liblttng-ust/lttng-events.c

   1 /*
   2  * SPDX-License-Identifier: LGPL-2.1-only
   3  *
   4  * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * Holds LTTng per-session event registry.
   7  */
   8
   9 #define _LGPL_SOURCE
  10 #include <stdio.h>
  11 #include <assert.h>
  12 #include <errno.h>
  13 #include <limits.h>
  14 #include <pthread.h>
  15 #include <sys/shm.h>
  16 #include <sys/ipc.h>
  17 #include <stdint.h>
  18 #include <stddef.h>
  19 #include <inttypes.h>
  20 #include <time.h>
  21 #include <stdbool.h>
  22 #include <unistd.h>
  23 #include <dlfcn.h>
  24 #include <lttng/ust-endian.h>
  25
  26 #include <urcu/arch.h>
  27 #include <urcu/compiler.h>
  28 #include <urcu/hlist.h>
  29 #include <urcu/list.h>
  30 #include <urcu/uatomic.h>
  31
  32 #include <lttng/tracepoint.h>
  33 #include <lttng/ust-events.h>
  34
  35 #include <usterr-signal-safe.h>
  36 #include <ust-helper.h>
  37 #include <lttng/ust-ctl.h>
  38 #include <ust-comm.h>
  39 #include <ust-fd.h>
  40 #include <ust-dynamic-type.h>
  41 #include <ust-context-provider.h>
  42 #include "error.h"
  43 #include "compat.h"
  44 #include "lttng-ust-uuid.h"
  45
  46 #include "tracepoint-internal.h"
  47 #include "string-utils.h"
  48 #include "lttng-bytecode.h"
  49 #include "lttng-tracer.h"
  50 #include "lttng-tracer-core.h"
  51 #include "lttng-ust-statedump.h"
  52 #include "context-internal.h"
  53 #include "ust-events-internal.h"
  54 #include "wait.h"
  55 #include "../libringbuffer/shm.h"
  56 #include "../libcounter/counter.h"
  57 #include "jhash.h"
  58 #include <lttng/ust-abi.h>
  59
  60 /*
  61  * All operations within this file are called by the communication
  62  * thread, under ust_lock protection.
  63  */
  64
  65 static CDS_LIST_HEAD(sessions);
  66 static CDS_LIST_HEAD(event_notifier_groups);
  67
  68 struct cds_list_head *lttng_get_sessions(void)
  69 {
  70         return &sessions;
  71 }
  72
  73 static void _lttng_event_destroy(struct lttng_event *event);
  74 static void _lttng_event_notifier_destroy(
  75                 struct lttng_event_notifier *event_notifier);
  76 static void _lttng_enum_destroy(struct lttng_enum *_enum);
  77
  78 static
  79 void lttng_session_lazy_sync_event_enablers(struct lttng_session *session);
  80 static
  81 void lttng_session_sync_event_enablers(struct lttng_session *session);
  82 static
  83 void lttng_event_notifier_group_sync_enablers(
  84                 struct lttng_event_notifier_group *event_notifier_group);
  85 static
  86 void lttng_enabler_destroy(struct lttng_enabler *enabler);
  87
  88 /*
  89  * Called with ust lock held.
  90  */
  91 int lttng_session_active(void)
  92 {
  93         struct lttng_session *iter;
  94
  95         cds_list_for_each_entry(iter, &sessions, node) {
  96                 if (iter->active)
  97                         return 1;
  98         }
  99         return 0;
 100 }
 101
 102 static
 103 int lttng_loglevel_match(int loglevel,
 104                 unsigned int has_loglevel,
 105                 enum lttng_ust_loglevel_type req_type,
 106                 int req_loglevel)
 107 {
 108         if (!has_loglevel)
 109                 loglevel = TRACE_DEFAULT;
 110         switch (req_type) {
 111         case LTTNG_UST_LOGLEVEL_RANGE:
 112                 if (loglevel <= req_loglevel
 113                                 || (req_loglevel == -1 && loglevel <= TRACE_DEBUG))
 114                         return 1;
 115                 else
 116                         return 0;
 117         case LTTNG_UST_LOGLEVEL_SINGLE:
 118                 if (loglevel == req_loglevel
 119                                 || (req_loglevel == -1 && loglevel <= TRACE_DEBUG))
 120                         return 1;
 121                 else
 122                         return 0;
 123         case LTTNG_UST_LOGLEVEL_ALL:
 124         default:
 125                 if (loglevel <= TRACE_DEBUG)
 126                         return 1;
 127                 else
 128                         return 0;
 129         }
 130 }
 131
 132 struct lttng_session *lttng_session_create(void)
 133 {
 134         struct lttng_session *session;
 135         int i;
 136
 137         session = zmalloc(sizeof(struct lttng_session));
 138         if (!session)
 139                 return NULL;
 140         if (lttng_context_init_all(&session->ctx)) {
 141                 free(session);
 142                 return NULL;
 143         }
 144         CDS_INIT_LIST_HEAD(&session->chan_head);
 145         CDS_INIT_LIST_HEAD(&session->events_head);
 146         CDS_INIT_LIST_HEAD(&session->enums_head);
 147         CDS_INIT_LIST_HEAD(&session->enablers_head);
 148         for (i = 0; i < LTTNG_UST_EVENT_HT_SIZE; i++)
 149                 CDS_INIT_HLIST_HEAD(&session->events_ht.table[i]);
 150         for (i = 0; i < LTTNG_UST_ENUM_HT_SIZE; i++)
 151                 CDS_INIT_HLIST_HEAD(&session->enums_ht.table[i]);
 152         cds_list_add(&session->node, &sessions);
 153         return session;
 154 }
 155
 156 struct lttng_counter *lttng_ust_counter_create(
 157                 const char *counter_transport_name,
 158                 size_t number_dimensions, const struct lttng_counter_dimension *dimensions)
 159 {
 160         struct lttng_counter_transport *counter_transport = NULL;
 161         struct lttng_counter *counter = NULL;
 162
 163         counter_transport = lttng_counter_transport_find(counter_transport_name);
 164         if (!counter_transport)
 165                 goto notransport;
 166         counter = zmalloc(sizeof(struct lttng_counter));
 167         if (!counter)
 168                 goto nomem;
 169
 170         counter->ops = &counter_transport->ops;
 171         counter->transport = counter_transport;
 172
 173         counter->counter = counter->ops->counter_create(
 174                         number_dimensions, dimensions, 0,
 175                         -1, 0, NULL, false);
 176         if (!counter->counter) {
 177                 goto create_error;
 178         }
 179
 180         return counter;
 181
 182 create_error:
 183         free(counter);
 184 nomem:
 185 notransport:
 186         return NULL;
 187 }
 188
 189 static
 190 void lttng_ust_counter_destroy(struct lttng_counter *counter)
 191 {
 192         counter->ops->counter_destroy(counter->counter);
 193         free(counter);
 194 }
 195
 196 struct lttng_event_notifier_group *lttng_event_notifier_group_create(void)
 197 {
 198         struct lttng_event_notifier_group *event_notifier_group;
 199         int i;
 200
 201         event_notifier_group = zmalloc(sizeof(struct lttng_event_notifier_group));
 202         if (!event_notifier_group)
 203                 return NULL;
 204
 205         /* Add all contexts. */
 206         if (lttng_context_init_all(&event_notifier_group->ctx)) {
 207                 free(event_notifier_group);
 208                 return NULL;
 209         }
 210
 211         CDS_INIT_LIST_HEAD(&event_notifier_group->enablers_head);
 212         CDS_INIT_LIST_HEAD(&event_notifier_group->event_notifiers_head);
 213         for (i = 0; i < LTTNG_UST_EVENT_NOTIFIER_HT_SIZE; i++)
 214                 CDS_INIT_HLIST_HEAD(&event_notifier_group->event_notifiers_ht.table[i]);
 215
 216         cds_list_add(&event_notifier_group->node, &event_notifier_groups);
 217
 218         return event_notifier_group;
 219 }
 220
 221 /*
 222  * Only used internally at session destruction.
 223  */
 224 static
 225 void _lttng_channel_unmap(struct lttng_channel *lttng_chan)
 226 {
 227         struct channel *chan;
 228         struct lttng_ust_shm_handle *handle;
 229
 230         cds_list_del(&lttng_chan->node);
 231         lttng_destroy_context(lttng_chan->ctx);
 232         chan = lttng_chan->chan;
 233         handle = lttng_chan->handle;
 234         /*
 235          * note: lttng_chan is private data contained within handle. It
 236          * will be freed along with the handle.
 237          */
 238         channel_destroy(chan, handle, 0);
 239 }
 240
 241 static
 242 void register_event(struct lttng_event *event)
 243 {
 244         int ret;
 245         const struct lttng_event_desc *desc;
 246
 247         assert(event->priv->registered == 0);
 248         desc = event->priv->desc;
 249         ret = __tracepoint_probe_register_queue_release(desc->name,
 250                         desc->probe_callback,
 251                         event, desc->signature);
 252         WARN_ON_ONCE(ret);
 253         if (!ret)
 254                 event->priv->registered = 1;
 255 }
 256
 257 static
 258 void register_event_notifier(struct lttng_event_notifier *event_notifier)
 259 {
 260         int ret;
 261         const struct lttng_event_desc *desc;
 262
 263         assert(event_notifier->registered == 0);
 264         desc = event_notifier->desc;
 265         ret = __tracepoint_probe_register_queue_release(desc->name,
 266                 desc->u.ext.event_notifier_callback, event_notifier, desc->signature);
 267         WARN_ON_ONCE(ret);
 268         if (!ret)
 269                 event_notifier->registered = 1;
 270 }
 271
 272 static
 273 void unregister_event(struct lttng_event *event)
 274 {
 275         int ret;
 276         const struct lttng_event_desc *desc;
 277
 278         assert(event->priv->registered == 1);
 279         desc = event->priv->desc;
 280         ret = __tracepoint_probe_unregister_queue_release(desc->name,
 281                         desc->probe_callback,
 282                         event);
 283         WARN_ON_ONCE(ret);
 284         if (!ret)
 285                 event->priv->registered = 0;
 286 }
 287
 288 static
 289 void unregister_event_notifier(struct lttng_event_notifier *event_notifier)
 290 {
 291         int ret;
 292         const struct lttng_event_desc *desc;
 293
 294         assert(event_notifier->registered == 1);
 295         desc = event_notifier->desc;
 296         ret = __tracepoint_probe_unregister_queue_release(desc->name,
 297                 desc->u.ext.event_notifier_callback, event_notifier);
 298         WARN_ON_ONCE(ret);
 299         if (!ret)
 300                 event_notifier->registered = 0;
 301 }
 302
 303 /*
 304  * Only used internally at session destruction.
 305  */
 306 static
 307 void _lttng_event_unregister(struct lttng_event *event)
 308 {
 309         if (event->priv->registered)
 310                 unregister_event(event);
 311 }
 312
 313 /*
 314  * Only used internally at session destruction.
 315  */
 316 static
 317 void _lttng_event_notifier_unregister(struct lttng_event_notifier *event_notifier)
 318 {
 319         if (event_notifier->registered)
 320                 unregister_event_notifier(event_notifier);
 321 }
 322
 323 void lttng_session_destroy(struct lttng_session *session)
 324 {
 325         struct lttng_channel *chan, *tmpchan;
 326         struct lttng_ust_event_private *event_priv, *tmpevent_priv;
 327         struct lttng_enum *_enum, *tmp_enum;
 328         struct lttng_event_enabler *event_enabler, *event_tmpenabler;
 329
 330         CMM_ACCESS_ONCE(session->active) = 0;
 331         cds_list_for_each_entry(event_priv, &session->events_head, node) {
 332                 _lttng_event_unregister(event_priv->pub);
 333         }
 334         lttng_ust_urcu_synchronize_rcu();       /* Wait for in-flight events to complete */
 335         __tracepoint_probe_prune_release_queue();
 336         cds_list_for_each_entry_safe(event_enabler, event_tmpenabler,
 337                         &session->enablers_head, node)
 338                 lttng_event_enabler_destroy(event_enabler);
 339         cds_list_for_each_entry_safe(event_priv, tmpevent_priv,
 340                         &session->events_head, node)
 341                 _lttng_event_destroy(event_priv->pub);
 342         cds_list_for_each_entry_safe(_enum, tmp_enum,
 343                         &session->enums_head, node)
 344                 _lttng_enum_destroy(_enum);
 345         cds_list_for_each_entry_safe(chan, tmpchan, &session->chan_head, node)
 346                 _lttng_channel_unmap(chan);
 347         cds_list_del(&session->node);
 348         lttng_destroy_context(session->ctx);
 349         free(session);
 350 }
 351
 352 void lttng_event_notifier_group_destroy(
 353                 struct lttng_event_notifier_group *event_notifier_group)
 354 {
 355         int close_ret;
 356         struct lttng_event_notifier_enabler *notifier_enabler, *tmpnotifier_enabler;
 357         struct lttng_event_notifier *notifier, *tmpnotifier;
 358
 359         if (!event_notifier_group) {
 360                 return;
 361         }
 362
 363         cds_list_for_each_entry(notifier,
 364                         &event_notifier_group->event_notifiers_head, node)
 365                 _lttng_event_notifier_unregister(notifier);
 366
 367         lttng_ust_urcu_synchronize_rcu();
 368
 369         cds_list_for_each_entry_safe(notifier_enabler, tmpnotifier_enabler,
 370                         &event_notifier_group->enablers_head, node)
 371                 lttng_event_notifier_enabler_destroy(notifier_enabler);
 372
 373         cds_list_for_each_entry_safe(notifier, tmpnotifier,
 374                         &event_notifier_group->event_notifiers_head, node)
 375                 _lttng_event_notifier_destroy(notifier);
 376
 377         if (event_notifier_group->error_counter)
 378                 lttng_ust_counter_destroy(event_notifier_group->error_counter);
 379
 380         /* Close the notification fd to the listener of event_notifiers. */
 381
 382         lttng_ust_lock_fd_tracker();
 383         close_ret = close(event_notifier_group->notification_fd);
 384         if (!close_ret) {
 385                 lttng_ust_delete_fd_from_tracker(
 386                                 event_notifier_group->notification_fd);
 387         } else {
 388                 PERROR("close");
 389                 abort();
 390         }
 391         lttng_ust_unlock_fd_tracker();
 392
 393         cds_list_del(&event_notifier_group->node);
 394
 395         free(event_notifier_group);
 396 }
 397
 398 static
 399 void lttng_enabler_destroy(struct lttng_enabler *enabler)
 400 {
 401         struct lttng_ust_bytecode_node *filter_node, *tmp_filter_node;
 402         struct lttng_ust_excluder_node *excluder_node, *tmp_excluder_node;
 403
 404         if (!enabler) {
 405                 return;
 406         }
 407
 408         /* Destroy filter bytecode */
 409         cds_list_for_each_entry_safe(filter_node, tmp_filter_node,
 410                         &enabler->filter_bytecode_head, node) {
 411                 free(filter_node);
 412         }
 413
 414         /* Destroy excluders */
 415         cds_list_for_each_entry_safe(excluder_node, tmp_excluder_node,
 416                         &enabler->excluder_head, node) {
 417                 free(excluder_node);
 418         }
 419 }
 420
 421  void lttng_event_notifier_enabler_destroy(struct lttng_event_notifier_enabler *event_notifier_enabler)
 422 {
 423         if (!event_notifier_enabler) {
 424                 return;
 425         }
 426
 427         cds_list_del(&event_notifier_enabler->node);
 428
 429         lttng_enabler_destroy(lttng_event_notifier_enabler_as_enabler(event_notifier_enabler));
 430
 431         free(event_notifier_enabler);
 432 }
 433
 434 static
 435 int lttng_enum_create(const struct lttng_enum_desc *desc,
 436                 struct lttng_session *session)
 437 {
 438         const char *enum_name = desc->name;
 439         struct lttng_enum *_enum;
 440         struct cds_hlist_head *head;
 441         int ret = 0;
 442         size_t name_len = strlen(enum_name);
 443         uint32_t hash;
 444         int notify_socket;
 445
 446         /* Check if this enum is already registered for this session. */
 447         hash = jhash(enum_name, name_len, 0);
 448         head = &session->enums_ht.table[hash & (LTTNG_UST_ENUM_HT_SIZE - 1)];
 449
 450         _enum = lttng_ust_enum_get_from_desc(session, desc);
 451         if (_enum) {
 452                 ret = -EEXIST;
 453                 goto exist;
 454         }
 455
 456         notify_socket = lttng_get_notify_socket(session->owner);
 457         if (notify_socket < 0) {
 458                 ret = notify_socket;
 459                 goto socket_error;
 460         }
 461
 462         _enum = zmalloc(sizeof(*_enum));
 463         if (!_enum) {
 464                 ret = -ENOMEM;
 465                 goto cache_error;
 466         }
 467         _enum->session = session;
 468         _enum->desc = desc;
 469
 470         ret = ustcomm_register_enum(notify_socket,
 471                 session->objd,
 472                 enum_name,
 473                 desc->nr_entries,
 474                 desc->entries,
 475                 &_enum->id);
 476         if (ret < 0) {
 477                 DBG("Error (%d) registering enumeration to sessiond", ret);
 478                 goto sessiond_register_error;
 479         }
 480         cds_list_add(&_enum->node, &session->enums_head);
 481         cds_hlist_add_head(&_enum->hlist, head);
 482         return 0;
 483
 484 sessiond_register_error:
 485         free(_enum);
 486 cache_error:
 487 socket_error:
 488 exist:
 489         return ret;
 490 }
 491
 492 static
 493 int lttng_create_enum_check(const struct lttng_type *type,
 494                 struct lttng_session *session)
 495 {
 496         switch (type->atype) {
 497         case atype_enum:
 498         {
 499                 const struct lttng_enum_desc *enum_desc;
 500                 int ret;
 501
 502                 enum_desc = type->u.legacy.basic.enumeration.desc;
 503                 ret = lttng_enum_create(enum_desc, session);
 504                 if (ret && ret != -EEXIST) {
 505                         DBG("Unable to create enum error: (%d)", ret);
 506                         return ret;
 507                 }
 508                 break;
 509         }
 510         case atype_enum_nestable:
 511         {
 512                 const struct lttng_enum_desc *enum_desc;
 513                 int ret;
 514
 515                 enum_desc = type->u.enum_nestable.desc;
 516                 ret = lttng_enum_create(enum_desc, session);
 517                 if (ret && ret != -EEXIST) {
 518                         DBG("Unable to create enum error: (%d)", ret);
 519                         return ret;
 520                 }
 521                 break;
 522         }
 523         case atype_dynamic:
 524         {
 525                 const struct lttng_event_field *tag_field_generic;
 526                 const struct lttng_enum_desc *enum_desc;
 527                 int ret;
 528
 529                 tag_field_generic = lttng_ust_dynamic_type_tag_field();
 530                 enum_desc = tag_field_generic->type.u.enum_nestable.desc;
 531                 ret = lttng_enum_create(enum_desc, session);
 532                 if (ret && ret != -EEXIST) {
 533                         DBG("Unable to create enum error: (%d)", ret);
 534                         return ret;
 535                 }
 536                 break;
 537         }
 538         default:
 539                 /* TODO: nested types when they become supported. */
 540                 break;
 541         }
 542         return 0;
 543 }
 544
 545 static
 546 int lttng_create_all_event_enums(size_t nr_fields,
 547                 const struct lttng_event_field *event_fields,
 548                 struct lttng_session *session)
 549 {
 550         size_t i;
 551         int ret;
 552
 553         /* For each field, ensure enum is part of the session. */
 554         for (i = 0; i < nr_fields; i++) {
 555                 const struct lttng_type *type = &event_fields[i].type;
 556
 557                 ret = lttng_create_enum_check(type, session);
 558                 if (ret)
 559                         return ret;
 560         }
 561         return 0;
 562 }
 563
 564 static
 565 int lttng_create_all_ctx_enums(size_t nr_fields,
 566                 const struct lttng_ctx_field *ctx_fields,
 567                 struct lttng_session *session)
 568 {
 569         size_t i;
 570         int ret;
 571
 572         /* For each field, ensure enum is part of the session. */
 573         for (i = 0; i < nr_fields; i++) {
 574                 const struct lttng_type *type = &ctx_fields[i].event_field.type;
 575
 576                 ret = lttng_create_enum_check(type, session);
 577                 if (ret)
 578                         return ret;
 579         }
 580         return 0;
 581 }
 582
 583 /*
 584  * Ensure that a state-dump will be performed for this session at the end
 585  * of the current handle_message().
 586  */
 587 int lttng_session_statedump(struct lttng_session *session)
 588 {
 589         session->statedump_pending = 1;
 590         lttng_ust_sockinfo_session_enabled(session->owner);
 591         return 0;
 592 }
 593
 594 int lttng_session_enable(struct lttng_session *session)
 595 {
 596         int ret = 0;
 597         struct lttng_channel *chan;
 598         int notify_socket;
 599
 600         if (session->active) {
 601                 ret = -EBUSY;
 602                 goto end;
 603         }
 604
 605         notify_socket = lttng_get_notify_socket(session->owner);
 606         if (notify_socket < 0)
 607                 return notify_socket;
 608
 609         /* Set transient enabler state to "enabled" */
 610         session->tstate = 1;
 611
 612         /* We need to sync enablers with session before activation. */
 613         lttng_session_sync_event_enablers(session);
 614
 615         /*
 616          * Snapshot the number of events per channel to know the type of header
 617          * we need to use.
 618          */
 619         cds_list_for_each_entry(chan, &session->chan_head, node) {
 620                 const struct lttng_ctx *ctx;
 621                 const struct lttng_ctx_field *fields = NULL;
 622                 size_t nr_fields = 0;
 623                 uint32_t chan_id;
 624
 625                 /* don't change it if session stop/restart */
 626                 if (chan->header_type)
 627                         continue;
 628                 ctx = chan->ctx;
 629                 if (ctx) {
 630                         nr_fields = ctx->nr_fields;
 631                         fields = ctx->fields;
 632                         ret = lttng_create_all_ctx_enums(nr_fields, fields,
 633                                 session);
 634                         if (ret < 0) {
 635                                 DBG("Error (%d) adding enum to session", ret);
 636                                 return ret;
 637                         }
 638                 }
 639                 ret = ustcomm_register_channel(notify_socket,
 640                         session,
 641                         session->objd,
 642                         chan->objd,
 643                         nr_fields,
 644                         fields,
 645                         &chan_id,
 646                         &chan->header_type);
 647                 if (ret) {
 648                         DBG("Error (%d) registering channel to sessiond", ret);
 649                         return ret;
 650                 }
 651                 if (chan_id != chan->id) {
 652                         DBG("Error: channel registration id (%u) does not match id assigned at creation (%u)",
 653                                 chan_id, chan->id);
 654                         return -EINVAL;
 655                 }
 656         }
 657
 658         /* Set atomically the state to "active" */
 659         CMM_ACCESS_ONCE(session->active) = 1;
 660         CMM_ACCESS_ONCE(session->been_active) = 1;
 661
 662         ret = lttng_session_statedump(session);
 663         if (ret)
 664                 return ret;
 665 end:
 666         return ret;
 667 }
 668
 669 int lttng_session_disable(struct lttng_session *session)
 670 {
 671         int ret = 0;
 672
 673         if (!session->active) {
 674                 ret = -EBUSY;
 675                 goto end;
 676         }
 677         /* Set atomically the state to "inactive" */
 678         CMM_ACCESS_ONCE(session->active) = 0;
 679
 680         /* Set transient enabler state to "disabled" */
 681         session->tstate = 0;
 682         lttng_session_sync_event_enablers(session);
 683 end:
 684         return ret;
 685 }
 686
 687 int lttng_channel_enable(struct lttng_channel *channel)
 688 {
 689         int ret = 0;
 690
 691         if (channel->enabled) {
 692                 ret = -EBUSY;
 693                 goto end;
 694         }
 695         /* Set transient enabler state to "enabled" */
 696         channel->tstate = 1;
 697         lttng_session_sync_event_enablers(channel->session);
 698         /* Set atomically the state to "enabled" */
 699         CMM_ACCESS_ONCE(channel->enabled) = 1;
 700 end:
 701         return ret;
 702 }
 703
 704 int lttng_channel_disable(struct lttng_channel *channel)
 705 {
 706         int ret = 0;
 707
 708         if (!channel->enabled) {
 709                 ret = -EBUSY;
 710                 goto end;
 711         }
 712         /* Set atomically the state to "disabled" */
 713         CMM_ACCESS_ONCE(channel->enabled) = 0;
 714         /* Set transient enabler state to "enabled" */
 715         channel->tstate = 0;
 716         lttng_session_sync_event_enablers(channel->session);
 717 end:
 718         return ret;
 719 }
 720
 721 static inline
 722 struct cds_hlist_head *borrow_hash_table_bucket(
 723                 struct cds_hlist_head *hash_table,
 724                 unsigned int hash_table_size,
 725                 const struct lttng_event_desc *desc)
 726 {
 727         const char *event_name;
 728         size_t name_len;
 729         uint32_t hash;
 730
 731         event_name = desc->name;
 732         name_len = strlen(event_name);
 733
 734         hash = jhash(event_name, name_len, 0);
 735         return &hash_table[hash & (hash_table_size - 1)];
 736 }
 737
 738 /*
 739  * Supports event creation while tracing session is active.
 740  */
 741 static
 742 int lttng_event_create(const struct lttng_event_desc *desc,
 743                 struct lttng_channel *chan)
 744 {
 745         struct lttng_event *event;
 746         struct lttng_ust_event_private *event_priv;
 747         struct lttng_session *session = chan->session;
 748         struct cds_hlist_head *head;
 749         int ret = 0;
 750         int notify_socket, loglevel;
 751         const char *uri;
 752
 753         head = borrow_hash_table_bucket(chan->session->events_ht.table,
 754                 LTTNG_UST_EVENT_HT_SIZE, desc);
 755
 756         notify_socket = lttng_get_notify_socket(session->owner);
 757         if (notify_socket < 0) {
 758                 ret = notify_socket;
 759                 goto socket_error;
 760         }
 761
 762         ret = lttng_create_all_event_enums(desc->nr_fields, desc->fields,
 763                         session);
 764         if (ret < 0) {
 765                 DBG("Error (%d) adding enum to session", ret);
 766                 goto create_enum_error;
 767         }
 768
 769         /*
 770          * Check if loglevel match. Refuse to connect event if not.
 771          */
 772         event = zmalloc(sizeof(struct lttng_event));
 773         if (!event) {
 774                 ret = -ENOMEM;
 775                 goto cache_error;
 776         }
 777         event_priv = zmalloc(sizeof(struct lttng_ust_event_private));
 778         if (!event_priv) {
 779                 ret = -ENOMEM;
 780                 goto priv_error;
 781         }
 782         event->priv = event_priv;
 783         event_priv->pub = event;
 784         event->chan = chan;
 785
 786         /* Event will be enabled by enabler sync. */
 787         event->enabled = 0;
 788         event->priv->registered = 0;
 789         CDS_INIT_LIST_HEAD(&event->filter_bytecode_runtime_head);
 790         CDS_INIT_LIST_HEAD(&event->priv->enablers_ref_head);
 791         event->priv->desc = desc;
 792
 793         if (desc->loglevel)
 794                 loglevel = *(*event->priv->desc->loglevel);
 795         else
 796                 loglevel = TRACE_DEFAULT;
 797         if (desc->u.ext.model_emf_uri)
 798                 uri = *(desc->u.ext.model_emf_uri);
 799         else
 800                 uri = NULL;
 801
 802         /* Fetch event ID from sessiond */
 803         ret = ustcomm_register_event(notify_socket,
 804                 session,
 805                 session->objd,
 806                 chan->objd,
 807                 desc->name,
 808                 loglevel,
 809                 desc->signature,
 810                 desc->nr_fields,
 811                 desc->fields,
 812                 uri,
 813                 &event->id);
 814         if (ret < 0) {
 815                 DBG("Error (%d) registering event to sessiond", ret);
 816                 goto sessiond_register_error;
 817         }
 818
 819         cds_list_add(&event->priv->node, &chan->session->events_head);
 820         cds_hlist_add_head(&event->priv->hlist, head);
 821         return 0;
 822
 823 sessiond_register_error:
 824         free(event_priv);
 825 priv_error:
 826         free(event);
 827 cache_error:
 828 create_enum_error:
 829 socket_error:
 830         return ret;
 831 }
 832
 833 static
 834 int lttng_event_notifier_create(const struct lttng_event_desc *desc,
 835                 uint64_t token, uint64_t error_counter_index,
 836                 struct lttng_event_notifier_group *event_notifier_group)
 837 {
 838         struct lttng_event_notifier *event_notifier;
 839         struct cds_hlist_head *head;
 840         int ret = 0;
 841
 842         /*
 843          * Get the hashtable bucket the created lttng_event_notifier object
 844          * should be inserted.
 845          */
 846         head = borrow_hash_table_bucket(
 847                 event_notifier_group->event_notifiers_ht.table,
 848                 LTTNG_UST_EVENT_NOTIFIER_HT_SIZE, desc);
 849
 850         event_notifier = zmalloc(sizeof(struct lttng_event_notifier));
 851         if (!event_notifier) {
 852                 ret = -ENOMEM;
 853                 goto error;
 854         }
 855
 856         event_notifier->group = event_notifier_group;
 857         event_notifier->user_token = token;
 858         event_notifier->error_counter_index = error_counter_index;
 859
 860         /* Event notifier will be enabled by enabler sync. */
 861         event_notifier->enabled = 0;
 862         event_notifier->registered = 0;
 863
 864         CDS_INIT_LIST_HEAD(&event_notifier->filter_bytecode_runtime_head);
 865         CDS_INIT_LIST_HEAD(&event_notifier->capture_bytecode_runtime_head);
 866         CDS_INIT_LIST_HEAD(&event_notifier->enablers_ref_head);
 867         event_notifier->desc = desc;
 868         event_notifier->notification_send = lttng_event_notifier_notification_send;
 869
 870         cds_list_add(&event_notifier->node,
 871                         &event_notifier_group->event_notifiers_head);
 872         cds_hlist_add_head(&event_notifier->hlist, head);
 873
 874         return 0;
 875
 876 error:
 877         return ret;
 878 }
 879
 880 static
 881 void _lttng_event_notifier_destroy(struct lttng_event_notifier *event_notifier)
 882 {
 883         struct lttng_enabler_ref *enabler_ref, *tmp_enabler_ref;
 884
 885         /* Remove from event_notifier list. */
 886         cds_list_del(&event_notifier->node);
 887         /* Remove from event_notifier hash table. */
 888         cds_hlist_del(&event_notifier->hlist);
 889
 890         lttng_free_event_notifier_filter_runtime(event_notifier);
 891
 892         /* Free event_notifier enabler refs */
 893         cds_list_for_each_entry_safe(enabler_ref, tmp_enabler_ref,
 894                         &event_notifier->enablers_ref_head, node)
 895                 free(enabler_ref);
 896         free(event_notifier);
 897 }
 898
 899 static
 900 int lttng_desc_match_star_glob_enabler(const struct lttng_event_desc *desc,
 901                 struct lttng_enabler *enabler)
 902 {
 903         int loglevel = 0;
 904         unsigned int has_loglevel = 0;
 905
 906         assert(enabler->format_type == LTTNG_ENABLER_FORMAT_STAR_GLOB);
 907         if (!strutils_star_glob_match(enabler->event_param.name, SIZE_MAX,
 908                         desc->name, SIZE_MAX))
 909                 return 0;
 910         if (desc->loglevel) {
 911                 loglevel = *(*desc->loglevel);
 912                 has_loglevel = 1;
 913         }
 914         if (!lttng_loglevel_match(loglevel,
 915                         has_loglevel,
 916                         enabler->event_param.loglevel_type,
 917                         enabler->event_param.loglevel))
 918                 return 0;
 919         return 1;
 920 }
 921
 922 static
 923 int lttng_desc_match_event_enabler(const struct lttng_event_desc *desc,
 924                 struct lttng_enabler *enabler)
 925 {
 926         int loglevel = 0;
 927         unsigned int has_loglevel = 0;
 928
 929         assert(enabler->format_type == LTTNG_ENABLER_FORMAT_EVENT);
 930         if (strcmp(desc->name, enabler->event_param.name))
 931                 return 0;
 932         if (desc->loglevel) {
 933                 loglevel = *(*desc->loglevel);
 934                 has_loglevel = 1;
 935         }
 936         if (!lttng_loglevel_match(loglevel,
 937                         has_loglevel,
 938                         enabler->event_param.loglevel_type,
 939                         enabler->event_param.loglevel))
 940                 return 0;
 941         return 1;
 942 }
 943
 944 static
 945 int lttng_desc_match_enabler(const struct lttng_event_desc *desc,
 946                 struct lttng_enabler *enabler)
 947 {
 948         switch (enabler->format_type) {
 949         case LTTNG_ENABLER_FORMAT_STAR_GLOB:
 950         {
 951                 struct lttng_ust_excluder_node *excluder;
 952
 953                 if (!lttng_desc_match_star_glob_enabler(desc, enabler)) {
 954                         return 0;
 955                 }
 956
 957                 /*
 958                  * If the matching event matches with an excluder,
 959                  * return 'does not match'
 960                  */
 961                 cds_list_for_each_entry(excluder, &enabler->excluder_head, node) {
 962                         int count;
 963
 964                         for (count = 0; count < excluder->excluder.count; count++) {
 965                                 int len;
 966                                 char *excluder_name;
 967
 968                                 excluder_name = (char *) (excluder->excluder.names)
 969                                                 + count * LTTNG_UST_SYM_NAME_LEN;
 970                                 len = strnlen(excluder_name, LTTNG_UST_SYM_NAME_LEN);
 971                                 if (len > 0 && strutils_star_glob_match(excluder_name, len, desc->name, SIZE_MAX))
 972                                         return 0;
 973                         }
 974                 }
 975                 return 1;
 976         }
 977         case LTTNG_ENABLER_FORMAT_EVENT:
 978                 return lttng_desc_match_event_enabler(desc, enabler);
 979         default:
 980                 return -EINVAL;
 981         }
 982 }
 983
 984 static
 985 int lttng_event_enabler_match_event(struct lttng_event_enabler *event_enabler,
 986                 struct lttng_event *event)
 987 {
 988         if (lttng_desc_match_enabler(event->priv->desc,
 989                         lttng_event_enabler_as_enabler(event_enabler))
 990                         && event->chan == event_enabler->chan)
 991                 return 1;
 992         else
 993                 return 0;
 994 }
 995
 996 static
 997 int lttng_event_notifier_enabler_match_event_notifier(
 998                 struct lttng_event_notifier_enabler *event_notifier_enabler,
 999                 struct lttng_event_notifier *event_notifier)
1000 {
1001         int desc_matches = lttng_desc_match_enabler(event_notifier->desc,
1002                 lttng_event_notifier_enabler_as_enabler(event_notifier_enabler));
1003
1004         if (desc_matches && event_notifier->group == event_notifier_enabler->group &&
1005                         event_notifier->user_token == event_notifier_enabler->user_token)
1006                 return 1;
1007         else
1008                 return 0;
1009 }
1010
1011 static
1012 struct lttng_enabler_ref *lttng_enabler_ref(
1013                 struct cds_list_head *enabler_ref_list,
1014                 struct lttng_enabler *enabler)
1015 {
1016         struct lttng_enabler_ref *enabler_ref;
1017
1018         cds_list_for_each_entry(enabler_ref, enabler_ref_list, node) {
1019                 if (enabler_ref->ref == enabler)
1020                         return enabler_ref;
1021         }
1022         return NULL;
1023 }
1024
1025 /*
1026  * Create struct lttng_event if it is missing and present in the list of
1027  * tracepoint probes.
1028  */
1029 static
1030 void lttng_create_event_if_missing(struct lttng_event_enabler *event_enabler)
1031 {
1032         struct lttng_session *session = event_enabler->chan->session;
1033         struct lttng_probe_desc *probe_desc;
1034         const struct lttng_event_desc *desc;
1035         struct lttng_ust_event_private *event_priv;
1036         int i;
1037         struct cds_list_head *probe_list;
1038
1039         probe_list = lttng_get_probe_list_head();
1040         /*
1041          * For each probe event, if we find that a probe event matches
1042          * our enabler, create an associated lttng_event if not
1043          * already present.
1044          */
1045         cds_list_for_each_entry(probe_desc, probe_list, head) {
1046                 for (i = 0; i < probe_desc->nr_events; i++) {
1047                         int ret;
1048                         bool found = false;
1049                         struct cds_hlist_head *head;
1050                         struct cds_hlist_node *node;
1051
1052                         desc = probe_desc->event_desc[i];
1053                         if (!lttng_desc_match_enabler(desc,
1054                                         lttng_event_enabler_as_enabler(event_enabler)))
1055                                 continue;
1056
1057                         head = borrow_hash_table_bucket(
1058                                 session->events_ht.table,
1059                                 LTTNG_UST_EVENT_HT_SIZE, desc);
1060
1061                         cds_hlist_for_each_entry(event_priv, node, head, hlist) {
1062                                 if (event_priv->desc == desc
1063                                                 && event_priv->pub->chan == event_enabler->chan) {
1064                                         found = true;
1065                                         break;
1066                                 }
1067                         }
1068                         if (found)
1069                                 continue;
1070
1071                         /*
1072                          * We need to create an event for this
1073                          * event probe.
1074                          */
1075                         ret = lttng_event_create(probe_desc->event_desc[i],
1076                                         event_enabler->chan);
1077                         if (ret) {
1078                                 DBG("Unable to create event %s, error %d\n",
1079                                         probe_desc->event_desc[i]->name, ret);
1080                         }
1081                 }
1082         }
1083 }
1084
1085 static
1086 void probe_provider_event_for_each(struct lttng_probe_desc *provider_desc,
1087                 void (*event_func)(struct lttng_session *session,
1088                         struct lttng_event *event),
1089                 void (*event_notifier_func)(struct lttng_event_notifier *event_notifier))
1090 {
1091         struct cds_hlist_node *node, *tmp_node;
1092         struct cds_list_head *sessionsp;
1093         unsigned int i;
1094
1095         /* Get handle on list of sessions. */
1096         sessionsp = lttng_get_sessions();
1097
1098         /*
1099          * Iterate over all events in the probe provider descriptions and
1100          * sessions to queue the unregistration of the events.
1101          */
1102         for (i = 0; i < provider_desc->nr_events; i++) {
1103                 const struct lttng_event_desc *event_desc;
1104                 struct lttng_event_notifier_group *event_notifier_group;
1105                 struct lttng_event_notifier *event_notifier;
1106                 struct lttng_session *session;
1107                 struct cds_hlist_head *head;
1108                 struct lttng_ust_event_private *event_priv;
1109
1110                 event_desc = provider_desc->event_desc[i];
1111
1112                 /*
1113                  * Iterate over all session to find the current event
1114                  * description.
1115                  */
1116                 cds_list_for_each_entry(session, sessionsp, node) {
1117                         /*
1118                          * Get the list of events in the hashtable bucket and
1119                          * iterate to find the event matching this descriptor.
1120                          */
1121                         head = borrow_hash_table_bucket(
1122                                 session->events_ht.table,
1123                                 LTTNG_UST_EVENT_HT_SIZE, event_desc);
1124
1125                         cds_hlist_for_each_entry_safe(event_priv, node, tmp_node, head, hlist) {
1126                                 if (event_desc == event_priv->desc) {
1127                                         event_func(session, event_priv->pub);
1128                                         break;
1129                                 }
1130                         }
1131                 }
1132
1133                 /*
1134                  * Iterate over all event_notifier groups to find the current event
1135                  * description.
1136                  */
1137                 cds_list_for_each_entry(event_notifier_group, &event_notifier_groups, node) {
1138                         /*
1139                          * Get the list of event_notifiers in the hashtable bucket and
1140                          * iterate to find the event_notifier matching this
1141                          * descriptor.
1142                          */
1143                         head = borrow_hash_table_bucket(
1144                                 event_notifier_group->event_notifiers_ht.table,
1145                                 LTTNG_UST_EVENT_NOTIFIER_HT_SIZE, event_desc);
1146
1147                         cds_hlist_for_each_entry_safe(event_notifier, node, tmp_node, head, hlist) {
1148                                 if (event_desc == event_notifier->desc) {
1149                                         event_notifier_func(event_notifier);
1150                                         break;
1151                                 }
1152                         }
1153                 }
1154         }
1155 }
1156
1157 static
1158 void _unregister_event(struct lttng_session *session,
1159                 struct lttng_event *event)
1160 {
1161         _lttng_event_unregister(event);
1162 }
1163
1164 static
1165 void _event_enum_destroy(struct lttng_session *session,
1166                 struct lttng_event *event)
1167 {
1168         unsigned int i;
1169
1170         /* Destroy enums of the current event. */
1171         for (i = 0; i < event->priv->desc->nr_fields; i++) {
1172                 const struct lttng_enum_desc *enum_desc;
1173                 const struct lttng_event_field *field;
1174                 struct lttng_enum *curr_enum;
1175
1176                 field = &(event->priv->desc->fields[i]);
1177                 switch (field->type.atype) {
1178                 case atype_enum:
1179                         enum_desc = field->type.u.legacy.basic.enumeration.desc;
1180                         break;
1181                 case atype_enum_nestable:
1182                         enum_desc = field->type.u.enum_nestable.desc;
1183                         break;
1184                 default:
1185                         continue;
1186                 }
1187
1188                 curr_enum = lttng_ust_enum_get_from_desc(session, enum_desc);
1189                 if (curr_enum) {
1190                         _lttng_enum_destroy(curr_enum);
1191                 }
1192         }
1193
1194         /* Destroy event. */
1195         _lttng_event_destroy(event);
1196 }
1197
1198 /*
1199  * Iterate over all the UST sessions to unregister and destroy all probes from
1200  * the probe provider descriptor received as argument. Must me called with the
1201  * ust_lock held.
1202  */
1203 void lttng_probe_provider_unregister_events(
1204                 struct lttng_probe_desc *provider_desc)
1205 {
1206         /*
1207          * Iterate over all events in the probe provider descriptions and sessions
1208          * to queue the unregistration of the events.
1209          */
1210         probe_provider_event_for_each(provider_desc, _unregister_event,
1211                 _lttng_event_notifier_unregister);
1212
1213         /* Wait for grace period. */
1214         lttng_ust_urcu_synchronize_rcu();
1215         /* Prune the unregistration queue. */
1216         __tracepoint_probe_prune_release_queue();
1217
1218         /*
1219          * It is now safe to destroy the events and remove them from the event list
1220          * and hashtables.
1221          */
1222         probe_provider_event_for_each(provider_desc, _event_enum_destroy,
1223                 _lttng_event_notifier_destroy);
1224 }
1225
1226 /*
1227  * Create events associated with an event enabler (if not already present),
1228  * and add backward reference from the event to the enabler.
1229  */
1230 static
1231 int lttng_event_enabler_ref_events(struct lttng_event_enabler *event_enabler)
1232 {
1233         struct lttng_session *session = event_enabler->chan->session;
1234         struct lttng_ust_event_private *event_priv;
1235
1236         if (!lttng_event_enabler_as_enabler(event_enabler)->enabled)
1237                 goto end;
1238
1239         /* First ensure that probe events are created for this enabler. */
1240         lttng_create_event_if_missing(event_enabler);
1241
1242         /* For each event matching enabler in session event list. */
1243         cds_list_for_each_entry(event_priv, &session->events_head, node) {
1244                 struct lttng_enabler_ref *enabler_ref;
1245
1246                 if (!lttng_event_enabler_match_event(event_enabler, event_priv->pub))
1247                         continue;
1248
1249                 enabler_ref = lttng_enabler_ref(&event_priv->enablers_ref_head,
1250                         lttng_event_enabler_as_enabler(event_enabler));
1251                 if (!enabler_ref) {
1252                         /*
1253                          * If no backward ref, create it.
1254                          * Add backward ref from event to enabler.
1255                          */
1256                         enabler_ref = zmalloc(sizeof(*enabler_ref));
1257                         if (!enabler_ref)
1258                                 return -ENOMEM;
1259                         enabler_ref->ref = lttng_event_enabler_as_enabler(
1260                                 event_enabler);
1261                         cds_list_add(&enabler_ref->node,
1262                                 &event_priv->enablers_ref_head);
1263                 }
1264
1265                 /*
1266                  * Link filter bytecodes if not linked yet.
1267                  */
1268                 lttng_enabler_link_bytecode(event_priv->desc,
1269                         &session->ctx,
1270                         &event_priv->pub->filter_bytecode_runtime_head,
1271                         &lttng_event_enabler_as_enabler(event_enabler)->filter_bytecode_head);
1272
1273                 /* TODO: merge event context. */
1274         }
1275 end:
1276         return 0;
1277 }
1278
1279 /*
1280  * Called at library load: connect the probe on all enablers matching
1281  * this event.
1282  * Called with session mutex held.
1283  */
1284 int lttng_fix_pending_events(void)
1285 {
1286         struct lttng_session *session;
1287
1288         cds_list_for_each_entry(session, &sessions, node) {
1289                 lttng_session_lazy_sync_event_enablers(session);
1290         }
1291         return 0;
1292 }
1293
1294 int lttng_fix_pending_event_notifiers(void)
1295 {
1296         struct lttng_event_notifier_group *event_notifier_group;
1297
1298         cds_list_for_each_entry(event_notifier_group, &event_notifier_groups, node) {
1299                 lttng_event_notifier_group_sync_enablers(event_notifier_group);
1300         }
1301         return 0;
1302 }
1303
1304 /*
1305  * For each session of the owner thread, execute pending statedump.
1306  * Only dump state for the sessions owned by the caller thread, because
1307  * we don't keep ust_lock across the entire iteration.
1308  */
1309 void lttng_handle_pending_statedump(void *owner)
1310 {
1311         struct lttng_session *session;
1312
1313         /* Execute state dump */
1314         do_lttng_ust_statedump(owner);
1315
1316         /* Clear pending state dump */
1317         if (ust_lock()) {
1318                 goto end;
1319         }
1320         cds_list_for_each_entry(session, &sessions, node) {
1321                 if (session->owner != owner)
1322                         continue;
1323                 if (!session->statedump_pending)
1324                         continue;
1325                 session->statedump_pending = 0;
1326         }
1327 end:
1328         ust_unlock();
1329         return;
1330 }
1331
1332 /*
1333  * Only used internally at session destruction.
1334  */
1335 static
1336 void _lttng_event_destroy(struct lttng_event *event)
1337 {
1338         struct lttng_enabler_ref *enabler_ref, *tmp_enabler_ref;
1339
1340         /* Remove from event list. */
1341         cds_list_del(&event->priv->node);
1342         /* Remove from event hash table. */
1343         cds_hlist_del(&event->priv->hlist);
1344
1345         lttng_destroy_context(event->ctx);
1346         lttng_free_event_filter_runtime(event);
1347         /* Free event enabler refs */
1348         cds_list_for_each_entry_safe(enabler_ref, tmp_enabler_ref,
1349                         &event->priv->enablers_ref_head, node)
1350                 free(enabler_ref);
1351         free(event->priv);
1352         free(event);
1353 }
1354
1355 static
1356 void _lttng_enum_destroy(struct lttng_enum *_enum)
1357 {
1358         cds_list_del(&_enum->node);
1359         cds_hlist_del(&_enum->hlist);
1360         free(_enum);
1361 }
1362
1363 void lttng_ust_events_exit(void)
1364 {
1365         struct lttng_session *session, *tmpsession;
1366
1367         cds_list_for_each_entry_safe(session, tmpsession, &sessions, node)
1368                 lttng_session_destroy(session);
1369 }
1370
1371 /*
1372  * Enabler management.
1373  */
1374 struct lttng_event_enabler *lttng_event_enabler_create(
1375                 enum lttng_enabler_format_type format_type,
1376                 struct lttng_ust_event *event_param,
1377                 struct lttng_channel *chan)
1378 {
1379         struct lttng_event_enabler *event_enabler;
1380
1381         event_enabler = zmalloc(sizeof(*event_enabler));
1382         if (!event_enabler)
1383                 return NULL;
1384         event_enabler->base.format_type = format_type;
1385         CDS_INIT_LIST_HEAD(&event_enabler->base.filter_bytecode_head);
1386         CDS_INIT_LIST_HEAD(&event_enabler->base.excluder_head);
1387         memcpy(&event_enabler->base.event_param, event_param,
1388                 sizeof(event_enabler->base.event_param));
1389         event_enabler->chan = chan;
1390         /* ctx left NULL */
1391         event_enabler->base.enabled = 0;
1392         cds_list_add(&event_enabler->node, &event_enabler->chan->session->enablers_head);
1393         lttng_session_lazy_sync_event_enablers(event_enabler->chan->session);
1394
1395         return event_enabler;
1396 }
1397
1398 struct lttng_event_notifier_enabler *lttng_event_notifier_enabler_create(
1399                 struct lttng_event_notifier_group *event_notifier_group,
1400                 enum lttng_enabler_format_type format_type,
1401                 struct lttng_ust_event_notifier *event_notifier_param)
1402 {
1403         struct lttng_event_notifier_enabler *event_notifier_enabler;
1404
1405         event_notifier_enabler = zmalloc(sizeof(*event_notifier_enabler));
1406         if (!event_notifier_enabler)
1407                 return NULL;
1408         event_notifier_enabler->base.format_type = format_type;
1409         CDS_INIT_LIST_HEAD(&event_notifier_enabler->base.filter_bytecode_head);
1410         CDS_INIT_LIST_HEAD(&event_notifier_enabler->capture_bytecode_head);
1411         CDS_INIT_LIST_HEAD(&event_notifier_enabler->base.excluder_head);
1412
1413         event_notifier_enabler->user_token = event_notifier_param->event.token;
1414         event_notifier_enabler->error_counter_index = event_notifier_param->error_counter_index;
1415         event_notifier_enabler->num_captures = 0;
1416
1417         memcpy(&event_notifier_enabler->base.event_param.name,
1418                 event_notifier_param->event.name,
1419                 sizeof(event_notifier_enabler->base.event_param.name));
1420         event_notifier_enabler->base.event_param.instrumentation =
1421                 event_notifier_param->event.instrumentation;
1422         event_notifier_enabler->base.event_param.loglevel =
1423                 event_notifier_param->event.loglevel;
1424         event_notifier_enabler->base.event_param.loglevel_type =
1425                 event_notifier_param->event.loglevel_type;
1426
1427         event_notifier_enabler->base.enabled = 0;
1428         event_notifier_enabler->group = event_notifier_group;
1429
1430         cds_list_add(&event_notifier_enabler->node,
1431                         &event_notifier_group->enablers_head);
1432
1433         lttng_event_notifier_group_sync_enablers(event_notifier_group);
1434
1435         return event_notifier_enabler;
1436 }
1437
1438 int lttng_event_enabler_enable(struct lttng_event_enabler *event_enabler)
1439 {
1440         lttng_event_enabler_as_enabler(event_enabler)->enabled = 1;
1441         lttng_session_lazy_sync_event_enablers(event_enabler->chan->session);
1442
1443         return 0;
1444 }
1445
1446 int lttng_event_enabler_disable(struct lttng_event_enabler *event_enabler)
1447 {
1448         lttng_event_enabler_as_enabler(event_enabler)->enabled = 0;
1449         lttng_session_lazy_sync_event_enablers(event_enabler->chan->session);
1450
1451         return 0;
1452 }
1453
1454 static
1455 void _lttng_enabler_attach_filter_bytecode(struct lttng_enabler *enabler,
1456                 struct lttng_ust_bytecode_node **bytecode)
1457 {
1458         (*bytecode)->enabler = enabler;
1459         cds_list_add_tail(&(*bytecode)->node, &enabler->filter_bytecode_head);
1460         /* Take ownership of bytecode */
1461         *bytecode = NULL;
1462 }
1463
1464 int lttng_event_enabler_attach_filter_bytecode(struct lttng_event_enabler *event_enabler,
1465                 struct lttng_ust_bytecode_node **bytecode)
1466 {
1467         _lttng_enabler_attach_filter_bytecode(
1468                 lttng_event_enabler_as_enabler(event_enabler), bytecode);
1469
1470         lttng_session_lazy_sync_event_enablers(event_enabler->chan->session);
1471         return 0;
1472 }
1473
1474 static
1475 void _lttng_enabler_attach_exclusion(struct lttng_enabler *enabler,
1476                 struct lttng_ust_excluder_node **excluder)
1477 {
1478         (*excluder)->enabler = enabler;
1479         cds_list_add_tail(&(*excluder)->node, &enabler->excluder_head);
1480         /* Take ownership of excluder */
1481         *excluder = NULL;
1482 }
1483
1484 int lttng_event_enabler_attach_exclusion(struct lttng_event_enabler *event_enabler,
1485                 struct lttng_ust_excluder_node **excluder)
1486 {
1487         _lttng_enabler_attach_exclusion(
1488                 lttng_event_enabler_as_enabler(event_enabler), excluder);
1489
1490         lttng_session_lazy_sync_event_enablers(event_enabler->chan->session);
1491         return 0;
1492 }
1493
1494 int lttng_event_notifier_enabler_enable(
1495                 struct lttng_event_notifier_enabler *event_notifier_enabler)
1496 {
1497         lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->enabled = 1;
1498         lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
1499
1500         return 0;
1501 }
1502
1503 int lttng_event_notifier_enabler_disable(
1504                 struct lttng_event_notifier_enabler *event_notifier_enabler)
1505 {
1506         lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->enabled = 0;
1507         lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
1508
1509         return 0;
1510 }
1511
1512 int lttng_event_notifier_enabler_attach_filter_bytecode(
1513                 struct lttng_event_notifier_enabler *event_notifier_enabler,
1514                 struct lttng_ust_bytecode_node **bytecode)
1515 {
1516         _lttng_enabler_attach_filter_bytecode(
1517                 lttng_event_notifier_enabler_as_enabler(event_notifier_enabler),
1518                 bytecode);
1519
1520         lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
1521         return 0;
1522 }
1523
1524 int lttng_event_notifier_enabler_attach_capture_bytecode(
1525                 struct lttng_event_notifier_enabler *event_notifier_enabler,
1526                 struct lttng_ust_bytecode_node **bytecode)
1527 {
1528         (*bytecode)->enabler = lttng_event_notifier_enabler_as_enabler(
1529                         event_notifier_enabler);
1530         cds_list_add_tail(&(*bytecode)->node,
1531                         &event_notifier_enabler->capture_bytecode_head);
1532         /* Take ownership of bytecode */
1533         *bytecode = NULL;
1534         event_notifier_enabler->num_captures++;
1535
1536         lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
1537         return 0;
1538 }
1539
1540 int lttng_event_notifier_enabler_attach_exclusion(
1541                 struct lttng_event_notifier_enabler *event_notifier_enabler,
1542                 struct lttng_ust_excluder_node **excluder)
1543 {
1544         _lttng_enabler_attach_exclusion(
1545                 lttng_event_notifier_enabler_as_enabler(event_notifier_enabler),
1546                 excluder);
1547
1548         lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
1549         return 0;
1550 }
1551
1552 int lttng_attach_context(struct lttng_ust_context *context_param,
1553                 union ust_args *uargs,
1554                 struct lttng_ctx **ctx, struct lttng_session *session)
1555 {
1556         /*
1557          * We cannot attach a context after trace has been started for a
1558          * session because the metadata does not allow expressing this
1559          * information outside of the original channel scope.
1560          */
1561         if (session->been_active)
1562                 return -EPERM;
1563
1564         switch (context_param->ctx) {
1565         case LTTNG_UST_CONTEXT_PTHREAD_ID:
1566                 return lttng_add_pthread_id_to_ctx(ctx);
1567         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
1568         {
1569                 struct lttng_ust_perf_counter_ctx *perf_ctx_param;
1570
1571                 perf_ctx_param = &context_param->u.perf_counter;
1572                 return lttng_add_perf_counter_to_ctx(
1573                         perf_ctx_param->type,
1574                         perf_ctx_param->config,
1575                         perf_ctx_param->name,
1576                         ctx);
1577         }
1578         case LTTNG_UST_CONTEXT_VTID:
1579                 return lttng_add_vtid_to_ctx(ctx);
1580         case LTTNG_UST_CONTEXT_VPID:
1581                 return lttng_add_vpid_to_ctx(ctx);
1582         case LTTNG_UST_CONTEXT_PROCNAME:
1583                 return lttng_add_procname_to_ctx(ctx);
1584         case LTTNG_UST_CONTEXT_IP:
1585                 return lttng_add_ip_to_ctx(ctx);
1586         case LTTNG_UST_CONTEXT_CPU_ID:
1587                 return lttng_add_cpu_id_to_ctx(ctx);
1588         case LTTNG_UST_CONTEXT_APP_CONTEXT:
1589                 return lttng_ust_add_app_context_to_ctx_rcu(uargs->app_context.ctxname,
1590                         ctx);
1591         case LTTNG_UST_CONTEXT_CGROUP_NS:
1592                 return lttng_add_cgroup_ns_to_ctx(ctx);
1593         case LTTNG_UST_CONTEXT_IPC_NS:
1594                 return lttng_add_ipc_ns_to_ctx(ctx);
1595         case LTTNG_UST_CONTEXT_MNT_NS:
1596                 return lttng_add_mnt_ns_to_ctx(ctx);
1597         case LTTNG_UST_CONTEXT_NET_NS:
1598                 return lttng_add_net_ns_to_ctx(ctx);
1599         case LTTNG_UST_CONTEXT_PID_NS:
1600                 return lttng_add_pid_ns_to_ctx(ctx);
1601         case LTTNG_UST_CONTEXT_TIME_NS:
1602                 return lttng_add_time_ns_to_ctx(ctx);
1603         case LTTNG_UST_CONTEXT_USER_NS:
1604                 return lttng_add_user_ns_to_ctx(ctx);
1605         case LTTNG_UST_CONTEXT_UTS_NS:
1606                 return lttng_add_uts_ns_to_ctx(ctx);
1607         case LTTNG_UST_CONTEXT_VUID:
1608                 return lttng_add_vuid_to_ctx(ctx);
1609         case LTTNG_UST_CONTEXT_VEUID:
1610                 return lttng_add_veuid_to_ctx(ctx);
1611         case LTTNG_UST_CONTEXT_VSUID:
1612                 return lttng_add_vsuid_to_ctx(ctx);
1613         case LTTNG_UST_CONTEXT_VGID:
1614                 return lttng_add_vgid_to_ctx(ctx);
1615         case LTTNG_UST_CONTEXT_VEGID:
1616                 return lttng_add_vegid_to_ctx(ctx);
1617         case LTTNG_UST_CONTEXT_VSGID:
1618                 return lttng_add_vsgid_to_ctx(ctx);
1619         default:
1620                 return -EINVAL;
1621         }
1622 }
1623
1624 int lttng_event_enabler_attach_context(struct lttng_event_enabler *enabler,
1625                 struct lttng_ust_context *context_param)
1626 {
1627         return -ENOSYS;
1628 }
1629
1630 void lttng_event_enabler_destroy(struct lttng_event_enabler *event_enabler)
1631 {
1632         if (!event_enabler) {
1633                 return;
1634         }
1635         cds_list_del(&event_enabler->node);
1636
1637         lttng_enabler_destroy(lttng_event_enabler_as_enabler(event_enabler));
1638
1639         lttng_destroy_context(event_enabler->ctx);
1640         free(event_enabler);
1641 }
1642
1643 /*
1644  * lttng_session_sync_event_enablers should be called just before starting a
1645  * session.
1646  */
1647 static
1648 void lttng_session_sync_event_enablers(struct lttng_session *session)
1649 {
1650         struct lttng_event_enabler *event_enabler;
1651         struct lttng_ust_event_private *event_priv;
1652
1653         cds_list_for_each_entry(event_enabler, &session->enablers_head, node)
1654                 lttng_event_enabler_ref_events(event_enabler);
1655         /*
1656          * For each event, if at least one of its enablers is enabled,
1657          * and its channel and session transient states are enabled, we
1658          * enable the event, else we disable it.
1659          */
1660         cds_list_for_each_entry(event_priv, &session->events_head, node) {
1661                 struct lttng_enabler_ref *enabler_ref;
1662                 struct lttng_bytecode_runtime *runtime;
1663                 int enabled = 0, has_enablers_without_bytecode = 0;
1664
1665                 /* Enable events */
1666                 cds_list_for_each_entry(enabler_ref,
1667                                 &event_priv->enablers_ref_head, node) {
1668                         if (enabler_ref->ref->enabled) {
1669                                 enabled = 1;
1670                                 break;
1671                         }
1672                 }
1673                 /*
1674                  * Enabled state is based on union of enablers, with
1675                  * intesection of session and channel transient enable
1676                  * states.
1677                  */
1678                 enabled = enabled && session->tstate && event_priv->pub->chan->tstate;
1679
1680                 CMM_STORE_SHARED(event_priv->pub->enabled, enabled);
1681                 /*
1682                  * Sync tracepoint registration with event enabled
1683                  * state.
1684                  */
1685                 if (enabled) {
1686                         if (!event_priv->registered)
1687                                 register_event(event_priv->pub);
1688                 } else {
1689                         if (event_priv->registered)
1690                                 unregister_event(event_priv->pub);
1691                 }
1692
1693                 /* Check if has enablers without bytecode enabled */
1694                 cds_list_for_each_entry(enabler_ref,
1695                                 &event_priv->enablers_ref_head, node) {
1696                         if (enabler_ref->ref->enabled
1697                                         && cds_list_empty(&enabler_ref->ref->filter_bytecode_head)) {
1698                                 has_enablers_without_bytecode = 1;
1699                                 break;
1700                         }
1701                 }
1702                 event_priv->pub->has_enablers_without_bytecode =
1703                         has_enablers_without_bytecode;
1704
1705                 /* Enable filters */
1706                 cds_list_for_each_entry(runtime,
1707                                 &event_priv->pub->filter_bytecode_runtime_head, node) {
1708                         lttng_bytecode_filter_sync_state(runtime);
1709                 }
1710         }
1711         __tracepoint_probe_prune_release_queue();
1712 }
1713
1714 /* Support for event notifier is introduced by probe provider major version 2. */
1715 static
1716 bool lttng_ust_probe_supports_event_notifier(struct lttng_probe_desc *probe_desc)
1717 {
1718         return probe_desc->major >= 2;
1719 }
1720
1721 static
1722 void lttng_create_event_notifier_if_missing(
1723                 struct lttng_event_notifier_enabler *event_notifier_enabler)
1724 {
1725         struct lttng_event_notifier_group *event_notifier_group = event_notifier_enabler->group;
1726         struct lttng_probe_desc *probe_desc;
1727         struct cds_list_head *probe_list;
1728         int i;
1729
1730         probe_list = lttng_get_probe_list_head();
1731
1732         cds_list_for_each_entry(probe_desc, probe_list, head) {
1733                 for (i = 0; i < probe_desc->nr_events; i++) {
1734                         int ret;
1735                         bool found = false;
1736                         const struct lttng_event_desc *desc;
1737                         struct lttng_event_notifier *event_notifier;
1738                         struct cds_hlist_head *head;
1739                         struct cds_hlist_node *node;
1740
1741                         desc = probe_desc->event_desc[i];
1742
1743                         if (!lttng_desc_match_enabler(desc,
1744                                         lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)))
1745                                 continue;
1746
1747                         /*
1748                          * Given the current event_notifier group, get the bucket that
1749                          * the target event_notifier would be if it was already
1750                          * created.
1751                          */
1752                         head = borrow_hash_table_bucket(
1753                                 event_notifier_group->event_notifiers_ht.table,
1754                                 LTTNG_UST_EVENT_NOTIFIER_HT_SIZE, desc);
1755
1756                         cds_hlist_for_each_entry(event_notifier, node, head, hlist) {
1757                                 /*
1758                                  * Check if event_notifier already exists by checking
1759                                  * if the event_notifier and enabler share the same
1760                                  * description and id.
1761                                  */
1762                                 if (event_notifier->desc == desc &&
1763                                                 event_notifier->user_token == event_notifier_enabler->user_token) {
1764                                         found = true;
1765                                         break;
1766                                 }
1767                         }
1768
1769                         if (found)
1770                                 continue;
1771
1772                         /* Check that the probe supports event notifiers, else report the error. */
1773                         if (!lttng_ust_probe_supports_event_notifier(probe_desc)) {
1774                                 ERR("Probe \"%s\" contains event \"%s\" which matches an enabled event notifier, "
1775                                         "but its version (%u.%u) is too old and does not implement event notifiers. "
1776                                         "It needs to be recompiled against a newer version of LTTng-UST, otherwise "
1777                                         "this event will not generate any notification.",
1778                                         probe_desc->provider,
1779                                         desc->name,
1780                                         probe_desc->major,
1781                                         probe_desc->minor);
1782                                 continue;
1783                         }
1784                         /*
1785                          * We need to create a event_notifier for this event probe.
1786                          */
1787                         ret = lttng_event_notifier_create(desc,
1788                                 event_notifier_enabler->user_token,
1789                                 event_notifier_enabler->error_counter_index,
1790                                 event_notifier_group);
1791                         if (ret) {
1792                                 DBG("Unable to create event_notifier %s, error %d\n",
1793                                         probe_desc->event_desc[i]->name, ret);
1794                         }
1795                 }
1796         }
1797 }
1798
1799 /*
1800  * Create event_notifiers associated with a event_notifier enabler (if not already present).
1801  */
1802 static
1803 int lttng_event_notifier_enabler_ref_event_notifiers(
1804                 struct lttng_event_notifier_enabler *event_notifier_enabler)
1805 {
1806         struct lttng_event_notifier_group *event_notifier_group = event_notifier_enabler->group;
1807         struct lttng_event_notifier *event_notifier;
1808
1809          /*
1810           * Only try to create event_notifiers for enablers that are enabled, the user
1811           * might still be attaching filter or exclusion to the
1812           * event_notifier_enabler.
1813           */
1814         if (!lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->enabled)
1815                 goto end;
1816
1817         /* First, ensure that probe event_notifiers are created for this enabler. */
1818         lttng_create_event_notifier_if_missing(event_notifier_enabler);
1819
1820         /* Link the created event_notifier with its associated enabler. */
1821         cds_list_for_each_entry(event_notifier, &event_notifier_group->event_notifiers_head, node) {
1822                 struct lttng_enabler_ref *enabler_ref;
1823
1824                 if (!lttng_event_notifier_enabler_match_event_notifier(event_notifier_enabler, event_notifier))
1825                         continue;
1826
1827                 enabler_ref = lttng_enabler_ref(&event_notifier->enablers_ref_head,
1828                         lttng_event_notifier_enabler_as_enabler(event_notifier_enabler));
1829                 if (!enabler_ref) {
1830                         /*
1831                          * If no backward ref, create it.
1832                          * Add backward ref from event_notifier to enabler.
1833                          */
1834                         enabler_ref = zmalloc(sizeof(*enabler_ref));
1835                         if (!enabler_ref)
1836                                 return -ENOMEM;
1837
1838                         enabler_ref->ref = lttng_event_notifier_enabler_as_enabler(
1839                                 event_notifier_enabler);
1840                         cds_list_add(&enabler_ref->node,
1841                                 &event_notifier->enablers_ref_head);
1842                 }
1843
1844                 /*
1845                  * Link filter bytecodes if not linked yet.
1846                  */
1847                 lttng_enabler_link_bytecode(event_notifier->desc,
1848                         &event_notifier_group->ctx,
1849                         &event_notifier->filter_bytecode_runtime_head,
1850                         &lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->filter_bytecode_head);
1851
1852                 /*
1853                  * Link capture bytecodes if not linked yet.
1854                  */
1855                 lttng_enabler_link_bytecode(event_notifier->desc,
1856                         &event_notifier_group->ctx, &event_notifier->capture_bytecode_runtime_head,
1857                         &event_notifier_enabler->capture_bytecode_head);
1858
1859                 event_notifier->num_captures = event_notifier_enabler->num_captures;
1860         }
1861 end:
1862         return 0;
1863 }
1864
1865 static
1866 void lttng_event_notifier_group_sync_enablers(struct lttng_event_notifier_group *event_notifier_group)
1867 {
1868         struct lttng_event_notifier_enabler *event_notifier_enabler;
1869         struct lttng_event_notifier *event_notifier;
1870
1871         cds_list_for_each_entry(event_notifier_enabler, &event_notifier_group->enablers_head, node)
1872                 lttng_event_notifier_enabler_ref_event_notifiers(event_notifier_enabler);
1873
1874         /*
1875          * For each event_notifier, if at least one of its enablers is enabled,
1876          * we enable the event_notifier, else we disable it.
1877          */
1878         cds_list_for_each_entry(event_notifier, &event_notifier_group->event_notifiers_head, node) {
1879                 struct lttng_enabler_ref *enabler_ref;
1880                 struct lttng_bytecode_runtime *runtime;
1881                 int enabled = 0, has_enablers_without_bytecode = 0;
1882
1883                 /* Enable event_notifiers */
1884                 cds_list_for_each_entry(enabler_ref,
1885                                 &event_notifier->enablers_ref_head, node) {
1886                         if (enabler_ref->ref->enabled) {
1887                                 enabled = 1;
1888                                 break;
1889                         }
1890                 }
1891
1892                 CMM_STORE_SHARED(event_notifier->enabled, enabled);
1893                 /*
1894                  * Sync tracepoint registration with event_notifier enabled
1895                  * state.
1896                  */
1897                 if (enabled) {
1898                         if (!event_notifier->registered)
1899                                 register_event_notifier(event_notifier);
1900                 } else {
1901                         if (event_notifier->registered)
1902                                 unregister_event_notifier(event_notifier);
1903                 }
1904
1905                 /* Check if has enablers without bytecode enabled */
1906                 cds_list_for_each_entry(enabler_ref,
1907                                 &event_notifier->enablers_ref_head, node) {
1908                         if (enabler_ref->ref->enabled
1909                                         && cds_list_empty(&enabler_ref->ref->filter_bytecode_head)) {
1910                                 has_enablers_without_bytecode = 1;
1911                                 break;
1912                         }
1913                 }
1914                 event_notifier->has_enablers_without_bytecode =
1915                         has_enablers_without_bytecode;
1916
1917                 /* Enable filters */
1918                 cds_list_for_each_entry(runtime,
1919                                 &event_notifier->filter_bytecode_runtime_head, node) {
1920                         lttng_bytecode_filter_sync_state(runtime);
1921                 }
1922
1923                 /* Enable captures. */
1924                 cds_list_for_each_entry(runtime,
1925                                 &event_notifier->capture_bytecode_runtime_head, node) {
1926                         lttng_bytecode_capture_sync_state(runtime);
1927                 }
1928         }
1929         __tracepoint_probe_prune_release_queue();
1930 }
1931
1932 /*
1933  * Apply enablers to session events, adding events to session if need
1934  * be. It is required after each modification applied to an active
1935  * session, and right before session "start".
1936  * "lazy" sync means we only sync if required.
1937  */
1938 static
1939 void lttng_session_lazy_sync_event_enablers(struct lttng_session *session)
1940 {
1941         /* We can skip if session is not active */
1942         if (!session->active)
1943                 return;
1944         lttng_session_sync_event_enablers(session);
1945 }
1946
1947 /*
1948  * Update all sessions with the given app context.
1949  * Called with ust lock held.
1950  * This is invoked when an application context gets loaded/unloaded. It
1951  * ensures the context callbacks are in sync with the application
1952  * context (either app context callbacks, or dummy callbacks).
1953  */
1954 void lttng_ust_context_set_session_provider(const char *name,
1955                 size_t (*get_size)(struct lttng_ctx_field *field, size_t offset),
1956                 void (*record)(struct lttng_ctx_field *field,
1957                         struct lttng_ust_lib_ring_buffer_ctx *ctx,
1958                         struct lttng_channel *chan),
1959                 void (*get_value)(struct lttng_ctx_field *field,
1960                         struct lttng_ctx_value *value))
1961 {
1962         struct lttng_session *session;
1963
1964         cds_list_for_each_entry(session, &sessions, node) {
1965                 struct lttng_channel *chan;
1966                 struct lttng_ust_event_private *event_priv;
1967                 int ret;
1968
1969                 ret = lttng_ust_context_set_provider_rcu(&session->ctx,
1970                                 name, get_size, record, get_value);
1971                 if (ret)
1972                         abort();
1973                 cds_list_for_each_entry(chan, &session->chan_head, node) {
1974                         ret = lttng_ust_context_set_provider_rcu(&chan->ctx,
1975                                         name, get_size, record, get_value);
1976                         if (ret)
1977                                 abort();
1978                 }
1979                 cds_list_for_each_entry(event_priv, &session->events_head, node) {
1980                         ret = lttng_ust_context_set_provider_rcu(&event_priv->pub->ctx,
1981                                         name, get_size, record, get_value);
1982                         if (ret)
1983                                 abort();
1984                 }
1985         }
1986 }
1987
1988 /*
1989  * Update all event_notifier groups with the given app context.
1990  * Called with ust lock held.
1991  * This is invoked when an application context gets loaded/unloaded. It
1992  * ensures the context callbacks are in sync with the application
1993  * context (either app context callbacks, or dummy callbacks).
1994  */
1995 void lttng_ust_context_set_event_notifier_group_provider(const char *name,
1996                 size_t (*get_size)(struct lttng_ctx_field *field, size_t offset),
1997                 void (*record)(struct lttng_ctx_field *field,
1998                         struct lttng_ust_lib_ring_buffer_ctx *ctx,
1999                         struct lttng_channel *chan),
2000                 void (*get_value)(struct lttng_ctx_field *field,
2001                         struct lttng_ctx_value *value))
2002 {
2003         struct lttng_event_notifier_group *event_notifier_group;
2004
2005         cds_list_for_each_entry(event_notifier_group, &event_notifier_groups, node) {
2006                 int ret;
2007
2008                 ret = lttng_ust_context_set_provider_rcu(
2009                                 &event_notifier_group->ctx,
2010                                 name, get_size, record, get_value);
2011                 if (ret)
2012                         abort();
2013         }
2014 }