src/common/kernel-ctl/kernel-ctl.c

   1 /*
   2  * Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
   3  *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *               2016 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License, version 2 only,
   8  * as published by the Free Software Foundation.
   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 along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19
  20 #define _LGPL_SOURCE
  21 #define __USE_LINUX_IOCTL_DEFS
  22 #include <sys/ioctl.h>
  23 #include <string.h>
  24 #include <common/align.h>
  25 #include <errno.h>
  26 #include <stdarg.h>
  27 #include <assert.h>
  28
  29 #include "kernel-ctl.h"
  30 #include "kernel-ioctl.h"
  31
  32 #define LTTNG_IOCTL_CHECK(fildes, request, ...) ({      \
  33         int ret = ioctl(fildes, request, ##__VA_ARGS__);\
  34         assert(ret <= 0);                               \
  35         !ret ? 0 : -errno;                              \
  36 })
  37
  38 #define LTTNG_IOCTL_NO_CHECK(fildes, request, ...) ({   \
  39         int ret = ioctl(fildes, request, ##__VA_ARGS__);\
  40         ret >= 0 ? ret : -errno;                        \
  41 })
  42
  43 /*
  44  * This flag indicates which version of the kernel ABI to use. The old
  45  * ABI (namespace _old) does not support a 32-bit user-space when the
  46  * kernel is 64-bit. The old ABI is kept here for compatibility but is
  47  * deprecated and will be removed eventually.
  48  */
  49 static int lttng_kernel_use_old_abi = -1;
  50
  51 /*
  52  * Execute the new or old ioctl depending on the ABI version.
  53  * If the ABI version is not determined yet (lttng_kernel_use_old_abi = -1),
  54  * this function tests if the new ABI is available and otherwise fallbacks
  55  * on the old one.
  56  * This function takes the fd on which the ioctl must be executed and the old
  57  * and new request codes.
  58  * It returns the return value of the ioctl executed.
  59  */
  60 static inline int compat_ioctl_no_arg(int fd, unsigned long oldname,
  61                 unsigned long newname)
  62 {
  63         int ret;
  64
  65         if (lttng_kernel_use_old_abi == -1) {
  66                 ret = LTTNG_IOCTL_NO_CHECK(fd, newname);
  67                 if (!ret) {
  68                         lttng_kernel_use_old_abi = 0;
  69                         goto end;
  70                 }
  71                 lttng_kernel_use_old_abi = 1;
  72         }
  73         if (lttng_kernel_use_old_abi) {
  74                 ret = LTTNG_IOCTL_NO_CHECK(fd, oldname);
  75         } else {
  76                 ret = LTTNG_IOCTL_NO_CHECK(fd, newname);
  77         }
  78
  79 end:
  80         return ret;
  81 }
  82
  83 int kernctl_create_session(int fd)
  84 {
  85         return compat_ioctl_no_arg(fd, LTTNG_KERNEL_OLD_SESSION,
  86                         LTTNG_KERNEL_SESSION);
  87 }
  88
  89 /* open the metadata global channel */
  90 int kernctl_open_metadata(int fd, struct lttng_channel_attr *chops)
  91 {
  92         struct lttng_kernel_channel channel;
  93
  94         if (lttng_kernel_use_old_abi) {
  95                 struct lttng_kernel_old_channel old_channel;
  96
  97                 memset(&old_channel, 0, sizeof(old_channel));
  98                 old_channel.overwrite = chops->overwrite;
  99                 old_channel.subbuf_size = chops->subbuf_size;
 100                 old_channel.num_subbuf = chops->num_subbuf;
 101                 old_channel.switch_timer_interval = chops->switch_timer_interval;
 102                 old_channel.read_timer_interval = chops->read_timer_interval;
 103                 old_channel.output = chops->output;
 104
 105                 memset(old_channel.padding, 0, sizeof(old_channel.padding));
 106                 /*
 107                  * The new channel padding is smaller than the old ABI so we use the
 108                  * new ABI padding size for the memcpy.
 109                  */
 110                 memcpy(old_channel.padding, chops->padding, sizeof(chops->padding));
 111
 112                 return LTTNG_IOCTL_NO_CHECK(fd, LTTNG_KERNEL_OLD_METADATA,
 113                                 &old_channel);
 114         }
 115
 116         memset(&channel, 0, sizeof(channel));
 117         channel.overwrite = chops->overwrite;
 118         channel.subbuf_size = chops->subbuf_size;
 119         channel.num_subbuf = chops->num_subbuf;
 120         channel.switch_timer_interval = chops->switch_timer_interval;
 121         channel.read_timer_interval = chops->read_timer_interval;
 122         channel.output = chops->output;
 123         memcpy(channel.padding, chops->padding, sizeof(chops->padding));
 124
 125         return LTTNG_IOCTL_NO_CHECK(fd, LTTNG_KERNEL_METADATA, &channel);
 126 }
 127
 128 int kernctl_create_channel(int fd, struct lttng_channel_attr *chops)
 129 {
 130         struct lttng_kernel_channel channel;
 131
 132         memset(&channel, 0, sizeof(channel));
 133         if (lttng_kernel_use_old_abi) {
 134                 struct lttng_kernel_old_channel old_channel;
 135
 136                 old_channel.overwrite = chops->overwrite;
 137                 old_channel.subbuf_size = chops->subbuf_size;
 138                 old_channel.num_subbuf = chops->num_subbuf;
 139                 old_channel.switch_timer_interval = chops->switch_timer_interval;
 140                 old_channel.read_timer_interval = chops->read_timer_interval;
 141                 old_channel.output = chops->output;
 142
 143                 memset(old_channel.padding, 0, sizeof(old_channel.padding));
 144                 /*
 145                  * The new channel padding is smaller than the old ABI so we use the
 146                  * new ABI padding size for the memcpy.
 147                  */
 148                 memcpy(old_channel.padding, chops->padding, sizeof(chops->padding));
 149
 150                 return LTTNG_IOCTL_NO_CHECK(fd, LTTNG_KERNEL_OLD_CHANNEL,
 151                                 &old_channel);
 152         }
 153
 154         channel.overwrite = chops->overwrite;
 155         channel.subbuf_size = chops->subbuf_size;
 156         channel.num_subbuf = chops->num_subbuf;
 157         channel.switch_timer_interval = chops->switch_timer_interval;
 158         channel.read_timer_interval = chops->read_timer_interval;
 159         channel.output = chops->output;
 160         memcpy(channel.padding, chops->padding, sizeof(chops->padding));
 161
 162         return LTTNG_IOCTL_NO_CHECK(fd, LTTNG_KERNEL_CHANNEL, &channel);
 163 }
 164
 165 int kernctl_syscall_mask(int fd, char **syscall_mask, uint32_t *nr_bits)
 166 {
 167         struct lttng_kernel_syscall_mask kmask_len, *kmask = NULL;
 168         size_t array_alloc_len;
 169         char *new_mask;
 170         int ret = 0;
 171
 172         if (!syscall_mask) {
 173                 ret = -1;
 174                 goto end;
 175         }
 176
 177         if (!nr_bits) {
 178                 ret = -1;
 179                 goto end;
 180         }
 181
 182         kmask_len.len = 0;
 183         ret = LTTNG_IOCTL_CHECK(fd, LTTNG_KERNEL_SYSCALL_MASK, &kmask_len);
 184         if (ret) {
 185                 goto end;
 186         }
 187
 188         array_alloc_len = ALIGN(kmask_len.len, 8) >> 3;
 189
 190         kmask = zmalloc(sizeof(*kmask) + array_alloc_len);
 191         if (!kmask) {
 192                 ret = -1;
 193                 goto end;
 194         }
 195
 196         kmask->len = kmask_len.len;
 197         ret = LTTNG_IOCTL_CHECK(fd, LTTNG_KERNEL_SYSCALL_MASK, kmask);
 198         if (ret) {
 199                 goto end;
 200         }
 201
 202         new_mask = realloc(*syscall_mask, array_alloc_len);
 203         if (!new_mask) {
 204                 ret = -1;
 205                 goto end;
 206         }
 207         memcpy(new_mask, kmask->mask, array_alloc_len);
 208         *syscall_mask = new_mask;
 209         *nr_bits = kmask->len;
 210
 211 end:
 212         free(kmask);
 213         return ret;
 214 }
 215
 216 int kernctl_track_pid(int fd, int pid)
 217 {
 218         return LTTNG_IOCTL_CHECK(fd, LTTNG_KERNEL_SESSION_TRACK_PID, pid);
 219 }
 220
 221 int kernctl_untrack_pid(int fd, int pid)
 222 {
 223         return LTTNG_IOCTL_CHECK(fd, LTTNG_KERNEL_SESSION_UNTRACK_PID, pid);
 224 }
 225
 226 int kernctl_list_tracker_pids(int fd)
 227 {
 228         return LTTNG_IOCTL_NO_CHECK(fd, LTTNG_KERNEL_SESSION_LIST_TRACKER_PIDS);
 229 }
 230
 231 int kernctl_session_regenerate_metadata(int fd)
 232 {
 233         return LTTNG_IOCTL_CHECK(fd, LTTNG_KERNEL_SESSION_METADATA_REGEN);
 234 }
 235
 236 int kernctl_session_regenerate_statedump(int fd)
 237 {
 238         return LTTNG_IOCTL_CHECK(fd, LTTNG_KERNEL_SESSION_STATEDUMP);
 239 }
 240
 241 int kernctl_create_stream(int fd)
 242 {
 243         return compat_ioctl_no_arg(fd, LTTNG_KERNEL_OLD_STREAM,
 244                         LTTNG_KERNEL_STREAM);
 245 }
 246
 247 int kernctl_create_event(int fd, struct lttng_kernel_event *ev)
 248 {
 249         if (lttng_kernel_use_old_abi) {
 250                 struct lttng_kernel_old_event old_event;
 251
 252                 memset(&old_event, 0, sizeof(old_event));
 253                 memcpy(old_event.name, ev->name, sizeof(old_event.name));
 254                 old_event.instrumentation = ev->instrumentation;
 255                 switch (ev->instrumentation) {
 256                 case LTTNG_KERNEL_KPROBE:
 257                         old_event.u.kprobe.addr = ev->u.kprobe.addr;
 258                         old_event.u.kprobe.offset = ev->u.kprobe.offset;
 259                         memcpy(old_event.u.kprobe.symbol_name,
 260                                 ev->u.kprobe.symbol_name,
 261                                 sizeof(old_event.u.kprobe.symbol_name));
 262                         break;
 263                 case LTTNG_KERNEL_KRETPROBE:
 264                         old_event.u.kretprobe.addr = ev->u.kretprobe.addr;
 265                         old_event.u.kretprobe.offset = ev->u.kretprobe.offset;
 266                         memcpy(old_event.u.kretprobe.symbol_name,
 267                                 ev->u.kretprobe.symbol_name,
 268                                 sizeof(old_event.u.kretprobe.symbol_name));
 269                         break;
 270                 case LTTNG_KERNEL_FUNCTION:
 271                         memcpy(old_event.u.ftrace.symbol_name,
 272                                         ev->u.ftrace.symbol_name,
 273                                         sizeof(old_event.u.ftrace.symbol_name));
 274                         break;
 275                 default:
 276                         break;
 277                 }
 278
 279                 return LTTNG_IOCTL_NO_CHECK(fd, LTTNG_KERNEL_OLD_EVENT,
 280                                 &old_event);
 281         }
 282         return LTTNG_IOCTL_NO_CHECK(fd, LTTNG_KERNEL_EVENT, ev);
 283 }
 284
 285 int kernctl_add_context(int fd, struct lttng_kernel_context *ctx)
 286 {
 287         if (lttng_kernel_use_old_abi) {
 288                 struct lttng_kernel_old_context old_ctx;
 289
 290                 memset(&old_ctx, 0, sizeof(old_ctx));
 291                 old_ctx.ctx = ctx->ctx;
 292                 /* only type that uses the union */
 293                 if (ctx->ctx == LTTNG_KERNEL_CONTEXT_PERF_CPU_COUNTER) {
 294                         old_ctx.u.perf_counter.type =
 295                                 ctx->u.perf_counter.type;
 296                         old_ctx.u.perf_counter.config =
 297                                 ctx->u.perf_counter.config;
 298                         memcpy(old_ctx.u.perf_counter.name,
 299                                 ctx->u.perf_counter.name,
 300                                 sizeof(old_ctx.u.perf_counter.name));
 301                 }
 302                 return LTTNG_IOCTL_CHECK(fd, LTTNG_KERNEL_OLD_CONTEXT, &old_ctx);
 303         }
 304         return LTTNG_IOCTL_CHECK(fd, LTTNG_KERNEL_CONTEXT, ctx);
 305 }
 306
 307
 308 /* Enable event, channel and session LTTNG_IOCTL_CHECK */
 309 int kernctl_enable(int fd)
 310 {
 311         return compat_ioctl_no_arg(fd, LTTNG_KERNEL_OLD_ENABLE,
 312                         LTTNG_KERNEL_ENABLE);
 313 }
 314
 315 /* Disable event, channel and session LTTNG_IOCTL_CHECK */
 316 int kernctl_disable(int fd)
 317 {
 318         return compat_ioctl_no_arg(fd, LTTNG_KERNEL_OLD_DISABLE,
 319                         LTTNG_KERNEL_DISABLE);
 320 }
 321
 322 int kernctl_start_session(int fd)
 323 {
 324         return compat_ioctl_no_arg(fd, LTTNG_KERNEL_OLD_SESSION_START,
 325                         LTTNG_KERNEL_SESSION_START);
 326 }
 327
 328 int kernctl_stop_session(int fd)
 329 {
 330         return compat_ioctl_no_arg(fd, LTTNG_KERNEL_OLD_SESSION_STOP,
 331                         LTTNG_KERNEL_SESSION_STOP);
 332 }
 333
 334 int kernctl_filter(int fd, struct lttng_filter_bytecode *filter)
 335 {
 336         struct lttng_kernel_filter_bytecode *kb;
 337         uint32_t len;
 338         int ret;
 339
 340         /* Translate bytecode to kernel bytecode */
 341         kb = zmalloc(sizeof(*kb) + filter->len);
 342         if (!kb)
 343                 return -ENOMEM;
 344         kb->len = len = filter->len;
 345         kb->reloc_offset = filter->reloc_table_offset;
 346         kb->seqnum = filter->seqnum;
 347         memcpy(kb->data, filter->data, len);
 348         ret = LTTNG_IOCTL_CHECK(fd, LTTNG_KERNEL_FILTER, kb);
 349         free(kb);
 350         return ret;
 351 }
 352
 353 int kernctl_tracepoint_list(int fd)
 354 {
 355         return compat_ioctl_no_arg(fd, LTTNG_KERNEL_OLD_TRACEPOINT_LIST,
 356                         LTTNG_KERNEL_TRACEPOINT_LIST);
 357 }
 358
 359 int kernctl_syscall_list(int fd)
 360 {
 361         return LTTNG_IOCTL_NO_CHECK(fd, LTTNG_KERNEL_SYSCALL_LIST);
 362 }
 363
 364 int kernctl_tracer_version(int fd, struct lttng_kernel_tracer_version *v)
 365 {
 366         int ret;
 367
 368         if (lttng_kernel_use_old_abi == -1) {
 369                 ret = LTTNG_IOCTL_CHECK(fd, LTTNG_KERNEL_TRACER_VERSION, v);
 370                 if (!ret) {
 371                         lttng_kernel_use_old_abi = 0;
 372                         goto end;
 373                 }
 374                 lttng_kernel_use_old_abi = 1;
 375         }
 376         if (lttng_kernel_use_old_abi) {
 377                 struct lttng_kernel_old_tracer_version old_v;
 378
 379                 ret = LTTNG_IOCTL_CHECK(fd, LTTNG_KERNEL_OLD_TRACER_VERSION, &old_v);
 380                 if (ret) {
 381                         goto end;
 382                 }
 383                 v->major = old_v.major;
 384                 v->minor = old_v.minor;
 385                 v->patchlevel = old_v.patchlevel;
 386         } else {
 387                 ret = LTTNG_IOCTL_CHECK(fd, LTTNG_KERNEL_TRACER_VERSION, v);
 388         }
 389
 390 end:
 391         return ret;
 392 }
 393
 394 int kernctl_tracer_abi_version(int fd,
 395                 struct lttng_kernel_tracer_abi_version *v)
 396 {
 397         return LTTNG_IOCTL_CHECK(fd, LTTNG_KERNEL_TRACER_ABI_VERSION, v);
 398 }
 399
 400 int kernctl_wait_quiescent(int fd)
 401 {
 402         return compat_ioctl_no_arg(fd, LTTNG_KERNEL_OLD_WAIT_QUIESCENT,
 403                         LTTNG_KERNEL_WAIT_QUIESCENT);
 404 }
 405
 406 int kernctl_buffer_flush(int fd)
 407 {
 408         return LTTNG_IOCTL_CHECK(fd, RING_BUFFER_FLUSH);
 409 }
 410
 411 int kernctl_buffer_flush_empty(int fd)
 412 {
 413         return LTTNG_IOCTL_CHECK(fd, RING_BUFFER_FLUSH_EMPTY);
 414 }
 415
 416 /* returns the version of the metadata. */
 417 int kernctl_get_metadata_version(int fd, uint64_t *version)
 418 {
 419         return LTTNG_IOCTL_CHECK(fd, RING_BUFFER_GET_METADATA_VERSION, version);
 420 }
 421
 422
 423 /* Buffer operations */
 424
 425 /* For mmap mode, readable without "get" operation */
 426
 427 /* returns the length to mmap. */
 428 int kernctl_get_mmap_len(int fd, unsigned long *len)
 429 {
 430         return LTTNG_IOCTL_CHECK(fd, RING_BUFFER_GET_MMAP_LEN, len);
 431 }
 432
 433 /* returns the maximum size for sub-buffers. */
 434 int kernctl_get_max_subbuf_size(int fd, unsigned long *len)
 435 {
 436         return LTTNG_IOCTL_CHECK(fd, RING_BUFFER_GET_MAX_SUBBUF_SIZE, len);
 437 }
 438
 439 /*
 440  * For mmap mode, operate on the current packet (between get/put or
 441  * get_next/put_next).
 442  */
 443
 444 /* returns the offset of the subbuffer belonging to the mmap reader. */
 445 int kernctl_get_mmap_read_offset(int fd, unsigned long *off)
 446 {
 447         return LTTNG_IOCTL_CHECK(fd, RING_BUFFER_GET_MMAP_READ_OFFSET, off);
 448 }
 449
 450 /* returns the size of the current sub-buffer, without padding (for mmap). */
 451 int kernctl_get_subbuf_size(int fd, unsigned long *len)
 452 {
 453         return LTTNG_IOCTL_CHECK(fd, RING_BUFFER_GET_SUBBUF_SIZE, len);
 454 }
 455
 456 /* returns the size of the current sub-buffer, without padding (for mmap). */
 457 int kernctl_get_padded_subbuf_size(int fd, unsigned long *len)
 458 {
 459         return LTTNG_IOCTL_CHECK(fd, RING_BUFFER_GET_PADDED_SUBBUF_SIZE, len);
 460 }
 461
 462 /* Get exclusive read access to the next sub-buffer that can be read. */
 463 int kernctl_get_next_subbuf(int fd)
 464 {
 465         return LTTNG_IOCTL_CHECK(fd, RING_BUFFER_GET_NEXT_SUBBUF);
 466 }
 467
 468
 469 /* Release exclusive sub-buffer access, move consumer forward. */
 470 int kernctl_put_next_subbuf(int fd)
 471 {
 472         return LTTNG_IOCTL_CHECK(fd, RING_BUFFER_PUT_NEXT_SUBBUF);
 473 }
 474
 475 /* snapshot */
 476
 477 /* Get a snapshot of the current ring buffer producer and consumer positions */
 478 int kernctl_snapshot(int fd)
 479 {
 480         return LTTNG_IOCTL_CHECK(fd, RING_BUFFER_SNAPSHOT);
 481 }
 482
 483 /*
 484  * Get a snapshot of the current ring buffer producer and consumer positions,
 485  * regardless of whether or not the two positions are contained within the
 486  * same sub-buffer.
 487  */
 488 int kernctl_snapshot_sample_positions(int fd)
 489 {
 490         return LTTNG_IOCTL_CHECK(fd, RING_BUFFER_SNAPSHOT_SAMPLE_POSITIONS);
 491 }
 492
 493 /* Get the consumer position (iteration start) */
 494 int kernctl_snapshot_get_consumed(int fd, unsigned long *pos)
 495 {
 496         return LTTNG_IOCTL_CHECK(fd, RING_BUFFER_SNAPSHOT_GET_CONSUMED, pos);
 497 }
 498
 499 /* Get the producer position (iteration end) */
 500 int kernctl_snapshot_get_produced(int fd, unsigned long *pos)
 501 {
 502         return LTTNG_IOCTL_CHECK(fd, RING_BUFFER_SNAPSHOT_GET_PRODUCED, pos);
 503 }
 504
 505 /* Get exclusive read access to the specified sub-buffer position */
 506 int kernctl_get_subbuf(int fd, unsigned long *len)
 507 {
 508         return LTTNG_IOCTL_CHECK(fd, RING_BUFFER_GET_SUBBUF, len);
 509 }
 510
 511 /* Release exclusive sub-buffer access */
 512 int kernctl_put_subbuf(int fd)
 513 {
 514         return LTTNG_IOCTL_CHECK(fd, RING_BUFFER_PUT_SUBBUF);
 515 }
 516
 517 /* Returns the timestamp begin of the current sub-buffer. */
 518 int kernctl_get_timestamp_begin(int fd, uint64_t *timestamp_begin)
 519 {
 520         return LTTNG_IOCTL_CHECK(fd, LTTNG_RING_BUFFER_GET_TIMESTAMP_BEGIN,
 521                         timestamp_begin);
 522 }
 523
 524 /* Returns the timestamp end of the current sub-buffer. */
 525 int kernctl_get_timestamp_end(int fd, uint64_t *timestamp_end)
 526 {
 527         return LTTNG_IOCTL_CHECK(fd, LTTNG_RING_BUFFER_GET_TIMESTAMP_END,
 528                         timestamp_end);
 529 }
 530
 531 /* Returns the number of discarded events in the current sub-buffer. */
 532 int kernctl_get_events_discarded(int fd, uint64_t *events_discarded)
 533 {
 534         return LTTNG_IOCTL_CHECK(fd, LTTNG_RING_BUFFER_GET_EVENTS_DISCARDED,
 535                         events_discarded);
 536 }
 537
 538 /* Returns the content size in the current sub-buffer. */
 539 int kernctl_get_content_size(int fd, uint64_t *content_size)
 540 {
 541         return LTTNG_IOCTL_CHECK(fd, LTTNG_RING_BUFFER_GET_CONTENT_SIZE,
 542                         content_size);
 543 }
 544
 545 /* Returns the packet size in the current sub-buffer. */
 546 int kernctl_get_packet_size(int fd, uint64_t *packet_size)
 547 {
 548         return LTTNG_IOCTL_CHECK(fd, LTTNG_RING_BUFFER_GET_PACKET_SIZE,
 549                         packet_size);
 550 }
 551
 552 /* Returns the stream id of the current sub-buffer. */
 553 int kernctl_get_stream_id(int fd, uint64_t *stream_id)
 554 {
 555         return LTTNG_IOCTL_CHECK(fd, LTTNG_RING_BUFFER_GET_STREAM_ID,
 556                         stream_id);
 557 }
 558
 559 /* Returns the current timestamp. */
 560 int kernctl_get_current_timestamp(int fd, uint64_t *ts)
 561 {
 562         return LTTNG_IOCTL_CHECK(fd, LTTNG_RING_BUFFER_GET_CURRENT_TIMESTAMP,
 563                         ts);
 564 }
 565
 566 /* Returns the packet sequence number of the current sub-buffer. */
 567 int kernctl_get_sequence_number(int fd, uint64_t *seq)
 568 {
 569         return LTTNG_IOCTL_CHECK(fd, LTTNG_RING_BUFFER_GET_SEQ_NUM, seq);
 570 }
 571
 572 /* Returns the stream instance id. */
 573 int kernctl_get_instance_id(int fd, uint64_t *id)
 574 {
 575         return LTTNG_IOCTL_CHECK(fd, LTTNG_RING_BUFFER_INSTANCE_ID, id);
 576 }