liblttng-ust/lttng-events.c

   1 /*
   2  * lttng-events.c
   3  *
   4  * Holds LTTng per-session event registry.
   5  *
   6  * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #define _GNU_SOURCE
  24 #define _LGPL_SOURCE
  25 #include <stdio.h>
  26 #include <urcu/list.h>
  27 #include <urcu/hlist.h>
  28 #include <pthread.h>
  29 #include <errno.h>
  30 #include <sys/shm.h>
  31 #include <sys/ipc.h>
  32 #include <stdint.h>
  33 #include <stddef.h>
  34 #include <inttypes.h>
  35 #include <time.h>
  36 #include <stdbool.h>
  37 #include <lttng/ust-endian.h>
  38 #include "clock.h"
  39
  40 #include <urcu-bp.h>
  41 #include <urcu/compiler.h>
  42 #include <urcu/uatomic.h>
  43 #include <urcu/arch.h>
  44
  45 #include <lttng/tracepoint.h>
  46 #include <lttng/ust-events.h>
  47
  48 #include <usterr-signal-safe.h>
  49 #include <helper.h>
  50 #include <lttng/ust-ctl.h>
  51 #include <ust-comm.h>
  52 #include <lttng/ust-dynamic-type.h>
  53 #include <lttng/ust-context-provider.h>
  54 #include "error.h"
  55 #include "compat.h"
  56 #include "lttng-ust-uuid.h"
  57
  58 #include "tracepoint-internal.h"
  59 #include "string-utils.h"
  60 #include "lttng-tracer.h"
  61 #include "lttng-tracer-core.h"
  62 #include "lttng-ust-statedump.h"
  63 #include "wait.h"
  64 #include "../libringbuffer/shm.h"
  65 #include "jhash.h"
  66
  67 /*
  68  * All operations within this file are called by the communication
  69  * thread, under ust_lock protection.
  70  */
  71
  72 static CDS_LIST_HEAD(sessions);
  73
  74 struct cds_list_head *_lttng_get_sessions(void)
  75 {
  76         return &sessions;
  77 }
  78
  79 static void _lttng_event_destroy(struct lttng_event *event);
  80 static void _lttng_enum_destroy(struct lttng_enum *_enum);
  81
  82 static
  83 void lttng_session_lazy_sync_enablers(struct lttng_session *session);
  84 static
  85 void lttng_session_sync_enablers(struct lttng_session *session);
  86 static
  87 void lttng_enabler_destroy(struct lttng_enabler *enabler);
  88
  89 /*
  90  * Called with ust lock held.
  91  */
  92 int lttng_session_active(void)
  93 {
  94         struct lttng_session *iter;
  95
  96         cds_list_for_each_entry(iter, &sessions, node) {
  97                 if (iter->active)
  98                         return 1;
  99         }
 100         return 0;
 101 }
 102
 103 static
 104 int lttng_loglevel_match(int loglevel,
 105                 unsigned int has_loglevel,
 106                 enum lttng_ust_loglevel_type req_type,
 107                 int req_loglevel)
 108 {
 109         if (!has_loglevel)
 110                 loglevel = TRACE_DEFAULT;
 111         switch (req_type) {
 112         case LTTNG_UST_LOGLEVEL_RANGE:
 113                 if (loglevel <= req_loglevel
 114                                 || (req_loglevel == -1 && loglevel <= TRACE_DEBUG))
 115                         return 1;
 116                 else
 117                         return 0;
 118         case LTTNG_UST_LOGLEVEL_SINGLE:
 119                 if (loglevel == req_loglevel
 120                                 || (req_loglevel == -1 && loglevel <= TRACE_DEBUG))
 121                         return 1;
 122                 else
 123                         return 0;
 124         case LTTNG_UST_LOGLEVEL_ALL:
 125         default:
 126                 if (loglevel <= TRACE_DEBUG)
 127                         return 1;
 128                 else
 129                         return 0;
 130         }
 131 }
 132
 133 void synchronize_trace(void)
 134 {
 135         synchronize_rcu();
 136 }
 137
 138 struct lttng_session *lttng_session_create(void)
 139 {
 140         struct lttng_session *session;
 141         int i;
 142
 143         session = zmalloc(sizeof(struct lttng_session));
 144         if (!session)
 145                 return NULL;
 146         if (lttng_session_context_init(&session->ctx)) {
 147                 free(session);
 148                 return NULL;
 149         }
 150         CDS_INIT_LIST_HEAD(&session->chan_head);
 151         CDS_INIT_LIST_HEAD(&session->events_head);
 152         CDS_INIT_LIST_HEAD(&session->enums_head);
 153         CDS_INIT_LIST_HEAD(&session->enablers_head);
 154         for (i = 0; i < LTTNG_UST_EVENT_HT_SIZE; i++)
 155                 CDS_INIT_HLIST_HEAD(&session->events_ht.table[i]);
 156         for (i = 0; i < LTTNG_UST_ENUM_HT_SIZE; i++)
 157                 CDS_INIT_HLIST_HEAD(&session->enums_ht.table[i]);
 158         cds_list_add(&session->node, &sessions);
 159         return session;
 160 }
 161
 162 /*
 163  * Only used internally at session destruction.
 164  */
 165 static
 166 void _lttng_channel_unmap(struct lttng_channel *lttng_chan)
 167 {
 168         struct channel *chan;
 169         struct lttng_ust_shm_handle *handle;
 170
 171         cds_list_del(&lttng_chan->node);
 172         lttng_destroy_context(lttng_chan->ctx);
 173         chan = lttng_chan->chan;
 174         handle = lttng_chan->handle;
 175         /*
 176          * note: lttng_chan is private data contained within handle. It
 177          * will be freed along with the handle.
 178          */
 179         channel_destroy(chan, handle, 0);
 180 }
 181
 182 static
 183 void register_event(struct lttng_event *event)
 184 {
 185         int ret;
 186         const struct lttng_event_desc *desc;
 187
 188         assert(event->registered == 0);
 189         desc = event->desc;
 190         ret = __tracepoint_probe_register_queue_release(desc->name,
 191                         desc->probe_callback,
 192                         event, desc->signature);
 193         WARN_ON_ONCE(ret);
 194         if (!ret)
 195                 event->registered = 1;
 196 }
 197
 198 static
 199 void unregister_event(struct lttng_event *event)
 200 {
 201         int ret;
 202         const struct lttng_event_desc *desc;
 203
 204         assert(event->registered == 1);
 205         desc = event->desc;
 206         ret = __tracepoint_probe_unregister_queue_release(desc->name,
 207                         desc->probe_callback,
 208                         event);
 209         WARN_ON_ONCE(ret);
 210         if (!ret)
 211                 event->registered = 0;
 212 }
 213
 214 /*
 215  * Only used internally at session destruction.
 216  */
 217 static
 218 void _lttng_event_unregister(struct lttng_event *event)
 219 {
 220         if (event->registered)
 221                 unregister_event(event);
 222 }
 223
 224 void lttng_session_destroy(struct lttng_session *session)
 225 {
 226         struct lttng_channel *chan, *tmpchan;
 227         struct lttng_event *event, *tmpevent;
 228         struct lttng_enum *_enum, *tmp_enum;
 229         struct lttng_enabler *enabler, *tmpenabler;
 230
 231         CMM_ACCESS_ONCE(session->active) = 0;
 232         cds_list_for_each_entry(event, &session->events_head, node) {
 233                 _lttng_event_unregister(event);
 234         }
 235         synchronize_trace();    /* Wait for in-flight events to complete */
 236         __tracepoint_probe_prune_release_queue();
 237         cds_list_for_each_entry_safe(enabler, tmpenabler,
 238                         &session->enablers_head, node)
 239                 lttng_enabler_destroy(enabler);
 240         cds_list_for_each_entry_safe(event, tmpevent,
 241                         &session->events_head, node)
 242                 _lttng_event_destroy(event);
 243         cds_list_for_each_entry_safe(_enum, tmp_enum,
 244                         &session->enums_head, node)
 245                 _lttng_enum_destroy(_enum);
 246         cds_list_for_each_entry_safe(chan, tmpchan, &session->chan_head, node)
 247                 _lttng_channel_unmap(chan);
 248         cds_list_del(&session->node);
 249         lttng_destroy_context(session->ctx);
 250         free(session);
 251 }
 252
 253 static
 254 int lttng_enum_create(const struct lttng_enum_desc *desc,
 255                 struct lttng_session *session)
 256 {
 257         const char *enum_name = desc->name;
 258         struct lttng_enum *_enum;
 259         struct cds_hlist_head *head;
 260         int ret = 0;
 261         size_t name_len = strlen(enum_name);
 262         uint32_t hash;
 263         int notify_socket;
 264
 265         /* Check if this enum is already registered for this session. */
 266         hash = jhash(enum_name, name_len, 0);
 267         head = &session->enums_ht.table[hash & (LTTNG_UST_ENUM_HT_SIZE - 1)];
 268
 269         _enum = lttng_ust_enum_get_from_desc(session, desc);
 270         if (_enum) {
 271                 ret = -EEXIST;
 272                 goto exist;
 273         }
 274
 275         notify_socket = lttng_get_notify_socket(session->owner);
 276         if (notify_socket < 0) {
 277                 ret = notify_socket;
 278                 goto socket_error;
 279         }
 280
 281         _enum = zmalloc(sizeof(*_enum));
 282         if (!_enum) {
 283                 ret = -ENOMEM;
 284                 goto cache_error;
 285         }
 286         _enum->session = session;
 287         _enum->desc = desc;
 288
 289         ret = ustcomm_register_enum(notify_socket,
 290                 session->objd,
 291                 enum_name,
 292                 desc->nr_entries,
 293                 desc->entries,
 294                 &_enum->id);
 295         if (ret < 0) {
 296                 DBG("Error (%d) registering enumeration to sessiond", ret);
 297                 goto sessiond_register_error;
 298         }
 299         cds_list_add(&_enum->node, &session->enums_head);
 300         cds_hlist_add_head(&_enum->hlist, head);
 301         return 0;
 302
 303 sessiond_register_error:
 304         free(_enum);
 305 cache_error:
 306 socket_error:
 307 exist:
 308         return ret;
 309 }
 310
 311 static
 312 int lttng_create_enum_check(const struct lttng_type *type,
 313                 struct lttng_session *session)
 314 {
 315         switch (type->atype) {
 316         case atype_enum:
 317         {
 318                 const struct lttng_enum_desc *enum_desc;
 319                 int ret;
 320
 321                 enum_desc = type->u.basic.enumeration.desc;
 322                 ret = lttng_enum_create(enum_desc, session);
 323                 if (ret && ret != -EEXIST) {
 324                         DBG("Unable to create enum error: (%d)", ret);
 325                         return ret;
 326                 }
 327                 break;
 328         }
 329         case atype_dynamic:
 330         {
 331                 const struct lttng_event_field *tag_field_generic;
 332                 const struct lttng_enum_desc *enum_desc;
 333                 int ret;
 334
 335                 tag_field_generic = lttng_ust_dynamic_type_tag_field();
 336                 enum_desc = tag_field_generic->type.u.basic.enumeration.desc;
 337                 ret = lttng_enum_create(enum_desc, session);
 338                 if (ret && ret != -EEXIST) {
 339                         DBG("Unable to create enum error: (%d)", ret);
 340                         return ret;
 341                 }
 342                 break;
 343         }
 344         default:
 345                 /* TODO: nested types when they become supported. */
 346                 break;
 347         }
 348         return 0;
 349 }
 350
 351 static
 352 int lttng_create_all_event_enums(size_t nr_fields,
 353                 const struct lttng_event_field *event_fields,
 354                 struct lttng_session *session)
 355 {
 356         size_t i;
 357         int ret;
 358
 359         /* For each field, ensure enum is part of the session. */
 360         for (i = 0; i < nr_fields; i++) {
 361                 const struct lttng_type *type = &event_fields[i].type;
 362
 363                 ret = lttng_create_enum_check(type, session);
 364                 if (ret)
 365                         return ret;
 366         }
 367         return 0;
 368 }
 369
 370 static
 371 int lttng_create_all_ctx_enums(size_t nr_fields,
 372                 const struct lttng_ctx_field *ctx_fields,
 373                 struct lttng_session *session)
 374 {
 375         size_t i;
 376         int ret;
 377
 378         /* For each field, ensure enum is part of the session. */
 379         for (i = 0; i < nr_fields; i++) {
 380                 const struct lttng_type *type = &ctx_fields[i].event_field.type;
 381
 382                 ret = lttng_create_enum_check(type, session);
 383                 if (ret)
 384                         return ret;
 385         }
 386         return 0;
 387 }
 388
 389 /*
 390  * Ensure that a state-dump will be performed for this session at the end
 391  * of the current handle_message().
 392  */
 393 int lttng_session_statedump(struct lttng_session *session)
 394 {
 395         session->statedump_pending = 1;
 396         lttng_ust_sockinfo_session_enabled(session->owner);
 397         return 0;
 398 }
 399
 400 int lttng_session_enable(struct lttng_session *session)
 401 {
 402         int ret = 0;
 403         struct lttng_channel *chan;
 404         int notify_socket;
 405
 406         if (session->active) {
 407                 ret = -EBUSY;
 408                 goto end;
 409         }
 410
 411         notify_socket = lttng_get_notify_socket(session->owner);
 412         if (notify_socket < 0)
 413                 return notify_socket;
 414
 415         /* Set transient enabler state to "enabled" */
 416         session->tstate = 1;
 417
 418         /* We need to sync enablers with session before activation. */
 419         lttng_session_sync_enablers(session);
 420
 421         /*
 422          * Snapshot the number of events per channel to know the type of header
 423          * we need to use.
 424          */
 425         cds_list_for_each_entry(chan, &session->chan_head, node) {
 426                 const struct lttng_ctx *ctx;
 427                 const struct lttng_ctx_field *fields = NULL;
 428                 size_t nr_fields = 0;
 429                 uint32_t chan_id;
 430
 431                 /* don't change it if session stop/restart */
 432                 if (chan->header_type)
 433                         continue;
 434                 ctx = chan->ctx;
 435                 if (ctx) {
 436                         nr_fields = ctx->nr_fields;
 437                         fields = ctx->fields;
 438                         ret = lttng_create_all_ctx_enums(nr_fields, fields,
 439                                 session);
 440                         if (ret < 0) {
 441                                 DBG("Error (%d) adding enum to session", ret);
 442                                 return ret;
 443                         }
 444                 }
 445                 ret = ustcomm_register_channel(notify_socket,
 446                         session,
 447                         session->objd,
 448                         chan->objd,
 449                         nr_fields,
 450                         fields,
 451                         &chan_id,
 452                         &chan->header_type);
 453                 if (ret) {
 454                         DBG("Error (%d) registering channel to sessiond", ret);
 455                         return ret;
 456                 }
 457                 if (chan_id != chan->id) {
 458                         DBG("Error: channel registration id (%u) does not match id assigned at creation (%u)",
 459                                 chan_id, chan->id);
 460                         return -EINVAL;
 461                 }
 462         }
 463
 464         /* Set atomically the state to "active" */
 465         CMM_ACCESS_ONCE(session->active) = 1;
 466         CMM_ACCESS_ONCE(session->been_active) = 1;
 467
 468         ret = lttng_session_statedump(session);
 469         if (ret)
 470                 return ret;
 471 end:
 472         return ret;
 473 }
 474
 475 int lttng_session_disable(struct lttng_session *session)
 476 {
 477         int ret = 0;
 478
 479         if (!session->active) {
 480                 ret = -EBUSY;
 481                 goto end;
 482         }
 483         /* Set atomically the state to "inactive" */
 484         CMM_ACCESS_ONCE(session->active) = 0;
 485
 486         /* Set transient enabler state to "disabled" */
 487         session->tstate = 0;
 488         lttng_session_sync_enablers(session);
 489 end:
 490         return ret;
 491 }
 492
 493 int lttng_channel_enable(struct lttng_channel *channel)
 494 {
 495         int ret = 0;
 496
 497         if (channel->enabled) {
 498                 ret = -EBUSY;
 499                 goto end;
 500         }
 501         /* Set transient enabler state to "enabled" */
 502         channel->tstate = 1;
 503         lttng_session_sync_enablers(channel->session);
 504         /* Set atomically the state to "enabled" */
 505         CMM_ACCESS_ONCE(channel->enabled) = 1;
 506 end:
 507         return ret;
 508 }
 509
 510 int lttng_channel_disable(struct lttng_channel *channel)
 511 {
 512         int ret = 0;
 513
 514         if (!channel->enabled) {
 515                 ret = -EBUSY;
 516                 goto end;
 517         }
 518         /* Set atomically the state to "disabled" */
 519         CMM_ACCESS_ONCE(channel->enabled) = 0;
 520         /* Set transient enabler state to "enabled" */
 521         channel->tstate = 0;
 522         lttng_session_sync_enablers(channel->session);
 523 end:
 524         return ret;
 525 }
 526
 527 /*
 528  * Supports event creation while tracing session is active.
 529  */
 530 static
 531 int lttng_event_create(const struct lttng_event_desc *desc,
 532                 struct lttng_channel *chan)
 533 {
 534         const char *event_name = desc->name;
 535         struct lttng_event *event;
 536         struct lttng_session *session = chan->session;
 537         struct cds_hlist_head *head;
 538         int ret = 0;
 539         size_t name_len = strlen(event_name);
 540         uint32_t hash;
 541         int notify_socket, loglevel;
 542         const char *uri;
 543
 544         hash = jhash(event_name, name_len, 0);
 545         head = &chan->session->events_ht.table[hash & (LTTNG_UST_EVENT_HT_SIZE - 1)];
 546
 547         notify_socket = lttng_get_notify_socket(session->owner);
 548         if (notify_socket < 0) {
 549                 ret = notify_socket;
 550                 goto socket_error;
 551         }
 552
 553         ret = lttng_create_all_event_enums(desc->nr_fields, desc->fields,
 554                         session);
 555         if (ret < 0) {
 556                 DBG("Error (%d) adding enum to session", ret);
 557                 goto create_enum_error;
 558         }
 559
 560         /*
 561          * Check if loglevel match. Refuse to connect event if not.
 562          */
 563         event = zmalloc(sizeof(struct lttng_event));
 564         if (!event) {
 565                 ret = -ENOMEM;
 566                 goto cache_error;
 567         }
 568         event->chan = chan;
 569
 570         /* Event will be enabled by enabler sync. */
 571         event->enabled = 0;
 572         event->registered = 0;
 573         CDS_INIT_LIST_HEAD(&event->bytecode_runtime_head);
 574         CDS_INIT_LIST_HEAD(&event->enablers_ref_head);
 575         event->desc = desc;
 576
 577         if (desc->loglevel)
 578                 loglevel = *(*event->desc->loglevel);
 579         else
 580                 loglevel = TRACE_DEFAULT;
 581         if (desc->u.ext.model_emf_uri)
 582                 uri = *(desc->u.ext.model_emf_uri);
 583         else
 584                 uri = NULL;
 585
 586         /* Fetch event ID from sessiond */
 587         ret = ustcomm_register_event(notify_socket,
 588                 session,
 589                 session->objd,
 590                 chan->objd,
 591                 event_name,
 592                 loglevel,
 593                 desc->signature,
 594                 desc->nr_fields,
 595                 desc->fields,
 596                 uri,
 597                 &event->id);
 598         if (ret < 0) {
 599                 DBG("Error (%d) registering event to sessiond", ret);
 600                 goto sessiond_register_error;
 601         }
 602
 603         cds_list_add(&event->node, &chan->session->events_head);
 604         cds_hlist_add_head(&event->hlist, head);
 605         return 0;
 606
 607 sessiond_register_error:
 608         free(event);
 609 cache_error:
 610 create_enum_error:
 611 socket_error:
 612         return ret;
 613 }
 614
 615 static
 616 int lttng_desc_match_star_glob_enabler(const struct lttng_event_desc *desc,
 617                 struct lttng_enabler *enabler)
 618 {
 619         int loglevel = 0;
 620         unsigned int has_loglevel = 0;
 621
 622         assert(enabler->type == LTTNG_ENABLER_STAR_GLOB);
 623         if (!strutils_star_glob_match(enabler->event_param.name, SIZE_MAX,
 624                         desc->name, SIZE_MAX))
 625                 return 0;
 626         if (desc->loglevel) {
 627                 loglevel = *(*desc->loglevel);
 628                 has_loglevel = 1;
 629         }
 630         if (!lttng_loglevel_match(loglevel,
 631                         has_loglevel,
 632                         enabler->event_param.loglevel_type,
 633                         enabler->event_param.loglevel))
 634                 return 0;
 635         return 1;
 636 }
 637
 638 static
 639 int lttng_desc_match_event_enabler(const struct lttng_event_desc *desc,
 640                 struct lttng_enabler *enabler)
 641 {
 642         int loglevel = 0;
 643         unsigned int has_loglevel = 0;
 644
 645         assert(enabler->type == LTTNG_ENABLER_EVENT);
 646         if (strcmp(desc->name, enabler->event_param.name))
 647                 return 0;
 648         if (desc->loglevel) {
 649                 loglevel = *(*desc->loglevel);
 650                 has_loglevel = 1;
 651         }
 652         if (!lttng_loglevel_match(loglevel,
 653                         has_loglevel,
 654                         enabler->event_param.loglevel_type,
 655                         enabler->event_param.loglevel))
 656                 return 0;
 657         return 1;
 658 }
 659
 660 static
 661 int lttng_desc_match_enabler(const struct lttng_event_desc *desc,
 662                 struct lttng_enabler *enabler)
 663 {
 664         switch (enabler->type) {
 665         case LTTNG_ENABLER_STAR_GLOB:
 666         {
 667                 struct lttng_ust_excluder_node *excluder;
 668
 669                 if (!lttng_desc_match_star_glob_enabler(desc, enabler)) {
 670                         return 0;
 671                 }
 672
 673                 /*
 674                  * If the matching event matches with an excluder,
 675                  * return 'does not match'
 676                  */
 677                 cds_list_for_each_entry(excluder, &enabler->excluder_head, node) {
 678                         int count;
 679
 680                         for (count = 0; count < excluder->excluder.count; count++) {
 681                                 int len;
 682                                 char *excluder_name;
 683
 684                                 excluder_name = (char *) (excluder->excluder.names)
 685                                                 + count * LTTNG_UST_SYM_NAME_LEN;
 686                                 len = strnlen(excluder_name, LTTNG_UST_SYM_NAME_LEN);
 687                                 if (len > 0 && strutils_star_glob_match(excluder_name, len, desc->name, SIZE_MAX))
 688                                         return 0;
 689                         }
 690                 }
 691                 return 1;
 692         }
 693         case LTTNG_ENABLER_EVENT:
 694                 return lttng_desc_match_event_enabler(desc, enabler);
 695         default:
 696                 return -EINVAL;
 697         }
 698 }
 699
 700 static
 701 int lttng_event_match_enabler(struct lttng_event *event,
 702                 struct lttng_enabler *enabler)
 703 {
 704         if (lttng_desc_match_enabler(event->desc, enabler)
 705                         && event->chan == enabler->chan)
 706                 return 1;
 707         else
 708                 return 0;
 709 }
 710
 711 static
 712 struct lttng_enabler_ref * lttng_event_enabler_ref(struct lttng_event *event,
 713                 struct lttng_enabler *enabler)
 714 {
 715         struct lttng_enabler_ref *enabler_ref;
 716
 717         cds_list_for_each_entry(enabler_ref,
 718                         &event->enablers_ref_head, node) {
 719                 if (enabler_ref->ref == enabler)
 720                         return enabler_ref;
 721         }
 722         return NULL;
 723 }
 724
 725 /*
 726  * Create struct lttng_event if it is missing and present in the list of
 727  * tracepoint probes.
 728  */
 729 static
 730 void lttng_create_event_if_missing(struct lttng_enabler *enabler)
 731 {
 732         struct lttng_session *session = enabler->chan->session;
 733         struct lttng_probe_desc *probe_desc;
 734         const struct lttng_event_desc *desc;
 735         struct lttng_event *event;
 736         int i;
 737         struct cds_list_head *probe_list;
 738
 739         probe_list = lttng_get_probe_list_head();
 740         /*
 741          * For each probe event, if we find that a probe event matches
 742          * our enabler, create an associated lttng_event if not
 743          * already present.
 744          */
 745         cds_list_for_each_entry(probe_desc, probe_list, head) {
 746                 for (i = 0; i < probe_desc->nr_events; i++) {
 747                         int ret;
 748                         bool found = false;
 749                         struct cds_hlist_head *head;
 750                         struct cds_hlist_node *node;
 751                         const char *event_name;
 752                         size_t name_len;
 753                         uint32_t hash;
 754
 755                         desc = probe_desc->event_desc[i];
 756                         if (!lttng_desc_match_enabler(desc, enabler))
 757                                 continue;
 758                         event_name = desc->name;
 759                         name_len = strlen(event_name);
 760
 761                         /*
 762                          * Check if already created.
 763                          */
 764                         hash = jhash(event_name, name_len, 0);
 765                         head = &session->events_ht.table[hash & (LTTNG_UST_EVENT_HT_SIZE - 1)];
 766                         cds_hlist_for_each_entry(event, node, head, hlist) {
 767                                 if (event->desc == desc
 768                                                 && event->chan == enabler->chan) {
 769                                         found = true;
 770                                         break;
 771                                 }
 772                         }
 773                         if (found)
 774                                 continue;
 775
 776                         /*
 777                          * We need to create an event for this
 778                          * event probe.
 779                          */
 780                         ret = lttng_event_create(probe_desc->event_desc[i],
 781                                         enabler->chan);
 782                         if (ret) {
 783                                 DBG("Unable to create event %s, error %d\n",
 784                                         probe_desc->event_desc[i]->name, ret);
 785                         }
 786                 }
 787         }
 788 }
 789
 790 /*
 791  * Iterate over all the UST sessions to unregister and destroy all probes from
 792  * the probe provider descriptor received as argument. Must me called with the
 793  * ust_lock held.
 794  */
 795 void lttng_probe_provider_unregister_events(struct lttng_probe_desc *provider_desc)
 796 {
 797         struct cds_hlist_node *node, *tmp_node;
 798         struct cds_list_head *sessionsp;
 799         struct lttng_session *session;
 800         struct cds_hlist_head *head;
 801         struct lttng_event *event;
 802         unsigned int i, j;
 803
 804         /* Get handle on list of sessions. */
 805         sessionsp = _lttng_get_sessions();
 806
 807         /*
 808          * Iterate over all events in the probe provider descriptions and sessions
 809          * to queue the unregistration of the events.
 810          */
 811         for (i = 0; i < provider_desc->nr_events; i++) {
 812                 const struct lttng_event_desc *event_desc;
 813                 const char *event_name;
 814                 size_t name_len;
 815                 uint32_t hash;
 816
 817                 event_desc = provider_desc->event_desc[i];
 818                 event_name = event_desc->name;
 819                 name_len = strlen(event_name);
 820                 hash = jhash(event_name, name_len, 0);
 821
 822                 /* Iterate over all session to find the current event description. */
 823                 cds_list_for_each_entry(session, sessionsp, node) {
 824                         /*
 825                          * Get the list of events in the hashtable bucket and iterate to
 826                          * find the event matching this descriptor.
 827                          */
 828                         head = &session->events_ht.table[hash & (LTTNG_UST_EVENT_HT_SIZE - 1)];
 829                         cds_hlist_for_each_entry(event, node, head, hlist) {
 830                                 if (event_desc == event->desc) {
 831                                         /* Queue the unregistration of this event. */
 832                                         _lttng_event_unregister(event);
 833                                         break;
 834                                 }
 835                         }
 836                 }
 837         }
 838
 839         /* Wait for grace period. */
 840         synchronize_trace();
 841         /* Prune the unregistration queue. */
 842         __tracepoint_probe_prune_release_queue();
 843
 844         /*
 845          * It is now safe to destroy the events and remove them from the event list
 846          * and hashtables.
 847          */
 848         for (i = 0; i < provider_desc->nr_events; i++) {
 849                 const struct lttng_event_desc *event_desc;
 850                 const char *event_name;
 851                 size_t name_len;
 852                 uint32_t hash;
 853
 854                 event_desc = provider_desc->event_desc[i];
 855                 event_name = event_desc->name;
 856                 name_len = strlen(event_name);
 857                 hash = jhash(event_name, name_len, 0);
 858
 859                 /* Iterate over all sessions to find the current event description. */
 860                 cds_list_for_each_entry(session, sessionsp, node) {
 861                         /*
 862                          * Get the list of events in the hashtable bucket and iterate to
 863                          * find the event matching this descriptor.
 864                          */
 865                         head = &session->events_ht.table[hash & (LTTNG_UST_EVENT_HT_SIZE - 1)];
 866                         cds_hlist_for_each_entry_safe(event, node, tmp_node, head, hlist) {
 867                                 if (event_desc == event->desc) {
 868                                         /* Destroy enums of the current event. */
 869                                         for (j = 0; j < event->desc->nr_fields; j++) {
 870                                                 const struct lttng_enum_desc *enum_desc;
 871                                                 const struct lttng_event_field *field;
 872                                                 struct lttng_enum *curr_enum;
 873
 874                                                 field = &(event->desc->fields[j]);
 875                                                 if (field->type.atype != atype_enum) {
 876                                                         continue;
 877                                                 }
 878
 879                                                 enum_desc = field->type.u.basic.enumeration.desc;
 880                                                 curr_enum = lttng_ust_enum_get_from_desc(session, enum_desc);
 881                                                 if (curr_enum) {
 882                                                         _lttng_enum_destroy(curr_enum);
 883                                                 }
 884                                         }
 885
 886                                         /* Destroy event. */
 887                                         _lttng_event_destroy(event);
 888                                         break;
 889                                 }
 890                         }
 891                 }
 892         }
 893 }
 894
 895 /*
 896  * Create events associated with an enabler (if not already present),
 897  * and add backward reference from the event to the enabler.
 898  */
 899 static
 900 int lttng_enabler_ref_events(struct lttng_enabler *enabler)
 901 {
 902         struct lttng_session *session = enabler->chan->session;
 903         struct lttng_event *event;
 904
 905         /* First ensure that probe events are created for this enabler. */
 906         lttng_create_event_if_missing(enabler);
 907
 908         /* For each event matching enabler in session event list. */
 909         cds_list_for_each_entry(event, &session->events_head, node) {
 910                 struct lttng_enabler_ref *enabler_ref;
 911
 912                 if (!lttng_event_match_enabler(event, enabler))
 913                         continue;
 914
 915                 enabler_ref = lttng_event_enabler_ref(event, enabler);
 916                 if (!enabler_ref) {
 917                         /*
 918                          * If no backward ref, create it.
 919                          * Add backward ref from event to enabler.
 920                          */
 921                         enabler_ref = zmalloc(sizeof(*enabler_ref));
 922                         if (!enabler_ref)
 923                                 return -ENOMEM;
 924                         enabler_ref->ref = enabler;
 925                         cds_list_add(&enabler_ref->node,
 926                                 &event->enablers_ref_head);
 927                 }
 928
 929                 /*
 930                  * Link filter bytecodes if not linked yet.
 931                  */
 932                 lttng_enabler_event_link_bytecode(event, enabler);
 933
 934                 /* TODO: merge event context. */
 935         }
 936         return 0;
 937 }
 938
 939 /*
 940  * Called at library load: connect the probe on all enablers matching
 941  * this event.
 942  * Called with session mutex held.
 943  */
 944 int lttng_fix_pending_events(void)
 945 {
 946         struct lttng_session *session;
 947
 948         cds_list_for_each_entry(session, &sessions, node) {
 949                 lttng_session_lazy_sync_enablers(session);
 950         }
 951         return 0;
 952 }
 953
 954 /*
 955  * For each session of the owner thread, execute pending statedump.
 956  * Only dump state for the sessions owned by the caller thread, because
 957  * we don't keep ust_lock across the entire iteration.
 958  */
 959 void lttng_handle_pending_statedump(void *owner)
 960 {
 961         struct lttng_session *session;
 962
 963         /* Execute state dump */
 964         do_lttng_ust_statedump(owner);
 965
 966         /* Clear pending state dump */
 967         if (ust_lock()) {
 968                 goto end;
 969         }
 970         cds_list_for_each_entry(session, &sessions, node) {
 971                 if (session->owner != owner)
 972                         continue;
 973                 if (!session->statedump_pending)
 974                         continue;
 975                 session->statedump_pending = 0;
 976         }
 977 end:
 978         ust_unlock();
 979         return;
 980 }
 981
 982 /*
 983  * Only used internally at session destruction.
 984  */
 985 static
 986 void _lttng_event_destroy(struct lttng_event *event)
 987 {
 988         struct lttng_enabler_ref *enabler_ref, *tmp_enabler_ref;
 989
 990         /* Remove from event list. */
 991         cds_list_del(&event->node);
 992         /* Remove from event hash table. */
 993         cds_hlist_del(&event->hlist);
 994
 995         lttng_destroy_context(event->ctx);
 996         lttng_free_event_filter_runtime(event);
 997         /* Free event enabler refs */
 998         cds_list_for_each_entry_safe(enabler_ref, tmp_enabler_ref,
 999                         &event->enablers_ref_head, node)
1000                 free(enabler_ref);
1001         free(event);
1002 }
1003
1004 static
1005 void _lttng_enum_destroy(struct lttng_enum *_enum)
1006 {
1007         cds_list_del(&_enum->node);
1008         cds_hlist_del(&_enum->hlist);
1009         free(_enum);
1010 }
1011
1012 void lttng_ust_events_exit(void)
1013 {
1014         struct lttng_session *session, *tmpsession;
1015
1016         cds_list_for_each_entry_safe(session, tmpsession, &sessions, node)
1017                 lttng_session_destroy(session);
1018 }
1019
1020 /*
1021  * Enabler management.
1022  */
1023 struct lttng_enabler *lttng_enabler_create(enum lttng_enabler_type type,
1024                 struct lttng_ust_event *event_param,
1025                 struct lttng_channel *chan)
1026 {
1027         struct lttng_enabler *enabler;
1028
1029         enabler = zmalloc(sizeof(*enabler));
1030         if (!enabler)
1031                 return NULL;
1032         enabler->type = type;
1033         CDS_INIT_LIST_HEAD(&enabler->filter_bytecode_head);
1034         CDS_INIT_LIST_HEAD(&enabler->excluder_head);
1035         memcpy(&enabler->event_param, event_param,
1036                 sizeof(enabler->event_param));
1037         enabler->chan = chan;
1038         /* ctx left NULL */
1039         enabler->enabled = 0;
1040         cds_list_add(&enabler->node, &enabler->chan->session->enablers_head);
1041         lttng_session_lazy_sync_enablers(enabler->chan->session);
1042         return enabler;
1043 }
1044
1045 int lttng_enabler_enable(struct lttng_enabler *enabler)
1046 {
1047         enabler->enabled = 1;
1048         lttng_session_lazy_sync_enablers(enabler->chan->session);
1049         return 0;
1050 }
1051
1052 int lttng_enabler_disable(struct lttng_enabler *enabler)
1053 {
1054         enabler->enabled = 0;
1055         lttng_session_lazy_sync_enablers(enabler->chan->session);
1056         return 0;
1057 }
1058
1059 int lttng_enabler_attach_bytecode(struct lttng_enabler *enabler,
1060                 struct lttng_ust_filter_bytecode_node *bytecode)
1061 {
1062         bytecode->enabler = enabler;
1063         cds_list_add_tail(&bytecode->node, &enabler->filter_bytecode_head);
1064         lttng_session_lazy_sync_enablers(enabler->chan->session);
1065         return 0;
1066 }
1067
1068 int lttng_enabler_attach_exclusion(struct lttng_enabler *enabler,
1069                 struct lttng_ust_excluder_node *excluder)
1070 {
1071         excluder->enabler = enabler;
1072         cds_list_add_tail(&excluder->node, &enabler->excluder_head);
1073         lttng_session_lazy_sync_enablers(enabler->chan->session);
1074         return 0;
1075 }
1076
1077 int lttng_attach_context(struct lttng_ust_context *context_param,
1078                 union ust_args *uargs,
1079                 struct lttng_ctx **ctx, struct lttng_session *session)
1080 {
1081         /*
1082          * We cannot attach a context after trace has been started for a
1083          * session because the metadata does not allow expressing this
1084          * information outside of the original channel scope.
1085          */
1086         if (session->been_active)
1087                 return -EPERM;
1088
1089         switch (context_param->ctx) {
1090         case LTTNG_UST_CONTEXT_PTHREAD_ID:
1091                 return lttng_add_pthread_id_to_ctx(ctx);
1092         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
1093         {
1094                 struct lttng_ust_perf_counter_ctx *perf_ctx_param;
1095
1096                 perf_ctx_param = &context_param->u.perf_counter;
1097                 return lttng_add_perf_counter_to_ctx(
1098                         perf_ctx_param->type,
1099                         perf_ctx_param->config,
1100                         perf_ctx_param->name,
1101                         ctx);
1102         }
1103         case LTTNG_UST_CONTEXT_VTID:
1104                 return lttng_add_vtid_to_ctx(ctx);
1105         case LTTNG_UST_CONTEXT_VPID:
1106                 return lttng_add_vpid_to_ctx(ctx);
1107         case LTTNG_UST_CONTEXT_PROCNAME:
1108                 return lttng_add_procname_to_ctx(ctx);
1109         case LTTNG_UST_CONTEXT_IP:
1110                 return lttng_add_ip_to_ctx(ctx);
1111         case LTTNG_UST_CONTEXT_CPU_ID:
1112                 return lttng_add_cpu_id_to_ctx(ctx);
1113         case LTTNG_UST_CONTEXT_APP_CONTEXT:
1114                 return lttng_ust_add_app_context_to_ctx_rcu(uargs->app_context.ctxname,
1115                         ctx);
1116         case LTTNG_UST_CONTEXT_CGROUP_NS:
1117                 return lttng_add_cgroup_ns_to_ctx(ctx);
1118         case LTTNG_UST_CONTEXT_IPC_NS:
1119                 return lttng_add_ipc_ns_to_ctx(ctx);
1120         case LTTNG_UST_CONTEXT_MNT_NS:
1121                 return lttng_add_mnt_ns_to_ctx(ctx);
1122         case LTTNG_UST_CONTEXT_NET_NS:
1123                 return lttng_add_net_ns_to_ctx(ctx);
1124         case LTTNG_UST_CONTEXT_PID_NS:
1125                 return lttng_add_pid_ns_to_ctx(ctx);
1126         case LTTNG_UST_CONTEXT_USER_NS:
1127                 return lttng_add_user_ns_to_ctx(ctx);
1128         case LTTNG_UST_CONTEXT_UTS_NS:
1129                 return lttng_add_uts_ns_to_ctx(ctx);
1130         case LTTNG_UST_CONTEXT_VUID:
1131                 return lttng_add_vuid_to_ctx(ctx);
1132         case LTTNG_UST_CONTEXT_VEUID:
1133                 return lttng_add_veuid_to_ctx(ctx);
1134         case LTTNG_UST_CONTEXT_VSUID:
1135                 return lttng_add_vsuid_to_ctx(ctx);
1136         case LTTNG_UST_CONTEXT_VGID:
1137                 return lttng_add_vgid_to_ctx(ctx);
1138         case LTTNG_UST_CONTEXT_VEGID:
1139                 return lttng_add_vegid_to_ctx(ctx);
1140         case LTTNG_UST_CONTEXT_VSGID:
1141                 return lttng_add_vsgid_to_ctx(ctx);
1142         default:
1143                 return -EINVAL;
1144         }
1145 }
1146
1147 int lttng_enabler_attach_context(struct lttng_enabler *enabler,
1148                 struct lttng_ust_context *context_param)
1149 {
1150 #if 0   // disabled for now.
1151         struct lttng_session *session = enabler->chan->session;
1152         int ret;
1153
1154         ret = lttng_attach_context(context_param, &enabler->ctx,
1155                         session);
1156         if (ret)
1157                 return ret;
1158         lttng_session_lazy_sync_enablers(enabler->chan->session);
1159 #endif
1160         return -ENOSYS;
1161 }
1162
1163 static
1164 void lttng_enabler_destroy(struct lttng_enabler *enabler)
1165 {
1166         struct lttng_ust_filter_bytecode_node *filter_node, *tmp_filter_node;
1167         struct lttng_ust_excluder_node *excluder_node, *tmp_excluder_node;
1168
1169         /* Destroy filter bytecode */
1170         cds_list_for_each_entry_safe(filter_node, tmp_filter_node,
1171                         &enabler->filter_bytecode_head, node) {
1172                 free(filter_node);
1173         }
1174
1175         /* Destroy excluders */
1176         cds_list_for_each_entry_safe(excluder_node, tmp_excluder_node,
1177                         &enabler->excluder_head, node) {
1178                 free(excluder_node);
1179         }
1180
1181         /* Destroy contexts */
1182         lttng_destroy_context(enabler->ctx);
1183
1184         cds_list_del(&enabler->node);
1185         free(enabler);
1186 }
1187
1188 /*
1189  * lttng_session_sync_enablers should be called just before starting a
1190  * session.
1191  */
1192 static
1193 void lttng_session_sync_enablers(struct lttng_session *session)
1194 {
1195         struct lttng_enabler *enabler;
1196         struct lttng_event *event;
1197
1198         cds_list_for_each_entry(enabler, &session->enablers_head, node)
1199                 lttng_enabler_ref_events(enabler);
1200         /*
1201          * For each event, if at least one of its enablers is enabled,
1202          * and its channel and session transient states are enabled, we
1203          * enable the event, else we disable it.
1204          */
1205         cds_list_for_each_entry(event, &session->events_head, node) {
1206                 struct lttng_enabler_ref *enabler_ref;
1207                 struct lttng_bytecode_runtime *runtime;
1208                 int enabled = 0, has_enablers_without_bytecode = 0;
1209
1210                 /* Enable events */
1211                 cds_list_for_each_entry(enabler_ref,
1212                                 &event->enablers_ref_head, node) {
1213                         if (enabler_ref->ref->enabled) {
1214                                 enabled = 1;
1215                                 break;
1216                         }
1217                 }
1218                 /*
1219                  * Enabled state is based on union of enablers, with
1220                  * intesection of session and channel transient enable
1221                  * states.
1222                  */
1223                 enabled = enabled && session->tstate && event->chan->tstate;
1224
1225                 CMM_STORE_SHARED(event->enabled, enabled);
1226                 /*
1227                  * Sync tracepoint registration with event enabled
1228                  * state.
1229                  */
1230                 if (enabled) {
1231                         if (!event->registered)
1232                                 register_event(event);
1233                 } else {
1234                         if (event->registered)
1235                                 unregister_event(event);
1236                 }
1237
1238                 /* Check if has enablers without bytecode enabled */
1239                 cds_list_for_each_entry(enabler_ref,
1240                                 &event->enablers_ref_head, node) {
1241                         if (enabler_ref->ref->enabled
1242                                         && cds_list_empty(&enabler_ref->ref->filter_bytecode_head)) {
1243                                 has_enablers_without_bytecode = 1;
1244                                 break;
1245                         }
1246                 }
1247                 event->has_enablers_without_bytecode =
1248                         has_enablers_without_bytecode;
1249
1250                 /* Enable filters */
1251                 cds_list_for_each_entry(runtime,
1252                                 &event->bytecode_runtime_head, node) {
1253                         lttng_filter_sync_state(runtime);
1254                 }
1255         }
1256         __tracepoint_probe_prune_release_queue();
1257 }
1258
1259 /*
1260  * Apply enablers to session events, adding events to session if need
1261  * be. It is required after each modification applied to an active
1262  * session, and right before session "start".
1263  * "lazy" sync means we only sync if required.
1264  */
1265 static
1266 void lttng_session_lazy_sync_enablers(struct lttng_session *session)
1267 {
1268         /* We can skip if session is not active */
1269         if (!session->active)
1270                 return;
1271         lttng_session_sync_enablers(session);
1272 }
1273
1274 /*
1275  * Update all sessions with the given app context.
1276  * Called with ust lock held.
1277  * This is invoked when an application context gets loaded/unloaded. It
1278  * ensures the context callbacks are in sync with the application
1279  * context (either app context callbacks, or dummy callbacks).
1280  */
1281 void lttng_ust_context_set_session_provider(const char *name,
1282                 size_t (*get_size)(struct lttng_ctx_field *field, size_t offset),
1283                 void (*record)(struct lttng_ctx_field *field,
1284                         struct lttng_ust_lib_ring_buffer_ctx *ctx,
1285                         struct lttng_channel *chan),
1286                 void (*get_value)(struct lttng_ctx_field *field,
1287                         struct lttng_ctx_value *value))
1288 {
1289         struct lttng_session *session;
1290
1291         cds_list_for_each_entry(session, &sessions, node) {
1292                 struct lttng_channel *chan;
1293                 struct lttng_event *event;
1294                 int ret;
1295
1296                 ret = lttng_ust_context_set_provider_rcu(&session->ctx,
1297                                 name, get_size, record, get_value);
1298                 if (ret)
1299                         abort();
1300                 cds_list_for_each_entry(chan, &session->chan_head, node) {
1301                         ret = lttng_ust_context_set_provider_rcu(&chan->ctx,
1302                                         name, get_size, record, get_value);
1303                         if (ret)
1304                                 abort();
1305                 }
1306                 cds_list_for_each_entry(event, &session->events_head, node) {
1307                         ret = lttng_ust_context_set_provider_rcu(&event->ctx,
1308                                         name, get_size, record, get_value);
1309                         if (ret)
1310                                 abort();
1311                 }
1312         }
1313 }