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 /*
  53  * Teardown management: opened file descriptors keep a refcount on the module,
  54  * so it can only exit when all file descriptors are closed.
  55  */
  56
  57 enum channel_type {
  58         PER_CPU_CHANNEL,
  59         METADATA_CHANNEL,
  60 };
  61
  62 static
  63 int lttng_abi_create_session(void)
  64 {
  65         struct ltt_session *session;
  66         struct file *session_file;
  67         int session_fd, ret;
  68
  69         session = ltt_session_create();
  70         if (!session)
  71                 return -ENOMEM;
  72         session_fd = get_unused_fd();
  73         if (session_fd < 0) {
  74                 ret = session_fd;
  75                 goto fd_error;
  76         }
  77         session_file = anon_inode_getfile("[lttng_session]",
  78                                           &lttng_session_fops,
  79                                           session, O_RDWR);
  80         if (IS_ERR(session_file)) {
  81                 ret = PTR_ERR(session_file);
  82                 goto file_error;
  83         }
  84         session->file = session_file;
  85         fd_install(session_fd, session_file);
  86         return session_fd;
  87
  88 file_error:
  89         put_unused_fd(session_fd);
  90 fd_error:
  91         ltt_session_destroy(session);
  92         return ret;
  93 }
  94
  95 static
  96 int lttng_abi_tracepoint_list(void)
  97 {
  98         struct file *tracepoint_list_file;
  99         int file_fd, ret;
 100
 101         file_fd = get_unused_fd();
 102         if (file_fd < 0) {
 103                 ret = file_fd;
 104                 goto fd_error;
 105         }
 106
 107         tracepoint_list_file = anon_inode_getfile("[lttng_session]",
 108                                           &lttng_tracepoint_list_fops,
 109                                           NULL, O_RDWR);
 110         if (IS_ERR(tracepoint_list_file)) {
 111                 ret = PTR_ERR(tracepoint_list_file);
 112                 goto file_error;
 113         }
 114         ret = lttng_tracepoint_list_fops.open(NULL, tracepoint_list_file);
 115         if (ret < 0)
 116                 goto open_error;
 117         fd_install(file_fd, tracepoint_list_file);
 118         if (file_fd < 0) {
 119                 ret = file_fd;
 120                 goto fd_error;
 121         }
 122         return file_fd;
 123
 124 open_error:
 125         fput(tracepoint_list_file);
 126 file_error:
 127         put_unused_fd(file_fd);
 128 fd_error:
 129         return ret;
 130 }
 131
 132 static
 133 long lttng_abi_tracer_version(struct file *file,
 134         struct lttng_kernel_tracer_version __user *uversion_param)
 135 {
 136         struct lttng_kernel_tracer_version v;
 137
 138         v.version = LTTNG_VERSION;
 139         v.patchlevel = LTTNG_PATCHLEVEL;
 140         v.sublevel = LTTNG_SUBLEVEL;
 141
 142         if (copy_to_user(uversion_param, &v, sizeof(v)))
 143                 return -EFAULT;
 144         return 0;
 145 }
 146
 147 static
 148 long lttng_abi_add_context(struct file *file,
 149         struct lttng_kernel_context __user *ucontext_param,
 150         struct lttng_ctx **ctx, struct ltt_session *session)
 151 {
 152         struct lttng_kernel_context context_param;
 153
 154         if (session->been_active)
 155                 return -EPERM;
 156
 157         if (copy_from_user(&context_param, ucontext_param, sizeof(context_param)))
 158                 return -EFAULT;
 159
 160         switch (context_param.ctx) {
 161         case LTTNG_KERNEL_CONTEXT_PID:
 162                 return lttng_add_pid_to_ctx(ctx);
 163         case LTTNG_KERNEL_CONTEXT_PRIO:
 164                 return lttng_add_prio_to_ctx(ctx);
 165         case LTTNG_KERNEL_CONTEXT_NICE:
 166                 return lttng_add_nice_to_ctx(ctx);
 167         case LTTNG_KERNEL_CONTEXT_VPID:
 168                 return lttng_add_vpid_to_ctx(ctx);
 169         case LTTNG_KERNEL_CONTEXT_TID:
 170                 return lttng_add_tid_to_ctx(ctx);
 171         case LTTNG_KERNEL_CONTEXT_VTID:
 172                 return lttng_add_vtid_to_ctx(ctx);
 173         case LTTNG_KERNEL_CONTEXT_PPID:
 174                 return lttng_add_ppid_to_ctx(ctx);
 175         case LTTNG_KERNEL_CONTEXT_VPPID:
 176                 return lttng_add_vppid_to_ctx(ctx);
 177         case LTTNG_KERNEL_CONTEXT_PERF_COUNTER:
 178                 context_param.u.perf_counter.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 179                 return lttng_add_perf_counter_to_ctx(context_param.u.perf_counter.type,
 180                                 context_param.u.perf_counter.config,
 181                                 context_param.u.perf_counter.name,
 182                                 ctx);
 183         case LTTNG_KERNEL_CONTEXT_COMM:
 184                 return lttng_add_comm_to_ctx(ctx);
 185         default:
 186                 return -EINVAL;
 187         }
 188 }
 189
 190 /**
 191  *      lttng_ioctl - lttng syscall through ioctl
 192  *
 193  *      @file: the file
 194  *      @cmd: the command
 195  *      @arg: command arg
 196  *
 197  *      This ioctl implements lttng commands:
 198  *      LTTNG_KERNEL_SESSION
 199  *              Returns a LTTng trace session file descriptor
 200  *      LTTNG_KERNEL_TRACER_VERSION
 201  *              Returns the LTTng kernel tracer version
 202  *      LTTNG_KERNEL_TRACEPOINT_LIST
 203  *              Returns a file descriptor listing available tracepoints
 204  *      LTTNG_KERNEL_WAIT_QUIESCENT
 205  *              Returns after all previously running probes have completed
 206  *
 207  * The returned session will be deleted when its file descriptor is closed.
 208  */
 209 static
 210 long lttng_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 211 {
 212         switch (cmd) {
 213         case LTTNG_KERNEL_SESSION:
 214                 return lttng_abi_create_session();
 215         case LTTNG_KERNEL_TRACER_VERSION:
 216                 return lttng_abi_tracer_version(file,
 217                                 (struct lttng_kernel_tracer_version __user *) arg);
 218         case LTTNG_KERNEL_TRACEPOINT_LIST:
 219                 return lttng_abi_tracepoint_list();
 220         case LTTNG_KERNEL_WAIT_QUIESCENT:
 221                 synchronize_trace();
 222                 return 0;
 223         default:
 224                 return -ENOIOCTLCMD;
 225         }
 226 }
 227
 228 static const struct file_operations lttng_fops = {
 229         .owner = THIS_MODULE,
 230         .unlocked_ioctl = lttng_ioctl,
 231 #ifdef CONFIG_COMPAT
 232         .compat_ioctl = lttng_ioctl,
 233 #endif
 234 };
 235
 236 /*
 237  * We tolerate no failure in this function (if one happens, we print a dmesg
 238  * error, but cannot return any error, because the channel information is
 239  * invariant.
 240  */
 241 static
 242 void lttng_metadata_create_events(struct file *channel_file)
 243 {
 244         struct ltt_channel *channel = channel_file->private_data;
 245         static struct lttng_kernel_event metadata_params = {
 246                 .instrumentation = LTTNG_KERNEL_TRACEPOINT,
 247                 .name = "lttng_metadata",
 248         };
 249         struct ltt_event *event;
 250         int ret;
 251
 252         /*
 253          * We tolerate no failure path after event creation. It will stay
 254          * invariant for the rest of the session.
 255          */
 256         event = ltt_event_create(channel, &metadata_params, NULL);
 257         if (!event) {
 258                 ret = -EINVAL;
 259                 goto create_error;
 260         }
 261         return;
 262
 263 create_error:
 264         WARN_ON(1);
 265         return;         /* not allowed to return error */
 266 }
 267
 268 static
 269 int lttng_abi_create_channel(struct file *session_file,
 270                              struct lttng_kernel_channel __user *uchan_param,
 271                              enum channel_type channel_type)
 272 {
 273         struct ltt_session *session = session_file->private_data;
 274         const struct file_operations *fops;
 275         const char *transport_name;
 276         struct ltt_channel *chan;
 277         struct file *chan_file;
 278         struct lttng_kernel_channel chan_param;
 279         int chan_fd;
 280         int ret = 0;
 281
 282         if (copy_from_user(&chan_param, uchan_param, sizeof(chan_param)))
 283                 return -EFAULT;
 284         chan_fd = get_unused_fd();
 285         if (chan_fd < 0) {
 286                 ret = chan_fd;
 287                 goto fd_error;
 288         }
 289         chan_file = anon_inode_getfile("[lttng_channel]",
 290                                        &lttng_channel_fops,
 291                                        NULL, O_RDWR);
 292         if (IS_ERR(chan_file)) {
 293                 ret = PTR_ERR(chan_file);
 294                 goto file_error;
 295         }
 296         switch (channel_type) {
 297         case PER_CPU_CHANNEL:
 298                 if (chan_param.output == LTTNG_KERNEL_SPLICE) {
 299                         transport_name = chan_param.overwrite ?
 300                                 "relay-overwrite" : "relay-discard";
 301                 } else if (chan_param.output == LTTNG_KERNEL_MMAP) {
 302                         transport_name = chan_param.overwrite ?
 303                                 "relay-overwrite-mmap" : "relay-discard-mmap";
 304                 } else {
 305                         return -EINVAL;
 306                 }
 307                 fops = &lttng_channel_fops;
 308                 break;
 309         case METADATA_CHANNEL:
 310                 if (chan_param.output == LTTNG_KERNEL_SPLICE)
 311                         transport_name = "relay-metadata";
 312                 else if (chan_param.output == LTTNG_KERNEL_MMAP)
 313                         transport_name = "relay-metadata-mmap";
 314                 else
 315                         return -EINVAL;
 316                 fops = &lttng_metadata_fops;
 317                 break;
 318         default:
 319                 transport_name = "<unknown>";
 320                 break;
 321         }
 322         /*
 323          * We tolerate no failure path after channel creation. It will stay
 324          * invariant for the rest of the session.
 325          */
 326         chan = ltt_channel_create(session, transport_name, NULL,
 327                                   chan_param.subbuf_size,
 328                                   chan_param.num_subbuf,
 329                                   chan_param.switch_timer_interval,
 330                                   chan_param.read_timer_interval);
 331         if (!chan) {
 332                 ret = -EINVAL;
 333                 goto chan_error;
 334         }
 335         chan->file = chan_file;
 336         chan_file->private_data = chan;
 337         fd_install(chan_fd, chan_file);
 338         if (channel_type == METADATA_CHANNEL) {
 339                 session->metadata = chan;
 340                 lttng_metadata_create_events(chan_file);
 341         }
 342
 343         /* The channel created holds a reference on the session */
 344         atomic_long_inc(&session_file->f_count);
 345
 346         return chan_fd;
 347
 348 chan_error:
 349         fput(chan_file);
 350 file_error:
 351         put_unused_fd(chan_fd);
 352 fd_error:
 353         return ret;
 354 }
 355
 356 /**
 357  *      lttng_session_ioctl - lttng session fd ioctl
 358  *
 359  *      @file: the file
 360  *      @cmd: the command
 361  *      @arg: command arg
 362  *
 363  *      This ioctl implements lttng commands:
 364  *      LTTNG_KERNEL_CHANNEL
 365  *              Returns a LTTng channel file descriptor
 366  *      LTTNG_KERNEL_ENABLE
 367  *              Enables tracing for a session (weak enable)
 368  *      LTTNG_KERNEL_DISABLE
 369  *              Disables tracing for a session (strong disable)
 370  *      LTTNG_KERNEL_METADATA
 371  *              Returns a LTTng metadata file descriptor
 372  *
 373  * The returned channel will be deleted when its file descriptor is closed.
 374  */
 375 static
 376 long lttng_session_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 377 {
 378         struct ltt_session *session = file->private_data;
 379
 380         switch (cmd) {
 381         case LTTNG_KERNEL_CHANNEL:
 382                 return lttng_abi_create_channel(file,
 383                                 (struct lttng_kernel_channel __user *) arg,
 384                                 PER_CPU_CHANNEL);
 385         case LTTNG_KERNEL_SESSION_START:
 386         case LTTNG_KERNEL_ENABLE:
 387                 return ltt_session_enable(session);
 388         case LTTNG_KERNEL_SESSION_STOP:
 389         case LTTNG_KERNEL_DISABLE:
 390                 return ltt_session_disable(session);
 391         case LTTNG_KERNEL_METADATA:
 392                 return lttng_abi_create_channel(file,
 393                                 (struct lttng_kernel_channel __user *) arg,
 394                                 METADATA_CHANNEL);
 395         default:
 396                 return -ENOIOCTLCMD;
 397         }
 398 }
 399
 400 /*
 401  * Called when the last file reference is dropped.
 402  *
 403  * Big fat note: channels and events are invariant for the whole session after
 404  * their creation. So this session destruction also destroys all channel and
 405  * event structures specific to this session (they are not destroyed when their
 406  * individual file is released).
 407  */
 408 static
 409 int lttng_session_release(struct inode *inode, struct file *file)
 410 {
 411         struct ltt_session *session = file->private_data;
 412
 413         if (session)
 414                 ltt_session_destroy(session);
 415         return 0;
 416 }
 417
 418 static const struct file_operations lttng_session_fops = {
 419         .owner = THIS_MODULE,
 420         .release = lttng_session_release,
 421         .unlocked_ioctl = lttng_session_ioctl,
 422 #ifdef CONFIG_COMPAT
 423         .compat_ioctl = lttng_session_ioctl,
 424 #endif
 425 };
 426
 427 static
 428 int lttng_abi_open_stream(struct file *channel_file)
 429 {
 430         struct ltt_channel *channel = channel_file->private_data;
 431         struct lib_ring_buffer *buf;
 432         int stream_fd, ret;
 433         struct file *stream_file;
 434
 435         buf = channel->ops->buffer_read_open(channel->chan);
 436         if (!buf)
 437                 return -ENOENT;
 438
 439         stream_fd = get_unused_fd();
 440         if (stream_fd < 0) {
 441                 ret = stream_fd;
 442                 goto fd_error;
 443         }
 444         stream_file = anon_inode_getfile("[lttng_stream]",
 445                                          &lib_ring_buffer_file_operations,
 446                                          buf, O_RDWR);
 447         if (IS_ERR(stream_file)) {
 448                 ret = PTR_ERR(stream_file);
 449                 goto file_error;
 450         }
 451         /*
 452          * OPEN_FMODE, called within anon_inode_getfile/alloc_file, don't honor
 453          * FMODE_LSEEK, FMODE_PREAD nor FMODE_PWRITE. We need to read from this
 454          * file descriptor, so we set FMODE_PREAD here.
 455          */
 456         stream_file->f_mode |= FMODE_PREAD;
 457         fd_install(stream_fd, stream_file);
 458         /*
 459          * The stream holds a reference to the channel within the generic ring
 460          * buffer library, so no need to hold a refcount on the channel and
 461          * session files here.
 462          */
 463         return stream_fd;
 464
 465 file_error:
 466         put_unused_fd(stream_fd);
 467 fd_error:
 468         channel->ops->buffer_read_close(buf);
 469         return ret;
 470 }
 471
 472 static
 473 int lttng_abi_create_event(struct file *channel_file,
 474                            struct lttng_kernel_event __user *uevent_param)
 475 {
 476         struct ltt_channel *channel = channel_file->private_data;
 477         struct ltt_event *event;
 478         struct lttng_kernel_event event_param;
 479         int event_fd, ret;
 480         struct file *event_file;
 481
 482         if (copy_from_user(&event_param, uevent_param, sizeof(event_param)))
 483                 return -EFAULT;
 484         event_param.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 485         switch (event_param.instrumentation) {
 486         case LTTNG_KERNEL_KPROBE:
 487                 event_param.u.kprobe.symbol_name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 488                 break;
 489         case LTTNG_KERNEL_FUNCTION:
 490                 event_param.u.ftrace.symbol_name[LTTNG_SYM_NAME_LEN - 1] = '\0';
 491                 break;
 492         default:
 493                 break;
 494         }
 495         event_fd = get_unused_fd();
 496         if (event_fd < 0) {
 497                 ret = event_fd;
 498                 goto fd_error;
 499         }
 500         event_file = anon_inode_getfile("[lttng_event]",
 501                                         &lttng_event_fops,
 502                                         NULL, O_RDWR);
 503         if (IS_ERR(event_file)) {
 504                 ret = PTR_ERR(event_file);
 505                 goto file_error;
 506         }
 507         /*
 508          * We tolerate no failure path after event creation. It will stay
 509          * invariant for the rest of the session.
 510          */
 511         event = ltt_event_create(channel, &event_param, NULL);
 512         if (!event) {
 513                 ret = -EINVAL;
 514                 goto event_error;
 515         }
 516         event_file->private_data = event;
 517         fd_install(event_fd, event_file);
 518         /* The event holds a reference on the channel */
 519         atomic_long_inc(&channel_file->f_count);
 520         return event_fd;
 521
 522 event_error:
 523         fput(event_file);
 524 file_error:
 525         put_unused_fd(event_fd);
 526 fd_error:
 527         return ret;
 528 }
 529
 530 /**
 531  *      lttng_channel_ioctl - lttng syscall through ioctl
 532  *
 533  *      @file: the file
 534  *      @cmd: the command
 535  *      @arg: command arg
 536  *
 537  *      This ioctl implements lttng commands:
 538  *      LTTNG_KERNEL_STREAM
 539  *              Returns an event stream file descriptor or failure.
 540  *              (typically, one event stream records events from one CPU)
 541  *      LTTNG_KERNEL_EVENT
 542  *              Returns an event file descriptor or failure.
 543  *      LTTNG_KERNEL_CONTEXT
 544  *              Prepend a context field to each event in the channel
 545  *      LTTNG_KERNEL_ENABLE
 546  *              Enable recording for events in this channel (weak enable)
 547  *      LTTNG_KERNEL_DISABLE
 548  *              Disable recording for events in this channel (strong disable)
 549  *
 550  * Channel and event file descriptors also hold a reference on the session.
 551  */
 552 static
 553 long lttng_channel_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 554 {
 555         struct ltt_channel *channel = file->private_data;
 556
 557         switch (cmd) {
 558         case LTTNG_KERNEL_STREAM:
 559                 return lttng_abi_open_stream(file);
 560         case LTTNG_KERNEL_EVENT:
 561                 return lttng_abi_create_event(file, (struct lttng_kernel_event __user *) arg);
 562         case LTTNG_KERNEL_CONTEXT:
 563                 return lttng_abi_add_context(file,
 564                                 (struct lttng_kernel_context __user *) arg,
 565                                 &channel->ctx, channel->session);
 566         case LTTNG_KERNEL_ENABLE:
 567                 return ltt_channel_enable(channel);
 568         case LTTNG_KERNEL_DISABLE:
 569                 return ltt_channel_disable(channel);
 570         default:
 571                 return -ENOIOCTLCMD;
 572         }
 573 }
 574
 575 /**
 576  *      lttng_metadata_ioctl - lttng syscall through ioctl
 577  *
 578  *      @file: the file
 579  *      @cmd: the command
 580  *      @arg: command arg
 581  *
 582  *      This ioctl implements lttng commands:
 583  *      LTTNG_KERNEL_STREAM
 584  *              Returns an event stream file descriptor or failure.
 585  *
 586  * Channel and event file descriptors also hold a reference on the session.
 587  */
 588 static
 589 long lttng_metadata_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 590 {
 591         switch (cmd) {
 592         case LTTNG_KERNEL_STREAM:
 593                 return lttng_abi_open_stream(file);
 594         default:
 595                 return -ENOIOCTLCMD;
 596         }
 597 }
 598
 599 /**
 600  *      lttng_channel_poll - lttng stream addition/removal monitoring
 601  *
 602  *      @file: the file
 603  *      @wait: poll table
 604  */
 605 unsigned int lttng_channel_poll(struct file *file, poll_table *wait)
 606 {
 607         struct ltt_channel *channel = file->private_data;
 608         unsigned int mask = 0;
 609
 610         if (file->f_mode & FMODE_READ) {
 611                 poll_wait_set_exclusive(wait);
 612                 poll_wait(file, channel->ops->get_hp_wait_queue(channel->chan),
 613                           wait);
 614
 615                 if (channel->ops->is_disabled(channel->chan))
 616                         return POLLERR;
 617                 if (channel->ops->is_finalized(channel->chan))
 618                         return POLLHUP;
 619                 if (channel->ops->buffer_has_read_closed_stream(channel->chan))
 620                         return POLLIN | POLLRDNORM;
 621                 return 0;
 622         }
 623         return mask;
 624
 625 }
 626
 627 static
 628 int lttng_channel_release(struct inode *inode, struct file *file)
 629 {
 630         struct ltt_channel *channel = file->private_data;
 631
 632         if (channel)
 633                 fput(channel->session->file);
 634         return 0;
 635 }
 636
 637 static const struct file_operations lttng_channel_fops = {
 638         .owner = THIS_MODULE,
 639         .release = lttng_channel_release,
 640         .poll = lttng_channel_poll,
 641         .unlocked_ioctl = lttng_channel_ioctl,
 642 #ifdef CONFIG_COMPAT
 643         .compat_ioctl = lttng_channel_ioctl,
 644 #endif
 645 };
 646
 647 static const struct file_operations lttng_metadata_fops = {
 648         .owner = THIS_MODULE,
 649         .release = lttng_channel_release,
 650         .unlocked_ioctl = lttng_metadata_ioctl,
 651 #ifdef CONFIG_COMPAT
 652         .compat_ioctl = lttng_metadata_ioctl,
 653 #endif
 654 };
 655
 656 /**
 657  *      lttng_event_ioctl - lttng syscall through ioctl
 658  *
 659  *      @file: the file
 660  *      @cmd: the command
 661  *      @arg: command arg
 662  *
 663  *      This ioctl implements lttng commands:
 664  *      LTTNG_KERNEL_CONTEXT
 665  *              Prepend a context field to each record of this event
 666  *      LTTNG_KERNEL_ENABLE
 667  *              Enable recording for this event (weak enable)
 668  *      LTTNG_KERNEL_DISABLE
 669  *              Disable recording for this event (strong disable)
 670  */
 671 static
 672 long lttng_event_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 673 {
 674         struct ltt_event *event = file->private_data;
 675
 676         switch (cmd) {
 677         case LTTNG_KERNEL_CONTEXT:
 678                 return lttng_abi_add_context(file,
 679                                 (struct lttng_kernel_context __user *) arg,
 680                                 &event->ctx, event->chan->session);
 681         case LTTNG_KERNEL_ENABLE:
 682                 return ltt_event_enable(event);
 683         case LTTNG_KERNEL_DISABLE:
 684                 return ltt_event_disable(event);
 685         default:
 686                 return -ENOIOCTLCMD;
 687         }
 688 }
 689
 690 static
 691 int lttng_event_release(struct inode *inode, struct file *file)
 692 {
 693         struct ltt_event *event = file->private_data;
 694
 695         if (event)
 696                 fput(event->chan->file);
 697         return 0;
 698 }
 699
 700 /* TODO: filter control ioctl */
 701 static const struct file_operations lttng_event_fops = {
 702         .owner = THIS_MODULE,
 703         .release = lttng_event_release,
 704         .unlocked_ioctl = lttng_event_ioctl,
 705 #ifdef CONFIG_COMPAT
 706         .compat_ioctl = lttng_event_ioctl,
 707 #endif
 708 };
 709
 710 int __init ltt_debugfs_abi_init(void)
 711 {
 712         int ret = 0;
 713
 714         wrapper_vmalloc_sync_all();
 715         lttng_dentry = debugfs_create_file("lttng", S_IWUSR, NULL, NULL,
 716                                            &lttng_fops);
 717         if (IS_ERR(lttng_dentry) || !lttng_dentry) {
 718                 printk(KERN_ERR "Error creating LTTng control file\n");
 719                 ret = -ENOMEM;
 720                 goto error;
 721         }
 722 error:
 723         return ret;
 724 }
 725
 726 void __exit ltt_debugfs_abi_exit(void)
 727 {
 728         debugfs_remove(lttng_dentry);
 729 }