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