src/bin/lttng-sessiond/event.c

   1 /*
   2  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License, version 2 only,
   6  * as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _GNU_SOURCE
  19 #include <errno.h>
  20 #include <urcu/list.h>
  21 #include <string.h>
  22
  23 #include <lttng/lttng.h>
  24 #include <common/error.h>
  25 #include <common/sessiond-comm/sessiond-comm.h>
  26
  27 #include "channel.h"
  28 #include "event.h"
  29 #include "kernel.h"
  30 #include "ust-ctl.h"
  31 #include "ust-app.h"
  32 #include "trace-kernel.h"
  33 #include "trace-ust.h"
  34
  35 /*
  36  * Add unique UST event based on the event name, filter bytecode and loglevel.
  37  */
  38 static void add_unique_ust_event(struct lttng_ht *ht,
  39                 struct ltt_ust_event *event)
  40 {
  41         struct cds_lfht_node *node_ptr;
  42         struct ltt_ust_ht_key key;
  43
  44         assert(ht);
  45         assert(ht->ht);
  46         assert(event);
  47
  48         key.name = event->attr.name;
  49         key.filter = (struct lttng_filter_bytecode *) event->filter;
  50         key.loglevel = event->attr.loglevel;
  51
  52         node_ptr = cds_lfht_add_unique(ht->ht,
  53                         ht->hash_fct(event->node.key, lttng_ht_seed),
  54                         trace_ust_ht_match_event, &key, &event->node.node);
  55         assert(node_ptr == &event->node.node);
  56 }
  57
  58 /*
  59  * Setup a lttng_event used to enable *all* syscall tracing.
  60  */
  61 static void init_syscalls_kernel_event(struct lttng_event *event)
  62 {
  63         assert(event);
  64
  65         event->name[0] = '\0';
  66         /*
  67          * We use LTTNG_EVENT* here since the trace kernel creation will make the
  68          * right changes for the kernel.
  69          */
  70         event->type = LTTNG_EVENT_SYSCALL;
  71 }
  72
  73 /*
  74  * Disable kernel tracepoint event for a channel from the kernel session.
  75  */
  76 int event_kernel_disable_tracepoint(struct ltt_kernel_channel *kchan,
  77                 char *event_name)
  78 {
  79         int ret;
  80         struct ltt_kernel_event *kevent;
  81
  82         assert(kchan);
  83
  84         kevent = trace_kernel_get_event_by_name(event_name, kchan);
  85         if (kevent == NULL) {
  86                 ret = LTTNG_ERR_NO_EVENT;
  87                 goto error;
  88         }
  89
  90         ret = kernel_disable_event(kevent);
  91         if (ret < 0) {
  92                 ret = LTTNG_ERR_KERN_DISABLE_FAIL;
  93                 goto error;
  94         }
  95
  96         DBG("Kernel event %s disable for channel %s.",
  97                         kevent->event->name, kchan->channel->name);
  98
  99         ret = LTTNG_OK;
 100
 101 error:
 102         return ret;
 103 }
 104
 105 /*
 106  * Disable kernel tracepoint events for a channel from the kernel session.
 107  */
 108 int event_kernel_disable_all_tracepoints(struct ltt_kernel_channel *kchan)
 109 {
 110         int ret;
 111         struct ltt_kernel_event *kevent;
 112
 113         assert(kchan);
 114
 115         /* For each event in the kernel session */
 116         cds_list_for_each_entry(kevent, &kchan->events_list.head, list) {
 117                 ret = kernel_disable_event(kevent);
 118                 if (ret < 0) {
 119                         /* We continue disabling the rest */
 120                         continue;
 121                 }
 122         }
 123         ret = LTTNG_OK;
 124         return ret;
 125 }
 126
 127 /*
 128  * Disable kernel syscall events for a channel from the kernel session.
 129  */
 130 int event_kernel_disable_all_syscalls(struct ltt_kernel_channel *kchan)
 131 {
 132         ERR("Cannot disable syscall tracing for existing session. Please destroy session instead.");
 133         return LTTNG_OK;        /* Return OK so disable all succeeds */
 134 }
 135
 136 /*
 137  * Disable all kernel event for a channel from the kernel session.
 138  */
 139 int event_kernel_disable_all(struct ltt_kernel_channel *kchan)
 140 {
 141         int ret;
 142
 143         assert(kchan);
 144
 145         ret = event_kernel_disable_all_tracepoints(kchan);
 146         if (ret != LTTNG_OK)
 147                 return ret;
 148         ret = event_kernel_disable_all_syscalls(kchan);
 149         return ret;
 150 }
 151
 152 /*
 153  * Enable kernel tracepoint event for a channel from the kernel session.
 154  */
 155 int event_kernel_enable_tracepoint(struct ltt_kernel_channel *kchan,
 156                 struct lttng_event *event)
 157 {
 158         int ret;
 159         struct ltt_kernel_event *kevent;
 160
 161         assert(kchan);
 162         assert(event);
 163
 164         kevent = trace_kernel_get_event_by_name(event->name, kchan);
 165         if (kevent == NULL) {
 166                 ret = kernel_create_event(event, kchan);
 167                 if (ret < 0) {
 168                         switch (-ret) {
 169                         case EEXIST:
 170                                 ret = LTTNG_ERR_KERN_EVENT_EXIST;
 171                                 break;
 172                         case ENOSYS:
 173                                 ret = LTTNG_ERR_KERN_EVENT_ENOSYS;
 174                                 break;
 175                         default:
 176                                 ret = LTTNG_ERR_KERN_ENABLE_FAIL;
 177                                 break;
 178                         }
 179                         goto end;
 180                 }
 181         } else if (kevent->enabled == 0) {
 182                 ret = kernel_enable_event(kevent);
 183                 if (ret < 0) {
 184                         ret = LTTNG_ERR_KERN_ENABLE_FAIL;
 185                         goto end;
 186                 }
 187         } else {
 188                 /* At this point, the event is considered enabled */
 189                 ret = LTTNG_ERR_KERN_EVENT_EXIST;
 190                 goto end;
 191         }
 192
 193         ret = LTTNG_OK;
 194 end:
 195         return ret;
 196 }
 197
 198 /*
 199  * Enable all kernel tracepoint events of a channel of the kernel session.
 200  */
 201 int event_kernel_enable_all_tracepoints(struct ltt_kernel_channel *kchan,
 202                 int kernel_tracer_fd)
 203 {
 204         int size, i, ret;
 205         struct ltt_kernel_event *kevent;
 206         struct lttng_event *event_list = NULL;
 207
 208         assert(kchan);
 209
 210         /* For each event in the kernel session */
 211         cds_list_for_each_entry(kevent, &kchan->events_list.head, list) {
 212                 if (kevent->enabled == 0) {
 213                         ret = kernel_enable_event(kevent);
 214                         if (ret < 0) {
 215                                 /* Enable failed but still continue */
 216                                 continue;
 217                         }
 218                 }
 219         }
 220
 221         size = kernel_list_events(kernel_tracer_fd, &event_list);
 222         if (size < 0) {
 223                 ret = LTTNG_ERR_KERN_LIST_FAIL;
 224                 goto end;
 225         }
 226
 227         for (i = 0; i < size; i++) {
 228                 kevent = trace_kernel_get_event_by_name(event_list[i].name, kchan);
 229                 if (kevent == NULL) {
 230                         /* Default event type for enable all */
 231                         event_list[i].type = LTTNG_EVENT_TRACEPOINT;
 232                         /* Enable each single tracepoint event */
 233                         ret = kernel_create_event(&event_list[i], kchan);
 234                         if (ret < 0) {
 235                                 /* Ignore error here and continue */
 236                         }
 237                 }
 238         }
 239         free(event_list);
 240
 241         ret = LTTNG_OK;
 242 end:
 243         return ret;
 244 }
 245
 246 /*
 247  * Enable all kernel sycalls events of a channel of the kernel session.
 248  */
 249 int event_kernel_enable_all_syscalls(struct ltt_kernel_channel *kchan,
 250                 int kernel_tracer_fd)
 251 {
 252         int ret;
 253         struct lttng_event event;
 254
 255         assert(kchan);
 256
 257         init_syscalls_kernel_event(&event);
 258
 259         DBG("Enabling all syscall tracing");
 260
 261         ret = kernel_create_event(&event, kchan);
 262         if (ret < 0) {
 263                 if (ret == -EEXIST) {
 264                         ret = LTTNG_ERR_KERN_EVENT_EXIST;
 265                 } else {
 266                         ret = LTTNG_ERR_KERN_ENABLE_FAIL;
 267                 }
 268                 goto end;
 269         }
 270
 271         ret = LTTNG_OK;
 272 end:
 273         return ret;
 274 }
 275
 276 /*
 277  * Enable all kernel events of a channel of the kernel session.
 278  */
 279 int event_kernel_enable_all(struct ltt_kernel_channel *kchan,
 280                 int kernel_tracer_fd)
 281 {
 282         int tp_ret;
 283
 284         assert(kchan);
 285
 286         tp_ret = event_kernel_enable_all_tracepoints(kchan, kernel_tracer_fd);
 287         if (tp_ret != LTTNG_OK) {
 288                 goto end;
 289         }
 290
 291         /*
 292          * Reaching this code path means that all tracepoints were enabled without
 293          * errors so we ignore the error value of syscalls.
 294          *
 295          * At the moment, failing to enable syscalls on "lttng enable-event -a -k"
 296          * is not considered an error that need to be returned to the client since
 297          * tracepoints did not fail. Future work will allow us to send back
 298          * multiple errors to the client in one API call.
 299          */
 300         (void) event_kernel_enable_all_syscalls(kchan, kernel_tracer_fd);
 301
 302 end:
 303         return tp_ret;
 304 }
 305
 306 /*
 307  * ============================
 308  * UST : The Ultimate Frontier!
 309  * ============================
 310  */
 311
 312 /*
 313  * Enable all UST tracepoints for a channel from a UST session.
 314  */
 315 int event_ust_enable_all_tracepoints(struct ltt_ust_session *usess,
 316                 struct ltt_ust_channel *uchan, struct lttng_filter_bytecode *filter)
 317 {
 318         int ret, i, size;
 319         struct lttng_ht_iter iter;
 320         struct ltt_ust_event *uevent = NULL;
 321         struct lttng_event *events = NULL;
 322
 323         assert(usess);
 324         assert(uchan);
 325
 326         rcu_read_lock();
 327
 328         /* Enable existing events */
 329         cds_lfht_for_each_entry(uchan->events->ht, &iter.iter, uevent,
 330                         node.node) {
 331                 if (uevent->enabled == 0) {
 332                         ret = ust_app_enable_event_glb(usess, uchan, uevent);
 333                         if (ret < 0) {
 334                                 continue;
 335                         }
 336                         uevent->enabled = 1;
 337                 }
 338         }
 339
 340         /* Get all UST available events */
 341         size = ust_app_list_events(&events);
 342         if (size < 0) {
 343                 ret = LTTNG_ERR_UST_LIST_FAIL;
 344                 goto error;
 345         }
 346
 347         for (i = 0; i < size; i++) {
 348                 /*
 349                  * Check if event exist and if so, continue since it was enable
 350                  * previously.
 351                  */
 352                 uevent = trace_ust_find_event(uchan->events, events[i].name, filter,
 353                                 events[i].loglevel);
 354                 if (uevent != NULL) {
 355                         ret = ust_app_enable_event_pid(usess, uchan, uevent,
 356                                         events[i].pid);
 357                         if (ret < 0) {
 358                                 if (ret != -LTTNG_UST_ERR_EXIST) {
 359                                         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 360                                         goto error;
 361                                 }
 362                         }
 363                         continue;
 364                 }
 365
 366                 /* Create ust event */
 367                 uevent = trace_ust_create_event(&events[i], filter, NULL);
 368                 if (uevent == NULL) {
 369                         ret = LTTNG_ERR_FATAL;
 370                         goto error_destroy;
 371                 }
 372
 373                 /* Create event for the specific PID */
 374                 ret = ust_app_enable_event_pid(usess, uchan, uevent,
 375                                 events[i].pid);
 376                 if (ret < 0) {
 377                         if (ret == -LTTNG_UST_ERR_EXIST) {
 378                                 ret = LTTNG_ERR_UST_EVENT_EXIST;
 379                                 goto error;
 380                         } else {
 381                                 ret = LTTNG_ERR_UST_ENABLE_FAIL;
 382                                 goto error_destroy;
 383                         }
 384                 }
 385
 386                 uevent->enabled = 1;
 387                 /* Add ltt ust event to channel */
 388                 rcu_read_lock();
 389                 add_unique_ust_event(uchan->events, uevent);
 390                 rcu_read_unlock();
 391         }
 392         free(events);
 393
 394         rcu_read_unlock();
 395         return LTTNG_OK;
 396
 397 error_destroy:
 398         trace_ust_destroy_event(uevent);
 399
 400 error:
 401         free(events);
 402         rcu_read_unlock();
 403         return ret;
 404 }
 405
 406 /*
 407  * Enable UST tracepoint event for a channel from a UST session.
 408  */
 409 int event_ust_enable_tracepoint(struct ltt_ust_session *usess,
 410                 struct ltt_ust_channel *uchan, struct lttng_event *event,
 411                 struct lttng_filter_bytecode *filter,
 412                 struct lttng_event_exclusion *exclusion)
 413 {
 414         int ret = LTTNG_OK, to_create = 0;
 415         struct ltt_ust_event *uevent;
 416
 417         assert(usess);
 418         assert(uchan);
 419         assert(event);
 420
 421         rcu_read_lock();
 422
 423         uevent = trace_ust_find_event(uchan->events, event->name, filter,
 424                         event->loglevel);
 425         if (uevent == NULL) {
 426                 uevent = trace_ust_create_event(event, filter, exclusion);
 427                 if (uevent == NULL) {
 428                         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 429                         goto error;
 430                 }
 431
 432                 /* Valid to set it after the goto error since uevent is still NULL */
 433                 to_create = 1;
 434         }
 435
 436         if (uevent->enabled) {
 437                 /* It's already enabled so everything is OK */
 438                 ret = LTTNG_ERR_UST_EVENT_ENABLED;
 439                 goto end;
 440         }
 441
 442         uevent->enabled = 1;
 443
 444         if (to_create) {
 445                 /* Create event on all UST registered apps for session */
 446                 ret = ust_app_create_event_glb(usess, uchan, uevent);
 447         } else {
 448                 /* Enable event on all UST registered apps for session */
 449                 ret = ust_app_enable_event_glb(usess, uchan, uevent);
 450         }
 451
 452         if (ret < 0) {
 453                 if (ret == -LTTNG_UST_ERR_EXIST) {
 454                         ret = LTTNG_ERR_UST_EVENT_EXIST;
 455                         goto end;
 456                 } else {
 457                         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 458                         goto error;
 459                 }
 460         }
 461
 462         if (to_create) {
 463                 /* Add ltt ust event to channel */
 464                 add_unique_ust_event(uchan->events, uevent);
 465         }
 466
 467         DBG("Event UST %s %s in channel %s", uevent->attr.name,
 468                         to_create ? "created" : "enabled", uchan->name);
 469
 470         ret = LTTNG_OK;
 471
 472 end:
 473         rcu_read_unlock();
 474         return ret;
 475
 476 error:
 477         /*
 478          * Only destroy event on creation time (not enabling time) because if the
 479          * event is found in the channel (to_create == 0), it means that at some
 480          * point the enable_event worked and it's thus valid to keep it alive.
 481          * Destroying it also implies that we also destroy it's shadow copy to sync
 482          * everyone up.
 483          */
 484         if (to_create) {
 485                 /* In this code path, the uevent was not added to the hash table */
 486                 trace_ust_destroy_event(uevent);
 487         }
 488         rcu_read_unlock();
 489         return ret;
 490 }
 491
 492 /*
 493  * Disable UST tracepoint of a channel from a UST session.
 494  */
 495 int event_ust_disable_tracepoint(struct ltt_ust_session *usess,
 496                 struct ltt_ust_channel *uchan, char *event_name)
 497 {
 498         int ret;
 499         struct ltt_ust_event *uevent;
 500         struct lttng_ht_node_str *node;
 501         struct lttng_ht_iter iter;
 502         struct lttng_ht *ht;
 503
 504         assert(usess);
 505         assert(uchan);
 506         assert(event_name);
 507
 508         ht = uchan->events;
 509
 510         rcu_read_lock();
 511
 512         /*
 513          * We use a custom lookup since we need the iterator for the next_duplicate
 514          * call in the do while loop below.
 515          */
 516         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) event_name, lttng_ht_seed),
 517                         trace_ust_ht_match_event_by_name, event_name, &iter.iter);
 518         node = lttng_ht_iter_get_node_str(&iter);
 519         if (node == NULL) {
 520                 DBG2("Trace UST event NOT found by name %s", event_name);
 521                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 522                 goto error;
 523         }
 524
 525         do {
 526                 uevent = caa_container_of(node, struct ltt_ust_event, node);
 527                 assert(uevent);
 528
 529                 if (uevent->enabled == 0) {
 530                         /* It's already disabled so everything is OK */
 531                         goto next;
 532                 }
 533
 534                 ret = ust_app_disable_event_glb(usess, uchan, uevent);
 535                 if (ret < 0 && ret != -LTTNG_UST_ERR_EXIST) {
 536                         ret = LTTNG_ERR_UST_DISABLE_FAIL;
 537                         goto error;
 538                 }
 539                 uevent->enabled = 0;
 540
 541                 DBG2("Event UST %s disabled in channel %s", uevent->attr.name,
 542                                 uchan->name);
 543
 544 next:
 545                 /* Get next duplicate event by name. */
 546                 cds_lfht_next_duplicate(ht->ht, trace_ust_ht_match_event_by_name,
 547                                 event_name, &iter.iter);
 548                 node = lttng_ht_iter_get_node_str(&iter);
 549         } while (node);
 550
 551         ret = LTTNG_OK;
 552
 553 error:
 554         rcu_read_unlock();
 555         return ret;
 556 }
 557
 558 /*
 559  * Disable all UST tracepoints for a channel from a UST session.
 560  */
 561 int event_ust_disable_all_tracepoints(struct ltt_ust_session *usess,
 562                 struct ltt_ust_channel *uchan)
 563 {
 564         int ret, i, size;
 565         struct lttng_ht_iter iter;
 566         struct ltt_ust_event *uevent = NULL;
 567         struct lttng_event *events = NULL;
 568
 569         assert(usess);
 570         assert(uchan);
 571
 572         rcu_read_lock();
 573
 574         /* Disabling existing events */
 575         cds_lfht_for_each_entry(uchan->events->ht, &iter.iter, uevent,
 576                         node.node) {
 577                 if (uevent->enabled == 1) {
 578                         ret = event_ust_disable_tracepoint(usess, uchan,
 579                                         uevent->attr.name);
 580                         if (ret < 0) {
 581                                 continue;
 582                         }
 583                 }
 584         }
 585
 586         /* Get all UST available events */
 587         size = ust_app_list_events(&events);
 588         if (size < 0) {
 589                 ret = LTTNG_ERR_UST_LIST_FAIL;
 590                 goto error;
 591         }
 592
 593         for (i = 0; i < size; i++) {
 594                 ret = event_ust_disable_tracepoint(usess, uchan,
 595                                 events[i].name);
 596                 if (ret != LTTNG_OK) {
 597                         /* Continue to disable the rest... */
 598                         continue;
 599                 }
 600         }
 601         free(events);
 602
 603         rcu_read_unlock();
 604         return LTTNG_OK;
 605
 606 error:
 607         free(events);
 608         rcu_read_unlock();
 609         return ret;
 610 }
 611
 612 /*
 613  * Enable all JUL event for a given UST session.
 614  *
 615  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 616  */
 617 int event_jul_enable_all(struct ltt_ust_session *usess)
 618 {
 619         int ret;
 620         struct jul_event *jevent;
 621         struct lttng_event event;
 622         struct lttng_ht_iter iter;
 623
 624         assert(usess);
 625
 626         DBG("Event JUL enabling ALL events for session %" PRIu64, usess->id);
 627
 628         /* Create the * wildcard event name for the Java agent. */
 629         memset(event.name, 0, sizeof(event.name));
 630         strncpy(event.name, "*", sizeof(event.name));
 631         event.name[sizeof(event.name) - 1] = '\0';
 632
 633         /* Enable event on JUL application through TCP socket. */
 634         ret = event_jul_enable(usess, &event);
 635         if (ret != LTTNG_OK) {
 636                 goto error;
 637         }
 638
 639         /* Flag every event that they are now enabled. */
 640         rcu_read_lock();
 641         cds_lfht_for_each_entry(usess->domain_jul.events->ht, &iter.iter, jevent,
 642                         node.node) {
 643                 jevent->enabled = 1;
 644         }
 645         rcu_read_unlock();
 646
 647         ret = LTTNG_OK;
 648
 649 error:
 650         return ret;
 651 }
 652
 653 /*
 654  * Enable a single JUL event for a given UST session.
 655  *
 656  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 657  */
 658 int event_jul_enable(struct ltt_ust_session *usess, struct lttng_event *event)
 659 {
 660         int ret, created = 0;
 661         struct jul_event *jevent;
 662
 663         assert(usess);
 664         assert(event);
 665
 666         DBG("Event JUL enabling %s for session %" PRIu64, event->name, usess->id);
 667
 668         jevent = jul_find_by_name(event->name, &usess->domain_jul);
 669         if (!jevent) {
 670                 jevent = jul_create_event(event->name);
 671                 if (!jevent) {
 672                         ret = LTTNG_ERR_NOMEM;
 673                         goto error;
 674                 }
 675                 created = 1;
 676         }
 677
 678         /* Already enabled? */
 679         if (jevent->enabled) {
 680                 goto end;
 681         }
 682
 683         ret = jul_enable_event(jevent);
 684         if (ret != LTTNG_OK) {
 685                 goto error;
 686         }
 687
 688         /* If the event was created prior to the enable, add it to the domain. */
 689         if (created) {
 690                 jul_add_event(jevent, &usess->domain_jul);
 691         }
 692
 693 end:
 694         return LTTNG_OK;
 695
 696 error:
 697         if (created) {
 698                 jul_destroy_event(jevent);
 699         }
 700         return ret;
 701 }
 702
 703 /*
 704  * Disable a single JUL event for a given UST session.
 705  *
 706  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 707  */
 708 int event_jul_disable(struct ltt_ust_session *usess, char *event_name)
 709 {
 710         int ret;
 711         struct jul_event *jevent;
 712
 713         assert(usess);
 714         assert(event_name);
 715
 716         DBG("Event JUL disabling %s for session %" PRIu64, event_name, usess->id);
 717
 718         jevent = jul_find_by_name(event_name, &usess->domain_jul);
 719         if (!jevent) {
 720                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 721                 goto error;
 722         }
 723
 724         /* Already disabled? */
 725         if (!jevent->enabled) {
 726                 goto end;
 727         }
 728
 729         ret = jul_disable_event(jevent);
 730         if (ret != LTTNG_OK) {
 731                 goto error;
 732         }
 733
 734 end:
 735         return LTTNG_OK;
 736
 737 error:
 738         return ret;
 739 }
 740 /*
 741  * Disable all JUL event for a given UST session.
 742  *
 743  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 744  */
 745 int event_jul_disable_all(struct ltt_ust_session *usess)
 746 {
 747         int ret, do_disable = 0;
 748         struct jul_event *jevent;
 749         struct lttng_ht_iter iter;
 750
 751         assert(usess);
 752
 753         /* Enable event on JUL application through TCP socket. */
 754         ret = event_jul_disable(usess, "*");
 755         if (ret != LTTNG_OK) {
 756                 if (ret == LTTNG_ERR_UST_EVENT_NOT_FOUND) {
 757                         /*
 758                          * This means that no enable all was done before but still a user
 759                          * could want to disable everything even though the * wild card
 760                          * event does not exists.
 761                          */
 762                         do_disable = 1;
 763                 } else {
 764                         goto error;
 765                 }
 766         }
 767
 768         /* Flag every event that they are now enabled. */
 769         rcu_read_lock();
 770         cds_lfht_for_each_entry(usess->domain_jul.events->ht, &iter.iter, jevent,
 771                         node.node) {
 772                 if (jevent->enabled && do_disable) {
 773                         ret = event_jul_disable(usess, jevent->name);
 774                         if (ret != LTTNG_OK) {
 775                                 rcu_read_unlock();
 776                                 goto error;
 777                         }
 778                 }
 779                 jevent->enabled = 0;
 780         }
 781         rcu_read_unlock();
 782
 783         ret = LTTNG_OK;
 784
 785 error:
 786         return ret;
 787 }