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