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 _LGPL_SOURCE
  19 #include <assert.h>
  20 #include <urcu/uatomic.h>
  21
  22 #include <common/common.h>
  23 #include <common/sessiond-comm/agent.h>
  24
  25 #include <common/compat/endian.h>
  26
  27 #include "agent.h"
  28 #include "ust-app.h"
  29 #include "utils.h"
  30 #include "error.h"
  31
  32 #define AGENT_RET_CODE_INDEX(code) (code - AGENT_RET_CODE_SUCCESS)
  33
  34 /*
  35  * Human readable agent return code.
  36  */
  37 static const char *error_string_array[] = {
  38         [ AGENT_RET_CODE_INDEX(AGENT_RET_CODE_SUCCESS) ] = "Success",
  39         [ AGENT_RET_CODE_INDEX(AGENT_RET_CODE_INVALID) ] = "Invalid command",
  40         [ AGENT_RET_CODE_INDEX(AGENT_RET_CODE_UNKNOWN_NAME) ] = "Unknown logger name",
  41
  42         /* Last element */
  43         [ AGENT_RET_CODE_INDEX(AGENT_RET_CODE_NR) ] = "Unknown code",
  44 };
  45
  46 static
  47 void log_reply_code(uint32_t in_reply_ret_code)
  48 {
  49         int level = PRINT_DBG3;
  50         /*
  51          * reply_ret_code and in_reply_ret_code are kept separate to have a
  52          * sanitized value (used to retrieve the human readable string) and the
  53          * original value which is logged as-is.
  54          */
  55         uint32_t reply_ret_code = in_reply_ret_code;
  56
  57         if (reply_ret_code < AGENT_RET_CODE_SUCCESS ||
  58                         reply_ret_code >= AGENT_RET_CODE_NR) {
  59                 reply_ret_code = AGENT_RET_CODE_NR;
  60                 level = PRINT_ERR;
  61         }
  62
  63         LOG(level, "Agent replied with retcode: %s (%"PRIu32")",
  64                         error_string_array[AGENT_RET_CODE_INDEX(
  65                         reply_ret_code)],
  66                         in_reply_ret_code);
  67 }
  68
  69 /*
  70  * Match function for the events hash table lookup by name.
  71  */
  72 static int ht_match_event_by_name(struct cds_lfht_node *node,
  73                 const void *_key)
  74 {
  75         struct agent_event *event;
  76         const struct agent_ht_key *key;
  77
  78         assert(node);
  79         assert(_key);
  80
  81         event = caa_container_of(node, struct agent_event, node.node);
  82         key = _key;
  83
  84         /* Match 1 elements of the key: name. */
  85
  86         /* Event name */
  87         if (strncmp(event->name, key->name, sizeof(event->name)) != 0) {
  88                 goto no_match;
  89         }
  90         /* Match. */
  91         return 1;
  92
  93 no_match:
  94         return 0;
  95 }
  96
  97 /*
  98  * Match function for the events hash table lookup by name and loglevel.
  99  */
 100 static int ht_match_event(struct cds_lfht_node *node,
 101                 const void *_key)
 102 {
 103         struct agent_event *event;
 104         const struct agent_ht_key *key;
 105         int ll_match;
 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         ll_match = loglevels_match(event->loglevel_type,
 122                 event->loglevel_value, key->loglevel_type,
 123                 key->loglevel_value, LTTNG_EVENT_LOGLEVEL_ALL);
 124
 125         if (!ll_match) {
 126                 goto no_match;
 127         }
 128
 129         return 1;
 130
 131 no_match:
 132         return 0;
 133 }
 134
 135 /*
 136  * Add unique agent event based on the event name and loglevel.
 137  */
 138 static void add_unique_agent_event(struct lttng_ht *ht,
 139                 struct agent_event *event)
 140 {
 141         struct cds_lfht_node *node_ptr;
 142         struct agent_ht_key key;
 143
 144         assert(ht);
 145         assert(ht->ht);
 146         assert(event);
 147
 148         key.name = event->name;
 149         key.loglevel_value = event->loglevel_value;
 150         key.loglevel_type = event->loglevel_type;
 151
 152         node_ptr = cds_lfht_add_unique(ht->ht,
 153                         ht->hash_fct(event->node.key, lttng_ht_seed),
 154                         ht_match_event, &key, &event->node.node);
 155         assert(node_ptr == &event->node.node);
 156 }
 157
 158 /*
 159  * URCU delayed agent event reclaim.
 160  */
 161 static void destroy_event_agent_rcu(struct rcu_head *head)
 162 {
 163         struct lttng_ht_node_str *node =
 164                 caa_container_of(head, struct lttng_ht_node_str, head);
 165         struct agent_event *event =
 166                 caa_container_of(node, struct agent_event, node);
 167
 168         agent_destroy_event(event);
 169 }
 170
 171 /*
 172  * URCU delayed agent app reclaim.
 173  */
 174 static void destroy_app_agent_rcu(struct rcu_head *head)
 175 {
 176         struct lttng_ht_node_ulong *node =
 177                 caa_container_of(head, struct lttng_ht_node_ulong, head);
 178         struct agent_app *app =
 179                 caa_container_of(node, struct agent_app, node);
 180
 181         free(app);
 182 }
 183
 184 /*
 185  * Communication with the agent. Send the message header to the given socket in
 186  * big endian.
 187  *
 188  * Return 0 on success or else a negative errno message of sendmsg() op.
 189  */
 190 static int send_header(struct lttcomm_sock *sock, uint64_t data_size,
 191                 uint32_t cmd, uint32_t cmd_version)
 192 {
 193         int ret;
 194         ssize_t size;
 195         struct lttcomm_agent_hdr msg;
 196
 197         assert(sock);
 198
 199         memset(&msg, 0, sizeof(msg));
 200         msg.data_size = htobe64(data_size);
 201         msg.cmd = htobe32(cmd);
 202         msg.cmd_version = htobe32(cmd_version);
 203
 204         size = sock->ops->sendmsg(sock, &msg, sizeof(msg), 0);
 205         if (size < sizeof(msg)) {
 206                 ret = -errno;
 207                 goto error;
 208         }
 209         ret = 0;
 210
 211 error:
 212         return ret;
 213 }
 214
 215 /*
 216  * Communication call with the agent. Send the payload to the given socket. The
 217  * header MUST be sent prior to this call.
 218  *
 219  * Return 0 on success or else a negative errno value of sendmsg() op.
 220  */
 221 static int send_payload(struct lttcomm_sock *sock, void *data,
 222                 size_t size)
 223 {
 224         int ret;
 225         ssize_t len;
 226
 227         assert(sock);
 228         assert(data);
 229
 230         len = sock->ops->sendmsg(sock, data, size, 0);
 231         if (len < size) {
 232                 ret = -errno;
 233                 goto error;
 234         }
 235         ret = 0;
 236
 237 error:
 238         return ret;
 239 }
 240
 241 /*
 242  * Communication call with the agent. Receive reply from the agent using the
 243  * given socket.
 244  *
 245  * Return 0 on success or else a negative errno value from recvmsg() op.
 246  */
 247 static int recv_reply(struct lttcomm_sock *sock, void *buf, size_t size)
 248 {
 249         int ret;
 250         ssize_t len;
 251
 252         assert(sock);
 253         assert(buf);
 254
 255         len = sock->ops->recvmsg(sock, buf, size, 0);
 256         if (len < size) {
 257                 ret = -errno;
 258                 goto error;
 259         }
 260         ret = 0;
 261
 262 error:
 263         return ret;
 264 }
 265
 266 /*
 267  * Internal event listing for a given app. Populate events.
 268  *
 269  * Return number of element in the list or else a negative LTTNG_ERR* code.
 270  * On success, the caller is responsible for freeing the memory
 271  * allocated for "events".
 272  */
 273 static ssize_t list_events(struct agent_app *app, struct lttng_event **events)
 274 {
 275         int ret, i, len = 0, offset = 0;
 276         uint32_t nb_event;
 277         size_t data_size;
 278         uint32_t reply_ret_code;
 279         struct lttng_event *tmp_events = NULL;
 280         struct lttcomm_agent_list_reply *reply = NULL;
 281         struct lttcomm_agent_list_reply_hdr reply_hdr;
 282
 283         assert(app);
 284         assert(app->sock);
 285         assert(events);
 286
 287         DBG2("Agent listing events for app pid: %d and socket %d", app->pid,
 288                         app->sock->fd);
 289
 290         ret = send_header(app->sock, 0, AGENT_CMD_LIST, 0);
 291         if (ret < 0) {
 292                 goto error_io;
 293         }
 294
 295         /* Get list header so we know how much we'll receive. */
 296         ret = recv_reply(app->sock, &reply_hdr, sizeof(reply_hdr));
 297         if (ret < 0) {
 298                 goto error_io;
 299         }
 300
 301         reply_ret_code = be32toh(reply_hdr.ret_code);
 302         log_reply_code(reply_ret_code);
 303         switch (reply_ret_code) {
 304         case AGENT_RET_CODE_SUCCESS:
 305                 data_size = be32toh(reply_hdr.data_size) + sizeof(*reply);
 306                 break;
 307         default:
 308                 ret = LTTNG_ERR_UNK;
 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         char *bytes_to_send;
 364         uint64_t data_size;
 365         size_t filter_expression_length;
 366         uint32_t reply_ret_code;
 367         struct lttcomm_agent_enable msg;
 368         struct lttcomm_agent_generic_reply reply;
 369
 370         assert(app);
 371         assert(app->sock);
 372         assert(event);
 373
 374         DBG2("Agent enabling event %s for app pid: %d and socket %d", event->name,
 375                         app->pid, app->sock->fd);
 376
 377         /*
 378          * Calculate the payload's size, which is the fixed-size struct followed
 379          * by the variable-length filter expression (+1 for the ending \0).
 380          */
 381         if (!event->filter_expression) {
 382                 filter_expression_length = 0;
 383         } else {
 384                 filter_expression_length = strlen(event->filter_expression) + 1;
 385         }
 386         data_size = sizeof(msg) + filter_expression_length;
 387
 388         ret = send_header(app->sock, data_size, AGENT_CMD_ENABLE, 0);
 389         if (ret < 0) {
 390                 goto error_io;
 391         }
 392
 393         memset(&msg, 0, sizeof(msg));
 394         msg.loglevel_value = event->loglevel_value;
 395         msg.loglevel_type = event->loglevel_type;
 396         strncpy(msg.name, event->name, sizeof(msg.name));
 397         msg.filter_expression_length = filter_expression_length;
 398
 399         bytes_to_send = zmalloc(data_size);
 400         if (!bytes_to_send) {
 401                 ret = LTTNG_ERR_NOMEM;
 402                 goto error;
 403         }
 404
 405         memcpy(bytes_to_send, &msg, sizeof(msg));
 406         if (filter_expression_length > 0) {
 407                 memcpy(bytes_to_send + sizeof(msg), event->filter_expression,
 408                                 filter_expression_length);
 409         }
 410
 411         ret = send_payload(app->sock, bytes_to_send, data_size);
 412         free(bytes_to_send);
 413         if (ret < 0) {
 414                 goto error_io;
 415         }
 416
 417         ret = recv_reply(app->sock, &reply, sizeof(reply));
 418         if (ret < 0) {
 419                 goto error_io;
 420         }
 421
 422         reply_ret_code = be32toh(reply.ret_code);
 423         log_reply_code(reply_ret_code);
 424         switch (reply_ret_code) {
 425         case AGENT_RET_CODE_SUCCESS:
 426                 break;
 427         case AGENT_RET_CODE_UNKNOWN_NAME:
 428                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 429                 goto error;
 430         default:
 431                 ret = LTTNG_ERR_UNK;
 432                 goto error;
 433         }
 434
 435         return LTTNG_OK;
 436
 437 error_io:
 438         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 439 error:
 440         return ret;
 441 }
 442
 443 /*
 444  * Internal disable agent event call on a agent application. This function
 445  * communicates with the agent to disable a given event.
 446  *
 447  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 448  */
 449 static int disable_event(struct agent_app *app, struct agent_event *event)
 450 {
 451         int ret;
 452         uint64_t data_size;
 453         uint32_t reply_ret_code;
 454         struct lttcomm_agent_disable msg;
 455         struct lttcomm_agent_generic_reply reply;
 456
 457         assert(app);
 458         assert(app->sock);
 459         assert(event);
 460
 461         DBG2("Agent disabling event %s for app pid: %d and socket %d", event->name,
 462                         app->pid, app->sock->fd);
 463
 464         data_size = sizeof(msg);
 465
 466         ret = send_header(app->sock, data_size, AGENT_CMD_DISABLE, 0);
 467         if (ret < 0) {
 468                 goto error_io;
 469         }
 470
 471         memset(&msg, 0, sizeof(msg));
 472         strncpy(msg.name, event->name, sizeof(msg.name));
 473         ret = send_payload(app->sock, &msg, sizeof(msg));
 474         if (ret < 0) {
 475                 goto error_io;
 476         }
 477
 478         ret = recv_reply(app->sock, &reply, sizeof(reply));
 479         if (ret < 0) {
 480                 goto error_io;
 481         }
 482
 483         reply_ret_code = be32toh(reply.ret_code);
 484         log_reply_code(reply_ret_code);
 485         switch (reply_ret_code) {
 486         case AGENT_RET_CODE_SUCCESS:
 487                 break;
 488         case AGENT_RET_CODE_UNKNOWN_NAME:
 489                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 490                 goto error;
 491         default:
 492                 ret = LTTNG_ERR_UNK;
 493                 goto error;
 494         }
 495
 496         return LTTNG_OK;
 497
 498 error_io:
 499         ret = LTTNG_ERR_UST_DISABLE_FAIL;
 500 error:
 501         return ret;
 502 }
 503
 504 /*
 505  * Send back the registration DONE command to a given agent application.
 506  *
 507  * Return 0 on success or else a negative value.
 508  */
 509 int agent_send_registration_done(struct agent_app *app)
 510 {
 511         assert(app);
 512         assert(app->sock);
 513
 514         DBG("Agent sending registration done to app socket %d", app->sock->fd);
 515
 516         return send_header(app->sock, 0, AGENT_CMD_REG_DONE, 0);
 517 }
 518
 519 /*
 520  * Enable agent event on every agent applications registered with the session
 521  * daemon.
 522  *
 523  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 524  */
 525 int agent_enable_event(struct agent_event *event,
 526                 enum lttng_domain_type domain)
 527 {
 528         int ret;
 529         struct agent_app *app;
 530         struct lttng_ht_iter iter;
 531
 532         assert(event);
 533
 534         rcu_read_lock();
 535
 536         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 537                         node.node) {
 538                 if (app->domain != domain) {
 539                         continue;
 540                 }
 541
 542                 /* Enable event on agent application through TCP socket. */
 543                 ret = enable_event(app, event);
 544                 if (ret != LTTNG_OK) {
 545                         goto error;
 546                 }
 547         }
 548
 549         event->enabled = 1;
 550         ret = LTTNG_OK;
 551
 552 error:
 553         rcu_read_unlock();
 554         return ret;
 555 }
 556
 557 /*
 558  * Disable agent event on every agent applications registered with the session
 559  * daemon.
 560  *
 561  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 562  */
 563 int agent_disable_event(struct agent_event *event,
 564                 enum lttng_domain_type domain)
 565 {
 566         int ret = LTTNG_OK;
 567         struct agent_app *app;
 568         struct lttng_ht_iter iter;
 569
 570         assert(event);
 571         if (!event->enabled) {
 572                 goto end;
 573         }
 574
 575         rcu_read_lock();
 576
 577         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 578                         node.node) {
 579                 if (app->domain != domain) {
 580                         continue;
 581                 }
 582
 583                 /* Enable event on agent application through TCP socket. */
 584                 ret = disable_event(app, event);
 585                 if (ret != LTTNG_OK) {
 586                         goto error;
 587                 }
 588         }
 589
 590         event->enabled = 0;
 591
 592 error:
 593         rcu_read_unlock();
 594 end:
 595         return ret;
 596 }
 597
 598 /*
 599  * Ask every agent for the list of possible event. Events is allocated with the
 600  * events of every agent application.
 601  *
 602  * Return the number of events or else a negative value.
 603  */
 604 int agent_list_events(struct lttng_event **events,
 605                 enum lttng_domain_type domain)
 606 {
 607         int ret;
 608         size_t nbmem, count = 0;
 609         struct agent_app *app;
 610         struct lttng_event *tmp_events = NULL;
 611         struct lttng_ht_iter iter;
 612
 613         assert(events);
 614
 615         DBG2("Agent listing events for domain %d", domain);
 616
 617         nbmem = UST_APP_EVENT_LIST_SIZE;
 618         tmp_events = zmalloc(nbmem * sizeof(*tmp_events));
 619         if (!tmp_events) {
 620                 PERROR("zmalloc agent list events");
 621                 ret = -ENOMEM;
 622                 goto error;
 623         }
 624
 625         rcu_read_lock();
 626         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 627                         node.node) {
 628                 ssize_t nb_ev;
 629                 struct lttng_event *agent_events;
 630
 631                 /* Skip domain not asked by the list. */
 632                 if (app->domain != domain) {
 633                         continue;
 634                 }
 635
 636                 nb_ev = list_events(app, &agent_events);
 637                 if (nb_ev < 0) {
 638                         ret = nb_ev;
 639                         goto error_unlock;
 640                 }
 641
 642                 if (count + nb_ev > nbmem) {
 643                         /* In case the realloc fails, we free the memory */
 644                         struct lttng_event *new_tmp_events;
 645                         size_t new_nbmem;
 646
 647                         new_nbmem = max_t(size_t, count + nb_ev, nbmem << 1);
 648                         DBG2("Reallocating agent event list from %zu to %zu entries",
 649                                         nbmem, new_nbmem);
 650                         new_tmp_events = realloc(tmp_events,
 651                                 new_nbmem * sizeof(*new_tmp_events));
 652                         if (!new_tmp_events) {
 653                                 PERROR("realloc agent events");
 654                                 ret = -ENOMEM;
 655                                 free(agent_events);
 656                                 goto error_unlock;
 657                         }
 658                         /* Zero the new memory */
 659                         memset(new_tmp_events + nbmem, 0,
 660                                 (new_nbmem - nbmem) * sizeof(*new_tmp_events));
 661                         nbmem = new_nbmem;
 662                         tmp_events = new_tmp_events;
 663                 }
 664                 memcpy(tmp_events + count, agent_events,
 665                         nb_ev * sizeof(*tmp_events));
 666                 free(agent_events);
 667                 count += nb_ev;
 668         }
 669         rcu_read_unlock();
 670
 671         ret = count;
 672         *events = tmp_events;
 673         return ret;
 674
 675 error_unlock:
 676         rcu_read_unlock();
 677 error:
 678         free(tmp_events);
 679         return ret;
 680 }
 681
 682 /*
 683  * Create a agent app object using the given PID.
 684  *
 685  * Return newly allocated object or else NULL on error.
 686  */
 687 struct agent_app *agent_create_app(pid_t pid, enum lttng_domain_type domain,
 688                 struct lttcomm_sock *sock)
 689 {
 690         struct agent_app *app;
 691
 692         assert(sock);
 693
 694         app = zmalloc(sizeof(*app));
 695         if (!app) {
 696                 PERROR("zmalloc agent create");
 697                 goto error;
 698         }
 699
 700         app->pid = pid;
 701         app->domain = domain;
 702         app->sock = sock;
 703         lttng_ht_node_init_ulong(&app->node, (unsigned long) app->sock->fd);
 704
 705 error:
 706         return app;
 707 }
 708
 709 /*
 710  * Lookup agent app by socket in the global hash table.
 711  *
 712  * RCU read side lock MUST be acquired.
 713  *
 714  * Return object if found else NULL.
 715  */
 716 struct agent_app *agent_find_app_by_sock(int sock)
 717 {
 718         struct lttng_ht_node_ulong *node;
 719         struct lttng_ht_iter iter;
 720         struct agent_app *app;
 721
 722         assert(sock >= 0);
 723
 724         lttng_ht_lookup(agent_apps_ht_by_sock, (void *)((unsigned long) sock), &iter);
 725         node = lttng_ht_iter_get_node_ulong(&iter);
 726         if (node == NULL) {
 727                 goto error;
 728         }
 729         app = caa_container_of(node, struct agent_app, node);
 730
 731         DBG3("Agent app pid %d found by sock %d.", app->pid, sock);
 732         return app;
 733
 734 error:
 735         DBG3("Agent app NOT found by sock %d.", sock);
 736         return NULL;
 737 }
 738
 739 /*
 740  * Add agent application object to the global hash table.
 741  */
 742 void agent_add_app(struct agent_app *app)
 743 {
 744         assert(app);
 745
 746         DBG3("Agent adding app sock: %d and pid: %d to ht", app->sock->fd, app->pid);
 747         lttng_ht_add_unique_ulong(agent_apps_ht_by_sock, &app->node);
 748 }
 749
 750 /*
 751  * Delete agent application from the global hash table.
 752  *
 753  * rcu_read_lock() must be held by the caller.
 754  */
 755 void agent_delete_app(struct agent_app *app)
 756 {
 757         int ret;
 758         struct lttng_ht_iter iter;
 759
 760         assert(app);
 761
 762         DBG3("Agent deleting app pid: %d and sock: %d", app->pid, app->sock->fd);
 763
 764         iter.iter.node = &app->node.node;
 765         ret = lttng_ht_del(agent_apps_ht_by_sock, &iter);
 766         assert(!ret);
 767 }
 768
 769 /*
 770  * Destroy an agent application object by detaching it from its corresponding
 771  * UST app if one is connected by closing the socket. Finally, perform a
 772  * delayed memory reclaim.
 773  */
 774 void agent_destroy_app(struct agent_app *app)
 775 {
 776         assert(app);
 777
 778         if (app->sock) {
 779                 app->sock->ops->close(app->sock);
 780                 lttcomm_destroy_sock(app->sock);
 781         }
 782
 783         call_rcu(&app->node.head, destroy_app_agent_rcu);
 784 }
 785
 786 /*
 787  * Initialize an already allocated agent object.
 788  *
 789  * Return 0 on success or else a negative errno value.
 790  */
 791 int agent_init(struct agent *agt)
 792 {
 793         int ret;
 794
 795         assert(agt);
 796
 797         agt->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 798         if (!agt->events) {
 799                 ret = -ENOMEM;
 800                 goto error;
 801         }
 802         lttng_ht_node_init_u64(&agt->node, agt->domain);
 803
 804         return 0;
 805
 806 error:
 807         return ret;
 808 }
 809
 810 /*
 811  * Add agent object to the given hash table.
 812  */
 813 void agent_add(struct agent *agt, struct lttng_ht *ht)
 814 {
 815         assert(agt);
 816         assert(ht);
 817
 818         DBG3("Agent adding from domain %d", agt->domain);
 819
 820         lttng_ht_add_unique_u64(ht, &agt->node);
 821 }
 822
 823 /*
 824  * Create an agent object for the given domain.
 825  *
 826  * Return the allocated agent or NULL on error.
 827  */
 828 struct agent *agent_create(enum lttng_domain_type domain)
 829 {
 830         int ret;
 831         struct agent *agt;
 832
 833         agt = zmalloc(sizeof(struct agent));
 834         if (!agt) {
 835                 goto error;
 836         }
 837         agt->domain = domain;
 838
 839         ret = agent_init(agt);
 840         if (ret < 0) {
 841                 free(agt);
 842                 agt = NULL;
 843                 goto error;
 844         }
 845
 846 error:
 847         return agt;
 848 }
 849
 850 /*
 851  * Create a newly allocated agent event data structure.
 852  * Ownership of filter_expression is taken.
 853  *
 854  * Return a new object else NULL on error.
 855  */
 856 struct agent_event *agent_create_event(const char *name,
 857                 enum lttng_loglevel_type loglevel_type, int loglevel_value,
 858                 struct lttng_filter_bytecode *filter, char *filter_expression)
 859 {
 860         struct agent_event *event = NULL;
 861
 862         DBG3("Agent create new event with name %s, loglevel type %d and loglevel value %d",
 863                 name, loglevel_type, loglevel_value);
 864
 865         if (!name) {
 866                 ERR("Failed to create agent event; no name provided.");
 867                 goto error;
 868         }
 869
 870         event = zmalloc(sizeof(*event));
 871         if (!event) {
 872                 goto error;
 873         }
 874
 875         strncpy(event->name, name, sizeof(event->name));
 876         event->name[sizeof(event->name) - 1] = '\0';
 877         lttng_ht_node_init_str(&event->node, event->name);
 878
 879         event->loglevel_value = loglevel_value;
 880         event->loglevel_type = loglevel_type;
 881         event->filter = filter;
 882         event->filter_expression = filter_expression;
 883 error:
 884         return event;
 885 }
 886
 887 /*
 888  * Unique add of a agent event to an agent object.
 889  */
 890 void agent_add_event(struct agent_event *event, struct agent *agt)
 891 {
 892         assert(event);
 893         assert(agt);
 894         assert(agt->events);
 895
 896         DBG3("Agent adding event %s", event->name);
 897         add_unique_agent_event(agt->events, event);
 898         agt->being_used = 1;
 899 }
 900
 901 /*
 902  * Find multiple agent events sharing the given name.
 903  *
 904  * RCU read side lock MUST be acquired. It must be held for the
 905  * duration of the iteration.
 906  *
 907  * Sets the given iterator.
 908  */
 909 void agent_find_events_by_name(const char *name, struct agent *agt,
 910                 struct lttng_ht_iter* iter)
 911 {
 912         struct lttng_ht *ht;
 913         struct agent_ht_key key;
 914
 915         assert(name);
 916         assert(agt);
 917         assert(agt->events);
 918         assert(iter);
 919
 920         ht = agt->events;
 921         key.name = name;
 922
 923         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 924                         ht_match_event_by_name, &key, &iter->iter);
 925 }
 926
 927 /*
 928  * Get the next agent event duplicate by name. This should be called
 929  * after a call to agent_find_events_by_name() to iterate on events.
 930  *
 931  * The RCU read lock must be held during the iteration and for as long
 932  * as the object the iterator points to remains in use.
 933  */
 934 void agent_event_next_duplicate(const char *name,
 935                 struct agent *agt, struct lttng_ht_iter* iter)
 936 {
 937         struct agent_ht_key key;
 938
 939         key.name = name;
 940
 941         cds_lfht_next_duplicate(agt->events->ht, ht_match_event_by_name,
 942                 &key, &iter->iter);
 943 }
 944
 945 /*
 946  * Find a agent event in the given agent using name and loglevel.
 947  *
 948  * RCU read side lock MUST be acquired. It must be kept for as long as
 949  * the returned agent_event is used.
 950  *
 951  * Return object if found else NULL.
 952  */
 953 struct agent_event *agent_find_event(const char *name,
 954                 enum lttng_loglevel_type loglevel_type, int loglevel_value,
 955                 struct agent *agt)
 956 {
 957         struct lttng_ht_node_str *node;
 958         struct lttng_ht_iter iter;
 959         struct lttng_ht *ht;
 960         struct agent_ht_key key;
 961
 962         assert(name);
 963         assert(agt);
 964         assert(agt->events);
 965
 966         ht = agt->events;
 967         key.name = name;
 968         key.loglevel_value = loglevel_value;
 969         key.loglevel_type = loglevel_type;
 970
 971         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 972                         ht_match_event, &key, &iter.iter);
 973         node = lttng_ht_iter_get_node_str(&iter);
 974         if (node == NULL) {
 975                 goto error;
 976         }
 977
 978         DBG3("Agent event found %s.", name);
 979         return caa_container_of(node, struct agent_event, node);
 980
 981 error:
 982         DBG3("Agent event NOT found %s.", name);
 983         return NULL;
 984 }
 985
 986 /*
 987  * Free given agent event. This event must not be globally visible at this
 988  * point (only expected to be used on failure just after event creation). After
 989  * this call, the pointer is not usable anymore.
 990  */
 991 void agent_destroy_event(struct agent_event *event)
 992 {
 993         assert(event);
 994
 995         free(event->filter);
 996         free(event->filter_expression);
 997         free(event->exclusion);
 998         free(event);
 999 }
1000
1001 /*
1002  * Destroy an agent completely.
1003  */
1004 void agent_destroy(struct agent *agt)
1005 {
1006         struct lttng_ht_node_str *node;
1007         struct lttng_ht_iter iter;
1008
1009         assert(agt);
1010
1011         DBG3("Agent destroy");
1012
1013         rcu_read_lock();
1014         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, node, node) {
1015                 int ret;
1016                 struct agent_event *event;
1017
1018                 /*
1019                  * When destroying an event, we have to try to disable it on the agent
1020                  * side so the event stops generating data. The return value is not
1021                  * important since we have to continue anyway destroying the object.
1022                  */
1023                 event = caa_container_of(node, struct agent_event, node);
1024                 (void) agent_disable_event(event, agt->domain);
1025
1026                 ret = lttng_ht_del(agt->events, &iter);
1027                 assert(!ret);
1028                 call_rcu(&node->head, destroy_event_agent_rcu);
1029         }
1030         rcu_read_unlock();
1031
1032         ht_cleanup_push(agt->events);
1033         free(agt);
1034 }
1035
1036 /*
1037  * Allocate agent_apps_ht_by_sock.
1038  */
1039 int agent_app_ht_alloc(void)
1040 {
1041         int ret = 0;
1042
1043         agent_apps_ht_by_sock = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
1044         if (!agent_apps_ht_by_sock) {
1045                 ret = -1;
1046         }
1047
1048         return ret;
1049 }
1050
1051 /*
1052  * Destroy a agent application by socket.
1053  */
1054 void agent_destroy_app_by_sock(int sock)
1055 {
1056         struct agent_app *app;
1057
1058         assert(sock >= 0);
1059
1060         /*
1061          * Not finding an application is a very important error that should NEVER
1062          * happen. The hash table deletion is ONLY done through this call when the
1063          * main sessiond thread is torn down.
1064          */
1065         rcu_read_lock();
1066         app = agent_find_app_by_sock(sock);
1067         assert(app);
1068
1069         /* RCU read side lock is assumed to be held by this function. */
1070         agent_delete_app(app);
1071
1072         /* The application is freed in a RCU call but the socket is closed here. */
1073         agent_destroy_app(app);
1074         rcu_read_unlock();
1075 }
1076
1077 /*
1078  * Clean-up the agent app hash table and destroy it.
1079  */
1080 void agent_app_ht_clean(void)
1081 {
1082         struct lttng_ht_node_ulong *node;
1083         struct lttng_ht_iter iter;
1084
1085         if (!agent_apps_ht_by_sock) {
1086                 return;
1087         }
1088         rcu_read_lock();
1089         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, node, node) {
1090                 struct agent_app *app;
1091
1092                 app = caa_container_of(node, struct agent_app, node);
1093                 agent_destroy_app_by_sock(app->sock->fd);
1094         }
1095         rcu_read_unlock();
1096
1097         lttng_ht_destroy(agent_apps_ht_by_sock);
1098 }
1099
1100 /*
1101  * Update a agent application (given socket) using the given agent.
1102  *
1103  * Note that this function is most likely to be used with a tracing session
1104  * thus the caller should make sure to hold the appropriate lock(s).
1105  */
1106 void agent_update(struct agent *agt, int sock)
1107 {
1108         int ret;
1109         struct agent_app *app;
1110         struct agent_event *event;
1111         struct lttng_ht_iter iter;
1112
1113         assert(agt);
1114         assert(sock >= 0);
1115
1116         DBG("Agent updating app socket %d", sock);
1117
1118         rcu_read_lock();
1119         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, event, node.node) {
1120                 /* Skip event if disabled. */
1121                 if (!event->enabled) {
1122                         continue;
1123                 }
1124
1125                 app = agent_find_app_by_sock(sock);
1126                 /*
1127                  * We are in the registration path thus if the application is gone,
1128                  * there is a serious code flow error.
1129                  */
1130                 assert(app);
1131
1132                 ret = enable_event(app, event);
1133                 if (ret != LTTNG_OK) {
1134                         DBG2("Agent update unable to enable event %s on app pid: %d sock %d",
1135                                         event->name, app->pid, app->sock->fd);
1136                         /* Let's try the others here and don't assume the app is dead. */
1137                         continue;
1138                 }
1139         }
1140         rcu_read_unlock();
1141 }