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         /* Event loglevel value and type. */
 121         if (event->loglevel_type == key->loglevel_type) {
 122                 /* Same loglevel type. */
 123                 if (key->loglevel_type != LTTNG_EVENT_LOGLEVEL_ALL) {
 124                         /*
 125                          * Loglevel value must also match since the loglevel
 126                          * type is not all.
 127                          */
 128                         if (event->loglevel_value != key->loglevel_value) {
 129                                 goto no_match;
 130                         }
 131                 }
 132         } else {
 133                 /* Loglevel type is different: no match. */
 134                 goto no_match;
 135         }
 136
 137         return 1;
 138
 139 no_match:
 140         return 0;
 141 }
 142
 143 /*
 144  * Add unique agent event based on the event name and loglevel.
 145  */
 146 static void add_unique_agent_event(struct lttng_ht *ht,
 147                 struct agent_event *event)
 148 {
 149         struct cds_lfht_node *node_ptr;
 150         struct agent_ht_key key;
 151
 152         assert(ht);
 153         assert(ht->ht);
 154         assert(event);
 155
 156         key.name = event->name;
 157         key.loglevel_value = event->loglevel_value;
 158         key.loglevel_type = event->loglevel_type;
 159
 160         node_ptr = cds_lfht_add_unique(ht->ht,
 161                         ht->hash_fct(event->node.key, lttng_ht_seed),
 162                         ht_match_event, &key, &event->node.node);
 163         assert(node_ptr == &event->node.node);
 164 }
 165
 166 /*
 167  * URCU delayed agent event reclaim.
 168  */
 169 static void destroy_event_agent_rcu(struct rcu_head *head)
 170 {
 171         struct lttng_ht_node_str *node =
 172                 caa_container_of(head, struct lttng_ht_node_str, head);
 173         struct agent_event *event =
 174                 caa_container_of(node, struct agent_event, node);
 175
 176         agent_destroy_event(event);
 177 }
 178
 179 /*
 180  * URCU delayed agent app reclaim.
 181  */
 182 static void destroy_app_agent_rcu(struct rcu_head *head)
 183 {
 184         struct lttng_ht_node_ulong *node =
 185                 caa_container_of(head, struct lttng_ht_node_ulong, head);
 186         struct agent_app *app =
 187                 caa_container_of(node, struct agent_app, node);
 188
 189         free(app);
 190 }
 191
 192 /*
 193  * Communication with the agent. Send the message header to the given socket in
 194  * big endian.
 195  *
 196  * Return 0 on success or else a negative errno message of sendmsg() op.
 197  */
 198 static int send_header(struct lttcomm_sock *sock, uint64_t data_size,
 199                 uint32_t cmd, uint32_t cmd_version)
 200 {
 201         int ret;
 202         ssize_t size;
 203         struct lttcomm_agent_hdr msg;
 204
 205         assert(sock);
 206
 207         memset(&msg, 0, sizeof(msg));
 208         msg.data_size = htobe64(data_size);
 209         msg.cmd = htobe32(cmd);
 210         msg.cmd_version = htobe32(cmd_version);
 211
 212         size = sock->ops->sendmsg(sock, &msg, sizeof(msg), 0);
 213         if (size < sizeof(msg)) {
 214                 ret = -errno;
 215                 goto error;
 216         }
 217         ret = 0;
 218
 219 error:
 220         return ret;
 221 }
 222
 223 /*
 224  * Communication call with the agent. Send the payload to the given socket. The
 225  * header MUST be sent prior to this call.
 226  *
 227  * Return 0 on success or else a negative errno value of sendmsg() op.
 228  */
 229 static int send_payload(struct lttcomm_sock *sock, void *data,
 230                 size_t size)
 231 {
 232         int ret;
 233         ssize_t len;
 234
 235         assert(sock);
 236         assert(data);
 237
 238         len = sock->ops->sendmsg(sock, data, size, 0);
 239         if (len < size) {
 240                 ret = -errno;
 241                 goto error;
 242         }
 243         ret = 0;
 244
 245 error:
 246         return ret;
 247 }
 248
 249 /*
 250  * Communication call with the agent. Receive reply from the agent using the
 251  * given socket.
 252  *
 253  * Return 0 on success or else a negative errno value from recvmsg() op.
 254  */
 255 static int recv_reply(struct lttcomm_sock *sock, void *buf, size_t size)
 256 {
 257         int ret;
 258         ssize_t len;
 259
 260         assert(sock);
 261         assert(buf);
 262
 263         len = sock->ops->recvmsg(sock, buf, size, 0);
 264         if (len < size) {
 265                 ret = -errno;
 266                 goto error;
 267         }
 268         ret = 0;
 269
 270 error:
 271         return ret;
 272 }
 273
 274 /*
 275  * Internal event listing for a given app. Populate events.
 276  *
 277  * Return number of element in the list or else a negative LTTNG_ERR* code.
 278  * On success, the caller is responsible for freeing the memory
 279  * allocated for "events".
 280  */
 281 static ssize_t list_events(struct agent_app *app, struct lttng_event **events)
 282 {
 283         int ret, i, len = 0, offset = 0;
 284         uint32_t nb_event;
 285         size_t data_size;
 286         uint32_t reply_ret_code;
 287         struct lttng_event *tmp_events = NULL;
 288         struct lttcomm_agent_list_reply *reply = NULL;
 289         struct lttcomm_agent_list_reply_hdr reply_hdr;
 290
 291         assert(app);
 292         assert(app->sock);
 293         assert(events);
 294
 295         DBG2("Agent listing events for app pid: %d and socket %d", app->pid,
 296                         app->sock->fd);
 297
 298         ret = send_header(app->sock, 0, AGENT_CMD_LIST, 0);
 299         if (ret < 0) {
 300                 goto error_io;
 301         }
 302
 303         /* Get list header so we know how much we'll receive. */
 304         ret = recv_reply(app->sock, &reply_hdr, sizeof(reply_hdr));
 305         if (ret < 0) {
 306                 goto error_io;
 307         }
 308
 309         reply_ret_code = be32toh(reply_hdr.ret_code);
 310         log_reply_code(reply_ret_code);
 311         switch (reply_ret_code) {
 312         case AGENT_RET_CODE_SUCCESS:
 313                 data_size = be32toh(reply_hdr.data_size) + sizeof(*reply);
 314                 break;
 315         default:
 316                 ret = LTTNG_ERR_UNK;
 317                 goto error;
 318         }
 319
 320         reply = zmalloc(data_size);
 321         if (!reply) {
 322                 ret = LTTNG_ERR_NOMEM;
 323                 goto error;
 324         }
 325
 326         /* Get the list with the appropriate data size. */
 327         ret = recv_reply(app->sock, reply, data_size);
 328         if (ret < 0) {
 329                 goto error_io;
 330         }
 331
 332         nb_event = be32toh(reply->nb_event);
 333         tmp_events = zmalloc(sizeof(*tmp_events) * nb_event);
 334         if (!tmp_events) {
 335                 ret = LTTNG_ERR_NOMEM;
 336                 goto error;
 337         }
 338
 339         for (i = 0; i < nb_event; i++) {
 340                 offset += len;
 341                 strncpy(tmp_events[i].name, reply->payload + offset,
 342                                 sizeof(tmp_events[i].name));
 343                 tmp_events[i].pid = app->pid;
 344                 tmp_events[i].enabled = -1;
 345                 len = strlen(reply->payload + offset) + 1;
 346         }
 347
 348         *events = tmp_events;
 349
 350         free(reply);
 351         return nb_event;
 352
 353 error_io:
 354         ret = LTTNG_ERR_UST_LIST_FAIL;
 355 error:
 356         free(reply);
 357         free(tmp_events);
 358         return -ret;
 359
 360 }
 361
 362 /*
 363  * Internal enable agent event on a agent application. This function
 364  * communicates with the agent to enable a given event.
 365  *
 366  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 367  */
 368 static int enable_event(struct agent_app *app, struct agent_event *event)
 369 {
 370         int ret;
 371         uint64_t data_size;
 372         uint32_t reply_ret_code;
 373         struct lttcomm_agent_enable msg;
 374         struct lttcomm_agent_generic_reply reply;
 375
 376         assert(app);
 377         assert(app->sock);
 378         assert(event);
 379
 380         DBG2("Agent enabling event %s for app pid: %d and socket %d", event->name,
 381                         app->pid, app->sock->fd);
 382
 383         data_size = sizeof(msg);
 384
 385         ret = send_header(app->sock, data_size, AGENT_CMD_ENABLE, 0);
 386         if (ret < 0) {
 387                 goto error_io;
 388         }
 389
 390         memset(&msg, 0, sizeof(msg));
 391         msg.loglevel_value = event->loglevel_value;
 392         msg.loglevel_type = event->loglevel_type;
 393         strncpy(msg.name, event->name, sizeof(msg.name));
 394         ret = send_payload(app->sock, &msg, sizeof(msg));
 395         if (ret < 0) {
 396                 goto error_io;
 397         }
 398
 399         ret = recv_reply(app->sock, &reply, sizeof(reply));
 400         if (ret < 0) {
 401                 goto error_io;
 402         }
 403
 404         reply_ret_code = be32toh(reply.ret_code);
 405         log_reply_code(reply_ret_code);
 406         switch (reply_ret_code) {
 407         case AGENT_RET_CODE_SUCCESS:
 408                 break;
 409         case AGENT_RET_CODE_UNKNOWN_NAME:
 410                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 411                 goto error;
 412         default:
 413                 ret = LTTNG_ERR_UNK;
 414                 goto error;
 415         }
 416
 417         return LTTNG_OK;
 418
 419 error_io:
 420         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 421 error:
 422         return ret;
 423 }
 424
 425 /*
 426  * Internal disable agent event call on a agent application. This function
 427  * communicates with the agent to disable a given event.
 428  *
 429  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 430  */
 431 static int disable_event(struct agent_app *app, struct agent_event *event)
 432 {
 433         int ret;
 434         uint64_t data_size;
 435         uint32_t reply_ret_code;
 436         struct lttcomm_agent_disable msg;
 437         struct lttcomm_agent_generic_reply reply;
 438
 439         assert(app);
 440         assert(app->sock);
 441         assert(event);
 442
 443         DBG2("Agent disabling event %s for app pid: %d and socket %d", event->name,
 444                         app->pid, app->sock->fd);
 445
 446         data_size = sizeof(msg);
 447
 448         ret = send_header(app->sock, data_size, AGENT_CMD_DISABLE, 0);
 449         if (ret < 0) {
 450                 goto error_io;
 451         }
 452
 453         memset(&msg, 0, sizeof(msg));
 454         strncpy(msg.name, event->name, sizeof(msg.name));
 455         ret = send_payload(app->sock, &msg, sizeof(msg));
 456         if (ret < 0) {
 457                 goto error_io;
 458         }
 459
 460         ret = recv_reply(app->sock, &reply, sizeof(reply));
 461         if (ret < 0) {
 462                 goto error_io;
 463         }
 464
 465         reply_ret_code = be32toh(reply.ret_code);
 466         log_reply_code(reply_ret_code);
 467         switch (reply_ret_code) {
 468         case AGENT_RET_CODE_SUCCESS:
 469                 break;
 470         case AGENT_RET_CODE_UNKNOWN_NAME:
 471                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 472                 goto error;
 473         default:
 474                 ret = LTTNG_ERR_UNK;
 475                 goto error;
 476         }
 477
 478         return LTTNG_OK;
 479
 480 error_io:
 481         ret = LTTNG_ERR_UST_DISABLE_FAIL;
 482 error:
 483         return ret;
 484 }
 485
 486 /*
 487  * Send back the registration DONE command to a given agent application.
 488  *
 489  * Return 0 on success or else a negative value.
 490  */
 491 int agent_send_registration_done(struct agent_app *app)
 492 {
 493         assert(app);
 494         assert(app->sock);
 495
 496         DBG("Agent sending registration done to app socket %d", app->sock->fd);
 497
 498         return send_header(app->sock, 0, AGENT_CMD_REG_DONE, 0);
 499 }
 500
 501 /*
 502  * Enable agent event on every agent applications registered with the session
 503  * daemon.
 504  *
 505  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 506  */
 507 int agent_enable_event(struct agent_event *event,
 508                 enum lttng_domain_type domain)
 509 {
 510         int ret;
 511         struct agent_app *app;
 512         struct lttng_ht_iter iter;
 513
 514         assert(event);
 515
 516         rcu_read_lock();
 517
 518         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 519                         node.node) {
 520                 if (app->domain != domain) {
 521                         continue;
 522                 }
 523
 524                 /* Enable event on agent application through TCP socket. */
 525                 ret = enable_event(app, event);
 526                 if (ret != LTTNG_OK) {
 527                         goto error;
 528                 }
 529         }
 530
 531         event->enabled = 1;
 532         ret = LTTNG_OK;
 533
 534 error:
 535         rcu_read_unlock();
 536         return ret;
 537 }
 538
 539 /*
 540  * Disable agent event on every agent applications registered with the session
 541  * daemon.
 542  *
 543  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 544  */
 545 int agent_disable_event(struct agent_event *event,
 546                 enum lttng_domain_type domain)
 547 {
 548         int ret = LTTNG_OK;
 549         struct agent_app *app;
 550         struct lttng_ht_iter iter;
 551
 552         assert(event);
 553         if (!event->enabled) {
 554                 goto end;
 555         }
 556
 557         rcu_read_lock();
 558
 559         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 560                         node.node) {
 561                 if (app->domain != domain) {
 562                         continue;
 563                 }
 564
 565                 /* Enable event on agent application through TCP socket. */
 566                 ret = disable_event(app, event);
 567                 if (ret != LTTNG_OK) {
 568                         goto error;
 569                 }
 570         }
 571
 572         event->enabled = 0;
 573
 574 error:
 575         rcu_read_unlock();
 576 end:
 577         return ret;
 578 }
 579
 580 /*
 581  * Ask every agent for the list of possible event. Events is allocated with the
 582  * events of every agent application.
 583  *
 584  * Return the number of events or else a negative value.
 585  */
 586 int agent_list_events(struct lttng_event **events,
 587                 enum lttng_domain_type domain)
 588 {
 589         int ret;
 590         size_t nbmem, count = 0;
 591         struct agent_app *app;
 592         struct lttng_event *tmp_events = NULL;
 593         struct lttng_ht_iter iter;
 594
 595         assert(events);
 596
 597         DBG2("Agent listing events for domain %d", domain);
 598
 599         nbmem = UST_APP_EVENT_LIST_SIZE;
 600         tmp_events = zmalloc(nbmem * sizeof(*tmp_events));
 601         if (!tmp_events) {
 602                 PERROR("zmalloc agent list events");
 603                 ret = -ENOMEM;
 604                 goto error;
 605         }
 606
 607         rcu_read_lock();
 608         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 609                         node.node) {
 610                 ssize_t nb_ev;
 611                 struct lttng_event *agent_events;
 612
 613                 /* Skip domain not asked by the list. */
 614                 if (app->domain != domain) {
 615                         continue;
 616                 }
 617
 618                 nb_ev = list_events(app, &agent_events);
 619                 if (nb_ev < 0) {
 620                         ret = nb_ev;
 621                         goto error_unlock;
 622                 }
 623
 624                 if (count + nb_ev > nbmem) {
 625                         /* In case the realloc fails, we free the memory */
 626                         struct lttng_event *new_tmp_events;
 627                         size_t new_nbmem;
 628
 629                         new_nbmem = max_t(size_t, count + nb_ev, nbmem << 1);
 630                         DBG2("Reallocating agent event list from %zu to %zu entries",
 631                                         nbmem, new_nbmem);
 632                         new_tmp_events = realloc(tmp_events,
 633                                 new_nbmem * sizeof(*new_tmp_events));
 634                         if (!new_tmp_events) {
 635                                 PERROR("realloc agent events");
 636                                 ret = -ENOMEM;
 637                                 free(agent_events);
 638                                 goto error_unlock;
 639                         }
 640                         /* Zero the new memory */
 641                         memset(new_tmp_events + nbmem, 0,
 642                                 (new_nbmem - nbmem) * sizeof(*new_tmp_events));
 643                         nbmem = new_nbmem;
 644                         tmp_events = new_tmp_events;
 645                 }
 646                 memcpy(tmp_events + count, agent_events,
 647                         nb_ev * sizeof(*tmp_events));
 648                 free(agent_events);
 649                 count += nb_ev;
 650         }
 651         rcu_read_unlock();
 652
 653         ret = count;
 654         *events = tmp_events;
 655         return ret;
 656
 657 error_unlock:
 658         rcu_read_unlock();
 659 error:
 660         free(tmp_events);
 661         return ret;
 662 }
 663
 664 /*
 665  * Create a agent app object using the given PID.
 666  *
 667  * Return newly allocated object or else NULL on error.
 668  */
 669 struct agent_app *agent_create_app(pid_t pid, enum lttng_domain_type domain,
 670                 struct lttcomm_sock *sock)
 671 {
 672         struct agent_app *app;
 673
 674         assert(sock);
 675
 676         app = zmalloc(sizeof(*app));
 677         if (!app) {
 678                 PERROR("zmalloc agent create");
 679                 goto error;
 680         }
 681
 682         app->pid = pid;
 683         app->domain = domain;
 684         app->sock = sock;
 685         lttng_ht_node_init_ulong(&app->node, (unsigned long) app->sock->fd);
 686
 687 error:
 688         return app;
 689 }
 690
 691 /*
 692  * Lookup agent app by socket in the global hash table.
 693  *
 694  * RCU read side lock MUST be acquired.
 695  *
 696  * Return object if found else NULL.
 697  */
 698 struct agent_app *agent_find_app_by_sock(int sock)
 699 {
 700         struct lttng_ht_node_ulong *node;
 701         struct lttng_ht_iter iter;
 702         struct agent_app *app;
 703
 704         assert(sock >= 0);
 705
 706         lttng_ht_lookup(agent_apps_ht_by_sock, (void *)((unsigned long) sock), &iter);
 707         node = lttng_ht_iter_get_node_ulong(&iter);
 708         if (node == NULL) {
 709                 goto error;
 710         }
 711         app = caa_container_of(node, struct agent_app, node);
 712
 713         DBG3("Agent app pid %d found by sock %d.", app->pid, sock);
 714         return app;
 715
 716 error:
 717         DBG3("Agent app NOT found by sock %d.", sock);
 718         return NULL;
 719 }
 720
 721 /*
 722  * Add agent application object to the global hash table.
 723  */
 724 void agent_add_app(struct agent_app *app)
 725 {
 726         assert(app);
 727
 728         DBG3("Agent adding app sock: %d and pid: %d to ht", app->sock->fd, app->pid);
 729         lttng_ht_add_unique_ulong(agent_apps_ht_by_sock, &app->node);
 730 }
 731
 732 /*
 733  * Delete agent application from the global hash table.
 734  *
 735  * rcu_read_lock() must be held by the caller.
 736  */
 737 void agent_delete_app(struct agent_app *app)
 738 {
 739         int ret;
 740         struct lttng_ht_iter iter;
 741
 742         assert(app);
 743
 744         DBG3("Agent deleting app pid: %d and sock: %d", app->pid, app->sock->fd);
 745
 746         iter.iter.node = &app->node.node;
 747         ret = lttng_ht_del(agent_apps_ht_by_sock, &iter);
 748         assert(!ret);
 749 }
 750
 751 /*
 752  * Destroy an agent application object by detaching it from its corresponding
 753  * UST app if one is connected by closing the socket. Finally, perform a
 754  * delayed memory reclaim.
 755  */
 756 void agent_destroy_app(struct agent_app *app)
 757 {
 758         assert(app);
 759
 760         if (app->sock) {
 761                 app->sock->ops->close(app->sock);
 762                 lttcomm_destroy_sock(app->sock);
 763         }
 764
 765         call_rcu(&app->node.head, destroy_app_agent_rcu);
 766 }
 767
 768 /*
 769  * Initialize an already allocated agent object.
 770  *
 771  * Return 0 on success or else a negative errno value.
 772  */
 773 int agent_init(struct agent *agt)
 774 {
 775         int ret;
 776
 777         assert(agt);
 778
 779         agt->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 780         if (!agt->events) {
 781                 ret = -ENOMEM;
 782                 goto error;
 783         }
 784         lttng_ht_node_init_u64(&agt->node, agt->domain);
 785
 786         return 0;
 787
 788 error:
 789         return ret;
 790 }
 791
 792 /*
 793  * Add agent object to the given hash table.
 794  */
 795 void agent_add(struct agent *agt, struct lttng_ht *ht)
 796 {
 797         assert(agt);
 798         assert(ht);
 799
 800         DBG3("Agent adding from domain %d", agt->domain);
 801
 802         lttng_ht_add_unique_u64(ht, &agt->node);
 803 }
 804
 805 /*
 806  * Create an agent object for the given domain.
 807  *
 808  * Return the allocated agent or NULL on error.
 809  */
 810 struct agent *agent_create(enum lttng_domain_type domain)
 811 {
 812         int ret;
 813         struct agent *agt;
 814
 815         agt = zmalloc(sizeof(struct agent));
 816         if (!agt) {
 817                 goto error;
 818         }
 819         agt->domain = domain;
 820
 821         ret = agent_init(agt);
 822         if (ret < 0) {
 823                 free(agt);
 824                 agt = NULL;
 825                 goto error;
 826         }
 827
 828 error:
 829         return agt;
 830 }
 831
 832 /*
 833  * Create a newly allocated agent event data structure.
 834  * Ownership of filter_expression is taken.
 835  *
 836  * Return a new object else NULL on error.
 837  */
 838 struct agent_event *agent_create_event(const char *name,
 839                 enum lttng_loglevel_type loglevel_type, int loglevel_value,
 840                 struct lttng_filter_bytecode *filter, char *filter_expression)
 841 {
 842         struct agent_event *event = NULL;
 843
 844         DBG3("Agent create new event with name %s, loglevel type %d and loglevel value %d",
 845                 name, loglevel_type, loglevel_value);
 846
 847         if (!name) {
 848                 ERR("Failed to create agent event; no name provided.");
 849                 goto error;
 850         }
 851
 852         event = zmalloc(sizeof(*event));
 853         if (!event) {
 854                 goto error;
 855         }
 856
 857         strncpy(event->name, name, sizeof(event->name));
 858         event->name[sizeof(event->name) - 1] = '\0';
 859         lttng_ht_node_init_str(&event->node, event->name);
 860
 861         event->loglevel_value = loglevel_value;
 862         event->loglevel_type = loglevel_type;
 863         event->filter = filter;
 864         event->filter_expression = filter_expression;
 865 error:
 866         return event;
 867 }
 868
 869 /*
 870  * Unique add of a agent event to an agent object.
 871  */
 872 void agent_add_event(struct agent_event *event, struct agent *agt)
 873 {
 874         assert(event);
 875         assert(agt);
 876         assert(agt->events);
 877
 878         DBG3("Agent adding event %s", event->name);
 879         add_unique_agent_event(agt->events, event);
 880         agt->being_used = 1;
 881 }
 882
 883 /*
 884  * Find a agent event in the given agent using name.
 885  *
 886  * RCU read side lock MUST be acquired.
 887  *
 888  * Return object if found else NULL.
 889  */
 890 struct agent_event *agent_find_event_by_name(const char *name,
 891                 struct agent *agt)
 892 {
 893         struct lttng_ht_node_str *node;
 894         struct lttng_ht_iter iter;
 895         struct lttng_ht *ht;
 896         struct agent_ht_key key;
 897
 898         assert(name);
 899         assert(agt);
 900         assert(agt->events);
 901
 902         ht = agt->events;
 903         key.name = name;
 904
 905         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 906                         ht_match_event_by_name, &key, &iter.iter);
 907         node = lttng_ht_iter_get_node_str(&iter);
 908         if (node == NULL) {
 909                 goto error;
 910         }
 911
 912         DBG3("Agent event found %s by name.", name);
 913         return caa_container_of(node, struct agent_event, node);
 914
 915 error:
 916         DBG3("Agent NOT found by name %s.", name);
 917         return NULL;
 918 }
 919
 920 /*
 921  * Find a agent event in the given agent using name and loglevel.
 922  *
 923  * RCU read side lock MUST be acquired.
 924  *
 925  * Return object if found else NULL.
 926  */
 927 struct agent_event *agent_find_event(const char *name,
 928                 enum lttng_loglevel_type loglevel_type, int loglevel_value,
 929                 struct agent *agt)
 930 {
 931         struct lttng_ht_node_str *node;
 932         struct lttng_ht_iter iter;
 933         struct lttng_ht *ht;
 934         struct agent_ht_key key;
 935
 936         assert(name);
 937         assert(agt);
 938         assert(agt->events);
 939
 940         ht = agt->events;
 941         key.name = name;
 942         key.loglevel_value = loglevel_value;
 943         key.loglevel_type = loglevel_type;
 944
 945         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 946                         ht_match_event, &key, &iter.iter);
 947         node = lttng_ht_iter_get_node_str(&iter);
 948         if (node == NULL) {
 949                 goto error;
 950         }
 951
 952         DBG3("Agent event found %s.", name);
 953         return caa_container_of(node, struct agent_event, node);
 954
 955 error:
 956         DBG3("Agent event NOT found %s.", name);
 957         return NULL;
 958 }
 959
 960 /*
 961  * Free given agent event. This event must not be globally visible at this
 962  * point (only expected to be used on failure just after event creation). After
 963  * this call, the pointer is not usable anymore.
 964  */
 965 void agent_destroy_event(struct agent_event *event)
 966 {
 967         assert(event);
 968
 969         free(event->filter);
 970         free(event->filter_expression);
 971         free(event->exclusion);
 972         free(event);
 973 }
 974
 975 /*
 976  * Destroy an agent completely.
 977  */
 978 void agent_destroy(struct agent *agt)
 979 {
 980         struct lttng_ht_node_str *node;
 981         struct lttng_ht_iter iter;
 982
 983         assert(agt);
 984
 985         DBG3("Agent destroy");
 986
 987         rcu_read_lock();
 988         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, node, node) {
 989                 int ret;
 990                 struct agent_event *event;
 991
 992                 /*
 993                  * When destroying an event, we have to try to disable it on the agent
 994                  * side so the event stops generating data. The return value is not
 995                  * important since we have to continue anyway destroying the object.
 996                  */
 997                 event = caa_container_of(node, struct agent_event, node);
 998                 (void) agent_disable_event(event, agt->domain);
 999
1000                 ret = lttng_ht_del(agt->events, &iter);
1001                 assert(!ret);
1002                 call_rcu(&node->head, destroy_event_agent_rcu);
1003         }
1004         rcu_read_unlock();
1005
1006         ht_cleanup_push(agt->events);
1007         free(agt);
1008 }
1009
1010 /*
1011  * Allocate agent_apps_ht_by_sock.
1012  */
1013 int agent_app_ht_alloc(void)
1014 {
1015         int ret = 0;
1016
1017         agent_apps_ht_by_sock = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
1018         if (!agent_apps_ht_by_sock) {
1019                 ret = -1;
1020         }
1021
1022         return ret;
1023 }
1024
1025 /*
1026  * Destroy a agent application by socket.
1027  */
1028 void agent_destroy_app_by_sock(int sock)
1029 {
1030         struct agent_app *app;
1031
1032         assert(sock >= 0);
1033
1034         /*
1035          * Not finding an application is a very important error that should NEVER
1036          * happen. The hash table deletion is ONLY done through this call when the
1037          * main sessiond thread is torn down.
1038          */
1039         rcu_read_lock();
1040         app = agent_find_app_by_sock(sock);
1041         assert(app);
1042
1043         /* RCU read side lock is assumed to be held by this function. */
1044         agent_delete_app(app);
1045
1046         /* The application is freed in a RCU call but the socket is closed here. */
1047         agent_destroy_app(app);
1048         rcu_read_unlock();
1049 }
1050
1051 /*
1052  * Clean-up the agent app hash table and destroy it.
1053  */
1054 void agent_app_ht_clean(void)
1055 {
1056         struct lttng_ht_node_ulong *node;
1057         struct lttng_ht_iter iter;
1058
1059         if (!agent_apps_ht_by_sock) {
1060                 return;
1061         }
1062         rcu_read_lock();
1063         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, node, node) {
1064                 struct agent_app *app;
1065
1066                 app = caa_container_of(node, struct agent_app, node);
1067                 agent_destroy_app_by_sock(app->sock->fd);
1068         }
1069         rcu_read_unlock();
1070
1071         lttng_ht_destroy(agent_apps_ht_by_sock);
1072 }
1073
1074 /*
1075  * Update a agent application (given socket) using the given agent.
1076  *
1077  * Note that this function is most likely to be used with a tracing session
1078  * thus the caller should make sure to hold the appropriate lock(s).
1079  */
1080 void agent_update(struct agent *agt, int sock)
1081 {
1082         int ret;
1083         struct agent_app *app;
1084         struct agent_event *event;
1085         struct lttng_ht_iter iter;
1086
1087         assert(agt);
1088         assert(sock >= 0);
1089
1090         DBG("Agent updating app socket %d", sock);
1091
1092         rcu_read_lock();
1093         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, event, node.node) {
1094                 /* Skip event if disabled. */
1095                 if (!event->enabled) {
1096                         continue;
1097                 }
1098
1099                 app = agent_find_app_by_sock(sock);
1100                 /*
1101                  * We are in the registration path thus if the application is gone,
1102                  * there is a serious code flow error.
1103                  */
1104                 assert(app);
1105
1106                 ret = enable_event(app, event);
1107                 if (ret != LTTNG_OK) {
1108                         DBG2("Agent update unable to enable event %s on app pid: %d sock %d",
1109                                         event->name, app->pid, app->sock->fd);
1110                         /* Let's try the others here and don't assume the app is dead. */
1111                         continue;
1112                 }
1113         }
1114         rcu_read_unlock();
1115 }