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 "string-utils.h"
  54 #include "../libringbuffer/shm.h"
  55 #include "../libringbuffer/frontend_types.h"
  56
  57 #define OBJ_NAME_LEN    16
  58
  59 static int lttng_ust_abi_close_in_progress;
  60
  61 static
  62 int lttng_abi_tracepoint_list(void *owner);
  63 static
  64 int lttng_abi_tracepoint_field_list(void *owner);
  65
  66 /*
  67  * Object descriptor table. Should be protected from concurrent access
  68  * by the caller.
  69  */
  70
  71 struct lttng_ust_obj {
  72         union {
  73                 struct {
  74                         void *private_data;
  75                         const struct lttng_ust_objd_ops *ops;
  76                         int f_count;
  77                         int owner_ref;  /* has ref from owner */
  78                         void *owner;
  79                         char name[OBJ_NAME_LEN];
  80                 } s;
  81                 int freelist_next;      /* offset freelist. end is -1. */
  82         } u;
  83 };
  84
  85 struct lttng_ust_objd_table {
  86         struct lttng_ust_obj *array;
  87         unsigned int len, allocated_len;
  88         int freelist_head;              /* offset freelist head. end is -1 */
  89 };
  90
  91 static struct lttng_ust_objd_table objd_table = {
  92         .freelist_head = -1,
  93 };
  94
  95 static
  96 int objd_alloc(void *private_data, const struct lttng_ust_objd_ops *ops,
  97                 void *owner, const char *name)
  98 {
  99         struct lttng_ust_obj *obj;
 100
 101         if (objd_table.freelist_head != -1) {
 102                 obj = &objd_table.array[objd_table.freelist_head];
 103                 objd_table.freelist_head = obj->u.freelist_next;
 104                 goto end;
 105         }
 106
 107         if (objd_table.len >= objd_table.allocated_len) {
 108                 unsigned int new_allocated_len, old_allocated_len;
 109                 struct lttng_ust_obj *new_table, *old_table;
 110
 111                 old_allocated_len = objd_table.allocated_len;
 112                 old_table = objd_table.array;
 113                 if (!old_allocated_len)
 114                         new_allocated_len = 1;
 115                 else
 116                         new_allocated_len = old_allocated_len << 1;
 117                 new_table = zmalloc(sizeof(struct lttng_ust_obj) * new_allocated_len);
 118                 if (!new_table)
 119                         return -ENOMEM;
 120                 memcpy(new_table, old_table,
 121                        sizeof(struct lttng_ust_obj) * old_allocated_len);
 122                 free(old_table);
 123                 objd_table.array = new_table;
 124                 objd_table.allocated_len = new_allocated_len;
 125         }
 126         obj = &objd_table.array[objd_table.len];
 127         objd_table.len++;
 128 end:
 129         obj->u.s.private_data = private_data;
 130         obj->u.s.ops = ops;
 131         obj->u.s.f_count = 2;   /* count == 1 : object is allocated */
 132                                 /* count == 2 : allocated + hold ref */
 133         obj->u.s.owner_ref = 1; /* One owner reference */
 134         obj->u.s.owner = owner;
 135         strncpy(obj->u.s.name, name, OBJ_NAME_LEN);
 136         obj->u.s.name[OBJ_NAME_LEN - 1] = '\0';
 137         return obj - objd_table.array;
 138 }
 139
 140 static
 141 struct lttng_ust_obj *_objd_get(int id)
 142 {
 143         if (id >= objd_table.len)
 144                 return NULL;
 145         if (!objd_table.array[id].u.s.f_count)
 146                 return NULL;
 147         return &objd_table.array[id];
 148 }
 149
 150 static
 151 void *objd_private(int id)
 152 {
 153         struct lttng_ust_obj *obj = _objd_get(id);
 154         assert(obj);
 155         return obj->u.s.private_data;
 156 }
 157
 158 static
 159 void objd_set_private(int id, void *private_data)
 160 {
 161         struct lttng_ust_obj *obj = _objd_get(id);
 162         assert(obj);
 163         obj->u.s.private_data = private_data;
 164 }
 165
 166 const struct lttng_ust_objd_ops *objd_ops(int id)
 167 {
 168         struct lttng_ust_obj *obj = _objd_get(id);
 169
 170         if (!obj)
 171                 return NULL;
 172         return obj->u.s.ops;
 173 }
 174
 175 static
 176 void objd_free(int id)
 177 {
 178         struct lttng_ust_obj *obj = _objd_get(id);
 179
 180         assert(obj);
 181         obj->u.freelist_next = objd_table.freelist_head;
 182         objd_table.freelist_head = obj - objd_table.array;
 183         assert(obj->u.s.f_count == 1);
 184         obj->u.s.f_count = 0;   /* deallocated */
 185 }
 186
 187 static
 188 void objd_ref(int id)
 189 {
 190         struct lttng_ust_obj *obj = _objd_get(id);
 191         assert(obj != NULL);
 192         obj->u.s.f_count++;
 193 }
 194
 195 int lttng_ust_objd_unref(int id, int is_owner)
 196 {
 197         struct lttng_ust_obj *obj = _objd_get(id);
 198
 199         if (!obj)
 200                 return -EINVAL;
 201         if (obj->u.s.f_count == 1) {
 202                 ERR("Reference counting error\n");
 203                 return -EINVAL;
 204         }
 205         if (is_owner) {
 206                 if (!obj->u.s.owner_ref) {
 207                         ERR("Error decrementing owner reference");
 208                         return -EINVAL;
 209                 }
 210                 obj->u.s.owner_ref--;
 211         }
 212         if ((--obj->u.s.f_count) == 1) {
 213                 const struct lttng_ust_objd_ops *ops = objd_ops(id);
 214
 215                 if (ops->release)
 216                         ops->release(id);
 217                 objd_free(id);
 218         }
 219         return 0;
 220 }
 221
 222 static
 223 void objd_table_destroy(void)
 224 {
 225         int i;
 226
 227         for (i = 0; i < objd_table.allocated_len; i++) {
 228                 struct lttng_ust_obj *obj;
 229
 230                 obj = _objd_get(i);
 231                 if (!obj)
 232                         continue;
 233                 if (!obj->u.s.owner_ref)
 234                         continue;       /* only unref owner ref. */
 235                 (void) lttng_ust_objd_unref(i, 1);
 236         }
 237         free(objd_table.array);
 238         objd_table.array = NULL;
 239         objd_table.len = 0;
 240         objd_table.allocated_len = 0;
 241         objd_table.freelist_head = -1;
 242 }
 243
 244 const char *lttng_ust_obj_get_name(int id)
 245 {
 246         struct lttng_ust_obj *obj = _objd_get(id);
 247
 248         if (!obj)
 249                 return NULL;
 250         return obj->u.s.name;
 251 }
 252
 253 void lttng_ust_objd_table_owner_cleanup(void *owner)
 254 {
 255         int i;
 256
 257         for (i = 0; i < objd_table.allocated_len; i++) {
 258                 struct lttng_ust_obj *obj;
 259
 260                 obj = _objd_get(i);
 261                 if (!obj)
 262                         continue;
 263                 if (!obj->u.s.owner)
 264                         continue;       /* skip root handles */
 265                 if (!obj->u.s.owner_ref)
 266                         continue;       /* only unref owner ref. */
 267                 if (obj->u.s.owner == owner)
 268                         (void) lttng_ust_objd_unref(i, 1);
 269         }
 270 }
 271
 272 /*
 273  * This is LTTng's own personal way to create an ABI for sessiond.
 274  * We send commands over a socket.
 275  */
 276
 277 static const struct lttng_ust_objd_ops lttng_ops;
 278 static const struct lttng_ust_objd_ops lttng_session_ops;
 279 static const struct lttng_ust_objd_ops lttng_channel_ops;
 280 static const struct lttng_ust_objd_ops lttng_enabler_ops;
 281 static const struct lttng_ust_objd_ops lttng_tracepoint_list_ops;
 282 static const struct lttng_ust_objd_ops lttng_tracepoint_field_list_ops;
 283
 284 int lttng_abi_create_root_handle(void)
 285 {
 286         int root_handle;
 287
 288         /* root handles have NULL owners */
 289         root_handle = objd_alloc(NULL, &lttng_ops, NULL, "root");
 290         return root_handle;
 291 }
 292
 293 static
 294 int lttng_is_channel_ready(struct lttng_channel *lttng_chan)
 295 {
 296         struct channel *chan;
 297         unsigned int nr_streams, exp_streams;
 298
 299         chan = lttng_chan->chan;
 300         nr_streams = channel_handle_get_nr_streams(lttng_chan->handle);
 301         exp_streams = chan->nr_streams;
 302         return nr_streams == exp_streams;
 303 }
 304
 305 static
 306 int lttng_abi_create_session(void *owner)
 307 {
 308         struct lttng_session *session;
 309         int session_objd, ret;
 310
 311         session = lttng_session_create();
 312         if (!session)
 313                 return -ENOMEM;
 314         session_objd = objd_alloc(session, &lttng_session_ops, owner, "session");
 315         if (session_objd < 0) {
 316                 ret = session_objd;
 317                 goto objd_error;
 318         }
 319         session->objd = session_objd;
 320         session->owner = owner;
 321         return session_objd;
 322
 323 objd_error:
 324         lttng_session_destroy(session);
 325         return ret;
 326 }
 327
 328 static
 329 long lttng_abi_tracer_version(int objd,
 330         struct lttng_ust_tracer_version *v)
 331 {
 332         v->major = LTTNG_UST_MAJOR_VERSION;
 333         v->minor = LTTNG_UST_MINOR_VERSION;
 334         v->patchlevel = LTTNG_UST_PATCHLEVEL_VERSION;
 335         return 0;
 336 }
 337
 338 static
 339 long lttng_abi_add_context(int objd,
 340         struct lttng_ust_context *context_param,
 341         union ust_args *uargs,
 342         struct lttng_ctx **ctx, struct lttng_session *session)
 343 {
 344         return lttng_attach_context(context_param, uargs, ctx, session);
 345 }
 346
 347 /**
 348  *      lttng_cmd - lttng control through socket commands
 349  *
 350  *      @objd: the object descriptor
 351  *      @cmd: the command
 352  *      @arg: command arg
 353  *      @uargs: UST arguments (internal)
 354  *      @owner: objd owner
 355  *
 356  *      This descriptor implements lttng commands:
 357  *      LTTNG_UST_SESSION
 358  *              Returns a LTTng trace session object descriptor
 359  *      LTTNG_UST_TRACER_VERSION
 360  *              Returns the LTTng kernel tracer version
 361  *      LTTNG_UST_TRACEPOINT_LIST
 362  *              Returns a file descriptor listing available tracepoints
 363  *      LTTNG_UST_TRACEPOINT_FIELD_LIST
 364  *              Returns a file descriptor listing available tracepoint fields
 365  *      LTTNG_UST_WAIT_QUIESCENT
 366  *              Returns after all previously running probes have completed
 367  *
 368  * The returned session will be deleted when its file descriptor is closed.
 369  */
 370 static
 371 long lttng_cmd(int objd, unsigned int cmd, unsigned long arg,
 372         union ust_args *uargs, void *owner)
 373 {
 374         switch (cmd) {
 375         case LTTNG_UST_SESSION:
 376                 return lttng_abi_create_session(owner);
 377         case LTTNG_UST_TRACER_VERSION:
 378                 return lttng_abi_tracer_version(objd,
 379                                 (struct lttng_ust_tracer_version *) arg);
 380         case LTTNG_UST_TRACEPOINT_LIST:
 381                 return lttng_abi_tracepoint_list(owner);
 382         case LTTNG_UST_TRACEPOINT_FIELD_LIST:
 383                 return lttng_abi_tracepoint_field_list(owner);
 384         case LTTNG_UST_WAIT_QUIESCENT:
 385                 synchronize_trace();
 386                 return 0;
 387         default:
 388                 return -EINVAL;
 389         }
 390 }
 391
 392 static const struct lttng_ust_objd_ops lttng_ops = {
 393         .cmd = lttng_cmd,
 394 };
 395
 396 int lttng_abi_map_channel(int session_objd,
 397                 struct lttng_ust_channel *ust_chan,
 398                 union ust_args *uargs,
 399                 void *owner)
 400 {
 401         struct lttng_session *session = objd_private(session_objd);
 402         const char *transport_name;
 403         const struct lttng_transport *transport;
 404         const char *chan_name;
 405         int chan_objd;
 406         struct lttng_ust_shm_handle *channel_handle;
 407         struct lttng_channel *lttng_chan;
 408         struct channel *chan;
 409         struct lttng_ust_lib_ring_buffer_config *config;
 410         void *chan_data;
 411         int wakeup_fd;
 412         uint64_t len;
 413         int ret;
 414         enum lttng_ust_chan_type type;
 415
 416         chan_data = uargs->channel.chan_data;
 417         wakeup_fd = uargs->channel.wakeup_fd;
 418         len = ust_chan->len;
 419         type = ust_chan->type;
 420
 421         switch (type) {
 422         case LTTNG_UST_CHAN_PER_CPU:
 423                 break;
 424         default:
 425                 ret = -EINVAL;
 426                 goto invalid;
 427         }
 428
 429         if (session->been_active) {
 430                 ret = -EBUSY;
 431                 goto active;    /* Refuse to add channel to active session */
 432         }
 433
 434         channel_handle = channel_handle_create(chan_data, len, wakeup_fd);
 435         if (!channel_handle) {
 436                 ret = -EINVAL;
 437                 goto handle_error;
 438         }
 439
 440         chan = shmp(channel_handle, channel_handle->chan);
 441         assert(chan);
 442         chan->handle = channel_handle;
 443         config = &chan->backend.config;
 444         lttng_chan = channel_get_private(chan);
 445         if (!lttng_chan) {
 446                 ret = -EINVAL;
 447                 goto alloc_error;
 448         }
 449
 450         /* Lookup transport name */
 451         switch (type) {
 452         case LTTNG_UST_CHAN_PER_CPU:
 453                 if (config->output == RING_BUFFER_MMAP) {
 454                         if (config->mode == RING_BUFFER_OVERWRITE) {
 455                                 if (config->wakeup == RING_BUFFER_WAKEUP_BY_WRITER) {
 456                                         transport_name = "relay-overwrite-mmap";
 457                                 } else {
 458                                         transport_name = "relay-overwrite-rt-mmap";
 459                                 }
 460                         } else {
 461                                 if (config->wakeup == RING_BUFFER_WAKEUP_BY_WRITER) {
 462                                         transport_name = "relay-discard-mmap";
 463                                 } else {
 464                                         transport_name = "relay-discard-rt-mmap";
 465                                 }
 466                         }
 467                 } else {
 468                         ret = -EINVAL;
 469                         goto notransport;
 470                 }
 471                 chan_name = "channel";
 472                 break;
 473         default:
 474                 ret = -EINVAL;
 475                 goto notransport;
 476         }
 477         transport = lttng_transport_find(transport_name);
 478         if (!transport) {
 479                 DBG("LTTng transport %s not found\n",
 480                        transport_name);
 481                 ret = -EINVAL;
 482                 goto notransport;
 483         }
 484
 485         chan_objd = objd_alloc(NULL, &lttng_channel_ops, owner, chan_name);
 486         if (chan_objd < 0) {
 487                 ret = chan_objd;
 488                 goto objd_error;
 489         }
 490
 491         /* Initialize our lttng chan */
 492         lttng_chan->chan = chan;
 493         lttng_chan->tstate = 1;
 494         lttng_chan->enabled = 1;
 495         lttng_chan->ctx = NULL;
 496         lttng_chan->session = session;
 497         lttng_chan->ops = &transport->ops;
 498         memcpy(&lttng_chan->chan->backend.config,
 499                 transport->client_config,
 500                 sizeof(lttng_chan->chan->backend.config));
 501         cds_list_add(&lttng_chan->node, &session->chan_head);
 502         lttng_chan->header_type = 0;
 503         lttng_chan->handle = channel_handle;
 504         lttng_chan->type = type;
 505
 506         /*
 507          * We tolerate no failure path after channel creation. It will stay
 508          * invariant for the rest of the session.
 509          */
 510         objd_set_private(chan_objd, lttng_chan);
 511         lttng_chan->objd = chan_objd;
 512         /* The channel created holds a reference on the session */
 513         objd_ref(session_objd);
 514         return chan_objd;
 515
 516         /* error path after channel was created */
 517 objd_error:
 518 notransport:
 519 alloc_error:
 520         channel_destroy(chan, channel_handle, 0);
 521         return ret;
 522
 523         /*
 524          * error path before channel creation (owning chan_data and
 525          * wakeup_fd).
 526          */
 527 handle_error:
 528 active:
 529 invalid:
 530         {
 531                 int close_ret;
 532
 533                 lttng_ust_lock_fd_tracker();
 534                 close_ret = close(wakeup_fd);
 535                 lttng_ust_unlock_fd_tracker();
 536                 if (close_ret) {
 537                         PERROR("close");
 538                 }
 539         }
 540         free(chan_data);
 541         return ret;
 542 }
 543
 544 /**
 545  *      lttng_session_cmd - lttng session object command
 546  *
 547  *      @obj: the object
 548  *      @cmd: the command
 549  *      @arg: command arg
 550  *      @uargs: UST arguments (internal)
 551  *      @owner: objd owner
 552  *
 553  *      This descriptor implements lttng commands:
 554  *      LTTNG_UST_CHANNEL
 555  *              Returns a LTTng channel object descriptor
 556  *      LTTNG_UST_ENABLE
 557  *              Enables tracing for a session (weak enable)
 558  *      LTTNG_UST_DISABLE
 559  *              Disables tracing for a session (strong disable)
 560  *
 561  * The returned channel will be deleted when its file descriptor is closed.
 562  */
 563 static
 564 long lttng_session_cmd(int objd, unsigned int cmd, unsigned long arg,
 565         union ust_args *uargs, void *owner)
 566 {
 567         struct lttng_session *session = objd_private(objd);
 568
 569         switch (cmd) {
 570         case LTTNG_UST_CHANNEL:
 571                 return lttng_abi_map_channel(objd,
 572                                 (struct lttng_ust_channel *) arg,
 573                                 uargs, owner);
 574         case LTTNG_UST_SESSION_START:
 575         case LTTNG_UST_ENABLE:
 576                 return lttng_session_enable(session);
 577         case LTTNG_UST_SESSION_STOP:
 578         case LTTNG_UST_DISABLE:
 579                 return lttng_session_disable(session);
 580         case LTTNG_UST_SESSION_STATEDUMP:
 581                 return lttng_session_statedump(session);
 582         default:
 583                 return -EINVAL;
 584         }
 585 }
 586
 587 /*
 588  * Called when the last file reference is dropped.
 589  *
 590  * Big fat note: channels and events are invariant for the whole session after
 591  * their creation. So this session destruction also destroys all channel and
 592  * event structures specific to this session (they are not destroyed when their
 593  * individual file is released).
 594  */
 595 static
 596 int lttng_release_session(int objd)
 597 {
 598         struct lttng_session *session = objd_private(objd);
 599
 600         if (session) {
 601                 lttng_session_destroy(session);
 602                 return 0;
 603         } else {
 604                 return -EINVAL;
 605         }
 606 }
 607
 608 static const struct lttng_ust_objd_ops lttng_session_ops = {
 609         .release = lttng_release_session,
 610         .cmd = lttng_session_cmd,
 611 };
 612
 613 static
 614 long lttng_tracepoint_list_cmd(int objd, unsigned int cmd, unsigned long arg,
 615         union ust_args *uargs, void *owner)
 616 {
 617         struct lttng_ust_tracepoint_list *list = objd_private(objd);
 618         struct lttng_ust_tracepoint_iter *tp =
 619                 (struct lttng_ust_tracepoint_iter *) arg;
 620         struct lttng_ust_tracepoint_iter *iter;
 621
 622         switch (cmd) {
 623         case LTTNG_UST_TRACEPOINT_LIST_GET:
 624         {
 625                 iter = lttng_ust_tracepoint_list_get_iter_next(list);
 626                 if (!iter)
 627                         return -LTTNG_UST_ERR_NOENT;
 628                 memcpy(tp, iter, sizeof(*tp));
 629                 return 0;
 630         }
 631         default:
 632                 return -EINVAL;
 633         }
 634 }
 635
 636 static
 637 int lttng_abi_tracepoint_list(void *owner)
 638 {
 639         int list_objd, ret;
 640         struct lttng_ust_tracepoint_list *list;
 641
 642         list_objd = objd_alloc(NULL, &lttng_tracepoint_list_ops, owner, "tp_list");
 643         if (list_objd < 0) {
 644                 ret = list_objd;
 645                 goto objd_error;
 646         }
 647         list = zmalloc(sizeof(*list));
 648         if (!list) {
 649                 ret = -ENOMEM;
 650                 goto alloc_error;
 651         }
 652         objd_set_private(list_objd, list);
 653
 654         /* populate list by walking on all registered probes. */
 655         ret = lttng_probes_get_event_list(list);
 656         if (ret) {
 657                 goto list_error;
 658         }
 659         return list_objd;
 660
 661 list_error:
 662         free(list);
 663 alloc_error:
 664         {
 665                 int err;
 666
 667                 err = lttng_ust_objd_unref(list_objd, 1);
 668                 assert(!err);
 669         }
 670 objd_error:
 671         return ret;
 672 }
 673
 674 static
 675 int lttng_release_tracepoint_list(int objd)
 676 {
 677         struct lttng_ust_tracepoint_list *list = objd_private(objd);
 678
 679         if (list) {
 680                 lttng_probes_prune_event_list(list);
 681                 free(list);
 682                 return 0;
 683         } else {
 684                 return -EINVAL;
 685         }
 686 }
 687
 688 static const struct lttng_ust_objd_ops lttng_tracepoint_list_ops = {
 689         .release = lttng_release_tracepoint_list,
 690         .cmd = lttng_tracepoint_list_cmd,
 691 };
 692
 693 static
 694 long lttng_tracepoint_field_list_cmd(int objd, unsigned int cmd,
 695         unsigned long arg, union ust_args *uargs, void *owner)
 696 {
 697         struct lttng_ust_field_list *list = objd_private(objd);
 698         struct lttng_ust_field_iter *tp = &uargs->field_list.entry;
 699         struct lttng_ust_field_iter *iter;
 700
 701         switch (cmd) {
 702         case LTTNG_UST_TRACEPOINT_FIELD_LIST_GET:
 703         {
 704                 iter = lttng_ust_field_list_get_iter_next(list);
 705                 if (!iter)
 706                         return -LTTNG_UST_ERR_NOENT;
 707                 memcpy(tp, iter, sizeof(*tp));
 708                 return 0;
 709         }
 710         default:
 711                 return -EINVAL;
 712         }
 713 }
 714
 715 static
 716 int lttng_abi_tracepoint_field_list(void *owner)
 717 {
 718         int list_objd, ret;
 719         struct lttng_ust_field_list *list;
 720
 721         list_objd = objd_alloc(NULL, &lttng_tracepoint_field_list_ops, owner,
 722                         "tp_field_list");
 723         if (list_objd < 0) {
 724                 ret = list_objd;
 725                 goto objd_error;
 726         }
 727         list = zmalloc(sizeof(*list));
 728         if (!list) {
 729                 ret = -ENOMEM;
 730                 goto alloc_error;
 731         }
 732         objd_set_private(list_objd, list);
 733
 734         /* populate list by walking on all registered probes. */
 735         ret = lttng_probes_get_field_list(list);
 736         if (ret) {
 737                 goto list_error;
 738         }
 739         return list_objd;
 740
 741 list_error:
 742         free(list);
 743 alloc_error:
 744         {
 745                 int err;
 746
 747                 err = lttng_ust_objd_unref(list_objd, 1);
 748                 assert(!err);
 749         }
 750 objd_error:
 751         return ret;
 752 }
 753
 754 static
 755 int lttng_release_tracepoint_field_list(int objd)
 756 {
 757         struct lttng_ust_field_list *list = objd_private(objd);
 758
 759         if (list) {
 760                 lttng_probes_prune_field_list(list);
 761                 free(list);
 762                 return 0;
 763         } else {
 764                 return -EINVAL;
 765         }
 766 }
 767
 768 static const struct lttng_ust_objd_ops lttng_tracepoint_field_list_ops = {
 769         .release = lttng_release_tracepoint_field_list,
 770         .cmd = lttng_tracepoint_field_list_cmd,
 771 };
 772
 773 static
 774 int lttng_abi_map_stream(int channel_objd, struct lttng_ust_stream *info,
 775                 union ust_args *uargs, void *owner)
 776 {
 777         struct lttng_channel *channel = objd_private(channel_objd);
 778         int ret;
 779
 780         ret = channel_handle_add_stream(channel->handle,
 781                 uargs->stream.shm_fd, uargs->stream.wakeup_fd,
 782                 info->stream_nr, info->len);
 783         if (ret)
 784                 goto error_add_stream;
 785
 786         return 0;
 787
 788 error_add_stream:
 789         return ret;
 790 }
 791
 792 static
 793 int lttng_abi_create_enabler(int channel_objd,
 794                            struct lttng_ust_event *event_param,
 795                            void *owner,
 796                            enum lttng_enabler_type type)
 797 {
 798         struct lttng_channel *channel = objd_private(channel_objd);
 799         struct lttng_enabler *enabler;
 800         int event_objd, ret;
 801
 802         event_param->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 803         event_objd = objd_alloc(NULL, &lttng_enabler_ops, owner, "enabler");
 804         if (event_objd < 0) {
 805                 ret = event_objd;
 806                 goto objd_error;
 807         }
 808         /*
 809          * We tolerate no failure path after event creation. It will stay
 810          * invariant for the rest of the session.
 811          */
 812         enabler = lttng_enabler_create(type, event_param, channel);
 813         if (!enabler) {
 814                 ret = -ENOMEM;
 815                 goto event_error;
 816         }
 817         objd_set_private(event_objd, enabler);
 818         /* The event holds a reference on the channel */
 819         objd_ref(channel_objd);
 820         return event_objd;
 821
 822 event_error:
 823         {
 824                 int err;
 825
 826                 err = lttng_ust_objd_unref(event_objd, 1);
 827                 assert(!err);
 828         }
 829 objd_error:
 830         return ret;
 831 }
 832
 833 /**
 834  *      lttng_channel_cmd - lttng control through object descriptors
 835  *
 836  *      @objd: the object descriptor
 837  *      @cmd: the command
 838  *      @arg: command arg
 839  *      @uargs: UST arguments (internal)
 840  *      @owner: objd owner
 841  *
 842  *      This object descriptor implements lttng commands:
 843  *      LTTNG_UST_STREAM
 844  *              Returns an event stream object descriptor or failure.
 845  *              (typically, one event stream records events from one CPU)
 846  *      LTTNG_UST_EVENT
 847  *              Returns an event object descriptor or failure.
 848  *      LTTNG_UST_CONTEXT
 849  *              Prepend a context field to each event in the channel
 850  *      LTTNG_UST_ENABLE
 851  *              Enable recording for events in this channel (weak enable)
 852  *      LTTNG_UST_DISABLE
 853  *              Disable recording for events in this channel (strong disable)
 854  *
 855  * Channel and event file descriptors also hold a reference on the session.
 856  */
 857 static
 858 long lttng_channel_cmd(int objd, unsigned int cmd, unsigned long arg,
 859         union ust_args *uargs, void *owner)
 860 {
 861         struct lttng_channel *channel = objd_private(objd);
 862
 863         if (cmd != LTTNG_UST_STREAM) {
 864                 /*
 865                  * Check if channel received all streams.
 866                  */
 867                 if (!lttng_is_channel_ready(channel))
 868                         return -EPERM;
 869         }
 870
 871         switch (cmd) {
 872         case LTTNG_UST_STREAM:
 873         {
 874                 struct lttng_ust_stream *stream;
 875
 876                 stream = (struct lttng_ust_stream *) arg;
 877                 /* stream used as output */
 878                 return lttng_abi_map_stream(objd, stream, uargs, owner);
 879         }
 880         case LTTNG_UST_EVENT:
 881         {
 882                 struct lttng_ust_event *event_param =
 883                         (struct lttng_ust_event *) arg;
 884
 885                 if (strutils_is_star_glob_pattern(event_param->name)) {
 886                         /*
 887                          * If the event name is a star globbing pattern,
 888                          * we create the special star globbing enabler.
 889                          */
 890                         return lttng_abi_create_enabler(objd, event_param,
 891                                         owner, LTTNG_ENABLER_STAR_GLOB);
 892                 } else {
 893                         return lttng_abi_create_enabler(objd, event_param,
 894                                         owner, LTTNG_ENABLER_EVENT);
 895                 }
 896         }
 897         case LTTNG_UST_CONTEXT:
 898                 return lttng_abi_add_context(objd,
 899                                 (struct lttng_ust_context *) arg, uargs,
 900                                 &channel->ctx, channel->session);
 901         case LTTNG_UST_ENABLE:
 902                 return lttng_channel_enable(channel);
 903         case LTTNG_UST_DISABLE:
 904                 return lttng_channel_disable(channel);
 905         case LTTNG_UST_FLUSH_BUFFER:
 906                 return channel->ops->flush_buffer(channel->chan, channel->handle);
 907         default:
 908                 return -EINVAL;
 909         }
 910 }
 911
 912 static
 913 int lttng_channel_release(int objd)
 914 {
 915         struct lttng_channel *channel = objd_private(objd);
 916
 917         if (channel)
 918                 return lttng_ust_objd_unref(channel->session->objd, 0);
 919         return 0;
 920 }
 921
 922 static const struct lttng_ust_objd_ops lttng_channel_ops = {
 923         .release = lttng_channel_release,
 924         .cmd = lttng_channel_cmd,
 925 };
 926
 927 /**
 928  *      lttng_enabler_cmd - lttng control through object descriptors
 929  *
 930  *      @objd: the object descriptor
 931  *      @cmd: the command
 932  *      @arg: command arg
 933  *      @uargs: UST arguments (internal)
 934  *      @owner: objd owner
 935  *
 936  *      This object descriptor implements lttng commands:
 937  *      LTTNG_UST_CONTEXT
 938  *              Prepend a context field to each record of events of this
 939  *              enabler.
 940  *      LTTNG_UST_ENABLE
 941  *              Enable recording for this enabler
 942  *      LTTNG_UST_DISABLE
 943  *              Disable recording for this enabler
 944  *      LTTNG_UST_FILTER
 945  *              Attach a filter to an enabler.
 946  *      LTTNG_UST_EXCLUSION
 947  *              Attach exclusions to an enabler.
 948  */
 949 static
 950 long lttng_enabler_cmd(int objd, unsigned int cmd, unsigned long arg,
 951         union ust_args *uargs, void *owner)
 952 {
 953         struct lttng_enabler *enabler = objd_private(objd);
 954
 955         switch (cmd) {
 956         case LTTNG_UST_CONTEXT:
 957                 return lttng_enabler_attach_context(enabler,
 958                                 (struct lttng_ust_context *) arg);
 959         case LTTNG_UST_ENABLE:
 960                 return lttng_enabler_enable(enabler);
 961         case LTTNG_UST_DISABLE:
 962                 return lttng_enabler_disable(enabler);
 963         case LTTNG_UST_FILTER:
 964         {
 965                 int ret;
 966
 967                 ret = lttng_enabler_attach_bytecode(enabler,
 968                                 (struct lttng_ust_filter_bytecode_node *) arg);
 969                 if (ret)
 970                         return ret;
 971                 return 0;
 972         }
 973         case LTTNG_UST_EXCLUSION:
 974         {
 975                 return lttng_enabler_attach_exclusion(enabler,
 976                                 (struct lttng_ust_excluder_node *) arg);
 977         }
 978         default:
 979                 return -EINVAL;
 980         }
 981 }
 982
 983 static
 984 int lttng_enabler_release(int objd)
 985 {
 986         struct lttng_enabler *enabler = objd_private(objd);
 987
 988         if (enabler)
 989                 return lttng_ust_objd_unref(enabler->chan->objd, 0);
 990         return 0;
 991 }
 992
 993 static const struct lttng_ust_objd_ops lttng_enabler_ops = {
 994         .release = lttng_enabler_release,
 995         .cmd = lttng_enabler_cmd,
 996 };
 997
 998 void lttng_ust_abi_exit(void)
 999 {
1000         lttng_ust_abi_close_in_progress = 1;
1001         ust_lock_nocheck();
1002         objd_table_destroy();
1003         ust_unlock();
1004         lttng_ust_abi_close_in_progress = 0;
1005 }