src/bin/lttng-sessiond/event.c

   1 /*
   2  * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
   3  * Copyright (C) 2016 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   4  *
   5  * SPDX-License-Identifier: GPL-2.0-only
   6  *
   7  */
   8
   9 #define _LGPL_SOURCE
  10 #include <errno.h>
  11 #include <urcu/list.h>
  12 #include <string.h>
  13
  14 #include <lttng/lttng.h>
  15 #include <lttng/condition/condition.h>
  16 #include <lttng/condition/event-rule.h>
  17 #include <lttng/event-rule/event-rule.h>
  18 #include <lttng/event-rule/event-rule-internal.h>
  19 #include <common/bytecode/bytecode.h>
  20 #include <common/error.h>
  21 #include <common/sessiond-comm/sessiond-comm.h>
  22 #include <common/filter.h>
  23 #include <common/context.h>
  24
  25 #include "channel.h"
  26 #include "event.h"
  27 #include "kernel.h"
  28 #include "lttng-sessiond.h"
  29 #include "lttng-ust-ctl.h"
  30 #include "lttng-ust-error.h"
  31 #include "ust-app.h"
  32 #include "trace-kernel.h"
  33 #include "trace-ust.h"
  34 #include "agent.h"
  35 #include "utils.h"
  36
  37 /*
  38  * Add unique UST event based on the event name, filter bytecode and loglevel.
  39  */
  40 static void add_unique_ust_event(struct lttng_ht *ht,
  41                 struct ltt_ust_event *event)
  42 {
  43         struct cds_lfht_node *node_ptr;
  44         struct ltt_ust_ht_key key;
  45
  46         assert(ht);
  47         assert(ht->ht);
  48         assert(event);
  49
  50         key.name = event->attr.name;
  51         key.filter = (struct lttng_bytecode *) event->filter;
  52         key.loglevel_type = event->attr.loglevel_type;
  53         key.loglevel_value = event->attr.loglevel;
  54         key.exclusion = event->exclusion;
  55
  56         node_ptr = cds_lfht_add_unique(ht->ht,
  57                         ht->hash_fct(event->node.key, lttng_ht_seed),
  58                         trace_ust_ht_match_event, &key, &event->node.node);
  59         assert(node_ptr == &event->node.node);
  60 }
  61
  62 /*
  63  * Disable kernel tracepoint events for a channel from the kernel session of
  64  * a specified event_name and event type.
  65  * On type LTTNG_EVENT_ALL all events with event_name are disabled.
  66  * If event_name is NULL all events of the specified type are disabled.
  67  */
  68 int event_kernel_disable_event(struct ltt_kernel_channel *kchan,
  69                 const char *event_name, enum lttng_event_type type)
  70 {
  71         int ret, error = 0, found = 0;
  72         struct ltt_kernel_event *kevent;
  73
  74         assert(kchan);
  75
  76         /* For each event in the kernel session */
  77         cds_list_for_each_entry(kevent, &kchan->events_list.head, list) {
  78                 if (type != LTTNG_EVENT_ALL && kevent->type != type)
  79                         continue;
  80                 if (event_name != NULL && strcmp(event_name, kevent->event->name)) {
  81                         continue;
  82                 }
  83                 found++;
  84                 ret = kernel_disable_event(kevent);
  85                 if (ret < 0) {
  86                         error = 1;
  87                         continue;
  88                 }
  89         }
  90         DBG("Disable kernel event: found %d events with name: %s and type: %d",
  91                         found, event_name ? event_name : "NULL", type);
  92
  93         if (event_name != NULL && !found) {
  94                 ret = LTTNG_ERR_NO_EVENT;
  95         } else {
  96                 ret = error ? LTTNG_ERR_KERN_DISABLE_FAIL : LTTNG_OK;
  97         }
  98
  99         return ret;
 100 }
 101
 102 /*
 103  * Enable kernel tracepoint event for a channel from the kernel session.
 104  * We own filter_expression and filter.
 105  */
 106 int event_kernel_enable_event(struct ltt_kernel_channel *kchan,
 107                 struct lttng_event *event, char *filter_expression,
 108                 struct lttng_bytecode *filter)
 109 {
 110         int ret;
 111         struct ltt_kernel_event *kevent;
 112
 113         assert(kchan);
 114         assert(event);
 115
 116         kevent = trace_kernel_find_event(event->name, kchan,
 117                         event->type, filter);
 118         if (kevent == NULL) {
 119                 ret = kernel_create_event(event, kchan, filter_expression, filter);
 120                 /* We have passed ownership */
 121                 filter_expression = NULL;
 122                 filter = NULL;
 123                 if (ret) {
 124                         goto end;
 125                 }
 126         } else if (kevent->enabled == 0) {
 127                 ret = kernel_enable_event(kevent);
 128                 if (ret < 0) {
 129                         ret = LTTNG_ERR_KERN_ENABLE_FAIL;
 130                         goto end;
 131                 }
 132         } else {
 133                 /* At this point, the event is considered enabled */
 134                 ret = LTTNG_ERR_KERN_EVENT_EXIST;
 135                 goto end;
 136         }
 137
 138         ret = LTTNG_OK;
 139 end:
 140         free(filter_expression);
 141         free(filter);
 142         return ret;
 143 }
 144
 145 /*
 146  * ============================
 147  * UST : The Ultimate Frontier!
 148  * ============================
 149  */
 150
 151 /*
 152  * Enable UST tracepoint event for a channel from a UST session.
 153  * We own filter_expression, filter, and exclusion.
 154  */
 155 int event_ust_enable_tracepoint(struct ltt_ust_session *usess,
 156                 struct ltt_ust_channel *uchan, struct lttng_event *event,
 157                 char *filter_expression,
 158                 struct lttng_bytecode *filter,
 159                 struct lttng_event_exclusion *exclusion,
 160                 bool internal_event)
 161 {
 162         int ret = LTTNG_OK, to_create = 0;
 163         struct ltt_ust_event *uevent;
 164
 165         assert(usess);
 166         assert(uchan);
 167         assert(event);
 168
 169         rcu_read_lock();
 170
 171         uevent = trace_ust_find_event(uchan->events, event->name, filter,
 172                         (enum lttng_ust_loglevel_type) event->loglevel_type,
 173                         event->loglevel, exclusion);
 174         if (!uevent) {
 175                 ret = trace_ust_create_event(event, filter_expression,
 176                                 filter, exclusion, internal_event, &uevent);
 177                 /* We have passed ownership */
 178                 filter_expression = NULL;
 179                 filter = NULL;
 180                 exclusion = NULL;
 181                 if (ret != LTTNG_OK) {
 182                         goto error;
 183                 }
 184
 185                 /* Valid to set it after the goto error since uevent is still NULL */
 186                 to_create = 1;
 187         }
 188
 189         if (uevent->enabled) {
 190                 /* It's already enabled so everything is OK */
 191                 assert(!to_create);
 192                 ret = LTTNG_ERR_UST_EVENT_ENABLED;
 193                 goto end;
 194         }
 195
 196         uevent->enabled = 1;
 197         if (to_create) {
 198                 /* Add ltt ust event to channel */
 199                 add_unique_ust_event(uchan->events, uevent);
 200         }
 201
 202         if (!usess->active) {
 203                 goto end;
 204         }
 205
 206         if (to_create) {
 207                 /* Create event on all UST registered apps for session */
 208                 ret = ust_app_create_event_glb(usess, uchan, uevent);
 209         } else {
 210                 /* Enable event on all UST registered apps for session */
 211                 ret = ust_app_enable_event_glb(usess, uchan, uevent);
 212         }
 213
 214         if (ret < 0) {
 215                 if (ret == -LTTNG_UST_ERR_EXIST) {
 216                         ret = LTTNG_ERR_UST_EVENT_EXIST;
 217                         goto end;
 218                 } else {
 219                         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 220                         goto error;
 221                 }
 222         }
 223
 224         DBG("Event UST %s %s in channel %s", uevent->attr.name,
 225                         to_create ? "created" : "enabled", uchan->name);
 226
 227         ret = LTTNG_OK;
 228
 229 end:
 230         rcu_read_unlock();
 231         free(filter_expression);
 232         free(filter);
 233         free(exclusion);
 234         return ret;
 235
 236 error:
 237         /*
 238          * Only destroy event on creation time (not enabling time) because if the
 239          * event is found in the channel (to_create == 0), it means that at some
 240          * point the enable_event worked and it's thus valid to keep it alive.
 241          * Destroying it also implies that we also destroy it's shadow copy to sync
 242          * everyone up.
 243          */
 244         if (to_create) {
 245                 /* In this code path, the uevent was not added to the hash table */
 246                 trace_ust_destroy_event(uevent);
 247         }
 248         rcu_read_unlock();
 249         free(filter_expression);
 250         free(filter);
 251         free(exclusion);
 252         return ret;
 253 }
 254
 255 /*
 256  * Disable UST tracepoint of a channel from a UST session.
 257  */
 258 int event_ust_disable_tracepoint(struct ltt_ust_session *usess,
 259                 struct ltt_ust_channel *uchan, const char *event_name)
 260 {
 261         int ret;
 262         struct ltt_ust_event *uevent;
 263         struct lttng_ht_node_str *node;
 264         struct lttng_ht_iter iter;
 265         struct lttng_ht *ht;
 266
 267         assert(usess);
 268         assert(uchan);
 269         assert(event_name);
 270
 271         ht = uchan->events;
 272
 273         rcu_read_lock();
 274
 275         /*
 276          * We use a custom lookup since we need the iterator for the next_duplicate
 277          * call in the do while loop below.
 278          */
 279         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) event_name, lttng_ht_seed),
 280                         trace_ust_ht_match_event_by_name, event_name, &iter.iter);
 281         node = lttng_ht_iter_get_node_str(&iter);
 282         if (node == NULL) {
 283                 DBG2("Trace UST event NOT found by name %s", event_name);
 284                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 285                 goto error;
 286         }
 287
 288         do {
 289                 uevent = caa_container_of(node, struct ltt_ust_event, node);
 290                 assert(uevent);
 291
 292                 if (uevent->enabled == 0) {
 293                         /* It's already disabled so everything is OK */
 294                         goto next;
 295                 }
 296                 uevent->enabled = 0;
 297                 DBG2("Event UST %s disabled in channel %s", uevent->attr.name,
 298                                 uchan->name);
 299
 300                 if (!usess->active) {
 301                         goto next;
 302                 }
 303                 ret = ust_app_disable_event_glb(usess, uchan, uevent);
 304                 if (ret < 0 && ret != -LTTNG_UST_ERR_EXIST) {
 305                         ret = LTTNG_ERR_UST_DISABLE_FAIL;
 306                         goto error;
 307                 }
 308 next:
 309                 /* Get next duplicate event by name. */
 310                 cds_lfht_next_duplicate(ht->ht, trace_ust_ht_match_event_by_name,
 311                                 event_name, &iter.iter);
 312                 node = lttng_ht_iter_get_node_str(&iter);
 313         } while (node);
 314
 315         ret = LTTNG_OK;
 316
 317 error:
 318         rcu_read_unlock();
 319         return ret;
 320 }
 321
 322 /*
 323  * Disable all UST tracepoints for a channel from a UST session.
 324  */
 325 int event_ust_disable_all_tracepoints(struct ltt_ust_session *usess,
 326                 struct ltt_ust_channel *uchan)
 327 {
 328         int ret, i, size, error = 0;
 329         struct lttng_ht_iter iter;
 330         struct ltt_ust_event *uevent = NULL;
 331         struct lttng_event *events = NULL;
 332
 333         assert(usess);
 334         assert(uchan);
 335
 336         rcu_read_lock();
 337
 338         /* Disabling existing events */
 339         cds_lfht_for_each_entry(uchan->events->ht, &iter.iter, uevent,
 340                         node.node) {
 341                 if (uevent->enabled == 1) {
 342                         ret = event_ust_disable_tracepoint(usess, uchan,
 343                                         uevent->attr.name);
 344                         if (ret < 0) {
 345                                 error = LTTNG_ERR_UST_DISABLE_FAIL;
 346                                 continue;
 347                         }
 348                 }
 349         }
 350
 351         /* Get all UST available events */
 352         size = ust_app_list_events(&events);
 353         if (size < 0) {
 354                 ret = LTTNG_ERR_UST_LIST_FAIL;
 355                 goto error;
 356         }
 357
 358         for (i = 0; i < size; i++) {
 359                 ret = event_ust_disable_tracepoint(usess, uchan,
 360                                 events[i].name);
 361                 if (ret < 0) {
 362                         /* Continue to disable the rest... */
 363                         error = LTTNG_ERR_UST_DISABLE_FAIL;
 364                         continue;
 365                 }
 366         }
 367
 368         ret = error ? error : LTTNG_OK;
 369 error:
 370         rcu_read_unlock();
 371         free(events);
 372         return ret;
 373 }
 374
 375 static void agent_enable_all(struct agent *agt)
 376 {
 377         struct agent_event *aevent;
 378         struct lttng_ht_iter iter;
 379
 380         /* Flag every event that they are now enabled. */
 381         rcu_read_lock();
 382         cds_lfht_for_each_entry (
 383                         agt->events->ht, &iter.iter, aevent, node.node) {
 384                 aevent->enabled = 1;
 385         }
 386         rcu_read_unlock();
 387 }
 388
 389 /*
 390  * Enable all agent event for a given UST session.
 391  *
 392  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 393  */
 394 int event_agent_enable_all(struct ltt_ust_session *usess,
 395                 struct agent *agt, struct lttng_event *event,
 396                 struct lttng_bytecode *filter ,char *filter_expression)
 397 {
 398         int ret;
 399
 400         assert(usess);
 401
 402         DBG("Event agent enabling ALL events for session %" PRIu64, usess->id);
 403
 404         /* Enable event on agent application through TCP socket. */
 405         ret = event_agent_enable(usess, agt, event, filter, filter_expression);
 406         if (ret != LTTNG_OK) {
 407                 goto error;
 408         }
 409
 410         agent_enable_all(agt);
 411
 412         ret = LTTNG_OK;
 413
 414 error:
 415         return ret;
 416 }
 417
 418 /*
 419  * Check if this event's filter requires the activation of application contexts
 420  * and enable them in the agent.
 421  * TODO: bytecode iterator does not support non-legacy application
 422  * contexts yet. Not an issue for now, since they are not generated by
 423  * the lttng-ctl library.
 424  */
 425 static int add_filter_app_ctx(struct lttng_bytecode *bytecode,
 426                 const char *filter_expression, struct agent *agt)
 427 {
 428         int ret = LTTNG_OK;
 429         char *provider_name = NULL, *ctx_name = NULL;
 430         struct bytecode_symbol_iterator *it =
 431                         bytecode_symbol_iterator_create(bytecode);
 432
 433         if (!it) {
 434                 ret = LTTNG_ERR_NOMEM;
 435                 goto end;
 436         }
 437
 438         do {
 439                 struct lttng_event_context ctx;
 440                 const char *symbol_name =
 441                                 bytecode_symbol_iterator_get_name(it);
 442
 443                 if (parse_application_context(symbol_name, &provider_name,
 444                                 &ctx_name)) {
 445                         /* Not an application context. */
 446                         continue;
 447                 }
 448
 449                 ctx.ctx = LTTNG_EVENT_CONTEXT_APP_CONTEXT;
 450                 ctx.u.app_ctx.provider_name = provider_name;
 451                 ctx.u.app_ctx.ctx_name = ctx_name;
 452
 453                 /* Recognized an application context. */
 454                 DBG("Enabling event with filter expression \"%s\" requires enabling the %s:%s application context.",
 455                                 filter_expression, provider_name, ctx_name);
 456
 457                 ret = agent_add_context(&ctx, agt);
 458                 if (ret != LTTNG_OK) {
 459                         ERR("Failed to add application context %s:%s.",
 460                                         provider_name, ctx_name);
 461                         goto end;
 462                 }
 463
 464                 ret = agent_enable_context(&ctx, agt->domain);
 465                 if (ret != LTTNG_OK) {
 466                         ERR("Failed to enable application context %s:%s.",
 467                                         provider_name, ctx_name);
 468                         goto end;
 469                 }
 470
 471                 free(provider_name);
 472                 free(ctx_name);
 473                 provider_name = ctx_name = NULL;
 474         } while (bytecode_symbol_iterator_next(it) == 0);
 475 end:
 476         free(provider_name);
 477         free(ctx_name);
 478         bytecode_symbol_iterator_destroy(it);
 479         return ret;
 480 }
 481
 482 static int agent_enable(struct agent *agt,
 483                 struct lttng_event *event,
 484                 struct lttng_bytecode *filter,
 485                 char *filter_expression)
 486 {
 487         int ret, created = 0;
 488         struct agent_event *aevent;
 489
 490         assert(event);
 491         assert(agt);
 492
 493         aevent = agent_find_event(event->name, event->loglevel_type,
 494                         event->loglevel, filter_expression, agt);
 495         if (!aevent) {
 496                 aevent = agent_create_event(event->name, event->loglevel_type,
 497                                 event->loglevel, filter,
 498                                 filter_expression);
 499                 if (!aevent) {
 500                         ret = LTTNG_ERR_NOMEM;
 501                         goto error;
 502                 }
 503                 filter = NULL;
 504                 filter_expression = NULL;
 505                 created = 1;
 506                 assert(!aevent->enabled);
 507         }
 508
 509         if (created && aevent->filter) {
 510                 ret = add_filter_app_ctx(
 511                                 aevent->filter, aevent->filter_expression, agt);
 512                 if (ret != LTTNG_OK) {
 513                         goto error;
 514                 }
 515         }
 516
 517         /* Already enabled? */
 518         if (aevent->enabled) {
 519                 ret = LTTNG_OK;
 520                 goto end;
 521         }
 522
 523         ret = agent_enable_event(aevent, agt->domain);
 524         if (ret != LTTNG_OK) {
 525                 goto error;
 526         }
 527
 528         /* If the event was created prior to the enable, add it to the domain. */
 529         if (created) {
 530                 agent_add_event(aevent, agt);
 531         }
 532
 533         ret = LTTNG_OK;
 534         goto end;
 535
 536 error:
 537         if (created) {
 538                 agent_destroy_event(aevent);
 539         }
 540 end:
 541         free(filter);
 542         free(filter_expression);
 543         return ret;
 544 }
 545
 546 /*
 547  * Enable a single agent event for a given UST session.
 548  *
 549  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 550  */
 551 int event_agent_enable(struct ltt_ust_session *usess,
 552                 struct agent *agt,
 553                 struct lttng_event *event,
 554                 struct lttng_bytecode *filter,
 555                 char *filter_expression)
 556 {
 557         assert(usess);
 558         assert(event);
 559         assert(agt);
 560
 561         DBG("Event agent enabling %s for session %" PRIu64
 562             " with loglevel type %d "
 563             ", loglevel %d and filter \"%s\"",
 564                         event->name, usess->id, event->loglevel_type,
 565                         event->loglevel,
 566                         filter_expression ? filter_expression : "NULL");
 567
 568         return agent_enable(agt, event, filter, filter_expression);
 569 }
 570
 571 /*
 572  * Enable a single agent event for a trigger.
 573  *
 574  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 575  */
 576 int trigger_agent_enable(const struct lttng_trigger *trigger, struct agent *agt)
 577 {
 578         int ret;
 579         enum lttng_condition_status c_status;
 580         enum lttng_domain_type d_type;
 581         const struct lttng_condition *condition;
 582         const struct lttng_event_rule *rule;
 583         const char *filter_expression;
 584         char *filter_expression_copy = NULL;
 585         const struct lttng_bytecode *filter_bytecode;
 586         struct lttng_bytecode *filter_bytecode_copy = NULL;
 587         struct lttng_event *event = NULL;
 588
 589         assert(trigger);
 590         assert(agt);
 591
 592         condition = lttng_trigger_get_const_condition(trigger);
 593
 594         assert(lttng_condition_get_type(condition) ==
 595                         LTTNG_CONDITION_TYPE_EVENT_RULE_HIT);
 596
 597         c_status = lttng_condition_event_rule_get_rule(condition, &rule);
 598         assert(c_status == LTTNG_CONDITION_STATUS_OK);
 599
 600         assert(lttng_event_rule_get_type(rule) ==
 601                         LTTNG_EVENT_RULE_TYPE_TRACEPOINT);
 602
 603         d_type = lttng_event_rule_get_domain_type(rule);
 604         assert(d_type == agt->domain);
 605
 606         event = lttng_event_rule_generate_lttng_event(rule);
 607         if (!event) {
 608                 ret = LTTNG_ERR_NOMEM;
 609                 goto end;
 610         }
 611
 612         /* Get the internal filter_expression and bytecode */
 613         filter_expression = lttng_event_rule_get_filter(rule);
 614         if (filter_expression) {
 615                 filter_expression_copy = strdup(filter_expression);
 616                 if (!filter_expression_copy) {
 617                         ret = LTTNG_ERR_NOMEM;
 618                         goto end;
 619                 }
 620
 621                 /* Get the filter bytecode */
 622                 filter_bytecode = lttng_event_rule_get_filter_bytecode(rule);
 623                 if (filter_bytecode) {
 624                         filter_bytecode_copy = bytecode_copy (filter_bytecode);
 625                         if (!filter_bytecode_copy) {
 626                                 ret = LTTNG_ERR_NOMEM;
 627                                 goto end;
 628                         }
 629                 }
 630         }
 631
 632         DBG("Event agent enabling %s for trigger %" PRIu64
 633             " with loglevel type %d "
 634             ", loglevel %d and filter \"%s\"",
 635                         event->name, lttng_trigger_get_tracer_token(trigger),
 636                         event->loglevel_type, event->loglevel,
 637                         filter_expression ? filter_expression : "NULL");
 638
 639         ret = agent_enable(agt, event, filter_bytecode_copy,
 640                         filter_expression_copy);
 641         /* Ownership was passed even in case of error */
 642         filter_expression_copy = NULL;
 643         filter_bytecode_copy = NULL;
 644
 645 end:
 646         free(filter_expression_copy);
 647         free(filter_bytecode_copy);
 648         free(event);
 649         return ret;
 650 }
 651
 652 /*
 653  * Return the default event name associated with the provided UST domain. Return
 654  * NULL on error.
 655  */
 656 const char *event_get_default_agent_ust_name(enum lttng_domain_type domain)
 657 {
 658         const char *default_event_name = NULL;
 659
 660         switch (domain) {
 661         case LTTNG_DOMAIN_LOG4J:
 662                 default_event_name = DEFAULT_LOG4J_EVENT_NAME;
 663                 break;
 664         case LTTNG_DOMAIN_JUL:
 665                 default_event_name = DEFAULT_JUL_EVENT_NAME;
 666                 break;
 667         case LTTNG_DOMAIN_PYTHON:
 668                 default_event_name = DEFAULT_PYTHON_EVENT_NAME;
 669                 break;
 670         default:
 671                 assert(0);
 672         }
 673
 674         return default_event_name;
 675 }
 676
 677 static int trigger_agent_disable_one(const struct lttng_trigger *trigger,
 678                 struct agent *agt,
 679                 struct agent_event *aevent)
 680
 681 {
 682         int ret;
 683
 684         assert(agt);
 685         assert(trigger);
 686         assert(aevent);
 687
 688         /*
 689          * Actual ust event un-registration happens on the trigger
 690          * un-registration at that point.
 691          */
 692
 693         DBG("Event agent disabling %s (loglevel type %d, loglevel value %d) for trigger %" PRIu64,
 694                         aevent->name, aevent->loglevel_type,
 695                         aevent->loglevel_value, lttng_trigger_get_tracer_token(trigger));
 696
 697         /* Already disabled? */
 698         if (!aevent->enabled) {
 699                 goto end;
 700         }
 701
 702         ret = agent_disable_event(aevent, agt->domain);
 703         if (ret != LTTNG_OK) {
 704                 goto error;
 705         }
 706
 707 end:
 708         return LTTNG_OK;
 709
 710 error:
 711         return ret;
 712 }
 713
 714 /*
 715  * Disable a given agent event for a given UST session.
 716  *
 717  * Must be called with the RCU read lock held.
 718  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 719  */
 720 static int event_agent_disable_one(struct ltt_ust_session *usess,
 721                 struct agent *agt, struct agent_event *aevent)
 722 {
 723         int ret;
 724         struct ltt_ust_event *uevent = NULL;
 725         struct ltt_ust_channel *uchan = NULL;
 726         const char *ust_event_name, *ust_channel_name;
 727
 728         assert(agt);
 729         assert(usess);
 730         assert(aevent);
 731
 732         DBG("Event agent disabling %s (loglevel type %d, loglevel value %d) for session %" PRIu64,
 733                 aevent->name, aevent->loglevel_type, aevent->loglevel_value,
 734                 usess->id);
 735
 736         /* Already disabled? */
 737         if (!aevent->enabled) {
 738                 goto end;
 739         }
 740
 741         if (agt->domain == LTTNG_DOMAIN_JUL) {
 742                 ust_channel_name = DEFAULT_JUL_CHANNEL_NAME;
 743         } else if (agt->domain == LTTNG_DOMAIN_LOG4J) {
 744                 ust_channel_name = DEFAULT_LOG4J_CHANNEL_NAME;
 745         } else if (agt->domain == LTTNG_DOMAIN_PYTHON) {
 746                 ust_channel_name = DEFAULT_PYTHON_CHANNEL_NAME;
 747         } else {
 748                 ret = LTTNG_ERR_INVALID;
 749                 goto error;
 750         }
 751
 752         /*
 753          * Disable it on the UST side. First get the channel reference then find
 754          * the event and finally disable it.
 755          */
 756         uchan = trace_ust_find_channel_by_name(usess->domain_global.channels,
 757                         (char *) ust_channel_name);
 758         if (!uchan) {
 759                 ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
 760                 goto error;
 761         }
 762
 763         ust_event_name = event_get_default_agent_ust_name(agt->domain);
 764         if (!ust_event_name) {
 765                 ret = LTTNG_ERR_FATAL;
 766                 goto error;
 767         }
 768
 769         /*
 770          * Agent UST event has its loglevel type forced to
 771          * LTTNG_UST_LOGLEVEL_ALL. The actual loglevel type/value filtering
 772          * happens thanks to an UST filter. The following -1 is actually
 773          * ignored since the type is LTTNG_UST_LOGLEVEL_ALL.
 774          */
 775         uevent = trace_ust_find_event(uchan->events, (char *) ust_event_name,
 776                         aevent->filter, LTTNG_UST_LOGLEVEL_ALL, -1, NULL);
 777         /* If the agent event exists, it must be available on the UST side. */
 778         assert(uevent);
 779
 780         if (usess->active) {
 781                 ret = ust_app_disable_event_glb(usess, uchan, uevent);
 782                 if (ret < 0 && ret != -LTTNG_UST_ERR_EXIST) {
 783                         ret = LTTNG_ERR_UST_DISABLE_FAIL;
 784                         goto error;
 785                 }
 786         }
 787
 788         /*
 789          * Flag event that it's disabled so the shadow copy on the ust app side
 790          * will disable it if an application shows up.
 791          */
 792         uevent->enabled = 0;
 793
 794         ret = agent_disable_event(aevent, agt->domain);
 795         if (ret != LTTNG_OK) {
 796                 goto error;
 797         }
 798
 799 end:
 800         return LTTNG_OK;
 801
 802 error:
 803         return ret;
 804 }
 805
 806 /*
 807  * Disable agent event matching a given trigger.
 808  *
 809  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 810  */
 811 int trigger_agent_disable(
 812                 const struct lttng_trigger *trigger, struct agent *agt)
 813 {
 814         int ret = LTTNG_OK;
 815         struct agent_event *aevent;
 816
 817         assert(trigger);
 818         assert(agt);
 819
 820         DBG("Event agent disabling for trigger %" PRIu64,
 821                         lttng_trigger_get_tracer_token(trigger));
 822
 823         rcu_read_lock();
 824         aevent = agent_find_event_by_trigger(trigger, agt);
 825
 826         if (aevent == NULL) {
 827                 DBG2("Event agent NOT found by trigger %" PRIu64,
 828                                 lttng_trigger_get_tracer_token(trigger));
 829                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 830                 goto end;
 831         }
 832
 833         ret = trigger_agent_disable_one(trigger, agt, aevent);
 834
 835         if (ret != LTTNG_OK) {
 836                 goto end;
 837         }
 838
 839 end:
 840         rcu_read_unlock();
 841         return ret;
 842 }
 843
 844 /*
 845  * Disable all agent events matching a given name for a given UST session.
 846  *
 847  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 848  */
 849 int event_agent_disable(struct ltt_ust_session *usess, struct agent *agt,
 850                 const char *event_name)
 851 {
 852         int ret = LTTNG_OK;
 853         struct agent_event *aevent;
 854         struct lttng_ht_iter iter;
 855         struct lttng_ht_node_str *node;
 856
 857         assert(agt);
 858         assert(usess);
 859         assert(event_name);
 860
 861         DBG("Event agent disabling %s (all loglevels) for session %" PRIu64, event_name, usess->id);
 862
 863         rcu_read_lock();
 864         agent_find_events_by_name(event_name, agt, &iter);
 865         node = lttng_ht_iter_get_node_str(&iter);
 866
 867         if (node == NULL) {
 868                 DBG2("Event agent NOT found by name %s", event_name);
 869                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 870                 goto end;
 871         }
 872
 873         do {
 874                 aevent = caa_container_of(node, struct agent_event, node);
 875                 ret = event_agent_disable_one(usess, agt, aevent);
 876
 877                 if (ret != LTTNG_OK) {
 878                         goto end;
 879                 }
 880
 881                 /* Get next duplicate agent event by name. */
 882                 agent_event_next_duplicate(event_name, agt, &iter);
 883                 node = lttng_ht_iter_get_node_str(&iter);
 884         } while (node);
 885 end:
 886         rcu_read_unlock();
 887         return ret;
 888 }
 889 /*
 890  * Disable all agent event for a given UST session.
 891  *
 892  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 893  */
 894 int event_agent_disable_all(struct ltt_ust_session *usess,
 895                 struct agent *agt)
 896 {
 897         int ret;
 898         struct agent_event *aevent;
 899         struct lttng_ht_iter iter;
 900
 901         assert(agt);
 902         assert(usess);
 903
 904         /*
 905          * Disable event on agent application. Continue to disable all other events
 906          * if the * event is not found.
 907          */
 908         ret = event_agent_disable(usess, agt, "*");
 909         if (ret != LTTNG_OK && ret != LTTNG_ERR_UST_EVENT_NOT_FOUND) {
 910                 goto error;
 911         }
 912
 913         /* Disable every event. */
 914         rcu_read_lock();
 915         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, aevent,
 916                         node.node) {
 917                 if (!aevent->enabled) {
 918                         continue;
 919                 }
 920
 921                 ret = event_agent_disable(usess, agt, aevent->name);
 922                 if (ret != LTTNG_OK) {
 923                         goto error_unlock;
 924                 }
 925         }
 926         ret = LTTNG_OK;
 927
 928 error_unlock:
 929         rcu_read_unlock();
 930 error:
 931         return ret;
 932 }