = 0; |
276 | header->has_heartbeat = 0; |
277 | |
5ffa9d14 |
278 | #ifndef LTT_PACK |
32f2b04a |
279 | header->has_alignment = sizeof(void*); |
280 | #else |
281 | header->has_alignment = 0; |
282 | #endif |
283 | |
284 | //FIXME |
285 | header->freq_scale = 0; |
286 | header->start_freq = 0; |
287 | header->start_tsc = 0; |
288 | header->start_monotonic = 0; |
289 | header->start_time_sec = 0; |
290 | header->start_time_usec = 0; |
291 | } |
292 | |
293 | |
5ffa9d14 |
294 | static inline void __attribute__((no_instrument_function)) |
295 | ltt_buffer_begin_callback(struct ltt_buf *buf, |
32f2b04a |
296 | uint64_t tsc, unsigned int subbuf_idx) |
297 | { |
298 | struct ltt_block_start_header *header = |
299 | (struct ltt_block_start_header*) |
300 | (buf->start + (subbuf_idx*buf->subbuf_size)); |
301 | |
302 | header->begin.cycle_count = tsc; |
303 | header->begin.freq = 0; //ltt_frequency(); |
304 | |
305 | header->lost_size = 0xFFFFFFFF; // for debugging... |
306 | |
307 | header->buf_size = buf->subbuf_size; |
308 | |
309 | ltt_write_trace_header(&header->trace); |
310 | |
311 | } |
312 | |
313 | |
314 | |
5ffa9d14 |
315 | static inline void __attribute__((no_instrument_function)) |
316 | ltt_buffer_end_callback(struct ltt_buf *buf, |
32f2b04a |
317 | uint64_t tsc, unsigned int offset, unsigned int subbuf_idx) |
318 | { |
319 | struct ltt_block_start_header *header = |
320 | (struct ltt_block_start_header*) |
321 | (buf->start + (subbuf_idx*buf->subbuf_size)); |
322 | /* offset is assumed to never be 0 here : never deliver a completely |
323 | * empty subbuffer. */ |
324 | /* The lost size is between 0 and subbuf_size-1 */ |
325 | header->lost_size = SUBBUF_OFFSET((buf->subbuf_size - offset), |
326 | buf); |
327 | header->end.cycle_count = tsc; |
328 | header->end.freq = 0; //ltt_frequency(); |
329 | } |
330 | |
331 | |
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332 | static inline void __attribute__((no_instrument_function)) |
333 | ltt_deliver_callback(struct ltt_buf *buf, |
32f2b04a |
334 | unsigned subbuf_idx, |
335 | void *subbuf) |
336 | { |
337 | ltt_usertrace_fast_buffer_switch(); |
338 | } |
5ffa9d14 |
339 | |
340 | |
341 | /* ltt_reserve_slot |
342 | * |
343 | * Atomic slot reservation in a LTTng buffer. It will take care of |
344 | * sub-buffer switching. |
345 | * |
346 | * Parameters: |
347 | * |
348 | * @trace : the trace structure to log to. |
349 | * @buf : the buffer to reserve space into. |
350 | * @data_size : size of the variable length data to log. |
351 | * @slot_size : pointer to total size of the slot (out) |
352 | * @tsc : pointer to the tsc at the slot reservation (out) |
353 | * @before_hdr_pad : dynamic padding before the event header. |
354 | * @after_hdr_pad : dynamic padding after the event header. |
355 | * |
356 | * Return : NULL if not enough space, else returns the pointer |
357 | * to the beginning of the reserved slot. */ |
358 | static inline void * __attribute__((no_instrument_function)) ltt_reserve_slot( |
359 | struct ltt_trace_info *trace, |
360 | struct ltt_buf *ltt_buf, |
361 | unsigned int data_size, |
362 | unsigned int *slot_size, |
363 | uint64_t *tsc, |
364 | size_t *before_hdr_pad, |
365 | size_t *after_hdr_pad, |
366 | size_t *header_size) |
367 | { |
368 | int offset_begin, offset_end, offset_old; |
369 | //int has_switch; |
370 | int begin_switch, end_switch_current, end_switch_old; |
371 | int reserve_commit_diff = 0; |
372 | unsigned int size; |
373 | int consumed_old, consumed_new; |
374 | int commit_count, reserve_count; |
375 | int ret; |
376 | |
377 | do { |
378 | offset_old = atomic_read(<t_buf->offset); |
379 | offset_begin = offset_old; |
380 | //has_switch = 0; |
381 | begin_switch = 0; |
382 | end_switch_current = 0; |
383 | end_switch_old = 0; |
384 | *tsc = ltt_get_timestamp(); |
385 | if(*tsc == 0) { |
386 | /* Error in getting the timestamp, event lost */ |
387 | atomic_inc(<t_buf->events_lost); |
388 | return NULL; |
389 | } |
390 | |
391 | if(SUBBUF_OFFSET(offset_begin, ltt_buf) == 0) { |
392 | begin_switch = 1; /* For offset_begin */ |
393 | } else { |
394 | size = ltt_get_header_size(trace, ltt_buf->start + offset_begin, |
395 | before_hdr_pad, after_hdr_pad, header_size) |
396 | + data_size; |
397 | |
398 | if((SUBBUF_OFFSET(offset_begin, ltt_buf)+size)>ltt_buf->subbuf_size) { |
399 | //has_switch = 1; |
400 | end_switch_old = 1; /* For offset_old */ |
401 | begin_switch = 1; /* For offset_begin */ |
402 | } |
403 | } |
404 | |
405 | if(begin_switch) { |
406 | if(end_switch_old) { |
407 | offset_begin = SUBBUF_ALIGN(offset_begin, ltt_buf); |
408 | } |
409 | offset_begin = offset_begin + ltt_subbuf_header_len(ltt_buf); |
410 | /* Test new buffer integrity */ |
411 | reserve_commit_diff = |
412 | atomic_read(<t_buf->reserve_count[SUBBUF_INDEX(offset_begin, |
413 | ltt_buf)]) |
414 | - atomic_read(<t_buf->commit_count[SUBBUF_INDEX(offset_begin, |
415 | ltt_buf)]); |
416 | if(reserve_commit_diff == 0) { |
417 | /* Next buffer not corrupted. */ |
b402c055 |
418 | //if((SUBBUF_TRUNC(offset_begin, ltt_buf) |
419 | // - SUBBUF_TRUNC(atomic_read(<t_buf->consumed), ltt_buf)) |
420 | // >= ltt_buf->alloc_size) { |
421 | if(atomic_dec_return(<t_buf->writer_futex) >= 0) { |
422 | /* non contended */ |
423 | } else { |
424 | /* We block until the reader unblocks us */ |
425 | atomic_set(<t_buf->writer_futex, -1); |
426 | /* We block until the reader tells us to wake up. |
427 | Signals will simply cause this loop to restart. |
428 | */ |
429 | do { |
430 | ret = futex((unsigned long)<t_buf->writer_futex, |
431 | FUTEX_WAIT, -1, 0, 0, 0); |
432 | } while(ret != 0 && ret != EWOULDBLOCK); |
433 | } |
5ffa9d14 |
434 | /* go on with the write */ |
435 | |
b402c055 |
436 | //} else { |
437 | // /* next buffer not corrupted, we are either in overwrite mode or |
438 | // * the buffer is not full. It's safe to write in this new subbuffer.*/ |
439 | //} |
5ffa9d14 |
440 | } else { |
441 | /* Next subbuffer corrupted. Force pushing reader even in normal |
442 | * mode. It's safe to write in this new subbuffer. */ |
443 | } |
444 | size = ltt_get_header_size(trace, ltt_buf->start + offset_begin, |
445 | before_hdr_pad, after_hdr_pad, header_size) + data_size; |
446 | if((SUBBUF_OFFSET(offset_begin,ltt_buf)+size)>ltt_buf->subbuf_size) { |
447 | /* Event too big for subbuffers, report error, don't complete |
448 | * the sub-buffer switch. */ |
449 | atomic_inc(<t_buf->events_lost); |
450 | return NULL; |
451 | } else { |
452 | /* We just made a successful buffer switch and the event fits in the |
453 | * new subbuffer. Let's write. */ |
454 | } |
455 | } else { |
456 | /* Event fits in the current buffer and we are not on a switch boundary. |
457 | * It's safe to write */ |
458 | } |
459 | offset_end = offset_begin + size; |
460 | |
461 | if((SUBBUF_OFFSET(offset_end, ltt_buf)) == 0) { |
462 | /* The offset_end will fall at the very beginning of the next subbuffer. |
463 | */ |
464 | end_switch_current = 1; /* For offset_begin */ |
465 | } |
466 | |
467 | } while(atomic_cmpxchg(<t_buf->offset, offset_old, offset_end) |
468 | != offset_old); |
469 | |
470 | |
471 | /* Push the reader if necessary */ |
472 | do { |
473 | consumed_old = atomic_read(<t_buf->consumed); |
474 | /* If buffer is in overwrite mode, push the reader consumed count if |
475 | the write position has reached it and we are not at the first |
476 | iteration (don't push the reader farther than the writer). |
477 | This operation can be done concurrently by many writers in the |
478 | same buffer, the writer being at the fartest write position sub-buffer |
479 | index in the buffer being the one which will win this loop. */ |
480 | /* If the buffer is not in overwrite mode, pushing the reader only |
481 | happen if a sub-buffer is corrupted */ |
482 | if((SUBBUF_TRUNC(offset_end, ltt_buf) |
483 | - SUBBUF_TRUNC(consumed_old, ltt_buf)) |
484 | >= ltt_buf->alloc_size) |
485 | consumed_new = SUBBUF_ALIGN(consumed_old, ltt_buf); |
486 | else { |
487 | consumed_new = consumed_old; |
488 | break; |
489 | } |
490 | } while(atomic_cmpxchg(<t_buf->consumed, consumed_old, consumed_new) |
491 | != consumed_old); |
492 | |
493 | if(consumed_old != consumed_new) { |
494 | /* Reader pushed : we are the winner of the push, we can therefore |
495 | reequilibrate reserve and commit. Atomic increment of the commit |
496 | count permits other writers to play around with this variable |
497 | before us. We keep track of corrupted_subbuffers even in overwrite mode : |
498 | we never want to write over a non completely committed sub-buffer : |
499 | possible causes : the buffer size is too low compared to the unordered |
500 | data input, or there is a writer who died between the reserve and the |
501 | commit. */ |
502 | if(reserve_commit_diff) { |
503 | /* We have to alter the sub-buffer commit count : a sub-buffer is |
504 | corrupted. We do not deliver it. */ |
505 | atomic_add(reserve_commit_diff, |
506 | <t_buf->commit_count[SUBBUF_INDEX(offset_begin, ltt_buf)]); |
507 | atomic_inc(<t_buf->corrupted_subbuffers); |
508 | } |
509 | } |
510 | |
511 | |
512 | if(end_switch_old) { |
513 | /* old subbuffer */ |
514 | /* Concurrency safe because we are the last and only thread to alter this |
515 | sub-buffer. As long as it is not delivered and read, no other thread can |
516 | alter the offset, alter the reserve_count or call the |
517 | client_buffer_end_callback on this sub-buffer. |
518 | The only remaining threads could be the ones with pending commits. They |
519 | will have to do the deliver themself. |
520 | Not concurrency safe in overwrite mode. We detect corrupted subbuffers |
521 | with commit and reserve counts. We keep a corrupted sub-buffers count |
522 | and push the readers across these sub-buffers. |
523 | Not concurrency safe if a writer is stalled in a subbuffer and |
524 | another writer switches in, finding out it's corrupted. The result will |
525 | be than the old (uncommited) subbuffer will be declared corrupted, and |
526 | that the new subbuffer will be declared corrupted too because of the |
527 | commit count adjustment. |
528 | Note : offset_old should never be 0 here.*/ |
529 | ltt_buffer_end_callback(ltt_buf, *tsc, offset_old, |
530 | SUBBUF_INDEX((offset_old-1), ltt_buf)); |
531 | /* Setting this reserve_count will allow the sub-buffer to be delivered by |
532 | the last committer. */ |
533 | reserve_count = |
534 | atomic_add_return((SUBBUF_OFFSET((offset_old-1), ltt_buf)+1), |
535 | <t_buf->reserve_count[SUBBUF_INDEX((offset_old-1), ltt_buf)]); |
536 | if(reserve_count |
537 | == atomic_read(<t_buf->commit_count[SUBBUF_INDEX((offset_old-1), |
538 | ltt_buf)])) { |
539 | ltt_deliver_callback(ltt_buf, SUBBUF_INDEX((offset_old-1), ltt_buf), |
540 | NULL); |
541 | } |
542 | } |
543 | |
544 | if(begin_switch) { |
545 | /* New sub-buffer */ |
546 | /* This code can be executed unordered : writers may already have written |
547 | to the sub-buffer before this code gets executed, caution. */ |
548 | /* The commit makes sure that this code is executed before the deliver |
549 | of this sub-buffer */ |
550 | ltt_buffer_begin_callback(ltt_buf, *tsc, SUBBUF_INDEX(offset_begin, ltt_buf)); |
551 | commit_count = atomic_add_return(ltt_subbuf_header_len(ltt_buf), |
552 | <t_buf->commit_count[SUBBUF_INDEX(offset_begin, ltt_buf)]); |
553 | /* Check if the written buffer has to be delivered */ |
554 | if(commit_count |
555 | == atomic_read(<t_buf->reserve_count[SUBBUF_INDEX(offset_begin, |
556 | ltt_buf)])) { |
557 | ltt_deliver_callback(ltt_buf, SUBBUF_INDEX(offset_begin, ltt_buf), NULL); |
558 | } |
559 | } |
560 | |
561 | if(end_switch_current) { |
562 | /* current subbuffer */ |
563 | /* Concurrency safe because we are the last and only thread to alter this |
564 | sub-buffer. As long as it is not delivered and read, no other thread can |
565 | alter the offset, alter the reserve_count or call the |
566 | client_buffer_end_callback on this sub-buffer. |
567 | The only remaining threads could be the ones with pending commits. They |
568 | will have to do the deliver themself. |
569 | Not concurrency safe in overwrite mode. We detect corrupted subbuffers |
570 | with commit and reserve counts. We keep a corrupted sub-buffers count |
571 | and push the readers across these sub-buffers. |
572 | Not concurrency safe if a writer is stalled in a subbuffer and |
573 | another writer switches in, finding out it's corrupted. The result will |
574 | be than the old (uncommited) subbuffer will be declared corrupted, and |
575 | that the new subbuffer will be declared corrupted too because of the |
576 | commit count adjustment. */ |
577 | ltt_buffer_end_callback(ltt_buf, *tsc, offset_end, |
578 | SUBBUF_INDEX((offset_end-1), ltt_buf)); |
579 | /* Setting this reserve_count will allow the sub-buffer to be delivered by |
580 | the last committer. */ |
581 | reserve_count = |
582 | atomic_add_return((SUBBUF_OFFSET((offset_end-1), ltt_buf)+1), |
583 | <t_buf->reserve_count[SUBBUF_INDEX((offset_end-1), ltt_buf)]); |
584 | if(reserve_count |
585 | == atomic_read(<t_buf->commit_count[SUBBUF_INDEX((offset_end-1), |
586 | ltt_buf)])) { |
587 | ltt_deliver_callback(ltt_buf, SUBBUF_INDEX((offset_end-1), ltt_buf), NULL); |
588 | } |
589 | } |
590 | |
591 | *slot_size = size; |
592 | |
593 | //BUG_ON(*slot_size != (data_size + *before_hdr_pad + *after_hdr_pad + *header_size)); |
594 | //BUG_ON(*slot_size != (offset_end - offset_begin)); |
595 | |
596 | return ltt_buf->start + BUFFER_OFFSET(offset_begin, ltt_buf); |
597 | } |
598 | |
599 | |
600 | /* ltt_commit_slot |
601 | * |
602 | * Atomic unordered slot commit. Increments the commit count in the |
603 | * specified sub-buffer, and delivers it if necessary. |
604 | * |
605 | * Parameters: |
606 | * |
607 | * @buf : the buffer to commit to. |
608 | * @reserved : address of the beginnig of the reserved slot. |
609 | * @slot_size : size of the reserved slot. |
610 | * |
611 | */ |
612 | static inline void __attribute__((no_instrument_function)) ltt_commit_slot( |
613 | struct ltt_buf *ltt_buf, |
614 | void *reserved, |
615 | unsigned int slot_size) |
616 | { |
617 | unsigned int offset_begin = reserved - ltt_buf->start; |
618 | int commit_count; |
619 | |
620 | commit_count = atomic_add_return(slot_size, |
621 | <t_buf->commit_count[SUBBUF_INDEX(offset_begin, |
622 | ltt_buf)]); |
623 | |
624 | /* Check if all commits have been done */ |
625 | if(commit_count == |
626 | atomic_read(<t_buf->reserve_count[SUBBUF_INDEX(offset_begin, ltt_buf)])) { |
627 | ltt_deliver_callback(ltt_buf, SUBBUF_INDEX(offset_begin, ltt_buf), NULL); |
628 | } |
629 | } |
630 | |
631 | |
8b30e7bc |
632 | #endif //LTT_TRACE |
5ffa9d14 |
633 | |
634 | |
04180f7f |
635 | #endif //_LTT_USERTRACE_FAST_H |