Commit | Line | Data |
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852c2936 MD |
1 | /* |
2 | * ring_buffer_frontend.c | |
3 | * | |
e92f3e28 MD |
4 | * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
5 | * | |
6 | * This library is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU Lesser General Public | |
8 | * License as published by the Free Software Foundation; only | |
9 | * version 2.1 of the License. | |
10 | * | |
11 | * This library is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | * Lesser General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU Lesser General Public | |
17 | * License along with this library; if not, write to the Free Software | |
18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
19 | * | |
852c2936 MD |
20 | * |
21 | * Ring buffer wait-free buffer synchronization. Producer-consumer and flight | |
22 | * recorder (overwrite) modes. See thesis: | |
23 | * | |
24 | * Desnoyers, Mathieu (2009), "Low-Impact Operating System Tracing", Ph.D. | |
25 | * dissertation, Ecole Polytechnique de Montreal. | |
26 | * http://www.lttng.org/pub/thesis/desnoyers-dissertation-2009-12.pdf | |
27 | * | |
28 | * - Algorithm presentation in Chapter 5: | |
29 | * "Lockless Multi-Core High-Throughput Buffering". | |
30 | * - Algorithm formal verification in Section 8.6: | |
31 | * "Formal verification of LTTng" | |
32 | * | |
33 | * Author: | |
34 | * Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
35 | * | |
36 | * Inspired from LTT and RelayFS: | |
37 | * Karim Yaghmour <karim@opersys.com> | |
38 | * Tom Zanussi <zanussi@us.ibm.com> | |
39 | * Bob Wisniewski <bob@watson.ibm.com> | |
40 | * And from K42 : | |
41 | * Bob Wisniewski <bob@watson.ibm.com> | |
42 | * | |
43 | * Buffer reader semantic : | |
44 | * | |
45 | * - get_subbuf_size | |
46 | * while buffer is not finalized and empty | |
47 | * - get_subbuf | |
48 | * - if return value != 0, continue | |
49 | * - splice one subbuffer worth of data to a pipe | |
50 | * - splice the data from pipe to disk/network | |
51 | * - put_subbuf | |
852c2936 MD |
52 | */ |
53 | ||
5ad63a16 | 54 | #define _GNU_SOURCE |
a6352fd4 | 55 | #include <sys/types.h> |
431d5cf0 MD |
56 | #include <sys/mman.h> |
57 | #include <sys/stat.h> | |
03d2d293 | 58 | #include <unistd.h> |
431d5cf0 | 59 | #include <fcntl.h> |
03d2d293 MD |
60 | #include <signal.h> |
61 | #include <time.h> | |
14641deb | 62 | #include <urcu/compiler.h> |
a6352fd4 | 63 | #include <urcu/ref.h> |
8c90a710 | 64 | #include <urcu/tls-compat.h> |
b3bfefa2 | 65 | #include <poll.h> |
35897f8b | 66 | #include <helper.h> |
14641deb | 67 | |
a6352fd4 | 68 | #include "smp.h" |
4318ae1b | 69 | #include <lttng/ringbuffer-config.h> |
2fed87ae | 70 | #include "vatomic.h" |
4931a13e MD |
71 | #include "backend.h" |
72 | #include "frontend.h" | |
a6352fd4 | 73 | #include "shm.h" |
f645cfa7 | 74 | #include "tlsfixup.h" |
bdcf8d82 | 75 | #include "../liblttng-ust/compat.h" /* For ENODATA */ |
852c2936 | 76 | |
431d5cf0 MD |
77 | #ifndef max |
78 | #define max(a, b) ((a) > (b) ? (a) : (b)) | |
79 | #endif | |
80 | ||
64493e4f MD |
81 | /* Print DBG() messages about events lost only every 1048576 hits */ |
82 | #define DBG_PRINT_NR_LOST (1UL << 20) | |
83 | ||
34a91bdb MD |
84 | #define LTTNG_UST_RB_SIG_FLUSH SIGRTMIN |
85 | #define LTTNG_UST_RB_SIG_READ SIGRTMIN + 1 | |
86 | #define LTTNG_UST_RB_SIG_TEARDOWN SIGRTMIN + 2 | |
03d2d293 | 87 | #define CLOCKID CLOCK_MONOTONIC |
87edc338 MD |
88 | #define LTTNG_UST_RING_BUFFER_GET_RETRY 10 |
89 | #define LTTNG_UST_RING_BUFFER_RETRY_DELAY_MS 10 | |
03d2d293 | 90 | |
2432c3c9 MD |
91 | /* |
92 | * Use POSIX SHM: shm_open(3) and shm_unlink(3). | |
93 | * close(2) to close the fd returned by shm_open. | |
94 | * shm_unlink releases the shared memory object name. | |
95 | * ftruncate(2) sets the size of the memory object. | |
96 | * mmap/munmap maps the shared memory obj to a virtual address in the | |
97 | * calling proceess (should be done both in libust and consumer). | |
98 | * See shm_overview(7) for details. | |
99 | * Pass file descriptor returned by shm_open(3) to ltt-sessiond through | |
100 | * a UNIX socket. | |
101 | * | |
102 | * Since we don't need to access the object using its name, we can | |
103 | * immediately shm_unlink(3) it, and only keep the handle with its file | |
104 | * descriptor. | |
105 | */ | |
106 | ||
852c2936 MD |
107 | /* |
108 | * Internal structure representing offsets to use at a sub-buffer switch. | |
109 | */ | |
110 | struct switch_offsets { | |
111 | unsigned long begin, end, old; | |
112 | size_t pre_header_padding, size; | |
1ad21f70 MD |
113 | unsigned int switch_new_start:1, switch_new_end:1, switch_old_start:1, |
114 | switch_old_end:1; | |
852c2936 MD |
115 | }; |
116 | ||
8c90a710 | 117 | DEFINE_URCU_TLS(unsigned int, lib_ring_buffer_nesting); |
852c2936 | 118 | |
cb7378b3 MD |
119 | /* |
120 | * wakeup_fd_mutex protects wakeup fd use by timer from concurrent | |
121 | * close. | |
122 | */ | |
123 | static pthread_mutex_t wakeup_fd_mutex = PTHREAD_MUTEX_INITIALIZER; | |
124 | ||
852c2936 MD |
125 | static |
126 | void lib_ring_buffer_print_errors(struct channel *chan, | |
009769ca MD |
127 | struct lttng_ust_lib_ring_buffer *buf, int cpu, |
128 | struct lttng_ust_shm_handle *handle); | |
852c2936 | 129 | |
03d2d293 MD |
130 | /* |
131 | * Handle timer teardown race wrt memory free of private data by | |
132 | * ring buffer signals are handled by a single thread, which permits | |
133 | * a synchronization point between handling of each signal. | |
64bf51a6 | 134 | * Protected by the lock within the structure. |
03d2d293 MD |
135 | */ |
136 | struct timer_signal_data { | |
137 | pthread_t tid; /* thread id managing signals */ | |
138 | int setup_done; | |
139 | int qs_done; | |
64bf51a6 | 140 | pthread_mutex_t lock; |
03d2d293 MD |
141 | }; |
142 | ||
64bf51a6 MD |
143 | static struct timer_signal_data timer_signal = { |
144 | .tid = 0, | |
145 | .setup_done = 0, | |
146 | .qs_done = 0, | |
147 | .lock = PTHREAD_MUTEX_INITIALIZER, | |
148 | }; | |
03d2d293 | 149 | |
852c2936 MD |
150 | /** |
151 | * lib_ring_buffer_reset - Reset ring buffer to initial values. | |
152 | * @buf: Ring buffer. | |
153 | * | |
154 | * Effectively empty the ring buffer. Should be called when the buffer is not | |
155 | * used for writing. The ring buffer can be opened for reading, but the reader | |
156 | * should not be using the iterator concurrently with reset. The previous | |
157 | * current iterator record is reset. | |
158 | */ | |
4cfec15c | 159 | void lib_ring_buffer_reset(struct lttng_ust_lib_ring_buffer *buf, |
38fae1d3 | 160 | struct lttng_ust_shm_handle *handle) |
852c2936 | 161 | { |
f680d83c MD |
162 | struct channel *chan; |
163 | const struct lttng_ust_lib_ring_buffer_config *config; | |
852c2936 MD |
164 | unsigned int i; |
165 | ||
f680d83c MD |
166 | chan = shmp(handle, buf->backend.chan); |
167 | if (!chan) | |
168 | abort(); | |
169 | config = &chan->backend.config; | |
852c2936 MD |
170 | /* |
171 | * Reset iterator first. It will put the subbuffer if it currently holds | |
172 | * it. | |
173 | */ | |
852c2936 MD |
174 | v_set(config, &buf->offset, 0); |
175 | for (i = 0; i < chan->backend.num_subbuf; i++) { | |
4746ae29 MD |
176 | v_set(config, &shmp_index(handle, buf->commit_hot, i)->cc, 0); |
177 | v_set(config, &shmp_index(handle, buf->commit_hot, i)->seq, 0); | |
178 | v_set(config, &shmp_index(handle, buf->commit_cold, i)->cc_sb, 0); | |
852c2936 | 179 | } |
a6352fd4 MD |
180 | uatomic_set(&buf->consumed, 0); |
181 | uatomic_set(&buf->record_disabled, 0); | |
852c2936 | 182 | v_set(config, &buf->last_tsc, 0); |
1d498196 | 183 | lib_ring_buffer_backend_reset(&buf->backend, handle); |
852c2936 MD |
184 | /* Don't reset number of active readers */ |
185 | v_set(config, &buf->records_lost_full, 0); | |
186 | v_set(config, &buf->records_lost_wrap, 0); | |
187 | v_set(config, &buf->records_lost_big, 0); | |
188 | v_set(config, &buf->records_count, 0); | |
189 | v_set(config, &buf->records_overrun, 0); | |
190 | buf->finalized = 0; | |
191 | } | |
852c2936 MD |
192 | |
193 | /** | |
194 | * channel_reset - Reset channel to initial values. | |
195 | * @chan: Channel. | |
196 | * | |
197 | * Effectively empty the channel. Should be called when the channel is not used | |
198 | * for writing. The channel can be opened for reading, but the reader should not | |
199 | * be using the iterator concurrently with reset. The previous current iterator | |
200 | * record is reset. | |
201 | */ | |
202 | void channel_reset(struct channel *chan) | |
203 | { | |
204 | /* | |
205 | * Reset iterators first. Will put the subbuffer if held for reading. | |
206 | */ | |
a6352fd4 | 207 | uatomic_set(&chan->record_disabled, 0); |
852c2936 MD |
208 | /* Don't reset commit_count_mask, still valid */ |
209 | channel_backend_reset(&chan->backend); | |
210 | /* Don't reset switch/read timer interval */ | |
211 | /* Don't reset notifiers and notifier enable bits */ | |
212 | /* Don't reset reader reference count */ | |
213 | } | |
852c2936 MD |
214 | |
215 | /* | |
216 | * Must be called under cpu hotplug protection. | |
217 | */ | |
4cfec15c | 218 | int lib_ring_buffer_create(struct lttng_ust_lib_ring_buffer *buf, |
a6352fd4 | 219 | struct channel_backend *chanb, int cpu, |
38fae1d3 | 220 | struct lttng_ust_shm_handle *handle, |
1d498196 | 221 | struct shm_object *shmobj) |
852c2936 | 222 | { |
4cfec15c | 223 | const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config; |
14641deb | 224 | struct channel *chan = caa_container_of(chanb, struct channel, backend); |
a3f61e7f | 225 | void *priv = channel_get_private(chan); |
852c2936 | 226 | size_t subbuf_header_size; |
2fed87ae | 227 | uint64_t tsc; |
852c2936 MD |
228 | int ret; |
229 | ||
230 | /* Test for cpu hotplug */ | |
231 | if (buf->backend.allocated) | |
232 | return 0; | |
233 | ||
a6352fd4 | 234 | ret = lib_ring_buffer_backend_create(&buf->backend, &chan->backend, |
1d498196 | 235 | cpu, handle, shmobj); |
852c2936 MD |
236 | if (ret) |
237 | return ret; | |
238 | ||
1d498196 MD |
239 | align_shm(shmobj, __alignof__(struct commit_counters_hot)); |
240 | set_shmp(buf->commit_hot, | |
241 | zalloc_shm(shmobj, | |
242 | sizeof(struct commit_counters_hot) * chan->backend.num_subbuf)); | |
243 | if (!shmp(handle, buf->commit_hot)) { | |
852c2936 MD |
244 | ret = -ENOMEM; |
245 | goto free_chanbuf; | |
246 | } | |
247 | ||
1d498196 MD |
248 | align_shm(shmobj, __alignof__(struct commit_counters_cold)); |
249 | set_shmp(buf->commit_cold, | |
250 | zalloc_shm(shmobj, | |
251 | sizeof(struct commit_counters_cold) * chan->backend.num_subbuf)); | |
252 | if (!shmp(handle, buf->commit_cold)) { | |
852c2936 MD |
253 | ret = -ENOMEM; |
254 | goto free_commit; | |
255 | } | |
256 | ||
852c2936 MD |
257 | /* |
258 | * Write the subbuffer header for first subbuffer so we know the total | |
259 | * duration of data gathering. | |
260 | */ | |
261 | subbuf_header_size = config->cb.subbuffer_header_size(); | |
262 | v_set(config, &buf->offset, subbuf_header_size); | |
4746ae29 | 263 | subbuffer_id_clear_noref(config, &shmp_index(handle, buf->backend.buf_wsb, 0)->id); |
1d498196 MD |
264 | tsc = config->cb.ring_buffer_clock_read(shmp(handle, buf->backend.chan)); |
265 | config->cb.buffer_begin(buf, tsc, 0, handle); | |
4746ae29 | 266 | v_add(config, subbuf_header_size, &shmp_index(handle, buf->commit_hot, 0)->cc); |
852c2936 MD |
267 | |
268 | if (config->cb.buffer_create) { | |
1d498196 | 269 | ret = config->cb.buffer_create(buf, priv, cpu, chanb->name, handle); |
852c2936 MD |
270 | if (ret) |
271 | goto free_init; | |
272 | } | |
852c2936 | 273 | buf->backend.allocated = 1; |
852c2936 MD |
274 | return 0; |
275 | ||
276 | /* Error handling */ | |
277 | free_init: | |
a6352fd4 | 278 | /* commit_cold will be freed by shm teardown */ |
852c2936 | 279 | free_commit: |
a6352fd4 | 280 | /* commit_hot will be freed by shm teardown */ |
852c2936 | 281 | free_chanbuf: |
852c2936 MD |
282 | return ret; |
283 | } | |
284 | ||
03d2d293 MD |
285 | static |
286 | void lib_ring_buffer_channel_switch_timer(int sig, siginfo_t *si, void *uc) | |
852c2936 | 287 | { |
03d2d293 MD |
288 | const struct lttng_ust_lib_ring_buffer_config *config; |
289 | struct lttng_ust_shm_handle *handle; | |
290 | struct channel *chan; | |
291 | int cpu; | |
292 | ||
293 | assert(CMM_LOAD_SHARED(timer_signal.tid) == pthread_self()); | |
294 | ||
295 | chan = si->si_value.sival_ptr; | |
296 | handle = chan->handle; | |
297 | config = &chan->backend.config; | |
852c2936 | 298 | |
34a91bdb | 299 | DBG("Switch timer for channel %p\n", chan); |
03d2d293 | 300 | |
4dcd7e80 MD |
301 | /* |
302 | * Only flush buffers periodically if readers are active. | |
303 | */ | |
cb7378b3 | 304 | pthread_mutex_lock(&wakeup_fd_mutex); |
03d2d293 MD |
305 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { |
306 | for_each_possible_cpu(cpu) { | |
307 | struct lttng_ust_lib_ring_buffer *buf = | |
308 | shmp(handle, chan->backend.buf[cpu].shmp); | |
f680d83c MD |
309 | |
310 | if (!buf) | |
311 | abort(); | |
4dcd7e80 MD |
312 | if (uatomic_read(&buf->active_readers)) |
313 | lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE, | |
314 | chan->handle); | |
03d2d293 MD |
315 | } |
316 | } else { | |
317 | struct lttng_ust_lib_ring_buffer *buf = | |
318 | shmp(handle, chan->backend.buf[0].shmp); | |
319 | ||
f680d83c MD |
320 | if (!buf) |
321 | abort(); | |
34a91bdb MD |
322 | if (uatomic_read(&buf->active_readers)) |
323 | lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE, | |
324 | chan->handle); | |
325 | } | |
326 | pthread_mutex_unlock(&wakeup_fd_mutex); | |
327 | return; | |
328 | } | |
329 | ||
330 | static | |
331 | void lib_ring_buffer_channel_do_read(struct channel *chan) | |
332 | { | |
333 | const struct lttng_ust_lib_ring_buffer_config *config; | |
334 | struct lttng_ust_shm_handle *handle; | |
335 | int cpu; | |
336 | ||
337 | handle = chan->handle; | |
338 | config = &chan->backend.config; | |
339 | ||
340 | /* | |
341 | * Only flush buffers periodically if readers are active. | |
342 | */ | |
343 | pthread_mutex_lock(&wakeup_fd_mutex); | |
344 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { | |
345 | for_each_possible_cpu(cpu) { | |
346 | struct lttng_ust_lib_ring_buffer *buf = | |
347 | shmp(handle, chan->backend.buf[cpu].shmp); | |
348 | ||
f680d83c MD |
349 | if (!buf) |
350 | abort(); | |
34a91bdb MD |
351 | if (uatomic_read(&buf->active_readers) |
352 | && lib_ring_buffer_poll_deliver(config, buf, | |
353 | chan, handle)) { | |
354 | lib_ring_buffer_wakeup(buf, handle); | |
355 | } | |
356 | } | |
357 | } else { | |
358 | struct lttng_ust_lib_ring_buffer *buf = | |
359 | shmp(handle, chan->backend.buf[0].shmp); | |
360 | ||
f680d83c MD |
361 | if (!buf) |
362 | abort(); | |
34a91bdb MD |
363 | if (uatomic_read(&buf->active_readers) |
364 | && lib_ring_buffer_poll_deliver(config, buf, | |
365 | chan, handle)) { | |
366 | lib_ring_buffer_wakeup(buf, handle); | |
367 | } | |
03d2d293 | 368 | } |
cb7378b3 | 369 | pthread_mutex_unlock(&wakeup_fd_mutex); |
34a91bdb MD |
370 | } |
371 | ||
372 | static | |
373 | void lib_ring_buffer_channel_read_timer(int sig, siginfo_t *si, void *uc) | |
374 | { | |
375 | struct channel *chan; | |
376 | ||
377 | assert(CMM_LOAD_SHARED(timer_signal.tid) == pthread_self()); | |
378 | chan = si->si_value.sival_ptr; | |
379 | DBG("Read timer for channel %p\n", chan); | |
380 | lib_ring_buffer_channel_do_read(chan); | |
03d2d293 MD |
381 | return; |
382 | } | |
383 | ||
384 | static | |
385 | void rb_setmask(sigset_t *mask) | |
386 | { | |
387 | int ret; | |
388 | ||
389 | ret = sigemptyset(mask); | |
390 | if (ret) { | |
391 | PERROR("sigemptyset"); | |
392 | } | |
34a91bdb MD |
393 | ret = sigaddset(mask, LTTNG_UST_RB_SIG_FLUSH); |
394 | if (ret) { | |
395 | PERROR("sigaddset"); | |
396 | } | |
397 | ret = sigaddset(mask, LTTNG_UST_RB_SIG_READ); | |
03d2d293 MD |
398 | if (ret) { |
399 | PERROR("sigaddset"); | |
400 | } | |
401 | ret = sigaddset(mask, LTTNG_UST_RB_SIG_TEARDOWN); | |
402 | if (ret) { | |
403 | PERROR("sigaddset"); | |
404 | } | |
405 | } | |
406 | ||
407 | static | |
408 | void *sig_thread(void *arg) | |
409 | { | |
410 | sigset_t mask; | |
411 | siginfo_t info; | |
412 | int signr; | |
413 | ||
414 | /* Only self thread will receive signal mask. */ | |
415 | rb_setmask(&mask); | |
416 | CMM_STORE_SHARED(timer_signal.tid, pthread_self()); | |
417 | ||
418 | for (;;) { | |
419 | signr = sigwaitinfo(&mask, &info); | |
420 | if (signr == -1) { | |
34a91bdb MD |
421 | if (errno != EINTR) |
422 | PERROR("sigwaitinfo"); | |
03d2d293 MD |
423 | continue; |
424 | } | |
34a91bdb | 425 | if (signr == LTTNG_UST_RB_SIG_FLUSH) { |
03d2d293 MD |
426 | lib_ring_buffer_channel_switch_timer(info.si_signo, |
427 | &info, NULL); | |
34a91bdb MD |
428 | } else if (signr == LTTNG_UST_RB_SIG_READ) { |
429 | lib_ring_buffer_channel_read_timer(info.si_signo, | |
430 | &info, NULL); | |
03d2d293 MD |
431 | } else if (signr == LTTNG_UST_RB_SIG_TEARDOWN) { |
432 | cmm_smp_mb(); | |
433 | CMM_STORE_SHARED(timer_signal.qs_done, 1); | |
434 | cmm_smp_mb(); | |
435 | } else { | |
436 | ERR("Unexptected signal %d\n", info.si_signo); | |
437 | } | |
438 | } | |
439 | return NULL; | |
440 | } | |
441 | ||
442 | /* | |
03d2d293 MD |
443 | * Ensure only a single thread listens on the timer signal. |
444 | */ | |
445 | static | |
446 | void lib_ring_buffer_setup_timer_thread(void) | |
447 | { | |
448 | pthread_t thread; | |
449 | int ret; | |
450 | ||
64bf51a6 | 451 | pthread_mutex_lock(&timer_signal.lock); |
03d2d293 | 452 | if (timer_signal.setup_done) |
64bf51a6 | 453 | goto end; |
03d2d293 MD |
454 | |
455 | ret = pthread_create(&thread, NULL, &sig_thread, NULL); | |
456 | if (ret) { | |
457 | errno = ret; | |
458 | PERROR("pthread_create"); | |
459 | } | |
460 | ret = pthread_detach(thread); | |
461 | if (ret) { | |
462 | errno = ret; | |
463 | PERROR("pthread_detach"); | |
464 | } | |
465 | timer_signal.setup_done = 1; | |
64bf51a6 MD |
466 | end: |
467 | pthread_mutex_unlock(&timer_signal.lock); | |
852c2936 MD |
468 | } |
469 | ||
03d2d293 | 470 | /* |
64bf51a6 | 471 | * Wait for signal-handling thread quiescent state. |
03d2d293 | 472 | */ |
64bf51a6 MD |
473 | static |
474 | void lib_ring_buffer_wait_signal_thread_qs(unsigned int signr) | |
475 | { | |
476 | sigset_t pending_set; | |
477 | int ret; | |
478 | ||
479 | /* | |
480 | * We need to be the only thread interacting with the thread | |
481 | * that manages signals for teardown synchronization. | |
482 | */ | |
483 | pthread_mutex_lock(&timer_signal.lock); | |
484 | ||
485 | /* | |
486 | * Ensure we don't have any signal queued for this channel. | |
487 | */ | |
488 | for (;;) { | |
489 | ret = sigemptyset(&pending_set); | |
490 | if (ret == -1) { | |
491 | PERROR("sigemptyset"); | |
492 | } | |
493 | ret = sigpending(&pending_set); | |
494 | if (ret == -1) { | |
495 | PERROR("sigpending"); | |
496 | } | |
497 | if (!sigismember(&pending_set, signr)) | |
498 | break; | |
499 | caa_cpu_relax(); | |
500 | } | |
501 | ||
502 | /* | |
503 | * From this point, no new signal handler will be fired that | |
504 | * would try to access "chan". However, we still need to wait | |
505 | * for any currently executing handler to complete. | |
506 | */ | |
507 | cmm_smp_mb(); | |
508 | CMM_STORE_SHARED(timer_signal.qs_done, 0); | |
509 | cmm_smp_mb(); | |
510 | ||
511 | /* | |
512 | * Kill with LTTNG_UST_RB_SIG_TEARDOWN, so signal management | |
513 | * thread wakes up. | |
514 | */ | |
515 | kill(getpid(), LTTNG_UST_RB_SIG_TEARDOWN); | |
516 | ||
517 | while (!CMM_LOAD_SHARED(timer_signal.qs_done)) | |
518 | caa_cpu_relax(); | |
519 | cmm_smp_mb(); | |
520 | ||
521 | pthread_mutex_unlock(&timer_signal.lock); | |
522 | } | |
523 | ||
03d2d293 MD |
524 | static |
525 | void lib_ring_buffer_channel_switch_timer_start(struct channel *chan) | |
852c2936 | 526 | { |
03d2d293 MD |
527 | struct sigevent sev; |
528 | struct itimerspec its; | |
529 | int ret; | |
852c2936 | 530 | |
03d2d293 | 531 | if (!chan->switch_timer_interval || chan->switch_timer_enabled) |
852c2936 MD |
532 | return; |
533 | ||
03d2d293 MD |
534 | chan->switch_timer_enabled = 1; |
535 | ||
536 | lib_ring_buffer_setup_timer_thread(); | |
537 | ||
538 | sev.sigev_notify = SIGEV_SIGNAL; | |
34a91bdb | 539 | sev.sigev_signo = LTTNG_UST_RB_SIG_FLUSH; |
03d2d293 MD |
540 | sev.sigev_value.sival_ptr = chan; |
541 | ret = timer_create(CLOCKID, &sev, &chan->switch_timer); | |
542 | if (ret == -1) { | |
543 | PERROR("timer_create"); | |
544 | } | |
545 | ||
546 | its.it_value.tv_sec = chan->switch_timer_interval / 1000000; | |
547 | its.it_value.tv_nsec = chan->switch_timer_interval % 1000000; | |
548 | its.it_interval.tv_sec = its.it_value.tv_sec; | |
549 | its.it_interval.tv_nsec = its.it_value.tv_nsec; | |
550 | ||
551 | ret = timer_settime(chan->switch_timer, 0, &its, NULL); | |
552 | if (ret == -1) { | |
553 | PERROR("timer_settime"); | |
554 | } | |
555 | } | |
556 | ||
03d2d293 MD |
557 | static |
558 | void lib_ring_buffer_channel_switch_timer_stop(struct channel *chan) | |
559 | { | |
34a91bdb | 560 | int ret; |
03d2d293 MD |
561 | |
562 | if (!chan->switch_timer_interval || !chan->switch_timer_enabled) | |
563 | return; | |
564 | ||
565 | ret = timer_delete(chan->switch_timer); | |
566 | if (ret == -1) { | |
567 | PERROR("timer_delete"); | |
568 | } | |
569 | ||
64bf51a6 | 570 | lib_ring_buffer_wait_signal_thread_qs(LTTNG_UST_RB_SIG_FLUSH); |
03d2d293 MD |
571 | |
572 | chan->switch_timer = 0; | |
573 | chan->switch_timer_enabled = 0; | |
852c2936 MD |
574 | } |
575 | ||
34a91bdb MD |
576 | static |
577 | void lib_ring_buffer_channel_read_timer_start(struct channel *chan) | |
852c2936 | 578 | { |
4cfec15c | 579 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
34a91bdb MD |
580 | struct sigevent sev; |
581 | struct itimerspec its; | |
582 | int ret; | |
852c2936 | 583 | |
34a91bdb MD |
584 | if (config->wakeup != RING_BUFFER_WAKEUP_BY_TIMER |
585 | || !chan->read_timer_interval || chan->read_timer_enabled) | |
586 | return; | |
852c2936 | 587 | |
34a91bdb | 588 | chan->read_timer_enabled = 1; |
852c2936 | 589 | |
34a91bdb | 590 | lib_ring_buffer_setup_timer_thread(); |
852c2936 | 591 | |
34a91bdb MD |
592 | sev.sigev_notify = SIGEV_SIGNAL; |
593 | sev.sigev_signo = LTTNG_UST_RB_SIG_READ; | |
594 | sev.sigev_value.sival_ptr = chan; | |
595 | ret = timer_create(CLOCKID, &sev, &chan->read_timer); | |
596 | if (ret == -1) { | |
597 | PERROR("timer_create"); | |
598 | } | |
852c2936 | 599 | |
34a91bdb MD |
600 | its.it_value.tv_sec = chan->read_timer_interval / 1000000; |
601 | its.it_value.tv_nsec = chan->read_timer_interval % 1000000; | |
602 | its.it_interval.tv_sec = its.it_value.tv_sec; | |
603 | its.it_interval.tv_nsec = its.it_value.tv_nsec; | |
852c2936 | 604 | |
34a91bdb MD |
605 | ret = timer_settime(chan->read_timer, 0, &its, NULL); |
606 | if (ret == -1) { | |
607 | PERROR("timer_settime"); | |
608 | } | |
852c2936 MD |
609 | } |
610 | ||
34a91bdb MD |
611 | static |
612 | void lib_ring_buffer_channel_read_timer_stop(struct channel *chan) | |
852c2936 | 613 | { |
4cfec15c | 614 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
34a91bdb | 615 | int ret; |
852c2936 MD |
616 | |
617 | if (config->wakeup != RING_BUFFER_WAKEUP_BY_TIMER | |
34a91bdb | 618 | || !chan->read_timer_interval || !chan->read_timer_enabled) |
852c2936 MD |
619 | return; |
620 | ||
34a91bdb MD |
621 | ret = timer_delete(chan->read_timer); |
622 | if (ret == -1) { | |
623 | PERROR("timer_delete"); | |
624 | } | |
625 | ||
852c2936 MD |
626 | /* |
627 | * do one more check to catch data that has been written in the last | |
628 | * timer period. | |
629 | */ | |
34a91bdb MD |
630 | lib_ring_buffer_channel_do_read(chan); |
631 | ||
64bf51a6 | 632 | lib_ring_buffer_wait_signal_thread_qs(LTTNG_UST_RB_SIG_READ); |
34a91bdb MD |
633 | |
634 | chan->read_timer = 0; | |
635 | chan->read_timer_enabled = 0; | |
852c2936 MD |
636 | } |
637 | ||
1d498196 | 638 | static void channel_unregister_notifiers(struct channel *chan, |
38fae1d3 | 639 | struct lttng_ust_shm_handle *handle) |
852c2936 | 640 | { |
03d2d293 | 641 | lib_ring_buffer_channel_switch_timer_stop(chan); |
34a91bdb | 642 | lib_ring_buffer_channel_read_timer_stop(chan); |
852c2936 MD |
643 | } |
644 | ||
009769ca MD |
645 | static void channel_print_errors(struct channel *chan, |
646 | struct lttng_ust_shm_handle *handle) | |
647 | { | |
648 | const struct lttng_ust_lib_ring_buffer_config *config = | |
649 | &chan->backend.config; | |
650 | int cpu; | |
651 | ||
652 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { | |
653 | for_each_possible_cpu(cpu) { | |
654 | struct lttng_ust_lib_ring_buffer *buf = | |
655 | shmp(handle, chan->backend.buf[cpu].shmp); | |
656 | lib_ring_buffer_print_errors(chan, buf, cpu, handle); | |
657 | } | |
658 | } else { | |
659 | struct lttng_ust_lib_ring_buffer *buf = | |
660 | shmp(handle, chan->backend.buf[0].shmp); | |
661 | ||
662 | lib_ring_buffer_print_errors(chan, buf, -1, handle); | |
663 | } | |
664 | } | |
665 | ||
666 | static void channel_free(struct channel *chan, | |
667 | struct lttng_ust_shm_handle *handle) | |
852c2936 | 668 | { |
74d81a6c | 669 | channel_backend_free(&chan->backend, handle); |
431d5cf0 | 670 | /* chan is freed by shm teardown */ |
1d498196 MD |
671 | shm_object_table_destroy(handle->table); |
672 | free(handle); | |
852c2936 MD |
673 | } |
674 | ||
675 | /** | |
676 | * channel_create - Create channel. | |
677 | * @config: ring buffer instance configuration | |
678 | * @name: name of the channel | |
a3f61e7f MD |
679 | * @priv_data: ring buffer client private data area pointer (output) |
680 | * @priv_data_size: length, in bytes, of the private data area. | |
d028eddb | 681 | * @priv_data_init: initialization data for private data. |
852c2936 MD |
682 | * @buf_addr: pointer the the beginning of the preallocated buffer contiguous |
683 | * address mapping. It is used only by RING_BUFFER_STATIC | |
684 | * configuration. It can be set to NULL for other backends. | |
685 | * @subbuf_size: subbuffer size | |
686 | * @num_subbuf: number of subbuffers | |
687 | * @switch_timer_interval: Time interval (in us) to fill sub-buffers with | |
688 | * padding to let readers get those sub-buffers. | |
689 | * Used for live streaming. | |
690 | * @read_timer_interval: Time interval (in us) to wake up pending readers. | |
691 | * | |
692 | * Holds cpu hotplug. | |
693 | * Returns NULL on failure. | |
694 | */ | |
4cfec15c | 695 | struct lttng_ust_shm_handle *channel_create(const struct lttng_ust_lib_ring_buffer_config *config, |
a3f61e7f MD |
696 | const char *name, |
697 | void **priv_data, | |
698 | size_t priv_data_align, | |
699 | size_t priv_data_size, | |
d028eddb | 700 | void *priv_data_init, |
a3f61e7f | 701 | void *buf_addr, size_t subbuf_size, |
852c2936 | 702 | size_t num_subbuf, unsigned int switch_timer_interval, |
74d81a6c | 703 | unsigned int read_timer_interval) |
852c2936 | 704 | { |
24622edc | 705 | int ret; |
a3f61e7f | 706 | size_t shmsize, chansize; |
852c2936 | 707 | struct channel *chan; |
38fae1d3 | 708 | struct lttng_ust_shm_handle *handle; |
1d498196 | 709 | struct shm_object *shmobj; |
74d81a6c MD |
710 | unsigned int nr_streams; |
711 | ||
712 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) | |
713 | nr_streams = num_possible_cpus(); | |
714 | else | |
715 | nr_streams = 1; | |
852c2936 MD |
716 | |
717 | if (lib_ring_buffer_check_config(config, switch_timer_interval, | |
718 | read_timer_interval)) | |
719 | return NULL; | |
720 | ||
38fae1d3 | 721 | handle = zmalloc(sizeof(struct lttng_ust_shm_handle)); |
431d5cf0 MD |
722 | if (!handle) |
723 | return NULL; | |
724 | ||
1d498196 MD |
725 | /* Allocate table for channel + per-cpu buffers */ |
726 | handle->table = shm_object_table_create(1 + num_possible_cpus()); | |
727 | if (!handle->table) | |
728 | goto error_table_alloc; | |
852c2936 | 729 | |
1d498196 MD |
730 | /* Calculate the shm allocation layout */ |
731 | shmsize = sizeof(struct channel); | |
c1fca457 | 732 | shmsize += offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_shmp)); |
74d81a6c | 733 | shmsize += sizeof(struct lttng_ust_lib_ring_buffer_shmp) * nr_streams; |
a3f61e7f | 734 | chansize = shmsize; |
74d81a6c MD |
735 | if (priv_data_align) |
736 | shmsize += offset_align(shmsize, priv_data_align); | |
a3f61e7f | 737 | shmsize += priv_data_size; |
a6352fd4 | 738 | |
74d81a6c MD |
739 | /* Allocate normal memory for channel (not shared) */ |
740 | shmobj = shm_object_table_alloc(handle->table, shmsize, SHM_OBJECT_MEM); | |
b5a14697 MD |
741 | if (!shmobj) |
742 | goto error_append; | |
57773204 | 743 | /* struct channel is at object 0, offset 0 (hardcoded) */ |
a3f61e7f | 744 | set_shmp(handle->chan, zalloc_shm(shmobj, chansize)); |
57773204 MD |
745 | assert(handle->chan._ref.index == 0); |
746 | assert(handle->chan._ref.offset == 0); | |
1d498196 | 747 | chan = shmp(handle, handle->chan); |
a6352fd4 | 748 | if (!chan) |
1d498196 | 749 | goto error_append; |
74d81a6c | 750 | chan->nr_streams = nr_streams; |
a6352fd4 | 751 | |
a3f61e7f MD |
752 | /* space for private data */ |
753 | if (priv_data_size) { | |
754 | DECLARE_SHMP(void, priv_data_alloc); | |
755 | ||
756 | align_shm(shmobj, priv_data_align); | |
757 | chan->priv_data_offset = shmobj->allocated_len; | |
758 | set_shmp(priv_data_alloc, zalloc_shm(shmobj, priv_data_size)); | |
759 | if (!shmp(handle, priv_data_alloc)) | |
760 | goto error_append; | |
761 | *priv_data = channel_get_private(chan); | |
d028eddb | 762 | memcpy(*priv_data, priv_data_init, priv_data_size); |
a3f61e7f MD |
763 | } else { |
764 | chan->priv_data_offset = -1; | |
74d81a6c MD |
765 | if (priv_data) |
766 | *priv_data = NULL; | |
a3f61e7f MD |
767 | } |
768 | ||
769 | ret = channel_backend_init(&chan->backend, name, config, | |
1d498196 | 770 | subbuf_size, num_subbuf, handle); |
852c2936 | 771 | if (ret) |
1d498196 | 772 | goto error_backend_init; |
852c2936 | 773 | |
03d2d293 | 774 | chan->handle = handle; |
852c2936 | 775 | chan->commit_count_mask = (~0UL >> chan->backend.num_subbuf_order); |
852c2936 | 776 | |
34a91bdb MD |
777 | chan->switch_timer_interval = switch_timer_interval; |
778 | chan->read_timer_interval = read_timer_interval; | |
03d2d293 | 779 | lib_ring_buffer_channel_switch_timer_start(chan); |
34a91bdb | 780 | lib_ring_buffer_channel_read_timer_start(chan); |
852c2936 | 781 | |
431d5cf0 | 782 | return handle; |
852c2936 | 783 | |
1d498196 MD |
784 | error_backend_init: |
785 | error_append: | |
786 | shm_object_table_destroy(handle->table); | |
787 | error_table_alloc: | |
431d5cf0 | 788 | free(handle); |
852c2936 MD |
789 | return NULL; |
790 | } | |
852c2936 | 791 | |
74d81a6c | 792 | struct lttng_ust_shm_handle *channel_handle_create(void *data, |
ff0f5728 MD |
793 | uint64_t memory_map_size, |
794 | int wakeup_fd) | |
193183fb | 795 | { |
38fae1d3 | 796 | struct lttng_ust_shm_handle *handle; |
193183fb MD |
797 | struct shm_object *object; |
798 | ||
38fae1d3 | 799 | handle = zmalloc(sizeof(struct lttng_ust_shm_handle)); |
193183fb MD |
800 | if (!handle) |
801 | return NULL; | |
802 | ||
803 | /* Allocate table for channel + per-cpu buffers */ | |
804 | handle->table = shm_object_table_create(1 + num_possible_cpus()); | |
805 | if (!handle->table) | |
806 | goto error_table_alloc; | |
807 | /* Add channel object */ | |
74d81a6c | 808 | object = shm_object_table_append_mem(handle->table, data, |
ff0f5728 | 809 | memory_map_size, wakeup_fd); |
193183fb MD |
810 | if (!object) |
811 | goto error_table_object; | |
57773204 MD |
812 | /* struct channel is at object 0, offset 0 (hardcoded) */ |
813 | handle->chan._ref.index = 0; | |
814 | handle->chan._ref.offset = 0; | |
193183fb MD |
815 | return handle; |
816 | ||
817 | error_table_object: | |
818 | shm_object_table_destroy(handle->table); | |
819 | error_table_alloc: | |
820 | free(handle); | |
821 | return NULL; | |
822 | } | |
823 | ||
38fae1d3 | 824 | int channel_handle_add_stream(struct lttng_ust_shm_handle *handle, |
74d81a6c MD |
825 | int shm_fd, int wakeup_fd, uint32_t stream_nr, |
826 | uint64_t memory_map_size) | |
193183fb MD |
827 | { |
828 | struct shm_object *object; | |
829 | ||
830 | /* Add stream object */ | |
74d81a6c MD |
831 | object = shm_object_table_append_shm(handle->table, |
832 | shm_fd, wakeup_fd, stream_nr, | |
833 | memory_map_size); | |
193183fb | 834 | if (!object) |
74d81a6c | 835 | return -EINVAL; |
193183fb MD |
836 | return 0; |
837 | } | |
838 | ||
74d81a6c MD |
839 | unsigned int channel_handle_get_nr_streams(struct lttng_ust_shm_handle *handle) |
840 | { | |
841 | assert(handle->table); | |
842 | return handle->table->allocated_len - 1; | |
843 | } | |
844 | ||
852c2936 | 845 | static |
74d81a6c | 846 | void channel_release(struct channel *chan, struct lttng_ust_shm_handle *handle) |
852c2936 | 847 | { |
74d81a6c | 848 | channel_free(chan, handle); |
852c2936 MD |
849 | } |
850 | ||
851 | /** | |
852 | * channel_destroy - Finalize, wait for q.s. and destroy channel. | |
853 | * @chan: channel to destroy | |
854 | * | |
855 | * Holds cpu hotplug. | |
431d5cf0 MD |
856 | * Call "destroy" callback, finalize channels, decrement the channel |
857 | * reference count. Note that when readers have completed data | |
858 | * consumption of finalized channels, get_subbuf() will return -ENODATA. | |
a3f61e7f | 859 | * They should release their handle at that point. |
852c2936 | 860 | */ |
a3f61e7f | 861 | void channel_destroy(struct channel *chan, struct lttng_ust_shm_handle *handle, |
74d81a6c | 862 | int consumer) |
852c2936 | 863 | { |
74d81a6c MD |
864 | if (consumer) { |
865 | /* | |
866 | * Note: the consumer takes care of finalizing and | |
867 | * switching the buffers. | |
868 | */ | |
869 | channel_unregister_notifiers(chan, handle); | |
3d0ef9f6 MD |
870 | /* |
871 | * The consumer prints errors. | |
872 | */ | |
873 | channel_print_errors(chan, handle); | |
824f40b8 MD |
874 | } |
875 | ||
431d5cf0 MD |
876 | /* |
877 | * sessiond/consumer are keeping a reference on the shm file | |
878 | * descriptor directly. No need to refcount. | |
879 | */ | |
74d81a6c | 880 | channel_release(chan, handle); |
a3f61e7f | 881 | return; |
852c2936 | 882 | } |
852c2936 | 883 | |
4cfec15c MD |
884 | struct lttng_ust_lib_ring_buffer *channel_get_ring_buffer( |
885 | const struct lttng_ust_lib_ring_buffer_config *config, | |
1d498196 | 886 | struct channel *chan, int cpu, |
38fae1d3 | 887 | struct lttng_ust_shm_handle *handle, |
74d81a6c MD |
888 | int *shm_fd, int *wait_fd, |
889 | int *wakeup_fd, | |
890 | uint64_t *memory_map_size) | |
852c2936 | 891 | { |
381c0f1e MD |
892 | struct shm_ref *ref; |
893 | ||
894 | if (config->alloc == RING_BUFFER_ALLOC_GLOBAL) { | |
74d81a6c | 895 | cpu = 0; |
381c0f1e | 896 | } else { |
e095d803 MD |
897 | if (cpu >= num_possible_cpus()) |
898 | return NULL; | |
381c0f1e | 899 | } |
74d81a6c MD |
900 | ref = &chan->backend.buf[cpu].shmp._ref; |
901 | *shm_fd = shm_get_shm_fd(handle, ref); | |
902 | *wait_fd = shm_get_wait_fd(handle, ref); | |
903 | *wakeup_fd = shm_get_wakeup_fd(handle, ref); | |
904 | if (shm_get_shm_size(handle, ref, memory_map_size)) | |
905 | return NULL; | |
906 | return shmp(handle, chan->backend.buf[cpu].shmp); | |
852c2936 | 907 | } |
852c2936 | 908 | |
ff0f5728 MD |
909 | int ring_buffer_channel_close_wait_fd(const struct lttng_ust_lib_ring_buffer_config *config, |
910 | struct channel *chan, | |
911 | struct lttng_ust_shm_handle *handle) | |
912 | { | |
913 | struct shm_ref *ref; | |
914 | ||
915 | ref = &handle->chan._ref; | |
916 | return shm_close_wait_fd(handle, ref); | |
917 | } | |
918 | ||
919 | int ring_buffer_channel_close_wakeup_fd(const struct lttng_ust_lib_ring_buffer_config *config, | |
920 | struct channel *chan, | |
921 | struct lttng_ust_shm_handle *handle) | |
922 | { | |
923 | struct shm_ref *ref; | |
924 | ||
925 | ref = &handle->chan._ref; | |
926 | return shm_close_wakeup_fd(handle, ref); | |
927 | } | |
928 | ||
929 | int ring_buffer_stream_close_wait_fd(const struct lttng_ust_lib_ring_buffer_config *config, | |
74d81a6c MD |
930 | struct channel *chan, |
931 | struct lttng_ust_shm_handle *handle, | |
932 | int cpu) | |
852c2936 | 933 | { |
74d81a6c MD |
934 | struct shm_ref *ref; |
935 | ||
936 | if (config->alloc == RING_BUFFER_ALLOC_GLOBAL) { | |
937 | cpu = 0; | |
938 | } else { | |
939 | if (cpu >= num_possible_cpus()) | |
940 | return -EINVAL; | |
824f40b8 | 941 | } |
74d81a6c MD |
942 | ref = &chan->backend.buf[cpu].shmp._ref; |
943 | return shm_close_wait_fd(handle, ref); | |
944 | } | |
945 | ||
ff0f5728 | 946 | int ring_buffer_stream_close_wakeup_fd(const struct lttng_ust_lib_ring_buffer_config *config, |
74d81a6c MD |
947 | struct channel *chan, |
948 | struct lttng_ust_shm_handle *handle, | |
949 | int cpu) | |
950 | { | |
951 | struct shm_ref *ref; | |
cb7378b3 | 952 | int ret; |
74d81a6c MD |
953 | |
954 | if (config->alloc == RING_BUFFER_ALLOC_GLOBAL) { | |
955 | cpu = 0; | |
956 | } else { | |
957 | if (cpu >= num_possible_cpus()) | |
958 | return -EINVAL; | |
959 | } | |
960 | ref = &chan->backend.buf[cpu].shmp._ref; | |
cb7378b3 MD |
961 | pthread_mutex_lock(&wakeup_fd_mutex); |
962 | ret = shm_close_wakeup_fd(handle, ref); | |
963 | pthread_mutex_unlock(&wakeup_fd_mutex); | |
964 | return ret; | |
74d81a6c MD |
965 | } |
966 | ||
967 | int lib_ring_buffer_open_read(struct lttng_ust_lib_ring_buffer *buf, | |
968 | struct lttng_ust_shm_handle *handle) | |
969 | { | |
a6352fd4 | 970 | if (uatomic_cmpxchg(&buf->active_readers, 0, 1) != 0) |
852c2936 | 971 | return -EBUSY; |
a6352fd4 | 972 | cmm_smp_mb(); |
852c2936 MD |
973 | return 0; |
974 | } | |
852c2936 | 975 | |
4cfec15c | 976 | void lib_ring_buffer_release_read(struct lttng_ust_lib_ring_buffer *buf, |
74d81a6c | 977 | struct lttng_ust_shm_handle *handle) |
852c2936 | 978 | { |
1d498196 | 979 | struct channel *chan = shmp(handle, buf->backend.chan); |
852c2936 | 980 | |
a6352fd4 MD |
981 | CHAN_WARN_ON(chan, uatomic_read(&buf->active_readers) != 1); |
982 | cmm_smp_mb(); | |
983 | uatomic_dec(&buf->active_readers); | |
852c2936 MD |
984 | } |
985 | ||
986 | /** | |
987 | * lib_ring_buffer_snapshot - save subbuffer position snapshot (for read) | |
988 | * @buf: ring buffer | |
989 | * @consumed: consumed count indicating the position where to read | |
990 | * @produced: produced count, indicates position when to stop reading | |
991 | * | |
992 | * Returns -ENODATA if buffer is finalized, -EAGAIN if there is currently no | |
993 | * data to read at consumed position, or 0 if the get operation succeeds. | |
852c2936 MD |
994 | */ |
995 | ||
4cfec15c | 996 | int lib_ring_buffer_snapshot(struct lttng_ust_lib_ring_buffer *buf, |
1d498196 | 997 | unsigned long *consumed, unsigned long *produced, |
38fae1d3 | 998 | struct lttng_ust_shm_handle *handle) |
852c2936 | 999 | { |
1d498196 | 1000 | struct channel *chan = shmp(handle, buf->backend.chan); |
4cfec15c | 1001 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
852c2936 MD |
1002 | unsigned long consumed_cur, write_offset; |
1003 | int finalized; | |
1004 | ||
14641deb | 1005 | finalized = CMM_ACCESS_ONCE(buf->finalized); |
852c2936 MD |
1006 | /* |
1007 | * Read finalized before counters. | |
1008 | */ | |
a6352fd4 MD |
1009 | cmm_smp_rmb(); |
1010 | consumed_cur = uatomic_read(&buf->consumed); | |
852c2936 MD |
1011 | /* |
1012 | * No need to issue a memory barrier between consumed count read and | |
1013 | * write offset read, because consumed count can only change | |
1014 | * concurrently in overwrite mode, and we keep a sequence counter | |
1015 | * identifier derived from the write offset to check we are getting | |
1016 | * the same sub-buffer we are expecting (the sub-buffers are atomically | |
1017 | * "tagged" upon writes, tags are checked upon read). | |
1018 | */ | |
1019 | write_offset = v_read(config, &buf->offset); | |
1020 | ||
1021 | /* | |
1022 | * Check that we are not about to read the same subbuffer in | |
1023 | * which the writer head is. | |
1024 | */ | |
1025 | if (subbuf_trunc(write_offset, chan) - subbuf_trunc(consumed_cur, chan) | |
1026 | == 0) | |
1027 | goto nodata; | |
1028 | ||
1029 | *consumed = consumed_cur; | |
1030 | *produced = subbuf_trunc(write_offset, chan); | |
1031 | ||
1032 | return 0; | |
1033 | ||
1034 | nodata: | |
1035 | /* | |
1036 | * The memory barriers __wait_event()/wake_up_interruptible() take care | |
1037 | * of "raw_spin_is_locked" memory ordering. | |
1038 | */ | |
1039 | if (finalized) | |
1040 | return -ENODATA; | |
852c2936 MD |
1041 | else |
1042 | return -EAGAIN; | |
1043 | } | |
852c2936 MD |
1044 | |
1045 | /** | |
d1a996f5 | 1046 | * lib_ring_buffer_move_consumer - move consumed counter forward |
852c2936 MD |
1047 | * @buf: ring buffer |
1048 | * @consumed_new: new consumed count value | |
1049 | */ | |
4cfec15c | 1050 | void lib_ring_buffer_move_consumer(struct lttng_ust_lib_ring_buffer *buf, |
1d498196 | 1051 | unsigned long consumed_new, |
38fae1d3 | 1052 | struct lttng_ust_shm_handle *handle) |
852c2936 | 1053 | { |
4cfec15c | 1054 | struct lttng_ust_lib_ring_buffer_backend *bufb = &buf->backend; |
1d498196 | 1055 | struct channel *chan = shmp(handle, bufb->chan); |
852c2936 MD |
1056 | unsigned long consumed; |
1057 | ||
74d81a6c | 1058 | CHAN_WARN_ON(chan, uatomic_read(&buf->active_readers) != 1); |
852c2936 MD |
1059 | |
1060 | /* | |
1061 | * Only push the consumed value forward. | |
1062 | * If the consumed cmpxchg fails, this is because we have been pushed by | |
1063 | * the writer in flight recorder mode. | |
1064 | */ | |
a6352fd4 | 1065 | consumed = uatomic_read(&buf->consumed); |
852c2936 | 1066 | while ((long) consumed - (long) consumed_new < 0) |
a6352fd4 MD |
1067 | consumed = uatomic_cmpxchg(&buf->consumed, consumed, |
1068 | consumed_new); | |
852c2936 | 1069 | } |
852c2936 MD |
1070 | |
1071 | /** | |
1072 | * lib_ring_buffer_get_subbuf - get exclusive access to subbuffer for reading | |
1073 | * @buf: ring buffer | |
1074 | * @consumed: consumed count indicating the position where to read | |
1075 | * | |
1076 | * Returns -ENODATA if buffer is finalized, -EAGAIN if there is currently no | |
1077 | * data to read at consumed position, or 0 if the get operation succeeds. | |
852c2936 | 1078 | */ |
4cfec15c | 1079 | int lib_ring_buffer_get_subbuf(struct lttng_ust_lib_ring_buffer *buf, |
1d498196 | 1080 | unsigned long consumed, |
38fae1d3 | 1081 | struct lttng_ust_shm_handle *handle) |
852c2936 | 1082 | { |
1d498196 | 1083 | struct channel *chan = shmp(handle, buf->backend.chan); |
4cfec15c | 1084 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
852c2936 | 1085 | unsigned long consumed_cur, consumed_idx, commit_count, write_offset; |
87edc338 | 1086 | int ret, finalized, nr_retry = LTTNG_UST_RING_BUFFER_GET_RETRY; |
852c2936 MD |
1087 | |
1088 | retry: | |
14641deb | 1089 | finalized = CMM_ACCESS_ONCE(buf->finalized); |
852c2936 MD |
1090 | /* |
1091 | * Read finalized before counters. | |
1092 | */ | |
a6352fd4 MD |
1093 | cmm_smp_rmb(); |
1094 | consumed_cur = uatomic_read(&buf->consumed); | |
852c2936 | 1095 | consumed_idx = subbuf_index(consumed, chan); |
4746ae29 | 1096 | commit_count = v_read(config, &shmp_index(handle, buf->commit_cold, consumed_idx)->cc_sb); |
852c2936 MD |
1097 | /* |
1098 | * Make sure we read the commit count before reading the buffer | |
1099 | * data and the write offset. Correct consumed offset ordering | |
1100 | * wrt commit count is insured by the use of cmpxchg to update | |
1101 | * the consumed offset. | |
852c2936 | 1102 | */ |
a6352fd4 MD |
1103 | /* |
1104 | * Local rmb to match the remote wmb to read the commit count | |
1105 | * before the buffer data and the write offset. | |
1106 | */ | |
1107 | cmm_smp_rmb(); | |
852c2936 MD |
1108 | |
1109 | write_offset = v_read(config, &buf->offset); | |
1110 | ||
1111 | /* | |
1112 | * Check that the buffer we are getting is after or at consumed_cur | |
1113 | * position. | |
1114 | */ | |
1115 | if ((long) subbuf_trunc(consumed, chan) | |
1116 | - (long) subbuf_trunc(consumed_cur, chan) < 0) | |
1117 | goto nodata; | |
1118 | ||
1119 | /* | |
1120 | * Check that the subbuffer we are trying to consume has been | |
87edc338 MD |
1121 | * already fully committed. There are a few causes that can make |
1122 | * this unavailability situation occur: | |
1123 | * | |
1124 | * Temporary (short-term) situation: | |
1125 | * - Application is running on a different CPU, between reserve | |
1126 | * and commit ring buffer operations, | |
1127 | * - Application is preempted between reserve and commit ring | |
1128 | * buffer operations, | |
1129 | * | |
1130 | * Long-term situation: | |
1131 | * - Application is stopped (SIGSTOP) between reserve and commit | |
1132 | * ring buffer operations. Could eventually be resumed by | |
1133 | * SIGCONT. | |
1134 | * - Application is killed (SIGTERM, SIGINT, SIGKILL) between | |
1135 | * reserve and commit ring buffer operation. | |
1136 | * | |
1137 | * From a consumer perspective, handling short-term | |
1138 | * unavailability situations is performed by retrying a few | |
1139 | * times after a delay. Handling long-term unavailability | |
1140 | * situations is handled by failing to get the sub-buffer. | |
1141 | * | |
1142 | * In all of those situations, if the application is taking a | |
1143 | * long time to perform its commit after ring buffer space | |
1144 | * reservation, we can end up in a situation where the producer | |
1145 | * will fill the ring buffer and try to write into the same | |
1146 | * sub-buffer again (which has a missing commit). This is | |
1147 | * handled by the producer in the sub-buffer switch handling | |
1148 | * code of the reserve routine by detecting unbalanced | |
1149 | * reserve/commit counters and discarding all further events | |
1150 | * until the situation is resolved in those situations. Two | |
1151 | * scenarios can occur: | |
1152 | * | |
1153 | * 1) The application causing the reserve/commit counters to be | |
1154 | * unbalanced has been terminated. In this situation, all | |
1155 | * further events will be discarded in the buffers, and no | |
1156 | * further buffer data will be readable by the consumer | |
1157 | * daemon. Tearing down the UST tracing session and starting | |
1158 | * anew is a work-around for those situations. Note that this | |
1159 | * only affects per-UID tracing. In per-PID tracing, the | |
1160 | * application vanishes with the termination, and therefore | |
1161 | * no more data needs to be written to the buffers. | |
1162 | * 2) The application causing the unbalance has been delayed for | |
1163 | * a long time, but will eventually try to increment the | |
1164 | * commit counter after eventually writing to the sub-buffer. | |
1165 | * This situation can cause events to be discarded until the | |
1166 | * application resumes its operations. | |
852c2936 MD |
1167 | */ |
1168 | if (((commit_count - chan->backend.subbuf_size) | |
1169 | & chan->commit_count_mask) | |
0bade047 | 1170 | - (buf_trunc(consumed, chan) |
852c2936 | 1171 | >> chan->backend.num_subbuf_order) |
87edc338 MD |
1172 | != 0) { |
1173 | if (nr_retry-- > 0) { | |
1174 | if (nr_retry <= (LTTNG_UST_RING_BUFFER_GET_RETRY >> 1)) | |
1175 | (void) poll(NULL, 0, LTTNG_UST_RING_BUFFER_RETRY_DELAY_MS); | |
1176 | goto retry; | |
1177 | } else { | |
1178 | goto nodata; | |
1179 | } | |
1180 | } | |
852c2936 MD |
1181 | |
1182 | /* | |
1183 | * Check that we are not about to read the same subbuffer in | |
1184 | * which the writer head is. | |
1185 | */ | |
0bade047 | 1186 | if (subbuf_trunc(write_offset, chan) - subbuf_trunc(consumed, chan) |
852c2936 MD |
1187 | == 0) |
1188 | goto nodata; | |
1189 | ||
1190 | /* | |
1191 | * Failure to get the subbuffer causes a busy-loop retry without going | |
1192 | * to a wait queue. These are caused by short-lived race windows where | |
1193 | * the writer is getting access to a subbuffer we were trying to get | |
1194 | * access to. Also checks that the "consumed" buffer count we are | |
1195 | * looking for matches the one contained in the subbuffer id. | |
87edc338 MD |
1196 | * |
1197 | * The short-lived race window described here can be affected by | |
1198 | * application signals and preemption, thus requiring to bound | |
1199 | * the loop to a maximum number of retry. | |
852c2936 MD |
1200 | */ |
1201 | ret = update_read_sb_index(config, &buf->backend, &chan->backend, | |
1d498196 MD |
1202 | consumed_idx, buf_trunc_val(consumed, chan), |
1203 | handle); | |
87edc338 MD |
1204 | if (ret) { |
1205 | if (nr_retry-- > 0) { | |
1206 | if (nr_retry <= (LTTNG_UST_RING_BUFFER_GET_RETRY >> 1)) | |
1207 | (void) poll(NULL, 0, LTTNG_UST_RING_BUFFER_RETRY_DELAY_MS); | |
1208 | goto retry; | |
1209 | } else { | |
1210 | goto nodata; | |
1211 | } | |
1212 | } | |
852c2936 MD |
1213 | subbuffer_id_clear_noref(config, &buf->backend.buf_rsb.id); |
1214 | ||
1215 | buf->get_subbuf_consumed = consumed; | |
1216 | buf->get_subbuf = 1; | |
1217 | ||
1218 | return 0; | |
1219 | ||
1220 | nodata: | |
1221 | /* | |
1222 | * The memory barriers __wait_event()/wake_up_interruptible() take care | |
1223 | * of "raw_spin_is_locked" memory ordering. | |
1224 | */ | |
1225 | if (finalized) | |
1226 | return -ENODATA; | |
852c2936 MD |
1227 | else |
1228 | return -EAGAIN; | |
1229 | } | |
852c2936 MD |
1230 | |
1231 | /** | |
1232 | * lib_ring_buffer_put_subbuf - release exclusive subbuffer access | |
1233 | * @buf: ring buffer | |
1234 | */ | |
4cfec15c | 1235 | void lib_ring_buffer_put_subbuf(struct lttng_ust_lib_ring_buffer *buf, |
38fae1d3 | 1236 | struct lttng_ust_shm_handle *handle) |
852c2936 | 1237 | { |
4cfec15c | 1238 | struct lttng_ust_lib_ring_buffer_backend *bufb = &buf->backend; |
1d498196 | 1239 | struct channel *chan = shmp(handle, bufb->chan); |
4cfec15c | 1240 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
852c2936 MD |
1241 | unsigned long read_sb_bindex, consumed_idx, consumed; |
1242 | ||
74d81a6c | 1243 | CHAN_WARN_ON(chan, uatomic_read(&buf->active_readers) != 1); |
852c2936 MD |
1244 | |
1245 | if (!buf->get_subbuf) { | |
1246 | /* | |
1247 | * Reader puts a subbuffer it did not get. | |
1248 | */ | |
1249 | CHAN_WARN_ON(chan, 1); | |
1250 | return; | |
1251 | } | |
1252 | consumed = buf->get_subbuf_consumed; | |
1253 | buf->get_subbuf = 0; | |
1254 | ||
1255 | /* | |
1256 | * Clear the records_unread counter. (overruns counter) | |
1257 | * Can still be non-zero if a file reader simply grabbed the data | |
1258 | * without using iterators. | |
1259 | * Can be below zero if an iterator is used on a snapshot more than | |
1260 | * once. | |
1261 | */ | |
1262 | read_sb_bindex = subbuffer_id_get_index(config, bufb->buf_rsb.id); | |
1263 | v_add(config, v_read(config, | |
4746ae29 | 1264 | &shmp(handle, shmp_index(handle, bufb->array, read_sb_bindex)->shmp)->records_unread), |
852c2936 | 1265 | &bufb->records_read); |
4746ae29 | 1266 | v_set(config, &shmp(handle, shmp_index(handle, bufb->array, read_sb_bindex)->shmp)->records_unread, 0); |
852c2936 MD |
1267 | CHAN_WARN_ON(chan, config->mode == RING_BUFFER_OVERWRITE |
1268 | && subbuffer_id_is_noref(config, bufb->buf_rsb.id)); | |
1269 | subbuffer_id_set_noref(config, &bufb->buf_rsb.id); | |
1270 | ||
1271 | /* | |
1272 | * Exchange the reader subbuffer with the one we put in its place in the | |
1273 | * writer subbuffer table. Expect the original consumed count. If | |
1274 | * update_read_sb_index fails, this is because the writer updated the | |
1275 | * subbuffer concurrently. We should therefore keep the subbuffer we | |
1276 | * currently have: it has become invalid to try reading this sub-buffer | |
1277 | * consumed count value anyway. | |
1278 | */ | |
1279 | consumed_idx = subbuf_index(consumed, chan); | |
1280 | update_read_sb_index(config, &buf->backend, &chan->backend, | |
1d498196 MD |
1281 | consumed_idx, buf_trunc_val(consumed, chan), |
1282 | handle); | |
852c2936 MD |
1283 | /* |
1284 | * update_read_sb_index return value ignored. Don't exchange sub-buffer | |
1285 | * if the writer concurrently updated it. | |
1286 | */ | |
1287 | } | |
852c2936 MD |
1288 | |
1289 | /* | |
1290 | * cons_offset is an iterator on all subbuffer offsets between the reader | |
1291 | * position and the writer position. (inclusive) | |
1292 | */ | |
1293 | static | |
4cfec15c | 1294 | void lib_ring_buffer_print_subbuffer_errors(struct lttng_ust_lib_ring_buffer *buf, |
852c2936 MD |
1295 | struct channel *chan, |
1296 | unsigned long cons_offset, | |
1d498196 | 1297 | int cpu, |
38fae1d3 | 1298 | struct lttng_ust_shm_handle *handle) |
852c2936 | 1299 | { |
4cfec15c | 1300 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
852c2936 MD |
1301 | unsigned long cons_idx, commit_count, commit_count_sb; |
1302 | ||
1303 | cons_idx = subbuf_index(cons_offset, chan); | |
4746ae29 MD |
1304 | commit_count = v_read(config, &shmp_index(handle, buf->commit_hot, cons_idx)->cc); |
1305 | commit_count_sb = v_read(config, &shmp_index(handle, buf->commit_cold, cons_idx)->cc_sb); | |
852c2936 MD |
1306 | |
1307 | if (subbuf_offset(commit_count, chan) != 0) | |
4d3c9523 | 1308 | DBG("ring buffer %s, cpu %d: " |
852c2936 MD |
1309 | "commit count in subbuffer %lu,\n" |
1310 | "expecting multiples of %lu bytes\n" | |
1311 | " [ %lu bytes committed, %lu bytes reader-visible ]\n", | |
1312 | chan->backend.name, cpu, cons_idx, | |
1313 | chan->backend.subbuf_size, | |
1314 | commit_count, commit_count_sb); | |
1315 | ||
4d3c9523 | 1316 | DBG("ring buffer: %s, cpu %d: %lu bytes committed\n", |
852c2936 MD |
1317 | chan->backend.name, cpu, commit_count); |
1318 | } | |
1319 | ||
1320 | static | |
4cfec15c | 1321 | void lib_ring_buffer_print_buffer_errors(struct lttng_ust_lib_ring_buffer *buf, |
852c2936 | 1322 | struct channel *chan, |
1d498196 | 1323 | void *priv, int cpu, |
38fae1d3 | 1324 | struct lttng_ust_shm_handle *handle) |
852c2936 | 1325 | { |
4cfec15c | 1326 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
852c2936 MD |
1327 | unsigned long write_offset, cons_offset; |
1328 | ||
852c2936 MD |
1329 | /* |
1330 | * No need to order commit_count, write_offset and cons_offset reads | |
1331 | * because we execute at teardown when no more writer nor reader | |
1332 | * references are left. | |
1333 | */ | |
1334 | write_offset = v_read(config, &buf->offset); | |
a6352fd4 | 1335 | cons_offset = uatomic_read(&buf->consumed); |
852c2936 | 1336 | if (write_offset != cons_offset) |
4d3c9523 | 1337 | DBG("ring buffer %s, cpu %d: " |
852c2936 MD |
1338 | "non-consumed data\n" |
1339 | " [ %lu bytes written, %lu bytes read ]\n", | |
1340 | chan->backend.name, cpu, write_offset, cons_offset); | |
1341 | ||
a6352fd4 | 1342 | for (cons_offset = uatomic_read(&buf->consumed); |
852c2936 MD |
1343 | (long) (subbuf_trunc((unsigned long) v_read(config, &buf->offset), |
1344 | chan) | |
1345 | - cons_offset) > 0; | |
1346 | cons_offset = subbuf_align(cons_offset, chan)) | |
1347 | lib_ring_buffer_print_subbuffer_errors(buf, chan, cons_offset, | |
1d498196 | 1348 | cpu, handle); |
852c2936 MD |
1349 | } |
1350 | ||
1351 | static | |
1352 | void lib_ring_buffer_print_errors(struct channel *chan, | |
009769ca MD |
1353 | struct lttng_ust_lib_ring_buffer *buf, int cpu, |
1354 | struct lttng_ust_shm_handle *handle) | |
852c2936 | 1355 | { |
4cfec15c | 1356 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
a3f61e7f | 1357 | void *priv = channel_get_private(chan); |
852c2936 | 1358 | |
a1360615 MD |
1359 | if (!strcmp(chan->backend.name, "relay-metadata-mmap")) { |
1360 | DBG("ring buffer %s: %lu records written, " | |
1361 | "%lu records overrun\n", | |
1362 | chan->backend.name, | |
1363 | v_read(config, &buf->records_count), | |
1364 | v_read(config, &buf->records_overrun)); | |
1365 | } else { | |
1366 | DBG("ring buffer %s, cpu %d: %lu records written, " | |
1367 | "%lu records overrun\n", | |
1368 | chan->backend.name, cpu, | |
1369 | v_read(config, &buf->records_count), | |
1370 | v_read(config, &buf->records_overrun)); | |
1371 | ||
1372 | if (v_read(config, &buf->records_lost_full) | |
1373 | || v_read(config, &buf->records_lost_wrap) | |
1374 | || v_read(config, &buf->records_lost_big)) | |
1375 | DBG("ring buffer %s, cpu %d: records were lost. Caused by:\n" | |
1376 | " [ %lu buffer full, %lu nest buffer wrap-around, " | |
1377 | "%lu event too big ]\n", | |
1378 | chan->backend.name, cpu, | |
1379 | v_read(config, &buf->records_lost_full), | |
1380 | v_read(config, &buf->records_lost_wrap), | |
1381 | v_read(config, &buf->records_lost_big)); | |
1382 | } | |
1d498196 | 1383 | lib_ring_buffer_print_buffer_errors(buf, chan, priv, cpu, handle); |
852c2936 MD |
1384 | } |
1385 | ||
1386 | /* | |
1387 | * lib_ring_buffer_switch_old_start: Populate old subbuffer header. | |
1388 | * | |
1389 | * Only executed when the buffer is finalized, in SWITCH_FLUSH. | |
1390 | */ | |
1391 | static | |
4cfec15c | 1392 | void lib_ring_buffer_switch_old_start(struct lttng_ust_lib_ring_buffer *buf, |
852c2936 MD |
1393 | struct channel *chan, |
1394 | struct switch_offsets *offsets, | |
2fed87ae | 1395 | uint64_t tsc, |
38fae1d3 | 1396 | struct lttng_ust_shm_handle *handle) |
852c2936 | 1397 | { |
4cfec15c | 1398 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
852c2936 MD |
1399 | unsigned long oldidx = subbuf_index(offsets->old, chan); |
1400 | unsigned long commit_count; | |
1401 | ||
1d498196 | 1402 | config->cb.buffer_begin(buf, tsc, oldidx, handle); |
852c2936 MD |
1403 | |
1404 | /* | |
1405 | * Order all writes to buffer before the commit count update that will | |
1406 | * determine that the subbuffer is full. | |
1407 | */ | |
a6352fd4 | 1408 | cmm_smp_wmb(); |
852c2936 | 1409 | v_add(config, config->cb.subbuffer_header_size(), |
4746ae29 MD |
1410 | &shmp_index(handle, buf->commit_hot, oldidx)->cc); |
1411 | commit_count = v_read(config, &shmp_index(handle, buf->commit_hot, oldidx)->cc); | |
852c2936 MD |
1412 | /* Check if the written buffer has to be delivered */ |
1413 | lib_ring_buffer_check_deliver(config, buf, chan, offsets->old, | |
1b7b0501 | 1414 | commit_count, oldidx, handle, tsc); |
852c2936 | 1415 | lib_ring_buffer_write_commit_counter(config, buf, chan, oldidx, |
80249235 MD |
1416 | offsets->old + config->cb.subbuffer_header_size(), |
1417 | commit_count, handle); | |
852c2936 MD |
1418 | } |
1419 | ||
1420 | /* | |
1421 | * lib_ring_buffer_switch_old_end: switch old subbuffer | |
1422 | * | |
1423 | * Note : offset_old should never be 0 here. It is ok, because we never perform | |
1424 | * buffer switch on an empty subbuffer in SWITCH_ACTIVE mode. The caller | |
1425 | * increments the offset_old value when doing a SWITCH_FLUSH on an empty | |
1426 | * subbuffer. | |
1427 | */ | |
1428 | static | |
4cfec15c | 1429 | void lib_ring_buffer_switch_old_end(struct lttng_ust_lib_ring_buffer *buf, |
852c2936 MD |
1430 | struct channel *chan, |
1431 | struct switch_offsets *offsets, | |
2fed87ae | 1432 | uint64_t tsc, |
38fae1d3 | 1433 | struct lttng_ust_shm_handle *handle) |
852c2936 | 1434 | { |
4cfec15c | 1435 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
852c2936 MD |
1436 | unsigned long oldidx = subbuf_index(offsets->old - 1, chan); |
1437 | unsigned long commit_count, padding_size, data_size; | |
1438 | ||
1439 | data_size = subbuf_offset(offsets->old - 1, chan) + 1; | |
1440 | padding_size = chan->backend.subbuf_size - data_size; | |
1d498196 MD |
1441 | subbuffer_set_data_size(config, &buf->backend, oldidx, data_size, |
1442 | handle); | |
852c2936 MD |
1443 | |
1444 | /* | |
1445 | * Order all writes to buffer before the commit count update that will | |
1446 | * determine that the subbuffer is full. | |
1447 | */ | |
a6352fd4 | 1448 | cmm_smp_wmb(); |
4746ae29 MD |
1449 | v_add(config, padding_size, &shmp_index(handle, buf->commit_hot, oldidx)->cc); |
1450 | commit_count = v_read(config, &shmp_index(handle, buf->commit_hot, oldidx)->cc); | |
852c2936 | 1451 | lib_ring_buffer_check_deliver(config, buf, chan, offsets->old - 1, |
1b7b0501 | 1452 | commit_count, oldidx, handle, tsc); |
852c2936 | 1453 | lib_ring_buffer_write_commit_counter(config, buf, chan, oldidx, |
80249235 | 1454 | offsets->old + padding_size, commit_count, handle); |
852c2936 MD |
1455 | } |
1456 | ||
1457 | /* | |
1458 | * lib_ring_buffer_switch_new_start: Populate new subbuffer. | |
1459 | * | |
1460 | * This code can be executed unordered : writers may already have written to the | |
1461 | * sub-buffer before this code gets executed, caution. The commit makes sure | |
1462 | * that this code is executed before the deliver of this sub-buffer. | |
1463 | */ | |
1464 | static | |
4cfec15c | 1465 | void lib_ring_buffer_switch_new_start(struct lttng_ust_lib_ring_buffer *buf, |
852c2936 MD |
1466 | struct channel *chan, |
1467 | struct switch_offsets *offsets, | |
2fed87ae | 1468 | uint64_t tsc, |
38fae1d3 | 1469 | struct lttng_ust_shm_handle *handle) |
852c2936 | 1470 | { |
4cfec15c | 1471 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
852c2936 MD |
1472 | unsigned long beginidx = subbuf_index(offsets->begin, chan); |
1473 | unsigned long commit_count; | |
1474 | ||
1d498196 | 1475 | config->cb.buffer_begin(buf, tsc, beginidx, handle); |
852c2936 MD |
1476 | |
1477 | /* | |
1478 | * Order all writes to buffer before the commit count update that will | |
1479 | * determine that the subbuffer is full. | |
1480 | */ | |
a6352fd4 | 1481 | cmm_smp_wmb(); |
852c2936 | 1482 | v_add(config, config->cb.subbuffer_header_size(), |
4746ae29 MD |
1483 | &shmp_index(handle, buf->commit_hot, beginidx)->cc); |
1484 | commit_count = v_read(config, &shmp_index(handle, buf->commit_hot, beginidx)->cc); | |
852c2936 MD |
1485 | /* Check if the written buffer has to be delivered */ |
1486 | lib_ring_buffer_check_deliver(config, buf, chan, offsets->begin, | |
1b7b0501 | 1487 | commit_count, beginidx, handle, tsc); |
852c2936 | 1488 | lib_ring_buffer_write_commit_counter(config, buf, chan, beginidx, |
80249235 MD |
1489 | offsets->begin + config->cb.subbuffer_header_size(), |
1490 | commit_count, handle); | |
852c2936 MD |
1491 | } |
1492 | ||
1ad21f70 MD |
1493 | /* |
1494 | * lib_ring_buffer_switch_new_end: finish switching current subbuffer | |
1495 | * | |
3962118d MD |
1496 | * Calls subbuffer_set_data_size() to set the data size of the current |
1497 | * sub-buffer. We do not need to perform check_deliver nor commit here, | |
1498 | * since this task will be done by the "commit" of the event for which | |
1499 | * we are currently doing the space reservation. | |
1ad21f70 MD |
1500 | */ |
1501 | static | |
1502 | void lib_ring_buffer_switch_new_end(struct lttng_ust_lib_ring_buffer *buf, | |
1503 | struct channel *chan, | |
1504 | struct switch_offsets *offsets, | |
1505 | uint64_t tsc, | |
1506 | struct lttng_ust_shm_handle *handle) | |
1507 | { | |
1508 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; | |
3962118d | 1509 | unsigned long endidx, data_size; |
1ad21f70 | 1510 | |
3962118d | 1511 | endidx = subbuf_index(offsets->end - 1, chan); |
1ad21f70 | 1512 | data_size = subbuf_offset(offsets->end - 1, chan) + 1; |
1ad21f70 MD |
1513 | subbuffer_set_data_size(config, &buf->backend, endidx, data_size, |
1514 | handle); | |
1ad21f70 MD |
1515 | } |
1516 | ||
852c2936 MD |
1517 | /* |
1518 | * Returns : | |
1519 | * 0 if ok | |
1520 | * !0 if execution must be aborted. | |
1521 | */ | |
1522 | static | |
1523 | int lib_ring_buffer_try_switch_slow(enum switch_mode mode, | |
4cfec15c | 1524 | struct lttng_ust_lib_ring_buffer *buf, |
852c2936 MD |
1525 | struct channel *chan, |
1526 | struct switch_offsets *offsets, | |
2dac206d MD |
1527 | uint64_t *tsc, |
1528 | struct lttng_ust_shm_handle *handle) | |
852c2936 | 1529 | { |
4cfec15c | 1530 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
2dac206d | 1531 | unsigned long off, reserve_commit_diff; |
852c2936 MD |
1532 | |
1533 | offsets->begin = v_read(config, &buf->offset); | |
1534 | offsets->old = offsets->begin; | |
1535 | offsets->switch_old_start = 0; | |
1536 | off = subbuf_offset(offsets->begin, chan); | |
1537 | ||
1538 | *tsc = config->cb.ring_buffer_clock_read(chan); | |
1539 | ||
1540 | /* | |
1541 | * Ensure we flush the header of an empty subbuffer when doing the | |
1542 | * finalize (SWITCH_FLUSH). This ensures that we end up knowing the | |
1543 | * total data gathering duration even if there were no records saved | |
1544 | * after the last buffer switch. | |
1545 | * In SWITCH_ACTIVE mode, switch the buffer when it contains events. | |
1546 | * SWITCH_ACTIVE only flushes the current subbuffer, dealing with end of | |
1547 | * subbuffer header as appropriate. | |
1548 | * The next record that reserves space will be responsible for | |
1549 | * populating the following subbuffer header. We choose not to populate | |
1550 | * the next subbuffer header here because we want to be able to use | |
a6352fd4 MD |
1551 | * SWITCH_ACTIVE for periodical buffer flush, which must |
1552 | * guarantee that all the buffer content (records and header | |
1553 | * timestamps) are visible to the reader. This is required for | |
1554 | * quiescence guarantees for the fusion merge. | |
852c2936 | 1555 | */ |
2dac206d MD |
1556 | if (mode != SWITCH_FLUSH && !off) |
1557 | return -1; /* we do not have to switch : buffer is empty */ | |
1558 | ||
1559 | if (caa_unlikely(off == 0)) { | |
1560 | unsigned long sb_index, commit_count; | |
1561 | ||
1562 | /* | |
1563 | * We are performing a SWITCH_FLUSH. At this stage, there are no | |
1564 | * concurrent writes into the buffer. | |
1565 | * | |
1566 | * The client does not save any header information. Don't | |
1567 | * switch empty subbuffer on finalize, because it is invalid to | |
1568 | * deliver a completely empty subbuffer. | |
1569 | */ | |
1570 | if (!config->cb.subbuffer_header_size()) | |
1571 | return -1; | |
1572 | ||
1573 | /* Test new buffer integrity */ | |
1574 | sb_index = subbuf_index(offsets->begin, chan); | |
1575 | commit_count = v_read(config, | |
1576 | &shmp_index(handle, buf->commit_cold, | |
1577 | sb_index)->cc_sb); | |
1578 | reserve_commit_diff = | |
1579 | (buf_trunc(offsets->begin, chan) | |
1580 | >> chan->backend.num_subbuf_order) | |
1581 | - (commit_count & chan->commit_count_mask); | |
1582 | if (caa_likely(reserve_commit_diff == 0)) { | |
1583 | /* Next subbuffer not being written to. */ | |
1584 | if (caa_unlikely(config->mode != RING_BUFFER_OVERWRITE && | |
1585 | subbuf_trunc(offsets->begin, chan) | |
1586 | - subbuf_trunc((unsigned long) | |
1587 | uatomic_read(&buf->consumed), chan) | |
1588 | >= chan->backend.buf_size)) { | |
1589 | /* | |
1590 | * We do not overwrite non consumed buffers | |
1591 | * and we are full : don't switch. | |
1592 | */ | |
852c2936 | 1593 | return -1; |
2dac206d MD |
1594 | } else { |
1595 | /* | |
1596 | * Next subbuffer not being written to, and we | |
1597 | * are either in overwrite mode or the buffer is | |
1598 | * not full. It's safe to write in this new | |
1599 | * subbuffer. | |
1600 | */ | |
1601 | } | |
1602 | } else { | |
852c2936 | 1603 | /* |
2dac206d MD |
1604 | * Next subbuffer reserve offset does not match the |
1605 | * commit offset. Don't perform switch in | |
1606 | * producer-consumer and overwrite mode. Caused by | |
1607 | * either a writer OOPS or too many nested writes over a | |
1608 | * reserve/commit pair. | |
852c2936 | 1609 | */ |
2dac206d | 1610 | return -1; |
852c2936 | 1611 | } |
2dac206d MD |
1612 | |
1613 | /* | |
1614 | * Need to write the subbuffer start header on finalize. | |
1615 | */ | |
1616 | offsets->switch_old_start = 1; | |
1617 | } | |
1618 | offsets->begin = subbuf_align(offsets->begin, chan); | |
852c2936 MD |
1619 | /* Note: old points to the next subbuf at offset 0 */ |
1620 | offsets->end = offsets->begin; | |
1621 | return 0; | |
1622 | } | |
1623 | ||
1624 | /* | |
1625 | * Force a sub-buffer switch. This operation is completely reentrant : can be | |
1626 | * called while tracing is active with absolutely no lock held. | |
1627 | * | |
1628 | * Note, however, that as a v_cmpxchg is used for some atomic | |
1629 | * operations, this function must be called from the CPU which owns the buffer | |
1630 | * for a ACTIVE flush. | |
1631 | */ | |
4cfec15c | 1632 | void lib_ring_buffer_switch_slow(struct lttng_ust_lib_ring_buffer *buf, enum switch_mode mode, |
38fae1d3 | 1633 | struct lttng_ust_shm_handle *handle) |
852c2936 | 1634 | { |
1d498196 | 1635 | struct channel *chan = shmp(handle, buf->backend.chan); |
4cfec15c | 1636 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
852c2936 MD |
1637 | struct switch_offsets offsets; |
1638 | unsigned long oldidx; | |
2fed87ae | 1639 | uint64_t tsc; |
852c2936 MD |
1640 | |
1641 | offsets.size = 0; | |
1642 | ||
1643 | /* | |
1644 | * Perform retryable operations. | |
1645 | */ | |
1646 | do { | |
1647 | if (lib_ring_buffer_try_switch_slow(mode, buf, chan, &offsets, | |
2dac206d | 1648 | &tsc, handle)) |
852c2936 MD |
1649 | return; /* Switch not needed */ |
1650 | } while (v_cmpxchg(config, &buf->offset, offsets.old, offsets.end) | |
1651 | != offsets.old); | |
1652 | ||
1653 | /* | |
1654 | * Atomically update last_tsc. This update races against concurrent | |
1655 | * atomic updates, but the race will always cause supplementary full TSC | |
1656 | * records, never the opposite (missing a full TSC record when it would | |
1657 | * be needed). | |
1658 | */ | |
1659 | save_last_tsc(config, buf, tsc); | |
1660 | ||
1661 | /* | |
1662 | * Push the reader if necessary | |
1663 | */ | |
1664 | lib_ring_buffer_reserve_push_reader(buf, chan, offsets.old); | |
1665 | ||
1666 | oldidx = subbuf_index(offsets.old, chan); | |
1d498196 | 1667 | lib_ring_buffer_clear_noref(config, &buf->backend, oldidx, handle); |
852c2936 MD |
1668 | |
1669 | /* | |
1670 | * May need to populate header start on SWITCH_FLUSH. | |
1671 | */ | |
1672 | if (offsets.switch_old_start) { | |
1d498196 | 1673 | lib_ring_buffer_switch_old_start(buf, chan, &offsets, tsc, handle); |
852c2936 MD |
1674 | offsets.old += config->cb.subbuffer_header_size(); |
1675 | } | |
1676 | ||
1677 | /* | |
1678 | * Switch old subbuffer. | |
1679 | */ | |
1d498196 | 1680 | lib_ring_buffer_switch_old_end(buf, chan, &offsets, tsc, handle); |
852c2936 | 1681 | } |
852c2936 MD |
1682 | |
1683 | /* | |
1684 | * Returns : | |
1685 | * 0 if ok | |
1686 | * -ENOSPC if event size is too large for packet. | |
1687 | * -ENOBUFS if there is currently not enough space in buffer for the event. | |
1688 | * -EIO if data cannot be written into the buffer for any other reason. | |
1689 | */ | |
1690 | static | |
4cfec15c | 1691 | int lib_ring_buffer_try_reserve_slow(struct lttng_ust_lib_ring_buffer *buf, |
852c2936 MD |
1692 | struct channel *chan, |
1693 | struct switch_offsets *offsets, | |
4cfec15c | 1694 | struct lttng_ust_lib_ring_buffer_ctx *ctx) |
852c2936 | 1695 | { |
4cfec15c | 1696 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
38fae1d3 | 1697 | struct lttng_ust_shm_handle *handle = ctx->handle; |
e185cf4b | 1698 | unsigned long reserve_commit_diff, offset_cmp; |
852c2936 | 1699 | |
e185cf4b MD |
1700 | retry: |
1701 | offsets->begin = offset_cmp = v_read(config, &buf->offset); | |
852c2936 MD |
1702 | offsets->old = offsets->begin; |
1703 | offsets->switch_new_start = 0; | |
1ad21f70 | 1704 | offsets->switch_new_end = 0; |
852c2936 MD |
1705 | offsets->switch_old_end = 0; |
1706 | offsets->pre_header_padding = 0; | |
1707 | ||
1708 | ctx->tsc = config->cb.ring_buffer_clock_read(chan); | |
1709 | if ((int64_t) ctx->tsc == -EIO) | |
1710 | return -EIO; | |
1711 | ||
1712 | if (last_tsc_overflow(config, buf, ctx->tsc)) | |
1713 | ctx->rflags |= RING_BUFFER_RFLAG_FULL_TSC; | |
1714 | ||
b5a3dfa5 | 1715 | if (caa_unlikely(subbuf_offset(offsets->begin, ctx->chan) == 0)) { |
852c2936 MD |
1716 | offsets->switch_new_start = 1; /* For offsets->begin */ |
1717 | } else { | |
1718 | offsets->size = config->cb.record_header_size(config, chan, | |
1719 | offsets->begin, | |
1720 | &offsets->pre_header_padding, | |
1721 | ctx); | |
1722 | offsets->size += | |
1723 | lib_ring_buffer_align(offsets->begin + offsets->size, | |
1724 | ctx->largest_align) | |
1725 | + ctx->data_size; | |
b5a3dfa5 | 1726 | if (caa_unlikely(subbuf_offset(offsets->begin, chan) + |
852c2936 MD |
1727 | offsets->size > chan->backend.subbuf_size)) { |
1728 | offsets->switch_old_end = 1; /* For offsets->old */ | |
1729 | offsets->switch_new_start = 1; /* For offsets->begin */ | |
1730 | } | |
1731 | } | |
b5a3dfa5 | 1732 | if (caa_unlikely(offsets->switch_new_start)) { |
e185cf4b | 1733 | unsigned long sb_index, commit_count; |
852c2936 MD |
1734 | |
1735 | /* | |
1736 | * We are typically not filling the previous buffer completely. | |
1737 | */ | |
b5a3dfa5 | 1738 | if (caa_likely(offsets->switch_old_end)) |
852c2936 MD |
1739 | offsets->begin = subbuf_align(offsets->begin, chan); |
1740 | offsets->begin = offsets->begin | |
1741 | + config->cb.subbuffer_header_size(); | |
1742 | /* Test new buffer integrity */ | |
1743 | sb_index = subbuf_index(offsets->begin, chan); | |
e185cf4b MD |
1744 | /* |
1745 | * Read buf->offset before buf->commit_cold[sb_index].cc_sb. | |
1746 | * lib_ring_buffer_check_deliver() has the matching | |
1747 | * memory barriers required around commit_cold cc_sb | |
1748 | * updates to ensure reserve and commit counter updates | |
1749 | * are not seen reordered when updated by another CPU. | |
1750 | */ | |
1751 | cmm_smp_rmb(); | |
1752 | commit_count = v_read(config, | |
1753 | &shmp_index(handle, buf->commit_cold, | |
1754 | sb_index)->cc_sb); | |
1755 | /* Read buf->commit_cold[sb_index].cc_sb before buf->offset. */ | |
1756 | cmm_smp_rmb(); | |
1757 | if (caa_unlikely(offset_cmp != v_read(config, &buf->offset))) { | |
1758 | /* | |
1759 | * The reserve counter have been concurrently updated | |
1760 | * while we read the commit counter. This means the | |
1761 | * commit counter we read might not match buf->offset | |
1762 | * due to concurrent update. We therefore need to retry. | |
1763 | */ | |
1764 | goto retry; | |
1765 | } | |
852c2936 MD |
1766 | reserve_commit_diff = |
1767 | (buf_trunc(offsets->begin, chan) | |
1768 | >> chan->backend.num_subbuf_order) | |
e185cf4b | 1769 | - (commit_count & chan->commit_count_mask); |
b5a3dfa5 | 1770 | if (caa_likely(reserve_commit_diff == 0)) { |
852c2936 | 1771 | /* Next subbuffer not being written to. */ |
b5a3dfa5 | 1772 | if (caa_unlikely(config->mode != RING_BUFFER_OVERWRITE && |
852c2936 MD |
1773 | subbuf_trunc(offsets->begin, chan) |
1774 | - subbuf_trunc((unsigned long) | |
a6352fd4 | 1775 | uatomic_read(&buf->consumed), chan) |
852c2936 | 1776 | >= chan->backend.buf_size)) { |
64493e4f MD |
1777 | unsigned long nr_lost; |
1778 | ||
852c2936 MD |
1779 | /* |
1780 | * We do not overwrite non consumed buffers | |
1781 | * and we are full : record is lost. | |
1782 | */ | |
64493e4f | 1783 | nr_lost = v_read(config, &buf->records_lost_full); |
852c2936 | 1784 | v_inc(config, &buf->records_lost_full); |
64493e4f MD |
1785 | if ((nr_lost & (DBG_PRINT_NR_LOST - 1)) == 0) { |
1786 | DBG("%lu or more records lost in (%s:%d) (buffer full)\n", | |
1787 | nr_lost + 1, chan->backend.name, | |
1788 | buf->backend.cpu); | |
1789 | } | |
852c2936 MD |
1790 | return -ENOBUFS; |
1791 | } else { | |
1792 | /* | |
1793 | * Next subbuffer not being written to, and we | |
1794 | * are either in overwrite mode or the buffer is | |
1795 | * not full. It's safe to write in this new | |
1796 | * subbuffer. | |
1797 | */ | |
1798 | } | |
1799 | } else { | |
64493e4f MD |
1800 | unsigned long nr_lost; |
1801 | ||
852c2936 MD |
1802 | /* |
1803 | * Next subbuffer reserve offset does not match the | |
e185cf4b MD |
1804 | * commit offset, and this did not involve update to the |
1805 | * reserve counter. Drop record in producer-consumer and | |
852c2936 MD |
1806 | * overwrite mode. Caused by either a writer OOPS or too |
1807 | * many nested writes over a reserve/commit pair. | |
1808 | */ | |
64493e4f | 1809 | nr_lost = v_read(config, &buf->records_lost_wrap); |
852c2936 | 1810 | v_inc(config, &buf->records_lost_wrap); |
64493e4f MD |
1811 | if ((nr_lost & (DBG_PRINT_NR_LOST - 1)) == 0) { |
1812 | DBG("%lu or more records lost in (%s:%d) (wrap-around)\n", | |
1813 | nr_lost + 1, chan->backend.name, | |
1814 | buf->backend.cpu); | |
1815 | } | |
852c2936 MD |
1816 | return -EIO; |
1817 | } | |
1818 | offsets->size = | |
1819 | config->cb.record_header_size(config, chan, | |
1820 | offsets->begin, | |
1821 | &offsets->pre_header_padding, | |
1822 | ctx); | |
1823 | offsets->size += | |
1824 | lib_ring_buffer_align(offsets->begin + offsets->size, | |
1825 | ctx->largest_align) | |
1826 | + ctx->data_size; | |
b5a3dfa5 | 1827 | if (caa_unlikely(subbuf_offset(offsets->begin, chan) |
852c2936 | 1828 | + offsets->size > chan->backend.subbuf_size)) { |
64493e4f MD |
1829 | unsigned long nr_lost; |
1830 | ||
852c2936 MD |
1831 | /* |
1832 | * Record too big for subbuffers, report error, don't | |
1833 | * complete the sub-buffer switch. | |
1834 | */ | |
64493e4f | 1835 | nr_lost = v_read(config, &buf->records_lost_big); |
852c2936 | 1836 | v_inc(config, &buf->records_lost_big); |
64493e4f MD |
1837 | if ((nr_lost & (DBG_PRINT_NR_LOST - 1)) == 0) { |
1838 | DBG("%lu or more records lost in (%s:%d) record size " | |
1839 | " of %zu bytes is too large for buffer\n", | |
1840 | nr_lost + 1, chan->backend.name, | |
1841 | buf->backend.cpu, offsets->size); | |
1842 | } | |
852c2936 MD |
1843 | return -ENOSPC; |
1844 | } else { | |
1845 | /* | |
1846 | * We just made a successful buffer switch and the | |
1847 | * record fits in the new subbuffer. Let's write. | |
1848 | */ | |
1849 | } | |
1850 | } else { | |
1851 | /* | |
1852 | * Record fits in the current buffer and we are not on a switch | |
1853 | * boundary. It's safe to write. | |
1854 | */ | |
1855 | } | |
1856 | offsets->end = offsets->begin + offsets->size; | |
1ad21f70 MD |
1857 | |
1858 | if (caa_unlikely(subbuf_offset(offsets->end, chan) == 0)) { | |
1859 | /* | |
1860 | * The offset_end will fall at the very beginning of the next | |
1861 | * subbuffer. | |
1862 | */ | |
1863 | offsets->switch_new_end = 1; /* For offsets->begin */ | |
1864 | } | |
852c2936 MD |
1865 | return 0; |
1866 | } | |
1867 | ||
1868 | /** | |
1869 | * lib_ring_buffer_reserve_slow - Atomic slot reservation in a buffer. | |
1870 | * @ctx: ring buffer context. | |
1871 | * | |
1872 | * Return : -NOBUFS if not enough space, -ENOSPC if event size too large, | |
1873 | * -EIO for other errors, else returns 0. | |
1874 | * It will take care of sub-buffer switching. | |
1875 | */ | |
4cfec15c | 1876 | int lib_ring_buffer_reserve_slow(struct lttng_ust_lib_ring_buffer_ctx *ctx) |
852c2936 MD |
1877 | { |
1878 | struct channel *chan = ctx->chan; | |
38fae1d3 | 1879 | struct lttng_ust_shm_handle *handle = ctx->handle; |
4cfec15c MD |
1880 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
1881 | struct lttng_ust_lib_ring_buffer *buf; | |
852c2936 MD |
1882 | struct switch_offsets offsets; |
1883 | int ret; | |
1884 | ||
1885 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) | |
1d498196 | 1886 | buf = shmp(handle, chan->backend.buf[ctx->cpu].shmp); |
852c2936 | 1887 | else |
1d498196 | 1888 | buf = shmp(handle, chan->backend.buf[0].shmp); |
852c2936 MD |
1889 | ctx->buf = buf; |
1890 | ||
1891 | offsets.size = 0; | |
1892 | ||
1893 | do { | |
1894 | ret = lib_ring_buffer_try_reserve_slow(buf, chan, &offsets, | |
1895 | ctx); | |
b5a3dfa5 | 1896 | if (caa_unlikely(ret)) |
852c2936 | 1897 | return ret; |
b5a3dfa5 | 1898 | } while (caa_unlikely(v_cmpxchg(config, &buf->offset, offsets.old, |
852c2936 MD |
1899 | offsets.end) |
1900 | != offsets.old)); | |
1901 | ||
1902 | /* | |
1903 | * Atomically update last_tsc. This update races against concurrent | |
1904 | * atomic updates, but the race will always cause supplementary full TSC | |
1905 | * records, never the opposite (missing a full TSC record when it would | |
1906 | * be needed). | |
1907 | */ | |
1908 | save_last_tsc(config, buf, ctx->tsc); | |
1909 | ||
1910 | /* | |
1911 | * Push the reader if necessary | |
1912 | */ | |
1913 | lib_ring_buffer_reserve_push_reader(buf, chan, offsets.end - 1); | |
1914 | ||
1915 | /* | |
1916 | * Clear noref flag for this subbuffer. | |
1917 | */ | |
1918 | lib_ring_buffer_clear_noref(config, &buf->backend, | |
1d498196 MD |
1919 | subbuf_index(offsets.end - 1, chan), |
1920 | handle); | |
852c2936 MD |
1921 | |
1922 | /* | |
1923 | * Switch old subbuffer if needed. | |
1924 | */ | |
b5a3dfa5 | 1925 | if (caa_unlikely(offsets.switch_old_end)) { |
852c2936 | 1926 | lib_ring_buffer_clear_noref(config, &buf->backend, |
1d498196 MD |
1927 | subbuf_index(offsets.old - 1, chan), |
1928 | handle); | |
1929 | lib_ring_buffer_switch_old_end(buf, chan, &offsets, ctx->tsc, handle); | |
852c2936 MD |
1930 | } |
1931 | ||
1932 | /* | |
1933 | * Populate new subbuffer. | |
1934 | */ | |
b5a3dfa5 | 1935 | if (caa_unlikely(offsets.switch_new_start)) |
1d498196 | 1936 | lib_ring_buffer_switch_new_start(buf, chan, &offsets, ctx->tsc, handle); |
852c2936 | 1937 | |
1ad21f70 MD |
1938 | if (caa_unlikely(offsets.switch_new_end)) |
1939 | lib_ring_buffer_switch_new_end(buf, chan, &offsets, ctx->tsc, handle); | |
1940 | ||
852c2936 MD |
1941 | ctx->slot_size = offsets.size; |
1942 | ctx->pre_offset = offsets.begin; | |
1943 | ctx->buf_offset = offsets.begin + offsets.pre_header_padding; | |
1944 | return 0; | |
1945 | } | |
f645cfa7 MD |
1946 | |
1947 | /* | |
1948 | * Force a read (imply TLS fixup for dlopen) of TLS variables. | |
1949 | */ | |
1950 | void lttng_fixup_ringbuffer_tls(void) | |
1951 | { | |
8c90a710 | 1952 | asm volatile ("" : : "m" (URCU_TLS(lib_ring_buffer_nesting))); |
f645cfa7 | 1953 | } |
03d2d293 MD |
1954 | |
1955 | void lib_ringbuffer_signal_init(void) | |
1956 | { | |
1957 | sigset_t mask; | |
1958 | int ret; | |
1959 | ||
1960 | /* | |
1961 | * Block signal for entire process, so only our thread processes | |
1962 | * it. | |
1963 | */ | |
1964 | rb_setmask(&mask); | |
1965 | ret = pthread_sigmask(SIG_BLOCK, &mask, NULL); | |
1966 | if (ret) { | |
1967 | errno = ret; | |
1968 | PERROR("pthread_sigmask"); | |
1969 | } | |
1970 | } |