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