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 (req_type == LTTNG_UST_LOGLEVEL_ALL)
 110                 return 1;
 111         if (!has_loglevel)
 112                 loglevel = TRACE_DEFAULT;
 113         switch (req_type) {
 114         case LTTNG_UST_LOGLEVEL_RANGE:
 115                 if (loglevel <= req_loglevel || req_loglevel == -1)
 116                         return 1;
 117                 else
 118                         return 0;
 119         case LTTNG_UST_LOGLEVEL_SINGLE:
 120                 if (loglevel == req_loglevel || req_loglevel == -1)
 121                         return 1;
 122                 else
 123                         return 0;
 124         case LTTNG_UST_LOGLEVEL_ALL:
 125         default:
 126                 return 1;
 127         }
 128 }
 129
 130 void synchronize_trace(void)
 131 {
 132         synchronize_rcu();
 133 }
 134
 135 struct lttng_session *lttng_session_create(void)
 136 {
 137         struct lttng_session *session;
 138         int i;
 139
 140         session = zmalloc(sizeof(struct lttng_session));
 141         if (!session)
 142                 return NULL;
 143         CDS_INIT_LIST_HEAD(&session->chan_head);
 144         CDS_INIT_LIST_HEAD(&session->events_head);
 145         CDS_INIT_LIST_HEAD(&session->enablers_head);
 146         for (i = 0; i < LTTNG_UST_EVENT_HT_SIZE; i++)
 147                 CDS_INIT_HLIST_HEAD(&session->events_ht.table[i]);
 148         cds_list_add(&session->node, &sessions);
 149         return session;
 150 }
 151
 152 /*
 153  * Only used internally at session destruction.
 154  */
 155 static
 156 void _lttng_channel_unmap(struct lttng_channel *lttng_chan)
 157 {
 158         struct channel *chan;
 159         struct lttng_ust_shm_handle *handle;
 160
 161         cds_list_del(&lttng_chan->node);
 162         lttng_destroy_context(lttng_chan->ctx);
 163         chan = lttng_chan->chan;
 164         handle = lttng_chan->handle;
 165         /*
 166          * note: lttng_chan is private data contained within handle. It
 167          * will be freed along with the handle.
 168          */
 169         channel_destroy(chan, handle, 0);
 170 }
 171
 172 static
 173 void register_event(struct lttng_event *event)
 174 {
 175         int ret;
 176         const struct lttng_event_desc *desc;
 177
 178         assert(event->registered == 0);
 179         desc = event->desc;
 180         ret = __tracepoint_probe_register(desc->name,
 181                         desc->probe_callback,
 182                         event, desc->signature);
 183         WARN_ON_ONCE(ret);
 184         if (!ret)
 185                 event->registered = 1;
 186 }
 187
 188 static
 189 void unregister_event(struct lttng_event *event)
 190 {
 191         int ret;
 192         const struct lttng_event_desc *desc;
 193
 194         assert(event->registered == 1);
 195         desc = event->desc;
 196         ret = __tracepoint_probe_unregister(desc->name,
 197                         desc->probe_callback,
 198                         event);
 199         WARN_ON_ONCE(ret);
 200         if (!ret)
 201                 event->registered = 0;
 202 }
 203
 204 /*
 205  * Only used internally at session destruction.
 206  */
 207 static
 208 void _lttng_event_unregister(struct lttng_event *event)
 209 {
 210         if (event->registered)
 211                 unregister_event(event);
 212 }
 213
 214 void lttng_session_destroy(struct lttng_session *session)
 215 {
 216         struct lttng_channel *chan, *tmpchan;
 217         struct lttng_event *event, *tmpevent;
 218         struct lttng_enabler *enabler, *tmpenabler;
 219
 220         CMM_ACCESS_ONCE(session->active) = 0;
 221         cds_list_for_each_entry(event, &session->events_head, node) {
 222                 _lttng_event_unregister(event);
 223         }
 224         synchronize_trace();    /* Wait for in-flight events to complete */
 225         cds_list_for_each_entry_safe(enabler, tmpenabler,
 226                         &session->enablers_head, node)
 227                 lttng_enabler_destroy(enabler);
 228         cds_list_for_each_entry_safe(event, tmpevent,
 229                         &session->events_head, node)
 230                 _lttng_event_destroy(event);
 231         cds_list_for_each_entry_safe(chan, tmpchan, &session->chan_head, node)
 232                 _lttng_channel_unmap(chan);
 233         cds_list_del(&session->node);
 234         free(session);
 235 }
 236
 237 int lttng_session_enable(struct lttng_session *session)
 238 {
 239         int ret = 0;
 240         struct lttng_channel *chan;
 241         int notify_socket;
 242
 243         if (session->active) {
 244                 ret = -EBUSY;
 245                 goto end;
 246         }
 247
 248         notify_socket = lttng_get_notify_socket(session->owner);
 249         if (notify_socket < 0)
 250                 return notify_socket;
 251
 252         /* Set transient enabler state to "enabled" */
 253         session->tstate = 1;
 254         /* We need to sync enablers with session before activation. */
 255         lttng_session_sync_enablers(session);
 256
 257         /*
 258          * Snapshot the number of events per channel to know the type of header
 259          * we need to use.
 260          */
 261         cds_list_for_each_entry(chan, &session->chan_head, node) {
 262                 const struct lttng_ctx *ctx;
 263                 const struct lttng_ctx_field *fields = NULL;
 264                 size_t nr_fields = 0;
 265                 uint32_t chan_id;
 266
 267                 /* don't change it if session stop/restart */
 268                 if (chan->header_type)
 269                         continue;
 270                 ctx = chan->ctx;
 271                 if (ctx) {
 272                         nr_fields = ctx->nr_fields;
 273                         fields = ctx->fields;
 274                 }
 275                 ret = ustcomm_register_channel(notify_socket,
 276                         session->objd,
 277                         chan->objd,
 278                         nr_fields,
 279                         fields,
 280                         &chan_id,
 281                         &chan->header_type);
 282                 if (ret) {
 283                         DBG("Error (%d) registering channel to sessiond", ret);
 284                         return ret;
 285                 }
 286                 if (chan_id != chan->id) {
 287                         DBG("Error: channel registration id (%u) does not match id assigned at creation (%u)",
 288                                 chan_id, chan->id);
 289                         return -EINVAL;
 290                 }
 291         }
 292
 293         /* Set atomically the state to "active" */
 294         CMM_ACCESS_ONCE(session->active) = 1;
 295         CMM_ACCESS_ONCE(session->been_active) = 1;
 296
 297         lttng_ust_sockinfo_session_enabled(session->owner, session);
 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  * Only used internally at session destruction.
 679  */
 680 static
 681 void _lttng_event_destroy(struct lttng_event *event)
 682 {
 683         struct lttng_enabler_ref *enabler_ref, *tmp_enabler_ref;
 684
 685         cds_list_del(&event->node);
 686         lttng_destroy_context(event->ctx);
 687         lttng_free_event_filter_runtime(event);
 688         /* Free event enabler refs */
 689         cds_list_for_each_entry_safe(enabler_ref, tmp_enabler_ref,
 690                         &event->enablers_ref_head, node)
 691                 free(enabler_ref);
 692         free(event);
 693 }
 694
 695 void lttng_ust_events_exit(void)
 696 {
 697         struct lttng_session *session, *tmpsession;
 698
 699         cds_list_for_each_entry_safe(session, tmpsession, &sessions, node)
 700                 lttng_session_destroy(session);
 701 }
 702
 703 /*
 704  * Enabler management.
 705  */
 706 struct lttng_enabler *lttng_enabler_create(enum lttng_enabler_type type,
 707                 struct lttng_ust_event *event_param,
 708                 struct lttng_channel *chan)
 709 {
 710         struct lttng_enabler *enabler;
 711
 712         enabler = zmalloc(sizeof(*enabler));
 713         if (!enabler)
 714                 return NULL;
 715         enabler->type = type;
 716         CDS_INIT_LIST_HEAD(&enabler->filter_bytecode_head);
 717         CDS_INIT_LIST_HEAD(&enabler->excluder_head);
 718         memcpy(&enabler->event_param, event_param,
 719                 sizeof(enabler->event_param));
 720         enabler->chan = chan;
 721         /* ctx left NULL */
 722         enabler->enabled = 1;
 723         cds_list_add(&enabler->node, &enabler->chan->session->enablers_head);
 724         lttng_session_lazy_sync_enablers(enabler->chan->session);
 725         return enabler;
 726 }
 727
 728 int lttng_enabler_enable(struct lttng_enabler *enabler)
 729 {
 730         enabler->enabled = 1;
 731         lttng_session_lazy_sync_enablers(enabler->chan->session);
 732         return 0;
 733 }
 734
 735 int lttng_enabler_disable(struct lttng_enabler *enabler)
 736 {
 737         enabler->enabled = 0;
 738         lttng_session_lazy_sync_enablers(enabler->chan->session);
 739         return 0;
 740 }
 741
 742 int lttng_enabler_attach_bytecode(struct lttng_enabler *enabler,
 743                 struct lttng_ust_filter_bytecode_node *bytecode)
 744 {
 745         bytecode->enabler = enabler;
 746         cds_list_add_tail(&bytecode->node, &enabler->filter_bytecode_head);
 747         lttng_session_lazy_sync_enablers(enabler->chan->session);
 748         return 0;
 749 }
 750
 751 int lttng_enabler_attach_exclusion(struct lttng_enabler *enabler,
 752                 struct lttng_ust_excluder_node *excluder)
 753 {
 754         excluder->enabler = enabler;
 755         cds_list_add_tail(&excluder->node, &enabler->excluder_head);
 756         lttng_session_lazy_sync_enablers(enabler->chan->session);
 757         return 0;
 758 }
 759
 760 int lttng_attach_context(struct lttng_ust_context *context_param,
 761                 struct lttng_ctx **ctx, struct lttng_session *session)
 762 {
 763         /*
 764          * We cannot attach a context after trace has been started for a
 765          * session because the metadata does not allow expressing this
 766          * information outside of the original channel scope.
 767          */
 768         if (session->been_active)
 769                 return -EPERM;
 770
 771         switch (context_param->ctx) {
 772         case LTTNG_UST_CONTEXT_PTHREAD_ID:
 773                 return lttng_add_pthread_id_to_ctx(ctx);
 774         case LTTNG_UST_CONTEXT_VTID:
 775                 return lttng_add_vtid_to_ctx(ctx);
 776         case LTTNG_UST_CONTEXT_VPID:
 777                 return lttng_add_vpid_to_ctx(ctx);
 778         case LTTNG_UST_CONTEXT_PROCNAME:
 779                 return lttng_add_procname_to_ctx(ctx);
 780         case LTTNG_UST_CONTEXT_IP:
 781                 return lttng_add_ip_to_ctx(ctx);
 782         default:
 783                 return -EINVAL;
 784         }
 785 }
 786
 787 int lttng_enabler_attach_context(struct lttng_enabler *enabler,
 788                 struct lttng_ust_context *context_param)
 789 {
 790 #if 0   // disabled for now.
 791         struct lttng_session *session = enabler->chan->session;
 792         int ret;
 793
 794         ret = lttng_attach_context(context_param, &enabler->ctx,
 795                         session);
 796         if (ret)
 797                 return ret;
 798         lttng_session_lazy_sync_enablers(enabler->chan->session);
 799 #endif
 800         return -ENOSYS;
 801 }
 802
 803 static
 804 void lttng_enabler_destroy(struct lttng_enabler *enabler)
 805 {
 806         struct lttng_ust_filter_bytecode_node *filter_node, *tmp_filter_node;
 807         struct lttng_ust_excluder_node *excluder_node, *tmp_excluder_node;
 808
 809         /* Destroy filter bytecode */
 810         cds_list_for_each_entry_safe(filter_node, tmp_filter_node,
 811                         &enabler->filter_bytecode_head, node) {
 812                 free(filter_node);
 813         }
 814
 815         /* Destroy excluders */
 816         cds_list_for_each_entry_safe(excluder_node, tmp_excluder_node,
 817                         &enabler->excluder_head, node) {
 818                 free(excluder_node);
 819         }
 820
 821         /* Destroy contexts */
 822         lttng_destroy_context(enabler->ctx);
 823
 824         cds_list_del(&enabler->node);
 825         free(enabler);
 826 }
 827
 828 /*
 829  * lttng_session_sync_enablers should be called just before starting a
 830  * session.
 831  */
 832 static
 833 void lttng_session_sync_enablers(struct lttng_session *session)
 834 {
 835         struct lttng_enabler *enabler;
 836         struct lttng_event *event;
 837
 838         cds_list_for_each_entry(enabler, &session->enablers_head, node)
 839                 lttng_enabler_ref_events(enabler);
 840         /*
 841          * For each event, if at least one of its enablers is enabled,
 842          * and its channel and session transient states are enabled, we
 843          * enable the event, else we disable it.
 844          */
 845         cds_list_for_each_entry(event, &session->events_head, node) {
 846                 struct lttng_enabler_ref *enabler_ref;
 847                 struct lttng_bytecode_runtime *runtime;
 848                 int enabled = 0, has_enablers_without_bytecode = 0;
 849
 850                 /* Enable events */
 851                 cds_list_for_each_entry(enabler_ref,
 852                                 &event->enablers_ref_head, node) {
 853                         if (enabler_ref->ref->enabled) {
 854                                 enabled = 1;
 855                                 break;
 856                         }
 857                 }
 858                 /*
 859                  * Enabled state is based on union of enablers, with
 860                  * intesection of session and channel transient enable
 861                  * states.
 862                  */
 863                 enabled = enabled && session->tstate && event->chan->tstate;
 864
 865                 CMM_STORE_SHARED(event->enabled, enabled);
 866                 /*
 867                  * Sync tracepoint registration with event enabled
 868                  * state.
 869                  */
 870                 if (enabled) {
 871                         if (!event->registered)
 872                                 register_event(event);
 873                 } else {
 874                         if (event->registered)
 875                                 unregister_event(event);
 876                 }
 877
 878                 /* Check if has enablers without bytecode enabled */
 879                 cds_list_for_each_entry(enabler_ref,
 880                                 &event->enablers_ref_head, node) {
 881                         if (enabler_ref->ref->enabled
 882                                         && cds_list_empty(&enabler_ref->ref->filter_bytecode_head)) {
 883                                 has_enablers_without_bytecode = 1;
 884                                 break;
 885                         }
 886                 }
 887                 event->has_enablers_without_bytecode =
 888                         has_enablers_without_bytecode;
 889
 890                 /* Enable filters */
 891                 cds_list_for_each_entry(runtime,
 892                                 &event->bytecode_runtime_head, node) {
 893                         lttng_filter_sync_state(runtime);
 894                 }
 895         }
 896 }
 897
 898 /*
 899  * Apply enablers to session events, adding events to session if need
 900  * be. It is required after each modification applied to an active
 901  * session, and right before session "start".
 902  * "lazy" sync means we only sync if required.
 903  */
 904 static
 905 void lttng_session_lazy_sync_enablers(struct lttng_session *session)
 906 {
 907         /* We can skip if session is not active */
 908         if (!session->active)
 909                 return;
 910         lttng_session_sync_enablers(session);
 911 }