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