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 "error.h"
  49 #include "compat.h"
  50 #include "lttng-ust-uuid.h"
  51
  52 #include "tracepoint-internal.h"
  53 #include "lttng-tracer.h"
  54 #include "lttng-tracer-core.h"
  55 #include "wait.h"
  56 #include "../libringbuffer/shm.h"
  57 #include "jhash.h"
  58
  59 /*
  60  * The sessions mutex is the centralized mutex across UST tracing
  61  * control and probe registration. All operations within this file are
  62  * called by the communication thread, under ust_lock protection.
  63  */
  64 static pthread_mutex_t sessions_mutex = PTHREAD_MUTEX_INITIALIZER;
  65
  66 void ust_lock(void)
  67 {
  68         pthread_mutex_lock(&sessions_mutex);
  69 }
  70
  71 void ust_unlock(void)
  72 {
  73         pthread_mutex_unlock(&sessions_mutex);
  74 }
  75
  76 static CDS_LIST_HEAD(sessions);
  77
  78 static void _lttng_event_destroy(struct lttng_event *event);
  79 static void _lttng_channel_destroy(struct lttng_channel *chan);
  80 static int _lttng_event_unregister(struct lttng_event *event);
  81 static
  82 int _lttng_event_metadata_statedump(struct lttng_session *session,
  83                                   struct lttng_channel *chan,
  84                                   struct lttng_event *event);
  85 static
  86 int _lttng_session_metadata_statedump(struct lttng_session *session);
  87
  88 static
  89 void lttng_session_lazy_sync_enablers(struct lttng_session *session);
  90 static
  91 void lttng_session_sync_enablers(struct lttng_session *session);
  92 static
  93 void lttng_enabler_destroy(struct lttng_enabler *enabler);
  94
  95 static
  96 int lttng_loglevel_match(int loglevel,
  97                 unsigned int has_loglevel,
  98                 enum lttng_ust_loglevel_type req_type,
  99                 int req_loglevel)
 100 {
 101         if (req_type == LTTNG_UST_LOGLEVEL_ALL)
 102                 return 1;
 103         if (!has_loglevel)
 104                 loglevel = TRACE_DEFAULT;
 105         switch (req_type) {
 106         case LTTNG_UST_LOGLEVEL_RANGE:
 107                 if (loglevel <= req_loglevel || req_loglevel == -1)
 108                         return 1;
 109                 else
 110                         return 0;
 111         case LTTNG_UST_LOGLEVEL_SINGLE:
 112                 if (loglevel == req_loglevel || req_loglevel == -1)
 113                         return 1;
 114                 else
 115                         return 0;
 116         case LTTNG_UST_LOGLEVEL_ALL:
 117         default:
 118                 return 1;
 119         }
 120 }
 121
 122 void synchronize_trace(void)
 123 {
 124         synchronize_rcu();
 125 }
 126
 127 struct lttng_session *lttng_session_create(void)
 128 {
 129         struct lttng_session *session;
 130         int ret, i;
 131
 132         session = zmalloc(sizeof(struct lttng_session));
 133         if (!session)
 134                 return NULL;
 135         CDS_INIT_LIST_HEAD(&session->chan_head);
 136         CDS_INIT_LIST_HEAD(&session->events_head);
 137         CDS_INIT_LIST_HEAD(&session->enablers_head);
 138         for (i = 0; i < LTTNG_UST_EVENT_HT_SIZE; i++)
 139                 CDS_INIT_HLIST_HEAD(&session->events_ht.table[i]);
 140         ret = lttng_ust_uuid_generate(session->uuid);
 141         if (ret != 0) {
 142                 session->uuid[0] = '\0';
 143         }
 144         cds_list_add(&session->node, &sessions);
 145         return session;
 146 }
 147
 148 void lttng_session_destroy(struct lttng_session *session)
 149 {
 150         struct lttng_channel *chan, *tmpchan;
 151         struct lttng_event *event, *tmpevent;
 152         struct lttng_enabler *enabler, *tmpenabler;
 153         int ret;
 154
 155         CMM_ACCESS_ONCE(session->active) = 0;
 156         cds_list_for_each_entry(event, &session->events_head, node) {
 157                 ret = _lttng_event_unregister(event);
 158                 WARN_ON(ret);
 159         }
 160         synchronize_trace();    /* Wait for in-flight events to complete */
 161         cds_list_for_each_entry_safe(enabler, tmpenabler,
 162                         &session->enablers_head, node)
 163                 lttng_enabler_destroy(enabler);
 164         cds_list_for_each_entry_safe(event, tmpevent,
 165                         &session->events_head, node)
 166                 _lttng_event_destroy(event);
 167         cds_list_for_each_entry_safe(chan, tmpchan, &session->chan_head, node)
 168                 _lttng_channel_destroy(chan);
 169         cds_list_del(&session->node);
 170         free(session);
 171 }
 172
 173 int lttng_session_enable(struct lttng_session *session)
 174 {
 175         int ret = 0;
 176         struct lttng_channel *chan;
 177
 178         if (session->active) {
 179                 ret = -EBUSY;
 180                 goto end;
 181         }
 182
 183         /* We need to sync enablers with session before activation. */
 184         lttng_session_sync_enablers(session);
 185
 186         /*
 187          * Snapshot the number of events per channel to know the type of header
 188          * we need to use.
 189          */
 190         cds_list_for_each_entry(chan, &session->chan_head, node) {
 191                 if (chan->header_type)
 192                         continue;               /* don't change it if session stop/restart */
 193                 if (chan->free_event_id < 31)
 194                         chan->header_type = 1;  /* compact */
 195                 else
 196                         chan->header_type = 2;  /* large */
 197         }
 198
 199         CMM_ACCESS_ONCE(session->active) = 1;
 200         CMM_ACCESS_ONCE(session->been_active) = 1;
 201         ret = _lttng_session_metadata_statedump(session);
 202         if (ret)
 203                 CMM_ACCESS_ONCE(session->active) = 0;
 204 end:
 205         return ret;
 206 }
 207
 208 int lttng_session_disable(struct lttng_session *session)
 209 {
 210         int ret = 0;
 211
 212         if (!session->active) {
 213                 ret = -EBUSY;
 214                 goto end;
 215         }
 216         CMM_ACCESS_ONCE(session->active) = 0;
 217 end:
 218         return ret;
 219 }
 220
 221 int lttng_channel_enable(struct lttng_channel *channel)
 222 {
 223         int old;
 224
 225         if (channel == channel->session->metadata)
 226                 return -EPERM;
 227         old = uatomic_xchg(&channel->enabled, 1);
 228         if (old)
 229                 return -EEXIST;
 230         return 0;
 231 }
 232
 233 int lttng_channel_disable(struct lttng_channel *channel)
 234 {
 235         int old;
 236
 237         if (channel == channel->session->metadata)
 238                 return -EPERM;
 239         old = uatomic_xchg(&channel->enabled, 0);
 240         if (!old)
 241                 return -EEXIST;
 242         return 0;
 243 }
 244
 245 int lttng_event_enable(struct lttng_event *event)
 246 {
 247         int old;
 248
 249         if (event->chan == event->chan->session->metadata)
 250                 return -EPERM;
 251         old = uatomic_xchg(&event->enabled, 1);
 252         if (old)
 253                 return -EEXIST;
 254         return 0;
 255 }
 256
 257 int lttng_event_disable(struct lttng_event *event)
 258 {
 259         int old;
 260
 261         if (event->chan == event->chan->session->metadata)
 262                 return -EPERM;
 263         old = uatomic_xchg(&event->enabled, 0);
 264         if (!old)
 265                 return -EEXIST;
 266         return 0;
 267 }
 268
 269 struct lttng_channel *lttng_channel_create(struct lttng_session *session,
 270                                        const char *transport_name,
 271                                        void *buf_addr,
 272                                        size_t subbuf_size, size_t num_subbuf,
 273                                        unsigned int switch_timer_interval,
 274                                        unsigned int read_timer_interval,
 275                                        int **shm_fd, int **wait_fd,
 276                                        uint64_t **memory_map_size,
 277                                        struct lttng_channel *chan_priv_init)
 278 {
 279         struct lttng_channel *chan = NULL;
 280         struct lttng_transport *transport;
 281
 282         if (session->been_active)
 283                 goto active;    /* Refuse to add channel to active session */
 284         transport = lttng_transport_find(transport_name);
 285         if (!transport) {
 286                 DBG("LTTng transport %s not found\n",
 287                        transport_name);
 288                 goto notransport;
 289         }
 290         chan_priv_init->id = session->free_chan_id++;
 291         chan_priv_init->session = session;
 292         /*
 293          * Note: the channel creation op already writes into the packet
 294          * headers. Therefore the "chan" information used as input
 295          * should be already accessible.
 296          */
 297         chan = transport->ops.channel_create(transport_name, buf_addr,
 298                         subbuf_size, num_subbuf, switch_timer_interval,
 299                         read_timer_interval, shm_fd, wait_fd,
 300                         memory_map_size, chan_priv_init);
 301         if (!chan)
 302                 goto create_error;
 303         chan->enabled = 1;
 304         chan->ops = &transport->ops;
 305         cds_list_add(&chan->node, &session->chan_head);
 306         return chan;
 307
 308 create_error:
 309 notransport:
 310 active:
 311         return NULL;
 312 }
 313
 314 /*
 315  * Only used internally at session destruction.
 316  */
 317 static
 318 void _lttng_channel_destroy(struct lttng_channel *chan)
 319 {
 320         cds_list_del(&chan->node);
 321         lttng_destroy_context(chan->ctx);
 322         chan->ops->channel_destroy(chan);
 323 }
 324
 325 /*
 326  * Supports event creation while tracing session is active.
 327  */
 328 static
 329 int lttng_event_create(const struct lttng_event_desc *desc,
 330                 struct lttng_channel *chan)
 331 {
 332         const char *event_name = desc->name;
 333         struct lttng_event *event;
 334         struct cds_hlist_head *head;
 335         struct cds_hlist_node *node;
 336         int ret = 0;
 337         size_t name_len = strlen(event_name);
 338         uint32_t hash;
 339
 340         if (chan->used_event_id == -1U) {
 341                 ret = -ENOMEM;
 342                 goto full;
 343         }
 344         hash = jhash(event_name, name_len, 0);
 345         head = &chan->session->events_ht.table[hash & (LTTNG_UST_EVENT_HT_SIZE - 1)];
 346         cds_hlist_for_each_entry(event, node, head, hlist) {
 347                 assert(event->desc);
 348                 if (!strncmp(event->desc->name,
 349                                 desc->name,
 350                                 LTTNG_UST_SYM_NAME_LEN - 1)) {
 351                         ret = -EEXIST;
 352                         goto exist;
 353                 }
 354         }
 355
 356         /*
 357          * Check if loglevel match. Refuse to connect event if not.
 358          */
 359         event = zmalloc(sizeof(struct lttng_event));
 360         if (!event) {
 361                 ret = -ENOMEM;
 362                 goto cache_error;
 363         }
 364         event->chan = chan;
 365
 366         /*
 367          * used_event_id counts the maximum number of event IDs that can
 368          * register if all probes register.
 369          */
 370         chan->used_event_id++;
 371         event->enabled = 1;
 372         CDS_INIT_LIST_HEAD(&event->bytecode_runtime_head);
 373         CDS_INIT_LIST_HEAD(&event->enablers_ref_head);
 374         event->desc = desc;
 375         /* Populate lttng_event structure before tracepoint registration. */
 376         cmm_smp_wmb();
 377         ret = __tracepoint_probe_register(event_name,
 378                         desc->probe_callback,
 379                         event, desc->signature);
 380         if (ret)
 381                 goto register_error;
 382         event->id = chan->free_event_id++;
 383         ret = _lttng_event_metadata_statedump(chan->session, chan, event);
 384         if (ret)
 385                 goto statedump_error;
 386         cds_list_add(&event->node, &chan->session->events_head);
 387         cds_hlist_add_head(&event->hlist, head);
 388         return 0;
 389
 390 statedump_error:
 391         WARN_ON_ONCE(__tracepoint_probe_unregister(event_name,
 392                                 desc->probe_callback,
 393                                 event));
 394 register_error:
 395         free(event);
 396 cache_error:
 397 exist:
 398 full:
 399         return ret;
 400 }
 401
 402 static
 403 int lttng_desc_match_wildcard_enabler(const struct lttng_event_desc *desc,
 404                 struct lttng_enabler *enabler)
 405 {
 406         int loglevel = 0;
 407         unsigned int has_loglevel;
 408
 409         assert(enabler->type == LTTNG_ENABLER_WILDCARD);
 410         /* Compare excluding final '*' */
 411         if (strncmp(desc->name, enabler->event_param.name,
 412                         strlen(enabler->event_param.name) - 1))
 413                 return 0;
 414         if (desc->loglevel) {
 415                 loglevel = *(*desc->loglevel);
 416                 has_loglevel = 1;
 417         }
 418         if (!lttng_loglevel_match(loglevel,
 419                         has_loglevel,
 420                         enabler->event_param.loglevel_type,
 421                         enabler->event_param.loglevel))
 422                 return 0;
 423         return 1;
 424 }
 425
 426 static
 427 int lttng_desc_match_event_enabler(const struct lttng_event_desc *desc,
 428                 struct lttng_enabler *enabler)
 429 {
 430         int loglevel = 0;
 431         unsigned int has_loglevel = 0;
 432
 433         assert(enabler->type == LTTNG_ENABLER_EVENT);
 434         if (strcmp(desc->name, enabler->event_param.name))
 435                 return 0;
 436         if (desc->loglevel) {
 437                 loglevel = *(*desc->loglevel);
 438                 has_loglevel = 1;
 439         }
 440         if (!lttng_loglevel_match(loglevel,
 441                         has_loglevel,
 442                         enabler->event_param.loglevel_type,
 443                         enabler->event_param.loglevel))
 444                 return 0;
 445         return 1;
 446 }
 447
 448 static
 449 int lttng_desc_match_enabler(const struct lttng_event_desc *desc,
 450                 struct lttng_enabler *enabler)
 451 {
 452         switch (enabler->type) {
 453         case LTTNG_ENABLER_WILDCARD:
 454                 return lttng_desc_match_wildcard_enabler(desc, enabler);
 455         case LTTNG_ENABLER_EVENT:
 456                 return lttng_desc_match_event_enabler(desc, enabler);
 457         default:
 458                 return -EINVAL;
 459         }
 460 }
 461
 462 static
 463 int lttng_event_match_enabler(struct lttng_event *event,
 464                 struct lttng_enabler *enabler)
 465 {
 466         return lttng_desc_match_enabler(event->desc, enabler);
 467 }
 468
 469 static
 470 struct lttng_enabler_ref * lttng_event_enabler_ref(struct lttng_event *event,
 471                 struct lttng_enabler *enabler)
 472 {
 473         struct lttng_enabler_ref *enabler_ref;
 474
 475         cds_list_for_each_entry(enabler_ref,
 476                         &event->enablers_ref_head, node) {
 477                 if (enabler_ref->ref == enabler)
 478                         return enabler_ref;
 479         }
 480         return NULL;
 481 }
 482
 483 /*
 484  * Create struct lttng_event if it is missing and present in the list of
 485  * tracepoint probes.
 486  */
 487 static
 488 void lttng_create_event_if_missing(struct lttng_enabler *enabler)
 489 {
 490         struct lttng_session *session = enabler->chan->session;
 491         struct lttng_probe_desc *probe_desc;
 492         const struct lttng_event_desc *desc;
 493         struct lttng_event *event;
 494         int i;
 495         struct cds_list_head *probe_list;
 496
 497         probe_list = lttng_get_probe_list_head();
 498         /*
 499          * For each probe event, if we find that a probe event matches
 500          * our enabler, create an associated lttng_event if not
 501          * already present.
 502          */
 503         cds_list_for_each_entry(probe_desc, probe_list, head) {
 504                 for (i = 0; i < probe_desc->nr_events; i++) {
 505                         int found = 0, ret;
 506                         struct cds_hlist_head *head;
 507                         struct cds_hlist_node *node;
 508                         const char *event_name;
 509                         size_t name_len;
 510                         uint32_t hash;
 511
 512                         desc = probe_desc->event_desc[i];
 513                         if (!lttng_desc_match_enabler(desc, enabler))
 514                                 continue;
 515                         event_name = desc->name;
 516                         name_len = strlen(event_name);
 517
 518                         /*
 519                          * Check if already created.
 520                          */
 521                         hash = jhash(event_name, name_len, 0);
 522                         head = &session->events_ht.table[hash & (LTTNG_UST_EVENT_HT_SIZE - 1)];
 523                         cds_hlist_for_each_entry(event, node, head, hlist) {
 524                                 if (event->desc == desc)
 525                                         found = 1;
 526                         }
 527                         if (found)
 528                                 continue;
 529
 530                         /*
 531                          * We need to create an event for this
 532                          * event probe.
 533                          */
 534                         ret = lttng_event_create(probe_desc->event_desc[i],
 535                                         enabler->chan);
 536                         if (ret) {
 537                                 DBG("Unable to create event %s\n",
 538                                         probe_desc->event_desc[i]->name);
 539                         }
 540                 }
 541         }
 542 }
 543
 544 /*
 545  * Create events associated with an enabler (if not already present),
 546  * and add backward reference from the event to the enabler.
 547  */
 548 static
 549 int lttng_enabler_ref_events(struct lttng_enabler *enabler)
 550 {
 551         struct lttng_session *session = enabler->chan->session;
 552         struct lttng_event *event;
 553
 554         /* First ensure that probe events are created for this enabler. */
 555         lttng_create_event_if_missing(enabler);
 556
 557         /* For each event matching enabler in session event list. */
 558         cds_list_for_each_entry(event, &session->events_head, node) {
 559                 struct lttng_enabler_ref *enabler_ref;
 560
 561                 if (!lttng_event_match_enabler(event, enabler))
 562                         continue;
 563
 564                 enabler_ref = lttng_event_enabler_ref(event, enabler);
 565                 if (!enabler_ref) {
 566                         /*
 567                          * If no backward ref, create it.
 568                          * Add backward ref from event to enabler.
 569                          */
 570                         enabler_ref = zmalloc(sizeof(*enabler_ref));
 571                         if (!enabler_ref)
 572                                 return -ENOMEM;
 573                         enabler_ref->ref = enabler;
 574                         cds_list_add(&enabler_ref->node,
 575                                 &event->enablers_ref_head);
 576                 }
 577
 578                 /*
 579                  * Link filter bytecodes if not linked yet.
 580                  */
 581                 lttng_enabler_event_link_bytecode(event, enabler);
 582
 583                 /* TODO: merge event context. */
 584         }
 585         return 0;
 586 }
 587
 588 /*
 589  * Called at library load: connect the probe on all enablers matching
 590  * this event.
 591  * called with session mutex held.
 592  * TODO: currently, for each desc added, we iterate on all event desc
 593  * (inefficient). We should create specific code that only target the
 594  * added desc.
 595  */
 596 int lttng_fix_pending_event_desc(const struct lttng_event_desc *desc)
 597 {
 598         struct lttng_session *session;
 599
 600         cds_list_for_each_entry(session, &sessions, node) {
 601                 lttng_session_lazy_sync_enablers(session);
 602         }
 603         return 0;
 604 }
 605
 606 /*
 607  * Only used internally at session destruction.
 608  */
 609 int _lttng_event_unregister(struct lttng_event *event)
 610 {
 611         return __tracepoint_probe_unregister(event->desc->name,
 612                                           event->desc->probe_callback,
 613                                           event);
 614 }
 615
 616 /*
 617  * Only used internally at session destruction.
 618  */
 619 static
 620 void _lttng_event_destroy(struct lttng_event *event)
 621 {
 622         struct lttng_enabler_ref *enabler_ref, *tmp_enabler_ref;
 623
 624         cds_list_del(&event->node);
 625         lttng_destroy_context(event->ctx);
 626         lttng_free_event_filter_runtime(event);
 627         /* Free event enabler refs */
 628         cds_list_for_each_entry_safe(enabler_ref, tmp_enabler_ref,
 629                         &event->enablers_ref_head, node)
 630                 free(enabler_ref);
 631         free(event);
 632 }
 633
 634 /*
 635  * We have exclusive access to our metadata buffer (protected by the
 636  * ust_lock), so we can do racy operations such as looking for
 637  * remaining space left in packet and write, since mutual exclusion
 638  * protects us from concurrent writes.
 639  */
 640 int lttng_metadata_printf(struct lttng_session *session,
 641                           const char *fmt, ...)
 642 {
 643         struct lttng_ust_lib_ring_buffer_ctx ctx;
 644         struct lttng_channel *chan = session->metadata;
 645         char *str = NULL;
 646         int ret = 0, waitret;
 647         size_t len, reserve_len, pos;
 648         va_list ap;
 649
 650         WARN_ON_ONCE(!CMM_ACCESS_ONCE(session->active));
 651
 652         va_start(ap, fmt);
 653         ret = vasprintf(&str, fmt, ap);
 654         va_end(ap);
 655         if (ret < 0)
 656                 return -ENOMEM;
 657
 658         len = strlen(str);
 659         pos = 0;
 660
 661         for (pos = 0; pos < len; pos += reserve_len) {
 662                 reserve_len = min_t(size_t,
 663                                 chan->ops->packet_avail_size(chan->chan, chan->handle),
 664                                 len - pos);
 665                 lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL, reserve_len,
 666                                          sizeof(char), -1, chan->handle);
 667                 /*
 668                  * We don't care about metadata buffer's records lost
 669                  * count, because we always retry here. Report error if
 670                  * we need to bail out after timeout or being
 671                  * interrupted.
 672                  */
 673                 waitret = wait_cond_interruptible_timeout(
 674                         ({
 675                                 ret = chan->ops->event_reserve(&ctx, 0);
 676                                 ret != -ENOBUFS || !ret;
 677                         }),
 678                         LTTNG_METADATA_TIMEOUT_MSEC);
 679                 if (waitret == -ETIMEDOUT || waitret == -EINTR || ret) {
 680                         DBG("LTTng: Failure to write metadata to buffers (%s)\n",
 681                                 waitret == -EINTR ? "interrupted" :
 682                                         (ret == -ENOBUFS ? "timeout" : "I/O error"));
 683                         if (waitret == -EINTR)
 684                                 ret = waitret;
 685                         goto end;
 686                 }
 687                 chan->ops->event_write(&ctx, &str[pos], reserve_len);
 688                 chan->ops->event_commit(&ctx);
 689         }
 690 end:
 691         free(str);
 692         return ret;
 693 }
 694
 695 static
 696 int _lttng_field_statedump(struct lttng_session *session,
 697                          const struct lttng_event_field *field)
 698 {
 699         int ret = 0;
 700
 701         if (field->nowrite)
 702                 return 0;
 703
 704         switch (field->type.atype) {
 705         case atype_integer:
 706                 ret = lttng_metadata_printf(session,
 707                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s;\n",
 708                         field->type.u.basic.integer.size,
 709                         field->type.u.basic.integer.alignment,
 710                         field->type.u.basic.integer.signedness,
 711                         (field->type.u.basic.integer.encoding == lttng_encode_none)
 712                                 ? "none"
 713                                 : (field->type.u.basic.integer.encoding == lttng_encode_UTF8)
 714                                         ? "UTF8"
 715                                         : "ASCII",
 716                         field->type.u.basic.integer.base,
 717 #if (BYTE_ORDER == BIG_ENDIAN)
 718                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 719 #else
 720                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 721 #endif
 722                         field->name);
 723                 break;
 724         case atype_float:
 725                 ret = lttng_metadata_printf(session,
 726                         "               floating_point { exp_dig = %u; mant_dig = %u; align = %u;%s } _%s;\n",
 727                         field->type.u.basic._float.exp_dig,
 728                         field->type.u.basic._float.mant_dig,
 729                         field->type.u.basic._float.alignment,
 730 #if (BYTE_ORDER == BIG_ENDIAN)
 731                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 732 #else
 733                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 734 #endif
 735                         field->name);
 736                 break;
 737         case atype_enum:
 738                 ret = lttng_metadata_printf(session,
 739                         "               %s %s;\n",
 740                         field->type.u.basic.enumeration.name,
 741                         field->name);
 742                 break;
 743         case atype_array:
 744         {
 745                 const struct lttng_basic_type *elem_type;
 746
 747                 elem_type = &field->type.u.array.elem_type;
 748                 ret = lttng_metadata_printf(session,
 749                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[%u];\n",
 750                         elem_type->u.basic.integer.size,
 751                         elem_type->u.basic.integer.alignment,
 752                         elem_type->u.basic.integer.signedness,
 753                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 754                                 ? "none"
 755                                 : (elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 756                                         ? "UTF8"
 757                                         : "ASCII",
 758                         elem_type->u.basic.integer.base,
 759 #if (BYTE_ORDER == BIG_ENDIAN)
 760                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 761 #else
 762                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 763 #endif
 764                         field->name, field->type.u.array.length);
 765                 break;
 766         }
 767         case atype_sequence:
 768         {
 769                 const struct lttng_basic_type *elem_type;
 770                 const struct lttng_basic_type *length_type;
 771
 772                 elem_type = &field->type.u.sequence.elem_type;
 773                 length_type = &field->type.u.sequence.length_type;
 774                 ret = lttng_metadata_printf(session,
 775                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } __%s_length;\n",
 776                         length_type->u.basic.integer.size,
 777                         (unsigned int) length_type->u.basic.integer.alignment,
 778                         length_type->u.basic.integer.signedness,
 779                         (length_type->u.basic.integer.encoding == lttng_encode_none)
 780                                 ? "none"
 781                                 : ((length_type->u.basic.integer.encoding == lttng_encode_UTF8)
 782                                         ? "UTF8"
 783                                         : "ASCII"),
 784                         length_type->u.basic.integer.base,
 785 #if (BYTE_ORDER == BIG_ENDIAN)
 786                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 787 #else
 788                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 789 #endif
 790                         field->name);
 791                 if (ret)
 792                         return ret;
 793
 794                 ret = lttng_metadata_printf(session,
 795                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[ __%s_length ];\n",
 796                         elem_type->u.basic.integer.size,
 797                         (unsigned int) elem_type->u.basic.integer.alignment,
 798                         elem_type->u.basic.integer.signedness,
 799                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 800                                 ? "none"
 801                                 : ((elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 802                                         ? "UTF8"
 803                                         : "ASCII"),
 804                         elem_type->u.basic.integer.base,
 805 #if (BYTE_ORDER == BIG_ENDIAN)
 806                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 807 #else
 808                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 809 #endif
 810                         field->name,
 811                         field->name);
 812                 break;
 813         }
 814
 815         case atype_string:
 816                 /* Default encoding is UTF8 */
 817                 ret = lttng_metadata_printf(session,
 818                         "               string%s _%s;\n",
 819                         field->type.u.basic.string.encoding == lttng_encode_ASCII ?
 820                                 " { encoding = ASCII; }" : "",
 821                         field->name);
 822                 break;
 823         default:
 824                 WARN_ON_ONCE(1);
 825                 return -EINVAL;
 826         }
 827         return ret;
 828 }
 829
 830 static
 831 int _lttng_context_metadata_statedump(struct lttng_session *session,
 832                                     struct lttng_ctx *ctx)
 833 {
 834         int ret = 0;
 835         int i;
 836
 837         if (!ctx)
 838                 return 0;
 839         for (i = 0; i < ctx->nr_fields; i++) {
 840                 const struct lttng_ctx_field *field = &ctx->fields[i];
 841
 842                 ret = _lttng_field_statedump(session, &field->event_field);
 843                 if (ret)
 844                         return ret;
 845         }
 846         return ret;
 847 }
 848
 849 static
 850 int _lttng_fields_metadata_statedump(struct lttng_session *session,
 851                                    struct lttng_event *event)
 852 {
 853         const struct lttng_event_desc *desc = event->desc;
 854         int ret = 0;
 855         int i;
 856
 857         for (i = 0; i < desc->nr_fields; i++) {
 858                 const struct lttng_event_field *field = &desc->fields[i];
 859
 860                 ret = _lttng_field_statedump(session, field);
 861                 if (ret)
 862                         return ret;
 863         }
 864         return ret;
 865 }
 866
 867 static
 868 int _lttng_event_metadata_statedump(struct lttng_session *session,
 869                                   struct lttng_channel *chan,
 870                                   struct lttng_event *event)
 871 {
 872         int ret = 0;
 873         int loglevel = TRACE_DEFAULT;
 874
 875         if (event->metadata_dumped || !CMM_ACCESS_ONCE(session->active))
 876                 return 0;
 877         if (chan == session->metadata)
 878                 return 0;
 879         /*
 880          * Don't print events for which probe load is pending.
 881          */
 882         if (!event->desc)
 883                 return 0;
 884
 885         ret = lttng_metadata_printf(session,
 886                 "event {\n"
 887                 "       name = \"%s\";\n"
 888                 "       id = %u;\n"
 889                 "       stream_id = %u;\n",
 890                 event->desc->name,
 891                 event->id,
 892                 event->chan->id);
 893         if (ret)
 894                 goto end;
 895
 896         if (event->desc->loglevel)
 897                 loglevel = *(*event->desc->loglevel);
 898
 899         ret = lttng_metadata_printf(session,
 900                 "       loglevel = %d;\n",
 901                 loglevel);
 902         if (ret)
 903                 goto end;
 904
 905         if (event->desc->u.ext.model_emf_uri) {
 906                 ret = lttng_metadata_printf(session,
 907                         "       model.emf.uri = \"%s\";\n",
 908                         *(event->desc->u.ext.model_emf_uri));
 909                 if (ret)
 910                         goto end;
 911         }
 912
 913         if (event->ctx) {
 914                 ret = lttng_metadata_printf(session,
 915                         "       context := struct {\n");
 916                 if (ret)
 917                         goto end;
 918         }
 919         ret = _lttng_context_metadata_statedump(session, event->ctx);
 920         if (ret)
 921                 goto end;
 922         if (event->ctx) {
 923                 ret = lttng_metadata_printf(session,
 924                         "       };\n");
 925                 if (ret)
 926                         goto end;
 927         }
 928
 929         ret = lttng_metadata_printf(session,
 930                 "       fields := struct {\n"
 931                 );
 932         if (ret)
 933                 goto end;
 934
 935         ret = _lttng_fields_metadata_statedump(session, event);
 936         if (ret)
 937                 goto end;
 938
 939         /*
 940          * LTTng space reservation can only reserve multiples of the
 941          * byte size.
 942          */
 943         ret = lttng_metadata_printf(session,
 944                 "       };\n"
 945                 "};\n\n");
 946         if (ret)
 947                 goto end;
 948
 949         event->metadata_dumped = 1;
 950 end:
 951         return ret;
 952
 953 }
 954
 955 static
 956 int _lttng_channel_metadata_statedump(struct lttng_session *session,
 957                                     struct lttng_channel *chan)
 958 {
 959         int ret = 0;
 960
 961         if (chan->metadata_dumped || !CMM_ACCESS_ONCE(session->active))
 962                 return 0;
 963         if (chan == session->metadata)
 964                 return 0;
 965
 966         WARN_ON_ONCE(!chan->header_type);
 967         ret = lttng_metadata_printf(session,
 968                 "stream {\n"
 969                 "       id = %u;\n"
 970                 "       event.header := %s;\n"
 971                 "       packet.context := struct packet_context;\n",
 972                 chan->id,
 973                 chan->header_type == 1 ? "struct event_header_compact" :
 974                         "struct event_header_large");
 975         if (ret)
 976                 goto end;
 977
 978         if (chan->ctx) {
 979                 ret = lttng_metadata_printf(session,
 980                         "       event.context := struct {\n");
 981                 if (ret)
 982                         goto end;
 983         }
 984         ret = _lttng_context_metadata_statedump(session, chan->ctx);
 985         if (ret)
 986                 goto end;
 987         if (chan->ctx) {
 988                 ret = lttng_metadata_printf(session,
 989                         "       };\n");
 990                 if (ret)
 991                         goto end;
 992         }
 993
 994         ret = lttng_metadata_printf(session,
 995                 "};\n\n");
 996
 997         chan->metadata_dumped = 1;
 998 end:
 999         return ret;
1000 }
1001
1002 static
1003 int _lttng_stream_packet_context_declare(struct lttng_session *session)
1004 {
1005         return lttng_metadata_printf(session,
1006                 "struct packet_context {\n"
1007                 "       uint64_clock_monotonic_t timestamp_begin;\n"
1008                 "       uint64_clock_monotonic_t timestamp_end;\n"
1009                 "       uint64_t content_size;\n"
1010                 "       uint64_t packet_size;\n"
1011                 "       unsigned long events_discarded;\n"
1012                 "       uint32_t cpu_id;\n"
1013                 "};\n\n"
1014                 );
1015 }
1016
1017 /*
1018  * Compact header:
1019  * id: range: 0 - 30.
1020  * id 31 is reserved to indicate an extended header.
1021  *
1022  * Large header:
1023  * id: range: 0 - 65534.
1024  * id 65535 is reserved to indicate an extended header.
1025  */
1026 static
1027 int _lttng_event_header_declare(struct lttng_session *session)
1028 {
1029         return lttng_metadata_printf(session,
1030         "struct event_header_compact {\n"
1031         "       enum : uint5_t { compact = 0 ... 30, extended = 31 } id;\n"
1032         "       variant <id> {\n"
1033         "               struct {\n"
1034         "                       uint27_clock_monotonic_t timestamp;\n"
1035         "               } compact;\n"
1036         "               struct {\n"
1037         "                       uint32_t id;\n"
1038         "                       uint64_clock_monotonic_t timestamp;\n"
1039         "               } extended;\n"
1040         "       } v;\n"
1041         "} align(%u);\n"
1042         "\n"
1043         "struct event_header_large {\n"
1044         "       enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;\n"
1045         "       variant <id> {\n"
1046         "               struct {\n"
1047         "                       uint32_clock_monotonic_t timestamp;\n"
1048         "               } compact;\n"
1049         "               struct {\n"
1050         "                       uint32_t id;\n"
1051         "                       uint64_clock_monotonic_t timestamp;\n"
1052         "               } extended;\n"
1053         "       } v;\n"
1054         "} align(%u);\n\n",
1055         lttng_alignof(uint32_t) * CHAR_BIT,
1056         lttng_alignof(uint16_t) * CHAR_BIT
1057         );
1058 }
1059
1060 /*
1061  * Approximation of NTP time of day to clock monotonic correlation,
1062  * taken at start of trace.
1063  * Yes, this is only an approximation. Yes, we can (and will) do better
1064  * in future versions.
1065  */
1066 static
1067 uint64_t measure_clock_offset(void)
1068 {
1069         uint64_t offset, monotonic[2], realtime;
1070         struct timespec rts = { 0, 0 };
1071         int ret;
1072
1073         monotonic[0] = trace_clock_read64();
1074         ret = clock_gettime(CLOCK_REALTIME, &rts);
1075         if (ret < 0)
1076                 return 0;
1077         monotonic[1] = trace_clock_read64();
1078         offset = (monotonic[0] + monotonic[1]) >> 1;
1079         realtime = (uint64_t) rts.tv_sec * 1000000000ULL;
1080         realtime += rts.tv_nsec;
1081         offset = realtime - offset;
1082         return offset;
1083 }
1084
1085 /*
1086  * Output metadata into this session's metadata buffers.
1087  */
1088 static
1089 int _lttng_session_metadata_statedump(struct lttng_session *session)
1090 {
1091         unsigned char *uuid_c = session->uuid;
1092         char uuid_s[LTTNG_UST_UUID_STR_LEN],
1093                 clock_uuid_s[LTTNG_UST_UUID_STR_LEN];
1094         struct lttng_channel *chan;
1095         struct lttng_event *event;
1096         int ret = 0;
1097         char procname[LTTNG_UST_PROCNAME_LEN] = "";
1098         char hostname[HOST_NAME_MAX];
1099
1100         if (!CMM_ACCESS_ONCE(session->active))
1101                 return 0;
1102         if (session->metadata_dumped)
1103                 goto skip_session;
1104         if (!session->metadata) {
1105                 DBG("LTTng: attempt to start tracing, but metadata channel is not found. Operation abort.\n");
1106                 return -EPERM;
1107         }
1108
1109         snprintf(uuid_s, sizeof(uuid_s),
1110                 "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
1111                 uuid_c[0], uuid_c[1], uuid_c[2], uuid_c[3],
1112                 uuid_c[4], uuid_c[5], uuid_c[6], uuid_c[7],
1113                 uuid_c[8], uuid_c[9], uuid_c[10], uuid_c[11],
1114                 uuid_c[12], uuid_c[13], uuid_c[14], uuid_c[15]);
1115
1116         ret = lttng_metadata_printf(session,
1117                 "typealias integer { size = 8; align = %u; signed = false; } := uint8_t;\n"
1118                 "typealias integer { size = 16; align = %u; signed = false; } := uint16_t;\n"
1119                 "typealias integer { size = 32; align = %u; signed = false; } := uint32_t;\n"
1120                 "typealias integer { size = 64; align = %u; signed = false; } := uint64_t;\n"
1121                 "typealias integer { size = %u; align = %u; signed = false; } := unsigned long;\n"
1122                 "typealias integer { size = 5; align = 1; signed = false; } := uint5_t;\n"
1123                 "typealias integer { size = 27; align = 1; signed = false; } := uint27_t;\n"
1124                 "\n"
1125                 "trace {\n"
1126                 "       major = %u;\n"
1127                 "       minor = %u;\n"
1128                 "       uuid = \"%s\";\n"
1129                 "       byte_order = %s;\n"
1130                 "       packet.header := struct {\n"
1131                 "               uint32_t magic;\n"
1132                 "               uint8_t  uuid[16];\n"
1133                 "               uint32_t stream_id;\n"
1134                 "       };\n"
1135                 "};\n\n",
1136                 lttng_alignof(uint8_t) * CHAR_BIT,
1137                 lttng_alignof(uint16_t) * CHAR_BIT,
1138                 lttng_alignof(uint32_t) * CHAR_BIT,
1139                 lttng_alignof(uint64_t) * CHAR_BIT,
1140                 sizeof(unsigned long) * CHAR_BIT,
1141                 lttng_alignof(unsigned long) * CHAR_BIT,
1142                 CTF_SPEC_MAJOR,
1143                 CTF_SPEC_MINOR,
1144                 uuid_s,
1145 #if (BYTE_ORDER == BIG_ENDIAN)
1146                 "be"
1147 #else
1148                 "le"
1149 #endif
1150                 );
1151         if (ret)
1152                 goto end;
1153
1154         /* ignore error, just use empty string if error. */
1155         hostname[0] = '\0';
1156         ret = gethostname(hostname, sizeof(hostname));
1157         if (ret && errno == ENAMETOOLONG)
1158                 hostname[HOST_NAME_MAX - 1] = '\0';
1159         lttng_ust_getprocname(procname);
1160         procname[LTTNG_UST_PROCNAME_LEN - 1] = '\0';
1161         ret = lttng_metadata_printf(session,
1162                 "env {\n"
1163                 "       hostname = \"%s\";\n"
1164                 "       vpid = %d;\n"
1165                 "       procname = \"%s\";\n"
1166                 "       domain = \"ust\";\n"
1167                 "       tracer_name = \"lttng-ust\";\n"
1168                 "       tracer_major = %u;\n"
1169                 "       tracer_minor = %u;\n"
1170                 "       tracer_patchlevel = %u;\n"
1171                 "};\n\n",
1172                 hostname,
1173                 (int) getpid(),
1174                 procname,
1175                 LTTNG_UST_MAJOR_VERSION,
1176                 LTTNG_UST_MINOR_VERSION,
1177                 LTTNG_UST_PATCHLEVEL_VERSION
1178                 );
1179         if (ret)
1180                 goto end;
1181
1182         ret = lttng_metadata_printf(session,
1183                 "clock {\n"
1184                 "       name = %s;\n",
1185                 "monotonic"
1186                 );
1187         if (ret)
1188                 goto end;
1189
1190         if (!trace_clock_uuid(clock_uuid_s)) {
1191                 ret = lttng_metadata_printf(session,
1192                         "       uuid = \"%s\";\n",
1193                         clock_uuid_s
1194                         );
1195                 if (ret)
1196                         goto end;
1197         }
1198
1199         ret = lttng_metadata_printf(session,
1200                 "       description = \"Monotonic Clock\";\n"
1201                 "       freq = %" PRIu64 "; /* Frequency, in Hz */\n"
1202                 "       /* clock value offset from Epoch is: offset * (1/freq) */\n"
1203                 "       offset = %" PRIu64 ";\n"
1204                 "};\n\n",
1205                 trace_clock_freq(),
1206                 measure_clock_offset()
1207                 );
1208         if (ret)
1209                 goto end;
1210
1211         ret = lttng_metadata_printf(session,
1212                 "typealias integer {\n"
1213                 "       size = 27; align = 1; signed = false;\n"
1214                 "       map = clock.monotonic.value;\n"
1215                 "} := uint27_clock_monotonic_t;\n"
1216                 "\n"
1217                 "typealias integer {\n"
1218                 "       size = 32; align = %u; signed = false;\n"
1219                 "       map = clock.monotonic.value;\n"
1220                 "} := uint32_clock_monotonic_t;\n"
1221                 "\n"
1222                 "typealias integer {\n"
1223                 "       size = 64; align = %u; signed = false;\n"
1224                 "       map = clock.monotonic.value;\n"
1225                 "} := uint64_clock_monotonic_t;\n\n",
1226                 lttng_alignof(uint32_t) * CHAR_BIT,
1227                 lttng_alignof(uint64_t) * CHAR_BIT
1228                 );
1229         if (ret)
1230                 goto end;
1231
1232         ret = _lttng_stream_packet_context_declare(session);
1233         if (ret)
1234                 goto end;
1235
1236         ret = _lttng_event_header_declare(session);
1237         if (ret)
1238                 goto end;
1239
1240 skip_session:
1241         cds_list_for_each_entry(chan, &session->chan_head, node) {
1242                 ret = _lttng_channel_metadata_statedump(session, chan);
1243                 if (ret)
1244                         goto end;
1245         }
1246
1247         cds_list_for_each_entry(event, &session->events_head, node) {
1248                 ret = _lttng_event_metadata_statedump(session, event->chan, event);
1249                 if (ret)
1250                         goto end;
1251         }
1252         session->metadata_dumped = 1;
1253 end:
1254         return ret;
1255 }
1256
1257 void lttng_ust_events_exit(void)
1258 {
1259         struct lttng_session *session, *tmpsession;
1260
1261         cds_list_for_each_entry_safe(session, tmpsession, &sessions, node)
1262                 lttng_session_destroy(session);
1263 }
1264
1265 /*
1266  * Enabler management.
1267  */
1268 struct lttng_enabler *lttng_enabler_create(enum lttng_enabler_type type,
1269                 struct lttng_ust_event *event_param,
1270                 struct lttng_channel *chan)
1271 {
1272         struct lttng_enabler *enabler;
1273
1274         enabler = zmalloc(sizeof(*enabler));
1275         if (!enabler)
1276                 return NULL;
1277         enabler->type = type;
1278         CDS_INIT_LIST_HEAD(&enabler->filter_bytecode_head);
1279         memcpy(&enabler->event_param, event_param,
1280                 sizeof(enabler->event_param));
1281         enabler->chan = chan;
1282         /* ctx left NULL */
1283         enabler->enabled = 1;
1284         cds_list_add(&enabler->node, &enabler->chan->session->enablers_head);
1285         lttng_session_lazy_sync_enablers(enabler->chan->session);
1286         return enabler;
1287 }
1288
1289 int lttng_enabler_enable(struct lttng_enabler *enabler)
1290 {
1291         enabler->enabled = 1;
1292         lttng_session_lazy_sync_enablers(enabler->chan->session);
1293         return 0;
1294 }
1295
1296 int lttng_enabler_disable(struct lttng_enabler *enabler)
1297 {
1298         if (enabler->chan == enabler->chan->session->metadata)
1299                 return -EPERM;
1300         enabler->enabled = 0;
1301         lttng_session_lazy_sync_enablers(enabler->chan->session);
1302         return 0;
1303 }
1304
1305 int lttng_enabler_attach_bytecode(struct lttng_enabler *enabler,
1306                 struct lttng_ust_filter_bytecode_node *bytecode)
1307 {
1308         bytecode->enabler = enabler;
1309         cds_list_add_tail(&bytecode->node, &enabler->filter_bytecode_head);
1310         lttng_session_lazy_sync_enablers(enabler->chan->session);
1311         return 0;
1312 }
1313
1314 int lttng_attach_context(struct lttng_ust_context *context_param,
1315                 struct lttng_ctx **ctx, struct lttng_session *session)
1316 {
1317         /*
1318          * We cannot attach a context after trace has been started for a
1319          * session because the metadata does not allow expressing this
1320          * information outside of the original channel scope.
1321          */
1322         if (session->been_active)
1323                 return -EPERM;
1324
1325         switch (context_param->ctx) {
1326         case LTTNG_UST_CONTEXT_PTHREAD_ID:
1327                 return lttng_add_pthread_id_to_ctx(ctx);
1328         case LTTNG_UST_CONTEXT_VTID:
1329                 return lttng_add_vtid_to_ctx(ctx);
1330         case LTTNG_UST_CONTEXT_VPID:
1331                 return lttng_add_vpid_to_ctx(ctx);
1332         case LTTNG_UST_CONTEXT_PROCNAME:
1333                 return lttng_add_procname_to_ctx(ctx);
1334         default:
1335                 return -EINVAL;
1336         }
1337 }
1338
1339 int lttng_enabler_attach_context(struct lttng_enabler *enabler,
1340                 struct lttng_ust_context *context_param)
1341 {
1342 #if 0   // disabled for now.
1343         struct lttng_session *session = enabler->chan->session;
1344         int ret;
1345
1346         ret = lttng_attach_context(context_param, &enabler->ctx,
1347                         session);
1348         if (ret)
1349                 return ret;
1350         lttng_session_lazy_sync_enablers(enabler->chan->session);
1351 #endif
1352         return -ENOSYS;
1353 }
1354
1355 static
1356 void lttng_enabler_destroy(struct lttng_enabler *enabler)
1357 {
1358         struct lttng_ust_filter_bytecode_node *filter_node, *tmp_filter_node;
1359
1360         /* Destroy filter bytecode */
1361         cds_list_for_each_entry_safe(filter_node, tmp_filter_node,
1362                         &enabler->filter_bytecode_head, node) {
1363                 free(filter_node);
1364         }
1365
1366         /* Destroy contexts */
1367         lttng_destroy_context(enabler->ctx);
1368
1369         cds_list_del(&enabler->node);
1370         free(enabler);
1371 }
1372
1373 /*
1374  * lttng_session_sync_enablers should be called just before starting a
1375  * session.
1376  */
1377 static
1378 void lttng_session_sync_enablers(struct lttng_session *session)
1379 {
1380         struct lttng_enabler *enabler;
1381         struct lttng_event *event;
1382
1383         cds_list_for_each_entry(enabler, &session->enablers_head, node)
1384                 lttng_enabler_ref_events(enabler);
1385         /*
1386          * For each event, if at least one of its enablers is enabled,
1387          * we enable the event, else we disable it.
1388          */
1389         cds_list_for_each_entry(event, &session->events_head, node) {
1390                 struct lttng_enabler_ref *enabler_ref;
1391                 struct lttng_bytecode_runtime *runtime;
1392                 int enabled = 0, has_enablers_without_bytecode = 0;
1393
1394                 /* Enable events */
1395                 cds_list_for_each_entry(enabler_ref,
1396                                 &event->enablers_ref_head, node) {
1397                         if (enabler_ref->ref->enabled) {
1398                                 enabled = 1;
1399                                 break;
1400                         }
1401                 }
1402                 event->enabled = enabled;
1403
1404                 /* Check if has enablers without bytecode enabled */
1405                 cds_list_for_each_entry(enabler_ref,
1406                                 &event->enablers_ref_head, node) {
1407                         if (enabler_ref->ref->enabled
1408                                         && cds_list_empty(&enabler_ref->ref->filter_bytecode_head)) {
1409                                 has_enablers_without_bytecode = 1;
1410                                 break;
1411                         }
1412                 }
1413                 event->has_enablers_without_bytecode =
1414                         has_enablers_without_bytecode;
1415
1416                 /* Enable filters */
1417                 cds_list_for_each_entry(runtime,
1418                                 &event->bytecode_runtime_head, node) {
1419                         lttng_filter_sync_state(runtime);
1420                 }
1421         }
1422 }
1423
1424 /*
1425  * Apply enablers to session events, adding events to session if need
1426  * be. It is required after each modification applied to an active
1427  * session, and right before session "start".
1428  * "lazy" sync means we only sync if required.
1429  */
1430 static
1431 void lttng_session_lazy_sync_enablers(struct lttng_session *session)
1432 {
1433         /* We can skip if session is not active */
1434         if (!session->active)
1435                 return;
1436         lttng_session_sync_enablers(session);
1437 }
1438
1439 /*
1440  * Take the TLS "fault" in libuuid if dlopen'd, which can take the
1441  * dynamic linker mutex, outside of the UST lock, since the UST lock is
1442  * taken in constructors, which are called with dynamic linker mutex
1443  * held.
1444  */
1445 void lttng_fixup_event_tls(void)
1446 {
1447         unsigned char uuid[LTTNG_UST_UUID_STR_LEN];
1448
1449         (void) lttng_ust_uuid_generate(uuid);
1450 }