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  *      LTTNG_KERNEL_WAIT_QUIESCENT
 200  *              Returns after all previously running probes have completed
 201  *
 202  * The returned session will be deleted when its file descriptor is closed.
 203  */
 204 static
 205 long lttng_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 206 {
 207         switch (cmd) {
 208         case LTTNG_KERNEL_SESSION:
 209                 return lttng_abi_create_session();
 210         case LTTNG_KERNEL_TRACER_VERSION:
 211                 return lttng_abi_tracer_version(file,
 212                                 (struct lttng_kernel_tracer_version __user *) arg);
 213         case LTTNG_KERNEL_TRACEPOINT_LIST:
 214                 return lttng_abi_tracepoint_list();
 215         case LTTNG_KERNEL_WAIT_QUIESCENT:
 216                 synchronize_trace();
 217                 return 0;
 218         default:
 219                 return -ENOIOCTLCMD;
 220         }
 221 }
 222
 223 static const struct file_operations lttng_fops = {
 224         .unlocked_ioctl = lttng_ioctl,
 225 #ifdef CONFIG_COMPAT
 226         .compat_ioctl = lttng_ioctl,
 227 #endif
 228 };
 229
 230 /*
 231  * We tolerate no failure in this function (if one happens, we print a dmesg
 232  * error, but cannot return any error, because the channel information is
 233  * invariant.
 234  */
 235 static
 236 void lttng_metadata_create_events(struct file *channel_file)
 237 {
 238         struct ltt_channel *channel = channel_file->private_data;
 239         static struct lttng_kernel_event metadata_params = {
 240                 .instrumentation = LTTNG_KERNEL_TRACEPOINT,
 241                 .name = "lttng_metadata",
 242         };
 243         struct ltt_event *event;
 244         int ret;
 245
 246         /*
 247          * We tolerate no failure path after event creation. It will stay
 248          * invariant for the rest of the session.
 249          */
 250         event = ltt_event_create(channel, &metadata_params, NULL);
 251         if (!event) {
 252                 ret = -EINVAL;
 253                 goto create_error;
 254         }
 255         return;
 256
 257 create_error:
 258         WARN_ON(1);
 259         return;         /* not allowed to return error */
 260 }
 261
 262 static
 263 int lttng_abi_create_channel(struct file *session_file,
 264                              struct lttng_kernel_channel __user *uchan_param,
 265                              enum channel_type channel_type)
 266 {
 267         struct ltt_session *session = session_file->private_data;
 268         const struct file_operations *fops;
 269         const char *transport_name;
 270         struct ltt_channel *chan;
 271         struct file *chan_file;
 272         struct lttng_kernel_channel chan_param;
 273         int chan_fd;
 274         int ret = 0;
 275
 276         if (copy_from_user(&chan_param, uchan_param, sizeof(chan_param)))
 277                 return -EFAULT;
 278         chan_fd = get_unused_fd();
 279         if (chan_fd < 0) {
 280                 ret = chan_fd;
 281                 goto fd_error;
 282         }
 283         chan_file = anon_inode_getfile("[lttng_channel]",
 284                                        &lttng_channel_fops,
 285                                        NULL, O_RDWR);
 286         if (IS_ERR(chan_file)) {
 287                 ret = PTR_ERR(chan_file);
 288                 goto file_error;
 289         }
 290         switch (channel_type) {
 291         case PER_CPU_CHANNEL:
 292                 transport_name = chan_param.overwrite ?
 293                         "relay-overwrite" : "relay-discard";
 294                 fops = &lttng_channel_fops;
 295                 break;
 296         case METADATA_CHANNEL:
 297                 transport_name = "relay-metadata";
 298                 fops = &lttng_metadata_fops;
 299                 break;
 300         default:
 301                 transport_name = "<unknown>";
 302                 break;
 303         }
 304         /*
 305          * We tolerate no failure path after channel creation. It will stay
 306          * invariant for the rest of the session.
 307          */
 308         chan = ltt_channel_create(session, transport_name, NULL,
 309                                   chan_param.subbuf_size,
 310                                   chan_param.num_subbuf,
 311                                   chan_param.switch_timer_interval,
 312                                   chan_param.read_timer_interval);
 313         if (!chan) {
 314                 ret = -EINVAL;
 315                 goto chan_error;
 316         }
 317         chan->file = chan_file;
 318         chan_file->private_data = chan;
 319         fd_install(chan_fd, chan_file);
 320         if (channel_type == METADATA_CHANNEL) {
 321                 session->metadata = chan;
 322                 lttng_metadata_create_events(chan_file);
 323         }
 324
 325         /* The channel created holds a reference on the session */
 326         atomic_long_inc(&session_file->f_count);
 327
 328         return chan_fd;
 329
 330 chan_error:
 331         fput(chan_file);
 332 file_error:
 333         put_unused_fd(chan_fd);
 334 fd_error:
 335         return ret;
 336 }
 337
 338 /**
 339  *      lttng_session_ioctl - lttng session fd ioctl
 340  *
 341  *      @file: the file
 342  *      @cmd: the command
 343  *      @arg: command arg
 344  *
 345  *      This ioctl implements lttng commands:
 346  *      LTTNG_KERNEL_CHANNEL
 347  *              Returns a LTTng channel file descriptor
 348  *      LTTNG_KERNEL_ENABLE
 349  *              Enables tracing for a session (weak enable)
 350  *      LTTNG_KERNEL_DISABLE
 351  *              Disables tracing for a session (strong disable)
 352  *      LTTNG_KERNEL_METADATA
 353  *              Returns a LTTng metadata file descriptor
 354  *
 355  * The returned channel will be deleted when its file descriptor is closed.
 356  */
 357 static
 358 long lttng_session_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 359 {
 360         struct ltt_session *session = file->private_data;
 361
 362         switch (cmd) {
 363         case LTTNG_KERNEL_CHANNEL:
 364                 return lttng_abi_create_channel(file,
 365                                 (struct lttng_kernel_channel __user *) arg,
 366                                 PER_CPU_CHANNEL);
 367         case LTTNG_KERNEL_SESSION_START:
 368         case LTTNG_KERNEL_ENABLE:
 369                 return ltt_session_enable(session);
 370         case LTTNG_KERNEL_SESSION_STOP:
 371         case LTTNG_KERNEL_DISABLE:
 372                 return ltt_session_disable(session);
 373         case LTTNG_KERNEL_METADATA:
 374                 return lttng_abi_create_channel(file,
 375                                 (struct lttng_kernel_channel __user *) arg,
 376                                 METADATA_CHANNEL);
 377         default:
 378                 return -ENOIOCTLCMD;
 379         }
 380 }
 381
 382 /*
 383  * Called when the last file reference is dropped.
 384  *
 385  * Big fat note: channels and events are invariant for the whole session after
 386  * their creation. So this session destruction also destroys all channel and
 387  * event structures specific to this session (they are not destroyed when their
 388  * individual file is released).
 389  */
 390 static
 391 int lttng_session_release(struct inode *inode, struct file *file)
 392 {
 393         struct ltt_session *session = file->private_data;
 394
 395         if (session)
 396                 ltt_session_destroy(session);
 397         return 0;
 398 }
 399
 400 static const struct file_operations lttng_session_fops = {
 401         .release = lttng_session_release,
 402         .unlocked_ioctl = lttng_session_ioctl,
 403 #ifdef CONFIG_COMPAT
 404         .compat_ioctl = lttng_session_ioctl,
 405 #endif
 406 };
 407
 408 static
 409 int lttng_abi_open_stream(struct file *channel_file)
 410 {
 411         struct ltt_channel *channel = channel_file->private_data;
 412         struct lib_ring_buffer *buf;
 413         int stream_fd, ret;
 414         struct file *stream_file;
 415
 416         buf = channel->ops->buffer_read_open(channel->chan);
 417         if (!buf)
 418                 return -ENOENT;
 419
 420         stream_fd = get_unused_fd();
 421         if (stream_fd < 0) {
 422                 ret = stream_fd;
 423                 goto fd_error;
 424         }
 425         stream_file = anon_inode_getfile("[lttng_stream]",
 426                                          &lib_ring_buffer_file_operations,
 427                                          buf, O_RDWR);
 428         if (IS_ERR(stream_file)) {
 429                 ret = PTR_ERR(stream_file);
 430                 goto file_error;
 431         }
 432         /*
 433          * OPEN_FMODE, called within anon_inode_getfile/alloc_file, don't honor
 434          * FMODE_LSEEK, FMODE_PREAD nor FMODE_PWRITE. We need to read from this
 435          * file descriptor, so we set FMODE_PREAD here.
 436          */
 437         stream_file->f_mode |= FMODE_PREAD;
 438         fd_install(stream_fd, stream_file);
 439         /*
 440          * The stream holds a reference to the channel within the generic ring
 441          * buffer library, so no need to hold a refcount on the channel and
 442          * session files here.
 443          */
 444         return stream_fd;
 445
 446 file_error:
 447         put_unused_fd(stream_fd);
 448 fd_error:
 449         channel->ops->buffer_read_close(buf);
 450         return ret;
 451 }
 452
 453 static
 454 int lttng_abi_create_event(struct file *channel_file,
 455                            struct lttng_kernel_event __user *uevent_param)
 456 {
 457         struct ltt_channel *channel = channel_file->private_data;
 458         struct ltt_event *event;
 459         struct lttng_kernel_event event_param;
 460         int event_fd, ret;
 461         struct file *event_file;
 462
 463         if (copy_from_user(&event_param, uevent_param, sizeof(event_param)))
 464                 return -EFAULT;
 465         event_param.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 466         switch (event_param.instrumentation) {
 467         case LTTNG_KERNEL_KPROBE:
 468                 event_param.u.kprobe.symbol_name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 469                 break;
 470         case LTTNG_KERNEL_FUNCTION:
 471                 event_param.u.ftrace.symbol_name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 472                 break;
 473         default:
 474                 break;
 475         }
 476         event_fd = get_unused_fd();
 477         if (event_fd < 0) {
 478                 ret = event_fd;
 479                 goto fd_error;
 480         }
 481         event_file = anon_inode_getfile("[lttng_event]",
 482                                         &lttng_event_fops,
 483                                         NULL, O_RDWR);
 484         if (IS_ERR(event_file)) {
 485                 ret = PTR_ERR(event_file);
 486                 goto file_error;
 487         }
 488         /*
 489          * We tolerate no failure path after event creation. It will stay
 490          * invariant for the rest of the session.
 491          */
 492         event = ltt_event_create(channel, &event_param, NULL);
 493         if (!event) {
 494                 ret = -EINVAL;
 495                 goto event_error;
 496         }
 497         event_file->private_data = event;
 498         fd_install(event_fd, event_file);
 499         /* The event holds a reference on the channel */
 500         atomic_long_inc(&channel_file->f_count);
 501         return event_fd;
 502
 503 event_error:
 504         fput(event_file);
 505 file_error:
 506         put_unused_fd(event_fd);
 507 fd_error:
 508         return ret;
 509 }
 510
 511 /**
 512  *      lttng_channel_ioctl - lttng syscall through ioctl
 513  *
 514  *      @file: the file
 515  *      @cmd: the command
 516  *      @arg: command arg
 517  *
 518  *      This ioctl implements lttng commands:
 519  *      LTTNG_KERNEL_STREAM
 520  *              Returns an event stream file descriptor or failure.
 521  *              (typically, one event stream records events from one CPU)
 522  *      LTTNG_KERNEL_EVENT
 523  *              Returns an event file descriptor or failure.
 524  *      LTTNG_KERNEL_CONTEXT
 525  *              Prepend a context field to each event in the channel
 526  *      LTTNG_KERNEL_ENABLE
 527  *              Enable recording for events in this channel (weak enable)
 528  *      LTTNG_KERNEL_DISABLE
 529  *              Disable recording for events in this channel (strong disable)
 530  *
 531  * Channel and event file descriptors also hold a reference on the session.
 532  */
 533 static
 534 long lttng_channel_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 535 {
 536         struct ltt_channel *channel = file->private_data;
 537
 538         switch (cmd) {
 539         case LTTNG_KERNEL_STREAM:
 540                 return lttng_abi_open_stream(file);
 541         case LTTNG_KERNEL_EVENT:
 542                 return lttng_abi_create_event(file, (struct lttng_kernel_event __user *) arg);
 543         case LTTNG_KERNEL_CONTEXT:
 544                 return lttng_abi_add_context(file,
 545                                 (struct lttng_kernel_context __user *) arg,
 546                                 &channel->ctx, channel->session);
 547         case LTTNG_KERNEL_ENABLE:
 548                 return ltt_channel_enable(channel);
 549         case LTTNG_KERNEL_DISABLE:
 550                 return ltt_channel_disable(channel);
 551         default:
 552                 return -ENOIOCTLCMD;
 553         }
 554 }
 555
 556 /**
 557  *      lttng_metadata_ioctl - lttng syscall through ioctl
 558  *
 559  *      @file: the file
 560  *      @cmd: the command
 561  *      @arg: command arg
 562  *
 563  *      This ioctl implements lttng commands:
 564  *      LTTNG_KERNEL_STREAM
 565  *              Returns an event stream file descriptor or failure.
 566  *
 567  * Channel and event file descriptors also hold a reference on the session.
 568  */
 569 static
 570 long lttng_metadata_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 571 {
 572         switch (cmd) {
 573         case LTTNG_KERNEL_STREAM:
 574                 return lttng_abi_open_stream(file);
 575         default:
 576                 return -ENOIOCTLCMD;
 577         }
 578 }
 579
 580 /**
 581  *      lttng_channel_poll - lttng stream addition/removal monitoring
 582  *
 583  *      @file: the file
 584  *      @wait: poll table
 585  */
 586 unsigned int lttng_channel_poll(struct file *file, poll_table *wait)
 587 {
 588         struct ltt_channel *channel = file->private_data;
 589         unsigned int mask = 0;
 590
 591         if (file->f_mode & FMODE_READ) {
 592                 poll_wait_set_exclusive(wait);
 593                 poll_wait(file, channel->ops->get_hp_wait_queue(channel->chan),
 594                           wait);
 595
 596                 if (channel->ops->is_disabled(channel->chan))
 597                         return POLLERR;
 598                 if (channel->ops->is_finalized(channel->chan))
 599                         return POLLHUP;
 600                 else
 601                         return POLLIN | POLLRDNORM;
 602         }
 603         return mask;
 604
 605 }
 606
 607 static
 608 int lttng_channel_release(struct inode *inode, struct file *file)
 609 {
 610         struct ltt_channel *channel = file->private_data;
 611
 612         if (channel)
 613                 fput(channel->session->file);
 614         return 0;
 615 }
 616
 617 static const struct file_operations lttng_channel_fops = {
 618         .release = lttng_channel_release,
 619         .poll = lttng_channel_poll,
 620         .unlocked_ioctl = lttng_channel_ioctl,
 621 #ifdef CONFIG_COMPAT
 622         .compat_ioctl = lttng_channel_ioctl,
 623 #endif
 624 };
 625
 626 static const struct file_operations lttng_metadata_fops = {
 627         .release = lttng_channel_release,
 628         .unlocked_ioctl = lttng_metadata_ioctl,
 629 #ifdef CONFIG_COMPAT
 630         .compat_ioctl = lttng_metadata_ioctl,
 631 #endif
 632 };
 633
 634 /**
 635  *      lttng_event_ioctl - lttng syscall through ioctl
 636  *
 637  *      @file: the file
 638  *      @cmd: the command
 639  *      @arg: command arg
 640  *
 641  *      This ioctl implements lttng commands:
 642  *      LTTNG_KERNEL_CONTEXT
 643  *              Prepend a context field to each record of this event
 644  *      LTTNG_KERNEL_ENABLE
 645  *              Enable recording for this event (weak enable)
 646  *      LTTNG_KERNEL_DISABLE
 647  *              Disable recording for this event (strong disable)
 648  */
 649 static
 650 long lttng_event_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 651 {
 652         struct ltt_event *event = file->private_data;
 653
 654         switch (cmd) {
 655         case LTTNG_KERNEL_CONTEXT:
 656                 return lttng_abi_add_context(file,
 657                                 (struct lttng_kernel_context __user *) arg,
 658                                 &event->ctx, event->chan->session);
 659         case LTTNG_KERNEL_ENABLE:
 660                 return ltt_event_enable(event);
 661         case LTTNG_KERNEL_DISABLE:
 662                 return ltt_event_disable(event);
 663         default:
 664                 return -ENOIOCTLCMD;
 665         }
 666 }
 667
 668 static
 669 int lttng_event_release(struct inode *inode, struct file *file)
 670 {
 671         struct ltt_event *event = file->private_data;
 672
 673         if (event)
 674                 fput(event->chan->file);
 675         return 0;
 676 }
 677
 678 /* TODO: filter control ioctl */
 679 static const struct file_operations lttng_event_fops = {
 680         .release = lttng_event_release,
 681         .unlocked_ioctl = lttng_event_ioctl,
 682 #ifdef CONFIG_COMPAT
 683         .compat_ioctl = lttng_event_ioctl,
 684 #endif
 685 };
 686
 687 int __init ltt_debugfs_abi_init(void)
 688 {
 689         int ret = 0;
 690
 691         wrapper_vmalloc_sync_all();
 692         lttng_dentry = debugfs_create_file("lttng", S_IWUSR, NULL, NULL,
 693                                            &lttng_fops);
 694         if (IS_ERR(lttng_dentry) || !lttng_dentry) {
 695                 printk(KERN_ERR "Error creating LTTng control file\n");
 696                 ret = -ENOMEM;
 697                 goto error;
 698         }
 699 error:
 700         return ret;
 701 }
 702
 703 void __exit ltt_debugfs_abi_exit(void)
 704 {
 705         debugfs_remove(lttng_dentry);
 706 }