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 #include "ust-app.h"
  33
  34 /*
  35  * Match function for the events hash table lookup.
  36  *
  37  * Matches by name only. Used by the disable command.
  38  */
  39 int trace_ust_ht_match_event_by_name(struct cds_lfht_node *node,
  40                 const void *_key)
  41 {
  42         struct ltt_ust_event *event;
  43         const char *name;
  44
  45         assert(node);
  46         assert(_key);
  47
  48         event = caa_container_of(node, struct ltt_ust_event, node.node);
  49         name = _key;
  50
  51         /* Event name */
  52         if (strncmp(event->attr.name, name, sizeof(event->attr.name)) != 0) {
  53                 goto no_match;
  54         }
  55
  56         /* Match */
  57         return 1;
  58
  59 no_match:
  60         return 0;
  61 }
  62
  63 /*
  64  * Match function for the hash table lookup.
  65  *
  66  * It matches an ust event based on three attributes which are the event name,
  67  * the filter bytecode and the loglevel.
  68  */
  69 int trace_ust_ht_match_event(struct cds_lfht_node *node, const void *_key)
  70 {
  71         struct ltt_ust_event *event;
  72         const struct ltt_ust_ht_key *key;
  73         int ev_loglevel_value;
  74
  75         assert(node);
  76         assert(_key);
  77
  78         event = caa_container_of(node, struct ltt_ust_event, node.node);
  79         key = _key;
  80         ev_loglevel_value = event->attr.loglevel;
  81
  82         /* Match the 4 elements of the key: name, filter, loglevel, exclusions. */
  83
  84         /* Event name */
  85         if (strncmp(event->attr.name, key->name, sizeof(event->attr.name)) != 0) {
  86                 goto no_match;
  87         }
  88
  89         /* Event loglevel value and type. */
  90         if (event->attr.loglevel_type == key->loglevel_type) {
  91                 /* Same loglevel type. */
  92                 if (key->loglevel_type != LTTNG_UST_LOGLEVEL_ALL) {
  93                         /*
  94                          * Loglevel value must also match since the loglevel
  95                          * type is not all.
  96                          */
  97                         if (ev_loglevel_value != key->loglevel_value) {
  98                                 goto no_match;
  99                         }
 100                 }
 101         } else {
 102                 /* Loglevel type is different: no match. */
 103                 goto no_match;
 104         }
 105
 106         /* Only one of the filters is NULL, fail. */
 107         if ((key->filter && !event->filter) || (!key->filter && event->filter)) {
 108                 goto no_match;
 109         }
 110
 111         if (key->filter && event->filter) {
 112                 /* Both filters exists, check length followed by the bytecode. */
 113                 if (event->filter->len != key->filter->len ||
 114                                 memcmp(event->filter->data, key->filter->data,
 115                                         event->filter->len) != 0) {
 116                         goto no_match;
 117                 }
 118         }
 119
 120         /* If only one of the exclusions is NULL, fail. */
 121         if ((key->exclusion && !event->exclusion) || (!key->exclusion && event->exclusion)) {
 122                 goto no_match;
 123         }
 124
 125         if (key->exclusion && event->exclusion) {
 126                 /* Both exclusions exist; check count followed by names. */
 127                 if (event->exclusion->count != key->exclusion->count ||
 128                                 memcmp(event->exclusion->names, key->exclusion->names,
 129                                         event->exclusion->count * LTTNG_SYMBOL_NAME_LEN) != 0) {
 130                         goto no_match;
 131                 }
 132         }
 133         /* Match. */
 134         return 1;
 135
 136 no_match:
 137         return 0;
 138 }
 139
 140 /*
 141  * Find the channel in the hashtable and return channel pointer. RCU read side
 142  * lock MUST be acquired before calling this.
 143  */
 144 struct ltt_ust_channel *trace_ust_find_channel_by_name(struct lttng_ht *ht,
 145                 char *name)
 146 {
 147         struct lttng_ht_node_str *node;
 148         struct lttng_ht_iter iter;
 149
 150         /*
 151          * If we receive an empty string for channel name, it means the
 152          * default channel name is requested.
 153          */
 154         if (name[0] == '\0')
 155                 name = DEFAULT_CHANNEL_NAME;
 156
 157         lttng_ht_lookup(ht, (void *)name, &iter);
 158         node = lttng_ht_iter_get_node_str(&iter);
 159         if (node == NULL) {
 160                 goto error;
 161         }
 162
 163         DBG2("Trace UST channel %s found by name", name);
 164
 165         return caa_container_of(node, struct ltt_ust_channel, node);
 166
 167 error:
 168         DBG2("Trace UST channel %s not found by name", name);
 169         return NULL;
 170 }
 171
 172 /*
 173  * Find the event in the hashtable and return event pointer. RCU read side lock
 174  * MUST be acquired before calling this.
 175  */
 176 struct ltt_ust_event *trace_ust_find_event(struct lttng_ht *ht,
 177                 char *name, struct lttng_filter_bytecode *filter,
 178                 enum lttng_ust_loglevel_type loglevel_type, int loglevel_value,
 179                 struct lttng_event_exclusion *exclusion)
 180 {
 181         struct lttng_ht_node_str *node;
 182         struct lttng_ht_iter iter;
 183         struct ltt_ust_ht_key key;
 184
 185         assert(name);
 186         assert(ht);
 187
 188         key.name = name;
 189         key.filter = filter;
 190         key.loglevel_type = loglevel_type;
 191         key.loglevel_value = loglevel_value;
 192         key.exclusion = exclusion;
 193
 194         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 195                         trace_ust_ht_match_event, &key, &iter.iter);
 196         node = lttng_ht_iter_get_node_str(&iter);
 197         if (node == NULL) {
 198                 goto error;
 199         }
 200
 201         DBG2("Trace UST event %s found", key.name);
 202
 203         return caa_container_of(node, struct ltt_ust_event, node);
 204
 205 error:
 206         DBG2("Trace UST event %s NOT found", key.name);
 207         return NULL;
 208 }
 209
 210 /*
 211  * Lookup an agent in the session agents hash table by domain type and return
 212  * the object if found else NULL.
 213  *
 214  * RCU read side lock must be acquired before calling and only released
 215  * once the agent is no longer in scope or being used.
 216  */
 217 struct agent *trace_ust_find_agent(struct ltt_ust_session *session,
 218                 enum lttng_domain_type domain_type)
 219 {
 220         struct agent *agt = NULL;
 221         struct lttng_ht_node_u64 *node;
 222         struct lttng_ht_iter iter;
 223         uint64_t key;
 224
 225         assert(session);
 226
 227         DBG3("Trace ust agent lookup for domain %d", domain_type);
 228
 229         key = domain_type;
 230
 231         lttng_ht_lookup(session->agents, &key, &iter);
 232         node = lttng_ht_iter_get_node_u64(&iter);
 233         if (!node) {
 234                 goto end;
 235         }
 236         agt = caa_container_of(node, struct agent, node);
 237
 238 end:
 239         return agt;
 240 }
 241
 242 /*
 243  * Allocate and initialize a ust session data structure.
 244  *
 245  * Return pointer to structure or NULL.
 246  */
 247 struct ltt_ust_session *trace_ust_create_session(uint64_t session_id)
 248 {
 249         struct ltt_ust_session *lus;
 250
 251         /* Allocate a new ltt ust session */
 252         lus = zmalloc(sizeof(struct ltt_ust_session));
 253         if (lus == NULL) {
 254                 PERROR("create ust session zmalloc");
 255                 goto error;
 256         }
 257
 258         /* Init data structure */
 259         lus->id = session_id;
 260         lus->active = 0;
 261
 262         /* Set default metadata channel attribute. */
 263         lus->metadata_attr.overwrite = DEFAULT_CHANNEL_OVERWRITE;
 264         lus->metadata_attr.subbuf_size = default_get_metadata_subbuf_size();
 265         lus->metadata_attr.num_subbuf = DEFAULT_METADATA_SUBBUF_NUM;
 266         lus->metadata_attr.switch_timer_interval = DEFAULT_METADATA_SWITCH_TIMER;
 267         lus->metadata_attr.read_timer_interval = DEFAULT_METADATA_READ_TIMER;
 268         lus->metadata_attr.output = LTTNG_UST_MMAP;
 269
 270         /*
 271          * Default buffer type. This can be changed through an enable channel
 272          * requesting a different type. Note that this can only be changed once
 273          * during the session lifetime which is at the first enable channel and
 274          * only before start. The flag buffer_type_changed indicates the status.
 275          */
 276         lus->buffer_type = LTTNG_BUFFER_PER_UID;
 277         /* Once set to 1, the buffer_type is immutable for the session. */
 278         lus->buffer_type_changed = 0;
 279         /* Init it in case it get used after allocation. */
 280         CDS_INIT_LIST_HEAD(&lus->buffer_reg_uid_list);
 281
 282         /* Alloc UST global domain channels' HT */
 283         lus->domain_global.channels = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 284         /* Alloc agent hash table. */
 285         lus->agents = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
 286
 287         lus->consumer = consumer_create_output(CONSUMER_DST_LOCAL);
 288         if (lus->consumer == NULL) {
 289                 goto error_consumer;
 290         }
 291
 292         DBG2("UST trace session create successful");
 293
 294         return lus;
 295
 296 error_consumer:
 297         ht_cleanup_push(lus->domain_global.channels);
 298         ht_cleanup_push(lus->agents);
 299         free(lus);
 300 error:
 301         return NULL;
 302 }
 303
 304 /*
 305  * Allocate and initialize a ust channel data structure.
 306  *
 307  * Return pointer to structure or NULL.
 308  */
 309 struct ltt_ust_channel *trace_ust_create_channel(struct lttng_channel *chan,
 310                 enum lttng_domain_type domain)
 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         luc->domain = domain;
 323
 324         /* Copy UST channel attributes */
 325         luc->attr.overwrite = chan->attr.overwrite;
 326         luc->attr.subbuf_size = chan->attr.subbuf_size;
 327         luc->attr.num_subbuf = chan->attr.num_subbuf;
 328         luc->attr.switch_timer_interval = chan->attr.switch_timer_interval;
 329         luc->attr.read_timer_interval = chan->attr.read_timer_interval;
 330         luc->attr.output = (enum lttng_ust_output) chan->attr.output;
 331
 332         /* Translate to UST output enum */
 333         switch (luc->attr.output) {
 334         default:
 335                 luc->attr.output = LTTNG_UST_MMAP;
 336                 break;
 337         }
 338
 339         /*
 340          * If we receive an empty string for channel name, it means the
 341          * default channel name is requested.
 342          */
 343         if (chan->name[0] == '\0') {
 344                 strncpy(luc->name, DEFAULT_CHANNEL_NAME, sizeof(luc->name));
 345         } else {
 346                 /* Copy channel name */
 347                 strncpy(luc->name, chan->name, sizeof(luc->name));
 348         }
 349         luc->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 350
 351         /* Init node */
 352         lttng_ht_node_init_str(&luc->node, luc->name);
 353         CDS_INIT_LIST_HEAD(&luc->ctx_list);
 354
 355         /* Alloc hash tables */
 356         luc->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 357         luc->ctx = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
 358
 359         /* On-disk circular buffer parameters */
 360         luc->tracefile_size = chan->attr.tracefile_size;
 361         luc->tracefile_count = chan->attr.tracefile_count;
 362
 363         DBG2("Trace UST channel %s created", luc->name);
 364
 365 error:
 366         return luc;
 367 }
 368
 369 /*
 370  * Allocate and initialize a ust event. Set name and event type.
 371  * We own filter_expression, filter, and exclusion.
 372  *
 373  * Return pointer to structure or NULL.
 374  */
 375 struct ltt_ust_event *trace_ust_create_event(struct lttng_event *ev,
 376                 char *filter_expression,
 377                 struct lttng_filter_bytecode *filter,
 378                 struct lttng_event_exclusion *exclusion,
 379                 bool internal_event)
 380 {
 381         struct ltt_ust_event *lue;
 382
 383         assert(ev);
 384
 385         lue = zmalloc(sizeof(struct ltt_ust_event));
 386         if (lue == NULL) {
 387                 PERROR("ust event zmalloc");
 388                 goto error;
 389         }
 390
 391         lue->internal = internal_event;
 392
 393         switch (ev->type) {
 394         case LTTNG_EVENT_PROBE:
 395                 lue->attr.instrumentation = LTTNG_UST_PROBE;
 396                 break;
 397         case LTTNG_EVENT_FUNCTION:
 398                 lue->attr.instrumentation = LTTNG_UST_FUNCTION;
 399                 break;
 400         case LTTNG_EVENT_FUNCTION_ENTRY:
 401                 lue->attr.instrumentation = LTTNG_UST_FUNCTION;
 402                 break;
 403         case LTTNG_EVENT_TRACEPOINT:
 404                 lue->attr.instrumentation = LTTNG_UST_TRACEPOINT;
 405                 break;
 406         default:
 407                 ERR("Unknown ust instrumentation type (%d)", ev->type);
 408                 goto error_free_event;
 409         }
 410
 411         /* Copy event name */
 412         strncpy(lue->attr.name, ev->name, LTTNG_UST_SYM_NAME_LEN);
 413         lue->attr.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 414
 415         switch (ev->loglevel_type) {
 416         case LTTNG_EVENT_LOGLEVEL_ALL:
 417                 lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_ALL;
 418                 lue->attr.loglevel = -1;        /* Force to -1 */
 419                 break;
 420         case LTTNG_EVENT_LOGLEVEL_RANGE:
 421                 lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_RANGE;
 422                 lue->attr.loglevel = ev->loglevel;
 423                 break;
 424         case LTTNG_EVENT_LOGLEVEL_SINGLE:
 425                 lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_SINGLE;
 426                 lue->attr.loglevel = ev->loglevel;
 427                 break;
 428         default:
 429                 ERR("Unknown ust loglevel type (%d)", ev->loglevel_type);
 430                 goto error_free_event;
 431         }
 432
 433         /* Same layout. */
 434         lue->filter_expression = filter_expression;
 435         lue->filter = filter;
 436         lue->exclusion = exclusion;
 437
 438         /* Init node */
 439         lttng_ht_node_init_str(&lue->node, lue->attr.name);
 440
 441         DBG2("Trace UST event %s, loglevel (%d,%d) created",
 442                 lue->attr.name, lue->attr.loglevel_type,
 443                 lue->attr.loglevel);
 444
 445         return lue;
 446
 447 error_free_event:
 448         free(lue);
 449 error:
 450         free(filter_expression);
 451         free(filter);
 452         free(exclusion);
 453         return NULL;
 454 }
 455
 456 static
 457 int trace_ust_context_type_event_to_ust(enum lttng_event_context_type type)
 458 {
 459         int utype;
 460
 461         switch (type) {
 462         case LTTNG_EVENT_CONTEXT_VTID:
 463                 utype = LTTNG_UST_CONTEXT_VTID;
 464                 break;
 465         case LTTNG_EVENT_CONTEXT_VPID:
 466                 utype = LTTNG_UST_CONTEXT_VPID;
 467                 break;
 468         case LTTNG_EVENT_CONTEXT_PTHREAD_ID:
 469                 utype = LTTNG_UST_CONTEXT_PTHREAD_ID;
 470                 break;
 471         case LTTNG_EVENT_CONTEXT_PROCNAME:
 472                 utype = LTTNG_UST_CONTEXT_PROCNAME;
 473                 break;
 474         case LTTNG_EVENT_CONTEXT_IP:
 475                 utype = LTTNG_UST_CONTEXT_IP;
 476                 break;
 477         case LTTNG_EVENT_CONTEXT_PERF_THREAD_COUNTER:
 478                 if (!ustctl_has_perf_counters()) {
 479                         utype = -1;
 480                         WARN("Perf counters not implemented in UST");
 481                 } else {
 482                         utype = LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER;
 483                 }
 484                 break;
 485         default:
 486                 ERR("Invalid UST context");
 487                 utype = -1;
 488                 break;
 489         }
 490         return utype;
 491 }
 492
 493 /*
 494  * Return 1 if contexts match, 0 otherwise.
 495  */
 496 int trace_ust_match_context(struct ltt_ust_context *uctx,
 497                 struct lttng_event_context *ctx)
 498 {
 499         int utype;
 500
 501         utype = trace_ust_context_type_event_to_ust(ctx->ctx);
 502         if (utype < 0) {
 503                 return 0;
 504         }
 505         if (uctx->ctx.ctx != utype) {
 506                 return 0;
 507         }
 508         switch (utype) {
 509         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
 510                 if (uctx->ctx.u.perf_counter.type
 511                                 != ctx->u.perf_counter.type) {
 512                         return 0;
 513                 }
 514                 if (uctx->ctx.u.perf_counter.config
 515                                 != ctx->u.perf_counter.config) {
 516                         return 0;
 517                 }
 518                 if (strncmp(uctx->ctx.u.perf_counter.name,
 519                                 ctx->u.perf_counter.name,
 520                                 LTTNG_UST_SYM_NAME_LEN)) {
 521                         return 0;
 522                 }
 523                 break;
 524         default:
 525                 break;
 526
 527         }
 528         return 1;
 529 }
 530
 531 /*
 532  * Allocate and initialize an UST context.
 533  *
 534  * Return pointer to structure or NULL.
 535  */
 536 struct ltt_ust_context *trace_ust_create_context(
 537                 struct lttng_event_context *ctx)
 538 {
 539         struct ltt_ust_context *uctx;
 540         int utype;
 541
 542         assert(ctx);
 543
 544         utype = trace_ust_context_type_event_to_ust(ctx->ctx);
 545         if (utype < 0) {
 546                 return NULL;
 547         }
 548
 549         uctx = zmalloc(sizeof(struct ltt_ust_context));
 550         if (uctx == NULL) {
 551                 PERROR("zmalloc ltt_ust_context");
 552                 goto error;
 553         }
 554
 555         uctx->ctx.ctx = (enum lttng_ust_context_type) utype;
 556         switch (utype) {
 557         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
 558                 uctx->ctx.u.perf_counter.type = ctx->u.perf_counter.type;
 559                 uctx->ctx.u.perf_counter.config = ctx->u.perf_counter.config;
 560                 strncpy(uctx->ctx.u.perf_counter.name, ctx->u.perf_counter.name,
 561                                 LTTNG_UST_SYM_NAME_LEN);
 562                 uctx->ctx.u.perf_counter.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 563                 break;
 564         default:
 565                 break;
 566         }
 567         lttng_ht_node_init_ulong(&uctx->node, (unsigned long) uctx->ctx.ctx);
 568
 569         return uctx;
 570
 571 error:
 572         return NULL;
 573 }
 574
 575 static
 576 void destroy_pid_tracker_node_rcu(struct rcu_head *head)
 577 {
 578         struct ust_pid_tracker_node *tracker_node =
 579                 caa_container_of(head, struct ust_pid_tracker_node, node.head);
 580         free(tracker_node);
 581 }
 582
 583 static
 584 void destroy_pid_tracker_node(struct ust_pid_tracker_node *tracker_node)
 585 {
 586
 587         call_rcu(&tracker_node->node.head, destroy_pid_tracker_node_rcu);
 588 }
 589
 590 static
 591 int init_pid_tracker(struct ust_pid_tracker *pid_tracker)
 592 {
 593         int ret = 0;
 594
 595         pid_tracker->ht = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
 596         if (!pid_tracker->ht) {
 597                 ret = -1;
 598                 goto end;
 599         }
 600
 601 end:
 602         return ret;
 603 }
 604
 605 /*
 606  * Teardown pid tracker content, but don't free pid_tracker object.
 607  */
 608 static
 609 void fini_pid_tracker(struct ust_pid_tracker *pid_tracker)
 610 {
 611         struct ust_pid_tracker_node *tracker_node;
 612         struct lttng_ht_iter iter;
 613
 614         if (!pid_tracker->ht) {
 615                 return;
 616         }
 617         rcu_read_lock();
 618         cds_lfht_for_each_entry(pid_tracker->ht->ht,
 619                         &iter.iter, tracker_node, node.node) {
 620                 int ret = lttng_ht_del(pid_tracker->ht, &iter);
 621
 622                 assert(!ret);
 623                 destroy_pid_tracker_node(tracker_node);
 624         }
 625         rcu_read_unlock();
 626         ht_cleanup_push(pid_tracker->ht);
 627         pid_tracker->ht = NULL;
 628 }
 629
 630 static
 631 struct ust_pid_tracker_node *pid_tracker_lookup(
 632                 struct ust_pid_tracker *pid_tracker, int pid,
 633                 struct lttng_ht_iter *iter)
 634 {
 635         unsigned long _pid = (unsigned long) pid;
 636         struct lttng_ht_node_ulong *node;
 637
 638         lttng_ht_lookup(pid_tracker->ht, (void *) _pid, iter);
 639         node = lttng_ht_iter_get_node_ulong(iter);
 640         if (node) {
 641                 return caa_container_of(node, struct ust_pid_tracker_node,
 642                         node);
 643         } else {
 644                 return NULL;
 645         }
 646 }
 647
 648 static
 649 int pid_tracker_add_pid(struct ust_pid_tracker *pid_tracker, int pid)
 650 {
 651         int retval = LTTNG_OK;
 652         struct ust_pid_tracker_node *tracker_node;
 653         struct lttng_ht_iter iter;
 654
 655         if (pid < 0) {
 656                 retval = LTTNG_ERR_INVALID;
 657                 goto end;
 658         }
 659         tracker_node = pid_tracker_lookup(pid_tracker, pid, &iter);
 660         if (tracker_node) {
 661                 /* Already exists. */
 662                 retval = LTTNG_ERR_PID_TRACKED;
 663                 goto end;
 664         }
 665         tracker_node = zmalloc(sizeof(*tracker_node));
 666         if (!tracker_node) {
 667                 retval = LTTNG_ERR_NOMEM;
 668                 goto end;
 669         }
 670         lttng_ht_node_init_ulong(&tracker_node->node, (unsigned long) pid);
 671         lttng_ht_add_unique_ulong(pid_tracker->ht, &tracker_node->node);
 672 end:
 673         return retval;
 674 }
 675
 676 static
 677 int pid_tracker_del_pid(struct ust_pid_tracker *pid_tracker, int pid)
 678 {
 679         int retval = LTTNG_OK, ret;
 680         struct ust_pid_tracker_node *tracker_node;
 681         struct lttng_ht_iter iter;
 682
 683         if (pid < 0) {
 684                 retval = LTTNG_ERR_INVALID;
 685                 goto end;
 686         }
 687         tracker_node = pid_tracker_lookup(pid_tracker, pid, &iter);
 688         if (!tracker_node) {
 689                 /* Not found */
 690                 retval = LTTNG_ERR_PID_NOT_TRACKED;
 691                 goto end;
 692         }
 693         ret = lttng_ht_del(pid_tracker->ht, &iter);
 694         assert(!ret);
 695
 696         destroy_pid_tracker_node(tracker_node);
 697 end:
 698         return retval;
 699 }
 700
 701 /*
 702  * The session lock is held when calling this function.
 703  */
 704 int trace_ust_pid_tracker_lookup(struct ltt_ust_session *session, int pid)
 705 {
 706         struct lttng_ht_iter iter;
 707
 708         if (!session->pid_tracker.ht) {
 709                 return 1;
 710         }
 711         if (pid_tracker_lookup(&session->pid_tracker, pid, &iter)) {
 712                 return 1;
 713         }
 714         return 0;
 715 }
 716
 717 /*
 718  * Called with the session lock held.
 719  */
 720 int trace_ust_track_pid(struct ltt_ust_session *session, int pid)
 721 {
 722         int retval = LTTNG_OK;
 723
 724         if (pid == -1) {
 725                 /* Track all pids: destroy tracker if exists. */
 726                 if (session->pid_tracker.ht) {
 727                         fini_pid_tracker(&session->pid_tracker);
 728                         /* Ensure all apps have session. */
 729                         ust_app_global_update_all(session);
 730                 }
 731         } else {
 732                 int ret;
 733
 734                 if (!session->pid_tracker.ht) {
 735                         /* Create tracker. */
 736                         if (init_pid_tracker(&session->pid_tracker)) {
 737                                 ERR("Error initializing PID tracker");
 738                                 retval = LTTNG_ERR_NOMEM;
 739                                 goto end;
 740                         }
 741                         ret = pid_tracker_add_pid(&session->pid_tracker, pid);
 742                         if (ret != LTTNG_OK) {
 743                                 retval = ret;
 744                                 fini_pid_tracker(&session->pid_tracker);
 745                                 goto end;
 746                         }
 747                         /* Remove all apps from session except pid. */
 748                         ust_app_global_update_all(session);
 749                 } else {
 750                         struct ust_app *app;
 751
 752                         ret = pid_tracker_add_pid(&session->pid_tracker, pid);
 753                         if (ret != LTTNG_OK) {
 754                                 retval = ret;
 755                                 goto end;
 756                         }
 757                         /* Add session to application */
 758                         app = ust_app_find_by_pid(pid);
 759                         if (app) {
 760                                 ust_app_global_update(session, app);
 761                         }
 762                 }
 763         }
 764 end:
 765         return retval;
 766 }
 767
 768 /*
 769  * Called with the session lock held.
 770  */
 771 int trace_ust_untrack_pid(struct ltt_ust_session *session, int pid)
 772 {
 773         int retval = LTTNG_OK;
 774
 775         if (pid == -1) {
 776                 /* Create empty tracker, replace old tracker. */
 777                 struct ust_pid_tracker tmp_tracker;
 778
 779                 tmp_tracker = session->pid_tracker;
 780                 if (init_pid_tracker(&session->pid_tracker)) {
 781                         ERR("Error initializing PID tracker");
 782                         retval = LTTNG_ERR_NOMEM;
 783                         /* Rollback operation. */
 784                         session->pid_tracker = tmp_tracker;
 785                         goto end;
 786                 }
 787                 fini_pid_tracker(&tmp_tracker);
 788
 789                 /* Remove session from all applications */
 790                 ust_app_global_update_all(session);
 791         } else {
 792                 int ret;
 793                 struct ust_app *app;
 794
 795                 if (!session->pid_tracker.ht) {
 796                         /* No PID being tracked. */
 797                         retval = LTTNG_ERR_PID_NOT_TRACKED;
 798                         goto end;
 799                 }
 800                 /* Remove PID from tracker */
 801                 ret = pid_tracker_del_pid(&session->pid_tracker, pid);
 802                 if (ret != LTTNG_OK) {
 803                         retval = ret;
 804                         goto end;
 805                 }
 806                 /* Remove session from application. */
 807                 app = ust_app_find_by_pid(pid);
 808                 if (app) {
 809                         ust_app_global_update(session, app);
 810                 }
 811         }
 812 end:
 813         return retval;
 814 }
 815
 816 /*
 817  * Called with session lock held.
 818  */
 819 ssize_t trace_ust_list_tracker_pids(struct ltt_ust_session *session,
 820                 int32_t **_pids)
 821 {
 822         struct ust_pid_tracker_node *tracker_node;
 823         struct lttng_ht_iter iter;
 824         unsigned long count, i = 0;
 825         long approx[2];
 826         int32_t *pids;
 827         int ret = 0;
 828
 829         if (!session->pid_tracker.ht) {
 830                 /* Tracker disabled. Set first entry to -1. */
 831                 pids = zmalloc(sizeof(*pids));
 832                 if (!pids) {
 833                         ret = -1;
 834                         goto end;
 835                 }
 836                 pids[0] = -1;
 837                 *_pids = pids;
 838                 return 1;
 839         }
 840
 841         rcu_read_lock();
 842         cds_lfht_count_nodes(session->pid_tracker.ht->ht,
 843                 &approx[0], &count, &approx[1]);
 844         pids = zmalloc(sizeof(*pids) * count);
 845         if (!pids) {
 846                 ret = -1;
 847                 goto end;
 848         }
 849         cds_lfht_for_each_entry(session->pid_tracker.ht->ht,
 850                         &iter.iter, tracker_node, node.node) {
 851                 pids[i++] = tracker_node->node.key;
 852         }
 853         *_pids = pids;
 854         ret = count;
 855 end:
 856         rcu_read_unlock();
 857         return ret;
 858 }
 859
 860 /*
 861  * RCU safe free context structure.
 862  */
 863 static void destroy_context_rcu(struct rcu_head *head)
 864 {
 865         struct lttng_ht_node_ulong *node =
 866                 caa_container_of(head, struct lttng_ht_node_ulong, head);
 867         struct ltt_ust_context *ctx =
 868                 caa_container_of(node, struct ltt_ust_context, node);
 869
 870         free(ctx);
 871 }
 872
 873 /*
 874  * Cleanup UST context hash table.
 875  */
 876 static void destroy_contexts(struct lttng_ht *ht)
 877 {
 878         int ret;
 879         struct lttng_ht_node_ulong *node;
 880         struct lttng_ht_iter iter;
 881         struct ltt_ust_context *ctx;
 882
 883         assert(ht);
 884
 885         rcu_read_lock();
 886         cds_lfht_for_each_entry(ht->ht, &iter.iter, node, node) {
 887                 /* Remove from ordered list. */
 888                 ctx = caa_container_of(node, struct ltt_ust_context, node);
 889                 cds_list_del(&ctx->list);
 890                 /* Remove from channel's hash table. */
 891                 ret = lttng_ht_del(ht, &iter);
 892                 if (!ret) {
 893                         call_rcu(&node->head, destroy_context_rcu);
 894                 }
 895         }
 896         rcu_read_unlock();
 897
 898         ht_cleanup_push(ht);
 899 }
 900
 901 /*
 902  * Cleanup ust event structure.
 903  */
 904 void trace_ust_destroy_event(struct ltt_ust_event *event)
 905 {
 906         assert(event);
 907
 908         DBG2("Trace destroy UST event %s", event->attr.name);
 909         free(event->filter_expression);
 910         free(event->filter);
 911         free(event->exclusion);
 912         free(event);
 913 }
 914
 915 /*
 916  * URCU intermediate call to complete destroy event.
 917  */
 918 static void destroy_event_rcu(struct rcu_head *head)
 919 {
 920         struct lttng_ht_node_str *node =
 921                 caa_container_of(head, struct lttng_ht_node_str, head);
 922         struct ltt_ust_event *event =
 923                 caa_container_of(node, struct ltt_ust_event, node);
 924
 925         trace_ust_destroy_event(event);
 926 }
 927
 928 /*
 929  * Cleanup UST events hashtable.
 930  */
 931 static void destroy_events(struct lttng_ht *events)
 932 {
 933         int ret;
 934         struct lttng_ht_node_str *node;
 935         struct lttng_ht_iter iter;
 936
 937         assert(events);
 938
 939         rcu_read_lock();
 940         cds_lfht_for_each_entry(events->ht, &iter.iter, node, node) {
 941                 ret = lttng_ht_del(events, &iter);
 942                 assert(!ret);
 943                 call_rcu(&node->head, destroy_event_rcu);
 944         }
 945         rcu_read_unlock();
 946
 947         ht_cleanup_push(events);
 948 }
 949
 950 /*
 951  * Cleanup ust channel structure.
 952  *
 953  * Should _NOT_ be called with RCU read lock held.
 954  */
 955 static void _trace_ust_destroy_channel(struct ltt_ust_channel *channel)
 956 {
 957         assert(channel);
 958
 959         DBG2("Trace destroy UST channel %s", channel->name);
 960
 961         free(channel);
 962 }
 963
 964 /*
 965  * URCU intermediate call to complete destroy channel.
 966  */
 967 static void destroy_channel_rcu(struct rcu_head *head)
 968 {
 969         struct lttng_ht_node_str *node =
 970                 caa_container_of(head, struct lttng_ht_node_str, head);
 971         struct ltt_ust_channel *channel =
 972                 caa_container_of(node, struct ltt_ust_channel, node);
 973
 974         _trace_ust_destroy_channel(channel);
 975 }
 976
 977 void trace_ust_destroy_channel(struct ltt_ust_channel *channel)
 978 {
 979         /* Destroying all events of the channel */
 980         destroy_events(channel->events);
 981         /* Destroying all context of the channel */
 982         destroy_contexts(channel->ctx);
 983
 984         call_rcu(&channel->node.head, destroy_channel_rcu);
 985 }
 986
 987 /*
 988  * Remove an UST channel from a channel HT.
 989  */
 990 void trace_ust_delete_channel(struct lttng_ht *ht,
 991                 struct ltt_ust_channel *channel)
 992 {
 993         int ret;
 994         struct lttng_ht_iter iter;
 995
 996         assert(ht);
 997         assert(channel);
 998
 999         iter.iter.node = &channel->node.node;
1000         ret = lttng_ht_del(ht, &iter);
1001         assert(!ret);
1002 }
1003
1004 /*
1005  * Iterate over a hash table containing channels and cleanup safely.
1006  */
1007 static void destroy_channels(struct lttng_ht *channels)
1008 {
1009         struct lttng_ht_node_str *node;
1010         struct lttng_ht_iter iter;
1011
1012         assert(channels);
1013
1014         rcu_read_lock();
1015         cds_lfht_for_each_entry(channels->ht, &iter.iter, node, node) {
1016                 struct ltt_ust_channel *chan =
1017                         caa_container_of(node, struct ltt_ust_channel, node);
1018
1019                 trace_ust_delete_channel(channels, chan);
1020                 trace_ust_destroy_channel(chan);
1021         }
1022         rcu_read_unlock();
1023
1024         ht_cleanup_push(channels);
1025 }
1026
1027 /*
1028  * Cleanup UST global domain.
1029  */
1030 static void destroy_domain_global(struct ltt_ust_domain_global *dom)
1031 {
1032         assert(dom);
1033
1034         destroy_channels(dom->channels);
1035 }
1036
1037 /*
1038  * Cleanup ust session structure
1039  *
1040  * Should *NOT* be called with RCU read-side lock held.
1041  */
1042 void trace_ust_destroy_session(struct ltt_ust_session *session)
1043 {
1044         struct agent *agt;
1045         struct buffer_reg_uid *reg, *sreg;
1046         struct lttng_ht_iter iter;
1047
1048         assert(session);
1049
1050         DBG2("Trace UST destroy session %" PRIu64, session->id);
1051
1052         /* Cleaning up UST domain */
1053         destroy_domain_global(&session->domain_global);
1054
1055         rcu_read_lock();
1056         cds_lfht_for_each_entry(session->agents->ht, &iter.iter, agt, node.node) {
1057                 int ret = lttng_ht_del(session->agents, &iter);
1058
1059                 assert(!ret);
1060                 agent_destroy(agt);
1061         }
1062         rcu_read_unlock();
1063
1064         ht_cleanup_push(session->agents);
1065
1066         /* Cleanup UID buffer registry object(s). */
1067         cds_list_for_each_entry_safe(reg, sreg, &session->buffer_reg_uid_list,
1068                         lnode) {
1069                 cds_list_del(&reg->lnode);
1070                 buffer_reg_uid_remove(reg);
1071                 buffer_reg_uid_destroy(reg, session->consumer);
1072         }
1073
1074         consumer_output_put(session->consumer);
1075
1076         fini_pid_tracker(&session->pid_tracker);
1077
1078         free(session);
1079 }