src/bin/lttng-sessiond/action-executor.c

   1 /*
   2  * Copyright (C) 2020 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-only
   5  *
   6  */
   7
   8 #include "action-executor.h"
   9 #include "cmd.h"
  10 #include "health-sessiond.h"
  11 #include "lttng-sessiond.h"
  12 #include "notification-thread-internal.h"
  13 #include "session.h"
  14 #include "thread.h"
  15 #include <common/macros.h>
  16 #include <common/optional.h>
  17 #include <lttng/action/action-internal.h>
  18 #include <lttng/action/group.h>
  19 #include <lttng/action/notify.h>
  20 #include <lttng/action/rotate-session.h>
  21 #include <lttng/action/snapshot-session.h>
  22 #include <lttng/action/start-session.h>
  23 #include <lttng/action/stop-session.h>
  24 #include <lttng/condition/evaluation.h>
  25 #include <lttng/lttng-error.h>
  26 #include <lttng/trigger/trigger-internal.h>
  27 #include <pthread.h>
  28 #include <stdbool.h>
  29 #include <stddef.h>
  30 #include <urcu/list.h>
  31
  32 #define THREAD_NAME "Action Executor"
  33 #define MAX_QUEUED_WORK_COUNT 8192
  34
  35 struct action_work_item {
  36         uint64_t id;
  37         struct lttng_trigger *trigger;
  38         struct lttng_evaluation *evaluation;
  39         struct notification_client_list *client_list;
  40         LTTNG_OPTIONAL(struct lttng_credentials) object_creds;
  41         struct cds_list_head list_node;
  42 };
  43
  44 struct action_executor {
  45         struct lttng_thread *thread;
  46         struct notification_thread_handle *notification_thread_handle;
  47         struct {
  48                 uint64_t pending_count;
  49                 struct cds_list_head list;
  50                 pthread_cond_t cond;
  51                 pthread_mutex_t lock;
  52         } work;
  53         bool should_quit;
  54         uint64_t next_work_item_id;
  55 };
  56
  57 /*
  58  * Only return non-zero on a fatal error that should shut down the action
  59  * executor.
  60  */
  61 typedef int (*action_executor_handler)(struct action_executor *executor,
  62                 const struct action_work_item *,
  63                 const struct lttng_action *action);
  64
  65 static int action_executor_notify_handler(struct action_executor *executor,
  66                 const struct action_work_item *,
  67                 const struct lttng_action *);
  68 static int action_executor_start_session_handler(struct action_executor *executor,
  69                 const struct action_work_item *,
  70                 const struct lttng_action *);
  71 static int action_executor_stop_session_handler(struct action_executor *executor,
  72                 const struct action_work_item *,
  73                 const struct lttng_action *);
  74 static int action_executor_rotate_session_handler(struct action_executor *executor,
  75                 const struct action_work_item *,
  76                 const struct lttng_action *);
  77 static int action_executor_snapshot_session_handler(struct action_executor *executor,
  78                 const struct action_work_item *,
  79                 const struct lttng_action *);
  80 static int action_executor_group_handler(struct action_executor *executor,
  81                 const struct action_work_item *,
  82                 const struct lttng_action *);
  83 static int action_executor_generic_handler(struct action_executor *executor,
  84                 const struct action_work_item *,
  85                 const struct lttng_action *);
  86
  87 static const action_executor_handler action_executors[] = {
  88         [LTTNG_ACTION_TYPE_NOTIFY] = action_executor_notify_handler,
  89         [LTTNG_ACTION_TYPE_START_SESSION] = action_executor_start_session_handler,
  90         [LTTNG_ACTION_TYPE_STOP_SESSION] = action_executor_stop_session_handler,
  91         [LTTNG_ACTION_TYPE_ROTATE_SESSION] = action_executor_rotate_session_handler,
  92         [LTTNG_ACTION_TYPE_SNAPSHOT_SESSION] = action_executor_snapshot_session_handler,
  93         [LTTNG_ACTION_TYPE_GROUP] = action_executor_group_handler,
  94 };
  95
  96 static const char *action_type_names[] = {
  97         [LTTNG_ACTION_TYPE_NOTIFY] = "Notify",
  98         [LTTNG_ACTION_TYPE_START_SESSION] = "Start session",
  99         [LTTNG_ACTION_TYPE_STOP_SESSION] = "Stop session",
 100         [LTTNG_ACTION_TYPE_ROTATE_SESSION] = "Rotate session",
 101         [LTTNG_ACTION_TYPE_SNAPSHOT_SESSION] = "Snapshot session",
 102         [LTTNG_ACTION_TYPE_GROUP] = "Group",
 103 };
 104
 105 static const char *get_action_name(const struct lttng_action *action)
 106 {
 107         return action_type_names[lttng_action_get_type(action)];
 108 }
 109
 110 /* Check if this trigger allowed to interect with a given session. */
 111 static bool is_trigger_allowed_for_session(const struct lttng_trigger *trigger,
 112                 struct ltt_session *session)
 113 {
 114         bool is_allowed = false;
 115         const struct lttng_credentials session_creds = {
 116                 .uid = LTTNG_OPTIONAL_INIT_VALUE(session->uid),
 117                 .gid = LTTNG_OPTIONAL_INIT_VALUE(session->gid),
 118         };
 119         /* Can never be NULL. */
 120         const struct lttng_credentials *trigger_creds =
 121                         lttng_trigger_get_credentials(trigger);
 122
 123         is_allowed = (lttng_credentials_is_equal_uid(trigger_creds, &session_creds)) ||
 124                         (lttng_credentials_get_uid(trigger_creds) == 0);
 125         if (!is_allowed) {
 126                 WARN("Trigger is not allowed to interact with session `%s`: session uid = %ld, session gid = %ld, trigger uid = %ld",
 127                                 session->name,
 128                                 (long int) session->uid,
 129                                 (long int) session->gid,
 130                                 (long int) lttng_credentials_get_uid(trigger_creds));
 131         }
 132
 133         return is_allowed;
 134 }
 135
 136 static int client_handle_transmission_status(
 137                 struct notification_client *client,
 138                 enum client_transmission_status status,
 139                 void *user_data)
 140 {
 141         int ret = 0;
 142         struct action_executor *executor = user_data;
 143         bool update_communication = true;
 144
 145         switch (status) {
 146         case CLIENT_TRANSMISSION_STATUS_COMPLETE:
 147                 DBG("Successfully sent full notification to client, client_id = %" PRIu64,
 148                                 client->id);
 149                 update_communication = false;
 150                 break;
 151         case CLIENT_TRANSMISSION_STATUS_QUEUED:
 152                 DBG("Queued notification in client outgoing buffer, client_id = %" PRIu64,
 153                                 client->id);
 154                 break;
 155         case CLIENT_TRANSMISSION_STATUS_FAIL:
 156                 DBG("Communication error occurred while sending notification to client, client_id = %" PRIu64,
 157                                 client->id);
 158                 break;
 159         default:
 160                 ERR("Fatal error encoutered while sending notification to client, client_id = %" PRIu64,
 161                                 client->id);
 162                 ret = -1;
 163                 goto end;
 164         }
 165
 166         if (!update_communication) {
 167                 goto end;
 168         }
 169
 170         /* Safe to read client's id without locking as it is immutable. */
 171         ret = notification_thread_client_communication_update(
 172                         executor->notification_thread_handle, client->id,
 173                         status);
 174 end:
 175         return ret;
 176 }
 177
 178 static int action_executor_notify_handler(struct action_executor *executor,
 179                 const struct action_work_item *work_item,
 180                 const struct lttng_action *action)
 181 {
 182         return notification_client_list_send_evaluation(work_item->client_list,
 183                         lttng_trigger_get_const_condition(work_item->trigger),
 184                         work_item->evaluation,
 185                         lttng_trigger_get_credentials(work_item->trigger),
 186                         LTTNG_OPTIONAL_GET_PTR(work_item->object_creds),
 187                         client_handle_transmission_status,
 188                         executor);
 189 }
 190
 191 static int action_executor_start_session_handler(struct action_executor *executor,
 192                 const struct action_work_item *work_item,
 193                 const struct lttng_action *action)
 194 {
 195         int ret = 0;
 196         const char *session_name;
 197         enum lttng_action_status action_status;
 198         struct ltt_session *session;
 199         enum lttng_error_code cmd_ret;
 200
 201         action_status = lttng_action_start_session_get_session_name(
 202                         action, &session_name);
 203         if (action_status != LTTNG_ACTION_STATUS_OK) {
 204                 ERR("Failed to get session name from `%s` action",
 205                                 get_action_name(action));
 206                 ret = -1;
 207                 goto end;
 208         }
 209
 210         session_lock_list();
 211         session = session_find_by_name(session_name);
 212         if (!session) {
 213                 DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%p`",
 214                                 session_name, get_action_name(action),
 215                     work_item->trigger);
 216                 goto error_unlock_list;
 217         }
 218
 219         session_lock(session);
 220         if (!is_trigger_allowed_for_session(work_item->trigger, session)) {
 221                 goto error_dispose_session;
 222         }
 223
 224         cmd_ret = cmd_start_trace(session);
 225         switch (cmd_ret) {
 226         case LTTNG_OK:
 227                 DBG("Successfully started session `%s` on behalf of trigger `%p`",
 228                                 session_name, work_item->trigger);
 229                 break;
 230         case LTTNG_ERR_TRACE_ALREADY_STARTED:
 231                 DBG("Attempted to start session `%s` on behalf of trigger `%p` but it was already started",
 232                                 session_name, work_item->trigger);
 233                 break;
 234         default:
 235                 WARN("Failed to start session `%s` on behalf of trigger `%p`: %s",
 236                                 session_name, work_item->trigger,
 237                                 lttng_strerror(-cmd_ret));
 238                 break;
 239         }
 240
 241 error_dispose_session:
 242         session_unlock(session);
 243         session_put(session);
 244 error_unlock_list:
 245         session_unlock_list();
 246 end:
 247         return ret;
 248 }
 249
 250 static int action_executor_stop_session_handler(struct action_executor *executor,
 251                 const struct action_work_item *work_item,
 252                 const struct lttng_action *action)
 253 {
 254         int ret = 0;
 255         const char *session_name;
 256         enum lttng_action_status action_status;
 257         struct ltt_session *session;
 258         enum lttng_error_code cmd_ret;
 259
 260         action_status = lttng_action_stop_session_get_session_name(
 261                         action, &session_name);
 262         if (action_status != LTTNG_ACTION_STATUS_OK) {
 263                 ERR("Failed to get session name from `%s` action",
 264                                 get_action_name(action));
 265                 ret = -1;
 266                 goto end;
 267         }
 268
 269         session_lock_list();
 270         session = session_find_by_name(session_name);
 271         if (!session) {
 272                 DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%p`",
 273                                 session_name, get_action_name(action),
 274                     work_item->trigger);
 275                 goto error_unlock_list;
 276         }
 277
 278         session_lock(session);
 279         if (!is_trigger_allowed_for_session(work_item->trigger, session)) {
 280                 goto error_dispose_session;
 281         }
 282
 283         cmd_ret = cmd_stop_trace(session);
 284         switch (cmd_ret) {
 285         case LTTNG_OK:
 286                 DBG("Successfully stopped session `%s` on behalf of trigger `%p`",
 287                                 session_name, work_item->trigger);
 288                 break;
 289         case LTTNG_ERR_TRACE_ALREADY_STOPPED:
 290                 DBG("Attempted to stop session `%s` on behalf of trigger `%p` but it was already stopped",
 291                                 session_name, work_item->trigger);
 292                 break;
 293         default:
 294                 WARN("Failed to stop session `%s` on behalf of trigger `%p`: %s",
 295                                 session_name, work_item->trigger,
 296                                 lttng_strerror(-cmd_ret));
 297                 break;
 298         }
 299
 300 error_dispose_session:
 301         session_unlock(session);
 302         session_put(session);
 303 error_unlock_list:
 304         session_unlock_list();
 305 end:
 306         return ret;
 307 }
 308
 309 static int action_executor_rotate_session_handler(struct action_executor *executor,
 310                 const struct action_work_item *work_item,
 311                 const struct lttng_action *action)
 312 {
 313         int ret = 0;
 314         const char *session_name;
 315         enum lttng_action_status action_status;
 316         struct ltt_session *session;
 317         enum lttng_error_code cmd_ret;
 318
 319         action_status = lttng_action_rotate_session_get_session_name(
 320                         action, &session_name);
 321         if (action_status != LTTNG_ACTION_STATUS_OK) {
 322                 ERR("Failed to get session name from `%s` action",
 323                                 get_action_name(action));
 324                 ret = -1;
 325                 goto end;
 326         }
 327
 328         session_lock_list();
 329         session = session_find_by_name(session_name);
 330         if (!session) {
 331                 DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%p`",
 332                                 session_name, get_action_name(action),
 333                     work_item->trigger);
 334                 goto error_unlock_list;
 335         }
 336
 337         session_lock(session);
 338         if (!is_trigger_allowed_for_session(work_item->trigger, session)) {
 339                 goto error_dispose_session;
 340         }
 341
 342         cmd_ret = cmd_rotate_session(session, NULL, false,
 343                         LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED);
 344         switch (cmd_ret) {
 345         case LTTNG_OK:
 346                 DBG("Successfully started rotation of session `%s` on behalf of trigger `%p`",
 347                                 session_name, work_item->trigger);
 348                 break;
 349         case LTTNG_ERR_ROTATION_PENDING:
 350                 DBG("Attempted to start a rotation of session `%s` on behalf of trigger `%p` but a rotation is already ongoing",
 351                                 session_name, work_item->trigger);
 352                 break;
 353         case LTTNG_ERR_ROTATION_MULTIPLE_AFTER_STOP:
 354         case LTTNG_ERR_ROTATION_AFTER_STOP_CLEAR:
 355                 DBG("Attempted to start a rotation of session `%s` on behalf of trigger `%p` but a rotation has already been completed since the last stop or clear",
 356                                 session_name, work_item->trigger);
 357                 break;
 358         default:
 359                 WARN("Failed to start a rotation of session `%s` on behalf of trigger `%p`: %s",
 360                                 session_name, work_item->trigger,
 361                                 lttng_strerror(-cmd_ret));
 362                 break;
 363         }
 364
 365 error_dispose_session:
 366         session_unlock(session);
 367         session_put(session);
 368 error_unlock_list:
 369         session_unlock_list();
 370 end:
 371         return ret;
 372 }
 373
 374 static int action_executor_snapshot_session_handler(struct action_executor *executor,
 375                 const struct action_work_item *work_item,
 376                 const struct lttng_action *action)
 377 {
 378         int ret = 0;
 379         const char *session_name;
 380         enum lttng_action_status action_status;
 381         struct ltt_session *session;
 382         const struct lttng_snapshot_output default_snapshot_output = {
 383                 .max_size = UINT64_MAX,
 384         };
 385         const struct lttng_snapshot_output *snapshot_output =
 386                         &default_snapshot_output;
 387         enum lttng_error_code cmd_ret;
 388
 389         action_status = lttng_action_snapshot_session_get_session_name(
 390                         action, &session_name);
 391         if (action_status != LTTNG_ACTION_STATUS_OK) {
 392                 ERR("Failed to get session name from `%s` action",
 393                                 get_action_name(action));
 394                 ret = -1;
 395                 goto end;
 396         }
 397
 398         action_status = lttng_action_snapshot_session_get_output(
 399                         action, &snapshot_output);
 400         if (action_status != LTTNG_ACTION_STATUS_OK &&
 401                         action_status != LTTNG_ACTION_STATUS_UNSET) {
 402                 ERR("Failed to get output from `%s` action",
 403                                 get_action_name(action));
 404                 ret = -1;
 405                 goto end;
 406         }
 407
 408         session_lock_list();
 409         session = session_find_by_name(session_name);
 410         if (!session) {
 411                 DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%p`",
 412                                 session_name, get_action_name(action),
 413                     work_item->trigger);
 414                 goto error_unlock_list;
 415         }
 416
 417
 418         session_lock(session);
 419         if (!is_trigger_allowed_for_session(work_item->trigger, session)) {
 420                 goto error_dispose_session;
 421         }
 422
 423         cmd_ret = cmd_snapshot_record(session, snapshot_output, 0);
 424         switch (cmd_ret) {
 425         case LTTNG_OK:
 426                 DBG("Successfully recorded snapshot of session `%s` on behalf of trigger `%p`",
 427                                 session_name, work_item->trigger);
 428                 break;
 429         default:
 430                 WARN("Failed to record snapshot of session `%s` on behalf of trigger `%p`: %s",
 431                                 session_name, work_item->trigger,
 432                                 lttng_strerror(-cmd_ret));
 433                 break;
 434         }
 435
 436 error_dispose_session:
 437         session_unlock(session);
 438         session_put(session);
 439 error_unlock_list:
 440         session_unlock_list();
 441 end:
 442         return ret;
 443 }
 444
 445 static int action_executor_group_handler(struct action_executor *executor,
 446                 const struct action_work_item *work_item,
 447                 const struct lttng_action *action_group)
 448 {
 449         int ret = 0;
 450         unsigned int i, count;
 451         enum lttng_action_status action_status;
 452
 453         action_status = lttng_action_group_get_count(action_group, &count);
 454         if (action_status != LTTNG_ACTION_STATUS_OK) {
 455                 /* Fatal error. */
 456                 ERR("Failed to get count of action in action group");
 457                 ret = -1;
 458                 goto end;
 459         }
 460
 461         DBG("Action group has %u action%s", count, count != 1 ? "s" : "");
 462         for (i = 0; i < count; i++) {
 463                 const struct lttng_action *action =
 464                                 lttng_action_group_get_at_index(
 465                                                 action_group, i);
 466
 467                 ret = action_executor_generic_handler(
 468                                 executor, work_item, action);
 469                 if (ret) {
 470                         ERR("Stopping the execution of the action group of trigger `%p` following a fatal error",
 471                                         work_item->trigger);
 472                         goto end;
 473                 }
 474         }
 475 end:
 476         return ret;
 477 }
 478
 479 static int action_executor_generic_handler(struct action_executor *executor,
 480                 const struct action_work_item *work_item,
 481                 const struct lttng_action *action)
 482 {
 483         DBG("Executing action `%s` of trigger `%p` action work item %" PRIu64,
 484                         get_action_name(action),
 485                         work_item->trigger,
 486                         work_item->id);
 487
 488         return action_executors[lttng_action_get_type(action)](
 489                         executor, work_item, action);
 490 }
 491
 492 static int action_work_item_execute(struct action_executor *executor,
 493                 struct action_work_item *work_item)
 494 {
 495         int ret;
 496         const struct lttng_action *action =
 497                         lttng_trigger_get_const_action(work_item->trigger);
 498
 499         DBG("Starting execution of action work item %" PRIu64 " of trigger `%p`",
 500                         work_item->id, work_item->trigger);
 501         ret = action_executor_generic_handler(executor, work_item, action);
 502         DBG("Completed execution of action work item %" PRIu64 " of trigger `%p`",
 503                         work_item->id, work_item->trigger);
 504         return ret;
 505 }
 506
 507 static void action_work_item_destroy(struct action_work_item *work_item)
 508 {
 509         lttng_trigger_put(work_item->trigger);
 510         lttng_evaluation_destroy(work_item->evaluation);
 511         notification_client_list_put(work_item->client_list);
 512         free(work_item);
 513 }
 514
 515 static void *action_executor_thread(void *_data)
 516 {
 517         struct action_executor *executor = _data;
 518
 519         assert(executor);
 520
 521         health_register(health_sessiond, HEALTH_SESSIOND_TYPE_ACTION_EXECUTOR);
 522
 523         rcu_register_thread();
 524         rcu_thread_online();
 525
 526         DBG("Entering work execution loop");
 527         pthread_mutex_lock(&executor->work.lock);
 528         while (!executor->should_quit) {
 529                 int ret;
 530                 struct action_work_item *work_item;
 531
 532                 health_code_update();
 533                 if (executor->work.pending_count == 0) {
 534                         health_poll_entry();
 535                         DBG("No work items enqueued, entering wait");
 536                         pthread_cond_wait(&executor->work.cond,
 537                                         &executor->work.lock);
 538                         DBG("Woke-up from wait");
 539                         health_poll_exit();
 540                         continue;
 541                 }
 542
 543                 /* Pop item from front of the listwith work lock held. */
 544                 work_item = cds_list_first_entry(&executor->work.list,
 545                                 struct action_work_item, list_node);
 546                 cds_list_del(&work_item->list_node);
 547                 executor->work.pending_count--;
 548
 549                 /*
 550                  * Work can be performed without holding the work lock,
 551                  * allowing new items to be queued.
 552                  */
 553                 pthread_mutex_unlock(&executor->work.lock);
 554                 ret = action_work_item_execute(executor, work_item);
 555                 action_work_item_destroy(work_item);
 556                 if (ret) {
 557                         /* Fatal error. */
 558                         break;
 559                 }
 560
 561                 health_code_update();
 562                 pthread_mutex_lock(&executor->work.lock);
 563         }
 564
 565         if (executor->should_quit) {
 566                 pthread_mutex_unlock(&executor->work.lock);
 567         }
 568         DBG("Left work execution loop");
 569
 570         health_code_update();
 571
 572         rcu_thread_offline();
 573         rcu_unregister_thread();
 574         health_unregister(health_sessiond);
 575
 576         return NULL;
 577 }
 578
 579 static bool shutdown_action_executor_thread(void *_data)
 580 {
 581         struct action_executor *executor = _data;
 582
 583         executor->should_quit = true;
 584         pthread_cond_signal(&executor->work.cond);
 585         return true;
 586 }
 587
 588 static void clean_up_action_executor_thread(void *_data)
 589 {
 590         struct action_executor *executor = _data;
 591
 592         assert(cds_list_empty(&executor->work.list));
 593
 594         pthread_mutex_destroy(&executor->work.lock);
 595         pthread_cond_destroy(&executor->work.cond);
 596         free(executor);
 597 }
 598
 599 struct action_executor *action_executor_create(
 600                 struct notification_thread_handle *handle)
 601 {
 602         struct action_executor *executor = zmalloc(sizeof(*executor));
 603
 604         if (!executor) {
 605                 goto end;
 606         }
 607
 608         CDS_INIT_LIST_HEAD(&executor->work.list);
 609         pthread_cond_init(&executor->work.cond, NULL);
 610         pthread_mutex_init(&executor->work.lock, NULL);
 611         executor->notification_thread_handle = handle;
 612
 613         executor->thread = lttng_thread_create(THREAD_NAME,
 614                         action_executor_thread, shutdown_action_executor_thread,
 615                         clean_up_action_executor_thread, executor);
 616 end:
 617         return executor;
 618 }
 619
 620 void action_executor_destroy(struct action_executor *executor)
 621 {
 622         struct action_work_item *work_item, *tmp;
 623
 624         /* TODO Wait for work list to drain? */
 625         lttng_thread_shutdown(executor->thread);
 626         pthread_mutex_lock(&executor->work.lock);
 627         if (executor->work.pending_count != 0) {
 628                 WARN("%" PRIu64
 629                         " trigger action%s still queued for execution and will be discarded",
 630                                 executor->work.pending_count,
 631                                 executor->work.pending_count == 1 ? " is" :
 632                                                                     "s are");
 633         }
 634
 635         cds_list_for_each_entry_safe (
 636                         work_item, tmp, &executor->work.list, list_node) {
 637                 WARN("Discarding action work item %" PRIu64
 638                                 " associated to trigger `%p`",
 639                                 work_item->id, work_item->trigger);
 640                 cds_list_del(&work_item->list_node);
 641                 action_work_item_destroy(work_item);
 642         }
 643         pthread_mutex_unlock(&executor->work.lock);
 644         lttng_thread_put(executor->thread);
 645 }
 646
 647 /* RCU read-lock must be held by the caller. */
 648 enum action_executor_status action_executor_enqueue(
 649                 struct action_executor *executor,
 650                 struct lttng_trigger *trigger,
 651                 struct lttng_evaluation *evaluation,
 652                 const struct lttng_credentials *object_creds,
 653                 struct notification_client_list *client_list)
 654 {
 655         enum action_executor_status executor_status = ACTION_EXECUTOR_STATUS_OK;
 656         const uint64_t work_item_id = executor->next_work_item_id++;
 657         struct action_work_item *work_item;
 658         bool signal = false;
 659
 660         pthread_mutex_lock(&executor->work.lock);
 661         /* Check for queue overflow. */
 662         if (executor->work.pending_count >= MAX_QUEUED_WORK_COUNT) {
 663                 /* Most likely spammy, remove if it is the case. */
 664                 DBG("Refusing to enqueue action for trigger `%p` as work item %" PRIu64
 665                     " (overflow)",
 666                                 trigger, work_item_id);
 667                 executor_status = ACTION_EXECUTOR_STATUS_OVERFLOW;
 668                 goto error_unlock;
 669         }
 670
 671         work_item = zmalloc(sizeof(*work_item));
 672         if (!work_item) {
 673                 PERROR("Failed to allocate action executor work item on behalf of trigger `%p`",
 674                                 trigger);
 675                 executor_status = ACTION_EXECUTOR_STATUS_ERROR;
 676                 goto error_unlock;
 677         }
 678
 679         lttng_trigger_get(trigger);
 680         if (client_list) {
 681                 const bool reference_acquired =
 682                                 notification_client_list_get(client_list);
 683
 684                 assert(reference_acquired);
 685         }
 686
 687         *work_item = (typeof(*work_item)){
 688                         .id = work_item_id,
 689                         .trigger = trigger,
 690                         /* Ownership transferred to the work item. */
 691                         .evaluation = evaluation,
 692                         .object_creds = {
 693                                 .is_set = !!object_creds,
 694                                 .value = object_creds ? *object_creds :
 695                                         (typeof(work_item->object_creds.value)) {},
 696                         },
 697                         .client_list = client_list,
 698                         .list_node = CDS_LIST_HEAD_INIT(work_item->list_node),
 699         };
 700
 701         evaluation = NULL;
 702         cds_list_add_tail(&work_item->list_node, &executor->work.list);
 703         executor->work.pending_count++;
 704         DBG("Enqueued action for trigger `%p` as work item %" PRIu64,
 705                         trigger, work_item_id);
 706         signal = true;
 707
 708 error_unlock:
 709         pthread_mutex_unlock(&executor->work.lock);
 710         if (signal) {
 711                 pthread_cond_signal(&executor->work.cond);
 712         }
 713
 714         lttng_evaluation_destroy(evaluation);
 715         return executor_status;
 716 }