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> |
35897f8b | 65 | #include <helper.h> |
14641deb | 66 | |
a6352fd4 | 67 | #include "smp.h" |
4318ae1b | 68 | #include <lttng/ringbuffer-config.h> |
2fed87ae | 69 | #include "vatomic.h" |
4931a13e MD |
70 | #include "backend.h" |
71 | #include "frontend.h" | |
a6352fd4 | 72 | #include "shm.h" |
f645cfa7 | 73 | #include "tlsfixup.h" |
bdcf8d82 | 74 | #include "../liblttng-ust/compat.h" /* For ENODATA */ |
852c2936 | 75 | |
431d5cf0 MD |
76 | #ifndef max |
77 | #define max(a, b) ((a) > (b) ? (a) : (b)) | |
78 | #endif | |
79 | ||
64493e4f MD |
80 | /* Print DBG() messages about events lost only every 1048576 hits */ |
81 | #define DBG_PRINT_NR_LOST (1UL << 20) | |
82 | ||
34a91bdb MD |
83 | #define LTTNG_UST_RB_SIG_FLUSH SIGRTMIN |
84 | #define LTTNG_UST_RB_SIG_READ SIGRTMIN + 1 | |
85 | #define LTTNG_UST_RB_SIG_TEARDOWN SIGRTMIN + 2 | |
03d2d293 | 86 | #define CLOCKID CLOCK_MONOTONIC |
57ebc611 MD |
87 | #define LTTNG_UST_RING_BUFFER_GET_RETRY 10 |
88 | #define LTTNG_UST_RING_BUFFER_RETRY_DELAY_MS 10 | |
03d2d293 | 89 | |
2432c3c9 MD |
90 | /* |
91 | * Use POSIX SHM: shm_open(3) and shm_unlink(3). | |
92 | * close(2) to close the fd returned by shm_open. | |
93 | * shm_unlink releases the shared memory object name. | |
94 | * ftruncate(2) sets the size of the memory object. | |
95 | * mmap/munmap maps the shared memory obj to a virtual address in the | |
96 | * calling proceess (should be done both in libust and consumer). | |
97 | * See shm_overview(7) for details. | |
98 | * Pass file descriptor returned by shm_open(3) to ltt-sessiond through | |
99 | * a UNIX socket. | |
100 | * | |
101 | * Since we don't need to access the object using its name, we can | |
102 | * immediately shm_unlink(3) it, and only keep the handle with its file | |
103 | * descriptor. | |
104 | */ | |
105 | ||
852c2936 MD |
106 | /* |
107 | * Internal structure representing offsets to use at a sub-buffer switch. | |
108 | */ | |
109 | struct switch_offsets { | |
110 | unsigned long begin, end, old; | |
111 | size_t pre_header_padding, size; | |
1ad21f70 MD |
112 | unsigned int switch_new_start:1, switch_new_end:1, switch_old_start:1, |
113 | switch_old_end:1; | |
852c2936 MD |
114 | }; |
115 | ||
8c90a710 | 116 | DEFINE_URCU_TLS(unsigned int, lib_ring_buffer_nesting); |
852c2936 | 117 | |
cb7378b3 MD |
118 | /* |
119 | * wakeup_fd_mutex protects wakeup fd use by timer from concurrent | |
120 | * close. | |
121 | */ | |
122 | static pthread_mutex_t wakeup_fd_mutex = PTHREAD_MUTEX_INITIALIZER; | |
123 | ||
852c2936 MD |
124 | static |
125 | void lib_ring_buffer_print_errors(struct channel *chan, | |
009769ca MD |
126 | struct lttng_ust_lib_ring_buffer *buf, int cpu, |
127 | struct lttng_ust_shm_handle *handle); | |
852c2936 | 128 | |
03d2d293 MD |
129 | /* |
130 | * Handle timer teardown race wrt memory free of private data by | |
131 | * ring buffer signals are handled by a single thread, which permits | |
132 | * a synchronization point between handling of each signal. | |
64bf51a6 | 133 | * Protected by the lock within the structure. |
03d2d293 MD |
134 | */ |
135 | struct timer_signal_data { | |
136 | pthread_t tid; /* thread id managing signals */ | |
137 | int setup_done; | |
138 | int qs_done; | |
64bf51a6 | 139 | pthread_mutex_t lock; |
03d2d293 MD |
140 | }; |
141 | ||
64bf51a6 MD |
142 | static struct timer_signal_data timer_signal = { |
143 | .tid = 0, | |
144 | .setup_done = 0, | |
145 | .qs_done = 0, | |
146 | .lock = PTHREAD_MUTEX_INITIALIZER, | |
147 | }; | |
03d2d293 | 148 | |
852c2936 MD |
149 | /** |
150 | * lib_ring_buffer_reset - Reset ring buffer to initial values. | |
151 | * @buf: Ring buffer. | |
152 | * | |
153 | * Effectively empty the ring buffer. Should be called when the buffer is not | |
154 | * used for writing. The ring buffer can be opened for reading, but the reader | |
155 | * should not be using the iterator concurrently with reset. The previous | |
156 | * current iterator record is reset. | |
157 | */ | |
4cfec15c | 158 | void lib_ring_buffer_reset(struct lttng_ust_lib_ring_buffer *buf, |
38fae1d3 | 159 | struct lttng_ust_shm_handle *handle) |
852c2936 | 160 | { |
1d498196 | 161 | struct channel *chan = shmp(handle, buf->backend.chan); |
4cfec15c | 162 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
852c2936 MD |
163 | unsigned int i; |
164 | ||
165 | /* | |
166 | * Reset iterator first. It will put the subbuffer if it currently holds | |
167 | * it. | |
168 | */ | |
852c2936 MD |
169 | v_set(config, &buf->offset, 0); |
170 | for (i = 0; i < chan->backend.num_subbuf; i++) { | |
4746ae29 MD |
171 | v_set(config, &shmp_index(handle, buf->commit_hot, i)->cc, 0); |
172 | v_set(config, &shmp_index(handle, buf->commit_hot, i)->seq, 0); | |
173 | v_set(config, &shmp_index(handle, buf->commit_cold, i)->cc_sb, 0); | |
852c2936 | 174 | } |
a6352fd4 MD |
175 | uatomic_set(&buf->consumed, 0); |
176 | uatomic_set(&buf->record_disabled, 0); | |
852c2936 | 177 | v_set(config, &buf->last_tsc, 0); |
1d498196 | 178 | lib_ring_buffer_backend_reset(&buf->backend, handle); |
852c2936 MD |
179 | /* Don't reset number of active readers */ |
180 | v_set(config, &buf->records_lost_full, 0); | |
181 | v_set(config, &buf->records_lost_wrap, 0); | |
182 | v_set(config, &buf->records_lost_big, 0); | |
183 | v_set(config, &buf->records_count, 0); | |
184 | v_set(config, &buf->records_overrun, 0); | |
185 | buf->finalized = 0; | |
186 | } | |
852c2936 MD |
187 | |
188 | /** | |
189 | * channel_reset - Reset channel to initial values. | |
190 | * @chan: Channel. | |
191 | * | |
192 | * Effectively empty the channel. Should be called when the channel is not used | |
193 | * for writing. The channel can be opened for reading, but the reader should not | |
194 | * be using the iterator concurrently with reset. The previous current iterator | |
195 | * record is reset. | |
196 | */ | |
197 | void channel_reset(struct channel *chan) | |
198 | { | |
199 | /* | |
200 | * Reset iterators first. Will put the subbuffer if held for reading. | |
201 | */ | |
a6352fd4 | 202 | uatomic_set(&chan->record_disabled, 0); |
852c2936 MD |
203 | /* Don't reset commit_count_mask, still valid */ |
204 | channel_backend_reset(&chan->backend); | |
205 | /* Don't reset switch/read timer interval */ | |
206 | /* Don't reset notifiers and notifier enable bits */ | |
207 | /* Don't reset reader reference count */ | |
208 | } | |
852c2936 MD |
209 | |
210 | /* | |
211 | * Must be called under cpu hotplug protection. | |
212 | */ | |
4cfec15c | 213 | int lib_ring_buffer_create(struct lttng_ust_lib_ring_buffer *buf, |
a6352fd4 | 214 | struct channel_backend *chanb, int cpu, |
38fae1d3 | 215 | struct lttng_ust_shm_handle *handle, |
1d498196 | 216 | struct shm_object *shmobj) |
852c2936 | 217 | { |
4cfec15c | 218 | const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config; |
14641deb | 219 | struct channel *chan = caa_container_of(chanb, struct channel, backend); |
a3f61e7f | 220 | void *priv = channel_get_private(chan); |
852c2936 | 221 | size_t subbuf_header_size; |
2fed87ae | 222 | uint64_t tsc; |
852c2936 MD |
223 | int ret; |
224 | ||
225 | /* Test for cpu hotplug */ | |
226 | if (buf->backend.allocated) | |
227 | return 0; | |
228 | ||
a6352fd4 | 229 | ret = lib_ring_buffer_backend_create(&buf->backend, &chan->backend, |
1d498196 | 230 | cpu, handle, shmobj); |
852c2936 MD |
231 | if (ret) |
232 | return ret; | |
233 | ||
1d498196 MD |
234 | align_shm(shmobj, __alignof__(struct commit_counters_hot)); |
235 | set_shmp(buf->commit_hot, | |
236 | zalloc_shm(shmobj, | |
237 | sizeof(struct commit_counters_hot) * chan->backend.num_subbuf)); | |
238 | if (!shmp(handle, buf->commit_hot)) { | |
852c2936 MD |
239 | ret = -ENOMEM; |
240 | goto free_chanbuf; | |
241 | } | |
242 | ||
1d498196 MD |
243 | align_shm(shmobj, __alignof__(struct commit_counters_cold)); |
244 | set_shmp(buf->commit_cold, | |
245 | zalloc_shm(shmobj, | |
246 | sizeof(struct commit_counters_cold) * chan->backend.num_subbuf)); | |
247 | if (!shmp(handle, buf->commit_cold)) { | |
852c2936 MD |
248 | ret = -ENOMEM; |
249 | goto free_commit; | |
250 | } | |
251 | ||
852c2936 MD |
252 | /* |
253 | * Write the subbuffer header for first subbuffer so we know the total | |
254 | * duration of data gathering. | |
255 | */ | |
256 | subbuf_header_size = config->cb.subbuffer_header_size(); | |
257 | v_set(config, &buf->offset, subbuf_header_size); | |
4746ae29 | 258 | subbuffer_id_clear_noref(config, &shmp_index(handle, buf->backend.buf_wsb, 0)->id); |
1d498196 MD |
259 | tsc = config->cb.ring_buffer_clock_read(shmp(handle, buf->backend.chan)); |
260 | config->cb.buffer_begin(buf, tsc, 0, handle); | |
4746ae29 | 261 | v_add(config, subbuf_header_size, &shmp_index(handle, buf->commit_hot, 0)->cc); |
852c2936 MD |
262 | |
263 | if (config->cb.buffer_create) { | |
1d498196 | 264 | ret = config->cb.buffer_create(buf, priv, cpu, chanb->name, handle); |
852c2936 MD |
265 | if (ret) |
266 | goto free_init; | |
267 | } | |
852c2936 | 268 | buf->backend.allocated = 1; |
852c2936 MD |
269 | return 0; |
270 | ||
271 | /* Error handling */ | |
272 | free_init: | |
a6352fd4 | 273 | /* commit_cold will be freed by shm teardown */ |
852c2936 | 274 | free_commit: |
a6352fd4 | 275 | /* commit_hot will be freed by shm teardown */ |
852c2936 | 276 | free_chanbuf: |
852c2936 MD |
277 | return ret; |
278 | } | |
279 | ||
03d2d293 MD |
280 | static |
281 | void lib_ring_buffer_channel_switch_timer(int sig, siginfo_t *si, void *uc) | |
852c2936 | 282 | { |
03d2d293 MD |
283 | const struct lttng_ust_lib_ring_buffer_config *config; |
284 | struct lttng_ust_shm_handle *handle; | |
285 | struct channel *chan; | |
286 | int cpu; | |
287 | ||
288 | assert(CMM_LOAD_SHARED(timer_signal.tid) == pthread_self()); | |
289 | ||
290 | chan = si->si_value.sival_ptr; | |
291 | handle = chan->handle; | |
292 | config = &chan->backend.config; | |
852c2936 | 293 | |
34a91bdb | 294 | DBG("Switch timer for channel %p\n", chan); |
03d2d293 | 295 | |
4dcd7e80 MD |
296 | /* |
297 | * Only flush buffers periodically if readers are active. | |
298 | */ | |
cb7378b3 | 299 | pthread_mutex_lock(&wakeup_fd_mutex); |
03d2d293 MD |
300 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { |
301 | for_each_possible_cpu(cpu) { | |
302 | struct lttng_ust_lib_ring_buffer *buf = | |
303 | shmp(handle, chan->backend.buf[cpu].shmp); | |
4dcd7e80 MD |
304 | if (uatomic_read(&buf->active_readers)) |
305 | lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE, | |
306 | chan->handle); | |
03d2d293 MD |
307 | } |
308 | } else { | |
309 | struct lttng_ust_lib_ring_buffer *buf = | |
310 | shmp(handle, chan->backend.buf[0].shmp); | |
311 | ||
34a91bdb MD |
312 | if (uatomic_read(&buf->active_readers)) |
313 | lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE, | |
314 | chan->handle); | |
315 | } | |
316 | pthread_mutex_unlock(&wakeup_fd_mutex); | |
317 | return; | |
318 | } | |
319 | ||
320 | static | |
321 | void lib_ring_buffer_channel_do_read(struct channel *chan) | |
322 | { | |
323 | const struct lttng_ust_lib_ring_buffer_config *config; | |
324 | struct lttng_ust_shm_handle *handle; | |
325 | int cpu; | |
326 | ||
327 | handle = chan->handle; | |
328 | config = &chan->backend.config; | |
329 | ||
330 | /* | |
331 | * Only flush buffers periodically if readers are active. | |
332 | */ | |
333 | pthread_mutex_lock(&wakeup_fd_mutex); | |
334 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { | |
335 | for_each_possible_cpu(cpu) { | |
336 | struct lttng_ust_lib_ring_buffer *buf = | |
337 | shmp(handle, chan->backend.buf[cpu].shmp); | |
338 | ||
339 | if (uatomic_read(&buf->active_readers) | |
340 | && lib_ring_buffer_poll_deliver(config, buf, | |
341 | chan, handle)) { | |
342 | lib_ring_buffer_wakeup(buf, handle); | |
343 | } | |
344 | } | |
345 | } else { | |
346 | struct lttng_ust_lib_ring_buffer *buf = | |
347 | shmp(handle, chan->backend.buf[0].shmp); | |
348 | ||
349 | if (uatomic_read(&buf->active_readers) | |
350 | && lib_ring_buffer_poll_deliver(config, buf, | |
351 | chan, handle)) { | |
352 | lib_ring_buffer_wakeup(buf, handle); | |
353 | } | |
03d2d293 | 354 | } |
cb7378b3 | 355 | pthread_mutex_unlock(&wakeup_fd_mutex); |
34a91bdb MD |
356 | } |
357 | ||
358 | static | |
359 | void lib_ring_buffer_channel_read_timer(int sig, siginfo_t *si, void *uc) | |
360 | { | |
361 | struct channel *chan; | |
362 | ||
363 | assert(CMM_LOAD_SHARED(timer_signal.tid) == pthread_self()); | |
364 | chan = si->si_value.sival_ptr; | |
365 | DBG("Read timer for channel %p\n", chan); | |
366 | lib_ring_buffer_channel_do_read(chan); | |
03d2d293 MD |
367 | return; |
368 | } | |
369 | ||
370 | static | |
371 | void rb_setmask(sigset_t *mask) | |
372 | { | |
373 | int ret; | |
374 | ||
375 | ret = sigemptyset(mask); | |
376 | if (ret) { | |
377 | PERROR("sigemptyset"); | |
378 | } | |
34a91bdb MD |
379 | ret = sigaddset(mask, LTTNG_UST_RB_SIG_FLUSH); |
380 | if (ret) { | |
381 | PERROR("sigaddset"); | |
382 | } | |
383 | ret = sigaddset(mask, LTTNG_UST_RB_SIG_READ); | |
03d2d293 MD |
384 | if (ret) { |
385 | PERROR("sigaddset"); | |
386 | } | |
387 | ret = sigaddset(mask, LTTNG_UST_RB_SIG_TEARDOWN); | |
388 | if (ret) { | |
389 | PERROR("sigaddset"); | |
390 | } | |
391 | } | |
392 | ||
393 | static | |
394 | void *sig_thread(void *arg) | |
395 | { | |
396 | sigset_t mask; | |
397 | siginfo_t info; | |
398 | int signr; | |
399 | ||
400 | /* Only self thread will receive signal mask. */ | |
401 | rb_setmask(&mask); | |
402 | CMM_STORE_SHARED(timer_signal.tid, pthread_self()); | |
403 | ||
404 | for (;;) { | |
405 | signr = sigwaitinfo(&mask, &info); | |
406 | if (signr == -1) { | |
34a91bdb MD |
407 | if (errno != EINTR) |
408 | PERROR("sigwaitinfo"); | |
03d2d293 MD |
409 | continue; |
410 | } | |
34a91bdb | 411 | if (signr == LTTNG_UST_RB_SIG_FLUSH) { |
03d2d293 MD |
412 | lib_ring_buffer_channel_switch_timer(info.si_signo, |
413 | &info, NULL); | |
34a91bdb MD |
414 | } else if (signr == LTTNG_UST_RB_SIG_READ) { |
415 | lib_ring_buffer_channel_read_timer(info.si_signo, | |
416 | &info, NULL); | |
03d2d293 MD |
417 | } else if (signr == LTTNG_UST_RB_SIG_TEARDOWN) { |
418 | cmm_smp_mb(); | |
419 | CMM_STORE_SHARED(timer_signal.qs_done, 1); | |
420 | cmm_smp_mb(); | |
421 | } else { | |
422 | ERR("Unexptected signal %d\n", info.si_signo); | |
423 | } | |
424 | } | |
425 | return NULL; | |
426 | } | |
427 | ||
428 | /* | |
03d2d293 MD |
429 | * Ensure only a single thread listens on the timer signal. |
430 | */ | |
431 | static | |
432 | void lib_ring_buffer_setup_timer_thread(void) | |
433 | { | |
434 | pthread_t thread; | |
435 | int ret; | |
436 | ||
64bf51a6 | 437 | pthread_mutex_lock(&timer_signal.lock); |
03d2d293 | 438 | if (timer_signal.setup_done) |
64bf51a6 | 439 | goto end; |
03d2d293 MD |
440 | |
441 | ret = pthread_create(&thread, NULL, &sig_thread, NULL); | |
442 | if (ret) { | |
443 | errno = ret; | |
444 | PERROR("pthread_create"); | |
445 | } | |
446 | ret = pthread_detach(thread); | |
447 | if (ret) { | |
448 | errno = ret; | |
449 | PERROR("pthread_detach"); | |
450 | } | |
451 | timer_signal.setup_done = 1; | |
64bf51a6 MD |
452 | end: |
453 | pthread_mutex_unlock(&timer_signal.lock); | |
852c2936 MD |
454 | } |
455 | ||
03d2d293 | 456 | /* |
64bf51a6 | 457 | * Wait for signal-handling thread quiescent state. |
03d2d293 | 458 | */ |
64bf51a6 MD |
459 | static |
460 | void lib_ring_buffer_wait_signal_thread_qs(unsigned int signr) | |
461 | { | |
462 | sigset_t pending_set; | |
463 | int ret; | |
464 | ||
465 | /* | |
466 | * We need to be the only thread interacting with the thread | |
467 | * that manages signals for teardown synchronization. | |
468 | */ | |
469 | pthread_mutex_lock(&timer_signal.lock); | |
470 | ||
471 | /* | |
472 | * Ensure we don't have any signal queued for this channel. | |
473 | */ | |
474 | for (;;) { | |
475 | ret = sigemptyset(&pending_set); | |
476 | if (ret == -1) { | |
477 | PERROR("sigemptyset"); | |
478 | } | |
479 | ret = sigpending(&pending_set); | |
480 | if (ret == -1) { | |
481 | PERROR("sigpending"); | |
482 | } | |
483 | if (!sigismember(&pending_set, signr)) | |
484 | break; | |
485 | caa_cpu_relax(); | |
486 | } | |
487 | ||
488 | /* | |
489 | * From this point, no new signal handler will be fired that | |
490 | * would try to access "chan". However, we still need to wait | |
491 | * for any currently executing handler to complete. | |
492 | */ | |
493 | cmm_smp_mb(); | |
494 | CMM_STORE_SHARED(timer_signal.qs_done, 0); | |
495 | cmm_smp_mb(); | |
496 | ||
497 | /* | |
498 | * Kill with LTTNG_UST_RB_SIG_TEARDOWN, so signal management | |
499 | * thread wakes up. | |
500 | */ | |
501 | kill(getpid(), LTTNG_UST_RB_SIG_TEARDOWN); | |
502 | ||
503 | while (!CMM_LOAD_SHARED(timer_signal.qs_done)) | |
504 | caa_cpu_relax(); | |
505 | cmm_smp_mb(); | |
506 | ||
507 | pthread_mutex_unlock(&timer_signal.lock); | |
508 | } | |
509 | ||
03d2d293 MD |
510 | static |
511 | void lib_ring_buffer_channel_switch_timer_start(struct channel *chan) | |
852c2936 | 512 | { |
03d2d293 MD |
513 | struct sigevent sev; |
514 | struct itimerspec its; | |
515 | int ret; | |
852c2936 | 516 | |
03d2d293 | 517 | if (!chan->switch_timer_interval || chan->switch_timer_enabled) |
852c2936 MD |
518 | return; |
519 | ||
03d2d293 MD |
520 | chan->switch_timer_enabled = 1; |
521 | ||
522 | lib_ring_buffer_setup_timer_thread(); | |
523 | ||
524 | sev.sigev_notify = SIGEV_SIGNAL; | |
34a91bdb | 525 | sev.sigev_signo = LTTNG_UST_RB_SIG_FLUSH; |
03d2d293 MD |
526 | sev.sigev_value.sival_ptr = chan; |
527 | ret = timer_create(CLOCKID, &sev, &chan->switch_timer); | |
528 | if (ret == -1) { | |
529 | PERROR("timer_create"); | |
530 | } | |
531 | ||
532 | its.it_value.tv_sec = chan->switch_timer_interval / 1000000; | |
533 | its.it_value.tv_nsec = chan->switch_timer_interval % 1000000; | |
534 | its.it_interval.tv_sec = its.it_value.tv_sec; | |
535 | its.it_interval.tv_nsec = its.it_value.tv_nsec; | |
536 | ||
537 | ret = timer_settime(chan->switch_timer, 0, &its, NULL); | |
538 | if (ret == -1) { | |
539 | PERROR("timer_settime"); | |
540 | } | |
541 | } | |
542 | ||
03d2d293 MD |
543 | static |
544 | void lib_ring_buffer_channel_switch_timer_stop(struct channel *chan) | |
545 | { | |
34a91bdb | 546 | int ret; |
03d2d293 MD |
547 | |
548 | if (!chan->switch_timer_interval || !chan->switch_timer_enabled) | |
549 | return; | |
550 | ||
551 | ret = timer_delete(chan->switch_timer); | |
552 | if (ret == -1) { | |
553 | PERROR("timer_delete"); | |
554 | } | |
555 | ||
64bf51a6 | 556 | lib_ring_buffer_wait_signal_thread_qs(LTTNG_UST_RB_SIG_FLUSH); |
03d2d293 MD |
557 | |
558 | chan->switch_timer = 0; | |
559 | chan->switch_timer_enabled = 0; | |
852c2936 MD |
560 | } |
561 | ||
34a91bdb MD |
562 | static |
563 | void lib_ring_buffer_channel_read_timer_start(struct channel *chan) | |
852c2936 | 564 | { |
4cfec15c | 565 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
34a91bdb MD |
566 | struct sigevent sev; |
567 | struct itimerspec its; | |
568 | int ret; | |
852c2936 | 569 | |
34a91bdb MD |
570 | if (config->wakeup != RING_BUFFER_WAKEUP_BY_TIMER |
571 | || !chan->read_timer_interval || chan->read_timer_enabled) | |
572 | return; | |
852c2936 | 573 | |
34a91bdb | 574 | chan->read_timer_enabled = 1; |
852c2936 | 575 | |
34a91bdb | 576 | lib_ring_buffer_setup_timer_thread(); |
852c2936 | 577 | |
34a91bdb MD |
578 | sev.sigev_notify = SIGEV_SIGNAL; |
579 | sev.sigev_signo = LTTNG_UST_RB_SIG_READ; | |
580 | sev.sigev_value.sival_ptr = chan; | |
581 | ret = timer_create(CLOCKID, &sev, &chan->read_timer); | |
582 | if (ret == -1) { | |
583 | PERROR("timer_create"); | |
584 | } | |
852c2936 | 585 | |
34a91bdb MD |
586 | its.it_value.tv_sec = chan->read_timer_interval / 1000000; |
587 | its.it_value.tv_nsec = chan->read_timer_interval % 1000000; | |
588 | its.it_interval.tv_sec = its.it_value.tv_sec; | |
589 | its.it_interval.tv_nsec = its.it_value.tv_nsec; | |
852c2936 | 590 | |
34a91bdb MD |
591 | ret = timer_settime(chan->read_timer, 0, &its, NULL); |
592 | if (ret == -1) { | |
593 | PERROR("timer_settime"); | |
594 | } | |
852c2936 MD |
595 | } |
596 | ||
34a91bdb MD |
597 | static |
598 | void lib_ring_buffer_channel_read_timer_stop(struct channel *chan) | |
852c2936 | 599 | { |
4cfec15c | 600 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
34a91bdb | 601 | int ret; |
852c2936 MD |
602 | |
603 | if (config->wakeup != RING_BUFFER_WAKEUP_BY_TIMER | |
34a91bdb | 604 | || !chan->read_timer_interval || !chan->read_timer_enabled) |
852c2936 MD |
605 | return; |
606 | ||
34a91bdb MD |
607 | ret = timer_delete(chan->read_timer); |
608 | if (ret == -1) { | |
609 | PERROR("timer_delete"); | |
610 | } | |
611 | ||
852c2936 MD |
612 | /* |
613 | * do one more check to catch data that has been written in the last | |
614 | * timer period. | |
615 | */ | |
34a91bdb MD |
616 | lib_ring_buffer_channel_do_read(chan); |
617 | ||
64bf51a6 | 618 | lib_ring_buffer_wait_signal_thread_qs(LTTNG_UST_RB_SIG_READ); |
34a91bdb MD |
619 | |
620 | chan->read_timer = 0; | |
621 | chan->read_timer_enabled = 0; | |
852c2936 MD |
622 | } |
623 | ||
1d498196 | 624 | static void channel_unregister_notifiers(struct channel *chan, |
38fae1d3 | 625 | struct lttng_ust_shm_handle *handle) |
852c2936 | 626 | { |
03d2d293 | 627 | lib_ring_buffer_channel_switch_timer_stop(chan); |
34a91bdb | 628 | lib_ring_buffer_channel_read_timer_stop(chan); |
852c2936 MD |
629 | } |
630 | ||
009769ca MD |
631 | static void channel_print_errors(struct channel *chan, |
632 | struct lttng_ust_shm_handle *handle) | |
633 | { | |
634 | const struct lttng_ust_lib_ring_buffer_config *config = | |
635 | &chan->backend.config; | |
636 | int cpu; | |
637 | ||
638 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { | |
639 | for_each_possible_cpu(cpu) { | |
640 | struct lttng_ust_lib_ring_buffer *buf = | |
641 | shmp(handle, chan->backend.buf[cpu].shmp); | |
642 | lib_ring_buffer_print_errors(chan, buf, cpu, handle); | |
643 | } | |
644 | } else { | |
645 | struct lttng_ust_lib_ring_buffer *buf = | |
646 | shmp(handle, chan->backend.buf[0].shmp); | |
647 | ||
648 | lib_ring_buffer_print_errors(chan, buf, -1, handle); | |
649 | } | |
650 | } | |
651 | ||
652 | static void channel_free(struct channel *chan, | |
653 | struct lttng_ust_shm_handle *handle) | |
852c2936 | 654 | { |
74d81a6c | 655 | channel_backend_free(&chan->backend, handle); |
431d5cf0 | 656 | /* chan is freed by shm teardown */ |
1d498196 MD |
657 | shm_object_table_destroy(handle->table); |
658 | free(handle); | |
852c2936 MD |
659 | } |
660 | ||
661 | /** | |
662 | * channel_create - Create channel. | |
663 | * @config: ring buffer instance configuration | |
664 | * @name: name of the channel | |
a3f61e7f MD |
665 | * @priv_data: ring buffer client private data area pointer (output) |
666 | * @priv_data_size: length, in bytes, of the private data area. | |
d028eddb | 667 | * @priv_data_init: initialization data for private data. |
852c2936 MD |
668 | * @buf_addr: pointer the the beginning of the preallocated buffer contiguous |
669 | * address mapping. It is used only by RING_BUFFER_STATIC | |
670 | * configuration. It can be set to NULL for other backends. | |
671 | * @subbuf_size: subbuffer size | |
672 | * @num_subbuf: number of subbuffers | |
673 | * @switch_timer_interval: Time interval (in us) to fill sub-buffers with | |
674 | * padding to let readers get those sub-buffers. | |
675 | * Used for live streaming. | |
676 | * @read_timer_interval: Time interval (in us) to wake up pending readers. | |
677 | * | |
678 | * Holds cpu hotplug. | |
679 | * Returns NULL on failure. | |
680 | */ | |
4cfec15c | 681 | struct lttng_ust_shm_handle *channel_create(const struct lttng_ust_lib_ring_buffer_config *config, |
a3f61e7f MD |
682 | const char *name, |
683 | void **priv_data, | |
684 | size_t priv_data_align, | |
685 | size_t priv_data_size, | |
d028eddb | 686 | void *priv_data_init, |
a3f61e7f | 687 | void *buf_addr, size_t subbuf_size, |
852c2936 | 688 | size_t num_subbuf, unsigned int switch_timer_interval, |
74d81a6c | 689 | unsigned int read_timer_interval) |
852c2936 | 690 | { |
24622edc | 691 | int ret; |
a3f61e7f | 692 | size_t shmsize, chansize; |
852c2936 | 693 | struct channel *chan; |
38fae1d3 | 694 | struct lttng_ust_shm_handle *handle; |
1d498196 | 695 | struct shm_object *shmobj; |
74d81a6c MD |
696 | unsigned int nr_streams; |
697 | ||
698 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) | |
699 | nr_streams = num_possible_cpus(); | |
700 | else | |
701 | nr_streams = 1; | |
852c2936 MD |
702 | |
703 | if (lib_ring_buffer_check_config(config, switch_timer_interval, | |
704 | read_timer_interval)) | |
705 | return NULL; | |
706 | ||
38fae1d3 | 707 | handle = zmalloc(sizeof(struct lttng_ust_shm_handle)); |
431d5cf0 MD |
708 | if (!handle) |
709 | return NULL; | |
710 | ||
1d498196 MD |
711 | /* Allocate table for channel + per-cpu buffers */ |
712 | handle->table = shm_object_table_create(1 + num_possible_cpus()); | |
713 | if (!handle->table) | |
714 | goto error_table_alloc; | |
852c2936 | 715 | |
1d498196 MD |
716 | /* Calculate the shm allocation layout */ |
717 | shmsize = sizeof(struct channel); | |
c1fca457 | 718 | shmsize += offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_shmp)); |
74d81a6c | 719 | shmsize += sizeof(struct lttng_ust_lib_ring_buffer_shmp) * nr_streams; |
a3f61e7f | 720 | chansize = shmsize; |
74d81a6c MD |
721 | if (priv_data_align) |
722 | shmsize += offset_align(shmsize, priv_data_align); | |
a3f61e7f | 723 | shmsize += priv_data_size; |
a6352fd4 | 724 | |
74d81a6c MD |
725 | /* Allocate normal memory for channel (not shared) */ |
726 | shmobj = shm_object_table_alloc(handle->table, shmsize, SHM_OBJECT_MEM); | |
b5a14697 MD |
727 | if (!shmobj) |
728 | goto error_append; | |
57773204 | 729 | /* struct channel is at object 0, offset 0 (hardcoded) */ |
a3f61e7f | 730 | set_shmp(handle->chan, zalloc_shm(shmobj, chansize)); |
57773204 MD |
731 | assert(handle->chan._ref.index == 0); |
732 | assert(handle->chan._ref.offset == 0); | |
1d498196 | 733 | chan = shmp(handle, handle->chan); |
a6352fd4 | 734 | if (!chan) |
1d498196 | 735 | goto error_append; |
74d81a6c | 736 | chan->nr_streams = nr_streams; |
a6352fd4 | 737 | |
a3f61e7f MD |
738 | /* space for private data */ |
739 | if (priv_data_size) { | |
740 | DECLARE_SHMP(void, priv_data_alloc); | |
741 | ||
742 | align_shm(shmobj, priv_data_align); | |
743 | chan->priv_data_offset = shmobj->allocated_len; | |
744 | set_shmp(priv_data_alloc, zalloc_shm(shmobj, priv_data_size)); | |
745 | if (!shmp(handle, priv_data_alloc)) | |
746 | goto error_append; | |
747 | *priv_data = channel_get_private(chan); | |
d028eddb | 748 | memcpy(*priv_data, priv_data_init, priv_data_size); |
a3f61e7f MD |
749 | } else { |
750 | chan->priv_data_offset = -1; | |
74d81a6c MD |
751 | if (priv_data) |
752 | *priv_data = NULL; | |
a3f61e7f MD |
753 | } |
754 | ||
755 | ret = channel_backend_init(&chan->backend, name, config, | |
1d498196 | 756 | subbuf_size, num_subbuf, handle); |
852c2936 | 757 | if (ret) |
1d498196 | 758 | goto error_backend_init; |
852c2936 | 759 | |
03d2d293 | 760 | chan->handle = handle; |
852c2936 | 761 | chan->commit_count_mask = (~0UL >> chan->backend.num_subbuf_order); |
852c2936 | 762 | |
34a91bdb MD |
763 | chan->switch_timer_interval = switch_timer_interval; |
764 | chan->read_timer_interval = read_timer_interval; | |
03d2d293 | 765 | lib_ring_buffer_channel_switch_timer_start(chan); |
34a91bdb | 766 | lib_ring_buffer_channel_read_timer_start(chan); |
852c2936 | 767 | |
431d5cf0 | 768 | return handle; |
852c2936 | 769 | |
1d498196 MD |
770 | error_backend_init: |
771 | error_append: | |
772 | shm_object_table_destroy(handle->table); | |
773 | error_table_alloc: | |
431d5cf0 | 774 | free(handle); |
852c2936 MD |
775 | return NULL; |
776 | } | |
852c2936 | 777 | |
74d81a6c | 778 | struct lttng_ust_shm_handle *channel_handle_create(void *data, |
ff0f5728 MD |
779 | uint64_t memory_map_size, |
780 | int wakeup_fd) | |
193183fb | 781 | { |
38fae1d3 | 782 | struct lttng_ust_shm_handle *handle; |
193183fb MD |
783 | struct shm_object *object; |
784 | ||
38fae1d3 | 785 | handle = zmalloc(sizeof(struct lttng_ust_shm_handle)); |
193183fb MD |
786 | if (!handle) |
787 | return NULL; | |
788 | ||
789 | /* Allocate table for channel + per-cpu buffers */ | |
790 | handle->table = shm_object_table_create(1 + num_possible_cpus()); | |
791 | if (!handle->table) | |
792 | goto error_table_alloc; | |
793 | /* Add channel object */ | |
74d81a6c | 794 | object = shm_object_table_append_mem(handle->table, data, |
ff0f5728 | 795 | memory_map_size, wakeup_fd); |
193183fb MD |
796 | if (!object) |
797 | goto error_table_object; | |
57773204 MD |
798 | /* struct channel is at object 0, offset 0 (hardcoded) */ |
799 | handle->chan._ref.index = 0; | |
800 | handle->chan._ref.offset = 0; | |
193183fb MD |
801 | return handle; |
802 | ||
803 | error_table_object: | |
804 | shm_object_table_destroy(handle->table); | |
805 | error_table_alloc: | |
806 | free(handle); | |
807 | return NULL; | |
808 | } | |
809 | ||
38fae1d3 | 810 | int channel_handle_add_stream(struct lttng_ust_shm_handle *handle, |
74d81a6c MD |
811 | int shm_fd, int wakeup_fd, uint32_t stream_nr, |
812 | uint64_t memory_map_size) | |
193183fb MD |
813 | { |
814 | struct shm_object *object; | |
815 | ||
816 | /* Add stream object */ | |
74d81a6c MD |
817 | object = shm_object_table_append_shm(handle->table, |
818 | shm_fd, wakeup_fd, stream_nr, | |
819 | memory_map_size); | |
193183fb | 820 | if (!object) |
74d81a6c | 821 | return -EINVAL; |
193183fb MD |
822 | return 0; |
823 | } | |
824 | ||
74d81a6c MD |
825 | unsigned int channel_handle_get_nr_streams(struct lttng_ust_shm_handle *handle) |
826 | { | |
827 | assert(handle->table); | |
828 | return handle->table->allocated_len - 1; | |
829 | } | |
830 | ||
852c2936 | 831 | static |
74d81a6c | 832 | void channel_release(struct channel *chan, struct lttng_ust_shm_handle *handle) |
852c2936 | 833 | { |
74d81a6c | 834 | channel_free(chan, handle); |
852c2936 MD |
835 | } |
836 | ||
837 | /** | |
838 | * channel_destroy - Finalize, wait for q.s. and destroy channel. | |
839 | * @chan: channel to destroy | |
840 | * | |
841 | * Holds cpu hotplug. | |
431d5cf0 MD |
842 | * Call "destroy" callback, finalize channels, decrement the channel |
843 | * reference count. Note that when readers have completed data | |
844 | * consumption of finalized channels, get_subbuf() will return -ENODATA. | |
a3f61e7f | 845 | * They should release their handle at that point. |
852c2936 | 846 | */ |
a3f61e7f | 847 | void channel_destroy(struct channel *chan, struct lttng_ust_shm_handle *handle, |
74d81a6c | 848 | int consumer) |
852c2936 | 849 | { |
74d81a6c MD |
850 | if (consumer) { |
851 | /* | |
852 | * Note: the consumer takes care of finalizing and | |
853 | * switching the buffers. | |
854 | */ | |
855 | channel_unregister_notifiers(chan, handle); | |
3d0ef9f6 MD |
856 | /* |
857 | * The consumer prints errors. | |
858 | */ | |
859 | channel_print_errors(chan, handle); | |
824f40b8 MD |
860 | } |
861 | ||
431d5cf0 MD |
862 | /* |
863 | * sessiond/consumer are keeping a reference on the shm file | |
864 | * descriptor directly. No need to refcount. | |
865 | */ | |
74d81a6c | 866 | channel_release(chan, handle); |
a3f61e7f | 867 | return; |
852c2936 | 868 | } |
852c2936 | 869 | |
4cfec15c MD |
870 | struct lttng_ust_lib_ring_buffer *channel_get_ring_buffer( |
871 | const struct lttng_ust_lib_ring_buffer_config *config, | |
1d498196 | 872 | struct channel *chan, int cpu, |
38fae1d3 | 873 | struct lttng_ust_shm_handle *handle, |
74d81a6c MD |
874 | int *shm_fd, int *wait_fd, |
875 | int *wakeup_fd, | |
876 | uint64_t *memory_map_size) | |
852c2936 | 877 | { |
381c0f1e MD |
878 | struct shm_ref *ref; |
879 | ||
880 | if (config->alloc == RING_BUFFER_ALLOC_GLOBAL) { | |
74d81a6c | 881 | cpu = 0; |
381c0f1e | 882 | } else { |
e095d803 MD |
883 | if (cpu >= num_possible_cpus()) |
884 | return NULL; | |
381c0f1e | 885 | } |
74d81a6c MD |
886 | ref = &chan->backend.buf[cpu].shmp._ref; |
887 | *shm_fd = shm_get_shm_fd(handle, ref); | |
888 | *wait_fd = shm_get_wait_fd(handle, ref); | |
889 | *wakeup_fd = shm_get_wakeup_fd(handle, ref); | |
890 | if (shm_get_shm_size(handle, ref, memory_map_size)) | |
891 | return NULL; | |
892 | return shmp(handle, chan->backend.buf[cpu].shmp); | |
852c2936 | 893 | } |
852c2936 | 894 | |
ff0f5728 MD |
895 | int ring_buffer_channel_close_wait_fd(const struct lttng_ust_lib_ring_buffer_config *config, |
896 | struct channel *chan, | |
897 | struct lttng_ust_shm_handle *handle) | |
898 | { | |
899 | struct shm_ref *ref; | |
900 | ||
901 | ref = &handle->chan._ref; | |
902 | return shm_close_wait_fd(handle, ref); | |
903 | } | |
904 | ||
905 | int ring_buffer_channel_close_wakeup_fd(const struct lttng_ust_lib_ring_buffer_config *config, | |
906 | struct channel *chan, | |
907 | struct lttng_ust_shm_handle *handle) | |
908 | { | |
909 | struct shm_ref *ref; | |
910 | ||
911 | ref = &handle->chan._ref; | |
912 | return shm_close_wakeup_fd(handle, ref); | |
913 | } | |
914 | ||
915 | int ring_buffer_stream_close_wait_fd(const struct lttng_ust_lib_ring_buffer_config *config, | |
74d81a6c MD |
916 | struct channel *chan, |
917 | struct lttng_ust_shm_handle *handle, | |
918 | int cpu) | |
852c2936 | 919 | { |
74d81a6c MD |
920 | struct shm_ref *ref; |
921 | ||
922 | if (config->alloc == RING_BUFFER_ALLOC_GLOBAL) { | |
923 | cpu = 0; | |
924 | } else { | |
925 | if (cpu >= num_possible_cpus()) | |
926 | return -EINVAL; | |
824f40b8 | 927 | } |
74d81a6c MD |
928 | ref = &chan->backend.buf[cpu].shmp._ref; |
929 | return shm_close_wait_fd(handle, ref); | |
930 | } | |
931 | ||
ff0f5728 | 932 | int ring_buffer_stream_close_wakeup_fd(const struct lttng_ust_lib_ring_buffer_config *config, |
74d81a6c MD |
933 | struct channel *chan, |
934 | struct lttng_ust_shm_handle *handle, | |
935 | int cpu) | |
936 | { | |
937 | struct shm_ref *ref; | |
cb7378b3 | 938 | int ret; |
74d81a6c MD |
939 | |
940 | if (config->alloc == RING_BUFFER_ALLOC_GLOBAL) { | |
941 | cpu = 0; | |
942 | } else { | |
943 | if (cpu >= num_possible_cpus()) | |
944 | return -EINVAL; | |
945 | } | |
946 | ref = &chan->backend.buf[cpu].shmp._ref; | |
cb7378b3 MD |
947 | pthread_mutex_lock(&wakeup_fd_mutex); |
948 | ret = shm_close_wakeup_fd(handle, ref); | |
949 | pthread_mutex_unlock(&wakeup_fd_mutex); | |
950 | return ret; | |
74d81a6c MD |
951 | } |
952 | ||
953 | int lib_ring_buffer_open_read(struct lttng_ust_lib_ring_buffer *buf, | |
954 | struct lttng_ust_shm_handle *handle) | |
955 | { | |
a6352fd4 | 956 | if (uatomic_cmpxchg(&buf->active_readers, 0, 1) != 0) |
852c2936 | 957 | return -EBUSY; |
a6352fd4 | 958 | cmm_smp_mb(); |
852c2936 MD |
959 | return 0; |
960 | } | |
852c2936 | 961 | |
4cfec15c | 962 | void lib_ring_buffer_release_read(struct lttng_ust_lib_ring_buffer *buf, |
74d81a6c | 963 | struct lttng_ust_shm_handle *handle) |
852c2936 | 964 | { |
1d498196 | 965 | struct channel *chan = shmp(handle, buf->backend.chan); |
852c2936 | 966 | |
a6352fd4 MD |
967 | CHAN_WARN_ON(chan, uatomic_read(&buf->active_readers) != 1); |
968 | cmm_smp_mb(); | |
969 | uatomic_dec(&buf->active_readers); | |
852c2936 MD |
970 | } |
971 | ||
972 | /** | |
973 | * lib_ring_buffer_snapshot - save subbuffer position snapshot (for read) | |
974 | * @buf: ring buffer | |
975 | * @consumed: consumed count indicating the position where to read | |
976 | * @produced: produced count, indicates position when to stop reading | |
977 | * | |
978 | * Returns -ENODATA if buffer is finalized, -EAGAIN if there is currently no | |
979 | * data to read at consumed position, or 0 if the get operation succeeds. | |
852c2936 MD |
980 | */ |
981 | ||
4cfec15c | 982 | int lib_ring_buffer_snapshot(struct lttng_ust_lib_ring_buffer *buf, |
1d498196 | 983 | unsigned long *consumed, unsigned long *produced, |
38fae1d3 | 984 | struct lttng_ust_shm_handle *handle) |
852c2936 | 985 | { |
1d498196 | 986 | struct channel *chan = shmp(handle, buf->backend.chan); |
4cfec15c | 987 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
852c2936 MD |
988 | unsigned long consumed_cur, write_offset; |
989 | int finalized; | |
990 | ||
14641deb | 991 | finalized = CMM_ACCESS_ONCE(buf->finalized); |
852c2936 MD |
992 | /* |
993 | * Read finalized before counters. | |
994 | */ | |
a6352fd4 MD |
995 | cmm_smp_rmb(); |
996 | consumed_cur = uatomic_read(&buf->consumed); | |
852c2936 MD |
997 | /* |
998 | * No need to issue a memory barrier between consumed count read and | |
999 | * write offset read, because consumed count can only change | |
1000 | * concurrently in overwrite mode, and we keep a sequence counter | |
1001 | * identifier derived from the write offset to check we are getting | |
1002 | * the same sub-buffer we are expecting (the sub-buffers are atomically | |
1003 | * "tagged" upon writes, tags are checked upon read). | |
1004 | */ | |
1005 | write_offset = v_read(config, &buf->offset); | |
1006 | ||
1007 | /* | |
1008 | * Check that we are not about to read the same subbuffer in | |
1009 | * which the writer head is. | |
1010 | */ | |
1011 | if (subbuf_trunc(write_offset, chan) - subbuf_trunc(consumed_cur, chan) | |
1012 | == 0) | |
1013 | goto nodata; | |
1014 | ||
1015 | *consumed = consumed_cur; | |
1016 | *produced = subbuf_trunc(write_offset, chan); | |
1017 | ||
1018 | return 0; | |
1019 | ||
1020 | nodata: | |
1021 | /* | |
1022 | * The memory barriers __wait_event()/wake_up_interruptible() take care | |
1023 | * of "raw_spin_is_locked" memory ordering. | |
1024 | */ | |
1025 | if (finalized) | |
1026 | return -ENODATA; | |
852c2936 MD |
1027 | else |
1028 | return -EAGAIN; | |
1029 | } | |
852c2936 MD |
1030 | |
1031 | /** | |
d1a996f5 | 1032 | * lib_ring_buffer_move_consumer - move consumed counter forward |
852c2936 MD |
1033 | * @buf: ring buffer |
1034 | * @consumed_new: new consumed count value | |
1035 | */ | |
4cfec15c | 1036 | void lib_ring_buffer_move_consumer(struct lttng_ust_lib_ring_buffer *buf, |
1d498196 | 1037 | unsigned long consumed_new, |
38fae1d3 | 1038 | struct lttng_ust_shm_handle *handle) |
852c2936 | 1039 | { |
4cfec15c | 1040 | struct lttng_ust_lib_ring_buffer_backend *bufb = &buf->backend; |
1d498196 | 1041 | struct channel *chan = shmp(handle, bufb->chan); |
852c2936 MD |
1042 | unsigned long consumed; |
1043 | ||
74d81a6c | 1044 | CHAN_WARN_ON(chan, uatomic_read(&buf->active_readers) != 1); |
852c2936 MD |
1045 | |
1046 | /* | |
1047 | * Only push the consumed value forward. | |
1048 | * If the consumed cmpxchg fails, this is because we have been pushed by | |
1049 | * the writer in flight recorder mode. | |
1050 | */ | |
a6352fd4 | 1051 | consumed = uatomic_read(&buf->consumed); |
852c2936 | 1052 | while ((long) consumed - (long) consumed_new < 0) |
a6352fd4 MD |
1053 | consumed = uatomic_cmpxchg(&buf->consumed, consumed, |
1054 | consumed_new); | |
852c2936 | 1055 | } |
852c2936 MD |
1056 | |
1057 | /** | |
1058 | * lib_ring_buffer_get_subbuf - get exclusive access to subbuffer for reading | |
1059 | * @buf: ring buffer | |
1060 | * @consumed: consumed count indicating the position where to read | |
1061 | * | |
1062 | * Returns -ENODATA if buffer is finalized, -EAGAIN if there is currently no | |
1063 | * data to read at consumed position, or 0 if the get operation succeeds. | |
852c2936 | 1064 | */ |
4cfec15c | 1065 | int lib_ring_buffer_get_subbuf(struct lttng_ust_lib_ring_buffer *buf, |
1d498196 | 1066 | unsigned long consumed, |
38fae1d3 | 1067 | struct lttng_ust_shm_handle *handle) |
852c2936 | 1068 | { |
1d498196 | 1069 | struct channel *chan = shmp(handle, buf->backend.chan); |
4cfec15c | 1070 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
852c2936 | 1071 | unsigned long consumed_cur, consumed_idx, commit_count, write_offset; |
57ebc611 | 1072 | int ret, finalized, nr_retry = LTTNG_UST_RING_BUFFER_GET_RETRY; |
852c2936 MD |
1073 | |
1074 | retry: | |
14641deb | 1075 | finalized = CMM_ACCESS_ONCE(buf->finalized); |
852c2936 MD |
1076 | /* |
1077 | * Read finalized before counters. | |
1078 | */ | |
a6352fd4 MD |
1079 | cmm_smp_rmb(); |
1080 | consumed_cur = uatomic_read(&buf->consumed); | |
852c2936 | 1081 | consumed_idx = subbuf_index(consumed, chan); |
4746ae29 | 1082 | commit_count = v_read(config, &shmp_index(handle, buf->commit_cold, consumed_idx)->cc_sb); |
852c2936 MD |
1083 | /* |
1084 | * Make sure we read the commit count before reading the buffer | |
1085 | * data and the write offset. Correct consumed offset ordering | |
1086 | * wrt commit count is insured by the use of cmpxchg to update | |
1087 | * the consumed offset. | |
852c2936 | 1088 | */ |
a6352fd4 MD |
1089 | /* |
1090 | * Local rmb to match the remote wmb to read the commit count | |
1091 | * before the buffer data and the write offset. | |
1092 | */ | |
1093 | cmm_smp_rmb(); | |
852c2936 MD |
1094 | |
1095 | write_offset = v_read(config, &buf->offset); | |
1096 | ||
1097 | /* | |
1098 | * Check that the buffer we are getting is after or at consumed_cur | |
1099 | * position. | |
1100 | */ | |
1101 | if ((long) subbuf_trunc(consumed, chan) | |
1102 | - (long) subbuf_trunc(consumed_cur, chan) < 0) | |
1103 | goto nodata; | |
1104 | ||
1105 | /* | |
1106 | * Check that the subbuffer we are trying to consume has been | |
57ebc611 MD |
1107 | * already fully committed. There are a few causes that can make |
1108 | * this unavailability situation occur: | |
1109 | * | |
1110 | * Temporary (short-term) situation: | |
1111 | * - Application is running on a different CPU, between reserve | |
1112 | * and commit ring buffer operations, | |
1113 | * - Application is preempted between reserve and commit ring | |
1114 | * buffer operations, | |
1115 | * | |
1116 | * Long-term situation: | |
1117 | * - Application is stopped (SIGSTOP) between reserve and commit | |
1118 | * ring buffer operations. Could eventually be resumed by | |
1119 | * SIGCONT. | |
1120 | * - Application is killed (SIGTERM, SIGINT, SIGKILL) between | |
1121 | * reserve and commit ring buffer operation. | |
1122 | * | |
1123 | * From a consumer perspective, handling short-term | |
1124 | * unavailability situations is performed by retrying a few | |
1125 | * times after a delay. Handling long-term unavailability | |
1126 | * situations is handled by failing to get the sub-buffer. | |
1127 | * | |
1128 | * In all of those situations, if the application is taking a | |
1129 | * long time to perform its commit after ring buffer space | |
1130 | * reservation, we can end up in a situation where the producer | |
1131 | * will fill the ring buffer and try to write into the same | |
1132 | * sub-buffer again (which has a missing commit). This is | |
1133 | * handled by the producer in the sub-buffer switch handling | |
1134 | * code of the reserve routine by detecting unbalanced | |
1135 | * reserve/commit counters and discarding all further events | |
1136 | * until the situation is resolved in those situations. Two | |
1137 | * scenarios can occur: | |
1138 | * | |
1139 | * 1) The application causing the reserve/commit counters to be | |
1140 | * unbalanced has been terminated. In this situation, all | |
1141 | * further events will be discarded in the buffers, and no | |
1142 | * further buffer data will be readable by the consumer | |
1143 | * daemon. Tearing down the UST tracing session and starting | |
1144 | * anew is a work-around for those situations. Note that this | |
1145 | * only affects per-UID tracing. In per-PID tracing, the | |
1146 | * application vanishes with the termination, and therefore | |
1147 | * no more data needs to be written to the buffers. | |
1148 | * 2) The application causing the unbalance has been delayed for | |
1149 | * a long time, but will eventually try to increment the | |
1150 | * commit counter after eventually writing to the sub-buffer. | |
1151 | * This situation can cause events to be discarded until the | |
1152 | * application resumes its operations. | |
852c2936 MD |
1153 | */ |
1154 | if (((commit_count - chan->backend.subbuf_size) | |
1155 | & chan->commit_count_mask) | |
0bade047 | 1156 | - (buf_trunc(consumed, chan) |
852c2936 | 1157 | >> chan->backend.num_subbuf_order) |
57ebc611 MD |
1158 | != 0) { |
1159 | if (nr_retry-- > 0) { | |
1160 | if (nr_retry <= (LTTNG_UST_RING_BUFFER_GET_RETRY >> 1)) | |
1161 | (void) poll(NULL, 0, LTTNG_UST_RING_BUFFER_RETRY_DELAY_MS); | |
1162 | goto retry; | |
1163 | } else { | |
1164 | goto nodata; | |
1165 | } | |
1166 | } | |
852c2936 MD |
1167 | |
1168 | /* | |
1169 | * Check that we are not about to read the same subbuffer in | |
1170 | * which the writer head is. | |
1171 | */ | |
0bade047 | 1172 | if (subbuf_trunc(write_offset, chan) - subbuf_trunc(consumed, chan) |
852c2936 MD |
1173 | == 0) |
1174 | goto nodata; | |
1175 | ||
1176 | /* | |
1177 | * Failure to get the subbuffer causes a busy-loop retry without going | |
1178 | * to a wait queue. These are caused by short-lived race windows where | |
1179 | * the writer is getting access to a subbuffer we were trying to get | |
1180 | * access to. Also checks that the "consumed" buffer count we are | |
1181 | * looking for matches the one contained in the subbuffer id. | |
57ebc611 MD |
1182 | * |
1183 | * The short-lived race window described here can be affected by | |
1184 | * application signals and preemption, thus requiring to bound | |
1185 | * the loop to a maximum number of retry. | |
852c2936 MD |
1186 | */ |
1187 | ret = update_read_sb_index(config, &buf->backend, &chan->backend, | |
1d498196 MD |
1188 | consumed_idx, buf_trunc_val(consumed, chan), |
1189 | handle); | |
57ebc611 MD |
1190 | if (ret) { |
1191 | if (nr_retry-- > 0) { | |
1192 | if (nr_retry <= (LTTNG_UST_RING_BUFFER_GET_RETRY >> 1)) | |
1193 | (void) poll(NULL, 0, LTTNG_UST_RING_BUFFER_RETRY_DELAY_MS); | |
1194 | goto retry; | |
1195 | } else { | |
1196 | goto nodata; | |
1197 | } | |
1198 | } | |
852c2936 MD |
1199 | subbuffer_id_clear_noref(config, &buf->backend.buf_rsb.id); |
1200 | ||
1201 | buf->get_subbuf_consumed = consumed; | |
1202 | buf->get_subbuf = 1; | |
1203 | ||
1204 | return 0; | |
1205 | ||
1206 | nodata: | |
1207 | /* | |
1208 | * The memory barriers __wait_event()/wake_up_interruptible() take care | |
1209 | * of "raw_spin_is_locked" memory ordering. | |
1210 | */ | |
1211 | if (finalized) | |
1212 | return -ENODATA; | |
852c2936 MD |
1213 | else |
1214 | return -EAGAIN; | |
1215 | } | |
852c2936 MD |
1216 | |
1217 | /** | |
1218 | * lib_ring_buffer_put_subbuf - release exclusive subbuffer access | |
1219 | * @buf: ring buffer | |
1220 | */ | |
4cfec15c | 1221 | void lib_ring_buffer_put_subbuf(struct lttng_ust_lib_ring_buffer *buf, |
38fae1d3 | 1222 | struct lttng_ust_shm_handle *handle) |
852c2936 | 1223 | { |
4cfec15c | 1224 | struct lttng_ust_lib_ring_buffer_backend *bufb = &buf->backend; |
1d498196 | 1225 | struct channel *chan = shmp(handle, bufb->chan); |
4cfec15c | 1226 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
852c2936 MD |
1227 | unsigned long read_sb_bindex, consumed_idx, consumed; |
1228 | ||
74d81a6c | 1229 | CHAN_WARN_ON(chan, uatomic_read(&buf->active_readers) != 1); |
852c2936 MD |
1230 | |
1231 | if (!buf->get_subbuf) { | |
1232 | /* | |
1233 | * Reader puts a subbuffer it did not get. | |
1234 | */ | |
1235 | CHAN_WARN_ON(chan, 1); | |
1236 | return; | |
1237 | } | |
1238 | consumed = buf->get_subbuf_consumed; | |
1239 | buf->get_subbuf = 0; | |
1240 | ||
1241 | /* | |
1242 | * Clear the records_unread counter. (overruns counter) | |
1243 | * Can still be non-zero if a file reader simply grabbed the data | |
1244 | * without using iterators. | |
1245 | * Can be below zero if an iterator is used on a snapshot more than | |
1246 | * once. | |
1247 | */ | |
1248 | read_sb_bindex = subbuffer_id_get_index(config, bufb->buf_rsb.id); | |
1249 | v_add(config, v_read(config, | |
4746ae29 | 1250 | &shmp(handle, shmp_index(handle, bufb->array, read_sb_bindex)->shmp)->records_unread), |
852c2936 | 1251 | &bufb->records_read); |
4746ae29 | 1252 | v_set(config, &shmp(handle, shmp_index(handle, bufb->array, read_sb_bindex)->shmp)->records_unread, 0); |
852c2936 MD |
1253 | CHAN_WARN_ON(chan, config->mode == RING_BUFFER_OVERWRITE |
1254 | && subbuffer_id_is_noref(config, bufb->buf_rsb.id)); | |
1255 | subbuffer_id_set_noref(config, &bufb->buf_rsb.id); | |
1256 | ||
1257 | /* | |
1258 | * Exchange the reader subbuffer with the one we put in its place in the | |
1259 | * writer subbuffer table. Expect the original consumed count. If | |
1260 | * update_read_sb_index fails, this is because the writer updated the | |
1261 | * subbuffer concurrently. We should therefore keep the subbuffer we | |
1262 | * currently have: it has become invalid to try reading this sub-buffer | |
1263 | * consumed count value anyway. | |
1264 | */ | |
1265 | consumed_idx = subbuf_index(consumed, chan); | |
1266 | update_read_sb_index(config, &buf->backend, &chan->backend, | |
1d498196 MD |
1267 | consumed_idx, buf_trunc_val(consumed, chan), |
1268 | handle); | |
852c2936 MD |
1269 | /* |
1270 | * update_read_sb_index return value ignored. Don't exchange sub-buffer | |
1271 | * if the writer concurrently updated it. | |
1272 | */ | |
1273 | } | |
852c2936 MD |
1274 | |
1275 | /* | |
1276 | * cons_offset is an iterator on all subbuffer offsets between the reader | |
1277 | * position and the writer position. (inclusive) | |
1278 | */ | |
1279 | static | |
4cfec15c | 1280 | void lib_ring_buffer_print_subbuffer_errors(struct lttng_ust_lib_ring_buffer *buf, |
852c2936 MD |
1281 | struct channel *chan, |
1282 | unsigned long cons_offset, | |
1d498196 | 1283 | int cpu, |
38fae1d3 | 1284 | struct lttng_ust_shm_handle *handle) |
852c2936 | 1285 | { |
4cfec15c | 1286 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
852c2936 MD |
1287 | unsigned long cons_idx, commit_count, commit_count_sb; |
1288 | ||
1289 | cons_idx = subbuf_index(cons_offset, chan); | |
4746ae29 MD |
1290 | commit_count = v_read(config, &shmp_index(handle, buf->commit_hot, cons_idx)->cc); |
1291 | commit_count_sb = v_read(config, &shmp_index(handle, buf->commit_cold, cons_idx)->cc_sb); | |
852c2936 MD |
1292 | |
1293 | if (subbuf_offset(commit_count, chan) != 0) | |
4d3c9523 | 1294 | DBG("ring buffer %s, cpu %d: " |
852c2936 MD |
1295 | "commit count in subbuffer %lu,\n" |
1296 | "expecting multiples of %lu bytes\n" | |
1297 | " [ %lu bytes committed, %lu bytes reader-visible ]\n", | |
1298 | chan->backend.name, cpu, cons_idx, | |
1299 | chan->backend.subbuf_size, | |
1300 | commit_count, commit_count_sb); | |
1301 | ||
4d3c9523 | 1302 | DBG("ring buffer: %s, cpu %d: %lu bytes committed\n", |
852c2936 MD |
1303 | chan->backend.name, cpu, commit_count); |
1304 | } | |
1305 | ||
1306 | static | |
4cfec15c | 1307 | void lib_ring_buffer_print_buffer_errors(struct lttng_ust_lib_ring_buffer *buf, |
852c2936 | 1308 | struct channel *chan, |
1d498196 | 1309 | void *priv, int cpu, |
38fae1d3 | 1310 | struct lttng_ust_shm_handle *handle) |
852c2936 | 1311 | { |
4cfec15c | 1312 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
852c2936 MD |
1313 | unsigned long write_offset, cons_offset; |
1314 | ||
852c2936 MD |
1315 | /* |
1316 | * No need to order commit_count, write_offset and cons_offset reads | |
1317 | * because we execute at teardown when no more writer nor reader | |
1318 | * references are left. | |
1319 | */ | |
1320 | write_offset = v_read(config, &buf->offset); | |
a6352fd4 | 1321 | cons_offset = uatomic_read(&buf->consumed); |
852c2936 | 1322 | if (write_offset != cons_offset) |
4d3c9523 | 1323 | DBG("ring buffer %s, cpu %d: " |
852c2936 MD |
1324 | "non-consumed data\n" |
1325 | " [ %lu bytes written, %lu bytes read ]\n", | |
1326 | chan->backend.name, cpu, write_offset, cons_offset); | |
1327 | ||
a6352fd4 | 1328 | for (cons_offset = uatomic_read(&buf->consumed); |
852c2936 MD |
1329 | (long) (subbuf_trunc((unsigned long) v_read(config, &buf->offset), |
1330 | chan) | |
1331 | - cons_offset) > 0; | |
1332 | cons_offset = subbuf_align(cons_offset, chan)) | |
1333 | lib_ring_buffer_print_subbuffer_errors(buf, chan, cons_offset, | |
1d498196 | 1334 | cpu, handle); |
852c2936 MD |
1335 | } |
1336 | ||
1337 | static | |
1338 | void lib_ring_buffer_print_errors(struct channel *chan, | |
009769ca MD |
1339 | struct lttng_ust_lib_ring_buffer *buf, int cpu, |
1340 | struct lttng_ust_shm_handle *handle) | |
852c2936 | 1341 | { |
4cfec15c | 1342 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
a3f61e7f | 1343 | void *priv = channel_get_private(chan); |
852c2936 | 1344 | |
a1360615 MD |
1345 | if (!strcmp(chan->backend.name, "relay-metadata-mmap")) { |
1346 | DBG("ring buffer %s: %lu records written, " | |
1347 | "%lu records overrun\n", | |
1348 | chan->backend.name, | |
1349 | v_read(config, &buf->records_count), | |
1350 | v_read(config, &buf->records_overrun)); | |
1351 | } else { | |
1352 | DBG("ring buffer %s, cpu %d: %lu records written, " | |
1353 | "%lu records overrun\n", | |
1354 | chan->backend.name, cpu, | |
1355 | v_read(config, &buf->records_count), | |
1356 | v_read(config, &buf->records_overrun)); | |
1357 | ||
1358 | if (v_read(config, &buf->records_lost_full) | |
1359 | || v_read(config, &buf->records_lost_wrap) | |
1360 | || v_read(config, &buf->records_lost_big)) | |
1361 | DBG("ring buffer %s, cpu %d: records were lost. Caused by:\n" | |
1362 | " [ %lu buffer full, %lu nest buffer wrap-around, " | |
1363 | "%lu event too big ]\n", | |
1364 | chan->backend.name, cpu, | |
1365 | v_read(config, &buf->records_lost_full), | |
1366 | v_read(config, &buf->records_lost_wrap), | |
1367 | v_read(config, &buf->records_lost_big)); | |
1368 | } | |
1d498196 | 1369 | lib_ring_buffer_print_buffer_errors(buf, chan, priv, cpu, handle); |
852c2936 MD |
1370 | } |
1371 | ||
1372 | /* | |
1373 | * lib_ring_buffer_switch_old_start: Populate old subbuffer header. | |
1374 | * | |
1375 | * Only executed when the buffer is finalized, in SWITCH_FLUSH. | |
1376 | */ | |
1377 | static | |
4cfec15c | 1378 | void lib_ring_buffer_switch_old_start(struct lttng_ust_lib_ring_buffer *buf, |
852c2936 MD |
1379 | struct channel *chan, |
1380 | struct switch_offsets *offsets, | |
2fed87ae | 1381 | uint64_t tsc, |
38fae1d3 | 1382 | struct lttng_ust_shm_handle *handle) |
852c2936 | 1383 | { |
4cfec15c | 1384 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
852c2936 MD |
1385 | unsigned long oldidx = subbuf_index(offsets->old, chan); |
1386 | unsigned long commit_count; | |
1387 | ||
1d498196 | 1388 | config->cb.buffer_begin(buf, tsc, oldidx, handle); |
852c2936 MD |
1389 | |
1390 | /* | |
1391 | * Order all writes to buffer before the commit count update that will | |
1392 | * determine that the subbuffer is full. | |
1393 | */ | |
a6352fd4 | 1394 | cmm_smp_wmb(); |
852c2936 | 1395 | v_add(config, config->cb.subbuffer_header_size(), |
4746ae29 MD |
1396 | &shmp_index(handle, buf->commit_hot, oldidx)->cc); |
1397 | commit_count = v_read(config, &shmp_index(handle, buf->commit_hot, oldidx)->cc); | |
852c2936 MD |
1398 | /* Check if the written buffer has to be delivered */ |
1399 | lib_ring_buffer_check_deliver(config, buf, chan, offsets->old, | |
1b7b0501 | 1400 | commit_count, oldidx, handle, tsc); |
852c2936 | 1401 | lib_ring_buffer_write_commit_counter(config, buf, chan, oldidx, |
80249235 MD |
1402 | offsets->old + config->cb.subbuffer_header_size(), |
1403 | commit_count, handle); | |
852c2936 MD |
1404 | } |
1405 | ||
1406 | /* | |
1407 | * lib_ring_buffer_switch_old_end: switch old subbuffer | |
1408 | * | |
1409 | * Note : offset_old should never be 0 here. It is ok, because we never perform | |
1410 | * buffer switch on an empty subbuffer in SWITCH_ACTIVE mode. The caller | |
1411 | * increments the offset_old value when doing a SWITCH_FLUSH on an empty | |
1412 | * subbuffer. | |
1413 | */ | |
1414 | static | |
4cfec15c | 1415 | void lib_ring_buffer_switch_old_end(struct lttng_ust_lib_ring_buffer *buf, |
852c2936 MD |
1416 | struct channel *chan, |
1417 | struct switch_offsets *offsets, | |
2fed87ae | 1418 | uint64_t tsc, |
38fae1d3 | 1419 | struct lttng_ust_shm_handle *handle) |
852c2936 | 1420 | { |
4cfec15c | 1421 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
852c2936 MD |
1422 | unsigned long oldidx = subbuf_index(offsets->old - 1, chan); |
1423 | unsigned long commit_count, padding_size, data_size; | |
1424 | ||
1425 | data_size = subbuf_offset(offsets->old - 1, chan) + 1; | |
1426 | padding_size = chan->backend.subbuf_size - data_size; | |
1d498196 MD |
1427 | subbuffer_set_data_size(config, &buf->backend, oldidx, data_size, |
1428 | handle); | |
852c2936 MD |
1429 | |
1430 | /* | |
1431 | * Order all writes to buffer before the commit count update that will | |
1432 | * determine that the subbuffer is full. | |
1433 | */ | |
a6352fd4 | 1434 | cmm_smp_wmb(); |
4746ae29 MD |
1435 | v_add(config, padding_size, &shmp_index(handle, buf->commit_hot, oldidx)->cc); |
1436 | commit_count = v_read(config, &shmp_index(handle, buf->commit_hot, oldidx)->cc); | |
852c2936 | 1437 | lib_ring_buffer_check_deliver(config, buf, chan, offsets->old - 1, |
1b7b0501 | 1438 | commit_count, oldidx, handle, tsc); |
852c2936 | 1439 | lib_ring_buffer_write_commit_counter(config, buf, chan, oldidx, |
80249235 | 1440 | offsets->old + padding_size, commit_count, handle); |
852c2936 MD |
1441 | } |
1442 | ||
1443 | /* | |
1444 | * lib_ring_buffer_switch_new_start: Populate new subbuffer. | |
1445 | * | |
1446 | * This code can be executed unordered : writers may already have written to the | |
1447 | * sub-buffer before this code gets executed, caution. The commit makes sure | |
1448 | * that this code is executed before the deliver of this sub-buffer. | |
1449 | */ | |
1450 | static | |
4cfec15c | 1451 | void lib_ring_buffer_switch_new_start(struct lttng_ust_lib_ring_buffer *buf, |
852c2936 MD |
1452 | struct channel *chan, |
1453 | struct switch_offsets *offsets, | |
2fed87ae | 1454 | uint64_t tsc, |
38fae1d3 | 1455 | struct lttng_ust_shm_handle *handle) |
852c2936 | 1456 | { |
4cfec15c | 1457 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
852c2936 MD |
1458 | unsigned long beginidx = subbuf_index(offsets->begin, chan); |
1459 | unsigned long commit_count; | |
1460 | ||
1d498196 | 1461 | config->cb.buffer_begin(buf, tsc, beginidx, handle); |
852c2936 MD |
1462 | |
1463 | /* | |
1464 | * Order all writes to buffer before the commit count update that will | |
1465 | * determine that the subbuffer is full. | |
1466 | */ | |
a6352fd4 | 1467 | cmm_smp_wmb(); |
852c2936 | 1468 | v_add(config, config->cb.subbuffer_header_size(), |
4746ae29 MD |
1469 | &shmp_index(handle, buf->commit_hot, beginidx)->cc); |
1470 | commit_count = v_read(config, &shmp_index(handle, buf->commit_hot, beginidx)->cc); | |
852c2936 MD |
1471 | /* Check if the written buffer has to be delivered */ |
1472 | lib_ring_buffer_check_deliver(config, buf, chan, offsets->begin, | |
1b7b0501 | 1473 | commit_count, beginidx, handle, tsc); |
852c2936 | 1474 | lib_ring_buffer_write_commit_counter(config, buf, chan, beginidx, |
80249235 MD |
1475 | offsets->begin + config->cb.subbuffer_header_size(), |
1476 | commit_count, handle); | |
852c2936 MD |
1477 | } |
1478 | ||
1ad21f70 MD |
1479 | /* |
1480 | * lib_ring_buffer_switch_new_end: finish switching current subbuffer | |
1481 | * | |
3962118d MD |
1482 | * Calls subbuffer_set_data_size() to set the data size of the current |
1483 | * sub-buffer. We do not need to perform check_deliver nor commit here, | |
1484 | * since this task will be done by the "commit" of the event for which | |
1485 | * we are currently doing the space reservation. | |
1ad21f70 MD |
1486 | */ |
1487 | static | |
1488 | void lib_ring_buffer_switch_new_end(struct lttng_ust_lib_ring_buffer *buf, | |
1489 | struct channel *chan, | |
1490 | struct switch_offsets *offsets, | |
1491 | uint64_t tsc, | |
1492 | struct lttng_ust_shm_handle *handle) | |
1493 | { | |
1494 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; | |
3962118d | 1495 | unsigned long endidx, data_size; |
1ad21f70 | 1496 | |
3962118d | 1497 | endidx = subbuf_index(offsets->end - 1, chan); |
1ad21f70 | 1498 | data_size = subbuf_offset(offsets->end - 1, chan) + 1; |
1ad21f70 MD |
1499 | subbuffer_set_data_size(config, &buf->backend, endidx, data_size, |
1500 | handle); | |
1ad21f70 MD |
1501 | } |
1502 | ||
852c2936 MD |
1503 | /* |
1504 | * Returns : | |
1505 | * 0 if ok | |
1506 | * !0 if execution must be aborted. | |
1507 | */ | |
1508 | static | |
1509 | int lib_ring_buffer_try_switch_slow(enum switch_mode mode, | |
4cfec15c | 1510 | struct lttng_ust_lib_ring_buffer *buf, |
852c2936 MD |
1511 | struct channel *chan, |
1512 | struct switch_offsets *offsets, | |
2dac206d MD |
1513 | uint64_t *tsc, |
1514 | struct lttng_ust_shm_handle *handle) | |
852c2936 | 1515 | { |
4cfec15c | 1516 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
2dac206d | 1517 | unsigned long off, reserve_commit_diff; |
852c2936 MD |
1518 | |
1519 | offsets->begin = v_read(config, &buf->offset); | |
1520 | offsets->old = offsets->begin; | |
1521 | offsets->switch_old_start = 0; | |
1522 | off = subbuf_offset(offsets->begin, chan); | |
1523 | ||
1524 | *tsc = config->cb.ring_buffer_clock_read(chan); | |
1525 | ||
1526 | /* | |
1527 | * Ensure we flush the header of an empty subbuffer when doing the | |
1528 | * finalize (SWITCH_FLUSH). This ensures that we end up knowing the | |
1529 | * total data gathering duration even if there were no records saved | |
1530 | * after the last buffer switch. | |
1531 | * In SWITCH_ACTIVE mode, switch the buffer when it contains events. | |
1532 | * SWITCH_ACTIVE only flushes the current subbuffer, dealing with end of | |
1533 | * subbuffer header as appropriate. | |
1534 | * The next record that reserves space will be responsible for | |
1535 | * populating the following subbuffer header. We choose not to populate | |
1536 | * the next subbuffer header here because we want to be able to use | |
a6352fd4 MD |
1537 | * SWITCH_ACTIVE for periodical buffer flush, which must |
1538 | * guarantee that all the buffer content (records and header | |
1539 | * timestamps) are visible to the reader. This is required for | |
1540 | * quiescence guarantees for the fusion merge. | |
852c2936 | 1541 | */ |
2dac206d MD |
1542 | if (mode != SWITCH_FLUSH && !off) |
1543 | return -1; /* we do not have to switch : buffer is empty */ | |
1544 | ||
1545 | if (caa_unlikely(off == 0)) { | |
1546 | unsigned long sb_index, commit_count; | |
1547 | ||
1548 | /* | |
1549 | * We are performing a SWITCH_FLUSH. At this stage, there are no | |
1550 | * concurrent writes into the buffer. | |
1551 | * | |
1552 | * The client does not save any header information. Don't | |
1553 | * switch empty subbuffer on finalize, because it is invalid to | |
1554 | * deliver a completely empty subbuffer. | |
1555 | */ | |
1556 | if (!config->cb.subbuffer_header_size()) | |
1557 | return -1; | |
1558 | ||
1559 | /* Test new buffer integrity */ | |
1560 | sb_index = subbuf_index(offsets->begin, chan); | |
1561 | commit_count = v_read(config, | |
1562 | &shmp_index(handle, buf->commit_cold, | |
1563 | sb_index)->cc_sb); | |
1564 | reserve_commit_diff = | |
1565 | (buf_trunc(offsets->begin, chan) | |
1566 | >> chan->backend.num_subbuf_order) | |
1567 | - (commit_count & chan->commit_count_mask); | |
1568 | if (caa_likely(reserve_commit_diff == 0)) { | |
1569 | /* Next subbuffer not being written to. */ | |
1570 | if (caa_unlikely(config->mode != RING_BUFFER_OVERWRITE && | |
1571 | subbuf_trunc(offsets->begin, chan) | |
1572 | - subbuf_trunc((unsigned long) | |
1573 | uatomic_read(&buf->consumed), chan) | |
1574 | >= chan->backend.buf_size)) { | |
1575 | /* | |
1576 | * We do not overwrite non consumed buffers | |
1577 | * and we are full : don't switch. | |
1578 | */ | |
852c2936 | 1579 | return -1; |
2dac206d MD |
1580 | } else { |
1581 | /* | |
1582 | * Next subbuffer not being written to, and we | |
1583 | * are either in overwrite mode or the buffer is | |
1584 | * not full. It's safe to write in this new | |
1585 | * subbuffer. | |
1586 | */ | |
1587 | } | |
1588 | } else { | |
852c2936 | 1589 | /* |
2dac206d MD |
1590 | * Next subbuffer reserve offset does not match the |
1591 | * commit offset. Don't perform switch in | |
1592 | * producer-consumer and overwrite mode. Caused by | |
1593 | * either a writer OOPS or too many nested writes over a | |
1594 | * reserve/commit pair. | |
852c2936 | 1595 | */ |
2dac206d | 1596 | return -1; |
852c2936 | 1597 | } |
2dac206d MD |
1598 | |
1599 | /* | |
1600 | * Need to write the subbuffer start header on finalize. | |
1601 | */ | |
1602 | offsets->switch_old_start = 1; | |
1603 | } | |
1604 | offsets->begin = subbuf_align(offsets->begin, chan); | |
852c2936 MD |
1605 | /* Note: old points to the next subbuf at offset 0 */ |
1606 | offsets->end = offsets->begin; | |
1607 | return 0; | |
1608 | } | |
1609 | ||
1610 | /* | |
1611 | * Force a sub-buffer switch. This operation is completely reentrant : can be | |
1612 | * called while tracing is active with absolutely no lock held. | |
1613 | * | |
1614 | * Note, however, that as a v_cmpxchg is used for some atomic | |
1615 | * operations, this function must be called from the CPU which owns the buffer | |
1616 | * for a ACTIVE flush. | |
1617 | */ | |
4cfec15c | 1618 | void lib_ring_buffer_switch_slow(struct lttng_ust_lib_ring_buffer *buf, enum switch_mode mode, |
38fae1d3 | 1619 | struct lttng_ust_shm_handle *handle) |
852c2936 | 1620 | { |
1d498196 | 1621 | struct channel *chan = shmp(handle, buf->backend.chan); |
4cfec15c | 1622 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
852c2936 MD |
1623 | struct switch_offsets offsets; |
1624 | unsigned long oldidx; | |
2fed87ae | 1625 | uint64_t tsc; |
852c2936 MD |
1626 | |
1627 | offsets.size = 0; | |
1628 | ||
1629 | /* | |
1630 | * Perform retryable operations. | |
1631 | */ | |
1632 | do { | |
1633 | if (lib_ring_buffer_try_switch_slow(mode, buf, chan, &offsets, | |
2dac206d | 1634 | &tsc, handle)) |
852c2936 MD |
1635 | return; /* Switch not needed */ |
1636 | } while (v_cmpxchg(config, &buf->offset, offsets.old, offsets.end) | |
1637 | != offsets.old); | |
1638 | ||
1639 | /* | |
1640 | * Atomically update last_tsc. This update races against concurrent | |
1641 | * atomic updates, but the race will always cause supplementary full TSC | |
1642 | * records, never the opposite (missing a full TSC record when it would | |
1643 | * be needed). | |
1644 | */ | |
1645 | save_last_tsc(config, buf, tsc); | |
1646 | ||
1647 | /* | |
1648 | * Push the reader if necessary | |
1649 | */ | |
1650 | lib_ring_buffer_reserve_push_reader(buf, chan, offsets.old); | |
1651 | ||
1652 | oldidx = subbuf_index(offsets.old, chan); | |
1d498196 | 1653 | lib_ring_buffer_clear_noref(config, &buf->backend, oldidx, handle); |
852c2936 MD |
1654 | |
1655 | /* | |
1656 | * May need to populate header start on SWITCH_FLUSH. | |
1657 | */ | |
1658 | if (offsets.switch_old_start) { | |
1d498196 | 1659 | lib_ring_buffer_switch_old_start(buf, chan, &offsets, tsc, handle); |
852c2936 MD |
1660 | offsets.old += config->cb.subbuffer_header_size(); |
1661 | } | |
1662 | ||
1663 | /* | |
1664 | * Switch old subbuffer. | |
1665 | */ | |
1d498196 | 1666 | lib_ring_buffer_switch_old_end(buf, chan, &offsets, tsc, handle); |
852c2936 | 1667 | } |
852c2936 MD |
1668 | |
1669 | /* | |
1670 | * Returns : | |
1671 | * 0 if ok | |
1672 | * -ENOSPC if event size is too large for packet. | |
1673 | * -ENOBUFS if there is currently not enough space in buffer for the event. | |
1674 | * -EIO if data cannot be written into the buffer for any other reason. | |
1675 | */ | |
1676 | static | |
4cfec15c | 1677 | int lib_ring_buffer_try_reserve_slow(struct lttng_ust_lib_ring_buffer *buf, |
852c2936 MD |
1678 | struct channel *chan, |
1679 | struct switch_offsets *offsets, | |
4cfec15c | 1680 | struct lttng_ust_lib_ring_buffer_ctx *ctx) |
852c2936 | 1681 | { |
4cfec15c | 1682 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
38fae1d3 | 1683 | struct lttng_ust_shm_handle *handle = ctx->handle; |
e185cf4b | 1684 | unsigned long reserve_commit_diff, offset_cmp; |
852c2936 | 1685 | |
e185cf4b MD |
1686 | retry: |
1687 | offsets->begin = offset_cmp = v_read(config, &buf->offset); | |
852c2936 MD |
1688 | offsets->old = offsets->begin; |
1689 | offsets->switch_new_start = 0; | |
1ad21f70 | 1690 | offsets->switch_new_end = 0; |
852c2936 MD |
1691 | offsets->switch_old_end = 0; |
1692 | offsets->pre_header_padding = 0; | |
1693 | ||
1694 | ctx->tsc = config->cb.ring_buffer_clock_read(chan); | |
1695 | if ((int64_t) ctx->tsc == -EIO) | |
1696 | return -EIO; | |
1697 | ||
1698 | if (last_tsc_overflow(config, buf, ctx->tsc)) | |
1699 | ctx->rflags |= RING_BUFFER_RFLAG_FULL_TSC; | |
1700 | ||
b5a3dfa5 | 1701 | if (caa_unlikely(subbuf_offset(offsets->begin, ctx->chan) == 0)) { |
852c2936 MD |
1702 | offsets->switch_new_start = 1; /* For offsets->begin */ |
1703 | } else { | |
1704 | offsets->size = config->cb.record_header_size(config, chan, | |
1705 | offsets->begin, | |
1706 | &offsets->pre_header_padding, | |
1707 | ctx); | |
1708 | offsets->size += | |
1709 | lib_ring_buffer_align(offsets->begin + offsets->size, | |
1710 | ctx->largest_align) | |
1711 | + ctx->data_size; | |
b5a3dfa5 | 1712 | if (caa_unlikely(subbuf_offset(offsets->begin, chan) + |
852c2936 MD |
1713 | offsets->size > chan->backend.subbuf_size)) { |
1714 | offsets->switch_old_end = 1; /* For offsets->old */ | |
1715 | offsets->switch_new_start = 1; /* For offsets->begin */ | |
1716 | } | |
1717 | } | |
b5a3dfa5 | 1718 | if (caa_unlikely(offsets->switch_new_start)) { |
e185cf4b | 1719 | unsigned long sb_index, commit_count; |
852c2936 MD |
1720 | |
1721 | /* | |
1722 | * We are typically not filling the previous buffer completely. | |
1723 | */ | |
b5a3dfa5 | 1724 | if (caa_likely(offsets->switch_old_end)) |
852c2936 MD |
1725 | offsets->begin = subbuf_align(offsets->begin, chan); |
1726 | offsets->begin = offsets->begin | |
1727 | + config->cb.subbuffer_header_size(); | |
1728 | /* Test new buffer integrity */ | |
1729 | sb_index = subbuf_index(offsets->begin, chan); | |
e185cf4b MD |
1730 | /* |
1731 | * Read buf->offset before buf->commit_cold[sb_index].cc_sb. | |
1732 | * lib_ring_buffer_check_deliver() has the matching | |
1733 | * memory barriers required around commit_cold cc_sb | |
1734 | * updates to ensure reserve and commit counter updates | |
1735 | * are not seen reordered when updated by another CPU. | |
1736 | */ | |
1737 | cmm_smp_rmb(); | |
1738 | commit_count = v_read(config, | |
1739 | &shmp_index(handle, buf->commit_cold, | |
1740 | sb_index)->cc_sb); | |
1741 | /* Read buf->commit_cold[sb_index].cc_sb before buf->offset. */ | |
1742 | cmm_smp_rmb(); | |
1743 | if (caa_unlikely(offset_cmp != v_read(config, &buf->offset))) { | |
1744 | /* | |
1745 | * The reserve counter have been concurrently updated | |
1746 | * while we read the commit counter. This means the | |
1747 | * commit counter we read might not match buf->offset | |
1748 | * due to concurrent update. We therefore need to retry. | |
1749 | */ | |
1750 | goto retry; | |
1751 | } | |
852c2936 MD |
1752 | reserve_commit_diff = |
1753 | (buf_trunc(offsets->begin, chan) | |
1754 | >> chan->backend.num_subbuf_order) | |
e185cf4b | 1755 | - (commit_count & chan->commit_count_mask); |
b5a3dfa5 | 1756 | if (caa_likely(reserve_commit_diff == 0)) { |
852c2936 | 1757 | /* Next subbuffer not being written to. */ |
b5a3dfa5 | 1758 | if (caa_unlikely(config->mode != RING_BUFFER_OVERWRITE && |
852c2936 MD |
1759 | subbuf_trunc(offsets->begin, chan) |
1760 | - subbuf_trunc((unsigned long) | |
a6352fd4 | 1761 | uatomic_read(&buf->consumed), chan) |
852c2936 | 1762 | >= chan->backend.buf_size)) { |
64493e4f MD |
1763 | unsigned long nr_lost; |
1764 | ||
852c2936 MD |
1765 | /* |
1766 | * We do not overwrite non consumed buffers | |
1767 | * and we are full : record is lost. | |
1768 | */ | |
64493e4f | 1769 | nr_lost = v_read(config, &buf->records_lost_full); |
852c2936 | 1770 | v_inc(config, &buf->records_lost_full); |
64493e4f MD |
1771 | if ((nr_lost & (DBG_PRINT_NR_LOST - 1)) == 0) { |
1772 | DBG("%lu or more records lost in (%s:%d) (buffer full)\n", | |
1773 | nr_lost + 1, chan->backend.name, | |
1774 | buf->backend.cpu); | |
1775 | } | |
852c2936 MD |
1776 | return -ENOBUFS; |
1777 | } else { | |
1778 | /* | |
1779 | * Next subbuffer not being written to, and we | |
1780 | * are either in overwrite mode or the buffer is | |
1781 | * not full. It's safe to write in this new | |
1782 | * subbuffer. | |
1783 | */ | |
1784 | } | |
1785 | } else { | |
64493e4f MD |
1786 | unsigned long nr_lost; |
1787 | ||
852c2936 MD |
1788 | /* |
1789 | * Next subbuffer reserve offset does not match the | |
e185cf4b MD |
1790 | * commit offset, and this did not involve update to the |
1791 | * reserve counter. Drop record in producer-consumer and | |
852c2936 MD |
1792 | * overwrite mode. Caused by either a writer OOPS or too |
1793 | * many nested writes over a reserve/commit pair. | |
1794 | */ | |
64493e4f | 1795 | nr_lost = v_read(config, &buf->records_lost_wrap); |
852c2936 | 1796 | v_inc(config, &buf->records_lost_wrap); |
64493e4f MD |
1797 | if ((nr_lost & (DBG_PRINT_NR_LOST - 1)) == 0) { |
1798 | DBG("%lu or more records lost in (%s:%d) (wrap-around)\n", | |
1799 | nr_lost + 1, chan->backend.name, | |
1800 | buf->backend.cpu); | |
1801 | } | |
852c2936 MD |
1802 | return -EIO; |
1803 | } | |
1804 | offsets->size = | |
1805 | config->cb.record_header_size(config, chan, | |
1806 | offsets->begin, | |
1807 | &offsets->pre_header_padding, | |
1808 | ctx); | |
1809 | offsets->size += | |
1810 | lib_ring_buffer_align(offsets->begin + offsets->size, | |
1811 | ctx->largest_align) | |
1812 | + ctx->data_size; | |
b5a3dfa5 | 1813 | if (caa_unlikely(subbuf_offset(offsets->begin, chan) |
852c2936 | 1814 | + offsets->size > chan->backend.subbuf_size)) { |
64493e4f MD |
1815 | unsigned long nr_lost; |
1816 | ||
852c2936 MD |
1817 | /* |
1818 | * Record too big for subbuffers, report error, don't | |
1819 | * complete the sub-buffer switch. | |
1820 | */ | |
64493e4f | 1821 | nr_lost = v_read(config, &buf->records_lost_big); |
852c2936 | 1822 | v_inc(config, &buf->records_lost_big); |
64493e4f MD |
1823 | if ((nr_lost & (DBG_PRINT_NR_LOST - 1)) == 0) { |
1824 | DBG("%lu or more records lost in (%s:%d) record size " | |
1825 | " of %zu bytes is too large for buffer\n", | |
1826 | nr_lost + 1, chan->backend.name, | |
1827 | buf->backend.cpu, offsets->size); | |
1828 | } | |
852c2936 MD |
1829 | return -ENOSPC; |
1830 | } else { | |
1831 | /* | |
1832 | * We just made a successful buffer switch and the | |
1833 | * record fits in the new subbuffer. Let's write. | |
1834 | */ | |
1835 | } | |
1836 | } else { | |
1837 | /* | |
1838 | * Record fits in the current buffer and we are not on a switch | |
1839 | * boundary. It's safe to write. | |
1840 | */ | |
1841 | } | |
1842 | offsets->end = offsets->begin + offsets->size; | |
1ad21f70 MD |
1843 | |
1844 | if (caa_unlikely(subbuf_offset(offsets->end, chan) == 0)) { | |
1845 | /* | |
1846 | * The offset_end will fall at the very beginning of the next | |
1847 | * subbuffer. | |
1848 | */ | |
1849 | offsets->switch_new_end = 1; /* For offsets->begin */ | |
1850 | } | |
852c2936 MD |
1851 | return 0; |
1852 | } | |
1853 | ||
1854 | /** | |
1855 | * lib_ring_buffer_reserve_slow - Atomic slot reservation in a buffer. | |
1856 | * @ctx: ring buffer context. | |
1857 | * | |
1858 | * Return : -NOBUFS if not enough space, -ENOSPC if event size too large, | |
1859 | * -EIO for other errors, else returns 0. | |
1860 | * It will take care of sub-buffer switching. | |
1861 | */ | |
4cfec15c | 1862 | int lib_ring_buffer_reserve_slow(struct lttng_ust_lib_ring_buffer_ctx *ctx) |
852c2936 MD |
1863 | { |
1864 | struct channel *chan = ctx->chan; | |
38fae1d3 | 1865 | struct lttng_ust_shm_handle *handle = ctx->handle; |
4cfec15c MD |
1866 | const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config; |
1867 | struct lttng_ust_lib_ring_buffer *buf; | |
852c2936 MD |
1868 | struct switch_offsets offsets; |
1869 | int ret; | |
1870 | ||
1871 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) | |
1d498196 | 1872 | buf = shmp(handle, chan->backend.buf[ctx->cpu].shmp); |
852c2936 | 1873 | else |
1d498196 | 1874 | buf = shmp(handle, chan->backend.buf[0].shmp); |
852c2936 MD |
1875 | ctx->buf = buf; |
1876 | ||
1877 | offsets.size = 0; | |
1878 | ||
1879 | do { | |
1880 | ret = lib_ring_buffer_try_reserve_slow(buf, chan, &offsets, | |
1881 | ctx); | |
b5a3dfa5 | 1882 | if (caa_unlikely(ret)) |
852c2936 | 1883 | return ret; |
b5a3dfa5 | 1884 | } while (caa_unlikely(v_cmpxchg(config, &buf->offset, offsets.old, |
852c2936 MD |
1885 | offsets.end) |
1886 | != offsets.old)); | |
1887 | ||
1888 | /* | |
1889 | * Atomically update last_tsc. This update races against concurrent | |
1890 | * atomic updates, but the race will always cause supplementary full TSC | |
1891 | * records, never the opposite (missing a full TSC record when it would | |
1892 | * be needed). | |
1893 | */ | |
1894 | save_last_tsc(config, buf, ctx->tsc); | |
1895 | ||
1896 | /* | |
1897 | * Push the reader if necessary | |
1898 | */ | |
1899 | lib_ring_buffer_reserve_push_reader(buf, chan, offsets.end - 1); | |
1900 | ||
1901 | /* | |
1902 | * Clear noref flag for this subbuffer. | |
1903 | */ | |
1904 | lib_ring_buffer_clear_noref(config, &buf->backend, | |
1d498196 MD |
1905 | subbuf_index(offsets.end - 1, chan), |
1906 | handle); | |
852c2936 MD |
1907 | |
1908 | /* | |
1909 | * Switch old subbuffer if needed. | |
1910 | */ | |
b5a3dfa5 | 1911 | if (caa_unlikely(offsets.switch_old_end)) { |
852c2936 | 1912 | lib_ring_buffer_clear_noref(config, &buf->backend, |
1d498196 MD |
1913 | subbuf_index(offsets.old - 1, chan), |
1914 | handle); | |
1915 | lib_ring_buffer_switch_old_end(buf, chan, &offsets, ctx->tsc, handle); | |
852c2936 MD |
1916 | } |
1917 | ||
1918 | /* | |
1919 | * Populate new subbuffer. | |
1920 | */ | |
b5a3dfa5 | 1921 | if (caa_unlikely(offsets.switch_new_start)) |
1d498196 | 1922 | lib_ring_buffer_switch_new_start(buf, chan, &offsets, ctx->tsc, handle); |
852c2936 | 1923 | |
1ad21f70 MD |
1924 | if (caa_unlikely(offsets.switch_new_end)) |
1925 | lib_ring_buffer_switch_new_end(buf, chan, &offsets, ctx->tsc, handle); | |
1926 | ||
852c2936 MD |
1927 | ctx->slot_size = offsets.size; |
1928 | ctx->pre_offset = offsets.begin; | |
1929 | ctx->buf_offset = offsets.begin + offsets.pre_header_padding; | |
1930 | return 0; | |
1931 | } | |
f645cfa7 MD |
1932 | |
1933 | /* | |
1934 | * Force a read (imply TLS fixup for dlopen) of TLS variables. | |
1935 | */ | |
1936 | void lttng_fixup_ringbuffer_tls(void) | |
1937 | { | |
8c90a710 | 1938 | asm volatile ("" : : "m" (URCU_TLS(lib_ring_buffer_nesting))); |
f645cfa7 | 1939 | } |
03d2d293 MD |
1940 | |
1941 | void lib_ringbuffer_signal_init(void) | |
1942 | { | |
1943 | sigset_t mask; | |
1944 | int ret; | |
1945 | ||
1946 | /* | |
1947 | * Block signal for entire process, so only our thread processes | |
1948 | * it. | |
1949 | */ | |
1950 | rb_setmask(&mask); | |
1951 | ret = pthread_sigmask(SIG_BLOCK, &mask, NULL); | |
1952 | if (ret) { | |
1953 | errno = ret; | |
1954 | PERROR("pthread_sigmask"); | |
1955 | } | |
1956 | } |