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                 const 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                         (enum lttng_ust_loglevel_type) event->loglevel_type,
 176                         event->loglevel, exclusion);
 177         if (!uevent) {
 178                 ret = trace_ust_create_event(event, filter_expression,
 179                                 filter, exclusion, internal_event, &uevent);
 180                 /* We have passed ownership */
 181                 filter_expression = NULL;
 182                 filter = NULL;
 183                 exclusion = NULL;
 184                 if (ret != LTTNG_OK) {
 185                         goto error;
 186                 }
 187
 188                 /* Valid to set it after the goto error since uevent is still NULL */
 189                 to_create = 1;
 190         }
 191
 192         if (uevent->enabled) {
 193                 /* It's already enabled so everything is OK */
 194                 assert(!to_create);
 195                 ret = LTTNG_ERR_UST_EVENT_ENABLED;
 196                 goto end;
 197         }
 198
 199         uevent->enabled = 1;
 200         if (to_create) {
 201                 /* Add ltt ust event to channel */
 202                 add_unique_ust_event(uchan->events, uevent);
 203         }
 204
 205         if (!usess->active) {
 206                 goto end;
 207         }
 208
 209         if (to_create) {
 210                 /* Create event on all UST registered apps for session */
 211                 ret = ust_app_create_event_glb(usess, uchan, uevent);
 212         } else {
 213                 /* Enable event on all UST registered apps for session */
 214                 ret = ust_app_enable_event_glb(usess, uchan, uevent);
 215         }
 216
 217         if (ret < 0) {
 218                 if (ret == -LTTNG_UST_ERR_EXIST) {
 219                         ret = LTTNG_ERR_UST_EVENT_EXIST;
 220                         goto end;
 221                 } else {
 222                         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 223                         goto error;
 224                 }
 225         }
 226
 227         DBG("Event UST %s %s in channel %s", uevent->attr.name,
 228                         to_create ? "created" : "enabled", uchan->name);
 229
 230         ret = LTTNG_OK;
 231
 232 end:
 233         rcu_read_unlock();
 234         free(filter_expression);
 235         free(filter);
 236         free(exclusion);
 237         return ret;
 238
 239 error:
 240         /*
 241          * Only destroy event on creation time (not enabling time) because if the
 242          * event is found in the channel (to_create == 0), it means that at some
 243          * point the enable_event worked and it's thus valid to keep it alive.
 244          * Destroying it also implies that we also destroy it's shadow copy to sync
 245          * everyone up.
 246          */
 247         if (to_create) {
 248                 /* In this code path, the uevent was not added to the hash table */
 249                 trace_ust_destroy_event(uevent);
 250         }
 251         rcu_read_unlock();
 252         free(filter_expression);
 253         free(filter);
 254         free(exclusion);
 255         return ret;
 256 }
 257
 258 /*
 259  * Disable UST tracepoint of a channel from a UST session.
 260  */
 261 int event_ust_disable_tracepoint(struct ltt_ust_session *usess,
 262                 struct ltt_ust_channel *uchan, const char *event_name)
 263 {
 264         int ret;
 265         struct ltt_ust_event *uevent;
 266         struct lttng_ht_node_str *node;
 267         struct lttng_ht_iter iter;
 268         struct lttng_ht *ht;
 269
 270         assert(usess);
 271         assert(uchan);
 272         assert(event_name);
 273
 274         ht = uchan->events;
 275
 276         rcu_read_lock();
 277
 278         /*
 279          * We use a custom lookup since we need the iterator for the next_duplicate
 280          * call in the do while loop below.
 281          */
 282         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) event_name, lttng_ht_seed),
 283                         trace_ust_ht_match_event_by_name, event_name, &iter.iter);
 284         node = lttng_ht_iter_get_node_str(&iter);
 285         if (node == NULL) {
 286                 DBG2("Trace UST event NOT found by name %s", event_name);
 287                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 288                 goto error;
 289         }
 290
 291         do {
 292                 uevent = caa_container_of(node, struct ltt_ust_event, node);
 293                 assert(uevent);
 294
 295                 if (uevent->enabled == 0) {
 296                         /* It's already disabled so everything is OK */
 297                         goto next;
 298                 }
 299                 uevent->enabled = 0;
 300                 DBG2("Event UST %s disabled in channel %s", uevent->attr.name,
 301                                 uchan->name);
 302
 303                 if (!usess->active) {
 304                         goto next;
 305                 }
 306                 ret = ust_app_disable_event_glb(usess, uchan, uevent);
 307                 if (ret < 0 && ret != -LTTNG_UST_ERR_EXIST) {
 308                         ret = LTTNG_ERR_UST_DISABLE_FAIL;
 309                         goto error;
 310                 }
 311 next:
 312                 /* Get next duplicate event by name. */
 313                 cds_lfht_next_duplicate(ht->ht, trace_ust_ht_match_event_by_name,
 314                                 event_name, &iter.iter);
 315                 node = lttng_ht_iter_get_node_str(&iter);
 316         } while (node);
 317
 318         ret = LTTNG_OK;
 319
 320 error:
 321         rcu_read_unlock();
 322         return ret;
 323 }
 324
 325 /*
 326  * Disable all UST tracepoints for a channel from a UST session.
 327  */
 328 int event_ust_disable_all_tracepoints(struct ltt_ust_session *usess,
 329                 struct ltt_ust_channel *uchan)
 330 {
 331         int ret, i, size, error = 0;
 332         struct lttng_ht_iter iter;
 333         struct ltt_ust_event *uevent = NULL;
 334         struct lttng_event *events = NULL;
 335
 336         assert(usess);
 337         assert(uchan);
 338
 339         rcu_read_lock();
 340
 341         /* Disabling existing events */
 342         cds_lfht_for_each_entry(uchan->events->ht, &iter.iter, uevent,
 343                         node.node) {
 344                 if (uevent->enabled == 1) {
 345                         ret = event_ust_disable_tracepoint(usess, uchan,
 346                                         uevent->attr.name);
 347                         if (ret < 0) {
 348                                 error = LTTNG_ERR_UST_DISABLE_FAIL;
 349                                 continue;
 350                         }
 351                 }
 352         }
 353
 354         /* Get all UST available events */
 355         size = ust_app_list_events(&events);
 356         if (size < 0) {
 357                 ret = LTTNG_ERR_UST_LIST_FAIL;
 358                 goto error;
 359         }
 360
 361         for (i = 0; i < size; i++) {
 362                 ret = event_ust_disable_tracepoint(usess, uchan,
 363                                 events[i].name);
 364                 if (ret < 0) {
 365                         /* Continue to disable the rest... */
 366                         error = LTTNG_ERR_UST_DISABLE_FAIL;
 367                         continue;
 368                 }
 369         }
 370
 371         ret = error ? error : LTTNG_OK;
 372 error:
 373         rcu_read_unlock();
 374         free(events);
 375         return ret;
 376 }
 377
 378 /*
 379  * Enable all agent event for a given UST session.
 380  *
 381  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 382  */
 383 int event_agent_enable_all(struct ltt_ust_session *usess,
 384                 struct agent *agt, struct lttng_event *event,
 385                 struct lttng_filter_bytecode *filter ,char *filter_expression)
 386 {
 387         int ret;
 388         struct agent_event *aevent;
 389         struct lttng_ht_iter iter;
 390
 391         assert(usess);
 392
 393         DBG("Event agent enabling ALL events for session %" PRIu64, usess->id);
 394
 395         /* Enable event on agent application through TCP socket. */
 396         ret = event_agent_enable(usess, agt, event, filter, filter_expression);
 397         if (ret != LTTNG_OK) {
 398                 goto error;
 399         }
 400
 401         /* Flag every event that they are now enabled. */
 402         rcu_read_lock();
 403         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, aevent,
 404                         node.node) {
 405                 aevent->enabled = 1;
 406         }
 407         rcu_read_unlock();
 408
 409         ret = LTTNG_OK;
 410
 411 error:
 412         return ret;
 413 }
 414
 415 /*
 416  * Check if this event's filter requires the activation of application contexts
 417  * and enable them in the agent.
 418  * TODO: bytecode iterator does not support non-legacy application
 419  * contexts yet. Not an issue for now, since they are not generated by
 420  * the lttng-ctl library.
 421  */
 422 static int add_filter_app_ctx(struct lttng_filter_bytecode *bytecode,
 423                 const char *filter_expression, struct agent *agt)
 424 {
 425         int ret = LTTNG_OK;
 426         char *provider_name = NULL, *ctx_name = NULL;
 427         struct bytecode_symbol_iterator *it =
 428                         bytecode_symbol_iterator_create(bytecode);
 429
 430         if (!it) {
 431                 ret = LTTNG_ERR_NOMEM;
 432                 goto end;
 433         }
 434
 435         do {
 436                 struct lttng_event_context ctx;
 437                 const char *symbol_name =
 438                                 bytecode_symbol_iterator_get_name(it);
 439
 440                 if (parse_application_context(symbol_name, &provider_name,
 441                                 &ctx_name)) {
 442                         /* Not an application context. */
 443                         continue;
 444                 }
 445
 446                 ctx.ctx = LTTNG_EVENT_CONTEXT_APP_CONTEXT;
 447                 ctx.u.app_ctx.provider_name = provider_name;
 448                 ctx.u.app_ctx.ctx_name = ctx_name;
 449
 450                 /* Recognized an application context. */
 451                 DBG("Enabling event with filter expression \"%s\" requires enabling the %s:%s application context.",
 452                                 filter_expression, provider_name, ctx_name);
 453
 454                 ret = agent_add_context(&ctx, agt);
 455                 if (ret != LTTNG_OK) {
 456                         ERR("Failed to add application context %s:%s.",
 457                                         provider_name, ctx_name);
 458                         goto end;
 459                 }
 460
 461                 ret = agent_enable_context(&ctx, agt->domain);
 462                 if (ret != LTTNG_OK) {
 463                         ERR("Failed to enable application context %s:%s.",
 464                                         provider_name, ctx_name);
 465                         goto end;
 466                 }
 467
 468                 free(provider_name);
 469                 free(ctx_name);
 470                 provider_name = ctx_name = NULL;
 471         } while (bytecode_symbol_iterator_next(it) == 0);
 472 end:
 473         free(provider_name);
 474         free(ctx_name);
 475         bytecode_symbol_iterator_destroy(it);
 476         return ret;
 477 }
 478
 479 /*
 480  * Enable a single agent event for a given UST session.
 481  *
 482  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 483  */
 484 int event_agent_enable(struct ltt_ust_session *usess,
 485                 struct agent *agt, struct lttng_event *event,
 486                 struct lttng_filter_bytecode *filter,
 487                 char *filter_expression)
 488 {
 489         int ret, created = 0;
 490         struct agent_event *aevent;
 491
 492         assert(usess);
 493         assert(event);
 494         assert(agt);
 495
 496         DBG("Event agent enabling %s for session %" PRIu64 " with loglevel type %d "
 497                         ", loglevel %d and filter \"%s\"", event->name,
 498                         usess->id, event->loglevel_type, event->loglevel,
 499                         filter_expression ? filter_expression : "NULL");
 500
 501         aevent = agent_find_event(event->name, event->loglevel_type,
 502                         event->loglevel, filter_expression, agt);
 503         if (!aevent) {
 504                 aevent = agent_create_event(event->name, event->loglevel_type,
 505                                 event->loglevel, filter,
 506                                 filter_expression);
 507                 if (!aevent) {
 508                         ret = LTTNG_ERR_NOMEM;
 509                         goto error;
 510                 }
 511                 filter = NULL;
 512                 filter_expression = NULL;
 513                 created = 1;
 514         }
 515
 516         if (created && filter) {
 517                 ret = add_filter_app_ctx(filter, filter_expression, agt);
 518                 if (ret != LTTNG_OK) {
 519                         goto error;
 520                 }
 521         }
 522
 523         /* Already enabled? */
 524         if (aevent->enabled) {
 525                 ret = LTTNG_OK;
 526                 goto end;
 527         }
 528
 529         ret = agent_enable_event(aevent, agt->domain);
 530         if (ret != LTTNG_OK) {
 531                 goto error;
 532         }
 533
 534         /* If the event was created prior to the enable, add it to the domain. */
 535         if (created) {
 536                 agent_add_event(aevent, agt);
 537         }
 538
 539         ret = LTTNG_OK;
 540         goto end;
 541
 542 error:
 543         if (created) {
 544                 agent_destroy_event(aevent);
 545         }
 546 end:
 547         free(filter);
 548         free(filter_expression);
 549         return ret;
 550 }
 551
 552 /*
 553  * Return the default event name associated with the provided UST domain. Return
 554  * NULL on error.
 555  */
 556 const char *event_get_default_agent_ust_name(enum lttng_domain_type domain)
 557 {
 558         const char *default_event_name = NULL;
 559
 560         switch (domain) {
 561         case LTTNG_DOMAIN_LOG4J:
 562                 default_event_name = DEFAULT_LOG4J_EVENT_NAME;
 563                 break;
 564         case LTTNG_DOMAIN_JUL:
 565                 default_event_name = DEFAULT_JUL_EVENT_NAME;
 566                 break;
 567         case LTTNG_DOMAIN_PYTHON:
 568                 default_event_name = DEFAULT_PYTHON_EVENT_NAME;
 569                 break;
 570         default:
 571                 assert(0);
 572         }
 573
 574         return default_event_name;
 575 }
 576
 577 /*
 578  * Disable a given agent event for a given UST session.
 579  *
 580  * Must be called with the RCU read lock held.
 581  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 582  */
 583 static int event_agent_disable_one(struct ltt_ust_session *usess,
 584                 struct agent *agt, struct agent_event *aevent)
 585 {
 586         int ret;
 587         struct ltt_ust_event *uevent = NULL;
 588         struct ltt_ust_channel *uchan = NULL;
 589         const char *ust_event_name, *ust_channel_name;
 590
 591         assert(agt);
 592         assert(usess);
 593         assert(aevent);
 594
 595         DBG("Event agent disabling %s (loglevel type %d, loglevel value %d) for session %" PRIu64,
 596                 aevent->name, aevent->loglevel_type, aevent->loglevel_value,
 597                 usess->id);
 598
 599         /* Already disabled? */
 600         if (!aevent->enabled) {
 601                 goto end;
 602         }
 603
 604         if (agt->domain == LTTNG_DOMAIN_JUL) {
 605                 ust_channel_name = DEFAULT_JUL_CHANNEL_NAME;
 606         } else if (agt->domain == LTTNG_DOMAIN_LOG4J) {
 607                 ust_channel_name = DEFAULT_LOG4J_CHANNEL_NAME;
 608         } else if (agt->domain == LTTNG_DOMAIN_PYTHON) {
 609                 ust_channel_name = DEFAULT_PYTHON_CHANNEL_NAME;
 610         } else {
 611                 ret = LTTNG_ERR_INVALID;
 612                 goto error;
 613         }
 614
 615         /*
 616          * Disable it on the UST side. First get the channel reference then find
 617          * the event and finally disable it.
 618          */
 619         uchan = trace_ust_find_channel_by_name(usess->domain_global.channels,
 620                         (char *) ust_channel_name);
 621         if (!uchan) {
 622                 ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
 623                 goto error;
 624         }
 625
 626         ust_event_name = event_get_default_agent_ust_name(agt->domain);
 627         if (!ust_event_name) {
 628                 ret = LTTNG_ERR_FATAL;
 629                 goto error;
 630         }
 631
 632         /*
 633          * Agent UST event has its loglevel type forced to
 634          * LTTNG_UST_LOGLEVEL_ALL. The actual loglevel type/value filtering
 635          * happens thanks to an UST filter. The following -1 is actually
 636          * ignored since the type is LTTNG_UST_LOGLEVEL_ALL.
 637          */
 638         uevent = trace_ust_find_event(uchan->events, (char *) ust_event_name,
 639                         aevent->filter, LTTNG_UST_LOGLEVEL_ALL, -1, NULL);
 640         /* If the agent event exists, it must be available on the UST side. */
 641         assert(uevent);
 642
 643         if (usess->active) {
 644                 ret = ust_app_disable_event_glb(usess, uchan, uevent);
 645                 if (ret < 0 && ret != -LTTNG_UST_ERR_EXIST) {
 646                         ret = LTTNG_ERR_UST_DISABLE_FAIL;
 647                         goto error;
 648                 }
 649         }
 650
 651         /*
 652          * Flag event that it's disabled so the shadow copy on the ust app side
 653          * will disable it if an application shows up.
 654          */
 655         uevent->enabled = 0;
 656
 657         ret = agent_disable_event(aevent, agt->domain);
 658         if (ret != LTTNG_OK) {
 659                 goto error;
 660         }
 661
 662 end:
 663         return LTTNG_OK;
 664
 665 error:
 666         return ret;
 667 }
 668
 669 /*
 670  * Disable all agent events matching a given name for a given UST session.
 671  *
 672  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 673  */
 674 int event_agent_disable(struct ltt_ust_session *usess, struct agent *agt,
 675                 const char *event_name)
 676 {
 677         int ret = LTTNG_OK;
 678         struct agent_event *aevent;
 679         struct lttng_ht_iter iter;
 680         struct lttng_ht_node_str *node;
 681
 682         assert(agt);
 683         assert(usess);
 684         assert(event_name);
 685
 686         DBG("Event agent disabling %s (all loglevels) for session %" PRIu64, event_name, usess->id);
 687
 688         rcu_read_lock();
 689         agent_find_events_by_name(event_name, agt, &iter);
 690         node = lttng_ht_iter_get_node_str(&iter);
 691
 692         if (node == NULL) {
 693                 DBG2("Event agent NOT found by name %s", event_name);
 694                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 695                 goto end;
 696         }
 697
 698         do {
 699                 aevent = caa_container_of(node, struct agent_event, node);
 700                 ret = event_agent_disable_one(usess, agt, aevent);
 701
 702                 if (ret != LTTNG_OK) {
 703                         goto end;
 704                 }
 705
 706                 /* Get next duplicate agent event by name. */
 707                 agent_event_next_duplicate(event_name, agt, &iter);
 708                 node = lttng_ht_iter_get_node_str(&iter);
 709         } while (node);
 710 end:
 711         rcu_read_unlock();
 712         return ret;
 713 }
 714 /*
 715  * Disable all agent event for a given UST session.
 716  *
 717  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 718  */
 719 int event_agent_disable_all(struct ltt_ust_session *usess,
 720                 struct agent *agt)
 721 {
 722         int ret;
 723         struct agent_event *aevent;
 724         struct lttng_ht_iter iter;
 725
 726         assert(agt);
 727         assert(usess);
 728
 729         /*
 730          * Disable event on agent application. Continue to disable all other events
 731          * if the * event is not found.
 732          */
 733         ret = event_agent_disable(usess, agt, "*");
 734         if (ret != LTTNG_OK && ret != LTTNG_ERR_UST_EVENT_NOT_FOUND) {
 735                 goto error;
 736         }
 737
 738         /* Disable every event. */
 739         rcu_read_lock();
 740         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, aevent,
 741                         node.node) {
 742                 if (!aevent->enabled) {
 743                         continue;
 744                 }
 745
 746                 ret = event_agent_disable(usess, agt, aevent->name);
 747                 if (ret != LTTNG_OK) {
 748                         goto error_unlock;
 749                 }
 750         }
 751         ret = LTTNG_OK;
 752
 753 error_unlock:
 754         rcu_read_unlock();
 755 error:
 756         return ret;
 757 }