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-internal.h>
  20 #include <lttng/action/notify.h>
  21 #include <lttng/action/rotate-session.h>
  22 #include <lttng/action/snapshot-session.h>
  23 #include <lttng/action/start-session.h>
  24 #include <lttng/action/stop-session.h>
  25 #include <lttng/condition/evaluation.h>
  26 #include <lttng/condition/on-event-internal.h>
  27 #include <lttng/lttng-error.h>
  28 #include <lttng/trigger/trigger-internal.h>
  29 #include <pthread.h>
  30 #include <stdbool.h>
  31 #include <stddef.h>
  32 #include <urcu/list.h>
  33
  34 #define THREAD_NAME "Action Executor"
  35 #define MAX_QUEUED_WORK_COUNT 8192
  36
  37 struct action_work_item {
  38         uint64_t id;
  39         struct lttng_trigger *trigger;
  40         struct lttng_evaluation *evaluation;
  41         struct notification_client_list *client_list;
  42         LTTNG_OPTIONAL(struct lttng_credentials) object_creds;
  43         struct cds_list_head list_node;
  44 };
  45
  46 struct action_executor {
  47         struct lttng_thread *thread;
  48         struct notification_thread_handle *notification_thread_handle;
  49         struct {
  50                 uint64_t pending_count;
  51                 struct cds_list_head list;
  52                 pthread_cond_t cond;
  53                 pthread_mutex_t lock;
  54         } work;
  55         bool should_quit;
  56         uint64_t next_work_item_id;
  57 };
  58
  59 /*
  60  * Only return non-zero on a fatal error that should shut down the action
  61  * executor.
  62  */
  63 typedef int (*action_executor_handler)(struct action_executor *executor,
  64                 const struct action_work_item *,
  65                 const struct lttng_action *action);
  66
  67 static int action_executor_notify_handler(struct action_executor *executor,
  68                 const struct action_work_item *,
  69                 const struct lttng_action *);
  70 static int action_executor_start_session_handler(struct action_executor *executor,
  71                 const struct action_work_item *,
  72                 const struct lttng_action *);
  73 static int action_executor_stop_session_handler(struct action_executor *executor,
  74                 const struct action_work_item *,
  75                 const struct lttng_action *);
  76 static int action_executor_rotate_session_handler(struct action_executor *executor,
  77                 const struct action_work_item *,
  78                 const struct lttng_action *);
  79 static int action_executor_snapshot_session_handler(struct action_executor *executor,
  80                 const struct action_work_item *,
  81                 const struct lttng_action *);
  82 static int action_executor_group_handler(struct action_executor *executor,
  83                 const struct action_work_item *,
  84                 const struct lttng_action *);
  85 static int action_executor_generic_handler(struct action_executor *executor,
  86                 const struct action_work_item *,
  87                 const struct lttng_action *);
  88
  89 static const action_executor_handler action_executors[] = {
  90         [LTTNG_ACTION_TYPE_NOTIFY] = action_executor_notify_handler,
  91         [LTTNG_ACTION_TYPE_START_SESSION] = action_executor_start_session_handler,
  92         [LTTNG_ACTION_TYPE_STOP_SESSION] = action_executor_stop_session_handler,
  93         [LTTNG_ACTION_TYPE_ROTATE_SESSION] = action_executor_rotate_session_handler,
  94         [LTTNG_ACTION_TYPE_SNAPSHOT_SESSION] = action_executor_snapshot_session_handler,
  95         [LTTNG_ACTION_TYPE_GROUP] = action_executor_group_handler,
  96 };
  97
  98 static const char *action_type_names[] = {
  99         [LTTNG_ACTION_TYPE_NOTIFY] = "Notify",
 100         [LTTNG_ACTION_TYPE_START_SESSION] = "Start session",
 101         [LTTNG_ACTION_TYPE_STOP_SESSION] = "Stop session",
 102         [LTTNG_ACTION_TYPE_ROTATE_SESSION] = "Rotate session",
 103         [LTTNG_ACTION_TYPE_SNAPSHOT_SESSION] = "Snapshot session",
 104         [LTTNG_ACTION_TYPE_GROUP] = "Group",
 105 };
 106
 107 static const char *get_action_name(const struct lttng_action *action)
 108 {
 109         const enum lttng_action_type action_type = lttng_action_get_type(action);
 110
 111         assert(action_type != LTTNG_ACTION_TYPE_UNKNOWN);
 112
 113         return action_type_names[action_type];
 114 }
 115
 116 /* Check if this trigger allowed to interect with a given session. */
 117 static bool is_trigger_allowed_for_session(const struct lttng_trigger *trigger,
 118                 struct ltt_session *session)
 119 {
 120         bool is_allowed = false;
 121         const struct lttng_credentials session_creds = {
 122                 .uid = LTTNG_OPTIONAL_INIT_VALUE(session->uid),
 123                 .gid = LTTNG_OPTIONAL_INIT_VALUE(session->gid),
 124         };
 125         /* Can never be NULL. */
 126         const struct lttng_credentials *trigger_creds =
 127                         lttng_trigger_get_credentials(trigger);
 128
 129         is_allowed = (lttng_credentials_is_equal_uid(trigger_creds, &session_creds)) ||
 130                         (lttng_credentials_get_uid(trigger_creds) == 0);
 131         if (!is_allowed) {
 132                 WARN("Trigger is not allowed to interact with session `%s`: session uid = %ld, session gid = %ld, trigger uid = %ld",
 133                                 session->name,
 134                                 (long int) session->uid,
 135                                 (long int) session->gid,
 136                                 (long int) lttng_credentials_get_uid(trigger_creds));
 137         }
 138
 139         return is_allowed;
 140 }
 141
 142 static const char *get_trigger_name(const struct lttng_trigger *trigger)
 143 {
 144         const char *trigger_name;
 145         enum lttng_trigger_status trigger_status;
 146
 147         trigger_status = lttng_trigger_get_name(trigger, &trigger_name);
 148         assert(trigger_status == LTTNG_TRIGGER_STATUS_OK);
 149
 150         return trigger_name;
 151 }
 152
 153 static int client_handle_transmission_status(
 154                 struct notification_client *client,
 155                 enum client_transmission_status status,
 156                 void *user_data)
 157 {
 158         int ret = 0;
 159         struct action_executor *executor = user_data;
 160         bool update_communication = true;
 161
 162         switch (status) {
 163         case CLIENT_TRANSMISSION_STATUS_COMPLETE:
 164                 DBG("Successfully sent full notification to client, client_id = %" PRIu64,
 165                                 client->id);
 166                 update_communication = false;
 167                 break;
 168         case CLIENT_TRANSMISSION_STATUS_QUEUED:
 169                 DBG("Queued notification in client outgoing buffer, client_id = %" PRIu64,
 170                                 client->id);
 171                 break;
 172         case CLIENT_TRANSMISSION_STATUS_FAIL:
 173                 DBG("Communication error occurred while sending notification to client, client_id = %" PRIu64,
 174                                 client->id);
 175                 break;
 176         default:
 177                 ERR("Fatal error encoutered while sending notification to client, client_id = %" PRIu64,
 178                                 client->id);
 179                 ret = -1;
 180                 goto end;
 181         }
 182
 183         if (!update_communication) {
 184                 goto end;
 185         }
 186
 187         /* Safe to read client's id without locking as it is immutable. */
 188         ret = notification_thread_client_communication_update(
 189                         executor->notification_thread_handle, client->id,
 190                         status);
 191 end:
 192         return ret;
 193 }
 194
 195 static int action_executor_notify_handler(struct action_executor *executor,
 196                 const struct action_work_item *work_item,
 197                 const struct lttng_action *action)
 198 {
 199         return notification_client_list_send_evaluation(work_item->client_list,
 200                         lttng_trigger_get_const_condition(work_item->trigger),
 201                         work_item->evaluation,
 202                         lttng_trigger_get_credentials(work_item->trigger),
 203                         work_item->object_creds.is_set ?
 204                                         &(work_item->object_creds.value) :
 205                                         NULL,
 206                         client_handle_transmission_status, executor);
 207 }
 208
 209 static int action_executor_start_session_handler(struct action_executor *executor,
 210                 const struct action_work_item *work_item,
 211                 const struct lttng_action *action)
 212 {
 213         int ret = 0;
 214         const char *session_name;
 215         enum lttng_action_status action_status;
 216         struct ltt_session *session;
 217         enum lttng_error_code cmd_ret;
 218
 219         action_status = lttng_action_start_session_get_session_name(
 220                         action, &session_name);
 221         if (action_status != LTTNG_ACTION_STATUS_OK) {
 222                 ERR("Failed to get session name from `%s` action",
 223                                 get_action_name(action));
 224                 ret = -1;
 225                 goto end;
 226         }
 227
 228         session_lock_list();
 229         session = session_find_by_name(session_name);
 230         if (!session) {
 231                 DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%s`",
 232                                 session_name, get_action_name(action),
 233                                 get_trigger_name(work_item->trigger));
 234                 goto error_unlock_list;
 235         }
 236
 237         session_lock(session);
 238         if (!is_trigger_allowed_for_session(work_item->trigger, session)) {
 239                 goto error_dispose_session;
 240         }
 241
 242         cmd_ret = cmd_start_trace(session);
 243         switch (cmd_ret) {
 244         case LTTNG_OK:
 245                 DBG("Successfully started session `%s` on behalf of trigger `%s`",
 246                                 session_name, get_trigger_name(work_item->trigger));
 247                 break;
 248         case LTTNG_ERR_TRACE_ALREADY_STARTED:
 249                 DBG("Attempted to start session `%s` on behalf of trigger `%s` but it was already started",
 250                                 session_name, get_trigger_name(work_item->trigger));
 251                 break;
 252         default:
 253                 WARN("Failed to start session `%s` on behalf of trigger `%s`: %s",
 254                                 session_name, get_trigger_name(work_item->trigger),
 255                                 lttng_strerror(-cmd_ret));
 256                 break;
 257         }
 258
 259 error_dispose_session:
 260         session_unlock(session);
 261         session_put(session);
 262 error_unlock_list:
 263         session_unlock_list();
 264 end:
 265         return ret;
 266 }
 267
 268 static int action_executor_stop_session_handler(struct action_executor *executor,
 269                 const struct action_work_item *work_item,
 270                 const struct lttng_action *action)
 271 {
 272         int ret = 0;
 273         const char *session_name;
 274         enum lttng_action_status action_status;
 275         struct ltt_session *session;
 276         enum lttng_error_code cmd_ret;
 277
 278         action_status = lttng_action_stop_session_get_session_name(
 279                         action, &session_name);
 280         if (action_status != LTTNG_ACTION_STATUS_OK) {
 281                 ERR("Failed to get session name from `%s` action",
 282                                 get_action_name(action));
 283                 ret = -1;
 284                 goto end;
 285         }
 286
 287         session_lock_list();
 288         session = session_find_by_name(session_name);
 289         if (!session) {
 290                 DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%s`",
 291                                 session_name, get_action_name(action),
 292                                 get_trigger_name(work_item->trigger));
 293                 goto error_unlock_list;
 294         }
 295
 296         session_lock(session);
 297         if (!is_trigger_allowed_for_session(work_item->trigger, session)) {
 298                 goto error_dispose_session;
 299         }
 300
 301         cmd_ret = cmd_stop_trace(session);
 302         switch (cmd_ret) {
 303         case LTTNG_OK:
 304                 DBG("Successfully stopped session `%s` on behalf of trigger `%s`",
 305                                 session_name, get_trigger_name(work_item->trigger));
 306                 break;
 307         case LTTNG_ERR_TRACE_ALREADY_STOPPED:
 308                 DBG("Attempted to stop session `%s` on behalf of trigger `%s` but it was already stopped",
 309                                 session_name, get_trigger_name(work_item->trigger));
 310                 break;
 311         default:
 312                 WARN("Failed to stop session `%s` on behalf of trigger `%s`: %s",
 313                                 session_name, get_trigger_name(work_item->trigger),
 314                                 lttng_strerror(-cmd_ret));
 315                 break;
 316         }
 317
 318 error_dispose_session:
 319         session_unlock(session);
 320         session_put(session);
 321 error_unlock_list:
 322         session_unlock_list();
 323 end:
 324         return ret;
 325 }
 326
 327 static int action_executor_rotate_session_handler(struct action_executor *executor,
 328                 const struct action_work_item *work_item,
 329                 const struct lttng_action *action)
 330 {
 331         int ret = 0;
 332         const char *session_name;
 333         enum lttng_action_status action_status;
 334         struct ltt_session *session;
 335         enum lttng_error_code cmd_ret;
 336
 337         action_status = lttng_action_rotate_session_get_session_name(
 338                         action, &session_name);
 339         if (action_status != LTTNG_ACTION_STATUS_OK) {
 340                 ERR("Failed to get session name from `%s` action",
 341                                 get_action_name(action));
 342                 ret = -1;
 343                 goto end;
 344         }
 345
 346         session_lock_list();
 347         session = session_find_by_name(session_name);
 348         if (!session) {
 349                 DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%s`",
 350                                 session_name, get_action_name(action),
 351                                 get_trigger_name(work_item->trigger));
 352                 goto error_unlock_list;
 353         }
 354
 355         session_lock(session);
 356         if (!is_trigger_allowed_for_session(work_item->trigger, session)) {
 357                 goto error_dispose_session;
 358         }
 359
 360         cmd_ret = cmd_rotate_session(session, NULL, false,
 361                         LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED);
 362         switch (cmd_ret) {
 363         case LTTNG_OK:
 364                 DBG("Successfully started rotation of session `%s` on behalf of trigger `%s`",
 365                                 session_name, get_trigger_name(work_item->trigger));
 366                 break;
 367         case LTTNG_ERR_ROTATION_PENDING:
 368                 DBG("Attempted to start a rotation of session `%s` on behalf of trigger `%s` but a rotation is already ongoing",
 369                                 session_name, get_trigger_name(work_item->trigger));
 370                 break;
 371         case LTTNG_ERR_ROTATION_MULTIPLE_AFTER_STOP:
 372         case LTTNG_ERR_ROTATION_AFTER_STOP_CLEAR:
 373                 DBG("Attempted to start a rotation of session `%s` on behalf of trigger `%s` but a rotation has already been completed since the last stop or clear",
 374                                 session_name, get_trigger_name(work_item->trigger));
 375                 break;
 376         default:
 377                 WARN("Failed to start a rotation of session `%s` on behalf of trigger `%s`: %s",
 378                                 session_name, get_trigger_name(work_item->trigger),
 379                                 lttng_strerror(-cmd_ret));
 380                 break;
 381         }
 382
 383 error_dispose_session:
 384         session_unlock(session);
 385         session_put(session);
 386 error_unlock_list:
 387         session_unlock_list();
 388 end:
 389         return ret;
 390 }
 391
 392 static int action_executor_snapshot_session_handler(struct action_executor *executor,
 393                 const struct action_work_item *work_item,
 394                 const struct lttng_action *action)
 395 {
 396         int ret = 0;
 397         const char *session_name;
 398         enum lttng_action_status action_status;
 399         struct ltt_session *session;
 400         const struct lttng_snapshot_output default_snapshot_output = {
 401                 .max_size = UINT64_MAX,
 402         };
 403         const struct lttng_snapshot_output *snapshot_output =
 404                         &default_snapshot_output;
 405         enum lttng_error_code cmd_ret;
 406
 407         action_status = lttng_action_snapshot_session_get_session_name(
 408                         action, &session_name);
 409         if (action_status != LTTNG_ACTION_STATUS_OK) {
 410                 ERR("Failed to get session name from `%s` action",
 411                                 get_action_name(action));
 412                 ret = -1;
 413                 goto end;
 414         }
 415
 416         action_status = lttng_action_snapshot_session_get_output(
 417                         action, &snapshot_output);
 418         if (action_status != LTTNG_ACTION_STATUS_OK &&
 419                         action_status != LTTNG_ACTION_STATUS_UNSET) {
 420                 ERR("Failed to get output from `%s` action",
 421                                 get_action_name(action));
 422                 ret = -1;
 423                 goto end;
 424         }
 425
 426         session_lock_list();
 427         session = session_find_by_name(session_name);
 428         if (!session) {
 429                 DBG("Failed to find session `%s` by name while executing `%s` action of trigger `%s`",
 430                                 session_name, get_action_name(action),
 431                                 get_trigger_name(work_item->trigger));
 432                 goto error_unlock_list;
 433         }
 434
 435
 436         session_lock(session);
 437         if (!is_trigger_allowed_for_session(work_item->trigger, session)) {
 438                 goto error_dispose_session;
 439         }
 440
 441         cmd_ret = cmd_snapshot_record(session, snapshot_output, 0);
 442         switch (cmd_ret) {
 443         case LTTNG_OK:
 444                 DBG("Successfully recorded snapshot of session `%s` on behalf of trigger `%s`",
 445                                 session_name, get_trigger_name(work_item->trigger));
 446                 break;
 447         default:
 448                 WARN("Failed to record snapshot of session `%s` on behalf of trigger `%s`: %s",
 449                                 session_name, get_trigger_name(work_item->trigger),
 450                                 lttng_strerror(-cmd_ret));
 451                 break;
 452         }
 453
 454 error_dispose_session:
 455         session_unlock(session);
 456         session_put(session);
 457 error_unlock_list:
 458         session_unlock_list();
 459 end:
 460         return ret;
 461 }
 462
 463 static int action_executor_group_handler(struct action_executor *executor,
 464                 const struct action_work_item *work_item,
 465                 const struct lttng_action *action_group)
 466 {
 467         int ret = 0;
 468         unsigned int i, count;
 469         enum lttng_action_status action_status;
 470
 471         action_status = lttng_action_group_get_count(action_group, &count);
 472         if (action_status != LTTNG_ACTION_STATUS_OK) {
 473                 /* Fatal error. */
 474                 ERR("Failed to get count of action in action group");
 475                 ret = -1;
 476                 goto end;
 477         }
 478
 479         DBG("Action group has %u action%s", count, count != 1 ? "s" : "");
 480         for (i = 0; i < count; i++) {
 481                 const struct lttng_action *action =
 482                                 lttng_action_group_get_at_index(
 483                                                 action_group, i);
 484
 485                 ret = action_executor_generic_handler(
 486                                 executor, work_item, action);
 487                 if (ret) {
 488                         ERR("Stopping the execution of the action group of trigger `%s` following a fatal error",
 489                                         get_trigger_name(work_item->trigger));
 490                         goto end;
 491                 }
 492         }
 493 end:
 494         return ret;
 495 }
 496
 497 static int action_executor_generic_handler(struct action_executor *executor,
 498                 const struct action_work_item *work_item,
 499                 const struct lttng_action *action)
 500 {
 501         const enum lttng_action_type action_type = lttng_action_get_type(action);
 502
 503         assert(action_type != LTTNG_ACTION_TYPE_UNKNOWN);
 504
 505         DBG("Executing action `%s` of trigger `%s` action work item %" PRIu64,
 506                         get_action_name(action),
 507                         get_trigger_name(work_item->trigger),
 508                         work_item->id);
 509
 510         return action_executors[action_type](
 511                         executor, work_item, action);
 512 }
 513
 514 static int action_work_item_execute(struct action_executor *executor,
 515                 struct action_work_item *work_item)
 516 {
 517         int ret;
 518         const struct lttng_action *action =
 519                         lttng_trigger_get_const_action(work_item->trigger);
 520
 521         DBG("Starting execution of action work item %" PRIu64 " of trigger `%s`",
 522                         work_item->id, get_trigger_name(work_item->trigger));
 523         ret = action_executor_generic_handler(executor, work_item, action);
 524         DBG("Completed execution of action work item %" PRIu64 " of trigger `%s`",
 525                         work_item->id, get_trigger_name(work_item->trigger));
 526         return ret;
 527 }
 528
 529 static void action_work_item_destroy(struct action_work_item *work_item)
 530 {
 531         lttng_trigger_put(work_item->trigger);
 532         lttng_evaluation_destroy(work_item->evaluation);
 533         notification_client_list_put(work_item->client_list);
 534         free(work_item);
 535 }
 536
 537 static void *action_executor_thread(void *_data)
 538 {
 539         struct action_executor *executor = _data;
 540
 541         assert(executor);
 542
 543         health_register(health_sessiond, HEALTH_SESSIOND_TYPE_ACTION_EXECUTOR);
 544
 545         rcu_register_thread();
 546         rcu_thread_online();
 547
 548         DBG("Entering work execution loop");
 549         pthread_mutex_lock(&executor->work.lock);
 550         while (!executor->should_quit) {
 551                 int ret;
 552                 struct action_work_item *work_item;
 553
 554                 health_code_update();
 555                 if (executor->work.pending_count == 0) {
 556                         health_poll_entry();
 557                         DBG("No work items enqueued, entering wait");
 558                         pthread_cond_wait(&executor->work.cond,
 559                                         &executor->work.lock);
 560                         DBG("Woke-up from wait");
 561                         health_poll_exit();
 562                         continue;
 563                 }
 564
 565                 /* Pop item from front of the list with work lock held. */
 566                 work_item = cds_list_first_entry(&executor->work.list,
 567                                 struct action_work_item, list_node);
 568                 cds_list_del(&work_item->list_node);
 569                 executor->work.pending_count--;
 570
 571                 /*
 572                  * Work can be performed without holding the work lock,
 573                  * allowing new items to be queued.
 574                  */
 575                 pthread_mutex_unlock(&executor->work.lock);
 576                 ret = action_work_item_execute(executor, work_item);
 577                 action_work_item_destroy(work_item);
 578                 if (ret) {
 579                         /* Fatal error. */
 580                         break;
 581                 }
 582
 583                 health_code_update();
 584                 pthread_mutex_lock(&executor->work.lock);
 585         }
 586
 587         if (executor->should_quit) {
 588                 pthread_mutex_unlock(&executor->work.lock);
 589         }
 590         DBG("Left work execution loop");
 591
 592         health_code_update();
 593
 594         rcu_thread_offline();
 595         rcu_unregister_thread();
 596         health_unregister(health_sessiond);
 597
 598         return NULL;
 599 }
 600
 601 static bool shutdown_action_executor_thread(void *_data)
 602 {
 603         struct action_executor *executor = _data;
 604
 605         pthread_mutex_lock(&executor->work.lock);
 606         executor->should_quit = true;
 607         pthread_cond_signal(&executor->work.cond);
 608         pthread_mutex_unlock(&executor->work.lock);
 609         return true;
 610 }
 611
 612 static void clean_up_action_executor_thread(void *_data)
 613 {
 614         struct action_executor *executor = _data;
 615
 616         assert(cds_list_empty(&executor->work.list));
 617
 618         pthread_mutex_destroy(&executor->work.lock);
 619         pthread_cond_destroy(&executor->work.cond);
 620         free(executor);
 621 }
 622
 623 struct action_executor *action_executor_create(
 624                 struct notification_thread_handle *handle)
 625 {
 626         struct action_executor *executor = zmalloc(sizeof(*executor));
 627
 628         if (!executor) {
 629                 goto end;
 630         }
 631
 632         CDS_INIT_LIST_HEAD(&executor->work.list);
 633         pthread_cond_init(&executor->work.cond, NULL);
 634         pthread_mutex_init(&executor->work.lock, NULL);
 635         executor->notification_thread_handle = handle;
 636
 637         executor->thread = lttng_thread_create(THREAD_NAME,
 638                         action_executor_thread, shutdown_action_executor_thread,
 639                         clean_up_action_executor_thread, executor);
 640 end:
 641         return executor;
 642 }
 643
 644 void action_executor_destroy(struct action_executor *executor)
 645 {
 646         struct action_work_item *work_item, *tmp;
 647
 648         /* TODO Wait for work list to drain? */
 649         lttng_thread_shutdown(executor->thread);
 650         pthread_mutex_lock(&executor->work.lock);
 651         if (executor->work.pending_count != 0) {
 652                 WARN("%" PRIu64
 653                         " trigger action%s still queued for execution and will be discarded",
 654                                 executor->work.pending_count,
 655                                 executor->work.pending_count == 1 ? " is" :
 656                                                                     "s are");
 657         }
 658
 659         cds_list_for_each_entry_safe (
 660                         work_item, tmp, &executor->work.list, list_node) {
 661                 WARN("Discarding action work item %" PRIu64
 662                                 " associated to trigger `%s`",
 663                                 work_item->id, get_trigger_name(work_item->trigger));
 664                 cds_list_del(&work_item->list_node);
 665                 action_work_item_destroy(work_item);
 666         }
 667         pthread_mutex_unlock(&executor->work.lock);
 668         lttng_thread_put(executor->thread);
 669 }
 670
 671 /* RCU read-lock must be held by the caller. */
 672 enum action_executor_status action_executor_enqueue(
 673                 struct action_executor *executor,
 674                 struct lttng_trigger *trigger,
 675                 struct lttng_evaluation *evaluation,
 676                 const struct lttng_credentials *object_creds,
 677                 struct notification_client_list *client_list)
 678 {
 679         enum action_executor_status executor_status = ACTION_EXECUTOR_STATUS_OK;
 680         const uint64_t work_item_id = executor->next_work_item_id++;
 681         struct action_work_item *work_item;
 682         bool signal = false;
 683
 684         pthread_mutex_lock(&executor->work.lock);
 685         /* Check for queue overflow. */
 686         if (executor->work.pending_count >= MAX_QUEUED_WORK_COUNT) {
 687                 /* Most likely spammy, remove if it is the case. */
 688                 DBG("Refusing to enqueue action for trigger `%s` as work item %" PRIu64
 689                         " (overflow)", get_trigger_name(trigger), work_item_id);
 690                 executor_status = ACTION_EXECUTOR_STATUS_OVERFLOW;
 691                 goto error_unlock;
 692         }
 693
 694         work_item = zmalloc(sizeof(*work_item));
 695         if (!work_item) {
 696                 PERROR("Failed to allocate action executor work item on behalf of trigger `%s`",
 697                                 get_trigger_name(trigger));
 698                 executor_status = ACTION_EXECUTOR_STATUS_ERROR;
 699                 goto error_unlock;
 700         }
 701
 702         lttng_trigger_get(trigger);
 703         if (client_list) {
 704                 const bool reference_acquired =
 705                                 notification_client_list_get(client_list);
 706
 707                 assert(reference_acquired);
 708         }
 709
 710         *work_item = (typeof(*work_item)){
 711                         .id = work_item_id,
 712                         .trigger = trigger,
 713                         /* Ownership transferred to the work item. */
 714                         .evaluation = evaluation,
 715                         .object_creds = {
 716                                 .is_set = !!object_creds,
 717                                 .value = object_creds ? *object_creds :
 718                                         (typeof(work_item->object_creds.value)) {},
 719                         },
 720                         .client_list = client_list,
 721                         .list_node = CDS_LIST_HEAD_INIT(work_item->list_node),
 722         };
 723
 724         evaluation = NULL;
 725         cds_list_add_tail(&work_item->list_node, &executor->work.list);
 726         executor->work.pending_count++;
 727         DBG("Enqueued action for trigger `%s` as work item #%" PRIu64,
 728                         get_trigger_name(trigger), work_item_id);
 729         signal = true;
 730
 731 error_unlock:
 732         if (signal) {
 733                 pthread_cond_signal(&executor->work.cond);
 734         }
 735         pthread_mutex_unlock(&executor->work.lock);
 736
 737         lttng_evaluation_destroy(evaluation);
 738         return executor_status;
 739 }