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         struct lttng_event *tmp_events = NULL;
 277         struct lttcomm_agent_list_reply *reply = NULL;
 278         struct lttcomm_agent_list_reply_hdr reply_hdr;
 279
 280         assert(app);
 281         assert(app->sock);
 282         assert(events);
 283
 284         DBG2("Agent listing events for app pid: %d and socket %d", app->pid,
 285                         app->sock->fd);
 286
 287         ret = send_header(app->sock, 0, AGENT_CMD_LIST, 0);
 288         if (ret < 0) {
 289                 goto error_io;
 290         }
 291
 292         /* Get list header so we know how much we'll receive. */
 293         ret = recv_reply(app->sock, &reply_hdr, sizeof(reply_hdr));
 294         if (ret < 0) {
 295                 goto error_io;
 296         }
 297
 298         switch (be32toh(reply_hdr.ret_code)) {
 299         case AGENT_RET_CODE_SUCCESS:
 300                 data_size = be32toh(reply_hdr.data_size) + sizeof(*reply);
 301                 break;
 302         default:
 303                 ERR("Agent returned an unknown code: %" PRIu32,
 304                                 be32toh(reply_hdr.ret_code));
 305                 ret = LTTNG_ERR_FATAL;
 306                 goto error;
 307         }
 308
 309         reply = zmalloc(data_size);
 310         if (!reply) {
 311                 ret = LTTNG_ERR_NOMEM;
 312                 goto error;
 313         }
 314
 315         /* Get the list with the appropriate data size. */
 316         ret = recv_reply(app->sock, reply, data_size);
 317         if (ret < 0) {
 318                 goto error_io;
 319         }
 320
 321         nb_event = be32toh(reply->nb_event);
 322         tmp_events = zmalloc(sizeof(*tmp_events) * nb_event);
 323         if (!tmp_events) {
 324                 ret = LTTNG_ERR_NOMEM;
 325                 goto error;
 326         }
 327
 328         for (i = 0; i < nb_event; i++) {
 329                 offset += len;
 330                 strncpy(tmp_events[i].name, reply->payload + offset,
 331                                 sizeof(tmp_events[i].name));
 332                 tmp_events[i].pid = app->pid;
 333                 tmp_events[i].enabled = -1;
 334                 len = strlen(reply->payload + offset) + 1;
 335         }
 336
 337         *events = tmp_events;
 338
 339         free(reply);
 340         return nb_event;
 341
 342 error_io:
 343         ret = LTTNG_ERR_UST_LIST_FAIL;
 344 error:
 345         free(reply);
 346         free(tmp_events);
 347         return -ret;
 348
 349 }
 350
 351 /*
 352  * Internal enable agent event on a agent application. This function
 353  * communicates with the agent to enable a given event.
 354  *
 355  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 356  */
 357 static int enable_event(struct agent_app *app, struct agent_event *event)
 358 {
 359         int ret;
 360         uint64_t data_size;
 361         struct lttcomm_agent_enable msg;
 362         struct lttcomm_agent_generic_reply reply;
 363
 364         assert(app);
 365         assert(app->sock);
 366         assert(event);
 367
 368         DBG2("Agent enabling event %s for app pid: %d and socket %d", event->name,
 369                         app->pid, app->sock->fd);
 370
 371         data_size = sizeof(msg);
 372
 373         ret = send_header(app->sock, data_size, AGENT_CMD_ENABLE, 0);
 374         if (ret < 0) {
 375                 goto error_io;
 376         }
 377
 378         memset(&msg, 0, sizeof(msg));
 379         msg.loglevel = event->loglevel;
 380         msg.loglevel_type = event->loglevel_type;
 381         strncpy(msg.name, event->name, sizeof(msg.name));
 382         ret = send_payload(app->sock, &msg, sizeof(msg));
 383         if (ret < 0) {
 384                 goto error_io;
 385         }
 386
 387         ret = recv_reply(app->sock, &reply, sizeof(reply));
 388         if (ret < 0) {
 389                 goto error_io;
 390         }
 391
 392         switch (be32toh(reply.ret_code)) {
 393         case AGENT_RET_CODE_SUCCESS:
 394                 break;
 395         case AGENT_RET_CODE_UNKNOWN_NAME:
 396                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 397                 goto error;
 398         default:
 399                 ERR("Agent returned an unknown code: %" PRIu32,
 400                                 be32toh(reply.ret_code));
 401                 ret = LTTNG_ERR_FATAL;
 402                 goto error;
 403         }
 404
 405         return LTTNG_OK;
 406
 407 error_io:
 408         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 409 error:
 410         return ret;
 411 }
 412
 413 /*
 414  * Internal disable agent event call on a agent application. This function
 415  * communicates with the agent to disable a given event.
 416  *
 417  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 418  */
 419 static int disable_event(struct agent_app *app, struct agent_event *event)
 420 {
 421         int ret;
 422         uint64_t data_size;
 423         struct lttcomm_agent_disable msg;
 424         struct lttcomm_agent_generic_reply reply;
 425
 426         assert(app);
 427         assert(app->sock);
 428         assert(event);
 429
 430         DBG2("Agent disabling event %s for app pid: %d and socket %d", event->name,
 431                         app->pid, app->sock->fd);
 432
 433         data_size = sizeof(msg);
 434
 435         ret = send_header(app->sock, data_size, AGENT_CMD_DISABLE, 0);
 436         if (ret < 0) {
 437                 goto error_io;
 438         }
 439
 440         memset(&msg, 0, sizeof(msg));
 441         strncpy(msg.name, event->name, sizeof(msg.name));
 442         ret = send_payload(app->sock, &msg, sizeof(msg));
 443         if (ret < 0) {
 444                 goto error_io;
 445         }
 446
 447         ret = recv_reply(app->sock, &reply, sizeof(reply));
 448         if (ret < 0) {
 449                 goto error_io;
 450         }
 451
 452         switch (be32toh(reply.ret_code)) {
 453         case AGENT_RET_CODE_SUCCESS:
 454                 break;
 455         case AGENT_RET_CODE_UNKNOWN_NAME:
 456                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 457                 goto error;
 458         default:
 459                 ERR("Agent returned an unknown code: %" PRIu32,
 460                                 be32toh(reply.ret_code));
 461                 ret = LTTNG_ERR_FATAL;
 462                 goto error;
 463         }
 464
 465         return LTTNG_OK;
 466
 467 error_io:
 468         ret = LTTNG_ERR_UST_DISABLE_FAIL;
 469 error:
 470         return ret;
 471 }
 472
 473 /*
 474  * Send back the registration DONE command to a given agent application.
 475  *
 476  * Return 0 on success or else a negative value.
 477  */
 478 int agent_send_registration_done(struct agent_app *app)
 479 {
 480         assert(app);
 481         assert(app->sock);
 482
 483         DBG("Agent sending registration done to app socket %d", app->sock->fd);
 484
 485         return send_header(app->sock, 0, AGENT_CMD_REG_DONE, 0);
 486 }
 487
 488 /*
 489  * Enable agent event on every agent applications registered with the session
 490  * daemon.
 491  *
 492  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 493  */
 494 int agent_enable_event(struct agent_event *event,
 495                 enum lttng_domain_type domain)
 496 {
 497         int ret;
 498         struct agent_app *app;
 499         struct lttng_ht_iter iter;
 500
 501         assert(event);
 502
 503         rcu_read_lock();
 504
 505         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 506                         node.node) {
 507                 if (app->domain != domain) {
 508                         continue;
 509                 }
 510
 511                 /* Enable event on agent application through TCP socket. */
 512                 ret = enable_event(app, event);
 513                 if (ret != LTTNG_OK) {
 514                         goto error;
 515                 }
 516         }
 517
 518         event->enabled = 1;
 519         ret = LTTNG_OK;
 520
 521 error:
 522         rcu_read_unlock();
 523         return ret;
 524 }
 525
 526 /*
 527  * Disable agent event on every agent applications registered with the session
 528  * daemon.
 529  *
 530  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 531  */
 532 int agent_disable_event(struct agent_event *event,
 533                 enum lttng_domain_type domain)
 534 {
 535         int ret = LTTNG_OK;
 536         struct agent_app *app;
 537         struct lttng_ht_iter iter;
 538
 539         assert(event);
 540         if (!event->enabled) {
 541                 goto end;
 542         }
 543
 544         rcu_read_lock();
 545
 546         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 547                         node.node) {
 548                 if (app->domain != domain) {
 549                         continue;
 550                 }
 551
 552                 /* Enable event on agent application through TCP socket. */
 553                 ret = disable_event(app, event);
 554                 if (ret != LTTNG_OK) {
 555                         goto error;
 556                 }
 557         }
 558
 559         event->enabled = 0;
 560
 561 error:
 562         rcu_read_unlock();
 563 end:
 564         return ret;
 565 }
 566
 567 /*
 568  * Ask every agent for the list of possible event. Events is allocated with the
 569  * events of every agent application.
 570  *
 571  * Return the number of events or else a negative value.
 572  */
 573 int agent_list_events(struct lttng_event **events,
 574                 enum lttng_domain_type domain)
 575 {
 576         int ret;
 577         size_t nbmem, count = 0;
 578         struct agent_app *app;
 579         struct lttng_event *tmp_events = NULL;
 580         struct lttng_ht_iter iter;
 581
 582         assert(events);
 583
 584         DBG2("Agent listing events for domain %d", domain);
 585
 586         nbmem = UST_APP_EVENT_LIST_SIZE;
 587         tmp_events = zmalloc(nbmem * sizeof(*tmp_events));
 588         if (!tmp_events) {
 589                 PERROR("zmalloc agent list events");
 590                 ret = -ENOMEM;
 591                 goto error;
 592         }
 593
 594         rcu_read_lock();
 595         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 596                         node.node) {
 597                 ssize_t nb_ev;
 598                 struct lttng_event *agent_events;
 599
 600                 /* Skip domain not asked by the list. */
 601                 if (app->domain != domain) {
 602                         continue;
 603                 }
 604
 605                 nb_ev = list_events(app, &agent_events);
 606                 if (nb_ev < 0) {
 607                         ret = nb_ev;
 608                         goto error_unlock;
 609                 }
 610
 611                 if (count + nb_ev > nbmem) {
 612                         /* In case the realloc fails, we free the memory */
 613                         struct lttng_event *new_tmp_events;
 614                         size_t new_nbmem;
 615
 616                         new_nbmem = max_t(size_t, count + nb_ev, nbmem << 1);
 617                         DBG2("Reallocating agent event list from %zu to %zu entries",
 618                                         nbmem, new_nbmem);
 619                         new_tmp_events = realloc(tmp_events,
 620                                 new_nbmem * sizeof(*new_tmp_events));
 621                         if (!new_tmp_events) {
 622                                 PERROR("realloc agent events");
 623                                 ret = -ENOMEM;
 624                                 free(agent_events);
 625                                 goto error_unlock;
 626                         }
 627                         /* Zero the new memory */
 628                         memset(new_tmp_events + nbmem, 0,
 629                                 (new_nbmem - nbmem) * sizeof(*new_tmp_events));
 630                         nbmem = new_nbmem;
 631                         tmp_events = new_tmp_events;
 632                 }
 633                 memcpy(tmp_events + count, agent_events,
 634                         nb_ev * sizeof(*tmp_events));
 635                 free(agent_events);
 636                 count += nb_ev;
 637         }
 638         rcu_read_unlock();
 639
 640         ret = count;
 641         *events = tmp_events;
 642         return ret;
 643
 644 error_unlock:
 645         rcu_read_unlock();
 646 error:
 647         free(tmp_events);
 648         return ret;
 649 }
 650
 651 /*
 652  * Create a agent app object using the given PID.
 653  *
 654  * Return newly allocated object or else NULL on error.
 655  */
 656 struct agent_app *agent_create_app(pid_t pid, enum lttng_domain_type domain,
 657                 struct lttcomm_sock *sock)
 658 {
 659         struct agent_app *app;
 660
 661         assert(sock);
 662
 663         app = zmalloc(sizeof(*app));
 664         if (!app) {
 665                 PERROR("zmalloc agent create");
 666                 goto error;
 667         }
 668
 669         app->pid = pid;
 670         app->domain = domain;
 671         app->sock = sock;
 672         lttng_ht_node_init_ulong(&app->node, (unsigned long) app->sock->fd);
 673
 674 error:
 675         return app;
 676 }
 677
 678 /*
 679  * Lookup agent app by socket in the global hash table.
 680  *
 681  * RCU read side lock MUST be acquired.
 682  *
 683  * Return object if found else NULL.
 684  */
 685 struct agent_app *agent_find_app_by_sock(int sock)
 686 {
 687         struct lttng_ht_node_ulong *node;
 688         struct lttng_ht_iter iter;
 689         struct agent_app *app;
 690
 691         assert(sock >= 0);
 692
 693         lttng_ht_lookup(agent_apps_ht_by_sock, (void *)((unsigned long) sock), &iter);
 694         node = lttng_ht_iter_get_node_ulong(&iter);
 695         if (node == NULL) {
 696                 goto error;
 697         }
 698         app = caa_container_of(node, struct agent_app, node);
 699
 700         DBG3("Agent app pid %d found by sock %d.", app->pid, sock);
 701         return app;
 702
 703 error:
 704         DBG3("Agent app NOT found by sock %d.", sock);
 705         return NULL;
 706 }
 707
 708 /*
 709  * Add agent application object to the global hash table.
 710  */
 711 void agent_add_app(struct agent_app *app)
 712 {
 713         assert(app);
 714
 715         DBG3("Agent adding app sock: %d and pid: %d to ht", app->sock->fd, app->pid);
 716
 717         rcu_read_lock();
 718         lttng_ht_add_unique_ulong(agent_apps_ht_by_sock, &app->node);
 719         rcu_read_unlock();
 720 }
 721
 722 /*
 723  * Delete agent application from the global hash table.
 724  *
 725  * rcu_read_lock() must be held by the caller.
 726  */
 727 void agent_delete_app(struct agent_app *app)
 728 {
 729         int ret;
 730         struct lttng_ht_iter iter;
 731
 732         assert(app);
 733
 734         DBG3("Agent deleting app pid: %d and sock: %d", app->pid, app->sock->fd);
 735
 736         iter.iter.node = &app->node.node;
 737         ret = lttng_ht_del(agent_apps_ht_by_sock, &iter);
 738         assert(!ret);
 739 }
 740
 741 /*
 742  * Destroy an agent application object by detaching it from its corresponding
 743  * UST app if one is connected by closing the socket. Finally, perform a
 744  * delayed memory reclaim.
 745  */
 746 void agent_destroy_app(struct agent_app *app)
 747 {
 748         assert(app);
 749
 750         if (app->sock) {
 751                 app->sock->ops->close(app->sock);
 752                 lttcomm_destroy_sock(app->sock);
 753         }
 754
 755         call_rcu(&app->node.head, destroy_app_agent_rcu);
 756 }
 757
 758 /*
 759  * Initialize an already allocated agent object.
 760  *
 761  * Return 0 on success or else a negative errno value.
 762  */
 763 int agent_init(struct agent *agt)
 764 {
 765         int ret;
 766
 767         assert(agt);
 768
 769         agt->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 770         if (!agt->events) {
 771                 ret = -ENOMEM;
 772                 goto error;
 773         }
 774         lttng_ht_node_init_u64(&agt->node, agt->domain);
 775
 776         return 0;
 777
 778 error:
 779         return ret;
 780 }
 781
 782 /*
 783  * Add agent object to the given hash table.
 784  */
 785 void agent_add(struct agent *agt, struct lttng_ht *ht)
 786 {
 787         assert(agt);
 788         assert(ht);
 789
 790         DBG3("Agent adding from domain %d", agt->domain);
 791
 792         rcu_read_lock();
 793         lttng_ht_add_unique_u64(ht, &agt->node);
 794         rcu_read_unlock();
 795 }
 796
 797 /*
 798  * Create an agent object for the given domain.
 799  *
 800  * Return the allocated agent or NULL on error.
 801  */
 802 struct agent *agent_create(enum lttng_domain_type domain)
 803 {
 804         int ret;
 805         struct agent *agt;
 806
 807         agt = zmalloc(sizeof(*agt));
 808         if (!agt) {
 809                 goto error;
 810         }
 811         agt->domain = domain;
 812
 813         ret = agent_init(agt);
 814         if (ret < 0) {
 815                 free(agt);
 816                 agt = NULL;
 817                 goto error;
 818         }
 819
 820 error:
 821         return agt;
 822 }
 823
 824 /*
 825  * Create a newly allocated agent event data structure. If name is valid, it's
 826  * copied into the created event.
 827  *
 828  * Return a new object else NULL on error.
 829  */
 830 struct agent_event *agent_create_event(const char *name,
 831                 struct lttng_filter_bytecode *filter)
 832 {
 833         struct agent_event *event;
 834
 835         DBG3("Agent create new event with name %s", name);
 836
 837         event = zmalloc(sizeof(*event));
 838         if (!event) {
 839                 goto error;
 840         }
 841
 842         if (name) {
 843                 strncpy(event->name, name, sizeof(event->name));
 844                 event->name[sizeof(event->name) - 1] = '\0';
 845                 lttng_ht_node_init_str(&event->node, event->name);
 846         }
 847
 848         if (filter) {
 849                 event->filter = filter;
 850         }
 851
 852 error:
 853         return event;
 854 }
 855
 856 /*
 857  * Unique add of a agent event to an agent object.
 858  */
 859 void agent_add_event(struct agent_event *event, struct agent *agt)
 860 {
 861         assert(event);
 862         assert(agt);
 863         assert(agt->events);
 864
 865         DBG3("Agent adding event %s", event->name);
 866
 867         rcu_read_lock();
 868         add_unique_agent_event(agt->events, event);
 869         rcu_read_unlock();
 870         agt->being_used = 1;
 871 }
 872
 873 /*
 874  * Find a agent event in the given agent using name.
 875  *
 876  * RCU read side lock MUST be acquired.
 877  *
 878  * Return object if found else NULL.
 879  */
 880 struct agent_event *agent_find_event_by_name(const char *name,
 881                 struct agent *agt)
 882 {
 883         struct lttng_ht_node_str *node;
 884         struct lttng_ht_iter iter;
 885         struct lttng_ht *ht;
 886         struct agent_ht_key key;
 887
 888         assert(name);
 889         assert(agt);
 890         assert(agt->events);
 891
 892         ht = agt->events;
 893         key.name = name;
 894
 895         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 896                         ht_match_event_by_name, &key, &iter.iter);
 897         node = lttng_ht_iter_get_node_str(&iter);
 898         if (node == NULL) {
 899                 goto error;
 900         }
 901
 902         DBG3("Agent event found %s by name.", name);
 903         return caa_container_of(node, struct agent_event, node);
 904
 905 error:
 906         DBG3("Agent NOT found by name %s.", name);
 907         return NULL;
 908 }
 909
 910 /*
 911  * Find a agent event in the given agent using name and loglevel.
 912  *
 913  * RCU read side lock MUST be acquired.
 914  *
 915  * Return object if found else NULL.
 916  */
 917 struct agent_event *agent_find_event(const char *name, int loglevel,
 918                 struct agent *agt)
 919 {
 920         struct lttng_ht_node_str *node;
 921         struct lttng_ht_iter iter;
 922         struct lttng_ht *ht;
 923         struct agent_ht_key key;
 924
 925         assert(name);
 926         assert(agt);
 927         assert(agt->events);
 928
 929         ht = agt->events;
 930         key.name = name;
 931         key.loglevel = loglevel;
 932
 933         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 934                         ht_match_event, &key, &iter.iter);
 935         node = lttng_ht_iter_get_node_str(&iter);
 936         if (node == NULL) {
 937                 goto error;
 938         }
 939
 940         DBG3("Agent event found %s.", name);
 941         return caa_container_of(node, struct agent_event, node);
 942
 943 error:
 944         DBG3("Agent event NOT found %s.", name);
 945         return NULL;
 946 }
 947
 948 /*
 949  * Free given agent event. This event must not be globally visible at this
 950  * point (only expected to be used on failure just after event creation). After
 951  * this call, the pointer is not usable anymore.
 952  */
 953 void agent_destroy_event(struct agent_event *event)
 954 {
 955         assert(event);
 956
 957         free(event->filter);
 958         free(event);
 959 }
 960
 961 /*
 962  * Destroy an agent completely. Note that the given pointer is NOT freed
 963  * thus a reference to static or stack data can be passed to this function.
 964  */
 965 void agent_destroy(struct agent *agt)
 966 {
 967         struct lttng_ht_node_str *node;
 968         struct lttng_ht_iter iter;
 969
 970         assert(agt);
 971
 972         DBG3("Agent destroy");
 973
 974         /*
 975          * Just ignore if no events hash table exists. This is possible if for
 976          * instance an agent object was allocated but not initialized.
 977          */
 978         if (!agt->events) {
 979                 return;
 980         }
 981
 982         rcu_read_lock();
 983         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, node, node) {
 984                 int ret;
 985                 struct agent_event *event;
 986
 987                 /*
 988                  * When destroying an event, we have to try to disable it on the agent
 989                  * side so the event stops generating data. The return value is not
 990                  * important since we have to continue anyway destroying the object.
 991                  */
 992                 event = caa_container_of(node, struct agent_event, node);
 993                 (void) agent_disable_event(event, agt->domain);
 994
 995                 ret = lttng_ht_del(agt->events, &iter);
 996                 assert(!ret);
 997                 call_rcu(&node->head, destroy_event_agent_rcu);
 998         }
 999         rcu_read_unlock();
1000
1001         ht_cleanup_push(agt->events);
1002 }
1003
1004 /*
1005  * Allocate agent_apps_ht_by_sock.
1006  */
1007 int agent_app_ht_alloc(void)
1008 {
1009         int ret = 0;
1010
1011         agent_apps_ht_by_sock = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
1012         if (!agent_apps_ht_by_sock) {
1013                 ret = -1;
1014         }
1015
1016         return ret;
1017 }
1018
1019 /*
1020  * Destroy a agent application by socket.
1021  */
1022 void agent_destroy_app_by_sock(int sock)
1023 {
1024         struct agent_app *app;
1025
1026         assert(sock >= 0);
1027
1028         /*
1029          * Not finding an application is a very important error that should NEVER
1030          * happen. The hash table deletion is ONLY done through this call when the
1031          * main sessiond thread is torn down.
1032          */
1033         rcu_read_lock();
1034         app = agent_find_app_by_sock(sock);
1035         assert(app);
1036
1037         /* RCU read side lock is assumed to be held by this function. */
1038         agent_delete_app(app);
1039
1040         /* The application is freed in a RCU call but the socket is closed here. */
1041         agent_destroy_app(app);
1042         rcu_read_unlock();
1043 }
1044
1045 /*
1046  * Clean-up the agent app hash table and destroy it.
1047  */
1048 void agent_app_ht_clean(void)
1049 {
1050         struct lttng_ht_node_ulong *node;
1051         struct lttng_ht_iter iter;
1052
1053         if (!agent_apps_ht_by_sock) {
1054                 return;
1055         }
1056         rcu_read_lock();
1057         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, node, node) {
1058                 struct agent_app *app;
1059
1060                 app = caa_container_of(node, struct agent_app, node);
1061                 agent_destroy_app_by_sock(app->sock->fd);
1062         }
1063         rcu_read_unlock();
1064
1065         lttng_ht_destroy(agent_apps_ht_by_sock);
1066 }
1067
1068 /*
1069  * Update a agent application (given socket) using the given agent.
1070  *
1071  * Note that this function is most likely to be used with a tracing session
1072  * thus the caller should make sure to hold the appropriate lock(s).
1073  */
1074 void agent_update(struct agent *agt, int sock)
1075 {
1076         int ret;
1077         struct agent_app *app;
1078         struct agent_event *event;
1079         struct lttng_ht_iter iter;
1080
1081         assert(agt);
1082         assert(sock >= 0);
1083
1084         DBG("Agent updating app socket %d", sock);
1085
1086         rcu_read_lock();
1087         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, event, node.node) {
1088                 /* Skip event if disabled. */
1089                 if (!event->enabled) {
1090                         continue;
1091                 }
1092
1093                 app = agent_find_app_by_sock(sock);
1094                 /*
1095                  * We are in the registration path thus if the application is gone,
1096                  * there is a serious code flow error.
1097                  */
1098                 assert(app);
1099
1100                 ret = enable_event(app, event);
1101                 if (ret != LTTNG_OK) {
1102                         DBG2("Agent update unable to enable event %s on app pid: %d sock %d",
1103                                         event->name, app->pid, app->sock->fd);
1104                         /* Let's try the others here and don't assume the app is dead. */
1105                         continue;
1106                 }
1107         }
1108         rcu_read_unlock();
1109 }