src/bin/lttng-sessiond/agent.c

   1 /*
   2  * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License, version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc., 51
  15  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _GNU_SOURCE
  19 #define _LGPL_SOURCE
  20 #include <assert.h>
  21 #include <urcu/uatomic.h>
  22
  23 #include <common/common.h>
  24 #include <common/sessiond-comm/agent.h>
  25
  26 #include <common/compat/endian.h>
  27
  28 #include "agent.h"
  29 #include "ust-app.h"
  30 #include "utils.h"
  31 #include "error.h"
  32
  33 #define AGENT_RET_CODE_INDEX(code) (code - AGENT_RET_CODE_SUCCESS)
  34
  35 /*
  36  * Human readable agent return code.
  37  */
  38 static const char *error_string_array[] = {
  39         [ AGENT_RET_CODE_INDEX(AGENT_RET_CODE_SUCCESS) ] = "Success",
  40         [ AGENT_RET_CODE_INDEX(AGENT_RET_CODE_INVALID) ] = "Invalid command",
  41         [ AGENT_RET_CODE_INDEX(AGENT_RET_CODE_UNKNOWN_NAME) ] = "Unknown logger name",
  42
  43         /* Last element */
  44         [ AGENT_RET_CODE_INDEX(AGENT_RET_CODE_NR) ] = "Unknown code",
  45 };
  46
  47 static
  48 void log_reply_code(uint32_t in_reply_ret_code)
  49 {
  50         int level = PRINT_DBG3;
  51         /*
  52          * reply_ret_code and in_reply_ret_code are kept separate to have a
  53          * sanitized value (used to retrieve the human readable string) and the
  54          * original value which is logged as-is.
  55          */
  56         uint32_t reply_ret_code = in_reply_ret_code;
  57
  58         if (reply_ret_code < AGENT_RET_CODE_SUCCESS ||
  59                         reply_ret_code >= AGENT_RET_CODE_NR) {
  60                 reply_ret_code = AGENT_RET_CODE_NR;
  61                 level = PRINT_ERR;
  62         }
  63
  64         LOG(level, "Agent replied with retcode: %s (%"PRIu32")",
  65                         error_string_array[AGENT_RET_CODE_INDEX(
  66                         reply_ret_code)],
  67                         in_reply_ret_code);
  68 }
  69
  70 /*
  71  * Match function for the events hash table lookup by name.
  72  */
  73 static int ht_match_event_by_name(struct cds_lfht_node *node,
  74                 const void *_key)
  75 {
  76         struct agent_event *event;
  77         const struct agent_ht_key *key;
  78
  79         assert(node);
  80         assert(_key);
  81
  82         event = caa_container_of(node, struct agent_event, node.node);
  83         key = _key;
  84
  85         /* Match 1 elements of the key: name. */
  86
  87         /* Event name */
  88         if (strncmp(event->name, key->name, sizeof(event->name)) != 0) {
  89                 goto no_match;
  90         }
  91         /* Match. */
  92         return 1;
  93
  94 no_match:
  95         return 0;
  96 }
  97
  98 /*
  99  * Match function for the events hash table lookup by name and loglevel.
 100  */
 101 static int ht_match_event(struct cds_lfht_node *node,
 102                 const void *_key)
 103 {
 104         struct agent_event *event;
 105         const struct agent_ht_key *key;
 106
 107         assert(node);
 108         assert(_key);
 109
 110         event = caa_container_of(node, struct agent_event, node.node);
 111         key = _key;
 112
 113         /* Match 2 elements of the key: name and loglevel. */
 114
 115         /* Event name */
 116         if (strncmp(event->name, key->name, sizeof(event->name)) != 0) {
 117                 goto no_match;
 118         }
 119
 120         if (event->loglevel != key->loglevel) {
 121                 if (event->loglevel_type == LTTNG_EVENT_LOGLEVEL_ALL &&
 122                                 key->loglevel == 0 && event->loglevel == -1) {
 123                         goto match;
 124                 }
 125                 goto no_match;
 126         }
 127 match:
 128         return 1;
 129
 130 no_match:
 131         return 0;
 132 }
 133
 134 /*
 135  * Add unique agent event based on the event name and loglevel.
 136  */
 137 static void add_unique_agent_event(struct lttng_ht *ht,
 138                 struct agent_event *event)
 139 {
 140         struct cds_lfht_node *node_ptr;
 141         struct agent_ht_key key;
 142
 143         assert(ht);
 144         assert(ht->ht);
 145         assert(event);
 146
 147         key.name = event->name;
 148         key.loglevel = event->loglevel;
 149
 150         node_ptr = cds_lfht_add_unique(ht->ht,
 151                         ht->hash_fct(event->node.key, lttng_ht_seed),
 152                         ht_match_event, &key, &event->node.node);
 153         assert(node_ptr == &event->node.node);
 154 }
 155
 156 /*
 157  * URCU delayed agent event reclaim.
 158  */
 159 static void destroy_event_agent_rcu(struct rcu_head *head)
 160 {
 161         struct lttng_ht_node_str *node =
 162                 caa_container_of(head, struct lttng_ht_node_str, head);
 163         struct agent_event *event =
 164                 caa_container_of(node, struct agent_event, node);
 165
 166         free(event);
 167 }
 168
 169 /*
 170  * URCU delayed agent app reclaim.
 171  */
 172 static void destroy_app_agent_rcu(struct rcu_head *head)
 173 {
 174         struct lttng_ht_node_ulong *node =
 175                 caa_container_of(head, struct lttng_ht_node_ulong, head);
 176         struct agent_app *app =
 177                 caa_container_of(node, struct agent_app, node);
 178
 179         free(app);
 180 }
 181
 182 /*
 183  * Communication with the agent. Send the message header to the given socket in
 184  * big endian.
 185  *
 186  * Return 0 on success or else a negative errno message of sendmsg() op.
 187  */
 188 static int send_header(struct lttcomm_sock *sock, uint64_t data_size,
 189                 uint32_t cmd, uint32_t cmd_version)
 190 {
 191         int ret;
 192         ssize_t size;
 193         struct lttcomm_agent_hdr msg;
 194
 195         assert(sock);
 196
 197         memset(&msg, 0, sizeof(msg));
 198         msg.data_size = htobe64(data_size);
 199         msg.cmd = htobe32(cmd);
 200         msg.cmd_version = htobe32(cmd_version);
 201
 202         size = sock->ops->sendmsg(sock, &msg, sizeof(msg), 0);
 203         if (size < sizeof(msg)) {
 204                 ret = -errno;
 205                 goto error;
 206         }
 207         ret = 0;
 208
 209 error:
 210         return ret;
 211 }
 212
 213 /*
 214  * Communication call with the agent. Send the payload to the given socket. The
 215  * header MUST be sent prior to this call.
 216  *
 217  * Return 0 on success or else a negative errno value of sendmsg() op.
 218  */
 219 static int send_payload(struct lttcomm_sock *sock, void *data,
 220                 size_t size)
 221 {
 222         int ret;
 223         ssize_t len;
 224
 225         assert(sock);
 226         assert(data);
 227
 228         len = sock->ops->sendmsg(sock, data, size, 0);
 229         if (len < size) {
 230                 ret = -errno;
 231                 goto error;
 232         }
 233         ret = 0;
 234
 235 error:
 236         return ret;
 237 }
 238
 239 /*
 240  * Communication call with the agent. Receive reply from the agent using the
 241  * given socket.
 242  *
 243  * Return 0 on success or else a negative errno value from recvmsg() op.
 244  */
 245 static int recv_reply(struct lttcomm_sock *sock, void *buf, size_t size)
 246 {
 247         int ret;
 248         ssize_t len;
 249
 250         assert(sock);
 251         assert(buf);
 252
 253         len = sock->ops->recvmsg(sock, buf, size, 0);
 254         if (len < size) {
 255                 ret = -errno;
 256                 goto error;
 257         }
 258         ret = 0;
 259
 260 error:
 261         return ret;
 262 }
 263
 264 /*
 265  * Internal event listing for a given app. Populate events.
 266  *
 267  * Return number of element in the list or else a negative LTTNG_ERR* code.
 268  * On success, the caller is responsible for freeing the memory
 269  * allocated for "events".
 270  */
 271 static ssize_t list_events(struct agent_app *app, struct lttng_event **events)
 272 {
 273         int ret, i, len = 0, offset = 0;
 274         uint32_t nb_event;
 275         size_t data_size;
 276         uint32_t reply_ret_code;
 277         struct lttng_event *tmp_events = NULL;
 278         struct lttcomm_agent_list_reply *reply = NULL;
 279         struct lttcomm_agent_list_reply_hdr reply_hdr;
 280
 281         assert(app);
 282         assert(app->sock);
 283         assert(events);
 284
 285         DBG2("Agent listing events for app pid: %d and socket %d", app->pid,
 286                         app->sock->fd);
 287
 288         ret = send_header(app->sock, 0, AGENT_CMD_LIST, 0);
 289         if (ret < 0) {
 290                 goto error_io;
 291         }
 292
 293         /* Get list header so we know how much we'll receive. */
 294         ret = recv_reply(app->sock, &reply_hdr, sizeof(reply_hdr));
 295         if (ret < 0) {
 296                 goto error_io;
 297         }
 298
 299         reply_ret_code = be32toh(reply_hdr.ret_code);
 300         log_reply_code(reply_ret_code);
 301         switch (reply_ret_code) {
 302         case AGENT_RET_CODE_SUCCESS:
 303                 data_size = be32toh(reply_hdr.data_size) + sizeof(*reply);
 304                 break;
 305         default:
 306                 ERR("Agent returned an unknown code: %" PRIu32,
 307                                 be32toh(reply_hdr.ret_code));
 308                 ret = LTTNG_ERR_FATAL;
 309                 goto error;
 310         }
 311
 312         reply = zmalloc(data_size);
 313         if (!reply) {
 314                 ret = LTTNG_ERR_NOMEM;
 315                 goto error;
 316         }
 317
 318         /* Get the list with the appropriate data size. */
 319         ret = recv_reply(app->sock, reply, data_size);
 320         if (ret < 0) {
 321                 goto error_io;
 322         }
 323
 324         nb_event = be32toh(reply->nb_event);
 325         tmp_events = zmalloc(sizeof(*tmp_events) * nb_event);
 326         if (!tmp_events) {
 327                 ret = LTTNG_ERR_NOMEM;
 328                 goto error;
 329         }
 330
 331         for (i = 0; i < nb_event; i++) {
 332                 offset += len;
 333                 strncpy(tmp_events[i].name, reply->payload + offset,
 334                                 sizeof(tmp_events[i].name));
 335                 tmp_events[i].pid = app->pid;
 336                 tmp_events[i].enabled = -1;
 337                 len = strlen(reply->payload + offset) + 1;
 338         }
 339
 340         *events = tmp_events;
 341
 342         free(reply);
 343         return nb_event;
 344
 345 error_io:
 346         ret = LTTNG_ERR_UST_LIST_FAIL;
 347 error:
 348         free(reply);
 349         free(tmp_events);
 350         return -ret;
 351
 352 }
 353
 354 /*
 355  * Internal enable agent event on a agent application. This function
 356  * communicates with the agent to enable a given event.
 357  *
 358  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 359  */
 360 static int enable_event(struct agent_app *app, struct agent_event *event)
 361 {
 362         int ret;
 363         uint64_t data_size;
 364         uint32_t reply_ret_code;
 365         struct lttcomm_agent_enable msg;
 366         struct lttcomm_agent_generic_reply reply;
 367
 368         assert(app);
 369         assert(app->sock);
 370         assert(event);
 371
 372         DBG2("Agent enabling event %s for app pid: %d and socket %d", event->name,
 373                         app->pid, app->sock->fd);
 374
 375         data_size = sizeof(msg);
 376
 377         ret = send_header(app->sock, data_size, AGENT_CMD_ENABLE, 0);
 378         if (ret < 0) {
 379                 goto error_io;
 380         }
 381
 382         memset(&msg, 0, sizeof(msg));
 383         msg.loglevel = event->loglevel;
 384         msg.loglevel_type = event->loglevel_type;
 385         strncpy(msg.name, event->name, sizeof(msg.name));
 386         ret = send_payload(app->sock, &msg, sizeof(msg));
 387         if (ret < 0) {
 388                 goto error_io;
 389         }
 390
 391         ret = recv_reply(app->sock, &reply, sizeof(reply));
 392         if (ret < 0) {
 393                 goto error_io;
 394         }
 395
 396         reply_ret_code = be32toh(reply.ret_code);
 397         log_reply_code(reply_ret_code);
 398         switch (reply_ret_code) {
 399         case AGENT_RET_CODE_SUCCESS:
 400                 break;
 401         case AGENT_RET_CODE_UNKNOWN_NAME:
 402                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 403                 goto error;
 404         default:
 405                 ERR("Agent returned an unknown code: %" PRIu32,
 406                                 be32toh(reply.ret_code));
 407                 ret = LTTNG_ERR_FATAL;
 408                 goto error;
 409         }
 410
 411         return LTTNG_OK;
 412
 413 error_io:
 414         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 415 error:
 416         return ret;
 417 }
 418
 419 /*
 420  * Internal disable agent event call on a agent application. This function
 421  * communicates with the agent to disable a given event.
 422  *
 423  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 424  */
 425 static int disable_event(struct agent_app *app, struct agent_event *event)
 426 {
 427         int ret;
 428         uint64_t data_size;
 429         struct lttcomm_agent_disable msg;
 430         struct lttcomm_agent_generic_reply reply;
 431
 432         assert(app);
 433         assert(app->sock);
 434         assert(event);
 435
 436         DBG2("Agent disabling event %s for app pid: %d and socket %d", event->name,
 437                         app->pid, app->sock->fd);
 438
 439         data_size = sizeof(msg);
 440
 441         ret = send_header(app->sock, data_size, AGENT_CMD_DISABLE, 0);
 442         if (ret < 0) {
 443                 goto error_io;
 444         }
 445
 446         memset(&msg, 0, sizeof(msg));
 447         strncpy(msg.name, event->name, sizeof(msg.name));
 448         ret = send_payload(app->sock, &msg, sizeof(msg));
 449         if (ret < 0) {
 450                 goto error_io;
 451         }
 452
 453         ret = recv_reply(app->sock, &reply, sizeof(reply));
 454         if (ret < 0) {
 455                 goto error_io;
 456         }
 457
 458         switch (be32toh(reply.ret_code)) {
 459         case AGENT_RET_CODE_SUCCESS:
 460                 break;
 461         case AGENT_RET_CODE_UNKNOWN_NAME:
 462                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 463                 goto error;
 464         default:
 465                 ERR("Agent returned an unknown code: %" PRIu32,
 466                                 be32toh(reply.ret_code));
 467                 ret = LTTNG_ERR_FATAL;
 468                 goto error;
 469         }
 470
 471         return LTTNG_OK;
 472
 473 error_io:
 474         ret = LTTNG_ERR_UST_DISABLE_FAIL;
 475 error:
 476         return ret;
 477 }
 478
 479 /*
 480  * Send back the registration DONE command to a given agent application.
 481  *
 482  * Return 0 on success or else a negative value.
 483  */
 484 int agent_send_registration_done(struct agent_app *app)
 485 {
 486         assert(app);
 487         assert(app->sock);
 488
 489         DBG("Agent sending registration done to app socket %d", app->sock->fd);
 490
 491         return send_header(app->sock, 0, AGENT_CMD_REG_DONE, 0);
 492 }
 493
 494 /*
 495  * Enable agent event on every agent applications registered with the session
 496  * daemon.
 497  *
 498  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 499  */
 500 int agent_enable_event(struct agent_event *event,
 501                 enum lttng_domain_type domain)
 502 {
 503         int ret;
 504         struct agent_app *app;
 505         struct lttng_ht_iter iter;
 506
 507         assert(event);
 508
 509         rcu_read_lock();
 510
 511         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 512                         node.node) {
 513                 if (app->domain != domain) {
 514                         continue;
 515                 }
 516
 517                 /* Enable event on agent application through TCP socket. */
 518                 ret = enable_event(app, event);
 519                 if (ret != LTTNG_OK) {
 520                         goto error;
 521                 }
 522         }
 523
 524         event->enabled = 1;
 525         ret = LTTNG_OK;
 526
 527 error:
 528         rcu_read_unlock();
 529         return ret;
 530 }
 531
 532 /*
 533  * Disable agent event on every agent applications registered with the session
 534  * daemon.
 535  *
 536  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 537  */
 538 int agent_disable_event(struct agent_event *event,
 539                 enum lttng_domain_type domain)
 540 {
 541         int ret = LTTNG_OK;
 542         struct agent_app *app;
 543         struct lttng_ht_iter iter;
 544
 545         assert(event);
 546         if (!event->enabled) {
 547                 goto end;
 548         }
 549
 550         rcu_read_lock();
 551
 552         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 553                         node.node) {
 554                 if (app->domain != domain) {
 555                         continue;
 556                 }
 557
 558                 /* Enable event on agent application through TCP socket. */
 559                 ret = disable_event(app, event);
 560                 if (ret != LTTNG_OK) {
 561                         goto error;
 562                 }
 563         }
 564
 565         event->enabled = 0;
 566
 567 error:
 568         rcu_read_unlock();
 569 end:
 570         return ret;
 571 }
 572
 573 /*
 574  * Ask every agent for the list of possible event. Events is allocated with the
 575  * events of every agent application.
 576  *
 577  * Return the number of events or else a negative value.
 578  */
 579 int agent_list_events(struct lttng_event **events,
 580                 enum lttng_domain_type domain)
 581 {
 582         int ret;
 583         size_t nbmem, count = 0;
 584         struct agent_app *app;
 585         struct lttng_event *tmp_events = NULL;
 586         struct lttng_ht_iter iter;
 587
 588         assert(events);
 589
 590         DBG2("Agent listing events for domain %d", domain);
 591
 592         nbmem = UST_APP_EVENT_LIST_SIZE;
 593         tmp_events = zmalloc(nbmem * sizeof(*tmp_events));
 594         if (!tmp_events) {
 595                 PERROR("zmalloc agent list events");
 596                 ret = -ENOMEM;
 597                 goto error;
 598         }
 599
 600         rcu_read_lock();
 601         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 602                         node.node) {
 603                 ssize_t nb_ev;
 604                 struct lttng_event *agent_events;
 605
 606                 /* Skip domain not asked by the list. */
 607                 if (app->domain != domain) {
 608                         continue;
 609                 }
 610
 611                 nb_ev = list_events(app, &agent_events);
 612                 if (nb_ev < 0) {
 613                         ret = nb_ev;
 614                         goto error_unlock;
 615                 }
 616
 617                 if (count + nb_ev > nbmem) {
 618                         /* In case the realloc fails, we free the memory */
 619                         struct lttng_event *new_tmp_events;
 620                         size_t new_nbmem;
 621
 622                         new_nbmem = max_t(size_t, count + nb_ev, nbmem << 1);
 623                         DBG2("Reallocating agent event list from %zu to %zu entries",
 624                                         nbmem, new_nbmem);
 625                         new_tmp_events = realloc(tmp_events,
 626                                 new_nbmem * sizeof(*new_tmp_events));
 627                         if (!new_tmp_events) {
 628                                 PERROR("realloc agent events");
 629                                 ret = -ENOMEM;
 630                                 free(agent_events);
 631                                 goto error_unlock;
 632                         }
 633                         /* Zero the new memory */
 634                         memset(new_tmp_events + nbmem, 0,
 635                                 (new_nbmem - nbmem) * sizeof(*new_tmp_events));
 636                         nbmem = new_nbmem;
 637                         tmp_events = new_tmp_events;
 638                 }
 639                 memcpy(tmp_events + count, agent_events,
 640                         nb_ev * sizeof(*tmp_events));
 641                 free(agent_events);
 642                 count += nb_ev;
 643         }
 644         rcu_read_unlock();
 645
 646         ret = count;
 647         *events = tmp_events;
 648         return ret;
 649
 650 error_unlock:
 651         rcu_read_unlock();
 652 error:
 653         free(tmp_events);
 654         return ret;
 655 }
 656
 657 /*
 658  * Create a agent app object using the given PID.
 659  *
 660  * Return newly allocated object or else NULL on error.
 661  */
 662 struct agent_app *agent_create_app(pid_t pid, enum lttng_domain_type domain,
 663                 struct lttcomm_sock *sock)
 664 {
 665         struct agent_app *app;
 666
 667         assert(sock);
 668
 669         app = zmalloc(sizeof(*app));
 670         if (!app) {
 671                 PERROR("zmalloc agent create");
 672                 goto error;
 673         }
 674
 675         app->pid = pid;
 676         app->domain = domain;
 677         app->sock = sock;
 678         lttng_ht_node_init_ulong(&app->node, (unsigned long) app->sock->fd);
 679
 680 error:
 681         return app;
 682 }
 683
 684 /*
 685  * Lookup agent app by socket in the global hash table.
 686  *
 687  * RCU read side lock MUST be acquired.
 688  *
 689  * Return object if found else NULL.
 690  */
 691 struct agent_app *agent_find_app_by_sock(int sock)
 692 {
 693         struct lttng_ht_node_ulong *node;
 694         struct lttng_ht_iter iter;
 695         struct agent_app *app;
 696
 697         assert(sock >= 0);
 698
 699         lttng_ht_lookup(agent_apps_ht_by_sock, (void *)((unsigned long) sock), &iter);
 700         node = lttng_ht_iter_get_node_ulong(&iter);
 701         if (node == NULL) {
 702                 goto error;
 703         }
 704         app = caa_container_of(node, struct agent_app, node);
 705
 706         DBG3("Agent app pid %d found by sock %d.", app->pid, sock);
 707         return app;
 708
 709 error:
 710         DBG3("Agent app NOT found by sock %d.", sock);
 711         return NULL;
 712 }
 713
 714 /*
 715  * Add agent application object to the global hash table.
 716  */
 717 void agent_add_app(struct agent_app *app)
 718 {
 719         assert(app);
 720
 721         DBG3("Agent adding app sock: %d and pid: %d to ht", app->sock->fd, app->pid);
 722
 723         rcu_read_lock();
 724         lttng_ht_add_unique_ulong(agent_apps_ht_by_sock, &app->node);
 725         rcu_read_unlock();
 726 }
 727
 728 /*
 729  * Delete agent application from the global hash table.
 730  *
 731  * rcu_read_lock() must be held by the caller.
 732  */
 733 void agent_delete_app(struct agent_app *app)
 734 {
 735         int ret;
 736         struct lttng_ht_iter iter;
 737
 738         assert(app);
 739
 740         DBG3("Agent deleting app pid: %d and sock: %d", app->pid, app->sock->fd);
 741
 742         iter.iter.node = &app->node.node;
 743         ret = lttng_ht_del(agent_apps_ht_by_sock, &iter);
 744         assert(!ret);
 745 }
 746
 747 /*
 748  * Destroy an agent application object by detaching it from its corresponding
 749  * UST app if one is connected by closing the socket. Finally, perform a
 750  * delayed memory reclaim.
 751  */
 752 void agent_destroy_app(struct agent_app *app)
 753 {
 754         assert(app);
 755
 756         if (app->sock) {
 757                 app->sock->ops->close(app->sock);
 758                 lttcomm_destroy_sock(app->sock);
 759         }
 760
 761         call_rcu(&app->node.head, destroy_app_agent_rcu);
 762 }
 763
 764 /*
 765  * Initialize an already allocated agent object.
 766  *
 767  * Return 0 on success or else a negative errno value.
 768  */
 769 int agent_init(struct agent *agt)
 770 {
 771         int ret;
 772
 773         assert(agt);
 774
 775         agt->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 776         if (!agt->events) {
 777                 ret = -ENOMEM;
 778                 goto error;
 779         }
 780         lttng_ht_node_init_u64(&agt->node, agt->domain);
 781
 782         return 0;
 783
 784 error:
 785         return ret;
 786 }
 787
 788 /*
 789  * Add agent object to the given hash table.
 790  */
 791 void agent_add(struct agent *agt, struct lttng_ht *ht)
 792 {
 793         assert(agt);
 794         assert(ht);
 795
 796         DBG3("Agent adding from domain %d", agt->domain);
 797
 798         rcu_read_lock();
 799         lttng_ht_add_unique_u64(ht, &agt->node);
 800         rcu_read_unlock();
 801 }
 802
 803 /*
 804  * Create an agent object for the given domain.
 805  *
 806  * Return the allocated agent or NULL on error.
 807  */
 808 struct agent *agent_create(enum lttng_domain_type domain)
 809 {
 810         int ret;
 811         struct agent *agt;
 812
 813         agt = zmalloc(sizeof(*agt));
 814         if (!agt) {
 815                 goto error;
 816         }
 817         agt->domain = domain;
 818
 819         ret = agent_init(agt);
 820         if (ret < 0) {
 821                 free(agt);
 822                 agt = NULL;
 823                 goto error;
 824         }
 825
 826 error:
 827         return agt;
 828 }
 829
 830 /*
 831  * Create a newly allocated agent event data structure. If name is valid, it's
 832  * copied into the created event.
 833  *
 834  * Return a new object else NULL on error.
 835  */
 836 struct agent_event *agent_create_event(const char *name,
 837                 struct lttng_filter_bytecode *filter)
 838 {
 839         struct agent_event *event;
 840
 841         DBG3("Agent create new event with name %s", name);
 842
 843         event = zmalloc(sizeof(*event));
 844         if (!event) {
 845                 goto error;
 846         }
 847
 848         if (name) {
 849                 strncpy(event->name, name, sizeof(event->name));
 850                 event->name[sizeof(event->name) - 1] = '\0';
 851                 lttng_ht_node_init_str(&event->node, event->name);
 852         }
 853
 854         if (filter) {
 855                 event->filter = filter;
 856         }
 857
 858 error:
 859         return event;
 860 }
 861
 862 /*
 863  * Unique add of a agent event to an agent object.
 864  */
 865 void agent_add_event(struct agent_event *event, struct agent *agt)
 866 {
 867         assert(event);
 868         assert(agt);
 869         assert(agt->events);
 870
 871         DBG3("Agent adding event %s", event->name);
 872
 873         rcu_read_lock();
 874         add_unique_agent_event(agt->events, event);
 875         rcu_read_unlock();
 876         agt->being_used = 1;
 877 }
 878
 879 /*
 880  * Find a agent event in the given agent using name.
 881  *
 882  * RCU read side lock MUST be acquired.
 883  *
 884  * Return object if found else NULL.
 885  */
 886 struct agent_event *agent_find_event_by_name(const char *name,
 887                 struct agent *agt)
 888 {
 889         struct lttng_ht_node_str *node;
 890         struct lttng_ht_iter iter;
 891         struct lttng_ht *ht;
 892         struct agent_ht_key key;
 893
 894         assert(name);
 895         assert(agt);
 896         assert(agt->events);
 897
 898         ht = agt->events;
 899         key.name = name;
 900
 901         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 902                         ht_match_event_by_name, &key, &iter.iter);
 903         node = lttng_ht_iter_get_node_str(&iter);
 904         if (node == NULL) {
 905                 goto error;
 906         }
 907
 908         DBG3("Agent event found %s by name.", name);
 909         return caa_container_of(node, struct agent_event, node);
 910
 911 error:
 912         DBG3("Agent NOT found by name %s.", name);
 913         return NULL;
 914 }
 915
 916 /*
 917  * Find a agent event in the given agent using name and loglevel.
 918  *
 919  * RCU read side lock MUST be acquired.
 920  *
 921  * Return object if found else NULL.
 922  */
 923 struct agent_event *agent_find_event(const char *name, int loglevel,
 924                 struct agent *agt)
 925 {
 926         struct lttng_ht_node_str *node;
 927         struct lttng_ht_iter iter;
 928         struct lttng_ht *ht;
 929         struct agent_ht_key key;
 930
 931         assert(name);
 932         assert(agt);
 933         assert(agt->events);
 934
 935         ht = agt->events;
 936         key.name = name;
 937         key.loglevel = loglevel;
 938
 939         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 940                         ht_match_event, &key, &iter.iter);
 941         node = lttng_ht_iter_get_node_str(&iter);
 942         if (node == NULL) {
 943                 goto error;
 944         }
 945
 946         DBG3("Agent event found %s.", name);
 947         return caa_container_of(node, struct agent_event, node);
 948
 949 error:
 950         DBG3("Agent event NOT found %s.", name);
 951         return NULL;
 952 }
 953
 954 /*
 955  * Free given agent event. This event must not be globally visible at this
 956  * point (only expected to be used on failure just after event creation). After
 957  * this call, the pointer is not usable anymore.
 958  */
 959 void agent_destroy_event(struct agent_event *event)
 960 {
 961         assert(event);
 962
 963         free(event->filter);
 964         free(event);
 965 }
 966
 967 /*
 968  * Destroy an agent completely. Note that the given pointer is NOT freed
 969  * thus a reference to static or stack data can be passed to this function.
 970  */
 971 void agent_destroy(struct agent *agt)
 972 {
 973         struct lttng_ht_node_str *node;
 974         struct lttng_ht_iter iter;
 975
 976         assert(agt);
 977
 978         DBG3("Agent destroy");
 979
 980         /*
 981          * Just ignore if no events hash table exists. This is possible if for
 982          * instance an agent object was allocated but not initialized.
 983          */
 984         if (!agt->events) {
 985                 return;
 986         }
 987
 988         rcu_read_lock();
 989         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, node, node) {
 990                 int ret;
 991                 struct agent_event *event;
 992
 993                 /*
 994                  * When destroying an event, we have to try to disable it on the agent
 995                  * side so the event stops generating data. The return value is not
 996                  * important since we have to continue anyway destroying the object.
 997                  */
 998                 event = caa_container_of(node, struct agent_event, node);
 999                 (void) agent_disable_event(event, agt->domain);
1000
1001                 ret = lttng_ht_del(agt->events, &iter);
1002                 assert(!ret);
1003                 call_rcu(&node->head, destroy_event_agent_rcu);
1004         }
1005         rcu_read_unlock();
1006
1007         ht_cleanup_push(agt->events);
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 }