liblttng-ust/ltt-events.c

   1 /*
   2  * ltt-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 "ltt-tracer.h"
  54 #include "ltt-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 /*
  79  * Wildcard list, containing the active wildcards.
  80  * Protected by ust lock.
  81  */
  82 static CDS_LIST_HEAD(wildcard_list);
  83
  84 /*
  85  * Pending probes hash table, containing the registered ltt events for
  86  * which tracepoint probes are still missing. Protected by the sessions
  87  * mutex.
  88  */
  89 #define PENDING_PROBE_HASH_BITS         6
  90 #define PENDING_PROBE_HASH_SIZE         (1 << PENDING_PROBE_HASH_BITS)
  91 static struct cds_hlist_head pending_probe_table[PENDING_PROBE_HASH_SIZE];
  92
  93 struct ust_pending_probe {
  94         struct ltt_event *event;
  95         struct cds_hlist_node node;
  96         enum lttng_ust_loglevel_type loglevel_type;
  97         int loglevel;
  98         char name[];
  99 };
 100
 101 static void _ltt_event_destroy(struct ltt_event *event);
 102 static void _ltt_wildcard_destroy(struct session_wildcard *sw);
 103 static void _ltt_channel_destroy(struct ltt_channel *chan);
 104 static int _ltt_event_unregister(struct ltt_event *event);
 105 static
 106 int _ltt_event_metadata_statedump(struct ltt_session *session,
 107                                   struct ltt_channel *chan,
 108                                   struct ltt_event *event);
 109 static
 110 int _ltt_session_metadata_statedump(struct ltt_session *session);
 111
 112 int ltt_loglevel_match(const struct lttng_event_desc *desc,
 113                 enum lttng_ust_loglevel_type req_type,
 114                 int req_loglevel)
 115 {
 116         int ev_loglevel;
 117
 118         if (req_type == LTTNG_UST_LOGLEVEL_ALL)
 119                 return 1;
 120         if (!desc->loglevel)
 121                 ev_loglevel = TRACE_DEFAULT;
 122         else
 123                 ev_loglevel = *(*desc->loglevel);
 124         switch (req_type) {
 125         case LTTNG_UST_LOGLEVEL_RANGE:
 126                 if (ev_loglevel <= req_loglevel || req_loglevel == -1)
 127                         return 1;
 128                 else
 129                         return 0;
 130         case LTTNG_UST_LOGLEVEL_SINGLE:
 131                 if (ev_loglevel == req_loglevel || req_loglevel == -1)
 132                         return 1;
 133                 else
 134                         return 0;
 135         case LTTNG_UST_LOGLEVEL_ALL:
 136         default:
 137                 return 1;
 138         }
 139 }
 140
 141 /*
 142  * Return wildcard for a given event name if the event name match the
 143  * one of the wildcards.
 144  * Must be called with ust lock held.
 145  * Returns NULL if not present.
 146  */
 147 static
 148 struct wildcard_entry *match_wildcard(const struct lttng_event_desc *desc)
 149 {
 150         struct wildcard_entry *e;
 151
 152         cds_list_for_each_entry(e, &wildcard_list, list) {
 153                 /* If only contain '*' */
 154                 if (strlen(e->name) == 1)
 155                         goto possible_match;
 156                 /* Compare excluding final '*' */
 157                 if (!strncmp(desc->name, e->name, strlen(e->name) - 1))
 158                         goto possible_match;
 159                 continue;       /* goto next, no match */
 160         possible_match:
 161                 if (ltt_loglevel_match(desc,
 162                                 e->loglevel_type,
 163                                 e->loglevel)) {
 164                         return e;
 165                 }
 166                 /* no match, loop to next */
 167         }
 168         return NULL;
 169 }
 170
 171 /*
 172  * called at event creation if probe is missing.
 173  * called with session mutex held.
 174  */
 175 static
 176 int add_pending_probe(struct ltt_event *event, const char *name,
 177                 enum lttng_ust_loglevel_type loglevel_type,
 178                 int loglevel)
 179 {
 180         struct cds_hlist_head *head;
 181         struct ust_pending_probe *e;
 182         size_t name_len = strlen(name) + 1;
 183         uint32_t hash;
 184
 185         if (name_len > LTTNG_UST_SYM_NAME_LEN) {
 186                 WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_SYM_NAME_LEN);
 187                 name_len = LTTNG_UST_SYM_NAME_LEN;
 188         }
 189         hash = jhash(name, name_len - 1, 0);
 190         head = &pending_probe_table[hash & (PENDING_PROBE_HASH_SIZE - 1)];
 191         e = zmalloc(sizeof(struct ust_pending_probe) + name_len);
 192         if (!e)
 193                 return -ENOMEM;
 194         memcpy(&e->name[0], name, name_len);
 195         e->name[name_len - 1] = '\0';
 196         e->loglevel_type = loglevel_type;
 197         e->loglevel = loglevel;
 198         cds_hlist_add_head(&e->node, head);
 199         e->event = event;
 200         event->pending_probe = e;
 201         return 0;
 202 }
 203
 204 /*
 205  * remove a pending probe. called when at event teardown and when an
 206  * event is fixed (probe is loaded).
 207  * called with session mutex held.
 208  */
 209 static
 210 void remove_pending_probe(struct ust_pending_probe *e)
 211 {
 212         if (!e)
 213                 return;
 214         cds_hlist_del(&e->node);
 215         free(e);
 216 }
 217
 218 /*
 219  * Called at library load: connect the probe on the events pending on
 220  * probe load.
 221  * called with session mutex held.
 222  */
 223 int pending_probe_fix_events(const struct lttng_event_desc *desc)
 224 {
 225         struct cds_hlist_head *head;
 226         struct cds_hlist_node *node, *p;
 227         struct ust_pending_probe *e;
 228         const char *name = desc->name;
 229         int ret = 0;
 230         struct lttng_ust_event event_param;
 231         size_t name_len = strlen(name) + 1;
 232         uint32_t hash;
 233
 234         /* Wildcard */
 235         {
 236                 struct wildcard_entry *wildcard;
 237
 238                 wildcard = match_wildcard(desc);
 239                 if (strcmp(desc->name, "lttng_ust:metadata") && wildcard) {
 240                         struct session_wildcard *sw;
 241
 242                         cds_list_for_each_entry(sw, &wildcard->session_list,
 243                                         session_list) {
 244                                 struct ltt_event *ev;
 245                                 int ret;
 246
 247                                 memcpy(&event_param, &sw->event_param,
 248                                                 sizeof(event_param));
 249                                 memcpy(event_param.name,
 250                                         desc->name,
 251                                         sizeof(event_param.name));
 252                                 /* create event */
 253                                 ret = ltt_event_create(sw->chan,
 254                                         &event_param, &ev);
 255                                 if (ret) {
 256                                         DBG("Error creating event");
 257                                         continue;
 258                                 }
 259                                 cds_list_add(&ev->wildcard_list,
 260                                         &sw->events);
 261                                 lttng_filter_event_link_bytecode(ev,
 262                                         sw->filter_bytecode);
 263                         }
 264                 }
 265         }
 266
 267         if (name_len > LTTNG_UST_SYM_NAME_LEN) {
 268                 WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_SYM_NAME_LEN);
 269                 name_len = LTTNG_UST_SYM_NAME_LEN;
 270         }
 271         hash = jhash(name, name_len - 1, 0);
 272         head = &pending_probe_table[hash & (PENDING_PROBE_HASH_SIZE - 1)];
 273         cds_hlist_for_each_entry_safe(e, node, p, head, node) {
 274                 struct ltt_event *event;
 275                 struct ltt_channel *chan;
 276
 277                 if (!ltt_loglevel_match(desc,
 278                                 e->loglevel_type,
 279                                 e->loglevel)) {
 280                         continue;
 281                 }
 282                 if (strncmp(name, e->name, LTTNG_UST_SYM_NAME_LEN - 1)) {
 283                         continue;
 284                 }
 285                 event = e->event;
 286                 chan = event->chan;
 287                 assert(!event->desc);
 288                 event->desc = desc;
 289                 event->pending_probe = NULL;
 290                 remove_pending_probe(e);
 291                 ret |= __tracepoint_probe_register(name,
 292                                 event->desc->probe_callback,
 293                                 event, event->desc->signature);
 294                 if (ret)
 295                         continue;
 296                 event->id = chan->free_event_id++;
 297                 ret |= _ltt_event_metadata_statedump(chan->session, chan,
 298                                 event);
 299         }
 300         return ret;
 301 }
 302
 303 void synchronize_trace(void)
 304 {
 305         synchronize_rcu();
 306 }
 307
 308 struct ltt_session *ltt_session_create(void)
 309 {
 310         struct ltt_session *session;
 311         int ret;
 312
 313         session = zmalloc(sizeof(struct ltt_session));
 314         if (!session)
 315                 return NULL;
 316         CDS_INIT_LIST_HEAD(&session->chan);
 317         CDS_INIT_LIST_HEAD(&session->events);
 318         CDS_INIT_LIST_HEAD(&session->wildcards);
 319         ret = lttng_ust_uuid_generate(session->uuid);
 320         if (ret != 0) {
 321                 session->uuid[0] = '\0';
 322         }
 323         cds_list_add(&session->list, &sessions);
 324         return session;
 325 }
 326
 327 void ltt_session_destroy(struct ltt_session *session)
 328 {
 329         struct ltt_channel *chan, *tmpchan;
 330         struct ltt_event *event, *tmpevent;
 331         struct session_wildcard *wildcard, *tmpwildcard;
 332         int ret;
 333
 334         CMM_ACCESS_ONCE(session->active) = 0;
 335         cds_list_for_each_entry(event, &session->events, list) {
 336                 ret = _ltt_event_unregister(event);
 337                 WARN_ON(ret);
 338         }
 339         synchronize_trace();    /* Wait for in-flight events to complete */
 340         cds_list_for_each_entry_safe(wildcard, tmpwildcard, &session->wildcards, list)
 341                 _ltt_wildcard_destroy(wildcard);
 342         cds_list_for_each_entry_safe(event, tmpevent, &session->events, list)
 343                 _ltt_event_destroy(event);
 344         cds_list_for_each_entry_safe(chan, tmpchan, &session->chan, list)
 345                 _ltt_channel_destroy(chan);
 346         cds_list_del(&session->list);
 347         free(session);
 348 }
 349
 350 int ltt_session_enable(struct ltt_session *session)
 351 {
 352         int ret = 0;
 353         struct ltt_channel *chan;
 354
 355         if (session->active) {
 356                 ret = -EBUSY;
 357                 goto end;
 358         }
 359
 360         /*
 361          * Snapshot the number of events per channel to know the type of header
 362          * we need to use.
 363          */
 364         cds_list_for_each_entry(chan, &session->chan, list) {
 365                 if (chan->header_type)
 366                         continue;               /* don't change it if session stop/restart */
 367                 if (chan->free_event_id < 31)
 368                         chan->header_type = 1;  /* compact */
 369                 else
 370                         chan->header_type = 2;  /* large */
 371         }
 372
 373         CMM_ACCESS_ONCE(session->active) = 1;
 374         CMM_ACCESS_ONCE(session->been_active) = 1;
 375         ret = _ltt_session_metadata_statedump(session);
 376         if (ret)
 377                 CMM_ACCESS_ONCE(session->active) = 0;
 378 end:
 379         return ret;
 380 }
 381
 382 int ltt_session_disable(struct ltt_session *session)
 383 {
 384         int ret = 0;
 385
 386         if (!session->active) {
 387                 ret = -EBUSY;
 388                 goto end;
 389         }
 390         CMM_ACCESS_ONCE(session->active) = 0;
 391 end:
 392         return ret;
 393 }
 394
 395 int ltt_channel_enable(struct ltt_channel *channel)
 396 {
 397         int old;
 398
 399         if (channel == channel->session->metadata)
 400                 return -EPERM;
 401         old = uatomic_xchg(&channel->enabled, 1);
 402         if (old)
 403                 return -EEXIST;
 404         return 0;
 405 }
 406
 407 int ltt_channel_disable(struct ltt_channel *channel)
 408 {
 409         int old;
 410
 411         if (channel == channel->session->metadata)
 412                 return -EPERM;
 413         old = uatomic_xchg(&channel->enabled, 0);
 414         if (!old)
 415                 return -EEXIST;
 416         return 0;
 417 }
 418
 419 int ltt_event_enable(struct ltt_event *event)
 420 {
 421         int old;
 422
 423         if (event->chan == event->chan->session->metadata)
 424                 return -EPERM;
 425         old = uatomic_xchg(&event->enabled, 1);
 426         if (old)
 427                 return -EEXIST;
 428         return 0;
 429 }
 430
 431 int ltt_event_disable(struct ltt_event *event)
 432 {
 433         int old;
 434
 435         if (event->chan == event->chan->session->metadata)
 436                 return -EPERM;
 437         old = uatomic_xchg(&event->enabled, 0);
 438         if (!old)
 439                 return -EEXIST;
 440         return 0;
 441 }
 442
 443 struct ltt_channel *ltt_channel_create(struct ltt_session *session,
 444                                        const char *transport_name,
 445                                        void *buf_addr,
 446                                        size_t subbuf_size, size_t num_subbuf,
 447                                        unsigned int switch_timer_interval,
 448                                        unsigned int read_timer_interval,
 449                                        int **shm_fd, int **wait_fd,
 450                                        uint64_t **memory_map_size,
 451                                        struct ltt_channel *chan_priv_init)
 452 {
 453         struct ltt_channel *chan = NULL;
 454         struct ltt_transport *transport;
 455
 456         if (session->been_active)
 457                 goto active;    /* Refuse to add channel to active session */
 458         transport = ltt_transport_find(transport_name);
 459         if (!transport) {
 460                 DBG("LTTng transport %s not found\n",
 461                        transport_name);
 462                 goto notransport;
 463         }
 464         chan_priv_init->id = session->free_chan_id++;
 465         chan_priv_init->session = session;
 466         /*
 467          * Note: the channel creation op already writes into the packet
 468          * headers. Therefore the "chan" information used as input
 469          * should be already accessible.
 470          */
 471         chan = transport->ops.channel_create(transport_name, buf_addr,
 472                         subbuf_size, num_subbuf, switch_timer_interval,
 473                         read_timer_interval, shm_fd, wait_fd,
 474                         memory_map_size, chan_priv_init);
 475         if (!chan)
 476                 goto create_error;
 477         chan->enabled = 1;
 478         chan->ops = &transport->ops;
 479         cds_list_add(&chan->list, &session->chan);
 480         return chan;
 481
 482 create_error:
 483 notransport:
 484 active:
 485         return NULL;
 486 }
 487
 488 /*
 489  * Only used internally at session destruction.
 490  */
 491 static
 492 void _ltt_channel_destroy(struct ltt_channel *chan)
 493 {
 494         cds_list_del(&chan->list);
 495         lttng_destroy_context(chan->ctx);
 496         chan->ops->channel_destroy(chan);
 497 }
 498
 499 /*
 500  * Supports event creation while tracing session is active.
 501  */
 502 int ltt_event_create(struct ltt_channel *chan,
 503                 struct lttng_ust_event *event_param,
 504                 struct ltt_event **_event)
 505 {
 506         const struct lttng_event_desc *desc = NULL;     /* silence gcc */
 507         struct ltt_event *event;
 508         int ret = 0;
 509
 510         if (chan->used_event_id == -1U) {
 511                 ret = -ENOMEM;
 512                 goto full;
 513         }
 514         /*
 515          * This is O(n^2) (for each event, the loop is called at event
 516          * creation). Might require a hash if we have lots of events.
 517          */
 518         cds_list_for_each_entry(event, &chan->session->events, list) {
 519                 if (event->desc && !strncmp(event->desc->name,
 520                                 event_param->name,
 521                                 LTTNG_UST_SYM_NAME_LEN - 1)) {
 522                         ret = -EEXIST;
 523                         goto exist;
 524                 }
 525         }
 526
 527         /*
 528          * Check if loglevel match. Refuse to connect event if not.
 529          */
 530         if (event_param->instrumentation == LTTNG_UST_TRACEPOINT) {
 531                 desc = ltt_event_get(event_param->name);
 532                 if (desc) {
 533                         if (!ltt_loglevel_match(desc,
 534                                         event_param->loglevel_type,
 535                                         event_param->loglevel)) {
 536                                 ret = -EPERM;
 537                                 goto no_loglevel_match;
 538                         }
 539                 }
 540                 /*
 541                  * If descriptor is not there, it will be added to
 542                  * pending probes.
 543                  */
 544         }
 545         event = zmalloc(sizeof(struct ltt_event));
 546         if (!event) {
 547                 ret = -ENOMEM;
 548                 goto cache_error;
 549         }
 550         event->chan = chan;
 551         /*
 552          * used_event_id counts the maximum number of event IDs that can
 553          * register if all probes register.
 554          */
 555         chan->used_event_id++;
 556         event->enabled = 1;
 557         event->instrumentation = event_param->instrumentation;
 558         /* Populate ltt_event structure before tracepoint registration. */
 559         cmm_smp_wmb();
 560         switch (event_param->instrumentation) {
 561         case LTTNG_UST_TRACEPOINT:
 562                 event->desc = desc;
 563                 if (event->desc) {
 564                         ret = __tracepoint_probe_register(event_param->name,
 565                                         event->desc->probe_callback,
 566                                         event, event->desc->signature);
 567                         if (ret)
 568                                 goto register_error;
 569                         event->id = chan->free_event_id++;
 570                 } else {
 571                         /*
 572                          * If the probe is not present, event->desc stays NULL,
 573                          * waiting for the probe to register, and the event->id
 574                          * stays unallocated.
 575                          */
 576                         ret = add_pending_probe(event, event_param->name,
 577                                         event_param->loglevel_type,
 578                                         event_param->loglevel);
 579                         if (ret)
 580                                 goto add_pending_error;
 581                 }
 582                 break;
 583         default:
 584                 WARN_ON_ONCE(1);
 585         }
 586         if (event->desc) {
 587                 ret = _ltt_event_metadata_statedump(chan->session, chan, event);
 588                 if (ret)
 589                         goto statedump_error;
 590         }
 591         cds_list_add(&event->list, &chan->session->events);
 592         *_event = event;
 593         return 0;
 594
 595 statedump_error:
 596         if (event->desc) {
 597                 WARN_ON_ONCE(__tracepoint_probe_unregister(event_param->name,
 598                                         event->desc->probe_callback,
 599                                         event));
 600                 ltt_event_put(event->desc);
 601         }
 602 add_pending_error:
 603 register_error:
 604         free(event);
 605 cache_error:
 606 no_loglevel_match:
 607 exist:
 608 full:
 609         return ret;
 610 }
 611
 612 /*
 613  * Only used internally at session destruction.
 614  */
 615 int _ltt_event_unregister(struct ltt_event *event)
 616 {
 617         int ret = -EINVAL;
 618
 619         switch (event->instrumentation) {
 620         case LTTNG_UST_TRACEPOINT:
 621                 if (event->desc) {
 622                         ret = __tracepoint_probe_unregister(event->desc->name,
 623                                                           event->desc->probe_callback,
 624                                                           event);
 625                         if (ret)
 626                                 return ret;
 627                 } else {
 628                         remove_pending_probe(event->pending_probe);
 629                         ret = 0;
 630                 }
 631                 break;
 632         default:
 633                 WARN_ON_ONCE(1);
 634         }
 635         return ret;
 636 }
 637
 638 /*
 639  * Only used internally at session destruction.
 640  */
 641 static
 642 void _ltt_event_destroy(struct ltt_event *event)
 643 {
 644         switch (event->instrumentation) {
 645         case LTTNG_UST_TRACEPOINT:
 646                 if (event->desc) {
 647                         ltt_event_put(event->desc);
 648                 }
 649                 break;
 650         default:
 651                 WARN_ON_ONCE(1);
 652         }
 653         cds_list_del(&event->list);
 654         lttng_destroy_context(event->ctx);
 655         free(event->filter_bytecode);
 656         free(event->filter_data);
 657         free(event);
 658 }
 659
 660 /*
 661  * We have exclusive access to our metadata buffer (protected by the
 662  * ust_lock), so we can do racy operations such as looking for
 663  * remaining space left in packet and write, since mutual exclusion
 664  * protects us from concurrent writes.
 665  */
 666 int lttng_metadata_printf(struct ltt_session *session,
 667                           const char *fmt, ...)
 668 {
 669         struct lttng_ust_lib_ring_buffer_ctx ctx;
 670         struct ltt_channel *chan = session->metadata;
 671         char *str = NULL;
 672         int ret = 0, waitret;
 673         size_t len, reserve_len, pos;
 674         va_list ap;
 675
 676         WARN_ON_ONCE(!CMM_ACCESS_ONCE(session->active));
 677
 678         va_start(ap, fmt);
 679         ret = vasprintf(&str, fmt, ap);
 680         va_end(ap);
 681         if (ret < 0)
 682                 return -ENOMEM;
 683
 684         len = strlen(str);
 685         pos = 0;
 686
 687         for (pos = 0; pos < len; pos += reserve_len) {
 688                 reserve_len = min_t(size_t,
 689                                 chan->ops->packet_avail_size(chan->chan, chan->handle),
 690                                 len - pos);
 691                 lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL, reserve_len,
 692                                          sizeof(char), -1, chan->handle);
 693                 /*
 694                  * We don't care about metadata buffer's records lost
 695                  * count, because we always retry here. Report error if
 696                  * we need to bail out after timeout or being
 697                  * interrupted.
 698                  */
 699                 waitret = wait_cond_interruptible_timeout(
 700                         ({
 701                                 ret = chan->ops->event_reserve(&ctx, 0);
 702                                 ret != -ENOBUFS || !ret;
 703                         }),
 704                         LTTNG_METADATA_TIMEOUT_MSEC);
 705                 if (waitret == -ETIMEDOUT || waitret == -EINTR || ret) {
 706                         DBG("LTTng: Failure to write metadata to buffers (%s)\n",
 707                                 waitret == -EINTR ? "interrupted" :
 708                                         (ret == -ENOBUFS ? "timeout" : "I/O error"));
 709                         if (waitret == -EINTR)
 710                                 ret = waitret;
 711                         goto end;
 712                 }
 713                 chan->ops->event_write(&ctx, &str[pos], reserve_len);
 714                 chan->ops->event_commit(&ctx);
 715         }
 716 end:
 717         free(str);
 718         return ret;
 719 }
 720
 721 static
 722 int _ltt_field_statedump(struct ltt_session *session,
 723                          const struct lttng_event_field *field)
 724 {
 725         int ret = 0;
 726
 727         switch (field->type.atype) {
 728         case atype_integer:
 729                 ret = lttng_metadata_printf(session,
 730                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s;\n",
 731                         field->type.u.basic.integer.size,
 732                         field->type.u.basic.integer.alignment,
 733                         field->type.u.basic.integer.signedness,
 734                         (field->type.u.basic.integer.encoding == lttng_encode_none)
 735                                 ? "none"
 736                                 : (field->type.u.basic.integer.encoding == lttng_encode_UTF8)
 737                                         ? "UTF8"
 738                                         : "ASCII",
 739                         field->type.u.basic.integer.base,
 740 #if (BYTE_ORDER == BIG_ENDIAN)
 741                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 742 #else
 743                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 744 #endif
 745                         field->name);
 746                 break;
 747         case atype_float:
 748                 ret = lttng_metadata_printf(session,
 749                         "               floating_point { exp_dig = %u; mant_dig = %u; align = %u;%s } _%s;\n",
 750                         field->type.u.basic._float.exp_dig,
 751                         field->type.u.basic._float.mant_dig,
 752                         field->type.u.basic._float.alignment,
 753 #if (BYTE_ORDER == BIG_ENDIAN)
 754                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 755 #else
 756                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 757 #endif
 758                         field->name);
 759                 break;
 760         case atype_enum:
 761                 ret = lttng_metadata_printf(session,
 762                         "               %s %s;\n",
 763                         field->type.u.basic.enumeration.name,
 764                         field->name);
 765                 break;
 766         case atype_array:
 767         {
 768                 const struct lttng_basic_type *elem_type;
 769
 770                 elem_type = &field->type.u.array.elem_type;
 771                 ret = lttng_metadata_printf(session,
 772                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[%u];\n",
 773                         elem_type->u.basic.integer.size,
 774                         elem_type->u.basic.integer.alignment,
 775                         elem_type->u.basic.integer.signedness,
 776                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 777                                 ? "none"
 778                                 : (elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 779                                         ? "UTF8"
 780                                         : "ASCII",
 781                         elem_type->u.basic.integer.base,
 782 #if (BYTE_ORDER == BIG_ENDIAN)
 783                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 784 #else
 785                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 786 #endif
 787                         field->name, field->type.u.array.length);
 788                 break;
 789         }
 790         case atype_sequence:
 791         {
 792                 const struct lttng_basic_type *elem_type;
 793                 const struct lttng_basic_type *length_type;
 794
 795                 elem_type = &field->type.u.sequence.elem_type;
 796                 length_type = &field->type.u.sequence.length_type;
 797                 ret = lttng_metadata_printf(session,
 798                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } __%s_length;\n",
 799                         length_type->u.basic.integer.size,
 800                         (unsigned int) length_type->u.basic.integer.alignment,
 801                         length_type->u.basic.integer.signedness,
 802                         (length_type->u.basic.integer.encoding == lttng_encode_none)
 803                                 ? "none"
 804                                 : ((length_type->u.basic.integer.encoding == lttng_encode_UTF8)
 805                                         ? "UTF8"
 806                                         : "ASCII"),
 807                         length_type->u.basic.integer.base,
 808 #if (BYTE_ORDER == BIG_ENDIAN)
 809                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 810 #else
 811                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 812 #endif
 813                         field->name);
 814                 if (ret)
 815                         return ret;
 816
 817                 ret = lttng_metadata_printf(session,
 818                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[ __%s_length ];\n",
 819                         elem_type->u.basic.integer.size,
 820                         (unsigned int) elem_type->u.basic.integer.alignment,
 821                         elem_type->u.basic.integer.signedness,
 822                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 823                                 ? "none"
 824                                 : ((elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 825                                         ? "UTF8"
 826                                         : "ASCII"),
 827                         elem_type->u.basic.integer.base,
 828 #if (BYTE_ORDER == BIG_ENDIAN)
 829                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 830 #else
 831                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 832 #endif
 833                         field->name,
 834                         field->name);
 835                 break;
 836         }
 837
 838         case atype_string:
 839                 /* Default encoding is UTF8 */
 840                 ret = lttng_metadata_printf(session,
 841                         "               string%s _%s;\n",
 842                         field->type.u.basic.string.encoding == lttng_encode_ASCII ?
 843                                 " { encoding = ASCII; }" : "",
 844                         field->name);
 845                 break;
 846         default:
 847                 WARN_ON_ONCE(1);
 848                 return -EINVAL;
 849         }
 850         return ret;
 851 }
 852
 853 static
 854 int _ltt_context_metadata_statedump(struct ltt_session *session,
 855                                     struct lttng_ctx *ctx)
 856 {
 857         int ret = 0;
 858         int i;
 859
 860         if (!ctx)
 861                 return 0;
 862         for (i = 0; i < ctx->nr_fields; i++) {
 863                 const struct lttng_ctx_field *field = &ctx->fields[i];
 864
 865                 ret = _ltt_field_statedump(session, &field->event_field);
 866                 if (ret)
 867                         return ret;
 868         }
 869         return ret;
 870 }
 871
 872 static
 873 int _ltt_fields_metadata_statedump(struct ltt_session *session,
 874                                    struct ltt_event *event)
 875 {
 876         const struct lttng_event_desc *desc = event->desc;
 877         int ret = 0;
 878         int i;
 879
 880         for (i = 0; i < desc->nr_fields; i++) {
 881                 const struct lttng_event_field *field = &desc->fields[i];
 882
 883                 ret = _ltt_field_statedump(session, field);
 884                 if (ret)
 885                         return ret;
 886         }
 887         return ret;
 888 }
 889
 890 static
 891 int _ltt_event_metadata_statedump(struct ltt_session *session,
 892                                   struct ltt_channel *chan,
 893                                   struct ltt_event *event)
 894 {
 895         int ret = 0;
 896         int loglevel = TRACE_DEFAULT;
 897
 898         if (event->metadata_dumped || !CMM_ACCESS_ONCE(session->active))
 899                 return 0;
 900         if (chan == session->metadata)
 901                 return 0;
 902         /*
 903          * Don't print events for which probe load is pending.
 904          */
 905         if (!event->desc)
 906                 return 0;
 907
 908         ret = lttng_metadata_printf(session,
 909                 "event {\n"
 910                 "       name = \"%s\";\n"
 911                 "       id = %u;\n"
 912                 "       stream_id = %u;\n",
 913                 event->desc->name,
 914                 event->id,
 915                 event->chan->id);
 916         if (ret)
 917                 goto end;
 918
 919         if (event->desc->loglevel)
 920                 loglevel = *(*event->desc->loglevel);
 921
 922         ret = lttng_metadata_printf(session,
 923                 "       loglevel = %d;\n",
 924                 loglevel);
 925         if (ret)
 926                 goto end;
 927
 928         if (event->ctx) {
 929                 ret = lttng_metadata_printf(session,
 930                         "       context := struct {\n");
 931                 if (ret)
 932                         goto end;
 933         }
 934         ret = _ltt_context_metadata_statedump(session, event->ctx);
 935         if (ret)
 936                 goto end;
 937         if (event->ctx) {
 938                 ret = lttng_metadata_printf(session,
 939                         "       };\n");
 940                 if (ret)
 941                         goto end;
 942         }
 943
 944         ret = lttng_metadata_printf(session,
 945                 "       fields := struct {\n"
 946                 );
 947         if (ret)
 948                 goto end;
 949
 950         ret = _ltt_fields_metadata_statedump(session, event);
 951         if (ret)
 952                 goto end;
 953
 954         /*
 955          * LTTng space reservation can only reserve multiples of the
 956          * byte size.
 957          */
 958         ret = lttng_metadata_printf(session,
 959                 "       };\n"
 960                 "};\n\n");
 961         if (ret)
 962                 goto end;
 963
 964         event->metadata_dumped = 1;
 965 end:
 966         return ret;
 967
 968 }
 969
 970 static
 971 int _ltt_channel_metadata_statedump(struct ltt_session *session,
 972                                     struct ltt_channel *chan)
 973 {
 974         int ret = 0;
 975
 976         if (chan->metadata_dumped || !CMM_ACCESS_ONCE(session->active))
 977                 return 0;
 978         if (chan == session->metadata)
 979                 return 0;
 980
 981         WARN_ON_ONCE(!chan->header_type);
 982         ret = lttng_metadata_printf(session,
 983                 "stream {\n"
 984                 "       id = %u;\n"
 985                 "       event.header := %s;\n"
 986                 "       packet.context := struct packet_context;\n",
 987                 chan->id,
 988                 chan->header_type == 1 ? "struct event_header_compact" :
 989                         "struct event_header_large");
 990         if (ret)
 991                 goto end;
 992
 993         if (chan->ctx) {
 994                 ret = lttng_metadata_printf(session,
 995                         "       event.context := struct {\n");
 996                 if (ret)
 997                         goto end;
 998         }
 999         ret = _ltt_context_metadata_statedump(session, chan->ctx);
1000         if (ret)
1001                 goto end;
1002         if (chan->ctx) {
1003                 ret = lttng_metadata_printf(session,
1004                         "       };\n");
1005                 if (ret)
1006                         goto end;
1007         }
1008
1009         ret = lttng_metadata_printf(session,
1010                 "};\n\n");
1011
1012         chan->metadata_dumped = 1;
1013 end:
1014         return ret;
1015 }
1016
1017 static
1018 int _ltt_stream_packet_context_declare(struct ltt_session *session)
1019 {
1020         return lttng_metadata_printf(session,
1021                 "struct packet_context {\n"
1022                 "       uint64_clock_monotonic_t timestamp_begin;\n"
1023                 "       uint64_clock_monotonic_t timestamp_end;\n"
1024                 "       unsigned long events_discarded;\n"
1025                 "       uint32_t content_size;\n"
1026                 "       uint32_t packet_size;\n"
1027                 "       uint32_t cpu_id;\n"
1028                 "};\n\n"
1029                 );
1030 }
1031
1032 /*
1033  * Compact header:
1034  * id: range: 0 - 30.
1035  * id 31 is reserved to indicate an extended header.
1036  *
1037  * Large header:
1038  * id: range: 0 - 65534.
1039  * id 65535 is reserved to indicate an extended header.
1040  */
1041 static
1042 int _ltt_event_header_declare(struct ltt_session *session)
1043 {
1044         return lttng_metadata_printf(session,
1045         "struct event_header_compact {\n"
1046         "       enum : uint5_t { compact = 0 ... 30, extended = 31 } id;\n"
1047         "       variant <id> {\n"
1048         "               struct {\n"
1049         "                       uint27_clock_monotonic_t timestamp;\n"
1050         "               } compact;\n"
1051         "               struct {\n"
1052         "                       uint32_t id;\n"
1053         "                       uint64_clock_monotonic_t timestamp;\n"
1054         "               } extended;\n"
1055         "       } v;\n"
1056         "} align(%u);\n"
1057         "\n"
1058         "struct event_header_large {\n"
1059         "       enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;\n"
1060         "       variant <id> {\n"
1061         "               struct {\n"
1062         "                       uint32_clock_monotonic_t timestamp;\n"
1063         "               } compact;\n"
1064         "               struct {\n"
1065         "                       uint32_t id;\n"
1066         "                       uint64_clock_monotonic_t timestamp;\n"
1067         "               } extended;\n"
1068         "       } v;\n"
1069         "} align(%u);\n\n",
1070         lttng_alignof(uint32_t) * CHAR_BIT,
1071         lttng_alignof(uint16_t) * CHAR_BIT
1072         );
1073 }
1074
1075 /*
1076  * Approximation of NTP time of day to clock monotonic correlation,
1077  * taken at start of trace.
1078  * Yes, this is only an approximation. Yes, we can (and will) do better
1079  * in future versions.
1080  */
1081 static
1082 uint64_t measure_clock_offset(void)
1083 {
1084         uint64_t offset, monotonic[2], realtime;
1085         struct timespec rts = { 0, 0 };
1086         int ret;
1087
1088         monotonic[0] = trace_clock_read64();
1089         ret = clock_gettime(CLOCK_REALTIME, &rts);
1090         if (ret < 0)
1091                 return 0;
1092         monotonic[1] = trace_clock_read64();
1093         offset = (monotonic[0] + monotonic[1]) >> 1;
1094         realtime = (uint64_t) rts.tv_sec * 1000000000ULL;
1095         realtime += rts.tv_nsec;
1096         offset = realtime - offset;
1097         return offset;
1098 }
1099
1100 /*
1101  * Output metadata into this session's metadata buffers.
1102  */
1103 static
1104 int _ltt_session_metadata_statedump(struct ltt_session *session)
1105 {
1106         unsigned char *uuid_c = session->uuid;
1107         char uuid_s[LTTNG_UST_UUID_STR_LEN],
1108                 clock_uuid_s[LTTNG_UST_UUID_STR_LEN];
1109         struct ltt_channel *chan;
1110         struct ltt_event *event;
1111         int ret = 0;
1112         char procname[LTTNG_UST_PROCNAME_LEN] = "";
1113
1114         if (!CMM_ACCESS_ONCE(session->active))
1115                 return 0;
1116         if (session->metadata_dumped)
1117                 goto skip_session;
1118         if (!session->metadata) {
1119                 DBG("LTTng: attempt to start tracing, but metadata channel is not found. Operation abort.\n");
1120                 return -EPERM;
1121         }
1122
1123         snprintf(uuid_s, sizeof(uuid_s),
1124                 "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
1125                 uuid_c[0], uuid_c[1], uuid_c[2], uuid_c[3],
1126                 uuid_c[4], uuid_c[5], uuid_c[6], uuid_c[7],
1127                 uuid_c[8], uuid_c[9], uuid_c[10], uuid_c[11],
1128                 uuid_c[12], uuid_c[13], uuid_c[14], uuid_c[15]);
1129
1130         ret = lttng_metadata_printf(session,
1131                 "typealias integer { size = 8; align = %u; signed = false; } := uint8_t;\n"
1132                 "typealias integer { size = 16; align = %u; signed = false; } := uint16_t;\n"
1133                 "typealias integer { size = 32; align = %u; signed = false; } := uint32_t;\n"
1134                 "typealias integer { size = 64; align = %u; signed = false; } := uint64_t;\n"
1135                 "typealias integer { size = %u; align = %u; signed = false; } := unsigned long;\n"
1136                 "typealias integer { size = 5; align = 1; signed = false; } := uint5_t;\n"
1137                 "typealias integer { size = 27; align = 1; signed = false; } := uint27_t;\n"
1138                 "\n"
1139                 "trace {\n"
1140                 "       major = %u;\n"
1141                 "       minor = %u;\n"
1142                 "       uuid = \"%s\";\n"
1143                 "       byte_order = %s;\n"
1144                 "       packet.header := struct {\n"
1145                 "               uint32_t magic;\n"
1146                 "               uint8_t  uuid[16];\n"
1147                 "               uint32_t stream_id;\n"
1148                 "       };\n"
1149                 "};\n\n",
1150                 lttng_alignof(uint8_t) * CHAR_BIT,
1151                 lttng_alignof(uint16_t) * CHAR_BIT,
1152                 lttng_alignof(uint32_t) * CHAR_BIT,
1153                 lttng_alignof(uint64_t) * CHAR_BIT,
1154                 sizeof(unsigned long) * CHAR_BIT,
1155                 lttng_alignof(unsigned long) * CHAR_BIT,
1156                 CTF_SPEC_MAJOR,
1157                 CTF_SPEC_MINOR,
1158                 uuid_s,
1159 #if (BYTE_ORDER == BIG_ENDIAN)
1160                 "be"
1161 #else
1162                 "le"
1163 #endif
1164                 );
1165         if (ret)
1166                 goto end;
1167
1168         /* ignore error, just use empty string if error. */
1169         lttng_ust_getprocname(procname);
1170         procname[LTTNG_UST_PROCNAME_LEN - 1] = '\0';
1171         ret = lttng_metadata_printf(session,
1172                 "env {\n"
1173                 "       vpid = %d;\n"
1174                 "       procname = \"%s\";\n"
1175                 "       domain = \"ust\";\n"
1176                 "       tracer_name = \"lttng-ust\";\n"
1177                 "       tracer_major = %u;\n"
1178                 "       tracer_minor = %u;\n"
1179                 "       tracer_patchlevel = %u;\n"
1180                 "};\n\n",
1181                 (int) getpid(),
1182                 procname,
1183                 LTTNG_UST_MAJOR_VERSION,
1184                 LTTNG_UST_MINOR_VERSION,
1185                 LTTNG_UST_PATCHLEVEL_VERSION
1186                 );
1187         if (ret)
1188                 goto end;
1189
1190         ret = lttng_metadata_printf(session,
1191                 "clock {\n"
1192                 "       name = %s;\n",
1193                 "monotonic"
1194                 );
1195         if (ret)
1196                 goto end;
1197
1198         if (!trace_clock_uuid(clock_uuid_s)) {
1199                 ret = lttng_metadata_printf(session,
1200                         "       uuid = \"%s\";\n",
1201                         clock_uuid_s
1202                         );
1203                 if (ret)
1204                         goto end;
1205         }
1206
1207         ret = lttng_metadata_printf(session,
1208                 "       description = \"Monotonic Clock\";\n"
1209                 "       freq = %" PRIu64 "; /* Frequency, in Hz */\n"
1210                 "       /* clock value offset from Epoch is: offset * (1/freq) */\n"
1211                 "       offset = %" PRIu64 ";\n"
1212                 "};\n\n",
1213                 trace_clock_freq(),
1214                 measure_clock_offset()
1215                 );
1216         if (ret)
1217                 goto end;
1218
1219         ret = lttng_metadata_printf(session,
1220                 "typealias integer {\n"
1221                 "       size = 27; align = 1; signed = false;\n"
1222                 "       map = clock.monotonic.value;\n"
1223                 "} := uint27_clock_monotonic_t;\n"
1224                 "\n"
1225                 "typealias integer {\n"
1226                 "       size = 32; align = %u; signed = false;\n"
1227                 "       map = clock.monotonic.value;\n"
1228                 "} := uint32_clock_monotonic_t;\n"
1229                 "\n"
1230                 "typealias integer {\n"
1231                 "       size = 64; align = %u; signed = false;\n"
1232                 "       map = clock.monotonic.value;\n"
1233                 "} := uint64_clock_monotonic_t;\n\n",
1234                 lttng_alignof(uint32_t) * CHAR_BIT,
1235                 lttng_alignof(uint64_t) * CHAR_BIT
1236                 );
1237         if (ret)
1238                 goto end;
1239
1240         ret = _ltt_stream_packet_context_declare(session);
1241         if (ret)
1242                 goto end;
1243
1244         ret = _ltt_event_header_declare(session);
1245         if (ret)
1246                 goto end;
1247
1248 skip_session:
1249         cds_list_for_each_entry(chan, &session->chan, list) {
1250                 ret = _ltt_channel_metadata_statedump(session, chan);
1251                 if (ret)
1252                         goto end;
1253         }
1254
1255         cds_list_for_each_entry(event, &session->events, list) {
1256                 ret = _ltt_event_metadata_statedump(session, event->chan, event);
1257                 if (ret)
1258                         goto end;
1259         }
1260         session->metadata_dumped = 1;
1261 end:
1262         return ret;
1263 }
1264
1265 void lttng_ust_events_exit(void)
1266 {
1267         struct ltt_session *session, *tmpsession;
1268
1269         cds_list_for_each_entry_safe(session, tmpsession, &sessions, list)
1270                 ltt_session_destroy(session);
1271 }
1272
1273 /* WILDCARDS */
1274
1275 static
1276 int wildcard_same_loglevel(struct wildcard_entry *e,
1277         enum lttng_ust_loglevel_type loglevel_type,
1278         int loglevel)
1279 {
1280         if (e->loglevel_type == loglevel_type && e->loglevel == loglevel)
1281                 return 1;
1282         else
1283                 return 0;
1284 }
1285
1286 #if 0
1287 static
1288 int wildcard_is_within(struct wildcard_entry *e,
1289         enum lttng_ust_loglevel_type loglevel_type,
1290         int loglevel)
1291 {
1292         if (e->loglevel_type == LTTNG_UST_LOGLEVEL_ALL
1293                         || e->loglevel == -1)
1294                 return 1;
1295         switch (e->loglevel_type) {
1296         case LTTNG_UST_LOGLEVEL_RANGE:
1297                 switch (loglevel_type) {
1298                 case LTTNG_UST_LOGLEVEL_RANGE:
1299                         if (e->loglevel >= loglevel)
1300                                 return 1;
1301                         else
1302                                 return 0;
1303                 case LTTNG_UST_LOGLEVEL_SINGLE:
1304                         if (e->loglevel <= 0 && loglevel == 0)
1305                                 return 1;
1306                         else
1307                                 return 0;
1308                 }
1309         case LTTNG_UST_LOGLEVEL_SINGLE:
1310                 switch (loglevel_type) {
1311                 case LTTNG_UST_LOGLEVEL_RANGE:
1312                         if (loglevel <= 0)
1313                                 return 1;
1314                         else
1315                                 return 0;
1316                 case LTTNG_UST_LOGLEVEL_SINGLE:
1317                         if (e->loglevel == loglevel)
1318                                 return 1;
1319                         else
1320                                 return 0;
1321                 }
1322         }
1323 }
1324 #endif
1325
1326 /*
1327  * Add the wildcard to the wildcard list. Must be called with
1328  * ust lock held.
1329  */
1330 static
1331 struct session_wildcard *add_wildcard(struct ltt_channel *chan,
1332         struct lttng_ust_event *event_param)
1333 {
1334         struct wildcard_entry *e;
1335         struct session_wildcard *sw;
1336         size_t name_len = strlen(event_param->name) + 1;
1337         int found = 0;
1338
1339         /*
1340          * Try to find global wildcard entry. Given that this is shared
1341          * across all sessions, we need to check for exact loglevel
1342          * match, not just whether contained within the existing ones.
1343          */
1344         cds_list_for_each_entry(e, &wildcard_list, list) {
1345                 if (!strncmp(event_param->name, e->name,
1346                                 LTTNG_UST_SYM_NAME_LEN - 1)) {
1347                         if (wildcard_same_loglevel(e,
1348                                         event_param->loglevel_type,
1349                                         event_param->loglevel)) {
1350                                 found = 1;
1351                                 break;
1352                         }
1353                 }
1354         }
1355
1356         if (!found) {
1357                 /*
1358                  * Create global wildcard entry if not found. Using
1359                  * zmalloc here to allocate a variable length element.
1360                  * Could cause some memory fragmentation if overused.
1361                  */
1362                 e = zmalloc(sizeof(struct wildcard_entry) + name_len);
1363                 if (!e)
1364                         return ERR_PTR(-ENOMEM);
1365                 memcpy(&e->name[0], event_param->name, name_len);
1366                 e->loglevel_type = event_param->loglevel_type;
1367                 e->loglevel = event_param->loglevel;
1368                 cds_list_add(&e->list, &wildcard_list);
1369                 CDS_INIT_LIST_HEAD(&e->session_list);
1370         }
1371
1372         /* session wildcard */
1373         cds_list_for_each_entry(sw, &e->session_list, session_list) {
1374                 if (chan == sw->chan) {
1375                         DBG("wildcard %s busy for this channel",
1376                                 event_param->name);
1377                         return ERR_PTR(-EEXIST);        /* Already there */
1378                 }
1379         }
1380         sw = zmalloc(sizeof(struct session_wildcard));
1381         if (!sw)
1382                 return ERR_PTR(-ENOMEM);
1383         sw->chan = chan;
1384         sw->enabled = 1;
1385         memcpy(&sw->event_param, event_param, sizeof(sw->event_param));
1386         sw->event_param.instrumentation = LTTNG_UST_TRACEPOINT;
1387         sw->event_param.loglevel_type = event_param->loglevel_type;
1388         sw->event_param.loglevel = event_param->loglevel;
1389         CDS_INIT_LIST_HEAD(&sw->events);
1390         cds_list_add(&sw->list, &chan->session->wildcards);
1391         cds_list_add(&sw->session_list, &e->session_list);
1392         sw->entry = e;
1393         ltt_probes_create_wildcard_events(e, sw);
1394         return sw;
1395 }
1396
1397 /*
1398  * Remove the wildcard from the wildcard list. Must be called with
1399  * ust_lock held. Only called at session teardown.
1400  */
1401 static
1402 void _remove_wildcard(struct session_wildcard *wildcard)
1403 {
1404         struct ltt_event *ev, *tmp;
1405
1406         /*
1407          * Just remove the events owned (for enable/disable) by this
1408          * wildcard from the list. The session teardown will take care
1409          * of freeing the event memory.
1410          */
1411         cds_list_for_each_entry_safe(ev, tmp, &wildcard->events,
1412                         wildcard_list) {
1413                 cds_list_del(&ev->wildcard_list);
1414         }
1415         cds_list_del(&wildcard->session_list);
1416         cds_list_del(&wildcard->list);
1417         if (cds_list_empty(&wildcard->entry->session_list)) {
1418                 cds_list_del(&wildcard->entry->list);
1419                 free(wildcard->entry);
1420         }
1421         free(wildcard->filter_bytecode);
1422         free(wildcard);
1423 }
1424
1425 int ltt_wildcard_create(struct ltt_channel *chan,
1426         struct lttng_ust_event *event_param,
1427         struct session_wildcard **_sw)
1428 {
1429         struct session_wildcard *sw;
1430
1431         sw = add_wildcard(chan, event_param);
1432         if (!sw || IS_ERR(sw)) {
1433                 return PTR_ERR(sw);
1434         }
1435         *_sw = sw;
1436         return 0;
1437 }
1438
1439 static
1440 void _ltt_wildcard_destroy(struct session_wildcard *sw)
1441 {
1442         _remove_wildcard(sw);
1443 }
1444
1445 int ltt_wildcard_enable(struct session_wildcard *wildcard)
1446 {
1447         struct ltt_event *ev;
1448         int ret;
1449
1450         if (wildcard->enabled)
1451                 return -EEXIST;
1452         cds_list_for_each_entry(ev, &wildcard->events, wildcard_list) {
1453                 ret = ltt_event_enable(ev);
1454                 if (ret) {
1455                         DBG("Error: enable error.\n");
1456                         return ret;
1457                 }
1458         }
1459         wildcard->enabled = 1;
1460         return 0;
1461 }
1462
1463 int ltt_wildcard_disable(struct session_wildcard *wildcard)
1464 {
1465         struct ltt_event *ev;
1466         int ret;
1467
1468         if (!wildcard->enabled)
1469                 return -EEXIST;
1470         cds_list_for_each_entry(ev, &wildcard->events, wildcard_list) {
1471                 ret = ltt_event_disable(ev);
1472                 if (ret) {
1473                         DBG("Error: disable error.\n");
1474                         return ret;
1475                 }
1476         }
1477         wildcard->enabled = 0;
1478         return 0;
1479 }
1480
1481 /*
1482  * Take the TLS "fault" in libuuid if dlopen'd, which can take the
1483  * dynamic linker mutex, outside of the UST lock, since the UST lock is
1484  * taken in constructors, which are called with dynamic linker mutex
1485  * held.
1486  */
1487 void lttng_fixup_event_tls(void)
1488 {
1489         unsigned char uuid[LTTNG_UST_UUID_STR_LEN];
1490
1491         (void) lttng_ust_uuid_generate(uuid);
1492 }