liblttng-ust/lttng-ust-abi.c

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