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         int ret = 0;
 541         size_t name_len = strlen(event_name);
 542         uint32_t hash;
 543         int notify_socket, loglevel;
 544         const char *uri;
 545
 546         hash = jhash(event_name, name_len, 0);
 547         head = &chan->session->events_ht.table[hash & (LTTNG_UST_EVENT_HT_SIZE - 1)];
 548
 549         notify_socket = lttng_get_notify_socket(session->owner);
 550         if (notify_socket < 0) {
 551                 ret = notify_socket;
 552                 goto socket_error;
 553         }
 554
 555         ret = lttng_create_all_event_enums(desc->nr_fields, desc->fields,
 556                         session);
 557         if (ret < 0) {
 558                 DBG("Error (%d) adding enum to session", ret);
 559                 goto create_enum_error;
 560         }
 561
 562         /*
 563          * Check if loglevel match. Refuse to connect event if not.
 564          */
 565         event = zmalloc(sizeof(struct lttng_event));
 566         if (!event) {
 567                 ret = -ENOMEM;
 568                 goto cache_error;
 569         }
 570         event->chan = chan;
 571
 572         /* Event will be enabled by enabler sync. */
 573         event->enabled = 0;
 574         event->registered = 0;
 575         CDS_INIT_LIST_HEAD(&event->bytecode_runtime_head);
 576         CDS_INIT_LIST_HEAD(&event->enablers_ref_head);
 577         event->desc = desc;
 578
 579         if (desc->loglevel)
 580                 loglevel = *(*event->desc->loglevel);
 581         else
 582                 loglevel = TRACE_DEFAULT;
 583         if (desc->u.ext.model_emf_uri)
 584                 uri = *(desc->u.ext.model_emf_uri);
 585         else
 586                 uri = NULL;
 587
 588         /* Fetch event ID from sessiond */
 589         ret = ustcomm_register_event(notify_socket,
 590                 session,
 591                 session->objd,
 592                 chan->objd,
 593                 event_name,
 594                 loglevel,
 595                 desc->signature,
 596                 desc->nr_fields,
 597                 desc->fields,
 598                 uri,
 599                 &event->id);
 600         if (ret < 0) {
 601                 DBG("Error (%d) registering event to sessiond", ret);
 602                 goto sessiond_register_error;
 603         }
 604
 605         /* Populate lttng_event structure before tracepoint registration. */
 606         cmm_smp_wmb();
 607         cds_list_add(&event->node, &chan->session->events_head);
 608         cds_hlist_add_head(&event->hlist, head);
 609         return 0;
 610
 611 sessiond_register_error:
 612         free(event);
 613 cache_error:
 614 create_enum_error:
 615 socket_error:
 616         return ret;
 617 }
 618
 619 static
 620 int lttng_desc_match_star_glob_enabler(const struct lttng_event_desc *desc,
 621                 struct lttng_enabler *enabler)
 622 {
 623         int loglevel = 0;
 624         unsigned int has_loglevel = 0;
 625
 626         assert(enabler->type == LTTNG_ENABLER_STAR_GLOB);
 627         if (!strutils_star_glob_match(enabler->event_param.name, SIZE_MAX,
 628                         desc->name, SIZE_MAX))
 629                 return 0;
 630         if (desc->loglevel) {
 631                 loglevel = *(*desc->loglevel);
 632                 has_loglevel = 1;
 633         }
 634         if (!lttng_loglevel_match(loglevel,
 635                         has_loglevel,
 636                         enabler->event_param.loglevel_type,
 637                         enabler->event_param.loglevel))
 638                 return 0;
 639         return 1;
 640 }
 641
 642 static
 643 int lttng_desc_match_event_enabler(const struct lttng_event_desc *desc,
 644                 struct lttng_enabler *enabler)
 645 {
 646         int loglevel = 0;
 647         unsigned int has_loglevel = 0;
 648
 649         assert(enabler->type == LTTNG_ENABLER_EVENT);
 650         if (strcmp(desc->name, enabler->event_param.name))
 651                 return 0;
 652         if (desc->loglevel) {
 653                 loglevel = *(*desc->loglevel);
 654                 has_loglevel = 1;
 655         }
 656         if (!lttng_loglevel_match(loglevel,
 657                         has_loglevel,
 658                         enabler->event_param.loglevel_type,
 659                         enabler->event_param.loglevel))
 660                 return 0;
 661         return 1;
 662 }
 663
 664 static
 665 int lttng_desc_match_enabler(const struct lttng_event_desc *desc,
 666                 struct lttng_enabler *enabler)
 667 {
 668         switch (enabler->type) {
 669         case LTTNG_ENABLER_STAR_GLOB:
 670         {
 671                 struct lttng_ust_excluder_node *excluder;
 672
 673                 if (!lttng_desc_match_star_glob_enabler(desc, enabler)) {
 674                         return 0;
 675                 }
 676
 677                 /*
 678                  * If the matching event matches with an excluder,
 679                  * return 'does not match'
 680                  */
 681                 cds_list_for_each_entry(excluder, &enabler->excluder_head, node) {
 682                         int count;
 683
 684                         for (count = 0; count < excluder->excluder.count; count++) {
 685                                 int len;
 686                                 char *excluder_name;
 687
 688                                 excluder_name = (char *) (excluder->excluder.names)
 689                                                 + count * LTTNG_UST_SYM_NAME_LEN;
 690                                 len = strnlen(excluder_name, LTTNG_UST_SYM_NAME_LEN);
 691                                 if (len > 0 && strutils_star_glob_match(excluder_name, len, desc->name, SIZE_MAX))
 692                                         return 0;
 693                         }
 694                 }
 695                 return 1;
 696         }
 697         case LTTNG_ENABLER_EVENT:
 698                 return lttng_desc_match_event_enabler(desc, enabler);
 699         default:
 700                 return -EINVAL;
 701         }
 702 }
 703
 704 static
 705 int lttng_event_match_enabler(struct lttng_event *event,
 706                 struct lttng_enabler *enabler)
 707 {
 708         if (lttng_desc_match_enabler(event->desc, enabler)
 709                         && event->chan == enabler->chan)
 710                 return 1;
 711         else
 712                 return 0;
 713 }
 714
 715 static
 716 struct lttng_enabler_ref * lttng_event_enabler_ref(struct lttng_event *event,
 717                 struct lttng_enabler *enabler)
 718 {
 719         struct lttng_enabler_ref *enabler_ref;
 720
 721         cds_list_for_each_entry(enabler_ref,
 722                         &event->enablers_ref_head, node) {
 723                 if (enabler_ref->ref == enabler)
 724                         return enabler_ref;
 725         }
 726         return NULL;
 727 }
 728
 729 /*
 730  * Create struct lttng_event if it is missing and present in the list of
 731  * tracepoint probes.
 732  */
 733 static
 734 void lttng_create_event_if_missing(struct lttng_enabler *enabler)
 735 {
 736         struct lttng_session *session = enabler->chan->session;
 737         struct lttng_probe_desc *probe_desc;
 738         const struct lttng_event_desc *desc;
 739         struct lttng_event *event;
 740         int i;
 741         struct cds_list_head *probe_list;
 742
 743         probe_list = lttng_get_probe_list_head();
 744         /*
 745          * For each probe event, if we find that a probe event matches
 746          * our enabler, create an associated lttng_event if not
 747          * already present.
 748          */
 749         cds_list_for_each_entry(probe_desc, probe_list, head) {
 750                 for (i = 0; i < probe_desc->nr_events; i++) {
 751                         int found = 0, ret;
 752                         struct cds_hlist_head *head;
 753                         struct cds_hlist_node *node;
 754                         const char *event_name;
 755                         size_t name_len;
 756                         uint32_t hash;
 757
 758                         desc = probe_desc->event_desc[i];
 759                         if (!lttng_desc_match_enabler(desc, enabler))
 760                                 continue;
 761                         event_name = desc->name;
 762                         name_len = strlen(event_name);
 763
 764                         /*
 765                          * Check if already created.
 766                          */
 767                         hash = jhash(event_name, name_len, 0);
 768                         head = &session->events_ht.table[hash & (LTTNG_UST_EVENT_HT_SIZE - 1)];
 769                         cds_hlist_for_each_entry(event, node, head, hlist) {
 770                                 if (event->desc == desc
 771                                                 && event->chan == enabler->chan)
 772                                         found = 1;
 773                         }
 774                         if (found)
 775                                 continue;
 776
 777                         /*
 778                          * We need to create an event for this
 779                          * event probe.
 780                          */
 781                         ret = lttng_event_create(probe_desc->event_desc[i],
 782                                         enabler->chan);
 783                         if (ret) {
 784                                 DBG("Unable to create event %s, error %d\n",
 785                                         probe_desc->event_desc[i]->name, ret);
 786                         }
 787                 }
 788         }
 789 }
 790
 791 /*
 792  * Create events associated with an enabler (if not already present),
 793  * and add backward reference from the event to the enabler.
 794  */
 795 static
 796 int lttng_enabler_ref_events(struct lttng_enabler *enabler)
 797 {
 798         struct lttng_session *session = enabler->chan->session;
 799         struct lttng_event *event;
 800
 801         /* First ensure that probe events are created for this enabler. */
 802         lttng_create_event_if_missing(enabler);
 803
 804         /* For each event matching enabler in session event list. */
 805         cds_list_for_each_entry(event, &session->events_head, node) {
 806                 struct lttng_enabler_ref *enabler_ref;
 807
 808                 if (!lttng_event_match_enabler(event, enabler))
 809                         continue;
 810
 811                 enabler_ref = lttng_event_enabler_ref(event, enabler);
 812                 if (!enabler_ref) {
 813                         /*
 814                          * If no backward ref, create it.
 815                          * Add backward ref from event to enabler.
 816                          */
 817                         enabler_ref = zmalloc(sizeof(*enabler_ref));
 818                         if (!enabler_ref)
 819                                 return -ENOMEM;
 820                         enabler_ref->ref = enabler;
 821                         cds_list_add(&enabler_ref->node,
 822                                 &event->enablers_ref_head);
 823                 }
 824
 825                 /*
 826                  * Link filter bytecodes if not linked yet.
 827                  */
 828                 lttng_enabler_event_link_bytecode(event, enabler);
 829
 830                 /* TODO: merge event context. */
 831         }
 832         return 0;
 833 }
 834
 835 /*
 836  * Called at library load: connect the probe on all enablers matching
 837  * this event.
 838  * Called with session mutex held.
 839  */
 840 int lttng_fix_pending_events(void)
 841 {
 842         struct lttng_session *session;
 843
 844         cds_list_for_each_entry(session, &sessions, node) {
 845                 lttng_session_lazy_sync_enablers(session);
 846         }
 847         return 0;
 848 }
 849
 850 /*
 851  * For each session of the owner thread, execute pending statedump.
 852  * Only dump state for the sessions owned by the caller thread, because
 853  * we don't keep ust_lock across the entire iteration.
 854  */
 855 void lttng_handle_pending_statedump(void *owner)
 856 {
 857         struct lttng_session *session;
 858
 859         /* Execute state dump */
 860         do_lttng_ust_statedump(owner);
 861
 862         /* Clear pending state dump */
 863         if (ust_lock()) {
 864                 goto end;
 865         }
 866         cds_list_for_each_entry(session, &sessions, node) {
 867                 if (session->owner != owner)
 868                         continue;
 869                 if (!session->statedump_pending)
 870                         continue;
 871                 session->statedump_pending = 0;
 872         }
 873 end:
 874         ust_unlock();
 875         return;
 876 }
 877
 878 /*
 879  * Only used internally at session destruction.
 880  */
 881 static
 882 void _lttng_event_destroy(struct lttng_event *event)
 883 {
 884         struct lttng_enabler_ref *enabler_ref, *tmp_enabler_ref;
 885
 886         cds_list_del(&event->node);
 887         lttng_destroy_context(event->ctx);
 888         lttng_free_event_filter_runtime(event);
 889         /* Free event enabler refs */
 890         cds_list_for_each_entry_safe(enabler_ref, tmp_enabler_ref,
 891                         &event->enablers_ref_head, node)
 892                 free(enabler_ref);
 893         free(event);
 894 }
 895
 896 static
 897 void _lttng_enum_destroy(struct lttng_enum *_enum)
 898 {
 899         cds_list_del(&_enum->node);
 900         free(_enum);
 901 }
 902
 903 void lttng_ust_events_exit(void)
 904 {
 905         struct lttng_session *session, *tmpsession;
 906
 907         cds_list_for_each_entry_safe(session, tmpsession, &sessions, node)
 908                 lttng_session_destroy(session);
 909 }
 910
 911 /*
 912  * Enabler management.
 913  */
 914 struct lttng_enabler *lttng_enabler_create(enum lttng_enabler_type type,
 915                 struct lttng_ust_event *event_param,
 916                 struct lttng_channel *chan)
 917 {
 918         struct lttng_enabler *enabler;
 919
 920         enabler = zmalloc(sizeof(*enabler));
 921         if (!enabler)
 922                 return NULL;
 923         enabler->type = type;
 924         CDS_INIT_LIST_HEAD(&enabler->filter_bytecode_head);
 925         CDS_INIT_LIST_HEAD(&enabler->excluder_head);
 926         memcpy(&enabler->event_param, event_param,
 927                 sizeof(enabler->event_param));
 928         enabler->chan = chan;
 929         /* ctx left NULL */
 930         enabler->enabled = 0;
 931         cds_list_add(&enabler->node, &enabler->chan->session->enablers_head);
 932         lttng_session_lazy_sync_enablers(enabler->chan->session);
 933         return enabler;
 934 }
 935
 936 int lttng_enabler_enable(struct lttng_enabler *enabler)
 937 {
 938         enabler->enabled = 1;
 939         lttng_session_lazy_sync_enablers(enabler->chan->session);
 940         return 0;
 941 }
 942
 943 int lttng_enabler_disable(struct lttng_enabler *enabler)
 944 {
 945         enabler->enabled = 0;
 946         lttng_session_lazy_sync_enablers(enabler->chan->session);
 947         return 0;
 948 }
 949
 950 int lttng_enabler_attach_bytecode(struct lttng_enabler *enabler,
 951                 struct lttng_ust_filter_bytecode_node *bytecode)
 952 {
 953         bytecode->enabler = enabler;
 954         cds_list_add_tail(&bytecode->node, &enabler->filter_bytecode_head);
 955         lttng_session_lazy_sync_enablers(enabler->chan->session);
 956         return 0;
 957 }
 958
 959 int lttng_enabler_attach_exclusion(struct lttng_enabler *enabler,
 960                 struct lttng_ust_excluder_node *excluder)
 961 {
 962         excluder->enabler = enabler;
 963         cds_list_add_tail(&excluder->node, &enabler->excluder_head);
 964         lttng_session_lazy_sync_enablers(enabler->chan->session);
 965         return 0;
 966 }
 967
 968 int lttng_attach_context(struct lttng_ust_context *context_param,
 969                 union ust_args *uargs,
 970                 struct lttng_ctx **ctx, struct lttng_session *session)
 971 {
 972         /*
 973          * We cannot attach a context after trace has been started for a
 974          * session because the metadata does not allow expressing this
 975          * information outside of the original channel scope.
 976          */
 977         if (session->been_active)
 978                 return -EPERM;
 979
 980         switch (context_param->ctx) {
 981         case LTTNG_UST_CONTEXT_PTHREAD_ID:
 982                 return lttng_add_pthread_id_to_ctx(ctx);
 983         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
 984         {
 985                 struct lttng_ust_perf_counter_ctx *perf_ctx_param;
 986
 987                 perf_ctx_param = &context_param->u.perf_counter;
 988                 return lttng_add_perf_counter_to_ctx(
 989                         perf_ctx_param->type,
 990                         perf_ctx_param->config,
 991                         perf_ctx_param->name,
 992                         ctx);
 993         }
 994         case LTTNG_UST_CONTEXT_VTID:
 995                 return lttng_add_vtid_to_ctx(ctx);
 996         case LTTNG_UST_CONTEXT_VPID:
 997                 return lttng_add_vpid_to_ctx(ctx);
 998         case LTTNG_UST_CONTEXT_PROCNAME:
 999                 return lttng_add_procname_to_ctx(ctx);
1000         case LTTNG_UST_CONTEXT_IP:
1001                 return lttng_add_ip_to_ctx(ctx);
1002         case LTTNG_UST_CONTEXT_CPU_ID:
1003                 return lttng_add_cpu_id_to_ctx(ctx);
1004         case LTTNG_UST_CONTEXT_APP_CONTEXT:
1005                 return lttng_ust_add_app_context_to_ctx_rcu(uargs->app_context.ctxname,
1006                         ctx);
1007         default:
1008                 return -EINVAL;
1009         }
1010 }
1011
1012 int lttng_enabler_attach_context(struct lttng_enabler *enabler,
1013                 struct lttng_ust_context *context_param)
1014 {
1015 #if 0   // disabled for now.
1016         struct lttng_session *session = enabler->chan->session;
1017         int ret;
1018
1019         ret = lttng_attach_context(context_param, &enabler->ctx,
1020                         session);
1021         if (ret)
1022                 return ret;
1023         lttng_session_lazy_sync_enablers(enabler->chan->session);
1024 #endif
1025         return -ENOSYS;
1026 }
1027
1028 static
1029 void lttng_enabler_destroy(struct lttng_enabler *enabler)
1030 {
1031         struct lttng_ust_filter_bytecode_node *filter_node, *tmp_filter_node;
1032         struct lttng_ust_excluder_node *excluder_node, *tmp_excluder_node;
1033
1034         /* Destroy filter bytecode */
1035         cds_list_for_each_entry_safe(filter_node, tmp_filter_node,
1036                         &enabler->filter_bytecode_head, node) {
1037                 free(filter_node);
1038         }
1039
1040         /* Destroy excluders */
1041         cds_list_for_each_entry_safe(excluder_node, tmp_excluder_node,
1042                         &enabler->excluder_head, node) {
1043                 free(excluder_node);
1044         }
1045
1046         /* Destroy contexts */
1047         lttng_destroy_context(enabler->ctx);
1048
1049         cds_list_del(&enabler->node);
1050         free(enabler);
1051 }
1052
1053 /*
1054  * lttng_session_sync_enablers should be called just before starting a
1055  * session.
1056  */
1057 static
1058 void lttng_session_sync_enablers(struct lttng_session *session)
1059 {
1060         struct lttng_enabler *enabler;
1061         struct lttng_event *event;
1062
1063         cds_list_for_each_entry(enabler, &session->enablers_head, node)
1064                 lttng_enabler_ref_events(enabler);
1065         /*
1066          * For each event, if at least one of its enablers is enabled,
1067          * and its channel and session transient states are enabled, we
1068          * enable the event, else we disable it.
1069          */
1070         cds_list_for_each_entry(event, &session->events_head, node) {
1071                 struct lttng_enabler_ref *enabler_ref;
1072                 struct lttng_bytecode_runtime *runtime;
1073                 int enabled = 0, has_enablers_without_bytecode = 0;
1074
1075                 /* Enable events */
1076                 cds_list_for_each_entry(enabler_ref,
1077                                 &event->enablers_ref_head, node) {
1078                         if (enabler_ref->ref->enabled) {
1079                                 enabled = 1;
1080                                 break;
1081                         }
1082                 }
1083                 /*
1084                  * Enabled state is based on union of enablers, with
1085                  * intesection of session and channel transient enable
1086                  * states.
1087                  */
1088                 enabled = enabled && session->tstate && event->chan->tstate;
1089
1090                 CMM_STORE_SHARED(event->enabled, enabled);
1091                 /*
1092                  * Sync tracepoint registration with event enabled
1093                  * state.
1094                  */
1095                 if (enabled) {
1096                         if (!event->registered)
1097                                 register_event(event);
1098                 } else {
1099                         if (event->registered)
1100                                 unregister_event(event);
1101                 }
1102
1103                 /* Check if has enablers without bytecode enabled */
1104                 cds_list_for_each_entry(enabler_ref,
1105                                 &event->enablers_ref_head, node) {
1106                         if (enabler_ref->ref->enabled
1107                                         && cds_list_empty(&enabler_ref->ref->filter_bytecode_head)) {
1108                                 has_enablers_without_bytecode = 1;
1109                                 break;
1110                         }
1111                 }
1112                 event->has_enablers_without_bytecode =
1113                         has_enablers_without_bytecode;
1114
1115                 /* Enable filters */
1116                 cds_list_for_each_entry(runtime,
1117                                 &event->bytecode_runtime_head, node) {
1118                         lttng_filter_sync_state(runtime);
1119                 }
1120         }
1121         __tracepoint_probe_prune_release_queue();
1122 }
1123
1124 /*
1125  * Apply enablers to session events, adding events to session if need
1126  * be. It is required after each modification applied to an active
1127  * session, and right before session "start".
1128  * "lazy" sync means we only sync if required.
1129  */
1130 static
1131 void lttng_session_lazy_sync_enablers(struct lttng_session *session)
1132 {
1133         /* We can skip if session is not active */
1134         if (!session->active)
1135                 return;
1136         lttng_session_sync_enablers(session);
1137 }
1138
1139 /*
1140  * Update all sessions with the given app context.
1141  * Called with ust lock held.
1142  * This is invoked when an application context gets loaded/unloaded. It
1143  * ensures the context callbacks are in sync with the application
1144  * context (either app context callbacks, or dummy callbacks).
1145  */
1146 void lttng_ust_context_set_session_provider(const char *name,
1147                 size_t (*get_size)(struct lttng_ctx_field *field, size_t offset),
1148                 void (*record)(struct lttng_ctx_field *field,
1149                         struct lttng_ust_lib_ring_buffer_ctx *ctx,
1150                         struct lttng_channel *chan),
1151                 void (*get_value)(struct lttng_ctx_field *field,
1152                         struct lttng_ctx_value *value))
1153 {
1154         struct lttng_session *session;
1155
1156         cds_list_for_each_entry(session, &sessions, node) {
1157                 struct lttng_channel *chan;
1158                 struct lttng_event *event;
1159                 int ret;
1160
1161                 ret = lttng_ust_context_set_provider_rcu(&session->ctx,
1162                                 name, get_size, record, get_value);
1163                 if (ret)
1164                         abort();
1165                 cds_list_for_each_entry(chan, &session->chan_head, node) {
1166                         ret = lttng_ust_context_set_provider_rcu(&chan->ctx,
1167                                         name, get_size, record, get_value);
1168                         if (ret)
1169                                 abort();
1170                 }
1171                 cds_list_for_each_entry(event, &session->events_head, node) {
1172                         ret = lttng_ust_context_set_provider_rcu(&event->ctx,
1173                                         name, get_size, record, get_value);
1174                         if (ret)
1175                                 abort();
1176                 }
1177         }
1178 }