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 #include "error.h"
  32
  33 #define AGENT_RET_CODE_INDEX(code) (code - AGENT_RET_CODE_SUCCESS)
  34
  35 /*
  36  * Human readable agent return code.
  37  */
  38 static const char *error_string_array[] = {
  39         [ AGENT_RET_CODE_INDEX(AGENT_RET_CODE_SUCCESS) ] = "Success",
  40         [ AGENT_RET_CODE_INDEX(AGENT_RET_CODE_INVALID) ] = "Invalid command",
  41         [ AGENT_RET_CODE_INDEX(AGENT_RET_CODE_UNKNOWN_NAME) ] = "Unknown logger name",
  42
  43         /* Last element */
  44         [ AGENT_RET_CODE_INDEX(AGENT_RET_CODE_NR) ] = "Unknown code",
  45 };
  46
  47 static
  48 void log_reply_code(uint32_t in_reply_ret_code)
  49 {
  50         int level = PRINT_DBG3;
  51         /*
  52          * reply_ret_code and in_reply_ret_code are kept separate to have a
  53          * sanitized value (used to retrieve the human readable string) and the
  54          * original value which is logged as-is.
  55          */
  56         uint32_t reply_ret_code = in_reply_ret_code;
  57
  58         if (reply_ret_code < AGENT_RET_CODE_SUCCESS ||
  59                         reply_ret_code >= AGENT_RET_CODE_NR) {
  60                 reply_ret_code = AGENT_RET_CODE_NR;
  61                 level = PRINT_ERR;
  62         }
  63
  64         LOG(level, "Agent replied with retcode: %s (%"PRIu32")",
  65                         error_string_array[AGENT_RET_CODE_INDEX(
  66                         reply_ret_code)],
  67                         in_reply_ret_code);
  68 }
  69
  70 /*
  71  * Match function for the events hash table lookup by name.
  72  */
  73 static int ht_match_event_by_name(struct cds_lfht_node *node,
  74                 const void *_key)
  75 {
  76         struct agent_event *event;
  77         const struct agent_ht_key *key;
  78
  79         assert(node);
  80         assert(_key);
  81
  82         event = caa_container_of(node, struct agent_event, node.node);
  83         key = _key;
  84
  85         /* Match 1 elements of the key: name. */
  86
  87         /* Event name */
  88         if (strncmp(event->name, key->name, sizeof(event->name)) != 0) {
  89                 goto no_match;
  90         }
  91         /* Match. */
  92         return 1;
  93
  94 no_match:
  95         return 0;
  96 }
  97
  98 /*
  99  * Match function for the events hash table lookup by name and loglevel.
 100  */
 101 static int ht_match_event(struct cds_lfht_node *node,
 102                 const void *_key)
 103 {
 104         struct agent_event *event;
 105         const struct agent_ht_key *key;
 106
 107         assert(node);
 108         assert(_key);
 109
 110         event = caa_container_of(node, struct agent_event, node.node);
 111         key = _key;
 112
 113         /* Match 2 elements of the key: name and loglevel. */
 114
 115         /* Event name */
 116         if (strncmp(event->name, key->name, sizeof(event->name)) != 0) {
 117                 goto no_match;
 118         }
 119
 120         if (event->loglevel_value != key->loglevel_value) {
 121                 if (event->loglevel_type == LTTNG_EVENT_LOGLEVEL_ALL &&
 122                                 key->loglevel_value == 0 &&
 123                                 event->loglevel_value == -1) {
 124                         goto match;
 125                 }
 126                 goto no_match;
 127         }
 128 match:
 129         return 1;
 130
 131 no_match:
 132         return 0;
 133 }
 134
 135 /*
 136  * Add unique agent event based on the event name and loglevel.
 137  */
 138 static void add_unique_agent_event(struct lttng_ht *ht,
 139                 struct agent_event *event)
 140 {
 141         struct cds_lfht_node *node_ptr;
 142         struct agent_ht_key key;
 143
 144         assert(ht);
 145         assert(ht->ht);
 146         assert(event);
 147
 148         key.name = event->name;
 149         key.loglevel_value = event->loglevel_value;
 150
 151         node_ptr = cds_lfht_add_unique(ht->ht,
 152                         ht->hash_fct(event->node.key, lttng_ht_seed),
 153                         ht_match_event, &key, &event->node.node);
 154         assert(node_ptr == &event->node.node);
 155 }
 156
 157 /*
 158  * URCU delayed agent event reclaim.
 159  */
 160 static void destroy_event_agent_rcu(struct rcu_head *head)
 161 {
 162         struct lttng_ht_node_str *node =
 163                 caa_container_of(head, struct lttng_ht_node_str, head);
 164         struct agent_event *event =
 165                 caa_container_of(node, struct agent_event, node);
 166
 167         agent_destroy_event(event);
 168 }
 169
 170 /*
 171  * URCU delayed agent app reclaim.
 172  */
 173 static void destroy_app_agent_rcu(struct rcu_head *head)
 174 {
 175         struct lttng_ht_node_ulong *node =
 176                 caa_container_of(head, struct lttng_ht_node_ulong, head);
 177         struct agent_app *app =
 178                 caa_container_of(node, struct agent_app, node);
 179
 180         free(app);
 181 }
 182
 183 /*
 184  * Communication with the agent. Send the message header to the given socket in
 185  * big endian.
 186  *
 187  * Return 0 on success or else a negative errno message of sendmsg() op.
 188  */
 189 static int send_header(struct lttcomm_sock *sock, uint64_t data_size,
 190                 uint32_t cmd, uint32_t cmd_version)
 191 {
 192         int ret;
 193         ssize_t size;
 194         struct lttcomm_agent_hdr msg;
 195
 196         assert(sock);
 197
 198         memset(&msg, 0, sizeof(msg));
 199         msg.data_size = htobe64(data_size);
 200         msg.cmd = htobe32(cmd);
 201         msg.cmd_version = htobe32(cmd_version);
 202
 203         size = sock->ops->sendmsg(sock, &msg, sizeof(msg), 0);
 204         if (size < sizeof(msg)) {
 205                 ret = -errno;
 206                 goto error;
 207         }
 208         ret = 0;
 209
 210 error:
 211         return ret;
 212 }
 213
 214 /*
 215  * Communication call with the agent. Send the payload to the given socket. The
 216  * header MUST be sent prior to this call.
 217  *
 218  * Return 0 on success or else a negative errno value of sendmsg() op.
 219  */
 220 static int send_payload(struct lttcomm_sock *sock, void *data,
 221                 size_t size)
 222 {
 223         int ret;
 224         ssize_t len;
 225
 226         assert(sock);
 227         assert(data);
 228
 229         len = sock->ops->sendmsg(sock, data, size, 0);
 230         if (len < size) {
 231                 ret = -errno;
 232                 goto error;
 233         }
 234         ret = 0;
 235
 236 error:
 237         return ret;
 238 }
 239
 240 /*
 241  * Communication call with the agent. Receive reply from the agent using the
 242  * given socket.
 243  *
 244  * Return 0 on success or else a negative errno value from recvmsg() op.
 245  */
 246 static int recv_reply(struct lttcomm_sock *sock, void *buf, size_t size)
 247 {
 248         int ret;
 249         ssize_t len;
 250
 251         assert(sock);
 252         assert(buf);
 253
 254         len = sock->ops->recvmsg(sock, buf, size, 0);
 255         if (len < size) {
 256                 ret = -errno;
 257                 goto error;
 258         }
 259         ret = 0;
 260
 261 error:
 262         return ret;
 263 }
 264
 265 /*
 266  * Internal event listing for a given app. Populate events.
 267  *
 268  * Return number of element in the list or else a negative LTTNG_ERR* code.
 269  * On success, the caller is responsible for freeing the memory
 270  * allocated for "events".
 271  */
 272 static ssize_t list_events(struct agent_app *app, struct lttng_event **events)
 273 {
 274         int ret, i, len = 0, offset = 0;
 275         uint32_t nb_event;
 276         size_t data_size;
 277         uint32_t reply_ret_code;
 278         struct lttng_event *tmp_events = NULL;
 279         struct lttcomm_agent_list_reply *reply = NULL;
 280         struct lttcomm_agent_list_reply_hdr reply_hdr;
 281
 282         assert(app);
 283         assert(app->sock);
 284         assert(events);
 285
 286         DBG2("Agent listing events for app pid: %d and socket %d", app->pid,
 287                         app->sock->fd);
 288
 289         ret = send_header(app->sock, 0, AGENT_CMD_LIST, 0);
 290         if (ret < 0) {
 291                 goto error_io;
 292         }
 293
 294         /* Get list header so we know how much we'll receive. */
 295         ret = recv_reply(app->sock, &reply_hdr, sizeof(reply_hdr));
 296         if (ret < 0) {
 297                 goto error_io;
 298         }
 299
 300         reply_ret_code = be32toh(reply_hdr.ret_code);
 301         log_reply_code(reply_ret_code);
 302         switch (reply_ret_code) {
 303         case AGENT_RET_CODE_SUCCESS:
 304                 data_size = be32toh(reply_hdr.data_size) + sizeof(*reply);
 305                 break;
 306         default:
 307                 ret = LTTNG_ERR_UNK;
 308                 goto error;
 309         }
 310
 311         reply = zmalloc(data_size);
 312         if (!reply) {
 313                 ret = LTTNG_ERR_NOMEM;
 314                 goto error;
 315         }
 316
 317         /* Get the list with the appropriate data size. */
 318         ret = recv_reply(app->sock, reply, data_size);
 319         if (ret < 0) {
 320                 goto error_io;
 321         }
 322
 323         nb_event = be32toh(reply->nb_event);
 324         tmp_events = zmalloc(sizeof(*tmp_events) * nb_event);
 325         if (!tmp_events) {
 326                 ret = LTTNG_ERR_NOMEM;
 327                 goto error;
 328         }
 329
 330         for (i = 0; i < nb_event; i++) {
 331                 offset += len;
 332                 strncpy(tmp_events[i].name, reply->payload + offset,
 333                                 sizeof(tmp_events[i].name));
 334                 tmp_events[i].pid = app->pid;
 335                 tmp_events[i].enabled = -1;
 336                 len = strlen(reply->payload + offset) + 1;
 337         }
 338
 339         *events = tmp_events;
 340
 341         free(reply);
 342         return nb_event;
 343
 344 error_io:
 345         ret = LTTNG_ERR_UST_LIST_FAIL;
 346 error:
 347         free(reply);
 348         free(tmp_events);
 349         return -ret;
 350
 351 }
 352
 353 /*
 354  * Internal enable agent event on a agent application. This function
 355  * communicates with the agent to enable a given event.
 356  *
 357  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 358  */
 359 static int enable_event(struct agent_app *app, struct agent_event *event)
 360 {
 361         int ret;
 362         uint64_t data_size;
 363         uint32_t reply_ret_code;
 364         struct lttcomm_agent_enable msg;
 365         struct lttcomm_agent_generic_reply reply;
 366
 367         assert(app);
 368         assert(app->sock);
 369         assert(event);
 370
 371         DBG2("Agent enabling event %s for app pid: %d and socket %d", event->name,
 372                         app->pid, app->sock->fd);
 373
 374         data_size = sizeof(msg);
 375
 376         ret = send_header(app->sock, data_size, AGENT_CMD_ENABLE, 0);
 377         if (ret < 0) {
 378                 goto error_io;
 379         }
 380
 381         memset(&msg, 0, sizeof(msg));
 382         msg.loglevel_value = event->loglevel_value;
 383         msg.loglevel_type = event->loglevel_type;
 384         strncpy(msg.name, event->name, sizeof(msg.name));
 385         ret = send_payload(app->sock, &msg, sizeof(msg));
 386         if (ret < 0) {
 387                 goto error_io;
 388         }
 389
 390         ret = recv_reply(app->sock, &reply, sizeof(reply));
 391         if (ret < 0) {
 392                 goto error_io;
 393         }
 394
 395         reply_ret_code = be32toh(reply.ret_code);
 396         log_reply_code(reply_ret_code);
 397         switch (reply_ret_code) {
 398         case AGENT_RET_CODE_SUCCESS:
 399                 break;
 400         case AGENT_RET_CODE_UNKNOWN_NAME:
 401                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 402                 goto error;
 403         default:
 404                 ret = LTTNG_ERR_UNK;
 405                 goto error;
 406         }
 407
 408         return LTTNG_OK;
 409
 410 error_io:
 411         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 412 error:
 413         return ret;
 414 }
 415
 416 /*
 417  * Internal disable agent event call on a agent application. This function
 418  * communicates with the agent to disable a given event.
 419  *
 420  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 421  */
 422 static int disable_event(struct agent_app *app, struct agent_event *event)
 423 {
 424         int ret;
 425         uint64_t data_size;
 426         uint32_t reply_ret_code;
 427         struct lttcomm_agent_disable msg;
 428         struct lttcomm_agent_generic_reply reply;
 429
 430         assert(app);
 431         assert(app->sock);
 432         assert(event);
 433
 434         DBG2("Agent disabling event %s for app pid: %d and socket %d", event->name,
 435                         app->pid, app->sock->fd);
 436
 437         data_size = sizeof(msg);
 438
 439         ret = send_header(app->sock, data_size, AGENT_CMD_DISABLE, 0);
 440         if (ret < 0) {
 441                 goto error_io;
 442         }
 443
 444         memset(&msg, 0, sizeof(msg));
 445         strncpy(msg.name, event->name, sizeof(msg.name));
 446         ret = send_payload(app->sock, &msg, sizeof(msg));
 447         if (ret < 0) {
 448                 goto error_io;
 449         }
 450
 451         ret = recv_reply(app->sock, &reply, sizeof(reply));
 452         if (ret < 0) {
 453                 goto error_io;
 454         }
 455
 456         reply_ret_code = be32toh(reply.ret_code);
 457         log_reply_code(reply_ret_code);
 458         switch (reply_ret_code) {
 459         case AGENT_RET_CODE_SUCCESS:
 460                 break;
 461         case AGENT_RET_CODE_UNKNOWN_NAME:
 462                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 463                 goto error;
 464         default:
 465                 ret = LTTNG_ERR_UNK;
 466                 goto error;
 467         }
 468
 469         return LTTNG_OK;
 470
 471 error_io:
 472         ret = LTTNG_ERR_UST_DISABLE_FAIL;
 473 error:
 474         return ret;
 475 }
 476
 477 /*
 478  * Send back the registration DONE command to a given agent application.
 479  *
 480  * Return 0 on success or else a negative value.
 481  */
 482 int agent_send_registration_done(struct agent_app *app)
 483 {
 484         assert(app);
 485         assert(app->sock);
 486
 487         DBG("Agent sending registration done to app socket %d", app->sock->fd);
 488
 489         return send_header(app->sock, 0, AGENT_CMD_REG_DONE, 0);
 490 }
 491
 492 /*
 493  * Enable agent event on every agent applications registered with the session
 494  * daemon.
 495  *
 496  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 497  */
 498 int agent_enable_event(struct agent_event *event,
 499                 enum lttng_domain_type domain)
 500 {
 501         int ret;
 502         struct agent_app *app;
 503         struct lttng_ht_iter iter;
 504
 505         assert(event);
 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 = enable_event(app, event);
 517                 if (ret != LTTNG_OK) {
 518                         goto error;
 519                 }
 520         }
 521
 522         event->enabled = 1;
 523         ret = LTTNG_OK;
 524
 525 error:
 526         rcu_read_unlock();
 527         return ret;
 528 }
 529
 530 /*
 531  * Disable agent event on every agent applications registered with the session
 532  * daemon.
 533  *
 534  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 535  */
 536 int agent_disable_event(struct agent_event *event,
 537                 enum lttng_domain_type domain)
 538 {
 539         int ret = LTTNG_OK;
 540         struct agent_app *app;
 541         struct lttng_ht_iter iter;
 542
 543         assert(event);
 544         if (!event->enabled) {
 545                 goto end;
 546         }
 547
 548         rcu_read_lock();
 549
 550         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 551                         node.node) {
 552                 if (app->domain != domain) {
 553                         continue;
 554                 }
 555
 556                 /* Enable event on agent application through TCP socket. */
 557                 ret = disable_event(app, event);
 558                 if (ret != LTTNG_OK) {
 559                         goto error;
 560                 }
 561         }
 562
 563         event->enabled = 0;
 564
 565 error:
 566         rcu_read_unlock();
 567 end:
 568         return ret;
 569 }
 570
 571 /*
 572  * Ask every agent for the list of possible event. Events is allocated with the
 573  * events of every agent application.
 574  *
 575  * Return the number of events or else a negative value.
 576  */
 577 int agent_list_events(struct lttng_event **events,
 578                 enum lttng_domain_type domain)
 579 {
 580         int ret;
 581         size_t nbmem, count = 0;
 582         struct agent_app *app;
 583         struct lttng_event *tmp_events = NULL;
 584         struct lttng_ht_iter iter;
 585
 586         assert(events);
 587
 588         DBG2("Agent listing events for domain %d", domain);
 589
 590         nbmem = UST_APP_EVENT_LIST_SIZE;
 591         tmp_events = zmalloc(nbmem * sizeof(*tmp_events));
 592         if (!tmp_events) {
 593                 PERROR("zmalloc agent list events");
 594                 ret = -ENOMEM;
 595                 goto error;
 596         }
 597
 598         rcu_read_lock();
 599         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 600                         node.node) {
 601                 ssize_t nb_ev;
 602                 struct lttng_event *agent_events;
 603
 604                 /* Skip domain not asked by the list. */
 605                 if (app->domain != domain) {
 606                         continue;
 607                 }
 608
 609                 nb_ev = list_events(app, &agent_events);
 610                 if (nb_ev < 0) {
 611                         ret = nb_ev;
 612                         goto error_unlock;
 613                 }
 614
 615                 if (count + nb_ev > nbmem) {
 616                         /* In case the realloc fails, we free the memory */
 617                         struct lttng_event *new_tmp_events;
 618                         size_t new_nbmem;
 619
 620                         new_nbmem = max_t(size_t, count + nb_ev, nbmem << 1);
 621                         DBG2("Reallocating agent event list from %zu to %zu entries",
 622                                         nbmem, new_nbmem);
 623                         new_tmp_events = realloc(tmp_events,
 624                                 new_nbmem * sizeof(*new_tmp_events));
 625                         if (!new_tmp_events) {
 626                                 PERROR("realloc agent events");
 627                                 ret = -ENOMEM;
 628                                 free(agent_events);
 629                                 goto error_unlock;
 630                         }
 631                         /* Zero the new memory */
 632                         memset(new_tmp_events + nbmem, 0,
 633                                 (new_nbmem - nbmem) * sizeof(*new_tmp_events));
 634                         nbmem = new_nbmem;
 635                         tmp_events = new_tmp_events;
 636                 }
 637                 memcpy(tmp_events + count, agent_events,
 638                         nb_ev * sizeof(*tmp_events));
 639                 free(agent_events);
 640                 count += nb_ev;
 641         }
 642         rcu_read_unlock();
 643
 644         ret = count;
 645         *events = tmp_events;
 646         return ret;
 647
 648 error_unlock:
 649         rcu_read_unlock();
 650 error:
 651         free(tmp_events);
 652         return ret;
 653 }
 654
 655 /*
 656  * Create a agent app object using the given PID.
 657  *
 658  * Return newly allocated object or else NULL on error.
 659  */
 660 struct agent_app *agent_create_app(pid_t pid, enum lttng_domain_type domain,
 661                 struct lttcomm_sock *sock)
 662 {
 663         struct agent_app *app;
 664
 665         assert(sock);
 666
 667         app = zmalloc(sizeof(*app));
 668         if (!app) {
 669                 PERROR("zmalloc agent create");
 670                 goto error;
 671         }
 672
 673         app->pid = pid;
 674         app->domain = domain;
 675         app->sock = sock;
 676         lttng_ht_node_init_ulong(&app->node, (unsigned long) app->sock->fd);
 677
 678 error:
 679         return app;
 680 }
 681
 682 /*
 683  * Lookup agent app by socket in the global hash table.
 684  *
 685  * RCU read side lock MUST be acquired.
 686  *
 687  * Return object if found else NULL.
 688  */
 689 struct agent_app *agent_find_app_by_sock(int sock)
 690 {
 691         struct lttng_ht_node_ulong *node;
 692         struct lttng_ht_iter iter;
 693         struct agent_app *app;
 694
 695         assert(sock >= 0);
 696
 697         lttng_ht_lookup(agent_apps_ht_by_sock, (void *)((unsigned long) sock), &iter);
 698         node = lttng_ht_iter_get_node_ulong(&iter);
 699         if (node == NULL) {
 700                 goto error;
 701         }
 702         app = caa_container_of(node, struct agent_app, node);
 703
 704         DBG3("Agent app pid %d found by sock %d.", app->pid, sock);
 705         return app;
 706
 707 error:
 708         DBG3("Agent app NOT found by sock %d.", sock);
 709         return NULL;
 710 }
 711
 712 /*
 713  * Add agent application object to the global hash table.
 714  */
 715 void agent_add_app(struct agent_app *app)
 716 {
 717         assert(app);
 718
 719         DBG3("Agent adding app sock: %d and pid: %d to ht", app->sock->fd, app->pid);
 720         lttng_ht_add_unique_ulong(agent_apps_ht_by_sock, &app->node);
 721 }
 722
 723 /*
 724  * Delete agent application from the global hash table.
 725  *
 726  * rcu_read_lock() must be held by the caller.
 727  */
 728 void agent_delete_app(struct agent_app *app)
 729 {
 730         int ret;
 731         struct lttng_ht_iter iter;
 732
 733         assert(app);
 734
 735         DBG3("Agent deleting app pid: %d and sock: %d", app->pid, app->sock->fd);
 736
 737         iter.iter.node = &app->node.node;
 738         ret = lttng_ht_del(agent_apps_ht_by_sock, &iter);
 739         assert(!ret);
 740 }
 741
 742 /*
 743  * Destroy an agent application object by detaching it from its corresponding
 744  * UST app if one is connected by closing the socket. Finally, perform a
 745  * delayed memory reclaim.
 746  */
 747 void agent_destroy_app(struct agent_app *app)
 748 {
 749         assert(app);
 750
 751         if (app->sock) {
 752                 app->sock->ops->close(app->sock);
 753                 lttcomm_destroy_sock(app->sock);
 754         }
 755
 756         call_rcu(&app->node.head, destroy_app_agent_rcu);
 757 }
 758
 759 /*
 760  * Initialize an already allocated agent object.
 761  *
 762  * Return 0 on success or else a negative errno value.
 763  */
 764 int agent_init(struct agent *agt)
 765 {
 766         int ret;
 767
 768         assert(agt);
 769
 770         agt->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 771         if (!agt->events) {
 772                 ret = -ENOMEM;
 773                 goto error;
 774         }
 775         lttng_ht_node_init_u64(&agt->node, agt->domain);
 776
 777         return 0;
 778
 779 error:
 780         return ret;
 781 }
 782
 783 /*
 784  * Add agent object to the given hash table.
 785  */
 786 void agent_add(struct agent *agt, struct lttng_ht *ht)
 787 {
 788         assert(agt);
 789         assert(ht);
 790
 791         DBG3("Agent adding from domain %d", agt->domain);
 792
 793         lttng_ht_add_unique_u64(ht, &agt->node);
 794 }
 795
 796 /*
 797  * Create an agent object for the given domain.
 798  *
 799  * Return the allocated agent or NULL on error.
 800  */
 801 struct agent *agent_create(enum lttng_domain_type domain)
 802 {
 803         int ret;
 804         struct agent *agt;
 805
 806         agt = zmalloc(sizeof(struct agent));
 807         if (!agt) {
 808                 goto error;
 809         }
 810         agt->domain = domain;
 811
 812         ret = agent_init(agt);
 813         if (ret < 0) {
 814                 free(agt);
 815                 agt = NULL;
 816                 goto error;
 817         }
 818
 819 error:
 820         return agt;
 821 }
 822
 823 /*
 824  * Create a newly allocated agent event data structure.
 825  * Ownership of filter_expression is taken.
 826  *
 827  * Return a new object else NULL on error.
 828  */
 829 struct agent_event *agent_create_event(const char *name,
 830                 int loglevel_value, enum lttng_loglevel_type loglevel_type,
 831                 struct lttng_filter_bytecode *filter, char *filter_expression)
 832 {
 833         struct agent_event *event = NULL;
 834
 835         DBG3("Agent create new event with name %s", name);
 836
 837         if (!name) {
 838                 ERR("Failed to create agent event; no name provided.");
 839                 goto error;
 840         }
 841
 842         event = zmalloc(sizeof(*event));
 843         if (!event) {
 844                 goto error;
 845         }
 846
 847         strncpy(event->name, name, sizeof(event->name));
 848         event->name[sizeof(event->name) - 1] = '\0';
 849         lttng_ht_node_init_str(&event->node, event->name);
 850
 851         event->loglevel_value = loglevel_value;
 852         event->loglevel_type = loglevel_type;
 853         event->filter = filter;
 854         event->filter_expression = filter_expression;
 855 error:
 856         return event;
 857 }
 858
 859 /*
 860  * Unique add of a agent event to an agent object.
 861  */
 862 void agent_add_event(struct agent_event *event, struct agent *agt)
 863 {
 864         assert(event);
 865         assert(agt);
 866         assert(agt->events);
 867
 868         DBG3("Agent adding event %s", event->name);
 869         add_unique_agent_event(agt->events, event);
 870         agt->being_used = 1;
 871 }
 872
 873 /*
 874  * Find a agent event in the given agent using name.
 875  *
 876  * RCU read side lock MUST be acquired.
 877  *
 878  * Return object if found else NULL.
 879  */
 880 struct agent_event *agent_find_event_by_name(const char *name,
 881                 struct agent *agt)
 882 {
 883         struct lttng_ht_node_str *node;
 884         struct lttng_ht_iter iter;
 885         struct lttng_ht *ht;
 886         struct agent_ht_key key;
 887
 888         assert(name);
 889         assert(agt);
 890         assert(agt->events);
 891
 892         ht = agt->events;
 893         key.name = name;
 894
 895         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 896                         ht_match_event_by_name, &key, &iter.iter);
 897         node = lttng_ht_iter_get_node_str(&iter);
 898         if (node == NULL) {
 899                 goto error;
 900         }
 901
 902         DBG3("Agent event found %s by name.", name);
 903         return caa_container_of(node, struct agent_event, node);
 904
 905 error:
 906         DBG3("Agent NOT found by name %s.", name);
 907         return NULL;
 908 }
 909
 910 /*
 911  * Find a agent event in the given agent using name and loglevel.
 912  *
 913  * RCU read side lock MUST be acquired.
 914  *
 915  * Return object if found else NULL.
 916  */
 917 struct agent_event *agent_find_event(const char *name, int loglevel_value,
 918                 struct agent *agt)
 919 {
 920         struct lttng_ht_node_str *node;
 921         struct lttng_ht_iter iter;
 922         struct lttng_ht *ht;
 923         struct agent_ht_key key;
 924
 925         assert(name);
 926         assert(agt);
 927         assert(agt->events);
 928
 929         ht = agt->events;
 930         key.name = name;
 931         key.loglevel_value = loglevel_value;
 932
 933         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 934                         ht_match_event, &key, &iter.iter);
 935         node = lttng_ht_iter_get_node_str(&iter);
 936         if (node == NULL) {
 937                 goto error;
 938         }
 939
 940         DBG3("Agent event found %s.", name);
 941         return caa_container_of(node, struct agent_event, node);
 942
 943 error:
 944         DBG3("Agent event NOT found %s.", name);
 945         return NULL;
 946 }
 947
 948 /*
 949  * Free given agent event. This event must not be globally visible at this
 950  * point (only expected to be used on failure just after event creation). After
 951  * this call, the pointer is not usable anymore.
 952  */
 953 void agent_destroy_event(struct agent_event *event)
 954 {
 955         assert(event);
 956
 957         free(event->filter);
 958         free(event->filter_expression);
 959         free(event->exclusion);
 960         free(event);
 961 }
 962
 963 /*
 964  * Destroy an agent completely.
 965  */
 966 void agent_destroy(struct agent *agt)
 967 {
 968         struct lttng_ht_node_str *node;
 969         struct lttng_ht_iter iter;
 970
 971         assert(agt);
 972
 973         DBG3("Agent destroy");
 974
 975         rcu_read_lock();
 976         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, node, node) {
 977                 int ret;
 978                 struct agent_event *event;
 979
 980                 /*
 981                  * When destroying an event, we have to try to disable it on the agent
 982                  * side so the event stops generating data. The return value is not
 983                  * important since we have to continue anyway destroying the object.
 984                  */
 985                 event = caa_container_of(node, struct agent_event, node);
 986                 (void) agent_disable_event(event, agt->domain);
 987
 988                 ret = lttng_ht_del(agt->events, &iter);
 989                 assert(!ret);
 990                 call_rcu(&node->head, destroy_event_agent_rcu);
 991         }
 992         rcu_read_unlock();
 993
 994         ht_cleanup_push(agt->events);
 995         free(agt);
 996 }
 997
 998 /*
 999  * Allocate agent_apps_ht_by_sock.
1000  */
1001 int agent_app_ht_alloc(void)
1002 {
1003         int ret = 0;
1004
1005         agent_apps_ht_by_sock = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
1006         if (!agent_apps_ht_by_sock) {
1007                 ret = -1;
1008         }
1009
1010         return ret;
1011 }
1012
1013 /*
1014  * Destroy a agent application by socket.
1015  */
1016 void agent_destroy_app_by_sock(int sock)
1017 {
1018         struct agent_app *app;
1019
1020         assert(sock >= 0);
1021
1022         /*
1023          * Not finding an application is a very important error that should NEVER
1024          * happen. The hash table deletion is ONLY done through this call when the
1025          * main sessiond thread is torn down.
1026          */
1027         rcu_read_lock();
1028         app = agent_find_app_by_sock(sock);
1029         assert(app);
1030
1031         /* RCU read side lock is assumed to be held by this function. */
1032         agent_delete_app(app);
1033
1034         /* The application is freed in a RCU call but the socket is closed here. */
1035         agent_destroy_app(app);
1036         rcu_read_unlock();
1037 }
1038
1039 /*
1040  * Clean-up the agent app hash table and destroy it.
1041  */
1042 void agent_app_ht_clean(void)
1043 {
1044         struct lttng_ht_node_ulong *node;
1045         struct lttng_ht_iter iter;
1046
1047         if (!agent_apps_ht_by_sock) {
1048                 return;
1049         }
1050         rcu_read_lock();
1051         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, node, node) {
1052                 struct agent_app *app;
1053
1054                 app = caa_container_of(node, struct agent_app, node);
1055                 agent_destroy_app_by_sock(app->sock->fd);
1056         }
1057         rcu_read_unlock();
1058
1059         lttng_ht_destroy(agent_apps_ht_by_sock);
1060 }
1061
1062 /*
1063  * Update a agent application (given socket) using the given agent.
1064  *
1065  * Note that this function is most likely to be used with a tracing session
1066  * thus the caller should make sure to hold the appropriate lock(s).
1067  */
1068 void agent_update(struct agent *agt, int sock)
1069 {
1070         int ret;
1071         struct agent_app *app;
1072         struct agent_event *event;
1073         struct lttng_ht_iter iter;
1074
1075         assert(agt);
1076         assert(sock >= 0);
1077
1078         DBG("Agent updating app socket %d", sock);
1079
1080         rcu_read_lock();
1081         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, event, node.node) {
1082                 /* Skip event if disabled. */
1083                 if (!event->enabled) {
1084                         continue;
1085                 }
1086
1087                 app = agent_find_app_by_sock(sock);
1088                 /*
1089                  * We are in the registration path thus if the application is gone,
1090                  * there is a serious code flow error.
1091                  */
1092                 assert(app);
1093
1094                 ret = enable_event(app, event);
1095                 if (ret != LTTNG_OK) {
1096                         DBG2("Agent update unable to enable event %s on app pid: %d sock %d",
1097                                         event->name, app->pid, app->sock->fd);
1098                         /* Let's try the others here and don't assume the app is dead. */
1099                         continue;
1100                 }
1101         }
1102         rcu_read_unlock();
1103 }