| 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 | } |
| 55 | |
| 56 | /* |
| 57 | * This is the same function as consumer_timer_signal_thread_qs, when it |
| 58 | * returns, it means that no timer signr is currently pending or being handled |
| 59 | * by the timer thread. This cannot be called from the timer thread. |
| 60 | */ |
| 61 | static |
| 62 | void sessiond_timer_signal_thread_qs(unsigned int signr) |
| 63 | { |
| 64 | sigset_t pending_set; |
| 65 | int ret; |
| 66 | |
| 67 | /* |
| 68 | * We need to be the only thread interacting with the thread |
| 69 | * that manages signals for teardown synchronization. |
| 70 | */ |
| 71 | pthread_mutex_lock(&timer_signal.lock); |
| 72 | |
| 73 | /* Ensure we don't have any signal queued for this session. */ |
| 74 | for (;;) { |
| 75 | ret = sigemptyset(&pending_set); |
| 76 | if (ret == -1) { |
| 77 | PERROR("sigemptyset"); |
| 78 | } |
| 79 | ret = sigpending(&pending_set); |
| 80 | if (ret == -1) { |
| 81 | PERROR("sigpending"); |
| 82 | } |
| 83 | if (!sigismember(&pending_set, signr)) { |
| 84 | break; |
| 85 | } |
| 86 | caa_cpu_relax(); |
| 87 | } |
| 88 | |
| 89 | /* |
| 90 | * From this point, no new signal handler will be fired that would try to |
| 91 | * access "session". However, we still need to wait for any currently |
| 92 | * executing handler to complete. |
| 93 | */ |
| 94 | cmm_smp_mb(); |
| 95 | CMM_STORE_SHARED(timer_signal.qs_done, 0); |
| 96 | cmm_smp_mb(); |
| 97 | |
| 98 | /* |
| 99 | * Kill with LTTNG_SESSIOND_SIG_TEARDOWN, so signal management thread |
| 100 | * wakes up. |
| 101 | */ |
| 102 | kill(getpid(), LTTNG_SESSIOND_SIG_TEARDOWN); |
| 103 | |
| 104 | while (!CMM_LOAD_SHARED(timer_signal.qs_done)) { |
| 105 | caa_cpu_relax(); |
| 106 | } |
| 107 | cmm_smp_mb(); |
| 108 | |
| 109 | pthread_mutex_unlock(&timer_signal.lock); |
| 110 | } |
| 111 | |
| 112 | /* |
| 113 | * Start a timer on a session that will fire at a given interval |
| 114 | * (timer_interval_us) and fire a given signal (signal). |
| 115 | * |
| 116 | * Returns a negative value on error, 0 if a timer was created, and |
| 117 | * a positive value if no timer was created (not an error). |
| 118 | */ |
| 119 | static |
| 120 | int session_timer_start(timer_t *timer_id, struct ltt_session *session, |
| 121 | unsigned int timer_interval_us, int signal, bool one_shot) |
| 122 | { |
| 123 | int ret = 0, delete_ret; |
| 124 | struct sigevent sev; |
| 125 | struct itimerspec its; |
| 126 | |
| 127 | assert(session); |
| 128 | |
| 129 | sev.sigev_notify = SIGEV_SIGNAL; |
| 130 | sev.sigev_signo = signal; |
| 131 | sev.sigev_value.sival_ptr = session; |
| 132 | ret = timer_create(CLOCKID, &sev, timer_id); |
| 133 | if (ret == -1) { |
| 134 | PERROR("timer_create"); |
| 135 | goto end; |
| 136 | } |
| 137 | |
| 138 | its.it_value.tv_sec = timer_interval_us / 1000000; |
| 139 | its.it_value.tv_nsec = (timer_interval_us % 1000000) * 1000; |
| 140 | if (one_shot) { |
| 141 | its.it_interval.tv_sec = 0; |
| 142 | its.it_interval.tv_nsec = 0; |
| 143 | } else { |
| 144 | its.it_interval.tv_sec = its.it_value.tv_sec; |
| 145 | its.it_interval.tv_nsec = its.it_value.tv_nsec; |
| 146 | } |
| 147 | |
| 148 | ret = timer_settime(*timer_id, 0, &its, NULL); |
| 149 | if (ret == -1) { |
| 150 | PERROR("timer_settime"); |
| 151 | goto error_destroy_timer; |
| 152 | } |
| 153 | goto end; |
| 154 | |
| 155 | error_destroy_timer: |
| 156 | delete_ret = timer_delete(*timer_id); |
| 157 | if (delete_ret == -1) { |
| 158 | PERROR("timer_delete"); |
| 159 | } |
| 160 | |
| 161 | end: |
| 162 | return ret; |
| 163 | } |
| 164 | |
| 165 | static |
| 166 | int session_timer_stop(timer_t *timer_id, int signal) |
| 167 | { |
| 168 | int ret = 0; |
| 169 | |
| 170 | ret = timer_delete(*timer_id); |
| 171 | if (ret == -1) { |
| 172 | PERROR("timer_delete"); |
| 173 | goto end; |
| 174 | } |
| 175 | |
| 176 | sessiond_timer_signal_thread_qs(signal); |
| 177 | *timer_id = 0; |
| 178 | end: |
| 179 | return ret; |
| 180 | } |
| 181 | |
| 182 | /* |
| 183 | * Block the RT signals for the entire process. It must be called from the |
| 184 | * sessiond main before creating the threads |
| 185 | */ |
| 186 | int sessiond_timer_signal_init(void) |
| 187 | { |
| 188 | int ret; |
| 189 | sigset_t mask; |
| 190 | |
| 191 | /* Block signal for entire process, so only our thread processes it. */ |
| 192 | setmask(&mask); |
| 193 | ret = pthread_sigmask(SIG_BLOCK, &mask, NULL); |
| 194 | if (ret) { |
| 195 | errno = ret; |
| 196 | PERROR("pthread_sigmask"); |
| 197 | return -1; |
| 198 | } |
| 199 | return 0; |
| 200 | } |
| 201 | |
| 202 | /* |
| 203 | * This thread is the sighandler for the timer signals. |
| 204 | */ |
| 205 | void *sessiond_timer_thread(void *data) |
| 206 | { |
| 207 | int signr; |
| 208 | sigset_t mask; |
| 209 | siginfo_t info; |
| 210 | struct timer_thread_parameters *ctx = data; |
| 211 | |
| 212 | rcu_register_thread(); |
| 213 | rcu_thread_online(); |
| 214 | |
| 215 | health_register(health_sessiond, HEALTH_SESSIOND_TYPE_TIMER); |
| 216 | |
| 217 | health_code_update(); |
| 218 | |
| 219 | /* Only self thread will receive signal mask. */ |
| 220 | setmask(&mask); |
| 221 | CMM_STORE_SHARED(timer_signal.tid, pthread_self()); |
| 222 | |
| 223 | while (1) { |
| 224 | health_code_update(); |
| 225 | |
| 226 | health_poll_entry(); |
| 227 | signr = sigwaitinfo(&mask, &info); |
| 228 | health_poll_exit(); |
| 229 | |
| 230 | /* |
| 231 | * NOTE: cascading conditions are used instead of a switch case |
| 232 | * since the use of SIGRTMIN in the definition of the signals' |
| 233 | * values prevents the reduction to an integer constant. |
| 234 | */ |
| 235 | if (signr == -1) { |
| 236 | if (errno != EINTR) { |
| 237 | PERROR("sigwaitinfo"); |
| 238 | } |
| 239 | continue; |
| 240 | } else if (signr == LTTNG_SESSIOND_SIG_TEARDOWN) { |
| 241 | cmm_smp_mb(); |
| 242 | CMM_STORE_SHARED(timer_signal.qs_done, 1); |
| 243 | cmm_smp_mb(); |
| 244 | DBG("Signal timer metadata thread teardown"); |
| 245 | } else if (signr == LTTNG_SESSIOND_SIG_EXIT) { |
| 246 | goto end; |
| 247 | } else { |
| 248 | ERR("Unexpected signal %d\n", info.si_signo); |
| 249 | } |
| 250 | } |
| 251 | |
| 252 | end: |
| 253 | DBG("[timer-thread] Exit"); |
| 254 | health_unregister(health_sessiond); |
| 255 | rcu_thread_offline(); |
| 256 | rcu_unregister_thread(); |
| 257 | return NULL; |
| 258 | } |