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
  74         assert(node);
  75         assert(_key);
  76
  77         event = caa_container_of(node, struct ltt_ust_event, node.node);
  78         key = _key;
  79
  80         /* Match the 4 elements of the key: name, filter, loglevel, exclusions. */
  81
  82         /* Event name */
  83         if (strncmp(event->attr.name, key->name, sizeof(event->attr.name)) != 0) {
  84                 goto no_match;
  85         }
  86
  87         /* Event loglevel. */
  88         if (event->attr.loglevel != key->loglevel) {
  89                 if (event->attr.loglevel_type == LTTNG_UST_LOGLEVEL_ALL
  90                                 && key->loglevel == 0 && event->attr.loglevel == -1) {
  91                         /*
  92                          * Match is accepted. This is because on event creation, the
  93                          * loglevel is set to -1 if the event loglevel type is ALL so 0 and
  94                          * -1 are accepted for this loglevel type since 0 is the one set by
  95                          * the API when receiving an enable event.
  96                          */
  97                 } else {
  98                         goto no_match;
  99                 }
 100         }
 101
 102         /* Only one of the filters is NULL, fail. */
 103         if ((key->filter && !event->filter) || (!key->filter && event->filter)) {
 104                 goto no_match;
 105         }
 106
 107         if (key->filter && event->filter) {
 108                 /* Both filters exists, check length followed by the bytecode. */
 109                 if (event->filter->len != key->filter->len ||
 110                                 memcmp(event->filter->data, key->filter->data,
 111                                         event->filter->len) != 0) {
 112                         goto no_match;
 113                 }
 114         }
 115
 116         /* If only one of the exclusions is NULL, fail. */
 117         if ((key->exclusion && !event->exclusion) || (!key->exclusion && event->exclusion)) {
 118                 goto no_match;
 119         }
 120
 121         if (key->exclusion && event->exclusion) {
 122                 /* Both exclusions exist; check count followed by names. */
 123                 if (event->exclusion->count != key->exclusion->count ||
 124                                 memcmp(event->exclusion->names, key->exclusion->names,
 125                                         event->exclusion->count * LTTNG_SYMBOL_NAME_LEN) != 0) {
 126                         goto no_match;
 127                 }
 128         }
 129         /* Match. */
 130         return 1;
 131
 132 no_match:
 133         return 0;
 134 }
 135
 136 /*
 137  * Find the channel in the hashtable and return channel pointer. RCU read side
 138  * lock MUST be acquired before calling this.
 139  */
 140 struct ltt_ust_channel *trace_ust_find_channel_by_name(struct lttng_ht *ht,
 141                 char *name)
 142 {
 143         struct lttng_ht_node_str *node;
 144         struct lttng_ht_iter iter;
 145
 146         /*
 147          * If we receive an empty string for channel name, it means the
 148          * default channel name is requested.
 149          */
 150         if (name[0] == '\0')
 151                 name = DEFAULT_CHANNEL_NAME;
 152
 153         lttng_ht_lookup(ht, (void *)name, &iter);
 154         node = lttng_ht_iter_get_node_str(&iter);
 155         if (node == NULL) {
 156                 goto error;
 157         }
 158
 159         DBG2("Trace UST channel %s found by name", name);
 160
 161         return caa_container_of(node, struct ltt_ust_channel, node);
 162
 163 error:
 164         DBG2("Trace UST channel %s not found by name", name);
 165         return NULL;
 166 }
 167
 168 /*
 169  * Find the event in the hashtable and return event pointer. RCU read side lock
 170  * MUST be acquired before calling this.
 171  */
 172 struct ltt_ust_event *trace_ust_find_event(struct lttng_ht *ht,
 173                 char *name, struct lttng_filter_bytecode *filter, int loglevel,
 174                 struct lttng_event_exclusion *exclusion)
 175 {
 176         struct lttng_ht_node_str *node;
 177         struct lttng_ht_iter iter;
 178         struct ltt_ust_ht_key key;
 179
 180         assert(name);
 181         assert(ht);
 182
 183         key.name = name;
 184         key.filter = filter;
 185         key.loglevel = loglevel;
 186         key.exclusion = exclusion;
 187
 188         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 189                         trace_ust_ht_match_event, &key, &iter.iter);
 190         node = lttng_ht_iter_get_node_str(&iter);
 191         if (node == NULL) {
 192                 goto error;
 193         }
 194
 195         DBG2("Trace UST event %s found", key.name);
 196
 197         return caa_container_of(node, struct ltt_ust_event, node);
 198
 199 error:
 200         DBG2("Trace UST event %s NOT found", key.name);
 201         return NULL;
 202 }
 203
 204 /*
 205  * Lookup an agent in the session agents hash table by domain type and return
 206  * the object if found else NULL.
 207  *
 208  * RCU read side lock must be acquired before calling and only released
 209  * once the agent is no longer in scope or being used.
 210  */
 211 struct agent *trace_ust_find_agent(struct ltt_ust_session *session,
 212                 enum lttng_domain_type domain_type)
 213 {
 214         struct agent *agt = NULL;
 215         struct lttng_ht_node_u64 *node;
 216         struct lttng_ht_iter iter;
 217         uint64_t key;
 218
 219         assert(session);
 220
 221         DBG3("Trace ust agent lookup for domain %d", domain_type);
 222
 223         key = domain_type;
 224
 225         lttng_ht_lookup(session->agents, &key, &iter);
 226         node = lttng_ht_iter_get_node_u64(&iter);
 227         if (!node) {
 228                 goto end;
 229         }
 230         agt = caa_container_of(node, struct agent, node);
 231
 232 end:
 233         return agt;
 234 }
 235
 236 /*
 237  * Allocate and initialize a ust session data structure.
 238  *
 239  * Return pointer to structure or NULL.
 240  */
 241 struct ltt_ust_session *trace_ust_create_session(uint64_t session_id)
 242 {
 243         struct ltt_ust_session *lus;
 244
 245         /* Allocate a new ltt ust session */
 246         lus = zmalloc(sizeof(struct ltt_ust_session));
 247         if (lus == NULL) {
 248                 PERROR("create ust session zmalloc");
 249                 goto error;
 250         }
 251
 252         /* Init data structure */
 253         lus->id = session_id;
 254         lus->active = 0;
 255
 256         /* Set default metadata channel attribute. */
 257         lus->metadata_attr.overwrite = DEFAULT_CHANNEL_OVERWRITE;
 258         lus->metadata_attr.subbuf_size = default_get_metadata_subbuf_size();
 259         lus->metadata_attr.num_subbuf = DEFAULT_METADATA_SUBBUF_NUM;
 260         lus->metadata_attr.switch_timer_interval = DEFAULT_METADATA_SWITCH_TIMER;
 261         lus->metadata_attr.read_timer_interval = DEFAULT_METADATA_READ_TIMER;
 262         lus->metadata_attr.output = LTTNG_UST_MMAP;
 263
 264         /*
 265          * Default buffer type. This can be changed through an enable channel
 266          * requesting a different type. Note that this can only be changed once
 267          * during the session lifetime which is at the first enable channel and
 268          * only before start. The flag buffer_type_changed indicates the status.
 269          */
 270         lus->buffer_type = LTTNG_BUFFER_PER_UID;
 271         /* Once set to 1, the buffer_type is immutable for the session. */
 272         lus->buffer_type_changed = 0;
 273         /* Init it in case it get used after allocation. */
 274         CDS_INIT_LIST_HEAD(&lus->buffer_reg_uid_list);
 275
 276         /* Alloc UST global domain channels' HT */
 277         lus->domain_global.channels = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 278         /* Alloc agent hash table. */
 279         lus->agents = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
 280
 281         lus->consumer = consumer_create_output(CONSUMER_DST_LOCAL);
 282         if (lus->consumer == NULL) {
 283                 goto error_consumer;
 284         }
 285
 286         /*
 287          * The tmp_consumer stays NULL until a set_consumer_uri command is
 288          * executed. At this point, the consumer should be nullify until an
 289          * enable_consumer command. This assignment is symbolic since we've zmalloc
 290          * the struct.
 291          */
 292         lus->tmp_consumer = NULL;
 293
 294         DBG2("UST trace session create successful");
 295
 296         return lus;
 297
 298 error_consumer:
 299         ht_cleanup_push(lus->domain_global.channels);
 300         ht_cleanup_push(lus->agents);
 301         free(lus);
 302 error:
 303         return NULL;
 304 }
 305
 306 /*
 307  * Allocate and initialize a ust channel data structure.
 308  *
 309  * Return pointer to structure or NULL.
 310  */
 311 struct ltt_ust_channel *trace_ust_create_channel(struct lttng_channel *chan)
 312 {
 313         struct ltt_ust_channel *luc;
 314
 315         assert(chan);
 316
 317         luc = zmalloc(sizeof(struct ltt_ust_channel));
 318         if (luc == NULL) {
 319                 PERROR("ltt_ust_channel zmalloc");
 320                 goto error;
 321         }
 322
 323         /* Copy UST channel attributes */
 324         luc->attr.overwrite = chan->attr.overwrite;
 325         luc->attr.subbuf_size = chan->attr.subbuf_size;
 326         luc->attr.num_subbuf = chan->attr.num_subbuf;
 327         luc->attr.switch_timer_interval = chan->attr.switch_timer_interval;
 328         luc->attr.read_timer_interval = chan->attr.read_timer_interval;
 329         luc->attr.output = (enum lttng_ust_output) chan->attr.output;
 330
 331         /* Translate to UST output enum */
 332         switch (luc->attr.output) {
 333         default:
 334                 luc->attr.output = LTTNG_UST_MMAP;
 335                 break;
 336         }
 337
 338         /*
 339          * If we receive an empty string for channel name, it means the
 340          * default channel name is requested.
 341          */
 342         if (chan->name[0] == '\0') {
 343                 strncpy(luc->name, DEFAULT_CHANNEL_NAME, sizeof(luc->name));
 344         } else {
 345                 /* Copy channel name */
 346                 strncpy(luc->name, chan->name, sizeof(luc->name));
 347         }
 348         luc->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 349
 350         /* Init node */
 351         lttng_ht_node_init_str(&luc->node, luc->name);
 352         CDS_INIT_LIST_HEAD(&luc->ctx_list);
 353
 354         /* Alloc hash tables */
 355         luc->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 356         luc->ctx = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
 357
 358         /* On-disk circular buffer parameters */
 359         luc->tracefile_size = chan->attr.tracefile_size;
 360         luc->tracefile_count = chan->attr.tracefile_count;
 361
 362         DBG2("Trace UST channel %s created", luc->name);
 363
 364 error:
 365         return luc;
 366 }
 367
 368 /*
 369  * Allocate and initialize a ust event. Set name and event type.
 370  * We own filter_expression, filter, and exclusion.
 371  *
 372  * Return pointer to structure or NULL.
 373  */
 374 struct ltt_ust_event *trace_ust_create_event(struct lttng_event *ev,
 375                 char *filter_expression,
 376                 struct lttng_filter_bytecode *filter,
 377                 struct lttng_event_exclusion *exclusion)
 378 {
 379         struct ltt_ust_event *lue;
 380
 381         assert(ev);
 382
 383         lue = zmalloc(sizeof(struct ltt_ust_event));
 384         if (lue == NULL) {
 385                 PERROR("ust event zmalloc");
 386                 goto error;
 387         }
 388
 389         switch (ev->type) {
 390         case LTTNG_EVENT_PROBE:
 391                 lue->attr.instrumentation = LTTNG_UST_PROBE;
 392                 break;
 393         case LTTNG_EVENT_FUNCTION:
 394                 lue->attr.instrumentation = LTTNG_UST_FUNCTION;
 395                 break;
 396         case LTTNG_EVENT_FUNCTION_ENTRY:
 397                 lue->attr.instrumentation = LTTNG_UST_FUNCTION;
 398                 break;
 399         case LTTNG_EVENT_TRACEPOINT:
 400                 lue->attr.instrumentation = LTTNG_UST_TRACEPOINT;
 401                 break;
 402         default:
 403                 ERR("Unknown ust instrumentation type (%d)", ev->type);
 404                 goto error_free_event;
 405         }
 406
 407         /* Copy event name */
 408         strncpy(lue->attr.name, ev->name, LTTNG_UST_SYM_NAME_LEN);
 409         lue->attr.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 410
 411         switch (ev->loglevel_type) {
 412         case LTTNG_EVENT_LOGLEVEL_ALL:
 413                 lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_ALL;
 414                 lue->attr.loglevel = -1;        /* Force to -1 */
 415                 break;
 416         case LTTNG_EVENT_LOGLEVEL_RANGE:
 417                 lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_RANGE;
 418                 lue->attr.loglevel = ev->loglevel;
 419                 break;
 420         case LTTNG_EVENT_LOGLEVEL_SINGLE:
 421                 lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_SINGLE;
 422                 lue->attr.loglevel = ev->loglevel;
 423                 break;
 424         default:
 425                 ERR("Unknown ust loglevel type (%d)", ev->loglevel_type);
 426                 goto error_free_event;
 427         }
 428
 429         /* Same layout. */
 430         lue->filter_expression = filter_expression;
 431         lue->filter = (struct lttng_ust_filter_bytecode *) filter;
 432         lue->exclusion = (struct lttng_event_exclusion *) exclusion;
 433
 434         /* Init node */
 435         lttng_ht_node_init_str(&lue->node, lue->attr.name);
 436
 437         DBG2("Trace UST event %s, loglevel (%d,%d) created",
 438                 lue->attr.name, lue->attr.loglevel_type,
 439                 lue->attr.loglevel);
 440
 441         return lue;
 442
 443 error_free_event:
 444         free(lue);
 445 error:
 446         free(filter_expression);
 447         free(filter);
 448         free(exclusion);
 449         return NULL;
 450 }
 451
 452 static
 453 int trace_ust_context_type_event_to_ust(enum lttng_event_context_type type)
 454 {
 455         int utype;
 456
 457         switch (type) {
 458         case LTTNG_EVENT_CONTEXT_VTID:
 459                 utype = LTTNG_UST_CONTEXT_VTID;
 460                 break;
 461         case LTTNG_EVENT_CONTEXT_VPID:
 462                 utype = LTTNG_UST_CONTEXT_VPID;
 463                 break;
 464         case LTTNG_EVENT_CONTEXT_PTHREAD_ID:
 465                 utype = LTTNG_UST_CONTEXT_PTHREAD_ID;
 466                 break;
 467         case LTTNG_EVENT_CONTEXT_PROCNAME:
 468                 utype = LTTNG_UST_CONTEXT_PROCNAME;
 469                 break;
 470         case LTTNG_EVENT_CONTEXT_IP:
 471                 utype = LTTNG_UST_CONTEXT_IP;
 472                 break;
 473         case LTTNG_EVENT_CONTEXT_PERF_THREAD_COUNTER:
 474                 if (!ustctl_has_perf_counters()) {
 475                         utype = -1;
 476                         WARN("Perf counters not implemented in UST");
 477                 } else {
 478                         utype = LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER;
 479                 }
 480                 break;
 481         default:
 482                 ERR("Invalid UST context");
 483                 utype = -1;
 484                 break;
 485         }
 486         return utype;
 487 }
 488
 489 /*
 490  * Return 1 if contexts match, 0 otherwise.
 491  */
 492 int trace_ust_match_context(struct ltt_ust_context *uctx,
 493                 struct lttng_event_context *ctx)
 494 {
 495         int utype;
 496
 497         utype = trace_ust_context_type_event_to_ust(ctx->ctx);
 498         if (utype < 0) {
 499                 return 0;
 500         }
 501         if (uctx->ctx.ctx != utype) {
 502                 return 0;
 503         }
 504         switch (utype) {
 505         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
 506                 if (uctx->ctx.u.perf_counter.type
 507                                 != ctx->u.perf_counter.type) {
 508                         return 0;
 509                 }
 510                 if (uctx->ctx.u.perf_counter.config
 511                                 != ctx->u.perf_counter.config) {
 512                         return 0;
 513                 }
 514                 if (strncmp(uctx->ctx.u.perf_counter.name,
 515                                 ctx->u.perf_counter.name,
 516                                 LTTNG_UST_SYM_NAME_LEN)) {
 517                         return 0;
 518                 }
 519                 break;
 520         default:
 521                 break;
 522
 523         }
 524         return 1;
 525 }
 526
 527 /*
 528  * Allocate and initialize an UST context.
 529  *
 530  * Return pointer to structure or NULL.
 531  */
 532 struct ltt_ust_context *trace_ust_create_context(
 533                 struct lttng_event_context *ctx)
 534 {
 535         struct ltt_ust_context *uctx;
 536         int utype;
 537
 538         assert(ctx);
 539
 540         utype = trace_ust_context_type_event_to_ust(ctx->ctx);
 541         if (utype < 0) {
 542                 return NULL;
 543         }
 544
 545         uctx = zmalloc(sizeof(struct ltt_ust_context));
 546         if (uctx == NULL) {
 547                 PERROR("zmalloc ltt_ust_context");
 548                 goto error;
 549         }
 550
 551         uctx->ctx.ctx = (enum lttng_ust_context_type) utype;
 552         switch (utype) {
 553         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
 554                 uctx->ctx.u.perf_counter.type = ctx->u.perf_counter.type;
 555                 uctx->ctx.u.perf_counter.config = ctx->u.perf_counter.config;
 556                 strncpy(uctx->ctx.u.perf_counter.name, ctx->u.perf_counter.name,
 557                                 LTTNG_UST_SYM_NAME_LEN);
 558                 uctx->ctx.u.perf_counter.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 559                 break;
 560         default:
 561                 break;
 562         }
 563         lttng_ht_node_init_ulong(&uctx->node, (unsigned long) uctx->ctx.ctx);
 564
 565         return uctx;
 566
 567 error:
 568         return NULL;
 569 }
 570
 571 static
 572 void destroy_pid_tracker_node_rcu(struct rcu_head *head)
 573 {
 574         struct ust_pid_tracker_node *tracker_node =
 575                 caa_container_of(head, struct ust_pid_tracker_node, node.head);
 576         free(tracker_node);
 577 }
 578
 579 static
 580 void destroy_pid_tracker_node(struct ust_pid_tracker_node *tracker_node)
 581 {
 582
 583         call_rcu(&tracker_node->node.head, destroy_pid_tracker_node_rcu);
 584 }
 585
 586 static
 587 int init_pid_tracker(struct ust_pid_tracker *pid_tracker)
 588 {
 589         int ret = 0;
 590
 591         pid_tracker->ht = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
 592         if (!pid_tracker->ht) {
 593                 ret = -1;
 594                 goto end;
 595         }
 596
 597 end:
 598         return ret;
 599 }
 600
 601 /*
 602  * Teardown pid tracker content, but don't free pid_tracker object.
 603  */
 604 static
 605 void fini_pid_tracker(struct ust_pid_tracker *pid_tracker)
 606 {
 607         struct ust_pid_tracker_node *tracker_node;
 608         struct lttng_ht_iter iter;
 609
 610         if (!pid_tracker->ht) {
 611                 return;
 612         }
 613         rcu_read_lock();
 614         cds_lfht_for_each_entry(pid_tracker->ht->ht,
 615                         &iter.iter, tracker_node, node.node) {
 616                 int ret = lttng_ht_del(pid_tracker->ht, &iter);
 617
 618                 assert(!ret);
 619                 destroy_pid_tracker_node(tracker_node);
 620         }
 621         rcu_read_unlock();
 622         ht_cleanup_push(pid_tracker->ht);
 623         pid_tracker->ht = NULL;
 624 }
 625
 626 static
 627 struct ust_pid_tracker_node *pid_tracker_lookup(
 628                 struct ust_pid_tracker *pid_tracker, int pid,
 629                 struct lttng_ht_iter *iter)
 630 {
 631         unsigned long _pid = (unsigned long) pid;
 632         struct lttng_ht_node_ulong *node;
 633
 634         lttng_ht_lookup(pid_tracker->ht, (void *) _pid, iter);
 635         node = lttng_ht_iter_get_node_ulong(iter);
 636         if (node) {
 637                 return caa_container_of(node, struct ust_pid_tracker_node,
 638                         node);
 639         } else {
 640                 return NULL;
 641         }
 642 }
 643
 644 static
 645 int pid_tracker_add_pid(struct ust_pid_tracker *pid_tracker, int pid)
 646 {
 647         int retval = LTTNG_OK;
 648         struct ust_pid_tracker_node *tracker_node;
 649         struct lttng_ht_iter iter;
 650
 651         if (pid < 0) {
 652                 retval = LTTNG_ERR_INVALID;
 653                 goto end;
 654         }
 655         tracker_node = pid_tracker_lookup(pid_tracker, pid, &iter);
 656         if (tracker_node) {
 657                 /* Already exists. */
 658                 retval = LTTNG_ERR_INVALID;
 659                 goto end;
 660         }
 661         tracker_node = zmalloc(sizeof(*tracker_node));
 662         if (!tracker_node) {
 663                 retval = LTTNG_ERR_NOMEM;
 664                 goto end;
 665         }
 666         lttng_ht_node_init_ulong(&tracker_node->node, (unsigned long) pid);
 667         lttng_ht_add_unique_ulong(pid_tracker->ht, &tracker_node->node);
 668 end:
 669         return retval;
 670 }
 671
 672 static
 673 int pid_tracker_del_pid(struct ust_pid_tracker *pid_tracker, int pid)
 674 {
 675         int retval = LTTNG_OK, ret;
 676         struct ust_pid_tracker_node *tracker_node;
 677         struct lttng_ht_iter iter;
 678
 679         if (pid < 0) {
 680                 retval = LTTNG_ERR_INVALID;
 681                 goto end;
 682         }
 683         tracker_node = pid_tracker_lookup(pid_tracker, pid, &iter);
 684         if (!tracker_node) {
 685                 /* Not found */
 686                 retval = LTTNG_ERR_INVALID;
 687                 goto end;
 688         }
 689         ret = lttng_ht_del(pid_tracker->ht, &iter);
 690         assert(!ret);
 691
 692         destroy_pid_tracker_node(tracker_node);
 693 end:
 694         return retval;
 695 }
 696
 697 /*
 698  * The session lock is held when calling this function.
 699  */
 700 int trace_ust_pid_tracker_lookup(struct ltt_ust_session *session, int pid)
 701 {
 702         struct lttng_ht_iter iter;
 703
 704         if (!session->pid_tracker.ht) {
 705                 return 1;
 706         }
 707         if (pid_tracker_lookup(&session->pid_tracker, pid, &iter)) {
 708                 return 1;
 709         }
 710         return 0;
 711 }
 712
 713 /*
 714  * Called with the session lock held.
 715  */
 716 int trace_ust_track_pid(struct ltt_ust_session *session, int pid)
 717 {
 718         int retval = LTTNG_OK;
 719
 720         if (pid == -1) {
 721                 /* Track all pids: destroy tracker if exists. */
 722                 if (session->pid_tracker.ht) {
 723                         fini_pid_tracker(&session->pid_tracker);
 724                         /* Ensure all apps have session. */
 725                         ust_app_global_update_all(session);
 726                 }
 727         } else {
 728                 int ret;
 729
 730                 if (!session->pid_tracker.ht) {
 731                         /* Create tracker. */
 732                         if (init_pid_tracker(&session->pid_tracker)) {
 733                                 ERR("Error initializing PID tracker");
 734                                 retval = LTTNG_ERR_NOMEM;
 735                                 goto end;
 736                         }
 737                         ret = pid_tracker_add_pid(&session->pid_tracker, pid);
 738                         if (ret != LTTNG_OK) {
 739                                 retval = ret;
 740                                 fini_pid_tracker(&session->pid_tracker);
 741                                 goto end;
 742                         }
 743                         /* Remove all apps from session except pid. */
 744                         ust_app_global_update_all(session);
 745                 } else {
 746                         struct ust_app *app;
 747
 748                         ret = pid_tracker_add_pid(&session->pid_tracker, pid);
 749                         if (ret != LTTNG_OK) {
 750                                 retval = ret;
 751                                 goto end;
 752                         }
 753                         /* Add session to application */
 754                         app = ust_app_find_by_pid(pid);
 755                         if (app) {
 756                                 ust_app_global_update(session, app);
 757                         }
 758                 }
 759         }
 760 end:
 761         return retval;
 762 }
 763
 764 /*
 765  * Called with the session lock held.
 766  */
 767 int trace_ust_untrack_pid(struct ltt_ust_session *session, int pid)
 768 {
 769         int retval = LTTNG_OK;
 770
 771         if (pid == -1) {
 772                 /* Create empty tracker, replace old tracker. */
 773                 struct ust_pid_tracker tmp_tracker;
 774
 775                 tmp_tracker = session->pid_tracker;
 776                 if (init_pid_tracker(&session->pid_tracker)) {
 777                         ERR("Error initializing PID tracker");
 778                         retval = LTTNG_ERR_NOMEM;
 779                         /* Rollback operation. */
 780                         session->pid_tracker = tmp_tracker;
 781                         goto end;
 782                 }
 783                 fini_pid_tracker(&tmp_tracker);
 784
 785                 /* Remove session from all applications */
 786                 ust_app_global_update_all(session);
 787         } else {
 788                 int ret;
 789                 struct ust_app *app;
 790
 791                 if (!session->pid_tracker.ht) {
 792                         retval = LTTNG_ERR_INVALID;
 793                         goto end;
 794                 }
 795                 /* Remove PID from tracker */
 796                 ret = pid_tracker_del_pid(&session->pid_tracker, pid);
 797                 if (ret != LTTNG_OK) {
 798                         retval = ret;
 799                         goto end;
 800                 }
 801                 /* Remove session from application. */
 802                 app = ust_app_find_by_pid(pid);
 803                 if (app) {
 804                         ust_app_global_update(session, app);
 805                 }
 806         }
 807 end:
 808         return retval;
 809 }
 810
 811 /*
 812  * Called with session lock held.
 813  */
 814 ssize_t trace_ust_list_tracker_pids(struct ltt_ust_session *session,
 815                 int32_t **_pids)
 816 {
 817         struct ust_pid_tracker_node *tracker_node;
 818         struct lttng_ht_iter iter;
 819         unsigned long count, i = 0;
 820         long approx[2];
 821         int32_t *pids;
 822         int ret = 0;
 823
 824         if (!session->pid_tracker.ht) {
 825                 /* Tracker disabled. Set first entry to -1. */
 826                 pids = zmalloc(sizeof(*pids));
 827                 if (!pids) {
 828                         ret = -1;
 829                         goto end;
 830                 }
 831                 pids[0] = -1;
 832                 *_pids = pids;
 833                 return 1;
 834         }
 835
 836         rcu_read_lock();
 837         cds_lfht_count_nodes(session->pid_tracker.ht->ht,
 838                 &approx[0], &count, &approx[1]);
 839         pids = zmalloc(sizeof(*pids) * count);
 840         if (!pids) {
 841                 ret = -1;
 842                 goto end;
 843         }
 844         cds_lfht_for_each_entry(session->pid_tracker.ht->ht,
 845                         &iter.iter, tracker_node, node.node) {
 846                 pids[i++] = tracker_node->node.key;
 847         }
 848         *_pids = pids;
 849         ret = count;
 850 end:
 851         rcu_read_unlock();
 852         return ret;
 853 }
 854
 855 /*
 856  * RCU safe free context structure.
 857  */
 858 static void destroy_context_rcu(struct rcu_head *head)
 859 {
 860         struct lttng_ht_node_ulong *node =
 861                 caa_container_of(head, struct lttng_ht_node_ulong, head);
 862         struct ltt_ust_context *ctx =
 863                 caa_container_of(node, struct ltt_ust_context, node);
 864
 865         free(ctx);
 866 }
 867
 868 /*
 869  * Cleanup UST context hash table.
 870  */
 871 static void destroy_contexts(struct lttng_ht *ht)
 872 {
 873         int ret;
 874         struct lttng_ht_node_ulong *node;
 875         struct lttng_ht_iter iter;
 876         struct ltt_ust_context *ctx;
 877
 878         assert(ht);
 879
 880         rcu_read_lock();
 881         cds_lfht_for_each_entry(ht->ht, &iter.iter, node, node) {
 882                 /* Remove from ordered list. */
 883                 ctx = caa_container_of(node, struct ltt_ust_context, node);
 884                 cds_list_del(&ctx->list);
 885                 /* Remove from channel's hash table. */
 886                 ret = lttng_ht_del(ht, &iter);
 887                 if (!ret) {
 888                         call_rcu(&node->head, destroy_context_rcu);
 889                 }
 890         }
 891         rcu_read_unlock();
 892
 893         ht_cleanup_push(ht);
 894 }
 895
 896 /*
 897  * Cleanup ust event structure.
 898  */
 899 void trace_ust_destroy_event(struct ltt_ust_event *event)
 900 {
 901         assert(event);
 902
 903         DBG2("Trace destroy UST event %s", event->attr.name);
 904         free(event->filter_expression);
 905         free(event->filter);
 906         free(event->exclusion);
 907         free(event);
 908 }
 909
 910 /*
 911  * URCU intermediate call to complete destroy event.
 912  */
 913 static void destroy_event_rcu(struct rcu_head *head)
 914 {
 915         struct lttng_ht_node_str *node =
 916                 caa_container_of(head, struct lttng_ht_node_str, head);
 917         struct ltt_ust_event *event =
 918                 caa_container_of(node, struct ltt_ust_event, node);
 919
 920         trace_ust_destroy_event(event);
 921 }
 922
 923 /*
 924  * Cleanup UST events hashtable.
 925  */
 926 static void destroy_events(struct lttng_ht *events)
 927 {
 928         int ret;
 929         struct lttng_ht_node_str *node;
 930         struct lttng_ht_iter iter;
 931
 932         assert(events);
 933
 934         rcu_read_lock();
 935         cds_lfht_for_each_entry(events->ht, &iter.iter, node, node) {
 936                 ret = lttng_ht_del(events, &iter);
 937                 assert(!ret);
 938                 call_rcu(&node->head, destroy_event_rcu);
 939         }
 940         rcu_read_unlock();
 941
 942         ht_cleanup_push(events);
 943 }
 944
 945 /*
 946  * Cleanup ust channel structure.
 947  *
 948  * Should _NOT_ be called with RCU read lock held.
 949  */
 950 static void _trace_ust_destroy_channel(struct ltt_ust_channel *channel)
 951 {
 952         assert(channel);
 953
 954         DBG2("Trace destroy UST channel %s", channel->name);
 955
 956         /* Destroying all events of the channel */
 957         destroy_events(channel->events);
 958         /* Destroying all context of the channel */
 959         destroy_contexts(channel->ctx);
 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         call_rcu(&channel->node.head, destroy_channel_rcu);
 980 }
 981
 982 /*
 983  * Remove an UST channel from a channel HT.
 984  */
 985 void trace_ust_delete_channel(struct lttng_ht *ht,
 986                 struct ltt_ust_channel *channel)
 987 {
 988         int ret;
 989         struct lttng_ht_iter iter;
 990
 991         assert(ht);
 992         assert(channel);
 993
 994         iter.iter.node = &channel->node.node;
 995         ret = lttng_ht_del(ht, &iter);
 996         assert(!ret);
 997 }
 998
 999 /*
1000  * Iterate over a hash table containing channels and cleanup safely.
1001  */
1002 static void destroy_channels(struct lttng_ht *channels)
1003 {
1004         int ret;
1005         struct lttng_ht_node_str *node;
1006         struct lttng_ht_iter iter;
1007
1008         assert(channels);
1009
1010         rcu_read_lock();
1011
1012         cds_lfht_for_each_entry(channels->ht, &iter.iter, node, node) {
1013                 ret = lttng_ht_del(channels, &iter);
1014                 assert(!ret);
1015                 call_rcu(&node->head, destroy_channel_rcu);
1016         }
1017         rcu_read_unlock();
1018
1019         ht_cleanup_push(channels);
1020 }
1021
1022 /*
1023  * Cleanup UST global domain.
1024  */
1025 static void destroy_domain_global(struct ltt_ust_domain_global *dom)
1026 {
1027         assert(dom);
1028
1029         destroy_channels(dom->channels);
1030 }
1031
1032 /*
1033  * Cleanup ust session structure
1034  *
1035  * Should *NOT* be called with RCU read-side lock held.
1036  */
1037 void trace_ust_destroy_session(struct ltt_ust_session *session)
1038 {
1039         struct agent *agt;
1040         struct buffer_reg_uid *reg, *sreg;
1041         struct lttng_ht_iter iter;
1042
1043         assert(session);
1044
1045         DBG2("Trace UST destroy session %" PRIu64, session->id);
1046
1047         /* Cleaning up UST domain */
1048         destroy_domain_global(&session->domain_global);
1049
1050         rcu_read_lock();
1051         cds_lfht_for_each_entry(session->agents->ht, &iter.iter, agt, node.node) {
1052                 int ret = lttng_ht_del(session->agents, &iter);
1053
1054                 assert(!ret);
1055                 agent_destroy(agt);
1056         }
1057         rcu_read_unlock();
1058
1059         ht_cleanup_push(session->agents);
1060
1061         /* Cleanup UID buffer registry object(s). */
1062         cds_list_for_each_entry_safe(reg, sreg, &session->buffer_reg_uid_list,
1063                         lnode) {
1064                 cds_list_del(&reg->lnode);
1065                 buffer_reg_uid_remove(reg);
1066                 buffer_reg_uid_destroy(reg, session->consumer);
1067         }
1068
1069         consumer_destroy_output(session->consumer);
1070         consumer_destroy_output(session->tmp_consumer);
1071
1072         fini_pid_tracker(&session->pid_tracker);
1073
1074         free(session);
1075 }