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         int ll_match;
  69
  70         assert(node);
  71         assert(_key);
  72
  73         event = caa_container_of(node, struct agent_event, node.node);
  74         key = _key;
  75
  76         /* Match 2 elements of the key: name and loglevel. */
  77
  78         /* Event name */
  79         if (strncmp(event->name, key->name, sizeof(event->name)) != 0) {
  80                 goto no_match;
  81         }
  82
  83         /* Event loglevel value and type. */
  84         ll_match = loglevels_match(event->loglevel_type,
  85                 event->loglevel_value, key->loglevel_type,
  86                 key->loglevel_value, LTTNG_EVENT_LOGLEVEL_ALL);
  87
  88         if (!ll_match) {
  89                 goto no_match;
  90         }
  91
  92         /* Filter expression */
  93         if (!!event->filter_expression ^ !!key->filter_expression) {
  94                 /* One has a filter expression, the other does not */
  95                 goto no_match;
  96         }
  97
  98         if (event->filter_expression) {
  99                 if (strncmp(event->filter_expression, key->filter_expression,
 100                                 strlen(event->filter_expression)) != 0) {
 101                         goto no_match;
 102                 }
 103         }
 104
 105         return 1;
 106
 107 no_match:
 108         return 0;
 109 }
 110
 111 /*
 112  * Add unique agent event based on the event name and loglevel.
 113  */
 114 static void add_unique_agent_event(struct lttng_ht *ht,
 115                 struct agent_event *event)
 116 {
 117         struct cds_lfht_node *node_ptr;
 118         struct agent_ht_key key;
 119
 120         assert(ht);
 121         assert(ht->ht);
 122         assert(event);
 123
 124         key.name = event->name;
 125         key.loglevel_value = event->loglevel_value;
 126         key.loglevel_type = event->loglevel_type;
 127         key.filter_expression = event->filter_expression;
 128
 129         node_ptr = cds_lfht_add_unique(ht->ht,
 130                         ht->hash_fct(event->node.key, lttng_ht_seed),
 131                         ht_match_event, &key, &event->node.node);
 132         assert(node_ptr == &event->node.node);
 133 }
 134
 135 /*
 136  * URCU delayed agent event reclaim.
 137  */
 138 static void destroy_event_agent_rcu(struct rcu_head *head)
 139 {
 140         struct lttng_ht_node_str *node =
 141                 caa_container_of(head, struct lttng_ht_node_str, head);
 142         struct agent_event *event =
 143                 caa_container_of(node, struct agent_event, node);
 144
 145         agent_destroy_event(event);
 146 }
 147
 148 /*
 149  * URCU delayed agent app reclaim.
 150  */
 151 static void destroy_app_agent_rcu(struct rcu_head *head)
 152 {
 153         struct lttng_ht_node_ulong *node =
 154                 caa_container_of(head, struct lttng_ht_node_ulong, head);
 155         struct agent_app *app =
 156                 caa_container_of(node, struct agent_app, node);
 157
 158         free(app);
 159 }
 160
 161 /*
 162  * Communication with the agent. Send the message header to the given socket in
 163  * big endian.
 164  *
 165  * Return 0 on success or else a negative errno message of sendmsg() op.
 166  */
 167 static int send_header(struct lttcomm_sock *sock, uint64_t data_size,
 168                 uint32_t cmd, uint32_t cmd_version)
 169 {
 170         int ret;
 171         ssize_t size;
 172         struct lttcomm_agent_hdr msg;
 173
 174         assert(sock);
 175
 176         memset(&msg, 0, sizeof(msg));
 177         msg.data_size = htobe64(data_size);
 178         msg.cmd = htobe32(cmd);
 179         msg.cmd_version = htobe32(cmd_version);
 180
 181         size = sock->ops->sendmsg(sock, &msg, sizeof(msg), 0);
 182         if (size < sizeof(msg)) {
 183                 ret = -errno;
 184                 goto error;
 185         }
 186         ret = 0;
 187
 188 error:
 189         return ret;
 190 }
 191
 192 /*
 193  * Communication call with the agent. Send the payload to the given socket. The
 194  * header MUST be sent prior to this call.
 195  *
 196  * Return 0 on success or else a negative errno value of sendmsg() op.
 197  */
 198 static int send_payload(struct lttcomm_sock *sock, void *data,
 199                 size_t size)
 200 {
 201         int ret;
 202         ssize_t len;
 203
 204         assert(sock);
 205         assert(data);
 206
 207         len = sock->ops->sendmsg(sock, data, size, 0);
 208         if (len < size) {
 209                 ret = -errno;
 210                 goto error;
 211         }
 212         ret = 0;
 213
 214 error:
 215         return ret;
 216 }
 217
 218 /*
 219  * Communication call with the agent. Receive reply from the agent using the
 220  * given socket.
 221  *
 222  * Return 0 on success or else a negative errno value from recvmsg() op.
 223  */
 224 static int recv_reply(struct lttcomm_sock *sock, void *buf, size_t size)
 225 {
 226         int ret;
 227         ssize_t len;
 228
 229         assert(sock);
 230         assert(buf);
 231
 232         len = sock->ops->recvmsg(sock, buf, size, 0);
 233         if (len < size) {
 234                 ret = -errno;
 235                 goto error;
 236         }
 237         ret = 0;
 238
 239 error:
 240         return ret;
 241 }
 242
 243 /*
 244  * Internal event listing for a given app. Populate events.
 245  *
 246  * Return number of element in the list or else a negative LTTNG_ERR* code.
 247  * On success, the caller is responsible for freeing the memory
 248  * allocated for "events".
 249  */
 250 static ssize_t list_events(struct agent_app *app, struct lttng_event **events)
 251 {
 252         int ret, i, len = 0, offset = 0;
 253         uint32_t nb_event;
 254         size_t data_size;
 255         struct lttng_event *tmp_events = NULL;
 256         struct lttcomm_agent_list_reply *reply = NULL;
 257         struct lttcomm_agent_list_reply_hdr reply_hdr;
 258
 259         assert(app);
 260         assert(app->sock);
 261         assert(events);
 262
 263         DBG2("Agent listing events for app pid: %d and socket %d", app->pid,
 264                         app->sock->fd);
 265
 266         ret = send_header(app->sock, 0, AGENT_CMD_LIST, 0);
 267         if (ret < 0) {
 268                 goto error_io;
 269         }
 270
 271         /* Get list header so we know how much we'll receive. */
 272         ret = recv_reply(app->sock, &reply_hdr, sizeof(reply_hdr));
 273         if (ret < 0) {
 274                 goto error_io;
 275         }
 276
 277         switch (be32toh(reply_hdr.ret_code)) {
 278         case AGENT_RET_CODE_SUCCESS:
 279                 data_size = be32toh(reply_hdr.data_size) + sizeof(*reply);
 280                 break;
 281         default:
 282                 ERR("Agent returned an unknown code: %" PRIu32,
 283                                 be32toh(reply_hdr.ret_code));
 284                 ret = LTTNG_ERR_FATAL;
 285                 goto error;
 286         }
 287
 288         reply = zmalloc(data_size);
 289         if (!reply) {
 290                 ret = LTTNG_ERR_NOMEM;
 291                 goto error;
 292         }
 293
 294         /* Get the list with the appropriate data size. */
 295         ret = recv_reply(app->sock, reply, data_size);
 296         if (ret < 0) {
 297                 goto error_io;
 298         }
 299
 300         nb_event = be32toh(reply->nb_event);
 301         tmp_events = zmalloc(sizeof(*tmp_events) * nb_event);
 302         if (!tmp_events) {
 303                 ret = LTTNG_ERR_NOMEM;
 304                 goto error;
 305         }
 306
 307         for (i = 0; i < nb_event; i++) {
 308                 offset += len;
 309                 if (lttng_strncpy(tmp_events[i].name, reply->payload + offset,
 310                                 sizeof(tmp_events[i].name))) {
 311                         ret = LTTNG_ERR_INVALID;
 312                         goto error;
 313                 }
 314                 tmp_events[i].pid = app->pid;
 315                 tmp_events[i].enabled = -1;
 316                 len = strlen(reply->payload + offset) + 1;
 317         }
 318
 319         *events = tmp_events;
 320
 321         free(reply);
 322         return nb_event;
 323
 324 error_io:
 325         ret = LTTNG_ERR_UST_LIST_FAIL;
 326 error:
 327         free(reply);
 328         free(tmp_events);
 329         return -ret;
 330
 331 }
 332
 333 /*
 334  * Internal enable agent event on a agent application. This function
 335  * communicates with the agent to enable a given event.
 336  *
 337  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 338  */
 339 static int enable_event(struct agent_app *app, struct agent_event *event)
 340 {
 341         int ret;
 342         uint64_t data_size;
 343         struct lttcomm_agent_enable msg;
 344         struct lttcomm_agent_generic_reply reply;
 345
 346         assert(app);
 347         assert(app->sock);
 348         assert(event);
 349
 350         DBG2("Agent enabling event %s for app pid: %d and socket %d", event->name,
 351                         app->pid, app->sock->fd);
 352
 353         data_size = sizeof(msg);
 354
 355         ret = send_header(app->sock, data_size, AGENT_CMD_ENABLE, 0);
 356         if (ret < 0) {
 357                 goto error_io;
 358         }
 359
 360         memset(&msg, 0, sizeof(msg));
 361         msg.loglevel_value = event->loglevel_value;
 362         msg.loglevel_type = event->loglevel_type;
 363         strncpy(msg.name, event->name, sizeof(msg.name));
 364         ret = send_payload(app->sock, &msg, sizeof(msg));
 365         if (ret < 0) {
 366                 goto error_io;
 367         }
 368
 369         ret = recv_reply(app->sock, &reply, sizeof(reply));
 370         if (ret < 0) {
 371                 goto error_io;
 372         }
 373
 374         switch (be32toh(reply.ret_code)) {
 375         case AGENT_RET_CODE_SUCCESS:
 376                 break;
 377         case AGENT_RET_CODE_UNKNOWN_NAME:
 378                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 379                 goto error;
 380         default:
 381                 ERR("Agent returned an unknown code: %" PRIu32,
 382                                 be32toh(reply.ret_code));
 383                 ret = LTTNG_ERR_FATAL;
 384                 goto error;
 385         }
 386
 387         return LTTNG_OK;
 388
 389 error_io:
 390         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 391 error:
 392         return ret;
 393 }
 394
 395 /*
 396  * Internal disable agent event call on a agent application. This function
 397  * communicates with the agent to disable a given event.
 398  *
 399  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 400  */
 401 static int disable_event(struct agent_app *app, struct agent_event *event)
 402 {
 403         int ret;
 404         uint64_t data_size;
 405         struct lttcomm_agent_disable msg;
 406         struct lttcomm_agent_generic_reply reply;
 407
 408         assert(app);
 409         assert(app->sock);
 410         assert(event);
 411
 412         DBG2("Agent disabling event %s for app pid: %d and socket %d", event->name,
 413                         app->pid, app->sock->fd);
 414
 415         data_size = sizeof(msg);
 416         memset(&msg, 0, sizeof(msg));
 417         if (lttng_strncpy(msg.name, event->name, sizeof(msg.name))) {
 418                 ret = LTTNG_ERR_INVALID;
 419                 goto error;
 420         }
 421
 422         ret = send_header(app->sock, data_size, AGENT_CMD_DISABLE, 0);
 423         if (ret < 0) {
 424                 goto error_io;
 425         }
 426
 427         ret = send_payload(app->sock, &msg, sizeof(msg));
 428         if (ret < 0) {
 429                 goto error_io;
 430         }
 431
 432         ret = recv_reply(app->sock, &reply, sizeof(reply));
 433         if (ret < 0) {
 434                 goto error_io;
 435         }
 436
 437         switch (be32toh(reply.ret_code)) {
 438         case AGENT_RET_CODE_SUCCESS:
 439                 break;
 440         case AGENT_RET_CODE_UNKNOWN_NAME:
 441                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 442                 goto error;
 443         default:
 444                 ERR("Agent returned an unknown code: %" PRIu32,
 445                                 be32toh(reply.ret_code));
 446                 ret = LTTNG_ERR_FATAL;
 447                 goto error;
 448         }
 449
 450         return LTTNG_OK;
 451
 452 error_io:
 453         ret = LTTNG_ERR_UST_DISABLE_FAIL;
 454 error:
 455         return ret;
 456 }
 457
 458 /*
 459  * Send back the registration DONE command to a given agent application.
 460  *
 461  * Return 0 on success or else a negative value.
 462  */
 463 int agent_send_registration_done(struct agent_app *app)
 464 {
 465         assert(app);
 466         assert(app->sock);
 467
 468         DBG("Agent sending registration done to app socket %d", app->sock->fd);
 469
 470         return send_header(app->sock, 0, AGENT_CMD_REG_DONE, 0);
 471 }
 472
 473 /*
 474  * Enable agent event on every agent applications registered with the session
 475  * daemon.
 476  *
 477  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 478  */
 479 int agent_enable_event(struct agent_event *event,
 480                 enum lttng_domain_type domain)
 481 {
 482         int ret;
 483         struct agent_app *app;
 484         struct lttng_ht_iter iter;
 485
 486         assert(event);
 487
 488         rcu_read_lock();
 489
 490         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 491                         node.node) {
 492                 if (app->domain != domain) {
 493                         continue;
 494                 }
 495
 496                 /* Enable event on agent application through TCP socket. */
 497                 ret = enable_event(app, event);
 498                 if (ret != LTTNG_OK) {
 499                         goto error;
 500                 }
 501         }
 502
 503         event->enabled = 1;
 504         ret = LTTNG_OK;
 505
 506 error:
 507         rcu_read_unlock();
 508         return ret;
 509 }
 510
 511 /*
 512  * Disable agent event on every agent applications registered with the session
 513  * daemon.
 514  *
 515  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 516  */
 517 int agent_disable_event(struct agent_event *event,
 518                 enum lttng_domain_type domain)
 519 {
 520         int ret = LTTNG_OK;
 521         struct agent_app *app;
 522         struct lttng_ht_iter iter;
 523
 524         assert(event);
 525         if (!event->enabled) {
 526                 goto end;
 527         }
 528
 529         rcu_read_lock();
 530
 531         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 532                         node.node) {
 533                 if (app->domain != domain) {
 534                         continue;
 535                 }
 536
 537                 /* Enable event on agent application through TCP socket. */
 538                 ret = disable_event(app, event);
 539                 if (ret != LTTNG_OK) {
 540                         goto error;
 541                 }
 542         }
 543
 544         event->enabled = 0;
 545
 546 error:
 547         rcu_read_unlock();
 548 end:
 549         return ret;
 550 }
 551
 552 /*
 553  * Ask every agent for the list of possible event. Events is allocated with the
 554  * events of every agent application.
 555  *
 556  * Return the number of events or else a negative value.
 557  */
 558 int agent_list_events(struct lttng_event **events,
 559                 enum lttng_domain_type domain)
 560 {
 561         int ret;
 562         size_t nbmem, count = 0;
 563         struct agent_app *app;
 564         struct lttng_event *tmp_events = NULL;
 565         struct lttng_ht_iter iter;
 566
 567         assert(events);
 568
 569         DBG2("Agent listing events for domain %d", domain);
 570
 571         nbmem = UST_APP_EVENT_LIST_SIZE;
 572         tmp_events = zmalloc(nbmem * sizeof(*tmp_events));
 573         if (!tmp_events) {
 574                 PERROR("zmalloc agent list events");
 575                 ret = -ENOMEM;
 576                 goto error;
 577         }
 578
 579         rcu_read_lock();
 580         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 581                         node.node) {
 582                 ssize_t nb_ev;
 583                 struct lttng_event *agent_events;
 584
 585                 /* Skip domain not asked by the list. */
 586                 if (app->domain != domain) {
 587                         continue;
 588                 }
 589
 590                 nb_ev = list_events(app, &agent_events);
 591                 if (nb_ev < 0) {
 592                         ret = nb_ev;
 593                         goto error_unlock;
 594                 }
 595
 596                 if (count + nb_ev > nbmem) {
 597                         /* In case the realloc fails, we free the memory */
 598                         struct lttng_event *new_tmp_events;
 599                         size_t new_nbmem;
 600
 601                         new_nbmem = max_t(size_t, count + nb_ev, nbmem << 1);
 602                         DBG2("Reallocating agent event list from %zu to %zu entries",
 603                                         nbmem, new_nbmem);
 604                         new_tmp_events = realloc(tmp_events,
 605                                 new_nbmem * sizeof(*new_tmp_events));
 606                         if (!new_tmp_events) {
 607                                 PERROR("realloc agent events");
 608                                 ret = -ENOMEM;
 609                                 free(agent_events);
 610                                 goto error_unlock;
 611                         }
 612                         /* Zero the new memory */
 613                         memset(new_tmp_events + nbmem, 0,
 614                                 (new_nbmem - nbmem) * sizeof(*new_tmp_events));
 615                         nbmem = new_nbmem;
 616                         tmp_events = new_tmp_events;
 617                 }
 618                 memcpy(tmp_events + count, agent_events,
 619                         nb_ev * sizeof(*tmp_events));
 620                 free(agent_events);
 621                 count += nb_ev;
 622         }
 623         rcu_read_unlock();
 624
 625         ret = count;
 626         *events = tmp_events;
 627         return ret;
 628
 629 error_unlock:
 630         rcu_read_unlock();
 631 error:
 632         free(tmp_events);
 633         return ret;
 634 }
 635
 636 /*
 637  * Create a agent app object using the given PID.
 638  *
 639  * Return newly allocated object or else NULL on error.
 640  */
 641 struct agent_app *agent_create_app(pid_t pid, enum lttng_domain_type domain,
 642                 struct lttcomm_sock *sock)
 643 {
 644         struct agent_app *app;
 645
 646         assert(sock);
 647
 648         app = zmalloc(sizeof(*app));
 649         if (!app) {
 650                 PERROR("zmalloc agent create");
 651                 goto error;
 652         }
 653
 654         app->pid = pid;
 655         app->domain = domain;
 656         app->sock = sock;
 657         lttng_ht_node_init_ulong(&app->node, (unsigned long) app->sock->fd);
 658
 659 error:
 660         return app;
 661 }
 662
 663 /*
 664  * Lookup agent app by socket in the global hash table.
 665  *
 666  * RCU read side lock MUST be acquired.
 667  *
 668  * Return object if found else NULL.
 669  */
 670 struct agent_app *agent_find_app_by_sock(int sock)
 671 {
 672         struct lttng_ht_node_ulong *node;
 673         struct lttng_ht_iter iter;
 674         struct agent_app *app;
 675
 676         assert(sock >= 0);
 677
 678         lttng_ht_lookup(agent_apps_ht_by_sock, (void *)((unsigned long) sock), &iter);
 679         node = lttng_ht_iter_get_node_ulong(&iter);
 680         if (node == NULL) {
 681                 goto error;
 682         }
 683         app = caa_container_of(node, struct agent_app, node);
 684
 685         DBG3("Agent app pid %d found by sock %d.", app->pid, sock);
 686         return app;
 687
 688 error:
 689         DBG3("Agent app NOT found by sock %d.", sock);
 690         return NULL;
 691 }
 692
 693 /*
 694  * Add agent application object to the global hash table.
 695  */
 696 void agent_add_app(struct agent_app *app)
 697 {
 698         assert(app);
 699
 700         DBG3("Agent adding app sock: %d and pid: %d to ht", app->sock->fd, app->pid);
 701
 702         rcu_read_lock();
 703         lttng_ht_add_unique_ulong(agent_apps_ht_by_sock, &app->node);
 704         rcu_read_unlock();
 705 }
 706
 707 /*
 708  * Delete agent application from the global hash table.
 709  *
 710  * rcu_read_lock() must be held by the caller.
 711  */
 712 void agent_delete_app(struct agent_app *app)
 713 {
 714         int ret;
 715         struct lttng_ht_iter iter;
 716
 717         assert(app);
 718
 719         DBG3("Agent deleting app pid: %d and sock: %d", app->pid, app->sock->fd);
 720
 721         iter.iter.node = &app->node.node;
 722         ret = lttng_ht_del(agent_apps_ht_by_sock, &iter);
 723         assert(!ret);
 724 }
 725
 726 /*
 727  * Destroy a agent application object by detaching it from its corresponding
 728  * UST app if one is connected by closing the socket. Finally, perform a
 729  * delayed memory reclaim.
 730  */
 731 void agent_destroy_app(struct agent_app *app)
 732 {
 733         assert(app);
 734
 735         if (app->sock) {
 736                 app->sock->ops->close(app->sock);
 737                 lttcomm_destroy_sock(app->sock);
 738         }
 739
 740         call_rcu(&app->node.head, destroy_app_agent_rcu);
 741 }
 742
 743 /*
 744  * Initialize an already allocated agent object.
 745  *
 746  * Return 0 on success or else a negative errno value.
 747  */
 748 int agent_init(struct agent *agt)
 749 {
 750         int ret;
 751
 752         assert(agt);
 753
 754         agt->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 755         if (!agt->events) {
 756                 ret = -ENOMEM;
 757                 goto error;
 758         }
 759         lttng_ht_node_init_u64(&agt->node, agt->domain);
 760
 761         return 0;
 762
 763 error:
 764         return ret;
 765 }
 766
 767 /*
 768  * Add agent object to the given hash table.
 769  */
 770 void agent_add(struct agent *agt, struct lttng_ht *ht)
 771 {
 772         assert(agt);
 773         assert(ht);
 774
 775         DBG3("Agent adding from domain %d", agt->domain);
 776
 777         rcu_read_lock();
 778         lttng_ht_add_unique_u64(ht, &agt->node);
 779         rcu_read_unlock();
 780 }
 781
 782 /*
 783  * Create an agent object for the given domain.
 784  *
 785  * Return the allocated agent or NULL on error.
 786  */
 787 struct agent *agent_create(enum lttng_domain_type domain)
 788 {
 789         int ret;
 790         struct agent *agt;
 791
 792         agt = zmalloc(sizeof(*agt));
 793         if (!agt) {
 794                 goto error;
 795         }
 796         agt->domain = domain;
 797
 798         ret = agent_init(agt);
 799         if (ret < 0) {
 800                 free(agt);
 801                 agt = NULL;
 802                 goto error;
 803         }
 804
 805 error:
 806         return agt;
 807 }
 808
 809 /*
 810  * Create a newly allocated agent event data structure.
 811  * Ownership of filter_expression is taken.
 812  *
 813  * Return a new object else NULL on error.
 814  */
 815 struct agent_event *agent_create_event(const char *name,
 816                 enum lttng_loglevel_type loglevel_type, int loglevel_value,
 817                 struct lttng_filter_bytecode *filter, char *filter_expression)
 818 {
 819         struct agent_event *event = NULL;
 820
 821         DBG3("Agent create new event with name %s, loglevel type %d, \
 822                         loglevel value %d and filter %s",
 823                         name, loglevel_type, loglevel_value,
 824                         filter_expression ? filter_expression : "NULL");
 825
 826         if (!name) {
 827                 ERR("Failed to create agent event; no name provided.");
 828                 goto error;
 829         }
 830
 831         event = zmalloc(sizeof(*event));
 832         if (!event) {
 833                 goto error;
 834         }
 835
 836         strncpy(event->name, name, sizeof(event->name));
 837         event->name[sizeof(event->name) - 1] = '\0';
 838         lttng_ht_node_init_str(&event->node, event->name);
 839
 840         event->loglevel_value = loglevel_value;
 841         event->loglevel_type = loglevel_type;
 842         event->filter = filter;
 843         event->filter_expression = filter_expression;
 844 error:
 845         return event;
 846 }
 847
 848 /*
 849  * Unique add of a agent event to an agent object.
 850  */
 851 void agent_add_event(struct agent_event *event, struct agent *agt)
 852 {
 853         assert(event);
 854         assert(agt);
 855         assert(agt->events);
 856
 857         DBG3("Agent adding event %s", event->name);
 858
 859         rcu_read_lock();
 860         add_unique_agent_event(agt->events, event);
 861         rcu_read_unlock();
 862         agt->being_used = 1;
 863 }
 864
 865 /*
 866  * Find multiple agent events sharing the given name.
 867  *
 868  * RCU read side lock MUST be acquired. It must be held for the
 869  * duration of the iteration.
 870  *
 871  * Sets the given iterator.
 872  */
 873 void agent_find_events_by_name(const char *name, struct agent *agt,
 874                 struct lttng_ht_iter* iter)
 875 {
 876         struct lttng_ht *ht;
 877         struct agent_ht_key key;
 878
 879         assert(name);
 880         assert(agt);
 881         assert(agt->events);
 882         assert(iter);
 883
 884         ht = agt->events;
 885         key.name = name;
 886
 887         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 888                         ht_match_event_by_name, &key, &iter->iter);
 889 }
 890
 891 /*
 892  * Get the next agent event duplicate by name. This should be called
 893  * after a call to agent_find_events_by_name() to iterate on events.
 894  *
 895  * The RCU read lock must be held during the iteration and for as long
 896  * as the object the iterator points to remains in use.
 897  */
 898 void agent_event_next_duplicate(const char *name,
 899                 struct agent *agt, struct lttng_ht_iter* iter)
 900 {
 901         struct agent_ht_key key;
 902
 903         key.name = name;
 904
 905         cds_lfht_next_duplicate(agt->events->ht, ht_match_event_by_name,
 906                 &key, &iter->iter);
 907 }
 908
 909 /*
 910  * Find a agent event in the given agent using name, loglevel and filter.
 911  *
 912  * RCU read side lock MUST be acquired.
 913  *
 914  * Return object if found else NULL.
 915  */
 916 struct agent_event *agent_find_event(const char *name,
 917                 enum lttng_loglevel_type loglevel_type, int loglevel_value,
 918                 char *filter_expression, 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         key.loglevel_type = loglevel_type;
 933         key.filter_expression = filter_expression;
 934
 935         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 936                         ht_match_event, &key, &iter.iter);
 937         node = lttng_ht_iter_get_node_str(&iter);
 938         if (node == NULL) {
 939                 goto error;
 940         }
 941
 942         DBG3("Agent event found %s.", name);
 943         return caa_container_of(node, struct agent_event, node);
 944
 945 error:
 946         DBG3("Agent event NOT found %s.", name);
 947         return NULL;
 948 }
 949
 950 /*
 951  * Free given agent event. This event must not be globally visible at this
 952  * point (only expected to be used on failure just after event creation). After
 953  * this call, the pointer is not usable anymore.
 954  */
 955 void agent_destroy_event(struct agent_event *event)
 956 {
 957         assert(event);
 958
 959         free(event->filter);
 960         free(event->filter_expression);
 961         free(event->exclusion);
 962         free(event);
 963 }
 964
 965 /*
 966  * Destroy an agent completely.
 967  */
 968 void agent_destroy(struct agent *agt)
 969 {
 970         struct lttng_ht_node_str *node;
 971         struct lttng_ht_iter iter;
 972
 973         assert(agt);
 974
 975         DBG3("Agent destroy");
 976
 977         /*
 978          * Just ignore if no events hash table exists. This is possible if for
 979          * instance an agent object was allocated but not initialized.
 980          */
 981         if (!agt->events) {
 982                 return;
 983         }
 984
 985         rcu_read_lock();
 986         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, node, node) {
 987                 int ret;
 988                 struct agent_event *event;
 989
 990                 /*
 991                  * When destroying an event, we have to try to disable it on the agent
 992                  * side so the event stops generating data. The return value is not
 993                  * important since we have to continue anyway destroying the object.
 994                  */
 995                 event = caa_container_of(node, struct agent_event, node);
 996                 (void) agent_disable_event(event, agt->domain);
 997
 998                 ret = lttng_ht_del(agt->events, &iter);
 999                 assert(!ret);
1000                 call_rcu(&node->head, destroy_event_agent_rcu);
1001         }
1002         rcu_read_unlock();
1003
1004         ht_cleanup_push(agt->events);
1005         free(agt);
1006 }
1007
1008 /*
1009  * Allocate agent_apps_ht_by_sock.
1010  */
1011 int agent_app_ht_alloc(void)
1012 {
1013         int ret = 0;
1014
1015         agent_apps_ht_by_sock = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
1016         if (!agent_apps_ht_by_sock) {
1017                 ret = -1;
1018         }
1019
1020         return ret;
1021 }
1022
1023 /*
1024  * Destroy a agent application by socket.
1025  */
1026 void agent_destroy_app_by_sock(int sock)
1027 {
1028         struct agent_app *app;
1029
1030         assert(sock >= 0);
1031
1032         /*
1033          * Not finding an application is a very important error that should NEVER
1034          * happen. The hash table deletion is ONLY done through this call when the
1035          * main sessiond thread is torn down.
1036          */
1037         rcu_read_lock();
1038         app = agent_find_app_by_sock(sock);
1039         assert(app);
1040
1041         /* RCU read side lock is assumed to be held by this function. */
1042         agent_delete_app(app);
1043
1044         /* The application is freed in a RCU call but the socket is closed here. */
1045         agent_destroy_app(app);
1046         rcu_read_unlock();
1047 }
1048
1049 /*
1050  * Clean-up the agent app hash table and destroy it.
1051  */
1052 void agent_app_ht_clean(void)
1053 {
1054         struct lttng_ht_node_ulong *node;
1055         struct lttng_ht_iter iter;
1056
1057         if (!agent_apps_ht_by_sock) {
1058                 return;
1059         }
1060         rcu_read_lock();
1061         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, node, node) {
1062                 struct agent_app *app;
1063
1064                 app = caa_container_of(node, struct agent_app, node);
1065                 agent_destroy_app_by_sock(app->sock->fd);
1066         }
1067         rcu_read_unlock();
1068
1069         lttng_ht_destroy(agent_apps_ht_by_sock);
1070 }
1071
1072 /*
1073  * Update a agent application (given socket) using the given agent.
1074  *
1075  * Note that this function is most likely to be used with a tracing session
1076  * thus the caller should make sure to hold the appropriate lock(s).
1077  */
1078 void agent_update(struct agent *agt, int sock)
1079 {
1080         int ret;
1081         struct agent_app *app;
1082         struct agent_event *event;
1083         struct lttng_ht_iter iter;
1084
1085         assert(agt);
1086         assert(sock >= 0);
1087
1088         DBG("Agent updating app socket %d", sock);
1089
1090         rcu_read_lock();
1091         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, event, node.node) {
1092                 /* Skip event if disabled. */
1093                 if (!event->enabled) {
1094                         continue;
1095                 }
1096
1097                 app = agent_find_app_by_sock(sock);
1098                 /*
1099                  * We are in the registration path thus if the application is gone,
1100                  * there is a serious code flow error.
1101                  */
1102                 assert(app);
1103
1104                 ret = enable_event(app, event);
1105                 if (ret != LTTNG_OK) {
1106                         DBG2("Agent update unable to enable event %s on app pid: %d sock %d",
1107                                         event->name, app->pid, app->sock->fd);
1108                         /* Let's try the others here and don't assume the app is dead. */
1109                         continue;
1110                 }
1111         }
1112         rcu_read_unlock();
1113 }