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 _LGPL_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 #include "ust-app.h"
  32 #include "agent.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         int ll_match;
  75
  76         assert(node);
  77         assert(_key);
  78
  79         event = caa_container_of(node, struct ltt_ust_event, node.node);
  80         key = _key;
  81         ev_loglevel_value = event->attr.loglevel;
  82
  83         /* Match the 4 elements of the key: name, filter, loglevel, exclusions. */
  84
  85         /* Event name */
  86         if (strncmp(event->attr.name, key->name, sizeof(event->attr.name)) != 0) {
  87                 goto no_match;
  88         }
  89
  90         /* Event loglevel value and type. */
  91         ll_match = loglevels_match(event->attr.loglevel_type,
  92                 ev_loglevel_value, key->loglevel_type,
  93                 key->loglevel_value, LTTNG_UST_LOGLEVEL_ALL);
  94
  95         if (!ll_match) {
  96                 goto no_match;
  97         }
  98
  99         /* Only one of the filters is NULL, fail. */
 100         if ((key->filter && !event->filter) || (!key->filter && event->filter)) {
 101                 goto no_match;
 102         }
 103
 104         if (key->filter && event->filter) {
 105                 /* Both filters exists, check length followed by the bytecode. */
 106                 if (event->filter->len != key->filter->len ||
 107                                 memcmp(event->filter->data, key->filter->data,
 108                                         event->filter->len) != 0) {
 109                         goto no_match;
 110                 }
 111         }
 112
 113         /* If only one of the exclusions is NULL, fail. */
 114         if ((key->exclusion && !event->exclusion) || (!key->exclusion && event->exclusion)) {
 115                 goto no_match;
 116         }
 117
 118         if (key->exclusion && event->exclusion) {
 119                 /* Both exclusions exist; check count followed by names. */
 120                 if (event->exclusion->count != key->exclusion->count ||
 121                                 memcmp(event->exclusion->names, key->exclusion->names,
 122                                         event->exclusion->count * LTTNG_SYMBOL_NAME_LEN) != 0) {
 123                         goto no_match;
 124                 }
 125         }
 126         /* Match. */
 127         return 1;
 128
 129 no_match:
 130         return 0;
 131 }
 132
 133 /*
 134  * Find the channel in the hashtable and return channel pointer. RCU read side
 135  * lock MUST be acquired before calling this.
 136  */
 137 struct ltt_ust_channel *trace_ust_find_channel_by_name(struct lttng_ht *ht,
 138                 char *name)
 139 {
 140         struct lttng_ht_node_str *node;
 141         struct lttng_ht_iter iter;
 142
 143         /*
 144          * If we receive an empty string for channel name, it means the
 145          * default channel name is requested.
 146          */
 147         if (name[0] == '\0')
 148                 name = DEFAULT_CHANNEL_NAME;
 149
 150         lttng_ht_lookup(ht, (void *)name, &iter);
 151         node = lttng_ht_iter_get_node_str(&iter);
 152         if (node == NULL) {
 153                 goto error;
 154         }
 155
 156         DBG2("Trace UST channel %s found by name", name);
 157
 158         return caa_container_of(node, struct ltt_ust_channel, node);
 159
 160 error:
 161         DBG2("Trace UST channel %s not found by name", name);
 162         return NULL;
 163 }
 164
 165 /*
 166  * Find the event in the hashtable and return event pointer. RCU read side lock
 167  * MUST be acquired before calling this.
 168  */
 169 struct ltt_ust_event *trace_ust_find_event(struct lttng_ht *ht,
 170                 char *name, struct lttng_filter_bytecode *filter,
 171                 enum lttng_ust_loglevel_type loglevel_type, int loglevel_value,
 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_type = loglevel_type;
 184         key.loglevel_value = loglevel_value;
 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         DBG2("UST trace session create successful");
 286
 287         return lus;
 288
 289 error_consumer:
 290         ht_cleanup_push(lus->domain_global.channels);
 291         ht_cleanup_push(lus->agents);
 292         free(lus);
 293 error:
 294         return NULL;
 295 }
 296
 297 /*
 298  * Allocate and initialize a ust channel data structure.
 299  *
 300  * Return pointer to structure or NULL.
 301  */
 302 struct ltt_ust_channel *trace_ust_create_channel(struct lttng_channel *chan,
 303                 enum lttng_domain_type domain)
 304 {
 305         struct ltt_ust_channel *luc;
 306
 307         assert(chan);
 308
 309         luc = zmalloc(sizeof(struct ltt_ust_channel));
 310         if (luc == NULL) {
 311                 PERROR("ltt_ust_channel zmalloc");
 312                 goto error;
 313         }
 314
 315         luc->domain = domain;
 316
 317         /* Copy UST channel attributes */
 318         luc->attr.overwrite = chan->attr.overwrite;
 319         luc->attr.subbuf_size = chan->attr.subbuf_size;
 320         luc->attr.num_subbuf = chan->attr.num_subbuf;
 321         luc->attr.switch_timer_interval = chan->attr.switch_timer_interval;
 322         luc->attr.read_timer_interval = chan->attr.read_timer_interval;
 323         luc->attr.output = (enum lttng_ust_output) chan->attr.output;
 324
 325         /* Translate to UST output enum */
 326         switch (luc->attr.output) {
 327         default:
 328                 luc->attr.output = LTTNG_UST_MMAP;
 329                 break;
 330         }
 331
 332         /*
 333          * If we receive an empty string for channel name, it means the
 334          * default channel name is requested.
 335          */
 336         if (chan->name[0] == '\0') {
 337                 strncpy(luc->name, DEFAULT_CHANNEL_NAME, sizeof(luc->name));
 338         } else {
 339                 /* Copy channel name */
 340                 strncpy(luc->name, chan->name, sizeof(luc->name));
 341         }
 342         luc->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 343
 344         /* Init node */
 345         lttng_ht_node_init_str(&luc->node, luc->name);
 346         CDS_INIT_LIST_HEAD(&luc->ctx_list);
 347
 348         /* Alloc hash tables */
 349         luc->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 350         luc->ctx = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
 351
 352         /* On-disk circular buffer parameters */
 353         luc->tracefile_size = chan->attr.tracefile_size;
 354         luc->tracefile_count = chan->attr.tracefile_count;
 355
 356         DBG2("Trace UST channel %s created", luc->name);
 357
 358 error:
 359         return luc;
 360 }
 361
 362 /*
 363  * Allocate and initialize a ust event. Set name and event type.
 364  * We own filter_expression, filter, and exclusion.
 365  *
 366  * Return pointer to structure or NULL.
 367  */
 368 struct ltt_ust_event *trace_ust_create_event(struct lttng_event *ev,
 369                 char *filter_expression,
 370                 struct lttng_filter_bytecode *filter,
 371                 struct lttng_event_exclusion *exclusion,
 372                 bool internal_event)
 373 {
 374         struct ltt_ust_event *lue;
 375
 376         assert(ev);
 377
 378         lue = zmalloc(sizeof(struct ltt_ust_event));
 379         if (lue == NULL) {
 380                 PERROR("ust event zmalloc");
 381                 goto error;
 382         }
 383
 384         lue->internal = internal_event;
 385
 386         switch (ev->type) {
 387         case LTTNG_EVENT_PROBE:
 388                 lue->attr.instrumentation = LTTNG_UST_PROBE;
 389                 break;
 390         case LTTNG_EVENT_FUNCTION:
 391                 lue->attr.instrumentation = LTTNG_UST_FUNCTION;
 392                 break;
 393         case LTTNG_EVENT_FUNCTION_ENTRY:
 394                 lue->attr.instrumentation = LTTNG_UST_FUNCTION;
 395                 break;
 396         case LTTNG_EVENT_TRACEPOINT:
 397                 lue->attr.instrumentation = LTTNG_UST_TRACEPOINT;
 398                 break;
 399         default:
 400                 ERR("Unknown ust instrumentation type (%d)", ev->type);
 401                 goto error_free_event;
 402         }
 403
 404         /* Copy event name */
 405         strncpy(lue->attr.name, ev->name, LTTNG_UST_SYM_NAME_LEN);
 406         lue->attr.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 407
 408         switch (ev->loglevel_type) {
 409         case LTTNG_EVENT_LOGLEVEL_ALL:
 410                 lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_ALL;
 411                 lue->attr.loglevel = -1;        /* Force to -1 */
 412                 break;
 413         case LTTNG_EVENT_LOGLEVEL_RANGE:
 414                 lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_RANGE;
 415                 lue->attr.loglevel = ev->loglevel;
 416                 break;
 417         case LTTNG_EVENT_LOGLEVEL_SINGLE:
 418                 lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_SINGLE;
 419                 lue->attr.loglevel = ev->loglevel;
 420                 break;
 421         default:
 422                 ERR("Unknown ust loglevel type (%d)", ev->loglevel_type);
 423                 goto error_free_event;
 424         }
 425
 426         /* Same layout. */
 427         lue->filter_expression = filter_expression;
 428         lue->filter = filter;
 429         lue->exclusion = exclusion;
 430
 431         /* Init node */
 432         lttng_ht_node_init_str(&lue->node, lue->attr.name);
 433
 434         DBG2("Trace UST event %s, loglevel (%d,%d) created",
 435                 lue->attr.name, lue->attr.loglevel_type,
 436                 lue->attr.loglevel);
 437
 438         return lue;
 439
 440 error_free_event:
 441         free(lue);
 442 error:
 443         free(filter_expression);
 444         free(filter);
 445         free(exclusion);
 446         return NULL;
 447 }
 448
 449 static
 450 int trace_ust_context_type_event_to_ust(enum lttng_event_context_type type)
 451 {
 452         int utype;
 453
 454         switch (type) {
 455         case LTTNG_EVENT_CONTEXT_VTID:
 456                 utype = LTTNG_UST_CONTEXT_VTID;
 457                 break;
 458         case LTTNG_EVENT_CONTEXT_VPID:
 459                 utype = LTTNG_UST_CONTEXT_VPID;
 460                 break;
 461         case LTTNG_EVENT_CONTEXT_PTHREAD_ID:
 462                 utype = LTTNG_UST_CONTEXT_PTHREAD_ID;
 463                 break;
 464         case LTTNG_EVENT_CONTEXT_PROCNAME:
 465                 utype = LTTNG_UST_CONTEXT_PROCNAME;
 466                 break;
 467         case LTTNG_EVENT_CONTEXT_IP:
 468                 utype = LTTNG_UST_CONTEXT_IP;
 469                 break;
 470         case LTTNG_EVENT_CONTEXT_PERF_THREAD_COUNTER:
 471                 if (!ustctl_has_perf_counters()) {
 472                         utype = -1;
 473                         WARN("Perf counters not implemented in UST");
 474                 } else {
 475                         utype = LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER;
 476                 }
 477                 break;
 478         default:
 479                 ERR("Invalid UST context");
 480                 utype = -1;
 481                 break;
 482         }
 483         return utype;
 484 }
 485
 486 /*
 487  * Return 1 if contexts match, 0 otherwise.
 488  */
 489 int trace_ust_match_context(struct ltt_ust_context *uctx,
 490                 struct lttng_event_context *ctx)
 491 {
 492         int utype;
 493
 494         utype = trace_ust_context_type_event_to_ust(ctx->ctx);
 495         if (utype < 0) {
 496                 return 0;
 497         }
 498         if (uctx->ctx.ctx != utype) {
 499                 return 0;
 500         }
 501         switch (utype) {
 502         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
 503                 if (uctx->ctx.u.perf_counter.type
 504                                 != ctx->u.perf_counter.type) {
 505                         return 0;
 506                 }
 507                 if (uctx->ctx.u.perf_counter.config
 508                                 != ctx->u.perf_counter.config) {
 509                         return 0;
 510                 }
 511                 if (strncmp(uctx->ctx.u.perf_counter.name,
 512                                 ctx->u.perf_counter.name,
 513                                 LTTNG_UST_SYM_NAME_LEN)) {
 514                         return 0;
 515                 }
 516                 break;
 517         default:
 518                 break;
 519
 520         }
 521         return 1;
 522 }
 523
 524 /*
 525  * Allocate and initialize an UST context.
 526  *
 527  * Return pointer to structure or NULL.
 528  */
 529 struct ltt_ust_context *trace_ust_create_context(
 530                 struct lttng_event_context *ctx)
 531 {
 532         struct ltt_ust_context *uctx;
 533         int utype;
 534
 535         assert(ctx);
 536
 537         utype = trace_ust_context_type_event_to_ust(ctx->ctx);
 538         if (utype < 0) {
 539                 return NULL;
 540         }
 541
 542         uctx = zmalloc(sizeof(struct ltt_ust_context));
 543         if (uctx == NULL) {
 544                 PERROR("zmalloc ltt_ust_context");
 545                 goto error;
 546         }
 547
 548         uctx->ctx.ctx = (enum lttng_ust_context_type) utype;
 549         switch (utype) {
 550         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
 551                 uctx->ctx.u.perf_counter.type = ctx->u.perf_counter.type;
 552                 uctx->ctx.u.perf_counter.config = ctx->u.perf_counter.config;
 553                 strncpy(uctx->ctx.u.perf_counter.name, ctx->u.perf_counter.name,
 554                                 LTTNG_UST_SYM_NAME_LEN);
 555                 uctx->ctx.u.perf_counter.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 556                 break;
 557         default:
 558                 break;
 559         }
 560         lttng_ht_node_init_ulong(&uctx->node, (unsigned long) uctx->ctx.ctx);
 561
 562         return uctx;
 563
 564 error:
 565         return NULL;
 566 }
 567
 568 static
 569 void destroy_pid_tracker_node_rcu(struct rcu_head *head)
 570 {
 571         struct ust_pid_tracker_node *tracker_node =
 572                 caa_container_of(head, struct ust_pid_tracker_node, node.head);
 573         free(tracker_node);
 574 }
 575
 576 static
 577 void destroy_pid_tracker_node(struct ust_pid_tracker_node *tracker_node)
 578 {
 579
 580         call_rcu(&tracker_node->node.head, destroy_pid_tracker_node_rcu);
 581 }
 582
 583 static
 584 int init_pid_tracker(struct ust_pid_tracker *pid_tracker)
 585 {
 586         int ret = 0;
 587
 588         pid_tracker->ht = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
 589         if (!pid_tracker->ht) {
 590                 ret = -1;
 591                 goto end;
 592         }
 593
 594 end:
 595         return ret;
 596 }
 597
 598 /*
 599  * Teardown pid tracker content, but don't free pid_tracker object.
 600  */
 601 static
 602 void fini_pid_tracker(struct ust_pid_tracker *pid_tracker)
 603 {
 604         struct ust_pid_tracker_node *tracker_node;
 605         struct lttng_ht_iter iter;
 606
 607         if (!pid_tracker->ht) {
 608                 return;
 609         }
 610         rcu_read_lock();
 611         cds_lfht_for_each_entry(pid_tracker->ht->ht,
 612                         &iter.iter, tracker_node, node.node) {
 613                 int ret = lttng_ht_del(pid_tracker->ht, &iter);
 614
 615                 assert(!ret);
 616                 destroy_pid_tracker_node(tracker_node);
 617         }
 618         rcu_read_unlock();
 619         ht_cleanup_push(pid_tracker->ht);
 620         pid_tracker->ht = NULL;
 621 }
 622
 623 static
 624 struct ust_pid_tracker_node *pid_tracker_lookup(
 625                 struct ust_pid_tracker *pid_tracker, int pid,
 626                 struct lttng_ht_iter *iter)
 627 {
 628         unsigned long _pid = (unsigned long) pid;
 629         struct lttng_ht_node_ulong *node;
 630
 631         lttng_ht_lookup(pid_tracker->ht, (void *) _pid, iter);
 632         node = lttng_ht_iter_get_node_ulong(iter);
 633         if (node) {
 634                 return caa_container_of(node, struct ust_pid_tracker_node,
 635                         node);
 636         } else {
 637                 return NULL;
 638         }
 639 }
 640
 641 static
 642 int pid_tracker_add_pid(struct ust_pid_tracker *pid_tracker, int pid)
 643 {
 644         int retval = LTTNG_OK;
 645         struct ust_pid_tracker_node *tracker_node;
 646         struct lttng_ht_iter iter;
 647
 648         if (pid < 0) {
 649                 retval = LTTNG_ERR_INVALID;
 650                 goto end;
 651         }
 652         tracker_node = pid_tracker_lookup(pid_tracker, pid, &iter);
 653         if (tracker_node) {
 654                 /* Already exists. */
 655                 retval = LTTNG_ERR_PID_TRACKED;
 656                 goto end;
 657         }
 658         tracker_node = zmalloc(sizeof(*tracker_node));
 659         if (!tracker_node) {
 660                 retval = LTTNG_ERR_NOMEM;
 661                 goto end;
 662         }
 663         lttng_ht_node_init_ulong(&tracker_node->node, (unsigned long) pid);
 664         lttng_ht_add_unique_ulong(pid_tracker->ht, &tracker_node->node);
 665 end:
 666         return retval;
 667 }
 668
 669 static
 670 int pid_tracker_del_pid(struct ust_pid_tracker *pid_tracker, int pid)
 671 {
 672         int retval = LTTNG_OK, ret;
 673         struct ust_pid_tracker_node *tracker_node;
 674         struct lttng_ht_iter iter;
 675
 676         if (pid < 0) {
 677                 retval = LTTNG_ERR_INVALID;
 678                 goto end;
 679         }
 680         tracker_node = pid_tracker_lookup(pid_tracker, pid, &iter);
 681         if (!tracker_node) {
 682                 /* Not found */
 683                 retval = LTTNG_ERR_PID_NOT_TRACKED;
 684                 goto end;
 685         }
 686         ret = lttng_ht_del(pid_tracker->ht, &iter);
 687         assert(!ret);
 688
 689         destroy_pid_tracker_node(tracker_node);
 690 end:
 691         return retval;
 692 }
 693
 694 /*
 695  * The session lock is held when calling this function.
 696  */
 697 int trace_ust_pid_tracker_lookup(struct ltt_ust_session *session, int pid)
 698 {
 699         struct lttng_ht_iter iter;
 700
 701         if (!session->pid_tracker.ht) {
 702                 return 1;
 703         }
 704         if (pid_tracker_lookup(&session->pid_tracker, pid, &iter)) {
 705                 return 1;
 706         }
 707         return 0;
 708 }
 709
 710 /*
 711  * Called with the session lock held.
 712  */
 713 int trace_ust_track_pid(struct ltt_ust_session *session, int pid)
 714 {
 715         int retval = LTTNG_OK;
 716
 717         if (pid == -1) {
 718                 /* Track all pids: destroy tracker if exists. */
 719                 if (session->pid_tracker.ht) {
 720                         fini_pid_tracker(&session->pid_tracker);
 721                         /* Ensure all apps have session. */
 722                         ust_app_global_update_all(session);
 723                 }
 724         } else {
 725                 int ret;
 726
 727                 if (!session->pid_tracker.ht) {
 728                         /* Create tracker. */
 729                         if (init_pid_tracker(&session->pid_tracker)) {
 730                                 ERR("Error initializing PID tracker");
 731                                 retval = LTTNG_ERR_NOMEM;
 732                                 goto end;
 733                         }
 734                         ret = pid_tracker_add_pid(&session->pid_tracker, pid);
 735                         if (ret != LTTNG_OK) {
 736                                 retval = ret;
 737                                 fini_pid_tracker(&session->pid_tracker);
 738                                 goto end;
 739                         }
 740                         /* Remove all apps from session except pid. */
 741                         ust_app_global_update_all(session);
 742                 } else {
 743                         struct ust_app *app;
 744
 745                         ret = pid_tracker_add_pid(&session->pid_tracker, pid);
 746                         if (ret != LTTNG_OK) {
 747                                 retval = ret;
 748                                 goto end;
 749                         }
 750                         /* Add session to application */
 751                         app = ust_app_find_by_pid(pid);
 752                         if (app) {
 753                                 ust_app_global_update(session, app);
 754                         }
 755                 }
 756         }
 757 end:
 758         return retval;
 759 }
 760
 761 /*
 762  * Called with the session lock held.
 763  */
 764 int trace_ust_untrack_pid(struct ltt_ust_session *session, int pid)
 765 {
 766         int retval = LTTNG_OK;
 767
 768         if (pid == -1) {
 769                 /* Create empty tracker, replace old tracker. */
 770                 struct ust_pid_tracker tmp_tracker;
 771
 772                 tmp_tracker = session->pid_tracker;
 773                 if (init_pid_tracker(&session->pid_tracker)) {
 774                         ERR("Error initializing PID tracker");
 775                         retval = LTTNG_ERR_NOMEM;
 776                         /* Rollback operation. */
 777                         session->pid_tracker = tmp_tracker;
 778                         goto end;
 779                 }
 780                 fini_pid_tracker(&tmp_tracker);
 781
 782                 /* Remove session from all applications */
 783                 ust_app_global_update_all(session);
 784         } else {
 785                 int ret;
 786                 struct ust_app *app;
 787
 788                 if (!session->pid_tracker.ht) {
 789                         /* No PID being tracked. */
 790                         retval = LTTNG_ERR_PID_NOT_TRACKED;
 791                         goto end;
 792                 }
 793                 /* Remove PID from tracker */
 794                 ret = pid_tracker_del_pid(&session->pid_tracker, pid);
 795                 if (ret != LTTNG_OK) {
 796                         retval = ret;
 797                         goto end;
 798                 }
 799                 /* Remove session from application. */
 800                 app = ust_app_find_by_pid(pid);
 801                 if (app) {
 802                         ust_app_global_update(session, app);
 803                 }
 804         }
 805 end:
 806         return retval;
 807 }
 808
 809 /*
 810  * Called with session lock held.
 811  */
 812 ssize_t trace_ust_list_tracker_pids(struct ltt_ust_session *session,
 813                 int32_t **_pids)
 814 {
 815         struct ust_pid_tracker_node *tracker_node;
 816         struct lttng_ht_iter iter;
 817         unsigned long count, i = 0;
 818         long approx[2];
 819         int32_t *pids;
 820         int ret = 0;
 821
 822         if (!session->pid_tracker.ht) {
 823                 /* Tracker disabled. Set first entry to -1. */
 824                 pids = zmalloc(sizeof(*pids));
 825                 if (!pids) {
 826                         ret = -1;
 827                         goto end;
 828                 }
 829                 pids[0] = -1;
 830                 *_pids = pids;
 831                 return 1;
 832         }
 833
 834         rcu_read_lock();
 835         cds_lfht_count_nodes(session->pid_tracker.ht->ht,
 836                 &approx[0], &count, &approx[1]);
 837         pids = zmalloc(sizeof(*pids) * count);
 838         if (!pids) {
 839                 ret = -1;
 840                 goto end;
 841         }
 842         cds_lfht_for_each_entry(session->pid_tracker.ht->ht,
 843                         &iter.iter, tracker_node, node.node) {
 844                 pids[i++] = tracker_node->node.key;
 845         }
 846         *_pids = pids;
 847         ret = count;
 848 end:
 849         rcu_read_unlock();
 850         return ret;
 851 }
 852
 853 /*
 854  * RCU safe free context structure.
 855  */
 856 static void destroy_context_rcu(struct rcu_head *head)
 857 {
 858         struct lttng_ht_node_ulong *node =
 859                 caa_container_of(head, struct lttng_ht_node_ulong, head);
 860         struct ltt_ust_context *ctx =
 861                 caa_container_of(node, struct ltt_ust_context, node);
 862
 863         free(ctx);
 864 }
 865
 866 /*
 867  * Cleanup UST context hash table.
 868  */
 869 static void destroy_contexts(struct lttng_ht *ht)
 870 {
 871         int ret;
 872         struct lttng_ht_node_ulong *node;
 873         struct lttng_ht_iter iter;
 874         struct ltt_ust_context *ctx;
 875
 876         assert(ht);
 877
 878         rcu_read_lock();
 879         cds_lfht_for_each_entry(ht->ht, &iter.iter, node, node) {
 880                 /* Remove from ordered list. */
 881                 ctx = caa_container_of(node, struct ltt_ust_context, node);
 882                 cds_list_del(&ctx->list);
 883                 /* Remove from channel's hash table. */
 884                 ret = lttng_ht_del(ht, &iter);
 885                 if (!ret) {
 886                         call_rcu(&node->head, destroy_context_rcu);
 887                 }
 888         }
 889         rcu_read_unlock();
 890
 891         ht_cleanup_push(ht);
 892 }
 893
 894 /*
 895  * Cleanup ust event structure.
 896  */
 897 void trace_ust_destroy_event(struct ltt_ust_event *event)
 898 {
 899         assert(event);
 900
 901         DBG2("Trace destroy UST event %s", event->attr.name);
 902         free(event->filter_expression);
 903         free(event->filter);
 904         free(event->exclusion);
 905         free(event);
 906 }
 907
 908 /*
 909  * URCU intermediate call to complete destroy event.
 910  */
 911 static void destroy_event_rcu(struct rcu_head *head)
 912 {
 913         struct lttng_ht_node_str *node =
 914                 caa_container_of(head, struct lttng_ht_node_str, head);
 915         struct ltt_ust_event *event =
 916                 caa_container_of(node, struct ltt_ust_event, node);
 917
 918         trace_ust_destroy_event(event);
 919 }
 920
 921 /*
 922  * Cleanup UST events hashtable.
 923  */
 924 static void destroy_events(struct lttng_ht *events)
 925 {
 926         int ret;
 927         struct lttng_ht_node_str *node;
 928         struct lttng_ht_iter iter;
 929
 930         assert(events);
 931
 932         rcu_read_lock();
 933         cds_lfht_for_each_entry(events->ht, &iter.iter, node, node) {
 934                 ret = lttng_ht_del(events, &iter);
 935                 assert(!ret);
 936                 call_rcu(&node->head, destroy_event_rcu);
 937         }
 938         rcu_read_unlock();
 939
 940         ht_cleanup_push(events);
 941 }
 942
 943 /*
 944  * Cleanup ust channel structure.
 945  *
 946  * Should _NOT_ be called with RCU read lock held.
 947  */
 948 static void _trace_ust_destroy_channel(struct ltt_ust_channel *channel)
 949 {
 950         assert(channel);
 951
 952         DBG2("Trace destroy UST channel %s", channel->name);
 953
 954         free(channel);
 955 }
 956
 957 /*
 958  * URCU intermediate call to complete destroy channel.
 959  */
 960 static void destroy_channel_rcu(struct rcu_head *head)
 961 {
 962         struct lttng_ht_node_str *node =
 963                 caa_container_of(head, struct lttng_ht_node_str, head);
 964         struct ltt_ust_channel *channel =
 965                 caa_container_of(node, struct ltt_ust_channel, node);
 966
 967         _trace_ust_destroy_channel(channel);
 968 }
 969
 970 void trace_ust_destroy_channel(struct ltt_ust_channel *channel)
 971 {
 972         /* Destroying all events of the channel */
 973         destroy_events(channel->events);
 974         /* Destroying all context of the channel */
 975         destroy_contexts(channel->ctx);
 976
 977         call_rcu(&channel->node.head, destroy_channel_rcu);
 978 }
 979
 980 /*
 981  * Remove an UST channel from a channel HT.
 982  */
 983 void trace_ust_delete_channel(struct lttng_ht *ht,
 984                 struct ltt_ust_channel *channel)
 985 {
 986         int ret;
 987         struct lttng_ht_iter iter;
 988
 989         assert(ht);
 990         assert(channel);
 991
 992         iter.iter.node = &channel->node.node;
 993         ret = lttng_ht_del(ht, &iter);
 994         assert(!ret);
 995 }
 996
 997 /*
 998  * Iterate over a hash table containing channels and cleanup safely.
 999  */
1000 static void destroy_channels(struct lttng_ht *channels)
1001 {
1002         struct lttng_ht_node_str *node;
1003         struct lttng_ht_iter iter;
1004
1005         assert(channels);
1006
1007         rcu_read_lock();
1008         cds_lfht_for_each_entry(channels->ht, &iter.iter, node, node) {
1009                 struct ltt_ust_channel *chan =
1010                         caa_container_of(node, struct ltt_ust_channel, node);
1011
1012                 trace_ust_delete_channel(channels, chan);
1013                 trace_ust_destroy_channel(chan);
1014         }
1015         rcu_read_unlock();
1016
1017         ht_cleanup_push(channels);
1018 }
1019
1020 /*
1021  * Cleanup UST global domain.
1022  */
1023 static void destroy_domain_global(struct ltt_ust_domain_global *dom)
1024 {
1025         assert(dom);
1026
1027         destroy_channels(dom->channels);
1028 }
1029
1030 /*
1031  * Cleanup ust session structure
1032  *
1033  * Should *NOT* be called with RCU read-side lock held.
1034  */
1035 void trace_ust_destroy_session(struct ltt_ust_session *session)
1036 {
1037         struct agent *agt;
1038         struct buffer_reg_uid *reg, *sreg;
1039         struct lttng_ht_iter iter;
1040
1041         assert(session);
1042
1043         DBG2("Trace UST destroy session %" PRIu64, session->id);
1044
1045         /* Cleaning up UST domain */
1046         destroy_domain_global(&session->domain_global);
1047
1048         rcu_read_lock();
1049         cds_lfht_for_each_entry(session->agents->ht, &iter.iter, agt, node.node) {
1050                 int ret = lttng_ht_del(session->agents, &iter);
1051
1052                 assert(!ret);
1053                 agent_destroy(agt);
1054         }
1055         rcu_read_unlock();
1056
1057         ht_cleanup_push(session->agents);
1058
1059         /* Cleanup UID buffer registry object(s). */
1060         cds_list_for_each_entry_safe(reg, sreg, &session->buffer_reg_uid_list,
1061                         lnode) {
1062                 cds_list_del(&reg->lnode);
1063                 buffer_reg_uid_remove(reg);
1064                 buffer_reg_uid_destroy(reg, session->consumer);
1065         }
1066
1067         consumer_output_put(session->consumer);
1068
1069         fini_pid_tracker(&session->pid_tracker);
1070
1071         free(session);
1072 }