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

   1 /*
   2  * Copyright (C) 2013 David Goulet <dgoulet@efficios.com>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-only
   5  *
   6  */
   7
   8 #define _LGPL_SOURCE
   9 #include <inttypes.h>
  10
  11 #include <common/common.hpp>
  12 #include <common/hashtable/utils.hpp>
  13 #include <lttng/lttng.h>
  14
  15 #include "ust-registry.hpp"
  16 #include "ust-app.hpp"
  17 #include "ust-field-utils.hpp"
  18 #include "utils.hpp"
  19 #include "lttng-sessiond.hpp"
  20 #include "notification-thread-commands.hpp"
  21
  22 /*
  23  * Hash table match function for event in the registry.
  24  */
  25 static int ht_match_event(struct cds_lfht_node *node, const void *_key)
  26 {
  27         const struct ust_registry_event *key;
  28         struct ust_registry_event *event;
  29
  30         LTTNG_ASSERT(node);
  31         LTTNG_ASSERT(_key);
  32
  33         event = caa_container_of(node, struct ust_registry_event, node.node);
  34         LTTNG_ASSERT(event);
  35         key = (ust_registry_event *) _key;
  36
  37         /* It has to be a perfect match. First, compare the event names. */
  38         if (strncmp(event->name, key->name, sizeof(event->name))) {
  39                 goto no_match;
  40         }
  41
  42         /* Compare log levels. */
  43         if (event->loglevel_value != key->loglevel_value) {
  44                 goto no_match;
  45         }
  46
  47         /* Compare the arrays of fields. */
  48         if (!match_lttng_ust_ctl_field_array(event->fields, event->nr_fields,
  49                         key->fields, key->nr_fields)) {
  50                 goto no_match;
  51         }
  52
  53         /* Compare model URI. */
  54         if (event->model_emf_uri != NULL && key->model_emf_uri == NULL) {
  55                 goto no_match;
  56         } else if(event->model_emf_uri == NULL && key->model_emf_uri != NULL) {
  57                 goto no_match;
  58         } else if (event->model_emf_uri != NULL && key->model_emf_uri != NULL) {
  59                 if (strcmp(event->model_emf_uri, key->model_emf_uri)) {
  60                         goto no_match;
  61                 }
  62         }
  63
  64         /* Match */
  65         return 1;
  66
  67 no_match:
  68         return 0;
  69 }
  70
  71 static unsigned long ht_hash_event(const void *_key, unsigned long seed)
  72 {
  73         uint64_t hashed_key;
  74         const struct ust_registry_event *key = (ust_registry_event *) _key;
  75
  76         LTTNG_ASSERT(key);
  77
  78         hashed_key = (uint64_t) hash_key_str(key->name, seed);
  79
  80         return hash_key_u64(&hashed_key, seed);
  81 }
  82
  83 static int compare_enums(const struct ust_registry_enum *reg_enum_a,
  84                 const struct ust_registry_enum *reg_enum_b)
  85 {
  86         int ret = 0;
  87         size_t i;
  88
  89         LTTNG_ASSERT(strcmp(reg_enum_a->name, reg_enum_b->name) == 0);
  90         if (reg_enum_a->nr_entries != reg_enum_b->nr_entries) {
  91                 ret = -1;
  92                 goto end;
  93         }
  94         for (i = 0; i < reg_enum_a->nr_entries; i++) {
  95                 const struct lttng_ust_ctl_enum_entry *entries_a, *entries_b;
  96
  97                 entries_a = &reg_enum_a->entries[i];
  98                 entries_b = &reg_enum_b->entries[i];
  99                 if (entries_a->start.value != entries_b->start.value) {
 100                         ret = -1;
 101                         goto end;
 102                 }
 103                 if (entries_a->end.value != entries_b->end.value) {
 104                         ret = -1;
 105                         goto end;
 106                 }
 107                 if (entries_a->start.signedness != entries_b->start.signedness) {
 108                         ret = -1;
 109                         goto end;
 110                 }
 111                 if (entries_a->end.signedness != entries_b->end.signedness) {
 112                         ret = -1;
 113                         goto end;
 114                 }
 115
 116                 if (strcmp(entries_a->string, entries_b->string)) {
 117                         ret = -1;
 118                         goto end;
 119                 }
 120         }
 121 end:
 122         return ret;
 123 }
 124
 125 /*
 126  * Hash table match function for enumerations in the session. Match is
 127  * performed on enumeration name, and confirmed by comparing the enum
 128  * entries.
 129  */
 130 static int ht_match_enum(struct cds_lfht_node *node, const void *_key)
 131 {
 132         struct ust_registry_enum *_enum;
 133         const struct ust_registry_enum *key;
 134
 135         LTTNG_ASSERT(node);
 136         LTTNG_ASSERT(_key);
 137
 138         _enum = caa_container_of(node, struct ust_registry_enum,
 139                         node.node);
 140         LTTNG_ASSERT(_enum);
 141         key = (ust_registry_enum *) _key;
 142
 143         if (strncmp(_enum->name, key->name, LTTNG_UST_ABI_SYM_NAME_LEN)) {
 144                 goto no_match;
 145         }
 146         if (compare_enums(_enum, key)) {
 147                 goto no_match;
 148         }
 149
 150         /* Match. */
 151         return 1;
 152
 153 no_match:
 154         return 0;
 155 }
 156
 157 /*
 158  * Hash table match function for enumerations in the session. Match is
 159  * performed by enumeration ID.
 160  */
 161 static int ht_match_enum_id(struct cds_lfht_node *node, const void *_key)
 162 {
 163         struct ust_registry_enum *_enum;
 164         const struct ust_registry_enum *key = (ust_registry_enum *) _key;
 165
 166         LTTNG_ASSERT(node);
 167         LTTNG_ASSERT(_key);
 168
 169         _enum = caa_container_of(node, struct ust_registry_enum, node.node);
 170         LTTNG_ASSERT(_enum);
 171
 172         if (_enum->id != key->id) {
 173                 goto no_match;
 174         }
 175
 176         /* Match. */
 177         return 1;
 178
 179 no_match:
 180         return 0;
 181 }
 182
 183 /*
 184  * Hash table hash function for enumerations in the session. The
 185  * enumeration name is used for hashing.
 186  */
 187 static unsigned long ht_hash_enum(void *_key, unsigned long seed)
 188 {
 189         struct ust_registry_enum *key = (ust_registry_enum *) _key;
 190
 191         LTTNG_ASSERT(key);
 192         return hash_key_str(key->name, seed);
 193 }
 194
 195 /*
 196  * Return negative value on error, 0 if OK.
 197  *
 198  * TODO: we could add stricter verification of more types to catch
 199  * errors in liblttng-ust implementation earlier than consumption by the
 200  * trace reader.
 201  */
 202 static
 203 int validate_event_field(struct lttng_ust_ctl_field *field,
 204                 const char *event_name,
 205                 struct ust_app *app)
 206 {
 207         int ret = 0;
 208
 209         switch(field->type.atype) {
 210         case lttng_ust_ctl_atype_integer:
 211         case lttng_ust_ctl_atype_enum:
 212         case lttng_ust_ctl_atype_array:
 213         case lttng_ust_ctl_atype_sequence:
 214         case lttng_ust_ctl_atype_string:
 215         case lttng_ust_ctl_atype_variant:
 216         case lttng_ust_ctl_atype_array_nestable:
 217         case lttng_ust_ctl_atype_sequence_nestable:
 218         case lttng_ust_ctl_atype_enum_nestable:
 219         case lttng_ust_ctl_atype_variant_nestable:
 220                 break;
 221         case lttng_ust_ctl_atype_struct:
 222                 if (field->type.u.legacy._struct.nr_fields != 0) {
 223                         WARN("Unsupported non-empty struct field.");
 224                         ret = -EINVAL;
 225                         goto end;
 226                 }
 227                 break;
 228         case lttng_ust_ctl_atype_struct_nestable:
 229                 if (field->type.u.struct_nestable.nr_fields != 0) {
 230                         WARN("Unsupported non-empty struct field.");
 231                         ret = -EINVAL;
 232                         goto end;
 233                 }
 234                 break;
 235
 236         case lttng_ust_ctl_atype_float:
 237                 switch (field->type.u._float.mant_dig) {
 238                 case 0:
 239                         WARN("UST application '%s' (pid: %d) has unknown float mantissa '%u' "
 240                                 "in field '%s', rejecting event '%s'",
 241                                 app->name, app->pid,
 242                                 field->type.u._float.mant_dig,
 243                                 field->name,
 244                                 event_name);
 245                         ret = -EINVAL;
 246                         goto end;
 247                 default:
 248                         break;
 249                 }
 250                 break;
 251
 252         default:
 253                 ret = -ENOENT;
 254                 goto end;
 255         }
 256 end:
 257         return ret;
 258 }
 259
 260 static
 261 int validate_event_fields(size_t nr_fields, struct lttng_ust_ctl_field *fields,
 262                 const char *event_name, struct ust_app *app)
 263 {
 264         unsigned int i;
 265
 266         for (i = 0; i < nr_fields; i++) {
 267                 if (validate_event_field(&fields[i], event_name, app) < 0)
 268                         return -EINVAL;
 269         }
 270         return 0;
 271 }
 272
 273 /*
 274  * Allocate event and initialize it. This does NOT set a valid event id from a
 275  * registry.
 276  */
 277 static struct ust_registry_event *alloc_event(int session_objd,
 278                 int channel_objd, char *name, char *sig, size_t nr_fields,
 279                 struct lttng_ust_ctl_field *fields, int loglevel_value,
 280                 char *model_emf_uri, struct ust_app *app)
 281 {
 282         struct ust_registry_event *event = NULL;
 283
 284         /*
 285          * Ensure that the field content is valid.
 286          */
 287         if (validate_event_fields(nr_fields, fields, name, app) < 0) {
 288                 return NULL;
 289         }
 290
 291         event = zmalloc<ust_registry_event>();
 292         if (!event) {
 293                 PERROR("zmalloc ust registry event");
 294                 goto error;
 295         }
 296
 297         event->session_objd = session_objd;
 298         event->channel_objd = channel_objd;
 299         /* Allocated by ustctl. */
 300         event->signature = sig;
 301         event->nr_fields = nr_fields;
 302         event->fields = fields;
 303         event->loglevel_value = loglevel_value;
 304         event->model_emf_uri = model_emf_uri;
 305         if (name) {
 306                 /* Copy event name and force NULL byte. */
 307                 strncpy(event->name, name, sizeof(event->name));
 308                 event->name[sizeof(event->name) - 1] = '\0';
 309         }
 310         cds_lfht_node_init(&event->node.node);
 311
 312 error:
 313         return event;
 314 }
 315
 316 /*
 317  * Free event data structure. This does NOT delete it from any hash table. It's
 318  * safe to pass a NULL pointer. This should be called inside a call RCU if the
 319  * event is previously deleted from a rcu hash table.
 320  */
 321 static void destroy_event(struct ust_registry_event *event)
 322 {
 323         if (!event) {
 324                 return;
 325         }
 326
 327         free(event->fields);
 328         free(event->model_emf_uri);
 329         free(event->signature);
 330         free(event);
 331 }
 332
 333 /*
 334  * Destroy event function call of the call RCU.
 335  */
 336 static void destroy_event_rcu(struct rcu_head *head)
 337 {
 338         struct lttng_ht_node_u64 *node =
 339                 caa_container_of(head, struct lttng_ht_node_u64, head);
 340         struct ust_registry_event *event =
 341                 caa_container_of(node, struct ust_registry_event, node);
 342
 343         destroy_event(event);
 344 }
 345
 346 /*
 347  * Find an event using the name and signature in the given registry. RCU read
 348  * side lock MUST be acquired before calling this function and as long as the
 349  * event reference is kept by the caller.
 350  *
 351  * On success, the event pointer is returned else NULL.
 352  */
 353 struct ust_registry_event *ust_registry_find_event(
 354                 struct ust_registry_channel *chan, char *name, char *sig)
 355 {
 356         struct lttng_ht_node_u64 *node;
 357         struct lttng_ht_iter iter;
 358         struct ust_registry_event *event = NULL;
 359         struct ust_registry_event key;
 360
 361         LTTNG_ASSERT(chan);
 362         LTTNG_ASSERT(name);
 363         LTTNG_ASSERT(sig);
 364         ASSERT_RCU_READ_LOCKED();
 365
 366         /* Setup key for the match function. */
 367         strncpy(key.name, name, sizeof(key.name));
 368         key.name[sizeof(key.name) - 1] = '\0';
 369         key.signature = sig;
 370
 371         cds_lfht_lookup(chan->events->ht, chan->events->hash_fct(&key, lttng_ht_seed),
 372                         chan->events->match_fct, &key, &iter.iter);
 373         node = lttng_ht_iter_get_node_u64(&iter);
 374         if (!node) {
 375                 goto end;
 376         }
 377         event = caa_container_of(node, struct ust_registry_event, node);
 378
 379 end:
 380         return event;
 381 }
 382
 383 /*
 384  * Create a ust_registry_event from the given parameters and add it to the
 385  * registry hash table. If event_id is valid, it is set with the newly created
 386  * event id.
 387  *
 388  * On success, return 0 else a negative value. The created event MUST be unique
 389  * so on duplicate entry -EINVAL is returned. On error, event_id is untouched.
 390  *
 391  * Should be called with session registry mutex held.
 392  */
 393 int ust_registry_create_event(struct ust_registry_session *session,
 394                 uint64_t chan_key, int session_objd, int channel_objd, char *name,
 395                 char *sig, size_t nr_fields, struct lttng_ust_ctl_field *fields,
 396                 int loglevel_value, char *model_emf_uri, int buffer_type,
 397                 uint32_t *event_id_p, struct ust_app *app)
 398 {
 399         int ret;
 400         uint32_t event_id;
 401         struct cds_lfht_node *nptr;
 402         struct ust_registry_event *event = NULL;
 403         struct ust_registry_channel *chan;
 404
 405         LTTNG_ASSERT(session);
 406         LTTNG_ASSERT(name);
 407         LTTNG_ASSERT(sig);
 408         LTTNG_ASSERT(event_id_p);
 409
 410         rcu_read_lock();
 411
 412         /*
 413          * This should not happen but since it comes from the UST tracer, an
 414          * external party, don't assert and simply validate values.
 415          */
 416         if (session_objd < 0 || channel_objd < 0) {
 417                 ret = -EINVAL;
 418                 goto error_free;
 419         }
 420
 421         chan = ust_registry_channel_find(session, chan_key);
 422         if (!chan) {
 423                 ret = -EINVAL;
 424                 goto error_free;
 425         }
 426
 427         /* Check if we've reached the maximum possible id. */
 428         if (ust_registry_is_max_id(chan->used_event_id)) {
 429                 ret = -ENOENT;
 430                 goto error_free;
 431         }
 432
 433         event = alloc_event(session_objd, channel_objd, name, sig, nr_fields,
 434                         fields, loglevel_value, model_emf_uri, app);
 435         if (!event) {
 436                 ret = -ENOMEM;
 437                 goto error_free;
 438         }
 439
 440         DBG3("UST registry creating event with event: %s, sig: %s, id: %u, "
 441                         "chan_objd: %u, sess_objd: %u, chan_id: %u", event->name,
 442                         event->signature, event->id, event->channel_objd,
 443                         event->session_objd, chan->chan_id);
 444
 445         /*
 446          * This is an add unique with a custom match function for event. The node
 447          * are matched using the event name and signature.
 448          */
 449         nptr = cds_lfht_add_unique(chan->events->ht, chan->events->hash_fct(event,
 450                                 lttng_ht_seed), chan->events->match_fct, event, &event->node.node);
 451         if (nptr != &event->node.node) {
 452                 if (buffer_type == LTTNG_BUFFER_PER_UID) {
 453                         /*
 454                          * This is normal, we just have to send the event id of the
 455                          * returned node and make sure we destroy the previously allocated
 456                          * event object.
 457                          */
 458                         destroy_event(event);
 459                         event = caa_container_of(nptr, struct ust_registry_event,
 460                                         node.node);
 461                         LTTNG_ASSERT(event);
 462                         event_id = event->id;
 463                 } else {
 464                         ERR("UST registry create event add unique failed for event: %s, "
 465                                         "sig: %s, id: %u, chan_objd: %u, sess_objd: %u",
 466                                         event->name, event->signature, event->id,
 467                                         event->channel_objd, event->session_objd);
 468                         ret = -EINVAL;
 469                         goto error_unlock;
 470                 }
 471         } else {
 472                 /* Request next event id if the node was successfully added. */
 473                 event_id = event->id = ust_registry_get_next_event_id(chan);
 474         }
 475
 476         *event_id_p = event_id;
 477
 478         if (!event->metadata_dumped) {
 479                 /* Append to metadata */
 480                 ret = ust_metadata_event_statedump(session, chan, event);
 481                 if (ret) {
 482                         ERR("Error appending event metadata (errno = %d)", ret);
 483                         rcu_read_unlock();
 484                         return ret;
 485                 }
 486         }
 487
 488         rcu_read_unlock();
 489         return 0;
 490
 491 error_free:
 492         free(sig);
 493         free(fields);
 494         free(model_emf_uri);
 495 error_unlock:
 496         rcu_read_unlock();
 497         destroy_event(event);
 498         return ret;
 499 }
 500
 501 /*
 502  * For a given event in a registry, delete the entry and destroy the event.
 503  * This MUST be called within a RCU read side lock section.
 504  */
 505 void ust_registry_destroy_event(struct ust_registry_channel *chan,
 506                 struct ust_registry_event *event)
 507 {
 508         int ret;
 509         struct lttng_ht_iter iter;
 510
 511         LTTNG_ASSERT(chan);
 512         LTTNG_ASSERT(event);
 513         ASSERT_RCU_READ_LOCKED();
 514
 515         /* Delete the node first. */
 516         iter.iter.node = &event->node.node;
 517         ret = lttng_ht_del(chan->events, &iter);
 518         LTTNG_ASSERT(!ret);
 519
 520         call_rcu(&event->node.head, destroy_event_rcu);
 521
 522         return;
 523 }
 524
 525 static void destroy_enum(struct ust_registry_enum *reg_enum)
 526 {
 527         if (!reg_enum) {
 528                 return;
 529         }
 530         free(reg_enum->entries);
 531         free(reg_enum);
 532 }
 533
 534 static void destroy_enum_rcu(struct rcu_head *head)
 535 {
 536         struct ust_registry_enum *reg_enum =
 537                 caa_container_of(head, struct ust_registry_enum, rcu_head);
 538
 539         destroy_enum(reg_enum);
 540 }
 541
 542 /*
 543  * Lookup enumeration by name and comparing enumeration entries.
 544  * Needs to be called from RCU read-side critical section.
 545  */
 546 static struct ust_registry_enum *ust_registry_lookup_enum(
 547                 struct ust_registry_session *session,
 548                 const struct ust_registry_enum *reg_enum_lookup)
 549 {
 550         struct ust_registry_enum *reg_enum = NULL;
 551         struct lttng_ht_node_str *node;
 552         struct lttng_ht_iter iter;
 553
 554         ASSERT_RCU_READ_LOCKED();
 555
 556         cds_lfht_lookup(session->enums->ht,
 557                         ht_hash_enum((void *) reg_enum_lookup, lttng_ht_seed),
 558                         ht_match_enum, reg_enum_lookup, &iter.iter);
 559         node = lttng_ht_iter_get_node_str(&iter);
 560         if (!node) {
 561                 goto end;
 562         }
 563         reg_enum = caa_container_of(node, struct ust_registry_enum, node);
 564 end:
 565         return reg_enum;
 566 }
 567
 568 /*
 569  * Lookup enumeration by enum ID.
 570  * Needs to be called from RCU read-side critical section.
 571  */
 572 struct ust_registry_enum *
 573         ust_registry_lookup_enum_by_id(struct ust_registry_session *session,
 574                 const char *enum_name, uint64_t enum_id)
 575 {
 576         struct ust_registry_enum *reg_enum = NULL;
 577         struct lttng_ht_node_str *node;
 578         struct lttng_ht_iter iter;
 579         struct ust_registry_enum reg_enum_lookup;
 580
 581         ASSERT_RCU_READ_LOCKED();
 582
 583         memset(&reg_enum_lookup, 0, sizeof(reg_enum_lookup));
 584         strncpy(reg_enum_lookup.name, enum_name, LTTNG_UST_ABI_SYM_NAME_LEN);
 585         reg_enum_lookup.name[LTTNG_UST_ABI_SYM_NAME_LEN - 1] = '\0';
 586         reg_enum_lookup.id = enum_id;
 587         cds_lfht_lookup(session->enums->ht,
 588                         ht_hash_enum((void *) &reg_enum_lookup, lttng_ht_seed),
 589                         ht_match_enum_id, &reg_enum_lookup, &iter.iter);
 590         node = lttng_ht_iter_get_node_str(&iter);
 591         if (!node) {
 592                 goto end;
 593         }
 594         reg_enum = caa_container_of(node, struct ust_registry_enum, node);
 595 end:
 596         return reg_enum;
 597 }
 598
 599 /*
 600  * Create a ust_registry_enum from the given parameters and add it to the
 601  * registry hash table, or find it if already there.
 602  *
 603  * On success, return 0 else a negative value.
 604  *
 605  * Should be called with session registry mutex held.
 606  *
 607  * We receive ownership of entries.
 608  */
 609 int ust_registry_create_or_find_enum(struct ust_registry_session *session,
 610                 int session_objd, char *enum_name,
 611                 struct lttng_ust_ctl_enum_entry *entries, size_t nr_entries,
 612                 uint64_t *enum_id)
 613 {
 614         int ret = 0;
 615         struct cds_lfht_node *nodep;
 616         struct ust_registry_enum *reg_enum = NULL, *old_reg_enum;
 617
 618         LTTNG_ASSERT(session);
 619         LTTNG_ASSERT(enum_name);
 620
 621         rcu_read_lock();
 622
 623         /*
 624          * This should not happen but since it comes from the UST tracer, an
 625          * external party, don't assert and simply validate values.
 626          */
 627         if (session_objd < 0) {
 628                 ret = -EINVAL;
 629                 goto end;
 630         }
 631
 632         /* Check if the enumeration was already dumped */
 633         reg_enum = zmalloc<ust_registry_enum>();
 634         if (!reg_enum) {
 635                 PERROR("zmalloc ust registry enumeration");
 636                 ret = -ENOMEM;
 637                 goto end;
 638         }
 639         strncpy(reg_enum->name, enum_name, LTTNG_UST_ABI_SYM_NAME_LEN);
 640         reg_enum->name[LTTNG_UST_ABI_SYM_NAME_LEN - 1] = '\0';
 641         /* entries will be owned by reg_enum. */
 642         reg_enum->entries = entries;
 643         reg_enum->nr_entries = nr_entries;
 644         entries = NULL;
 645
 646         old_reg_enum = ust_registry_lookup_enum(session, reg_enum);
 647         if (old_reg_enum) {
 648                 DBG("enum %s already in sess_objd: %u", enum_name, session_objd);
 649                 /* Fall through. Use prior enum. */
 650                 destroy_enum(reg_enum);
 651                 reg_enum = old_reg_enum;
 652         } else {
 653                 DBG("UST registry creating enum: %s, sess_objd: %u",
 654                                 enum_name, session_objd);
 655                 if (session->next_enum_id == -1ULL) {
 656                         ret = -EOVERFLOW;
 657                         destroy_enum(reg_enum);
 658                         goto end;
 659                 }
 660                 reg_enum->id = session->next_enum_id++;
 661                 cds_lfht_node_init(&reg_enum->node.node);
 662                 nodep = cds_lfht_add_unique(session->enums->ht,
 663                                 ht_hash_enum(reg_enum, lttng_ht_seed),
 664                                 ht_match_enum_id, reg_enum,
 665                                 &reg_enum->node.node);
 666                 LTTNG_ASSERT(nodep == &reg_enum->node.node);
 667         }
 668         DBG("UST registry reply with enum %s with id %" PRIu64 " in sess_objd: %u",
 669                         enum_name, reg_enum->id, session_objd);
 670         *enum_id = reg_enum->id;
 671 end:
 672         free(entries);
 673         rcu_read_unlock();
 674         return ret;
 675 }
 676
 677 /*
 678  * For a given enumeration in a registry, delete the entry and destroy
 679  * the enumeration.
 680  * This MUST be called within a RCU read side lock section.
 681  */
 682 static void ust_registry_destroy_enum(struct ust_registry_session *reg_session,
 683                 struct ust_registry_enum *reg_enum)
 684 {
 685         int ret;
 686         struct lttng_ht_iter iter;
 687
 688         LTTNG_ASSERT(reg_session);
 689         LTTNG_ASSERT(reg_enum);
 690         ASSERT_RCU_READ_LOCKED();
 691
 692         /* Delete the node first. */
 693         iter.iter.node = &reg_enum->node.node;
 694         ret = lttng_ht_del(reg_session->enums, &iter);
 695         LTTNG_ASSERT(!ret);
 696         call_rcu(&reg_enum->rcu_head, destroy_enum_rcu);
 697 }
 698
 699 static
 700 void destroy_channel_rcu(struct rcu_head *head)
 701 {
 702         struct ust_registry_channel *chan =
 703                 caa_container_of(head, struct ust_registry_channel, rcu_head);
 704
 705         if (chan->events) {
 706                 lttng_ht_destroy(chan->events);
 707         }
 708
 709         free(chan->ctx_fields);
 710         free(chan);
 711 }
 712
 713 /*
 714  * Destroy every element of the registry and free the memory. This does NOT
 715  * free the registry pointer since it might not have been allocated before so
 716  * it's the caller responsability.
 717  */
 718 static void destroy_channel(struct ust_registry_channel *chan, bool notif)
 719 {
 720         struct lttng_ht_iter iter;
 721         struct ust_registry_event *event;
 722         enum lttng_error_code cmd_ret;
 723
 724         LTTNG_ASSERT(chan);
 725
 726         if (notif) {
 727                 cmd_ret = notification_thread_command_remove_channel(
 728                                 the_notification_thread_handle,
 729                                 chan->consumer_key, LTTNG_DOMAIN_UST);
 730                 if (cmd_ret != LTTNG_OK) {
 731                         ERR("Failed to remove channel from notification thread");
 732                 }
 733         }
 734
 735         if (chan->events) {
 736                 rcu_read_lock();
 737                 /* Destroy all event associated with this registry. */
 738                 cds_lfht_for_each_entry(
 739                                 chan->events->ht, &iter.iter, event, node.node) {
 740                         /* Delete the node from the ht and free it. */
 741                         ust_registry_destroy_event(chan, event);
 742                 }
 743                 rcu_read_unlock();
 744         }
 745         call_rcu(&chan->rcu_head, destroy_channel_rcu);
 746 }
 747
 748 /*
 749  * Initialize registry with default values.
 750  */
 751 int ust_registry_channel_add(struct ust_registry_session *session,
 752                 uint64_t key)
 753 {
 754         int ret = 0;
 755         struct ust_registry_channel *chan;
 756
 757         LTTNG_ASSERT(session);
 758
 759         chan = zmalloc<ust_registry_channel>();
 760         if (!chan) {
 761                 PERROR("zmalloc ust registry channel");
 762                 ret = -ENOMEM;
 763                 goto error_alloc;
 764         }
 765
 766         chan->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 767         if (!chan->events) {
 768                 ret = -ENOMEM;
 769                 goto error;
 770         }
 771
 772         /* Set custom match function. */
 773         chan->events->match_fct = ht_match_event;
 774         chan->events->hash_fct = ht_hash_event;
 775
 776         /*
 777          * Assign a channel ID right now since the event notification comes
 778          * *before* the channel notify so the ID needs to be set at this point so
 779          * the metadata can be dumped for that event.
 780          */
 781         if (ust_registry_is_max_id(session->used_channel_id)) {
 782                 ret = -1;
 783                 goto error;
 784         }
 785         chan->chan_id = ust_registry_get_next_chan_id(session);
 786
 787         rcu_read_lock();
 788         lttng_ht_node_init_u64(&chan->node, key);
 789         lttng_ht_add_unique_u64(session->channels, &chan->node);
 790         rcu_read_unlock();
 791
 792         return 0;
 793
 794 error:
 795         destroy_channel(chan, false);
 796 error_alloc:
 797         return ret;
 798 }
 799
 800 /*
 801  * Find a channel in the given registry. RCU read side lock MUST be acquired
 802  * before calling this function and as long as the event reference is kept by
 803  * the caller.
 804  *
 805  * On success, the pointer is returned else NULL.
 806  */
 807 struct ust_registry_channel *ust_registry_channel_find(
 808                 struct ust_registry_session *session, uint64_t key)
 809 {
 810         struct lttng_ht_node_u64 *node;
 811         struct lttng_ht_iter iter;
 812         struct ust_registry_channel *chan = NULL;
 813
 814         LTTNG_ASSERT(session);
 815         LTTNG_ASSERT(session->channels);
 816         ASSERT_RCU_READ_LOCKED();
 817
 818         DBG3("UST registry channel finding key %" PRIu64, key);
 819
 820         lttng_ht_lookup(session->channels, &key, &iter);
 821         node = lttng_ht_iter_get_node_u64(&iter);
 822         if (!node) {
 823                 goto end;
 824         }
 825         chan = caa_container_of(node, struct ust_registry_channel, node);
 826
 827 end:
 828         return chan;
 829 }
 830
 831 /*
 832  * Remove channel using key from registry and free memory.
 833  */
 834 void ust_registry_channel_del_free(struct ust_registry_session *session,
 835                 uint64_t key, bool notif)
 836 {
 837         struct lttng_ht_iter iter;
 838         struct ust_registry_channel *chan;
 839         int ret;
 840
 841         LTTNG_ASSERT(session);
 842
 843         rcu_read_lock();
 844         chan = ust_registry_channel_find(session, key);
 845         if (!chan) {
 846                 rcu_read_unlock();
 847                 goto end;
 848         }
 849
 850         iter.iter.node = &chan->node.node;
 851         ret = lttng_ht_del(session->channels, &iter);
 852         LTTNG_ASSERT(!ret);
 853         rcu_read_unlock();
 854         destroy_channel(chan, notif);
 855
 856 end:
 857         return;
 858 }
 859
 860 /*
 861  * Initialize registry with default values and set the newly allocated session
 862  * pointer to sessionp.
 863  *
 864  * Return 0 on success and sessionp is set or else return -1 and sessionp is
 865  * kept untouched.
 866  */
 867 int ust_registry_session_init(struct ust_registry_session **sessionp,
 868                 struct ust_app *app,
 869                 uint32_t bits_per_long,
 870                 uint32_t uint8_t_alignment,
 871                 uint32_t uint16_t_alignment,
 872                 uint32_t uint32_t_alignment,
 873                 uint32_t uint64_t_alignment,
 874                 uint32_t long_alignment,
 875                 int byte_order,
 876                 uint32_t major,
 877                 uint32_t minor,
 878                 const char *root_shm_path,
 879                 const char *shm_path,
 880                 uid_t euid,
 881                 gid_t egid,
 882                 uint64_t tracing_id,
 883                 uid_t tracing_uid)
 884 {
 885         int ret;
 886         struct ust_registry_session *session;
 887
 888         LTTNG_ASSERT(sessionp);
 889
 890         session = zmalloc<ust_registry_session>();
 891         if (!session) {
 892                 PERROR("zmalloc ust registry session");
 893                 goto error_alloc;
 894         }
 895
 896         pthread_mutex_init(&session->lock, NULL);
 897         session->bits_per_long = bits_per_long;
 898         session->uint8_t_alignment = uint8_t_alignment;
 899         session->uint16_t_alignment = uint16_t_alignment;
 900         session->uint32_t_alignment = uint32_t_alignment;
 901         session->uint64_t_alignment = uint64_t_alignment;
 902         session->long_alignment = long_alignment;
 903         session->byte_order = byte_order;
 904         session->metadata_fd = -1;
 905         session->uid = euid;
 906         session->gid = egid;
 907         session->next_enum_id = 0;
 908         session->major = major;
 909         session->minor = minor;
 910         strncpy(session->root_shm_path, root_shm_path,
 911                 sizeof(session->root_shm_path));
 912         session->root_shm_path[sizeof(session->root_shm_path) - 1] = '\0';
 913         if (shm_path[0]) {
 914                 strncpy(session->shm_path, shm_path,
 915                         sizeof(session->shm_path));
 916                 session->shm_path[sizeof(session->shm_path) - 1] = '\0';
 917                 strncpy(session->metadata_path, shm_path,
 918                         sizeof(session->metadata_path));
 919                 session->metadata_path[sizeof(session->metadata_path) - 1] = '\0';
 920                 strncat(session->metadata_path, "/metadata",
 921                         sizeof(session->metadata_path)
 922                                 - strlen(session->metadata_path) - 1);
 923         }
 924         if (session->shm_path[0]) {
 925                 ret = run_as_mkdir_recursive(session->shm_path,
 926                         S_IRWXU | S_IRWXG,
 927                         euid, egid);
 928                 if (ret) {
 929                         PERROR("run_as_mkdir_recursive");
 930                         goto error;
 931                 }
 932         }
 933         if (session->metadata_path[0]) {
 934                 /* Create metadata file */
 935                 ret = run_as_open(session->metadata_path,
 936                         O_WRONLY | O_CREAT | O_EXCL,
 937                         S_IRUSR | S_IWUSR, euid, egid);
 938                 if (ret < 0) {
 939                         PERROR("Opening metadata file");
 940                         goto error;
 941                 }
 942                 session->metadata_fd = ret;
 943         }
 944
 945         session->enums = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 946         if (!session->enums) {
 947                 ERR("Failed to create enums hash table");
 948                 goto error;
 949         }
 950         /* hash/match functions are specified at call site. */
 951         session->enums->match_fct = NULL;
 952         session->enums->hash_fct = NULL;
 953
 954         session->channels = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
 955         if (!session->channels) {
 956                 goto error;
 957         }
 958
 959         ret = lttng_uuid_generate(session->uuid);
 960         if (ret) {
 961                 ERR("Failed to generate UST uuid (errno = %d)", ret);
 962                 goto error;
 963         }
 964
 965         session->tracing_id = tracing_id;
 966         session->tracing_uid = tracing_uid;
 967
 968         pthread_mutex_lock(&session->lock);
 969         ret = ust_metadata_session_statedump(session, app, major, minor);
 970         pthread_mutex_unlock(&session->lock);
 971         if (ret) {
 972                 ERR("Failed to generate session metadata (errno = %d)", ret);
 973                 goto error;
 974         }
 975
 976         *sessionp = session;
 977
 978         return 0;
 979
 980 error:
 981         ust_registry_session_destroy(session);
 982         free(session);
 983 error_alloc:
 984         return -1;
 985 }
 986
 987 /*
 988  * Destroy session registry. This does NOT free the given pointer since it
 989  * might get passed as a reference. The registry lock should NOT be acquired.
 990  */
 991 void ust_registry_session_destroy(struct ust_registry_session *reg)
 992 {
 993         int ret;
 994         struct lttng_ht_iter iter;
 995         struct ust_registry_channel *chan;
 996         struct ust_registry_enum *reg_enum;
 997
 998         if (!reg) {
 999                 return;
1000         }
1001
1002         /* On error, EBUSY can be returned if lock. Code flow error. */
1003         ret = pthread_mutex_destroy(&reg->lock);
1004         LTTNG_ASSERT(!ret);
1005
1006         if (reg->channels) {
1007                 rcu_read_lock();
1008                 /* Destroy all event associated with this registry. */
1009                 cds_lfht_for_each_entry(reg->channels->ht, &iter.iter, chan,
1010                                 node.node) {
1011                         /* Delete the node from the ht and free it. */
1012                         ret = lttng_ht_del(reg->channels, &iter);
1013                         LTTNG_ASSERT(!ret);
1014                         destroy_channel(chan, true);
1015                 }
1016                 rcu_read_unlock();
1017                 lttng_ht_destroy(reg->channels);
1018         }
1019
1020         free(reg->metadata);
1021         if (reg->metadata_fd >= 0) {
1022                 ret = close(reg->metadata_fd);
1023                 if (ret) {
1024                         PERROR("close");
1025                 }
1026                 ret = run_as_unlink(reg->metadata_path,
1027                                 reg->uid, reg->gid);
1028                 if (ret) {
1029                         PERROR("unlink");
1030                 }
1031         }
1032         if (reg->root_shm_path[0]) {
1033                 /*
1034                  * Try deleting the directory hierarchy.
1035                  */
1036                 (void) run_as_rmdir_recursive(reg->root_shm_path,
1037                                 reg->uid, reg->gid,
1038                                 LTTNG_DIRECTORY_HANDLE_SKIP_NON_EMPTY_FLAG);
1039         }
1040         /* Destroy the enum hash table */
1041         if (reg->enums) {
1042                 rcu_read_lock();
1043                 /* Destroy all enum entries associated with this registry. */
1044                 cds_lfht_for_each_entry(reg->enums->ht, &iter.iter, reg_enum,
1045                                 node.node) {
1046                         ust_registry_destroy_enum(reg, reg_enum);
1047                 }
1048                 rcu_read_unlock();
1049                 lttng_ht_destroy(reg->enums);
1050         }
1051 }