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
  32 /*
  33  * Match function for the events hash table lookup by name.
  34  */
  35 static int ht_match_event_by_name(struct cds_lfht_node *node,
  36                 const void *_key)
  37 {
  38         struct agent_event *event;
  39         const struct agent_ht_key *key;
  40
  41         assert(node);
  42         assert(_key);
  43
  44         event = caa_container_of(node, struct agent_event, node.node);
  45         key = _key;
  46
  47         /* Match 1 elements of the key: name. */
  48
  49         /* Event name */
  50         if (strncmp(event->name, key->name, sizeof(event->name)) != 0) {
  51                 goto no_match;
  52         }
  53         /* Match. */
  54         return 1;
  55
  56 no_match:
  57         return 0;
  58 }
  59
  60 /*
  61  * Match function for the events hash table lookup by name and loglevel.
  62  */
  63 static int ht_match_event(struct cds_lfht_node *node,
  64                 const void *_key)
  65 {
  66         struct agent_event *event;
  67         const struct agent_ht_key *key;
  68         int ll_match;
  69
  70         assert(node);
  71         assert(_key);
  72
  73         event = caa_container_of(node, struct agent_event, node.node);
  74         key = _key;
  75
  76         /* Match 2 elements of the key: name and loglevel. */
  77
  78         /* Event name */
  79         if (strncmp(event->name, key->name, sizeof(event->name)) != 0) {
  80                 goto no_match;
  81         }
  82
  83         /* Event loglevel value and type. */
  84         ll_match = loglevels_match(event->loglevel_type,
  85                 event->loglevel_value, key->loglevel_type,
  86                 key->loglevel_value, LTTNG_EVENT_LOGLEVEL_ALL);
  87
  88         if (!ll_match) {
  89                 goto no_match;
  90         }
  91
  92         /* Filter expression */
  93         if (strncmp(event->filter_expression, key->filter_expression,
  94                         strlen(event->filter_expression)) != 0) {
  95                 goto no_match;
  96         }
  97
  98         return 1;
  99
 100 no_match:
 101         return 0;
 102 }
 103
 104 /*
 105  * Add unique agent event based on the event name and loglevel.
 106  */
 107 static void add_unique_agent_event(struct lttng_ht *ht,
 108                 struct agent_event *event)
 109 {
 110         struct cds_lfht_node *node_ptr;
 111         struct agent_ht_key key;
 112
 113         assert(ht);
 114         assert(ht->ht);
 115         assert(event);
 116
 117         key.name = event->name;
 118         key.loglevel_value = event->loglevel_value;
 119         key.loglevel_type = event->loglevel_type;
 120         key.filter_expression = event->filter_expression;
 121
 122         node_ptr = cds_lfht_add_unique(ht->ht,
 123                         ht->hash_fct(event->node.key, lttng_ht_seed),
 124                         ht_match_event, &key, &event->node.node);
 125         assert(node_ptr == &event->node.node);
 126 }
 127
 128 /*
 129  * URCU delayed agent event reclaim.
 130  */
 131 static void destroy_event_agent_rcu(struct rcu_head *head)
 132 {
 133         struct lttng_ht_node_str *node =
 134                 caa_container_of(head, struct lttng_ht_node_str, head);
 135         struct agent_event *event =
 136                 caa_container_of(node, struct agent_event, node);
 137
 138         agent_destroy_event(event);
 139 }
 140
 141 /*
 142  * URCU delayed agent app reclaim.
 143  */
 144 static void destroy_app_agent_rcu(struct rcu_head *head)
 145 {
 146         struct lttng_ht_node_ulong *node =
 147                 caa_container_of(head, struct lttng_ht_node_ulong, head);
 148         struct agent_app *app =
 149                 caa_container_of(node, struct agent_app, node);
 150
 151         free(app);
 152 }
 153
 154 /*
 155  * Communication with the agent. Send the message header to the given socket in
 156  * big endian.
 157  *
 158  * Return 0 on success or else a negative errno message of sendmsg() op.
 159  */
 160 static int send_header(struct lttcomm_sock *sock, uint64_t data_size,
 161                 uint32_t cmd, uint32_t cmd_version)
 162 {
 163         int ret;
 164         ssize_t size;
 165         struct lttcomm_agent_hdr msg;
 166
 167         assert(sock);
 168
 169         memset(&msg, 0, sizeof(msg));
 170         msg.data_size = htobe64(data_size);
 171         msg.cmd = htobe32(cmd);
 172         msg.cmd_version = htobe32(cmd_version);
 173
 174         size = sock->ops->sendmsg(sock, &msg, sizeof(msg), 0);
 175         if (size < sizeof(msg)) {
 176                 ret = -errno;
 177                 goto error;
 178         }
 179         ret = 0;
 180
 181 error:
 182         return ret;
 183 }
 184
 185 /*
 186  * Communication call with the agent. Send the payload to the given socket. The
 187  * header MUST be sent prior to this call.
 188  *
 189  * Return 0 on success or else a negative errno value of sendmsg() op.
 190  */
 191 static int send_payload(struct lttcomm_sock *sock, void *data,
 192                 size_t size)
 193 {
 194         int ret;
 195         ssize_t len;
 196
 197         assert(sock);
 198         assert(data);
 199
 200         len = sock->ops->sendmsg(sock, data, size, 0);
 201         if (len < size) {
 202                 ret = -errno;
 203                 goto error;
 204         }
 205         ret = 0;
 206
 207 error:
 208         return ret;
 209 }
 210
 211 /*
 212  * Communication call with the agent. Receive reply from the agent using the
 213  * given socket.
 214  *
 215  * Return 0 on success or else a negative errno value from recvmsg() op.
 216  */
 217 static int recv_reply(struct lttcomm_sock *sock, void *buf, size_t size)
 218 {
 219         int ret;
 220         ssize_t len;
 221
 222         assert(sock);
 223         assert(buf);
 224
 225         len = sock->ops->recvmsg(sock, buf, size, 0);
 226         if (len < size) {
 227                 ret = -errno;
 228                 goto error;
 229         }
 230         ret = 0;
 231
 232 error:
 233         return ret;
 234 }
 235
 236 /*
 237  * Internal event listing for a given app. Populate events.
 238  *
 239  * Return number of element in the list or else a negative LTTNG_ERR* code.
 240  * On success, the caller is responsible for freeing the memory
 241  * allocated for "events".
 242  */
 243 static ssize_t list_events(struct agent_app *app, struct lttng_event **events)
 244 {
 245         int ret, i, len = 0, offset = 0;
 246         uint32_t nb_event;
 247         size_t data_size;
 248         struct lttng_event *tmp_events = NULL;
 249         struct lttcomm_agent_list_reply *reply = NULL;
 250         struct lttcomm_agent_list_reply_hdr reply_hdr;
 251
 252         assert(app);
 253         assert(app->sock);
 254         assert(events);
 255
 256         DBG2("Agent listing events for app pid: %d and socket %d", app->pid,
 257                         app->sock->fd);
 258
 259         ret = send_header(app->sock, 0, AGENT_CMD_LIST, 0);
 260         if (ret < 0) {
 261                 goto error_io;
 262         }
 263
 264         /* Get list header so we know how much we'll receive. */
 265         ret = recv_reply(app->sock, &reply_hdr, sizeof(reply_hdr));
 266         if (ret < 0) {
 267                 goto error_io;
 268         }
 269
 270         switch (be32toh(reply_hdr.ret_code)) {
 271         case AGENT_RET_CODE_SUCCESS:
 272                 data_size = be32toh(reply_hdr.data_size) + sizeof(*reply);
 273                 break;
 274         default:
 275                 ERR("Agent returned an unknown code: %" PRIu32,
 276                                 be32toh(reply_hdr.ret_code));
 277                 ret = LTTNG_ERR_FATAL;
 278                 goto error;
 279         }
 280
 281         reply = zmalloc(data_size);
 282         if (!reply) {
 283                 ret = LTTNG_ERR_NOMEM;
 284                 goto error;
 285         }
 286
 287         /* Get the list with the appropriate data size. */
 288         ret = recv_reply(app->sock, reply, data_size);
 289         if (ret < 0) {
 290                 goto error_io;
 291         }
 292
 293         nb_event = be32toh(reply->nb_event);
 294         tmp_events = zmalloc(sizeof(*tmp_events) * nb_event);
 295         if (!tmp_events) {
 296                 ret = LTTNG_ERR_NOMEM;
 297                 goto error;
 298         }
 299
 300         for (i = 0; i < nb_event; i++) {
 301                 offset += len;
 302                 strncpy(tmp_events[i].name, reply->payload + offset,
 303                                 sizeof(tmp_events[i].name));
 304                 tmp_events[i].pid = app->pid;
 305                 tmp_events[i].enabled = -1;
 306                 len = strlen(reply->payload + offset) + 1;
 307         }
 308
 309         *events = tmp_events;
 310
 311         free(reply);
 312         return nb_event;
 313
 314 error_io:
 315         ret = LTTNG_ERR_UST_LIST_FAIL;
 316 error:
 317         free(reply);
 318         free(tmp_events);
 319         return -ret;
 320
 321 }
 322
 323 /*
 324  * Internal enable agent event on a agent application. This function
 325  * communicates with the agent to enable a given event.
 326  *
 327  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 328  */
 329 static int enable_event(struct agent_app *app, struct agent_event *event)
 330 {
 331         int ret;
 332         uint64_t data_size;
 333         struct lttcomm_agent_enable msg;
 334         struct lttcomm_agent_generic_reply reply;
 335
 336         assert(app);
 337         assert(app->sock);
 338         assert(event);
 339
 340         DBG2("Agent enabling event %s for app pid: %d and socket %d", event->name,
 341                         app->pid, app->sock->fd);
 342
 343         data_size = sizeof(msg);
 344
 345         ret = send_header(app->sock, data_size, AGENT_CMD_ENABLE, 0);
 346         if (ret < 0) {
 347                 goto error_io;
 348         }
 349
 350         memset(&msg, 0, sizeof(msg));
 351         msg.loglevel_value = event->loglevel_value;
 352         msg.loglevel_type = event->loglevel_type;
 353         strncpy(msg.name, event->name, sizeof(msg.name));
 354         ret = send_payload(app->sock, &msg, sizeof(msg));
 355         if (ret < 0) {
 356                 goto error_io;
 357         }
 358
 359         ret = recv_reply(app->sock, &reply, sizeof(reply));
 360         if (ret < 0) {
 361                 goto error_io;
 362         }
 363
 364         switch (be32toh(reply.ret_code)) {
 365         case AGENT_RET_CODE_SUCCESS:
 366                 break;
 367         case AGENT_RET_CODE_UNKNOWN_NAME:
 368                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 369                 goto error;
 370         default:
 371                 ERR("Agent returned an unknown code: %" PRIu32,
 372                                 be32toh(reply.ret_code));
 373                 ret = LTTNG_ERR_FATAL;
 374                 goto error;
 375         }
 376
 377         return LTTNG_OK;
 378
 379 error_io:
 380         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 381 error:
 382         return ret;
 383 }
 384
 385 /*
 386  * Internal disable agent event call on a agent application. This function
 387  * communicates with the agent to disable a given event.
 388  *
 389  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 390  */
 391 static int disable_event(struct agent_app *app, struct agent_event *event)
 392 {
 393         int ret;
 394         uint64_t data_size;
 395         struct lttcomm_agent_disable msg;
 396         struct lttcomm_agent_generic_reply reply;
 397
 398         assert(app);
 399         assert(app->sock);
 400         assert(event);
 401
 402         DBG2("Agent disabling event %s for app pid: %d and socket %d", event->name,
 403                         app->pid, app->sock->fd);
 404
 405         data_size = sizeof(msg);
 406
 407         ret = send_header(app->sock, data_size, AGENT_CMD_DISABLE, 0);
 408         if (ret < 0) {
 409                 goto error_io;
 410         }
 411
 412         memset(&msg, 0, sizeof(msg));
 413         strncpy(msg.name, event->name, sizeof(msg.name));
 414         ret = send_payload(app->sock, &msg, sizeof(msg));
 415         if (ret < 0) {
 416                 goto error_io;
 417         }
 418
 419         ret = recv_reply(app->sock, &reply, sizeof(reply));
 420         if (ret < 0) {
 421                 goto error_io;
 422         }
 423
 424         switch (be32toh(reply.ret_code)) {
 425         case AGENT_RET_CODE_SUCCESS:
 426                 break;
 427         case AGENT_RET_CODE_UNKNOWN_NAME:
 428                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 429                 goto error;
 430         default:
 431                 ERR("Agent returned an unknown code: %" PRIu32,
 432                                 be32toh(reply.ret_code));
 433                 ret = LTTNG_ERR_FATAL;
 434                 goto error;
 435         }
 436
 437         return LTTNG_OK;
 438
 439 error_io:
 440         ret = LTTNG_ERR_UST_DISABLE_FAIL;
 441 error:
 442         return ret;
 443 }
 444
 445 /*
 446  * Send back the registration DONE command to a given agent application.
 447  *
 448  * Return 0 on success or else a negative value.
 449  */
 450 int agent_send_registration_done(struct agent_app *app)
 451 {
 452         assert(app);
 453         assert(app->sock);
 454
 455         DBG("Agent sending registration done to app socket %d", app->sock->fd);
 456
 457         return send_header(app->sock, 0, AGENT_CMD_REG_DONE, 0);
 458 }
 459
 460 /*
 461  * Enable agent event on every agent applications registered with the session
 462  * daemon.
 463  *
 464  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 465  */
 466 int agent_enable_event(struct agent_event *event,
 467                 enum lttng_domain_type domain)
 468 {
 469         int ret;
 470         struct agent_app *app;
 471         struct lttng_ht_iter iter;
 472
 473         assert(event);
 474
 475         rcu_read_lock();
 476
 477         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 478                         node.node) {
 479                 if (app->domain != domain) {
 480                         continue;
 481                 }
 482
 483                 /* Enable event on agent application through TCP socket. */
 484                 ret = enable_event(app, event);
 485                 if (ret != LTTNG_OK) {
 486                         goto error;
 487                 }
 488         }
 489
 490         event->enabled = 1;
 491         ret = LTTNG_OK;
 492
 493 error:
 494         rcu_read_unlock();
 495         return ret;
 496 }
 497
 498 /*
 499  * Disable agent event on every agent applications registered with the session
 500  * daemon.
 501  *
 502  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 503  */
 504 int agent_disable_event(struct agent_event *event,
 505                 enum lttng_domain_type domain)
 506 {
 507         int ret = LTTNG_OK;
 508         struct agent_app *app;
 509         struct lttng_ht_iter iter;
 510
 511         assert(event);
 512         if (!event->enabled) {
 513                 goto end;
 514         }
 515
 516         rcu_read_lock();
 517
 518         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 519                         node.node) {
 520                 if (app->domain != domain) {
 521                         continue;
 522                 }
 523
 524                 /* Enable event on agent application through TCP socket. */
 525                 ret = disable_event(app, event);
 526                 if (ret != LTTNG_OK) {
 527                         goto error;
 528                 }
 529         }
 530
 531         event->enabled = 0;
 532
 533 error:
 534         rcu_read_unlock();
 535 end:
 536         return ret;
 537 }
 538
 539 /*
 540  * Ask every agent for the list of possible event. Events is allocated with the
 541  * events of every agent application.
 542  *
 543  * Return the number of events or else a negative value.
 544  */
 545 int agent_list_events(struct lttng_event **events,
 546                 enum lttng_domain_type domain)
 547 {
 548         int ret;
 549         size_t nbmem, count = 0;
 550         struct agent_app *app;
 551         struct lttng_event *tmp_events = NULL;
 552         struct lttng_ht_iter iter;
 553
 554         assert(events);
 555
 556         DBG2("Agent listing events for domain %d", domain);
 557
 558         nbmem = UST_APP_EVENT_LIST_SIZE;
 559         tmp_events = zmalloc(nbmem * sizeof(*tmp_events));
 560         if (!tmp_events) {
 561                 PERROR("zmalloc agent list events");
 562                 ret = -ENOMEM;
 563                 goto error;
 564         }
 565
 566         rcu_read_lock();
 567         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 568                         node.node) {
 569                 ssize_t nb_ev;
 570                 struct lttng_event *agent_events;
 571
 572                 /* Skip domain not asked by the list. */
 573                 if (app->domain != domain) {
 574                         continue;
 575                 }
 576
 577                 nb_ev = list_events(app, &agent_events);
 578                 if (nb_ev < 0) {
 579                         ret = nb_ev;
 580                         goto error_unlock;
 581                 }
 582
 583                 if (count + nb_ev > nbmem) {
 584                         /* In case the realloc fails, we free the memory */
 585                         struct lttng_event *new_tmp_events;
 586                         size_t new_nbmem;
 587
 588                         new_nbmem = max_t(size_t, count + nb_ev, nbmem << 1);
 589                         DBG2("Reallocating agent event list from %zu to %zu entries",
 590                                         nbmem, new_nbmem);
 591                         new_tmp_events = realloc(tmp_events,
 592                                 new_nbmem * sizeof(*new_tmp_events));
 593                         if (!new_tmp_events) {
 594                                 PERROR("realloc agent events");
 595                                 ret = -ENOMEM;
 596                                 free(agent_events);
 597                                 goto error_unlock;
 598                         }
 599                         /* Zero the new memory */
 600                         memset(new_tmp_events + nbmem, 0,
 601                                 (new_nbmem - nbmem) * sizeof(*new_tmp_events));
 602                         nbmem = new_nbmem;
 603                         tmp_events = new_tmp_events;
 604                 }
 605                 memcpy(tmp_events + count, agent_events,
 606                         nb_ev * sizeof(*tmp_events));
 607                 free(agent_events);
 608                 count += nb_ev;
 609         }
 610         rcu_read_unlock();
 611
 612         ret = count;
 613         *events = tmp_events;
 614         return ret;
 615
 616 error_unlock:
 617         rcu_read_unlock();
 618 error:
 619         free(tmp_events);
 620         return ret;
 621 }
 622
 623 /*
 624  * Create a agent app object using the given PID.
 625  *
 626  * Return newly allocated object or else NULL on error.
 627  */
 628 struct agent_app *agent_create_app(pid_t pid, enum lttng_domain_type domain,
 629                 struct lttcomm_sock *sock)
 630 {
 631         struct agent_app *app;
 632
 633         assert(sock);
 634
 635         app = zmalloc(sizeof(*app));
 636         if (!app) {
 637                 PERROR("zmalloc agent create");
 638                 goto error;
 639         }
 640
 641         app->pid = pid;
 642         app->domain = domain;
 643         app->sock = sock;
 644         lttng_ht_node_init_ulong(&app->node, (unsigned long) app->sock->fd);
 645
 646 error:
 647         return app;
 648 }
 649
 650 /*
 651  * Lookup agent app by socket in the global hash table.
 652  *
 653  * RCU read side lock MUST be acquired.
 654  *
 655  * Return object if found else NULL.
 656  */
 657 struct agent_app *agent_find_app_by_sock(int sock)
 658 {
 659         struct lttng_ht_node_ulong *node;
 660         struct lttng_ht_iter iter;
 661         struct agent_app *app;
 662
 663         assert(sock >= 0);
 664
 665         lttng_ht_lookup(agent_apps_ht_by_sock, (void *)((unsigned long) sock), &iter);
 666         node = lttng_ht_iter_get_node_ulong(&iter);
 667         if (node == NULL) {
 668                 goto error;
 669         }
 670         app = caa_container_of(node, struct agent_app, node);
 671
 672         DBG3("Agent app pid %d found by sock %d.", app->pid, sock);
 673         return app;
 674
 675 error:
 676         DBG3("Agent app NOT found by sock %d.", sock);
 677         return NULL;
 678 }
 679
 680 /*
 681  * Add agent application object to the global hash table.
 682  */
 683 void agent_add_app(struct agent_app *app)
 684 {
 685         assert(app);
 686
 687         DBG3("Agent adding app sock: %d and pid: %d to ht", app->sock->fd, app->pid);
 688
 689         rcu_read_lock();
 690         lttng_ht_add_unique_ulong(agent_apps_ht_by_sock, &app->node);
 691         rcu_read_unlock();
 692 }
 693
 694 /*
 695  * Delete agent application from the global hash table.
 696  *
 697  * rcu_read_lock() must be held by the caller.
 698  */
 699 void agent_delete_app(struct agent_app *app)
 700 {
 701         int ret;
 702         struct lttng_ht_iter iter;
 703
 704         assert(app);
 705
 706         DBG3("Agent deleting app pid: %d and sock: %d", app->pid, app->sock->fd);
 707
 708         iter.iter.node = &app->node.node;
 709         ret = lttng_ht_del(agent_apps_ht_by_sock, &iter);
 710         assert(!ret);
 711 }
 712
 713 /*
 714  * Destroy a agent application object by detaching it from its corresponding
 715  * UST app if one is connected by closing the socket. Finally, perform a
 716  * delayed memory reclaim.
 717  */
 718 void agent_destroy_app(struct agent_app *app)
 719 {
 720         assert(app);
 721
 722         if (app->sock) {
 723                 app->sock->ops->close(app->sock);
 724                 lttcomm_destroy_sock(app->sock);
 725         }
 726
 727         call_rcu(&app->node.head, destroy_app_agent_rcu);
 728 }
 729
 730 /*
 731  * Initialize an already allocated agent object.
 732  *
 733  * Return 0 on success or else a negative errno value.
 734  */
 735 int agent_init(struct agent *agt)
 736 {
 737         int ret;
 738
 739         assert(agt);
 740
 741         agt->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 742         if (!agt->events) {
 743                 ret = -ENOMEM;
 744                 goto error;
 745         }
 746         lttng_ht_node_init_u64(&agt->node, agt->domain);
 747
 748         return 0;
 749
 750 error:
 751         return ret;
 752 }
 753
 754 /*
 755  * Add agent object to the given hash table.
 756  */
 757 void agent_add(struct agent *agt, struct lttng_ht *ht)
 758 {
 759         assert(agt);
 760         assert(ht);
 761
 762         DBG3("Agent adding from domain %d", agt->domain);
 763
 764         rcu_read_lock();
 765         lttng_ht_add_unique_u64(ht, &agt->node);
 766         rcu_read_unlock();
 767 }
 768
 769 /*
 770  * Create an agent object for the given domain.
 771  *
 772  * Return the allocated agent or NULL on error.
 773  */
 774 struct agent *agent_create(enum lttng_domain_type domain)
 775 {
 776         int ret;
 777         struct agent *agt;
 778
 779         agt = zmalloc(sizeof(*agt));
 780         if (!agt) {
 781                 goto error;
 782         }
 783         agt->domain = domain;
 784
 785         ret = agent_init(agt);
 786         if (ret < 0) {
 787                 free(agt);
 788                 agt = NULL;
 789                 goto error;
 790         }
 791
 792 error:
 793         return agt;
 794 }
 795
 796 /*
 797  * Create a newly allocated agent event data structure.
 798  * Ownership of filter_expression is taken.
 799  *
 800  * Return a new object else NULL on error.
 801  */
 802 struct agent_event *agent_create_event(const char *name,
 803                 enum lttng_loglevel_type loglevel_type, int loglevel_value,
 804                 struct lttng_filter_bytecode *filter, char *filter_expression)
 805 {
 806         struct agent_event *event = NULL;
 807
 808         DBG3("Agent create new event with name %s, loglevel type %d, \
 809                         loglevel value %d and filter %s",
 810                         name, loglevel_type, loglevel_value,
 811                         filter_expression ? filter_expression : "NULL");
 812
 813         if (!name) {
 814                 ERR("Failed to create agent event; no name provided.");
 815                 goto error;
 816         }
 817
 818         event = zmalloc(sizeof(*event));
 819         if (!event) {
 820                 goto error;
 821         }
 822
 823         strncpy(event->name, name, sizeof(event->name));
 824         event->name[sizeof(event->name) - 1] = '\0';
 825         lttng_ht_node_init_str(&event->node, event->name);
 826
 827         event->loglevel_value = loglevel_value;
 828         event->loglevel_type = loglevel_type;
 829         event->filter = filter;
 830         event->filter_expression = filter_expression;
 831 error:
 832         return event;
 833 }
 834
 835 /*
 836  * Unique add of a agent event to an agent object.
 837  */
 838 void agent_add_event(struct agent_event *event, struct agent *agt)
 839 {
 840         assert(event);
 841         assert(agt);
 842         assert(agt->events);
 843
 844         DBG3("Agent adding event %s", event->name);
 845
 846         rcu_read_lock();
 847         add_unique_agent_event(agt->events, event);
 848         rcu_read_unlock();
 849         agt->being_used = 1;
 850 }
 851
 852 /*
 853  * Find multiple agent events sharing the given name.
 854  *
 855  * RCU read side lock MUST be acquired. It must be held for the
 856  * duration of the iteration.
 857  *
 858  * Sets the given iterator.
 859  */
 860 void agent_find_events_by_name(const char *name, struct agent *agt,
 861                 struct lttng_ht_iter* iter)
 862 {
 863         struct lttng_ht *ht;
 864         struct agent_ht_key key;
 865
 866         assert(name);
 867         assert(agt);
 868         assert(agt->events);
 869         assert(iter);
 870
 871         ht = agt->events;
 872         key.name = name;
 873
 874         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 875                         ht_match_event_by_name, &key, &iter->iter);
 876 }
 877
 878 /*
 879  * Get the next agent event duplicate by name. This should be called
 880  * after a call to agent_find_events_by_name() to iterate on events.
 881  *
 882  * The RCU read lock must be held during the iteration and for as long
 883  * as the object the iterator points to remains in use.
 884  */
 885 void agent_event_next_duplicate(const char *name,
 886                 struct agent *agt, struct lttng_ht_iter* iter)
 887 {
 888         struct agent_ht_key key;
 889
 890         key.name = name;
 891
 892         cds_lfht_next_duplicate(agt->events->ht, ht_match_event_by_name,
 893                 &key, &iter->iter);
 894 }
 895
 896 /*
 897  * Find a agent event in the given agent using name, loglevel and filter.
 898  *
 899  * RCU read side lock MUST be acquired.
 900  *
 901  * Return object if found else NULL.
 902  */
 903 struct agent_event *agent_find_event(const char *name,
 904                 enum lttng_loglevel_type loglevel_type, int loglevel_value,
 905                 char *filter_expression, struct agent *agt)
 906 {
 907         struct lttng_ht_node_str *node;
 908         struct lttng_ht_iter iter;
 909         struct lttng_ht *ht;
 910         struct agent_ht_key key;
 911
 912         assert(name);
 913         assert(agt);
 914         assert(agt->events);
 915
 916         ht = agt->events;
 917         key.name = name;
 918         key.loglevel_value = loglevel_value;
 919         key.loglevel_type = loglevel_type;
 920         key.filter_expression = filter_expression;
 921
 922         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 923                         ht_match_event, &key, &iter.iter);
 924         node = lttng_ht_iter_get_node_str(&iter);
 925         if (node == NULL) {
 926                 goto error;
 927         }
 928
 929         DBG3("Agent event found %s.", name);
 930         return caa_container_of(node, struct agent_event, node);
 931
 932 error:
 933         DBG3("Agent event NOT found %s.", name);
 934         return NULL;
 935 }
 936
 937 /*
 938  * Free given agent event. This event must not be globally visible at this
 939  * point (only expected to be used on failure just after event creation). After
 940  * this call, the pointer is not usable anymore.
 941  */
 942 void agent_destroy_event(struct agent_event *event)
 943 {
 944         assert(event);
 945
 946         free(event->filter);
 947         free(event->filter_expression);
 948         free(event->exclusion);
 949         free(event);
 950 }
 951
 952 /*
 953  * Destroy an agent completely.
 954  */
 955 void agent_destroy(struct agent *agt)
 956 {
 957         struct lttng_ht_node_str *node;
 958         struct lttng_ht_iter iter;
 959
 960         assert(agt);
 961
 962         DBG3("Agent destroy");
 963
 964         /*
 965          * Just ignore if no events hash table exists. This is possible if for
 966          * instance an agent object was allocated but not initialized.
 967          */
 968         if (!agt->events) {
 969                 return;
 970         }
 971
 972         rcu_read_lock();
 973         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, node, node) {
 974                 int ret;
 975                 struct agent_event *event;
 976
 977                 /*
 978                  * When destroying an event, we have to try to disable it on the agent
 979                  * side so the event stops generating data. The return value is not
 980                  * important since we have to continue anyway destroying the object.
 981                  */
 982                 event = caa_container_of(node, struct agent_event, node);
 983                 (void) agent_disable_event(event, agt->domain);
 984
 985                 ret = lttng_ht_del(agt->events, &iter);
 986                 assert(!ret);
 987                 call_rcu(&node->head, destroy_event_agent_rcu);
 988         }
 989         rcu_read_unlock();
 990
 991         ht_cleanup_push(agt->events);
 992         free(agt);
 993 }
 994
 995 /*
 996  * Allocate agent_apps_ht_by_sock.
 997  */
 998 int agent_app_ht_alloc(void)
 999 {
1000         int ret = 0;
1001
1002         agent_apps_ht_by_sock = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
1003         if (!agent_apps_ht_by_sock) {
1004                 ret = -1;
1005         }
1006
1007         return ret;
1008 }
1009
1010 /*
1011  * Destroy a agent application by socket.
1012  */
1013 void agent_destroy_app_by_sock(int sock)
1014 {
1015         struct agent_app *app;
1016
1017         assert(sock >= 0);
1018
1019         /*
1020          * Not finding an application is a very important error that should NEVER
1021          * happen. The hash table deletion is ONLY done through this call when the
1022          * main sessiond thread is torn down.
1023          */
1024         rcu_read_lock();
1025         app = agent_find_app_by_sock(sock);
1026         assert(app);
1027
1028         /* RCU read side lock is assumed to be held by this function. */
1029         agent_delete_app(app);
1030
1031         /* The application is freed in a RCU call but the socket is closed here. */
1032         agent_destroy_app(app);
1033         rcu_read_unlock();
1034 }
1035
1036 /*
1037  * Clean-up the agent app hash table and destroy it.
1038  */
1039 void agent_app_ht_clean(void)
1040 {
1041         struct lttng_ht_node_ulong *node;
1042         struct lttng_ht_iter iter;
1043
1044         if (!agent_apps_ht_by_sock) {
1045                 return;
1046         }
1047         rcu_read_lock();
1048         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, node, node) {
1049                 struct agent_app *app;
1050
1051                 app = caa_container_of(node, struct agent_app, node);
1052                 agent_destroy_app_by_sock(app->sock->fd);
1053         }
1054         rcu_read_unlock();
1055
1056         lttng_ht_destroy(agent_apps_ht_by_sock);
1057 }
1058
1059 /*
1060  * Update a agent application (given socket) using the given agent.
1061  *
1062  * Note that this function is most likely to be used with a tracing session
1063  * thus the caller should make sure to hold the appropriate lock(s).
1064  */
1065 void agent_update(struct agent *agt, int sock)
1066 {
1067         int ret;
1068         struct agent_app *app;
1069         struct agent_event *event;
1070         struct lttng_ht_iter iter;
1071
1072         assert(agt);
1073         assert(sock >= 0);
1074
1075         DBG("Agent updating app socket %d", sock);
1076
1077         rcu_read_lock();
1078         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, event, node.node) {
1079                 /* Skip event if disabled. */
1080                 if (!event->enabled) {
1081                         continue;
1082                 }
1083
1084                 app = agent_find_app_by_sock(sock);
1085                 /*
1086                  * We are in the registration path thus if the application is gone,
1087                  * there is a serious code flow error.
1088                  */
1089                 assert(app);
1090
1091                 ret = enable_event(app, event);
1092                 if (ret != LTTNG_OK) {
1093                         DBG2("Agent update unable to enable event %s on app pid: %d sock %d",
1094                                         event->name, app->pid, app->sock->fd);
1095                         /* Let's try the others here and don't assume the app is dead. */
1096                         continue;
1097                 }
1098         }
1099         rcu_read_unlock();
1100 }