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_PERF_COUNTER:
 163                 context_param.u.perf_counter.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 164                 return lttng_add_perf_counter_to_ctx(context_param.u.perf_counter.type,
 165                                 context_param.u.perf_counter.config,
 166                                 context_param.u.perf_counter.name,
 167                                 ctx);
 168         case LTTNG_KERNEL_CONTEXT_COMM:
 169                 return lttng_add_comm_to_ctx(ctx);
 170         default:
 171                 return -EINVAL;
 172         }
 173 }
 174
 175 /**
 176  *      lttng_ioctl - lttng syscall through ioctl
 177  *
 178  *      @file: the file
 179  *      @cmd: the command
 180  *      @arg: command arg
 181  *
 182  *      This ioctl implements lttng commands:
 183  *      LTTNG_KERNEL_SESSION
 184  *              Returns a LTTng trace session file descriptor
 185  *      LTTNG_KERNEL_TRACER_VERSION
 186  *              Returns the LTTng kernel tracer version
 187  *      LTTNG_KERNEL_TRACEPOINT_LIST
 188  *              Returns a file descriptor listing available tracepoints
 189  *
 190  * The returned session will be deleted when its file descriptor is closed.
 191  */
 192 static
 193 long lttng_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 194 {
 195         switch (cmd) {
 196         case LTTNG_KERNEL_SESSION:
 197                 return lttng_abi_create_session();
 198         case LTTNG_KERNEL_TRACER_VERSION:
 199                 return lttng_abi_tracer_version(file,
 200                                 (struct lttng_kernel_tracer_version __user *) arg);
 201         case LTTNG_KERNEL_TRACEPOINT_LIST:
 202                 return lttng_abi_tracepoint_list();
 203         default:
 204                 return -ENOIOCTLCMD;
 205         }
 206 }
 207
 208 static const struct file_operations lttng_fops = {
 209         .unlocked_ioctl = lttng_ioctl,
 210 #ifdef CONFIG_COMPAT
 211         .compat_ioctl = lttng_ioctl,
 212 #endif
 213 };
 214
 215 /*
 216  * We tolerate no failure in this function (if one happens, we print a dmesg
 217  * error, but cannot return any error, because the channel information is
 218  * invariant.
 219  */
 220 static
 221 void lttng_metadata_create_events(struct file *channel_file)
 222 {
 223         struct ltt_channel *channel = channel_file->private_data;
 224         static struct lttng_kernel_event metadata_params = {
 225                 .instrumentation = LTTNG_KERNEL_TRACEPOINT,
 226                 .name = "lttng_metadata",
 227         };
 228         struct ltt_event *event;
 229         int ret;
 230
 231         /*
 232          * We tolerate no failure path after event creation. It will stay
 233          * invariant for the rest of the session.
 234          */
 235         event = ltt_event_create(channel, &metadata_params, NULL);
 236         if (!event) {
 237                 ret = -EINVAL;
 238                 goto create_error;
 239         }
 240         return;
 241
 242 create_error:
 243         WARN_ON(1);
 244         return;         /* not allowed to return error */
 245 }
 246
 247 static
 248 int lttng_abi_create_channel(struct file *session_file,
 249                              struct lttng_kernel_channel __user *uchan_param,
 250                              enum channel_type channel_type)
 251 {
 252         struct ltt_session *session = session_file->private_data;
 253         const struct file_operations *fops;
 254         const char *transport_name;
 255         struct ltt_channel *chan;
 256         struct file *chan_file;
 257         struct lttng_kernel_channel chan_param;
 258         int chan_fd;
 259         int ret = 0;
 260
 261         if (copy_from_user(&chan_param, uchan_param, sizeof(chan_param)))
 262                 return -EFAULT;
 263         chan_fd = get_unused_fd();
 264         if (chan_fd < 0) {
 265                 ret = chan_fd;
 266                 goto fd_error;
 267         }
 268         chan_file = anon_inode_getfile("[lttng_channel]",
 269                                        &lttng_channel_fops,
 270                                        NULL, O_RDWR);
 271         if (IS_ERR(chan_file)) {
 272                 ret = PTR_ERR(chan_file);
 273                 goto file_error;
 274         }
 275         switch (channel_type) {
 276         case PER_CPU_CHANNEL:
 277                 transport_name = chan_param.overwrite ?
 278                         "relay-overwrite" : "relay-discard";
 279                 fops = &lttng_channel_fops;
 280                 break;
 281         case METADATA_CHANNEL:
 282                 transport_name = "relay-metadata";
 283                 fops = &lttng_metadata_fops;
 284                 break;
 285         default:
 286                 transport_name = "<unknown>";
 287                 break;
 288         }
 289         /*
 290          * We tolerate no failure path after channel creation. It will stay
 291          * invariant for the rest of the session.
 292          */
 293         chan = ltt_channel_create(session, transport_name, NULL,
 294                                   chan_param.subbuf_size,
 295                                   chan_param.num_subbuf,
 296                                   chan_param.switch_timer_interval,
 297                                   chan_param.read_timer_interval);
 298         if (!chan) {
 299                 ret = -EINVAL;
 300                 goto chan_error;
 301         }
 302         chan->file = chan_file;
 303         chan_file->private_data = chan;
 304         fd_install(chan_fd, chan_file);
 305         if (channel_type == METADATA_CHANNEL) {
 306                 session->metadata = chan;
 307                 lttng_metadata_create_events(chan_file);
 308         }
 309
 310         /* The channel created holds a reference on the session */
 311         atomic_long_inc(&session_file->f_count);
 312
 313         return chan_fd;
 314
 315 chan_error:
 316         fput(chan_file);
 317 file_error:
 318         put_unused_fd(chan_fd);
 319 fd_error:
 320         return ret;
 321 }
 322
 323 /**
 324  *      lttng_session_ioctl - lttng session fd ioctl
 325  *
 326  *      @file: the file
 327  *      @cmd: the command
 328  *      @arg: command arg
 329  *
 330  *      This ioctl implements lttng commands:
 331  *      LTTNG_KERNEL_CHANNEL
 332  *              Returns a LTTng channel file descriptor
 333  *      LTTNG_KERNEL_ENABLE
 334  *              Enables tracing for a session (weak enable)
 335  *      LTTNG_KERNEL_DISABLE
 336  *              Disables tracing for a session (strong disable)
 337  *      LTTNG_KERNEL_METADATA
 338  *              Returns a LTTng metadata file descriptor
 339  *
 340  * The returned channel will be deleted when its file descriptor is closed.
 341  */
 342 static
 343 long lttng_session_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 344 {
 345         struct ltt_session *session = file->private_data;
 346
 347         switch (cmd) {
 348         case LTTNG_KERNEL_CHANNEL:
 349                 return lttng_abi_create_channel(file,
 350                                 (struct lttng_kernel_channel __user *) arg,
 351                                 PER_CPU_CHANNEL);
 352         case LTTNG_KERNEL_SESSION_START:
 353         case LTTNG_KERNEL_ENABLE:
 354                 return ltt_session_enable(session);
 355         case LTTNG_KERNEL_SESSION_STOP:
 356         case LTTNG_KERNEL_DISABLE:
 357                 return ltt_session_disable(session);
 358         case LTTNG_KERNEL_METADATA:
 359                 return lttng_abi_create_channel(file,
 360                                 (struct lttng_kernel_channel __user *) arg,
 361                                 METADATA_CHANNEL);
 362         default:
 363                 return -ENOIOCTLCMD;
 364         }
 365 }
 366
 367 /*
 368  * Called when the last file reference is dropped.
 369  *
 370  * Big fat note: channels and events are invariant for the whole session after
 371  * their creation. So this session destruction also destroys all channel and
 372  * event structures specific to this session (they are not destroyed when their
 373  * individual file is released).
 374  */
 375 static
 376 int lttng_session_release(struct inode *inode, struct file *file)
 377 {
 378         struct ltt_session *session = file->private_data;
 379
 380         if (session)
 381                 ltt_session_destroy(session);
 382         return 0;
 383 }
 384
 385 static const struct file_operations lttng_session_fops = {
 386         .release = lttng_session_release,
 387         .unlocked_ioctl = lttng_session_ioctl,
 388 #ifdef CONFIG_COMPAT
 389         .compat_ioctl = lttng_session_ioctl,
 390 #endif
 391 };
 392
 393 static
 394 int lttng_abi_open_stream(struct file *channel_file)
 395 {
 396         struct ltt_channel *channel = channel_file->private_data;
 397         struct lib_ring_buffer *buf;
 398         int stream_fd, ret;
 399         struct file *stream_file;
 400
 401         buf = channel->ops->buffer_read_open(channel->chan);
 402         if (!buf)
 403                 return -ENOENT;
 404
 405         stream_fd = get_unused_fd();
 406         if (stream_fd < 0) {
 407                 ret = stream_fd;
 408                 goto fd_error;
 409         }
 410         stream_file = anon_inode_getfile("[lttng_stream]",
 411                                          &lib_ring_buffer_file_operations,
 412                                          buf, O_RDWR);
 413         if (IS_ERR(stream_file)) {
 414                 ret = PTR_ERR(stream_file);
 415                 goto file_error;
 416         }
 417         /*
 418          * OPEN_FMODE, called within anon_inode_getfile/alloc_file, don't honor
 419          * FMODE_LSEEK, FMODE_PREAD nor FMODE_PWRITE. We need to read from this
 420          * file descriptor, so we set FMODE_PREAD here.
 421          */
 422         stream_file->f_mode |= FMODE_PREAD;
 423         fd_install(stream_fd, stream_file);
 424         /*
 425          * The stream holds a reference to the channel within the generic ring
 426          * buffer library, so no need to hold a refcount on the channel and
 427          * session files here.
 428          */
 429         return stream_fd;
 430
 431 file_error:
 432         put_unused_fd(stream_fd);
 433 fd_error:
 434         channel->ops->buffer_read_close(buf);
 435         return ret;
 436 }
 437
 438 static
 439 int lttng_abi_create_event(struct file *channel_file,
 440                            struct lttng_kernel_event __user *uevent_param)
 441 {
 442         struct ltt_channel *channel = channel_file->private_data;
 443         struct ltt_event *event;
 444         struct lttng_kernel_event event_param;
 445         int event_fd, ret;
 446         struct file *event_file;
 447
 448         if (copy_from_user(&event_param, uevent_param, sizeof(event_param)))
 449                 return -EFAULT;
 450         event_param.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 451         switch (event_param.instrumentation) {
 452         case LTTNG_KERNEL_KPROBE:
 453                 event_param.u.kprobe.symbol_name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 454                 break;
 455         case LTTNG_KERNEL_FUNCTION:
 456                 event_param.u.ftrace.symbol_name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 457                 break;
 458         default:
 459                 break;
 460         }
 461         event_fd = get_unused_fd();
 462         if (event_fd < 0) {
 463                 ret = event_fd;
 464                 goto fd_error;
 465         }
 466         event_file = anon_inode_getfile("[lttng_event]",
 467                                         &lttng_event_fops,
 468                                         NULL, O_RDWR);
 469         if (IS_ERR(event_file)) {
 470                 ret = PTR_ERR(event_file);
 471                 goto file_error;
 472         }
 473         /*
 474          * We tolerate no failure path after event creation. It will stay
 475          * invariant for the rest of the session.
 476          */
 477         event = ltt_event_create(channel, &event_param, NULL);
 478         if (!event) {
 479                 ret = -EINVAL;
 480                 goto event_error;
 481         }
 482         event_file->private_data = event;
 483         fd_install(event_fd, event_file);
 484         /* The event holds a reference on the channel */
 485         atomic_long_inc(&channel_file->f_count);
 486         return event_fd;
 487
 488 event_error:
 489         fput(event_file);
 490 file_error:
 491         put_unused_fd(event_fd);
 492 fd_error:
 493         return ret;
 494 }
 495
 496 /**
 497  *      lttng_channel_ioctl - lttng syscall through ioctl
 498  *
 499  *      @file: the file
 500  *      @cmd: the command
 501  *      @arg: command arg
 502  *
 503  *      This ioctl implements lttng commands:
 504  *      LTTNG_KERNEL_STREAM
 505  *              Returns an event stream file descriptor or failure.
 506  *              (typically, one event stream records events from one CPU)
 507  *      LTTNG_KERNEL_EVENT
 508  *              Returns an event file descriptor or failure.
 509  *      LTTNG_KERNEL_CONTEXT
 510  *              Prepend a context field to each event in the channel
 511  *      LTTNG_KERNEL_ENABLE
 512  *              Enable recording for events in this channel (weak enable)
 513  *      LTTNG_KERNEL_DISABLE
 514  *              Disable recording for events in this channel (strong disable)
 515  *
 516  * Channel and event file descriptors also hold a reference on the session.
 517  */
 518 static
 519 long lttng_channel_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 520 {
 521         struct ltt_channel *channel = file->private_data;
 522
 523         switch (cmd) {
 524         case LTTNG_KERNEL_STREAM:
 525                 return lttng_abi_open_stream(file);
 526         case LTTNG_KERNEL_EVENT:
 527                 return lttng_abi_create_event(file, (struct lttng_kernel_event __user *) arg);
 528         case LTTNG_KERNEL_CONTEXT:
 529                 return lttng_abi_add_context(file,
 530                                 (struct lttng_kernel_context __user *) arg,
 531                                 &channel->ctx, channel->session);
 532         case LTTNG_KERNEL_ENABLE:
 533                 return ltt_channel_enable(channel);
 534         case LTTNG_KERNEL_DISABLE:
 535                 return ltt_channel_disable(channel);
 536         default:
 537                 return -ENOIOCTLCMD;
 538         }
 539 }
 540
 541 /**
 542  *      lttng_metadata_ioctl - lttng syscall through ioctl
 543  *
 544  *      @file: the file
 545  *      @cmd: the command
 546  *      @arg: command arg
 547  *
 548  *      This ioctl implements lttng commands:
 549  *      LTTNG_KERNEL_STREAM
 550  *              Returns an event stream file descriptor or failure.
 551  *
 552  * Channel and event file descriptors also hold a reference on the session.
 553  */
 554 static
 555 long lttng_metadata_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 556 {
 557         switch (cmd) {
 558         case LTTNG_KERNEL_STREAM:
 559                 return lttng_abi_open_stream(file);
 560         default:
 561                 return -ENOIOCTLCMD;
 562         }
 563 }
 564
 565 /**
 566  *      lttng_channel_poll - lttng stream addition/removal monitoring
 567  *
 568  *      @file: the file
 569  *      @wait: poll table
 570  */
 571 unsigned int lttng_channel_poll(struct file *file, poll_table *wait)
 572 {
 573         struct ltt_channel *channel = file->private_data;
 574         unsigned int mask = 0;
 575
 576         if (file->f_mode & FMODE_READ) {
 577                 poll_wait_set_exclusive(wait);
 578                 poll_wait(file, channel->ops->get_hp_wait_queue(channel->chan),
 579                           wait);
 580
 581                 if (channel->ops->is_disabled(channel->chan))
 582                         return POLLERR;
 583                 if (channel->ops->is_finalized(channel->chan))
 584                         return POLLHUP;
 585                 else
 586                         return POLLIN | POLLRDNORM;
 587         }
 588         return mask;
 589
 590 }
 591
 592 static
 593 int lttng_channel_release(struct inode *inode, struct file *file)
 594 {
 595         struct ltt_channel *channel = file->private_data;
 596
 597         if (channel)
 598                 fput(channel->session->file);
 599         return 0;
 600 }
 601
 602 static const struct file_operations lttng_channel_fops = {
 603         .release = lttng_channel_release,
 604         .poll = lttng_channel_poll,
 605         .unlocked_ioctl = lttng_channel_ioctl,
 606 #ifdef CONFIG_COMPAT
 607         .compat_ioctl = lttng_channel_ioctl,
 608 #endif
 609 };
 610
 611 static const struct file_operations lttng_metadata_fops = {
 612         .release = lttng_channel_release,
 613         .unlocked_ioctl = lttng_metadata_ioctl,
 614 #ifdef CONFIG_COMPAT
 615         .compat_ioctl = lttng_metadata_ioctl,
 616 #endif
 617 };
 618
 619 /**
 620  *      lttng_event_ioctl - lttng syscall through ioctl
 621  *
 622  *      @file: the file
 623  *      @cmd: the command
 624  *      @arg: command arg
 625  *
 626  *      This ioctl implements lttng commands:
 627  *      LTTNG_KERNEL_CONTEXT
 628  *              Prepend a context field to each record of this event
 629  *      LTTNG_KERNEL_ENABLE
 630  *              Enable recording for this event (weak enable)
 631  *      LTTNG_KERNEL_DISABLE
 632  *              Disable recording for this event (strong disable)
 633  */
 634 static
 635 long lttng_event_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 636 {
 637         struct ltt_event *event = file->private_data;
 638
 639         switch (cmd) {
 640         case LTTNG_KERNEL_CONTEXT:
 641                 return lttng_abi_add_context(file,
 642                                 (struct lttng_kernel_context __user *) arg,
 643                                 &event->ctx, event->chan->session);
 644         case LTTNG_KERNEL_ENABLE:
 645                 return ltt_event_enable(event);
 646         case LTTNG_KERNEL_DISABLE:
 647                 return ltt_event_disable(event);
 648         default:
 649                 return -ENOIOCTLCMD;
 650         }
 651 }
 652
 653 static
 654 int lttng_event_release(struct inode *inode, struct file *file)
 655 {
 656         struct ltt_event *event = file->private_data;
 657
 658         if (event)
 659                 fput(event->chan->file);
 660         return 0;
 661 }
 662
 663 /* TODO: filter control ioctl */
 664 static const struct file_operations lttng_event_fops = {
 665         .release = lttng_event_release,
 666         .unlocked_ioctl = lttng_event_ioctl,
 667 #ifdef CONFIG_COMPAT
 668         .compat_ioctl = lttng_event_ioctl,
 669 #endif
 670 };
 671
 672 int __init ltt_debugfs_abi_init(void)
 673 {
 674         int ret = 0;
 675
 676         wrapper_vmalloc_sync_all();
 677         lttng_dentry = debugfs_create_file("lttng", S_IWUSR, NULL, NULL,
 678                                            &lttng_fops);
 679         if (IS_ERR(lttng_dentry) || !lttng_dentry) {
 680                 printk(KERN_ERR "Error creating LTTng control file\n");
 681                 ret = -ENOMEM;
 682                 goto error;
 683         }
 684 error:
 685         return ret;
 686 }
 687
 688 void __exit ltt_debugfs_abi_exit(void)
 689 {
 690         debugfs_remove(lttng_dentry);
 691 }