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         struct cds_hlist_node *node;
 261         int ret = 0;
 262         size_t name_len = strlen(enum_name);
 263         uint32_t hash;
 264         int notify_socket;
 265
 266         hash = jhash(enum_name, name_len, 0);
 267         head = &session->enums_ht.table[hash & (LTTNG_UST_ENUM_HT_SIZE - 1)];
 268         cds_hlist_for_each_entry(_enum, node, head, hlist) {
 269                 assert(_enum->desc);
 270                 if (!strncmp(_enum->desc->name, desc->name,
 271                                 LTTNG_UST_SYM_NAME_LEN - 1)) {
 272                         ret = -EEXIST;
 273                         goto exist;
 274                 }
 275         }
 276
 277         notify_socket = lttng_get_notify_socket(session->owner);
 278         if (notify_socket < 0) {
 279                 ret = notify_socket;
 280                 goto socket_error;
 281         }
 282
 283         _enum = zmalloc(sizeof(*_enum));
 284         if (!_enum) {
 285                 ret = -ENOMEM;
 286                 goto cache_error;
 287         }
 288         _enum->session = session;
 289         _enum->desc = desc;
 290
 291         ret = ustcomm_register_enum(notify_socket,
 292                 session->objd,
 293                 enum_name,
 294                 desc->nr_entries,
 295                 desc->entries,
 296                 &_enum->id);
 297         if (ret < 0) {
 298                 DBG("Error (%d) registering enumeration to sessiond", ret);
 299                 goto sessiond_register_error;
 300         }
 301         cds_list_add(&_enum->node, &session->enums_head);
 302         cds_hlist_add_head(&_enum->hlist, head);
 303         return 0;
 304
 305 sessiond_register_error:
 306         free(_enum);
 307 cache_error:
 308 socket_error:
 309 exist:
 310         return ret;
 311 }
 312
 313 static
 314 int lttng_create_enum_check(const struct lttng_type *type,
 315                 struct lttng_session *session)
 316 {
 317         switch (type->atype) {
 318         case atype_enum:
 319         {
 320                 const struct lttng_enum_desc *enum_desc;
 321                 int ret;
 322
 323                 enum_desc = type->u.basic.enumeration.desc;
 324                 ret = lttng_enum_create(enum_desc, session);
 325                 if (ret && ret != -EEXIST) {
 326                         DBG("Unable to create enum error: (%d)", ret);
 327                         return ret;
 328                 }
 329                 break;
 330         }
 331         case atype_dynamic:
 332         {
 333                 const struct lttng_event_field *tag_field_generic;
 334                 const struct lttng_enum_desc *enum_desc;
 335                 int ret;
 336
 337                 tag_field_generic = lttng_ust_dynamic_type_tag_field();
 338                 enum_desc = tag_field_generic->type.u.basic.enumeration.desc;
 339                 ret = lttng_enum_create(enum_desc, session);
 340                 if (ret && ret != -EEXIST) {
 341                         DBG("Unable to create enum error: (%d)", ret);
 342                         return ret;
 343                 }
 344                 break;
 345         }
 346         default:
 347                 /* TODO: nested types when they become supported. */
 348                 break;
 349         }
 350         return 0;
 351 }
 352
 353 static
 354 int lttng_create_all_event_enums(size_t nr_fields,
 355                 const struct lttng_event_field *event_fields,
 356                 struct lttng_session *session)
 357 {
 358         size_t i;
 359         int ret;
 360
 361         /* For each field, ensure enum is part of the session. */
 362         for (i = 0; i < nr_fields; i++) {
 363                 const struct lttng_type *type = &event_fields[i].type;
 364
 365                 ret = lttng_create_enum_check(type, session);
 366                 if (ret)
 367                         return ret;
 368         }
 369         return 0;
 370 }
 371
 372 static
 373 int lttng_create_all_ctx_enums(size_t nr_fields,
 374                 const struct lttng_ctx_field *ctx_fields,
 375                 struct lttng_session *session)
 376 {
 377         size_t i;
 378         int ret;
 379
 380         /* For each field, ensure enum is part of the session. */
 381         for (i = 0; i < nr_fields; i++) {
 382                 const struct lttng_type *type = &ctx_fields[i].event_field.type;
 383
 384                 ret = lttng_create_enum_check(type, session);
 385                 if (ret)
 386                         return ret;
 387         }
 388         return 0;
 389 }
 390
 391 /*
 392  * Ensure that a state-dump will be performed for this session at the end
 393  * of the current handle_message().
 394  */
 395 int lttng_session_statedump(struct lttng_session *session)
 396 {
 397         session->statedump_pending = 1;
 398         lttng_ust_sockinfo_session_enabled(session->owner);
 399         return 0;
 400 }
 401
 402 int lttng_session_enable(struct lttng_session *session)
 403 {
 404         int ret = 0;
 405         struct lttng_channel *chan;
 406         int notify_socket;
 407
 408         if (session->active) {
 409                 ret = -EBUSY;
 410                 goto end;
 411         }
 412
 413         notify_socket = lttng_get_notify_socket(session->owner);
 414         if (notify_socket < 0)
 415                 return notify_socket;
 416
 417         /* Set transient enabler state to "enabled" */
 418         session->tstate = 1;
 419
 420         /*
 421          * Snapshot the number of events per channel to know the type of header
 422          * we need to use.
 423          */
 424         cds_list_for_each_entry(chan, &session->chan_head, node) {
 425                 const struct lttng_ctx *ctx;
 426                 const struct lttng_ctx_field *fields = NULL;
 427                 size_t nr_fields = 0;
 428                 uint32_t chan_id;
 429
 430                 /* don't change it if session stop/restart */
 431                 if (chan->header_type)
 432                         continue;
 433                 ctx = chan->ctx;
 434                 if (ctx) {
 435                         nr_fields = ctx->nr_fields;
 436                         fields = ctx->fields;
 437                         ret = lttng_create_all_ctx_enums(nr_fields, fields,
 438                                 session);
 439                         if (ret < 0) {
 440                                 DBG("Error (%d) adding enum to session", ret);
 441                                 return ret;
 442                         }
 443                 }
 444                 ret = ustcomm_register_channel(notify_socket,
 445                         session,
 446                         session->objd,
 447                         chan->objd,
 448                         nr_fields,
 449                         fields,
 450                         &chan_id,
 451                         &chan->header_type);
 452                 if (ret) {
 453                         DBG("Error (%d) registering channel to sessiond", ret);
 454                         return ret;
 455                 }
 456                 if (chan_id != chan->id) {
 457                         DBG("Error: channel registration id (%u) does not match id assigned at creation (%u)",
 458                                 chan_id, chan->id);
 459                         return -EINVAL;
 460                 }
 461         }
 462
 463         /* We need to sync enablers with session before activation. */
 464         lttng_session_sync_enablers(session);
 465
 466         /* Set atomically the state to "active" */
 467         CMM_ACCESS_ONCE(session->active) = 1;
 468         CMM_ACCESS_ONCE(session->been_active) = 1;
 469
 470         ret = lttng_session_statedump(session);
 471         if (ret)
 472                 return ret;
 473 end:
 474         return ret;
 475 }
 476
 477 int lttng_session_disable(struct lttng_session *session)
 478 {
 479         int ret = 0;
 480
 481         if (!session->active) {
 482                 ret = -EBUSY;
 483                 goto end;
 484         }
 485         /* Set atomically the state to "inactive" */
 486         CMM_ACCESS_ONCE(session->active) = 0;
 487
 488         /* Set transient enabler state to "disabled" */
 489         session->tstate = 0;
 490         lttng_session_sync_enablers(session);
 491 end:
 492         return ret;
 493 }
 494
 495 int lttng_channel_enable(struct lttng_channel *channel)
 496 {
 497         int ret = 0;
 498
 499         if (channel->enabled) {
 500                 ret = -EBUSY;
 501                 goto end;
 502         }
 503         /* Set transient enabler state to "enabled" */
 504         channel->tstate = 1;
 505         lttng_session_sync_enablers(channel->session);
 506         /* Set atomically the state to "enabled" */
 507         CMM_ACCESS_ONCE(channel->enabled) = 1;
 508 end:
 509         return ret;
 510 }
 511
 512 int lttng_channel_disable(struct lttng_channel *channel)
 513 {
 514         int ret = 0;
 515
 516         if (!channel->enabled) {
 517                 ret = -EBUSY;
 518                 goto end;
 519         }
 520         /* Set atomically the state to "disabled" */
 521         CMM_ACCESS_ONCE(channel->enabled) = 0;
 522         /* Set transient enabler state to "enabled" */
 523         channel->tstate = 0;
 524         lttng_session_sync_enablers(channel->session);
 525 end:
 526         return ret;
 527 }
 528
 529 /*
 530  * Supports event creation while tracing session is active.
 531  */
 532 static
 533 int lttng_event_create(const struct lttng_event_desc *desc,
 534                 struct lttng_channel *chan)
 535 {
 536         const char *event_name = desc->name;
 537         struct lttng_event *event;
 538         struct lttng_session *session = chan->session;
 539         struct cds_hlist_head *head;
 540         struct cds_hlist_node *node;
 541         int ret = 0;
 542         size_t name_len = strlen(event_name);
 543         uint32_t hash;
 544         int notify_socket, loglevel;
 545         const char *uri;
 546
 547         hash = jhash(event_name, name_len, 0);
 548         head = &chan->session->events_ht.table[hash & (LTTNG_UST_EVENT_HT_SIZE - 1)];
 549         cds_hlist_for_each_entry(event, node, head, hlist) {
 550                 assert(event->desc);
 551                 if (!strncmp(event->desc->name, desc->name,
 552                                         LTTNG_UST_SYM_NAME_LEN - 1)
 553                                 && chan == event->chan) {
 554                         ret = -EEXIST;
 555                         goto exist;
 556                 }
 557         }
 558
 559         notify_socket = lttng_get_notify_socket(session->owner);
 560         if (notify_socket < 0) {
 561                 ret = notify_socket;
 562                 goto socket_error;
 563         }
 564
 565         ret = lttng_create_all_event_enums(desc->nr_fields, desc->fields,
 566                         session);
 567         if (ret < 0) {
 568                 DBG("Error (%d) adding enum to session", ret);
 569                 goto create_enum_error;
 570         }
 571
 572         /*
 573          * Check if loglevel match. Refuse to connect event if not.
 574          */
 575         event = zmalloc(sizeof(struct lttng_event));
 576         if (!event) {
 577                 ret = -ENOMEM;
 578                 goto cache_error;
 579         }
 580         event->chan = chan;
 581
 582         /* Event will be enabled by enabler sync. */
 583         event->enabled = 0;
 584         event->registered = 0;
 585         CDS_INIT_LIST_HEAD(&event->bytecode_runtime_head);
 586         CDS_INIT_LIST_HEAD(&event->enablers_ref_head);
 587         event->desc = desc;
 588
 589         if (desc->loglevel)
 590                 loglevel = *(*event->desc->loglevel);
 591         else
 592                 loglevel = TRACE_DEFAULT;
 593         if (desc->u.ext.model_emf_uri)
 594                 uri = *(desc->u.ext.model_emf_uri);
 595         else
 596                 uri = NULL;
 597
 598         /* Fetch event ID from sessiond */
 599         ret = ustcomm_register_event(notify_socket,
 600                 session,
 601                 session->objd,
 602                 chan->objd,
 603                 event_name,
 604                 loglevel,
 605                 desc->signature,
 606                 desc->nr_fields,
 607                 desc->fields,
 608                 uri,
 609                 &event->id);
 610         if (ret < 0) {
 611                 DBG("Error (%d) registering event to sessiond", ret);
 612                 goto sessiond_register_error;
 613         }
 614
 615         /* Populate lttng_event structure before tracepoint registration. */
 616         cmm_smp_wmb();
 617         cds_list_add(&event->node, &chan->session->events_head);
 618         cds_hlist_add_head(&event->hlist, head);
 619         return 0;
 620
 621 sessiond_register_error:
 622         free(event);
 623 cache_error:
 624 create_enum_error:
 625 socket_error:
 626 exist:
 627         return ret;
 628 }
 629
 630 static
 631 int lttng_desc_match_star_glob_enabler(const struct lttng_event_desc *desc,
 632                 struct lttng_enabler *enabler)
 633 {
 634         int loglevel = 0;
 635         unsigned int has_loglevel = 0;
 636
 637         assert(enabler->type == LTTNG_ENABLER_STAR_GLOB);
 638         if (!strutils_star_glob_match(enabler->event_param.name, SIZE_MAX,
 639                         desc->name, SIZE_MAX))
 640                 return 0;
 641         if (desc->loglevel) {
 642                 loglevel = *(*desc->loglevel);
 643                 has_loglevel = 1;
 644         }
 645         if (!lttng_loglevel_match(loglevel,
 646                         has_loglevel,
 647                         enabler->event_param.loglevel_type,
 648                         enabler->event_param.loglevel))
 649                 return 0;
 650         return 1;
 651 }
 652
 653 static
 654 int lttng_desc_match_event_enabler(const struct lttng_event_desc *desc,
 655                 struct lttng_enabler *enabler)
 656 {
 657         int loglevel = 0;
 658         unsigned int has_loglevel = 0;
 659
 660         assert(enabler->type == LTTNG_ENABLER_EVENT);
 661         if (strcmp(desc->name, enabler->event_param.name))
 662                 return 0;
 663         if (desc->loglevel) {
 664                 loglevel = *(*desc->loglevel);
 665                 has_loglevel = 1;
 666         }
 667         if (!lttng_loglevel_match(loglevel,
 668                         has_loglevel,
 669                         enabler->event_param.loglevel_type,
 670                         enabler->event_param.loglevel))
 671                 return 0;
 672         return 1;
 673 }
 674
 675 static
 676 int lttng_desc_match_enabler(const struct lttng_event_desc *desc,
 677                 struct lttng_enabler *enabler)
 678 {
 679         switch (enabler->type) {
 680         case LTTNG_ENABLER_STAR_GLOB:
 681         {
 682                 struct lttng_ust_excluder_node *excluder;
 683
 684                 if (!lttng_desc_match_star_glob_enabler(desc, enabler)) {
 685                         return 0;
 686                 }
 687
 688                 /*
 689                  * If the matching event matches with an excluder,
 690                  * return 'does not match'
 691                  */
 692                 cds_list_for_each_entry(excluder, &enabler->excluder_head, node) {
 693                         int count;
 694
 695                         for (count = 0; count < excluder->excluder.count; count++) {
 696                                 int len;
 697                                 char *excluder_name;
 698
 699                                 excluder_name = (char *) (excluder->excluder.names)
 700                                                 + count * LTTNG_UST_SYM_NAME_LEN;
 701                                 len = strnlen(excluder_name, LTTNG_UST_SYM_NAME_LEN);
 702                                 if (len > 0 && strutils_star_glob_match(excluder_name, len, desc->name, SIZE_MAX))
 703                                         return 0;
 704                         }
 705                 }
 706                 return 1;
 707         }
 708         case LTTNG_ENABLER_EVENT:
 709                 return lttng_desc_match_event_enabler(desc, enabler);
 710         default:
 711                 return -EINVAL;
 712         }
 713 }
 714
 715 static
 716 int lttng_event_match_enabler(struct lttng_event *event,
 717                 struct lttng_enabler *enabler)
 718 {
 719         if (lttng_desc_match_enabler(event->desc, enabler)
 720                         && event->chan == enabler->chan)
 721                 return 1;
 722         else
 723                 return 0;
 724 }
 725
 726 static
 727 struct lttng_enabler_ref * lttng_event_enabler_ref(struct lttng_event *event,
 728                 struct lttng_enabler *enabler)
 729 {
 730         struct lttng_enabler_ref *enabler_ref;
 731
 732         cds_list_for_each_entry(enabler_ref,
 733                         &event->enablers_ref_head, node) {
 734                 if (enabler_ref->ref == enabler)
 735                         return enabler_ref;
 736         }
 737         return NULL;
 738 }
 739
 740 /*
 741  * Create struct lttng_event if it is missing and present in the list of
 742  * tracepoint probes.
 743  */
 744 static
 745 void lttng_create_event_if_missing(struct lttng_enabler *enabler)
 746 {
 747         struct lttng_session *session = enabler->chan->session;
 748         struct lttng_probe_desc *probe_desc;
 749         const struct lttng_event_desc *desc;
 750         struct lttng_event *event;
 751         int i;
 752         struct cds_list_head *probe_list;
 753
 754         probe_list = lttng_get_probe_list_head();
 755         /*
 756          * For each probe event, if we find that a probe event matches
 757          * our enabler, create an associated lttng_event if not
 758          * already present.
 759          */
 760         cds_list_for_each_entry(probe_desc, probe_list, head) {
 761                 for (i = 0; i < probe_desc->nr_events; i++) {
 762                         int found = 0, ret;
 763                         struct cds_hlist_head *head;
 764                         struct cds_hlist_node *node;
 765                         const char *event_name;
 766                         size_t name_len;
 767                         uint32_t hash;
 768
 769                         desc = probe_desc->event_desc[i];
 770                         if (!lttng_desc_match_enabler(desc, enabler))
 771                                 continue;
 772                         event_name = desc->name;
 773                         name_len = strlen(event_name);
 774
 775                         /*
 776                          * Check if already created.
 777                          */
 778                         hash = jhash(event_name, name_len, 0);
 779                         head = &session->events_ht.table[hash & (LTTNG_UST_EVENT_HT_SIZE - 1)];
 780                         cds_hlist_for_each_entry(event, node, head, hlist) {
 781                                 if (event->desc == desc
 782                                                 && event->chan == enabler->chan)
 783                                         found = 1;
 784                         }
 785                         if (found)
 786                                 continue;
 787
 788                         /*
 789                          * We need to create an event for this
 790                          * event probe.
 791                          */
 792                         ret = lttng_event_create(probe_desc->event_desc[i],
 793                                         enabler->chan);
 794                         if (ret) {
 795                                 DBG("Unable to create event %s, error %d\n",
 796                                         probe_desc->event_desc[i]->name, ret);
 797                         }
 798                 }
 799         }
 800 }
 801
 802 /*
 803  * Create events associated with an enabler (if not already present),
 804  * and add backward reference from the event to the enabler.
 805  */
 806 static
 807 int lttng_enabler_ref_events(struct lttng_enabler *enabler)
 808 {
 809         struct lttng_session *session = enabler->chan->session;
 810         struct lttng_event *event;
 811
 812         /* First ensure that probe events are created for this enabler. */
 813         lttng_create_event_if_missing(enabler);
 814
 815         /* For each event matching enabler in session event list. */
 816         cds_list_for_each_entry(event, &session->events_head, node) {
 817                 struct lttng_enabler_ref *enabler_ref;
 818
 819                 if (!lttng_event_match_enabler(event, enabler))
 820                         continue;
 821
 822                 enabler_ref = lttng_event_enabler_ref(event, enabler);
 823                 if (!enabler_ref) {
 824                         /*
 825                          * If no backward ref, create it.
 826                          * Add backward ref from event to enabler.
 827                          */
 828                         enabler_ref = zmalloc(sizeof(*enabler_ref));
 829                         if (!enabler_ref)
 830                                 return -ENOMEM;
 831                         enabler_ref->ref = enabler;
 832                         cds_list_add(&enabler_ref->node,
 833                                 &event->enablers_ref_head);
 834                 }
 835
 836                 /*
 837                  * Link filter bytecodes if not linked yet.
 838                  */
 839                 lttng_enabler_event_link_bytecode(event, enabler);
 840
 841                 /* TODO: merge event context. */
 842         }
 843         return 0;
 844 }
 845
 846 /*
 847  * Called at library load: connect the probe on all enablers matching
 848  * this event.
 849  * Called with session mutex held.
 850  */
 851 int lttng_fix_pending_events(void)
 852 {
 853         struct lttng_session *session;
 854
 855         cds_list_for_each_entry(session, &sessions, node) {
 856                 lttng_session_lazy_sync_enablers(session);
 857         }
 858         return 0;
 859 }
 860
 861 /*
 862  * For each session of the owner thread, execute pending statedump.
 863  * Only dump state for the sessions owned by the caller thread, because
 864  * we don't keep ust_lock across the entire iteration.
 865  */
 866 void lttng_handle_pending_statedump(void *owner)
 867 {
 868         struct lttng_session *session;
 869
 870         /* Execute state dump */
 871         do_lttng_ust_statedump(owner);
 872
 873         /* Clear pending state dump */
 874         if (ust_lock()) {
 875                 goto end;
 876         }
 877         cds_list_for_each_entry(session, &sessions, node) {
 878                 if (session->owner != owner)
 879                         continue;
 880                 if (!session->statedump_pending)
 881                         continue;
 882                 session->statedump_pending = 0;
 883         }
 884 end:
 885         ust_unlock();
 886         return;
 887 }
 888
 889 /*
 890  * Only used internally at session destruction.
 891  */
 892 static
 893 void _lttng_event_destroy(struct lttng_event *event)
 894 {
 895         struct lttng_enabler_ref *enabler_ref, *tmp_enabler_ref;
 896
 897         cds_list_del(&event->node);
 898         lttng_destroy_context(event->ctx);
 899         lttng_free_event_filter_runtime(event);
 900         /* Free event enabler refs */
 901         cds_list_for_each_entry_safe(enabler_ref, tmp_enabler_ref,
 902                         &event->enablers_ref_head, node)
 903                 free(enabler_ref);
 904         free(event);
 905 }
 906
 907 static
 908 void _lttng_enum_destroy(struct lttng_enum *_enum)
 909 {
 910         cds_list_del(&_enum->node);
 911         free(_enum);
 912 }
 913
 914 void lttng_ust_events_exit(void)
 915 {
 916         struct lttng_session *session, *tmpsession;
 917
 918         cds_list_for_each_entry_safe(session, tmpsession, &sessions, node)
 919                 lttng_session_destroy(session);
 920 }
 921
 922 /*
 923  * Enabler management.
 924  */
 925 struct lttng_enabler *lttng_enabler_create(enum lttng_enabler_type type,
 926                 struct lttng_ust_event *event_param,
 927                 struct lttng_channel *chan)
 928 {
 929         struct lttng_enabler *enabler;
 930
 931         enabler = zmalloc(sizeof(*enabler));
 932         if (!enabler)
 933                 return NULL;
 934         enabler->type = type;
 935         CDS_INIT_LIST_HEAD(&enabler->filter_bytecode_head);
 936         CDS_INIT_LIST_HEAD(&enabler->excluder_head);
 937         memcpy(&enabler->event_param, event_param,
 938                 sizeof(enabler->event_param));
 939         enabler->chan = chan;
 940         /* ctx left NULL */
 941         enabler->enabled = 0;
 942         cds_list_add(&enabler->node, &enabler->chan->session->enablers_head);
 943         lttng_session_lazy_sync_enablers(enabler->chan->session);
 944         return enabler;
 945 }
 946
 947 int lttng_enabler_enable(struct lttng_enabler *enabler)
 948 {
 949         enabler->enabled = 1;
 950         lttng_session_lazy_sync_enablers(enabler->chan->session);
 951         return 0;
 952 }
 953
 954 int lttng_enabler_disable(struct lttng_enabler *enabler)
 955 {
 956         enabler->enabled = 0;
 957         lttng_session_lazy_sync_enablers(enabler->chan->session);
 958         return 0;
 959 }
 960
 961 int lttng_enabler_attach_bytecode(struct lttng_enabler *enabler,
 962                 struct lttng_ust_filter_bytecode_node *bytecode)
 963 {
 964         bytecode->enabler = enabler;
 965         cds_list_add_tail(&bytecode->node, &enabler->filter_bytecode_head);
 966         lttng_session_lazy_sync_enablers(enabler->chan->session);
 967         return 0;
 968 }
 969
 970 int lttng_enabler_attach_exclusion(struct lttng_enabler *enabler,
 971                 struct lttng_ust_excluder_node *excluder)
 972 {
 973         excluder->enabler = enabler;
 974         cds_list_add_tail(&excluder->node, &enabler->excluder_head);
 975         lttng_session_lazy_sync_enablers(enabler->chan->session);
 976         return 0;
 977 }
 978
 979 int lttng_attach_context(struct lttng_ust_context *context_param,
 980                 union ust_args *uargs,
 981                 struct lttng_ctx **ctx, struct lttng_session *session)
 982 {
 983         /*
 984          * We cannot attach a context after trace has been started for a
 985          * session because the metadata does not allow expressing this
 986          * information outside of the original channel scope.
 987          */
 988         if (session->been_active)
 989                 return -EPERM;
 990
 991         switch (context_param->ctx) {
 992         case LTTNG_UST_CONTEXT_PTHREAD_ID:
 993                 return lttng_add_pthread_id_to_ctx(ctx);
 994         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
 995         {
 996                 struct lttng_ust_perf_counter_ctx *perf_ctx_param;
 997
 998                 perf_ctx_param = &context_param->u.perf_counter;
 999                 return lttng_add_perf_counter_to_ctx(
1000                         perf_ctx_param->type,
1001                         perf_ctx_param->config,
1002                         perf_ctx_param->name,
1003                         ctx);
1004         }
1005         case LTTNG_UST_CONTEXT_VTID:
1006                 return lttng_add_vtid_to_ctx(ctx);
1007         case LTTNG_UST_CONTEXT_VPID:
1008                 return lttng_add_vpid_to_ctx(ctx);
1009         case LTTNG_UST_CONTEXT_PROCNAME:
1010                 return lttng_add_procname_to_ctx(ctx);
1011         case LTTNG_UST_CONTEXT_IP:
1012                 return lttng_add_ip_to_ctx(ctx);
1013         case LTTNG_UST_CONTEXT_CPU_ID:
1014                 return lttng_add_cpu_id_to_ctx(ctx);
1015         case LTTNG_UST_CONTEXT_APP_CONTEXT:
1016                 return lttng_ust_add_app_context_to_ctx_rcu(uargs->app_context.ctxname,
1017                         ctx);
1018         default:
1019                 return -EINVAL;
1020         }
1021 }
1022
1023 int lttng_enabler_attach_context(struct lttng_enabler *enabler,
1024                 struct lttng_ust_context *context_param)
1025 {
1026 #if 0   // disabled for now.
1027         struct lttng_session *session = enabler->chan->session;
1028         int ret;
1029
1030         ret = lttng_attach_context(context_param, &enabler->ctx,
1031                         session);
1032         if (ret)
1033                 return ret;
1034         lttng_session_lazy_sync_enablers(enabler->chan->session);
1035 #endif
1036         return -ENOSYS;
1037 }
1038
1039 static
1040 void lttng_enabler_destroy(struct lttng_enabler *enabler)
1041 {
1042         struct lttng_ust_filter_bytecode_node *filter_node, *tmp_filter_node;
1043         struct lttng_ust_excluder_node *excluder_node, *tmp_excluder_node;
1044
1045         /* Destroy filter bytecode */
1046         cds_list_for_each_entry_safe(filter_node, tmp_filter_node,
1047                         &enabler->filter_bytecode_head, node) {
1048                 free(filter_node);
1049         }
1050
1051         /* Destroy excluders */
1052         cds_list_for_each_entry_safe(excluder_node, tmp_excluder_node,
1053                         &enabler->excluder_head, node) {
1054                 free(excluder_node);
1055         }
1056
1057         /* Destroy contexts */
1058         lttng_destroy_context(enabler->ctx);
1059
1060         cds_list_del(&enabler->node);
1061         free(enabler);
1062 }
1063
1064 /*
1065  * lttng_session_sync_enablers should be called just before starting a
1066  * session.
1067  */
1068 static
1069 void lttng_session_sync_enablers(struct lttng_session *session)
1070 {
1071         struct lttng_enabler *enabler;
1072         struct lttng_event *event;
1073
1074         cds_list_for_each_entry(enabler, &session->enablers_head, node)
1075                 lttng_enabler_ref_events(enabler);
1076         /*
1077          * For each event, if at least one of its enablers is enabled,
1078          * and its channel and session transient states are enabled, we
1079          * enable the event, else we disable it.
1080          */
1081         cds_list_for_each_entry(event, &session->events_head, node) {
1082                 struct lttng_enabler_ref *enabler_ref;
1083                 struct lttng_bytecode_runtime *runtime;
1084                 int enabled = 0, has_enablers_without_bytecode = 0;
1085
1086                 /* Enable events */
1087                 cds_list_for_each_entry(enabler_ref,
1088                                 &event->enablers_ref_head, node) {
1089                         if (enabler_ref->ref->enabled) {
1090                                 enabled = 1;
1091                                 break;
1092                         }
1093                 }
1094                 /*
1095                  * Enabled state is based on union of enablers, with
1096                  * intesection of session and channel transient enable
1097                  * states.
1098                  */
1099                 enabled = enabled && session->tstate && event->chan->tstate;
1100
1101                 CMM_STORE_SHARED(event->enabled, enabled);
1102                 /*
1103                  * Sync tracepoint registration with event enabled
1104                  * state.
1105                  */
1106                 if (enabled) {
1107                         if (!event->registered)
1108                                 register_event(event);
1109                 } else {
1110                         if (event->registered)
1111                                 unregister_event(event);
1112                 }
1113
1114                 /* Check if has enablers without bytecode enabled */
1115                 cds_list_for_each_entry(enabler_ref,
1116                                 &event->enablers_ref_head, node) {
1117                         if (enabler_ref->ref->enabled
1118                                         && cds_list_empty(&enabler_ref->ref->filter_bytecode_head)) {
1119                                 has_enablers_without_bytecode = 1;
1120                                 break;
1121                         }
1122                 }
1123                 event->has_enablers_without_bytecode =
1124                         has_enablers_without_bytecode;
1125
1126                 /* Enable filters */
1127                 cds_list_for_each_entry(runtime,
1128                                 &event->bytecode_runtime_head, node) {
1129                         lttng_filter_sync_state(runtime);
1130                 }
1131         }
1132         __tracepoint_probe_prune_release_queue();
1133 }
1134
1135 /*
1136  * Apply enablers to session events, adding events to session if need
1137  * be. It is required after each modification applied to an active
1138  * session, and right before session "start".
1139  * "lazy" sync means we only sync if required.
1140  */
1141 static
1142 void lttng_session_lazy_sync_enablers(struct lttng_session *session)
1143 {
1144         /* We can skip if session is not active */
1145         if (!session->active)
1146                 return;
1147         lttng_session_sync_enablers(session);
1148 }
1149
1150 /*
1151  * Update all sessions with the given app context.
1152  * Called with ust lock held.
1153  * This is invoked when an application context gets loaded/unloaded. It
1154  * ensures the context callbacks are in sync with the application
1155  * context (either app context callbacks, or dummy callbacks).
1156  */
1157 void lttng_ust_context_set_session_provider(const char *name,
1158                 size_t (*get_size)(struct lttng_ctx_field *field, size_t offset),
1159                 void (*record)(struct lttng_ctx_field *field,
1160                         struct lttng_ust_lib_ring_buffer_ctx *ctx,
1161                         struct lttng_channel *chan),
1162                 void (*get_value)(struct lttng_ctx_field *field,
1163                         struct lttng_ctx_value *value))
1164 {
1165         struct lttng_session *session;
1166
1167         cds_list_for_each_entry(session, &sessions, node) {
1168                 struct lttng_channel *chan;
1169                 struct lttng_event *event;
1170                 int ret;
1171
1172                 ret = lttng_ust_context_set_provider_rcu(&session->ctx,
1173                                 name, get_size, record, get_value);
1174                 if (ret)
1175                         abort();
1176                 cds_list_for_each_entry(chan, &session->chan_head, node) {
1177                         ret = lttng_ust_context_set_provider_rcu(&chan->ctx,
1178                                         name, get_size, record, get_value);
1179                         if (ret)
1180                                 abort();
1181                 }
1182                 cds_list_for_each_entry(event, &session->events_head, node) {
1183                         ret = lttng_ust_context_set_provider_rcu(&event->ctx,
1184                                         name, get_size, record, get_value);
1185                         if (ret)
1186                                 abort();
1187                 }
1188         }
1189 }