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         const enum lttng_action_type action_type = lttng_action_get_type(action);
 108
 109         assert(action_type != LTTNG_ACTION_TYPE_UNKNOWN);
 110
 111         return action_type_names[action_type];
 112 }
 113
 114 /* Check if this trigger allowed to interect with a given session. */
 115 static bool is_trigger_allowed_for_session(const struct lttng_trigger *trigger,
 116                 struct ltt_session *session)
 117 {
 118         bool is_allowed = false;
 119         const struct lttng_credentials session_creds = {
 120                 .uid = LTTNG_OPTIONAL_INIT_VALUE(session->uid),
 121                 .gid = LTTNG_OPTIONAL_INIT_VALUE(session->gid),
 122         };
 123         /* Can never be NULL. */
 124         const struct lttng_credentials *trigger_creds =
 125                         lttng_trigger_get_credentials(trigger);
 126
 127         is_allowed = (lttng_credentials_is_equal_uid(trigger_creds, &session_creds)) ||
 128                         (lttng_credentials_get_uid(trigger_creds) == 0);
 129         if (!is_allowed) {
 130                 WARN("Trigger is not allowed to interact with session `%s`: session uid = %ld, session gid = %ld, trigger uid = %ld",
 131                                 session->name,
 132                                 (long int) session->uid,
 133                                 (long int) session->gid,
 134                                 (long int) lttng_credentials_get_uid(trigger_creds));
 135         }
 136
 137         return is_allowed;
 138 }
 139
 140 static int client_handle_transmission_status(
 141                 struct notification_client *client,
 142                 enum client_transmission_status status,
 143                 void *user_data)
 144 {
 145         int ret = 0;
 146         struct action_executor *executor = user_data;
 147         bool update_communication = true;
 148
 149         switch (status) {
 150         case CLIENT_TRANSMISSION_STATUS_COMPLETE:
 151                 DBG("Successfully sent full notification to client, client_id = %" PRIu64,
 152                                 client->id);
 153                 update_communication = false;
 154                 break;
 155         case CLIENT_TRANSMISSION_STATUS_QUEUED:
 156                 DBG("Queued notification in client outgoing buffer, client_id = %" PRIu64,
 157                                 client->id);
 158                 break;
 159         case CLIENT_TRANSMISSION_STATUS_FAIL:
 160                 DBG("Communication error occurred while sending notification to client, client_id = %" PRIu64,
 161                                 client->id);
 162                 break;
 163         default:
 164                 ERR("Fatal error encoutered while sending notification to client, client_id = %" PRIu64,
 165                                 client->id);
 166                 ret = -1;
 167                 goto end;
 168         }
 169
 170         if (!update_communication) {
 171                 goto end;
 172         }
 173
 174         /* Safe to read client's id without locking as it is immutable. */
 175         ret = notification_thread_client_communication_update(
 176                         executor->notification_thread_handle, client->id,
 177                         status);
 178 end:
 179         return ret;
 180 }
 181
 182 static int action_executor_notify_handler(struct action_executor *executor,
 183                 const struct action_work_item *work_item,
 184                 const struct lttng_action *action)
 185 {
 186         return notification_client_list_send_evaluation(work_item->client_list,
 187                         lttng_trigger_get_const_condition(work_item->trigger),
 188                         work_item->evaluation,
 189                         lttng_trigger_get_credentials(work_item->trigger),
 190                         LTTNG_OPTIONAL_GET_PTR(work_item->object_creds),
 191                         client_handle_transmission_status, executor);
 192 }
 193
 194 static int action_executor_start_session_handler(struct action_executor *executor,
 195                 const struct action_work_item *work_item,
 196                 const struct lttng_action *action)
 197 {
 198         int ret = 0;
 199         const char *session_name;
 200         enum lttng_action_status action_status;
 201         struct ltt_session *session;
 202         enum lttng_error_code cmd_ret;
 203
 204         action_status = lttng_action_start_session_get_session_name(
 205                         action, &session_name);
 206         if (action_status != LTTNG_ACTION_STATUS_OK) {
 207                 ERR("Failed to get session name from `%s` action",
 208                                 get_action_name(action));
 209                 ret = -1;
 210                 goto end;
 211         }
 212
 213         session_lock_list();
 214         session = session_find_by_name(session_name);
 215         if (!session) {
 216                 DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%p`",
 217                                 session_name, get_action_name(action),
 218                     work_item->trigger);
 219                 goto error_unlock_list;
 220         }
 221
 222         session_lock(session);
 223         if (!is_trigger_allowed_for_session(work_item->trigger, session)) {
 224                 goto error_dispose_session;
 225         }
 226
 227         cmd_ret = cmd_start_trace(session);
 228         switch (cmd_ret) {
 229         case LTTNG_OK:
 230                 DBG("Successfully started session `%s` on behalf of trigger `%p`",
 231                                 session_name, work_item->trigger);
 232                 break;
 233         case LTTNG_ERR_TRACE_ALREADY_STARTED:
 234                 DBG("Attempted to start session `%s` on behalf of trigger `%p` but it was already started",
 235                                 session_name, work_item->trigger);
 236                 break;
 237         default:
 238                 WARN("Failed to start session `%s` on behalf of trigger `%p`: %s",
 239                                 session_name, work_item->trigger,
 240                                 lttng_strerror(-cmd_ret));
 241                 break;
 242         }
 243
 244 error_dispose_session:
 245         session_unlock(session);
 246         session_put(session);
 247 error_unlock_list:
 248         session_unlock_list();
 249 end:
 250         return ret;
 251 }
 252
 253 static int action_executor_stop_session_handler(struct action_executor *executor,
 254                 const struct action_work_item *work_item,
 255                 const struct lttng_action *action)
 256 {
 257         int ret = 0;
 258         const char *session_name;
 259         enum lttng_action_status action_status;
 260         struct ltt_session *session;
 261         enum lttng_error_code cmd_ret;
 262
 263         action_status = lttng_action_stop_session_get_session_name(
 264                         action, &session_name);
 265         if (action_status != LTTNG_ACTION_STATUS_OK) {
 266                 ERR("Failed to get session name from `%s` action",
 267                                 get_action_name(action));
 268                 ret = -1;
 269                 goto end;
 270         }
 271
 272         session_lock_list();
 273         session = session_find_by_name(session_name);
 274         if (!session) {
 275                 DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%p`",
 276                                 session_name, get_action_name(action),
 277                     work_item->trigger);
 278                 goto error_unlock_list;
 279         }
 280
 281         session_lock(session);
 282         if (!is_trigger_allowed_for_session(work_item->trigger, session)) {
 283                 goto error_dispose_session;
 284         }
 285
 286         cmd_ret = cmd_stop_trace(session);
 287         switch (cmd_ret) {
 288         case LTTNG_OK:
 289                 DBG("Successfully stopped session `%s` on behalf of trigger `%p`",
 290                                 session_name, work_item->trigger);
 291                 break;
 292         case LTTNG_ERR_TRACE_ALREADY_STOPPED:
 293                 DBG("Attempted to stop session `%s` on behalf of trigger `%p` but it was already stopped",
 294                                 session_name, work_item->trigger);
 295                 break;
 296         default:
 297                 WARN("Failed to stop session `%s` on behalf of trigger `%p`: %s",
 298                                 session_name, work_item->trigger,
 299                                 lttng_strerror(-cmd_ret));
 300                 break;
 301         }
 302
 303 error_dispose_session:
 304         session_unlock(session);
 305         session_put(session);
 306 error_unlock_list:
 307         session_unlock_list();
 308 end:
 309         return ret;
 310 }
 311
 312 static int action_executor_rotate_session_handler(struct action_executor *executor,
 313                 const struct action_work_item *work_item,
 314                 const struct lttng_action *action)
 315 {
 316         int ret = 0;
 317         const char *session_name;
 318         enum lttng_action_status action_status;
 319         struct ltt_session *session;
 320         enum lttng_error_code cmd_ret;
 321
 322         action_status = lttng_action_rotate_session_get_session_name(
 323                         action, &session_name);
 324         if (action_status != LTTNG_ACTION_STATUS_OK) {
 325                 ERR("Failed to get session name from `%s` action",
 326                                 get_action_name(action));
 327                 ret = -1;
 328                 goto end;
 329         }
 330
 331         session_lock_list();
 332         session = session_find_by_name(session_name);
 333         if (!session) {
 334                 DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%p`",
 335                                 session_name, get_action_name(action),
 336                     work_item->trigger);
 337                 goto error_unlock_list;
 338         }
 339
 340         session_lock(session);
 341         if (!is_trigger_allowed_for_session(work_item->trigger, session)) {
 342                 goto error_dispose_session;
 343         }
 344
 345         cmd_ret = cmd_rotate_session(session, NULL, false,
 346                         LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED);
 347         switch (cmd_ret) {
 348         case LTTNG_OK:
 349                 DBG("Successfully started rotation of session `%s` on behalf of trigger `%p`",
 350                                 session_name, work_item->trigger);
 351                 break;
 352         case LTTNG_ERR_ROTATION_PENDING:
 353                 DBG("Attempted to start a rotation of session `%s` on behalf of trigger `%p` but a rotation is already ongoing",
 354                                 session_name, work_item->trigger);
 355                 break;
 356         case LTTNG_ERR_ROTATION_MULTIPLE_AFTER_STOP:
 357         case LTTNG_ERR_ROTATION_AFTER_STOP_CLEAR:
 358                 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",
 359                                 session_name, work_item->trigger);
 360                 break;
 361         default:
 362                 WARN("Failed to start a rotation of session `%s` on behalf of trigger `%p`: %s",
 363                                 session_name, work_item->trigger,
 364                                 lttng_strerror(-cmd_ret));
 365                 break;
 366         }
 367
 368 error_dispose_session:
 369         session_unlock(session);
 370         session_put(session);
 371 error_unlock_list:
 372         session_unlock_list();
 373 end:
 374         return ret;
 375 }
 376
 377 static int action_executor_snapshot_session_handler(struct action_executor *executor,
 378                 const struct action_work_item *work_item,
 379                 const struct lttng_action *action)
 380 {
 381         int ret = 0;
 382         const char *session_name;
 383         enum lttng_action_status action_status;
 384         struct ltt_session *session;
 385         const struct lttng_snapshot_output default_snapshot_output = {
 386                 .max_size = UINT64_MAX,
 387         };
 388         const struct lttng_snapshot_output *snapshot_output =
 389                         &default_snapshot_output;
 390         enum lttng_error_code cmd_ret;
 391
 392         action_status = lttng_action_snapshot_session_get_session_name(
 393                         action, &session_name);
 394         if (action_status != LTTNG_ACTION_STATUS_OK) {
 395                 ERR("Failed to get session name from `%s` action",
 396                                 get_action_name(action));
 397                 ret = -1;
 398                 goto end;
 399         }
 400
 401         action_status = lttng_action_snapshot_session_get_output(
 402                         action, &snapshot_output);
 403         if (action_status != LTTNG_ACTION_STATUS_OK &&
 404                         action_status != LTTNG_ACTION_STATUS_UNSET) {
 405                 ERR("Failed to get output from `%s` action",
 406                                 get_action_name(action));
 407                 ret = -1;
 408                 goto end;
 409         }
 410
 411         session_lock_list();
 412         session = session_find_by_name(session_name);
 413         if (!session) {
 414                 DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%p`",
 415                                 session_name, get_action_name(action),
 416                     work_item->trigger);
 417                 goto error_unlock_list;
 418         }
 419
 420
 421         session_lock(session);
 422         if (!is_trigger_allowed_for_session(work_item->trigger, session)) {
 423                 goto error_dispose_session;
 424         }
 425
 426         cmd_ret = cmd_snapshot_record(session, snapshot_output, 0);
 427         switch (cmd_ret) {
 428         case LTTNG_OK:
 429                 DBG("Successfully recorded snapshot of session `%s` on behalf of trigger `%p`",
 430                                 session_name, work_item->trigger);
 431                 break;
 432         default:
 433                 WARN("Failed to record snapshot of session `%s` on behalf of trigger `%p`: %s",
 434                                 session_name, work_item->trigger,
 435                                 lttng_strerror(-cmd_ret));
 436                 break;
 437         }
 438
 439 error_dispose_session:
 440         session_unlock(session);
 441         session_put(session);
 442 error_unlock_list:
 443         session_unlock_list();
 444 end:
 445         return ret;
 446 }
 447
 448 static int action_executor_group_handler(struct action_executor *executor,
 449                 const struct action_work_item *work_item,
 450                 const struct lttng_action *action_group)
 451 {
 452         int ret = 0;
 453         unsigned int i, count;
 454         enum lttng_action_status action_status;
 455
 456         action_status = lttng_action_group_get_count(action_group, &count);
 457         if (action_status != LTTNG_ACTION_STATUS_OK) {
 458                 /* Fatal error. */
 459                 ERR("Failed to get count of action in action group");
 460                 ret = -1;
 461                 goto end;
 462         }
 463
 464         DBG("Action group has %u action%s", count, count != 1 ? "s" : "");
 465         for (i = 0; i < count; i++) {
 466                 const struct lttng_action *action =
 467                                 lttng_action_group_get_at_index(
 468                                                 action_group, i);
 469
 470                 ret = action_executor_generic_handler(
 471                                 executor, work_item, action);
 472                 if (ret) {
 473                         ERR("Stopping the execution of the action group of trigger `%p` following a fatal error",
 474                                         work_item->trigger);
 475                         goto end;
 476                 }
 477         }
 478 end:
 479         return ret;
 480 }
 481
 482 static int action_executor_generic_handler(struct action_executor *executor,
 483                 const struct action_work_item *work_item,
 484                 const struct lttng_action *action)
 485 {
 486         const enum lttng_action_type action_type = lttng_action_get_type(action);
 487
 488         assert(action_type != LTTNG_ACTION_TYPE_UNKNOWN);
 489
 490         DBG("Executing action `%s` of trigger `%p` action work item %" PRIu64,
 491                         get_action_name(action),
 492                         work_item->trigger,
 493                         work_item->id);
 494
 495         return action_executors[action_type](
 496                         executor, work_item, action);
 497 }
 498
 499 static int action_work_item_execute(struct action_executor *executor,
 500                 struct action_work_item *work_item)
 501 {
 502         int ret;
 503         const struct lttng_action *action =
 504                         lttng_trigger_get_const_action(work_item->trigger);
 505
 506         DBG("Starting execution of action work item %" PRIu64 " of trigger `%p`",
 507                         work_item->id, work_item->trigger);
 508         ret = action_executor_generic_handler(executor, work_item, action);
 509         DBG("Completed execution of action work item %" PRIu64 " of trigger `%p`",
 510                         work_item->id, work_item->trigger);
 511         return ret;
 512 }
 513
 514 static void action_work_item_destroy(struct action_work_item *work_item)
 515 {
 516         lttng_trigger_put(work_item->trigger);
 517         lttng_evaluation_destroy(work_item->evaluation);
 518         notification_client_list_put(work_item->client_list);
 519         free(work_item);
 520 }
 521
 522 static void *action_executor_thread(void *_data)
 523 {
 524         struct action_executor *executor = _data;
 525
 526         assert(executor);
 527
 528         health_register(health_sessiond, HEALTH_SESSIOND_TYPE_ACTION_EXECUTOR);
 529
 530         rcu_register_thread();
 531         rcu_thread_online();
 532
 533         DBG("Entering work execution loop");
 534         pthread_mutex_lock(&executor->work.lock);
 535         while (!executor->should_quit) {
 536                 int ret;
 537                 struct action_work_item *work_item;
 538
 539                 health_code_update();
 540                 if (executor->work.pending_count == 0) {
 541                         health_poll_entry();
 542                         DBG("No work items enqueued, entering wait");
 543                         pthread_cond_wait(&executor->work.cond,
 544                                         &executor->work.lock);
 545                         DBG("Woke-up from wait");
 546                         health_poll_exit();
 547                         continue;
 548                 }
 549
 550                 /* Pop item from front of the list with work lock held. */
 551                 work_item = cds_list_first_entry(&executor->work.list,
 552                                 struct action_work_item, list_node);
 553                 cds_list_del(&work_item->list_node);
 554                 executor->work.pending_count--;
 555
 556                 /*
 557                  * Work can be performed without holding the work lock,
 558                  * allowing new items to be queued.
 559                  */
 560                 pthread_mutex_unlock(&executor->work.lock);
 561                 ret = action_work_item_execute(executor, work_item);
 562                 action_work_item_destroy(work_item);
 563                 if (ret) {
 564                         /* Fatal error. */
 565                         break;
 566                 }
 567
 568                 health_code_update();
 569                 pthread_mutex_lock(&executor->work.lock);
 570         }
 571
 572         if (executor->should_quit) {
 573                 pthread_mutex_unlock(&executor->work.lock);
 574         }
 575         DBG("Left work execution loop");
 576
 577         health_code_update();
 578
 579         rcu_thread_offline();
 580         rcu_unregister_thread();
 581         health_unregister(health_sessiond);
 582
 583         return NULL;
 584 }
 585
 586 static bool shutdown_action_executor_thread(void *_data)
 587 {
 588         struct action_executor *executor = _data;
 589
 590         executor->should_quit = true;
 591         pthread_cond_signal(&executor->work.cond);
 592         return true;
 593 }
 594
 595 static void clean_up_action_executor_thread(void *_data)
 596 {
 597         struct action_executor *executor = _data;
 598
 599         assert(cds_list_empty(&executor->work.list));
 600
 601         pthread_mutex_destroy(&executor->work.lock);
 602         pthread_cond_destroy(&executor->work.cond);
 603         free(executor);
 604 }
 605
 606 struct action_executor *action_executor_create(
 607                 struct notification_thread_handle *handle)
 608 {
 609         struct action_executor *executor = zmalloc(sizeof(*executor));
 610
 611         if (!executor) {
 612                 goto end;
 613         }
 614
 615         CDS_INIT_LIST_HEAD(&executor->work.list);
 616         pthread_cond_init(&executor->work.cond, NULL);
 617         pthread_mutex_init(&executor->work.lock, NULL);
 618         executor->notification_thread_handle = handle;
 619
 620         executor->thread = lttng_thread_create(THREAD_NAME,
 621                         action_executor_thread, shutdown_action_executor_thread,
 622                         clean_up_action_executor_thread, executor);
 623 end:
 624         return executor;
 625 }
 626
 627 void action_executor_destroy(struct action_executor *executor)
 628 {
 629         struct action_work_item *work_item, *tmp;
 630
 631         /* TODO Wait for work list to drain? */
 632         lttng_thread_shutdown(executor->thread);
 633         pthread_mutex_lock(&executor->work.lock);
 634         if (executor->work.pending_count != 0) {
 635                 WARN("%" PRIu64
 636                         " trigger action%s still queued for execution and will be discarded",
 637                                 executor->work.pending_count,
 638                                 executor->work.pending_count == 1 ? " is" :
 639                                                                     "s are");
 640         }
 641
 642         cds_list_for_each_entry_safe (
 643                         work_item, tmp, &executor->work.list, list_node) {
 644                 WARN("Discarding action work item %" PRIu64
 645                                 " associated to trigger `%p`",
 646                                 work_item->id, work_item->trigger);
 647                 cds_list_del(&work_item->list_node);
 648                 action_work_item_destroy(work_item);
 649         }
 650         pthread_mutex_unlock(&executor->work.lock);
 651         lttng_thread_put(executor->thread);
 652 }
 653
 654 /* RCU read-lock must be held by the caller. */
 655 enum action_executor_status action_executor_enqueue(
 656                 struct action_executor *executor,
 657                 struct lttng_trigger *trigger,
 658                 struct lttng_evaluation *evaluation,
 659                 const struct lttng_credentials *object_creds,
 660                 struct notification_client_list *client_list)
 661 {
 662         enum action_executor_status executor_status = ACTION_EXECUTOR_STATUS_OK;
 663         const uint64_t work_item_id = executor->next_work_item_id++;
 664         struct action_work_item *work_item;
 665         bool signal = false;
 666
 667         pthread_mutex_lock(&executor->work.lock);
 668         /* Check for queue overflow. */
 669         if (executor->work.pending_count >= MAX_QUEUED_WORK_COUNT) {
 670                 /* Most likely spammy, remove if it is the case. */
 671                 DBG("Refusing to enqueue action for trigger `%p` as work item %" PRIu64
 672                         " (overflow)", trigger, work_item_id);
 673                 executor_status = ACTION_EXECUTOR_STATUS_OVERFLOW;
 674                 goto error_unlock;
 675         }
 676
 677         work_item = zmalloc(sizeof(*work_item));
 678         if (!work_item) {
 679                 PERROR("Failed to allocate action executor work item on behalf of trigger `%p`",
 680                                 trigger);
 681                 executor_status = ACTION_EXECUTOR_STATUS_ERROR;
 682                 goto error_unlock;
 683         }
 684
 685         lttng_trigger_get(trigger);
 686         if (client_list) {
 687                 const bool reference_acquired =
 688                                 notification_client_list_get(client_list);
 689
 690                 assert(reference_acquired);
 691         }
 692
 693         *work_item = (typeof(*work_item)){
 694                         .id = work_item_id,
 695                         .trigger = trigger,
 696                         /* Ownership transferred to the work item. */
 697                         .evaluation = evaluation,
 698                         .object_creds = {
 699                                 .is_set = !!object_creds,
 700                                 .value = object_creds ? *object_creds :
 701                                         (typeof(work_item->object_creds.value)) {},
 702                         },
 703                         .client_list = client_list,
 704                         .list_node = CDS_LIST_HEAD_INIT(work_item->list_node),
 705         };
 706
 707         evaluation = NULL;
 708         cds_list_add_tail(&work_item->list_node, &executor->work.list);
 709         executor->work.pending_count++;
 710         DBG("Enqueued action for trigger `%p` as work item %" PRIu64,
 711                         trigger, work_item_id);
 712         signal = true;
 713
 714 error_unlock:
 715         pthread_mutex_unlock(&executor->work.lock);
 716         if (signal) {
 717                 pthread_cond_signal(&executor->work.cond);
 718         }
 719
 720         lttng_evaluation_destroy(evaluation);
 721         return executor_status;
 722 }