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