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,
 192                         executor);
 193 }
 194
 195 static int action_executor_start_session_handler(struct action_executor *executor,
 196                 const struct action_work_item *work_item,
 197                 const struct lttng_action *action)
 198 {
 199         int ret = 0;
 200         const char *session_name;
 201         enum lttng_action_status action_status;
 202         struct ltt_session *session;
 203         enum lttng_error_code cmd_ret;
 204
 205         action_status = lttng_action_start_session_get_session_name(
 206                         action, &session_name);
 207         if (action_status != LTTNG_ACTION_STATUS_OK) {
 208                 ERR("Failed to get session name from `%s` action",
 209                                 get_action_name(action));
 210                 ret = -1;
 211                 goto end;
 212         }
 213
 214         session_lock_list();
 215         session = session_find_by_name(session_name);
 216         if (!session) {
 217                 DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%p`",
 218                                 session_name, get_action_name(action),
 219                     work_item->trigger);
 220                 goto error_unlock_list;
 221         }
 222
 223         session_lock(session);
 224         if (!is_trigger_allowed_for_session(work_item->trigger, session)) {
 225                 goto error_dispose_session;
 226         }
 227
 228         cmd_ret = cmd_start_trace(session);
 229         switch (cmd_ret) {
 230         case LTTNG_OK:
 231                 DBG("Successfully started session `%s` on behalf of trigger `%p`",
 232                                 session_name, work_item->trigger);
 233                 break;
 234         case LTTNG_ERR_TRACE_ALREADY_STARTED:
 235                 DBG("Attempted to start session `%s` on behalf of trigger `%p` but it was already started",
 236                                 session_name, work_item->trigger);
 237                 break;
 238         default:
 239                 WARN("Failed to start session `%s` on behalf of trigger `%p`: %s",
 240                                 session_name, work_item->trigger,
 241                                 lttng_strerror(-cmd_ret));
 242                 break;
 243         }
 244
 245 error_dispose_session:
 246         session_unlock(session);
 247         session_put(session);
 248 error_unlock_list:
 249         session_unlock_list();
 250 end:
 251         return ret;
 252 }
 253
 254 static int action_executor_stop_session_handler(struct action_executor *executor,
 255                 const struct action_work_item *work_item,
 256                 const struct lttng_action *action)
 257 {
 258         int ret = 0;
 259         const char *session_name;
 260         enum lttng_action_status action_status;
 261         struct ltt_session *session;
 262         enum lttng_error_code cmd_ret;
 263
 264         action_status = lttng_action_stop_session_get_session_name(
 265                         action, &session_name);
 266         if (action_status != LTTNG_ACTION_STATUS_OK) {
 267                 ERR("Failed to get session name from `%s` action",
 268                                 get_action_name(action));
 269                 ret = -1;
 270                 goto end;
 271         }
 272
 273         session_lock_list();
 274         session = session_find_by_name(session_name);
 275         if (!session) {
 276                 DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%p`",
 277                                 session_name, get_action_name(action),
 278                     work_item->trigger);
 279                 goto error_unlock_list;
 280         }
 281
 282         session_lock(session);
 283         if (!is_trigger_allowed_for_session(work_item->trigger, session)) {
 284                 goto error_dispose_session;
 285         }
 286
 287         cmd_ret = cmd_stop_trace(session);
 288         switch (cmd_ret) {
 289         case LTTNG_OK:
 290                 DBG("Successfully stopped session `%s` on behalf of trigger `%p`",
 291                                 session_name, work_item->trigger);
 292                 break;
 293         case LTTNG_ERR_TRACE_ALREADY_STOPPED:
 294                 DBG("Attempted to stop session `%s` on behalf of trigger `%p` but it was already stopped",
 295                                 session_name, work_item->trigger);
 296                 break;
 297         default:
 298                 WARN("Failed to stop session `%s` on behalf of trigger `%p`: %s",
 299                                 session_name, work_item->trigger,
 300                                 lttng_strerror(-cmd_ret));
 301                 break;
 302         }
 303
 304 error_dispose_session:
 305         session_unlock(session);
 306         session_put(session);
 307 error_unlock_list:
 308         session_unlock_list();
 309 end:
 310         return ret;
 311 }
 312
 313 static int action_executor_rotate_session_handler(struct action_executor *executor,
 314                 const struct action_work_item *work_item,
 315                 const struct lttng_action *action)
 316 {
 317         int ret = 0;
 318         const char *session_name;
 319         enum lttng_action_status action_status;
 320         struct ltt_session *session;
 321         enum lttng_error_code cmd_ret;
 322
 323         action_status = lttng_action_rotate_session_get_session_name(
 324                         action, &session_name);
 325         if (action_status != LTTNG_ACTION_STATUS_OK) {
 326                 ERR("Failed to get session name from `%s` action",
 327                                 get_action_name(action));
 328                 ret = -1;
 329                 goto end;
 330         }
 331
 332         session_lock_list();
 333         session = session_find_by_name(session_name);
 334         if (!session) {
 335                 DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%p`",
 336                                 session_name, get_action_name(action),
 337                     work_item->trigger);
 338                 goto error_unlock_list;
 339         }
 340
 341         session_lock(session);
 342         if (!is_trigger_allowed_for_session(work_item->trigger, session)) {
 343                 goto error_dispose_session;
 344         }
 345
 346         cmd_ret = cmd_rotate_session(session, NULL, false,
 347                         LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED);
 348         switch (cmd_ret) {
 349         case LTTNG_OK:
 350                 DBG("Successfully started rotation of session `%s` on behalf of trigger `%p`",
 351                                 session_name, work_item->trigger);
 352                 break;
 353         case LTTNG_ERR_ROTATION_PENDING:
 354                 DBG("Attempted to start a rotation of session `%s` on behalf of trigger `%p` but a rotation is already ongoing",
 355                                 session_name, work_item->trigger);
 356                 break;
 357         case LTTNG_ERR_ROTATION_MULTIPLE_AFTER_STOP:
 358         case LTTNG_ERR_ROTATION_AFTER_STOP_CLEAR:
 359                 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",
 360                                 session_name, work_item->trigger);
 361                 break;
 362         default:
 363                 WARN("Failed to start a rotation of session `%s` on behalf of trigger `%p`: %s",
 364                                 session_name, work_item->trigger,
 365                                 lttng_strerror(-cmd_ret));
 366                 break;
 367         }
 368
 369 error_dispose_session:
 370         session_unlock(session);
 371         session_put(session);
 372 error_unlock_list:
 373         session_unlock_list();
 374 end:
 375         return ret;
 376 }
 377
 378 static int action_executor_snapshot_session_handler(struct action_executor *executor,
 379                 const struct action_work_item *work_item,
 380                 const struct lttng_action *action)
 381 {
 382         int ret = 0;
 383         const char *session_name;
 384         enum lttng_action_status action_status;
 385         struct ltt_session *session;
 386         const struct lttng_snapshot_output default_snapshot_output = {
 387                 .max_size = UINT64_MAX,
 388         };
 389         const struct lttng_snapshot_output *snapshot_output =
 390                         &default_snapshot_output;
 391         enum lttng_error_code cmd_ret;
 392
 393         action_status = lttng_action_snapshot_session_get_session_name(
 394                         action, &session_name);
 395         if (action_status != LTTNG_ACTION_STATUS_OK) {
 396                 ERR("Failed to get session name from `%s` action",
 397                                 get_action_name(action));
 398                 ret = -1;
 399                 goto end;
 400         }
 401
 402         action_status = lttng_action_snapshot_session_get_output(
 403                         action, &snapshot_output);
 404         if (action_status != LTTNG_ACTION_STATUS_OK &&
 405                         action_status != LTTNG_ACTION_STATUS_UNSET) {
 406                 ERR("Failed to get output from `%s` action",
 407                                 get_action_name(action));
 408                 ret = -1;
 409                 goto end;
 410         }
 411
 412         session_lock_list();
 413         session = session_find_by_name(session_name);
 414         if (!session) {
 415                 DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%p`",
 416                                 session_name, get_action_name(action),
 417                     work_item->trigger);
 418                 goto error_unlock_list;
 419         }
 420
 421
 422         session_lock(session);
 423         if (!is_trigger_allowed_for_session(work_item->trigger, session)) {
 424                 goto error_dispose_session;
 425         }
 426
 427         cmd_ret = cmd_snapshot_record(session, snapshot_output, 0);
 428         switch (cmd_ret) {
 429         case LTTNG_OK:
 430                 DBG("Successfully recorded snapshot of session `%s` on behalf of trigger `%p`",
 431                                 session_name, work_item->trigger);
 432                 break;
 433         default:
 434                 WARN("Failed to record snapshot of session `%s` on behalf of trigger `%p`: %s",
 435                                 session_name, work_item->trigger,
 436                                 lttng_strerror(-cmd_ret));
 437                 break;
 438         }
 439
 440 error_dispose_session:
 441         session_unlock(session);
 442         session_put(session);
 443 error_unlock_list:
 444         session_unlock_list();
 445 end:
 446         return ret;
 447 }
 448
 449 static int action_executor_group_handler(struct action_executor *executor,
 450                 const struct action_work_item *work_item,
 451                 const struct lttng_action *action_group)
 452 {
 453         int ret = 0;
 454         unsigned int i, count;
 455         enum lttng_action_status action_status;
 456
 457         action_status = lttng_action_group_get_count(action_group, &count);
 458         if (action_status != LTTNG_ACTION_STATUS_OK) {
 459                 /* Fatal error. */
 460                 ERR("Failed to get count of action in action group");
 461                 ret = -1;
 462                 goto end;
 463         }
 464
 465         DBG("Action group has %u action%s", count, count != 1 ? "s" : "");
 466         for (i = 0; i < count; i++) {
 467                 const struct lttng_action *action =
 468                                 lttng_action_group_get_at_index(
 469                                                 action_group, i);
 470
 471                 ret = action_executor_generic_handler(
 472                                 executor, work_item, action);
 473                 if (ret) {
 474                         ERR("Stopping the execution of the action group of trigger `%p` following a fatal error",
 475                                         work_item->trigger);
 476                         goto end;
 477                 }
 478         }
 479 end:
 480         return ret;
 481 }
 482
 483 static int action_executor_generic_handler(struct action_executor *executor,
 484                 const struct action_work_item *work_item,
 485                 const struct lttng_action *action)
 486 {
 487         const enum lttng_action_type action_type = lttng_action_get_type(action);
 488
 489         assert(action_type != LTTNG_ACTION_TYPE_UNKNOWN);
 490
 491         DBG("Executing action `%s` of trigger `%p` action work item %" PRIu64,
 492                         get_action_name(action),
 493                         work_item->trigger,
 494                         work_item->id);
 495
 496         return action_executors[action_type](
 497                         executor, work_item, action);
 498 }
 499
 500 static int action_work_item_execute(struct action_executor *executor,
 501                 struct action_work_item *work_item)
 502 {
 503         int ret;
 504         const struct lttng_action *action =
 505                         lttng_trigger_get_const_action(work_item->trigger);
 506
 507         DBG("Starting execution of action work item %" PRIu64 " of trigger `%p`",
 508                         work_item->id, work_item->trigger);
 509         ret = action_executor_generic_handler(executor, work_item, action);
 510         DBG("Completed execution of action work item %" PRIu64 " of trigger `%p`",
 511                         work_item->id, work_item->trigger);
 512         return ret;
 513 }
 514
 515 static void action_work_item_destroy(struct action_work_item *work_item)
 516 {
 517         lttng_trigger_put(work_item->trigger);
 518         lttng_evaluation_destroy(work_item->evaluation);
 519         notification_client_list_put(work_item->client_list);
 520         free(work_item);
 521 }
 522
 523 static void *action_executor_thread(void *_data)
 524 {
 525         struct action_executor *executor = _data;
 526
 527         assert(executor);
 528
 529         health_register(health_sessiond, HEALTH_SESSIOND_TYPE_ACTION_EXECUTOR);
 530
 531         rcu_register_thread();
 532         rcu_thread_online();
 533
 534         DBG("Entering work execution loop");
 535         pthread_mutex_lock(&executor->work.lock);
 536         while (!executor->should_quit) {
 537                 int ret;
 538                 struct action_work_item *work_item;
 539
 540                 health_code_update();
 541                 if (executor->work.pending_count == 0) {
 542                         health_poll_entry();
 543                         DBG("No work items enqueued, entering wait");
 544                         pthread_cond_wait(&executor->work.cond,
 545                                         &executor->work.lock);
 546                         DBG("Woke-up from wait");
 547                         health_poll_exit();
 548                         continue;
 549                 }
 550
 551                 /* Pop item from front of the listwith work lock held. */
 552                 work_item = cds_list_first_entry(&executor->work.list,
 553                                 struct action_work_item, list_node);
 554                 cds_list_del(&work_item->list_node);
 555                 executor->work.pending_count--;
 556
 557                 /*
 558                  * Work can be performed without holding the work lock,
 559                  * allowing new items to be queued.
 560                  */
 561                 pthread_mutex_unlock(&executor->work.lock);
 562                 ret = action_work_item_execute(executor, work_item);
 563                 action_work_item_destroy(work_item);
 564                 if (ret) {
 565                         /* Fatal error. */
 566                         break;
 567                 }
 568
 569                 health_code_update();
 570                 pthread_mutex_lock(&executor->work.lock);
 571         }
 572
 573         if (executor->should_quit) {
 574                 pthread_mutex_unlock(&executor->work.lock);
 575         }
 576         DBG("Left work execution loop");
 577
 578         health_code_update();
 579
 580         rcu_thread_offline();
 581         rcu_unregister_thread();
 582         health_unregister(health_sessiond);
 583
 584         return NULL;
 585 }
 586
 587 static bool shutdown_action_executor_thread(void *_data)
 588 {
 589         struct action_executor *executor = _data;
 590
 591         executor->should_quit = true;
 592         pthread_cond_signal(&executor->work.cond);
 593         return true;
 594 }
 595
 596 static void clean_up_action_executor_thread(void *_data)
 597 {
 598         struct action_executor *executor = _data;
 599
 600         assert(cds_list_empty(&executor->work.list));
 601
 602         pthread_mutex_destroy(&executor->work.lock);
 603         pthread_cond_destroy(&executor->work.cond);
 604         free(executor);
 605 }
 606
 607 struct action_executor *action_executor_create(
 608                 struct notification_thread_handle *handle)
 609 {
 610         struct action_executor *executor = zmalloc(sizeof(*executor));
 611
 612         if (!executor) {
 613                 goto end;
 614         }
 615
 616         CDS_INIT_LIST_HEAD(&executor->work.list);
 617         pthread_cond_init(&executor->work.cond, NULL);
 618         pthread_mutex_init(&executor->work.lock, NULL);
 619         executor->notification_thread_handle = handle;
 620
 621         executor->thread = lttng_thread_create(THREAD_NAME,
 622                         action_executor_thread, shutdown_action_executor_thread,
 623                         clean_up_action_executor_thread, executor);
 624 end:
 625         return executor;
 626 }
 627
 628 void action_executor_destroy(struct action_executor *executor)
 629 {
 630         struct action_work_item *work_item, *tmp;
 631
 632         /* TODO Wait for work list to drain? */
 633         lttng_thread_shutdown(executor->thread);
 634         pthread_mutex_lock(&executor->work.lock);
 635         if (executor->work.pending_count != 0) {
 636                 WARN("%" PRIu64
 637                         " trigger action%s still queued for execution and will be discarded",
 638                                 executor->work.pending_count,
 639                                 executor->work.pending_count == 1 ? " is" :
 640                                                                     "s are");
 641         }
 642
 643         cds_list_for_each_entry_safe (
 644                         work_item, tmp, &executor->work.list, list_node) {
 645                 WARN("Discarding action work item %" PRIu64
 646                                 " associated to trigger `%p`",
 647                                 work_item->id, work_item->trigger);
 648                 cds_list_del(&work_item->list_node);
 649                 action_work_item_destroy(work_item);
 650         }
 651         pthread_mutex_unlock(&executor->work.lock);
 652         lttng_thread_put(executor->thread);
 653 }
 654
 655 /* RCU read-lock must be held by the caller. */
 656 enum action_executor_status action_executor_enqueue(
 657                 struct action_executor *executor,
 658                 struct lttng_trigger *trigger,
 659                 struct lttng_evaluation *evaluation,
 660                 const struct lttng_credentials *object_creds,
 661                 struct notification_client_list *client_list)
 662 {
 663         enum action_executor_status executor_status = ACTION_EXECUTOR_STATUS_OK;
 664         const uint64_t work_item_id = executor->next_work_item_id++;
 665         struct action_work_item *work_item;
 666         bool signal = false;
 667
 668         pthread_mutex_lock(&executor->work.lock);
 669         /* Check for queue overflow. */
 670         if (executor->work.pending_count >= MAX_QUEUED_WORK_COUNT) {
 671                 /* Most likely spammy, remove if it is the case. */
 672                 DBG("Refusing to enqueue action for trigger `%p` as work item %" PRIu64
 673                     " (overflow)",
 674                                 trigger, work_item_id);
 675                 executor_status = ACTION_EXECUTOR_STATUS_OVERFLOW;
 676                 goto error_unlock;
 677         }
 678
 679         work_item = zmalloc(sizeof(*work_item));
 680         if (!work_item) {
 681                 PERROR("Failed to allocate action executor work item on behalf of trigger `%p`",
 682                                 trigger);
 683                 executor_status = ACTION_EXECUTOR_STATUS_ERROR;
 684                 goto error_unlock;
 685         }
 686
 687         lttng_trigger_get(trigger);
 688         if (client_list) {
 689                 const bool reference_acquired =
 690                                 notification_client_list_get(client_list);
 691
 692                 assert(reference_acquired);
 693         }
 694
 695         *work_item = (typeof(*work_item)){
 696                         .id = work_item_id,
 697                         .trigger = trigger,
 698                         /* Ownership transferred to the work item. */
 699                         .evaluation = evaluation,
 700                         .object_creds = {
 701                                 .is_set = !!object_creds,
 702                                 .value = object_creds ? *object_creds :
 703                                         (typeof(work_item->object_creds.value)) {},
 704                         },
 705                         .client_list = client_list,
 706                         .list_node = CDS_LIST_HEAD_INIT(work_item->list_node),
 707         };
 708
 709         evaluation = NULL;
 710         cds_list_add_tail(&work_item->list_node, &executor->work.list);
 711         executor->work.pending_count++;
 712         DBG("Enqueued action for trigger `%p` as work item %" PRIu64,
 713                         trigger, work_item_id);
 714         signal = true;
 715
 716 error_unlock:
 717         pthread_mutex_unlock(&executor->work.lock);
 718         if (signal) {
 719                 pthread_cond_signal(&executor->work.cond);
 720         }
 721
 722         lttng_evaluation_destroy(evaluation);
 723         return executor_status;
 724 }