| 1 | /* |
| 2 | * Copyright (C) 2017 - Julien Desfossez <jdesfossez@efficios.com> |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify it |
| 5 | * under the terms of the GNU General Public License, version 2 only, as |
| 6 | * published by the Free Software Foundation. |
| 7 | * |
| 8 | * This program is distributed in the hope that it will be useful, but WITHOUT |
| 9 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 10 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
| 11 | * more details. |
| 12 | * |
| 13 | * You should have received a copy of the GNU General Public License along with |
| 14 | * this program; if not, write to the Free Software Foundation, Inc., 51 |
| 15 | * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| 16 | */ |
| 17 | |
| 18 | #define _LGPL_SOURCE |
| 19 | #include <assert.h> |
| 20 | #include <inttypes.h> |
| 21 | #include <signal.h> |
| 22 | |
| 23 | #include "sessiond-timer.h" |
| 24 | #include "health-sessiond.h" |
| 25 | #include "rotation-thread.h" |
| 26 | |
| 27 | static |
| 28 | struct timer_signal_data timer_signal = { |
| 29 | .tid = 0, |
| 30 | .qs_done = 0, |
| 31 | .lock = PTHREAD_MUTEX_INITIALIZER, |
| 32 | }; |
| 33 | |
| 34 | /* |
| 35 | * Set custom signal mask to current thread. |
| 36 | */ |
| 37 | static |
| 38 | void setmask(sigset_t *mask) |
| 39 | { |
| 40 | int ret; |
| 41 | |
| 42 | ret = sigemptyset(mask); |
| 43 | if (ret) { |
| 44 | PERROR("sigemptyset"); |
| 45 | } |
| 46 | ret = sigaddset(mask, LTTNG_SESSIOND_SIG_TEARDOWN); |
| 47 | if (ret) { |
| 48 | PERROR("sigaddset teardown"); |
| 49 | } |
| 50 | ret = sigaddset(mask, LTTNG_SESSIOND_SIG_EXIT); |
| 51 | if (ret) { |
| 52 | PERROR("sigaddset exit"); |
| 53 | } |
| 54 | ret = sigaddset(mask, LTTNG_SESSIOND_SIG_ROTATE_PENDING); |
| 55 | if (ret) { |
| 56 | PERROR("sigaddset switch"); |
| 57 | } |
| 58 | ret = sigaddset(mask, LTTNG_SESSIOND_SIG_ROTATE_TIMER); |
| 59 | if (ret) { |
| 60 | PERROR("sigaddset switch"); |
| 61 | } |
| 62 | } |
| 63 | |
| 64 | /* |
| 65 | * This is the same function as consumer_timer_signal_thread_qs, when it |
| 66 | * returns, it means that no timer signr is currently pending or being handled |
| 67 | * by the timer thread. This cannot be called from the timer thread. |
| 68 | */ |
| 69 | static |
| 70 | void sessiond_timer_signal_thread_qs(unsigned int signr) |
| 71 | { |
| 72 | sigset_t pending_set; |
| 73 | int ret; |
| 74 | |
| 75 | /* |
| 76 | * We need to be the only thread interacting with the thread |
| 77 | * that manages signals for teardown synchronization. |
| 78 | */ |
| 79 | pthread_mutex_lock(&timer_signal.lock); |
| 80 | |
| 81 | /* Ensure we don't have any signal queued for this session. */ |
| 82 | for (;;) { |
| 83 | ret = sigemptyset(&pending_set); |
| 84 | if (ret == -1) { |
| 85 | PERROR("sigemptyset"); |
| 86 | } |
| 87 | ret = sigpending(&pending_set); |
| 88 | if (ret == -1) { |
| 89 | PERROR("sigpending"); |
| 90 | } |
| 91 | if (!sigismember(&pending_set, signr)) { |
| 92 | break; |
| 93 | } |
| 94 | caa_cpu_relax(); |
| 95 | } |
| 96 | |
| 97 | /* |
| 98 | * From this point, no new signal handler will be fired that would try to |
| 99 | * access "session". However, we still need to wait for any currently |
| 100 | * executing handler to complete. |
| 101 | */ |
| 102 | cmm_smp_mb(); |
| 103 | CMM_STORE_SHARED(timer_signal.qs_done, 0); |
| 104 | cmm_smp_mb(); |
| 105 | |
| 106 | /* |
| 107 | * Kill with LTTNG_SESSIOND_SIG_TEARDOWN, so signal management thread |
| 108 | * wakes up. |
| 109 | */ |
| 110 | kill(getpid(), LTTNG_SESSIOND_SIG_TEARDOWN); |
| 111 | |
| 112 | while (!CMM_LOAD_SHARED(timer_signal.qs_done)) { |
| 113 | caa_cpu_relax(); |
| 114 | } |
| 115 | cmm_smp_mb(); |
| 116 | |
| 117 | pthread_mutex_unlock(&timer_signal.lock); |
| 118 | } |
| 119 | |
| 120 | /* |
| 121 | * Start a timer on a session that will fire at a given interval |
| 122 | * (timer_interval_us) and fire a given signal (signal). |
| 123 | * |
| 124 | * Returns a negative value on error, 0 if a timer was created, and |
| 125 | * a positive value if no timer was created (not an error). |
| 126 | */ |
| 127 | static |
| 128 | int session_timer_start(timer_t *timer_id, struct ltt_session *session, |
| 129 | unsigned int timer_interval_us, int signal, bool one_shot) |
| 130 | { |
| 131 | int ret = 0, delete_ret; |
| 132 | struct sigevent sev; |
| 133 | struct itimerspec its; |
| 134 | |
| 135 | assert(session); |
| 136 | |
| 137 | sev.sigev_notify = SIGEV_SIGNAL; |
| 138 | sev.sigev_signo = signal; |
| 139 | sev.sigev_value.sival_ptr = session; |
| 140 | ret = timer_create(CLOCKID, &sev, timer_id); |
| 141 | if (ret == -1) { |
| 142 | PERROR("timer_create"); |
| 143 | goto end; |
| 144 | } |
| 145 | |
| 146 | its.it_value.tv_sec = timer_interval_us / 1000000; |
| 147 | its.it_value.tv_nsec = (timer_interval_us % 1000000) * 1000; |
| 148 | if (one_shot) { |
| 149 | its.it_interval.tv_sec = 0; |
| 150 | its.it_interval.tv_nsec = 0; |
| 151 | } else { |
| 152 | its.it_interval.tv_sec = its.it_value.tv_sec; |
| 153 | its.it_interval.tv_nsec = its.it_value.tv_nsec; |
| 154 | } |
| 155 | |
| 156 | ret = timer_settime(*timer_id, 0, &its, NULL); |
| 157 | if (ret == -1) { |
| 158 | PERROR("timer_settime"); |
| 159 | goto error_destroy_timer; |
| 160 | } |
| 161 | goto end; |
| 162 | |
| 163 | error_destroy_timer: |
| 164 | delete_ret = timer_delete(*timer_id); |
| 165 | if (delete_ret == -1) { |
| 166 | PERROR("timer_delete"); |
| 167 | } |
| 168 | |
| 169 | end: |
| 170 | return ret; |
| 171 | } |
| 172 | |
| 173 | static |
| 174 | int session_timer_stop(timer_t *timer_id, int signal) |
| 175 | { |
| 176 | int ret = 0; |
| 177 | |
| 178 | ret = timer_delete(*timer_id); |
| 179 | if (ret == -1) { |
| 180 | PERROR("timer_delete"); |
| 181 | goto end; |
| 182 | } |
| 183 | |
| 184 | sessiond_timer_signal_thread_qs(signal); |
| 185 | *timer_id = 0; |
| 186 | end: |
| 187 | return ret; |
| 188 | } |
| 189 | |
| 190 | int sessiond_timer_rotate_pending_start(struct ltt_session *session, |
| 191 | unsigned int interval_us) |
| 192 | { |
| 193 | int ret; |
| 194 | |
| 195 | DBG("Enabling rotate pending timer on session %" PRIu64, session->id); |
| 196 | /* |
| 197 | * We arm this timer in a one-shot mode so we don't have to disable it |
| 198 | * explicitly (which could deadlock if the timer thread is blocked writing |
| 199 | * in the rotation_timer_pipe). |
| 200 | * Instead, we re-arm it if needed after the rotation_pending check as |
| 201 | * returned. Also, this timer is usually only needed once, so there is no |
| 202 | * need to go through the whole signal teardown scheme everytime. |
| 203 | */ |
| 204 | ret = session_timer_start(&session->rotate_relay_pending_timer, |
| 205 | session, interval_us, |
| 206 | LTTNG_SESSIOND_SIG_ROTATE_PENDING, |
| 207 | /* one-shot */ true); |
| 208 | if (ret == 0) { |
| 209 | session->rotate_relay_pending_timer_enabled = true; |
| 210 | } |
| 211 | |
| 212 | return ret; |
| 213 | } |
| 214 | |
| 215 | /* |
| 216 | * Stop and delete the channel's live timer. |
| 217 | * Called with session and session_list locks held. |
| 218 | */ |
| 219 | int sessiond_timer_rotate_pending_stop(struct ltt_session *session) |
| 220 | { |
| 221 | int ret; |
| 222 | |
| 223 | assert(session); |
| 224 | |
| 225 | DBG("Disabling timer rotate pending on session %" PRIu64, session->id); |
| 226 | ret = session_timer_stop(&session->rotate_relay_pending_timer, |
| 227 | LTTNG_SESSIOND_SIG_ROTATE_PENDING); |
| 228 | if (ret == -1) { |
| 229 | ERR("Failed to stop rotate_pending timer"); |
| 230 | } else { |
| 231 | session->rotate_relay_pending_timer_enabled = false; |
| 232 | } |
| 233 | return ret; |
| 234 | } |
| 235 | |
| 236 | int sessiond_rotate_timer_start(struct ltt_session *session, |
| 237 | unsigned int interval_us) |
| 238 | { |
| 239 | int ret; |
| 240 | |
| 241 | DBG("Enabling rotation timer on session \"%s\" (%ui µs)", session->name, |
| 242 | interval_us); |
| 243 | ret = session_timer_start(&session->rotate_timer, session, interval_us, |
| 244 | LTTNG_SESSIOND_SIG_ROTATE_TIMER, false); |
| 245 | if (ret < 0) { |
| 246 | goto end; |
| 247 | } |
| 248 | session->rotate_timer_enabled = true; |
| 249 | end: |
| 250 | return ret; |
| 251 | } |
| 252 | |
| 253 | /* |
| 254 | * Stop and delete the channel's live timer. |
| 255 | */ |
| 256 | int sessiond_rotate_timer_stop(struct ltt_session *session) |
| 257 | { |
| 258 | int ret = 0; |
| 259 | |
| 260 | assert(session); |
| 261 | |
| 262 | if (!session->rotate_timer_enabled) { |
| 263 | goto end; |
| 264 | } |
| 265 | |
| 266 | DBG("Disabling rotation timer on session %s", session->name); |
| 267 | ret = session_timer_stop(&session->rotate_timer, |
| 268 | LTTNG_SESSIOND_SIG_ROTATE_TIMER); |
| 269 | if (ret < 0) { |
| 270 | ERR("Failed to stop rotate timer of session \"%s\"", |
| 271 | session->name); |
| 272 | goto end; |
| 273 | } |
| 274 | |
| 275 | session->rotate_timer_enabled = false; |
| 276 | ret = 0; |
| 277 | end: |
| 278 | return ret; |
| 279 | } |
| 280 | |
| 281 | /* |
| 282 | * Block the RT signals for the entire process. It must be called from the |
| 283 | * sessiond main before creating the threads |
| 284 | */ |
| 285 | int sessiond_timer_signal_init(void) |
| 286 | { |
| 287 | int ret; |
| 288 | sigset_t mask; |
| 289 | |
| 290 | /* Block signal for entire process, so only our thread processes it. */ |
| 291 | setmask(&mask); |
| 292 | ret = pthread_sigmask(SIG_BLOCK, &mask, NULL); |
| 293 | if (ret) { |
| 294 | errno = ret; |
| 295 | PERROR("pthread_sigmask"); |
| 296 | return -1; |
| 297 | } |
| 298 | return 0; |
| 299 | } |
| 300 | |
| 301 | /* |
| 302 | * Called with the rotation_timer_queue lock held. |
| 303 | * Return true if the same timer job already exists in the queue, false if not. |
| 304 | */ |
| 305 | static |
| 306 | bool check_duplicate_timer_job(struct timer_thread_parameters *ctx, |
| 307 | struct ltt_session *session, unsigned int signal) |
| 308 | { |
| 309 | bool ret = false; |
| 310 | struct sessiond_rotation_timer *node; |
| 311 | |
| 312 | rcu_read_lock(); |
| 313 | cds_list_for_each_entry(node, &ctx->rotation_timer_queue->list, head) { |
| 314 | if (node->session_id == session->id && node->signal == signal) { |
| 315 | ret = true; |
| 316 | goto end; |
| 317 | } |
| 318 | } |
| 319 | |
| 320 | end: |
| 321 | rcu_read_unlock(); |
| 322 | return ret; |
| 323 | } |
| 324 | |
| 325 | /* |
| 326 | * Add the session ID and signal value to the rotation_timer_queue if it is |
| 327 | * not already there and wakeup the rotation thread. The rotation thread |
| 328 | * empties the whole queue everytime it is woken up. The event_pipe is |
| 329 | * non-blocking, if it would block, we just return because we know the |
| 330 | * rotation thread will be awaken anyway. |
| 331 | */ |
| 332 | static |
| 333 | int enqueue_timer_rotate_job(struct timer_thread_parameters *ctx, |
| 334 | struct ltt_session *session, unsigned int signal) |
| 335 | { |
| 336 | int ret; |
| 337 | char *c = "!"; |
| 338 | struct sessiond_rotation_timer *timer_data = NULL; |
| 339 | |
| 340 | pthread_mutex_lock(&ctx->rotation_timer_queue->lock); |
| 341 | if (check_duplicate_timer_job(ctx, session, signal)) { |
| 342 | /* |
| 343 | * This timer job is already pending, we don't need to add |
| 344 | * it. |
| 345 | */ |
| 346 | ret = 0; |
| 347 | goto end; |
| 348 | } |
| 349 | |
| 350 | timer_data = zmalloc(sizeof(struct sessiond_rotation_timer)); |
| 351 | if (!timer_data) { |
| 352 | PERROR("Allocation of timer data"); |
| 353 | ret = -1; |
| 354 | goto end; |
| 355 | } |
| 356 | timer_data->session_id = session->id; |
| 357 | timer_data->signal = signal; |
| 358 | cds_list_add_tail(&timer_data->head, |
| 359 | &ctx->rotation_timer_queue->list); |
| 360 | |
| 361 | ret = lttng_write( |
| 362 | lttng_pipe_get_writefd(ctx->rotation_timer_queue->event_pipe), |
| 363 | c, 1); |
| 364 | if (ret < 0) { |
| 365 | /* |
| 366 | * We do not want to block in the timer handler, the job has been |
| 367 | * enqueued in the list, the wakeup pipe is probably full, the job |
| 368 | * will be processed when the rotation_thread catches up. |
| 369 | */ |
| 370 | if (errno == EAGAIN || errno == EWOULDBLOCK) { |
| 371 | ret = 0; |
| 372 | goto end; |
| 373 | } |
| 374 | PERROR("Timer wakeup rotation thread"); |
| 375 | goto end; |
| 376 | } |
| 377 | |
| 378 | ret = 0; |
| 379 | |
| 380 | end: |
| 381 | pthread_mutex_unlock(&ctx->rotation_timer_queue->lock); |
| 382 | return ret; |
| 383 | } |
| 384 | |
| 385 | /* |
| 386 | * Ask the rotation thread to check if the last rotation started in this |
| 387 | * session is still pending on the relay. |
| 388 | */ |
| 389 | static |
| 390 | void relay_rotation_pending_timer(struct timer_thread_parameters *ctx, |
| 391 | int sig, siginfo_t *si) |
| 392 | { |
| 393 | struct ltt_session *session = si->si_value.sival_ptr; |
| 394 | |
| 395 | assert(session); |
| 396 | |
| 397 | (void) enqueue_timer_rotate_job(ctx, session, |
| 398 | LTTNG_SESSIOND_SIG_ROTATE_PENDING); |
| 399 | } |
| 400 | |
| 401 | /* |
| 402 | * Handle the LTTNG_SESSIOND_SIG_ROTATE_TIMER timer. Add the session ID to |
| 403 | * the rotation_timer_queue so the rotation thread can trigger a new rotation |
| 404 | * on that session. |
| 405 | */ |
| 406 | static |
| 407 | void rotate_timer(struct timer_thread_parameters *ctx, int sig, siginfo_t *si) |
| 408 | { |
| 409 | int ret; |
| 410 | /* |
| 411 | * The session cannot be freed/destroyed while we are running this |
| 412 | * signal handler. |
| 413 | */ |
| 414 | struct ltt_session *session = si->si_value.sival_ptr; |
| 415 | assert(session); |
| 416 | |
| 417 | ret = enqueue_timer_rotate_job(ctx, session, LTTNG_SESSIOND_SIG_ROTATE_TIMER); |
| 418 | if (ret) { |
| 419 | PERROR("wakeup rotate pipe"); |
| 420 | } |
| 421 | } |
| 422 | |
| 423 | /* |
| 424 | * This thread is the sighandler for the timer signals. |
| 425 | */ |
| 426 | void *sessiond_timer_thread(void *data) |
| 427 | { |
| 428 | int signr; |
| 429 | sigset_t mask; |
| 430 | siginfo_t info; |
| 431 | struct timer_thread_parameters *ctx = data; |
| 432 | |
| 433 | rcu_register_thread(); |
| 434 | rcu_thread_online(); |
| 435 | |
| 436 | health_register(health_sessiond, HEALTH_SESSIOND_TYPE_TIMER); |
| 437 | |
| 438 | health_code_update(); |
| 439 | |
| 440 | /* Only self thread will receive signal mask. */ |
| 441 | setmask(&mask); |
| 442 | CMM_STORE_SHARED(timer_signal.tid, pthread_self()); |
| 443 | |
| 444 | while (1) { |
| 445 | health_code_update(); |
| 446 | |
| 447 | health_poll_entry(); |
| 448 | signr = sigwaitinfo(&mask, &info); |
| 449 | health_poll_exit(); |
| 450 | |
| 451 | /* |
| 452 | * NOTE: cascading conditions are used instead of a switch case |
| 453 | * since the use of SIGRTMIN in the definition of the signals' |
| 454 | * values prevents the reduction to an integer constant. |
| 455 | */ |
| 456 | if (signr == -1) { |
| 457 | if (errno != EINTR) { |
| 458 | PERROR("sigwaitinfo"); |
| 459 | } |
| 460 | continue; |
| 461 | } else if (signr == LTTNG_SESSIOND_SIG_TEARDOWN) { |
| 462 | cmm_smp_mb(); |
| 463 | CMM_STORE_SHARED(timer_signal.qs_done, 1); |
| 464 | cmm_smp_mb(); |
| 465 | DBG("Signal timer metadata thread teardown"); |
| 466 | } else if (signr == LTTNG_SESSIOND_SIG_EXIT) { |
| 467 | goto end; |
| 468 | } else if (signr == LTTNG_SESSIOND_SIG_ROTATE_PENDING) { |
| 469 | relay_rotation_pending_timer(ctx, info.si_signo, &info); |
| 470 | } else if (signr == LTTNG_SESSIOND_SIG_ROTATE_TIMER) { |
| 471 | rotate_timer(ctx, info.si_signo, &info); |
| 472 | } else { |
| 473 | ERR("Unexpected signal %d\n", info.si_signo); |
| 474 | } |
| 475 | } |
| 476 | |
| 477 | end: |
| 478 | DBG("[timer-thread] Exit"); |
| 479 | health_unregister(health_sessiond); |
| 480 | rcu_thread_offline(); |
| 481 | rcu_unregister_thread(); |
| 482 | return NULL; |
| 483 | } |