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  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License, version 2 only,
   7  * as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #define _LGPL_SOURCE
  20 #include <errno.h>
  21 #include <urcu/list.h>
  22 #include <string.h>
  23
  24 #include <lttng/lttng.h>
  25 #include <common/error.h>
  26 #include <common/sessiond-comm/sessiond-comm.h>
  27 #include <common/filter.h>
  28 #include <common/context.h>
  29
  30 #include "channel.h"
  31 #include "event.h"
  32 #include "kernel.h"
  33 #include "lttng-sessiond.h"
  34 #include "ust-ctl.h"
  35 #include "ust-app.h"
  36 #include "trace-kernel.h"
  37 #include "trace-ust.h"
  38 #include "agent.h"
  39
  40 /*
  41  * Add unique UST event based on the event name, filter bytecode and loglevel.
  42  */
  43 static void add_unique_ust_event(struct lttng_ht *ht,
  44                 struct ltt_ust_event *event)
  45 {
  46         struct cds_lfht_node *node_ptr;
  47         struct ltt_ust_ht_key key;
  48
  49         assert(ht);
  50         assert(ht->ht);
  51         assert(event);
  52
  53         key.name = event->attr.name;
  54         key.filter = (struct lttng_filter_bytecode *) event->filter;
  55         key.loglevel_type = event->attr.loglevel_type;
  56         key.loglevel_value = event->attr.loglevel;
  57         key.exclusion = event->exclusion;
  58
  59         node_ptr = cds_lfht_add_unique(ht->ht,
  60                         ht->hash_fct(event->node.key, lttng_ht_seed),
  61                         trace_ust_ht_match_event, &key, &event->node.node);
  62         assert(node_ptr == &event->node.node);
  63 }
  64
  65 /*
  66  * Disable kernel tracepoint events for a channel from the kernel session of
  67  * a specified event_name and event type.
  68  * On type LTTNG_EVENT_ALL all events with event_name are disabled.
  69  * If event_name is NULL all events of the specified type are disabled.
  70  */
  71 int event_kernel_disable_event(struct ltt_kernel_channel *kchan,
  72                 char *event_name, enum lttng_event_type type)
  73 {
  74         int ret, error = 0, found = 0;
  75         struct ltt_kernel_event *kevent;
  76
  77         assert(kchan);
  78
  79         /* For each event in the kernel session */
  80         cds_list_for_each_entry(kevent, &kchan->events_list.head, list) {
  81                 if (type != LTTNG_EVENT_ALL && kevent->type != type)
  82                         continue;
  83                 if (event_name != NULL && strcmp(event_name, kevent->event->name)) {
  84                         continue;
  85                 }
  86                 found++;
  87                 ret = kernel_disable_event(kevent);
  88                 if (ret < 0) {
  89                         error = 1;
  90                         continue;
  91                 }
  92         }
  93         DBG("Disable kernel event: found %d events with name: %s and type: %d",
  94                         found, event_name ? event_name : "NULL", type);
  95
  96         if (event_name != NULL && !found) {
  97                 ret = LTTNG_ERR_NO_EVENT;
  98         } else {
  99                 ret = error ? LTTNG_ERR_KERN_DISABLE_FAIL : LTTNG_OK;
 100         }
 101
 102         return ret;
 103 }
 104
 105 /*
 106  * Enable kernel tracepoint event for a channel from the kernel session.
 107  * We own filter_expression and filter.
 108  */
 109 int event_kernel_enable_event(struct ltt_kernel_channel *kchan,
 110                 struct lttng_event *event, char *filter_expression,
 111                 struct lttng_filter_bytecode *filter)
 112 {
 113         int ret;
 114         struct ltt_kernel_event *kevent;
 115
 116         assert(kchan);
 117         assert(event);
 118
 119         kevent = trace_kernel_find_event(event->name, kchan,
 120                         event->type, filter);
 121         if (kevent == NULL) {
 122                 ret = kernel_create_event(event, kchan, filter_expression, filter);
 123                 /* We have passed ownership */
 124                 filter_expression = NULL;
 125                 filter = NULL;
 126                 if (ret) {
 127                         goto end;
 128                 }
 129         } else if (kevent->enabled == 0) {
 130                 ret = kernel_enable_event(kevent);
 131                 if (ret < 0) {
 132                         ret = LTTNG_ERR_KERN_ENABLE_FAIL;
 133                         goto end;
 134                 }
 135         } else {
 136                 /* At this point, the event is considered enabled */
 137                 ret = LTTNG_ERR_KERN_EVENT_EXIST;
 138                 goto end;
 139         }
 140
 141         ret = LTTNG_OK;
 142 end:
 143         free(filter_expression);
 144         free(filter);
 145         return ret;
 146 }
 147
 148 /*
 149  * ============================
 150  * UST : The Ultimate Frontier!
 151  * ============================
 152  */
 153
 154 /*
 155  * Enable UST tracepoint event for a channel from a UST session.
 156  * We own filter_expression, filter, and exclusion.
 157  */
 158 int event_ust_enable_tracepoint(struct ltt_ust_session *usess,
 159                 struct ltt_ust_channel *uchan, struct lttng_event *event,
 160                 char *filter_expression,
 161                 struct lttng_filter_bytecode *filter,
 162                 struct lttng_event_exclusion *exclusion,
 163                 bool internal_event)
 164 {
 165         int ret = LTTNG_OK, to_create = 0;
 166         struct ltt_ust_event *uevent;
 167
 168         assert(usess);
 169         assert(uchan);
 170         assert(event);
 171
 172         rcu_read_lock();
 173
 174         uevent = trace_ust_find_event(uchan->events, event->name, filter,
 175                         event->loglevel_type, event->loglevel, exclusion);
 176         if (!uevent) {
 177                 ret = trace_ust_create_event(event, filter_expression,
 178                                 filter, exclusion, internal_event, &uevent);
 179                 /* We have passed ownership */
 180                 filter_expression = NULL;
 181                 filter = NULL;
 182                 exclusion = NULL;
 183                 if (ret != LTTNG_OK) {
 184                         goto error;
 185                 }
 186
 187                 /* Valid to set it after the goto error since uevent is still NULL */
 188                 to_create = 1;
 189         }
 190
 191         if (uevent->enabled) {
 192                 /* It's already enabled so everything is OK */
 193                 assert(!to_create);
 194                 ret = LTTNG_ERR_UST_EVENT_ENABLED;
 195                 goto end;
 196         }
 197
 198         uevent->enabled = 1;
 199         if (to_create) {
 200                 /* Add ltt ust event to channel */
 201                 add_unique_ust_event(uchan->events, uevent);
 202         }
 203
 204         if (!usess->active) {
 205                 goto end;
 206         }
 207
 208         if (to_create) {
 209                 /* Create event on all UST registered apps for session */
 210                 ret = ust_app_create_event_glb(usess, uchan, uevent);
 211         } else {
 212                 /* Enable event on all UST registered apps for session */
 213                 ret = ust_app_enable_event_glb(usess, uchan, uevent);
 214         }
 215
 216         if (ret < 0) {
 217                 if (ret == -LTTNG_UST_ERR_EXIST) {
 218                         ret = LTTNG_ERR_UST_EVENT_EXIST;
 219                         goto end;
 220                 } else {
 221                         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 222                         goto error;
 223                 }
 224         }
 225
 226         DBG("Event UST %s %s in channel %s", uevent->attr.name,
 227                         to_create ? "created" : "enabled", uchan->name);
 228
 229         ret = LTTNG_OK;
 230
 231 end:
 232         rcu_read_unlock();
 233         free(filter_expression);
 234         free(filter);
 235         free(exclusion);
 236         return ret;
 237
 238 error:
 239         /*
 240          * Only destroy event on creation time (not enabling time) because if the
 241          * event is found in the channel (to_create == 0), it means that at some
 242          * point the enable_event worked and it's thus valid to keep it alive.
 243          * Destroying it also implies that we also destroy it's shadow copy to sync
 244          * everyone up.
 245          */
 246         if (to_create) {
 247                 /* In this code path, the uevent was not added to the hash table */
 248                 trace_ust_destroy_event(uevent);
 249         }
 250         rcu_read_unlock();
 251         free(filter_expression);
 252         free(filter);
 253         free(exclusion);
 254         return ret;
 255 }
 256
 257 /*
 258  * Disable UST tracepoint of a channel from a UST session.
 259  */
 260 int event_ust_disable_tracepoint(struct ltt_ust_session *usess,
 261                 struct ltt_ust_channel *uchan, char *event_name)
 262 {
 263         int ret;
 264         struct ltt_ust_event *uevent;
 265         struct lttng_ht_node_str *node;
 266         struct lttng_ht_iter iter;
 267         struct lttng_ht *ht;
 268
 269         assert(usess);
 270         assert(uchan);
 271         assert(event_name);
 272
 273         ht = uchan->events;
 274
 275         rcu_read_lock();
 276
 277         /*
 278          * We use a custom lookup since we need the iterator for the next_duplicate
 279          * call in the do while loop below.
 280          */
 281         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) event_name, lttng_ht_seed),
 282                         trace_ust_ht_match_event_by_name, event_name, &iter.iter);
 283         node = lttng_ht_iter_get_node_str(&iter);
 284         if (node == NULL) {
 285                 DBG2("Trace UST event NOT found by name %s", event_name);
 286                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 287                 goto error;
 288         }
 289
 290         do {
 291                 uevent = caa_container_of(node, struct ltt_ust_event, node);
 292                 assert(uevent);
 293
 294                 if (uevent->enabled == 0) {
 295                         /* It's already disabled so everything is OK */
 296                         goto next;
 297                 }
 298                 uevent->enabled = 0;
 299                 DBG2("Event UST %s disabled in channel %s", uevent->attr.name,
 300                                 uchan->name);
 301
 302                 if (!usess->active) {
 303                         goto next;
 304                 }
 305                 ret = ust_app_disable_event_glb(usess, uchan, uevent);
 306                 if (ret < 0 && ret != -LTTNG_UST_ERR_EXIST) {
 307                         ret = LTTNG_ERR_UST_DISABLE_FAIL;
 308                         goto error;
 309                 }
 310 next:
 311                 /* Get next duplicate event by name. */
 312                 cds_lfht_next_duplicate(ht->ht, trace_ust_ht_match_event_by_name,
 313                                 event_name, &iter.iter);
 314                 node = lttng_ht_iter_get_node_str(&iter);
 315         } while (node);
 316
 317         ret = LTTNG_OK;
 318
 319 error:
 320         rcu_read_unlock();
 321         return ret;
 322 }
 323
 324 /*
 325  * Disable all UST tracepoints for a channel from a UST session.
 326  */
 327 int event_ust_disable_all_tracepoints(struct ltt_ust_session *usess,
 328                 struct ltt_ust_channel *uchan)
 329 {
 330         int ret, i, size, error = 0;
 331         struct lttng_ht_iter iter;
 332         struct ltt_ust_event *uevent = NULL;
 333         struct lttng_event *events = NULL;
 334
 335         assert(usess);
 336         assert(uchan);
 337
 338         rcu_read_lock();
 339
 340         /* Disabling existing events */
 341         cds_lfht_for_each_entry(uchan->events->ht, &iter.iter, uevent,
 342                         node.node) {
 343                 if (uevent->enabled == 1) {
 344                         ret = event_ust_disable_tracepoint(usess, uchan,
 345                                         uevent->attr.name);
 346                         if (ret < 0) {
 347                                 error = LTTNG_ERR_UST_DISABLE_FAIL;
 348                                 continue;
 349                         }
 350                 }
 351         }
 352
 353         /* Get all UST available events */
 354         size = ust_app_list_events(&events);
 355         if (size < 0) {
 356                 ret = LTTNG_ERR_UST_LIST_FAIL;
 357                 goto error;
 358         }
 359
 360         for (i = 0; i < size; i++) {
 361                 ret = event_ust_disable_tracepoint(usess, uchan,
 362                                 events[i].name);
 363                 if (ret < 0) {
 364                         /* Continue to disable the rest... */
 365                         error = LTTNG_ERR_UST_DISABLE_FAIL;
 366                         continue;
 367                 }
 368         }
 369
 370         ret = error ? error : LTTNG_OK;
 371 error:
 372         rcu_read_unlock();
 373         free(events);
 374         return ret;
 375 }
 376
 377 /*
 378  * Enable all agent event for a given UST session.
 379  *
 380  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 381  */
 382 int event_agent_enable_all(struct ltt_ust_session *usess,
 383                 struct agent *agt, struct lttng_event *event,
 384                 struct lttng_filter_bytecode *filter ,char *filter_expression)
 385 {
 386         int ret;
 387         struct agent_event *aevent;
 388         struct lttng_ht_iter iter;
 389
 390         assert(usess);
 391
 392         DBG("Event agent enabling ALL events for session %" PRIu64, usess->id);
 393
 394         /* Enable event on agent application through TCP socket. */
 395         ret = event_agent_enable(usess, agt, event, filter, filter_expression);
 396         if (ret != LTTNG_OK) {
 397                 goto error;
 398         }
 399
 400         /* Flag every event that they are now enabled. */
 401         rcu_read_lock();
 402         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, aevent,
 403                         node.node) {
 404                 aevent->enabled = 1;
 405         }
 406         rcu_read_unlock();
 407
 408         ret = LTTNG_OK;
 409
 410 error:
 411         return ret;
 412 }
 413
 414 /*
 415  * Check if this event's filter requires the activation of application contexts
 416  * and enable them in the agent.
 417  * TODO: bytecode iterator does not support non-legacy application
 418  * contexts yet. Not an issue for now, since they are not generated by
 419  * the lttng-ctl library.
 420  */
 421 static int add_filter_app_ctx(struct lttng_filter_bytecode *bytecode,
 422                 const char *filter_expression, struct agent *agt)
 423 {
 424         int ret = LTTNG_OK;
 425         char *provider_name = NULL, *ctx_name = NULL;
 426         struct bytecode_symbol_iterator *it =
 427                         bytecode_symbol_iterator_create(bytecode);
 428
 429         if (!it) {
 430                 ret = LTTNG_ERR_NOMEM;
 431                 goto end;
 432         }
 433
 434         do {
 435                 struct lttng_event_context ctx;
 436                 const char *symbol_name =
 437                                 bytecode_symbol_iterator_get_name(it);
 438
 439                 if (parse_application_context(symbol_name, &provider_name,
 440                                 &ctx_name)) {
 441                         /* Not an application context. */
 442                         continue;
 443                 }
 444
 445                 ctx.ctx = LTTNG_EVENT_CONTEXT_APP_CONTEXT;
 446                 ctx.u.app_ctx.provider_name = provider_name;
 447                 ctx.u.app_ctx.ctx_name = ctx_name;
 448
 449                 /* Recognized an application context. */
 450                 DBG("Enabling event with filter expression \"%s\" requires enabling the %s:%s application context.",
 451                                 filter_expression, provider_name, ctx_name);
 452
 453                 ret = agent_add_context(&ctx, agt);
 454                 if (ret != LTTNG_OK) {
 455                         ERR("Failed to add application context %s:%s.",
 456                                         provider_name, ctx_name);
 457                         goto end;
 458                 }
 459
 460                 ret = agent_enable_context(&ctx, agt->domain);
 461                 if (ret != LTTNG_OK) {
 462                         ERR("Failed to enable application context %s:%s.",
 463                                         provider_name, ctx_name);
 464                         goto end;
 465                 }
 466
 467                 free(provider_name);
 468                 free(ctx_name);
 469                 provider_name = ctx_name = NULL;
 470         } while (bytecode_symbol_iterator_next(it) == 0);
 471 end:
 472         free(provider_name);
 473         free(ctx_name);
 474         bytecode_symbol_iterator_destroy(it);
 475         return ret;
 476 }
 477
 478 /*
 479  * Enable a single agent event for a given UST session.
 480  *
 481  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 482  */
 483 int event_agent_enable(struct ltt_ust_session *usess,
 484                 struct agent *agt, struct lttng_event *event,
 485                 struct lttng_filter_bytecode *filter,
 486                 char *filter_expression)
 487 {
 488         int ret, created = 0;
 489         struct agent_event *aevent;
 490
 491         assert(usess);
 492         assert(event);
 493         assert(agt);
 494
 495         DBG("Event agent enabling %s for session %" PRIu64 " with loglevel type %d "
 496                         ", loglevel %d and filter \"%s\"", event->name,
 497                         usess->id, event->loglevel_type, event->loglevel,
 498                         filter_expression ? filter_expression : "NULL");
 499
 500         aevent = agent_find_event(event->name, event->loglevel_type,
 501                         event->loglevel, filter_expression, agt);
 502         if (!aevent) {
 503                 aevent = agent_create_event(event->name, event->loglevel_type,
 504                                 event->loglevel, filter,
 505                                 filter_expression);
 506                 if (!aevent) {
 507                         ret = LTTNG_ERR_NOMEM;
 508                         goto error;
 509                 }
 510                 filter = NULL;
 511                 filter_expression = NULL;
 512                 created = 1;
 513         }
 514
 515         if (created && filter) {
 516                 ret = add_filter_app_ctx(filter, filter_expression, agt);
 517                 if (ret != LTTNG_OK) {
 518                         goto error;
 519                 }
 520         }
 521
 522         /* Already enabled? */
 523         if (aevent->enabled) {
 524                 ret = LTTNG_OK;
 525                 goto end;
 526         }
 527
 528         ret = agent_enable_event(aevent, agt->domain);
 529         if (ret != LTTNG_OK) {
 530                 goto error;
 531         }
 532
 533         /* If the event was created prior to the enable, add it to the domain. */
 534         if (created) {
 535                 agent_add_event(aevent, agt);
 536         }
 537
 538         ret = LTTNG_OK;
 539         goto end;
 540
 541 error:
 542         if (created) {
 543                 agent_destroy_event(aevent);
 544         }
 545 end:
 546         free(filter);
 547         free(filter_expression);
 548         return ret;
 549 }
 550
 551 /*
 552  * Return the default event name associated with the provided UST domain. Return
 553  * NULL on error.
 554  */
 555 const char *event_get_default_agent_ust_name(enum lttng_domain_type domain)
 556 {
 557         const char *default_event_name = NULL;
 558
 559         switch (domain) {
 560         case LTTNG_DOMAIN_LOG4J:
 561                 default_event_name = DEFAULT_LOG4J_EVENT_NAME;
 562                 break;
 563         case LTTNG_DOMAIN_JUL:
 564                 default_event_name = DEFAULT_JUL_EVENT_NAME;
 565                 break;
 566         case LTTNG_DOMAIN_PYTHON:
 567                 default_event_name = DEFAULT_PYTHON_EVENT_NAME;
 568                 break;
 569         default:
 570                 assert(0);
 571         }
 572
 573         return default_event_name;
 574 }
 575
 576 /*
 577  * Disable a given agent event for a given UST session.
 578  *
 579  * Must be called with the RCU read lock held.
 580  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 581  */
 582 static int event_agent_disable_one(struct ltt_ust_session *usess,
 583                 struct agent *agt, struct agent_event *aevent)
 584 {
 585         int ret;
 586         struct ltt_ust_event *uevent = NULL;
 587         struct ltt_ust_channel *uchan = NULL;
 588         const char *ust_event_name, *ust_channel_name;
 589
 590         assert(agt);
 591         assert(usess);
 592         assert(aevent);
 593
 594         DBG("Event agent disabling %s (loglevel type %d, loglevel value %d) for session %" PRIu64,
 595                 aevent->name, aevent->loglevel_type, aevent->loglevel_value,
 596                 usess->id);
 597
 598         /* Already disabled? */
 599         if (!aevent->enabled) {
 600                 goto end;
 601         }
 602
 603         if (agt->domain == LTTNG_DOMAIN_JUL) {
 604                 ust_channel_name = DEFAULT_JUL_CHANNEL_NAME;
 605         } else if (agt->domain == LTTNG_DOMAIN_LOG4J) {
 606                 ust_channel_name = DEFAULT_LOG4J_CHANNEL_NAME;
 607         } else if (agt->domain == LTTNG_DOMAIN_PYTHON) {
 608                 ust_channel_name = DEFAULT_PYTHON_CHANNEL_NAME;
 609         } else {
 610                 ret = LTTNG_ERR_INVALID;
 611                 goto error;
 612         }
 613
 614         /*
 615          * Disable it on the UST side. First get the channel reference then find
 616          * the event and finally disable it.
 617          */
 618         uchan = trace_ust_find_channel_by_name(usess->domain_global.channels,
 619                         (char *) ust_channel_name);
 620         if (!uchan) {
 621                 ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
 622                 goto error;
 623         }
 624
 625         ust_event_name = event_get_default_agent_ust_name(agt->domain);
 626         if (!ust_event_name) {
 627                 ret = LTTNG_ERR_FATAL;
 628                 goto error;
 629         }
 630
 631         /*
 632          * Agent UST event has its loglevel type forced to
 633          * LTTNG_UST_LOGLEVEL_ALL. The actual loglevel type/value filtering
 634          * happens thanks to an UST filter. The following -1 is actually
 635          * ignored since the type is LTTNG_UST_LOGLEVEL_ALL.
 636          */
 637         uevent = trace_ust_find_event(uchan->events, (char *) ust_event_name,
 638                         aevent->filter, LTTNG_UST_LOGLEVEL_ALL, -1, NULL);
 639         /* If the agent event exists, it must be available on the UST side. */
 640         assert(uevent);
 641
 642         if (usess->active) {
 643                 ret = ust_app_disable_event_glb(usess, uchan, uevent);
 644                 if (ret < 0 && ret != -LTTNG_UST_ERR_EXIST) {
 645                         ret = LTTNG_ERR_UST_DISABLE_FAIL;
 646                         goto error;
 647                 }
 648         }
 649
 650         /*
 651          * Flag event that it's disabled so the shadow copy on the ust app side
 652          * will disable it if an application shows up.
 653          */
 654         uevent->enabled = 0;
 655
 656         ret = agent_disable_event(aevent, agt->domain);
 657         if (ret != LTTNG_OK) {
 658                 goto error;
 659         }
 660
 661 end:
 662         return LTTNG_OK;
 663
 664 error:
 665         return ret;
 666 }
 667
 668 /*
 669  * Disable all agent events matching a given name for a given UST session.
 670  *
 671  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 672  */
 673 int event_agent_disable(struct ltt_ust_session *usess, struct agent *agt,
 674                 char *event_name)
 675 {
 676         int ret = LTTNG_OK;
 677         struct agent_event *aevent;
 678         struct lttng_ht_iter iter;
 679         struct lttng_ht_node_str *node;
 680
 681         assert(agt);
 682         assert(usess);
 683         assert(event_name);
 684
 685         DBG("Event agent disabling %s (all loglevels) for session %" PRIu64, event_name, usess->id);
 686
 687         rcu_read_lock();
 688         agent_find_events_by_name(event_name, agt, &iter);
 689         node = lttng_ht_iter_get_node_str(&iter);
 690
 691         if (node == NULL) {
 692                 DBG2("Event agent NOT found by name %s", event_name);
 693                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 694                 goto end;
 695         }
 696
 697         do {
 698                 aevent = caa_container_of(node, struct agent_event, node);
 699                 ret = event_agent_disable_one(usess, agt, aevent);
 700
 701                 if (ret != LTTNG_OK) {
 702                         goto end;
 703                 }
 704
 705                 /* Get next duplicate agent event by name. */
 706                 agent_event_next_duplicate(event_name, agt, &iter);
 707                 node = lttng_ht_iter_get_node_str(&iter);
 708         } while (node);
 709 end:
 710         rcu_read_unlock();
 711         return ret;
 712 }
 713 /*
 714  * Disable all agent event for a given UST session.
 715  *
 716  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 717  */
 718 int event_agent_disable_all(struct ltt_ust_session *usess,
 719                 struct agent *agt)
 720 {
 721         int ret;
 722         struct agent_event *aevent;
 723         struct lttng_ht_iter iter;
 724
 725         assert(agt);
 726         assert(usess);
 727
 728         /*
 729          * Disable event on agent application. Continue to disable all other events
 730          * if the * event is not found.
 731          */
 732         ret = event_agent_disable(usess, agt, "*");
 733         if (ret != LTTNG_OK && ret != LTTNG_ERR_UST_EVENT_NOT_FOUND) {
 734                 goto error;
 735         }
 736
 737         /* Disable every event. */
 738         rcu_read_lock();
 739         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, aevent,
 740                         node.node) {
 741                 if (!aevent->enabled) {
 742                         continue;
 743                 }
 744
 745                 ret = event_agent_disable(usess, agt, aevent->name);
 746                 if (ret != LTTNG_OK) {
 747                         goto error_unlock;
 748                 }
 749         }
 750         ret = LTTNG_OK;
 751
 752 error_unlock:
 753         rcu_read_unlock();
 754 error:
 755         return ret;
 756 }