liblttng-ust/lttng-ust-abi.c

   1 /*
   2  * lttng-ust-abi.c
   3  *
   4  * Copyright 2010-2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * LTTng UST ABI
   7  *
   8  * Mimic system calls for:
   9  * - session creation, returns an object descriptor or failure.
  10  *   - channel creation, returns an object descriptor or failure.
  11  *     - Operates on a session object descriptor
  12  *     - Takes all channel options as parameters.
  13  *   - stream get, returns an object descriptor or failure.
  14  *     - Operates on a channel object descriptor.
  15  *   - stream notifier get, returns an object descriptor or failure.
  16  *     - Operates on a channel object descriptor.
  17  *   - event creation, returns an object descriptor or failure.
  18  *     - Operates on a channel object descriptor
  19  *     - Takes an event name as parameter
  20  *     - Takes an instrumentation source as parameter
  21  *       - e.g. tracepoints, dynamic_probes...
  22  *     - Takes instrumentation source specific arguments.
  23  *
  24  * Dual LGPL v2.1/GPL v2 license.
  25  */
  26
  27 #include <lttng/ust-abi.h>
  28 #include <urcu/compiler.h>
  29 #include <urcu/list.h>
  30 #include <lttng/ust-events.h>
  31 #include <lttng/usterr-signal-safe.h>
  32 #include "lttng/core.h"
  33 #include "ltt-tracer.h"
  34
  35 /*
  36  * Object descriptor table. Should be protected from concurrent access
  37  * by the caller.
  38  */
  39
  40 struct lttng_ust_obj {
  41         union {
  42                 struct {
  43                         void *private_data;
  44                         const struct lttng_ust_objd_ops *ops;
  45                         int f_count;
  46                 } s;
  47                 int freelist_next;      /* offset freelist. end is -1. */
  48         } u;
  49 };
  50
  51 struct lttng_ust_objd_table {
  52         struct lttng_ust_obj *array;
  53         unsigned int len, allocated_len;
  54         int freelist_head;              /* offset freelist head. end is -1 */
  55 };
  56
  57 static struct lttng_ust_objd_table objd_table = {
  58         .freelist_head = -1,
  59 };
  60
  61 static
  62 int objd_alloc(void *private_data, const struct lttng_ust_objd_ops *ops)
  63 {
  64         struct lttng_ust_obj *obj;
  65
  66         if (objd_table.freelist_head != -1) {
  67                 obj = &objd_table.array[objd_table.freelist_head];
  68                 objd_table.freelist_head = obj->u.freelist_next;
  69                 goto end;
  70         }
  71
  72         if (objd_table.len >= objd_table.allocated_len) {
  73                 unsigned int new_allocated_len, old_allocated_len;
  74                 struct lttng_ust_obj *new_table, *old_table;
  75
  76                 old_allocated_len = objd_table.allocated_len;
  77                 old_table = objd_table.array;
  78                 if (!old_allocated_len)
  79                         new_allocated_len = 1;
  80                 else
  81                         new_allocated_len = old_allocated_len << 1;
  82                 new_table = zmalloc(sizeof(struct lttng_ust_obj) * new_allocated_len);
  83                 if (!new_table)
  84                         return -ENOMEM;
  85                 memcpy(new_table, old_table,
  86                        sizeof(struct lttng_ust_obj) * old_allocated_len);
  87                 free(old_table);
  88                 objd_table.array = new_table;
  89                 objd_table.allocated_len = new_allocated_len;
  90         }
  91         obj = &objd_table.array[objd_table.len];
  92         objd_table.len++;
  93 end:
  94         obj->u.s.private_data = private_data;
  95         obj->u.s.ops = ops;
  96         obj->u.s.f_count = 2;   /* count == 1 : object is allocated */
  97                                 /* count == 2 : allocated + hold ref */
  98         return obj - objd_table.array;
  99 }
 100
 101 static
 102 struct lttng_ust_obj *_objd_get(int id)
 103 {
 104         if (id >= objd_table.len)
 105                 return NULL;
 106         if (!objd_table.array[id].u.s.f_count)
 107                 return NULL;
 108         return &objd_table.array[id];
 109 }
 110
 111 static
 112 void *objd_private(int id)
 113 {
 114         struct lttng_ust_obj *obj = _objd_get(id);
 115         assert(obj);
 116         return obj->u.s.private_data;
 117 }
 118
 119 static
 120 void objd_set_private(int id, void *private_data)
 121 {
 122         struct lttng_ust_obj *obj = _objd_get(id);
 123         assert(obj);
 124         obj->u.s.private_data = private_data;
 125 }
 126
 127 const struct lttng_ust_objd_ops *objd_ops(int id)
 128 {
 129         struct lttng_ust_obj *obj = _objd_get(id);
 130
 131         if (!obj)
 132                 return NULL;
 133         return obj->u.s.ops;
 134 }
 135
 136 static
 137 void objd_free(int id)
 138 {
 139         struct lttng_ust_obj *obj = _objd_get(id);
 140
 141         assert(obj);
 142         obj->u.freelist_next = objd_table.freelist_head;
 143         objd_table.freelist_head = obj - objd_table.array;
 144         assert(obj->u.s.f_count == 1);
 145         obj->u.s.f_count = 0;   /* deallocated */
 146 }
 147
 148 static
 149 void objd_ref(int id)
 150 {
 151         struct lttng_ust_obj *obj = _objd_get(id);
 152         obj->u.s.f_count++;
 153 }
 154
 155 int lttng_ust_objd_unref(int id)
 156 {
 157         struct lttng_ust_obj *obj = _objd_get(id);
 158
 159         if (!obj)
 160                 return -EINVAL;
 161         if (obj->u.s.f_count == 1) {
 162                 ERR("Reference counting error\n");
 163                 return -EINVAL;
 164         }
 165         if ((--obj->u.s.f_count) == 1) {
 166                 const struct lttng_ust_objd_ops *ops = objd_ops(id);
 167
 168                 if (ops->release)
 169                         ops->release(id);
 170                 objd_free(id);
 171         }
 172         return 0;
 173 }
 174
 175 static
 176 void objd_table_destroy(void)
 177 {
 178         int i;
 179
 180         for (i = 0; i < objd_table.allocated_len; i++)
 181                 (void) lttng_ust_objd_unref(i);
 182         free(objd_table.array);
 183         objd_table.array = NULL;
 184         objd_table.len = 0;
 185         objd_table.allocated_len = 0;
 186         objd_table.freelist_head = -1;
 187 }
 188
 189 /*
 190  * This is LTTng's own personal way to create an ABI for sessiond.
 191  * We send commands over a socket.
 192  */
 193
 194 static const struct lttng_ust_objd_ops lttng_ops;
 195 static const struct lttng_ust_objd_ops lttng_session_ops;
 196 static const struct lttng_ust_objd_ops lttng_channel_ops;
 197 static const struct lttng_ust_objd_ops lttng_metadata_ops;
 198 static const struct lttng_ust_objd_ops lttng_event_ops;
 199 static const struct lttng_ust_objd_ops lib_ring_buffer_objd_ops;
 200
 201 enum channel_type {
 202         PER_CPU_CHANNEL,
 203         METADATA_CHANNEL,
 204 };
 205
 206 int lttng_abi_create_root_handle(void)
 207 {
 208         int root_handle;
 209
 210         root_handle = objd_alloc(NULL, &lttng_ops);
 211         return root_handle;
 212 }
 213
 214 static
 215 int lttng_abi_create_session(void)
 216 {
 217         struct ltt_session *session;
 218         int session_objd, ret;
 219
 220         session = ltt_session_create();
 221         if (!session)
 222                 return -ENOMEM;
 223         session_objd = objd_alloc(session, &lttng_session_ops);
 224         if (session_objd < 0) {
 225                 ret = session_objd;
 226                 goto objd_error;
 227         }
 228         session->objd = session_objd;
 229         return session_objd;
 230
 231 objd_error:
 232         ltt_session_destroy(session);
 233         return ret;
 234 }
 235
 236 #if 0
 237 static
 238 int lttng_abi_tracepoint_list(void)
 239 {
 240         int list_objd, ret;
 241
 242         /* TODO: Create list private data */
 243         list_objd = objd_alloc(NULL, &lttng_tracepoint_list_ops);
 244         if (list_objd < 0) {
 245                 ret = list_objd;
 246                 goto objd_error;
 247         }
 248
 249         return list_objd;
 250
 251 objd_error:
 252         return ret;
 253 }
 254 #endif //0
 255
 256 static
 257 long lttng_abi_tracer_version(int objd,
 258         struct lttng_ust_tracer_version *v)
 259 {
 260         v->version = LTTNG_UST_VERSION;
 261         v->patchlevel = LTTNG_UST_PATCHLEVEL;
 262         v->sublevel = LTTNG_UST_SUBLEVEL;
 263         return 0;
 264 }
 265
 266 static
 267 long lttng_abi_add_context(int objd,
 268         struct lttng_ust_context *context_param,
 269         struct lttng_ctx **ctx, struct ltt_session *session)
 270 {
 271         if (session->been_active)
 272                 return -EPERM;
 273
 274         switch (context_param->ctx) {
 275         case LTTNG_UST_CONTEXT_PTHREAD_ID:
 276                 return lttng_add_pthread_id_to_ctx(ctx);
 277         case LTTNG_UST_CONTEXT_VTID:
 278                 return lttng_add_vtid_to_ctx(ctx);
 279         case LTTNG_UST_CONTEXT_VPID:
 280                 return lttng_add_vpid_to_ctx(ctx);
 281         case LTTNG_UST_CONTEXT_PROCNAME:
 282                 return lttng_add_procname_to_ctx(ctx);
 283         default:
 284                 return -EINVAL;
 285         }
 286 }
 287
 288 /**
 289  *      lttng_cmd - lttng control through socket commands
 290  *
 291  *      @objd: the object descriptor
 292  *      @cmd: the command
 293  *      @arg: command arg
 294  *
 295  *      This descriptor implements lttng commands:
 296  *      LTTNG_UST_SESSION
 297  *              Returns a LTTng trace session object descriptor
 298  *      LTTNG_UST_TRACER_VERSION
 299  *              Returns the LTTng kernel tracer version
 300  *      LTTNG_UST_TRACEPOINT_LIST
 301  *              Returns a file descriptor listing available tracepoints
 302  *      LTTNG_UST_WAIT_QUIESCENT
 303  *              Returns after all previously running probes have completed
 304  *
 305  * The returned session will be deleted when its file descriptor is closed.
 306  */
 307 static
 308 long lttng_cmd(int objd, unsigned int cmd, unsigned long arg)
 309 {
 310         switch (cmd) {
 311         case LTTNG_UST_SESSION:
 312                 return lttng_abi_create_session();
 313         case LTTNG_UST_TRACER_VERSION:
 314                 return lttng_abi_tracer_version(objd,
 315                                 (struct lttng_ust_tracer_version *) arg);
 316         case LTTNG_UST_TRACEPOINT_LIST:
 317                 return -ENOSYS; //TODO
 318                 //return lttng_abi_tracepoint_list();
 319         case LTTNG_UST_WAIT_QUIESCENT:
 320                 synchronize_trace();
 321                 return 0;
 322         default:
 323                 return -EINVAL;
 324         }
 325 }
 326
 327 static const struct lttng_ust_objd_ops lttng_ops = {
 328         .cmd = lttng_cmd,
 329 };
 330
 331 /*
 332  * We tolerate no failure in this function (if one happens, we print a dmesg
 333  * error, but cannot return any error, because the channel information is
 334  * invariant.
 335  */
 336 static
 337 void lttng_metadata_create_events(int channel_objd)
 338 {
 339         struct ltt_channel *channel = objd_private(channel_objd);
 340         static struct lttng_ust_event metadata_params = {
 341                 .instrumentation = LTTNG_UST_TRACEPOINT,
 342                 .name = "lttng_metadata",
 343         };
 344         struct ltt_event *event;
 345         int ret;
 346
 347         /*
 348          * We tolerate no failure path after event creation. It will stay
 349          * invariant for the rest of the session.
 350          */
 351         event = ltt_event_create(channel, &metadata_params, NULL);
 352         if (!event) {
 353                 ret = -EINVAL;
 354                 goto create_error;
 355         }
 356         return;
 357
 358 create_error:
 359         WARN_ON(1);
 360         return;         /* not allowed to return error */
 361 }
 362
 363 int lttng_abi_create_channel(int session_objd,
 364                              struct lttng_ust_channel *chan_param,
 365                              enum channel_type channel_type)
 366 {
 367         struct ltt_session *session = objd_private(session_objd);
 368         const struct lttng_ust_objd_ops *ops;
 369         const char *transport_name;
 370         struct ltt_channel *chan;
 371         int chan_objd;
 372         int ret = 0;
 373
 374         chan_objd = objd_alloc(NULL, &lttng_channel_ops);
 375         if (chan_objd < 0) {
 376                 ret = chan_objd;
 377                 goto objd_error;
 378         }
 379         switch (channel_type) {
 380         case PER_CPU_CHANNEL:
 381                 if (chan_param->output == LTTNG_UST_MMAP) {
 382                         transport_name = chan_param->overwrite ?
 383                                 "relay-overwrite-mmap" : "relay-discard-mmap";
 384                 } else {
 385                         return -EINVAL;
 386                 }
 387                 ops = &lttng_channel_ops;
 388                 break;
 389         case METADATA_CHANNEL:
 390                 if (chan_param->output == LTTNG_UST_MMAP)
 391                         transport_name = "relay-metadata-mmap";
 392                 else
 393                         return -EINVAL;
 394                 ops = &lttng_metadata_ops;
 395                 break;
 396         default:
 397                 transport_name = "<unknown>";
 398                 break;
 399         }
 400         /*
 401          * We tolerate no failure path after channel creation. It will stay
 402          * invariant for the rest of the session.
 403          */
 404         chan = ltt_channel_create(session, transport_name, NULL,
 405                                   chan_param->subbuf_size,
 406                                   chan_param->num_subbuf,
 407                                   chan_param->switch_timer_interval,
 408                                   chan_param->read_timer_interval,
 409                                   &chan_param->shm_fd,
 410                                   &chan_param->wait_fd,
 411                                   &chan_param->memory_map_size);
 412         if (!chan) {
 413                 ret = -EINVAL;
 414                 goto chan_error;
 415         }
 416         objd_set_private(chan_objd, chan);
 417         chan->objd = chan_objd;
 418         if (channel_type == METADATA_CHANNEL) {
 419                 session->metadata = chan;
 420                 lttng_metadata_create_events(chan_objd);
 421         }
 422
 423         /* The channel created holds a reference on the session */
 424         objd_ref(session_objd);
 425
 426         return chan_objd;
 427
 428 chan_error:
 429         {
 430                 int err;
 431
 432                 err = lttng_ust_objd_unref(chan_objd);
 433                 assert(!err);
 434         }
 435 objd_error:
 436         return ret;
 437 }
 438
 439 /**
 440  *      lttng_session_cmd - lttng session object command
 441  *
 442  *      @obj: the object
 443  *      @cmd: the command
 444  *      @arg: command arg
 445  *
 446  *      This descriptor implements lttng commands:
 447  *      LTTNG_UST_CHANNEL
 448  *              Returns a LTTng channel object descriptor
 449  *      LTTNG_UST_ENABLE
 450  *              Enables tracing for a session (weak enable)
 451  *      LTTNG_UST_DISABLE
 452  *              Disables tracing for a session (strong disable)
 453  *      LTTNG_UST_METADATA
 454  *              Returns a LTTng metadata object descriptor
 455  *
 456  * The returned channel will be deleted when its file descriptor is closed.
 457  */
 458 static
 459 long lttng_session_cmd(int objd, unsigned int cmd, unsigned long arg)
 460 {
 461         struct ltt_session *session = objd_private(objd);
 462
 463         switch (cmd) {
 464         case LTTNG_UST_CHANNEL:
 465                 return lttng_abi_create_channel(objd,
 466                                 (struct lttng_ust_channel *) arg,
 467                                 PER_CPU_CHANNEL);
 468         case LTTNG_UST_SESSION_START:
 469         case LTTNG_UST_ENABLE:
 470                 return ltt_session_enable(session);
 471         case LTTNG_UST_SESSION_STOP:
 472         case LTTNG_UST_DISABLE:
 473                 return ltt_session_disable(session);
 474         case LTTNG_UST_METADATA:
 475                 return lttng_abi_create_channel(objd,
 476                                 (struct lttng_ust_channel *) arg,
 477                                 METADATA_CHANNEL);
 478         default:
 479                 return -EINVAL;
 480         }
 481 }
 482
 483 /*
 484  * Called when the last file reference is dropped.
 485  *
 486  * Big fat note: channels and events are invariant for the whole session after
 487  * their creation. So this session destruction also destroys all channel and
 488  * event structures specific to this session (they are not destroyed when their
 489  * individual file is released).
 490  */
 491 static
 492 int lttng_release_session(int objd)
 493 {
 494         struct ltt_session *session = objd_private(objd);
 495
 496         if (session) {
 497                 ltt_session_destroy(session);
 498                 return 0;
 499         } else {
 500                 return -EINVAL;
 501         }
 502 }
 503
 504 static const struct lttng_ust_objd_ops lttng_session_ops = {
 505         .release = lttng_release_session,
 506         .cmd = lttng_session_cmd,
 507 };
 508
 509 struct stream_priv_data {
 510         struct lttng_ust_lib_ring_buffer *buf;
 511         struct ltt_channel *ltt_chan;
 512 };
 513
 514 static
 515 int lttng_abi_open_stream(int channel_objd, struct lttng_ust_stream *info)
 516 {
 517         struct ltt_channel *channel = objd_private(channel_objd);
 518         struct lttng_ust_lib_ring_buffer *buf;
 519         struct stream_priv_data *priv;
 520         int stream_objd, ret;
 521
 522         buf = channel->ops->buffer_read_open(channel->chan, channel->handle,
 523                         &info->shm_fd, &info->wait_fd, &info->memory_map_size);
 524         if (!buf)
 525                 return -ENOENT;
 526
 527         priv = zmalloc(sizeof(*priv));
 528         if (!priv) {
 529                 ret = -ENOMEM;
 530                 goto alloc_error;
 531         }
 532         priv->buf = buf;
 533         priv->ltt_chan = channel;
 534         stream_objd = objd_alloc(priv, &lib_ring_buffer_objd_ops);
 535         if (stream_objd < 0) {
 536                 ret = stream_objd;
 537                 goto objd_error;
 538         }
 539         /* Hold a reference on the channel object descriptor */
 540         objd_ref(channel_objd);
 541         return stream_objd;
 542
 543 objd_error:
 544         free(priv);
 545 alloc_error:
 546         channel->ops->buffer_read_close(buf, channel->handle);
 547         return ret;
 548 }
 549
 550 static
 551 int lttng_abi_create_event(int channel_objd,
 552                            struct lttng_ust_event *event_param)
 553 {
 554         struct ltt_channel *channel = objd_private(channel_objd);
 555         struct ltt_event *event;
 556         int event_objd, ret;
 557
 558         event_param->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 559         event_objd = objd_alloc(NULL, &lttng_event_ops);
 560         if (event_objd < 0) {
 561                 ret = event_objd;
 562                 goto objd_error;
 563         }
 564         /*
 565          * We tolerate no failure path after event creation. It will stay
 566          * invariant for the rest of the session.
 567          */
 568         event = ltt_event_create(channel, event_param, NULL);
 569         if (!event) {
 570                 ret = -EINVAL;
 571                 goto event_error;
 572         }
 573         objd_set_private(event_objd, event);
 574         /* The event holds a reference on the channel */
 575         objd_ref(channel_objd);
 576         return event_objd;
 577
 578 event_error:
 579         {
 580                 int err;
 581
 582                 err = lttng_ust_objd_unref(event_objd);
 583                 assert(!err);
 584         }
 585 objd_error:
 586         return ret;
 587 }
 588
 589 /**
 590  *      lttng_channel_cmd - lttng control through object descriptors
 591  *
 592  *      @objd: the object descriptor
 593  *      @cmd: the command
 594  *      @arg: command arg
 595  *
 596  *      This object descriptor implements lttng commands:
 597  *      LTTNG_UST_STREAM
 598  *              Returns an event stream object descriptor or failure.
 599  *              (typically, one event stream records events from one CPU)
 600  *      LTTNG_UST_EVENT
 601  *              Returns an event object descriptor or failure.
 602  *      LTTNG_UST_CONTEXT
 603  *              Prepend a context field to each event in the channel
 604  *      LTTNG_UST_ENABLE
 605  *              Enable recording for events in this channel (weak enable)
 606  *      LTTNG_UST_DISABLE
 607  *              Disable recording for events in this channel (strong disable)
 608  *
 609  * Channel and event file descriptors also hold a reference on the session.
 610  */
 611 static
 612 long lttng_channel_cmd(int objd, unsigned int cmd, unsigned long arg)
 613 {
 614         struct ltt_channel *channel = objd_private(objd);
 615
 616         switch (cmd) {
 617         case LTTNG_UST_STREAM:
 618         {
 619                 struct lttng_ust_stream *stream;
 620
 621                 stream = (struct lttng_ust_stream *) arg;
 622                 /* stream used as output */
 623                 return lttng_abi_open_stream(objd, stream);
 624         }
 625         case LTTNG_UST_EVENT:
 626                 return lttng_abi_create_event(objd, (struct lttng_ust_event *) arg);
 627         case LTTNG_UST_CONTEXT:
 628                 return lttng_abi_add_context(objd,
 629                                 (struct lttng_ust_context *) arg,
 630                                 &channel->ctx, channel->session);
 631         case LTTNG_UST_ENABLE:
 632                 return ltt_channel_enable(channel);
 633         case LTTNG_UST_DISABLE:
 634                 return ltt_channel_disable(channel);
 635         case LTTNG_UST_FLUSH_BUFFER:
 636                 return channel->ops->flush_buffer(channel->chan, channel->handle);
 637         default:
 638                 return -EINVAL;
 639         }
 640 }
 641
 642 /**
 643  *      lttng_metadata_cmd - lttng control through object descriptors
 644  *
 645  *      @objd: the object descriptor
 646  *      @cmd: the command
 647  *      @arg: command arg
 648  *
 649  *      This object descriptor implements lttng commands:
 650  *      LTTNG_UST_STREAM
 651  *              Returns an event stream file descriptor or failure.
 652  *
 653  * Channel and event file descriptors also hold a reference on the session.
 654  */
 655 static
 656 long lttng_metadata_cmd(int objd, unsigned int cmd, unsigned long arg)
 657 {
 658         struct ltt_channel *channel = objd_private(objd);
 659
 660         switch (cmd) {
 661         case LTTNG_UST_STREAM:
 662         {
 663                 struct lttng_ust_stream *stream;
 664
 665                 stream = (struct lttng_ust_stream *) arg;
 666                 /* stream used as output */
 667                 return lttng_abi_open_stream(objd, stream);
 668         }
 669         case LTTNG_UST_FLUSH_BUFFER:
 670                 return channel->ops->flush_buffer(channel->chan, channel->handle);
 671         default:
 672                 return -EINVAL;
 673         }
 674 }
 675
 676 #if 0
 677 /**
 678  *      lttng_channel_poll - lttng stream addition/removal monitoring
 679  *
 680  *      @file: the file
 681  *      @wait: poll table
 682  */
 683 unsigned int lttng_channel_poll(struct file *file, poll_table *wait)
 684 {
 685         struct ltt_channel *channel = file->private_data;
 686         unsigned int mask = 0;
 687
 688         if (file->f_mode & FMODE_READ) {
 689                 poll_wait_set_exclusive(wait);
 690                 poll_wait(file, channel->ops->get_hp_wait_queue(channel->chan),
 691                           wait);
 692
 693                 if (channel->ops->is_disabled(channel->chan))
 694                         return POLLERR;
 695                 if (channel->ops->is_finalized(channel->chan))
 696                         return POLLHUP;
 697                 if (channel->ops->buffer_has_read_closed_stream(channel->chan))
 698                         return POLLIN | POLLRDNORM;
 699                 return 0;
 700         }
 701         return mask;
 702
 703 }
 704 #endif //0
 705
 706 static
 707 int lttng_channel_release(int objd)
 708 {
 709         struct ltt_channel *channel = objd_private(objd);
 710
 711         if (channel)
 712                 return lttng_ust_objd_unref(channel->session->objd);
 713         return 0;
 714 }
 715
 716 static const struct lttng_ust_objd_ops lttng_channel_ops = {
 717         .release = lttng_channel_release,
 718         //.poll = lttng_channel_poll,
 719         .cmd = lttng_channel_cmd,
 720 };
 721
 722 static const struct lttng_ust_objd_ops lttng_metadata_ops = {
 723         .release = lttng_channel_release,
 724         .cmd = lttng_metadata_cmd,
 725 };
 726
 727 /**
 728  *      lttng_rb_cmd - lttng ring buffer control through object descriptors
 729  *
 730  *      @objd: the object descriptor
 731  *      @cmd: the command
 732  *      @arg: command arg
 733  *
 734  *      This object descriptor implements lttng commands:
 735  *              (None for now. Access is done directly though shm.)
 736  */
 737 static
 738 long lttng_rb_cmd(int objd, unsigned int cmd, unsigned long arg)
 739 {
 740         switch (cmd) {
 741         default:
 742                 return -EINVAL;
 743         }
 744 }
 745
 746 static
 747 int lttng_rb_release(int objd)
 748 {
 749         struct stream_priv_data *priv = objd_private(objd);
 750         struct lttng_ust_lib_ring_buffer *buf;
 751         struct ltt_channel *channel;
 752
 753         if (priv) {
 754                 buf = priv->buf;
 755                 channel = priv->ltt_chan;
 756                 free(priv);
 757                 channel->ops->buffer_read_close(buf, channel->handle);
 758
 759                 return lttng_ust_objd_unref(channel->objd);
 760         }
 761         return 0;
 762 }
 763
 764 static const struct lttng_ust_objd_ops lib_ring_buffer_objd_ops = {
 765         .release = lttng_rb_release,
 766         .cmd = lttng_rb_cmd,
 767 };
 768
 769 /**
 770  *      lttng_event_cmd - lttng control through object descriptors
 771  *
 772  *      @objd: the object descriptor
 773  *      @cmd: the command
 774  *      @arg: command arg
 775  *
 776  *      This object descriptor implements lttng commands:
 777  *      LTTNG_UST_CONTEXT
 778  *              Prepend a context field to each record of this event
 779  *      LTTNG_UST_ENABLE
 780  *              Enable recording for this event (weak enable)
 781  *      LTTNG_UST_DISABLE
 782  *              Disable recording for this event (strong disable)
 783  */
 784 static
 785 long lttng_event_cmd(int objd, unsigned int cmd, unsigned long arg)
 786 {
 787         struct ltt_event *event = objd_private(objd);
 788
 789         switch (cmd) {
 790         case LTTNG_UST_CONTEXT:
 791                 return lttng_abi_add_context(objd,
 792                                 (struct lttng_ust_context *) arg,
 793                                 &event->ctx, event->chan->session);
 794         case LTTNG_UST_ENABLE:
 795                 return ltt_event_enable(event);
 796         case LTTNG_UST_DISABLE:
 797                 return ltt_event_disable(event);
 798         default:
 799                 return -EINVAL;
 800         }
 801 }
 802
 803 static
 804 int lttng_event_release(int objd)
 805 {
 806         struct ltt_event *event = objd_private(objd);
 807
 808         if (event)
 809                 return lttng_ust_objd_unref(event->chan->objd);
 810         return 0;
 811 }
 812
 813 /* TODO: filter control ioctl */
 814 static const struct lttng_ust_objd_ops lttng_event_ops = {
 815         .release = lttng_event_release,
 816         .cmd = lttng_event_cmd,
 817 };
 818
 819 void lttng_ust_abi_exit(void)
 820 {
 821         objd_table_destroy();
 822 }