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