src/bin/lttng-sessiond/trace-ust.c

   1 /*
   2  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License, version 2 only,
   6  * as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _GNU_SOURCE
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <unistd.h>
  23 #include <inttypes.h>
  24
  25 #include <common/common.h>
  26 #include <common/defaults.h>
  27
  28 #include "buffer-registry.h"
  29 #include "trace-ust.h"
  30 #include "utils.h"
  31
  32 /*
  33  * Match function for the events hash table lookup.
  34  *
  35  * Matches by name only. Used by the disable command.
  36  */
  37 int trace_ust_ht_match_event_by_name(struct cds_lfht_node *node,
  38                 const void *_key)
  39 {
  40         struct ltt_ust_event *event;
  41         const char *name;
  42
  43         assert(node);
  44         assert(_key);
  45
  46         event = caa_container_of(node, struct ltt_ust_event, node.node);
  47         name = _key;
  48
  49         /* Event name */
  50         if (strncmp(event->attr.name, name, sizeof(event->attr.name)) != 0) {
  51                 goto no_match;
  52         }
  53
  54         /* Match */
  55         return 1;
  56
  57 no_match:
  58         return 0;
  59 }
  60
  61 /*
  62  * Match function for the hash table lookup.
  63  *
  64  * It matches an ust event based on three attributes which are the event name,
  65  * the filter bytecode and the loglevel.
  66  */
  67 int trace_ust_ht_match_event(struct cds_lfht_node *node, const void *_key)
  68 {
  69         struct ltt_ust_event *event;
  70         const struct ltt_ust_ht_key *key;
  71
  72         assert(node);
  73         assert(_key);
  74
  75         event = caa_container_of(node, struct ltt_ust_event, node.node);
  76         key = _key;
  77
  78         /* Match the 4 elements of the key: name, filter, loglevel, exclusions. */
  79
  80         /* Event name */
  81         if (strncmp(event->attr.name, key->name, sizeof(event->attr.name)) != 0) {
  82                 goto no_match;
  83         }
  84
  85         /* Event loglevel. */
  86         if (event->attr.loglevel != key->loglevel) {
  87                 if (event->attr.loglevel_type == LTTNG_UST_LOGLEVEL_ALL
  88                                 && key->loglevel == 0 && event->attr.loglevel == -1) {
  89                         /*
  90                          * Match is accepted. This is because on event creation, the
  91                          * loglevel is set to -1 if the event loglevel type is ALL so 0 and
  92                          * -1 are accepted for this loglevel type since 0 is the one set by
  93                          * the API when receiving an enable event.
  94                          */
  95                 } else {
  96                         goto no_match;
  97                 }
  98         }
  99
 100         /* Only one of the filters is NULL, fail. */
 101         if ((key->filter && !event->filter) || (!key->filter && event->filter)) {
 102                 goto no_match;
 103         }
 104
 105         if (key->filter && event->filter) {
 106                 /* Both filters exists, check length followed by the bytecode. */
 107                 if (event->filter->len != key->filter->len ||
 108                                 memcmp(event->filter->data, key->filter->data,
 109                                         event->filter->len) != 0) {
 110                         goto no_match;
 111                 }
 112         }
 113
 114         /* If only one of the exclusions is NULL, fail. */
 115         if ((key->exclusion && !event->exclusion) || (!key->exclusion && event->exclusion)) {
 116                 goto no_match;
 117         }
 118
 119         if (key->exclusion && event->exclusion) {
 120                 /* Both exclusions exist; check count followed by names. */
 121                 if (event->exclusion->count != key->exclusion->count ||
 122                                 memcmp(event->exclusion->names, key->exclusion->names,
 123                                         event->exclusion->count * LTTNG_SYMBOL_NAME_LEN) != 0) {
 124                         goto no_match;
 125                 }
 126         }
 127         /* Match. */
 128         return 1;
 129
 130 no_match:
 131         return 0;
 132 }
 133
 134 /*
 135  * Find the channel in the hashtable and return channel pointer. RCU read side
 136  * lock MUST be acquired before calling this.
 137  */
 138 struct ltt_ust_channel *trace_ust_find_channel_by_name(struct lttng_ht *ht,
 139                 char *name)
 140 {
 141         struct lttng_ht_node_str *node;
 142         struct lttng_ht_iter iter;
 143
 144         /*
 145          * If we receive an empty string for channel name, it means the
 146          * default channel name is requested.
 147          */
 148         if (name[0] == '\0')
 149                 name = DEFAULT_CHANNEL_NAME;
 150
 151         lttng_ht_lookup(ht, (void *)name, &iter);
 152         node = lttng_ht_iter_get_node_str(&iter);
 153         if (node == NULL) {
 154                 goto error;
 155         }
 156
 157         DBG2("Trace UST channel %s found by name", name);
 158
 159         return caa_container_of(node, struct ltt_ust_channel, node);
 160
 161 error:
 162         DBG2("Trace UST channel %s not found by name", name);
 163         return NULL;
 164 }
 165
 166 /*
 167  * Find the event in the hashtable and return event pointer. RCU read side lock
 168  * MUST be acquired before calling this.
 169  */
 170 struct ltt_ust_event *trace_ust_find_event(struct lttng_ht *ht,
 171                 char *name, struct lttng_filter_bytecode *filter, int loglevel,
 172                 struct lttng_event_exclusion *exclusion)
 173 {
 174         struct lttng_ht_node_str *node;
 175         struct lttng_ht_iter iter;
 176         struct ltt_ust_ht_key key;
 177
 178         assert(name);
 179         assert(ht);
 180
 181         key.name = name;
 182         key.filter = filter;
 183         key.loglevel = loglevel;
 184         key.exclusion = exclusion;
 185
 186         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 187                         trace_ust_ht_match_event, &key, &iter.iter);
 188         node = lttng_ht_iter_get_node_str(&iter);
 189         if (node == NULL) {
 190                 goto error;
 191         }
 192
 193         DBG2("Trace UST event %s found", key.name);
 194
 195         return caa_container_of(node, struct ltt_ust_event, node);
 196
 197 error:
 198         DBG2("Trace UST event %s NOT found", key.name);
 199         return NULL;
 200 }
 201
 202 /*
 203  * Lookup an agent in the session agents hash table by domain type and return
 204  * the object if found else NULL.
 205  *
 206  * RCU read side lock must be acquired before calling and only released
 207  * once the agent is no longer in scope or being used.
 208  */
 209 struct agent *trace_ust_find_agent(struct ltt_ust_session *session,
 210                 enum lttng_domain_type domain_type)
 211 {
 212         struct agent *agt = NULL;
 213         struct lttng_ht_node_u64 *node;
 214         struct lttng_ht_iter iter;
 215         uint64_t key;
 216
 217         assert(session);
 218
 219         DBG3("Trace ust agent lookup for domain %d", domain_type);
 220
 221         key = domain_type;
 222
 223         lttng_ht_lookup(session->agents, &key, &iter);
 224         node = lttng_ht_iter_get_node_u64(&iter);
 225         if (!node) {
 226                 goto end;
 227         }
 228         agt = caa_container_of(node, struct agent, node);
 229
 230 end:
 231         return agt;
 232 }
 233
 234 /*
 235  * Allocate and initialize a ust session data structure.
 236  *
 237  * Return pointer to structure or NULL.
 238  */
 239 struct ltt_ust_session *trace_ust_create_session(uint64_t session_id)
 240 {
 241         struct ltt_ust_session *lus;
 242
 243         /* Allocate a new ltt ust session */
 244         lus = zmalloc(sizeof(struct ltt_ust_session));
 245         if (lus == NULL) {
 246                 PERROR("create ust session zmalloc");
 247                 goto error;
 248         }
 249
 250         /* Init data structure */
 251         lus->id = session_id;
 252         lus->active = 0;
 253
 254         /* Set default metadata channel attribute. */
 255         lus->metadata_attr.overwrite = DEFAULT_CHANNEL_OVERWRITE;
 256         lus->metadata_attr.subbuf_size = default_get_metadata_subbuf_size();
 257         lus->metadata_attr.num_subbuf = DEFAULT_METADATA_SUBBUF_NUM;
 258         lus->metadata_attr.switch_timer_interval = DEFAULT_METADATA_SWITCH_TIMER;
 259         lus->metadata_attr.read_timer_interval = DEFAULT_METADATA_READ_TIMER;
 260         lus->metadata_attr.output = LTTNG_UST_MMAP;
 261
 262         /*
 263          * Default buffer type. This can be changed through an enable channel
 264          * requesting a different type. Note that this can only be changed once
 265          * during the session lifetime which is at the first enable channel and
 266          * only before start. The flag buffer_type_changed indicates the status.
 267          */
 268         lus->buffer_type = LTTNG_BUFFER_PER_UID;
 269         /* Once set to 1, the buffer_type is immutable for the session. */
 270         lus->buffer_type_changed = 0;
 271         /* Init it in case it get used after allocation. */
 272         CDS_INIT_LIST_HEAD(&lus->buffer_reg_uid_list);
 273
 274         /* Alloc UST global domain channels' HT */
 275         lus->domain_global.channels = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 276         /* Alloc agent hash table. */
 277         lus->agents = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
 278
 279         lus->consumer = consumer_create_output(CONSUMER_DST_LOCAL);
 280         if (lus->consumer == NULL) {
 281                 goto error_consumer;
 282         }
 283
 284         DBG2("UST trace session create successful");
 285
 286         return lus;
 287
 288 error_consumer:
 289         ht_cleanup_push(lus->domain_global.channels);
 290         ht_cleanup_push(lus->agents);
 291         free(lus);
 292 error:
 293         return NULL;
 294 }
 295
 296 /*
 297  * Allocate and initialize a ust channel data structure.
 298  *
 299  * Return pointer to structure or NULL.
 300  */
 301 struct ltt_ust_channel *trace_ust_create_channel(struct lttng_channel *chan)
 302 {
 303         struct ltt_ust_channel *luc;
 304
 305         assert(chan);
 306
 307         luc = zmalloc(sizeof(struct ltt_ust_channel));
 308         if (luc == NULL) {
 309                 PERROR("ltt_ust_channel zmalloc");
 310                 goto error;
 311         }
 312
 313         /* Copy UST channel attributes */
 314         luc->attr.overwrite = chan->attr.overwrite;
 315         luc->attr.subbuf_size = chan->attr.subbuf_size;
 316         luc->attr.num_subbuf = chan->attr.num_subbuf;
 317         luc->attr.switch_timer_interval = chan->attr.switch_timer_interval;
 318         luc->attr.read_timer_interval = chan->attr.read_timer_interval;
 319         luc->attr.output = (enum lttng_ust_output) chan->attr.output;
 320
 321         /* Translate to UST output enum */
 322         switch (luc->attr.output) {
 323         default:
 324                 luc->attr.output = LTTNG_UST_MMAP;
 325                 break;
 326         }
 327
 328         /*
 329          * If we receive an empty string for channel name, it means the
 330          * default channel name is requested.
 331          */
 332         if (chan->name[0] == '\0') {
 333                 strncpy(luc->name, DEFAULT_CHANNEL_NAME, sizeof(luc->name));
 334         } else {
 335                 /* Copy channel name */
 336                 strncpy(luc->name, chan->name, sizeof(luc->name));
 337         }
 338         luc->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 339
 340         /* Init node */
 341         lttng_ht_node_init_str(&luc->node, luc->name);
 342         CDS_INIT_LIST_HEAD(&luc->ctx_list);
 343
 344         /* Alloc hash tables */
 345         luc->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 346         luc->ctx = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
 347
 348         /* On-disk circular buffer parameters */
 349         luc->tracefile_size = chan->attr.tracefile_size;
 350         luc->tracefile_count = chan->attr.tracefile_count;
 351
 352         DBG2("Trace UST channel %s created", luc->name);
 353
 354 error:
 355         return luc;
 356 }
 357
 358 /*
 359  * Allocate and initialize a ust event. Set name and event type.
 360  * We own filter_expression, filter, and exclusion.
 361  *
 362  * Return pointer to structure or NULL.
 363  */
 364 struct ltt_ust_event *trace_ust_create_event(struct lttng_event *ev,
 365                 char *filter_expression,
 366                 struct lttng_filter_bytecode *filter,
 367                 struct lttng_event_exclusion *exclusion)
 368 {
 369         struct ltt_ust_event *lue;
 370
 371         assert(ev);
 372
 373         lue = zmalloc(sizeof(struct ltt_ust_event));
 374         if (lue == NULL) {
 375                 PERROR("ust event zmalloc");
 376                 goto error;
 377         }
 378
 379         switch (ev->type) {
 380         case LTTNG_EVENT_PROBE:
 381                 lue->attr.instrumentation = LTTNG_UST_PROBE;
 382                 break;
 383         case LTTNG_EVENT_FUNCTION:
 384                 lue->attr.instrumentation = LTTNG_UST_FUNCTION;
 385                 break;
 386         case LTTNG_EVENT_FUNCTION_ENTRY:
 387                 lue->attr.instrumentation = LTTNG_UST_FUNCTION;
 388                 break;
 389         case LTTNG_EVENT_TRACEPOINT:
 390                 lue->attr.instrumentation = LTTNG_UST_TRACEPOINT;
 391                 break;
 392         default:
 393                 ERR("Unknown ust instrumentation type (%d)", ev->type);
 394                 goto error_free_event;
 395         }
 396
 397         /* Copy event name */
 398         strncpy(lue->attr.name, ev->name, LTTNG_UST_SYM_NAME_LEN);
 399         lue->attr.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 400
 401         switch (ev->loglevel_type) {
 402         case LTTNG_EVENT_LOGLEVEL_ALL:
 403                 lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_ALL;
 404                 lue->attr.loglevel = -1;        /* Force to -1 */
 405                 break;
 406         case LTTNG_EVENT_LOGLEVEL_RANGE:
 407                 lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_RANGE;
 408                 lue->attr.loglevel = ev->loglevel;
 409                 break;
 410         case LTTNG_EVENT_LOGLEVEL_SINGLE:
 411                 lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_SINGLE;
 412                 lue->attr.loglevel = ev->loglevel;
 413                 break;
 414         default:
 415                 ERR("Unknown ust loglevel type (%d)", ev->loglevel_type);
 416                 goto error_free_event;
 417         }
 418         /*
 419          * Fix for enabler race. Enable is now done explicitly by
 420          * sessiond after setting filter.
 421          */
 422         lue->attr.disabled = 1;
 423
 424         /* Same layout. */
 425         lue->filter_expression = filter_expression;
 426         lue->filter = (struct lttng_ust_filter_bytecode *) filter;
 427         lue->exclusion = (struct lttng_event_exclusion *) exclusion;
 428
 429         /* Init node */
 430         lttng_ht_node_init_str(&lue->node, lue->attr.name);
 431
 432         DBG2("Trace UST event %s, loglevel (%d,%d) created",
 433                 lue->attr.name, lue->attr.loglevel_type,
 434                 lue->attr.loglevel);
 435
 436         return lue;
 437
 438 error_free_event:
 439         free(lue);
 440 error:
 441         free(filter_expression);
 442         free(filter);
 443         free(exclusion);
 444         return NULL;
 445 }
 446
 447 static
 448 int trace_ust_context_type_event_to_ust(enum lttng_event_context_type type)
 449 {
 450         int utype;
 451
 452         switch (type) {
 453         case LTTNG_EVENT_CONTEXT_VTID:
 454                 utype = LTTNG_UST_CONTEXT_VTID;
 455                 break;
 456         case LTTNG_EVENT_CONTEXT_VPID:
 457                 utype = LTTNG_UST_CONTEXT_VPID;
 458                 break;
 459         case LTTNG_EVENT_CONTEXT_PTHREAD_ID:
 460                 utype = LTTNG_UST_CONTEXT_PTHREAD_ID;
 461                 break;
 462         case LTTNG_EVENT_CONTEXT_PROCNAME:
 463                 utype = LTTNG_UST_CONTEXT_PROCNAME;
 464                 break;
 465         case LTTNG_EVENT_CONTEXT_IP:
 466                 utype = LTTNG_UST_CONTEXT_IP;
 467                 break;
 468         case LTTNG_EVENT_CONTEXT_PERF_THREAD_COUNTER:
 469                 if (!ustctl_has_perf_counters()) {
 470                         utype = -1;
 471                         WARN("Perf counters not implemented in UST");
 472                 } else {
 473                         utype = LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER;
 474                 }
 475                 break;
 476         default:
 477                 ERR("Invalid UST context");
 478                 utype = -1;
 479                 break;
 480         }
 481         return utype;
 482 }
 483
 484 /*
 485  * Return 1 if contexts match, 0 otherwise.
 486  */
 487 int trace_ust_match_context(struct ltt_ust_context *uctx,
 488                 struct lttng_event_context *ctx)
 489 {
 490         int utype;
 491
 492         utype = trace_ust_context_type_event_to_ust(ctx->ctx);
 493         if (utype < 0) {
 494                 return 0;
 495         }
 496         if (uctx->ctx.ctx != utype) {
 497                 return 0;
 498         }
 499         switch (utype) {
 500         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
 501                 if (uctx->ctx.u.perf_counter.type
 502                                 != ctx->u.perf_counter.type) {
 503                         return 0;
 504                 }
 505                 if (uctx->ctx.u.perf_counter.config
 506                                 != ctx->u.perf_counter.config) {
 507                         return 0;
 508                 }
 509                 if (strncmp(uctx->ctx.u.perf_counter.name,
 510                                 ctx->u.perf_counter.name,
 511                                 LTTNG_UST_SYM_NAME_LEN)) {
 512                         return 0;
 513                 }
 514                 break;
 515         default:
 516                 break;
 517
 518         }
 519         return 1;
 520 }
 521
 522 /*
 523  * Allocate and initialize an UST context.
 524  *
 525  * Return pointer to structure or NULL.
 526  */
 527 struct ltt_ust_context *trace_ust_create_context(
 528                 struct lttng_event_context *ctx)
 529 {
 530         struct ltt_ust_context *uctx;
 531         int utype;
 532
 533         assert(ctx);
 534
 535         utype = trace_ust_context_type_event_to_ust(ctx->ctx);
 536         if (utype < 0) {
 537                 return NULL;
 538         }
 539
 540         uctx = zmalloc(sizeof(struct ltt_ust_context));
 541         if (uctx == NULL) {
 542                 PERROR("zmalloc ltt_ust_context");
 543                 goto error;
 544         }
 545
 546         uctx->ctx.ctx = (enum lttng_ust_context_type) utype;
 547         switch (utype) {
 548         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
 549                 uctx->ctx.u.perf_counter.type = ctx->u.perf_counter.type;
 550                 uctx->ctx.u.perf_counter.config = ctx->u.perf_counter.config;
 551                 strncpy(uctx->ctx.u.perf_counter.name, ctx->u.perf_counter.name,
 552                                 LTTNG_UST_SYM_NAME_LEN);
 553                 uctx->ctx.u.perf_counter.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 554                 break;
 555         default:
 556                 break;
 557         }
 558         lttng_ht_node_init_ulong(&uctx->node, (unsigned long) uctx->ctx.ctx);
 559
 560         return uctx;
 561
 562 error:
 563         return NULL;
 564 }
 565
 566 /*
 567  * RCU safe free context structure.
 568  */
 569 static void destroy_context_rcu(struct rcu_head *head)
 570 {
 571         struct lttng_ht_node_ulong *node =
 572                 caa_container_of(head, struct lttng_ht_node_ulong, head);
 573         struct ltt_ust_context *ctx =
 574                 caa_container_of(node, struct ltt_ust_context, node);
 575
 576         free(ctx);
 577 }
 578
 579 /*
 580  * Cleanup UST context hash table.
 581  */
 582 static void destroy_contexts(struct lttng_ht *ht)
 583 {
 584         int ret;
 585         struct lttng_ht_node_ulong *node;
 586         struct lttng_ht_iter iter;
 587         struct ltt_ust_context *ctx;
 588
 589         assert(ht);
 590
 591         rcu_read_lock();
 592         cds_lfht_for_each_entry(ht->ht, &iter.iter, node, node) {
 593                 /* Remove from ordered list. */
 594                 ctx = caa_container_of(node, struct ltt_ust_context, node);
 595                 cds_list_del(&ctx->list);
 596                 /* Remove from channel's hash table. */
 597                 ret = lttng_ht_del(ht, &iter);
 598                 if (!ret) {
 599                         call_rcu(&node->head, destroy_context_rcu);
 600                 }
 601         }
 602         rcu_read_unlock();
 603
 604         ht_cleanup_push(ht);
 605 }
 606
 607 /*
 608  * Cleanup ust event structure.
 609  */
 610 void trace_ust_destroy_event(struct ltt_ust_event *event)
 611 {
 612         assert(event);
 613
 614         DBG2("Trace destroy UST event %s", event->attr.name);
 615         free(event->filter_expression);
 616         free(event->filter);
 617         free(event->exclusion);
 618         free(event);
 619 }
 620
 621 /*
 622  * URCU intermediate call to complete destroy event.
 623  */
 624 static void destroy_event_rcu(struct rcu_head *head)
 625 {
 626         struct lttng_ht_node_str *node =
 627                 caa_container_of(head, struct lttng_ht_node_str, head);
 628         struct ltt_ust_event *event =
 629                 caa_container_of(node, struct ltt_ust_event, node);
 630
 631         trace_ust_destroy_event(event);
 632 }
 633
 634 /*
 635  * Cleanup UST events hashtable.
 636  */
 637 static void destroy_events(struct lttng_ht *events)
 638 {
 639         int ret;
 640         struct lttng_ht_node_str *node;
 641         struct lttng_ht_iter iter;
 642
 643         assert(events);
 644
 645         rcu_read_lock();
 646         cds_lfht_for_each_entry(events->ht, &iter.iter, node, node) {
 647                 ret = lttng_ht_del(events, &iter);
 648                 assert(!ret);
 649                 call_rcu(&node->head, destroy_event_rcu);
 650         }
 651         rcu_read_unlock();
 652
 653         ht_cleanup_push(events);
 654 }
 655
 656 /*
 657  * Cleanup ust channel structure.
 658  *
 659  * Should _NOT_ be called with RCU read lock held.
 660  */
 661 static void _trace_ust_destroy_channel(struct ltt_ust_channel *channel)
 662 {
 663         assert(channel);
 664
 665         DBG2("Trace destroy UST channel %s", channel->name);
 666
 667         free(channel);
 668 }
 669
 670 /*
 671  * URCU intermediate call to complete destroy channel.
 672  */
 673 static void destroy_channel_rcu(struct rcu_head *head)
 674 {
 675         struct lttng_ht_node_str *node =
 676                 caa_container_of(head, struct lttng_ht_node_str, head);
 677         struct ltt_ust_channel *channel =
 678                 caa_container_of(node, struct ltt_ust_channel, node);
 679
 680         _trace_ust_destroy_channel(channel);
 681 }
 682
 683 void trace_ust_destroy_channel(struct ltt_ust_channel *channel)
 684 {
 685         /* Destroying all events of the channel */
 686         destroy_events(channel->events);
 687         /* Destroying all context of the channel */
 688         destroy_contexts(channel->ctx);
 689
 690         call_rcu(&channel->node.head, destroy_channel_rcu);
 691 }
 692
 693 /*
 694  * Remove an UST channel from a channel HT.
 695  */
 696 void trace_ust_delete_channel(struct lttng_ht *ht,
 697                 struct ltt_ust_channel *channel)
 698 {
 699         int ret;
 700         struct lttng_ht_iter iter;
 701
 702         assert(ht);
 703         assert(channel);
 704
 705         iter.iter.node = &channel->node.node;
 706         ret = lttng_ht_del(ht, &iter);
 707         assert(!ret);
 708 }
 709
 710 /*
 711  * Iterate over a hash table containing channels and cleanup safely.
 712  */
 713 static void destroy_channels(struct lttng_ht *channels)
 714 {
 715         struct lttng_ht_node_str *node;
 716         struct lttng_ht_iter iter;
 717
 718         assert(channels);
 719
 720         rcu_read_lock();
 721         cds_lfht_for_each_entry(channels->ht, &iter.iter, node, node) {
 722                 struct ltt_ust_channel *chan =
 723                         caa_container_of(node, struct ltt_ust_channel, node);
 724
 725                 trace_ust_delete_channel(channels, chan);
 726                 trace_ust_destroy_channel(chan);
 727         }
 728         rcu_read_unlock();
 729
 730         ht_cleanup_push(channels);
 731 }
 732
 733 /*
 734  * Cleanup UST global domain.
 735  */
 736 static void destroy_domain_global(struct ltt_ust_domain_global *dom)
 737 {
 738         assert(dom);
 739
 740         destroy_channels(dom->channels);
 741 }
 742
 743 /*
 744  * Cleanup ust session structure
 745  *
 746  * Should *NOT* be called with RCU read-side lock held.
 747  */
 748 void trace_ust_destroy_session(struct ltt_ust_session *session)
 749 {
 750         struct agent *agt;
 751         struct buffer_reg_uid *reg, *sreg;
 752         struct lttng_ht_iter iter;
 753
 754         assert(session);
 755
 756         DBG2("Trace UST destroy session %" PRIu64, session->id);
 757
 758         /* Cleaning up UST domain */
 759         destroy_domain_global(&session->domain_global);
 760
 761         rcu_read_lock();
 762         cds_lfht_for_each_entry(session->agents->ht, &iter.iter, agt, node.node) {
 763                 lttng_ht_del(session->agents, &iter);
 764                 agent_destroy(agt);
 765         }
 766         rcu_read_unlock();
 767
 768         /* Cleanup UID buffer registry object(s). */
 769         cds_list_for_each_entry_safe(reg, sreg, &session->buffer_reg_uid_list,
 770                         lnode) {
 771                 cds_list_del(&reg->lnode);
 772                 buffer_reg_uid_remove(reg);
 773                 buffer_reg_uid_destroy(reg, session->consumer);
 774         }
 775
 776         consumer_output_put(session->consumer);
 777
 778         free(session);
 779 }