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         key.exclusion = event->exclusion;
  52
  53         node_ptr = cds_lfht_add_unique(ht->ht,
  54                         ht->hash_fct(event->node.key, lttng_ht_seed),
  55                         trace_ust_ht_match_event, &key, &event->node.node);
  56         assert(node_ptr == &event->node.node);
  57 }
  58
  59 /*
  60  * Setup a lttng_event used to enable *all* syscall tracing.
  61  */
  62 static void init_syscalls_kernel_event(struct lttng_event *event)
  63 {
  64         assert(event);
  65
  66         event->name[0] = '\0';
  67         /*
  68          * We use LTTNG_EVENT* here since the trace kernel creation will make the
  69          * right changes for the kernel.
  70          */
  71         event->type = LTTNG_EVENT_SYSCALL;
  72 }
  73
  74 /*
  75  * Disable kernel tracepoint event for a channel from the kernel session.
  76  */
  77 int event_kernel_disable_tracepoint(struct ltt_kernel_channel *kchan,
  78                 char *event_name)
  79 {
  80         int ret;
  81         struct ltt_kernel_event *kevent;
  82
  83         assert(kchan);
  84
  85         kevent = trace_kernel_get_event_by_name(event_name, kchan);
  86         if (kevent == NULL) {
  87                 ret = LTTNG_ERR_NO_EVENT;
  88                 goto error;
  89         }
  90
  91         ret = kernel_disable_event(kevent);
  92         if (ret < 0) {
  93                 ret = LTTNG_ERR_KERN_DISABLE_FAIL;
  94                 goto error;
  95         }
  96
  97         DBG("Kernel event %s disable for channel %s.",
  98                         kevent->event->name, kchan->channel->name);
  99
 100         ret = LTTNG_OK;
 101
 102 error:
 103         return ret;
 104 }
 105
 106 /*
 107  * Disable kernel tracepoint events for a channel from the kernel session.
 108  */
 109 int event_kernel_disable_all_tracepoints(struct ltt_kernel_channel *kchan)
 110 {
 111         int ret;
 112         struct ltt_kernel_event *kevent;
 113
 114         assert(kchan);
 115
 116         /* For each event in the kernel session */
 117         cds_list_for_each_entry(kevent, &kchan->events_list.head, list) {
 118                 ret = kernel_disable_event(kevent);
 119                 if (ret < 0) {
 120                         /* We continue disabling the rest */
 121                         continue;
 122                 }
 123         }
 124         ret = LTTNG_OK;
 125         return ret;
 126 }
 127
 128 /*
 129  * Disable kernel syscall events for a channel from the kernel session.
 130  */
 131 int event_kernel_disable_all_syscalls(struct ltt_kernel_channel *kchan)
 132 {
 133         ERR("Cannot disable syscall tracing for existing session. Please destroy session instead.");
 134         return LTTNG_OK;        /* Return OK so disable all succeeds */
 135 }
 136
 137 /*
 138  * Disable all kernel event for a channel from the kernel session.
 139  */
 140 int event_kernel_disable_all(struct ltt_kernel_channel *kchan)
 141 {
 142         int ret;
 143
 144         assert(kchan);
 145
 146         ret = event_kernel_disable_all_tracepoints(kchan);
 147         if (ret != LTTNG_OK)
 148                 return ret;
 149         ret = event_kernel_disable_all_syscalls(kchan);
 150         return ret;
 151 }
 152
 153 /*
 154  * Enable kernel tracepoint event for a channel from the kernel session.
 155  */
 156 int event_kernel_enable_tracepoint(struct ltt_kernel_channel *kchan,
 157                 struct lttng_event *event)
 158 {
 159         int ret;
 160         struct ltt_kernel_event *kevent;
 161
 162         assert(kchan);
 163         assert(event);
 164
 165         kevent = trace_kernel_get_event_by_name(event->name, kchan);
 166         if (kevent == NULL) {
 167                 ret = kernel_create_event(event, kchan);
 168                 if (ret < 0) {
 169                         switch (-ret) {
 170                         case EEXIST:
 171                                 ret = LTTNG_ERR_KERN_EVENT_EXIST;
 172                                 break;
 173                         case ENOSYS:
 174                                 ret = LTTNG_ERR_KERN_EVENT_ENOSYS;
 175                                 break;
 176                         default:
 177                                 ret = LTTNG_ERR_KERN_ENABLE_FAIL;
 178                                 break;
 179                         }
 180                         goto end;
 181                 }
 182         } else if (kevent->enabled == 0) {
 183                 ret = kernel_enable_event(kevent);
 184                 if (ret < 0) {
 185                         ret = LTTNG_ERR_KERN_ENABLE_FAIL;
 186                         goto end;
 187                 }
 188         } else {
 189                 /* At this point, the event is considered enabled */
 190                 ret = LTTNG_ERR_KERN_EVENT_EXIST;
 191                 goto end;
 192         }
 193
 194         ret = LTTNG_OK;
 195 end:
 196         return ret;
 197 }
 198
 199 /*
 200  * Enable all kernel tracepoint events of a channel of the kernel session.
 201  */
 202 int event_kernel_enable_all_tracepoints(struct ltt_kernel_channel *kchan,
 203                 int kernel_tracer_fd)
 204 {
 205         int size, i, ret;
 206         struct ltt_kernel_event *kevent;
 207         struct lttng_event *event_list = NULL;
 208
 209         assert(kchan);
 210
 211         /* For each event in the kernel session */
 212         cds_list_for_each_entry(kevent, &kchan->events_list.head, list) {
 213                 if (kevent->enabled == 0) {
 214                         ret = kernel_enable_event(kevent);
 215                         if (ret < 0) {
 216                                 /* Enable failed but still continue */
 217                                 continue;
 218                         }
 219                 }
 220         }
 221
 222         size = kernel_list_events(kernel_tracer_fd, &event_list);
 223         if (size < 0) {
 224                 ret = LTTNG_ERR_KERN_LIST_FAIL;
 225                 goto end;
 226         }
 227
 228         for (i = 0; i < size; i++) {
 229                 kevent = trace_kernel_get_event_by_name(event_list[i].name, kchan);
 230                 if (kevent == NULL) {
 231                         /* Default event type for enable all */
 232                         event_list[i].type = LTTNG_EVENT_TRACEPOINT;
 233                         /* Enable each single tracepoint event */
 234                         ret = kernel_create_event(&event_list[i], kchan);
 235                         if (ret < 0) {
 236                                 /* Ignore error here and continue */
 237                         }
 238                 }
 239         }
 240         free(event_list);
 241
 242         ret = LTTNG_OK;
 243 end:
 244         return ret;
 245 }
 246
 247 /*
 248  * Enable all kernel sycalls events of a channel of the kernel session.
 249  */
 250 int event_kernel_enable_all_syscalls(struct ltt_kernel_channel *kchan,
 251                 int kernel_tracer_fd)
 252 {
 253         int ret;
 254         struct lttng_event event;
 255
 256         assert(kchan);
 257
 258         init_syscalls_kernel_event(&event);
 259
 260         DBG("Enabling all syscall tracing");
 261
 262         ret = kernel_create_event(&event, kchan);
 263         if (ret < 0) {
 264                 if (ret == -EEXIST) {
 265                         ret = LTTNG_ERR_KERN_EVENT_EXIST;
 266                 } else {
 267                         ret = LTTNG_ERR_KERN_ENABLE_FAIL;
 268                 }
 269                 goto end;
 270         }
 271
 272         ret = LTTNG_OK;
 273 end:
 274         return ret;
 275 }
 276
 277 /*
 278  * Enable all kernel events of a channel of the kernel session.
 279  */
 280 int event_kernel_enable_all(struct ltt_kernel_channel *kchan,
 281                 int kernel_tracer_fd)
 282 {
 283         int tp_ret;
 284
 285         assert(kchan);
 286
 287         tp_ret = event_kernel_enable_all_tracepoints(kchan, kernel_tracer_fd);
 288         if (tp_ret != LTTNG_OK) {
 289                 goto end;
 290         }
 291
 292         /*
 293          * Reaching this code path means that all tracepoints were enabled without
 294          * errors so we ignore the error value of syscalls.
 295          *
 296          * At the moment, failing to enable syscalls on "lttng enable-event -a -k"
 297          * is not considered an error that need to be returned to the client since
 298          * tracepoints did not fail. Future work will allow us to send back
 299          * multiple errors to the client in one API call.
 300          */
 301         (void) event_kernel_enable_all_syscalls(kchan, kernel_tracer_fd);
 302
 303 end:
 304         return tp_ret;
 305 }
 306
 307 /*
 308  * ============================
 309  * UST : The Ultimate Frontier!
 310  * ============================
 311  */
 312
 313 /*
 314  * Enable all UST tracepoints for a channel from a UST session.
 315  */
 316 int event_ust_enable_all_tracepoints(struct ltt_ust_session *usess,
 317                 struct ltt_ust_channel *uchan,
 318                 char *filter_expression,
 319                 struct lttng_filter_bytecode *filter)
 320 {
 321         int ret, i, size;
 322         struct lttng_ht_iter iter;
 323         struct ltt_ust_event *uevent = NULL;
 324         struct lttng_event *events = NULL;
 325
 326         assert(usess);
 327         assert(uchan);
 328
 329         rcu_read_lock();
 330
 331         /* Enable existing events */
 332         cds_lfht_for_each_entry(uchan->events->ht, &iter.iter, uevent,
 333                         node.node) {
 334                 if (uevent->enabled == 0) {
 335                         ret = ust_app_enable_event_glb(usess, uchan, uevent);
 336                         if (ret < 0) {
 337                                 continue;
 338                         }
 339                         uevent->enabled = 1;
 340                 }
 341         }
 342
 343         /* Get all UST available events */
 344         size = ust_app_list_events(&events);
 345         if (size < 0) {
 346                 ret = LTTNG_ERR_UST_LIST_FAIL;
 347                 goto error;
 348         }
 349
 350         for (i = 0; i < size; i++) {
 351                 /*
 352                  * Check if event exist and if so, continue since it was enable
 353                  * previously.
 354                  */
 355                 uevent = trace_ust_find_event(uchan->events, events[i].name, filter,
 356                                 events[i].loglevel, NULL);
 357                 if (uevent != NULL) {
 358                         ret = ust_app_enable_event_pid(usess, uchan, uevent,
 359                                         events[i].pid);
 360                         if (ret < 0) {
 361                                 if (ret != -LTTNG_UST_ERR_EXIST) {
 362                                         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 363                                         goto error;
 364                                 }
 365                         }
 366                         continue;
 367                 }
 368
 369                 /* Create ust event */
 370                 uevent = trace_ust_create_event(&events[i], filter_expression,
 371                         filter, NULL);
 372                 if (uevent == NULL) {
 373                         ret = LTTNG_ERR_FATAL;
 374                         goto error_destroy;
 375                 }
 376
 377                 /* Create event for the specific PID */
 378                 ret = ust_app_enable_event_pid(usess, uchan, uevent,
 379                                 events[i].pid);
 380                 if (ret < 0) {
 381                         if (ret == -LTTNG_UST_ERR_EXIST) {
 382                                 ret = LTTNG_ERR_UST_EVENT_EXIST;
 383                                 goto error;
 384                         } else {
 385                                 ret = LTTNG_ERR_UST_ENABLE_FAIL;
 386                                 goto error_destroy;
 387                         }
 388                 }
 389
 390                 uevent->enabled = 1;
 391                 /* Add ltt ust event to channel */
 392                 rcu_read_lock();
 393                 add_unique_ust_event(uchan->events, uevent);
 394                 rcu_read_unlock();
 395         }
 396         free(events);
 397
 398         rcu_read_unlock();
 399         return LTTNG_OK;
 400
 401 error_destroy:
 402         trace_ust_destroy_event(uevent);
 403
 404 error:
 405         free(events);
 406         rcu_read_unlock();
 407         return ret;
 408 }
 409
 410 /*
 411  * Enable UST tracepoint event for a channel from a UST session.
 412  */
 413 int event_ust_enable_tracepoint(struct ltt_ust_session *usess,
 414                 struct ltt_ust_channel *uchan, struct lttng_event *event,
 415                 char *filter_expression,
 416                 struct lttng_filter_bytecode *filter,
 417                 struct lttng_event_exclusion *exclusion)
 418 {
 419         int ret = LTTNG_OK, to_create = 0;
 420         struct ltt_ust_event *uevent;
 421
 422         assert(usess);
 423         assert(uchan);
 424         assert(event);
 425
 426         rcu_read_lock();
 427
 428         uevent = trace_ust_find_event(uchan->events, event->name, filter,
 429                         event->loglevel, exclusion);
 430         if (uevent == NULL) {
 431                 uevent = trace_ust_create_event(event, filter_expression,
 432                         filter, exclusion);
 433                 if (uevent == NULL) {
 434                         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 435                         goto error;
 436                 }
 437
 438                 /* Valid to set it after the goto error since uevent is still NULL */
 439                 to_create = 1;
 440         }
 441
 442         if (uevent->enabled) {
 443                 /* It's already enabled so everything is OK */
 444                 ret = LTTNG_ERR_UST_EVENT_ENABLED;
 445                 goto end;
 446         }
 447
 448         uevent->enabled = 1;
 449
 450         if (to_create) {
 451                 /* Create event on all UST registered apps for session */
 452                 ret = ust_app_create_event_glb(usess, uchan, uevent);
 453         } else {
 454                 /* Enable event on all UST registered apps for session */
 455                 ret = ust_app_enable_event_glb(usess, uchan, uevent);
 456         }
 457
 458         if (ret < 0) {
 459                 if (ret == -LTTNG_UST_ERR_EXIST) {
 460                         ret = LTTNG_ERR_UST_EVENT_EXIST;
 461                         goto end;
 462                 } else {
 463                         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 464                         goto error;
 465                 }
 466         }
 467
 468         if (to_create) {
 469                 /* Add ltt ust event to channel */
 470                 add_unique_ust_event(uchan->events, uevent);
 471         }
 472
 473         DBG("Event UST %s %s in channel %s", uevent->attr.name,
 474                         to_create ? "created" : "enabled", uchan->name);
 475
 476         ret = LTTNG_OK;
 477
 478 end:
 479         rcu_read_unlock();
 480         return ret;
 481
 482 error:
 483         /*
 484          * Only destroy event on creation time (not enabling time) because if the
 485          * event is found in the channel (to_create == 0), it means that at some
 486          * point the enable_event worked and it's thus valid to keep it alive.
 487          * Destroying it also implies that we also destroy it's shadow copy to sync
 488          * everyone up.
 489          */
 490         if (to_create) {
 491                 /* In this code path, the uevent was not added to the hash table */
 492                 trace_ust_destroy_event(uevent);
 493         }
 494         rcu_read_unlock();
 495         return ret;
 496 }
 497
 498 /*
 499  * Disable UST tracepoint of a channel from a UST session.
 500  */
 501 int event_ust_disable_tracepoint(struct ltt_ust_session *usess,
 502                 struct ltt_ust_channel *uchan, char *event_name)
 503 {
 504         int ret;
 505         struct ltt_ust_event *uevent;
 506         struct lttng_ht_node_str *node;
 507         struct lttng_ht_iter iter;
 508         struct lttng_ht *ht;
 509
 510         assert(usess);
 511         assert(uchan);
 512         assert(event_name);
 513
 514         ht = uchan->events;
 515
 516         rcu_read_lock();
 517
 518         /*
 519          * We use a custom lookup since we need the iterator for the next_duplicate
 520          * call in the do while loop below.
 521          */
 522         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) event_name, lttng_ht_seed),
 523                         trace_ust_ht_match_event_by_name, event_name, &iter.iter);
 524         node = lttng_ht_iter_get_node_str(&iter);
 525         if (node == NULL) {
 526                 DBG2("Trace UST event NOT found by name %s", event_name);
 527                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 528                 goto error;
 529         }
 530
 531         do {
 532                 uevent = caa_container_of(node, struct ltt_ust_event, node);
 533                 assert(uevent);
 534
 535                 if (uevent->enabled == 0) {
 536                         /* It's already disabled so everything is OK */
 537                         goto next;
 538                 }
 539
 540                 ret = ust_app_disable_event_glb(usess, uchan, uevent);
 541                 if (ret < 0 && ret != -LTTNG_UST_ERR_EXIST) {
 542                         ret = LTTNG_ERR_UST_DISABLE_FAIL;
 543                         goto error;
 544                 }
 545                 uevent->enabled = 0;
 546
 547                 DBG2("Event UST %s disabled in channel %s", uevent->attr.name,
 548                                 uchan->name);
 549
 550 next:
 551                 /* Get next duplicate event by name. */
 552                 cds_lfht_next_duplicate(ht->ht, trace_ust_ht_match_event_by_name,
 553                                 event_name, &iter.iter);
 554                 node = lttng_ht_iter_get_node_str(&iter);
 555         } while (node);
 556
 557         ret = LTTNG_OK;
 558
 559 error:
 560         rcu_read_unlock();
 561         return ret;
 562 }
 563
 564 /*
 565  * Disable all UST tracepoints for a channel from a UST session.
 566  */
 567 int event_ust_disable_all_tracepoints(struct ltt_ust_session *usess,
 568                 struct ltt_ust_channel *uchan)
 569 {
 570         int ret, i, size;
 571         struct lttng_ht_iter iter;
 572         struct ltt_ust_event *uevent = NULL;
 573         struct lttng_event *events = NULL;
 574
 575         assert(usess);
 576         assert(uchan);
 577
 578         rcu_read_lock();
 579
 580         /* Disabling existing events */
 581         cds_lfht_for_each_entry(uchan->events->ht, &iter.iter, uevent,
 582                         node.node) {
 583                 if (uevent->enabled == 1) {
 584                         ret = event_ust_disable_tracepoint(usess, uchan,
 585                                         uevent->attr.name);
 586                         if (ret < 0) {
 587                                 continue;
 588                         }
 589                 }
 590         }
 591
 592         /* Get all UST available events */
 593         size = ust_app_list_events(&events);
 594         if (size < 0) {
 595                 ret = LTTNG_ERR_UST_LIST_FAIL;
 596                 goto error;
 597         }
 598
 599         for (i = 0; i < size; i++) {
 600                 ret = event_ust_disable_tracepoint(usess, uchan,
 601                                 events[i].name);
 602                 if (ret != LTTNG_OK) {
 603                         /* Continue to disable the rest... */
 604                         continue;
 605                 }
 606         }
 607         free(events);
 608
 609         rcu_read_unlock();
 610         return LTTNG_OK;
 611
 612 error:
 613         free(events);
 614         rcu_read_unlock();
 615         return ret;
 616 }
 617
 618 /*
 619  * Enable all JUL event for a given UST session.
 620  *
 621  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 622  */
 623 int event_jul_enable_all(struct ltt_ust_session *usess,
 624                 struct lttng_event *event)
 625 {
 626         int ret;
 627         struct jul_event *jevent;
 628         struct lttng_ht_iter iter;
 629
 630         assert(usess);
 631
 632         DBG("Event JUL enabling ALL events for session %" PRIu64, usess->id);
 633
 634         /* Enable event on JUL application through TCP socket. */
 635         ret = event_jul_enable(usess, event);
 636         if (ret != LTTNG_OK) {
 637                 goto error;
 638         }
 639
 640         /* Flag every event that they are now enabled. */
 641         rcu_read_lock();
 642         cds_lfht_for_each_entry(usess->domain_jul.events->ht, &iter.iter, jevent,
 643                         node.node) {
 644                 jevent->enabled = 1;
 645         }
 646         rcu_read_unlock();
 647
 648         ret = LTTNG_OK;
 649
 650 error:
 651         return ret;
 652 }
 653
 654 /*
 655  * Enable a single JUL event for a given UST session.
 656  *
 657  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 658  */
 659 int event_jul_enable(struct ltt_ust_session *usess, struct lttng_event *event)
 660 {
 661         int ret, created = 0;
 662         struct jul_event *jevent;
 663
 664         assert(usess);
 665         assert(event);
 666
 667         DBG("Event JUL enabling %s for session %" PRIu64 " with loglevel type %d "
 668                         "and loglevel %d", event->name, usess->id, event->loglevel_type,
 669                         event->loglevel);
 670
 671         jevent = jul_find_event(event->name, event->loglevel, &usess->domain_jul);
 672         if (!jevent) {
 673                 jevent = jul_create_event(event->name);
 674                 if (!jevent) {
 675                         ret = LTTNG_ERR_NOMEM;
 676                         goto error;
 677                 }
 678                 jevent->loglevel = event->loglevel;
 679                 jevent->loglevel_type = event->loglevel_type;
 680                 created = 1;
 681         }
 682
 683         /* Already enabled? */
 684         if (jevent->enabled) {
 685                 goto end;
 686         }
 687
 688         ret = jul_enable_event(jevent);
 689         if (ret != LTTNG_OK) {
 690                 goto error;
 691         }
 692
 693         /* If the event was created prior to the enable, add it to the domain. */
 694         if (created) {
 695                 jul_add_event(jevent, &usess->domain_jul);
 696         }
 697
 698 end:
 699         return LTTNG_OK;
 700
 701 error:
 702         if (created) {
 703                 jul_destroy_event(jevent);
 704         }
 705         return ret;
 706 }
 707
 708 /*
 709  * Disable a single JUL event for a given UST session.
 710  *
 711  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 712  */
 713 int event_jul_disable(struct ltt_ust_session *usess, char *event_name)
 714 {
 715         int ret;
 716         struct jul_event *jevent;
 717
 718         assert(usess);
 719         assert(event_name);
 720
 721         DBG("Event JUL disabling %s for session %" PRIu64, event_name, usess->id);
 722
 723         jevent = jul_find_event_by_name(event_name, &usess->domain_jul);
 724         if (!jevent) {
 725                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 726                 goto error;
 727         }
 728
 729         /* Already disabled? */
 730         if (!jevent->enabled) {
 731                 goto end;
 732         }
 733
 734         ret = jul_disable_event(jevent);
 735         if (ret != LTTNG_OK) {
 736                 goto error;
 737         }
 738
 739 end:
 740         return LTTNG_OK;
 741
 742 error:
 743         return ret;
 744 }
 745 /*
 746  * Disable all JUL event for a given UST session.
 747  *
 748  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 749  */
 750 int event_jul_disable_all(struct ltt_ust_session *usess)
 751 {
 752         int ret, do_disable = 0;
 753         struct jul_event *jevent;
 754         struct lttng_ht_iter iter;
 755
 756         assert(usess);
 757
 758         /* Enable event on JUL application through TCP socket. */
 759         ret = event_jul_disable(usess, "*");
 760         if (ret != LTTNG_OK) {
 761                 if (ret == LTTNG_ERR_UST_EVENT_NOT_FOUND) {
 762                         /*
 763                          * This means that no enable all was done before but still a user
 764                          * could want to disable everything even though the * wild card
 765                          * event does not exists.
 766                          */
 767                         do_disable = 1;
 768                 } else {
 769                         goto error;
 770                 }
 771         }
 772
 773         /* Flag every event that they are now enabled. */
 774         rcu_read_lock();
 775         cds_lfht_for_each_entry(usess->domain_jul.events->ht, &iter.iter, jevent,
 776                         node.node) {
 777                 if (jevent->enabled && do_disable) {
 778                         ret = event_jul_disable(usess, jevent->name);
 779                         if (ret != LTTNG_OK) {
 780                                 rcu_read_unlock();
 781                                 goto error;
 782                         }
 783                 }
 784                 jevent->enabled = 0;
 785         }
 786         rcu_read_unlock();
 787
 788         ret = LTTNG_OK;
 789
 790 error:
 791         return ret;
 792 }