| 1 | /* |
| 2 | * Copyright (C) 2012 - Julien Desfossez <julien.desfossez@efficios.com> |
| 3 | * David Goulet <dgoulet@efficios.com> |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License, version 2 only, as |
| 7 | * published by the Free Software Foundation. |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, but WITHOUT |
| 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
| 12 | * more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License along with |
| 15 | * this program; if not, write to the Free Software Foundation, Inc., 51 |
| 16 | * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| 17 | */ |
| 18 | |
| 19 | #define _GNU_SOURCE |
| 20 | #include <assert.h> |
| 21 | #include <inttypes.h> |
| 22 | #include <signal.h> |
| 23 | |
| 24 | #include <common/common.h> |
| 25 | |
| 26 | #include "consumer-timer.h" |
| 27 | #include "ust-consumer/ust-consumer.h" |
| 28 | |
| 29 | static struct timer_signal_data timer_signal = { |
| 30 | .tid = 0, |
| 31 | .setup_done = 0, |
| 32 | .qs_done = 0, |
| 33 | .lock = PTHREAD_MUTEX_INITIALIZER, |
| 34 | }; |
| 35 | |
| 36 | /* |
| 37 | * Set custom signal mask to current thread. |
| 38 | */ |
| 39 | static void setmask(sigset_t *mask) |
| 40 | { |
| 41 | int ret; |
| 42 | |
| 43 | ret = sigemptyset(mask); |
| 44 | if (ret) { |
| 45 | PERROR("sigemptyset"); |
| 46 | } |
| 47 | ret = sigaddset(mask, LTTNG_CONSUMER_SIG_SWITCH); |
| 48 | if (ret) { |
| 49 | PERROR("sigaddset"); |
| 50 | } |
| 51 | ret = sigaddset(mask, LTTNG_CONSUMER_SIG_TEARDOWN); |
| 52 | if (ret) { |
| 53 | PERROR("sigaddset"); |
| 54 | } |
| 55 | } |
| 56 | |
| 57 | /* |
| 58 | * Execute action on a timer switch. |
| 59 | * |
| 60 | * Beware: metadata_switch_timer() should *never* take a mutex also held |
| 61 | * while consumer_timer_switch_stop() is called. It would result in |
| 62 | * deadlocks. |
| 63 | */ |
| 64 | static void metadata_switch_timer(struct lttng_consumer_local_data *ctx, |
| 65 | int sig, siginfo_t *si, void *uc) |
| 66 | { |
| 67 | int ret; |
| 68 | struct lttng_consumer_channel *channel; |
| 69 | |
| 70 | channel = si->si_value.sival_ptr; |
| 71 | assert(channel); |
| 72 | |
| 73 | if (channel->switch_timer_error) { |
| 74 | return; |
| 75 | } |
| 76 | |
| 77 | DBG("Switch timer for channel %" PRIu64, channel->key); |
| 78 | switch (ctx->type) { |
| 79 | case LTTNG_CONSUMER32_UST: |
| 80 | case LTTNG_CONSUMER64_UST: |
| 81 | /* |
| 82 | * Locks taken by lttng_ustconsumer_request_metadata(): |
| 83 | * - metadata_socket_lock |
| 84 | * - Calling lttng_ustconsumer_recv_metadata(): |
| 85 | * - channel->metadata_cache->lock |
| 86 | * - Calling consumer_metadata_cache_flushed(): |
| 87 | * - channel->timer_lock |
| 88 | * - channel->metadata_cache->lock |
| 89 | * |
| 90 | * Ensure that neither consumer_data.lock nor |
| 91 | * channel->lock are taken within this function, since |
| 92 | * they are held while consumer_timer_switch_stop() is |
| 93 | * called. |
| 94 | */ |
| 95 | ret = lttng_ustconsumer_request_metadata(ctx, channel, 1); |
| 96 | if (ret < 0) { |
| 97 | channel->switch_timer_error = 1; |
| 98 | } |
| 99 | break; |
| 100 | case LTTNG_CONSUMER_KERNEL: |
| 101 | case LTTNG_CONSUMER_UNKNOWN: |
| 102 | assert(0); |
| 103 | break; |
| 104 | } |
| 105 | } |
| 106 | |
| 107 | static |
| 108 | void consumer_timer_signal_thread_qs(unsigned int signr) |
| 109 | { |
| 110 | sigset_t pending_set; |
| 111 | int ret; |
| 112 | |
| 113 | /* |
| 114 | * We need to be the only thread interacting with the thread |
| 115 | * that manages signals for teardown synchronization. |
| 116 | */ |
| 117 | pthread_mutex_lock(&timer_signal.lock); |
| 118 | |
| 119 | /* Ensure we don't have any signal queued for this channel. */ |
| 120 | for (;;) { |
| 121 | ret = sigemptyset(&pending_set); |
| 122 | if (ret == -1) { |
| 123 | PERROR("sigemptyset"); |
| 124 | } |
| 125 | ret = sigpending(&pending_set); |
| 126 | if (ret == -1) { |
| 127 | PERROR("sigpending"); |
| 128 | } |
| 129 | if (!sigismember(&pending_set, LTTNG_CONSUMER_SIG_SWITCH)) { |
| 130 | break; |
| 131 | } |
| 132 | caa_cpu_relax(); |
| 133 | } |
| 134 | |
| 135 | /* |
| 136 | * From this point, no new signal handler will be fired that would try to |
| 137 | * access "chan". However, we still need to wait for any currently |
| 138 | * executing handler to complete. |
| 139 | */ |
| 140 | cmm_smp_mb(); |
| 141 | CMM_STORE_SHARED(timer_signal.qs_done, 0); |
| 142 | cmm_smp_mb(); |
| 143 | |
| 144 | /* |
| 145 | * Kill with LTTNG_CONSUMER_SIG_TEARDOWN, so signal management thread wakes |
| 146 | * up. |
| 147 | */ |
| 148 | kill(getpid(), LTTNG_CONSUMER_SIG_TEARDOWN); |
| 149 | |
| 150 | while (!CMM_LOAD_SHARED(timer_signal.qs_done)) { |
| 151 | caa_cpu_relax(); |
| 152 | } |
| 153 | cmm_smp_mb(); |
| 154 | |
| 155 | pthread_mutex_unlock(&timer_signal.lock); |
| 156 | } |
| 157 | |
| 158 | /* |
| 159 | * Set the timer for periodical metadata flush. |
| 160 | */ |
| 161 | void consumer_timer_switch_start(struct lttng_consumer_channel *channel, |
| 162 | unsigned int switch_timer_interval) |
| 163 | { |
| 164 | int ret; |
| 165 | struct sigevent sev; |
| 166 | struct itimerspec its; |
| 167 | |
| 168 | assert(channel); |
| 169 | assert(channel->key); |
| 170 | |
| 171 | if (switch_timer_interval == 0) { |
| 172 | return; |
| 173 | } |
| 174 | |
| 175 | sev.sigev_notify = SIGEV_SIGNAL; |
| 176 | sev.sigev_signo = LTTNG_CONSUMER_SIG_SWITCH; |
| 177 | sev.sigev_value.sival_ptr = channel; |
| 178 | ret = timer_create(CLOCKID, &sev, &channel->switch_timer); |
| 179 | if (ret == -1) { |
| 180 | PERROR("timer_create"); |
| 181 | } |
| 182 | channel->switch_timer_enabled = 1; |
| 183 | |
| 184 | its.it_value.tv_sec = switch_timer_interval / 1000000; |
| 185 | its.it_value.tv_nsec = switch_timer_interval % 1000000; |
| 186 | its.it_interval.tv_sec = its.it_value.tv_sec; |
| 187 | its.it_interval.tv_nsec = its.it_value.tv_nsec; |
| 188 | |
| 189 | ret = timer_settime(channel->switch_timer, 0, &its, NULL); |
| 190 | if (ret == -1) { |
| 191 | PERROR("timer_settime"); |
| 192 | } |
| 193 | } |
| 194 | |
| 195 | /* |
| 196 | * Stop and delete timer. |
| 197 | */ |
| 198 | void consumer_timer_switch_stop(struct lttng_consumer_channel *channel) |
| 199 | { |
| 200 | int ret; |
| 201 | |
| 202 | assert(channel); |
| 203 | |
| 204 | ret = timer_delete(channel->switch_timer); |
| 205 | if (ret == -1) { |
| 206 | PERROR("timer_delete"); |
| 207 | } |
| 208 | |
| 209 | consumer_timer_signal_thread_qs(LTTNG_CONSUMER_SIG_SWITCH); |
| 210 | |
| 211 | channel->switch_timer = 0; |
| 212 | channel->switch_timer_enabled = 0; |
| 213 | } |
| 214 | |
| 215 | /* |
| 216 | * Block the RT signals for the entire process. It must be called from the |
| 217 | * consumer main before creating the threads |
| 218 | */ |
| 219 | void consumer_signal_init(void) |
| 220 | { |
| 221 | int ret; |
| 222 | sigset_t mask; |
| 223 | |
| 224 | /* Block signal for entire process, so only our thread processes it. */ |
| 225 | setmask(&mask); |
| 226 | ret = pthread_sigmask(SIG_BLOCK, &mask, NULL); |
| 227 | if (ret) { |
| 228 | errno = ret; |
| 229 | PERROR("pthread_sigmask"); |
| 230 | } |
| 231 | } |
| 232 | |
| 233 | /* |
| 234 | * This thread is the sighandler for signals LTTNG_CONSUMER_SIG_SWITCH and |
| 235 | * LTTNG_CONSUMER_SIG_TEARDOWN that are emitted by the periodic timer to check |
| 236 | * if new metadata is available. |
| 237 | */ |
| 238 | void *consumer_timer_metadata_thread(void *data) |
| 239 | { |
| 240 | int signr; |
| 241 | sigset_t mask; |
| 242 | siginfo_t info; |
| 243 | struct lttng_consumer_local_data *ctx = data; |
| 244 | |
| 245 | /* Only self thread will receive signal mask. */ |
| 246 | setmask(&mask); |
| 247 | CMM_STORE_SHARED(timer_signal.tid, pthread_self()); |
| 248 | |
| 249 | while (1) { |
| 250 | signr = sigwaitinfo(&mask, &info); |
| 251 | if (signr == -1) { |
| 252 | if (errno != EINTR) { |
| 253 | PERROR("sigwaitinfo"); |
| 254 | } |
| 255 | continue; |
| 256 | } else if (signr == LTTNG_CONSUMER_SIG_SWITCH) { |
| 257 | metadata_switch_timer(ctx, info.si_signo, &info, NULL); |
| 258 | } else if (signr == LTTNG_CONSUMER_SIG_TEARDOWN) { |
| 259 | cmm_smp_mb(); |
| 260 | CMM_STORE_SHARED(timer_signal.qs_done, 1); |
| 261 | cmm_smp_mb(); |
| 262 | DBG("Signal timer metadata thread teardown"); |
| 263 | } else { |
| 264 | ERR("Unexpected signal %d\n", info.si_signo); |
| 265 | } |
| 266 | } |
| 267 | |
| 268 | return NULL; |
| 269 | } |