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 #define _LGPL_SOURCE
  41 #include <lttng/ust-abi.h>
  42 #include <lttng/ust-error.h>
  43 #include <urcu/compiler.h>
  44 #include <urcu/list.h>
  45 #include <lttng/ust-events.h>
  46 #include <lttng/ust-version.h>
  47 #include <lttng/tracepoint.h>
  48 #include <ust-fd.h>
  49 #include "tracepoint-internal.h"
  50 #include <usterr-signal-safe.h>
  51 #include <helper.h>
  52 #include "lttng-tracer.h"
  53 #include "../libringbuffer/shm.h"
  54 #include "../libringbuffer/frontend_types.h"
  55
  56 #define OBJ_NAME_LEN    16
  57
  58 static int lttng_ust_abi_close_in_progress;
  59
  60 static
  61 int lttng_abi_tracepoint_list(void *owner);
  62 static
  63 int lttng_abi_tracepoint_field_list(void *owner);
  64
  65 /*
  66  * Object descriptor table. Should be protected from concurrent access
  67  * by the caller.
  68  */
  69
  70 struct lttng_ust_obj {
  71         union {
  72                 struct {
  73                         void *private_data;
  74                         const struct lttng_ust_objd_ops *ops;
  75                         int f_count;
  76                         int owner_ref;  /* has ref from owner */
  77                         void *owner;
  78                         char name[OBJ_NAME_LEN];
  79                 } s;
  80                 int freelist_next;      /* offset freelist. end is -1. */
  81         } u;
  82 };
  83
  84 struct lttng_ust_objd_table {
  85         struct lttng_ust_obj *array;
  86         unsigned int len, allocated_len;
  87         int freelist_head;              /* offset freelist head. end is -1 */
  88 };
  89
  90 static struct lttng_ust_objd_table objd_table = {
  91         .freelist_head = -1,
  92 };
  93
  94 static
  95 int objd_alloc(void *private_data, const struct lttng_ust_objd_ops *ops,
  96                 void *owner, const char *name)
  97 {
  98         struct lttng_ust_obj *obj;
  99
 100         if (objd_table.freelist_head != -1) {
 101                 obj = &objd_table.array[objd_table.freelist_head];
 102                 objd_table.freelist_head = obj->u.freelist_next;
 103                 goto end;
 104         }
 105
 106         if (objd_table.len >= objd_table.allocated_len) {
 107                 unsigned int new_allocated_len, old_allocated_len;
 108                 struct lttng_ust_obj *new_table, *old_table;
 109
 110                 old_allocated_len = objd_table.allocated_len;
 111                 old_table = objd_table.array;
 112                 if (!old_allocated_len)
 113                         new_allocated_len = 1;
 114                 else
 115                         new_allocated_len = old_allocated_len << 1;
 116                 new_table = zmalloc(sizeof(struct lttng_ust_obj) * new_allocated_len);
 117                 if (!new_table)
 118                         return -ENOMEM;
 119                 memcpy(new_table, old_table,
 120                        sizeof(struct lttng_ust_obj) * old_allocated_len);
 121                 free(old_table);
 122                 objd_table.array = new_table;
 123                 objd_table.allocated_len = new_allocated_len;
 124         }
 125         obj = &objd_table.array[objd_table.len];
 126         objd_table.len++;
 127 end:
 128         obj->u.s.private_data = private_data;
 129         obj->u.s.ops = ops;
 130         obj->u.s.f_count = 2;   /* count == 1 : object is allocated */
 131                                 /* count == 2 : allocated + hold ref */
 132         obj->u.s.owner_ref = 1; /* One owner reference */
 133         obj->u.s.owner = owner;
 134         strncpy(obj->u.s.name, name, OBJ_NAME_LEN);
 135         obj->u.s.name[OBJ_NAME_LEN - 1] = '\0';
 136         return obj - objd_table.array;
 137 }
 138
 139 static
 140 struct lttng_ust_obj *_objd_get(int id)
 141 {
 142         if (id >= objd_table.len)
 143                 return NULL;
 144         if (!objd_table.array[id].u.s.f_count)
 145                 return NULL;
 146         return &objd_table.array[id];
 147 }
 148
 149 static
 150 void *objd_private(int id)
 151 {
 152         struct lttng_ust_obj *obj = _objd_get(id);
 153         assert(obj);
 154         return obj->u.s.private_data;
 155 }
 156
 157 static
 158 void objd_set_private(int id, void *private_data)
 159 {
 160         struct lttng_ust_obj *obj = _objd_get(id);
 161         assert(obj);
 162         obj->u.s.private_data = private_data;
 163 }
 164
 165 const struct lttng_ust_objd_ops *objd_ops(int id)
 166 {
 167         struct lttng_ust_obj *obj = _objd_get(id);
 168
 169         if (!obj)
 170                 return NULL;
 171         return obj->u.s.ops;
 172 }
 173
 174 static
 175 void objd_free(int id)
 176 {
 177         struct lttng_ust_obj *obj = _objd_get(id);
 178
 179         assert(obj);
 180         obj->u.freelist_next = objd_table.freelist_head;
 181         objd_table.freelist_head = obj - objd_table.array;
 182         assert(obj->u.s.f_count == 1);
 183         obj->u.s.f_count = 0;   /* deallocated */
 184 }
 185
 186 static
 187 void objd_ref(int id)
 188 {
 189         struct lttng_ust_obj *obj = _objd_get(id);
 190         assert(obj != NULL);
 191         obj->u.s.f_count++;
 192 }
 193
 194 int lttng_ust_objd_unref(int id, int is_owner)
 195 {
 196         struct lttng_ust_obj *obj = _objd_get(id);
 197
 198         if (!obj)
 199                 return -EINVAL;
 200         if (obj->u.s.f_count == 1) {
 201                 ERR("Reference counting error\n");
 202                 return -EINVAL;
 203         }
 204         if (is_owner) {
 205                 if (!obj->u.s.owner_ref) {
 206                         ERR("Error decrementing owner reference");
 207                         return -EINVAL;
 208                 }
 209                 obj->u.s.owner_ref--;
 210         }
 211         if ((--obj->u.s.f_count) == 1) {
 212                 const struct lttng_ust_objd_ops *ops = objd_ops(id);
 213
 214                 if (ops->release)
 215                         ops->release(id);
 216                 objd_free(id);
 217         }
 218         return 0;
 219 }
 220
 221 static
 222 void objd_table_destroy(void)
 223 {
 224         int i;
 225
 226         for (i = 0; i < objd_table.allocated_len; i++) {
 227                 struct lttng_ust_obj *obj;
 228
 229                 obj = _objd_get(i);
 230                 if (!obj)
 231                         continue;
 232                 if (!obj->u.s.owner_ref)
 233                         continue;       /* only unref owner ref. */
 234                 (void) lttng_ust_objd_unref(i, 1);
 235         }
 236         free(objd_table.array);
 237         objd_table.array = NULL;
 238         objd_table.len = 0;
 239         objd_table.allocated_len = 0;
 240         objd_table.freelist_head = -1;
 241 }
 242
 243 const char *lttng_ust_obj_get_name(int id)
 244 {
 245         struct lttng_ust_obj *obj = _objd_get(id);
 246
 247         if (!obj)
 248                 return NULL;
 249         return obj->u.s.name;
 250 }
 251
 252 void lttng_ust_objd_table_owner_cleanup(void *owner)
 253 {
 254         int i;
 255
 256         for (i = 0; i < objd_table.allocated_len; i++) {
 257                 struct lttng_ust_obj *obj;
 258
 259                 obj = _objd_get(i);
 260                 if (!obj)
 261                         continue;
 262                 if (!obj->u.s.owner)
 263                         continue;       /* skip root handles */
 264                 if (!obj->u.s.owner_ref)
 265                         continue;       /* only unref owner ref. */
 266                 if (obj->u.s.owner == owner)
 267                         (void) lttng_ust_objd_unref(i, 1);
 268         }
 269 }
 270
 271 /*
 272  * This is LTTng's own personal way to create an ABI for sessiond.
 273  * We send commands over a socket.
 274  */
 275
 276 static const struct lttng_ust_objd_ops lttng_ops;
 277 static const struct lttng_ust_objd_ops lttng_session_ops;
 278 static const struct lttng_ust_objd_ops lttng_channel_ops;
 279 static const struct lttng_ust_objd_ops lttng_enabler_ops;
 280 static const struct lttng_ust_objd_ops lttng_tracepoint_list_ops;
 281 static const struct lttng_ust_objd_ops lttng_tracepoint_field_list_ops;
 282
 283 int lttng_abi_create_root_handle(void)
 284 {
 285         int root_handle;
 286
 287         /* root handles have NULL owners */
 288         root_handle = objd_alloc(NULL, &lttng_ops, NULL, "root");
 289         return root_handle;
 290 }
 291
 292 static
 293 int lttng_is_channel_ready(struct lttng_channel *lttng_chan)
 294 {
 295         struct channel *chan;
 296         unsigned int nr_streams, exp_streams;
 297
 298         chan = lttng_chan->chan;
 299         nr_streams = channel_handle_get_nr_streams(lttng_chan->handle);
 300         exp_streams = chan->nr_streams;
 301         return nr_streams == exp_streams;
 302 }
 303
 304 static
 305 int lttng_abi_create_session(void *owner)
 306 {
 307         struct lttng_session *session;
 308         int session_objd, ret;
 309
 310         session = lttng_session_create();
 311         if (!session)
 312                 return -ENOMEM;
 313         session_objd = objd_alloc(session, &lttng_session_ops, owner, "session");
 314         if (session_objd < 0) {
 315                 ret = session_objd;
 316                 goto objd_error;
 317         }
 318         session->objd = session_objd;
 319         session->owner = owner;
 320         return session_objd;
 321
 322 objd_error:
 323         lttng_session_destroy(session);
 324         return ret;
 325 }
 326
 327 static
 328 long lttng_abi_tracer_version(int objd,
 329         struct lttng_ust_tracer_version *v)
 330 {
 331         v->major = LTTNG_UST_MAJOR_VERSION;
 332         v->minor = LTTNG_UST_MINOR_VERSION;
 333         v->patchlevel = LTTNG_UST_PATCHLEVEL_VERSION;
 334         return 0;
 335 }
 336
 337 static
 338 long lttng_abi_add_context(int objd,
 339         struct lttng_ust_context *context_param,
 340         union ust_args *uargs,
 341         struct lttng_ctx **ctx, struct lttng_session *session)
 342 {
 343         return lttng_attach_context(context_param, uargs, ctx, session);
 344 }
 345
 346 /**
 347  *      lttng_cmd - lttng control through socket commands
 348  *
 349  *      @objd: the object descriptor
 350  *      @cmd: the command
 351  *      @arg: command arg
 352  *      @uargs: UST arguments (internal)
 353  *      @owner: objd owner
 354  *
 355  *      This descriptor implements lttng commands:
 356  *      LTTNG_UST_SESSION
 357  *              Returns a LTTng trace session object descriptor
 358  *      LTTNG_UST_TRACER_VERSION
 359  *              Returns the LTTng kernel tracer version
 360  *      LTTNG_UST_TRACEPOINT_LIST
 361  *              Returns a file descriptor listing available tracepoints
 362  *      LTTNG_UST_TRACEPOINT_FIELD_LIST
 363  *              Returns a file descriptor listing available tracepoint fields
 364  *      LTTNG_UST_WAIT_QUIESCENT
 365  *              Returns after all previously running probes have completed
 366  *
 367  * The returned session will be deleted when its file descriptor is closed.
 368  */
 369 static
 370 long lttng_cmd(int objd, unsigned int cmd, unsigned long arg,
 371         union ust_args *uargs, void *owner)
 372 {
 373         switch (cmd) {
 374         case LTTNG_UST_SESSION:
 375                 return lttng_abi_create_session(owner);
 376         case LTTNG_UST_TRACER_VERSION:
 377                 return lttng_abi_tracer_version(objd,
 378                                 (struct lttng_ust_tracer_version *) arg);
 379         case LTTNG_UST_TRACEPOINT_LIST:
 380                 return lttng_abi_tracepoint_list(owner);
 381         case LTTNG_UST_TRACEPOINT_FIELD_LIST:
 382                 return lttng_abi_tracepoint_field_list(owner);
 383         case LTTNG_UST_WAIT_QUIESCENT:
 384                 synchronize_trace();
 385                 return 0;
 386         default:
 387                 return -EINVAL;
 388         }
 389 }
 390
 391 static const struct lttng_ust_objd_ops lttng_ops = {
 392         .cmd = lttng_cmd,
 393 };
 394
 395 int lttng_abi_map_channel(int session_objd,
 396                 struct lttng_ust_channel *ust_chan,
 397                 union ust_args *uargs,
 398                 void *owner)
 399 {
 400         struct lttng_session *session = objd_private(session_objd);
 401         const char *transport_name;
 402         const struct lttng_transport *transport;
 403         const char *chan_name;
 404         int chan_objd;
 405         struct lttng_ust_shm_handle *channel_handle;
 406         struct lttng_channel *lttng_chan;
 407         struct channel *chan;
 408         struct lttng_ust_lib_ring_buffer_config *config;
 409         void *chan_data;
 410         int wakeup_fd;
 411         uint64_t len;
 412         int ret;
 413         enum lttng_ust_chan_type type;
 414
 415         chan_data = uargs->channel.chan_data;
 416         wakeup_fd = uargs->channel.wakeup_fd;
 417         len = ust_chan->len;
 418         type = ust_chan->type;
 419
 420         switch (type) {
 421         case LTTNG_UST_CHAN_PER_CPU:
 422                 break;
 423         default:
 424                 ret = -EINVAL;
 425                 goto invalid;
 426         }
 427
 428         if (session->been_active) {
 429                 ret = -EBUSY;
 430                 goto active;    /* Refuse to add channel to active session */
 431         }
 432
 433         channel_handle = channel_handle_create(chan_data, len, wakeup_fd);
 434         if (!channel_handle) {
 435                 ret = -EINVAL;
 436                 goto handle_error;
 437         }
 438
 439         chan = shmp(channel_handle, channel_handle->chan);
 440         assert(chan);
 441         chan->handle = channel_handle;
 442         config = &chan->backend.config;
 443         lttng_chan = channel_get_private(chan);
 444         if (!lttng_chan) {
 445                 ret = -EINVAL;
 446                 goto alloc_error;
 447         }
 448
 449         /* Lookup transport name */
 450         switch (type) {
 451         case LTTNG_UST_CHAN_PER_CPU:
 452                 if (config->output == RING_BUFFER_MMAP) {
 453                         if (config->mode == RING_BUFFER_OVERWRITE) {
 454                                 if (config->wakeup == RING_BUFFER_WAKEUP_BY_WRITER) {
 455                                         transport_name = "relay-overwrite-mmap";
 456                                 } else {
 457                                         transport_name = "relay-overwrite-rt-mmap";
 458                                 }
 459                         } else {
 460                                 if (config->wakeup == RING_BUFFER_WAKEUP_BY_WRITER) {
 461                                         transport_name = "relay-discard-mmap";
 462                                 } else {
 463                                         transport_name = "relay-discard-rt-mmap";
 464                                 }
 465                         }
 466                 } else {
 467                         ret = -EINVAL;
 468                         goto notransport;
 469                 }
 470                 chan_name = "channel";
 471                 break;
 472         default:
 473                 ret = -EINVAL;
 474                 goto notransport;
 475         }
 476         transport = lttng_transport_find(transport_name);
 477         if (!transport) {
 478                 DBG("LTTng transport %s not found\n",
 479                        transport_name);
 480                 ret = -EINVAL;
 481                 goto notransport;
 482         }
 483
 484         chan_objd = objd_alloc(NULL, &lttng_channel_ops, owner, chan_name);
 485         if (chan_objd < 0) {
 486                 ret = chan_objd;
 487                 goto objd_error;
 488         }
 489
 490         /* Initialize our lttng chan */
 491         lttng_chan->chan = chan;
 492         lttng_chan->tstate = 1;
 493         lttng_chan->enabled = 1;
 494         lttng_chan->ctx = NULL;
 495         lttng_chan->session = session;
 496         lttng_chan->ops = &transport->ops;
 497         memcpy(&lttng_chan->chan->backend.config,
 498                 transport->client_config,
 499                 sizeof(lttng_chan->chan->backend.config));
 500         cds_list_add(&lttng_chan->node, &session->chan_head);
 501         lttng_chan->header_type = 0;
 502         lttng_chan->handle = channel_handle;
 503         lttng_chan->type = type;
 504
 505         /*
 506          * We tolerate no failure path after channel creation. It will stay
 507          * invariant for the rest of the session.
 508          */
 509         objd_set_private(chan_objd, lttng_chan);
 510         lttng_chan->objd = chan_objd;
 511         /* The channel created holds a reference on the session */
 512         objd_ref(session_objd);
 513         return chan_objd;
 514
 515         /* error path after channel was created */
 516 objd_error:
 517 notransport:
 518 alloc_error:
 519         channel_destroy(chan, channel_handle, 0);
 520         return ret;
 521
 522         /*
 523          * error path before channel creation (owning chan_data and
 524          * wakeup_fd).
 525          */
 526 handle_error:
 527 active:
 528 invalid:
 529         {
 530                 int close_ret;
 531
 532                 lttng_ust_lock_fd_tracker();
 533                 close_ret = close(wakeup_fd);
 534                 lttng_ust_unlock_fd_tracker();
 535                 if (close_ret) {
 536                         PERROR("close");
 537                 }
 538         }
 539         free(chan_data);
 540         return ret;
 541 }
 542
 543 /**
 544  *      lttng_session_cmd - lttng session object command
 545  *
 546  *      @obj: the object
 547  *      @cmd: the command
 548  *      @arg: command arg
 549  *      @uargs: UST arguments (internal)
 550  *      @owner: objd owner
 551  *
 552  *      This descriptor implements lttng commands:
 553  *      LTTNG_UST_CHANNEL
 554  *              Returns a LTTng channel object descriptor
 555  *      LTTNG_UST_ENABLE
 556  *              Enables tracing for a session (weak enable)
 557  *      LTTNG_UST_DISABLE
 558  *              Disables tracing for a session (strong disable)
 559  *
 560  * The returned channel will be deleted when its file descriptor is closed.
 561  */
 562 static
 563 long lttng_session_cmd(int objd, unsigned int cmd, unsigned long arg,
 564         union ust_args *uargs, void *owner)
 565 {
 566         struct lttng_session *session = objd_private(objd);
 567
 568         switch (cmd) {
 569         case LTTNG_UST_CHANNEL:
 570                 return lttng_abi_map_channel(objd,
 571                                 (struct lttng_ust_channel *) arg,
 572                                 uargs, owner);
 573         case LTTNG_UST_SESSION_START:
 574         case LTTNG_UST_ENABLE:
 575                 return lttng_session_enable(session);
 576         case LTTNG_UST_SESSION_STOP:
 577         case LTTNG_UST_DISABLE:
 578                 return lttng_session_disable(session);
 579         case LTTNG_UST_SESSION_STATEDUMP:
 580                 return lttng_session_statedump(session);
 581         default:
 582                 return -EINVAL;
 583         }
 584 }
 585
 586 /*
 587  * Called when the last file reference is dropped.
 588  *
 589  * Big fat note: channels and events are invariant for the whole session after
 590  * their creation. So this session destruction also destroys all channel and
 591  * event structures specific to this session (they are not destroyed when their
 592  * individual file is released).
 593  */
 594 static
 595 int lttng_release_session(int objd)
 596 {
 597         struct lttng_session *session = objd_private(objd);
 598
 599         if (session) {
 600                 lttng_session_destroy(session);
 601                 return 0;
 602         } else {
 603                 return -EINVAL;
 604         }
 605 }
 606
 607 static const struct lttng_ust_objd_ops lttng_session_ops = {
 608         .release = lttng_release_session,
 609         .cmd = lttng_session_cmd,
 610 };
 611
 612 static
 613 long lttng_tracepoint_list_cmd(int objd, unsigned int cmd, unsigned long arg,
 614         union ust_args *uargs, void *owner)
 615 {
 616         struct lttng_ust_tracepoint_list *list = objd_private(objd);
 617         struct lttng_ust_tracepoint_iter *tp =
 618                 (struct lttng_ust_tracepoint_iter *) arg;
 619         struct lttng_ust_tracepoint_iter *iter;
 620
 621         switch (cmd) {
 622         case LTTNG_UST_TRACEPOINT_LIST_GET:
 623         {
 624                 iter = lttng_ust_tracepoint_list_get_iter_next(list);
 625                 if (!iter)
 626                         return -LTTNG_UST_ERR_NOENT;
 627                 memcpy(tp, iter, sizeof(*tp));
 628                 return 0;
 629         }
 630         default:
 631                 return -EINVAL;
 632         }
 633 }
 634
 635 static
 636 int lttng_abi_tracepoint_list(void *owner)
 637 {
 638         int list_objd, ret;
 639         struct lttng_ust_tracepoint_list *list;
 640
 641         list_objd = objd_alloc(NULL, &lttng_tracepoint_list_ops, owner, "tp_list");
 642         if (list_objd < 0) {
 643                 ret = list_objd;
 644                 goto objd_error;
 645         }
 646         list = zmalloc(sizeof(*list));
 647         if (!list) {
 648                 ret = -ENOMEM;
 649                 goto alloc_error;
 650         }
 651         objd_set_private(list_objd, list);
 652
 653         /* populate list by walking on all registered probes. */
 654         ret = lttng_probes_get_event_list(list);
 655         if (ret) {
 656                 goto list_error;
 657         }
 658         return list_objd;
 659
 660 list_error:
 661         free(list);
 662 alloc_error:
 663         {
 664                 int err;
 665
 666                 err = lttng_ust_objd_unref(list_objd, 1);
 667                 assert(!err);
 668         }
 669 objd_error:
 670         return ret;
 671 }
 672
 673 static
 674 int lttng_release_tracepoint_list(int objd)
 675 {
 676         struct lttng_ust_tracepoint_list *list = objd_private(objd);
 677
 678         if (list) {
 679                 lttng_probes_prune_event_list(list);
 680                 free(list);
 681                 return 0;
 682         } else {
 683                 return -EINVAL;
 684         }
 685 }
 686
 687 static const struct lttng_ust_objd_ops lttng_tracepoint_list_ops = {
 688         .release = lttng_release_tracepoint_list,
 689         .cmd = lttng_tracepoint_list_cmd,
 690 };
 691
 692 static
 693 long lttng_tracepoint_field_list_cmd(int objd, unsigned int cmd,
 694         unsigned long arg, union ust_args *uargs, void *owner)
 695 {
 696         struct lttng_ust_field_list *list = objd_private(objd);
 697         struct lttng_ust_field_iter *tp = &uargs->field_list.entry;
 698         struct lttng_ust_field_iter *iter;
 699
 700         switch (cmd) {
 701         case LTTNG_UST_TRACEPOINT_FIELD_LIST_GET:
 702         {
 703                 iter = lttng_ust_field_list_get_iter_next(list);
 704                 if (!iter)
 705                         return -LTTNG_UST_ERR_NOENT;
 706                 memcpy(tp, iter, sizeof(*tp));
 707                 return 0;
 708         }
 709         default:
 710                 return -EINVAL;
 711         }
 712 }
 713
 714 static
 715 int lttng_abi_tracepoint_field_list(void *owner)
 716 {
 717         int list_objd, ret;
 718         struct lttng_ust_field_list *list;
 719
 720         list_objd = objd_alloc(NULL, &lttng_tracepoint_field_list_ops, owner,
 721                         "tp_field_list");
 722         if (list_objd < 0) {
 723                 ret = list_objd;
 724                 goto objd_error;
 725         }
 726         list = zmalloc(sizeof(*list));
 727         if (!list) {
 728                 ret = -ENOMEM;
 729                 goto alloc_error;
 730         }
 731         objd_set_private(list_objd, list);
 732
 733         /* populate list by walking on all registered probes. */
 734         ret = lttng_probes_get_field_list(list);
 735         if (ret) {
 736                 goto list_error;
 737         }
 738         return list_objd;
 739
 740 list_error:
 741         free(list);
 742 alloc_error:
 743         {
 744                 int err;
 745
 746                 err = lttng_ust_objd_unref(list_objd, 1);
 747                 assert(!err);
 748         }
 749 objd_error:
 750         return ret;
 751 }
 752
 753 static
 754 int lttng_release_tracepoint_field_list(int objd)
 755 {
 756         struct lttng_ust_field_list *list = objd_private(objd);
 757
 758         if (list) {
 759                 lttng_probes_prune_field_list(list);
 760                 free(list);
 761                 return 0;
 762         } else {
 763                 return -EINVAL;
 764         }
 765 }
 766
 767 static const struct lttng_ust_objd_ops lttng_tracepoint_field_list_ops = {
 768         .release = lttng_release_tracepoint_field_list,
 769         .cmd = lttng_tracepoint_field_list_cmd,
 770 };
 771
 772 static
 773 int lttng_abi_map_stream(int channel_objd, struct lttng_ust_stream *info,
 774                 union ust_args *uargs, void *owner)
 775 {
 776         struct lttng_channel *channel = objd_private(channel_objd);
 777         int ret;
 778
 779         ret = channel_handle_add_stream(channel->handle,
 780                 uargs->stream.shm_fd, uargs->stream.wakeup_fd,
 781                 info->stream_nr, info->len);
 782         if (ret)
 783                 goto error_add_stream;
 784
 785         return 0;
 786
 787 error_add_stream:
 788         return ret;
 789 }
 790
 791 static
 792 int lttng_abi_create_enabler(int channel_objd,
 793                            struct lttng_ust_event *event_param,
 794                            void *owner,
 795                            enum lttng_enabler_type type)
 796 {
 797         struct lttng_channel *channel = objd_private(channel_objd);
 798         struct lttng_enabler *enabler;
 799         int event_objd, ret;
 800
 801         event_param->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 802         event_objd = objd_alloc(NULL, &lttng_enabler_ops, owner, "enabler");
 803         if (event_objd < 0) {
 804                 ret = event_objd;
 805                 goto objd_error;
 806         }
 807         /*
 808          * We tolerate no failure path after event creation. It will stay
 809          * invariant for the rest of the session.
 810          */
 811         enabler = lttng_enabler_create(type, event_param, channel);
 812         if (!enabler) {
 813                 ret = -ENOMEM;
 814                 goto event_error;
 815         }
 816         objd_set_private(event_objd, enabler);
 817         /* The event holds a reference on the channel */
 818         objd_ref(channel_objd);
 819         return event_objd;
 820
 821 event_error:
 822         {
 823                 int err;
 824
 825                 err = lttng_ust_objd_unref(event_objd, 1);
 826                 assert(!err);
 827         }
 828 objd_error:
 829         return ret;
 830 }
 831
 832 /**
 833  *      lttng_channel_cmd - lttng control through object descriptors
 834  *
 835  *      @objd: the object descriptor
 836  *      @cmd: the command
 837  *      @arg: command arg
 838  *      @uargs: UST arguments (internal)
 839  *      @owner: objd owner
 840  *
 841  *      This object descriptor implements lttng commands:
 842  *      LTTNG_UST_STREAM
 843  *              Returns an event stream object descriptor or failure.
 844  *              (typically, one event stream records events from one CPU)
 845  *      LTTNG_UST_EVENT
 846  *              Returns an event object descriptor or failure.
 847  *      LTTNG_UST_CONTEXT
 848  *              Prepend a context field to each event in the channel
 849  *      LTTNG_UST_ENABLE
 850  *              Enable recording for events in this channel (weak enable)
 851  *      LTTNG_UST_DISABLE
 852  *              Disable recording for events in this channel (strong disable)
 853  *
 854  * Channel and event file descriptors also hold a reference on the session.
 855  */
 856 static
 857 long lttng_channel_cmd(int objd, unsigned int cmd, unsigned long arg,
 858         union ust_args *uargs, void *owner)
 859 {
 860         struct lttng_channel *channel = objd_private(objd);
 861
 862         if (cmd != LTTNG_UST_STREAM) {
 863                 /*
 864                  * Check if channel received all streams.
 865                  */
 866                 if (!lttng_is_channel_ready(channel))
 867                         return -EPERM;
 868         }
 869
 870         switch (cmd) {
 871         case LTTNG_UST_STREAM:
 872         {
 873                 struct lttng_ust_stream *stream;
 874
 875                 stream = (struct lttng_ust_stream *) arg;
 876                 /* stream used as output */
 877                 return lttng_abi_map_stream(objd, stream, uargs, owner);
 878         }
 879         case LTTNG_UST_EVENT:
 880         {
 881                 struct lttng_ust_event *event_param =
 882                         (struct lttng_ust_event *) arg;
 883                 if (event_param->name[strlen(event_param->name) - 1] == '*') {
 884                         /* If ends with wildcard, create wildcard. */
 885                         return lttng_abi_create_enabler(objd, event_param,
 886                                         owner, LTTNG_ENABLER_WILDCARD);
 887                 } else {
 888                         return lttng_abi_create_enabler(objd, event_param,
 889                                         owner, LTTNG_ENABLER_EVENT);
 890                 }
 891         }
 892         case LTTNG_UST_CONTEXT:
 893                 return lttng_abi_add_context(objd,
 894                                 (struct lttng_ust_context *) arg, uargs,
 895                                 &channel->ctx, channel->session);
 896         case LTTNG_UST_ENABLE:
 897                 return lttng_channel_enable(channel);
 898         case LTTNG_UST_DISABLE:
 899                 return lttng_channel_disable(channel);
 900         case LTTNG_UST_FLUSH_BUFFER:
 901                 return channel->ops->flush_buffer(channel->chan, channel->handle);
 902         default:
 903                 return -EINVAL;
 904         }
 905 }
 906
 907 static
 908 int lttng_channel_release(int objd)
 909 {
 910         struct lttng_channel *channel = objd_private(objd);
 911
 912         if (channel)
 913                 return lttng_ust_objd_unref(channel->session->objd, 0);
 914         return 0;
 915 }
 916
 917 static const struct lttng_ust_objd_ops lttng_channel_ops = {
 918         .release = lttng_channel_release,
 919         .cmd = lttng_channel_cmd,
 920 };
 921
 922 /**
 923  *      lttng_enabler_cmd - lttng control through object descriptors
 924  *
 925  *      @objd: the object descriptor
 926  *      @cmd: the command
 927  *      @arg: command arg
 928  *      @uargs: UST arguments (internal)
 929  *      @owner: objd owner
 930  *
 931  *      This object descriptor implements lttng commands:
 932  *      LTTNG_UST_CONTEXT
 933  *              Prepend a context field to each record of events of this
 934  *              enabler.
 935  *      LTTNG_UST_ENABLE
 936  *              Enable recording for this enabler
 937  *      LTTNG_UST_DISABLE
 938  *              Disable recording for this enabler
 939  *      LTTNG_UST_FILTER
 940  *              Attach a filter to an enabler.
 941  *      LTTNG_UST_EXCLUSION
 942  *              Attach exclusions to an enabler.
 943  */
 944 static
 945 long lttng_enabler_cmd(int objd, unsigned int cmd, unsigned long arg,
 946         union ust_args *uargs, void *owner)
 947 {
 948         struct lttng_enabler *enabler = objd_private(objd);
 949
 950         switch (cmd) {
 951         case LTTNG_UST_CONTEXT:
 952                 return lttng_enabler_attach_context(enabler,
 953                                 (struct lttng_ust_context *) arg);
 954         case LTTNG_UST_ENABLE:
 955                 return lttng_enabler_enable(enabler);
 956         case LTTNG_UST_DISABLE:
 957                 return lttng_enabler_disable(enabler);
 958         case LTTNG_UST_FILTER:
 959         {
 960                 int ret;
 961
 962                 ret = lttng_enabler_attach_bytecode(enabler,
 963                                 (struct lttng_ust_filter_bytecode_node *) arg);
 964                 if (ret)
 965                         return ret;
 966                 return 0;
 967         }
 968         case LTTNG_UST_EXCLUSION:
 969         {
 970                 return lttng_enabler_attach_exclusion(enabler,
 971                                 (struct lttng_ust_excluder_node *) arg);
 972         }
 973         default:
 974                 return -EINVAL;
 975         }
 976 }
 977
 978 static
 979 int lttng_enabler_release(int objd)
 980 {
 981         struct lttng_enabler *enabler = objd_private(objd);
 982
 983         if (enabler)
 984                 return lttng_ust_objd_unref(enabler->chan->objd, 0);
 985         return 0;
 986 }
 987
 988 static const struct lttng_ust_objd_ops lttng_enabler_ops = {
 989         .release = lttng_enabler_release,
 990         .cmd = lttng_enabler_cmd,
 991 };
 992
 993 void lttng_ust_abi_exit(void)
 994 {
 995         lttng_ust_abi_close_in_progress = 1;
 996         ust_lock_nocheck();
 997         objd_table_destroy();
 998         ust_unlock();
 999         lttng_ust_abi_close_in_progress = 0;
1000 }