| 1 | /* |
| 2 | * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca> |
| 3 | * Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 4 | * 2013 - Jérémie Galarneau <jeremie.galarneau@efficios.com> |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify |
| 7 | * it under the terms of the GNU General Public License, version 2 only, |
| 8 | * as published by the Free Software Foundation. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU General Public License along |
| 16 | * with this program; if not, write to the Free Software Foundation, Inc., |
| 17 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| 18 | */ |
| 19 | |
| 20 | #include <common/pipe.h> |
| 21 | #include <common/utils.h> |
| 22 | |
| 23 | #include "manage-kernel.h" |
| 24 | #include "testpoint.h" |
| 25 | #include "health-sessiond.h" |
| 26 | #include "utils.h" |
| 27 | #include "thread.h" |
| 28 | #include "kernel.h" |
| 29 | #include "kernel-consumer.h" |
| 30 | |
| 31 | struct thread_notifiers { |
| 32 | struct lttng_pipe *quit_pipe; |
| 33 | int kernel_poll_pipe_read_fd; |
| 34 | }; |
| 35 | |
| 36 | /* |
| 37 | * Update the kernel poll set of all channel fd available over all tracing |
| 38 | * session. Add the wakeup pipe at the end of the set. |
| 39 | */ |
| 40 | static int update_kernel_poll(struct lttng_poll_event *events) |
| 41 | { |
| 42 | int ret; |
| 43 | struct ltt_kernel_channel *channel; |
| 44 | struct ltt_session *session; |
| 45 | const struct ltt_session_list *session_list = session_get_list(); |
| 46 | |
| 47 | DBG("Updating kernel poll set"); |
| 48 | |
| 49 | session_lock_list(); |
| 50 | cds_list_for_each_entry(session, &session_list->head, list) { |
| 51 | if (!session_get(session)) { |
| 52 | continue; |
| 53 | } |
| 54 | session_lock(session); |
| 55 | if (session->kernel_session == NULL) { |
| 56 | session_unlock(session); |
| 57 | session_put(session); |
| 58 | continue; |
| 59 | } |
| 60 | |
| 61 | cds_list_for_each_entry(channel, |
| 62 | &session->kernel_session->channel_list.head, list) { |
| 63 | /* Add channel fd to the kernel poll set */ |
| 64 | ret = lttng_poll_add(events, channel->fd, LPOLLIN | LPOLLRDNORM); |
| 65 | if (ret < 0) { |
| 66 | session_unlock(session); |
| 67 | session_put(session); |
| 68 | goto error; |
| 69 | } |
| 70 | DBG("Channel fd %d added to kernel set", channel->fd); |
| 71 | } |
| 72 | session_unlock(session); |
| 73 | session_put(session); |
| 74 | } |
| 75 | session_unlock_list(); |
| 76 | |
| 77 | return 0; |
| 78 | |
| 79 | error: |
| 80 | session_unlock_list(); |
| 81 | return -1; |
| 82 | } |
| 83 | |
| 84 | /* |
| 85 | * Find the channel fd from 'fd' over all tracing session. When found, check |
| 86 | * for new channel stream and send those stream fds to the kernel consumer. |
| 87 | * |
| 88 | * Useful for CPU hotplug feature. |
| 89 | */ |
| 90 | static int update_kernel_stream(int fd) |
| 91 | { |
| 92 | int ret = 0; |
| 93 | struct ltt_session *session; |
| 94 | struct ltt_kernel_session *ksess; |
| 95 | struct ltt_kernel_channel *channel; |
| 96 | const struct ltt_session_list *session_list = session_get_list(); |
| 97 | |
| 98 | DBG("Updating kernel streams for channel fd %d", fd); |
| 99 | |
| 100 | session_lock_list(); |
| 101 | cds_list_for_each_entry(session, &session_list->head, list) { |
| 102 | if (!session_get(session)) { |
| 103 | continue; |
| 104 | } |
| 105 | session_lock(session); |
| 106 | if (session->kernel_session == NULL) { |
| 107 | session_unlock(session); |
| 108 | session_put(session); |
| 109 | continue; |
| 110 | } |
| 111 | ksess = session->kernel_session; |
| 112 | |
| 113 | cds_list_for_each_entry(channel, |
| 114 | &ksess->channel_list.head, list) { |
| 115 | struct lttng_ht_iter iter; |
| 116 | struct consumer_socket *socket; |
| 117 | |
| 118 | if (channel->fd != fd) { |
| 119 | continue; |
| 120 | } |
| 121 | DBG("Channel found, updating kernel streams"); |
| 122 | ret = kernel_open_channel_stream(channel); |
| 123 | if (ret < 0) { |
| 124 | goto error; |
| 125 | } |
| 126 | /* Update the stream global counter */ |
| 127 | ksess->stream_count_global += ret; |
| 128 | |
| 129 | /* |
| 130 | * Have we already sent fds to the consumer? If yes, it |
| 131 | * means that tracing is started so it is safe to send |
| 132 | * our updated stream fds. |
| 133 | */ |
| 134 | if (ksess->consumer_fds_sent != 1 |
| 135 | || ksess->consumer == NULL) { |
| 136 | ret = -1; |
| 137 | goto error; |
| 138 | } |
| 139 | |
| 140 | rcu_read_lock(); |
| 141 | cds_lfht_for_each_entry(ksess->consumer->socks->ht, |
| 142 | &iter.iter, socket, node.node) { |
| 143 | pthread_mutex_lock(socket->lock); |
| 144 | ret = kernel_consumer_send_channel_streams(socket, |
| 145 | channel, ksess, |
| 146 | session->output_traces ? 1 : 0); |
| 147 | pthread_mutex_unlock(socket->lock); |
| 148 | if (ret < 0) { |
| 149 | rcu_read_unlock(); |
| 150 | goto error; |
| 151 | } |
| 152 | } |
| 153 | rcu_read_unlock(); |
| 154 | } |
| 155 | session_unlock(session); |
| 156 | session_put(session); |
| 157 | } |
| 158 | session_unlock_list(); |
| 159 | return ret; |
| 160 | |
| 161 | error: |
| 162 | session_unlock(session); |
| 163 | session_put(session); |
| 164 | session_unlock_list(); |
| 165 | return ret; |
| 166 | } |
| 167 | |
| 168 | /* |
| 169 | * This thread manage event coming from the kernel. |
| 170 | * |
| 171 | * Features supported in this thread: |
| 172 | * -) CPU Hotplug |
| 173 | */ |
| 174 | static void *thread_kernel_management(void *data) |
| 175 | { |
| 176 | int ret, i, pollfd, update_poll_flag = 1, err = -1; |
| 177 | uint32_t revents, nb_fd; |
| 178 | char tmp; |
| 179 | struct lttng_poll_event events; |
| 180 | struct thread_notifiers *notifiers = data; |
| 181 | const int quit_pipe_read_fd = lttng_pipe_get_readfd(notifiers->quit_pipe); |
| 182 | |
| 183 | DBG("[thread] Thread manage kernel started"); |
| 184 | |
| 185 | health_register(health_sessiond, HEALTH_SESSIOND_TYPE_KERNEL); |
| 186 | |
| 187 | /* |
| 188 | * This first step of the while is to clean this structure which could free |
| 189 | * non NULL pointers so initialize it before the loop. |
| 190 | */ |
| 191 | lttng_poll_init(&events); |
| 192 | |
| 193 | if (testpoint(sessiond_thread_manage_kernel)) { |
| 194 | goto error_testpoint; |
| 195 | } |
| 196 | |
| 197 | health_code_update(); |
| 198 | |
| 199 | if (testpoint(sessiond_thread_manage_kernel_before_loop)) { |
| 200 | goto error_testpoint; |
| 201 | } |
| 202 | |
| 203 | while (1) { |
| 204 | health_code_update(); |
| 205 | |
| 206 | if (update_poll_flag == 1) { |
| 207 | /* Clean events object. We are about to populate it again. */ |
| 208 | lttng_poll_clean(&events); |
| 209 | |
| 210 | ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC); |
| 211 | if (ret < 0) { |
| 212 | goto error_poll_create; |
| 213 | } |
| 214 | |
| 215 | ret = lttng_poll_add(&events, |
| 216 | notifiers->kernel_poll_pipe_read_fd, |
| 217 | LPOLLIN); |
| 218 | if (ret < 0) { |
| 219 | goto error; |
| 220 | } |
| 221 | |
| 222 | ret = lttng_poll_add(&events, |
| 223 | quit_pipe_read_fd, |
| 224 | LPOLLIN); |
| 225 | if (ret < 0) { |
| 226 | goto error; |
| 227 | } |
| 228 | |
| 229 | /* This will add the available kernel channel if any. */ |
| 230 | ret = update_kernel_poll(&events); |
| 231 | if (ret < 0) { |
| 232 | goto error; |
| 233 | } |
| 234 | update_poll_flag = 0; |
| 235 | } |
| 236 | |
| 237 | DBG("Thread kernel polling"); |
| 238 | |
| 239 | /* Poll infinite value of time */ |
| 240 | restart: |
| 241 | health_poll_entry(); |
| 242 | ret = lttng_poll_wait(&events, -1); |
| 243 | DBG("Thread kernel return from poll on %d fds", |
| 244 | LTTNG_POLL_GETNB(&events)); |
| 245 | health_poll_exit(); |
| 246 | if (ret < 0) { |
| 247 | /* |
| 248 | * Restart interrupted system call. |
| 249 | */ |
| 250 | if (errno == EINTR) { |
| 251 | goto restart; |
| 252 | } |
| 253 | goto error; |
| 254 | } else if (ret == 0) { |
| 255 | /* Should not happen since timeout is infinite */ |
| 256 | ERR("Return value of poll is 0 with an infinite timeout.\n" |
| 257 | "This should not have happened! Continuing..."); |
| 258 | continue; |
| 259 | } |
| 260 | |
| 261 | nb_fd = ret; |
| 262 | |
| 263 | for (i = 0; i < nb_fd; i++) { |
| 264 | /* Fetch once the poll data */ |
| 265 | revents = LTTNG_POLL_GETEV(&events, i); |
| 266 | pollfd = LTTNG_POLL_GETFD(&events, i); |
| 267 | |
| 268 | health_code_update(); |
| 269 | |
| 270 | if (!revents) { |
| 271 | /* No activity for this FD (poll implementation). */ |
| 272 | continue; |
| 273 | } |
| 274 | |
| 275 | if (pollfd == quit_pipe_read_fd) { |
| 276 | err = 0; |
| 277 | goto exit; |
| 278 | } |
| 279 | |
| 280 | /* Check for data on kernel pipe */ |
| 281 | if (revents & LPOLLIN) { |
| 282 | if (pollfd == notifiers->kernel_poll_pipe_read_fd) { |
| 283 | (void) lttng_read(notifiers->kernel_poll_pipe_read_fd, |
| 284 | &tmp, 1); |
| 285 | /* |
| 286 | * Ret value is useless here, if this pipe gets any actions an |
| 287 | * update is required anyway. |
| 288 | */ |
| 289 | update_poll_flag = 1; |
| 290 | continue; |
| 291 | } else { |
| 292 | /* |
| 293 | * New CPU detected by the kernel. Adding kernel stream to |
| 294 | * kernel session and updating the kernel consumer |
| 295 | */ |
| 296 | ret = update_kernel_stream(pollfd); |
| 297 | if (ret < 0) { |
| 298 | continue; |
| 299 | } |
| 300 | break; |
| 301 | } |
| 302 | } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) { |
| 303 | update_poll_flag = 1; |
| 304 | continue; |
| 305 | } else { |
| 306 | ERR("Unexpected poll events %u for sock %d", revents, pollfd); |
| 307 | goto error; |
| 308 | } |
| 309 | } |
| 310 | } |
| 311 | |
| 312 | exit: |
| 313 | error: |
| 314 | lttng_poll_clean(&events); |
| 315 | error_poll_create: |
| 316 | error_testpoint: |
| 317 | if (err) { |
| 318 | health_error(); |
| 319 | ERR("Health error occurred in %s", __func__); |
| 320 | WARN("Kernel thread died unexpectedly. " |
| 321 | "Kernel tracing can continue but CPU hotplug is disabled."); |
| 322 | } |
| 323 | health_unregister(health_sessiond); |
| 324 | DBG("Kernel thread dying"); |
| 325 | return NULL; |
| 326 | } |
| 327 | |
| 328 | static bool shutdown_kernel_management_thread(void *data) |
| 329 | { |
| 330 | struct thread_notifiers *notifiers = data; |
| 331 | const int write_fd = lttng_pipe_get_writefd(notifiers->quit_pipe); |
| 332 | |
| 333 | return notify_thread_pipe(write_fd) == 1; |
| 334 | } |
| 335 | |
| 336 | static void cleanup_kernel_management_thread(void *data) |
| 337 | { |
| 338 | struct thread_notifiers *notifiers = data; |
| 339 | |
| 340 | lttng_pipe_destroy(notifiers->quit_pipe); |
| 341 | free(notifiers); |
| 342 | } |
| 343 | |
| 344 | bool launch_kernel_management_thread(int kernel_poll_pipe_read_fd) |
| 345 | { |
| 346 | struct lttng_pipe *quit_pipe; |
| 347 | struct thread_notifiers *notifiers = NULL; |
| 348 | struct lttng_thread *thread; |
| 349 | |
| 350 | quit_pipe = lttng_pipe_open(FD_CLOEXEC); |
| 351 | if (!quit_pipe) { |
| 352 | goto error; |
| 353 | } |
| 354 | |
| 355 | notifiers = zmalloc(sizeof(*notifiers)); |
| 356 | if (!notifiers) { |
| 357 | goto error; |
| 358 | } |
| 359 | notifiers->quit_pipe = quit_pipe; |
| 360 | notifiers->kernel_poll_pipe_read_fd = kernel_poll_pipe_read_fd; |
| 361 | |
| 362 | thread = lttng_thread_create("Kernel management", |
| 363 | thread_kernel_management, |
| 364 | shutdown_kernel_management_thread, |
| 365 | cleanup_kernel_management_thread, |
| 366 | notifiers); |
| 367 | if (!thread) { |
| 368 | goto error; |
| 369 | } |
| 370 | lttng_thread_put(thread); |
| 371 | return true; |
| 372 | error: |
| 373 | cleanup_kernel_management_thread(notifiers); |
| 374 | return false; |
| 375 | } |