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_queue_release(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_queue_release(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         __tracepoint_probe_prune_release_queue();
 234         cds_list_for_each_entry_safe(enabler, tmpenabler,
 235                         &session->enablers_head, node)
 236                 lttng_enabler_destroy(enabler);
 237         cds_list_for_each_entry_safe(event, tmpevent,
 238                         &session->events_head, node)
 239                 _lttng_event_destroy(event);
 240         cds_list_for_each_entry_safe(_enum, tmp_enum,
 241                         &session->enums_head, node)
 242                 _lttng_enum_destroy(_enum);
 243         cds_list_for_each_entry_safe(chan, tmpchan, &session->chan_head, node)
 244                 _lttng_channel_unmap(chan);
 245         cds_list_del(&session->node);
 246         lttng_destroy_context(session->ctx);
 247         free(session);
 248 }
 249
 250 static
 251 int lttng_enum_create(const struct lttng_enum_desc *desc,
 252                 struct lttng_session *session)
 253 {
 254         const char *enum_name = desc->name;
 255         struct lttng_enum *_enum;
 256         struct cds_hlist_head *head;
 257         struct cds_hlist_node *node;
 258         int ret = 0;
 259         size_t name_len = strlen(enum_name);
 260         uint32_t hash;
 261         int notify_socket;
 262
 263         hash = jhash(enum_name, name_len, 0);
 264         head = &session->enums_ht.table[hash & (LTTNG_UST_ENUM_HT_SIZE - 1)];
 265         cds_hlist_for_each_entry(_enum, node, head, hlist) {
 266                 assert(_enum->desc);
 267                 if (!strncmp(_enum->desc->name, desc->name,
 268                                 LTTNG_UST_SYM_NAME_LEN - 1)) {
 269                         ret = -EEXIST;
 270                         goto exist;
 271                 }
 272         }
 273
 274         notify_socket = lttng_get_notify_socket(session->owner);
 275         if (notify_socket < 0) {
 276                 ret = notify_socket;
 277                 goto socket_error;
 278         }
 279
 280         _enum = zmalloc(sizeof(*_enum));
 281         if (!_enum) {
 282                 ret = -ENOMEM;
 283                 goto cache_error;
 284         }
 285         _enum->session = session;
 286         _enum->desc = desc;
 287
 288         ret = ustcomm_register_enum(notify_socket,
 289                 session->objd,
 290                 enum_name,
 291                 desc->nr_entries,
 292                 desc->entries,
 293                 &_enum->id);
 294         if (ret < 0) {
 295                 DBG("Error (%d) registering enumeration to sessiond", ret);
 296                 goto sessiond_register_error;
 297         }
 298         cds_list_add(&_enum->node, &session->enums_head);
 299         cds_hlist_add_head(&_enum->hlist, head);
 300         return 0;
 301
 302 sessiond_register_error:
 303         free(_enum);
 304 cache_error:
 305 socket_error:
 306 exist:
 307         return ret;
 308 }
 309
 310 static
 311 int lttng_create_enum_check(const struct lttng_type *type,
 312                 struct lttng_session *session)
 313 {
 314         switch (type->atype) {
 315         case atype_enum:
 316         {
 317                 const struct lttng_enum_desc *enum_desc;
 318                 int ret;
 319
 320                 enum_desc = type->u.basic.enumeration.desc;
 321                 ret = lttng_enum_create(enum_desc, session);
 322                 if (ret && ret != -EEXIST) {
 323                         DBG("Unable to create enum error: (%d)", ret);
 324                         return ret;
 325                 }
 326                 break;
 327         }
 328         case atype_dynamic:
 329         {
 330                 const struct lttng_event_field *tag_field_generic;
 331                 const struct lttng_enum_desc *enum_desc;
 332                 int ret;
 333
 334                 tag_field_generic = lttng_ust_dynamic_type_tag_field();
 335                 enum_desc = tag_field_generic->type.u.basic.enumeration.desc;
 336                 ret = lttng_enum_create(enum_desc, session);
 337                 if (ret && ret != -EEXIST) {
 338                         DBG("Unable to create enum error: (%d)", ret);
 339                         return ret;
 340                 }
 341                 break;
 342         }
 343         default:
 344                 /* TODO: nested types when they become supported. */
 345                 break;
 346         }
 347         return 0;
 348 }
 349
 350 static
 351 int lttng_create_all_event_enums(size_t nr_fields,
 352                 const struct lttng_event_field *event_fields,
 353                 struct lttng_session *session)
 354 {
 355         size_t i;
 356         int ret;
 357
 358         /* For each field, ensure enum is part of the session. */
 359         for (i = 0; i < nr_fields; i++) {
 360                 const struct lttng_type *type = &event_fields[i].type;
 361
 362                 ret = lttng_create_enum_check(type, session);
 363                 if (ret)
 364                         return ret;
 365         }
 366         return 0;
 367 }
 368
 369 static
 370 int lttng_create_all_ctx_enums(size_t nr_fields,
 371                 const struct lttng_ctx_field *ctx_fields,
 372                 struct lttng_session *session)
 373 {
 374         size_t i;
 375         int ret;
 376
 377         /* For each field, ensure enum is part of the session. */
 378         for (i = 0; i < nr_fields; i++) {
 379                 const struct lttng_type *type = &ctx_fields[i].event_field.type;
 380
 381                 ret = lttng_create_enum_check(type, session);
 382                 if (ret)
 383                         return ret;
 384         }
 385         return 0;
 386 }
 387
 388 /*
 389  * Ensure that a state-dump will be performed for this session at the end
 390  * of the current handle_message().
 391  */
 392 int lttng_session_statedump(struct lttng_session *session)
 393 {
 394         session->statedump_pending = 1;
 395         lttng_ust_sockinfo_session_enabled(session->owner);
 396         return 0;
 397 }
 398
 399 int lttng_session_enable(struct lttng_session *session)
 400 {
 401         int ret = 0;
 402         struct lttng_channel *chan;
 403         int notify_socket;
 404
 405         if (session->active) {
 406                 ret = -EBUSY;
 407                 goto end;
 408         }
 409
 410         notify_socket = lttng_get_notify_socket(session->owner);
 411         if (notify_socket < 0)
 412                 return notify_socket;
 413
 414         /* Set transient enabler state to "enabled" */
 415         session->tstate = 1;
 416
 417         /*
 418          * Snapshot the number of events per channel to know the type of header
 419          * we need to use.
 420          */
 421         cds_list_for_each_entry(chan, &session->chan_head, node) {
 422                 const struct lttng_ctx *ctx;
 423                 const struct lttng_ctx_field *fields = NULL;
 424                 size_t nr_fields = 0;
 425                 uint32_t chan_id;
 426
 427                 /* don't change it if session stop/restart */
 428                 if (chan->header_type)
 429                         continue;
 430                 ctx = chan->ctx;
 431                 if (ctx) {
 432                         nr_fields = ctx->nr_fields;
 433                         fields = ctx->fields;
 434                         ret = lttng_create_all_ctx_enums(nr_fields, fields,
 435                                 session);
 436                         if (ret < 0) {
 437                                 DBG("Error (%d) adding enum to session", ret);
 438                                 return ret;
 439                         }
 440                 }
 441                 ret = ustcomm_register_channel(notify_socket,
 442                         session,
 443                         session->objd,
 444                         chan->objd,
 445                         nr_fields,
 446                         fields,
 447                         &chan_id,
 448                         &chan->header_type);
 449                 if (ret) {
 450                         DBG("Error (%d) registering channel to sessiond", ret);
 451                         return ret;
 452                 }
 453                 if (chan_id != chan->id) {
 454                         DBG("Error: channel registration id (%u) does not match id assigned at creation (%u)",
 455                                 chan_id, chan->id);
 456                         return -EINVAL;
 457                 }
 458         }
 459
 460         /* We need to sync enablers with session before activation. */
 461         lttng_session_sync_enablers(session);
 462
 463         /* Set atomically the state to "active" */
 464         CMM_ACCESS_ONCE(session->active) = 1;
 465         CMM_ACCESS_ONCE(session->been_active) = 1;
 466
 467         ret = lttng_session_statedump(session);
 468         if (ret)
 469                 return ret;
 470 end:
 471         return ret;
 472 }
 473
 474 int lttng_session_disable(struct lttng_session *session)
 475 {
 476         int ret = 0;
 477
 478         if (!session->active) {
 479                 ret = -EBUSY;
 480                 goto end;
 481         }
 482         /* Set atomically the state to "inactive" */
 483         CMM_ACCESS_ONCE(session->active) = 0;
 484
 485         /* Set transient enabler state to "disabled" */
 486         session->tstate = 0;
 487         lttng_session_sync_enablers(session);
 488 end:
 489         return ret;
 490 }
 491
 492 int lttng_channel_enable(struct lttng_channel *channel)
 493 {
 494         int ret = 0;
 495
 496         if (channel->enabled) {
 497                 ret = -EBUSY;
 498                 goto end;
 499         }
 500         /* Set transient enabler state to "enabled" */
 501         channel->tstate = 1;
 502         lttng_session_sync_enablers(channel->session);
 503         /* Set atomically the state to "enabled" */
 504         CMM_ACCESS_ONCE(channel->enabled) = 1;
 505 end:
 506         return ret;
 507 }
 508
 509 int lttng_channel_disable(struct lttng_channel *channel)
 510 {
 511         int ret = 0;
 512
 513         if (!channel->enabled) {
 514                 ret = -EBUSY;
 515                 goto end;
 516         }
 517         /* Set atomically the state to "disabled" */
 518         CMM_ACCESS_ONCE(channel->enabled) = 0;
 519         /* Set transient enabler state to "enabled" */
 520         channel->tstate = 0;
 521         lttng_session_sync_enablers(channel->session);
 522 end:
 523         return ret;
 524 }
 525
 526 /*
 527  * Supports event creation while tracing session is active.
 528  */
 529 static
 530 int lttng_event_create(const struct lttng_event_desc *desc,
 531                 struct lttng_channel *chan)
 532 {
 533         const char *event_name = desc->name;
 534         struct lttng_event *event;
 535         struct lttng_session *session = chan->session;
 536         struct cds_hlist_head *head;
 537         struct cds_hlist_node *node;
 538         int ret = 0;
 539         size_t name_len = strlen(event_name);
 540         uint32_t hash;
 541         int notify_socket, loglevel;
 542         const char *uri;
 543
 544         hash = jhash(event_name, name_len, 0);
 545         head = &chan->session->events_ht.table[hash & (LTTNG_UST_EVENT_HT_SIZE - 1)];
 546         cds_hlist_for_each_entry(event, node, head, hlist) {
 547                 assert(event->desc);
 548                 if (!strncmp(event->desc->name, desc->name,
 549                                         LTTNG_UST_SYM_NAME_LEN - 1)
 550                                 && chan == event->chan) {
 551                         ret = -EEXIST;
 552                         goto exist;
 553                 }
 554         }
 555
 556         notify_socket = lttng_get_notify_socket(session->owner);
 557         if (notify_socket < 0) {
 558                 ret = notify_socket;
 559                 goto socket_error;
 560         }
 561
 562         ret = lttng_create_all_event_enums(desc->nr_fields, desc->fields,
 563                         session);
 564         if (ret < 0) {
 565                 DBG("Error (%d) adding enum to session", ret);
 566                 goto create_enum_error;
 567         }
 568
 569         /*
 570          * Check if loglevel match. Refuse to connect event if not.
 571          */
 572         event = zmalloc(sizeof(struct lttng_event));
 573         if (!event) {
 574                 ret = -ENOMEM;
 575                 goto cache_error;
 576         }
 577         event->chan = chan;
 578
 579         /* Event will be enabled by enabler sync. */
 580         event->enabled = 0;
 581         event->registered = 0;
 582         CDS_INIT_LIST_HEAD(&event->bytecode_runtime_head);
 583         CDS_INIT_LIST_HEAD(&event->enablers_ref_head);
 584         event->desc = desc;
 585
 586         if (desc->loglevel)
 587                 loglevel = *(*event->desc->loglevel);
 588         else
 589                 loglevel = TRACE_DEFAULT;
 590         if (desc->u.ext.model_emf_uri)
 591                 uri = *(desc->u.ext.model_emf_uri);
 592         else
 593                 uri = NULL;
 594
 595         /* Fetch event ID from sessiond */
 596         ret = ustcomm_register_event(notify_socket,
 597                 session,
 598                 session->objd,
 599                 chan->objd,
 600                 event_name,
 601                 loglevel,
 602                 desc->signature,
 603                 desc->nr_fields,
 604                 desc->fields,
 605                 uri,
 606                 &event->id);
 607         if (ret < 0) {
 608                 DBG("Error (%d) registering event to sessiond", ret);
 609                 goto sessiond_register_error;
 610         }
 611
 612         /* Populate lttng_event structure before tracepoint registration. */
 613         cmm_smp_wmb();
 614         cds_list_add(&event->node, &chan->session->events_head);
 615         cds_hlist_add_head(&event->hlist, head);
 616         return 0;
 617
 618 sessiond_register_error:
 619         free(event);
 620 cache_error:
 621 create_enum_error:
 622 socket_error:
 623 exist:
 624         return ret;
 625 }
 626
 627 static
 628 int lttng_desc_match_wildcard_enabler(const struct lttng_event_desc *desc,
 629                 struct lttng_enabler *enabler)
 630 {
 631         int loglevel = 0;
 632         unsigned int has_loglevel = 0;
 633
 634         assert(enabler->type == LTTNG_ENABLER_WILDCARD);
 635         /* Compare excluding final '*' */
 636         if (strncmp(desc->name, enabler->event_param.name,
 637                         strlen(enabler->event_param.name) - 1))
 638                 return 0;
 639         if (desc->loglevel) {
 640                 loglevel = *(*desc->loglevel);
 641                 has_loglevel = 1;
 642         }
 643         if (!lttng_loglevel_match(loglevel,
 644                         has_loglevel,
 645                         enabler->event_param.loglevel_type,
 646                         enabler->event_param.loglevel))
 647                 return 0;
 648         return 1;
 649 }
 650
 651 static
 652 int lttng_desc_match_event_enabler(const struct lttng_event_desc *desc,
 653                 struct lttng_enabler *enabler)
 654 {
 655         int loglevel = 0;
 656         unsigned int has_loglevel = 0;
 657
 658         assert(enabler->type == LTTNG_ENABLER_EVENT);
 659         if (strcmp(desc->name, enabler->event_param.name))
 660                 return 0;
 661         if (desc->loglevel) {
 662                 loglevel = *(*desc->loglevel);
 663                 has_loglevel = 1;
 664         }
 665         if (!lttng_loglevel_match(loglevel,
 666                         has_loglevel,
 667                         enabler->event_param.loglevel_type,
 668                         enabler->event_param.loglevel))
 669                 return 0;
 670         return 1;
 671 }
 672
 673 static
 674 int lttng_desc_match_enabler(const struct lttng_event_desc *desc,
 675                 struct lttng_enabler *enabler)
 676 {
 677         struct lttng_ust_excluder_node *excluder;
 678
 679         /* If event matches with an excluder, return 'does not match' */
 680         cds_list_for_each_entry(excluder, &enabler->excluder_head, node) {
 681                 int count;
 682
 683                 for (count = 0; count < excluder->excluder.count; count++) {
 684                         int found, len;
 685                         char *excluder_name;
 686
 687                         excluder_name = (char *) (excluder->excluder.names)
 688                                         + count * LTTNG_UST_SYM_NAME_LEN;
 689                         len = strnlen(excluder_name, LTTNG_UST_SYM_NAME_LEN);
 690                         if (len > 0 && excluder_name[len - 1] == '*') {
 691                                 found = !strncmp(desc->name, excluder_name,
 692                                                 len - 1);
 693                         } else {
 694                                 found = !strncmp(desc->name, excluder_name,
 695                                                 LTTNG_UST_SYM_NAME_LEN - 1);
 696                         }
 697                         if (found) {
 698                                 return 0;
 699                         }
 700                 }
 701         }
 702         switch (enabler->type) {
 703         case LTTNG_ENABLER_WILDCARD:
 704                 return lttng_desc_match_wildcard_enabler(desc, enabler);
 705         case LTTNG_ENABLER_EVENT:
 706                 return lttng_desc_match_event_enabler(desc, enabler);
 707         default:
 708                 return -EINVAL;
 709         }
 710 }
 711
 712 static
 713 int lttng_event_match_enabler(struct lttng_event *event,
 714                 struct lttng_enabler *enabler)
 715 {
 716         if (lttng_desc_match_enabler(event->desc, enabler)
 717                         && event->chan == enabler->chan)
 718                 return 1;
 719         else
 720                 return 0;
 721 }
 722
 723 static
 724 struct lttng_enabler_ref * lttng_event_enabler_ref(struct lttng_event *event,
 725                 struct lttng_enabler *enabler)
 726 {
 727         struct lttng_enabler_ref *enabler_ref;
 728
 729         cds_list_for_each_entry(enabler_ref,
 730                         &event->enablers_ref_head, node) {
 731                 if (enabler_ref->ref == enabler)
 732                         return enabler_ref;
 733         }
 734         return NULL;
 735 }
 736
 737 /*
 738  * Create struct lttng_event if it is missing and present in the list of
 739  * tracepoint probes.
 740  */
 741 static
 742 void lttng_create_event_if_missing(struct lttng_enabler *enabler)
 743 {
 744         struct lttng_session *session = enabler->chan->session;
 745         struct lttng_probe_desc *probe_desc;
 746         const struct lttng_event_desc *desc;
 747         struct lttng_event *event;
 748         int i;
 749         struct cds_list_head *probe_list;
 750
 751         probe_list = lttng_get_probe_list_head();
 752         /*
 753          * For each probe event, if we find that a probe event matches
 754          * our enabler, create an associated lttng_event if not
 755          * already present.
 756          */
 757         cds_list_for_each_entry(probe_desc, probe_list, head) {
 758                 for (i = 0; i < probe_desc->nr_events; i++) {
 759                         int found = 0, ret;
 760                         struct cds_hlist_head *head;
 761                         struct cds_hlist_node *node;
 762                         const char *event_name;
 763                         size_t name_len;
 764                         uint32_t hash;
 765
 766                         desc = probe_desc->event_desc[i];
 767                         if (!lttng_desc_match_enabler(desc, enabler))
 768                                 continue;
 769                         event_name = desc->name;
 770                         name_len = strlen(event_name);
 771
 772                         /*
 773                          * Check if already created.
 774                          */
 775                         hash = jhash(event_name, name_len, 0);
 776                         head = &session->events_ht.table[hash & (LTTNG_UST_EVENT_HT_SIZE - 1)];
 777                         cds_hlist_for_each_entry(event, node, head, hlist) {
 778                                 if (event->desc == desc
 779                                                 && event->chan == enabler->chan)
 780                                         found = 1;
 781                         }
 782                         if (found)
 783                                 continue;
 784
 785                         /*
 786                          * We need to create an event for this
 787                          * event probe.
 788                          */
 789                         ret = lttng_event_create(probe_desc->event_desc[i],
 790                                         enabler->chan);
 791                         if (ret) {
 792                                 DBG("Unable to create event %s, error %d\n",
 793                                         probe_desc->event_desc[i]->name, ret);
 794                         }
 795                 }
 796         }
 797 }
 798
 799 /*
 800  * Create events associated with an enabler (if not already present),
 801  * and add backward reference from the event to the enabler.
 802  */
 803 static
 804 int lttng_enabler_ref_events(struct lttng_enabler *enabler)
 805 {
 806         struct lttng_session *session = enabler->chan->session;
 807         struct lttng_event *event;
 808
 809         /* First ensure that probe events are created for this enabler. */
 810         lttng_create_event_if_missing(enabler);
 811
 812         /* For each event matching enabler in session event list. */
 813         cds_list_for_each_entry(event, &session->events_head, node) {
 814                 struct lttng_enabler_ref *enabler_ref;
 815
 816                 if (!lttng_event_match_enabler(event, enabler))
 817                         continue;
 818
 819                 enabler_ref = lttng_event_enabler_ref(event, enabler);
 820                 if (!enabler_ref) {
 821                         /*
 822                          * If no backward ref, create it.
 823                          * Add backward ref from event to enabler.
 824                          */
 825                         enabler_ref = zmalloc(sizeof(*enabler_ref));
 826                         if (!enabler_ref)
 827                                 return -ENOMEM;
 828                         enabler_ref->ref = enabler;
 829                         cds_list_add(&enabler_ref->node,
 830                                 &event->enablers_ref_head);
 831                 }
 832
 833                 /*
 834                  * Link filter bytecodes if not linked yet.
 835                  */
 836                 lttng_enabler_event_link_bytecode(event, enabler);
 837
 838                 /* TODO: merge event context. */
 839         }
 840         return 0;
 841 }
 842
 843 /*
 844  * Called at library load: connect the probe on all enablers matching
 845  * this event.
 846  * Called with session mutex held.
 847  */
 848 int lttng_fix_pending_events(void)
 849 {
 850         struct lttng_session *session;
 851
 852         cds_list_for_each_entry(session, &sessions, node) {
 853                 lttng_session_lazy_sync_enablers(session);
 854         }
 855         return 0;
 856 }
 857
 858 /*
 859  * For each session of the owner thread, execute pending statedump.
 860  * Only dump state for the sessions owned by the caller thread, because
 861  * we don't keep ust_lock across the entire iteration.
 862  */
 863 void lttng_handle_pending_statedump(void *owner)
 864 {
 865         struct lttng_session *session;
 866
 867         /* Execute state dump */
 868         do_lttng_ust_statedump(owner);
 869
 870         /* Clear pending state dump */
 871         if (ust_lock()) {
 872                 goto end;
 873         }
 874         cds_list_for_each_entry(session, &sessions, node) {
 875                 if (session->owner != owner)
 876                         continue;
 877                 if (!session->statedump_pending)
 878                         continue;
 879                 session->statedump_pending = 0;
 880         }
 881 end:
 882         ust_unlock();
 883         return;
 884 }
 885
 886 /*
 887  * Only used internally at session destruction.
 888  */
 889 static
 890 void _lttng_event_destroy(struct lttng_event *event)
 891 {
 892         struct lttng_enabler_ref *enabler_ref, *tmp_enabler_ref;
 893
 894         cds_list_del(&event->node);
 895         lttng_destroy_context(event->ctx);
 896         lttng_free_event_filter_runtime(event);
 897         /* Free event enabler refs */
 898         cds_list_for_each_entry_safe(enabler_ref, tmp_enabler_ref,
 899                         &event->enablers_ref_head, node)
 900                 free(enabler_ref);
 901         free(event);
 902 }
 903
 904 static
 905 void _lttng_enum_destroy(struct lttng_enum *_enum)
 906 {
 907         cds_list_del(&_enum->node);
 908         free(_enum);
 909 }
 910
 911 void lttng_ust_events_exit(void)
 912 {
 913         struct lttng_session *session, *tmpsession;
 914
 915         cds_list_for_each_entry_safe(session, tmpsession, &sessions, node)
 916                 lttng_session_destroy(session);
 917 }
 918
 919 /*
 920  * Enabler management.
 921  */
 922 struct lttng_enabler *lttng_enabler_create(enum lttng_enabler_type type,
 923                 struct lttng_ust_event *event_param,
 924                 struct lttng_channel *chan)
 925 {
 926         struct lttng_enabler *enabler;
 927
 928         enabler = zmalloc(sizeof(*enabler));
 929         if (!enabler)
 930                 return NULL;
 931         enabler->type = type;
 932         CDS_INIT_LIST_HEAD(&enabler->filter_bytecode_head);
 933         CDS_INIT_LIST_HEAD(&enabler->excluder_head);
 934         memcpy(&enabler->event_param, event_param,
 935                 sizeof(enabler->event_param));
 936         enabler->chan = chan;
 937         /* ctx left NULL */
 938         enabler->enabled = 0;
 939         cds_list_add(&enabler->node, &enabler->chan->session->enablers_head);
 940         lttng_session_lazy_sync_enablers(enabler->chan->session);
 941         return enabler;
 942 }
 943
 944 int lttng_enabler_enable(struct lttng_enabler *enabler)
 945 {
 946         enabler->enabled = 1;
 947         lttng_session_lazy_sync_enablers(enabler->chan->session);
 948         return 0;
 949 }
 950
 951 int lttng_enabler_disable(struct lttng_enabler *enabler)
 952 {
 953         enabler->enabled = 0;
 954         lttng_session_lazy_sync_enablers(enabler->chan->session);
 955         return 0;
 956 }
 957
 958 int lttng_enabler_attach_bytecode(struct lttng_enabler *enabler,
 959                 struct lttng_ust_filter_bytecode_node *bytecode)
 960 {
 961         bytecode->enabler = enabler;
 962         cds_list_add_tail(&bytecode->node, &enabler->filter_bytecode_head);
 963         lttng_session_lazy_sync_enablers(enabler->chan->session);
 964         return 0;
 965 }
 966
 967 int lttng_enabler_attach_exclusion(struct lttng_enabler *enabler,
 968                 struct lttng_ust_excluder_node *excluder)
 969 {
 970         excluder->enabler = enabler;
 971         cds_list_add_tail(&excluder->node, &enabler->excluder_head);
 972         lttng_session_lazy_sync_enablers(enabler->chan->session);
 973         return 0;
 974 }
 975
 976 int lttng_attach_context(struct lttng_ust_context *context_param,
 977                 union ust_args *uargs,
 978                 struct lttng_ctx **ctx, struct lttng_session *session)
 979 {
 980         /*
 981          * We cannot attach a context after trace has been started for a
 982          * session because the metadata does not allow expressing this
 983          * information outside of the original channel scope.
 984          */
 985         if (session->been_active)
 986                 return -EPERM;
 987
 988         switch (context_param->ctx) {
 989         case LTTNG_UST_CONTEXT_PTHREAD_ID:
 990                 return lttng_add_pthread_id_to_ctx(ctx);
 991         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
 992         {
 993                 struct lttng_ust_perf_counter_ctx *perf_ctx_param;
 994
 995                 perf_ctx_param = &context_param->u.perf_counter;
 996                 return lttng_add_perf_counter_to_ctx(
 997                         perf_ctx_param->type,
 998                         perf_ctx_param->config,
 999                         perf_ctx_param->name,
1000                         ctx);
1001         }
1002         case LTTNG_UST_CONTEXT_VTID:
1003                 return lttng_add_vtid_to_ctx(ctx);
1004         case LTTNG_UST_CONTEXT_VPID:
1005                 return lttng_add_vpid_to_ctx(ctx);
1006         case LTTNG_UST_CONTEXT_PROCNAME:
1007                 return lttng_add_procname_to_ctx(ctx);
1008         case LTTNG_UST_CONTEXT_IP:
1009                 return lttng_add_ip_to_ctx(ctx);
1010         case LTTNG_UST_CONTEXT_CPU_ID:
1011                 return lttng_add_cpu_id_to_ctx(ctx);
1012         case LTTNG_UST_CONTEXT_APP_CONTEXT:
1013                 return lttng_ust_add_app_context_to_ctx_rcu(uargs->app_context.ctxname,
1014                         ctx);
1015         default:
1016                 return -EINVAL;
1017         }
1018 }
1019
1020 int lttng_enabler_attach_context(struct lttng_enabler *enabler,
1021                 struct lttng_ust_context *context_param)
1022 {
1023 #if 0   // disabled for now.
1024         struct lttng_session *session = enabler->chan->session;
1025         int ret;
1026
1027         ret = lttng_attach_context(context_param, &enabler->ctx,
1028                         session);
1029         if (ret)
1030                 return ret;
1031         lttng_session_lazy_sync_enablers(enabler->chan->session);
1032 #endif
1033         return -ENOSYS;
1034 }
1035
1036 static
1037 void lttng_enabler_destroy(struct lttng_enabler *enabler)
1038 {
1039         struct lttng_ust_filter_bytecode_node *filter_node, *tmp_filter_node;
1040         struct lttng_ust_excluder_node *excluder_node, *tmp_excluder_node;
1041
1042         /* Destroy filter bytecode */
1043         cds_list_for_each_entry_safe(filter_node, tmp_filter_node,
1044                         &enabler->filter_bytecode_head, node) {
1045                 free(filter_node);
1046         }
1047
1048         /* Destroy excluders */
1049         cds_list_for_each_entry_safe(excluder_node, tmp_excluder_node,
1050                         &enabler->excluder_head, node) {
1051                 free(excluder_node);
1052         }
1053
1054         /* Destroy contexts */
1055         lttng_destroy_context(enabler->ctx);
1056
1057         cds_list_del(&enabler->node);
1058         free(enabler);
1059 }
1060
1061 /*
1062  * lttng_session_sync_enablers should be called just before starting a
1063  * session.
1064  */
1065 static
1066 void lttng_session_sync_enablers(struct lttng_session *session)
1067 {
1068         struct lttng_enabler *enabler;
1069         struct lttng_event *event;
1070
1071         cds_list_for_each_entry(enabler, &session->enablers_head, node)
1072                 lttng_enabler_ref_events(enabler);
1073         /*
1074          * For each event, if at least one of its enablers is enabled,
1075          * and its channel and session transient states are enabled, we
1076          * enable the event, else we disable it.
1077          */
1078         cds_list_for_each_entry(event, &session->events_head, node) {
1079                 struct lttng_enabler_ref *enabler_ref;
1080                 struct lttng_bytecode_runtime *runtime;
1081                 int enabled = 0, has_enablers_without_bytecode = 0;
1082
1083                 /* Enable events */
1084                 cds_list_for_each_entry(enabler_ref,
1085                                 &event->enablers_ref_head, node) {
1086                         if (enabler_ref->ref->enabled) {
1087                                 enabled = 1;
1088                                 break;
1089                         }
1090                 }
1091                 /*
1092                  * Enabled state is based on union of enablers, with
1093                  * intesection of session and channel transient enable
1094                  * states.
1095                  */
1096                 enabled = enabled && session->tstate && event->chan->tstate;
1097
1098                 CMM_STORE_SHARED(event->enabled, enabled);
1099                 /*
1100                  * Sync tracepoint registration with event enabled
1101                  * state.
1102                  */
1103                 if (enabled) {
1104                         if (!event->registered)
1105                                 register_event(event);
1106                 } else {
1107                         if (event->registered)
1108                                 unregister_event(event);
1109                 }
1110
1111                 /* Check if has enablers without bytecode enabled */
1112                 cds_list_for_each_entry(enabler_ref,
1113                                 &event->enablers_ref_head, node) {
1114                         if (enabler_ref->ref->enabled
1115                                         && cds_list_empty(&enabler_ref->ref->filter_bytecode_head)) {
1116                                 has_enablers_without_bytecode = 1;
1117                                 break;
1118                         }
1119                 }
1120                 event->has_enablers_without_bytecode =
1121                         has_enablers_without_bytecode;
1122
1123                 /* Enable filters */
1124                 cds_list_for_each_entry(runtime,
1125                                 &event->bytecode_runtime_head, node) {
1126                         lttng_filter_sync_state(runtime);
1127                 }
1128         }
1129         __tracepoint_probe_prune_release_queue();
1130 }
1131
1132 /*
1133  * Apply enablers to session events, adding events to session if need
1134  * be. It is required after each modification applied to an active
1135  * session, and right before session "start".
1136  * "lazy" sync means we only sync if required.
1137  */
1138 static
1139 void lttng_session_lazy_sync_enablers(struct lttng_session *session)
1140 {
1141         /* We can skip if session is not active */
1142         if (!session->active)
1143                 return;
1144         lttng_session_sync_enablers(session);
1145 }
1146
1147 /*
1148  * Update all sessions with the given app context.
1149  * Called with ust lock held.
1150  * This is invoked when an application context gets loaded/unloaded. It
1151  * ensures the context callbacks are in sync with the application
1152  * context (either app context callbacks, or dummy callbacks).
1153  */
1154 void lttng_ust_context_set_session_provider(const char *name,
1155                 size_t (*get_size)(struct lttng_ctx_field *field, size_t offset),
1156                 void (*record)(struct lttng_ctx_field *field,
1157                         struct lttng_ust_lib_ring_buffer_ctx *ctx,
1158                         struct lttng_channel *chan),
1159                 void (*get_value)(struct lttng_ctx_field *field,
1160                         struct lttng_ctx_value *value))
1161 {
1162         struct lttng_session *session;
1163
1164         cds_list_for_each_entry(session, &sessions, node) {
1165                 struct lttng_channel *chan;
1166                 struct lttng_event *event;
1167                 int ret;
1168
1169                 ret = lttng_ust_context_set_provider_rcu(&session->ctx,
1170                                 name, get_size, record, get_value);
1171                 if (ret)
1172                         abort();
1173                 cds_list_for_each_entry(chan, &session->chan_head, node) {
1174                         ret = lttng_ust_context_set_provider_rcu(&chan->ctx,
1175                                         name, get_size, record, get_value);
1176                         if (ret)
1177                                 abort();
1178                 }
1179                 cds_list_for_each_entry(event, &session->events_head, node) {
1180                         ret = lttng_ust_context_set_provider_rcu(&event->ctx,
1181                                         name, get_size, record, get_value);
1182                         if (ret)
1183                                 abort();
1184                 }
1185         }
1186 }