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d086f507 JD |
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 | } | |
d88744a4 JD |
54 | ret = sigaddset(mask, LTTNG_SESSIOND_SIG_ROTATE_PENDING); |
55 | if (ret) { | |
56 | PERROR("sigaddset switch"); | |
57 | } | |
259c2674 JD |
58 | ret = sigaddset(mask, LTTNG_SESSIOND_SIG_ROTATE_TIMER); |
59 | if (ret) { | |
60 | PERROR("sigaddset switch"); | |
61 | } | |
d086f507 JD |
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 | ||
d88744a4 JD |
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 | */ | |
259c2674 | 219 | int sessiond_timer_rotate_pending_stop(struct ltt_session *session) |
d88744a4 JD |
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"); | |
259c2674 JD |
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; | |
d88744a4 JD |
273 | } |
274 | ||
259c2674 JD |
275 | session->rotate_timer_enabled = false; |
276 | ret = 0; | |
277 | end: | |
278 | return ret; | |
d88744a4 JD |
279 | } |
280 | ||
d086f507 JD |
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 | ||
d88744a4 JD |
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; | |
d88744a4 | 337 | char *c = "!"; |
f5eeb9d7 | 338 | struct sessiond_rotation_timer *timer_data = NULL; |
d88744a4 JD |
339 | |
340 | pthread_mutex_lock(&ctx->rotation_timer_queue->lock); | |
f5eeb9d7 | 341 | if (check_duplicate_timer_job(ctx, session, signal)) { |
d88744a4 JD |
342 | /* |
343 | * This timer job is already pending, we don't need to add | |
344 | * it. | |
345 | */ | |
d88744a4 JD |
346 | ret = 0; |
347 | goto end; | |
348 | } | |
f5eeb9d7 JG |
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); | |
d88744a4 JD |
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"); | |
f5eeb9d7 | 375 | goto end; |
d88744a4 JD |
376 | } |
377 | ||
378 | ret = 0; | |
d88744a4 | 379 | |
d88744a4 | 380 | end: |
f5eeb9d7 | 381 | pthread_mutex_unlock(&ctx->rotation_timer_queue->lock); |
d88744a4 JD |
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) | |
259c2674 JD |
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) | |
d88744a4 JD |
408 | { |
409 | int ret; | |
259c2674 JD |
410 | /* |
411 | * The session cannot be freed/destroyed while we are running this | |
412 | * signal handler. | |
413 | */ | |
d88744a4 JD |
414 | struct ltt_session *session = si->si_value.sival_ptr; |
415 | assert(session); | |
416 | ||
259c2674 | 417 | ret = enqueue_timer_rotate_job(ctx, session, LTTNG_SESSIOND_SIG_ROTATE_TIMER); |
d88744a4 JD |
418 | if (ret) { |
419 | PERROR("wakeup rotate pipe"); | |
420 | } | |
421 | } | |
422 | ||
d086f507 JD |
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; | |
d88744a4 JD |
468 | } else if (signr == LTTNG_SESSIOND_SIG_ROTATE_PENDING) { |
469 | relay_rotation_pending_timer(ctx, info.si_signo, &info); | |
259c2674 JD |
470 | } else if (signr == LTTNG_SESSIOND_SIG_ROTATE_TIMER) { |
471 | rotate_timer(ctx, info.si_signo, &info); | |
d086f507 JD |
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 | } |