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/ust-version.h>
  32 #include <usterr-signal-safe.h>
  33 #include <helper.h>
  34 #include "ltt-tracer.h"
  35 #include "tracepoint-internal.h"
  36
  37 struct ltt_tracepoint_list {
  38         struct tracepoint_iter iter;
  39         int got_first;
  40 };
  41
  42 static int lttng_ust_abi_close_in_progress;
  43
  44 static
  45 int lttng_abi_tracepoint_list(void);
  46
  47 /*
  48  * Object descriptor table. Should be protected from concurrent access
  49  * by the caller.
  50  */
  51
  52 struct lttng_ust_obj {
  53         union {
  54                 struct {
  55                         void *private_data;
  56                         const struct lttng_ust_objd_ops *ops;
  57                         int f_count;
  58                 } s;
  59                 int freelist_next;      /* offset freelist. end is -1. */
  60         } u;
  61 };
  62
  63 struct lttng_ust_objd_table {
  64         struct lttng_ust_obj *array;
  65         unsigned int len, allocated_len;
  66         int freelist_head;              /* offset freelist head. end is -1 */
  67 };
  68
  69 static struct lttng_ust_objd_table objd_table = {
  70         .freelist_head = -1,
  71 };
  72
  73 static
  74 int objd_alloc(void *private_data, const struct lttng_ust_objd_ops *ops)
  75 {
  76         struct lttng_ust_obj *obj;
  77
  78         if (objd_table.freelist_head != -1) {
  79                 obj = &objd_table.array[objd_table.freelist_head];
  80                 objd_table.freelist_head = obj->u.freelist_next;
  81                 goto end;
  82         }
  83
  84         if (objd_table.len >= objd_table.allocated_len) {
  85                 unsigned int new_allocated_len, old_allocated_len;
  86                 struct lttng_ust_obj *new_table, *old_table;
  87
  88                 old_allocated_len = objd_table.allocated_len;
  89                 old_table = objd_table.array;
  90                 if (!old_allocated_len)
  91                         new_allocated_len = 1;
  92                 else
  93                         new_allocated_len = old_allocated_len << 1;
  94                 new_table = zmalloc(sizeof(struct lttng_ust_obj) * new_allocated_len);
  95                 if (!new_table)
  96                         return -ENOMEM;
  97                 memcpy(new_table, old_table,
  98                        sizeof(struct lttng_ust_obj) * old_allocated_len);
  99                 free(old_table);
 100                 objd_table.array = new_table;
 101                 objd_table.allocated_len = new_allocated_len;
 102         }
 103         obj = &objd_table.array[objd_table.len];
 104         objd_table.len++;
 105 end:
 106         obj->u.s.private_data = private_data;
 107         obj->u.s.ops = ops;
 108         obj->u.s.f_count = 2;   /* count == 1 : object is allocated */
 109                                 /* count == 2 : allocated + hold ref */
 110         return obj - objd_table.array;
 111 }
 112
 113 static
 114 struct lttng_ust_obj *_objd_get(int id)
 115 {
 116         if (id >= objd_table.len)
 117                 return NULL;
 118         if (!objd_table.array[id].u.s.f_count)
 119                 return NULL;
 120         return &objd_table.array[id];
 121 }
 122
 123 static
 124 void *objd_private(int id)
 125 {
 126         struct lttng_ust_obj *obj = _objd_get(id);
 127         assert(obj);
 128         return obj->u.s.private_data;
 129 }
 130
 131 static
 132 void objd_set_private(int id, void *private_data)
 133 {
 134         struct lttng_ust_obj *obj = _objd_get(id);
 135         assert(obj);
 136         obj->u.s.private_data = private_data;
 137 }
 138
 139 const struct lttng_ust_objd_ops *objd_ops(int id)
 140 {
 141         struct lttng_ust_obj *obj = _objd_get(id);
 142
 143         if (!obj)
 144                 return NULL;
 145         return obj->u.s.ops;
 146 }
 147
 148 static
 149 void objd_free(int id)
 150 {
 151         struct lttng_ust_obj *obj = _objd_get(id);
 152
 153         assert(obj);
 154         obj->u.freelist_next = objd_table.freelist_head;
 155         objd_table.freelist_head = obj - objd_table.array;
 156         assert(obj->u.s.f_count == 1);
 157         obj->u.s.f_count = 0;   /* deallocated */
 158 }
 159
 160 static
 161 void objd_ref(int id)
 162 {
 163         struct lttng_ust_obj *obj = _objd_get(id);
 164         obj->u.s.f_count++;
 165 }
 166
 167 int lttng_ust_objd_unref(int id)
 168 {
 169         struct lttng_ust_obj *obj = _objd_get(id);
 170
 171         if (!obj)
 172                 return -EINVAL;
 173         if (obj->u.s.f_count == 1) {
 174                 ERR("Reference counting error\n");
 175                 return -EINVAL;
 176         }
 177         if ((--obj->u.s.f_count) == 1) {
 178                 const struct lttng_ust_objd_ops *ops = objd_ops(id);
 179
 180                 if (ops->release)
 181                         ops->release(id);
 182                 objd_free(id);
 183         }
 184         return 0;
 185 }
 186
 187 static
 188 void objd_table_destroy(void)
 189 {
 190         int i;
 191
 192         for (i = 0; i < objd_table.allocated_len; i++)
 193                 (void) lttng_ust_objd_unref(i);
 194         free(objd_table.array);
 195         objd_table.array = NULL;
 196         objd_table.len = 0;
 197         objd_table.allocated_len = 0;
 198         objd_table.freelist_head = -1;
 199 }
 200
 201 /*
 202  * This is LTTng's own personal way to create an ABI for sessiond.
 203  * We send commands over a socket.
 204  */
 205
 206 static const struct lttng_ust_objd_ops lttng_ops;
 207 static const struct lttng_ust_objd_ops lttng_session_ops;
 208 static const struct lttng_ust_objd_ops lttng_channel_ops;
 209 static const struct lttng_ust_objd_ops lttng_metadata_ops;
 210 static const struct lttng_ust_objd_ops lttng_event_ops;
 211 static const struct lttng_ust_objd_ops lib_ring_buffer_objd_ops;
 212 static const struct lttng_ust_objd_ops lttng_tracepoint_list_ops;
 213
 214 enum channel_type {
 215         PER_CPU_CHANNEL,
 216         METADATA_CHANNEL,
 217 };
 218
 219 int lttng_abi_create_root_handle(void)
 220 {
 221         int root_handle;
 222
 223         root_handle = objd_alloc(NULL, &lttng_ops);
 224         return root_handle;
 225 }
 226
 227 static
 228 int lttng_abi_create_session(void)
 229 {
 230         struct ltt_session *session;
 231         int session_objd, ret;
 232
 233         session = ltt_session_create();
 234         if (!session)
 235                 return -ENOMEM;
 236         session_objd = objd_alloc(session, &lttng_session_ops);
 237         if (session_objd < 0) {
 238                 ret = session_objd;
 239                 goto objd_error;
 240         }
 241         session->objd = session_objd;
 242         return session_objd;
 243
 244 objd_error:
 245         ltt_session_destroy(session);
 246         return ret;
 247 }
 248
 249 static
 250 long lttng_abi_tracer_version(int objd,
 251         struct lttng_ust_tracer_version *v)
 252 {
 253         v->major = LTTNG_UST_MAJOR_VERSION;
 254         v->minor = LTTNG_UST_MINOR_VERSION;
 255         v->patchlevel = LTTNG_UST_PATCHLEVEL_VERSION;
 256         return 0;
 257 }
 258
 259 static
 260 long lttng_abi_add_context(int objd,
 261         struct lttng_ust_context *context_param,
 262         struct lttng_ctx **ctx, struct ltt_session *session)
 263 {
 264         if (session->been_active)
 265                 return -EPERM;
 266
 267         switch (context_param->ctx) {
 268         case LTTNG_UST_CONTEXT_PTHREAD_ID:
 269                 return lttng_add_pthread_id_to_ctx(ctx);
 270         case LTTNG_UST_CONTEXT_VTID:
 271                 return lttng_add_vtid_to_ctx(ctx);
 272         case LTTNG_UST_CONTEXT_VPID:
 273                 return lttng_add_vpid_to_ctx(ctx);
 274         case LTTNG_UST_CONTEXT_PROCNAME:
 275                 return lttng_add_procname_to_ctx(ctx);
 276         default:
 277                 return -EINVAL;
 278         }
 279 }
 280
 281 /**
 282  *      lttng_cmd - lttng control through socket commands
 283  *
 284  *      @objd: the object descriptor
 285  *      @cmd: the command
 286  *      @arg: command arg
 287  *
 288  *      This descriptor implements lttng commands:
 289  *      LTTNG_UST_SESSION
 290  *              Returns a LTTng trace session object descriptor
 291  *      LTTNG_UST_TRACER_VERSION
 292  *              Returns the LTTng kernel tracer version
 293  *      LTTNG_UST_TRACEPOINT_LIST
 294  *              Returns a file descriptor listing available tracepoints
 295  *      LTTNG_UST_WAIT_QUIESCENT
 296  *              Returns after all previously running probes have completed
 297  *
 298  * The returned session will be deleted when its file descriptor is closed.
 299  */
 300 static
 301 long lttng_cmd(int objd, unsigned int cmd, unsigned long arg)
 302 {
 303         switch (cmd) {
 304         case LTTNG_UST_SESSION:
 305                 return lttng_abi_create_session();
 306         case LTTNG_UST_TRACER_VERSION:
 307                 return lttng_abi_tracer_version(objd,
 308                                 (struct lttng_ust_tracer_version *) arg);
 309         case LTTNG_UST_TRACEPOINT_LIST:
 310                 return lttng_abi_tracepoint_list();
 311         case LTTNG_UST_WAIT_QUIESCENT:
 312                 synchronize_trace();
 313                 return 0;
 314         default:
 315                 return -EINVAL;
 316         }
 317 }
 318
 319 static const struct lttng_ust_objd_ops lttng_ops = {
 320         .cmd = lttng_cmd,
 321 };
 322
 323 /*
 324  * We tolerate no failure in this function (if one happens, we print a dmesg
 325  * error, but cannot return any error, because the channel information is
 326  * invariant.
 327  */
 328 static
 329 void lttng_metadata_create_events(int channel_objd)
 330 {
 331         struct ltt_channel *channel = objd_private(channel_objd);
 332         static struct lttng_ust_event metadata_params = {
 333                 .instrumentation = LTTNG_UST_TRACEPOINT,
 334                 .name = "lttng_ust:metadata",
 335         };
 336         struct ltt_event *event;
 337         int ret;
 338
 339         /*
 340          * We tolerate no failure path after event creation. It will stay
 341          * invariant for the rest of the session.
 342          */
 343         ret = ltt_event_create(channel, &metadata_params, NULL, &event);
 344         if (ret < 0) {
 345                 goto create_error;
 346         }
 347         return;
 348
 349 create_error:
 350         WARN_ON(1);
 351         return;         /* not allowed to return error */
 352 }
 353
 354 int lttng_abi_create_channel(int session_objd,
 355                              struct lttng_ust_channel *chan_param,
 356                              enum channel_type channel_type)
 357 {
 358         struct ltt_session *session = objd_private(session_objd);
 359         const struct lttng_ust_objd_ops *ops;
 360         const char *transport_name;
 361         struct ltt_channel *chan;
 362         int chan_objd;
 363         int ret = 0;
 364         struct ltt_channel chan_priv_init;
 365
 366         switch (channel_type) {
 367         case PER_CPU_CHANNEL:
 368                 if (chan_param->output == LTTNG_UST_MMAP) {
 369                         transport_name = chan_param->overwrite ?
 370                                 "relay-overwrite-mmap" : "relay-discard-mmap";
 371                 } else {
 372                         return -EINVAL;
 373                 }
 374                 ops = &lttng_channel_ops;
 375                 break;
 376         case METADATA_CHANNEL:
 377                 if (chan_param->output == LTTNG_UST_MMAP)
 378                         transport_name = "relay-metadata-mmap";
 379                 else
 380                         return -EINVAL;
 381                 ops = &lttng_metadata_ops;
 382                 break;
 383         default:
 384                 transport_name = "<unknown>";
 385                 return -EINVAL;
 386         }
 387         chan_objd = objd_alloc(NULL, ops);
 388         if (chan_objd < 0) {
 389                 ret = chan_objd;
 390                 goto objd_error;
 391         }
 392         memset(&chan_priv_init, 0, sizeof(chan_priv_init));
 393         /* Copy of session UUID for consumer (availability through shm) */
 394         memcpy(chan_priv_init.uuid, session->uuid, sizeof(session->uuid));
 395
 396         /*
 397          * We tolerate no failure path after channel creation. It will stay
 398          * invariant for the rest of the session.
 399          */
 400         chan = ltt_channel_create(session, transport_name, NULL,
 401                                   chan_param->subbuf_size,
 402                                   chan_param->num_subbuf,
 403                                   chan_param->switch_timer_interval,
 404                                   chan_param->read_timer_interval,
 405                                   &chan_param->shm_fd,
 406                                   &chan_param->wait_fd,
 407                                   &chan_param->memory_map_size,
 408                                   &chan_priv_init);
 409         if (!chan) {
 410                 ret = -EINVAL;
 411                 goto chan_error;
 412         }
 413         objd_set_private(chan_objd, chan);
 414         chan->objd = chan_objd;
 415         if (channel_type == METADATA_CHANNEL) {
 416                 session->metadata = chan;
 417                 lttng_metadata_create_events(chan_objd);
 418         }
 419         /* The channel created holds a reference on the session */
 420         objd_ref(session_objd);
 421
 422         return chan_objd;
 423
 424 chan_error:
 425         {
 426                 int err;
 427
 428                 err = lttng_ust_objd_unref(chan_objd);
 429                 assert(!err);
 430         }
 431 objd_error:
 432         return ret;
 433 }
 434
 435 /**
 436  *      lttng_session_cmd - lttng session object command
 437  *
 438  *      @obj: the object
 439  *      @cmd: the command
 440  *      @arg: command arg
 441  *
 442  *      This descriptor implements lttng commands:
 443  *      LTTNG_UST_CHANNEL
 444  *              Returns a LTTng channel object descriptor
 445  *      LTTNG_UST_ENABLE
 446  *              Enables tracing for a session (weak enable)
 447  *      LTTNG_UST_DISABLE
 448  *              Disables tracing for a session (strong disable)
 449  *      LTTNG_UST_METADATA
 450  *              Returns a LTTng metadata object descriptor
 451  *
 452  * The returned channel will be deleted when its file descriptor is closed.
 453  */
 454 static
 455 long lttng_session_cmd(int objd, unsigned int cmd, unsigned long arg)
 456 {
 457         struct ltt_session *session = objd_private(objd);
 458
 459         switch (cmd) {
 460         case LTTNG_UST_CHANNEL:
 461                 return lttng_abi_create_channel(objd,
 462                                 (struct lttng_ust_channel *) arg,
 463                                 PER_CPU_CHANNEL);
 464         case LTTNG_UST_SESSION_START:
 465         case LTTNG_UST_ENABLE:
 466                 return ltt_session_enable(session);
 467         case LTTNG_UST_SESSION_STOP:
 468         case LTTNG_UST_DISABLE:
 469                 return ltt_session_disable(session);
 470         case LTTNG_UST_METADATA:
 471                 return lttng_abi_create_channel(objd,
 472                                 (struct lttng_ust_channel *) arg,
 473                                 METADATA_CHANNEL);
 474         default:
 475                 return -EINVAL;
 476         }
 477 }
 478
 479 /*
 480  * Called when the last file reference is dropped.
 481  *
 482  * Big fat note: channels and events are invariant for the whole session after
 483  * their creation. So this session destruction also destroys all channel and
 484  * event structures specific to this session (they are not destroyed when their
 485  * individual file is released).
 486  */
 487 static
 488 int lttng_release_session(int objd)
 489 {
 490         struct ltt_session *session = objd_private(objd);
 491
 492         if (session) {
 493                 ltt_session_destroy(session);
 494                 return 0;
 495         } else {
 496                 return -EINVAL;
 497         }
 498 }
 499
 500 static const struct lttng_ust_objd_ops lttng_session_ops = {
 501         .release = lttng_release_session,
 502         .cmd = lttng_session_cmd,
 503 };
 504
 505 /*
 506  * beware: we don't keep the mutex over the send, but we must walk the
 507  * whole list each time we are called again. So sending one tracepoint
 508  * at a time means this is O(n^2). TODO: do as in the kernel and send
 509  * multiple tracepoints for each call to amortize this cost.
 510  */
 511 static
 512 void ltt_tracepoint_list_get(struct ltt_tracepoint_list *list,
 513                 char *tp_list_entry)
 514 {
 515 next:
 516         if (!list->got_first) {
 517                 tracepoint_iter_start(&list->iter);
 518                 list->got_first = 1;
 519                 goto copy;
 520         }
 521         tracepoint_iter_next(&list->iter);
 522 copy:
 523         if (!list->iter.tracepoint) {
 524                 tp_list_entry[0] = '\0';        /* end of list */
 525         } else {
 526                 if (!strcmp((*list->iter.tracepoint)->name,
 527                                 "lttng_ust:metadata"))
 528                         goto next;
 529                 memcpy(tp_list_entry, (*list->iter.tracepoint)->name,
 530                         LTTNG_UST_SYM_NAME_LEN);
 531         }
 532 }
 533
 534 static
 535 long lttng_tracepoint_list_cmd(int objd, unsigned int cmd, unsigned long arg)
 536 {
 537         struct ltt_tracepoint_list *list = objd_private(objd);
 538         char *str = (char *) arg;
 539
 540         switch (cmd) {
 541         case LTTNG_UST_TRACEPOINT_LIST_GET:
 542                 ltt_tracepoint_list_get(list, str);
 543                 if (str[0] == '\0')
 544                         return -ENOENT;
 545                 return 0;
 546         default:
 547                 return -EINVAL;
 548         }
 549 }
 550
 551 static
 552 int lttng_abi_tracepoint_list(void)
 553 {
 554         int list_objd, ret;
 555         struct ltt_tracepoint_list *list;
 556
 557         list_objd = objd_alloc(NULL, &lttng_tracepoint_list_ops);
 558         if (list_objd < 0) {
 559                 ret = list_objd;
 560                 goto objd_error;
 561         }
 562         list = zmalloc(sizeof(*list));
 563         if (!list) {
 564                 ret = -ENOMEM;
 565                 goto alloc_error;
 566         }
 567         objd_set_private(list_objd, list);
 568
 569         return list_objd;
 570
 571 alloc_error:
 572         {
 573                 int err;
 574
 575                 err = lttng_ust_objd_unref(list_objd);
 576                 assert(!err);
 577         }
 578 objd_error:
 579         return ret;
 580 }
 581
 582 static
 583 int lttng_release_tracepoint_list(int objd)
 584 {
 585         struct ltt_tracepoint_list *list = objd_private(objd);
 586
 587         if (list) {
 588                 tracepoint_iter_stop(&list->iter);
 589                 free(list);
 590                 return 0;
 591         } else {
 592                 return -EINVAL;
 593         }
 594 }
 595
 596 static const struct lttng_ust_objd_ops lttng_tracepoint_list_ops = {
 597         .release = lttng_release_tracepoint_list,
 598         .cmd = lttng_tracepoint_list_cmd,
 599 };
 600
 601 struct stream_priv_data {
 602         struct lttng_ust_lib_ring_buffer *buf;
 603         struct ltt_channel *ltt_chan;
 604 };
 605
 606 static
 607 int lttng_abi_open_stream(int channel_objd, struct lttng_ust_stream *info)
 608 {
 609         struct ltt_channel *channel = objd_private(channel_objd);
 610         struct lttng_ust_lib_ring_buffer *buf;
 611         struct stream_priv_data *priv;
 612         int stream_objd, ret;
 613
 614         buf = channel->ops->buffer_read_open(channel->chan, channel->handle,
 615                         &info->shm_fd, &info->wait_fd, &info->memory_map_size);
 616         if (!buf)
 617                 return -ENOENT;
 618
 619         priv = zmalloc(sizeof(*priv));
 620         if (!priv) {
 621                 ret = -ENOMEM;
 622                 goto alloc_error;
 623         }
 624         priv->buf = buf;
 625         priv->ltt_chan = channel;
 626         stream_objd = objd_alloc(priv, &lib_ring_buffer_objd_ops);
 627         if (stream_objd < 0) {
 628                 ret = stream_objd;
 629                 goto objd_error;
 630         }
 631         /* Hold a reference on the channel object descriptor */
 632         objd_ref(channel_objd);
 633         return stream_objd;
 634
 635 objd_error:
 636         free(priv);
 637 alloc_error:
 638         channel->ops->buffer_read_close(buf, channel->handle);
 639         return ret;
 640 }
 641
 642 static
 643 int lttng_abi_create_event(int channel_objd,
 644                            struct lttng_ust_event *event_param)
 645 {
 646         struct ltt_channel *channel = objd_private(channel_objd);
 647         struct ltt_event *event;
 648         int event_objd, ret;
 649
 650         event_param->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 651         event_objd = objd_alloc(NULL, &lttng_event_ops);
 652         if (event_objd < 0) {
 653                 ret = event_objd;
 654                 goto objd_error;
 655         }
 656         /*
 657          * We tolerate no failure path after event creation. It will stay
 658          * invariant for the rest of the session.
 659          */
 660         ret = ltt_event_create(channel, event_param, NULL, &event);
 661         if (ret < 0) {
 662                 goto event_error;
 663         }
 664         objd_set_private(event_objd, event);
 665         /* The event holds a reference on the channel */
 666         objd_ref(channel_objd);
 667         return event_objd;
 668
 669 event_error:
 670         {
 671                 int err;
 672
 673                 err = lttng_ust_objd_unref(event_objd);
 674                 assert(!err);
 675         }
 676 objd_error:
 677         return ret;
 678 }
 679
 680 /**
 681  *      lttng_channel_cmd - lttng control through object descriptors
 682  *
 683  *      @objd: the object descriptor
 684  *      @cmd: the command
 685  *      @arg: command arg
 686  *
 687  *      This object descriptor implements lttng commands:
 688  *      LTTNG_UST_STREAM
 689  *              Returns an event stream object descriptor or failure.
 690  *              (typically, one event stream records events from one CPU)
 691  *      LTTNG_UST_EVENT
 692  *              Returns an event object descriptor or failure.
 693  *      LTTNG_UST_CONTEXT
 694  *              Prepend a context field to each event in the channel
 695  *      LTTNG_UST_ENABLE
 696  *              Enable recording for events in this channel (weak enable)
 697  *      LTTNG_UST_DISABLE
 698  *              Disable recording for events in this channel (strong disable)
 699  *
 700  * Channel and event file descriptors also hold a reference on the session.
 701  */
 702 static
 703 long lttng_channel_cmd(int objd, unsigned int cmd, unsigned long arg)
 704 {
 705         struct ltt_channel *channel = objd_private(objd);
 706
 707         switch (cmd) {
 708         case LTTNG_UST_STREAM:
 709         {
 710                 struct lttng_ust_stream *stream;
 711
 712                 stream = (struct lttng_ust_stream *) arg;
 713                 /* stream used as output */
 714                 return lttng_abi_open_stream(objd, stream);
 715         }
 716         case LTTNG_UST_EVENT:
 717                 return lttng_abi_create_event(objd, (struct lttng_ust_event *) arg);
 718         case LTTNG_UST_CONTEXT:
 719                 return lttng_abi_add_context(objd,
 720                                 (struct lttng_ust_context *) arg,
 721                                 &channel->ctx, channel->session);
 722         case LTTNG_UST_ENABLE:
 723                 return ltt_channel_enable(channel);
 724         case LTTNG_UST_DISABLE:
 725                 return ltt_channel_disable(channel);
 726         case LTTNG_UST_FLUSH_BUFFER:
 727                 return channel->ops->flush_buffer(channel->chan, channel->handle);
 728         default:
 729                 return -EINVAL;
 730         }
 731 }
 732
 733 /**
 734  *      lttng_metadata_cmd - lttng control through object descriptors
 735  *
 736  *      @objd: the object descriptor
 737  *      @cmd: the command
 738  *      @arg: command arg
 739  *
 740  *      This object descriptor implements lttng commands:
 741  *      LTTNG_UST_STREAM
 742  *              Returns an event stream file descriptor or failure.
 743  *
 744  * Channel and event file descriptors also hold a reference on the session.
 745  */
 746 static
 747 long lttng_metadata_cmd(int objd, unsigned int cmd, unsigned long arg)
 748 {
 749         struct ltt_channel *channel = objd_private(objd);
 750
 751         switch (cmd) {
 752         case LTTNG_UST_STREAM:
 753         {
 754                 struct lttng_ust_stream *stream;
 755
 756                 stream = (struct lttng_ust_stream *) arg;
 757                 /* stream used as output */
 758                 return lttng_abi_open_stream(objd, stream);
 759         }
 760         case LTTNG_UST_FLUSH_BUFFER:
 761                 return channel->ops->flush_buffer(channel->chan, channel->handle);
 762         default:
 763                 return -EINVAL;
 764         }
 765 }
 766
 767 #if 0
 768 /**
 769  *      lttng_channel_poll - lttng stream addition/removal monitoring
 770  *
 771  *      @file: the file
 772  *      @wait: poll table
 773  */
 774 unsigned int lttng_channel_poll(struct file *file, poll_table *wait)
 775 {
 776         struct ltt_channel *channel = file->private_data;
 777         unsigned int mask = 0;
 778
 779         if (file->f_mode & FMODE_READ) {
 780                 poll_wait_set_exclusive(wait);
 781                 poll_wait(file, channel->ops->get_hp_wait_queue(channel->chan),
 782                           wait);
 783
 784                 if (channel->ops->is_disabled(channel->chan))
 785                         return POLLERR;
 786                 if (channel->ops->is_finalized(channel->chan))
 787                         return POLLHUP;
 788                 if (channel->ops->buffer_has_read_closed_stream(channel->chan))
 789                         return POLLIN | POLLRDNORM;
 790                 return 0;
 791         }
 792         return mask;
 793
 794 }
 795 #endif //0
 796
 797 static
 798 int lttng_channel_release(int objd)
 799 {
 800         struct ltt_channel *channel = objd_private(objd);
 801
 802         if (channel)
 803                 return lttng_ust_objd_unref(channel->session->objd);
 804         return 0;
 805 }
 806
 807 static const struct lttng_ust_objd_ops lttng_channel_ops = {
 808         .release = lttng_channel_release,
 809         //.poll = lttng_channel_poll,
 810         .cmd = lttng_channel_cmd,
 811 };
 812
 813 static const struct lttng_ust_objd_ops lttng_metadata_ops = {
 814         .release = lttng_channel_release,
 815         .cmd = lttng_metadata_cmd,
 816 };
 817
 818 /**
 819  *      lttng_rb_cmd - lttng ring buffer control through object descriptors
 820  *
 821  *      @objd: the object descriptor
 822  *      @cmd: the command
 823  *      @arg: command arg
 824  *
 825  *      This object descriptor implements lttng commands:
 826  *              (None for now. Access is done directly though shm.)
 827  */
 828 static
 829 long lttng_rb_cmd(int objd, unsigned int cmd, unsigned long arg)
 830 {
 831         switch (cmd) {
 832         default:
 833                 return -EINVAL;
 834         }
 835 }
 836
 837 static
 838 int lttng_rb_release(int objd)
 839 {
 840         struct stream_priv_data *priv = objd_private(objd);
 841         struct lttng_ust_lib_ring_buffer *buf;
 842         struct ltt_channel *channel;
 843
 844         if (priv) {
 845                 buf = priv->buf;
 846                 channel = priv->ltt_chan;
 847                 free(priv);
 848                 /*
 849                  * If we are at ABI exit, we don't want to close the
 850                  * buffer opened for read: it is being shared between
 851                  * the parent and child (right after fork), and we don't
 852                  * want the child to close it for the parent. For a real
 853                  * exit, we don't care about marking it as closed, as
 854                  * the consumer daemon (if there is one) will do fine
 855                  * even if we don't mark it as "closed" for reading on
 856                  * our side.
 857                  * We only mark it as closed if it is being explicitely
 858                  * released by the session daemon with an explicit
 859                  * release command.
 860                  */
 861                 if (!lttng_ust_abi_close_in_progress)
 862                         channel->ops->buffer_read_close(buf, channel->handle);
 863
 864                 return lttng_ust_objd_unref(channel->objd);
 865         }
 866         return 0;
 867 }
 868
 869 static const struct lttng_ust_objd_ops lib_ring_buffer_objd_ops = {
 870         .release = lttng_rb_release,
 871         .cmd = lttng_rb_cmd,
 872 };
 873
 874 /**
 875  *      lttng_event_cmd - lttng control through object descriptors
 876  *
 877  *      @objd: the object descriptor
 878  *      @cmd: the command
 879  *      @arg: command arg
 880  *
 881  *      This object descriptor implements lttng commands:
 882  *      LTTNG_UST_CONTEXT
 883  *              Prepend a context field to each record of this event
 884  *      LTTNG_UST_ENABLE
 885  *              Enable recording for this event (weak enable)
 886  *      LTTNG_UST_DISABLE
 887  *              Disable recording for this event (strong disable)
 888  */
 889 static
 890 long lttng_event_cmd(int objd, unsigned int cmd, unsigned long arg)
 891 {
 892         struct ltt_event *event = objd_private(objd);
 893
 894         switch (cmd) {
 895         case LTTNG_UST_CONTEXT:
 896                 return lttng_abi_add_context(objd,
 897                                 (struct lttng_ust_context *) arg,
 898                                 &event->ctx, event->chan->session);
 899         case LTTNG_UST_ENABLE:
 900                 return ltt_event_enable(event);
 901         case LTTNG_UST_DISABLE:
 902                 return ltt_event_disable(event);
 903         default:
 904                 return -EINVAL;
 905         }
 906 }
 907
 908 static
 909 int lttng_event_release(int objd)
 910 {
 911         struct ltt_event *event = objd_private(objd);
 912
 913         if (event)
 914                 return lttng_ust_objd_unref(event->chan->objd);
 915         return 0;
 916 }
 917
 918 /* TODO: filter control ioctl */
 919 static const struct lttng_ust_objd_ops lttng_event_ops = {
 920         .release = lttng_event_release,
 921         .cmd = lttng_event_cmd,
 922 };
 923
 924 void lttng_ust_abi_exit(void)
 925 {
 926         lttng_ust_abi_close_in_progress = 1;
 927         objd_table_destroy();
 928         lttng_ust_abi_close_in_progress = 0;
 929 }