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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 | } | |
d086f507 JD |
58 | } |
59 | ||
60 | /* | |
61 | * This is the same function as consumer_timer_signal_thread_qs, when it | |
62 | * returns, it means that no timer signr is currently pending or being handled | |
63 | * by the timer thread. This cannot be called from the timer thread. | |
64 | */ | |
65 | static | |
66 | void sessiond_timer_signal_thread_qs(unsigned int signr) | |
67 | { | |
68 | sigset_t pending_set; | |
69 | int ret; | |
70 | ||
71 | /* | |
72 | * We need to be the only thread interacting with the thread | |
73 | * that manages signals for teardown synchronization. | |
74 | */ | |
75 | pthread_mutex_lock(&timer_signal.lock); | |
76 | ||
77 | /* Ensure we don't have any signal queued for this session. */ | |
78 | for (;;) { | |
79 | ret = sigemptyset(&pending_set); | |
80 | if (ret == -1) { | |
81 | PERROR("sigemptyset"); | |
82 | } | |
83 | ret = sigpending(&pending_set); | |
84 | if (ret == -1) { | |
85 | PERROR("sigpending"); | |
86 | } | |
87 | if (!sigismember(&pending_set, signr)) { | |
88 | break; | |
89 | } | |
90 | caa_cpu_relax(); | |
91 | } | |
92 | ||
93 | /* | |
94 | * From this point, no new signal handler will be fired that would try to | |
95 | * access "session". However, we still need to wait for any currently | |
96 | * executing handler to complete. | |
97 | */ | |
98 | cmm_smp_mb(); | |
99 | CMM_STORE_SHARED(timer_signal.qs_done, 0); | |
100 | cmm_smp_mb(); | |
101 | ||
102 | /* | |
103 | * Kill with LTTNG_SESSIOND_SIG_TEARDOWN, so signal management thread | |
104 | * wakes up. | |
105 | */ | |
106 | kill(getpid(), LTTNG_SESSIOND_SIG_TEARDOWN); | |
107 | ||
108 | while (!CMM_LOAD_SHARED(timer_signal.qs_done)) { | |
109 | caa_cpu_relax(); | |
110 | } | |
111 | cmm_smp_mb(); | |
112 | ||
113 | pthread_mutex_unlock(&timer_signal.lock); | |
114 | } | |
115 | ||
116 | /* | |
117 | * Start a timer on a session that will fire at a given interval | |
118 | * (timer_interval_us) and fire a given signal (signal). | |
119 | * | |
120 | * Returns a negative value on error, 0 if a timer was created, and | |
121 | * a positive value if no timer was created (not an error). | |
122 | */ | |
123 | static | |
124 | int session_timer_start(timer_t *timer_id, struct ltt_session *session, | |
125 | unsigned int timer_interval_us, int signal, bool one_shot) | |
126 | { | |
127 | int ret = 0, delete_ret; | |
128 | struct sigevent sev; | |
129 | struct itimerspec its; | |
130 | ||
131 | assert(session); | |
132 | ||
133 | sev.sigev_notify = SIGEV_SIGNAL; | |
134 | sev.sigev_signo = signal; | |
135 | sev.sigev_value.sival_ptr = session; | |
136 | ret = timer_create(CLOCKID, &sev, timer_id); | |
137 | if (ret == -1) { | |
138 | PERROR("timer_create"); | |
139 | goto end; | |
140 | } | |
141 | ||
142 | its.it_value.tv_sec = timer_interval_us / 1000000; | |
143 | its.it_value.tv_nsec = (timer_interval_us % 1000000) * 1000; | |
144 | if (one_shot) { | |
145 | its.it_interval.tv_sec = 0; | |
146 | its.it_interval.tv_nsec = 0; | |
147 | } else { | |
148 | its.it_interval.tv_sec = its.it_value.tv_sec; | |
149 | its.it_interval.tv_nsec = its.it_value.tv_nsec; | |
150 | } | |
151 | ||
152 | ret = timer_settime(*timer_id, 0, &its, NULL); | |
153 | if (ret == -1) { | |
154 | PERROR("timer_settime"); | |
155 | goto error_destroy_timer; | |
156 | } | |
157 | goto end; | |
158 | ||
159 | error_destroy_timer: | |
160 | delete_ret = timer_delete(*timer_id); | |
161 | if (delete_ret == -1) { | |
162 | PERROR("timer_delete"); | |
163 | } | |
164 | ||
165 | end: | |
166 | return ret; | |
167 | } | |
168 | ||
169 | static | |
170 | int session_timer_stop(timer_t *timer_id, int signal) | |
171 | { | |
172 | int ret = 0; | |
173 | ||
174 | ret = timer_delete(*timer_id); | |
175 | if (ret == -1) { | |
176 | PERROR("timer_delete"); | |
177 | goto end; | |
178 | } | |
179 | ||
180 | sessiond_timer_signal_thread_qs(signal); | |
181 | *timer_id = 0; | |
182 | end: | |
183 | return ret; | |
184 | } | |
185 | ||
d88744a4 JD |
186 | int sessiond_timer_rotate_pending_start(struct ltt_session *session, |
187 | unsigned int interval_us) | |
188 | { | |
189 | int ret; | |
190 | ||
191 | DBG("Enabling rotate pending timer on session %" PRIu64, session->id); | |
192 | /* | |
193 | * We arm this timer in a one-shot mode so we don't have to disable it | |
194 | * explicitly (which could deadlock if the timer thread is blocked writing | |
195 | * in the rotation_timer_pipe). | |
196 | * Instead, we re-arm it if needed after the rotation_pending check as | |
197 | * returned. Also, this timer is usually only needed once, so there is no | |
198 | * need to go through the whole signal teardown scheme everytime. | |
199 | */ | |
200 | ret = session_timer_start(&session->rotate_relay_pending_timer, | |
201 | session, interval_us, | |
202 | LTTNG_SESSIOND_SIG_ROTATE_PENDING, | |
203 | /* one-shot */ true); | |
204 | if (ret == 0) { | |
205 | session->rotate_relay_pending_timer_enabled = true; | |
206 | } | |
207 | ||
208 | return ret; | |
209 | } | |
210 | ||
211 | /* | |
212 | * Stop and delete the channel's live timer. | |
213 | * Called with session and session_list locks held. | |
214 | */ | |
215 | void sessiond_timer_rotate_pending_stop(struct ltt_session *session) | |
216 | { | |
217 | int ret; | |
218 | ||
219 | assert(session); | |
220 | ||
221 | DBG("Disabling timer rotate pending on session %" PRIu64, session->id); | |
222 | ret = session_timer_stop(&session->rotate_relay_pending_timer, | |
223 | LTTNG_SESSIOND_SIG_ROTATE_PENDING); | |
224 | if (ret == -1) { | |
225 | ERR("Failed to stop rotate_pending timer"); | |
226 | } | |
227 | ||
228 | session->rotate_relay_pending_timer_enabled = false; | |
229 | } | |
230 | ||
d086f507 JD |
231 | /* |
232 | * Block the RT signals for the entire process. It must be called from the | |
233 | * sessiond main before creating the threads | |
234 | */ | |
235 | int sessiond_timer_signal_init(void) | |
236 | { | |
237 | int ret; | |
238 | sigset_t mask; | |
239 | ||
240 | /* Block signal for entire process, so only our thread processes it. */ | |
241 | setmask(&mask); | |
242 | ret = pthread_sigmask(SIG_BLOCK, &mask, NULL); | |
243 | if (ret) { | |
244 | errno = ret; | |
245 | PERROR("pthread_sigmask"); | |
246 | return -1; | |
247 | } | |
248 | return 0; | |
249 | } | |
250 | ||
d88744a4 JD |
251 | /* |
252 | * Called with the rotation_timer_queue lock held. | |
253 | * Return true if the same timer job already exists in the queue, false if not. | |
254 | */ | |
255 | static | |
256 | bool check_duplicate_timer_job(struct timer_thread_parameters *ctx, | |
257 | struct ltt_session *session, unsigned int signal) | |
258 | { | |
259 | bool ret = false; | |
260 | struct sessiond_rotation_timer *node; | |
261 | ||
262 | rcu_read_lock(); | |
263 | cds_list_for_each_entry(node, &ctx->rotation_timer_queue->list, head) { | |
264 | if (node->session_id == session->id && node->signal == signal) { | |
265 | ret = true; | |
266 | goto end; | |
267 | } | |
268 | } | |
269 | ||
270 | end: | |
271 | rcu_read_unlock(); | |
272 | return ret; | |
273 | } | |
274 | ||
275 | /* | |
276 | * Add the session ID and signal value to the rotation_timer_queue if it is | |
277 | * not already there and wakeup the rotation thread. The rotation thread | |
278 | * empties the whole queue everytime it is woken up. The event_pipe is | |
279 | * non-blocking, if it would block, we just return because we know the | |
280 | * rotation thread will be awaken anyway. | |
281 | */ | |
282 | static | |
283 | int enqueue_timer_rotate_job(struct timer_thread_parameters *ctx, | |
284 | struct ltt_session *session, unsigned int signal) | |
285 | { | |
286 | int ret; | |
287 | bool has_duplicate_timer_job; | |
288 | char *c = "!"; | |
289 | ||
290 | pthread_mutex_lock(&ctx->rotation_timer_queue->lock); | |
291 | has_duplicate_timer_job = check_duplicate_timer_job(ctx, session, | |
292 | signal); | |
293 | ||
294 | if (!has_duplicate_timer_job) { | |
295 | struct sessiond_rotation_timer *timer_data = NULL; | |
296 | ||
297 | timer_data = zmalloc(sizeof(struct sessiond_rotation_timer)); | |
298 | if (!timer_data) { | |
299 | PERROR("Allocation of timer data"); | |
300 | goto error; | |
301 | } | |
302 | timer_data->session_id = session->id; | |
303 | timer_data->signal = signal; | |
304 | cds_list_add_tail(&timer_data->head, | |
305 | &ctx->rotation_timer_queue->list); | |
306 | } else { | |
307 | /* | |
308 | * This timer job is already pending, we don't need to add | |
309 | * it. | |
310 | */ | |
311 | pthread_mutex_unlock(&ctx->rotation_timer_queue->lock); | |
312 | ret = 0; | |
313 | goto end; | |
314 | } | |
315 | pthread_mutex_unlock(&ctx->rotation_timer_queue->lock); | |
316 | ||
317 | ret = lttng_write( | |
318 | lttng_pipe_get_writefd(ctx->rotation_timer_queue->event_pipe), | |
319 | c, 1); | |
320 | if (ret < 0) { | |
321 | /* | |
322 | * We do not want to block in the timer handler, the job has been | |
323 | * enqueued in the list, the wakeup pipe is probably full, the job | |
324 | * will be processed when the rotation_thread catches up. | |
325 | */ | |
326 | if (errno == EAGAIN || errno == EWOULDBLOCK) { | |
327 | ret = 0; | |
328 | goto end; | |
329 | } | |
330 | PERROR("Timer wakeup rotation thread"); | |
331 | goto error; | |
332 | } | |
333 | ||
334 | ret = 0; | |
335 | goto end; | |
336 | ||
337 | error: | |
338 | ret = -1; | |
339 | end: | |
340 | return ret; | |
341 | } | |
342 | ||
343 | /* | |
344 | * Ask the rotation thread to check if the last rotation started in this | |
345 | * session is still pending on the relay. | |
346 | */ | |
347 | static | |
348 | void relay_rotation_pending_timer(struct timer_thread_parameters *ctx, | |
349 | int sig, siginfo_t *si) | |
350 | { | |
351 | int ret; | |
352 | struct ltt_session *session = si->si_value.sival_ptr; | |
353 | assert(session); | |
354 | ||
355 | ret = enqueue_timer_rotate_job(ctx, session, LTTNG_SESSIOND_SIG_ROTATE_PENDING); | |
356 | if (ret) { | |
357 | PERROR("wakeup rotate pipe"); | |
358 | } | |
359 | } | |
360 | ||
d086f507 JD |
361 | /* |
362 | * This thread is the sighandler for the timer signals. | |
363 | */ | |
364 | void *sessiond_timer_thread(void *data) | |
365 | { | |
366 | int signr; | |
367 | sigset_t mask; | |
368 | siginfo_t info; | |
369 | struct timer_thread_parameters *ctx = data; | |
370 | ||
371 | rcu_register_thread(); | |
372 | rcu_thread_online(); | |
373 | ||
374 | health_register(health_sessiond, HEALTH_SESSIOND_TYPE_TIMER); | |
375 | ||
376 | health_code_update(); | |
377 | ||
378 | /* Only self thread will receive signal mask. */ | |
379 | setmask(&mask); | |
380 | CMM_STORE_SHARED(timer_signal.tid, pthread_self()); | |
381 | ||
382 | while (1) { | |
383 | health_code_update(); | |
384 | ||
385 | health_poll_entry(); | |
386 | signr = sigwaitinfo(&mask, &info); | |
387 | health_poll_exit(); | |
388 | ||
389 | /* | |
390 | * NOTE: cascading conditions are used instead of a switch case | |
391 | * since the use of SIGRTMIN in the definition of the signals' | |
392 | * values prevents the reduction to an integer constant. | |
393 | */ | |
394 | if (signr == -1) { | |
395 | if (errno != EINTR) { | |
396 | PERROR("sigwaitinfo"); | |
397 | } | |
398 | continue; | |
399 | } else if (signr == LTTNG_SESSIOND_SIG_TEARDOWN) { | |
400 | cmm_smp_mb(); | |
401 | CMM_STORE_SHARED(timer_signal.qs_done, 1); | |
402 | cmm_smp_mb(); | |
403 | DBG("Signal timer metadata thread teardown"); | |
404 | } else if (signr == LTTNG_SESSIOND_SIG_EXIT) { | |
405 | goto end; | |
d88744a4 JD |
406 | } else if (signr == LTTNG_SESSIOND_SIG_ROTATE_PENDING) { |
407 | relay_rotation_pending_timer(ctx, info.si_signo, &info); | |
d086f507 JD |
408 | } else { |
409 | ERR("Unexpected signal %d\n", info.si_signo); | |
410 | } | |
411 | } | |
412 | ||
413 | end: | |
414 | DBG("[timer-thread] Exit"); | |
415 | health_unregister(health_sessiond); | |
416 | rcu_thread_offline(); | |
417 | rcu_unregister_thread(); | |
418 | return NULL; | |
419 | } |