src/bin/lttng-sessiond/ust-registry.c

   1 /*
   2  * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License, version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc., 51
  15  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _LGPL_SOURCE
  19 #include <assert.h>
  20 #include <inttypes.h>
  21
  22 #include <common/common.h>
  23 #include <common/hashtable/utils.h>
  24 #include <lttng/lttng.h>
  25
  26 #include "ust-registry.h"
  27 #include "ust-app.h"
  28 #include "utils.h"
  29 #include "lttng-sessiond.h"
  30 #include "notification-thread-commands.h"
  31
  32 /*
  33  * Hash table match function for event in the registry.
  34  */
  35 static int ht_match_event(struct cds_lfht_node *node, const void *_key)
  36 {
  37         struct ust_registry_event *event;
  38         const struct ust_registry_event *key;
  39
  40         assert(node);
  41         assert(_key);
  42
  43         event = caa_container_of(node, struct ust_registry_event, node.node);
  44         assert(event);
  45         key = _key;
  46
  47         /* It has to be a perfect match. */
  48         if (strncmp(event->name, key->name, sizeof(event->name))) {
  49                 goto no_match;
  50         }
  51
  52         /* It has to be a perfect match. */
  53         if (strncmp(event->signature, key->signature,
  54                         strlen(event->signature))) {
  55                 goto no_match;
  56         }
  57
  58         /* Match */
  59         return 1;
  60
  61 no_match:
  62         return 0;
  63 }
  64
  65 static unsigned long ht_hash_event(void *_key, unsigned long seed)
  66 {
  67         uint64_t xored_key;
  68         struct ust_registry_event *key = _key;
  69
  70         assert(key);
  71
  72         xored_key = (uint64_t) (hash_key_str(key->name, seed) ^
  73                         hash_key_str(key->signature, seed));
  74
  75         return hash_key_u64(&xored_key, seed);
  76 }
  77
  78 static int compare_enums(const struct ust_registry_enum *reg_enum_a,
  79                 const struct ust_registry_enum *reg_enum_b)
  80 {
  81         int ret = 0;
  82         size_t i;
  83
  84         assert(strcmp(reg_enum_a->name, reg_enum_b->name) == 0);
  85         if (reg_enum_a->nr_entries != reg_enum_b->nr_entries) {
  86                 ret = -1;
  87                 goto end;
  88         }
  89         for (i = 0; i < reg_enum_a->nr_entries; i++) {
  90                 const struct ustctl_enum_entry *entries_a, *entries_b;
  91
  92                 entries_a = &reg_enum_a->entries[i];
  93                 entries_b = &reg_enum_b->entries[i];
  94                 if (entries_a->start.value != entries_b->start.value) {
  95                         ret = -1;
  96                         goto end;
  97                 }
  98                 if (entries_a->end.value != entries_b->end.value) {
  99                         ret = -1;
 100                         goto end;
 101                 }
 102                 if (entries_a->start.signedness != entries_b->start.signedness) {
 103                         ret = -1;
 104                         goto end;
 105                 }
 106                 if (entries_a->end.signedness != entries_b->end.signedness) {
 107                         ret = -1;
 108                         goto end;
 109                 }
 110
 111                 if (strcmp(entries_a->string, entries_b->string)) {
 112                         ret = -1;
 113                         goto end;
 114                 }
 115         }
 116 end:
 117         return ret;
 118 }
 119
 120 /*
 121  * Hash table match function for enumerations in the session. Match is
 122  * performed on enumeration name, and confirmed by comparing the enum
 123  * entries.
 124  */
 125 static int ht_match_enum(struct cds_lfht_node *node, const void *_key)
 126 {
 127         struct ust_registry_enum *_enum;
 128         const struct ust_registry_enum *key;
 129
 130         assert(node);
 131         assert(_key);
 132
 133         _enum = caa_container_of(node, struct ust_registry_enum,
 134                         node.node);
 135         assert(_enum);
 136         key = _key;
 137
 138         if (strncmp(_enum->name, key->name, LTTNG_UST_SYM_NAME_LEN)) {
 139                 goto no_match;
 140         }
 141         if (compare_enums(_enum, key)) {
 142                 goto no_match;
 143         }
 144
 145         /* Match. */
 146         return 1;
 147
 148 no_match:
 149         return 0;
 150 }
 151
 152 /*
 153  * Hash table match function for enumerations in the session. Match is
 154  * performed by enumeration ID.
 155  */
 156 static int ht_match_enum_id(struct cds_lfht_node *node, const void *_key)
 157 {
 158         struct ust_registry_enum *_enum;
 159         const struct ust_registry_enum *key = _key;
 160
 161         assert(node);
 162         assert(_key);
 163
 164         _enum = caa_container_of(node, struct ust_registry_enum, node.node);
 165         assert(_enum);
 166
 167         if (_enum->id != key->id) {
 168                 goto no_match;
 169         }
 170
 171         /* Match. */
 172         return 1;
 173
 174 no_match:
 175         return 0;
 176 }
 177
 178 /*
 179  * Hash table hash function for enumerations in the session. The
 180  * enumeration name is used for hashing.
 181  */
 182 static unsigned long ht_hash_enum(void *_key, unsigned long seed)
 183 {
 184         struct ust_registry_enum *key = _key;
 185
 186         assert(key);
 187         return hash_key_str(key->name, seed);
 188 }
 189
 190 /*
 191  * Return negative value on error, 0 if OK.
 192  *
 193  * TODO: we could add stricter verification of more types to catch
 194  * errors in liblttng-ust implementation earlier than consumption by the
 195  * trace reader.
 196  */
 197 static
 198 int validate_event_field(struct ustctl_field *field,
 199                 const char *event_name,
 200                 struct ust_app *app)
 201 {
 202         int ret = 0;
 203
 204         switch(field->type.atype) {
 205         case ustctl_atype_integer:
 206         case ustctl_atype_enum:
 207         case ustctl_atype_array:
 208         case ustctl_atype_sequence:
 209         case ustctl_atype_string:
 210         case ustctl_atype_variant:
 211                 break;
 212         case ustctl_atype_struct:
 213                 if (field->type.u._struct.nr_fields != 0) {
 214                         WARN("Unsupported non-empty struct field.");
 215                         ret = -EINVAL;
 216                         goto end;
 217                 }
 218                 break;
 219
 220         case ustctl_atype_float:
 221                 switch (field->type.u.basic._float.mant_dig) {
 222                 case 0:
 223                         WARN("UST application '%s' (pid: %d) has unknown float mantissa '%u' "
 224                                 "in field '%s', rejecting event '%s'",
 225                                 app->name, app->pid,
 226                                 field->type.u.basic._float.mant_dig,
 227                                 field->name,
 228                                 event_name);
 229                         ret = -EINVAL;
 230                         goto end;
 231                 default:
 232                         break;
 233                 }
 234                 break;
 235
 236         default:
 237                 ret = -ENOENT;
 238                 goto end;
 239         }
 240 end:
 241         return ret;
 242 }
 243
 244 static
 245 int validate_event_fields(size_t nr_fields, struct ustctl_field *fields,
 246                 const char *event_name, struct ust_app *app)
 247 {
 248         unsigned int i;
 249
 250         for (i = 0; i < nr_fields; i++) {
 251                 if (validate_event_field(&fields[i], event_name, app) < 0)
 252                         return -EINVAL;
 253         }
 254         return 0;
 255 }
 256
 257 /*
 258  * Allocate event and initialize it. This does NOT set a valid event id from a
 259  * registry.
 260  */
 261 static struct ust_registry_event *alloc_event(int session_objd,
 262                 int channel_objd, char *name, char *sig, size_t nr_fields,
 263                 struct ustctl_field *fields, int loglevel_value,
 264                 char *model_emf_uri, struct ust_app *app)
 265 {
 266         struct ust_registry_event *event = NULL;
 267
 268         /*
 269          * Ensure that the field content is valid.
 270          */
 271         if (validate_event_fields(nr_fields, fields, name, app) < 0) {
 272                 return NULL;
 273         }
 274
 275         event = zmalloc(sizeof(*event));
 276         if (!event) {
 277                 PERROR("zmalloc ust registry event");
 278                 goto error;
 279         }
 280
 281         event->session_objd = session_objd;
 282         event->channel_objd = channel_objd;
 283         /* Allocated by ustctl. */
 284         event->signature = sig;
 285         event->nr_fields = nr_fields;
 286         event->fields = fields;
 287         event->loglevel_value = loglevel_value;
 288         event->model_emf_uri = model_emf_uri;
 289         if (name) {
 290                 /* Copy event name and force NULL byte. */
 291                 strncpy(event->name, name, sizeof(event->name));
 292                 event->name[sizeof(event->name) - 1] = '\0';
 293         }
 294         cds_lfht_node_init(&event->node.node);
 295
 296 error:
 297         return event;
 298 }
 299
 300 /*
 301  * Free event data structure. This does NOT delete it from any hash table. It's
 302  * safe to pass a NULL pointer. This shoudl be called inside a call RCU if the
 303  * event is previously deleted from a rcu hash table.
 304  */
 305 static void destroy_event(struct ust_registry_event *event)
 306 {
 307         if (!event) {
 308                 return;
 309         }
 310
 311         free(event->fields);
 312         free(event->model_emf_uri);
 313         free(event->signature);
 314         free(event);
 315 }
 316
 317 /*
 318  * Destroy event function call of the call RCU.
 319  */
 320 static void destroy_event_rcu(struct rcu_head *head)
 321 {
 322         struct lttng_ht_node_u64 *node =
 323                 caa_container_of(head, struct lttng_ht_node_u64, head);
 324         struct ust_registry_event *event =
 325                 caa_container_of(node, struct ust_registry_event, node);
 326
 327         destroy_event(event);
 328 }
 329
 330 /*
 331  * Find an event using the name and signature in the given registry. RCU read
 332  * side lock MUST be acquired before calling this function and as long as the
 333  * event reference is kept by the caller.
 334  *
 335  * On success, the event pointer is returned else NULL.
 336  */
 337 struct ust_registry_event *ust_registry_find_event(
 338                 struct ust_registry_channel *chan, char *name, char *sig)
 339 {
 340         struct lttng_ht_node_u64 *node;
 341         struct lttng_ht_iter iter;
 342         struct ust_registry_event *event = NULL;
 343         struct ust_registry_event key;
 344
 345         assert(chan);
 346         assert(name);
 347         assert(sig);
 348
 349         /* Setup key for the match function. */
 350         strncpy(key.name, name, sizeof(key.name));
 351         key.name[sizeof(key.name) - 1] = '\0';
 352         key.signature = sig;
 353
 354         cds_lfht_lookup(chan->ht->ht, chan->ht->hash_fct(&key, lttng_ht_seed),
 355                         chan->ht->match_fct, &key, &iter.iter);
 356         node = lttng_ht_iter_get_node_u64(&iter);
 357         if (!node) {
 358                 goto end;
 359         }
 360         event = caa_container_of(node, struct ust_registry_event, node);
 361
 362 end:
 363         return event;
 364 }
 365
 366 /*
 367  * Create a ust_registry_event from the given parameters and add it to the
 368  * registry hash table. If event_id is valid, it is set with the newly created
 369  * event id.
 370  *
 371  * On success, return 0 else a negative value. The created event MUST be unique
 372  * so on duplicate entry -EINVAL is returned. On error, event_id is untouched.
 373  *
 374  * Should be called with session registry mutex held.
 375  */
 376 int ust_registry_create_event(struct ust_registry_session *session,
 377                 uint64_t chan_key, int session_objd, int channel_objd, char *name,
 378                 char *sig, size_t nr_fields, struct ustctl_field *fields,
 379                 int loglevel_value, char *model_emf_uri, int buffer_type,
 380                 uint32_t *event_id_p, struct ust_app *app)
 381 {
 382         int ret;
 383         uint32_t event_id;
 384         struct cds_lfht_node *nptr;
 385         struct ust_registry_event *event = NULL;
 386         struct ust_registry_channel *chan;
 387
 388         assert(session);
 389         assert(name);
 390         assert(sig);
 391         assert(event_id_p);
 392
 393         rcu_read_lock();
 394
 395         /*
 396          * This should not happen but since it comes from the UST tracer, an
 397          * external party, don't assert and simply validate values.
 398          */
 399         if (session_objd < 0 || channel_objd < 0) {
 400                 ret = -EINVAL;
 401                 goto error_free;
 402         }
 403
 404         chan = ust_registry_channel_find(session, chan_key);
 405         if (!chan) {
 406                 ret = -EINVAL;
 407                 goto error_free;
 408         }
 409
 410         /* Check if we've reached the maximum possible id. */
 411         if (ust_registry_is_max_id(chan->used_event_id)) {
 412                 ret = -ENOENT;
 413                 goto error_free;
 414         }
 415
 416         event = alloc_event(session_objd, channel_objd, name, sig, nr_fields,
 417                         fields, loglevel_value, model_emf_uri, app);
 418         if (!event) {
 419                 ret = -ENOMEM;
 420                 goto error_free;
 421         }
 422
 423         DBG3("UST registry creating event with event: %s, sig: %s, id: %u, "
 424                         "chan_objd: %u, sess_objd: %u, chan_id: %u", event->name,
 425                         event->signature, event->id, event->channel_objd,
 426                         event->session_objd, chan->chan_id);
 427
 428         /*
 429          * This is an add unique with a custom match function for event. The node
 430          * are matched using the event name and signature.
 431          */
 432         nptr = cds_lfht_add_unique(chan->ht->ht, chan->ht->hash_fct(event,
 433                                 lttng_ht_seed), chan->ht->match_fct, event, &event->node.node);
 434         if (nptr != &event->node.node) {
 435                 if (buffer_type == LTTNG_BUFFER_PER_UID) {
 436                         /*
 437                          * This is normal, we just have to send the event id of the
 438                          * returned node and make sure we destroy the previously allocated
 439                          * event object.
 440                          */
 441                         destroy_event(event);
 442                         event = caa_container_of(nptr, struct ust_registry_event,
 443                                         node.node);
 444                         assert(event);
 445                         event_id = event->id;
 446                 } else {
 447                         ERR("UST registry create event add unique failed for event: %s, "
 448                                         "sig: %s, id: %u, chan_objd: %u, sess_objd: %u",
 449                                         event->name, event->signature, event->id,
 450                                         event->channel_objd, event->session_objd);
 451                         ret = -EINVAL;
 452                         goto error_unlock;
 453                 }
 454         } else {
 455                 /* Request next event id if the node was successfully added. */
 456                 event_id = event->id = ust_registry_get_next_event_id(chan);
 457         }
 458
 459         *event_id_p = event_id;
 460
 461         if (!event->metadata_dumped) {
 462                 /* Append to metadata */
 463                 ret = ust_metadata_event_statedump(session, chan, event);
 464                 if (ret) {
 465                         ERR("Error appending event metadata (errno = %d)", ret);
 466                         rcu_read_unlock();
 467                         return ret;
 468                 }
 469         }
 470
 471         rcu_read_unlock();
 472         return 0;
 473
 474 error_free:
 475         free(sig);
 476         free(fields);
 477         free(model_emf_uri);
 478 error_unlock:
 479         rcu_read_unlock();
 480         destroy_event(event);
 481         return ret;
 482 }
 483
 484 /*
 485  * For a given event in a registry, delete the entry and destroy the event.
 486  * This MUST be called within a RCU read side lock section.
 487  */
 488 void ust_registry_destroy_event(struct ust_registry_channel *chan,
 489                 struct ust_registry_event *event)
 490 {
 491         int ret;
 492         struct lttng_ht_iter iter;
 493
 494         assert(chan);
 495         assert(event);
 496
 497         /* Delete the node first. */
 498         iter.iter.node = &event->node.node;
 499         ret = lttng_ht_del(chan->ht, &iter);
 500         assert(!ret);
 501
 502         call_rcu(&event->node.head, destroy_event_rcu);
 503
 504         return;
 505 }
 506
 507 static void destroy_enum(struct ust_registry_enum *reg_enum)
 508 {
 509         if (!reg_enum) {
 510                 return;
 511         }
 512         free(reg_enum->entries);
 513         free(reg_enum);
 514 }
 515
 516 static void destroy_enum_rcu(struct rcu_head *head)
 517 {
 518         struct ust_registry_enum *reg_enum =
 519                 caa_container_of(head, struct ust_registry_enum, rcu_head);
 520
 521         destroy_enum(reg_enum);
 522 }
 523
 524 /*
 525  * Lookup enumeration by name and comparing enumeration entries.
 526  * Needs to be called from RCU read-side critical section.
 527  */
 528 struct ust_registry_enum *
 529         ust_registry_lookup_enum(struct ust_registry_session *session,
 530                 const struct ust_registry_enum *reg_enum_lookup)
 531 {
 532         struct ust_registry_enum *reg_enum = NULL;
 533         struct lttng_ht_node_str *node;
 534         struct lttng_ht_iter iter;
 535
 536         cds_lfht_lookup(session->enums->ht,
 537                         ht_hash_enum((void *) &reg_enum_lookup, lttng_ht_seed),
 538                         ht_match_enum, &reg_enum_lookup, &iter.iter);
 539         node = lttng_ht_iter_get_node_str(&iter);
 540         if (!node) {
 541                 goto end;
 542         }
 543         reg_enum = caa_container_of(node, struct ust_registry_enum, node);
 544 end:
 545         return reg_enum;
 546 }
 547
 548 /*
 549  * Lookup enumeration by enum ID.
 550  * Needs to be called from RCU read-side critical section.
 551  */
 552 struct ust_registry_enum *
 553         ust_registry_lookup_enum_by_id(struct ust_registry_session *session,
 554                 const char *enum_name, uint64_t enum_id)
 555 {
 556         struct ust_registry_enum *reg_enum = NULL;
 557         struct lttng_ht_node_str *node;
 558         struct lttng_ht_iter iter;
 559         struct ust_registry_enum reg_enum_lookup;
 560
 561         memset(&reg_enum_lookup, 0, sizeof(reg_enum_lookup));
 562         strncpy(reg_enum_lookup.name, enum_name, LTTNG_UST_SYM_NAME_LEN);
 563         reg_enum_lookup.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 564         reg_enum_lookup.id = enum_id;
 565         cds_lfht_lookup(session->enums->ht,
 566                         ht_hash_enum((void *) &reg_enum_lookup, lttng_ht_seed),
 567                         ht_match_enum_id, &reg_enum_lookup, &iter.iter);
 568         node = lttng_ht_iter_get_node_str(&iter);
 569         if (!node) {
 570                 goto end;
 571         }
 572         reg_enum = caa_container_of(node, struct ust_registry_enum, node);
 573 end:
 574         return reg_enum;
 575 }
 576
 577 /*
 578  * Create a ust_registry_enum from the given parameters and add it to the
 579  * registry hash table, or find it if already there.
 580  *
 581  * On success, return 0 else a negative value.
 582  *
 583  * Should be called with session registry mutex held.
 584  *
 585  * We receive ownership of entries.
 586  */
 587 int ust_registry_create_or_find_enum(struct ust_registry_session *session,
 588                 int session_objd, char *enum_name,
 589                 struct ustctl_enum_entry *entries, size_t nr_entries,
 590                 uint64_t *enum_id)
 591 {
 592         int ret = 0;
 593         struct cds_lfht_node *nodep;
 594         struct ust_registry_enum *reg_enum = NULL, *old_reg_enum;
 595
 596         assert(session);
 597         assert(enum_name);
 598
 599         rcu_read_lock();
 600
 601         /*
 602          * This should not happen but since it comes from the UST tracer, an
 603          * external party, don't assert and simply validate values.
 604          */
 605         if (session_objd < 0) {
 606                 ret = -EINVAL;
 607                 goto end;
 608         }
 609
 610         /* Check if the enumeration was already dumped */
 611         reg_enum = zmalloc(sizeof(*reg_enum));
 612         if (!reg_enum) {
 613                 PERROR("zmalloc ust registry enumeration");
 614                 ret = -ENOMEM;
 615                 goto end;
 616         }
 617         strncpy(reg_enum->name, enum_name, LTTNG_UST_SYM_NAME_LEN);
 618         reg_enum->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 619         /* entries will be owned by reg_enum. */
 620         reg_enum->entries = entries;
 621         reg_enum->nr_entries = nr_entries;
 622         entries = NULL;
 623
 624         old_reg_enum = ust_registry_lookup_enum(session, reg_enum);
 625         if (old_reg_enum) {
 626                 DBG("enum %s already in sess_objd: %u", enum_name, session_objd);
 627                 /* Fall through. Use prior enum. */
 628                 destroy_enum(reg_enum);
 629                 reg_enum = old_reg_enum;
 630         } else {
 631                 DBG("UST registry creating enum: %s, sess_objd: %u",
 632                                 enum_name, session_objd);
 633                 if (session->next_enum_id == -1ULL) {
 634                         ret = -EOVERFLOW;
 635                         destroy_enum(reg_enum);
 636                         goto end;
 637                 }
 638                 reg_enum->id = session->next_enum_id++;
 639                 cds_lfht_node_init(&reg_enum->node.node);
 640                 nodep = cds_lfht_add_unique(session->enums->ht,
 641                                 ht_hash_enum(reg_enum, lttng_ht_seed),
 642                                 ht_match_enum_id, reg_enum,
 643                                 &reg_enum->node.node);
 644                 assert(nodep == &reg_enum->node.node);
 645         }
 646         DBG("UST registry reply with enum %s with id %" PRIu64 " in sess_objd: %u",
 647                         enum_name, reg_enum->id, session_objd);
 648         *enum_id = reg_enum->id;
 649 end:
 650         free(entries);
 651         rcu_read_unlock();
 652         return ret;
 653 }
 654
 655 /*
 656  * For a given enumeration in a registry, delete the entry and destroy
 657  * the enumeration.
 658  * This MUST be called within a RCU read side lock section.
 659  */
 660 void ust_registry_destroy_enum(struct ust_registry_session *reg_session,
 661                 struct ust_registry_enum *reg_enum)
 662 {
 663         int ret;
 664         struct lttng_ht_iter iter;
 665
 666         assert(reg_session);
 667         assert(reg_enum);
 668
 669         /* Delete the node first. */
 670         iter.iter.node = &reg_enum->node.node;
 671         ret = lttng_ht_del(reg_session->enums, &iter);
 672         assert(!ret);
 673         call_rcu(&reg_enum->rcu_head, destroy_enum_rcu);
 674 }
 675
 676 /*
 677  * We need to execute ht_destroy outside of RCU read-side critical
 678  * section and outside of call_rcu thread, so we postpone its execution
 679  * using ht_cleanup_push. It is simpler than to change the semantic of
 680  * the many callers of delete_ust_app_session().
 681  */
 682 static
 683 void destroy_channel_rcu(struct rcu_head *head)
 684 {
 685         struct ust_registry_channel *chan =
 686                 caa_container_of(head, struct ust_registry_channel, rcu_head);
 687
 688         if (chan->ht) {
 689                 ht_cleanup_push(chan->ht);
 690         }
 691         free(chan->ctx_fields);
 692         free(chan);
 693 }
 694
 695 /*
 696  * Destroy every element of the registry and free the memory. This does NOT
 697  * free the registry pointer since it might not have been allocated before so
 698  * it's the caller responsability.
 699  */
 700 static void destroy_channel(struct ust_registry_channel *chan, bool notif)
 701 {
 702         struct lttng_ht_iter iter;
 703         struct ust_registry_event *event;
 704         enum lttng_error_code cmd_ret;
 705
 706         assert(chan);
 707
 708         if (notif) {
 709                 cmd_ret = notification_thread_command_remove_channel(
 710                                 notification_thread_handle, chan->consumer_key,
 711                                 LTTNG_DOMAIN_UST);
 712                 if (cmd_ret != LTTNG_OK) {
 713                         ERR("Failed to remove channel from notification thread");
 714                 }
 715         }
 716
 717         rcu_read_lock();
 718         /* Destroy all event associated with this registry. */
 719         cds_lfht_for_each_entry(chan->ht->ht, &iter.iter, event, node.node) {
 720                 /* Delete the node from the ht and free it. */
 721                 ust_registry_destroy_event(chan, event);
 722         }
 723         rcu_read_unlock();
 724         call_rcu(&chan->rcu_head, destroy_channel_rcu);
 725 }
 726
 727 /*
 728  * Initialize registry with default values.
 729  */
 730 int ust_registry_channel_add(struct ust_registry_session *session,
 731                 uint64_t key)
 732 {
 733         int ret = 0;
 734         struct ust_registry_channel *chan;
 735
 736         assert(session);
 737
 738         chan = zmalloc(sizeof(*chan));
 739         if (!chan) {
 740                 PERROR("zmalloc ust registry channel");
 741                 ret = -ENOMEM;
 742                 goto error_alloc;
 743         }
 744
 745         chan->ht = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 746         if (!chan->ht) {
 747                 ret = -ENOMEM;
 748                 goto error;
 749         }
 750
 751         /* Set custom match function. */
 752         chan->ht->match_fct = ht_match_event;
 753         chan->ht->hash_fct = ht_hash_event;
 754
 755         /*
 756          * Assign a channel ID right now since the event notification comes
 757          * *before* the channel notify so the ID needs to be set at this point so
 758          * the metadata can be dumped for that event.
 759          */
 760         if (ust_registry_is_max_id(session->used_channel_id)) {
 761                 ret = -1;
 762                 goto error;
 763         }
 764         chan->chan_id = ust_registry_get_next_chan_id(session);
 765
 766         rcu_read_lock();
 767         lttng_ht_node_init_u64(&chan->node, key);
 768         lttng_ht_add_unique_u64(session->channels, &chan->node);
 769         rcu_read_unlock();
 770
 771         return 0;
 772
 773 error:
 774         destroy_channel(chan, false);
 775 error_alloc:
 776         return ret;
 777 }
 778
 779 /*
 780  * Find a channel in the given registry. RCU read side lock MUST be acquired
 781  * before calling this function and as long as the event reference is kept by
 782  * the caller.
 783  *
 784  * On success, the pointer is returned else NULL.
 785  */
 786 struct ust_registry_channel *ust_registry_channel_find(
 787                 struct ust_registry_session *session, uint64_t key)
 788 {
 789         struct lttng_ht_node_u64 *node;
 790         struct lttng_ht_iter iter;
 791         struct ust_registry_channel *chan = NULL;
 792
 793         assert(session);
 794         assert(session->channels);
 795
 796         DBG3("UST registry channel finding key %" PRIu64, key);
 797
 798         lttng_ht_lookup(session->channels, &key, &iter);
 799         node = lttng_ht_iter_get_node_u64(&iter);
 800         if (!node) {
 801                 goto end;
 802         }
 803         chan = caa_container_of(node, struct ust_registry_channel, node);
 804
 805 end:
 806         return chan;
 807 }
 808
 809 /*
 810  * Remove channel using key from registry and free memory.
 811  */
 812 void ust_registry_channel_del_free(struct ust_registry_session *session,
 813                 uint64_t key, bool notif)
 814 {
 815         struct lttng_ht_iter iter;
 816         struct ust_registry_channel *chan;
 817         int ret;
 818
 819         assert(session);
 820
 821         rcu_read_lock();
 822         chan = ust_registry_channel_find(session, key);
 823         if (!chan) {
 824                 rcu_read_unlock();
 825                 goto end;
 826         }
 827
 828         iter.iter.node = &chan->node.node;
 829         ret = lttng_ht_del(session->channels, &iter);
 830         assert(!ret);
 831         rcu_read_unlock();
 832         destroy_channel(chan, notif);
 833
 834 end:
 835         return;
 836 }
 837
 838 /*
 839  * Initialize registry with default values and set the newly allocated session
 840  * pointer to sessionp.
 841  *
 842  * Return 0 on success and sessionp is set or else return -1 and sessionp is
 843  * kept untouched.
 844  */
 845 int ust_registry_session_init(struct ust_registry_session **sessionp,
 846                 struct ust_app *app,
 847                 uint32_t bits_per_long,
 848                 uint32_t uint8_t_alignment,
 849                 uint32_t uint16_t_alignment,
 850                 uint32_t uint32_t_alignment,
 851                 uint32_t uint64_t_alignment,
 852                 uint32_t long_alignment,
 853                 int byte_order,
 854                 uint32_t major,
 855                 uint32_t minor,
 856                 const char *root_shm_path,
 857                 const char *shm_path,
 858                 uid_t euid,
 859                 gid_t egid)
 860 {
 861         int ret;
 862         struct ust_registry_session *session;
 863
 864         assert(sessionp);
 865
 866         session = zmalloc(sizeof(*session));
 867         if (!session) {
 868                 PERROR("zmalloc ust registry session");
 869                 goto error_alloc;
 870         }
 871
 872         pthread_mutex_init(&session->lock, NULL);
 873         session->bits_per_long = bits_per_long;
 874         session->uint8_t_alignment = uint8_t_alignment;
 875         session->uint16_t_alignment = uint16_t_alignment;
 876         session->uint32_t_alignment = uint32_t_alignment;
 877         session->uint64_t_alignment = uint64_t_alignment;
 878         session->long_alignment = long_alignment;
 879         session->byte_order = byte_order;
 880         session->metadata_fd = -1;
 881         session->uid = euid;
 882         session->gid = egid;
 883         session->next_enum_id = 0;
 884         session->major = major;
 885         session->minor = minor;
 886         strncpy(session->root_shm_path, root_shm_path,
 887                 sizeof(session->root_shm_path));
 888         session->root_shm_path[sizeof(session->root_shm_path) - 1] = '\0';
 889         if (shm_path[0]) {
 890                 strncpy(session->shm_path, shm_path,
 891                         sizeof(session->shm_path));
 892                 session->shm_path[sizeof(session->shm_path) - 1] = '\0';
 893                 strncpy(session->metadata_path, shm_path,
 894                         sizeof(session->metadata_path));
 895                 session->metadata_path[sizeof(session->metadata_path) - 1] = '\0';
 896                 strncat(session->metadata_path, "/metadata",
 897                         sizeof(session->metadata_path)
 898                                 - strlen(session->metadata_path) - 1);
 899         }
 900         if (session->shm_path[0]) {
 901                 ret = run_as_mkdir_recursive(session->shm_path,
 902                         S_IRWXU | S_IRWXG,
 903                         euid, egid);
 904                 if (ret) {
 905                         PERROR("run_as_mkdir_recursive");
 906                         goto error;
 907                 }
 908         }
 909         if (session->metadata_path[0]) {
 910                 /* Create metadata file */
 911                 ret = run_as_open(session->metadata_path,
 912                         O_WRONLY | O_CREAT | O_EXCL,
 913                         S_IRUSR | S_IWUSR, euid, egid);
 914                 if (ret < 0) {
 915                         PERROR("Opening metadata file");
 916                         goto error;
 917                 }
 918                 session->metadata_fd = ret;
 919         }
 920
 921         session->enums = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 922         if (!session->enums) {
 923                 ret = -ENOMEM;
 924                 goto error;
 925         }
 926         /* hash/match functions are specified at call site. */
 927         session->enums->match_fct = NULL;
 928         session->enums->hash_fct = NULL;
 929
 930         session->channels = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
 931         if (!session->channels) {
 932                 goto error;
 933         }
 934
 935         ret = lttng_uuid_generate(session->uuid);
 936         if (ret) {
 937                 ERR("Failed to generate UST uuid (errno = %d)", ret);
 938                 goto error;
 939         }
 940
 941         pthread_mutex_lock(&session->lock);
 942         ret = ust_metadata_session_statedump(session, app, major, minor);
 943         pthread_mutex_unlock(&session->lock);
 944         if (ret) {
 945                 ERR("Failed to generate session metadata (errno = %d)", ret);
 946                 goto error;
 947         }
 948
 949         *sessionp = session;
 950
 951         return 0;
 952
 953 error:
 954         ust_registry_session_destroy(session);
 955         free(session);
 956 error_alloc:
 957         return -1;
 958 }
 959
 960 /*
 961  * Destroy session registry. This does NOT free the given pointer since it
 962  * might get passed as a reference. The registry lock should NOT be acquired.
 963  */
 964 void ust_registry_session_destroy(struct ust_registry_session *reg)
 965 {
 966         int ret;
 967         struct lttng_ht_iter iter;
 968         struct ust_registry_channel *chan;
 969         struct ust_registry_enum *reg_enum;
 970
 971         if (!reg) {
 972                 return;
 973         }
 974
 975         /* On error, EBUSY can be returned if lock. Code flow error. */
 976         ret = pthread_mutex_destroy(&reg->lock);
 977         assert(!ret);
 978
 979         if (reg->channels) {
 980                 rcu_read_lock();
 981                 /* Destroy all event associated with this registry. */
 982                 cds_lfht_for_each_entry(reg->channels->ht, &iter.iter, chan,
 983                                 node.node) {
 984                         /* Delete the node from the ht and free it. */
 985                         ret = lttng_ht_del(reg->channels, &iter);
 986                         assert(!ret);
 987                         destroy_channel(chan, true);
 988                 }
 989                 rcu_read_unlock();
 990                 ht_cleanup_push(reg->channels);
 991         }
 992
 993         free(reg->metadata);
 994         if (reg->metadata_fd >= 0) {
 995                 ret = close(reg->metadata_fd);
 996                 if (ret) {
 997                         PERROR("close");
 998                 }
 999                 ret = run_as_unlink(reg->metadata_path,
1000                                 reg->uid, reg->gid);
1001                 if (ret) {
1002                         PERROR("unlink");
1003                 }
1004         }
1005         if (reg->root_shm_path[0]) {
1006                 /*
1007                  * Try deleting the directory hierarchy.
1008                  */
1009                 (void) run_as_rmdir_recursive(reg->root_shm_path,
1010                                 reg->uid, reg->gid);
1011         }
1012         /* Destroy the enum hash table */
1013         if (reg->enums) {
1014                 rcu_read_lock();
1015                 /* Destroy all enum entries associated with this registry. */
1016                 cds_lfht_for_each_entry(reg->enums->ht, &iter.iter, reg_enum,
1017                                 node.node) {
1018                         ust_registry_destroy_enum(reg, reg_enum);
1019                 }
1020                 rcu_read_unlock();
1021                 ht_cleanup_push(reg->enums);
1022         }
1023 }