src/lib/lttng-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 "common/logging.h"
  36 #include "common/macros.h"
  37 #include <lttng/ust-ctl.h>
  38 #include "common/ustcomm.h"
  39 #include "common/ust-fd.h"
  40 #include "common/dynamic-type.h"
  41 #include "common/ust-context-provider.h"
  42 #include "error.h"
  43 #include "lttng-ust-uuid.h"
  44
  45 #include "tracepoint-internal.h"
  46 #include "string-utils.h"
  47 #include "lttng-bytecode.h"
  48 #include "lttng-tracer.h"
  49 #include "lttng-tracer-core.h"
  50 #include "lttng-ust-statedump.h"
  51 #include "context-internal.h"
  52 #include "lib/lttng-ust/events.h"
  53 #include "wait.h"
  54 #include "common/ringbuffer/shm.h"
  55 #include "common/ringbuffer/frontend_types.h"
  56 #include "common/ringbuffer/frontend.h"
  57 #include "common/counter/counter.h"
  58 #include "common/jhash.h"
  59 #include <lttng/ust-abi.h>
  60 #include "context-provider-internal.h"
  61
  62 /*
  63  * All operations within this file are called by the communication
  64  * thread, under ust_lock protection.
  65  */
  66
  67 static CDS_LIST_HEAD(sessions);
  68 static CDS_LIST_HEAD(event_notifier_groups);
  69
  70 struct cds_list_head *lttng_get_sessions(void)
  71 {
  72         return &sessions;
  73 }
  74
  75 static void _lttng_event_destroy(struct lttng_ust_event_common *event);
  76 static void _lttng_enum_destroy(struct lttng_enum *_enum);
  77
  78 static
  79 void lttng_session_lazy_sync_event_enablers(struct lttng_ust_session *session);
  80 static
  81 void lttng_session_sync_event_enablers(struct lttng_ust_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 bool lttng_ust_validate_event_name(const struct lttng_ust_event_desc *desc)
  89 {
  90         if (strlen(desc->probe_desc->provider_name) + 1 +
  91                         strlen(desc->event_name) >= LTTNG_UST_ABI_SYM_NAME_LEN)
  92                 return false;
  93         return true;
  94 }
  95
  96 void lttng_ust_format_event_name(const struct lttng_ust_event_desc *desc,
  97                 char *name)
  98 {
  99         strcpy(name, desc->probe_desc->provider_name);
 100         strcat(name, ":");
 101         strcat(name, desc->event_name);
 102 }
 103
 104 /*
 105  * Called with ust lock held.
 106  */
 107 int lttng_session_active(void)
 108 {
 109         struct lttng_ust_session_private *iter;
 110
 111         cds_list_for_each_entry(iter, &sessions, node) {
 112                 if (iter->pub->active)
 113                         return 1;
 114         }
 115         return 0;
 116 }
 117
 118 static
 119 int lttng_loglevel_match(int loglevel,
 120                 unsigned int has_loglevel,
 121                 enum lttng_ust_abi_loglevel_type req_type,
 122                 int req_loglevel)
 123 {
 124         if (!has_loglevel)
 125                 loglevel = TRACE_DEFAULT;
 126         switch (req_type) {
 127         case LTTNG_UST_ABI_LOGLEVEL_RANGE:
 128                 if (loglevel <= req_loglevel
 129                                 || (req_loglevel == -1 && loglevel <= TRACE_DEBUG))
 130                         return 1;
 131                 else
 132                         return 0;
 133         case LTTNG_UST_ABI_LOGLEVEL_SINGLE:
 134                 if (loglevel == req_loglevel
 135                                 || (req_loglevel == -1 && loglevel <= TRACE_DEBUG))
 136                         return 1;
 137                 else
 138                         return 0;
 139         case LTTNG_UST_ABI_LOGLEVEL_ALL:
 140         default:
 141                 if (loglevel <= TRACE_DEBUG)
 142                         return 1;
 143                 else
 144                         return 0;
 145         }
 146 }
 147
 148 struct lttng_ust_session *lttng_session_create(void)
 149 {
 150         struct lttng_ust_session *session;
 151         struct lttng_ust_session_private *session_priv;
 152         int i;
 153
 154         session = zmalloc(sizeof(struct lttng_ust_session));
 155         if (!session)
 156                 return NULL;
 157         session->struct_size = sizeof(struct lttng_ust_session);
 158         session_priv = zmalloc(sizeof(struct lttng_ust_session_private));
 159         if (!session_priv) {
 160                 free(session);
 161                 return NULL;
 162         }
 163         session->priv = session_priv;
 164         session_priv->pub = session;
 165         if (lttng_context_init_all(&session->priv->ctx)) {
 166                 free(session_priv);
 167                 free(session);
 168                 return NULL;
 169         }
 170         CDS_INIT_LIST_HEAD(&session->priv->chan_head);
 171         CDS_INIT_LIST_HEAD(&session->priv->events_head);
 172         CDS_INIT_LIST_HEAD(&session->priv->enums_head);
 173         CDS_INIT_LIST_HEAD(&session->priv->enablers_head);
 174         for (i = 0; i < LTTNG_UST_EVENT_HT_SIZE; i++)
 175                 CDS_INIT_HLIST_HEAD(&session->priv->events_ht.table[i]);
 176         for (i = 0; i < LTTNG_UST_ENUM_HT_SIZE; i++)
 177                 CDS_INIT_HLIST_HEAD(&session->priv->enums_ht.table[i]);
 178         cds_list_add(&session->priv->node, &sessions);
 179         return session;
 180 }
 181
 182 struct lttng_counter *lttng_ust_counter_create(
 183                 const char *counter_transport_name,
 184                 size_t number_dimensions, const struct lttng_counter_dimension *dimensions)
 185 {
 186         struct lttng_counter_transport *counter_transport = NULL;
 187         struct lttng_counter *counter = NULL;
 188
 189         counter_transport = lttng_counter_transport_find(counter_transport_name);
 190         if (!counter_transport)
 191                 goto notransport;
 192         counter = zmalloc(sizeof(struct lttng_counter));
 193         if (!counter)
 194                 goto nomem;
 195
 196         counter->ops = &counter_transport->ops;
 197         counter->transport = counter_transport;
 198
 199         counter->counter = counter->ops->counter_create(
 200                         number_dimensions, dimensions, 0,
 201                         -1, 0, NULL, false);
 202         if (!counter->counter) {
 203                 goto create_error;
 204         }
 205
 206         return counter;
 207
 208 create_error:
 209         free(counter);
 210 nomem:
 211 notransport:
 212         return NULL;
 213 }
 214
 215 static
 216 void lttng_ust_counter_destroy(struct lttng_counter *counter)
 217 {
 218         counter->ops->counter_destroy(counter->counter);
 219         free(counter);
 220 }
 221
 222 struct lttng_event_notifier_group *lttng_event_notifier_group_create(void)
 223 {
 224         struct lttng_event_notifier_group *event_notifier_group;
 225         int i;
 226
 227         event_notifier_group = zmalloc(sizeof(struct lttng_event_notifier_group));
 228         if (!event_notifier_group)
 229                 return NULL;
 230
 231         /* Add all contexts. */
 232         if (lttng_context_init_all(&event_notifier_group->ctx)) {
 233                 free(event_notifier_group);
 234                 return NULL;
 235         }
 236
 237         CDS_INIT_LIST_HEAD(&event_notifier_group->enablers_head);
 238         CDS_INIT_LIST_HEAD(&event_notifier_group->event_notifiers_head);
 239         for (i = 0; i < LTTNG_UST_EVENT_NOTIFIER_HT_SIZE; i++)
 240                 CDS_INIT_HLIST_HEAD(&event_notifier_group->event_notifiers_ht.table[i]);
 241
 242         cds_list_add(&event_notifier_group->node, &event_notifier_groups);
 243
 244         return event_notifier_group;
 245 }
 246
 247 /*
 248  * Only used internally at session destruction.
 249  */
 250 static
 251 void _lttng_channel_unmap(struct lttng_ust_channel_buffer *lttng_chan)
 252 {
 253         struct lttng_ust_lib_ring_buffer_channel *chan;
 254         struct lttng_ust_shm_handle *handle;
 255
 256         cds_list_del(&lttng_chan->priv->node);
 257         lttng_destroy_context(lttng_chan->priv->ctx);
 258         chan = lttng_chan->priv->rb_chan;
 259         handle = chan->handle;
 260         channel_destroy(chan, handle, 0);
 261         free(lttng_chan->parent);
 262         free(lttng_chan->priv);
 263         free(lttng_chan);
 264 }
 265
 266 static
 267 void register_event(struct lttng_ust_event_common *event)
 268 {
 269         int ret;
 270         const struct lttng_ust_event_desc *desc;
 271         char name[LTTNG_UST_ABI_SYM_NAME_LEN];
 272
 273         assert(event->priv->registered == 0);
 274         desc = event->priv->desc;
 275         lttng_ust_format_event_name(desc, name);
 276         ret = lttng_ust_tp_probe_register_queue_release(name,
 277                         desc->probe_callback,
 278                         event, desc->signature);
 279         WARN_ON_ONCE(ret);
 280         if (!ret)
 281                 event->priv->registered = 1;
 282 }
 283
 284 static
 285 void unregister_event(struct lttng_ust_event_common *event)
 286 {
 287         int ret;
 288         const struct lttng_ust_event_desc *desc;
 289         char name[LTTNG_UST_ABI_SYM_NAME_LEN];
 290
 291         assert(event->priv->registered == 1);
 292         desc = event->priv->desc;
 293         lttng_ust_format_event_name(desc, name);
 294         ret = lttng_ust_tp_probe_unregister_queue_release(name,
 295                         desc->probe_callback,
 296                         event);
 297         WARN_ON_ONCE(ret);
 298         if (!ret)
 299                 event->priv->registered = 0;
 300 }
 301
 302 static
 303 void _lttng_event_unregister(struct lttng_ust_event_common *event)
 304 {
 305         if (event->priv->registered)
 306                 unregister_event(event);
 307 }
 308
 309 void lttng_session_destroy(struct lttng_ust_session *session)
 310 {
 311         struct lttng_ust_channel_buffer_private *chan, *tmpchan;
 312         struct lttng_ust_event_recorder_private *event_recorder_priv, *tmpevent_recorder_priv;
 313         struct lttng_enum *_enum, *tmp_enum;
 314         struct lttng_event_enabler *event_enabler, *event_tmpenabler;
 315
 316         CMM_ACCESS_ONCE(session->active) = 0;
 317         cds_list_for_each_entry(event_recorder_priv, &session->priv->events_head, node) {
 318                 _lttng_event_unregister(event_recorder_priv->parent.pub);
 319         }
 320         lttng_ust_urcu_synchronize_rcu();       /* Wait for in-flight events to complete */
 321         lttng_ust_tp_probe_prune_release_queue();
 322         cds_list_for_each_entry_safe(event_enabler, event_tmpenabler,
 323                         &session->priv->enablers_head, node)
 324                 lttng_event_enabler_destroy(event_enabler);
 325         cds_list_for_each_entry_safe(event_recorder_priv, tmpevent_recorder_priv,
 326                         &session->priv->events_head, node)
 327                 _lttng_event_destroy(event_recorder_priv->parent.pub);
 328         cds_list_for_each_entry_safe(_enum, tmp_enum,
 329                         &session->priv->enums_head, node)
 330                 _lttng_enum_destroy(_enum);
 331         cds_list_for_each_entry_safe(chan, tmpchan, &session->priv->chan_head, node)
 332                 _lttng_channel_unmap(chan->pub);
 333         cds_list_del(&session->priv->node);
 334         lttng_destroy_context(session->priv->ctx);
 335         free(session->priv);
 336         free(session);
 337 }
 338
 339 void lttng_event_notifier_group_destroy(
 340                 struct lttng_event_notifier_group *event_notifier_group)
 341 {
 342         int close_ret;
 343         struct lttng_event_notifier_enabler *notifier_enabler, *tmpnotifier_enabler;
 344         struct lttng_ust_event_notifier_private *event_notifier_priv, *tmpevent_notifier_priv;
 345
 346         if (!event_notifier_group) {
 347                 return;
 348         }
 349
 350         cds_list_for_each_entry(event_notifier_priv,
 351                         &event_notifier_group->event_notifiers_head, node)
 352                 _lttng_event_unregister(event_notifier_priv->parent.pub);
 353
 354         lttng_ust_urcu_synchronize_rcu();
 355
 356         cds_list_for_each_entry_safe(notifier_enabler, tmpnotifier_enabler,
 357                         &event_notifier_group->enablers_head, node)
 358                 lttng_event_notifier_enabler_destroy(notifier_enabler);
 359
 360         cds_list_for_each_entry_safe(event_notifier_priv, tmpevent_notifier_priv,
 361                         &event_notifier_group->event_notifiers_head, node)
 362                 _lttng_event_destroy(event_notifier_priv->parent.pub);
 363
 364         if (event_notifier_group->error_counter)
 365                 lttng_ust_counter_destroy(event_notifier_group->error_counter);
 366
 367         /* Close the notification fd to the listener of event_notifiers. */
 368
 369         lttng_ust_lock_fd_tracker();
 370         close_ret = close(event_notifier_group->notification_fd);
 371         if (!close_ret) {
 372                 lttng_ust_delete_fd_from_tracker(
 373                                 event_notifier_group->notification_fd);
 374         } else {
 375                 PERROR("close");
 376                 abort();
 377         }
 378         lttng_ust_unlock_fd_tracker();
 379
 380         cds_list_del(&event_notifier_group->node);
 381         lttng_destroy_context(event_notifier_group->ctx);
 382         free(event_notifier_group);
 383 }
 384
 385 static
 386 void lttng_enabler_destroy(struct lttng_enabler *enabler)
 387 {
 388         struct lttng_ust_bytecode_node *filter_node, *tmp_filter_node;
 389         struct lttng_ust_excluder_node *excluder_node, *tmp_excluder_node;
 390
 391         if (!enabler) {
 392                 return;
 393         }
 394
 395         /* Destroy filter bytecode */
 396         cds_list_for_each_entry_safe(filter_node, tmp_filter_node,
 397                         &enabler->filter_bytecode_head, node) {
 398                 free(filter_node);
 399         }
 400
 401         /* Destroy excluders */
 402         cds_list_for_each_entry_safe(excluder_node, tmp_excluder_node,
 403                         &enabler->excluder_head, node) {
 404                 free(excluder_node);
 405         }
 406 }
 407
 408  void lttng_event_notifier_enabler_destroy(struct lttng_event_notifier_enabler *event_notifier_enabler)
 409 {
 410         if (!event_notifier_enabler) {
 411                 return;
 412         }
 413
 414         cds_list_del(&event_notifier_enabler->node);
 415
 416         lttng_enabler_destroy(lttng_event_notifier_enabler_as_enabler(event_notifier_enabler));
 417
 418         free(event_notifier_enabler);
 419 }
 420
 421 static
 422 int lttng_enum_create(const struct lttng_ust_enum_desc *desc,
 423                 struct lttng_ust_session *session)
 424 {
 425         const char *enum_name = desc->name;
 426         struct lttng_enum *_enum;
 427         struct cds_hlist_head *head;
 428         int ret = 0;
 429         size_t name_len = strlen(enum_name);
 430         uint32_t hash;
 431         int notify_socket;
 432
 433         /* Check if this enum is already registered for this session. */
 434         hash = jhash(enum_name, name_len, 0);
 435         head = &session->priv->enums_ht.table[hash & (LTTNG_UST_ENUM_HT_SIZE - 1)];
 436
 437         _enum = lttng_ust_enum_get_from_desc(session, desc);
 438         if (_enum) {
 439                 ret = -EEXIST;
 440                 goto exist;
 441         }
 442
 443         notify_socket = lttng_get_notify_socket(session->priv->owner);
 444         if (notify_socket < 0) {
 445                 ret = notify_socket;
 446                 goto socket_error;
 447         }
 448
 449         _enum = zmalloc(sizeof(*_enum));
 450         if (!_enum) {
 451                 ret = -ENOMEM;
 452                 goto cache_error;
 453         }
 454         _enum->session = session;
 455         _enum->desc = desc;
 456
 457         ret = ustcomm_register_enum(notify_socket,
 458                 session->priv->objd,
 459                 enum_name,
 460                 desc->nr_entries,
 461                 desc->entries,
 462                 &_enum->id);
 463         if (ret < 0) {
 464                 DBG("Error (%d) registering enumeration to sessiond", ret);
 465                 goto sessiond_register_error;
 466         }
 467         cds_list_add(&_enum->node, &session->priv->enums_head);
 468         cds_hlist_add_head(&_enum->hlist, head);
 469         return 0;
 470
 471 sessiond_register_error:
 472         free(_enum);
 473 cache_error:
 474 socket_error:
 475 exist:
 476         return ret;
 477 }
 478
 479 static
 480 int lttng_create_enum_check(const struct lttng_ust_type_common *type,
 481                 struct lttng_ust_session *session)
 482 {
 483         switch (type->type) {
 484         case lttng_ust_type_enum:
 485         {
 486                 const struct lttng_ust_enum_desc *enum_desc;
 487                 int ret;
 488
 489                 enum_desc = lttng_ust_get_type_enum(type)->desc;
 490                 ret = lttng_enum_create(enum_desc, session);
 491                 if (ret && ret != -EEXIST) {
 492                         DBG("Unable to create enum error: (%d)", ret);
 493                         return ret;
 494                 }
 495                 break;
 496         }
 497         case lttng_ust_type_dynamic:
 498         {
 499                 const struct lttng_ust_event_field *tag_field_generic;
 500                 const struct lttng_ust_enum_desc *enum_desc;
 501                 int ret;
 502
 503                 tag_field_generic = lttng_ust_dynamic_type_tag_field();
 504                 enum_desc = lttng_ust_get_type_enum(tag_field_generic->type)->desc;
 505                 ret = lttng_enum_create(enum_desc, session);
 506                 if (ret && ret != -EEXIST) {
 507                         DBG("Unable to create enum error: (%d)", ret);
 508                         return ret;
 509                 }
 510                 break;
 511         }
 512         default:
 513                 /* TODO: nested types when they become supported. */
 514                 break;
 515         }
 516         return 0;
 517 }
 518
 519 static
 520 int lttng_create_all_event_enums(size_t nr_fields,
 521                 const struct lttng_ust_event_field **event_fields,
 522                 struct lttng_ust_session *session)
 523 {
 524         size_t i;
 525         int ret;
 526
 527         /* For each field, ensure enum is part of the session. */
 528         for (i = 0; i < nr_fields; i++) {
 529                 const struct lttng_ust_type_common *type = event_fields[i]->type;
 530
 531                 ret = lttng_create_enum_check(type, session);
 532                 if (ret)
 533                         return ret;
 534         }
 535         return 0;
 536 }
 537
 538 static
 539 int lttng_create_all_ctx_enums(size_t nr_fields,
 540                 struct lttng_ust_ctx_field *ctx_fields,
 541                 struct lttng_ust_session *session)
 542 {
 543         size_t i;
 544         int ret;
 545
 546         /* For each field, ensure enum is part of the session. */
 547         for (i = 0; i < nr_fields; i++) {
 548                 const struct lttng_ust_type_common *type = ctx_fields[i].event_field->type;
 549
 550                 ret = lttng_create_enum_check(type, session);
 551                 if (ret)
 552                         return ret;
 553         }
 554         return 0;
 555 }
 556
 557 /*
 558  * Ensure that a state-dump will be performed for this session at the end
 559  * of the current handle_message().
 560  */
 561 int lttng_session_statedump(struct lttng_ust_session *session)
 562 {
 563         session->priv->statedump_pending = 1;
 564         lttng_ust_sockinfo_session_enabled(session->priv->owner);
 565         return 0;
 566 }
 567
 568 int lttng_session_enable(struct lttng_ust_session *session)
 569 {
 570         int ret = 0;
 571         struct lttng_ust_channel_buffer_private *chan;
 572         int notify_socket;
 573
 574         if (session->active) {
 575                 ret = -EBUSY;
 576                 goto end;
 577         }
 578
 579         notify_socket = lttng_get_notify_socket(session->priv->owner);
 580         if (notify_socket < 0)
 581                 return notify_socket;
 582
 583         /* Set transient enabler state to "enabled" */
 584         session->priv->tstate = 1;
 585
 586         /* We need to sync enablers with session before activation. */
 587         lttng_session_sync_event_enablers(session);
 588
 589         /*
 590          * Snapshot the number of events per channel to know the type of header
 591          * we need to use.
 592          */
 593         cds_list_for_each_entry(chan, &session->priv->chan_head, node) {
 594                 struct lttng_ust_ctx *ctx;
 595                 struct lttng_ust_ctx_field *fields = NULL;
 596                 size_t nr_fields = 0;
 597                 uint32_t chan_id;
 598
 599                 /* don't change it if session stop/restart */
 600                 if (chan->header_type)
 601                         continue;
 602                 ctx = chan->ctx;
 603                 if (ctx) {
 604                         nr_fields = ctx->nr_fields;
 605                         fields = ctx->fields;
 606                         ret = lttng_create_all_ctx_enums(nr_fields, fields,
 607                                 session);
 608                         if (ret < 0) {
 609                                 DBG("Error (%d) adding enum to session", ret);
 610                                 return ret;
 611                         }
 612                 }
 613                 ret = ustcomm_register_channel(notify_socket,
 614                         session,
 615                         session->priv->objd,
 616                         chan->parent.objd,
 617                         nr_fields,
 618                         fields,
 619                         &chan_id,
 620                         &chan->header_type);
 621                 if (ret) {
 622                         DBG("Error (%d) registering channel to sessiond", ret);
 623                         return ret;
 624                 }
 625                 if (chan_id != chan->id) {
 626                         DBG("Error: channel registration id (%u) does not match id assigned at creation (%u)",
 627                                 chan_id, chan->id);
 628                         return -EINVAL;
 629                 }
 630         }
 631
 632         /* Set atomically the state to "active" */
 633         CMM_ACCESS_ONCE(session->active) = 1;
 634         CMM_ACCESS_ONCE(session->priv->been_active) = 1;
 635
 636         ret = lttng_session_statedump(session);
 637         if (ret)
 638                 return ret;
 639 end:
 640         return ret;
 641 }
 642
 643 int lttng_session_disable(struct lttng_ust_session *session)
 644 {
 645         int ret = 0;
 646
 647         if (!session->active) {
 648                 ret = -EBUSY;
 649                 goto end;
 650         }
 651         /* Set atomically the state to "inactive" */
 652         CMM_ACCESS_ONCE(session->active) = 0;
 653
 654         /* Set transient enabler state to "disabled" */
 655         session->priv->tstate = 0;
 656         lttng_session_sync_event_enablers(session);
 657 end:
 658         return ret;
 659 }
 660
 661 int lttng_channel_enable(struct lttng_ust_channel_common *lttng_channel)
 662 {
 663         int ret = 0;
 664
 665         if (lttng_channel->enabled) {
 666                 ret = -EBUSY;
 667                 goto end;
 668         }
 669         /* Set transient enabler state to "enabled" */
 670         lttng_channel->priv->tstate = 1;
 671         lttng_session_sync_event_enablers(lttng_channel->session);
 672         /* Set atomically the state to "enabled" */
 673         CMM_ACCESS_ONCE(lttng_channel->enabled) = 1;
 674 end:
 675         return ret;
 676 }
 677
 678 int lttng_channel_disable(struct lttng_ust_channel_common *lttng_channel)
 679 {
 680         int ret = 0;
 681
 682         if (!lttng_channel->enabled) {
 683                 ret = -EBUSY;
 684                 goto end;
 685         }
 686         /* Set atomically the state to "disabled" */
 687         CMM_ACCESS_ONCE(lttng_channel->enabled) = 0;
 688         /* Set transient enabler state to "enabled" */
 689         lttng_channel->priv->tstate = 0;
 690         lttng_session_sync_event_enablers(lttng_channel->session);
 691 end:
 692         return ret;
 693 }
 694
 695 static inline
 696 struct cds_hlist_head *borrow_hash_table_bucket(
 697                 struct cds_hlist_head *hash_table,
 698                 unsigned int hash_table_size,
 699                 const struct lttng_ust_event_desc *desc)
 700 {
 701         char name[LTTNG_UST_ABI_SYM_NAME_LEN];
 702         size_t name_len;
 703         uint32_t hash;
 704
 705         lttng_ust_format_event_name(desc, name);
 706         name_len = strlen(name);
 707
 708         hash = jhash(name, name_len, 0);
 709         return &hash_table[hash & (hash_table_size - 1)];
 710 }
 711
 712 /*
 713  * Supports event creation while tracing session is active.
 714  */
 715 static
 716 int lttng_event_recorder_create(const struct lttng_ust_event_desc *desc,
 717                 struct lttng_ust_channel_buffer *chan)
 718 {
 719         char name[LTTNG_UST_ABI_SYM_NAME_LEN];
 720         struct lttng_ust_event_recorder *event_recorder;
 721         struct lttng_ust_event_recorder_private *event_recorder_priv;
 722         struct lttng_ust_session *session = chan->parent->session;
 723         struct cds_hlist_head *head;
 724         int ret = 0;
 725         int notify_socket, loglevel;
 726         const char *uri;
 727
 728         head = borrow_hash_table_bucket(chan->parent->session->priv->events_ht.table,
 729                 LTTNG_UST_EVENT_HT_SIZE, desc);
 730
 731         notify_socket = lttng_get_notify_socket(session->priv->owner);
 732         if (notify_socket < 0) {
 733                 ret = notify_socket;
 734                 goto socket_error;
 735         }
 736
 737         ret = lttng_create_all_event_enums(desc->nr_fields, desc->fields,
 738                         session);
 739         if (ret < 0) {
 740                 DBG("Error (%d) adding enum to session", ret);
 741                 goto create_enum_error;
 742         }
 743
 744         /*
 745          * Check if loglevel match. Refuse to connect event if not.
 746          */
 747         event_recorder = zmalloc(sizeof(struct lttng_ust_event_recorder));
 748         if (!event_recorder) {
 749                 ret = -ENOMEM;
 750                 goto cache_error;
 751         }
 752         event_recorder->struct_size = sizeof(struct lttng_ust_event_recorder);
 753
 754         event_recorder->parent = zmalloc(sizeof(struct lttng_ust_event_common));
 755         if (!event_recorder->parent) {
 756                 ret = -ENOMEM;
 757                 goto parent_error;
 758         }
 759         event_recorder->parent->struct_size = sizeof(struct lttng_ust_event_common);
 760         event_recorder->parent->type = LTTNG_UST_EVENT_TYPE_RECORDER;
 761         event_recorder->parent->child = event_recorder;
 762
 763         event_recorder_priv = zmalloc(sizeof(struct lttng_ust_event_recorder_private));
 764         if (!event_recorder_priv) {
 765                 ret = -ENOMEM;
 766                 goto priv_error;
 767         }
 768         event_recorder->priv = event_recorder_priv;
 769         event_recorder_priv->pub = event_recorder;
 770         event_recorder->parent->priv = &event_recorder_priv->parent;
 771         event_recorder_priv->parent.pub = event_recorder->parent;
 772
 773         event_recorder->chan = chan;
 774
 775         /* Event will be enabled by enabler sync. */
 776         event_recorder->parent->run_filter = lttng_ust_interpret_event_filter;
 777         event_recorder->parent->enabled = 0;
 778         event_recorder->parent->priv->registered = 0;
 779         CDS_INIT_LIST_HEAD(&event_recorder->parent->priv->filter_bytecode_runtime_head);
 780         CDS_INIT_LIST_HEAD(&event_recorder->parent->priv->enablers_ref_head);
 781         event_recorder->parent->priv->desc = desc;
 782
 783         if (desc->loglevel)
 784                 loglevel = *(*event_recorder->parent->priv->desc->loglevel);
 785         else
 786                 loglevel = TRACE_DEFAULT;
 787         if (desc->model_emf_uri)
 788                 uri = *(desc->model_emf_uri);
 789         else
 790                 uri = NULL;
 791
 792         lttng_ust_format_event_name(desc, name);
 793
 794         /* Fetch event ID from sessiond */
 795         ret = ustcomm_register_event(notify_socket,
 796                 session,
 797                 session->priv->objd,
 798                 chan->priv->parent.objd,
 799                 name,
 800                 loglevel,
 801                 desc->signature,
 802                 desc->nr_fields,
 803                 desc->fields,
 804                 uri,
 805                 &event_recorder->priv->id);
 806         if (ret < 0) {
 807                 DBG("Error (%d) registering event to sessiond", ret);
 808                 goto sessiond_register_error;
 809         }
 810
 811         cds_list_add(&event_recorder_priv->node, &chan->parent->session->priv->events_head);
 812         cds_hlist_add_head(&event_recorder_priv->hlist, head);
 813         return 0;
 814
 815 sessiond_register_error:
 816         free(event_recorder_priv);
 817 priv_error:
 818         free(event_recorder->parent);
 819 parent_error:
 820         free(event_recorder);
 821 cache_error:
 822 create_enum_error:
 823 socket_error:
 824         return ret;
 825 }
 826
 827 static
 828 int lttng_event_notifier_create(const struct lttng_ust_event_desc *desc,
 829                 uint64_t token, uint64_t error_counter_index,
 830                 struct lttng_event_notifier_group *event_notifier_group)
 831 {
 832         struct lttng_ust_event_notifier *event_notifier;
 833         struct lttng_ust_event_notifier_private *event_notifier_priv;
 834         struct cds_hlist_head *head;
 835         int ret = 0;
 836
 837         /*
 838          * Get the hashtable bucket the created lttng_event_notifier object
 839          * should be inserted.
 840          */
 841         head = borrow_hash_table_bucket(
 842                 event_notifier_group->event_notifiers_ht.table,
 843                 LTTNG_UST_EVENT_NOTIFIER_HT_SIZE, desc);
 844
 845         event_notifier = zmalloc(sizeof(struct lttng_ust_event_notifier));
 846         if (!event_notifier) {
 847                 ret = -ENOMEM;
 848                 goto error;
 849         }
 850         event_notifier->struct_size = sizeof(struct lttng_ust_event_notifier);
 851
 852         event_notifier->parent = zmalloc(sizeof(struct lttng_ust_event_common));
 853         if (!event_notifier->parent) {
 854                 ret = -ENOMEM;
 855                 goto parent_error;
 856         }
 857         event_notifier->parent->struct_size = sizeof(struct lttng_ust_event_common);
 858         event_notifier->parent->type = LTTNG_UST_EVENT_TYPE_NOTIFIER;
 859         event_notifier->parent->child = event_notifier;
 860
 861         event_notifier_priv = zmalloc(sizeof(struct lttng_ust_event_notifier_private));
 862         if (!event_notifier_priv) {
 863                 ret = -ENOMEM;
 864                 goto priv_error;
 865         }
 866         event_notifier->priv = event_notifier_priv;
 867         event_notifier_priv->pub = event_notifier;
 868         event_notifier->parent->priv = &event_notifier_priv->parent;
 869         event_notifier_priv->parent.pub = event_notifier->parent;
 870
 871         event_notifier_priv->group = event_notifier_group;
 872         event_notifier_priv->parent.user_token = token;
 873         event_notifier_priv->error_counter_index = error_counter_index;
 874
 875         /* Event notifier will be enabled by enabler sync. */
 876         event_notifier->parent->run_filter = lttng_ust_interpret_event_filter;
 877         event_notifier->parent->enabled = 0;
 878         event_notifier_priv->parent.registered = 0;
 879
 880         CDS_INIT_LIST_HEAD(&event_notifier->parent->priv->filter_bytecode_runtime_head);
 881         CDS_INIT_LIST_HEAD(&event_notifier->priv->capture_bytecode_runtime_head);
 882         CDS_INIT_LIST_HEAD(&event_notifier_priv->parent.enablers_ref_head);
 883         event_notifier_priv->parent.desc = desc;
 884         event_notifier->notification_send = lttng_event_notifier_notification_send;
 885
 886         cds_list_add(&event_notifier_priv->node,
 887                         &event_notifier_group->event_notifiers_head);
 888         cds_hlist_add_head(&event_notifier_priv->hlist, head);
 889
 890         return 0;
 891
 892 priv_error:
 893         free(event_notifier->parent);
 894 parent_error:
 895         free(event_notifier);
 896 error:
 897         return ret;
 898 }
 899
 900 static
 901 int lttng_desc_match_star_glob_enabler(const struct lttng_ust_event_desc *desc,
 902                 struct lttng_enabler *enabler)
 903 {
 904         char name[LTTNG_UST_ABI_SYM_NAME_LEN];
 905         int loglevel = 0;
 906         unsigned int has_loglevel = 0;
 907
 908         lttng_ust_format_event_name(desc, name);
 909         assert(enabler->format_type == LTTNG_ENABLER_FORMAT_STAR_GLOB);
 910         if (!strutils_star_glob_match(enabler->event_param.name, SIZE_MAX,
 911                         name, SIZE_MAX))
 912                 return 0;
 913         if (desc->loglevel) {
 914                 loglevel = *(*desc->loglevel);
 915                 has_loglevel = 1;
 916         }
 917         if (!lttng_loglevel_match(loglevel,
 918                         has_loglevel,
 919                         enabler->event_param.loglevel_type,
 920                         enabler->event_param.loglevel))
 921                 return 0;
 922         return 1;
 923 }
 924
 925 static
 926 int lttng_desc_match_event_enabler(const struct lttng_ust_event_desc *desc,
 927                 struct lttng_enabler *enabler)
 928 {
 929         char name[LTTNG_UST_ABI_SYM_NAME_LEN];
 930         int loglevel = 0;
 931         unsigned int has_loglevel = 0;
 932
 933         lttng_ust_format_event_name(desc, name);
 934         assert(enabler->format_type == LTTNG_ENABLER_FORMAT_EVENT);
 935         if (strcmp(name, enabler->event_param.name))
 936                 return 0;
 937         if (desc->loglevel) {
 938                 loglevel = *(*desc->loglevel);
 939                 has_loglevel = 1;
 940         }
 941         if (!lttng_loglevel_match(loglevel,
 942                         has_loglevel,
 943                         enabler->event_param.loglevel_type,
 944                         enabler->event_param.loglevel))
 945                 return 0;
 946         return 1;
 947 }
 948
 949 static
 950 int lttng_desc_match_enabler(const struct lttng_ust_event_desc *desc,
 951                 struct lttng_enabler *enabler)
 952 {
 953         switch (enabler->format_type) {
 954         case LTTNG_ENABLER_FORMAT_STAR_GLOB:
 955         {
 956                 struct lttng_ust_excluder_node *excluder;
 957
 958                 if (!lttng_desc_match_star_glob_enabler(desc, enabler)) {
 959                         return 0;
 960                 }
 961
 962                 /*
 963                  * If the matching event matches with an excluder,
 964                  * return 'does not match'
 965                  */
 966                 cds_list_for_each_entry(excluder, &enabler->excluder_head, node) {
 967                         int count;
 968
 969                         for (count = 0; count < excluder->excluder.count; count++) {
 970                                 int len;
 971                                 char *excluder_name;
 972
 973                                 excluder_name = (char *) (excluder->excluder.names)
 974                                                 + count * LTTNG_UST_ABI_SYM_NAME_LEN;
 975                                 len = strnlen(excluder_name, LTTNG_UST_ABI_SYM_NAME_LEN);
 976                                 if (len > 0) {
 977                                         char name[LTTNG_UST_ABI_SYM_NAME_LEN];
 978
 979                                         lttng_ust_format_event_name(desc, name);
 980                                         if (strutils_star_glob_match(excluder_name, len, name, SIZE_MAX)) {
 981                                                 return 0;
 982                                         }
 983                                 }
 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_ust_event_recorder *event_recorder)
 998 {
 999         if (lttng_desc_match_enabler(event_recorder->parent->priv->desc,
1000                         lttng_event_enabler_as_enabler(event_enabler))
1001                         && event_recorder->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_ust_event_notifier *event_notifier)
1011 {
1012         int desc_matches = lttng_desc_match_enabler(event_notifier->priv->parent.desc,
1013                 lttng_event_notifier_enabler_as_enabler(event_notifier_enabler));
1014
1015         if (desc_matches && event_notifier->priv->group == event_notifier_enabler->group &&
1016                         event_notifier->priv->parent.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_recorder_if_missing(struct lttng_event_enabler *event_enabler)
1042 {
1043         struct lttng_ust_session *session = event_enabler->chan->parent->session;
1044         struct lttng_ust_registered_probe *reg_probe;
1045         const struct lttng_ust_event_desc *desc;
1046         struct lttng_ust_event_recorder_private *event_recorder_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(reg_probe, probe_list, head) {
1057                 const struct lttng_ust_probe_desc *probe_desc = reg_probe->desc;
1058
1059                 for (i = 0; i < probe_desc->nr_events; i++) {
1060                         int ret;
1061                         bool found = false;
1062                         struct cds_hlist_head *head;
1063                         struct cds_hlist_node *node;
1064
1065                         desc = probe_desc->event_desc[i];
1066                         if (!lttng_desc_match_enabler(desc,
1067                                         lttng_event_enabler_as_enabler(event_enabler)))
1068                                 continue;
1069
1070                         head = borrow_hash_table_bucket(
1071                                 session->priv->events_ht.table,
1072                                 LTTNG_UST_EVENT_HT_SIZE, desc);
1073
1074                         cds_hlist_for_each_entry(event_recorder_priv, node, head, hlist) {
1075                                 if (event_recorder_priv->parent.desc == desc
1076                                                 && event_recorder_priv->pub->chan == event_enabler->chan) {
1077                                         found = true;
1078                                         break;
1079                                 }
1080                         }
1081                         if (found)
1082                                 continue;
1083
1084                         /*
1085                          * We need to create an event for this
1086                          * event probe.
1087                          */
1088                         ret = lttng_event_recorder_create(probe_desc->event_desc[i],
1089                                         event_enabler->chan);
1090                         if (ret) {
1091                                 DBG("Unable to create event \"%s:%s\", error %d\n",
1092                                         probe_desc->provider_name,
1093                                         probe_desc->event_desc[i]->event_name, ret);
1094                         }
1095                 }
1096         }
1097 }
1098
1099 static
1100 void probe_provider_event_for_each(const struct lttng_ust_probe_desc *provider_desc,
1101                 void (*event_func)(struct lttng_ust_event_common *event))
1102 {
1103         struct cds_hlist_node *node, *tmp_node;
1104         struct cds_list_head *sessionsp;
1105         unsigned int i;
1106
1107         /* Get handle on list of sessions. */
1108         sessionsp = lttng_get_sessions();
1109
1110         /*
1111          * Iterate over all events in the probe provider descriptions and
1112          * sessions to queue the unregistration of the events.
1113          */
1114         for (i = 0; i < provider_desc->nr_events; i++) {
1115                 const struct lttng_ust_event_desc *event_desc;
1116                 struct lttng_event_notifier_group *event_notifier_group;
1117                 struct lttng_ust_event_recorder_private *event_recorder_priv;
1118                 struct lttng_ust_event_notifier_private *event_notifier_priv;
1119                 struct lttng_ust_session_private *session_priv;
1120                 struct cds_hlist_head *head;
1121
1122                 event_desc = provider_desc->event_desc[i];
1123
1124                 /*
1125                  * Iterate over all session to find the current event
1126                  * description.
1127                  */
1128                 cds_list_for_each_entry(session_priv, sessionsp, node) {
1129                         /*
1130                          * Get the list of events in the hashtable bucket and
1131                          * iterate to find the event matching this descriptor.
1132                          */
1133                         head = borrow_hash_table_bucket(
1134                                 session_priv->events_ht.table,
1135                                 LTTNG_UST_EVENT_HT_SIZE, event_desc);
1136
1137                         cds_hlist_for_each_entry_safe(event_recorder_priv, node, tmp_node, head, hlist) {
1138                                 if (event_desc == event_recorder_priv->parent.desc) {
1139                                         event_func(event_recorder_priv->parent.pub);
1140                                         break;
1141                                 }
1142                         }
1143                 }
1144
1145                 /*
1146                  * Iterate over all event_notifier groups to find the current event
1147                  * description.
1148                  */
1149                 cds_list_for_each_entry(event_notifier_group, &event_notifier_groups, node) {
1150                         /*
1151                          * Get the list of event_notifiers in the hashtable bucket and
1152                          * iterate to find the event_notifier matching this
1153                          * descriptor.
1154                          */
1155                         head = borrow_hash_table_bucket(
1156                                 event_notifier_group->event_notifiers_ht.table,
1157                                 LTTNG_UST_EVENT_NOTIFIER_HT_SIZE, event_desc);
1158
1159                         cds_hlist_for_each_entry_safe(event_notifier_priv, node, tmp_node, head, hlist) {
1160                                 if (event_desc == event_notifier_priv->parent.desc) {
1161                                         event_func(event_notifier_priv->parent.pub);
1162                                         break;
1163                                 }
1164                         }
1165                 }
1166         }
1167 }
1168
1169 static
1170 void _event_enum_destroy(struct lttng_ust_event_common *event)
1171 {
1172
1173         switch (event->type) {
1174         case LTTNG_UST_EVENT_TYPE_RECORDER:
1175         {
1176                 struct lttng_ust_event_recorder *event_recorder = event->child;
1177                 struct lttng_ust_session *session = event_recorder->chan->parent->session;
1178                 unsigned int i;
1179
1180                 /* Destroy enums of the current event. */
1181                 for (i = 0; i < event_recorder->parent->priv->desc->nr_fields; i++) {
1182                         const struct lttng_ust_enum_desc *enum_desc;
1183                         const struct lttng_ust_event_field *field;
1184                         struct lttng_enum *curr_enum;
1185
1186                         field = event_recorder->parent->priv->desc->fields[i];
1187                         switch (field->type->type) {
1188                         case lttng_ust_type_enum:
1189                                 enum_desc = lttng_ust_get_type_enum(field->type)->desc;
1190                                 break;
1191                         default:
1192                                 continue;
1193                         }
1194
1195                         curr_enum = lttng_ust_enum_get_from_desc(session, enum_desc);
1196                         if (curr_enum) {
1197                                 _lttng_enum_destroy(curr_enum);
1198                         }
1199                 }
1200                 break;
1201         }
1202         case LTTNG_UST_EVENT_TYPE_NOTIFIER:
1203                 break;
1204         default:
1205                 abort();
1206         }
1207         /* Destroy event. */
1208         _lttng_event_destroy(event);
1209 }
1210
1211 /*
1212  * Iterate over all the UST sessions to unregister and destroy all probes from
1213  * the probe provider descriptor received as argument. Must me called with the
1214  * ust_lock held.
1215  */
1216 void lttng_probe_provider_unregister_events(
1217                 const struct lttng_ust_probe_desc *provider_desc)
1218 {
1219         /*
1220          * Iterate over all events in the probe provider descriptions and sessions
1221          * to queue the unregistration of the events.
1222          */
1223         probe_provider_event_for_each(provider_desc, _lttng_event_unregister);
1224
1225         /* Wait for grace period. */
1226         lttng_ust_urcu_synchronize_rcu();
1227         /* Prune the unregistration queue. */
1228         lttng_ust_tp_probe_prune_release_queue();
1229
1230         /*
1231          * It is now safe to destroy the events and remove them from the event list
1232          * and hashtables.
1233          */
1234         probe_provider_event_for_each(provider_desc, _event_enum_destroy);
1235 }
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_event_recorders(struct lttng_event_enabler *event_enabler)
1243 {
1244         struct lttng_ust_session *session = event_enabler->chan->parent->session;
1245         struct lttng_ust_event_recorder_private *event_recorder_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_recorder_if_missing(event_enabler);
1252
1253         /* For each event matching enabler in session event list. */
1254         cds_list_for_each_entry(event_recorder_priv, &session->priv->events_head, node) {
1255                 struct lttng_enabler_ref *enabler_ref;
1256
1257                 if (!lttng_event_enabler_match_event(event_enabler, event_recorder_priv->pub))
1258                         continue;
1259
1260                 enabler_ref = lttng_enabler_ref(&event_recorder_priv->parent.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_recorder_priv->parent.enablers_ref_head);
1274                 }
1275
1276                 /*
1277                  * Link filter bytecodes if not linked yet.
1278                  */
1279                 lttng_enabler_link_bytecode(event_recorder_priv->parent.desc,
1280                         &session->priv->ctx,
1281                         &event_recorder_priv->parent.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 static
1344 void _lttng_event_destroy(struct lttng_ust_event_common *event)
1345 {
1346         struct lttng_enabler_ref *enabler_ref, *tmp_enabler_ref;
1347
1348         lttng_free_event_filter_runtime(event);
1349         /* Free event enabler refs */
1350         cds_list_for_each_entry_safe(enabler_ref, tmp_enabler_ref,
1351                         &event->priv->enablers_ref_head, node)
1352                 free(enabler_ref);
1353
1354         switch (event->type) {
1355         case LTTNG_UST_EVENT_TYPE_RECORDER:
1356         {
1357                 struct lttng_ust_event_recorder *event_recorder = event->child;
1358
1359                 /* Remove from event list. */
1360                 cds_list_del(&event_recorder->priv->node);
1361                 /* Remove from event hash table. */
1362                 cds_hlist_del(&event_recorder->priv->hlist);
1363
1364                 lttng_destroy_context(event_recorder->priv->ctx);
1365                 free(event_recorder->parent);
1366                 free(event_recorder->priv);
1367                 free(event_recorder);
1368                 break;
1369         }
1370         case LTTNG_UST_EVENT_TYPE_NOTIFIER:
1371         {
1372                 struct lttng_ust_event_notifier *event_notifier = event->child;
1373
1374                 /* Remove from event list. */
1375                 cds_list_del(&event_notifier->priv->node);
1376                 /* Remove from event hash table. */
1377                 cds_hlist_del(&event_notifier->priv->hlist);
1378
1379                 free(event_notifier->priv);
1380                 free(event_notifier->parent);
1381                 free(event_notifier);
1382                 break;
1383         }
1384         default:
1385                 abort();
1386         }
1387 }
1388
1389 static
1390 void _lttng_enum_destroy(struct lttng_enum *_enum)
1391 {
1392         cds_list_del(&_enum->node);
1393         cds_hlist_del(&_enum->hlist);
1394         free(_enum);
1395 }
1396
1397 void lttng_ust_abi_events_exit(void)
1398 {
1399         struct lttng_ust_session_private *session_priv, *tmpsession_priv;
1400
1401         cds_list_for_each_entry_safe(session_priv, tmpsession_priv, &sessions, node)
1402                 lttng_session_destroy(session_priv->pub);
1403 }
1404
1405 /*
1406  * Enabler management.
1407  */
1408 struct lttng_event_enabler *lttng_event_enabler_create(
1409                 enum lttng_enabler_format_type format_type,
1410                 struct lttng_ust_abi_event *event_param,
1411                 struct lttng_ust_channel_buffer *chan)
1412 {
1413         struct lttng_event_enabler *event_enabler;
1414
1415         event_enabler = zmalloc(sizeof(*event_enabler));
1416         if (!event_enabler)
1417                 return NULL;
1418         event_enabler->base.format_type = format_type;
1419         CDS_INIT_LIST_HEAD(&event_enabler->base.filter_bytecode_head);
1420         CDS_INIT_LIST_HEAD(&event_enabler->base.excluder_head);
1421         memcpy(&event_enabler->base.event_param, event_param,
1422                 sizeof(event_enabler->base.event_param));
1423         event_enabler->chan = chan;
1424         /* ctx left NULL */
1425         event_enabler->base.enabled = 0;
1426         cds_list_add(&event_enabler->node, &event_enabler->chan->parent->session->priv->enablers_head);
1427         lttng_session_lazy_sync_event_enablers(event_enabler->chan->parent->session);
1428
1429         return event_enabler;
1430 }
1431
1432 struct lttng_event_notifier_enabler *lttng_event_notifier_enabler_create(
1433                 struct lttng_event_notifier_group *event_notifier_group,
1434                 enum lttng_enabler_format_type format_type,
1435                 struct lttng_ust_abi_event_notifier *event_notifier_param)
1436 {
1437         struct lttng_event_notifier_enabler *event_notifier_enabler;
1438
1439         event_notifier_enabler = zmalloc(sizeof(*event_notifier_enabler));
1440         if (!event_notifier_enabler)
1441                 return NULL;
1442         event_notifier_enabler->base.format_type = format_type;
1443         CDS_INIT_LIST_HEAD(&event_notifier_enabler->base.filter_bytecode_head);
1444         CDS_INIT_LIST_HEAD(&event_notifier_enabler->capture_bytecode_head);
1445         CDS_INIT_LIST_HEAD(&event_notifier_enabler->base.excluder_head);
1446
1447         event_notifier_enabler->user_token = event_notifier_param->event.token;
1448         event_notifier_enabler->error_counter_index = event_notifier_param->error_counter_index;
1449         event_notifier_enabler->num_captures = 0;
1450
1451         memcpy(&event_notifier_enabler->base.event_param.name,
1452                 event_notifier_param->event.name,
1453                 sizeof(event_notifier_enabler->base.event_param.name));
1454         event_notifier_enabler->base.event_param.instrumentation =
1455                 event_notifier_param->event.instrumentation;
1456         event_notifier_enabler->base.event_param.loglevel =
1457                 event_notifier_param->event.loglevel;
1458         event_notifier_enabler->base.event_param.loglevel_type =
1459                 event_notifier_param->event.loglevel_type;
1460
1461         event_notifier_enabler->base.enabled = 0;
1462         event_notifier_enabler->group = event_notifier_group;
1463
1464         cds_list_add(&event_notifier_enabler->node,
1465                         &event_notifier_group->enablers_head);
1466
1467         lttng_event_notifier_group_sync_enablers(event_notifier_group);
1468
1469         return event_notifier_enabler;
1470 }
1471
1472 int lttng_event_enabler_enable(struct lttng_event_enabler *event_enabler)
1473 {
1474         lttng_event_enabler_as_enabler(event_enabler)->enabled = 1;
1475         lttng_session_lazy_sync_event_enablers(event_enabler->chan->parent->session);
1476
1477         return 0;
1478 }
1479
1480 int lttng_event_enabler_disable(struct lttng_event_enabler *event_enabler)
1481 {
1482         lttng_event_enabler_as_enabler(event_enabler)->enabled = 0;
1483         lttng_session_lazy_sync_event_enablers(event_enabler->chan->parent->session);
1484
1485         return 0;
1486 }
1487
1488 static
1489 void _lttng_enabler_attach_filter_bytecode(struct lttng_enabler *enabler,
1490                 struct lttng_ust_bytecode_node **bytecode)
1491 {
1492         (*bytecode)->enabler = enabler;
1493         cds_list_add_tail(&(*bytecode)->node, &enabler->filter_bytecode_head);
1494         /* Take ownership of bytecode */
1495         *bytecode = NULL;
1496 }
1497
1498 int lttng_event_enabler_attach_filter_bytecode(struct lttng_event_enabler *event_enabler,
1499                 struct lttng_ust_bytecode_node **bytecode)
1500 {
1501         _lttng_enabler_attach_filter_bytecode(
1502                 lttng_event_enabler_as_enabler(event_enabler), bytecode);
1503
1504         lttng_session_lazy_sync_event_enablers(event_enabler->chan->parent->session);
1505         return 0;
1506 }
1507
1508 static
1509 void _lttng_enabler_attach_exclusion(struct lttng_enabler *enabler,
1510                 struct lttng_ust_excluder_node **excluder)
1511 {
1512         (*excluder)->enabler = enabler;
1513         cds_list_add_tail(&(*excluder)->node, &enabler->excluder_head);
1514         /* Take ownership of excluder */
1515         *excluder = NULL;
1516 }
1517
1518 int lttng_event_enabler_attach_exclusion(struct lttng_event_enabler *event_enabler,
1519                 struct lttng_ust_excluder_node **excluder)
1520 {
1521         _lttng_enabler_attach_exclusion(
1522                 lttng_event_enabler_as_enabler(event_enabler), excluder);
1523
1524         lttng_session_lazy_sync_event_enablers(event_enabler->chan->parent->session);
1525         return 0;
1526 }
1527
1528 int lttng_event_notifier_enabler_enable(
1529                 struct lttng_event_notifier_enabler *event_notifier_enabler)
1530 {
1531         lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->enabled = 1;
1532         lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
1533
1534         return 0;
1535 }
1536
1537 int lttng_event_notifier_enabler_disable(
1538                 struct lttng_event_notifier_enabler *event_notifier_enabler)
1539 {
1540         lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->enabled = 0;
1541         lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
1542
1543         return 0;
1544 }
1545
1546 int lttng_event_notifier_enabler_attach_filter_bytecode(
1547                 struct lttng_event_notifier_enabler *event_notifier_enabler,
1548                 struct lttng_ust_bytecode_node **bytecode)
1549 {
1550         _lttng_enabler_attach_filter_bytecode(
1551                 lttng_event_notifier_enabler_as_enabler(event_notifier_enabler),
1552                 bytecode);
1553
1554         lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
1555         return 0;
1556 }
1557
1558 int lttng_event_notifier_enabler_attach_capture_bytecode(
1559                 struct lttng_event_notifier_enabler *event_notifier_enabler,
1560                 struct lttng_ust_bytecode_node **bytecode)
1561 {
1562         (*bytecode)->enabler = lttng_event_notifier_enabler_as_enabler(
1563                         event_notifier_enabler);
1564         cds_list_add_tail(&(*bytecode)->node,
1565                         &event_notifier_enabler->capture_bytecode_head);
1566         /* Take ownership of bytecode */
1567         *bytecode = NULL;
1568         event_notifier_enabler->num_captures++;
1569
1570         lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
1571         return 0;
1572 }
1573
1574 int lttng_event_notifier_enabler_attach_exclusion(
1575                 struct lttng_event_notifier_enabler *event_notifier_enabler,
1576                 struct lttng_ust_excluder_node **excluder)
1577 {
1578         _lttng_enabler_attach_exclusion(
1579                 lttng_event_notifier_enabler_as_enabler(event_notifier_enabler),
1580                 excluder);
1581
1582         lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
1583         return 0;
1584 }
1585
1586 int lttng_attach_context(struct lttng_ust_abi_context *context_param,
1587                 union lttng_ust_abi_args *uargs,
1588                 struct lttng_ust_ctx **ctx, struct lttng_ust_session *session)
1589 {
1590         /*
1591          * We cannot attach a context after trace has been started for a
1592          * session because the metadata does not allow expressing this
1593          * information outside of the original channel scope.
1594          */
1595         if (session->priv->been_active)
1596                 return -EPERM;
1597
1598         switch (context_param->ctx) {
1599         case LTTNG_UST_ABI_CONTEXT_PTHREAD_ID:
1600                 return lttng_add_pthread_id_to_ctx(ctx);
1601         case LTTNG_UST_ABI_CONTEXT_PERF_THREAD_COUNTER:
1602         {
1603                 struct lttng_ust_abi_perf_counter_ctx *perf_ctx_param;
1604
1605                 perf_ctx_param = &context_param->u.perf_counter;
1606                 return lttng_add_perf_counter_to_ctx(
1607                         perf_ctx_param->type,
1608                         perf_ctx_param->config,
1609                         perf_ctx_param->name,
1610                         ctx);
1611         }
1612         case LTTNG_UST_ABI_CONTEXT_VTID:
1613                 return lttng_add_vtid_to_ctx(ctx);
1614         case LTTNG_UST_ABI_CONTEXT_VPID:
1615                 return lttng_add_vpid_to_ctx(ctx);
1616         case LTTNG_UST_ABI_CONTEXT_PROCNAME:
1617                 return lttng_add_procname_to_ctx(ctx);
1618         case LTTNG_UST_ABI_CONTEXT_IP:
1619                 return lttng_add_ip_to_ctx(ctx);
1620         case LTTNG_UST_ABI_CONTEXT_CPU_ID:
1621                 return lttng_add_cpu_id_to_ctx(ctx);
1622         case LTTNG_UST_ABI_CONTEXT_APP_CONTEXT:
1623                 return lttng_ust_add_app_context_to_ctx_rcu(uargs->app_context.ctxname,
1624                         ctx);
1625         case LTTNG_UST_ABI_CONTEXT_CGROUP_NS:
1626                 return lttng_add_cgroup_ns_to_ctx(ctx);
1627         case LTTNG_UST_ABI_CONTEXT_IPC_NS:
1628                 return lttng_add_ipc_ns_to_ctx(ctx);
1629         case LTTNG_UST_ABI_CONTEXT_MNT_NS:
1630                 return lttng_add_mnt_ns_to_ctx(ctx);
1631         case LTTNG_UST_ABI_CONTEXT_NET_NS:
1632                 return lttng_add_net_ns_to_ctx(ctx);
1633         case LTTNG_UST_ABI_CONTEXT_PID_NS:
1634                 return lttng_add_pid_ns_to_ctx(ctx);
1635         case LTTNG_UST_ABI_CONTEXT_TIME_NS:
1636                 return lttng_add_time_ns_to_ctx(ctx);
1637         case LTTNG_UST_ABI_CONTEXT_USER_NS:
1638                 return lttng_add_user_ns_to_ctx(ctx);
1639         case LTTNG_UST_ABI_CONTEXT_UTS_NS:
1640                 return lttng_add_uts_ns_to_ctx(ctx);
1641         case LTTNG_UST_ABI_CONTEXT_VUID:
1642                 return lttng_add_vuid_to_ctx(ctx);
1643         case LTTNG_UST_ABI_CONTEXT_VEUID:
1644                 return lttng_add_veuid_to_ctx(ctx);
1645         case LTTNG_UST_ABI_CONTEXT_VSUID:
1646                 return lttng_add_vsuid_to_ctx(ctx);
1647         case LTTNG_UST_ABI_CONTEXT_VGID:
1648                 return lttng_add_vgid_to_ctx(ctx);
1649         case LTTNG_UST_ABI_CONTEXT_VEGID:
1650                 return lttng_add_vegid_to_ctx(ctx);
1651         case LTTNG_UST_ABI_CONTEXT_VSGID:
1652                 return lttng_add_vsgid_to_ctx(ctx);
1653         default:
1654                 return -EINVAL;
1655         }
1656 }
1657
1658 int lttng_event_enabler_attach_context(
1659                 struct lttng_event_enabler *enabler __attribute__((unused)),
1660                 struct lttng_ust_abi_context *context_param __attribute__((unused)))
1661 {
1662         return -ENOSYS;
1663 }
1664
1665 void lttng_event_enabler_destroy(struct lttng_event_enabler *event_enabler)
1666 {
1667         if (!event_enabler) {
1668                 return;
1669         }
1670         cds_list_del(&event_enabler->node);
1671
1672         lttng_enabler_destroy(lttng_event_enabler_as_enabler(event_enabler));
1673
1674         lttng_destroy_context(event_enabler->ctx);
1675         free(event_enabler);
1676 }
1677
1678 /*
1679  * lttng_session_sync_event_enablers should be called just before starting a
1680  * session.
1681  */
1682 static
1683 void lttng_session_sync_event_enablers(struct lttng_ust_session *session)
1684 {
1685         struct lttng_event_enabler *event_enabler;
1686         struct lttng_ust_event_recorder_private *event_recorder_priv;
1687
1688         cds_list_for_each_entry(event_enabler, &session->priv->enablers_head, node)
1689                 lttng_event_enabler_ref_event_recorders(event_enabler);
1690         /*
1691          * For each event, if at least one of its enablers is enabled,
1692          * and its channel and session transient states are enabled, we
1693          * enable the event, else we disable it.
1694          */
1695         cds_list_for_each_entry(event_recorder_priv, &session->priv->events_head, node) {
1696                 struct lttng_enabler_ref *enabler_ref;
1697                 struct lttng_ust_bytecode_runtime *runtime;
1698                 int enabled = 0, has_enablers_without_filter_bytecode = 0;
1699                 int nr_filters = 0;
1700
1701                 /* Enable events */
1702                 cds_list_for_each_entry(enabler_ref,
1703                                 &event_recorder_priv->parent.enablers_ref_head, node) {
1704                         if (enabler_ref->ref->enabled) {
1705                                 enabled = 1;
1706                                 break;
1707                         }
1708                 }
1709                 /*
1710                  * Enabled state is based on union of enablers, with
1711                  * intesection of session and channel transient enable
1712                  * states.
1713                  */
1714                 enabled = enabled && session->priv->tstate && event_recorder_priv->pub->chan->priv->parent.tstate;
1715
1716                 CMM_STORE_SHARED(event_recorder_priv->pub->parent->enabled, enabled);
1717                 /*
1718                  * Sync tracepoint registration with event enabled
1719                  * state.
1720                  */
1721                 if (enabled) {
1722                         if (!event_recorder_priv->parent.registered)
1723                                 register_event(event_recorder_priv->parent.pub);
1724                 } else {
1725                         if (event_recorder_priv->parent.registered)
1726                                 unregister_event(event_recorder_priv->parent.pub);
1727                 }
1728
1729                 /* Check if has enablers without bytecode enabled */
1730                 cds_list_for_each_entry(enabler_ref,
1731                                 &event_recorder_priv->parent.enablers_ref_head, node) {
1732                         if (enabler_ref->ref->enabled
1733                                         && cds_list_empty(&enabler_ref->ref->filter_bytecode_head)) {
1734                                 has_enablers_without_filter_bytecode = 1;
1735                                 break;
1736                         }
1737                 }
1738                 event_recorder_priv->parent.has_enablers_without_filter_bytecode =
1739                         has_enablers_without_filter_bytecode;
1740
1741                 /* Enable filters */
1742                 cds_list_for_each_entry(runtime,
1743                                 &event_recorder_priv->parent.filter_bytecode_runtime_head, node) {
1744                         lttng_bytecode_sync_state(runtime);
1745                         nr_filters++;
1746                 }
1747                 CMM_STORE_SHARED(event_recorder_priv->parent.pub->eval_filter,
1748                         !(has_enablers_without_filter_bytecode || !nr_filters));
1749         }
1750         lttng_ust_tp_probe_prune_release_queue();
1751 }
1752
1753 /* Support for event notifier is introduced by probe provider major version 2. */
1754 static
1755 bool lttng_ust_probe_supports_event_notifier(const struct lttng_ust_probe_desc *probe_desc)
1756 {
1757         return probe_desc->major >= 2;
1758 }
1759
1760 static
1761 void lttng_create_event_notifier_if_missing(
1762                 struct lttng_event_notifier_enabler *event_notifier_enabler)
1763 {
1764         struct lttng_event_notifier_group *event_notifier_group = event_notifier_enabler->group;
1765         struct lttng_ust_registered_probe *reg_probe;
1766         struct cds_list_head *probe_list;
1767         int i;
1768
1769         probe_list = lttng_get_probe_list_head();
1770
1771         cds_list_for_each_entry(reg_probe, probe_list, head) {
1772                 const struct lttng_ust_probe_desc *probe_desc = reg_probe->desc;
1773
1774                 for (i = 0; i < probe_desc->nr_events; i++) {
1775                         int ret;
1776                         bool found = false;
1777                         const struct lttng_ust_event_desc *desc;
1778                         struct lttng_ust_event_notifier_private *event_notifier_priv;
1779                         struct cds_hlist_head *head;
1780                         struct cds_hlist_node *node;
1781
1782                         desc = probe_desc->event_desc[i];
1783
1784                         if (!lttng_desc_match_enabler(desc,
1785                                         lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)))
1786                                 continue;
1787
1788                         /*
1789                          * Given the current event_notifier group, get the bucket that
1790                          * the target event_notifier would be if it was already
1791                          * created.
1792                          */
1793                         head = borrow_hash_table_bucket(
1794                                 event_notifier_group->event_notifiers_ht.table,
1795                                 LTTNG_UST_EVENT_NOTIFIER_HT_SIZE, desc);
1796
1797                         cds_hlist_for_each_entry(event_notifier_priv, node, head, hlist) {
1798                                 /*
1799                                  * Check if event_notifier already exists by checking
1800                                  * if the event_notifier and enabler share the same
1801                                  * description and id.
1802                                  */
1803                                 if (event_notifier_priv->parent.desc == desc &&
1804                                                 event_notifier_priv->parent.user_token == event_notifier_enabler->user_token) {
1805                                         found = true;
1806                                         break;
1807                                 }
1808                         }
1809
1810                         if (found)
1811                                 continue;
1812
1813                         /* Check that the probe supports event notifiers, else report the error. */
1814                         if (!lttng_ust_probe_supports_event_notifier(probe_desc)) {
1815                                 ERR("Probe \"%s\" contains event \"%s:%s\" which matches an enabled event notifier, "
1816                                         "but its version (%u.%u) is too old and does not implement event notifiers. "
1817                                         "It needs to be recompiled against a newer version of LTTng-UST, otherwise "
1818                                         "this event will not generate any notification.",
1819                                         probe_desc->provider_name,
1820                                         probe_desc->provider_name, desc->event_name,
1821                                         probe_desc->major,
1822                                         probe_desc->minor);
1823                                 continue;
1824                         }
1825                         /*
1826                          * We need to create a event_notifier for this event probe.
1827                          */
1828                         ret = lttng_event_notifier_create(desc,
1829                                 event_notifier_enabler->user_token,
1830                                 event_notifier_enabler->error_counter_index,
1831                                 event_notifier_group);
1832                         if (ret) {
1833                                 DBG("Unable to create event_notifier \"%s:%s\", error %d\n",
1834                                         probe_desc->provider_name,
1835                                         probe_desc->event_desc[i]->event_name, ret);
1836                         }
1837                 }
1838         }
1839 }
1840
1841 /*
1842  * Create event_notifiers associated with a event_notifier enabler (if not already present).
1843  */
1844 static
1845 int lttng_event_notifier_enabler_ref_event_notifiers(
1846                 struct lttng_event_notifier_enabler *event_notifier_enabler)
1847 {
1848         struct lttng_event_notifier_group *event_notifier_group = event_notifier_enabler->group;
1849         struct lttng_ust_event_notifier_private *event_notifier_priv;
1850
1851          /*
1852           * Only try to create event_notifiers for enablers that are enabled, the user
1853           * might still be attaching filter or exclusion to the
1854           * event_notifier_enabler.
1855           */
1856         if (!lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->enabled)
1857                 goto end;
1858
1859         /* First, ensure that probe event_notifiers are created for this enabler. */
1860         lttng_create_event_notifier_if_missing(event_notifier_enabler);
1861
1862         /* Link the created event_notifier with its associated enabler. */
1863         cds_list_for_each_entry(event_notifier_priv, &event_notifier_group->event_notifiers_head, node) {
1864                 struct lttng_enabler_ref *enabler_ref;
1865
1866                 if (!lttng_event_notifier_enabler_match_event_notifier(event_notifier_enabler, event_notifier_priv->pub))
1867                         continue;
1868
1869                 enabler_ref = lttng_enabler_ref(&event_notifier_priv->parent.enablers_ref_head,
1870                         lttng_event_notifier_enabler_as_enabler(event_notifier_enabler));
1871                 if (!enabler_ref) {
1872                         /*
1873                          * If no backward ref, create it.
1874                          * Add backward ref from event_notifier to enabler.
1875                          */
1876                         enabler_ref = zmalloc(sizeof(*enabler_ref));
1877                         if (!enabler_ref)
1878                                 return -ENOMEM;
1879
1880                         enabler_ref->ref = lttng_event_notifier_enabler_as_enabler(
1881                                 event_notifier_enabler);
1882                         cds_list_add(&enabler_ref->node,
1883                                 &event_notifier_priv->parent.enablers_ref_head);
1884                 }
1885
1886                 /*
1887                  * Link filter bytecodes if not linked yet.
1888                  */
1889                 lttng_enabler_link_bytecode(event_notifier_priv->parent.desc,
1890                         &event_notifier_group->ctx,
1891                         &event_notifier_priv->parent.filter_bytecode_runtime_head,
1892                         &lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->filter_bytecode_head);
1893
1894                 /*
1895                  * Link capture bytecodes if not linked yet.
1896                  */
1897                 lttng_enabler_link_bytecode(event_notifier_priv->parent.desc,
1898                         &event_notifier_group->ctx, &event_notifier_priv->capture_bytecode_runtime_head,
1899                         &event_notifier_enabler->capture_bytecode_head);
1900
1901                 event_notifier_priv->num_captures = event_notifier_enabler->num_captures;
1902         }
1903 end:
1904         return 0;
1905 }
1906
1907 static
1908 void lttng_event_notifier_group_sync_enablers(struct lttng_event_notifier_group *event_notifier_group)
1909 {
1910         struct lttng_event_notifier_enabler *event_notifier_enabler;
1911         struct lttng_ust_event_notifier_private *event_notifier_priv;
1912
1913         cds_list_for_each_entry(event_notifier_enabler, &event_notifier_group->enablers_head, node)
1914                 lttng_event_notifier_enabler_ref_event_notifiers(event_notifier_enabler);
1915
1916         /*
1917          * For each event_notifier, if at least one of its enablers is enabled,
1918          * we enable the event_notifier, else we disable it.
1919          */
1920         cds_list_for_each_entry(event_notifier_priv, &event_notifier_group->event_notifiers_head, node) {
1921                 struct lttng_enabler_ref *enabler_ref;
1922                 struct lttng_ust_bytecode_runtime *runtime;
1923                 int enabled = 0, has_enablers_without_filter_bytecode = 0;
1924                 int nr_filters = 0, nr_captures = 0;
1925
1926                 /* Enable event_notifiers */
1927                 cds_list_for_each_entry(enabler_ref,
1928                                 &event_notifier_priv->parent.enablers_ref_head, node) {
1929                         if (enabler_ref->ref->enabled) {
1930                                 enabled = 1;
1931                                 break;
1932                         }
1933                 }
1934
1935                 CMM_STORE_SHARED(event_notifier_priv->pub->parent->enabled, enabled);
1936                 /*
1937                  * Sync tracepoint registration with event_notifier enabled
1938                  * state.
1939                  */
1940                 if (enabled) {
1941                         if (!event_notifier_priv->parent.registered)
1942                                 register_event(event_notifier_priv->parent.pub);
1943                 } else {
1944                         if (event_notifier_priv->parent.registered)
1945                                 unregister_event(event_notifier_priv->parent.pub);
1946                 }
1947
1948                 /* Check if has enablers without bytecode enabled */
1949                 cds_list_for_each_entry(enabler_ref,
1950                                 &event_notifier_priv->parent.enablers_ref_head, node) {
1951                         if (enabler_ref->ref->enabled
1952                                         && cds_list_empty(&enabler_ref->ref->filter_bytecode_head)) {
1953                                 has_enablers_without_filter_bytecode = 1;
1954                                 break;
1955                         }
1956                 }
1957                 event_notifier_priv->parent.has_enablers_without_filter_bytecode =
1958                         has_enablers_without_filter_bytecode;
1959
1960                 /* Enable filters */
1961                 cds_list_for_each_entry(runtime,
1962                                 &event_notifier_priv->parent.filter_bytecode_runtime_head, node) {
1963                         lttng_bytecode_sync_state(runtime);
1964                         nr_filters++;
1965                 }
1966                 CMM_STORE_SHARED(event_notifier_priv->parent.pub->eval_filter,
1967                         !(has_enablers_without_filter_bytecode || !nr_filters));
1968
1969                 /* Enable captures. */
1970                 cds_list_for_each_entry(runtime,
1971                                 &event_notifier_priv->capture_bytecode_runtime_head, node) {
1972                         lttng_bytecode_sync_state(runtime);
1973                         nr_captures++;
1974                 }
1975                 CMM_STORE_SHARED(event_notifier_priv->pub->eval_capture,
1976                                 !!nr_captures);
1977         }
1978         lttng_ust_tp_probe_prune_release_queue();
1979 }
1980
1981 /*
1982  * Apply enablers to session events, adding events to session if need
1983  * be. It is required after each modification applied to an active
1984  * session, and right before session "start".
1985  * "lazy" sync means we only sync if required.
1986  */
1987 static
1988 void lttng_session_lazy_sync_event_enablers(struct lttng_ust_session *session)
1989 {
1990         /* We can skip if session is not active */
1991         if (!session->active)
1992                 return;
1993         lttng_session_sync_event_enablers(session);
1994 }
1995
1996 /*
1997  * Update all sessions with the given app context.
1998  * Called with ust lock held.
1999  * This is invoked when an application context gets loaded/unloaded. It
2000  * ensures the context callbacks are in sync with the application
2001  * context (either app context callbacks, or dummy callbacks).
2002  */
2003 void lttng_ust_context_set_session_provider(const char *name,
2004                 size_t (*get_size)(void *priv, size_t offset),
2005                 void (*record)(void *priv, struct lttng_ust_lib_ring_buffer_ctx *ctx,
2006                         struct lttng_ust_channel_buffer *chan),
2007                 void (*get_value)(void *priv, struct lttng_ust_ctx_value *value),
2008                 void *priv)
2009 {
2010         struct lttng_ust_session_private *session_priv;
2011
2012         cds_list_for_each_entry(session_priv, &sessions, node) {
2013                 struct lttng_ust_channel_buffer_private *chan;
2014                 struct lttng_ust_event_recorder_private *event_recorder_priv;
2015                 int ret;
2016
2017                 ret = lttng_ust_context_set_provider_rcu(&session_priv->ctx,
2018                                 name, get_size, record, get_value, priv);
2019                 if (ret)
2020                         abort();
2021                 cds_list_for_each_entry(chan, &session_priv->chan_head, node) {
2022                         ret = lttng_ust_context_set_provider_rcu(&chan->ctx,
2023                                         name, get_size, record, get_value, priv);
2024                         if (ret)
2025                                 abort();
2026                 }
2027                 cds_list_for_each_entry(event_recorder_priv, &session_priv->events_head, node) {
2028                         ret = lttng_ust_context_set_provider_rcu(&event_recorder_priv->ctx,
2029                                         name, get_size, record, get_value, priv);
2030                         if (ret)
2031                                 abort();
2032                 }
2033         }
2034 }
2035
2036 /*
2037  * Update all event_notifier groups with the given app context.
2038  * Called with ust lock held.
2039  * This is invoked when an application context gets loaded/unloaded. It
2040  * ensures the context callbacks are in sync with the application
2041  * context (either app context callbacks, or dummy callbacks).
2042  */
2043 void lttng_ust_context_set_event_notifier_group_provider(const char *name,
2044                 size_t (*get_size)(void *priv, size_t offset),
2045                 void (*record)(void *priv, struct lttng_ust_lib_ring_buffer_ctx *ctx,
2046                         struct lttng_ust_channel_buffer *chan),
2047                 void (*get_value)(void *priv, struct lttng_ust_ctx_value *value),
2048                 void *priv)
2049 {
2050         struct lttng_event_notifier_group *event_notifier_group;
2051
2052         cds_list_for_each_entry(event_notifier_group, &event_notifier_groups, node) {
2053                 int ret;
2054
2055                 ret = lttng_ust_context_set_provider_rcu(
2056                                 &event_notifier_group->ctx,
2057                                 name, get_size, record, get_value, priv);
2058                 if (ret)
2059                         abort();
2060         }
2061 }
2062
2063 int lttng_ust_session_uuid_validate(struct lttng_ust_session *session,
2064                 unsigned char *uuid)
2065 {
2066         if (!session)
2067                 return 0;
2068         /* Compare UUID with session. */
2069         if (session->priv->uuid_set) {
2070                 if (memcmp(session->priv->uuid, uuid, LTTNG_UST_UUID_LEN)) {
2071                         return -1;
2072                 }
2073         } else {
2074                 memcpy(session->priv->uuid, uuid, LTTNG_UST_UUID_LEN);
2075                 session->priv->uuid_set = true;
2076         }
2077         return 0;
2078
2079 }