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