liblttng-ust-ctl/ustctl.c

   1 /*
   2  * Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
   3  *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License
   7  * as published by the Free Software Foundation; only version 2
   8  * of the License.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  18  */
  19
  20 #include <string.h>
  21 #include <lttng/ust-ctl.h>
  22 #include <lttng/ust-abi.h>
  23 #include <lttng/usterr-signal-safe.h>
  24 #include <lttng/ust-comm.h>
  25
  26 #include "../libringbuffer/backend.h"
  27 #include "../libringbuffer/frontend.h"
  28
  29 volatile enum ust_loglevel ust_loglevel;
  30
  31 static
  32 void init_object(struct lttng_ust_object_data *data)
  33 {
  34         data->handle = -1;
  35         data->shm_fd = -1;
  36         data->wait_fd = -1;
  37         data->memory_map_size = 0;
  38 }
  39
  40 void release_object(int sock, struct lttng_ust_object_data *data)
  41 {
  42         struct ustcomm_ust_msg lum;
  43         struct ustcomm_ust_reply lur;
  44         int ret;
  45
  46         if (data->shm_fd >= 0)
  47                 close(data->shm_fd);
  48         if (data->wait_fd >= 0)
  49                 close(data->wait_fd);
  50         memset(&lum, 0, sizeof(lum));
  51         lum.handle = data->handle;
  52         lum.cmd = LTTNG_UST_RELEASE;
  53         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
  54         assert(!ret);
  55         free(data);
  56 }
  57
  58 /*
  59  * Send registration done packet to the application.
  60  */
  61 int ustctl_register_done(int sock)
  62 {
  63         struct ustcomm_ust_msg lum;
  64         struct ustcomm_ust_reply lur;
  65         int ret;
  66
  67         DBG("Sending register done command to %d", sock);
  68         memset(&lum, 0, sizeof(lum));
  69         lum.handle = LTTNG_UST_ROOT_HANDLE;
  70         lum.cmd = LTTNG_UST_REGISTER_DONE;
  71         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
  72         if (ret)
  73                 return ret;
  74         if (lur.ret_code != USTCOMM_OK) {
  75                 DBG("Return code: %s", ustcomm_get_readable_code(lur.ret_code));
  76                 goto error;
  77         }
  78         return 0;
  79
  80 error:
  81         return -1;
  82 }
  83
  84 /*
  85  * returns session handle.
  86  */
  87 int ustctl_create_session(int sock)
  88 {
  89         struct ustcomm_ust_msg lum;
  90         struct ustcomm_ust_reply lur;
  91         int ret, session_handle;
  92
  93         /* Create session */
  94         memset(&lum, 0, sizeof(lum));
  95         lum.handle = LTTNG_UST_ROOT_HANDLE;
  96         lum.cmd = LTTNG_UST_SESSION;
  97         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
  98         if (ret)
  99                 return ret;
 100         session_handle = lur.ret_val;
 101         DBG("received session handle %u", session_handle);
 102         return session_handle;
 103 }
 104
 105 /* open the metadata global channel */
 106 int ustctl_open_metadata(int sock, int session_handle,
 107                 struct lttng_ust_channel_attr *chops,
 108                 struct lttng_ust_object_data **_metadata_data)
 109 {
 110         struct ustcomm_ust_msg lum;
 111         struct ustcomm_ust_reply lur;
 112         struct lttng_ust_object_data *metadata_data;
 113         int ret;
 114
 115         metadata_data = malloc(sizeof(*metadata_data));
 116         if (!metadata_data)
 117                 return -ENOMEM;
 118         init_object(metadata_data);
 119         /* Create metadata channel */
 120         memset(&lum, 0, sizeof(lum));
 121         lum.handle = session_handle;
 122         lum.cmd = LTTNG_UST_METADATA;
 123         lum.u.channel.overwrite = chops->overwrite;
 124         lum.u.channel.subbuf_size = chops->subbuf_size;
 125         lum.u.channel.num_subbuf = chops->num_subbuf;
 126         lum.u.channel.switch_timer_interval = chops->switch_timer_interval;
 127         lum.u.channel.read_timer_interval = chops->read_timer_interval;
 128         lum.u.channel.output = chops->output;
 129         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 130         if (ret) {
 131                 free(metadata_data);
 132                 return ret;
 133         }
 134         if (lur.ret_code != USTCOMM_OK) {
 135                 free(metadata_data);
 136                 return lur.ret_code;
 137         }
 138         metadata_data->handle = lur.ret_val;
 139         DBG("received metadata handle %u", metadata_data->handle);
 140         metadata_data->memory_map_size = lur.u.channel.memory_map_size;
 141         /* get shm fd */
 142         ret = ustcomm_recv_fd(sock);
 143         if (ret < 0)
 144                 goto error;
 145         metadata_data->shm_fd = ret;
 146         /* get wait fd */
 147         ret = ustcomm_recv_fd(sock);
 148         if (ret < 0)
 149                 goto error;
 150         metadata_data->wait_fd = ret;
 151         *_metadata_data = metadata_data;
 152         return 0;
 153
 154 error:
 155         release_object(sock, metadata_data);
 156         return -EINVAL;
 157 }
 158
 159 int ustctl_create_channel(int sock, int session_handle,
 160                 struct lttng_ust_channel_attr *chops,
 161                 struct lttng_ust_object_data **_channel_data)
 162 {
 163         struct ustcomm_ust_msg lum;
 164         struct ustcomm_ust_reply lur;
 165         struct lttng_ust_object_data *channel_data;
 166         int ret;
 167
 168         channel_data = malloc(sizeof(*channel_data));
 169         if (!channel_data)
 170                 return -ENOMEM;
 171         init_object(channel_data);
 172         /* Create metadata channel */
 173         memset(&lum, 0, sizeof(lum));
 174         lum.handle = session_handle;
 175         lum.cmd = LTTNG_UST_CHANNEL;
 176         lum.u.channel.overwrite = chops->overwrite;
 177         lum.u.channel.subbuf_size = chops->subbuf_size;
 178         lum.u.channel.num_subbuf = chops->num_subbuf;
 179         lum.u.channel.switch_timer_interval = chops->switch_timer_interval;
 180         lum.u.channel.read_timer_interval = chops->read_timer_interval;
 181         lum.u.channel.output = chops->output;
 182         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 183         if (ret) {
 184                 free(channel_data);
 185                 return ret;
 186         }
 187         if (lur.ret_code != USTCOMM_OK) {
 188                 free(channel_data);
 189                 return lur.ret_code;
 190         }
 191         channel_data->handle = lur.ret_val;
 192         DBG("received channel handle %u", channel_data->handle);
 193         channel_data->memory_map_size = lur.u.channel.memory_map_size;
 194         /* get shm fd */
 195         ret = ustcomm_recv_fd(sock);
 196         if (ret < 0)
 197                 goto error;
 198         channel_data->shm_fd = ret;
 199         /* get wait fd */
 200         ret = ustcomm_recv_fd(sock);
 201         if (ret < 0)
 202                 goto error;
 203         channel_data->wait_fd = ret;
 204         *_channel_data = channel_data;
 205         return 0;
 206
 207 error:
 208         release_object(sock, channel_data);
 209         return -EINVAL;
 210 }
 211
 212 /*
 213  * Return -ENOENT if no more stream is available for creation.
 214  * Return 0 on success.
 215  * Return negative error value on error.
 216  */
 217 int ustctl_create_stream(int sock, struct lttng_ust_object_data *channel_data,
 218                 struct lttng_ust_object_data **_stream_data)
 219 {
 220         struct ustcomm_ust_msg lum;
 221         struct ustcomm_ust_reply lur;
 222         struct lttng_ust_object_data *stream_data;
 223         int ret, fd;
 224
 225         stream_data = malloc(sizeof(*stream_data));
 226         if (!stream_data)
 227                 return -ENOMEM;
 228         init_object(stream_data);
 229         memset(&lum, 0, sizeof(lum));
 230         lum.handle = channel_data->handle;
 231         lum.cmd = LTTNG_UST_STREAM;
 232         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 233         if (ret) {
 234                 free(stream_data);
 235                 return ret;
 236         }
 237         if (lur.ret_code != USTCOMM_OK) {
 238                 free(stream_data);
 239                 return lur.ret_code;
 240         }
 241
 242         stream_data->handle = lur.ret_val;
 243         DBG("received stream handle %u", stream_data->handle);
 244         stream_data->memory_map_size = lur.u.stream.memory_map_size;
 245         /* get shm fd */
 246         fd = ustcomm_recv_fd(sock);
 247         if (fd < 0)
 248                 goto error;
 249         stream_data->shm_fd = fd;
 250         /* get wait fd */
 251         fd = ustcomm_recv_fd(sock);
 252         if (fd < 0)
 253                 goto error;
 254         stream_data->wait_fd = fd;
 255         *_stream_data = stream_data;
 256         return ret;
 257
 258 error:
 259         release_object(sock, stream_data);
 260         return -EINVAL;
 261 }
 262
 263 int ustctl_create_event(int sock, struct lttng_ust_event *ev,
 264                 struct lttng_ust_object_data *channel_data,
 265                 struct lttng_ust_object_data **_event_data)
 266 {
 267         struct ustcomm_ust_msg lum;
 268         struct ustcomm_ust_reply lur;
 269         struct lttng_ust_object_data *event_data;
 270         int ret;
 271
 272         event_data = malloc(sizeof(*event_data));
 273         if (!event_data)
 274                 return -ENOMEM;
 275         init_object(event_data);
 276         memset(&lum, 0, sizeof(lum));
 277         lum.handle = channel_data->handle;
 278         lum.cmd = LTTNG_UST_EVENT;
 279         strncpy(lum.u.event.name, ev->name,
 280                 LTTNG_UST_SYM_NAME_LEN);
 281         lum.u.event.instrumentation = ev->instrumentation;
 282         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 283         if (ret) {
 284                 free(event_data);
 285                 return ret;
 286         }
 287         event_data->handle = lur.ret_val;
 288         DBG("received event handle %u", event_data->handle);
 289         *_event_data = event_data;
 290         return 0;
 291 }
 292
 293 int ustctl_add_context(int sock, struct lttng_ust_context *ctx,
 294                 struct lttng_ust_object_data *obj_data,
 295                 struct lttng_ust_object_data **_context_data)
 296 {
 297         struct ustcomm_ust_msg lum;
 298         struct ustcomm_ust_reply lur;
 299         struct lttng_ust_object_data *context_data;
 300         int ret;
 301
 302         context_data = malloc(sizeof(*context_data));
 303         if (!context_data)
 304                 return -ENOMEM;
 305         init_object(context_data);
 306         memset(&lum, 0, sizeof(lum));
 307         lum.handle = obj_data->handle;
 308         lum.cmd = LTTNG_UST_CONTEXT;
 309         lum.u.context.ctx = ctx->ctx;
 310         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 311         if (ret) {
 312                 free(context_data);
 313                 return ret;
 314         }
 315         context_data->handle = lur.ret_val;
 316         DBG("received context handle %u", context_data->handle);
 317         *_context_data = context_data;
 318         return ret;
 319 }
 320
 321 /* Enable event, channel and session ioctl */
 322 int ustctl_enable(int sock, struct lttng_ust_object_data *object)
 323 {
 324         struct ustcomm_ust_msg lum;
 325         struct ustcomm_ust_reply lur;
 326         int ret;
 327
 328         memset(&lum, 0, sizeof(lum));
 329         lum.handle = object->handle;
 330         lum.cmd = LTTNG_UST_ENABLE;
 331         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 332         if (ret)
 333                 return ret;
 334         DBG("enabled handle %u", object->handle);
 335         return 0;
 336 }
 337
 338 /* Disable event, channel and session ioctl */
 339 int ustctl_disable(int sock, struct lttng_ust_object_data *object)
 340 {
 341         struct ustcomm_ust_msg lum;
 342         struct ustcomm_ust_reply lur;
 343         int ret;
 344
 345         memset(&lum, 0, sizeof(lum));
 346         lum.handle = object->handle;
 347         lum.cmd = LTTNG_UST_DISABLE;
 348         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 349         if (ret)
 350                 return ret;
 351         DBG("disable handle %u", object->handle);
 352         return 0;
 353 }
 354
 355 int ustctl_start_session(int sock, int handle)
 356 {
 357         struct lttng_ust_object_data obj;
 358
 359         obj.handle = handle;
 360         return ustctl_enable(sock, &obj);
 361 }
 362
 363 int ustctl_stop_session(int sock, int handle)
 364 {
 365         struct lttng_ust_object_data obj;
 366
 367         obj.handle = handle;
 368         return ustctl_disable(sock, &obj);
 369 }
 370
 371
 372 int ustctl_tracepoint_list(int sock)
 373 {
 374         return -ENOSYS; /* not implemented */
 375 }
 376
 377 int ustctl_tracer_version(int sock, struct lttng_ust_tracer_version *v)
 378 {
 379         struct ustcomm_ust_msg lum;
 380         struct ustcomm_ust_reply lur;
 381         int ret;
 382
 383         memset(&lum, 0, sizeof(lum));
 384         lum.handle = LTTNG_UST_ROOT_HANDLE;
 385         lum.cmd = LTTNG_UST_TRACER_VERSION;
 386         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 387         if (ret)
 388                 return ret;
 389         memcpy(v, &lur.u.version, sizeof(*v));
 390         DBG("received tracer version");
 391         return 0;
 392 }
 393
 394 int ustctl_wait_quiescent(int sock)
 395 {
 396         struct ustcomm_ust_msg lum;
 397         struct ustcomm_ust_reply lur;
 398         int ret;
 399
 400         memset(&lum, 0, sizeof(lum));
 401         lum.handle = LTTNG_UST_ROOT_HANDLE;
 402         lum.cmd = LTTNG_UST_WAIT_QUIESCENT;
 403         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 404         if (ret)
 405                 return ret;
 406         DBG("waited for quiescent state");
 407         return 0;
 408 }
 409
 410 int ustctl_flush_buffer(int sock, struct lttng_ust_object_data *channel_data)
 411 {
 412         struct ustcomm_ust_msg lum;
 413         struct ustcomm_ust_reply lur;
 414
 415         memset(&lum, 0, sizeof(lum));
 416         lum.handle = channel_data->handle;
 417         lum.cmd = LTTNG_UST_FLUSH_BUFFER;
 418         return ustcomm_send_app_cmd(sock, &lum, &lur);
 419 }
 420
 421 int ustctl_calibrate(int sock, struct lttng_ust_calibrate *calibrate)
 422 {
 423         return -ENOSYS;
 424 }
 425
 426 /* Buffer operations */
 427
 428 /* Map channel shm into process memory */
 429 struct lttng_ust_shm_handle *ustctl_map_channel(struct lttng_ust_object_data *chan_data)
 430 {
 431         struct lttng_ust_shm_handle *handle;
 432         struct channel *chan;
 433         size_t chan_size;
 434
 435         handle = channel_handle_create(chan_data->shm_fd,
 436                 chan_data->wait_fd,
 437                 chan_data->memory_map_size);
 438         if (!handle) {
 439                 ERR("create handle error");
 440                 return NULL;
 441         }
 442         /*
 443          * Set to -1 because the lttng_ust_shm_handle destruction will take care
 444          * of closing shm_fd and wait_fd.
 445          */
 446         chan_data->shm_fd = -1;
 447         chan_data->wait_fd = -1;
 448
 449         /*
 450          * TODO: add consistency checks to be resilient if the
 451          * application try to feed us with incoherent channel structure
 452          * values.
 453          */
 454         chan = shmp(handle, handle->chan);
 455         /* chan is object 0. This is hardcoded. */
 456         chan_size = handle->table->objects[0].allocated_len;
 457         handle->shadow_chan = malloc(chan_size);
 458         if (!handle->shadow_chan) {
 459                 channel_destroy(chan, handle, 1);
 460                 return NULL;
 461         }
 462         memcpy(handle->shadow_chan, chan, chan_size);
 463         return handle;
 464 }
 465
 466 /* Add stream to channel shm and map its shm into process memory */
 467 int ustctl_add_stream(struct lttng_ust_shm_handle *handle,
 468                 struct lttng_ust_object_data *stream_data)
 469 {
 470         int ret;
 471
 472         if (!stream_data->handle)
 473                 return -ENOENT;
 474         /* map stream */
 475         ret = channel_handle_add_stream(handle,
 476                 stream_data->shm_fd,
 477                 stream_data->wait_fd,
 478                 stream_data->memory_map_size);
 479         if (ret) {
 480                 ERR("add stream error\n");
 481                 return ret;
 482         }
 483         /*
 484          * Set to -1 because the lttng_ust_shm_handle destruction will take care
 485          * of closing shm_fd and wait_fd.
 486          */
 487         stream_data->shm_fd = -1;
 488         stream_data->wait_fd = -1;
 489         return 0;
 490 }
 491
 492 void ustctl_unmap_channel(struct lttng_ust_shm_handle *handle)
 493 {
 494         struct channel *chan;
 495
 496         chan = shmp(handle, handle->chan);
 497         channel_destroy(chan, handle, 1);
 498 }
 499
 500 struct lttng_ust_lib_ring_buffer *ustctl_open_stream_read(struct lttng_ust_shm_handle *handle,
 501         int cpu)
 502 {
 503         struct channel *chan = handle->shadow_chan;
 504         int shm_fd, wait_fd;
 505         uint64_t memory_map_size;
 506         struct lttng_ust_lib_ring_buffer *buf;
 507         int ret;
 508
 509         buf = channel_get_ring_buffer(&chan->backend.config,
 510                 chan, cpu, handle, &shm_fd, &wait_fd, &memory_map_size);
 511         if (!buf)
 512                 return NULL;
 513         ret = lib_ring_buffer_open_read(buf, handle, 1);
 514         if (ret)
 515                 return NULL;
 516         return buf;
 517 }
 518
 519 void ustctl_close_stream_read(struct lttng_ust_shm_handle *handle,
 520                 struct lttng_ust_lib_ring_buffer *buf)
 521 {
 522         lib_ring_buffer_release_read(buf, handle, 1);
 523 }
 524
 525 /* For mmap mode, readable without "get" operation */
 526
 527 void *ustctl_get_mmap_base(struct lttng_ust_shm_handle *handle,
 528                 struct lttng_ust_lib_ring_buffer *buf)
 529 {
 530         return shmp(handle, buf->backend.memory_map);
 531 }
 532
 533 /* returns the length to mmap. */
 534 int ustctl_get_mmap_len(struct lttng_ust_shm_handle *handle,
 535                 struct lttng_ust_lib_ring_buffer *buf,
 536                 unsigned long *len)
 537 {
 538         unsigned long mmap_buf_len;
 539         struct channel *chan = handle->shadow_chan;
 540
 541         if (chan->backend.config.output != RING_BUFFER_MMAP)
 542                 return -EINVAL;
 543         mmap_buf_len = chan->backend.buf_size;
 544         if (chan->backend.extra_reader_sb)
 545                 mmap_buf_len += chan->backend.subbuf_size;
 546         if (mmap_buf_len > INT_MAX)
 547                 return -EFBIG;
 548         *len = mmap_buf_len;
 549         return 0;
 550 }
 551
 552 /* returns the maximum size for sub-buffers. */
 553 int ustctl_get_max_subbuf_size(struct lttng_ust_shm_handle *handle,
 554                 struct lttng_ust_lib_ring_buffer *buf,
 555                 unsigned long *len)
 556 {
 557         struct channel *chan = handle->shadow_chan;
 558
 559         *len = chan->backend.subbuf_size;
 560         return 0;
 561 }
 562
 563 /*
 564  * For mmap mode, operate on the current packet (between get/put or
 565  * get_next/put_next).
 566  */
 567
 568 /* returns the offset of the subbuffer belonging to the mmap reader. */
 569 int ustctl_get_mmap_read_offset(struct lttng_ust_shm_handle *handle,
 570                 struct lttng_ust_lib_ring_buffer *buf, unsigned long *off)
 571 {
 572         struct channel *chan = handle->shadow_chan;
 573         unsigned long sb_bindex;
 574
 575         if (chan->backend.config.output != RING_BUFFER_MMAP)
 576                 return -EINVAL;
 577         sb_bindex = subbuffer_id_get_index(&chan->backend.config,
 578                                            buf->backend.buf_rsb.id);
 579         *off = shmp(handle, shmp_index(handle, buf->backend.array, sb_bindex)->shmp)->mmap_offset;
 580         return 0;
 581 }
 582
 583 /* returns the size of the current sub-buffer, without padding (for mmap). */
 584 int ustctl_get_subbuf_size(struct lttng_ust_shm_handle *handle,
 585                 struct lttng_ust_lib_ring_buffer *buf, unsigned long *len)
 586 {
 587         struct channel *chan = handle->shadow_chan;
 588
 589         *len = lib_ring_buffer_get_read_data_size(&chan->backend.config, buf,
 590                 handle);
 591         return 0;
 592 }
 593
 594 /* returns the size of the current sub-buffer, without padding (for mmap). */
 595 int ustctl_get_padded_subbuf_size(struct lttng_ust_shm_handle *handle,
 596                 struct lttng_ust_lib_ring_buffer *buf, unsigned long *len)
 597 {
 598         struct channel *chan = handle->shadow_chan;
 599
 600         *len = lib_ring_buffer_get_read_data_size(&chan->backend.config, buf,
 601                 handle);
 602         *len = PAGE_ALIGN(*len);
 603         return 0;
 604 }
 605
 606 /* Get exclusive read access to the next sub-buffer that can be read. */
 607 int ustctl_get_next_subbuf(struct lttng_ust_shm_handle *handle,
 608                 struct lttng_ust_lib_ring_buffer *buf)
 609 {
 610         return lib_ring_buffer_get_next_subbuf(buf, handle);
 611 }
 612
 613
 614 /* Release exclusive sub-buffer access, move consumer forward. */
 615 int ustctl_put_next_subbuf(struct lttng_ust_shm_handle *handle,
 616                 struct lttng_ust_lib_ring_buffer *buf)
 617 {
 618         lib_ring_buffer_put_next_subbuf(buf, handle);
 619         return 0;
 620 }
 621
 622 /* snapshot */
 623
 624 /* Get a snapshot of the current ring buffer producer and consumer positions */
 625 int ustctl_snapshot(struct lttng_ust_shm_handle *handle,
 626                 struct lttng_ust_lib_ring_buffer *buf)
 627 {
 628         return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
 629                         &buf->prod_snapshot, handle);
 630 }
 631
 632 /* Get the consumer position (iteration start) */
 633 int ustctl_snapshot_get_consumed(struct lttng_ust_shm_handle *handle,
 634                 struct lttng_ust_lib_ring_buffer *buf, unsigned long *pos)
 635 {
 636         *pos = buf->cons_snapshot;
 637         return 0;
 638 }
 639
 640 /* Get the producer position (iteration end) */
 641 int ustctl_snapshot_get_produced(struct lttng_ust_shm_handle *handle,
 642                 struct lttng_ust_lib_ring_buffer *buf, unsigned long *pos)
 643 {
 644         *pos = buf->prod_snapshot;
 645         return 0;
 646 }
 647
 648 /* Get exclusive read access to the specified sub-buffer position */
 649 int ustctl_get_subbuf(struct lttng_ust_shm_handle *handle,
 650                 struct lttng_ust_lib_ring_buffer *buf, unsigned long *pos)
 651 {
 652         return lib_ring_buffer_get_subbuf(buf, *pos, handle);
 653 }
 654
 655 /* Release exclusive sub-buffer access */
 656 int ustctl_put_subbuf(struct lttng_ust_shm_handle *handle,
 657                 struct lttng_ust_lib_ring_buffer *buf)
 658 {
 659         lib_ring_buffer_put_subbuf(buf, handle);
 660         return 0;
 661 }
 662
 663 int ustctl_buffer_flush(struct lttng_ust_shm_handle *handle,
 664                 struct lttng_ust_lib_ring_buffer *buf)
 665 {
 666         lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE, handle);
 667         return 0;
 668 }