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 #include "agent.h"
  34
  35 /*
  36  * Match function for the events hash table lookup.
  37  *
  38  * Matches by name only. Used by the disable command.
  39  */
  40 int trace_ust_ht_match_event_by_name(struct cds_lfht_node *node,
  41                 const void *_key)
  42 {
  43         struct ltt_ust_event *event;
  44         const char *name;
  45
  46         assert(node);
  47         assert(_key);
  48
  49         event = caa_container_of(node, struct ltt_ust_event, node.node);
  50         name = _key;
  51
  52         /* Event name */
  53         if (strncmp(event->attr.name, name, sizeof(event->attr.name)) != 0) {
  54                 goto no_match;
  55         }
  56
  57         /* Match */
  58         return 1;
  59
  60 no_match:
  61         return 0;
  62 }
  63
  64 /*
  65  * Match function for the hash table lookup.
  66  *
  67  * It matches an ust event based on three attributes which are the event name,
  68  * the filter bytecode and the loglevel.
  69  */
  70 int trace_ust_ht_match_event(struct cds_lfht_node *node, const void *_key)
  71 {
  72         struct ltt_ust_event *event;
  73         const struct ltt_ust_ht_key *key;
  74
  75         assert(node);
  76         assert(_key);
  77
  78         event = caa_container_of(node, struct ltt_ust_event, node.node);
  79         key = _key;
  80
  81         /* Match the 4 elements of the key: name, filter, loglevel, exclusions. */
  82
  83         /* Event name */
  84         if (strncmp(event->attr.name, key->name, sizeof(event->attr.name)) != 0) {
  85                 goto no_match;
  86         }
  87
  88         /* Event loglevel. */
  89         if (event->attr.loglevel != key->loglevel) {
  90                 if (event->attr.loglevel_type == LTTNG_UST_LOGLEVEL_ALL
  91                                 && key->loglevel == 0 && event->attr.loglevel == -1) {
  92                         /*
  93                          * Match is accepted. This is because on event creation, the
  94                          * loglevel is set to -1 if the event loglevel type is ALL so 0 and
  95                          * -1 are accepted for this loglevel type since 0 is the one set by
  96                          * the API when receiving an enable event.
  97                          */
  98                 } else {
  99                         goto no_match;
 100                 }
 101         }
 102
 103         /* Only one of the filters is NULL, fail. */
 104         if ((key->filter && !event->filter) || (!key->filter && event->filter)) {
 105                 goto no_match;
 106         }
 107
 108         if (key->filter && event->filter) {
 109                 /* Both filters exists, check length followed by the bytecode. */
 110                 if (event->filter->len != key->filter->len ||
 111                                 memcmp(event->filter->data, key->filter->data,
 112                                         event->filter->len) != 0) {
 113                         goto no_match;
 114                 }
 115         }
 116
 117         /* If only one of the exclusions is NULL, fail. */
 118         if ((key->exclusion && !event->exclusion) || (!key->exclusion && event->exclusion)) {
 119                 goto no_match;
 120         }
 121
 122         if (key->exclusion && event->exclusion) {
 123                 /* Both exclusions exist; check count followed by names. */
 124                 if (event->exclusion->count != key->exclusion->count ||
 125                                 memcmp(event->exclusion->names, key->exclusion->names,
 126                                         event->exclusion->count * LTTNG_SYMBOL_NAME_LEN) != 0) {
 127                         goto no_match;
 128                 }
 129         }
 130         /* Match. */
 131         return 1;
 132
 133 no_match:
 134         return 0;
 135 }
 136
 137 /*
 138  * Find the channel in the hashtable and return channel pointer. RCU read side
 139  * lock MUST be acquired before calling this.
 140  */
 141 struct ltt_ust_channel *trace_ust_find_channel_by_name(struct lttng_ht *ht,
 142                 char *name)
 143 {
 144         struct lttng_ht_node_str *node;
 145         struct lttng_ht_iter iter;
 146
 147         /*
 148          * If we receive an empty string for channel name, it means the
 149          * default channel name is requested.
 150          */
 151         if (name[0] == '\0')
 152                 name = DEFAULT_CHANNEL_NAME;
 153
 154         lttng_ht_lookup(ht, (void *)name, &iter);
 155         node = lttng_ht_iter_get_node_str(&iter);
 156         if (node == NULL) {
 157                 goto error;
 158         }
 159
 160         DBG2("Trace UST channel %s found by name", name);
 161
 162         return caa_container_of(node, struct ltt_ust_channel, node);
 163
 164 error:
 165         DBG2("Trace UST channel %s not found by name", name);
 166         return NULL;
 167 }
 168
 169 /*
 170  * Find the event in the hashtable and return event pointer. RCU read side lock
 171  * MUST be acquired before calling this.
 172  */
 173 struct ltt_ust_event *trace_ust_find_event(struct lttng_ht *ht,
 174                 char *name, struct lttng_filter_bytecode *filter, int loglevel,
 175                 struct lttng_event_exclusion *exclusion)
 176 {
 177         struct lttng_ht_node_str *node;
 178         struct lttng_ht_iter iter;
 179         struct ltt_ust_ht_key key;
 180
 181         assert(name);
 182         assert(ht);
 183
 184         key.name = name;
 185         key.filter = filter;
 186         key.loglevel = loglevel;
 187         key.exclusion = exclusion;
 188
 189         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 190                         trace_ust_ht_match_event, &key, &iter.iter);
 191         node = lttng_ht_iter_get_node_str(&iter);
 192         if (node == NULL) {
 193                 goto error;
 194         }
 195
 196         DBG2("Trace UST event %s found", key.name);
 197
 198         return caa_container_of(node, struct ltt_ust_event, node);
 199
 200 error:
 201         DBG2("Trace UST event %s NOT found", key.name);
 202         return NULL;
 203 }
 204
 205 /*
 206  * Lookup an agent in the session agents hash table by domain type and return
 207  * the object if found else NULL.
 208  *
 209  * RCU read side lock must be acquired before calling and only released
 210  * once the agent is no longer in scope or being used.
 211  */
 212 struct agent *trace_ust_find_agent(struct ltt_ust_session *session,
 213                 enum lttng_domain_type domain_type)
 214 {
 215         struct agent *agt = NULL;
 216         struct lttng_ht_node_u64 *node;
 217         struct lttng_ht_iter iter;
 218         uint64_t key;
 219
 220         assert(session);
 221
 222         DBG3("Trace ust agent lookup for domain %d", domain_type);
 223
 224         key = domain_type;
 225
 226         lttng_ht_lookup(session->agents, &key, &iter);
 227         node = lttng_ht_iter_get_node_u64(&iter);
 228         if (!node) {
 229                 goto end;
 230         }
 231         agt = caa_container_of(node, struct agent, node);
 232
 233 end:
 234         return agt;
 235 }
 236
 237 /*
 238  * Allocate and initialize a ust session data structure.
 239  *
 240  * Return pointer to structure or NULL.
 241  */
 242 struct ltt_ust_session *trace_ust_create_session(uint64_t session_id)
 243 {
 244         struct ltt_ust_session *lus;
 245
 246         /* Allocate a new ltt ust session */
 247         lus = zmalloc(sizeof(struct ltt_ust_session));
 248         if (lus == NULL) {
 249                 PERROR("create ust session zmalloc");
 250                 goto error;
 251         }
 252
 253         /* Init data structure */
 254         lus->id = session_id;
 255         lus->active = 0;
 256
 257         /* Set default metadata channel attribute. */
 258         lus->metadata_attr.overwrite = DEFAULT_CHANNEL_OVERWRITE;
 259         lus->metadata_attr.subbuf_size = default_get_metadata_subbuf_size();
 260         lus->metadata_attr.num_subbuf = DEFAULT_METADATA_SUBBUF_NUM;
 261         lus->metadata_attr.switch_timer_interval = DEFAULT_METADATA_SWITCH_TIMER;
 262         lus->metadata_attr.read_timer_interval = DEFAULT_METADATA_READ_TIMER;
 263         lus->metadata_attr.output = LTTNG_UST_MMAP;
 264
 265         /*
 266          * Default buffer type. This can be changed through an enable channel
 267          * requesting a different type. Note that this can only be changed once
 268          * during the session lifetime which is at the first enable channel and
 269          * only before start. The flag buffer_type_changed indicates the status.
 270          */
 271         lus->buffer_type = LTTNG_BUFFER_PER_UID;
 272         /* Once set to 1, the buffer_type is immutable for the session. */
 273         lus->buffer_type_changed = 0;
 274         /* Init it in case it get used after allocation. */
 275         CDS_INIT_LIST_HEAD(&lus->buffer_reg_uid_list);
 276
 277         /* Alloc UST global domain channels' HT */
 278         lus->domain_global.channels = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 279         /* Alloc agent hash table. */
 280         lus->agents = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
 281
 282         lus->consumer = consumer_create_output(CONSUMER_DST_LOCAL);
 283         if (lus->consumer == NULL) {
 284                 goto error_consumer;
 285         }
 286
 287         DBG2("UST trace session create successful");
 288
 289         return lus;
 290
 291 error_consumer:
 292         ht_cleanup_push(lus->domain_global.channels);
 293         ht_cleanup_push(lus->agents);
 294         free(lus);
 295 error:
 296         return NULL;
 297 }
 298
 299 /*
 300  * Allocate and initialize a ust channel data structure.
 301  *
 302  * Return pointer to structure or NULL.
 303  */
 304 struct ltt_ust_channel *trace_ust_create_channel(struct lttng_channel *chan,
 305                 enum lttng_domain_type domain)
 306 {
 307         struct ltt_ust_channel *luc;
 308
 309         assert(chan);
 310
 311         luc = zmalloc(sizeof(struct ltt_ust_channel));
 312         if (luc == NULL) {
 313                 PERROR("ltt_ust_channel zmalloc");
 314                 goto error;
 315         }
 316
 317         luc->domain = domain;
 318
 319         /* Copy UST channel attributes */
 320         luc->attr.overwrite = chan->attr.overwrite;
 321         luc->attr.subbuf_size = chan->attr.subbuf_size;
 322         luc->attr.num_subbuf = chan->attr.num_subbuf;
 323         luc->attr.switch_timer_interval = chan->attr.switch_timer_interval;
 324         luc->attr.read_timer_interval = chan->attr.read_timer_interval;
 325         luc->attr.output = (enum lttng_ust_output) chan->attr.output;
 326
 327         /* Translate to UST output enum */
 328         switch (luc->attr.output) {
 329         default:
 330                 luc->attr.output = LTTNG_UST_MMAP;
 331                 break;
 332         }
 333
 334         /*
 335          * If we receive an empty string for channel name, it means the
 336          * default channel name is requested.
 337          */
 338         if (chan->name[0] == '\0') {
 339                 strncpy(luc->name, DEFAULT_CHANNEL_NAME, sizeof(luc->name));
 340         } else {
 341                 /* Copy channel name */
 342                 strncpy(luc->name, chan->name, sizeof(luc->name));
 343         }
 344         luc->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 345
 346         /* Init node */
 347         lttng_ht_node_init_str(&luc->node, luc->name);
 348         CDS_INIT_LIST_HEAD(&luc->ctx_list);
 349
 350         /* Alloc hash tables */
 351         luc->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 352         luc->ctx = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
 353
 354         /* On-disk circular buffer parameters */
 355         luc->tracefile_size = chan->attr.tracefile_size;
 356         luc->tracefile_count = chan->attr.tracefile_count;
 357
 358         DBG2("Trace UST channel %s created", luc->name);
 359
 360 error:
 361         return luc;
 362 }
 363
 364 /*
 365  * Allocate and initialize a ust event. Set name and event type.
 366  * We own filter_expression, filter, and exclusion.
 367  *
 368  * Return pointer to structure or NULL.
 369  */
 370 struct ltt_ust_event *trace_ust_create_event(struct lttng_event *ev,
 371                 char *filter_expression,
 372                 struct lttng_filter_bytecode *filter,
 373                 struct lttng_event_exclusion *exclusion,
 374                 bool internal_event)
 375 {
 376         struct ltt_ust_event *lue;
 377
 378         assert(ev);
 379
 380         lue = zmalloc(sizeof(struct ltt_ust_event));
 381         if (lue == NULL) {
 382                 PERROR("ust event zmalloc");
 383                 goto error;
 384         }
 385
 386         lue->internal = internal_event;
 387
 388         switch (ev->type) {
 389         case LTTNG_EVENT_PROBE:
 390                 lue->attr.instrumentation = LTTNG_UST_PROBE;
 391                 break;
 392         case LTTNG_EVENT_FUNCTION:
 393                 lue->attr.instrumentation = LTTNG_UST_FUNCTION;
 394                 break;
 395         case LTTNG_EVENT_FUNCTION_ENTRY:
 396                 lue->attr.instrumentation = LTTNG_UST_FUNCTION;
 397                 break;
 398         case LTTNG_EVENT_TRACEPOINT:
 399                 lue->attr.instrumentation = LTTNG_UST_TRACEPOINT;
 400                 break;
 401         default:
 402                 ERR("Unknown ust instrumentation type (%d)", ev->type);
 403                 goto error_free_event;
 404         }
 405
 406         /* Copy event name */
 407         strncpy(lue->attr.name, ev->name, LTTNG_UST_SYM_NAME_LEN);
 408         lue->attr.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 409
 410         switch (ev->loglevel_type) {
 411         case LTTNG_EVENT_LOGLEVEL_ALL:
 412                 lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_ALL;
 413                 lue->attr.loglevel = -1;        /* Force to -1 */
 414                 break;
 415         case LTTNG_EVENT_LOGLEVEL_RANGE:
 416                 lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_RANGE;
 417                 lue->attr.loglevel = ev->loglevel;
 418                 break;
 419         case LTTNG_EVENT_LOGLEVEL_SINGLE:
 420                 lue->attr.loglevel_type = LTTNG_UST_LOGLEVEL_SINGLE;
 421                 lue->attr.loglevel = ev->loglevel;
 422                 break;
 423         default:
 424                 ERR("Unknown ust loglevel type (%d)", ev->loglevel_type);
 425                 goto error_free_event;
 426         }
 427
 428         /* Same layout. */
 429         lue->filter_expression = filter_expression;
 430         lue->filter = filter;
 431         lue->exclusion = exclusion;
 432
 433         /* Init node */
 434         lttng_ht_node_init_str(&lue->node, lue->attr.name);
 435
 436         DBG2("Trace UST event %s, loglevel (%d,%d) created",
 437                 lue->attr.name, lue->attr.loglevel_type,
 438                 lue->attr.loglevel);
 439
 440         return lue;
 441
 442 error_free_event:
 443         free(lue);
 444 error:
 445         free(filter_expression);
 446         free(filter);
 447         free(exclusion);
 448         return NULL;
 449 }
 450
 451 static
 452 int trace_ust_context_type_event_to_ust(enum lttng_event_context_type type)
 453 {
 454         int utype;
 455
 456         switch (type) {
 457         case LTTNG_EVENT_CONTEXT_VTID:
 458                 utype = LTTNG_UST_CONTEXT_VTID;
 459                 break;
 460         case LTTNG_EVENT_CONTEXT_VPID:
 461                 utype = LTTNG_UST_CONTEXT_VPID;
 462                 break;
 463         case LTTNG_EVENT_CONTEXT_PTHREAD_ID:
 464                 utype = LTTNG_UST_CONTEXT_PTHREAD_ID;
 465                 break;
 466         case LTTNG_EVENT_CONTEXT_PROCNAME:
 467                 utype = LTTNG_UST_CONTEXT_PROCNAME;
 468                 break;
 469         case LTTNG_EVENT_CONTEXT_IP:
 470                 utype = LTTNG_UST_CONTEXT_IP;
 471                 break;
 472         case LTTNG_EVENT_CONTEXT_PERF_THREAD_COUNTER:
 473                 if (!ustctl_has_perf_counters()) {
 474                         utype = -1;
 475                         WARN("Perf counters not implemented in UST");
 476                 } else {
 477                         utype = LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER;
 478                 }
 479                 break;
 480         default:
 481                 ERR("Invalid UST context");
 482                 utype = -1;
 483                 break;
 484         }
 485         return utype;
 486 }
 487
 488 /*
 489  * Return 1 if contexts match, 0 otherwise.
 490  */
 491 int trace_ust_match_context(struct ltt_ust_context *uctx,
 492                 struct lttng_event_context *ctx)
 493 {
 494         int utype;
 495
 496         utype = trace_ust_context_type_event_to_ust(ctx->ctx);
 497         if (utype < 0) {
 498                 return 0;
 499         }
 500         if (uctx->ctx.ctx != utype) {
 501                 return 0;
 502         }
 503         switch (utype) {
 504         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
 505                 if (uctx->ctx.u.perf_counter.type
 506                                 != ctx->u.perf_counter.type) {
 507                         return 0;
 508                 }
 509                 if (uctx->ctx.u.perf_counter.config
 510                                 != ctx->u.perf_counter.config) {
 511                         return 0;
 512                 }
 513                 if (strncmp(uctx->ctx.u.perf_counter.name,
 514                                 ctx->u.perf_counter.name,
 515                                 LTTNG_UST_SYM_NAME_LEN)) {
 516                         return 0;
 517                 }
 518                 break;
 519         default:
 520                 break;
 521
 522         }
 523         return 1;
 524 }
 525
 526 /*
 527  * Allocate and initialize an UST context.
 528  *
 529  * Return pointer to structure or NULL.
 530  */
 531 struct ltt_ust_context *trace_ust_create_context(
 532                 struct lttng_event_context *ctx)
 533 {
 534         struct ltt_ust_context *uctx;
 535         int utype;
 536
 537         assert(ctx);
 538
 539         utype = trace_ust_context_type_event_to_ust(ctx->ctx);
 540         if (utype < 0) {
 541                 return NULL;
 542         }
 543
 544         uctx = zmalloc(sizeof(struct ltt_ust_context));
 545         if (uctx == NULL) {
 546                 PERROR("zmalloc ltt_ust_context");
 547                 goto error;
 548         }
 549
 550         uctx->ctx.ctx = (enum lttng_ust_context_type) utype;
 551         switch (utype) {
 552         case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
 553                 uctx->ctx.u.perf_counter.type = ctx->u.perf_counter.type;
 554                 uctx->ctx.u.perf_counter.config = ctx->u.perf_counter.config;
 555                 strncpy(uctx->ctx.u.perf_counter.name, ctx->u.perf_counter.name,
 556                                 LTTNG_UST_SYM_NAME_LEN);
 557                 uctx->ctx.u.perf_counter.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 558                 break;
 559         default:
 560                 break;
 561         }
 562         lttng_ht_node_init_ulong(&uctx->node, (unsigned long) uctx->ctx.ctx);
 563
 564         return uctx;
 565
 566 error:
 567         return NULL;
 568 }
 569
 570 static
 571 void destroy_pid_tracker_node_rcu(struct rcu_head *head)
 572 {
 573         struct ust_pid_tracker_node *tracker_node =
 574                 caa_container_of(head, struct ust_pid_tracker_node, node.head);
 575         free(tracker_node);
 576 }
 577
 578 static
 579 void destroy_pid_tracker_node(struct ust_pid_tracker_node *tracker_node)
 580 {
 581
 582         call_rcu(&tracker_node->node.head, destroy_pid_tracker_node_rcu);
 583 }
 584
 585 static
 586 int init_pid_tracker(struct ust_pid_tracker *pid_tracker)
 587 {
 588         int ret = 0;
 589
 590         pid_tracker->ht = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
 591         if (!pid_tracker->ht) {
 592                 ret = -1;
 593                 goto end;
 594         }
 595
 596 end:
 597         return ret;
 598 }
 599
 600 /*
 601  * Teardown pid tracker content, but don't free pid_tracker object.
 602  */
 603 static
 604 void fini_pid_tracker(struct ust_pid_tracker *pid_tracker)
 605 {
 606         struct ust_pid_tracker_node *tracker_node;
 607         struct lttng_ht_iter iter;
 608
 609         if (!pid_tracker->ht) {
 610                 return;
 611         }
 612         rcu_read_lock();
 613         cds_lfht_for_each_entry(pid_tracker->ht->ht,
 614                         &iter.iter, tracker_node, node.node) {
 615                 int ret = lttng_ht_del(pid_tracker->ht, &iter);
 616
 617                 assert(!ret);
 618                 destroy_pid_tracker_node(tracker_node);
 619         }
 620         rcu_read_unlock();
 621         ht_cleanup_push(pid_tracker->ht);
 622         pid_tracker->ht = NULL;
 623 }
 624
 625 static
 626 struct ust_pid_tracker_node *pid_tracker_lookup(
 627                 struct ust_pid_tracker *pid_tracker, int pid,
 628                 struct lttng_ht_iter *iter)
 629 {
 630         unsigned long _pid = (unsigned long) pid;
 631         struct lttng_ht_node_ulong *node;
 632
 633         lttng_ht_lookup(pid_tracker->ht, (void *) _pid, iter);
 634         node = lttng_ht_iter_get_node_ulong(iter);
 635         if (node) {
 636                 return caa_container_of(node, struct ust_pid_tracker_node,
 637                         node);
 638         } else {
 639                 return NULL;
 640         }
 641 }
 642
 643 static
 644 int pid_tracker_add_pid(struct ust_pid_tracker *pid_tracker, int pid)
 645 {
 646         int retval = LTTNG_OK;
 647         struct ust_pid_tracker_node *tracker_node;
 648         struct lttng_ht_iter iter;
 649
 650         if (pid < 0) {
 651                 retval = LTTNG_ERR_INVALID;
 652                 goto end;
 653         }
 654         tracker_node = pid_tracker_lookup(pid_tracker, pid, &iter);
 655         if (tracker_node) {
 656                 /* Already exists. */
 657                 retval = LTTNG_ERR_PID_TRACKED;
 658                 goto end;
 659         }
 660         tracker_node = zmalloc(sizeof(*tracker_node));
 661         if (!tracker_node) {
 662                 retval = LTTNG_ERR_NOMEM;
 663                 goto end;
 664         }
 665         lttng_ht_node_init_ulong(&tracker_node->node, (unsigned long) pid);
 666         lttng_ht_add_unique_ulong(pid_tracker->ht, &tracker_node->node);
 667 end:
 668         return retval;
 669 }
 670
 671 static
 672 int pid_tracker_del_pid(struct ust_pid_tracker *pid_tracker, int pid)
 673 {
 674         int retval = LTTNG_OK, ret;
 675         struct ust_pid_tracker_node *tracker_node;
 676         struct lttng_ht_iter iter;
 677
 678         if (pid < 0) {
 679                 retval = LTTNG_ERR_INVALID;
 680                 goto end;
 681         }
 682         tracker_node = pid_tracker_lookup(pid_tracker, pid, &iter);
 683         if (!tracker_node) {
 684                 /* Not found */
 685                 retval = LTTNG_ERR_PID_NOT_TRACKED;
 686                 goto end;
 687         }
 688         ret = lttng_ht_del(pid_tracker->ht, &iter);
 689         assert(!ret);
 690
 691         destroy_pid_tracker_node(tracker_node);
 692 end:
 693         return retval;
 694 }
 695
 696 /*
 697  * The session lock is held when calling this function.
 698  */
 699 int trace_ust_pid_tracker_lookup(struct ltt_ust_session *session, int pid)
 700 {
 701         struct lttng_ht_iter iter;
 702
 703         if (!session->pid_tracker.ht) {
 704                 return 1;
 705         }
 706         if (pid_tracker_lookup(&session->pid_tracker, pid, &iter)) {
 707                 return 1;
 708         }
 709         return 0;
 710 }
 711
 712 /*
 713  * Called with the session lock held.
 714  */
 715 int trace_ust_track_pid(struct ltt_ust_session *session, int pid)
 716 {
 717         int retval = LTTNG_OK;
 718
 719         if (pid == -1) {
 720                 /* Track all pids: destroy tracker if exists. */
 721                 if (session->pid_tracker.ht) {
 722                         fini_pid_tracker(&session->pid_tracker);
 723                         /* Ensure all apps have session. */
 724                         ust_app_global_update_all(session);
 725                 }
 726         } else {
 727                 int ret;
 728
 729                 if (!session->pid_tracker.ht) {
 730                         /* Create tracker. */
 731                         if (init_pid_tracker(&session->pid_tracker)) {
 732                                 ERR("Error initializing PID tracker");
 733                                 retval = LTTNG_ERR_NOMEM;
 734                                 goto end;
 735                         }
 736                         ret = pid_tracker_add_pid(&session->pid_tracker, pid);
 737                         if (ret != LTTNG_OK) {
 738                                 retval = ret;
 739                                 fini_pid_tracker(&session->pid_tracker);
 740                                 goto end;
 741                         }
 742                         /* Remove all apps from session except pid. */
 743                         ust_app_global_update_all(session);
 744                 } else {
 745                         struct ust_app *app;
 746
 747                         ret = pid_tracker_add_pid(&session->pid_tracker, pid);
 748                         if (ret != LTTNG_OK) {
 749                                 retval = ret;
 750                                 goto end;
 751                         }
 752                         /* Add session to application */
 753                         app = ust_app_find_by_pid(pid);
 754                         if (app) {
 755                                 ust_app_global_update(session, app);
 756                         }
 757                 }
 758         }
 759 end:
 760         return retval;
 761 }
 762
 763 /*
 764  * Called with the session lock held.
 765  */
 766 int trace_ust_untrack_pid(struct ltt_ust_session *session, int pid)
 767 {
 768         int retval = LTTNG_OK;
 769
 770         if (pid == -1) {
 771                 /* Create empty tracker, replace old tracker. */
 772                 struct ust_pid_tracker tmp_tracker;
 773
 774                 tmp_tracker = session->pid_tracker;
 775                 if (init_pid_tracker(&session->pid_tracker)) {
 776                         ERR("Error initializing PID tracker");
 777                         retval = LTTNG_ERR_NOMEM;
 778                         /* Rollback operation. */
 779                         session->pid_tracker = tmp_tracker;
 780                         goto end;
 781                 }
 782                 fini_pid_tracker(&tmp_tracker);
 783
 784                 /* Remove session from all applications */
 785                 ust_app_global_update_all(session);
 786         } else {
 787                 int ret;
 788                 struct ust_app *app;
 789
 790                 if (!session->pid_tracker.ht) {
 791                         retval = LTTNG_ERR_INVALID;
 792                         goto end;
 793                 }
 794                 /* Remove PID from tracker */
 795                 ret = pid_tracker_del_pid(&session->pid_tracker, pid);
 796                 if (ret != LTTNG_OK) {
 797                         retval = ret;
 798                         goto end;
 799                 }
 800                 /* Remove session from application. */
 801                 app = ust_app_find_by_pid(pid);
 802                 if (app) {
 803                         ust_app_global_update(session, app);
 804                 }
 805         }
 806 end:
 807         return retval;
 808 }
 809
 810 /*
 811  * Called with session lock held.
 812  */
 813 ssize_t trace_ust_list_tracker_pids(struct ltt_ust_session *session,
 814                 int32_t **_pids)
 815 {
 816         struct ust_pid_tracker_node *tracker_node;
 817         struct lttng_ht_iter iter;
 818         unsigned long count, i = 0;
 819         long approx[2];
 820         int32_t *pids;
 821         int ret = 0;
 822
 823         if (!session->pid_tracker.ht) {
 824                 /* Tracker disabled. Set first entry to -1. */
 825                 pids = zmalloc(sizeof(*pids));
 826                 if (!pids) {
 827                         ret = -1;
 828                         goto end;
 829                 }
 830                 pids[0] = -1;
 831                 *_pids = pids;
 832                 return 1;
 833         }
 834
 835         rcu_read_lock();
 836         cds_lfht_count_nodes(session->pid_tracker.ht->ht,
 837                 &approx[0], &count, &approx[1]);
 838         pids = zmalloc(sizeof(*pids) * count);
 839         if (!pids) {
 840                 ret = -1;
 841                 goto end;
 842         }
 843         cds_lfht_for_each_entry(session->pid_tracker.ht->ht,
 844                         &iter.iter, tracker_node, node.node) {
 845                 pids[i++] = tracker_node->node.key;
 846         }
 847         *_pids = pids;
 848         ret = count;
 849 end:
 850         rcu_read_unlock();
 851         return ret;
 852 }
 853
 854 /*
 855  * RCU safe free context structure.
 856  */
 857 static void destroy_context_rcu(struct rcu_head *head)
 858 {
 859         struct lttng_ht_node_ulong *node =
 860                 caa_container_of(head, struct lttng_ht_node_ulong, head);
 861         struct ltt_ust_context *ctx =
 862                 caa_container_of(node, struct ltt_ust_context, node);
 863
 864         free(ctx);
 865 }
 866
 867 /*
 868  * Cleanup UST context hash table.
 869  */
 870 static void destroy_contexts(struct lttng_ht *ht)
 871 {
 872         int ret;
 873         struct lttng_ht_node_ulong *node;
 874         struct lttng_ht_iter iter;
 875         struct ltt_ust_context *ctx;
 876
 877         assert(ht);
 878
 879         rcu_read_lock();
 880         cds_lfht_for_each_entry(ht->ht, &iter.iter, node, node) {
 881                 /* Remove from ordered list. */
 882                 ctx = caa_container_of(node, struct ltt_ust_context, node);
 883                 cds_list_del(&ctx->list);
 884                 /* Remove from channel's hash table. */
 885                 ret = lttng_ht_del(ht, &iter);
 886                 if (!ret) {
 887                         call_rcu(&node->head, destroy_context_rcu);
 888                 }
 889         }
 890         rcu_read_unlock();
 891
 892         ht_cleanup_push(ht);
 893 }
 894
 895 /*
 896  * Cleanup ust event structure.
 897  */
 898 void trace_ust_destroy_event(struct ltt_ust_event *event)
 899 {
 900         assert(event);
 901
 902         DBG2("Trace destroy UST event %s", event->attr.name);
 903         free(event->filter_expression);
 904         free(event->filter);
 905         free(event->exclusion);
 906         free(event);
 907 }
 908
 909 /*
 910  * URCU intermediate call to complete destroy event.
 911  */
 912 static void destroy_event_rcu(struct rcu_head *head)
 913 {
 914         struct lttng_ht_node_str *node =
 915                 caa_container_of(head, struct lttng_ht_node_str, head);
 916         struct ltt_ust_event *event =
 917                 caa_container_of(node, struct ltt_ust_event, node);
 918
 919         trace_ust_destroy_event(event);
 920 }
 921
 922 /*
 923  * Cleanup UST events hashtable.
 924  */
 925 static void destroy_events(struct lttng_ht *events)
 926 {
 927         int ret;
 928         struct lttng_ht_node_str *node;
 929         struct lttng_ht_iter iter;
 930
 931         assert(events);
 932
 933         rcu_read_lock();
 934         cds_lfht_for_each_entry(events->ht, &iter.iter, node, node) {
 935                 ret = lttng_ht_del(events, &iter);
 936                 assert(!ret);
 937                 call_rcu(&node->head, destroy_event_rcu);
 938         }
 939         rcu_read_unlock();
 940
 941         ht_cleanup_push(events);
 942 }
 943
 944 /*
 945  * Cleanup ust channel structure.
 946  *
 947  * Should _NOT_ be called with RCU read lock held.
 948  */
 949 static void _trace_ust_destroy_channel(struct ltt_ust_channel *channel)
 950 {
 951         assert(channel);
 952
 953         DBG2("Trace destroy UST channel %s", channel->name);
 954
 955         /* Destroying all events of the channel */
 956         destroy_events(channel->events);
 957         /* Destroying all context of the channel */
 958         destroy_contexts(channel->ctx);
 959
 960         free(channel);
 961 }
 962
 963 /*
 964  * URCU intermediate call to complete destroy channel.
 965  */
 966 static void destroy_channel_rcu(struct rcu_head *head)
 967 {
 968         struct lttng_ht_node_str *node =
 969                 caa_container_of(head, struct lttng_ht_node_str, head);
 970         struct ltt_ust_channel *channel =
 971                 caa_container_of(node, struct ltt_ust_channel, node);
 972
 973         _trace_ust_destroy_channel(channel);
 974 }
 975
 976 void trace_ust_destroy_channel(struct ltt_ust_channel *channel)
 977 {
 978         call_rcu(&channel->node.head, destroy_channel_rcu);
 979 }
 980
 981 /*
 982  * Remove an UST channel from a channel HT.
 983  */
 984 void trace_ust_delete_channel(struct lttng_ht *ht,
 985                 struct ltt_ust_channel *channel)
 986 {
 987         int ret;
 988         struct lttng_ht_iter iter;
 989
 990         assert(ht);
 991         assert(channel);
 992
 993         iter.iter.node = &channel->node.node;
 994         ret = lttng_ht_del(ht, &iter);
 995         assert(!ret);
 996 }
 997
 998 /*
 999  * Iterate over a hash table containing channels and cleanup safely.
1000  */
1001 static void destroy_channels(struct lttng_ht *channels)
1002 {
1003         int ret;
1004         struct lttng_ht_node_str *node;
1005         struct lttng_ht_iter iter;
1006
1007         assert(channels);
1008
1009         rcu_read_lock();
1010
1011         cds_lfht_for_each_entry(channels->ht, &iter.iter, node, node) {
1012                 ret = lttng_ht_del(channels, &iter);
1013                 assert(!ret);
1014                 call_rcu(&node->head, destroy_channel_rcu);
1015         }
1016         rcu_read_unlock();
1017
1018         ht_cleanup_push(channels);
1019 }
1020
1021 /*
1022  * Cleanup UST global domain.
1023  */
1024 static void destroy_domain_global(struct ltt_ust_domain_global *dom)
1025 {
1026         assert(dom);
1027
1028         destroy_channels(dom->channels);
1029 }
1030
1031 /*
1032  * Cleanup ust session structure
1033  *
1034  * Should *NOT* be called with RCU read-side lock held.
1035  */
1036 void trace_ust_destroy_session(struct ltt_ust_session *session)
1037 {
1038         struct agent *agt;
1039         struct buffer_reg_uid *reg, *sreg;
1040         struct lttng_ht_iter iter;
1041
1042         assert(session);
1043
1044         DBG2("Trace UST destroy session %" PRIu64, session->id);
1045
1046         /* Cleaning up UST domain */
1047         destroy_domain_global(&session->domain_global);
1048
1049         rcu_read_lock();
1050         cds_lfht_for_each_entry(session->agents->ht, &iter.iter, agt, node.node) {
1051                 int ret = lttng_ht_del(session->agents, &iter);
1052
1053                 assert(!ret);
1054                 agent_destroy(agt);
1055         }
1056         rcu_read_unlock();
1057
1058         ht_cleanup_push(session->agents);
1059
1060         /* Cleanup UID buffer registry object(s). */
1061         cds_list_for_each_entry_safe(reg, sreg, &session->buffer_reg_uid_list,
1062                         lnode) {
1063                 cds_list_del(&reg->lnode);
1064                 buffer_reg_uid_remove(reg);
1065                 buffer_reg_uid_destroy(reg, session->consumer);
1066         }
1067
1068         consumer_output_put(session->consumer);
1069
1070         fini_pid_tracker(&session->pid_tracker);
1071
1072         free(session);
1073 }