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 #include <stdio.h>
  25 #include <urcu/list.h>
  26 #include <urcu/hlist.h>
  27 #include <pthread.h>
  28 #include <errno.h>
  29 #include <sys/shm.h>
  30 #include <sys/ipc.h>
  31 #include <stdint.h>
  32 #include <stddef.h>
  33 #include <inttypes.h>
  34 #include <time.h>
  35 #include <lttng/ust-endian.h>
  36 #include "clock.h"
  37
  38 #include <urcu-bp.h>
  39 #include <urcu/compiler.h>
  40 #include <urcu/uatomic.h>
  41 #include <urcu/arch.h>
  42
  43 #include <lttng/tracepoint.h>
  44 #include <lttng/ust-events.h>
  45
  46 #include <usterr-signal-safe.h>
  47 #include <helper.h>
  48 #include <lttng/ust-ctl.h>
  49 #include <ust-comm.h>
  50 #include "error.h"
  51 #include "compat.h"
  52 #include "lttng-ust-uuid.h"
  53
  54 #include "tracepoint-internal.h"
  55 #include "lttng-tracer.h"
  56 #include "lttng-tracer-core.h"
  57 #include "lttng-ust-statedump.h"
  58 #include "wait.h"
  59 #include "../libringbuffer/shm.h"
  60 #include "jhash.h"
  61
  62 /*
  63  * All operations within this file are called by the communication
  64  * thread, under ust_lock protection.
  65  */
  66
  67 static CDS_LIST_HEAD(sessions);
  68
  69 struct cds_list_head *_lttng_get_sessions(void)
  70 {
  71         return &sessions;
  72 }
  73
  74 static void _lttng_event_destroy(struct lttng_event *event);
  75 static void _lttng_enum_destroy(struct lttng_enum *_enum);
  76
  77 static
  78 void lttng_session_lazy_sync_enablers(struct lttng_session *session);
  79 static
  80 void lttng_session_sync_enablers(struct lttng_session *session);
  81 static
  82 void lttng_enabler_destroy(struct lttng_enabler *enabler);
  83
  84 /*
  85  * Called with ust lock held.
  86  */
  87 int lttng_session_active(void)
  88 {
  89         struct lttng_session *iter;
  90
  91         cds_list_for_each_entry(iter, &sessions, node) {
  92                 if (iter->active)
  93                         return 1;
  94         }
  95         return 0;
  96 }
  97
  98 static
  99 int lttng_loglevel_match(int loglevel,
 100                 unsigned int has_loglevel,
 101                 enum lttng_ust_loglevel_type req_type,
 102                 int req_loglevel)
 103 {
 104         if (!has_loglevel)
 105                 loglevel = TRACE_DEFAULT;
 106         switch (req_type) {
 107         case LTTNG_UST_LOGLEVEL_RANGE:
 108                 if (loglevel <= req_loglevel
 109                                 || (req_loglevel == -1 && loglevel <= TRACE_DEBUG))
 110                         return 1;
 111                 else
 112                         return 0;
 113         case LTTNG_UST_LOGLEVEL_SINGLE:
 114                 if (loglevel == req_loglevel
 115                                 || (req_loglevel == -1 && loglevel <= TRACE_DEBUG))
 116                         return 1;
 117                 else
 118                         return 0;
 119         case LTTNG_UST_LOGLEVEL_ALL:
 120         default:
 121                 if (loglevel <= TRACE_DEBUG)
 122                         return 1;
 123                 else
 124                         return 0;
 125         }
 126 }
 127
 128 void synchronize_trace(void)
 129 {
 130         synchronize_rcu();
 131 }
 132
 133 struct lttng_session *lttng_session_create(void)
 134 {
 135         struct lttng_session *session;
 136         int i;
 137
 138         session = zmalloc(sizeof(struct lttng_session));
 139         if (!session)
 140                 return NULL;
 141         CDS_INIT_LIST_HEAD(&session->chan_head);
 142         CDS_INIT_LIST_HEAD(&session->events_head);
 143         CDS_INIT_LIST_HEAD(&session->enums_head);
 144         CDS_INIT_LIST_HEAD(&session->enablers_head);
 145         for (i = 0; i < LTTNG_UST_EVENT_HT_SIZE; i++)
 146                 CDS_INIT_HLIST_HEAD(&session->events_ht.table[i]);
 147         for (i = 0; i < LTTNG_UST_ENUM_HT_SIZE; i++)
 148                 CDS_INIT_HLIST_HEAD(&session->enums_ht.table[i]);
 149         cds_list_add(&session->node, &sessions);
 150         return session;
 151 }
 152
 153 /*
 154  * Only used internally at session destruction.
 155  */
 156 static
 157 void _lttng_channel_unmap(struct lttng_channel *lttng_chan)
 158 {
 159         struct channel *chan;
 160         struct lttng_ust_shm_handle *handle;
 161
 162         cds_list_del(&lttng_chan->node);
 163         lttng_destroy_context(lttng_chan->ctx);
 164         chan = lttng_chan->chan;
 165         handle = lttng_chan->handle;
 166         /*
 167          * note: lttng_chan is private data contained within handle. It
 168          * will be freed along with the handle.
 169          */
 170         channel_destroy(chan, handle, 0);
 171 }
 172
 173 static
 174 void register_event(struct lttng_event *event)
 175 {
 176         int ret;
 177         const struct lttng_event_desc *desc;
 178
 179         assert(event->registered == 0);
 180         desc = event->desc;
 181         ret = __tracepoint_probe_register(desc->name,
 182                         desc->probe_callback,
 183                         event, desc->signature);
 184         WARN_ON_ONCE(ret);
 185         if (!ret)
 186                 event->registered = 1;
 187 }
 188
 189 static
 190 void unregister_event(struct lttng_event *event)
 191 {
 192         int ret;
 193         const struct lttng_event_desc *desc;
 194
 195         assert(event->registered == 1);
 196         desc = event->desc;
 197         ret = __tracepoint_probe_unregister(desc->name,
 198                         desc->probe_callback,
 199                         event);
 200         WARN_ON_ONCE(ret);
 201         if (!ret)
 202                 event->registered = 0;
 203 }
 204
 205 /*
 206  * Only used internally at session destruction.
 207  */
 208 static
 209 void _lttng_event_unregister(struct lttng_event *event)
 210 {
 211         if (event->registered)
 212                 unregister_event(event);
 213 }
 214
 215 void lttng_session_destroy(struct lttng_session *session)
 216 {
 217         struct lttng_channel *chan, *tmpchan;
 218         struct lttng_event *event, *tmpevent;
 219         struct lttng_enum *_enum, *tmp_enum;
 220         struct lttng_enabler *enabler, *tmpenabler;
 221
 222         CMM_ACCESS_ONCE(session->active) = 0;
 223         cds_list_for_each_entry(event, &session->events_head, node) {
 224                 _lttng_event_unregister(event);
 225         }
 226         synchronize_trace();    /* Wait for in-flight events to complete */
 227         cds_list_for_each_entry_safe(enabler, tmpenabler,
 228                         &session->enablers_head, node)
 229                 lttng_enabler_destroy(enabler);
 230         cds_list_for_each_entry_safe(event, tmpevent,
 231                         &session->events_head, node)
 232                 _lttng_event_destroy(event);
 233         cds_list_for_each_entry_safe(_enum, tmp_enum,
 234                         &session->enums_head, node)
 235                 _lttng_enum_destroy(_enum);
 236         cds_list_for_each_entry_safe(chan, tmpchan, &session->chan_head, node)
 237                 _lttng_channel_unmap(chan);
 238         cds_list_del(&session->node);
 239         free(session);
 240 }
 241
 242 int lttng_session_enable(struct lttng_session *session)
 243 {
 244         int ret = 0;
 245         struct lttng_channel *chan;
 246         int notify_socket;
 247
 248         if (session->active) {
 249                 ret = -EBUSY;
 250                 goto end;
 251         }
 252
 253         notify_socket = lttng_get_notify_socket(session->owner);
 254         if (notify_socket < 0)
 255                 return notify_socket;
 256
 257         /* Set transient enabler state to "enabled" */
 258         session->tstate = 1;
 259
 260         /*
 261          * Snapshot the number of events per channel to know the type of header
 262          * we need to use.
 263          */
 264         cds_list_for_each_entry(chan, &session->chan_head, node) {
 265                 const struct lttng_ctx *ctx;
 266                 const struct lttng_ctx_field *fields = NULL;
 267                 size_t nr_fields = 0;
 268                 uint32_t chan_id;
 269
 270                 /* don't change it if session stop/restart */
 271                 if (chan->header_type)
 272                         continue;
 273                 ctx = chan->ctx;
 274                 if (ctx) {
 275                         nr_fields = ctx->nr_fields;
 276                         fields = ctx->fields;
 277                 }
 278                 ret = ustcomm_register_channel(notify_socket,
 279                         session->objd,
 280                         chan->objd,
 281                         nr_fields,
 282                         fields,
 283                         &chan_id,
 284                         &chan->header_type);
 285                 if (ret) {
 286                         DBG("Error (%d) registering channel to sessiond", ret);
 287                         return ret;
 288                 }
 289                 if (chan_id != chan->id) {
 290                         DBG("Error: channel registration id (%u) does not match id assigned at creation (%u)",
 291                                 chan_id, chan->id);
 292                         return -EINVAL;
 293                 }
 294         }
 295
 296         /* We need to sync enablers with session before activation. */
 297         lttng_session_sync_enablers(session);
 298
 299         /* Set atomically the state to "active" */
 300         CMM_ACCESS_ONCE(session->active) = 1;
 301         CMM_ACCESS_ONCE(session->been_active) = 1;
 302
 303         session->statedump_pending = 1;
 304         lttng_ust_sockinfo_session_enabled(session->owner);
 305 end:
 306         return ret;
 307 }
 308
 309 int lttng_session_disable(struct lttng_session *session)
 310 {
 311         int ret = 0;
 312
 313         if (!session->active) {
 314                 ret = -EBUSY;
 315                 goto end;
 316         }
 317         /* Set atomically the state to "inactive" */
 318         CMM_ACCESS_ONCE(session->active) = 0;
 319
 320         /* Set transient enabler state to "disabled" */
 321         session->tstate = 0;
 322         lttng_session_sync_enablers(session);
 323 end:
 324         return ret;
 325 }
 326
 327 int lttng_channel_enable(struct lttng_channel *channel)
 328 {
 329         int ret = 0;
 330
 331         if (channel->enabled) {
 332                 ret = -EBUSY;
 333                 goto end;
 334         }
 335         /* Set transient enabler state to "enabled" */
 336         channel->tstate = 1;
 337         lttng_session_sync_enablers(channel->session);
 338         /* Set atomically the state to "enabled" */
 339         CMM_ACCESS_ONCE(channel->enabled) = 1;
 340 end:
 341         return ret;
 342 }
 343
 344 int lttng_channel_disable(struct lttng_channel *channel)
 345 {
 346         int ret = 0;
 347
 348         if (!channel->enabled) {
 349                 ret = -EBUSY;
 350                 goto end;
 351         }
 352         /* Set atomically the state to "disabled" */
 353         CMM_ACCESS_ONCE(channel->enabled) = 0;
 354         /* Set transient enabler state to "enabled" */
 355         channel->tstate = 0;
 356         lttng_session_sync_enablers(channel->session);
 357 end:
 358         return ret;
 359 }
 360
 361 static
 362 int lttng_enum_create(const struct lttng_enum_desc *desc,
 363                 struct lttng_session *session)
 364 {
 365         const char *enum_name = desc->name;
 366         struct lttng_enum *_enum;
 367         struct cds_hlist_head *head;
 368         struct cds_hlist_node *node;
 369         int ret = 0;
 370         size_t name_len = strlen(enum_name);
 371         uint32_t hash;
 372         int notify_socket;
 373
 374         hash = jhash(enum_name, name_len, 0);
 375         head = &session->enums_ht.table[hash & (LTTNG_UST_ENUM_HT_SIZE - 1)];
 376         cds_hlist_for_each_entry(_enum, node, head, hlist) {
 377                 assert(_enum->desc);
 378                 if (!strncmp(_enum->desc->name, desc->name,
 379                                 LTTNG_UST_SYM_NAME_LEN - 1)) {
 380                         ret = -EEXIST;
 381                         goto exist;
 382                 }
 383         }
 384
 385         notify_socket = lttng_get_notify_socket(session->owner);
 386         if (notify_socket < 0) {
 387                 ret = notify_socket;
 388                 goto socket_error;
 389         }
 390
 391         _enum = zmalloc(sizeof(*_enum));
 392         if (!_enum) {
 393                 ret = -ENOMEM;
 394                 goto cache_error;
 395         }
 396         _enum->session = session;
 397         _enum->desc = desc;
 398
 399         ret = ustcomm_register_enum(notify_socket,
 400                 session->objd,
 401                 enum_name,
 402                 desc->nr_entries,
 403                 desc->entries,
 404                 &_enum->id);
 405         if (ret < 0) {
 406                 DBG("Error (%d) registering enumeration to sessiond", ret);
 407                 goto sessiond_register_error;
 408         }
 409         cds_list_add(&_enum->node, &session->enums_head);
 410         cds_hlist_add_head(&_enum->hlist, head);
 411         return 0;
 412
 413 sessiond_register_error:
 414         free(_enum);
 415 cache_error:
 416 socket_error:
 417 exist:
 418         return ret;
 419 }
 420
 421 static
 422 int lttng_event_create_all_enums(const struct lttng_event_desc *desc,
 423                 struct lttng_session *session)
 424 {
 425         unsigned int nr_fields, i;
 426         const struct lttng_event_field *fields;
 427
 428         /* For each field, ensure enum is part of the session. */
 429         nr_fields = desc->nr_fields;
 430         fields = desc->fields;
 431         for (i = 0; i < nr_fields; i++) {
 432                 const struct lttng_type *type = &fields[i].type;
 433
 434                 switch (type->atype) {
 435                 case atype_enum:
 436                 {
 437                         const struct lttng_enum_desc *enum_desc;
 438                         int ret;
 439
 440                         enum_desc = type->u.basic.enumeration.desc;
 441                         ret = lttng_enum_create(enum_desc, session);
 442                         if (ret && ret != -EEXIST) {
 443                                 DBG("Unable to create enum error: (%d)", ret);
 444                                 return ret;
 445                         }
 446                         break;
 447                 }
 448                 default:
 449                         /* TODO: nested types when they become supported. */
 450                         continue;
 451                 }
 452         }
 453         return 0;
 454 }
 455
 456 /*
 457  * Supports event creation while tracing session is active.
 458  */
 459 static
 460 int lttng_event_create(const struct lttng_event_desc *desc,
 461                 struct lttng_channel *chan)
 462 {
 463         const char *event_name = desc->name;
 464         struct lttng_event *event;
 465         struct lttng_session *session = chan->session;
 466         struct cds_hlist_head *head;
 467         struct cds_hlist_node *node;
 468         int ret = 0;
 469         size_t name_len = strlen(event_name);
 470         uint32_t hash;
 471         int notify_socket, loglevel;
 472         const char *uri;
 473
 474         hash = jhash(event_name, name_len, 0);
 475         head = &chan->session->events_ht.table[hash & (LTTNG_UST_EVENT_HT_SIZE - 1)];
 476         cds_hlist_for_each_entry(event, node, head, hlist) {
 477                 assert(event->desc);
 478                 if (!strncmp(event->desc->name, desc->name,
 479                                         LTTNG_UST_SYM_NAME_LEN - 1)
 480                                 && chan == event->chan) {
 481                         ret = -EEXIST;
 482                         goto exist;
 483                 }
 484         }
 485
 486         notify_socket = lttng_get_notify_socket(session->owner);
 487         if (notify_socket < 0) {
 488                 ret = notify_socket;
 489                 goto socket_error;
 490         }
 491
 492         ret = lttng_event_create_all_enums(desc, session);
 493         if (ret < 0) {
 494                 DBG("Error (%d) adding enum to session", ret);
 495                 goto create_enum_error;
 496         }
 497
 498         /*
 499          * Check if loglevel match. Refuse to connect event if not.
 500          */
 501         event = zmalloc(sizeof(struct lttng_event));
 502         if (!event) {
 503                 ret = -ENOMEM;
 504                 goto cache_error;
 505         }
 506         event->chan = chan;
 507
 508         /* Event will be enabled by enabler sync. */
 509         event->enabled = 0;
 510         event->registered = 0;
 511         CDS_INIT_LIST_HEAD(&event->bytecode_runtime_head);
 512         CDS_INIT_LIST_HEAD(&event->enablers_ref_head);
 513         event->desc = desc;
 514
 515         if (desc->loglevel)
 516                 loglevel = *(*event->desc->loglevel);
 517         else
 518                 loglevel = TRACE_DEFAULT;
 519         if (desc->u.ext.model_emf_uri)
 520                 uri = *(desc->u.ext.model_emf_uri);
 521         else
 522                 uri = NULL;
 523
 524         /* Fetch event ID from sessiond */
 525         ret = ustcomm_register_event(notify_socket,
 526                 session,
 527                 session->objd,
 528                 chan->objd,
 529                 event_name,
 530                 loglevel,
 531                 desc->signature,
 532                 desc->nr_fields,
 533                 desc->fields,
 534                 uri,
 535                 &event->id);
 536         if (ret < 0) {
 537                 DBG("Error (%d) registering event to sessiond", ret);
 538                 goto sessiond_register_error;
 539         }
 540
 541         /* Populate lttng_event structure before tracepoint registration. */
 542         cmm_smp_wmb();
 543         cds_list_add(&event->node, &chan->session->events_head);
 544         cds_hlist_add_head(&event->hlist, head);
 545         return 0;
 546
 547 sessiond_register_error:
 548         free(event);
 549 cache_error:
 550 create_enum_error:
 551 socket_error:
 552 exist:
 553         return ret;
 554 }
 555
 556 static
 557 int lttng_desc_match_wildcard_enabler(const struct lttng_event_desc *desc,
 558                 struct lttng_enabler *enabler)
 559 {
 560         int loglevel = 0;
 561         unsigned int has_loglevel = 0;
 562
 563         assert(enabler->type == LTTNG_ENABLER_WILDCARD);
 564         /* Compare excluding final '*' */
 565         if (strncmp(desc->name, enabler->event_param.name,
 566                         strlen(enabler->event_param.name) - 1))
 567                 return 0;
 568         if (desc->loglevel) {
 569                 loglevel = *(*desc->loglevel);
 570                 has_loglevel = 1;
 571         }
 572         if (!lttng_loglevel_match(loglevel,
 573                         has_loglevel,
 574                         enabler->event_param.loglevel_type,
 575                         enabler->event_param.loglevel))
 576                 return 0;
 577         return 1;
 578 }
 579
 580 static
 581 int lttng_desc_match_event_enabler(const struct lttng_event_desc *desc,
 582                 struct lttng_enabler *enabler)
 583 {
 584         int loglevel = 0;
 585         unsigned int has_loglevel = 0;
 586
 587         assert(enabler->type == LTTNG_ENABLER_EVENT);
 588         if (strcmp(desc->name, enabler->event_param.name))
 589                 return 0;
 590         if (desc->loglevel) {
 591                 loglevel = *(*desc->loglevel);
 592                 has_loglevel = 1;
 593         }
 594         if (!lttng_loglevel_match(loglevel,
 595                         has_loglevel,
 596                         enabler->event_param.loglevel_type,
 597                         enabler->event_param.loglevel))
 598                 return 0;
 599         return 1;
 600 }
 601
 602 static
 603 int lttng_desc_match_enabler(const struct lttng_event_desc *desc,
 604                 struct lttng_enabler *enabler)
 605 {
 606         struct lttng_ust_excluder_node *excluder;
 607
 608         /* If event matches with an excluder, return 'does not match' */
 609         cds_list_for_each_entry(excluder, &enabler->excluder_head, node) {
 610                 int count;
 611
 612                 for (count = 0; count < excluder->excluder.count; count++) {
 613                         int found, len;
 614                         char *excluder_name;
 615
 616                         excluder_name = (char *) (excluder->excluder.names)
 617                                         + count * LTTNG_UST_SYM_NAME_LEN;
 618                         len = strnlen(excluder_name, LTTNG_UST_SYM_NAME_LEN);
 619                         if (len > 0 && excluder_name[len - 1] == '*') {
 620                                 found = !strncmp(desc->name, excluder_name,
 621                                                 len - 1);
 622                         } else {
 623                                 found = !strncmp(desc->name, excluder_name,
 624                                                 LTTNG_UST_SYM_NAME_LEN - 1);
 625                         }
 626                         if (found) {
 627                                 return 0;
 628                         }
 629                 }
 630         }
 631         switch (enabler->type) {
 632         case LTTNG_ENABLER_WILDCARD:
 633                 return lttng_desc_match_wildcard_enabler(desc, enabler);
 634         case LTTNG_ENABLER_EVENT:
 635                 return lttng_desc_match_event_enabler(desc, enabler);
 636         default:
 637                 return -EINVAL;
 638         }
 639 }
 640
 641 static
 642 int lttng_event_match_enabler(struct lttng_event *event,
 643                 struct lttng_enabler *enabler)
 644 {
 645         if (lttng_desc_match_enabler(event->desc, enabler)
 646                         && event->chan == enabler->chan)
 647                 return 1;
 648         else
 649                 return 0;
 650 }
 651
 652 static
 653 struct lttng_enabler_ref * lttng_event_enabler_ref(struct lttng_event *event,
 654                 struct lttng_enabler *enabler)
 655 {
 656         struct lttng_enabler_ref *enabler_ref;
 657
 658         cds_list_for_each_entry(enabler_ref,
 659                         &event->enablers_ref_head, node) {
 660                 if (enabler_ref->ref == enabler)
 661                         return enabler_ref;
 662         }
 663         return NULL;
 664 }
 665
 666 /*
 667  * Create struct lttng_event if it is missing and present in the list of
 668  * tracepoint probes.
 669  */
 670 static
 671 void lttng_create_event_if_missing(struct lttng_enabler *enabler)
 672 {
 673         struct lttng_session *session = enabler->chan->session;
 674         struct lttng_probe_desc *probe_desc;
 675         const struct lttng_event_desc *desc;
 676         struct lttng_event *event;
 677         int i;
 678         struct cds_list_head *probe_list;
 679
 680         probe_list = lttng_get_probe_list_head();
 681         /*
 682          * For each probe event, if we find that a probe event matches
 683          * our enabler, create an associated lttng_event if not
 684          * already present.
 685          */
 686         cds_list_for_each_entry(probe_desc, probe_list, head) {
 687                 for (i = 0; i < probe_desc->nr_events; i++) {
 688                         int found = 0, ret;
 689                         struct cds_hlist_head *head;
 690                         struct cds_hlist_node *node;
 691                         const char *event_name;
 692                         size_t name_len;
 693                         uint32_t hash;
 694
 695                         desc = probe_desc->event_desc[i];
 696                         if (!lttng_desc_match_enabler(desc, enabler))
 697                                 continue;
 698                         event_name = desc->name;
 699                         name_len = strlen(event_name);
 700
 701                         /*
 702                          * Check if already created.
 703                          */
 704                         hash = jhash(event_name, name_len, 0);
 705                         head = &session->events_ht.table[hash & (LTTNG_UST_EVENT_HT_SIZE - 1)];
 706                         cds_hlist_for_each_entry(event, node, head, hlist) {
 707                                 if (event->desc == desc
 708                                                 && event->chan == enabler->chan)
 709                                         found = 1;
 710                         }
 711                         if (found)
 712                                 continue;
 713
 714                         /*
 715                          * We need to create an event for this
 716                          * event probe.
 717                          */
 718                         ret = lttng_event_create(probe_desc->event_desc[i],
 719                                         enabler->chan);
 720                         if (ret) {
 721                                 DBG("Unable to create event %s, error %d\n",
 722                                         probe_desc->event_desc[i]->name, ret);
 723                         }
 724                 }
 725         }
 726 }
 727
 728 /*
 729  * Create events associated with an enabler (if not already present),
 730  * and add backward reference from the event to the enabler.
 731  */
 732 static
 733 int lttng_enabler_ref_events(struct lttng_enabler *enabler)
 734 {
 735         struct lttng_session *session = enabler->chan->session;
 736         struct lttng_event *event;
 737
 738         /* First ensure that probe events are created for this enabler. */
 739         lttng_create_event_if_missing(enabler);
 740
 741         /* For each event matching enabler in session event list. */
 742         cds_list_for_each_entry(event, &session->events_head, node) {
 743                 struct lttng_enabler_ref *enabler_ref;
 744
 745                 if (!lttng_event_match_enabler(event, enabler))
 746                         continue;
 747
 748                 enabler_ref = lttng_event_enabler_ref(event, enabler);
 749                 if (!enabler_ref) {
 750                         /*
 751                          * If no backward ref, create it.
 752                          * Add backward ref from event to enabler.
 753                          */
 754                         enabler_ref = zmalloc(sizeof(*enabler_ref));
 755                         if (!enabler_ref)
 756                                 return -ENOMEM;
 757                         enabler_ref->ref = enabler;
 758                         cds_list_add(&enabler_ref->node,
 759                                 &event->enablers_ref_head);
 760                 }
 761
 762                 /*
 763                  * Link filter bytecodes if not linked yet.
 764                  */
 765                 lttng_enabler_event_link_bytecode(event, enabler);
 766
 767                 /* TODO: merge event context. */
 768         }
 769         return 0;
 770 }
 771
 772 /*
 773  * Called at library load: connect the probe on all enablers matching
 774  * this event.
 775  * Called with session mutex held.
 776  */
 777 int lttng_fix_pending_events(void)
 778 {
 779         struct lttng_session *session;
 780
 781         cds_list_for_each_entry(session, &sessions, node) {
 782                 lttng_session_lazy_sync_enablers(session);
 783         }
 784         return 0;
 785 }
 786
 787 /*
 788  * For each session of the owner thread, execute pending statedump.
 789  * Only dump state for the sessions owned by the caller thread, because
 790  * we don't keep ust_lock across the entire iteration.
 791  */
 792 void lttng_handle_pending_statedump(void *owner)
 793 {
 794         struct lttng_session *session;
 795
 796         /* Execute state dump */
 797         do_lttng_ust_statedump(owner);
 798
 799         /* Clear pending state dump */
 800         if (ust_lock()) {
 801                 goto end;
 802         }
 803         cds_list_for_each_entry(session, &sessions, node) {
 804                 if (session->owner != owner)
 805                         continue;
 806                 if (!session->statedump_pending)
 807                         continue;
 808                 session->statedump_pending = 0;
 809         }
 810 end:
 811         ust_unlock();
 812         return;
 813 }
 814
 815 /*
 816  * Only used internally at session destruction.
 817  */
 818 static
 819 void _lttng_event_destroy(struct lttng_event *event)
 820 {
 821         struct lttng_enabler_ref *enabler_ref, *tmp_enabler_ref;
 822
 823         cds_list_del(&event->node);
 824         lttng_destroy_context(event->ctx);
 825         lttng_free_event_filter_runtime(event);
 826         /* Free event enabler refs */
 827         cds_list_for_each_entry_safe(enabler_ref, tmp_enabler_ref,
 828                         &event->enablers_ref_head, node)
 829                 free(enabler_ref);
 830         free(event);
 831 }
 832
 833 static
 834 void _lttng_enum_destroy(struct lttng_enum *_enum)
 835 {
 836         cds_list_del(&_enum->node);
 837         free(_enum);
 838 }
 839
 840 void lttng_ust_events_exit(void)
 841 {
 842         struct lttng_session *session, *tmpsession;
 843
 844         cds_list_for_each_entry_safe(session, tmpsession, &sessions, node)
 845                 lttng_session_destroy(session);
 846 }
 847
 848 /*
 849  * Enabler management.
 850  */
 851 struct lttng_enabler *lttng_enabler_create(enum lttng_enabler_type type,
 852                 struct lttng_ust_event *event_param,
 853                 struct lttng_channel *chan)
 854 {
 855         struct lttng_enabler *enabler;
 856
 857         enabler = zmalloc(sizeof(*enabler));
 858         if (!enabler)
 859                 return NULL;
 860         enabler->type = type;
 861         CDS_INIT_LIST_HEAD(&enabler->filter_bytecode_head);
 862         CDS_INIT_LIST_HEAD(&enabler->excluder_head);
 863         memcpy(&enabler->event_param, event_param,
 864                 sizeof(enabler->event_param));
 865         enabler->chan = chan;
 866         /* ctx left NULL */
 867         enabler->enabled = 0;
 868         cds_list_add(&enabler->node, &enabler->chan->session->enablers_head);
 869         lttng_session_lazy_sync_enablers(enabler->chan->session);
 870         return enabler;
 871 }
 872
 873 int lttng_enabler_enable(struct lttng_enabler *enabler)
 874 {
 875         enabler->enabled = 1;
 876         lttng_session_lazy_sync_enablers(enabler->chan->session);
 877         return 0;
 878 }
 879
 880 int lttng_enabler_disable(struct lttng_enabler *enabler)
 881 {
 882         enabler->enabled = 0;
 883         lttng_session_lazy_sync_enablers(enabler->chan->session);
 884         return 0;
 885 }
 886
 887 int lttng_enabler_attach_bytecode(struct lttng_enabler *enabler,
 888                 struct lttng_ust_filter_bytecode_node *bytecode)
 889 {
 890         bytecode->enabler = enabler;
 891         cds_list_add_tail(&bytecode->node, &enabler->filter_bytecode_head);
 892         lttng_session_lazy_sync_enablers(enabler->chan->session);
 893         return 0;
 894 }
 895
 896 int lttng_enabler_attach_exclusion(struct lttng_enabler *enabler,
 897                 struct lttng_ust_excluder_node *excluder)
 898 {
 899         excluder->enabler = enabler;
 900         cds_list_add_tail(&excluder->node, &enabler->excluder_head);
 901         lttng_session_lazy_sync_enablers(enabler->chan->session);
 902         return 0;
 903 }
 904
 905 int lttng_attach_context(struct lttng_ust_context *context_param,
 906                 struct lttng_ctx **ctx, struct lttng_session *session)
 907 {
 908         /*
 909          * We cannot attach a context after trace has been started for a
 910          * session because the metadata does not allow expressing this
 911          * information outside of the original channel scope.
 912          */
 913         if (session->been_active)
 914                 return -EPERM;
 915
 916         switch (context_param->ctx) {
 917         case LTTNG_UST_CONTEXT_PTHREAD_ID:
 918                 return lttng_add_pthread_id_to_ctx(ctx);
 919         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
 920         {
 921                 struct lttng_ust_perf_counter_ctx *perf_ctx_param;
 922
 923                 perf_ctx_param = &context_param->u.perf_counter;
 924                 return lttng_add_perf_counter_to_ctx(
 925                         perf_ctx_param->type,
 926                         perf_ctx_param->config,
 927                         perf_ctx_param->name,
 928                         ctx);
 929         }
 930         case LTTNG_UST_CONTEXT_VTID:
 931                 return lttng_add_vtid_to_ctx(ctx);
 932         case LTTNG_UST_CONTEXT_VPID:
 933                 return lttng_add_vpid_to_ctx(ctx);
 934         case LTTNG_UST_CONTEXT_PROCNAME:
 935                 return lttng_add_procname_to_ctx(ctx);
 936         case LTTNG_UST_CONTEXT_IP:
 937                 return lttng_add_ip_to_ctx(ctx);
 938         case LTTNG_UST_CONTEXT_CPU_ID:
 939                 return lttng_add_cpu_id_to_ctx(ctx);
 940         default:
 941                 return -EINVAL;
 942         }
 943 }
 944
 945 int lttng_enabler_attach_context(struct lttng_enabler *enabler,
 946                 struct lttng_ust_context *context_param)
 947 {
 948 #if 0   // disabled for now.
 949         struct lttng_session *session = enabler->chan->session;
 950         int ret;
 951
 952         ret = lttng_attach_context(context_param, &enabler->ctx,
 953                         session);
 954         if (ret)
 955                 return ret;
 956         lttng_session_lazy_sync_enablers(enabler->chan->session);
 957 #endif
 958         return -ENOSYS;
 959 }
 960
 961 static
 962 void lttng_enabler_destroy(struct lttng_enabler *enabler)
 963 {
 964         struct lttng_ust_filter_bytecode_node *filter_node, *tmp_filter_node;
 965         struct lttng_ust_excluder_node *excluder_node, *tmp_excluder_node;
 966
 967         /* Destroy filter bytecode */
 968         cds_list_for_each_entry_safe(filter_node, tmp_filter_node,
 969                         &enabler->filter_bytecode_head, node) {
 970                 free(filter_node);
 971         }
 972
 973         /* Destroy excluders */
 974         cds_list_for_each_entry_safe(excluder_node, tmp_excluder_node,
 975                         &enabler->excluder_head, node) {
 976                 free(excluder_node);
 977         }
 978
 979         /* Destroy contexts */
 980         lttng_destroy_context(enabler->ctx);
 981
 982         cds_list_del(&enabler->node);
 983         free(enabler);
 984 }
 985
 986 /*
 987  * lttng_session_sync_enablers should be called just before starting a
 988  * session.
 989  */
 990 static
 991 void lttng_session_sync_enablers(struct lttng_session *session)
 992 {
 993         struct lttng_enabler *enabler;
 994         struct lttng_event *event;
 995
 996         cds_list_for_each_entry(enabler, &session->enablers_head, node)
 997                 lttng_enabler_ref_events(enabler);
 998         /*
 999          * For each event, if at least one of its enablers is enabled,
1000          * and its channel and session transient states are enabled, we
1001          * enable the event, else we disable it.
1002          */
1003         cds_list_for_each_entry(event, &session->events_head, node) {
1004                 struct lttng_enabler_ref *enabler_ref;
1005                 struct lttng_bytecode_runtime *runtime;
1006                 int enabled = 0, has_enablers_without_bytecode = 0;
1007
1008                 /* Enable events */
1009                 cds_list_for_each_entry(enabler_ref,
1010                                 &event->enablers_ref_head, node) {
1011                         if (enabler_ref->ref->enabled) {
1012                                 enabled = 1;
1013                                 break;
1014                         }
1015                 }
1016                 /*
1017                  * Enabled state is based on union of enablers, with
1018                  * intesection of session and channel transient enable
1019                  * states.
1020                  */
1021                 enabled = enabled && session->tstate && event->chan->tstate;
1022
1023                 CMM_STORE_SHARED(event->enabled, enabled);
1024                 /*
1025                  * Sync tracepoint registration with event enabled
1026                  * state.
1027                  */
1028                 if (enabled) {
1029                         if (!event->registered)
1030                                 register_event(event);
1031                 } else {
1032                         if (event->registered)
1033                                 unregister_event(event);
1034                 }
1035
1036                 /* Check if has enablers without bytecode enabled */
1037                 cds_list_for_each_entry(enabler_ref,
1038                                 &event->enablers_ref_head, node) {
1039                         if (enabler_ref->ref->enabled
1040                                         && cds_list_empty(&enabler_ref->ref->filter_bytecode_head)) {
1041                                 has_enablers_without_bytecode = 1;
1042                                 break;
1043                         }
1044                 }
1045                 event->has_enablers_without_bytecode =
1046                         has_enablers_without_bytecode;
1047
1048                 /* Enable filters */
1049                 cds_list_for_each_entry(runtime,
1050                                 &event->bytecode_runtime_head, node) {
1051                         lttng_filter_sync_state(runtime);
1052                 }
1053         }
1054 }
1055
1056 /*
1057  * Apply enablers to session events, adding events to session if need
1058  * be. It is required after each modification applied to an active
1059  * session, and right before session "start".
1060  * "lazy" sync means we only sync if required.
1061  */
1062 static
1063 void lttng_session_lazy_sync_enablers(struct lttng_session *session)
1064 {
1065         /* We can skip if session is not active */
1066         if (!session->active)
1067                 return;
1068         lttng_session_sync_enablers(session);
1069 }