ltt-debugfs-abi.c

   1 /*
   2  * ltt-debugfs-abi.c
   3  *
   4  * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * LTTng debugfs ABI
   7  *
   8  * Mimic system calls for:
   9  * - session creation, returns a file descriptor or failure.
  10  *   - channel creation, returns a file descriptor or failure.
  11  *     - Operates on a session file descriptor
  12  *     - Takes all channel options as parameters.
  13  *   - stream get, returns a file descriptor or failure.
  14  *     - Operates on a channel file descriptor.
  15  *   - stream notifier get, returns a file descriptor or failure.
  16  *     - Operates on a channel file descriptor.
  17  *   - event creation, returns a file descriptor or failure.
  18  *     - Operates on a channel file descriptor
  19  *     - Takes an event name as parameter
  20  *     - Takes an instrumentation source as parameter
  21  *       - e.g. tracepoints, dynamic_probes...
  22  *     - Takes instrumentation source specific arguments.
  23  *
  24  * Dual LGPL v2.1/GPL v2 license.
  25  */
  26
  27 #include <linux/module.h>
  28 #include <linux/debugfs.h>
  29 #include <linux/anon_inodes.h>
  30 #include <linux/file.h>
  31 #include <linux/uaccess.h>
  32 #include <linux/slab.h>
  33 #include "wrapper/vmalloc.h"    /* for wrapper_vmalloc_sync_all() */
  34 #include "wrapper/ringbuffer/vfs.h"
  35 #include "wrapper/poll.h"
  36 #include "ltt-debugfs-abi.h"
  37 #include "ltt-events.h"
  38 #include "ltt-tracer.h"
  39
  40 /*
  41  * This is LTTng's own personal way to create a system call as an external
  42  * module. We use ioctl() on /sys/kernel/debug/lttng.
  43  */
  44
  45 static struct dentry *lttng_dentry;
  46 static const struct file_operations lttng_fops;
  47 static const struct file_operations lttng_session_fops;
  48 static const struct file_operations lttng_channel_fops;
  49 static const struct file_operations lttng_metadata_fops;
  50 static const struct file_operations lttng_event_fops;
  51
  52 enum channel_type {
  53         PER_CPU_CHANNEL,
  54         METADATA_CHANNEL,
  55 };
  56
  57 static
  58 int lttng_abi_create_session(void)
  59 {
  60         struct ltt_session *session;
  61         struct file *session_file;
  62         int session_fd, ret;
  63
  64         session = ltt_session_create();
  65         if (!session)
  66                 return -ENOMEM;
  67         session_fd = get_unused_fd();
  68         if (session_fd < 0) {
  69                 ret = session_fd;
  70                 goto fd_error;
  71         }
  72         session_file = anon_inode_getfile("[lttng_session]",
  73                                           &lttng_session_fops,
  74                                           session, O_RDWR);
  75         if (IS_ERR(session_file)) {
  76                 ret = PTR_ERR(session_file);
  77                 goto file_error;
  78         }
  79         session->file = session_file;
  80         fd_install(session_fd, session_file);
  81         return session_fd;
  82
  83 file_error:
  84         put_unused_fd(session_fd);
  85 fd_error:
  86         ltt_session_destroy(session);
  87         return ret;
  88 }
  89
  90 static
  91 int lttng_abi_tracepoint_list(void)
  92 {
  93         struct file *tracepoint_list_file;
  94         int file_fd, ret;
  95
  96         file_fd = get_unused_fd();
  97         if (file_fd < 0) {
  98                 ret = file_fd;
  99                 goto fd_error;
 100         }
 101
 102         tracepoint_list_file = anon_inode_getfile("[lttng_session]",
 103                                           &lttng_tracepoint_list_fops,
 104                                           NULL, O_RDWR);
 105         if (IS_ERR(tracepoint_list_file)) {
 106                 ret = PTR_ERR(tracepoint_list_file);
 107                 goto file_error;
 108         }
 109         ret = lttng_tracepoint_list_fops.open(NULL, tracepoint_list_file);
 110         if (ret < 0)
 111                 goto open_error;
 112         fd_install(file_fd, tracepoint_list_file);
 113         if (file_fd < 0) {
 114                 ret = file_fd;
 115                 goto fd_error;
 116         }
 117         return file_fd;
 118
 119 open_error:
 120         fput(tracepoint_list_file);
 121 file_error:
 122         put_unused_fd(file_fd);
 123 fd_error:
 124         return ret;
 125 }
 126
 127 static
 128 long lttng_abi_tracer_version(struct file *file,
 129         struct lttng_kernel_tracer_version __user *uversion_param)
 130 {
 131         struct lttng_kernel_tracer_version v;
 132
 133         v.version = LTTNG_VERSION;
 134         v.patchlevel = LTTNG_PATCHLEVEL;
 135         v.sublevel = LTTNG_SUBLEVEL;
 136
 137         if (copy_to_user(uversion_param, &v, sizeof(v)))
 138                 return -EFAULT;
 139         return 0;
 140 }
 141
 142 static
 143 long lttng_abi_add_context(struct file *file,
 144         struct lttng_kernel_context __user *ucontext_param,
 145         struct lttng_ctx **ctx, struct ltt_session *session)
 146 {
 147         struct lttng_kernel_context context_param;
 148
 149         if (session->been_active)
 150                 return -EPERM;
 151
 152         if (copy_from_user(&context_param, ucontext_param, sizeof(context_param)))
 153                 return -EFAULT;
 154
 155         switch (context_param.ctx) {
 156         case LTTNG_KERNEL_CONTEXT_PID:
 157                 return lttng_add_pid_to_ctx(ctx);
 158         case LTTNG_KERNEL_CONTEXT_PRIO:
 159                 return lttng_add_prio_to_ctx(ctx);
 160         case LTTNG_KERNEL_CONTEXT_NICE:
 161                 return lttng_add_nice_to_ctx(ctx);
 162         case LTTNG_KERNEL_CONTEXT_VPID:
 163                 return lttng_add_vpid_to_ctx(ctx);
 164         case LTTNG_KERNEL_CONTEXT_TID:
 165                 return lttng_add_tid_to_ctx(ctx);
 166         case LTTNG_KERNEL_CONTEXT_VTID:
 167                 return lttng_add_vtid_to_ctx(ctx);
 168         case LTTNG_KERNEL_CONTEXT_PPID:
 169                 return lttng_add_ppid_to_ctx(ctx);
 170         case LTTNG_KERNEL_CONTEXT_VPPID:
 171                 return lttng_add_vppid_to_ctx(ctx);
 172         case LTTNG_KERNEL_CONTEXT_PERF_COUNTER:
 173                 context_param.u.perf_counter.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 174                 return lttng_add_perf_counter_to_ctx(context_param.u.perf_counter.type,
 175                                 context_param.u.perf_counter.config,
 176                                 context_param.u.perf_counter.name,
 177                                 ctx);
 178         case LTTNG_KERNEL_CONTEXT_COMM:
 179                 return lttng_add_comm_to_ctx(ctx);
 180         default:
 181                 return -EINVAL;
 182         }
 183 }
 184
 185 /**
 186  *      lttng_ioctl - lttng syscall through ioctl
 187  *
 188  *      @file: the file
 189  *      @cmd: the command
 190  *      @arg: command arg
 191  *
 192  *      This ioctl implements lttng commands:
 193  *      LTTNG_KERNEL_SESSION
 194  *              Returns a LTTng trace session file descriptor
 195  *      LTTNG_KERNEL_TRACER_VERSION
 196  *              Returns the LTTng kernel tracer version
 197  *      LTTNG_KERNEL_TRACEPOINT_LIST
 198  *              Returns a file descriptor listing available tracepoints
 199  *
 200  * The returned session will be deleted when its file descriptor is closed.
 201  */
 202 static
 203 long lttng_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 204 {
 205         switch (cmd) {
 206         case LTTNG_KERNEL_SESSION:
 207                 return lttng_abi_create_session();
 208         case LTTNG_KERNEL_TRACER_VERSION:
 209                 return lttng_abi_tracer_version(file,
 210                                 (struct lttng_kernel_tracer_version __user *) arg);
 211         case LTTNG_KERNEL_TRACEPOINT_LIST:
 212                 return lttng_abi_tracepoint_list();
 213         default:
 214                 return -ENOIOCTLCMD;
 215         }
 216 }
 217
 218 static const struct file_operations lttng_fops = {
 219         .unlocked_ioctl = lttng_ioctl,
 220 #ifdef CONFIG_COMPAT
 221         .compat_ioctl = lttng_ioctl,
 222 #endif
 223 };
 224
 225 /*
 226  * We tolerate no failure in this function (if one happens, we print a dmesg
 227  * error, but cannot return any error, because the channel information is
 228  * invariant.
 229  */
 230 static
 231 void lttng_metadata_create_events(struct file *channel_file)
 232 {
 233         struct ltt_channel *channel = channel_file->private_data;
 234         static struct lttng_kernel_event metadata_params = {
 235                 .instrumentation = LTTNG_KERNEL_TRACEPOINT,
 236                 .name = "lttng_metadata",
 237         };
 238         struct ltt_event *event;
 239         int ret;
 240
 241         /*
 242          * We tolerate no failure path after event creation. It will stay
 243          * invariant for the rest of the session.
 244          */
 245         event = ltt_event_create(channel, &metadata_params, NULL);
 246         if (!event) {
 247                 ret = -EINVAL;
 248                 goto create_error;
 249         }
 250         return;
 251
 252 create_error:
 253         WARN_ON(1);
 254         return;         /* not allowed to return error */
 255 }
 256
 257 static
 258 int lttng_abi_create_channel(struct file *session_file,
 259                              struct lttng_kernel_channel __user *uchan_param,
 260                              enum channel_type channel_type)
 261 {
 262         struct ltt_session *session = session_file->private_data;
 263         const struct file_operations *fops;
 264         const char *transport_name;
 265         struct ltt_channel *chan;
 266         struct file *chan_file;
 267         struct lttng_kernel_channel chan_param;
 268         int chan_fd;
 269         int ret = 0;
 270
 271         if (copy_from_user(&chan_param, uchan_param, sizeof(chan_param)))
 272                 return -EFAULT;
 273         chan_fd = get_unused_fd();
 274         if (chan_fd < 0) {
 275                 ret = chan_fd;
 276                 goto fd_error;
 277         }
 278         chan_file = anon_inode_getfile("[lttng_channel]",
 279                                        &lttng_channel_fops,
 280                                        NULL, O_RDWR);
 281         if (IS_ERR(chan_file)) {
 282                 ret = PTR_ERR(chan_file);
 283                 goto file_error;
 284         }
 285         switch (channel_type) {
 286         case PER_CPU_CHANNEL:
 287                 transport_name = chan_param.overwrite ?
 288                         "relay-overwrite" : "relay-discard";
 289                 fops = &lttng_channel_fops;
 290                 break;
 291         case METADATA_CHANNEL:
 292                 transport_name = "relay-metadata";
 293                 fops = &lttng_metadata_fops;
 294                 break;
 295         default:
 296                 transport_name = "<unknown>";
 297                 break;
 298         }
 299         /*
 300          * We tolerate no failure path after channel creation. It will stay
 301          * invariant for the rest of the session.
 302          */
 303         chan = ltt_channel_create(session, transport_name, NULL,
 304                                   chan_param.subbuf_size,
 305                                   chan_param.num_subbuf,
 306                                   chan_param.switch_timer_interval,
 307                                   chan_param.read_timer_interval);
 308         if (!chan) {
 309                 ret = -EINVAL;
 310                 goto chan_error;
 311         }
 312         chan->file = chan_file;
 313         chan_file->private_data = chan;
 314         fd_install(chan_fd, chan_file);
 315         if (channel_type == METADATA_CHANNEL) {
 316                 session->metadata = chan;
 317                 lttng_metadata_create_events(chan_file);
 318         }
 319
 320         /* The channel created holds a reference on the session */
 321         atomic_long_inc(&session_file->f_count);
 322
 323         return chan_fd;
 324
 325 chan_error:
 326         fput(chan_file);
 327 file_error:
 328         put_unused_fd(chan_fd);
 329 fd_error:
 330         return ret;
 331 }
 332
 333 /**
 334  *      lttng_session_ioctl - lttng session fd ioctl
 335  *
 336  *      @file: the file
 337  *      @cmd: the command
 338  *      @arg: command arg
 339  *
 340  *      This ioctl implements lttng commands:
 341  *      LTTNG_KERNEL_CHANNEL
 342  *              Returns a LTTng channel file descriptor
 343  *      LTTNG_KERNEL_ENABLE
 344  *              Enables tracing for a session (weak enable)
 345  *      LTTNG_KERNEL_DISABLE
 346  *              Disables tracing for a session (strong disable)
 347  *      LTTNG_KERNEL_METADATA
 348  *              Returns a LTTng metadata file descriptor
 349  *
 350  * The returned channel will be deleted when its file descriptor is closed.
 351  */
 352 static
 353 long lttng_session_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 354 {
 355         struct ltt_session *session = file->private_data;
 356
 357         switch (cmd) {
 358         case LTTNG_KERNEL_CHANNEL:
 359                 return lttng_abi_create_channel(file,
 360                                 (struct lttng_kernel_channel __user *) arg,
 361                                 PER_CPU_CHANNEL);
 362         case LTTNG_KERNEL_SESSION_START:
 363         case LTTNG_KERNEL_ENABLE:
 364                 return ltt_session_enable(session);
 365         case LTTNG_KERNEL_SESSION_STOP:
 366         case LTTNG_KERNEL_DISABLE:
 367                 return ltt_session_disable(session);
 368         case LTTNG_KERNEL_METADATA:
 369                 return lttng_abi_create_channel(file,
 370                                 (struct lttng_kernel_channel __user *) arg,
 371                                 METADATA_CHANNEL);
 372         default:
 373                 return -ENOIOCTLCMD;
 374         }
 375 }
 376
 377 /*
 378  * Called when the last file reference is dropped.
 379  *
 380  * Big fat note: channels and events are invariant for the whole session after
 381  * their creation. So this session destruction also destroys all channel and
 382  * event structures specific to this session (they are not destroyed when their
 383  * individual file is released).
 384  */
 385 static
 386 int lttng_session_release(struct inode *inode, struct file *file)
 387 {
 388         struct ltt_session *session = file->private_data;
 389
 390         if (session)
 391                 ltt_session_destroy(session);
 392         return 0;
 393 }
 394
 395 static const struct file_operations lttng_session_fops = {
 396         .release = lttng_session_release,
 397         .unlocked_ioctl = lttng_session_ioctl,
 398 #ifdef CONFIG_COMPAT
 399         .compat_ioctl = lttng_session_ioctl,
 400 #endif
 401 };
 402
 403 static
 404 int lttng_abi_open_stream(struct file *channel_file)
 405 {
 406         struct ltt_channel *channel = channel_file->private_data;
 407         struct lib_ring_buffer *buf;
 408         int stream_fd, ret;
 409         struct file *stream_file;
 410
 411         buf = channel->ops->buffer_read_open(channel->chan);
 412         if (!buf)
 413                 return -ENOENT;
 414
 415         stream_fd = get_unused_fd();
 416         if (stream_fd < 0) {
 417                 ret = stream_fd;
 418                 goto fd_error;
 419         }
 420         stream_file = anon_inode_getfile("[lttng_stream]",
 421                                          &lib_ring_buffer_file_operations,
 422                                          buf, O_RDWR);
 423         if (IS_ERR(stream_file)) {
 424                 ret = PTR_ERR(stream_file);
 425                 goto file_error;
 426         }
 427         /*
 428          * OPEN_FMODE, called within anon_inode_getfile/alloc_file, don't honor
 429          * FMODE_LSEEK, FMODE_PREAD nor FMODE_PWRITE. We need to read from this
 430          * file descriptor, so we set FMODE_PREAD here.
 431          */
 432         stream_file->f_mode |= FMODE_PREAD;
 433         fd_install(stream_fd, stream_file);
 434         /*
 435          * The stream holds a reference to the channel within the generic ring
 436          * buffer library, so no need to hold a refcount on the channel and
 437          * session files here.
 438          */
 439         return stream_fd;
 440
 441 file_error:
 442         put_unused_fd(stream_fd);
 443 fd_error:
 444         channel->ops->buffer_read_close(buf);
 445         return ret;
 446 }
 447
 448 static
 449 int lttng_abi_create_event(struct file *channel_file,
 450                            struct lttng_kernel_event __user *uevent_param)
 451 {
 452         struct ltt_channel *channel = channel_file->private_data;
 453         struct ltt_event *event;
 454         struct lttng_kernel_event event_param;
 455         int event_fd, ret;
 456         struct file *event_file;
 457
 458         if (copy_from_user(&event_param, uevent_param, sizeof(event_param)))
 459                 return -EFAULT;
 460         event_param.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 461         switch (event_param.instrumentation) {
 462         case LTTNG_KERNEL_KPROBE:
 463                 event_param.u.kprobe.symbol_name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 464                 break;
 465         case LTTNG_KERNEL_FUNCTION:
 466                 event_param.u.ftrace.symbol_name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 467                 break;
 468         default:
 469                 break;
 470         }
 471         event_fd = get_unused_fd();
 472         if (event_fd < 0) {
 473                 ret = event_fd;
 474                 goto fd_error;
 475         }
 476         event_file = anon_inode_getfile("[lttng_event]",
 477                                         &lttng_event_fops,
 478                                         NULL, O_RDWR);
 479         if (IS_ERR(event_file)) {
 480                 ret = PTR_ERR(event_file);
 481                 goto file_error;
 482         }
 483         /*
 484          * We tolerate no failure path after event creation. It will stay
 485          * invariant for the rest of the session.
 486          */
 487         event = ltt_event_create(channel, &event_param, NULL);
 488         if (!event) {
 489                 ret = -EINVAL;
 490                 goto event_error;
 491         }
 492         event_file->private_data = event;
 493         fd_install(event_fd, event_file);
 494         /* The event holds a reference on the channel */
 495         atomic_long_inc(&channel_file->f_count);
 496         return event_fd;
 497
 498 event_error:
 499         fput(event_file);
 500 file_error:
 501         put_unused_fd(event_fd);
 502 fd_error:
 503         return ret;
 504 }
 505
 506 /**
 507  *      lttng_channel_ioctl - lttng syscall through ioctl
 508  *
 509  *      @file: the file
 510  *      @cmd: the command
 511  *      @arg: command arg
 512  *
 513  *      This ioctl implements lttng commands:
 514  *      LTTNG_KERNEL_STREAM
 515  *              Returns an event stream file descriptor or failure.
 516  *              (typically, one event stream records events from one CPU)
 517  *      LTTNG_KERNEL_EVENT
 518  *              Returns an event file descriptor or failure.
 519  *      LTTNG_KERNEL_CONTEXT
 520  *              Prepend a context field to each event in the channel
 521  *      LTTNG_KERNEL_ENABLE
 522  *              Enable recording for events in this channel (weak enable)
 523  *      LTTNG_KERNEL_DISABLE
 524  *              Disable recording for events in this channel (strong disable)
 525  *
 526  * Channel and event file descriptors also hold a reference on the session.
 527  */
 528 static
 529 long lttng_channel_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 530 {
 531         struct ltt_channel *channel = file->private_data;
 532
 533         switch (cmd) {
 534         case LTTNG_KERNEL_STREAM:
 535                 return lttng_abi_open_stream(file);
 536         case LTTNG_KERNEL_EVENT:
 537                 return lttng_abi_create_event(file, (struct lttng_kernel_event __user *) arg);
 538         case LTTNG_KERNEL_CONTEXT:
 539                 return lttng_abi_add_context(file,
 540                                 (struct lttng_kernel_context __user *) arg,
 541                                 &channel->ctx, channel->session);
 542         case LTTNG_KERNEL_ENABLE:
 543                 return ltt_channel_enable(channel);
 544         case LTTNG_KERNEL_DISABLE:
 545                 return ltt_channel_disable(channel);
 546         default:
 547                 return -ENOIOCTLCMD;
 548         }
 549 }
 550
 551 /**
 552  *      lttng_metadata_ioctl - lttng syscall through ioctl
 553  *
 554  *      @file: the file
 555  *      @cmd: the command
 556  *      @arg: command arg
 557  *
 558  *      This ioctl implements lttng commands:
 559  *      LTTNG_KERNEL_STREAM
 560  *              Returns an event stream file descriptor or failure.
 561  *
 562  * Channel and event file descriptors also hold a reference on the session.
 563  */
 564 static
 565 long lttng_metadata_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 566 {
 567         switch (cmd) {
 568         case LTTNG_KERNEL_STREAM:
 569                 return lttng_abi_open_stream(file);
 570         default:
 571                 return -ENOIOCTLCMD;
 572         }
 573 }
 574
 575 /**
 576  *      lttng_channel_poll - lttng stream addition/removal monitoring
 577  *
 578  *      @file: the file
 579  *      @wait: poll table
 580  */
 581 unsigned int lttng_channel_poll(struct file *file, poll_table *wait)
 582 {
 583         struct ltt_channel *channel = file->private_data;
 584         unsigned int mask = 0;
 585
 586         if (file->f_mode & FMODE_READ) {
 587                 poll_wait_set_exclusive(wait);
 588                 poll_wait(file, channel->ops->get_hp_wait_queue(channel->chan),
 589                           wait);
 590
 591                 if (channel->ops->is_disabled(channel->chan))
 592                         return POLLERR;
 593                 if (channel->ops->is_finalized(channel->chan))
 594                         return POLLHUP;
 595                 else
 596                         return POLLIN | POLLRDNORM;
 597         }
 598         return mask;
 599
 600 }
 601
 602 static
 603 int lttng_channel_release(struct inode *inode, struct file *file)
 604 {
 605         struct ltt_channel *channel = file->private_data;
 606
 607         if (channel)
 608                 fput(channel->session->file);
 609         return 0;
 610 }
 611
 612 static const struct file_operations lttng_channel_fops = {
 613         .release = lttng_channel_release,
 614         .poll = lttng_channel_poll,
 615         .unlocked_ioctl = lttng_channel_ioctl,
 616 #ifdef CONFIG_COMPAT
 617         .compat_ioctl = lttng_channel_ioctl,
 618 #endif
 619 };
 620
 621 static const struct file_operations lttng_metadata_fops = {
 622         .release = lttng_channel_release,
 623         .unlocked_ioctl = lttng_metadata_ioctl,
 624 #ifdef CONFIG_COMPAT
 625         .compat_ioctl = lttng_metadata_ioctl,
 626 #endif
 627 };
 628
 629 /**
 630  *      lttng_event_ioctl - lttng syscall through ioctl
 631  *
 632  *      @file: the file
 633  *      @cmd: the command
 634  *      @arg: command arg
 635  *
 636  *      This ioctl implements lttng commands:
 637  *      LTTNG_KERNEL_CONTEXT
 638  *              Prepend a context field to each record of this event
 639  *      LTTNG_KERNEL_ENABLE
 640  *              Enable recording for this event (weak enable)
 641  *      LTTNG_KERNEL_DISABLE
 642  *              Disable recording for this event (strong disable)
 643  */
 644 static
 645 long lttng_event_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 646 {
 647         struct ltt_event *event = file->private_data;
 648
 649         switch (cmd) {
 650         case LTTNG_KERNEL_CONTEXT:
 651                 return lttng_abi_add_context(file,
 652                                 (struct lttng_kernel_context __user *) arg,
 653                                 &event->ctx, event->chan->session);
 654         case LTTNG_KERNEL_ENABLE:
 655                 return ltt_event_enable(event);
 656         case LTTNG_KERNEL_DISABLE:
 657                 return ltt_event_disable(event);
 658         default:
 659                 return -ENOIOCTLCMD;
 660         }
 661 }
 662
 663 static
 664 int lttng_event_release(struct inode *inode, struct file *file)
 665 {
 666         struct ltt_event *event = file->private_data;
 667
 668         if (event)
 669                 fput(event->chan->file);
 670         return 0;
 671 }
 672
 673 /* TODO: filter control ioctl */
 674 static const struct file_operations lttng_event_fops = {
 675         .release = lttng_event_release,
 676         .unlocked_ioctl = lttng_event_ioctl,
 677 #ifdef CONFIG_COMPAT
 678         .compat_ioctl = lttng_event_ioctl,
 679 #endif
 680 };
 681
 682 int __init ltt_debugfs_abi_init(void)
 683 {
 684         int ret = 0;
 685
 686         wrapper_vmalloc_sync_all();
 687         lttng_dentry = debugfs_create_file("lttng", S_IWUSR, NULL, NULL,
 688                                            &lttng_fops);
 689         if (IS_ERR(lttng_dentry) || !lttng_dentry) {
 690                 printk(KERN_ERR "Error creating LTTng control file\n");
 691                 ret = -ENOMEM;
 692                 goto error;
 693         }
 694 error:
 695         return ret;
 696 }
 697
 698 void __exit ltt_debugfs_abi_exit(void)
 699 {
 700         debugfs_remove(lttng_dentry);
 701 }