src/bin/lttng-sessiond/agent.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 _GNU_SOURCE
  19 #define _LGPL_SOURCE
  20 #include <assert.h>
  21 #include <urcu/uatomic.h>
  22
  23 #include <common/common.h>
  24 #include <common/sessiond-comm/agent.h>
  25
  26 #include <common/compat/endian.h>
  27
  28 #include "agent.h"
  29 #include "ust-app.h"
  30 #include "utils.h"
  31
  32 /*
  33  * Match function for the events hash table lookup by name.
  34  */
  35 static int ht_match_event_by_name(struct cds_lfht_node *node,
  36                 const void *_key)
  37 {
  38         struct agent_event *event;
  39         const struct agent_ht_key *key;
  40
  41         assert(node);
  42         assert(_key);
  43
  44         event = caa_container_of(node, struct agent_event, node.node);
  45         key = _key;
  46
  47         /* Match 1 elements of the key: name. */
  48
  49         /* Event name */
  50         if (strncmp(event->name, key->name, sizeof(event->name)) != 0) {
  51                 goto no_match;
  52         }
  53         /* Match. */
  54         return 1;
  55
  56 no_match:
  57         return 0;
  58 }
  59
  60 /*
  61  * Match function for the events hash table lookup by name and loglevel.
  62  */
  63 static int ht_match_event(struct cds_lfht_node *node,
  64                 const void *_key)
  65 {
  66         struct agent_event *event;
  67         const struct agent_ht_key *key;
  68
  69         assert(node);
  70         assert(_key);
  71
  72         event = caa_container_of(node, struct agent_event, node.node);
  73         key = _key;
  74
  75         /* Match 2 elements of the key: name and loglevel. */
  76
  77         /* Event name */
  78         if (strncmp(event->name, key->name, sizeof(event->name)) != 0) {
  79                 goto no_match;
  80         }
  81
  82         if (event->loglevel_value != key->loglevel_value) {
  83                 if (event->loglevel_type == LTTNG_EVENT_LOGLEVEL_ALL &&
  84                                 key->loglevel_value == 0 &&
  85                                 event->loglevel_value == -1) {
  86                         goto match;
  87                 }
  88                 goto no_match;
  89         }
  90 match:
  91         return 1;
  92
  93 no_match:
  94         return 0;
  95 }
  96
  97 /*
  98  * Add unique agent event based on the event name and loglevel.
  99  */
 100 static void add_unique_agent_event(struct lttng_ht *ht,
 101                 struct agent_event *event)
 102 {
 103         struct cds_lfht_node *node_ptr;
 104         struct agent_ht_key key;
 105
 106         assert(ht);
 107         assert(ht->ht);
 108         assert(event);
 109
 110         key.name = event->name;
 111         key.loglevel_value = event->loglevel_value;
 112
 113         node_ptr = cds_lfht_add_unique(ht->ht,
 114                         ht->hash_fct(event->node.key, lttng_ht_seed),
 115                         ht_match_event, &key, &event->node.node);
 116         assert(node_ptr == &event->node.node);
 117 }
 118
 119 /*
 120  * URCU delayed agent event reclaim.
 121  */
 122 static void destroy_event_agent_rcu(struct rcu_head *head)
 123 {
 124         struct lttng_ht_node_str *node =
 125                 caa_container_of(head, struct lttng_ht_node_str, head);
 126         struct agent_event *event =
 127                 caa_container_of(node, struct agent_event, node);
 128
 129         agent_destroy_event(event);
 130 }
 131
 132 /*
 133  * URCU delayed agent app reclaim.
 134  */
 135 static void destroy_app_agent_rcu(struct rcu_head *head)
 136 {
 137         struct lttng_ht_node_ulong *node =
 138                 caa_container_of(head, struct lttng_ht_node_ulong, head);
 139         struct agent_app *app =
 140                 caa_container_of(node, struct agent_app, node);
 141
 142         free(app);
 143 }
 144
 145 /*
 146  * Communication with the agent. Send the message header to the given socket in
 147  * big endian.
 148  *
 149  * Return 0 on success or else a negative errno message of sendmsg() op.
 150  */
 151 static int send_header(struct lttcomm_sock *sock, uint64_t data_size,
 152                 uint32_t cmd, uint32_t cmd_version)
 153 {
 154         int ret;
 155         ssize_t size;
 156         struct lttcomm_agent_hdr msg;
 157
 158         assert(sock);
 159
 160         memset(&msg, 0, sizeof(msg));
 161         msg.data_size = htobe64(data_size);
 162         msg.cmd = htobe32(cmd);
 163         msg.cmd_version = htobe32(cmd_version);
 164
 165         size = sock->ops->sendmsg(sock, &msg, sizeof(msg), 0);
 166         if (size < sizeof(msg)) {
 167                 ret = -errno;
 168                 goto error;
 169         }
 170         ret = 0;
 171
 172 error:
 173         return ret;
 174 }
 175
 176 /*
 177  * Communication call with the agent. Send the payload to the given socket. The
 178  * header MUST be sent prior to this call.
 179  *
 180  * Return 0 on success or else a negative errno value of sendmsg() op.
 181  */
 182 static int send_payload(struct lttcomm_sock *sock, void *data,
 183                 size_t size)
 184 {
 185         int ret;
 186         ssize_t len;
 187
 188         assert(sock);
 189         assert(data);
 190
 191         len = sock->ops->sendmsg(sock, data, size, 0);
 192         if (len < size) {
 193                 ret = -errno;
 194                 goto error;
 195         }
 196         ret = 0;
 197
 198 error:
 199         return ret;
 200 }
 201
 202 /*
 203  * Communication call with the agent. Receive reply from the agent using the
 204  * given socket.
 205  *
 206  * Return 0 on success or else a negative errno value from recvmsg() op.
 207  */
 208 static int recv_reply(struct lttcomm_sock *sock, void *buf, size_t size)
 209 {
 210         int ret;
 211         ssize_t len;
 212
 213         assert(sock);
 214         assert(buf);
 215
 216         len = sock->ops->recvmsg(sock, buf, size, 0);
 217         if (len < size) {
 218                 ret = -errno;
 219                 goto error;
 220         }
 221         ret = 0;
 222
 223 error:
 224         return ret;
 225 }
 226
 227 /*
 228  * Internal event listing for a given app. Populate events.
 229  *
 230  * Return number of element in the list or else a negative LTTNG_ERR* code.
 231  * On success, the caller is responsible for freeing the memory
 232  * allocated for "events".
 233  */
 234 static ssize_t list_events(struct agent_app *app, struct lttng_event **events)
 235 {
 236         int ret, i, len = 0, offset = 0;
 237         uint32_t nb_event;
 238         size_t data_size;
 239         struct lttng_event *tmp_events = NULL;
 240         struct lttcomm_agent_list_reply *reply = NULL;
 241         struct lttcomm_agent_list_reply_hdr reply_hdr;
 242
 243         assert(app);
 244         assert(app->sock);
 245         assert(events);
 246
 247         DBG2("Agent listing events for app pid: %d and socket %d", app->pid,
 248                         app->sock->fd);
 249
 250         ret = send_header(app->sock, 0, AGENT_CMD_LIST, 0);
 251         if (ret < 0) {
 252                 goto error_io;
 253         }
 254
 255         /* Get list header so we know how much we'll receive. */
 256         ret = recv_reply(app->sock, &reply_hdr, sizeof(reply_hdr));
 257         if (ret < 0) {
 258                 goto error_io;
 259         }
 260
 261         switch (be32toh(reply_hdr.ret_code)) {
 262         case AGENT_RET_CODE_SUCCESS:
 263                 data_size = be32toh(reply_hdr.data_size) + sizeof(*reply);
 264                 break;
 265         default:
 266                 ERR("Agent returned an unknown code: %" PRIu32,
 267                                 be32toh(reply_hdr.ret_code));
 268                 ret = LTTNG_ERR_FATAL;
 269                 goto error;
 270         }
 271
 272         reply = zmalloc(data_size);
 273         if (!reply) {
 274                 ret = LTTNG_ERR_NOMEM;
 275                 goto error;
 276         }
 277
 278         /* Get the list with the appropriate data size. */
 279         ret = recv_reply(app->sock, reply, data_size);
 280         if (ret < 0) {
 281                 goto error_io;
 282         }
 283
 284         nb_event = be32toh(reply->nb_event);
 285         tmp_events = zmalloc(sizeof(*tmp_events) * nb_event);
 286         if (!tmp_events) {
 287                 ret = LTTNG_ERR_NOMEM;
 288                 goto error;
 289         }
 290
 291         for (i = 0; i < nb_event; i++) {
 292                 offset += len;
 293                 strncpy(tmp_events[i].name, reply->payload + offset,
 294                                 sizeof(tmp_events[i].name));
 295                 tmp_events[i].pid = app->pid;
 296                 tmp_events[i].enabled = -1;
 297                 len = strlen(reply->payload + offset) + 1;
 298         }
 299
 300         *events = tmp_events;
 301
 302         free(reply);
 303         return nb_event;
 304
 305 error_io:
 306         ret = LTTNG_ERR_UST_LIST_FAIL;
 307 error:
 308         free(reply);
 309         free(tmp_events);
 310         return -ret;
 311
 312 }
 313
 314 /*
 315  * Internal enable agent event on a agent application. This function
 316  * communicates with the agent to enable a given event.
 317  *
 318  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 319  */
 320 static int enable_event(struct agent_app *app, struct agent_event *event)
 321 {
 322         int ret;
 323         uint64_t data_size;
 324         struct lttcomm_agent_enable msg;
 325         struct lttcomm_agent_generic_reply reply;
 326
 327         assert(app);
 328         assert(app->sock);
 329         assert(event);
 330
 331         DBG2("Agent enabling event %s for app pid: %d and socket %d", event->name,
 332                         app->pid, app->sock->fd);
 333
 334         data_size = sizeof(msg);
 335
 336         ret = send_header(app->sock, data_size, AGENT_CMD_ENABLE, 0);
 337         if (ret < 0) {
 338                 goto error_io;
 339         }
 340
 341         memset(&msg, 0, sizeof(msg));
 342         msg.loglevel_value = event->loglevel_value;
 343         msg.loglevel_type = event->loglevel_type;
 344         strncpy(msg.name, event->name, sizeof(msg.name));
 345         ret = send_payload(app->sock, &msg, sizeof(msg));
 346         if (ret < 0) {
 347                 goto error_io;
 348         }
 349
 350         ret = recv_reply(app->sock, &reply, sizeof(reply));
 351         if (ret < 0) {
 352                 goto error_io;
 353         }
 354
 355         switch (be32toh(reply.ret_code)) {
 356         case AGENT_RET_CODE_SUCCESS:
 357                 break;
 358         case AGENT_RET_CODE_UNKNOWN_NAME:
 359                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 360                 goto error;
 361         default:
 362                 ERR("Agent returned an unknown code: %" PRIu32,
 363                                 be32toh(reply.ret_code));
 364                 ret = LTTNG_ERR_FATAL;
 365                 goto error;
 366         }
 367
 368         return LTTNG_OK;
 369
 370 error_io:
 371         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 372 error:
 373         return ret;
 374 }
 375
 376 /*
 377  * Internal disable agent event call on a agent application. This function
 378  * communicates with the agent to disable a given event.
 379  *
 380  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 381  */
 382 static int disable_event(struct agent_app *app, struct agent_event *event)
 383 {
 384         int ret;
 385         uint64_t data_size;
 386         struct lttcomm_agent_disable msg;
 387         struct lttcomm_agent_generic_reply reply;
 388
 389         assert(app);
 390         assert(app->sock);
 391         assert(event);
 392
 393         DBG2("Agent disabling event %s for app pid: %d and socket %d", event->name,
 394                         app->pid, app->sock->fd);
 395
 396         data_size = sizeof(msg);
 397
 398         ret = send_header(app->sock, data_size, AGENT_CMD_DISABLE, 0);
 399         if (ret < 0) {
 400                 goto error_io;
 401         }
 402
 403         memset(&msg, 0, sizeof(msg));
 404         strncpy(msg.name, event->name, sizeof(msg.name));
 405         ret = send_payload(app->sock, &msg, sizeof(msg));
 406         if (ret < 0) {
 407                 goto error_io;
 408         }
 409
 410         ret = recv_reply(app->sock, &reply, sizeof(reply));
 411         if (ret < 0) {
 412                 goto error_io;
 413         }
 414
 415         switch (be32toh(reply.ret_code)) {
 416         case AGENT_RET_CODE_SUCCESS:
 417                 break;
 418         case AGENT_RET_CODE_UNKNOWN_NAME:
 419                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 420                 goto error;
 421         default:
 422                 ERR("Agent returned an unknown code: %" PRIu32,
 423                                 be32toh(reply.ret_code));
 424                 ret = LTTNG_ERR_FATAL;
 425                 goto error;
 426         }
 427
 428         return LTTNG_OK;
 429
 430 error_io:
 431         ret = LTTNG_ERR_UST_DISABLE_FAIL;
 432 error:
 433         return ret;
 434 }
 435
 436 /*
 437  * Send back the registration DONE command to a given agent application.
 438  *
 439  * Return 0 on success or else a negative value.
 440  */
 441 int agent_send_registration_done(struct agent_app *app)
 442 {
 443         assert(app);
 444         assert(app->sock);
 445
 446         DBG("Agent sending registration done to app socket %d", app->sock->fd);
 447
 448         return send_header(app->sock, 0, AGENT_CMD_REG_DONE, 0);
 449 }
 450
 451 /*
 452  * Enable agent event on every agent applications registered with the session
 453  * daemon.
 454  *
 455  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 456  */
 457 int agent_enable_event(struct agent_event *event,
 458                 enum lttng_domain_type domain)
 459 {
 460         int ret;
 461         struct agent_app *app;
 462         struct lttng_ht_iter iter;
 463
 464         assert(event);
 465
 466         rcu_read_lock();
 467
 468         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 469                         node.node) {
 470                 if (app->domain != domain) {
 471                         continue;
 472                 }
 473
 474                 /* Enable event on agent application through TCP socket. */
 475                 ret = enable_event(app, event);
 476                 if (ret != LTTNG_OK) {
 477                         goto error;
 478                 }
 479         }
 480
 481         event->enabled = 1;
 482         ret = LTTNG_OK;
 483
 484 error:
 485         rcu_read_unlock();
 486         return ret;
 487 }
 488
 489 /*
 490  * Disable agent event on every agent applications registered with the session
 491  * daemon.
 492  *
 493  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 494  */
 495 int agent_disable_event(struct agent_event *event,
 496                 enum lttng_domain_type domain)
 497 {
 498         int ret = LTTNG_OK;
 499         struct agent_app *app;
 500         struct lttng_ht_iter iter;
 501
 502         assert(event);
 503         if (!event->enabled) {
 504                 goto end;
 505         }
 506
 507         rcu_read_lock();
 508
 509         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 510                         node.node) {
 511                 if (app->domain != domain) {
 512                         continue;
 513                 }
 514
 515                 /* Enable event on agent application through TCP socket. */
 516                 ret = disable_event(app, event);
 517                 if (ret != LTTNG_OK) {
 518                         goto error;
 519                 }
 520         }
 521
 522         event->enabled = 0;
 523
 524 error:
 525         rcu_read_unlock();
 526 end:
 527         return ret;
 528 }
 529
 530 /*
 531  * Ask every agent for the list of possible event. Events is allocated with the
 532  * events of every agent application.
 533  *
 534  * Return the number of events or else a negative value.
 535  */
 536 int agent_list_events(struct lttng_event **events,
 537                 enum lttng_domain_type domain)
 538 {
 539         int ret;
 540         size_t nbmem, count = 0;
 541         struct agent_app *app;
 542         struct lttng_event *tmp_events = NULL;
 543         struct lttng_ht_iter iter;
 544
 545         assert(events);
 546
 547         DBG2("Agent listing events for domain %d", domain);
 548
 549         nbmem = UST_APP_EVENT_LIST_SIZE;
 550         tmp_events = zmalloc(nbmem * sizeof(*tmp_events));
 551         if (!tmp_events) {
 552                 PERROR("zmalloc agent list events");
 553                 ret = -ENOMEM;
 554                 goto error;
 555         }
 556
 557         rcu_read_lock();
 558         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 559                         node.node) {
 560                 ssize_t nb_ev;
 561                 struct lttng_event *agent_events;
 562
 563                 /* Skip domain not asked by the list. */
 564                 if (app->domain != domain) {
 565                         continue;
 566                 }
 567
 568                 nb_ev = list_events(app, &agent_events);
 569                 if (nb_ev < 0) {
 570                         ret = nb_ev;
 571                         goto error_unlock;
 572                 }
 573
 574                 if (count + nb_ev > nbmem) {
 575                         /* In case the realloc fails, we free the memory */
 576                         struct lttng_event *new_tmp_events;
 577                         size_t new_nbmem;
 578
 579                         new_nbmem = max_t(size_t, count + nb_ev, nbmem << 1);
 580                         DBG2("Reallocating agent event list from %zu to %zu entries",
 581                                         nbmem, new_nbmem);
 582                         new_tmp_events = realloc(tmp_events,
 583                                 new_nbmem * sizeof(*new_tmp_events));
 584                         if (!new_tmp_events) {
 585                                 PERROR("realloc agent events");
 586                                 ret = -ENOMEM;
 587                                 free(agent_events);
 588                                 goto error_unlock;
 589                         }
 590                         /* Zero the new memory */
 591                         memset(new_tmp_events + nbmem, 0,
 592                                 (new_nbmem - nbmem) * sizeof(*new_tmp_events));
 593                         nbmem = new_nbmem;
 594                         tmp_events = new_tmp_events;
 595                 }
 596                 memcpy(tmp_events + count, agent_events,
 597                         nb_ev * sizeof(*tmp_events));
 598                 free(agent_events);
 599                 count += nb_ev;
 600         }
 601         rcu_read_unlock();
 602
 603         ret = count;
 604         *events = tmp_events;
 605         return ret;
 606
 607 error_unlock:
 608         rcu_read_unlock();
 609 error:
 610         free(tmp_events);
 611         return ret;
 612 }
 613
 614 /*
 615  * Create a agent app object using the given PID.
 616  *
 617  * Return newly allocated object or else NULL on error.
 618  */
 619 struct agent_app *agent_create_app(pid_t pid, enum lttng_domain_type domain,
 620                 struct lttcomm_sock *sock)
 621 {
 622         struct agent_app *app;
 623
 624         assert(sock);
 625
 626         app = zmalloc(sizeof(*app));
 627         if (!app) {
 628                 PERROR("zmalloc agent create");
 629                 goto error;
 630         }
 631
 632         app->pid = pid;
 633         app->domain = domain;
 634         app->sock = sock;
 635         lttng_ht_node_init_ulong(&app->node, (unsigned long) app->sock->fd);
 636
 637 error:
 638         return app;
 639 }
 640
 641 /*
 642  * Lookup agent app by socket in the global hash table.
 643  *
 644  * RCU read side lock MUST be acquired.
 645  *
 646  * Return object if found else NULL.
 647  */
 648 struct agent_app *agent_find_app_by_sock(int sock)
 649 {
 650         struct lttng_ht_node_ulong *node;
 651         struct lttng_ht_iter iter;
 652         struct agent_app *app;
 653
 654         assert(sock >= 0);
 655
 656         lttng_ht_lookup(agent_apps_ht_by_sock, (void *)((unsigned long) sock), &iter);
 657         node = lttng_ht_iter_get_node_ulong(&iter);
 658         if (node == NULL) {
 659                 goto error;
 660         }
 661         app = caa_container_of(node, struct agent_app, node);
 662
 663         DBG3("Agent app pid %d found by sock %d.", app->pid, sock);
 664         return app;
 665
 666 error:
 667         DBG3("Agent app NOT found by sock %d.", sock);
 668         return NULL;
 669 }
 670
 671 /*
 672  * Add agent application object to the global hash table.
 673  */
 674 void agent_add_app(struct agent_app *app)
 675 {
 676         assert(app);
 677
 678         DBG3("Agent adding app sock: %d and pid: %d to ht", app->sock->fd, app->pid);
 679
 680         rcu_read_lock();
 681         lttng_ht_add_unique_ulong(agent_apps_ht_by_sock, &app->node);
 682         rcu_read_unlock();
 683 }
 684
 685 /*
 686  * Delete agent application from the global hash table.
 687  *
 688  * rcu_read_lock() must be held by the caller.
 689  */
 690 void agent_delete_app(struct agent_app *app)
 691 {
 692         int ret;
 693         struct lttng_ht_iter iter;
 694
 695         assert(app);
 696
 697         DBG3("Agent deleting app pid: %d and sock: %d", app->pid, app->sock->fd);
 698
 699         iter.iter.node = &app->node.node;
 700         ret = lttng_ht_del(agent_apps_ht_by_sock, &iter);
 701         assert(!ret);
 702 }
 703
 704 /*
 705  * Destroy a agent application object by detaching it from its corresponding
 706  * UST app if one is connected by closing the socket. Finally, perform a
 707  * delayed memory reclaim.
 708  */
 709 void agent_destroy_app(struct agent_app *app)
 710 {
 711         assert(app);
 712
 713         if (app->sock) {
 714                 app->sock->ops->close(app->sock);
 715                 lttcomm_destroy_sock(app->sock);
 716         }
 717
 718         call_rcu(&app->node.head, destroy_app_agent_rcu);
 719 }
 720
 721 /*
 722  * Initialize an already allocated agent object.
 723  *
 724  * Return 0 on success or else a negative errno value.
 725  */
 726 int agent_init(struct agent *agt)
 727 {
 728         int ret;
 729
 730         assert(agt);
 731
 732         agt->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 733         if (!agt->events) {
 734                 ret = -ENOMEM;
 735                 goto error;
 736         }
 737         lttng_ht_node_init_u64(&agt->node, agt->domain);
 738
 739         return 0;
 740
 741 error:
 742         return ret;
 743 }
 744
 745 /*
 746  * Add agent object to the given hash table.
 747  */
 748 void agent_add(struct agent *agt, struct lttng_ht *ht)
 749 {
 750         assert(agt);
 751         assert(ht);
 752
 753         DBG3("Agent adding from domain %d", agt->domain);
 754
 755         rcu_read_lock();
 756         lttng_ht_add_unique_u64(ht, &agt->node);
 757         rcu_read_unlock();
 758 }
 759
 760 /*
 761  * Create an agent object for the given domain.
 762  *
 763  * Return the allocated agent or NULL on error.
 764  */
 765 struct agent *agent_create(enum lttng_domain_type domain)
 766 {
 767         int ret;
 768         struct agent *agt;
 769
 770         agt = zmalloc(sizeof(*agt));
 771         if (!agt) {
 772                 goto error;
 773         }
 774         agt->domain = domain;
 775
 776         ret = agent_init(agt);
 777         if (ret < 0) {
 778                 free(agt);
 779                 agt = NULL;
 780                 goto error;
 781         }
 782
 783 error:
 784         return agt;
 785 }
 786
 787 /*
 788  * Create a newly allocated agent event data structure.
 789  * Ownership of filter_expression is taken.
 790  *
 791  * Return a new object else NULL on error.
 792  */
 793 struct agent_event *agent_create_event(const char *name,
 794                 int loglevel_value, enum lttng_loglevel_type loglevel_type,
 795                 struct lttng_filter_bytecode *filter, char *filter_expression)
 796 {
 797         struct agent_event *event = NULL;
 798
 799         DBG3("Agent create new event with name %s", name);
 800
 801         if (!name) {
 802                 ERR("Failed to create agent event; no name provided.");
 803                 goto error;
 804         }
 805
 806         event = zmalloc(sizeof(*event));
 807         if (!event) {
 808                 goto error;
 809         }
 810
 811         strncpy(event->name, name, sizeof(event->name));
 812         event->name[sizeof(event->name) - 1] = '\0';
 813         lttng_ht_node_init_str(&event->node, event->name);
 814
 815         event->loglevel_value = loglevel_value;
 816         event->loglevel_type = loglevel_type;
 817         event->filter = filter;
 818         event->filter_expression = filter_expression;
 819 error:
 820         return event;
 821 }
 822
 823 /*
 824  * Unique add of a agent event to an agent object.
 825  */
 826 void agent_add_event(struct agent_event *event, struct agent *agt)
 827 {
 828         assert(event);
 829         assert(agt);
 830         assert(agt->events);
 831
 832         DBG3("Agent adding event %s", event->name);
 833
 834         rcu_read_lock();
 835         add_unique_agent_event(agt->events, event);
 836         rcu_read_unlock();
 837         agt->being_used = 1;
 838 }
 839
 840 /*
 841  * Find a agent event in the given agent using name.
 842  *
 843  * RCU read side lock MUST be acquired.
 844  *
 845  * Return object if found else NULL.
 846  */
 847 struct agent_event *agent_find_event_by_name(const char *name,
 848                 struct agent *agt)
 849 {
 850         struct lttng_ht_node_str *node;
 851         struct lttng_ht_iter iter;
 852         struct lttng_ht *ht;
 853         struct agent_ht_key key;
 854
 855         assert(name);
 856         assert(agt);
 857         assert(agt->events);
 858
 859         ht = agt->events;
 860         key.name = name;
 861
 862         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 863                         ht_match_event_by_name, &key, &iter.iter);
 864         node = lttng_ht_iter_get_node_str(&iter);
 865         if (node == NULL) {
 866                 goto error;
 867         }
 868
 869         DBG3("Agent event found %s by name.", name);
 870         return caa_container_of(node, struct agent_event, node);
 871
 872 error:
 873         DBG3("Agent NOT found by name %s.", name);
 874         return NULL;
 875 }
 876
 877 /*
 878  * Find a agent event in the given agent using name and loglevel.
 879  *
 880  * RCU read side lock MUST be acquired.
 881  *
 882  * Return object if found else NULL.
 883  */
 884 struct agent_event *agent_find_event(const char *name, int loglevel_value,
 885                 struct agent *agt)
 886 {
 887         struct lttng_ht_node_str *node;
 888         struct lttng_ht_iter iter;
 889         struct lttng_ht *ht;
 890         struct agent_ht_key key;
 891
 892         assert(name);
 893         assert(agt);
 894         assert(agt->events);
 895
 896         ht = agt->events;
 897         key.name = name;
 898         key.loglevel_value = loglevel_value;
 899
 900         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 901                         ht_match_event, &key, &iter.iter);
 902         node = lttng_ht_iter_get_node_str(&iter);
 903         if (node == NULL) {
 904                 goto error;
 905         }
 906
 907         DBG3("Agent event found %s.", name);
 908         return caa_container_of(node, struct agent_event, node);
 909
 910 error:
 911         DBG3("Agent event NOT found %s.", name);
 912         return NULL;
 913 }
 914
 915 /*
 916  * Free given agent event. This event must not be globally visible at this
 917  * point (only expected to be used on failure just after event creation). After
 918  * this call, the pointer is not usable anymore.
 919  */
 920 void agent_destroy_event(struct agent_event *event)
 921 {
 922         assert(event);
 923
 924         free(event->filter);
 925         free(event->filter_expression);
 926         free(event->exclusion);
 927         free(event);
 928 }
 929
 930 /*
 931  * Destroy an agent completely.
 932  */
 933 void agent_destroy(struct agent *agt)
 934 {
 935         struct lttng_ht_node_str *node;
 936         struct lttng_ht_iter iter;
 937
 938         assert(agt);
 939
 940         DBG3("Agent destroy");
 941
 942         /*
 943          * Just ignore if no events hash table exists. This is possible if for
 944          * instance an agent object was allocated but not initialized.
 945          */
 946         if (!agt->events) {
 947                 return;
 948         }
 949
 950         rcu_read_lock();
 951         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, node, node) {
 952                 int ret;
 953                 struct agent_event *event;
 954
 955                 /*
 956                  * When destroying an event, we have to try to disable it on the agent
 957                  * side so the event stops generating data. The return value is not
 958                  * important since we have to continue anyway destroying the object.
 959                  */
 960                 event = caa_container_of(node, struct agent_event, node);
 961                 (void) agent_disable_event(event, agt->domain);
 962
 963                 ret = lttng_ht_del(agt->events, &iter);
 964                 assert(!ret);
 965                 call_rcu(&node->head, destroy_event_agent_rcu);
 966         }
 967         rcu_read_unlock();
 968
 969         ht_cleanup_push(agt->events);
 970         free(agt);
 971 }
 972
 973 /*
 974  * Allocate agent_apps_ht_by_sock.
 975  */
 976 int agent_app_ht_alloc(void)
 977 {
 978         int ret = 0;
 979
 980         agent_apps_ht_by_sock = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
 981         if (!agent_apps_ht_by_sock) {
 982                 ret = -1;
 983         }
 984
 985         return ret;
 986 }
 987
 988 /*
 989  * Destroy a agent application by socket.
 990  */
 991 void agent_destroy_app_by_sock(int sock)
 992 {
 993         struct agent_app *app;
 994
 995         assert(sock >= 0);
 996
 997         /*
 998          * Not finding an application is a very important error that should NEVER
 999          * happen. The hash table deletion is ONLY done through this call when the
1000          * main sessiond thread is torn down.
1001          */
1002         rcu_read_lock();
1003         app = agent_find_app_by_sock(sock);
1004         assert(app);
1005
1006         /* RCU read side lock is assumed to be held by this function. */
1007         agent_delete_app(app);
1008
1009         /* The application is freed in a RCU call but the socket is closed here. */
1010         agent_destroy_app(app);
1011         rcu_read_unlock();
1012 }
1013
1014 /*
1015  * Clean-up the agent app hash table and destroy it.
1016  */
1017 void agent_app_ht_clean(void)
1018 {
1019         struct lttng_ht_node_ulong *node;
1020         struct lttng_ht_iter iter;
1021
1022         if (!agent_apps_ht_by_sock) {
1023                 return;
1024         }
1025         rcu_read_lock();
1026         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, node, node) {
1027                 struct agent_app *app;
1028
1029                 app = caa_container_of(node, struct agent_app, node);
1030                 agent_destroy_app_by_sock(app->sock->fd);
1031         }
1032         rcu_read_unlock();
1033
1034         lttng_ht_destroy(agent_apps_ht_by_sock);
1035 }
1036
1037 /*
1038  * Update a agent application (given socket) using the given agent.
1039  *
1040  * Note that this function is most likely to be used with a tracing session
1041  * thus the caller should make sure to hold the appropriate lock(s).
1042  */
1043 void agent_update(struct agent *agt, int sock)
1044 {
1045         int ret;
1046         struct agent_app *app;
1047         struct agent_event *event;
1048         struct lttng_ht_iter iter;
1049
1050         assert(agt);
1051         assert(sock >= 0);
1052
1053         DBG("Agent updating app socket %d", sock);
1054
1055         rcu_read_lock();
1056         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, event, node.node) {
1057                 /* Skip event if disabled. */
1058                 if (!event->enabled) {
1059                         continue;
1060                 }
1061
1062                 app = agent_find_app_by_sock(sock);
1063                 /*
1064                  * We are in the registration path thus if the application is gone,
1065                  * there is a serious code flow error.
1066                  */
1067                 assert(app);
1068
1069                 ret = enable_event(app, event);
1070                 if (ret != LTTNG_OK) {
1071                         DBG2("Agent update unable to enable event %s on app pid: %d sock %d",
1072                                         event->name, app->pid, app->sock->fd);
1073                         /* Let's try the others here and don't assume the app is dead. */
1074                         continue;
1075                 }
1076         }
1077         rcu_read_unlock();
1078 }