liblttng-ust/lttng-ust-abi.c

   1 /*
   2  * lttng-ust-abi.c
   3  *
   4  * LTTng UST ABI
   5  *
   6  * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  *
  22  *
  23  * Mimic system calls for:
  24  * - session creation, returns an object descriptor or failure.
  25  *   - channel creation, returns an object descriptor or failure.
  26  *     - Operates on a session object descriptor
  27  *     - Takes all channel options as parameters.
  28  *   - stream get, returns an object descriptor or failure.
  29  *     - Operates on a channel object descriptor.
  30  *   - stream notifier get, returns an object descriptor or failure.
  31  *     - Operates on a channel object descriptor.
  32  *   - event creation, returns an object descriptor or failure.
  33  *     - Operates on a channel object descriptor
  34  *     - Takes an event name as parameter
  35  *     - Takes an instrumentation source as parameter
  36  *       - e.g. tracepoints, dynamic_probes...
  37  *     - Takes instrumentation source specific arguments.
  38  */
  39
  40 #include <lttng/ust-abi.h>
  41 #include <lttng/ust-error.h>
  42 #include <urcu/compiler.h>
  43 #include <urcu/list.h>
  44 #include <lttng/ust-events.h>
  45 #include <lttng/ust-version.h>
  46 #include <lttng/tracepoint.h>
  47 #include "tracepoint-internal.h"
  48 #include <usterr-signal-safe.h>
  49 #include <helper.h>
  50 #include "lttng-tracer.h"
  51 #include "../libringbuffer/shm.h"
  52 #include "../libringbuffer/frontend_types.h"
  53
  54 #define OBJ_NAME_LEN    16
  55
  56 static int lttng_ust_abi_close_in_progress;
  57
  58 static
  59 int lttng_abi_tracepoint_list(void *owner);
  60 static
  61 int lttng_abi_tracepoint_field_list(void *owner);
  62
  63 /*
  64  * Object descriptor table. Should be protected from concurrent access
  65  * by the caller.
  66  */
  67
  68 struct lttng_ust_obj {
  69         union {
  70                 struct {
  71                         void *private_data;
  72                         const struct lttng_ust_objd_ops *ops;
  73                         int f_count;
  74                         void *owner;
  75                         char name[OBJ_NAME_LEN];
  76                 } s;
  77                 int freelist_next;      /* offset freelist. end is -1. */
  78         } u;
  79 };
  80
  81 struct lttng_ust_objd_table {
  82         struct lttng_ust_obj *array;
  83         unsigned int len, allocated_len;
  84         int freelist_head;              /* offset freelist head. end is -1 */
  85 };
  86
  87 static struct lttng_ust_objd_table objd_table = {
  88         .freelist_head = -1,
  89 };
  90
  91 static
  92 int objd_alloc(void *private_data, const struct lttng_ust_objd_ops *ops,
  93                 void *owner, const char *name)
  94 {
  95         struct lttng_ust_obj *obj;
  96
  97         if (objd_table.freelist_head != -1) {
  98                 obj = &objd_table.array[objd_table.freelist_head];
  99                 objd_table.freelist_head = obj->u.freelist_next;
 100                 goto end;
 101         }
 102
 103         if (objd_table.len >= objd_table.allocated_len) {
 104                 unsigned int new_allocated_len, old_allocated_len;
 105                 struct lttng_ust_obj *new_table, *old_table;
 106
 107                 old_allocated_len = objd_table.allocated_len;
 108                 old_table = objd_table.array;
 109                 if (!old_allocated_len)
 110                         new_allocated_len = 1;
 111                 else
 112                         new_allocated_len = old_allocated_len << 1;
 113                 new_table = zmalloc(sizeof(struct lttng_ust_obj) * new_allocated_len);
 114                 if (!new_table)
 115                         return -ENOMEM;
 116                 memcpy(new_table, old_table,
 117                        sizeof(struct lttng_ust_obj) * old_allocated_len);
 118                 free(old_table);
 119                 objd_table.array = new_table;
 120                 objd_table.allocated_len = new_allocated_len;
 121         }
 122         obj = &objd_table.array[objd_table.len];
 123         objd_table.len++;
 124 end:
 125         obj->u.s.private_data = private_data;
 126         obj->u.s.ops = ops;
 127         obj->u.s.f_count = 2;   /* count == 1 : object is allocated */
 128                                 /* count == 2 : allocated + hold ref */
 129         obj->u.s.owner = owner;
 130         strncpy(obj->u.s.name, name, OBJ_NAME_LEN);
 131         obj->u.s.name[OBJ_NAME_LEN - 1] = '\0';
 132         return obj - objd_table.array;
 133 }
 134
 135 static
 136 struct lttng_ust_obj *_objd_get(int id)
 137 {
 138         if (id >= objd_table.len)
 139                 return NULL;
 140         if (!objd_table.array[id].u.s.f_count)
 141                 return NULL;
 142         return &objd_table.array[id];
 143 }
 144
 145 static
 146 void *objd_private(int id)
 147 {
 148         struct lttng_ust_obj *obj = _objd_get(id);
 149         assert(obj);
 150         return obj->u.s.private_data;
 151 }
 152
 153 static
 154 void objd_set_private(int id, void *private_data)
 155 {
 156         struct lttng_ust_obj *obj = _objd_get(id);
 157         assert(obj);
 158         obj->u.s.private_data = private_data;
 159 }
 160
 161 const struct lttng_ust_objd_ops *objd_ops(int id)
 162 {
 163         struct lttng_ust_obj *obj = _objd_get(id);
 164
 165         if (!obj)
 166                 return NULL;
 167         return obj->u.s.ops;
 168 }
 169
 170 static
 171 void objd_free(int id)
 172 {
 173         struct lttng_ust_obj *obj = _objd_get(id);
 174
 175         assert(obj);
 176         obj->u.freelist_next = objd_table.freelist_head;
 177         objd_table.freelist_head = obj - objd_table.array;
 178         assert(obj->u.s.f_count == 1);
 179         obj->u.s.f_count = 0;   /* deallocated */
 180 }
 181
 182 static
 183 void objd_ref(int id)
 184 {
 185         struct lttng_ust_obj *obj = _objd_get(id);
 186         obj->u.s.f_count++;
 187 }
 188
 189 int lttng_ust_objd_unref(int id)
 190 {
 191         struct lttng_ust_obj *obj = _objd_get(id);
 192
 193         if (!obj)
 194                 return -EINVAL;
 195         if (obj->u.s.f_count == 1) {
 196                 ERR("Reference counting error\n");
 197                 return -EINVAL;
 198         }
 199         if ((--obj->u.s.f_count) == 1) {
 200                 const struct lttng_ust_objd_ops *ops = objd_ops(id);
 201
 202                 if (ops->release)
 203                         ops->release(id);
 204                 objd_free(id);
 205         }
 206         return 0;
 207 }
 208
 209 static
 210 void objd_table_destroy(void)
 211 {
 212         int i;
 213
 214         for (i = 0; i < objd_table.allocated_len; i++)
 215                 (void) lttng_ust_objd_unref(i);
 216         free(objd_table.array);
 217         objd_table.array = NULL;
 218         objd_table.len = 0;
 219         objd_table.allocated_len = 0;
 220         objd_table.freelist_head = -1;
 221 }
 222
 223 const char *lttng_ust_obj_get_name(int id)
 224 {
 225         struct lttng_ust_obj *obj = _objd_get(id);
 226
 227         if (!obj)
 228                 return NULL;
 229         return obj->u.s.name;
 230 }
 231
 232 void lttng_ust_objd_table_owner_cleanup(void *owner)
 233 {
 234         int i;
 235
 236         for (i = 0; i < objd_table.allocated_len; i++) {
 237                 struct lttng_ust_obj *obj;
 238
 239                 obj = _objd_get(i);
 240                 if (!obj)
 241                         continue;
 242                 if (!obj->u.s.owner)
 243                         continue;       /* skip root handles */
 244                 if (obj->u.s.owner == owner)
 245                         (void) lttng_ust_objd_unref(i);
 246         }
 247 }
 248
 249 /*
 250  * This is LTTng's own personal way to create an ABI for sessiond.
 251  * We send commands over a socket.
 252  */
 253
 254 static const struct lttng_ust_objd_ops lttng_ops;
 255 static const struct lttng_ust_objd_ops lttng_session_ops;
 256 static const struct lttng_ust_objd_ops lttng_channel_ops;
 257 static const struct lttng_ust_objd_ops lttng_enabler_ops;
 258 static const struct lttng_ust_objd_ops lttng_tracepoint_list_ops;
 259 static const struct lttng_ust_objd_ops lttng_tracepoint_field_list_ops;
 260
 261 int lttng_abi_create_root_handle(void)
 262 {
 263         int root_handle;
 264
 265         /* root handles have NULL owners */
 266         root_handle = objd_alloc(NULL, &lttng_ops, NULL, "root");
 267         return root_handle;
 268 }
 269
 270 static
 271 int lttng_is_channel_ready(struct lttng_channel *lttng_chan)
 272 {
 273         struct channel *chan;
 274         unsigned int nr_streams, exp_streams;
 275
 276         chan = lttng_chan->chan;
 277         nr_streams = channel_handle_get_nr_streams(lttng_chan->handle);
 278         exp_streams = chan->nr_streams;
 279         return nr_streams == exp_streams;
 280 }
 281
 282 static
 283 int lttng_abi_create_session(void *owner)
 284 {
 285         struct lttng_session *session;
 286         int session_objd, ret;
 287
 288         session = lttng_session_create();
 289         if (!session)
 290                 return -ENOMEM;
 291         session_objd = objd_alloc(session, &lttng_session_ops, owner, "session");
 292         if (session_objd < 0) {
 293                 ret = session_objd;
 294                 goto objd_error;
 295         }
 296         session->objd = session_objd;
 297         session->owner = owner;
 298         return session_objd;
 299
 300 objd_error:
 301         lttng_session_destroy(session);
 302         return ret;
 303 }
 304
 305 static
 306 long lttng_abi_tracer_version(int objd,
 307         struct lttng_ust_tracer_version *v)
 308 {
 309         v->major = LTTNG_UST_MAJOR_VERSION;
 310         v->minor = LTTNG_UST_MINOR_VERSION;
 311         v->patchlevel = LTTNG_UST_PATCHLEVEL_VERSION;
 312         return 0;
 313 }
 314
 315 static
 316 long lttng_abi_add_context(int objd,
 317         struct lttng_ust_context *context_param,
 318         struct lttng_ctx **ctx, struct lttng_session *session)
 319 {
 320         return lttng_attach_context(context_param, ctx, session);
 321 }
 322
 323 /**
 324  *      lttng_cmd - lttng control through socket commands
 325  *
 326  *      @objd: the object descriptor
 327  *      @cmd: the command
 328  *      @arg: command arg
 329  *      @uargs: UST arguments (internal)
 330  *      @owner: objd owner
 331  *
 332  *      This descriptor implements lttng commands:
 333  *      LTTNG_UST_SESSION
 334  *              Returns a LTTng trace session object descriptor
 335  *      LTTNG_UST_TRACER_VERSION
 336  *              Returns the LTTng kernel tracer version
 337  *      LTTNG_UST_TRACEPOINT_LIST
 338  *              Returns a file descriptor listing available tracepoints
 339  *      LTTNG_UST_TRACEPOINT_FIELD_LIST
 340  *              Returns a file descriptor listing available tracepoint fields
 341  *      LTTNG_UST_WAIT_QUIESCENT
 342  *              Returns after all previously running probes have completed
 343  *
 344  * The returned session will be deleted when its file descriptor is closed.
 345  */
 346 static
 347 long lttng_cmd(int objd, unsigned int cmd, unsigned long arg,
 348         union ust_args *uargs, void *owner)
 349 {
 350         switch (cmd) {
 351         case LTTNG_UST_SESSION:
 352                 return lttng_abi_create_session(owner);
 353         case LTTNG_UST_TRACER_VERSION:
 354                 return lttng_abi_tracer_version(objd,
 355                                 (struct lttng_ust_tracer_version *) arg);
 356         case LTTNG_UST_TRACEPOINT_LIST:
 357                 return lttng_abi_tracepoint_list(owner);
 358         case LTTNG_UST_TRACEPOINT_FIELD_LIST:
 359                 return lttng_abi_tracepoint_field_list(owner);
 360         case LTTNG_UST_WAIT_QUIESCENT:
 361                 synchronize_trace();
 362                 return 0;
 363         default:
 364                 return -EINVAL;
 365         }
 366 }
 367
 368 static const struct lttng_ust_objd_ops lttng_ops = {
 369         .cmd = lttng_cmd,
 370 };
 371
 372 /*
 373  * We tolerate no failure in this function (if one happens, we print a dmesg
 374  * error, but cannot return any error, because the channel information is
 375  * invariant.
 376  */
 377 static
 378 void lttng_metadata_create_events(int channel_objd)
 379 {
 380         struct lttng_channel *chan = objd_private(channel_objd);
 381         struct lttng_enabler *enabler;
 382         static struct lttng_ust_event metadata_params = {
 383                 .instrumentation = LTTNG_UST_TRACEPOINT,
 384                 .name = "lttng_ust:metadata",
 385                 .loglevel_type = LTTNG_UST_LOGLEVEL_ALL,
 386                 .loglevel = TRACE_DEFAULT,
 387         };
 388
 389         /*
 390          * We tolerate no failure path after event creation. It will stay
 391          * invariant for the rest of the session.
 392          */
 393         enabler = lttng_enabler_create(LTTNG_ENABLER_EVENT,
 394                                 &metadata_params, chan);
 395         if (!enabler) {
 396                 goto create_error;
 397         }
 398         return;
 399
 400 create_error:
 401         WARN_ON(1);
 402         return;         /* not allowed to return error */
 403 }
 404
 405 int lttng_abi_map_channel(int session_objd,
 406                 struct lttng_ust_channel *ust_chan,
 407                 union ust_args *uargs,
 408                 void *owner)
 409 {
 410         struct lttng_session *session = objd_private(session_objd);
 411         const char *transport_name;
 412         const struct lttng_transport *transport;
 413         const char *chan_name;
 414         int chan_objd;
 415         struct lttng_ust_shm_handle *channel_handle;
 416         struct lttng_channel *lttng_chan;
 417         struct channel *chan;
 418         struct lttng_ust_lib_ring_buffer_config *config;
 419         void *chan_data;
 420         uint64_t len;
 421         int ret;
 422         enum lttng_ust_chan_type type;
 423
 424         chan_data = uargs->channel.chan_data;
 425         len = ust_chan->len;
 426         type = ust_chan->type;
 427
 428         switch (type) {
 429         case LTTNG_UST_CHAN_PER_CPU:
 430         case LTTNG_UST_CHAN_METADATA:
 431                 break;
 432         default:
 433                 return -EINVAL;
 434         }
 435
 436         if (session->been_active) {
 437                 ret = -EBUSY;
 438                 goto active;    /* Refuse to add channel to active session */
 439         }
 440
 441         channel_handle = channel_handle_create(chan_data, len);
 442         if (!channel_handle) {
 443                 ret = -EINVAL;
 444                 goto handle_error;
 445         }
 446
 447         chan = shmp(channel_handle, channel_handle->chan);
 448         assert(chan);
 449         config = &chan->backend.config;
 450         lttng_chan = channel_get_private(chan);
 451         if (!lttng_chan) {
 452                 ret = -EINVAL;
 453                 goto alloc_error;
 454         }
 455
 456         /* Lookup transport name */
 457         switch (type) {
 458         case LTTNG_UST_CHAN_PER_CPU:
 459                 if (config->output == RING_BUFFER_MMAP) {
 460                         transport_name = config->mode == RING_BUFFER_OVERWRITE ?
 461                                 "relay-overwrite-mmap" : "relay-discard-mmap";
 462                 } else {
 463                         ret = -EINVAL;
 464                         goto notransport;
 465                 }
 466                 chan_name = "channel";
 467                 break;
 468         case LTTNG_UST_CHAN_METADATA:
 469                 if (config->output == RING_BUFFER_MMAP) {
 470                         transport_name = "relay-metadata-mmap";
 471                 } else {
 472                         ret = -EINVAL;
 473                         goto notransport;
 474                 }
 475                 chan_name = "metadata";
 476                 break;
 477         default:
 478                 transport_name = "<unknown>";
 479                 chan_name = "<unknown>";
 480                 ret = -EINVAL;
 481                 goto notransport;
 482         }
 483         transport = lttng_transport_find(transport_name);
 484         if (!transport) {
 485                 DBG("LTTng transport %s not found\n",
 486                        transport_name);
 487                 ret = -EINVAL;
 488                 goto notransport;
 489         }
 490
 491         chan_objd = objd_alloc(NULL, &lttng_channel_ops, owner, chan_name);
 492         if (chan_objd < 0) {
 493                 ret = chan_objd;
 494                 goto objd_error;
 495         }
 496
 497         /* Initialize our lttng chan */
 498         lttng_chan->chan = chan;
 499         lttng_chan->enabled = 1;
 500         lttng_chan->ctx = NULL;
 501         lttng_chan->session = session;
 502         lttng_chan->ops = &transport->ops;
 503         memcpy(&lttng_chan->chan->backend.config,
 504                 transport->client_config,
 505                 sizeof(lttng_chan->chan->backend.config));
 506         cds_list_add(&lttng_chan->node, &session->chan_head);
 507         lttng_chan->header_type = 0;
 508         lttng_chan->handle = channel_handle;
 509         lttng_chan->metadata_dumped = 0;
 510         lttng_chan->type = type;
 511
 512         /*
 513          * We tolerate no failure path after channel creation. It will stay
 514          * invariant for the rest of the session.
 515          */
 516         objd_set_private(chan_objd, lttng_chan);
 517         lttng_chan->objd = chan_objd;
 518         /* The channel created holds a reference on the session */
 519         objd_ref(session_objd);
 520         return chan_objd;
 521
 522 objd_error:
 523 notransport:
 524         free(lttng_chan);
 525 alloc_error:
 526         channel_destroy(chan, channel_handle, 0);
 527 handle_error:
 528 active:
 529         return ret;
 530 }
 531
 532 /**
 533  *      lttng_session_cmd - lttng session object command
 534  *
 535  *      @obj: the object
 536  *      @cmd: the command
 537  *      @arg: command arg
 538  *      @uargs: UST arguments (internal)
 539  *      @owner: objd owner
 540  *
 541  *      This descriptor implements lttng commands:
 542  *      LTTNG_UST_CHANNEL
 543  *              Returns a LTTng channel object descriptor
 544  *      LTTNG_UST_ENABLE
 545  *              Enables tracing for a session (weak enable)
 546  *      LTTNG_UST_DISABLE
 547  *              Disables tracing for a session (strong disable)
 548  *      LTTNG_UST_METADATA
 549  *              Returns a LTTng metadata object descriptor
 550  *
 551  * The returned channel will be deleted when its file descriptor is closed.
 552  */
 553 static
 554 long lttng_session_cmd(int objd, unsigned int cmd, unsigned long arg,
 555         union ust_args *uargs, void *owner)
 556 {
 557         struct lttng_session *session = objd_private(objd);
 558
 559         switch (cmd) {
 560         case LTTNG_UST_CHANNEL:
 561                 return lttng_abi_map_channel(objd,
 562                                 (struct lttng_ust_channel *) arg,
 563                                 uargs, owner);
 564         case LTTNG_UST_SESSION_START:
 565         case LTTNG_UST_ENABLE:
 566                 return lttng_session_enable(session);
 567         case LTTNG_UST_SESSION_STOP:
 568         case LTTNG_UST_DISABLE:
 569                 return lttng_session_disable(session);
 570         default:
 571                 return -EINVAL;
 572         }
 573 }
 574
 575 /*
 576  * Called when the last file reference is dropped.
 577  *
 578  * Big fat note: channels and events are invariant for the whole session after
 579  * their creation. So this session destruction also destroys all channel and
 580  * event structures specific to this session (they are not destroyed when their
 581  * individual file is released).
 582  */
 583 static
 584 int lttng_release_session(int objd)
 585 {
 586         struct lttng_session *session = objd_private(objd);
 587
 588         if (session) {
 589                 lttng_session_destroy(session);
 590                 return 0;
 591         } else {
 592                 return -EINVAL;
 593         }
 594 }
 595
 596 static const struct lttng_ust_objd_ops lttng_session_ops = {
 597         .release = lttng_release_session,
 598         .cmd = lttng_session_cmd,
 599 };
 600
 601 static
 602 long lttng_tracepoint_list_cmd(int objd, unsigned int cmd, unsigned long arg,
 603         union ust_args *uargs, void *owner)
 604 {
 605         struct lttng_ust_tracepoint_list *list = objd_private(objd);
 606         struct lttng_ust_tracepoint_iter *tp =
 607                 (struct lttng_ust_tracepoint_iter *) arg;
 608         struct lttng_ust_tracepoint_iter *iter;
 609
 610         switch (cmd) {
 611         case LTTNG_UST_TRACEPOINT_LIST_GET:
 612         {
 613         retry:
 614                 iter = lttng_ust_tracepoint_list_get_iter_next(list);
 615                 if (!iter)
 616                         return -LTTNG_UST_ERR_NOENT;
 617                 if (!strcmp(iter->name, "lttng_ust:metadata"))
 618                         goto retry;
 619                 memcpy(tp, iter, sizeof(*tp));
 620                 return 0;
 621         }
 622         default:
 623                 return -EINVAL;
 624         }
 625 }
 626
 627 static
 628 int lttng_abi_tracepoint_list(void *owner)
 629 {
 630         int list_objd, ret;
 631         struct lttng_ust_tracepoint_list *list;
 632
 633         list_objd = objd_alloc(NULL, &lttng_tracepoint_list_ops, owner, "tp_list");
 634         if (list_objd < 0) {
 635                 ret = list_objd;
 636                 goto objd_error;
 637         }
 638         list = zmalloc(sizeof(*list));
 639         if (!list) {
 640                 ret = -ENOMEM;
 641                 goto alloc_error;
 642         }
 643         objd_set_private(list_objd, list);
 644
 645         /* populate list by walking on all registered probes. */
 646         ret = lttng_probes_get_event_list(list);
 647         if (ret) {
 648                 goto list_error;
 649         }
 650         return list_objd;
 651
 652 list_error:
 653         free(list);
 654 alloc_error:
 655         {
 656                 int err;
 657
 658                 err = lttng_ust_objd_unref(list_objd);
 659                 assert(!err);
 660         }
 661 objd_error:
 662         return ret;
 663 }
 664
 665 static
 666 int lttng_release_tracepoint_list(int objd)
 667 {
 668         struct lttng_ust_tracepoint_list *list = objd_private(objd);
 669
 670         if (list) {
 671                 lttng_probes_prune_event_list(list);
 672                 free(list);
 673                 return 0;
 674         } else {
 675                 return -EINVAL;
 676         }
 677 }
 678
 679 static const struct lttng_ust_objd_ops lttng_tracepoint_list_ops = {
 680         .release = lttng_release_tracepoint_list,
 681         .cmd = lttng_tracepoint_list_cmd,
 682 };
 683
 684 static
 685 long lttng_tracepoint_field_list_cmd(int objd, unsigned int cmd,
 686         unsigned long arg, union ust_args *uargs, void *owner)
 687 {
 688         struct lttng_ust_field_list *list = objd_private(objd);
 689         struct lttng_ust_field_iter *tp = &uargs->field_list.entry;
 690         struct lttng_ust_field_iter *iter;
 691
 692         switch (cmd) {
 693         case LTTNG_UST_TRACEPOINT_FIELD_LIST_GET:
 694         {
 695         retry:
 696                 iter = lttng_ust_field_list_get_iter_next(list);
 697                 if (!iter)
 698                         return -LTTNG_UST_ERR_NOENT;
 699                 if (!strcmp(iter->event_name, "lttng_ust:metadata"))
 700                         goto retry;
 701                 memcpy(tp, iter, sizeof(*tp));
 702                 return 0;
 703         }
 704         default:
 705                 return -EINVAL;
 706         }
 707 }
 708
 709 static
 710 int lttng_abi_tracepoint_field_list(void *owner)
 711 {
 712         int list_objd, ret;
 713         struct lttng_ust_field_list *list;
 714
 715         list_objd = objd_alloc(NULL, &lttng_tracepoint_field_list_ops, owner,
 716                         "tp_field_list");
 717         if (list_objd < 0) {
 718                 ret = list_objd;
 719                 goto objd_error;
 720         }
 721         list = zmalloc(sizeof(*list));
 722         if (!list) {
 723                 ret = -ENOMEM;
 724                 goto alloc_error;
 725         }
 726         objd_set_private(list_objd, list);
 727
 728         /* populate list by walking on all registered probes. */
 729         ret = lttng_probes_get_field_list(list);
 730         if (ret) {
 731                 goto list_error;
 732         }
 733         return list_objd;
 734
 735 list_error:
 736         free(list);
 737 alloc_error:
 738         {
 739                 int err;
 740
 741                 err = lttng_ust_objd_unref(list_objd);
 742                 assert(!err);
 743         }
 744 objd_error:
 745         return ret;
 746 }
 747
 748 static
 749 int lttng_release_tracepoint_field_list(int objd)
 750 {
 751         struct lttng_ust_field_list *list = objd_private(objd);
 752
 753         if (list) {
 754                 lttng_probes_prune_field_list(list);
 755                 free(list);
 756                 return 0;
 757         } else {
 758                 return -EINVAL;
 759         }
 760 }
 761
 762 static const struct lttng_ust_objd_ops lttng_tracepoint_field_list_ops = {
 763         .release = lttng_release_tracepoint_field_list,
 764         .cmd = lttng_tracepoint_field_list_cmd,
 765 };
 766
 767 static
 768 int lttng_abi_map_stream(int channel_objd, struct lttng_ust_stream *info,
 769                 union ust_args *uargs, void *owner)
 770 {
 771         struct lttng_channel *channel = objd_private(channel_objd);
 772         int ret;
 773
 774         ret = channel_handle_add_stream(channel->handle,
 775                 uargs->stream.shm_fd, uargs->stream.wakeup_fd,
 776                 info->stream_nr, info->len);
 777         if (ret)
 778                 goto error_add_stream;
 779
 780         return 0;
 781
 782 error_add_stream:
 783         return ret;
 784 }
 785
 786 static
 787 int lttng_abi_create_enabler(int channel_objd,
 788                            struct lttng_ust_event *event_param,
 789                            void *owner,
 790                            enum lttng_enabler_type type)
 791 {
 792         struct lttng_channel *channel = objd_private(channel_objd);
 793         struct lttng_enabler *enabler;
 794         int event_objd, ret;
 795
 796         event_param->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 797         event_objd = objd_alloc(NULL, &lttng_enabler_ops, owner, "enabler");
 798         if (event_objd < 0) {
 799                 ret = event_objd;
 800                 goto objd_error;
 801         }
 802         /*
 803          * We tolerate no failure path after event creation. It will stay
 804          * invariant for the rest of the session.
 805          */
 806         enabler = lttng_enabler_create(type, event_param, channel);
 807         if (!enabler) {
 808                 ret = -ENOMEM;
 809                 goto event_error;
 810         }
 811         objd_set_private(event_objd, enabler);
 812         /* The event holds a reference on the channel */
 813         objd_ref(channel_objd);
 814         return event_objd;
 815
 816 event_error:
 817         {
 818                 int err;
 819
 820                 err = lttng_ust_objd_unref(event_objd);
 821                 assert(!err);
 822         }
 823 objd_error:
 824         return ret;
 825 }
 826
 827 static
 828 long lttng_metadata_cmd(int objd, unsigned int cmd, unsigned long arg,
 829         union ust_args *uargs, void *owner)
 830 {
 831         struct lttng_channel *channel = objd_private(objd);
 832         struct lttng_session *session = channel->session;
 833
 834         switch (cmd) {
 835         case LTTNG_UST_STREAM:
 836         {
 837                 struct lttng_ust_stream *stream;
 838                 int ret;
 839
 840                 stream = (struct lttng_ust_stream *) arg;
 841                 /* stream used as output */
 842                 ret = lttng_abi_map_stream(objd, stream, uargs, owner);
 843                 if (ret == 0) {
 844                         session->metadata = channel;
 845                         lttng_metadata_create_events(objd);
 846                 }
 847                 return ret;
 848         }
 849         case LTTNG_UST_FLUSH_BUFFER:
 850         {
 851                 if (!session->metadata) {
 852                         return -ENOENT;
 853                 }
 854                 return channel->ops->flush_buffer(channel->chan, channel->handle);
 855         }
 856         default:
 857                 return -EINVAL;
 858         }
 859 }
 860
 861 /**
 862  *      lttng_channel_cmd - lttng control through object descriptors
 863  *
 864  *      @objd: the object descriptor
 865  *      @cmd: the command
 866  *      @arg: command arg
 867  *      @uargs: UST arguments (internal)
 868  *      @owner: objd owner
 869  *
 870  *      This object descriptor implements lttng commands:
 871  *      LTTNG_UST_STREAM
 872  *              Returns an event stream object descriptor or failure.
 873  *              (typically, one event stream records events from one CPU)
 874  *      LTTNG_UST_EVENT
 875  *              Returns an event object descriptor or failure.
 876  *      LTTNG_UST_CONTEXT
 877  *              Prepend a context field to each event in the channel
 878  *      LTTNG_UST_ENABLE
 879  *              Enable recording for events in this channel (weak enable)
 880  *      LTTNG_UST_DISABLE
 881  *              Disable recording for events in this channel (strong disable)
 882  *
 883  * Channel and event file descriptors also hold a reference on the session.
 884  */
 885 static
 886 long lttng_channel_cmd(int objd, unsigned int cmd, unsigned long arg,
 887         union ust_args *uargs, void *owner)
 888 {
 889         struct lttng_channel *channel = objd_private(objd);
 890
 891         if (cmd != LTTNG_UST_STREAM) {
 892                 /*
 893                  * Check if channel received all streams.
 894                  */
 895                 if (!lttng_is_channel_ready(channel))
 896                         return -EPERM;
 897         }
 898
 899         if (channel->type == LTTNG_UST_CHAN_METADATA) {
 900                 return lttng_metadata_cmd(objd, cmd, arg, uargs, owner);
 901         }
 902
 903         switch (cmd) {
 904         case LTTNG_UST_STREAM:
 905         {
 906                 struct lttng_ust_stream *stream;
 907
 908                 stream = (struct lttng_ust_stream *) arg;
 909                 /* stream used as output */
 910                 return lttng_abi_map_stream(objd, stream, uargs, owner);
 911         }
 912         case LTTNG_UST_EVENT:
 913         {
 914                 struct lttng_ust_event *event_param =
 915                         (struct lttng_ust_event *) arg;
 916                 if (event_param->name[strlen(event_param->name) - 1] == '*') {
 917                         /* If ends with wildcard, create wildcard. */
 918                         return lttng_abi_create_enabler(objd, event_param,
 919                                         owner, LTTNG_ENABLER_WILDCARD);
 920                 } else {
 921                         return lttng_abi_create_enabler(objd, event_param,
 922                                         owner, LTTNG_ENABLER_EVENT);
 923                 }
 924         }
 925         case LTTNG_UST_CONTEXT:
 926                 return lttng_abi_add_context(objd,
 927                                 (struct lttng_ust_context *) arg,
 928                                 &channel->ctx, channel->session);
 929         case LTTNG_UST_ENABLE:
 930                 return lttng_channel_enable(channel);
 931         case LTTNG_UST_DISABLE:
 932                 return lttng_channel_disable(channel);
 933         case LTTNG_UST_FLUSH_BUFFER:
 934                 return channel->ops->flush_buffer(channel->chan, channel->handle);
 935         default:
 936                 return -EINVAL;
 937         }
 938 }
 939
 940 static
 941 int lttng_channel_release(int objd)
 942 {
 943         struct lttng_channel *channel = objd_private(objd);
 944
 945         if (channel)
 946                 return lttng_ust_objd_unref(channel->session->objd);
 947         return 0;
 948 }
 949
 950 static const struct lttng_ust_objd_ops lttng_channel_ops = {
 951         .release = lttng_channel_release,
 952         .cmd = lttng_channel_cmd,
 953 };
 954
 955 /**
 956  *      lttng_enabler_cmd - lttng control through object descriptors
 957  *
 958  *      @objd: the object descriptor
 959  *      @cmd: the command
 960  *      @arg: command arg
 961  *      @uargs: UST arguments (internal)
 962  *      @owner: objd owner
 963  *
 964  *      This object descriptor implements lttng commands:
 965  *      LTTNG_UST_CONTEXT
 966  *              Prepend a context field to each record of events of this
 967  *              enabler.
 968  *      LTTNG_UST_ENABLE
 969  *              Enable recording for this enabler
 970  *      LTTNG_UST_DISABLE
 971  *              Disable recording for this enabler
 972  *      LTTNG_UST_FILTER
 973  *              Attach a filter to an enabler.
 974  */
 975 static
 976 long lttng_enabler_cmd(int objd, unsigned int cmd, unsigned long arg,
 977         union ust_args *uargs, void *owner)
 978 {
 979         struct lttng_enabler *enabler = objd_private(objd);
 980
 981         switch (cmd) {
 982         case LTTNG_UST_CONTEXT:
 983                 return lttng_enabler_attach_context(enabler,
 984                                 (struct lttng_ust_context *) arg);
 985         case LTTNG_UST_ENABLE:
 986                 return lttng_enabler_enable(enabler);
 987         case LTTNG_UST_DISABLE:
 988                 return lttng_enabler_disable(enabler);
 989         case LTTNG_UST_FILTER:
 990         {
 991                 int ret;
 992
 993                 ret = lttng_enabler_attach_bytecode(enabler,
 994                                 (struct lttng_ust_filter_bytecode_node *) arg);
 995                 if (ret)
 996                         return ret;
 997                 return 0;
 998         }
 999         default:
1000                 return -EINVAL;
1001         }
1002 }
1003
1004 static
1005 int lttng_enabler_release(int objd)
1006 {
1007         struct lttng_enabler *enabler = objd_private(objd);
1008
1009         if (enabler)
1010                 return lttng_ust_objd_unref(enabler->chan->objd);
1011         return 0;
1012 }
1013
1014 static const struct lttng_ust_objd_ops lttng_enabler_ops = {
1015         .release = lttng_enabler_release,
1016         .cmd = lttng_enabler_cmd,
1017 };
1018
1019 void lttng_ust_abi_exit(void)
1020 {
1021         lttng_ust_abi_close_in_progress = 1;
1022         objd_table_destroy();
1023         lttng_ust_abi_close_in_progress = 0;
1024 }