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 "wait.h"
  58 #include "../libringbuffer/shm.h"
  59 #include "jhash.h"
  60
  61 /*
  62  * The sessions mutex is the centralized mutex across UST tracing
  63  * control and probe registration. All operations within this file are
  64  * called by the communication thread, under ust_lock protection.
  65  */
  66 static pthread_mutex_t sessions_mutex = PTHREAD_MUTEX_INITIALIZER;
  67
  68 void ust_lock(void)
  69 {
  70         pthread_mutex_lock(&sessions_mutex);
  71 }
  72
  73 void ust_unlock(void)
  74 {
  75         pthread_mutex_unlock(&sessions_mutex);
  76 }
  77
  78 static CDS_LIST_HEAD(sessions);
  79
  80 static void _lttng_event_destroy(struct lttng_event *event);
  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 || req_loglevel == -1)
 114                         return 1;
 115                 else
 116                         return 0;
 117         case LTTNG_UST_LOGLEVEL_SINGLE:
 118                 if (loglevel == req_loglevel || req_loglevel == -1)
 119                         return 1;
 120                 else
 121                         return 0;
 122         case LTTNG_UST_LOGLEVEL_ALL:
 123         default:
 124                 return 1;
 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->enablers_head);
 144         for (i = 0; i < LTTNG_UST_EVENT_HT_SIZE; i++)
 145                 CDS_INIT_HLIST_HEAD(&session->events_ht.table[i]);
 146         cds_list_add(&session->node, &sessions);
 147         return session;
 148 }
 149
 150 /*
 151  * Only used internally at session destruction.
 152  */
 153 static
 154 void _lttng_channel_unmap(struct lttng_channel *lttng_chan)
 155 {
 156         struct channel *chan;
 157         struct lttng_ust_shm_handle *handle;
 158
 159         cds_list_del(&lttng_chan->node);
 160         lttng_destroy_context(lttng_chan->ctx);
 161         chan = lttng_chan->chan;
 162         handle = lttng_chan->handle;
 163         /*
 164          * note: lttng_chan is private data contained within handle. It
 165          * will be freed along with the handle.
 166          */
 167         channel_destroy(chan, handle, 0);
 168 }
 169
 170 static
 171 void register_event(struct lttng_event *event)
 172 {
 173         int ret;
 174         const struct lttng_event_desc *desc;
 175
 176         assert(event->registered == 0);
 177         desc = event->desc;
 178         ret = __tracepoint_probe_register(desc->name,
 179                         desc->probe_callback,
 180                         event, desc->signature);
 181         WARN_ON_ONCE(ret);
 182         if (!ret)
 183                 event->registered = 1;
 184 }
 185
 186 static
 187 void unregister_event(struct lttng_event *event)
 188 {
 189         int ret;
 190         const struct lttng_event_desc *desc;
 191
 192         assert(event->registered == 1);
 193         desc = event->desc;
 194         ret = __tracepoint_probe_unregister(desc->name,
 195                         desc->probe_callback,
 196                         event);
 197         WARN_ON_ONCE(ret);
 198         if (!ret)
 199                 event->registered = 0;
 200 }
 201
 202 /*
 203  * Only used internally at session destruction.
 204  */
 205 static
 206 void _lttng_event_unregister(struct lttng_event *event)
 207 {
 208         if (event->registered)
 209                 unregister_event(event);
 210 }
 211
 212 void lttng_session_destroy(struct lttng_session *session)
 213 {
 214         struct lttng_channel *chan, *tmpchan;
 215         struct lttng_event *event, *tmpevent;
 216         struct lttng_enabler *enabler, *tmpenabler;
 217
 218         CMM_ACCESS_ONCE(session->active) = 0;
 219         cds_list_for_each_entry(event, &session->events_head, node) {
 220                 _lttng_event_unregister(event);
 221         }
 222         synchronize_trace();    /* Wait for in-flight events to complete */
 223         cds_list_for_each_entry_safe(enabler, tmpenabler,
 224                         &session->enablers_head, node)
 225                 lttng_enabler_destroy(enabler);
 226         cds_list_for_each_entry_safe(event, tmpevent,
 227                         &session->events_head, node)
 228                 _lttng_event_destroy(event);
 229         cds_list_for_each_entry_safe(chan, tmpchan, &session->chan_head, node)
 230                 _lttng_channel_unmap(chan);
 231         cds_list_del(&session->node);
 232         free(session);
 233 }
 234
 235 int lttng_session_enable(struct lttng_session *session)
 236 {
 237         int ret = 0;
 238         struct lttng_channel *chan;
 239         int notify_socket;
 240
 241         if (session->active) {
 242                 ret = -EBUSY;
 243                 goto end;
 244         }
 245
 246         notify_socket = lttng_get_notify_socket(session->owner);
 247         if (notify_socket < 0)
 248                 return notify_socket;
 249
 250         /* Set transient enabler state to "enabled" */
 251         session->tstate = 1;
 252         /* We need to sync enablers with session before activation. */
 253         lttng_session_sync_enablers(session);
 254
 255         /*
 256          * Snapshot the number of events per channel to know the type of header
 257          * we need to use.
 258          */
 259         cds_list_for_each_entry(chan, &session->chan_head, node) {
 260                 const struct lttng_ctx *ctx;
 261                 const struct lttng_ctx_field *fields = NULL;
 262                 size_t nr_fields = 0;
 263                 uint32_t chan_id;
 264
 265                 /* don't change it if session stop/restart */
 266                 if (chan->header_type)
 267                         continue;
 268                 ctx = chan->ctx;
 269                 if (ctx) {
 270                         nr_fields = ctx->nr_fields;
 271                         fields = ctx->fields;
 272                 }
 273                 ret = ustcomm_register_channel(notify_socket,
 274                         session->objd,
 275                         chan->objd,
 276                         nr_fields,
 277                         fields,
 278                         &chan_id,
 279                         &chan->header_type);
 280                 if (ret) {
 281                         DBG("Error (%d) registering channel to sessiond", ret);
 282                         return ret;
 283                 }
 284                 if (chan_id != chan->id) {
 285                         DBG("Error: channel registration id (%u) does not match id assigned at creation (%u)",
 286                                 chan_id, chan->id);
 287                         return -EINVAL;
 288                 }
 289         }
 290
 291         /* Set atomically the state to "active" */
 292         CMM_ACCESS_ONCE(session->active) = 1;
 293         CMM_ACCESS_ONCE(session->been_active) = 1;
 294 end:
 295         return ret;
 296 }
 297
 298 int lttng_session_disable(struct lttng_session *session)
 299 {
 300         int ret = 0;
 301
 302         if (!session->active) {
 303                 ret = -EBUSY;
 304                 goto end;
 305         }
 306         /* Set atomically the state to "inactive" */
 307         CMM_ACCESS_ONCE(session->active) = 0;
 308
 309         /* Set transient enabler state to "disabled" */
 310         session->tstate = 0;
 311         lttng_session_sync_enablers(session);
 312 end:
 313         return ret;
 314 }
 315
 316 int lttng_channel_enable(struct lttng_channel *channel)
 317 {
 318         int ret = 0;
 319
 320         if (channel->enabled) {
 321                 ret = -EBUSY;
 322                 goto end;
 323         }
 324         /* Set transient enabler state to "enabled" */
 325         channel->tstate = 1;
 326         lttng_session_sync_enablers(channel->session);
 327         /* Set atomically the state to "enabled" */
 328         CMM_ACCESS_ONCE(channel->enabled) = 1;
 329 end:
 330         return ret;
 331 }
 332
 333 int lttng_channel_disable(struct lttng_channel *channel)
 334 {
 335         int ret = 0;
 336
 337         if (!channel->enabled) {
 338                 ret = -EBUSY;
 339                 goto end;
 340         }
 341         /* Set atomically the state to "disabled" */
 342         CMM_ACCESS_ONCE(channel->enabled) = 0;
 343         /* Set transient enabler state to "enabled" */
 344         channel->tstate = 0;
 345         lttng_session_sync_enablers(channel->session);
 346 end:
 347         return ret;
 348 }
 349
 350 /*
 351  * Supports event creation while tracing session is active.
 352  */
 353 static
 354 int lttng_event_create(const struct lttng_event_desc *desc,
 355                 struct lttng_channel *chan)
 356 {
 357         const char *event_name = desc->name;
 358         struct lttng_event *event;
 359         struct lttng_session *session = chan->session;
 360         struct cds_hlist_head *head;
 361         struct cds_hlist_node *node;
 362         int ret = 0;
 363         size_t name_len = strlen(event_name);
 364         uint32_t hash;
 365         int notify_socket, loglevel;
 366         const char *uri;
 367
 368         hash = jhash(event_name, name_len, 0);
 369         head = &chan->session->events_ht.table[hash & (LTTNG_UST_EVENT_HT_SIZE - 1)];
 370         cds_hlist_for_each_entry(event, node, head, hlist) {
 371                 assert(event->desc);
 372                 if (!strncmp(event->desc->name, desc->name,
 373                                         LTTNG_UST_SYM_NAME_LEN - 1)
 374                                 && chan == event->chan) {
 375                         ret = -EEXIST;
 376                         goto exist;
 377                 }
 378         }
 379
 380         notify_socket = lttng_get_notify_socket(session->owner);
 381         if (notify_socket < 0) {
 382                 ret = notify_socket;
 383                 goto socket_error;
 384         }
 385
 386         /*
 387          * Check if loglevel match. Refuse to connect event if not.
 388          */
 389         event = zmalloc(sizeof(struct lttng_event));
 390         if (!event) {
 391                 ret = -ENOMEM;
 392                 goto cache_error;
 393         }
 394         event->chan = chan;
 395
 396         /* Event will be enabled by enabler sync. */
 397         event->enabled = 0;
 398         event->registered = 0;
 399         CDS_INIT_LIST_HEAD(&event->bytecode_runtime_head);
 400         CDS_INIT_LIST_HEAD(&event->enablers_ref_head);
 401         event->desc = desc;
 402
 403         if (desc->loglevel)
 404                 loglevel = *(*event->desc->loglevel);
 405         else
 406                 loglevel = TRACE_DEFAULT;
 407         if (desc->u.ext.model_emf_uri)
 408                 uri = *(desc->u.ext.model_emf_uri);
 409         else
 410                 uri = NULL;
 411
 412         /* Fetch event ID from sessiond */
 413         ret = ustcomm_register_event(notify_socket,
 414                 session->objd,
 415                 chan->objd,
 416                 event_name,
 417                 loglevel,
 418                 desc->signature,
 419                 desc->nr_fields,
 420                 desc->fields,
 421                 uri,
 422                 &event->id);
 423         if (ret < 0) {
 424                 DBG("Error (%d) registering event to sessiond", ret);
 425                 goto sessiond_register_error;
 426         }
 427
 428         /* Populate lttng_event structure before tracepoint registration. */
 429         cmm_smp_wmb();
 430         cds_list_add(&event->node, &chan->session->events_head);
 431         cds_hlist_add_head(&event->hlist, head);
 432         return 0;
 433
 434 sessiond_register_error:
 435         free(event);
 436 cache_error:
 437 socket_error:
 438 exist:
 439         return ret;
 440 }
 441
 442 static
 443 int lttng_desc_match_wildcard_enabler(const struct lttng_event_desc *desc,
 444                 struct lttng_enabler *enabler)
 445 {
 446         int loglevel = 0;
 447         unsigned int has_loglevel = 0;
 448
 449         assert(enabler->type == LTTNG_ENABLER_WILDCARD);
 450         /* Compare excluding final '*' */
 451         if (strncmp(desc->name, enabler->event_param.name,
 452                         strlen(enabler->event_param.name) - 1))
 453                 return 0;
 454         if (desc->loglevel) {
 455                 loglevel = *(*desc->loglevel);
 456                 has_loglevel = 1;
 457         }
 458         if (!lttng_loglevel_match(loglevel,
 459                         has_loglevel,
 460                         enabler->event_param.loglevel_type,
 461                         enabler->event_param.loglevel))
 462                 return 0;
 463         return 1;
 464 }
 465
 466 static
 467 int lttng_desc_match_event_enabler(const struct lttng_event_desc *desc,
 468                 struct lttng_enabler *enabler)
 469 {
 470         int loglevel = 0;
 471         unsigned int has_loglevel = 0;
 472
 473         assert(enabler->type == LTTNG_ENABLER_EVENT);
 474         if (strcmp(desc->name, enabler->event_param.name))
 475                 return 0;
 476         if (desc->loglevel) {
 477                 loglevel = *(*desc->loglevel);
 478                 has_loglevel = 1;
 479         }
 480         if (!lttng_loglevel_match(loglevel,
 481                         has_loglevel,
 482                         enabler->event_param.loglevel_type,
 483                         enabler->event_param.loglevel))
 484                 return 0;
 485         return 1;
 486 }
 487
 488 static
 489 int lttng_desc_match_enabler(const struct lttng_event_desc *desc,
 490                 struct lttng_enabler *enabler)
 491 {
 492         switch (enabler->type) {
 493         case LTTNG_ENABLER_WILDCARD:
 494                 return lttng_desc_match_wildcard_enabler(desc, enabler);
 495         case LTTNG_ENABLER_EVENT:
 496                 return lttng_desc_match_event_enabler(desc, enabler);
 497         default:
 498                 return -EINVAL;
 499         }
 500 }
 501
 502 static
 503 int lttng_event_match_enabler(struct lttng_event *event,
 504                 struct lttng_enabler *enabler)
 505 {
 506         if (lttng_desc_match_enabler(event->desc, enabler)
 507                         && event->chan == enabler->chan)
 508                 return 1;
 509         else
 510                 return 0;
 511 }
 512
 513 static
 514 struct lttng_enabler_ref * lttng_event_enabler_ref(struct lttng_event *event,
 515                 struct lttng_enabler *enabler)
 516 {
 517         struct lttng_enabler_ref *enabler_ref;
 518
 519         cds_list_for_each_entry(enabler_ref,
 520                         &event->enablers_ref_head, node) {
 521                 if (enabler_ref->ref == enabler)
 522                         return enabler_ref;
 523         }
 524         return NULL;
 525 }
 526
 527 /*
 528  * Create struct lttng_event if it is missing and present in the list of
 529  * tracepoint probes.
 530  */
 531 static
 532 void lttng_create_event_if_missing(struct lttng_enabler *enabler)
 533 {
 534         struct lttng_session *session = enabler->chan->session;
 535         struct lttng_probe_desc *probe_desc;
 536         const struct lttng_event_desc *desc;
 537         struct lttng_event *event;
 538         int i;
 539         struct cds_list_head *probe_list;
 540
 541         probe_list = lttng_get_probe_list_head();
 542         /*
 543          * For each probe event, if we find that a probe event matches
 544          * our enabler, create an associated lttng_event if not
 545          * already present.
 546          */
 547         cds_list_for_each_entry(probe_desc, probe_list, head) {
 548                 for (i = 0; i < probe_desc->nr_events; i++) {
 549                         int found = 0, ret;
 550                         struct cds_hlist_head *head;
 551                         struct cds_hlist_node *node;
 552                         const char *event_name;
 553                         size_t name_len;
 554                         uint32_t hash;
 555
 556                         desc = probe_desc->event_desc[i];
 557                         if (!lttng_desc_match_enabler(desc, enabler))
 558                                 continue;
 559                         event_name = desc->name;
 560                         name_len = strlen(event_name);
 561
 562                         /*
 563                          * Check if already created.
 564                          */
 565                         hash = jhash(event_name, name_len, 0);
 566                         head = &session->events_ht.table[hash & (LTTNG_UST_EVENT_HT_SIZE - 1)];
 567                         cds_hlist_for_each_entry(event, node, head, hlist) {
 568                                 if (event->desc == desc
 569                                                 && event->chan == enabler->chan)
 570                                         found = 1;
 571                         }
 572                         if (found)
 573                                 continue;
 574
 575                         /*
 576                          * We need to create an event for this
 577                          * event probe.
 578                          */
 579                         ret = lttng_event_create(probe_desc->event_desc[i],
 580                                         enabler->chan);
 581                         if (ret) {
 582                                 DBG("Unable to create event %s, error %d\n",
 583                                         probe_desc->event_desc[i]->name, ret);
 584                         }
 585                 }
 586         }
 587 }
 588
 589 /*
 590  * Create events associated with an enabler (if not already present),
 591  * and add backward reference from the event to the enabler.
 592  */
 593 static
 594 int lttng_enabler_ref_events(struct lttng_enabler *enabler)
 595 {
 596         struct lttng_session *session = enabler->chan->session;
 597         struct lttng_event *event;
 598
 599         /* First ensure that probe events are created for this enabler. */
 600         lttng_create_event_if_missing(enabler);
 601
 602         /* For each event matching enabler in session event list. */
 603         cds_list_for_each_entry(event, &session->events_head, node) {
 604                 struct lttng_enabler_ref *enabler_ref;
 605
 606                 if (!lttng_event_match_enabler(event, enabler))
 607                         continue;
 608
 609                 enabler_ref = lttng_event_enabler_ref(event, enabler);
 610                 if (!enabler_ref) {
 611                         /*
 612                          * If no backward ref, create it.
 613                          * Add backward ref from event to enabler.
 614                          */
 615                         enabler_ref = zmalloc(sizeof(*enabler_ref));
 616                         if (!enabler_ref)
 617                                 return -ENOMEM;
 618                         enabler_ref->ref = enabler;
 619                         cds_list_add(&enabler_ref->node,
 620                                 &event->enablers_ref_head);
 621                 }
 622
 623                 /*
 624                  * Link filter bytecodes if not linked yet.
 625                  */
 626                 lttng_enabler_event_link_bytecode(event, enabler);
 627
 628                 /* TODO: merge event context. */
 629         }
 630         return 0;
 631 }
 632
 633 /*
 634  * Called at library load: connect the probe on all enablers matching
 635  * this event.
 636  * Called with session mutex held.
 637  */
 638 int lttng_fix_pending_events(void)
 639 {
 640         struct lttng_session *session;
 641
 642         cds_list_for_each_entry(session, &sessions, node) {
 643                 lttng_session_lazy_sync_enablers(session);
 644         }
 645         return 0;
 646 }
 647
 648 /*
 649  * Only used internally at session destruction.
 650  */
 651 static
 652 void _lttng_event_destroy(struct lttng_event *event)
 653 {
 654         struct lttng_enabler_ref *enabler_ref, *tmp_enabler_ref;
 655
 656         cds_list_del(&event->node);
 657         lttng_destroy_context(event->ctx);
 658         lttng_free_event_filter_runtime(event);
 659         /* Free event enabler refs */
 660         cds_list_for_each_entry_safe(enabler_ref, tmp_enabler_ref,
 661                         &event->enablers_ref_head, node)
 662                 free(enabler_ref);
 663         free(event);
 664 }
 665
 666 void lttng_ust_events_exit(void)
 667 {
 668         struct lttng_session *session, *tmpsession;
 669
 670         cds_list_for_each_entry_safe(session, tmpsession, &sessions, node)
 671                 lttng_session_destroy(session);
 672 }
 673
 674 /*
 675  * Enabler management.
 676  */
 677 struct lttng_enabler *lttng_enabler_create(enum lttng_enabler_type type,
 678                 struct lttng_ust_event *event_param,
 679                 struct lttng_channel *chan)
 680 {
 681         struct lttng_enabler *enabler;
 682
 683         enabler = zmalloc(sizeof(*enabler));
 684         if (!enabler)
 685                 return NULL;
 686         enabler->type = type;
 687         CDS_INIT_LIST_HEAD(&enabler->filter_bytecode_head);
 688         memcpy(&enabler->event_param, event_param,
 689                 sizeof(enabler->event_param));
 690         enabler->chan = chan;
 691         /* ctx left NULL */
 692         enabler->enabled = 1;
 693         cds_list_add(&enabler->node, &enabler->chan->session->enablers_head);
 694         lttng_session_lazy_sync_enablers(enabler->chan->session);
 695         return enabler;
 696 }
 697
 698 int lttng_enabler_enable(struct lttng_enabler *enabler)
 699 {
 700         enabler->enabled = 1;
 701         lttng_session_lazy_sync_enablers(enabler->chan->session);
 702         return 0;
 703 }
 704
 705 int lttng_enabler_disable(struct lttng_enabler *enabler)
 706 {
 707         enabler->enabled = 0;
 708         lttng_session_lazy_sync_enablers(enabler->chan->session);
 709         return 0;
 710 }
 711
 712 int lttng_enabler_attach_bytecode(struct lttng_enabler *enabler,
 713                 struct lttng_ust_filter_bytecode_node *bytecode)
 714 {
 715         bytecode->enabler = enabler;
 716         cds_list_add_tail(&bytecode->node, &enabler->filter_bytecode_head);
 717         lttng_session_lazy_sync_enablers(enabler->chan->session);
 718         return 0;
 719 }
 720
 721 int lttng_attach_context(struct lttng_ust_context *context_param,
 722                 struct lttng_ctx **ctx, struct lttng_session *session)
 723 {
 724         /*
 725          * We cannot attach a context after trace has been started for a
 726          * session because the metadata does not allow expressing this
 727          * information outside of the original channel scope.
 728          */
 729         if (session->been_active)
 730                 return -EPERM;
 731
 732         switch (context_param->ctx) {
 733         case LTTNG_UST_CONTEXT_PTHREAD_ID:
 734                 return lttng_add_pthread_id_to_ctx(ctx);
 735         case LTTNG_UST_CONTEXT_VTID:
 736                 return lttng_add_vtid_to_ctx(ctx);
 737         case LTTNG_UST_CONTEXT_VPID:
 738                 return lttng_add_vpid_to_ctx(ctx);
 739         case LTTNG_UST_CONTEXT_PROCNAME:
 740                 return lttng_add_procname_to_ctx(ctx);
 741         case LTTNG_UST_CONTEXT_IP:
 742                 return lttng_add_ip_to_ctx(ctx);
 743         default:
 744                 return -EINVAL;
 745         }
 746 }
 747
 748 int lttng_enabler_attach_context(struct lttng_enabler *enabler,
 749                 struct lttng_ust_context *context_param)
 750 {
 751 #if 0   // disabled for now.
 752         struct lttng_session *session = enabler->chan->session;
 753         int ret;
 754
 755         ret = lttng_attach_context(context_param, &enabler->ctx,
 756                         session);
 757         if (ret)
 758                 return ret;
 759         lttng_session_lazy_sync_enablers(enabler->chan->session);
 760 #endif
 761         return -ENOSYS;
 762 }
 763
 764 static
 765 void lttng_enabler_destroy(struct lttng_enabler *enabler)
 766 {
 767         struct lttng_ust_filter_bytecode_node *filter_node, *tmp_filter_node;
 768
 769         /* Destroy filter bytecode */
 770         cds_list_for_each_entry_safe(filter_node, tmp_filter_node,
 771                         &enabler->filter_bytecode_head, node) {
 772                 free(filter_node);
 773         }
 774
 775         /* Destroy contexts */
 776         lttng_destroy_context(enabler->ctx);
 777
 778         cds_list_del(&enabler->node);
 779         free(enabler);
 780 }
 781
 782 /*
 783  * lttng_session_sync_enablers should be called just before starting a
 784  * session.
 785  */
 786 static
 787 void lttng_session_sync_enablers(struct lttng_session *session)
 788 {
 789         struct lttng_enabler *enabler;
 790         struct lttng_event *event;
 791
 792         cds_list_for_each_entry(enabler, &session->enablers_head, node)
 793                 lttng_enabler_ref_events(enabler);
 794         /*
 795          * For each event, if at least one of its enablers is enabled,
 796          * and its channel and session transient states are enabled, we
 797          * enable the event, else we disable it.
 798          */
 799         cds_list_for_each_entry(event, &session->events_head, node) {
 800                 struct lttng_enabler_ref *enabler_ref;
 801                 struct lttng_bytecode_runtime *runtime;
 802                 int enabled = 0, has_enablers_without_bytecode = 0;
 803
 804                 /* Enable events */
 805                 cds_list_for_each_entry(enabler_ref,
 806                                 &event->enablers_ref_head, node) {
 807                         if (enabler_ref->ref->enabled) {
 808                                 enabled = 1;
 809                                 break;
 810                         }
 811                 }
 812                 /*
 813                  * Enabled state is based on union of enablers, with
 814                  * intesection of session and channel transient enable
 815                  * states.
 816                  */
 817                 enabled = enabled && session->tstate && event->chan->tstate;
 818
 819                 CMM_STORE_SHARED(event->enabled, enabled);
 820                 /*
 821                  * Sync tracepoint registration with event enabled
 822                  * state.
 823                  */
 824                 if (enabled) {
 825                         if (!event->registered)
 826                                 register_event(event);
 827                 } else {
 828                         if (event->registered)
 829                                 unregister_event(event);
 830                 }
 831
 832                 /* Check if has enablers without bytecode enabled */
 833                 cds_list_for_each_entry(enabler_ref,
 834                                 &event->enablers_ref_head, node) {
 835                         if (enabler_ref->ref->enabled
 836                                         && cds_list_empty(&enabler_ref->ref->filter_bytecode_head)) {
 837                                 has_enablers_without_bytecode = 1;
 838                                 break;
 839                         }
 840                 }
 841                 event->has_enablers_without_bytecode =
 842                         has_enablers_without_bytecode;
 843
 844                 /* Enable filters */
 845                 cds_list_for_each_entry(runtime,
 846                                 &event->bytecode_runtime_head, node) {
 847                         lttng_filter_sync_state(runtime);
 848                 }
 849         }
 850 }
 851
 852 /*
 853  * Apply enablers to session events, adding events to session if need
 854  * be. It is required after each modification applied to an active
 855  * session, and right before session "start".
 856  * "lazy" sync means we only sync if required.
 857  */
 858 static
 859 void lttng_session_lazy_sync_enablers(struct lttng_session *session)
 860 {
 861         /* We can skip if session is not active */
 862         if (!session->active)
 863                 return;
 864         lttng_session_sync_enablers(session);
 865 }