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_ust_session_private *iter;
  94
  95         cds_list_for_each_entry(iter, &sessions, node) {
  96                 if (iter->pub->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         struct lttng_ust_session_private *session_priv;
 136         int i;
 137
 138         session = zmalloc(sizeof(struct lttng_session));
 139         if (!session)
 140                 return NULL;
 141         session->struct_size = sizeof(struct lttng_session);
 142         session_priv = zmalloc(sizeof(struct lttng_ust_session_private));
 143         if (!session_priv) {
 144                 free(session);
 145                 return NULL;
 146         }
 147         session->priv = session_priv;
 148         session_priv->pub = session;
 149         if (lttng_context_init_all(&session->priv->ctx)) {
 150                 free(session_priv);
 151                 free(session);
 152                 return NULL;
 153         }
 154         CDS_INIT_LIST_HEAD(&session->priv->chan_head);
 155         CDS_INIT_LIST_HEAD(&session->priv->events_head);
 156         CDS_INIT_LIST_HEAD(&session->priv->enums_head);
 157         CDS_INIT_LIST_HEAD(&session->priv->enablers_head);
 158         for (i = 0; i < LTTNG_UST_EVENT_HT_SIZE; i++)
 159                 CDS_INIT_HLIST_HEAD(&session->priv->events_ht.table[i]);
 160         for (i = 0; i < LTTNG_UST_ENUM_HT_SIZE; i++)
 161                 CDS_INIT_HLIST_HEAD(&session->priv->enums_ht.table[i]);
 162         cds_list_add(&session->priv->node, &sessions);
 163         return session;
 164 }
 165
 166 struct lttng_counter *lttng_ust_counter_create(
 167                 const char *counter_transport_name,
 168                 size_t number_dimensions, const struct lttng_counter_dimension *dimensions)
 169 {
 170         struct lttng_counter_transport *counter_transport = NULL;
 171         struct lttng_counter *counter = NULL;
 172
 173         counter_transport = lttng_counter_transport_find(counter_transport_name);
 174         if (!counter_transport)
 175                 goto notransport;
 176         counter = zmalloc(sizeof(struct lttng_counter));
 177         if (!counter)
 178                 goto nomem;
 179
 180         counter->ops = &counter_transport->ops;
 181         counter->transport = counter_transport;
 182
 183         counter->counter = counter->ops->counter_create(
 184                         number_dimensions, dimensions, 0,
 185                         -1, 0, NULL, false);
 186         if (!counter->counter) {
 187                 goto create_error;
 188         }
 189
 190         return counter;
 191
 192 create_error:
 193         free(counter);
 194 nomem:
 195 notransport:
 196         return NULL;
 197 }
 198
 199 static
 200 void lttng_ust_counter_destroy(struct lttng_counter *counter)
 201 {
 202         counter->ops->counter_destroy(counter->counter);
 203         free(counter);
 204 }
 205
 206 struct lttng_event_notifier_group *lttng_event_notifier_group_create(void)
 207 {
 208         struct lttng_event_notifier_group *event_notifier_group;
 209         int i;
 210
 211         event_notifier_group = zmalloc(sizeof(struct lttng_event_notifier_group));
 212         if (!event_notifier_group)
 213                 return NULL;
 214
 215         /* Add all contexts. */
 216         if (lttng_context_init_all(&event_notifier_group->ctx)) {
 217                 free(event_notifier_group);
 218                 return NULL;
 219         }
 220
 221         CDS_INIT_LIST_HEAD(&event_notifier_group->enablers_head);
 222         CDS_INIT_LIST_HEAD(&event_notifier_group->event_notifiers_head);
 223         for (i = 0; i < LTTNG_UST_EVENT_NOTIFIER_HT_SIZE; i++)
 224                 CDS_INIT_HLIST_HEAD(&event_notifier_group->event_notifiers_ht.table[i]);
 225
 226         cds_list_add(&event_notifier_group->node, &event_notifier_groups);
 227
 228         return event_notifier_group;
 229 }
 230
 231 /*
 232  * Only used internally at session destruction.
 233  */
 234 static
 235 void _lttng_channel_unmap(struct lttng_channel *lttng_chan)
 236 {
 237         struct channel *chan;
 238         struct lttng_ust_shm_handle *handle;
 239
 240         cds_list_del(&lttng_chan->node);
 241         lttng_destroy_context(lttng_chan->ctx);
 242         chan = lttng_chan->chan;
 243         handle = lttng_chan->handle;
 244         /*
 245          * note: lttng_chan is private data contained within handle. It
 246          * will be freed along with the handle.
 247          */
 248         channel_destroy(chan, handle, 0);
 249 }
 250
 251 static
 252 void register_event(struct lttng_event *event)
 253 {
 254         int ret;
 255         const struct lttng_event_desc *desc;
 256
 257         assert(event->priv->registered == 0);
 258         desc = event->priv->desc;
 259         ret = __tracepoint_probe_register_queue_release(desc->name,
 260                         desc->probe_callback,
 261                         event, desc->signature);
 262         WARN_ON_ONCE(ret);
 263         if (!ret)
 264                 event->priv->registered = 1;
 265 }
 266
 267 static
 268 void register_event_notifier(struct lttng_event_notifier *event_notifier)
 269 {
 270         int ret;
 271         const struct lttng_event_desc *desc;
 272
 273         assert(event_notifier->registered == 0);
 274         desc = event_notifier->desc;
 275         ret = __tracepoint_probe_register_queue_release(desc->name,
 276                 desc->u.ext.event_notifier_callback, event_notifier, desc->signature);
 277         WARN_ON_ONCE(ret);
 278         if (!ret)
 279                 event_notifier->registered = 1;
 280 }
 281
 282 static
 283 void unregister_event(struct lttng_event *event)
 284 {
 285         int ret;
 286         const struct lttng_event_desc *desc;
 287
 288         assert(event->priv->registered == 1);
 289         desc = event->priv->desc;
 290         ret = __tracepoint_probe_unregister_queue_release(desc->name,
 291                         desc->probe_callback,
 292                         event);
 293         WARN_ON_ONCE(ret);
 294         if (!ret)
 295                 event->priv->registered = 0;
 296 }
 297
 298 static
 299 void unregister_event_notifier(struct lttng_event_notifier *event_notifier)
 300 {
 301         int ret;
 302         const struct lttng_event_desc *desc;
 303
 304         assert(event_notifier->registered == 1);
 305         desc = event_notifier->desc;
 306         ret = __tracepoint_probe_unregister_queue_release(desc->name,
 307                 desc->u.ext.event_notifier_callback, event_notifier);
 308         WARN_ON_ONCE(ret);
 309         if (!ret)
 310                 event_notifier->registered = 0;
 311 }
 312
 313 /*
 314  * Only used internally at session destruction.
 315  */
 316 static
 317 void _lttng_event_unregister(struct lttng_event *event)
 318 {
 319         if (event->priv->registered)
 320                 unregister_event(event);
 321 }
 322
 323 /*
 324  * Only used internally at session destruction.
 325  */
 326 static
 327 void _lttng_event_notifier_unregister(struct lttng_event_notifier *event_notifier)
 328 {
 329         if (event_notifier->registered)
 330                 unregister_event_notifier(event_notifier);
 331 }
 332
 333 void lttng_session_destroy(struct lttng_session *session)
 334 {
 335         struct lttng_channel *chan, *tmpchan;
 336         struct lttng_ust_event_private *event_priv, *tmpevent_priv;
 337         struct lttng_enum *_enum, *tmp_enum;
 338         struct lttng_event_enabler *event_enabler, *event_tmpenabler;
 339
 340         CMM_ACCESS_ONCE(session->active) = 0;
 341         cds_list_for_each_entry(event_priv, &session->priv->events_head, node) {
 342                 _lttng_event_unregister(event_priv->pub);
 343         }
 344         lttng_ust_urcu_synchronize_rcu();       /* Wait for in-flight events to complete */
 345         __tracepoint_probe_prune_release_queue();
 346         cds_list_for_each_entry_safe(event_enabler, event_tmpenabler,
 347                         &session->priv->enablers_head, node)
 348                 lttng_event_enabler_destroy(event_enabler);
 349         cds_list_for_each_entry_safe(event_priv, tmpevent_priv,
 350                         &session->priv->events_head, node)
 351                 _lttng_event_destroy(event_priv->pub);
 352         cds_list_for_each_entry_safe(_enum, tmp_enum,
 353                         &session->priv->enums_head, node)
 354                 _lttng_enum_destroy(_enum);
 355         cds_list_for_each_entry_safe(chan, tmpchan, &session->priv->chan_head, node)
 356                 _lttng_channel_unmap(chan);
 357         cds_list_del(&session->priv->node);
 358         lttng_destroy_context(session->priv->ctx);
 359         free(session->priv);
 360         free(session);
 361 }
 362
 363 void lttng_event_notifier_group_destroy(
 364                 struct lttng_event_notifier_group *event_notifier_group)
 365 {
 366         int close_ret;
 367         struct lttng_event_notifier_enabler *notifier_enabler, *tmpnotifier_enabler;
 368         struct lttng_event_notifier *notifier, *tmpnotifier;
 369
 370         if (!event_notifier_group) {
 371                 return;
 372         }
 373
 374         cds_list_for_each_entry(notifier,
 375                         &event_notifier_group->event_notifiers_head, node)
 376                 _lttng_event_notifier_unregister(notifier);
 377
 378         lttng_ust_urcu_synchronize_rcu();
 379
 380         cds_list_for_each_entry_safe(notifier_enabler, tmpnotifier_enabler,
 381                         &event_notifier_group->enablers_head, node)
 382                 lttng_event_notifier_enabler_destroy(notifier_enabler);
 383
 384         cds_list_for_each_entry_safe(notifier, tmpnotifier,
 385                         &event_notifier_group->event_notifiers_head, node)
 386                 _lttng_event_notifier_destroy(notifier);
 387
 388         if (event_notifier_group->error_counter)
 389                 lttng_ust_counter_destroy(event_notifier_group->error_counter);
 390
 391         /* Close the notification fd to the listener of event_notifiers. */
 392
 393         lttng_ust_lock_fd_tracker();
 394         close_ret = close(event_notifier_group->notification_fd);
 395         if (!close_ret) {
 396                 lttng_ust_delete_fd_from_tracker(
 397                                 event_notifier_group->notification_fd);
 398         } else {
 399                 PERROR("close");
 400                 abort();
 401         }
 402         lttng_ust_unlock_fd_tracker();
 403
 404         cds_list_del(&event_notifier_group->node);
 405
 406         free(event_notifier_group);
 407 }
 408
 409 static
 410 void lttng_enabler_destroy(struct lttng_enabler *enabler)
 411 {
 412         struct lttng_ust_bytecode_node *filter_node, *tmp_filter_node;
 413         struct lttng_ust_excluder_node *excluder_node, *tmp_excluder_node;
 414
 415         if (!enabler) {
 416                 return;
 417         }
 418
 419         /* Destroy filter bytecode */
 420         cds_list_for_each_entry_safe(filter_node, tmp_filter_node,
 421                         &enabler->filter_bytecode_head, node) {
 422                 free(filter_node);
 423         }
 424
 425         /* Destroy excluders */
 426         cds_list_for_each_entry_safe(excluder_node, tmp_excluder_node,
 427                         &enabler->excluder_head, node) {
 428                 free(excluder_node);
 429         }
 430 }
 431
 432  void lttng_event_notifier_enabler_destroy(struct lttng_event_notifier_enabler *event_notifier_enabler)
 433 {
 434         if (!event_notifier_enabler) {
 435                 return;
 436         }
 437
 438         cds_list_del(&event_notifier_enabler->node);
 439
 440         lttng_enabler_destroy(lttng_event_notifier_enabler_as_enabler(event_notifier_enabler));
 441
 442         free(event_notifier_enabler);
 443 }
 444
 445 static
 446 int lttng_enum_create(const struct lttng_enum_desc *desc,
 447                 struct lttng_session *session)
 448 {
 449         const char *enum_name = desc->name;
 450         struct lttng_enum *_enum;
 451         struct cds_hlist_head *head;
 452         int ret = 0;
 453         size_t name_len = strlen(enum_name);
 454         uint32_t hash;
 455         int notify_socket;
 456
 457         /* Check if this enum is already registered for this session. */
 458         hash = jhash(enum_name, name_len, 0);
 459         head = &session->priv->enums_ht.table[hash & (LTTNG_UST_ENUM_HT_SIZE - 1)];
 460
 461         _enum = lttng_ust_enum_get_from_desc(session, desc);
 462         if (_enum) {
 463                 ret = -EEXIST;
 464                 goto exist;
 465         }
 466
 467         notify_socket = lttng_get_notify_socket(session->priv->owner);
 468         if (notify_socket < 0) {
 469                 ret = notify_socket;
 470                 goto socket_error;
 471         }
 472
 473         _enum = zmalloc(sizeof(*_enum));
 474         if (!_enum) {
 475                 ret = -ENOMEM;
 476                 goto cache_error;
 477         }
 478         _enum->session = session;
 479         _enum->desc = desc;
 480
 481         ret = ustcomm_register_enum(notify_socket,
 482                 session->priv->objd,
 483                 enum_name,
 484                 desc->nr_entries,
 485                 desc->entries,
 486                 &_enum->id);
 487         if (ret < 0) {
 488                 DBG("Error (%d) registering enumeration to sessiond", ret);
 489                 goto sessiond_register_error;
 490         }
 491         cds_list_add(&_enum->node, &session->priv->enums_head);
 492         cds_hlist_add_head(&_enum->hlist, head);
 493         return 0;
 494
 495 sessiond_register_error:
 496         free(_enum);
 497 cache_error:
 498 socket_error:
 499 exist:
 500         return ret;
 501 }
 502
 503 static
 504 int lttng_create_enum_check(const struct lttng_type *type,
 505                 struct lttng_session *session)
 506 {
 507         switch (type->atype) {
 508         case atype_enum:
 509         {
 510                 const struct lttng_enum_desc *enum_desc;
 511                 int ret;
 512
 513                 enum_desc = type->u.legacy.basic.enumeration.desc;
 514                 ret = lttng_enum_create(enum_desc, session);
 515                 if (ret && ret != -EEXIST) {
 516                         DBG("Unable to create enum error: (%d)", ret);
 517                         return ret;
 518                 }
 519                 break;
 520         }
 521         case atype_enum_nestable:
 522         {
 523                 const struct lttng_enum_desc *enum_desc;
 524                 int ret;
 525
 526                 enum_desc = type->u.enum_nestable.desc;
 527                 ret = lttng_enum_create(enum_desc, session);
 528                 if (ret && ret != -EEXIST) {
 529                         DBG("Unable to create enum error: (%d)", ret);
 530                         return ret;
 531                 }
 532                 break;
 533         }
 534         case atype_dynamic:
 535         {
 536                 const struct lttng_event_field *tag_field_generic;
 537                 const struct lttng_enum_desc *enum_desc;
 538                 int ret;
 539
 540                 tag_field_generic = lttng_ust_dynamic_type_tag_field();
 541                 enum_desc = tag_field_generic->type.u.enum_nestable.desc;
 542                 ret = lttng_enum_create(enum_desc, session);
 543                 if (ret && ret != -EEXIST) {
 544                         DBG("Unable to create enum error: (%d)", ret);
 545                         return ret;
 546                 }
 547                 break;
 548         }
 549         default:
 550                 /* TODO: nested types when they become supported. */
 551                 break;
 552         }
 553         return 0;
 554 }
 555
 556 static
 557 int lttng_create_all_event_enums(size_t nr_fields,
 558                 const struct lttng_event_field *event_fields,
 559                 struct lttng_session *session)
 560 {
 561         size_t i;
 562         int ret;
 563
 564         /* For each field, ensure enum is part of the session. */
 565         for (i = 0; i < nr_fields; i++) {
 566                 const struct lttng_type *type = &event_fields[i].type;
 567
 568                 ret = lttng_create_enum_check(type, session);
 569                 if (ret)
 570                         return ret;
 571         }
 572         return 0;
 573 }
 574
 575 static
 576 int lttng_create_all_ctx_enums(size_t nr_fields,
 577                 const struct lttng_ctx_field *ctx_fields,
 578                 struct lttng_session *session)
 579 {
 580         size_t i;
 581         int ret;
 582
 583         /* For each field, ensure enum is part of the session. */
 584         for (i = 0; i < nr_fields; i++) {
 585                 const struct lttng_type *type = &ctx_fields[i].event_field.type;
 586
 587                 ret = lttng_create_enum_check(type, session);
 588                 if (ret)
 589                         return ret;
 590         }
 591         return 0;
 592 }
 593
 594 /*
 595  * Ensure that a state-dump will be performed for this session at the end
 596  * of the current handle_message().
 597  */
 598 int lttng_session_statedump(struct lttng_session *session)
 599 {
 600         session->priv->statedump_pending = 1;
 601         lttng_ust_sockinfo_session_enabled(session->priv->owner);
 602         return 0;
 603 }
 604
 605 int lttng_session_enable(struct lttng_session *session)
 606 {
 607         int ret = 0;
 608         struct lttng_channel *chan;
 609         int notify_socket;
 610
 611         if (session->active) {
 612                 ret = -EBUSY;
 613                 goto end;
 614         }
 615
 616         notify_socket = lttng_get_notify_socket(session->priv->owner);
 617         if (notify_socket < 0)
 618                 return notify_socket;
 619
 620         /* Set transient enabler state to "enabled" */
 621         session->priv->tstate = 1;
 622
 623         /* We need to sync enablers with session before activation. */
 624         lttng_session_sync_event_enablers(session);
 625
 626         /*
 627          * Snapshot the number of events per channel to know the type of header
 628          * we need to use.
 629          */
 630         cds_list_for_each_entry(chan, &session->priv->chan_head, node) {
 631                 const struct lttng_ctx *ctx;
 632                 const struct lttng_ctx_field *fields = NULL;
 633                 size_t nr_fields = 0;
 634                 uint32_t chan_id;
 635
 636                 /* don't change it if session stop/restart */
 637                 if (chan->header_type)
 638                         continue;
 639                 ctx = chan->ctx;
 640                 if (ctx) {
 641                         nr_fields = ctx->nr_fields;
 642                         fields = ctx->fields;
 643                         ret = lttng_create_all_ctx_enums(nr_fields, fields,
 644                                 session);
 645                         if (ret < 0) {
 646                                 DBG("Error (%d) adding enum to session", ret);
 647                                 return ret;
 648                         }
 649                 }
 650                 ret = ustcomm_register_channel(notify_socket,
 651                         session,
 652                         session->priv->objd,
 653                         chan->objd,
 654                         nr_fields,
 655                         fields,
 656                         &chan_id,
 657                         &chan->header_type);
 658                 if (ret) {
 659                         DBG("Error (%d) registering channel to sessiond", ret);
 660                         return ret;
 661                 }
 662                 if (chan_id != chan->id) {
 663                         DBG("Error: channel registration id (%u) does not match id assigned at creation (%u)",
 664                                 chan_id, chan->id);
 665                         return -EINVAL;
 666                 }
 667         }
 668
 669         /* Set atomically the state to "active" */
 670         CMM_ACCESS_ONCE(session->active) = 1;
 671         CMM_ACCESS_ONCE(session->priv->been_active) = 1;
 672
 673         ret = lttng_session_statedump(session);
 674         if (ret)
 675                 return ret;
 676 end:
 677         return ret;
 678 }
 679
 680 int lttng_session_disable(struct lttng_session *session)
 681 {
 682         int ret = 0;
 683
 684         if (!session->active) {
 685                 ret = -EBUSY;
 686                 goto end;
 687         }
 688         /* Set atomically the state to "inactive" */
 689         CMM_ACCESS_ONCE(session->active) = 0;
 690
 691         /* Set transient enabler state to "disabled" */
 692         session->priv->tstate = 0;
 693         lttng_session_sync_event_enablers(session);
 694 end:
 695         return ret;
 696 }
 697
 698 int lttng_channel_enable(struct lttng_channel *channel)
 699 {
 700         int ret = 0;
 701
 702         if (channel->enabled) {
 703                 ret = -EBUSY;
 704                 goto end;
 705         }
 706         /* Set transient enabler state to "enabled" */
 707         channel->tstate = 1;
 708         lttng_session_sync_event_enablers(channel->session);
 709         /* Set atomically the state to "enabled" */
 710         CMM_ACCESS_ONCE(channel->enabled) = 1;
 711 end:
 712         return ret;
 713 }
 714
 715 int lttng_channel_disable(struct lttng_channel *channel)
 716 {
 717         int ret = 0;
 718
 719         if (!channel->enabled) {
 720                 ret = -EBUSY;
 721                 goto end;
 722         }
 723         /* Set atomically the state to "disabled" */
 724         CMM_ACCESS_ONCE(channel->enabled) = 0;
 725         /* Set transient enabler state to "enabled" */
 726         channel->tstate = 0;
 727         lttng_session_sync_event_enablers(channel->session);
 728 end:
 729         return ret;
 730 }
 731
 732 static inline
 733 struct cds_hlist_head *borrow_hash_table_bucket(
 734                 struct cds_hlist_head *hash_table,
 735                 unsigned int hash_table_size,
 736                 const struct lttng_event_desc *desc)
 737 {
 738         const char *event_name;
 739         size_t name_len;
 740         uint32_t hash;
 741
 742         event_name = desc->name;
 743         name_len = strlen(event_name);
 744
 745         hash = jhash(event_name, name_len, 0);
 746         return &hash_table[hash & (hash_table_size - 1)];
 747 }
 748
 749 /*
 750  * Supports event creation while tracing session is active.
 751  */
 752 static
 753 int lttng_event_create(const struct lttng_event_desc *desc,
 754                 struct lttng_channel *chan)
 755 {
 756         struct lttng_event *event;
 757         struct lttng_ust_event_private *event_priv;
 758         struct lttng_session *session = chan->session;
 759         struct cds_hlist_head *head;
 760         int ret = 0;
 761         int notify_socket, loglevel;
 762         const char *uri;
 763
 764         head = borrow_hash_table_bucket(chan->session->priv->events_ht.table,
 765                 LTTNG_UST_EVENT_HT_SIZE, desc);
 766
 767         notify_socket = lttng_get_notify_socket(session->priv->owner);
 768         if (notify_socket < 0) {
 769                 ret = notify_socket;
 770                 goto socket_error;
 771         }
 772
 773         ret = lttng_create_all_event_enums(desc->nr_fields, desc->fields,
 774                         session);
 775         if (ret < 0) {
 776                 DBG("Error (%d) adding enum to session", ret);
 777                 goto create_enum_error;
 778         }
 779
 780         /*
 781          * Check if loglevel match. Refuse to connect event if not.
 782          */
 783         event = zmalloc(sizeof(struct lttng_event));
 784         if (!event) {
 785                 ret = -ENOMEM;
 786                 goto cache_error;
 787         }
 788         event->struct_size = sizeof(struct lttng_event);
 789         event_priv = zmalloc(sizeof(struct lttng_ust_event_private));
 790         if (!event_priv) {
 791                 ret = -ENOMEM;
 792                 goto priv_error;
 793         }
 794         event->priv = event_priv;
 795         event_priv->pub = event;
 796         event->chan = chan;
 797
 798         /* Event will be enabled by enabler sync. */
 799         event->enabled = 0;
 800         event->priv->registered = 0;
 801         CDS_INIT_LIST_HEAD(&event->filter_bytecode_runtime_head);
 802         CDS_INIT_LIST_HEAD(&event->priv->enablers_ref_head);
 803         event->priv->desc = desc;
 804
 805         if (desc->loglevel)
 806                 loglevel = *(*event->priv->desc->loglevel);
 807         else
 808                 loglevel = TRACE_DEFAULT;
 809         if (desc->u.ext.model_emf_uri)
 810                 uri = *(desc->u.ext.model_emf_uri);
 811         else
 812                 uri = NULL;
 813
 814         /* Fetch event ID from sessiond */
 815         ret = ustcomm_register_event(notify_socket,
 816                 session,
 817                 session->priv->objd,
 818                 chan->objd,
 819                 desc->name,
 820                 loglevel,
 821                 desc->signature,
 822                 desc->nr_fields,
 823                 desc->fields,
 824                 uri,
 825                 &event->id);
 826         if (ret < 0) {
 827                 DBG("Error (%d) registering event to sessiond", ret);
 828                 goto sessiond_register_error;
 829         }
 830
 831         cds_list_add(&event->priv->node, &chan->session->priv->events_head);
 832         cds_hlist_add_head(&event->priv->hlist, head);
 833         return 0;
 834
 835 sessiond_register_error:
 836         free(event_priv);
 837 priv_error:
 838         free(event);
 839 cache_error:
 840 create_enum_error:
 841 socket_error:
 842         return ret;
 843 }
 844
 845 static
 846 int lttng_event_notifier_create(const struct lttng_event_desc *desc,
 847                 uint64_t token, uint64_t error_counter_index,
 848                 struct lttng_event_notifier_group *event_notifier_group)
 849 {
 850         struct lttng_event_notifier *event_notifier;
 851         struct cds_hlist_head *head;
 852         int ret = 0;
 853
 854         /*
 855          * Get the hashtable bucket the created lttng_event_notifier object
 856          * should be inserted.
 857          */
 858         head = borrow_hash_table_bucket(
 859                 event_notifier_group->event_notifiers_ht.table,
 860                 LTTNG_UST_EVENT_NOTIFIER_HT_SIZE, desc);
 861
 862         event_notifier = zmalloc(sizeof(struct lttng_event_notifier));
 863         if (!event_notifier) {
 864                 ret = -ENOMEM;
 865                 goto error;
 866         }
 867
 868         event_notifier->group = event_notifier_group;
 869         event_notifier->user_token = token;
 870         event_notifier->error_counter_index = error_counter_index;
 871
 872         /* Event notifier will be enabled by enabler sync. */
 873         event_notifier->enabled = 0;
 874         event_notifier->registered = 0;
 875
 876         CDS_INIT_LIST_HEAD(&event_notifier->filter_bytecode_runtime_head);
 877         CDS_INIT_LIST_HEAD(&event_notifier->capture_bytecode_runtime_head);
 878         CDS_INIT_LIST_HEAD(&event_notifier->enablers_ref_head);
 879         event_notifier->desc = desc;
 880         event_notifier->notification_send = lttng_event_notifier_notification_send;
 881
 882         cds_list_add(&event_notifier->node,
 883                         &event_notifier_group->event_notifiers_head);
 884         cds_hlist_add_head(&event_notifier->hlist, head);
 885
 886         return 0;
 887
 888 error:
 889         return ret;
 890 }
 891
 892 static
 893 void _lttng_event_notifier_destroy(struct lttng_event_notifier *event_notifier)
 894 {
 895         struct lttng_enabler_ref *enabler_ref, *tmp_enabler_ref;
 896
 897         /* Remove from event_notifier list. */
 898         cds_list_del(&event_notifier->node);
 899         /* Remove from event_notifier hash table. */
 900         cds_hlist_del(&event_notifier->hlist);
 901
 902         lttng_free_event_notifier_filter_runtime(event_notifier);
 903
 904         /* Free event_notifier enabler refs */
 905         cds_list_for_each_entry_safe(enabler_ref, tmp_enabler_ref,
 906                         &event_notifier->enablers_ref_head, node)
 907                 free(enabler_ref);
 908         free(event_notifier);
 909 }
 910
 911 static
 912 int lttng_desc_match_star_glob_enabler(const struct lttng_event_desc *desc,
 913                 struct lttng_enabler *enabler)
 914 {
 915         int loglevel = 0;
 916         unsigned int has_loglevel = 0;
 917
 918         assert(enabler->format_type == LTTNG_ENABLER_FORMAT_STAR_GLOB);
 919         if (!strutils_star_glob_match(enabler->event_param.name, SIZE_MAX,
 920                         desc->name, SIZE_MAX))
 921                 return 0;
 922         if (desc->loglevel) {
 923                 loglevel = *(*desc->loglevel);
 924                 has_loglevel = 1;
 925         }
 926         if (!lttng_loglevel_match(loglevel,
 927                         has_loglevel,
 928                         enabler->event_param.loglevel_type,
 929                         enabler->event_param.loglevel))
 930                 return 0;
 931         return 1;
 932 }
 933
 934 static
 935 int lttng_desc_match_event_enabler(const struct lttng_event_desc *desc,
 936                 struct lttng_enabler *enabler)
 937 {
 938         int loglevel = 0;
 939         unsigned int has_loglevel = 0;
 940
 941         assert(enabler->format_type == LTTNG_ENABLER_FORMAT_EVENT);
 942         if (strcmp(desc->name, enabler->event_param.name))
 943                 return 0;
 944         if (desc->loglevel) {
 945                 loglevel = *(*desc->loglevel);
 946                 has_loglevel = 1;
 947         }
 948         if (!lttng_loglevel_match(loglevel,
 949                         has_loglevel,
 950                         enabler->event_param.loglevel_type,
 951                         enabler->event_param.loglevel))
 952                 return 0;
 953         return 1;
 954 }
 955
 956 static
 957 int lttng_desc_match_enabler(const struct lttng_event_desc *desc,
 958                 struct lttng_enabler *enabler)
 959 {
 960         switch (enabler->format_type) {
 961         case LTTNG_ENABLER_FORMAT_STAR_GLOB:
 962         {
 963                 struct lttng_ust_excluder_node *excluder;
 964
 965                 if (!lttng_desc_match_star_glob_enabler(desc, enabler)) {
 966                         return 0;
 967                 }
 968
 969                 /*
 970                  * If the matching event matches with an excluder,
 971                  * return 'does not match'
 972                  */
 973                 cds_list_for_each_entry(excluder, &enabler->excluder_head, node) {
 974                         int count;
 975
 976                         for (count = 0; count < excluder->excluder.count; count++) {
 977                                 int len;
 978                                 char *excluder_name;
 979
 980                                 excluder_name = (char *) (excluder->excluder.names)
 981                                                 + count * LTTNG_UST_SYM_NAME_LEN;
 982                                 len = strnlen(excluder_name, LTTNG_UST_SYM_NAME_LEN);
 983                                 if (len > 0 && strutils_star_glob_match(excluder_name, len, desc->name, SIZE_MAX))
 984                                         return 0;
 985                         }
 986                 }
 987                 return 1;
 988         }
 989         case LTTNG_ENABLER_FORMAT_EVENT:
 990                 return lttng_desc_match_event_enabler(desc, enabler);
 991         default:
 992                 return -EINVAL;
 993         }
 994 }
 995
 996 static
 997 int lttng_event_enabler_match_event(struct lttng_event_enabler *event_enabler,
 998                 struct lttng_event *event)
 999 {
1000         if (lttng_desc_match_enabler(event->priv->desc,
1001                         lttng_event_enabler_as_enabler(event_enabler))
1002                         && event->chan == event_enabler->chan)
1003                 return 1;
1004         else
1005                 return 0;
1006 }
1007
1008 static
1009 int lttng_event_notifier_enabler_match_event_notifier(
1010                 struct lttng_event_notifier_enabler *event_notifier_enabler,
1011                 struct lttng_event_notifier *event_notifier)
1012 {
1013         int desc_matches = lttng_desc_match_enabler(event_notifier->desc,
1014                 lttng_event_notifier_enabler_as_enabler(event_notifier_enabler));
1015
1016         if (desc_matches && event_notifier->group == event_notifier_enabler->group &&
1017                         event_notifier->user_token == event_notifier_enabler->user_token)
1018                 return 1;
1019         else
1020                 return 0;
1021 }
1022
1023 static
1024 struct lttng_enabler_ref *lttng_enabler_ref(
1025                 struct cds_list_head *enabler_ref_list,
1026                 struct lttng_enabler *enabler)
1027 {
1028         struct lttng_enabler_ref *enabler_ref;
1029
1030         cds_list_for_each_entry(enabler_ref, enabler_ref_list, node) {
1031                 if (enabler_ref->ref == enabler)
1032                         return enabler_ref;
1033         }
1034         return NULL;
1035 }
1036
1037 /*
1038  * Create struct lttng_event if it is missing and present in the list of
1039  * tracepoint probes.
1040  */
1041 static
1042 void lttng_create_event_if_missing(struct lttng_event_enabler *event_enabler)
1043 {
1044         struct lttng_session *session = event_enabler->chan->session;
1045         struct lttng_probe_desc *probe_desc;
1046         const struct lttng_event_desc *desc;
1047         struct lttng_ust_event_private *event_priv;
1048         int i;
1049         struct cds_list_head *probe_list;
1050
1051         probe_list = lttng_get_probe_list_head();
1052         /*
1053          * For each probe event, if we find that a probe event matches
1054          * our enabler, create an associated lttng_event if not
1055          * already present.
1056          */
1057         cds_list_for_each_entry(probe_desc, probe_list, head) {
1058                 for (i = 0; i < probe_desc->nr_events; i++) {
1059                         int ret;
1060                         bool found = false;
1061                         struct cds_hlist_head *head;
1062                         struct cds_hlist_node *node;
1063
1064                         desc = probe_desc->event_desc[i];
1065                         if (!lttng_desc_match_enabler(desc,
1066                                         lttng_event_enabler_as_enabler(event_enabler)))
1067                                 continue;
1068
1069                         head = borrow_hash_table_bucket(
1070                                 session->priv->events_ht.table,
1071                                 LTTNG_UST_EVENT_HT_SIZE, desc);
1072
1073                         cds_hlist_for_each_entry(event_priv, node, head, hlist) {
1074                                 if (event_priv->desc == desc
1075                                                 && event_priv->pub->chan == event_enabler->chan) {
1076                                         found = true;
1077                                         break;
1078                                 }
1079                         }
1080                         if (found)
1081                                 continue;
1082
1083                         /*
1084                          * We need to create an event for this
1085                          * event probe.
1086                          */
1087                         ret = lttng_event_create(probe_desc->event_desc[i],
1088                                         event_enabler->chan);
1089                         if (ret) {
1090                                 DBG("Unable to create event %s, error %d\n",
1091                                         probe_desc->event_desc[i]->name, ret);
1092                         }
1093                 }
1094         }
1095 }
1096
1097 static
1098 void probe_provider_event_for_each(struct lttng_probe_desc *provider_desc,
1099                 void (*event_func)(struct lttng_session *session,
1100                         struct lttng_event *event),
1101                 void (*event_notifier_func)(struct lttng_event_notifier *event_notifier))
1102 {
1103         struct cds_hlist_node *node, *tmp_node;
1104         struct cds_list_head *sessionsp;
1105         unsigned int i;
1106
1107         /* Get handle on list of sessions. */
1108         sessionsp = lttng_get_sessions();
1109
1110         /*
1111          * Iterate over all events in the probe provider descriptions and
1112          * sessions to queue the unregistration of the events.
1113          */
1114         for (i = 0; i < provider_desc->nr_events; i++) {
1115                 const struct lttng_event_desc *event_desc;
1116                 struct lttng_event_notifier_group *event_notifier_group;
1117                 struct lttng_event_notifier *event_notifier;
1118                 struct lttng_ust_session_private *session_priv;
1119                 struct cds_hlist_head *head;
1120                 struct lttng_ust_event_private *event_priv;
1121
1122                 event_desc = provider_desc->event_desc[i];
1123
1124                 /*
1125                  * Iterate over all session to find the current event
1126                  * description.
1127                  */
1128                 cds_list_for_each_entry(session_priv, sessionsp, node) {
1129                         /*
1130                          * Get the list of events in the hashtable bucket and
1131                          * iterate to find the event matching this descriptor.
1132                          */
1133                         head = borrow_hash_table_bucket(
1134                                 session_priv->events_ht.table,
1135                                 LTTNG_UST_EVENT_HT_SIZE, event_desc);
1136
1137                         cds_hlist_for_each_entry_safe(event_priv, node, tmp_node, head, hlist) {
1138                                 if (event_desc == event_priv->desc) {
1139                                         event_func(session_priv->pub, event_priv->pub);
1140                                         break;
1141                                 }
1142                         }
1143                 }
1144
1145                 /*
1146                  * Iterate over all event_notifier groups to find the current event
1147                  * description.
1148                  */
1149                 cds_list_for_each_entry(event_notifier_group, &event_notifier_groups, node) {
1150                         /*
1151                          * Get the list of event_notifiers in the hashtable bucket and
1152                          * iterate to find the event_notifier matching this
1153                          * descriptor.
1154                          */
1155                         head = borrow_hash_table_bucket(
1156                                 event_notifier_group->event_notifiers_ht.table,
1157                                 LTTNG_UST_EVENT_NOTIFIER_HT_SIZE, event_desc);
1158
1159                         cds_hlist_for_each_entry_safe(event_notifier, node, tmp_node, head, hlist) {
1160                                 if (event_desc == event_notifier->desc) {
1161                                         event_notifier_func(event_notifier);
1162                                         break;
1163                                 }
1164                         }
1165                 }
1166         }
1167 }
1168
1169 static
1170 void _unregister_event(struct lttng_session *session,
1171                 struct lttng_event *event)
1172 {
1173         _lttng_event_unregister(event);
1174 }
1175
1176 static
1177 void _event_enum_destroy(struct lttng_session *session,
1178                 struct lttng_event *event)
1179 {
1180         unsigned int i;
1181
1182         /* Destroy enums of the current event. */
1183         for (i = 0; i < event->priv->desc->nr_fields; i++) {
1184                 const struct lttng_enum_desc *enum_desc;
1185                 const struct lttng_event_field *field;
1186                 struct lttng_enum *curr_enum;
1187
1188                 field = &(event->priv->desc->fields[i]);
1189                 switch (field->type.atype) {
1190                 case atype_enum:
1191                         enum_desc = field->type.u.legacy.basic.enumeration.desc;
1192                         break;
1193                 case atype_enum_nestable:
1194                         enum_desc = field->type.u.enum_nestable.desc;
1195                         break;
1196                 default:
1197                         continue;
1198                 }
1199
1200                 curr_enum = lttng_ust_enum_get_from_desc(session, enum_desc);
1201                 if (curr_enum) {
1202                         _lttng_enum_destroy(curr_enum);
1203                 }
1204         }
1205
1206         /* Destroy event. */
1207         _lttng_event_destroy(event);
1208 }
1209
1210 /*
1211  * Iterate over all the UST sessions to unregister and destroy all probes from
1212  * the probe provider descriptor received as argument. Must me called with the
1213  * ust_lock held.
1214  */
1215 void lttng_probe_provider_unregister_events(
1216                 struct lttng_probe_desc *provider_desc)
1217 {
1218         /*
1219          * Iterate over all events in the probe provider descriptions and sessions
1220          * to queue the unregistration of the events.
1221          */
1222         probe_provider_event_for_each(provider_desc, _unregister_event,
1223                 _lttng_event_notifier_unregister);
1224
1225         /* Wait for grace period. */
1226         lttng_ust_urcu_synchronize_rcu();
1227         /* Prune the unregistration queue. */
1228         __tracepoint_probe_prune_release_queue();
1229
1230         /*
1231          * It is now safe to destroy the events and remove them from the event list
1232          * and hashtables.
1233          */
1234         probe_provider_event_for_each(provider_desc, _event_enum_destroy,
1235                 _lttng_event_notifier_destroy);
1236 }
1237
1238 /*
1239  * Create events associated with an event enabler (if not already present),
1240  * and add backward reference from the event to the enabler.
1241  */
1242 static
1243 int lttng_event_enabler_ref_events(struct lttng_event_enabler *event_enabler)
1244 {
1245         struct lttng_session *session = event_enabler->chan->session;
1246         struct lttng_ust_event_private *event_priv;
1247
1248         if (!lttng_event_enabler_as_enabler(event_enabler)->enabled)
1249                 goto end;
1250
1251         /* First ensure that probe events are created for this enabler. */
1252         lttng_create_event_if_missing(event_enabler);
1253
1254         /* For each event matching enabler in session event list. */
1255         cds_list_for_each_entry(event_priv, &session->priv->events_head, node) {
1256                 struct lttng_enabler_ref *enabler_ref;
1257
1258                 if (!lttng_event_enabler_match_event(event_enabler, event_priv->pub))
1259                         continue;
1260
1261                 enabler_ref = lttng_enabler_ref(&event_priv->enablers_ref_head,
1262                         lttng_event_enabler_as_enabler(event_enabler));
1263                 if (!enabler_ref) {
1264                         /*
1265                          * If no backward ref, create it.
1266                          * Add backward ref from event to enabler.
1267                          */
1268                         enabler_ref = zmalloc(sizeof(*enabler_ref));
1269                         if (!enabler_ref)
1270                                 return -ENOMEM;
1271                         enabler_ref->ref = lttng_event_enabler_as_enabler(
1272                                 event_enabler);
1273                         cds_list_add(&enabler_ref->node,
1274                                 &event_priv->enablers_ref_head);
1275                 }
1276
1277                 /*
1278                  * Link filter bytecodes if not linked yet.
1279                  */
1280                 lttng_enabler_link_bytecode(event_priv->desc,
1281                         &session->priv->ctx,
1282                         &event_priv->pub->filter_bytecode_runtime_head,
1283                         &lttng_event_enabler_as_enabler(event_enabler)->filter_bytecode_head);
1284
1285                 /* TODO: merge event context. */
1286         }
1287 end:
1288         return 0;
1289 }
1290
1291 /*
1292  * Called at library load: connect the probe on all enablers matching
1293  * this event.
1294  * Called with session mutex held.
1295  */
1296 int lttng_fix_pending_events(void)
1297 {
1298         struct lttng_ust_session_private *session_priv;
1299
1300         cds_list_for_each_entry(session_priv, &sessions, node) {
1301                 lttng_session_lazy_sync_event_enablers(session_priv->pub);
1302         }
1303         return 0;
1304 }
1305
1306 int lttng_fix_pending_event_notifiers(void)
1307 {
1308         struct lttng_event_notifier_group *event_notifier_group;
1309
1310         cds_list_for_each_entry(event_notifier_group, &event_notifier_groups, node) {
1311                 lttng_event_notifier_group_sync_enablers(event_notifier_group);
1312         }
1313         return 0;
1314 }
1315
1316 /*
1317  * For each session of the owner thread, execute pending statedump.
1318  * Only dump state for the sessions owned by the caller thread, because
1319  * we don't keep ust_lock across the entire iteration.
1320  */
1321 void lttng_handle_pending_statedump(void *owner)
1322 {
1323         struct lttng_ust_session_private *session_priv;
1324
1325         /* Execute state dump */
1326         do_lttng_ust_statedump(owner);
1327
1328         /* Clear pending state dump */
1329         if (ust_lock()) {
1330                 goto end;
1331         }
1332         cds_list_for_each_entry(session_priv, &sessions, node) {
1333                 if (session_priv->owner != owner)
1334                         continue;
1335                 if (!session_priv->statedump_pending)
1336                         continue;
1337                 session_priv->statedump_pending = 0;
1338         }
1339 end:
1340         ust_unlock();
1341         return;
1342 }
1343
1344 /*
1345  * Only used internally at session destruction.
1346  */
1347 static
1348 void _lttng_event_destroy(struct lttng_event *event)
1349 {
1350         struct lttng_enabler_ref *enabler_ref, *tmp_enabler_ref;
1351
1352         /* Remove from event list. */
1353         cds_list_del(&event->priv->node);
1354         /* Remove from event hash table. */
1355         cds_hlist_del(&event->priv->hlist);
1356
1357         lttng_destroy_context(event->ctx);
1358         lttng_free_event_filter_runtime(event);
1359         /* Free event enabler refs */
1360         cds_list_for_each_entry_safe(enabler_ref, tmp_enabler_ref,
1361                         &event->priv->enablers_ref_head, node)
1362                 free(enabler_ref);
1363         free(event->priv);
1364         free(event);
1365 }
1366
1367 static
1368 void _lttng_enum_destroy(struct lttng_enum *_enum)
1369 {
1370         cds_list_del(&_enum->node);
1371         cds_hlist_del(&_enum->hlist);
1372         free(_enum);
1373 }
1374
1375 void lttng_ust_events_exit(void)
1376 {
1377         struct lttng_ust_session_private *session_priv, *tmpsession_priv;
1378
1379         cds_list_for_each_entry_safe(session_priv, tmpsession_priv, &sessions, node)
1380                 lttng_session_destroy(session_priv->pub);
1381 }
1382
1383 /*
1384  * Enabler management.
1385  */
1386 struct lttng_event_enabler *lttng_event_enabler_create(
1387                 enum lttng_enabler_format_type format_type,
1388                 struct lttng_ust_event *event_param,
1389                 struct lttng_channel *chan)
1390 {
1391         struct lttng_event_enabler *event_enabler;
1392
1393         event_enabler = zmalloc(sizeof(*event_enabler));
1394         if (!event_enabler)
1395                 return NULL;
1396         event_enabler->base.format_type = format_type;
1397         CDS_INIT_LIST_HEAD(&event_enabler->base.filter_bytecode_head);
1398         CDS_INIT_LIST_HEAD(&event_enabler->base.excluder_head);
1399         memcpy(&event_enabler->base.event_param, event_param,
1400                 sizeof(event_enabler->base.event_param));
1401         event_enabler->chan = chan;
1402         /* ctx left NULL */
1403         event_enabler->base.enabled = 0;
1404         cds_list_add(&event_enabler->node, &event_enabler->chan->session->priv->enablers_head);
1405         lttng_session_lazy_sync_event_enablers(event_enabler->chan->session);
1406
1407         return event_enabler;
1408 }
1409
1410 struct lttng_event_notifier_enabler *lttng_event_notifier_enabler_create(
1411                 struct lttng_event_notifier_group *event_notifier_group,
1412                 enum lttng_enabler_format_type format_type,
1413                 struct lttng_ust_event_notifier *event_notifier_param)
1414 {
1415         struct lttng_event_notifier_enabler *event_notifier_enabler;
1416
1417         event_notifier_enabler = zmalloc(sizeof(*event_notifier_enabler));
1418         if (!event_notifier_enabler)
1419                 return NULL;
1420         event_notifier_enabler->base.format_type = format_type;
1421         CDS_INIT_LIST_HEAD(&event_notifier_enabler->base.filter_bytecode_head);
1422         CDS_INIT_LIST_HEAD(&event_notifier_enabler->capture_bytecode_head);
1423         CDS_INIT_LIST_HEAD(&event_notifier_enabler->base.excluder_head);
1424
1425         event_notifier_enabler->user_token = event_notifier_param->event.token;
1426         event_notifier_enabler->error_counter_index = event_notifier_param->error_counter_index;
1427         event_notifier_enabler->num_captures = 0;
1428
1429         memcpy(&event_notifier_enabler->base.event_param.name,
1430                 event_notifier_param->event.name,
1431                 sizeof(event_notifier_enabler->base.event_param.name));
1432         event_notifier_enabler->base.event_param.instrumentation =
1433                 event_notifier_param->event.instrumentation;
1434         event_notifier_enabler->base.event_param.loglevel =
1435                 event_notifier_param->event.loglevel;
1436         event_notifier_enabler->base.event_param.loglevel_type =
1437                 event_notifier_param->event.loglevel_type;
1438
1439         event_notifier_enabler->base.enabled = 0;
1440         event_notifier_enabler->group = event_notifier_group;
1441
1442         cds_list_add(&event_notifier_enabler->node,
1443                         &event_notifier_group->enablers_head);
1444
1445         lttng_event_notifier_group_sync_enablers(event_notifier_group);
1446
1447         return event_notifier_enabler;
1448 }
1449
1450 int lttng_event_enabler_enable(struct lttng_event_enabler *event_enabler)
1451 {
1452         lttng_event_enabler_as_enabler(event_enabler)->enabled = 1;
1453         lttng_session_lazy_sync_event_enablers(event_enabler->chan->session);
1454
1455         return 0;
1456 }
1457
1458 int lttng_event_enabler_disable(struct lttng_event_enabler *event_enabler)
1459 {
1460         lttng_event_enabler_as_enabler(event_enabler)->enabled = 0;
1461         lttng_session_lazy_sync_event_enablers(event_enabler->chan->session);
1462
1463         return 0;
1464 }
1465
1466 static
1467 void _lttng_enabler_attach_filter_bytecode(struct lttng_enabler *enabler,
1468                 struct lttng_ust_bytecode_node **bytecode)
1469 {
1470         (*bytecode)->enabler = enabler;
1471         cds_list_add_tail(&(*bytecode)->node, &enabler->filter_bytecode_head);
1472         /* Take ownership of bytecode */
1473         *bytecode = NULL;
1474 }
1475
1476 int lttng_event_enabler_attach_filter_bytecode(struct lttng_event_enabler *event_enabler,
1477                 struct lttng_ust_bytecode_node **bytecode)
1478 {
1479         _lttng_enabler_attach_filter_bytecode(
1480                 lttng_event_enabler_as_enabler(event_enabler), bytecode);
1481
1482         lttng_session_lazy_sync_event_enablers(event_enabler->chan->session);
1483         return 0;
1484 }
1485
1486 static
1487 void _lttng_enabler_attach_exclusion(struct lttng_enabler *enabler,
1488                 struct lttng_ust_excluder_node **excluder)
1489 {
1490         (*excluder)->enabler = enabler;
1491         cds_list_add_tail(&(*excluder)->node, &enabler->excluder_head);
1492         /* Take ownership of excluder */
1493         *excluder = NULL;
1494 }
1495
1496 int lttng_event_enabler_attach_exclusion(struct lttng_event_enabler *event_enabler,
1497                 struct lttng_ust_excluder_node **excluder)
1498 {
1499         _lttng_enabler_attach_exclusion(
1500                 lttng_event_enabler_as_enabler(event_enabler), excluder);
1501
1502         lttng_session_lazy_sync_event_enablers(event_enabler->chan->session);
1503         return 0;
1504 }
1505
1506 int lttng_event_notifier_enabler_enable(
1507                 struct lttng_event_notifier_enabler *event_notifier_enabler)
1508 {
1509         lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->enabled = 1;
1510         lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
1511
1512         return 0;
1513 }
1514
1515 int lttng_event_notifier_enabler_disable(
1516                 struct lttng_event_notifier_enabler *event_notifier_enabler)
1517 {
1518         lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->enabled = 0;
1519         lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
1520
1521         return 0;
1522 }
1523
1524 int lttng_event_notifier_enabler_attach_filter_bytecode(
1525                 struct lttng_event_notifier_enabler *event_notifier_enabler,
1526                 struct lttng_ust_bytecode_node **bytecode)
1527 {
1528         _lttng_enabler_attach_filter_bytecode(
1529                 lttng_event_notifier_enabler_as_enabler(event_notifier_enabler),
1530                 bytecode);
1531
1532         lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
1533         return 0;
1534 }
1535
1536 int lttng_event_notifier_enabler_attach_capture_bytecode(
1537                 struct lttng_event_notifier_enabler *event_notifier_enabler,
1538                 struct lttng_ust_bytecode_node **bytecode)
1539 {
1540         (*bytecode)->enabler = lttng_event_notifier_enabler_as_enabler(
1541                         event_notifier_enabler);
1542         cds_list_add_tail(&(*bytecode)->node,
1543                         &event_notifier_enabler->capture_bytecode_head);
1544         /* Take ownership of bytecode */
1545         *bytecode = NULL;
1546         event_notifier_enabler->num_captures++;
1547
1548         lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
1549         return 0;
1550 }
1551
1552 int lttng_event_notifier_enabler_attach_exclusion(
1553                 struct lttng_event_notifier_enabler *event_notifier_enabler,
1554                 struct lttng_ust_excluder_node **excluder)
1555 {
1556         _lttng_enabler_attach_exclusion(
1557                 lttng_event_notifier_enabler_as_enabler(event_notifier_enabler),
1558                 excluder);
1559
1560         lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
1561         return 0;
1562 }
1563
1564 int lttng_attach_context(struct lttng_ust_context *context_param,
1565                 union ust_args *uargs,
1566                 struct lttng_ctx **ctx, struct lttng_session *session)
1567 {
1568         /*
1569          * We cannot attach a context after trace has been started for a
1570          * session because the metadata does not allow expressing this
1571          * information outside of the original channel scope.
1572          */
1573         if (session->priv->been_active)
1574                 return -EPERM;
1575
1576         switch (context_param->ctx) {
1577         case LTTNG_UST_CONTEXT_PTHREAD_ID:
1578                 return lttng_add_pthread_id_to_ctx(ctx);
1579         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
1580         {
1581                 struct lttng_ust_perf_counter_ctx *perf_ctx_param;
1582
1583                 perf_ctx_param = &context_param->u.perf_counter;
1584                 return lttng_add_perf_counter_to_ctx(
1585                         perf_ctx_param->type,
1586                         perf_ctx_param->config,
1587                         perf_ctx_param->name,
1588                         ctx);
1589         }
1590         case LTTNG_UST_CONTEXT_VTID:
1591                 return lttng_add_vtid_to_ctx(ctx);
1592         case LTTNG_UST_CONTEXT_VPID:
1593                 return lttng_add_vpid_to_ctx(ctx);
1594         case LTTNG_UST_CONTEXT_PROCNAME:
1595                 return lttng_add_procname_to_ctx(ctx);
1596         case LTTNG_UST_CONTEXT_IP:
1597                 return lttng_add_ip_to_ctx(ctx);
1598         case LTTNG_UST_CONTEXT_CPU_ID:
1599                 return lttng_add_cpu_id_to_ctx(ctx);
1600         case LTTNG_UST_CONTEXT_APP_CONTEXT:
1601                 return lttng_ust_add_app_context_to_ctx_rcu(uargs->app_context.ctxname,
1602                         ctx);
1603         case LTTNG_UST_CONTEXT_CGROUP_NS:
1604                 return lttng_add_cgroup_ns_to_ctx(ctx);
1605         case LTTNG_UST_CONTEXT_IPC_NS:
1606                 return lttng_add_ipc_ns_to_ctx(ctx);
1607         case LTTNG_UST_CONTEXT_MNT_NS:
1608                 return lttng_add_mnt_ns_to_ctx(ctx);
1609         case LTTNG_UST_CONTEXT_NET_NS:
1610                 return lttng_add_net_ns_to_ctx(ctx);
1611         case LTTNG_UST_CONTEXT_PID_NS:
1612                 return lttng_add_pid_ns_to_ctx(ctx);
1613         case LTTNG_UST_CONTEXT_TIME_NS:
1614                 return lttng_add_time_ns_to_ctx(ctx);
1615         case LTTNG_UST_CONTEXT_USER_NS:
1616                 return lttng_add_user_ns_to_ctx(ctx);
1617         case LTTNG_UST_CONTEXT_UTS_NS:
1618                 return lttng_add_uts_ns_to_ctx(ctx);
1619         case LTTNG_UST_CONTEXT_VUID:
1620                 return lttng_add_vuid_to_ctx(ctx);
1621         case LTTNG_UST_CONTEXT_VEUID:
1622                 return lttng_add_veuid_to_ctx(ctx);
1623         case LTTNG_UST_CONTEXT_VSUID:
1624                 return lttng_add_vsuid_to_ctx(ctx);
1625         case LTTNG_UST_CONTEXT_VGID:
1626                 return lttng_add_vgid_to_ctx(ctx);
1627         case LTTNG_UST_CONTEXT_VEGID:
1628                 return lttng_add_vegid_to_ctx(ctx);
1629         case LTTNG_UST_CONTEXT_VSGID:
1630                 return lttng_add_vsgid_to_ctx(ctx);
1631         default:
1632                 return -EINVAL;
1633         }
1634 }
1635
1636 int lttng_event_enabler_attach_context(struct lttng_event_enabler *enabler,
1637                 struct lttng_ust_context *context_param)
1638 {
1639         return -ENOSYS;
1640 }
1641
1642 void lttng_event_enabler_destroy(struct lttng_event_enabler *event_enabler)
1643 {
1644         if (!event_enabler) {
1645                 return;
1646         }
1647         cds_list_del(&event_enabler->node);
1648
1649         lttng_enabler_destroy(lttng_event_enabler_as_enabler(event_enabler));
1650
1651         lttng_destroy_context(event_enabler->ctx);
1652         free(event_enabler);
1653 }
1654
1655 /*
1656  * lttng_session_sync_event_enablers should be called just before starting a
1657  * session.
1658  */
1659 static
1660 void lttng_session_sync_event_enablers(struct lttng_session *session)
1661 {
1662         struct lttng_event_enabler *event_enabler;
1663         struct lttng_ust_event_private *event_priv;
1664
1665         cds_list_for_each_entry(event_enabler, &session->priv->enablers_head, node)
1666                 lttng_event_enabler_ref_events(event_enabler);
1667         /*
1668          * For each event, if at least one of its enablers is enabled,
1669          * and its channel and session transient states are enabled, we
1670          * enable the event, else we disable it.
1671          */
1672         cds_list_for_each_entry(event_priv, &session->priv->events_head, node) {
1673                 struct lttng_enabler_ref *enabler_ref;
1674                 struct lttng_bytecode_runtime *runtime;
1675                 int enabled = 0, has_enablers_without_bytecode = 0;
1676
1677                 /* Enable events */
1678                 cds_list_for_each_entry(enabler_ref,
1679                                 &event_priv->enablers_ref_head, node) {
1680                         if (enabler_ref->ref->enabled) {
1681                                 enabled = 1;
1682                                 break;
1683                         }
1684                 }
1685                 /*
1686                  * Enabled state is based on union of enablers, with
1687                  * intesection of session and channel transient enable
1688                  * states.
1689                  */
1690                 enabled = enabled && session->priv->tstate && event_priv->pub->chan->tstate;
1691
1692                 CMM_STORE_SHARED(event_priv->pub->enabled, enabled);
1693                 /*
1694                  * Sync tracepoint registration with event enabled
1695                  * state.
1696                  */
1697                 if (enabled) {
1698                         if (!event_priv->registered)
1699                                 register_event(event_priv->pub);
1700                 } else {
1701                         if (event_priv->registered)
1702                                 unregister_event(event_priv->pub);
1703                 }
1704
1705                 /* Check if has enablers without bytecode enabled */
1706                 cds_list_for_each_entry(enabler_ref,
1707                                 &event_priv->enablers_ref_head, node) {
1708                         if (enabler_ref->ref->enabled
1709                                         && cds_list_empty(&enabler_ref->ref->filter_bytecode_head)) {
1710                                 has_enablers_without_bytecode = 1;
1711                                 break;
1712                         }
1713                 }
1714                 event_priv->pub->has_enablers_without_bytecode =
1715                         has_enablers_without_bytecode;
1716
1717                 /* Enable filters */
1718                 cds_list_for_each_entry(runtime,
1719                                 &event_priv->pub->filter_bytecode_runtime_head, node) {
1720                         lttng_bytecode_filter_sync_state(runtime);
1721                 }
1722         }
1723         __tracepoint_probe_prune_release_queue();
1724 }
1725
1726 /* Support for event notifier is introduced by probe provider major version 2. */
1727 static
1728 bool lttng_ust_probe_supports_event_notifier(struct lttng_probe_desc *probe_desc)
1729 {
1730         return probe_desc->major >= 2;
1731 }
1732
1733 static
1734 void lttng_create_event_notifier_if_missing(
1735                 struct lttng_event_notifier_enabler *event_notifier_enabler)
1736 {
1737         struct lttng_event_notifier_group *event_notifier_group = event_notifier_enabler->group;
1738         struct lttng_probe_desc *probe_desc;
1739         struct cds_list_head *probe_list;
1740         int i;
1741
1742         probe_list = lttng_get_probe_list_head();
1743
1744         cds_list_for_each_entry(probe_desc, probe_list, head) {
1745                 for (i = 0; i < probe_desc->nr_events; i++) {
1746                         int ret;
1747                         bool found = false;
1748                         const struct lttng_event_desc *desc;
1749                         struct lttng_event_notifier *event_notifier;
1750                         struct cds_hlist_head *head;
1751                         struct cds_hlist_node *node;
1752
1753                         desc = probe_desc->event_desc[i];
1754
1755                         if (!lttng_desc_match_enabler(desc,
1756                                         lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)))
1757                                 continue;
1758
1759                         /*
1760                          * Given the current event_notifier group, get the bucket that
1761                          * the target event_notifier would be if it was already
1762                          * created.
1763                          */
1764                         head = borrow_hash_table_bucket(
1765                                 event_notifier_group->event_notifiers_ht.table,
1766                                 LTTNG_UST_EVENT_NOTIFIER_HT_SIZE, desc);
1767
1768                         cds_hlist_for_each_entry(event_notifier, node, head, hlist) {
1769                                 /*
1770                                  * Check if event_notifier already exists by checking
1771                                  * if the event_notifier and enabler share the same
1772                                  * description and id.
1773                                  */
1774                                 if (event_notifier->desc == desc &&
1775                                                 event_notifier->user_token == event_notifier_enabler->user_token) {
1776                                         found = true;
1777                                         break;
1778                                 }
1779                         }
1780
1781                         if (found)
1782                                 continue;
1783
1784                         /* Check that the probe supports event notifiers, else report the error. */
1785                         if (!lttng_ust_probe_supports_event_notifier(probe_desc)) {
1786                                 ERR("Probe \"%s\" contains event \"%s\" which matches an enabled event notifier, "
1787                                         "but its version (%u.%u) is too old and does not implement event notifiers. "
1788                                         "It needs to be recompiled against a newer version of LTTng-UST, otherwise "
1789                                         "this event will not generate any notification.",
1790                                         probe_desc->provider,
1791                                         desc->name,
1792                                         probe_desc->major,
1793                                         probe_desc->minor);
1794                                 continue;
1795                         }
1796                         /*
1797                          * We need to create a event_notifier for this event probe.
1798                          */
1799                         ret = lttng_event_notifier_create(desc,
1800                                 event_notifier_enabler->user_token,
1801                                 event_notifier_enabler->error_counter_index,
1802                                 event_notifier_group);
1803                         if (ret) {
1804                                 DBG("Unable to create event_notifier %s, error %d\n",
1805                                         probe_desc->event_desc[i]->name, ret);
1806                         }
1807                 }
1808         }
1809 }
1810
1811 /*
1812  * Create event_notifiers associated with a event_notifier enabler (if not already present).
1813  */
1814 static
1815 int lttng_event_notifier_enabler_ref_event_notifiers(
1816                 struct lttng_event_notifier_enabler *event_notifier_enabler)
1817 {
1818         struct lttng_event_notifier_group *event_notifier_group = event_notifier_enabler->group;
1819         struct lttng_event_notifier *event_notifier;
1820
1821          /*
1822           * Only try to create event_notifiers for enablers that are enabled, the user
1823           * might still be attaching filter or exclusion to the
1824           * event_notifier_enabler.
1825           */
1826         if (!lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->enabled)
1827                 goto end;
1828
1829         /* First, ensure that probe event_notifiers are created for this enabler. */
1830         lttng_create_event_notifier_if_missing(event_notifier_enabler);
1831
1832         /* Link the created event_notifier with its associated enabler. */
1833         cds_list_for_each_entry(event_notifier, &event_notifier_group->event_notifiers_head, node) {
1834                 struct lttng_enabler_ref *enabler_ref;
1835
1836                 if (!lttng_event_notifier_enabler_match_event_notifier(event_notifier_enabler, event_notifier))
1837                         continue;
1838
1839                 enabler_ref = lttng_enabler_ref(&event_notifier->enablers_ref_head,
1840                         lttng_event_notifier_enabler_as_enabler(event_notifier_enabler));
1841                 if (!enabler_ref) {
1842                         /*
1843                          * If no backward ref, create it.
1844                          * Add backward ref from event_notifier to enabler.
1845                          */
1846                         enabler_ref = zmalloc(sizeof(*enabler_ref));
1847                         if (!enabler_ref)
1848                                 return -ENOMEM;
1849
1850                         enabler_ref->ref = lttng_event_notifier_enabler_as_enabler(
1851                                 event_notifier_enabler);
1852                         cds_list_add(&enabler_ref->node,
1853                                 &event_notifier->enablers_ref_head);
1854                 }
1855
1856                 /*
1857                  * Link filter bytecodes if not linked yet.
1858                  */
1859                 lttng_enabler_link_bytecode(event_notifier->desc,
1860                         &event_notifier_group->ctx,
1861                         &event_notifier->filter_bytecode_runtime_head,
1862                         &lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->filter_bytecode_head);
1863
1864                 /*
1865                  * Link capture bytecodes if not linked yet.
1866                  */
1867                 lttng_enabler_link_bytecode(event_notifier->desc,
1868                         &event_notifier_group->ctx, &event_notifier->capture_bytecode_runtime_head,
1869                         &event_notifier_enabler->capture_bytecode_head);
1870
1871                 event_notifier->num_captures = event_notifier_enabler->num_captures;
1872         }
1873 end:
1874         return 0;
1875 }
1876
1877 static
1878 void lttng_event_notifier_group_sync_enablers(struct lttng_event_notifier_group *event_notifier_group)
1879 {
1880         struct lttng_event_notifier_enabler *event_notifier_enabler;
1881         struct lttng_event_notifier *event_notifier;
1882
1883         cds_list_for_each_entry(event_notifier_enabler, &event_notifier_group->enablers_head, node)
1884                 lttng_event_notifier_enabler_ref_event_notifiers(event_notifier_enabler);
1885
1886         /*
1887          * For each event_notifier, if at least one of its enablers is enabled,
1888          * we enable the event_notifier, else we disable it.
1889          */
1890         cds_list_for_each_entry(event_notifier, &event_notifier_group->event_notifiers_head, node) {
1891                 struct lttng_enabler_ref *enabler_ref;
1892                 struct lttng_bytecode_runtime *runtime;
1893                 int enabled = 0, has_enablers_without_bytecode = 0;
1894
1895                 /* Enable event_notifiers */
1896                 cds_list_for_each_entry(enabler_ref,
1897                                 &event_notifier->enablers_ref_head, node) {
1898                         if (enabler_ref->ref->enabled) {
1899                                 enabled = 1;
1900                                 break;
1901                         }
1902                 }
1903
1904                 CMM_STORE_SHARED(event_notifier->enabled, enabled);
1905                 /*
1906                  * Sync tracepoint registration with event_notifier enabled
1907                  * state.
1908                  */
1909                 if (enabled) {
1910                         if (!event_notifier->registered)
1911                                 register_event_notifier(event_notifier);
1912                 } else {
1913                         if (event_notifier->registered)
1914                                 unregister_event_notifier(event_notifier);
1915                 }
1916
1917                 /* Check if has enablers without bytecode enabled */
1918                 cds_list_for_each_entry(enabler_ref,
1919                                 &event_notifier->enablers_ref_head, node) {
1920                         if (enabler_ref->ref->enabled
1921                                         && cds_list_empty(&enabler_ref->ref->filter_bytecode_head)) {
1922                                 has_enablers_without_bytecode = 1;
1923                                 break;
1924                         }
1925                 }
1926                 event_notifier->has_enablers_without_bytecode =
1927                         has_enablers_without_bytecode;
1928
1929                 /* Enable filters */
1930                 cds_list_for_each_entry(runtime,
1931                                 &event_notifier->filter_bytecode_runtime_head, node) {
1932                         lttng_bytecode_filter_sync_state(runtime);
1933                 }
1934
1935                 /* Enable captures. */
1936                 cds_list_for_each_entry(runtime,
1937                                 &event_notifier->capture_bytecode_runtime_head, node) {
1938                         lttng_bytecode_capture_sync_state(runtime);
1939                 }
1940         }
1941         __tracepoint_probe_prune_release_queue();
1942 }
1943
1944 /*
1945  * Apply enablers to session events, adding events to session if need
1946  * be. It is required after each modification applied to an active
1947  * session, and right before session "start".
1948  * "lazy" sync means we only sync if required.
1949  */
1950 static
1951 void lttng_session_lazy_sync_event_enablers(struct lttng_session *session)
1952 {
1953         /* We can skip if session is not active */
1954         if (!session->active)
1955                 return;
1956         lttng_session_sync_event_enablers(session);
1957 }
1958
1959 /*
1960  * Update all sessions with the given app context.
1961  * Called with ust lock held.
1962  * This is invoked when an application context gets loaded/unloaded. It
1963  * ensures the context callbacks are in sync with the application
1964  * context (either app context callbacks, or dummy callbacks).
1965  */
1966 void lttng_ust_context_set_session_provider(const char *name,
1967                 size_t (*get_size)(struct lttng_ctx_field *field, size_t offset),
1968                 void (*record)(struct lttng_ctx_field *field,
1969                         struct lttng_ust_lib_ring_buffer_ctx *ctx,
1970                         struct lttng_channel *chan),
1971                 void (*get_value)(struct lttng_ctx_field *field,
1972                         struct lttng_ctx_value *value))
1973 {
1974         struct lttng_ust_session_private *session_priv;
1975
1976         cds_list_for_each_entry(session_priv, &sessions, node) {
1977                 struct lttng_channel *chan;
1978                 struct lttng_ust_event_private *event_priv;
1979                 int ret;
1980
1981                 ret = lttng_ust_context_set_provider_rcu(&session_priv->ctx,
1982                                 name, get_size, record, get_value);
1983                 if (ret)
1984                         abort();
1985                 cds_list_for_each_entry(chan, &session_priv->chan_head, node) {
1986                         ret = lttng_ust_context_set_provider_rcu(&chan->ctx,
1987                                         name, get_size, record, get_value);
1988                         if (ret)
1989                                 abort();
1990                 }
1991                 cds_list_for_each_entry(event_priv, &session_priv->events_head, node) {
1992                         ret = lttng_ust_context_set_provider_rcu(&event_priv->pub->ctx,
1993                                         name, get_size, record, get_value);
1994                         if (ret)
1995                                 abort();
1996                 }
1997         }
1998 }
1999
2000 /*
2001  * Update all event_notifier groups with the given app context.
2002  * Called with ust lock held.
2003  * This is invoked when an application context gets loaded/unloaded. It
2004  * ensures the context callbacks are in sync with the application
2005  * context (either app context callbacks, or dummy callbacks).
2006  */
2007 void lttng_ust_context_set_event_notifier_group_provider(const char *name,
2008                 size_t (*get_size)(struct lttng_ctx_field *field, size_t offset),
2009                 void (*record)(struct lttng_ctx_field *field,
2010                         struct lttng_ust_lib_ring_buffer_ctx *ctx,
2011                         struct lttng_channel *chan),
2012                 void (*get_value)(struct lttng_ctx_field *field,
2013                         struct lttng_ctx_value *value))
2014 {
2015         struct lttng_event_notifier_group *event_notifier_group;
2016
2017         cds_list_for_each_entry(event_notifier_group, &event_notifier_groups, node) {
2018                 int ret;
2019
2020                 ret = lttng_ust_context_set_provider_rcu(
2021                                 &event_notifier_group->ctx,
2022                                 name, get_size, record, get_value);
2023                 if (ret)
2024                         abort();
2025         }
2026 }