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 #define _LGPL_SOURCE
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include <unistd.h>
  24 #include <inttypes.h>
  25
  26 #include <common/common.h>
  27 #include <common/defaults.h>
  28
  29 #include "buffer-registry.h"
  30 #include "trace-ust.h"
  31 #include "utils.h"
  32
  33 /*
  34  * Match function for the events hash table lookup.
  35  *
  36  * Matches by name only. Used by the disable command.
  37  */
  38 int trace_ust_ht_match_event_by_name(struct cds_lfht_node *node,
  39                 const void *_key)
  40 {
  41         struct ltt_ust_event *event;
  42         const char *name;
  43
  44         assert(node);
  45         assert(_key);
  46
  47         event = caa_container_of(node, struct ltt_ust_event, node.node);
  48         name = _key;
  49
  50         /* Event name */
  51         if (strncmp(event->attr.name, name, sizeof(event->attr.name)) != 0) {
  52                 goto no_match;
  53         }
  54
  55         /* Match */
  56         return 1;
  57
  58 no_match:
  59         return 0;
  60 }
  61
  62 /*
  63  * Match function for the hash table lookup.
  64  *
  65  * It matches an ust event based on three attributes which are the event name,
  66  * the filter bytecode and the loglevel.
  67  */
  68 int trace_ust_ht_match_event(struct cds_lfht_node *node, const void *_key)
  69 {
  70         struct ltt_ust_event *event;
  71         const struct ltt_ust_ht_key *key;
  72
  73         assert(node);
  74         assert(_key);
  75
  76         event = caa_container_of(node, struct ltt_ust_event, node.node);
  77         key = _key;
  78
  79         /* Match the 4 elements of the key: name, filter, loglevel, exclusions. */
  80
  81         /* Event name */
  82         if (strncmp(event->attr.name, key->name, sizeof(event->attr.name)) != 0) {
  83                 goto no_match;
  84         }
  85
  86         /* Event loglevel. */
  87         if (event->attr.loglevel != key->loglevel) {
  88                 if (event->attr.loglevel_type == LTTNG_UST_LOGLEVEL_ALL
  89                                 && key->loglevel == 0 && event->attr.loglevel == -1) {
  90                         /*
  91                          * Match is accepted. This is because on event creation, the
  92                          * loglevel is set to -1 if the event loglevel type is ALL so 0 and
  93                          * -1 are accepted for this loglevel type since 0 is the one set by
  94                          * the API when receiving an enable event.
  95                          */
  96                 } else {
  97                         goto no_match;
  98                 }
  99         }
 100
 101         /* Only one of the filters is NULL, fail. */
 102         if ((key->filter && !event->filter) || (!key->filter && event->filter)) {
 103                 goto no_match;
 104         }
 105
 106         if (key->filter && event->filter) {
 107                 /* Both filters exists, check length followed by the bytecode. */
 108                 if (event->filter->len != key->filter->len ||
 109                                 memcmp(event->filter->data, key->filter->data,
 110                                         event->filter->len) != 0) {
 111                         goto no_match;
 112                 }
 113         }
 114
 115         /* If only one of the exclusions is NULL, fail. */
 116         if ((key->exclusion && !event->exclusion) || (!key->exclusion && event->exclusion)) {
 117                 goto no_match;
 118         }
 119
 120         if (key->exclusion && event->exclusion) {
 121                 /* Both exclusions exist; check count followed by names. */
 122                 if (event->exclusion->count != key->exclusion->count ||
 123                                 memcmp(event->exclusion->names, key->exclusion->names,
 124                                         event->exclusion->count * LTTNG_SYMBOL_NAME_LEN) != 0) {
 125                         goto no_match;
 126                 }
 127         }
 128         /* Match. */
 129         return 1;
 130
 131 no_match:
 132         return 0;
 133 }
 134
 135 /*
 136  * Find the channel in the hashtable and return channel pointer. RCU read side
 137  * lock MUST be acquired before calling this.
 138  */
 139 struct ltt_ust_channel *trace_ust_find_channel_by_name(struct lttng_ht *ht,
 140                 char *name)
 141 {
 142         struct lttng_ht_node_str *node;
 143         struct lttng_ht_iter iter;
 144
 145         /*
 146          * If we receive an empty string for channel name, it means the
 147          * default channel name is requested.
 148          */
 149         if (name[0] == '\0')
 150                 name = DEFAULT_CHANNEL_NAME;
 151
 152         lttng_ht_lookup(ht, (void *)name, &iter);
 153         node = lttng_ht_iter_get_node_str(&iter);
 154         if (node == NULL) {
 155                 goto error;
 156         }
 157
 158         DBG2("Trace UST channel %s found by name", name);
 159
 160         return caa_container_of(node, struct ltt_ust_channel, node);
 161
 162 error:
 163         DBG2("Trace UST channel %s not found by name", name);
 164         return NULL;
 165 }
 166
 167 /*
 168  * Find the event in the hashtable and return event pointer. RCU read side lock
 169  * MUST be acquired before calling this.
 170  */
 171 struct ltt_ust_event *trace_ust_find_event(struct lttng_ht *ht,
 172                 char *name, struct lttng_filter_bytecode *filter, int loglevel,
 173                 struct lttng_event_exclusion *exclusion)
 174 {
 175         struct lttng_ht_node_str *node;
 176         struct lttng_ht_iter iter;
 177         struct ltt_ust_ht_key key;
 178
 179         assert(name);
 180         assert(ht);
 181
 182         key.name = name;
 183         key.filter = filter;
 184         key.loglevel = loglevel;
 185         key.exclusion = exclusion;
 186
 187         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 188                         trace_ust_ht_match_event, &key, &iter.iter);
 189         node = lttng_ht_iter_get_node_str(&iter);
 190         if (node == NULL) {
 191                 goto error;
 192         }
 193
 194         DBG2("Trace UST event %s found", key.name);
 195
 196         return caa_container_of(node, struct ltt_ust_event, node);
 197
 198 error:
 199         DBG2("Trace UST event %s NOT found", key.name);
 200         return NULL;
 201 }
 202
 203 /*
 204  * Lookup an agent in the session agents hash table by domain type and return
 205  * the object if found else NULL.
 206  *
 207  * RCU read side lock must be acquired before calling and only released
 208  * once the agent is no longer in scope or being used.
 209  */
 210 struct agent *trace_ust_find_agent(struct ltt_ust_session *session,
 211                 enum lttng_domain_type domain_type)
 212 {
 213         struct agent *agt = NULL;
 214         struct lttng_ht_node_u64 *node;
 215         struct lttng_ht_iter iter;
 216         uint64_t key;
 217
 218         assert(session);
 219
 220         DBG3("Trace ust agent lookup for domain %d", domain_type);
 221
 222         key = domain_type;
 223
 224         lttng_ht_lookup(session->agents, &key, &iter);
 225         node = lttng_ht_iter_get_node_u64(&iter);
 226         if (!node) {
 227                 goto end;
 228         }
 229         agt = caa_container_of(node, struct agent, node);
 230
 231 end:
 232         return agt;
 233 }
 234
 235 /*
 236  * Allocate and initialize a ust session data structure.
 237  *
 238  * Return pointer to structure or NULL.
 239  */
 240 struct ltt_ust_session *trace_ust_create_session(uint64_t session_id)
 241 {
 242         struct ltt_ust_session *lus;
 243
 244         /* Allocate a new ltt ust session */
 245         lus = zmalloc(sizeof(struct ltt_ust_session));
 246         if (lus == NULL) {
 247                 PERROR("create ust session zmalloc");
 248                 goto error;
 249         }
 250
 251         /* Init data structure */
 252         lus->id = session_id;
 253         lus->active = 0;
 254
 255         /* Set default metadata channel attribute. */
 256         lus->metadata_attr.overwrite = DEFAULT_CHANNEL_OVERWRITE;
 257         lus->metadata_attr.subbuf_size = default_get_metadata_subbuf_size();
 258         lus->metadata_attr.num_subbuf = DEFAULT_METADATA_SUBBUF_NUM;
 259         lus->metadata_attr.switch_timer_interval = DEFAULT_METADATA_SWITCH_TIMER;
 260         lus->metadata_attr.read_timer_interval = DEFAULT_METADATA_READ_TIMER;
 261         lus->metadata_attr.output = LTTNG_UST_MMAP;
 262
 263         /*
 264          * Default buffer type. This can be changed through an enable channel
 265          * requesting a different type. Note that this can only be changed once
 266          * during the session lifetime which is at the first enable channel and
 267          * only before start. The flag buffer_type_changed indicates the status.
 268          */
 269         lus->buffer_type = LTTNG_BUFFER_PER_UID;
 270         /* Once set to 1, the buffer_type is immutable for the session. */
 271         lus->buffer_type_changed = 0;
 272         /* Init it in case it get used after allocation. */
 273         CDS_INIT_LIST_HEAD(&lus->buffer_reg_uid_list);
 274
 275         /* Alloc UST global domain channels' HT */
 276         lus->domain_global.channels = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 277         /* Alloc agent hash table. */
 278         lus->agents = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
 279
 280         lus->consumer = consumer_create_output(CONSUMER_DST_LOCAL);
 281         if (lus->consumer == NULL) {
 282                 goto error_consumer;
 283         }
 284
 285         /*
 286          * The tmp_consumer stays NULL until a set_consumer_uri command is
 287          * executed. At this point, the consumer should be nullify until an
 288          * enable_consumer command. This assignment is symbolic since we've zmalloc
 289          * the struct.
 290          */
 291         lus->tmp_consumer = NULL;
 292
 293         DBG2("UST trace session create successful");
 294
 295         return lus;
 296
 297 error_consumer:
 298         ht_cleanup_push(lus->domain_global.channels);
 299         ht_cleanup_push(lus->agents);
 300         free(lus);
 301 error:
 302         return NULL;
 303 }
 304
 305 /*
 306  * Allocate and initialize a ust channel data structure.
 307  *
 308  * Return pointer to structure or NULL.
 309  */
 310 struct ltt_ust_channel *trace_ust_create_channel(struct lttng_channel *chan)
 311 {
 312         struct ltt_ust_channel *luc;
 313
 314         assert(chan);
 315
 316         luc = zmalloc(sizeof(struct ltt_ust_channel));
 317         if (luc == NULL) {
 318                 PERROR("ltt_ust_channel zmalloc");
 319                 goto error;
 320         }
 321
 322         /* Copy UST channel attributes */
 323         luc->attr.overwrite = chan->attr.overwrite;
 324         luc->attr.subbuf_size = chan->attr.subbuf_size;
 325         luc->attr.num_subbuf = chan->attr.num_subbuf;
 326         luc->attr.switch_timer_interval = chan->attr.switch_timer_interval;
 327         luc->attr.read_timer_interval = chan->attr.read_timer_interval;
 328         luc->attr.output = (enum lttng_ust_output) chan->attr.output;
 329
 330         /* Translate to UST output enum */
 331         switch (luc->attr.output) {
 332         default:
 333                 luc->attr.output = LTTNG_UST_MMAP;
 334                 break;
 335         }
 336
 337         /*
 338          * If we receive an empty string for channel name, it means the
 339          * default channel name is requested.
 340          */
 341         if (chan->name[0] == '\0') {
 342                 strncpy(luc->name, DEFAULT_CHANNEL_NAME, sizeof(luc->name));
 343         } else {
 344                 /* Copy channel name */
 345                 strncpy(luc->name, chan->name, sizeof(luc->name));
 346         }
 347         luc->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 348
 349         /* Init node */
 350         lttng_ht_node_init_str(&luc->node, luc->name);
 351         CDS_INIT_LIST_HEAD(&luc->ctx_list);
 352
 353         /* Alloc hash tables */
 354         luc->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 355         luc->ctx = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
 356
 357         /* On-disk circular buffer parameters */
 358         luc->tracefile_size = chan->attr.tracefile_size;
 359         luc->tracefile_count = chan->attr.tracefile_count;
 360
 361         DBG2("Trace UST channel %s created", luc->name);
 362
 363 error:
 364         return luc;
 365 }
 366
 367 /*
 368  * Allocate and initialize a ust event. Set name and event type.
 369  * We own filter_expression, filter, and exclusion.
 370  *
 371  * Return pointer to structure or NULL.
 372  */
 373 struct ltt_ust_event *trace_ust_create_event(struct lttng_event *ev,
 374                 char *filter_expression,
 375                 struct lttng_filter_bytecode *filter,
 376                 struct lttng_event_exclusion *exclusion)
 377 {
 378         struct ltt_ust_event *lue;
 379
 380         assert(ev);
 381
 382         lue = zmalloc(sizeof(struct ltt_ust_event));
 383         if (lue == NULL) {
 384                 PERROR("ust event zmalloc");
 385                 goto error;
 386         }
 387
 388         switch (ev->type) {
 389         case LTTNG_EVENT_PROBE:
 390                 lue->attr.instrumentation = LTTNG_UST_PROBE;
 391                 break;
 392         case LTTNG_EVENT_FUNCTION:
 393                 lue->attr.instrumentation = LTTNG_UST_FUNCTION;
 394                 break;
 395         case LTTNG_EVENT_FUNCTION_ENTRY:
 396                 lue->attr.instrumentation = LTTNG_UST_FUNCTION;
 397                 break;
 398         case LTTNG_EVENT_TRACEPOINT:
 399                 lue->attr.instrumentation = LTTNG_UST_TRACEPOINT;
 400                 break;
 401         default:
 402                 ERR("Unknown ust instrumentation type (%d)", ev->type);
 403                 goto error_free_event;
 404         }
 405
 406         /* Copy event name */
 407         strncpy(lue->attr.name, ev->name, LTTNG_UST_SYM_NAME_LEN);
 408         lue->attr.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 409
 410         switch (ev->loglevel_type) {
 411         case LTTNG_EVENT_LOGLEVEL_ALL:
 412                 lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_ALL;
 413                 lue->attr.loglevel = -1;        /* Force to -1 */
 414                 break;
 415         case LTTNG_EVENT_LOGLEVEL_RANGE:
 416                 lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_RANGE;
 417                 lue->attr.loglevel = ev->loglevel;
 418                 break;
 419         case LTTNG_EVENT_LOGLEVEL_SINGLE:
 420                 lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_SINGLE;
 421                 lue->attr.loglevel = ev->loglevel;
 422                 break;
 423         default:
 424                 ERR("Unknown ust loglevel type (%d)", ev->loglevel_type);
 425                 goto error_free_event;
 426         }
 427
 428         /* Same layout. */
 429         lue->filter_expression = filter_expression;
 430         lue->filter = (struct lttng_ust_filter_bytecode *) filter;
 431         lue->exclusion = (struct lttng_event_exclusion *) exclusion;
 432
 433         /* Init node */
 434         lttng_ht_node_init_str(&lue->node, lue->attr.name);
 435
 436         DBG2("Trace UST event %s, loglevel (%d,%d) created",
 437                 lue->attr.name, lue->attr.loglevel_type,
 438                 lue->attr.loglevel);
 439
 440         return lue;
 441
 442 error_free_event:
 443         free(lue);
 444 error:
 445         free(filter_expression);
 446         free(filter);
 447         free(exclusion);
 448         return NULL;
 449 }
 450
 451 static
 452 int trace_ust_context_type_event_to_ust(enum lttng_event_context_type type)
 453 {
 454         int utype;
 455
 456         switch (type) {
 457         case LTTNG_EVENT_CONTEXT_VTID:
 458                 utype = LTTNG_UST_CONTEXT_VTID;
 459                 break;
 460         case LTTNG_EVENT_CONTEXT_VPID:
 461                 utype = LTTNG_UST_CONTEXT_VPID;
 462                 break;
 463         case LTTNG_EVENT_CONTEXT_PTHREAD_ID:
 464                 utype = LTTNG_UST_CONTEXT_PTHREAD_ID;
 465                 break;
 466         case LTTNG_EVENT_CONTEXT_PROCNAME:
 467                 utype = LTTNG_UST_CONTEXT_PROCNAME;
 468                 break;
 469         case LTTNG_EVENT_CONTEXT_IP:
 470                 utype = LTTNG_UST_CONTEXT_IP;
 471                 break;
 472         case LTTNG_EVENT_CONTEXT_PERF_THREAD_COUNTER:
 473                 if (!ustctl_has_perf_counters()) {
 474                         utype = -1;
 475                         WARN("Perf counters not implemented in UST");
 476                 } else {
 477                         utype = LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER;
 478                 }
 479                 break;
 480         default:
 481                 ERR("Invalid UST context");
 482                 utype = -1;
 483                 break;
 484         }
 485         return utype;
 486 }
 487
 488 /*
 489  * Return 1 if contexts match, 0 otherwise.
 490  */
 491 int trace_ust_match_context(struct ltt_ust_context *uctx,
 492                 struct lttng_event_context *ctx)
 493 {
 494         int utype;
 495
 496         utype = trace_ust_context_type_event_to_ust(ctx->ctx);
 497         if (utype < 0) {
 498                 return 0;
 499         }
 500         if (uctx->ctx.ctx != utype) {
 501                 return 0;
 502         }
 503         switch (utype) {
 504         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
 505                 if (uctx->ctx.u.perf_counter.type
 506                                 != ctx->u.perf_counter.type) {
 507                         return 0;
 508                 }
 509                 if (uctx->ctx.u.perf_counter.config
 510                                 != ctx->u.perf_counter.config) {
 511                         return 0;
 512                 }
 513                 if (strncmp(uctx->ctx.u.perf_counter.name,
 514                                 ctx->u.perf_counter.name,
 515                                 LTTNG_UST_SYM_NAME_LEN)) {
 516                         return 0;
 517                 }
 518                 break;
 519         default:
 520                 break;
 521
 522         }
 523         return 1;
 524 }
 525
 526 /*
 527  * Allocate and initialize an UST context.
 528  *
 529  * Return pointer to structure or NULL.
 530  */
 531 struct ltt_ust_context *trace_ust_create_context(
 532                 struct lttng_event_context *ctx)
 533 {
 534         struct ltt_ust_context *uctx;
 535         int utype;
 536
 537         assert(ctx);
 538
 539         utype = trace_ust_context_type_event_to_ust(ctx->ctx);
 540         if (utype < 0) {
 541                 return NULL;
 542         }
 543
 544         uctx = zmalloc(sizeof(struct ltt_ust_context));
 545         if (uctx == NULL) {
 546                 PERROR("zmalloc ltt_ust_context");
 547                 goto error;
 548         }
 549
 550         uctx->ctx.ctx = (enum lttng_ust_context_type) utype;
 551         switch (utype) {
 552         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
 553                 uctx->ctx.u.perf_counter.type = ctx->u.perf_counter.type;
 554                 uctx->ctx.u.perf_counter.config = ctx->u.perf_counter.config;
 555                 strncpy(uctx->ctx.u.perf_counter.name, ctx->u.perf_counter.name,
 556                                 LTTNG_UST_SYM_NAME_LEN);
 557                 uctx->ctx.u.perf_counter.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 558                 break;
 559         default:
 560                 break;
 561         }
 562         lttng_ht_node_init_ulong(&uctx->node, (unsigned long) uctx->ctx.ctx);
 563
 564         return uctx;
 565
 566 error:
 567         return NULL;
 568 }
 569
 570 /*
 571  * RCU safe free context structure.
 572  */
 573 static void destroy_context_rcu(struct rcu_head *head)
 574 {
 575         struct lttng_ht_node_ulong *node =
 576                 caa_container_of(head, struct lttng_ht_node_ulong, head);
 577         struct ltt_ust_context *ctx =
 578                 caa_container_of(node, struct ltt_ust_context, node);
 579
 580         free(ctx);
 581 }
 582
 583 /*
 584  * Cleanup UST context hash table.
 585  */
 586 static void destroy_contexts(struct lttng_ht *ht)
 587 {
 588         int ret;
 589         struct lttng_ht_node_ulong *node;
 590         struct lttng_ht_iter iter;
 591         struct ltt_ust_context *ctx;
 592
 593         assert(ht);
 594
 595         rcu_read_lock();
 596         cds_lfht_for_each_entry(ht->ht, &iter.iter, node, node) {
 597                 /* Remove from ordered list. */
 598                 ctx = caa_container_of(node, struct ltt_ust_context, node);
 599                 cds_list_del(&ctx->list);
 600                 /* Remove from channel's hash table. */
 601                 ret = lttng_ht_del(ht, &iter);
 602                 if (!ret) {
 603                         call_rcu(&node->head, destroy_context_rcu);
 604                 }
 605         }
 606         rcu_read_unlock();
 607
 608         ht_cleanup_push(ht);
 609 }
 610
 611 /*
 612  * Cleanup ust event structure.
 613  */
 614 void trace_ust_destroy_event(struct ltt_ust_event *event)
 615 {
 616         assert(event);
 617
 618         DBG2("Trace destroy UST event %s", event->attr.name);
 619         free(event->filter_expression);
 620         free(event->filter);
 621         free(event->exclusion);
 622         free(event);
 623 }
 624
 625 /*
 626  * URCU intermediate call to complete destroy event.
 627  */
 628 static void destroy_event_rcu(struct rcu_head *head)
 629 {
 630         struct lttng_ht_node_str *node =
 631                 caa_container_of(head, struct lttng_ht_node_str, head);
 632         struct ltt_ust_event *event =
 633                 caa_container_of(node, struct ltt_ust_event, node);
 634
 635         trace_ust_destroy_event(event);
 636 }
 637
 638 /*
 639  * Cleanup UST events hashtable.
 640  */
 641 static void destroy_events(struct lttng_ht *events)
 642 {
 643         int ret;
 644         struct lttng_ht_node_str *node;
 645         struct lttng_ht_iter iter;
 646
 647         assert(events);
 648
 649         rcu_read_lock();
 650         cds_lfht_for_each_entry(events->ht, &iter.iter, node, node) {
 651                 ret = lttng_ht_del(events, &iter);
 652                 assert(!ret);
 653                 call_rcu(&node->head, destroy_event_rcu);
 654         }
 655         rcu_read_unlock();
 656
 657         ht_cleanup_push(events);
 658 }
 659
 660 /*
 661  * Cleanup ust channel structure.
 662  *
 663  * Should _NOT_ be called with RCU read lock held.
 664  */
 665 static void _trace_ust_destroy_channel(struct ltt_ust_channel *channel)
 666 {
 667         assert(channel);
 668
 669         DBG2("Trace destroy UST channel %s", channel->name);
 670
 671         /* Destroying all events of the channel */
 672         destroy_events(channel->events);
 673         /* Destroying all context of the channel */
 674         destroy_contexts(channel->ctx);
 675
 676         free(channel);
 677 }
 678
 679 /*
 680  * URCU intermediate call to complete destroy channel.
 681  */
 682 static void destroy_channel_rcu(struct rcu_head *head)
 683 {
 684         struct lttng_ht_node_str *node =
 685                 caa_container_of(head, struct lttng_ht_node_str, head);
 686         struct ltt_ust_channel *channel =
 687                 caa_container_of(node, struct ltt_ust_channel, node);
 688
 689         _trace_ust_destroy_channel(channel);
 690 }
 691
 692 void trace_ust_destroy_channel(struct ltt_ust_channel *channel)
 693 {
 694         call_rcu(&channel->node.head, destroy_channel_rcu);
 695 }
 696
 697 /*
 698  * Remove an UST channel from a channel HT.
 699  */
 700 void trace_ust_delete_channel(struct lttng_ht *ht,
 701                 struct ltt_ust_channel *channel)
 702 {
 703         int ret;
 704         struct lttng_ht_iter iter;
 705
 706         assert(ht);
 707         assert(channel);
 708
 709         iter.iter.node = &channel->node.node;
 710         ret = lttng_ht_del(ht, &iter);
 711         assert(!ret);
 712 }
 713
 714 /*
 715  * Iterate over a hash table containing channels and cleanup safely.
 716  */
 717 static void destroy_channels(struct lttng_ht *channels)
 718 {
 719         int ret;
 720         struct lttng_ht_node_str *node;
 721         struct lttng_ht_iter iter;
 722
 723         assert(channels);
 724
 725         rcu_read_lock();
 726
 727         cds_lfht_for_each_entry(channels->ht, &iter.iter, node, node) {
 728                 ret = lttng_ht_del(channels, &iter);
 729                 assert(!ret);
 730                 call_rcu(&node->head, destroy_channel_rcu);
 731         }
 732         rcu_read_unlock();
 733
 734         ht_cleanup_push(channels);
 735 }
 736
 737 /*
 738  * Cleanup UST global domain.
 739  */
 740 static void destroy_domain_global(struct ltt_ust_domain_global *dom)
 741 {
 742         assert(dom);
 743
 744         destroy_channels(dom->channels);
 745 }
 746
 747 /*
 748  * Cleanup ust session structure
 749  *
 750  * Should *NOT* be called with RCU read-side lock held.
 751  */
 752 void trace_ust_destroy_session(struct ltt_ust_session *session)
 753 {
 754         struct agent *agt;
 755         struct buffer_reg_uid *reg, *sreg;
 756         struct lttng_ht_iter iter;
 757
 758         assert(session);
 759
 760         DBG2("Trace UST destroy session %" PRIu64, session->id);
 761
 762         /* Cleaning up UST domain */
 763         destroy_domain_global(&session->domain_global);
 764
 765         rcu_read_lock();
 766         cds_lfht_for_each_entry(session->agents->ht, &iter.iter, agt, node.node) {
 767                 int ret = lttng_ht_del(session->agents, &iter);
 768
 769                 assert(!ret);
 770                 agent_destroy(agt);
 771         }
 772         rcu_read_unlock();
 773
 774         ht_cleanup_push(session->agents);
 775
 776         /* Cleanup UID buffer registry object(s). */
 777         cds_list_for_each_entry_safe(reg, sreg, &session->buffer_reg_uid_list,
 778                         lnode) {
 779                 cds_list_del(&reg->lnode);
 780                 buffer_reg_uid_remove(reg);
 781                 buffer_reg_uid_destroy(reg, session->consumer);
 782         }
 783
 784         consumer_destroy_output(session->consumer);
 785         consumer_destroy_output(session->tmp_consumer);
 786
 787         free(session);
 788 }