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