liblttng-ust/lttng-events.c

   1 /*
   2  * lttng-events.c
   3  *
   4  * Holds LTTng per-session event registry.
   5  *
   6  * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #define _GNU_SOURCE
  24 #include <stdio.h>
  25 #include <urcu/list.h>
  26 #include <urcu/hlist.h>
  27 #include <pthread.h>
  28 #include <errno.h>
  29 #include <sys/shm.h>
  30 #include <sys/ipc.h>
  31 #include <stdint.h>
  32 #include <stddef.h>
  33 #include <inttypes.h>
  34 #include <time.h>
  35 #include <lttng/ust-endian.h>
  36 #include "clock.h"
  37
  38 #include <urcu-bp.h>
  39 #include <urcu/compiler.h>
  40 #include <urcu/uatomic.h>
  41 #include <urcu/arch.h>
  42
  43 #include <lttng/tracepoint.h>
  44 #include <lttng/ust-events.h>
  45
  46 #include <usterr-signal-safe.h>
  47 #include <helper.h>
  48 #include <lttng/ust-ctl.h>
  49 #include <ust-comm.h>
  50 #include <lttng/ust-dynamic-type.h>
  51 #include <lttng/ust-context-provider.h>
  52 #include "error.h"
  53 #include "compat.h"
  54 #include "lttng-ust-uuid.h"
  55
  56 #include "tracepoint-internal.h"
  57 #include "lttng-tracer.h"
  58 #include "lttng-tracer-core.h"
  59 #include "lttng-ust-statedump.h"
  60 #include "wait.h"
  61 #include "../libringbuffer/shm.h"
  62 #include "jhash.h"
  63
  64 /*
  65  * All operations within this file are called by the communication
  66  * thread, under ust_lock protection.
  67  */
  68
  69 static CDS_LIST_HEAD(sessions);
  70
  71 struct cds_list_head *_lttng_get_sessions(void)
  72 {
  73         return &sessions;
  74 }
  75
  76 static void _lttng_event_destroy(struct lttng_event *event);
  77 static void _lttng_enum_destroy(struct lttng_enum *_enum);
  78
  79 static
  80 void lttng_session_lazy_sync_enablers(struct lttng_session *session);
  81 static
  82 void lttng_session_sync_enablers(struct lttng_session *session);
  83 static
  84 void lttng_enabler_destroy(struct lttng_enabler *enabler);
  85
  86 /*
  87  * Called with ust lock held.
  88  */
  89 int lttng_session_active(void)
  90 {
  91         struct lttng_session *iter;
  92
  93         cds_list_for_each_entry(iter, &sessions, node) {
  94                 if (iter->active)
  95                         return 1;
  96         }
  97         return 0;
  98 }
  99
 100 static
 101 int lttng_loglevel_match(int loglevel,
 102                 unsigned int has_loglevel,
 103                 enum lttng_ust_loglevel_type req_type,
 104                 int req_loglevel)
 105 {
 106         if (!has_loglevel)
 107                 loglevel = TRACE_DEFAULT;
 108         switch (req_type) {
 109         case LTTNG_UST_LOGLEVEL_RANGE:
 110                 if (loglevel <= req_loglevel
 111                                 || (req_loglevel == -1 && loglevel <= TRACE_DEBUG))
 112                         return 1;
 113                 else
 114                         return 0;
 115         case LTTNG_UST_LOGLEVEL_SINGLE:
 116                 if (loglevel == req_loglevel
 117                                 || (req_loglevel == -1 && loglevel <= TRACE_DEBUG))
 118                         return 1;
 119                 else
 120                         return 0;
 121         case LTTNG_UST_LOGLEVEL_ALL:
 122         default:
 123                 if (loglevel <= TRACE_DEBUG)
 124                         return 1;
 125                 else
 126                         return 0;
 127         }
 128 }
 129
 130 void synchronize_trace(void)
 131 {
 132         synchronize_rcu();
 133 }
 134
 135 struct lttng_session *lttng_session_create(void)
 136 {
 137         struct lttng_session *session;
 138         int i;
 139
 140         session = zmalloc(sizeof(struct lttng_session));
 141         if (!session)
 142                 return NULL;
 143         if (lttng_session_context_init(&session->ctx)) {
 144                 free(session);
 145                 return NULL;
 146         }
 147         CDS_INIT_LIST_HEAD(&session->chan_head);
 148         CDS_INIT_LIST_HEAD(&session->events_head);
 149         CDS_INIT_LIST_HEAD(&session->enums_head);
 150         CDS_INIT_LIST_HEAD(&session->enablers_head);
 151         for (i = 0; i < LTTNG_UST_EVENT_HT_SIZE; i++)
 152                 CDS_INIT_HLIST_HEAD(&session->events_ht.table[i]);
 153         for (i = 0; i < LTTNG_UST_ENUM_HT_SIZE; i++)
 154                 CDS_INIT_HLIST_HEAD(&session->enums_ht.table[i]);
 155         cds_list_add(&session->node, &sessions);
 156         return session;
 157 }
 158
 159 /*
 160  * Only used internally at session destruction.
 161  */
 162 static
 163 void _lttng_channel_unmap(struct lttng_channel *lttng_chan)
 164 {
 165         struct channel *chan;
 166         struct lttng_ust_shm_handle *handle;
 167
 168         cds_list_del(&lttng_chan->node);
 169         lttng_destroy_context(lttng_chan->ctx);
 170         chan = lttng_chan->chan;
 171         handle = lttng_chan->handle;
 172         /*
 173          * note: lttng_chan is private data contained within handle. It
 174          * will be freed along with the handle.
 175          */
 176         channel_destroy(chan, handle, 0);
 177 }
 178
 179 static
 180 void register_event(struct lttng_event *event)
 181 {
 182         int ret;
 183         const struct lttng_event_desc *desc;
 184
 185         assert(event->registered == 0);
 186         desc = event->desc;
 187         ret = __tracepoint_probe_register(desc->name,
 188                         desc->probe_callback,
 189                         event, desc->signature);
 190         WARN_ON_ONCE(ret);
 191         if (!ret)
 192                 event->registered = 1;
 193 }
 194
 195 static
 196 void unregister_event(struct lttng_event *event)
 197 {
 198         int ret;
 199         const struct lttng_event_desc *desc;
 200
 201         assert(event->registered == 1);
 202         desc = event->desc;
 203         ret = __tracepoint_probe_unregister(desc->name,
 204                         desc->probe_callback,
 205                         event);
 206         WARN_ON_ONCE(ret);
 207         if (!ret)
 208                 event->registered = 0;
 209 }
 210
 211 /*
 212  * Only used internally at session destruction.
 213  */
 214 static
 215 void _lttng_event_unregister(struct lttng_event *event)
 216 {
 217         if (event->registered)
 218                 unregister_event(event);
 219 }
 220
 221 void lttng_session_destroy(struct lttng_session *session)
 222 {
 223         struct lttng_channel *chan, *tmpchan;
 224         struct lttng_event *event, *tmpevent;
 225         struct lttng_enum *_enum, *tmp_enum;
 226         struct lttng_enabler *enabler, *tmpenabler;
 227
 228         CMM_ACCESS_ONCE(session->active) = 0;
 229         cds_list_for_each_entry(event, &session->events_head, node) {
 230                 _lttng_event_unregister(event);
 231         }
 232         synchronize_trace();    /* Wait for in-flight events to complete */
 233         cds_list_for_each_entry_safe(enabler, tmpenabler,
 234                         &session->enablers_head, node)
 235                 lttng_enabler_destroy(enabler);
 236         cds_list_for_each_entry_safe(event, tmpevent,
 237                         &session->events_head, node)
 238                 _lttng_event_destroy(event);
 239         cds_list_for_each_entry_safe(_enum, tmp_enum,
 240                         &session->enums_head, node)
 241                 _lttng_enum_destroy(_enum);
 242         cds_list_for_each_entry_safe(chan, tmpchan, &session->chan_head, node)
 243                 _lttng_channel_unmap(chan);
 244         cds_list_del(&session->node);
 245         lttng_destroy_context(session->ctx);
 246         free(session);
 247 }
 248
 249 static
 250 int lttng_enum_create(const struct lttng_enum_desc *desc,
 251                 struct lttng_session *session)
 252 {
 253         const char *enum_name = desc->name;
 254         struct lttng_enum *_enum;
 255         struct cds_hlist_head *head;
 256         struct cds_hlist_node *node;
 257         int ret = 0;
 258         size_t name_len = strlen(enum_name);
 259         uint32_t hash;
 260         int notify_socket;
 261
 262         hash = jhash(enum_name, name_len, 0);
 263         head = &session->enums_ht.table[hash & (LTTNG_UST_ENUM_HT_SIZE - 1)];
 264         cds_hlist_for_each_entry(_enum, node, head, hlist) {
 265                 assert(_enum->desc);
 266                 if (!strncmp(_enum->desc->name, desc->name,
 267                                 LTTNG_UST_SYM_NAME_LEN - 1)) {
 268                         ret = -EEXIST;
 269                         goto exist;
 270                 }
 271         }
 272
 273         notify_socket = lttng_get_notify_socket(session->owner);
 274         if (notify_socket < 0) {
 275                 ret = notify_socket;
 276                 goto socket_error;
 277         }
 278
 279         _enum = zmalloc(sizeof(*_enum));
 280         if (!_enum) {
 281                 ret = -ENOMEM;
 282                 goto cache_error;
 283         }
 284         _enum->session = session;
 285         _enum->desc = desc;
 286
 287         ret = ustcomm_register_enum(notify_socket,
 288                 session->objd,
 289                 enum_name,
 290                 desc->nr_entries,
 291                 desc->entries,
 292                 &_enum->id);
 293         if (ret < 0) {
 294                 DBG("Error (%d) registering enumeration to sessiond", ret);
 295                 goto sessiond_register_error;
 296         }
 297         cds_list_add(&_enum->node, &session->enums_head);
 298         cds_hlist_add_head(&_enum->hlist, head);
 299         return 0;
 300
 301 sessiond_register_error:
 302         free(_enum);
 303 cache_error:
 304 socket_error:
 305 exist:
 306         return ret;
 307 }
 308
 309 static
 310 int lttng_create_enum_check(const struct lttng_type *type,
 311                 struct lttng_session *session)
 312 {
 313         switch (type->atype) {
 314         case atype_enum:
 315         {
 316                 const struct lttng_enum_desc *enum_desc;
 317                 int ret;
 318
 319                 enum_desc = type->u.basic.enumeration.desc;
 320                 ret = lttng_enum_create(enum_desc, session);
 321                 if (ret && ret != -EEXIST) {
 322                         DBG("Unable to create enum error: (%d)", ret);
 323                         return ret;
 324                 }
 325                 break;
 326         }
 327         case atype_dynamic:
 328         {
 329                 const struct lttng_event_field *tag_field_generic;
 330                 const struct lttng_enum_desc *enum_desc;
 331                 int ret;
 332
 333                 tag_field_generic = lttng_ust_dynamic_type_tag_field();
 334                 enum_desc = tag_field_generic->type.u.basic.enumeration.desc;
 335                 ret = lttng_enum_create(enum_desc, session);
 336                 if (ret && ret != -EEXIST) {
 337                         DBG("Unable to create enum error: (%d)", ret);
 338                         return ret;
 339                 }
 340                 break;
 341         }
 342         default:
 343                 /* TODO: nested types when they become supported. */
 344                 break;
 345         }
 346         return 0;
 347 }
 348
 349 static
 350 int lttng_create_all_event_enums(size_t nr_fields,
 351                 const struct lttng_event_field *event_fields,
 352                 struct lttng_session *session)
 353 {
 354         size_t i;
 355         int ret;
 356
 357         /* For each field, ensure enum is part of the session. */
 358         for (i = 0; i < nr_fields; i++) {
 359                 const struct lttng_type *type = &event_fields[i].type;
 360
 361                 ret = lttng_create_enum_check(type, session);
 362                 if (ret)
 363                         return ret;
 364         }
 365         return 0;
 366 }
 367
 368 static
 369 int lttng_create_all_ctx_enums(size_t nr_fields,
 370                 const struct lttng_ctx_field *ctx_fields,
 371                 struct lttng_session *session)
 372 {
 373         size_t i;
 374         int ret;
 375
 376         /* For each field, ensure enum is part of the session. */
 377         for (i = 0; i < nr_fields; i++) {
 378                 const struct lttng_type *type = &ctx_fields[i].event_field.type;
 379
 380                 ret = lttng_create_enum_check(type, session);
 381                 if (ret)
 382                         return ret;
 383         }
 384         return 0;
 385 }
 386
 387 /*
 388  * Ensure that a state-dump will be performed for this session at the end
 389  * of the current handle_message().
 390  */
 391 int lttng_session_statedump(struct lttng_session *session)
 392 {
 393         session->statedump_pending = 1;
 394         lttng_ust_sockinfo_session_enabled(session->owner);
 395         return 0;
 396 }
 397
 398 int lttng_session_enable(struct lttng_session *session)
 399 {
 400         int ret = 0;
 401         struct lttng_channel *chan;
 402         int notify_socket;
 403
 404         if (session->active) {
 405                 ret = -EBUSY;
 406                 goto end;
 407         }
 408
 409         notify_socket = lttng_get_notify_socket(session->owner);
 410         if (notify_socket < 0)
 411                 return notify_socket;
 412
 413         /* Set transient enabler state to "enabled" */
 414         session->tstate = 1;
 415
 416         /*
 417          * Snapshot the number of events per channel to know the type of header
 418          * we need to use.
 419          */
 420         cds_list_for_each_entry(chan, &session->chan_head, node) {
 421                 const struct lttng_ctx *ctx;
 422                 const struct lttng_ctx_field *fields = NULL;
 423                 size_t nr_fields = 0;
 424                 uint32_t chan_id;
 425
 426                 /* don't change it if session stop/restart */
 427                 if (chan->header_type)
 428                         continue;
 429                 ctx = chan->ctx;
 430                 if (ctx) {
 431                         nr_fields = ctx->nr_fields;
 432                         fields = ctx->fields;
 433                         ret = lttng_create_all_ctx_enums(nr_fields, fields,
 434                                 session);
 435                         if (ret < 0) {
 436                                 DBG("Error (%d) adding enum to session", ret);
 437                                 return ret;
 438                         }
 439                 }
 440                 ret = ustcomm_register_channel(notify_socket,
 441                         session,
 442                         session->objd,
 443                         chan->objd,
 444                         nr_fields,
 445                         fields,
 446                         &chan_id,
 447                         &chan->header_type);
 448                 if (ret) {
 449                         DBG("Error (%d) registering channel to sessiond", ret);
 450                         return ret;
 451                 }
 452                 if (chan_id != chan->id) {
 453                         DBG("Error: channel registration id (%u) does not match id assigned at creation (%u)",
 454                                 chan_id, chan->id);
 455                         return -EINVAL;
 456                 }
 457         }
 458
 459         /* We need to sync enablers with session before activation. */
 460         lttng_session_sync_enablers(session);
 461
 462         /* Set atomically the state to "active" */
 463         CMM_ACCESS_ONCE(session->active) = 1;
 464         CMM_ACCESS_ONCE(session->been_active) = 1;
 465
 466         ret = lttng_session_statedump(session);
 467         if (ret)
 468                 return ret;
 469 end:
 470         return ret;
 471 }
 472
 473 int lttng_session_disable(struct lttng_session *session)
 474 {
 475         int ret = 0;
 476
 477         if (!session->active) {
 478                 ret = -EBUSY;
 479                 goto end;
 480         }
 481         /* Set atomically the state to "inactive" */
 482         CMM_ACCESS_ONCE(session->active) = 0;
 483
 484         /* Set transient enabler state to "disabled" */
 485         session->tstate = 0;
 486         lttng_session_sync_enablers(session);
 487 end:
 488         return ret;
 489 }
 490
 491 int lttng_channel_enable(struct lttng_channel *channel)
 492 {
 493         int ret = 0;
 494
 495         if (channel->enabled) {
 496                 ret = -EBUSY;
 497                 goto end;
 498         }
 499         /* Set transient enabler state to "enabled" */
 500         channel->tstate = 1;
 501         lttng_session_sync_enablers(channel->session);
 502         /* Set atomically the state to "enabled" */
 503         CMM_ACCESS_ONCE(channel->enabled) = 1;
 504 end:
 505         return ret;
 506 }
 507
 508 int lttng_channel_disable(struct lttng_channel *channel)
 509 {
 510         int ret = 0;
 511
 512         if (!channel->enabled) {
 513                 ret = -EBUSY;
 514                 goto end;
 515         }
 516         /* Set atomically the state to "disabled" */
 517         CMM_ACCESS_ONCE(channel->enabled) = 0;
 518         /* Set transient enabler state to "enabled" */
 519         channel->tstate = 0;
 520         lttng_session_sync_enablers(channel->session);
 521 end:
 522         return ret;
 523 }
 524
 525 /*
 526  * Supports event creation while tracing session is active.
 527  */
 528 static
 529 int lttng_event_create(const struct lttng_event_desc *desc,
 530                 struct lttng_channel *chan)
 531 {
 532         const char *event_name = desc->name;
 533         struct lttng_event *event;
 534         struct lttng_session *session = chan->session;
 535         struct cds_hlist_head *head;
 536         struct cds_hlist_node *node;
 537         int ret = 0;
 538         size_t name_len = strlen(event_name);
 539         uint32_t hash;
 540         int notify_socket, loglevel;
 541         const char *uri;
 542
 543         hash = jhash(event_name, name_len, 0);
 544         head = &chan->session->events_ht.table[hash & (LTTNG_UST_EVENT_HT_SIZE - 1)];
 545         cds_hlist_for_each_entry(event, node, head, hlist) {
 546                 assert(event->desc);
 547                 if (!strncmp(event->desc->name, desc->name,
 548                                         LTTNG_UST_SYM_NAME_LEN - 1)
 549                                 && chan == event->chan) {
 550                         ret = -EEXIST;
 551                         goto exist;
 552                 }
 553         }
 554
 555         notify_socket = lttng_get_notify_socket(session->owner);
 556         if (notify_socket < 0) {
 557                 ret = notify_socket;
 558                 goto socket_error;
 559         }
 560
 561         ret = lttng_create_all_event_enums(desc->nr_fields, desc->fields,
 562                         session);
 563         if (ret < 0) {
 564                 DBG("Error (%d) adding enum to session", ret);
 565                 goto create_enum_error;
 566         }
 567
 568         /*
 569          * Check if loglevel match. Refuse to connect event if not.
 570          */
 571         event = zmalloc(sizeof(struct lttng_event));
 572         if (!event) {
 573                 ret = -ENOMEM;
 574                 goto cache_error;
 575         }
 576         event->chan = chan;
 577
 578         /* Event will be enabled by enabler sync. */
 579         event->enabled = 0;
 580         event->registered = 0;
 581         CDS_INIT_LIST_HEAD(&event->bytecode_runtime_head);
 582         CDS_INIT_LIST_HEAD(&event->enablers_ref_head);
 583         event->desc = desc;
 584
 585         if (desc->loglevel)
 586                 loglevel = *(*event->desc->loglevel);
 587         else
 588                 loglevel = TRACE_DEFAULT;
 589         if (desc->u.ext.model_emf_uri)
 590                 uri = *(desc->u.ext.model_emf_uri);
 591         else
 592                 uri = NULL;
 593
 594         /* Fetch event ID from sessiond */
 595         ret = ustcomm_register_event(notify_socket,
 596                 session,
 597                 session->objd,
 598                 chan->objd,
 599                 event_name,
 600                 loglevel,
 601                 desc->signature,
 602                 desc->nr_fields,
 603                 desc->fields,
 604                 uri,
 605                 &event->id);
 606         if (ret < 0) {
 607                 DBG("Error (%d) registering event to sessiond", ret);
 608                 goto sessiond_register_error;
 609         }
 610
 611         /* Populate lttng_event structure before tracepoint registration. */
 612         cmm_smp_wmb();
 613         cds_list_add(&event->node, &chan->session->events_head);
 614         cds_hlist_add_head(&event->hlist, head);
 615         return 0;
 616
 617 sessiond_register_error:
 618         free(event);
 619 cache_error:
 620 create_enum_error:
 621 socket_error:
 622 exist:
 623         return ret;
 624 }
 625
 626 static
 627 int lttng_desc_match_wildcard_enabler(const struct lttng_event_desc *desc,
 628                 struct lttng_enabler *enabler)
 629 {
 630         int loglevel = 0;
 631         unsigned int has_loglevel = 0;
 632
 633         assert(enabler->type == LTTNG_ENABLER_WILDCARD);
 634         /* Compare excluding final '*' */
 635         if (strncmp(desc->name, enabler->event_param.name,
 636                         strlen(enabler->event_param.name) - 1))
 637                 return 0;
 638         if (desc->loglevel) {
 639                 loglevel = *(*desc->loglevel);
 640                 has_loglevel = 1;
 641         }
 642         if (!lttng_loglevel_match(loglevel,
 643                         has_loglevel,
 644                         enabler->event_param.loglevel_type,
 645                         enabler->event_param.loglevel))
 646                 return 0;
 647         return 1;
 648 }
 649
 650 static
 651 int lttng_desc_match_event_enabler(const struct lttng_event_desc *desc,
 652                 struct lttng_enabler *enabler)
 653 {
 654         int loglevel = 0;
 655         unsigned int has_loglevel = 0;
 656
 657         assert(enabler->type == LTTNG_ENABLER_EVENT);
 658         if (strcmp(desc->name, enabler->event_param.name))
 659                 return 0;
 660         if (desc->loglevel) {
 661                 loglevel = *(*desc->loglevel);
 662                 has_loglevel = 1;
 663         }
 664         if (!lttng_loglevel_match(loglevel,
 665                         has_loglevel,
 666                         enabler->event_param.loglevel_type,
 667                         enabler->event_param.loglevel))
 668                 return 0;
 669         return 1;
 670 }
 671
 672 static
 673 int lttng_desc_match_enabler(const struct lttng_event_desc *desc,
 674                 struct lttng_enabler *enabler)
 675 {
 676         struct lttng_ust_excluder_node *excluder;
 677
 678         /* If event matches with an excluder, return 'does not match' */
 679         cds_list_for_each_entry(excluder, &enabler->excluder_head, node) {
 680                 int count;
 681
 682                 for (count = 0; count < excluder->excluder.count; count++) {
 683                         int found, len;
 684                         char *excluder_name;
 685
 686                         excluder_name = (char *) (excluder->excluder.names)
 687                                         + count * LTTNG_UST_SYM_NAME_LEN;
 688                         len = strnlen(excluder_name, LTTNG_UST_SYM_NAME_LEN);
 689                         if (len > 0 && excluder_name[len - 1] == '*') {
 690                                 found = !strncmp(desc->name, excluder_name,
 691                                                 len - 1);
 692                         } else {
 693                                 found = !strncmp(desc->name, excluder_name,
 694                                                 LTTNG_UST_SYM_NAME_LEN - 1);
 695                         }
 696                         if (found) {
 697                                 return 0;
 698                         }
 699                 }
 700         }
 701         switch (enabler->type) {
 702         case LTTNG_ENABLER_WILDCARD:
 703                 return lttng_desc_match_wildcard_enabler(desc, enabler);
 704         case LTTNG_ENABLER_EVENT:
 705                 return lttng_desc_match_event_enabler(desc, enabler);
 706         default:
 707                 return -EINVAL;
 708         }
 709 }
 710
 711 static
 712 int lttng_event_match_enabler(struct lttng_event *event,
 713                 struct lttng_enabler *enabler)
 714 {
 715         if (lttng_desc_match_enabler(event->desc, enabler)
 716                         && event->chan == enabler->chan)
 717                 return 1;
 718         else
 719                 return 0;
 720 }
 721
 722 static
 723 struct lttng_enabler_ref * lttng_event_enabler_ref(struct lttng_event *event,
 724                 struct lttng_enabler *enabler)
 725 {
 726         struct lttng_enabler_ref *enabler_ref;
 727
 728         cds_list_for_each_entry(enabler_ref,
 729                         &event->enablers_ref_head, node) {
 730                 if (enabler_ref->ref == enabler)
 731                         return enabler_ref;
 732         }
 733         return NULL;
 734 }
 735
 736 /*
 737  * Create struct lttng_event if it is missing and present in the list of
 738  * tracepoint probes.
 739  */
 740 static
 741 void lttng_create_event_if_missing(struct lttng_enabler *enabler)
 742 {
 743         struct lttng_session *session = enabler->chan->session;
 744         struct lttng_probe_desc *probe_desc;
 745         const struct lttng_event_desc *desc;
 746         struct lttng_event *event;
 747         int i;
 748         struct cds_list_head *probe_list;
 749
 750         probe_list = lttng_get_probe_list_head();
 751         /*
 752          * For each probe event, if we find that a probe event matches
 753          * our enabler, create an associated lttng_event if not
 754          * already present.
 755          */
 756         cds_list_for_each_entry(probe_desc, probe_list, head) {
 757                 for (i = 0; i < probe_desc->nr_events; i++) {
 758                         int found = 0, ret;
 759                         struct cds_hlist_head *head;
 760                         struct cds_hlist_node *node;
 761                         const char *event_name;
 762                         size_t name_len;
 763                         uint32_t hash;
 764
 765                         desc = probe_desc->event_desc[i];
 766                         if (!lttng_desc_match_enabler(desc, enabler))
 767                                 continue;
 768                         event_name = desc->name;
 769                         name_len = strlen(event_name);
 770
 771                         /*
 772                          * Check if already created.
 773                          */
 774                         hash = jhash(event_name, name_len, 0);
 775                         head = &session->events_ht.table[hash & (LTTNG_UST_EVENT_HT_SIZE - 1)];
 776                         cds_hlist_for_each_entry(event, node, head, hlist) {
 777                                 if (event->desc == desc
 778                                                 && event->chan == enabler->chan)
 779                                         found = 1;
 780                         }
 781                         if (found)
 782                                 continue;
 783
 784                         /*
 785                          * We need to create an event for this
 786                          * event probe.
 787                          */
 788                         ret = lttng_event_create(probe_desc->event_desc[i],
 789                                         enabler->chan);
 790                         if (ret) {
 791                                 DBG("Unable to create event %s, error %d\n",
 792                                         probe_desc->event_desc[i]->name, ret);
 793                         }
 794                 }
 795         }
 796 }
 797
 798 /*
 799  * Create events associated with an enabler (if not already present),
 800  * and add backward reference from the event to the enabler.
 801  */
 802 static
 803 int lttng_enabler_ref_events(struct lttng_enabler *enabler)
 804 {
 805         struct lttng_session *session = enabler->chan->session;
 806         struct lttng_event *event;
 807
 808         /* First ensure that probe events are created for this enabler. */
 809         lttng_create_event_if_missing(enabler);
 810
 811         /* For each event matching enabler in session event list. */
 812         cds_list_for_each_entry(event, &session->events_head, node) {
 813                 struct lttng_enabler_ref *enabler_ref;
 814
 815                 if (!lttng_event_match_enabler(event, enabler))
 816                         continue;
 817
 818                 enabler_ref = lttng_event_enabler_ref(event, enabler);
 819                 if (!enabler_ref) {
 820                         /*
 821                          * If no backward ref, create it.
 822                          * Add backward ref from event to enabler.
 823                          */
 824                         enabler_ref = zmalloc(sizeof(*enabler_ref));
 825                         if (!enabler_ref)
 826                                 return -ENOMEM;
 827                         enabler_ref->ref = enabler;
 828                         cds_list_add(&enabler_ref->node,
 829                                 &event->enablers_ref_head);
 830                 }
 831
 832                 /*
 833                  * Link filter bytecodes if not linked yet.
 834                  */
 835                 lttng_enabler_event_link_bytecode(event, enabler);
 836
 837                 /* TODO: merge event context. */
 838         }
 839         return 0;
 840 }
 841
 842 /*
 843  * Called at library load: connect the probe on all enablers matching
 844  * this event.
 845  * Called with session mutex held.
 846  */
 847 int lttng_fix_pending_events(void)
 848 {
 849         struct lttng_session *session;
 850
 851         cds_list_for_each_entry(session, &sessions, node) {
 852                 lttng_session_lazy_sync_enablers(session);
 853         }
 854         return 0;
 855 }
 856
 857 /*
 858  * For each session of the owner thread, execute pending statedump.
 859  * Only dump state for the sessions owned by the caller thread, because
 860  * we don't keep ust_lock across the entire iteration.
 861  */
 862 void lttng_handle_pending_statedump(void *owner)
 863 {
 864         struct lttng_session *session;
 865
 866         /* Execute state dump */
 867         do_lttng_ust_statedump(owner);
 868
 869         /* Clear pending state dump */
 870         if (ust_lock()) {
 871                 goto end;
 872         }
 873         cds_list_for_each_entry(session, &sessions, node) {
 874                 if (session->owner != owner)
 875                         continue;
 876                 if (!session->statedump_pending)
 877                         continue;
 878                 session->statedump_pending = 0;
 879         }
 880 end:
 881         ust_unlock();
 882         return;
 883 }
 884
 885 /*
 886  * Only used internally at session destruction.
 887  */
 888 static
 889 void _lttng_event_destroy(struct lttng_event *event)
 890 {
 891         struct lttng_enabler_ref *enabler_ref, *tmp_enabler_ref;
 892
 893         cds_list_del(&event->node);
 894         lttng_destroy_context(event->ctx);
 895         lttng_free_event_filter_runtime(event);
 896         /* Free event enabler refs */
 897         cds_list_for_each_entry_safe(enabler_ref, tmp_enabler_ref,
 898                         &event->enablers_ref_head, node)
 899                 free(enabler_ref);
 900         free(event);
 901 }
 902
 903 static
 904 void _lttng_enum_destroy(struct lttng_enum *_enum)
 905 {
 906         cds_list_del(&_enum->node);
 907         free(_enum);
 908 }
 909
 910 void lttng_ust_events_exit(void)
 911 {
 912         struct lttng_session *session, *tmpsession;
 913
 914         cds_list_for_each_entry_safe(session, tmpsession, &sessions, node)
 915                 lttng_session_destroy(session);
 916 }
 917
 918 /*
 919  * Enabler management.
 920  */
 921 struct lttng_enabler *lttng_enabler_create(enum lttng_enabler_type type,
 922                 struct lttng_ust_event *event_param,
 923                 struct lttng_channel *chan)
 924 {
 925         struct lttng_enabler *enabler;
 926
 927         enabler = zmalloc(sizeof(*enabler));
 928         if (!enabler)
 929                 return NULL;
 930         enabler->type = type;
 931         CDS_INIT_LIST_HEAD(&enabler->filter_bytecode_head);
 932         CDS_INIT_LIST_HEAD(&enabler->excluder_head);
 933         memcpy(&enabler->event_param, event_param,
 934                 sizeof(enabler->event_param));
 935         enabler->chan = chan;
 936         /* ctx left NULL */
 937         enabler->enabled = 0;
 938         cds_list_add(&enabler->node, &enabler->chan->session->enablers_head);
 939         lttng_session_lazy_sync_enablers(enabler->chan->session);
 940         return enabler;
 941 }
 942
 943 int lttng_enabler_enable(struct lttng_enabler *enabler)
 944 {
 945         enabler->enabled = 1;
 946         lttng_session_lazy_sync_enablers(enabler->chan->session);
 947         return 0;
 948 }
 949
 950 int lttng_enabler_disable(struct lttng_enabler *enabler)
 951 {
 952         enabler->enabled = 0;
 953         lttng_session_lazy_sync_enablers(enabler->chan->session);
 954         return 0;
 955 }
 956
 957 int lttng_enabler_attach_bytecode(struct lttng_enabler *enabler,
 958                 struct lttng_ust_filter_bytecode_node *bytecode)
 959 {
 960         bytecode->enabler = enabler;
 961         cds_list_add_tail(&bytecode->node, &enabler->filter_bytecode_head);
 962         lttng_session_lazy_sync_enablers(enabler->chan->session);
 963         return 0;
 964 }
 965
 966 int lttng_enabler_attach_exclusion(struct lttng_enabler *enabler,
 967                 struct lttng_ust_excluder_node *excluder)
 968 {
 969         excluder->enabler = enabler;
 970         cds_list_add_tail(&excluder->node, &enabler->excluder_head);
 971         lttng_session_lazy_sync_enablers(enabler->chan->session);
 972         return 0;
 973 }
 974
 975 int lttng_attach_context(struct lttng_ust_context *context_param,
 976                 union ust_args *uargs,
 977                 struct lttng_ctx **ctx, struct lttng_session *session)
 978 {
 979         /*
 980          * We cannot attach a context after trace has been started for a
 981          * session because the metadata does not allow expressing this
 982          * information outside of the original channel scope.
 983          */
 984         if (session->been_active)
 985                 return -EPERM;
 986
 987         switch (context_param->ctx) {
 988         case LTTNG_UST_CONTEXT_PTHREAD_ID:
 989                 return lttng_add_pthread_id_to_ctx(ctx);
 990         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
 991         {
 992                 struct lttng_ust_perf_counter_ctx *perf_ctx_param;
 993
 994                 perf_ctx_param = &context_param->u.perf_counter;
 995                 return lttng_add_perf_counter_to_ctx(
 996                         perf_ctx_param->type,
 997                         perf_ctx_param->config,
 998                         perf_ctx_param->name,
 999                         ctx);
1000         }
1001         case LTTNG_UST_CONTEXT_VTID:
1002                 return lttng_add_vtid_to_ctx(ctx);
1003         case LTTNG_UST_CONTEXT_VPID:
1004                 return lttng_add_vpid_to_ctx(ctx);
1005         case LTTNG_UST_CONTEXT_PROCNAME:
1006                 return lttng_add_procname_to_ctx(ctx);
1007         case LTTNG_UST_CONTEXT_IP:
1008                 return lttng_add_ip_to_ctx(ctx);
1009         case LTTNG_UST_CONTEXT_CPU_ID:
1010                 return lttng_add_cpu_id_to_ctx(ctx);
1011         case LTTNG_UST_CONTEXT_APP_CONTEXT:
1012                 return lttng_ust_add_app_context_to_ctx_rcu(uargs->app_context.ctxname,
1013                         ctx);
1014         default:
1015                 return -EINVAL;
1016         }
1017 }
1018
1019 int lttng_enabler_attach_context(struct lttng_enabler *enabler,
1020                 struct lttng_ust_context *context_param)
1021 {
1022 #if 0   // disabled for now.
1023         struct lttng_session *session = enabler->chan->session;
1024         int ret;
1025
1026         ret = lttng_attach_context(context_param, &enabler->ctx,
1027                         session);
1028         if (ret)
1029                 return ret;
1030         lttng_session_lazy_sync_enablers(enabler->chan->session);
1031 #endif
1032         return -ENOSYS;
1033 }
1034
1035 static
1036 void lttng_enabler_destroy(struct lttng_enabler *enabler)
1037 {
1038         struct lttng_ust_filter_bytecode_node *filter_node, *tmp_filter_node;
1039         struct lttng_ust_excluder_node *excluder_node, *tmp_excluder_node;
1040
1041         /* Destroy filter bytecode */
1042         cds_list_for_each_entry_safe(filter_node, tmp_filter_node,
1043                         &enabler->filter_bytecode_head, node) {
1044                 free(filter_node);
1045         }
1046
1047         /* Destroy excluders */
1048         cds_list_for_each_entry_safe(excluder_node, tmp_excluder_node,
1049                         &enabler->excluder_head, node) {
1050                 free(excluder_node);
1051         }
1052
1053         /* Destroy contexts */
1054         lttng_destroy_context(enabler->ctx);
1055
1056         cds_list_del(&enabler->node);
1057         free(enabler);
1058 }
1059
1060 /*
1061  * lttng_session_sync_enablers should be called just before starting a
1062  * session.
1063  */
1064 static
1065 void lttng_session_sync_enablers(struct lttng_session *session)
1066 {
1067         struct lttng_enabler *enabler;
1068         struct lttng_event *event;
1069
1070         cds_list_for_each_entry(enabler, &session->enablers_head, node)
1071                 lttng_enabler_ref_events(enabler);
1072         /*
1073          * For each event, if at least one of its enablers is enabled,
1074          * and its channel and session transient states are enabled, we
1075          * enable the event, else we disable it.
1076          */
1077         cds_list_for_each_entry(event, &session->events_head, node) {
1078                 struct lttng_enabler_ref *enabler_ref;
1079                 struct lttng_bytecode_runtime *runtime;
1080                 int enabled = 0, has_enablers_without_bytecode = 0;
1081
1082                 /* Enable events */
1083                 cds_list_for_each_entry(enabler_ref,
1084                                 &event->enablers_ref_head, node) {
1085                         if (enabler_ref->ref->enabled) {
1086                                 enabled = 1;
1087                                 break;
1088                         }
1089                 }
1090                 /*
1091                  * Enabled state is based on union of enablers, with
1092                  * intesection of session and channel transient enable
1093                  * states.
1094                  */
1095                 enabled = enabled && session->tstate && event->chan->tstate;
1096
1097                 CMM_STORE_SHARED(event->enabled, enabled);
1098                 /*
1099                  * Sync tracepoint registration with event enabled
1100                  * state.
1101                  */
1102                 if (enabled) {
1103                         if (!event->registered)
1104                                 register_event(event);
1105                 } else {
1106                         if (event->registered)
1107                                 unregister_event(event);
1108                 }
1109
1110                 /* Check if has enablers without bytecode enabled */
1111                 cds_list_for_each_entry(enabler_ref,
1112                                 &event->enablers_ref_head, node) {
1113                         if (enabler_ref->ref->enabled
1114                                         && cds_list_empty(&enabler_ref->ref->filter_bytecode_head)) {
1115                                 has_enablers_without_bytecode = 1;
1116                                 break;
1117                         }
1118                 }
1119                 event->has_enablers_without_bytecode =
1120                         has_enablers_without_bytecode;
1121
1122                 /* Enable filters */
1123                 cds_list_for_each_entry(runtime,
1124                                 &event->bytecode_runtime_head, node) {
1125                         lttng_filter_sync_state(runtime);
1126                 }
1127         }
1128 }
1129
1130 /*
1131  * Apply enablers to session events, adding events to session if need
1132  * be. It is required after each modification applied to an active
1133  * session, and right before session "start".
1134  * "lazy" sync means we only sync if required.
1135  */
1136 static
1137 void lttng_session_lazy_sync_enablers(struct lttng_session *session)
1138 {
1139         /* We can skip if session is not active */
1140         if (!session->active)
1141                 return;
1142         lttng_session_sync_enablers(session);
1143 }
1144
1145 /*
1146  * Update all sessions with the given app context.
1147  * Called with ust lock held.
1148  * This is invoked when an application context gets loaded/unloaded. It
1149  * ensures the context callbacks are in sync with the application
1150  * context (either app context callbacks, or dummy callbacks).
1151  */
1152 void lttng_ust_context_set_session_provider(const char *name,
1153                 size_t (*get_size)(struct lttng_ctx_field *field, size_t offset),
1154                 void (*record)(struct lttng_ctx_field *field,
1155                         struct lttng_ust_lib_ring_buffer_ctx *ctx,
1156                         struct lttng_channel *chan),
1157                 void (*get_value)(struct lttng_ctx_field *field,
1158                         struct lttng_ctx_value *value))
1159 {
1160         struct lttng_session *session;
1161
1162         cds_list_for_each_entry(session, &sessions, node) {
1163                 struct lttng_channel *chan;
1164                 struct lttng_event *event;
1165                 int ret;
1166
1167                 ret = lttng_ust_context_set_provider_rcu(&session->ctx,
1168                                 name, get_size, record, get_value);
1169                 if (ret)
1170                         abort();
1171                 cds_list_for_each_entry(chan, &session->chan_head, node) {
1172                         ret = lttng_ust_context_set_provider_rcu(&chan->ctx,
1173                                         name, get_size, record, get_value);
1174                         if (ret)
1175                                 abort();
1176                 }
1177                 cds_list_for_each_entry(event, &session->events_head, node) {
1178                         ret = lttng_ust_context_set_provider_rcu(&event->ctx,
1179                                         name, get_size, record, get_value);
1180                         if (ret)
1181                                 abort();
1182                 }
1183         }
1184 }