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