liblttng-ust/ltt-events.c

   1 /*
   2  * ltt-events.c
   3  *
   4  * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * Holds LTTng per-session event registry.
   7  *
   8  * Dual LGPL v2.1/GPL v2 license.
   9  */
  10
  11 #define _GNU_SOURCE
  12 #include <stdio.h>
  13 #include <endian.h>
  14 #include <urcu/list.h>
  15 #include <urcu/hlist.h>
  16 #include <pthread.h>
  17 #include <uuid/uuid.h>
  18 #include <errno.h>
  19 #include <sys/shm.h>
  20 #include <sys/ipc.h>
  21 #include <stdint.h>
  22 #include <stddef.h>
  23 #include <inttypes.h>
  24 #include <time.h>
  25 #include "clock.h"
  26
  27 #include <urcu-bp.h>
  28 #include <urcu/compiler.h>
  29 #include <urcu/uatomic.h>
  30 #include <urcu/arch.h>
  31
  32 #include <lttng/tracepoint.h>
  33 #include <lttng/ust-events.h>
  34
  35 #include <usterr-signal-safe.h>
  36 #include <helper.h>
  37 #include "error.h"
  38
  39 #include "tracepoint-internal.h"
  40 #include "ltt-tracer.h"
  41 #include "ltt-tracer-core.h"
  42 #include "wait.h"
  43 #include "../libringbuffer/shm.h"
  44 #include "jhash.h"
  45
  46 /*
  47  * The sessions mutex is the centralized mutex across UST tracing
  48  * control and probe registration. All operations within this file are
  49  * called by the communication thread, under ust_lock protection.
  50  */
  51 static pthread_mutex_t sessions_mutex = PTHREAD_MUTEX_INITIALIZER;
  52
  53 void ust_lock(void)
  54 {
  55         pthread_mutex_lock(&sessions_mutex);
  56 }
  57
  58 void ust_unlock(void)
  59 {
  60         pthread_mutex_unlock(&sessions_mutex);
  61 }
  62
  63 static CDS_LIST_HEAD(sessions);
  64
  65 /*
  66  * Wildcard list, containing the active wildcards.
  67  * Protected by ust lock.
  68  */
  69 static CDS_LIST_HEAD(wildcard_list);
  70
  71 /*
  72  * Pending probes hash table, containing the registered ltt events for
  73  * which tracepoint probes are still missing. Protected by the sessions
  74  * mutex.
  75  */
  76 #define PENDING_PROBE_HASH_BITS         6
  77 #define PENDING_PROBE_HASH_SIZE         (1 << PENDING_PROBE_HASH_BITS)
  78 static struct cds_hlist_head pending_probe_table[PENDING_PROBE_HASH_SIZE];
  79
  80 struct ust_pending_probe {
  81         struct ltt_event *event;
  82         struct cds_hlist_node node;
  83         enum lttng_ust_loglevel_type loglevel_type;
  84         int loglevel;
  85         char name[];
  86 };
  87
  88 static void _ltt_event_destroy(struct ltt_event *event);
  89 static void _ltt_wildcard_destroy(struct session_wildcard *sw);
  90 static void _ltt_channel_destroy(struct ltt_channel *chan);
  91 static int _ltt_event_unregister(struct ltt_event *event);
  92 static
  93 int _ltt_event_metadata_statedump(struct ltt_session *session,
  94                                   struct ltt_channel *chan,
  95                                   struct ltt_event *event);
  96 static
  97 int _ltt_session_metadata_statedump(struct ltt_session *session);
  98
  99 int ltt_loglevel_match(const struct lttng_event_desc *desc,
 100                 enum lttng_ust_loglevel_type req_type,
 101                 int req_loglevel)
 102 {
 103         int ev_loglevel;
 104
 105         if (req_type == LTTNG_UST_LOGLEVEL_ALL)
 106                 return 1;
 107         if (!desc->loglevel)
 108                 ev_loglevel = TRACE_DEFAULT;
 109         else
 110                 ev_loglevel = *(*desc->loglevel);
 111         switch (req_type) {
 112         case LTTNG_UST_LOGLEVEL_RANGE:
 113                 if (ev_loglevel <= req_loglevel || req_loglevel == -1)
 114                         return 1;
 115                 else
 116                         return 0;
 117         case LTTNG_UST_LOGLEVEL_SINGLE:
 118                 if (ev_loglevel == req_loglevel || req_loglevel == -1)
 119                         return 1;
 120                 else
 121                         return 0;
 122         case LTTNG_UST_LOGLEVEL_ALL:
 123         default:
 124                 return 1;
 125         }
 126 }
 127
 128 /*
 129  * Return wildcard for a given event name if the event name match the
 130  * one of the wildcards.
 131  * Must be called with ust lock held.
 132  * Returns NULL if not present.
 133  */
 134 static
 135 struct wildcard_entry *match_wildcard(const struct lttng_event_desc *desc)
 136 {
 137         struct wildcard_entry *e;
 138
 139         cds_list_for_each_entry(e, &wildcard_list, list) {
 140                 /* If only contain '*' */
 141                 if (strlen(e->name) == 1)
 142                         goto possible_match;
 143                 /* Compare excluding final '*' */
 144                 if (!strncmp(desc->name, e->name, strlen(e->name) - 1))
 145                         goto possible_match;
 146                 continue;       /* goto next, no match */
 147         possible_match:
 148                 if (ltt_loglevel_match(desc,
 149                                 e->loglevel_type,
 150                                 e->loglevel)) {
 151                         return e;
 152                 }
 153                 /* no match, loop to next */
 154         }
 155         return NULL;
 156 }
 157
 158 /*
 159  * called at event creation if probe is missing.
 160  * called with session mutex held.
 161  */
 162 static
 163 int add_pending_probe(struct ltt_event *event, const char *name,
 164                 enum lttng_ust_loglevel_type loglevel_type,
 165                 int loglevel)
 166 {
 167         struct cds_hlist_head *head;
 168         struct ust_pending_probe *e;
 169         size_t name_len = strlen(name);
 170         uint32_t hash;
 171
 172         if (name_len > LTTNG_UST_SYM_NAME_LEN - 1) {
 173                 WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_SYM_NAME_LEN - 1);
 174                 name_len = LTTNG_UST_SYM_NAME_LEN - 1;
 175         }
 176         hash = jhash(name, name_len, 0);
 177         head = &pending_probe_table[hash & (PENDING_PROBE_HASH_SIZE - 1)];
 178         e = zmalloc(sizeof(struct ust_pending_probe) + name_len);
 179         if (!e)
 180                 return -ENOMEM;
 181         memcpy(&e->name[0], name, name_len + 1);
 182         e->name[name_len] = '\0';
 183         e->loglevel_type = loglevel_type;
 184         e->loglevel = loglevel;
 185         cds_hlist_add_head(&e->node, head);
 186         e->event = event;
 187         event->pending_probe = e;
 188         return 0;
 189 }
 190
 191 /*
 192  * remove a pending probe. called when at event teardown and when an
 193  * event is fixed (probe is loaded).
 194  * called with session mutex held.
 195  */
 196 static
 197 void remove_pending_probe(struct ust_pending_probe *e)
 198 {
 199         if (!e)
 200                 return;
 201         cds_hlist_del(&e->node);
 202         free(e);
 203 }
 204
 205 /*
 206  * Called at library load: connect the probe on the events pending on
 207  * probe load.
 208  * called with session mutex held.
 209  */
 210 int pending_probe_fix_events(const struct lttng_event_desc *desc)
 211 {
 212         struct cds_hlist_head *head;
 213         struct cds_hlist_node *node, *p;
 214         struct ust_pending_probe *e;
 215         const char *name = desc->name;
 216         int ret = 0;
 217         struct lttng_ust_event event_param;
 218         size_t name_len = strlen(name);
 219         uint32_t hash;
 220
 221         /* Wildcard */
 222         {
 223                 struct wildcard_entry *wildcard;
 224
 225                 wildcard = match_wildcard(desc);
 226                 if (strcmp(desc->name, "lttng_ust:metadata") && wildcard) {
 227                         struct session_wildcard *sw;
 228
 229                         cds_list_for_each_entry(sw, &wildcard->session_list,
 230                                         session_list) {
 231                                 struct ltt_event *ev;
 232                                 int ret;
 233
 234                                 memcpy(&event_param, &sw->event_param,
 235                                                 sizeof(event_param));
 236                                 memcpy(event_param.name,
 237                                         desc->name,
 238                                         sizeof(event_param.name));
 239                                 /* create event */
 240                                 ret = ltt_event_create(sw->chan,
 241                                         &event_param, NULL,
 242                                         &ev);
 243                                 if (ret) {
 244                                         DBG("Error creating event");
 245                                         continue;
 246                                 }
 247                                 cds_list_add(&ev->wildcard_list,
 248                                         &sw->events);
 249                         }
 250                 }
 251         }
 252
 253         if (name_len > LTTNG_UST_SYM_NAME_LEN - 1) {
 254                 WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_SYM_NAME_LEN - 1);
 255                 name_len = LTTNG_UST_SYM_NAME_LEN - 1;
 256         }
 257         hash = jhash(name, name_len, 0);
 258         head = &pending_probe_table[hash & (PENDING_PROBE_HASH_SIZE - 1)];
 259         cds_hlist_for_each_entry_safe(e, node, p, head, node) {
 260                 struct ltt_event *event;
 261                 struct ltt_channel *chan;
 262
 263                 if (!ltt_loglevel_match(desc,
 264                                 e->loglevel_type,
 265                                 e->loglevel)) {
 266                         continue;
 267                 }
 268                 if (strncmp(name, e->name, LTTNG_UST_SYM_NAME_LEN - 1)) {
 269                         continue;
 270                 }
 271                 event = e->event;
 272                 chan = event->chan;
 273                 assert(!event->desc);
 274                 event->desc = desc;
 275                 event->pending_probe = NULL;
 276                 remove_pending_probe(e);
 277                 ret |= __tracepoint_probe_register(name,
 278                                 event->desc->probe_callback,
 279                                 event);
 280                 if (ret)
 281                         continue;
 282                 event->id = chan->free_event_id++;
 283                 ret |= _ltt_event_metadata_statedump(chan->session, chan,
 284                                 event);
 285         }
 286         return ret;
 287 }
 288
 289 void synchronize_trace(void)
 290 {
 291         synchronize_rcu();
 292 }
 293
 294 struct ltt_session *ltt_session_create(void)
 295 {
 296         struct ltt_session *session;
 297
 298         session = zmalloc(sizeof(struct ltt_session));
 299         if (!session)
 300                 return NULL;
 301         CDS_INIT_LIST_HEAD(&session->chan);
 302         CDS_INIT_LIST_HEAD(&session->events);
 303         CDS_INIT_LIST_HEAD(&session->wildcards);
 304         uuid_generate(session->uuid);
 305         cds_list_add(&session->list, &sessions);
 306         return session;
 307 }
 308
 309 void ltt_session_destroy(struct ltt_session *session)
 310 {
 311         struct ltt_channel *chan, *tmpchan;
 312         struct ltt_event *event, *tmpevent;
 313         struct session_wildcard *wildcard, *tmpwildcard;
 314         int ret;
 315
 316         CMM_ACCESS_ONCE(session->active) = 0;
 317         cds_list_for_each_entry(event, &session->events, list) {
 318                 ret = _ltt_event_unregister(event);
 319                 WARN_ON(ret);
 320         }
 321         synchronize_trace();    /* Wait for in-flight events to complete */
 322         cds_list_for_each_entry_safe(wildcard, tmpwildcard, &session->wildcards, list)
 323                 _ltt_wildcard_destroy(wildcard);
 324         cds_list_for_each_entry_safe(event, tmpevent, &session->events, list)
 325                 _ltt_event_destroy(event);
 326         cds_list_for_each_entry_safe(chan, tmpchan, &session->chan, list)
 327                 _ltt_channel_destroy(chan);
 328         cds_list_del(&session->list);
 329         free(session);
 330 }
 331
 332 int ltt_session_enable(struct ltt_session *session)
 333 {
 334         int ret = 0;
 335         struct ltt_channel *chan;
 336
 337         if (session->active) {
 338                 ret = -EBUSY;
 339                 goto end;
 340         }
 341
 342         /*
 343          * Snapshot the number of events per channel to know the type of header
 344          * we need to use.
 345          */
 346         cds_list_for_each_entry(chan, &session->chan, list) {
 347                 if (chan->header_type)
 348                         continue;               /* don't change it if session stop/restart */
 349                 if (chan->free_event_id < 31)
 350                         chan->header_type = 1;  /* compact */
 351                 else
 352                         chan->header_type = 2;  /* large */
 353         }
 354
 355         CMM_ACCESS_ONCE(session->active) = 1;
 356         CMM_ACCESS_ONCE(session->been_active) = 1;
 357         ret = _ltt_session_metadata_statedump(session);
 358         if (ret)
 359                 CMM_ACCESS_ONCE(session->active) = 0;
 360 end:
 361         return ret;
 362 }
 363
 364 int ltt_session_disable(struct ltt_session *session)
 365 {
 366         int ret = 0;
 367
 368         if (!session->active) {
 369                 ret = -EBUSY;
 370                 goto end;
 371         }
 372         CMM_ACCESS_ONCE(session->active) = 0;
 373 end:
 374         return ret;
 375 }
 376
 377 int ltt_channel_enable(struct ltt_channel *channel)
 378 {
 379         int old;
 380
 381         if (channel == channel->session->metadata)
 382                 return -EPERM;
 383         old = uatomic_xchg(&channel->enabled, 1);
 384         if (old)
 385                 return -EEXIST;
 386         return 0;
 387 }
 388
 389 int ltt_channel_disable(struct ltt_channel *channel)
 390 {
 391         int old;
 392
 393         if (channel == channel->session->metadata)
 394                 return -EPERM;
 395         old = uatomic_xchg(&channel->enabled, 0);
 396         if (!old)
 397                 return -EEXIST;
 398         return 0;
 399 }
 400
 401 int ltt_event_enable(struct ltt_event *event)
 402 {
 403         int old;
 404
 405         if (event->chan == event->chan->session->metadata)
 406                 return -EPERM;
 407         old = uatomic_xchg(&event->enabled, 1);
 408         if (old)
 409                 return -EEXIST;
 410         return 0;
 411 }
 412
 413 int ltt_event_disable(struct ltt_event *event)
 414 {
 415         int old;
 416
 417         if (event->chan == event->chan->session->metadata)
 418                 return -EPERM;
 419         old = uatomic_xchg(&event->enabled, 0);
 420         if (!old)
 421                 return -EEXIST;
 422         return 0;
 423 }
 424
 425 struct ltt_channel *ltt_channel_create(struct ltt_session *session,
 426                                        const char *transport_name,
 427                                        void *buf_addr,
 428                                        size_t subbuf_size, size_t num_subbuf,
 429                                        unsigned int switch_timer_interval,
 430                                        unsigned int read_timer_interval,
 431                                        int **shm_fd, int **wait_fd,
 432                                        uint64_t **memory_map_size,
 433                                        struct ltt_channel *chan_priv_init)
 434 {
 435         struct ltt_channel *chan = NULL;
 436         struct ltt_transport *transport;
 437
 438         if (session->been_active)
 439                 goto active;    /* Refuse to add channel to active session */
 440         transport = ltt_transport_find(transport_name);
 441         if (!transport) {
 442                 DBG("LTTng transport %s not found\n",
 443                        transport_name);
 444                 goto notransport;
 445         }
 446         chan_priv_init->id = session->free_chan_id++;
 447         chan_priv_init->session = session;
 448         /*
 449          * Note: the channel creation op already writes into the packet
 450          * headers. Therefore the "chan" information used as input
 451          * should be already accessible.
 452          */
 453         chan = transport->ops.channel_create("[lttng]", buf_addr,
 454                         subbuf_size, num_subbuf, switch_timer_interval,
 455                         read_timer_interval, shm_fd, wait_fd,
 456                         memory_map_size, chan_priv_init);
 457         if (!chan)
 458                 goto create_error;
 459         chan->enabled = 1;
 460         chan->ops = &transport->ops;
 461         cds_list_add(&chan->list, &session->chan);
 462         return chan;
 463
 464 create_error:
 465 notransport:
 466 active:
 467         return NULL;
 468 }
 469
 470 /*
 471  * Only used internally at session destruction.
 472  */
 473 static
 474 void _ltt_channel_destroy(struct ltt_channel *chan)
 475 {
 476         cds_list_del(&chan->list);
 477         lttng_destroy_context(chan->ctx);
 478         chan->ops->channel_destroy(chan);
 479 }
 480
 481 /*
 482  * Supports event creation while tracing session is active.
 483  */
 484 int ltt_event_create(struct ltt_channel *chan,
 485                 struct lttng_ust_event *event_param,
 486                 void *filter,
 487                 struct ltt_event **_event)
 488 {
 489         const struct lttng_event_desc *desc = NULL;     /* silence gcc */
 490         struct ltt_event *event;
 491         int ret = 0;
 492
 493         if (chan->used_event_id == -1UL) {
 494                 ret = -ENOMEM;
 495                 goto full;
 496         }
 497         /*
 498          * This is O(n^2) (for each event, the loop is called at event
 499          * creation). Might require a hash if we have lots of events.
 500          */
 501         cds_list_for_each_entry(event, &chan->session->events, list) {
 502                 if (event->desc && !strncmp(event->desc->name,
 503                                 event_param->name,
 504                                 LTTNG_UST_SYM_NAME_LEN - 1)) {
 505                         ret = -EEXIST;
 506                         goto exist;
 507                 }
 508         }
 509
 510         /*
 511          * Check if loglevel match. Refuse to connect event if not.
 512          */
 513         if (event_param->instrumentation == LTTNG_UST_TRACEPOINT) {
 514                 desc = ltt_event_get(event_param->name);
 515                 if (desc) {
 516                         if (!ltt_loglevel_match(desc,
 517                                         event_param->loglevel_type,
 518                                         event_param->loglevel)) {
 519                                 ret = -EPERM;
 520                                 goto no_loglevel_match;
 521                         }
 522                 }
 523                 /*
 524                  * If descriptor is not there, it will be added to
 525                  * pending probes.
 526                  */
 527         }
 528         event = zmalloc(sizeof(struct ltt_event));
 529         if (!event) {
 530                 ret = -ENOMEM;
 531                 goto cache_error;
 532         }
 533         event->chan = chan;
 534         event->filter = filter;
 535         /*
 536          * used_event_id counts the maximum number of event IDs that can
 537          * register if all probes register.
 538          */
 539         chan->used_event_id++;
 540         event->enabled = 1;
 541         event->instrumentation = event_param->instrumentation;
 542         /* Populate ltt_event structure before tracepoint registration. */
 543         cmm_smp_wmb();
 544         switch (event_param->instrumentation) {
 545         case LTTNG_UST_TRACEPOINT:
 546                 event->desc = desc;
 547                 if (event->desc) {
 548                         ret = __tracepoint_probe_register(event_param->name,
 549                                         event->desc->probe_callback,
 550                                         event);
 551                         if (ret)
 552                                 goto register_error;
 553                         event->id = chan->free_event_id++;
 554                 } else {
 555                         /*
 556                          * If the probe is not present, event->desc stays NULL,
 557                          * waiting for the probe to register, and the event->id
 558                          * stays unallocated.
 559                          */
 560                         ret = add_pending_probe(event, event_param->name,
 561                                         event_param->loglevel_type,
 562                                         event_param->loglevel);
 563                         if (ret)
 564                                 goto add_pending_error;
 565                 }
 566                 break;
 567         default:
 568                 WARN_ON_ONCE(1);
 569         }
 570         if (event->desc) {
 571                 ret = _ltt_event_metadata_statedump(chan->session, chan, event);
 572                 if (ret)
 573                         goto statedump_error;
 574         }
 575         cds_list_add(&event->list, &chan->session->events);
 576         *_event = event;
 577         return 0;
 578
 579 statedump_error:
 580         if (event->desc) {
 581                 WARN_ON_ONCE(__tracepoint_probe_unregister(event_param->name,
 582                                         event->desc->probe_callback,
 583                                         event));
 584                 ltt_event_put(event->desc);
 585         }
 586 add_pending_error:
 587 register_error:
 588         free(event);
 589 cache_error:
 590 no_loglevel_match:
 591 exist:
 592 full:
 593         return ret;
 594 }
 595
 596 /*
 597  * Only used internally at session destruction.
 598  */
 599 int _ltt_event_unregister(struct ltt_event *event)
 600 {
 601         int ret = -EINVAL;
 602
 603         switch (event->instrumentation) {
 604         case LTTNG_UST_TRACEPOINT:
 605                 if (event->desc) {
 606                         ret = __tracepoint_probe_unregister(event->desc->name,
 607                                                           event->desc->probe_callback,
 608                                                           event);
 609                         if (ret)
 610                                 return ret;
 611                 } else {
 612                         remove_pending_probe(event->pending_probe);
 613                         ret = 0;
 614                 }
 615                 break;
 616         default:
 617                 WARN_ON_ONCE(1);
 618         }
 619         return ret;
 620 }
 621
 622 /*
 623  * Only used internally at session destruction.
 624  */
 625 static
 626 void _ltt_event_destroy(struct ltt_event *event)
 627 {
 628         switch (event->instrumentation) {
 629         case LTTNG_UST_TRACEPOINT:
 630                 if (event->desc) {
 631                         ltt_event_put(event->desc);
 632                 }
 633                 break;
 634         default:
 635                 WARN_ON_ONCE(1);
 636         }
 637         cds_list_del(&event->list);
 638         lttng_destroy_context(event->ctx);
 639         free(event);
 640 }
 641
 642 /*
 643  * We have exclusive access to our metadata buffer (protected by the
 644  * ust_lock), so we can do racy operations such as looking for
 645  * remaining space left in packet and write, since mutual exclusion
 646  * protects us from concurrent writes.
 647  */
 648 int lttng_metadata_printf(struct ltt_session *session,
 649                           const char *fmt, ...)
 650 {
 651         struct lttng_ust_lib_ring_buffer_ctx ctx;
 652         struct ltt_channel *chan = session->metadata;
 653         char *str = NULL;
 654         int ret = 0, waitret;
 655         size_t len, reserve_len, pos;
 656         va_list ap;
 657
 658         WARN_ON_ONCE(!CMM_ACCESS_ONCE(session->active));
 659
 660         va_start(ap, fmt);
 661         ret = vasprintf(&str, fmt, ap);
 662         va_end(ap);
 663         if (ret < 0)
 664                 return -ENOMEM;
 665
 666         len = strlen(str);
 667         pos = 0;
 668
 669         for (pos = 0; pos < len; pos += reserve_len) {
 670                 reserve_len = min_t(size_t,
 671                                 chan->ops->packet_avail_size(chan->chan, chan->handle),
 672                                 len - pos);
 673                 lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL, reserve_len,
 674                                          sizeof(char), -1, chan->handle);
 675                 /*
 676                  * We don't care about metadata buffer's records lost
 677                  * count, because we always retry here. Report error if
 678                  * we need to bail out after timeout or being
 679                  * interrupted.
 680                  */
 681                 waitret = wait_cond_interruptible_timeout(
 682                         ({
 683                                 ret = chan->ops->event_reserve(&ctx, 0);
 684                                 ret != -ENOBUFS || !ret;
 685                         }),
 686                         LTTNG_METADATA_TIMEOUT_MSEC);
 687                 if (waitret == -ETIMEDOUT || waitret == -EINTR || ret) {
 688                         DBG("LTTng: Failure to write metadata to buffers (%s)\n",
 689                                 waitret == -EINTR ? "interrupted" :
 690                                         (ret == -ENOBUFS ? "timeout" : "I/O error"));
 691                         if (waitret == -EINTR)
 692                                 ret = waitret;
 693                         goto end;
 694                 }
 695                 chan->ops->event_write(&ctx, &str[pos], reserve_len);
 696                 chan->ops->event_commit(&ctx);
 697         }
 698 end:
 699         free(str);
 700         return ret;
 701 }
 702
 703 static
 704 int _ltt_field_statedump(struct ltt_session *session,
 705                          const struct lttng_event_field *field)
 706 {
 707         int ret = 0;
 708
 709         switch (field->type.atype) {
 710         case atype_integer:
 711                 ret = lttng_metadata_printf(session,
 712                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s;\n",
 713                         field->type.u.basic.integer.size,
 714                         field->type.u.basic.integer.alignment,
 715                         field->type.u.basic.integer.signedness,
 716                         (field->type.u.basic.integer.encoding == lttng_encode_none)
 717                                 ? "none"
 718                                 : (field->type.u.basic.integer.encoding == lttng_encode_UTF8)
 719                                         ? "UTF8"
 720                                         : "ASCII",
 721                         field->type.u.basic.integer.base,
 722 #if (BYTE_ORDER == BIG_ENDIAN)
 723                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 724 #else
 725                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 726 #endif
 727                         field->name);
 728                 break;
 729         case atype_float:
 730                 ret = lttng_metadata_printf(session,
 731                         "               floating_point { exp_dig = %u; mant_dig = %u; align = %u;%s } _%s;\n",
 732                         field->type.u.basic._float.exp_dig,
 733                         field->type.u.basic._float.mant_dig,
 734                         field->type.u.basic._float.alignment,
 735 #if (BYTE_ORDER == BIG_ENDIAN)
 736                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 737 #else
 738                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 739 #endif
 740                         field->name);
 741                 break;
 742         case atype_enum:
 743                 ret = lttng_metadata_printf(session,
 744                         "               %s %s;\n",
 745                         field->type.u.basic.enumeration.name,
 746                         field->name);
 747                 break;
 748         case atype_array:
 749         {
 750                 const struct lttng_basic_type *elem_type;
 751
 752                 elem_type = &field->type.u.array.elem_type;
 753                 ret = lttng_metadata_printf(session,
 754                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[%u];\n",
 755                         elem_type->u.basic.integer.size,
 756                         elem_type->u.basic.integer.alignment,
 757                         elem_type->u.basic.integer.signedness,
 758                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 759                                 ? "none"
 760                                 : (elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 761                                         ? "UTF8"
 762                                         : "ASCII",
 763                         elem_type->u.basic.integer.base,
 764 #if (BYTE_ORDER == BIG_ENDIAN)
 765                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 766 #else
 767                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 768 #endif
 769                         field->name, field->type.u.array.length);
 770                 break;
 771         }
 772         case atype_sequence:
 773         {
 774                 const struct lttng_basic_type *elem_type;
 775                 const struct lttng_basic_type *length_type;
 776
 777                 elem_type = &field->type.u.sequence.elem_type;
 778                 length_type = &field->type.u.sequence.length_type;
 779                 ret = lttng_metadata_printf(session,
 780                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } __%s_length;\n",
 781                         length_type->u.basic.integer.size,
 782                         (unsigned int) length_type->u.basic.integer.alignment,
 783                         length_type->u.basic.integer.signedness,
 784                         (length_type->u.basic.integer.encoding == lttng_encode_none)
 785                                 ? "none"
 786                                 : ((length_type->u.basic.integer.encoding == lttng_encode_UTF8)
 787                                         ? "UTF8"
 788                                         : "ASCII"),
 789                         length_type->u.basic.integer.base,
 790 #if (BYTE_ORDER == BIG_ENDIAN)
 791                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 792 #else
 793                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 794 #endif
 795                         field->name);
 796                 if (ret)
 797                         return ret;
 798
 799                 ret = lttng_metadata_printf(session,
 800                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[ __%s_length ];\n",
 801                         elem_type->u.basic.integer.size,
 802                         (unsigned int) elem_type->u.basic.integer.alignment,
 803                         elem_type->u.basic.integer.signedness,
 804                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 805                                 ? "none"
 806                                 : ((elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 807                                         ? "UTF8"
 808                                         : "ASCII"),
 809                         elem_type->u.basic.integer.base,
 810 #if (BYTE_ORDER == BIG_ENDIAN)
 811                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 812 #else
 813                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 814 #endif
 815                         field->name,
 816                         field->name);
 817                 break;
 818         }
 819
 820         case atype_string:
 821                 /* Default encoding is UTF8 */
 822                 ret = lttng_metadata_printf(session,
 823                         "               string%s _%s;\n",
 824                         field->type.u.basic.string.encoding == lttng_encode_ASCII ?
 825                                 " { encoding = ASCII; }" : "",
 826                         field->name);
 827                 break;
 828         default:
 829                 WARN_ON_ONCE(1);
 830                 return -EINVAL;
 831         }
 832         return ret;
 833 }
 834
 835 static
 836 int _ltt_context_metadata_statedump(struct ltt_session *session,
 837                                     struct lttng_ctx *ctx)
 838 {
 839         int ret = 0;
 840         int i;
 841
 842         if (!ctx)
 843                 return 0;
 844         for (i = 0; i < ctx->nr_fields; i++) {
 845                 const struct lttng_ctx_field *field = &ctx->fields[i];
 846
 847                 ret = _ltt_field_statedump(session, &field->event_field);
 848                 if (ret)
 849                         return ret;
 850         }
 851         return ret;
 852 }
 853
 854 static
 855 int _ltt_fields_metadata_statedump(struct ltt_session *session,
 856                                    struct ltt_event *event)
 857 {
 858         const struct lttng_event_desc *desc = event->desc;
 859         int ret = 0;
 860         int i;
 861
 862         for (i = 0; i < desc->nr_fields; i++) {
 863                 const struct lttng_event_field *field = &desc->fields[i];
 864
 865                 ret = _ltt_field_statedump(session, field);
 866                 if (ret)
 867                         return ret;
 868         }
 869         return ret;
 870 }
 871
 872 static
 873 int _ltt_event_metadata_statedump(struct ltt_session *session,
 874                                   struct ltt_channel *chan,
 875                                   struct ltt_event *event)
 876 {
 877         int ret = 0;
 878
 879         if (event->metadata_dumped || !CMM_ACCESS_ONCE(session->active))
 880                 return 0;
 881         if (chan == session->metadata)
 882                 return 0;
 883         /*
 884          * Don't print events for which probe load is pending.
 885          */
 886         if (!event->desc)
 887                 return 0;
 888
 889         ret = lttng_metadata_printf(session,
 890                 "event {\n"
 891                 "       name = \"%s\";\n"
 892                 "       id = %u;\n"
 893                 "       stream_id = %u;\n",
 894                 event->desc->name,
 895                 event->id,
 896                 event->chan->id);
 897         if (ret)
 898                 goto end;
 899
 900         if (event->desc->loglevel) {
 901                 ret = lttng_metadata_printf(session,
 902                         "       loglevel = %d;\n",
 903                         *(*event->desc->loglevel));
 904                 if (ret)
 905                         goto end;
 906         }
 907
 908         if (event->ctx) {
 909                 ret = lttng_metadata_printf(session,
 910                         "       context := struct {\n");
 911                 if (ret)
 912                         goto end;
 913         }
 914         ret = _ltt_context_metadata_statedump(session, event->ctx);
 915         if (ret)
 916                 goto end;
 917         if (event->ctx) {
 918                 ret = lttng_metadata_printf(session,
 919                         "       };\n");
 920                 if (ret)
 921                         goto end;
 922         }
 923
 924         ret = lttng_metadata_printf(session,
 925                 "       fields := struct {\n"
 926                 );
 927         if (ret)
 928                 goto end;
 929
 930         ret = _ltt_fields_metadata_statedump(session, event);
 931         if (ret)
 932                 goto end;
 933
 934         /*
 935          * LTTng space reservation can only reserve multiples of the
 936          * byte size.
 937          */
 938         ret = lttng_metadata_printf(session,
 939                 "       };\n"
 940                 "};\n\n");
 941         if (ret)
 942                 goto end;
 943
 944         event->metadata_dumped = 1;
 945 end:
 946         return ret;
 947
 948 }
 949
 950 static
 951 int _ltt_channel_metadata_statedump(struct ltt_session *session,
 952                                     struct ltt_channel *chan)
 953 {
 954         int ret = 0;
 955
 956         if (chan->metadata_dumped || !CMM_ACCESS_ONCE(session->active))
 957                 return 0;
 958         if (chan == session->metadata)
 959                 return 0;
 960
 961         WARN_ON_ONCE(!chan->header_type);
 962         ret = lttng_metadata_printf(session,
 963                 "stream {\n"
 964                 "       id = %u;\n"
 965                 "       event.header := %s;\n"
 966                 "       packet.context := struct packet_context;\n",
 967                 chan->id,
 968                 chan->header_type == 1 ? "struct event_header_compact" :
 969                         "struct event_header_large");
 970         if (ret)
 971                 goto end;
 972
 973         if (chan->ctx) {
 974                 ret = lttng_metadata_printf(session,
 975                         "       event.context := struct {\n");
 976                 if (ret)
 977                         goto end;
 978         }
 979         ret = _ltt_context_metadata_statedump(session, chan->ctx);
 980         if (ret)
 981                 goto end;
 982         if (chan->ctx) {
 983                 ret = lttng_metadata_printf(session,
 984                         "       };\n");
 985                 if (ret)
 986                         goto end;
 987         }
 988
 989         ret = lttng_metadata_printf(session,
 990                 "};\n\n");
 991
 992         chan->metadata_dumped = 1;
 993 end:
 994         return ret;
 995 }
 996
 997 static
 998 int _ltt_stream_packet_context_declare(struct ltt_session *session)
 999 {
1000         return lttng_metadata_printf(session,
1001                 "struct packet_context {\n"
1002                 "       uint64_clock_monotonic_t timestamp_begin;\n"
1003                 "       uint64_clock_monotonic_t timestamp_end;\n"
1004                 "       uint32_t events_discarded;\n"
1005                 "       uint32_t content_size;\n"
1006                 "       uint32_t packet_size;\n"
1007                 "       uint32_t cpu_id;\n"
1008                 "};\n\n"
1009                 );
1010 }
1011
1012 /*
1013  * Compact header:
1014  * id: range: 0 - 30.
1015  * id 31 is reserved to indicate an extended header.
1016  *
1017  * Large header:
1018  * id: range: 0 - 65534.
1019  * id 65535 is reserved to indicate an extended header.
1020  */
1021 static
1022 int _ltt_event_header_declare(struct ltt_session *session)
1023 {
1024         return lttng_metadata_printf(session,
1025         "struct event_header_compact {\n"
1026         "       enum : uint5_t { compact = 0 ... 30, extended = 31 } id;\n"
1027         "       variant <id> {\n"
1028         "               struct {\n"
1029         "                       uint27_clock_monotonic_t timestamp;\n"
1030         "               } compact;\n"
1031         "               struct {\n"
1032         "                       uint32_t id;\n"
1033         "                       uint64_clock_monotonic_t timestamp;\n"
1034         "               } extended;\n"
1035         "       } v;\n"
1036         "} align(%u);\n"
1037         "\n"
1038         "struct event_header_large {\n"
1039         "       enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;\n"
1040         "       variant <id> {\n"
1041         "               struct {\n"
1042         "                       uint32_clock_monotonic_t timestamp;\n"
1043         "               } compact;\n"
1044         "               struct {\n"
1045         "                       uint32_t id;\n"
1046         "                       uint64_clock_monotonic_t timestamp;\n"
1047         "               } extended;\n"
1048         "       } v;\n"
1049         "} align(%u);\n\n",
1050         lttng_alignof(uint32_t) * CHAR_BIT,
1051         lttng_alignof(uint16_t) * CHAR_BIT
1052         );
1053 }
1054
1055 /*
1056  * Approximation of NTP time of day to clock monotonic correlation,
1057  * taken at start of trace.
1058  * Yes, this is only an approximation. Yes, we can (and will) do better
1059  * in future versions.
1060  */
1061 static
1062 uint64_t measure_clock_offset(void)
1063 {
1064         uint64_t offset, monotonic[2], realtime;
1065         struct timespec rts = { 0, 0 };
1066         int ret;
1067
1068         monotonic[0] = trace_clock_read64();
1069         ret = clock_gettime(CLOCK_REALTIME, &rts);
1070         if (ret < 0)
1071                 return 0;
1072         monotonic[1] = trace_clock_read64();
1073         offset = (monotonic[0] + monotonic[1]) >> 1;
1074         realtime = rts.tv_sec * 1000000000ULL;
1075         realtime += rts.tv_nsec;
1076         offset = realtime - offset;
1077         return offset;
1078 }
1079
1080 /*
1081  * Output metadata into this session's metadata buffers.
1082  */
1083 static
1084 int _ltt_session_metadata_statedump(struct ltt_session *session)
1085 {
1086         unsigned char *uuid_c = session->uuid;
1087         char uuid_s[37], clock_uuid_s[CLOCK_UUID_LEN];
1088         struct ltt_channel *chan;
1089         struct ltt_event *event;
1090         int ret = 0;
1091
1092         if (!CMM_ACCESS_ONCE(session->active))
1093                 return 0;
1094         if (session->metadata_dumped)
1095                 goto skip_session;
1096         if (!session->metadata) {
1097                 DBG("LTTng: attempt to start tracing, but metadata channel is not found. Operation abort.\n");
1098                 return -EPERM;
1099         }
1100
1101         snprintf(uuid_s, sizeof(uuid_s),
1102                 "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
1103                 uuid_c[0], uuid_c[1], uuid_c[2], uuid_c[3],
1104                 uuid_c[4], uuid_c[5], uuid_c[6], uuid_c[7],
1105                 uuid_c[8], uuid_c[9], uuid_c[10], uuid_c[11],
1106                 uuid_c[12], uuid_c[13], uuid_c[14], uuid_c[15]);
1107
1108         ret = lttng_metadata_printf(session,
1109                 "typealias integer { size = 8; align = %u; signed = false; } := uint8_t;\n"
1110                 "typealias integer { size = 16; align = %u; signed = false; } := uint16_t;\n"
1111                 "typealias integer { size = 32; align = %u; signed = false; } := uint32_t;\n"
1112                 "typealias integer { size = 64; align = %u; signed = false; } := uint64_t;\n"
1113                 "typealias integer { size = 5; align = 1; signed = false; } := uint5_t;\n"
1114                 "typealias integer { size = 27; align = 1; signed = false; } := uint27_t;\n"
1115                 "\n"
1116                 "trace {\n"
1117                 "       major = %u;\n"
1118                 "       minor = %u;\n"
1119                 "       uuid = \"%s\";\n"
1120                 "       byte_order = %s;\n"
1121                 "       packet.header := struct {\n"
1122                 "               uint32_t magic;\n"
1123                 "               uint8_t  uuid[16];\n"
1124                 "               uint32_t stream_id;\n"
1125                 "       };\n"
1126                 "};\n\n",
1127                 lttng_alignof(uint8_t) * CHAR_BIT,
1128                 lttng_alignof(uint16_t) * CHAR_BIT,
1129                 lttng_alignof(uint32_t) * CHAR_BIT,
1130                 lttng_alignof(uint64_t) * CHAR_BIT,
1131                 CTF_VERSION_MAJOR,
1132                 CTF_VERSION_MINOR,
1133                 uuid_s,
1134 #if (BYTE_ORDER == BIG_ENDIAN)
1135                 "be"
1136 #else
1137                 "le"
1138 #endif
1139                 );
1140         if (ret)
1141                 goto end;
1142
1143         ret = lttng_metadata_printf(session,
1144                 "clock {\n"
1145                 "       name = %s;\n",
1146                 "monotonic"
1147                 );
1148         if (ret)
1149                 goto end;
1150
1151         if (!trace_clock_uuid(clock_uuid_s)) {
1152                 ret = lttng_metadata_printf(session,
1153                         "       uuid = \"%s\";\n",
1154                         clock_uuid_s
1155                         );
1156                 if (ret)
1157                         goto end;
1158         }
1159
1160         ret = lttng_metadata_printf(session,
1161                 "       description = \"Monotonic Clock\";\n"
1162                 "       freq = %" PRIu64 "; /* Frequency, in Hz */\n"
1163                 "       /* clock value offset from Epoch is: offset * (1/freq) */\n"
1164                 "       offset = %" PRIu64 ";\n"
1165                 "};\n\n",
1166                 trace_clock_freq(),
1167                 measure_clock_offset()
1168                 );
1169         if (ret)
1170                 goto end;
1171
1172         ret = lttng_metadata_printf(session,
1173                 "typealias integer {\n"
1174                 "       size = 27; align = 1; signed = false;\n"
1175                 "       map = clock.monotonic.value;\n"
1176                 "} := uint27_clock_monotonic_t;\n"
1177                 "\n"
1178                 "typealias integer {\n"
1179                 "       size = 32; align = %u; signed = false;\n"
1180                 "       map = clock.monotonic.value;\n"
1181                 "} := uint32_clock_monotonic_t;\n"
1182                 "\n"
1183                 "typealias integer {\n"
1184                 "       size = 64; align = %u; signed = false;\n"
1185                 "       map = clock.monotonic.value;\n"
1186                 "} := uint64_clock_monotonic_t;\n\n",
1187                 lttng_alignof(uint32_t) * CHAR_BIT,
1188                 lttng_alignof(uint64_t) * CHAR_BIT
1189                 );
1190         if (ret)
1191                 goto end;
1192
1193         ret = _ltt_stream_packet_context_declare(session);
1194         if (ret)
1195                 goto end;
1196
1197         ret = _ltt_event_header_declare(session);
1198         if (ret)
1199                 goto end;
1200
1201 skip_session:
1202         cds_list_for_each_entry(chan, &session->chan, list) {
1203                 ret = _ltt_channel_metadata_statedump(session, chan);
1204                 if (ret)
1205                         goto end;
1206         }
1207
1208         cds_list_for_each_entry(event, &session->events, list) {
1209                 ret = _ltt_event_metadata_statedump(session, event->chan, event);
1210                 if (ret)
1211                         goto end;
1212         }
1213         session->metadata_dumped = 1;
1214 end:
1215         return ret;
1216 }
1217
1218 void lttng_ust_events_exit(void)
1219 {
1220         struct ltt_session *session, *tmpsession;
1221
1222         cds_list_for_each_entry_safe(session, tmpsession, &sessions, list)
1223                 ltt_session_destroy(session);
1224 }
1225
1226 /* WILDCARDS */
1227
1228 static
1229 int wildcard_same_loglevel(struct wildcard_entry *e,
1230         enum lttng_ust_loglevel_type loglevel_type,
1231         int loglevel)
1232 {
1233         if (e->loglevel_type == loglevel_type && e->loglevel == loglevel)
1234                 return 1;
1235         else
1236                 return 0;
1237 }
1238
1239 #if 0
1240 static
1241 int wildcard_is_within(struct wildcard_entry *e,
1242         enum lttng_ust_loglevel_type loglevel_type,
1243         int loglevel)
1244 {
1245         if (e->loglevel_type == LTTNG_UST_LOGLEVEL_ALL
1246                         || e->loglevel == -1)
1247                 return 1;
1248         switch (e->loglevel_type) {
1249         case LTTNG_UST_LOGLEVEL_RANGE:
1250                 switch (loglevel_type) {
1251                 case LTTNG_UST_LOGLEVEL_RANGE:
1252                         if (e->loglevel >= loglevel)
1253                                 return 1;
1254                         else
1255                                 return 0;
1256                 case LTTNG_UST_LOGLEVEL_SINGLE:
1257                         if (e->loglevel <= 0 && loglevel == 0)
1258                                 return 1;
1259                         else
1260                                 return 0;
1261                 }
1262         case LTTNG_UST_LOGLEVEL_SINGLE:
1263                 switch (loglevel_type) {
1264                 case LTTNG_UST_LOGLEVEL_RANGE:
1265                         if (loglevel <= 0)
1266                                 return 1;
1267                         else
1268                                 return 0;
1269                 case LTTNG_UST_LOGLEVEL_SINGLE:
1270                         if (e->loglevel == loglevel)
1271                                 return 1;
1272                         else
1273                                 return 0;
1274                 }
1275         }
1276 }
1277 #endif
1278
1279 /*
1280  * Add the wildcard to the wildcard list. Must be called with
1281  * ust lock held.
1282  */
1283 static
1284 struct session_wildcard *add_wildcard(struct ltt_channel *chan,
1285         struct lttng_ust_event *event_param)
1286 {
1287         struct wildcard_entry *e;
1288         struct session_wildcard *sw;
1289         size_t name_len = strlen(event_param->name) + 1;
1290         int found = 0;
1291
1292         /*
1293          * Try to find global wildcard entry. Given that this is shared
1294          * across all sessions, we need to check for exact loglevel
1295          * match, not just whether contained within the existing ones.
1296          */
1297         cds_list_for_each_entry(e, &wildcard_list, list) {
1298                 if (!strncmp(event_param->name, e->name,
1299                                 LTTNG_UST_SYM_NAME_LEN - 1)) {
1300                         if (wildcard_same_loglevel(e,
1301                                         event_param->loglevel_type,
1302                                         event_param->loglevel)) {
1303                                 found = 1;
1304                                 break;
1305                         }
1306                 }
1307         }
1308
1309         if (!found) {
1310                 /*
1311                  * Create global wildcard entry if not found. Using
1312                  * zmalloc here to allocate a variable length element.
1313                  * Could cause some memory fragmentation if overused.
1314                  */
1315                 e = zmalloc(sizeof(struct wildcard_entry) + name_len);
1316                 if (!e)
1317                         return ERR_PTR(-ENOMEM);
1318                 memcpy(&e->name[0], event_param->name, name_len);
1319                 cds_list_add(&e->list, &wildcard_list);
1320                 CDS_INIT_LIST_HEAD(&e->session_list);
1321         }
1322
1323         /* session wildcard */
1324         cds_list_for_each_entry(sw, &e->session_list, session_list) {
1325                 if (chan == sw->chan) {
1326                         DBG("wildcard %s busy for this channel",
1327                                 event_param->name);
1328                         return ERR_PTR(-EEXIST);        /* Already there */
1329                 }
1330         }
1331         sw = zmalloc(sizeof(struct session_wildcard));
1332         if (!sw)
1333                 return ERR_PTR(-ENOMEM);
1334         sw->chan = chan;
1335         sw->enabled = 1;
1336         memcpy(&sw->event_param, event_param, sizeof(sw->event_param));
1337         sw->event_param.instrumentation = LTTNG_UST_TRACEPOINT;
1338         sw->event_param.loglevel_type = event_param->loglevel_type;
1339         sw->event_param.loglevel = event_param->loglevel;
1340         CDS_INIT_LIST_HEAD(&sw->events);
1341         cds_list_add(&sw->list, &chan->session->wildcards);
1342         cds_list_add(&sw->session_list, &e->session_list);
1343         sw->entry = e;
1344         ltt_probes_create_wildcard_events(e, sw);
1345         return sw;
1346 }
1347
1348 /*
1349  * Remove the wildcard from the wildcard list. Must be called with
1350  * ust_lock held. Only called at session teardown.
1351  */
1352 static
1353 void _remove_wildcard(struct session_wildcard *wildcard)
1354 {
1355         struct ltt_event *ev, *tmp;
1356
1357         /*
1358          * Just remove the events owned (for enable/disable) by this
1359          * wildcard from the list. The session teardown will take care
1360          * of freeing the event memory.
1361          */
1362         cds_list_for_each_entry_safe(ev, tmp, &wildcard->events,
1363                         wildcard_list) {
1364                 cds_list_del(&ev->wildcard_list);
1365         }
1366         cds_list_del(&wildcard->session_list);
1367         cds_list_del(&wildcard->list);
1368         if (cds_list_empty(&wildcard->entry->session_list)) {
1369                 cds_list_del(&wildcard->entry->list);
1370                 free(wildcard->entry);
1371         }
1372         free(wildcard);
1373 }
1374
1375 int ltt_wildcard_create(struct ltt_channel *chan,
1376         struct lttng_ust_event *event_param,
1377         struct session_wildcard **_sw)
1378 {
1379         struct session_wildcard *sw;
1380
1381         sw = add_wildcard(chan, event_param);
1382         if (!sw || IS_ERR(sw)) {
1383                 return PTR_ERR(sw);
1384         }
1385         *_sw = sw;
1386         return 0;
1387 }
1388
1389 static
1390 void _ltt_wildcard_destroy(struct session_wildcard *sw)
1391 {
1392         _remove_wildcard(sw);
1393 }
1394
1395 int ltt_wildcard_enable(struct session_wildcard *wildcard)
1396 {
1397         struct ltt_event *ev;
1398         int ret;
1399
1400         if (wildcard->enabled)
1401                 return -EEXIST;
1402         cds_list_for_each_entry(ev, &wildcard->events, wildcard_list) {
1403                 ret = ltt_event_enable(ev);
1404                 if (ret) {
1405                         DBG("Error: enable error.\n");
1406                         return ret;
1407                 }
1408         }
1409         wildcard->enabled = 1;
1410         return 0;
1411 }
1412
1413 int ltt_wildcard_disable(struct session_wildcard *wildcard)
1414 {
1415         struct ltt_event *ev;
1416         int ret;
1417
1418         if (!wildcard->enabled)
1419                 return -EEXIST;
1420         cds_list_for_each_entry(ev, &wildcard->events, wildcard_list) {
1421                 ret = ltt_event_disable(ev);
1422                 if (ret) {
1423                         DBG("Error: disable error.\n");
1424                         return ret;
1425                 }
1426         }
1427         wildcard->enabled = 0;
1428         return 0;
1429 }