liblttng-ust/lttng-ust-abi.c

   1 /*
   2  * lttng-ust-abi.c
   3  *
   4  * LTTng UST ABI
   5  *
   6  * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  *
  22  *
  23  * Mimic system calls for:
  24  * - session creation, returns an object descriptor or failure.
  25  *   - channel creation, returns an object descriptor or failure.
  26  *     - Operates on a session object descriptor
  27  *     - Takes all channel options as parameters.
  28  *   - stream get, returns an object descriptor or failure.
  29  *     - Operates on a channel object descriptor.
  30  *   - stream notifier get, returns an object descriptor or failure.
  31  *     - Operates on a channel object descriptor.
  32  *   - event creation, returns an object descriptor or failure.
  33  *     - Operates on a channel object descriptor
  34  *     - Takes an event name as parameter
  35  *     - Takes an instrumentation source as parameter
  36  *       - e.g. tracepoints, dynamic_probes...
  37  *     - Takes instrumentation source specific arguments.
  38  */
  39
  40 #include <lttng/ust-abi.h>
  41 #include <lttng/ust-error.h>
  42 #include <urcu/compiler.h>
  43 #include <urcu/list.h>
  44 #include <lttng/ust-events.h>
  45 #include <lttng/ust-version.h>
  46 #include <lttng/tracepoint.h>
  47 #include "tracepoint-internal.h"
  48 #include <usterr-signal-safe.h>
  49 #include <helper.h>
  50 #include "lttng-tracer.h"
  51 #include "../libringbuffer/shm.h"
  52 #include "../libringbuffer/frontend_types.h"
  53
  54 #define OBJ_NAME_LEN    16
  55
  56 static int lttng_ust_abi_close_in_progress;
  57
  58 static
  59 int lttng_abi_tracepoint_list(void *owner);
  60 static
  61 int lttng_abi_tracepoint_field_list(void *owner);
  62
  63 /*
  64  * Object descriptor table. Should be protected from concurrent access
  65  * by the caller.
  66  */
  67
  68 struct lttng_ust_obj {
  69         union {
  70                 struct {
  71                         void *private_data;
  72                         const struct lttng_ust_objd_ops *ops;
  73                         int f_count;
  74                         int owner_ref;  /* has ref from owner */
  75                         void *owner;
  76                         char name[OBJ_NAME_LEN];
  77                 } s;
  78                 int freelist_next;      /* offset freelist. end is -1. */
  79         } u;
  80 };
  81
  82 struct lttng_ust_objd_table {
  83         struct lttng_ust_obj *array;
  84         unsigned int len, allocated_len;
  85         int freelist_head;              /* offset freelist head. end is -1 */
  86 };
  87
  88 static struct lttng_ust_objd_table objd_table = {
  89         .freelist_head = -1,
  90 };
  91
  92 static
  93 int objd_alloc(void *private_data, const struct lttng_ust_objd_ops *ops,
  94                 void *owner, const char *name)
  95 {
  96         struct lttng_ust_obj *obj;
  97
  98         if (objd_table.freelist_head != -1) {
  99                 obj = &objd_table.array[objd_table.freelist_head];
 100                 objd_table.freelist_head = obj->u.freelist_next;
 101                 goto end;
 102         }
 103
 104         if (objd_table.len >= objd_table.allocated_len) {
 105                 unsigned int new_allocated_len, old_allocated_len;
 106                 struct lttng_ust_obj *new_table, *old_table;
 107
 108                 old_allocated_len = objd_table.allocated_len;
 109                 old_table = objd_table.array;
 110                 if (!old_allocated_len)
 111                         new_allocated_len = 1;
 112                 else
 113                         new_allocated_len = old_allocated_len << 1;
 114                 new_table = zmalloc(sizeof(struct lttng_ust_obj) * new_allocated_len);
 115                 if (!new_table)
 116                         return -ENOMEM;
 117                 memcpy(new_table, old_table,
 118                        sizeof(struct lttng_ust_obj) * old_allocated_len);
 119                 free(old_table);
 120                 objd_table.array = new_table;
 121                 objd_table.allocated_len = new_allocated_len;
 122         }
 123         obj = &objd_table.array[objd_table.len];
 124         objd_table.len++;
 125 end:
 126         obj->u.s.private_data = private_data;
 127         obj->u.s.ops = ops;
 128         obj->u.s.f_count = 2;   /* count == 1 : object is allocated */
 129                                 /* count == 2 : allocated + hold ref */
 130         obj->u.s.owner_ref = 1; /* One owner reference */
 131         obj->u.s.owner = owner;
 132         strncpy(obj->u.s.name, name, OBJ_NAME_LEN);
 133         obj->u.s.name[OBJ_NAME_LEN - 1] = '\0';
 134         return obj - objd_table.array;
 135 }
 136
 137 static
 138 struct lttng_ust_obj *_objd_get(int id)
 139 {
 140         if (id >= objd_table.len)
 141                 return NULL;
 142         if (!objd_table.array[id].u.s.f_count)
 143                 return NULL;
 144         return &objd_table.array[id];
 145 }
 146
 147 static
 148 void *objd_private(int id)
 149 {
 150         struct lttng_ust_obj *obj = _objd_get(id);
 151         assert(obj);
 152         return obj->u.s.private_data;
 153 }
 154
 155 static
 156 void objd_set_private(int id, void *private_data)
 157 {
 158         struct lttng_ust_obj *obj = _objd_get(id);
 159         assert(obj);
 160         obj->u.s.private_data = private_data;
 161 }
 162
 163 const struct lttng_ust_objd_ops *objd_ops(int id)
 164 {
 165         struct lttng_ust_obj *obj = _objd_get(id);
 166
 167         if (!obj)
 168                 return NULL;
 169         return obj->u.s.ops;
 170 }
 171
 172 static
 173 void objd_free(int id)
 174 {
 175         struct lttng_ust_obj *obj = _objd_get(id);
 176
 177         assert(obj);
 178         obj->u.freelist_next = objd_table.freelist_head;
 179         objd_table.freelist_head = obj - objd_table.array;
 180         assert(obj->u.s.f_count == 1);
 181         obj->u.s.f_count = 0;   /* deallocated */
 182 }
 183
 184 static
 185 void objd_ref(int id)
 186 {
 187         struct lttng_ust_obj *obj = _objd_get(id);
 188         obj->u.s.f_count++;
 189 }
 190
 191 int lttng_ust_objd_unref(int id, int is_owner)
 192 {
 193         struct lttng_ust_obj *obj = _objd_get(id);
 194
 195         if (!obj)
 196                 return -EINVAL;
 197         if (obj->u.s.f_count == 1) {
 198                 ERR("Reference counting error\n");
 199                 return -EINVAL;
 200         }
 201         if (is_owner) {
 202                 if (!obj->u.s.owner_ref) {
 203                         ERR("Error decrementing owner reference");
 204                         return -EINVAL;
 205                 }
 206                 obj->u.s.owner_ref--;
 207         }
 208         if ((--obj->u.s.f_count) == 1) {
 209                 const struct lttng_ust_objd_ops *ops = objd_ops(id);
 210
 211                 if (ops->release)
 212                         ops->release(id);
 213                 objd_free(id);
 214         }
 215         return 0;
 216 }
 217
 218 static
 219 void objd_table_destroy(void)
 220 {
 221         int i;
 222
 223         for (i = 0; i < objd_table.allocated_len; i++) {
 224                 struct lttng_ust_obj *obj;
 225
 226                 obj = _objd_get(i);
 227                 if (!obj)
 228                         continue;
 229                 if (!obj->u.s.owner_ref)
 230                         continue;       /* only unref owner ref. */
 231                 (void) lttng_ust_objd_unref(i, 1);
 232         }
 233         free(objd_table.array);
 234         objd_table.array = NULL;
 235         objd_table.len = 0;
 236         objd_table.allocated_len = 0;
 237         objd_table.freelist_head = -1;
 238 }
 239
 240 const char *lttng_ust_obj_get_name(int id)
 241 {
 242         struct lttng_ust_obj *obj = _objd_get(id);
 243
 244         if (!obj)
 245                 return NULL;
 246         return obj->u.s.name;
 247 }
 248
 249 void lttng_ust_objd_table_owner_cleanup(void *owner)
 250 {
 251         int i;
 252
 253         for (i = 0; i < objd_table.allocated_len; i++) {
 254                 struct lttng_ust_obj *obj;
 255
 256                 obj = _objd_get(i);
 257                 if (!obj)
 258                         continue;
 259                 if (!obj->u.s.owner)
 260                         continue;       /* skip root handles */
 261                 if (!obj->u.s.owner_ref)
 262                         continue;       /* only unref owner ref. */
 263                 if (obj->u.s.owner == owner)
 264                         (void) lttng_ust_objd_unref(i, 1);
 265         }
 266 }
 267
 268 /*
 269  * This is LTTng's own personal way to create an ABI for sessiond.
 270  * We send commands over a socket.
 271  */
 272
 273 static const struct lttng_ust_objd_ops lttng_ops;
 274 static const struct lttng_ust_objd_ops lttng_session_ops;
 275 static const struct lttng_ust_objd_ops lttng_channel_ops;
 276 static const struct lttng_ust_objd_ops lttng_enabler_ops;
 277 static const struct lttng_ust_objd_ops lttng_tracepoint_list_ops;
 278 static const struct lttng_ust_objd_ops lttng_tracepoint_field_list_ops;
 279
 280 int lttng_abi_create_root_handle(void)
 281 {
 282         int root_handle;
 283
 284         /* root handles have NULL owners */
 285         root_handle = objd_alloc(NULL, &lttng_ops, NULL, "root");
 286         return root_handle;
 287 }
 288
 289 static
 290 int lttng_is_channel_ready(struct lttng_channel *lttng_chan)
 291 {
 292         struct channel *chan;
 293         unsigned int nr_streams, exp_streams;
 294
 295         chan = lttng_chan->chan;
 296         nr_streams = channel_handle_get_nr_streams(lttng_chan->handle);
 297         exp_streams = chan->nr_streams;
 298         return nr_streams == exp_streams;
 299 }
 300
 301 static
 302 int lttng_abi_create_session(void *owner)
 303 {
 304         struct lttng_session *session;
 305         int session_objd, ret;
 306
 307         session = lttng_session_create();
 308         if (!session)
 309                 return -ENOMEM;
 310         session_objd = objd_alloc(session, &lttng_session_ops, owner, "session");
 311         if (session_objd < 0) {
 312                 ret = session_objd;
 313                 goto objd_error;
 314         }
 315         session->objd = session_objd;
 316         session->owner = owner;
 317         return session_objd;
 318
 319 objd_error:
 320         lttng_session_destroy(session);
 321         return ret;
 322 }
 323
 324 static
 325 long lttng_abi_tracer_version(int objd,
 326         struct lttng_ust_tracer_version *v)
 327 {
 328         v->major = LTTNG_UST_MAJOR_VERSION;
 329         v->minor = LTTNG_UST_MINOR_VERSION;
 330         v->patchlevel = LTTNG_UST_PATCHLEVEL_VERSION;
 331         return 0;
 332 }
 333
 334 static
 335 long lttng_abi_add_context(int objd,
 336         struct lttng_ust_context *context_param,
 337         struct lttng_ctx **ctx, struct lttng_session *session)
 338 {
 339         return lttng_attach_context(context_param, ctx, session);
 340 }
 341
 342 /**
 343  *      lttng_cmd - lttng control through socket commands
 344  *
 345  *      @objd: the object descriptor
 346  *      @cmd: the command
 347  *      @arg: command arg
 348  *      @uargs: UST arguments (internal)
 349  *      @owner: objd owner
 350  *
 351  *      This descriptor implements lttng commands:
 352  *      LTTNG_UST_SESSION
 353  *              Returns a LTTng trace session object descriptor
 354  *      LTTNG_UST_TRACER_VERSION
 355  *              Returns the LTTng kernel tracer version
 356  *      LTTNG_UST_TRACEPOINT_LIST
 357  *              Returns a file descriptor listing available tracepoints
 358  *      LTTNG_UST_TRACEPOINT_FIELD_LIST
 359  *              Returns a file descriptor listing available tracepoint fields
 360  *      LTTNG_UST_WAIT_QUIESCENT
 361  *              Returns after all previously running probes have completed
 362  *
 363  * The returned session will be deleted when its file descriptor is closed.
 364  */
 365 static
 366 long lttng_cmd(int objd, unsigned int cmd, unsigned long arg,
 367         union ust_args *uargs, void *owner)
 368 {
 369         switch (cmd) {
 370         case LTTNG_UST_SESSION:
 371                 return lttng_abi_create_session(owner);
 372         case LTTNG_UST_TRACER_VERSION:
 373                 return lttng_abi_tracer_version(objd,
 374                                 (struct lttng_ust_tracer_version *) arg);
 375         case LTTNG_UST_TRACEPOINT_LIST:
 376                 return lttng_abi_tracepoint_list(owner);
 377         case LTTNG_UST_TRACEPOINT_FIELD_LIST:
 378                 return lttng_abi_tracepoint_field_list(owner);
 379         case LTTNG_UST_WAIT_QUIESCENT:
 380                 synchronize_trace();
 381                 return 0;
 382         default:
 383                 return -EINVAL;
 384         }
 385 }
 386
 387 static const struct lttng_ust_objd_ops lttng_ops = {
 388         .cmd = lttng_cmd,
 389 };
 390
 391 int lttng_abi_map_channel(int session_objd,
 392                 struct lttng_ust_channel *ust_chan,
 393                 union ust_args *uargs,
 394                 void *owner)
 395 {
 396         struct lttng_session *session = objd_private(session_objd);
 397         const char *transport_name;
 398         const struct lttng_transport *transport;
 399         const char *chan_name;
 400         int chan_objd;
 401         struct lttng_ust_shm_handle *channel_handle;
 402         struct lttng_channel *lttng_chan;
 403         struct channel *chan;
 404         struct lttng_ust_lib_ring_buffer_config *config;
 405         void *chan_data;
 406         int wakeup_fd;
 407         uint64_t len;
 408         int ret;
 409         enum lttng_ust_chan_type type;
 410
 411         chan_data = uargs->channel.chan_data;
 412         wakeup_fd = uargs->channel.wakeup_fd;
 413         len = ust_chan->len;
 414         type = ust_chan->type;
 415
 416         switch (type) {
 417         case LTTNG_UST_CHAN_PER_CPU:
 418                 break;
 419         default:
 420                 ret = -EINVAL;
 421                 goto invalid;
 422         }
 423
 424         if (session->been_active) {
 425                 ret = -EBUSY;
 426                 goto active;    /* Refuse to add channel to active session */
 427         }
 428
 429         channel_handle = channel_handle_create(chan_data, len, wakeup_fd);
 430         if (!channel_handle) {
 431                 ret = -EINVAL;
 432                 goto handle_error;
 433         }
 434
 435         chan = shmp(channel_handle, channel_handle->chan);
 436         assert(chan);
 437         chan->handle = channel_handle;
 438         config = &chan->backend.config;
 439         lttng_chan = channel_get_private(chan);
 440         if (!lttng_chan) {
 441                 ret = -EINVAL;
 442                 goto alloc_error;
 443         }
 444
 445         /* Lookup transport name */
 446         switch (type) {
 447         case LTTNG_UST_CHAN_PER_CPU:
 448                 if (config->output == RING_BUFFER_MMAP) {
 449                         if (config->mode == RING_BUFFER_OVERWRITE) {
 450                                 if (config->wakeup == RING_BUFFER_WAKEUP_BY_WRITER) {
 451                                         transport_name = "relay-overwrite-mmap";
 452                                 } else {
 453                                         transport_name = "relay-overwrite-rt-mmap";
 454                                 }
 455                         } else {
 456                                 if (config->wakeup == RING_BUFFER_WAKEUP_BY_WRITER) {
 457                                         transport_name = "relay-discard-mmap";
 458                                 } else {
 459                                         transport_name = "relay-discard-rt-mmap";
 460                                 }
 461                         }
 462                 } else {
 463                         ret = -EINVAL;
 464                         goto notransport;
 465                 }
 466                 chan_name = "channel";
 467                 break;
 468         default:
 469                 transport_name = "<unknown>";
 470                 chan_name = "<unknown>";
 471                 ret = -EINVAL;
 472                 goto notransport;
 473         }
 474         transport = lttng_transport_find(transport_name);
 475         if (!transport) {
 476                 DBG("LTTng transport %s not found\n",
 477                        transport_name);
 478                 ret = -EINVAL;
 479                 goto notransport;
 480         }
 481
 482         chan_objd = objd_alloc(NULL, &lttng_channel_ops, owner, chan_name);
 483         if (chan_objd < 0) {
 484                 ret = chan_objd;
 485                 goto objd_error;
 486         }
 487
 488         /* Initialize our lttng chan */
 489         lttng_chan->chan = chan;
 490         lttng_chan->tstate = 1;
 491         lttng_chan->enabled = 1;
 492         lttng_chan->ctx = NULL;
 493         lttng_chan->session = session;
 494         lttng_chan->ops = &transport->ops;
 495         memcpy(&lttng_chan->chan->backend.config,
 496                 transport->client_config,
 497                 sizeof(lttng_chan->chan->backend.config));
 498         cds_list_add(&lttng_chan->node, &session->chan_head);
 499         lttng_chan->header_type = 0;
 500         lttng_chan->handle = channel_handle;
 501         lttng_chan->type = type;
 502
 503         /*
 504          * We tolerate no failure path after channel creation. It will stay
 505          * invariant for the rest of the session.
 506          */
 507         objd_set_private(chan_objd, lttng_chan);
 508         lttng_chan->objd = chan_objd;
 509         /* The channel created holds a reference on the session */
 510         objd_ref(session_objd);
 511         return chan_objd;
 512
 513         /* error path after channel was created */
 514 objd_error:
 515 notransport:
 516         free(lttng_chan);
 517 alloc_error:
 518         channel_destroy(chan, channel_handle, 0);
 519         return ret;
 520
 521         /*
 522          * error path before channel creation (owning chan_data and
 523          * wakeup_fd).
 524          */
 525 handle_error:
 526 active:
 527 invalid:
 528         {
 529                 int close_ret;
 530
 531                 close_ret = close(wakeup_fd);
 532                 if (close_ret) {
 533                         PERROR("close");
 534                 }
 535         }
 536         free(chan_data);
 537         return ret;
 538 }
 539
 540 /**
 541  *      lttng_session_cmd - lttng session object command
 542  *
 543  *      @obj: the object
 544  *      @cmd: the command
 545  *      @arg: command arg
 546  *      @uargs: UST arguments (internal)
 547  *      @owner: objd owner
 548  *
 549  *      This descriptor implements lttng commands:
 550  *      LTTNG_UST_CHANNEL
 551  *              Returns a LTTng channel object descriptor
 552  *      LTTNG_UST_ENABLE
 553  *              Enables tracing for a session (weak enable)
 554  *      LTTNG_UST_DISABLE
 555  *              Disables tracing for a session (strong disable)
 556  *
 557  * The returned channel will be deleted when its file descriptor is closed.
 558  */
 559 static
 560 long lttng_session_cmd(int objd, unsigned int cmd, unsigned long arg,
 561         union ust_args *uargs, void *owner)
 562 {
 563         struct lttng_session *session = objd_private(objd);
 564
 565         switch (cmd) {
 566         case LTTNG_UST_CHANNEL:
 567                 return lttng_abi_map_channel(objd,
 568                                 (struct lttng_ust_channel *) arg,
 569                                 uargs, owner);
 570         case LTTNG_UST_SESSION_START:
 571         case LTTNG_UST_ENABLE:
 572                 return lttng_session_enable(session);
 573         case LTTNG_UST_SESSION_STOP:
 574         case LTTNG_UST_DISABLE:
 575                 return lttng_session_disable(session);
 576         default:
 577                 return -EINVAL;
 578         }
 579 }
 580
 581 /*
 582  * Called when the last file reference is dropped.
 583  *
 584  * Big fat note: channels and events are invariant for the whole session after
 585  * their creation. So this session destruction also destroys all channel and
 586  * event structures specific to this session (they are not destroyed when their
 587  * individual file is released).
 588  */
 589 static
 590 int lttng_release_session(int objd)
 591 {
 592         struct lttng_session *session = objd_private(objd);
 593
 594         if (session) {
 595                 lttng_session_destroy(session);
 596                 return 0;
 597         } else {
 598                 return -EINVAL;
 599         }
 600 }
 601
 602 static const struct lttng_ust_objd_ops lttng_session_ops = {
 603         .release = lttng_release_session,
 604         .cmd = lttng_session_cmd,
 605 };
 606
 607 static
 608 long lttng_tracepoint_list_cmd(int objd, unsigned int cmd, unsigned long arg,
 609         union ust_args *uargs, void *owner)
 610 {
 611         struct lttng_ust_tracepoint_list *list = objd_private(objd);
 612         struct lttng_ust_tracepoint_iter *tp =
 613                 (struct lttng_ust_tracepoint_iter *) arg;
 614         struct lttng_ust_tracepoint_iter *iter;
 615
 616         switch (cmd) {
 617         case LTTNG_UST_TRACEPOINT_LIST_GET:
 618         {
 619                 iter = lttng_ust_tracepoint_list_get_iter_next(list);
 620                 if (!iter)
 621                         return -LTTNG_UST_ERR_NOENT;
 622                 memcpy(tp, iter, sizeof(*tp));
 623                 return 0;
 624         }
 625         default:
 626                 return -EINVAL;
 627         }
 628 }
 629
 630 static
 631 int lttng_abi_tracepoint_list(void *owner)
 632 {
 633         int list_objd, ret;
 634         struct lttng_ust_tracepoint_list *list;
 635
 636         list_objd = objd_alloc(NULL, &lttng_tracepoint_list_ops, owner, "tp_list");
 637         if (list_objd < 0) {
 638                 ret = list_objd;
 639                 goto objd_error;
 640         }
 641         list = zmalloc(sizeof(*list));
 642         if (!list) {
 643                 ret = -ENOMEM;
 644                 goto alloc_error;
 645         }
 646         objd_set_private(list_objd, list);
 647
 648         /* populate list by walking on all registered probes. */
 649         ret = lttng_probes_get_event_list(list);
 650         if (ret) {
 651                 goto list_error;
 652         }
 653         return list_objd;
 654
 655 list_error:
 656         free(list);
 657 alloc_error:
 658         {
 659                 int err;
 660
 661                 err = lttng_ust_objd_unref(list_objd, 1);
 662                 assert(!err);
 663         }
 664 objd_error:
 665         return ret;
 666 }
 667
 668 static
 669 int lttng_release_tracepoint_list(int objd)
 670 {
 671         struct lttng_ust_tracepoint_list *list = objd_private(objd);
 672
 673         if (list) {
 674                 lttng_probes_prune_event_list(list);
 675                 free(list);
 676                 return 0;
 677         } else {
 678                 return -EINVAL;
 679         }
 680 }
 681
 682 static const struct lttng_ust_objd_ops lttng_tracepoint_list_ops = {
 683         .release = lttng_release_tracepoint_list,
 684         .cmd = lttng_tracepoint_list_cmd,
 685 };
 686
 687 static
 688 long lttng_tracepoint_field_list_cmd(int objd, unsigned int cmd,
 689         unsigned long arg, union ust_args *uargs, void *owner)
 690 {
 691         struct lttng_ust_field_list *list = objd_private(objd);
 692         struct lttng_ust_field_iter *tp = &uargs->field_list.entry;
 693         struct lttng_ust_field_iter *iter;
 694
 695         switch (cmd) {
 696         case LTTNG_UST_TRACEPOINT_FIELD_LIST_GET:
 697         {
 698                 iter = lttng_ust_field_list_get_iter_next(list);
 699                 if (!iter)
 700                         return -LTTNG_UST_ERR_NOENT;
 701                 memcpy(tp, iter, sizeof(*tp));
 702                 return 0;
 703         }
 704         default:
 705                 return -EINVAL;
 706         }
 707 }
 708
 709 static
 710 int lttng_abi_tracepoint_field_list(void *owner)
 711 {
 712         int list_objd, ret;
 713         struct lttng_ust_field_list *list;
 714
 715         list_objd = objd_alloc(NULL, &lttng_tracepoint_field_list_ops, owner,
 716                         "tp_field_list");
 717         if (list_objd < 0) {
 718                 ret = list_objd;
 719                 goto objd_error;
 720         }
 721         list = zmalloc(sizeof(*list));
 722         if (!list) {
 723                 ret = -ENOMEM;
 724                 goto alloc_error;
 725         }
 726         objd_set_private(list_objd, list);
 727
 728         /* populate list by walking on all registered probes. */
 729         ret = lttng_probes_get_field_list(list);
 730         if (ret) {
 731                 goto list_error;
 732         }
 733         return list_objd;
 734
 735 list_error:
 736         free(list);
 737 alloc_error:
 738         {
 739                 int err;
 740
 741                 err = lttng_ust_objd_unref(list_objd, 1);
 742                 assert(!err);
 743         }
 744 objd_error:
 745         return ret;
 746 }
 747
 748 static
 749 int lttng_release_tracepoint_field_list(int objd)
 750 {
 751         struct lttng_ust_field_list *list = objd_private(objd);
 752
 753         if (list) {
 754                 lttng_probes_prune_field_list(list);
 755                 free(list);
 756                 return 0;
 757         } else {
 758                 return -EINVAL;
 759         }
 760 }
 761
 762 static const struct lttng_ust_objd_ops lttng_tracepoint_field_list_ops = {
 763         .release = lttng_release_tracepoint_field_list,
 764         .cmd = lttng_tracepoint_field_list_cmd,
 765 };
 766
 767 static
 768 int lttng_abi_map_stream(int channel_objd, struct lttng_ust_stream *info,
 769                 union ust_args *uargs, void *owner)
 770 {
 771         struct lttng_channel *channel = objd_private(channel_objd);
 772         int ret;
 773
 774         ret = channel_handle_add_stream(channel->handle,
 775                 uargs->stream.shm_fd, uargs->stream.wakeup_fd,
 776                 info->stream_nr, info->len);
 777         if (ret)
 778                 goto error_add_stream;
 779
 780         return 0;
 781
 782 error_add_stream:
 783         return ret;
 784 }
 785
 786 static
 787 int lttng_abi_create_enabler(int channel_objd,
 788                            struct lttng_ust_event *event_param,
 789                            void *owner,
 790                            enum lttng_enabler_type type)
 791 {
 792         struct lttng_channel *channel = objd_private(channel_objd);
 793         struct lttng_enabler *enabler;
 794         int event_objd, ret;
 795
 796         event_param->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 797         event_objd = objd_alloc(NULL, &lttng_enabler_ops, owner, "enabler");
 798         if (event_objd < 0) {
 799                 ret = event_objd;
 800                 goto objd_error;
 801         }
 802         /*
 803          * We tolerate no failure path after event creation. It will stay
 804          * invariant for the rest of the session.
 805          */
 806         enabler = lttng_enabler_create(type, event_param, channel);
 807         if (!enabler) {
 808                 ret = -ENOMEM;
 809                 goto event_error;
 810         }
 811         objd_set_private(event_objd, enabler);
 812         /* The event holds a reference on the channel */
 813         objd_ref(channel_objd);
 814         return event_objd;
 815
 816 event_error:
 817         {
 818                 int err;
 819
 820                 err = lttng_ust_objd_unref(event_objd, 1);
 821                 assert(!err);
 822         }
 823 objd_error:
 824         return ret;
 825 }
 826
 827 /**
 828  *      lttng_channel_cmd - lttng control through object descriptors
 829  *
 830  *      @objd: the object descriptor
 831  *      @cmd: the command
 832  *      @arg: command arg
 833  *      @uargs: UST arguments (internal)
 834  *      @owner: objd owner
 835  *
 836  *      This object descriptor implements lttng commands:
 837  *      LTTNG_UST_STREAM
 838  *              Returns an event stream object descriptor or failure.
 839  *              (typically, one event stream records events from one CPU)
 840  *      LTTNG_UST_EVENT
 841  *              Returns an event object descriptor or failure.
 842  *      LTTNG_UST_CONTEXT
 843  *              Prepend a context field to each event in the channel
 844  *      LTTNG_UST_ENABLE
 845  *              Enable recording for events in this channel (weak enable)
 846  *      LTTNG_UST_DISABLE
 847  *              Disable recording for events in this channel (strong disable)
 848  *
 849  * Channel and event file descriptors also hold a reference on the session.
 850  */
 851 static
 852 long lttng_channel_cmd(int objd, unsigned int cmd, unsigned long arg,
 853         union ust_args *uargs, void *owner)
 854 {
 855         struct lttng_channel *channel = objd_private(objd);
 856
 857         if (cmd != LTTNG_UST_STREAM) {
 858                 /*
 859                  * Check if channel received all streams.
 860                  */
 861                 if (!lttng_is_channel_ready(channel))
 862                         return -EPERM;
 863         }
 864
 865         switch (cmd) {
 866         case LTTNG_UST_STREAM:
 867         {
 868                 struct lttng_ust_stream *stream;
 869
 870                 stream = (struct lttng_ust_stream *) arg;
 871                 /* stream used as output */
 872                 return lttng_abi_map_stream(objd, stream, uargs, owner);
 873         }
 874         case LTTNG_UST_EVENT:
 875         {
 876                 struct lttng_ust_event *event_param =
 877                         (struct lttng_ust_event *) arg;
 878                 if (event_param->name[strlen(event_param->name) - 1] == '*') {
 879                         /* If ends with wildcard, create wildcard. */
 880                         return lttng_abi_create_enabler(objd, event_param,
 881                                         owner, LTTNG_ENABLER_WILDCARD);
 882                 } else {
 883                         return lttng_abi_create_enabler(objd, event_param,
 884                                         owner, LTTNG_ENABLER_EVENT);
 885                 }
 886         }
 887         case LTTNG_UST_CONTEXT:
 888                 return lttng_abi_add_context(objd,
 889                                 (struct lttng_ust_context *) arg,
 890                                 &channel->ctx, channel->session);
 891         case LTTNG_UST_ENABLE:
 892                 return lttng_channel_enable(channel);
 893         case LTTNG_UST_DISABLE:
 894                 return lttng_channel_disable(channel);
 895         case LTTNG_UST_FLUSH_BUFFER:
 896                 return channel->ops->flush_buffer(channel->chan, channel->handle);
 897         default:
 898                 return -EINVAL;
 899         }
 900 }
 901
 902 static
 903 int lttng_channel_release(int objd)
 904 {
 905         struct lttng_channel *channel = objd_private(objd);
 906
 907         if (channel)
 908                 return lttng_ust_objd_unref(channel->session->objd, 0);
 909         return 0;
 910 }
 911
 912 static const struct lttng_ust_objd_ops lttng_channel_ops = {
 913         .release = lttng_channel_release,
 914         .cmd = lttng_channel_cmd,
 915 };
 916
 917 /**
 918  *      lttng_enabler_cmd - lttng control through object descriptors
 919  *
 920  *      @objd: the object descriptor
 921  *      @cmd: the command
 922  *      @arg: command arg
 923  *      @uargs: UST arguments (internal)
 924  *      @owner: objd owner
 925  *
 926  *      This object descriptor implements lttng commands:
 927  *      LTTNG_UST_CONTEXT
 928  *              Prepend a context field to each record of events of this
 929  *              enabler.
 930  *      LTTNG_UST_ENABLE
 931  *              Enable recording for this enabler
 932  *      LTTNG_UST_DISABLE
 933  *              Disable recording for this enabler
 934  *      LTTNG_UST_FILTER
 935  *              Attach a filter to an enabler.
 936  */
 937 static
 938 long lttng_enabler_cmd(int objd, unsigned int cmd, unsigned long arg,
 939         union ust_args *uargs, void *owner)
 940 {
 941         struct lttng_enabler *enabler = objd_private(objd);
 942
 943         switch (cmd) {
 944         case LTTNG_UST_CONTEXT:
 945                 return lttng_enabler_attach_context(enabler,
 946                                 (struct lttng_ust_context *) arg);
 947         case LTTNG_UST_ENABLE:
 948                 return lttng_enabler_enable(enabler);
 949         case LTTNG_UST_DISABLE:
 950                 return lttng_enabler_disable(enabler);
 951         case LTTNG_UST_FILTER:
 952         {
 953                 int ret;
 954
 955                 ret = lttng_enabler_attach_bytecode(enabler,
 956                                 (struct lttng_ust_filter_bytecode_node *) arg);
 957                 if (ret)
 958                         return ret;
 959                 return 0;
 960         }
 961         default:
 962                 return -EINVAL;
 963         }
 964 }
 965
 966 static
 967 int lttng_enabler_release(int objd)
 968 {
 969         struct lttng_enabler *enabler = objd_private(objd);
 970
 971         if (enabler)
 972                 return lttng_ust_objd_unref(enabler->chan->objd, 0);
 973         return 0;
 974 }
 975
 976 static const struct lttng_ust_objd_ops lttng_enabler_ops = {
 977         .release = lttng_enabler_release,
 978         .cmd = lttng_enabler_cmd,
 979 };
 980
 981 void lttng_ust_abi_exit(void)
 982 {
 983         lttng_ust_abi_close_in_progress = 1;
 984         objd_table_destroy();
 985         lttng_ust_abi_close_in_progress = 0;
 986 }