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

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