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 #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
  28 #include "channel.h"
  29 #include "event.h"
  30 #include "kernel.h"
  31 #include "lttng-sessiond.h"
  32 #include "ust-ctl.h"
  33 #include "ust-app.h"
  34 #include "trace-kernel.h"
  35 #include "trace-ust.h"
  36
  37 /*
  38  * Add unique UST event based on the event name, filter bytecode and loglevel.
  39  */
  40 static void add_unique_ust_event(struct lttng_ht *ht,
  41                 struct ltt_ust_event *event)
  42 {
  43         struct cds_lfht_node *node_ptr;
  44         struct ltt_ust_ht_key key;
  45
  46         assert(ht);
  47         assert(ht->ht);
  48         assert(event);
  49
  50         key.name = event->attr.name;
  51         key.filter = (struct lttng_filter_bytecode *) event->filter;
  52         key.loglevel = event->attr.loglevel;
  53         key.exclusion = event->exclusion;
  54
  55         node_ptr = cds_lfht_add_unique(ht->ht,
  56                         ht->hash_fct(event->node.key, lttng_ht_seed),
  57                         trace_ust_ht_match_event, &key, &event->node.node);
  58         assert(node_ptr == &event->node.node);
  59 }
  60
  61 /*
  62  * Disable kernel tracepoint event for a channel from the kernel session.
  63  */
  64 int event_kernel_disable_tracepoint(struct ltt_kernel_channel *kchan,
  65                 char *event_name)
  66 {
  67         int ret;
  68         struct ltt_kernel_event *kevent;
  69
  70         assert(kchan);
  71
  72         kevent = trace_kernel_get_event_by_name(event_name, kchan);
  73         if (kevent == NULL) {
  74                 ret = LTTNG_ERR_NO_EVENT;
  75                 goto error;
  76         }
  77
  78         ret = kernel_disable_event(kevent);
  79         if (ret < 0) {
  80                 ret = LTTNG_ERR_KERN_DISABLE_FAIL;
  81                 goto error;
  82         }
  83
  84         DBG("Kernel event %s disable for channel %s.",
  85                         kevent->event->name, kchan->channel->name);
  86
  87         ret = LTTNG_OK;
  88
  89 error:
  90         return ret;
  91 }
  92
  93 /*
  94  * Enable kernel system call for a channel from the kernel session.
  95  */
  96 int event_kernel_enable_syscall(struct ltt_kernel_channel *kchan,
  97                 char *syscall_name)
  98 {
  99         int ret;
 100
 101         assert(kchan);
 102
 103         ret = kernel_enable_syscall(syscall_name, kchan);
 104         if (ret < 0) {
 105                 ret = LTTNG_ERR_KERN_ENABLE_FAIL;
 106                 goto error;
 107         }
 108
 109         DBG("Kernel event %s enable for channel %s.",
 110                         syscall_name, kchan->channel->name);
 111
 112         ret = LTTNG_OK;
 113
 114 error:
 115         return ret;
 116 }
 117
 118 /*
 119  * Disable kernel system call for a channel from the kernel session.
 120  */
 121 int event_kernel_disable_syscall(struct ltt_kernel_channel *kchan,
 122                 char *syscall_name)
 123 {
 124         int ret;
 125
 126         assert(kchan);
 127
 128         ret = kernel_disable_syscall(syscall_name, kchan);
 129         if (ret < 0) {
 130                 ret = LTTNG_ERR_KERN_DISABLE_FAIL;
 131                 goto error;
 132         }
 133
 134         DBG("Kernel syscall %s disable for channel %s.",
 135                         syscall_name[0] == '\0' ? "<all>" : syscall_name,
 136                         kchan->channel->name);
 137
 138         ret = LTTNG_OK;
 139
 140 error:
 141         return ret;
 142 }
 143
 144 /*
 145  * Disable kernel tracepoint events for a channel from the kernel session.
 146  */
 147 int event_kernel_disable_all_tracepoints(struct ltt_kernel_channel *kchan)
 148 {
 149         int ret;
 150         struct ltt_kernel_event *kevent;
 151
 152         assert(kchan);
 153
 154         /* For each event in the kernel session */
 155         cds_list_for_each_entry(kevent, &kchan->events_list.head, list) {
 156                 ret = kernel_disable_event(kevent);
 157                 if (ret < 0) {
 158                         /* We continue disabling the rest */
 159                         continue;
 160                 }
 161         }
 162         ret = LTTNG_OK;
 163         return ret;
 164 }
 165
 166 /*
 167  * Disable all kernel event for a channel from the kernel session.
 168  */
 169 int event_kernel_disable_all(struct ltt_kernel_channel *kchan)
 170 {
 171         int ret;
 172
 173         assert(kchan);
 174
 175         ret = event_kernel_disable_all_tracepoints(kchan);
 176         if (ret != LTTNG_OK)
 177                 return ret;
 178         ret = event_kernel_disable_syscall(kchan, "");
 179         return ret;
 180 }
 181
 182 /*
 183  * Enable kernel tracepoint event for a channel from the kernel session.
 184  */
 185 int event_kernel_enable_tracepoint(struct ltt_kernel_channel *kchan,
 186                 struct lttng_event *event)
 187 {
 188         int ret;
 189         struct ltt_kernel_event *kevent;
 190
 191         assert(kchan);
 192         assert(event);
 193
 194         kevent = trace_kernel_get_event_by_name(event->name, kchan);
 195         if (kevent == NULL) {
 196                 ret = kernel_create_event(event, kchan);
 197                 if (ret < 0) {
 198                         switch (-ret) {
 199                         case EEXIST:
 200                                 ret = LTTNG_ERR_KERN_EVENT_EXIST;
 201                                 break;
 202                         case ENOSYS:
 203                                 ret = LTTNG_ERR_KERN_EVENT_ENOSYS;
 204                                 break;
 205                         default:
 206                                 ret = LTTNG_ERR_KERN_ENABLE_FAIL;
 207                                 break;
 208                         }
 209                         goto end;
 210                 }
 211         } else if (kevent->enabled == 0) {
 212                 ret = kernel_enable_event(kevent);
 213                 if (ret < 0) {
 214                         ret = LTTNG_ERR_KERN_ENABLE_FAIL;
 215                         goto end;
 216                 }
 217         } else {
 218                 /* At this point, the event is considered enabled */
 219                 ret = LTTNG_ERR_KERN_EVENT_EXIST;
 220                 goto end;
 221         }
 222
 223         ret = LTTNG_OK;
 224 end:
 225         return ret;
 226 }
 227
 228 /*
 229  * Enable all kernel tracepoint events of a channel of the kernel session.
 230  */
 231 int event_kernel_enable_all_tracepoints(struct ltt_kernel_channel *kchan,
 232                 int kernel_tracer_fd)
 233 {
 234         int size, i, ret;
 235         struct ltt_kernel_event *kevent;
 236         struct lttng_event *event_list = NULL;
 237
 238         assert(kchan);
 239
 240         /* For each event in the kernel session */
 241         cds_list_for_each_entry(kevent, &kchan->events_list.head, list) {
 242                 if (kevent->enabled == 0) {
 243                         ret = kernel_enable_event(kevent);
 244                         if (ret < 0) {
 245                                 /* Enable failed but still continue */
 246                                 continue;
 247                         }
 248                 }
 249         }
 250
 251         size = kernel_list_events(kernel_tracer_fd, &event_list);
 252         if (size < 0) {
 253                 ret = LTTNG_ERR_KERN_LIST_FAIL;
 254                 goto end;
 255         }
 256
 257         for (i = 0; i < size; i++) {
 258                 kevent = trace_kernel_get_event_by_name(event_list[i].name, kchan);
 259                 if (kevent == NULL) {
 260                         /* Default event type for enable all */
 261                         event_list[i].type = LTTNG_EVENT_TRACEPOINT;
 262                         /* Enable each single tracepoint event */
 263                         ret = kernel_create_event(&event_list[i], kchan);
 264                         if (ret < 0) {
 265                                 /* Ignore error here and continue */
 266                         }
 267                 }
 268         }
 269         free(event_list);
 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_syscall(kchan, "");
 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,
 317                 char *filter_expression,
 318                 struct lttng_filter_bytecode *filter)
 319 {
 320         int ret, i, size;
 321         struct lttng_ht_iter iter;
 322         struct ltt_ust_event *uevent = NULL;
 323         struct lttng_event *events = NULL;
 324
 325         assert(usess);
 326         assert(uchan);
 327
 328         rcu_read_lock();
 329
 330         /* Enable existing events */
 331         cds_lfht_for_each_entry(uchan->events->ht, &iter.iter, uevent,
 332                         node.node) {
 333                 if (uevent->enabled == 0) {
 334                         ret = ust_app_enable_event_glb(usess, uchan, uevent);
 335                         if (ret < 0) {
 336                                 continue;
 337                         }
 338                         uevent->enabled = 1;
 339                 }
 340         }
 341
 342         /* Get all UST available events */
 343         size = ust_app_list_events(&events);
 344         if (size < 0) {
 345                 ret = LTTNG_ERR_UST_LIST_FAIL;
 346                 goto error;
 347         }
 348
 349         for (i = 0; i < size; i++) {
 350                 /*
 351                  * Check if event exist and if so, continue since it was enable
 352                  * previously.
 353                  */
 354                 uevent = trace_ust_find_event(uchan->events, events[i].name, filter,
 355                                 events[i].loglevel, NULL);
 356                 if (uevent != NULL) {
 357                         ret = ust_app_enable_event_pid(usess, uchan, uevent,
 358                                         events[i].pid);
 359                         if (ret < 0) {
 360                                 if (ret != -LTTNG_UST_ERR_EXIST) {
 361                                         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 362                                         goto error;
 363                                 }
 364                         }
 365                         continue;
 366                 }
 367
 368                 /* Create ust event */
 369                 uevent = trace_ust_create_event(&events[i], filter_expression,
 370                         filter, NULL);
 371                 if (uevent == NULL) {
 372                         ret = LTTNG_ERR_FATAL;
 373                         goto error_destroy;
 374                 }
 375
 376                 /* Create event for the specific PID */
 377                 ret = ust_app_enable_event_pid(usess, uchan, uevent,
 378                                 events[i].pid);
 379                 if (ret < 0) {
 380                         if (ret == -LTTNG_UST_ERR_EXIST) {
 381                                 ret = LTTNG_ERR_UST_EVENT_EXIST;
 382                                 goto error;
 383                         } else {
 384                                 ret = LTTNG_ERR_UST_ENABLE_FAIL;
 385                                 goto error_destroy;
 386                         }
 387                 }
 388
 389                 uevent->enabled = 1;
 390                 /* Add ltt ust event to channel */
 391                 rcu_read_lock();
 392                 add_unique_ust_event(uchan->events, uevent);
 393                 rcu_read_unlock();
 394         }
 395         free(events);
 396
 397         rcu_read_unlock();
 398         return LTTNG_OK;
 399
 400 error_destroy:
 401         trace_ust_destroy_event(uevent);
 402
 403 error:
 404         free(events);
 405         rcu_read_unlock();
 406         return ret;
 407 }
 408
 409 /*
 410  * Enable UST tracepoint event for a channel from a UST session.
 411  */
 412 int event_ust_enable_tracepoint(struct ltt_ust_session *usess,
 413                 struct ltt_ust_channel *uchan, struct lttng_event *event,
 414                 char *filter_expression,
 415                 struct lttng_filter_bytecode *filter,
 416                 struct lttng_event_exclusion *exclusion)
 417 {
 418         int ret = LTTNG_OK, to_create = 0;
 419         struct ltt_ust_event *uevent;
 420
 421         assert(usess);
 422         assert(uchan);
 423         assert(event);
 424
 425         rcu_read_lock();
 426
 427         uevent = trace_ust_find_event(uchan->events, event->name, filter,
 428                         event->loglevel, exclusion);
 429         if (uevent == NULL) {
 430                 uevent = trace_ust_create_event(event, filter_expression,
 431                         filter, exclusion);
 432                 if (uevent == NULL) {
 433                         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 434                         goto error;
 435                 }
 436
 437                 /* Valid to set it after the goto error since uevent is still NULL */
 438                 to_create = 1;
 439         }
 440
 441         if (uevent->enabled) {
 442                 /* It's already enabled so everything is OK */
 443                 ret = LTTNG_ERR_UST_EVENT_ENABLED;
 444                 goto end;
 445         }
 446
 447         uevent->enabled = 1;
 448
 449         if (to_create) {
 450                 /* Create event on all UST registered apps for session */
 451                 ret = ust_app_create_event_glb(usess, uchan, uevent);
 452         } else {
 453                 /* Enable event on all UST registered apps for session */
 454                 ret = ust_app_enable_event_glb(usess, uchan, uevent);
 455         }
 456
 457         if (ret < 0) {
 458                 if (ret == -LTTNG_UST_ERR_EXIST) {
 459                         ret = LTTNG_ERR_UST_EVENT_EXIST;
 460                         goto end;
 461                 } else {
 462                         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 463                         goto error;
 464                 }
 465         }
 466
 467         if (to_create) {
 468                 /* Add ltt ust event to channel */
 469                 add_unique_ust_event(uchan->events, uevent);
 470         }
 471
 472         DBG("Event UST %s %s in channel %s", uevent->attr.name,
 473                         to_create ? "created" : "enabled", uchan->name);
 474
 475         ret = LTTNG_OK;
 476
 477 end:
 478         rcu_read_unlock();
 479         return ret;
 480
 481 error:
 482         /*
 483          * Only destroy event on creation time (not enabling time) because if the
 484          * event is found in the channel (to_create == 0), it means that at some
 485          * point the enable_event worked and it's thus valid to keep it alive.
 486          * Destroying it also implies that we also destroy it's shadow copy to sync
 487          * everyone up.
 488          */
 489         if (to_create) {
 490                 /* In this code path, the uevent was not added to the hash table */
 491                 trace_ust_destroy_event(uevent);
 492         }
 493         rcu_read_unlock();
 494         return ret;
 495 }
 496
 497 /*
 498  * Disable UST tracepoint of a channel from a UST session.
 499  */
 500 int event_ust_disable_tracepoint(struct ltt_ust_session *usess,
 501                 struct ltt_ust_channel *uchan, char *event_name)
 502 {
 503         int ret;
 504         struct ltt_ust_event *uevent;
 505         struct lttng_ht_node_str *node;
 506         struct lttng_ht_iter iter;
 507         struct lttng_ht *ht;
 508
 509         assert(usess);
 510         assert(uchan);
 511         assert(event_name);
 512
 513         ht = uchan->events;
 514
 515         rcu_read_lock();
 516
 517         /*
 518          * We use a custom lookup since we need the iterator for the next_duplicate
 519          * call in the do while loop below.
 520          */
 521         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) event_name, lttng_ht_seed),
 522                         trace_ust_ht_match_event_by_name, event_name, &iter.iter);
 523         node = lttng_ht_iter_get_node_str(&iter);
 524         if (node == NULL) {
 525                 DBG2("Trace UST event NOT found by name %s", event_name);
 526                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 527                 goto error;
 528         }
 529
 530         do {
 531                 uevent = caa_container_of(node, struct ltt_ust_event, node);
 532                 assert(uevent);
 533
 534                 if (uevent->enabled == 0) {
 535                         /* It's already disabled so everything is OK */
 536                         goto next;
 537                 }
 538
 539                 ret = ust_app_disable_event_glb(usess, uchan, uevent);
 540                 if (ret < 0 && ret != -LTTNG_UST_ERR_EXIST) {
 541                         ret = LTTNG_ERR_UST_DISABLE_FAIL;
 542                         goto error;
 543                 }
 544                 uevent->enabled = 0;
 545
 546                 DBG2("Event UST %s disabled in channel %s", uevent->attr.name,
 547                                 uchan->name);
 548
 549 next:
 550                 /* Get next duplicate event by name. */
 551                 cds_lfht_next_duplicate(ht->ht, trace_ust_ht_match_event_by_name,
 552                                 event_name, &iter.iter);
 553                 node = lttng_ht_iter_get_node_str(&iter);
 554         } while (node);
 555
 556         ret = LTTNG_OK;
 557
 558 error:
 559         rcu_read_unlock();
 560         return ret;
 561 }
 562
 563 /*
 564  * Disable all UST tracepoints for a channel from a UST session.
 565  */
 566 int event_ust_disable_all_tracepoints(struct ltt_ust_session *usess,
 567                 struct ltt_ust_channel *uchan)
 568 {
 569         int ret, i, size;
 570         struct lttng_ht_iter iter;
 571         struct ltt_ust_event *uevent = NULL;
 572         struct lttng_event *events = NULL;
 573
 574         assert(usess);
 575         assert(uchan);
 576
 577         rcu_read_lock();
 578
 579         /* Disabling existing events */
 580         cds_lfht_for_each_entry(uchan->events->ht, &iter.iter, uevent,
 581                         node.node) {
 582                 if (uevent->enabled == 1) {
 583                         ret = event_ust_disable_tracepoint(usess, uchan,
 584                                         uevent->attr.name);
 585                         if (ret < 0) {
 586                                 continue;
 587                         }
 588                 }
 589         }
 590
 591         /* Get all UST available events */
 592         size = ust_app_list_events(&events);
 593         if (size < 0) {
 594                 ret = LTTNG_ERR_UST_LIST_FAIL;
 595                 goto error;
 596         }
 597
 598         for (i = 0; i < size; i++) {
 599                 ret = event_ust_disable_tracepoint(usess, uchan,
 600                                 events[i].name);
 601                 if (ret != LTTNG_OK) {
 602                         /* Continue to disable the rest... */
 603                         continue;
 604                 }
 605         }
 606         free(events);
 607
 608         rcu_read_unlock();
 609         return LTTNG_OK;
 610
 611 error:
 612         free(events);
 613         rcu_read_unlock();
 614         return ret;
 615 }
 616
 617 /*
 618  * Enable all agent event for a given UST session.
 619  *
 620  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 621  */
 622 int event_agent_enable_all(struct ltt_ust_session *usess,
 623                 struct agent *agt, struct lttng_event *event,
 624                 struct lttng_filter_bytecode *filter)
 625 {
 626         int ret;
 627         struct agent_event *aevent;
 628         struct lttng_ht_iter iter;
 629
 630         assert(usess);
 631
 632         DBG("Event agent enabling ALL events for session %" PRIu64, usess->id);
 633
 634         /* Enable event on agent application through TCP socket. */
 635         ret = event_agent_enable(usess, agt, event, filter);
 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(agt->events->ht, &iter.iter, aevent,
 643                         node.node) {
 644                 aevent->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 agent event for a given UST session.
 656  *
 657  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 658  */
 659 int event_agent_enable(struct ltt_ust_session *usess,
 660                 struct agent *agt, struct lttng_event *event,
 661                 struct lttng_filter_bytecode *filter)
 662 {
 663         int ret, created = 0;
 664         struct agent_event *aevent;
 665
 666         assert(usess);
 667         assert(event);
 668         assert(agt);
 669
 670         DBG("Event agent enabling %s for session %" PRIu64 " with loglevel type %d "
 671                         "and loglevel %d", event->name, usess->id, event->loglevel_type,
 672                         event->loglevel);
 673
 674         aevent = agent_find_event(event->name, event->loglevel, agt);
 675         if (!aevent) {
 676                 aevent = agent_create_event(event->name, filter);
 677                 if (!aevent) {
 678                         ret = LTTNG_ERR_NOMEM;
 679                         goto error;
 680                 }
 681                 aevent->loglevel = event->loglevel;
 682                 aevent->loglevel_type = event->loglevel_type;
 683                 created = 1;
 684         }
 685
 686         /* Already enabled? */
 687         if (aevent->enabled) {
 688                 goto end;
 689         }
 690
 691         ret = agent_enable_event(aevent, agt->domain);
 692         if (ret != LTTNG_OK) {
 693                 goto error;
 694         }
 695
 696         /* If the event was created prior to the enable, add it to the domain. */
 697         if (created) {
 698                 agent_add_event(aevent, agt);
 699         }
 700
 701 end:
 702         return LTTNG_OK;
 703
 704 error:
 705         if (created) {
 706                 agent_destroy_event(aevent);
 707         }
 708         return ret;
 709 }
 710
 711 /*
 712  * Return the agent default event name to use by testing if the process is root
 713  * or not. Return NULL on error.
 714  */
 715 const char *event_get_default_agent_ust_name(enum lttng_domain_type domain)
 716 {
 717         const char *default_event_name = NULL;
 718
 719         switch (domain) {
 720         case LTTNG_DOMAIN_LOG4J:
 721                 if (is_root) {
 722                         default_event_name = DEFAULT_SYS_LOG4J_EVENT_NAME;
 723                 } else {
 724                         default_event_name = DEFAULT_USER_LOG4J_EVENT_NAME;
 725                 }
 726                 break;
 727         case LTTNG_DOMAIN_JUL:
 728                 if (is_root) {
 729                         default_event_name = DEFAULT_SYS_JUL_EVENT_NAME;
 730                 } else {
 731                         default_event_name = DEFAULT_USER_JUL_EVENT_NAME;
 732                 }
 733                 break;
 734         case LTTNG_DOMAIN_PYTHON:
 735                 default_event_name = DEFAULT_USER_PYTHON_EVENT_NAME;
 736                 break;
 737         default:
 738                 assert(0);
 739         }
 740
 741         return default_event_name;
 742 }
 743
 744 /*
 745  * Disable a single agent event for a given UST session.
 746  *
 747  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 748  */
 749 int event_agent_disable(struct ltt_ust_session *usess, struct agent *agt,
 750                 char *event_name)
 751 {
 752         int ret;
 753         struct agent_event *aevent;
 754         struct ltt_ust_event *uevent = NULL;
 755         struct ltt_ust_channel *uchan = NULL;
 756         const char *ust_event_name, *ust_channel_name;
 757
 758         assert(agt);
 759         assert(usess);
 760         assert(event_name);
 761
 762         DBG("Event agent disabling %s for session %" PRIu64, event_name, usess->id);
 763
 764         aevent = agent_find_event_by_name(event_name, agt);
 765         if (!aevent) {
 766                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 767                 goto error;
 768         }
 769
 770         /* Already disabled? */
 771         if (!aevent->enabled) {
 772                 goto end;
 773         }
 774
 775         if (agt->domain == LTTNG_DOMAIN_JUL) {
 776                 ust_channel_name = DEFAULT_JUL_CHANNEL_NAME;
 777         } else if (agt->domain == LTTNG_DOMAIN_LOG4J) {
 778                 ust_channel_name = DEFAULT_LOG4J_CHANNEL_NAME;
 779         } else if (agt->domain == LTTNG_DOMAIN_PYTHON) {
 780                 ust_channel_name = DEFAULT_PYTHON_CHANNEL_NAME;
 781         } else {
 782                 ret = LTTNG_ERR_INVALID;
 783                 goto error;
 784         }
 785
 786         /*
 787          * Disable it on the UST side. First get the channel reference then find
 788          * the event and finally disable it.
 789          */
 790         uchan = trace_ust_find_channel_by_name(usess->domain_global.channels,
 791                         (char *) ust_channel_name);
 792         if (!uchan) {
 793                 ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
 794                 goto error;
 795         }
 796
 797         ust_event_name = event_get_default_agent_ust_name(agt->domain);
 798         if (!ust_event_name) {
 799                 ret = LTTNG_ERR_FATAL;
 800                 goto error;
 801         }
 802
 803         /*
 804          * The loglevel is hardcoded with 0 here since the agent ust event is set
 805          * with the loglevel type to ALL thus the loglevel stays 0. The event's
 806          * filter is the one handling the loglevel for agent.
 807          */
 808         uevent = trace_ust_find_event(uchan->events, (char *) ust_event_name,
 809                         aevent->filter, 0, NULL);
 810         /* If the agent event exists, it must be available on the UST side. */
 811         assert(uevent);
 812
 813         ret = ust_app_disable_event_glb(usess, uchan, uevent);
 814         if (ret < 0 && ret != -LTTNG_UST_ERR_EXIST) {
 815                 ret = LTTNG_ERR_UST_DISABLE_FAIL;
 816                 goto error;
 817         }
 818
 819         /*
 820          * Flag event that it's disabled so the shadow copy on the ust app side
 821          * will disable it if an application shows up.
 822          */
 823         uevent->enabled = 0;
 824
 825         ret = agent_disable_event(aevent, agt->domain);
 826         if (ret != LTTNG_OK) {
 827                 goto error;
 828         }
 829
 830 end:
 831         return LTTNG_OK;
 832
 833 error:
 834         return ret;
 835 }
 836 /*
 837  * Disable all agent event for a given UST session.
 838  *
 839  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 840  */
 841 int event_agent_disable_all(struct ltt_ust_session *usess,
 842                 struct agent *agt)
 843 {
 844         int ret;
 845         struct agent_event *aevent;
 846         struct lttng_ht_iter iter;
 847
 848         assert(agt);
 849         assert(usess);
 850
 851         /*
 852          * Disable event on agent application. Continue to disable all other events
 853          * if the * event is not found.
 854          */
 855         ret = event_agent_disable(usess, agt, "*");
 856         if (ret != LTTNG_OK && ret != LTTNG_ERR_UST_EVENT_NOT_FOUND) {
 857                 goto error;
 858         }
 859
 860         /* Flag every event that they are now enabled. */
 861         rcu_read_lock();
 862         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, aevent,
 863                         node.node) {
 864                 if (!aevent->enabled) {
 865                         continue;
 866                 }
 867
 868                 ret = event_agent_disable(usess, agt, aevent->name);
 869                 if (ret != LTTNG_OK) {
 870                         rcu_read_unlock();
 871                         goto error;
 872                 }
 873         }
 874         rcu_read_unlock();
 875
 876         ret = LTTNG_OK;
 877
 878 error:
 879         return ret;
 880 }