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_priv = zmalloc(sizeof(struct lttng_ust_event_private));
 788         if (!event_priv) {
 789                 ret = -ENOMEM;
 790                 goto priv_error;
 791         }
 792         event->priv = event_priv;
 793         event_priv->pub = event;
 794         event->chan = chan;
 795
 796         /* Event will be enabled by enabler sync. */
 797         event->enabled = 0;
 798         event->priv->registered = 0;
 799         CDS_INIT_LIST_HEAD(&event->filter_bytecode_runtime_head);
 800         CDS_INIT_LIST_HEAD(&event->priv->enablers_ref_head);
 801         event->priv->desc = desc;
 802
 803         if (desc->loglevel)
 804                 loglevel = *(*event->priv->desc->loglevel);
 805         else
 806                 loglevel = TRACE_DEFAULT;
 807         if (desc->u.ext.model_emf_uri)
 808                 uri = *(desc->u.ext.model_emf_uri);
 809         else
 810                 uri = NULL;
 811
 812         /* Fetch event ID from sessiond */
 813         ret = ustcomm_register_event(notify_socket,
 814                 session,
 815                 session->priv->objd,
 816                 chan->objd,
 817                 desc->name,
 818                 loglevel,
 819                 desc->signature,
 820                 desc->nr_fields,
 821                 desc->fields,
 822                 uri,
 823                 &event->id);
 824         if (ret < 0) {
 825                 DBG("Error (%d) registering event to sessiond", ret);
 826                 goto sessiond_register_error;
 827         }
 828
 829         cds_list_add(&event->priv->node, &chan->session->priv->events_head);
 830         cds_hlist_add_head(&event->priv->hlist, head);
 831         return 0;
 832
 833 sessiond_register_error:
 834         free(event_priv);
 835 priv_error:
 836         free(event);
 837 cache_error:
 838 create_enum_error:
 839 socket_error:
 840         return ret;
 841 }
 842
 843 static
 844 int lttng_event_notifier_create(const struct lttng_event_desc *desc,
 845                 uint64_t token, uint64_t error_counter_index,
 846                 struct lttng_event_notifier_group *event_notifier_group)
 847 {
 848         struct lttng_event_notifier *event_notifier;
 849         struct cds_hlist_head *head;
 850         int ret = 0;
 851
 852         /*
 853          * Get the hashtable bucket the created lttng_event_notifier object
 854          * should be inserted.
 855          */
 856         head = borrow_hash_table_bucket(
 857                 event_notifier_group->event_notifiers_ht.table,
 858                 LTTNG_UST_EVENT_NOTIFIER_HT_SIZE, desc);
 859
 860         event_notifier = zmalloc(sizeof(struct lttng_event_notifier));
 861         if (!event_notifier) {
 862                 ret = -ENOMEM;
 863                 goto error;
 864         }
 865
 866         event_notifier->group = event_notifier_group;
 867         event_notifier->user_token = token;
 868         event_notifier->error_counter_index = error_counter_index;
 869
 870         /* Event notifier will be enabled by enabler sync. */
 871         event_notifier->enabled = 0;
 872         event_notifier->registered = 0;
 873
 874         CDS_INIT_LIST_HEAD(&event_notifier->filter_bytecode_runtime_head);
 875         CDS_INIT_LIST_HEAD(&event_notifier->capture_bytecode_runtime_head);
 876         CDS_INIT_LIST_HEAD(&event_notifier->enablers_ref_head);
 877         event_notifier->desc = desc;
 878         event_notifier->notification_send = lttng_event_notifier_notification_send;
 879
 880         cds_list_add(&event_notifier->node,
 881                         &event_notifier_group->event_notifiers_head);
 882         cds_hlist_add_head(&event_notifier->hlist, head);
 883
 884         return 0;
 885
 886 error:
 887         return ret;
 888 }
 889
 890 static
 891 void _lttng_event_notifier_destroy(struct lttng_event_notifier *event_notifier)
 892 {
 893         struct lttng_enabler_ref *enabler_ref, *tmp_enabler_ref;
 894
 895         /* Remove from event_notifier list. */
 896         cds_list_del(&event_notifier->node);
 897         /* Remove from event_notifier hash table. */
 898         cds_hlist_del(&event_notifier->hlist);
 899
 900         lttng_free_event_notifier_filter_runtime(event_notifier);
 901
 902         /* Free event_notifier enabler refs */
 903         cds_list_for_each_entry_safe(enabler_ref, tmp_enabler_ref,
 904                         &event_notifier->enablers_ref_head, node)
 905                 free(enabler_ref);
 906         free(event_notifier);
 907 }
 908
 909 static
 910 int lttng_desc_match_star_glob_enabler(const struct lttng_event_desc *desc,
 911                 struct lttng_enabler *enabler)
 912 {
 913         int loglevel = 0;
 914         unsigned int has_loglevel = 0;
 915
 916         assert(enabler->format_type == LTTNG_ENABLER_FORMAT_STAR_GLOB);
 917         if (!strutils_star_glob_match(enabler->event_param.name, SIZE_MAX,
 918                         desc->name, SIZE_MAX))
 919                 return 0;
 920         if (desc->loglevel) {
 921                 loglevel = *(*desc->loglevel);
 922                 has_loglevel = 1;
 923         }
 924         if (!lttng_loglevel_match(loglevel,
 925                         has_loglevel,
 926                         enabler->event_param.loglevel_type,
 927                         enabler->event_param.loglevel))
 928                 return 0;
 929         return 1;
 930 }
 931
 932 static
 933 int lttng_desc_match_event_enabler(const struct lttng_event_desc *desc,
 934                 struct lttng_enabler *enabler)
 935 {
 936         int loglevel = 0;
 937         unsigned int has_loglevel = 0;
 938
 939         assert(enabler->format_type == LTTNG_ENABLER_FORMAT_EVENT);
 940         if (strcmp(desc->name, enabler->event_param.name))
 941                 return 0;
 942         if (desc->loglevel) {
 943                 loglevel = *(*desc->loglevel);
 944                 has_loglevel = 1;
 945         }
 946         if (!lttng_loglevel_match(loglevel,
 947                         has_loglevel,
 948                         enabler->event_param.loglevel_type,
 949                         enabler->event_param.loglevel))
 950                 return 0;
 951         return 1;
 952 }
 953
 954 static
 955 int lttng_desc_match_enabler(const struct lttng_event_desc *desc,
 956                 struct lttng_enabler *enabler)
 957 {
 958         switch (enabler->format_type) {
 959         case LTTNG_ENABLER_FORMAT_STAR_GLOB:
 960         {
 961                 struct lttng_ust_excluder_node *excluder;
 962
 963                 if (!lttng_desc_match_star_glob_enabler(desc, enabler)) {
 964                         return 0;
 965                 }
 966
 967                 /*
 968                  * If the matching event matches with an excluder,
 969                  * return 'does not match'
 970                  */
 971                 cds_list_for_each_entry(excluder, &enabler->excluder_head, node) {
 972                         int count;
 973
 974                         for (count = 0; count < excluder->excluder.count; count++) {
 975                                 int len;
 976                                 char *excluder_name;
 977
 978                                 excluder_name = (char *) (excluder->excluder.names)
 979                                                 + count * LTTNG_UST_SYM_NAME_LEN;
 980                                 len = strnlen(excluder_name, LTTNG_UST_SYM_NAME_LEN);
 981                                 if (len > 0 && strutils_star_glob_match(excluder_name, len, desc->name, SIZE_MAX))
 982                                         return 0;
 983                         }
 984                 }
 985                 return 1;
 986         }
 987         case LTTNG_ENABLER_FORMAT_EVENT:
 988                 return lttng_desc_match_event_enabler(desc, enabler);
 989         default:
 990                 return -EINVAL;
 991         }
 992 }
 993
 994 static
 995 int lttng_event_enabler_match_event(struct lttng_event_enabler *event_enabler,
 996                 struct lttng_event *event)
 997 {
 998         if (lttng_desc_match_enabler(event->priv->desc,
 999                         lttng_event_enabler_as_enabler(event_enabler))
1000                         && event->chan == event_enabler->chan)
1001                 return 1;
1002         else
1003                 return 0;
1004 }
1005
1006 static
1007 int lttng_event_notifier_enabler_match_event_notifier(
1008                 struct lttng_event_notifier_enabler *event_notifier_enabler,
1009                 struct lttng_event_notifier *event_notifier)
1010 {
1011         int desc_matches = lttng_desc_match_enabler(event_notifier->desc,
1012                 lttng_event_notifier_enabler_as_enabler(event_notifier_enabler));
1013
1014         if (desc_matches && event_notifier->group == event_notifier_enabler->group &&
1015                         event_notifier->user_token == event_notifier_enabler->user_token)
1016                 return 1;
1017         else
1018                 return 0;
1019 }
1020
1021 static
1022 struct lttng_enabler_ref *lttng_enabler_ref(
1023                 struct cds_list_head *enabler_ref_list,
1024                 struct lttng_enabler *enabler)
1025 {
1026         struct lttng_enabler_ref *enabler_ref;
1027
1028         cds_list_for_each_entry(enabler_ref, enabler_ref_list, node) {
1029                 if (enabler_ref->ref == enabler)
1030                         return enabler_ref;
1031         }
1032         return NULL;
1033 }
1034
1035 /*
1036  * Create struct lttng_event if it is missing and present in the list of
1037  * tracepoint probes.
1038  */
1039 static
1040 void lttng_create_event_if_missing(struct lttng_event_enabler *event_enabler)
1041 {
1042         struct lttng_session *session = event_enabler->chan->session;
1043         struct lttng_probe_desc *probe_desc;
1044         const struct lttng_event_desc *desc;
1045         struct lttng_ust_event_private *event_priv;
1046         int i;
1047         struct cds_list_head *probe_list;
1048
1049         probe_list = lttng_get_probe_list_head();
1050         /*
1051          * For each probe event, if we find that a probe event matches
1052          * our enabler, create an associated lttng_event if not
1053          * already present.
1054          */
1055         cds_list_for_each_entry(probe_desc, probe_list, head) {
1056                 for (i = 0; i < probe_desc->nr_events; i++) {
1057                         int ret;
1058                         bool found = false;
1059                         struct cds_hlist_head *head;
1060                         struct cds_hlist_node *node;
1061
1062                         desc = probe_desc->event_desc[i];
1063                         if (!lttng_desc_match_enabler(desc,
1064                                         lttng_event_enabler_as_enabler(event_enabler)))
1065                                 continue;
1066
1067                         head = borrow_hash_table_bucket(
1068                                 session->priv->events_ht.table,
1069                                 LTTNG_UST_EVENT_HT_SIZE, desc);
1070
1071                         cds_hlist_for_each_entry(event_priv, node, head, hlist) {
1072                                 if (event_priv->desc == desc
1073                                                 && event_priv->pub->chan == event_enabler->chan) {
1074                                         found = true;
1075                                         break;
1076                                 }
1077                         }
1078                         if (found)
1079                                 continue;
1080
1081                         /*
1082                          * We need to create an event for this
1083                          * event probe.
1084                          */
1085                         ret = lttng_event_create(probe_desc->event_desc[i],
1086                                         event_enabler->chan);
1087                         if (ret) {
1088                                 DBG("Unable to create event %s, error %d\n",
1089                                         probe_desc->event_desc[i]->name, ret);
1090                         }
1091                 }
1092         }
1093 }
1094
1095 static
1096 void probe_provider_event_for_each(struct lttng_probe_desc *provider_desc,
1097                 void (*event_func)(struct lttng_session *session,
1098                         struct lttng_event *event),
1099                 void (*event_notifier_func)(struct lttng_event_notifier *event_notifier))
1100 {
1101         struct cds_hlist_node *node, *tmp_node;
1102         struct cds_list_head *sessionsp;
1103         unsigned int i;
1104
1105         /* Get handle on list of sessions. */
1106         sessionsp = lttng_get_sessions();
1107
1108         /*
1109          * Iterate over all events in the probe provider descriptions and
1110          * sessions to queue the unregistration of the events.
1111          */
1112         for (i = 0; i < provider_desc->nr_events; i++) {
1113                 const struct lttng_event_desc *event_desc;
1114                 struct lttng_event_notifier_group *event_notifier_group;
1115                 struct lttng_event_notifier *event_notifier;
1116                 struct lttng_ust_session_private *session_priv;
1117                 struct cds_hlist_head *head;
1118                 struct lttng_ust_event_private *event_priv;
1119
1120                 event_desc = provider_desc->event_desc[i];
1121
1122                 /*
1123                  * Iterate over all session to find the current event
1124                  * description.
1125                  */
1126                 cds_list_for_each_entry(session_priv, sessionsp, node) {
1127                         /*
1128                          * Get the list of events in the hashtable bucket and
1129                          * iterate to find the event matching this descriptor.
1130                          */
1131                         head = borrow_hash_table_bucket(
1132                                 session_priv->events_ht.table,
1133                                 LTTNG_UST_EVENT_HT_SIZE, event_desc);
1134
1135                         cds_hlist_for_each_entry_safe(event_priv, node, tmp_node, head, hlist) {
1136                                 if (event_desc == event_priv->desc) {
1137                                         event_func(session_priv->pub, event_priv->pub);
1138                                         break;
1139                                 }
1140                         }
1141                 }
1142
1143                 /*
1144                  * Iterate over all event_notifier groups to find the current event
1145                  * description.
1146                  */
1147                 cds_list_for_each_entry(event_notifier_group, &event_notifier_groups, node) {
1148                         /*
1149                          * Get the list of event_notifiers in the hashtable bucket and
1150                          * iterate to find the event_notifier matching this
1151                          * descriptor.
1152                          */
1153                         head = borrow_hash_table_bucket(
1154                                 event_notifier_group->event_notifiers_ht.table,
1155                                 LTTNG_UST_EVENT_NOTIFIER_HT_SIZE, event_desc);
1156
1157                         cds_hlist_for_each_entry_safe(event_notifier, node, tmp_node, head, hlist) {
1158                                 if (event_desc == event_notifier->desc) {
1159                                         event_notifier_func(event_notifier);
1160                                         break;
1161                                 }
1162                         }
1163                 }
1164         }
1165 }
1166
1167 static
1168 void _unregister_event(struct lttng_session *session,
1169                 struct lttng_event *event)
1170 {
1171         _lttng_event_unregister(event);
1172 }
1173
1174 static
1175 void _event_enum_destroy(struct lttng_session *session,
1176                 struct lttng_event *event)
1177 {
1178         unsigned int i;
1179
1180         /* Destroy enums of the current event. */
1181         for (i = 0; i < event->priv->desc->nr_fields; i++) {
1182                 const struct lttng_enum_desc *enum_desc;
1183                 const struct lttng_event_field *field;
1184                 struct lttng_enum *curr_enum;
1185
1186                 field = &(event->priv->desc->fields[i]);
1187                 switch (field->type.atype) {
1188                 case atype_enum:
1189                         enum_desc = field->type.u.legacy.basic.enumeration.desc;
1190                         break;
1191                 case atype_enum_nestable:
1192                         enum_desc = field->type.u.enum_nestable.desc;
1193                         break;
1194                 default:
1195                         continue;
1196                 }
1197
1198                 curr_enum = lttng_ust_enum_get_from_desc(session, enum_desc);
1199                 if (curr_enum) {
1200                         _lttng_enum_destroy(curr_enum);
1201                 }
1202         }
1203
1204         /* Destroy event. */
1205         _lttng_event_destroy(event);
1206 }
1207
1208 /*
1209  * Iterate over all the UST sessions to unregister and destroy all probes from
1210  * the probe provider descriptor received as argument. Must me called with the
1211  * ust_lock held.
1212  */
1213 void lttng_probe_provider_unregister_events(
1214                 struct lttng_probe_desc *provider_desc)
1215 {
1216         /*
1217          * Iterate over all events in the probe provider descriptions and sessions
1218          * to queue the unregistration of the events.
1219          */
1220         probe_provider_event_for_each(provider_desc, _unregister_event,
1221                 _lttng_event_notifier_unregister);
1222
1223         /* Wait for grace period. */
1224         lttng_ust_urcu_synchronize_rcu();
1225         /* Prune the unregistration queue. */
1226         __tracepoint_probe_prune_release_queue();
1227
1228         /*
1229          * It is now safe to destroy the events and remove them from the event list
1230          * and hashtables.
1231          */
1232         probe_provider_event_for_each(provider_desc, _event_enum_destroy,
1233                 _lttng_event_notifier_destroy);
1234 }
1235
1236 /*
1237  * Create events associated with an event enabler (if not already present),
1238  * and add backward reference from the event to the enabler.
1239  */
1240 static
1241 int lttng_event_enabler_ref_events(struct lttng_event_enabler *event_enabler)
1242 {
1243         struct lttng_session *session = event_enabler->chan->session;
1244         struct lttng_ust_event_private *event_priv;
1245
1246         if (!lttng_event_enabler_as_enabler(event_enabler)->enabled)
1247                 goto end;
1248
1249         /* First ensure that probe events are created for this enabler. */
1250         lttng_create_event_if_missing(event_enabler);
1251
1252         /* For each event matching enabler in session event list. */
1253         cds_list_for_each_entry(event_priv, &session->priv->events_head, node) {
1254                 struct lttng_enabler_ref *enabler_ref;
1255
1256                 if (!lttng_event_enabler_match_event(event_enabler, event_priv->pub))
1257                         continue;
1258
1259                 enabler_ref = lttng_enabler_ref(&event_priv->enablers_ref_head,
1260                         lttng_event_enabler_as_enabler(event_enabler));
1261                 if (!enabler_ref) {
1262                         /*
1263                          * If no backward ref, create it.
1264                          * Add backward ref from event to enabler.
1265                          */
1266                         enabler_ref = zmalloc(sizeof(*enabler_ref));
1267                         if (!enabler_ref)
1268                                 return -ENOMEM;
1269                         enabler_ref->ref = lttng_event_enabler_as_enabler(
1270                                 event_enabler);
1271                         cds_list_add(&enabler_ref->node,
1272                                 &event_priv->enablers_ref_head);
1273                 }
1274
1275                 /*
1276                  * Link filter bytecodes if not linked yet.
1277                  */
1278                 lttng_enabler_link_bytecode(event_priv->desc,
1279                         &session->priv->ctx,
1280                         &event_priv->pub->filter_bytecode_runtime_head,
1281                         &lttng_event_enabler_as_enabler(event_enabler)->filter_bytecode_head);
1282
1283                 /* TODO: merge event context. */
1284         }
1285 end:
1286         return 0;
1287 }
1288
1289 /*
1290  * Called at library load: connect the probe on all enablers matching
1291  * this event.
1292  * Called with session mutex held.
1293  */
1294 int lttng_fix_pending_events(void)
1295 {
1296         struct lttng_ust_session_private *session_priv;
1297
1298         cds_list_for_each_entry(session_priv, &sessions, node) {
1299                 lttng_session_lazy_sync_event_enablers(session_priv->pub);
1300         }
1301         return 0;
1302 }
1303
1304 int lttng_fix_pending_event_notifiers(void)
1305 {
1306         struct lttng_event_notifier_group *event_notifier_group;
1307
1308         cds_list_for_each_entry(event_notifier_group, &event_notifier_groups, node) {
1309                 lttng_event_notifier_group_sync_enablers(event_notifier_group);
1310         }
1311         return 0;
1312 }
1313
1314 /*
1315  * For each session of the owner thread, execute pending statedump.
1316  * Only dump state for the sessions owned by the caller thread, because
1317  * we don't keep ust_lock across the entire iteration.
1318  */
1319 void lttng_handle_pending_statedump(void *owner)
1320 {
1321         struct lttng_ust_session_private *session_priv;
1322
1323         /* Execute state dump */
1324         do_lttng_ust_statedump(owner);
1325
1326         /* Clear pending state dump */
1327         if (ust_lock()) {
1328                 goto end;
1329         }
1330         cds_list_for_each_entry(session_priv, &sessions, node) {
1331                 if (session_priv->owner != owner)
1332                         continue;
1333                 if (!session_priv->statedump_pending)
1334                         continue;
1335                 session_priv->statedump_pending = 0;
1336         }
1337 end:
1338         ust_unlock();
1339         return;
1340 }
1341
1342 /*
1343  * Only used internally at session destruction.
1344  */
1345 static
1346 void _lttng_event_destroy(struct lttng_event *event)
1347 {
1348         struct lttng_enabler_ref *enabler_ref, *tmp_enabler_ref;
1349
1350         /* Remove from event list. */
1351         cds_list_del(&event->priv->node);
1352         /* Remove from event hash table. */
1353         cds_hlist_del(&event->priv->hlist);
1354
1355         lttng_destroy_context(event->ctx);
1356         lttng_free_event_filter_runtime(event);
1357         /* Free event enabler refs */
1358         cds_list_for_each_entry_safe(enabler_ref, tmp_enabler_ref,
1359                         &event->priv->enablers_ref_head, node)
1360                 free(enabler_ref);
1361         free(event->priv);
1362         free(event);
1363 }
1364
1365 static
1366 void _lttng_enum_destroy(struct lttng_enum *_enum)
1367 {
1368         cds_list_del(&_enum->node);
1369         cds_hlist_del(&_enum->hlist);
1370         free(_enum);
1371 }
1372
1373 void lttng_ust_events_exit(void)
1374 {
1375         struct lttng_ust_session_private *session_priv, *tmpsession_priv;
1376
1377         cds_list_for_each_entry_safe(session_priv, tmpsession_priv, &sessions, node)
1378                 lttng_session_destroy(session_priv->pub);
1379 }
1380
1381 /*
1382  * Enabler management.
1383  */
1384 struct lttng_event_enabler *lttng_event_enabler_create(
1385                 enum lttng_enabler_format_type format_type,
1386                 struct lttng_ust_event *event_param,
1387                 struct lttng_channel *chan)
1388 {
1389         struct lttng_event_enabler *event_enabler;
1390
1391         event_enabler = zmalloc(sizeof(*event_enabler));
1392         if (!event_enabler)
1393                 return NULL;
1394         event_enabler->base.format_type = format_type;
1395         CDS_INIT_LIST_HEAD(&event_enabler->base.filter_bytecode_head);
1396         CDS_INIT_LIST_HEAD(&event_enabler->base.excluder_head);
1397         memcpy(&event_enabler->base.event_param, event_param,
1398                 sizeof(event_enabler->base.event_param));
1399         event_enabler->chan = chan;
1400         /* ctx left NULL */
1401         event_enabler->base.enabled = 0;
1402         cds_list_add(&event_enabler->node, &event_enabler->chan->session->priv->enablers_head);
1403         lttng_session_lazy_sync_event_enablers(event_enabler->chan->session);
1404
1405         return event_enabler;
1406 }
1407
1408 struct lttng_event_notifier_enabler *lttng_event_notifier_enabler_create(
1409                 struct lttng_event_notifier_group *event_notifier_group,
1410                 enum lttng_enabler_format_type format_type,
1411                 struct lttng_ust_event_notifier *event_notifier_param)
1412 {
1413         struct lttng_event_notifier_enabler *event_notifier_enabler;
1414
1415         event_notifier_enabler = zmalloc(sizeof(*event_notifier_enabler));
1416         if (!event_notifier_enabler)
1417                 return NULL;
1418         event_notifier_enabler->base.format_type = format_type;
1419         CDS_INIT_LIST_HEAD(&event_notifier_enabler->base.filter_bytecode_head);
1420         CDS_INIT_LIST_HEAD(&event_notifier_enabler->capture_bytecode_head);
1421         CDS_INIT_LIST_HEAD(&event_notifier_enabler->base.excluder_head);
1422
1423         event_notifier_enabler->user_token = event_notifier_param->event.token;
1424         event_notifier_enabler->error_counter_index = event_notifier_param->error_counter_index;
1425         event_notifier_enabler->num_captures = 0;
1426
1427         memcpy(&event_notifier_enabler->base.event_param.name,
1428                 event_notifier_param->event.name,
1429                 sizeof(event_notifier_enabler->base.event_param.name));
1430         event_notifier_enabler->base.event_param.instrumentation =
1431                 event_notifier_param->event.instrumentation;
1432         event_notifier_enabler->base.event_param.loglevel =
1433                 event_notifier_param->event.loglevel;
1434         event_notifier_enabler->base.event_param.loglevel_type =
1435                 event_notifier_param->event.loglevel_type;
1436
1437         event_notifier_enabler->base.enabled = 0;
1438         event_notifier_enabler->group = event_notifier_group;
1439
1440         cds_list_add(&event_notifier_enabler->node,
1441                         &event_notifier_group->enablers_head);
1442
1443         lttng_event_notifier_group_sync_enablers(event_notifier_group);
1444
1445         return event_notifier_enabler;
1446 }
1447
1448 int lttng_event_enabler_enable(struct lttng_event_enabler *event_enabler)
1449 {
1450         lttng_event_enabler_as_enabler(event_enabler)->enabled = 1;
1451         lttng_session_lazy_sync_event_enablers(event_enabler->chan->session);
1452
1453         return 0;
1454 }
1455
1456 int lttng_event_enabler_disable(struct lttng_event_enabler *event_enabler)
1457 {
1458         lttng_event_enabler_as_enabler(event_enabler)->enabled = 0;
1459         lttng_session_lazy_sync_event_enablers(event_enabler->chan->session);
1460
1461         return 0;
1462 }
1463
1464 static
1465 void _lttng_enabler_attach_filter_bytecode(struct lttng_enabler *enabler,
1466                 struct lttng_ust_bytecode_node **bytecode)
1467 {
1468         (*bytecode)->enabler = enabler;
1469         cds_list_add_tail(&(*bytecode)->node, &enabler->filter_bytecode_head);
1470         /* Take ownership of bytecode */
1471         *bytecode = NULL;
1472 }
1473
1474 int lttng_event_enabler_attach_filter_bytecode(struct lttng_event_enabler *event_enabler,
1475                 struct lttng_ust_bytecode_node **bytecode)
1476 {
1477         _lttng_enabler_attach_filter_bytecode(
1478                 lttng_event_enabler_as_enabler(event_enabler), bytecode);
1479
1480         lttng_session_lazy_sync_event_enablers(event_enabler->chan->session);
1481         return 0;
1482 }
1483
1484 static
1485 void _lttng_enabler_attach_exclusion(struct lttng_enabler *enabler,
1486                 struct lttng_ust_excluder_node **excluder)
1487 {
1488         (*excluder)->enabler = enabler;
1489         cds_list_add_tail(&(*excluder)->node, &enabler->excluder_head);
1490         /* Take ownership of excluder */
1491         *excluder = NULL;
1492 }
1493
1494 int lttng_event_enabler_attach_exclusion(struct lttng_event_enabler *event_enabler,
1495                 struct lttng_ust_excluder_node **excluder)
1496 {
1497         _lttng_enabler_attach_exclusion(
1498                 lttng_event_enabler_as_enabler(event_enabler), excluder);
1499
1500         lttng_session_lazy_sync_event_enablers(event_enabler->chan->session);
1501         return 0;
1502 }
1503
1504 int lttng_event_notifier_enabler_enable(
1505                 struct lttng_event_notifier_enabler *event_notifier_enabler)
1506 {
1507         lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->enabled = 1;
1508         lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
1509
1510         return 0;
1511 }
1512
1513 int lttng_event_notifier_enabler_disable(
1514                 struct lttng_event_notifier_enabler *event_notifier_enabler)
1515 {
1516         lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->enabled = 0;
1517         lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
1518
1519         return 0;
1520 }
1521
1522 int lttng_event_notifier_enabler_attach_filter_bytecode(
1523                 struct lttng_event_notifier_enabler *event_notifier_enabler,
1524                 struct lttng_ust_bytecode_node **bytecode)
1525 {
1526         _lttng_enabler_attach_filter_bytecode(
1527                 lttng_event_notifier_enabler_as_enabler(event_notifier_enabler),
1528                 bytecode);
1529
1530         lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
1531         return 0;
1532 }
1533
1534 int lttng_event_notifier_enabler_attach_capture_bytecode(
1535                 struct lttng_event_notifier_enabler *event_notifier_enabler,
1536                 struct lttng_ust_bytecode_node **bytecode)
1537 {
1538         (*bytecode)->enabler = lttng_event_notifier_enabler_as_enabler(
1539                         event_notifier_enabler);
1540         cds_list_add_tail(&(*bytecode)->node,
1541                         &event_notifier_enabler->capture_bytecode_head);
1542         /* Take ownership of bytecode */
1543         *bytecode = NULL;
1544         event_notifier_enabler->num_captures++;
1545
1546         lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
1547         return 0;
1548 }
1549
1550 int lttng_event_notifier_enabler_attach_exclusion(
1551                 struct lttng_event_notifier_enabler *event_notifier_enabler,
1552                 struct lttng_ust_excluder_node **excluder)
1553 {
1554         _lttng_enabler_attach_exclusion(
1555                 lttng_event_notifier_enabler_as_enabler(event_notifier_enabler),
1556                 excluder);
1557
1558         lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
1559         return 0;
1560 }
1561
1562 int lttng_attach_context(struct lttng_ust_context *context_param,
1563                 union ust_args *uargs,
1564                 struct lttng_ctx **ctx, struct lttng_session *session)
1565 {
1566         /*
1567          * We cannot attach a context after trace has been started for a
1568          * session because the metadata does not allow expressing this
1569          * information outside of the original channel scope.
1570          */
1571         if (session->priv->been_active)
1572                 return -EPERM;
1573
1574         switch (context_param->ctx) {
1575         case LTTNG_UST_CONTEXT_PTHREAD_ID:
1576                 return lttng_add_pthread_id_to_ctx(ctx);
1577         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
1578         {
1579                 struct lttng_ust_perf_counter_ctx *perf_ctx_param;
1580
1581                 perf_ctx_param = &context_param->u.perf_counter;
1582                 return lttng_add_perf_counter_to_ctx(
1583                         perf_ctx_param->type,
1584                         perf_ctx_param->config,
1585                         perf_ctx_param->name,
1586                         ctx);
1587         }
1588         case LTTNG_UST_CONTEXT_VTID:
1589                 return lttng_add_vtid_to_ctx(ctx);
1590         case LTTNG_UST_CONTEXT_VPID:
1591                 return lttng_add_vpid_to_ctx(ctx);
1592         case LTTNG_UST_CONTEXT_PROCNAME:
1593                 return lttng_add_procname_to_ctx(ctx);
1594         case LTTNG_UST_CONTEXT_IP:
1595                 return lttng_add_ip_to_ctx(ctx);
1596         case LTTNG_UST_CONTEXT_CPU_ID:
1597                 return lttng_add_cpu_id_to_ctx(ctx);
1598         case LTTNG_UST_CONTEXT_APP_CONTEXT:
1599                 return lttng_ust_add_app_context_to_ctx_rcu(uargs->app_context.ctxname,
1600                         ctx);
1601         case LTTNG_UST_CONTEXT_CGROUP_NS:
1602                 return lttng_add_cgroup_ns_to_ctx(ctx);
1603         case LTTNG_UST_CONTEXT_IPC_NS:
1604                 return lttng_add_ipc_ns_to_ctx(ctx);
1605         case LTTNG_UST_CONTEXT_MNT_NS:
1606                 return lttng_add_mnt_ns_to_ctx(ctx);
1607         case LTTNG_UST_CONTEXT_NET_NS:
1608                 return lttng_add_net_ns_to_ctx(ctx);
1609         case LTTNG_UST_CONTEXT_PID_NS:
1610                 return lttng_add_pid_ns_to_ctx(ctx);
1611         case LTTNG_UST_CONTEXT_TIME_NS:
1612                 return lttng_add_time_ns_to_ctx(ctx);
1613         case LTTNG_UST_CONTEXT_USER_NS:
1614                 return lttng_add_user_ns_to_ctx(ctx);
1615         case LTTNG_UST_CONTEXT_UTS_NS:
1616                 return lttng_add_uts_ns_to_ctx(ctx);
1617         case LTTNG_UST_CONTEXT_VUID:
1618                 return lttng_add_vuid_to_ctx(ctx);
1619         case LTTNG_UST_CONTEXT_VEUID:
1620                 return lttng_add_veuid_to_ctx(ctx);
1621         case LTTNG_UST_CONTEXT_VSUID:
1622                 return lttng_add_vsuid_to_ctx(ctx);
1623         case LTTNG_UST_CONTEXT_VGID:
1624                 return lttng_add_vgid_to_ctx(ctx);
1625         case LTTNG_UST_CONTEXT_VEGID:
1626                 return lttng_add_vegid_to_ctx(ctx);
1627         case LTTNG_UST_CONTEXT_VSGID:
1628                 return lttng_add_vsgid_to_ctx(ctx);
1629         default:
1630                 return -EINVAL;
1631         }
1632 }
1633
1634 int lttng_event_enabler_attach_context(struct lttng_event_enabler *enabler,
1635                 struct lttng_ust_context *context_param)
1636 {
1637         return -ENOSYS;
1638 }
1639
1640 void lttng_event_enabler_destroy(struct lttng_event_enabler *event_enabler)
1641 {
1642         if (!event_enabler) {
1643                 return;
1644         }
1645         cds_list_del(&event_enabler->node);
1646
1647         lttng_enabler_destroy(lttng_event_enabler_as_enabler(event_enabler));
1648
1649         lttng_destroy_context(event_enabler->ctx);
1650         free(event_enabler);
1651 }
1652
1653 /*
1654  * lttng_session_sync_event_enablers should be called just before starting a
1655  * session.
1656  */
1657 static
1658 void lttng_session_sync_event_enablers(struct lttng_session *session)
1659 {
1660         struct lttng_event_enabler *event_enabler;
1661         struct lttng_ust_event_private *event_priv;
1662
1663         cds_list_for_each_entry(event_enabler, &session->priv->enablers_head, node)
1664                 lttng_event_enabler_ref_events(event_enabler);
1665         /*
1666          * For each event, if at least one of its enablers is enabled,
1667          * and its channel and session transient states are enabled, we
1668          * enable the event, else we disable it.
1669          */
1670         cds_list_for_each_entry(event_priv, &session->priv->events_head, node) {
1671                 struct lttng_enabler_ref *enabler_ref;
1672                 struct lttng_bytecode_runtime *runtime;
1673                 int enabled = 0, has_enablers_without_bytecode = 0;
1674
1675                 /* Enable events */
1676                 cds_list_for_each_entry(enabler_ref,
1677                                 &event_priv->enablers_ref_head, node) {
1678                         if (enabler_ref->ref->enabled) {
1679                                 enabled = 1;
1680                                 break;
1681                         }
1682                 }
1683                 /*
1684                  * Enabled state is based on union of enablers, with
1685                  * intesection of session and channel transient enable
1686                  * states.
1687                  */
1688                 enabled = enabled && session->priv->tstate && event_priv->pub->chan->tstate;
1689
1690                 CMM_STORE_SHARED(event_priv->pub->enabled, enabled);
1691                 /*
1692                  * Sync tracepoint registration with event enabled
1693                  * state.
1694                  */
1695                 if (enabled) {
1696                         if (!event_priv->registered)
1697                                 register_event(event_priv->pub);
1698                 } else {
1699                         if (event_priv->registered)
1700                                 unregister_event(event_priv->pub);
1701                 }
1702
1703                 /* Check if has enablers without bytecode enabled */
1704                 cds_list_for_each_entry(enabler_ref,
1705                                 &event_priv->enablers_ref_head, node) {
1706                         if (enabler_ref->ref->enabled
1707                                         && cds_list_empty(&enabler_ref->ref->filter_bytecode_head)) {
1708                                 has_enablers_without_bytecode = 1;
1709                                 break;
1710                         }
1711                 }
1712                 event_priv->pub->has_enablers_without_bytecode =
1713                         has_enablers_without_bytecode;
1714
1715                 /* Enable filters */
1716                 cds_list_for_each_entry(runtime,
1717                                 &event_priv->pub->filter_bytecode_runtime_head, node) {
1718                         lttng_bytecode_filter_sync_state(runtime);
1719                 }
1720         }
1721         __tracepoint_probe_prune_release_queue();
1722 }
1723
1724 /* Support for event notifier is introduced by probe provider major version 2. */
1725 static
1726 bool lttng_ust_probe_supports_event_notifier(struct lttng_probe_desc *probe_desc)
1727 {
1728         return probe_desc->major >= 2;
1729 }
1730
1731 static
1732 void lttng_create_event_notifier_if_missing(
1733                 struct lttng_event_notifier_enabler *event_notifier_enabler)
1734 {
1735         struct lttng_event_notifier_group *event_notifier_group = event_notifier_enabler->group;
1736         struct lttng_probe_desc *probe_desc;
1737         struct cds_list_head *probe_list;
1738         int i;
1739
1740         probe_list = lttng_get_probe_list_head();
1741
1742         cds_list_for_each_entry(probe_desc, probe_list, head) {
1743                 for (i = 0; i < probe_desc->nr_events; i++) {
1744                         int ret;
1745                         bool found = false;
1746                         const struct lttng_event_desc *desc;
1747                         struct lttng_event_notifier *event_notifier;
1748                         struct cds_hlist_head *head;
1749                         struct cds_hlist_node *node;
1750
1751                         desc = probe_desc->event_desc[i];
1752
1753                         if (!lttng_desc_match_enabler(desc,
1754                                         lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)))
1755                                 continue;
1756
1757                         /*
1758                          * Given the current event_notifier group, get the bucket that
1759                          * the target event_notifier would be if it was already
1760                          * created.
1761                          */
1762                         head = borrow_hash_table_bucket(
1763                                 event_notifier_group->event_notifiers_ht.table,
1764                                 LTTNG_UST_EVENT_NOTIFIER_HT_SIZE, desc);
1765
1766                         cds_hlist_for_each_entry(event_notifier, node, head, hlist) {
1767                                 /*
1768                                  * Check if event_notifier already exists by checking
1769                                  * if the event_notifier and enabler share the same
1770                                  * description and id.
1771                                  */
1772                                 if (event_notifier->desc == desc &&
1773                                                 event_notifier->user_token == event_notifier_enabler->user_token) {
1774                                         found = true;
1775                                         break;
1776                                 }
1777                         }
1778
1779                         if (found)
1780                                 continue;
1781
1782                         /* Check that the probe supports event notifiers, else report the error. */
1783                         if (!lttng_ust_probe_supports_event_notifier(probe_desc)) {
1784                                 ERR("Probe \"%s\" contains event \"%s\" which matches an enabled event notifier, "
1785                                         "but its version (%u.%u) is too old and does not implement event notifiers. "
1786                                         "It needs to be recompiled against a newer version of LTTng-UST, otherwise "
1787                                         "this event will not generate any notification.",
1788                                         probe_desc->provider,
1789                                         desc->name,
1790                                         probe_desc->major,
1791                                         probe_desc->minor);
1792                                 continue;
1793                         }
1794                         /*
1795                          * We need to create a event_notifier for this event probe.
1796                          */
1797                         ret = lttng_event_notifier_create(desc,
1798                                 event_notifier_enabler->user_token,
1799                                 event_notifier_enabler->error_counter_index,
1800                                 event_notifier_group);
1801                         if (ret) {
1802                                 DBG("Unable to create event_notifier %s, error %d\n",
1803                                         probe_desc->event_desc[i]->name, ret);
1804                         }
1805                 }
1806         }
1807 }
1808
1809 /*
1810  * Create event_notifiers associated with a event_notifier enabler (if not already present).
1811  */
1812 static
1813 int lttng_event_notifier_enabler_ref_event_notifiers(
1814                 struct lttng_event_notifier_enabler *event_notifier_enabler)
1815 {
1816         struct lttng_event_notifier_group *event_notifier_group = event_notifier_enabler->group;
1817         struct lttng_event_notifier *event_notifier;
1818
1819          /*
1820           * Only try to create event_notifiers for enablers that are enabled, the user
1821           * might still be attaching filter or exclusion to the
1822           * event_notifier_enabler.
1823           */
1824         if (!lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->enabled)
1825                 goto end;
1826
1827         /* First, ensure that probe event_notifiers are created for this enabler. */
1828         lttng_create_event_notifier_if_missing(event_notifier_enabler);
1829
1830         /* Link the created event_notifier with its associated enabler. */
1831         cds_list_for_each_entry(event_notifier, &event_notifier_group->event_notifiers_head, node) {
1832                 struct lttng_enabler_ref *enabler_ref;
1833
1834                 if (!lttng_event_notifier_enabler_match_event_notifier(event_notifier_enabler, event_notifier))
1835                         continue;
1836
1837                 enabler_ref = lttng_enabler_ref(&event_notifier->enablers_ref_head,
1838                         lttng_event_notifier_enabler_as_enabler(event_notifier_enabler));
1839                 if (!enabler_ref) {
1840                         /*
1841                          * If no backward ref, create it.
1842                          * Add backward ref from event_notifier to enabler.
1843                          */
1844                         enabler_ref = zmalloc(sizeof(*enabler_ref));
1845                         if (!enabler_ref)
1846                                 return -ENOMEM;
1847
1848                         enabler_ref->ref = lttng_event_notifier_enabler_as_enabler(
1849                                 event_notifier_enabler);
1850                         cds_list_add(&enabler_ref->node,
1851                                 &event_notifier->enablers_ref_head);
1852                 }
1853
1854                 /*
1855                  * Link filter bytecodes if not linked yet.
1856                  */
1857                 lttng_enabler_link_bytecode(event_notifier->desc,
1858                         &event_notifier_group->ctx,
1859                         &event_notifier->filter_bytecode_runtime_head,
1860                         &lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->filter_bytecode_head);
1861
1862                 /*
1863                  * Link capture bytecodes if not linked yet.
1864                  */
1865                 lttng_enabler_link_bytecode(event_notifier->desc,
1866                         &event_notifier_group->ctx, &event_notifier->capture_bytecode_runtime_head,
1867                         &event_notifier_enabler->capture_bytecode_head);
1868
1869                 event_notifier->num_captures = event_notifier_enabler->num_captures;
1870         }
1871 end:
1872         return 0;
1873 }
1874
1875 static
1876 void lttng_event_notifier_group_sync_enablers(struct lttng_event_notifier_group *event_notifier_group)
1877 {
1878         struct lttng_event_notifier_enabler *event_notifier_enabler;
1879         struct lttng_event_notifier *event_notifier;
1880
1881         cds_list_for_each_entry(event_notifier_enabler, &event_notifier_group->enablers_head, node)
1882                 lttng_event_notifier_enabler_ref_event_notifiers(event_notifier_enabler);
1883
1884         /*
1885          * For each event_notifier, if at least one of its enablers is enabled,
1886          * we enable the event_notifier, else we disable it.
1887          */
1888         cds_list_for_each_entry(event_notifier, &event_notifier_group->event_notifiers_head, node) {
1889                 struct lttng_enabler_ref *enabler_ref;
1890                 struct lttng_bytecode_runtime *runtime;
1891                 int enabled = 0, has_enablers_without_bytecode = 0;
1892
1893                 /* Enable event_notifiers */
1894                 cds_list_for_each_entry(enabler_ref,
1895                                 &event_notifier->enablers_ref_head, node) {
1896                         if (enabler_ref->ref->enabled) {
1897                                 enabled = 1;
1898                                 break;
1899                         }
1900                 }
1901
1902                 CMM_STORE_SHARED(event_notifier->enabled, enabled);
1903                 /*
1904                  * Sync tracepoint registration with event_notifier enabled
1905                  * state.
1906                  */
1907                 if (enabled) {
1908                         if (!event_notifier->registered)
1909                                 register_event_notifier(event_notifier);
1910                 } else {
1911                         if (event_notifier->registered)
1912                                 unregister_event_notifier(event_notifier);
1913                 }
1914
1915                 /* Check if has enablers without bytecode enabled */
1916                 cds_list_for_each_entry(enabler_ref,
1917                                 &event_notifier->enablers_ref_head, node) {
1918                         if (enabler_ref->ref->enabled
1919                                         && cds_list_empty(&enabler_ref->ref->filter_bytecode_head)) {
1920                                 has_enablers_without_bytecode = 1;
1921                                 break;
1922                         }
1923                 }
1924                 event_notifier->has_enablers_without_bytecode =
1925                         has_enablers_without_bytecode;
1926
1927                 /* Enable filters */
1928                 cds_list_for_each_entry(runtime,
1929                                 &event_notifier->filter_bytecode_runtime_head, node) {
1930                         lttng_bytecode_filter_sync_state(runtime);
1931                 }
1932
1933                 /* Enable captures. */
1934                 cds_list_for_each_entry(runtime,
1935                                 &event_notifier->capture_bytecode_runtime_head, node) {
1936                         lttng_bytecode_capture_sync_state(runtime);
1937                 }
1938         }
1939         __tracepoint_probe_prune_release_queue();
1940 }
1941
1942 /*
1943  * Apply enablers to session events, adding events to session if need
1944  * be. It is required after each modification applied to an active
1945  * session, and right before session "start".
1946  * "lazy" sync means we only sync if required.
1947  */
1948 static
1949 void lttng_session_lazy_sync_event_enablers(struct lttng_session *session)
1950 {
1951         /* We can skip if session is not active */
1952         if (!session->active)
1953                 return;
1954         lttng_session_sync_event_enablers(session);
1955 }
1956
1957 /*
1958  * Update all sessions with the given app context.
1959  * Called with ust lock held.
1960  * This is invoked when an application context gets loaded/unloaded. It
1961  * ensures the context callbacks are in sync with the application
1962  * context (either app context callbacks, or dummy callbacks).
1963  */
1964 void lttng_ust_context_set_session_provider(const char *name,
1965                 size_t (*get_size)(struct lttng_ctx_field *field, size_t offset),
1966                 void (*record)(struct lttng_ctx_field *field,
1967                         struct lttng_ust_lib_ring_buffer_ctx *ctx,
1968                         struct lttng_channel *chan),
1969                 void (*get_value)(struct lttng_ctx_field *field,
1970                         struct lttng_ctx_value *value))
1971 {
1972         struct lttng_ust_session_private *session_priv;
1973
1974         cds_list_for_each_entry(session_priv, &sessions, node) {
1975                 struct lttng_channel *chan;
1976                 struct lttng_ust_event_private *event_priv;
1977                 int ret;
1978
1979                 ret = lttng_ust_context_set_provider_rcu(&session_priv->ctx,
1980                                 name, get_size, record, get_value);
1981                 if (ret)
1982                         abort();
1983                 cds_list_for_each_entry(chan, &session_priv->chan_head, node) {
1984                         ret = lttng_ust_context_set_provider_rcu(&chan->ctx,
1985                                         name, get_size, record, get_value);
1986                         if (ret)
1987                                 abort();
1988                 }
1989                 cds_list_for_each_entry(event_priv, &session_priv->events_head, node) {
1990                         ret = lttng_ust_context_set_provider_rcu(&event_priv->pub->ctx,
1991                                         name, get_size, record, get_value);
1992                         if (ret)
1993                                 abort();
1994                 }
1995         }
1996 }
1997
1998 /*
1999  * Update all event_notifier groups with the given app context.
2000  * Called with ust lock held.
2001  * This is invoked when an application context gets loaded/unloaded. It
2002  * ensures the context callbacks are in sync with the application
2003  * context (either app context callbacks, or dummy callbacks).
2004  */
2005 void lttng_ust_context_set_event_notifier_group_provider(const char *name,
2006                 size_t (*get_size)(struct lttng_ctx_field *field, size_t offset),
2007                 void (*record)(struct lttng_ctx_field *field,
2008                         struct lttng_ust_lib_ring_buffer_ctx *ctx,
2009                         struct lttng_channel *chan),
2010                 void (*get_value)(struct lttng_ctx_field *field,
2011                         struct lttng_ctx_value *value))
2012 {
2013         struct lttng_event_notifier_group *event_notifier_group;
2014
2015         cds_list_for_each_entry(event_notifier_group, &event_notifier_groups, node) {
2016                 int ret;
2017
2018                 ret = lttng_ust_context_set_provider_rcu(
2019                                 &event_notifier_group->ctx,
2020                                 name, get_size, record, get_value);
2021                 if (ret)
2022                         abort();
2023         }
2024 }